publicationDate,title,abstract,id
2024-02-13,Forecasts for Constraining Lorentz-violating Damping of Gravitational Waves from Compact Binary Inspirals,"Violation of Lorentz symmetry can result in two distinct effects in the
propagation of the gravitational waves (GWs). One is a modified dispersion
relation and another is a frequency-dependent damping of GWs. While the former
has been extensively studied in the literature, in this paper we concentrate on
the frequency-dependent damping effect that arises from several specific
Lorentz-violating theories, such as spatial covariant gravities,
Ho\v{r}ava-Lifshitz gravities, etc. This Lorentz-violating damping effect
changes the damping rate of GWs at different frequencies and leads to an
amplitude correction to the GW waveform of compact binary inspiral systems.
With this modified waveform, we then use the Fisher information matrix to
investigate the prospects of constraining the Lorentz-violating damping effect
with GW observations. We consider both ground-based and space-based GW
detectors, including the advanced LIGO, Einstein Telescope, Cosmic Explorer
(CE), Taiji, TianQin, and LISA. Our results indicate that the ground-based
detectors in general give tighter constraints than those from the space-based
detectors. Among the considered three ground-based detectors, CE can give the
tightest constraints on the Lorentz-violating damping effect, which improves
the current constraint from LIGO-Virgo-KAGRA events by about 8 times.",2402.08240v1
2022-01-20,Derivation of the linear Boltzmann equation from the damped quantum Lorentz gas with a general scatterer configuration,"It is a fundamental problem in mathematical physics to derive macroscopic
transport equations from microscopic models. In this paper we derive the linear
Boltzmann equation in the low-density limit of a damped quantum Lorentz gas for
a large class of deterministic and random scatterer configurations. Previously
this result was known only for the single-scatterer problem on the flat torus,
and for uniformly random scatterer configurations where no damping is required.
The damping is critical in establishing convergence -- in the absence of
damping the limiting behaviour depends on the exact configuration under
consideration, and indeed, the linear Boltzmann equation is not expected to
appear for periodic and other highly ordered configurations.",2201.08229v2
2015-01-19,Relativistic Lagrangians for the Lorentz-Dirac equation,"We present two types of relativistic Lagrangians for the Lorentz-Dirac
equation written in terms of an arbitrary world-line parameter. One of the
Lagrangians contains an exponential damping function of the proper time and
explicitly depends on the world-line parameter. Another Lagrangian includes
additional cross-terms consisting of auxiliary dynamical variables and does not
depend explicitly on the world-line parameter. We demonstrate that both the
Lagrangians actually yield the Lorentz-Dirac equation with a source-like term.",1501.04551v2
2007-01-16,Influence of Lorentz violation on Dirac quasinormal modes in the Schwarzschild black hole spacetime,"Using the third-order WKB approximation and monodromy methods, we investigate
the influence of Lorentz violating coefficient $b$ (associated with a special
axial-vector $b_{\mu}$ field) on Dirac quasinormal modes in the Schwarzschild
black hole spacetime. At fundamental overtone, the real part decreases linearly
as the parameter $b$ increases. But the variation of the imaginary part with
$b$ becomes more complex. For the larger multiple moment $k$, the magnitude of
imaginary part increases with the increase of $b$, which means that presence of
Lorentz violation makes Dirac field damps more rapidly. At high overtones, it
is found that the real part of high-damped quasinormal frequency does not tend
to zero, which is quite a different from the symptotic Dirac quasinormal modes
without Lorentz violation.",0701089v1
2001-04-17,Scattering and radiation damping in gyroscopic Lorentz electrodynamic,"Relativistic massive Lorentz electrodynamics (LED) is studied in a
``gyroscopic setup'' where the electromagnetic fields and the particle spin are
the only dynamical degrees of freedom.
  A rigorous proof of the global existence and uniqueness of the dynamics is
given for essentially the whole range of field strengths reasonable for a
classical theory.
  For a class of rotation-reflection symmetric field data it is shown that the
dynamics also satisfies the world-line equations for a non-moving Lorentz
electron, thus furnishing rigorous solutions of the full system of nonlinear
equations of LED.
  The previously proven soliton dynamics of the Lorentz electron is further
illucidated by showing that rotation-reflection symmetric deviations from the
soliton state of the renormalized particle die out exponentially fast through
radiation damping if the electrostatic mass is smaller than the bare rest mass.",0104023v2
2019-07-10,Determination of the damping co-efficient of electrons in optically transparent glasses at the true resonance frequency in the ultraviolet from an analysis of the Lorentz-Maxwell model of dispersion,"The Lorentz-Maxwell model of dispersion of light has been analyzed in this
paper to determine the true resonance frequency in the ultraviolet for the
electrons in optically transparent glasses and the damping coefficient at this
frequency. For this we needed the refractive indices of glass in the optical
frequency range. We argue that the true resonance condition in the absorption
region prevails when the frequency at which the absorption coefficient is
maximum is the same as the frequency at which the average energy per cycle of
the electrons is also a maximum. We have simultaneously solved the two
equations obtained from the two maxima conditions numerically to arrive at a
unique solution for the true resonance frequency and the damping coefficient at
this frequency. Assuming the damping coefficient to be constant over a small
frequency range in the absorption region, we have determined the frequencies at
which the extinction coefficient and the reflectance are maxima. These
frequencies match very well with the published data for silica glasses
available from the literature.",1907.04499v1
2005-04-25,Radiative Effect on Particle Acceleration via Relativistic Electromagnetic Expansion,"The radiation damping effect on the diamagnetic relativistic pulse
accelerator (DRPA) is studied in two-and-half dimensional Particle-in-Cell
(PIC) simulation with magnetized electron-positron plasmas. Self-consistently
solved radiation damping force converts particle energy to radiation energy.
The DRPA is still robust with radiation, and the Lorentz factor of the most
high energy particles reach more than two thousand before they decouple from
the electromagnetic pulse. Resulted emitted power from the pulse front is lower
in the radiative case than the estimation from the non-radiative case due to
the radiation damping. The emitted radiation is strongly linearly polarized and
peaked within few degrees from the direction of Poynting flux.",0504561v1
2023-06-21,The effect of singularities and damping on the spectra of photonic crystals,"Understanding the dispersive properties of photonic crystals is a fundamental
and well-studied problem. However, the introduction of singular permittivities
and damping complicates the otherwise straightforward theory. In this paper, we
study photonic crystals with a Drude-Lorentz model for the permittivity,
motivated by halide perovskites. We demonstrate how the introduction of
singularities and damping affects the spectral band structure and show how to
interpret the notion of a ""band gap"" in this setting. We present explicit
solutions for a one-dimensional model and show how integral operators can be
used to handle multi-dimensional systems.",2306.12254v1
2014-06-10,Wigner's Space-time Symmetries based on the Two-by-two Matrices of the Damped Harmonic Oscillators and the Poincaré Sphere,"The second-order differential equation for a damped harmonic oscillator can
be converted to two coupled first-order equations, with two two-by-two matrices
leading to the group $Sp(2)$. It is shown that this oscillator system contains
the essential features of Wigner's little groups dictating the internal
space-time symmetries of particles in the Lorentz-covariant world. The little
groups are the subgroups of the Lorentz group whose transformations leave the
four-momentum of a given particle invariant. It is shown that the damping modes
of the oscillator correspond to the little groups for massive and
imaginary-mass particles respectively. When the system makes the transition
from the oscillation to damping mode, it corresponds to the little group for
massless particles. Rotations around the momentum leave the four-momentum
invariant. This degree of freedom extends the $Sp(2)$ symmetry to that of
$SL(2,c)$ corresponding to the Lorentz group applicable to the four-dimensional
Minkowski space. The Poincar\'e sphere contains the $SL(2,c)$ symmetry. In
addition, it has a non-Lorentzian parameter allowing us to reduce the mass
continuously to zero. It is thus possible to construct the little group for
massless particles from that of the massive particle by reducing its mass to
zero. Spin-1/2 particles and spin-1 particles are discussed in detail.",1406.2403v1
2023-04-18,Tests of modified gravitational wave propagations with gravitational waves,"Any violation of the fundamental principles of general relativity (GR),
including the violations of the equivalence principle and parity/Lorentz
symmetries, could induce possible derivations in the gravitational wave (GW)
propagations so they can be tested/constrained directly by the GW data. In this
letter, we present a universal parametrization for characterizing possible
derivations from GW propagations in GR. This parametrization provides a general
framework for exploring possible modified GW propagations arising from a large
number of modified theories of gravity. With this parameterization, we
construct the modified GW waveforms generated by the coalescence of compact
binaries with the effects of the gravitational parity/Lorentz violations, then
analyze the open data of compact binary merging events detected by
LIGO/Virgo/KAGRA collaboration. We do not find any signatures of gravitational
parity/Lorentz violations, thereby allowing us to place several of the most
stringent constraints on parity/Lorentz violations in gravity and a first
constraint on the Lorentz-violating damping effect in GW. This also represents
the most comprehensive tests on the modified GW propagations.",2304.09025v1
2010-04-27,Radiation Damping in a Non-Abelian Strongly-Coupled Gauge Theory,"We study a `dressed' or `composite' quark in strongly-coupled N=4
super-Yang-Mills (SYM), making use of the AdS/CFT correspondence. We show that
the standard string dynamics nicely captures the physics of the quark and its
surrounding quantum non-Abelian field configuration, making it possible to
derive a relativistic equation of motion that incorporates the effects of
radiation damping. From this equation one can deduce a non-standard dispersion
relation for the composite quark, as well as a Lorentz covariant formula for
its rate of radiation.",1004.4912v1
2011-07-15,"Aspects of General Relativity: Pseudo-Finsler extensions, Quasi-normal frequencies and Multiplication of tensorial distributions","This thesis is based on three different projects, all of them are directly
linked to the classical general theory of relativity, but they might have
consequences for quantum gravity as well. The first chapter deals with
pseudo-Finsler geometric extensions of the classical theory, these being ways
of naturally representing high-energy Lorentz symmetry violations. The second
chapter deals with the problem of highly damped quasi-normal modes related to
different types of black hole spacetimes. Besides the astrophysical meaning of
the quasi-normal modes, there are conjectures about the link between the highly
damped modes and black hole thermodynamics. The third chapter is related to the
topic of multiplication of tensorial distributions.",1107.2978v1
2013-10-21,A Critical History of Renormalization,"The history of renormalization is reviewed with a critical eye, starting with
Lorentz's theory of radiation damping, through perturbative QED with Dyson,
Gell-Mann & Low, and others, to Wilson's formulation and Polchinski's
functional equation, and applications to ""triviality"", and dark energy in
cosmology.",1310.5533v1
2001-07-25,Causal Classical Theory of Radiation Damping,"It is shown how initial conditions can be appropriately defined for the
integration of Lorentz-Dirac equations of motion. The integration is performed
\QTR{it}{forward} in time. The theory is applied to the case of the motion of
an electron in an intense laser pulse, relevant to nonlinear Compton
scattering.",0107062v1
2022-01-19,Active tuning of plasmon damping via light induced magnetism,"Circularly polarized optical excitation of plasmonic nanostructures causes
coherent circulating motion of their electrons, which in turn, gives rise to
strong optically induced magnetization - a phenomenon known as the inverse
Faraday effect (IFE). In this study we report how the IFE also significantly
decreases plasmon damping. By modulating the optical polarization state
incident on achiral plasmonic nanostructures from linear to circular, we
observe reversible increases of reflectance by 78% as well as simultaneous
increases of optical field concentration by 35.7% under 10^9 W/m^2 continuous
wave (CW) optical excitation. These signatures of decreased plasmon damping
were also monitored in the presence of an externally applied magnetic field
(0.2 T). The combined interactions allow an estimate of the light-induced
magnetization, which corresponds to an effective magnetic field of ~1.3 T
during circularly polarized CW excitation (10^9 W/m^2). We rationalize the
observed decreases in plasmon damping in terms of the Lorentz forces acting on
the circulating electron trajectories. Our results outline strategies for
actively modulating intrinsic losses in the metal, and thereby, the optical
mode quality and field concentration via opto-magnetic effects encoded in the
polarization state of incident light.",2201.07842v1
2017-07-21,Quasinormal ringing of black holes in Einstein aether theory,"The gravitational consequence of local Lorentz violation (LV) should show
itself in derivation of the characteristic quasinormal ringing of black hole
mergers from their general relativity case. In this paper, we study quasinormal
modes (QNMs) of the scalar and electromagnetic field perturbations to Einstein
aether black holes. We find that quasinormal ringing of the first kind aether
black hole is similar to that of another Lorentz violation model---the
QED-extension limit of standard model extension. These similarities between
completely different backgrounds may imply that LV in gravity sector and LV in
matter sector have some connections between themself: damping quasinormal
ringing of black holes more rapidly and prolonging its oscillation period. By
compared to Schwarzschild black hole, both the first and the second kind aether
black holes have larger damping rate and smaller real oscillation frequency of
QNMs. And the differences are from 0.7 percent to 35 percents, those could be
detected by new generation of gravitational antennas.",1707.06747v2
2023-09-27,Exploring antisymmetric tensor effects on black hole shadows and quasinormal frequencies,"This study explores the impact of antisymmetric tensor effects on spherically
symmetric black holes, investigating photon spheres, shadows, emission rate and
quasinormal frequencies in relation to a parameter which triggers the Lorentz
symmetry breaking. We examine these configurations without and with the
presence of a cosmological constant. In the first scenario, the Lorentz
violation parameter, denoted as $\lambda$, plays a pivotal role in reducing
both the photon sphere and the shadow radius, while also leading to a damping
effect on quasinormal frequencies. Conversely, in the second scenario, as the
values of the cosmological constant ($\Lambda$) increase, we observe an
expansion in the shadow radius. Also, we provide the constraints of the shadows
based on the analysis observational data obtained from the Event Horizon
Telescope (EHT) focusing on Sagittarius $A^{*}$ shadow images. Additionally,
with the increasing $\Lambda$, the associated gravitational wave frequencies
exhibit reduced damping modes.",2309.15778v3
2006-11-09,"Near field in quantum electrodynamics: Green functions, Lorentz condition, ""nonlocality in the small"", frustrated total reflection","Investigation of near field of QED requires the refuse from an averaging of
the Lorentz condition that smooths out some field peculiarities. Instead of it
Schwinger decomposition of the 4-potential with the Bogoliubov method of
interaction switching in time and in space regions is considered. At such
approach near field is describable by the part of covariant Green function of
QED, the fast-damping Schwinger function formed by longitudinal and scalar
components of Aμ none restricted by light cone. This description reveals
possibility of superluminal phenomena within the near field zone as a
""nonlocality in the small"". Some specification of Bogoliubov method allows, as
examples, descriptions of near fields of point-like charge and at FTIR
phenomena. Precisely such possibilities of nonlocal interactions are revealed
in the common QED expressions for the Van-der-Waals and Casimir interactions
and in the F\""{o}rster law.
  Key words: Lorentz condition, near field, propagators, superluminal, FTIR.
  PACS: 03.30.+p, 12.20.-m, 13.40.-f, 68.37.Uv.",0611098v1
2009-03-12,Generalized Lorentz-Dirac Equation for a Strongly-Coupled Gauge Theory,"We derive a semiclassical equation of motion for a `composite' quark in
strongly-coupled large-N_c N=4 super-Yang-Mills, making use of the AdS/CFT
correspondence. The resulting non-linear equation incorporates radiation
damping, and reduces to the standard Lorentz-Dirac equation for external forces
that are small on the scale of the quark Compton wavelength, but has no
self-accelerating or pre-accelerating solutions. From this equation one can
read off a non-standard dispersion relation for the quark, as well as a Lorentz
covariant formula for its radiation rate.",0903.2047v2
2012-02-14,Lorentz-violating vs ghost gravitons: the example of Weyl gravity,"We show that the ghost degrees of freedom of Einstein gravity with a Weyl
term can be eliminated by a simple mechanism that invokes local Lorentz
symmetry breaking. We demonstrate how the mechanism works in a cosmological
setting. The presence of the Weyl term forces a redefinition of the quantum
vacuum state of the tensor perturbations. As a consequence the amplitude of
their spectrum blows up when the Lorentz-violating scale becomes comparable to
the Hubble radius. Such a behaviour is in sharp contrast to what happens in
standard Weyl gravity where the gravitational ghosts smoothly damp out the
spectrum of primordial gravitational waves.",1202.3131v1
2014-12-29,The classical Maxwell-Lorentz electrodynamics aspects of the electron inertia problem within the Feynman proper time paradigm,"The Maxwell electromagnetic and the Lorentz type force equations are derived
in the framework of the R. Feynman proper time paradigm and the related vacuum
field theory approach. The electron inertia problem is analyzed within the
Lagrangian and Hamiltonian formalisms and the related pressure-energy
compensation principle. The modified Abraham- Lorentz damping radiation force
is derived, the electromagnetic electron mass origin is argued.",1412.8646v6
2023-08-03,Quasinormal modes of the spherical bumblebee black holes with a global monopole,"The bumblebee model is an extension of the Einstein-Maxwell theory that
allows for the spontaneous breaking of the Lorentz symmetry of the spacetime.
In this paper, we study the quasinormal modes of the spherical black holes in
this model that are characterized by a global monopole. We analyze the two
cases with a vanishing cosmological constant or a negative one (the anti-de
Sitter case). We find that the black holes are stable under the perturbation of
a massless scalar field. However, both the Lorentz symmetry breaking and the
global monopole have notable impacts on the evolution of the perturbation. The
Lorentz symmetry breaking may prolong or shorten the decay of the perturbation
according to the sign of the breaking parameter. The global monopole, on the
other hand, has different effects depending on whether a nonzero cosmological
constant presences: it reduces the damping of the perturbations for the case
with a vanishing cosmological constant, but has little influence for the
anti-de Sitter case.",2308.01575v1
1996-03-14,Dissipation and Topologically Massive Gauge Theories in Pseudoeuclidean Plane,"In the pseudo-euclidean metrics Chern-Simons gauge theory in the infrared
region is found to be associated with dissipative dynamics. In the infrared
limit the Lagrangian of 2+1 dimensional pseudo-euclidean topologically massive
electrodynamics has indeed the same form of the Lagrangian of the damped
harmonic oscillator. On the hyperbolic plane a set of two damped harmonic
oscillators, each other time-reversed, is shown to be equivalent to a single
undamped harmonic oscillator. The equations for the damped oscillators are
proven to be the same as the ones for the Lorentz force acting on two particles
carrying opposite charge in a constant magnetic field and in the electric
harmonic potential. This provides an immediate link with Chern-Simons-like
dynamics of Bloch electrons in solids propagating along the lattice plane with
hyperbolic energy surface. The symplectic structure of the reduced theory is
finally discussed in the Dirac constrained canonical formalism.",9603092v1
2009-08-26,Influence of an external magnetic field on forced turbulence in a swirling flow of liquid metal,"We report an experimental investigation on the influence of an external
magnetic field on forced 3D turbulence of liquid gallium in a closed vessel. We
observe an exponential damping of the turbulent velocity fluctuations as a
function of the interaction parameter N (ratio of Lorentz force over inertial
terms of the Navier-Stokes equation). The flow structures develop some
anisotropy but do not become bidimensional. From a dynamical viewpoint, the
damping first occurs homogeneously over the whole spectrum of frequencies. For
larger values of N, a very strong additional damping occurs at the highest
frequencies. However, the injected mechanical power remains independent of the
applied magnetic field. The simultaneous measurement of induced magnetic field
and electrical potential differences shows a very weak correlation between
magnetic field and velocity fluctuations. The observed reduction of the
fluctuations is in agreement with a previously proposed mechanism for the
saturation of turbulent dynamos and with the order of magnitude of the Von
Karman Sodium dynamo magnetic field.",0908.3821v1
2023-05-04,Vibrational resonance in a damped and two-frequency driven system of particle on a rotating parabola,"In the present work, we examine the role of nonlinearity in vibrational
resonance (VR) of a forced and damped form of a velocity-dependent potential
system. Many studies have focused on studying the vibrational resonance in
different potentials, like bistable potential, asymmetrically deformed
potential, and rough potential. In this connection, velocity-dependent
potential systems are very important from a physical point of view (Ex:
pion-pion interaction, cyclotrons and other electromagnetic devices influenced
by the Lorentz force, magnetrons, mass spectrometers). They also appear in
several mechanical contexts. In this paper, we consider a nonlinear dynamical
system with velocity-dependent potential along with additional damping and
driven forces, namely a particle moving on a rotating-parabola system, and
study the effect of two-frequency forcing with a wide difference in the
frequencies. We report that the system exhibits vibrational resonance in a
certain range of nonlinear strength. Using the method of separation of motions
(MSM), an analytical equation for the slow oscillations of the system is
obtained in terms of the parameters of the fast signal. The analytical
computations and the numerical studies concur well.",2305.02674v1
2023-11-14,Enhanced classical radiation damping of electronic cyclotron motion in the vicinity of the Van Hove singularity in a waveguide,"We study the damping process of electron cyclotron motion and the resulting
emission in a waveguide using the classical Friedrichs model without relying on
perturbation analysis such as Fermi's golden rule. A classical Van Hove
singularity appears at the lower bound (or cut-off frequency) of the dispersion
associated with each of the electromagnetic field modes in the waveguide. In
the vicinity of the Van Hove singularity, we found that not only is the decay
process associated with the resonance pole enhanced (amplification factor ~
$10^4$) but the branch-point effect is also comparably enhanced. As a result,
the timescale on which most of the decay occurs is dramatically shortened.
Further, this suggests that the non-Markovian branch point effect should be
experimentally observable in the vicinity of the Van Hove singularity. Our
treatment yields a physically-acceptable solution without the problematic
runaway solution that is well known to appear in the traditional treatment of
classical radiation damping based on the Abraham-Lorentz equation.",2311.08121v3
2002-09-27,Lorentz-Invariant Non-Commutative QED,"Lorentz-invariant non-commutative QED (NCQED) is constructed such that it
should be a part of Lorentz-invariant non-commutative standard model (NCSM), a
subject to be treated in later publications. Our NCSM is based on Connes'
observation that the total fermion field in the standard model may be regarded
as a bi-module over a flavor-color algebra. In this paper, it is shown that
there exist two massless gauge fields in NCQED which are interchanged by $C'$
transformation. Since $C'$ is reduced to the conventional charge conjugation
$C$ in the commutative limit, the two gauge fields become identical to the
photon field in the same limit, which couples to only four spinors with charges
$\pm 2,\pm 1.$ Following Carlson-Carone-Zobin, our NCQED respects Lorentz
invariance employing Doplicher-Fredenhagen-Roberts' algebra instead of the
usual algebra with constant $\theta^{\mu\nu}$. In the new version
$\theta^{\mu\nu}$ becomes an integration variable. We show using a simple NC
scalar model that the $\theta$ integration gives an {\it invariant} damping
factor instead of the oscillating one to the nonplanar self-energy diagram in
the one-loop approximation. Seiberg-Witten map shows that the $\theta$
expansion of NCQED generates exotic but well-motivated derivative interactions
beyond QED with allowed charges being only $0, \pm 1, \pm 2$.",0209234v2
2021-08-24,Jet Parameters in the Black-Hole X-Ray Binary MAXI J1820+070,"We study the jet in the hard state of the accreting black-hole binary MAXI
J1820+070. From the available radio-to-optical spectral and variability data,
we put strong constraints on the jet parameters. We find while it is not
possible to uniquely determine the jet Lorentz factor from the spectral and
variability properties alone, we can estimate the jet opening angle ($\approx
1.5\pm1^\circ$), the distance at which the jet starts emitting synchrotron
radiation ($\sim 3 \times10^{10}$cm), and the magnetic field strength there
($\sim$10$^4$G), with relatively low uncertainty, as they depend weakly on the
bulk Lorentz factor. We find the breaks in the variability power spectra from
radio to sub-mm are consistent with variability damping over the time scale
equal to the travel time along the jet at any Lorentz factor. This factor can
still be constrained by the electron-positron pair production rate within the
jet base, which we calculate based on the observed X-ray/soft gamma-ray
spectrum, and the jet power, required to be less than the accretion power. The
minimum ($\sim$1.5) and maximum ($\sim$4.5) Lorentz factors correspond to the
dominance of pairs and ions, and the minimum and maximum jet power,
respectively. We estimate the magnetic flux threading the black hole and find
the jet can be powered by the Blandford-Znajek mechanism in a
magnetically-arrested flow accretion flow. We point out the similarity of our
derived formalism to that of core shifts, observed in extragalactic radio
sources.",2108.10929v2
2017-10-20,Tidal dissipation in rotating fluid bodies: the presence of a magnetic field,"We investigate effects of the presence of a magnetic field on tidal
dissipation in rotating fluid bodies. We consider a simplified model consisting
of a rigid core and a fluid envelope, permeated by a background magnetic field
(either a dipolar field or a uniform axial field). The wavelike tidal responses
in the fluid layer are in the form of magnetic-Coriolis waves, which are
restored by both the Coriolis force and the Lorentz force. Energy dissipation
occurs through viscous damping and Ohmic damping of these waves. Our numerical
results show that the tidal dissipation can be dominated by Ohmic damping even
with a weak magnetic field. The presence of a magnetic field smooths out the
complicated frequency-dependence of the dissipation rate, and broadens the
frequency spectrum of the dissipation rate, depending on the strength of the
background magnetic field. However, the frequency-averaged dissipation is
independent of the strength and structure of the magnetic field, and of the
dissipative parameters, in the approximation that the wave-like response is
driven only by the Coriolis force acting on the non-wavelike tidal flow.
Indeed, the frequency-averaged dissipation quantity is in good agreement with
previous analytical results in the absence of magnetic fields. Our results
suggest that the frequency-averaged tidal dissipation of the wavelike
perturbations is insensitive to detailed damping mechanisms and dissipative
properties.",1710.07690v2
1998-10-09,A Technique of Direct Tension Measurement of a Strung Fine Wire,"We present a new technique of direct measurement of wire tensions in wire
chambers. A specially designed circuit plucks the wire using the Lorentz force
and measures the frequency of damped transverse oscillations of the wire. The
technique avoids the usual time-consuming necessity of tuning circuit parameter
to a resonance. It allows a fast and convenient determination of tensions and
is straightforward to implement.",9810023v1
2003-08-01,The pushing force of a propagating electromagnetic wave,"The effect of the electrodynamic forces on a charged particle in a
propagating plane electromagnetic wave is investigated. First it is pointed out
that for constant fields fulfilling the radiation condition there will be an
acceleration in the direction of the Poynting vector. When oscillating fields
are considered the Lorentz force on the particle only causes a drift, with
constant average velocity, in the direction of propagation of the wave, i.e.\
the direction of the Poynting vector. Finally, when the radiative reaction
(radiation damping) force is added the result is again an acceleration in the
direction of wave propagation. PACS classification numbers: 03.50.De, 41.60.-m,
41.75.Jv",0308007v1
2008-03-08,The Impact of Stochastic Primordial Magnetic Fields on the Scalar Contribution to Cosmic Microwave Background Anisotropies,"We study the impact of a stochastic background of primordial magnetic fields
on the scalar contribution of CMB anisotropies and on the matter power
spectrum. We give the correct initial conditions for cosmological perturbations
and the exact expressions for the energy density and Lorentz force associated
to the stochastic background of primordial magnetic fields, given a power-law
for their spectra cut at a damping scale. The dependence of the CMB temperature
and polarization spectra on the relevant parameters of the primordial magnetic
fields is illustrated.",0803.1246v1
2012-10-19,A kinetic model of radiating electrons,"A kinetic theory is developed to describe radiating electrons whose motion is
governed by the Lorentz-Dirac equation. This gives rise to a generalized Vlasov
equation coupled to an equation for the evolution of the physical submanifold
of phase space. The pathological solutions of the 1-particle theory may be
removed by expanding the latter equation in powers of $\tau := q^2/ 6\pi m$.
The radiation-induced change in entropy is explored, and its physical origin is
discussed. As a simple demonstration of the theory, the radiative damping rate
of longitudinal plasma waves is calculated.",1210.5467v1
2013-02-26,Modelling Fast-Alfvén Mode Conversion Using SPARC,"We successfully utilise the SPARC code to model fast-Alfv\'en mode conversion
in the region $c_A \gg c_S$ via 3-D MHD numerical simulations of helioseismic
waves within constant inclined magnetic field configurations. This was achieved
only after empirically modifying the background density and gravitational
stratifications in the upper layers of our computational box, as opposed to
imposing a traditional Lorentz Force limiter, to ensure a manageable timestep.
We found that the latter approach inhibits the fast-Alfv\'en mode conversion
process by severely damping the magnetic flux above the surface.",1302.6301v1
2014-02-11,Radiation reaction at the level of the action,"The aim of this paper is to highlight a recently proposed method for the
treatment of classical radiative effects, in particular radiation reaction, via
effective field theory methods. We emphasize important features of the method,
and in particular the doubling of fields. We apply the method to two simple
systems: for the mass-rope system in 1+1 dimensions we derive an effective
action for the mass which describes a damped harmonic oscillator, while for the
electromagnetic charge-field system, i.e. the system of an accelerating
electric charge in 3+1 d, we derive the leading Abraham-Lorentz-Dirac force.",1402.2610v2
2023-08-14,High-frequency homogenization for periodic dispersive media,"High-frequency homogenization is used to study dispersive media, containing
inclusions placed periodically, for which the properties of the material depend
on the frequency (Lorentz or Drude model with damping, for example). Effective
properties are obtained near a given point of the dispersion diagram in
frequency-wavenumber space. The asymptotic approximations of the dispersion
diagrams, and the wavefields, so obtained are then cross-validated via detailed
comparison with finite element method simulations in both one and two
dimensions.",2308.08559v1
2023-08-21,Quasinormal modes of the bumblebee black holes with a global monopole,"We engage in the computation of quasinormal modes associated with scalar and
Dirac fields around spherically symmetric black holes with a global monopole in
bumblebee gravity. The frequency of oscillation and the damping rate exhibit
significant decreasing as the global monopole parameter is increased. An
intriguing observation arises in the extreme limit, where the quasinormal modes
manifest a form of universal behavior: the actual oscillation frequency remains
unaltered despite variations in the Lorentz symmetry breaking (LSB) parameter.
Our calculations are conducted through two distinct methods, both of which
yield results that align remarkably well. Furthermore, we derive an analytical
formula for quasinormal modes within the eikonal approximation.",2308.10412v1
2003-10-21,Photon mass and cosmological constant bounds from spacetime torsion,"Photon mass and Cartan contortion bounds recently obtained from tiny Lorentz
violation observations in cosmology are used to find a limit of ${\lambda}\le
10^{-4}{\alpha}$ for the massive photon-torsion dimensionless coupling. Here
${\alpha}$ represents the fine-structure constant. A gauge invariant Proca
electrodynamics in spacetime endowed with torsion in de Sitter spacetime is
used to obtain an upper bound for the present value of the cosmological
constant given by ${\Lambda}\le 10^{-56} cm^{-2}$. This result is obtained in
regions of the universe where the photons are massless. A relation between the
contortion, photon mass and the radius of the universe is obtained. The Proca
electrodynamics with torsion and the radius of the universe allow us to place
more stringent bounds for the photon mass of $m_{\gamma}{\le} 10^{-44} GeV$
which is only two orders of magnitude lower than the astronomical bounds given
by the PARTICLE DATA GROUP (PDG). We also show that charge is locally conserved
in de Sitter spacetime with torsion and that plane waves are shown to be
damping by contortion inhomogeneities while dispersion is isotropic and
therefore Proca-Cartan photons do not violate Lorentz invariance.",0310595v1
2010-08-07,Fermi acceleration and suppression of Fermi acceleration in a time-dependent Lorentz Gas,"We study some dynamical properties of a Lorentz gas. We have considered both
the static and time dependent boundary. For the static case we have shown that
the system has a chaotic component characterized with a positive Lyapunov
Exponent. For the time-dependent perturbation we describe the model using a
four-dimensional nonlinear map. The behaviour of the average velocity is
considered in two situations (i) non-dissipative and (ii) dissipative. Our
results show that the unlimited energy growth is observed for the
non-dissipative case. However, when dissipation, via damping coefficients, is
introduced the senary changes and the unlimited engergy growth is suppressed.
The behaviour of the average velocity is described using scaling approach.",1008.1344v2
2010-11-05,Alfven seismic vibrations of crustal solid-state plasma in quaking paramagnetic neutron star,"Magneto-solid-mechanical model of two-component, core-crust, paramagnetic
neutron star responding to quake-induced perturbation by differentially
rotational, torsional, oscillations of crustal electron-nuclear solid-state
plasma about axis of magnetic field frozen in the immobile paramagnetic core is
developed. Particular attention is given to the node-free torsional
crust-against-core vibrations under combined action of Lorentz magnetic and
Hooke's elastic forces; the damping is attributed to Newtonian force of shear
viscose stresses in crustal solid-state plasma. The spectral formulae for the
frequency and lifetime of this toroidal mode are derived in analytic form and
discussed in the context of quasi-periodic oscillations of the X-ray outburst
flux from quaking magnetars. The application of obtained theoretical spectra to
modal analysis of available data on frequencies of oscillating outburst
emission suggests that detected variability is the manifestation of crustal
Alfven's seismic vibrations restored by Lorentz force of magnetic field
stresses.",1011.1346v2
2011-06-06,Frictional damping in radiative electrodynamics and its scaling to macroscopic systems,"Radiation force in Abraham-Lorentz-Dirac equation is revisited for possible
signature of irreversible action in the dynamics. The analysis shows that the
classical electron can dissipate out a certain fraction of field energy that
distinguishes itself from the well known Larmor radiation loss. The thermal
power loss is shown to follow bi-quadratic acceleration functionality, which is
akin to the characteristics of Hawking-Unruh radiation emission from warm
surrounding field of a non-inertial observer. Reversibility in nonstationary
evolution is possible at the expense of power from concerned external field. By
revealing nonlocal mitigation characteristics in nonstationary evolutions, a
measure of dissipative relaxation in the radiative electrodynamics is worked
out to compare the two distinctly different modes of energy losses. The measure
is shown to be applicable uniquely in all scales of externally perturbed
systems undergoing nonstationary dynamics, and is used as a common thread to
explain frictional contributions of phonons and electrons reported for metals
in superconductive phase transitions.
  Key words: Abraham-Lorentz-Dirac equation, radiation force, Hawking-Unruh
radiation, frictional dissipation.",1106.1135v2
2013-03-23,Stringent constraint on neutrino Lorentz-invariance violation from the two IceCube PeV neutrinos,"It has been speculated that Lorentz-invariance violation (LIV) might be
generated by quantum-gravity (QG) effects. As a consequence, particles may not
travel at the universal speed of light. In particular, superluminal
extragalactic neutrinos would rapidly lose energy via the bremssthralung of
electron-positron pairs (nu -> nu e+ e-), damping their initial energy into
electromagnetic cascades, a figure constrained by Fermi-LAT data. We show that
the two cascade neutrino events with energies around 1 PeV recently detected by
IceCube -if attributed to extragalactic diffuse events, as it appears likely-
can place the strongest bound on LIV in the neutrino sector, namely delta
=(v^2-1) < O(10^(-18)), corresponding to a QG scale M_QG ~ 10^5 M_Pl (M_QG >~
10^(-4) M_Pl) for a linear (quadratic) LIV, at least for models inducing
superluminal neutrino effects (delta > 0).",1303.5843v2
2013-12-11,Modelling of the optical properties of silver with use of six fitting parameters,"We propose a realistic model of the optical properties of silver, in which
inter-band transition with a threshold energy of ~ 4 eV is described
phenomenologically by an ensemble of oscillators with same damping constant and
a certain distribution of resonant frequencies in the interband transition
threshold to infinity. The contribution of the conduction electrons in the
dielectric function is determined by the Drude formula. The proposed model
actually contains the features of both the Drude-Lorentz model (Raki\'c et al.
1998) and Tauc-Lorentz model (Jian-Hong Qiu et al. 2005). However, unlike these
works proposed model contains only six fitting parameters, with the square root
of the mean square deviation of the absorption coefficient and refractive index
of silver from the experimental values in the range of 0.6 nm - 6.0 nm being of
the order of 0.05.",1312.3100v1
2015-07-16,Lorentz Dispersion Law from classical Hydrogen electron orbits in AC electric field via geometric algebra,"We studied the orbit of an electron revolving around an infinitely massive
nucleus of a large classical Hydrogen atom subject to an AC electric field
oscillating perpendicular to the electron's circular orbit. Using perturbation
theory in geometric algebra, we show that the equation of motion of the
electron perpendicular to the unperturbed orbital plane satisfies a forced
simple harmonic oscillator equation found in Lorentz dispersion law in Optics.
We show that even though we did not introduce a damping term, the initial
orbital position and velocity of the electron results to a solution whose
absorbed energies are finite at the dominant resonant frequency
$\omega=\omega_0$; the electron slowly increases its amplitude of oscillation
until it becomes ionized. We computed the average power absorbed by the
electron both at the perturbing frequency and at the electron's orbital
frequency. We graphed the trace of the angular momentum vector at different
frequencies. We showed that at different perturbing frequencies, the angular
momentum vector traces epicyclical patterns.",1507.04509v1
2018-12-05,Quasi-normal modes of bumblebee wormhole,"In this work, we calculate the quasi-normal frequencies from a bumblebee
traversable wormhole. The bumblebee wormhole model is based on the bumblebee
gravity, which exhibits a spontaneous Lorentz symmetry breaking. Supporting by
the Lorentz violation parameter $\lambda$, this model allows the fulfillment of
the flare-out and energy conditions, granted non-exotic matter to the wormhole.
We analyze the parameters of bumblebee wormhole in order to obtain a
Reege-Wheeler's equation with a bell-shaped potential. We obtain the
quasi-normal modes (QNMs) via the WKB approximation method for both scalar and
gravitational perturbations. All frequencies obtained are stable and the time
domain profiles have decreasing oscillation (damping) profiles for the
bumblebee wormhole.",1812.01798v1
2019-08-20,Damping Mechanisms of the Solar Filament Longitudinal Oscillations in Weak Magnetic Field,"Longitudinal oscillations of solar filament have been investigated via
numerical simulations continuously, but mainly in one dimension (1D), where the
magnetic field line is treated as a rigid flux tube. Whereas those
one-dimensional simulations can roughly reproduce the observed oscillation
periods, implying that gravity is the main restoring force for filament
longitudinal oscillations, the decay time in one-dimensional simulations is
generally longer than in observations. In this paper, we perform a
two-dimensional (2D) non-adiabatic magnetohydrodynamic simulation of filament
longitudinal oscillations, and compare it with the 2D adiabatic case and 1D
adiabatic and non-adiabatic cases. It is found that, whereas both non-adiabatic
processes (radiation and heat conduction) can significantly reduce the decay
time, wave leakage is another important mechanism to dissipate the kinetic
energy of the oscillating filament when the magnetic field is weak so that
gravity is comparable to Lorentz force. In this case, our simulations indicate
that the pendulum model might lead to an error of ~100% in determining the
curvature radius of the dipped magnetic field using the longitudinal
oscillation period when the gravity to Lorentz force ratio is close to unity.",1908.07148v1
2021-04-09,Kinetic instability in inductively oscillatory plasma equilibrium,"A uniform in space, oscillatory in time plasma equilibrium sustained by a
time-dependent current density is analytically and numerically studied
resorting to particle-in-cell simulations. The dispersion relation is derived
from the Vlasov equation for oscillating equilibrium distribution functions,
and used to demonstrate that the plasma has an infinite number of unstable
kinetic modes. This instability represents a new kinetic mechanism for the
decay of the initial mode of infinite wavelength (or equivalently null
wavenumber), for which no classical wave breaking or Landau damping exists. The
relativistic generalization of the instability is discussed. In this regime,
the growth rate of the fastest growing unstable modes scales with
$\gamma_T^{-1/2}$, where $\gamma_T$ is the largest Lorentz factor of the plasma
distribution. This result hints that this instability is not as severely
suppressed for large Lorentz factor flows as purely streaming instabilities.
The relevance of this instability in inductive electric field oscillations
driven in pulsar magnetospheres is discussed.",2104.04490v1
2021-08-17,Application of Herglotz's Variational Principle to Electromagnetic Systems with Dissipation,"This work applies the contact formalism of classical mechanics and classical
field theory, introduced by Herglotz and later developed in the context of
contact geometry, to describe electromagnetic systems with dissipation. In
particular, we study an electron in a non-perfect conductor and a variation of
the cyclotron radiation. In order to apply the contact formalism to a system
governed by the Lorentz force, it is necessary to generalize the classical
electromagnetic gauge and add a term in the Lagrangian. We also apply the
k-contact theory for classical fields to model the behaviour of electromagnetic
fields themselves under external damping. In particular, we show how the theory
describes the evolution of electromagnetic fields in media under some
circumstances. The corresponding Poynting theorem is derived. We discuss its
applicability to the Lorentz dipole model and to a highly resistive dielectric.",2108.07542v3
2022-11-10,Connect the Lorentz Violation to the Glashow Resonance Event,"The recent reported Glashow resonance (GR) event shows a promising prospect
in the test of the Lorentz violation (LV) by the high-energy astrophysical
neutrinos (HANs) around the resonant energy. However, since the production
source and the energy spectra of HANs are uncertain at present, moderate LV
effects may be concealed at the TeV energy-scale. In this paper, we propose the
LV Hamiltonian of a special texture which can lead to the decoupling of
$\nu_{\mu}$ ($\bar{\nu}_{\mu}$). On the base of the decoupling, a noticeable
damping of the GR event rate is shown for the HANs from the source dominated by
$\bar{\nu}_{\mu}$, irrespective of the energy spectra of the HANs at Earth.
Accordingly, the observation of GR events may bring stringent constraints on
the LV and the production mechanism of HANs.",2211.05478v4
2023-05-30,Gravitational traces of bumblebee gravity in metric-affine formalism,"This work explores various manifestations of bumblebee gravity within the
metric-affine formalism. We investigate the impact of the Lorentz violation
parameter, denoted as $X$, on the modification of the Hawking temperature. Our
calculations reveal that as $X$ increases, the values of the Hawking
temperature attenuate. To examine the behavior of massless scalar
perturbations, specifically the quasinormal modes, we employ the WKB method.
The transmission and reflection coefficients are determined through our
calculations. The outcomes indicate that a stronger Lorentz-violating parameter
results in slower damping oscillations of gravitational waves. To comprehend
the influence of the quasinormal spectrum on time-dependent scattering
phenomena, we present a detailed analysis of scalar perturbations in the
time-domain solution. Additionally, we conduct an investigation on shadows,
revealing that larger values of $X$ correspond to larger shadow radii.
Furthermore, we constrain the magnitude of the shadow radii using the EHT
horizon-scale image of $Sgr A^*$. Finally, we calculate both the time delay and
the deflection angle.",2305.18871v2
2005-04-27,Self-consistent radiative effect on relativistic electromagnetic particle acceleration,"We study the radiation damping effect on the relativistic acceleration of
electron-positron plasmas with two-and-half-dimensional particle-in-cell (PIC)
simulation. Particles are accelerated by Poynting flux via the diamagnetic
relativistic pulse accelerator (DRPA), and decelerated by the self-consistently
solved radiation damping force. With $\Omega_{ce}/\omega_{pe}\geq 10$, the
Lorentz factor of the highest energy particles reaches gamma>100, and the
acceleration still continues. The emitted radiation is peaked within few
degrees from the direction of Poynting flux and strongly linearly polarized,
which may be detectable in gamma-ray burst(GRB) observations. We also show that
the DRPA is insensitive to the initial supporting currents.",0504612v2
1995-12-12,Bubble Collisions and Defect Formation in a Damping Environment,"Within the context of a first-order phase transition in the early Universe,
we study the collision process for vacuum bubbles expanding in a plasma. The
effects of the plasma are simulated by introducing a damping term in the
equations of motion for a $U(1)$ global field. We find that Lorentz-contracted
spherically symmetric domain walls adequately describe the overdamped motion of
the bubbles in the thin wall approximation, and study the process of collision
and phase equilibration both numerically and analytically. With an analytical
model for the phase propagation in 1+1 dimensions, we prove that the phase
waves generated in the bubble merging are reflected by the walls of the true
vacuum cavity, giving rise to a long-lived oscillating state that delays the
phase equilibration. The existence of such a state in the 3+1 dimensional model
is then confirmed by numerical simulations, and the consequences for the
formation of vortices in three-bubble collisions are considered.",9512290v1
2005-11-15,Classical Phase Space Density for the Relativistic Hydrogen Atom,"Quantum mechanics is considered to arise from an underlying classical
structure (``hidden variable theory'', ``sub-quantum mechanics''), where
quantum fluctuations follow from a physical noise mechanism. The stability of
the hydrogen ground state can then arise from a balance between Lorentz damping
and energy absorption from the noise. Since the damping is weak, the ground
state phase space density should predominantly be a function of the conserved
quantities, energy and angular momentum.
  A candidate for this phase space density is constructed for ground state of
the relativistic hydrogen problem of a spinless particle. The first excited
states and their spherical harmonics are also considered in this framework. The
analytic expression of the ground state energy can be reproduced, provided
averages of certain products are replaced by products of averages. This
analysis puts forward that quantum mechanics may arise from an underlying
classical level as a slow variable theory, where each new quantum operator
relates to a new, well separated time interval.",0511144v1
2007-01-21,Casimir-Polder forces on excited atoms in the strong atom-field coupling regime,"Based on macroscopic quantum electrodynamics in linear media, we develop a
general theory of the resonant Casimir-Polder force on an excited two-level
atom in the presence of arbitrary linear bodies, with special emphasis on the
strong-coupling regime where reabsorption of an emitted photon can give rise to
(vacuum) Rabi oscillations. We first derive a simple time-independent
expression for the force by using a dressed-state approximation. For initially
single-quantum excited atom-field systems we then study the dynamics of the
force by starting from the Lorentz force and evaluating its average as a
function of time. For strong atom-field coupling, we find that the force may
undergo damped Rabi oscillations. The damping is due to the decay of both the
atomic excitation and the field excitation, and both amplitude and mean value
of the oscillations depend on the chosen initial state.",0701151v2
2010-09-15,A discontinuous Galerkin method for the Vlasov-Poisson system,"A discontinuous Galerkin method for approximating the Vlasov-Poisson system
of equations describing the time evolution of a collisionless plasma is
proposed. The method is mass conservative and, in the case that piecewise
constant functions are used as a basis, the method preserves the positivity of
the electron distribution function and weakly enforces continuity of the
electric field through mesh interfaces and boundary conditions. The performance
of the method is investigated by computing several examples and error estimates
associated system's approximation are stated. In particular, computed results
are benchmarked against established theoretical results for linear advection
and the phenomenon of linear Landau damping for both the Maxwell and Lorentz
distributions. Moreover, two nonlinear problems are considered: nonlinear
Landau damping and a version of the two-stream instability are computed. For
the latter, fine scale details of the resulting long-time BGK-like state are
presented. Conservation laws are examined and various comparisons to theory are
made. The results obtained demonstrate that the discontinuous Galerkin method
is a viable option for integrating the Vlasov-Poisson system.",1009.3046v2
2014-07-31,Plasmons in finite spherical ionic systems,"The challenging question on possible plasmon type excitations in finite ionic
systems is discussed. The related theoretical model is formulated and developed
in order to describe surface and volume plasmons of ion liquid in finite
electrolyte systems. The irradiation of ionic surface plasmon fluctuations is
studied in terms of the Lorentz friction of oscillating charges. The
attenuation of surface plasmons in the ionic sphere is calculated and minimized
with respect to the sphere size. Various regimes of approximation for
description of size effect for damping of ionic plasmons are determined and a
cross-over in damping size-dependence is demonstrated. The most convenient
dimension of finite electrolyte system for energy and information transfer by
usage of ionic dipole plasmons is determined. The overall shift of size effect
to micrometer scale for ions in comparison to nanometer scale for electrons in
metals is found and by several orders red shift of plasmonic resonances in ion
systems is predicted in a wide range of variation depending of ion system
parameters. This convenient opportunity of tuning of resonances differs ionic
plasmons from plasmons in metals where electron concentration was firmly fixed.",1407.8369v2
2017-08-11,On the Small Mass Limit of Quantum Brownian Motion with Inhomogeneous Damping and Diffusion,"We study the small mass limit (or: the Smoluchowski-Kramers limit) of a class
of quantum Brownian motions with inhomogeneous damping and diffusion. For Ohmic
bath spectral density with a Lorentz-Drude cutoff, we derive the
Heisenberg-Langevin equations for the particle's observables using a quantum
stochastic calculus approach. We set the mass of the particle to equal $m =
m_{0} \epsilon$, the reduced Planck constant to equal $\hbar = \epsilon$ and
the cutoff frequency to equal $\Lambda = E_{\Lambda}/\epsilon$, where $m_0$ and
$E_{\Lambda}$ are positive constants, so that the particle's de Broglie
wavelength and the largest energy scale of the bath are fixed as $\epsilon \to
0$. We study the limit as $\epsilon \to 0$ of the rescaled model and derive a
limiting equation for the (slow) particle's position variable. We find that the
limiting equation contains several drift correction terms, the quantum
noise-induced drifts, including terms of purely quantum nature, with no
classical counterparts.",1708.03685v1
2017-06-26,Landau Damping of Beam Instabilities by Electron Lenses,"Modern and future particle accelerators employ increasingly higher intensity
and brighter beams of charged particles and become operationally limited by
coherent beam instabilities. Usual methods to control the instabilities, such
as octupole magnets, beam feedback dampers and use of chromatic effects, become
less effective and insufficient. We show that, in contrast, Lorentz forces of a
low-energy, a magnetically stabilized electron beam, or ""electron lens"", easily
introduces transverse nonlinear focusing sufficient for Landau damping of
transverse beam instabilities in accelerators. It is also important that,
unlike other nonlinear elements, the electron lens provides the frequency
spread mainly at the beam core, thus allowing much higher frequency spread
without lifetime degradation. For the parameters of the Future Circular
Collider, a single conventional electron lens a few meters long would provide
stabilization superior to tens of thousands of superconducting octupole
magnets.",1706.08477v1
2018-12-18,Gravitational quasinormal modes of black holes in Einstein-aether theory,"The local Lorentz violation (LV) in gravity sector should show itself in
derivation of the characteristic quasinormal modes (QNMs) of black hole mergers
from their general relativity case. In this paper, I study QNMs of the
gravitational field perturbations to Einstein-aether black holes and, at first
compare them to those in Schwarzschild black hole, and then some other known LV
gravity theories. By comparing to Schwarzschild black hole, the first kind
aether black holes have larger damping rate and the second ones have lower
damping rate. And they all have smaller real oscillation frequency of QNMs. By
comparing to some other LV theories, the QNMs of the first kind aether black
hole are similar to that of the QED-extension limit of standard model
extension, non-minimal coupling to Einstein's tensor and massive gravity
theories. While as to the second kind aether black hole, they are similar to
those of the noncommutative gravity theories and Einstein-Born-Infeld theories.
These similarities may imply that LV in gravity sector and LV in matter sector
have some intrinsic connections.",1812.07994v1
2023-07-22,Damping of strong GHz waves near magnetars and the origin of fast radio bursts,"We investigate how a GHz radio burst emitted near a magnetar propagates
through its magnetosphere at radii $r=10^7$-$10^9$ cm. Bursts propagating near
the magnetic equator behave as magnetohydrodynamic (MHD) waves if they have
luminosity $L\gg 10^{40}$ erg/s. The waves develop plasma shocks in each
oscillation and dissipate at $r\sim 3 \times 10^8 L_{42}^{-1/4}$ cm. GHz waves
with lower $L$ or propagation directions closer to the magnetic axis do not
obey MHD. Instead, they interact with individual particles, which requires a
kinetic description. The kinetic interaction quickly accelerates particles to
Lorentz factors $10^4$-$10^5$ at the expense of the wave energy, which again
results in strong damping of the wave. In either regime of wave propagation,
MHD or kinetic, the magnetosphere acts as a pillow absorbing the GHz burst and
re-radiating the absorbed energy in X-rays. We conclude that a GHz source
confined in the inner magnetosphere would be blocked by the outer magnetosphere
at practically all relevant luminosities and viewing angles. This result
constrains the origin of observed fast radio bursts (FRBs). We argue that
observed FRBs come from magnetospheric explosions ejecting powerful outflows.",2307.12182v1
2019-06-05,Extended time-dependent Ginzburg-Landau theory,"We formulate the gauge invariant Lorentz covariant Ginzburg-Landau theory
which describes nonstationary regimes: relaxation of a superconducting system
accompanied by eigen oscillations of internal degrees of freedom (Higgs mode
and Goldstone mode), and also forced oscillations under the action of an
external gauge field. The theory describes Lorentz covariant electrodynamics of
superconductors where Anderson-Higgs mechanism occurs, at the same time the
dynamics of conduction electrons remains non-relativistic. It is demonstrated
that Goldstone oscillations cannot be accompanied by oscillations of charge
density and they generate the transverse field only. In addition, we consider
Goldstone modes and features of Anderson-Higgs mechanism in two-band
superconductors. We study dissipative processes, which are caused by movement
of the normal component of electron liquid and violate the Lorentz covariance,
on the examples of the damped oscillations of the order parameter and the
skin-effect for electromagnetic waves. An experimental consequence of the
extended time-dependent Ginzburg-Landau theory regarding the penetration of the
electromagnetic field into a superconductor is proposed.",1906.02097v8
2021-08-10,Superradiant instability of the Kerr-like black hole in Einstein-bumblebee gravity,"An exact Kerr-like solution has been obtained recently in Einstein-bumblebee
gravity model where Lorentz symmetry is spontaneously broken. In this paper, we
investigate the superradiant instability of the Kerr-like black hole under the
perturbation of a massive scalar field. We find the Lorentz breaking parameter
$L$ does not affect the superradiance regime or the regime of the bound states.
However, since $L$ appears in the metric and its effect cannot be erased by
redefining the rotation parameter $\tilde{a}=\sqrt{1+L}a$, it indeed affects
the bound state spectrum and the superradiance. We calculate the bound state
spectrum via the continued-fraction method and show the influence of $L$ on the
maximum binding energy and the damping rate. The superradiant instability could
occur since the superradiance condition and the bound state condition could be
both satisfied. Compared with Kerr black hole, the nature of the superradiant
instability of this black hole depends non-monotonously not only on the
rotation parameter of the black hole $\tilde{a}$ and the product of the black
hole mass $M$ and the field mass $\mu$, but also on the Lorentz breaking
parameter $L$. Through the Monte Carlo method, we find that for $l=m=1$ state
the most unstable mode occurs at $L=-0.79637$, $\tilde{a}/M=0.99884$ and
$M\mu=0.43920$, with the maximum growth rate of the field
$\omega_{I}M=1.676\times10^{-6}$, which is about 10 times of that in Kerr black
hole.",2108.04702v2
2022-07-01,Particle acceleration and radiation reaction in a strongly magnetized rotating dipole,"Abridged. Neutron stars are surrounded by ultra-relativistic particles
efficiently accelerated by ultra strong electromagnetic fields. However so far,
no numerical simulations were able to handle such extreme regimes of very high
Lorentz factors and magnetic field strengths. It is the purpose of this paper
to study particle acceleration and radiation reaction damping in a rotating
magnetic dipole with realistic field strengths typical of millisecond and young
pulsars as well as of magnetars. To this end, we implemented an exact
analytical particle pusher including radiation reaction in the reduced
Landau-Lifshitz approximation where the electromagnetic field is assumed
constant in time and uniform in space during one time step integration. The
position update is performed using a velocity Verlet method. We extensively
tested our algorithm against time independent background electromagnetic fields
like the electric drift in cross electric and magnetic fields and the magnetic
drift and mirror motion in a dipole. Eventually, we apply it to realistic
neutron star environments. We investigated particle acceleration and the impact
of radiation reaction for electrons, protons and iron nuclei plunged around
millisecond pulsars, young pulsars and magnetars, comparing it to situations
without radiation reaction. We found that the maximum Lorentz factor depends on
the particle species but only weakly on the neutron star type. Electrons reach
energies up to $\gamma_e \approx 10^8-10^9$ whereas protons energies up to
$\gamma_p \approx 10^5-10^6$ and iron up to $\gamma \approx 10^4-10^5$. While
protons and irons are not affected by radiation reaction, electrons are
drastically decelerated, reducing their maximum Lorentz factor by 2 orders of
magnitude. We also found that the radiation reaction limit trajectories fairly
agree with the reduced Landau-Lifshitz approximation in almost all cases.",2207.00624v1
2005-10-16,Magnetic vortex dynamics in a 2D easy plane ferromagnet,"In this thesis, we consider the dynamics of vortices in the easy plane
insulating ferromagnet in two dimensions. In addition to the quasiparticle
excitations, here spin waves or magnons, this magnetic system admits a family
of vortex solutions carrying two topological invariants, the winding number or
vorticity, and the polarization. A vortex is approximately described as a
particle moving about the system, endowed with an effective mass and acted upon
by a variety of forces. Classically, the vortex has an inter-vortex potential
energy giving a Coulomb-like force (attractive or repulsive depending on the
relative vortex vorticity), and a gyrotropic force, behaving as a self-induced
Lorentz force, whose direction depends on both topological indices. Expanding
semiclassically about a many-vortex solution, the vortices are quantized by
considering the scattered magnon states, giving a zero point energy correction
and a many-vortex mass tensor. The vortices cannot be described as independent
particles--that is, there are off-diagonal mass terms, such as 1/2 Mij vi vj,
that are non-negligible. This thesis examines the full vortex dynamics in
further detail by evaluating the Feynman-Vernon influence functional, which
describes the evolution of the vortex density matrix after the magnon modes
have been traced out. In addition to the set of forces already known, we find
new damping forces acting both longitudinally and transversely to the vortex
motion. The vortex motion within a collective cannot be entirely separated:
there are damping forces acting on one vortex due to the motion of another. The
effective damping forces have memory effects: they depend not only on the
current motion of the vortex collection but also on the motion history.",0510414v1
2005-11-25,The electrodynamic 2-body problem and the origin of quantum mechanics,"We numerically solve the functional differential equations (FDE's) of
2-particle electrodynamics, using the full electrodynamic force obtained from
the retarded Lienard-Wiechert potentials and the Lorentz force law. In
contrast, the usual formulation uses only the Coulomb force (scalar potential),
reducing the electrodynamic 2-body problem to a system of ordinary differential
equations (ODE's). The ODE formulation is mathematically suspect since FDE's
and ODE's are known to be incompatible; however, the Coulomb approximation to
the full electrodynamic force has been believed to be adequate for physics. We
can now test this long-standing belief by comparing the FDE solution with the
ODE solution, in the historically interesting case of the classical hydrogen
atom. The solutions differ.
  A key qualitative difference is that the full force involves a `delay'
torque. Our existing code is inadequate to calculate the detailed interaction
of the delay torque with radiative damping. However, a symbolic calculation
provides conditions under which the delay torque approximately balances (3rd
order) radiative damping. Thus, further investigations are required, and it was
prematurely concluded that radiative damping makes the classical hydrogen atom
unstable. Solutions of FDE's naturally exhibit an_infinite_ spectrum of
_discrete_ frequencies. The conclusion is that (a) the Coulomb force is_not_ a
valid approximation to the full electrodynamic force, so that (b) the n-body
interaction needs to be reformulated in various current contexts such as
molecular dynamics.",0511235v1
2018-07-02,Thermoplasmonic behavior of semiconductor nanoparticles: A comparison with metals,"A number of applications in nanoplasmonics utilize noble metals, gold (Au)
and silver (Ag), as the materials of choice. However, these materials suffer
from problems of poor thermal and chemical stability accompanied by significant
dissipative losses under high-temperature conditions. In this regard,
semiconductor nanoparticles have attracted attention with their promising
characteristics of highly tunable plasmonic resonances, low ohmic losses and
greater thermochemical stability. Here, we investigate the size-dependent
thermoplasmonic properties of semiconducting silicon and gallium arsenide
nanoparticles to compare them with metallic Au nanoparticles using Mie theory.
To this end, we employ experimentally estimated models of dielectric
permittivity in our computations. Among the various permittivity models for Au,
we further compare the Drude-Lorentz (DL) and the Drude and critical points
(DCP) models. Results show a redshift in the scattering and absorption
resonances for the DL model while the DCP model presents a blueshift. The
dissipative damping in the semiconductor nanoparticles is strongest for the
sharp electric octupole resonances followed by the quadrupole and dipole modes.
However, a reverse order with strongest values for the broad dipole resonance
is observed for the Au nanoparticles. A massive Drude broadening contributes
strongly to the damping of resonances in Au nanoparticles at elevated
temperatures. In contrast, the semiconductor nanoparticles do not exhibit any
significant deterioration in their scattering and absorption resonances at high
temperatures. In combination with low dissipative damping, this makes the
semiconductor nanoparticles better suited for high-temperature applications in
nanoplasmonics wherein the noble metals suffer from excessive heating.",1807.00881v1
2019-02-26,"A fully implicit, scalable, conservative nonlinear relativistic Fokker-Planck 0D-2P solver for runaway electron","Upon application of a sufficiently strong electric field, electrons break
away from thermal equilibrium and approach relativistic speeds. These highly
energetic runaway electrons (MeV) play a significant role in tokamak disruption
physics, and therefore their accurate understanding is essential to develop
reliable mitigation strategies. For this purpose, we have developed a fully
implicit solver for the 0D-2P (i.e., including two momenta coordinates)
relativistic nonlinear Fokker-Planck equation (rFP). As in earlier implicit rFP
studies (NORSE, CQL3D), electron-ion interactions are modeled using the Lorentz
operator, and synchrotron damping using the Abraham-Lorentz-Dirac reaction
term. However, our implementation improves on these earlier studies by 1)
ensuring exact conservation properties for electron collisions, 2) strictly
preserving positivity, and 3) being scalable algorithmically and in parallel.
Key to our proposed approach is an efficient multigrid preconditioner for the
linearized rFP equation, a multigrid elliptic solver for the Braams-Karney
potentials [Braams and Karney, Phys. Rev. Lett. 59, 16 (1987)], and a novel
adaptive technique to determine the associated boundary values. We verify the
accuracy and efficiency of the proposed scheme with numerical results ranging
from small electric-field electrical conductivity measurements to the accurate
reproduction of runaway tail dynamics when strong electric fields are applied.",1902.10241v3
2021-04-09,New binary pulsar constraints on Einstein-æther theory after GW170817,"The timing of millisecond pulsars has long been used as an exquisitely
precise tool for testing the building blocks of general relativity, including
the strong equivalence principle and Lorentz symmetry. Observations of binary
systems involving at least one millisecond pulsar have been used to place
bounds on the parameters of Einstein-{\ae}ther theory, a gravitational theory
that violates Lorentz symmetry at low energies via a preferred and dynamical
time threading of the spacetime manifold. However, these studies did not cover
the region of parameter space that is still viable after the recent bounds on
the speed of gravitational waves from GW170817/GRB170817A. The restricted
coverage was due to limitations in the methods used to compute the pulsar
sensitivities, which parameterize violations of the strong-equivalence
principle in these systems. We extend here the calculation of pulsar
sensitivities to the parameter space of Einstein-{\ae}ther theory that remains
viable after GW170817/GRB170817A. We show that observations of the damping of
the period of quasi-circular binary pulsars and of the triple system PSR
J0337+1715 further constrain the viable parameter space by about an order of
magnitude over previous constraints.",2104.04596v2
2014-07-31,Propagation of collective surface plasmons in 1D periodic ionic structure,"The propagation of the collective surface plasmons, called
plasmon-polaritons, in infinite equidistant ionic sphere chain has been
analyzed. The ideal cancellation of irradiative losses of these ionic
excitations in the chain is demonstrated by inclusion of appropriately retarded
near-, medium and far-field components of dipole interaction between spheres in
the chain. It is proved that the Lorentz friction losses in each sphere are
completely compensated by the energy income from the rest of the chain for a
wide sector of the plasmon-polariton wave vector domain. There is shown that
the damping of plasmon-polariton is reduced to only residual Ohmic losses much
lower than irradiation losses for the separate electrolyte sphere. The
self-frequencies and the group velocities of plasmon-polaritons for
longitudinal and transversal (with respect to the chain orientation)
polarizations are determined and assessed for various ion and electrolyte
parameters. It is proved that there exist weakly damped self-modes of
plasmon-polaritons in the chain for which the propagation range is limited by
relatively small Ohmic losses only. Completely undamped collective waves are
also described in the case of the presence of persistent external excitation of
some fragment of the chain. The possibility of application of the
plasmon-polariton model to describe the so-called saltatory conduction in
periodically myelinated nerve axons is preliminarily discussed.",1407.8419v2
2016-01-01,Atmospheric Circulation of Hot Jupiters: Dayside-Nightside Temperature Differences,"The full-phase infrared light curves of low-eccentricity hot Jupiters show a
trend of increasing dayside-to-nightside brightness temperature difference with
increasing equilibrium temperature. Here we present a three-dimensional model
that explains this relationship, in order to shed insight on the processes that
control heat redistribution in tidally-locked planetary atmospheres. This
three-dimensional model combines predictive analytic theory for the atmospheric
circulation and dayside-nightside temperature differences over a range of
equilibrium temperature, atmospheric composition, and potential frictional drag
strengths with numerical solutions of the circulation that verify this analytic
theory. This analytic theory shows that the longitudinal propagation of waves
mediates dayside-nightside temperature differences in hot Jupiter atmospheres,
analogous to the wave adjustment mechanism that regulates the thermal structure
in Earth's tropics. These waves can be damped in hot Jupiter atmospheres by
either radiative cooling or potential frictional drag. This frictional drag
would likely be caused by Lorentz forces in a partially ionized atmosphere
threaded by a background magnetic field, and would increase in strength with
increasing temperature. Additionally, the amplitude of radiative heating and
cooling increases with increasing temperature, and hence both radiative
heating/cooling and frictional drag damp waves more efficiently with increasing
equilibrium temperature. Radiative heating and cooling play the largest role in
controlling dayside-nightside temperature temperature differences in both our
analytic theory and numerical simulations, with frictional drag only important
if it is stronger than the Coriolis force. As a result, dayside-nightside
temperature differences in hot Jupiter atmospheres increase with increasing
stellar irradiation and decrease with increasing pressure.",1601.00069v2
2021-04-12,Thermal Radiation Equilibrium: (Nonrelativistic) Classical Mechanics versus (Relativistic) Classical Electrodynamics,"Energy equipartition is appropriate only for nonrelativistic classical
mechanics, but has only limited relevance for a relativistic theory such as
classical electrodynamics. In this article, we discuss harmonic-oscillator
thermal equilibrium from three different perspectives. First, we contrast the
thermal equilibrium of nonrelativistic mechanical oscillators (where point
collisions are allowed and frequency is irrelevant) with the equilibrium of
relativistic radiation modes (where frequency is crucial). The Rayleigh-Jeans
law appears from applying a dipole-radiation approximation to impose the
nonrelativistic mechanical equilibrium on the radiation spectrum. In this
discussion, we note the possibility of zero-point energy for relativistic
radiation, which possibility does not arise for nonrelativistic
classical-mechanical systems. Second, we turn to a simple electromagnetic model
of a harmonic oscillator and show that the oscillator is fully in radiation
equilibrium (which involves all radiation multipoles, dipole, quadrupole, etc.)
with classical electromagnetic zero-point radiation, but is not in equilibrium
with the Rayleigh-Jeans spectrum. Finally, we discuss the contrast between the
flexibility of nonrelativistic mechanics with its arbitrary potential functions
allowing separate scalings for length, time, and energy, with the
sharply-controlled behavior of relativistic classical electrodynamics with its
single scaling connecting together the scales for length, time, and energy. It
is emphasized that within classical physics, energy-sharing, velocity-dependent
damping is associated with the low-frequency, nonrelativistic part of the
Planck thermal radiation spectrum, whereas acceleration-dependent radiation
damping is associated with the high-frequency adiabatically-invariant and
Lorentz-invariant part of the spectrum corresponding to zero-point radiation.",2104.05789v1
2023-11-22,Narrow spectra of repeating fast radio bursts: A magnetospheric origin,"Fast radio bursts (FRBs) can present a variety of polarization properties,
and some of them have narrow spectra. We study spectral properties from
perspectives of intrinsic radiation mechanisms and absorption during the waves
propagating in the magnetosphere. The intrinsic radiation mechanisms are
considered by invoking quasi-periodic bunch distribution and perturbations on
charged bunches moving on curved trajectories. The narrow-band emission likely
reflects some quasi-periodic structure on the bulk of bunches, which may be due
to quasi-periodically sparking in a ``gap'' or quasi-monochromatic Langmuir
waves. A sharp spike would appear at the spectrum if the perturbations can
induce a monochromatic oscillation of bunches, however, it is hard to create a
narrow spectrum because the Lorentz factor has large fluctuations so that the
spike disappears. Both the bunching mechanism and perturbations scenarios share
the same polarization properties with a uniformly distributed bulk of bunches.
We investigate absorption effects including Landau damping and curvature
self-absorption in the magnetosphere, which are significant at low frequencies.
Subluminous O-mode photons can not escape from the magnetosphere due to the
Landau damping, leading to a height-dependent lower frequency cut-off. Spectra
can be narrow when the frequency cut-off is close to the characteristic
frequency of curvature radiation, while such conditions can only be met
sometimes. The spectral index is 5/3 at low-frequency bands due to the
curvature self-absorption but not as steep as the observations. The intrinsic
radiation mechanisms are more likely to generate the observed narrow spectra of
FRBs rather than the absorption effects.",2311.13114v2
2005-01-14,Analytical studies of particle dynamics in bending waves in planetary rings,"Particles inside a planetary ring are subject to forcing due to the central
planet, moons in inclined orbits, self-gravity of the ring and other forces due
to radiation drag, collisional effects and Lorentz force due to magnetic field
of the planet. We write down the equations of motion of a single particle
inside the ring and solve them analytically. We find that the importance of the
shear caused by variation of the radial velocity component with local vertical
direction cannot be ignored and it may be responsible for damping of the
bending waves in planetary rings as observed by the Voyager data. We present
the wave profile resulting from the dissipation. We estimate that the surface
mass density of the C ring to be of the order of $\sigma \sim 1.2-1.6$gm
cm$^{-2}$, and the height $h \sim 2.2-2.4$m. These theoretical results are in
agreement with observations.",0501286v1
2006-02-18,Optical phonons in new ordered perovskite Sr2Cu(Re0.69Ca0.31) Oy system observed by infrared reflectance spectroscopy,"We report infrared reflectivity spectra for a new correlated cupric oxide
system Sr2Cu(Re0.69Ca0.31)Oy with y ~ 0.6 at several temperatures ranging
between 8 and 380 K. The reflectivity spectrum at 300 K comprises of several
optical phonons. A couple of residual bands located around 315 and 653 cm-1
exhibit exceptionally large intensity as compared to the other ones. The
overall reflectivity spectrum lifts up slightly with increasing temperature.
The energy and damping factor of transverse-optical phonons are determined by
fitting the imaginary dielectric constant by Lorentz oscillator model and
discussed as a function of temperature in terms of lattice anharmonicity.",0602438v1
1995-04-12,STABLE CLOCKS AND GENERAL RELATIVITY,"We survey the role of stable clocks in general relativity. Clock comparisons
have provided important tests of the Einstein Equivalence Principle, which
underlies metric gravity. These include tests of the isotropy of clock
comparisons (verification of local Lorentz invariance) and tests of the
homogeneity of clock comparisons (verification of local position invariance).
Comparisons of atomic clocks with gravitational clocks test the Strong
Equivalence Principle by bounding cosmological variations in Newton's constant.
Stable clocks also play a role in the search for gravitational radiation:
comparision of atomic clocks with the binary pulsar's orbital clock has
verified gravitational-wave damping, and phase-sensitive detection of waves
from inspiralling compact binaries using laser interferometric gravitational
observatories will facilitate extraction of useful source information from the
data. Stable clocks together with general relativity have found important
practical applications in navigational systems such as GPS.",9504017v1
2005-04-19,Was Einstein Right? Testing Relativity at the Centenary,"We review the experimental evidence for Einstein's special and general
relativity. A variety of high precision null experiments verify the weak
equivalence principle and local Lorentz invariance, while gravitational
redshift and other clock experiments support local position invariance.
Together these results confirm the Einstein Equivalence Principle which
underlies the concept that gravitation is synonymous with spacetime geometry,
and must be described by a metric theory. Solar system experiments that test
the weak-field, post-Newtonian limit of metric theories strongly favor general
relativity. The Binary Pulsar provides tests of gravitational-wave damping and
of strong-field general relativity. Recently discovered binary pulsar systems
may provide additional tests. Future and ongoing experiments, such as the
Gravity Probe B Gyroscope Experiment, satellite tests of the Equivalence
principle, and tests of gravity at short distance to look for extra spatial
dimensions could constrain extensions of general relativity. Laser
interferometric gravitational-wave observatories on Earth and in space may
provide new tests of gravitational theory via detailed measurements of the
properties of gravitational waves.",0504086v1
2006-05-12,Perturbations and quasi-normal modes of black holes in Einstein-Aether theory,"We develop a new method for calculation of quasi-normal modes of black holes,
when the effective potential, which governs black hole perturbations, is known
only numerically in some region near the black hole. This method can be applied
to perturbations of a wide class of numerical black hole solutions. We apply it
to the black holes in the Einstein-Aether theory, a theory where general
relativity is coupled to a unit time-like vector field, in order to observe
local Lorentz symmetry violation. We found that in the non-reduced
Einstein-Aether theory, real oscillation frequency and damping rate of
quasi-normal modes are larger than those of Schwarzschild black holes in the
Einstein theory.",0605082v5
1999-06-09,Light Cone Condition for a Thermalized QED Vacuum,"Within the QED effective action approach, we study the propagation of
low-frequency light at finite temperature. Starting from a general effective
Lagrangian for slowly varying fields whose structure is solely dictated by
Lorentz covariance and gauge invariance, we derive the light cone condition for
light propagating in a thermalized QED vacuum. As an application, we calculate
the velocity shifts, i.e., refractive indices of the vacuum, induced by
thermalized fermions to one loop. We investigate various temperature domains
and also include a background magnetic field. While low-temperature effects to
one loop are exponentially damped by the electron mass, there exists a maximum
velocity shift of $-\delta v^2_{max}=\alpha/(3\pi)$ in the
intermediate-temperature domain $T\sim m$.",9906303v3
2005-03-18,Impact parameter profile of synchrotron radiation,"The horizontal impact parameter profile of synchrotron radiation, for fixed
vertical angle of the photon, is calculated. This profile is observed through
an astigmatic optical system, horizontally focused on the electron trajectory
and vertically focused at infinity. It is the product of the usual angular
distribution of synchrotron radiation, which depends on the vertical angle
$\psi$, and the profile function of a caustic staying at distance $\bcl =
(\gamma^{-2} + \psi^2) \RB/2 $ from the orbit circle, $\RB$ being the bending
radius and $\gamma$ the Lorentz factor. The {\it classical impact parameter}
$\bcl$ is connected to the Schott term of radiation damping theory. The caustic
profile function is an Airy function squared. Its fast oscillations allow a
precise determination of the horizontal beam width.",0503182v1
1998-03-12,Berry's Phase in the Presence of a Stochastically Evolving Environment: A Geometric Mechanism for Energy-Level Broadening,"The generic Berry phase scenario in which a two-level system is coupled to a
second system whose dynamical coordinate is slowly-varying is generalized to
allow for stochastic evolution of the slow system. The stochastic behavior is
produced by coupling the slow system to a heat resevoir which is modeled by a
bath of harmonic oscillators initially in equilibrium at temperature T, and
whose spectral density has a bandwidth which is small compared to the
energy-level spacing of the fast system. The well-known energy-level shifts
produced by Berry's phase in the fast system, in conjunction with the
stochastic motion of the slow system, leads to a broadening of the fast system
energy-levels. In the limit of strong damping and sufficiently low temperature,
we determine the degree of level-broadening analytically, and show that the
slow system dynamics satisfies a Langevin equation in which Lorentz-like and
electric-like forces appear as a consequence of geometrical effects. We also
determine the average energy-level shift produced in the fast system by this
mechanism.",9803026v1
2007-10-25,Confronting the trans-Planckian question of inflationary cosmology with dissipative effects,"We provide a class of QFTs which exhibit dissipation above a threshold
energy, thereby breaking Lorentz invariance. Unitarity is preserved by coupling
the fields to additional degrees of freedom (heavy fields) which introduce the
rest frame. Using the Equivalence Principle, we define these theories in
arbitrary curved spacetime. We then confront the trans-Planckian question of
inflationary cosmology. When dissipation increases with the energy, the quantum
field describing adiabatic perturbations is completely damped at the onset of
inflation. However it still exists as a composite operator made with the
additional fields. And when these are in their ground state, the standard power
spectrum obtains if the threshold energy is much larger that the Hubble
parameter. In fact, as the energy redshifts below the threshold, the composite
operator behaves as if it were a free field endowed with standard vacuum
fluctuations. The relationship between our models and the Brane World scenarios
studied by Libanov and Rubakov displaying similar effects is discussed. The
signatures of dissipation will be studied in a forthcoming paper.",0710.4664v2
2009-03-15,Gauge Invariant Summation of All QCD Virtual Gluon Exchanges,"The interpretation of virtual gluons as ghosts in the non-linear gluonic
structure of QCD permits the formulation and realization of a manifestly
gauge-invariant and Lorentz covariant theory of interacting quarks/anti-quarks,
for all values of coupling. The simplest example of quark/anti-quark scattering
in a high-energy, quenched, eikonal model at large coupling is shown to be
expressible as a set of finite, local integrals which may be evaluated
numerically; and before evaluation, it is clear that the result will be
dependent only on, and is damped by increasing momentum transfer, while
displaying physically-reasonable color dependence in a manner underlying the
MIT Bag Model and an effective, asymptotic freedom. A similar but more
complicated integral will result from all possible gluonic-radiative
corrections to this simplest eikonal model. Our results are compatible with an
earlier, field-strength analysis of Reinhardt et al.",0903.2644v2
2009-06-08,A Tail of a Quark in N=4 SYM,"We study the dynamics of a `composite' or `dressed' quark in strongly-coupled
large-N_c N=4 super-Yang-Mills, making use of the AdS/CFT correspondence. We
show that the standard string dynamics nicely captures the physics of the quark
and its surrounding non-Abelian field configuration, making it possible to
derive a relativistic equation of motion that incorporates the effects of
radiation damping. From this equation one can deduce a non-standard dispersion
relation for the composite quark, as well as a Lorentz covariant formula for
its rate of radiation. We explore the consequences of the equation in a few
simple examples.",0906.1592v2
2010-03-28,Undamped energy transport by collective surface plasmon oscillations along metallic nanosphere chain,"The random-phase-approximation semiclassical scheme for description of
plasmon excitations in large metallic nanospheres (with radius 10--100 nm) is
developed for a case of presence of dynamical electric field. The spectrum of
plasmons in metallic nanosphere is determined including both surface and volume
type excitations and their mutual connections. It is demonstrated that only
surface plasmons of dipole type can be excited by a homogeneous dynamical
electric field. The Lorentz friction due to irradiation of e-m energy by
plasmon oscillations is analysed with respect to the sphere dimension. The
resulting shift of resonance frequency due to plasmon damping is compared with
experimental data for various sphere radii. Collective of wave-type
oscillations of surface plasmons in long chains of metallic spheres are
described. The undamped region of propagation of plasmon waves along the chain
is found in agreement with some previous numerical simulations.",1003.5389v1
2012-06-16,On the spectrum of the pulsed gamma-ray emission from 10MeV to 400GeV of the Crab pulsar,"In the present paper a self-consistent theory, interpreting the VERITAS
observations of the very high energy pulsed emission from the Crab pulsar is
considered. The photon spectrum between 10MeV and 400GeV can be described by
two power-law functions with the spectral indexes equal to 2 and 3.8. The
source of the pulsed emission above 10MeV is assumed to be the synchrotron
radiation, which is generated near the light cylinder during the quasi-linear
stage of the cyclotron instability. The emitting particles are the primary beam
electrons with the Lorentz factors up to $10^{9}$. Such high energies by beam
particles is supposed to be reached due to Landau damping of the centrifugally
induced Langmuir waves. This mechanism provides simultaneous generation of low
(radio) and high energy (10MeV-400GeV) emission on the light cylinder scales,
in one location of the pulsar magnetosphere.",1206.3660v2
2012-06-18,Quantum Breathing of an Impurity in a One-dimensional Bath of Interacting Bosons,"By means of time-dependent density-matrix renormalization-group (TDMRG) we
are able to follow the real-time dynamics of a single impurity embedded in a
one-dimensional bath of interacting bosons. We focus on the impurity breathing
mode, which is found to be well-described by a single oscillation frequency and
a damping rate. If the impurity is very weakly coupled to the bath, a
Luttinger-liquid description is valid and the impurity suffers an
Abraham-Lorentz radiation-reaction friction. For a large portion of the
explored parameter space, the TDMRG results fall well beyond the
Luttinger-liquid paradigm.",1206.3984v1
2012-07-02,Second order equation of motion for electromagnetic radiation back-reaction,"We take the viewpoint that the physically acceptable solutions of the
Lorentz--Dirac equation for radiation back-reaction are actually determined by
a second order equation of motion, the self-force being given as a function of
spacetime location and velocity. We propose three different methods to obtain
this self-force function. For two example systems, we determine the second
order equation of motion exactly in the nonrelativistic regime via each of
these three methods, the three methods leading to the same result. We reveal
that, for both systems considered, back-reaction induces a damping proportional
to velocity and, in addition, it decreases the effect of the external force.",1207.0428v6
2012-07-17,New complete orthonormal sets of exponential type orbitals in standard convention and their origin,"In standard convention, the new complete orthonrmal sets of exponential type
orbitals (ETOs) are introduced as functions of the complex or real spherical
harmonics and modified and -generalized Laguerre polynomials (MPLs and GLPs),
where, and is the noninteger or integer (for) frictional quantum number. It is
shown that the origin of the ETOs, MLPs and GLPs is the self-frictional quantum
forces which are analog of radiation damping or self-frictional forces
introduced by Lorentz in classical electrodynamics. The relations for the
quantum self-frictional potentials in terms of ETOs, MLPs and GLPs,
respectively, are established. We note that, in the case of disappearing
frictional forces, the ETOs are reduces to the oringers wave functions for the
hydrogen-like atoms in standard convention and, therefore, become the
noncomplete.",1207.4390v1
2013-01-14,Universal Properties of the Higgs Resonance in (2+1)-Dimensional U(1) Critical Systems,"We present spectral functions for the magnitude squared of the order
parameter in the scaling limit of the two-dimensional superfluid to Mott
insulator quantum phase transition at constant density, which has emergent
particle-hole symmetry and Lorentz invariance. The universal functions for the
superfluid, Mott insulator, and normal liquid phases reveal a low-frequency
resonance which is relatively sharp and is followed by a damped oscillation (in
the first two phases only) before saturating to the quantum critical plateau.
The counterintuitive resonance feature in the insulating and normal phases
calls for deeper understanding of collective modes in the strongly coupled
(2+1)-dimensional relativistic field theory. Our results are derived from
analytically continued correlation functions obtained from path-integral Monte
Carlo simulations of the Bose-Hubbard model.",1301.3139v2
2013-03-08,Polariton excitation in epsilon-near-zero slabs: transient trapping of slow light,"We numerically investigate the propagation of a spatially localized and
quasi-monochromatic electromagnetic pulse through a slab with Lorentz
dielectric response in the epsilon-near-zero regime, where the real part of the
permittivity vanishes at the pulse carrier frequency. We show that the pulse is
able to excite a set of virtual polariton modes supported by the slab, the
excitation undergoing a generally slow damping due to absorption and radiation
leakage. Our numerical and analytical approaches indicate that in its transient
dynamics the electromagnetic field displays the very same enhancement of the
field component perpendicular to the slab, as in the monochromatic regime. The
transient trapping is inherently accompanied by a significantly reduced group
velocity ensuing from the small dielectric permittivity, thus providing a novel
platform for achieving control and manipulation of slow light.",1303.2057v1
2013-06-14,Electron dynamics controlled via self-interaction,"The dynamics of an electron in a strong laser field can be significantly
altered by radiation reaction. This usually results in a strongly damped
motion, with the electron losing a large fraction of its initial energy. Here
we show that the electron dynamics in a bichromatic laser pulse can be
indirectly controlled by a comparatively small radiation reaction force through
its interplay with the Lorentz force. By changing the relative phase between
the two frequency components of the bichromatic laser field, an
ultrarelativistic electron bunch colliding head-on with the laser pulse can be
deflected in a controlled way, with the deflection angle being independent of
the initial electron energy. The effect is predicted to be observable with
laser powers and intensities close to those of current state-of-the-art
petawatt laser systems.",1306.3328v3
2015-02-02,Evolution of Higgs mode in a Fermion Superfluid with Tunable Interactions,"In this letter we present a coherent picture for the evolution of Higgs mode
in both neutral and charged $s$-wave fermion superfluids, as the strength of
attractive interaction between fermions increases from the BCS to the BEC
regime. In the case of neutral fermionic superfluid, such as ultracold
fermions, the Higgs mode is pushed to higher energy while at the same time,
gradually loses its spectral weight as interaction strength increases toward
the BEC regime, because the system is further tuned away from Lorentz
invariance. On the other hand, when damping is taken into account, Higgs mode
is significantly broadened due to coupling to phase mode in the whole BEC-BCS
crossover. In the charged case of electron superconductor, the Anderson-Higgs
mechanism gaps out the phase mode and suppresses the coupling between the Higgs
and the phase modes, and consequently, stabilizes the Higgs mode.",1502.00431v1
2015-08-31,The synchrotron-self-Compton spectrum of relativistic blast waves at large Y,"Recent analyses of multiwavelength light curves of gamma-ray bursts
afterglows point to values of the magnetic turbulence well below the canonical
$\sim1\,$\% of equipartition, in agreement with theoretical expectations of a
micro-turbulence generated in the shock precursor, which then decays downstream
of the shock front through collisionless damping. As a direct consequence, the
Compton parameter $Y$ can take large values in the blast. In the presence of
decaying micro-turbulence and/or as a result of the Klein-Nishina suppression
of inverse Compton cooling, the $Y$ parameter carries a non-trivial dependence
on the electron Lorentz factor, which modifies the spectral shape of the
synchrotron and inverse Compton components. This paper provides detailed
calculations of this synchrotron-self-Compton spectrum in this large $Y$
regime, accounting for the possibility of decaying micro-turbulence. It
calculates the expected temporal and spectral indices $\alpha$ and $\beta$
customarily defined by $F_\nu\,\propto\,t_{\rm obs}^{-\alpha}\nu^{-\beta}$ in
various spectral domains. This paper also makes predictions for the very high
energy photon flux; in particular, it shows that the large $Y$ regime would
imply a detection rate of gamma-ray bursts at $>10\,$GeV several times larger
than currently anticipated.",1508.07830v1
2020-07-28,Pair emission from a relativistic domain wall in antiferromagnets,"Magnon emission and excitation by a relativistic domain wall at a constant
velocity in antiferromagnet is theoretically studied. A pair emission due to a
quadratic magnon coupling is shown to be dominant. The emission corresponds in
the comoving frame to a vacuum polarization induced by a zero-energy
instability of the Lorentz-boosted anomalous response function. The emission
rate is sensitive to the magnon dispersion and wall profile, and is
significantly enhanced for a thin wall with velocity close to the effective
light velocity. The Ohmic damping constant due to magnon excitation at low
velocity is calculated.",2007.13939v1
2014-03-28,The Confrontation between General Relativity and Experiment,"The status of experimental tests of general relativity and of theoretical
frameworks for analyzing them are reviewed and updated. Einstein's equivalence
principle (EEP) is well supported by experiments such as the Eotvos experiment,
tests of local Lorentz invariance and clock experiments. Ongoing tests of EEP
and of the inverse square law are searching for new interactions arising from
unification or quantum gravity. Tests of general relativity at the
post-Newtonian level have reached high precision, including the light
deflection, the Shapiro time delay, the perihelion advance of Mercury, the
Nordtvedt effect in lunar motion, and frame-dragging. Gravitational-wave
damping has been detected in an amount that agrees with general relativity to
better than half a percent using the Hulse-Taylor binary pulsar, and a growing
family of other binary pulsar systems is yielding new tests, especially of
strong-field effects. Current and future tests of relativity will center on
strong gravity and gravitational waves.",1403.7377v1
2017-04-21,Magnetic field influence on the early time dynamics of heavy-ion collisions,"In high energy heavy-ion collisions the magnetic field is very strong right
after the nuclei penetrate each other and a non-equilibrium system of quarks
and gluons builds up. Even though quarks might not be very abundant initially,
their dynamics must necessarily be influenced by the Lorentz force. Employing
the 3+1d partonic cascade BAMPS we show that the circular Larmor movement of
the quarks leads to a strong positive anisotropic flow of quarks at very soft
transverse momenta. We explore the regions where the effect is visible, and
explicitly show how collisions damp the effect. As a possible application we
look at photon production from the flowing non-equilibrium medium.",1704.06505v1
2012-01-19,New development in theory of Laguerre polynomials,"The new complete orthonormal sets of -Laguerre type polynomials (-LTP,) are
suggested. Using Schr\""odinger equation for complete orthonormal sets of
-exponential type orbitals (-ETO) introduced by the author, it is shown that
the origin of these polynomials is the centrally symmetric potential which
contains the core attraction potential and the quantum frictional potential of
the field produced by the particle itself. The quantum frictional forces are
the analog of radiation damping or frictional forces suggested by Lorentz in
classical electrodynamics. The new -LTP are complete without the inclusion of
the continuum states of hydrogen like atoms. It is shown that the nonstandard
and standard conventions of -LTP and their weight functions are the same. As an
application, the sets of infinite expansion formulas in terms of -LTP and
L-Generalized Laguerre polynomials (L-GLP) for atomic nuclear attraction
integrals of Slater type orbitals (STO) and Coulomb-Yukawa like correlated
interaction potentials (CIP) with integer and noninteger indices are obtained.
The arrange and rearranged power series of a general power function are also
investigated. The convergence of these series is tested by calculating concrete
cases for arbitrary values of parameters of orbitals and power function.",1201.4314v1
2016-12-02,Two-fluid model of the pulsar magnetosphere represented as an axisymmetric force-free dipole,"Based on the exact dipolar solution of the pulsar equation the
self-consistent two-fluid model of the pulsar magnetosphere is developed. We
concentrate on the low-mass limit of the model, taking into account the
radiation damping. As a result, we obtain the particle distributions sustaining
the dipolar force-free configuration of the pulsar magnetosphere in case of a
slight velocity shear of the electron and positron components. Over most part
of the force-free region, the particles follow the poloidal magnetic field
lines, with the azimuthal velocities being small. Close to the Y-point,
however, the particle motion is chiefly azimuthal and the Lorentz-factor grows
unrestrictedly. This may result in the very-high-energy emission from the
vicinity of the Y-point and may also imply the magnetocentrifugal formation of
a jet. As for the first-order quantities, the longitudinal accelerating
electric field is found to change the sign, hinting at coexistence of the polar
and outer gaps. Besides that, the components of the plasma conductivity tensor
are derived and the low-mass analogue of the pulsar equation is formulated as
well.",1612.00590v2
2017-12-16,Ternary generalization of Pauli's principle and the Z6-graded algebras,"We show how the discrete symmetries $Z_2$ and $Z_3$ combined with the
superposition principle result in the $SL(2, {\bf C})$-symmetry of quantum
states. The role of Pauli's exclusion principle in the derivation of the SL(2,
C) symmetry is put forward as the source of the macroscopically observed
Lorentz symmetry, then it is generalized for the case of the Z3 grading
replacing the usual Z2 grading, leading to ternary commutation relations. We
discuss the cubic and ternary generalizations of Grassmann algebra. Invariant
cubic forms are introduced, and their symmetry group is shown to be the
$SL(2,C)$ group The wave equation generalizing the Dirac operator to the
Z3-graded case is constructed. Its diagonalization leads to a sixth-order
equation. The solutions cannot propagate because their exponents always contain
non-oscillating real damping factor. We show how certain cubic products can
propagate nevertheless. The model suggests the origin of the color SU(3)
symmetry.",1712.10006v1
2019-02-08,Quantitative analysis of the interaction between a dc SQUID and an integrated micromechanical doubly clamped cantilever,"Based on the superconducting quantum interference device (SQUID) equations
described by the resistively- and capacitively-shunted junction model coupled
to the equation of motion of a damped harmonic oscillator, we provide
simulations to quantitatively describe the interaction between a dc SQUID and
an integrated doubly clamped cantilever. We have chosen to investigate an
existing experimental configuration and have explored the motion of the
cantilever and the reaction of the SQUID as a function of the voltage-flux
$V(\Phi)$ characteristics. We clearly observe the Lorentz force back-action
interaction and demonstrate how a sharp transition state drives the system into
a nonlinear-like regime, and modulates the cantilever displacement amplitude,
simply by tuning the SQUID parameters.",1902.03199v1
2019-03-02,Regularities in the transformation of the oscillating decay rate in moving unstable quantum systems,"Decay laws of moving unstable quantum systems with oscillating decay rates
are analyzed over intermediate times. The transformations of the decay laws at
rest and of the intermediate times at rest, which are induced by the change of
reference frame, are obtained by decomposing the modulus of the survival
amplitude at rest into purely exponential and exponentially damped oscillating
modes. The mass distribution density is considered to be approximately
symmetric with respect to the mass of resonance. Under determined conditions,
the modal decay widths at rest, $\Gamma_j$, and the modal frequencies of
oscillations at rest, $\Omega_j$, reduce regularly, $\Gamma_j/\gamma$ and
$\Omega_j/\gamma$, in the laboratory reference frame. Consequently, the
survival probability at rest, the intermediate times at rest and, if the
oscillations are periodic, the period of the oscillations at rest transform
regularly in the laboratory reference frame according to the same time scaling,
over a determined time window. The time scaling reproduces the relativistic
dilation of times if the mass of resonance is considered to be the effective
mass at rest of the moving unstable quantum system with relativistic Lorentz
factor $\gamma$.",1903.01441v1
2019-08-29,Observations of Electromagnetic Electron Holes and Evidence of Cherenkov Whistler Emission,"We report observations of electromagnetic electron holes (EHs). We use
multi-spacecraft analysis to quantify the magnetic field contributions of three
mechanisms: the Lorentz transform, electron drift within the EH, and Cherenkov
emission of whistler waves. The first two mechanisms account for the observed
magnetic fields for slower EHs, while for EHs with speeds approaching half the
electron Alfv\'en speed, whistler waves excited via the Cherenkov mechanism
dominate the perpendicular magnetic field. The excited whistlers are
kinetically damped and typically confined within the EHs.",1908.11198v2
2020-08-18,The Drude-Smith Model for Conductivity: de novo Derivation and Interpretation,"The Drude-Smith model successfully describes the frequency and phase-resolved
electrical conductivity data for a surprisingly broad range of systems,
especially in the terahertz region. Still, its interpretation is unclear since
its original derivation is flawed. We use an intuitive physical framework to
derive the Drude-Smith formula for systems where microscopically free charges
are accumulated on a mesoscopic scale by localized scatterers. Within this
framework, the model allows us to quantify the microscopic momentum relaxation
time of the charges and the fraction of mesoscopically localized charges in
addition to the direct current limit of the conductivity. We show that the
Drude-Smith model is unique among different Drude-Lorentz models because the
relaxation time of the free carriers also determines the frequency and damping
of the resonance of the bound charges.",2008.07913v2
2022-11-01,Modeling of three-dimensional betatron oscillation and radiation reaction in plasma accelerators,"Betatron oscillation is a commonly known phenomenon in laser or beam driven
plasma wakefield accelerators. In the conventional model, the plasma wake
provides a linear focusing force to a relativistic electron, and the electron
oscillates in one transverse direction with the betatron frequency proportional
to $1/\sqrt{\gamma}$, where $\gamma$ is the Lorentz factor of the electron. In
this work, we extend this model to three-dimensional by considering the
oscillation in two transverse and one longitudinal directions. The long-term
equations, with motion in the betatron time scale averaged out, are obtained
and compared with the original equations by numerical methods. In addition to
the longitudinal and transverse damping due to radiation reaction which has
been found before, we show phenomena including the longitudinal phase drift,
betatron phase shift and betatron polarization change based on our long-term
equations. This work can be highly valuable for future plasma based high-energy
accelerators and colliders.",2211.00257v1
2023-04-19,Hamiltonian dynamics on the symplectic extended phase space for autonomous and non-autonomous systems,"We will present a consistent description of Hamiltonian dynamics on the
``symplectic extended phase space'' that is analogous to that of a
time-\underline{in}dependent Hamiltonian system on the conventional symplectic
phase space. The extended Hamiltonian $H_{1}$ and the pertaining extended
symplectic structure that establish the proper canonical extension of a
conventional Hamiltonian $H$ will be derived from a generalized formulation of
Hamilton's variational principle. The extended canonical transformation theory
then naturally permits transformations that also map the time scales of
original and destination system, while preserving the extended Hamiltonian
$H_{1}$, and hence the form of the canonical equations derived from $H_{1}$.
The Lorentz transformation, as well as time scaling transformations in
celestial mechanics, will be shown to represent particular canonical
transformations in the symplectic extended phase space. Furthermore, the
generalized canonical transformation approach allows to directly map explicitly
time-dependent Hamiltonians into time-independent ones. An ``extended''
generating function that defines transformations of this kind will be presented
for the time-dependent damped harmonic oscillator and for a general class of
explicitly time-dependent potentials. In the appendix, we will reestablish the
proper form of the extended Hamiltonian $H_{1}$ by means of a Legendre
transformation of the extended Lagrangian $L_{1}$.",2304.09633v1
2023-11-14,Electronic plasma diffusion with radiation reaction force and time-dependent electric field,"In this work the explicit solution of the electronic plasma diffusion with
radiation reaction force, under the action of an exponential decay external
electric field is given. The electron dynamics is described by a classical
generalized Langevin equation characterized by an Ornstein-Uhlenbeck-type
friction memory kernel, with an effective memory time which accounts for the
effective thermal interaction between the electron and its surroundings
(thermal collisions between electrons + radiation reaction force). The incident
electric field exerts an electric force on the electron, which in turn can
induce an additional damping to the braking radiation force, allowing a delay
in the electron characteristic time. This fact allows that the effective memory
time be finite and positive, and as a consequence, obtaining physically
admissible solutions of the stochastic Abraham-Lorentz-like equation. It is
shown that the diffusion process is quasi-Markovian which includes the
radiation effects.",2311.08215v1
2024-02-18,Finite-frequency normal and superfluid drag effects in two-component atomic Bose-Einstein condensates,"Two-component systems consisting of mutually interacting particles can
demonstrate both intracomponent transport effects and intercomponent
entrainment (or drag) effects. In the presence of superfluidity, the
intracomponent transport is characterized by dissipative conductivity and
superfluid weight in the framework of two-fluid model, and intercomponent
entrainment gives rise to normal and nondissipative drag effects. We present
unified treatment of all these effects for spatially homogeneous two-component
atomic Bose-Einstein condensates based on the Bogoliubov theory, focusing
specifically on the drag effects. Calculating finite-frequency intra- and
intercomponent conductivities with taking into account quasiparticle damping,
we derive and numerically check analytical Drude-like approximations applicable
at low frequencies, and Lorentz-like approximations applicable at higher
frequencies in vicinity of the resonant energy of spin-to-density Bogoliubov
quasiparticle conversion. As possible physical realizations of two-component
atomic systems, we consider three-dimensional Bose-Bose mixtures and closely
spaced two-layered systems of magnetic dipolar atoms.",2402.11606v1
2004-09-29,Lorentz violation and neutrinos,"Neutrino oscillations provide an opportunity for sensitive tests of Lorentz
invariance. This talk reviews some aspects of Lorentz violation in neutrinos
and the prospect of testing Lorentz invariance in neutrino-oscillation
experiments. A general Lorentz-violating theory for neutrinos is discussed, and
some signals of Lorentz violation are identified.",0409344v1
2010-09-14,Modeling laser wakefield accelerators in a Lorentz boosted frame,"Modeling of laser-plasma wakefield accelerators in an optimal frame of
reference \cite{VayPRL07} is shown to produce orders of magnitude speed-up of
calculations from first principles. Obtaining these speedups requires
mitigation of a high-frequency instability that otherwise limits effectiveness
in addition to solutions for handling data input and output in a
relativistically boosted frame of reference. The observed high-frequency
instability is mitigated using methods including an electromagnetic solver with
tunable coefficients, its extension to accomodate Perfectly Matched Layers and
Friedman's damping algorithms, as well as an efficient large bandwidth digital
filter. It is shown that choosing the frame of the wake as the frame of
reference allows for higher levels of filtering and damping than is possible in
other frames for the same accuracy. Detailed testing also revealed
serendipitously the existence of a singular time step at which the instability
level is minimized, independently of numerical dispersion, thus indicating that
the observed instability may not be due primarily to Numerical Cerenkov as has
been conjectured. The techniques developed for Cerenkov mitigation prove
nonetheless to be very efficient at controlling the instability. Using these
techniques, agreement at the percentage level is demonstrated between
simulations using different frames of reference, with speedups reaching two
orders of magnitude for a 0.1 GeV class stages. The method then allows direct
and efficient full-scale modeling of deeply depleted laser-plasma stages of 10
GeV-1 TeV for the first time, verifying the scaling of plasma accelerators to
very high energies. Over 4, 5 and 6 orders of magnitude speedup is achieved for
the modeling of 10 GeV, 100 GeV and 1 TeV class stages, respectively.",1009.2727v2
2012-07-24,Doppler Signatures of the Atmospheric Circulation on Hot Jupiters,"The meteorology of hot Jupiters has been characterized primarily with thermal
measurements, but recent observations suggest the possibility of directly
detecting the winds by observing the Doppler shift of spectral lines seen
during transit. Motivated by these observations, we show how Doppler
measurements can place powerful constraints on the meteorology. We show that
the atmospheric circulation--and Doppler signature--of hot Jupiters splits into
two regimes. Under weak stellar insolation, the day-night thermal forcing
generates fast zonal jet streams from the interaction of atmospheric waves with
the mean flow. In this regime, air along the terminator (as seen during
transit) flows toward Earth in some regions and away from Earth in others,
leading to a Doppler signature exhibiting superposed blueshifted and redshifted
components. Under intense stellar insolation, however, the strong thermal
forcing damps these planetary-scale waves, inhibiting their ability to generate
jets. Strong frictional drag likewise damps these waves and inhibits jet
formation. As a result, this second regime exhibits a circulation dominated by
high-altitude, day-to-night airflow, leading to a predominantly blueshifted
Doppler signature during transit. We present state-of-the-art circulation
models including nongray radiative transfer to quantify this regime shift and
the resulting Doppler signatures; these models suggest that cool planets like
GJ 436b lie in the first regime, HD 189733b is transitional, while planets
hotter than HD 209458b lie in the second regime. Moreover, we show how the
amplitude of the Doppler shifts constrains the strength of frictional drag in
the upper atmospheres of hot Jupiters. If due to winds, the ~2-km/sec blueshift
inferred on HD 209458b may require drag time constants as short as 10^4-10^6
seconds, possibly the result of Lorentz-force braking on this planet's hot
dayside.",1207.5639v2
2009-11-04,Conformally flat Lorentz manifolds and Fefferman Lorentz metrics,"We study conformal Fefferman-Lorentz manifolds introduced by Fefferman. To do
so, we introduce Fefferman-Lorentz structure on (2n+2)-dimensional manifolds.
By using causal conformal vector fields preserving that structure, we shall
establish two theorems on compact Fefferman-Lorentz manifolds: One is the
coincidence of vanishing curvature between Weyl conformal curvature tensor of
Fefferman metrics on a Lorentz manifold $S^1\times N$ and Chern-Moser curvature
tensor on a strictly pseudoconvex CR-manifold $N$. Another is the analogue of
the conformal rigidity theorem of Obata and Lelong to the compact
Fefferman-Lorentz manifolds admitting noncompact closed causal conformal
Fefferman-Lorentz transformations.",0911.0867v2
2001-11-27,Constraining Lorentz Violation Using Spectropolarimetry of Cosmological Sources,"Spectropolarimetry of distant sources of electromagnetic radiation at
wavelengths ranging from infrared to ultraviolet are used to constrain Lorentz
violation. A bound of 3x10^{-32} is placed on coefficients for Lorentz
violation.",0111347v1
2001-01-12,The Scaling of the Redshift Power Spectrum: Observations from the Las Campanas Redshift Survey,"In a recent paper we have studied the redshift power spectrum $P^S(k,\mu)$ in
three CDM models with the help of high resolution simulations. Here we apply
the method to the largest available redshift survey, the Las Campanas Redshift
Survey (LCRS). The basic model is to express $P^S(k,\mu)$ as a product of three
factors P^S(k,\mu)=P^R(k)(1+\beta\mu^2)^2 D(k,\mu). Here $\mu$ is the cosine of
the angle between the wave vector and the line of sight. The damping function
$D$ for the range of scales accessible to an accurate analysis of the LCRS is
well approximated by the Lorentz factor D=[1+{1\over
2}(k\mu\sigma_{12})^2]^{-1}. We have investigated different values for $\beta$
($\beta=0.4$, 0.5, 0.6), and measured $P^R(k)$ and $\sigma_{12}(k)$ from
$P^S(k,\mu)$ for different values of $\mu$. The velocity dispersion
$\sigma_{12}(k)$ is nearly a constant from $k=0.5$ to 3 $\mpci$. The average
value for this range is $510\pm 70 \kms$. The power spectrum $P^R(k)$ decreases
with $k$ approximately with $k^{-1.7}$ for $k$ between 0.1 and 4 $\mpci$. The
statistical significance of the results, and the error bars, are found with the
help of mock samples constructed from a large set of high resolution
simulations. A flat, low-density ($\Omega_0=0.2$) CDM model can give a good fit
to the data, if a scale-dependent special bias scheme is used which we have
called the cluster-under-weighted bias (Jing et al.).",0101211v2
2000-11-20,General Formula for the Magnetoresistance on the Basis of the Fermi Liquid Theory,"The general expression for the magnetoresistance (MR) due to the Lorentz
force is derived by using the Fermi liquid transport theory based on the Kubo
formula. The obtained gauge-invariant expression is exact for any strength of
the interaction, as for the most singular term with respect to 1/\gamma^\ast
(\gammak^\ast being the quasiparticle damping rate). By virtue of the
exactness, the conserving laws are satisfied rigorously in the present
expression, which is indispensable for avoiding unphysical solutions. Based on
the derived expression, we can calculate the MR within the framework of the
Baym-Kadanoff type conserving approximation, by including all the vertex
corrections required by the Ward identity. The present expression is
significant especially for strongly correlated systems because the current
vertex corrections will be much important. On the other hand, if we drop all
the vertex corrections in the formula, we get the MR of the relaxation time
approximation (RTA), which is commonly used because of the simplicity. However,
the RTA is dangerous because it may give unphysical results owing to the lack
of conserving laws. In conclusion, the present work enables us to study the MR
with satisfying the conserving laws which is highly demanded in strongly
correlated electrons, such as high-Tc superconductors, organic metals, and
heavy Fermion systems. In Appendix D, we reply to the comment by O. Narikiyo
[cond-mat/0006028]. (Note that Appendix D exists only in the e-preprint
version.)",0011328v3
2009-08-05,Transplanckian bremsstrahlung and black hole production,"Classical gravitational bremsstrahlung in particle collisions at
transplanckian energies is studied in ${\mathcal M}_4\times {\mathcal T}^d$.
The radiation efficiency $\epsilon\equiv E_{\rm rad}/E_{\rm initial}$ is
computed in terms of the Schwarzschild radius $r_S(\sqrt{s})$, the impact
parameter $b$ and the Lorentz factor $\gamma_{\rm cm}$ and found to be
$\epsilon=C_d (r_S/b)^{3d+3} \gamma_{\rm cm}^{2d+1}$, larger than previous
estimates by many powers of $\gamma_{\rm cm}\gg 1$. The result is reliable for
impact parameters in the overlap of $r_S<b<b_c {\rm and} b>\lambda_C$, with
$b_c$ marking (for $d\neq 0$) the loss of the notion of classical trajectories
and $\lambda_C\equiv \hbar/mc$ the Compton length of the scattered particles.
The condition on $s$ and $m$ for extreme radiation damping and (presumably) no
black hole production is also derived.",0908.0675v3
2010-06-09,Scale interactions in magnetohydrodynamic turbulence,"This article reviews recent studies of scale interactions in
magnetohydrodynamic turbulence. The present day increase of computing power,
which allows for the exploration of different configurations of turbulence in
conducting flows, and the development of shell-to-shell transfer functions, has
led to detailed studies of interactions between the velocity and the magnetic
field and between scales. In particular, processes such as induction and dynamo
action, the damping of velocity fluctuations by the Lorentz force, or the
development of anisotropies, can be characterized at different scales. In this
context we consider three different configurations often studied in the
literature: mechanically forced turbulence, freely decaying turbulence, and
turbulence in the presence of a uniform magnetic field. Each configuration is
of interest for different geophysical and astrophysical applications. Local and
non-local transfers are discussed for each case. While the transfer between
scales of solely kinetic or solely magnetic energy is local, transfers between
kinetic and magnetic fields are observed to be local or non-local depending on
the configuration. Scale interactions in the cascade of magnetic helicity are
also reviewed. Based on the results, the validity of several usual assumptions
in hydrodynamic turbulence, such as isotropy of the small scales or
universality, is discussed.",1006.1817v1
2011-09-27,Current-induced forces in mesoscopic systems: a scattering matrix approach,"Nanoelectromechanical systems are characterized by an intimate connection
between electronic and mechanical degrees of freedom. Due to the nanoscopic
scale, current flowing through the system noticeably impacts the vibrational
dynamics of the device, complementing the effect of the vibrational modes on
the electronic dynamics. We employ the scattering matrix approach to quantum
transport to develop a unified theory of nanoelectromechanical systems out of
equilibrium. For a slow mechanical mode, the current can be obtained from the
Landauer-B\""uttiker formula in the strictly adiabatic limit. The leading
correction to the adiabatic limit reduces to Brouwer's formula for the current
of a quantum pump in the absence of the bias voltage. The principal result of
the present paper are scattering matrix expressions for the current-induced
forces acting on the mechanical degrees of freedom. These forces control the
Langevin dynamics of the mechanical modes. Specifically, we derive expressions
for the (typically nonconservative) mean force, for the (possibly negative)
damping force, an effective ""Lorentz"" force which exists even for time reversal
invariant systems, and the fluctuating Langevin force originating from Nyquist
and shot noise of the current flow. We apply our general formalism to several
simple models which illustrate the peculiar nature of the current-induced
forces. Specifically, we find that in out of equilibrium situations the current
induced forces can destabilize the mechanical vibrations and cause limit-cycle
dynamics.",1109.6043v2
2011-10-24,Magnetohydrodynamics dynamical relaxation of coronal magnetic fields. I. Parallel untwisted magnetic fields in 2D,"Context. For the last thirty years, most of the studies on the relaxation of
stressed magnetic fields in the solar environment have onlyconsidered the
Lorentz force, neglecting plasma contributions, and therefore, limiting every
equilibrium to that of a force-free field. Aims. Here we begin a study of the
non-resistive evolution of finite beta plasmas and their relaxation to
magnetohydrostatic states, where magnetic forces are balanced by
plasma-pressure gradients, by using a simple 2D scenario involving a
hydromagnetic disturbance to a uniform magnetic field. The final equilibrium
state is predicted as a function of the initial disturbances, with aims to
demonstrate what happens to the plasma during the relaxation process and to see
what effects it has on the final equilibrium state. Methods. A set of numerical
experiments are run using a full MHD code, with the relaxation driven by
magnetoacoustic waves damped by viscous effects. The numerical results are
compared with analytical calculations made within the linear regime, in which
the whole process must remain adiabatic. Particular attention is paid to the
thermodynamic behaviour of the plasma during the relaxation. Results. The
analytical predictions for the final non force-free equilibrium depend only on
the initial perturbations and the total pressure of the system. It is found
that these predictions hold surprisingly well even for amplitudes of the
perturbation far outside the linear regime. Conclusions. Including the effects
of a finite plasma beta in relaxation experiments leads to significant
differences from the force-free case.",1110.5258v1
2012-10-25,Gravitational bremsstrahlung in ultra-planckian collisions,"A classical computation of gravitational bremsstrahlung in ultra-planckian
collisions of massive point particles is presented in an arbitrary number d of
toroidal or non-compact extra dimensions. Our method generalizes the
post-linear formalism of General Relativity to the multidimensional case. The
total emitted energy, as well as its angular and frequency distribution are
discussed in detail. In terms of the gravitational radius r_S of the collision
energy, the impact parameter b and the Lorentz factor in the CM frame, the
leading order radiation efficiency in the Lab frame is shown to be of order
(r_S/b)^{3(d+1)} gamma_{cm} for d=0, 1 and of order (r_S/b)^{3(d+1)}
gamma_{cm}^{2d-3} for d>1, up to a known d-dependent coefficient and a ln
gamma_{cm} factor for d=2, while the characteristic frequency of the radiation
is gamma/b. The contribution of the low frequency part of the radiation (soft
gravitons) to the total radiated energy is shown to be negligible for all
values of d. The domain of validity of the classical result is discussed.
Finally, it is shown that within the region of validity of our approach the
efficiency can obtain unnatural values greater than one, which is interpreted
to mean that the peripheral ultra-planckian collisions should be strongly
radiation damped.",1210.6976v1
2013-10-09,Dissipation in Relativistic Outflows: A Multisource Overview,"Relativistically expanding sources of X-rays and gamma-rays cover an enormous
range of (central) compactness and Lorentz factor. The underlying physics is
discussed, with an emphasis on how the dominant dissipative mode and the
emergent spectrum depend on these parameters. Photons advected outward from
high optical depth are a potentially important source of Compton seeds. Their
characteristic energy is bounded below by ~1 MeV in pair-loaded outflows of
relatively low compactness, and remains near ~1 MeV at very high compactness
and low matter loading. This is compared with the characteristic energy of O(1)
MeV observed in the rest frame spectra of many sources, including gamma-ray
bursts, OSSE jet sources, MeV Blazars, and the intense initial 0.1 s pulse of
the March 5 event. Additional topics discussed include the feedback of pair
creation on electron heating and the formation of non-thermal spectra, their
effectiveness at shielding the dissipative zone from ambient photons, direct
Compton damping of irregularities in the outflow, the relative importance of
various soft photon sources, and the softening of the emergent spectrum that
results from heavy matter loading. The implications of this work for X-ray and
optical afterglow from GRB's are briefly considered. Direct synchrotron
emission behind the forward shock is inhibited by the extremely low energy
density of the ambient magnetic field. Mildly relativistic ejecta off axis from
the main gamma-ray emitting cone become optically thin to scattering on a
timescale of ~1 day (E/10^{52} erg)^{1/2}, and can be a direct source of
afterglow radiation.",1310.2481v1
2014-09-22,On the Origin of a Sunquake during the 29 March 2014 X1 Flare,"Helioseismic data from the HMI instrument have revealed a sunquake associated
with the X1 flare SOL2014-03-29T17:48 in active region NOAA 12017. We try to
discover if acoustic-like impulses or actions of the Lorentz force caused the
sunquake. We analyze spectro-polarimetric data obtained with the Facility
Infrared Spectrometer (FIRS) at the Dunn Solar Telescope (DST). Fortuitously
the FIRS slit crossed the flare kernel close to the acoustic source, during the
impulsive phase. The infrared FIRS data remain unsaturated throughout the
flare. Stokes profiles of lines of Si I 1082.7 nm and He I 1083.0 nm are
analyzed. At the flare footpoint, the Si I 1082.7 nm core intensity increases
by a factor of several, the IR continuum increases by 4 +/- 1%. Remarkably, the
Si I core resembles the classical Ca II K line's self-reversed profile. With
nLTE radiative models of H, C, Si and Fe these properties set the penetration
depth of flare heating to 100 +/- 100 km, i.e. photospheric layers. Estimates
of the non-magnetic energy flux are at least a factor of two less than the
sunquake energy flux. Milne-Eddington inversions of the Si I line show that the
local magnetic energy changes are also too small to drive the acoustic pulse.
Our work raises several questions: Have we ""missed"" the signature of downward
energy propagation? Is it intermittent in time and/or non-local? Does the 1-2 s
photospheric radiative damping time discount compressive modes?",1409.6268v1
2014-10-28,Equations of a Moving Mirror and the Electromagnetic Field,"We consider a system composed of a mobile slab and the electromagnetic field.
We assume that the slab is made of a material that has the following properties
when it is at rest: it is linear, isotropic, non-magnetizable, and ohmic with
zero free charge density. Using instantaneous Lorentz transformations, we
deduce the set of self-consistent equations governing the dynamics of the
system and we obtain approximate equations to first order in the velocity and
the acceleration of the slab. As a consequence of the motion of the slab, the
field must satisfy a wave equation with damping and slowly varying coefficients
plus terms that are small when the time-scale of the evolution of the mirror is
much smaller than that of the field. Also, the motion of the slab and its
interaction with the field introduce two effects in the slab's equation of
motion. The first one is a position- and time-dependent mass related to the
$\textit{effective mass}$ taken in phenomenological treatments of this type of
systems. The second one is a velocity-dependent force that can give rise to
friction and that is related to the much sought $\textit{cooling}$ of
mechanical objects.",1410.7609v2
2017-08-28,Magnetic reheating,"We provide a new bound on the amplitude of primordial magnetic fields (PMFs)
by using a novel mechanism, named {\it magnetic reheating}. Before the epoch of
recombination, PMFs induce the fluid motions in a photon-baryon plasma through
the Lorentz force. Due to the viscosity in the plasma, such induced fluid
motions would be damped and this means the dissipation of PMFs. In the early
Universe with $z \gtrsim 2 \times 10^6$, cosmic microwave background (CMB)
photons are quickly thermalized with the dissipated energy and shift to a
different Planck distribution with a new temperature. In other words, the
energy injection due to the dissipation of PMFs changes the baryon-photon
number ratio during this era and we name such a process {\it magnetic
reheating}. By using the current results of the baryon-photon number ratio
obtained from the Big Bang nucleosynthesis and CMB observations, we put a
strongest constraint on the amplitude of PMFs on small scales which we can not
access through CMB anisotropy and CMB distortions, $B_{0} \lesssim 1.0 \;
\mu{\rm G}$ at the scales $10^{4} \; h{\rm Mpc}^{-1} < k < 10^{8} \; h{\rm
Mpc}^{-1}$. Moreover, when the spectrum of PMFs is given by the power-law, the
magnetic reheating puts a quite strong constraint in the case of the
blue-tilted spectrum, for example, $B_0 \lesssim 10^{-17} \;{\rm nG}$,
$10^{-23} \;{\rm nG}$, and $10^{-29} \;{\rm nG}$ at 1~comoving Mpc for
$n_{B}=1.0$, $2.0$, and $3.0$, respectively. This constraint would give an
impact on generation mechanisms of PMFs in the early Universe.",1708.08225v2
2010-05-20,Long wavelength unstable modes in the far upstream of relativistic collisionless shocks,"The growth rate of long wavelength kinetic instabilities arising due to the
interaction of a collimated beam of relativistic particles and a cold
unmagnetized plasma are calculated in the ultra relativistic limit. For
sufficiently culminated beams, all long wave-length modes are shown to be
Weibel-unstable, and a simple analytic expression for their growth rate is
derived. For large transverse velocity spreads, these modes become stable. An
analytic condition for stability is given. These analytic results, which
generalize earlier ones given in the literature, are shown to be in agreement
with numerical solutions of the dispersion equation and with the results of
novel PIC simulations in which the electro-magnetic fields are restricted to a
given k-mode. The results may describe the interaction of energetic cosmic
rays, propagating into the far upstream of a relativistic collisionless shock,
with a cold unmagnetized upstream. The long wavelength modes considered may be
efficient in deflecting particles and could be important for diffusive shock
acceleration. It is shown that while these modes grow in relativistic shocks
propagating into electron-positron pair plasmas, they are damped in
relativistic shocks propagating into electron-proton plasmas with moderate
Lorenz factors \Gamma_{sh}\lesssim 100. If these modes dominate the deflection
of energetic cosmic rays in electron-positron shocks, it is argued that
particle acceleration is suppressed at shock frame energies that are larger
than the downstream thermal energy by a factor greater than the shock Lorentz
factor.",1005.3791v1
2012-04-09,Global MRI with Braginskii viscosity in a galactic profile,"We present a global-in-radius linear analysis of the axisymmetric
magnetorotational instability (MRI) in a collisional magnetized plasma with
Braginskii viscosity. For a galactic angular velocity profile $\Omega$ we
obtain analytic solutions for three magnetic field orientations: purely
azimuthal, purely vertical and slightly pitched (almost azimuthal). In the
first two cases the Braginskii viscosity damps otherwise neutrally stable
modes, and reduces the growth rate of the MRI respectively. In the final case
the Braginskii viscosity makes the MRI up to $2\sqrt{2}$ times faster than its
inviscid counterpart, even for \emph{asymptotically small} pitch angles. We
investigate the transition between the Lorentz-force-dominated and the
Braginskii viscosity-dominated regimes in terms of a parameter $\sim \Omega
\nub/B^2$ where $\nub$ is the viscous coefficient and $B$ the Alfv\'en speed.
In the limit where the parameter is small and large respectively we recover the
inviscid MRI and the magnetoviscous instability (MVI). We obtain asymptotic
expressions for the approach to these limits, and find the Braginskii viscosity
can magnify the effects of azimuthal hoop tension (the growth rate becomes
complex) by over an order of magnitude. We discuss the relevance of our results
to the local approximation, galaxies and other magnetized astrophysical
plasmas. Our results should prove useful for benchmarking codes in global
geometries.",1204.1948v1
2016-12-09,High Energy Neutrinos from the Tidal Disruption of Stars,"We study the production of high energy neutrinos in jets from the tidal
disruption of stars by supermassive black holes. The diffuse neutrino flux
expected from these tidal disruption events (TDEs) is calculated both
analytically and numerically, taking account the dependence of the rate of TDEs
on the redshift and black hole mass. We find that ~10% of the observed diffuse
flux at IceCube at an energy of about 1 PeV can come from TDEs if the
characteristics of known jetted tidal disruption events are assumed to apply to
the whole population of these sources. If, however, plausible scalings of the
jet Lorentz factor or variability timescale with the black hole mass are taken
into account, the contribution of the lowest mass black holes to the neutrino
flux is enhanced. In this case, TDEs can account for most of the neutrino flux
detected at IceCube, describing both the neutrino flux normalization and
spectral shape with moderate baryonic loadings. While the uncertainties on our
assumptions are large, a possible signature of TDEs as the origin of the
IceCube signal is the transition of the flux flavor composition from a pion
beam to a muon damped source at the highest energies, which will also result in
a suppression of Glashow resonance events.",1612.03160v2
2018-10-23,Quantum dissipation of planar harmonic systems: Maxwell-Chern-Simons theory,"The conventional Brownian motion in harmonic systems has provided a deep
understanding of a great diversity of dissipative phenomena. We address a
rather fundamental microscopic description for the (linear) dissipative
dynamics of two-dimensional harmonic oscillators that contains the conventional
Brownian motion as a particular instance. This description is derived from
first principles in the framework of the so-called Maxwell-Chern-Simons
electrodynamics, or also known, Abelian topological massive gauge theory.
Disregarding backreaction effects and endowing the system Hamiltonian with a
suitable renormalized potential interaction, the conceived description is
equivalent to a minimal-coupling theory with a gauge field giving rise to a
fluctuating force that mimics the Lorentz force induced by a particle-attached
magnetic flux. We show that the underlying symmetry structure of the theory
(i.e. time-reverse asymmetry and parity violation) yields an interacting
vortex-like Brownian dynamics for the system particles. An explicit comparison
to the conventional Brownian motion in the quantum Markovian limit reveals that
the proposed description represents a second-order correction to the well-known
damped harmonic oscillator, which manifests that there may be dissipative
phenomena intrinsic to the dimensionality of the interesting system.",1810.09857v3
2020-02-27,Dipole polarizability of time-varying particles,"Invariance under time translation (or stationarity) is probably one of the
most important assumptions made when investigating electromagnetic phenomena.
Breaking this assumption is expected to open up novel possibilities and result
in exceeding conventional limitations. However, to explore the field of
time-varying electromagnetic structures, we primarily need to contemplate the
fundamental principles and concepts from a nonstationarity perspective. Here,
we revisit one of those key concepts: The polarizability of a small particle,
assuming that its properties vary in time. We describe the creation of induced
dipole moment by external fields in a nonstationary, causal way, and introduce
a complex-valued function, called temporal complex polarizability, for
elucidating a nonstationary Hertzian dipole under time-harmonic illumination.
This approach can be extended to any subwavelength particle exhibiting electric
response. In addition, we also study the classical model of the polarizability
of an oscillating electron using the equation of motion whose damping
coefficient and natural frequency are changing in time. Next, we theoretically
derive the effective permittivity corresponding to time-varying media
(comprising free or bound electrons, or dipolar meta-atoms) and explicitly show
the differences with the conventional macroscopic Drude-Lorentz model. This
paper will hopefully pave the road towards better understanding of
nonstationary scattering from small particles and homogenization of
time-varying materials, metamaterials, and metasurfaces.",2002.12297v3
2018-03-26,Radiation reaction of charged particles orbiting magnetized Schwarzschild black hole,"In many astrophysically relevant situations radiation reaction force acting
upon a charge can not be neglected and the question arises about the location
and stability of circular orbits in such regime. Motion of point charge with
radiation reaction in flat spacetime is described by Lorenz-Dirac (LD)
equation, while in curved spacetime -- by DeWitt-Brehme (DWB) equation
containing the Ricci term and the tail term. We show that for the motion of
elementary particles in vacuum metrics the DWB equation can be reduced to the
covariant form of the LD equation which we use here. Generically, the LD
equation is plagued by runaway solutions, so we discuss computational ways to
avoid this problem in constructing numerical solutions. We also use the first
iteration of the covariant LD equation which is the covariant Landau-Lifshitz
equation, comparing results of these two approaches and showing smallness of
the third-order Schott term in the ultrarelativistic case. We calculate the
corresponding energy and angular momentum loss of a particle and study the
damping of charged particle oscillations around an equilibrium radius. We find
that depending on the orientation of the Lorentz force, the oscillating charged
particle either spirals down to the black hole, or stabilizes the circular
orbit by decaying its oscillations. The later case leads to an interesting new
result of shifting of the particle orbit outwards from the black hole. We also
discuss the astrophysical relevance of the presented approach and provide
estimations of the main parameters of the model.",1803.09682v1
2020-10-27,Legolas: a modern tool for magnetohydrodynamic spectroscopy,"Magnetohydrodynamic (MHD) spectroscopy is central to many astrophysical
disciplines, ranging from helio- to asteroseismology, over solar coronal (loop)
seismology, to the study of waves and instabilities in jets, accretion disks,
or solar/stellar atmospheres. MHD spectroscopy quantifies all linear (standing
or travelling) wave modes, including overstable (i.e. growing) or damped modes,
for a given configuration that achieves force and thermodynamic balance. Here,
we present Legolas, a novel, open-source numerical code to calculate the full
MHD spectrum of one-dimensional equilibria with flow, that balance pressure
gradients, Lorentz forces, centrifugal effects and gravity, enriched with
non-adiabatic aspects like radiative losses, thermal conduction and
resistivity. The governing equations use Fourier representations in the
ignorable coordinates, and the set of linearised equations are discretised
using Finite Elements in the important height or radial variation, handling
Cartesian and cylindrical geometries using the same implementation. A weak
Galerkin formulation results in a generalised (non-Hermitian) matrix eigenvalue
problem, and linear algebraic algorithms calculate all eigenvalues and
corresponding eigenvectors. We showcase a plethora of well-established results,
ranging from p- and g-modes in magnetised, stratified atmospheres, over modes
relevant for coronal loop seismology, thermal instabilities and discrete
overstable Alfv\'en modes related to solar prominences, to stability studies
for astrophysical jet flows. We encounter (quasi-)Parker, (quasi-)interchange,
current-driven and Kelvin-Helmholtz instabilities, as well as non-ideal
quasi-modes, resistive tearing modes, up to magneto-thermal instabilities. The
use of high resolution sheds new light on previously calculated spectra,
revealing interesting spectral regions that have yet to be investigated.",2010.14148v2
2021-08-16,Drifting Electrons: Nonreciprocal Plasmonics and Thermal Photonics,"Light propagates symmetrically in opposite directions in most materials and
structures. This fact -- a consequence of the Lorentz reciprocity principle --
has tremendous implications for science and technology across the
electromagnetic spectrum. Here, we investigate an emerging approach to break
reciprocity that does not rely on magneto-optical effects or spacetime
modulations, but is instead based on biasing a plasmonic material with a direct
electric current. Using a 3D Green function formalism and microscopic
considerations, we elucidate the propagation properties of surface
plasmon-polaritons (SPPs) supported by a generic nonreciprocal platform of this
type, revealing some previously overlooked, anomalous, wave-propagation
effects. We show that SPPs can propagate in the form of steerable, slow-light,
unidirectional beams associated with inflexion points in the modal dispersion.
We also clarify the impact of dissipation (due to collisions and Landau
damping) on nonreciprocal effects and shed light on the connections between
inflexion points, exceptional points at band-edges, and complex modal
transitions in leaky-wave structures. We then apply these concepts to the
important area of thermal photonics, and provide the first theoretical
demonstration of drift-induced nonreciprocal near-field radiative heat transfer
between two planar bodies. Our findings may open new opportunities toward the
development of nonreciprocal magnet-free devices that combine the benefits of
plasmonics and nonreciprocal photonics for wave-guiding and energy
applications.",2108.07246v2
2021-11-03,Interplay of interactions and disorder at the charge-density wave transition of two-dimensional Dirac semimetals,"We consider the effects of weak quenched fermionic disorder on the
quantum-phase transition between the Dirac semimetal and charge density wave
(CDW) insulator in two spatial dimensions. The symmetry breaking transition is
described by the Gross-Neveu-Yukawa (GNY) theory of Dirac fermions coupled to
an Ising order parameter field. Treating the disorder using the replica method,
we consider chemical potential, vector potential (gauge), and random mass
disorders, which all arise from non-magnetic charge impurities. We
self-consistently account for the Landau damping of long-wavelength
order-parameter fluctuations by using the non-perturbative RPA re-summation of
fermion loops, and compute the renormalization-group (RG) flow to leading order
in the disorder strength and $1/N$ ($N$ the number of Dirac fermion flavors).
We find two fixed points, the clean GNY critical point which is stable against
weak disorder, and a dirty GNY multi-critical point, at which the chemical
potential disorder is finite and the other forms of disorder are irrelevant. We
investigate the scaling of physical observables at this finite-disorder
multi-critical point which breaks Lorentz invariance and gives rise to distinct
non-Fermi liquid behavior.",2111.02502v2
2022-11-09,Gravitational wave constraints on spatial covariant gravities,"The direct discovery of gravitational waves (GWs) from the coalescence of
compact binary components by the LIGO/Virgo/KAGRA Collaboration provides an
unprecedented opportunity for exploring the underlying theory of gravity that
drives the coalescence process in the strong and highly dynamical field regime
of gravity. In this paper, we consider the observational effects of spatial
covariant gravities on the propagation of GWs in the cosmological background
and obtain the observational constraints on coupling coefficients in the action
of spatial covariant gravities from GW observations. We first decompose the GWs
into the left- and right-hand circular polarization modes and derive the
effects of the spatial covariant gravities on the propagation equation of GWs.
We find that these effects can be divided into three classes: 1)
frequency-independent effects on GW speed and friction, 2) parity-violating
amplitude and velocity birefringences, and 3) a Lorentz-violating damping rate
and dispersion of GWs. With these effects, we calculate the corresponding
modified waveform of GWs generated by the coalescence of compact binaries. By
comparing these new effects with the publicly available posterior samples or
results from various tests of gravities with LIGO/Virgo/KAGRA data in the
literature, we derive the observational constraints on coupling coefficients of
the spatial covariant gravities. These results represent the most comprehensive
constraints on the spatial covariant gravities in the literature.",2211.04711v2
2023-07-14,A new radiation reaction approximation for particle dynamics in the strong field regime,"(Abridged) Following particle trajectories in the intense electromagnetic
field of a neutron star is prohibited by the large ratio between the cyclotron
frequency $\omega_{\rm B}$ and the stellar rotation frequency $\Omega$. No
fully kinetic simulations on a macroscopic scale and with realistic field
strengths have been performed so far due to the huge computational cost implied
by this enormous scale of separation. In this paper, we derive new expressions
for the particle velocity subject to strong radiation reaction that are
intended to be more accurate than the current state-of-the-art expression in
the radiation reaction limit regime, the so-called Aristotelian regime. We
shortened the timescale hierarchy by solving the particle equation of motion in
the radiation reaction regime, where the Lorentz force is always and
immediately balanced by the radiative drag, and including a friction not
necessarily opposite to the velocity vector, as derived in the Landau-Lifshitz
approximation. Starting from the reduced Landau-Lifshitz equation (i.e.
neglecting the field time derivatives), we found expressions for the velocity
depending only on the local electromagnetic field configuration and on a new
parameter related to the field strength that controls the strength of the
radiative damping. The new velocity expressions produce results similar in
accuracy to the radiation reaction limit approximation. We therefore do not
expect this new method to improve the accuracy of neutron star magnetosphere
simulations. The radiation reaction limit is a simple but accurate, robust, and
efficient way to follow ultra-relativistic particles in a strong
electromagnetic field.",2307.07591v2
2024-02-13,Hyperballistic transport in dense ionized matter under external AC electric fields,"The Langevin equation is ubiquitously employed to numerically simulate
plasmas and dusty plasmas. However, the usual assumption of white noise becomes
untenable when the system is subject to an external AC electric field. This is
because the charged particles in the plasma, which provide the thermal bath for
the particle transport, become themselves responsive to the AC field and the
thermal noise is field-dependent and non-Markovian. We theoretically study the
particle diffusivity in a Langevin transport model for a tagged charged
particle immersed in a dense plasma of charged particles that act as the
thermal bath, under an external AC electric field, by properly accounting for
the effects of the AC field on the thermal bath statistics. We analytically
derive the time-dependent generalized diffusivity $D(t)$ for different initial
conditions. The generalized diffusivity exhibits damped oscillatory-like
behaviour with initial very large peaks, where the generalized diffusion
coefficient is enhanced by orders of magnitude with respect to the
infinite-time steady-state value. The latter coincides with the Stokes-Einstein
diffusivity in the absence of external field. For initial conditions where the
external field is already on at $t=0$ and the system is thermalized under DC
conditions for $t \leq 0$, the short-time behaviour is hyperballistic, $MSD
\sim t^4$ (where MSD is the mean-squared displacement), leading to giant
enhancement of the particle transport. Finally, the theory elucidates the role
of medium polarization on the local Lorentz field, and allows for estimates of
the effective electric charge due to polarization by the surrounding charges.",2402.08519v2
2006-02-22,"A faster than ""World fastest derivation of the Lorentz transformation""","We show that a derivation of the Lorentz-Einstein transformation based on
length contraction or on time dilation is faster then ""World's fastest
derivation of the Lorentz transformation""",0602153v1
2009-08-12,Linear Fractionally Damped Oscillator,"In this paper the linearly damped oscillator equation is considered with the
damping term generalized to a Caputo fractional derivative. The order of the
derivative being considered is 0 less than or equal to nu which is less than or
equal to 1 . At the lower end, nu = 0, the equation represents an un-damped
oscillator and at the upper end, nu = 1, the ordinary linearly damped
oscillator equation is recovered. A solution is found analytically and a
comparison with the ordinary linearly damped oscillator is made. It is found
that there are nine distinct cases as opposed to the usual three for the
ordinary equation (damped, over-damped, and critically damped). For three of
these cases it is shown that the frequency of oscillation actually increases
with increasing damping order before eventually falling to the limiting value
given by the ordinary damped oscillator equation. For the other six cases the
behavior is as expected, the frequency of oscillation decreases with increasing
order of the derivative (damping term).",0908.1683v1
2005-11-10,Lorentz-Violating Electromagnetostatics,"In this talk, the stationary limit of Lorentz-violating electrodynamics is
discussed. As illustrated by some simple examples, the general solution
includes unconventional mixing of electrostatic and magnetostatic effects. I
discuss a high-sensitivity null-type measurement, exploiting Lorentz-violating
electromagnetostatic effects, that could improve existing limits on parity-odd
coefficients for Lorentz violation in the photon sector.",0511122v1
2010-09-23,Lorentz violation in solar-neutrino oscillations,"Solar-neutrino oscillations are considered using a massive model with
perturbative Lorentz violation. The adiabatic approximation is used to
calculate the effects of Lorentz violation to leading order. The results are
more compact than previous work involving vacuum oscillations, and are accurate
for small Lorentz-violating coefficients.",1009.4717v1
2016-10-28,Lorentz-Violating QCD Corrections to Deep Inelastic Scattering,"In this work, we present CPT- and Lorentz-violating corrections to observable
quantities in electron-proton scattering. We also show how the theoretical
prediction can be used together with data to establish bounds on a coefficient
for CPT and Lorentz violation in the QCD sector.",1610.09430v1
2012-01-29,The exponential of the spin representation of the Lorentz algebra,"As discussed in a previous article, any (real) Lorentz algebra element
possess a unique orthogonal decomposition as a sum of two mutually annihilating
decomposable Lorentz algebra elements. In this article, this concept is
extended to the spin representation of the Lorentz algebra. As an application,
a formula for the exponential of the spin representation is obtained, as well
as a formula for the spin representation of a proper orthochronous Lorentz
transformation.",1201.6047v1
2022-12-28,Atomic decomposition for Morrey-Lorentz spaces,"In this paper, we consider the atomic decomposition for Morrey-Lorentz spaces
and applications. Morrey-Lorentz spaces, which have structures of Morrey
spaces, Lorentz spaces and their weak-type spaces, are introduced by M. A.
Ragusa in 2012. Our study gave some extension of the atomic decomposition to
Morrey-Lorentz spaces. As an application, the Olsen inequality can be obtained
more sharpness.",2212.13717v1
1998-02-23,Shell Effects on Rotational Damping in Superdeformed Nuclei,"Damping of rotational motion in superdeformed Hg and Dy-region nuclei is
studied by means of cranked shell model diagonalization. It is shown that a
shell oscillation in single-particle alignments affects significantly
properties of rotational damping. Onset properties of damping and damping width
for Hg are quite different from those for Dy-region superdeformed nuclei.",9802065v1
2003-08-29,Influence of radiative damping on the optical-frequency susceptibility,"Motivated by recent discussions concerning the manner in which damping
appears in the electric polarizability, we show that (a) there is a dependence
of the nonresonant contribution on the damping and that (b) the damping enters
according to the ""opposite sign prescription."" We also discuss the related
question of how the damping rates in the polarizability are related to
energy-level decay rates.",0309001v1
2024-03-19,Weakly elliptic damping gives sharp decay,"We prove that weakly elliptic damping gives sharp energy decay for the
abstract damped wave semigroup, where the damping is not in the functional
calculus. In this case, there is no overdamping. We show applications in
linearised water waves and Kelvin--Voigt damping.",2403.13067v1
1991-01-02,Comparison of Orlicz-Lorentz spaces,"Orlicz-Lorentz spaces provide a common generalization of Orlicz spaces and
Lorentz spaces. They have been studied by many authors, including Masty\l o,
Maligranda, and Kami\'nska. In this paper, we consider the problem of comparing
the Orlicz-Lorentz norms, and establish necessary and sufficient conditions for
them to be equivalent. As a corollary, we give necessary and sufficient
conditions for a Lorentz-Sharpley space to be equivalent to an Orlicz space,
extending results of Lorentz and Raynaud. We also give an example of a
rearrangement invariant space that is not an Orlicz-Lorentz space.",9201221v2
2008-05-08,The Lorentz group and its finite field analogues: local isomorphism and approximation,"Finite Lorentz groups acting on 4-dimensional vector spaces coordinatized by
finite fields with a prime number of elements are represented as homomorphic
images of countable, rational subgroups of the Lorentz group acting on real
4-dimensional space-time. Bounded subsets of the real Lorentz group are
retractable with arbitrary accuracy to finite subsets of such rational
subgroups. These finite retracts correspond, via local isomorphisms, to
well-behaved subsets of Lorentz groups over finite fields. This establishes a
relationship of approximation between the real Lorentz group and Lorentz groups
over very large finite fields.",0805.1224v2
2021-06-21,Gagliardo-Nirenberg inequalities in Lorentz type spaces and energy equality for the Navier-Stokes system,"In this paper, we derive some new Gagliardo-Nirenberg type inequalities in
Lorentz type spaces without restrictions on the second index of Lorentz norms,
which generalize almost all known corresponding results. Our proof mainly
relies on the Bernstein inequalities in Lorentz spaces, the embedding relation
among various Lorentz type spaces, and Littlewood-Paley decomposition
techniques. In addition, we establish several novel criteria in terms of the
velocity or the gradient of the velocity in Lorentz spaces for energy
conservation of the 3D Navier-Stokes equations. Particularly, we improve the
classical Shinbrot's condition for energy balance to allow both the space-time
directions of the velocity to be in Lorentz spaces.",2106.11212v1
2015-05-15,Reliable Damping of Free Surface Waves in Numerical Simulations,"This paper generalizes existing approaches for free-surface wave damping via
momentum sinks for flow simulations based on the Navier-Stokes equations. It is
shown in 2D flow simulations that, to obtain reliable wave damping, the
coefficients in the damping functions must be adjusted to the wave parameters.
A scaling law for selecting these damping coefficients is presented, which
enables similarity of the damping in model- and full-scale. The influence of
the thickness of the damping layer, the wave steepness, the mesh fineness and
the choice of the damping coefficients are examined. An efficient approach for
estimating the optimal damping setup is presented. Results of 3D ship
resistance computations show that the scaling laws apply to such simulations as
well, so the damping coefficients should be adjusted for every simulation to
ensure convergence of the solution in both model and full scale. Finally,
practical recommendations for the setup of reliable damping in flow simulations
with regular and irregular free surface waves are given.",1505.04087v2
2019-02-25,Resonant absorption as a damping mechanism for the transverse oscillations of the coronal loops observed by SDO/AIA,"Solar coronal loops represent the variety of fast, intermediate, and slow
normal mode oscillations. In this study, the transverse oscillations of the
loops with a few-minutes period and also with damping caused by the resonant
absorption were analyzed using extreme ultraviolet (EUV) images of the Sun. We
employed the 171 $\AA$ data recorded by Solar Dynamic Observatory
(SDO)/Atmospheric Imaging Assembly (AIA) to analyze the parameters of coronal
loop oscillations such as period, damping time, loop length, and loop width.
For the loop observed on 11 October 2013, the period and the damping of this
loop are obtained to be 19 and 70 minutes, respectively. The damping quality,
the ratio of the damping time to the period, is computed about 3.6. The period
and damping time for the extracted loop recorded on 22 January 2013 are about
81 and 6.79 minutes, respectively. The damping quality is also computed as 12.
It can be concluded that the damping of the transverse oscillations of the
loops is in the strong damping regime, so resonant absorption would be the main
reason for the damping.",1902.09649v1
2013-05-21,Characterization and Synthesis of Rayleigh Damped Elastodynamic Networks,"We consider damped elastodynamic networks where the damping matrix is assumed
to be a non-negative linear combination of the stiffness and mass matrices
(also known as Rayleigh or proportional damping). We give here a
characterization of the frequency response of such networks. We also answer the
synthesis question for such networks, i.e., how to construct a Rayleigh damped
elastodynamic network with a given frequency response. Our analysis shows that
not all damped elastodynamic networks can be realized when the proportionality
constants between the damping matrix and the mass and stiffness matrices are
fixed.",1305.4961v1
2016-08-08,Damping Functions correct over-dissipation of the Smagorinsky Model,"This paper studies the time-averaged energy dissipation rate $\langle
\varepsilon_{SMD} (u)\rangle$ for the combination of the Smagorinsky model and
damping function. The Smagorinsky model is well known to over-damp. One common
correction is to include damping functions that reduce the effects of model
viscosity near walls. Mathematical analysis is given here that allows
evaluation of $\langle \varepsilon_{SMD} (u)\rangle $ for any damping function.
Moreover, the analysis motivates a modified van Driest damping. It is proven
that the combination of the Smagorinsky with this modified damping function
does not over dissipate and is also consistent with Kolmogorov phenomenology.",1608.02655v2
2003-07-06,Localization of Lorentz transformation and its induced local Lorentz invariance,"Introducing the primed inertial coordinate system, for each inertial frame of
reference, in addition to the usual inertial coordinate system, we assume that
gravity-free space and time possess the Euclidean structures in the primed
inertial coordinate system and the generalized Finslerian structures in the
usual inertial coordinate system. We combine these assumptions with two
fundamental postulates, (i) the principle of relativity and (ii) the constancy
of the speed of light in all inertial frames of reference, to derive the
localized Lorentz transformation as a linear transformation between any two
usual inertial coordinate systems. Based on this, it is proposed that all laws
of physics are locally Lorentz-invariant in the usual inertial coordinate
system. As a Lorentz-invariant law of physics must be locally Lorentz-invariant
while a locally Lorentz-invariant law is not necessarily Lorentz-invariant, the
change from the requirement of Lorentz invariance to that of the local Lorentz
invariance on laws of physics provides with a larger acceptable scope to
explore these laws.",0307041v1
2020-08-02,Integration of Dirac's Efforts to construct Lorentz-covariant Quantum Mechanics,"The lifelong efforts of Paul A. M. Dirac were to construct localized quantum
systems in the Lorentz covariant world. In 1927, he noted that the time-energy
uncertainty should be included in the Lorentz-covariant picture. In 1945, he
attempted to construct a representation of the Lorentz group using a
normalizable Gaussian function localized both in the space and time variables.
In 1949, he introduced his instant form to exclude time-like oscillations. He
also introduced the light-cone coordinate system for Lorentz boosts. Also in
1949, he stated the Lie algebra of the inhomogeneous Lorentz group can serve as
the uncertainty relations in the Lorentz-covariant world. It is possible to
integrate these three papers to produce the harmonic oscillator wave function
which can be Lorentz-transformed. In addition, Dirac, in 1963, considered two
coupled oscillators to derive the Lie algebra for the generators of the
$O(3,\,2)$ de Sitter group, which has ten generators. It is proven possible to
contract this group to the inhomogeneous Lorentz group with ten generators,
which constitute the fundamental symmetry of quantum mechanics in Einstein's
Lorentz-covariant world.",2008.00551v1
2012-11-30,Tests of Lorentz and CPT violation with neutrinos,"Lorentz violation is a predicted phenomenon from the Planck scale physics.
Although the three active massive neutrino framework with the Standard Model
(SM), so-called the neutrino Standard Model (nuSM), is successful, series of
signals not understood within the nuSM suggest neutrino physics may be the
first place to see the physics beyond the SM, such as Lorentz violation.
Especially, neutrino oscillations are the natural interferometer and they are
sensitive to the Lorentz violation.
  The LSND oscillation signal was analyzed under the Standard Model Extension
(SME) framework, and it was found that the oscillation data was consistent with
no Lorentz violation, but data cannot reject Lorentz violation hypothesis with
order ~10^{-17}. By assuming LSND signal was due to the Lorentz violation, a
global phenomenological model was made to describe all known oscillation data
including the LSND signal. The model also predicted the signal for MiniBooNE at
the low energy region.
  Later, MiniBooNE announced an event excess at the low energy region. However,
the oscillation candidate signals from MiniBooNE were consistent with no
Lorentz violation. The limit obtained by MiniBooNE and MINOS on the e-mu sector
reject the simple scenario to explain LSND signal with Lorentz violation.
  Meantime, MINOS and IceCube set tight limits on the mu-tau sector Lorentz
violation. The last untested channel, the e-tau Lorentz violating mixing, was
tested using reactor disappearance data from Double Chooz. However, Double
Chooz data was consistent with flat, and sidereal time dependent Lorentz
violation hypothesis is rejected. Combinations of all oscillation data from
LSND, MiniBooNE, MINOS, IceCube, and Double Chooz provide very tight constraint
for a possible Lorentz violation in the neutrino sector in terrestrial level.",1211.7129v1
2000-09-11,Numerical Studies on Locally Damped Structures,"In the JLC/NLC X-band linear collider, it is essential to reduce the
long-range dipole wakefields in the accelerator structure to prevent beam break
up (BBU) and emittance degradation. The two methods of reducing the long-range
wakefields are detuning and damping. Detuning reduces the wakefields rapidly as
the dipole modes de-cohere but, with a finite number of modes, the wakefield
will grow again as the modes re-cohere. In contrast, damping suppresses the
wakefields at a longer distance. There are two principal damping schemes:
synchronous damping using HOM manifolds such as that used in the RDDS1
structure and local damping similar to that used in the CLIC structure. In a
locally damped scheme, one can obtain almost any Q value, however, the damping
can have significant effects on the accelerating mode. In this paper, we
present a medium local-damping scheme where the wakefields are controlled to
meet the BBU requirement while minimizing the degradations of the fundamental
rf parameters. We will address the load design and pulse heating issues
associated with the medium damping scheme.",0009039v1
2015-03-13,A one-step optimal energy decay formula for indirectly nonlinearly damped hyperbolic systems coupled by velocities,"In this paper, we consider the energy decay of a damped hyperbolic system of
wave-wave type which is coupled through the velocities. We are interested in
the asymptotic properties of the solutions of this system in the case of
indirect nonlinear damping, i.e. when only one equation is directly damped by a
nonlinear damping. We prove that the total energy of the whole system decays as
fast as the damped single equation. Moreover, we give a one-step general
explicit decay formula for arbitrary nonlinearity. Our results shows that the
damping properties are fully transferred from the damped equation to the
undamped one by the coupling in velocities, different from the case of
couplings through displacements as shown in \cite{AB01, ACK01, AB02, AL12} for
the linear damping case, and in \cite{AB07} for the nonlinear damping case. The
proofs of our results are based on multiplier techniques, weighted nonlinear
integral inequalities and the optimal-weight convexity method of \cite{AB05,
AB10}.",1503.04126v1
2015-08-21,Radiative damping in wave guide based FMR measured via analysis of perpendicular standing spin waves in sputtered Permalloy films,"The damping $\alpha$ of the spinwave resonances in 75 nm, 120 nm, and 200nm
-thick Permalloy films is measured via vector-network-analyzer
ferromagnetic-resonance (VNA-FMR) in the out-of-plane geometry. Inductive
coupling between the sample and the waveguide leads to an additional radiative
damping term. The radiative contribution to the over-all damping is determined
by measuring perpendicular standing spin waves (PSSWs) in the Permalloy films,
and the results are compared to a simple analytical model. The damping of the
PSSWs can be fully explained by three contributions to the damping: The
intrinsic damping, the eddy-current damping, and the radiative damping. No
other contributions were observed. Furthermore, a method to determine the
radiative damping in FMR measurements with a single resonance is suggested.",1508.05265v1
2016-02-23,Experimental Investigation of Temperature-Dependent Gilbert Damping in Permalloy Thin Films,"The Gilbert damping of ferromagnetic materials is arguably the most important
but least understood phenomenological parameter that dictates real-time
magnetization dynamics. Understanding the physical origin of the Gilbert
damping is highly relevant to developing future fast switching spintronics
devices such as magnetic sensors and magnetic random access memory. Here, we
report an experimental study of temperature-dependent Gilbert damping in
permalloy (Py) thin films of varying thicknesses by ferromagnetic resonance.
From the thickness dependence, two independent contributions to the Gilbert
damping are identified, namely bulk damping and surface damping. Of particular
interest, bulk damping decreases monotonically as the temperature decreases,
while surface damping shows an enhancement peak at the temperature of ~50 K.
These results provide an important insight to the physical origin of the
Gilbert damping in ultrathin magnetic films.",1602.07325v1
2017-09-29,Non-local Gilbert damping tensor within the torque-torque correlation model,"An essential property of magnetic devices is the relaxation rate in magnetic
switching which depends strongly on the damping in the magnetisation dynamics.
It was recently measured that damping depends on the magnetic texture and,
consequently, is a non-local quantity. The damping enters the
Landau-Lifshitz-Gilbert equation as the phenomenological Gilbert damping
parameter $\alpha$, that does not, in a straight forward formulation, account
for non-locality. Efforts were spent recently to obtain Gilbert damping from
first principles for magnons of wave vector $\mathbf{q}$. However, to the best
of our knowledge, there is no report about real space non-local Gilbert damping
$\alpha_{ij}$. Here, a torque-torque correlation model based on a tight binding
approach is applied to the bulk elemental itinerant magnets and it predicts
significant off-site Gilbert damping contributions, that could be also
negative. Supported by atomistic magnetisation dynamics simulations we reveal
the importance of the non-local Gilbert damping in atomistic magnetisation
dynamics. This study gives a deeper understanding of the dynamics of the
magnetic moments and dissipation processes in real magnetic materials. Ways of
manipulating non-local damping are explored, either by temperature, material's
doping or strain.",1709.10365v1
2022-09-28,Tunable nonlinear damping in parametric regime,"Nonlinear damping plays a significant role in several area of physics and it
is becoming increasingly important to understand its underlying mechanism.
However, microscopic origin of nonlinear damping is still a debatable topic.
Here, we probe and report nonlinear damping in a highly tunable MoS2 nano
mechanical drum resonator using electrical homodyne actuation and detection
technique. In our experiment, we achieve 2:1 internal resonance by tuning
resonance frequency and observe enhanced non-linear damping. We probe the
effect of non-linear damping by characterizing parametric gain. Geometry and
tunability of the device allow us to reduce the effect of other prominent
Duffing non-linearity to probe the non-linear damping effectively. The enhanced
non-linear damping in the vicinity of internal resonance is also observed in
direct drive, supporting possible origin of non-linear damping. Our experiment
demonstrates, a highly tunable 2D material based nanoresonator offers an
excellent platform to study the nonlinear physics and exploit nonlinear damping
in parametric regime.",2209.14120v1
2005-11-07,The Effects of Alfven Waves and Radiation Pressure in Dusty Winds of Late-Type Stars. II. Dust-Cyclotron Damping,"There are in the literature several theories to explain the mass loss in
stellar winds. In particular, for late-type stars, some authors have proposed a
wind model driven by an outward-directed flux of damped Alfven waves. The winds
of these stars present great amounts of dust particles that, if charged, can
give rise to new wave modes or modify the pre-existing ones. In this work, we
study how the dust can affect the propagation of Alfven waves in these winds
taking into account a specific damping mechanism, dust-cyclotron damping. This
damping affects the Alfven wave propagation near the dust-cyclotron frequency.
Hence, if we assume a dust size distribution, the damping occurs over a broad
band of wave frequencies. In this work, we present a model of Alfven
wave-driven winds using the dust-cyclotron damping mechanism. On the basis of
coronal holes in the Sun, which present a superradial expansion, our model also
assumes a diverging geometry for the magnetic field. Thus, the mass, momentum,
and energy equations are obtained and then solved in a self-consistent
approach. Our results of wind velocity and temperature profiles for a typical
K5 supergiant star shows compatibility with observations. We also show that,
considering the presence of charged dust particles, the wave flux is less
damped due to the dust-cyclotron damping than it would be if we consider some
other damping mechanisms studied in the literature, such as nonlinear damping,
resonant surface damping, and turbulent damping.",0511192v2
2013-09-11,Initial versus tangent stiffness-based Rayleigh damping in inelastic time history seismic analyses,"In the inelastic time history analyses of structures in seismic motion, part
of the seismic energy that is imparted to the structure is absorbed by the
inelastic structural model, and Rayleigh damping is commonly used in practice
as an additional energy dissipation source. It has been acknowledged that
Rayleigh damping models lack physical consistency and that, in turn, it must be
carefully used to avoid encountering unintended consequences as the appearance
of artificial damping. There are concerns raised by the mass proportional part
of Rayleigh damping, but they are not considered in this paper. As far as the
stiffness proportional part of Rayleigh damping is concerned, either the
initial structural stiffness or the updated tangent stiffness can be used. The
objective of this paper is to provide a comprehensive comparison of these two
types of Rayleigh damping models so that a practitioner (i) can objectively
choose the type of Rayleigh damping model that best fits her/his needs and (ii)
is provided with useful analytical tools to design Rayleigh damping model with
good control on the damping ratios throughout inelastic analysis. To that end,
a review of the literature dedicated to Rayleigh damping within these last two
decades is first presented; then, practical tools to control the modal damping
ratios throughout the time history analysis are developed; a simple example is
finally used to illustrate the differences resulting from the use of either
initial or tangent stiffness-based Rayleigh damping model.",1309.2741v1
2017-07-14,Damping of gravitational waves by matter,"We develop a unified description, via the Boltzmann equation, of damping of
gravitational waves by matter, incorporating collisions. We identify two
physically distinct damping mechanisms -- collisional and Landau damping. We
first consider damping in flat spacetime, and then generalize the results to
allow for cosmological expansion. In the first regime, maximal collisional
damping of a gravitational wave, independent of the details of the collisions
in the matter is, as we show, significant only when its wavelength is
comparable to the size of the horizon. Thus damping by intergalactic or
interstellar matter for all but primordial gravitational radiation can be
neglected. Although collisions in matter lead to a shear viscosity, they also
act to erase anisotropic stresses, thus suppressing the damping of
gravitational waves. Damping of primordial gravitational waves remains
possible. We generalize Weinberg's calculation of gravitational wave damping,
now including collisions and particles of finite mass, and interpret the
collisionless limit in terms of Landau damping. While Landau damping of
gravitational waves cannot occur in flat spacetime, the expansion of the
universe allows such damping by spreading the frequency of a gravitational wave
of given wavevector.",1707.05192v2
1997-11-26,Isometry groups and geodesic foliations of Lorentz manifolds. Part II: Geometry of analytic Lorentz manifolds with large isometry groups,"This is Part II of a series on noncompact isometry groups of
  Lorentz manifolds. We have introduced in Part I, a compactification of these
isometry groups, and called ``bi-polarized'' those Lorentz manifolds having a
``trivial '' compactification. Here we show a geometric rigidity of
non-bi-polarized Lorentz manifolds; that is, they are (at least locally) warped
products of constant curvature Lorentz manifolds by Riemannian manifolds.",9711020v1
2006-07-11,Lorentz Symmetry Derived from Lorentz Violation in the Bulk,"We consider bulk fields coupled to the graviton in a Lorentz violating
fashion. We expect that the overly tested Lorentz symmetry might set
constraints on the induced Lorentz violation in the brane, and hence on the
dynamics of the interaction of bulk fields on the brane. We also use the
requirement for Lorentz symmetry to constrain the cosmological constant
observed on the brane.",0607043v2
2006-12-12,Impact of Lorentz Violation on Cosmology,"We discuss the impact of Lorentz violation on the cosmology. Firstly, we show
that the Lorentz violation affects the dynamics of the chaotic inflationary
model and gives rise to an interesting feature. Secondly, we propose the
Lorentz violating DGP brane models where the Lorentz violating terms on the
brane accelerate the current universe. We conjecture that the ghost disappears
in the Lorentz violating DGP models.",0612069v1
2004-01-05,Optical cavity tests of Lorentz invariance for the electron,"A hypothetical violation of Lorentz invariance in the electrons' equation of
motion (expressed within the Lorentz-violating extension of the standard model)
leads to a change of the geometry of crystals and thus shifts the resonance
frequency of an electromagnetic cavity. This allows experimental tests of
Lorentz invariance of the electron sector of the standard model. The material
dependence of the effect allows to separate it from an additional shift caused
by Lorentz violation in electrodynamics, and to place independent limits on
both effects. From present experiments, upper limits on Lorentz violation in
the electrons' kinetic energy term are deduced.",0401016v1
2004-09-01,Mixed norm and multidimensional Lorentz spaces,"In the last decade, the problem of characterizing the normability of the
weighted Lorentz spaces has been completely solved (\cite{Sa}, \cite{CaSoA}).
However, the question for multidimensional Lorentz spaces is still open. In
this paper, we consider weights of product type, and give necessary and
sufficient conditions for the Lorentz spaces, defined with respect to the
two-dimensional decreasing rearrangement, to be normable. To this end, it is
also useful to study the mixed norm Lorentz spaces. Finally, we prove
embeddings between all the classical, multidimensional, and mixed norm Lorentz
spaces.",0409018v1
2003-07-28,Derivation of the Lorentz Force Law and the Magnetic Field Concept using an Invariant Formulation of the Lorentz Transformation,"It is demonstrated how the right hand sides of the Lorentz Transformation
equations may be written, in a Lorentz invariant manner, as 4--vector scalar
products. The formalism is shown to provide a short derivation, in which the
4--vector electromagnetic potential plays a crucial role, of the Lorentz force
law of classical electrodynamics, and the conventional definition of the
magnetic field in terms spatial derivatives of the 4--vector potential. The
time component of the relativistic generalisation of the Lorentz force law is
discussed. An important physical distinction between the space-time and
energy-momentum 4--vectors is also pointed out.",0307133v1
2007-08-13,"Local Lorentz Transformation and ""Lorentz Violation""","Some solutions to the anomalies of ultra high energy cosmic-ray(UHECR) and
TeV $\gamma$-rays require disturbed non-quadratic dispersion relations, which
suggest the Lorentz violation. Also, some new theories such as quantum gravity,
string theory and the standard model extension imply the Lorentz violation. In
this paper, we derive some transformation laws for the classical parameters of
nonlinear field system, and then provide their dispersion relations. These
dispersion relations also have non-quadratic form but keep the Lorentz
invariance. The analysis of this paper may be helpful for understanding the
quantum theory and the plausible Lorentz violation.",0708.1643v1
2009-06-01,Lorentz Ricci solitons on 3-dimensional Lie groups,"The three-dimensional Heisenberg group $H_3$ has three left-invariant Lorentz
metrics $g_1$, $g_2$ and $g_3$. They are not isometric each other. In this
paper, we characterize the left-invariant Lorentzian metric $g_1$ as a Lorentz
Ricci soliton. This Ricci soliton $g_1$ is a shrinking non-gradient Ricci
soliton. Likewise we prove that the isometry group of flat Euclid plane E(2)
and the isometry group of flat Lorentz plane E(1,1) have Lorentz Ricci
solitons.",0906.0086v2
2010-10-08,Vector Superfields and Lorentz Violation,"We extend Lorentz-violating Supersymmetry models to include vector
superfields. The CPT-preserving model generalizes easily, while the obvious
attempt at generalizing the CPT-violating model meets serious obstructions.
Generalizations of the CPT-preserving but Lorentz-Violating model to higher
dimensions are also straightforward. Compactification is used to reduce the
six-dimensional theory to an ${\cal{N}} =2$ Lorentz-violating theory in four
dimensions, while the ten-dimensional theory is used to produce an
${\cal{N}}=4$ Lorentz-violating theory. This may be useful in future
constructions involving Ads/CFT correspondence with Lorentz violation.",1010.1781v1
2011-03-05,Orthogonal decomposition of Lorentz transformations,"The canonical decomposition of a Lorentz algebra element into a sum of
orthogonal simple (decomposable) Lorentz bivectors is discussed, as well as the
decomposition of a proper orthochronous Lorentz transformation into a product
of commuting Lorentz transformations, each of which is the exponential of a
simple bivector. As an application, we obtain an alternative method of deriving
the formulas for the exponential and logarithm for Lorentz transformations.",1103.1072v2
2013-10-08,Fidelity of Mobius matrices related with Lorentz boosts,"In this article we consider the extended version of a real counterpart of
qubit density matrices, called the M\""obius matrix, and we see that it is a
normalized Lorentz boost. Using the isomorphic gyrogroup structures between the
set $\PP$ of all Lorentz boosts and the Einstein gyrogroup on the open unit
ball $\B$ of $\R^n$ we give an explicit formula of the fidelity for M\""obius
matrices in terms of Lorentz gamma factors.",1310.1981v1
2015-06-04,Fourier series in weighted Lorentz spaces,"The Fourier coefficient map is considered as an operator from a weighted
Lorentz space on the circle to a weighted Lorentz sequence space. For a large
range of Lorentz indices, necessary and sufficient conditions on the weights
are given for the map to be bounded. In addition, new direct analogues are
given for known weighted Lorentz space inequalities for the Fourier transform.
Applications are given that involve Fourier coefficients of functions in LlogL
and more general Lorentz-Zygmund spaces.",1506.01629v2
2016-05-31,Local Lorentz transformations and Thomas effect in general relativity,"The tetrad method is used for an introduction of local Lorentz frames and a
detailed analysis of local Lorentz transformations. A formulation of equations
of motion in local Lorentz frames is based on the Pomeransky-Khriplovich
gravitoelectromagnetic fields. These fields are calculated in the most
important special cases and their local Lorentz transformations are determined.
The local Lorentz transformations and the Pomeransky-Khriplovich
gravitoelectromagnetic fields are applied for a rigorous derivation of a
general equation for the Thomas effect in Riemannian spacetimes and for a
consideration of Einstein's equivalence principle and the Mathisson force.",1606.00756v2
2016-10-28,Looking for Lorentz Violation in Short-Range Gravity,"General violations of Lorentz symmetry can be described by the Standard-Model
Extension (SME) framework. The SME predicts modifications to existing physics
and can be tested in high-precision experiments. By looking for small
deviations from Newton gravity, short-range gravity experiments are expected to
be sensitive to possible gravitational Lorentz-violation signals. With two
group's short-range gravity data analyzed recently, no nonminimal Lorentz
violation signal is found at the micron distance scale, which gives stringent
constraints on nonminimal Lorentz-violation coefficients in the SME.",1610.09960v1
2017-03-22,Bergman-Lorentz spaces on tube domains over symmetric cones,"We study Bergman-Lorentz spaces on tube domains over symmetric cones, i.e.
spaces of holomorphic functions which belong to Lorentz spaces $L(p, q).$ We
establish boundedness and surjectivity of Bergman projectors from Lorentz
spaces to the corresponding Bergman-Lorentz spaces and real interpolation
between Bergman-Lorentz spaces. Finally we ask a question whose positive answer
would enlarge the interval of parameters $p\in (1, \infty)$ such that the
relevant Bergman projector is bounded on $L^p$ for cones of rank $r\geq 3.$",1703.07859v1
2019-02-14,Lorentz violation and Gravitoelectromagnetism: Casimir effect and Stefan-Boltzmann law at Finite temperature,"The standard model and general relativity are local Lorentz invariants.
However it is possible that at Planck scale there may be a breakdown of Lorentz
symmetry. Models with Lorentz violation are constructed using Standard Model
Extension (SME). Here gravitational sector of the SME is considered to analyze
the Lorentz violation in Gravitoelectromagnetism (GEM). Using the
energy-momentum tensor, the Stefan-Boltzmann law and Casimir effect are
calculated at finite temperature to ascertain the level of local Lorentz
violation. Thermo Field Dynamics (TFD) formalism is used to introduce
temperature effects.",1902.05344v1
2021-04-28,High Order Explicit Lorentz Invariant Volume-preserving Algorithms for Relativistic Dynamics of Charged Particles,"Lorentz invariant structure-preserving algorithms possess
reference-independent secular stability, which is vital for simulating
relativistic multi-scale dynamical processes. The splitting method has been
widely used to construct structure-preserving algorithms, but without exquisite
considerations, it can easily break the Lorentz invariance of continuous
systems. In this paper, we introduce a Lorentz invariant splitting technique to
construct high order explicit Lorentz invariant volume-preserving algorithms
(LIVPAs) for simulating charged particle dynamics. Using this method, long-term
stable explicit LIVPAs with different orders are developed and their
performances of Lorentz invariance and long-term stability are analyzed in
detail.",2104.13513v1
2022-05-05,Lorentz symmetry breaking -- classical and quantum aspects,"In this book, we review various aspects of the Lorentz symmetry breaking,
both classical and quantum ones, with the special interest to perturbative
generation of Lorentz-breaking terms. We present impacts of Lorentz symmetry
breaking in noncommutative and supersymmetric theories. Also, we discuss the
problem of Lorentz symmetry breaking in a curved space-time. The book is closed
with a review of experimental studies of Lorentz symmetry breaking.",2205.02594v3
2004-03-08,Neutrino Oscillations and Lorentz Violation,"Existing experimental data for neutrino oscillations are consistent with
Lorentz-violating massless neutrinos. This talk summarizes some aspects of
neutrino oscillations from the perspective of Lorentz and CPT violation in
effective quantum field theory.",0403088v1
2004-12-29,Lorentz Violation and Gravity,"This talk outlines some results for gravitational theories with local Lorentz
violation in the context of the Lorentz- and CPT-violating Standard-Model
Extension.",0412406v1
2007-03-23,Lorentz violation and neutrino oscillations,"Lorentz violation naturally leads to neutrino oscillations and provides an
alternative mechanism that may explain current data. In this work, we discuss
possible signals of Lorentz violation in neutrino-oscillation experiments.",0703263v1
2005-01-01,Particles and propagators in Lorentz-violating supergravity,"We obtain the propagators for spin 1/2 fermions and sfermions in
Lorentz-violating supergravity.",0501002v1
2004-04-26,On arithmetical and dynamical properties of Lorentz maps of the torus,"We proved that any Lorentz transformation of 2-torus is Anosov automorphism.
One completely describes admissible parameters of Lorentz transformations and
their arithmetical properties. One proved that an admissible speed light
parameter has a countable spectra accumulating to this parameter.",0404464v1
2000-03-27,Deformed Lorentz Symmetry and High-Energy Astrophysics (I),"An updated discussion of Lorentz symmetry violation in particle physics at
very high energy is presented, focusing on applications of models of deformed
Lorentz symmetry to high-energy astrophysics.",0003080v1
2008-02-05,Perspectives on Lorentz and CPT Violation,This talk offers some comments and perspectives on Lorentz and CPT violation.,0802.0581v1
2008-04-09,A realization of the quantum Lorentz group,"A realization of a deformed Lorentz algebra is considered and its irreducible
representations are found; in the limit $q\to 1$, these are precisely the
irreducible representations of the classical Lorentz group.",0804.1529v1
2008-11-26,The Lorentz Condition is Equivalent to Maxwell Equations,"It is shown that the Lorentz condition which is a conservation law on the
electromagnetic four-vector-density A, plus the Lorentz transformation, taken
together, are equivalent to the microscopic Maxwell's equations.",0811.4431v1
2010-08-06,Lorentz Violation and Extended Supersymmetry,"We construct a collection of Lorentz violating Yang-Mills theories exhibiting
supersymmetry.",1008.1279v1
2010-10-04,Probing Lorentz Symmetry with Gravitationally Coupled Matter,"Methods for obtaining additional sensitivities to Lorentz violation in the
fermion sector of the Standard-Model Extension using gravitational couplings
are discussed.",1010.0464v1
2010-10-19,Lorentz Symmetry and Matter-Gravity Couplings,"This proceedings contribution summarizes recent investigations of Lorentz
violation in matter-gravity couplings.",1010.3990v1
2013-07-29,Higher-order Lorentz violation,"This brief review discusses Lorentz-violating operators of arbitrary
dimension within the photon and neutrino sectors of the Standard-Model
Extension.",1307.7969v1
2016-07-25,Nonminimal Lorentz violation,"This contribution to the CPT'16 meeting provides a brief overview of recent
studies of nonminimal Lorentz violation in the Standard-Model Extension.",1607.07693v1
2013-09-15,Comments on Lorentz and CPT Violation,"This contribution to the CPT'13 meeting briefly introduces Lorentz and CPT
violation and outlines two recent developments in the field.",1309.3761v1
2016-05-26,On $M$ -- terms approximations Besov classes in Lorentz spaces,"In this paper we consider Lorentz space with a mixed norm of periodic
functions of many variables. We obtain the exact estimation of the best M-term
approximations of Nikol'ski's, Besov's classes in the Lorentz space with the
mixed norm.",1605.08358v1
2016-08-30,Astroparticles and tests of Lorentz invariance,"Searches for violations of Lorentz invariance using cosmic rays, gamma rays,
and astrophysical neutrinos and the prospects for future tests using cosmic-ray
showers are presented.",1608.08373v1
2016-12-29,Gravitational Searches for Lorentz Violation with Matter and Astrophysics,"This contribution to the CPT'16 proceedings summarizes recent tests of
Lorentz violation in the pure-gravity sector with cosmic rays and reviews
recent progress in matter-gravity couplings.",1612.09264v1
2018-01-26,Ads spacetime in Lorentz covariant gauges,"We show how to generate the AdS spacetime metric in general Lorentz covariant
gauges. In particular we propose an iterative method for solving the Lorentz
gauge.",1801.08838v1
2022-10-18,Concepts in Lorentz and CPT Violation,"This contribution to the CPT'22 meeting provides a brief review of some
concepts in Lorentz and CPT violation.",2210.09824v1
2002-06-27,Initial-amplitude dependence in weakly damped oscillators,"A pedagogically instructive experimental procedure is suggested for
distinguishing between different damping terms in a weakly damped oscillator,
which highclights the connection between non-linear damping and
initial-amplitude dependence. The most common damping terms such as contact
friction, air resistance, viscous drag, and electromagnetic damping have
velocity dependences of the form constant, v, or v^2. The corresponding energy
dependences of the form \sqrt{E}, E, or E\sqrt{E} in the energy loss equation
give rise to characteristic dependence of the amplitude decay slope on the
initial amplitude.",0206086v1
2006-05-22,The entanglement of damped noon-state and its performance in phase measurement,"The state evolution of the initial optical \textit{noon} state is
investigated. The residue entanglement of the state is calculated after it is
damped by amplitude and phase damping. The relative entropy of entanglement of
the damped state is exactly obtained. The performance of direct application of
the damped \textit{noon} state is compared with that of firstly distilling the
docoherence damped state then applying it in measurement.",0605184v1
2007-10-04,Channel-Adapted Quantum Error Correction for the Amplitude Damping Channel,"We consider error correction procedures designed specifically for the
amplitude damping channel. We analyze amplitude damping errors in the
stabilizer formalism. This analysis allows a generalization of the [4,1]
`approximate' amplitude damping code of quant-ph/9704002. We present this
generalization as a class of [2(M+1),M] codes and present quantum circuits for
encoding and recovery operations. We also present a [7,3] amplitude damping
code based on the classical Hamming code. All of these are stabilizer codes
whose encoding and recovery operations can be completely described with
Clifford group operations. Finally, we describe optimization options in which
recovery operations may be further adapted according to the damping probability
gamma.",0710.1052v1
2010-03-24,Dynamical shift condition for unequal mass black hole binaries,"Certain numerical frameworks used for the evolution of binary black holes
make use of a gamma driver, which includes a damping factor. Such simulations
typically use a constant value for damping. However, it has been found that
very specific values of the damping factor are needed for the calculation of
unequal mass binaries. We examine carefully the role this damping plays, and
provide two explicit, non-constant forms for the damping to be used with
mass-ratios further from one. Our analysis of the resultant waveforms compares
well against the constant damping case.",1003.4681v1
2014-02-28,Escape rate for the power-law distribution in low-to-intermediate damping,"Escape rate in the low-to-intermediate damping connecting the low damping
with the intermediate damping is established for the power-law distribution on
the basis of flux over population theory. We extend the escape rate in the low
damping to the low-to-intermediate damping, and get an expression for the
power-law distribution. Then we apply the escape rate for the power-law
distribution to the experimental study of the excited-state isomerization, and
show a good agreement with the experimental value. The extra current and the
improvement of the absorbing boundary condition are discussed.",1402.7194v2
2015-03-21,On damping created by heterogeneous yielding in the numerical analysis of nonlinear reinforced concrete frame elements,"In the dynamic analysis of structural engineering systems, it is common
practice to introduce damping models to reproduce experimentally observed
features. These models, for instance Rayleigh damping, account for the damping
sources in the system altogether and often lack physical basis. We report on an
alternative path for reproducing damping coming from material nonlinear
response through the consideration of the heterogeneous character of material
mechanical properties. The parameterization of that heterogeneity is performed
through a stochastic model. It is shown that such a variability creates the
patterns in the concrete cyclic response that are classically regarded as
source of damping.",1503.07122v1
2016-01-20,Introduction to Landau Damping,"The mechanism of Landau damping is observed in various systems from plasma
oscillations to accelerators. Despite its widespread use, some confusion has
been created, partly because of the different mechanisms producing the damping
but also due to the mathematical subtleties treating the effects. In this
article the origin of Landau damping is demonstrated for the damping of plasma
oscillations. In the second part it is applied to the damping of coherent
oscillations in particle accelerators. The physical origin, the mathematical
treatment leading to the concept of stability diagrams and the applications are
discussed.",1601.05227v1
2011-11-30,Local phase damping of single qubits sets an upper bound on the phase damping rate of entangled states,"I derive an inequality in which the phase damping rates of single qubits set
an upper bound for the phase damping rate of entangled states of many qubits.
The derivation is based on two assumptions: first, that the phase damping can
be described by a dissipator in Lindblad form and, second, that the phase
damping preserves the population of qubit states in a given basis.",1111.7152v2
2012-05-11,Quantum dynamics of the damped harmonic oscillator,"The quantum theory of the damped harmonic oscillator has been a subject of
continual investigation since the 1930s. The obstacle to quantization created
by the dissipation of energy is usually dealt with by including a discrete set
of additional harmonic oscillators as a reservoir. But a discrete reservoir
cannot directly yield dynamics such as Ohmic damping (proportional to velocity)
of the oscillator of interest. By using a continuum of oscillators as a
reservoir, we canonically quantize the harmonic oscillator with Ohmic damping
and also with general damping behaviour. The dynamics of a damped oscillator is
determined by an arbitrary effective susceptibility that obeys Kramers-Kronig
relations. This approach offers an alternative description of nano-mechanical
oscillators and opto-mechanical systems.",1205.2545v1
2018-07-25,Regularity and asymptotic behaviour for a damped plate-membrane transmission problem,"We consider a transmission problem where a structurally damped plate equation
is coupled with a damped or undamped wave equation by transmission conditions.
We show that exponential stability holds in the damped-damped situation and
polynomial stability (but no exponential stability) holds in the
damped-undamped case. Additionally, we show that the solutions first defined by
the weak formulation, in fact have higher Sobolev space regularity.",1807.09730v1
2021-08-04,Nonlinear fluid damping of elastically mounted pitching wings in quiescent water,"We experimentally study the nonlinear fluid damping of a rigid but
elastically mounted pitching wing in the absence of a freestream flow. The
dynamics of the elastic mount are simulated using a cyber-physical system. We
perturb the wing and measure the fluid damping coefficient from damped
oscillations over a large range of pitching frequencies, pitching amplitudes,
pivot locations and sweep angles. A universal fluid damping scaling is proposed
to incorporate all these parameters. Flow fields obtained using particle image
velocimetry are analyzed to explain the nonlinear behaviors of the fluid
damping.",2108.02090v1
2000-05-10,Extremely High Energy and Violation of Lorentz Invariance,"Extremely high-energy(EHE) cosmic rays might provide a chance to check a
violation of the Lorentz symmetry of spacetime. Some theoretical consideration
is described about why the Lorentz symmetry might break-down in EHE phenomena
in this universe. Some models which introduce the violation of the Lorentz
symmetry will be discussed.",0005218v1
2003-04-02,Threshold analyses and Lorentz violation,"In the context of threshold investigations of Lorentz violation, we discuss
the fundamental principle of coordinate invariance, the role of an effective
dynamical framework, and the conditions of positivity and causality. Our
analysis excludes a variety of previously considered Lorentz-breaking
parameters and opens an avenue for viable dispersion-relation investigations of
Lorentz violation.",0304013v1
1998-10-07,CPT and Lorentz Tests in the Standard Model,"A general Lorentz-violating extension of the minimal SU(3) x SU(2) x U(1)
standard model is described, including both CPT-even and CPT-odd terms. Some
theoretical properties and experimental implications are given. The extension
can be regarded as a low-energy limit of a physically relevant
Lorentz-covariant fundamental theory in which spontaneous Lorentz violation
occurs.",9810274v1
2002-12-24,Lorentz Violation and Spacetime Supersymmetry,"Supersymmetry and Lorentz invariance are closely related as both are
spacetime symmetries. Terms can be added to Lagrangians that explicitly break
either supersymmetry or Lorentz invariance. It is possible to include terms
which violate Lorentz invariance but maintain invariance under supersymmetric
transformations. I illustrate this with some simple extensions of the original
Wess-Zumino model.",0212353v1
2004-11-10,QED Tests of Lorentz Symmetry,"A status report is given of some recent theoretical and experimental
investigations looking for signals of Lorentz violation in QED. Experiments
with light, charged particles, and atoms have exceptional sensitivity to small
shifts in energy caused by Lorentz violation, including effects that could
originate from new physics at the Planck scale.",0411149v1
2004-12-22,Lorentz Violation in Supersymmetric Field Theories,"Broken spacetime symmetries might emerge from a fundamental physical theory.
The effective low-energy theory might be expected to exhibit violations of
supersymmetry and Lorentz invariance. Some illustrative models which combine
supersymmetry and Lorentz violation are described, and a superspace formulation
is given.",0412351v1
2003-08-05,Superfield Realizations of Lorentz and CPT Violation,"Superfield realizations of Lorentz-violating extensions of the Wess-Zumino
model are presented. These models retain supersymmetry but include terms that
explicitly break the Lorentz symmetry. The models can be understood as arising
from superspace transformations that are modifications of the familiar one in
the Lorentz-symmetric case.",0308036v1
2003-11-05,Lorentz covariant field theory on noncommutative spacetime based on DFR algebra,"Lorentz covariance is the fundamental principle of every relativistic field
theory which insures consistent physical descriptions. Even if the space-time
is noncommutative, field theories on it should keep Lorentz covariance. In this
letter, it is shown that the field theory on noncommutative spacetime is
Lorentz covariant if the noncommutativity emerges from the algebra of spacetime
operators described by Doplicher, Fredenhagen and Roberts.",0311035v1
2005-11-20,Lorentz Violation and Faddeev-Popov Ghosts,"We consider how Lorentz-violating interactions in the Faddeev-Popov ghost
sector will affect scalar QED. The behavior depends sensitively on whether the
gauge symmetry is spontaneously broken. If the symmetry is not broken, Lorentz
violations in the ghost sector are unphysical, but if there is spontaneous
breaking, radiative corrections will induce Lorentz-violating and
gauge-dependent terms in other sectors of the theory.",0511200v1
2006-12-19,Algebraic derivation of spectrum of the Dirac Hamiltonian for arbitrary combination of Lorentz-scalar and Lorentz-vector Coulomb potentials,"Spectrum of the Dirac Equation is obtained algebraically for arbitrary
combination of Lorentz-scalar and Lorentz-vector Coulomb potentials using the
Witten's Superalgebra approach. The result coincides with that, known from the
explicit solution of Dirac equation.",0612199v2
1999-10-19,Perturbed Coulomb potentials in the Klein-Gordon equation via the shifted-1 expansion technique,"A shifted - l expansion technique is introduced to calculate the energy
eigenvalues for Klein-Gordon (KG) equation with Lorentz vector and/or Lorentz
scalar potentials. Although it applies to any spherically symmetric potential,
those that include Coulomb-like terms are only considered. Exact eigenvalues
for a Lorentz vector or a Lorentz scalar, and an equally mixed Lorentz vector
and Lorenz scalar Coulombic potentials are reproduced. Highly accurate and
rapidly converging ground-state energies for Lorentz vector Coulomb with a
Lorentz scalar linear potential, V(r)=-A1/r+kr, and S(r)=kr, respectively, are
obtained. Moreover, a simple straightforward closed-form solution for a
KG-particle in a Coulombic Lorentz vector and Lorentz scalar potentials is
presented in appendix A.",9910028v1
2008-04-01,"Lorentz Violation, Electrodynamics, and the Cosmic Microwave Background","Vacuum birefringence is a signature of Lorentz-symmetry violation. Here we
report on a recent search for birefringence in the cosmic microwave background.
Polarization data is used to place constraints on certain forms of Lorentz
violation.",0804.0269v1
2008-12-11,Lorentz Violation and Alpha-Decay,"Relating the effective Lorentz violation coefficients for composite particles
to the coefficients for their constituent fields is a challenging problem. We
calculate the Lorentz violation coefficients relevant to the dynamics of an
alpha-particle in terms of proton and neutron coefficients. The alpha-particle
coefficients would lead to anisotropies in the alpha-decays of nuclei, and
because the decay process involves quantum tunneling, the effects of any
Lorentz violations could be exponentially enhanced.",0812.2236v1
2013-07-22,Lorentz Breaking and Gravity,"Gravitational theories with Lorentz violation must account for a number of
possible features in order to be consistent theoretically and
phenomenologically. A brief summary of these features is given here. They
include evasion of a no-go theorem, connections between spontaneous Lorentz
breaking and diffeomorphism breaking, the appearance of massless
Nambu-Goldstone modes and massive Higgs modes, and the possibility of a Higgs
mechanism in gravity.",1307.5722v1
2014-11-26,Geometry of world sheets in Lorentz-Minkowski space,"A world sheet in Lorentz-Minkowski space is a timelike submanifold consisting
of a one-parameter family of spacelike submanifolds in Lorentz-Minkowski space.
In this paper we investigate differential geometry of world sheets in
Lorentz-Minkowski space as an application of the theory of big wave fronts.",1411.7219v1
2016-09-22,Lorentz Covariant Canonical Symplectic Algorithms for Dynamics of Charged Particles,"In this paper, the Lorentz covariance of algorithms is introduced. Under
Lorentz transformation, both the form and performance of a Lorentz covariant
algorithm are invariant. To acquire the advantages of symplectic algorithms and
Lorentz covariance, a general procedure for constructing Lorentz covariant
canonical symplectic algorithms (LCCSA) is provided, based on which an explicit
LCCSA for dynamics of relativistic charged particles is built. LCCSA possesses
Lorentz invariance as well as long-term numerical accuracy and stability, due
to the preservation of discrete symplectic structure and Lorentz symmetry of
the system. For situations with time-dependent electromagnetic fields, which is
difficult to handle in traditional construction procedures of symplectic
algorithms, LCCSA provides a perfect explicit canonical symplectic solution by
implementing the discretization in 4-spacetime. We also show that LCCSA has
built-in energy-based adaptive time steps, which can optimize the computation
performance when the Lorentz factor varies.",1609.07019v1
2019-05-26,Lorentz Violation and Riemann-Finsler Geometry,"The general charge-conserving effective scalar field theory incorporating
violations of Lorentz symmetry is presented. The dispersion relation is used to
infer the effects of spin-independent Lorentz violation on point-particle
motion. A large class of associated Finsler spaces is derived, and the
properties of these spaces is explored.",1905.11562v1
2016-11-07,Signals for Lorentz and CPT Violation in Atomic Spectroscopy Experiments and Other Systems,"The prospects of studying nonminimal operators for Lorentz violation using
spectroscopy experiments with light atoms and muon spin-precession experiments
are presented. Possible improvements on bounds on minimal and nonminimal
operators for Lorentz violation are discussed.",1611.01870v1
2008-07-12,Atomic and optical tests of Lorentz symmetry,"This article reports on the Fourth Meeting on Lorentz and CPT Symmetry, CPT
'07, held in August 2007 in Bloomington, Indiana, USA. The focus is on recent
tests of Lorentz symmetry using atomic and optical physics. Results presented
at the meeting include improved bounds on Lorentz violation in the photon
sector, and the first bounds on several coefficients in the gravity sector.",0807.1998v1
2012-04-25,"CPT, Lorentz invariance, mass differences, and charge non-conservation","A non-local field theory which breaks discrete symmetries, including C, P,
CP, and CPT, but preserves Lorentz symmetry, is presented. We demonstrate that
at one-loop level the masses for particle and antiparticle remain equal due to
Lorentz symmetry only. An inequality of masses implies breaking of the Lorentz
invariance and non-conservation of the usually conserved charges.",1204.5612v1
2016-08-04,Extending the graviton propagator with a Lorentz-violating vector field,"I discuss progress towards ""bootstrapping"" a Lorentz-violating gravity
theory: namely, extending a linear Lorentz-violating theory of a rank-2 tensor
to a non-linear theory by coupling this field to its own stress-energy tensor.",1608.01642v1
2020-01-12,The sharp higher order Lorentz--Poincaré and Lorentz--Sobolev inequalities in the hyperbolic spaces,"In this paper, we study the sharp Poincar\'e inequality and the Sobolev
inequalities in the higher order Lorentz--Sobolev spaces in the hyperbolic
spaces. These results generalize the ones obtained in \cite{Nguyen2020a} to the
higher order derivatives and seem to be new in the context of the
Lorentz--Sobolev spaces defined in the hyperbolic spaces.",2001.03950v1
2020-09-02,Developments in Lorentz and CPT Violation,"This talk at the CPT'19 meeting outlines a few recent developments in Lorentz
and CPT violation, with particular attention to results obtained by researchers
at the Indiana University Center for Spacetime Symmetries.",2009.01107v1
2022-06-13,The unambiguous Lorentz-violating induced terms,"In this work, we show that surface terms, which map dependence on
regularization, can be fixed requiring momentum routing invariance of tadpoles
or diagrams with more external legs. This condition makes the Lorentz-violating
terms induced by quantum corrections determined and uniques.",2206.06353v1
2022-10-01,The Lorentz Process with a Nearly Periodic Distribution of Scatterers,"We consider the Lorentz gas in a distribution of scatterers which
microscopically converges to a periodic distribution, and prove that the
Lorentz gas in the low density limit satisfies a linear Boltzmann equation.
This is in contrast with the periodic Lorentz gas, which does not satisfy the
Boltzmann equation in the limit.",2210.00234v1
2023-01-30,Massive Gravity and Lorentz Symmetry,"We consider Lorentz-symmetry properties of the ghost-free massive gravity
theory proposed by de Rham, Gabadadze, and Tolley. In particular, we present
potentially observable effects in gravitational-wave propagation and in
Newton's law, including Lorentz-violating signals.",2301.13180v1
2002-11-03,Damping of coupled phonon--plasmon modes,"The effect of free carriers on dispersion and damping of coupled
phonon-plasmon modes is considered in the long-wave approximation. The electron
and phonon scattering rate as well as Landau damping are taken into account.",0211040v1
2002-02-01,"On ""the authentic damping mechanism"" of the phonon damping model","Some general features of the phonon damping model are presented. It is
concluded that the fits performed within this model have no physical content.",0202006v1
2010-12-20,Global attractors for the one dimensional wave equation with displacement dependent damping,"We study the long-time behavior of solutions of the one dimensional wave
equation with nonlinear damping coefficient. We prove that if the damping
coefficient function is strictly positive near the origin then this equation
possesses a global attractor.",1012.4455v1
2018-01-28,Observations of excitation and damping of transversal oscillation in coronal loops by AIA/SDO,"The excitation and damping of transversal coronal loop oscillations and
quantitative relation between damping time, damping quality (damping time per
period), oscillation amplitude, dissipation mechanism and the wake phenomena
are investigated. The observed time series data with the \textit{Atmospheric
Imaging Assembly} (AIA) telescope on NASA's \textit{Solar Dynamics Observatory}
(SDO) satellite on 2015 March 2, consisting of 400 consecutive images with 12
seconds cadence in the 171 $ \rm{{\AA}}$ pass band is analyzed for evidence of
transversal oscillations along the coronal loops by Lomb-Scargle periodgram. In
this analysis signatures of transversal coronal loop oscillations that are
damped rapidly were found with dominant oscillation periods in the range of
$\rm{P=12.25-15.80}$ minutes. Also, damping times and damping qualities of
transversal coronal loop oscillations at dominant oscillation periods are
estimated in the range of $ \rm{\tau_d=11.76-21.46}$ minutes and $
\rm{\tau_d/P=0.86-1.49}$, respectively. The observational results of this
analysis show that damping qualities decrease slowly with increasing the
amplitude of oscillation, but periods of oscillations are not sensitive
function of amplitude of oscillations. The order of magnitude of the damping
qualities and damping times are in good agreement with previous findings and
the theoretical prediction for damping of kink mode oscillations by dissipation
mechanism. Furthermore, oscillation of loop segments attenuate with time
roughly as $t^{-\alpha}$ that magnitude values of $\alpha$ for 30 different
segments change from 0.51 to 0.75.",1801.09217v1
2000-09-03,Scaling properties of the redshift power spectrum: theoretical models,"We report the results of an analysis of the redshift power spectrum
$P^S(k,\mu)$ in three typical Cold Dark Matter (CDM) cosmological models, where
$\mu$ is the cosine of the angle between the wave vector and the line-of-sight.
Two distinct biased tracers derived from the primordial density peaks of
Bardeen et al. and the cluster-underweight model of Jing, Mo, & B\""orner are
considered in addition to the pure dark matter models. Based on a large set of
high resolution simulations, we have measured the redshift power spectrum for
the three tracers from the linear to the nonlinear regime. We investigate the
validity of the relation - guessed from linear theory - in the nonlinear regime
$$ P^S(k,\mu)=P^R(k)[1+\beta\mu^2]^2D(k,\mu,\sigma_{12}(k)), $$ where $P^R(k)$
is the real space power spectrum, and $\beta$ equals $\Omega_0^{0.6}/b_l$. The
damping function $D$ which should generally depend on $k$, $\mu$, and
$\sigma_{12}(k)$, is found to be a function of only one variable
$k\mu\sigma_{12}(k)$. This scaling behavior extends into the nonlinear regime,
while $D$ can be accurately expressed as a Lorentz function - well known from
linear theory - for values $D > 0.1$. The difference between $\sigma_{12}(k)$
and the pairwise velocity dispersion defined by the 3-D peculiar velocity of
the simulations (taking $r=1/k$) is about 15%. Therefore $\sigma_{12}(k)$ is a
good indicator of the pairwise velocity dispersion. The exact functional form
of $D$ depends on the cosmological model and on the bias scheme. We have given
an accurate fitting formula for the functional form of $D$ for the models
studied.",0009032v2
2003-06-05,"Chandra Discovery of an X-ray jet and Extended X-ray Structure in z=0.63 quasar, B2 0738+313","We have made a 30 ksec Chandra observation of the redshift z=0.63 GPS quasar
B2 0738+313. We detected X-ray emission from the core and have discovered a 200
kpc (projected on the sky) X-ray jet. The X-ray jet is narrow and curves,
following the extended radio structure to the south of the quasar, and ending
with a hot spot at the southernmost part of the radio lobe. The jet has a knot
at ~13 arcsec away from the core. The knot emission is consistent with the
X-rays being created by the inverse Compton scattering of the cosmic microwave
background (CMB) photons and requires jet bulk Lorentz factors of a few
(Gamma_{bulk} ~ 5-7). We discuss the emission mechanisms that may be
responsible for the jet emission. We present new VLA data of the core and jet,
and discuss the relation between the extended radio and X-ray emission.
Extended emission observed in several GPS sources has been interpreted as a
signature of the source past activity, while the GPS source is young and newly
expanded. We argue that B2~0738+313 may be an example of a new class of radio
sources similar to the FRII radio galaxies in their high jet bulk velocities,
but with the powerful GPS-like nucleus.
  B2 0738+313 also has two damped Lyman-alpha systems along the line of sight,
at z_{abs} = 0.0912 and 0.2212. We discuss the possible connection between the
X-ray absorption (7.2+/-0.9 e20 cm(-2)) detected in the ACIS spectrum and these
two intervening absorbers. We also investigate an extended structure within the
central 10 arcsec of the core in the relation to structure seen in the optical.",0306129v1
2007-04-19,Probing non-standard decoherence effects with solar and KamLAND neutrinos,"It has been speculated that quantum gravity might induce a ""foamy"" space-time
structure at small scales, randomly perturbing the propagation phases of
free-streaming particles (such as kaons, neutrons, or neutrinos). Particle
interferometry might then reveal non-standard decoherence effects, in addition
to standard ones (due to, e.g., finite source size and detector resolution.) In
this work we discuss the phenomenology of such non-standard effects in the
propagation of electron neutrinos in the Sun and in the long-baseline reactor
experiment KamLAND, which jointly provide us with the best available probes of
decoherence at neutrino energies E ~ few MeV. In the solar neutrino case, by
means of a perturbative approach, decoherence is shown to modify the standard
(adiabatic) propagation in matter through a calculable damping factor. By
assuming a power-law dependence of decoherence effects in the energy domain
(E^n with n = 0,+/-1,+/-2), theoretical predictions for two-family neutrino
mixing are compared with the data and discussed. We find that neither solar nor
KamLAND data show evidence in favor of non-standard decoherence effects, whose
characteristic parameter gamma_0 can thus be significantly constrained. In the
""Lorentz-invariant"" case n=-1, we obtain the upper limit gamma_0<0.78 x 10^-26
GeV at 95% C.L. In the specific case n=-2, the constraints can also be
interpreted as bounds on possible matter density fluctuations in the Sun, which
we improve by a factor of ~ 2 with respect to previous analyses.",0704.2568v2
2012-08-08,Relaxation of Blazar Induced Pair Beams in Cosmic Voids,"The stability properties of a low density ultra relativistic pair beam
produced in the intergalactic medium by multi-TeV gamma-ray photons from
blazars are analyzed. The problem is relevant for probes of magnetic field in
cosmic voids through gamma-ray observations. In addition, dissipation of such
beams could affect considerably the thermal history of the intergalactic medium
and structure formation. We use a Monte Carlo method to quantify the properties
of the blazar induced electromagnetic shower, in particular the bulk Lorentz
factor and the angular spread of the pair beam generated by the shower, as a
function of distance from the blazar itself. We then use linear and nonlinear
kinetic theory to study the stability of the pair beam against the growth of
electrostatic plasma waves, employing the Monte Carlo results for our
quantitative estimates. We find that the fastest growing mode, like any
perturbation mode with even a very modest component perpendicular to the beam
direction, cannot be described in the reactive regime. Due to the effect of
non-linear Landau damping, which suppresses the growth of plasma oscillations,
the beam relaxation timescale is found significantly longer than the inverse
Compton loss time. Finally, density inhomogeneities associated with cosmic
structure induce loss of resonance between the beam particles and plasma
oscillations, strongly inhibiting their growth. We conclude that relativistic
pair beams produced by blazars in the intergalactic medium are stable on
timescales long compared to the electromagnetic cascade's. There appears to be
little or no effect of pair-beams on the intergalactic medium.",1208.1761v3
2017-03-02,Pinch dynamics in a low-$β$ plasma,"The relaxation of a helical magnetic field ${\bf B}({\bf x}, t)$ in a
high-conductivity plasma contained in the annulus between two perfectly
conducting coaxial cylinders is considered. The plasma is of low density and
its pressure is negligible compared with the magnetic pressure; the flow of the
plasma is driven by the Lorentz force and and energy is dissipated primarily by
the viscosity of the medium. The axial and toroidal fluxes of magnetic field
are conserved in the perfect-conductivity limit, as is the mass per unit axial
length. The magnetic field relaxes during a rapid initial stage to a force-free
state, and then decays slowly, due to the effect of weak resistivity $\eta$,
while constrained to remain approximately force-free. Interest centres on
whether the relaxed field may attain a Taylor state; but under the assumed
conditions with axial and toroidal flux conserved inside every cylindrical
Lagrangian surface, this is not possible. The effect of an additional
$\alpha$-effect associated with instabilities and turbulence in the plasma is
therefore investigated in exploratory manner. An assumed pseudo-scalar form of
$\alpha$ proportional to $q\,\eta\, ({\bf j}\cdot {\bf B})$ is adopted, where $
{\bf j}=\nabla\times {\bf B}$ and $q$ is an $\mathcal{O}(1)$ dimensionless
parameter. It is shown that, when $q$ is less that a critical value $q_c$, the
evolution remains smooth and similar to that for $q=0$; but that if $q>q_c$,
negative-diffusivity effects act on the axial component of $\bf B$, generating
high-frequency rapidly damped oscillations and an associated transitory
appearance of reversed axial field. However, the scalar quantity $\gamma={\bf
j}\cdot {\bf B}/B^2$ remains highly non-uniform, so that again the field shows
no sign of relaxing to a Taylor state for which $\gamma$ would have to be
constant.",1703.00708v1
2017-03-06,Differences between Doppler velocities of ions and neutral atoms in a solar prominence,"In astrophysical systems with partially ionized plasma the motion of ions is
governed by the magnetic field while the neutral particles can only feel the
magnetic field's Lorentz force indirectly through collisions with ions. The
drift in the velocity between ionized and neutral species plays a key role in
modifying important physical processes like magnetic reconnection, damping of
magnetohydrodynamic waves, transport of angular momentum in plasma through the
magnetic field, and heating. This paper investigates the differences between
Doppler velocities of calcium ions and neutral hydrogen in a solar prominence
to look for velocity differences between the neutral and ionized species. We
simultaneously observed spectra of a prominence over an active region in H I
397 nm, H I 434 nm, Ca II 397 nm, and Ca II 854 nm using a high dispersion
spectrograph of the Domeless Solar Telescope at Hida observatory, and compared
the Doppler velocities, derived from the shift of the peak of the spectral
lines presumably emitted from optically-thin plasma. There are instances when
the difference in velocities between neutral atoms and ions is significant,
e.g. 1433 events (~ 3 % of sets of compared profiles) with a difference in
velocity between neutral hydrogen atoms and calcium ions greater than 3sigma of
the measurement error. However, we also found significant differences between
the Doppler velocities of two spectral lines emitted from the same species, and
the probability density functions of velocity difference between the same
species is not significantly different from those between neutral atoms and
ions. We interpreted the difference of Doppler velocities as a result of
motions of different components in the prominence along the line of sight,
rather than the decoupling of neutral atoms from plasma.",1703.02132v1
2013-09-12,Magnetohydrodynamics dynamical relaxation of coronal magnetic fields. IV. 3D tilted nulls,"In this paper we study current accumulations in 3D ""tilted"" nulls formed by a
folding of the spine and fan. A non-zero component of current parallel to the
fan is required such that the null's fan plane and spine are not perpendicular.
Our aims are to provide valid magnetohydrostatic equilibria and to describe the
current accumulations in various cases involving finite plasma pressure.To
create our equilibrium current structures we use a full, non-resistive,
magnetohydrodynamic (MHD) code so that no reconnection is allowed. A series of
experiments are performed in which a perturbed 3D tilted null relaxes towards
an equilibrium via real, viscous damping forces. Changes to the initial plasma
pressure and to magnetic parameters are investigated systematically.An
initially tilted fan is associated with a non-zero Lorentz force that drives
the fan and spine to collapse towards each other, in a similar manner to the
collapse of a 2D X-point. In the final equilibrium state for an initially
radial null with only the current perpendicular to the spine, the current
concentrates along the tilt axis of the fan and in a layer about the null point
with a sharp peak at the null itself. The continued growth of this peak
indicates that the system is in an asymptotic regime involving an infinite time
singularity at the null. When the initial tilt disturbance (current
perpendicular to the spine) is combined with a spiral-type disturbance (current
parallel to the spine), the final current density concentrates in three
regions: one on the fan along its tilt axis and two around the spine, above and
below the fan. The increased area of current accumulation leads to a weakening
of the singularity formed at the null. The 3D spine-fan collapse with generic
current studied here provides the ideal setup for non-steady reconnection
studies.",1309.3019v1
2019-04-26,Making light of gravitational-waves,"Mixing between photons and low-mass bosons is well considered in the
literature. The particular case of interest here is with hypothetical
gravitons, as we are concerned with the direct conversion of gravitons into
photons in the presence of an external magnetic field. We examine whether such
a process could produce direct low-frequency radio counterparts to
gravitational-wave events. Our work differs from previous work in the
literature in that we use the results of numerical simulations to demonstrate
that, although a single such event may be undetectable without at least 100000
dipoles, an unresolved gravitational wave background from neutron star mergers
could be potentially detectable with a lunar telescope composed of 1000
elements. This is provided the gravitational wave spectrum only experiences
exponential damping above 80 kHz, a full order of magnitude above the limit
achieved by present simulation results. In addition, the extrapolation cannot
have a power-law slope < -2 (for 100 hours of observation time) and background
and foregrounds must be effectively subtracted to obtain the signal. This does
not make detection impossible, but suggests it may be unlikely. Furthermore,
assuming a potentially detectable spectral scenario we show that, for the case
when no detection is made by a lunar array, a lower bound, competitive with
those from Lorentz-invariance violation, may be placed on the energy-scale of
quantum gravitational effects. The SKA is shown to have very limited prospects
for the detection of either a single merger or a background.",1904.12678v6
2021-12-01,Numerical Study of Cosmic Ray Confinement through Dust Resonant Drag Instabilities,"We investigate the possibility of cosmic ray (CR) confinement by charged dust
grains through resonant drag instabilities (RDIs). We perform
magnetohydrodynamic particle-in-cell simulations of magnetized gas mixed with
charged dust and cosmic rays, with the gyro-radii of dust and GeV CRs on
$\sim\mathrm{AU}$ scales fully resolved. As a first study, we focus on one type
of RDI wherein charged grains drift super-Alfv{\'e}nically, with Lorentz forces
strongly dominating over drag forces. Dust grains are unstable to the RDIs and
form concentrated columns and sheets, whose scale grows until saturating at the
simulation box size. Initially perfectly-streaming CRs are strongly scattered
by RDI-excited Alfv{\'e}n waves, with the growth rate of the CR perpendicular
velocity components equaling the growth rate of magnetic field perturbations.
These rates are well-predicted by analytic linear theory. CRs finally become
isotropized and drift at least at $\sim v_\mathrm{A}$ by unidirectional
Alfv\'{e}n waves excited by the RDIs, with a uniform distribution of the pitch
angle cosine $\mu$ and a flat profile of the CR pitch angle diffusion
coefficient $D_{\mu\mu}$ around $\mu = 0$, without the ""$90$ degree pitch angle
problem."" With CR feedback on the gas included, $D_{\mu\mu}$ decreases by a
factor of a few, indicating a lower CR scattering rate, because the
backreaction on the RDI from the CR pressure adds extra wave damping, leading
to lower quasi-steady-state scattering rates. Our study demonstrates that the
dust-induced CR confinement can be very important under certain conditions,
e.g., the dusty circumgalactic medium around quasars or superluminous galaxies.",2112.00752v2
1999-11-16,Probing supernovae ejecta by Halpha damping wings,"It is predicted that H$\alpha$ emission line at the early nebular epoch of
type II-P supernovae may display robust observational effects of damping wings.
This is illustrated by Monte-Carlo simulations. The strength of damping wing
effects may be used to constrain parameters of the line-emitting zone. An
anomalous redshift, width and red wing of H$\alpha$ revealed by SN 1997D on day
150 are explained in terms of damping wing effects.",9911300v1
2009-01-23,Rheological Interpretation of Rayleigh Damping,"Damping is defined through various terms such as energy loss per cycle (for
cyclic tests), logarithmic decrement (for vibration tests), complex modulus,
rise-time or spectrum ratio (for wave propagation analysis), etc. For numerical
modeling purposes, another type of damping is frequently used : it is called
Rayleigh damping. It is a very convenient way of accounting for damping in
numerical models, although the physical or rheological meaning of this approach
is not clear. A rheological model is proposed to be related to classical
Rayleigh damping : it is a generalized Maxwell model with three parameters. For
moderate damping (<25%), this model perfectly coincide with Rayleigh damping
approach since internal friction has the same expression in both cases and
dispersive phenomena are negligible. This is illustrated by finite element
(Rayleigh damping) and analytical (generalized Maxwell model) results in a
simple one-dimensional case.",0901.3717v1
2009-05-20,"Eigenvalue asymptotics, inverse problems and a trace formula for the linear damped wave equation","We determine the general form of the asymptotics for Dirichlet eigenvalues of
the one-dimensional linear damped wave operator. As a consequence, we obtain
that given a spectrum corresponding to a constant damping term this determines
the damping term in a unique fashion. We also derive a trace formula for this
problem.",0905.3242v1
2015-05-06,Remarks on the asymptotic behavior of the solution of an abstract damped wave equation,"We study an abstract damped wave equation. We prove that the solution of the
damped wave equation becomes closer to the solution of a heat type equation as
time tend to infinity. As an application of our approach, we also study the
asymptotic behavior of the damped wave equation in Euclidean space under the
geometric control condition.",1505.01794v2
2017-02-02,Exponential stability for a coupled system of damped-undamped plate equations,"We consider the transmission problem for a coupled system of undamped and
structurally damped plate equations in two sufficiently smooth and bounded
subdomains. It is shown that, independently of the size of the damped part, the
damping is strong enough to produce uniform exponential decay of the energy of
the coupled system.",1702.00637v1
2017-01-18,Two types of spurious damping forces potentially modeled in numerical seismic nonlinear response history analysis,"The purpose of this paper is to provide practitioners with further insight
into spurious damping forces that can be generated in nonlinear seismic
response history analyses (RHA). The term 'spurious' is used to refer to
damping forces that are not present in an elastic system and appear as
nonlinearities develop: such damping forces are not necessarily intended and
appear as a result of modifications in the structural properties as it yields
or damages due to the seismic action. In this paper, two types of spurious
damping forces are characterized. Each type has often been treated separately
in the literature, but each has been qualified as 'spurious', somehow blurring
their differences. Consequently, in an effort to clarify the consequences of
choosing a particular viscous damping model for nonlinear RHA, this paper shows
that damping models that avoid spurious damping forces of one type do not
necessarily avoid damping forces of the other type.",1701.05092v1
2020-12-05,On Periodical Damping Ratio of a Controlled Dynamical System with Parametric Resonances,"This report provides an interpretation on the periodically varying damping
ratio of a dynamical system with direct control of oscillation or vibration
damping. The principal parametric resonance of the system and a new type of
parametric resonance, named ""zero-th order"" parametric resonance, are
investigated by using the method of multiple scales to find approximate,
analytical solutions of the system, which provide an interpretation on such
damping variations.",2012.02932v1
2017-09-11,Comparison of damping mechanisms for transverse waves in solar coronal loops,"We present a method to assess the plausibility of alternative mechanisms to
explain the damping of magnetohydrodynamic (MHD) transverse waves in solar
coronal loops. The considered mechanisms are resonant absorption of kink waves
in the Alfv\'en continuum, phase-mixing of Alfv\'en waves, and wave leakage.
Our methods make use of Bayesian inference and model comparison techniques. We
first infer the values for the physical parameters that control the wave
damping, under the assumption of a particular mechanism, for typically observed
damping time-scales. Then, the computation of marginal likelihoods and Bayes
factors enable us to quantify the relative plausibility between the alternative
mechanisms. We find that, in general, the evidence is not large enough to
support a single particular damping mechanism as the most plausible one.
Resonant absorption and wave leakage offer the most probable explanations in
strong damping regimes, while phase mixing is the best candidate for
weak/moderate damping. When applied to a selection of 89 observed transverse
loop oscillations, with their corresponding measurements of damping times
scales and taking into account data uncertainties, we find that only in a few
cases positive evidence for a given damping mechanism is available.",1709.03347v1
2019-03-25,Distributed Inter-Area Oscillation Damping Control for Power Systems by Using Wind Generators and Load Aggregators,"This paper investigates the potential of wind turbine generators (WTGs) and
load aggregators (LAs) to provide supplementary damping control services for
low frequency inter-area oscillations (LFOs) through the additional distributed
damping control units (DCUs) proposed in their controllers. In order to provide
a scalable methodology for the increasing number of WTGs and LAs, a novel
distributed control framework is proposed to coordinate damping controllers.
Firstly, a distributed algorithm is designed to reconstruct the system Jacobian
matrix for each damping bus (buses with damping controllers). Thus, the
critical LFO can be identified locally at each damping bus by applying
eigen-analysis to the obtained system Jacobian matrix. Then, if the damping
ratio of the critical LFO is less than a preset threshold, the control
parameters of DCUs will be tuned in a distributed and coordinated manner to
improve the damping ratio and minimize the total control cost at the same time.
The proposed control framework is tested in a modified IEEE 39-bus test system.
The simulation results with and without the proposed control framework are
compared to demonstrate the effectiveness of the proposed framework.",1903.10135v1
2019-08-19,Spectral determinant for the damped wave equation on an interval,"We evaluate the spectral determinant for the damped wave equation on an
interval of length $T$ with Dirichlet boundary conditions, proving that it does
not depend on the damping. This is achieved by analysing the square of the
damped wave operator using the general result by Burghelea, Friedlander, and
Kappeler on the determinant for a differential operator with matrix
coefficients.",1908.06862v1
2020-10-12,Decays rates for Kelvin-Voigt damped wave equations II: the geometric control condition,"We study in this article decay rates for Kelvin-Voigt damped wave equations
under a geometric control condition. We prove that when the damping coefficient
is sufficiently smooth ($C^1$ vanishing nicely) we show that exponential decay
follows from geometric control conditions (see~\cite{BuCh, Te12} for similar
results under stronger assumptions on the damping function).",2010.05614v2
2021-06-09,Grammage of cosmic rays in the proximity of supernova remnants embedded in a partially ionized medium,"We investigate the damping of Alfv\'en waves generated by the cosmic ray
resonant streaming instability in the context of the cosmic ray escape and
propagation in the proximity of supernova remnants. We consider ion-neutral
damping, turbulent damping and non linear Landau damping in the warm ionized
and warm neutral phases of the interstellar medium. For the ion-neutral
damping, up-to-date damping coefficients are used. We investigate in particular
whether the self-confinement of cosmic rays nearby sources can appreciably
affect the grammage. We show that the ion-neutral damping and the turbulent
damping effectively limit the residence time of cosmic rays in the source
proximity, so that the grammage accumulated near sources is found to be
negligible. Contrary to previous results, this also happens in the most extreme
scenario where ion-neutral damping is less effective, namely in a medium with
only neutral helium and fully ionized hydrogen. Therefore, the standard
picture, in which CR secondaries are produced during the whole time spent by
cosmic rays throughout the Galactic disk, need not to be deeply revisited.",2106.04948v1
2021-06-22,Sharp decay rate for the damped wave equation with convex-shaped damping,"We revisit the damped wave equation on two-dimensional torus where the damped
region does not satisfy the geometric control condition. We show that if the
damping vanishes as a H\""older function $|x|^{\beta}$, and in addition, the
boundary of the damped region is strictly convex, the wave is stable at rate
$t^{-1+\frac{2}{2\beta+7}}$, which is better than the known optimal decay rate
$t^{-1+\frac{1}{\beta+3}}$ for strip-shaped dampings of the same H\""older
regularity. Moreover, we show by example that the decay rate is optimal. This
illustrates the fact that the energy decay rate depends not only on the order
of vanishing of the damping, but also on the shape of the damped region. The
main ingredient of the proof is the averaging method (normal form reduction)
developed by Hitrick and Sj\""ostrand (\cite{Hi1}\cite{Sj}).",2106.11782v3
2021-08-09,Effect of stepwise adjustment of Damping factor upon PageRank,"The effect of adjusting damping factor {\alpha}, from a small initial value
{\alpha}0 to the final desired {\alpha}f value, upon then iterations needed for
PageRank computation is observed. Adjustment of the damping factor is done in
one or more steps. Results show no improvement in performance over a fixed
damping factor based PageRank.",2108.04150v1
2021-08-17,"Asymptotic behaviour of the wave equation with nonlocal weak damping, anti-damping and critical nonlinearity","In this paper we prove the existence of the global attractor for the wave
equation with nonlocal weak damping, nonlocal anti-damping and critical
nonlinearity.",2108.07395v2
2023-02-23,Buckling Metamaterials for Extreme Vibration Damping,"Damping mechanical resonances is a formidable challenge in an increasing
number of applications. Many of the passive damping methods rely on using low
stiffness dissipative elements, complex mechanical structures or electrical
systems, while active vibration damping systems typically add an additional
layer of complexity. However, in many cases, the reduced stiffness or
additional complexity and mass render these vibration damping methods
unfeasible. Here, we introduce a method for passive vibration damping by
allowing buckling of the primary load path, which sets an upper limit for
vibration transmission: the transmitted acceleration saturates at a maximum
value, no matter what the input acceleration is. This nonlinear mechanism leads
to an extreme damping coefficient tan delta ~0.23 in our metal
metamaterial|orders of magnitude larger than the linear damping of traditional
lightweight structural materials. We demonstrate this principle experimentally
and numerically in free-standing rubber and metal mechanical metamaterials over
a range of accelerations, and show that bi-directional buckling can further
improve its performance. Buckling metamaterials pave the way towards extreme
vibration damping without mass or stiffness penalty, and as such could be
applicable in a multitude of high-tech applications, including aerospace
structures, vehicles and sensitive instruments.",2302.11968v1
2005-08-26,Damping of MHD turbulence in Solar Flares,"(Abridged) We describe the cascade of plasma waves or turbulence injected,
presumably by reconnection, at scales comparable to the size of a solar flare
loop to scales comparable to particle gyroradii, and evaluate their damping by
various mechanisms. We show that the classical viscous damping is unimportant
for magnetically dominated or low beta plasmas and the primary damping
mechanism is the collisionless damping by the background particles. We show
that the damping rate is proportional to the total random momentum density of
the particles. For solar flare conditions this means that in most flares,
except the very large ones, the damping is dominated by thermal background
electrons. For large flares one requires acceleration of essentially all
background electrons into a nonthermal distribution so that the accelerated
electrons can be important in the damping of the waves. In general, damping by
thermal or nonthermal protons is negligible compared to that of electrons
except for quasi-perpendicular propagating waves or for rare proton dominated
flares with strong nuclear gamma-ray line emission. Using the rate for damping
we determine the critical scale below which the damping becomes important and
the spectrum of the turbulence steepens. This critical scale, however, has
strong dependence on the angle of propagation with respect to the magnetic
field direction. The waves can cascade down to very small scales, such as the
gyroradii of the particles at small angles (quasi-parallel propagation) and
possibly near 90 degree (quasi-perpendicular propagation) giving rise to a
highly anisotropic spectral distribution.",0508567v1
2011-07-27,Constraint damping for the Z4c formulation of general relativity,"One possibility for avoiding constraint violation in numerical relativity
simulations adopting free-evolution schemes is to modify the continuum
evolution equations so that constraint violations are damped away. Gundlach et.
al. demonstrated that such a scheme damps low amplitude, high frequency
constraint violating modes exponentially for the Z4 formulation of General
Relativity. Here we analyze the effect of the damping scheme in numerical
applications on a conformal decomposition of Z4. After reproducing the
theoretically predicted damping rates of constraint violations in the linear
regime, we explore numerical solutions not covered by the theoretical analysis.
In particular we examine the effect of the damping scheme on low-frequency and
on high-amplitude perturbations of flat spacetime as well and on the long-term
dynamics of puncture and compact star initial data in the context of spherical
symmetry. We find that the damping scheme is effective provided that the
constraint violation is resolved on the numerical grid. On grid noise the
combination of artificial dissipation and damping helps to suppress constraint
violations. We find that care must be taken in choosing the damping parameter
in simulations of puncture black holes. Otherwise the damping scheme can cause
undesirable growth of the constraints, and even qualitatively incorrect
evolutions. In the numerical evolution of a compact static star we find that
the choice of the damping parameter is even more delicate, but may lead to a
small decrease of constraint violation. For a large range of values it results
in unphysical behavior.",1107.5539v2
2023-12-14,"Nonlocal damping of spin waves in a magnetic insulator induced by normal, heavy, or altermagnetic metallic overlayer: a Schwinger-Keldysh field theory approach","Understanding spin wave (SW) damping, and how to control it to the point of
being able to amplify SW-mediated signals, is one of the key requirements to
bring the envisaged magnonic technologies to fruition. Even widely used
magnetic insulators with low magnetization damping in their bulk, such as
yttrium iron garnet, exhibit 100-fold increase in SW damping due to inevitable
contact with metallic layers in magnonic circuits, as observed in very recent
experiments [I. Bertelli et al., Adv. Quantum Technol. 4, 2100094 (2021)]
mapping SW damping in spatially-resolved fashion. Here, we provide microscopic
and rigorous understanding of wavevector-dependent SW damping using extended
Landau-Lifshitz-Gilbert equation with nonlocal damping tensor, instead of
conventional local scalar Gilbert damping, as derived from Schwinger-Keldysh
nonequilibrium quantum field theory. In this picture, the origin of nonlocal
magnetization damping and thereby induced wavevector-dependent SW damping is
interaction of localized magnetic moments of magnetic insulator with conduction
electrons from the examined three different types of metallic overlayers --
normal, heavy, and altermagnetic. Due to spin-split energy-momentum dispersion
of conduction electrons in the latter two cases, the nonlocal damping is
anisotropic in spin and space, and it can be dramatically reduced by changing
the relative orientation of the two layers when compared to the usage of normal
metal overlayer.",2312.09140v1
2000-05-28,Recent results in Lorentz and CPT tests,"This talk summarizes some recent experimental constraints on Lorentz and CPT
violation.",0005280v1
1996-07-27,Lorentz gauge and Green's formula in classical electrodynamics,"We dicuss the resolution of initial value problems of electrodynamics in the
Lorentz gauge.",9607205v1
1997-02-24,The Lorentz-Dirac Equation: One More Paradox of Preacceleration,"One more paradox of classical Lorentz-Dirac preaccelerative solution is
found: the formation of the event horizon.",9702177v1
1997-02-27,"The Lorentz-Dirac Equation: the Instability of ""Physical"" Solution","The instability of ""physical"" preaccelerative solution of the Lorentz-Dirac
equation is explicitly shown",9703001v1
2006-04-26,Lorentz Violating Inflation,"We explore the impact of Lorentz violation on the inflationary scenario. More
precisely, we study the inflationary scenario in the scalar-vector-tensor
theory where the vector is constrained to be unit and time like. It turns out
that the Lorentz violating vector affects the dynamics of the chaotic
inflationary model and divides the inflationary stage into two parts; the
Lorentz violating stage and the standard slow roll stage. We show that the
universe is expanding as an exact de Sitter spacetime in the Lorentz violating
stage although the inflaton field is rolling down the potential. Much more
interestingly, we find exact Lorentz violating inflationary solutions in the
absence of the inflaton potential. In this case, the inflation is completely
associated with the Lorentz violation. We also mention some consequences of
Lorentz violating inflation which can be tested by observations.",0604192v1
2007-01-17,Lorentz Covariant Distributions with the Spectral Conditions,"The Lorentz covariant tempered disributions with the supports in the product
of the closed upper light cones are described.",0701153v1
2006-06-06,"Still the ""World's Fastest Derivation of the Lorentz Transformation""","Rothenstein's claim of a ``faster'' derivation of the Lorentz transformation
is not correct.",0606046v1
1995-03-16,q-Deformation of the Lorentz Group,"We describe a q-deformation of the Lorentz group in terms of a q-deformation
of the van der Waerden spinor algebra.",9503008v1
2007-11-15,Conservation laws for a general Lorentz connection,"We derive conservation laws for energy-momentum (canonical and dynamical) and
angular momentum for a general Lorentz connection.",0711.2341v1
2010-07-30,Matrix Models and Lorentz Invariance,The question of Lorentz invariance in the membrane matrix model is addressed,1007.5505v1
2011-09-24,Proof of a Lorentz and Levi-Civita thesis,"A formal proof of the thesis by Lorentz and Levi-Civita that the left-hand
side of Einstein field equations represents the real energy-momentum-stress
tensor of the gravitational field.",1109.5268v1
2018-04-23,Lorentz Dynamics on Closed 3-Manifolds,"In this paper, we give a complete topological, as well as geometrical
classification of closed 3-dimensional Lorentz manifolds admitting a noncompact
isometry group.",1804.08695v1
2013-09-03,Hidden Lorentz symmetry of the Horava - Lifshitz gravity,"In this letter it is shown that the Horava-Lifshitz gravity theory admits
Lorentz symmetry preserving preferred global time foliation of the spacetime.",1309.0629v1
2016-05-05,Lorentz-invariant and Lorentz-non-invariant aspects of a scalar tachyon field Lagrangian and the scalar tachyon Feynman propagator,"A consistent theory of faster-than-light particles (tachyons) can be built
replacing the standard Lorentz-invariant approach to the quantum field theory
of tachyons by the Lorentz-covariant one, invoking a concept of the preferred
reference frame. This is a mandatory condition imposed by the causality
conservation. In this article some features of a Lorentz-violating (but
Lorentz-covariant) Lagrangian of a scalar tachyon field are considered. It is
shown that the equation of motion and Feynman propagator resulting from it are
Lorentz-invariant, while the Lorentz symmetry of the suggested tachyon field
model can be defined as covariantly broken.",1605.03425v7
2021-04-24,Random Euclidean embeddings in finite dimensional Lorentz spaces,"Quantitative bounds for random embeddings of $\mathbb{R}^{k}$ into Lorentz
sequence spaces are given, with improved dependence on $\varepsilon$.",2104.11974v1
2021-11-20,Canonical Coordinates and Natural Equation for Lorentz Surfaces in $\mathbb R^3_1$,"We consider Lorentz surfaces in $\mathbb R^3_1$ satisfying the condition
$H^2-K\neq 0$, where $K$ and $H$ are the Gauss curvature and the mean
curvature, respectively, and call them Lorentz surfaces of general type. For
this class of surfaces we introduce special isotropic coordinates, which we
call canonical, and show that the coefficient $F$ of the first fundamental form
and the mean curvature $H$, expressed in terms of the canonical coordinates,
satisfy a special integro-differential equation which we call a natural
equation of the Lorentz surfaces of general type. Using this natural equation
we prove a fundamental theorem of Bonnet type for Lorentz surfaces of general
type. We consider the special cases of Lorentz surfaces of constant non-zero
mean curvature and minimal Lorentz surfaces. Finally, we give examples of
Lorentz surfaces illustrating the developed theory.",2111.10599v1
2023-07-21,Ascent and Descent of Composition Operators on Orlicz-lorentz space,"The aim of this paper is to discuss the characterizations of the composition
operators on Orlicz-Lorentz space to have finite ascent (or descent).",2307.11676v1
2001-12-07,Relativistic Gravity With a Dynamical Preferred Frame,"While general relativity possesses local Lorentz invariance, both canonical
quantum gravity and string theory suggest that Lorentz invariance may be broken
at high energies. Broken Lorentz invariance has also been postulated as an
explanation for astrophysical anomalies such as the missing GZK cutoff.
Therefore, we seek an effective field theory description of gravity where
Lorentz invariance is broken. We will construct a candidate theory and then
briefly discuss some of the implications.",0112012v1
2005-06-06,On the local Lorentz invariance in N=1 supergravity,"We discuss the local Lorentz invariance in the context of N=1 supergravity
and show that a previous attempt to find explicit solutions to the Lorentz
constraint in terms of $\gamma-$matrices is not correct. We improve that
solution by using a different representation of the Lorentz operators in terms
of the generators of the rotation group, and show its compatibility with the
matrix representation of the fermionic field. We find the most general wave
functional that satisfies the Lorentz constraint in this representation.",0506038v1
1998-10-13,Testing CPT and Lorentz Symmetry with Neutral-Meson Oscillations and QED Experiments,"This talk summarizes some theoretical features and experimental implications
of a general Lorentz-violating extension of the minimal SU(3) x SU(2) x U(1)
standard model that allows for both CPT-even and CPT-odd effects. The theory
would arise as the low-energy limit of a fundamental theory that is Lorentz and
CPT covariant but in which spontaneous Lorentz breaking occurs. The use of
neutral-meson oscillations and various QED systems to bound the apparent CPT
and Lorentz violations is described.",9810352v1
1999-08-30,Constraints on Lorentz violation from clock-comparison experiments,"Constraints from clock-comparison experiments on violations of Lorentz and
CPT symmetry are investigated in the context of a general Lorentz-violating
extension of the standard model. The experimental signals are shown to depend
on the atomic and ionic species used as clocks. Certain experiments usually
regarded as establishing comparable bounds are in this context sensitive to
different types of Lorentz violation. Some considerations relevant to possible
future measurements are presented. All these experiments are potentially
sensitive to Lorentz-violating physics at the Planck scale.",9908504v1
2004-05-18,Tests of Lorentz invariance using hydrogen molecules,"We discuss the consequences of Lorentz violation (as expressed within the
Lorentz-violating extension of the standard model) for the hydrogen molecule,
which represents a generic model of a molecular binding. Lorentz-violating
shifts of electronic, vibrational and rotational energy levels, and of the
internuclear distance are calculated. This offers the possibility of obtaining
improved bounds on Lorentz invariance by experiments using molecules.",0405177v2
2004-06-23,Lorentz Violation and Short-Baseline Neutrino Experiments,"A general discussion is given of signals for broken Lorentz symmetry in
short-baseline neutrino experiments. Among the effects that Lorentz violation
can introduce are a dependence on energy differing from that of the usual
massive-neutrino solution and a dependence on the direction of neutrino
propagation. Using the results of the LSND experiment, explicit analysis of the
effects of broken Lorentz symmetry yields a nonzero value (3+/-1) x 10^{-19}
GeV for a combination of coefficients for Lorentz violation. This lies in the
range expected for effects originating from the Planck scale in an underlying
unified theory.",0406255v1
2004-09-21,Nonrelativisitic Ideal Gasses and Lorentz Violations,"We develop statistical mechanics for a nonrelativisitic ideal gas in the
presence of Lorentz violating background fields. The analysis is performed
using the Standard-Model Extension (SME). We derive the corresponding laws of
thermodynamics and find that, to lowest order in Lorentz violation, the scalar
thermodynamic variables are corrected by a rotationally invariant combination
of the Lorentz terms which can be interpreted in terms of a (frame dependent)
effective mass. We find that spin couplings can induce a temperature
independent polarization in the gas that is not present in the conventional
case.",0409252v1
2006-09-08,One-Loop Renormalization of Pure Yang-Mills with Lorentz Violation,"The explicit one-loop renormalizability of pure Yang-Mills theory with
Lorentz violation is demonstrated. The result is consistent with multiplicative
renormalization as the required counter terms are consistent with a single
re-scaling of the Lorentz-violation parameters. In addition, the resulting beta
functions indicate that the CPT-even Lorentz-violating terms increase with
energy scale in opposition to the asymptotically free gauge coupling and
CPT-odd terms. The calculations are performed at lowest-order in the
Lorentz-violating terms as they are assumed small.",0609084v1
2006-11-13,CPT- and Lorentz-symmetry breaking: a review,"The breakdown of spacetime symmetries has recently been identified as a
promising candidate signal for underlying physics, possibly arising through
quantum-gravitational effects. This talk gives an overview over various aspects
of CPT- and Lorentz-violation research. Particular emphasis is given to the
interplay between CPT, Lorentz, and translation symmetry, mechanisms for CPT
and Lorentz breaking, and the construction of a low-energy quantum-field
description of such effect. This quantum field framework, called the SME, is
employed to determine possible phenomenological consequences of CPT and Lorentz
violation for neutral-meson interferometry.",0611177v2
2002-01-29,Some Considerations Regarding Lorentz-Violating Theories,"We investigate the compatibility of Lorentz-violating quantum field theories
with the requirements of causality and stability. A general renormalizable
model for free massive fermions indicates that these requirements are satisfied
at low energies provided the couplings controlling the breaking are small.
However, for high energies either microcausality or energy positivity or both
are violated in some observer frame. We find evidence that this difficulty can
be avoided if the model is interpreted as a sub-Planckian approximation
originating from a nonlocal theory with spontaneous Lorentz violation. The
present study thereby supports the validity of the standard-model extension as
the low-energy limit of any realistic string theory that exhibits spontaneous
Lorentz breaking.",0201238v1
2004-04-04,A note on the dimensional regularization of the Standard Model coupled with Quantum Gravity,"In flat space, gamma5 and the epsilon tensor break the dimensionally
continued Lorentz symmetry, but propagators have fully Lorentz invariant
denominators. When the Standard Model is coupled with quantum gravity gamma5
breaks the continued local Lorentz symmetry. I show how to deform the Einstein
lagrangian and gauge-fix the residual local Lorentz symmetry so that the
propagators of the graviton, the ghosts and the BRST auxiliary fields have
fully Lorentz invariant denominators. This makes the calculation of Feynman
diagrams more efficient.",0404032v2
2004-12-10,Infinitesimally Nonlocal Lorentz Violation,"We introduce a new Lorentz-violating modification to a scalar quantum field
theory. This interaction, while super-renormalizable by power counting, is
fundamentally different from the interactions previously considered within the
Lorentz-violating standard model extension. The Lagrange density is nonlocal,
because of the presence of a Hilbert transform term; however, this nonlocality
is also very weak. The theory has reasonable stability and causality properties
and, although the Lorentz-violating interaction possesses a single vector
index, the theory is nonetheless CPT even. As an application, we analyze the
possible effects of this new form of Lorentz violation on neutral meson
oscillations. We find that under certain circumstances, the interaction may
lead to quite peculiar sidereal modulations in the oscillation frequency.",0412113v1
1994-12-19,Boyd Indices of Orlicz-Lorentz Space,"Orlicz-Lorentz spaces provide a common generalization of Orlicz spaces and
Lorentz spaces. In this paper, we investigate their Boyd indices. Bounds on the
Boyd indices in terms of the Matuszewska-Orlicz indices of the defining
functions are given. Also, we give an example to show that the Boyd indices and
Zippin indices of an Orlicz-Lorentz space need not be equal, answering a
question of Maligranda. Finally, we show how the Boyd indices are related to
whether an Orlicz-Lorentz space is p-convex or q-concave.",9412215v2
2003-01-13,Homogeneous Spaces of the Lorentz Group,"We present a classification, up to isomorphisms, of all the homogeneous
spaces of the Lorentz group with dimension lower than six. At the same time, we
classify, up to conjugation, all the non-discrete closed subgroup of the
Lorentz group and all the subalgebras of the Lorentz Lie algebra. We also study
the covariant mappings between some pairs of homogeneous spaces. This exercise
is done without any claim of originality, but with the hope of providing a
useful instrument for the investigation of the Lorentz transformation
properties of some physical quantities.",0301014v2
2000-07-18,New Clock Comparison Tests of Lorentz Symmetry,"We present two new measurements constraining Lorentz and CPT violation using
the Xe-129 / He-3 Zeeman maser and atomic hydrogen masers. Experimental
investigations of Lorentz and CPT symmetry provide important tests of the
framework of the standard model of particle physics and theories of gravity.
The two-species Xe-129 / He-3 Zeeman maser bounds violations of CPT and Lorentz
symmetry of the neutron at the 10^-31 GeV level. Measurements with atomic
hydrogen masers provide a clean limit of CPT and Lorentz symmetry violation of
the proton at the 10^-27 GeV level.",0007062v1
2007-07-22,Cosmological Particle Creation in the Presence of Lorentz Violation,"In recent years, the effects of Lorentz symmetry breaking in cosmology has
attracted considerable amount of attention. In cosmological context several
topics can be affected by Lorentz violation,e.g., inflationary scenario, CMB,
dark energy problem and barryogenesis. In this paper we consider the
cosmological particle creation due to Lorentz violation (LV). We consider an
exactly solvable model for finding the spectral properties of particle creation
in an expanding space-time exhibiting Lorentz violation. In this model we
calculate the spectrum and its variations with respect to the rate and the
amount of space-time expansion.",0707.3247v1
2007-09-04,Causal sets and conservation laws in tests of Lorentz symmetry,"Many of the most important astrophysical tests of Lorentz symmetry also
assume that energy-momentum of the observed particles is exactly conserved. In
the causal set approach to quantum gravity a particular kind of Lorentz
symmetry holds but energy-momentum conservation may be violated. We show that
incorrectly assuming exact conservation can give rise to a spurious signal of
Lorentz symmetry violation for a causal set. However, the size of this spurious
signal is much smaller than can be currently detected and hence astrophysical
Lorentz symmetry tests as currently performed are safe from causal set induced
violations of energy-momentum conservation.",0709.0539v2
2007-12-12,One-Loop Renormalization of QCD with Lorentz Violation,"The explicit one-loop renormalizability of the gluon sector of QCD with
Lorentz violation is demonstrated. The result is consistent with multiplicative
renormalization as the required counter terms are consistent with a single
re-scaling of the Lorentz-violation parameters. In addition, the resulting beta
functions indicate that the CPT-even Lorentz-violating terms increase with
energy scale in opposition to the asymptotically free gauge coupling and
CPT-odd terms. The calculations are performed at lowest-order in the
Lorentz-violating terms as they are assumed small.",0712.2055v1
2009-03-02,K-essence Explains a Lorentz Violation Experiment,"Recently, a state of the art experiment shows evidence for Lorentz violation
in the gravitational sector. To explain this experiment, we investigate a
spontaneous Lorentz violation scenario with a generalized scalar field. We find
that when the scalar field is nonminimally coupled to gravity, the Lorentz
violation induces a deformation in the Newtonian potential along the direction
of Lorentz violation.",0903.0227v3
2009-10-23,Free energy of Lorentz-violating QED at high temperature,"In this paper we study the one- and two-loop contribution to the free energy
in QED with the Lorentz symmetry breaking introduced via constant CPT-even
Lorentz-breaking parameters at the high temperature limit. We find the impact
of the Lorentz-violating term for the free energy and carry out a numerical
estimation for the Lorentz-breaking parameter.",0910.4560v2
2010-04-26,Asymptotic behavior of Lorentz violation on orbifolds,"Momentum dependence of quantum corrections with higher-dimensional Lorentz
violation is examined in electrodynamics on orbifolds. It is shown that effects
of the Lorentz violation are not decoupled at high energy scales. Despite the
loss of the higher-dimensional Lorentz invariance, a higher-dimensional Ward
identity is found to be fulfilled for one-loop vacuum polarization. This
implies that gauge invariance may be prior to Lorentz invariance as a guiding
principle in higher-dimensional field theory. As a universal application of
electrodynamics, an extra-dimensional aspect for Furry's theorem is emphasized.",1004.4410v1
2011-06-30,An Osserman-type condition on $g.f.f$-manifolds with Lorentz metric,"A condition of Osserman type, called $\phi$-null Osserman condition, is
introduced and studied in the context of Lorentz globally framed $f$-manifolds.
An explicit example shows the naturalness of this condition in the setting of
Lorentz $\mathcal{S}$-manifolds. We prove that a Lorentz $\mathcal{S}$-manifold
with constant $\phi$-sectional curvature is $\phi$-null Osserman, extending a
result stated for Lorentz Sasaki space forms. Then we state some
characterizations for a particular class of $\phi$-null Osserman
$\cal{S}$-manifolds. Finally, some examples are examined.",1106.6317v2
2011-09-29,Superluminal neutrino and spontaneous breaking of Lorentz invariance,"Generally speaking, the existence of a superluminal neutrino can be
attributed either to re-entrant Lorentz violation at ultralow energy from
intrinsic Lorentz violation at ultrahigh energy or to spontaneous breaking of
fundamental Lorentz invariance (possibly by the formation of a fermionic
condensate). Re-entrant Lorentz violation in the neutrino sector has been
discussed elsewhere. Here, the focus is on mechanisms of spontaneous symmetry
breaking.",1109.6624v4
2012-06-08,A realisation of Lorentz algebra in Lorentz violating theory,"A Lorentz non-invariant higher derivative effective action in flat spacetime,
characterised by a constant vector, can be made invariant under infinitesimal
Lorentz transformations by restricting the allowed field configurations. These
restricted fields are defined as functions of the background vector in such a
way that background dependance of the dynamics of the physical system is no
longer manifest. We show here that they also provide a field basis for the
realisation of Lorentz algebra and allow the construction of a Poincar\'e
invariant symplectic two form on the covariant phase space of the theory.",1206.1695v2
2012-10-04,QED with chiral nonminimal coupling: aspects of the Lorentz-violating quantum corrections,"An effective model for QED with the addition of a nonminimal coupling with a
chiral character is investigated. This term, which is proportional to a fixed
4-vector $b_\mu$, violates Lorentz symmetry and may originate a CPT-even
Lorentz breaking term in the photon sector. It is shown that this Lorentz
breaking CPT-even term is generated and that,in addition, the chiral nonminimal
coupling requires this term is present from the beginning. The
nonrenormalizability of the model is invoked in the discussion of this fact and
the result is confronted with the one from a model with a Lorentz-violating
nonminimal coupling without chirality.",1210.1552v1
2013-04-24,Aspects of Electrodynamics Modified by Some Dimension-five Lorentz Violating Interactions,"Assuming Lorentz symmetry is broken by some fixed vector background, we study
the spinor electrodynamics modified by two dimension-five Lorentz-violating
interactions between fermions and photons. The effective polarization and
magnetization are identified from the modified Maxwell equations, and the
theoretical consequences are investigated. We also compute the corrections to
the relativistic energy levels of hydrogen atom induced by these
Lorentz-violating operators in the absence and presence of uniform external
fields in first-order perturbation theory. We find that the hydrogen spectrum
is insensitive to the breakdown of Lorentz boost symmetry.",1304.6484v2
2013-07-15,Classification of minimal Lorentz surfaces in indefinite space forms with arbitrary codimension and arbitrary index,"Since J. L. Lagrange initiated in 1760 the study of minimal surfaces of
Euclidean 3-space, minimal surfaces in real space forms have been studied
extensively by many mathematicians during the last two and half centuries. In
contrast, so far very few results on minimal Lorentz surfaces in indefinite
space forms are known. Hence, in this paper we investigate minimal Lorentz
surfaces in arbitrary indefinite space forms. As a consequence, we obtain
several classification results for minimal Lorentz surfaces in indefinite space
forms. In particular, we completely classify all minimal Lorentz surfaces in a
pseudo-Euclidean space $\mathbb E^m_s$ with arbitrary dimension $m$ and
arbitrary index $s$.",1307.3969v1
2016-07-12,The Impact of Lorentz Violation on the Klein Tunneling Effect,"We discuss the impact of a tiny Lorentz-violating $b^\mu$ term on the one
dimensional motion of a Dirac particle scattering on a rectangular barrier. We
assume the experiment is performed in a particular inertial frame, where the
components of $b^\mu$ are assumed constants. The results show that
Lorentz-violation modification to the transmission rate depends on the observer
Lorentz nature of $b^\mu$. For a spacelike or lightlike $b^\mu$ the induced
resonant frequency shift depends on the polarization, while for timelike
$b^\mu$ there is essentially no modification.",1607.03749v1
2016-07-27,Strongly Enhanced Effects of Lorentz-Symmetry Violation in Yb$^+$ and Highly Charged Ions,"A Lorentz-symmetry test with Ca$^+$ ions demonstrated the potential of using
quantum information inspired technology for tests of fundamental physics. A
systematic study of atomic-system sensitivities to Lorentz violation identified
the ytterbium ion as an ideal system with high sensitivity as well as excellent
experimental controllability. A test of Lorentz-violating physics in the
electron-photon sector with Yb$^+$ ions has the potential to reach levels of
10$^{-23}$, five orders of magnitude more sensitive than the current best
bounds. Similar sensitivities may be also reached with highly charged ions.",1607.07932v1
2018-05-16,Sequence Lorentz spaces and their geometric structure,"This article is dedicated to geometric structure of the Lorentz and
Marcinkiewicz spaces in case of the pure atomic measure. We study complete
criteria for order continuity, the Fatou property, strict monotonicity and
strict convexity in the sequence Lorentz spaces $\gamma_{p,w}$. Next, we
present a full characterization of extreme points of the unit ball in the
sequence Lorentz space $\gamma_{1,w}$. We also establish a complete description
with an isometry of the dual and predual spaces of the sequence Lorentz spaces
$\gamma_{1,w}$ written in terms of the Marcinkiewicz spaces. Finally, we show a
fundamental application of geometric structure of $\gamma_{1,w}$ to
one-complemented subspaces of $\gamma_{1,w}$.",1805.06355v1
2013-09-17,BPS Maxwell-Chern-Simons-like vortices in a Lorentz-violating framework,"We have analyzed Maxwell-Chern-Simons-Higgs BPS vortices in a
Lorentz-violating CPT-odd context. The Lorentz violation induces profiles with
a conical behavior at the origin. For some combination of the coefficients for
Lorentz violation there always exists a sufficiently large winding number for
which the magnetic field flips its sign.",1309.4247v1
2016-05-17,Are Maxwell's equations Lorentz-covariant?,"The statement that Maxwell's electrodynamics in vacuum is already covariant
under Lorentz transformations is commonplace in the literature. We analyse the
actual meaning of that statement and demonstrate that Maxwell's equations are
perfectly fit to be Lorentz-covariant; they become Lorentz-covariant if we
construct to be so, by postulating certain transformation properties of field
functions. In Aristotelian terms, the covariance is a plain potentiality, but
not necessarily entelechy.",1605.05358v2
2019-09-04,Probing Lorentz Invariance With Top Pair Production at the LHC and Future Colliders,"This article presents prospects for Lorentz-violation searches with
$t\bar{t}$ at the LHC and future colliders. After a short presentation of the
Standard-Model Extension as a Lorentz-symmetry-breaking effective field theory,
we will focus on $t\bar{t}$ production. We study the impact of Lorentz
violation as a function of center-of-mass energy and evaluate the sensitivity
of collider experiments to this signal.",1909.01990v1
2019-10-22,Modifications to Plane Gravitational Waves from Minimal Lorentz Violation,"General Relativity predicts two modes for plane gravitational waves. When a
tiny violation of Lorentz invariance occurs, the two gravitational wave modes
are modified. We use perturbation theory to study the detailed form of the
modifications to the two gravitational wave modes from the minimal
Lorentz-violation coupling. The perturbation solution for the metric
fluctuation up to the first order in Lorentz violation is discussed. Then, we
investigate the motions of test particles under the influence of the plane
gravitational waves with Lorentz violation. First-order deviations from the
usual motions are found.",1910.09762v1
2019-08-02,Topics in Lorentz Geometry,"Lecture notes from the mini-course ""Topics in Lorentz Geometry"" taught at the
University of S\~{a}o Paulo, in March/2019. The text has three parts: (i) an
overall view of linear algebra in the pseudo-Euclidean space
$\mathbb{R}^n_\nu$, with focus on Lorentz-Minkowski space and its role in
Physics; (ii) a version of the Fundamental Theorem of Curves in 3-dimensional
Lorentz-Minkowski space, with adaptations to curves with degenerate osculating
plane; (iii) the problem of the diagonalization of the Weingarten map for
timelike surfaces, local classification of surfaces with constant Gaussian
curvature $K$ and Weierstrass' representation formula in Lorentz-Minkowski
space (using split-complex algebra). V2: added references.",1908.01710v2
2021-09-15,Penning-Trap Searches for Lorentz and CPT Violation,"An overview of recent progress on testing Lorentz and CPT symmetry using
Penning traps is presented. The theory of quantum electrodynamics with
Lorentz-violating operators of mass dimensions up to six is summarized.
Dominant shifts in the cyclotron and anomaly frequencies of the confined
particles and antiparticles due to Lorentz and CPT violation are derived.
Existing results of the comparisons of charge-to-mass ratios and magnetic
moments involving protons, antiprotons, electrons, and positrons are used to
constrain various coefficients for Lorentz violation.",2109.07597v1
2021-11-24,Quantum corrections to the Lorentz algebra due to mixed gravitational-$U(1)$-chiral anomalies,"We calculate the quantum corrections to the Lorentz algebra for chiral Weyl
fermions interacting with an external $U(1)$ gauge field in a background
Riemann-Cartan (RC) spacetime. This was achieved by setting up the equal-time
commutation relations (ETCR) for the canonical spin current of chiral Weyl
fermions. Furthermore, these quantum corrections lead to an order sensitive
commutator, i.e., swapping the Lorentz generators in the commutator doesn't
merely lead to a sign change, but rather a completely different correction term
to the Lorentz algebra. Thus, the algebra of Lorentz is altered due to
anomalies associated with chiral particles.",2111.12418v1
2022-06-22,Lorentz symmetry breaking and supersymmetry,"We discuss three manners to implement Lorentz symmetry breaking in a
superfield theory formulated within the superfield formalism, that is,
deformation of the supersymmetry algebra, introducing of an extra superfield
whose components can depend on Lorentz-violating (LV) vectors (tensors), and
adding of new terms proportional to LV vectors (tensors) to the superfield
action. We illustrate these methodologies with examples of quantum
calculations.",2206.11002v2
2023-01-30,Measuring Lorentz Violation in Weak Gravity Fields,"Many new linearized coefficients for Lorentz violation are discovered in our
recent work on the construction of a generic Lorentz-violating effective field
theory in curved spacetime. The new coefficients can be constrained by
experiments in weak gravity fields. In this work, we compare experiments in
different gravitational potentials and study three types of gravity-related
experiments: free-fall, gravitational interferometer, and gravitational
bound-state experiments. First constraints on the new coefficients for Lorentz
violation are extracted from those experiments.",2301.12705v1
2023-04-20,Violation of the Landau-Yang theorem from Infrared Lorentz Symmetry Breaking,"Lorentz symmetry forbids decays of massive spin-1 particle like the $Z^0$
into two massless photons, a result known as the Landau-Yang theorem. But it is
known that infrared effects can break Lorentz invariance. Employing the
construction of Mund et. al. \cite{MRS} which incorporated this Lorentz
violation, we propose an interaction leading to the decay $Z^0 \rightarrow 2
\gamma$ and study the dependence of the decay on the parameter of this Lorentz
violation.",2304.11008v2
2023-07-12,Lorentz-covariant spinor wave packet,"We propose a new formulation of manifestly Lorentz-covariant spinor
wave-packet basis. The conventional definition of the spinor wave packet is
problematic in the sense that it suffers from mixing with other wave packets
under Lorentz transformations. Our formulation evades this difficulty of
mixing. This wave packet forms a complete set that can expand a free spinor
field in a Lorentz covariant manner. In addition, we present a
Lorentz-invariant expression of zero-point energy.",2307.05932v2
2024-03-15,"The self-dual Lorentz violating model: quantization, scattering and dual equivalence","In this paper, we analysis the dynamics, at the quantum level, of the
self-dual field minimally coupled to bosons with Lorentz symmetry breaking. We
quantize the model by applying the Dirac bracket canonical quantization
procedure. In addition, we test the relativistic invariance of the model by
computing the boson-boson elastic scattering amplitude. Therefore, we show that
the Lorentz symmetry breaking has been restored at the quantum level. We
finalize our analysis by computing the dual equivalence between the self-dual
model with Lorentz symmetry breaking coupled with bosonic matter and the
Maxwell-Chern-Simons with Lorentz invariance violation coupled with bosonic
field.",2403.10224v1
1999-11-24,Damped Lyman alpha absorber and the faint end of the galaxy luminosity function at high redshift,"We combine predictions for several hierarchical cosmogonies with
observational evidence on damped Lyman alpha systems to establish a
correspondence between the high redshift galaxy population and the properties
of damped Lyman alpha systems. We assume that high redshift galaxies and damped
Lyman alpha systems are hosted by the same dark matter halos and require
consistency between the predicted halo space density, the rate of incidence and
the velocity width distribution of damped Lyman alpha systems, and the observed
galaxy luminosity function at the bright end. We arrive at the following
results: (1) predicted impact parameters between the damped absorption system
and the luminous part of the absorbing galaxy are expected to be very small
(0.3 - 1arcsec) for most galaxies; (2) luminosities of galaxies causing damped
absorption are generally fainter than m_R = 25 and damped Lyman alpha systems
are predicted to sample preferentially the outer regions of galaxies at the
faint end of the galaxy luminosity function at high redshift. Therefore, DLAS
should currently provide the best probe of the progenitors of normal
present-day galaxies.",9911447v1
2003-03-13,An explicit unconditionally stable numerical method for solving damped nonlinear Schrödinger equations with a focusing nonlinearity,"This paper introduces an extension of the time-splitting sine-spectral (TSSP)
method for solving damped focusing nonlinear Schr\""{o}dinger equations (NLS).
The method is explicit, unconditionally stable and time transversal invariant.
Moreover, it preserves the exact decay rate for the normalization of the wave
function if linear damping terms are added to the NLS. Extensive numerical
tests are presented for cubic focusing nonlinear Schr\""{o}dinger equations in
2d with a linear, cubic or a quintic damping term. Our numerical results show
that quintic or cubic damping always arrests blowup, while linear damping can
arrest blowup only when the damping parameter $\dt$ is larger than a threshold
value $\dt_{\rm th}$. We note that our method can also be applied to solve the
3d Gross-Pitaevskii equation with a quintic damping term to model the dynamics
of a collapsing and exploding Bose-Einstein condensate (BEC).",0303158v1
2004-11-03,Quantum probability applied to the damped harmonic oscillator,"In this introductory course we sketch the framework of quantum probability in
order to discuss open quantum systems, in particular the damped harmonic
oscillator.",0411024v1
2006-11-23,Path integrals and wavepacket evolution for damped mechanical systems,"Damped mechanical systems with various forms of damping are quantized using
the path integral formalism. In particular, we obtain the path integral kernel
for the linearly damped harmonic oscillator and a particle in a uniform
gravitational field with linearly or quadratically damped motion. In each case,
we study the evolution of Gaussian wavepackets and discuss the characteristic
features that help us distinguish between different types of damping. For
quadratic damping, we show that the action and equation of motion of such a
system has a connection with the zero dimensional version of a currently
popular scalar field theory. Furthermore we demonstrate that the equation of
motion (for quadratic damping) can be identified as a geodesic equation in a
fictitious two-dimensional space.",0611239v1
2007-07-05,Damping of bulk excitations over an elongated BEC - the role of radial modes,"We report the measurement of Beliaev damping of bulk excitations in cigar
shaped Bose Einstein condensates of atomic vapor. By using post selection,
excitation line shapes of the total population are compared with those of the
undamped excitations. We find that the damping depends on the initial
excitation energy of the decaying quasi particle, as well as on the excitation
momentum. We model the condensate as an infinite cylinder and calculate the
damping rates of the different radial modes. The derived damping rates are in
good agreement with the experimentally measured ones. The damping rates
strongly depend on the destructive interference between pathways for damping,
due to the quantum many-body nature of both excitation and damping products.",0707.0776v1
2008-09-22,Damping in 2D and 3D dilute Bose gases,"Damping in 2D and 3D dilute gases is investigated using both the
hydrodynamical approach and the Hartree-Fock-Bogoliubov (HFB) approximation .
We found that the both methods are good for the Beliaev damping at zero
temperature and Landau damping at very low temperature, however, at high
temperature, the hydrodynamical approach overestimates the Landau damping and
the HFB gives a better approximation. This result shows that the comparison of
the theoretical calculation using the hydrodynamical approach and the
experimental data for high temperature done by Vincent Liu (PRL {\bf21} 4056
(1997)) is not proper. For two-dimensional systems, we show that the Beliaev
damping rate is proportional to $k^3$ and the Landau damping rate is
proportional to $ T^2$ for low temperature and to $T$ for high temperature. We
also show that in two dimensions the hydrodynamical approach gives the same
result for zero temperature and for low temperature as HFB, but overestimates
the Landau damping for high temperature.",0809.3632v3
2008-12-08,Landau Damping and Alfven Eigenmodes of Neutron Star Torsion Oscillations,"Torsion oscillations of the neutron star crust are Landau damped by the
Alfven continuum in the bulk. For strong magnetic fields (in magnetars),
undamped Alfven eigenmodes appear.",0812.1570v1
2010-09-24,Spatial Damping of Propagating Kink Waves in Prominence Threads,"Transverse oscillations and propagating waves are frequently observed in
threads of solar prominences/filaments and have been interpreted as kink
magnetohydrodynamic (MHD) modes. We investigate the spatial damping of
propagating kink MHD waves in transversely nonuniform and partially ionized
prominence threads. Resonant absorption and ion-neutral collisions (Cowling's
diffusion) are the damping mechanisms taken into account. The dispersion
relation of resonant kink waves in a partially ionized magnetic flux tube is
numerically solved by considering prominence conditions. Analytical expressions
of the wavelength and damping length as functions of the kink mode frequency
are obtained in the Thin Tube and Thin Boundary approximations. For typically
reported periods of thread oscillations, resonant absorption is an efficient
mechanism for the kink mode spatial damping, while ion-neutral collisions have
a minor role. Cowling's diffusion dominates both the propagation and damping
for periods much shorter than those observed. Resonant absorption may explain
the observed spatial damping of kink waves in prominence threads. The
transverse inhomogeneity length scale of the threads can be estimated by
comparing the observed wavelengths and damping lengths with the theoretically
predicted values. However, the ignorance of the form of the density profile in
the transversely nonuniform layer introduces inaccuracies in the determination
of the inhomogeneity length scale.",1009.4871v1
2012-08-01,Artificial Neural Network Based Prediction of Optimal Pseudo-Damping and Meta-Damping in Oscillatory Fractional Order Dynamical Systems,"This paper investigates typical behaviors like damped oscillations in
fractional order (FO) dynamical systems. Such response occurs due to the
presence of, what is conceived as, pseudo-damping and meta-damping in some
special class of FO systems. Here, approximation of such damped oscillation in
FO systems with the conventional notion of integer order damping and time
constant has been carried out using Genetic Algorithm (GA). Next, a multilayer
feed-forward Artificial Neural Network (ANN) has been trained using the GA
based results to predict the optimal pseudo and meta-damping from knowledge of
the maximum order or number of terms in the FO dynamical system.",1208.0318v1
2012-08-27,Optimization of the damped quantum search,"The damped quantum search proposed in [A. Mizel, Phys. Rev. Lett., 102 150501
(2009)] was analyzed by calculating the highest possible probability of finding
the target state in each iteration. A new damping parameter that depends on the
number of iterations was obtained, this was compared to the critical damping
parameter for different values of target to database size ratio. The result
shows that the range of the new damping parameter as a function of the target
to database size ratio increases as the number of iterations is increased.
Furthermore, application of the new damping parameter per iteration on the
damped quantum search scheme shows a significant improvement on some target to
database size ratio (i.e. greater than or equal to 50% maximum percentage
difference) over the critically damped quantum search.",1208.5475v1
2013-04-03,Damping the zero-point energy of a harmonic oscillator,"The physics of quantum electromagnetism in an absorbing medium is that of a
field of damped harmonic oscillators. Yet until recently the damped harmonic
oscillator was not treated with the same kind of formalism used to describe
quantum electrodynamics in a arbitrary medium. Here we use the techniques of
macroscopic QED, based on the Huttner--Barnett reservoir, to describe the
quantum mechanics of a damped oscillator. We calculate the thermal and
zero-point energy of the oscillator for a range of damping values from zero to
infinity. While both the thermal and zero-point energies decrease with damping,
the energy stored in the oscillator at fixed temperature increases with
damping, an effect that may be experimentally observable. As the results follow
from canonical quantization, the uncertainty principle is valid for all damping
levels.",1304.0977v2
2015-05-28,Damping factors for head-tail modes at strong space charge,"This paper suggests how feedback and Landau damping can be taken into account
for transverse oscillations of bunched beam at strong space charge.",1505.07704v1
2015-06-18,Damping of MHD turbulence in partially ionized plasma: implications for cosmic ray propagation,"We study the damping from neutral-ion collisions of both incompressible and
compressible magnetohydrodynamic (MHD) turbulence in partially ionized medium.
We start from the linear analysis of MHD waves applying both single-fluid and
two-fluid treatments. The damping rates derived from the linear analysis are
then used in determining the damping scales of MHD turbulence. The physical
connection between the damping scale of MHD turbulence and cutoff boundary of
linear MHD waves is investigated. Our analytical results are shown to be
applicable in a variety of partially ionized interstellar medium (ISM) phases
and solar chromosphere. As a significant astrophysical utility, we introduce
damping effects to propagation of cosmic rays in partially ionized ISM. The
important role of turbulence damping in both transit-time damping and
gyroresonance is identified.",1506.05585v1
2016-02-04,Damping Evaluation for Free Vibration of Spherical Structures in Elastodynamic-Acoustic Interaction,"This paper discusses the free vibration of elastic spherical structures in
the presence of an externally unbounded acoustic medium. In this vibration,
damping associated with the radiation of energy from the confined solid medium
to the surrounding acoustic medium is observed. Evaluating the coupled system
response (solid displacement and acoustic pressure) and characterizing the
acoustic radiation damping in conjunction with the media properties are the
main objectives of this research. In this work, acoustic damping is
demonstrated for two problems: the thin spherical shell and the solid sphere.
The mathematical approach followed in solving these coupled problems is based
on the Laplace transform method. The linear under-damped harmonic oscillator is
the reference model for damping estimation. The damping evaluation is performed
in frequency as well as in time domains; both investigations lead to identical
damping factor expressions.",1604.06738v1
2018-11-01,Hereditary effects of exponentially damped oscillators with past histories,"Hereditary effects of exponentially damped oscillators with past histories
are considered in this paper. Nonviscously damped oscillators involve
hereditary damping forces which depend on time-histories of vibrating motions
via convolution integrals over exponentially decaying functions. As a result,
this kind of oscillators are said to have memory. In this work, initialization
for nonviscously damped oscillators is firstly proposed. Unlike the classical
viscously damped ones, information of the past history of response velocity is
necessary to fully determine the dynamic behaviors of nonviscously damped
oscillators. Then, initialization response of exponentially damped oscillators
is obtained to characterize the hereditary effects on the dynamic response. At
last, stability of initialization response is proved and the hereditary effects
are shown to gradually recede with increasing of time.",1811.00216v1
2017-01-10,Magnetic properties in ultra-thin 3d transition metal alloys II: Experimental verification of quantitative theories of damping and spin-pumping,"A systematic experimental study of Gilbert damping is performed via
ferromagnetic resonance for the disordered crystalline binary 3d transition
metal alloys Ni-Co, Ni-Fe and Co-Fe over the full range of alloy compositions.
After accounting for inhomogeneous linewidth broadening, the damping shows
clear evidence of both interfacial damping enhancement (by spin pumping) and
radiative damping. We quantify these two extrinsic contributions and thereby
determine the intrinsic damping. The comparison of the intrinsic damping to
multiple theoretical calculations yields good qualitative and quantitative
agreement in most cases. Furthermore, the values of the damping obtained in
this study are in good agreement with a wide range of published experimental
and theoretical values. Additionally, we find a compositional dependence of the
spin mixing conductance.",1701.02475v1
2018-05-21,Critical damping in nonviscously damped linear systems,"In structural dynamics, energy dissipative mechanisms with non-viscous
damping are characterized by their dependence on the time-history of the
response velocity, mathematically represented by convolution integrals
involving hereditary functions. Combination of damping parameters in the
dissipative model can lead the system to be overdamped in some (or all) modes.
In the domain of the damping parameters, the thresholds between induced
oscillatory and non--oscillatory motion are called critical damping surfaces
(or manifolds, since we can have a lot of parameters). In this paper a general
method to obtain critical damping surfaces for nonviscously damped systems is
proposed. The approach is based on transforming the algebraic equations which
defined implicitly the critical curves into a system of differential equations.
The derivations are validated with three numerical methods covering single and
multiple degree of freedom systems.",1805.08022v1
2017-06-14,Temperature-dependent Gilbert damping of Co2FeAl thin films with different degree of atomic order,"Half-metallicity and low magnetic damping are perpetually sought for in
spintronics materials and full Heusler alloys in this respect provide
outstanding properties. However, it is challenging to obtain the well-ordered
half-metallic phase in as-deposited full Heusler alloys thin films and theory
has struggled to establish a fundamentals understanding of the temperature
dependent Gilbert damping in these systems. Here we present a study of the
temperature dependent Gilbert damping of differently ordered as-deposited
Co2FeAl full Heusler alloy thin films. The sum of inter- and intraband electron
scattering in conjunction with the finite electron lifetime in Bloch states
govern the Gilbert damping for the well-ordered phase in contrast to the
damping of partially-ordered and disordered phases which is governed by
interband electronic scattering alone. These results, especially the ultralow
room temperature intrinsic damping observed for the well-ordered phase provide
new fundamental insights to the physical origin of the Gilbert damping in full
Heusler alloy thin films.",1706.04670v2
2019-07-01,Magnon decay theory of Gilbert damping in metallic antiferromagnets,"Gilbert damping is a key property governing magnetization dynamics in ordered
magnets. We present a theoretical study of intrinsic Gilbert damping induced by
magnon decay in antiferromagnetic metals through $s$-$d$ exchange interaction.
Our theory delineates the qualitative features of damping in metallic
antiferromagnets owing to their bipartite nature, in addition to providing
analytic expressions for the damping parameters. Magnon-induced intraband
electron scattering is found to predominantly cause magnetization damping,
whereas the N\'eel field is found to be damped via disorder. Depending on the
conduction electron band structure, we predict that magnon-induced interband
electron scattering around band crossings may be exploited to engineer a strong
N\'eel field damping.",1907.01045v1
2019-10-14,Decay rates for the damped wave equation with finite regularity damping,"Decay rates for the energy of solutions of the damped wave equation on the
torus are studied. In particular, damping invariant in one direction and equal
to a sum of squares of nonnegative functions with a particular number of
derivatives of regularity is considered. For such damping energy decays at rate
$1/t^{2/3}$. If additional regularity is assumed the decay rate improves. When
such a damping is smooth the energy decays at $1/t^{4/5-\delta}$. The proof
uses a positive commutator argument and relies on a pseudodifferential calculus
for low regularity symbols.",1910.06372v3
2017-09-05,Enhancement of space-charge induced damping due to reactive impedances for head-tail modes,"Landau damping of head-tail modes in bunches due to spreads in the tune shift
can be a deciding factor for beam stability. We demonstrate that the coherent
tune shifts due to reactive impedances can enhance the space-charge induced
damping and change the stability thresholds (here, a reactive impedance implies
the imaginary part of the impedance of both signs). For example, high damping
rates at strong space-charge, or damping of the $k=0$ mode, can be possible. It
is shown and explained, how the negative reactive impedances (causing negative
coherent tune shifts similarly to the effect of space-charge) can enhance the
Landau damping, while the positive coherent tune shifts have an opposite
effect. It is shown that the damping rate is a function of the coherent mode
position in the incoherent spectrum, in accordance with the concept of the
interaction of a collective mode with resonant particles. We present an
analytical model, which allows for quantitative predictions of damping
thresholds for different head-tail modes, for arbitrary space-charge and
coherent tune-shift conditions, as it is verified using particle tracking
simulations.",1709.01425v1
2019-02-22,Strongly Enhanced Gilbert Damping in 3d Transition Metal Ferromagnet Monolayers in Contact with Topological Insulator Bi2Se3,"Engineering Gilbert damping of ferromagnetic metal films is of great
importance to exploit and design spintronic devices that are operated with an
ultrahigh speed. Based on scattering theory of Gilbert damping, we extend the
torque method originally used in studies of magnetocrystalline anisotropy to
theoretically determine Gilbert dampings of ferromagnetic metals. This method
is utilized to investigate Gilbert dampings of 3d transition metal ferromagnet
iron, cobalt and nickel monolayers that are contacted by the prototypical
topological insulator Bi2Se3. Amazingly, we find that their Gilbert dampings
are strongly enhanced by about one order in magnitude, compared with dampings
of their bulks and free-standing monolayers, owing to the strong spin-orbit
coupling of Bi2Se3. Our work provides an attractive route to tailoring Gilbert
damping of ferromagnetic metallic films by putting them in contact with
topological insulators.",1902.08700v1
2019-08-01,The Temperature-dependent Damping of Propagating Slow Magnetoacoustic Waves,"The rapid damping of slow magnetoacoustic waves in the solar corona has been
extensively studied in previous years. Most studies suggest that thermal
conduction is a dominant contributor to this damping, albeit with a few
exceptions. Employing extreme-ultraviolet (EUV) imaging data from SDO/AIA, we
measure the damping lengths of propagating slow magnetoacoustic waves observed
in several fan-like loop structures using two independent methods. The
dependence of the damping length on temperature has been studied for the first
time. The results do not indicate any apparent decrease in damping length with
temperature, which is in contrast to the existing viewpoint. Comparing with the
corresponding theoretical values calculated from damping due to thermal
conduction, it is inferred that thermal conduction is suppressed in hotter
loops. An alternative interpretation that suggests thermal conduction is not
the dominant damping mechanism, even for short period waves in warm active
region loops, is also presented.",1908.00384v1
2022-07-01,Seismic Response of Yielding Structures Coupled to Rocking Walls with Supplemental Damping,"Given that the coupling of a framing structure to a strong, rocking wall
enforces a first-mode response, this paper investigates the dynamic response of
a yielding single-degree-of-freedom oscillator coupled to a rocking wall with
supplemental damping (hysteretic or linear viscous) along its sides. The full
nonlinear equations of motion are derived, and the study presents an earthquake
response analysis in term of inelastic spectra. The study shows that for
structures with preyielding period T1<1.0 s the effect of supplemental damping
along the sides of the rocking wall is marginal even when large values of
damping are used. The study uncovers that occasionally the damped response
matches or exceeds the undamped response; however, when this happens, the
exceedance is marginal. The paper concludes that for yielding structures with
strength less than 10% of their weight the use of supplemental damping along
the sides of a rocking wall coupled to a yielding structure is not recommended.
The paper shows that supplemental damping along the sides of the rocking wall
may have some limited beneficial effects for structures with longer preyielding
periods (say T1>1.0 s). Nevertheless, no notable further response reduction is
observed when larger values of hysteretic or viscous damping are used.",2207.00641v1
2022-11-24,Influence of non-local damping on magnon properties of ferromagnets,"We study the influence of non-local damping on magnon properties of Fe, Co,
Ni and Fe$_{1-x}$Co$_{x}$ ($x=30\%,50\%$) alloys. The Gilbert damping parameter
is typically considered as a local scalar both in experiment and in theoretical
modelling. However, recent works have revealed that Gilbert damping is a
non-local quantity that allows for energy dissipation between atomic sites.
With the Gilbert damping parameters calculated from a state-of-the-art
real-space electronic structure method, magnon lifetimes are evaluated from
spin dynamics and linear response, where a good agreement is found between
these two methods. It is found that non-local damping affects the magnon
lifetimes in different ways depending on the system. Specifically, we find that
in Fe, Co, and Ni the non-local damping decreases the magnon lifetimes, while
in $\rm Fe_{70}Co_{30}$ and Fe$_{50}$Co$_{50}$ an opposite, non-local damping
effect is observed, and our data show that it is much stronger in the former.",2211.13486v1
2023-03-08,Material-Geometry Interplay in Damping of Biomimetic Scale Beams,"Biomimetic scale-covered substrates are architected meta-structures
exhibiting fascinating emergent nonlinearities via the geometry of collective
scales contacts. In spite of much progress in understanding their elastic
nonlinearity, their dissipative behavior arising from scales sliding is
relatively uninvestigated in the dynamic regime. Recently discovered is the
phenomena of viscous emergence, where dry Coulomb friction between scales can
lead to apparent viscous damping behavior of the overall multi-material
substrate. In contrast to this structural dissipation, material dissipation
common in many polymers has never been considered, especially synergestically
with geometrical factors. This is addressed here for the first time, where
material visco-elasticity is introduced via a simple Kelvin-Voigt model for
brevity and clarity. The results contrast the two damping sources in these
architectured systems: material viscoelasticity, and geometrical frictional
scales contact. It is discovered that although topically similar in effective
damping, viscoelsatic damping follows a different damping envelope than dry
friction, including starkly different effects on damping symmetry and specific
damping capacity.",2303.04920v1
2020-07-28,Complete complementarity relations and its Lorentz invariance,"It is well known that entanglement under Lorentz boosts is highly dependent
on the boost scenario in question. For single particle states, a spin-momentum
product state can be transformed into an entangled state. However, entanglement
is just one of the aspects that completely characterizes a quantum system. The
other two are known as the wave-particle duality. Although the entanglement
entropy does not remain invariant under Lorentz boosts, and neither do the
measures of predictability and coherence, we show here that these three
measures taken together, in a complete complementarity relation (CCR), are
Lorentz invariant. Peres et al., in [Phys. Rev. Lett. 88, 230402 (2002)],
realized that even though it is possible to formally define spin in any Lorentz
frame, there is no relationship between the observable expectation values in
different Lorentz frames. Analogously, even though it is possible to formally
define complementarity in any Lorentz frame, in principle, there's no
relationship between the complementarity relations of different Lorentz frames.
However, our result shows that it's possible to connect complete
complementarity relations in different Lorentz frames. In addition, we explore
relativistic scenarios for single and two particle states, which helps in
understanding the exchange of different aspects of a quantum system under
Lorentz boosts.",2007.14480v5
1998-03-28,Landau damping and the echo effect in a confined Bose-Einstein condensate,"Low energy collective mode of a confined Bose-Einstein condensate should
demonstrate the echo effect in the regime of Landau damping. This echo is a
signature of reversible nature of Landau damping. General expression for the
echo profile is derived in the limit of small amplitudes of the external
pulses. Several universal features of the echo are found. The existence of echo
in other cases of reversible damping -- Fano effect and Caldeira-Leggett model
-- is emphasized. It is suggested to test reversible nature of the damping in
the atomic traps by conducting the echo experiment.",9803351v1
2000-07-10,Dephasing of Electrons on Helium by Collisions with Gas Atoms,"The damping of quantum effects in the transport properties of electrons
deposited on a surface of liquid helium is studied. It is found that due to
vertical motion of the helium vapour atoms the interference of paths of
duration $t$ is damped by a factor $\exp - (t/\tau_v)^3$. An expression is
derived for the weak-localization lineshape in the case that damping occurs by
a combination of processes with this type of cubic exponential damping and
processes with a simple exponential damping factor.",0007160v1
1997-10-07,Damping rate of plasmons and photons in a degenerate nonrelativistic plasma,"A calculation is presented of the plasmon and photon damping rates in a dense
nonrelativistic plasma at zero temperature, following the resummation program
of Braaten-Pisarski. At small soft momentum $k$, the damping is dominated by $3
\to 2$ scattering processes corresponding to double longitudinal Landau
damping. The dampings are proportional to $(\alpha/v_{F})^{3/2} k^2/m$, where
$v_{F}$ is the Fermi velocity.",9710260v1
2002-12-16,Influence of damping on the vanishing of the electro-optic effect in chiral isotropic media,"Using first principles, it is demonstrated that radiative damping alone
cannot lead to a nonvanishing electro-optic effect in a chiral isotropic
medium. This conclusion is in contrast with that obtained by a calculation in
which damping effects are included using the standard phenomenological model.
We show that these predictions differ because the phenomenological damping
equations are valid only in regions where the frequencies of the applied
electromagnetic fields are nearly resonant with the atomic transitions. We also
show that collisional damping can lead to a nonvanishing electrooptic effect,
but with a strength sufficiently weak that it is unlikely to be observable
under realistic laboratory conditions.",0212089v1
2005-08-28,Simultaneous amplitude and phase damping of a kind of Gaussian states and their separability,"We give out the time evolution solution of simultaneous amplitude and phase
damping for any continuous variable state. For the simultaneous amplitude and
phase damping of a wide class of two- mode entangled Gaussian states, two
analytical conditions of the separability are given. One is the sufficient
condition of separability. The other is the condition of PPT separability where
the Peres-Horodecki criterion is applied. Between the two conditions there may
exist bound entanglement. The simplest example is the simultaneous amplitude
and phase damping of a two-mode squeezed vacuum state. The damped state is
non-Gaussian.",0508209v2
2007-05-14,"Identification of the dominant precession damping mechanism in Fe, Co, and Ni by first-principles calculations","The Landau-Lifshitz equation reliably describes magnetization dynamics using
a phenomenological treatment of damping. This paper presents first-principles
calculations of the damping parameters for Fe, Co, and Ni that quantitatively
agree with existing ferromagnetic resonance measurements. This agreement
establishes the dominant damping mechanism for these systems and takes a
significant step toward predicting and tailoring the damping constants of new
materials.",0705.1990v1
2007-08-28,Ising Dynamics with Damping,"We show for the Ising model that is possible construct a discrete time
stochastic model analogous to the Langevin equation that incorporates an
arbitrary amount of damping. It is shown to give the correct equilibrium
statistics and is then used to investigate nonequilibrium phenomena, in
particular, magnetic avalanches. The value of damping can greatly alter the
shape of hysteresis loops, and for small damping and high disorder, the
morphology of large avalanches can be drastically effected. Small damping also
alters the size distribution of avalanches at criticality.",0708.3855v1
2008-02-08,On the scaling of the damping time for resonantly damped oscillations in coronal loops,"There is not as yet full agreement on the mechanism that causes the rapid
damping of the oscillations observed by TRACE in coronal loops. It has been
suggested that the variation of the observed values of the damping time as
function of the corresponding observed values of the period contains
information on the possible damping mechanism. The aim of this Letter is to
show that, for resonant absorption, this is definitely not the case unless
detailed a priori information on the individual loops is available.",0802.1143v1
2008-10-02,Critically damped quantum search,"Although measurement and unitary processes can accomplish any quantum
evolution in principle, thinking in terms of dissipation and damping can be
powerful. We propose a modification of Grover's algorithm in which the idea of
damping plays a natural role. Remarkably, we have found that there is a
critical damping value that divides between the quantum $O(\sqrt{N})$ and
classical O(N) search regimes. In addition, by allowing the damping to vary in
a fashion we describe, one obtains a fixed-point quantum search algorithm in
which ignorance of the number of targets increases the number of oracle queries
only by a factor of 1.5.",0810.0470v1
2009-07-01,Modal approximations to damped linear systems,"We consider a finite dimensional damped second order system and obtain
spectral inclusion theorems for the related quadratic eigenvalue problem. The
inclusion sets are the 'quasi Cassini ovals' which may greatly outperform
standard Gershgorin circles. As the unperturbed system we take a modally damped
part of the system; this includes the known proportionally damped models, but
may give much sharper estimates. These inclusions are then applied to derive
some easily calculable sufficient conditions for the overdampedness of a given
damped system.",0907.0167v1
2010-01-14,Multi-Error-Correcting Amplitude Damping Codes,"We construct new families of multi-error-correcting quantum codes for the
amplitude damping channel. Our key observation is that, with proper encoding,
two uses of the amplitude damping channel simulate a quantum erasure channel.
This allows us to use concatenated codes with quantum erasure-correcting codes
as outer codes for correcting multiple amplitude damping errors. Our new codes
are degenerate stabilizer codes and have parameters which are better than the
amplitude damping codes obtained by any previously known construction.",1001.2356v1
2011-09-05,Spectral theory of damped quantum chaotic systems,"We investigate the spectral distribution of the damped wave equation on a
compact Riemannian manifold, especially in the case of a metric of negative
curvature, for which the geodesic flow is Anosov. The main application is to
obtain conditions (in terms of the geodesic flow on $X$ and the damping
function) for which the energy of the waves decays exponentially fast, at least
for smooth enough initial data. We review various estimates for the high
frequency spectrum in terms of dynamically defined quantities, like the value
distribution of the time-averaged damping. We also present a new condition for
a spectral gap, depending on the set of minimally damped trajectories.",1109.0930v1
2012-06-07,From resolvent estimates to damped waves,"In this paper we show how to obtain decay estimates for the damped wave
equation on a compact manifold without geometric control via knowledge of the
dynamics near the un-damped set. We show that if replacing the damping term
with a higher-order \emph{complex absorbing potential} gives an operator
enjoying polynomial resolvent bounds on the real axis, then the ""resolvent""
associated to our damped problem enjoys bounds of the same order. It is known
that the necessary estimates with complex absorbing potential can also be
obtained via gluing from estimates for corresponding non-compact models.",1206.1565v1
2012-12-03,Inviscid limit of stochastic damped 2D Navier-Stokes equations,"We consider the inviscid limit of the stochastic damped 2D Navier- Stokes
equations. We prove that, when the viscosity vanishes, the stationary solution
of the stochastic damped Navier-Stokes equations converges to a stationary
solution of the stochastic damped Euler equation and that the rate of
dissipation of enstrophy converges to zero. In particular, this limit obeys an
enstrophy balance. The rates are computed with respect to a limit measure of
the unique invariant measure of the stochastic damped Navier-Stokes equations.",1212.0509v3
2014-01-13,NLSE for quantum plasmas with the radiation damping,"We consider contribution of the radiation damping in the quantum hydrodynamic
equations for spinless particles. We discuss possibility of obtaining of
corresponding non-linear Schrodinger equation (NLSE) for the macroscopic wave
function. We compare contribution of the radiation damping with weakly (or
semi-) relativistic effects appearing in the second order by v/c. The radiation
damping appears in the third order by v/c. So it might be smaller than weakly
relativistic effects, but it gives damping of the Langmuir waves which can be
considerable.",1401.2829v1
2014-09-26,An ultimate storage ring lattice with vertical emittance generated by damping wigglers,"We discuss the approach of generating round beams for ultimate storage rings
using vertical damping wigglers (with horizontal magnetic field). The vertical
damping wigglers provide damping and excite vertical emittance. This eliminates
the need to generate large linear coupling that is impractical with traditional
off-axis injection. We use a PEP-X compatible lattice to demonstrate the
approach. This lattice uses separate quadrupole and sextupole magnets with
realistic gradient strengths. Intrabeam scattering effects are calculated. The
horizontal and vertical emittances are 22.3 pm and 10.3 pm, respectively, for a
200 mA, 4.5 GeV beam, with a vertical damping wiggler of a total length of 90
meters, peak field of 1.5 T and wiggler period of 100 mm.",1409.7452v2
2017-03-01,Behaviors of the energy of solutions of two coupled wave equations with nonlinear damping on a compact manifold with boundary,"In this paper we study the behaviors of the the energy of solutions of
coupled wave equations on a compact manifold with boundary in the case of
indirect nonlinear damping . Only one of the two equations is directly damped
by a localized nonlinear damping term. Under geometric conditions on both the
coupling and the damping regions we prove that the rate of decay of the energy
of smooth solutions of the system is determined from a first order differential
equation .",1703.00172v1
2018-02-28,Nonexistence of global solutions of wave equations with weak time-dependent damping and combined nonlinearity,"In our previous two works, we studied the blow-up and lifespan estimates for
damped wave equations with a power nonlinearity of the solution or its
derivative, with scattering damping independently. In this work, we are devoted
to establishing a similar result for a combined nonlinearity. Comparing to the
result of wave equation without damping, one can say that the scattering
damping has no influence.",1802.10273v1
2018-11-12,Choking non-local magnetic damping in exchange biased ferromagnets,"We investigated the temperature dependence of the magnetic damping in the
exchange biased Pt/ Fe50Mn50 /Fe20Ni80 /SiOx multilayers. In samples having a
strong exchange bias, we observed a drastic decrease of the magnetic damping of
the FeNi with increasing temperature up to the blocking temperature. The
results essentially indicate that the non-local enhancement of the magnetic
damping can be choked by the adjacent antiferromagnet and its temperature
dependent exchange bias. We also pointed out that such a strong temperature
dependent damping may be very beneficial for spintronic applications.",1811.04821v1
2019-05-23,Escaping Locally Optimal Decentralized Control Polices via Damping,"We study the evolution of locally optimal decentralized controllers with the
damping of the control system. Empirically it is shown that even for instances
with an exponential number of connected components, damping merges all local
solutions to the one global solution. We characterize the evolution of locally
optimal solutions with the notion of hemi-continuity and further derive
asymptotic properties of the objective function and of the locally optimal
controllers as the damping becomes large. Especially, we prove that with enough
damping, there is no spurious locally optimal controller with favorable control
structures. The convoluted behavior of the locally optimal trajectory is
illustrated with numerical examples.",1905.09915v1
2020-07-25,Decay for the Kelvin-Voigt damped wave equation: Piecewise smooth damping,"We study the energy decay rate of the Kelvin-Voigt damped wave equation with
piecewise smooth damping on the multi-dimensional domain. Under suitable
geometric assumptions on the support of the damping, we obtain the optimal
polynomial decay rate which turns out to be different from the one-dimensional
case studied in \cite{LR05}. This optimal decay rate is saturated by high
energy quasi-modes localised on geometric optics rays which hit the interface
along non orthogonal neither tangential directions. The proof uses
semi-classical analysis of boundary value problems.",2007.12994v2
2016-08-14,Mechanical energy and mean equivalent viscous damping for SDOF fractional oscillators,"This paper addresses the total mechanical energy of a single degree of
freedom fractional oscillator. Based on the energy storage and dissipation
properties of the Caputo fractional derivatives, the expression for total
mechanical energy in the single degree of freedom fractional oscillator is
firstly presented. The energy regeneration due to the external exciting force
and the energy loss due to the fractional damping force during the vibratory
motion are analyzed. Furthermore, based on the mean energy dissipation of the
fractional damping element in steady-state vibration, a new concept of mean
equivalent viscous damping is suggested and the value of the damping
coefficient is evaluated.",1608.04071v1
2017-06-02,Vanishing viscosity limit for global attractors for the damped Navier--Stokes system with stress free boundary conditions,"We consider the damped and driven Navier--Stokes system with stress free
boundary conditions and the damped Euler system in a bounded domain
$\Omega\subset\mathbf{R}^2$. We show that the damped Euler system has a
(strong) global attractor in~$H^1(\Omega)$. We also show that in the vanishing
viscosity limit the global attractors of the Navier--Stokes system converge in
the non-symmetric Hausdorff distance in $H^1(\Omega)$ to the the strong global
attractor of the limiting damped Euler system (whose solutions are not
necessarily unique).",1706.00607v1
2018-01-20,Long time dynamics for weakly damped nonlinear Klein-Gordon equations,"We continue our study of damped nonlinear Klein-Gordon equations. In our
previous work we considered fixed positive damping and proved a form of the
soliton resolution conjecture for radial solutions. In contrast, here we
consider damping which decreases in time to 0. In the class of radial data we
again establish soliton resolution provided the damping goes to 0 sufficiently
slowly. While our previous work relied on invariant manifold theory, here we
use the Lojasiewicz-Simon inequality applied to a suitable Lyapunov functional.",1801.06735v1
2019-09-18,Global smooth solutions of the damped Boussinesq equations with a class of large initial data,"The global regularity problem concerning the inviscid Boussinesq equations
remains an open problem. In an attempt to understand this problem, we examine
the damped Boussinesq equations and study how damping affects the regularity of
solutions. In this paper, we consider the global existence to the damped
Boussinesq equations with a class of large initial data, whose $B^{s}_{p,r}$ or
$\dot{B}^{s}_{p,r}$ norms can be arbitrarily large. The idea is splitting the
linear Boussinesq equations from the damped Boussinesq equations, the
exponentially decaying solution of the former equations together with the
structure of the Boussinesq equations help us to obtain the global smooth
solutions.",1909.08360v1
2020-02-15,Asymptotic profile and optimal decay of solutions of some wave equations with logarithmic damping,"We introduce a new model of the nonlocal wave equations with a logarithmic
damping mechanism. We consider the Cauchy poroblem for the new model in the
whole space. We study the asymptotic profile and optimal decay and blowup rates
of solutions as time goes to infinity. The damping terms considered in this
paper is not studied so far, and in the low frequency parameters the damping is
rather weakly effective than that of well-studied fractional type of nonlocal
damping. In order to get the optimal estimates in time we meet the so-called
hypergeometric functions with special parameters.",2002.06319v1
2019-08-22,Some remarks on the asymptotic profile of solutions to structurally damped $σ$-evolution equations,"In this paper, we are interested in analyzing the asymptotic profiles of
solutions to the Cauchy problem for linear structurally damped
$\sigma$-evolution equations in $L^2$-sense. Depending on the parameters
$\sigma$ and $\delta$ we would like to not only indicate approximation formula
of solutions but also recognize the optimality of their decay rates as well in
the distinct cases of parabolic like damping and $\sigma$-evolution like
damping. Moreover, such results are also discussed when we mix these two kinds
of damping terms in a $\sigma$-evolution equation to investigate how each of
them affects the asymptotic profile of solutions.",1908.08492v1
2020-05-13,Weak Input to state estimates for 2D damped wave equations with localized and non-linear damping,"In this paper, we study input-to-state (ISS) issues for damped wave equations
with Dirichlet boundary conditions on a bounded domain of dimension two. The
damping term is assumed to be non-linear and localized to an open subset of the
domain. In a first step, we handle the undisturbed case as an extension of a
previous work, where stability results are given with a damping term active on
the full domain. Then, we address the case with disturbances and provide
input-to-state types of results.",2005.06206v3
2020-08-12,From Lieb-Thirring inequalities to spectral enclosures for the damped wave equation,"Using a correspondence between the spectrum of the damped wave equation and
non-self-adjoint Schroedinger operators, we derive various bounds on complex
eigenvalues of the former. In particular, we establish a sharp result that the
one-dimensional damped wave operator is similar to the undamped one provided
that the L^1 norm of the (possibly complex-valued) damping is less than 2. It
follows that these small dampings are spectrally undetectable.",2008.05176v1
2021-08-02,Wide-Area Damping Control for Interarea Oscillations in Power Grids Based on PMU Measurements,"In this paper, a phasor measurement unit (PMU)-based wide-area damping
control method is proposed to damp the interarea oscillations that threaten the
modern power system stability and security. Utilizing the synchronized PMU
data, the proposed almost model-free approach can achieve an effective damping
for the selected modes using a minimum number of synchronous generators.
Simulations are performed to show the validity of the proposed wide-area
damping control scheme.",2108.01193v1
2021-09-05,Regularity of the semigroups associated with some damped coupled elastic systems II: a nondegenerate fractional damping case,"In this paper, we examine regularity issues for two damped abstract elastic
systems; the damping and coupling involve fractional powers $\mu, \theta$, with
$0 \leq \mu , \theta \leq 1$, of the principal operators. The matrix defining
the coupling and damping is nondegenerate. This new work is a sequel to the
degenerate case that we discussed recently in \cite{kfl}. First, we prove that
for $1/2 \leq \mu , \theta \leq 1$, the underlying semigroup is analytic. Next,
we show that for $\min(\mu,\theta) \in (0,1/2)$, the semigroup is of certain
Gevrey classes. Finally, some examples of application are provided.",2109.02044v1
2021-09-28,A robust and efficient line search for self-consistent field iterations,"We propose a novel adaptive damping algorithm for the self-consistent field
(SCF) iterations of Kohn-Sham density-functional theory, using a backtracking
line search to automatically adjust the damping in each SCF step. This line
search is based on a theoretically sound, accurate and inexpensive model for
the energy as a function of the damping parameter. In contrast to usual damped
SCF schemes, the resulting algorithm is fully automatic and does not require
the user to select a damping. We successfully apply it to a wide range of
challenging systems, including elongated supercells, surfaces and
transition-metal alloys.",2109.14018v3
2021-11-17,Spectral asymptotics for the vectorial damped wave equation,"The eigenfrequencies associated to a scalar damped wave equation are known to
belong to a band parallel to the real axis. In [Sj{\""o}00] J. Sj{\""o}strand
showed that up to a set of density 0, the eigenfrequencies are confined in a
thinner band determined by the Birkhoff limits of the damping term. In this
article we show that this result is still true for a vectorial damped wave
equation. In this setting the Lyapunov exponents of the cocycle given by the
damping term play the role of the Birkhoff limits of the scalar setting.",2111.08982v1
2021-12-13,Rotons and their damping in elongated dipolar Bose-Einstein condensates,"We discuss finite temperature damping of rotons in elongated Bose-condensed
dipolar gases, which are in the Thomas-Fermi regime in the tightly confined
directions. The presence of many branches of excitations which can participate
in the damping process, is crucial for the Landau damping and results in
significant increase of the damping rate. It is found, however, that even
rotons with energies close to the roton gap may remain fairly stable in systems
with the roton gap as small as 1nK.",2112.06835v2
2022-03-03,Stability results of locally coupled wave equations with local Kelvin-Voigt damping: Cases when the supports of damping and coupling coefficients are disjoint,"In this paper, we study the direct/indirect stability of locally coupled wave
equations with local Kelvin-Voigt dampings/damping and by assuming that the
supports of the dampings and the coupling coefficients are disjoint. First, we
prove the well-posedness, strong stability, and polynomial stability for some
one dimensional coupled systems. Moreover, under some geometric control
condition, we prove the well-posedness and strong stability in the
multi-dimensional case.",2203.01632v1
2022-03-12,Asymptotic expansion of solutions to the wave equation with space-dependent damping,"We study the large time behavior of solutions to the wave equation with
space-dependent damping in an exterior domain. We show that if the damping is
effective, then the solution is asymptotically expanded in terms of solutions
of corresponding parabolic equations. The main idea to obtain the asymptotic
expansion is the decomposition of the solution of the damped wave equation into
the solution of the corresponding parabolic problem and the time derivative of
the solution of the damped wave equation with certain inhomogeneous term and
initial data. The estimate of the remainder term is an application of weighted
energy method with suitable supersolutions of the corresponding parabolic
problem.",2203.06360v1
2022-10-27,Sharp polynomial decay for polynomially singular damping on the torus,"We study energy decay rates for the damped wave equation with unbounded
damping, without the geometric control condition. Our main decay result is
sharp polynomial energy decay for polynomially controlled singular damping on
the torus. We also prove that for normally $L^p$-damping on compact manifolds,
the Schr\""odinger observability gives $p$-dependent polynomial decay, and
finite time extinction cannot occur. We show that polynomially controlled
singular damping on the circle gives exponential decay.",2210.15697v3
2023-09-26,Qualitative properties of solutions to a nonlinear transmission problem for an elastic Bresse beam,"We consider a nonlinear transmission problem for a Bresse beam, which
consists of two parts, damped and undamped. The mechanical damping in the
damped part is present in the shear angle equation only, and the damped part
may be of arbitrary positive length. We prove well-posedness of the
corresponding PDE system in energy space and establish existence of a regular
global attractor under certain conditions on nonlinearities and coefficients of
the damped part only. Moreover, we study singular limits of the problem when
$l\to 0$ or $l\to 0$ simultaneously with $k_i\to +\infty$ and perform numerical
modelling for these processes.",2309.15171v2
2023-09-27,Dispersion and damping of ion-acoustic waves in the plasma with a regularized kappa-distribution,"The dispersion and damping of ion-acoustic waves in the plasma with a
regularized kappa-distribution are studied. The generalized dispersion relation
and damping rate are derived, which both depend significantly on the parameters
alpha and kappa. The numerical analyses show that the wave frequency and the
damping rate of ion-acoustic waves in the plasma with the regularized
kappa-distribution are both generally less than those in the plasma with the
kappa-distribution, and if kappa is less than a value, the ion-acoustic waves
and their damping rate exist in the plasma with the regularized
kappa-distribution.",2309.15885v1
2023-11-16,Near-optimal Closed-loop Method via Lyapunov Damping for Convex Optimization,"We introduce an autonomous system with closed-loop damping for first-order
convex optimization. While, to this day, optimal rates of convergence are only
achieved by non-autonomous methods via open-loop damping (e.g., Nesterov's
algorithm), we show that our system is the first one featuring a closed-loop
damping while exhibiting a rate arbitrarily close to the optimal one. We do so
by coupling the damping and the speed of convergence of the system via a
well-chosen Lyapunov function. We then derive a practical first-order algorithm
called LYDIA by discretizing our system, and present numerical experiments
supporting our theoretical findings.",2311.10053v1
2024-02-05,Fractional damping induces resonant behavior in the Duffing oscillator,"The interaction between the fractional order parameter and the damping
parameter can play a relevant role for introducing different dynamical
behaviors in a physical system. Here, we study the Duffing oscillator with a
fractional damping term. Our findings show that for certain values of the
fractional order parameter, the damping parameter, and the forcing amplitude
high oscillations amplitude can be induced. This phenomenon is due to the
appearance of a resonance in the Duffing oscillator only when the damping term
is fractional.",2402.02940v1
2024-03-13,Impact of Decoherence on Average Correlation,"This article presents a comprehensive study of the impact of decoherence on
the average correlation for pure quantum states. We explore two primary
mechanisms of decoherence: phase damping and amplitude damping, each having
distinct effects on quantum systems. Phase damping, which describes the loss of
quantum coherence without energy loss, primarily affects the phase
relationships between the components of a quantum system while amplitude
damping involves energy dissipation and also affects the state's occupation
probabilities. We show that the average correlation follows a predictable
decaying pattern in both scenarios. Our analysis can be understood in the
context of quantum computing, by focusing on how phase damping influences the
entanglement and correlation between qubits, key factors in quantum
computational efficiency and error correction protocols.",2403.10551v1
1998-02-18,Damping rates of hot Giant Dipole Resonances,"The damping rate of hot giant dipole resonances (GDR) is investigated.
Besides Landau damping we consider collisions and density fluctuations as
contributions to the damping of GDR. Within the nonequilibrium Green's function
method we derive a non-Markovian kinetic equation. The linearization of the
latter one leads to complex dispersion relations. The complex solution provides
the centroid energy and the damping width of giant resonances. The experimental
damping widths are the full width half maximum (FWHM) and can be reproduced by
the full width of the structure function. Within simple finite size scaling we
give a relation between the minimal interaction strength which is required for
a collective oscillation and the clustersize. We investigate the damping of
giant dipole resonances within a Skyrme type of interaction. Different
collision integrals are compared with each other in order to incorporate
correlations. The inclusion of a conserving relaxation time approximation
allows to find the $T^2$-dependence of the damping rate with a temperature
known from the Fermi-liquid theory. However, memory effects turn out to be
essential for a proper treatment of the damping of collective modes. We derive
a Landau like formula for the one--particle relaxation time similar to the
damping of zero sound.",9802052v2
2015-12-11,Ultra-low magnetic damping of a metallic ferromagnet,"The phenomenology of magnetic damping is of critical importance for devices
that seek to exploit the electronic spin degree of freedom since damping
strongly affects the energy required and speed at which a device can operate.
However, theory has struggled to quantitatively predict the damping, even in
common ferromagnetic materials. This presents a challenge for a broad range of
applications in spintronics and spin-orbitronics that depend on materials and
structures with ultra-low damping. Such systems enable many experimental
investigations that further our theoretical understanding of numerous magnetic
phenomena such as damping and spin-transport mediated by chirality and the
Rashba effect. Despite this requirement, it is believed that achieving
ultra-low damping in metallic ferromagnets is limited due to the scattering of
magnons by the conduction electrons. However, we report on a binary alloy of Co
and Fe that overcomes this obstacle and exhibits a damping parameter
approaching 0.0001, which is comparable to values reported only for
ferrimagnetic insulators. We explain this phenomenon by a unique feature of the
bandstructure in this system: The density of states exhibits a sharp minimum at
the Fermi level at the same alloy concentration at which the minimum in the
magnetic damping is found. This discovery provides both a significant
fundamental understanding of damping mechanisms as well as a test of
theoretical predictions.",1512.03610v1
2020-05-12,Effective Viscous Damping Enables Morphological Computation in Legged Locomotion,"Muscle models and animal observations suggest that physical damping is
beneficial for stabilization. Still, only a few implementations of mechanical
damping exist in compliant robotic legged locomotion. It remains unclear how
physical damping can be exploited for locomotion tasks, while its advantages as
sensor-free, adaptive force- and negative work-producing actuators are
promising. In a simplified numerical leg model, we studied the energy
dissipation from viscous and Coulomb damping during vertical drops with
ground-level perturbations. A parallel spring-damper is engaged between
touch-down and mid-stance, and its damper auto-disengages during mid-stance and
takeoff. Our simulations indicate that an adjustable and viscous damper is
desired. In hardware we explored effective viscous damping and adjustability
and quantified the dissipated energy. We tested two mechanical, leg-mounted
damping mechanisms; a commercial hydraulic damper, and a custom-made pneumatic
damper. The pneumatic damper exploits a rolling diaphragm with an adjustable
orifice, minimizing Coulomb damping effects while permitting adjustable
resistance. Experimental results show that the leg-mounted, hydraulic damper
exhibits the most effective viscous damping. Adjusting the orifice setting did
not result in substantial changes of dissipated energy per drop, unlike
adjusting damping parameters in the numerical model. Consequently, we also
emphasize the importance of characterizing physical dampers during real legged
impacts to evaluate their effectiveness for compliant legged locomotion.",2005.05725v2
2022-02-10,Non-stationary Anderson acceleration with optimized damping,"Anderson acceleration (AA) has a long history of use and a strong recent
interest due to its potential ability to dramatically improve the linear
convergence of the fixed-point iteration. Most authors are simply using and
analyzing the stationary version of Anderson acceleration (sAA) with a constant
damping factor or without damping. Little attention has been paid to
nonstationary algorithms. However, damping can be useful and is sometimes
crucial for simulations in which the underlying fixed-point operator is not
globally contractive. The role of this damping factor has not been fully
understood. In the present work, we consider the non-stationary Anderson
acceleration algorithm with optimized damping (AAoptD) in each iteration to
further speed up linear and nonlinear iterations by applying one extra
inexpensive optimization. We analyze this procedure and develop an efficient
and inexpensive implementation scheme. We also show that, compared with the
stationary Anderson acceleration with fixed window size sAA(m), optimizing the
damping factors is related to dynamically packaging sAA(m) and sAA(1) in each
iteration (alternating window size $m$ is another direction of producing
non-stationary AA). Moreover, we show by extensive numerical experiments that
the proposed non-stationary Anderson acceleration with optimized damping
procedure often converges much faster than stationary AA with constant damping
or without damping.",2202.05295v1
2023-06-30,A finite element method to compute the damping rate of oscillating fluids inside microfluidic nozzles,"We introduce a finite element method for computing the damping rate of fluid
oscillations in nozzles of drop-on-demand (DoD) microfluidic devices. Accurate
knowledge of the damping rates for the least-damped oscillation modes following
droplet ejection is paramount for assessing jetting stability at higher jetting
frequencies, as ejection from a non-quiescent meniscus can result in deviations
from nominal droplet properties. Computational fluid dynamics (CFD) simulations
often struggle to accurately predict meniscus damping in the limit of low
viscosity and high surface tension. Moreover, their use in design loops aimed
at optimizing the nozzle geometry for stable jetting is slow and
computationally expensive. The faster alternative we adopt here is to compute
the damping rate directly from the eigenvalues of the linearized problem.
Starting from a variational formulation of the linearized governing equations,
we obtain a generalized eigenvalue problem for the oscillation modes, and
approximate its solutions with a finite element method that uses Taylor-Hood
elements. We solve the matrix eigenvalue problem with a sparse, parallelized
implementation of the Krylov-Schur algorithm. The spatial shape and temporal
evolution (angular frequency and damping rate) of the set of least-damped
oscillation modes are obtained in a matter of minutes, compared to days for a
CFD simulation. We verify that the method can reproduce an analytical benchmark
problem, and then determine numerical convergence rates on two examples with
axisymmetric geometry. We also prove that the method is free of spurious modes
with zero or positive damping rates. The method's ability to quickly generate
accurate estimates of fluid oscillation damping rates makes it suitable for
integration into design loops for prototyping microfluidic nozzles.",2307.00094v1
2023-07-05,Optimal damping of vibrating systems: dependence on initial conditions,"Common criteria used for measuring performance of vibrating systems have one
thing in common: they do not depend on initial conditions of the system. In
some cases it is assumed that the system has zero initial conditions, or some
kind of averaging is used to get rid of initial conditions. The aim of this
paper is to initiate rigorous study of the dependence of vibrating systems on
initial conditions in the setting of optimal damping problems. We show that,
based on the type of initial conditions, especially on the ratio of potential
and kinetic energy of the initial conditions, the vibrating system will have
quite different behavior and correspondingly the optimal damping coefficients
will be quite different. More precisely, for single degree of freedom systems
and the initial conditions with mostly potential energy, the optimal damping
coefficient will be in the under-damped regime, while in the case of the
predominant kinetic energy the optimal damping coefficient will be in the
over-damped regime. In fact, in the case of pure kinetic initial energy, the
optimal damping coefficient is $+\infty$! Qualitatively, we found the same
behavior in multi degree of freedom systems with mass proportional damping. We
also introduce a new method for determining the optimal damping of vibrating
systems, which takes into account the peculiarities of initial conditions and
the fact that, although in theory these systems asymptotically approach
equilibrium and never reach it exactly, in nature and in experiments they
effectively reach equilibrium in some finite time.",2307.02352v2
2024-01-18,Multithermal apparent damping of slow waves due to strands with a Gaussian temperature distribution,"Context. Slow waves in solar coronal loops are strongly damped. The current
theory of damping by thermal conduction cannot explain some observational
features.\n Aims. We investigate the propagation of slow waves in a coronal
loop built up from strands of different temperatures. \n Methods. We consider
the loop to have a multithermal, Gaussian temperature distribution. The
different propagation speeds in different strands lead to an multithermal
apparent damping of the wave, similar to observational phase mixing. We use an
analytical model to predict the damping length and propagation speed for the
slow waves, including in imaging with filter telescopes. \n Results. We compare
the damping length due to this multithermal apparent damping with damping due
to thermal conduction and find that the multithermal apparent damping is more
important for shorter period slow waves. We have found the influence of
instrument filters on the wave's propagation speed and damping. This allows us
to compare our analytical theory to forward models of numerical simulations. \n
Conclusions. We find that our analytical model matches the numerical
simulations very well. Moreover, we offer an outlook for using the slow wave
properties to infer the loop's thermal properties.",2401.09803v1
2024-02-25,Variable martingale Hardy-Lorentz-Karamata spaces and their applications in Fourier Analysis,"In this paper, we introduce a new class of function spaces, which unify and
generalize Lorentz-Karamata spaces, variable Lorentz spaces and other several
classical function spaces. Based on the new spaces, we develop the theory of
variable martingale Hardy-Lorentz-Karamata spaces and apply it to Fourier
Analysis. To be precise, we discuss the basic properties of Lorentz-Karamata
spaces with variable exponents. We introduce five variable martingale
Hardy-Lorentz-Karamata spaces and characterize them via simple atoms as well as
via atoms. As applications of the atomic decompositions, dual theorems and the
generalized John-Nirenberg theorem for the new framework are presented.
Moreover, we obtain the boundedness of $\sigma$-sublinear operator defined on
variable martingale Hardy-Lorentz-Karamata spaces, which leads to martingale
inequalities and the relation of the five variable martingale
Hardy-Lorentz-Karamata spaces. Also, we investigate the boundedness of
fractional integral operators in this new framework. Finally, we deal with the
applications of variable martingale Hardy-Lorentz-Karamata spaces in Fourier
analysis by using the previous results. More precisely, we show that the
partial sums of the Walsh-Fourier series converge to the function in norm if
$f\in L_{p(\cdot),q,b}$ with $1<p_-\le p_+<\infty$. The Fej\'{e}r summability
method is also studied and it is proved that the maximal Fej\'{e}r operator is
bounded from variable martingale Hardy-Lorentz-Karamata spaces to variable
Lorentz-Karamata spaces. As a consequence, we get conclusions about almost
everywhere and norm convergence of Fej\'{e}r means. The results obtained in
this paper generalize the results for martingale Hardy-Lorentz-Karamata spaces
and variable martingale Hardy-Lorentz spaces. Especially, we remove the
condition that $b$ is nondecreasing in previous literature.",2402.16133v1
1999-04-30,Theoretical Analysis of CPT and Lorentz Tests in Penning Traps,"The CPT theorem has been tested to very high precision in a variety of
experiments involving particles and antiparticles confined within Penning
traps. These tests include comparisons of anomalous magnetic moments and
charge-to-mass ratios of electrons and positrons, protons and antiprotons, and
hydrogen ions and antiprotons. We present a theoretical analysis of possible
signals for CPT and Lorentz violation in these systems. We use the framework of
Colladay and Kosteleck\'y, which consists of a general extension of the $SU(3)
\times SU(2) \times U(1)$ standard model including possible CPT and Lorentz
violations arising from spontaneous symmetry breaking at a fundamental level,
such as in string theory. We work in the context of an extension of quantum
electrodynamics to examine CPT and Lorentz tests in Penning traps. Our analysis
permits a detailed study of the effectiveness of experimental tests of CPT and
Lorentz symmetry performed in Penning traps. We describe possible signals that
might appear in principle, and estimate bounds on CPT and Lorentz violation
attainable in present and future experiments.",9904508v1
2005-01-14,Tests of Lorentz Violation in Atomic and Optical Physics,"Atomic physics can probe the Lorentz and CPT symmetries at the Planck level.
Bounds on coefficients for Lorentz violation have been found using atomic
clocks, masers, electromagnetic cavities, and Penning traps, among others, and
in future it may be possible to place bounds using spectroscopy of antihydrogen
atoms. The CPT '04 Meeting on CPT and Lorentz Symmetry was held in August 2004
in Bloomington, Indiana, USA, and covered Lorentz violation in all branches of
physics. This report gives an overview of the recent advances in
Lorentz-symmetry studies in atomic and optical physics.",0501127v1
1998-09-01,The Einstein - Lorentz Dispute Revisited,"Lorentz [of the Lorentz transforms and Lorentz contractions fame] contended
against Einstein that there had to be a medium in which electro-magnetic waves
exist and propagate, and that that would of necessity be an absolute frame of
reference for the universe. Einstein won that dispute contending that
electro-magnetic waves needed no medium and that there was no absolute frame of
reference. But, that victory was in a conflict of the Lorentz opinion opposed
to the Einstein opinion combined with the substantial other successes and
reputation or Einstein. It was not a victory of solid reasoning nor
demonstrated factual evidence. Now solid reasoning and new data not available
to Einstein and Lorentz show that Lorentz was correct and that Einstein's
Theory of Relativity should correctly be termed Einstein's Principle of
Invariance. It is shown that Einstein's comprehensive relativity and denial of
an absolute frame of reference for the universe are incorrect and that the
universe has an absolute universal prime frame of reference. The significance
of this correction in its relation to the interaction of science and society is
then presented.",9808052v5
2004-07-28,The language of Einstein spoken by optical instruments,"Einstein had to learn the mathematics of Lorentz transformations in order to
complete his covariant formulation of Maxwell's equations. The mathematics of
Lorentz transformations, called the Lorentz group, continues playing its
important role in optical sciences. It is the basic mathematical language for
coherent and squeezed states. It is noted that the six-parameter Lorentz group
can be represented by two-by-two matrices. Since the beam transfer matrices in
ray optics is largely based on two-by-two matrices or $ABCD$ matrices, the
Lorentz group is bound to be the basic language for ray optics, including
polarization optics, interferometers, lens optics, multilayer optics, and the
Poincar\'e sphere. Because the group of Lorentz transformations and ray optics
are based on the same two-by-two matrix formalism, ray optics can perform
mathematical operations which correspond to transformations in special
relativity. It is shown, in particular, that one-lens optics provides a
mathematical basis for unifying the internal space-time symmetries of massive
and massless particles in the Lorentz-covariant world.",0407222v1
2007-06-27,Lorentz anomaly in the semi-light-cone gauge superstrings,"We study the Lorentz invariance of D=4 and 6 superstrings in the
double-spinor formalism, which are equivalent to the D=4 and 6 superstrings in
the pure-spinor formalism in the sense of the BRST cohomology. We first
re-examine how the conformal and Lorentz anomalies appear in the D=4 and 6
Green-Schwarz superstrings in the semi-light-cone gauge in the framework of
BRST quantization. We construct a set of BRST invariant Lorentz generators and
show that they do not form a closed algebra, even cohomologically. We then turn
to the construction of Lorentz generators in the D=4 and 6 double-spinor
superstrings, and show that the Lorentz invariance is again anomalous. We also
discuss the relation between the anomaly-free Lorentz generators in the
lower-dimensional pure-spinor formalisms and that obtained in this paper.",0706.3982v3
2011-02-19,"Lorentz Harmonics, Squeeze Harmonics, and their Physical Applications","Among the symmetries in physics, the rotation symmetry is most familiar to
us. It is known that the spherical harmonics serve useful purposes when the
world is rotated. Squeeze transformations are also becoming more prominent in
physics, particularly in optical sciences and in high-energy physics. As can be
seen from Dirac's light-cone coordinate system, Lorentz boosts are squeeze
transformations. Thus the squeeze transformation is one of the fundamental
transformations in Einstein's Lorentz-covariant world. It is possible to define
a complete set of orthonormal functions defined for one Lorentz frame. It is
shown that the same set can be used for other Lorentz frames. Transformation
properties are discussed. Physical applications are discussed in both optics
and high-energy physics. It is shown that the Lorentz harmonics provide the
mathematical basis for squeezed states of light. It is shown also that the same
set of harmonics can be used for understanding Lorentz-boosted hadrons in
high-energy physics. It is thus possible to transmit physics from one branch of
physics to the other branch using the mathematical basis common to them.",1102.4000v1
2012-06-28,Tests of Lorentz and CPT violation with MiniBooNE neutrino oscillation excesses,"Violation of Lorentz invariance and CPT symmetry is a predicted phenomenon of
Planck-scale physics. Various types of data are analyzed to search for Lorentz
violation under the Standard-Model Extension (SME) framework, including
neutrino oscillation data. MiniBooNE is a short-baseline neutrino oscillation
experiment at Fermilab. The measured excesses from MiniBooNE cannot be
reconciled within the neutrino Standard Model; thus it might be a signal of new
physics, such as Lorentz violation. We have analyzed the sidereal time
dependence of MiniBooNE data for signals of the possible breakdown of Lorentz
invariance in neutrinos. In this brief review, we introduce Lorentz violation,
the neutrino sector of the SME, and the analysis of short-baseline neutrino
oscillation experiments. We then present the results of the search for Lorentz
violation in MiniBooNE data. This review is based on the published result
(ArXiv:1109.3480).",1206.6915v3
2012-12-18,Coupled scalar fields Oscillons and Breathers in some Lorentz Violating Scenarios,"In this work we discuss the impact of the breaking of the Lorentz symmetry on
the usual oscillons, the so-called flat-top oscillons, and the breathers. Our
analysis is performed by using a Lorentz violation scenario rigorously derived
in the literature. We show that the Lorentz violation is responsible for the
origin of a kind of deformation of the configuration, where the field
configuration becomes oscillatory in a localized region near its maximum value.
Furthermore, we show that the Lorentz breaking symmetry produces a displacement
of the oscillon along the spatial direction, the same feature is present in the
case of breathers. We also show that the effect of a Lorentz violation in the
flat-top oscillon solution is responsible by the shrinking of the flat-top.
Furthermore, we find analytically the outgoing radiation, this result indicates
that the amplitude of the outgoing radiation is controlled by the Lorentz
breaking parameter, in such away that this oscillon becomes more unstable than
its symmetric counterpart, however, it still has a long living nature.",1212.4448v4
2016-04-19,Lorentz atom revisited by solving Abraham-Lorentz equation of motion,"By solving the non-relativistic Abraham-Lorentz (AL) equation, I demonstrate
that AL equation of motion is not suited for treating the Lorentz atom, because
a steady-state solution does not exist. The AL equation serves as a tool,
however, for deducing appropriate parameters $\Omega,\Gamma$ to be used with
the equation of forced oscillations in modelling the Lorentz atom. The electric
polarizability, which many authors ""derived"" from AL equation in recent years,
is found to violate Kramers-Kronig relations rendering obsolete the extracted
photon-absorption rate, for example. Fortunately, errors turn out to be small
quantitatively, as long as light frequency $\omega$ is neither too close to nor
too far from resonance frequency $\Omega$. Polarizability and absorption cross
section are derived for the Lorentz atom by purely classical reasoning and
shown to agree with quantum-mechanical calculations of the same quantities. In
particular, oscillator parameters $\Omega,\,\Gamma$ deduced by treating the
atom as a quantum oscillator are found equivalent to those derived from
classical AL equation. The instructive comparison provides a deep insight into
understanding the great success of Lorentz's model which was suggested long
before the advent of quantum theory.",1604.05688v1
2016-10-03,Self-dual solitons in a $CPT$-odd and Lorentz-violating gauged $O(3)$ sigma model,"We have performed a complete study of self-dual configurations in a $CPT$-odd
and Lorentz-violating gauged $O(3)$ nonlinear sigma model. We have consistently
implemented the Bogomol'nyi-Prasad-Sommerfield (BPS) formalism and obtained the
correspondent differential first-order equations describing electrically
charged self-dual configurations. The total energy and magnetic flux of the
vortices, besides being proportional to the winding number, also depend
explicitly on the Lorentz-violating coefficients belonging to the sigma sector.
The total electrical charge is proportional to the magnetic flux such as it
occurs in Chern-Simons models. The Lorentz violation in the sigma sector allows
one to interpolate between Lorentz-violating versions of some sigma models: the
gauged $O(3)$ sigma model and the Maxwell-Chern-Simons $O(3)$ sigma model. The
Lorentz violation enhances the amplitude of the magnetic field and BPS energy
density near the origin, augmenting the deviation in relation to the solutions
deprived of Lorentz violation.",1610.00654v1
2017-03-17,Scaling of Relativistic Shear Flows with Bulk Lorentz Factor,"We compare Particle-in-Cell simulation results of relativistic electron-ion
shear flows with different bulk Lorentz factors, and discuss their implications
for spine-sheath models of blazar versus gamma-ray burst (GRB) jets.
Specifically, we find that most properties of the shear boundary layer scale
with the bulk Lorentz factor: the lower the Lorentz factor, the thinner the
boundary layer, and the weaker the self-generated fields. Similarly, the
energized electron spectrum peaks at an energy near the ion drift energy, which
increases with bulk Lorentz factor, and the beaming of the accelerated
electrons gets narrower with increasing Lorentz factor. This predicts a strong
correlation between emitted photon energy, angular beaming and temporal
variability with the bulk Lorentz factor. Observationally, we expect systematic
differences between the high-energy emissions of blazars and GRB jets.",1703.06135v1
2011-11-28,Dispersion Relations Explaining OPERA Data From Deformed Lorentz Transformation,"OPERA collaboration has reported evidence of superluminal phenomenon for
neutrinos. One of the possible ways to explain the superluminality is to have
Lorentz symmetry violated. It has been shown that dispersion relations put
forwards has the problem of physics laws vary in different inertial frames
leading to conflicting results on Cherenkov-like radiation, pion decay and high
energy neutrino cosmic ray. For theories with deformed Lorentz symmetry, by
modifying conservation laws corresponding to energy and momentum in the usual
Lorentz invariant theory, it is possible to have superluminal effect and at the
same time avoid to have conflicts encountered in Lorentz violating theories. We
study dispersion relations from deformed Lorentz symmetry. We find that it is
possible to have dispersion relations which can be consistent with data on
neutrinos. We show that once the superluminality $\delta v$ as a function of
energy is known the corresponding dispersion relation in the deformed Lorentz
symmetry can be determined.",1111.6330v2
2019-07-04,Testing Lorentz violation by the comparison of atomic clocks,"A more complete theoretical model of testing Lorentz violation by the
comparison of atomic clocks is developed in the Robertson-Mansouri-Sexl
kinematic framework. As this frame postulates the deviation of the coordinate
transformation from the Lorentz transformation, from the viewpoint of the
transformation violations on time and space, the LI violating effect in the
atomic clock comparison can be explained as two parts: time-delay effect
$\alpha \frac {v^2}{c^2}$ and structure effect $-\frac {\beta+2\delta}{3} \frac
{v^2}{c^2}$. Standard model extension is a widely used dynamic frame to
characterize the Lorentz violation, in which a space-orientation dependence
violating background field is regarded as the essential reason for the Lorentz
violation effect. Compared with the RMS frame which only indicates the
kinematic properties with the coordinate transformation, this dynamic frame
provides a more complete and clear description for the Lorentz violation
effect.",1907.02176v1
2020-04-09,Unusual stationary state in Brownian systems with Lorentz force,"In systems with overdamped dynamics, the Lorentz force reduces the
diffusivity of a Brownian particle in the plane perpendicular to the magnetic
field. The anisotropy in diffusion implies that the Fokker-Planck equation for
the probabiliy distribution of the particle acquires a tensorial coefficient.
The tensor, however, is not a typical diffusion tensor due to the antisymmetric
elements which account for the fact that Lorentz force curves the trajectory of
a moving charged particle. This gives rise to unusual dynamics with features
such as additional Lorentz fluxes and a nontrivial density distribution, unlike
a diffusive system. The equilibrium properties are, however, unaffected by the
Lorentz force. Here we show that by stochastically resetting the Brownian
particle, a nonequilibrium steady state can be created which preserves the
hallmark features of dynamics under Lorentz force. We then consider a
minimalistic example of spatially inhomogeneous magnetic field, which shows how
Lorentz fluxes fundamentally alter the boundary conditions giving rise to an
unusual stationary state.",2004.04471v2
2021-01-23,Signature of Lorentz Violation in Continuous Gravitational-Wave Spectra of Ellipsoidal Neutron Stars,"We study effects of Lorentz-invariance violation on the rotation of neutron
stars (NSs) in the minimal gravitational Standard-Model Extension framework,
and calculate the quadrupole radiation generated by them. Aiming at testing
Lorentz invariance with observations of continuous gravitational waves (GWs)
from rotating NSs in the future, we compare the GW spectra of a rotating
ellipsoidal NS under Lorentz-violating gravity with those of a
Lorentz-invariant one. The former are found to possess frequency components
higher than the second harmonic, which does not happen for the latter,
indicating those higher frequency components to be potential signatures of
Lorentz violation in continuous GW spectra of rotating NSs.",2101.09431v1
2020-09-22,Squeezing the Parameter Space for Lorentz Violation in the Neutrino Sector by Additional Decay Channels,"The hypothesis of Lorentz violation in the neutrino sector has intrigued
scientists for the last two to three decades. A number of theoretical arguments
support the emergence of such violations first and foremost for neutrinos,
which constitute the ""most elusive"" and ""least interacting"" particles known to
mankind. It is of obvious interest to place stringent bounds on the
Lorentz-violating parameters in the neutrino sector. In the past, the most
stringent bounds have been placed by calculating the probability of neutrino
decay into a lepton pair, a process made kinematically feasible by Lorentz
violation in the neutrino sector, above a certain threshold. However, even more
stringent bounds can be placed on the Lorentz-violating parameters if one takes
into account, additionally, the possibility of neutrino splitting, i.e., of
neutrino decay into a neutrino of lower energy, accompanied by ""neutrino-pair
Cerenkov radiation"". This process has negligible threshold and can be used to
improve the bounds on Lorentz-violating parameters in the neutrino sector.
Finally, we take the opportunity to discuss the relation of Lorentz and gauge
symmetry breaking, with a special emphasis on the theoretical models employed
in our calculations.",2009.11947v1
2022-10-05,Searching for Lorentz-violating Signatures from Astrophysical Photon Observations,"As a basic symmetry of Einstein's theory of special relativity, Lorentz
invariance has withstood very strict tests. But there are still motivations for
such tests. Firstly, many theories of quantum gravity suggest violations of
Lorentz invariance at the Planck energy scale. Secondly, even minute deviations
from Lorentz symmetry can accumulate as particle travel across large distances,
leading to detectable effects at attainable energies. Thanks to their long
baselines and high-energy emission, astrophysical observations provide
sensitive tests of Lorentz invariance in the photon sector. In this paper, I
briefly introduce astrophysical methods that we adopted to search for
Lorentz-violating signatures, including vacuum dispersion and vacuum
birefringence.",2210.02114v1
2023-11-21,Electrodynamics with violations of Lorentz and U(1) gauge symmetries and their Hamiltonian structure,"This article aims to study the Lorentz/U(1) gauge symmetry-breaking
electrodynamics in the framework of the Standard-Model Extension and analyze
the Hamiltonian structure for the theory with a specific dimension $d\leq 4$ of
Lorentz breaking operators. For this purpose, we consider a general quadratic
action of the modified electrodynamics with Lorentz/gauge-breaking operators
and calculate the number of independent components of the operators at
different dimensions in gauge invariance and breaking. With this general
action, we then analyze how the Lorentz/gauge symmetry-breaking can change the
Hamiltonian structure of the theories by considering Lorentz/gauge-breaking
operators with dimension $d\leq 4$ as examples. We show that the
Lorentz-breaking operators with gauge invariance do not change the classes of
the constraints of the theory and the number of the physical degrees of freedom
of the standard Maxwell's electrodynamics. When the U(1) gauge
symmetry-breaking operators are present, the theories in general lack
first-class constraint and have one additional physical degree of freedom,
compared to the standard Maxwell's electrodynamics.",2311.12357v1
2023-12-05,Rescuing the Unruh Effect in Lorentz Violating Gravity,"While the robustness of Hawking radiation in the presence of UV Lorentz
breaking is well-established, the Unruh effect has posed a challenge, with a
large literature concluding that even the low-energy restoration of Lorentz
invariance may not be sufficient to sustain this phenomenon. Notably, these
previous studies have primarily focused on Lorentz-breaking matter on a
conventional Rindler wedge. In this work, we demonstrate that considering the
complete structure of Lorentz-breaking gravity, specifically the presence of a
hypersurface orthogonal aether field, leads to the selection of a new Rindler
wedge configuration characterized by a uniformly accelerated aether flow. This
uniform acceleration provides a reference scale for comparison with the
Lorentz-breaking one, thus ensuring the persistence of the Unruh effect in this
context. We establish this by calculating the expected temperature using a
Bogolubov approach, and by analyzing the response of a uniformly accelerated
detector. We suggest that this resilience of the Unruh effect opens interesting
possibilities towards future developments for using it as a tool to constrain
Lorentz breaking theories of gravity.",2312.03070v1
2002-05-29,On the fate of Lorentz symmetry in loop quantum gravity and noncommutative spacetimes,"I analyze the deformation of Lorentz symmetry that holds in certain
noncommutative spacetimes and the way in which Lorentz symmetry is broken in
other noncommutative spacetimes. I also observe that discretization of areas
does not necessarily require departures from Lorentz symmetry. This is due to
the fact that Lorentz symmetry has no implications for exclusive measurement of
the area of a surface, but it governs the combined measurements of the area and
the velocity of a surface. In a quantum-gravity theory Lorentz symmetry can be
consistent with area discretization, but only when the observables ``area of
the surface"" and ""velocity of the surface"" enjoy certain special properties. I
argue that the status of Lorentz symmetry in the loop-quantum-gravity approach
requires careful scrutiny, since areas are discretized within a formalism that,
at least presently, does not include an observable ""velocity of the surface"".
In general it may prove to be very difficult to reconcile Lorentz symmetry with
area discretization in theories of canonical quantization of gravity, because a
proper description of Lorentz symmetry appears to require that the
fundamental/primary role be played by the surface's world-sheet, whose
""projection"" along the space directions of a given observer describes the
observable area, whereas the canonical formalism only allows the introduction
as primary entities of observables defined at a fixed (common) time, and the
observers that can be considered must share that time variable.",0205125v1
2005-06-06,Overview of the SME: Implications and Phenomenology of Lorentz Violation,"The Standard Model Extension (SME) provides the most general
observer-independent field theoretical framework for investigations of Lorentz
violation. The SME lagrangian by definition contains all Lorentz-violating
interaction terms that can be written as observer scalars and that involve
particle fields in the Standard Model and gravitational fields in a generalized
theory of gravity. This includes all possible terms that could arise from a
process of spontaneous Lorentz violation in the context of a more fundamental
theory, as well as terms that explicitly break Lorentz symmetry. An overview of
the SME is presented, including its motivations and construction. Some of the
theoretical issues arising in the case of spontaneous Lorentz violation are
discussed, including the question of what happens to the Nambu-Goldstone modes
when Lorentz symmetry is spontaneously violated and whether a Higgs mechanism
can occur. A minimal version of the SME in flat Minkowski spacetime that
maintains gauge invariance and power-counting renormalizability is used to
search for leading-order signals of Lorentz violation. Recent Lorentz tests in
QED systems are examined, including experiments with photons, particle and
atomic experiments, proposed experiments in space and experiments with a
spin-polarized torsion pendulum.",0506054v1
2003-12-08,A New Gauge-Invariant Regularization Scheme Based on Lorentz-Invariant Noncommutative Quantum Field Theory,"The IR/UV mixing in the non-commutative (NC) field theory is investigated in
Carlson-Carone-Zobin (CCZ) formalism of Lorentz-invariant NC field theory
provided that the fields are `independent' of the `internal' coordinates
$\theta^{\mu\nu}$. A new regularization scheme called NC regularizatioon is
then proposed, which removes the Lorentz-invariant IR singularity from the
theory. It requires the usual UV limit $\Lambda\to \infty$ to be accompanied
with the commutative limit $a\to 0$ with $\Lambda^2a^2$ fixed, where $a$ is the
length parameter in the theory. The new UV limit gives the usual renormalized
amplitude of the one-loop self-energy diagram of $\phi^3$ model. It is shown
that the new regularization is gauge-invariant, that is, the non-transverse
part of the vacuum polarization in QED is automatically transverse in
Lorentz-invariant NCQED but the two transverse pieces, one of which is already
transverse in QED, possesses Lorentz-invariant IR singularity which should be
`subtracted off' at zero external momentum squared. The subtraction leads to
the same result as the renormalized one by Pauli-Villars or dimensional
regularizations. Other diagrams with three-point vertices which contribute to
the photon self-energy in Lorentz-non-invariant NCQED all vanish due to Lorentz
invariance under the assumption adopted, while the tadpole diagram gives a
finite contribution to the charge renormalization which vanishes if $
Lambda^2a^2\to 0$. Lorentz-invariant NC $\phi^4$ and scalar Yukawa models are
also discussed in the one-loop approximation. A comment is made that
Lorentz-invariance might lead to a decoupling of U(1) part from SU(N) in NC
U(N) gauge theory.",0312080v2
2004-12-29,"Spontaneous Lorentz Violation, Nambu-Goldstone Modes, and Gravity","The fate of the Nambu-Goldstone modes arising from spontaneous Lorentz
violation is investigated. Using the vierbein formalism, it is shown that up to
10 Lorentz and diffeomorphism Nambu-Goldstone modes can appear and that they
are contained within the 10 modes of the vierbein associated with gauge degrees
of freedom in a Lorentz-invariant theory. A general treatment of spontaneous
local Lorentz and diffeomorphism violation is given for various spacetimes, and
the fate of the Nambu-Goldstone modes is shown to depend on both the spacetime
geometry and the dynamics of the tensor field triggering the spontaneous
Lorentz violation. The results are illustrated within the general class of
bumblebee models involving vacuum values for a vector field. In Minkowski and
Riemann spacetimes, the bumblebee model provides a dynamical theory generating
a photon as a Nambu-Goldstone boson for spontaneous Lorentz violation. The
Maxwell and Einstein-Maxwell actions are automatically recovered in axial
gauge. Associated effects of potential experimental relevance include
Lorentz-violating couplings in the matter and gravitational sectors of the
Standard-Model Extension and unconventional Lorentz-invariant couplings. In
Riemann-Cartan spacetime, the possibility also exists of a Higgs mechanism for
the spin connection, leading to the absorption of the propagating
Nambu-Goldstone modes into the torsion component of the gravitational field.",0412320v2
2011-06-10,On Lorentz-Violating Supersymmetric Quantum Field Theories,"We study the possibility of constructing Lorentz-violating supersymmetric
quantum field theories under the assumption that these theories have to be
described by lagrangians which are renormalizable by weighted power counting.
Our investigation starts from the observation that at high energies
Lorentz-violation and the usual supersymmetry algebra are algebraically
compatible. Demanding linearity of the supercharges we see that the requirement
of renormalizability drastically restricts the set of possible
Lorentz-violating supersymmetric theories. In particular, in the case of
supersymmetric gauge theories the weighted power counting has to coincide with
the usual one and the only Lorentz-violating operators are introduced by some
weighted constant c that explicitly appears in the supersymmetry algebra. This
parameter does not renormalize and has to be very close to the speed of light
at low energies in order to satisfy the strict experimental bounds on Lorentz
violation. The only possible models with non trivial Lorentz-violating
operators involve neutral chiral superfields and do not have a gauge invariant
extension. We conclude that, under the assumption that high-energy physics can
be described by a renormalizable Lorentz-violating extensions of the Standard
Model, the Lorentz fine tuning problem does not seem solvable by the
requirement of supersymmetry.",1106.2035v2
2014-08-11,"Applications of Lorentz force in medical acoustics: Lorentz force hydrophone, Lorentz Force Electrical Impedance Tomography, Imaging of shear waves induced by Lorentz force","The ability of the Lorentz force to link a mechanical displacement to an
electrical current presents a strong interest for medical acoustics, and three
applications were studied in this thesis. In the first part of this work, a
hydrophone was developed for mapping the particle velocity of an acoustic
field. This hydrophone was constructed using a thin copper wire and an external
magnetic field. A model was elaborated to determine the relationship between
the acoustic pressure and the measured electrical current, which is induced by
Lorentz force when the wire vibrates in the acoustic field of an ultrasound
transducer. The built prototype was characterized and its spatial resolution,
frequency response, sensitivity, robustness and directivity response were
investigated. An imaging method called Lorentz Force Electrical Impedance
Tomography was also studied. In this method, a biological tissue is vibrated by
ultrasound in a magnetic field, which induces an electrical current by Lorentz
force. The electrical impedance of the tissue can be deduced from the
measurement of the current. This technique was applied for imaging a gelatin
phantom, a beef muscle sample, and a thermal lesion in a chicken breast sample.
This showed the method may be useful for providing additional contrast to
conventional ultrasound imaging. Finally, this thesis demonstrated that shear
waves can be generated in soft tissues using Lorentz force. This work was
performed by applying an electrical current with two electrodes in a soft solid
placed in a magnetic field. Shear waves were observed in gelatin phantom and
liver sample. The speed of the shear waves were used to compute elasticity and
their source to map the electrical conductivity of the samples.",1408.2574v1
2020-08-21,Is the local Lorentz invariance of general relativity implemented by gauge bosons that have their own Yang-Mills-like action?,"General relativity with fermions has two independent symmetries: general
coordinate invariance and local Lorentz invariance. General coordinate
invariance is implemented by the Levi-Civita connection and by Cartan's tetrads
both of which have as their action the Einstein-Hilbert action. It is suggested
here that local Lorentz invariance is implemented not by a combination of the
Levi-Civita connection and Cartan's tetrads known as the spin connection, but
by independent Lorentz bosons L_i that gauge the Lorentz group, that couple to
fermions like Yang-Mills fields, and that have their own Yang-Mills-like
action. A nonsingular 4 x 4 hermitian scalar field h is needed to make the
action of the Lorentz bosons invariant under local Lorentz transformations.
Lorentz bosons couple to fermion number and generate a spin-dependent static
potential that violates the weak equivalence principle. If a Higgs mechanism
makes them massive, then the static potential also violates the inverse-square
law. Experiments put upper bounds on the strength of such a potential for
masses m_L < 20 eV. These upper limits imply that Lorentz bosons, if they
exist, are nearly stable and contribute to dark matter.",2008.10381v3
1996-06-07,Abundances at High Redshifts: the Chemical Enrichment History of Damped Lyman-alpha Galaxies,"Damped Lyman-alpha absorption systems found in the spectra of high redshift
quasars are believed to trace the interstellar gas in high redshift galaxies.
In this paper, we study the elemental abundances of C, N, O, Al, Si, S, Cr, Mn,
Fe, Ni, and Zn in a sample of 14 damped Lyman-alpha systems using high quality
echelle spectra of quasars obtained with the 10m Keck telescope. These
abundances are combined with similar measurements in the literature in order to
investigate the chemical evolution of damped Lyman-alpha galaxies in the
redshift range 0.7<z<4.4. Among the things investigated are: the metallicity
distribution of damped Lyman-alpha galaxy, its evolution with redshift (ie,
age-metallicity relation), the relative abundance patterns of the heavy metals
and implications for their nucleosynthetic origin, the effects of dust, the
nature of the star formation process in damped Lyman-alpha galaxies, and the
nature of damped Lyman-alpha galaxies themselves.",9606044v1
1998-07-17,Chaotic scattering on surfaces and collisional damping of collective modes,"The damping of hot giant dipole resonances is investigated. The contribution
of surface scattering is compared with the contribution from interparticle
collisions. A unified response function is presented which includes surface
damping as well as collisional damping. The surface damping enters the response
via the Lyapunov exponent and the collisional damping via the relaxation time.
The former is calculated for different shape deformations of quadrupole and
octupole type. The surface as well as the collisional contribution each
reproduce almost the experimental value, therefore we propose a proper
weighting between both contributions related to their relative occurrence due
to collision frequencies between particles and of particles with the surface.
We find that for low and high temperatures the collisional contribution
dominates whereas the surface damping is dominant around the temperatures
$\sqrt{3}/2\pi$ of the centroid energy.",9807185v4
2000-09-08,Probing High-Redshift Disks with Damped Lyman Alpha Systems,"Evidence is presented that the damped Lyman alpha absorption systems are the
high-redshift (z > 3) progenitors of galaxy disks. I discuss kinematic evidence
that the damped Lyman Alpha systems are rotating disks. I also discuss
implications of the lack of metal-poor damped Lyman alpha systems with line
width Delta v > 100 {\kms}. I then present new evidence stemming from
correlations between element-abundance ratios and [Fe/H], which connects damped
systems to the thick stellar disk of the Galaxy. I discuss the connections
between damped Lyman alpha systems and Lyman break galaxies, and how [CII] 158
micron emission from damped Lyman alpha systems discriminates among competing
theories of galaxy formation. ~",0009126v1
2006-09-10,Damping of Compressional MHD Waves In Quiescent Prominences and Prominence-Corona Transition Region (PCTR),"The effects of radiative losses due to Newtonian cooling and MHD turbulence
have been considered to examine the spatial damping of linear compressional
waves in quiescent prominences and prominence-corona transition region (PCTR).
The radiative losses give acceptable damping lengths for the slow mode wave for
the radiative relaxation time in the range (10-1000s). From prominence
seismology, the values of opacity and turbulent kinematic viscosity have been
inferred. It has been found that for a given value of radiative relaxation
time, the high frequency slow mode waves are highly damped. We have also
investigated the possible role of MHD turbulence in damping of MHD waves and
found a turbulent viscosity can re-produce the observed damping time and
damping length in prominences, especially in PCTR.",0609266v1
1997-10-14,Damping of low-energy excitations of a trapped Bose condensate at finite temperatures,"We present the theory of damping of low-energy excitations of a trapped Bose
condensate at finite temperatures, where the damping is provided by the
interaction of these excitations with the thermal excitations. We emphasize the
key role of stochastization in the behavior of the thermal excitations for
damping in non-spherical traps. The damping rates of the lowest excitations,
following from our theory, are in fair agreement with the data of recent JILA
and MIT experiments. The damping of quasiclassical excitations is determined by
the condensate boundary region, and the result for the damping rate is
drastically different from that in a spatially homogeneous gas.",9710128v3
2001-12-09,Soliton dynamics in damped and forced Boussinesq equations,"We investigate the dynamics of a lattice soliton on a monatomic chain in the
presence of damping and external forces. We consider Stokes and hydrodynamical
damping. In the quasi-continuum limit the discrete system leads to a damped and
forced Boussinesq equation. By using a multiple-scale perturbation expansion up
to second order in the framework of the quasi-continuum approach we derive a
general expression for the first-order velocity correction which improves
previous results. We compare the soliton position and shape predicted by the
theory with simulations carried out on the level of the monatomic chain system
as well as on the level of the quasi-continuum limit system. For this purpose
we restrict ourselves to specific examples, namely potentials with cubic and
quartic anharmonicities as well as the truncated Morse potential, without
taking into account external forces. For both types of damping we find a good
agreement with the numerical simulations both for the soliton position and for
the tail which appears at the rear of the soliton. Moreover we clarify why the
quasi-continuum approximation is better in the hydrodynamical damping case than
in the Stokes damping case.",0112148v1
2006-04-17,The Highly Damped Quasinormal Modes of $d$-dimensional Reissner-Nordstrom Black Holes in the Small Charge Limit,"We analyze in detail the highly damped quasinormal modes of $d$-dimensional
Reissner-Nordstr$\ddot{\rm{o}}$m black holes with small charge, paying
particular attention to the large but finite damping limit in which the
Schwarzschild results should be valid. In the infinite damping limit, we
confirm using different methods the results obtained previously in the
literature for higher dimensional Reissner-Nordstr$\ddot{\rm{o}}$m black holes.
Using a combination of analytic and numerical techniques we also calculate the
transition of the real part of the quasinormal mode frequency from the
Reissner-Nordstr$\ddot{\rm{o}}$m value for very large damping to the
Schwarzschild value of $\ln(3) T_{bh}$ for intermediate damping. The real
frequency does not interpolate smoothly between the two values. Instead there
is a critical value of the damping at which the topology of the
Stokes/anti-Stokes lines change, and the real part of the quasinormal mode
frequency dips to zero.",0604073v2
2005-02-16,Damping signatures in future neutrino oscillation experiments,"We discuss the phenomenology of damping signatures in the neutrino
oscillation probabilities, where either the oscillating terms or the
probabilities can be damped. This approach is a possibility for tests of
non-oscillation effects in future neutrino oscillation experiments, where we
mainly focus on reactor and long-baseline experiments. We extensively motivate
different damping signatures due to small corrections by neutrino decoherence,
neutrino decay, oscillations into sterile neutrinos, or other mechanisms, and
classify these signatures according to their energy (spectral) dependencies. We
demonstrate, at the example of short baseline reactor experiments, that damping
can severely alter the interpretation of results, e.g., it could fake a value
of $\sin(2\theta_{13})$ smaller than the one provided by Nature. In addition,
we demonstrate how a neutrino factory could constrain different damping models
with emphasis on how these different models could be distinguished, i.e., how
easily the actual non-oscillation effects could be identified. We find that the
damping models cluster in different categories, which can be much better
distinguished from each other than models within the same cluster.",0502147v2
1997-07-23,Riccati parameter modes from Newtonian free damping motion by supersymmetry,"We determine the class of damped modes \tilde{y} which are related to the
common free damping modes y by supersymmetry. They are obtained by employing
the factorization of Newton's differential equation of motion for the free
damped oscillator by means of the general solution of the corresponding Riccati
equation together with Witten's method of constructing the supersymmetric
partner operator. This procedure leads to one-parameter families of (transient)
modes for each of the three types of free damping, corresponding to a
particular type of %time-dependent angular frequency. %time-dependent,
antirestoring acceleration (adding up to the usual Hooke restoring
acceleration) of the form a(t)=\frac{2\gamma ^2}{(\gamma t+1)^{2}}\tilde{y},
where \gamma is the family parameter that has been chosen as the inverse of the
Riccati integration constant. In supersymmetric terms, they represent all those
one Riccati parameter damping modes having the same Newtonian free damping
partner mode",9707019v4
2000-08-22,Local and Fundamental Mode Coupler Damping of the Transverse Wakefield in RDDS1 Linacs,"In damping the wakefield generated by an electron beam traversing several
thousand X-band linacs in the NLC we utilise a Gaussian frequency distribution
of dipole modes to force the modes to deconstructively interfere, supplemented
with moderate damping achieved by coupling these modes to four attached
manifolds. Most of these modes are adequately damped by the manifolds. However,
the modes towards the high frequency end of the lower dipole band are not
adequately damped because the last few cells are, due to mechanical fabrication
requirements, not coupled to the manifolds. To mitigate this problem in the
present RDDS1 design, the output coupler for the accelerating mode has been
designed so as to also couple out those dipole modes which reach the output
coupler cell. In order to couple out both dipole mode polarizations, the output
coupler has four ports. We also report on the results of a study of the
benefits which can be achieved by supplementing manifold damping with local
damping for a limited number of cells at the downstream end of the structure.",0008211v1
2007-10-25,Damping of Condensate Oscillation of a Trapped Bose Gas in a One-Dimensional Optical Lattice at Finite Temperatures,"We study damping of a dipole oscillation in a Bose-Condensed gas in a
combined cigar-shaped harmonic trap and one-dimensional (1D) optical lattice
potential at finite temperatures. In order to include the effect of thermal
excitations in the radial direction, we derive a quasi-1D model of the
Gross-Pitaeavskii equation and the Bogoliubov equations. We use the Popov
approximation to calculate the temperature dependence of the condensate
fraction with varying lattice depth. We then calculate the Landau damping rate
of a dipole oscillation as a function of the lattice depth and temperature. The
damping rate increases with increasing lattice depth, which is consistent with
experimental observations. The magnitude of the damping rate is in reasonable
agreement with experimental data. We also find that the damping rate has a
strong temperature dependence, showing a sharp increase with increasing
temperature. Finally, we emphasize the importance of the radial thermal
excitations in both equilibrium properties and the Landau damping.",0710.4610v1
2008-01-03,Spin orbit precession damping in transition metal ferromagnets,"We provide a simple explanation, based on an effective field, for the
precession damping rate due to the spin-orbit interaction. Previous effective
field treatments of spin-orbit damping include only variations of the state
energies with respect to the magnetization direction, an effect referred to as
the breathing Fermi surface. Treating the interaction of the rotating spins
with the orbits as a perturbation, we include also changes in the state
populations in the effective field. In order to investigate the quantitative
differences between the damping rates of iron, cobalt, and nickel, we compute
the dependence of the damping rate on the density of states and the spin-orbit
parameter. There is a strong correlation between the density of states and the
damping rate. The intraband terms of the damping rate depend on the spin-orbit
parameter cubed while the interband terms are proportional to the spin-orbit
parameter squared. However, the spectrum of band gaps is also an important
quantity and does not appear to depend in a simple way on material parameters.",0801.0549v1
2009-02-03,Damping of filament thread oscillations: effect of the slow continuum,"Transverse oscillations of small amplitude are commonly seen in
high-resolution observations of filament threads, i.e. the fine-structures of
solar filaments/prominences, and are typically damped in a few periods. Kink
wave modes supported by the thread body offer a consistent explanation of these
observed oscillations. Among the proposed mechanisms to explain the kink mode
damping, resonant absorption in the Alfven continuum seems to be the most
efficient as it produces damping times of about 3 periods. However, for a
nonzero-beta plasma and typical prominence conditions, the kink mode is also
resonantly coupled to slow (or cusp) continuum modes, which could further
reduce the damping time. In this Letter, we explore for the first time both
analytically and numerically the effect of the slow continuum on the damping of
transverse thread oscillations. The thread model is composed of a homogeneous
and straight cylindrical plasma, an inhomogeneous transitional layer, and the
homogeneous coronal plasma. We find that the damping of the kink mode due to
the slow resonance is much less efficient than that due to the Alfven
resonance.",0902.0572v2
2010-11-23,Magnetohydrodynamic kink waves in two-dimensional non-uniform prominence threads,"We analyse the oscillatory properties of resonantly damped transverse kink
oscillations in two-dimensional prominence threads. The fine structures are
modelled as cylindrically symmetric magnetic flux tubes with a dense central
part with prominence plasma properties and an evacuated part, both surrounded
by coronal plasma. The equilibrium density is allowed to vary non-uniformly in
both the transverse and the longitudinal directions.We examine the influence of
longitudinal density structuring on periods, damping times, and damping rates
for transverse kink modes computed by numerically solving the linear resistive
magnetohydrodynamic (MHD) equations. The relevant parameters are the length of
the thread and the density in the evacuated part of the tube, two quantities
that are difficult to directly estimate from observations. We find that both of
them strongly influence the oscillatory periods and damping times, and to a
lesser extent the damping ratios. The analysis of the spatial distribution of
perturbations and of the energy flux into the resonances allows us to explain
the obtained damping times. Implications for prominence seismology, the physics
of resonantly damped kink modes in two-dimensional magnetic flux tubes, and the
heating of prominence plasmas are discussed.",1011.5175v2
2011-04-04,Plasmonic abilities of gold and silver spherical nanoantennas in terms of size dependent multipolar resonance frequencies and plasmon damping rates,"Absorbing and emitting optical properties of a spherical plasmonic
nanoantenna are described in terms of the size dependent resonance frequencies
and damping rates of the multipolar surface plasmons (SP). We provide the
plasmon size characteristics for gold and silver spherical particles up to the
large size retardation regime where the plasmon radiative damping is
significant. We underline the role of the radiation damping in comparison with
the energy dissipation damping in formation of receiving and transmitting
properties of a plasmonic particle. The size dependence of both: the multipolar
SP resonance frequencies and corresponding damping rates can be a convenient
tool in tailoring the characteristics of plasmonic nanoantennas for given
application. Such characteristics enable to control an operation frequency of a
plasmonic nanoantenna and to change the operation range from the spectrally
broad to spectrally narrow and vice versa. It is also possible to switch
between particle receiving (enhanced absorption) and emitting (enhanced
scattering) abilities. Changing the polarization geometry of observation it is
possible to effectively separate the dipole and the quadrupole plasmon
radiation from all the non-plasmonic contributions to the scattered light.
Keywords: surface plasmon (SP) resonance, plasmon damping rates, multipolar
plasmon",1104.0565v1
2012-07-27,The effect of non-uniform damping on flutter in axial flow and energy harvesting strategies,"The problem of energy harvesting from flutter instabilities in flexible
slender structures in axial flows is considered. In a recent study, we used a
reduced order theoretical model of such a system to demonstrate the feasibility
for harvesting energy from these structures. Following this preliminary study,
we now consider a continuous fluid-structure system. Energy harvesting is
modelled as strain-based damping and the slender structure under investigation
lies in a moderate fluid loading range, for which {the flexible structure} may
be destabilised by damping. The key goal of this work is to {analyse the effect
of damping distribution and intensity on the amount of energy harvested by the
system}. The numerical results {indeed} suggest that non-uniform damping
distributions may significantly improve the power harvesting capacity of the
system. For low damping levels, clustered dampers at the position of peak
curvature are shown to be optimal. Conversely for higher damping, harvesters
distributed over the whole structure are more effective.",1207.6484v1
2012-11-20,Damping rates of surface plasmons for particles of size from nano- to micrometers; reduction of the nonradiative decay,"Damping rates of multipolar, localized surface plasmons (SP) of gold and
silver nanospheres of radii up to $1000nm$ were found with the tools of
classical electrodynamics. The significant increase in damping rates followed
by noteworthy decrease for larger particles takes place along with substantial
red-shift of plasmon resonance frequencies as a function of particle size. We
also introduced interface damping into our modeling, which substantially
modifies the plasmon damping rates of smaller particles. We demonstrate
unexpected reduction of the multipolar SP damping rates in certain size ranges.
This effect can be explained by the suppression of the nonradiative decay
channel as a result of the lost competition with the radiative channel. We show
that experimental dipole damping rates [H. Baida, et al., Nano Lett. 9(10)
(2009) 3463, and C. S\""onnichsen, et al., Phys. Rev. Lett. 88 (2002) 077402],
and the resulting resonance quality factors can be described in a consistent
and straightforward way within our modeling extended to particle sizes still
unavailable experimentally.",1211.4781v1
2013-10-23,Landau damping in a collisionless dipolar Bose gas,"We present a theory for the Landau damping of low energy quasi-particles in a
collisionless, quasi-2D dipolar Bose gas and produce expressions for the
damping rate in uniform and non-uniform systems. Using simple energy-momentum
conservation arguments, we show that in the homogeneous system, the nature of
the low energy dispersion in a dipolar Bose gas severely inhibits Landau
damping of long wave-length excitations. For a gas with contact and dipolar
interactions, the damping rate for phonons tends to decrease with increasing
dipolar interactions; for strong dipole-dipole interactions, phonons are
virtually undamped over a broad range of temperature. The damping rate for
maxon-roton excitations is found to be significantly larger than the damping
rate for phonons.",1310.6386v1
2014-01-15,Damping of Terahertz Plasmons in Graphene Coupled with Surface Plasmons in Heavily-Doped Substrate,"Coupling of plasmons in graphene at terahert (THz) frequencies with surface
plasmons in a heavily-doped substrate is studied theoretically. We reveal that
a huge scattering rate may completely damp out the plasmons, so that proper
choices of material and geometrical parameters are essential to suppress the
coupling effect and to obtain the minimum damping rate in graphene. Even with
the doping concentration 10^{19} - 10^{20} cm^{-3} and the thickness of the
dielectric layer between graphene and the substrate 100 nm, which are typical
values in real graphene samples with a heavily-doped substrate, the increase in
the damping rate is not negligible in comparison with the
acoustic-phonon-limited damping rate. Dependence of the damping rate on
wavenumber, thicknesses of graphene-to-substrate and gate-to-graphene
separation, substrate doping concentration, and dielectric constants of
surrounding materials are investigated. It is shown that the damping rate can
be much reduced by the gate screening, which suppresses the field spread of the
graphene plasmons into the substrate.",1401.3396v1
2014-11-28,Non-equilibrium thermodynamics of damped Timoshenko and damped Bresse systems,"In this paper, we cast damped Timoshenko and damped Bresse systems into a
general framework for non-equilibrium thermodynamics, namely the GENERIC
(General Equation for Non-Equilibrium Reversible-Irreversible Coupling)
framework. The main ingredients of GENERIC consist of five building blocks: a
state space, a Poisson operator, a dissipative operator, an energy functional,
and an entropy functional. The GENERIC formulation of damped Timoshenko and
damped Bresse systems brings several benefits. First, it provides alternative
ways to derive thermodynamically consistent models of these systems by
construct- ing building blocks instead of invoking conservation laws and
constitutive relations. Second, it reveals clear physical and geometrical
structures of these systems, e.g., the role of the energy and the entropy as
the driving forces for the reversible and irreversible dynamics respectively.
Third, it allows us to introduce a new GENERIC model for damped Timoshenko
systems that is not existing in the literature.",1412.0038v2
2014-12-08,Bi-$\cal{PT}$ symmetry in nonlinearly damped dynamical systems and tailoring $\cal{PT}$ regions with position dependent loss-gain profiles,"We investigate the remarkable role of position dependent damping in
determining the parametric regions of symmetry breaking in nonlinear
$\cal{PT}$-symmetric systems. We illustrate the nature of $\cal{PT}$-symmetry
preservation and breaking with reference to a remarkable integrable scalar
nonlinear system. In the two dimensional cases of such position dependent
damped systems, we unveil the existence of a class of novel
bi-$\cal{PT}$-symmetric systems which have two fold $\cal{PT}$ symmetries. We
analyze the dynamics of these systems and show how symmetry breaking occurs,
that is whether the symmetry breaking of the two $\cal{PT}$ symmetries occurs
in pair or occurs one by one. The addition of linear damping in these
nonlinearly damped systems induces competition between the two types of
damping. This competition results in a $\cal{PT}$ phase transition in which the
$\cal{PT}$ symmetry is broken for lower loss/gain strength and is restored by
increasing the loss/gain strength. We also show that by properly designing the
form of the position dependent damping, we can tailor the $\cal{PT}$-symmetric
regions of the system.",1412.2574v3
2015-09-04,Damped transverse oscillations of interacting coronal loops,"Damped transverse oscillations of magnetic loops are routinely observed in
the solar corona. This phenomenon is interpreted as standing kink
magnetohydrodynamic waves, which are damped by resonant absorption owing to
plasma inhomogeneity across the magnetic field. The periods and damping times
of these oscillations can be used to probe the physical conditions of the
coronal medium. Some observations suggest that interaction between neighboring
oscillating loops in an active region may be important and can modify the
properties of the oscillations compared to those of an isolated loop. Here we
theoretically investigate resonantly damped transverse oscillations of
interacting non-uniform coronal loops. We provide a semi-analytic method, based
on the T-matrix theory of scattering, to compute the frequencies and damping
rates of collective oscillations of an arbitrary configuration of parallel
cylindrical loops. The effect of resonant damping is included in the T-matrix
scheme in the thin boundary approximation. Analytic and numerical results in
the specific case of two interacting loops are given as an application.",1509.01487v1
2015-09-14,Beliaev damping in quasi-2D dipolar condensates,"We study the effects of quasiparticle interactions in a quasi-two dimensional
(quasi-2D), zero-temperature Bose-Einstein condensate of dipolar atoms, which
can exhibit a roton-maxon feature in its quasiparticle spectrum. Our focus is
the Beliaev damping process, in which a quasiparticle collides with the
condensate and resonantly decays into a pair of quasiparticles. Remarkably, the
rate for this process exhibits a highly non-trivial dependence on the
quasiparticle momentum and the dipolar interaction strength. For weak
interactions, the low energy phonons experience no damping, and the higher
energy quasiparticles undergo anomalously weak damping. In contrast, the
Beliaev damping rates become anomalously large for stronger dipolar
interactions, as rotons become energetically accessible as final states.
Further, we find a qualitative anisotropy in the damping rates when the dipoles
are tilted off the axis of symmetry. Our study reveals the unconventional
nature of Beliaev damping in dipolar condensates, and has important
implications for ongoing studies of equilibrium and non-equilibrium dynamics in
these systems.",1509.04217v1
2016-10-10,A Five-Freedom Active Damping and Alignment Device Used in the Joule Balance,"Damping devices are necessary for suppressing the undesired coil motions in
the watt/joule balance. In this paper, an active electromagnetic damping
device, located outside the main magnet, is introduced in the joule balance
project. The presented damping device can be used in both dynamic and static
measurement modes. With the feedback from a detection system, five degrees of
freedom of the coil, i.e. the horizontal displacement $x$, $y$ and the rotation
angles $\theta_x$, $\theta_y$, $\theta_z$, can be controlled by the active
damping device. Hence, two functions, i.e. suppressing the undesired coil
motions and reducing the misalignment error, can be realized with this active
damping device. The principle, construction and performance of the proposed
active damping device are presented.",1610.02799v1
2016-10-01,The destabilizing effect of external damping: Singular flutter boundary for the Pfluger column with vanishing external dissipation,"Elastic structures loaded by nonconservative positional forces are prone to
instabilities induced by dissipation: it is well-known in fact that internal
viscous damping destabilizes the marginally stable Ziegler's pendulum and
Pfluger column (of which the Beck's column is a special case), two structures
loaded by a tangential follower force. The result is the so-called
'destabilization paradox', where the critical force for flutter instability
decreases by an order of magnitude when the coefficient of internal damping
becomes infinitesimally small. Until now external damping, such as that related
to air drag, is believed to provide only a stabilizing effect, as one would
intuitively expect. Contrary to this belief, it will be shown that the effect
of external damping is qualitatively the same as the effect of internal
damping, yielding a pronounced destabilization paradox. Previous results
relative to destabilization by external damping of the Ziegler's and Pfluger's
elastic structures are corrected in a definitive way leading to a new
understanding of the destabilizating role played by viscous terms.",1611.03886v1
2018-05-04,Effective damping enhancement in noncollinear spin structures,"Damping mechanisms in magnetic systems determine the lifetime, diffusion and
transport properties of magnons, domain walls, magnetic vortices, and
skyrmions. Based on the phenomenological Landau-Lifshitz-Gilbert equation, here
the effective damping parameter in noncollinear magnetic systems is determined
describing the linewidth in resonance experiments or the decay parameter in
time-resolved measurements. It is shown how the effective damping can be
calculated from the elliptic polarization of magnons, arising due to the
noncollinear spin arrangement. It is concluded that the effective damping is
larger than the Gilbert damping, and it may significantly differ between
excitation modes. Numerical results for the effective damping are presented for
the localized magnons in isolated skyrmions, with parameters based on the
Pd/Fe/Ir(111) model-type system.",1805.01815v2
2018-05-16,Stabilization rates for the damped wave equation with Hölder-regular damping,"We study the decay rate of the energy of solutions to the damped wave
equation in a setup where the geometric control condition is violated. We
consider damping coefficients which are $0$ on a strip and vanish like
polynomials, $x^{\beta}$. We prove that the semigroup cannot be stable at rate
faster than $1/t^{(\beta+2)/(\beta+3)}$ by producing quasimodes of the
associated stationary damped wave equation. We also prove that the semigroup is
stable at rate at least as fast as $1/t^{(\beta+2)/(\beta+4)}$. These two
results establish an explicit relation between the rate of vanishing of the
damping and rate of decay of solutions. Our result partially generalizes a
decay result of Nonnemacher in which the damping is an indicator function on a
strip.",1805.06535v3
2011-11-16,Three-player quantum Kolkata restaurant problem under decoherence,"Effect of quantum decoherence in a three-player quantum Kolkata restaurant
problem is investigated using tripartite entangled qutrit states. Amplitude
damping, depolarizing, phase damping, trit-phase flip and phase flip channels
are considered to analyze the behaviour of players payoffs. It is seen that
Alice's payoff is heavily influenced by the amplitude damping channel as
compared to the depolarizing and flipping channels. However, for higher level
of decoherence, Alice's payoff is strongly affected by depolarizing noise.
Whereas the behaviour of phase damping channel is symmetrical around 50 %
decoherence. It is also seen that for maximum decoherence (p=1), the influence
of amplitude damping channel dominates over depolarizing and flipping channels.
Whereas, phase damping channel has no effect on the Alice's payoff. Therefore,
the problem becomes noiseless one at maximum decoherence in case of phase
damping channel. Furthermore, the Nash equilibrium of the problem does not
change under decoherence.",1111.3913v2
2015-12-08,Thermal energies of classical and quantum damped oscillators coupled to reservoirs,"We consider the global thermal state of classical and quantum harmonic
oscillators that interact with a reservoir. Ohmic damping of the oscillator can
be exactly treated with a 1D scalar field reservoir, whereas general non-Ohmic
damping is conveniently treated with a continuum reservoir of harmonic
oscillators. Using the diagonalized Hamiltonian of the total system, we
calculate a number of thermodynamic quantities for the damped oscillator: the
mean force internal energy, mean force free energy, and another internal energy
based on the free-oscillator Hamiltonian. The classical mean force energy is
equal to that of a free oscillator, for both Ohmic and non-Ohmic damping and no
matter how strong the coupling to the reservoir. In contrast, the quantum mean
force energy depends on the details of the damping and diverges for strictly
Ohmic damping. These results give additional insight into the steady-state
thermodynamics of open systems with arbitrarily strong coupling to a reservoir,
complementing results for energies derived within dynamical approaches (e.g.
master equations) in the weak-coupling regime.",1512.02551v2
2016-05-17,Simultaneous Identification of Damping Coefficient and Initial Value in PDEs from boundary measurement,"In this paper, the simultaneous identification of damping or anti-damping
coefficient and initial value for some PDEs is considered. An identification
algorithm is proposed based on the fact that the output of system happens to be
decomposed into a product of an exponential function and a periodic function.
The former contains information of the damping coefficient, while the latter
does not. The convergence and error analysis are also developed. Three
examples, namely an anti-stable wave equation with boundary anti-damping, the
Schr\""odinger equation with internal anti-damping, and two connected strings
with middle joint anti-damping, are investigated and demonstrated by numerical
simulations to show the effectiveness of the proposed algorithm.",1605.05063v1
2016-08-30,Optimal damping ratios of multi-axial perfectly matched layers for elastic-wave modeling in general anisotropic media,"The conventional Perfectly Matched Layer (PML) is unstable for certain kinds
of anisotropic media. This instability is intrinsic and independent of PML
formulation or implementation. The Multi-axial PML (MPML) removes such
instability using a nonzero damping coefficient in the direction parallel with
the interface between a PML and the investigated domain. The damping ratio of
MPML is the ratio between the damping coefficients along the directions
parallel with and perpendicular to the interface between a PML and the
investigated domain. No quantitative approach is available for obtaining these
damping ratios for general anisotropic media. We develop a quantitative
approach to determining optimal damping ratios to not only stabilize PMLs, but
also minimize the artificial reflections from MPMLs. Numerical tests based on
finite-difference method show that our new method can effectively provide a set
of optimal MPML damping ratios for elastic-wave propagation in 2D and 3D
general anisotropic media.",1608.08326v3
2017-10-10,A four-field gyrofluid model with neoclassical effects for the study of the rotation velocity of magnetic islands in tokamaks,"A four-field system of equations which includes the neoclassical flow damping
effects and the lowest-order finite-Larmor-radius (FLR) corrections is deduced
from a system of gyrofluid equations. The FLR corrections to the poloidal flow
damping are calculated by solving a simplified version of the gyrokinetic
equation. This system of equations is applied to the study of a chain of freely
rotating magnetic islands in a tokamak, resulting from the nonlinear evolution
of a resistive tearing mode, to determine the islands rotation velocity
consistently with the fields radial profiles close to the resonant surface. The
island rotation velocity is determined by imposing the torque-balance
condition. The equations thus deduced are applied to the study of two different
collisional regimes, namely the weak-damping regime and the intermediate
damping regime. The equations reduce, in the weak damping regime, to a form
already obtained in previous works, while an additional term, containing the
lowest order FLR corrections to the poloidal flow damping, appears in the
intermediate damping regime. The numerical integration of the final system of
equations permits to determine the dependence of the island rotation velocity
on the plasma collisionality and the islands width compared to the ion Larmor
radius.",1710.03585v1
2017-10-13,Mode-Dependent Damping in Metallic Antiferromagnets Due to Inter-Sublattice Spin Pumping,"Damping in magnetization dynamics characterizes the dissipation of magnetic
energy and is essential for improving the performance of spintronics-based
devices. While the damping of ferromagnets has been well studied and can be
artificially controlled in practice, the damping parameters of
antiferromagnetic materials are nevertheless little known for their physical
mechanisms or numerical values. Here we calculate the damping parameters in
antiferromagnetic dynamics using the generalized scattering theory of
magnetization dissipation combined with the first-principles transport
computation. For the PtMn, IrMn, PdMn and FeMn metallic antiferromagnets, the
damping coefficient associated with the motion of magnetization ($\alpha_m$) is
one to three orders of magnitude larger than the other damping coefficient
associated with the variation of the N\'eel order ($\alpha_n$), in sharp
contrast to the assumptions made in the literature.",1710.04766v1
2017-12-04,Resonance oscillation of a damped driven simple pendulum,"The resonance characteristics of a driven damped harmonic oscillator are well
known. Unlike harmonic oscillators which are guided by parabolic potentials, a
simple pendulum oscillates under sinusoidal potentials. The problem of an
undamped pendulum has been investigated to a great extent. However, the
resonance characteristics of a driven damped pendulum have not been re- ported
so far due to the difficulty in solving the problem analytically. In the
present work we report the resonance characteristics of a driven damped
pendulum calculated numerically. The results are compared with the resonance
characteristics of a damped driven harmonic oscillator. The work can be of
pedagogic interest too as it reveals the richness of driven damped motion of a
simple pendulum in comparison to and how strikingly it differs from the motion
of a driven damped harmonic oscillator. We confine our work only to the
nonchaotic regime of pendulum motion.",1712.01032v1
2018-01-17,On Global Existence and Blow-up for Damped Stochastic Nonlinear Schrödinger Equation,"In this paper, we consider the well-posedness of the weakly damped stochastic
nonlinear Schr\""odinger(NLS) equation driven by multiplicative noise. First, we
show the global existence of the unique solution for the damped stochastic NLS
equation in critical case. Meanwhile, the exponential integrability of the
solution is proved, which implies the continuous dependence on the initial
data. Then, we analyze the effect of the damped term and noise on the blow-up
phenomenon. By modifying the associated energy, momentum and variance identity,
we deduce a sharp blow-up condition for damped stochastic NLS equation in
supercritical case. Moreover, we show that when the damped effect is large
enough, the damped effect can prevent the blow-up of the solution with high
probability.",1801.05630v1
2019-10-31,Gyrokinetic investigation of the damping channels of Alfvén modes in ASDEX Upgrade,"The linear destabilization and nonlinear saturation of energetic-particle
driven Alfv\'enic instabilities in tokamaks strongly depend on the damping
channels. In this work, the collisionless damping mechanisms of Alfv\'enic
modes are investigated within a gyrokinetic framework, by means of global
simulations with the particle-in-cell code ORB5, and compared with the
eigenvalue code LIGKA and reduced models. In particular, the continuum damping
and the Landau damping (of ions and electrons) are considered. The electron
Landau damping is found to be dominant on the ion Landau damping for
experimentally relevant cases. As an application, the linear and nonlinear
dynamics of toroidicity induced Alfv\'en eigenmodes and energetic-particle
driven modes in ASDEX Upgrade is investigated theoretically and compared with
experimental measurements.",1910.14489v1
2020-12-27,Quantum speed limit time in relativistic frame,"We investigate the roles of the relativistic effect on the speed of evolution
of a quantum system coupled with amplitude damping channels. We find that the
relativistic effect speed-up the quantum evolution to a uniform evolution speed
of open quantum systems for the damping parameter $p_{\tau}\lesssim
p_{\tau_{c0}}.$ Moreover, we point out a non-monotonic behavior of the quantum
speed limit time (QSLT) with acceleration in the damping limit
$p_{\tau_{c0}}\lesssim p_{\tau}\lesssim p_{\tau_{c1}},$ where the relativistic
effect first speed-up and then slow down the quantum evolution process of the
damped system. For the damping strength $p_{\tau_{c1}}\lesssim p_{\tau}$, we
observe a monotonic increasing behavior of QSLT, leads to slow down the quantum
evolution of the damped system. In addition, we examine the roles of the
relativistic effect on the speed limit time for a system coupled with the phase
damping channels.",2012.13859v2
2021-01-07,Mechanisms behind large Gilbert damping anisotropies,"A method with which to calculate the Gilbert damping parameter from a
real-space electronic structure method is reported here. The anisotropy of the
Gilbert damping with respect to the magnetic moment direction and local
chemical environment is calculated for bulk and surfaces of Fe$_{50}$Co$_{50}$
alloys from first principles electronic structure in a real space formulation.
The size of the damping anisotropy for Fe$_{50}$Co$_{50}$ alloys is
demonstrated to be significant. Depending on details of the simulations, it
reaches a maximum-minimum damping ratio as high as 200%. Several microscopic
origins of the strongly enhanced Gilbert damping anisotropy have been examined,
where in particular interface/surface effects stand out, as do local
distortions of the crystal structure. Although theory does not reproduce the
experimentally reported high ratio of 400% [Phys. Rev. Lett. 122, 117203
(2019)], it nevertheless identifies microscopic mechanisms that can lead to
huge damping anisotropies.",2101.02794v2
2018-03-29,Giant resonant nonlinear damping in nanoscale ferromagnets,"Magnetic damping is a key metric for emerging technologies based on magnetic
nanoparticles, such as spin torque memory and high-resolution biomagnetic
imaging. Despite its importance, understanding of magnetic dissipation in
nanoscale ferromagnets remains elusive, and the damping is often treated as a
phenomenological constant. Here we report the discovery of a giant
frequency-dependent nonlinear damping that strongly alters the response of a
nanoscale ferromagnet to spin torque and microwave magnetic field. This novel
damping mechanism originates from three-magnon scattering that is strongly
enhanced by geometric confinement of magnons in the nanomagnet. We show that
the giant nonlinear damping can invert the effect of spin torque on a
nanomagnet leading to a surprising current-induced enhancement of damping by an
antidamping torque. Our work advances understanding of magnetic dynamics in
nanoscale ferromagnets and spin torque devices.",1803.10925v1
2018-08-20,Gilbert damping of [Co/Pd]n/Py multilayer thin films,"Understanding the Gilbert damping in exchange-coupled multilayer materials is
particularly important to develop future fast switching spintronics devices.
Here, we report an experimental investigation of temperature-dependent Gilbert
damping in [Co/Pd]n/Py multilayer films of varying the number of Co/Pd
repetitions by ferromagnetic resonance. The results demonstrate that three
independent contributions to the Gilbert damping are identified, namely the
intrinsic Gilbert damping, the inhomogeneous linewidth broadening and the
two-magnon scattering contribution. Of particular interest, the two-magnon
scattering intensity increases as the enlargement of number repetitions of
Co/Pd due to the larger pinning effect at the interface between Py and the
Co/Pd layers. The Gilbert damping increases monotonically as the temperature
decreases from 300K to 50K. Our findings open the door to comprehend the
physical origin of the Gilbert damping in ultrathin exchange-coupled multilayer
films.",1808.06515v2
2019-03-01,Comprehensive Study of Neutrino-Dark Matter Mixed Damping,"Mixed damping is a physical effect that occurs when a heavy species is
coupled to a relativistic fluid which is itself free streaming. As a cross-case
between collisional damping and free-streaming, it is crucial in the context of
neutrino-dark matter interactions. In this work, we establish the parameter
space relevant for mixed damping, and we derive an analytical approximation for
the evolution of dark matter perturbations in the mixed damping regime to
illustrate the physical processes responsible for the suppression of
cosmological perturbations. Although extended Boltzmann codes implementing
neutrino-dark matter scattering terms automatically include mixed damping, this
effect has not been systematically studied. In order to obtain reliable
numerical results, it is mandatory to reconsider several aspects of
neutrino-dark matter interactions, such as the initial conditions, the
ultra-relativistic fluid approximation and high order multiple moments in the
neutrino distribution. Such a precise treatment ensures the correct assessment
of the relevance of mixed damping in neutrino-dark matter interactions.",1903.00540v2
2019-08-04,Efficient spin excitation via ultrafast damping-like torques in antiferromagnets,"Damping effects form the core of many emerging concepts for high-speed
spintronic applications. Important characteristics such as device switching
times and magnetic domain-wall velocities depend critically on the damping
rate. While the implications of spin damping for relaxation processes are
intensively studied, damping effects during impulsive spin excitations are
assumed to be negligible because of the shortness of the excitation process.
Herein, we show that, unlike in ferromagnets, ultrafast damping plays a crucial
role in antiferromagnets because of their strongly elliptical spin precession.
In time-resolved measurements, we find that ultrafast damping results in an
immediate spin canting along the short precession axis. The interplay between
antiferromagnetic exchange and magnetic anisotropy amplifies this canting by
several orders of magnitude towards large-amplitude modulations of the
antiferromagnetic order parameter. This leverage effect discloses a highly
efficient route towards the ultrafast manipulation of magnetism in
antiferromagnetic spintronics.",1908.01359v3
2020-03-13,Anharmonic phonon damping enhances the $T_c$ of BCS-type superconductors,"A theory of superconductivity is presented where the effect of anharmonicity,
as entailed in the acoustic, or optical, phonon damping, is explicitly
considered in the pairing mechanism. The gap equation is solved including
diffusive Akhiezer damping for longitudinal acoustic phonons or Klemens damping
for optical phonons, with a damping coefficient which, in either case, can be
directly related to the Gruneisen parameter and hence to the anharmonic
coefficients in the interatomic potential. The results show that the increase
of anharmonicity has a strikingly non-monotonic effect on the critical
temperature $T_{c}$. The optimal damping coefficient yielding maximum $T_c$ is
set by the velocity of the bosonic mediator. This theory may open up
unprecedented opportunities for material design where $T_{c}$ may be tuned via
the anharmonicity of the interatomic potential, and presents implications for
the superconductivity in the recently discovered hydrides, where anharmonicity
is very strong and for which the anharmonic damping is especially relevant.",2003.06220v2
2020-03-29,Stability results for an elastic-viscoelastic waves interaction systems with localized Kelvin-Voigt damping and with an internal or boundary time delay,"We investigate the stability of a one-dimensional wave equation with non
smooth localized internal viscoelastic damping of Kelvin-Voigt type and with
boundary or localized internal delay feedback. The main novelty in this paper
is that the Kelvin-Voigt and the delay damping are both localized via non
smooth coefficients. In the case that the Kelvin-Voigt damping is localized
faraway from the tip and the wave is subjected to a locally distributed
internal or boundary delay feedback, we prove that the energy of the system
decays polynomially of type t^{-4}. However, an exponential decay of the energy
of the system is established provided that the Kelvin-Voigt damping is
localized near a part of the boundary and a time delay damping acts on the
second boundary. While, when the Kelvin-Voigt and the internal delay damping
are both localized via non smooth coefficients near the tip, the energy of the
system decays polynomially of type t^{-4}. Frequency domain arguments combined
with piecewise multiplier techniques are employed.",2003.12967v1
2020-09-16,Fast convex optimization via inertial dynamics combining viscous and Hessian-driven damping with time rescaling,"In a Hilbert setting, we develop fast methods for convex unconstrained
optimization. We rely on the asymptotic behavior of an inertial system
combining geometric damping with temporal scaling. The convex function to
minimize enters the dynamic via its gradient. The dynamic includes three
coefficients varying with time, one is a viscous damping coefficient, the
second is attached to the Hessian-driven damping, the third is a time scaling
coefficient. We study the convergence rate of the values under general
conditions involving the damping and the time scale coefficients. The obtained
results are based on a new Lyapunov analysis and they encompass known results
on the subject. We pay particular attention to the case of an asymptotically
vanishing viscous damping, which is directly related to the accelerated
gradient method of Nesterov. The Hessian-driven damping significantly reduces
the oscillatory aspects. As a main result, we obtain an exponential rate of
convergence of values without assuming the strong convexity of the objective
function. The temporal discretization of these dynamics opens the gate to a
large class of inertial optimization algorithms.",2009.07620v1
2021-06-23,Regularization of central forces with damping in two and three-dimensions,"Regularization of damped motion under central forces in two and
three-dimensions are investigated and equivalent, undamped systems are
obtained. The dynamics of a particle moving in $\frac{1}{r}$ potential and
subjected to a damping force is shown to be regularized a la Levi-Civita. We
then generalize this regularization mapping to the case of damped motion in the
potential $r^{-\frac{2N}{N+1}}$. Further equation of motion of a damped Kepler
motion in 3-dimensions is mapped to an oscillator with inverted sextic
potential and couplings, in 4-dimensions using Kustaanheimo-Stiefel
regularization method. It is shown that the strength of the sextic potential is
given by the damping co-efficient of the Kepler motion. Using homogeneous
Hamiltonian formalism, we establish the mapping between the Hamiltonian of
these two models. Both in 2 and 3-dimensions, we show that the regularized
equation is non-linear, in contrast to undamped cases. Mapping of a particle
moving in a harmonic potential subjected to damping to an undamped system with
shifted frequency is then derived using Bohlin-Sudman transformation.",2106.12134v1
2021-07-06,Theory of vibrators with variable-order fractional forces,"In this paper, we present a theory of six classes of vibrators with
variable-order fractional forces of inertia, damping, and restoration. The
novelty and contributions of the present theory are reflected in six aspects.
1) Equivalent motion equations of those variable-order fractional vibrators are
proposed. 2) The analytical expressions of the effective mass, damping, and
stiffness of those variable-order fractional vibrators are presented. 3) The
asymptotic properties of the effective mass, damping, and stiffness of a class
of variable-order fractional vibrators are given. 4) The restricted effective
parameters (damping ratio, damping free natural frequency, damped natural
frequency, frequency ratio) of the variable-order fractional vibrators are put
forward. 5) We bring forward the analytical representations of the free
responses, the impulse responses, and the frequency transfer functions of those
variable-order fractional vibrators. 6) We propose a solution to an open
problem of how to mathematically explain the Rayleigh damping assumption based
on the present theory of variable-order fractional vibrations.",2107.02340v2
2021-08-15,Exponential stability of a damped beam-string-beam transmission problem,"We consider a beam-string-beam transmission problem, where two structurally
damped or undamped beams are coupled with a frictionally damped string by
transmission conditions. We show that for this type of structure, the
dissipation produced by the frictional part is strong enough to produce
exponential decay of the solution no matter how small is its size: for the
exponential stability in the damped-damped-damped situation we use energy
method and in the undamped-damped-undamped situation we use a frequency domain
method from the semigroups theory, which combines a contradiction argument with
the multiplier technique to carry out a special analysis for the resolvent.
Additionally, we show that the solution first defined by the weak formulation,
in fact, has higher Sobolev space regularity.",2108.06749v1
2021-09-10,Fourth-order dynamics of the damped harmonic oscillator,"It is shown that the classical damped harmonic oscillator belongs to the
family of fourth-order Pais-Uhlenbeck oscillators. It follows that the
solutions to the damped harmonic oscillator equation make the Pais-Uhlenbeck
action stationary. Two systematic approaches are given for deriving the
Pais-Uhlenbeck action from the damped harmonic oscillator equation, and it may
be possible to use these methods to identify stationary action principles for
other dissipative systems which do not conform to Hamilton's principle. It is
also shown that for every damped harmonic oscillator $x$, there exists a
two-parameter family of dual oscillators $y$ satisfying the Pais-Uhlenbeck
equation. The damped harmonic oscillator and any of its duals can be
interpreted as a system of two coupled oscillators with atypical spring
stiffnesses (not necessarily positive and real-valued). For overdamped systems,
the resulting coupled oscillators should be physically achievable and may have
engineering applications. Finally, a new physical interpretation is given for
the optimal damping ratio $\zeta=1/\sqrt{2}$ in control theory.",2109.06034v1
2022-01-13,Damping of Alfvén waves in MHD turbulence and implications for cosmic ray streaming instability and galactic winds,"Alfv\'{e}nic component of MHD turbulence damps Alfv\'{e}nic waves. The
consequences of this effect are important for many processes, from cosmic ray
(CR) propagation to launching outflows and winds in galaxies and other
magnetized systems. We discuss the differences in the damping of the streaming
instability by turbulence and the damping of a plane parallel wave. The former
takes place in the system of reference aligned with the local direction of
magnetic field along which CRs stream. The latter is in the reference frame of
the mean magnetic field and traditionally considered in plasma studies. We also
compare the turbulent damping of streaming instability with ion-neutral
collisional damping, which becomes the dominant damping effect at a
sufficiently low ionization fraction. Numerical testing and astrophysical
implications are also discussed.",2201.05168v1
2022-03-14,Investigation of nonlinear squeeze-film damping involving rarefied gas effect in micro-electro-mechanical-systems,"In this paper, the nonlinear squeeze-film damping (SFD) involving rarefied
gas effect in the micro-electro-mechanical-systems (MEMS) is investigated.
Considering the motion of structures (beam, cantilever, and membrane) in MEMS,
the dynamic response of structure will be influenced largely by the
squeeze-film damping. In the traditional model, a viscous damping assumption
that damping force is linear with moving velocity is used. As the nonlinear
damping phenomenon is observed for a micro-structure oscillating with a
high-velocity, this assumption is invalid and will generates error result for
predicting the response of micro-structure. In addition, due to the small size
of device and the low pressure of encapsulation, the gas in MEMS usually is
rarefied gas. Therefore, to correctly predict the damping force, the rarefied
gas effect must be considered. To study the nonlinear SFD phenomenon involving
the rarefied gas effect, a kinetic method, namely discrete unified gas kinetic
scheme (DUGKS), is introduced. And based on DUGKS, two solving methods, a
traditional decoupled method (Eulerian scheme) and a coupled framework
(arbitrary Lagrangian-Eulerian scheme), are adopted. With these two methods,
two basic motion forms, linear (perpendicular) and tilting motions of a rigid
micro-beam, are studied with forced and free oscillations.",2203.06902v1
2022-05-21,Noether symmetries and first integrals of damped harmonic oscillator,"Noether theorem establishes an interesting connection between symmetries of
the action integral and conservation laws of a dynamical system. The aim of the
present work is to classify the damped harmonic oscillator problem with respect
to Noether symmetries and to construct corresponding conservation laws for all
over-damped, under damped and critical damped cases. For each case we obtain
maximum five linearly independent group generators which provide related five
conserved quantities. Remarkably, after obtaining complete set of invariant
quantities we obtain analytical solutions for each case. In the current work,
we also introduce a new Lagrangian for the damped harmonic oscillator. Though
the form of this new Lagrangian and presented by Bateman are completely
different, yet it generates same set of Noether symmetries and conserved
quantities. So, this new form of Lagrangian we are presenting here may be
seriously interesting for the physicists. Moreover, we also find the Lie
algebras of Noether symmetries and point out some interesting aspects of
results related to Noether symmetries and first integrals of damped harmonic
oscillator which perhaps not reported in the earlier studies.",2205.10525v1
2023-01-31,The emergence of soft-glassy mechanics in simulated foams,"Several seemingly different soft materials, including foams, cells, and many
complex fluids, exhibit remarkably similar rheological properties and
microscopic dynamics, termed soft glassy mechanics. Here, we show that such
behavior emerges from a simple model of a damped ripening foam, for
sufficiently weak damping. In particular, we observe intermittent avalanchey
dynamics, bubble super-diffusion, and power-law rheology that vary as the
damping factor is changed. In the limit of weak damping, the dynamics are
determined by the tortuous low-lying portions of the energy landscape, as
described in a recent study. For strong damping the viscous stresses cause the
system configuration to evolve along higher energy paths, washing out
small-scale tortuosity and producing motion with an increasingly ballistic
character. Using a microrheological approach, the linear viscoelastic response
of the model can be efficiently calculated. This resembles the power-law
rheology expected for soft glassy mechanics, but unexpectedly, is only weakly
sensitive to the damping parameter. Lastly, we study the reported memory effect
in foams after large perturbations and find that the timescale of the memory
goes to zero as the damping parameter vanishes, suggesting that the effect is
due to viscous stress relaxation rather than slow structural changes stabilized
by the energy landscape.",2301.13400v1
2023-02-13,Thickness and temperature dependent damping in La$_{0.67}$Sr$_{0.33}$MnO$_{3}$ epitaxial films,"The damping of La0.67Sr0.33MnO3 (LSMO) epitaxial films as a function of
thickness at different temperatures was studied. The competition between two
scattering types (\r{ho}-like and {\sigma}-like) with entirely distinct
thickness and temperature dependencies resulted in complicated damping
behavior. The behavior of {\sigma}-like damping in LSMO films is consistent
with the behavior in magnetic metal films. However, because \r{ho}-like damping
is sensitive to the fine electron structure near the Fermi surface, the
distortion of the oxygen octahedra controlled by the film thickness is an
important factor in controlling the damping. Our study demonstrates that the
complexity of damping in LSMO epitaxial films is a consequence of
strong-correlation effects, which are characteristic of complex
transition-metal oxides.",2302.06099v3
2023-09-15,On the formation of singularities for the slightly supercritical NLS equation with nonlinear damping,"We consider the focusing, mass-supercritical NLS equation augmented with a
nonlinear damping term. We provide sufficient conditions on the nonlinearity
exponents and damping coefficients for finite-time blow-up. In particular,
singularities are formed for focusing and dissipative nonlinearities of the
same power, provided that the damping coefficient is sufficiently small. Our
result thus rigorously proves the non-regularizing effect of nonlinear damping
in the mass-supercritical case, which was suggested by previous numerical and
formal results.
  We show that, under our assumption, the damping term may be controlled in
such a way that the self-similar blow-up structure for the focusing NLS is
approximately retained even within the dissipative evolution. The nonlinear
damping contributes as a forcing term in the equation for the perturbation
around the self-similar profile, that may produce a growth over finite time
intervals. We estimate the error terms through a modulation analysis and a
careful control of the time evolution of total momentum and energy functionals.",2309.08281v1
2007-02-14,Lorentz-violating electrodynamics and the cosmic microwave background,"Possible Lorentz-violating effects in the cosmic microwave background are
studied. We provide a systematic classification of renormalizable and
nonrenormalizable operators for Lorentz violation in electrodynamics and use
polarimetric observations to search for the associated violations.",0702379v2
1998-10-04,Testing a CPT- and Lorentz-Violating Extension of the Standard Model,"A brief summary is given of recent developments concerning a
Lorentz-violating extension of the standard model and its implications for
experiments testing Lorentz and CPT symmetry.",9810239v1
1999-04-27,Theory and Tests of CPT and Lorentz Violation,"A general Lorentz-violating extension of the standard model of particle
physics, allowing for both CPT-even and CPT-odd effects, is described. Some of
its theoretical aspects and experimental implications are summarized.",9904467v1
1999-12-29,Lorentz and CPT tests with spin-polarized solids,"Experiments using macroscopic samples of spin-polarized matter offer
exceptional sensitivity to Lorentz and CPT violation in the electron sector.
Data from existing experiments with a spin-polarized torsion pendulum provide
sensitivity in this sector rivaling that of all other existing experiments and
could reveal spontaneous violation of Lorentz symmetry at the Planck scale.",9912542v1
2000-11-21,Lorentz and CPT Tests in QED,"A theoretical framework extending QED in the context of the standard model is
used to analyze a variety of Lorentz and CPT tests in atomic systems.
Experimental signatures of possible Lorentz and CPT violation in these systems
are investigated, and bounds are discussed.",0011272v1
2001-10-13,CPT and Lorentz Violations in Neutrino Oscillations,"Tests of Lorentz invariance violation and CPT Violation in neutrino
oscillations are discussed. The sensitivity of current and future experiments
is presented.",0110175v2
2001-11-02,Cosmological Constraints on Lorentz Violation in Electrodynamics,"Infrared, optical, and ultraviolet spectropolarimetry of cosmological sources
is used to constrain the pure electromagnetic sector of a general
Lorentz-violating standard-model extension. The coefficients for Lorentz
violation are bounded to less than 3x10^{-32}.",0111026v1
2001-11-24,CPT and Lorentz Tests with Clocks in Space,"Space-based clock-comparison experiments can provide Planck-scale sensitivity
to many parameters for Lorentz and CPT violation that are difficult to measure
on Earth. The principal advantages are a reduced timescale for data collection,
reduced suppression for certain effects, and access to certain parameters not
possible with Earth-based experiments.",0111320v2
2001-12-23,Electromagnetic Tests of Lorentz and CPT Symmetry,"A review is presented of some recent Lorentz and CPT tests in atomic and
particle systems where the predominant interactions are described by quantum
electrodynamics. A theoretical framework extending QED in the context of the
standard model is used to analyze these systems. Experimental signatures of
possible Lorentz and CPT violation are investigated, and bounds are discussed.",0112318v1
2002-12-11,Astrophysical Tests of Lorentz Symmetry in Electrodynamics,"In this talk presented at the Fourth International Workshop on New Worlds in
Astroparticle Physics, I discuss recent constraints on Lorentz violation in
electrodynamics. The observed absence of birefringence of light that has
propagated over cosmological distances bounds some coefficients for Lorentz
violation to 2 x 10^{-32}.",0212157v1
2003-08-20,Apparent Lorentz violation through spacetime-varying couplings,"In this talk, we explore the relation between smoothly varying couplings and
Lorentz violation. Within the context of a supergravity model, we present an
explicit mechanism that causes the effective fine-structure parameter and the
effective electromagnetic $\theta$ angle to acquire related spacetime
dependences. We argue that this leads to potentially observable Lorentz
violation and discuss some implications for the Standard-Model Extension.",0308208v1
2003-12-05,Fundamental physics and Lorentz violation,"The violation of Lorentz symmetry can arise in a variety of approaches to
fundamental physics. For the description of the associated low-energy effects,
a dynamical framework known as the Standard-Model Extension has been developed.
This talk gives a brief review of the topic focusing on Lorentz violation
through varying couplings.",0312093v1
2004-07-21,Lorentz-Violating Electrostatics and Magnetostatics,"The static limit of Lorentz-violating electrodynamics in vacuum and in media
is investigated. Features of the general solutions include the need for
unconventional boundary conditions and the mixing of electrostatic and
magnetostatic effects. Explicit solutions are provided for some simple cases.
Electromagnetostatics experiments show promise for improving existing
sensitivities to parity-odd coefficients for Lorentz violation in the photon
sector.",0407252v1
2005-03-14,On photon splitting in theories with Lorentz invariance violation,"In a model with Lorentz invariance violation implemented through modified
dispersion relations, we estimate the rate for the decay process gamma -> 3
gamma and find that it provides a relevant bound on Lorentz invariance
violation.",0503130v2
2005-11-22,Tests of Lorentz Symmetry with Penning Traps and Antihydrogen,"Possibilities for testing Lorentz symmetry using precision experiments with
antiprotons in Penning traps and with antihydrogen spectroscopy are reviewed.
Estimates of bounds on relevant coefficients for Lorentz violation in the
Standard-Model Extension (SME) are considered.",0511262v1
2001-10-23,"Dark Matter, Quantum Gravity, Vacuum Energy, and Lorentz Invariance","We discuss the problems of dark matter, quantum gravity, and vacuum energy
within the context of a theory for which Lorentz invariance is not postulated,
but instead emerges as a natural consequence in the physical regimes where it
has been tested.",0110208v1
2002-03-05,Propagator for a spin 1/2 particle in terms of the unitary representations of the Lorentz group,"In this paper we extend our previous result on the description of the partcle
motion in a generalized Heisenberg picture to a relativistic fermion. The
operators of the Lorentz algebra in this picture may be regarded as field
operators. In this approach the transition amplitudes for the particle are
constructed in terms of two-component functions in the unitary representations
of the Lorentz group.",0203034v1
2007-01-05,Restoration of Lorentz Invariance of 't Hooft-Polyakov Monopole Field,"Lorentz invariance is broken for the non-Abelian monopoles. Here we will
consider the case of 't Hooft-Polyakov monopole and show that the Lorentz
invariance of its field will be restored using Dirac quantization.",0701045v1
2000-09-07,New Lorentz spaces for the restricted weak-type Hardy's inequalities,"Associated to the class of restricted-weak type weights for the Hardy
operator, we find a new class of Lorentz spaces for which the normability
property holds. This result is analogous to the characterization given by
Sawyer for the classical Lorentz spaces. We also show that these new spaces are
very natural to study the existence of equivalent norms described in terms of
the maximal function",0009072v1
2004-12-09,On Lorentz dynamics : From group actions to warped products via homogeneous spaces,"We show a geometric rigidity of isometric actions of non compact (semisimple)
Lie groups on Lorentz manifolds. Namely, we show that the manifold has a warped
product structure of a Lorentz manifold with constant curvature by a Riemannian
manifold.",0412195v1
2005-06-20,A nested embedding theorem for Hardy-Lorentz spaces with applications to coefficient multiplier problems,"We prove a nested embedding theorem for Hardy-Lorentz spaces and use it to
find coefficient multiplier spaces of certain non-locally convex Hardy-Lorentz
spaces into various target spaces such as Lebesgue sequence spaces, other Hardy
spaces, and analytic mixed norm spaces.",0506406v1
2007-03-27,On the Periodic Lorentz Gas and the Lorentz Kinetic Equation,"We prove that the Boltzmann-Grad limit of the Lorentz gas with periodic
distribution of scatterers cannot be described with a linear Boltzmann
equation. This is at variance with the case of a Poisson distribution of
scatterers, for which the convergence to the linear Boltzmann equation has been
proved by Gallavotti [Phys. Rev. (2) 185 (1969), p. 308].",0703812v1
1999-05-19,Electromagnetic Field Tensor and Lorentz Force as Consequence of the Geometry of Minkowskian Spacetime,"We show that the electromagnetic field tensor and the Lorentz Force are both
a natural consequence of the geometric structure of Minkowskian space, being
related to infinitesimal boosts and rotations in spacetime. The longstanding
issue about the apparent empirical origin of the Lorentz Force is clarified.",9905013v2
2002-12-12,Lorentz Transformations from Reflections:Some Applications,"We point out, by exhibiting two examples and mentioning a third one, that it
is sometimes useful to consider Lorentz transformations as generated from
hyperplane or line reflections. One example concerns the construction of boosts
linking two given 4-vectors, the other one concerns the Minkowski geometric
understanding of V. Moretti's polar decomposition of orthochronous Lorentz
matrices.",0212038v1
2006-12-06,Isomorphism between Galilean and Lorentz Transformations and Special Relativity in Galilean Algebra,"We have shown that Lorentz transformation is not necessary to present
relativistic relative velocity. A modified definition of velocity together with
Galilean transformation is equivalent to relativistic relative velocity. On the
other hand, Galilean relative velocity can be presented as a Lorentz
transformation. Again the definition of velocity requires a modification.",0612019v1
2006-12-18,Reciprocity Independent Lorentz Transformation,"We have defined slowness (or reciprocal velocity, corresponding to velocity
v) as cc/v, where c is the speed of light. It is observed that the relative
velocity remains invariant if the velocities are replaced by corresponding
slownesses i.e. relative motion in one dimension is reciprocal symmetric.
Reciprocity operation, which converts a velocity to the corresponding slowness,
is found. Lorentz transformation is generalized so that Lorentz invariance is
maintained if velocities are replaced by corresponding slownesses.",0612057v1
2006-09-29,The Lorentz - invariant deformation of the Whitham system for the non-linear Klein-Gordon equation,"We consider the deformation of the Whitham system for the non-linear
Klein-Gordon equation having the Lorentz-invariant form. Using the Lagrangian
formalism of the initial system we obtain the first non-trivial correction to
the Whitham system in the Lorentz-invariant approach.",0609071v1
2005-03-27,Brownstein's Whole-Partial Derivatives: The Case of the Lorentz Gauge,"In this brief note we show that the usual Lorentz gauge is not satisfied by
the Lienard-Wiechert potentials, then, using Brownstein's concept of
""whole-partial"" derivatives we introduce the generalized expression for the
Lorentz gauge showing that it is satisfied by the LW-potentials.",0503207v1
2005-08-10,Symmetry breaking from Lorentz transformation,"Symmetry breaking is discussed in this paper which comes from the Lorentz
transformation of special relativity and changes our view that two relatively
moving bodies always have the relative speed equal in magnitude and opposite in
direction. An appeal was made for the test of Lorentz transformation in a
multimedia environment which has the fundamental significance that it may
reveal the origin of symmetry breaking in many physical phenomena.",0508061v1
2005-09-14,Multipole Radiation in Lorentz Gauge,"The multipole expansion for electromagnetic radiation, valid for all
wave-lengths and all distances from bounded sources, is presented in Lorentz
gauge, rather than the usual Coulomb gauge. This gauge is likely to be
preferred in applications where one wishes to maintain manifest Lorentz
invariance. The presentation also serves as a useful exercise in the use of
vector spherical harmonics.",0509122v2
2006-05-24,Lorentz Transformation from Symmetry of Reference Principle,"The Lorentz Transformation is traditionally derived requiring the Principle
of Relativity and light-speed universality. While the latter can be relaxed,
the Principle of Relativity is seen as core to the transformation. The present
letter relaxes both statements to the weaker, Symmetry of Reference Principle.
Thus the resulting Lorentz transformation and its consequences (time
dilatation, length contraction) are, in turn, effects of how we manage space
and time.",0605212v1
1997-07-17,Lorentz-Invariant Hamiltonian and Riemann Hypothesis,"We have given some arguments that a two-dimensional Lorentz-invariant
Hamiltonian may be relevant to the Riemann hypothesis concerning zero points of
the Riemann zeta function. Some eigenfunction of the Hamiltonian corresponding
to infinite-dimensional representation of the Lorentz group have many
interesting properties. Especially, a relationship exists between the zero zeta
function condition and the absence of trivial representations in the wave
function.",9707036v1
2003-10-21,Special relativity and reduced spin density matrices,"We derive the general formula for Lorentz-transformed spin density matrix. It
is shown that an appropriate Lorentz transformation can prduce totally
unpolarized state out of pure one. Further properties, as depurification by an
arbitrary Lorentz boost and its relation to the localization properties are
also discussed.",0310132v1
2007-04-15,Non-Associativity of Lorentz Transformation and Associative Reflection Symmetric Transformation,"Each of the two moving observers observes the relative velocity of the other.
The two velocities should be equal and opposite. We have shown that this
relativistic requirement is not fulfilled by Lorentz transformation. We have
also shown that the reason is that Lorentz transformation is not associative.
Reciprocal symmetric transformation is associative and fulfills relativistic
requirements.",0704.1894v1
2008-03-14,Lorentz Violation and Torsion,"In this proceedings, similarities between the structure of theories with
Lorentz violation and theories with constant torsion in flat spacetime are
exploited to place bounds on torsion components. An example is given showing
the analysis leading to bounds on the axial-vector and mixed-symmetry
components of torsion, based on a dual-maser experiment.",0803.2228v1
2008-12-30,An alternative to relativistic transformation of special relativity based on the first principles,"A new relativistic transformation in the velocity space (here named the
differential Lorentz transformation) is formulated solely from the principle of
relativity and the invariance of the speed of light. The differential Lorentz
transformation is via transforming physical quantities, instead of space-time
coordinates, to make laws of nature form-invariant. The differential Lorentz
transformation may provide a way to resolve the incompatibility of the theory
of special relativity and the quantum theory.",0812.5029v1
2010-04-20,Typical recurrence for the ehrenfest wind-tree model,"We show that the typical wind-tree model, in the sense of Baire, is recurrent
and has a dense set of periodic orbits. The recurrence result also holds for
the Lorentz gas : the typical Lorentz gas, in the sense of Baire, is recurrent.
These Lorentz gases need not be of finite horizon!",1004.3455v1
2010-07-28,Lorentz-invariant Bohmian description of inelastic scattering in QFT,"The Lorentz-invariant S-matrix elements in interacting quantum field theory
(QFT) are used to represent the QFT state by a Lorentz-invariant many-time wave
function. Such a wave function can be used to describe inelastic scattering
processes (involving particle creation and destruction) by Bohmian particle
trajectories satisfying relativistic-covariant equations of motion.",1007.4946v1
2010-07-31,A New Lorentz-Violating Model of Neutrino Oscillations,"A new model for neutrino oscillations is introduced, in which mass-like
behavior is seen at high energies, but various behavior can be predicted at low
energies. The model employs no neutrino masses, but instead relies on the
Lorentz-violating parameters a and c. Oscillations into antineutrinos and
sterile neutrinos are also considered.",1008.0105v1
2010-08-02,Lorentz and CPT violation in neutrino oscillations,"Neutrino oscillations in the presence of Lorentz violation can present novel
observable signals in both long- and short-baseline experiments. In this talk
we describe the theory and its different regimes depending on properties of the
experiments. CPT violation, its systematic search and possible connections to
latest results are also presented.",1008.0411v1
2010-08-09,Lorentz violation in the linearized gravity,"We study some consequences of the introduction of a Lorentz-violating
modification term in the linearized gravity, which leads to modified dispersion
relations for gravitational waves in the vacuum. We also discuss possible
mechanisms for the induction of such a term in the Lagrangian.",1008.1497v1
2010-08-10,"Spontaneous Lorentz Violation, Nambu-Goldstone Modes, and Massive Modes","In any theory with spontaneous symmetry breaking, it is important to account
for the massless Nambu-Goldstone and massive Higgs modes. In this short review,
the fate of these modes is examined for the case of a bumblebee model, in which
Lorentz symmetry is spontaneously broken.",1008.1805v1
2010-08-17,Higher-order Lorentz violations in electrodynamics,"The Standard-Model Extension (SME) provides a theoretical framework for tests
of Lorentz invariance. To date, most studies have focused on the minimal SME,
which restricts attention to operators of renormalizable dimension. Here, we
review recent studies involving the nonrenormalizable photon sector of the SME.",1008.2925v1
2010-10-21,Topics in Lorentz and CPT violation,"This talk given at the CPT'10 meeting provides a brief introduction to
Lorentz and CPT violation and outlines a few recent developments in the
subject.",1010.4559v1
2011-01-23,Lorentz-invariant membranes and finite matrix approximations,"The question of Lorentz invariance for finite N approximations of
relativistic membranes is addressed. We find that one of the classical
manifestations of Lorentz-invariance is not possible for NxN matrices (at least
when N=2 or 3). How the symmetry is restored in the large N limit is studied
numerically.",1101.4403v1
2011-05-04,Remarks on a challenge to the relation between $CPT$ and Lorentz violation,"The objection [arXiv:1103.0168] to my theorem [arXiv:hep-ph/0201258] that
violation of $CPT$ symmetry implies violation of Lorentz covariance is based on
a nonlocal model in which time-ordered products are not well defined. I used
covariance of time-ordered products as the condition for Lorentz covariance;
therefore the proposed objection is not relevant to my result.",1105.0927v1
2011-06-12,Relativistic Landau-Aharonov-Casher quantization based on the Lorentz symmetry violation background,"Based on the discussions about the Aharonov-Casher effect in the Lorentz
symmetry violation background, we show that the analogue of the relativistic
Landau quantization in the Aharonov-Casher setup can be achieved in the
Lorentz-symmetry violation background.",1106.2324v1
2011-09-04,Testing Lorentz symmetry with atoms and Light,"This article reports on the Fifth Meeting on CPT and Lorentz Symmetry,
CPT'10, held at the end of June 2010 in Bloomington, Indiana, USA. The focus is
on recent tests of Lorentz symmetry using atomic and optical physics.",1109.0768v1
2012-03-03,Three Dimensional Lorentz homogeneous spaces and the Petrov classification,"In this note, we verify the classification of local geometries given by A.Z.
Petrov. First, we determine criteria for identifying a given 3D Lorentz
homogeneous space in Petrov's classification. Then, we identify all
inequivalent 1D subalgebras of all real 4D Lie algebras and determine which of
these give rise to a homogeneous space admitting an invariant Lorentz metric.",1203.0625v1
2012-11-14,"Real Interpolation method, Lorentz spaces and refined Sobolev inequalities","In this article we give a straightforward proof of refined inequalities
between Lorentz spaces and Besov spaces and we generalize previous results of
H. Bahouri and A. Cohen. Our approach is based in the characterization of
Lorentz spaces as real interpolation spaces. We will also study the sharpness
and optimality of these inequalities.",1211.3320v1
2012-12-20,On some discrete subgroups of the Lorentz group,"Some discrete subgroups of the Lorentz group are found using Fedorov's
parametrization by means of complex vector-parameter. It is shown that the
discrete subgroup of the Lorentz group, which have not fixed points, are
contained in boosts along a spatial direction for time-like and space-like
vectors and are discrete subgroups of the group SO(1,1), whereas discrete
subgroups of isotropic vector are subgroups of SO(1,1)\times E(1,1).",1301.1636v1
2013-01-24,Width of photon decay in magnetic field: elementary semiclassical derivation and sensitivity to Lorentz violation,"We present an elementary derivation of the width of photon decay in a weak
magnetic field using the semiclassical method of worldline instantons. The
calculation is generalized to a model of quantum electrodynamics with broken
Lorentz symmetry. Implications for the search of deviations from Lorentz
invariance in the cosmic ray experiments are discussed.",1301.5707v1
2013-01-29,Convex valuations invariant under the Lorentz group,"We give an explicit classification of translation-invariant,
Lorentz-invariant continuous valuations on convex sets. We also classify the
Lorentz-invariant even generalized valuations.",1301.6866v2
2013-03-21,On the Origin of the Lorentz Transformation,"The Lorentz Transformation, which is considered as constitutive for the
Special Relativity Theory, was invented by Voigt in 1887, adopted by Lorentz in
1904, and baptized by Poincar\'e in 1906. Einstein probably picked it up from
Voigt directly.",1303.5309v2
2013-04-08,Four-dimensional aether-like Lorentz-breaking QED revisited and problem of ambiguities,"In this paper, we consider the perturbative generation of the CPT-even
aether-like Lorentz-breaking term in the extended Lorentz-breaking QED within
different approaches and discuss its ambiguities.",1304.2256v2
2013-05-22,Generalized Lorentz Transformations,"Generalized Lorentz transformations with modified velocity parameter are
considered. Lorentz transformations depending on the mass of the observer are
suggested.The modified formula for the addition of velocities remarkably
preserves the constancy of the velocity of light for all observers. The Doppler
red shift is affected and can provide a test of such generalisations.",1305.5224v3
2013-07-25,Lorentz and CPT violation in the Neutrino Sector,"Searches for Lorentz and CPT violation using neutrino oscillations and the
prospects for future tests using neutrino time-of-flight measurements and
beta-decay experiments are presented.",1307.6845v1
2013-10-28,Using Binary Pulsars to Test Lorentz Symmetry in the Gravitational Sector,"I review some of the major developments in the theoretical background and
experimental uses of binary pulsars to explore local Lorentz invariance in the
gravitational sector and its possible violation.",1310.7309v1
2014-10-06,Renormalization and asymptotic states in Lorentz-violating QFT,"Radiative corrections in quantum field theories with small departures from
Lorentz symmetry alter structural aspects of the theory, in particular the
definition of asymptotic single-particle states. Specifically, the mass-shell
condition, the standard renormalization procedure as well as the
Lehmann-Symanzik-Zimmermann reduction formalism are affected.",1410.1345v1
2014-10-21,Comments on initial conditions for the Abraham-Lorentz(-Dirac) equation,"An accelerating electric charge coupled to its own electromagnetic (EM) field
both emits radiation and experiences the radiation's reaction as a
(self-)force. Considering the system from an Effective Field Theory
perspective, and using the physical initial conditions of no incoming radiation
can help resolve many of the problems associated with the often considered
""notorious"" Abraham-Lorentz / Abraham-Lorentz-Dirac equations.",1410.5871v1
2015-05-13,Lorentz violation correction to the Aharonov-Bohm scattering,"In this paper, using a (2+1)-dimensional field theory approach, we study the
Aharonov-Bohm (AB) scattering with Lorentz symmetry breaking. We obtain the
modified scattering amplitude to the AB effect due to the small Lorentz
violation correction in the breaking parameter and prove that up to one loop
the model is free from ultraviolet divergences.",1505.03238v2
2015-11-18,Quasi-minimal Lorentz Surfaces with Pointwise 1-type Gauss Map in Pseudo-Euclidean 4-Space,"A Lorentz surface in the four-dimensional pseudo-Euclidean space with neutral
metric is called quasi-minimal if its mean curvature vector is lightlike at
each point. In the present paper we obtain the complete classification of
quasi-minimal Lorentz surfaces with pointwise 1-type Gauss map.",1511.05684v1
2015-11-17,Lorentz-violating quantum electrodynamics in two-dimensional aether-superspace,"The two-dimensional aether-superspace is constructed and the superfield
techniques are applied to the study of dynamical generation of mass in the
Lorentz-violating supersymmetric quantum electrodynamics in two dimensions of
spacetime. It is shown that such model presents a dynamical generation of mass
to the gauge aether-superfield and its dispersion relation has the structure
similar of the CPT-even Lorentz-breaking models.",1511.05918v1
2016-01-18,Anisotropic Hardy-Lorentz spaces with variable exponents,"In this paper we introduce Hardy-Lorentz spaces with variable exponents
associated to dilation in ${\Bbb R}^n$. We establish maximal characterizations
and atomic decompositions for our variable exponent anisotropic Hardy-Lorentz
spaces.",1601.04487v3
2016-06-02,On orders of approximation functions of generalized smoothness in Lorentz spaces,"This paper considers the Lorentz space with mixed norm of periodic functions
of many variables and of the generalized Nikol'skii -- Besov classes. Estimates
for the order of approximation of the generalized Nikol'skii -- Besov classes
by partial sums of Fourier's series for multiple trigonometric system in
Lorentz spaces with mixed norm are obtained.",1606.00700v2
2016-07-15,Extra dimensions and violations of Lorentz symmetry,"We use experimental limits on Lorentz violation to obtain new constraints on
Kaluza-Klein-type theories in which the extra dimensions may be large but do
not necessarily have units of length. The associated variation in fundamental
quantities such as rest mass must occur slowly, on cosmological scales.",1607.04580v1
2016-07-18,Spacetime Variation of Lorentz-Violation Coefficients at Nonrelativistic Scale,"When the Standard-Model Extension (SME) is applied in curved spacetime, the
Lorentz-violation coefficients must depend on spacetime position. This work
describes some of the consequences of this spacetime variation. We focus on
effects that appear at a nonrelativistic scale and extract sensitivity of
completed experiments to derivatives of SME coefficient fields.",1607.05211v1
2016-07-28,Preliminary Design of a Pendulum Experiment for Searching for a Lorentz-Violation Signal,"This work mainly presents a preliminary design for a pendulum experiment with
both the source mass and the test mass in a striped pattern to amplify the
Lorentz-violation signal, since the signal is sensitive to edge effects.",1607.08301v1
2016-10-28,Recent Progress in Lorentz and CPT Violation,"This contribution to the CPT'16 meeting briefly highlights some of the recent
progress in the phenomenology of Lorentz and CPT violation, with emphasis on
research performed at the Indiana University Center for Spacetime Symmetries.",1610.09284v1
2016-10-28,Testing Lorentz and CPT Symmetries in Penning Traps,"A modified Dirac equation with general Lorentz- and CPT-violating operators
in the electromagnetic field is studied. Constraints on and possible
sensitivities to Lorentz-violating coefficients in the nonminimal sector up to
mass-dimension six can be obtained by analyzing Penning-trap results involving
anomaly frequencies.",1610.09357v1
2018-02-14,Spacetime orientation and the meaning of Lorentz invariance in general relativity,"The parity violation at the level of weak interactions and other similar
discrete symmetries breaking show that the invariance of laws under the full
group of Lorentz transformations can not be taken granted. We examine the
principle of Lorentz invariance under the general theory of relativity, and
demonstrate the importance of a concept of the spacetime orientation as part of
the causal structure of spacetime.",1802.05290v1
2019-05-01,Signals for Lorentz violation in gravitational waves,"Lorentz violations in gravitational waves are investigated. Plane-wave
solutions for arbitrary gauge-invariant violations in linearized gravity are
constructed. Signatures of Lorentz violation include dispersion, birefringence,
and anisotropies. Modifications to waves from coalescing compact binaries and
to strain signals in gravitational-wave detectors are derived.",1905.00409v1
2013-08-09,Sensitivity of atmospheric neutrinos in Super-Kamiokande to Lorentz violation,"This talk, given at CPT'13, showed Super-Kamiokande atmospheric-neutrino
Monte Carlo sensitivity to Lorentz-violation effects using the perturbative
model derived from the Standard-Model Extension.",1308.2210v1
2014-06-11,Ambiguities of the CPT-even aether-like Lorentz-breaking term at the finite temperature,"In this paper, we consider the finite temperature behaviour of the CPT-even
aether-like Lorentz-breaking term in the extended Lorentz-breaking QED and
demonstrate that its ambiguities whose presence has been shown earlier in the
zero temperature case stay also at the finite temperature.",1406.2873v1
2016-05-24,A local characterization for constant curvature metrics in 2-dimensional Lorentz manifolds,"In this paper we define Fermi-type coordinates in a 2-dimensional Lorentz
manifold, and use this coordinate system to provide a local characterization of
constant Gaussian curvature metrics for such manifolds, following a classical
result from Riemann. We then exhibit particular isometric immersions of such
metrics in the pseudo-Riemannian ambients L^3 (i.e., usual Lorentz-Minkowski
space) and R^3_2 (i.e., R^3 endowed with an index 2 flat metric).",1605.07573v1
2016-08-26,Positive operators of Extended Lorentz cones,"In this paper necessary conditions and sufficient conditions are given for a
linear operator to be a positive operators of an Extended Lorentz cone.
Similarities and differences with the positive operators of Lorentz cones are
investigated.",1608.07455v2
2016-12-09,Orlicz--Lorentz centroid bodies,"We extend the definition of the centroid body operator to an Orlicz--Lorentz
centroid body operator on the star bodies in $\mathbb R^n$, and establish the
sharp affine isoperimetric inequality that bounds (from below) the volume of
the Orlicz--Lorentz centroid body of any convex body containing the origin in
its interior by the volume of this convex body.",1612.03215v2
2017-07-29,Radiation Reaction in a Lorentz-Violating Electrodynamics,"We study radiation reaction in a Lorentz violating electrodynamics [1]. We
explore the possible modification whatsoever present in the radiation reaction
force experienced by an accelerating charge in the modified Maxwell theory.
However it turns out that radiation reaction receives no change due to Lorentz
violation whereas electromagnetic mass manifests anisotropy.",1707.09522v1
2019-06-05,Nonminimal Lorentz Violation in Linearized Gravity,"This contribution to the CPT'19 meeting provides a brief overview of recent
theoretical studies of nonminimal Lorentz violation in linearized gravity.
Signatures in gravitational waves from coalescing compact binaries are
discussed.",1906.02267v1
2019-06-11,Comparative Penning-Trap Tests of Lorentz and CPT Symmetry,"The theoretical and experimental prospects for Lorentz- and CPT-violating
quantum electrodynamics in Penning traps are reviewed in this work. With the
recent reported results for the measurements of magnetic moments for both
protons and antiprotons, improvements with factors of up to 3000 for the
constraints of various coefficients for Lorentz and CPT violation are obtained.",1906.04364v1
2019-09-22,The boundedness of the Hilbert transformation from one rearrangement invariant Banach space into another and applications,"In this paper, we study the boundedness of the Hilbert transformation in
Lorentz function spaces, thereby complementing classical results of Boyd. We
also characterize the optimal range of a triangular truncation operator in
Schatten-Lorentz ideals. These results further entail sharp commutator
estimates and applications to operator Lipschitz functions in Schatten-Lorentz
ideals.",1909.10897v1
2019-10-03,Extrapolation in Weighted Classical and Grand Lorentz Spaces. Application to the Boundedness of Integral operators,"We establish weighted extrapolation theorems in classical and grand Lorentz
spaces. As a consequence we have the weighted boundedness of operators of
Harmonic Analysis in grand Lorentz spaces. We treat both cases: diagonal and
off-diagonal ones.",1910.01362v1
2017-09-07,Invicem Lorentz Oscillator Model (ILOM),"We present detailed theoretical model of electron motion inside of an atom or
molecule when subjected to electro-magnetic wave. This theoretical model, that
we called Invicem Lorentz Oscillator Model (ILOM), contains Lorentz Oscillator
Model (LOM) as a simplified approximation. The ILOM demonstrates artificial
nature of the separation of descriptions of electromagnetic wave propagation in
media into Linear and Nonlinear Optics.",1709.02466v1
2017-11-30,Vacuum Cherenkov radiation for Lorentz-violating fermions,"The current paper summarizes the content of a talk given on vacuum Cherenkov
radiation emitted by Lorentz-violating fermions that are described in the
context of the Standard-Model Extension. The decay rate will be obtained for
various sets of controlling coefficients that will subsequently be constrained
using cosmic-ray data.",1711.11167v1
2019-02-12,Lorentz-invariant second-order tensors and an irreducible set of matrices,"We prove that, up to multiplication by a scalar, the Minkowski metric tensor
is the only second-order tensor that is Lorentz-invariant. To prove this, we
show that a specific set of three $4\times 4$ matrices, made of two rotation
matrices plus a Lorentz boost, is irreducible.",1902.09300v1
2020-06-16,Modified Excluded Volume Hadron Resonance Gas Model with Lorentz Contraction,"In this work we discuss a modified version of Excluded Volume Hadron
Resonance Gas model and also study the effect of Lorentz contraction of the
excluded volume on scaled pressure and susceptibilities of conserved charges.
We find that the Lorentz contraction, coupled with the variety of excluded
volume parameters reproduce the lattice QCD data quite satisfactorily.",2006.08985v2
2020-09-03,Nonminimal Lorentz-Violating Extensions of Gauge Field Theories,"A general method is presented to build all gauge-invariant terms in gauge
field theories, including quantum electrodynamics and quantum chromodynamics.
It is applied to two experiments, light-by-light scattering and deep inelastic
scattering, to extract first bounds on certain nonminimal coefficients for
Lorentz violation.",2009.01767v1
2021-09-07,Lorentz violation in the matter-gravity sector,"We construct the general Lorentz-violating effective field theory in curved
spacetime and the corresponding nonrelativistic Hamiltonian in the Earth's
gravitational field. Applying this general framework to three types of
experiments, free-dropping, interferometer, and bound-state experiments, we
extract first constraints on certain new coefficients in the matter-gravity
sector.",2109.03258v1
2023-01-17,"Lorentz Violation, CPT violation, and Spectroscopy Experiments","This presentation discusses some of the signals for Lorentz violation
potentially observable in atomic spectroscopy and clock-comparison experiments.
The emphasis of the discussion is on how the angular-momentum quantum numbers
of the states involved in the transition determine the properties of the
possible sidereal variation of the transition frequency.",2301.06833v1
2023-01-30,Factorization of the Lorentz transformations,"The article shows how the factorization of an arbitrary Lorentz
transformation is performed. That is, representation of an arbitrary Lorentz
transformation as a sequence of spatial rotation and boost or boost and spatial
rotation. Relations are obtained that determine the required boosts and turns.",2302.02791v1
2023-03-01,Real Interpolation for mixed Lorentz spaces and Minkowski's inequality,"We prove embeddings and identities for real interpolation spaces between
mixed Lorentz spaces. This partly relies on Minkowski's (reverse) integral
inequality in Lorentz spaces $L^{p,r}(X)$ under optimal assumptions on the
exponents $(p,r)\in (0,\infty)\times (0,\infty]$.",2303.00607v2
2024-01-03,Anisotropic Ginzburg-Landau model for superconductivity with five-dimensional operators,"This paper presents the effects of non-minimal Lorentz-violation operators in
superconductivity. By constructing a Lorentz-Violating Ginzburg-Landau theory
of superconductivity with a five-dimensional operator, we discuss the influence
of higher dimensional Lorentz-Violating operators in the London's depth
penetration, in the coherence length and critical magnetic field.",2401.01778v1
1998-05-07,Discovery of z=0.0912 and z=0.2212 Damped Lyman-alpha Absorption Line Systems Toward the Quasar OI 363: Limits on the Nature of Damped Lyman-alpha Galaxies,"The discovery of a z_abs = 0.0912 damped Lyman-alpha absorption-line system
in the HST-FOS ultraviolet spectrum of the quasar OI 363 (0738+313) is
reported. This is the lowest redshift quasar damped Lyman-alpha system known.
Its neutral hydrogen column density is N(HI) = 1.5(+/- 0.2) E21 atoms/cm^2,
which easily exceeds the classical criterion for damped Lyman-alpha of N(HI)
greater than or equal to 2E20 atoms/cm^2. Remarkably, a z_abs = 0.2212 damped
system with N(HI) = 7.9(+/- 1.4) E20 atoms/cm^2 has also been discovered in the
same spectrum.
  In the past, the standard paradigm for damped Lyman-alpha systems has been
that they arise in galactic or protogalactic HI disks with low impact
parameters in luminous galaxies. However, WIYN imaging of the OI 363 field
shows that none of the galaxies visible in the vicinity of the quasar is a
luminous gas-rich spiral with low impact parameter, either at z = 0.0912 or z =
0.2212. Thus, these damped systems are among the clearest examples yet of cases
that are inconsistent with the standard damped Lyman-alpha - HI-disk paradigm.",9805093v1
2008-01-24,Attenuation of small-amplitude oscillations in a prominence-corona model with a transverse magnetic field,"Small-amplitude prominence oscillations are usually damped after a few
periods. We study the attenuation of non-adiabatic magnetoacoustic waves in a
slab prominence embedded in the coronal medium. We assume an equilibrium
configuration with a transverse magnetic field to the slab axis and investigate
wave damping by thermal conduction and radiative losses. The differential MHD
equations that govern linear slow and fast modes are numerically solved to
obtain the complex oscillatory frequency and the corresponding eigenfunctions.
We find that coronal thermal conduction and radiative losses from the
prominence plasma reveal as the most relevant damping mechanisms. Both
mechanisms govern together the attenuation of hybrid modes, whereas prominence
radiation is responsible for the damping of internal modes and coronal
conduction essentially dominates the attenuation of external modes. In
addition, the energy transfer between the prominence and the corona caused by
thermal conduction has a noticeable effect on the wave stability, radiative
losses from the prominence plasma being of paramount importance for the thermal
stability of fast modes. We conclude that slow modes are efficiently damped,
with damping times compatible with observations. On the contrary, fast modes
are less attenuated by non-adiabatic effects and their damping times are
several orders of magnitude larger than those observed. The presence of the
corona causes a decrease of the damping times with respect to those of an
isolated prominence slab, but its effect is still insufficient to obtain
damping times of the order of the period in the case of fast modes.",0801.3744v2
2010-04-26,Selective spatial damping of propagating kink waves due to resonant absorption,"There is observational evidence of propagating kink waves driven by
photospheric motions. These disturbances, interpreted as kink
magnetohydrodynamic (MHD) waves are attenuated as they propagate upwards in the
solar corona. In this paper we show that resonant absorption provides a simple
explanation to the spatial damping of these waves. Kink MHD waves are studied
using a cylindrical model of solar magnetic flux tubes which includes a
non-uniform layer at the tube boundary. Assuming that the frequency is real and
the longitudinal wavenumber complex, the damping length and damping per
wavelength produced by resonant absorption are analytically calculated. The
damping length of propagating kink waves due resonant absorption is a
monotonically decreasing function of frequency. For kink waves with low
frequencies the damping length is exactly inversely proportional to frequency
and we denote this as the TGV relation. When moving to high frequencies the TGV
relation continues to be an exceptionally good approximation of the actual
dependency of the damping length on frequency. This dependency means that
resonant absorption is selective as it favours low frequency waves and can
efficiently remove high frequency waves from a broad band spectrum of kink
waves. It is selective as the damping length is inversely proportional to
frequency so that the damping becomes more severe with increasing frequency.
This means that radial inhomogeneity can cause solar waveguides to be a natural
low-pass filter for broadband disturbances. Hence kink wave trains travelling
along, e.g., coronal loops, will have a greater proportion of the high
frequency components dissipated lower down in the atmosphere. This could have
important consequences with respect to the spatial distribution of wave heating
in the solar atmosphere.",1004.4468v1
2011-04-10,Spatial Damping of Propagating Kink Waves Due to Resonant Absorption: Effect of Background Flow,"Observations show the ubiquitous presence of propagating magnetohydrodynamic
(MHD) kink waves in the solar atmosphere. Waves and flows are often observed
simultaneously. Due to plasma inhomogeneity in the perpendicular direction to
the magnetic field, kink waves are spatially damped by resonant absorption. The
presence of flow may affect the wave spatial damping. Here, we investigate the
effect of longitudinal background flow on the propagation and spatial damping
of resonant kink waves in transversely nonuniform magnetic flux tubes. We
combine approximate analytical theory with numerical investigation. The
analytical theory uses the thin tube (TT) and thin boundary (TB) approximations
to obtain expressions for the wavelength and the damping length. Numerically,
we verify the previously obtained analytical expressions by means of the full
solution of the resistive MHD eigenvalue problem beyond the TT and TB
approximations. We find that the backward and forward propagating waves have
different wavelengths and are damped on length scales that are inversely
proportional to the frequency as in the static case. However, the factor of
proportionality depends on the characteristics of the flow, so that the damping
length differs from its static analogue. For slow, sub-Alfvenic flows the
backward propagating wave gets damped on a shorter length scale than in the
absence of flow, while for the forward propagating wave the damping length is
longer. The different properties of the waves depending on their direction of
propagation with respect to the background flow may be detected by the
observations and may be relevant for seismological applications.",1104.1791v1
2013-02-08,On the Damping-Induced Self-Recovery Phenomenon in Mechanical Systems with Several Unactuated Cyclic Variables,"The damping-induced self-recovery phenomenon refers to the fundamental
property of underactuated mechanical systems: if an unactuated cyclic variable
is under a viscous damping-like force and the system starts from rest, then the
cyclic variable will always move back to its initial condition as the actuated
variables come to stop. The regular momentum conservation phenomenon can be
viewed as the limit of the damping-induced self-recovery phenomenon in the
sense that the self-recovery phenomenon disappears as the damping goes to zero.
This paper generalizes the past result on damping-induced self-recovery for the
case of a single unactuated cyclic variable to the case of multiple unactuated
cyclic variables. We characterize a class of external forces that induce new
conserved quantities, which we call the damping-induced momenta. The
damping-induced momenta yield first-order asymptotically stable dynamics for
the unactuated cyclic variables under some conditions, thereby inducing the
self-recovery phenomenon. It is also shown that the viscous damping-like forces
impose bounds on the range of trajectories of the unactuated cyclic variables.
Two examples are presented to demonstrate the analytical discoveries: the
planar pendulum with gimbal actuators and the three-link planar manipulator on
a horizontal plane.",1302.2109v1
2016-07-06,Damping of Alfven waves by Turbulence and its Consequences: from Cosmic-Rays Streaming to Launching Winds,"This paper considers turbulent damping of Alfven waves in magnetized plasmas.
We identify two cases of damping, one related to damping of cosmic rays
streaming instability, the other related to damping of Alfven waves emitted by
a macroscopic wave source, e.g. stellar atmosphere. The physical difference
between the two cases is that in the former case the generated waves are
emitted in respect to the local direction of magnetic field, in the latter in
respect to the mean field. The scaling of damping is different in the two
cases. We the regimes of turbulence ranging from subAlfvenic to superAlfvenic
we obtain analytical expressions for the damping rates and define the ranges of
applicability of these expressions. Describing the damping of the streaming
instability, we find that for subAlfvenic turbulence the range of cosmic ray
energies influenced by weak turbulence is unproportionally large compared to
the range of scales that the weak turbulence is present. On the contrary, the
range of cosmic ray energies affected by strong Alfvenic turbulence is rather
limited. A number of astrophysical applications of the process ranging from
launching of stellar and galactic winds to propagation of cosmic rays in
galaxies and clusters of galaxies is considered. In particular, we discuss how
to reconcile the process of turbulent damping with the observed isotropy of the
Milky Way cosmic rays.",1607.02042v1
2018-01-18,Quantum Landau damping in dipolar Bose-Einstein condensates,"We consider Landau damping of elementary excitations in Bose-Einstein
condensates (BECs) with dipolar interactions. We discuss quantum and
quasi-classical regimes of Landau damping. We use a generalized wave-kinetic
description of BECs which, apart from the long range dipolar interactions, also
takes into account the quantum fluctuations and the finite energy corrections
to short-range interactions. Such a description is therefore more general than
the usual mean field approximation. The present wave-kinetic approach is well
suited for the study of kinetic effects in BECs, such as those associated with
Landau damping, atom trapping and turbulent diffusion. The inclusion of quantum
fluctuations and energy corrections change the dispersion relation and the
damping rates, leading to possible experimental signatures of these effects.
  Quantum Landau damping is described with generality, and particular examples
of dipole condensates in two and three dimensions are studied. The occurrence
of roton-maxon configurations, and their relevance to Landau damping is also
considered in detail, as well as the changes introduced by the three different
processes, associated with dipolar interactions, quantum fluctuations and
finite energy range collisions. The present approach is mainly based on a
linear perturbative procedure, but the nonlinear regime of Landau damping,
which includes atom trapping and atom diffusion, is also briefly discussed.",1801.06256v1
2019-02-26,Enhanced Gilbert Damping in Re doped FeCo Films: A Combined Experimental and Theoretical Study,"The effects of rhenium doping in the range 0 to 10 atomic percent on the
static and dynamic magnetic properties of Fe65Co35 thin films have been studied
experimentally as well as with first principles electronic structure
calculations focusing on the change of the saturation magnetization and the
Gilbert damping parameter. Both experimental and theoretical results show that
the saturation magnetization decreases with increasing Re doping level, while
at the same time Gilbert damping parameter increases. The experimental low
temperature saturation magnetic induction exhibits a 29 percent decrease, from
2.31 T to 1.64 T, in the investigated doping concentration range, which is more
than predicted by the theoretical calculations. The room temperature value of
the damping parameter obtained from ferromagnetic resonance measurements,
correcting for extrinsic contributions to the damping, is for the undoped
sample 0.0027, which is close to the theoretically calculated Gilbert damping
parameter. With 10 atomic percent Re doping, the damping parameter increases to
0.0090, which is in good agreement with the theoretical value of 0.0073. The
increase in damping parameter with Re doping is explained by the increase in
density of states at Fermi level, mostly contributed by the spin-up channel of
Re. Moreover, both experimental and theoretical values for the damping
parameter are observed to be weakly decreasing with decreasing temperature.",1902.09896v1
2020-05-31,Optimal decay rates of the compressible Euler equations with time-dependent damping in $\mathbb R^n$: (I) under-damping case,"This paper is concerned with the multi-dimensional compressible Euler
equations with time-dependent damping of the form
$-\frac{\mu}{(1+t)^\lambda}\rho\boldsymbol u$ in $\mathbb R^n$, where $n\ge2$,
$\mu>0$, and $\lambda\in[0,1)$. When $\lambda>0$ is bigger, the damping effect
time-asymptotically gets weaker, which is called under-damping. We show the
optimal decay estimates of the solutions such that $\|\partial_x^\alpha
(\rho-1)\|_{L^2(\mathbb R^n)}\approx
(1+t)^{-\frac{1+\lambda}{2}(\frac{n}{2}+|\alpha|)}$, and $\|\partial_x^\alpha
\boldsymbol u\|_{L^2(\mathbb R^n)}\approx
(1+t)^{-\frac{1+\lambda}{2}(\frac{n}{2}+|\alpha|)-\frac{1-\lambda}{2}}$, and
see how the under-damping effect influences the structure of the Euler system.
Different from the traditional view that the stronger damping usually makes the
solutions decaying faster, here surprisingly we recognize that the weaker
damping with $0\le\lambda<1$ enhances the faster decay for the solutions. The
adopted approach is the technical Fourier analysis and the Green function
method. The main difficulties caused by the time-dependent damping lie in
twofold: non-commutativity of the Fourier transform of the linearized operator
precludes explicit expression of the fundamental solution; time-dependent
evolution implies that the Green matrix $G(t,s)$ is not translation invariant,
i.e., $G(t,s)\ne G(t-s,0)$. We formulate the exact decay behavior of the Green
matrices $G(t,s)$ with respect to $t$ and $s$ for both linear wave equations
and linear hyperbolic system, and finally derive the optimal decay rates for
the nonlinear Euler system.",2006.00401v1
2022-08-17,Anti-parity-time symmetry hidden in a damping linear resonator,"Phase transition from the over-damping to under-damping states is a
ubiquitous phenomenon in physical systems. However, what kind of symmetry is
broken associated with this phase transition remains unclear. Here, we discover
that this phase transition is determined by an anti-parity-time
(anti-$\mathcal{PT}$) symmetry hidden in a single damping linear resonator,
which is significantly different from the conventional
anti-$\mathcal{PT}$-symmetric systems with two or more modes. We show that the
breaking of the anti-$\mathcal{PT}$ symmetry yields the phase transition from
the over-damping to under-damping states, with an exceptional point (EP)
corresponding to the critical-damping state. Moreover, we propose an
optomechanical scheme to show this anti-$\mathcal{PT}$ symmetry breaking by
using the optical spring effect in a quadratic optomechanical system. We also
suggest an optomechanical sensor with the sensitivity enhanced significantly
around the EPs for the anti-$\mathcal{PT}$ symmetry breaking. Our work unveils
the anti-$\mathcal{PT}$ symmetry hidden in damping oscillations and hence opens
up new possibilities for exploiting wide anti-$\mathcal{PT}$ symmetry
applications in single damping linear resonators.",2208.08187v2
2023-09-20,Evaluating Gilbert Damping in Magnetic Insulators from First Principles,"Magnetic damping has a significant impact on the performance of various
magnetic and spintronic devices, making it a long-standing focus of research.
The strength of magnetic damping is usually quantified by the Gilbert damping
constant in the Landau-Lifshitz-Gilbert equation. Here we propose a
first-principles based approach to evaluate the Gilbert damping constant
contributed by spin-lattice coupling in magnetic insulators. The approach
involves effective Hamiltonian models and spin-lattice dynamics simulations. As
a case study, we applied our method to Y$_3$Fe$_5$O$_{12}$, MnFe$_2$O$_4$ and
Cr$_2$O$_3$. Their damping constants were calculated to be $0.8\times10^{-4}$,
$0.2\times10^{-4}$, $2.2\times 10^{-4}$, respectively at a low temperature. The
results for Y$_3$Fe$_5$O$_{12}$ and Cr$_2$O$_3$ are in good agreement with
experimental measurements, while the discrepancy in MnFe$_2$O$_4$ can be
attributed to the inhomogeneity and small band gap in real samples. The
stronger damping observed in Cr$_2$O$_3$, compared to Y$_3$Fe$_5$O$_{12}$,
essentially results from its stronger spin-lattice coupling. In addition, we
confirmed a proportional relationship between damping constants and the
temperature difference of subsystems, which had been reported in previous
studies. These successful applications suggest that our approach serves as a
promising candidate for estimating the Gilbert damping constant in magnetic
insulators.",2309.11152v1
1996-12-10,Collisional matter-phase damping in Bose-condensed gas,"Collisional damping of the excitations in a Bose-condensed gas is
investigated over the wide range of energies and temperatures. Numerical
results for the damping rate are presented and a number of asymptotic and
interpolating expressions for it are derived.",9612086v1
2001-11-29,Tensor form of magnetization damping,"A tensor form of phenomenological damping is derived for small magnetization
motions. This form reflects basic physical relaxation processes for a general
uniformly magnetized particle or film. Scalar Landau-Lifshitz damping is found
to occur only for two special cases of system symmetry.",0111566v1
1999-07-28,An effective relaxation-time approach to collisionless quark-gluon plasma,"We present an effective relaxation-time theory to study the collisionless
quark-gluon plasma. Applying this method we calculate the damping rate to be of
order $g^2T$ and find plasmon scattering is the damping mechanism. The damping
for the transverse mode is stronger than the longitudinal one.",9907526v1
1999-11-16,Dynamical resummation and damping in the O(N) model,"A general real-time formalism is developed to resum the self-energy operator
of broken symmetry scalar field theories in form of self-consistent gap
equations for the spectral function. The solution of the equations is
approximated with finite lifetime quasi-particles. In the Landau damping rates
viscosity terms, analogous to gauge theories, appear, what leads to a finite
damping rate for the long wavelength Goldstone modes.",9911374v1
1993-03-24,On the Quantizations of the Damped Systems,"Based on a simple observation that a classical second order differential
equation may be decomposed into a set of two first order equations, we
introduce a Hamiltonian framework to quantize the damped systems. In
particular, we analyze the system of a linear damped harmonic oscillator and
demonstrate that the time evolution of the Schr\""odinger equation is
unambiguously determined.",9303137v1
2006-01-09,Energy decay for damped wave equations on partially rectangular domains,"We consider the wave equation with a damping term on a partially rectangular
planar domain, assuming that the damping is concentrated close to the
non-rectangular part of the domain. Polynomial decay estimates for the energy
of the solution are established.",0601195v1
2002-06-07,Resonant states and classical damping,"Using Koopman's approach to classical dynamical systems we show that the
classical damping may be interpreted as appearance of resonant states of the
corresponding Koopman's operator. It turns out that simple classical damped
systems give rise to discrete complex spectra. Therefore, the corresponding
generalized eigenvectors may be interpreted as classical resonant states.",0206009v1
2004-03-12,Factorization of damped wave equations with cubic nonlinearities,"The recent factorization scheme that we introduced for nonlinear polynomial
ODEs in math-ph/0401040 is applied to the interesting case of damped wave
equations with cubic nonlinearities. Traveling kink solutions are possible in
the plane defined by the kink velocity versus the damping coefficient only
along hyperbolas that are plotted herein",0403022v1
2002-08-07,Toward a Universal Model of Damping--Modified Coulomb Friction,"A modification of Coulomb's law of friction uses a variable coefficient of
friction that depends on a power law in the energy of mechanical oscillation.
Through the use of three different exponents: 0, 1/2 and 1; all commonly
encountered non-viscous forms of damping are accommodated. The nonlinear model
appears to yield good agreement with experiment in cases of surface, internal,
and amplitude dependent damping.",0208025v1
2002-12-19,Trapped particle bounds on stimulated scatter in the large k/kD regime,"In the strongly damped regime, the convective gain rate for stimulated
scatter varies inversely with the plasma wave damping rate. Electron trapping
effects reduce the damping but also lead to loss of resonance for large enough
amplitude waves. This leads to a gain rate bound and corresponding optimum
scattered light frequency and plasma wave amplitude.",0212071v1
2003-02-03,Oscillator damping with more than one mechanism of internal friction dissipation,"The author's modified Coulomb damping model has been generalized to
accommodate internal friction that derives from several dissipation mechanisms
acting simultaneously. Because of its fundamental nonlinear nature, internal
friction damping causes the quality factor Q of an oscillator in free-decay to
change in time. Examples are given which demonstrate reasonable agreement
between theory and experiment.",0302003v1
2003-02-15,Anisotropic Internal Friction Damping,"The mechanical damping properties of sheet polaroid material have been
studied with a physical pendulum. The polaroid samples were placed under the
knife-edges of the pendulum, which was operated in free-decay at a period in
the vicinity of 10 s. With the edges oriented parallel to the direction of the
long molecular chains in the polaroid, it was found that the damping was more
than 10% smaller than when oriented perpendicular to the chains.",0302055v1
2006-08-07,Study of the Damped Pendulum,"Experiments on the oscillatory motion of a suspended bar magnet throws light
on the damping effects acting on the pendulum. The viscous drag offered by air
was found the be the main contributor for slowing the pendulum down. The nature
and magnitude of the damping effects were shown to be strongly dependent on the
amplitude.",0608071v1
1995-02-27,Quantum Oscillator with Kronig-Penney Excitation in Different Regimes of Damping,"There are discussed the exact solution of the time--dependent Schr\""{o}dinger
equation for a damped quantum oscillator subject to a periodical frequency
delta--kicks describing squeezed states which are expressed in terms of
Chebyshev polynomials. The cases of strong and weak damping are investigated in
the frame of Caldirola--Kanai model.",9502023v1
2007-03-12,Quantum estimation of a damping constant,"We discuss an interferometric approach to the estimation of quantum
mechanical damping. We study specific classes of entangled and separable probe
states consisting of superpositions of coherent states. Based on the assumption
of limited quantum resources we show that entanglement improves the estimation
of an unknown damping constant.",0703091v2
2008-11-07,Asymptotic stability of the wave equation on compact surfaces and locally distributed damping - A sharp result,"This paper is concerned with the study of the wave equation on compact
surfaces and locally distributed damping. We study the case where the damping
is effective in a well-chosen subset of arbitrarily small measure.",0811.1190v1
2008-11-07,Uniform Stabilization of the wave equation on compact surfaces and locally distributed damping,"This paper is concerned with the study of the wave equation on compact
surfaces and locally distributed damping. We study the case where the damping
is effective on the complement of visible umbilical sets.",0811.1204v1
2010-11-20,Enhanced damping of ion acoustic waves in dense plasmas,"A theory for the ion acoustic wave damping in dense plasmas and warm dense
matter, accounting for the Umklapp process, is presented. A higher decay rate
compared to the prediction from the Landau damping theory is predicted for
high-Z dense plasmas where the electron density ranges from $10^{21}$ to $
10^{24} \mathrm{cm^{-3}}$ and the electron temperature is moderately higher
than the Fermi energy.",1011.4607v1
2012-06-26,On the $L^{2}$-critical nonlinear Schrödinger Equation with a nonlinear damping,"We consider the Cauchy problem for the $L^{2}$-critical nonlinear
Schr\""{o}dinger equation with a nonlinear damping. According to the power of
the damping term, we prove the global existence or the existence of finite time
blowup dynamics with the log-log blow-up speed for $\|\nabla u(t)\|_{L^2}$.",1206.6082v4
2012-10-12,Semi-linear wave equations with effective damping,"We study the Cauchy problem for the semi-linear damped wave equation in any
space dimension. We assume that the time-dependent damping term is effective.
We prove the global existence of small energy data solutions in the
supercritical case.",1210.3493v1
2012-12-08,A note on the lifespan of solutions to the semilinear damped wave equation,"This paper concerns estimates of the lifespan of solutions to the semilinear
damped wave equation. We give upper estimates of the lifespan for the
semilinear damped wave equation with variable coefficients in all space
dimensions.",1212.1772v3
2012-12-10,Strongly damped wave equation with exponential nonlinearities,"In this paper, we study the initial boundary value problem for the two
dimensional strong damped wave equation with exponentially growing source and
damping terms. We first show the well-posedness of this problem and then prove
the existence of the global attractor in $(H_{0}^{1}(\Omega)\cap
L^{\infty}(\Omega))\times L^{2}(\Omega)$.",1212.2180v2
2013-10-27,Exponential decay of solutions for the plate equation with localized damping,"In this paper, we give positive answer to the open question raised in [E.
Zuazua, Exponential decay for the semilinear wave equation with localized
damping in unbounded domains. J. Math. Pures Appl., 70 (1991) 513--529] on the
exponential decay of solutions for the semilinear plate equation with localized
damping.",1310.7243v3
2015-03-30,Damping to prevent the blow-up of the Korteweg-de Vries equation,"We study the behavior of the solution of a generalized damped KdV equation
$u_t + u_x + u_{xxx} + u^p u_x + \mathscr{L}_{\gamma}(u)= 0$. We first state
results on the local well-posedness. Then when $p \geq 4$, conditions on
$\mathscr{L}_{\gamma}$ are given to prevent the blow-up of the solution.
Finally, we numerically build such sequences of damping.",1503.08559v1
2015-06-16,Fast energy decay for wave equations with variable damping coefficients in the 1-D half line,"We derive fast decay estimates of the total energy for wave equations with
localized variable damping coefficients, which are dealt with in the one
dimensional half line $(0,\infty)$. The variable damping coefficient vanishes
near the boundary $x = 0$, and is effective critically near spatial infinity $x
= \infty$.",1506.04851v1
2015-11-16,Determination of intrinsic damping of perpendicularly magnetized ultrathin films from time resolved precessional magnetization measurements,"Magnetization dynamics are strongly influenced by damping. An effective
damping constant {\alpha}eff is often determined experimentally from the
spectral linewidth of the free induction decay of the magnetization after the
system is excited to its non-equilibrium state. Such an {\alpha}eff, however,
reflects both intrinsic damping as well as inhomogeneous broadening. In this
paper we compare measurements of the magnetization dynamics in ultrathin
non-epitaxial films having perpendicular magnetic anisotropy using two
different techniques, time-resolved magneto optical Kerr effect (TRMOKE) and
hybrid optical-electrical ferromagnetic resonance (OFMR). By using an external
magnetic field that is applied at very small angles to the film plane in the
TRMOKE studies, we develop an explicit closed-form analytical expression for
the TRMOKE spectral linewidth and show how this can be used to reliably extract
the intrinsic Gilbert damping constant. The damping constant determined in this
way is in excellent agreement with that determined from the OFMR method on the
same samples. Our studies indicate that the asymptotic high-field approach that
is often used in the TRMOKE method to distinguish the intrinsic damping from
the effective damping may result in significant error, because such high
external magnetic fields are required to make this approach valid that they are
out of reach. The error becomes larger the lower is the intrinsic damping
constant, and thus may account for the anomalously high damping constants that
are often reported in TRMOKE studies. In conventional ferromagnetic resonance
(FMR) studies, inhomogeneous contributions can be readily distinguished from
intrinsic damping contributions from the magnetic field dependence of the FMR
linewidth. Using the analogous approach, we show how reliable values of the
intrinsic damping can be extracted from TRMOKE.",1511.04802v1
2015-11-25,A Proposal of a Damping Term for the Relativistic Euler Equations,"We introduce a damping term for the special relativistic Euler equations in
$3$-D and show that the equations reduce to the non-relativistic damped Euler
equations in the Newtonian limit. We then write the equations as a symmetric
hyperbolic system for which local-in-time existence of smooth solutions can be
shown.",1511.08183v1
2016-01-27,Concatenated Codes for Amplitude Damping,"We discuss a method to construct quantum codes correcting amplitude damping
errors via code concatenation. The inner codes are chosen as asymmetric
Calderbank-Shor-Steane (CSS) codes. By concatenating with outer codes
correcting symmetric errors, many new codes with good parameters are found,
which are better than the amplitude damping codes obtained by any previously
known construction.",1601.07423v1
2016-03-29,Generalized damped Milne-Pinney equation and Chiellini method,"We adopt the Chiellini integrability method to find the solutions of various
generalizations of the damped Milne-Pinney equations. In particular, we find
the solution of the damped Ermakov-Painlev\'e II equation and generalized
dissipative Milne-Pinney equation.",1603.08747v2
2018-11-07,Slow-dissipation limit of the harmonic oscillator with general power-law damping,"An approximate solution is presented for simple harmonic motion in the
presence of damping by a force which is a general power-law function of the
velocity. The approximation is shown to be quite robust, allowing for a simple
way to investigate amplitude decay in the presence of general types of weak,
nonlinear damping.",1811.02953v2
2014-03-07,Landau damping in Sobolev spaces for the Vlasov-HMF model,"We consider the Vlasov-HMF (Hamiltonian Mean-Field) model. We consider
solutions starting in a small Sobolev neighborhood of a spatially homogeneous
state satisfying a linearized stability criterion (Penrose criterion). We prove
that these solutions exhibit a scattering behavior to a modified state, which
implies a nonlinear Landau damping effect with polynomial rate of damping.",1403.1668v2
2017-12-07,Damped wave equations on compact hyperbolic surfaces,"We prove exponential decay of energy for solutions of the damped wave
equation on compact hyperbolic surfaces with regular initial data as long as
the damping is nontrivial. The proof is based on a similar strategy as in
Dyatlov-Jin and in particular, uses the fractal uncertainty principle proved in
Bourgain-Dyatlov.",1712.02692v1
2018-09-10,Logarithmic Decay of a Wave Equation with Kelvin-Voigt Damping,"In this paper we analyze the long time behavior of a wave equation with local
Kelvin-Voigt Damping. Through introducing proper class symbol and
pseudo-differential calculus, we obtain a Carleman estimate, and then establish
an estimate on the corresponding resolvent operator. As a result, we show the
logarithmic decay rate for energy of the system without any geometric
assumption on the subdomain on which the damping is effective.",1809.03196v1
2019-09-25,Forced Coupled Duffing Oscillators with Nonlinear Damping: Resonance and Antiresonance,"In this work, we investigate resonance and antiresonance behaviour in forced
coupled Duffing oscillators with nonlinear damping. Further, we will analyse
the parameter dependence of the frequency response and stability. In the course
of all the analysis, emphasis shall be on how different damping mechanisms
contrast against each other.",1909.11390v1
2020-04-21,Damping rate limitations for transverse dampers in large hadron colliders,"The paper focuses on two issues important for design and operation of
bunch-by-bunch transverse damper in a very large hadron collider, where fast
damping is required to suppress beam instabilities and noise induced emittance
growth. The first issue is associated with kick variation along a bunch which
affects the damping of head-tail modes. The second issue is associated with
affect of damper noise on the instability threshold.",2004.10249v2
2012-05-16,Enhanced coupling design of a detuned damped structure for clic,"The key feature of the improved coupling design in the Damped Detuned
Structure (DDS) is focused on the four manifolds. Rectangular geometry slots
and rectangular manifolds are used. This results in a significantly stronger
coupling to the manifolds compared to the previous design. We describe the new
design together with its wakefield damping properties.",1205.3590v1
2018-03-20,Stability of the wave equations on a tree with local Kelvin-Voigt damping,"In this paper we study the stability problem of a tree of elastic strings
with local Kelvin-Voigt damping on some of the edges. Under the compatibility
condition of displacement and strain and continuity condition of damping
coefficients at the vertices of the tree, exponential/polynomial stability are
proved.",1803.07280v1
2021-02-01,Global existence for semilinear wave equations with scaling invariant damping in 3-D,"Global existence for small data Cauchy problem of semilinear wave equations
with scaling invariant damping in 3-D is established in this work, assuming
that the data are radial and the constant in front of the damping belongs to
$[1.5, 2)$. The proof is based on a weighted $L^2-L^2$ estimate for
inhomogeneous wave equation, which is established by interpolating between
energy estimate and Morawetz type estimate.",2102.00909v1
2021-08-17,Spectral enclosures for the damped elastic wave equation,"In this paper we investigate spectral properties of the damped elastic wave
equation. Deducing a correspondence between the eigenvalue problem of this
model and the one of Lam\'e operators with non self-adjoint perturbations, we
provide quantitative bounds on the location of the point spectrum in terms of
suitable norms of the damping coefficient.",2108.07676v1
2022-02-10,Stochastic optimal control for nonlinear damped network dynamics,"We present a stochastic optimal control problem for a tree network. The
dynamics of the network are governed by transport equations with a special
emphasis on the non-linear damping function. Demand profiles at the network
sinks are modelled by a stochastic differential equations. An explicit optimal
inflow into the network is determined and numerical simulations are presented
to show the effects for different choices of the non-linear damping.",2202.05114v1
2022-03-03,Conformal symmetry in damped Pais-Uhlenbeck oscillator,"Two Lagrangian formulations for describing of the damped harmonic oscillator
have been introduced by Bateman. For these models we construct higher
derivative generalization which enjoys the l-conformal Newton-Hooke symmetry.
The dynamics of generalized systems corresponds to the damped Pais-Uhlenbeck
oscillator for a particular choice of its frequencies.",2203.01651v1
2022-05-26,Ergodic results for the stochastic nonlinear Schrödinger equation with large damping,"We study the nonlinear Schr\""odinger equation with linear damping, i.e. a
zero order dissipation, and additive noise. Working in $R^d$ with d = 2 or d =
3, we prove the uniqueness of the invariant measure when the damping
coefficient is sufficiently large.",2205.13364v1
2022-10-31,An adaptive damped Newton method for strongly monotone and Lipschitz continuous operator equations,"We will consider the damped Newton method for strongly monotone and Lipschitz
continuous operator equations in a variational setting. We will provide a very
accessible justification why the undamped Newton method performs better than
its damped counterparts in a vicinity of a solution. Moreover, in the given
setting, an adaptive step-size strategy will be presented, which guarantees the
global convergence and favours an undamped update if admissible.",2210.17107v1
2022-11-19,Blow up and lifespan estimates for systems of semi-linear wave equations with damping and potential,"In this paper, we consider the semi-linear wave systems with
power-nonlinearities and a large class of space-dependent damping and
potential. We obtain the same blow-up regions and the lifespan estimates for
three types wave systems, compared with the systems without damping and
potential.",2211.10639v1
2023-08-10,Pathwise uniqueness for stochastic heat and damped equations with Hölder continuous drift,"In this paper, we prove pathwise uniqueness for stochastic differential
equations in infinite dimension. Under our assumptions, we are able to consider
the stochastic heat equation up to dimension $3$, the stochastic damped wave
equation in dimension $1$ and the stochastic Euler-Bernoulli damped beam
equation up to dimension $3$. We do not require that the so-called {\it
structure condition} holds true.",2308.05415v1
2023-10-30,Beliaev damping in Bose gas,"According to the Bogoliubov theory the low energy behaviour of the Bose gas
at zero temperature can be described by non-interacting bosonic quasiparticles
called phonons. In this work the damping rate of phonons at low momenta, the
so-called Beliaev damping, is explained and computed with simple arguments
involving the Fermi Golden Rule and Bogoliubov's quasiparticles.",2310.20070v1
2023-11-25,Energy scattering for the unsteady damped nonlinear Schrodinger equation,"We investigate the large time behavior of the solutions to the nonlinear
focusing Schr\""odinger equation with a time-dependent damping in the energy
sub-critical regime. Under non classical assumptions on the unsteady damping
term, we prove some scattering results in the energy space.",2311.14980v2
2007-01-08,Lorentz symmetry from Lorentz violation in the bulk,"We consider the mechanism of spontaneous symmetry breaking of a bulk vector
field to study signatures of bulk dimensions invisible to the standard model
confined to the brane. By assigning a non-vanishing vacuum expectation value to
the vector field, a direction is singled out in the bulk vacuum, thus breaking
the bulk Lorentz symmetry. We present the condition for induced Lorentz
symmetry on the brane, as phenomenologically required, noting that it is
related to the value of the observed cosmological constant.",0701191v1
2007-03-07,High Efficiency of Gamma-Ray Bursts Revisited,"Using the conservation of energy and momentum during collisions of any two
shells, we consider the efficiency of gamma-ray bursts by assuming that the
ejecta from the central engine are equally massive and have the same Lorentz
factors. We calculate the efficiency and the final Lorentz factor of the merged
whole shell for different initial diversities of Lorentz factors and for
different microscopic radiative efficiency. As a result, a common high
efficiency in the range of 0.1 to 0.9 is considerable, and a very high value
near 100% is also reachable if the diversity of the Lorentz factors is large
enough.",0703136v1
2003-05-22,The Lorentz force and superconductivity,"To change the velocity of an electron requires that a Lorentz force acts on
it, through an electric or a magnetic field. We point out that within the
conventional understanding of superconductivity electrons appear to change
their velocity in the absence of Lorentz forces. This indicates a fundamental
problem with the conventional theory of superconductivity. A hypothesis is
proposed to resolve this difficulty. This hypothesis is consistent with the
theory of hole superconductivity.",0305542v2
1997-06-04,Lorentz Invariance and the Cosmological Constant,"Non-trivial solutions in string field theory may lead to the spontaneous
breaking of Lorentz invariance and to new tensor-matter interactions. It is
argued that requiring the contribution of the vacuum expectation values of
Lorentz tensors to account for the vacuum energy up to the level that
$\Omega_{0}^{\Lambda} = 0.5$ implies the new interactions range is $\lambda
\sim 10^{-4} m$. These conjectured violations of the Lorentz symmetry are
consistent with the most stringent experimental limits.",9706012v1
2001-06-15,Composition of Lorentz Transformations in Terms of Their Generators,"Two-forms in Minkowski space-time may be considered as generators of Lorentz
transformations. Here, the covariant and general expression for the composition
law (Baker-Campbell-Hausdorff formula) of two Lorentz transformations in terms
of their generators is obtained. Every subalgebra of the Lorentz algebra of
such generators, up to one, may be generated by a sole pair of generators. When
the subalgebra is known, the above BCH formula for the two two-forms
simplifies. Its simplified expressions for all such subalgebras are also given.",0106052v1
2005-02-22,Modern tests of Lorentz invariance,"Motivated by ideas about quantum gravity, a tremendous amount of effort over
the past decade has gone into testing Lorentz invariance in various regimes.
This review summarizes both the theoretical frameworks for tests of Lorentz
invariance and experimental advances that have made new high precision tests
possible. The current constraints on Lorentz violating effects from both
terrestrial experiments and astrophysical observations are presented.",0502097v2
2005-03-09,Classical Gravitational Interactions and Gravitational Lorentz Force,"In quantum gauge theory of gravity, the gravitational field is represented by
gravitational gauge field. The field strength of gravitational gauge field has
both gravitational electric component and gravitational magnetic component. In
classical level, gauge theory of gravity gives out classical Newtonian
gravitational interactions in a relativistic form. Besides, it gives out
gravitational Lorentz force which is the gravitational force on a moving object
in gravitational magnetic field. The direction of gravitational Lorentz force
does not along that of classical gravitational Newtonian force. Effects of
gravitational Lorentz force should be detectable, and these effects can be used
to discriminate gravitational magnetic field from ordinary electromagnetic
magnetic field.",0503039v2
2004-01-13,Representations of the discrete inhomogeneous Lorentz group and Dirac wave equation on the lattice,"We propose the fundamental and two dimensional representation of the Lorentz
groups on a (3+1)-dimensional hypercubic lattice, from which representations of
higher dimensions can be constructed. For the unitary representation of the
discrete translation group we use the kernel of the Fourier transform. From the
Dirac representation of the Lorentz group (including reflections) we derive in
a natural way the wave equation on the lattice for spin 1/2 particles. Finally
the induced representation of the discrete inhomogeneous Lorentz group is
constructed by standard methods and its connection with the continuous case is
discussed.",0401019v1
1998-10-12,Hydrogen and Antihydrogen Spectroscopy for Studies of CPT and Lorentz Symmetry,"A theoretical study of possible signals for CPT and Lorentz violation arising
in hydrogen and antihydrogen spectroscopy is described. The analysis uses a
CPT- and Lorentz-violating extension of quantum electrodynamics, obtained from
a general Lorentz-violating extension of the minimal standard model with both
CPT-even and CPT-odd terms. Certain 1S-2S transitions and hyperfine Zeeman
lines exhibit effects at leading order in small CPT-violating couplings.",9810327v1
2001-04-15,Energy and Momentum of Oscillating Neutrinos,"It is shown that Lorentz invariance implies that in general flavor neutrinos
in oscillation experiments are superpositions of massive neutrinos with
different energies and different momenta. It is also shown that for each
process in which neutrinos are produced there is either a Lorentz frame in
which all massive neutrinos have the same energy or a Lorentz frame in which
all massive neutrinos have the same momentum. In the case of neutrinos produced
in two-body decay processes, there is a Lorentz frame in which all massive
neutrinos have the same energy.",0104148v1
2002-01-04,Scattering Cross Sections and Lorentz Violation,"To date, a significant effort has been made to adddress the Lorentz violating
standard model in low-energy systems, but little is known about the
ramifications for high-energy cross sections. In this talk, I discuss the
modified Feynman rules that result when Lorentz violation is present and give
the results of an explicit calculation for electron-positron annihilation into
two photons.",0201021v1
2003-08-14,The Lorentz and CPT violating effects on the Z\to l^+ l^- decay,"We study the Lorentz and CPT violating effects on the branching ratio BR, the
CPT violating asymmetry A_{CPT} and the ratio of the decay width, including
only the Lorentz violating effects, to the one obtained in the standard model,
for the flavor dependent part of the lepton flavor conserving Z\to l^+ l^-
(l=e,\mu,\tau) decay. The inclusion of the Lorentz and CPT violating effects to
the standard model contribution is too small to be detected, since the
corresponding coefficients are highly suppressed at the low energy scale.",0308151v2
2004-04-21,New Implications of Lorentz Violation,"In this proceedings, I summarize two recently discovered theoretical
implications that Lorentz violation has on physical systems. First, I discuss
new models for neutrino oscillations in which relatively simple combinations of
Lorentz-violating parameters can mimic the major features of the current
neutrino oscillation data. Second, I will present results on Yang-Mills
instantons in Lorentz-violating background fields. An explicit solution is
presented for unit winding number in SU(2).",0404178v1
2004-05-10,Compton Scattering in the Presence of Lorentz and CPT Violation,"We examine the process of Compton scattering, in the presence of a Lorentz-
and CPT-violating modification to the structure of the electron. We calculate
the complete tree-level contribution to the cross section; our result is valid
to all orders in the Lorentz-violating parameter. We find a cross section that
differs qualitatively from the Klein-Nishina result at small frequencies, and
we also encounter a previously undescribed complication that will arise in the
calculation of many Lorentz-violation cross sections: The Lorentz violation
breaks the spin degeneracy of the external states, so we cannot use a closure
relation to calculate the unpolarized cross section.",0405084v1
2005-01-13,Testing Lorentz Symmetry in Space,"Atomic clocks, masers, and other precision oscillators are likely to be
placed on the International Space Station and other satellites in the future.
These instruments will have the potential to measure Lorentz-violation
coefficients, and in particular may provide access to parts of the
Lorentz-violation coefficient space at levels not accessible with Earth-based
experiments. The basic issues are outlined in this proceedings.",0501113v1
2005-07-08,Non-abelian vector backgrounds with restored Lorentz invariance,"The influence of vector backgrounds with restored Lorentz invariance on
non-abelian gauge field theories is studied. Lorentz invariance is ensured by
taking the average over a Lorentz invariant ensemble of background vectors.
Like in the abelian case [hep-ph/0506210], the propagation of fermions is
suppressed over long distances. Contrary to the fermionic sector, pure gauge
configurations of the background suppress the long-distance propagation of the
bosons only partially, i.e. not beyond the leading contribution for a large
number of colours.",0507112v1
2006-02-27,"A Three-Flavor, Lorentz-Violating Solution to the LSND Anomaly","We investigate whether postulating the existence of Lorentz-violating,
CPT-conserving interactions allows three-neutrino solutions to the LSND anomaly
that are also consistent with all other neutrino data. We show that
Lorentz-violating interactions that couple only to one of the active neutrinos
have the right properties to explain all the data. The details of the data make
this solution unattractive. We find, for example, that a highly non-trivial
energy dependence of the Lorentz-violating interactions is required.",0602237v2
2006-03-17,Limits on Lorentz Violation from Synchrotron and Inverse Compton Sources,"We derive new bounds on Lorentz violations in the electron sector from
existing data on high-energy astrophysical sources. Synchrotron and inverse
Compton data give precisely complementary constraints. The best bound on a
specific combination of electron Lorentz-violating coefficients is at the 6 x
10^(-20) level, and independent bounds are available for all the
Lorentz-violating c coefficients at the 2 x 10^(-14) level or better. This
represents an improvement in some bounds by fourteen orders of magnitude.",0603138v1
2006-05-19,Lorentz Violation and Superpartner Masses,"We consider Lorentz violation in supersymmetric extensions of the standard
model. We perform a spurion analysis to show that, in the simplest natural
constructions, the resulting supersymmetry-breaking masses are tiny. In the
process, we argue that one of the strongest bounds on Lorentz violation in the
photon Lagrangian, which comes from the absence of birefringence from distant
astrophysical sources, does not apply when Lorentz violation is parametrized by
a single vector.",0605210v3
2006-10-24,Astrophysical Limits on Lorentz Violation for All Charged Species,"If Lorentz violation exists, it will affect the thresholds for pair creation
processes. Lorentz-violating operators that change the maximum velocities of
charged particles may increase or decrease the extinction rate of gamma-rays
moving through space. If the emissions from high-energy astrophysical sources
do not show any signs of anomalous absorption, this allows us to place bounds
on the Lorentz-violating c coefficients for multiple species of charged
particles. The bounds for a species of mass m_X based on observing photons at
an energy E can be O(m_X^2/E^2), which corresponds to limits at the
10^(-15)(m_X^2/m_e^2) level for the most energetic photons.",0610324v1
2007-03-27,Classification of Dimension 5 Lorentz Violating Interactions in the Standard Model,"We give a complete classification of mass dimension five
Lorentz-non-invariant interactions composed from the Standard Model fields,
using the effective field theory approach. We identify different classes of
Lorentz violating operators, some of which are protected against transmutation
to lower dimensions even at the loop level. Within each class of operators we
determine a typical experimental sensitivity to the size of Lorentz violation.",0703291v2
1994-07-28,Spontaneous Breakdown of the Lorentz Invariance and the Nambu-Goldstone Theorem,"In a class of three-dimensional abelian gauge theory the Lorentz invariance
is spontaneously broken by dynamical generation of a magnetic field. An
originally topologically massive photon becomes gapless, i.e. p_0=0 at {\vec
p}=0. Indeed, the photon is the Nambu-Goldstone boson associated with the
spontaneous breaking of the Lorentz invariance. Although symmetry generated by
two Lorentz boost generators is broken, there seems to appear only one physical
Nambu-Goldstone boson, namely a photon. We argue that the Ward identities in
the Nambu-Goldstone theorem are saturated by the photon pole.",9407188v1
1994-08-26,Spontaneous Breakdown of the Lorentz Invariance in Three-Dimensional Gauge Theories,"In a class of renormalizable three-dimensional abelian gauge theory the
Lorentz invariance is spontaneously broken by dynamical generation of a
magnetic field $B$. The true ground state resembles that of the quantum Hall
effect. An originally topologically massive photon becomes gapless, fulfilling
the role of the Nambu-Goldstone boson associated with the spontaneous breaking
of the Lorentz invariance. We give a simple explanation and a sufficient
condition for the spontaneous breaking of the Lorentz invariance with the aid
of the Nambu-Goldstone theorem. The decrease of the energy density by $B \not=
0$ is understood mostly due to the shift in zero-point energy of photons. For
PASCOS'94.",9408148v1
1995-03-27,NOTE ON MANIFEST LORENTZ AND GENERAL COORDINATE INVARIANCE IN DUALITY SYMMETRIC MODELS.,"We consider a generalization of a duality symmetric model proposed by Schwarz
and Sen. It is based on enlarging the model with a dynamical vector field being
a time-like component of a local Lorentz frame. This allows one to preserve the
manifest Lorentz invariance of the model in flat space--time. The presence of
this field is regarded as a relic of gravitational interaction which respects
the general coordinate invariance in curved space--time but breaks the local
Lorentz symmetry in tangent space down to its spatial subgroup.",9503182v1
1998-06-30,"Lorentz covariance, higher-spin superspaces and self-duality","Lorentz covariant generalisations of the notions of supersymmetry, superspace
and self-duality are discussed. The essential idea is to extend standard
constructions by allowing tangent vectors and coordinates which transform
according to more general Lorentz representations than solely the spinorial and
vectorial ones of standard lore. Such superspaces provide model configuration
spaces for theories of arbitrary spin fields. Our framework is an elegant one
for handling higher-dimensional theories in a manifestly SO(3,1) covariant
fashion. A further application is the construction of a hierarchy of solvable
Lorentz covariant systems generalising four-dimensional self-duality.",9806243v1
2001-11-28,Cosmological Background torsion limits from Lorentz violation,"Cosmological limits on Lorentz invariance breaking in Chern-Simons
$(3+1)-dimensional$ electrodynamics are used to place limits on torsion.
Birefrigence phenomena is discussed by using extending the propagation equation
to Riemann-Cartan spacetimes instead of treating it in purely Riemannian
spaces. The parameter of Lorentz violation is shown to be proportional to the
axial torsion vector which allows us to place a limit on cosmological
background torsion from the Lorentz violation constraint which is given by $
10^{-33} eV <|S^{\mu}| < 10^{-32} eV$ where $|S^{\mu}|$ is the axial torsion
vector.",0111251v1
2002-03-25,"Photons and Gravitons as Goldstone Bosons, and the Cosmological Constant","We reexamine a scenario in which photons and gravitons arise as Goldstone
bosons associated with the spontaneous breaking of Lorentz invariance. We study
the emergence of Lorentz invariant low energy physics in an effective field
theory framework, with non-Lorentz invariant effects arising from radiative
corrections and higher order interactions. Spontaneous breaking of the Lorentz
group also leads to additional exotic but weakly coupled Goldstone bosons,
whose dispersion relations we compute. The usual cosmological constant problem
is absent in this context: being a Goldstone boson, the graviton can never
develop a potential, and the existence of a flat spacetime solution to the
field equations is guaranteed.",0203221v1
2003-10-06,Lorentz-Violating Supergravity,"The standard forms of supersymmetry and supergravity are inextricably wedded
to Lorentz invariance. Here a Lorentz-violating form of supergravity is
proposed. The superpartners have exotic properties that are not possible in a
theory with exact Lorentz symmetry and microcausality. For example, the bosonic
sfermions have spin 1/2 and the fermionic gauginos have spin 1. The theory is
based on a phenomenological action that is shown to follow from a simple
microscopic and statistical picture.",0310039v2
2004-11-15,Space-Time Symmetries of Noncommutative Spaces,"We define a noncommutative Lorentz symmetry for canonical noncommutative
spaces. The noncommutative vector fields and the derivatives transform under a
deformed Lorentz transformation. We show that the star product is invariant
under noncommutative Lorentz transformations. We then apply our idea to the
case of actions obtained by expanding the star product and the fields taken in
the enveloping algebra via the Seiberg-Witten maps and verify that these
actions are invariant under these new noncommutative Lorentz transformations.
We finally consider general coordinate transformations and show that the metric
is undeformed.",0411147v2
2005-02-26,"Recent Results on N=2,4 Supersymmetry with Lorentz Symmetry Violating","In this work, we propose the N=2 and N=4 supersymmetric extensions of the
Lorentz-breaking Abelian Chern-Simons term. We formulate the question of the
Lorentz violation in 6 and 10 dimensions to obtain the bosonic sectors of
$N=2-$ and $N=4-$ supersymmetries, respectively. From this, we carry out an
analysis in N=1, D=4 superspace and, in terms of $N=1-$ superfields, we are
able to write down the N=2 and N=4 supersymmetric extensions of the
Lorentz-violating action term.",0502233v1
2005-04-27,The flight of the bumblebee: vacuum solutions of a gravity model with vector-induced spontaneous Lorentz symmetry breaking,"We study the vacuum solutions of a gravity model where Lorentz symmetry is
spontaneously broken once a vector field acquires a vacuum expectation value.
Results are presented for the purely radial Lorentz symmetry breaking (LSB),
radial/temporal LSB and axial/temporal LSB. The purely radial LSB result
corresponds to new black hole solutions. When possible, Parametrized
Post-Newtonian (PPN) parameters are computed and observational boundaries used
to constrain the Lorentz symmetry breaking scale.",0504215v1
2005-12-07,Radiatively Induced Lorentz-Violating Photon Masses,"We examine the radiative corrections to an extension of the standard model
containing a Lorentz-violating axial vector parameter. At second order in this
parameter, the photon self-energy is known to contain terms that violate gauge
invariance. Previously, this has been treated as a pathology, but it is also
possible to take the gauge noninvariant terms at face value. These terms then
make Lorentz-violating contributions to the photon mass, and directly measured
limits on the photon mass can be used to set bounds on the Lorentz violation at
better than the 10^-22 GeV level.",0512090v2
2006-05-03,Lorentz Violation and the Yukawa Potential,"We analyze Lorentz violations in the bosonic sector of a Yukawa-type quantum
field theory. The nonrelativistic potential may be determined to all orders in
the Lorentz violation, and we find that only specific types of modifications to
the normal Yukawa potential can be generated. The influence of this modified
potential on scattering and bounds states is calculated. These results could be
relevant to the search for new macroscopic forces, which may not necessarily be
Lorentz invariant.",0605044v1
2006-10-20,Compact Lorentz manifolds with local symmetry,"We prove a structure theorem for compact aspherical Lorentz manifolds with
abundant local symmetry. If M is a compact, aspherical, real-analytic, complete
Lorentz manifold such that the isometry group of the universal cover has
semisimple identity component, then the local isometry orbits in M are roughly
fibers of a fiber bundle. A corollary is that if M has a dense local isometry
orbit then M is locally homogeneous. The main result is analogous to a theorem
of Farb and Weinberger on compact aspherical Riemannian manifolds, and an
exposition of their arguments on rational cohomological dimension is included.
Some aspects of dynamics on Lorentz manifolds are also presented, including
totally geodesic, lightlike, codimension-one foliations associated to unbounded
sequences of isometries.",0610629v1
2005-07-21,Relativistic Spherical Functions on the Lorentz Group,"Matrix elements of irreducible representations of the Lorentz group are
calculated on the basis of complex angular momentum. It is shown that
Laplace-Beltrami operators, defined in this basis, give rise to Fuchsian
differential equations. An explicit form of the matrix elements of the Lorentz
group has been found via the addition theorem for generalized spherical
functions. Different expressions of the matrix elements are given in terms of
hypergeometric functions both for finite-dimensional and unitary
representations of the principal and supplementary series of the Lorentz group.",0507056v2
2007-01-12,Non-equilibrium Lorentz gas on a curved space,"The periodic Lorentz gas with external field and iso-kinetic thermostat is
equivalent, by conformal transformation, to a billiard with expanding
phase-space and slightly distorted scatterers, for which the trajectories are
straight lines. A further time rescaling allows to keep the speed constant in
that new geometry. In the hyperbolic regime, the stationary state of this
billiard is characterized by a phase-space contraction rate, equal to that of
the iso-kinetic Lorentz gas. In contrast to the iso-kinetic Lorentz gas where
phase-space contraction occurs in the bulk, the phase-space contraction rate
here takes place at the periodic boundaries.",0701024v1
2006-12-18,Three Questions on Lorentz Violation,"We review the basics of the two most widely used approaches to Lorentz
violation - the Stardard Model Extension and Noncommutative Field Theory - and
discuss in some detail the example of the modified spectrum of the synchrotron
radiation. Motivated by touching upon such a fundamental issue as Lorentz
symmetry, we ask three questions: What is behind the search for Lorentz
violation? Is String Theory a physical theory? Is there an alternative to
Supersymmetry?",0612171v1
1995-10-26,"EPR-Bell Nonlocality, Lorentz Invariance, and Bohmian Quantum Theory","We discuss the problem of finding a Lorentz invariant extension of Bohmian
mechanics. Due to the nonlocality of the theory there is (for systems of more
than one particle) no obvious way to achieve such an extension. We present a
model invariant under a certain limit of Lorentz transformations, a limit
retaining the characteristic feature of relativity, the non-existence of
absolute time resp. simultaneity. The analysis of this model exemplifies an
important property of any Bohmian quantum theory: the quantum equilibrium
distribution $\rho = |\psi |^2$ cannot simultaneously be realized in all
Lorentz frames of reference.",9510027v1
2001-10-01,"A non-local, Lorentz-invariant, hidden-variable interpretation of relativistic quantum mechanics based on particle trajectories","We demonstrate how to construct a lorentz-invariant, hidden-variable
interpretation of relativistic quantum mechanics based on particle
trajectories. The covariant theory that we propose employs a multi-time
formalism and a lorentz-invariant rule for the coordination of the space-time
points on the individual particle trajectories. In this way we show that there
is no contradiction between nonlocality and lorentz invariance in quantum
mechanics. The approach is illustrated for relativistic bosons, using a simple
model to discuss the individual non-locally correlated particle motion which
ensues when the wavefunction is entangled. A simple example of measurement is
described.",0110007v1
2003-08-28,Quantum Entanglement under Lorentz Boost,"In order to understand the characteristics of quantum entanglement of massive
particles under Lorentz boost, we first introduce a relevant relativistic spin
observable, and evaluate its expectation values for the Bell states under
Lorentz boost. Then we show that maximal violation of the Bell's inequality can
be achieved by properly adjusting the directions of the spin measurement even
in a relativistically moving inertial frame.
  Based on this we infer that the entanglement information is preserved under
Lorentz boost as a form of correlation information determined by the
transformation characteristic of the Bell state in use.",0308156v2
2007-05-08,Lorentz Space Estimates and Jacobian Convergence for the Ginzburg-Landau Energy with Applied Magnetic Field,"In this paper we continue the study of Lorentz space estimates for the
Ginzburg-Landau energy started in our previous paper, \cite{p1}. We focus on
getting estimates for the Ginzburg-Landau energy with external magnetic field
$h_{ex}$ in certain interesting regimes of $h_{ex}$. This allows us to show
that for configurations close to minimizers or local minimizers of the energy,
the vorticity mass of the configuration $(u,A)$ is comparable to the
$L^{2,\infty}$ Lorentz space norm of $\nabla_A u$. We also establish
convergence of the gauge-invariant Jacobians (vorticity measures) in the dual
of a function space defined in terms of Lorentz spaces.",0705.1114v1
2007-06-25,Field theory on $κ$--Minkowski space revisited: Noether charges and breaking of Lorentz symmetry,"This paper is devoted to detailed investigations of free scalar field theory
on $\kappa$-Minkowski space. After reviewing necessary mathematical tools we
discuss in depth the Lagrangian and solutions of field equations. We analyze
the spacetime symmetries of the model and construct the conserved charges
associated with translational and Lorentz symmetry. We show that the version of
the theory usually studied breaks Lorentz invariance in a subtle way: There is
an additional trans-Planckian mode present, and an associated conserved charge
(the number of such modes) is not a Lorentz scalar.",0706.3658v2
2007-07-03,Particle interference as a test of Lorentz-violating electrodynamics,"In Lorentz-violating electrodynamics a steady current (and similarly a static
charge) generates both static magnetic and electric fields. These induced
fields, acting on interfering particles, change the interference pattern. We
find that particle interference experiments are sensitive to small Lorentz
violating effects, and thus they can be used to improve current bounds on some
Lorentz-violating parameters.",0707.0343v1
2007-07-17,"Interpretation of relativistic, transverse, and longitudinal mass using the Lorentz transformation of reference time: Explanation of time dilation via spherical light clock","An interpretation of the inertial mass increase due to an object's velocity
which is derived from the theory of special relativity is discussed. A Lorentz
transformation of the reference time causes the inertial mass increase. It is
assumed that the real physical phenomenon that occurs is an expansion of the
reference time by a Lorentz transformation (that is, a dilation of time). Only
the reference time is assumed to be variant, which causes relativistic mass.
Time dilation is real. Relativistic mass originates in a Lorentz transformation
of reference time.",0707.2426v4
2007-10-31,The geometric phases in a background with Lorentz-symmetry violation,"We analyze the nonrelativistic quantum dynamics of a single neutral spin half
particle, with non-zero magnetic and electric dipole moments, moving in an
external electromagnetic field in presence of Lorentz symmetry violation
background. Also, we study the geometric phase for this model taking into
account the parameter that breaks the Lorentz symmetry. We investigate the
He-McKellar-Wilkens effect in this context and we verify that Lorentz violation
parameter contribute to increase the electric dipole moment of the particle.",0710.5858v2
2007-11-15,Spontaneous Lorentz Violation and Baryogenesis,"In the presence of background fields that spontaneously violate Lorentz
invariance, a matter-antimatter asymmetry can be generated even in thermal
equilibrium. In this paper we systematically investigate models of this type,
showing that either high-energy or electroweak versions of baryogenesis are
possible, depending on the dynamics of the Lorentz-violating fields. We
identify two scenarios of interest: baryogenesis from a weak-scale
pseudo-Nambu-Goldstone boson with intermediate-scale baryon-number violation,
and sphaleron-induced baryogenesis driven by a constant-magnitude vector with a
late-time phase transition.",0711.2519v2
2008-02-12,Tests of Lorentz symmetry using antihydrogen,"Signals of CPT and Lorentz violation are possible in the context of
spectroscopy using hydrogen and antihydrogen. We apply the Standard-Model
Extension, a broad framework for Lorentz breaking in physics, to various
transitions in the hydrogen and antihydrogen spectra. The results show an
unsuppressed effect in the transition between the upper two hyperfine sublevels
of the ground state of these systems. We also discuss related tests in Penning
traps, and recent work on Lorentz violation in curved spacetime.",0802.1736v1
2008-02-20,Lorentz symmetry violation and an Analog of Landau levels,"Within the context of Lorentz violating extended electrodynamics, we study an
analog of Landau quantization for a system where a neutral particle moves in
the presence of an electromagnetic field and a constant four-vector that breaks
Lorentz symmetry. The nonrelativistic Hamiltonian associated to this system is
obtained using the Foldy-Wouthuysen transformation for a Dirac spinor. The
degenerated energy spectrum is obtained for a time-like and a space-like
parameter Lorentz-breaking vector. The energy dependence of the cyclotron
rotation direction in terms of supersymmetric quantum mechanics is analyzed.",0802.2817v2
2008-09-27,Bounds on Lorentz and CPT Violation from the Earth-Ionosphere Cavity,"Electromagnetic resonant cavities form the basis of many tests of Lorentz
invariance involving photons. The effects of some forms of Lorentz violation
scale with cavity size. We investigate possible signals of violations in the
naturally occurring resonances formed in the Earth-ionosphere cavity.
Comparison with observed resonances places the first terrestrial constraints on
coefficients associated with dimension-three Lorentz-violating operators at the
level of 10^{-20} GeV.",0809.4801v1
2009-01-13,Disentangling Forms of Lorentz Violation With Complementary Clock Comparison Experiments,"Atomic clock comparisons provide some of the most precise tests of Lorentz
and CPT symmetries in the laboratory. With data from multiple such experiments
using different nuclei, it is possible to constrain new regions of the
parameter space for Lorentz violation. Relativistic effects in the nuclei allow
us to disentangle forms of Lorentz violation which could not be separately
measured in purely nonrelativistic experiments. The disentangled bounds in the
neutron sectors are at the 10^(-28) GeV level, far better than could be
obtained with any other current technique.",0901.1870v2
2009-10-06,Lorentz violation in three-family neutrino oscillation,"We analyze the consequences of Lorentz violation (LV) to three-generation
neutrino oscillation in the massless neutrino sector. We present a general
formalism of three-family neutrino oscillation with neutrino flavor states
being mixing states of energy eigenstates. It is also found that the mixing
parts could strongly depend on neutrino energy by special choices of Lorentz
violation parameters. By confronting with the existing experimental data on
neutrino oscillation, the upper bounds on LV parameters are derived. Because
the oscillation amplitude could vary with the neutrino energy, neutrino
experiments with energy dependence may test and constrain the Lorentz violation
scenario for neutrino oscillation.",0910.0897v1
2010-01-21,Factoring the Dispersion Relation in the Presence of Lorentz Violation,"We produce an explicit formula for the dispersion relation for the Dirac
Equation in the Standard Model Extension (SME) in the presence of Lorentz
violation. Our expression is obtained using a novel techniques which exploit
the algebra of quaternions. The dispersion relation is found to conveniently
factor in two special cases that each involve a mutually exclusive set of
non-vanishing Lorentz-violating parameters. This suggests that a useful
approach to studies of Lorentz-violating models is to split the parameter space
into two separate pieces, each of which yields a simple, tractable dispersion
relation that can be used for analysis.",1001.3839v1
2010-01-22,Deformation of the Bodies by the Result of Length Contraction: A new Approach to the Lorentz Contraction,"It has been more than a century since first Lorentz and later Einstein
explored relativistic events and still important consequences of that remains
unclear to everybody. The present study extensively focus on Lorentz (Length)
contraction phenomenon and takes a different approaches to explain how the
shrinking of the body appears if exists. We utilized two postulates of Special
Relativity that emphasizes constancy of speed of light and same physical laws
in any inertial frame. Finally, we propose Lorentz contraction exists in
different form through the shape of the accelerated body. The deformation of
its shape depends on the part where it is measured.",1001.3942v1
2010-07-06,Lorentz Symmetry Breaking in Quantum Electrodynamics,"In this dissertation, we study the implications generated by the Lorentz
breaking symmetry in quantum electrodynamics. We analyze fermions interacting
with an electromagnetic field in the contexts of quantum mechanics and make
radiative corrections. In quantum mechanics, the terms of the Lorentz breaking
symmetry were treated as perturbations to the Dirac equation, and their
expected values were obtained in a vacuum. In the radiative corrections, the
Lorentz breaking symmetry was introduced in this interaction for the
Chern-Simons like term could be induced in (3 +1) dimensions. We also discussed
the consequences generated by this term on the propagation speeds of classic
photons.",1007.0999v2
2010-07-30,Spontaneous Lorentz symmetry breaking in nonlinear electrodynamics,"We review some of the basic features and predictions of a gauge invariant
spontaneous Lorentz symmetry breaking model arising from the nonzero vacuum
expectation value of the electromagnetic tensor and leading to a nonlinear
electrodynamics. The model is stable in the small Lorentz invariance violation
approximation. The speed of light is independent of the frequency and one of
the propagating modes is highly anisotropic. The bound (Delta c)/c < 10^{-32}
is obtained for such anisotropy measured in perpendicular directions.",1008.0017v1
2010-08-02,Gravity Couplings in the Standard-Model Extension,"The Standard-Model Extension (SME) is an action-based expansion describing
general Lorentz violation for known matter and fields, including gravity. In
this talk, I will discuss the Lorentz-violating gravity couplings in the SME.
Toy models that match the SME expansion, including vector and two-tensor
models, are reviewed. Finally I discuss the status of experiments and
observations probing gravity coefficients for Lorentz violation.",1008.0345v1
2010-08-03,On the aether-like Lorentz-breaking action for the electromagnetic field,"We study the generation of aether-like Lorentz-breaking actions in three,
four and five dimensions via an appropriate Lorentz-breaking coupling of
electromagnetic and spinor fields. Special attention is given to the
four-dimensional case where we discuss the issue of ambiguities.",1008.0607v1
2010-08-22,Search for Lorentz Violation in a Short-Range Gravity Experiment,"An experimental test of the Newtonian inverse square law at short range has
been used to set limits on Lorentz violation in the pure gravity sector of the
Standard-Model Extension. On account of the planar test mass geometry,
nominally null with respect to inverse square forces, the limits derived for
the SME coefficients of Lorentz violation are on the order s ~ 10000.",1008.3670v1
2010-11-04,Lorentz-preserving fields in Lorentz-violating theories,"We identify a fairly general class of field configurations (of spins 0, 1/2
and 1) which preserve Lorentz invariance in effective field theories of Lorentz
violation characterized by a constant timelike vector. These fields
concomitantly satisfy the equations of motion yielding cubic dispersion
relations similar to those found earlier. They appear to have prospective
applications in inflationary scenarios.",1011.1206v2
2010-12-01,Traveling solitons in Lorentz-violating systems,"In this work we present a class of traveling solitons in Lorentz-violating
systems. In the case of Lorentz violating scenarios, it is usual to construct
static solitonic configurations. Here it is shown that it is possible to
construct some traveling solitons which, as it should be expected, can not be
mapped into a static configuration by means of Lorentz boosts due to its
explicit breaking. Furthermore, in the model studied, a complete set of
solutions is obtained. The solutions present a critical behavior controlled by
the choose of an arbitrary integration constant.",1012.0268v1
2011-08-10,Light-bending tests of Lorentz invariance,"Classical light bending is investigated for weak gravitational fields in the
presence of hypothetical local Lorentz violation. Using an effective field
theory framework that describes general deviations from local Lorentz
invariance, we derive a modified deflection angle for light passing near a
massive body. The results include anisotropic effects not present for spherical
sources in General Relativity as well as Weak Equivalence Principle violation.
We develop an expression for the relative deflection of two distant stars that
can be used to analyze data in past and future solar-system observations. The
measurement sensitivities of such tests to coefficients for Lorentz violation
are discussed.",1108.2071v1
2011-09-21,Overview of Lorentz Violation in Neutrinos,"A general introduction to Lorentz and CPT violation is presented. The
observable effects of the breakdown of such fundamental symmetries in neutrinos
are outlined and different experimental searches of some of the key signals of
Lorentz violation are discussed. A novel powerful method to study
model-independent neutrino oscillations is reviewed and then used to illustrate
a new global model of neutrino oscillations based on Lorentz violation
consistent with atmospheric, accelerator, reactor, and solar neutrino data.",1109.4620v1
2011-09-29,New theory of Lorentz violation from a general principle,"We report that a general principle of physical independence of mathematical
background manifolds brings a replacement of common derivative operators by
co-derivative ones. Then we obtain a new Lagrangian for the ordinary minimal
standard model with supplementary terms containing the Lorentz invariance
violation information measured by a new matrix, denoted as the Lorentz
invariance violation matrix. We thus provide a new fundamental theory to study
Lorentz invariance violation effects consistently and systematically.",1109.6387v2
2012-02-27,Lorentz Violation and the Higgs Mechanism,"We consider scalar quantum electrodynamics in the Higgs phase and in the
presence of Lorentz violation. Spontaneous breaking of the gauge symmetry gives
rise to Lorentz-violating gauge field mass terms. These may cause the
longitudinal mode of the gauge field to propagate superluminally. The theory
may be quantized by the Faddeev-Popov procedure, although the Lagrangian for
the ghost fields also needs to be Lorentz violating.",1202.5993v2
2012-03-15,He-McKellar-Wilkens effect and Scalar Aharonov-Bohm effect for a neutral particle based on the Lorentz symmetry violation,"In this contribution, we discuss the He-McKellar-Wilkens effect and the
Scalar Aharonov-Bohm effect for neutral particles based on the Lorentz symmetry
violation background, by showing that the background of the Lorentz symmetry
violation yields abelian quantum phases for a neutral particle. We also study
the nonrelativistic bound states for a neutral particle interacting with a
Coulomb-like potential based on the Lorentz symmetry violation background given
by a fixed vector field parallel to the radial direction.",1203.3407v2
2012-06-26,Deformed Bubbles and Lorentz Invariance in Vacuum Decay,"Recently, questions have been raised about the role of Lorentz invariance in
false vacuum decay. It has been argued that infinities may arise in an
integration over Lorentz-boosted final states. This suggestion motivates a
Minkowski-space analysis of the decay rate. We attempt to illuminate features
of the amplitude computation, and argue that the total rate including
excitations is both finite and Lorentz invariant.",1206.5880v1
2012-08-02,Lorentz invariance in heavy particle effective theories,"Employing induced representations of the Lorentz group (Wigner's little group
construction), formalism for constructing heavy particle effective Lagrangians
is developed, and Lagrangian constraints enforcing Lorentz invariance of the S
matrix are derived. The relationship between Lorentz invariance and
reparameterization invariance is established and it is shown why a standard
ansatz for implementing reparameterization invariance in heavy fermion
effective Lagrangians breaks down at order 1/M^4. Formalism for fields of
arbitrary spin and for self-conjugate fields is presented, and the extension to
effective theories of massless fields is discussed.",1208.0601v1
2012-09-17,Lorentz and CPT violations in Finsler spacetime,"Standard model with intrinsic Lorentz and CPT violations is proposed in a
Finsler geometric framework. We present explicitly Lorentz and CPT--breaking
Lagrangians of the matter fields and the gauge fields in locally Minkowski
spacetime. The Lorentz invariance violation is found to be originated from the
spacetime background deviating from the Minkowski one. Similarly, the CPT
violation is determined by the behaviors of the locally Minkowski metric under
the parity and time reversal operations. To help understanding phenomenologies,
we compare the Finslerian model with the standard--model extension (SME) term
by term at a first order approximation.",1209.3574v2
2013-01-02,On the Lorentz Factor of Superluminal Sources,"We investigate the properties of features seen within superluminal sources
often referred to as components. Our result indicates a fairly strong
correlation of r=0.6 for quasars, r=0.4 for galaxies, and r=0.8 for BL Lac
objects in our sample between component sizes and distances from the stationary
core. Assumption of free adiabatic expanding plasma enabled us to constrain in
general the Lorentz factor for superluminal sources. Ourestimated Lorentz
factor of 7 - 17 for quasars, 6 - 13 for galaxies and 4- 9 for BL Lac objects
indicate that BL Lac have the lowest range of Lorentz factor.",1301.0248v1
2013-02-11,Neutrino Beam Constraints on Flavor-Diagonal Lorentz Violation,"Breaking of isotropy and Lorentz boost invariance in the dynamics of
second-generation leptons would lead to direction-dependent changes in the
lifetimes of charged pions. This would make the intensity of a neutrino beam
produced via pion decay a function of the beam orientation. The experimental
signature of this phenomenon--sidereal variations in the event rate at a
downstream neutrino detector--has already been studied, in searches for
Lorentz-violating neutrino oscillations. Existing analyses of MINOS near
detector data can be used to constrain the flavor-diagonal Lorentz violation
coefficients affecting muon neutrino speeds at roughly the 10^(-5) level.",1302.2598v3
2013-02-20,Lorentz Violation in the Higgs Sector and Noncommutative Standard Model,"The noncommutative standard model apparently violates the Lorentz symmetry.
We compare the Lorentz violating terms in the Higgs sector of the
noncommutative standard model with their counterparts in the standard model
extension. We show that the Lorentz violating parameters in the Higgs sector
can be expressed directly in terms of the noncommutative parameter without any
background field. The absence of the background field enhances the obtained
bounds on the noncommutative parameter from the standard model extension.",1302.5023v1
2013-04-17,Relativistic Landau-He-McKellar-Wilkens quantization and relativistic bound states solutions for a Coulomb-like potential induced by the Lorentz symmetry breaking effects,"In this work, we discuss the relativistic Landau-He-McKellar-Wilkens
quantization and relativistic bound states solutions for a Dirac neutral
particle under the influence of a Coulomb-like potential induced by the Lorentz
symmetry breaking effects. We present new possible scenarios of studying
Lorentz symmetry breaking effects by fixing the space-like vector field
background in special configurations. It is worth mentioning that we use the
criterion for studying the violation of Lorentz symmetry is that the gauge
symmetry should be preserved.",1304.4830v1
2013-07-30,The influence of Lorentz violation on UHE photon detection,"We show that violation of the Lorentz symmetry in quantum electrodynamics can
suppress the rates of the interactions crucial for the formation of
photon-induced air showers, such as pair production on nuclei and in the
geomagnetic field. As a consequence, the allowed region in the space of
Lorentz-violating parameters will be seriously restricted if several photons
with energies $\gtrsim\,10^{19}\, {eV}$ are detected.",1307.8027v1
2013-07-31,Lorentz Violation in Top-Quark Physics,"Lorentz and CPT violation can affect the rates for $t$-$\ol t$ production and
decay. The Lorentz-violating coefficients in the Standard-Model Extension
responsible for modifying the top-quark events have recently been bounded by
the D0 Collaboration. To extend the analysis to the LHC the calculations need
to be extended to include the gluon fusion production mechanism. Some of the
first results of this program were presented at the Meeting.",1307.8350v1
2014-02-11,Information under Lorentz transformation,"A general form of a two-qubit system is obtained under the effect of Lorentz
transformation. We investigate extensively some important classes in the
context of quantum information. It is shown Lorentz transformation causes a
decay of entanglement and consequently information loses. On the other hand, it
generates entangled states between systems prepared initially in a separable
states. The partial entangled states are more robust under Lorentz
transformation than maximally entangled states. Therefore the rate of
information lose is larger for maximum entangled states compared with that for
partially entangled states.",1402.2605v1
2014-04-11,Seeking Lorentz Violation from the Higgs,"The recently discovered Higgs particle with a mass near $126$ GeV presents
new opportunities to explore Lorentz violation. Ultra-high-energy cosmic rays
are one of the most sensitive testing grounds for Lorentz symmetry, and can be
used to seek for and limit departures from Lorentz invariance in the Higgs
sector. If the Higgs were to have a super- or sub-luminal maximal speed both
Higgs and weak interaction physics would be modified. Consideration of such
modifications allow us to constrain the Higgs maximal velocity to agree with
that of other Standard Model particles to parts in $10^{14}$.",1404.3185v1
2014-04-17,Discrete Lorentz covariance for Quantum Walks and Quantum Cellular Automata,"We formalize a notion of discrete Lorentz transforms for Quantum Walks (QW)
and Quantum Cellular Automata (QCA), in (1 + 1)-dimensional discrete spacetime.
The theory admits a diagrammatic representation in terms of a few local,
circuit equivalence rules. Within this framework, we show the first-order-only
covariance of the Dirac QW. We then introduce the Clock QW and the Clock QCA,
and prove that they are exactly discrete Lorentz covariant. The theory also
allows for non-homogeneous Lorentz transforms, between non-inertial frames.",1404.4499v1
2014-04-30,Limits on Lorentz violation from charged-pion decay,"Charged-pion decay offers many opportunities to study Lorentz violation.
Using an effective field theory approach, we study Lorentz violation in the
lepton, W-boson, and quark sectors and derive the differential pion-decay rate,
including muon polarization. Using coordinate redefinitions we are able to
relate the first-generation quark sector, in which no bounds were previously
reported, to the lepton and W-boson sector. This facilitates a tractable
calculation, enabling us to place bounds on the level of $10^{-4}$ on
first-generation quark parameters. Our expression for the pion-decay rate can
be used to constrain Lorentz violation in future experiments.",1404.7629v1
2014-12-15,Global Lorentz and Lorentz-Morrey estimates below the natural exponent for quasilinear equations,"Lorentz and Lorentz-Morrey estimates are obtained for gradients of very weak
solutions to quasilinear equations of the form $$\text{div}\,\mathcal{A}(x,
\nabla u)=\text{div}\, |{\bf f}|^{p-2}{\bf f},$$ where
$\text{div}\,\mathcal{A}(x, \nabla u)$ is modelled after the $p$-Laplacian,
$p>1$. The estimates are global over bounded domains that satisfy a mild
exterior uniform thickness condition that involves the $p$-capacity. The vector
field datum ${\bf f}$ is allowed to have low degrees of integrability and thus
solutions may not have finite $L^p$ energy. A higher integrability result at
the boundary of the ground domain is also obtained for infinite energy
solutions to the associated homogeneous equations.",1412.4833v1
2015-05-22,What do we know about Lorentz Symmetry?,"Precision tests of Lorentz symmetry have become increasingly of interest to
the broader gravitational and high-energy physics communities. In this talk,
recent work on violations of local Lorentz invariance in gravity is discussed,
including recent analysis constraining Lorentz violation in a variety of
gravitational tests. The arena of short-range tests of gravity is highlighted,
demonstrating that such tests are sensitive to a broad class of unexplored
signals that depend on sidereal time and the geometry of the experiment.",1505.05975v1
2015-08-19,Lorentz symmetry breaking effects on relativistic EPR correlations,"Lorentz symmetry breaking effects on relativistic EPR
(Einstein-Podolsky-Rosen) correlations are discussed. From the modified Maxwell
theory coupled to gravity, we establish a possible scenario of the Lorentz
symmetry violation and write an effective metric for the Minkowski spacetime.
Then, we obtain the Wigner rotation angle via the Fermi-Walker transport of
spinors and consider the WKB ((Wentzel-Kramers-Brillouin) approximation in
order to study the influence of Lorentz symmetry breaking effects on the
relativistic EPR correlations.",1508.04662v1
2015-08-23,Bohnenblust-Hille inequalities for Lorentz spaces via interpolation,"We prove that the Lorentz sequence space $\ell_{\frac{2m}{m+1},1}$ is, in
a~precise sense, optimal among all symmetric Banach sequence spaces satisfying
a Bohnenblust-Hille type inequality for $m$-linear forms or $m$-homogeneous
polynomials on $\mathbb{C}^n$. Motivated by this result we develop methods for
dealing with subtle Bohnenblust-Hille type inequalities in the setting of
Lorentz spaces. Based on an interpolation approach and the Blei-Fournier
inequalities involving mixed type spaces, we prove multilinear and polynomial
Bohnenblust-Hille type inequalities in Lorentz spaces with subpolynomial and
subexponential constants. Improving a remarkable result of
Balasubramanian-Calado-Queff\'elec, we show an application to the theory of
Dirichlet series.",1508.05554v1
2015-09-01,On the decoupling of heavy states in higher-derivative supersymmetric field theories,"We study the problem of decoupling of heavy chiral superfields in
four-dimensional $N=1$ supersymmetric field theories with Lorentz-invariant and
Lorentz-violating higher-derivative terms. We demonstrate that the earlier
found effect of large logarithmic quantum corrections, due to heavy chiral
superfields, takes place not only if the theory possesses quantum divergences,
but also for essentially finite theories involving higher derivative terms,
both Lorentz-invariant and Lorentz-breaking ones.",1509.00251v2
2015-11-02,Lorentz and CPT Violation in Top-Quark Production,"Signals for Lorentz and CPT violation can appear in a wide range of
experiments including hadron colliders like the LHC. We present a calculation
of the Lorentz-violating cross section for top-quark pair production via gluon
fusion. This process dominates at the LHC, and analysis of LHC data should
permit sharpening the constraints on top-quark Lorentz violation obtained
recently by the D0 Collaboration. We also present a separate calculation of
single-top production, which is sensitive to CPT violation. Data from the LHC
can be used to measure coefficients for CPT violation in the top-quark sector
for the first time.",1511.00630v1
2015-11-19,Sharp Lorentz estimates for dyadic-like maximal operators and related Bellman functions,"We precisely evaluate Bellman type functions for the dyadic maximal opeator
on $R^n$ and of maximal operators on martingales related to local Lorentz type
estimates. Using a type of symmetrization principle, introduced for the dyadic
maximal operator in earlier works of the authors we precisely evaluate the
supremum of the Lorentz quasinorm of the maximal operator on a function $\phi$
when the integral of $\phi$ is fixed and also the same Lorentz quasinorm of
$\phi$ is fixed. Also we find the corresponding supremum when the integral of
$\phi$ is fixed and several weak type conditions are given.",1511.06112v1
2016-01-19,Traces of Lorentz symmetry breaking in a Hydrogen atom at ground state,"Some traces of a specific Lorentz symmetry breaking scenario in the ground
state of the Hydrogen atom are investigated. It is used standard
Rayleigh-Schr\""odinger perturbation theory in order to obtain the corrections
to the the ground state energy and wave function. It is shown that an induced
four-pole moment arises, due to the Lorentz symmetry breaking. The model
considered is the one studied in reference Eur. Phys. J. C {\bf 74}, 2937
(2014), where the Lorentz symmetry is broken in the electromagnetic sector.",1601.04784v1
2016-02-15,Testing local Lorentz invariance with gravitational waves,"The effects of local Lorentz violation on dispersion and birefringence of
gravitational waves are investigated. The covariant dispersion relation for
gravitational waves involving gauge-invariant Lorentz-violating operators of
arbitrary mass dimension is constructed. The chirp signal from the
gravitational-wave event GW150914 is used to place numerous first constraints
on gravitational Lorentz violation.",1602.04782v1
2016-07-13,Lorentz gauge quantization in synchronous coordinates,"It has been shown that the Gupta-Bleuler method of quantization can be used
to impose the Lorentz gauge condition in static space-times but not in
cosmological space-times. This implies that the Gupta-Bleuler approach fails in
general in non-static space-times. More recently, however, the Dirac method of
quantizing constrained dynamical systems has been successfully employed to
impose the Lorentz gauge in conformally flat space-times. In this paper we
generalize this result by using Dirac's method to impose the Lorentz gauge in a
general space-time region where the metric is expressed in synchronous
coordinates.",1607.03873v1
2016-07-22,Prospects for Testing Lorentz and CPT Invariance in the Top-Quark Sector,"We present how to further the search for Lorentz and CPT violation in the
top-quark sector after the first measurement in this sector by D0. We compute
the Lorentz-violating matrix element for top pair production via gluon fusion,
which allows a similar but more precise measurement at the LHC. For CPT
violation, we analyze single-top production, derive the modified matrix
elements, and predict possible signals.",1607.06786v1
2016-07-24,Search for Lorentz Violation using Short-Range Tests of Gravity,"Experimental tests of the newtonian inverse square law at short range, one at
Indiana University and the other at the Huazhong University of Science and
Technology, have been used to set limits on Lorentz violation in the pure
gravity sector of the nonminimal Standard-Model Extension. In the
nonrelativistic limit, the constraints derived for the 14 independent SME
coefficients for Lorentz violation acting simultaneously are of order $10^{-9}$
m$^{2}$.",1607.07092v1
2016-10-28,Lorentz Violation in Deep Inelastic Electron-Proton Scattering,"Lorentz violation in the quark sector induces a sidereal time dependence in
electron-proton, proton-antiproton and proton-proton cross sections. At high
energies nonperturbative effects are buried in universal nucleon parton
distribution functions and Lorentz violating effects are calculable in
perturbation theory. We focus on deep inelastic electron-proton scattering data
collected from ZEUS and H1 at HERA and show that a sideral time analysis of
these events is able to set strong constraints on most of the coefficients we
consider.",1610.09318v1
2017-08-01,Discrete Lorentz symmetry and discrete time translational symmetry,"The Lorentz symmetry and the space and time translational symmetry are
fundamental symmetries of nature. Crystals are the manifestation of the
continuous space translational symmetry being spontaneously broken into a
discrete one. We argue that, following the space translational symmetry, the
continuous Lorentz symmetry should also be broken into a discrete one, which
further implies that the continuous time translational symmetry is broken into
a discrete one. We deduce all the possible discrete Lorentz and discrete time
translational symmetries in 1+1-dimensional spacetime, and show how to build a
field theory or a lattice field theory that has these symmetries.",1708.00924v2
2017-08-28,Coulomb-type interaction under Lorentz symmetry breaking effects,"Based on models of confinement of quarks, we analyse a relativistic scalar
particle subject to a scalar potential proportional to the inverse of the
radial distance and under the effects of the violation of the Lorentz symmetry.
We show that the effects of the Lorentz symmetry breaking can induced a
harmonic-type potential. Then, we solve the Klein-Gordon equation analytically
and discuss the influence of the background of the violation of the Lorentz
symmetry on the relativistic energy levels.",1708.09024v1
2018-04-23,"Lorentz violation, Möller scattering and finite temperature","Lorentz and CPT symmetries may be violated in new physics that emerges at
very high energy scale, i.e., at the Planck scale. The differential cross
section of the M\""oller scattering, due to Lorentz violation at finite
temperature is calculated. Lorentz-violating effects emerge from an interaction
vertex due to a CPT-odd nonminimal coupling in the covariant derivative. The
finite temperature effects are determined using the Thermo Field Dynamics (TFD)
formalism.",1804.08566v1
2013-08-15,Remarks on Finsler Geometry and Lorentz Violation,"The physics of classical particles in a Lorentz-breaking spacetime has
numerous features resembling the properties of Finsler geometry. In particular,
the Lagrange function plays a role similar to that of a Finsler structure
function. A summary is presented of recent results, including new calculable
Finsler structures based on Lagrange functions appearing in the
Lorentz-violation framework known as the Standard-Model Extension.",1308.3442v1
2013-08-26,Limits on Lorentz violation from forbidden beta decays,"Forbidden (slow) beta decays offer new opportunities to test the invariance
of the weak interaction under Lorentz transformations. Within a general
effective field theory framework we analyze and reinterpret the only two
relevant experiments, performed in the 1970s, dedicated to search for a
preferred direction in space in first- and second-forbidden beta decays. We
show that the results of these experiments put strong and unique limits on
Lorentz violation, and in particular on the presence of several interactions in
the modern Lorentz-violating Standard Model extension. We discuss prospects to
improve on these limits.",1308.5570v1
2013-08-30,"Macroscopic Objects, Intrinsic Spin, and Lorentz Violation","The framework of the Standard-Model Extension (SME) provides a relativistic
quantum field theory for the study of Lorentz violation. The classical,
nonrelativistic equations of motion can be extracted as a limit that is useful
in various scenarios. In this work, we consider the effects of certain SME
coefficients for Lorentz violation on the motion of macroscopic objects having
net intrinsic spin in the classical, nonrelativistic limit.",1308.6743v1
2014-03-24,Kinematical Lorentz-symmetry tests at particle colliders,"Violations of Lorentz symmetry are typically associated with modifications of
one-particle dispersion relations. The physical effects of such modifications
in particle collisions often grow with energy, so that ultrahigh-energy cosmic
rays provide an excellent laboratory for measuring such effects. In this talk
we argue that collisions at particle colliders, which involve much smaller
energies, can nevertheless yield competitive constraints on Lorentz breaking.",1403.6051v1
2014-03-29,Lorentz violation and Condensed Matter Physics,"We present heuristic arguments that hint to a possible connection of Lorentz
violation with observed phenomenon in condensed matter physics. Various
references from condensed matter literature are cited where operators in the
Standard Model Extension appear to be enhanced. Furthermore, we consider the
Levy-Leblond equation, which is the analogue of Dirac equation in
non-relativistic quantum mechanics. We show that we can obtain the Levy-Leblond
equation by adding enhanced Lorentz violating operators to the Dirac equation.
Based on these observations, we propose that Lorentz violation exhibits itself
in non-relativistic quantum mechanics.",1403.7622v2
2016-11-01,The Cosmic Microwave Background And Pseudo-Nambu-Goldstone Bosons: Searching For Lorentz Violations In The Cosmos,"One of the most powerful probes of new physics is the polarized Cosmic
Microwave Background (CMB). The detection of a nonzero polarization angle
rotation between the CMB surface of last scattering and today could provide
evidence of Lorentz-violating physics. The purpose of this paper is twofold.
First we review one popular mechanism for polarization rotation of CMB photons:
the pseudo-Nambu-Goldstone boson. Second, we propose a method to use the
Polarbear experiment to constrain Lorentz-violating physics in the context of
the Standard-Model Extension, a framework to standardize a large class of
potential Lorentz-violating terms in particle physics.",1611.00418v1
2008-07-16,Testing Lorentz Invariance Violation with WMAP Five Year Data,"We consider different renormalizable models of Lorentz invariance violation.
We show that the limits on birefringence of the propagation of cosmic microwave
background photons from the five year data of the Wilkinson microwave
anisotropy probe (WMAP) can be translated into a limit of Lorentz symmetry
violation. The obtained limits on Lorentz invariance violation are stronger
than other published limits. We also cast them in terms of limits on a
birefringent effective photo ""mass"" and on a polarization dependence of the
speed of light.",0807.2593v3
2009-12-24,Lorentz violation with an antisymmetric tensor,"Field theories with spontaneous Lorentz violation involving an antisymmetric
2-tensor are studied. A general action including nonminimal gravitational
couplings is constructed, and features of the Nambu-Goldstone and massive modes
are discussed. Minimal models in Minkowski spacetime exhibit dualities with
Lorentz-violating vector and scalar theories. The post-newtonian expansion for
nonminimal models in Riemann spacetime involves qualitatively new features,
including the absence of an isotropic limit. Certain interactions producing
stable Lorentz-violating theories in Minkowski spacetime solve the
renormalization-group equations in the tadpole approximation.",0912.4852v1
2012-01-14,Massive photons and Lorentz violation,"All quadratic translation- and gauge-invariant photon operators for Lorentz
breakdown are included into the Stueckelberg Lagrangian for massive photons in
a generalized \xi-gauge. The corresponding dispersion relation and tree-level
propagator are determined exactly, and some leading-order results are derived.
The question of how to include such Lorentz-violating effects into a
perturbative quantum-field expansion is addressed. Applications of these
results within Lorentz-breaking quantum field theories include the
regularization of infrared divergences as well as the free propagation of
massive vector bosons.",1201.3045v1
2013-09-07,Partial generalizations of some Conjectures in locally symmetric Lorentz spaces,"In this paper, first we give a notion for linear Weingarten spacelike
hypersurfaces with $P+aH=b$ in a locally symmetric Lorentz space $L_{1}^{n+1}$.
Furthermore, we study complete or compact linear Weingarten spacelike
hypersurfaces in locally symmetric Lorentz spaces $L_{1}^{n+1}$ satisfying some
curvature conditions. By modifying Cheng-Yau's operator $\square$ given in
{\cite{ChengYau77}}, we introduce a modified operator $L$ and give new
estimates of $L(nH)$ and $\square(nH)$ of such spacelike hypersurfaces.
Finally, we give partial generalizations of some conjectures in locally
symmetric Lorentz spaces $L_{1}^{n+1}$.",1309.1840v1
2013-09-30,Lorentz violation in a uniform newtonian gravitational field,"Lorentz invariance is one of the fundamental principles of physics, and, as
such, it must be experimentally tested. The purpose of this work is to obtain,
within the Standard-Model Extension, the dynamics of a Lorentz-violating spinor
in a uniform newtonian gravitational field. This is achieved by treating the
spinor as a test particle and introducing the gravitational field through a
uniformly accelerated observer. The nonrelativistic hamiltonian is obtained and
some experimental consequences are discussed. One unexpected outcome of this
work is that the gravitational field helps disentangling bounds on coefficients
for Lorentz violation.",1309.7972v2
2017-10-04,Triebel-Lizorkin-Lorentz spaces and the Navier-Stokes equations,"We derive basic properties of Triebel-Lizorkin-Lorentz spaces important in
the treatment of PDE. For instance, we prove Triebel-Lizorkin-Lorentz spaces to
be of class $\mathcal{HT}$, to have property $(\alpha)$, and to admit a
multiplier result of Mikhlin type. By utilizing these properties we prove the
Laplace and the Stokes operator to admit a bounded $H^\infty$-calculus. This is
finally applied to derive local strong well-posedness for the Navier-Stokes
equations on corresponding Triebel-Lizorkin-Lorentz ground spaces.",1710.01583v2
2018-10-24,Parameter estimation for a Lorentz invariance violation,"We employ techniques from quantum estimation theory (QET) to estimate the
Lorentz violation parameters in the 1+3-dimensional flat spacetime. We obtain
and discuss the expression of the quantum Fisher information (QFI) in terms of
the Lorentz violation parameter $\sigma_0$ and the momentum k of the created
particles. We show that the maximum QFI is achieved for a specific momentum
$k_{\mathrm{max}}$. We also find that the optimal precision of estimation of
the Lorentz violation parameter is obtained near the Planck scale.",1810.11379v1
2019-06-21,Test of Lorentz Violation with Astrophysical Neutrino Flavor in IceCube,"Astrophysical high-energy neutrinos observed by IceCube are sensitive to
small effects in a vacuum such as those motivated from quantum gravity
theories. Here, we discuss the potential sensitivity of Lorentz violation from
the diffuse astrophysical neutrino data in IceCube. The estimated sensitivity
reaches the Planck scale physics motivated region, providing IceCube with real
discovery potential of Lorentz violation.",1906.09240v1
2019-07-16,Ring Laser Gyroscope Tests of Lorentz Symmetry,"Interferometric gyroscope systems are being developed with the goal of
measuring general-relativistic effects including frame-dragging effects. Such
devices are also capable of performing searches for Lorentz violation. We
summarize efforts that relate gyroscope measurements to coefficients for
Lorentz violation in the gravity sector of the Standard-Model Extension.",1907.07071v1
2019-09-30,Searching for Lorentz violation in high-energy colliders,"Lorentz violation has been a popular field in recent years in the search for
new physics beyond the Standard Model. We present a general method to build all
Lorentz-violating terms in gauge field theories, including ones involving
operators of arbitrary mass dimension. Applying these results to two types of
experiments in high-energy colliders, light-by-light scattering and
deep-inelastic scattering, we extract first bounds on certain coefficients for
Lorentz violation.",1909.13782v1
2019-10-01,Lorentz and CPT Tests using Penning Traps,"The theoretical prospects for quantum electrodynamics with Lorentz-violating
operators of mass dimensions up to six are revisited in this work. The dominant
effects due to Lorentz and CPT violation are studied in measurements of
magnetic moments of particles confined in Penning traps. Using recently
reported experimental results, new coefficients for Lorentz violation are
constrained and existing bounds of various coefficients are improved.",1910.00456v1
2020-01-24,Explicit Lorentz violation in a static and spherically-symmetric spacetime,"Lorentz violation is motivated by quantum gravity and it is generically
described by nondynamical tensors. In this work a Lorentz violating extension
of general relativity is studied where a nondynamical tensor couples to the
Weyl tensor. A family of static and spherically symmetric solutions in vacuum
is found, confirming that there are consistent solutions with explicit Lorentz
violation in dynamical spacetimes. These solutions produce an unconventional
dependence of the gravitational redshift, which, in turn, leads to the first
bounds on such nondynamical tensor that do not rely on the physics of the early
universe. Moreover, the bounds obtained in this work are competitive with
respect to limits on similar nondynamical tensors.",2001.09217v1
2021-01-22,How to get from static to dynamic electromagnetism,"We demonstrate how to derive Maxwell's equations, including Faraday's law and
Maxwell's correction to Amp\`ere's law, by generalizing the description of
static electromagnetism to dynamical situations. Thereby, Faraday's law is
introduced as a consequence of the relativity principle rather than an
experimental fact, in contrast to the historical course and common textbook
presentations. As a by-product, this procedure yields explicit expressions for
the infinitesimal Lorentz and, upon integration, the finite Lorentz
transformation. The proposed approach helps to elucidate the relation between
Galilei and Lorentz transformations and provides an alternative derivation of
the Lorentz transformation without explicitly referring to the speed of light.",2101.10111v2
2017-05-09,Casimir effects in Lorentz-violating scalar field theory,"In this paper we consider a Lorentz-breaking extension of the theory for a
real massive scalar quantum field in the region between two large parallel
plates, with our manner to break the Lorentz symmetry is CPT-even, aether-like.
For this system we calculated the Casimir energy considering different boundary
conditions. It turns out to be that the Casimir energy strongly depends on the
direction of the constant vector implementing the Lorentz symmetry breaking, as
well as on the boundary conditions.",1705.03331v2
2017-05-22,One-loop correction to the photon velocity in Lorentz-violating QED,"We calculate a finite momentum-dependent part of the photon polarization
operator in a simple model of Lorentz-violating quantum electrodynamics
nonperturbatively at all orders of Lorentz-violating parameters. We sum
one-particle reducible diagrams into the modified photon propagator, and
determine the physical photon dispersion relation as the location of its pole.
The photon dispersion relation, as well as its group velocity, acquires the
one-loop momentum-dependent radiative correction. We constrain the
Lorentz-violating parameters for heavy charged fermions (muon, $\tau$-lepton,
top-quark) from the photon timing observations.",1705.07796v2
2018-07-20,Hypercomplex representation of the Lorentz's group,"Lorentz's group represented by the hypercomplex system of numbers, which is
based on dirac matrices, is investigated. This representation is similar to the
space rotation representation by quaternions. This representation has several
advantages. Firstly, this is reducible representation. That is why
transformation of different geometrical objects (vectors, antisymmetric tensors
of the second order and bispinors) are implemented by the same operators.
Secondly, the rule of composition of two arbitrary Lorentz's transformations
has a simple form. These advantages strongly simplify finding a lot of the laws
related to the Lorentz's group. In particular they simplify investigation of
the spin connection with Pauli-Lubanski pseudovector and Wigner little group.",1807.09104v2
2018-12-31,Gauge field theories with Lorentz-violating operators of arbitrary dimension,"The classification of Lorentz- and CPT-violating operators in nonabelian
gauge field theories is performed. We construct all gauge-invariant terms
describing propagation and interaction in the action for fermions and gauge
fields. Restrictions to the abelian, Lorentz-invariant, and isotropic limits
are presented. We provide two illustrative applications of the results to
quantum electrodynamics and quantum chromodynamics. First constraints on
nonlinear Lorentz-violating effects in electrodynamics are obtained using data
from experiments on photon-photon scattering, and corrections from nonminimal
Lorentz and CPT violation to the cross section for deep inelastic scattering
are derived.",1812.11672v2
2019-01-16,Estimating Dixmier traces of Hankel operators in Lorentz ideals,"In this paper we study Dixmier traces of powers of Hankel operators in
Lorentz ideals. We extend results of Engli\v{s}-Zhang to the case of powers
$p\geq 1$ and general Lorentz ideals starting from abstract extrapolation
results of Gayral-Sukochev. In the special case $p=2,4,6$ we give an exact
formula for the Dixmier trace. For general $p$, we give upper and lower bounds
on the Dixmier trace. We also construct, for any $p$ and any Lorentz ideal,
examples of non-measurable Hankel operators.",1901.05246v1
2019-02-06,NLO radiative correction to the Casimir energy in Lorentz-violating scalar field theory,"Violation of the Lorentz symmetry has important effects on physical
quantities including field propagators. Therefore, in addition to the leading
order, the sub-leading order of quantities may be modified. In this paper, we
calculate the next to leading (NLO) radiative corrections to the Casimir energy
in the presence of two perfectly conducting parallel plates for $\phi^4$ theory
with a Lorentz-breaking extension. We do the renormalization and investigate
these NLO corrections for three distinct directions of the Lorentz violation;
temporal direction, parallel and perpendicular to the plates.",1902.02015v1
2019-02-13,Embeddings of Orlicz-Lorentz spaces into $L_1$,"In this article, we show that Orlicz-Lorentz spaces $\ell^n_{M,a}$,
$n\in\mathbb N$ with Orlicz function $M$ and weight sequence $a$ are uniformly
isomorphic to subspaces of $L_1$ if the norm $\|\cdot\|_{M,a}$ satisfies
certain Hardy-type inequalities. This includes the embedding of some Lorentz
spaces $d^n(a,p)$. Our approach is based on combinatorial averaging techniques
and we prove a new result of independent interest that relates suitable
averages with Orlicz-Lorentz norms.",1902.05043v1
2019-03-27,Quantum aspects of antisymmetric tensor field with spontaneous Lorentz violation,"We study the quantization of a simple model of antisymmetric tensor field
with spontaneous Lorentz violation in curved spacetime. We evaluate the 1-loop
corrections at first order of metric perturbation, using a general covariant
effective action approach. We revisit the issue of quantum equivalence, and
find that it holds for non-Lorentz-violating modes but breaks down for Lorentz
violating modes.",1903.11364v2
2019-08-27,Lorentz-violating matter-gravity couplings in small-eccentricity binary pulsars,"Lorentz symmetry is an important concept in modern physics. Precision pulsar
timing was used to put tight constraints on the coefficients for Lorentz
violation in the pure-gravity sector of the Standard-Model Extension (SME). We
extend the analysis to Lorentz-violating matter-gravity couplings, utilizing
three small-eccentricity relativistic neutron star (NS) -- white dwarf (WD)
binaries. We obtain compelling limits on various SME coefficients related to
the neutron, the proton, and the electron. These results are complementary to
limits obtained from lunar laser ranging and clock experiments.",1908.10019v1
2019-08-30,Prospects for Lorentz-Violation Searches at the LHC and Future Colliders,"Hadron colliders are providing a unique opportunity for testing Lorentz
invariance and CPT symmetry at high energy and in a laboratory. A first
measurement in the top-quark sector was performed at the Tevatron. We present
here prospective studies for testing Lorentz invariance in top-quark pair
production at the LHC and future colliders. The b-quark sector was investigated
recently at LHCb. Eventually, new bounds on photon parameters can be extracted
from the observation of TeV photons at the LHC. We will conclude by
highlighting other opportunities provided by hadron colliders.",1908.11734v1
2019-11-18,Lorentz-Violating Running of Coupling Constants,"We compute the full vacuum polarization tensor in the minimal QED extension.
We find that its low-energy limit is dominated by the radiatively induced
Chern-Simons-like term and the high-energy limit is dominated by the c-type
coefficients. We investigate the implications of the high-energy limit for the
QED and QCD running couplings. In particular, the QCD running offers the
possibility to study Lorentz-violating effects on the parton distribution
functions and observables such as the hadronic R ratio.",1911.07780v1
2019-11-18,Lorentz Violation and Partons,"A parton-model description of high-energy hadronic interactions in the
presence of Lorentz violation is presented. This approach is used to study
lepton-hadron and hadron-hadron interactions at large momentum transfer. Cross
sections for deep inelastic scattering and the Drell-Yan process are calculated
at first order for minimal and nonminimal Lorentz violation. Estimated bounds
are placed using existing LHC and future US-based Electron-Ion Collider data.",1911.07791v1
2019-12-20,Mining the Data Tables for Lorentz and CPT Violation,"In this conference proceedings, some comments on the present status and
recent growth of efforts to find Lorentz and CPT violation are given by
extracting metrics from the annually updated ""Data Tables for Lorentz and CPT
Violation."" They reveal that tests span all the sectors of particle and
gravitational physics, and have shown remarkable and consistent growth. Through
numerous innovations and refinements in experiments, a large body of data has
been amassed with ever-increasing precisions. The Tables are available through
the Cornell preprint archive at arXiv:0801.0287.",1912.09620v1
2020-08-12,Ehrenfest Wind-Tree Model is Dynamically Richer Than the Lorentz Gas,"We consider a physical Ehrenfests' Wind-Tree model where a moving particle is
a hard ball rather than (mathematical) point particle. We demonstrate that a
physical periodic Wind-Tree model is dynamically richer than a physical or
mathematical periodic Lorentz gas. Namely, the physical Wind-Tree model may
have diffusive behavior as the Lorentz gas does, but it has more superdiffusive
regimes than the Lorentz gas. The new superdiffusive regime where the diffusion
coefficient D(t)~(ln t)^2 of dynamics seems to be never observed before in any
model.",2008.05385v1
2020-09-04,Effects of Lorentz violation in superconductivity,"This paper presents the effects of Lorentz violation in superconductivity.
Constructing a Lorentz-Violating Ginzburg-Landau theory of superconductivity we
discuss the influence of the Lorentz-Violating tensors $\hat{k}_{c}^{ij}$ and
$\hat{k}_a^i$ in the London's depth penetration, in the coherence length and
critical magnetic field.",2009.02301v2
2021-08-25,Lorentz Ricci solitons of 4-dimensional non-Abelian nilpotent Lie groups,"The goal of this paper is to investigate which one of thenon-isometric left
invariant Lorentz metrics on 4-dimensional nilpotent Lie groups $H_3 \times
{\Bbb R}$ and $G_4$ satisfy in Ricci Soliton equation. Among the left-invariant
Lorentzian metrics on $H_3 \times {\Bbb R}$, ~ $g_{\lambda}^{+}$ is a shrinking
while $g_{\lambda}^{+}$ and $g_{\mu}$ are expanding and also $g_0^1, g_0^2,
g_0^3$ have Ricci solitons. We exhibit among the non-isometric left invariant
Lorentz metric on the group $G_4$ only $g_1^\lambda, g_2^\lambda$ have Lorentz
Ricci solitons and $g_2^\lambda$ is a shrinking.",2108.11380v1
2021-09-15,Interpolation inequalities in function spaces of Sobolev-Lorentz type,"Interpolation inequalities in Triebel-Lizorkin-Lorentz spaces and
Besov-Lorentz spaces are studied for both inhomogeneous and homogeneous cases.
First we establish interpolation inequalities under quite general assumptions
on the parameters of the function spaces. Several results on necessary
conditions are also provided. Next, utilizing the interpolation inequalities
together with some embedding results, we prove Gagliardo-Nirenberg inequalities
for fractional derivatives in Lorentz spaces, which do hold even for the
limiting case when one of the parameters is equal to 1 or $\infty$.",2109.07518v1
2022-01-25,Possible Lorentz symmetry violation from broken Weyl invariance,"In this work, we investigate a theory of linear Weyl gravity coupled to a
scalar field and study the scenario in which Lorentz symmetry is broken by a
non-vanishing vacuum expectation value of the Weyl field in the flat space
limit after Weyl symmetry breaking. We show that a $CPT$-odd Lorentz-violating
interaction is generated after symmetry breaking. Features of different
symmetry-broken phases and their dependence on the spacetime character of the
generated Lorentz-violating background are discussed. Also, we analyze the
naturalness of the theory by showing that the light mass scale is protected
from large radiative corrections due to an enhanced spacetime symmetry.",2201.10086v2
2022-07-31,Searches for Lorentz and CPT Violation with Confined Particles,"An overview of recent progress on searches for Lorentz- and CPT-violating
signals with confined particles and antiparticles in Penning traps is
presented. In the context of the Standard-Model Extension (SME), leading-order
shifts in the cyclotron and anomaly frequencies of a confined particle and
antiparticle due to Lorentz and CPT violation are provided. The two frequencies
are then related to comparisons of charge-to-mass ratios and magnetic moments
between particles and antiparticles. Applying reported results from
Penning-trap experiments leads to new limits on various coefficients for
Lorentz violation.",2208.00517v1
2022-08-18,Using ultra-high energy cosmic rays and air showers to test Lorentz invariance within modified Maxwell theory,"Cosmic rays and air showers at ultra-high energy are unique tools to test the
validity of Lorentz invariance. A brief overview is given on such tests
focusing on isotropic, non-birefringent Lorentz violation (LV) in the photon
sector. Based on the apparent absence of vacuum Cherenkov radiation and photon
decay, the LV parameter $\kappa$ is bound to $-0.6 \cdot 10^{-20} < \kappa < 6
\cdot 10^{-20}$ (98\% CL). We report an updated limit from cosmic-ray photon
observations and preliminary results on testing vacuum Cherenkov radiation in
air showers.",2208.08747v1
2022-08-26,Lorentz violation in electromagnetic moments of fermions,"Lorentz-violating Yukawa couplings lying within the renormalizable part of
the SME generate Lorentz-invariant one-loop contributions to electromagnetic
moments of fermions. These proceedings provide a discussion on such
contributions and present bounds on SME coefficients from experimental data on
electromagnetic moments. Constraints as restrictive as $\sim10^{-14}$ are
found.",2208.12399v2
2022-11-03,Lorentz Dissociation of Hydrogen Ions in a Cyclotron,"Stripping extraction of hydrogen molecular ions has gained interest in the
cyclotron industry due to its high extraction efficiency. However, the magnetic
field could result in undesired Lorentz dissociation of the hydrogen
anion/molecular ions during acceleration. Studies of dissociation under
electric fields comparable to that of a Lorentz-transformed magnetic field in a
typical cyclotron (a few MV/cm) are sparse. Hence, in order to fill in the
missing yet crucial information when designing a cyclotron, this work compiles
and summarizes the study of Lorentz dissociation of H$^-$, H$_2^+$ and H$_3^+$
for stripping extraction in a cyclotron.",2211.01614v1
2023-04-06,Perturbative Aspects of CPT-Even Lorentz-Violating Scalar Chromodynamics,"In this work, we formulate the theory of Lorentz-violating scalar Quantum
Chromodynamics with an arbitrary non-Abelian gauge group. This theory belongs
to the class of models encompassed by the standard model extension framework.
At the lowest order in the theory's Lorentz violation parameters, we calculate
the divergent quantum corrections, including the renormalization group
$\beta$-functions of the theory. The Lorentz-violating sector is shown to be
scale invariant if there is a particular relation between the couplings.",2304.03025v2
2023-09-28,Anomalous function of a Lorentz-violating QED effective action and the relation between compact bulk scalar propagator and path integral duality,"In this paper, we consider a compact five dimensional spacetime with the
structure $\mathcal{M}^{1,3}\times S^{1}$. Generally speaking, motion on such a
structure will break Lorentz invariance, allowing for causal bulk signals to
propagate superluminally. Based on recent articles, we calculate the anomalous
function of a gauge invariant but Lorentz-violating term in the $4D$ QED
effective action by using path integral. Finally, we find that the compact bulk
scalar propagator and path integral duality are consistent, this result brings
a new perspective: the behavior of breaking Lorentz invariance caused by
dimensional compactness can be seen as path integral duality.",2309.16226v1
2024-02-27,Relation between the minimal Lorentz surfaces in $\mathbb R^4_2$ and $\mathbb R^3_1$,"In this paper we give Weierstrass-type representation formulas for the null
curves and for the minimal Lorentz surfaces in the Minkowski 3-space $\mathbb
R^3_1$ using real-valued functions. Applying the Weierstrass-type
representations for the null curves, we find a correspondence between the null
curves in $\mathbb R^4_2$ and the pairs of null curves in $\mathbb R^3_1$.
Based on this correspondence, we obtain a relation between the minimal Lorentz
surfaces in $\mathbb R^4_2$ and the pairs of minimal Lorentz surfaces in
$\mathbb R^3_1$.",2402.17850v1
2012-06-27,ABC Resonance Structure in the Double-Pionic Fusion to 4He,"Exclusive and kinematically complete high-statistics measurements of the
double pionic fusion reaction $dd \to ^4$He$\pi^0\pi^0$ have been performed in
the energy range 0.8 - 1.4 GeV covering thus the region of the ABC effect,
which denotes a pronounced low-mass enhancement in the $\pi\pi$-invariant mass
spectrum. The experiments were carried out with the WASA detector setup at
COSY. Similar to the observation in the basic $pn \to d \pi^0\pi^0$ reaction,
the data reveal a correlation between the ABC effect and a resonance-like
energy dependence in the total cross section. The maximum occurs at m=2.37 GeV
+ 2$m_N$, i.e. at the same position as in the basic reaction. The observed
resonance width $\Gamma \approx$ 160 MeV can be understood from broadening due
to Fermi motion of the nucleons in initial and final nuclei together with
collision damping. Differential cross sections are described equally well by
the hypothesis of a $pn$ resonance formation during the reaction process.",1206.6337v1
2019-10-23,Multiwavelength observations of GRB 140629A. A long burst with an achromatic jet break in the optical and X-ray afterglow,"We investigate the long GRB140629A through multiwavelength observations,
which cover optical, infrared and X-rays between 40s and 3yr after the burst,
to derive the properties of the dominant jet and its host galaxy. Polarisation
observations by the MASTER telescope indicate that this burst is weakly
polarised. The optical spectrum contains absorption features, from which we
confirm the redshift of the GRB as originating at z=2.276. We performed
spectral fitting of the X-rays to optical afterglow data and find there is no
strong spectral evolution. We determine the hydrogen column density to be
7.2x10^21cm^-2 along the line of sight. The afterglow in this burst can be
explained by a blast wave jet with a long-lasting central engine expanding into
a uniform medium in the slow cooling regime. At the end of energy injection, a
normal decay phase is observed in both the optical and X-ray bands. An
achromatic jet break is also found in the afterglow light curves 0.4d after
trigger. We fit the multiwavelength data simultaneously with a model based on a
numerical simulation and find that the observations can be explained by a
narrow uniform jet in a dense environment with an opening angle of 6.7deg
viewed 3.8deg off-axis, which released a total energy of 1.4x10^54erg. Using
the redshift and opening angle, we find GRB 140629A follows both the Ghirlanda
and Amati relations. From the peak time of the light curve, identified as the
onset of the forward shock (181s after trigger), the initial Lorentz factor is
constrained in the range 82-118. Fitting the host galaxy photometry, we find
the host to be a low mass, star-forming galaxy with a star formation rate of
logSFR=1.1^+0.9_-0.4Myr^-1. We obtain a value of the neutral hydrogen density
by fitting the optical spectrum, logN(HI)=21.0+-0.3, classifying this host as a
damped Lyman-alpha. High ionisation lines are also detected in the spectrum.",1910.10747v1
1994-12-30,Violation of the Energy Conservation Law in Lorentz-Dirac Equations for More Than One Charge,"An exact solution of Lorentz-Dirac equations where the energy conservation
law is violated, is described herein for the case of two charges.",9412391v1
2001-03-01,Spontaneous Violation of Lorentz and CPT Symmetry,"Overview of spontaneous Lorentz and CPT breaking mechanism in the context of
the standard model contributed to the proceedings for the Coral Gables meeting.",0103021v1
2001-04-23,Topics in Lorentz and CPT Violation,"This talk outlines some recent theoretical developments in Lorentz and CPT
violation.",0104227v1
2001-11-05,CPT and Lorentz Violation in Kaons and Other Systems,"This talk provides a status report on CPT violation in neutral-meson
oscillations, focusing on implications of the CPT- and Lorentz-violating
standard-model extension.",0111041v1
2002-02-10,CPT and Lorentz Violation in Neutral-Meson Oscillations,"In this talk, the status of CPT tests with neutral mesons is reviewed in the
context of quantum field theory and the Lorentz- and CPT-violating
standard-model extension.",0202094v1
2003-12-26,Superfield Realizations of Lorentz Violation,"Lorentz-violating extensions of the Wess-Zumino model have been formulated in
superspace. The models respect a supersymmetry algebra and can be understood as
arising from suitably modified superspace transformations.",0312356v1
1999-04-20,Lorentz Covariance in Epstein-Glaser Renormalization,"We give explicit and inductive formulas for the construction of a Lorentz
covariant renormalization in the EG approach. This automatically provides for a
covariant BPHZ subtraction at totally spacelike momentum useful for massless
theories.",9904136v2
1999-07-27,String theory in Lorentz-invariant time-like gauge,"A theory of closed bosonic string in time-like gauge, related in
Lorentz-invariant way with the world sheet, is considered. Absence of quantum
anomalies in this theory is shown.",9907196v1
2001-12-27,Supersymmetry and Lorentz Violation,"Supersymmetric field theories can be constructed that violate Lorentz and CPT
symmetry. We illustrate this with some simple examples related to the original
Wess-Zumino model.",0112243v1
2005-01-04,Lorentz invariance of scalar field action on $κ$-Minkowski space-time,"We construct field theory on noncommutative $\kappa$-Minkowski space-time.
Having the Lorentz action on the noncommutative space-time coordinates we show
that the field lagrangian is invariant. We show that noncommutativity requires
replacing the Leibnitz rule with the coproduct one.",0501017v1
2006-03-01,Concerning Bjorken's Model of Spontaneous Breakdown of Lorentz Invariance,"We revisit Bjorken's model of spontaneous breakdown of Lorentz invariance. We
show that the model possesses zero mass, spin zero (scalar) Nambu-Goldstone
boson, in addition to the zero mass, spin one (vector) photon.",0603009v1
1996-10-01,An interpolation theorem related to the a.e. convergence of integral operators,"We show that for integral operators of general form the norm bounds in
Lorentz spaces imply certain norm bounds for the maximal function. As a
consequence, the a.e. convergence for the integral operators on the Lorentz
spaces follows from the appropriate norm estimates.",9610217v1
1998-10-29,Sur les espaces-temps homogenes,"Here, we classify Lie groups acting isometrically on compact Lorentz
manifolds, and in particular we describe the geometric structure of compact
homogeneous Lorentz manifolds.",9810202v1
1999-01-06,On the Quantum Lorentz Group,"The quantum analogues of Pauli matrices are introduced and investigated. From
these matrices and an appropriate trace over spinorial indiceswe construct a
quantum Minkowsky metric. In this framework, we show explicitely the
correspondance between the SL(2,C) and Lorentz quantum groups.",9901020v1
2006-09-29,On the Conformal Geometry of Transverse Riemann-Lorentz Manifolds,"Physical reasons suggested in \cite{Ha-Ha} for the \emph{Quantum Gravity
Problem} lead us to study \emph{type-changing metrics} on a manifold. The most
interesting cases are \emph{Transverse Riemann-Lorentz Manifolds}. Here we
study the conformal geometry of such manifolds.",0609838v1
1997-08-15,High-Energy Nuclear Physics with Lorentz Symmetry Violation,"If textbook Lorentz invariance is actually a property of the equations
describing a sector of the excitations of vacuum above some critical distance
scale, several sectors of matter with different critical speeds in vacuum can
coexist and an absolute rest frame (the vacuum rest frame) may exist without
contradicting the apparent Lorentz invariance felt by ""ordinary"" particles
(particles with critical speed in vacuum equal to $c$, the speed of light).
Sectorial Lorentz invariance, reflected by the fact that all particles of a
given dynamical sector have the same critical speed in vacuum, will then be an
expression of a fundamental sectorial symmetry (e.g. preonic grand unification
or extended supersymmetry) protecting a parameter of the equations of motion.
Furthermore, the sectorial Lorentz symmetry may be only a low-energy limit, in
the same way as the relation $\omega $ (frequency) = $c_s$ (speed of sound) $k$
(wave vector) holds for low-energy phonons in a crystal. In this context,
phenomena such as the absence of Greisen-Zatsepin-Kuzmin cutoff for protons and
nuclei and the stability of unstable particles (e.g. neutron, several
nuclei...) at very high energy are basic properties of a wide class of
noncausal models where local Lorentz invariance is broken introducing a
fundamental length. Observable phenomena are expected at very short wavelength
scales, even if Lorentz symmetry violation remains invisible to standard
low-energy tests. We present a detailed discussion of the implications of
Lorentz symmetry violation for very high-energy nuclear physics.",9708028v2
1997-03-12,Lorentz Invariance and Superluminal Particles,"If textbook Lorentz invariance is actually a property of the equations
describing a sector of matter above some critical distance scale, several
sectors of matter with different critical speeds in vacuum can coexist and an
absolute rest frame (the vacuum rest frame, possibly related to the local rest
frame of the expanding Universe) may exist without contradicting the apparent
Lorentz invariance felt by ""ordinary"" particles (particles with critical speed
in vacuum equal to $c$ , the speed of light). Sectorial Lorentz invariance,
reflected by the fact that all particles of a given dynamical sector have the
same critical speed in vacuum, will then be an expression of a fundamental
sectorial symmetry (e.g. preonic grand unification or extended supersymmetry)
protecting a parameter of the equations of motion. We study the breaking of
Lorentz invariance in such a scenario, with emphasis on mixing between the
""ordinary"" sector and a superluminal sector, and discuss with examples the
consequences of existing data. The sectorial universality of the value of the
high-energy speed in vacuum, even exact, does not necessarily imply that
Lorentz invariance is not violated and does not by itself exclude the
possibility to produce superluminal particles at accelerators or to find them
in experiments devoted to high-energy cosmic rays. Similarly, the stringent
experimental bounds on Lorentz symmetry violation at low energy cannot be
extrapolated to high-energy phenomena. Several basic questions related to
possible effects of Lorentz symmetry violation are discussed, and potential
signatures are examined.",9703020v1
1997-08-25,Lorentz Symmetry Violation and Superluminal Particles at Future Colliders,"If textbook Lorentz invariance is actually a property of the equations
describing a sector of the excitations of vacuum above some critical distance
scale, several sectors of matter with different critical speeds in vacuum can
coexist and an absolute rest frame (the vacuum rest frame) may exist without
contradicting the apparent Lorentz invariance felt by ""ordinary"" particles
(particles with critical speed in vacuum equal to $c$, the speed of light).
Sectorial Lorentz invariance, reflected by the fact that all particles of a
given dynamical sector have the same critical speed in vacuum, will then be an
expression of a fundamental sectorial symmetry (e.g. preonic grand unification
or extended supersymmetry) protecting a parameter of the equations of motion.
Furthermore, the sectorial Lorentz symmetry may be only a low-energy limit, in
the same way as the relation $\omega $ (frequency) = $c_s$ (speed of sound) $k$
(wave vector) holds for low-energy phonons in a crystal. In this context,
phenomena such as the absence of Greisen-Zatsepin-Kuzmin cutoff and the
stability of unstable particles at very high energy are basic properties of a
wide class of noncausal models where local Lorentz invariance is broken
introducing a fundamental length. Observable phenomena from Lorentz symmetry
violation and superluminal sectors of matter are expected at very short
wavelength scales, even if Lorentz symmetry violation remains invisible to
standard low-energy tests. We discuss signatures of this new physics at LHC and
at other possible future colliders.",9708028v2
1997-11-25,Failure of Lorentz-Dirac Approach to Radiation Reaction for Extremely Large Velocities ?,"On the model of moving rigid charged body is shown that the Lorentz-Dirac
approach to radiation reaction in classical electrodynamics does not work for
trajectories of body close to the light cone.",9711024v1
1999-11-25,Full Physical Derivation and Meaning of Lorentz Transformation,"In the line of thought of Einstein's 1905 paper on relativity, I get a
physical derivation of Lorentz transformation (LT) answering its main criticism
and considerably enlarging the area of applications of the theory of
relativity.",9911067v1
2002-06-10,Can we derive the Lorentz force from Maxwell's equations?,"The Lorentz force can be obtained from Maxwell's equations in the Coulomb
gauge provided that we assume that the electric portion of the force acted on a
charge is known, and the magnetic component is perpendicular to the velocity of
motion of the charged particle.",0206022v1
2003-05-29,Lorentz Invariance of Neutrino Oscillations,"It is shown that, in spite of the appearances, the standard expression for
the oscillation probability of ultrarelativistic neutrinos is Lorentz
invariant.",0305122v1
2005-03-18,Lorentz-contraction formula from non-simultaneous events,"We present a derivation of the relativistic length-contraction formula based
on Lorentz space-time transformations on non-simultaneous events. Our
derivation avoids the disputable story about the stationary observer and its
simultaneous measurements of object's end-points.",0503156v2
2005-06-20,Derivation of transformation equations for the parameters that characterize a plane acoustic wave without using phase invariance and Lorentz-Einstein transformation,"We show that the transformation equations for the parameters that
characterize a plane acoustic wave: period, (frequency), wave vector, wave
length and phase velocity can be derived without using phase invariance and
Lorentz-Einstein transformation",0506156v1
2007-01-23,Lorentz covariance of the canonical perfect lens,"The canonical perfect lens--comprising three slabs, each made of a linear,
homogeneous, bianisotropic material with orthorhombic symmetry--is Lorentz
covariant.",0701256v1
2002-01-25,Lorentz-Invariant Time-Energy Uncertainty Relation for Relativistic Photon,"The time-energy uncertainty relation is discussed for a relativistic massless
particle. The Lorentz-invariant uncertainty relation is obtained between the
root-mean-square energy deviation and the scatter of registration time. The
interconnection between this uncertainty relation and its classical analogue is
established.",0201113v1
2007-04-23,"Spontaneous Lorentz Violation, Gravity, and Nambu-Goldstone Modes","A brief summary is presented of recent work examining the fate of the
Nambu-Goldstone modes in gravitational theories with spontaneous Lorentz
violation.",0704.2994v2
2007-09-14,Lorentz transformation directly from the invariance of the speed of light via the addition law of parallel speeds,"We show that starting with the addition law of parallel speeds derived as a
consequence of the invariance of the speed of light, the Lorentz
transformations for the space-time coordinates can be derived.",0709.2266v1
2007-10-04,Analysis of cosmic microwave background radiation in the presence of Lorentz violation,"We examine the effects Lorentz violation on observations of cosmic microwave
background radiation. In particular, we focus on changes in polarization caused
by vacuum birefringence. We place stringent constraints on previously untested
violations.",0710.1110v1
2009-01-26,Lorentz and SU(3) groups derived from cubic quark algebra,"We show that the Lorentz and the SU(3) groups can be derived from the
covariance principle conserving a $Z_3$-graded three-form on a $Z_3$-graded
cubic algebra representing quarks endowed with non-standard commutation laws.",0901.3961v1
2009-03-12,Limiting fractional and Lorentz spaces estimates of differential forms,"We obtain estimates in Besov, Lizorkin-Triebel and Lorentz spaces of
differential forms on R^n in terms of their L^1 norm.",0903.2182v1
2009-04-28,Area minimization among marginally trapped surfaces in Lorentz-Minkowski space,"We study an area minimization problem for spacelike zero mean curvature
surfaces in four dimensional Lorentz-Minkowski space. The areas of these
surfaces are compared of with the areas of certain marginally trapped surfaces
having the same boundary values.",0904.4332v1
2010-03-25,Lorentz contraction according to the wave nature of the light,"The wave nature of the light, applied to the kinematics of the moving bodies,
permits to investigate and find a coherent solution on some questions raised by
the theory of special relativity about the Lorentz contraction.",1003.4833v1
2011-01-05,"Reply to ""Comment on 'Noncommutative gauge theories and Lorentz symmetry'""","This is a reply to ""Comment on 'Noncommutative gauge theories and Lorentz
symmetry,'"" Phys. Rev. D 77 (2008) 048701 by Alfredo Iorio.",1101.0877v1
2011-08-30,Norm closed operator ideals in Lorentz sequence spaces,"In this paper, we study the structure of closed algebraic ideals in the
algebra of operators acting on a Lorentz sequence space.",1108.6026v1
2011-12-29,Neutrinos with Lorentz-violating operators of arbitrary dimension,"The behavior of fermions in the presence of Lorentz and CPT violation is
studied. Allowing for operators of any mass dimension, we classify all
Lorentz-violating terms in the quadratic Lagrange density for free fermions.
The result is adapted to obtain the effective hamiltonian describing the
propagation and mixing of three flavors of left-handed neutrinos in the
presence of Lorentz violation involving operators of arbitrary mass dimension.
A characterization of the neutrino coefficients for Lorentz violation is
provided via a decomposition using spin-weighted spherical harmonics. The
restriction of the general theory to various special cases is discussed,
including among others the renormalizable limit, the massless scenario,
flavor-blind and oscillation-free models, the diagonalizable case, and several
isotropic limits. The formalism is combined with existing data on neutrino
oscillations and kinematics to extract a variety of measures of coefficients
for Lorentz and CPT violation. For oscillations, we use results from the
short-baseline experiments LSND and MiniBooNE to obtain explicit sensitivities
to effects from flavor-mixing Lorentz-violating operators up to mass dimension
10, and we present methods to analyze data from long-baseline experiments. For
propagation, we use time-of-flight measurements from the supernova SN1987A and
from a variety of experiments including MINOS and OPERA to constrain
oscillation-free Lorentz-violating operators up to mass dimension 10, and we
discuss constraints from threshold effects in meson decays and Cherenkov
emission.",1112.6395v2
2012-08-01,Lorentz-Dirac equation in the delta-function pulse,"We formulate the Lorentz-Dirac equation in the plane wave and in the Dirac
delta-function pulse. The discussion on the relation of the Dirac
delta-function to the ultrashort laser pulse is involved.",1208.0488v1
2012-10-17,Individual lower bound for Calderon's generalized Lorentz norm estimates,"We find the exact values for constants in bilateral Calderon-Stein-Weiss
inequalities between tail (Marcinkiewicz) norm and weak Lebesgue (Lorentz)
norm.
  Possible applications: Functional Analysis (for instance, interpolation of
operators), Integral Equations, Probability Theory and Statistics (tail
estimations for random variables).",1210.4832v1
2012-11-27,"Hardy's operator and normability of generalized Lorentz-Marcinkiewicz spaces, with sharp or weakly sharp constant estimation","We introduce a Banach rearrangement invariant (tail) quasy-norm by means of
Hardy's (Cesaro) average on the (measurable) functions defined on some
measurable space which is a slight generalization of classical
Lorentz-Marcinkiewicz norm and find for it an equivalent norm expression.",1211.6415v1
2012-12-10,"Lorentz Symmetry, the SME, and Gravitational Experiments","This proceedings contribution summarizes the implications of recent SME-based
investigations of Lorentz violation for gravitational experiments.",1212.2195v1
2013-02-05,Observational Constraints on Local Lorentz Invariance,"The idea that local Lorentz invariance might be violated due to new physics
that goes beyond the Standard Model of particle physics and Einstein's General
Relativity has received a great deal of interest in recent years. At the same
time, new experiments have been designed and conducted that are able to test
Lorentz symmetry at unprecedented levels. Much of this theoretical and
experimental progress has been driven by the development of the framework for
investigating Lorentz violation known as the Standard Model Extension (SME).
The SME is the lagrangian-based effective field theory that by definition
contains all Lorentz-violating interaction terms that can be written as
observer scalars involving particle fields in the Standard Model and
gravitational fields in a generalized theory of gravity. This includes all
terms that could arise from a process of spontaneous Lorentz violation as well
as terms that explicitly break Lorentz symmetry. In this article, an overview
of the SME is presented, including its motivations and construction. A very
useful minimal version of the SME in Minkowski spacetime that maintains gauge
invariance and power-counting renormalizability is constructed as well. Data
tables summarizing tests of local Lorentz invariance for the different particle
sectors in the Standard Model and with gravity are maintained by Kosteleck\'y's
group at Indiana University. A partial survey of these tests, including some of
the high-precision sensitivities they attain, is presented here.",1302.1150v1
2013-06-02,Gauge invariant electromagnetic properties of fermions induced by CPT violation in the Standard Model Extension,"Low-energy Lorentz-invariant quantities could receive contributions from a
fundamental theory producing small Lorentz-violating effects. Within the
Lorentz-violating extension of quantum electrodynamics, we investigate,
perturbatively, the contributions to the one-loop $ff\gamma$ vertex from the
$CPT$-violating axial coupling of a vector background field to fermions. We
find that the resulting vertex function has a larger set of Lorentz structures
than the one characterizing the usual, Lorentz invariant, parametrization of
the $ff\gamma$ vertex. We prove gauge invariance of the resulting one-loop
expression through a set of gauge invariant nonrenormalizable operators
introducing new-physics effects at the first and second orders in Lorentz
violation, and which generate tree-level contributions to the $ff\gamma$
vertex. Whereas loop contributions involving parameters that violate Lorentz
invariance at the first order are $CPT$-odd, those arising at the second order
are $CPT$-even, so that contributions to low-energy physics are restricted to
emerge for the first time at the second order. In this context, we derive a
contribution to anomalous magnetic moment of fermions, which we use to set a
bound on Lorentz violation.",1306.0262v2
2013-11-05,Lorentz estimates for obstacle parabolic problems,"We prove that the spatial gradient of (variational) solutions to parabolic
obstacle problems of p-Laplacian type enjoys the same regularity of the data
and of the derivatives of the obstacle in the scale of Lorentz spaces.",1311.1230v1
2013-11-28,Lower bound for the escape probability in the Lorentz Mirror Model on the lattice,"We show that in the Lorentz mirror model, at any density of mirrors, the
probability of a particle starting at the origin to reach distance n is at
least 1/(2n+1).",1311.7437v1
2014-01-24,Quasihomogeneous three-dimensional real analytic Lorentz metrics,"We classify germs at the origin of real analytic Lorentz metrics on R^3 which
are quasihomogeneous, in the sense that they are locally homogeneous on an open
set containing the origin in its closure, but not locally homogeneous in the
neighborhood of the origin.",1401.6272v1
2014-02-26,Two-dimensional Lorentz invariance of spherically symmetric black holes,"We show that a static spherically symmetric black hole, in a generic theory
of gravity with generic matter fields, has a two-dimensional Lorentz symmetry.",1402.6707v1
2015-05-16,Constraints on the Bulk Lorentz Factors of GRB X-Ray Flares,"X-ray flares were discovered in the afterglow phase of gamma-ray bursts
(GRBs) by the {\em Swift} satellite a decade ago and known as a canonical
component in GRB X-ray afterglows. In this paper, we constrain the Lorentz
factors of GRB X-ray flares using two different methods. For the first method,
we estimate the lower limit on the bulk Lorentz factor with the flare duration
and jet break time. In the second method, the upper limit on the Lorentz factor
is derived by assuming that the X-ray flare jet has undergone saturated
acceleration. We also re-estimate the initial Lorentz factor with GRB afterglow
onsets, and find the coefficient of the theoretical Lorentz factor is 1.67
rather than the commonly used 2 for interstellar medium (ISM) and 1.44 for the
wind case. We find that the correlation between the limited Lorentz factor and
the isotropic radiation energy of X-ray flares in the ISM case is more
consistent with that of prompt emission than the wind case in a statistical
sense. For a comparison, the lower limit on Lorentz factor is statistically
larger than the extrapolation from prompt bursts in the wind case. Our results
indicate that X-ray flares and prompt bursts are produced by the same physical
mechanism.",1505.04233v1
2015-06-29,Semi-simple Lie groups acting conformally on compact Lorentz manifolds,"We give a classification, up to local isomorphisms, of semi-simple Lie groups
without compact factors that can act faithfully and conformally on a compact
Lorentz manifold of dimension greater than or equal to $3$.",1506.08693v1
2015-07-22,Strongly enhanced effects of Lorentz symmetry violation in entangled Yb+ ions,"Lorentz symmetry is one of the cornerstones of modern physics. However, a
number of theories aiming at unifying gravity with the other fundamental
interactions including string field theory suggest violation of Lorentz
symmetry [1-4].
  While the energy scale of such strongly Lorentz symmetry-violating physics is
much higher than that currently attainable by particle accelerators, Lorentz
violation may nevertheless be detectable via precision measurements at low
energies [2]. Here, we carry out a systematic theoretical investigation of the
sensitivity of a wide range of atomic systems to violation of local Lorentz
invariance (LLI). Aim of these studies is to identify which atom shows the
biggest promise to detect violation of Lorentz symmetry. We identify the Yb+
ion as an ideal system with high sensitivity as well as excellent experimental
controllability. By applying quantum information inspired technology to Yb+, we
expect tests of LLI violating physics in the electron-photon sector to reach
levels of $10^{-23}$, five orders of magnitude more sensitive than the current
best bounds [5-7]. Most importantly, the projected sensitivity of $10^{-23}$
for the Yb+ ion tests will allow for the first time to probe whether Lorentz
violation is minimally suppressed at low energies for photons and electrons.",1507.06048v1
2015-10-30,On blowup of nonendpoint borderline Lorentz norms for the Navier-Stokes equations,"Assuming $T$ is a potential blow up time for the Navier-Stokes system in
$\mathbb{R}^3$ or $\mathbb{R}^3_+$, we show that the $L^{3,q}$ Lorentz norm,
with $q$ finite, of the velocity field goes to infinity as time $t$ approaches
$T$.",1510.09178v1
2016-02-17,Lorentz Invariant Vacuum Solutions in General Relativity,"All Lorentz invariant solutions of vacuum Einstein's equations are found. It
is proved that these solutions describe space-times of constant curvature.",1602.06331v1
2017-03-20,Triply periodic zero mean curvature surfaces in Lorentz-Minkowski 3-space,"We construct triply periodic zero mean curvature surfaces of mixed type in
the Lorentz-Minkowski 3-space, with the same topology as the triply periodic
minimal surfaces in the Euclidean 3-space, called Schwarz rPD surfaces.",1703.06600v1
2018-04-13,Flat compact Hermite-Lorentz manifolds in dimension 4,"We give a classification, up to finite cover, of flat compact complete
Hermite-Lorentz manifolds up to complex dimension 4.",1804.04809v2
2017-04-01,Bounded composition operator on Lorentz spaces,"We study a composition operator on Lorentz spaces. In particular we provide
necessary and sufficient conditions under which a measurable mapping induces a
bounded composition operator.",1704.00127v1
2009-12-03,On the proper choice of a Lorentz-covariant relativistic Lagrangian,"A proper choice for the sign of the Lorentz-covariant relativistic Lagrangian
for a particle moving in an electromagnetic field is presented. This choice is
based on which space-time metric is used in the representation of the
relativistic particle dynamics.",0912.0655v1
2012-03-31,Lorentz Invariant Phenomenological Model of Quantum Gravity: A Minimalistic Presentation,"The purpose of this paper is to give a minimalistic and self-contained
presentation of a Lorentz Invariant phenomenological model of Quantum Gravity.",1204.0055v1
2012-05-16,Constraining the Bulk Lorentz Factor of GRB Outflow in the Magnetic-dominated Jet Model,"Recent observations by the Fermi-LAT showed that there are delayed arrivals
of GeV photons relative to the onset of MeV photons in some GRBs. In order to
avoid a large optical depth, the minimal value of the Lorentz factor has been
estimated to be higher than 1000 in some brightest bursts. In this paper, we
present a detailed calculation of the time delay between the MeV and GeV
photons in the framework of the magnetic-dominated jet model. We find that the
time delay strongly depends on the saturated bulk Lorentz factor of the jet.
Inspired by this fact, we use this model to calculate the Lorentz factors of
the four brightest Fermi bursts. The results indicate that the Lorentz factors
are much smaller than that obtained from the ""single-zone"" scenario. The short
GRB 090510 has a minimal Lorentz factor 385, while the three long bursts GRB
080916c, GRB090902b and GRB 090926 have almost the same Lorentz factors, with
an average value near 260. Another interesting result is that, for long bursts,
GeV photons are emitted after the bulk Lorentz factor saturates. For the short
GRB, however, MeV and GeV photons are emitted at the same phase, i.e., either
at the expansion phase or at the coast phase.",1205.3572v3
2012-05-21,"Comment on ""Trouble with the Lorentz Law of Force""","A recent article claims the Lorentz force law is incompatible with special
relativity. The claim is false, and the ""paradox"" on which it is based was
resolved many years ago.",1205.4646v1
2019-04-07,On some integral transforms of Coulomb functions related to three-dimensional proper Lorentz group,"Considering the relationship between two bases in representation space of the
three-dimensional proper Lorentz group, we derive some formulas with integrals
involving Coulomb wave functions, which can be considered as Fourier, Mellin,
$K$-Bessel, Hankel and Mehler-Fock transforms of these functions.",1904.03729v1
2020-05-15,The Lorentzian version of a theorem of Krust,"In Lorentz-Minkowski space, we prove that the conjugate surface of a maximal
graph over a convex domain is also a graph. We provide three proofs of this
result that show a suitable correspondence between maximal surfaces in
Lorentz-Minkowski space and minimal surfaces in Euclidean space.",2005.07657v1
2020-09-04,Lorentz-Shimogaki-Arazy-Cwikel Theorem Revisited,"We present a new approach to Lorentz-Shimogaki and Arazy-Cwikel Theorems
which covers all range of $p,q\in (0,\infty]$ for function spaces and sequence
spaces. As a byproduct, we solve a conjecture of Levitina and the last two
authors.",2009.02145v1
2020-11-02,Non-squareness and local uniform non-squareness properties of Orlicz-Lorentz function spaces endowed with the Orlicz norm,"In this paper the necessary and sufficient conditions were given for
Orlicz-Lorentz function space endowed with the Orlicz norm having
non-squareness and local uniform non-squareness.",2011.00807v1
2021-05-23,Global wellposedness for 2D quasilinear wave without Lorentz,"We consider the two-dimensional quasilinear wave equations with standard
null-form type quadratic nonlinearities. We prove global wellposedness without
using the Lorentz boost vector fields.",2105.10928v1
2021-06-26,Higher genus nonorientable maximal surfaces in the Lorentz-Minkowski 3-space,"We study nonorientable maximal surfaces in Lorentz-Minkowski 3-space. We
prove some existence results for surfaces of this kind with high genus and one
end.",2106.13941v2
2023-01-16,On embedding of Besov spaces of zero smoothness into Lorentz spaces,"We show that the zero smoothness Besov space $B_{p,q}^{0,1}$ does not embed
into the Lorentz space $L_{p,q}$ unless $p=q$; here $p,q\in (1,\infty)$. This
answers negatively a question proposed by O. V. Besov.",2301.06370v1
2023-05-15,Supersymmetry with Lorentz Symmetry Violation,"We study two (massless free field) models, a photon/photino model with a
vector gauge field and a Majorana spinor field, and a Wess-Zumino model. They
each exhibit Lorentz symmetry violation but retain, in an appropriate way, the
supersymmetry correspondance between the particles of the two fields. In
relation to the photon field the Lorentz symmetry violation is of a simple but
non-trivial kind that implies birefringence. In relation to the spinor field
the Lorentz violation is produced by a modification of the Majorana equation
that is a simplified version of more general investigations of Lorentz symmetry
violation of the Dirac equation. In the case of the Wess-Zumino model we retain
the same violation of Lorentz symmetry for the Majorana field and adjust the
propagation of the scalar particles so that they exhibit a corresponding
birefringence. The advantages of the models are that they are straightforward
to investigate completely and both retain the basic aspect of supersymmetry
namely the one-to-one correspondance between bosons and fermions. As a result
of this bottom-up approach it is then possible to construct conserved
supersymmetry charges and investigate their algebraic properties. To some
extent these are similar to those encountered in the case of Lorentz
invariance. However there are differences and in particular non-local terms
appear in the commutation relations of the supersymmetry charges and fields of
the models. We examine carefully the rather intricate nature of the limit back
to Lorentz invariance.",2305.08683v4
2023-07-31,On closed geodesics in Lorentz manifolds,We construct compact Lorentz manifolds without closed geodesics.,2307.16810v3
2024-02-24,Lorentz invariance and quantum mechanics,"Bohmian mechanics and spontaneous collapse models are theories that overcome
the quantum measurement problem. While they are naturally formulated for
non-relativistic systems, it has proven difficult to formulate Lorentz
invariant extensions, primarily due to the inherent non-locality, which is
unavoidable due to Bell's theorem. There are trivial ways to make space-time
theories Lorentz invariant, but the challenge is to achieve what Bell dubbed
``serious Lorentz invariance''. However, this notion is hard to make precise.
This is reminiscent of the debate on the meaning of general invariance in
Einstein's theory of general relativity. The issue there is whether the
requirement of general invariance is physically vacuous (in the sense that any
space-time theory can be made generally invariant) or whether it is a
fundamental physical principle. Here, we want to consider two of the more
promising avenues that have emerged from that debate in order to explore what
serious Lorentz invariance could mean. First, we will consider Anderson's
approach based on the identification of absolute objects. Second, we will
consider a relativity principle for isolated subsystems. Using these criteria,
we will evaluate a number of Lorentz invariant Bohmian models and a spontaneous
collapse model, finding that the latter satisfies both criteria, while there
are some Bohmian models that violate the criteria. However, some Bohmian models
that satisfy both criteria still do not seem seriously Lorentz invariant. While
these notions may hence still not capture exactly what serious Lorentz
invariance ought to be, they clarify what aspects of relativity theory (in
addition to locality) may need to be given up in passing from classical to
quantum theory.",2402.15881v1
2024-03-28,Generalized law of iterated logarithm for the Lorentz gas with infinite horizon,"We obtain a generalized law of iterated logarithm for a class of dependent
processes with superdiffusive behaviour. Our results apply in particular to the
Lorentz gas with infinite horizon.",2403.19582v1
2003-10-29,Comparing Chemical Abundances of the Damped Lya Systems and Metal-Poor Stars,"I briefly draw comparisons between the fields of damped Lya and metal-poor
stellar abundances. In particular, I examine their complementary
age-metallicity relations and comparisons between the damped Lya and dwarf
galaxy abundance patterns. Regarding the latter, I describe a series of
problems concerning associating high z damped Lya systems with present-day
dwarfs.",0310850v1
2006-12-01,Stochastic excitation and damping of solar-type oscillations,"A review on acoustic mode damping and excitation in solar-type stars is
presented. Current models for linear damping rates are discussed in the light
of recent low-degree solar linewidth measurements with emphasis on the
frequency-dependence of damping rates of low-order modes. Recent developments
in stochastic excitation models are reviewed and tested against the latest
high-quality data of solar-like oscillations, such as from alpha Cen A, and
against results obtained from hydrodynamical simulations.",0612024v1
1997-08-11,A theoretical study on the damping of collective excitations in a Bose-Einstein condensate,"We study the damping of low-lying collective excitations of condensates in a
weakly interacting Bose gas model within the framework of imaginary time path
integral. A general expression of the damping rate has been obtained in the low
momentum limit for both the very low temperature regime and the higher
temperature regime. For the latter, the result is new and applicable to recent
experiments. Theoretical predictions for the damping rate are compared with the
experimental values.",9708080v3
1997-09-24,Damping in dilute Bose gases: a mean-field approach,"Damping in a dilute Bose gas is investigated using a mean-field approximation
which describes the coupled oscillations of condensate and non-condensate atoms
in the collisionless regime. Explicit results for both Landau and Beliaev
damping rates are given for non-uniform gases. In the case of uniform systems
we obtain results for the damping of phonons both at zero and finite
temperature. The isothermal compressibility of a uniform gas is also discussed.",9709259v1
2000-09-01,Damped Bogoliubov excitations of a condensate interacting with a static thermal cloud,"We calculate the damping of condensate collective excitations at finite
temperatures arising from the lack of equilibrium between the condensate and
thermal atoms. We neglect the non-condensate dynamics by fixing the thermal
cloud in static equilibrium. We derive a set of generalized Bogoliubov
equations for finite temperatures that contain an explicit damping term due to
collisional exchange of atoms between the two components. We have numerically
solved these Bogoliubov equations to obtain the temperature dependence of the
damping of the condensate modes in a harmonic trap. We compare these results
with our recent work based on the Thomas-Fermi approximation.",0009021v2
2000-11-20,Cavity assisted quasiparticle damping in a Bose-Einstein condensate,"We consider an atomic Bose-Einstein condensate held within an optical cavity
and interacting with laser fields. We show how the interaction of the cavity
mode with the condensate can cause energy due to excitations to be coupled to a
lossy cavity mode, which then decays, thus damping the condensate, how to
choose parameters for damping specific excitations, and how to target a range
of different excitations to potentially produce extremely cold condensates.",0011341v2
2002-12-16,The nonlinear damping of Bose-Einstein condensate oscillations at ultra-low temperatures,"We analyze the damping of the transverse breathing mode in an elongated trap
at ultralow temperatures. The damping occurs due to the parametric resonance
entailing the energy transfer to the longitudinal degrees of freedom. It is
found that the nonlinear coupling between the transverse and discrete
longitudinal modes can result in an anomalous behavior of the damping as a
function of time with the partially reversed pumping of the breathing mode. The
picture revealed explains the results observed in [16].",0212377v2
2004-08-27,Tunable magnetization damping in transition metal ternary alloys,"We show that magnetization damping in Permalloy, Ni80Fe20 (``Py''), can be
enhanced sufficiently to reduce post-switching magnetization precession to an
acceptable level by alloying with the transition metal osmium (Os). The damping
increases monotonically upon raising the Os-concentration in Py, at least up to
9% of Os. Other effects of alloying with Os are suppression of magnetization
and enhancement of in-plane anisotropy. Magnetization damping also increases
significantly upon alloying with the five other transition metals included in
this study (4d-elements: Nb, Ru, Rh; 5d-elements: Ta, Pt) but never as strongly
as with Os.",0408608v1
2005-03-06,Nonlinear damping in nanomechanical beam oscillator,"We investigate the impact of nonlinear damping on the dynamics of a
nanomechanical doubly clamped beam. The beam is driven into nonlinear regime
and the response is measured by a displacement detector. For data analysis we
introduce a nonlinear damping term to Duffing equation. The experiment shows
conclusively that accounting for nonlinear damping effects is needed for
correct modeling of the nanomechanical resonators under study.",0503130v2
2006-05-23,The origin of increase of damping in transition metals with rare earth impurities,"The damping due to rare earth impurities in transition metals is discussed in
the low concentration limit. It is shown that the increase in damping is mainly
due to the coupling of the orbital moments of the rare earth impurities and the
conduction $p$-electrons. It is shown that an itinerant picture for the host
transition ions is needed to reproduce the observed dependence of the damping
on the total angular moment of the rare earths.",0605583v1
2001-05-14,Simplified models of electromagnetic and gravitational radiation damping,"In previous work the authors analysed the global properties of an approximate
model of radiation damping for charged particles. This work is put into context
and related to the original motivation of understanding approximations used in
the study of gravitational radiation damping. It is examined to what extent the
results obtained previously depend on the particular model chosen. Comparisons
are made with other models for gravitational and electromagnetic fields. The
relation of the kinetic model for which theorems were proved to certain
many-particle models with radiation damping is exhibited.",0105045v1
1994-06-07,Damping Rate of a Yukawa Fermion at Finite Temperature,"The damping of a massless fermion coupled to a massless scalar particle at
finite temperature is considered using the Braaten-Pisarski resummation
technique. First the hard thermal loop diagrams of this theory are extracted
and effective Green's functions are constructed. Using these effective Green's
functions the damping rate of a soft Yukawa fermion is calculated. This rate
provides the most simple example for the damping of a soft particle. To leading
order it is proportional to $g^2T$, whereas the one of a hard fermion is of
higher order.",9406242v1
2006-05-02,Moduli decay in the hot early Universe,"We consider moduli fields interacting with thermalized relativistic matter.
We determine the temperature dependence of their damping rate and find it is
dominated by thermal effects in the high temperature regime, i.e. for
temperatures larger than their mass. For a simple scalar model the damping rate
is expressed through the known matter bulk viscosity. The high temperature
damping rate is always smaller than the Hubble rate, so that thermal effects
are not sufficient for solving the cosmological moduli problem.",0605030v2
2006-11-27,Inviscid limit for damped and driven incompressible Navier-Stokes equations in ${{\mathbb R}^2}$,"We consider the zero viscosity limit of long time averages of solutions of
damped and driven Navier-Stokes equations in ${\mathbb R}^2$. We prove that the
rate of dissipation of enstrophy vanishes. Stationary statistical solutions of
the damped and driven Navier-Stokes equations converge to renormalized
stationary statistical solutions of the damped and driven Euler equations.
These solutions obey the enstrophy balance.",0611782v1
2003-09-09,Traveling solitons in the damped driven nonlinear Schrödinger equation,"The well known effect of the linear damping on the moving nonlinear
Schr\""odinger soliton (even when there is a supply of energy via the spatially
homogeneous driving) is to quench its momentum to zero. Surprisingly, the zero
momentum does not necessarily mean zero velocity. We show that two or more
parametrically driven damped solitons can form a complex traveling with zero
momentum at a nonzero constant speed.
  All traveling complexes we have found so far, turned out to be unstable.
Thus, the parametric driving is capable of sustaining the uniform motion of
damped solitons, but some additional agent is required to stabilize it.",0309031v1
2001-11-25,The Landau Damping Effect and Complex-valued Nature of Physical Quantities,"Within the framework of the hypothesis offered by authors about
complex-valued nature of physical quantities, the effect of the Landau damping
has been explored with assumption that not only frequency can be a small
imaginary component but also a wave vector. The numerical solution of the
obtained dispersion equation testifies that uncollisional damping is
accompanied in a certain region of space by antidumping of waves, and in
particular situations antidumping may prevail over damping. It is possible that
this effect may explain the experimental difficulties connected with inhibition
of instabilities of plasma in the problem of controllable thermonuclear fusion.",0111176v1
2005-10-14,Nontrapping arrest of Langmuir wave damping near the threshold amplitude,"Evolution of a Langmuir wave is studied numerically for finite amplitudes
slightly above the threshold which separates damping from nondamping cases.
Arrest of linear damping is found to be a second-order effect due to ballistic
evolution of perturbations, resonant power transfer between field and
particles, and organization of phase space into a positive slope for the
average distribution function $f_{av}$ around the resonant wave phase speed
$v_\phi$. Near the threshold trapping in the wave potential does not arrest
damping or saturate the subsequent growth phase.",0510131v3
2000-06-22,Decoherence and Entanglement in Two-mode Squeezed Vacuum States,"I investigate the decoherence of two-mode squeezed vacuum states by analyzing
the relative entropy of entanglement. I consider two sources of decoherence:
(i) the phase damping and (ii) the amplitude damping due to the coupling to the
thermal environment. In particular, I give the exact value of the relative
entropy of entanglement for the phase damping model. For the amplitude damping
model, I give an upper bound for the relative entropy of entanglement, which
turns out to be a good approximation for the entanglement measure in usual
experimental situations.",0006100v1
2006-08-02,Damped Population Oscillation in a Spontaneously Decaying Two-Level Atom Coupled to a Monochromatic Field,"We investigate the time evolution of atomic population in a two-level atom
driven by a monochromatic radiation field, taking spontaneous emission into
account. The Rabi oscillation exhibits amplitude damping in time caused by
spontaneous emission. We show that the semiclassical master equation leads in
general to an overestimation of the damping rate and that a correct
quantitative description of the damped Rabi oscillation can thus be obtained
only with a full quantum mechanical theory.",0608020v1
2006-11-23,Analytical solutions for two-level systems with damping,"A method is proposed to transform any analytic solution of the Bloch equation
into an analytic solution of the Landau-Lifshitz-Gilbert equation. This allows
for the analytical description of the dynamics of a two level system with
damping. This method shows that damping turns the linear Schr\""{o}dinger
equation of a two-level system into a nonlinear Schr\""{o}dinger equation. As
applications, it is shown that damping has a relatively mild influence on
self-induced transparency but destroys dynamical localization.",0611238v1
2007-06-12,Gilbert and Landau-Lifshitz damping in the presense of spin-torque,"A recent article by Stiles et al. (cond-mat/0702020) argued in favor of the
Landau-Lifshitz damping term in the micromagnetic equations of motion over that
of the more commonly accepted Gilbert damping form. Much of their argument
revolved around spin-torque driven domain wall motion in narrow magnetic wires,
since the presence of spin-torques can more acutely draw a distinction between
the two forms of damping. In this article, the author uses simple arguments and
examples to offer an alternative point of view favoring Gilbert.",0706.1736v1
2007-08-24,Enhancement of the Gilbert damping constant due to spin pumping in noncollinear ferromagnet/nonmagnet/ferromagnet trilayer systems,"We analyzed the enhancement of the Gilbert damping constant due to spin
pumping in non-collinear ferromagnet / non-magnet / ferromagnet trilayer
systems. We show that the Gilbert damping constant depends both on the
precession angle of the magnetization of the free layer and on the direction of
the magntization of the fixed layer. We find the condition to be satisfied to
realize strong enhancement of the Gilbert damping constant.",0708.3323v1
2007-08-28,Linear frictional forces cause orbits to neither circularize nor precess,"For the undamped Kepler potential the lack of precession has historically
been understood in terms of the Runge-Lenz symmetry. For the damped Kepler
problem this result may be understood in terms of the generalization of Poisson
structure to damped systems suggested recently by Tarasov[1]. In this
generalized algebraic structure the orbit-averaged Runge-Lenz vector remains a
constant in the linearly damped Kepler problem to leading order in the damping
coe",0708.3827v3
2008-04-04,Inhomogeneous Gilbert damping from impurities and electron-electron interactions,"We present a unified theory of magnetic damping in itinerant electron
ferromagnets at order $q^2$ including electron-electron interactions and
disorder scattering. We show that the Gilbert damping coefficient can be
expressed in terms of the spin conductivity, leading to a Matthiessen-type
formula in which disorder and interaction contributions are additive. In a weak
ferromagnet regime, electron-electron interactions lead to a strong enhancement
of the Gilbert damping.",0804.0820v2
2008-12-11,Frequency-dependent Drude damping in Casimir force calculations,"The Casimir force is calculated between Au thin films that are described by a
Drude model with a frequency dependent damping function. The model parameters
are obtained from available experimental data for Au thin films. Two cases are
considered; annealed and nonannealed films that have a different damping
function. Compared with the calculations using a Drude model with a constant
damping parameter, we observe changes in the Casimir force of a few percent.
This behavior is only observed in films of no more than 300 $\AA$ thick.",0812.2209v1
2008-12-18,Dipole Oscillations of a Fermi Gas in a Disordered Trap: Damping and Localization,"We theoretically study the dipole oscillations of an ideal Fermi gas in a
disordered trap. We show that even weak disorder induces strong damping of the
oscillations and we identify a metal-insulator crossover. For very weak
disorder, we show that damping results from a dephasing effect related to weak
random perturbations of the energy spectrum. For increasing disorder, we show
that the Fermi gas crosses over to an insulating regime characterized by
strong-damping due to the proliferation of localized states.",0812.3501v2
2009-03-11,Confronting the damping of the baryon acoustic oscillations with observation,"We investigate the damping of the baryon acoustic oscillations in the matter
power spectrum due to the quasinonlinear clustering and redshift-space
distortions by confronting the models with the observations of the Sloan
Digital Sky Survey luminous red galaxy sample. The chi-squared test suggests
that the observed power spectrum is better matched by models with the damping
of the baryon acoustic oscillations rather than the ones without the damping.",0903.1883v1
2009-04-10,Spectral deviations for the damped wave equation,"We prove a Weyl-type fractal upper bound for the spectrum of the damped wave
equation, on a negatively curved compact manifold. It is known that most of the
eigenvalues have an imaginary part close to the average of the damping
function. We count the number of eigenvalues in a given horizontal strip
deviating from this typical behaviour; the exponent that appears naturally is
the `entropy' that gives the deviation rate from the Birkhoff ergodic theorem
for the geodesic flow. A Weyl-type lower bound is still far from reach; but in
the particular case of arithmetic surfaces, and for a strong enough damping, we
can use the trace formula to prove a result going in this direction.",0904.1736v1
2009-10-26,Pressure Fronts in 1D Damped Nonlinear Lattices,"The propagation of pressure fronts (impact solutions) in 1D chains of atoms
coupled by anharmonic potentials between nearest neighbor and submitted to
damping forces preserving uniform motion, is investigated. Travelling fronts
between two regions at different uniform pressures are found numerically and
well approximate analytically. It is proven that there are three analytical
relations between the impact velocity, the compression, the front velocity and
the energy dissipation which only depend on the coupling potential and are
\textit{independent} of the damping. Such travelling front solutions cannot
exist without damping.",0910.4890v1
2009-11-05,Bloch oscillations in lattice potentials with controlled aperiodicity,"We numerically investigate the damping of Bloch oscillations in a
one-dimensional lattice potential whose translational symmetry is broken in a
systematic manner, either by making the potential bichromatic or by introducing
scatterers at distinct lattice sites. We find that the damping strongly depends
on the ratio of lattice constants in the bichromatic potential, and that even a
small concentration of scatterers can lead to strong damping. Moreover,
mean-field interactions are able to counteract aperiodicity-induced damping of
Bloch oscillations.",0911.1108v3
2010-01-12,Decoherence and damping in ideal gases,"The particle and current densities are shown to display damping and undergo
decoherence in ideal quantum gases. The damping is read off from the equations
of motion reminiscent of the Navier-Stokes equations and shows some formal
similarity with Landau damping. The decoherence leads to consistent density and
current histories with characteristic length and time scales given by the ideal
gas.",1001.1803v2
2010-06-01,Recent Progress on a Manifold Damped and Detuned Structure for CLIC,"A damped detuned structure for the main X-band linacs of CLIC is being
investigated as an alternative design to the present baseline heavily damped
structure. In our earlier designs we studied detuned structures, operating at
11.994 GHz, with a range of dipole bandwidths in order to ensure the structure
satisfies beam dynamics and rf breakdown constraints. Here we report on the
development of a damped and detuned structure which satisfies both constraints.
Preparations for high power testing of the structure are also discussed",1006.0087v1
2010-07-21,Finite temperature damping of collective modes of a BCS-BEC crossover superfluid,"A new mechanism is proposed to explain the puzzling damping of collective
excitations, which was recently observed in the experiments of strongly
interacting Fermi gases below the superfluid critical temperature on the
fermionic (BCS) side of Feshbach resonance. Sound velocity, superfluid density
and damping rate are calculated with effective field theory. We find that a
dominant damping process is due to the interaction between superfluid phonons
and thermally excited fermionic quasiparticles, in contrast to the previously
proposed pair-breaking mechanism. Results from our effective model are compared
quantitatively with recent experimental findings, showing a good agreement.",1007.3694v2
2010-08-04,Confinement induced by fermion damping in three-dimensional QED,"The three-dimensional non-compact QED is known to exhibit weak confinement
when fermions acquire a finite mass via the mechanism of dynamical chiral
symmetry breaking. In this paper, we study the effect of fermion damping caused
by elastic scattering on the classical potential between fermions. By
calculating the vacuum polarization function that incorporates the fermion
damping effect, we show that fermion damping can induce a weak confinement even
when the fermions are massless and the chiral symmetry is not broken.",1008.0736v2
2011-06-22,Highly Damped Quasinormal Modes and the Small Scale Structure of Quantum Corrected Black Hole Exteriors,"Quasinormal modes provide valuable information about the structure of
spacetime outside a black hole. There is also a conjectured relationship
between the highly damped quasinormal modes and the semi-classical spectrum of
the horizon area/entropy. In this paper, we show that for spacetimes
characterized by more than one scale, the ""infinitely damped"" modes in
principle probe the structure of spacetime outside the horizon at the shortest
length scales. We demonstrate this with the calculation of the highly damped
quasinormal modes of the non-singular, single horizon, quantum corrected black
hole derived in [14].",1106.4357v1
2012-02-20,Simple Non-Markovian Microscopic Models for the Depolarizing Channel of a Single Qubit,"The archetypal one-qubit noisy channels ---depolarizing, phase-damping and
amplitude-damping channels--- describe both Markovian and non-Markovian
evolution. Simple microscopic models for the depolarizing channel, both
classical and quantum, are considered. Microscopic models which describe phase
damping and amplitude damping channels are briefly reviewed.",1202.4210v4
2012-06-14,Damping of optomechanical disks resonators vibrating in air,"We report on miniature GaAs disk optomechanical resonators vibrating in air
in the radiofrequency range. The flexural modes of the disks are studied by
scanning electron microscopy and optical interferometry, and correctly modeled
with the elasticity theory for annular plates. The mechanical damping is
systematically measured, and confronted with original analytical models for air
damping. Formulas are derived that correctly reproduce both the mechanical
modes and the damping behavior, and can serve as design tools for
optomechanical applications in fluidic environment.",1206.3032v1
2012-07-09,A Generalized Interpolation Inequality and its Application to the Stabilization of Damped Equations,"In this paper, we establish a generalized H{\""o}lder's or interpolation
inequality for weighted spaces in which the weights are non-necessarily
homogeneous. We apply it to the stabilization of some damped wave-like
evolution equations. This allows obtaining explicit decay rates for smooth
solutions for more general classes of damping operators. In particular, for
$1-d$ models, we can give an explicit decay estimate for pointwise damping
mechanisms supported on any strategic point.",1207.2030v2
2012-07-10,Conformation dependent damping and generalization of fluctuation-dissipation relation,"Damping on an object generally depends on its conformation (shape size etc.).
We consider the Langevin dynamics of a model system with a conformation
dependent damping and generalize the fluctuation dissipation relation to fit in
such a situation. We derive equilibrium distribution function for such a case
which converges to the standard Boltzmann form at the limit of uniform damping.
The results can have implications, in general, for barrier overcoming processes
where standard Boltzmann statistics is slow.",1207.2218v2
2012-10-30,On algebraic damping close to inhomogeneous Vlasov equilibria in multi-dimensional spaces,"We investigate the asymptotic damping of a perturbation around inhomogeneous
stable stationary states of the Vlasov equation in spatially multi-dimensional
systems. We show that branch singularities of the Fourier-Laplace transform of
the perturbation yield algebraic dampings. In two spatial dimensions, we
classify the singularities and compute the associated damping rate and
frequency. This 2D setting also applies to spherically symmetric
self-gravitating systems. We validate the theory using a toy model and an
advection equation associated with the isochrone model, a model of spherical
self-gravitating systems.",1210.8040v1
2013-04-07,Phenomenological model of anomalous magnon softening and damping in half-metallic manganites,"To describe anomalous zone-boundary softening and damping of magnons in
manganites we present a phenomenological two-fluid model containing
ferromagnetic Fermi-liquid and non-Fermi-liquid components. The Fermi-liquid
component accounts for softening of zone-boundary magnons and for the Landau
damping of magnons in the Stoner continuum arising at low frequencies due to
zero-point effects. Coupling of the Fermi-liquid and non-Fermi-liquid fluids
yields conventional long wavelength magnons damped due to their coupling with
longitudinal spin fluctuations.",1304.1983v1
2013-04-25,Determination of Transverse Density Structuring from Propagating MHD Waves in the Solar Atmosphere,"We present a Bayesian seismology inversion technique for propagating
magnetohydrodynamic (MHD) transverse waves observed in coronal waveguides. The
technique uses theoretical predictions for the spatial damping of propagating
kink waves in transversely inhomogeneous coronal waveguides. It combines wave
amplitude damping length scales along the waveguide with theoretical results
for resonantly damped propagating kink waves to infer the plasma density
variation across the oscillating structures. Provided the spatial dependence of
the velocity amplitude along the propagation direction is measured and the
existence of two different damping regimes is identified, the technique would
enable us to fully constrain the transverse density structuring, providing
estimates for the density contrast and its transverse inhomogeneity length
scale.",1304.6869v1
2013-07-08,Optimal decay rate of the bipolar Euler-Poisson system with damping in $\mathbb{R}^3$,"By rewriting a bipolar Euler-Poisson equations with damping into an Euler
equation with damping coupled with an Euler-Poisson equation with damping, and
using a new spectral analysis, we obtain the optimal decay results of the
solutions in $L^2$-norm, which improve theose in \cite{Li3, Wu3}. More
precisely, the velocities $u_1,u_2$ decay at the $L^2-$rate $(1+t)^{-{5}{4}}$,
which is faster than the normal $L^2-$rate $(1+t)^{-{3}{4}}$ for the Heat
equation and the Navier-Stokes equations. In addition, the disparity of two
densities $\rho_1-\rho_2$ and the disparity of two velocities $u_1-u_2$ decay
at the $L^2$-rate $(1+t)^{-2}$.",1307.2081v1
2013-07-27,Symmetry considerations on radiation damping,"It is well known that a direct Lagrangian description of radiation damping is
still missing. In this paper we will use a specific approach of this problem
which is the standard way to treat the radiation damping problem. The
objectives here are to construct: a N=2 supersymmetric extension for the model
describing the radiation damping on the noncommutative plane with electric and
magnetic interactions; a dualization analysis of the original action; the
supercharge algebra and the total Hamiltonian for the system.",1307.7319v1
2014-02-10,Damping of a nanocantilever by paramagnetic spins,"We compute damping of mechanical oscillations of a cantilever that contains
flipping paramagnetic spins. This kind of damping is mandated by the dynamics
of the total angular momentum, spin + mechanical. Rigorous expression for the
damping rate is derived in terms of measurable parameters. The effect of spins
on the quality factor of the cantilever can be significant in cantilevers of
small length that have large concentration of paramagnetic spins of atomic
and/or nuclear origin.",1402.2326v1
2014-02-20,Long-time behavior of solutions of a BBM equation with generalized damping,"We study the long-time behavior of the solution of a damped BBM equation $u_t
+ u_x - u_{xxt} + uu_x + \mathscr{L}_{\gamma}(u) = 0$. The proposed dampings
$\mathscr{L}_{\gamma}$ generalize standards ones, as parabolic
($\mathscr{L}_{\gamma}(u)=-\Delta u$) or weak damping
($\mathscr{L}_{\gamma}(u)=\gamma u$) and allows us to consider a greater range.
After establish the local well-posedness in the energy space, we investigate
some numerical properties.",1402.5009v1
2014-02-24,N=2 supersymmetric radiation damping problem on a noncommutative plane,"It is well known that a direct Lagrangian description of radiation damping is
still missing. In this paper a specific approach of this problem was used,
which is the standard way to treat the radiation damping problem. A $N=2$
supersymmetric extension for the model describing the radiation damping on the
noncommutative plane with electric and magnetic interactions was obtained. The
entire supercharge algebra and the total Hamiltonian for the system were
analyzed. Finally, noncommutativity features were introduced and its
consequences were explored..",1402.6996v1
2014-11-03,Renormalized solutions to the continuity equation with an integrable damping term,"We consider the continuity equation with a nonsmooth vector field and a
damping term. In their fundamental paper, DiPerna and Lions proved that, when
the damping term is bounded in space and time, the equation is well posed in
the class of distributional solutions and the solution is transported by
suitable characteristics of the vector field. In this paper, we prove existence
and uniqueness of renormalized solutions in the case of an integrable damping
term, employing a new logarithmic estimate inspired by analogous ideas of
Ambrosio, Lecumberry, and Maniglia, Crippa and De Lellis in the Lagrangian
case.",1411.0451v1
2015-02-07,Landau Damping in a Mixture of Bose and Fermi Superfluids,"We study the Landau damping in Bose-Fermi superfluid mixture at finite
temperature. We find that at low temperature, the Landau damping rate will be
exponentially suppressed at both the BCS side and the BEC side of Fermi
superfluid. The momentum dependence of the damping rate is obtained, and it is
quite different from the BCS side to the BEC side. The relations between our
result and collective mode experiment in the recently realized Bose-Fermi
superfluid mixture are also discussed.",1502.02116v1
2015-03-20,Applying a formula for generator redispatch to damp interarea oscillations using synchrophasors,"If an interarea oscillatory mode has insufficient damping, generator
redispatch can be used to improve its damping. We explain and apply a new
analytic formula for the modal sensitivity to rank the best pairs of generators
to redispatch. The formula requires some dynamic power system data and we show
how to obtain that data from synchrophasor measurements. The application of the
formula to damp interarea modes is explained and illustrated with interarea
modes of the New England 10-machine power system.",1503.06144v2
2016-01-21,Codeword Stabilized Quantum Codes for Asymmetric Channels,"We discuss a method to adapt the codeword stabilized (CWS) quantum code
framework to the problem of finding asymmetric quantum codes. We focus on the
corresponding Pauli error models for amplitude damping noise and phase damping
noise. In particular, we look at codes for Pauli error models that correct one
or two amplitude damping errors. Applying local Clifford operations on graph
states, we are able to exhaustively search for all possible codes up to length
$9$. With a similar method, we also look at codes for the Pauli error model
that detect a single amplitude error and detect multiple phase damping errors.
Many new codes with good parameters are found, including nonadditive codes and
degenerate codes.",1601.05763v1
2016-02-08,On Boundary Damped Inhomogeneous Timoshenko Beams and Related Problems,"We consider the model equations for the Timoshenko beam as a first order
system in the framework of evolutionary equations. The focus is on boundary
damping, which is implemented as a dynamic boundary condition. A change of
material laws allows to include a large class of cases of boundary damping. By
choosing a particular material law, it is shown that the first order approach
to Sturm-Liouville problems with boundary damping is also covered.",1602.02521v1
2016-02-13,Diffusion phenomena for the wave equation with space-dependent damping in an exterior domain,"In this paper, we consider the asymptotic behavior of solutions to the wave
equation with space-dependent damping in an exterior domain. We prove that when
the damping is effective, the solution is approximated by that of the
corresponding heat equation as time tends to infinity. Our proof is based on
semigroup estimates for the corresponding heat equation and weighted energy
estimates for the damped wave equation. The optimality of the decay late for
solutions is also established.",1602.04318v1
2016-02-29,Robust quantum state recovery from amplitude damping within a mixed states framework,"Due to the interaction with the environment, a quantum state is subjected to
decoherence which becomes one of the biggest problems for practical quantum
computation. Amplitude damping is one of the most important decoherence
processes. Here, we show that general two-qubit mixed states undergoing an
amplitude damping can be almost completely restored using a reversal procedure.
This reversal procedure through CNOT and Hadamard gates, could also protect the
entanglement of two-qubit mixed states, when it undergoes general amplitude
damping. Moreover, in the presence of uncertainty in the underlying system, we
propose a robust recovering method with optimal characteristics of the problem.",1602.08865v1
2016-07-21,Protecting and enhancing spin squeezing under decoherence using weak measurement,"We propose an efficient method to protect spin squeezing under the action of
amplitude-damping, depolarizing and phase-damping channels based on measurement
reversal from weak measurement, and consider an ensemble of N independent
spin-1/2 particles with exchange symmetry. We find that spin squeezing can be
enhanced greatly under three different decoherence channels and spin-squeezing
sudden death (SSSD) can be avoided undergoing amplitude damping and
phase-damping channels.",1607.06530v2
2016-09-05,Remarks on an elliptic problem arising in weighted energy estimates for wave equations with space-dependent damping term in an exterior domain,"This paper is concerned with weighted energy estimates and diffusion
phenomena for the initial-boundary problem of the wave equation with
space-dependent damping term in an exterior domain. In this analysis, an
elliptic problem was introduced by Todorova and Yordanov. This attempt was
quite useful when the coefficient of the damping term is radially symmetric. In
this paper, by modifying their elliptic problem, we establish weighted energy
estimates and diffusion phenomena even when the coefficient of the damping term
is not radially symmetric.",1609.01063v2
2017-03-09,Long-time dynamics of the strongly damped semilinear plate equation in $\mathbb{R}^{n}$,"We investigate the initial-value problem for the semilinear plate equation
containing localized strong damping, localized weak damping and nonlocal
nonlinearity. We prove that if nonnegative damping coefficients are strictly
positive almost everywhere in the exterior of some ball and the sum of these
coefficients is positive a.e. in $%
  \mathbb{R}
  ^{n}$, then the semigroup generated by the considered problem possesses a
global attractor in $H^{2}\left(
  \mathbb{R}
  ^{n}\right) \times L^{2}\left(
  \mathbb{R}
  ^{n}\right) $. We also establish boundedness of this attractor in $
H^{3}\left(
  \mathbb{R}
  ^{n}\right) \times H^{2}\left(
  \mathbb{R} ^{n}\right) $.",1703.03485v2
2017-08-20,Radiation Damping of a Polarizable Particle,"A polarizable body moving in an external electromagnetic field will slow
down. This effect is referred to as radiation damping and is analogous to
Doppler cooling in atomic physics. Using the principles of special relativity
we derive an expression for the radiation damping force and find that it solely
depends on the scattered power. The cooling of the particle's center-of-mass
motion is balanced by heating due to radiation pressure shot noise, giving rise
to an equilibrium that depends on the ratio of the field's frequency and the
particle's mass. While damping is of relativistic nature heating has it's roots
in quantum mechanics.",1708.06628v1
2018-10-26,Drastic Reduction of Plasmon Damping in Two-Dimensional Electron Disks,"The plasmon damping has been investigated using resonant microwave absorption
of two-dimensional electrons in disks with different diameters. We have found
an unexpected drastic reduction of the plasmon damping in the regime of strong
retardation. This finding implies large delocalization of retarded plasmon
field outside the plane of the two-dimensional electron system. A universal
relation between the damping of plasmon polariton waves and retardation
parameter is reported.",1811.01040v1
2010-05-14,The effect of spin magnetization in the damping of electron plasma oscillations,"The effect of spin of particles in the propagation of plasma waves is studied
using a semi-classical kinetic theory for a magnetized plasma. We focus in the
simple damping effects for the electrostatic wave modes besides Landau damping.
Without taking into account more quantum effects than spin contribution to
Vlasov's equation, we show that spin produces a new damping or instability
which is proportional to the zeroth order magnetization of the system. This
correction depends on the electromagnetic part of the wave which is coupled
with the spin vector.",1005.2573v1
2016-11-16,Finite-orbit-width effects on the geodesic acoustic mode in the toroidally rotating tokamak plasma,"The Landau damping of geodesic acoustic mode (GAM) in a torodial rotating
tokamak plasma is analytically investigated by taking into account the
finite-orbit-width (FOW) resonance effect to the 3rd order. The analytical
result is shown to agree well with the numerical solution. The dependence of
the damping rate on the toroidal Mach number $M$ relies on $k_r \rho_i$. For
sufficiently small $k_r \rho_i$, the damping rate monotonically decreases with
$M$. For relatively large $k_r \rho_i$, the damping rate increases with $M$
until approaching the maximum and then decreases with $M$.",1611.05168v1
2017-04-21,The Effects of Rolling Deformation and Annealing Treatment on Damping Capacity of 1200 Aluminium Alloy,"Annealing treatment is an important step of rolling deformation that
contributes to microstructural evolution and leads to the significant changes
in damping capacity. Damping capacities were analyzed in the parallel to
rolling direction at 1 and 10 Hz respectively. It was found that severe plastic
deformation at 40 percent reduction has lower damping capacity compared to that
of 30 percent and 20 percent reductions respectively. The microstructural
results show that the grains of as rolled alloys were changed to almost
equiaxed structures after a rolling reduction at 40 percent reduction.",1704.07362v1
2018-05-10,Dynamics of coherence-induced state ordering under Markovian channels,"We study the dynamics of coherence-induced state ordering under incoherent
channels, particularly four specific Markovian channels: $-$ amplitude damping
channel, phase damping channel, depolarizing channel and bit flit channel for
single-qubit states. We show that the amplitude damping channel, phase damping
channel, and depolarizing channel do not change the coherence-induced state
ordering by $l_1$ norm of coherence, relative entropy of coherence, geometric
measure of coherence, and Tsallis relative $\alpha$-entropies, while the bit
flit channel does change for some special cases.",1805.03898v1
2016-05-23,Large time behaivor of global solutions to nonlinear wave equations with frictional and viscoelastic damping terms,"In this paper, we study the Cauchy problem for a nonlinear wave equation with
frictional and viscoelastic damping terms. As is pointed out by [8], in this
combination, the frictional damping term is dominant for the viscoelastic one
for the global dynamics of the linear equation. In this note we observe that if
the initial data is small, the frictional damping term is again dominant even
in the nonlinear equation case. In other words, our main result is diffusion
phenomena: the solution is approximated by the heat kernel with a suitable
constant. Our proof is based on several estimates for the corresponding linear
equations.",1605.07232v1
2016-08-02,Ferromagnetic Damping/Anti-damping in a Periodic 2D Helical surface; A Non-Equilibrium Keldysh Green Function Approach,"In this paper, we investigate theoretically the spin-orbit torque as well as
the Gilbert damping for a two band model of a 2D helical surface state with a
Ferromagnetic (FM) exchange coupling. We decompose the density matrix into the
Fermi sea and Fermi surface components and obtain their contributions to the
electronic transport as well as the spin-orbit torque (SOT). Furthermore, we
obtain the expression for the Gilbert damping due to the surface state of a 3D
Topological Insulator (TI) and predicted its dependence on the direction of the
magnetization precession axis.",1608.00984v2
2017-07-12,Isolated resonances and nonlinear damping,"We analyze isolated resonance curves (IRCs) in a single-degree-of-freedom
system with nonlinear damping. The adopted procedure exploits singularity
theory in conjunction with the harmonic balance method. The analysis unveils a
geometrical connection between the topology of the damping force and IRCs.
Specifically, we demonstrate that extremas and zeros of the damping force
correspond to the appearance and merging of IRCs.",1707.03561v2
2017-07-25,Best exponential decay rate of energy for the vectorial damped wave equation,"The energy of solutions of the scalar damped wave equation decays uniformly
exponentially fast when the geometric control condition is satisfied. A theorem
of Lebeau [leb93] gives an expression of this exponential decay rate in terms
of the average value of the damping terms along geodesics and of the spectrum
of the infinitesimal generator of the equation. The aim of this text is to
generalize this result in the setting of a vectorial damped wave equation on a
Riemannian manifold with no boundary. We obtain an expression analogous to
Lebeau's one but new phenomena like high frequency overdamping arise in
comparison to the scalar setting. We also prove a necessary and sufficient
condition for the strong stabilization of the vectorial wave equation.",1707.07893v1
2017-12-31,Stabilization of the weakly coupled wave-plate system with one internal damping,"This paper is addressed to a stabilization problem of a system coupled by a
wave and a Euler-Bernoulli plate equation. Only one equation is supposed to be
damped. Under some assumption about the damping and the coupling terms, it is
shown that sufficiently smooth solutions of the system decay logarithmically at
infinity without any geometric conditions on the effective damping domain. The
proofs of these decay results rely on the interpolation inequalities for the
coupled elliptic-parabolic systems and make use of the estimate of the
resolvent operator for the coupled system. The main tools to derive the desired
interpolation inequalities are global Carleman estimates.",1801.00232v1
2018-09-05,Damping estimates for oscillatory integral operators with real-analytic phases and its applications,"In this paper, we investigate sharp damping estimates for a class of one
dimensional oscillatory integral operators with real-analytic phases. By
establishing endpoint estimates for suitably damped oscillatory integral
operators, we are able to give a new proof of the sharp $L^p$ estimates which
have been proved by Xiao in Endpoint estimates for one-dimensional oscillatory
integral operators, \emph{Advances in Mathematics}, \textbf{316}, 255-291
(2017). The damping estimates obtained in this paper are of independent
interest.",1809.01298v2
2018-09-26,"Global Attractor For Weakly Damped, Forced Mkdv Equation Below Energy Space","We prove the existence of the global attractor in $ \dot H^s$, $s > 11/12$
for the weakly damped and forced mKdV on the one dimensional torus. The
existence of global attractor below the energy space has not been known, though
the global well-posedness below the energy space is established. We directly
apply the I-method to the damped and forced mKdV, because the Miura
transformation does not work for the mKdV with damping and forcing terms. We
need to make a close investigation into the trilinear estimates involving
resonant frequencies, which are different from the bilinear estimates
corresponding to the KdV.",1809.09787v1
2018-10-03,Damped Oscillator with delta-kicked frequency in probability representation of quantum mechanic,"We obtain the tomogram of squeezed correlated states of a quantum parametric
damped oscillator in an explicit form. We study the damping within the
framework of the Caldirola--Kanai model and chose the parametric excitation in
the form of a very short pulse simulated by a delta-kick of frequency; the
squeezing phenomenon is reviewed. The cases of strong and weak damping are
investigated.",1810.01672v1
2020-01-02,On Echo Chains in Landau damping: Self-similar Solutions and Gevrey 3 as a Linear Stability Threshold,"We show that the linearized Vlasov-Poisson equations around self-similar
non-homogeneous states near zero contain the full plasma echo mechanism,
yielding Gevrey 3 as a critical stability class. Moreover, here Landau damping
may persist despite blow-up: We construct a critical Gevrey regularity class in
which the force field converges in $L^2$. Thus, on the one hand, the physical
phenomenon of Landau damping holds. On the other hand, the density diverges to
infinity in Sobolev regularity. Hence, ``strong damping'' cannot hold.",2001.00513v1
2020-01-21,Pseudospectra of the damped wave equation with unbounded damping,"We analyze pseudospectra of the generator of the damped wave equation with
unbounded damping. We show that the resolvent norm diverges as $\Re z \to -
\infty$. The highly non-normal character of the operator is a robust effect
preserved even when a strong potential is added. Consequently, spectral
instabilities and other related pseudospectral effects are present.",2001.07767v1
2020-02-09,The damped wave equation with singular damping,"We analyze the spectral properties and peculiar behavior of solutions of a
damped wave equation on a finite interval with a singular damping of the form
$\alpha/x$, $\alpha>0$. We establish the exponential stability of the semigroup
for all positive $\alpha$, and determine conditions for the spectrum to consist
of a finite number of eigenvalues. As a consequence, we fully characterize the
set of initial conditions for which there is extinction of solutions in finite
time. Finally, we propose two open problems related to extremal decay rates of
solutions.",2002.03440v1
2020-12-28,Nonlinear modal analysis of nonconservative systems: Extension of the periodic motion concept,"As the motions of nonconservative autonomous systems are typically not
periodic, the definition of nonlinear modes as periodic motions cannot be
applied in the classical sense. In this paper, it is proposed 'make the motions
periodic' by introducing an additional damping term of appropriate sign and
magnitude. It is shown that this generalized definition is particularly suited
to reflect the periodic vibration behavior induced by harmonic external forcing
or negative linear damping. In a large range, the energy dependence of modal
frequency, damping ratio and stability is reproduced well. The limitation to
isolated or weakly-damped modes is discussed.",2101.00949v1
2012-05-11,On radiative damping in plasma-based accelerators,"Radiative damping in plasma-based electron accelerators is analyzed. The
electron dynamics under combined influence of the constant accelerating force
and the classical radiation reaction force is studied. It is shown that
electron acceleration cannot be limited by radiation reaction. If initially the
accelerating force was stronger than the radiation reaction force then the
electron acceleration is unlimited. Otherwise the electron is decelerated by
radiative damping up to a certain instant of time and then accelerated without
limits. Regardless of the initial conditions the infinite-time asymptotic
behavior of an electron is governed by self-similar solution providing
unlimited acceleration. The relative energy spread induced by the radiative
damping decreases with time in the infinite-time limit.",1205.2436v1
2017-09-13,Energy decay for the Klein-Gordon equation with highly oscillating damping,"We consider the free Klein-Gordon equation with periodic damping. We show on
this simple model that if the usual geometric condition holds then the decay of
the energy is uniform with respect to the oscillations of the damping, and in
particular the size of the derivatives do not play any role. We also show that
without geometric condition the polynomial decay of the energy is even slightly
better for a highly oscillating damping. To prove these estimates we provide a
parameter dependent version of well known results of semigroup theory.",1709.04197v1
2017-11-01,Analysis of A Splitting Scheme for Damped Stochastic Nonlinear Schrödinger Equation with Multiplicative Noise,"In this paper, we investigate the damped stochastic nonlinear
Schr\""odinger(NLS) equation with multiplicative noise and its splitting-based
approximation. When the damped effect is large enough, we prove that the
solutions of the damped stochastic NLS equation and the splitting scheme are
exponential stable and possess some exponential integrability.
  These properties lead that the strong order of the scheme is $\frac 12$ and
independent of time. Meanwhile, we analyze the regularity of the Kolmogorov
equation with respect to the equation. As a consequence, the weak order of the
scheme is shown to be twice the strong order and independent of time.",1711.00516v2
2018-08-19,Sharp lifespan estimates of blowup solutions to semilinear wave equations with time-dependent effective damping,"We consider the initial value problem for the semilinear wave equation with
time-dependent effective damping. The interest is the behavior of lifespan of
solutions in view of the asymptotic profile of the damping as $t\to \infty$.
The result of this paper is the sharp lifespan estimates of blowup solutions
for general time-dependent damping including threshold cases between effective
and overdamping.",1808.06189v2
2019-01-05,Cauchy problem for thermoelastic plate equations with different damping mechanisms,"In this paper we study Cauchy problem for thermoelastic plate equations with
friction or structural damping in $\mathbb{R}^n$, $n\geq1$, where the heat
conduction is modeled by Fourier's law. We explain some qualitative properties
of solutions influenced by different damping mechanisms. We show which damping
in the model has a dominant influence on smoothing effect, energy estimates,
$L^p-L^q$ estimates not necessary on the conjugate line, and on diffusion
phenomena. Moreover, we derive asymptotic profiles of solutions in a framework
of weighted $L^1$ data. In particular, sharp decay estimates for lower bound
and upper bound of solutions in the $\dot{H}^s$ norm ($s\geq0$) are shown.",1901.01423v2
2019-03-04,Damping of cosmological tensor modes in Horndeski theories after GW170817,"This paper investigates the propagation of cosmological gravitational waves
interacting with free-streaming neutrinos within the context of Horndeski
theories of gravity constrained by the detection of GW170817. We apply the
theory of cosmological perturbations to explicitly derive the
Einstein-Boltzmann equation for the damped propagation of first-order
transverse traceless gravitational waves. In contrast to general relativity, we
argue that modified gravity can give rise to non-vanishing free-streaming
damping effects during the cosmological matter dominated era. We also provide
an analytic formula for the main multipole order with which modified gravity
and free-streaming neutrinos damp the variety of tensor correlation functions
of the cosmic microwave background.",1903.01502v2
2019-04-24,On the Energy Decay Rate of the Fractional Wave Equation on $\mathbb{R}$ with Relatively Dense Damping,"We establish upper bounds for the decay rate of the energy of the damped
fractional wave equation when the averages of the damping coefficient on all
intervals of a fixed length are bounded below. If the power of the fractional
Laplacian, $s$, is between 0 and 2, the decay is polynomial. For $s \ge 2$, the
decay is exponential. Second, we show that our assumption on the damping is
necessary for the energy to decay exponentially.",1904.10946v3
2019-08-22,Damping of the Anderson-Bogolyubov mode by spin and mass imbalance in Fermi mixtures,"We study the temporally nonlocal contributions to the gradient expansion of
the pair fluctuation propagator for spin- and mass-imbalanced Fermi mixtures.
These terms are related to damping processes of sound-like
(Anderson-Bogolyubov) collective modes and are relevant for the structure of
the complex pole of the pair fluctuation propagator. We derive conditions under
which damping occurs even at zero temperature for large enough mismatch of the
Fermi surfaces. We compare our analytical results with numerically computed
damping rates of the Anderson-Bogolyubov mode.",1908.08559v2
2019-11-05,On the Smallness Condition in Linear Inviscid Damping: Monotonicity and Resonance Chains,"We consider the linearized Euler equations around a smooth, bilipschitz shear
profile $U(y)$ on $\mathbb{T}_L \times \mathbb{R}$. We construct an explicit
flow which exhibits linear inviscid damping for $L$ sufficiently small, but for
which damping fails if $L$ is large. In particular, similar to the instability
results for convex profiles for a shear flow being bilipschitz is not
sufficient for linear inviscid damping to hold. Instead of an eigenvalue-based
argument the underlying mechanism here is shown to be based on a new cascade of
resonances moving to higher and higher frequencies in $y$, which is distinct
from the echo chain mechanism in the nonlinear problem.",1911.02066v1
2020-03-12,Optimal nonlinear damping control of second-order systems,"Novel nonlinear damping control is proposed for the second-order systems. The
proportional output feedback is combined with the damping term which is
quadratic to the output derivative and inverse to the set-point distance. The
global stability, passivity property, and convergence time and accuracy are
demonstrated. Also the control saturation case is explicitly analyzed. The
suggested nonlinear damping is denoted as optimal since requiring no design
additional parameters and ensuring a fast convergence, without transient
overshoots for a non-saturated and one transient overshoot for a saturated
control configuration.",2003.05670v3
2020-06-24,Stability of a star-shaped network with local Kelvin-Voigt damping and non-smooth coefficient at interface,"In this paper, we study the stability problem of a star-shaped network of
elastic strings with a local Kelvin-Voigt damping. Under the assumption that
the damping coefficients have some singularities near the transmission point,
we prove that the semigroup corresponding to the system is polynomially stable
and the decay rates depends on the speed of the degeneracy. This result
improves the decay rate of the semigroup associated to the system on an earlier
result of Z.~Liu and Q.~Zhang in \cite{LZ} involving the wave equation with
local Kelvin-Voigt damping and non-smooth coefficient at interface.",2006.14949v1
2020-11-06,A generalized finite element method for the strongly damped wave equation with rapidly varying data,"We propose a generalized finite element method for the strongly damped wave
equation with highly varying coefficients. The proposed method is based on the
localized orthogonal decomposition introduced and is designed to handle
independent variations in both the damping and the wave propagation speed
respectively. The method does so by automatically correcting for the damping in
the transient phase and for the propagation speed in the steady state phase.
Convergence of optimal order is proven in $L_2(H^1)$-norm, independent of the
derivatives of the coefficients. We present numerical examples that confirm the
theoretical findings.",2011.03311v1
2020-11-11,Reduction of back switching by large damping ferromagnetic material,"Recent studies on magnetization dynamics induced by spin-orbit torque have
revealed a weak dependence of the critical current for magnetization switching
on the damping constant of a ferromagnetic free layer. This study, however,
reveals that the damping constant nevertheless plays a key role in
magnetization switching induced by spin-orbit torque. An undesirable switching,
returning to an initial state, named as back switching, occurs in a ferromagnet
with an easy axis parallel to the current direction. Numerical and theoretical
analyses reveal that back switching is strongly suppressed when the damping
constant of the ferromagnet is large.",2011.05566v1
2021-02-28,Stability for an inverse source problem of the damped biharmonic plate equation,"This paper is concerned with the stability of the inverse source problem for
the damped biharmonic plate equation in three dimensions. The stability
estimate consists of the Lipschitz type data discrepancy and the high frequency
tail of the source function, where the latter decreases as the upper bound of
the frequency increases. The stability also shows exponential dependence on the
constant damping coefficient. The analysis employs Carleman estimates and time
decay estimates for the damped plate wave equation to obtain an exact
observability bound and depends on the study of the resonance-free region and
an upper bound of the resolvent of the biharmonic operator with respect to the
complex wavenumber.",2103.00461v1
2021-04-12,Lp-asymptotic stability of 1D damped wave equations with localized and linear damping,"In this paper, we study the $L^p$-asymptotic stability of the one-dimensional
linear damped wave equation with Dirichlet boundary conditions in $[0,1]$, with
$p\in (1,\infty)$. The damping term is assumed to be linear and localized to an
arbitrary open sub-interval of $[0,1]$. We prove that the semi-group
$(S_p(t))_{t\geq 0}$ associated with the previous equation is well-posed and
exponentially stable. The proof relies on the multiplier method and depends on
whether $p\geq 2$ or $1<p<2$.",2104.05679v1
2021-05-13,Sharp Polynomial Decay for Waves Damped from the Boundary in Cylindrical Waveguides,"We study the decay of global energy for the wave equation with H\""older
continuous damping placed on the $C^{1,1}$-boundary of compact and non-compact
waveguides with star-shaped cross-sections. We show there is sharp
$t^{-1/2}$-decay when the damping is uniformly bounded from below on the
cylindrical wall of product cylinders where the Geometric Control Condition is
violated. On non-product cylinders, we also show that there is $t^{-1/3}$-decay
when the damping is uniformly bounded from below on the cylindrical wall.",2105.06566v1
2021-06-02,Stabilisation of the generalised Rao-Nakra beam by partial viscous damping,"In this paper, we consider the stabilization of the generalized Rao-Nakra
beam equation, which consists of four wave equations for the longitudinal
displacements and the shear angle of the top and bottom layers and one
Euler-Bernoulli beam equation for the transversal displacement. Dissipative
mechanism are provided through viscous damping for two displacements. The
location of the viscous damping are divided into two groups, characterized by
whether both of the top and bottom layers are directly damped or otherwise.
Each group consists of three cases. We obtain the necessary and sufficient
conditions for the cases in group two to be strongly stable. Furthermore,
polynomial stability of certain orders are proved. The cases in group one are
left for future study",2106.01189v1
2021-09-01,Vibration damping platform for cavity quantum-electrodynamics experiments,"We present a mechanical platform with enhanced vibration damping properties
for cavity quantum-electrodynamics experiments. It is based on a composite
design that combines a soft, vibration-damping core with a rigid shell
maintaining optical alignment. It passively damps the vibrations generated by
piezoelectric actuators controlling the mirror positions. The mechanical
resonances of the platform, which lead to a length change of the cavity are
efficiently suppressed up to 100 kHz. Our platform is ultra-high vacuum
compatible and can be used in most applications, in particular where long
cavities and optical access to the cavity center are required.",2109.00439v1
2021-09-05,"Existence of a generalized polynomial attractor for the wave equation with nonlocal weak damping, anti-damping and critical nonlinearity","In this paper, we first establish a criterion based on contractive function
for the existence of polynomial attractors. This criterion only involves some
rather weak compactness associated with the repeated limit inferior and
requires no compactness, which makes it suitable for critical cases. Then by
this abstract theorem, we verify the existence of a polynomial attractor and
estimate its attractive speed for the wave equation with nonlocal weak damping,
anti-damping and critical nonlinearity.",2109.01967v2
2021-11-29,Stabilization of coupled wave equations with viscous damping on cylindrical and non-regular domains: Cases without the geometric control condition,"In this paper, we investigate the direct and indirect stability of locally
coupled wave equations with local viscous damping on cylindrical and
non-regular domains without any geometric control condition. If only one
equation is damped, we prove that the energy of our system decays polynomially
with the rate $t^{-\frac{1}{2}}$ if the two waves have the same speed of
propagation, and with rate $t^{-\frac{1}{3}}$ if the two waves do not propagate
at the same speed. Otherwise, in case of two damped equations, we prove a
polynomial energy decay rate of order $t^{-1}$.",2111.14554v1
2022-01-25,Linear pair creation damping of high frequency plasma oscillation,"We have studied the linear dispersion relation for Langmuir waves in plasmas
of very high density, based on the Dirac-Heisenberg-Wigner formalism. The
vacuum contribution to the physical observables leads to ultra-violet
divergences, that are removed by a charge renormalization. The remaining vacuum
contribution is small, and is in agreement with previously derived expressions
for the time-dependent vacuum polarization. The main new feature of the theory
is a damping mechanism similar to Landau damping, but where the plasmon energy
give rise to creation of electron-positron pairs. The dependence of the damping
rate (pair-creation rate) on wave-number, temperature, and density is analyzed.
Finally, the analytical results of linearized theory are compared.",2201.10370v1
2022-03-13,Continuum damping of topologically-protected edge modes at the boundary of a magnetized plasma,"Recent extension of the topological ideas to continuous systems with broken
time-reversal symmetry, such as magnetized plasmas, provides new insights into
the nature of scattering-free topologically-protected surface plasma waves
(TSPWs). We demonstrate a unique characteristic of TSPWs propagating above the
electron cyclotron frequency: their collisionless damping via coupling to the
continuum of resonant modes localized inside a smooth plasma-vacuum interface.
Damped TSPWs retain their unidirectional nature and robustness against
backscattering. When sheared magnetic field creates a boundary between damped
and undamped TSPWs, the two refract into each other without reflections",2203.06693v2
2022-04-21,On scattering and damping of Toroidal Alfven eigenmode by drift wave turbulence,"We demonstrate analytically that, in toroidal plasmas, scattering by drift
wave turbulence could lead to appreciable damping of toroidal Alfven eigenmodes
via generation of short-wavelength electron Landau damped kinetic Alfven waves.
A corresponding analytic expression of the damping rate is derived, and found
to be, typically, comparable to the linear drive by energetic particles. The
implications of this novel mechanism on the transport and heating processes in
burning plasmas are also discussed.",2204.09876v1
2022-10-30,Intrinsic polynomial squeezing for Balakrishnan-Taylor beam models,"We explore the energy decay properties related to a model in extensible beams
with the so-called energy damping. We investigate the influence of the
nonloncal damping coefficient in the stability of the model. We prove, for the
first time, that the corresponding energy functional is squeezed by
polynomial-like functions involving the power of the damping coefficient, which
arises intrinsically from the Balakrishnan-Taylor beam models. As a
consequence, it is shown that such models with nonlocal energy damping are
never exponentially stable in its essence.",2210.16931v1
2023-02-13,Damping of gravitational waves in f(R) gravity,"We study the damping of $f(R)$ gravitational waves by matter in flat
spacetime and in expanding universe. In the former case, we find that the
Landau damping of scalar mode in $f(R)$ theory exists, while that of the tensor
mode in general relativity does not; we also present the viscosity coefficients
and dispersion relations of the two modes. In the later case, we investigate
the evolution of tensor and scalar modes in Friedmann-Robertson-Walker (FRW)
cosmology with a matter distribution; by considering the case of $f(R)=R+\al
R^2$, we analysis the influence of parameter $\al$ on wave damping,and put
restrictions on its magnitude.",2302.06402v2
2023-07-11,Global smooth solution for the 3D generalized tropical climate model with partial viscosity and damping,"The three-dimensional generalized tropical climate model with partial
viscosity and damping is considered in this paper. Global well-posedness of
solutions of the three-dimensional generalized tropical climate model with
partial viscosity and damping is proved for $\alpha\geq\frac{3}{2}$ and
$\beta\geq4$. Global smooth solution of the three-dimensional generalized
tropical climate model with partial viscosity and damping is proved in
$H^s(\mathbb R^3)$ $(s>2)$ for $\alpha\geq\frac{3}{2}$ and $4\leq\beta\leq5$.",2307.05145v3
2023-08-07,Reconstruction of the initial data from the solutions of damped wave equations,"In this paper, we consider two types of damped wave equations: the weakly
damped equation and the strongly damped equation and show that the initial
velocity from the solution on the unit sphere. This inverse problem is related
to Photoacoustic Tomography (PAT), a hybrid medical imaging technique. PAT is
based on generating acoustic waves inside of an object of interest and one of
the mathematical problem in PAT is reconstructing the initial velocity from the
solution of the wave equation measured on the outside of object. Using the
spherical harmonics and spectral theorem, we demonstrate a way to recover the
initial velocity.",2308.03362v1
2023-09-26,Sharp conditions for exponential and non-exponential uniform stabilization of the time dependent damped wave equation,"It is classical that uniform stabilization of solutions to the damped wave
equation is equivalent to the geometric control condition The author previously
showed that, when the damping depends on time, a generalization of the
geometric control condition implies uniform stabilization at an exponential
rate. In this paper, it is shown that this generalization of the geometric
control condition is necessary for uniform stabilization at an exponential
rate. Furthermore, when the damping does not satisfy this generalization, and
has some additional structure, upper and lower bounds on non-exponential
uniform stabilization are computed. The qualitative behavior of these upper and
lower bounds coincide.",2309.15005v1
2023-10-19,The damped focusing cubic wave equation on a bounded domain,"For the focusing cubic wave equation on a compact Riemannian manifold of
dimension $3$, the dichotomy between global existence and blow-up for solutions
starting below the energy of the ground state is known since the work of Payne
and Sattinger. In the case of a damped equation, we prove that the dichotomy
between global existence and blow-up still holds. In particular, the damping
does not prevent blow-up. Assuming that the damping satisfies the geometric
control condition, we then prove that any global solution converges to a
stationary solution along a time sequence, and that global solutions below the
energy of the ground state can be stabilised, adapting the proof of a similar
result in the defocusing case.",2310.12644v2
2024-04-03,Damping Reveals Hidden Dimensions in Elastic Metastructures Through Induced Transparency,"Damping typically results in attenuation of vibrations and elastic wave
propagation in mechanical systems. Contrary to this conventional understanding,
we demonstrate experimentally and explain theoretically the revival of an
elastic wave transmitted through a periodic metastructure when a weak
non-Hermitian defect (damping mechanism) induces violation of time-reversal
symmetry. Damping alters the nature of the system's resonant modes, instigating
interference in the scattering field. This leads to transmission revival,
revealing the presence of hidden modes which are otherwise masked by the
symmetry. Our findings offer an innovative approach for designing
dissipation-driven switches and controllers and non-destructive structural
health monitoring systems.",2404.02979v1
1997-06-16,The terminal bulk Lorentz factor of relativistic electron-positron jet,"We present numerical simulation of bulk Lorentz factor of relativistic
electron positron jet driven by Compton rocket effect from accretion disk
radiation. The plasma is assumed to have a power-law energy distribution and is
continuously reheated to compensate for radiation losses. We include
Klein-Nishina (hereafter KN) corrections, and study the role of energy upper
cut-off, spectral index, and source compactness. We determine terminal bulk
Lorentz factor in the case of supermassive black holes relevant to AGN and
stellar black holes relevant to galactic microquasars. In the latter case,
effects of KN corrections are more important and induce terminal bulk Lorentz
factor smaller than in the former case. The result can explain the low bulk
Lorentz factors for galactic sources (GRS1915+105, GROJ1655-40) compared to
extragalactic ones. We also take into account the influence of the size of the
accretion disk; if the external radius is small enough, the bulk Lorentz factor
can be as high as 60, which is comparable to the values needed to explain
extragalactic gamma-ray bursts.",9706154v1
1998-04-17,The terminal bulk Lorentz factor of relativistic electron-positron jets,"We present numerical simulation of bulk Lorentz factor of relativistic
electron-positron jet driven by Compton rocket effect from accretion disc
radiation. The plasma is assumed to have a power-law distribution
$n_{e}(\gamma) \propto \gamma^{-s}$ whith $1 < \gamma< \gamma_{max}$ and is
continuously reheated to compensate for radiation losses. We include full
Klein-Nishina (hereafter KN) cross section, and study the role of energy upper
cut-off $\gamma_{max}$, spectral index $s$, and source compactness. We
determine terminal bulk Lorentz factor in the case of supermassive black holes
relevant to AGN and stellar black holes relevant to galactic microquasars. In
the latter case, Klein-Nishina cross section effect are more important, and
induce terminal bulk Lorentz factor smaller than in the former case. Our result
are in good agreement with bulk Lorentz factors observed in galactic sources
(GRS1915+105, GROJ1655-40) and extragalactic ones. Differences in scattered
radiation and acceleration mechanism efficiency in AGN environment can be
responsible for the variety of relativistic motion in those objects. We also
take into account the influence of the size of the accretion disc; if the
external radius is small enough, the bulk Lorentz factor can be as high as 60.",9804178v1
2005-09-09,"Lorentz-Lorenz Coefficient, Critical Point Constants, and Coexistence Curve of 1,1-Difluoroethylene","We report measurements of the Lorentz-Lorenz coefficient density dependence,
the critical temperature, and the critical density, of the fluid
1,1-difluoroethylene. Lorentz-Lorenz coefficient data were obtained by
measuring refractive index and density of the same fluid sample independently
of one another. Accurate determination of the Lorentz-Lorenz coefficient is
necessary for transformation of refractive index data into density data from
optics-based experiments on critical phenomena of fluid systems done with
different apparatus, with which independent measurement of the refractive indes
and density is not possible. Measurements were made along the coexistence curve
of the fluid and span the density range 0.01 to 0.80 g/cc. The Lorentz-Lorenz
coefficient results show a stronger density dependence along the coexistence
curve than previously observed in other fluids, with a monotonic decrease from
a density of about 0.2 g/cc onwards, and an overall variation of about 2.5% in
the density range studied. No anomaly in the Lorentz-Lorenz coefficient was
observed near the critical density. The critical temperature is measured at
Tc=(302.964+-0.002) K (29.814 C) and the measured critical density is
(0.4195+-0.0018)g/cc.",0509254v1
1997-11-19,Isometry groups and geodesic foliations of Lorentz manifolds. Part I: Foundations of Lorentz dynamics,"This is the first part of a series on non-compact groups acting isometrically
on compact Lorentz manifolds. This subject was recently investigated by many
authors. In the present part we investigate the dynamics of affine, and
especially Lorentz transformations. In particular we show how this is related
to geodesic foliations. The existence of geodesic foliations was (very
succinctly) mentioned for the first time by D'Ambra and Gromov, who suggested
that this may help in the classification of compact Lorentz manifolds with
non-compact isometry groups.
  In the Part II of the series, a partial classification of compact Lorentz
manifolds with non-compact isometry group will be achieved with the aid of
geometrical tools along with the dynamical ones presented here.",9711015v1
2004-03-12,Lorentz invariance and quantum gravity: an additional fine-tuning problem?,"Trying to combine standard quantum field theories with gravity leads to a
breakdown of the usual structure of space-time at around the Planck length,
1.6*10^{-35} m, with possible violations of Lorentz invariance. Calculations of
preferred-frame effects in quantum gravity have further motivated high
precision searches for Lorentz violation. Here, we explain that combining known
elementary particle interactions with a Planck-scale preferred frame gives rise
to Lorentz violation at the percent level, some 20 orders of magnitude higher
than earlier estimates, unless the bare parameters of the theory are
unnaturally strongly fine-tuned. Therefore an important task is not just the
improvement of the precision of searches for violations of Lorentz invariance,
but also the search for theoretical mechanisms for automatically preserving
Lorentz invariance.",0403053v4
2005-02-22,Testing Lorentz Invariance Violation in Quantum Gravity Theories,"Much research has been done in the latter years on the subject of Lorentz
violation induced by Quantum Gravity effects. On the theoretical side it has
been shown that both Loop Quantum Gravity and String Theory predict that
Lorentz violation can be induced at an energy near to the Planck scale. On the
other hand, most of the experimental results in the latter years, have
confirmed that the laws of physics are Lorentz invariant at low energy with
very high accuracy.
  The inclusion of one- and two-loop contributions from a Lorentz violating
Lagrangian dramatically change the above picture: the loop momenta run into the
Planck scale and above and from the ""divergent"" terms finite Lorentz violating
contributions of order one arise. These can be suppressed through suitable
counterterms in the Lagrangian, originating a strong fine tuning problem.
  A brief discussion of these issues and their possible influence in future
research follows.",0502093v1
2005-12-22,Modelling Planck-scale Lorentz violation via analogue models,"Astrophysical tests of Planck-suppressed Lorentz violations had been
extensively studied in recent years and very stringent constraints have been
obtained within the framework of effective field theory. There are however
still some unresolved theoretical issues, in particular regarding the so called
""naturalness problem"" - which arises when postulating that Planck-suppressed
Lorentz violations arise only from operators with mass dimension greater than
four in the Lagrangian. In the work presented here we shall try to address this
problem by looking at a condensed-matter analogue of the Lorentz violations
considered in quantum gravity phenomenology. Specifically, we investigate the
class of two-component BECs subject to laser-induced transitions between the
two components, and we show that this model is an example for Lorentz
invariance violation due to ultraviolet physics. We shall show that such a
model can be considered to be an explicit example high-energy Lorentz
violations where the ``naturalness problem'' does not arise.",0512127v1
1998-10-30,Lorentz Covariance and Internal Space-time Symmetry of Relativistic Extended Particles,"The difference between Lorentz invariance and Lorentz covariance is discussed
in detail. A covariant formalism is developed for the internal space-time
symmetry of extended particles, especially in connection with the insightful
observations Feynman made during the period 1969-72. A Lorentz-group formalism
is presented for the harmonic oscillator model of Feynman, Kislinger and
Ravndal, which was originally based on hadronic mass spectra. This covariant
version allows us to construct a parton distribution function by
Lorentz-boosting the oscillator wave function of a hadron at rest. The role of
the time-separation variable is discussed in detail. It is shown that, due to
our inability to make measurements on this variable, it belongs to Feynman's
rest of the universe. Our failure to observe the rest of the universe leads to
an increase in entropy.",9810538v1
2002-02-07,Redefining Spinors in Lorentz-Violating QED,"An analysis of spinor redefinitions in the context of the Lorentz-violating
QED extension is performed. Certain parameters that apparently violate Lorentz
invariance are found to be physically irrelevant as they can be removed from
the lagrangian using an appropriate redefinition of the spinor field
components. It is shown that conserved currents may be defined using a modified
action of the complex extension of the Lorentz group on the redefined spinors.
This implies a natural correspondence between the apparently Lorentz-violating
theory and conventional QED. Redefinitions involving derivatives are shown to
relate certain terms in the QED extension to lagrangians involving nonlocal
interactions or skewed coordinate systems. The redundant parameters in the QED
extension are identified and the lagrangian is rewritten in terms of physically
relevant coupling constants. The resulting lagrangian contains only physically
relevant parameters and transforms conventionally under Lorentz
transformations.",0202066v1
2003-09-02,Lorentz and CPT Violation in Neutrinos,"A general formalism is presented for violations of Lorentz and CPT symmetry
in the neutrino sector. The effective hamiltonian for neutrino propagation in
the presence of Lorentz and CPT violation is derived, and its properties are
studied. Possible definitive signals in existing and future
neutrino-oscillation experiments are discussed. Among the predictions are
direction-dependent effects, including neutrino-antineutrino mixing, sidereal
and annual variations, and compass asymmetries. Other consequences of Lorentz
and CPT violation involve unconventional energy dependences in oscillation
lengths and mixing angles. A variety of simple models both with and without
neutrino masses are developed to illustrate key physical effects. The
attainable sensitivities to coefficients for Lorentz violation in the
Standard-Model Extension are estimated for various types of experiments. Many
experiments have potential sensitivity to Planck-suppressed effects, comparable
to the best tests in other sectors. The lack of existing experimental
constraints, the wide range of available coefficient space, and the variety of
novel effects imply that some or perhaps even all of the existing data on
neutrino oscillations might be due to Lorentz and CPT violation.",0309025v1
2005-06-22,Lorentz invariant ensembles of vector backgrounds,"We consider gauge field theories in the presence of ensembles of vector
backgrounds. While Lorentz invariance is explicitely broken in the presence of
any single background, here, the Lorentz invariance of the theory is restored
by averaging over a Lorentz invariant ensemble of backgrounds, i.e. a set of
background vectors that is mapped onto itself under Lorentz transformations.
This framewkork is used to study the effects of a non-trivial but Lorentz
invariant vacuum structure or mass dimension two vector condensates by
identifying the background with a shift of the gauge field. Up to now, the
ensembles used in the literature comprise configurations corresponding to
non-zero field tensors together with such with vanishing field strength. We
find that even when constraining the ensembles to pure gauge configurations,
the usual high-energy degrees of freedom are removed from the spectrum of
asymptotic states in the presence of said backgrounds in euclidean and in
Minkowski space. We establish this result not only for the propagators to all
orders in the background and otherwise at tree level but for the full
propagator.",0506210v1
2000-04-01,Lorentz-Covariant Quantization of Massless Non-Abelian Gauge Fields in The Hamiltonian Path-Integral Formalism,"The Lorentz-covariant quantization performed in the Hamiltonian path-integral
formalism for massless non-Abelian gauge fields has been achieved. In this
quantization, the Lorentz condition, as a constraint, must be introduced
initially and incorporated into the Yang-Mills Lagrangian by the Lagrange
undetermined multiplier method. In this way, it is found that all Lorentz
components of a vector potential have thier corresponding conjugate canonical
variables. This fact allows us to define Lorentz-invariant poisson brackets and
carry out the quantization in a Lorent-covariant manner. Key words: Non-Abelian
gauge field, quantization, Hamiltonian path-integral formalism, Lorentz
covariance.",0004001v2
2001-07-27,Microcausality and Energy-Positivity in all frames imply Lorentz Invariance of dispersion laws,"A new presentation of the Borchers-Buchholz result of the Lorentz-invariance
of the energy-momentum spectrum in theories with broken Lorentz symmetry is
given in terms of properties of the Green's functions of microcausal Bose and
Fermi-fields. Strong constraints based on complex geometry phenomenons are
shown to result from the interplay of the basic principles of causality and
stability in Quantum Field Theory: if microcausality and energy-positivity in
all Lorentz frames are satisfied, then it is unavoidable that all stable
particles of the theory be governed by Lorentz-invariant dispersion laws: in
all the field sectors, discrete parts outside the continuum as well as the
thresholds of the continuous parts of the energy-momentum spectrum, with
possible holes inside it, are necessarily represented by mass-shell
hyperboloids (or the light-cone). No violation of this geometrical fact can be
produced by spontaneous breaking of the Lorentz symmetry.",0107240v1
2002-04-15,Microcausality and Energy-Positivity in all frames imply Lorentz Invariance of dispersion laws,"A new presentation of the Borchers-Buchholz result of the Lorentz-invariance
of the energy-momentum spectrum in theories with broken Lorentz symmetry is
given in terms of properties of the Green's functions of microcausal Bose and
Fermi-fields. Strong constraints based on complex geometry phenomenons are
shown to result from the interplay of the basic principles of causality and
stability in Quantum Field Theory: if microcausality and energy-positivity in
all Lorentz frames are satisfied, then it is unavoidable that all stable
particles of the theory be governed by Lorentz-invariant dispersion laws; in
all the field sectors, discrete parts outside the continuum as well as the
thresholds of the continuous parts of the energy-momentum spectrum, with
possible holes inside it, are necessarily represented by mass-shell
hyperboloids (or the light-cone). No violation of this geometrical fact can be
produced by spontaneous breaking of the Lorentz symmetry, even if the
field-theoretical framework is enlarged so as to include short-distance
singularities wilder than distributions.",0204118v1
2005-07-26,Lorentz Violation and Synchrotron Radiation,"We consider the radiation emitted by an ultrarelativistic charged particle
moving in a magnetic field, in the presence of an additional Lorentz-violating
interaction. In contrast with prior work, we treat a form of Lorentz violation
that is represented by a renormalizable operator. Neglecting the radiative
reaction force, the particle's trajectory can be determined exactly. The
resulting orbit is generally noncircular and does not lie in the place
perpendicular to the magnetic field. We do not consider any Lorentz violation
in the electromagnetic sector, so the radiation from the accelerated charge can
be determined by standard means, and the radiation spectrum will exhibit a
Lorentz-violating directional dependence. Using data on emission from the Crab
nebula, we can set a bound on a particular combination of Lorentz-violating
coefficients at the $6\times10^{-20}$ level.",0507258v2
2001-08-26,Clifford Algebras and Lorentz Group,"Finite-dimensional representations of the proper orthochronous Lorentz group
are studied in terms of spinor representations of the Clifford algebras. The
Clifford algebras are understood as an `algebraic covering' of a full system of
the finite-dimensional representations of the Lorentz group. Space-time
discrete symmetries P, T and PT, represented by fundamental automorphisms of
the Clifford algebras, are defined on all the representation spaces. Real,
complex, quaternionic and octonionic representations of the Lorentz group are
considered. Physical fields of the different types are formulated within such
representations. The Atiyah-Bott-Shapiro periodicity is defined on the Lorentz
group. It is shown that modulo 2 and modulo 8 periodicities of the Clifford
algebras allow to take a new look at the de Broglie-Jordan neutrino theory of
light and the Gell-Mann-Ne'emann eightfold way in particle physics. On the
representation spaces the charge conjugation C is represented by a
pseudoautomorphism of the complex Clifford algebra. Quotient representations of
the Lorentz group are introduced. It is shown that quotient representations are
the most suitable for description of the massless physical fields. By way of
example, neutrino field is described via the simplest quotient representation.
Weyl-Hestenes equations for neutrino field are given.",0108022v1
2005-10-13,Lorentz Beams,"A new kind of tridimensional scalar optical beams is introduced. These beams
are called Lorentz beams because the form of their transverse pattern in the
source plane is the product of two independent Lorentz functions. Closed-form
expression of free-space propagation under paraxial limit is derived and pseudo
non-diffracting features pointed out. Moreover, as the slowly varying part of
these fields fulfils the scalar paraxial wave equation, it follows that there
exist also Lorentz-Gauss beams, i.e. beams obtained by multipying the original
Lorentz beam to a Gaussian apodization function. Although the existence of
Lorentz-Gauss beams can be shown by using two different and independent ways
obtained recently from Kiselev [Opt. Spectr. 96, 4 (2004)] and Gutierrez-Vega
et al. [JOSA A 22, 289-298, (2005)], here we have followed a third different
approach, which makes use of Lie's group theory, and which possesses the merit
to put into evidence the symmetries present in paraxial Optics.",0510123v1
2005-10-25,Relativity from absoluteness,"The shortening of bodies in the direction of motion, Lorentz contraction,
follows from the solution of Maxwell's equations. Moving light clocks will tick
slower than those at rest because the speed of light does not depend on a
source of the light. The latter and Lorentz contraction imply the relativistic
time dilation. The invariance of the light speed defined as the round-trip
value follows from the time dilation and Lorentz contraction. An observer is
incognizant about his motion relative to the absolute frame of reference. So,
in order to synchronize spaced clocks in a moving reference frame he uses the
same procedure as in the absolute frame. We deduce the Lorentz transformation
from the Lorentz contraction, time dilation, invariance of the light speed and
synchronization procedure. Lorentz transformations constitute a symmetry group
of Maxwell's equations. That is the reason why the absolute frame can not be
distinguished among other inertial reference frames.",0510219v2
2006-08-25,Energy-Length Rule,"Lorentz ordering (causality) implies the following rule: for any given energy
p0 of a system there is a certain interval c0 on x0 so that their product is
the Lorentz ordering constant L It means p0c0 = L. The constant L=hc. Hence
Planck constant h in a similar way as c are both consequences of Lorentz
metric. The basic ideas are: 1. Lorentz metric implies that x0 must represent a
length like the other components of x in X 2. The dual metric space X* is well
defined since the Lorentz metric tensor is not singular. The components of the
vectors p in X*are interpreted as representing energy. The properties of the
physical systems that are direct consequences of the detailed structure of X
and X*, and so expressed through the Lorentz Limit L are presented.",0608253v1
2005-01-11,Symmetries of the Poincare sphere and decoherence matrices,"The Stokes parameters form a Minkowskian four-vector under various optical
transformations. As a consequence, the resulting two-by-two density matrix
constitutes a representation of the Lorentz group. The associated Poincare
sphere is a geometric representation of the Lorentz group. Since the Lorentz
group preserves the determinant of the density matrix, it cannot accommodate
the decoherence process through the decaying off-diagonal elements of the
density matrix, which yields to an incerese in the value of the determinant. It
is noted that the O(3,2) deSitter group contains two Lorentz subgroups. The
change in the determinant in one Lorentz group can be compensated by the other.
It is thus possible to describe the decoherence process as a symmetry
transformation in the O(3,2) space. It is shown also that these two coupled
Lorentz groups can serve as a concrete example of Feynman's rest of the
universe.",0501050v3
2007-10-18,Constrained Gauge Fields from Spontaneous Lorentz Violation,"Spontaneous Lorentz violation realized through a nonlinear vector field
constraint of the type $A_{\mu}A^{\mu}=M^{2}$ ($M$ is the proposed scale for
Lorentz violation) is shown to generate massless vector Goldstone bosons,
gauging the starting global internal symmetries in arbitrary relativistically
invariant theories. The gauge invariance appears in essence as a necessary
condition for these bosons not to be superfluously restricted in degrees of
freedom, apart from the constraint due to which the true vacuum in a theory is
chosen by the Lorentz violation. In the Abelian symmetry case the only possible
theory proves to be QED with a massless vector Goldstone boson naturally
associated with the photon, while the non-Abelian symmetry case results in a
conventional Yang-Mills theory. These theories, both Abelian and non-Abelian,
look essentially nonlinear and contain particular Lorentz (and $CPT$) violating
couplings when expressed in terms of the pure Goldstone vector modes. However,
they do not lead to physical Lorentz violation due to the simultaneously
generated gauge invariance.",0710.3479v2
2007-11-01,Lorentz Invariance Violation and Symmetry in Randers--Finsler Spaces,"Lorentz Invariance violation is a common feature of new physics beyond the
standard model. We show that the symmetry of Randers spaces deduces a modified
dispersion relation with characteristics of Lorentz Invariance violation. The
counterparts of the Lorentz transformation in the Einstein's Special Relativity
are presented explicitly. The coordinate transformations are unitary and form a
group. Generators and algebra satisfied by them are different from usual
Lorentz ones. The Randersian line element as well as speed of light is
invariant under the transformations. In particular, there is another invariant
speed which may be related with Planck scale and the mass of moving particle.
Thus, the Randers spaces is a suitable framework to discuss the Lorentz
Invariance violation.",0711.0056v2
2008-09-01,Relaxing Lorentz invariance in general perturbative anomalies,"We analyze the role of Lorentz symmetry in the perturbative non-gravitational
anomalies for a single family of fermions. The theory is assumed to be
translational invariant, power-counting renormalizable and based on a local
action, but is allowed to have general Lorentz violating operators. We study
the conservation of global and gauge currents associate with general internal
symmetry groups and find, by using a perturbative approach, that Lorentz
symmetry does not participate in the clash of symmetries that leads to the
anomalies. We first analyze the triangle graphs and prove that there are
regulators for which the anomalous part of the Ward identities exactly
reproduces the Lorentz invariant case. Then we show, by means of a regulator
independent argument, that the anomaly cancellation conditions derived in
Lorentz invariant theories remain necessary ingredients for anomaly freedom.",0809.0184v2
2008-09-27,Late-time acceleration and Phantom Divide Line Crossing with Non-minimal Coupling and Lorentz Invariance Violation,"We consider two alternative dark energy models: a Lorentz invariance
preserving model with a nonminimally coupled scalar field and a Lorentz
invariance violating model with a minimally coupled scalar field. We study
accelerated expansion and dynamics of equation of state parameter in these
scenarios. While a minimally coupled scalar field has not the capability to be
a successful dark energy candidate with cosmological constant line crossing, a
nonminimally coupled scalar field in the presence of Lorentz invariance or a
minimally coupled scalar field with Lorentz invariance violation have this
capability. In the later case, accelerated expansion and phantom divide line
crossing are the results of interactive nature of this Lorentz violating
scenario.",0809.4744v1
2010-01-28,Lorentz-violating effects on topological defects generated by two real scalar fields,"The influence of a Lorentz-violation on soliton solutions generated by a
system of two coupled scalar fields is investigated. Lorentz violation is
induced by a fixed tensor coefficient that couples the two fields. The
Bogomol'nyi method is applied and first-order differential equations are
obtained whose solutions minimize energy and are also solutions of the
equations of motion. The analysis of the solutions in phase space shows how the
stability is modified with the Lorentz violation. It is shown explicitly that
the solutions preserve linear stability despite the presence of Lorentz
violation. Considering Lorentz violation as a small perturbation, an analytical
method is employed to yield analytical solutions.",1001.5286v1
2010-04-29,Acoustic Black Holes from Abelian Higgs Model with Lorentz Symmetry Breaking,"In this paper we derive acoustic black hole metrics in the (3+1) and
(2+1)-dimensional Abelian Higgs model with Lorentz symmetry breaking. In this
set up the sound waves lose the Lorentz boost invariance and suffer a
'birefringence' effect. We have found acoustic black holes and respective
Hawking temperatures depending on the Lorentz violating parameter. Furthermore,
we obtain an acoustic Kerr-like black hole metric with the Lorentz violating
term affecting its rate of loss of mass. We also have shown that for suitable
values of the Lorentz violating parameter a wider spectrum of particle wave
function can be scattered with increased amplitude by the acoustic black hole.",1004.5360v3
2010-04-30,Effective Theory Approach to the Spontaneous Breakdown of Lorentz Invariance,"We generalize the coset construction of Callan, Coleman, Wess and Zumino to
theories in which the Lorentz group is spontaneously broken down to one of its
subgroups. This allows us to write down the most general low-energy effective
Lagrangian in which Lorentz invariance is non-linearly realized, and to explore
the consequences of broken Lorentz symmetry without having to make any
assumptions about the mechanism that triggers the breaking. We carry out the
construction both in flat space, in which the Lorentz group is a global
spacetime symmetry, and in a generally covariant theory, in which the Lorentz
group can be treated as a local internal symmetry. As an illustration of this
formalism, we construct the most general effective field theory in which the
rotation group remains unbroken, and show that the latter is just the
Einstein-aether theory.",1004.5596v1
2011-03-01,CPT Violation Does Not Lead to Violation of Lorentz Invariance and Vice Versa,"We present a class of interacting nonlocal quantum field theories, in which
the CPT invariance is violated while the Lorentz invariance is present. This
result rules out a previous claim in the literature that the CPT violation
implies the violation of Lorentz invariance. Furthermore, there exists the
reciprocal of this theorem, namely that the violation of Lorentz invariance
does not lead to the CPT violation, provided that the residual symmetry of
Lorentz invariance admits the proper representation theory for the particles.
The latter occurs in the case of quantum field theories on a noncommutative
space-time, which in place of the broken Lorentz symmetry possesses the twisted
Poincar\'e invariance. With such a CPT-violating interaction and the addition
of a C-violating (e.g., electroweak) interaction, the quantum corrections due
to the combined interactions could lead to different properties for the
particle and antiparticle, including their masses.",1103.0168v2
2012-03-19,Lorentz breaking Effective Field Theory and observational tests,"Analogue models of gravity have provided an experimentally realizable test
field for our ideas on quantum field theory in curved spacetimes but they have
also inspired the investigation of possible departures from exact Lorentz
invariance at microscopic scales. In this role they have joined, and sometime
anticipated, several quantum gravity models characterized by Lorentz breaking
phenomenology. A crucial difference between these speculations and other ones
associated to quantum gravity scenarios, is the possibility to carry out
observational and experimental tests which have nowadays led to a broad range
of constraints on departures from Lorentz invariance. We shall review here the
effective field theory approach to Lorentz breaking in the matter sector,
present the constraints provided by the available observations and finally
discuss the implications of the persisting uncertainty on the composition of
the ultra high energy cosmic rays for the constraints on the higher order,
analogue gravity inspired, Lorentz violations.",1203.4105v3
2012-08-06,Lorentz breaking effective field theory models for matter and gravity: theory and observational constraints,"A number of different approaches to quantum gravity are at least partly
phenomenologically characterized by their treatment of Lorentz symmetry, in
particular whether the symmetry is exact or modified/broken at the smallest
scales. For example, string theory generally preserves Lorentz symmetry while
analog gravity and Lifshitz models break it at microscopic scales. In models
with broken Lorentz symmetry there are a vast number of constraints on
departures from Lorentz invariance that can be established with low energy
experiments by employing the techniques of effective field theory in both the
matter and gravitational sectors. We shall review here the low energy effective
field theory approach to Lorentz breaking in these sectors and present various
constraints provided by available observations.",1208.1071v1
2014-01-28,Asymptotic states and renormalization in Lorentz-violating quantum field theory,"Asymptotic single-particle states in quantum field theories with small
departures from Lorentz symmetry are investigated perturbatively with focus on
potential phenomenological ramifications. To this end, one-loop radiative
corrections for a sample Lorentz-violating Lagrangian contained in the
Standard-Model Extension (SME) are studied at linear order in Lorentz
breakdown. It is found that the spinor kinetic operator, and thus the
free-particle physics, is modified by Lorentz-violating operators absent from
the original Lagrangian. As a consequence of this result, both the standard
renormalization procedure as well as the Lehmann-Symanzik-Zimmermann reduction
formalism need to be adapted. The necessary adaptations are worked out
explicitly at first order in Lorentz-breaking coefficients.",1401.7317v2
2015-09-20,Black hole entropy in the Chern-Simons-like theories of gravity and Lorentz-diffeomorphism Noether charge,"In the first order formalism of gravity theories, there are some theories
which are not Lorentz-diffeomorphism covariant. In the framework of such
theories we cannot apply the method of conserved charge calculation used in
Lorentz-diffeomorphism covariant theories. In this paper we firstly introduce
the total variation of a quantity due to an infinitesimal
Lorentz-diffeomorphism transformation. Secondly, in order to obtain the
conserved charges of Lorentz-diffeomorphism non-covariant theories, we extend
the Tachikawa method \cite{3}. This extension includes not only Lorentz gauge
transformation but also the diffeomorphism. We apply this method to the
Chern-Simons-like theories of gravity (CSLTG) and obtain a general formula for
the entropy of black holes in those theories. Finally, some examples on CSLTG
are provided and the entropy of the BTZ black hole is calculated in the context
of the examples.",1509.05972v2
2015-11-04,On existence of a possible Lorentz invariant modified gravity in Weitzenböck spacetime,"Modified gravity which was constructed by torsion scalar $T$, namely $f(T)$
doesn't respect Lorentz symmetry. As an attempt to make a new torsion based
modified gravity with Lorentz invarianve, recently $f(T,\mathcal{B})$
introduced where $B=2\nabla_{\mu}T^{\mu}$ \citep{Bahamonde:2015zma}. We would
argue, even when all is constructed and done in a self-consistent form, if you
handle them properly,we observe that there is no Lorentz invariant teleparallel
equivalent of $f(R)$ gravity. All we found is that the $f(R)$ gravity in which
$R$ must be computed in Weitzenb\""{o}ck spacetime, using Weitzenb\""{o}ck's
connection, nor Levi-Civita connections is the only possible Lorentz invariant
type of modified gravity. Consequently, $f(T)$ gravity can not obey Lorentz
symmetry not only in its orthodoxica form but even in this new framework
$f(T,\mathcal{B})$.",1511.01205v1
2016-03-20,Lorentz gauge and Coulomb gauge for tetrad field of gravity,"In general relativity, an inertial frame can only be established in a small
region of spacetime, and locally inertial frames are mathematically represented
by a tetrad field in gravity. The tetrad field is not unique due to the freedom
to perform Lorentz transformations in locally inertial frames, and there exists
freedom to choose the locally inertial frame at each spacetime point. The local
Lorentz transformations are known as non-Abelian gauge transformations for the
tetrad field, and to fix the gauge freedom, corresponding to the Lorentz gauge
$\partial^\mu\mathcal{A}_\mu=0$ and Coulomb gauge $\partial^i\mathcal{A}_i=0$
in electrodynamics, the Lorentz gauge and Coulomb gauge for the tetrad field
are proposed in the present work. Moreover, properties of the Lorentz gauge and
Coulomb gauge for tetrad field are discussed, which show the similarities to
those in electromagnetic field.",1603.07571v2
2016-06-28,Limits on Lorentz invariance violation at the Planck energy scale from H.E.S.S. spectral analysis of the blazar Mrk 501,"Some extensions to the Standard Model lead to the introduction of Lorentz
symmetry breaking terms, expected to induce deviations from Lorentz symmetry
around the Planck scale. A parameterization of effects due to Lorentz
invariance violation (LIV) can be introduced by adding an effective term to the
photon dispersion relation. This affects the kinematics of electron-positron
pair creation by TeV $\gamma$ rays on the extragalactic background light (EBL)
and translates into modifications of the standard EBL opacity for the TeV
photon spectra of extragalactic sources. Exclusion limits are presented,
obtained with the spectral analysis of H.E.S.S. observations taken on the
blazar Mrk 501 during the exceptional 2014 flare. The energy spectrum,
extending very significantly above 10 TeV, allows to place strong limits on LIV
in the photon sector at the level of the Planck energy scale for linear
perturbations in the photon dispersion relation, and provides the strongest
constraints presently for the case of quadratic perturbations.",1606.08600v2
2016-07-28,Test of Lorentz Violation with Astrophysical Neutrino Flavor,"The high-energy astrophysical neutrinos recently discovered by IceCube opened
a new way to test Lorentz and CPT violation through the astrophysical neutrino
mixing properties. The flavor ratio of astrophysical neutrinos is a very
powerful tool to investigate tiny effects caused by Lorentz and CPT violation.
There are 3 main findings; (1) current limits on Lorentz and CPT violation in
neutrino sector are not tight and they allow for any flavor ratios, (2)
however, the observable flavor ratio on the Earth is tied with the flavor ratio
at production, this means we can test both the presence of new physics and the
astrophysical neutrino production mechanism simultaneously, and (3) the
astrophysical neutrino flavor ratio is one of the most stringent tests of
Lorentz and CPT violation.",1607.08448v1
2013-08-27,Nuclear beta decay with Lorentz violation,"We consider the possibility of Lorentz-invariance violation in weak-decay
processes. We present a general approach that entails modifying the W-boson
propagator by adding a Lorentz-violating tensor to it. We describe the effects
of Lorentz violation on nuclear beta decay in this scenario. In particular we
show the expression for a first-forbidden transition with a spin change of two.
Using data from an old experiment on the rotational invariance of yttrium-90,
we derive several bounds on the Lorentz-violating parameters of the order of
10^(-6)-10^(-8).",1308.5829v2
2014-03-24,Estimating Flare-related Photospheric Lorentz Force Vector Changes within Active Regions,"It is shown that expressions for the global Lorentz force associated with a
flaring active region derived by Fisher {\it et al.} (2012) can be used to
estimate the Lorentz force changes for strong fields in large structures over
photospheric subdomains within active regions. Gary's~(2001) model for the
stratified solar atmosphere is used to demonstrate that in large-scale
structures with typical horizontal magnetic length scale $\gg 300$~km and with
strong magnetic fields ($\ge 1$~kG at the $\tau =1$ opacity layer at 5000~\AA),
the Lorentz force acting on the photosphere may be approximated by a surface
integral based on photospheric boundary data alone. These conditions cover many
of the sunspot fields and major neutral lines that have been studied using
Fisher {\it et al.}'s (2012) expressions over the past few years. The method
gives a reasonable estimate of flare-related Lorentz force changes based on
photospheric magnetogram observations provided that the Lorentz force changes
associated with the flare have a lasting effect on the observed fields, and are
not immediately erased by post-flare equilibration processes.",1403.6156v4
2016-12-31,Lorentz quantum mechanics,"We present a theoretical framework called Lorentz quantum mechanics, where
the dynamics of a system is a complex Lorentz transformation in complex
Minkowski space. In contrast, in usual quantum mechanics, the dynamics is the
unitary transformation in Hilbert space. In our Lorentz quantum mechanics,
there exist three types of states, space-like, light-like, and time-like.
Fundamental aspects are explored in parallel to the usual quantum mechanics,
such as matrix form of a Lorentz transformation, construction of Pauli-like
matrices for spinors. We also investigate the adiabatic evolution in this
mechanics, as well as the associated Berry curvature and Chern number. Three
typical physical systems, where this Lorentz quantum dynamics can arise, are
presented. They are one dimensional fermion gas, Bose-Einstein condensate (or
superfluid), and one dimensional antiferromagnet.",1701.00057v2
2017-01-16,Gluonic Lorentz violation and chiral perturbation theory,"By applying chiral-perturbation-theory methods to the QCD sector of the
Lorentz-violating Standard-Model Extension, we investigate Lorentz violation in
the strong interactions. In particular, we consider the CPT-even pure-gluon
operator of the minimal Standard-Model Extension. We construct the lowest-order
chiral effective Lagrangian for three as well as two light quark flavors. We
develop the power-counting rules and construct the heavy-baryon
chiral-perturbation-theory Lagrangian, which we use to calculate
Lorentz-violating contributions to the nucleon self energy. Using the
constructed effective operators, we derive the first stringent limits on many
of the components of the relevant Lorentz-violating parameter. We also obtain
the Lorentz-violating nucleon-nucleon potential. We suggest that this potential
may be used to obtain new limits from atomic-clock or deuteron storage-ring
experiments.",1701.04334v1
2017-04-13,Constraining the Mass Scale of a Lorentz-Violating Hamiltonian with the Measurement of Astrophysical Neutrino-Flavor Composition,"We study Lorentz violation effects on flavor transitions of high energy
astrophysical neutrinos. It is shown that the appearance of Lorentz violating
Hamiltonian can drastically change the flavor transition probabilities of
astrophysical neutrinos. Predictions of Lorentz violation effects on flavor
compositions of astrophysical neutrinos arriving on Earth are compared with
IceCube flavor composition measurement which analyzes astrophysical neutrino
events in the energy range between $25~{\rm TeV}$ and $2.8~{\rm PeV}$. Such a
comparison indicates that the future IceCube-Gen2 will be able to place
stringent constraints on Lorentz violating Hamiltonian in the neutrino sector.
We work out the expected sensitivities by IceCube-Gen2 on dimension-$3$ CPT-odd
and dimension-$4$ CPT-even operators in Lorentz violating Hamiltonian. The
expected sensitivities can improve on the current constraints obtained from
other types of experiments by more than two orders of magnitudes for certain
range of the parameter space.",1704.04027v3
2014-05-17,Attitude dynamics and control of spacecraft using geomagnetic Lorentz force,"The attitude stabilization of a charged rigid spacecraft in Low Earth Orbit
(LEO) using torques due to Lorentz force in pitch and roll directions is
considered. A spacecraft that generates an electrostatic charge on its surface
in the Earth magnetic field will be subject to perturbations from Lorentz
force. The Lorentz force acting on an electrostatically charged spacecraft may
provide a useful thrust for controlling a spacecraft's orientation. We assume
that the spacecraft is moving in the Earth's magnetic field in an elliptical
orbit under the effects of the gravitational, geomagnetic and Lorentz torques.
The magnetic field of the Earth is modeled as a non-tilted dipole. A model
incorporating all Lorentz torques as a function of orbital elements has been
developed on the basis of electric and magnetic fields. The stability of the
spacecraft orientation is investigated both analytically and numerically. The
existence and stability of equilibrium positions is investigated for different
values of the charge to mass ratio ($\alpha^*$). Stable orbits are identified
for various values of $\alpha^*$. The main parameters for stabilization of the
spacecraft are $\alpha^*$ and the difference between the components of the
moment of inertia of spacecraft.",1405.4411v1
2016-08-23,Hadronic Lorentz Violation in Chiral Perturbation Theory,"Any possible Lorentz violation in the hadron sector must be tied to Lorentz
violation at the underlying quark level. The relationships between the theories
at these two levels are studied using chiral perturbation theory. Starting from
a two-flavor quark theory that includes dimension-four Lorentz-violation
operators, the effective Lagrangians are derived for both pions and nucleons,
with novel terms appearing in both sectors. Since the Lorentz violation
coefficients for nucleons and pions are all related to a single set of
underlying quark coefficients, it is possible to place approximate bounds on
pion Lorentz violation using only proton and neutron observations. The
resulting bounds on four pion parameters are at the $10^{-23}$ level,
representing improvements of ten orders of magnitude.",1608.06503v1
2017-07-07,Limits on Lorentz violation in gravity from worldwide superconducting gravimeters,"We investigated Lorentz violation through anisotropy of gravity using a
worldwide array of 12 superconducting gravimeters. The Lorentz-violating signal
is extracted from the difference between measured gravity and a tidal model. At
the level of sensitivity we reach, ocean tides start to play an important role.
However, most models available that include ocean tides are empirically based
on measured gravity data, which may contain Lorentz-violating signal. In this
work we used an ocean tides included tidal model derived from first principles
to extract Lorentz-violating signal for the first time. We have bounded
space-space components of gravitational Lorentz violation in the minimal
standard model extension (SME) up to the order of $10^{-10}$, one order of
magnitude improved relative to previous atom-interferometer tests.",1707.02318v2
2018-01-18,"Lorentz Violation, Gravitoelectromagnetic Field and Bhabha Scattering","Lorentz symmetry is a fundamental symmetry in the Standard Model (SM) and in
General Relativity (GR). This symmetry holds true for all models at low
energies. However at energies near the Planck scale, it is conjectured that
there may be a very small violation of Lorentz symmetry. The Standard Model
Extension (SME) is a quantum field theory that includes a systematic
description of Lorentz symmetry violations in all sectors of particle physics
and gravity. In this paper SME is considered to study the physical process of
Bhabha Scattering in the Gravitoelectromagnetism (GEM) theory. GEM is an
important formalism that is valid in a suitable approximation of general
relativity. A new non-minimal coupling term that violates Lorentz symmetry is
used in this paper. Differential cross section for gravitational Bhabha
scattering is calculated. The Lorentz violation contributions to this GEM
scattering cross section are small and are similar in magnitude to the case of
the electromagnetic field.",1801.06000v1
2020-04-28,Kink-antikink collision in a Lorentz-violating $φ^4$ model,"In this work, kink-antikink collision in a two-dimensional Lorentz-violating
$\phi^4$ model is considered. It is shown that the Lorentz-violating term in
the proposed model does not affect the structure of the linear perturbation
spectrum of the standard $\phi^4$ model, and thus there exists only one
vibrational mode. The Lorentz-violating term impacts, however, the frequency
and spatial wave function of the vibrational mode. As a consequence, the
well-known results on $\phi^4$ kink-antikink collision will also change.
Collisions of kink-antikink pairs with different values of initial velocities
and Lorentz-violating parameters are simulated using the Fourier spectral
method. Our results indicate that models with larger Lorentz-violating
parameters would have smaller critical velocities $v_c$ and smaller widths of
bounce windows. Interesting fractal structures existing in the curves of
maximal energy densities of the scalar field are also found.",2004.13329v3
2012-05-27,"Variation of Mass with Velocity: ""Kugeltheorie"" or ""Relativtheorie""","This paper deals with four topics: The first subject is Abraham's spherical
electron, Lorentz's contracted electron and B\""ucherer's electron. The second
topic is Einstein's 1905 relativity theory of the motion of an electron.
Einstein obtained expressions for the longitudinal and transverse masses of the
electron using the principle of relativity and that of the constancy of the
velocity of light. The third topic is Einstein's reply to Ehrenfest's query.
Einstein's above solution appeared to Ehrenfest very similar to Lorentz's one:
a deformed electron. Einstein commented on Ehrenfest's paper and characterized
his work as a theory of principle and reasoned that beyond kinematics, the 1905
heuristic relativity principle could offer new connections between
non-kinematical concepts. The final topic is Kaufmann's experiments. Kaufmann
concluded that his measuring procedures were not compatible with the hypothesis
posited by Lorentz and Einstein. However, unlike Ehrenfest, he gave the first
clear account of the basic theoretical difference between Lorentz's and
Einstein's views. Finally, B\""ucherer conducted experiments that confirmed
Lorentz's and Einstein's models; Max Born analyzed the problem of a rigid body
and showed the existence of a limited class of rigid motions, and concluded,
""The main result was a confirmation of Lorentz's formula"".",1205.5951v1
2017-11-10,CPT and Lorentz violation en the Photon and $Z$-boson sector,"CPT and Lorentz violation in the photon sector is described within the
minimal Standard-Model Extension by a dimension-3 Chern-Simons-like operator
parametrized by a four-vector parameter $k_{AF}$ that has been very tightly
bounded by astrophysical observations. On the other hand, in the context of the
$SU(2)\times U(1)$ electroweak gauge sector of the Standard-Model Extension,
CPT and Lorentz violation is described similarly, by dimension-3 operators
parametrized by four-vector parameters $k_1$ and $k_2$. In this work, we
investigate in detail the effects of the resulting CPT and Lorentz violation in
the photon and $Z$-boson sectors upon electroweak-symmetry breaking. In
particular, we show that for the photon sector the relevant Lorentz-violating
effects are described at lowest order by the $k_{AF}$ term, but that there are
higher-order momentum-dependent effects due to photon-$Z$ boson mixing. As
bounds on CPT and Lorentz violation in the $Z$ sector are relatively weak,
these effects could be important phenomenologically. We investigate these
effects in detail in this work.",1711.03921v1
2018-03-21,"Lorentz violation, Gravitoelectromagnetism and Bhabha Scattering at finite temperature","Gravitoelectromagnetism (GEM) is an approach for the gravitation field that
is described using the formulation and terminology similar to that of
electromagnetism. The Lorentz violation is considered in the formulation of GEM
that is covariant in its form. In practice such a small violation of the
Lorentz symmetry may be expected in a unified theory at very high energy. In
this paper a non-minimal coupling term, which exhibits Lorentz violation, is
added as a new term in the covariant form. The differential cross section for
Bhabha scattering in the GEM framework at finite temperature is calculated that
includes Lorentz violation. The Thermo Field Dynamics (TFD) formalism is used
to calculate the total differential cross section at finite temperature. The
contribution due to Lorentz violation is isolated from the total cross section.
It is found to be small in magnitude.",1803.08016v1
2019-04-20,Field sources in a CPT-even Lorentz-violation Maxwell electrodynamics,"This paper is dedicated to the study of interactions between external sources
for the electromagnetic field in a model which exhibits Lorentz symmetry
breaking. We investigate such interactions in the CPT-even photon sector of the
Standard Model Extension (SME), where the Lorentz symmetry breaking is caused
by a background tensor $K_{(F)\alpha\beta\sigma\tau}$. Since the background
tensor is very tiny, we treat it perturbatively up to first order and we focus
on physical phenomena which have no counterpart in Maxwell electrodynamics. We
consider effects related to field sources describing point-like charges,
straight line currents and Dirac strings. We also investigate the so called
Aharonov-Bohm bound states in a Lorentz-symmetry breaking scenario. We use
atomic experimental data to verify if we could impose upper bounds to the
Lorentz-symmetry breaking parameters involved. We also use some overestimated
constrains for the Lorentz-symmetry breaking parameters in order to investigate
if the obtained results could be relevant for condensed matter systems.",1904.09389v1
2020-06-25,Lorentz--Karamata spaces,"In this paper, we consider Lorentz--Karamata spaces with slowly varying
functions and provide a comprehensive study of their properties.
  We consider Lorentz--Karamata functionals over an arbitrary sigma-finite
measure space equipped with a non-atomic measure and the corresponding
Lorentz--Karamata spaces. We characterise non-triviality of said spaces, then
study when they are equivalent to a Banach function space and obtain a complete
characterisation. We compute the fundamental function of said spaces and
describe the corresponding endpoint spaces. We further provide a complete
characterisation of when the Lorentz--Karamata spaces defined using
non-increasing rearrangement are equivalent to those defined using maximal
function. We provide a complete description of the associate spaces of
Lorentz--Karamata spaces. We also treat other topics like embeddings, absolute
continuity of the (quasi)norm, and Boyd indices.",2006.14455v4
2021-04-22,Probing low-energy Lorentz violation from high-energy modified dispersion in dipolar Bose-Einstein condensates,"We theoretically propose an experimentally viable scheme to use an impurity
atom in a dipolar Bose-Einstein condensate (BEC), in order to probe analogue
low-energy Lorentz violation from the modified dispersion at high energies as
suggested by quantum theories of gravity. We show that the density fluctuations
in the dipolar BEC possess a Lorentz-violating Bogoliubov spectrum
$\omega_\mathbf{k}=c_0|\mathbf{k}|f(c_0|\mathbf{k}|/M_\star)$, with recovery of
approximate Lorentz invariance (LI) at energy scales much below $M_\star$. When
$f$ is adjusted to dip below unity somewhere, the impurity, analogously dipole
coupled to the density fluctuations, experiences analogue drastic Lorentz
violation at arbitrarily low energies, reproducing the same responds of
Unruh-DeWitt detector to Lorentz-violating quantum fields. Being a
fundamentally quantum mechanical device, our quantum fluid platform provides an
experimentally realizable test field to verify whether the effective low energy
theory can reveal unexpected imprints of the theory's high energy structure, in
quantum field theory.",2104.11084v1
2021-05-27,Scalar Casimir effect for a conducting cylinder in a Lorentz violating background,"Following a field-theoretical approach, we study the scalar Casimir effect
upon a perfectly conducting cylindrical shell in the presence of spontaneous
Lorentz symmetry breaking. The scalar field is modeled by a Lorentz-breaking
extension of the theory for a real scalar quantum field in the bulk regions.
The corresponding Green's functions satisfying Dirichlet boundary conditions on
the cylindrical shell are derived explicitly. We express the Casimir pressure
(i.e. the vacuum expectation value of the normal-normal component of the
stress-energy tensor) as a suitable second-order differential operator acting
on the corresponding Green's functions at coincident arguments. The divergences
are regulated by making use of zeta function techniques, and our results are
successfully compared with the Lorentz invariant case. Numerical calculations
are carried out for the Casimir pressure as a function of the Lorentz-violating
coefficient, and an approximate analytical expression for the force is
presented as well. It turns out that the Casimir pressure strongly depends on
the Lorentz-violating coefficient and it tends to diminish the force.",2105.12953v1
2021-07-05,"Hadron wave functions in high-energy scattering, form factors and strong decays: the effects of the Lorentz contracted form","We study the class of processes where the dynamics depends essentially on the
properties of the hadron wave functions involved in the reactions. In this case
the momentum dependence of the form of wave functions imposed by Lorentz
invariance and in particular by the Lorentz contraction can be tested in the
experiment and may strongly influence the resulting cross sections. One example
of such observables is given by the hadron form factors, where it was shown
that the large Q behavior is mostly frozen, when the Lorentz contraction of the
hadron wave functions is taken into account. Another example considered
previously is the strong hadron decay with high energy emission. In this paper
we study the role of the Lorentz contraction in the high-energy hadron-hadron
scattering process at large momentum transfer. For the $pp$ and $p\bar p$
scattering at large $s$ it is shown that at small $-t << s$ the picture of two
exponential slopes in the differential cross section explained previously by
the author is stable while the backward scattering cross section is strongly
increased by the Lorentz contraction.",2107.01923v2
2021-08-09,Lorentz symmetry in ghost-free massive gravity,"The role of Lorentz symmetry in ghost-free massive gravity is studied,
emphasizing features emerging in approximately Minkowski spacetime. The static
extrema and saddle points of the potential are determined and their Lorentz
properties identified. Solutions preserving Lorentz invariance and ones
breaking four of the six Lorentz generators are constructed. Locally, globally,
and absolutely stable Lorentz-invariant extrema are found to exist for certain
parameter ranges of the potential. Gravitational waves in the linearized theory
are investigated. Deviations of the fiducial metric from the Minkowski metric
are shown to lead to pentarefringence of the five wave polarizations, which can
include superluminal modes and subluminal modes with negative energies in
certain observer frames. The Newton limit of ghost-free massive gravity is
explored. The propagator is constructed and used to obtain the gravitational
potential energy between two point masses. The result extends the Fierz-Pauli
limit to include corrections generically breaking both rotation and boost
invariance.",2108.04213v1
2022-04-28,Unruh-Fulling effect in nonlocal field theory: The role of Unruh decomposition,"We investigate the Unruh-Fulling effect in a class of nonlocal field theories
by examining both the number operator and Unruh-DeWitt detector methods. Unlike
in previous literature, we use Unruh quantization to quantize the matter field.
Such choice, as oppose to standard Minkowski decomposition, naturally
incorporates the time translational invariance in the positive frequency
Wightman function and thus captures the thermal equilibrium of the system. We
analyze the Unruh-Fulling effect for a massless real scalar field in both the
Lorentz noninvariant and Lorentz invariant nonlocal theories. In Lorentz
noninvariant nonlocal theory, the expectation value of number operator and the
response function of the detector are modified by an overall multiplicative
factor. Whereas in Lorentz invariant nonlocal theory these quantities remain
identical to those of the standard Unruh-Fulling effect. The temperature of the
thermal bath remains unaltered for both the Lorentz noninvariant and Lorentz
invariant nonlocal theories. Therefore, in terms of temperature, the nonlocal
Unruh-Fulling effect is universal while it is derived via Unruh quantization,
whereas the transition rate may be modified.",2204.13513v2
2022-08-24,Impact of Lorentz violation on anomalous magnetic moments of charged leptons,"We address the question whether a violation of Lorentz symmetry can explain
the tension between the measurement and the Standard-Model prediction of the
anomalous magnetic moment of the muon ($(g-2)_{\mu}$) and whether it can
significantly impact the one of the electron ($(g-2)_{e}$). While anisotropic
Lorentz-violating effects are, in general, expected to produce sidereal
oscillations in observables, isotropic Lorentz violation in the charged-lepton
sector could feed into $(g-2)_{e,\mu}$. However, we find that this type of
Lorentz violation, parametrised via a dim-4 field operator of the
Standard-Model Extension (SME), is already strongly constrained by the absence
of vacuum \v{C}erenkov radiation and photon decay. In particular, the
observations of very-high-energetic astrophysical photons at LHAASO and of
high-energetic electrons (muons) by the LHC (IceCube) place the most stringent
two-sided bounds on the relevant SME coefficients $\overset{\circ}{c}{}^{(e)}$
($\overset{\circ}{c}{}^{(\mu)}$). Therefore, any explanation of the tension in
$(g-2)_{\mu}$ via isotropic Lorentz violation of the minimal spin-degenerate
SME is excluded, and the possible size of its impact on $(g-2)_{e}$ is very
limited.",2208.11420v1
2022-09-01,Linear maps preserving the Lorentz spectrum of $3 \times 3$ matrices,"For a given $3 \times 3$ real matrix $A$, the eigenvalue complementarity
problem relative to the Lorentz cone consists of finding a real number
$\lambda$ and a nonzero vector $x \in \mathbb{R}^3$ such that $x^T(A-\lambda
I)x=0$ and both $x$ and $(A-\lambda I)x$ lie in the Lorentz cone, which is
comprised of all vectors in $\mathbb{R}^3$ forming a $45^\circ$ or smaller
angle with the positive $z$-axis. We refer to the set of all solutions
$\lambda$ to this eigenvalue complementarity problem as the Lorentz spectrum of
$A$. Our work concerns the characterization of the linear preservers of the
Lorentz spectrum on the space $M_3$ of $3 \times 3$ real matrices, that is, the
linear maps $\phi: M_3 \to M_3$ such that the Lorentz spectra of $A$ and
$\phi(A)$ are the same for all $A$. We have proven that all such linear
preservers take the form $\phi(A) = (Q \oplus [1])A(Q^T \oplus [1])$, where $Q$
is an orthogonal $2 \times 2$ matrix.",2209.00214v1
2022-12-15,Calculations in Lorentz-breaking scalar QED,"We purpose a study a Lorentz-breaking extension of the scalar QED. We
calculate the contributions in the Lorentz-violating parameters to the
two-point functions of scalar and gauge fields. We found that the two
background tensors, coming from the two sectors (scalar and gauge) are mixed in
the one-loop corrections. This shows that these two Lorentz-breaking terms
cannot be studied in an isolated form.",2212.09504v1
2023-04-25,Lorentz Violation in Finsler Geometry,"Lorentz invariance is one of the foundations of modern physics; however,
Lorentz violation may happen from the perspective of quantum gravity, and
plenty of studies on Lorentz violation have arisen in recent years. As a good
tool to explore Lorentz violation, Finsler geometry is a natural and
fundamental generalization of Riemann geometry. The Finsler structure depends
on both coordinates and velocities. Here, we simply introduce the mathematics
of Finsler geometry. We review the connection between modified dispersion
relations and Finsler geometries and discuss the physical influence from
Finsler geometry. We review the connection between Finsler geometries and
theories of Lorentz violation, such as the doubly special relativity, the
standard-model extension, and the very special relativity.",2304.12767v2
2023-05-21,Lorentz violation in $γ$-pair production ($e^{+}e^{-} \rightarrow γγ$),"This paper specifically focuses on the choice of a temporal background field
over a spatial one in the context of Lorentz symmetry breaking. By examining
the implications of this choice, we aim to understand the effects of Lorentz
violation in different scenarios, with an emphasis on the consequences of
adopting a purely temporal background field. In the analysis of $\gamma$-pair
production, a brief approach in QED is presented, exploring the production of a
pair of photons. Furthermore, the study investigates Lorentz violation with
vectorial nonminimal coupling, analyzing the modifications introduced by this
coupling in the scattering amplitude at the vertex. Additionally, Lorentz
violation with axial-like nonminimal coupling is explored, with a particular
focus. The additional coupling introduces further modifications to the
scattering amplitude, highlighting the intricate nature of Lorentz symmetry
breaking in different scenarios.",2305.12304v3
2023-11-18,PAIReD jet: A multi-pronged resonance tagging strategy across all Lorentz boosts,"We propose a new approach of jet-based event reconstruction that aims to
optimally exploit correlations between the products of a hadronic multi-pronged
decay across all Lorentz boost regimes. The new approach utilizes clustered
small-radius jets as seeds to define unconventional jets, referred to as PAIReD
jets. The constituents of these jets are subsequently used as inputs to machine
learning-based algorithms to identify the flavor content of the jet. We
demonstrate that this approach achieves higher efficiencies in the
reconstruction of signal events containing heavy-flavor jets compared to other
event reconstruction strategies at all Lorentz boost regimes. Classifiers
trained on PAIReD jets also have significantly better background rejections
compared to those based on traditional event reconstruction approaches using
small-radius jets at low Lorentz boost regimes. The combined effect of a higher
signal reconstruction efficiency and better classification performance results
in a two to four times stronger rejection of light-flavor jets compared to
conventional strategies at low Lorentz-boosts, and rejection rates similar to
classifiers based on large-radius multi-pronged jets at high Lorentz-boost
regimes.",2311.11011v1
2023-12-25,The hidden Lorentz Covariance of Quantum Mechanics,"This paper introduces a systematic algorithm for deriving a new unitary
representation of the Lorentz algebra ($so(1,3)$) and an irreducible unitary
representation of the extended (anti) de-Sitter algebra ($so(2,4)$) on
$\mathcal{L}^{2}(\mathcal{R}^{3},\frac{1}{r})$. This representation is
equivalent to a representation on $\mathcal{L}^{2}(\mathcal{R}^{3})$, and the
corresponding similarity transformation is identified. An explicit
representation in terms of differential operators is given, and it is shown
that the inner product is Lorentz invariant. Ensuring Lorentz covariance
demands a modification of the Heisenberg algebra, recognized as a phase space
algebra at the interface of gravitational and quantum realms (IGQR), which we
consider subordinate to Lorentz covariance. It is also demonstrated that time
evolution can be cast in a manifestly covariant form. Each mass sector of the
Hilbert space carries a representation of the Lorentz algebra, and the (anti)
de-Sitter algebra on each mass sector contracts to the Poincare algebra in the
flat configuration and momentum space limits. Finally, we show that
three-dimensional fuzzy space also carries a unitary representation of these
algebras, algebraically equivalent to the
$\mathcal{L}^{2}(\mathcal{R}^{3},\frac{1}{r})$ representation but not
necessarily equivalent as representations. Several outstanding issues are
identified for future exploration.",2312.15750v1
2024-01-06,Prospects for testing CPT and Lorentz symmetry with deuterium ground-state Zeeman-hyperfine transitions,"This work presents a model for testing Lorentz and CPT symmetry through
sidereal-variation studies of the hyperfine-Zeeman deuterium ground-state
transition frequencies. It represents an advancement over previous models by
using a well-established deuteron wave-function parametrization to calculate
contributions from nucleon Lorentz-violating operators toward the
Lorentz-violating frequency shift. Furthermore, this work extends the analysis
beyond the zeroth-boost order previously considered. This study centers on
deuterium's potential for testing Lorentz-violating nonminimal terms.
Specifically, it compares the prospects of an ongoing deuterium experiment with
the current best limits on nonminimal coefficients. The conclusion drawn is
that the deuterium experiment holds the potential to enhance and establish
first-time limits on nonminimal proton, neutron, and electron SME coefficients,
marking it as a valuable experiment in the current worldwide systematic search
for Lorentz and CPT violation.",2401.03272v1
2024-03-09,Power spectra and circular polarization of primordial gravitational waves with parity and Lorentz violations,"The violations of parity and Lorentz symmetries in gravity can change the
propagating properties of gravitational waves (GWs) in the cosmological
background, which can arise from a large number of parity- and
Lorentz-violating theories. In this paper, through a systematic parametrization
for characterizing possible derivations from the standard GW propagation in
general relativity, we study both the parity- and Lorentz-violating effects on
the power spectra and the polarization of the primordial gravitational waves
(PGWs) during the slow-roll inflation. To this end, we calculate explicitly the
power spectrum and the corresponding circular polarization of the PGWs
analytically by using the uniform asymptotic approximation. It is shown that
the new contributions to power spectra contain two parts, one from the
parity-violating terms and the other from the Lorentz-violating terms. While
the Lorentz-violating terms can only affect the overall amplitudes of PGWs, the
parity-violating terms induce nonzero circular polarization of PGWs, i.e., the
left-hand and right-hand polarization modes of GWs have different amplitudes.",2403.05841v1
1997-06-30,Damped Lyman Alpha Systems at High Redshift and Models of Protogalactic Disks,"We employ observationally determined intrinsic velocity widths and column
densities of damped Lyman-alpha systems at high redshift to investigate the
distribution of baryons in protogalaxies within the context of a standard cold
dark matter model. We proceed under the assumption that damped Lyman alpha
systems represent a population of cold, rotationally supported, protogalactic
disks and that the abundance of protogalactic halos is well approximated by a
cold dark matter model with critical density and vanishing cosmological
constant. Using conditional cross sections to observe a damped system with a
given velocity width and column density, we compare observationally inferred
velocity width and column density distributions to the corresponding
theoretically determined distributions for a variety of disk parameters and CDM
normalizations. In general, we find that the observations can not be reproduced
by the models for most disk parameters and CDM normalizations. Whereas the
column density distribution favors small disks with large neutral gas fraction,
the velocity width distribution favors large and thick disks with small neutral
gas fraction. The possible resolutions of this problem in the context of this
CDM model may be: (1) an increased contribution of rapidly rotating disks
within massive dark matter halos to damped Lyman-alpha absorption or (2) the
abandoning of simple disk models within this CDM model for damped Lyman-alpha
systems at high redshift. Here the first possibility may be achieved by
supposing that damped Lya system formation only occurs in halos with fairly
large circular velocities and the second possibility may result from a large
contribution of mergers and double-disks to damped Lya absorption at high
redshift.",9706290v1
2000-03-16,Non-existence of radiation damping of gravitational motions,"A rigorous, non-perturbative proof that there is no radiation damping of
gravitational motions.",0003230v1
2006-07-14,Lagrangian description of the radiation damping,"We present a Lagrangian formalism to the dissipative system of a charge
interacting with its own radiation field, which gives rise to the radiation
damping \cite{Heitler}, by the indirect representation doubling the phase-space
dimensions.",0607370v1
1994-05-17,Damping Rate of a Hard Photon in a Relativistic Plasma,"The damping rate of a hard photon in a hot relativistic QED and QCD plasma is
calculated using the resummation technique by Braaten and Pisarski.",9405309v1
1998-04-08,Evidence for xi- and t-dependent damping of the Pomeron Flux in the proton,"We show that a triple-Regge parametrization of inclusive single diffraction
agrees with the data in the following two domains: (a) xi > 0.03 at all t, (b)
|t| > 1 GeV^2 at all xi. Since the triple-Regge parametrization fails when
applied to the full xi-t range of the total single-diffractive cross section,
we conclude that damping occurs only at low-xi and low-|t|. We give a (``toy'')
parametrization of the damping factor, D(xi), valid at low-|t|, which describes
the diffractive differential cross-section (dsig/dt) data at the ISR and
roughly accounts for the observed s-dependence of diffractive total
cross-section up to Tevatron energies. However, an effective damping factor
calculated for the CDF fitted function for dsig/dxidt at sqrt(s} = 1800 GeV and
|t| = 0.05 GeV^2, suggests that, at fixed-xi, damping increases as s increases.
  We conjecture that, in the regions where the triple-Regge formalism describes
the data and there is no evidence of damping, factorization is valid and the
Pomeron-flux-factor may be universal. With the assumption that the observed
damping is due to multi-Pomeron exchange, our results imply that the recent UA8
demonstration that the effective Pomeron trajectory flattens for |t| > 1 GeV$^2
is evidence for the onset of the perturbative 2-gluon pomeron. Our damping
results may also shed some light on the self-consistency of recent measurements
of hard-diffractive jet production cross sections in the UA8, CDF and ZEUS
experiments.",9804257v1
2001-11-27,On the uniphase steady solutions of the nonlinear damped wave equation,"We study the steady uniphase and multiphase solutions of the discretized
nonlinear damped wave equation.Conditions for the stability abd instability of
the steady solutions are given;in the instability case the linear stable and
unstable associated manifolds are described.",0111281v1
2006-09-05,Damping estimates for oscillatory integral operators with finite type singularities,"We derive damping estimates and asymptotics of $L^p$ operator norms for
oscillatory integral operators with finite type singularities. The methods are
based on incorporating finite type conditions into $L^2$ almost orthogonality
technique of Cotlar-Stein.",0609145v1
2002-02-19,"On ""the authentic damping mechanism"" of the phonon damping model. II","This article continues a discussion raised in previous publications (LANL
preprint server, nucl-th/0202006 and nucl-th/0202020). I try to convince my
opponents that general arguments are not ""my case"" and may be applied to their
model.",0202058v1
1996-12-27,Coherent and trajectory-coherent states of a damped harmonic oscillator,"In this paper we construct the coherent and trajectory-coherent states of a
damped harmonic oscillator. We investigate the properties of this states.",9612051v2
2003-05-21,Probability representation of kinetic equation for open quantum system,"The tomographic probability distribution is used to decribe the kinetic
equations for open quantum systems. Damped oscillator is studied. Purity
parameter evolution for different damping regime is considered.",0305119v1
2007-08-09,The resonant damping of fast magnetohydrodynamic oscillations in a system of two coronal slabs,"Observations of transversal coronal loop oscillations very often show the
excitation and damping of oscillations in groups of coronal loops rather than
in individual and isolated structures. We present results on the oscillatory
properties (periods, damping rates, and spatial distribution of perturbations)
for resonantly damped oscillations in a system of two inhomogeneous coronal
slabs and compare them to the properties found in single slab loop models. A
system of two identical coronal loops is modeled, in Cartesian geometry, as
being composed by two density enhancements. The linear magnetohydrodynamic
(MHD) wave equations for oblique propagation of waves are solved and the
damping of the different solutions, due to the transversal inhomogeneity of the
density profile, is computed. The physics of the obtained results is analyzed
by an examination of the perturbed physical variables. We find that, due to the
interaction between the loops, the normal modes of oscillation present in a
single slab split into symmetric and antisymmetric oscillations when a system
of two identical slabs is considered. The frequencies of these solutions may
differ from the single slab results when the distance between the loops is of
the order of a few slab widths. Oblique propagation of waves weakens this
interaction, since solutions become more confined to the edges of the slabs.
The damping is strong for surface-like oscillations, while sausage body-like
solutions are unaffected. For some solutions, and small slab separations, the
damping in a system of two loops differs substantially from the damping of a
single loop.",0708.1251v1
2011-07-28,Creating quantum discord through local generalized amplitude damping,"We show that two qubits initially in completely classical state can create
quantum discord through a local generalized amplitude damping channel, but high
temperature will impede the creating of quantum discord.",1107.5670v1
2011-09-06,Damping of Alfven waves in solar partially ionized plasmas: effect of neutral helium in multi-fluid approach,"Chromospheric and prominence plasmas contain neutral atoms, which may change
the plasma dynamics through collision with ions. Most of the atoms are neutral
hydrogen, but a significant amount of neutral helium may also be present in the
plasma with a particular temperature. Damping of MHD waves due to ion collision
with neutral hydrogen is well studied, but the effects of neutral helium are
largely unknown. We aim to study the effect of neutral helium in the damping of
Alfven waves in solar partially ionized plasmas. We consider three-fluid
magnetohydrodynamic (MHD) approximation, where one component is
electron-proton-singly ionized helium and other two components are the neutral
hydrogen and neutral helium atoms. We derive the dispersion relation of linear
Alfven waves in isothermal and homogeneous plasma. Then we solve the dispersion
relation and derive the damping rates of Alfven waves for different plasma
parameters. The presence of neutral helium significantly enhances the damping
of Alfven waves compared to the damping due to neutral hydrogen at certain
values of plasma temperature (10000-40000 K) and ionization. Damping rates have
a peak near the ion-neutral collision frequency, but decrease for the higher
part of wave spectrum. Collision of ions with neutral helium atoms can be of
importance for the damping of Alfven waves in chromospheric spicules and in
prominence-corona transition regions.",1109.1154v1
2012-03-08,Damping rates of solar-like oscillations across the HR diagram. Theoretical calculations confronted to CoRoT and Kepler observations,"Space-borne missions CoRoT and {\it Kepler} are providing a rich harvest of
high-quality constraints on solar-like pulsators. Among the seismic parameters,
mode damping rates remains poorly understood and thus barely used to infer
physical properties of stars. Nevertheless, thanks to CoRoT and {\it Kepler}
space-crafts it is now possible to measure damping rates for hundreds of
main-sequence and thousands of red-giant stars with an unprecedented precision.
  By using a non-adiabatic pulsation code including a time-dependent convection
treatment, we compute damping rates for stellar models representative for
solar-like pulsators from the main-sequence to the red-giant phase. This allows
us to reproduce the observations of both CoRoT and {\it Kepler}, which
validates our modeling of mode damping rates and thus the underlying physical
mechanisms included in the modeling. Actually, by considering the perturbations
of turbulent pressure and entropy (including perturbation of the dissipation
rate of turbulent energy into heat) by the oscillation in our computation, we
succeed in reproducing the observed relation between damping rates and
effective temperature.
  Moreover, we discuss the physical reasons for mode damping rates to scale
with effective temperature, as observationally exhibited. Finally, this opens
the way for the use of mode damping rates to probe turbulent convection in
solar-like stars.",1203.1737v2
2012-09-14,Semi-linear structural damped waves,"We study the global existence of small data solutions for Cauchy problem for
the semi-linear structural damped wave equation with source term.",1209.3204v2
2012-10-25,Decay rates for the damped wave equation on the torus,"We address the decay rates of the energy for the damped wave equation when
the damping coefficient $b$ does not satisfy the Geometric Control Condition
(GCC). First, we give a link with the controllability of the associated
Schr\""odinger equation. We prove in an abstract setting that the observability
of the Schr\""odinger group implies that the semigroup associated to the damped
wave equation decays at rate $1/\sqrt{t}$ (which is a stronger rate than the
general logarithmic one predicted by the Lebeau Theorem).
  Second, we focus on the 2-dimensional torus. We prove that the best decay one
can expect is $1/t$, as soon as the damping region does not satisfy GCC.
Conversely, for smooth damping coefficients $b$, we show that the semigroup
decays at rate $1/t^{1-\eps}$, for all $\eps >0$. The proof relies on a second
microlocalization around trapped directions, and resolvent estimates.
  In the case where the damping coefficient is a characteristic function of a
strip (hence discontinuous), St\'{e}phane Nonnenmacher computes in an appendix
part of the spectrum of the associated damped wave operator, proving that the
semigroup cannot decay faster than $1/t^{2/3}$. In particular, our study shows
that the decay rate highly depends on the way $b$ vanishes.",1210.6879v1
2014-02-25,Asymptotic Profiles for wave equations with strong damping,"We consider the Cauchy problem in ${\bf R}^{n}$ for strongly damped wave
equations. We derive asymptotic profiles of these solutions with weighted
$L^{1,1}({\bf R}^{n})$ data by using a method introduced in [10].",1402.6073v1
2014-04-17,Exponential stability of the wave equation with memory and time delay,"We study the asymptotic behaviour of the wave equation with viscoelastic
damping in presence of a time-delayed damping. We prove exponential stability
if the amplitude of the time delay term is small enough.",1404.4456v1
2014-08-30,Marginalizing over the PageRank Damping Factor,"In this note, we show how to marginalize over the damping parameter of the
PageRank equation so as to obtain a parameter-free version known as TotalRank.
Our discussion is meant as a reference and intended to provide a guided tour
towards an interesting result that has applications in information retrieval
and classification.",1409.0104v1
2014-10-29,Blowup for the nonlinear Schrödinger equation with an inhomogeneous damping term in the $L^2$ critical case,"We consider the nonlinear Schr\""odinger equation with $L^2$-critical exponent
and an inhomogeneous damping term. By using the tools developed by Merle and
Raphael, we prove the existence of blowup phenomena in the energy space
$H^1(\mathbb{R})$.",1410.8011v1
2014-11-28,Landau damping,"Landau damping is calculated using real variables, clarifying the physical
mechanism.",1411.7793v1
2014-12-16,Linear Collisionless Landau Damping in Hilbert Space,"The equivalence between the Laplace transform [Landau L., J. Phys. USSR, 10
(1946), 25] and Hermite transform [Zocco and Schekochihin, Phys. Plasmas, 18,
102309 (2011)] solutions of the linear collisionless Landau damping problem is
proven.",1412.4913v1
2015-07-08,Calculation of continuum damping of Alfvén eigenmodes in 2D and 3D cases,"In ideal MHD, shear Alfv\'{e}n eigenmodes may experience dissipationless
damping due to resonant interaction with the shear Alfv\'{e}n continuum. This
continuum damping can make a significant contribution to the overall
growth/decay rate of shear Alfv\'{e}n eigenmodes, with consequent implications
for fast ion transport. One method for calculating continuum damping is to
solve the MHD eigenvalue problem over a suitable contour in the complex plane,
thereby satisfying the causality condition. Such an approach can be implemented
in three-dimensional ideal MHD codes which use the Galerkin method. Analytic
functions can be fitted to numerical data for equilibrium quantities in order
to determine the value of these quantities along the complex contour. This
approach requires less resolution than the established technique of calculating
damping as resistivity vanishes and is thus more computationally efficient. The
complex contour method has been applied to the three-dimensional finite element
ideal MHD code CKA . In this paper we discuss the application of the complex
contour technique to calculate the continuum damping of global modes in tokamak
as well as torsatron, W7X and H1-NF stellarator cases. To the authors'
knowledge these stellarator calculations represent the first calculation of
continuum damping for eigenmodes in fully three-dimensional equilibria. The
continuum damping of global modes in W7X and H1-NF stellarator configurations
investigated is found to depend sensitively on coupling to numerous poloidal
and toroidal harmonics.",1507.02072v1
2015-08-16,Jeans instability and hydrodynamic roots of Landau damping,"Landau damping of Langmuir waves is shown to have hydrodynamic roots, and, in
principle, might have been predicted (along with Langmuir waves) several
decades earlier, soon after Jeans (1902) paper appeared.",1508.03809v1
2016-09-24,Recovering the damping rates of cyclotron damped plasma waves from simulation data,"Plasma waves with frequencies close to the particular gyrofrequencies of the
charged particles in the plasma lose energy due to cyclotron damping. We
briefly discuss the gyro-resonance of low frequency plasma waves and ions
particularly with regard to particle-in-cell (PiC) simulations. A setup is
outlined which uses artificially excited waves in the damped regime of the wave
mode's dispersion relation to track the damping of the wave's electromagnetic
fields. Extracting the damping rate directly from the field data in real or
Fourier space is an intricate and non-trivial task. We therefore present a
simple method of obtaining the damping rate {\Gamma} from the simulation data.
This method is described in detail, focusing on a step-by-step explanation of
the course of actions. In a first application to a test simulation we find that
the damping rates obtained from this simulation generally are in good agreement
with theoretical predictions. We then compare the results of one-, two- and
three-dimensional simulation setups and simulations with different physical
parameter sets.",1609.07646v2
2016-10-25,Quadratically damped oscillators with non-linear restoring force,"In this paper we qualitatively analyse quadratically damped oscillators with
non-linear restoring force. In particular, we obtain Hamiltonian structure and
analytical form of the energy functions.",1610.07821v1
2017-08-25,On the entropy gain under the action of amplitude damping channel on qutrit,"After realising qutrit in the form of bipartite system we estimate from below
the entropy gain under the action of the amplitude damping channel.",1708.07710v1
2019-05-19,Finite time blow up for wave equations with strong damping in an exterior domain,"We consider the initial boundary value problem in exterior domain for
strongly damped wave equations with power type nonlinearity |u|^p. We will
establish blow-up results under some conditions on the initial data and the
exponent p.",1905.07782v1
2016-11-24,Longitudinal Stability Study for the FACET-II e+ Damping Ring,"This is an initial study of the longitudinal, single-bunch stability in the
proposed FACET-II e+ damping ring. It is preliminary because many vacuum
chamber objects of the ring have not yet been designed.",1611.08042v1
2009-12-08,Exact Invariant Solutions for Generalized Invicid Burgers' Equation with Damping,"In this work we study the Lie group analysis of a generalized invicid
Burgers' equations with damping. Seven inequivalent classes of this generalized
equation were classified and many exact and transformed solutions were obtained
for each class.",0912.1631v1
2015-12-07,"Damped and zero-damped quasinormal modes of charged, nearly extremal black holes","Despite recent progress, the complete understanding of the perturbations of
charged, rotating black holes as described by the Kerr-Newman metric remains an
open and fundamental problem in relativity. In this study, we explore the
existence of families of quasinormal modes of Kerr-Newman black holes whose
decay rates limit to zero at extremality, called zero-damped modes in past
studies. We review the nearly extremal and WKB approximation methods for
spin-weighted scalar fields (governed by the Dudley-Finley equation) and give
an accounting of the regimes where scalar zero-damped and damped modes exist.
Using Leaver's continued fraction method, we verify that these approximations
give accurate predictions for the frequencies in their regimes of validity. In
the nonrotating limit, we argue that gravito-electromagnetic perturbations of
nearly extremal Reissner-Nordstr\""{o}m black holes have zero-damped modes in
addition to the well-known spectrum of damped modes. We provide an analytic
formula for the frequencies of these modes, verify their existence using a
numerical search, and demonstrate the accuracy of our formula. These results,
along with recent numerical studies, point to the existence of a simple
universal equation for the frequencies of zero-damped gravito-electromagnetic
modes of Kerr-Newman black holes, whose precise form remains an open question.",1512.02247v2
2017-10-24,Demonstration of a switchable damping system to allow low-noise operation of high-Q low-mass suspension systems,"Low mass suspension systems with high-Q pendulum stages are used to enable
quantum radiation pressure noise limited experiments. Utilising multiple
pendulum stages with vertical blade springs and materials with high quality
factors provides attenuation of seismic and thermal noise, however damping of
these high-Q pendulum systems in multiple degrees of freedom is essential for
practical implementation. Viscous damping such as eddy-current damping can be
employed but introduces displacement noise from force noise due to thermal
fluctuations in the damping system. In this paper we demonstrate a passive
damping system with adjustable damping strength as a solution for this problem
that can be used for low mass suspension systems without adding additional
displacement noise in science mode. We show a reduction of the damping factor
by a factor of 8 on a test suspension and provide a general optimisation for
this system.",1710.08698v2
2018-10-04,Damping of slow surface sausage modes in photospheric waveguides,"There has been considerable interest in sausage modes in photospheric
waveguides like pores and sunspots, and slow surface sausage modes (SSSMs) have
been suggested to damp ufficiently rapidly to account for chromospheric
heating. Working in the framework of linear resistive magnetohydrodynamics, we
examine how efficient electric resistivity and resonant absorption in the cusp
continuum can be for damping SSSMs in a photospheric waveguide with equilibrium
parameters compatible with recent measurements of a photospheric pore. For
SSSMs with the measured wavelength, we find that the damping rate due to the
cusp resonance is substantially less strong than theoretically expected with
the thin-boundary approximation. The damping-time-to-period ratio ($\tau/P$) we
derive for standing modes, equivalent to the damping-length-to-wavelength ratio
for propagating modes given the extremely weak dispersion, can reach only $\sim
180$. However, the accepted values for electric resistivity ($\eta$) correspond
to a regime where both the cusp resonance and resistivity play a role. The
values for $\tau/P$ attained at the largest allowed $\eta$ may reach $\sim 30$.
We conclude that electric resistivity can be considerably more efficient than
the cusp resonance for damping SSSMs in the pore in question, and it needs to
be incorporated into future studies on the damping of SSSMs in photospheric
waveguides in general.",1810.02051v1
2018-10-20,Landau Damping in a weakly collisional regime,"In this paper, we consider the nonlinear Vlasov-Poisson equations in a weakly
collisional regime and study the linear Boltzmann collision operator. We prove
that Landau damping still occurs in this case.",1810.10955v1
2018-10-26,Energy regenerative damping in variable impedance actuators for long-term robotic deployment,"Energy efficiency is a crucial issue towards longterm deployment of compliant
robots in the real world. In the context of variable impedance actuators
(VIAs), one of the main focuses has been on improving energy efficiency through
reduction of energy consumption. However, the harvesting of dissipated energy
in such systems remains under-explored. This study proposes a novel variable
damping module design enabling energy regeneration in VIAs by exploiting the
regenerative braking effect of DC motors. The proposed damping module uses four
switches to combine regenerative and dynamic braking, in a hybrid approach that
enables energy regeneration without a reduction in the range of damping
achievable. A physical implementation on a simple VIA mechanism is presented in
which the regenerative properties of the proposed module are characterised and
compared against theoretical predictions. To investigate the role of variable
regenerative damping in terms of energy efficiency of longterm operation,
experiments are reported in which the VIA equipped with the proposed damping
module performs sequential reaching to a series of stochastic targets. The
results indicate that the combination of variable stiffness and variable
regenerative damping is preferable to achieve the optimal trade-off between
task performance and energy efficiency. Use of the latter results in a 25%
performance improvement on overall performance metrics (incorporating reaching
accuracy, settling time, energy consumption and regeneration), over comparable
schemes where either stiffness or damping are fixed.",1810.11246v3
2017-11-30,Asymptotic for a second order evolution equation with vanishing damping term and Tikhonov regularization,"We investigate the asymptotic behavior of solutions to a second order
differential equation with vanishing damping term, convex potential and
regularizing Tikhonov term.",1711.11241v1
2018-12-26,A class large solution of the 2D MHD equations with velocity and magnetic damping,"In this paper, we construct a class global large solution to the
two-dimensional MHD equations with damp terms in the nonhomogeneous Sobolev
framework.",1812.10310v2
2019-01-24,Generalization of Stokes-Einstein relation to coordinate dependent damping and diffusivity: An apparent conflict,"Brownian motion with coordinate dependent damping and diffusivity is
ubiquitous. Understanding equilibrium of a Brownian particle with coordinate
dependent diffusion and damping is a contentious area. In this paper, we
present an alternative approach based on already established methods to this
problem. We solve for the equilibrium distribution of the over-damped dynamics
using Kramers-Moyal expansion. We compare this with the over-damped limit of
the generalized Maxwell-Boltzmann distribution. We show that the equipartition
of energy helps recover the Stokes-Einstein relation at constant diffusivity
and damping of the homogeneous space. However, we also show that, there exists
no homogeneous limit of coordinate dependent diffusivity and damping with
respect to the applicability of Stokes-Einstein relation when it does not hold
locally. In the other scenario where the Stokes-Einstein relation holds
locally, one needs to impose a restriction on the local maximum velocity of the
Brownian particle to make the modified Maxwell-Boltzmann distribution coincide
with the modified Boltzmann distribution in the over-damped limit.",1901.08358v4
2019-02-19,Linear inviscid damping near monotone shear flows,"We give an elementary proof of sharp decay rates and the linear inviscid
damping near monotone shear flow in a periodic channel, first obtained in [14].
We shall also obtain the precise asymptotics of the solutions, measured in the
space $L^{\infty}$.",1902.06849v1
2019-04-18,Damping of Propagating Kink Waves in the Solar Corona,"Alfv\'enic waves have gained renewed interest since the existence of
ubiquitous propagating kink waves were discovered in the corona. {It has long
been suggested that Alfv\'enic} waves play an important role in coronal heating
and the acceleration of the solar wind. To this effect, it is imperative to
understand the mechanisms that enable their energy to be transferred to the
plasma. Mode conversion via resonant absorption is believed to be one of the
main mechanisms for kink wave damping, and is considered to play a key role in
the process of energy transfer. This study examines the damping of propagating
kink waves in quiescent coronal loops using the Coronal Multi-channel
Polarimeter (CoMP). A coherence-based method is used to track the Doppler
velocity signal of the waves, enabling us to investigate the spatial evolution
of velocity perturbations. The power ratio of outward to inward propagating
waves is used to estimate the associated damping lengths and quality factors.
To enable accurate estimates of these quantities, {we provide the first
derivation of a likelihood function suitable for fitting models to the ratio of
two power spectra obtained from discrete Fourier transforms. Maximum likelihood
estimation is used to fit an exponential damping model to the observed
variation in power ratio as a function of frequency.} We confirm earlier
indications that propagating kink waves are undergoing frequency dependent
damping. Additionally, we find that the rate of damping decreases, or
equivalently the damping length increases, for longer coronal loops that reach
higher in the corona.",1904.08834v1
2019-12-15,A result for nonexistence of global solutions to semi-linear structural damped wave model,"Main goal of this note is to give a result for nonexistence of global
solutions and determine the critical exponent as well to a semi-linear
structurally damped wave equation.",1912.07066v1
2020-09-23,Remark on the exponential decay of the solutions of the damped wave equation,"A condition which guaranties the exponential decay of the solutions of the
initial-boundary value problem for the damped wave equation is proved. A method
for the effective computability of the coefficient of exponential decay is also
presented.",2009.11244v1
2020-10-13,The Impact of Damping in Second-Order Dynamical Systems with Applications to Power Grid Stability,"We consider a broad class of second-order dynamical systems and study the
impact of damping as a system parameter on the stability, hyperbolicity, and
bifurcation in such systems. We prove a monotonic effect of damping on the
hyperbolicity of the equilibrium points of the corresponding first-order
system. This provides a rigorous formulation and theoretical justification for
the intuitive notion that damping increases stability. To establish this
result, we prove a matrix perturbation result for complex symmetric matrices
with positive semidefinite perturbations to their imaginary parts, which may be
of independent interest. Furthermore, we establish necessary and sufficient
conditions for the breakdown of hyperbolicity of the first-order system under
damping variations in terms of observability of a pair of matrices relating
damping, inertia, and Jacobian matrices, and propose sufficient conditions for
Hopf bifurcation resulting from such hyperbolicity breakdown. The developed
theory has significant applications in the stability of electric power systems,
which are one of the most complex and important engineering systems. In
particular, we characterize the impact of damping on the hyperbolicity of the
swing equation model which is the fundamental dynamical model of power systems,
and demonstrate Hopf bifurcations resulting from damping variations.",2010.06662v2
2020-10-26,Linear Predictive Coding for Acute Stress Prediction from Computer Mouse Movements,"Prior work demonstrated the potential of using the Linear Predictive Coding
(LPC) filter to approximate muscle stiffness and damping from computer mouse
movements to predict acute stress levels of users. Theoretically, muscle
stiffness and damping in the arm can be estimated using a mass-spring-damper
(MSD) biomechanical model. However, the damping frequency (i.e., stiffness) and
damping ratio values derived using LPC were not yet compared with those from a
theoretical MSD model. This work demonstrates that the damping frequency and
damping ratio from LPC are significantly correlated with those from an MSD
model, thus confirming the validity of using LPC to infer muscle stiffness and
damping. We also compare the stress level binary classification performance
using the values from LPC and MSD with each other and with neural network-based
baselines. We found comparable performance across all conditions demonstrating
LPC and MSD model-based stress prediction efficacy, especially for longer mouse
trajectories. Clinical relevance: This work demonstrates the validity of the
LPC filter to approximate muscle stiffness and damping and predict acute stress
from computer mouse movements.",2010.13836v3
2020-11-01,Sharp dimension estimates of the attractor of the damped 2D Euler-Bardina equations,"We prove existence of the global attractor of the damped and driven 2D
Euler--Bardina equations on the torus and give an explicit two-sided estimate
of its dimension that is sharp as $\alpha\to0^+$.",2011.00607v1
2021-03-30,Strong solution of 3D-NSE with exponential damping,"In this paper we prove the existence and uniqueness of strong solution of the
incompressible Navier-Stokes equations with damping $\alpha
(e^{\beta|u|^2}-1)u$.",2103.16707v1
2021-06-22,Choice of Damping Coefficient in Langevin Dynamics,"This article considers the application of Langevin dynamics to sampling and
investigates how to choose the damping parameter in Langevin dynamics for the
purpose of maximizing thoroughness of sampling. Also, it considers the
computation of measures of sampling thoroughness.",2106.11597v1
2021-09-27,Damping transition in an open generalized Aubry-André-Harper model,"We study the damping dynamics of the single-particle correlation for an open
system under periodic and aperiodic order, which is dominated by the Lindblad
master equation. In the absence of the aperiodic order, the Liouvillian
superoperator exhibits the non-Hermitian skin effect, which leads to
unidirectional damping dynamics, dubbed as ""chiral damping"". Due to the
non-Hermitian skin effect, the damping dynamics is boundary sensitive: The
long-time damping of such open systems is algebraic under periodic boundary
conditions but exponential under open boundary conditions. We reveal the phase
transition with the inclusion of the hopping amplitude modulation. By using the
spectral topology and a finite-size scaling analysis in the commensurate case,
we show there exists a phase transition of the skin effect with non-Bloch
anti-parity-time symmetry breaking. For the incommensurate case, we find richer
phases with the coexistence of the non-Hermitian skin effect and the Anderson
localization, which are separated by a generalized mobility edge. We reveal the
transition of the damping dynamics as a consequence of the phase transition.
Furthermore, we propose a possible scheme with ultracold atoms in a dissipative
momentum lattice to realize and detect the damping dynamics.",2109.12958v2
2022-01-20,Long Time Decay of Leray Solution of 3D-NSE With Exponential Damping,"We study the uniqueness, the continuity in $L^2$ and the large time decay for
the Leray solutions of the $3D$ incompressible Navier-Stokes equations with
nonlinear exponential damping term $a (e^{b |u|^{\bf 4}}-1)u$, ($a,b>0$).",2201.08292v1
2023-03-20,Nonlinear Damping and Field-aligned Flows of Propagating Shear Alfvén Waves with Braginskii Viscosity,"Braginskii MHD provides a more accurate description of many plasma
environments than classical MHD since it actively treats the stress tensor
using a closure derived from physical principles. Stress tensor effects
nonetheless remain relatively unexplored for solar MHD phenomena, especially in
nonlinear regimes. This paper analytically examines nonlinear damping and
longitudinal flows of propagating shear Alfv\'en waves. Most previous studies
of MHD waves in Braginskii MHD considered the strict linear limit of vanishing
wave perturbations. We show that those former linear results only apply to
Alfv\'en wave amplitudes in the corona that are so small as to be of little
interest, typically a wave energy less than $10^{-11}$ times the energy of the
background magnetic field. For observed wave amplitudes, the Braginskii viscous
dissipation of coronal Alfv\'en waves is nonlinear and a factor around $10^9$
stronger than predicted by the linear theory. Furthermore, the dominant damping
occurs through the parallel viscosity coefficient $\eta_0$, rather than the
perpendicular viscosity coefficient $\eta_2$ in the linearized solution. This
paper develops the nonlinear theory, showing that the wave energy density
decays with an envelope $(1+z/L_d)^{-1}$. The damping length $L_d$ exhibits an
optimal damping solution, beyond which greater viscosity leads to lower
dissipation as the viscous forces self-organise the longitudinal flow to
suppress damping. Although the nonlinear damping greatly exceeds the linear
damping, it remains negligible for many coronal applications.",2303.11128v1
2023-09-04,Joint Oscillation Damping and Inertia Provision Service for Converter-Interfaced Generation,"As renewable generation becomes more prevalent, traditional power systems
dominated by synchronous generators are transitioning to systems dominated by
converter-interfaced generation. These devices, with their weaker damping
capabilities and lower inertia, compromise the system's ability to withstand
disturbances, pose a threat to system stability, and lead to oscillations and
poor frequency response performance. While some new converter-interfaced
generations are capable of providing superior damping and fast frequency
control, there is a lack of effective measures to incentivize manufacturers to
adopt them. To address this gap, this paper defines the joint oscillation
damping and inertia provision services at the system level, seeking to
encourage converter-interfaced generation to provide enhanced damping and fast
frequency response capabilities. Our approach is anchored in a novel convex
parametric formulation that combines oscillation mode and frequency stability
constraints. These constraints ensure a sufficient damping ratio for all
oscillation modes and maintain transient frequency trajectories within
acceptable limits. They are designed to integrate smoothly into various
operational and planning optimization frameworks. Using this formulation, we
introduce a joint service for oscillation damping and inertia provision based
on a cost-minimization problem. This facilitates the optimal allocation of
damping and virtual inertia to converters, achieving both small-signal
stability and frequency stability. Furthermore, we investigate the economic
effects of introducing this service into a new ancillary service market,
assessing its impact on system operations and cost-efficiency. Numerical tests
highlight the service's efficacy in ensuring both small-signal stability and
frequency stability, and offer insights into potential economic benefits.",2309.01321v1
2024-01-09,Damping Separation of Finite Open Systems in Gravity-Related Experiments in the Free Molecular Flow Regime,"The residual gas damping of the test mass (TM) in the free molecular flow
regime is studied in the finite open systems for high-precision gravity-related
experiments. Through strict derivation, we separate the damping coefficients
for two finite open systems, i.e., the bi-plate system and the sensor core
system, into base damping and diffusion damping. This elucidates the
relationship between the free damping in the infinite gas volume and the
proximity damping in the constrained volume, unifies them into one microscopic
picture, and allows us to point out three pathways of energy dissipation in the
bi-plate gap. We also provide the conditions that need to be met to achieve
this separation. In applications, for space gravitational wave detection, our
results for the residual gas damping coefficient for the 4TM torsion balance
experiment is the closest one to the experimental and simulation data compared
to previous models. For the LISA mission, our estimation for residual gas
acceleration noise at the sensitive axis is consistent with the simulation
result, within about $5\%$ difference. In addition, in the test of the
gravitational inverse-square law, our results suggest that the constraint on
the distance between TM and the conducting membrane can be reduced by about
$28\%$.",2401.04808v1
2024-01-30,The Velocity-Space Signature of Transit-Time Damping,"Transit-time damping (TTD) is a process in which the magnetic mirror force --
induced by the parallel gradient of magnetic field strength -- interacts with
resonant plasma particles, leading to the collisionless damping of
electromagnetic waves and the resulting energization of those particles through
the perpendicular component of the electric field, $E_\perp$. In this study, we
utilize the recently developed field-particle correlation technique to analyze
gyrokinetic simulation data. This method enables the identification of the
velocity-space structure of the TTD energy transfer rate between waves and
particles during the damping of plasma turbulence. Our analysis reveals a
unique bipolar pattern of energy transfer in velocity space characteristic of
TTD. By identifying this pattern, we provide clear evidence of TTD's
significant role in the damping of strong plasma turbulence. Additionally, we
compare the TTD signature with that of Landau damping (LD). Although they both
produce a bipolar pattern of phase-space energy density loss and gain about the
parallel resonant velocity of the \Alfvenic waves, they are mediated by
different forces and exhibit different behaviors as $v_\perp \to 0$. We also
explore how the dominant damping mechanism varies with ion plasma beta
$\beta_i$, showing that TTD dominates over LD for $\beta_i > 1$. This work
deepens our understanding of the role of TTD in the damping of weakly
collisional plasma turbulence and paves the way to seek the signature of TTD
using in situ spacecraft observations of turbulence in space plasmas.",2401.16697v1
2024-03-04,How long will the quasar UV/optical flickering be damped?,"The UV/optical light curves of Active Galactic Nuclei (AGNs) are commonly
described by the Damped Random Walk (DRW) model. However, the physical
interpretation of the damping timescale, a key parameter in the DRW model,
remains unclear. Particularly, recent observations indicate a weak dependence
of the damping timescale upon both wavelength and accretion rate, clearly being
inconsistent with the accretion-disk theory. In this study, we investigate the
damping timescale in the framework of the Corona Heated Accretion disk
Reprocessing (CHAR) model, a physical model that describes AGN variability. We
find that while the CHAR model can reproduce the observed power spectral
densities of the 20-year light curves for 190 sources from \cite{Stone2022},
the observed damping timescale, as well as its weak dependence on wavelength,
can also be well recovered through fitting the mock light curves with DRW. We
further demonstrate that such weak dependence is artificial due to the effect
of inadequate durations of light curves, which leads to best-fitting damping
timescales lower than the intrinsic ones. After eliminating this effect, the
CHAR model indeed yields a strong dependence of the intrinsic damping timescale
on the bolometric luminosity and rest-frame wavelength. Our results highlight
the demand for sufficiently long light curves in AGN variability studies and
important applications of the CHAR model in such studies.",2403.01691v1
2024-04-08,On the Stability of swelling porous elastic soils with a single internal fractional damping,"We study polynomial stability to the one-dimensional system in the linear
isothermal theory of swelling porous elastic soils with an internal fractional
damping. We establish an optimal decay result by frequency domain method",2404.05577v1
2005-04-18,Chemical Abundances in SFG and DLA,"We investigate the chemical abundances of local star-forming galaxies which
cause Damped Lyman Alpha lines. A metallicity versus redshift diagram is
constructed, on which the chemical abundances of low-redshift star-forming
galaxy populations are compared with those of high-redshift Damped Lyman Alpha
systems. We disucss two types of experiments on individual star-forming
galaxies. In the first, the Damped Lyman Alpha line is created against an
internal ultraviolet light source generated by a star-forming cluster or a
supernova explosion. In the second, the Damped Lyman Alpha line is seen against
a background Quasar. The metallicities measured from ionized gas in the
star-forming regions, and neutral gas in the Damped Lyman Alpha systems, are
compared with one another on a case-by-case basis. We highlight the occurrence
of the star-forming galaxy/Quasar pair SBS 1543+593/HS 1543+5921, where the
emission- and absorption-line derived abundances give the same result. We argue
that we therefore can in principle, interpret Damped Lyman Alpha system
metallicities as an extension of star-forming galaxy metallicities to higher
redshifts, supporting that gas-rich galaxies had lower chemical abundances when
the were younger.",0504389v2
1995-09-06,Fermi Liquid Damping and NMR Relaxation in Superconductors,"Electron collisions for a two dimensional Fermi liquid (FL) are shown to give
a quasiparticle damping with interesting frequency and temperature variations
in the BCS superconducting state. The spin susceptibility which determines the
structure of the damping is analyzed in the normal state for a Hubbard model
with a constant on--site Coulomb repulsion. This is then generalized to the
superconducting state by including coherence factors and self energy and vertex
corrections. Calculations of the NMR relaxation rate reveal that the FL damping
structure can reduce the Hebel--Slichter peak, in agreement with data on the
organic superconductor (MDT-TTF)$_2$AuI$_2$. However, the strongly suppressed
FL damping in the superconducting state does not eliminate the Hebel-Slichter
peak, and thus suggests that other mechanisms are needed to explain the NMR
data on (TMTSF)$_2$ClO$_4$, the BEDT organic compounds, and cuprate
superconductors. Predictions of the temperature variation of the damping and
the spin response are given over a wide frequency range as a guide to
experimental probes of the symmetry of the superconducting pairs.",9509028v1
1997-05-08,Topological asymmetry in the damping-pairing contribution of electron-boson scattering,"We make a harmonic analysis of the pairing and damping contribution of a
finite $k$ range isotropic electron-phonon (or other boson) scattering in an
anisotropic two-dimensional electronic system. We show that the pairing
contribution of the anisotropic part of the electronic system can be much
larger than its damping contribution enhancing significantly T_c. The higher is
the order of the harmonic of the electronic anisotropy, smaller is its damping
contribution and higher can be the asymmetry in its damping-pairing
contribution. This could explain the puzzle of a much broader quasiparticle
peak in the n-doped than in the p-doped cuprates, their smaller T_c's being
also attributed to larger damping effects.",9705071v1
2000-03-29,Damping of condensate collective modes due to equilibration with the non-condensate,"We consider the damping of condensate collective modes at finite temperatures
arising from lack of equilibrium between the condensate and the non-condensate
atoms, an effect that is ignored in the usual discussion of the collisionless
region. As a first approximation, we ignore the dynamics of the thermal cloud.
Our calculations should be applicable to collective modes of the condensate
which are oscillating out-of-phase with the thermal cloud. We obtain a
generalized Stringari equation of motion for the condensate at finite
temperatures, which includes a damping term associated with the fact that the
condensate is not in diffusive equilibrium with the static thermal cloud. This
inter-component collisional damping of the condensate modes is comparable in
magnitude to the Landau damping considered in the recent literature.",0003481v5
2006-06-27,Theoretical limit of the minimal magnetization switching field and the optimal field pulse for Stoner particles,"The theoretical limit of the minimal magnetization switching field and the
optimal field pulse design for uniaxial Stoner particles are investigated. Two
results are obtained. One is the existence of a theoretical limit of the
smallest magnetic field out of all possible designs. It is shown that the limit
is proportional to the damping constant in the weak damping regime and
approaches the Stoner-Wohlfarth (SW) limit at large damping. For a realistic
damping constant, this limit is more than ten times smaller than that of
so-called precessional magnetization reversal under a non-collinear static
field. The other is on the optimal field pulse design: If the magnitude of a
magnetic field does not change, but its direction can vary during a reversal
process, there is an optimal design that gives the shortest switching time. The
switching time depends on the field magnitude, damping constant, and magnetic
anisotropy. However, the optimal pulse shape depends only on the damping
constant.",0606681v1
2007-02-01,Adiabatic Domain Wall Motion and Landau-Lifshitz Damping,"Recent theory and measurements of the velocity of current-driven domain walls
in magnetic nanowires have re-opened the unresolved question of whether
Landau-Lifshitz damping or Gilbert damping provides the more natural
description of dissipative magnetization dynamics. In this paper, we argue that
(as in the past) experiment cannot distinguish the two, but that
Landau-Lifshitz damping nevertheless provides the most physically sensible
interpretation of the equation of motion. From this perspective, (i) adiabatic
spin-transfer torque dominates the dynamics with small corrections from
non-adiabatic effects; (ii) the damping always decreases the magnetic free
energy, and (iii) microscopic calculations of damping become consistent with
general statistical and thermodynamic considerations.",0702020v3
2001-02-09,Magnetic effects on the viscous boundary layer damping of the r-modes in neutron stars,"This paper explores the effects that magnetic fields have on the viscous
boundary layers (VBLs) that can form in neutron stars at the crust-core
interface, and it investigates the VBL damping of the gravitational-radiation
driven r-mode instability. Approximate solutions to the magnetohydrodynamic
equations valid in the VBL are found for ordinary-fluid neutron stars. It is
shown that magnetic fields above 10^9 Gauss significantly change the structure
of the VBL, and that magnetic fields decrease the VBL damping time.
Furthermore, VBL damping completely suppresses the r-mode instability for B >=
10^{12} Gauss. Thus, magnetic fields will profoundly affect the VBL damping of
the r-mode instability in hot young pulsars (that are cool enough to have
formed a solid crust). One can speculate that magnetic fields can affect the
VBL damping of this instability in LMXBs and other cold old pulsars (if they
have sufficiently large internal fields).",0102042v1
2002-07-26,Landau damping of partially incoherent Langmuir waves,"It is shown that partial incoherence, in the form of stochastic phase noise,
of a Langmuir wave in an unmagnetized plasma gives rise to a Landau-type
damping. Starting from the Zakharov equations, which describe the nonlinear
interaction between Langmuir and ion-acoustic waves, a kinetic equation is
derived for the plasmons by introducing the Wigner-Moyal transform of the
complex Langmuir wave field. This equation is then used to analyze the
stability properties of small perturbations on a stationary solution consisting
of a constant amplitude wave with stochastic phase noise. The concomitant
dispersion relation exhibits the phenomenon of Landau-like damping. However,
this damping differs from the classical Landau damping in which a Langmuir
wave, interacting with the plasma electrons, loses energy. In the present
process, the damping is non-dissipative and is caused by the resonant
interaction between an instantaneously-produced disturbance, due to the
parametric interactions, and a partially incoherent Langmuir wave, which can be
considered as a quasi-particle composed of an ensemble of partially incoherent
plasmons.",0207050v1
2003-01-30,Dynamic effects of electromagnetic wave on a damped two-level atom,"We studied the dynamic effects of an electromagnetic(EM) wave with circular
polarization on a two-level damped atom. The results demonstrate interesting ac
Stark split of energy levels of damped atom. The split levels have different
energies and lifetimes, both of which depend on the interaction and the damping
rate of atom. When the frequency of the EM wave is tuned to satisfy the
resonance condition in the strong coupling limit, the transition probability
exhibits Rabi oscillation. Momentum transfer between atom and EM wave shows
similar properties as the transition probability under resonance condition. For
a damped atom interacting with EM field, there exists no longer stable state.
More importantly, if the angular frequency of the EM wave is tuned the same as
the atomic transition frequency and its amplitude is adjusted appropriately
according to the damping coefficients, we can prepare a particular 'Dressed
State' of the coupled system between atom and EM field and can keep the system
coherently in this 'Dressed state' for a very long time. This opens another way
to prepare coherent atomic states.",0301166v1
2007-12-18,"Spectroscopy of electronic defect states in Cu(In, Ga)(S, Se)$_2$-based heterojunctions and Schottky diodes under damp-heat exposure","The changes of defect characteristics induced by accelerated lifetime tests
on the heterostructure n-ZnO/i-ZnO/CdS/Cu(In, Ga)(S, Se)$_2$/Mo relevant for
photovoltaic energy conversion are investigated. We subject heterojunction and
Schottky devices to extended damp heat exposure at 85$^{\circ}$C ambient
temperature and 85% relative humidity for various time periods. In order to
understand the origin of the pronounced changes of the devices, we apply
current--voltage and capacitance--voltage measurements, admittance
spectroscopy, and deep-level transient spectroscopy. The fill factor and
open-circuit voltage of test devices are reduced after prolonged damp heat
treatment, leading to a reduced energy conversion efficiency. We observe the
presence of defect states in the vicinity of the CdS/chalcopyrite interface.
Their activation energy increases due to damp heat exposure, indicating a
reduced band bending at the Cu(In, Ga)(S, Se)$_2$ surface. The Fermi-level
pinning at the buffer/chalcopyrite interface, maintaining a high band bending
in as-grown cells, is lifted due to the damp-heat exposure. We also observe
changes in the bulk defect spectra due to the damp-heat treatment.",0712.2982v1
2008-05-07,Comparison Between Damping Coefficients of Measured Perforated Micromechanical Test Structures and Compact Models,"Measured damping coefficients of six different perforated micromechanical
test structures are compared with damping coefficients given by published
compact models. The motion of the perforated plates is almost translational,
the surface shape is rectangular, and the perforation is uniform validating the
assumptions made for compact models. In the structures, the perforation ratio
varies from 24% - 59%. The study of the structure shows that the
compressibility and inertia do not contribute to the damping at the frequencies
used (130kHz - 220kHz). The damping coefficients given by all four compact
models underestimate the measured damping coefficient by approximately 20%. The
reasons for this underestimation are discussed by studying the various flow
components in the models.",0805.0893v1
2009-01-26,Dispersion of Waves in Relativistic Plasmas with Isotropic Particle Distributions,"The dispersion laws of Langmuir and transverse waves are calculated in the
relativistic non-magnetized formalism for several isotropic particle
distributions: thermal, power-law, relativistic Lorentzian $\kappa,$ and hybrid
$\beta$. For Langmuir waves the parameters of superluminal undamped, subluminal
damped principal and higher modes are determined for a range of distribution
parameters. The undamped and principal damped modes are found to match
smoothly. Principal damped and second damped modes are found not to match
smoothly. The presence of maximum wavenumber is discovered above that no
longitudinal modes formally exist. The higher damped modes are discovered to be
qualitatively different for thermal and certain non-thermal distributions.
Consistently with the known results, the Landau damping is calculated to be
stronger for non-thermal power-law-like distributions. The dispersion law is
obtained for the single undamped transverse mode. The analytic results for the
simplest distributions are provided.",0901.4050v1
2009-03-28,Torsional waves propagation in an initially stressed dissipative cylinder,"The present paper has been framed to show the effect of damping on the
propagation of torsional waves in an initially stressed, dissipative,
incompressible cylinder of infinite length. A governing equation has been
formulated on Biot's incremental deformation theory. The velocities of
torsional waves are obtained as complex ones, in which real part gives the
phase velocity of propagation and corresponding imaginary part gives the
damping. The study reveals that the damping of the medium has strong effect in
the propagation of torsional wave. Since every medium has damping so it is more
realistic to use the damped wave equation instead of the undamped wave
equation. The study also shows that the velocity of propagation of such waves
depend on the presence of initial stress. The influences of damping and initial
stresses are shown separately.",0903.4896v1
2009-04-09,Evaluating the locality of intrinsic precession damping in transition metals,"The Landau-Lifshitz-Gilbert damping parameter is typically assumed to be a
local quantity, independent of magnetic configuration. To test the validity of
this assumption we calculate the precession damping rate of small amplitude
non-uniform mode magnons in iron, cobalt, and nickel. At scattering rates
expected near and above room temperature, little change in the damping rate is
found as the magnon wavelength is decreased from infinity to a length shorter
than features probed in recent experiments. This result indicates that
non-local effects due to the presence of weakly non-uniform modes, expected in
real devices, should not appreciably affect the dynamic response of the element
at typical operating temperatures. Conversely, at scattering rates expected in
very pure samples around cryogenic temperatures, non-local effects result in an
order of magnitude decrease in damping rates for magnons with wavelengths
commensurate with domain wall widths. While this low temperature result is
likely of little practical importance, it provides an experimentally testable
prediction of the non-local contribution of the spin-orbit torque-correlation
model of precession damping. None of these results exhibit strong dependence on
the magnon propagation direction.",0904.1455v1
2009-04-29,Atomistic theory for the damping of vibrational modes in mono-atomic gold chains,"We develop a computational method for evaluating the damping of vibrational
modes in mono-atomic metallic chains suspended between bulk crystals under
external strain. The damping is due to the coupling between the chain and
contact modes and the phonons in the bulk substrates. The geometry of the atoms
forming the contact is taken into account. The dynamical matrix is computed
with density functional theory in the atomic chain and the contacts using
finite atomic displacements, while an empirical method is employed for the bulk
substrate. As a specific example, we present results for the experimentally
realized case of gold chains in two different crystallographic directions. The
range of the computed damping rates confirm the estimates obtained by fits to
experimental data [Frederiksen et al., Phys. Rev. B, 75, 205413(R)(2007)]. Our
method indicates that an order-of-magnitude variation in the damping is
possible even for relatively small changes in the strain. Such detailed insight
is necessary for a quantitative analysis of damping in metallic atomic chains,
and in explaining the rich phenomenology seen in the experiments.",0904.4627v2
2010-07-27,Alfvèn wave phase-mixing and damping in the ion cyclotron range of frequencies,"Aims. To determine the effect of the Hall term in the generalised Ohm's law
on the damping and phase mixing of Alfven waves in the ion cyclotron range of
frequencies in uniform and non-uniform equilibrium plasmas. Methods. Wave
damping in a uniform plasma is treated analytically, whilst a Lagrangian remap
code (Lare2d) is used to study Hall effects on damping and phase mixing in the
presence of an equilibrium density gradient. Results. The magnetic energy
associated with an initially Gaussian field perturbation in a uniform resistive
plasma is shown to decay algebraically at a rate that is unaffected by the Hall
term to leading order in k^2di^2 where k is wavenumber and di is ion skin
depth. A similar algebraic decay law applies to whistler perturbations in the
limit k^2di^2>>1. In a non-uniform plasma it is found that the
spatially-integrated damping rate due to phase mixing is lower in Hall MHD than
it is in MHD, but the reduction in the damping rate, which can be attributed to
the effects of wave dispersion, tends to zero in both the weak and strong phase
mixing limits.",1007.4752v2
2011-02-24,Environment-assisted quantum Minority games,"The effect of entanglement and correlated noise in a four-player quantum
Minority game is investigated. Different time correlated quantum memory
channels are considered to analyze the Nash equilibrium payoff of the 1st
player. It is seen that the Nash equilibrium payoff is substantially enhanced
due to the presence of correlated noise. The behaviour of damping channels
(amplitude damping and phase damping) is approximately similar. However,
bit-phase flip channel heavily influences the minority game as compared to
other channels in the presence of correlated noise. On the other hand, phase
flip channel has a symmetrical behaviour around 50% noise threshold. The
significant reduction in payoffs due to decoherence is well compensated due to
the presence of correlated noise. However, the Nash equilibrium of the game
does not change in the presence of noise. It is seen that in case of
generalized amplitude damping channel, entanglement plays a significant role at
lower level of decoherence. The channel has less dominant effects on the payoff
at higher values of decoherence. Furthermore, amplitude damping and generalized
amplitude damping channels have almost comparable effects at lower level of
decoherence $(p<0.5)$. Therefore, the game deserves careful study during its
implementation due to prominent role of noise for different channels.",1102.5056v2
2011-03-17,Viscous damping of r-modes: Large amplitude saturation,"We analyze the viscous damping of r-mode oscillations of compact stars,
taking into account non-linear viscous effects in the large-amplitude regime.
The qualitatively different cases of hadronic stars, strange quark stars, and
hybrid stars are studied. We calculate the viscous damping times of r-modes,
obtaining numerical results and also general approximate analytic expressions
that explicitly exhibit the dependence on the parameters that are relevant for
a future spindown evolution calculation. The strongly enhanced damping of large
amplitude oscillations leads to damping times that are considerably lower than
those obtained when the amplitude dependence of the viscosity is neglected.
Consequently, large-amplitude viscous damping competes with the gravitational
instability at all physical frequencies and could stop the r-mode growth in
case this is not done before by non-linear hydrodynamic mechanisms.",1103.3521v2
2011-05-01,"Viscous damping of nanobeam resonators: humidity, thermal noise and the paddling effect","The nanobeam resonator is the key mechanical component in the
nano-electromechanical system. In addition to its high frequency originating
from its low dimension, the performance is significantly influenced by the
circumstances, especially at nanoscale where a large surface area of the
material is exposed. Molecular dynamics simulations and theoretical analysis
are used for a quantitative prediction on the damping behavior, such as the
critical damping condition and lifetime, of nanobeam resonators that directly
maps the fluid-structure properties and interaction information into dynamical
behaviors. We show here how the humidity defines the critical damping condition
through viscous forces, marking the transition from under-damping to
over-damping regime at elevated humidity. Novel phenomena such as the thermal
fluctuation and paddling effects are also discussed.",1105.0139v1
2011-06-07,Damping by branching: a bioinspiration from trees,"Man-made slender structures are known to be sensitive to high levels of
vibration, due to their flexibility, which often cause irreversible damage. In
nature, trees repeatedly endure large amplitudes of motion, mostly caused by
strong climatic events, yet with minor or no damage in most cases. A new
damping mechanism inspired by the architecture of trees is here identified and
characterized in the simplest tree-like structure, a Y-shape branched
structure. Through analytical and numerical analyses of a simple
two-degree-of-freedom model, branching is shown to be the key ingredient in
this protective mechanism that we call damping-by-branching. It originates in
the geometrical nonlinearities so that it is specifically efficient to damp out
large amplitudes of motion. A more realistic model, using flexible beam
approximation, shows that the mechanism is robust. Finally, two bioinspired
architectures are analyzed, showing significant levels of damping achieved via
branching with typically 30% of the energy being dissipated in one oscillation.
This concept of damping-by-branching is of simple practical use in the design
of slender flexible structures.",1106.1283v1
2012-06-15,Landau Damping in a Turbulent Setting,"To address the problem of Landau damping in kinetic turbulence, the forcing
of the linearized Vlasov equation by a stationary random source is considered.
It is found that the time-asymptotic density response is dominated by resonant
particle interactions that are synchronized with the source. The energy
consumption of this response is calculated, implying an effective damping rate,
which is the main result of this paper. Evaluating several cases, it is found
that the effective damping rate can differ from the Landau damping rate in
magnitude and also, remarkably, in sign. A limit is demonstrated in which the
density and current become phase-locked, which causes the effective damping to
be negligible; this potentially resolves an energy paradox that arises in the
application of critical balance to a kinetic turbulence cascade.",1206.3415v4
2012-07-17,Asymptotic Dynamics of a Class of Coupled Oscillators Driven by White Noises,"This paper is devoted to the study of the asymptotic dynamics of a class of
coupled second order oscillators driven by white noises. It is shown that any
system of such coupled oscillators with positive damping and coupling
coefficients possesses a global random attractor. Moreover, when the damping
and the coupling coefficients are sufficiently large, the global random
attractor is a one-dimensional random horizontal curve regardless of the
strength of the noises, and the system has a rotation number, which implies
that the oscillators in the system tend to oscillate with the same frequency
eventually and therefore the so called frequency locking is successful. The
results obtained in this paper generalize many existing results on the
asymptotic dynamics for a single second order noisy oscillator to systems of
coupled second order noisy oscillators. They show that coupled damped second
order oscillators with large damping have similar asymptotic dynamics as the
limiting coupled first order oscillators as the damping goes to infinite and
also that coupled damped second order oscillators have similar asymptotic
dynamics as their proper space continuous counterparts, which are of great
practical importance.",1207.3864v1
2013-10-29,Influence of sample geometry on inductive damping measurement methods,"We study the precession frequency and effective damping of patterned
permalloy thin films of different geometry using integrated inductive test
structures. The test structures consist of coplanar wave guides fabricated onto
patterned permalloy stripes of different geometry. The width, length and
position of the permalloy stripe with respect to the center conductor of the
wave guide are varied. The precession frequency and effective damping of the
different devices is derived by inductive measurements in time and frequency
domain in in-plane magnetic fields. While the precession frequencies do not
reveal a significant dependence on the sample geometry we find a decrease of
the measured damping with increasing width of the permalloy centered underneath
the center conductor of the coplanar wave guide. We attribute this effect to an
additional damping contribution due to inhomogeneous line broadening at the
edges of the permalloy stripes which does not contribute to the inductive
signal provided the permalloy stripe is wider than the center conductor.
Consequences for inductive determination of the effective damping using such
integrated reference samples are discussed.",1310.7817v1
2014-04-02,Determination of the cross-field density structuring in coronal waveguides using the damping of transverse waves,"Time and spatial damping of transverse magnetohydrodynamic (MHD) kink
oscillations is a source of information on the cross-field variation of the
plasma density in coronal waveguides. We show that a probabilistic approach to
the problem of determining the density structuring from the observed damping of
transverse oscillations enables us to obtain information on the two parameters
that characterise the cross-field density profile. The inference is performed
by computing the marginal posterior distributions for density contrast and
transverse inhomo- geneity length-scale using Bayesian analysis and damping
ratios for transverse oscillations under the assumption that damping is
produced by resonant absorption. The obtained distributions show that, for
damping times of a few oscillatory periods, low density contrasts and short
inho- mogeneity length scales are more plausible in explaining observations.
This means that valuable information on the cross-field density profile can be
obtained even if the inversion problem, with two unknowns and one observable,
is a mathematically ill-posed problem.",1404.0584v1
2014-04-05,Gilbert damping in noncollinear ferromagnets,"The precession and damping of a collinear magnetization displaced from its
equilibrium are described by the Landau-Lifshitz-Gilbert equation. For a
noncollinear magnetization, it is not known how the damping should be
described. We use first-principles scattering theory to investigate the damping
in one-dimensional transverse domain walls (DWs) of the important ferromagnetic
alloy Ni$_{80}$Fe$_{20}$ and interpret the results in terms of phenomenological
models. The damping is found to depend not only on the magnetization texture
but also on the specific dynamic modes of Bloch and N\'eel DWs. Even in the
highly disordered Ni$_{80}$Fe$_{20}$ alloy, the damping is found to be
remarkably nonlocal.",1404.1488v2
2014-04-14,Distributed Approximate Message Passing for Compressed Sensing,"In this paper, an efficient distributed approach for implementing the
approximate message passing (AMP) algorithm, named distributed AMP (DAMP), is
developed for compressed sensing (CS) recovery in sensor networks with the
sparsity K unknown. In the proposed DAMP, distributed sensors do not have to
use or know the entire global sensing matrix, and the burden of computation and
storage for each sensor is reduced. To reduce communications among the sensors,
a new data query algorithm, called global computation for AMP (GCAMP), is
proposed. The proposed GCAMP based DAMP approach has exactly the same recovery
solution as the centralized AMP algorithm, which is proved theoretically in the
paper. The performance of the DAMP approach is evaluated in terms of the
communication cost saved by using GCAMP. For comparison purpose, thresholding
algorithm (TA), a well known distributed Top-K algorithm, is modified so that
it also leads to the same recovery solution as the centralized AMP. Numerical
results demonstrate that the GCAMP based DAMP outperforms the Modified TA based
DAMP, and reduces the communication cost significantly.",1404.3766v2
2014-12-17,The most metal-rich damped Lyman alpha systems at z>1.5 I: The Data,"We present HIRES observations for 30 damped Lyman alpha systems, selected on
the basis of their large metal column densities from previous, lower resolution
data. The measured metal column densities for Fe, Zn, S, Si, Cr, Mn, and Ni are
provided for these 30 systems. Combined with previously observed large metal
column density damped Lyman alpha systems, we present a sample of 44 damped
Lyman alpha systems observed with high resolution spectrographs (R~30000).
These damped Lyman alpha systems probe the most chemically evolved systems at
redshifts greater than 1.5. We discuss the context of our sample with the
general damped Lyman alpha population, demonstrating that we are probing the
top 10% of metal column densities with our sample. In a companion paper, we
will present an analysis of the sample's elemental abundances in the context of
galactic chemical enrichment.",1412.5491v1
2015-02-16,Role of nonlinear anisotropic damping in the magnetization dynamics of topological solitons,"The consequences of nonlinear anisotropic damping, driven by the presence of
Rashba spin-orbit coupling in thin ferromagnetic metals, are examined for the
dynamics of topological magnetic solitons such as domain walls, vortices, and
skyrmions. The damping is found to affect Bloch and N\'eel walls differently in
the steady state regime below Walker breakdown and leads to a monotonic
increase in the wall velocity above this transition for large values of the
Rashba coefficient. For vortices and skyrmions, a generalization of the damping
tensor within the Thiele formalism is presented. It is found that chiral
components of the damping affect vortex- and hedgehog-like skyrmions in
different ways, but the dominant effect is an overall increase in the
viscous-like damping.",1502.04695v2
2015-03-26,Transient nutations decay in diluted paramagnetic solids: a radiation damping mechanism,"Here, a theory of the intensity and concentration dependent damping of
nutation signals observed by Boscaino et al. (Phys. Rev B 48, 7077 (1993);
Phys. Rev. A 59, 4087 (1999)) and by others in various two-level spin systems
is proposed. It is shown that in diluted paramagnetic solids contribution of
dipole-dipole interaction to the nutation decay is negligibly small. We
elaborated a cavity loss (radiation damping) mechanism that explains the
intensity- and concentration dependence of the damping. It is shown that
instead of ordinary Bloch's transverse T2 and longitudinal T1 damping
parameters the decay of transverse and longitudinal spin components in nutation
process are described by one and the same intensity-, concentration-,
frequency- and time dependent damping parameter.",1503.07641v2
2015-08-17,Increased magnetic damping of a single domain wall and adjacent magnetic domains detected by spin torque diode in a nanostripe,"We use spin-torque resonance to probe simultaneously and separately the
dynamics of a magnetic domain wall and of magnetic domains in a nanostripe
magnetic tunnel junction. Thanks to the large associated resistance variations
we are able to analyze quantitatively the resonant properties of these single
nanoscale magnetic objects. In particular, we find that the magnetic damping of
both domains and domain walls is doubled compared to the damping value of their
host magnetic layer. We estimate the contributions to damping arising from
dipolar couplings between the different layers in the junction and from the
intralayer spin pumping effect. We find that they cannot explain the large
damping enhancement that we observe. We conclude that the measured increased
damping is intrinsic to large amplitudes excitations of spatially localized
modes or solitons such as vibrating or propagating domain walls",1508.04043v1
2016-02-22,Effects of Landau-Lifshitz-Gilbert damping on domain growth,"Domain patterns are simulated by the Landau-Lifshitz-Gilbert (LLG) equation
with an easy-axis anisotropy. If the Gilbert damping is removed from the LLG
equation, it merely describes the precession of magnetization with a
ferromagnetic interaction. However, even without the damping, domains that look
similar to those of scalar fields are formed, and they grow with time. It is
demonstrated that the damping has no significant effects on domain growth laws
and large-scale domain structure. In contrast, small-scale domain structure is
affected by the damping. The difference in small-scale structure arises from
energy dissipation due to the damping.",1602.06673v3
2016-04-27,Influence of nonlocal damping on the field-driven domain wall motion,"We derive the complete expression of nonlocal damping in noncollinear
magnetization due to the nonuniform spin current pumped by precessional
magnetization and incorporate it into a generalized Thiele equation to study
its effects on the dynamics of the transverse and vortex domain walls (DWs) in
ferromagnetic nanowires. We demonstrate that the transverse component of
nonlocal damping slows down the field-driven DW propagation and increases the
Walker breakdown field whereas it is neglected in many previous works in
literature. The experimentally measured DW mobility variation with the damping
tuned by doping with heavy rare-earth elements that had discrepancy from
micromagnetic simulation are now well understood with the nonlocal damping. Our
results suggest that the nonlocal damping should be properly included as a
prerequisite for quantitative studies of current-induced torques in
noncollinear magnetization.",1604.07971v2
2016-04-27,Damping of the Collective Amplitude Mode in Superconductors with Strong Electron-Phonon Coupling,"We study the effect of strong electron-phonon interactions on the damping of
the Higgs amplitude mode in superconductors by means of non-equilibrium
dynamical mean-field simulations of the Holstein model. In contrast to the BCS
dynamics, we find that the damping of the Higgs mode strongly depends on the
temperature, becoming faster as the systen approaches the transition
temperature. The damping at low temperatures is well described by a power-law,
while near the transition temperature the damping shows exponential-like
behavior. We explain this crossover by a temperature-dependent quasiparticle
lifetime caused by the strong electron- phonon coupling, which smears the
superconducting gap edge and makes the relaxation of the Higgs mode into
quasiparticles more efficient at elevated temperatures. We also reveal that the
phonon dynamics can soften the Higgs mode, which results in a slower damping.",1604.08073v2
2016-06-14,Anomalous Damping of a Micro-electro-mechanical Oscillator in Superfluid $^3$He-B,"The mechanical resonance properties of a micro-electro-mechanical oscillator
with a gap of 1.25 $\mu$m was studied in superfluid $^3$He-B at various
pressures. The oscillator was driven in the linear damping regime where the
damping coefficient is independent of the oscillator velocity. The quality
factor of the oscillator remains low ($Q\approx 80$) down to 0.1 $T_c$, 4
orders of magnitude less than the intrinsic quality factor measured in vacuum
at 4 K. In addition to the Boltzmann temperature dependent contribution to the
damping, a damping proportional to temperature was found to dominate at low
temperatures. We propose a multiple scattering mechanism of the surface Andreev
bound states to be a possible cause for the anomalous damping.",1606.04483v2
2018-02-15,Damping's effect on the magnetodynamics of spin Hall nano-oscillators,"We study the impact of spin wave damping ($\alpha$) on the auto-oscillation
properties of nano-constriction based spin Hall nano-oscillators (SHNOs). The
SHNOs are based on a 5 nm Pt layer interfaced to a 5 nm
Py$_{100-x-y}$Pt$_{x}$Ag$_{y}$ magnetic layer, where the Pt and Ag contents are
co-varied to keep the saturation magnetization constant (within 10 %), while
$\alpha$ varies close to a factor of three. We systematically investigate the
influence of the Gilbert damping on the magnetodynamics of these SHNOs by means
of electrical microwave measurements. Under the condition of a constant field,
the threshold current scales with the damping in the magnetic layer. The
threshold current as a function of field shows a parabolic-like behavior, which
we attribute to the evolution of the spatial profile of the auto-oscillation
mode. The signal linewidth is smaller for the high-damping materials in low
magnetic fields, although the lowest observed linewidth was measured for the
alloy with least damping.",1802.05548v1
2020-07-02,Uniformly-Damped Binomial Filters: Five-percent Maximum Overshoot Optimal Response Design,"In this paper, the five-percent maximum overshoot design of uniformly-damped
binomial filters (transfer-functions) is introduced. First, the butterworth
filter response is represented as a damped-binomial filter response. To extend
the maximum-overshoot response of the second-order butterworth to higher
orders, the binomial theorem is extended to the uniformly-damped binomial
theorem. It is shown that the five-percent uniformly-damped binomial filter is
a compromise between the butterworth filter and the standard binomial filter,
with respect to the filter-approximation problem in the time and frequency
domain. Finally, this paper concludes that in applications of interest, such as
step-tracking, where both strong filtering and a fast, smooth
transient-response, with negligible overshoot are desired, the response of the
normalized five-percent uniformly-damped binomial form is a candidate
replacement for both the butterworth and standard binomial filter forms.",2007.00890v3
2014-03-13,The best decay rate of the damped plate equation in a square,"In this paper we study the best decay rate of the solutions of a damped plate
equation in a square and with a homogeneous Dirichlet boundary conditions. We
show that the fastest decay rate is given by the supremum of the real part of
the spectrum of the infinitesimal generator of the underlying semigroup, if the
damping coefficient is in $L^\infty(\Omega).$ Moreover, we give some numerical
illustrations by spectral computation of the spectrum associated to the damped
plate equation. The numerical results obtained for various cases of damping are
in a good agreement with theoretical ones. Computation of the spectrum and
energy of discrete solution of damped plate show that the best decay rate is
given by spectral abscissa of numerical solution.",1403.3199v1
2017-01-19,Decoherence effects on multiplayer cooperative quantum games,"We study the behavior of cooperative multiplayer quantum games [35,36] in the
presence of decoherence using different quantum channels such as amplitude
damping, depolarizing and phase damping. It is seen that the outcomes of the
games for the two damping channels with maximum values of decoherence reduce to
same value. However, in comparison to phase damping channel, the payoffs of
cooperators are strongly damped under the influence\ amplitude damping channel
for\ the lower values of decoherence parameter. In the case of depolarizing
channel, the game is a no-payoff game irrespective of the degree of
entanglement in the initial state for the larger values of decoherence
parameter. The decoherence gets the cooperators worse off.",1701.05342v1
2009-12-20,A Kinetic Alfven wave cascade subject to collisionless damping cannot reach electron scales in the solar wind at 1 AU,"(Abridged) Turbulence in the solar wind is believed to generate an energy
cascade that is supported primarily by Alfv\'en waves or Alfv\'enic
fluctuations at MHD scales and by kinetic Alfv\'en waves (KAWs) at kinetic
scales $k_\perp \rho_i\gtrsim 1$. Linear Landau damping of KAWs increases with
increasing wavenumber and at some point the damping becomes so strong that the
energy cascade is completely dissipated. A model of the energy cascade process
that includes the effects of linear collisionless damping of KAWs and the
associated compounding of this damping throughout the cascade process is used
to determine the wavenumber where the energy cascade terminates. It is found
that this wavenumber occurs approximately when $|\gamma/\omega|\simeq 0.25$,
where $\omega(k)$ and $\gamma(k)$ are, respectively, the real frequency and
damping rate of KAWs and the ratio $\gamma/\omega$ is evaluated in the limit as
the propagation angle approaches 90 degrees relative to the direction of the
mean magnetic field.",0912.4026v2
2011-11-29,Dispersion and damping of potential surface waves in a degenerate plasma,"Potential (electrostatic) surface waves in plasma half-space with degenerate
electrons are studied using the quasi-classical mean-field kinetic model. The
wave spectrum and the collisionless damping rate are obtained numerically for a
wide range of wavelengths. In the limit of long wavelengths, the wave frequency
$\omega$ approaches the cold-plasma limit $\omega=\omega_p/\sqrt{2}$ with
$\omega_p$ being the plasma frequency, while at short wavelengths, the wave
spectrum asymptotically approaches the spectrum of zero-sound mode propagating
along the boundary. It is shown that the surface waves in this system remain
weakly damped at all wavelengths (in contrast to strongly damped surface waves
in Maxwellian electron plasmas), and the damping rate nonmonotonically depends
on the wavelength, with the maximum (yet small) damping occuring for surface
waves with wavelength of $\approx5\pi\lambda_{F}$, where $\lambda_{F}$ is the
Thomas-Fermi length.",1111.6723v1
2012-01-29,Smooth attractors of finite dimension for von Karman evolutions with nonlinear frictional damping localized in a boundary layer,"In this paper dynamic von Karman equations with localized interior damping
supported in a boundary collar are considered. Hadamard well-posedness for von
Karman plates with various types of nonlinear damping are well-known, and the
long-time behavior of nonlinear plates has been a topic of recent interest.
Since the von Karman plate system is of ""hyperbolic type"" with critical
nonlinearity (noncompact with respect to the phase space), this latter topic is
particularly challenging in the case of geometrically constrained and nonlinear
damping. In this paper we first show the existence of a compact global
attractor for finite-energy solutions, and we then prove that the attractor is
both smooth and finite dimensional. Thus, the hyperbolic-like flow is
stabilized asymptotically to a smooth and finite dimensional set.
  Key terms: dynamical systems, long-time behavior, global attractors,
nonlinear plates, nonlinear damping, localized damping",1201.6072v1
2016-05-29,Damped Infinite Energy Solutions of the 3D Euler and Boussinesq Equations,"We revisit a family of infinite-energy solutions of the 3D incompressible
Euler equations proposed by Gibbon et al. [9] and shown to blowup in finite
time by Constantin [6]. By adding a damping term to the momentum equation we
examine how the damping coefficient can arrest this blowup. Further, we show
that similar infinite-energy solutions of the inviscid 3D Boussinesq system
with damping can develop a singularity in finite time as long as the damping
effects are insufficient to arrest the (undamped) 3D Euler blowup in the
associated damped 3D Euler system.",1605.08965v3
2016-12-16,Dynamics of cohering and decohering power under Markovian channels,"In this paper, we investigate the cohering and decohering power for the
one-qubit Markovian channels with respect to coherence in terms of the
$l_{1}$-norm, the R$\acute{e}$nyi $\alpha$-relative entropy and the Tsallis
$\alpha$-relative entropy. In the case of $\alpha=2$, the cohering and
decohering power of the amplitude damping channel, the phase damping channel,
the depolarizing channel, and the flip channels under the three measures of
coherence are calculated analytically. The decohering power on the $x, y, z$
basis referring to the amplitude damping channel, the phase damping channel,
the flip channel for every measure we investigated is equal. This property also
happens in the cohering power of the phase damping channel, the depolarizing
channel, and the flip channels. However, the decohering power of the
depolarizing channel is independent to the reference basis, and the cohering
power of the amplitude damping channel on the $x, y$ basis is different to that
on the $z$ basis.",1612.05355v1
2017-07-30,Blow-up for semilinear damped wave equations with sub-Strauss exponent in the scattering case,"It is well-known that the critical exponent for semilinear damped wave
equations is Fujita exponent when the damping is effective. Lai, Takamura and
Wakasa in 2017 have obtained a blow-up result not only for super-Fujita
exponent but also for the one closely related to Strauss exponent when the
damping is scaling invariant and its constant is relatively small,which has
been recently extended by Ikeda and Sobajima. Introducing a multiplier for the
time-derivative of the spatial integral of unknown functions, we succeed in
employing the technics on the analysis for semilinear wave equations and
proving a blow-up result for semilinear damped wave equations with sub-Strauss
exponent when the damping is in the scattering range.",1707.09583v3
2017-10-09,Resonant absorption of surface sausage and surface kink modes under photospheric conditions,"We study the effect of resonant absorption of surface sausage and surface
kink modes under photospheric conditions where the slow surface sausage modes
undergo resonant damping in the slow continuum and the surface kink modes in
the slow and Alfv\'{e}n continua at the transitional layers. We use recently
derived analytical formulas to obtain the damping rate (time). By considering
linear density and linear pressure profiles for the transitional layers, we
show that resonant absorption in the slow continuum could be an efficient
mechanism for the wave damping of the slow surface sausage and slow surface
kink modes whilst the damping rate of the slow surface kink mode in the
Alfv\'{e}n continuum is weak. It is also found that the resonant damping of the
fast surface kink mode is much stronger than that of the slow surface kink
mode, showing a similar efficiency as under coronal conditions. It is worth to
notice that the slow body sausage and kink modes can also resonantly damp in
the slow continuum for those linear profiles.",1710.03350v2
2018-01-03,Stabilisation of wave equations on the torus with rough dampings,"For the damped wave equation on a compact manifold with {\em continuous}
dampings, the geometric control condition is necessary and sufficient for
{uniform} stabilisation. In this article, on the two dimensional torus, in the
special case where $a(x) = \sum\_{j=1}^N a\_j 1\_{x\in R\_j}$ ($R\_j$ are
polygons), we give a very simple necessary and sufficient geometric condition
for uniform stabilisation. We also propose a natural generalization of the
geometric control condition which makes sense for $L^\infty$ dampings. We show
that this condition is always necessary for uniform stabilisation (for any
compact (smooth) manifold and any $L^\infty$ damping), and we prove that it is
sufficient in our particular case on $\mathbb{T}^2$ (and for our particular
dampings).",1801.00983v2
2019-06-25,Conductivity-Like Gilbert Damping due to Intraband Scattering in Epitaxial Iron,"Confirming the origin of Gilbert damping by experiment has remained a
challenge for many decades, even for simple ferromagnetic metals. In this
Letter, we experimentally identify Gilbert damping that increases with
decreasing electronic scattering in epitaxial thin films of pure Fe. This
observation of conductivity-like damping, which cannot be accounted for by
classical eddy current loss, is in excellent quantitative agreement with
theoretical predictions of Gilbert damping due to intraband scattering. Our
results resolve the longstanding question about a fundamental damping mechanism
and offer hints for engineering low-loss magnetic metals for cryogenic
spintronics and quantum devices.",1906.10326v2
2019-09-21,Stability for coupled waves with locally disturbed Kelvin-Voigt damping,"We consider a coupled wave system with partial Kelvin-Voigt damping in the
interval (-1,1), where one wave is dissipative and the other does not. When the
damping is effective in the whole domain (-1,1) it was proven in H.Portillo
Oquendo and P.Sanez Pacheco, optimal decay for coupled waves with Kelvin-voigt
damping, Applied Mathematics Letters 67 (2017), 16-20. That the energy is
decreasing over the time with a rate equal to $t^{-\frac{1}{2}}$. In this
paper, using the frequency domain method we show the effect of the coupling and
the non smoothness of the damping coefficient on the energy decay. Actually, as
expected we show the lack of exponential stability, that the semigroup loses
speed and it decays polynomially with a slower rate then given in, H.Portillo
Oquendo and P.Sanez Pacheco, optimal decay for coupled waves with Kelvin-voigt
damping, Applied Mathematics Letters 67 (2017), 16-20, down to zero at least as
$t^{-\frac{1}{12}}$.",1909.09838v1
2020-12-25,Information constraint in open quantum systems,"We propose an effect called information constraint which is characterized by
the existence of different decay rates of signal strengths propagating along
opposite directions. It is an intrinsic property of a type of open quantum
system, which does not rely on boundary conditions. We define the value of
information constraint ($I_C$) as the ratio of different decay rates and derive
the analytical representation of $I_C$ for general quadratic Lindbladian
systems. Based on information constraint, we can provide a simple and elegant
explanation of chiral and helical damping, and get the local maximum points of
relative particle number for the periodical boundary system, consistent with
numerical calculations. Inspired by information constraint, we propose and
prove the correspondence between edge modes and damping modes. A new damping
mode called Dirac damping is constructed, and chiral/helical damping can be
regarded as a special case of Dirac damping.",2012.13583v3
2017-11-21,Nonexistence of global solutions of nonlinear wave equations with weak time-dependent damping related to Glassey conjecture,"This work is devoted to the nonexistence of global-in-time energy solutions
of nonlinear wave equation of derivative type with weak time-dependent damping
in the scattering and scale invariant range. By introducing some multipliers to
absorb the damping term, we succeed in establishing the same upper bound of the
lifespan for the scattering damping as the non-damped case, which is a part of
so-called Glassey conjecture on nonlinear wave equations. We also study an
upper bound of the lifespan for the scale invariant damping with the same
method.",1711.07591v2
2018-03-12,Optical Rotation of Levitated Spheres in High Vacuum,"A circularly polarized laser beam is used to levitate and control the
rotation of microspheres in high vacuum. At low pressure, rotation frequencies
as high as 6 MHz are observed for birefringent vaterite spheres, limited by
centrifugal stresses. Due to the extremely low damping in high vacuum,
controlled optical rotation of amorphous SiO$_2$ spheres is also observed at
rates above several MHz. At $10^{-7}$ mbar, a damping time of $6\times10^4$ s
is measured for a $10\ \mu$m diameter SiO$_2$ sphere. No additional damping
mechanisms are observed above gas damping, indicating that even longer damping
times may be possible with operation at lower pressure. The controlled optical
rotation of microspheres at MHz frequencies with low damping, including for
materials that are not intrinsically birefringent, provides a new tool for
performing precision measurements using optically levitated systems.",1803.04297v1
2018-03-23,A conservation law with spatially localized sublinear damping,"We consider a general conservation law on the circle, in the presence of a
sublinear damping. If the damping acts on the whole circle, then the solution
becomes identically zero in finite time, following the same mechanism as the
corresponding ordinary differential equation. When the damping acts only
locally in space, we show a dichotomy: if the flux function is not zero at the
origin, then the transport mechanism causes the extinction of the solution in
finite time, as in the first case. On the other hand, if zero is a
non-degenerate critical point of the flux function, then the solution becomes
extinct in finite time only inside the damping zone, decays algebraically
uniformly in space, and we exhibit a boundary layer, shrinking with time,
around the damping zone. Numerical illustrations show how similar phenomena may
be expected for other equations.",1803.08767v1
2018-06-13,Low magnetic damping of ferrimagnetic GdFeCo alloys,"We investigate the Gilbert damping parameter for rare earth (RE)-transition
metal (TM) ferrimagnets over a wide temperature range. Extracted from the
field-driven magnetic domain-wall mobility, the Gilbert damping parameter was
as low as 0.0072 and was almost constant across the angular momentum
compensation temperature, starkly contrasting previous predictions that the
Gilbert damping parameter should diverge at the angular momentum compensation
temperature due to vanishing total angular momentum. Thus, magnetic damping of
RE-TM ferrimagnets is not related to the total angular momentum but is
dominated by electron scattering at the Fermi level where the TM has a dominant
damping role.",1806.04881v1
2019-03-06,Microwave magnon damping in YIG films at millikelvin temperatures,"Magnon systems used in quantum devices require low damping if coherence is to
be maintained. The ferrimagnetic electrical insulator yttrium iron garnet (YIG)
has low magnon damping at room temperature and is a strong candidate to host
microwave magnon excitations in future quantum devices. Monocrystalline YIG
films are typically grown on gadolinium gallium garnet (GGG) substrates. In
this work, comparative experiments made on YIG waveguides with and without GGG
substrates indicate that the material plays a significant role in increasing
the damping at low temperatures. Measurements reveal that damping due to
temperature-peak processes is dominant above 1 K. Damping behaviour that we
show can be attributed to coupling to two-level fluctuators (TLFs) is observed
below 1 K. Upon saturating the TLFs in the substrate-free YIG at 20 mK,
linewidths of 1.4 MHz are achievable: lower than those measured at room
temperature.",1903.02527v3
2020-05-15,Slow magnetosonic wave absorption by pressure induced ionization-recombination dissipation,"A new mechanisms for damping of slow magnetosonic waves (SMW) by pressure
induced oscillations of the ionization degree is proposed. An explicit formula
for the damping rate is quantitatively derived. Physical conditions where the
new mechanism will dominate are briefly discussed. The ionization-recombination
damping is frequency independent and has no hydrodynamic interpretation.
Roughly speaking large area of partially ionized plasma are damper for basses
of SMW while usual MHD mechanisms operate as a low pass filter. The derived
damping rate is proportional to the square of the sine between the constant
magnetic field and the wave-vector. Angular distribution of the spectral
density of SMW and Alfv\'en waves (AW) created by turbulent regions and passing
through large regions of partially ionized plasma is qualitatively considered.
The calculated damping rate is expressed by the electron impact cross section
of the hydrogen atom and in short all details of the proposed damping
mechanisms are well studied.",2005.07730v1
2020-06-30,Polynomial stabilization of non-smooth direct/indirect elastic/viscoelastic damping problem involving Bresse system,"We consider an elastic/viscoelastic transmission problem for the Bresse
system with fully Dirichlet or Dirichlet-Neumann-Neumann boundary conditions.
The physical model consists of three wave equations coupled in certain pattern.
The system is damped directly or indirectly by global or local Kelvin-Voigt
damping. Actually, the number of the dampings, their nature of distribution
(locally or globally) and the smoothness of the damping coefficient at the
interface play a crucial role in the type of the stabilization of the
corresponding semigroup. Indeed, using frequency domain approach combined with
multiplier techniques and the construction of a new multiplier function, we
establish different types of energy decay rate (see the table of stability
results below). Our results generalize and improve many earlier ones in the
literature and in particular some studies done on the Timoshenko system with
Kelvin-Voigt damping.",2006.16595v2
2020-09-17,Temperature Dependent Non-linear Damping in Palladium Nano-mechanical Resonators,"Advances in nano-fabrication techniques has made it feasible to observe
damping phenomena beyond the linear regime in nano-mechanical systems. In this
work, we report cubic non-linear damping in palladium nano-mechanical
resonators. Nano-scale palladium beams exposed to a $H_2$ atmosphere become
softer and display enhanced Duffing non-linearity as well as non-linear damping
at ultra low temperatures. The damping is highest at the lowest temperatures of
$\sim 110\: mK$ and decreases when warmed up-to $\sim 1\textrm{ }K$. We
experimentally demonstrate for the first time a temperature dependent
non-linear damping in a nano-mechanical system below 1 K. It is consistent with
a predicted two phonon mediated non-linear Akhiezer scenario for ballistic
phonons with mean free path comparable to the beam thickness. This opens up new
possibilities to engineer non-linear phenomena at low temperatures.",2009.08324v1
2020-09-22,Sharp exponential decay rates for anisotropically damped waves,"In this article, we study energy decay of the damped wave equation on compact
Riemannian manifolds where the damping coefficient is anisotropic and modeled
by a pseudodifferential operator of order zero. We prove that the energy of
solutions decays at an exponential rate if and only if the damping coefficient
satisfies an anisotropic analogue of the classical geometric control condition,
along with a unique continuation hypothesis. Furthermore, we compute an
explicit formula for the optimal decay rate in terms of the spectral abscissa
and the long-time averages of the principal symbol of the damping over
geodesics, in analogy to the work of Lebeau for the isotropic case. We also
construct genuinely anisotropic dampings which satisfy our hypotheses on the
flat torus.",2009.10832v2
2021-04-29,Non-linear damping of standing kink waves computed with Elsasser variables,"In a previous paper, we computed the energy density and the non-linear energy
cascade rate for transverse kink waves using Elsasser variables. In this paper,
we focus on the standing kink waves, which are impulsively excited in coronal
loops by external perturbations. We present an analytical calculation to
compute the damping time due to the non-linear development of the
Kelvin-Helmholtz instability. The main result is that the damping time is
inversely proportional to the oscillation amplitude. We compare the damping
times from our formula with the results of numerical simulations and
observations. In both cases we find a reasonably good match. The comparison
with the simulations show that the non-linear damping dominates in the high
amplitude regime, while the low amplitude regime shows damping by resonant
absorption. In the comparison with the observations, we find a power law
inversely proportional to the amplitude $\eta^{-1}$ as an outer envelope for
our Monte Carlo data points.",2104.14331v1
2021-05-31,Revisiting the Plasmon Radiation Damping of Gold Nanorods,"Noble metal nanoparticles have been utilized for a vast amount of optical
applications. For the applications that used metal nanoparticles as nanosensors
and optical labeling, larger radiation damping is preferred (higher optical
signal). To get a deeper knowledge about the radiation damping of noble metal
nanoparticles, we used gold nanorods with different geometry factors (aspect
ratios) as the model system to study. We investigated theoretically how the
radiation damping of a nanorod depends on the material, and shape of the
particle. Surprisingly, a simple analytical equation describes radiation
damping very accurately and allow to disentangle the maximal radiation damping
parameter for gold nanorod with resonance energy E_res around 1.81 eV (685 nm).
We found very good agreement with theoretical predictions and experimental data
obtained by single-particle spectroscopy. Our results and approaches may pave
the way for designing and optimizing gold nanostructure with higher optical
signal and better sensing performance.",2105.14873v1
2021-06-23,Bayesian evidence for a nonlinear damping model for coronal loop oscillations,"Recent observational and theoretical studies indicate that the damping of
solar coronal loop oscillations depends on the oscillation amplitude. We
consider two mechanisms, linear resonant absorption and a nonlinear damping
model. We confront theoretical predictions from these models with observed data
in the plane of observables defined by the damping ratio and the oscillation
amplitude. The structure of the Bayesian evidence in this plane displays a
clear separation between the regions where each model is more plausible
relative to the other. There is qualitative agreement between the regions of
high marginal likelihood and Bayes factor for the nonlinear damping model and
the arrangement of observed data. A quantitative application to 101 loop
oscillation cases observed with SDO/AIA results in the marginal likelihood for
the nonlinear model being larger in the majority of them. The cases with
conclusive evidence for the nonlinear damping model outnumber considerably
those in favor of linear resonant absorption.",2106.12243v1
2021-07-13,Convergence of iterates for first-order optimization algorithms with inertia and Hessian driven damping,"In a Hilbert space setting, for convex optimization, we show the convergence
of the iterates to optimal solutions for a class of accelerated first-order
algorithms. They can be interpreted as discrete temporal versions of an
inertial dynamic involving both viscous damping and Hessian-driven damping. The
asymptotically vanishing viscous damping is linked to the accelerated gradient
method of Nesterov while the Hessian driven damping makes it possible to
significantly attenuate the oscillations. By treating the Hessian-driven
damping as the time derivative of the gradient term, this gives, in discretized
form, first-order algorithms. These results complement the previous work of the
authors where it was shown the fast convergence of the values, and the fast
convergence towards zero of the gradients.",2107.05943v1
2021-12-13,Effect of interfacial damping on high-frequency surface wave resonance on a nanostrip-bonded substrate,"Since surface acoustic waves (SAW) are often generated on substrates to which
nanostrips are periodically attached, it is very important to consider the
effect of interface between the deposited strip and the substrate surface,
which is an unavoidable issue in manufacturing. In this paper, we propose a
theoretical model that takes into account the interface damping and calculate
the dispersion relationships both for frequency and attenuation of SAW
resonance. This results show that the interface damping has an insignificant
effect on resonance frequency, but, interestingly, attenuation of the SAW can
decrease significantly in the high frequency region as the interface damping
increases. Using picosecond ultrasound spectroscopy, we confirm the validity of
our theory; the experimental results show similar trends both for resonant
frequency and attenuation in the SAW resonance. Furthermore, the resonant
behavior of the SAW is simulated using the finite element method, and the
intrinsic cause of interface damping on the vibrating system is discussed.
These findings strongly indicate the necessity of considering interfacial
damping in the design of SAW devices.",2112.06367v1
2021-12-13,Cosmic ray streaming in the turbulent interstellar medium,"We study the streaming instability of GeV$-100~$GeV cosmic rays (CRs) and its
damping in the turbulent interstellar medium (ISM). We find that the damping of
streaming instability is dominated by ion-neutral collisional damping in weakly
ionized molecular clouds, turbulent damping in the highly ionized warm medium,
and nonlinear Landau damping in the Galactic halo. Only in the Galactic halo,
is the streaming speed of CRs close to the Alfv\'{e}n speed. Alfv\'{e}nic
turbulence plays an important role in both suppressing the streaming
instability and regulating the diffusion of streaming CRs via magnetic field
line tangling, with the effective mean free path of streaming CRs in the
observer frame determined by the Alfv\'{e}nic scale in super-Alfv\'{e}nic
turbulence. The resulting diffusion coefficient is sensitive to Alfv\'{e}n Mach
number, which has a large range of values in the multi-phase ISM.
Super-Alfv\'{e}nic turbulence contributes to additional confinement of
streaming CRs, irrespective of the dominant damping mechanism.",2112.06941v2
2022-05-27,Scalar field damping at high temperatures,"The motion of a scalar field that interacts with a hot plasma, like the
inflaton during reheating, is damped, which is a dissipative process. At high
temperatures the damping can be described by a local term in the effective
equation of motion. The damping coefficient is sensitive to multiple
scattering. In the loop expansion its computation would require an all-order
resummation. Instead we solve an effective Boltzmann equation, similarly to the
computation of transport coefficients. For an interaction with another scalar
field we obtain a simple relation between the damping coefficient and the bulk
viscosity, so that one can make use of known results for the latter. The
numerical prefactor of the damping coefficient turns out to be rather large, of
order $ 10 ^ 4 $.",2205.14166v2
2022-09-13,Latest results from the DAMPE space mission,"The DArk Matter Particle Explorer (DAMPE) is a space-based particle detector
launched on December 17th, 2015 from the Jiuquan Satellite Launch Center
(China). The main goals of the DAMPE mission are the study of galactic cosmic
rays (CR), the electron-positron energy spectrum, gamma-ray astronomy, and
indirect dark matter search. Among its sub-detectors, the deep calorimeter
makes DAMPE able to measure electrons and gamma-ray spectra up to 10 TeV, and
CR nuclei spectra up to hundreds of TeV, with unprecedented energy resolution.
This high-energy region is important in order to search for electron-positron
sources, for dark matter signatures in space, and to clarify CR acceleration
and propagation mechanisms inside our galaxy. A general overview of the DAMPE
experiment will be presented in this work, along with its main results and
ongoing activities.",2209.06014v1
2022-10-25,Microscopic structure of electromagnetic whistler wave damping by kinetic mechanisms in hot magnetized Vlasov plasmas,"The kinetic damping mechanism of low frequency transverse perturbations
propagating parallel to the magnetic field in a magnetized warm electron plasma
is simulated by means of electromagnetic (EM) Vlasov simulations. The
short-time-scale damping of the electron magnetohydrodynamic whistler
perturbations and underlying physics of finite electron temperature effect on
its real frequency are recovered rather deterministically, and analyzed. The
damping arises from an interplay between a global (prevailing over entire
phase-space) and the more familiar resonant-electron-specific kinetic damping
mechanisms, both of which preserve entropy but operate distinctly by leaving
their characteristic signatures on an initially coherent finite amplitude
modification of the warm electron equilibrium distribution. The net damping
results from a deterministic thermalization, or phase-mixing process, largely
supplementing the resonant acceleration of electrons at shorter time scales,
relevant to short-lived turbulent EM fluctuations. A kinetic model for the
evolving initial transverse EM perturbation is presented and applied to
signatures of the whistler wave phase-mixing process in simulations.",2210.13764v1
2022-12-02,Equivalence between the energy decay of fractional damped Klein-Gordon equations and geometric conditions for damping coefficients,"We consider damped $s$-fractional Klein--Gordon equations on $\mathbb{R}^d$,
where $s$ denotes the order of the fractional Laplacian. In the one-dimensional
case $d = 1$, Green (2020) established that the exponential decay for $s \geq
2$ and the polynomial decay of order $s/(4-2s)$ hold if and only if the damping
coefficient function satisfies the so-called geometric control condition. In
this note, we show that the $o(1)$ energy decay is also equivalent to these
conditions in the case $d=1$. Furthermore, we extend this result to the
higher-dimensional case: the logarithmic decay, the $o(1)$ decay, and the
thickness of the damping coefficient are equivalent for $s \geq 2$. In
addition, we also prove that the exponential decay holds for $0 < s < 2$ if and
only if the damping coefficient function has a positive lower bound, so in
particular, we cannot expect the exponential decay under the geometric control
condition.",2212.01029v4
2023-01-13,An artificially-damped Fourier method for dispersive evolution equations,"Computing solutions to partial differential equations using the fast Fourier
transform can lead to unwanted oscillatory behavior. Due to the periodic nature
of the discrete Fourier transform, waves that leave the computational domain on
one side reappear on the other and for dispersive equations these are typically
high-velocity, high-frequency waves. However, the fast Fourier transform is a
very efficient numerical tool and it is important to find a way to damp these
oscillations so that this transform can still be used. In this paper, we
accurately model solutions to four nonlinear partial differential equations on
an infinite domain by considering a finite interval and implementing two
damping methods outside of that interval: one that solves the heat equation and
one that simulates rapid exponential decay. Heat equation-based damping is best
suited for small-amplitude, high-frequency oscillations while exponential decay
is used to damp traveling waves and high-amplitude oscillations. We demonstrate
significant improvements in the runtime of well-studied numerical methods when
adding in the damping method.",2301.05789v1
2023-03-07,Stabilization of the wave equation on larger-dimension tori with rough dampings,"This paper deals with uniform stabilization of the damped wave equation. When
the manifold is compact and the damping is continuous, the geometric control
condition is known to be necessary and sufficient. In the case where the
damping is a sum of characteristic functions of polygons on a two-dimensional
torus, a result by Burq-G\'erard states that stabilization occurs if and only
if every geodesic intersects the interior of the damped region or razes damped
polygons on both sides. We give a natural generalization of their result to a
sufficient condition on tori of any dimension $d \geq 3$. In some particular
cases, we show that this sufficient condition can be weakened.",2303.03733v4
2023-07-10,The Characteristic Shape of Damping Wings During Reionization,"Spectroscopic analysis of Ly$\alpha$ damping wings of bright sources at $z>6$
is a promising way to measure the reionization history of the universe.
However, the theoretical interpretation of the damping wings is challenging due
to the inhomogeneous nature of the reionization process and the proximity
effect of bright sources. In this Letter, we analyze the damping wings arising
from the neutral patches in the radiative transfer cosmological simulation
suite Cosmic Reionization on Computers (CROC). We find that the damping wing
profile remains a tight function of volume-weighted neutral fraction $\left<
x_{\rm HI} \right>_{\rm v}$, especially when $\left< x_{\rm HI} \right>_{\rm
v}>0.5$, despite the patchy nature of reionization and the proximity effect.
This small scatter indicates that with a well-measured damping wing profile, we
could constrain the volume-weighted neutral fraction as precise as $\Delta
\left< x_{\rm HI} \right>_{\rm v} \lesssim 0.1$ in the first half of
reionization.",2307.04797v1
2023-07-17,Dissipation in solids under oscillatory shear: Role of damping scheme and sample thickness,"We study dissipation as a function of sample thickness in solids under global
oscillatory shear applied to the top layer of the sample. Two types of damping
mechanism are considered: Langevin and Dissipative Particle Dynamics (DPD). In
the regime of low driving frequency, and under strain-controlled conditions, we
observe that for Langevin damping, dissipation increases with sample thickness,
while for DPD damping, it decreases. Under force-controlled conditions,
dissipation increases with sample thickness for both damping schemes. These
results can be physically understood by treating the solid as a one-dimensional
harmonic chain in the quasi-static limit, for which explicit equations (scaling
relations) describing dissipation as a function of chain length (sample
thickness) are provided. The consequences of these results, in particular
regarding the choice of damping scheme in computer simulations, are discussed.",2307.08413v1
2023-08-17,A low-rank algorithm for strongly damped wave equations with visco-elastic damping and mass terms,"Damped wave equations have been used in many real-world fields. In this
paper, we study a low-rank solution of the strongly damped wave equation with
the damping term, visco-elastic damping term and mass term. Firstly, a
second-order finite difference method is employed for spatial discretization.
Then, we receive a second-order matrix differential system. Next, we transform
it into an equivalent first-order matrix differential system, and split the
transformed system into three subproblems. Applying a Strang splitting to these
subproblems and combining a dynamical low-rank approach, we obtain a low-rank
algorithm. Numerical experiments are reported to demonstrate that the proposed
low-rank algorithm is robust and accurate, and has second-order convergence
rate in time.",2308.08888v2
2023-10-30,Optimal backward uniqueness and polynomial stability of second order equations with unbounded damping,"For general second order evolution equations, we prove an optimal condition
on the degree of unboundedness of the damping, that rules out finite-time
extinction. We show that control estimates give energy decay rates that
explicitly depend on the degree of unboundedness, and establish a dilation
method to turn existing control estimates for one propagator into those for
another in the functional calculus. As corollaries, we prove Schr\""odinger
observability gives decay for unbounded damping, weak monotonicity in damping,
and quantitative unique continuation and optimal propagation for fractional
Laplacians. As applications, we establish a variety of novel and explicit
energy decay results to systems with unbounded damping, including singular
damping, linearised gravity water waves and Euler--Bernoulli plates.",2310.19911v1
2023-11-27,Gilbert damping in two-dimensional metallic anti-ferromagnets,"A finite spin life-time of conduction electrons may dominate Gilbert damping
of two-dimensional metallic anti-ferromagnets or anti-ferromagnet/metal
heterostructures. We investigate the Gilbert damping tensor for a typical
low-energy model of a metallic anti-ferromagnet system with honeycomb magnetic
lattice and Rashba spin-orbit coupling for conduction electrons. We distinguish
three regimes of spin relaxation: exchange-dominated relaxation for weak
spin-orbit coupling strength, Elliot-Yafet relaxation for moderate spin-orbit
coupling, and Dyakonov-Perel relaxation for strong spin-orbit coupling. We
show, however, that the latter regime takes place only for the in-plane Gilbert
damping component. We also show that anisotropy of Gilbert damping persists for
any finite spin-orbit interaction strength provided we consider no spatial
variation of the N\'eel vector. Isotropic Gilbert damping is restored only if
the electron spin-orbit length is larger than the magnon wavelength. Our theory
applies to MnPS3 monolayer on Pt or to similar systems.",2311.16268v2
2024-01-18,Real-space nonlocal Gilbert damping from exchange torque correlation applied to bulk ferromagnets and their surfaces,"In this work we present an ab initio scheme based on linear response theory
of exchange torque correlation, implemented into the real-space
Korringa-Kohn-Rostoker (RS-KKR) framework to calculate diagonal elements of the
atomic-site-dependent intrinsic Gilbert damping tensor. The method is first
applied to bcc iron and fcc cobalt bulk systems. Beside reproducing earlier
results from the literature for those bulk magnets, the effect of the lattice
compression is also studied for Fe bulk, and significant changes for the
Gilbert damping are found. Furthermore, (001)-oriented surfaces of Fe and Co
are also investigated. It is found that the on-site Gilbert damping increases
in the surface atomic layer and decreases in the subsurface layer, and
approaches the bulk value moving further inside the magnets. Realistic atomic
relaxation of the surface layers enhances the identified effects. The
first-neighbor damping parameters are extremely sensitive to the surface
relaxation. Despite their inhomogeneity caused by the surface, the transverse
Gilbert damping tensor components remain largely insensitive to the
magnetization direction.",2401.09938v2
2024-03-12,"Modulational instability of nonuniformly damped, broad-banded waves: applications to waves in sea-ice","This paper sets out to explore the modulational (or Benjamin-Feir)
instability of a monochromatic wave propagating in the presence of damping such
as that induced by sea-ice on the ocean surface. The fundamental wave motion is
modelled using the spatial Zakharov equation, to which either uniform or
non-uniform (frequency dependent) damping is added. By means of mode truncation
the spatial analogue of the classical Benjamin-Feir instability can be studied
analytically using dynamical systems techniques. The formulation readily yields
the free surface envelope, giving insight into the physical implications of
damping on the modulational instability. The evolution of an initially unstable
mode is also studied numerically by integrating the damped, spatial Zakharov
equation, in order to complement the analytical theory. This sheds light on the
effects of damping on spectral broadening arising from this instability.",2403.07425v1
2015-08-07,Algebraic structure of the Lorentz and of the Poincaré Lie algebras,"We start with the Lorentz algebra $ L=o_{R}(1,3)$ over the reals and find a
suitable basis $B$ relative to which the structure constants are integers. Thus
we consider the $Z$-algebra $L_{Z}$ which is free as a $Z$-module and its
$Z$-basis is $B$. This allows us to define the Lorentz type algebra
$L_K:=L_{Z}\otimes_{Z} K$ over any field $K$. In a similar way, we consider
Poincar\'e type algebras over any field $K$. In this paper we study the ideal
structure of Lorentz and of Poincar\'e type algebras over different fields. It
turns out that Lorentz type algebras are simple if and only if the ground field
has no square root of $-1$. Thus, they are simple over the reals but not over
the complex. Also, if the ground field is of characteristic $2$ then Lorentz
and Poincar\'e type algebras are neither simple nor semisimple. We extend the
study of simplicity of the Lorentz algebra to the case of a ring of scalars
where we have to use the notion of $m$-simplicity (relative to a maximal ideal
$m$ of the ground ring of scalars). The Lorentz type algebras over a finite
field $F_q$ where $q=p^n$ and $p$ is odd are simple if and only if $n$ is odd
and $p$ of the form $p=4k+3$. In case $p=2$ then the Lorentz type algebra are
not simple. Once we know the ideal structure of the algebras, we get some
information of their automorphism groups. For the Lorentz type algebras (except
in the case of characteristic $2$) we describe the affine group scheme of
automorphisms and the derivation algebras. For the Poincar\'e algebras we
restrict this program to the case of an algebraically closed field of
characteristic other than $2$.",1508.01634v1
2017-10-06,Improved bound on isotropic Lorentz violation in the photon sector from extensive air showers,"Cosmic rays have extremely high particle energies (up to $10^{20} \;
\text{eV}$) and can be used to search for violations of Lorentz invariance. We
consider isotropic nonbirefringent Lorentz violation in the photon sector for
the case of a photon velocity larger than the maximum attainable velocity of
the standard fermions. Up to now, Earth-based bounds on this type of Lorentz
violation have been determined from observations of TeV gamma rays. Here, we
elaborate on a novel approach to test Lorentz invariance with greatly improved
sensitivity. This approach is based on investigating extensive air showers
which are induced by cosmic-ray particles in the Earth's atmosphere. We study
the impact of two Lorentz-violating decay processes on the longitudinal
development of air showers, notably the atmospheric depth of the shower maximum
$X_\text{max}$. Specifically, the two Lorentz-violating decay processes
considered are photon decay into an electron-positron pair and modified
neutral-pion decay into two photons. We use Monte Carlo simulations performed
with the CONEX code which was extended to include these two Lorentz-violating
decay processes at a magnitude allowed by the best previous Earth-based bound.
Compared to standard physics, these Lorentz-violating decay processes reduce
the average $X_\text{max}$ for showers with primary energies above
$10^{18}\;\text{eV}$ by an amount that is significantly larger than the average
resolution of current air shower experiments. Comparing the simulations of the
average $X_\text{max}$ to observations, new Earth-based bounds on this type of
Lorentz violation are obtained, which are better than the previous bounds by
more than three orders of magnitude. Prospects of further studies are also
discussed.",1710.02507v4
2020-11-30,Role of Compressive Viscosity and Thermal Conductivity on the Damping of Slow Waves in the Coronal Loops With and Without Heating-Cooling Imbalance,"In the present paper, we derive a new dispersion relation for slow
magnetoacoustic waves invoking the effect of thermal conductivity, compressive
viscosity, radiation and unknown heating term along with the consideration of
heating cooling imbalance from linearized MHD equations. We solve the general
dispersion relation to understand role of compressive viscosity and thermal
conductivity in damping of the slow waves in coronal loops with and without
heating cooling imbalance. We have analyzed wave damping for the range of loop
length $L$=50-500 Mm, temperature $T$=5-30 MK, and density
$\rho$=10$^{-11}$-10$^{-9}$ kg m$^{-3}$. It was found that inclusion of
compressive viscosity along with thermal conductivity significantly enhances
the damping of fundamental mode oscillations in shorter (e.g., $L$=50 Mm) and
super-hot ($T>$10 MK) loops. However, role of the viscosity in damping is
insignificant in longer (e.g., $L$=500 Mm) and hot loops (T$\leq$10 MK) where,
instead, thermal conductivity along with the presence of heating cooling
imbalance plays a dominant role. For the shorter loops at the super-hot regime
of the temperature, increment in loop density substantially enhances damping of
the fundamental modes due to thermal conductivity when the viscosity is absent,
however, when the compressive viscosity is added the increase in density
substantially weakens damping. Thermal conductivity alone is found to play a
dominant role in longer loops at lower temperatures (T$\leq$10 MK), while
compressive viscosity dominates in damping at super-hot temperatures ($T>$10
MK) in shorter loops. The predicted scaling law between damping time ($\tau$)
and wave period ($P$) is found to better match to observed SUMER oscillations
when heating cooling imbalance is taken into account in addition to thermal
conductivity and compressive viscosity for the damping of the fundamental slow
mode oscillations.",2011.14519v2
2003-09-05,Altered Luminosity Functions of Relativistically Beamed Jet Populations,"The intrinsic luminosity functions of extremely fast jets found in many
active galaxies and gamma-ray bursts are difficult to measure since their
apparent luminosities are strongly affected by relativistic beaming. Past
studies have only provided analytical predictions for the beamed
characteristics of populations in which all jets have the same Lorentz factor.
However, the jets found in active galaxies are known to span a large range of
speeds. Here we derive analytical expressions for the expected Doppler factor
distributions and apparent (beamed) luminosity functions of randomly-oriented,
two-sided jet populations which have bulk Lorentz factors distributed according
to a simple power-law over a range [G1, G2]. We find that if a jet population
has a uniform or inverted Lorentz factor distribution, its Doppler factor
distribution and beamed luminosity function will be very similar to that of a
jet population with Lorentz factors all equal to G2. In particular, the beamed
and intrinsic luminosity functions will have the same slope at high
luminosities. In the case of a steeply declining Lorentz factor distribution,
the slopes at high luminosities will also be identical, but only up to an
apparent luminosity equivalent to the upper cutoff of the intrinsic luminosity
function. Also, at very high apparent luminosities, the slope will be
proportional to the power law slope of the Lorentz factor distribution. At very
low luminosities, the form of the apparent luminosity function is very
sensitive to the lower cutoff and steepness of the Lorentz factor distribution.
We discuss how it should be possible to recover useful information about the
intrinsic luminosity functions of relativistic jets by studying flux-limited
samples selected on the basis of beamed jet emission.",0309182v1
2001-09-05,Acoustics in Bose--Einstein condensates as an example of Lorentz symmetry breaking,"To help focus ideas regarding possible routes to the breakdown of Lorentz
invariance, it is extremely useful to explore concrete physical models that
exhibit similar phenomena. In particular, acoustics in Bose--Einstein
condensates has the interesting property that at low-momentum the phonon
dispersion relation can be written in a ``relativistic'' form exhibiting an
approximate ``Lorentz invariance''. Indeed all of low-momentum phonon physics
in this system can be reformulated in terms of relativistic curved-space
quantum field theory. In contrast, high-momentum phonon physics probes regions
where the dispersion relation departs from the relativistic form and thus
violates Lorentz invariance. This model provides a road-map of at least one
route to broken Lorentz invariance. Since the underlying theory is manifestly
physical this type of breaking automatically avoids unphysical features such as
causality violations. This model hints at the type of dispersion relation that
might be expected at ultra-high energies, close to the Planck scale, where
quantum gravity effects are suspected to possibly break ordinary Lorentz
invariance.",0109033v1
2005-11-17,Nonlinear QED and Physical Lorentz Invariance,"The spontaneous breakdown of 4-dimensional Lorentz invariance in the
framework of QED with the nonlinear vector potential constraint
A_{\mu}^{2}=M^{2}(where M is a proposed scale of the Lorentz violation) is
shown to manifest itself only as some noncovariant gauge choice in the
otherwise gauge invariant (and Lorentz invariant) electromagnetic theory. All
the contributions to the photon-photon, photon-fermion and fermion-fermion
interactions violating the physical Lorentz invariance happen to be exactly
cancelled with each other in the manner observed by Nambu a long ago for the
simplest tree-order diagrams - the fact which we extend now to the one-loop
approximation and for both the time-like (M^{2}>0) and space-like (M^{2}<0)
Lorentz violation. The way how to reach the physical breaking of the Lorentz
invariance in the pure QED case taken in the flat Minkowskian space-time is
also discussed in some detail.",0511178v6
2007-02-26,Abelian decomposition of Einstein's theory: Reformulation of general relativity,"We propose a reformulation of general relativity by making the Abelian
decomposition of Einstein's theory. Based on the view that Einstein's theory
can be interpreted as a gauge theory of Lorentz group, we decompose the
Einstein's gravitational connection (the gauge potential of Lorentz group
$\vGm_\mu$) into the restricted connection made of the potential of the maximal
Abelian subgroup $H$ of Lorentz group $G$ and the valence connection made of
$G/H$ part of the potential which transforms covariantly under Lorentz group.
With this decomposition we show that the Einstein's theory can be decomposed
into the restricted part made of the restricted connection which has the full
Lorentz gauge invariance and the valence part made of the valence connection
which plays the role of gravitational source of the restricted gravity. We show
that there are two different Abelian decomposition of Einstein's theory,
because Lorentz group has two maximal Abelian subgroups. In this decomposition
the role of the space-time metric $g_\mn$ is replaced by a four-index metric
tensor $\vg_\mn$ which transforms covariantly under the Lorentz group, and the
metric-compatibility condition $\nabla_\alpha g_\mn=0$ of the connection is
replaced by the gauge covariant condition $D_\mu \vg^\mn$ which tells that
$\vg_\mn$ is invariant under the parallel transport along the
$\pro_\mu$-direction defined by $\vGm_\mu$. We discuss the physical
implications of the Abelian decomposition. In particular, we argue that the
decomposition implies the existence of a restricted theory of gravitation which
has the full general invariance but has less physical degrees of freedom.",0702200v3
2006-08-30,The Lorentz Boost-Link Is Not Unique. Relative velocity as a morphism in a connected groupoid category of null objects,"The isometry-link problem is to determine all isometry transformations among
given pair of vectors with the condition that if these initial and final
vectors coincide, the transformation-link must be identity on entire vector
space. In the first part of this essay we provide the complete solution for the
link problem for arbitrary isometry, for any dimension and arbitrary signature
of the invertible metric tensor.
  We apply these considerations for pure Lorentz transformations, for the
Lorentz boost, parameterized by relative velocity, and we are showing that the
isometric pure Lorentz transformation-link is not given uniquely by the initial
and final vectors. Lorentz's boost needs a choice of the preferred time-like
observer. This leads to non-uniqueness of the relative velocity among two
reference systems, that was apparently not intention of Einstein in 1905.
Presently, as during the XX century, the Lorentz covariance is the cornerstone
of physical theory. Our main conclusion is: observer-dependence (and
-independence), and the Lorentz--covariance (and invariance), are different
concepts.
  In order to have axiomatically the unique relative velocity among pair of
massive bodies, we propose a connected groupoid category of massive bodies in
mutual motions",0608062v1
1997-09-04,"Lorentz Symmetry Violation, Vacuum and Superluminal Particles","If textbook Lorentz invariance is actually a property of the equations
describing a sector of the excitations of vacuum above some critical distance
scale, several sectors of matter with different critical speeds in vacuum can
coexist and an absolute rest frame (the vacuum rest frame) may exist without
contradicting the apparent Lorentz invariance felt by ""ordinary"" particles
(particles with critical speed in vacuum equal to $c$, the speed of light).
Sectorial Lorentz invariance, reflected by the fact that all particles of a
given dynamical sector have the same critical speed in vacuum, will then be an
expression of a fundamental sectorial symmetry (e.g. preonic grand unification
or extended supersymmetry) protecting a parameter of the equations of motion.
Furthermore, the sectorial Lorentz symmetry may be only a low-energy limit, in
the same way as the relation $\omega $ (frequency) = $c_s$ (speed of sound) $k$
(wave vector) holds for low-energy phonons in a crystal. We show that, in this
context, phenomena such as the absence of Greisen-Zatsepin-Kuzmin cutoff and
the stability of unstable particles at very high energy are basic properties of
a wide class of noncausal models where local Lorentz invariance is broken
introducing a fundamental length. Then, observable phenomena are produced at
the wavelength scale of the highest-energy cosmic rays or even below this
energy, but Lorentz symmetry violation remains invisible to standard low-energy
tests. We discuss possible theoretical, phenomenological, experimental and
cosmological implications of this new approach to matter and space-time, as
well as prospects for future developments.",9709006v1
2009-05-14,Einstein-aether as a quantum effective field theory,"The possibility that Lorentz symmetry is violated in gravitational processes
is relatively unconstrained by experiment, in stark contrast with the level of
accuracy to which Lorentz symmetry has been confirmed in the matter sector. One
model of Lorentz violation in the gravitational sector is Einstein-aether
theory, in which Lorentz symmetry is broken by giving a vacuum expectation
value to a dynamical vector field. In this paper we analyse the effective
theory for quantised gravitational and aether perturbations. We show that this
theory possesses a controlled effective expansion within dimensional
regularisation, that is, for any process there are a finite number of Feynman
diagrams which will contribute to a given order of accuracy. We find that there
is no log-running of the two-derivative phenomenological parameters, justifying
the use of experimental constraints for these parameters obtained over many
orders of magnitude in energy scale. Given the stringent experimental bounds on
two-derivative Lorentz-violating operators, we estimate the size of matter
Lorentz-violation which arises due to loop effects. This amounts to an
estimation of the natural size of coefficients for Lorentz-violating
dimension-six matter operators, which in turn can be used to obtain a new bound
on the two-derivative parameters of this theory.",0905.2446v1
2010-06-21,Matter-gravity couplings and Lorentz violation,"The gravitational couplings of matter are studied in the presence of Lorentz
and CPT violation. At leading order in the coefficients for Lorentz violation,
the relativistic quantum hamiltonian is derived from the gravitationally
coupled minimal Standard-Model Extension. For spin-independent effects, the
nonrelativistic quantum hamiltonian and the classical dynamics for test and
source bodies are obtained. A systematic perturbative method is developed to
treat small metric and coefficient fluctuations about a Lorentz-violating and
Minkowski background. The post-newtonian metric and the trajectory of a test
body freely falling under gravity in the presence of Lorentz violation are
established. An illustrative example is presented for a bumblebee model. The
general methodology is used to identify observable signals of Lorentz and CPT
violation in a variety of gravitational experiments and observations, including
gravimeter measurements, laboratory and satellite tests of the weak equivalence
principle, antimatter studies, solar-system observations, and investigations of
the gravitational properties of light. Numerous sensitivities to coefficients
for Lorentz violation can be achieved in existing or near-future experiments at
the level of parts in 10^3 down to parts in 10^{15}. Certain coefficients are
uniquely detectable in gravitational searches and remain unmeasured to date.",1006.4106v2
2010-10-25,On Lorentz violation in Horava-Lifshitz type theories,"We show that coupling the Standard Model to a Lorentz symmetry violating
sector may co-exist with viable phenomenology, provided that the interaction
between the two is mediated by higher-dimensional operators. In particular, if
the new sector acquires anisotropic scaling behavior above a ""Horava-Lifshitz""
energy scale L_HL and couples to the Standard Model through interactions
suppressed by M_P, the transmission of the Lorentz violation into the Standard
Model is protected by the ratio L_HL^2/M_P^2. A wide scale separation,
L_HL<<M_P, can then make Lorentz-violating terms in the Standard Model sector
within experimental bounds without fine-tuning. We first illustrate our point
with a toy example of Lifshitz-type neutral fermion coupled to photon via the
magnetic moment operator, and then implement similar proposal for the
Ho\v{r}ava-Lifshitz gravity coupled to conventional Lorentz-symmetric matter
fields. We find that most radiatively induced Lorentz violation can be
controlled by a large scale separation, but the existence of instantaneously
propagating non-Lifshitz modes in gravity can cause a certain class of diagrams
to remain quadratically divergent above L_HL. Such problematic quadratic
divergence, however, can be removed by extending the action with terms of
higher Lifshitz dimension, resulting in a completely consistent setup that can
cope with the stringent tests of Lorentz invariance.",1010.5249v3
2010-12-08,Lorentz covariance of loop quantum gravity,"The kinematics of loop gravity can be given a manifestly Lorentz-covariant
formulation: the conventional SU(2)-spin-network Hilbert space can be mapped to
a space K of SL(2,C) functions, where Lorentz covariance is manifest. K can be
described in terms of a certain subset of the ""projected"" spin networks studied
by Livine, Alexandrov and Dupuis. It is formed by SL(2,C) functions completely
determined by their restriction on SU(2). These are square-integrable in the
SU(2) scalar product, but not in the SL(2,C) one. Thus, SU(2)-spin-network
states can be represented by Lorentz-covariant SL(2,C) functions, as
two-component photons can be described in the Lorentz-covariant Gupta-Bleuler
formalism. As shown by Wolfgang Wieland in a related paper, this manifestly
Lorentz-covariant formulation can also be directly obtained from canonical
quantization. We show that the spinfoam dynamics of loop quantum gravity is
locally SL(2,C)-invariant in the bulk, and yields states that are preciseley in
K on the boundary. This clarifies how the SL(2,C) spinfoam formalism yields an
SU(2) theory on the boundary. These structures define a tidy Lorentz-covariant
formalism for loop gravity.",1012.1739v3
2011-02-17,Abelian Decomposition of General Relativity,"Based on the view that Einstein's theory can be interpreted as a gauge theory
of Lorentz group, we decompose the gravitational connection (the gauge
potential of Lorentz group) $\vGm_\mu$ into the restricted connection made of
the potential of the maximal Abelian subgroup $H$ of Lorentz group $G$ and the
valence connection made of $G/H$ part of the potential which transforms
covariantly under Lorentz gauge transformation. With this decomposition we show
that the Einstein's theory can be decomposed into the restricted part made of
the restricted connection which has the full Lorentz gauge invariance and the
valence part made of the valence connection which plays the role of
gravitational source of the restricted gravity. We show that there are two
different Abelian decomposition of Einstein's theory, the light-like (or null)
decomposition and the non light-like (or non-null) decomposition, because
Lorentz group has two maximal Abelian subgroups. In this decomposition the role
of the metric $g_\mn$ is replaced by a four-index metric tensor $\vg_\mn$ which
transforms covariantly under the Lorentz group, and the metric-compatibility
condition $\nabla_\alpha g_\mn=0$ of the connection is replaced by the gauge
and generally covariant condition ${\mathscr D}_\mu \vg^\mn=0$. The
decomposition shows the existence of a restricted theory of gravitation which
has the full general invariance but is much simpler and has less physical
degrees of freedom than Einstein's theory. Moreover, it tells that the
restricted gravity can be written as an Abelian gauge theory, which implies
that the graviton can be described by a massless spin-one field.",1102.3490v1
2011-05-20,A new look at Lorentz-Covariant Loop Quantum Gravity,"In this work, we study the classical and quantum properties of the unique
commutative Lorentz-covariant connection for loop quantum gravity. This
connection has been found after solving the second-class constraints inherited
from the canonical analysis of the Holst action without the time-gauge. We show
that it has the property of lying in the conjugacy class of a pure $\su(2)$
connection, a result which enables one to construct the kinematical Hilbert
space of the Lorentz-covariant theory in terms of the usual $\SU(2)$
spin-network states. Furthermore, we show that there is a unique
Lorentz-covariant electric field, up to trivial and natural equivalence
relations. The Lorentz-covariant electric field transforms under the adjoint
action of the Lorentz group, and the associated Casimir operators are shown to
be proportional to the area density. This gives a very interesting algebraic
interpretation of the area. Finally, we show that the action of the surface
operator on the Lorentz-covariant holonomies reproduces exactly the usual
discrete $\SU(2)$ spectrum of time-gauge loop quantum gravity. In other words,
the use of the time-gauge does not introduce anomalies in the quantum theory.",1105.4194v2
2011-10-16,Background Dependent Lorentz Violation: Natural Solutions to the Theoretical Challenges of the OPERA Experiment,"To explain both the OPERA experiment and all the known phenomenological
constraints/observations on Lorentz violation, the Background Dependent Lorentz
Violation (BDLV) has been proposed. We study the BDLV in a model independent
way, and conjecture that there may exist a ""Dream Special Relativity Theory"",
where all the Standard Model (SM) particles can be subluminal due to the
background effects. Assuming that the Lorentz violation on the Earth is much
larger than those on the interstellar scale, we automatically escape all the
astrophysical constraints on Lorentz violation. For the BDLV from the effective
field theory, we present a simple model and discuss the possible solutions to
the theoretical challenges of the OPERA experiment such as the Bremsstrahlung
effects for muon neutrinos and the pion decays. Also, we address the Lorentz
violation constraints from the LEP and KamLAMD experiments. For the BDLV from
the Type IIB string theory with D3-branes and D7-branes, we point out that the
D3-branes are flavour blind, and all the SM particles are the conventional
particles as in the traditional SM when they do not interact with the
D3-branes. Thus, we not only can naturally avoid all the known phenomenological
constraints on Lorentz violation, but also can naturally explain all the
theoretical challenges. Interestingly, the energy dependent photon velocities
may be tested at the experiments.",1110.3451v2
2012-11-24,Parameters of Lorentz Matrices and Transitivity in Polarization Optics,"In the context of applying the Lorentz group theory to polarization optics in
the frames of Stokes-Mueller formalism, some properties of the Lorentz group
are investigated. We start with the factorized form of arbitrary Lorentz matrix
as a product of two commuting and conjugate $4\times 4$-matrices, $L(q,q)=
A(q_{a}) A^*(q_{a}); a= 0,1,2,3$. Mueller matrices of the Lorentzian type M=L
are pointed out as a special sub-class i n the total set of $4\times 4$
matrices of the linear group GL(4,R). Any arbitrary Lorentz matrix is presented
as a linear combination of 16 elements of the Dirac basis. On this ground, a
method to construct parameters q_a by an explicitly given Lorentz matrix L is
elaborated. It is shown that the factorized form of L=M matrices provides us
with a number of simple transitivity equations relating couples of initial and
final 4-vectors, which are defined in terms of parameters q_a of the Lorentz
group. Some of these transitivity relations can be interpreted within
polarization optics and can be applied to the group-theoretic analysis of the
problem of measuring Mueller matrices in optical experiments.",1211.5667v1
2014-12-22,Direct Terrestrial Test of Lorentz Symmetry in Electrodynamics to 10$^{-18}$,"Lorentz symmetry is a foundational property of modern physics, underlying the
standard model of particles and general relativity. It is anticipated that
these two theories are low energy approximations of a single theory that is
unified and consistent at the Planck scale. Many unifying proposals allow
Lorentz symmetry to be broken, with observable effects appearing at
Planck-suppressed levels; thus precision tests of Lorentz invariance are needed
to assess and guide theoretical efforts. Here, we use ultra-stable oscillator
frequency sources to perform a modern Michelson-Morley experiment and make the
most precise direct terrestrial test to date of Lorentz symmetry for the
photon, constraining Lorentz violating orientation-dependent relative frequency
changes $\Delta\nu$/$\nu$ to 9.2$\pm$10.7$\times10^{-19}$ (95$\%$ confidence
interval). This order of magnitude improvement over previous Michelson-Morley
experiments allows us to set comprehensive simultaneous bounds on nine boost
and rotation anisotropies of the speed of light, finding no significant
violations of Lorentz symmetry.",1412.6954v2
2015-11-24,Why is High Energy Physics Lorentz Invariant?,"Despite the tremendous empirical success of equivalence principle, there are
several theoretical motivations for existence of a preferred reference frame
(or aether) in a consistent theory of quantum gravity. However, if quantum
gravity had a preferred reference frame, why would high energy processes enjoy
such a high degree of Lorentz symmetry? While this is often considered as an
argument against aether, here I provide three independent arguments for why
perturbative unitarity (or weak coupling) of the Lorentz-violating effective
field theories put stringent constraints on possible observable violations of
Lorentz symmetry at high energies. In particular, the interaction with the
scalar graviton in a consistent low-energy theory of gravity and a (radiatively
and dynamically) stable cosmological framework, leads to these constraints. The
violation (quantified by the relative difference in maximum speed of
propagation) is limited to $\lesssim 10^{-10} E({\rm eV})^{-4}$ (superseding
all current empirical bounds), or the theory will be strongly coupled beyond
meV scale. The latter happens in extended Horava-Lifshitz gravities, as a
result of a previously ignored quantum anomaly. Finally, given that all
cosmologically viable theories with significant Lorentz violation appear to be
strongly coupled beyond meV scale, we conjecture that, similar to color
confinement in QCD, or Vainshetin screening for massive gravity, high energy
theories (that interact with gravity) are shielded from Lorentz violation (at
least, up to the scale where gravity is UV-completed). In contrast, microwave
or radio photons, cosmic background neutrinos, or gravitational waves may
provide more promising candidates for discovery of violations of Lorentz
symmetry.",1511.07879v1
2016-09-03,Discussion on Lorentz Invariance Violation of Non-commutative Field Theory and Neutrino Oscillation,"Depending on deformed canonical anti-commutation relations, massless neutrino
oscillation based on Lorentz invariance violation in non-commutative field
theory is discussed. It is found that the previous studies about massless
neutrino oscillation within deformed canonical anti-commutation relations
should satisfy the condition of new Moyal product and new non standard
commutation relations. Furthermore, comparing the Lorentz Invariant Violation
parameters $\mathit{A}$ in the previous studies with new Moyal product and new
non standard commutation relations, we find that the orders of magnitude of
non-commutative parameters (Lorentz invariant Violation parameters
$\mathit{A}$) is not self-consistent. This inconsistency means that the
previous studies of Lorentz invariance violation in non-commutative field
theory may not naturally explain massless neutrino oscillation. In other words,
it should be impossible to explain neutrino oscillation by Lorentz invariance
violation in non-commutative field theory. This conclusion is supported by the
latest atmospheric neutrinos experimental results from the Super-Kamiokande
Collaboration, which show that no evidence of Lorentz invariance violation on
atmospheric neutrinos was observed.",1609.00797v5
2017-03-30,Lorentz Violation and Topologically Trapped Charge Carriers in 2D Materials,"The full spectrum of two-dimensional fermion states in a scalar soliton trap
with a Lorentz breaking background is investigated in the context of the novel
2D materials, where the Lorentz symmetry should not be strictly valid. The
field theoretical model with Lorentz breaking terms represents Dirac electrons
in one valley and in a scalar field background. The Lorentz violation comes
from the difference between the Dirac electron and scalar mode velocities,
which should be expected when modelling the electronic and lattice excitations
in 2D materials. We extend the analytical methods developed in the context of
1+1 field theories to explore the effect of the Lorentz symmetry breaking in
the charge carrier density of 2D materials in the presence of a domain wall
with a kink profile. The width and the depth of the trapping potential from the
kink is controlled by the Lorentz violating term, which is reflected
analytically in the band structure and properties of the trapped states. Our
findings enlarge previous studies of the edge states obtained with domain wall
and in strained graphene nanoribbon in a chiral gauge theory.",1703.10591v1
2013-08-21,Lorentz-violating effects on pair production of W bosons in photon collisions,"We examine Lorentz-violating effects that could appear through deviations of
the Standard Model gauge couplings WWgamma and WWgammagamma. These new physics
effects are explored on the gamma gamma -> WW reaction at the International
Linear Collider. In particular, the associated helicity amplitudes are computed
in the context of the Standard Model Extension (which is a model-independent
approach to CPT and Lorentz violation) and the Effective Lagrangian Model
(which incorporates new physics effects that respect CPT and Lorentz
violation). We perform an exhaustive study of the polarized differential cross
sections to stand out effects related to Lorentz symmetry violation, where it
is evidenced that the effects of Lorentz symmetry violation are more sensitive
to the presence of the b constant background field. We found that for the
$(\pm,\pm,(L,T+T,L))$ polarization state, only Standard Model Extension and
Effective Lagrangian Model contribute at the lowest order, however, both types
of new physics effects are clearly distinguished, being dominant the convoluted
cross section of the Standard Model Extension in around 4 orders of magnitude.
For this polarization state, at the last stage of operation of International
Linear Collider, it is expected an integrated luminosity of 10^3 fb^{-1},
finding around of 2 events for a Lorentz-violating energy scale of 32 TeV.",1308.4664v1
2014-03-18,Equilibria of a charged artificial satellite subject to gravitational and Lorentz torques,"Attitude Dynamics of a rigid artificial satellite subject to gravity gradient
and Lorentz torques in a circular orbit is considered. Lorentz torque is
developed on the basis of the electrodynamic effects of the Lorentz force
acting on the charged satellite's surface. We assume that the satellite is
moving in Low Earth Orbit (LEO) in the geomagnetic field which is considered as
a dipole model. Our model of the torque due to the Lorentz force is developed
for a general shape of artificial satellite, and the nonlinear differential
equations of Euler are used to describe its attitude orientation. All
equilibrium positions are determined and {their} existence conditions are
obtained. The numerical results show that the charge $q$ and radius $\rho_0$ of
the charged center of satellite provide a certain type of semi passive control
for the attitude of satellite. The technique for such kind of control would be
to increase or decrease the electrostatic radiation screening of the satellite.
The results {obtained} confirm that the change in charge can effect the
magnitude of the Lorentz torque, which may affect the satellite's control.
Moreover, the relation between the magnitude of the Lorentz torque and
inclination of the orbits is investigated.",1405.3542v1
2016-12-26,Aspects of fermion dynamics from Lorentz symmetry violation,"In this thesis we are interested in understanding how Lorentz symmetry
violation can affect some features of fermion dynamics and, perhaps, help to
solve some well-known problems in particle physics, such as the origin of
neutrino masses and oscillations.
  Firstly, we consider two Lorentz-Invariance-Violating (LIV) models and
investigate the possibility of generating masses and oscillations dynamically
for both Dirac and Majorana neutrinos, using non-perturbative methods, such as
the Schwinger-Dyson and the effective potential approaches. In our studies,
Lorentz symmetric models are extended by the inclusion of higher-order LIV
operators, which improve the convergence of loop integrals and introduce a
natural mass scale to the theories. We then present how Lorentz invariance can
be recovered, for both models, after quantisation, in such a way that the
dynamical masses and mixing are the only quantum effects that remain finite.
  Additionally, we study how matter fields, especially fermions, behave when
coupled to two modified gravity models. Such modified gravity models break the
4-dimensional diffeomorphism invariance and, consequently, induce local Lorentz
violation. In particular, we consider Horava-Lifshitz gravity, which presents
an improved ultraviolet behaviour when compared to General Relativity (GR), and
thus addresses a fundamental problem in physics: the
non-(perturbative-)renormalisability of the theory of GR. We calculate the LIV
one-loop corrections to the matter sector dispersion relations, after
integration over graviton components, and show that, by imposing reasonable
constraints on the energy scales of our gravity models, our results are
consistent with the current bounds on Lorentz symmetry violation.",1612.08370v1
2019-08-04,Lorentz Breaking and SU(2)_L x U(1)_Y Gauge Invariance for Neutrino Decays,"Conceivable Lorentz-violating effects in the neutrino sector remain a
research area of great general interest, as they touch upon the very
foundations on which the Standard Model and our general understanding of
fundamental interactions is laid. Here, we investigate the relation of Lorentz
violation in the neutrino sector in light of the fact that neutrinos and
corresponding left-handed charged leptons form SU(2)_L doublets under the
electroweak gauge group. Lorentz-violating effects thus cannot be fully
separated from questions related to gauge invariance. The model dependence of
the effective interaction Lagrangians used in various recent investigations is
investigated, with a special emphasis on neutrino splitting, otherwise known as
neutrino-pair Cerenkov radiation, NPCR, and vacuum pair emission
(electron-positron-pair Cerenkov radiation, LPCR). We investigate two scenarios
in which Lorentz violating effects do not necessarily also break electroweak
gauge invarianceThe first of these involves a restricted set of gauge
transformation, a subgroup of SU(2)_L x U(1)_Y, while in the second,
differential Lorentz violation is exclusively introduced by the mixing of the
neutrino flavor and mass eigenstates. Our study culminates in a model which
fully preserves SU(2)_L x U(1)_Y gauge invariance, involves flavor-dependent
Lorentz-breaking parameters, and still allows for NPCR and LPCR decays to
proceed.",1908.01389v2
2020-06-01,Lorentz violating scalar Casimir effect for a $D$-dimensional sphere,"We investigate the Casimir effect, due to the confinement of a scalar field
in a $D$-dimensional sphere, with Lorentz symmetry breaking. The
Lorentz-violating part of the theory is described by the term $\lambda (u \cdot
\partial \phi) ^{2}$, where the parameter $\lambda$ and the background vector
$u^{\mu}$ codify the breakdown of Lorentz symmetry. We compute, as a function
of $D$, the Casimir stress by using Green's function techniques for two
specific choices of the vector $u ^{\mu}$. In the timelike case, $u ^{\mu} =
(1,0,...,0)$, the Casimir stress can be factorized as the product of the
Lorentz invariant result times the factor $(1 + \lambda) ^{-1/2}$. For the
radial spacelike case, $u ^{\mu} = (0,1,0,...,0)$, we obtain an analytical
expression for the Casimir stress which nevertheless does not admit a
factorization in terms of the Lorentz invariant result. For the radial
spacelike case we find that there exists a critical value $\lambda _{c} =
\lambda _{c} (D)$ at which the Casimir stress transits from a repulsive
behavior to an attractive one for any $D> 2$. The physically relevant case $D =
3$ is analyzed in detail where the critical value $\lambda _{c}|_{\small D=3} =
0.0025$ was found. As in the Lorentz symmetric case, the force maintains the
divergent behavior at positive even integer values of $D$.",2006.00696v2
2020-08-27,Bounds on Lorentz-violating Yukawa couplings via lepton electromagnetic moments,"The effective-Lagrangian description of Lorentz-invariance violation provided
by the so-called Standard-Model Extension covers all the sectors of the
Standard Model, allowing for model-independent studies of high-energy phenomena
that might leave traces at relatively-low energies. In this context, the
quantification of the large set of parameters characterizing Lorentz-violating
effects is well motivated. In the present work, effects from the
Lorentz-nonconserving Yukawa sector on the electromagnetic moments of charged
leptons are calculated, estimated, and discussed. Following a perturbative
approach, explicit expressions of leading contributions are derived and upper
bounds on Lorentz violation are estimated from current data on electromagnetic
moments. Scenarios regarding the coefficients of Lorentz violation are
considered. In a scenario of two-point insertions preserving lepton flavor, the
bound on the electron electric dipole moment yields limits as stringent as
$10^{-28}$, whereas muon and tau-lepton electromagnetic moments determine
bounds as restrictive as $10^{-14}$ and $10^{-6}$, respectively. Another
scenario, defined by the assumption that Lorentz-violating Yukawa couplings are
Hermitian, leads to less stringent bounds, provided by the muon anomalous
magnetic moment, which turn out to be as restrictive as $10^{-14}$.",2008.12370v1
2021-11-13,Linear maps preserving the Lorentz spectrum: The $2\times 2$ case,"In this paper a complete description of the linear maps
$\phi:W_{n}\rightarrow W_{n}$ that preserve the Lorentz spectrum is given when
$n=2$ and $W_{n}$ is the space $M_{n}$ of $n\times n$ real matrices or the
subspace $S_{n}$ of $M_{n}$ formed by the symmetric matrices. In both cases, it
has been shown that $\phi(A)=PAP^{-1}$ for all $A\in W_{2}$, where $P$ is a
matrix with a certain structure. It was also shown that such preservers do not
change the nature of the Lorentz eigenvalues (that is, the fact that they are
associated with Lorentz eigenvectors in the interior or on the boundary of the
Lorentz cone). These results extend to $n=2$ those for $n\geq 3$ obtained by
Bueno, Furtado, and Sivakumar (2021). The case $n=2$ has some specificities,
when compared to the case $n\geq3,$ due to the fact that the Lorentz cone in
$\mathbb{R}^{2}$ is polyedral, contrary to what happens when it is contained in
$\mathbb{R}^{n}$ with $n\geq3.$ Thus, the study of the Lorentz spectrum
preservers on $W_n = M_n$ also follows from the known description of the Pareto
spectrum preservers on $M_n$.",2111.07174v2
2022-12-23,Daugavet and diameter two properties in Orlicz-Lorentz spaces,"In this article, we study the diameter two properties (D2Ps), the diametral
diameter two properties (diametral D2Ps), and the Daugavet property in
Orlicz-Lorentz spaces equipped with the Luxemburg norm. First, we characterize
the Radon-Nikod\'ym property of Orlicz-Lorentz spaces in full generality by
considering all finite real-valued Orlicz functions. To show this, the
fundamental functions of their K\""othe dual spaces defined by extended
real-valued Orlicz functions are computed. We also show that if an Orlicz
function does not satisfy the appropriate $\Delta_2$-condition, the
Orlicz-Lorentz space and its order-continuous subspace have the strong diameter
two property. Consequently, given that an Orlicz function is an N-function at
infinity, the same condition characterizes the diameter two properties of
Orlicz-Lorentz spaces as well as the octahedralities of their K\""othe dual
spaces. The Orlicz-Lorentz function spaces with the Daugavet property and the
diametral D2Ps are isometrically isomorphic to $L_1$ when the weight function
is regular. In the process, we observe that every locally uniformly nonsquare
point is not a $\Delta$-point. This fact provides another class of real Banach
spaces without $\Delta$-points. As another application, it is shown that for
Orlicz-Lorentz spaces equipped with the Luxemburg norm defined by an N-function
at infinity, their K\""othe dual spaces do not have the local diameter two
property, and so as other (diametral) diameter two properties and the Daugavet
property.",2212.12149v2
2022-12-26,Jets in a Gamma-Ray Burst During its Prompt Emission: Evolution of Lorentz Factor,"Knowledge about the Lorentz factor and its evolution of relativistic jets in
gamma-ray bursts (GRBs) is crucial to understand their physics. An exact value
of bulk Lorentz factor can be estimated based on a high-energy spectral cutoff,
which may appear in GRBs' prompt emission owing to the absorption of
photon-photon pair production. In this work, we focus on the investigation of
the bulk Lorentz factor evolution of jets in an individual burst. Based on
\textsl{Fermi} observations, we search for the bursts with multiple
$\gamma$-ray pulses characterized by a high-energy spectral cutoff, and nine
GRBs are obtained. Together with the estimation of the pulse duration and
radiation spectrum, the Lorentz factor of jets corresponding to different
pulses in an individual GRB are estimated. It is shown that the Lorentz factor
of jets in an individual GRB fluctuates within a certain range and without a
general trend in these nine GRBs. In addition, the Lorentz factors of the jets
in GRBs~130821A, 160509A and 160625B seem to increase with time. We also study
the relations among $L_{\rm iso }$, $E_{\rm p,z}$, and $\Gamma$ for the pulses
in our sample, which is found to be consistent with that found in previous
works.",2212.13058v1
2023-02-10,Gravitational wave constraints on non-birefringent dispersions of gravitational waves due to Lorentz violations with GWTC-3,"The standard model extension (SME) is an effective field theory framework
that can be used to study the possible violations of Lorentz symmetry in the
gravitational interaction. In the SME's gauge invariant linearized gravity
sector, the dispersion relation of GWs is modified, resulting in anisotropy,
birefringence, and dispersion effects in the propagation of GWs. In this paper,
we mainly focus on the non-birefringent and anisotropic dispersion relation in
the propagation of GWs due to the violation of Lorentz symmetry. With the
modified dispersion relation, we calculate the corresponding modified waveform
of GWs generated by the coalescence of compact binaries. We consider the
effects from the operators with the lowest mass dimension $d=6$ in the gauge
invariant linearized gravity sector of the SME which are expected to have the
dominant Lorentz-violating effect on the propagation of GWs. For this case, the
Lorentz-violating effects are presented by 25 coefficients and we constrain
them independently by the ``maximal-reach"" approach. We use 90 high-confidence
GW events in the GWTC-3 catalog and use {\tt Bilby}, an open source software,
and {\tt Dynest}, a nested sampling package, to perform parameter estimation
with the modified waveform. We do not find any evidence of Lorentz violation in
the GWs data and give a $90\%$ confidence interval for each Lorentz violating
coefficient.",2302.05077v1
2023-02-15,Lorentz transformation of three dimensional gravitational wave tensor,"Recently there are more and more interest on the gravitational wave of moving
sources. This introduces a Lorentz transformation problem of gravitational
wave. Although Bondi-Metzner-Sachs (BMS) theory has in principle already
included the Lorentz transformation of gravitational wave, the transformation
of the three dimensional gravitational wave tensor has not been explicitly
calculated before. Within four dimensional spacetime, gravitational wave have
property of `boost weight zero' and `spin weight 2'. This fact makes the
Lorentz transformation of gravitational wave difficult to understand. In the
current paper we adopt the traditional three dimensional tensor description of
gravitational wave. Such a transverse-traceless tensor describes the
gravitational wave freedom directly. We derive the explicit Lorentz
transformation of the gravitational wave tensor. The transformation is similar
to the Lorentz transformation for electric field vector and magnetic field
vector which are three dimensional vectors. Based on the deduced Lorentz
transformation of the gravitational wave three dimensional tensor, we can
construct the gravitational waveform of moving source with any speed if only
the waveform of the corresponding rest waveform is given. As an example, we
apply our method to the effect of kick velocity of binary black hole. The
adjusted waveform by the kick velocity is presented.",2302.07532v1
2023-12-11,Photospheric Lorentz force changes in eruptive and confined solar flares,"Solar flares are known to leave imprints on the magnetic field at the
photosphere, often manifested as an abrupt and permanent change in the
downward-directed Lorentz force in localized areas inside the active region.
Our study aims to differentiate eruptive and confined solar flares based on the
vertical Lorentz force variations. We select 26 eruptive and 11 confined major
solar flares (stronger than the GOES M5 class) observed during 2011-2017. We
analyze these flaring regions using SHARP vector-magnetograms obtained from the
NASA's Helioseismic and Magnetic Imager (HMI). We also compare data
corresponding to 2 synthetic flares from a $\delta$--sunspot simulation
reported in Chatterjee et al. [Phys. Rev. Lett. 116, 101101 (2016)]. We
estimate the change in the horizontal magnetic field and the total Lorentz
force integrated over an area around the polarity inversion line (PIL) that
encompasses the location of the flare. Our results indicate a rapid increase of
the horizontal magnetic field along the flaring PIL, accompanied by a
significant change in the downward-directed Lorentz force in the same vicinity.
Notably, we find that all the confined events under study exhibit a total
change in Lorentz force of < $1.8 \times 10^{22}$ dyne. This threshold plays an
important factor in effectively distinguishing eruptive and confined flares.
Further, our analysis suggests that the change in total Lorentz force also
depends on the reconnection height in the solar corona during the associated
flare onset. The results provide significant implications for understanding the
flare-related upward impulse transmission for the associated coronal mass
ejection.",2312.06787v1
2023-12-21,New Results in Analysis of Orlicz-Lorentz spaces,"In this article, we investigate the existence of closed vector subspaces
(i.e.spaceability) in various nonlinear subsets of Orlicz-Lorentz spaces
$\Lambda_{\varphi,w}$, equipped with the Luxemburg norm. If a family of Orlicz
functions $(\varphi_n)_{n=1}^{\infty}$ satisfies certain order relations with
respect to a given Orlicz function $\varphi$, the subset of the
order-continuous subspace $(\Lambda_{\varphi,w})_a$ whose elements do not
belong to $\bigcup_{n=1}^{\infty}\Lambda_{\varphi_n,w}$ is spaceable, and even
maximal-spaceable when $\varphi$ satisfies the $\Delta_2$-condition. We also
show that this subset is either residual or empty. In addition, sufficient
conditions for this subset not being $(\alpha, \beta)$-spaceable are provided.
A similar analysis is also performed on the subset $\Lambda_{\varphi,w}
\setminus (\Lambda_{\varphi,w})_a$ when $\varphi$ does not satisfy the
$\Delta_2$-condition.
  The comparison between different Orlicz-Lorentz spaces is characterized via
the generating pairs $(\varphi,w)$. For a fixed Orlicz function that satisfies
the $\Delta_2^{\infty}$-condition, we provide a characterization of disjointly
strictly singular inclusion operators between Orlicz-Lorentz spaces with
different weights. As a consequence, there are certain subsets of
Orlicz-Lorentz spaces on $[0,1]$ for which lineability problem is not valid.
Moreover, various types of $(\alpha,\beta)$-lineability and pointwise
lineability properties on other nonlinear subsets of Orlicz-Lorentz spaces are
examined. These results extend a number of previously known results in Orlicz
and Lorentz spaces.",2312.13903v1
2024-04-07,Tensor gauge fields and dark matter in general relativity with fermions,"The action of general relativity with fermions has two independent
symmetries: general coordinate invariance and local Lorentz invariance. General
coordinate transformations act on coordinates and tensor indices, while local
Lorentz transformations act on Dirac and Lorentz indices, much like a
noncompact internal symmetry. \par The internal-symmetry character of local
Lorentz invariance suggests that it might be implemented by tensor gauge fields
with their own Yang-Mills action rather than by the spin connection as in
standard formulations. But because the Lorentz group is noncompact, their
Yang-Mills action must be modified by a neutral vector field whose average
value at low temperatures is timelike. This vector field and the tensor gauge
fields are neutral and interact gravitationally, so they contribute to hot and
cold dark matter. \par The two independent symmetries of the action are reduced
to a single symmetry of the vacuum, local Lorentz invariance, by the nonzero
average values of the tetrads $c^a_{\phantom{a} k}$. The local Lorentz
invariance of general relativity with fermions can be extended to local U(2,2)
invariance. \par If the contracted squares of the covariant derivatives of the
tetrads multiplied by the square of a mass $M$ are added to the action, then in
the limit $M^2 \to \infty$, the equation of motion of the tensor gauge fields
is the vanishing of the covariant derivatives of the tetrads, which is Cartan's
first equation of structure. In the same limit, the tensor gauge fields
approach the spin connection.",2404.05766v1
1993-06-22,Weakly Damped Modes in Star Clusters and Galaxies,"A perturber may excite a coherent mode in a star cluster or galaxy. If the
stellar system is stable, it is commonly assumed that such a mode will be
strongly damped and therefore of little practical consequence other than
redistributing momentum and energy deposited by the perturber. This paper
demonstrates that this assumption is false; weakly damped modes exist and may
persist long enough to have observable consequences. To do this, a method for
investigating the dispersion relation for spherical stellar systems and for
locating weakly damped modes in particular is developed and applied to King
models of varying concentration. This leads to the following remarkable result:
King models exhibit {\it very} weakly damped $m=1$ modes over a wide range of
concentration ($0.67\le c\le1.5$ have been examined). The predicted damping
time is tens to hundreds of crossing times. This mode causes the peak density
to shift from and slowly revolve about the initial center. The existence of the
mode is supported by n-body simulation. Higher order modes and possible
astronomical consequences are discussed. Weakly damped modes, for example, may
provide a natural explanation for observed discrepancies between density and
kinematic centers in galaxies, the location of velocity cusps due to massive
black holes, and $m=1$ disturbances of disks embedded in massive halos.
Gravitational shocking may excite the $m=1$ mode in globular clusters, which
could modify their subsequent evolution and displace the positions of exotic
remnants.",9306020v1
1997-12-03,On the Evolution of Damped Lyman Alpha Systems to Galactic Disks,"The mean metallicity of the thick disk of the Galaxy is 0.5 dex higher than
that of the damped Lyman alpha systems. This has been interpreted to argue that
stars in the former do not arise out of gas in the latter. Using new
metallicity and H I column-density data we show the metal-rich damped systems
do contain sufficient baryons at the thick-disk metallicity to account for the
stellar masses of thick disks. Comparing our kinematic data with the
metallicities we show that damped Lyman alpha systems exhibiting the largest
profile velocity widths span a narrow range of high metallicities, while
systems with small velocity widths span a wider range of metallicities. This is
naturally explained by passage of the damped Lyman alpha sightlines through
rapidly rotating disks with negative radial gradients in metallicity. The
systematically lower N(H I) of systems with high velocity widths indicates (a)
the gaseous disks have centrally located holes, and (b) an apparent
inconsistency with the protogalactic clump model for damped Lyman alpha
systems. The higher metallicity of systems with low N(H I) further implies that
stars rather than gas dominate the baryonic content of the most metal-rich
damped systems.",9712050v1
1998-10-23,Chemical Abundances of the Damped Lya Systems at z>1.5,"We present chemical abundance measurements for 19 damped lya systems observed
with HIRES on the 10m W.M. Keck Telescope. Our principal goal is to investigate
the abundance patterns of the damped systems and thereby determine the
underlying physical processes which dominate their chemical evolution. We place
particular emphasis on gauging the relative importance of two complementary
effects often invoked to explain the damped lya abundances: (1) nucleosynthetic
enrichment from Type II supernovae and (2) an ISM-like dust depletion pattern.
  Similar to the principal results of Lu et al. (1996), our observations lend
support both for dust depletion and Type II SN enrichment. Specifically, the
observed overabundance of Zn/Fe and underabundance of Ni/Fe relative to solar
abundances suggest significant dust depletion within the damped lya systems.
Meanwhile, the relative abundances of Al, Si, and Cr vs. Fe are consistent with
both dust depletion and Type II supernova enrichment. Our measurements of Ti/Fe
and the Mn/Fe measurements from Lu et al. (1996), however, cannot be explained
by dust depletion and indicate an underlying Type II SN pattern. Finally, the
observed values of [S/Fe] are inconsistent with the combined effects of dust
depletion and the nucleosynthetic yields expected for Type II supernovae. This
last result emphasizes the need for another physical process to explain the
damped lya abundance patterns.
  We also examine the metallicity of the damped lya systems both with respect
to Zn/H and Fe/H. Our results confirm previous surveys by Pettini and
collaborators, i.e., [<Zn/H>] = -1.15 +/- 0.15 dex. [abridged]",9810381v1
2002-04-03,The role of damped Alfven waves on magnetospheric accretion models of young stars,"We examine the role of Alfven wave damping in heating the plasma in the
magnetic funnels of magnetospheric accretion models of young stars. We study
four different damping mechanisms of the Alfven waves: nonlinear, turbulent,
viscous-resistive and collisional. Two different possible origins for the
Alfven waves are discussed: 1) Alfven waves generated at the surface of the
star by the shock produced by the infalling matter; and 2) Alfven waves
generated locally in the funnel by the Kelvin-Helmholtz instability. We find
that, in general, the damping lengths are smaller than the tube length. Since
thermal conduction in the tube is not efficient, Alfven waves generated only at
the star's surface cannot heat the tube to the temperatures necessary to fit
the observations. Only for very low frequency Alfven waves ~10^{-5} the ion
cyclotron frequency, is the viscous-resistive damping length greater than the
tube length. In this case, the Alfven waves produced at the surface of the star
are able to heat the whole tube. Otherwise, local production of Alfven waves is
required to explain the observations. The turbulence level is calculated for
different frequencies for optically thin and thick media. We find that
turbulent velocities varies greatly for different damping mechanisms, reaching
\~100 km s^{-1} for the collisional damping of small frequency waves.",0204056v1
2005-03-24,Fast magnetization switching of Stoner particles: A nonlinear dynamics picture,"The magnetization reversal of Stoner particles is investigated from the point
of view of nonlinear dynamics within the Landau-Lifshitz-Gilbert formulation.
The following results are obtained. 1) We clarify that the so-called
Stoner-Wohlfarth (SW) limit becomes exact when damping constant is infinitely
large. Under the limit, the magnetization moves along the steepest energy
descent path. The minimal switching field is the one at which there is only one
stable fixed point in the system. 2) For a given magnetic anisotropy, there is
a critical value for the damping constant, above which the minimal switching
field is the same as that of the SW-limit. 3) We illustrate how fixed points
and their basins change under a field along different directions. This change
explains well why a non-parallel field gives a smaller minimal switching field
and a short switching time. 4) The field of a ballistic magnetization reversal
should be along certain direction window in the presence of energy dissipation.
The width of the window depends on both of the damping constant and the
magnetic anisotropy. The upper and lower bounds of the direction window
increase with the damping constant. The window width oscillates with the
damping constant for a given magnetic anisotropy. It is zero for both zero and
infinite damping. Thus, the perpendicular field configuration widely employed
in the current experiments is not the best one since the damping constant in a
real system is far from zero.",0503594v1
2009-04-21,Tensor damping in metallic magnetic multilayers,"The mechanism of spin-pumping, described by Tserkovnyak et al., is formally
analyzed in the general case of a magnetic multilayer consisting of two or more
metallic ferromagnetic (FM) films separated by normal metal (NM) layers. It is
shown that the spin-pumping-induced dynamic coupling between FM layers modifies
the linearized Gilbert equations in a way that replaces the scalar Gilbert
damping constant with a nonlocal matrix of Cartesian damping tensors. The
latter are shown to be methodically calculable from a matrix algebra solution
of the Valet-Fert transport equations. As an example, explicit analytical
results are obtained for a 5-layer (spin-valve) of form NM/FM/NM'/FM/NM.
Comparisons with earlier well known results of Tserkovnyak et al. for the
related 3-layer FM/NM/FM indicate that the latter inadvertently hid the tensor
character of the damping, and instead singled out the diagonal element of the
local damping tensor along the axis normal to the plane of the two
magnetization vectors. For spin-valve devices of technological interest, the
influence of the tensor components of the damping on thermal noise or
spin-torque critical currents are strongly weighted by the relative magnitude
of the elements of the nonlocal, anisotropic stiffness-field tensor-matrix, and
for in-plane magnetized spin-valves are generally more sensitive to the
in-plane element of the damping tensor.",0904.3150v2
2009-09-19,Resonantly Damped Kink Magnetohydrodynamic Waves in a Partially Ionized Filament Thread,"Transverse oscillations of solar filament and prominence threads have been
frequently reported. These oscillations have the common features of being of
short period (2-10 min) and being damped after a few periods. Kink
magnetohydrodynamic (MHD) wave modes have been proposed as responsible for the
observed oscillations, whereas resonant absorption in the Alfven continuum and
ion-neutral collisions are the best candidates to be the damping mechanisms.
Here, we study both analytically and numerically the time damping of kink MHD
waves in a cylindrical, partially ionized filament thread embedded in a coronal
environment. The thread model is composed of a straight and thin, homogeneous
filament plasma, with a transverse inhomogeneous transitional layer where the
plasma physical properties vary continuously from filament to coronal
conditions. The magnetic field is homogeneous and parallel to the thread axis.
We find that the kink mode is efficiently damped by resonant absorption for
typical wavelengths of filament oscillations, the damping times being
compatible with the observations. Partial ionization does not affect the
process of resonant absorption, and the filament plasma ionization degree is
only important for the damping for wavelengths much shorter than those
observed. To our knowledge, this is the first time that the phenomenon of
resonant absorption is studied in a partially ionized plasma.",0909.3599v1
2009-10-15,Time damping of non-adiabatic magnetohydrodynamic waves in a partially ionized prominence plasma: Effect of helium,"Prominences are partially ionized, magnetized plasmas embedded in the solar
corona. Damped oscillations and propagating waves are commonly observed. These
oscillations have been interpreted in terms of magnetohydrodynamic (MHD) waves.
Ion-neutral collisions and non-adiabatic effects (radiation losses and thermal
conduction) have been proposed as damping mechanisms. We study the effect of
the presence of helium on the time damping of non-adiabatic MHD waves in a
plasma composed by electrons, protons, neutral hydrogen, neutral helium (He I),
and singly ionized helium (He II) in the single-fluid approximation. The
dispersion relation of linear non-adiabatic MHD waves in a homogeneous,
unbounded, and partially ionized prominence medium is derived. The period and
the damping time of Alfven, slow, fast, and thermal waves are computed. A
parametric study of the ratio of the damping time to the period with respect to
the helium abundance is performed. The efficiency of ion-neutral collisions as
well as thermal conduction is increased by the presence of helium. However, if
realistic abundances of helium in prominences (~10%) are considered, this
effect has a minor influence on the wave damping. The presence of helium can be
safely neglected in studies of MHD waves in partially ionized prominence
plasmas.",0910.2883v1
2010-07-12,Seismology of Standing Kink Oscillations of Solar Prominence Fine Structures,"We investigate standing kink magnetohydrodynamic (MHD) oscillations in a
prominence fine structure modeled as a straight and cylindrical magnetic tube
only partially filled with the prominence material, and with its ends fixed at
two rigid walls representing the solar photosphere. The prominence plasma is
partially ionized and a transverse inhomogeneous transitional layer is included
between the prominence thread and the coronal medium. Thus, ion-neutral
collisions and resonant absorption are the considered damping mechanisms.
Approximate analytical expressions of the period, the damping time, and their
ratio are derived for the fundamental mode in the thin tube and thin boundary
approximations. We find that the dominant damping mechanism is resonant
absorption, which provides damping ratios in agreement with the observations,
whereas ion-neutral collisions are irrelevant for the damping. The values of
the damping ratio are independent of both the prominence thread length and its
position within the magnetic tube, and coincide with the values for a tube
fully filled with the prominence plasma. The implications of our results in the
context of the MHD seismology technique are discussed, pointing out that the
reported short-period (2 - 10 min) and short-wavelength (700 - 8,000 km) thread
oscillations may not be consistent with a standing mode interpretation and
could be related to propagating waves. Finally, we show that the inversion of
some prominence physical parameters, e.g., Alfv\'en speed, magnetic field
strength, transverse inhomogeneity length-scale, etc., is possible using
observationally determined values of the period and damping time of the
oscillations along with the analytical approximations of these quantities.",1007.1959v2
2012-10-30,Mode- and size-dependent Landau-Lifshitz damping in magnetic nanostructures: Evidence for non-local damping,"We demonstrate a strong dependence of the effective damping on the nanomagnet
size and the particular spin-wave mode that can be explained by the theory of
intralayer transverse-spin-pumping. The effective Landau-Lifshitz damping is
measured optically in individual, isolated nanomagnets as small as 100 nm. The
measurements are accomplished by use of a novel heterodyne magneto-optical
microwave microscope with unprecedented sensitivity. Experimental data reveal
multiple standing spin-wave modes that we identify by use of micromagnetic
modeling as having either localized or delocalized character, described
generically as end- and center-modes. The damping parameter of the two modes
depends on both the size of the nanomagnet as well as the particular spin-wave
mode that is excited, with values that are enhanced by as much as 40% relative
to that measured for an extended film. Contrary to expectations based on the ad
hoc consideration of lithography-induced edge damage, the damping for the
end-mode decreases as the size of the nanomagnet decreases. The data agree with
the theory for damping caused by the flow of intralayer transverse
spin-currents driven by the magnetization curvature. These results have serious
implications for the performance of nanoscale spintronic devices such as
spin-torque-transfer magnetic random access memory.",1210.8118v3
2012-11-21,Kinetic theory of surface plasmon polariton in semiconductor nanowires,"Based on the semiclassical model Hamiltonian of the surface plasmon polariton
and the nonequilibrium Green-function approach, we present a microscopic
kinetic theory to study the influence of the electron scattering on the
dynamics of the surface plasmon polariton in semiconductor nanowires. The
damping of the surface plasmon polariton originates from the resonant
absorption by the electrons (Landau damping), and the corresponding damping
exhibits size-dependent oscillations and distinct temperature dependence
without any scattering. The scattering influences the damping by introducing a
broadening and a shifting to the resonance. To demonstrate this, we investigate
the damping of the surface plasmon polariton in InAs nanowires in the presence
of the electron-impurity, electron-phonon and electron-electron Coulomb
scatterings. The main effect of the electron-impurity and electron-phonon
scatterings is to introduce a broadening, whereas the electron-electron Coulomb
scattering can not only cause a broadening, but also introduce a shifting to
the resonance. For InAs nanowires under investigation, the broadening due to
the electron-phonon scattering dominates. As a result, the scattering has a
pronounced influence on the damping of the surface plasmon polariton: The
size-dependent oscillations are smeared out and the temperature dependence is
also suppressed in the presence of the scattering. These results demonstrate
the the important role of the scattering on the surface plasmon polariton
damping in semiconductor nanowires.",1211.5055v2
2013-11-12,Damping filter method for obtaining spatially localized solutions,"Spatially localized structures are key components of turbulence and other
spatio-temporally chaotic systems. From a dynamical systems viewpoint, it is
desirable to obtain corresponding exact solutions, though their existence is
not guaranteed. A damping filter method is introduced to obtain variously
localized solutions, and adopted into two typical cases. This method introduces
a spatially selective damping effect to make a good guess at the exact
solution, and we can obtain an exact solution through a continuation with the
damping amplitude. First target is a steady solution to Swift-Hohenberg
equation, which is a representative of bi-stable systems in which localized
solutions coexist, and a model for span-wisely localized cases. Not only
solutions belonging to the well-known snaking branches but also those belonging
to an isolated branch known as ""isolas"" are found with a continuation paths
between them in phase space extended with the damping amplitude. This indicates
that this spatially selective excitation mechanism has an advantage in
searching spatially localized solutions. Second target is a spatially localized
traveling-wave solution to Kuramoto-Sivashinsky equation, which is a model for
stream-wisely localized cases. Since the spatially selective damping effect
breaks Galilean and translational invariances, the propagation velocity cannot
be determined uniquely while the damping is active, and a singularity arises
when these invariances are recovered. We demonstrate that this singularity can
be avoided by imposing a simple condition, and a localized traveling-wave
solution is obtained with a specific propagation speed.",1311.2792v2
2014-09-19,Highly confined low-loss plasmons in graphene-boron nitride heterostructures,"Graphene plasmons were predicted to possess ultra-strong field confinement
and very low damping at the same time, enabling new classes of devices for deep
subwavelength metamaterials, single-photon nonlinearities, extraordinarily
strong light-matter interactions and nano-optoelectronic switches. While all of
these great prospects require low damping, thus far strong plasmon damping was
observed, with both impurity scattering and many-body effects in graphene
proposed as possible explanations. With the advent of van der Waals
heterostructures, new methods have been developed to integrate graphene with
other atomically flat materials. In this letter we exploit near-field
microscopy to image propagating plasmons in high quality graphene encapsulated
between two films of hexagonal boron nitride (h-BN). We determine dispersion
and particularly plasmon damping in real space. We find unprecedented low
plasmon damping combined with strong field confinement, and identify the main
damping channels as intrinsic thermal phonons in the graphene and dielectric
losses in the h-BN. The observation and in-depth understanding of low plasmon
damping is the key for the development of graphene nano-photonic and
nano-optoelectronic devices.",1409.5674v1
2015-09-02,Energy Dependence of Synchrotron X-Ray Rims in Tycho's Supernova Remnant,"Several young supernova remnants exhibit thin X-ray bright rims of
synchrotron radiation at their forward shocks. Thin rims require strong
magnetic field amplification beyond simple shock compression if rim widths are
only limited by electron energy losses. But, magnetic field damping behind the
shock could produce similarly thin rims with less extreme field amplification.
Variation of rim width with energy may thus discriminate between competing
influences on rim widths. We measured rim widths around Tycho's supernova
remnant in 5 energy bands using an archival 750 ks Chandra observation. Rims
narrow with increasing energy and are well described by either loss-limited or
damped scenarios, so X-ray rim width-energy dependence does not uniquely
specify a model. But, radio counterparts to thin rims are not loss-limited and
better reflect magnetic field structure. Joint radio and X-ray modeling favors
magnetic damping in Tycho's SNR with damping lengths ~1--5% of remnant radius
and magnetic field strengths ~50--400 $\mu$G assuming Bohm diffusion. X-ray rim
widths are ~1% of remnant radius, somewhat smaller than inferred damping
lengths. Electron energy losses are important in all models of X-ray rims,
suggesting that the distinction between loss-limited and damped models is
blurred in soft X-rays. All loss-limited and damping models require magnetic
fields $\gtrsim$ 20 $\mu$G, affirming the necessity of magnetic field
amplification beyond simple compression.",1509.00877v1
2016-02-02,Forward Modelling of Propagating Slow Waves in Coronal Loops and Their Frequency-Dependent Damping,"Propagating slow waves in coronal loops exhibit a damping which depends upon
the frequency of the waves. In this study we aim to investigate the
relationship of the damping length (L$_d$) with the frequency of the
propagating wave. We present a 3-D coronal loop model with uniform density and
temperature and investigate the frequency dependent damping mechanism for the
four chosen wave periods. We include the thermal conduction to damp the waves
as they propagate through the loop. The numerical model output has been forward
modelled to generate synthetic images of SDO/AIA 171 \r{A} and 193 \r{A}
channels. The use of forward modelling, which incorporates the atomic emission
properties into the intensity images, allows us to directly compare our results
with the real observations. The results show that the damping lengths vary
linearly with the periods. We also measure the contributions of the emission
properties on the damping lengths by using density values from the simulation.
In addition to that} we have also calculated the theoretical dependence of
L$_d$ with wave periods and showed that it is consistent with the results we
obtained from the numerical modelling and earlier observations.",1602.00787v1
2017-08-16,Damping of an oscillating scalar field indirectly coupled to a thermal bath,"The damping process of a homogeneous oscillating scalar field that indirectly
interacts with a thermal bath through a mediator field is investigated over a
wide range of model parameters. We consider two types of mediator fields, those
that can decay to the thermal bath and those that are individually stable but
pair annihilate. The former case has been extensively studied in the literature
by treating the damping as a local effect after integrating out the assumed
close-to-equilibrium mediator field. The same approach does not apply if the
mediator field is stable and freezes out of equilibrium. To account for the
latter case, we adopt a non-local description of damping that is only
meaningful when we consider full half-oscillations of the field being damped.
The damping rates of the oscillating scalar field and the corresponding heating
rate of the thermal bath in all bulk parameter regions are calculated in both
cases, corroborating previous results in the direct decay case. Using the
obtained results, the time it takes for the amplitude of the scalar field to be
substantially damped is estimated.",1708.04865v2
2018-04-20,A Weakly Nonlinear Model for the Damping of Resonantly Forced Density Waves in Dense Planetary Rings,"In this paper we address the stability of resonantly forced density waves in
dense planetary rings.
  Already by Goldreich & Tremaine (1978) it has been argued that density waves
might be unstable, depending on the relationship between the ring's viscosity
and the surface mass density.
  In the recent paper Schmidt et al. (2016) we have pointed out that when -
within a fluid description of the ring dynamics - the criterion for viscous
overstability is satisfied, forced spiral density waves become unstable as
well.
  In this case, linear theory fails to describe the damping, but nonlinearity
of the underlying equations guarantees a finite amplitude and eventually a
damping of the wave.
  We apply the multiple scale formalism to derive a weakly nonlinear damping
relation from a hydrodynamical model.
  This relation describes the resonant excitation and nonlinear viscous damping
of spiral density waves in a vertically integrated fluid disk with density
dependent transport coefficients.
  The model consistently predicts density waves to be (linearly) unstable in a
ring region where the conditions for viscous overstability are met.
  Sufficiently far away from the Lindblad resonance, the surface mass density
perturbation is predicted to saturate to a constant value due to nonlinear
viscous damping.
  The wave's damping lengths of the model depend on certain input parameters,
such as the distance to the threshold for viscous overstability in parameter
space and the ground state surface mass density.",1804.07674v1
2020-07-07,Nonlinear viscoelastic isolation for seismic vibration mitigation,"The aim of this paper is to assess the effectiveness of nonlinear
viscoelastic damping in controlling base-excited vibrations. Specifically, the
focus is on investigating the robustness of the nonlinear base isolation
performance in controlling the system response due to a wide set of possible
excitation spectra. The dynamic model is derived to study a simple structure
whose base isolation is provided via a Rubber-Layer Roller Bearing (RLRB)
(rigid cylinders rolling on rigid plates with highly damping rubber coatings)
equipped with a nonlinear cubic spring, thus presenting both nonlinear damping
and stiffness. We found that, under periodic loading, due to the non-monotonic
bell-shaped viscoelastic damping arising from the viscoelastic rolling
contacts, different dynamic regimes occur mostly depending on whether the
damping peak is overcome or not. Interestingly, in the former case, poorly
damped self-excited vibrations may be triggered by the steep damping decrease.
Moreover, in order to investigate the robustness of the isolation performance,
we consider a set of real seismic excitations, showing that tuned nonlinear
RLRB provide loads isolation in a wider range of excitation spectra, compared
to generic linear isolators. This is peculiarly suited for applications (such
as seismic and failure engineering) in which the specific excitation spectrum
is unknown a priori, and blind design on statistical data has to be employed.",2007.04378v1
2016-11-17,Inductive detection of field-like and damping-like AC inverse spin-orbit torques in ferromagnet/normal metal bilayers,"Functional spintronic devices rely on spin-charge interconversion effects,
such as the reciprocal processes of electric field-driven spin torque and
magnetization dynamics-driven spin and charge flow. Both damping-like and
field-like spin-orbit torques have been observed in the forward process of
current-driven spin torque and damping-like inverse spin-orbit torque has been
well-studied via spin pumping into heavy metal layers. Here we demonstrate that
established microwave transmission spectroscopy of ferromagnet/normal metal
bilayers under ferromagnetic resonance can be used to inductively detect the AC
charge currents driven by the inverse spin-charge conversion processes. This
technique relies on vector network analyzer ferromagnetic resonance (VNA-FMR)
measurements. We show that in addition to the commonly-extracted spectroscopic
information, VNA-FMR measurements can be used to quantify the magnitude and
phase of all AC charge currents in the sample, including those due to spin
pumping and spin-charge conversion. Our findings reveal that
Ni$_{80}$Fe$_{20}$/Pt bilayers exhibit both damping-like and field-like inverse
spin-orbit torques. While the magnitudes of both the damping-like and
field-like inverse spin-orbit torque are of comparable scale to prior reported
values for similar material systems, we observed a significant dependence of
the damping-like magnitude on the order of deposition. This suggests interface
quality plays an important role in the overall strength of the damping-like
spin-to-charge conversion.",1611.05798v2
2017-01-04,Controlling plasmon modes and damping in buckled two-dimensional material open systems,"Full ranges of both hybrid plasmon-mode dispersions and their damping are
studied systematically by our recently developed mean-field theory in open
systems involving a conducting substrate and a two-dimensional (2D) material
with a buckled honeycomb lattice, such as silicene, germanene, and a group
\rom{4} dichalcogenide as well. In this hybrid system, the single plasmon mode
for a free-standing 2D layer is split into one acoustic-like and one
optical-like mode, leading to a dramatic change in the damping of plasmon
modes. In comparison with gapped graphene, critical features associated with
plasmon modes and damping in silicene and molybdenum disulfide are found with
various spin-orbit and lattice asymmetry energy bandgaps, doping types and
levels, and coupling strengths between 2D materials and the conducting
substrate. The obtained damping dependence on both spin and valley degrees of
freedom is expected to facilitate measuring the open-system dielectric property
and the spin-orbit coupling strength of individual 2D materials. The unique
linear dispersion of the acoustic-like plasmon mode introduces additional
damping from the intraband particle-hole modes which is absent for a
free-standing 2D material layer, and the use of molybdenum disulfide with a
large bandgap simultaneously suppresses the strong damping from the interband
particle-hole modes.",1701.01084v1
2017-04-05,Stimulated Brillouin scattering behaviors in different species ignition hohlraum plasmas in high-temperature and high-density region,"The presence of multiple ion species can add additional branches to the IAW
dispersion relation and change the Landau damping significantly. Different IAW
modes excited by stimulated Brillouin scattering (SBS) and different SBS
behaviors in several typical ignition hohlraum plasmas in the high-temperature
and high-density region have been researched by Vlasov-Maxwell simulation. The
slow mode in HeH or CH plasmas is the least damped mode and will be excited in
SBS, while the fast mode in AuB plasmas is the least damped mode and will be
excited in SBS. Due to strong Landau damping, the SBS in H or HeH plasmas is
strong convective instability, while the SBS in AuB plasmas is absolute
instability due to the weak Landau damping. However, although the SBS in CH
plasmas is weak convective instability in the linear theory, the SBS will
transform into absolute instability due to decreasing linear Landau damping by
particles trapping. These results give a detail research of the IAW modes
excitation and the properties of SBS in different species plasmas, thus
providing the possibility of controlling SBS by increasing the linear Landau
damping of the IAW by changing ion species.",1704.02317v1
2009-12-21,The effect of longitudinal flow on resonantly damped kink oscillations,"The most promising mechanism acting towards damping the kink oscillations of
coronal loops is resonant absorption. In this context most of previous studies
neglected the effect of the obvious equilibrium flow along magnetic field
lines. The flows are in general sub-Alfv\'enic and hence comparatively slow.
Here we investigate the effect of an equilibrium flow on the resonant
absorption of linear kink MHD waves in a cylindrical magnetic flux tube with
the aim of determining the changes in the frequency of the forward and backward
propagating waves and in the modification of the damping times due to the flow.
A loop model with both the density and the longitudinal flow changing in the
radial direction is considered. We use the thin tube thin boundary (TTTB)
approximation in order to calculate the damping rates. The full resistive
eigenvalue problem is also solved without assuming the TTTB approximation.
Using the small ratio of flow and Alfv\'en speeds we derive simple analytical
expressions to the damping rate. The analytical expressions are in good
agreement with the resistive eigenmode calculations. Under typical coronal
conditions the effect of the flow on the damped kink oscillations is small when
the characteristic scale of the density layer is similar or smaller than the
characteristic width of the velocity layer. However, in the opposite situation
the damping rates can be significantly altered, specially for the backward
propagating wave which is undamped while the forward wave is overdamped.",0912.4136v1
2016-05-11,Damping of prominence longitudinal oscillations due to mass accretion,"We study the damping of longitudinal oscillations of a prominence thread
caused by the mass accretion. In this model we considered a thin curved
magnetic tube filled with the plasma. The parts of the tube at the two sides of
the thread are filled with hot rarefied plasma. We assume that there are flows
of rarefied plasma toward the thread caused by the plasma evaporation at the
magnetic tube footpoints. Our main assumption is that the hot plasma is
instantaneously accommodated by the thread when it arrives at the thread, and
its temperature and density become equal to those of the thread. Then we derive
the system of ordinary differential equations describing the thread dynamics.
We consider linear and nonlinear oscillation. The nonlinearity reduces the
damping time, however this reduction is small. The damping time is inversely
proportional to the accretion rate. We also obtain that the oscillation periods
decrease with time. However even for the largest initial oscillation amplitude
considered in our article the period reduction does not exceed 20%. We conclude
that the mass accretion can damp the motion of the threads rapidly. Thus, this
mechanism can explain the observed strong damping of large-amplitude
longitudinal oscillations. In addition, the damping time can be used to
determine the mass accretion rate and indirectly the coronal heating.",1605.03376v1
2016-12-30,Spectroscopic evidence of Alfvén wave damping in the off-limb solar corona,"We investigate off-limb active region and quiet Sun corona using
spectroscopic data. Active region is clearly visible in several spectral lines
formed in the temperature range of 1.1--2.8 MK. We derive electron number
density using line ratio method, and non-thermal velocity in the off-limb
region up to the distance of 140 Mm. We compare density scale heights derived
from several spectral line pairs with expected scale heights as per hydrostatic
equilibrium model. Using several isolated and unblended spectral line profiles,
we estimate non-thermal velocities in active region and quiet Sun. Non-thermal
velocities obtained from warm lines in active region first show increase and
later show either decrease or almost constant value with height in the far
off-limb region, whereas hot lines show consistent decrease. However, in the
quiet Sun region, non-thermal velocities obtained from various spectral lines
show either gradual decrease or remain almost constant with height. Using these
obtained parameters, we further calculate Alfv\'en wave energy flux in the both
active and quiet Sun regions. We find significant decrease in wave energy
fluxes with height, and hence provide evidence of Alfv\'en wave damping.
Furthermore, we derive damping lengths of Alfv\'en waves in the both regions
and find them to be in the range of 25-170 Mm. Different damping lengths
obtained at different temperatures may be explained as either possible
temperature dependent damping or measurements obtained in different coronal
structures formed at different temperatures along the line-of-sight.
Temperature dependent damping may suggest some role of thermal conduction in
the damping of Alfv\'en waves in the lower corona.",1612.09551v2
2017-06-29,Resonant Absorption of Axisymmetric Modes in Twisted Magnetic Flux Tubes,"It has been shown recently that magnetic twist and axisymmetric MHD modes are
ubiquitous in the solar atmosphere and therefore, the study of resonant
absorption for these modes have become a pressing issue as it can have
important consequences for heating magnetic flux tubes in the solar atmosphere
and the observed damping. In this investigation, for the first time, we
calculate the damping rate for axisymmetric MHD waves in weakly twisted
magnetic flux tubes. Our aim is to investigate the impact of resonant damping
of these modes for solar atmospheric conditions. This analytical study is based
on an idealized configuration of a straight magnetic flux tube with a weak
magnetic twist inside as well as outside the tube. By implementing the
conservation laws derived by \cite{Sakurai:1991aa} and the analytic solutions
for weakly twisted flux tubes obtained recently by \cite{Giagkiozis:2015apj},
we derive a dispersion relation for resonantly damped axisymmetric modes in the
spectrum of the Alfv\'{e}n continuum. We also obtain an insightful analytical
expression for the damping rate in the long wavelength limit. Furthermore, it
shown that both the longitudinal magnetic field and the density, which are
allowed to vary continuously in the inhomogeneous layer, have a significant
impact on the damping time. Given the conditions in the solar atmosphere,
resonantly damped axisymmetric modes are highly likely to be ubiquitous and
play an important role in energy dissipation.
  We also suggest that given the character of these waves, it is likely that
they have already been observed in the guise of Alfv\'{e}n waves.",1706.09665v1
2018-09-14,Continuous and discrete damping reduction for systems with quadratic interaction,"We study the connection between Lagrangian and Hamiltonian descriptions of
closed/open dynamics, for a collection of particles with quadratic interaction
(closed system) and a sub-collection of particles with linear damping (open
system). We consider both continuous and discrete versions of mechanics. We
define the Damping Reduction as the mapping from the equations of motion of the
closed system to those of the open one. As variational instruments for the
obtention of these equations we use the Hamilton's principle (closed dynamics)
and Lagrange-d'Alembert principle (open dynamics). We establish the
commutativity of the branches Legendre transform + Damping Reduction and
Damping Reduction+Legendre transform, where the Legendre transform is the usual
mapping between Lagrangian and Hamiltonian mechanics. At a discrete level, this
commutativity provides interesting insight about the resulting integrators.
More concretely, Discrete Damping Reduction yields particular numerical schemes
for linearly damped systems which are not symplectic anymore, but preserve some
of the features of their symplectic counterparts from which they proceed (for
instance the semi-implicitness in some cases). The theoretical results are
illustrated with the examples of the heat bath and transmission lines. In the
latter case some simulations are displayed, showing a better performance of the
integrators with variational origin.",1809.05532v1
2021-01-20,Damped perturbations in stellar systems: Genuine modes and Landau-damped waves,"This research was stimulated by the recent studies of damping solutions in
dynamically stable spherical stellar systems. Using the simplest model of the
homogeneous stellar medium, we discuss nontrivial features of stellar systems.
Taking them into account will make it possible to correctly interpret the
results obtained earlier and will help to set up decisive numerical experiments
in the future. In particular, we compare the initial value problem versus the
eigenvalue problem. It turns out that in the unstable regime, the Landau-damped
waves can be represented as a superposition of van Kampen modes {\it plus} a
discrete damped mode, usually ignored in the stability study. This mode is a
solution complex conjugate to the unstable Jeans mode. In contrast, the
Landau-damped waves are not genuine modes: in modes, eigenfunctions depend on
time as $\exp (-{\rm i} \omega t)$, while the waves do not have eigenfunctions
on the real $v$-axis at all. However, `eigenfunctions' on the complex
$v$-contours do exist. Deviations from the Landau damping are common and can be
due to singularities or cut-off of the initial perturbation above some fixed
value in the velocity space.",2101.08287v2
2019-03-02,Complex Stiffness Model of Physical Human-Robot Interaction: Implications for Control of Performance Augmentation Exoskeletons,"Human joint dynamic stiffness plays an important role in the stability of
performance augmentation exoskeletons. In this paper, we consider a new
frequency domain model of the human joint dynamics which features a complex
value stiffness. This complex stiffness consists of a real stiffness and a
hysteretic damping. We use it to explain the dynamic behaviors of the human
connected to the exoskeleton, in particular the observed non-zero low frequency
phase shift and the near constant damping ratio of the resonant as stiffness
and inertia vary. We validate this concept by experimenting with an elbow-joint
exoskeleton testbed on a subject while modifying joint stiffness behavior,
exoskeleton inertia, and strength augmentation gains. We compare three
different models of elbow-joint dynamic stiffness: a model with real stiffness,
viscous damping and inertia, a model with complex stiffness and inertia, and a
model combining the previous two models. Our results show that the hysteretic
damping term improves modeling accuracy, using a statistical F-test. Moreover
this improvement is statistically more significant than using classical viscous
damping term. In addition, we experimentally observe a linear relationship
between the hysteretic damping and the real part of the stiffness which allows
us to simplify the complex stiffness model as a 1-parameter system. Ultimately,
we design a fractional order controller to demonstrate how human hysteretic
damping behavior can be exploited to improve strength amplification performance
while maintaining stability.",1903.00704v4
2020-05-31,Optimal decay rates of the compressible Euler equations with time-dependent damping in $\mathbb R^n$: (II) over-damping case,"This paper is concerned with the multi-dimensional compressible Euler
equations with time-dependent over-damping of the form
$-\frac{\mu}{(1+t)^\lambda}\rho\boldsymbol u$ in $\mathbb R^n$, where $n\ge2$,
$\mu>0$, and $\lambda\in[-1,0)$. This continues our previous work dealing with
the under-damping case for $\lambda\in[0,1)$. We show the optimal decay
estimates of the solutions such that for $\lambda\in(-1,0)$ and $n\ge2$,
$\|\rho-1\|_{L^2(\mathbb R^n)}\approx(1+t)^{-\frac{1+\lambda}{4}n}$ and
$\|\boldsymbol u\|_{L^2(\mathbb R^n)}\approx
(1+t)^{-\frac{1+\lambda}{4}n-\frac{1-\lambda}{2}}$, which indicates that a
stronger damping gives rise to solutions decaying optimally slower. For the
critical case of $\lambda=-1$, we prove the optimal logarithmical decay of the
perturbation of density for the damped Euler equations such that
$\|\rho-1\|_{L^2(\mathbb R^n)}\approx |\ln(e+t)|^{-\frac{n}{4}}$ and
$\|\boldsymbol u\|_{L^2(\mathbb R^n)}\approx
(1+t)^{-1}\cdot|\ln(e+t)|^{-\frac{n}{4}-\frac{1}{2}}$ for $n\ge7$. The
over-damping effect reduces the decay rates of the solutions to be slow, which
causes us some technical difficulty in obtaining the optimal decay rates by the
Fourier analysis method and the Green function method. Here, we propose a new
idea to overcome such a difficulty by artfully combining the Green function
method and the time-weighted energy method.",2006.00403v1
2021-03-10,Dynamical Pose Estimation,"We study the problem of aligning two sets of 3D geometric primitives given
known correspondences. Our first contribution is to show that this primitive
alignment framework unifies five perception problems including point cloud
registration, primitive (mesh) registration, category-level 3D registration,
absolution pose estimation (APE), and category-level APE. Our second
contribution is to propose DynAMical Pose estimation (DAMP), the first general
and practical algorithm to solve primitive alignment problem by simulating
rigid body dynamics arising from virtual springs and damping, where the springs
span the shortest distances between corresponding primitives. We evaluate DAMP
in simulated and real datasets across all five problems, and demonstrate (i)
DAMP always converges to the globally optimal solution in the first three
problems with 3D-3D correspondences; (ii) although DAMP sometimes converges to
suboptimal solutions in the last two problems with 2D-3D correspondences, using
a scheme for escaping local minima, DAMP always succeeds. Our third
contribution is to demystify the surprising empirical performance of DAMP and
formally prove a global convergence result in the case of point cloud
registration by charactering local stability of the equilibrium points of the
underlying dynamical system.",2103.06182v3
2021-04-13,Apparent nonlinear damping triggered by quantum fluctuations,"Nonlinear damping, the change in damping rate with the amplitude of
oscillations plays an important role in many electrical, mechanical and even
biological oscillators. In novel technologies such as carbon nanotubes,
graphene membranes or superconducting resonators, the origin of nonlinear
damping is sometimes unclear. This presents a problem, as the damping rate is a
key figure of merit in the application of these systems to extremely precise
sensors or quantum computers. Through measurements of a superconducting
resonator, we show that from the interplay of quantum fluctuations and the
nonlinearity of a Josephson junction emerges a power-dependence in the
resonator response which closely resembles nonlinear damping. The phenomenon
can be understood and visualized through the flow of quasi-probability in phase
space where it reveals itself as dephasing. Crucially, the effect is not
restricted to superconducting circuits: we expect that quantum fluctuations or
other sources of noise give rise to apparent nonlinear damping in systems with
a similar conservative nonlinearity, such as nano-mechanical oscillators or
even macroscopic systems.",2104.06464v2
2023-07-26,Improving frequency response with synthetic damping available from fleets of distributed energy resources,"With the increasing use of renewable generation in power systems, responsive
resources will be necessary to support primary frequency control in future
low-inertia/under-damped power systems. Flexible loads can provide
fast-frequency response services if coordinated effectively. However, practical
implementations of such synthetic damping services require both effective local
sensing and control at the device level and an ability to accurately estimate
online and predict the available synthetic damping from a fleet. In addition,
the inherent trade-off between a fleet being available for fast frequency
response while providing other ancillary services needs to be characterized. In
this context, the manuscript presents a novel, fully decentralized,
packet-based controller for diverse flexible loads that dynamically prioritizes
and interrupts loads to engender synthetic damping suitable for primary
frequency control. Moreover, the packet-based control methodology is shown to
accurately characterize the available synthetic damping in real-time, which is
useful to aggregators and system operators. Furthermore, spectral analysis of
historical frequency regulation data is used to produce a probabilistic bound
on the expected available synthetic damping for primary frequency control from
a fleet and the trade-off from concurrently providing secondary frequency
control services. Finally, numerical simulation on IEEE test networks
demonstrates the effectiveness of the proposed methodology.",2307.14498v1
2023-12-11,Possible Contamination of the Intergalactic Medium Damping Wing in ULAS J1342+0928 by Proximate Damped Ly$α$ Absorption,"The red damping wing from neutral hydrogen in the intergalactic medium is a
smoking-gun signal of ongoing reionization. One potential contaminant of the
intergalactic damping wing signal is dense gas associated with foreground
galaxies, which can give rise to proximate damped Ly$\alpha$ absorbers. The
Ly$\alpha$ imprint of such absorbers on background quasars is indistinguishable
from the intergalactic medium within the uncertainty of the intrinsic quasar
continuum, and their abundance at $z\gtrsim7$ is unknown. Here we show that the
complex of low-ionization metal absorption systems recently discovered by deep
JWST/NIRSpec observations in the foreground of the $z=7.54$ quasar
ULAS~J1342$+$0928 can potentially reproduce the quasar's spectral profile close
to rest-frame Ly$\alpha$ without invoking a substantial contribution from the
intergalactic medium, but only if the absorbing gas is extremely metal-poor
($[{\rm O}/{\rm H}]\sim-3.5$). Such a low oxygen abundance has never been
observed in a damped Ly$\alpha$ absorber at any redshift, but this possibility
still complicates the interpretation of the spectrum. Our analysis highlights
the need for deep spectroscopy of high-redshift quasars with JWST or ELT to
""purify"" damping wing quasar samples, an exercise which is impossible for much
fainter objects like galaxies.",2312.06747v1
2023-12-20,An effective field theory of damped ferromagnetic systems,"Using the in-in formalism, we generalize the recently constructed
magnetoelastic EFT arXiv:2112.13873 [hep-th] to describe the damping dynamics
of ferromagnetic systems at long wavelengths. We find that the standard Gilbert
damping term naturally arises as the simplest leading-order symmetry-consistent
non-conservative contribution within the in-in framework. The EFT is easily
generalized to scenarios with anisotropy and inhomogeneity. In particular, we
find the classic Landau-Lifshitz damping term emerges when isotropy is broken
by a constant external background field. This provides a first principle
explanation for distinguishing the two types of damping dynamics that were
originally constructed phenomenologically. Furthermore, the EFT framework could
also incorporate intrinsic anisotropy of the material in a straightforward way
using the spurion method. For systems with inhomogeneity such as nontrivial
spin textures, we find that the leading order derivative correction yields the
generalized Gilbert damping equations that were found in condensed matter
literature. This shows that the EFT approach enables us to derive the form of
higher-derivative-order corrections in a systematic way. Lastly, using the
phonon-magnon coupling deduced in the magnetoelastic EFT, we are able to make a
prediction for the generic form of the phononic contribution to the damping
equation.",2312.13093v1
2024-03-13,Thermal Hall effect incorporating magnon damping in localized spin systems,"We propose a theory for thermal Hall transport mediated by magnons to address
the impact of their damping resulting from magnon-magnon interactions in
insulating magnets. This phenomenon is anticipated to be particularly
significant in systems characterized by strong quantum fluctuations,
exemplified by spin-1/2 systems. Employing a nonlinear flavor-wave theory, we
analyze a general model for localized electron systems and develop a
formulation for thermal conductivity based on a perturbation theory, utilizing
bosonic Green's functions with a nonzero self-energy. We derive the expression
of the thermal Hall conductivity incorporating magnon damping. To demonstrate
the applicability of the obtained representation, we adopt it to two $S=1/2$
quantum spin models on a honeycomb lattice. In calculations for these systems,
we make use of the self-consistent imaginary Dyson equation approach at finite
temperatures for evaluating the magnon damping rate. In both systems, the
thermal Hall conductivity is diminished due to the introduction of magnon
damping over a wide temperature range. This effect arises due to the smearing
of magnon spectra with nonzero Berry curvatures. We also discuss the relation
to the damping of chiral edge modes of magnons. Our formulation can be applied
to various localized electron systems as we begin with a general Hamiltonian
for these systems. Our findings shed light on a new aspect of topological
magnonics emergent from many-body effects and will stimulate further
investigations on the impact of magnon damping on topological phenomena.",2403.08478v1
2024-04-02,A recipe for eccentricity and inclination damping for partial gap opening planets in 3D disks,"In a previous paper we showed that, like the migration speed, the
eccentricity damping efficiency is modulated linearly by the depth of the
partial gap a planet carves in the disk surface density profile, resulting in
less efficient $e$-damping compared to the prescription commonly used in
population synthesis works. Here, we extend our analysis to 3D, refining our
$e$-damping formula and studying how the inclination damping efficiency is also
affected. We perform high resolution 3D locally isothermal hydrodynamical
simulations of planets with varying masses embedded in disks with varying
aspect ratios and viscosities. We extract the gap profile and orbital damping
timescales for fixed eccentricities and inclinations up to the disk scale
height. The limit in gap depths below which vortices appear, in the
low-viscosity case, happens roughly at the transition between classical type-I
and type-II migration regimes. The orbital damping timescales can be described
by two linear trends with a break around gap depths $\sim80\%$ and with slopes
and intercepts depending on the eccentricity and inclination. These trends are
understood on physical grounds and are reproduced by simple fitting formulas
whose error is within the typically uncertainty of type-I torque formulas.
Thus, our recipes for the gap depth and orbital damping efficiencies yield a
simple description for planet-disk interactions to use in N-body codes in the
case of partial gap opening planets that is consistent with high-resolution 3D
hydro-simulations. Finally, we show examples of how our novel orbital damping
prescription can affect the outcome of population synthesis experiments.",2404.02247v1
2015-05-11,Search for anisotropic Lorentz invariance violation with γ-rays,"While Lorentz invariance, the fundamental symmetry of Einstein's theory of
General Relativity, has been tested to a great level of detail, Grand Unified
Theories that combine gravity with the other three fundamental forces may
result in a violation of Lorentz symmetry at the Planck scale. These energies
are unattainable experimentally. However, minute deviations from Lorentz
invariance may still be present at much lower energies. These deviations can
accumulate over large distances, making astrophysical measurements the most
sensitive tests of Lorentz symmetry. One effect of Lorentz invariance violation
is an energy dependent photon dispersion of the vacuum resulting in differences
of the light travel time from distant objects. The Standard-Model Extension
(SME) is an effective theory to describe the low-energy behavior of a more
fundamental Grand Unified Theory, including Lorentz and CPT violating terms. In
the SME the Lorentz violating operators can in part be classified by their
mass-dimension d, with the lowest order being d=5. However, measurements of
photon polarization have constrained operators with d=5 setting lower limits on
the energy at which they become dominant well beyond the Planck scale. On the
other hand, these operators also violate CPT, and thus d=6 could be the leading
order. In this paper we present constraints on all 25 real coefficients
describing anisotropic non-birefringent Lorentz invariance violation at mass
dimension d=6 in the SME. We used Fermi-LAT observations of 25 active galactic
nuclei to constrain photon dispersion and combined our results with previously
published limits in order to simultaneously constrain all 25 coefficients. This
represents the first set of constraints on these coefficients of a
mass-dimension d=6, whereas previous measurements were only able to constrain
linear combinations of all 25 coefficients.",1505.02669v2
2020-10-21,On Lorentz invariant complex scalar fields,"We obtain a Lorentz covariant wave equation whose complex wave function
transforms under a Lorentz boost according to the following rule,
$\Psi(x)\rightarrow e^{\frac{i}{\hbar}f(x)}\Psi(x)$. We show that the spacetime
dependent phase $f(x)$ is the most natural relativistic extension of the phase
associated with the transformation rule for the non-relativistic Schroedinger
wave function when it is subjected to a Galilean transformation. We then
generalize the previous analysis by postulating that $\Psi(x)$ transforms
according to the above rule under proper Lorentz transformations (boosts or
spatial rotations). This is the most general transformation rule compatible
with a Lorentz invariant physical theory whose observables are bilinear
functions of the field $\Psi(x)$. We use the previous wave equations to
describe several physical systems. In particular, we solve the bound state and
scattering problems of two particles which interact both electromagnetically
and gravitationally (static electromagnetic and gravitational fields). The
former interaction is modeled via the minimal coupling prescription while the
latter enters via an external potential. We also formulate logically consistent
classical and quantum field theories associated with these Lorentz covariant
wave equations. We show that it is possible to make those theories equivalent
to the Klein-Gordon theory whenever we have self-interacting terms that do not
break their Lorentz invariance or if we introduce electromagnetic interactions
via the minimal coupling prescription. For interactions that break Lorentz
invariance, we show that the present theories imply that particles and
antiparticles behave differently at decaying processes, with the latter being
more unstable. This suggests a possible connection between Lorentz
invariance-breaking interactions and the matter-antimatter asymmetry problem.",2010.13767v3
2000-12-18,Statistical properties of inelastic Lorentz gas,"The inelastic Lorentz gas in cooling states is studied. It is found that the
inelastic Lorentz gas is localized and that the mean square displacement of the
inelastic Lorentz gas obeys a power of a logarithmic function of time. It is
also found that the scaled position distribution of the inelastic Lorentz gas
has an exponential tail, while the distribution is close to the Gaussian near
the peak. Using a random walk model, we derive an analytical expression of the
mean square displacement as a function of time and the restitution coefficient,
which well agrees with the data of our simulation. The exponential tail of the
scaled position distribution function is also obtained by the method of
steepest descent.",0012325v3
1999-12-29,Proposed astrophysical test of Lorentz invariance,"Working in the context of a Lorentz-violating extension of the standard model
we show that estimates of Lorentz symmetry violation extracted from ultra-high
energy cosmic rays beyond the Greisen-Kuzmin-Zatsepin (GZK) cutoff allow for
setting bounds on parameters of that extension. Furthermore, we argue that a
correlated measurement of the difference in the arrival time of gamma-ray
photons and neutrinos emitted from active galactic nuclei or gamma-ray bursts
may provide a signature of possible violation of Lorentz symmetry. We have
found that this time delay is energy independent, however it has a dependence
on the chirality of the particles involved. We also briefly discuss the known
settings where the mechanism for spontaneous violation of Lorentz symmetry in
the context of string/M-theory may take place.",9912117v2
2002-01-28,Hilbert space structure of covariant loop quantum gravity,"We investigate the Hilbert space in the Lorentz covariant approach to loop
quantum gravity. We restrict ourselves to the space where all area operators
are simultaneously diagonalizable, assuming that it exists. In this sector
quantum states are realized by a generalization of spin network states based on
Lorentz Wilson lines projected on irreducible representations of an SO(3)
subgroup. The problem of infinite dimensionality of the unitary Lorentz
representations is absent due to this projection. Nevertheless, the projection
preserves the Lorentz covariance of the Wilson lines so that the symmetry is
not broken. Under certain conditions the states can be thought as functions on
a homogeneous space. We define the inner product as an integral over this
space. With respect to this inner product the spin networks form an orthonormal
basis in the investigated sector. We argue that it is the only relevant part of
a larger state space arising in the approach. The problem of the
noncommutativity of the Lorentz connection is solved by restriction to the
simple representations. The resulting structure shows similarities with the
spin foam approach.",0201087v1
2003-05-15,Proposal of a second generation of quantum-gravity-motivated Lorentz-symmetry tests: sensitivity to effects suppressed quadratically by the Planck scale,"Over the last few years the study of possible Planck-scale departures from
classical Lorentz symmetry has been one of the most active areas of
quantum-gravity research. We now have a satisfactory description of the fate of
Lorentz symmetry in the most popular noncommutative spacetimes and several
studies have been devoted to the fate of Lorentz symmetry in loop quantum
gravity. Remarkably there are planned experiments with enough sensitivity to
reveal these quantum-spacetime effects, if their magnitude is only linearly
suppressed by the Planck length. Unfortunately, in some quantum-gravity
scenarios even the strongest quantum-spacetime effects are suppressed by at
least two powers of the Planck length, and many authors have argued that it
would be impossible to test these quadratically-suppressed effects. I here
observe that advanced cosmic-ray observatories and neutrino observatories can
provide the first elements of an experimental programme testing the possibility
of departures from Lorentz symmetry that are quadratically Planck-length
suppressed.",0305057v2
2002-01-07,A Test of CPT and Lorentz Invariance from Muonium Spectroscopy,"Upon a suggestion of Kostelecky et al., we have performed a test of CPT and
Lorentz invariance from the microwave spectroscopy of muonium. New terms in
their standard model extension violating CPT and Lorentz symmetry would appear
as anti-correlated frequency shifts, oscillating at the earth's sidereal
frequency, in the two ground state hyperfine transitions involving muon spin
flip, $\nu_{12}$ and $\nu_{34}$, which were measured in a strong magnetic field
of 1.7 T. No such time dependence was observed in $\nu_{12}$ or $\nu_{34}$ at
the level of 20 Hz, limiting the size of some CPT and Lorentz violating
parameters with Planck scale sensitivity, and representing almost an order of
magnitude improvement over previous limits for the muon.",0201010v1
1998-09-18,Continuous space-time symmetries in a lattice field theory,"For purposes of regularization as well as numerical simulation, the
discretization of Lorentz invariant continuum field theories on a space-time
lattice is often convenient. In general, this discretization destroys the
rotational or Lorentz-frame independence of the theory, which is only recovered
in the continuum limit. The Baxter 8-vertex model may be interpreted as a
particular discretization of a self-interacting massive Dirac fermion theory in
two dimensions (the massive Thirring model). Here it is shown that, in the
8-vertex/massive Thirring model, the Lorentz frame independence of the theory
remains undisturbed on the lattice. The only effect of the discretization is to
compactify the manifold of Lorentz frames. The relationship between this
lattice Lorentz symmetry and the Yang-Baxter relations is discussed.",9809141v1
2002-04-27,The Poincare Group of Discrete Minkowskian Space-Time,"The lattice of integral points of 4-dimensional Minkowski space, together
with the inherited indefinite distance function, is considered as a model for
discrete space-time. The Lorentz and Poincare groups of this discrete
space-time are identified as subgroups of the corresponding Lie groups. The
lattice Lorentz group has irreducible projective (including linear)
representations which are restrictions of (all) finite-dimensional irreducible
projective representations of the Lorentz Lie group and hence can be used to
describe all integral and half-odd-integral helicity. The (4-torus) momentum
space has a well-defined ``light cone'' of null points and there are orbits of
the lattice Lorentz group lying entirely in the torus light cone and having the
lattice euclidean group of the plane as little group. Wigner's method for the
Poincare Lie group can then be adapted to show, in the first instance, that the
lattice Poincare group has unitary representations describing lattice free
fields of zero mass and an arbitrary Lorentz helicity, in particular chiral
fermions. There are no representations with a nonzero invariant mass.",0204027v1
1999-12-28,Lorentz- and CPT-violating extension of the standard model,"The formulation and some experimental implications of a general
Lorentz-violating extension of the standard model are reviewed. The theory
incorporates both CPT-preserving and CPT-breaking terms. It is otherwise a
conventional quantum field theory, obtained under the assumption that Lorentz
symmetry is spontaneously broken in an underlying model. The theory contains
the usual standard-model gauge structure, and it is power-counting
renormalizable. Energy and momentum are conserved. Despite the violation of
Lorentz symmetry, the theory exhibits covariance under Lorentz transformations
of the observer inertial frame. A general Lorentz-violating extension of
quantum electrodynamics can be extracted. The standard-model extension implies
potentially observable effects in a wide variety of experiments, including
among others measurements on neutral-meson oscillations, comparative studies in
Penning traps, spectroscopy of hydrogen and antihydrogen, bounds on
cosmological birefringence, measurements of muon properties, clock-comparison
tests, and observations of the baryon asymmetry.",9912528v1
2000-02-29,Constraint from Lamb Shift and Anomalous Magnetic Moment on Radiatively Induced Lorentz and CPT Violation in Quantum Electrodynamics,"We investigate the precisely measured anomalous magnetic moment and Lamb
shift as tests for the possible existence of the radiatively induced Lorentz
and CPT violation effects in quantum electrodynamics. To this end we calculate
the one-loop vacuum polarization tensor and vertex radiative correction in
dimensional reduction and on-shell renormalization scheme. We explicitly show
how the Lorentz and CPT violation sector affects the anomalous magnetic moment
and Lamb shift. Remarkably, we find infrared divergences coming from Lorentz
and CPT violating term that do not cancel in physical cross sections. This
result appears to place stringent constraints on the type of Lorentz/CPT
violating terms that can be added to the QED Lagrangian.",0002294v3
2000-06-19,Cosmic rays and TeV photons as probes of quantum properties of space-time,"It has been recently observed that small violations of Lorentz invariance, of
a type which may arise in quantum gravity, could explain both the observations
of cosmic rays above the GZK cutoff and the observations of 20-TeV gamma rays
from Markarian 501. We show here that different pictures of the short-distance
structure of space-time would lead to different manifestations of
Lorentz-invariance violation. Specifically, the deformation of Lorentz
invariance needed to resolve these observational paradoxes can only arise
within commutative short-distance pictures of space-time. In noncommutative
space-times there is no anomalous effect, at least at leading order. Also
exploiting the fact that arrival-time delays between high energy photons with
different energies would arise in both the commutative and the noncommutative
Lorentz-violation pictures, we describe an experimental programme, based on
time-of-arrival analysis of high energy photons and searches of violations of
GZK and TeV-photon limits, which could discriminate between alternative
scenarios of Lorentz-invariance breakdown and could provide and unexpected
window on the (quantum) nature of space-time at very short distances.",0006210v1
2001-06-04,Lorentz Invariance and Origin of Symmetries,"In this letter we reconsider the role of Lorentz invariance in the dynamical
generation of the observed internal symmetries. We argue that, generally,
Lorentz invariance can only be imposed in the sense that all Lorentz
non-invariant effects caused by the spontaneous breakdown of Lorentz symmetry
are physically unobservable. Remarkably, the application of this principle to
the most general relativistically invariant Lagrangian, with arbitrary
couplings for all the fields involved, leads by itself to the appearance of a
symmetry and, what is more, to the massless vector fields gauging this symmetry
in both Abelian and non-Abelian cases. In contrast, purely global symmetries
are only generated as accidental consequences of the gauge symmetry.",0106036v1
2004-04-29,Lorentz Violation in Supersymmetric Field Theories,"We construct supersymmetric Lorentz violating operators for matter and gauge
fields. We show that in the supersymmetric Standard Model the lowest possible
dimension for such operators is five, and therefore they are suppressed by at
least one power of an ultra--violet energy scale, providing a possible
explanation for the smallness of Lorentz violation and its stability against
radiative corrections. Supersymmetric Lorentz noninvariant operators do not
lead to modifications of dispersion relations at high energies thereby escaping
constraints from astrophysical searches for Lorentz violation.",0404271v4
2005-06-09,Lorentz and CPT Invariance Violation In High-Energy Neutrinos,"High-energy neutrino astronomy will be capable of observing particles at both
extremely high energies and over extremely long baselines. These features make
such experiments highly sensitive to the effects of CPT and Lorentz violation.
In this article, we review the theoretical foundation and motivation for CPT
and Lorentz violating effects, and then go on to discuss the related
phenomenology within the neutrino sector. We describe several signatures which
might be used to identify the presence of CPT or Lorentz violation in next
generation neutrino telescopes and cosmic ray experiments. In many cases,
high-energy neutrino experiments can test for CPT and Lorentz violation effects
with much greater precision than other techniques.",0506091v1
2006-08-01,CPT/Lorentz Invariance Violation and Neutrino Oscillation,"We analyze the consequences of violation of Lorentz and $CPT$ invariance in
the massless neutrino sector by deforming the canonical anti-commutation
relations for the fields. We show that, for particular choices of the
deformation, oscillation between massless neutrino species takes place when
only Lorentz invariance is violated. On the other hand, if both Lorentz and
$CPT$ invariances are violated, we show that there is no oscillation between
massless neutrino species. Comparing with the existing experimental data on
neutrino oscillations, we obtain bounds on the parameter for Lorentz invariance
violation.",0608007v4
2006-09-15,New Bounds on Isotropic Lorentz Violation,"Violations of Lorentz invariance that appear via operators of dimension four
or less are completely parameterized in the Standard Model Extension (SME). In
the pure photonic sector of the SME, there are nineteen dimensionless,
Lorentz-violating parameters. Eighteen of these have experimental upper bounds
ranging between 10^{-11} and 10^{-32}; the remaining parameter, k_tr, is
isotropic and has a much weaker bound of order 10^{-4}. In this Brief Report,
we point out that k_tr gives a significant contribution to the anomalous
magnetic moment of the electron and find a new upper bound of order 10^{-8}.
With reasonable assumptions, we further show that this bound may be improved to
10^{-14} by considering the renormalization of other Lorentz-violating
parameters that are more tightly constrained. Using similar renormalization
arguments, we also estimate bounds on Lorentz violating parameters in the pure
gluonic sector of QCD.",0609150v2
2006-10-16,Implications of SU(2)_L x U(1) Symmetry for SIM(2) Invariant Neutrino Masses,"We consider SU(2)_L x U(1) gauge invariant generalizations of a nonlocal,
Lorentz violating mass term for neutrinos that preserves a SIM(2) subgroup.
This induces Lorentz violating effects in QED as well as tree-level lepton
family number violating interactions. Measurements of g_e - 2 with trapped
electrons severely constrain possible SIM(2) mass terms for electrons which
violate C invariance. We study Lorentz violating effects in a C invariant and
SIM(2) invariant extension of QED. We examine the Lorentz violating
interactions of nonrelativistic electrons with electromagnetic fields to
determine their impact on the spectroscopy of hydrogen-like atoms and g_e - 2
measurements with trapped electrons. Generically, Lorentz violating corrections
are suppressed by m_\nu^2/m_e^2 and are within experimental limits. We study
one-loop corrections to electron and photon self-energies and point out the
need for a prescription to handle IR divergences induced by the nonlocality of
the theory. We also calculate the tree level contribution to \mu to e + \gamma
from SIM(2) invariant mass terms.",0610202v1
1998-04-07,Lorentz covariant spin two superspaces,"Superalgebras including generators having spins up to two and realisable as
tangent vector fields on Lorentz covariant generalised superspaces are
considered. The latter have a representation content reminiscent of
configuration spaces of (super)gravity theories. The most general canonical
supercommutation relations for the corresponding phase space coordinates
allowed by Lorentz covariance are discussed. By including generators
transforming according to every Lorentz representation having spin up to two,
we obtain, from the super Jacobi identities, the complete set of quadratic
equations for the Lorentz covariant structure constants. These defining
equations for spin two Heisenberg superalgebras are highly overdetermined.
Nevertheless, non-trivial solutions can indeed be found. By making some
simplifying assumptions, we explicitly construct several classes of these
superalgebras.",9804052v2
2003-07-16,Gravity from Spinors,"We investigate a possible unified theory of all interactions which is based
only on fundamental spinor fields. The vielbein and metric arise as composite
objects. The effective quantum gravitational theory can lead to a modification
of Einstein's equations due to the lack of local Lorentz-symmetry. We explore
the generalized gravity with global instead of local Lorentz symmetry in first
order of a systematic derivative expansion. At this level diffeomorphisms and
global Lorentz symmetry allow for two new invariants in the gravitational
effective action. The one which arises in the one loop approximation to spinor
gravity is consistent with all present tests of general relativity and
cosmology. This shows that local Lorentz symmetry is tested only very partially
by present observations. In contrast, the second possible new coupling is
severely restricted by present solar system observations.",0307145v3
2003-10-16,Space-Time Symmetries in Noncommutative Gauge Theory: A Hamiltonian Analysis,"We study space-time symmetries in Non-Commutative (NC) gauge theory in the
(constrained) Hamiltonian framework. The specific example of NC CP(1) model,
posited in \cite{sg}, has been considered. Subtle features of Lorentz
invariance violation in NC field theory were pointed out in \cite{har}. Out of
the two - Observer and Particle - distinct types of Lorentz transformations,
symmetry under the former, (due to the translation invariance), is reflected in
the conservation of energy and momentum in NC theory. The constant tensor
$\theta_{\mu\nu}$ (the noncommutativity parameter) destroys invariance under
the latter.
  In this paper we have constructed the Hamiltonian and momentum operators
which are the generators of time and space translations respectively. This is
related to the Observer Lorentz invariance. We have also shown that the
Schwinger condition and subsequently the Poincare algebra is not obeyed and
that one can not derive a Lorentz covariant dynamical field equation. These
features signal a loss of the Particle Lorentz symmetry. The basic observations
in the present work will be relevant in the Hamiltonian study of a generic
noncommutative field theory.",0310155v3
2004-02-20,Searching for Lorentz Violation,"Astrophysical, terrestrial, and space-based searches for Lorentz violation
are very briefly reviewed. Such searches are motivated by the fact that all
superunified theories (and other theories that attempt to include quantum
gravity) have some potential for observable violations of Lorentz invariance.
Another motivation is the exquisite sensitivity of certain well-designed
experiments and observations to particular forms of Lorentz violation. We also
review some new predictions of a specific Lorentz-violating theory: If a
fundamental energy \bar{m} in this theory lies below the usual GZK cutoff
E_{GZK}, the cutoff is shifted to infinite energy; i.e., it no longer exists.
On the other hand, if \bar{m} lies above E_{GZK}, there is a high-energy branch
of the fermion dispersion relation which provides an alternative mechanism for
super-GZK cosmic-ray protons.",0402154v1
2004-04-19,Relativistic Spinor Dynamics Inducing the Extended Lorentz-Force-Like Equation,"The special relativistic dynamical equation of the Lorentz force type can be
regarded as a consequence of a succession of space-time dependent infinitesimal
Lorentz transformations as shown by one of us \cite{buitrago} and discussed in
the introduction below. Such an insight indicates that the Lorentz-force-like
equation has an extremely fundamental meaning in physics. In this paper we
therefore present a set of dynamical Weyl spinor equations {\em inducing} the
extended Lorentz-force-like equation in the Minowski space-time. The term
extended refers to the dynamics of some additional degrees of freedom that may
be associated with the classical spin namely with the dynamics of three
space-like mutually orthogonal four-vectors, all of them orthogonal to the
linear four-momentum of the object under consideration.",0404129v1
2004-10-10,Non-Minimal Coupling to a Lorentz-Violating Background and Topological Implications,"The non-minimal coupling of fermions to a background responsible for the
breaking of Lorentz symmetry is introduced in Dirac's equation; the
non-relativistic regime is contemplated, and the Pauli's equation is used to
show how an Aharonov-Casher phase may appear as a natural consequence of the
Lorentz violation, once the particle is placed in a region where there is an
electric field. Different ways of implementing the Lorentz breaking are
presented and, in each case, we show how to relate the Aharonov-Casher phase to
the particular components of the background vector or tensor that realises the
violation of Lorentz symmetry.",0410104v2
2005-06-30,Defect Structures in Lorentz and CPT Violating Scenarios,"We investigate models described by real scalar fields, searching for defect
structures in the presence of interactions which explicitly violate Lorentz and
CPT symmetries. We first deal with a single field, and we investigate a class
of models which supports traveling waves that violate Lorentz invariance. This
scenario is then generalized to the case of two (or more) real scalar fields.
In the case of two fields, in particular, we introduce another class of models,
which supports topological structures that attain a Bogomol'nyi bound, although
violating both Lorentz and CPT symmetries. An example is considered, for which
we construct the Bogomol'nyi bound and find some explicit solutions. We show
that violation of both Lorentz and CPT symmetries induces the appearance of an
asymmetry between defects and anti-defects, including the presence of linearly
stable solutions with negative energy density in their outer side.",0506262v3
2005-11-15,Lorentz symmetry violation without violation of relativistic symmetry,"Within the framework of the Finslerian approach to the problem of violation
of Lorentz symmetry, consideration is given to a flat axially symmetric
Finslerian space of events, which is the generalization of Minkowski space.
Such an event space arises from the spontaneous breaking of initial gauge
symmetry and from the formation of anisotropic fermion-antifermion condensate.
It is shown that the appearance of an anisotropic condensate breaks Lorentz
symmetry; relativistic symmetry, realized by means of the 3-parameter group of
generalized Lorentz boosts, remains valid here nevertheless. We have obtained
the bispinor representation of the group of generalized Lorentz boosts, which
makes it possible to construct the Lagrangian for an interaction of fundamental
fields with anisotropic condensate.",0511151v1
2006-03-01,Lorentz Invariance Violation and its Role in Quantum Gravity Phenomenology,"The notion that gravitation might lead to a breakdown of standard space-time
structure at small distances, and that this might affect the propagation of
ordinary particles has led to a program to search for violations of Lorentz
invariance as a probe of quantum gravity. Initially it was expected that
observable macroscopic effects caused by microscopic violations of Lorentz
invariance would necessarily be suppressed by at least one power of the small
ratio between the Planck length and macroscopic lengths. Here we discuss the
implications of the fact that this expectation is in contradiction with
standard properties of radiative corrections in quantum field theories. In
normal field theories, radiative corrections in the presence of microscopic
Lorentz violation give macroscopic Lorentz violation that is suppressed only by
the size of Standard Model couplings, in clear conflict with observation. In
general, this conclusion can only be avoided by extreme fine tuning of the
parameters of the theory.",0603002v1
2007-01-10,Lorentz-violating dilatations in the momentum space and some extensions on non-linear actions of Lorentz algebra-preserving systems,"We work on some general extensions of the formalism for theories which
preserve the relativity of inertial frames with a nonlinear action of the
Lorentz transformations on momentum space. Relativistic particle models
invariant under the corresponding deformed symmetries are presented with
particular emphasis on deformed dilatation transformations. The algebraic
transformations relating the deformed symmetries with the usual (undeformed)
ones are provided in order to preserve the Lorentz algebra. Two distinct cases
are considered: a deformed dilatation transformation with a spacelike preferred
direction and a very special relativity embedding with a lightlike preferred
direction. In both analysis we consider the possibility of introducing quantum
deformations of the corresponding symmetries such that the spacetime
coordinates can be reconstructed and the particular form of the real
space-momentum commutator remains covariant. Eventually feasible experiments,
for which Lorentz violating effects here pointed out may be detectable, are
suggested.",0701094v2
2007-02-15,Consistent Lorentz Violation in Flat and Curved Space,"Motivated by the severity of the bounds on Lorentz violation in the presence
of ordinary gravity, we study frameworks in which Lorentz violation does not
affect the spacetime geometry. We show that there are at least two inequivalent
classes of spontaneous Lorentz breaking that even in the presence of gravity
result in Minkowski space. The first one generically corresponds to the
condensation of tensor fields with tachyonic mass which in turn is related to
ghost-condensation. In the second class, realized by the DGP model or theories
of massive gravitons, spontaneous Lorentz breaking is induced by the
expectation value of sources. The generalization to de-Sitter space is also
discussed.",0702117v2
2007-03-28,Géométries Lorentziennes de dimension 3 : classification et complétude,"We study 3-dimensional non-Riemannian Lorentz geometries, i.e. compact
locally homogeneous Lorentz 3-manifolds with non-compact (local) isotropy
group. One result is that, up to a finite cover, all such manifolds admit
Lorentz metrics of (non-positive) constant sectionnal curvature. If the
geometry is maximal, then the metric has constant sectionnal curvature, or is a
left invariant metric on the Heisenberg group or the Sol group. These
geometries, on each of the latter two groups are characterized by having a
non-compact isotropy without being flat.
  Recall, for the need of his formulation of the geometrization conjecture, W.
Thurston counted the 8 maximal Riemannian geometries in dimension 3. Here, we
count only 4 maximal Lorentz geometries, but ignoring those which are at the
same time Riemannian.
  Also, all such manifolds are geodesically complete, except the previous non
flat left invariant Lorentz metric on the SOL group.",0703846v2
1997-03-28,Jones-matrix Formalism as a Representation of the Lorentz Group,"It is shown that the two-by-two Jones-matrix formalism for polarization
optics is a six-parameter two-by-two representation of the Lorentz group. The
attenuation and phase-shift filters are represented respectively by the
three-parameter rotation subgroup and the three-parameter Lorentz group for two
spatial and one time dimensions. It is noted that the Lorentz group has another
three-parameter subgroup which is like the two-dimensional Euclidean group.
Possible optical filters having this Euclidean symmetry are discussed in
detail. It is shown also that the Jones-matrix formalism can be extended to
some of the non-orthogonal polarization coordinate systems within the framework
of the Lorentz-group representation.",9703032v1
1997-04-14,"Vacuum Structure, Lorentz Symmetry and Superluminal Particles","If textbook Lorentz invariance is actually a property of the equations
describing a sector of the excitations of vacuum above some critical distance
scale, several sectors of matter with different critical speeds in vacuum can
coexist and an absolute rest frame (the vacuum rest frame) may exist without
contradicting the apparent Lorentz invariance felt by ""ordinary"" particles
(particles with critical speed in vacuum equal to $c$ , the speed of light).
The sectorial Lorentz symmetry may be only a low-energy limit, in the same way
as the relation $\omega $ (frequency) = $c_s$ (speed of sound) $k$ (wave
vector) holds for low-energy phonons in a crystal. We study the consequences of
such a scenario, using an ansatz inspired by the Bravais lattice as a model for
some vacuum properties. It then turns out that: a) the Greisen-Zatsepin-Kuzmin
cutoff on high-energy cosmic protons and nuclei does no longer apply; b)
high-momentum unstable particles have longer lifetimes than expected with exact
Lorentz invariance, and may even become stable at the highest observed cosmic
ray energies or slightly above. Some cosmological implications of superluminal
particles are also discussed.",9704017v1
1998-10-29,From the Field Electron Model to the Unified Field Theory,"The unified field is a Maxwell-Lorentz field. Maxwell-Lorentz equations for
potentials in standard four-dimensional form are satisfied exactly. This is
achieved by involving new fundamental field sources, strict definition of which
requires higher dimensionality. Source currents do not ""see"" each other enough
that, in each point of the space in any direction, there is a couple of
currents with different charge signs. Each such charged source moves in the
Maxwell-Lorentz field in accordance with the law of motion, and each of them,
independently of the others, generates field in accordance with Maxwell-Lorentz
equations. The law of motion may be found from the condition of existence of a
solution in the form of stabile and identical electrons with ""necessary""
properties. The law of motion to be found is defined strictly enough by the
condition of electron generation! If an electron exists that means that
protons, atoms and the Universe exist too! All particles and fields - they are
just visible exhibitions of interaction between the Maxwell-Lorentz field and
its sources!",9810059v1
2000-07-18,New Clock Comparison Searches for Lorentz and CPT Violation,"We present two new measurements constraining Lorentz and CPT violation using
the Xe-129 / He-3 Zeeman maser and atomic hydrogen masers. Experimental
investigations of Lorentz and CPT symmetry provide important tests of the
framework of the standard model of particle physics and theories of gravity.
The two-species Xe-129 / He-3 Zeeman maser bounds violations of CPT and Lorentz
symmetry of the neutron at the 10^-31 GeV level. Measurements with atomic
hydrogen masers provide a clean limit of CPT and Lorentz symmetry violation of
the proton at the 10^-27 GeV level.",0007063v1
2004-09-20,"Derivation of the Lorentz Force Law, the Magnetic Field Concept and the Faraday-Lenz Law using an Invariant Formulation of the Lorentz Transformation","It is demonstrated how the right hand sides of the Lorentz Transformation
equations may be written, in a Lorentz invariant manner, as 4--vector scalar
products. This implies the existence of invariant length intervals analogous to
invariant proper time intervals. This formalism, making essential use of the
4-vector electromagnetic potential concept, provides a short derivation of the
Lorentz force law of classical electrodynamics, the conventional definition of
the magnetic field, in terms of spatial derivatives of the 4--vector potential
and the Faraday-Lenz Law. An important distinction between the physical
meanings of the space-time and energy-momentum 4--vectors is pointed out.",0409103v2
2004-10-27,A New Kinematical Derivation of the Lorentz Transformation and the Particle Description of Light,"The Lorentz Transformation is derived from only three simple postulates:
  (i) a weak kinematical form of the Special Relativity Principle that requires
the equivalence of reciprocal space-time measurements by two different inertial
observers;
  (ii) Uniqueness, that is the condition that the Lorentz Transformation should
be a single valued function of its arguments;
  (iii) Spatial Isotropy.
  It is also shown that to derive the Lorentz Transformation for space-time
points lying along a common axis, parallel to the relative velocity direction,
of two inertial frames, postulates (i) and (ii) are sufficient. The kinematics
of the Lorentz Transformation is then developed to demonstrate that, for
consistency with Classical Electrodynamics, light must consist of massless (or
almost massless) particles: photons.",0410262v1
2006-12-05,The physics of space and time I: The description of rulers and clocks in uniform translational motion by Galilean or Lorentz transformations,"A calculus based on pointer-mark coincidences is proposed to define, in a
mathematically rigorous way, measurements of space and time intervals. The
connection between such measurements in different inertial frames according to
the Galilean or Lorentz transformations is then studied using new, simple, and
practical clock synchronisation procedures. It is found that measured length
intervals are Lorentz invariant, whereas moving clocks show a universal time
dilatation effect. The `relativistic length contraction' and `relativity of
simultaneity' effects of conventional special relativity theory are shown to be
the consequence of calculational error. Two derivations of the Lorentz
transformation from simple postulates, without reference to electrodynamics or
any other dynamical theory, are reviewed in an appendix.",0612039v4
2007-03-12,Incompatibility between the principle of the constancy of the speed of light and the Lorentz contraction in the GPS Experiment,"Incompatibility between the principle of the constancy of the speed of light
and the Lorentz contraction in the global positioning system (GPS) is
discussed. The GPS works precisely in the earth-centered locally inertial (ECI)
coordinate system on the condition that the speed of light c is assumed to be
constant regardless of the inertial motion of the GPS satellites and the earth.
The inertial system of the earth travels not only in the solar system at the
velocity 30 km/s but also in the cosmic microwave background (CMB) at the
velocity 700 km/s. The deviation on the car navigation system by the Lorentz
contraction of 700 km/s is maximally estimated as 54 m. However, such a large
deviation is not observed: that is, the Lorentz contraction is not observed in
the gravitational field of the earth. If there is a Lorentz contraction, the
GPS cannot work so precisely. The GPS satellites are in the gravitational field
of the earth, therefore the system should be interpreted by the theory of
general relativity as well as special relativity.",0703123v1
2003-07-16,"Wigner rotations, Bell states, and Lorentz invariance of entanglement and von Neumann entropy","We compute, for massive particles, the explicit Wigner rotations of
one-particle states for arbitrary Lorentz transformations; and the explicit
Hermitian generators of the infinite-dimensional unitary representation. For a
pair of spin 1/2 particles, Einstein-Podolsky-Rosen-Bell entangled states and
their behaviour under the Lorentz group are analysed in the context of quantum
field theory. Group theoretical considerations suggest a convenient definition
of the Bell states which is slightly different from the conventional
assignment. The behaviour of Bell states under arbitrary Lorentz
transformations can then be described succinctly. Reduced density matrices
applicable to identical particles are defined through Yang's prescription. The
von Neumann entropy of each of the reduced density matrix is Lorentz invariant;
and its relevance as a measure of entanglement is discussed, and illustrated
with an explicit example. A regularization of the entropy in terms of
generalized zeta functions is also suggested.",0307107v4
2004-01-18,Lorentz Group in Ray Optics,"It has been almost one hundred years since Einstein formulated his special
theory of relativity in 1905. He showed that the basic space-time symmetry is
dictated by the Lorentz group. It is shown that this group of Lorentz
transformations is not only applicable to special relativity, but also
constitutes the scientific language for optical sciences. It is noted that
coherent and squeezed states of light are representations of the Lorentz group.
The Lorentz group is also the basic underlying language for classical ray
optics, including polarization optics, interferometers, the Poincare\'e sphere,
one-lens optics, multi-lens optics, laser cavities, as well multilayer optics.",0401098v1
2007-12-10,Astrophysical Limits on Lorentz Violation for Pions,"Pions, like nucleons, are composed primarily of up and down quarks and
gluons. Constraints on spin-independent Lorentz violation in the proton,
neutron, and pion sectors translate into bounds on Lorentz violation for the
fundamental fields. The best bounds on pion Lorentz violation come from
astrophysical measurements. The absence of the absorption process gamma -->
pi^(+) + pi^(-) for up to 50 TeV photons constrains the possibility that pions'
maximum achievable velocities are less than 1 at the 1.5 x 10^(-11) level. The
fact that pions with energies up to 30 TeV are observed to decay into photons
rather than hadrons bounds the possibility of a maximum velocity greater than 1
at the $2 x 10^(-9) level. This provides the first two-sided bounds on Lorentz
violation for pions.",0712.1579v1
2007-12-27,The Lorentz Extension as Consequence of the Family Symmetry,"In this paper we postulate an algebraic model to explain how the symmetry of
three lepton species plays its role in the Lorentz extension. Inspired by the
two-to-one mapping between the group SL (2, C) and the Lorentz group, we design
a mapping between SL (3, C) group, which displays the family symmetry, and a
generalized Lorentz group. Following the conventional method, we apply the
mapping results to Dirac equation to discuss its transformation invariance, and
it turns out that only when the vertex matrix is extended to the combination
can the Dirac-equation-form be reserved. At the same time we find that the
Lorentz group has to be extended with an additional generator . The generalized
vertex matrix is helpful in understanding the axial-like form of weak
interaction and the neutrino oscillations.",0712.4188v2
2008-03-17,Crossing of the Phantom Divided Barrier with Lorentz Invariance Violating Fields,"We study possible crossing of the phantom divided barrier in a Lorentz
invariance violating dark energy model. Lorentz invariance violation which is
achieved by introducing a vector field in the action, incorporates directly in
the dynamics of the scalar field and equation of state. This interesting
feature allows us to study phantom divided barrier crossing in the context of
Lorentz invariance violation. We show that for suitable choice of parameter
space, equation of state can cross phantom divided barrier just by one scalar
field and Lorentz violating vector field controls this crossing.",0803.2398v2
2008-04-21,Once again about quantum deformations of D=4 Lorentz algebra: twistings of q-deformation,"This paper together with the previous one (arXiv:hep-th/0604146) presents the
detailed description of all quantum deformations of D=4 Lorentz algebra as Hopf
algebra in terms of complex and real generators. We describe here in detail two
quantum deformations of the D=4 Lorentz algebra o(3,1) obtained by twisting of
the standard q-deformation U_{q}(o(3,1)). For the first twisted q-deformation
an Abelian twist depending on Cartan generators of o(3,1) is used. The second
example of twisting provides a quantum deformation of Cremmer-Gervais type for
the Lorentz algebra. For completeness we describe also twisting of the Lorentz
algebra by standard Jordanian twist. By twist quantization techniques we obtain
for these deformations new explicit formulae for the deformed coproducts and
antipodes of the o(3,1)-generators.",0804.3305v1
2008-05-08,GLAST and Lorentz violation,"We study possible Lorentz violations by means of gamma-ray bursts (GRB) with
special focus on the Large Array Telescope (LAT) of GLAST. We simulate bursts
with gtobssim and introduce a Lorentz violating term in the arrival times of
the photons. We further perturb these arrival times and energies with a
Gaussian distribution corresponding to the time resp. energy resolution of
GLAST. We then vary the photon flux in gtobssim in order to derive a relation
between the photon number and the standard deviation of the Lorentz violating
term. We conclude with the fact that our maximum likelihood method as first
developed in [1] is able to make a statement whether Nature breaks the Lorentz
symmetry if the number of bursts with known redshifts is of the order of 100.",0805.1219v2
2008-05-14,Lorentz violation dispersion relation and its application,"We derive a modified dispersion relation (MDR) in the Lorentz violation
extension of quantum electrodynamics (QED) sector in the standard model
extension (SME) framework. Based on the extended Dirac equation and
corresponding MDR, we observe the resemblance of the Lorentz violation coupling
with spin-gravity coupling. We also develop a neutrino oscillation mechanism
induced by the presence of nondiagonal terms of Lorentz violation couplings in
2-flavor space in a 2-spinor formalism by explicitly assuming neutrinos to be
Marjorana fermions. We also obtain a much stringent bound ($\backsim10^{-25}$)
on one of the Lorentz violation parameters by applying MDR to the ultrahigh
energy cosmic ray (UHECR) problem.",0805.2012v4
2008-05-15,Special Relativity and possible Lorentz violations consistently coexist in Aristotle space-time,"Some studies interpret quantum measurement as being explicitly non local.
Others assume the preferred frame hypothesis. Unfortunately, these two classes
of studies conflict with Minkowski space-time geometry. On the contrary, in
Aristotle space-time, Lorentz invariance, interpreted as a physical property
applying to all phenomena actually satisfying this symmetry (as opposed to a
geometrical constraint applying to an assumed pre-existing Minkowski
space-time) consistently coexists with possible Lorentz violations. Moreover,
as will be pointed out, the geometrical framework provided by Aristotle
space-time is in fact necessary to derive the Lorentz transformations from
physical hypotheses.",0805.2417v1
2008-06-07,Magnetic Moment Generation from non-minimal couplings in a scenario with Lorentz-Symmetry Violation,"This paper deals with situations that illustrate how the violation of Lorentz
symmetry in the gauge sector may contribute to magnetic moment generation of
massive neutral particles with spin-1/2 and spin-1. The procedure we adopt here
is based on Relativistic Quantum Mechanics. We work out the non-relativistic
regime that follows from the wave equation corresponding to a certain particle
coupled to an external electromagnetic field and a background that accounts for
the Lorentz symmetry violation, and we read thereby the magnetic dipole moment
operator for the particle under consideration.We keep track of the parameters
that govern the non-minimal electromagnetic coupling and the breaking of
Lorentz symmetry in the expressions we get for the magnetic moments in the
different cases we contemplate. Our claim is that the tiny magnetic dipole
moment of truly elementary neutral particles might signal Lorentz symmetry
violation.",0806.1253v2
2008-08-01,Nonstandard Lorentz-Einstein transformations,"The standard Lorentz transformations establish a relationship between the
space-time coordinates of the same event when detected from two inertial
reference frames I and I' in the standard arrangement. This event is
characterized by the space-time coordinates E(x,tE) and E'(x',t'E), tE and t'E
representing the readings of the standard synchronized clocks C(x) and C'(x')
located in the two frames where the event takes place. We obtain the
nonstandard Lorentz transformations establishing a ""physically"" correct
relationship between the readings of the standard synchronized clocks and the
readings of other clocks (ta,t'a) of the same inertial reference frames. This
relationship of the type tE=f(x,ta), expresses the standard Lorentz
transformations as a function of ta and t'a respectively. We present several
cases of nonstandard Lorentz transformation (the case of radar detection, the
case when one reference frame is filled with an ideal transparent dielectric
and the case of relativity of the apparent, actual and synchronized positions
of the same moving particle).",0808.0098v1
2008-12-08,CMB anisotropy induced by tachyonic perturbations of dark energy,"We study effects of possible tachyonic perturbations of dark energy on the
CMB temperature anisotropy. Motivated by some models of phantom energy, we
consider both Lorentz-invariant and Lorentz-violating dispersion relations for
tachyonic perturbations. We show that in the Lorentz-violating case, the shape
of the CMB anisotropy spectrum generated by the tachyonic perturbations is very
different from that due to adiabatic scalar perturbations and, if sizeable, it
would be straightforwardly distinguished from the latter. The tachyonic
contribution improves slightly the agreement between the theory and data;
however, this improvement is not statistically significant, so our analysis
results in limits on the time scale of the tachyonic instability. In the
Lorentz-invariant case, tachyonic contribution is a rapidly decaying function
of the multipole number $l$, so that the entire observed dipole can be
generated without conflicting the data at higher multipoles. On the
conservative side, our comparison with the data places limit on the absolute
value of the (imaginary) tachyon mass in the Lorentz-invariant case.",0812.1459v2
2009-01-14,Spinor extended Lorentz-force like equations as consequence of a spinorial structure of space-time,"As previously shown, the special relativistic dynamical equation of the
Lorentz force type can be regarded as a consequence of a succession of
space-time dependent infinitesimal Lorentz boosts and rotations. This insight
indicate that the Lorentz-Force-like equation has a fundamental meaning in
physics. We show how this result may be spinorially obtained starting out out
from the application of an infinitesimal element of SL(2,C) to the individual
spinors, which are regarded here as being more fundamental objects than
four-vectors. In this way we get a set of new dynamical spinor equations
inducing the extended Lorentz-Force-like equation in the Minkowski space-time
and geometrically obtain the spinor form of the electromagnetic field tensor.
The term extended refers to the dynamics of some additional degrees of freedom
that may be associated with the intrinsic spin, namely, with the dynamics of
three spacelike mutually orthogonal four-vectors, all of them orthogonal to the
linear four-momentum of the object under consideration that finally, in the
particle's proper frame. are identified with the generators of SU(2).",0901.1979v1
2009-03-12,Vector models of gravitational Lorentz symmetry breaking,"Spontaneous Lorentz symmetry breaking can occur when the dynamics of a tensor
field cause it to take on a non-zero expectation value in vacuo, thereby
providing one or more ""preferred directions"" in spacetime. Couplings between
such fields and spacetime curvature will then affect the dynamics of the
metric, leading to interesting gravitational effects. Bailey & Kostelecky
developed a post-Newtonian formalism that, under certain conditions concerning
the field's couplings and stress-energy, allows for the analysis of
gravitational effects in the presence of Lorentz symmetry breaking. We perform
a systematic survey of vector models of spontaneous Lorentz symmetry breaking.
We find that a two-parameter class of vector models, those with kinetic terms
we call ""pseudo-Maxwell,"" can be successfully analyzed under the
Bailey-Kostelecky formalism, and that one of these two ""dimensions"" in
parameter space has not yet been explored as a possible mechanism of
spontaneous Lorentz symmetry breaking.",0903.2279v2
2009-04-12,Standard Model Without Elementary Scalars And High Energy Lorentz Violation,"If Lorentz symmetry is violated at high energies, interactions that are
usually non-renormalizable can become renormalizable by weighted power
counting. Recently, a CPT invariant, Lorentz violating extension of the
Standard Model containing two scalar-two fermion interactions (which can
explain neutrino masses) and four fermion interactions (which can explain
proton decay) was proposed. In this paper we consider a variant of this model,
obtained suppressing the elementary scalar fields, and argue that it can
reproduce the known low energy physics. In the Nambu--Jona-Lasinio spirit, we
show, using a large N_c expansion, that a dynamical symmetry breaking takes
place. The effective potential has a Lorentz invariant minimum and the Lorentz
violation does not reverberate down to low energies. The mechanism generates
fermion masses, gauge-boson masses and scalar bound states, to be identified
with composite Higgs bosons. Our approach is not plagued by the ambiguities of
approaches based on non-renormalizable vertices. The low-energy effective
action is uniquely determined and predicts relations among parameters of the
Standard Model.",0904.1849v1
2009-05-12,Atom interferometry tests of local Lorentz invariance in gravity and electrodynamics,"We present atom-interferometer tests of the local Lorentz invariance of
post-Newtonian gravity. An experiment probing for anomalous vertical gravity on
Earth, which has already been performed by us, uses the highest-resolution
atomic gravimeter so far. The influence of Lorentz violation in electrodynamics
is also taken into account, resulting in combined bounds on Lorentz violation
in gravity and electrodynamics. Expressed within the standard model extension
or Nordtvedt's anisotropic universe model, we limit twelve linear combinations
of seven coefficients for Lorentz violation at the part per billion level, from
which we derive limits on six coefficients (and seven when taking into account
additional data from lunar laser ranging). We also discuss the use of
horizontal interferometers, including atom-chip or guided-atom devices, which
potentially allow the use of longer coherence times in order to achieve higher
sensitivity.",0905.1929v2
2009-06-03,Lorentz Violation: Motivation and new constraints,"We review the main theoretical motivations and observational constraints on
Planck scale suppressed violations of Lorentz invariance. After introducing the
problems related to the phenomenological study of quantum gravitational
effects, we discuss the main theoretical frameworks within which possible
departures from Lorentz invariance can be described. In particular, we focus on
the framework of Effective Field Theory, describing several possible ways of
including Lorentz violation therein and discussing their theoretical viability.
We review the main low energy effects that are expected in this framework. We
discuss the current observational constraints on such a framework, focusing on
those achievable through high-energy astrophysics observations. In this context
we present a summary of the most recent and strongest constraints on QED with
Lorentz violating non-renormalizable operators. Finally, we discuss the present
status of the field and its future perspectives.",0906.0681v4
2009-07-10,QCD's Partner needed for Mass Spectra and Parton Structure Functions,"As in the case of the hydrogen atom, bound-state wave functions are needed to
generate hadronic spectra. For this purpose, in 1971, Feynman and his students
wrote down a Lorentz-invariant harmonic oscillator equation. This differential
equation has one set of solutions satisfying the Lorentz-covariant boundary
condition. This covariant set generates Lorentz-invariant mass spectra with
their degeneracies. Furthermore, the Lorentz-covariant wave functions allow us
to calculate the valence parton distribution by Lorentz-boosting the
quark-model wave function from the hadronic rest frame. However, this boosted
wave function does not give an accurate parton distribution. The wave function
needs QCD corrections to make a contact with the real world. Likewise QCD needs
the wave function as a starting point for calculating the parton structure
function.",0907.1854v1
2009-10-22,"Neutrino Oscillations, Lorentz/CPT Violation, and Dark Energy","If dark energy (DE) couples to neutrinos, then there may be apparent
violations of Lorentz/CPT invariance in neutrino oscillations. The DE-induced
Lorentz/CPT violation takes a specific form that introduces neutrino
oscillations that are energy independent, differ for particles and
antiparticles, and can lead to novel effects for neutrinos propagating through
matter. We show that ultra-high-energy neutrinos may provide one avenue to seek
this type of Lorentz/CPT violation in \nu_\mu-\nu_\tau oscillations, improving
the current sensitivity to such effects by seven orders of magnitude.
Lorentz/CPT violation in electron-neutrino oscillations may be probed with the
zenith-angle dependence for high-energy atmospheric neutrinos. The ``smoking
gun,'' for DE-neutrino coupling would, however, be a dependence of neutrino
oscillations on the direction of the neutrino momentum relative to our peculiar
velocity with respect to the CMB rest frame. While the amplitude of this
directional dependence is expected to be small, it may nevertheless be worth
seeking in current data and may be a target for future neutrino experiments.",0910.4391v1
2009-11-10,Lorentz Violation and Gravity,"In the last decade, a variety of high-precision experiments have searched for
miniscule violations of Lorentz symmetry. These searches are largely motivated
by the possibility of uncovering experimental signatures from a fundamental
unified theory. Experimental results are reported in the framework called the
Standard-Model Extension (SME), which describes general Lorentz violation for
each particle species in terms of its coefficients for Lorentz violation.
Recently, the role of gravitational experiments in probing the SME has been
explored in the literature. In this talk, I will summarize theoretical and
experimental aspects of these works. I will also discuss recent lunar laser
ranging and atom interferometer experiments, which place stringent constraints
on gravity coefficients for Lorentz violation.",0911.1816v1
2010-03-25,Polymer rheology simulations at the meso- and macroscopic scale,"We show that simulations of polymer rheology at a fluctuating mesoscopic
scale and at the macroscopic scale where flow instabilities occur can be
achieved at the same time with dissipative particle dynamics (DPD) technique.}
We model the visco-elasticity of polymer liquids by introducing a finite
fraction of dumbbells in the standard DPD fluid. The stretching and tumbling
statistics of these dumbbells is in agreement with what is known for isolated
polymers in shear flows. At the same time, the model exhibits behaviour
reminiscent of drag reduction in the turbulent state: as the polymer fraction
increases, the onset of turbulence in plane Couette flow is pushed to higher
Reynolds numbers. The method opens up the possibility to model nontrivial
rheological conditions with ensuing coarse grained polymer statistics.",1003.4895v2
2010-06-23,How to explain the Michelson-Morley experiment in ordinary 3-dimensional space,"The Michelson-Morley experiment led Einstein to introduce the concept of
spacetime and to propose that all of the laws of physics are Lorentz invariant.
However, so far only the Lorentz invariance of electromagnetism has been
convincingly confirmed. I would like to propose a new way to explain the
Michelson-Morley experiment that retains the Lorentz invariance of Maxwell's
equations without requiring the other laws of physics to be Lorentz invariant.
In this new theory Lorentz invariance is not fundamental, but instead is simply
a consequence of the fact that Maxwell's equations are incomplete because they
lack a way to define local inertial reference frames. This new theory
explicitly defines 3-dimensional local inertial reference frames in terms of
the gravitational potential $\VG{}$ along with a momentum potential $\VP{}$ and
a force potential $\VF{}$. This new theory decouples space and time, and
explains the Michelson-Morley experiment in ordinary 3-dimensional space.",1006.4596v5
2010-09-21,The bulk Lorentz factor of outflow powering X-ray flare in GRB afterglow,"We develop two methods to estimate the bulk Lorentz factor of X-ray flare
outflow. In the first method the outflow is assumed to be baryonic and is
accelerated by the thermal pressure, for which the final bulk Lorentz factor is
limited by the outflow luminosity as well as the initial radius of the outflow
getting accelerated. Such a method may be applied to a considerable fraction of
flares. The second method, based on the curvature effect interpretation of the
quick decline of the flare, can give a tightly constrained estimate of the bulk
Lorentz factor but can only be applied to a few giant flares. The results
obtained in these two different ways are consistent with each other. The
obtained bulk Lorentz factor (or just upper limit) of the X-ray flare outflows,
ranging from ten to a few hundred, is generally smaller than that of the
Gamma-ray Burst (GRB) outflows.",1009.3989v1
2011-02-15,"Comment on ""Noncommutative gauge theories and Lorentz symmetry, Phys. Rev. D {\bf 70}, 125004 (2004) by R.Banerjee, B.Chakraborty and K.Kumar""","We show that Lorentz symmetry is generally absent for noncommutative
(abelian) gauge theories and obtain a compact formula for the divergence of the
Noether currents that allows a throughout study of this instance of symmetry
violation. We use that formula to explain why the results of ""Noncommutative
gauge theories and Lorentz symmetry"", Phys. Rev. D {\bf 70}, 125004 (2004) by
R.Banerjee, B.Chakraborty and K.Kumar, interpreted there as new criteria for
Lorentz {\it invariance}, are in fact just a particular case of the general
expression for Lorentz {\it violation} obtained here. Finally, it is suggested
that the divergence-formula should hold in a vast class of cases, such as, for
instance, the Standard Model Extension.",1102.3027v1
2011-03-08,Future limits on isotropic Lorentz violation in the photon sector from UHECRs and TeV gamma rays,"Present and future ultra-high-energy-cosmic-ray facilities (e.g., the Pierre
Auger Observatory with South and North components) and TeV-gamma-ray telescope
arrays (e.g., HESS or VERITAS and CTA) have the potential to set stringent
indirect bounds on the nine Lorentz-violating parameters of nonbirefringent
modified Maxwell theory minimally coupled to standard Dirac theory.
Theoretically, the most interesting case is isotropic Lorentz violation, which
is described by a single parameter [taken to vanish for the standard
Lorentz-invariant theory]. It appears possible to obtain in the future an upper
(lower) indirect bound on this single isotropic Lorentz-violating parameter at
the +10^{-21} (-10^{-17}) level. Comparison is made with existing and future
direct bounds from laboratory experiments. The possible physics implications of
upper bounds at the 10^{-21} level are discussed.",1103.1569v2
2011-03-31,Infinite-horizon Lorentz tubes and gases: recurrence and ergodic properties,"We construct classes of two-dimensional aperiodic Lorentz systems that have
infinite horizon and are 'chaotic', in the sense that they are (Poincar\'e)
recurrent, uniformly hyperbolic, ergodic, and the first-return map to any
scatterer is $K$-mixing. In the case of the Lorentz tubes (i.e., Lorentz gases
in a strip), we define general measured families of systems (\emph{ensembles})
for which the above properties occur with probability 1. In the case of the
Lorentz gases in the plane, we define families, endowed with a natural metric,
within which the set of all chaotic dynamical systems is uncountable and dense.",1103.6110v3
2011-05-21,Distance Between Quantum Field Theories As A Measure Of Lorentz Violation,"We study the distance between symmetry-violating quantum field theories and
the surface of symmetric theories. We use this notion to quantify how precise
Lorentz symmetry is today, according to experimental data. The metric in
parameter space is defined \`a la Zamolodchikov, from the two-point function of
the Lagrangian perturbation. The distance is obtained minimizing the length of
paths connecting the Lorentz-violating theory to the Lorentz surface. This
definition depends on the Lagrangian used to formulate the theory, including
total derivatives and the choice of coordinate frame. We eliminate such
dependencies minimizing with respect to them. We derive a number of general
formulas and evaluate the distance in the CPT-invariant, QED subsectors of the
Standard Model Extension (SME) and the renormalizable
high-energy-Lorentz-violating Standard Model. We study the properties of the
distance and address a number of applications.",1105.4209v2
2011-06-30,"Comment on [arXiv:1106.1417] ""Small Lorentz violations in quantum gravity: do they lead to unacceptably large effects?""","A recent paper by Gambini, Rastgoo and Pullin [arXiv:1106.1417 investigates
the important issue of constraints from Lorentz invariance on Planck scale
physics, arguing that the classic analysis of Collins, Perez, Sudarsky, Urrutia
and Vucetich \cite{cpsuv} is not generally valid. We argue that the new work is
based on models that do not capture the relevant physics, and that almost all
models of observable high energy Lorentz violation, and proposed
Lorentz-violating theories of quantum gravity, are ruled out by low energy
tests; the only known exceptions are based on supersymmetry.",1106.6346v2
2011-08-27,Testing Lorentz Invariance Using an Odd-Parity Asymmetric Optical Resonator,"We present the first experimental test of Lorentz invariance using the
frequency difference between counter-propagating modes in an asymmetric
odd-parity optical resonator. This type of test is $\sim10^{4}$ more sensitive
to odd-parity and isotropic (scalar) violations of Lorentz invariance than
equivalent conventional even-parity experiments due to the asymmetry of the
optical resonator. The disadvantages of odd parity resonators have been negated
by the use of counter-propagating modes, delivering a high level of immunity to
environmental fluctuations. With a non-rotating experiment our result limits
the isotropic Lorentz violating parameter $\tilde{\kappa}_{tr}$ to 3.4 $\pm$
6.2 x $10^{-9}$, the best reported constraint from direct measurements. Using
this technique the bounds on odd-parity and scalar violations of Lorentz
invariance can be improved by many orders of magnitude.",1108.5414v1
2012-07-04,Quantum superpositions of the speed of light,"While it has often been proposed that, fundamentally, Lorentz-invariance is
not respected in a quantum theory of gravity, it has been difficult to
reconcile deviations from Lorentz-invariance with quantum field theory. The
most commonly used mechanisms either break Lorentz-invariance explicitly or
deform it at high energies. However, the former option is very tightly
constrained by experiment already, the latter generically leads to problems
with locality. We show here that there exists a third way to integrate
deviations from Lorentz-invariance into quantum field theory that circumvents
the problems of the other approaches. The way this is achieved is an extension
of the standard model in which photons can have different speeds without
singling out a preferred restframe, but only as long as they are in a quantum
superposition. Once a measurement has been made, observables are subject to the
laws of special relativity, and the process of measurement introduces a
preferred frame. The speed of light can take on different values, both
superluminal and subluminal (with respect to the usual value of the speed of
light), without the need for Lorentz-invariance violating operators and without
tachyons. We briefly discuss the relation to deformations of special relativity
and phenomenological consequences.",1207.1002v1
2012-09-03,Testing Lorentz invariance of dark matter,"We study the possibility to constrain deviations from Lorentz invariance in
dark matter (DM) with cosmological observations. Breaking of Lorentz invariance
generically introduces new light gravitational degrees of freedom, which we
represent through a dynamical timelike vector field. If DM does not obey
Lorentz invariance, it couples to this vector field. We find that this coupling
affects the inertial mass of small DM halos which no longer satisfy the
equivalence principle. For large enough lumps of DM we identify a (chameleon)
mechanism that restores the inertial mass to its standard value. As a
consequence, the dynamics of gravitational clustering are modified. Two
prominent effects are a scale dependent enhancement in the growth of large
scale structure and a scale dependent bias between DM and baryon density
perturbations. The comparison with the measured linear matter power spectrum in
principle allows to bound the departure from Lorentz invariance of DM at the
per cent level.",1209.0464v1
2012-09-26,Electrodynamics without Lorentz force,"This communication is devoted to a brief historical framework and to a
comprehensive critical discussion concerning foundational issues of
Electrodynamics. Attention is especially focused on the events which, about the
end of XIX century, led to the notion of Lorentz force, still today ubiquitous
in literature on Electrodynamics. Is this a noteworthy instance of a rule
which, generated by an improper simplification of Maxwell-JJ Thomson
formulation, is in fact physically untenable but, this notwithstanding, highly
successful. Modelling of electromagnetic fields and fluxes in spacetime
respectively as even and odd spatial differential forms and the formulation of
induction laws by means of exterior and Lie derivatives, make their covariance
manifest under any smooth spacetime transformations, contrary to the usual
affirmation in literature which confines this property to relativistic
frame-changes. A remarkable consequence is that there is no entanglement
between electric and magnetic fields and fluxes under special relativity
transformations. In particular, relativistic support to Lorentz force rule is
thus deactivated. For translational motions of charged bodies immersed in a
uniform and constant magnetic field, the induced electric field in such a
frame, is equal to one half the Lorentz force term. The qualitative successful
application of the Lorentz force rule to experimental evidence of special
observers is therefore explained.",1209.5960v3
2012-10-31,Lorentz Covariant Lattice Gauge Theory,"Lattice gauge theory's discretization of spacetime suffers from a drawback in
that Lorentz covariance is lost because the axes of the lattice create
preferred directions in spacetime. Smaller and smaller lattice spacings
decrease the effect but fail to eliminate it completely. It has been argued
recently that detecting such a set of preferred directions or similar
constraints would indicate whether the universe itself has an underlying
lattice, i.e. the digital universe hypothesis. In this paper, I demonstrate a
technique for accomplishing lattice gauge theory simulations while maintaining
exact Lorentz covariance by replacing the lattice with a lattice graph such
that the metric is defined as a discrete, Lorentz covariant matrix potential
over the graph rather than a metric over an underlying manifold. This technique
eliminates the symmetry violation of standard lattice gauge theory and suggests
that, even in a digital universe, Lorentz covariance can still hold.",1210.8348v1
2012-11-29,Testing Lorentz invariance with neutrino bursts from supernova neutronization,"Quantum-gravity (QG) effects might generate Lorentz invariance violation by
the interaction of energetic particles with the foamy structure of the
space-time. As a consequence, particles may not travel at the universal speed
of light. We propose to constrain Lorentz invariance violation for energetic
neutrinos exploiting the $\nu_e$ neutronization burst from the next galactic
supernova (SN). This prompt signal is expected to produce a sharp peak in the
SN $\nu_e$ light curve with a duration of $\sim 25$ ms. However presence of
energy-dependent Lorentz invariance violation would significantly spread out
the time structure of this signal. We find that the detection the SN $\nu_e$
burst from a typical galactic explosion at $d=10$ kpc in a Mton-class water
Cerenkov detector, would be sensitive to a quantum-gravity mass scale $M_{\rm
QG} \sim 10^{12}$ GeV ($2 \times10^{5}$ GeV) for the linear (quadratic) energy
dependence of Lorentz invariance violation. These limits are rather independent
of the neutrino mass hierarchy and whether the neutrino velocity is super or
subluminal.",1211.7069v2
2012-12-08,Effect of bulk Lorentz violation on anisotropic brane cosmologies,"The effect of Lorentz invariance violation in cosmology has attracted a
considerable amount of attention. By using a dynamical vector field assumed to
point in the bulk direction, with Lorentz invariance holding on the brane, we
extend the notation of Lorentz violation in four dimensions to a
five-dimensional brane-world. We obtain the general solution of the field
equations in an exact parametric form for Bianchi type I space-time, with
perfect fluid as a matter source. We show that the brane universe evolves from
an isotropic/anisotropic state to an isotropic de Sitter inflationary phase at
late time. The early time behavior of anisotropic brane universe is largely
dependent on the Lorentz violating parameters $\beta_i, i = 1, 2, 3$ and the
equation of state of the matter, while its late time behavior is independent of
these parameters.",1212.1809v2
2013-01-31,Novel Analysis of Spinor Interactions and non-Riemannian Geometry,"A novel analysis of the gauge theory of the local Lorentz group is
implemented both in flat and in curved space-time, and the resulting dynamics
is analyzed in view of the geometrical interpretation of the gauge potential.
The Yang-Mills picture of local Lorentz transformations is first approached in
a second-order formalism. For the Lagrangian approach to reproduce the second
Cartan structure equation as soon as the Lorentz gauge connections are
identified with the contortion tensor, an interaction term between the Lorentz
gauge fields and the spin connections has to be postulated. The full picture
involving gravity, torsion and spinors is described by a coupled set of field
equations, which allows one to interpret both gravitational spin connections
and matter spin density as the source term for the Yang-Mills equations. The
contortion tensor acquires a propagating character, because of its non-Abelian
feature, and the pure contact interaction is restored in the limit of vanishing
Lorentz connections.",1301.7708v3
2013-02-12,Lorentz violation in neutron and allowed nuclear beta decay,"We explore the possibility that the weak interaction violates Lorentz, and in
particular rotational, invariance in neutron and allowed nuclear beta decay. A
broad class of Lorentz-violating effects is considered, in which the standard
propagator of the W-boson acquires an additional Lorentz-violating tensor. The
general decay rate for allowed beta decay that incorporates such a modified
propagator is derived. The resulting Lorentz-violating signals are discussed
for the different types of beta-decay transitions, Fermi, Gamow-Teller, and
mixed. We study the implications of our formalism for dedicated beta-decay
experiments. We give a short overview of the few relevant experiments that have
been performed or are ongoing.",1302.2730v3
2013-03-02,"Energy Positivity, Non-Renormalization, and Holomorphy in Lorentz-Violating Supersymmetric Theories","This paper shows that the positive-energy and non-renormalization theorems of
traditional supersymmetry survive the addition of Lorentz violating
interactions. The Lorentz-violating coupling constants in theories using the
construction of Berger and Kostelecky must obey certain constraints in order to
preserve the positive energy theorem. Seiberg's holomorphic arguments are used
to prove that the superpotential remains non-renormalized (perturbatively) in
the presence of Lorentz-violating interactions of the Berger-Kostelecky type.
We briefly comment on Lorentz-violating theories of the type constructed by
Nibbelink and Pospelov to note that holomorphy arguments offer elegant proofs
of many non-renormalization results, some known by other arguments, some new.",1303.0335v3
2013-04-21,Tests of Lorentz invariance: a 2013 update,"We present an updated review of Lorentz invariance tests in Effective field
theories (EFT) in the matter as well as in the gravity sector. After a general
discussion of the role of Lorentz invariance and a derivation of its
transformations along the so called von Ignatovski theorem, we present the
dynamical frameworks developed within local EFT and the available constraints
on the parameters governing the Lorentz breaking effects. In the end, we
discuss two specific examples, the OPERA ""affaire"" and the case of
Ho\v{r}ava-Lifshitz gravity. The first case will serve as an example, and a
caveat, of the practical application of the general techniques developed for
constraining Lorentz invariance violation (LIV) to a direct observation
potentially showing these effects. The second case will show how the
application of the same techniques to a specific quantum gravity scenario has
far fetching implications not foreseeable in a purely phenomenological EFT
approach.",1304.5795v3
2013-06-05,Lorentz-Conformal Transformations in the Plane,"While conformal transformations of the plane preserve Laplace's equation,
Lorentz-conformal mappings preserve the wave equation. We discover how simple
geometric objects, such as quadrilaterals and pairs of crossing curves, are
transformed under nonlinear Lorentz-conformal mappings. Squares are transformed
into curvilinear quadrilaterals where three sides determine the fourth by a
geometric ""rectangle rule,"" which can be expressed also by functional formulas.
There is an explicit functional degree of freedom in choosing the mapping
taking the square to a given quadrilateral. We characterize classes of
Lorentz-conformal maps by their symmetries under subgroups of the dihedral
group of order eight. Unfoldings of non-invertible mappings into invertible
ones are reflected in a change of the symmetry group. The questions are simple;
but the answers are not obvious, yet have beautiful geometric, algebraic, and
functional descriptions and proofs. This is due to the very simple form of
nonlinear Lorentz-conformal transformations in dimension 1+1, provided by
characteristic coordinates.",1306.1162v2
2013-06-08,Very Special Relativity and Lorentz Violating Theories,"Very special relativity (VSR) keeps the main features of special relativity
but breaks rotational invariance. It can not be regarded as a fundamental
symmetry of nature because many observed phenomena depend on the existence of
Lorentz boosts. However, within the scope of Lorentz violating theories it can
have a role since it is breaking Lorentz symmetry in a very mild way. In this
context, when VSR terms are incorporated in a Lorentz invariant theory several
possibilities are allowed. In order to generate such terms systematically we
start with a formulation for a spinning particle in VSR. It is then coupled
minimally to the electromagnetic field and a gyromagnetic factor is added to
give rise to a magnetic moment. In order to analyze the effects of VSR in
Thomas precession a spin vector is then proposed in terms of the spinning
particle variables. It is then found the VSR contributions to the equation
which determines the spin precession angular velocity.",1306.1941v3
2013-07-22,Testing Lorentz Symmetry with the Double Chooz Experiment,"The Double Chooz reactor-based oscillation experiment searches for an
electron antineutrino disappearance signal to investigate the neutrino mass
matrix mixing angle theta 13. Double Chooz's reported evidence for this
disappearance is generally interpreted as mass-driven mixing through this
parameter. However, the electron antineutrino candidates collected by the
experiment can also be used to search for a signature of the violation of
Lorentz invariance.
  We study the sidereal time dependence of the antineutrino signal rate and
probe Lorentz violation within the Standard-Model Extension (SME) framework. We
find that the data prefer the sidereal time independent solution, and a number
of limits are applied to the relevant SME coefficients, including the first
constraints on those associated with Lorentz violation in the e-tau mixing
sector.",1307.5805v2
2013-10-31,Quantum field theory based on birefringent modified Maxwell theory,"In the current paper the properties of a birefringent Lorentz-violating
extension of quantum electrodynamics is considered. The theory results from
coupling modified Maxwell theory, which is a CPT-even Lorentz-violating
extension of the photon sector, to a Dirac theory of standard spin-1/2
particles. It is then restricted to a special birefringent case with one
nonzero Lorentz-violating coefficient. The modified dispersion laws of
electromagnetic waves are obtained plus their phase and group velocities are
considered. After deriving the photon propagator and the polarization vectors
for a special momentum configuration we prove both unitarity at tree-level and
microcausality for the quantum field theory based on this Lorentz-violating
modification. These analytical proofs are done for a spatial momentum with two
vanishing components and the proof of unitarity is supported by numerical
investigations in case all components are nonvanishing. The upshot is that the
theory is well-behaved within the framework of our assumptions where there is a
possible issue for negative Lorentz-violating coefficients. The paper shall
provide a basis for the future analysis of alternative birefringent quantum
field theories.",1311.0032v3
2014-01-10,Exploration of Lorentz violation in neutral-kaon decay,"The KLOE collaboration recently reported bounds on the directional dependence
of the lifetime of the short-lived neutral kaon $K^0_S$ with respect to the
dipole anisotropy of the cosmic microwave background. We interpret their
results in an effective field theory framework developed to probe the violation
of Lorentz invariance in the weak interaction and previously applied to
semileptonic processes, in particular $\beta$ decay. In this approach a general
Lorentz-violating tensor $\chi^{\mu\nu}$ is added to the standard propagator of
the $W$ boson. We perform an exploratory study of the prospects to search for
Lorentz violation in nonleptonic decays. For the kaon, we find that the
sensitivity to Lorentz violation is limited by the velocity of the kaons and by
the extent to which hadronic effects can be calculated. In a simple model we
derive the $K^0_S$ decay rate and calculate the asymmetry for the lifetime.
Using the KLOE data, limits on the values of $\chi^{\mu\nu}$ are determined.",1401.2245v1
2014-04-23,Lorentz Invariance in Chiral Kinetic Theory,"We show that Lorentz invariance is realized nontrivially in the classical
action of a massless spin-$\frac12$ particle with definite helicity. We find
that the ordinary Lorentz transformation is modified by a shift orthogonal to
the boost vector and the particle momentum. The shift ensures angular momentum
conservation in particle collisions and implies a nonlocality of the collision
term in the Lorentz-invariant kinetic theory due to side jumps. We show that
2/3 of the chiral-vortical effect for a uniformly rotating particle
distribution can be attributed to the magnetic moment coupling required by the
Lorentz invariance. We also show how the classical action can be obtained by
taking the classical limit of the path integral for a Weyl particle.",1404.5963v1
2014-07-13,The wave equation in the birth of spacetime symmetries,"In 1887 Voigt published a paper dedicated to the Doppler effect in which he
demanded form invariance to the wave equation in inertial frames and obtained a
set of spacetime transformations now known as the Voigt transformations. In
1905 Poincar\'e showed that the wave equation was also invariant under the
Lorentz transformations. Voigt and Lorentz transformations are then closely
related, but this relation is not widely known in the standard literature. In
this paper we derive the Lorentz transformations from the invariance of the
D'Alembert operator $\big(\Box^{2}=\Box'^{2}\big)$ and the Voigt
transformations from the conformal invariance of the D'Alembert operator
$\big(\Box^{2}=(1/\gamma^2)\Box'^{2},$ where $\gamma=1/\sqrt{1-v^2/c^2}\big).$
The homogeneous scalar wave equation is then invariant under the Lorentz
transformations and conformally invariant under the Voigt transformations. We
suggest a presentation of special relativity in which the Voigt transformations
are commented after discussing the Galilean transformations but before
presenting the Lorentz transformations.",1407.3425v2
2014-07-29,Laboratory tests of Lorentz and CPT symmetry with muons,"The prospects are explored for testing Lorentz and CPT symmetry in the muon
sector via the spectroscopy of muonium and various muonic atoms, and via
measurements of the anomalous magnetic moments of the muon and antimuon. The
effects of Lorentz-violating operators of both renormalizable and
nonrenormalizable dimensions are included. We derive observable signals,
extract first constraints from existing data on a variety of coefficients for
Lorentz and CPT violation, and estimate sensitivities attainable in forthcoming
experiments. The potential of Lorentz violation to resolve the proton radius
puzzle and the muon anomaly discrepancy is discussed.",1407.7748v2
2014-08-13,Lorentz-violating effects in three-dimensional $QED$,"Inspired in discussions presented lately regarding Lorentz-violating
interaction terms in \cite{13,6}, we propose here a slightly different version
for the coupling term. We will consider a modified quantum electrodynamics with
violation of Lorentz symmetry defined in a $\left( 2+1\right) $-dimensional
spacetime. We define the Lagrangian density with a Lorentz-violating
interaction, where the the spacetime dimensionality is explicitly taken into
account in its definition. The work encompasses an analysis of this model at
both zero and finite-temperature, where very interesting features are known to
occur due to the spacetime dimensionality. With that in mind we expect that the
spacetime dimensionality may provide new insights about the radiative
generation of higher-derivative terms into the action, implying in a new
Lorentz-violating electrodynamics, as well the nonminimal coupling may provide
interesting implications on the thermodynamical quantities.",1408.2915v1
2014-08-20,Gupta--Bleuler's quantization of the anisotropic parity-even and CPT-even electrodynamics of standard model extension,"We have established the Gupta-Bleuler quantization of the photon belonging to
the anisotropic parity-even sector of the CPT-even and Lorentz-violating
nonbirefringent electrodynamics of the standard model extension. We first
present a rule for the Maxwell electrodynamics to be successfully quantized via
Gupta-Bleuler technique in the Lorentz gauge. Recognizing the failure of the
Gupta-Bleuler method in the Lorentz gauge, $\partial _{\mu }A^{\mu }=0$, for
this massless LV theory, we argue that Gupta-Bleuler can be satisfactorily
implemented by choosing a modified Lorentz condition, $\partial _{\mu }A^{\mu
}+\kappa ^{\mu \nu }\partial _{\mu }A_{\nu }=0$, where $\kappa ^{\mu \nu }$
represents the Lorentz-violation in photon sector. By using a plane-wave
expansion for the gauge field, whose polarization vectors are determined by
solving an eigenvalue problem, and a weak Gupta-Bleuler condition, we obtain a
positive-energy Hamiltonian in terms of annihilation and creation operators.
The field commutation relation is written in terms of modified Pauli-Jordan
functions, revealing the preservation of microcausality for sufficiently small
LV parameters.",1408.4829v1
2014-09-08,Lorentz violation and higher-derivative gravity,"In this work, we analyze a gravity model with higher derivatives including a
CPT-even Lorentz-violating term. In principle, the model could be a low-energy
limit of a Lorentz-invariant theory presenting the violation of Lorentz
symmetry as a consequence of a spontaneous symmetry-breaking mechanism if a
decoupling between the metric and the Nambu-Goldstone modes is assumed. We have
set up a convenient operator basis for the expansion of wave operators for
symmetric second-rank tensors in the presence of a background vector. By using
this set of operators, the particle content is obtained, and its consistency,
regarding the conditions for stability and unitarity, is discussed. We conclude
that this extra Lorentz noninvariant contribution is unable to address the
problems of stability and unitarity of higher-derivative gravity models.",1409.5742v1
2014-12-04,Acoustic tests of Lorentz symmetry using quartz oscillators,"We propose and demonstrate a test of Lorentz symmetry based on new, compact,
and reliable quartz oscillator technology. Violations of Lorentz invariance in
the matter and photon-sector of the standard model extension (SME) generate
anisotropies in particles' inertial masses and the elastic constants, giving
rise to measurable anisotopies in the resonance frequencies of acoustic modes
in solids. A first realization of such a ""phonon-sector"" test of Lorentz
symmetry using room-temperature SC-cut crystals provides a limit of $\tilde
c_Q^{\rm n}=(-1.8 \pm 2.2)\times 10^{-14}$\,GeV on the most weakly constrained
neutron-sector $c-$coefficient of the SME. Future experiments with cryogenic
oscillators promise significant improvements in accuracy, opening up the
potential for improved limits on Lorentz violation in the neutron, proton,
electron and photon sector.",1412.2142v4
2014-12-10,Remnant group of local Lorentz transformations in f(T) theories,"It is shown that the extended teleparallel gravitational theories, known as
f(T) theories, inherit some on shell local Lorentz invariance associated with
the tetrad field defining the spacetime structure. We discuss some enlightening
examples, such as Minkowski spacetime and cosmological
(Friedmann-Robertson-Walker and Bianchi type I) manifolds. In the first case,
we show that the absence of gravity reveals itself as an incapability in the
selection of a preferred parallelization at a local level, due to the fact that
the infinitesimal local Lorentz subgroup acts as a symmetry group of the frame
characterizing Minkowski spacetime. Finite transformations are also discussed
in these examples and, contrary to the common lore on the subject, we conclude
that the set of tetrads responsible for the parallelization of these manifolds
is quite vast and that the remnant group of local Lorentz transformations
includes one and two dimensional Abelian subgroups of the Lorentz group.",1412.3424v3
2015-05-28,"The O(3,2) Symmetry derivable from the Poincaré Sphere","Henri Poincar\'e formulated the mathematics of the Lorentz transformations,
known as the Poincar\'e group. He also formulated the Poincar\'e sphere for
polarization optics. It is noted that his sphere contains the symmetry of the
Lorentz group applicable to the momentum-energy four-vector of a particle in
the Lorentz-covariant world. Since the particle mass is a Lorentz-invariant
quantity, the Lorentz group does not allow its variations. However, the
Poincar\'e sphere contains the symmetry corresponding to the mass variation,
leading to the $O(3,2)$ symmetry. An illustrative calculation is given.",1505.07715v1
2015-06-01,On a relativistic scalar particle subject to a Coulomb-type potential given by Lorentz symmetry breaking effects,"The behaviour of a relativistic scalar particle in a possible scenario that
arises from the violation of the Lorentz symmetry is investigated. The
background of the Lorentz symmetry violation is defined by a tensor field that
governs the Lorentz symmetry violation out of the Standard Model Extension.
Thereby, we show that a Coulomb-type potential can be induced by Lorentz
symmetry breaking effects and bound states solutions to the Klein-Gordon
equation can be obtained. Further, we discuss the effects of this Coulomb-type
potential on the confinement of the relativistic scalar particle to a linear
confining potential by showing that bound states solutions to the Klein-Gordon
equation can also be achieved, and obtain a quantum effect characterized by the
dependence of a parameter of the linear confining potential on the quantum
numbers $\left\{n,l\right\}$ of the system.",1506.00562v1
2015-08-17,The potential of the HAWC Observatory to observe violations of Lorentz Invariance,"The framework of relativistic quantum-field theories requires Lorentz
Invariance. Many theories of quantum gravity, on the other hand, include
violations of Lorentz Invariance at small scales and high energies. This
generates a lot of interest in establishing limits on such effects, and, if
possible, observing them directly. Gamma-ray observatories provide a tool to
probe parts of the parameter space of models of Lorentz Invariance Violation
that is not accessible in terrestrial laboratories and man-made accelerators.
Transients, especially gamma-ray bursts, are a particularly promising class of
events to search for such phenomena. By combining cosmological distances with
high energy emission and short duration, emitting photons up to 30 GeV in less
than a second, one can measure the energy dependence of the speed of photons to
one part in $10^{16}$. We will discuss the potential of HAWC to detect effects
of the violation of Lorentz Invariance and place its sensitivity in the context
of existing limits.",1508.03930v1
2015-08-21,Low energy Lorentz violation from modified dispersion at high energies,"Many quantum theories of gravity propose Lorentz violating dispersion
relations of the form $\omega = |k|\, f(|k|/M)$, with recovery of approximate
Lorentz invariance at energy scales much below $M$. We show that a quantum
field with this dispersion predicts drastic low energy Lorentz violation in
atoms modelled as Unruh-DeWitt detectors, for any $f$ that dips below unity
somewhere. As an example, we show that polymer quantization motivated by loop
quantum gravity predicts such Lorentz violation below current ion collider
rapidities.",1508.05338v2
2015-11-02,Horizons and free path distributions in quasiperiodic Lorentz gases,"We study the structure of quasiperiodic Lorentz gases, i.e., particles
bouncing elastically off fixed obstacles arranged in quasiperiodic lattices. By
employing a construction to embed such structures into a higher dimensional
periodic hyperlattice, we give a simple and efficient algorithm for numerical
simulation of the dynamics of these systems. This same construction shows that
quasiperiodic Lorentz gases generically exhibit a regime with infinite horizon,
that is, empty channels through which the particles move without colliding,
when the obstacles are small enough; in this case, the distribution of free
paths is asymptotically a power law with exponent -3, as expected from
infinite-horizon periodic Lorentz gases. For the critical radius at which these
channels disappear, however, a new regime with locally-finite horizon arises,
where this distribution has an unexpected exponent of -5, previously observed
only in a Lorentz gas formed by superposing three incommensurable periodic
lattices in the Boltzmann-Grad limit where the radius of the obstacles tends to
zero.",1511.00340v1
2016-07-05,Lorentz invariant CPT breaking in the Dirac equation,"If one modifies the Dirac equation in momentum space to
$[\gamma^{\mu}p_{\mu}-m-\Delta m(\theta(p_{0})-\theta(-p_{0}))
\theta(p_{\mu}^{2})]\psi(p)=0$, the symmetry of positive and negative energy
eigenvalues is lifted by $m\pm \Delta m$ for a small $\Delta m$. The mass
degeneracy of the particle and antiparticle is thus lifted in a Lorentz
invariant manner since the combinations $\theta(\pm p_{0})\theta(p_{\mu}^{2})$
with step functions are manifestly Lorentz invariant. We explain an explicit
construction of this CPT breaking term in coordinate space, which is Lorentz
invariant but non-local at a distance scale of the Planck length. The
application of this Lorentz invariant CPT breaking mechanism to the possible
mass splitting of the neutrino and antineutrino in the Standard Model is
briefly discussed.",1607.01409v1
2016-07-07,Implications of Lorentz symmetry violation on a 5D supersymmetric model,"Field models with $n$ extra spatial dimensions have a larger $SO(1,3+n)$
Lorentz symmetry which is broken down to the standard $SO(1,3)$ four
dimensional one by the compactification process. By considering Lorentz
violating operators in a $5D$ supersymmetric Wess-Zumino mo\-del, which
otherwise conserve the standard four dimensional Poincare invariance, we show
that supersymmetry can be restored upon a simple deformation of the
supersymmetric transformations. However, supersymmetry is not preserved in the
effective $4D$ theory that arises after compactification when the $5D$ Lorentz
violating operators do not preserve $Z_2: y\rightarrow -y$ bulk parity. Our
mechanism unveils a possible connection among Lorentz violation and the
Scherk-Schwarz mechanism. We also show that parity preserving models, on the
other hand, do provide well defined supersymmetric KK models.",1607.02095v2
2016-07-25,Nonminimal Lorentz-Violating Effects in Photon Physics,"We study an extension of QED involving a light pseudoscalar (an axion-like
particle), together with a very massive fermion which has Lorentz-violating
interactions with the photon and the pseudoscalar, including a nonminimal
Lorentz-violating coupling. We investigate the low energy effective action for
this model, after integration over the fermion field, and show that interesting
results are obtained, such as the generation of a correction to the standard
coupling between the axion-like particle and the photon, as well as
Lorentz-violating effects in the interaction energy involving electromagnetic
sources such as pointlike charges, steady line currents and Dirac strings.",1607.07390v1
2016-10-15,Tests of Lorentz symmetry in the gravitational sector,"Lorentz symmetry is one of the pillars of both General Relativity and the
Standard Model of particle physics. Motivated by ideas about quantum gravity,
unification theories and violations of CPT symmetry, a significant effort has
been put the last decades into testing Lorentz symmetry. This review focuses on
Lorentz symmetry tests performed in the gravitational sector. We briefly review
the basics of the pure gravitational sector of the Standard-Model Extension
(SME) framework, a formalism developed in order to systematically parametrize
hypothetical violations of the Lorentz invariance. Furthermore, we discuss the
latest constraints obtained within this formalism including analyses of the
following measurements: atomic gravimetry, Lunar Laser Ranging, Very Long
Baseline Interferometry, planetary ephemerides, Gravity Probe B, binary
pulsars, high energy cosmic rays,... In addition, we propose a combined
analysis of all these results. We also discuss possible improvements on current
analyses and present some sensitivity analyses for future observations.",1610.04682v2
2018-02-10,Large Scale Lorentz Violation Gravity and Dark Energy,"The accelerating expansion of universe can be described by the non-zero
cosmological constant or the dark energy. However, the origin of the dark
energy remains a mystery of modern physics. The local Lorentz invariance is the
most exact symmetry of the Nature on the one hand, but all quantum gravity
theories predict Lorentz violation on the other hand. The local Lorentz
violation induced by the quantum gravity at the very early universe may be
transformed into large scale by inflation. Combining the low-$l$ anomalies of
the CMB spectrum, we propose that the local Lorentz invariance may be broken at
the large scale. We construct the effective gravity at the cosmic scale with a
local $SO(3)$ symmetry. The theory exhibits non-trivial contortion distribution
even with scalar matter source. The FRW like solution of the theory is analyzed
and the contortion distribution contributes a dark energy like effect which is
responsible for the accelerating expansion of the universe. It reveals that the
dark energy may be the remnants of quantum gravity in this sense.",1802.03502v3
2018-10-29,Spinors and gravity without Lorentz indices,"Coupling spinor fields to the gravitational field, in the setting of general
relativity, is standardly done via the introduction of a vierbein field and the
(associated minimal) spin connection field. This makes three types of indices
feature in the formalism: world/coordinate indices, Lorentz vector indices, and
Lorentz spinor indices, respectively. This article will show, though, that it
is possible to dispense altogther with the Lorentz indices, both tensorial ones
and spinorial ones, obtaining a formalism featuring only world indices. This
will be possible by having both the 'Dirac operator' and the generators of
'Lorentz' transformations become spacetime-dependent, although covariantly
constant. The formalism is developed in the setting of complexified
quaternions.",1811.00377v2
2020-07-16,Growth envelopes of some variable and mixed function spaces,"We study unboundedness properties of functions belonging Lebesgue and Lorentz
spaces with variable and mixed norms using growth envelopes. Our results extend
the ones for the corresponding classical spaces in a natural way. In the case
of spaces with mixed norms it turns out that the unboundedness in the worst
direction, i.e., in the direction where $p_{i}$ is the smallest, is crucial.
More precisely, the growth envelope is given by $E_G(L_{\vec{p}}(\Omega)) =
(t^{-1/\min\{p_{1}, \ldots, p_{d} \}},\min\{p_{1}, \ldots, p_{d} \})$ for mixed
Lebesgue and $E_G(L_{\vec{p},q}(\Omega)) = (t^{-1/\min\{p_{1}, \ldots, p_{d}
\}},q)$ for mixed Lorentz spaces, respectively. For the variable Lebesgue
spaces we obtain $E_G(L_{p(\cdot)}(\Omega)) = (t^{-1/p_{-}},p_{-})$, where
$p_{-}$ is the essential infimum of $p(\cdot)$, subject to some further
assumptions. Similarly, for the variable Lorentz space it holds
$E_G(L_{p(\cdot),q}(\Omega)) = (t^{-1/p_{-}},q)$. The growth envelope is used
for Hardy-type inequalities and limiting embeddings. In particular, as a
by-product we determine the smallest classical Lebesgue (Lorentz) space which
contains a fixed mixed or variable Lebesgue (Lorentz) space, respectively.",2007.08210v2
2010-05-10,Lorentz-violating gravitoelectromagnetism,"The well-known analogy between a special limit of General Relativity and
electromagnetism is explored in the context of the Lorentz-violating
Standard-Model Extension (SME). An analogy is developed for the minimal SME
that connects a limit of the CPT-even component of the electromagnetic sector
to the gravitational sector. We show that components of the post-newtonian
metric can be directly obtained from solutions to the electromagnetic sector.
The method is illustrated with specific examples including static and rotating
sources. Some unconventional effects that arise for Lorentz-violating
electrostatics and magnetostatics have an analog in Lorentz-violating
post-newtonian gravity. In particular, we show that even for static sources,
gravitomagnetic fields arise in the presence of Lorentz violation.",1005.1435v2
2014-03-24,A note on Lorentz-like transformations and superluminal motion,"In this extended note a critical discussion of an extension of the Lorentz
transformations for velocities faster than the speed of light given recently by
Hill and Cox is provided. The presented approach reveals the connection between
faster-than-light speeds and the issue of isotropy of space. It is shown if the
relative speed between the two inertial frames $v$ is greater than the speed of
light, the condition of isotropy of space cannot be retained. It further
specifies the respective transformations applying to $-\infty<v<-c$ and
$c<v<+\infty$. It is proved that such Lorentz-like transformations are improper
transformations since the Jacobian is negative. As a consequence, the wave
operator, the light-cone and the volume element are not invariant under such
Lorentz-like transformations. Also it is shown that such Lorentz-like
transformations are not new and already known in the literature.",1403.5988v2
2016-11-06,Enhanced sensitivity to Lorentz invariance violations in short-range gravity experiments,"Recently, first limits on putative Lorentz invariance violation coefficients
in the pure gravity sector were determined by the reanalysis of short-range
gravity experiments. Such experiments search for new physics at sidereal
frequencies. They are not, however, designed to optimize the signal strength of
a Lorentz invariance violation force; in fact the Lorentz violating signal is
suppressed in the planar test mass geometry employed in those experiments. We
describe a short-range torsion pendulum experiment with enhanced sensitivity to
possible Lorentz violating signals. A periodic, striped test mass geometry is
used to augment the signal. Careful arrangement of the phases of the striped
patterns on opposite ends of the pendulum further enhances the signal while
simultaneously suppressing the Newtonian background.",1611.01770v1
2016-11-30,Constraints on violation of Lorentz invariance from atmospheric showers initiated by multi-TeV photons,"We discuss the effect of hypothetical violation of Lorentz invariance at high
energies on the formation of atmospheric showers by very-high-energy gamma
rays. In the scenario where Lorentz invariance violation leads to a decrease of
the photon velocity with energy the formation of the showers is suppressed
compared to the Lorentz invariant case. Absence of such suppression in the
high-energy part of spectrum of the Crab nebula measured independently by HEGRA
and H.E.S.S. collaborations is used to set lower bounds on the energy scale of
Lorentz invariance violation. These bounds are competitive with the strongest
existing constraints obtained from timing of variable astrophysical sources and
the absorption of TeV photons on the extragalactic background light. They will
be further improved by the next generation of multi-TeV gamma-ray
observatories.",1611.10125v2
2017-04-27,Effective potential in Lorentz-breaking field theory models,"We calculate explicitly the one-loop effective potential in different
Lorentz-breaking field theory models. First, we consider a Yukawa-like theory
and, then, some examples of Lorentz-violating extensions of scalar QED. We
observed, for the extended QED models, that the resulting effective potential
converges to the known result in the limit in which Lorentz-symmetry is
restored. Besides, the one-loop corrections to the effective potential in all
the cases we studied depend on the background tensors responsible for the
Lorentz symmetry violation. This have consequences in physical quantities like,
for example, in the induced mass due to Coleman-Weinberg mechanism.",1704.08556v3
2012-04-23,Lorentz Group in Ray and Polarization Optics,"While the Lorentz group serves as the basic language for Einstein's special
theory of relativity, it is turning out to be the basic mathematical instrument
in optical sciences, particularly in ray optics and polarization optics. The
beam transfer matrix, commonly called the $ABCD$ matrix, is shown to be a
two-by-two representation of the Lorentz group applicable to the
three-dimensional space-time consisting of two space and one time dimensions.
The Jones matrix applicable to polarization states turns out to be the
two-by-two representations of the Lorentz group applicable to the
four-dimensional space-time consisting of three space and one time dimensions.
The four-by-four Mueller matrix applicable to the Stokes parameters as well as
the Poincar\'e sphere are both shown to be the representations of the Lorentz
group.",1204.5071v1
2014-06-20,The Exact Foldy-Wouthuysen Transformation for a Dirac Theory with the complete set of CPT-Lorentz violating terms,"The exact Foldy-Wouthuysen transformation is performed in order to study the
Dirac field interacting with many possible external fields associated with
CPT-Lorentz violation. We also derived the calculation of equations of motion
as well as the generalized Lorentz force corrected by the mentioned external
fields. The main point is the interaction between the Dirac particle and the
terms that have the multiplication of electromagnetic field and the terms that
break CPT-Lorentz. Finally, with the transformed Hamiltonian we were able to
write an expression for the bound state of the theory and analyze it in the
atomic experiments context. This result is an analytical expression that gives
the possibility of the weakness of CPT/Lorentz terms to be compensated by the
presence of a strong magnetic field.",1406.5477v1
2014-06-27,Didactic derivation of the special theory of relativity from the Klein-Gordon equation,"We present a didactic derivation of the special theory of relativity in which
Lorentz transformations are `discovered' as symmetry transformations of the
Klein-Gordon equation. The interpretation of Lorentz boosts as transformations
to moving inertial reference frames is not assumed at the start, but it
naturally appears at a later stage. The relative velocity $\textbf{v}$ of two
inertial reference frames is defined in terms of the elements of the pertinent
Lorentz matrix, and the bound $|\textbf{v}| <c\;$ is obtained as a simple
theorem that follows from the structure of the Lorentz group. The polar
decomposition of Lorentz matrices is used to explain noncommutativity and
nonassociativity of the relativistic composition (`addition') of velocities.",1406.7849v2
2016-08-01,Modified Lorentz transformations in deformed special relativity,"We extend a recent approach to Deformed Special Relativity based on deformed
dispersion laws, entailing modified Lorentz transformations and, at the same
time, noncommutative geometry and intrinsically discrete spacetime. In so doing
we obtain the explicit form of the modified Lorentz transformations for a
special class of modified momentum-energy relations often found in literature
and arising from elementary particle physics. Actually, our theory looks as a
very simple and natural extension of special relativity to include a momentum
cut-off at the Planck scale. In particular, the new Lorentz transformations do
imply that for high boost speed ($V \sim c$) the deformed Lorentz factor does
not diverge as in ordinary relativity, but results to be upperly bounded by a
large finite value of the order of the ratio between the Planck mass and the
particle mass. We also predict that a generic boost leaves unchanged Planck
energy and momentum, which result invariant with respect to any reference
frame.",1608.00322v2
2016-08-11,Searches for Anisotropic Lorentz-Invariance Violation in the Photon Sector,"Lorentz invariance, the fundamental symmetry of Einstein's theory of Special
Relativity, has been established and tested by many classical and modern
experiments. However, many theories that unify the Standard Model of particle
physics and General Relativity predict a violation of Lorentz invariance at the
Planck scale. While this energy range cannot be reached by current experiments,
minute deviations from Lorentz symmetry may be present at lower energies.
Astrophysical experiments are very suitable to search for these deviations,
since their effects accumulate as photons travel across large distances. In
this paper, we describe astrophysical methods that we used to constrain the
photon dispersion and vacuum birefringence.",1608.03631v1
2016-12-05,Charged Lifshitz black hole and probed Lorentz-violation fermions from holography,"We analytically obtain a new charged Lifshtitz solution by adding a
non-relativistic Maxwell field in Horava-Lifshitz gravity. The black hole
exhibits an anisotropic scaling between space and time (Lifshitz scaling) in
the UV limit, while in the IR limit, the Lorentz invariance is recovered. We
introduce the probed Lorentz-violation fermions into the background and
holographically investigate the spectral properties of the dual fermionic
operator. The Lorentz-violation of fermions will enhance the peak and
corresponds larger fermi momentum, which compensates the non-relativistic bulk
effect of the dynamical exponent. For a fixed $z$, when the Lorentz-violation
of fermions increases to a critical value, the behavior of the low energy
excitation goes from a non-Fermi liquid type to a fermi liquid type, which
implies a kind of phase transition.",1612.01247v2
2016-12-29,Neutrino oscillations and Lorentz invariance violation,"Lorentz invariance is a well known fundamental concept of special relativity
but its violation is predicted by some variations of quantum gravity, string
theory, and some alternatives to general relativity. We study neutrino
oscillation at the presence of the Lorentz invariance violation in vacuum,
normal and nuclear media. It is shown that for very high energy neutrinos the
neutrino oscillations due to mass difference is suppressed and its contribution
to the conversion probability is negligibly small, but the contribution of the
Lorentz invariance violation term is not zero. This means that the observation
of very high energy neutrino oscillations may be a signal of the discreteness
of space and Lorentz invariance violation.",1612.09280v1
2017-10-18,Low energy Lorentz violation from high energy modified dispersion in inertial and circular motion,"We consider an Unruh-DeWitt detector in inertial and circular motion in
Minkowski spacetime of arbitrary dimension, coupled to a quantised scalar field
with the Lorentz-violating dispersion relation $\omega = |{\bf k}|\, f (|{\bf
k}|/M_{\star})$, where $M_{\star}$ is the Lorentz-breaking scale. Assuming that
$f$ dips below unity somewhere, we show that an inertial detector experiences
large low energy Lorentz violations in all spacetime dimensions greater than
two, generalising previous results in four dimensions. For a detector in
circular motion, we show that a similar low energy Lorentz violation occurs in
three spacetime dimensions, and we lay the analytic groundwork for examining
circular motion in all dimensions greater than three, generalising previous
work by Stargen, Kajuri and Sriramkumar in four dimensions. The circular motion
results may be relevant for the prospects of observing the circular motion
Unruh effect in analogue laboratory systems.",1710.06954v4
2017-12-03,Hadronic Lorentz Violation in Chiral Perturbation Theory Including the Coupling to External Fields,"If any violation of Lorentz symmetry exists in the hadron sector, its
ultimate origins must lie at the quark level. We continue the analysis of how
the theories at these two levels are connected, using chiral perturbation
theory. Considering a two-flavor quark theory, with dimension-4 operators that
break Lorentz symmetry, we derive a low-energy theory of pions and nucleons
that is invariant under local chiral transformations and includes the coupling
to external fields. The pure meson and baryon sectors, as well as the couplings
between them and the couplings to external electromagnetic and weak gauge
fields, contain forms of Lorentz violation which depend on linear combinations
of quark-level coefficients. In particular, at leading order the
electromagnetic couplings depend on the very same combinations as appear in the
free particle propagators. This means that observations of electromagnetic
processes involving hadrons--such as vacuum Cerenkov radiation, which may be
allowed in Lorentz-violating theories--can only reliably constrain certain
particular combinations of quark coefficients.",1712.00838v2
2018-09-13,Resolving the Weinberg Paradox with Topology,"Long ago Weinberg showed, from first principles, that the amplitude for a
single photon exchange between an electric current and a magnetic current
violates Lorentz invariance. The obvious conclusion at the time was that
monopoles were not allowed in quantum field theory. Since the discovery of
topological monopoles there has thus been a paradox. On the one hand,
topological monopoles are constructed in Lorentz invariant quantum field
theories, while on the other hand, the low-energy effective theory for such
monopoles will reproduce Weinberg's result. We examine a toy model where both
electric and magnetic charges are perturbatively coupled and show how
soft-photon resummation for hard scattering exponentiates the Lorentz violating
pieces to a phase that is the covariant form of the Aharonov-Bohm phase due to
the Dirac string. The modulus of the scattering amplitudes (and hence
observables) are Lorentz invariant, and when Dirac charge quantization is
imposed the amplitude itself is also Lorentz invariant. For closed paths there
is a topological component of the phase that relates to aspects of 4D
topological quantum field theory.",1809.05102v2
2019-06-13,Homogeneously Modified Special Relativity (HMSR) -- A new possible way to introduce an isotropic Lorentz Invariance Violation in particle Standard Model,"This work explores a Standard Model (S.M.) extension possibility, that
violates Lorentz invariance, preserving the space-time isotropy and
homogeneity. In this sense HMSR represents an attempt to introduce an isotropic
Lorentz Invariance Violation in the elementary particle S.M. The theory is
constructed starting from a modified kinematics, that takes into account
supposed quantum effects due to interaction with the space-time background. The
space-time structure itself is modified, resulting in a pseudo-Finsler
manifold. The S.M. extension here provided is inspired by the effective fields
theories, but it preserves covariance, with respect to newly introduced
modified Lorentz transformations. Geometry perturbations are not considered as
universal, but particle species dependent. Non universal character of the
amended Lorentz transformations allows to obtain visible physical effects,
detectable in experiments by comparing different perturbations related to
different interacting particles species.",1906.05595v3
2019-09-23,Neutron Star Structure in the Minimal Gravitational Standard-Model Extension and the Implication to Continuous Gravitational Waves,"Tiny violation of Lorentz invariance has been the subject of theoretic study
and experimental test for a long time. We use the Standard-Model Extension
(SME) framework to investigate the effect of the minimal Lorentz violation on
the structure of a neutron star. A set of hydrostatic equations with
modifications from Lorentz violation are derived, and then the modifications
are isolated and added to the Tolman-Oppenheimer-Volkoff (TOV) equation as the
leading-order Lorentz-violation corrections in relativistic systems. A
perturbation solution to the leading-order modified TOV equations is found. The
quadrupole moments due to the anisotropy in the structure of neutron stars are
calculated and used to estimate the quadrupole radiation of a spinning neutron
star with the same deformation. The calculation puts forward a new test for
Lorentz invariance in the strong-field regime when continuous gravitational
waves are observed in the future.",1909.10372v2
2019-09-24,Formal Developments for Lorentz-Violating Dirac Fermions and Neutrinos,"The current paper is a technical work that is focused on Lorentz violation
for Dirac fermions as well as neutrinos, described within the nonminimal
Standard-Model Extension. We intend to derive two theoretical results. The
first is the full propagator of the single-fermion Dirac theory modified by
Lorentz violation. The second is the dispersion equation for a theory of $N$
neutrino flavors that enables the description of both Dirac and Majorana
neutrinos. As the matrix structure of the neutrino field operator is very
involved for generic $N$, we will use sophisticated methods of linear algebra
to achieve our objectives. Our main finding is that the neutrino dispersion
equation has the same structure in terms of Lorentz-violating operators as that
of a modified single-fermion Dirac theory. The results will be valuable for
phenomenological studies of Lorentz-violating Dirac fermions and neutrinos.",1909.11061v1
2020-12-02,Precession of spheroids under Lorentz violation and observational consequences for neutron stars,"The Standard-Model Extension (SME) is an effective-field-theoretic framework
that catalogs all Lorentz-violating field operators. The anisotropic correction
from the minimal gravitational SME to Newtonian gravitational energy for
spheroids is studied, and the rotation of rigid spheroids is solved with
perturbation method and numerical approach. The well-known forced precession
solution given by Nordtvedt in the parameterized post-Newtonian formalism is
recovered and applied to two observed solitary millisecond pulsars to set
bounds on the coefficients for Lorentz violation in the SME framework. A
different solution, which describes the rotation of an otherwise
free-precessing star in the presence of Lorentz violation, is found, and its
consequences on pulsar signals and continuous gravitational waves (GWs) emitted
by neutron stars (NSs) are investigated. The study provides new possible tests
of Lorentz violation once free-precessing NSs are firmly identified in the
future.",2012.01320v3
2012-05-29,Geometrical approach to the proton spin decomposition,"We discuss in detail and from the geometrical point of view the issues of
gauge invariance and Lorentz covariance raised by the approach proposed
recently by Chen et al. to the proton spin decomposition. We show that the
gauge invariance of this approach follows from a mechanism similar to the one
used in the famous Stueckelberg trick. Stressing the fact that the Lorentz
symmetry does not force the gauge potential to transform as a Lorentz
four-vector, we show that the Chen et al. approach is Lorentz covariant
provided that one uses the suitable Lorentz transformation law. We also make an
attempt to summarize the present situation concerning the proton spin
decomposition. We argue that the ongoing debates concern essentially the
physical interpretation and are due to the plurality of the adopted pictures.
We discuss these different pictures and propose a pragmatic point of view.",1205.6483v2
2017-05-15,Anisotropic Variable Hardy-Lorentz Spaces and Their Real Interpolation,"Let $p(\cdot):\ \mathbb R^n\to(0,\infty)$ be a variable exponent function
satisfying the globally log-H\""{o}lder continuous condition, $q\in(0,\infty]$
and $A$ be a general expansive matrix on $\mathbb{R}^n$. In this article, the
authors first introduce the anisotropic variable Hardy-Lorentz space
$H_A^{p(\cdot),q}(\mathbb R^n)$ associated with $A$, via the radial grand
maximal function, and then establish its radial or non-tangential maximal
function characterizations. Moreover, the authors also obtain characterizations
of $H_A^{p(\cdot),q}(\mathbb R^n)$, respectively, in terms of the atom and the
Lusin area function. As an application, the authors prove that the anisotropic
variable Hardy-Lorentz space $H_A^{p(\cdot),q}(\mathbb R^n)$ severs as the
intermediate space between the anisotropic variable Hardy space
$H_A^{p(\cdot)}(\mathbb R^n)$ and the space $L^\infty(\mathbb R^n)$ via the
real interpolation. This, together with a special case of the real
interpolation theorem of H. Kempka and J. Vyb\'iral on the variable Lorentz
space, further implies the coincidence between $H_A^{p(\cdot),q}(\mathbb R^n)$
and the variable Lorentz space $L^{p(\cdot),q}(\mathbb R^n)$ when
$\mathop\mathrm{essinf}_{x\in\mathbb{R}^n}p(x)\in (1,\infty)$.",1705.05188v1
2017-05-17,Minimal Lorentz Surfaces in Pseudo-Euclidean 4-Space with Neutral Metric,"We study minimal Lorentz surfaces in the pseudo-Euclidean 4-space with
neutral metric whose first normal space is two-dimensional and whose Gauss
curvature $K$ and normal curvature $\varkappa$ satisfy the inequality
$K^2-\varkappa^2 >0$. Such surfaces we call minimal Lorentz surfaces of general
type. On any surface of this class we introduce geometrically determined
canonical parameters and prove that any minimal Lorentz surface of general type
is determined (up to a rigid motion) by two invariant functions satisfying a
system of two natural partial differential equations. Using a concrete solution
to this system we construct an example of a minimal Lorentz surface of general
type.",1705.06151v3
2017-05-30,$M$-ideal properties in Orlicz-Lorentz spaces,"We provide explicit formulas for the norm of bounded linear functionals on
Orlicz-Lorentz function spaces $\Lambda_{\varphi,w}$ equipped with two standard
Luxemburg and Orlicz norms. Any bounded linear functional is a sum of regular
and singular functionals, and we show that the norm of a singular functional is
the same regardless of the norm in the space, while the formulas of the norm of
general functionals are different for the Luxemburg and Orlicz norm. The
relationship between equivalent definitions of the modular $P_{\varphi,w}$
generating the dual space to Orlicz-Lorentz space is discussed in order to
compute the norm of a bounded linear functional on $\Lambda_{\varphi,w}$
equipped with Orlicz norm. As a consequence, we show that the order-continuous
subspace of Orlicz-Lorentz space equipped with the Luxemburg norm is an
$M$-ideal in $\Lambda_{\varphi,w}$, while this is not true for the space with
the Orlicz norm when $\varphi$ is an Orlicz $N$-function not satisfying the
appropriate $\Delta_2$ condition. The analogous results on Orlicz-Lorentz
sequence spaces are given.",1705.10451v2
2017-09-04,Anomalous Lorentz and CPT violation,"If there exists Lorentz and CPT violation in nature, then it is crucial to
discover and understand the underlying mechanism. In this contribution, we
discuss one such mechanism which relies on four-dimensional chiral gauge
theories defined over a spacetime manifold with topology $\mathbb{R}^3 \times
S^1$ and periodic spin structure for the compact dimension. It can be shown
that the effective gauge-field action contains a local Chern-Simons-like term
which violates Lorentz and CPT invariance. For arbitrary Abelian $U(1)$ gauge
fields with trivial holonomies in the compact direction, this anomalous Lorentz
and CPT violation has recently been established perturbatively with a
Pauli-Villars-type regularization and nonperturbatively with a lattice
regularization based on Ginsparg-Wilson fermions.",1709.01004v4
2018-02-28,Critical properties of scalar field theory with Lorentz violation: Exact treatment of Lorentz-violating mechanism,"In this work, we compute analytically the infrared divergences of massless
O($N$) self-interacting scalar field theories with Lorentz violation, which are
exact in the Lorentz-violating $K_{\mu\nu}$ coefficients, for evaluating the
corresponding next-to-leading order critical exponents. For that, we apply
three distinct and independent field-theoretic renormalization group methods.
We find that the outcomes for the critical exponents are the same in the three
methods and, furthermore, are identical to their Lorentz invariant
counterparts. We generalize the results for all loop levels by employing a
general theorem arising from the exact procedure and give the corresponding
physical interpretation.",1803.00069v1
2018-06-15,Understanding the electromagnetic 4-potential in the tetrad bundle,"Separation of the spin and orbital angular momenta of the electromagnetic
field has been discussed frequently in recent years. The spin and orbital
angular momenta cannot be made simultaneously gauge invariant and Lorentz
covariant and are not conserved separately. After analyzing the source of the
problem, we find that the electromagnetic 4-potential depends on the local
reference frame instead of the global reference frame. The transformation of
the local reference frame is the intrinsic degree of freedom of the
electromagnetic field. Therefore, considering only the Lorentz transformation
of the global reference frame and neglecting the Lorentz transformation of the
local reference frame may lead to the noncovariance of the electromagnetic
4-potential. Accordingly, we redescribe these difficulties of the
electromagnetic field from the perspective of quantum field theory. By using
the behavior of the electromagnetic 4-potential that satisfies the Coulomb
gauge in Lorentz coordinate transformation, we can construct the
electromagnetic vector in the tetrad bundle. The various physical quantities
that are induced by this electromagnetic vector satisfy Lorentz covariance in
the tetrad bundle. This electromagnetic vector, which is projected onto
space-time, is an electromagnetic 4-potential that satisfies the Coulomb gauge;
thus, the electromagnetic vector is gauge invariant.",1806.07236v2
2018-08-16,Is there any symmetry left in gravity theories with explicit Lorentz violation?,"It is well known that a theory with explicit Lorentz violation is not
invariant under diffeomorphisms. On the other hand, for geometrical theories of
gravity, there are alternative transformations, which can be best defined
within the first-order formalism, and that can be regarded as a set of improved
diffeomorphisms. These symmetries are known as local translations and, among
other features, they are Lorentz covariant off shell. It is thus interesting to
study if theories with explicit Lorentz violation are invariant under local
translations. In this work, an example of such a theory, known as the minimal
gravity sector of the Standard Model Extension, is analyzed. Using a robust
algorithm, it is shown that local translations are not a symmetry of the
theory. It remains to be seen if local translations are spontaneously broken
under spontaneous Lorentz violation, which are regarded as a more natural
alternative when spacetime is dynamic.",1808.05522v2
2019-01-06,Topological thermal Hall effect for topological excitations in spin liquid: Emergent Lorentz force on the spinons,"We study the origin of Lorentz force on the spinons in a U(1) spin liquid. We
are inspired by the previous observation of gauge field correlation in the
pairwise spin correlation using the neutron scattering measurement when the
Dzyaloshinskii-Moriya interaction intertwines with the lattice geometry. We
extend this observation to the Lorentz force that exerts on the (neutral)
spinons. The external magnetic field, that polarizes the spins, effectively
generates an internal U(1) gauge flux for the spinons and twists the spinon
motion through the Dzyaloshinskii-Moriya interaction. Such a mechanism for the
emergent Lorentz force differs fundamentally from the induction of the internal
U(1) gauge flux in the weak Mott insulating regime from the charge
fluctuations. We apply this understanding to the specific case of spinon metals
on the kagome lattice. Our suggestion of emergent Lorentz force generation and
the resulting topological thermal Hall effect may apply broadly to other
non-centrosymmetric spin liquids with Dzyaloshinskii-Moriya interaction. We
discuss the relevance with the thermal Hall transport in kagome materials
volborthite and kapellasite.",1901.01522v2
2019-01-12,Unimodular gravity theory with external sources in a Lorentz-symmetry breaking scenario,"This paper is dedicated to the study of interactions between stationary field
sources for the linearized unimodular gravity or WTDIFF theory in a model which
exhibits Lorentz symmetry breaking due to the presence of the linearized
topological Chern-Simons term in $3 + 1$ dimensions, where the Lorentz symmetry
breaking is caused by a single background vector $v^{\mu}$. Since the
background vector is very tiny, we treat it perturbatively up to second order
and we focus on physical phenomena which have no counterpart in standard WTDIFF
theory. We consider effects related to field sources describing point-like
particles and cosmic strings. We show that in a Lorentz violating scenario the
interaction between external sources lead to numerically different results for
linerarized Eintein-Hilbert (LEH) and WTDIFF theories, however both results are
qualitatively similar and can be equalized after a rescaling of the Lorentz
breaking source term which makes an experimental distinction impossible at
leading order in pertubation theory as far as point particles and cosmic
strings are concerned.",1901.03914v1
2019-02-22,On Lorentz violation in $e^{-}\!\!+\!e^{+}\!\rightarrow\!μ^{-}\!\!+\!μ^{+}$ scattering at finite temperature,"Small violation of Lorentz and CPT symmetries may emerge in models unifying
gravity with other forces of nature. An extension of the standard model with
all possible terms that violate Lorentz and CPT symmetries are included. Here a
CPT-even non-minimal coupling term is added to the covariant derivative. This
leads to a new interaction term that breaks the Lorentz symmetry. Our main
objective is to calculate the cross section for the
$e^{-}\!\!+\!e^{+}\!\rightarrow\!\mu^{-}\!\!+\!\mu^{+}$ scattering in order to
investigate any violation of Lorentz and/or CPT symmetry at finite temperature.
Thermo Field Dynamics formalism is used to consider finite temperature effects.",1902.08402v1
2019-03-03,Two series of polyhedral fundamental domains for Lorentz bi-quotients,"The main aim of this paper is to give two infinite series of examples of
Lorentz space forms that can be obtained from Lorentz polyhedra by
identification of faces. These Lorentz space forms are bi-quotients of the form
$\Gamma_1\backslash G/\Gamma_2$, where
$G=\widetilde{\operatorname{SU}(1,1)}\cong\widetilde{\operatorname{SL}(2,{\mathbb
R})}$ is a simply connected Lie group with the Lorentz metric given by the
Killing form, $\Gamma_1$ and $\Gamma_2$ are discrete subgroups of $G$ and
$\Gamma_2$ is cyclic. A construction of polyhedral fundamental domains for the
action of $\Gamma_1\times\Gamma_2$ on $G$ via $(g,h)\cdot x=gxh^{-1}$ was given
in the earlier work of the second author. In this paper we give an explicit
description of the fundamental domains obtained by this construction for two
infinite series of groups. These results are connected to singularity theory as
the bi-quotients $\Gamma_1\backslash G/\Gamma_2$ appear as links of certain
quasi-homogeneous $\mathbb Q$-Gorenstein surface singularities, i.e.\ the
intersections of the singular variety with sufficiently small spheres around
the isolated singular point.",1903.01011v2
2019-03-12,Classical Lagrangians for the nonminimal Standard-Model Extension at higher orders in Lorentz violation,"The current paper is dedicated to determining perturbative expansions for
Lagrangians describing classical, relativistic, pointlike particles subject to
Lorentz violation parameterized by the nonminimal Standard-Model Extension
(SME). An iterative technique recently developed and applied to a
Lorentz-violating scalar field theory is now adopted to treat the
spin-degenerate SME fermion sector. Lagrangians are obtained at third order in
Lorentz violation for the operators $\hat{a}_{\mu}$, $\hat{c}_{\mu}$,
$\hat{e}$, $\hat{f}$, and $\hat{m}$ for arbitrary mass dimension. The results
demonstrate the impact of nonzero spin on classical particle propagation. They
will be useful for phenomenological studies of modified gravity and could
provide useful insights into explicit Lorentz violation in curved spacetimes.",1903.05064v1
2019-11-10,Lorentz and CPT Violation in Partons,"A framework is presented for the factorization of high-energy hadronic
processes in the presence of Lorentz and CPT violation. The comprehensive
effective field theory describing Lorentz and CPT violation, the Standard-Model
Extension, is used to demonstrate factorization of the hadronic tensor at
leading order in electroweak interactions for deep inelastic scattering and for
the Drell-Yan process. Effects controlled by both minimal and nonminimal
coefficients for Lorentz violation are explored, and the equivalent
parton-model description is derived. The methodology is illustrated by
determining cross sections and studying estimated attainable sensitivities to
Lorentz violation using real data collected at the Hadronen-Elektronen Ring
Anlage and the Large Hadron Collider and simulated data for the future US-based
electron-ion collider.",1911.04002v2
2019-12-06,Lorentz Symmetry Violation in QCD and the Frustration of Asymptotic Freedom,"We study the effect of Lorentz symmetry violation (LSV) on the behaviour at
high energy of SU(N) gauge theory with quarks in the fundamental
representation. The approach is similar to that for QED treated in a previous
paper. In contrast to QED, standard Lorentz invariant QCD is asymptotically
free. Our aim is to explore the structure of the renormalisation group at high
energy and hence weak coupling without requiring the Lorentz symmetry breaking
to be small. The simplest type of LSV leaves the theory invariant under a
subgroup of the Lorentz group that preserves a (time-like) 4-vector. We examine
this case in detail and find that asymptotic freedom is frustrated. That is, at
sufficiently high energy the running coupling constant attains a minimum value
before increasing again, while the LSV parameter increases without bound.",1912.03087v3
2020-05-01,Casimir effect in Lorentz-violating scalar field theory: a local approach,"We study the Casimir effect in the classical geometry of two parallel
conductive plates, separated by a distance $L$, for a Lorentz-breaking
extension of the scalar field theory. The Lorentz-violating part of the theory
is characterized by the term $\lambda \left( u \cdot \partial \phi \right
)^{2}$, where the parameter $\lambda$ and the background four-vector $u ^{\mu}$
codify Lorentz symmetry violation. We use Green's function techniques to study
the local behavior of the vacuum stress-energy tensor in the region between the
plates. Closed analytical expressions are obtained for the Casimir energy and
pressure. We show that the energy density $\mathcal{E}_{C}$ (and hence the
pressure) can be expressed in terms of the Lorentz-invariant energy density
$\mathcal{E}_{0}$ as follows \begin{align}
  \mathcal{E}_{C} (L) = \sqrt{\frac{1-\lambda u_{n} ^{2}}{1 + \lambda u ^{2}}}
\mathcal{E}_{0} (\tilde{L}) , \notag \end{align} where $\tilde{L} = L /
\sqrt{1-\lambda u_{n} ^{2}}$ is a rescaled plate-to-plate separation and
$u_{n}$ is the component of $\vec{{u}}$ along the normal to the plates. As
usual, divergences of the local Casimir energy do not contribute to the
pressure.",2005.00151v1
2020-05-16,Casimir effect of a Lorentz-violating scalar in magnetic field,"In this paper I study the Casimir effect caused by a charged and massive
scalar field that breaks Lorentz invariance in a CPT-even, aether-like manner.
I investigate the case of a scalar field that satisfies Dirichlet or mixed
(Dirichlet-Neumann) boundary conditions on a pair of very large plane parallel
plates. The case of Neumann boundary conditions is straightforward and will not
be examined in detail. I use the $\zeta$-function regularization technique to
study the effect of a constant magnetic field, orthogonal to the plates, on the
Casimir energy and pressure. I investigate the cases of a timelike Lorentz
asymmetry, a spacelike Lorentz asymmetry in the direction perpendicular to the
plates, and a spacelike asymmetry in the plane of the plates and, in all those
cases, derive simple analytic expressions for the zeta function, Casimir energy
and pressure in the limits of small plate distance, strong magnetic field and
large scalar field mass. I discover that the Casimir energy and pressure, and
their magnetic corrections, all strongly depend on the direction of the unit
vector that implements the breaking of the Lorentz symmetry.",2005.07830v2
2020-08-24,Aspects and applications of nonlocal Lorentz-violation,"We consider simple scalar theories with quadratic terms that are nonlocal and
Lorentz violating. Unlike similar Lorentz-invariant nonlocal theories that we
have considered previously, the theories studied here are both ghost-free and
unitary as formulated in Minkowski space. We explore the possibility that the
scale of nonlocality could be low in a dark sector, where the stringent
constraints on the violation of Lorentz invariance may be accommodated via the
weak coupling to the standard model. We point out that long-range forces may
originate from such a sector and be distinguishable from more conventional
beyond-the-standard model possibilities. We present a model in which a
nonlocal, Lorentz-violating dark sector communicates with the standard model
via a sector of heavy vector-like fermions, a concrete framework in which
phenomenological constraints and signals can be investigated.",2008.10525v2
2020-09-20,Poincaré crystal on the one-dimensional lattice,"In this paper, we develop the quantum theory of particles that has discrete
Poincar\'{e} symmetry on the one-dimensional Bravais lattice. We review the
recently discovered discrete Lorentz symmetry, which is the unique Lorentz
symmetry that coexists with the discrete space translational symmetry on a
Bravais lattice. The discrete Lorentz transformations and spacetime
translations form the discrete Poincar\'{e} group, which are represented by
unitary operators in a quantum theory. We find the conditions for the existence
of representation, which are expressed as the congruence relation between
quasi-momentum and quasi-energy. We then build the Lorentz-invariant many-body
theory of indistinguishable particles by expressing both the unitary operators
and Floquet Hamiltonians in terms of the field operators. Some typical
Hamiltonians include the long-range hopping which fluctuates as the distance
between sites increases. We calculate the Green's functions of the lattice
theory. The spacetime points where the Green's function is nonzero display a
lattice structure. During the propagation, the particles stay localized on a
single or a few sites to preserve the Lorentz symmetry.",2009.09441v1
2021-02-19,Classical Lagrangians for the nonminimal spin-nondegenerate Standard-Model Extension at higher orders in Lorentz violation,"We present new results for classical-particle propagation subject to Lorentz
violation. Our analysis is dedicated to spin-nondegenerate operators of
arbitrary mass dimension provided by the fermion sector of the Standard-Model
Extension. In particular, classical Lagrangians are obtained for the operators
$\hat{b}_{\mu}$ and $\hat{H}_{\mu\nu}$ as perturbative expansions in Lorentz
violation. The functional dependence of the higher-order contributions in the
background fields is found to be quite peculiar, which is probably attributed
to particle spin playing an essential role for these cases. This paper closes
one of the last gaps in understanding classical-particle propagation in the
presence of Lorentz violation. Lagrangians of the kind presented will turn out
to be valuable for describing particle propagation in curved backgrounds with
diffeomorphism invariance and/or local Lorentz symmetry explicitly violated.",2102.10164v1
2021-04-06,Correlation effects obtained from optical spectra of Fe-pnictides using an extended Drude-Lorentz model analysis,"We introduce an analysis model, an extended Drude-Lorentz model, and apply it
to Fe-pnictide systems to extract their electron-boson spectral density
functions (or correlation spectra). The extended Drude-Lorentz model consists
of an extended Drude mode for describing correlated charge carriers and Lorentz
modes for interband transitions. The extended Drude mode can be obtained by a
reverse process starting from the electron-boson spectral density function and
extending to the optical self-energy and, eventually, to the optical
conductivity. Using the extended Drude-Lorentz model, we obtained the
electron-boson spectral density functions of K-doped BaFe$_2$As$_2$ (Ba-122) at
four different doping levels. We discuss the doping-dependent properties of the
electron-boson spectral density function of K-doped Ba-122. We also can include
pseudogap effects in the model using this approach. Therefore, this approach is
very helpful for understanding and analyzing measured optical spectra of
strongly correlation electron systems, including high-temperature
superconductors (cuprates and Fe-pnictides).",2104.02353v2
2021-04-14,Aspects of Lorentz-Poincaré-symmetry violating physics in a supersymmetric scenario,"We study a Lorentz invariance violating extension for the pure photonic
sector of the standard model in a supersymmetric scenario. We identify a number
of independent background fermion condensates. An effective photonic action is
proposed which is induced by the SUSY background fermion condensates. The
physical consequences leading to direct measurable effects over the screening
and confining properties are considered. In the specific case of the
Carroll-Field-Jackiw, we pay special attention in analyzing the dispersion
relations to derive the photon and photino masses in terms of the
supersymmetric background parameters. In connection with astrophysical aspects
of Lorentz-symmetry violation, we discuss the time delay between
electromagnetic waves of different frequencies as a consequence of the
appearance of the massive photon. We also point out that, in the scenario we
propose to accommodate Lorentz-symmetry violation in presence of a
supersymmetric background, there is room for a sort of fermionic Primakoff
effect in which a photino-photon conversion may be induced by the fermionic
sector of the supersymmetric background.",2104.06875v1
2021-06-28,Shadow cast by Kerr-like black hole in the presence of plasma in Einstein-bumblebee gravity,"In the Einstein-bumblebee gravity, the Lorentz symmetry is spontaneously
broken by a vector field. In this paper, we attempt to test the Lorentz
symmetry via the observation of the shadow cast by the Kerr-like black hole
with or without plasma. A novel phenomenon of the Lorentz-violating parameter
on the shadow is observed. The result shows that when the observer gradually
moves from the poles to the equatorial plane, the shadow radius $R_{\rm s}$
firstly decreases and then increases with the Lorentz-violating parameter. Such
nonmonotonic behavior provides us an important understanding on the black hole
shadow in the Einstein-bumblebee gravity. Besides, three more distortion
observables are calculated, and found to increase with the Lorentz-violating
parameter. Moreover, when a homogeneous plasma is present, the motion of the
photon is analyzed. We further observe that the refractive index shrinks the
size, while enhances the deformation of the shadow. Finally, adopting the
observed data of the diameter of M87$^*$, we find the refractive index is more
favored in (0.914, 1).",2106.14602v1
2021-08-06,New limits on the Lorentz/CPT symmetry through fifty gravitational-wave events,"Lorentz invariance plays a fundamental role in modern physics. However, tiny
violations of the Lorentz invariance may arise in some candidate quantum
gravity theories. Prominent signatures of the gravitational Lorentz invariance
violation (gLIV) include anisotropy, dispersion, and birefringence in the
dispersion relation of gravitational waves (GWs). Using a total of 50 GW events
in the GW transient catalogs GWTC-1 and GWTC-2, we perform an analysis on the
anisotropic birefringence phenomenon. The use of multiple events allows us to
completely break the degeneracy among gLIV coefficients and globally constrain
the coefficient space. Compared to previous results at mass dimensions 5 and 6
for the Lorentz-violating operators, we tighten the global limits of 34
coefficients by factors ranging from $2$ to $7$.",2108.02974v2
2022-01-03,Strengthened Fractional Sobolev Type Inequalities in Besov Spaces,"The purpose of this article is twofold. The first is to strengthen fractional
Sobolev type inequalities in Besov spaces via the classical Lorentz space. In
doing so, we show that the Sobolev inequality in Besov spaces is equivalent to
the fractional Hardy inequality and the iso-capacitary type inequality.
Secondly, we will strengthen fractional Sobolev type inequalities in Besov
spaces via capacitary Lorentz spaces associated with Besov capacities. For this
purpose, we first study the embedding of the associated capacitary Lorentz
space to the classical Lorentz space. Then, the embedding of the Besov space to
the capacitary Lorentz space is established. Meanwhile, we show that these
embeddings are closely related to the iso-capacitary type inequalities in terms
of a new-introduced fractional $(\beta, p, q)$-perimeter. Moreover,
characterizations of more general Sobolev type inequalities in Besov spaces
have also been established.",2201.00753v2
2022-04-20,Loop correction to the scalar Casimir energy density and generation of topological mass due to a helix boundary condition in a scenario with Lorentz violation,"In this paper the effective potential approach in quantum field theory is
used in order to investigate self-interaction loop correction to the Casimir
energy density and generation of topological mass for both massless and massive
real scalar fields. It is assumed that the scalar field obeys a helix boundary
condition. In addition, it is also considered a CPT-even aether-type violation
of the Lorentz symmetry. In the absence of the Lorentz violation we obtain
analytical expressions for the loop correction to the Casimir energy density
and to the mass of the scalar field. The same expressions are also obtained
assuming the Lorentz violation in each of the spacetime directions. We also
show some graphs that exhibit how the loop correction and the Lorentz violation
affect the the Casimir energy density and the mass of the scalar field.",2204.09400v3
2022-08-24,The Structure of Geodesic Orbit Lorentz Nilmanifolds,"The geodesic orbit property is useful and interesting in Riemannian geometry.
It implies homogeneity and has important classes of Riemannian manifolds as
special cases. Those classes include weakly symmetric Riemannian manifolds and
naturally reductive Riemannian manifolds. The corresponding results for
indefinite metric manifolds are much more delicate than in Riemannian
signature, but in the last few years important corresponding structural results
were proved for geodesic orbit Lorentz manifolds. Here we carry out a major
step in the structural analysis of geodesic orbit Lorentz nilmanifolds. Those
are the geodesic orbit Lorentz manifolds $M = G/H$ such that a nilpotent
analytic subgroup of $G$ is transitive on $M$. Suppose that there is a
reductive decomposition $\mathfrak{g} = \mathfrak{h} \oplus \mathfrak{n}$
(vector space direct sum) with $\mathfrak{n}$ nilpotent. When the metric is
nondegenerate on $[\mathfrak{n},\mathfrak{n}]$ we show that $\mathfrak{n}$ is
abelian or 2-step nilpotent (this is the same result as for geodesic orbit
Riemannian nilmanifolds), and when the metric is degenerate on
$[\mathfrak{n},\mathfrak{n}]$ we show that $\mathfrak{n}$ is a Lorentz double
extension corresponding to a geodesic orbit Riemannian nilmanifold. In the
latter case we construct examples to show that the number of nilpotency steps
is unbounded.",2208.11256v1
2022-08-30,Inflationary Adler Conditions,"We derive a new soft theorem that corresponds to the spontaneous breaking of
Lorentz boosts. This is motivated by the dynamics of inflation in the
sub-horizon (flat-space) limit, where spacetime becomes flat but Lorentz boosts
are still broken. In this limit, the scattering amplitudes become sensible
observables. We relate the soft emission of a Goldstone boson to the
(non-relativistic) Lorentz boost of the hard scattering amplitudes. This is the
on-shell avatar of the spontaneous breaking of Lorentz boosts, analogous to the
Adler zero of pions in the chiral symmetry breaking. We comment on several
applications to inflation, including the demonstration that Dirac-Born-Infeld
Inflation is the unique theory that has an emergent Lorentz invariance when the
boosts are spontaneously broken.",2208.14544v2
2022-10-07,Modified Hawking temperatures of black holes in Lorentz violation theory,"In this paper, the tunneling of scalar particles near the event horizons of
Riemann space time, BTZ black hole and Schwarzschild-de Sitter black hole are
investigated by applying Hamilton-Jacobi equation with Lorentz violation theory
in curved space time. The modified Hamilton-Jacobi equation is derived from
Klein-Gordon equation of scalar particles induced by Lorentz violation theory
in curved space time. The Hawking temperatures of Riemann space time and the
BTZ black hole are modified due to the effect of Lorentz violation theory.
Moreover, the Bekenstein-Hawking entropy near the event horizon of
Schwarzschild-de Sitter black hole is also modified due to Lorentz violation
theory. It is observed that the modified values of Hawking temperatures and
change in Bekenstein-Hawking entropy depend upon the ether-like vectors
$u^\alpha$.",2210.03443v1
2022-11-21,Three- and Four-Point Functions in CPT-Even Lorentz-Violating Scalar QED,"The renormalization of quantum field theories usually assumes Lorentz and
gauge symmetries, besides the general restrictions imposed by unitarity and
causality. However, the set of renormalizable theories can be enlarged by
relaxing some of these assumptions. In this work, we consider the particular
case of a CPT-preserving but Lorentz-breaking extension of scalar QED. For this
theory, we calculate the one-loop radiative corrections to the three- and
four-point scalar-vector vertex functions, at the lowest order in the Lorentz
violation parameters; and we explicitly verify that the resulting low-energy
effective action is compatible with the usual gauge invariance requirements.
With these results, we complete the one-loop renormalization of the model at
the leading order in the Lorentz-violating parameters.",2211.11399v4
2022-12-22,Effects of Lorentz Symmetry Breaking Environment on Generalized Relativistic Quantum Oscillator Field,"In this paper, we study the generalized Klein-Gordon oscillator equation
under the effects of the violation of Lorentz Symmetry defined by a tensor
field $(K_F)_{\mu\nu\alpha\beta}$ out of the Standard Model Extension (SME). We
consider a possible scenario of the Lorentz-Violating effects with a
Cornell-type electric field and a linear magnetic field that contributes a
harmonic-type central potential in the relativistic quantum motions of scalar
oscillator fields. The bound-states solutions of the wave equation using the
parametric Nikiforov-Uvarov method by considering a Coulomb and Cornell-type
potential form functions are obtained. We see that the eigenvalue solutions get
modified by the Lorentz symmetry-breaking effects in comparison to the Landau
levels (without Lorentz-Violation effects in flat space)",2212.12426v1
2023-01-16,Are inertial vacua equivalent in Lorentz-violating theories? Does it matter?,"Several approaches to quantum gravity suggest violations of Lorentz symmetry
as low-energy signatures. This article uses a concrete Lorentz-violating
quantum field theory to study different inertial vacua. We show that they are
unitarily inequivalent and that the vacuum in one inertial frame appears, in a
different inertial frame, to be populated with particles of arbitrarily high
momenta. At first sight, this poses a critical challenge to the physical
validity of Lorentz-violating theories, since we do not witness vacuum
excitations by changing inertial frames. Nevertheless, we demonstrate that
inertial Unruh-De Witt detectors are insensitive to these effects. We also
discuss the Hadamard condition for this Lorentz-violating theory.",2301.06600v2
2023-02-17,Casimir effect in a Lorentz-violating tensor extension of a scalar field theory,"This paper investigates the Casimir Energy modifications due to the
Lorentz-violating CPT-even contribution in an extension of the scalar QED. We
have considered the complex scalar field satisfying Dirichlet boundary
conditions between two parallel plates separated by a small distance. An
appropriate tensor parametrization allowed us to study the Casimir effect in
three setups: isotropic, anisotropic parity-odd, and anisotropic parity-even.
We have shown that the Lorentz-violating contributions promote increased
Casimir energy for both the isotropic and anisotropic parity-odd
configurations. However, in the parity-even case, the Lorentz-violating terms
can promote either an increase or a decrease in the Casimir energy. We have
shown that both the increased and decreased amounts in the Casimir energy
depend on the momentum projection over the Lorentz-violating vectors.",2302.08836v1
2023-03-23,Vacuum polarization in Yang-Mills theories with Lorentz violation,"The renormalizable extension of a pure Yang-Mills theory with Lorentz
violation is characterized by the CPT-Even $(k_F)_{\mu \nu \lambda \rho}$ and
the CPT-Odd $(k_{AF})_\mu$ constant Lorentz coefficients. In this paper, the
one-loop structure of the theory up to second order in these Lorentz violating
coefficients is studied using the BFM-gauge. Results for the diverse beta
functions are derived and contrasted with those given in the literature at
first order in these parameters. Special emphasis is putted on the beta
function $\beta(g)$, which is studied in both mass-independent and
mass-dependent renormalization schemes. It is found that in a mass-independent
scheme the $(k_{AF})_\mu$ Lorentz coefficient does not contribute to the
$\beta(g)$ function, but it does in a mass-dependent scheme with contributions
that are gauge-dependent and IR divergent.",2303.12969v1
2023-03-23,Brownian Yet Non-Gaussian Diffusion of a Light Particle in Heavy Gas: Lorentz Gas Based Analysis,"Non-Gaussian diffusion was recently observed in gas mixtures with mass and
fraction contrast [F. Nakai et al, Phys. Rev. E 107, 014605 (2023)]. The mean
square displacement of a minor gas particle with a small mass is linear in
time, while the displacement distribution deviates from the Gaussian
distribution, which is called the Brownian yet non-Gaussian diffusion. In this
work, we theoretically analyze this case where the mass contrast is
sufficiently large. Major heavy particles can be interpreted as immobile
obstacles, and a minor light particle behaves like a Lorentz gas particle
within an intermediate time scale. Despite the similarity between the gas
mixture and the conventional Lorentz gas system, the Lorentz gas description
cannot fully describe the Brownian yet non-Gaussian diffusion. A successful
description can be achieved through an ensemble average of the statistical
quantities of the Lorentz gas over the initial speed.",2303.13119v2
2023-07-16,"Pseudo-Riemannian geodesic orbit nilmanifolds of signature $\boldsymbol{(n-2,2)}$","The geodesic orbit property is useful and interesting in itself, and it plays
a key role in Riemannian geometry. It implies homogeneity and has important
classes of Riemannian manifolds as special cases. Those classes include weakly
symmetric Riemannian manifolds and naturally reductive Riemannian manifolds.
The corresponding results for indefinite metric manifolds are much more
delicate than in Riemannian signature, but in the last few years important
corresponding structural results were proved for geodesic orbit Lorentz
manifolds. Here we extend Riemannian and Lorentz results to trans-Lorentz
nilmanifolds. Those are the geodesic orbit pseudo Riemannian manifolds $M =
G/H$ of signature $(n-2,2)$ such that a nilpotent analytic subgroup of $G$ is
transitive on $M$. For that we suppose that there is a reductive decomposition
$\g = \h \oplus \n \text{ (vector space direct sum) with } [\h,\n] \subset \n$
and $\n$ nilpotent. When the metric is nondegenerate on $[\n,\n]$ we show that
$\n$ is abelian or 2-step nilpotent. That is the same result as for geodesic
orbit Riemannian and Lorentz nilmanifolds. When the metric is degenerate on
$[\n,\n]$ we show that $\n$ is a double extension of a geodesic orbit
nilmanifold of either Riemannian or Lorentz signature.",2307.07937v1
2023-08-11,Experimental realization of Lorentz boosts of space-time wave packets,"It is now well-understood that a Lorentz boost of a spatially coherent
monochromatic optical beam yields a so-called space-time wave packet (STWP): a
propagation-invariant pulsed beam whose group velocity is determined by the
relative velocity between the source and observer. Moreover, the Lorentz boost
of an STWP is another STWP, whose group velocities are related by the
relativistic law for addition of velocities typically associated with massive
particles. We present an experimental procedure for testing this prediction in
both the subluminal and superluminal regimes that makes use of spatio-temporal
Fourier synthesis via a spatial light modulator. Our approach enables realizing
the change in temporal bandwidth, the invariance of the spatial bandwidth, the
concomitant change in the spatio-temporal wave-packet envelope, and the change
in group velocity that all accompany a Lorentz boost of a monochromatic optical
beam. The only consequence of the Lorentz boost not captured by this
methodology is the Doppler shift in the optical carrier. This work may provide
an avenue for further table-top demonstration of relativistic transformations
of optical fields.",2308.06387v2
2023-08-12,Static and spherically symmetric black holes in gravity with a background Kalb-Ramond field,"The Lorentz symmetry of gravity is spontaneously broken when the nonminimally
coupled Kalb-Ramond field acquires a nonzero vacuum expectation value. In this
work, we present exact solutions for static and spherically symmetric black
holes in the framework of this Lorentz-violating gravity theory. In order to
explore the physical implications of Lorentz violation, we analyze the
thermodynamic properties of the obtained solutions and evaluate the impact of
Lorentz violation on some classical gravitational experiments within the Solar
System. Furthermore, the Lorentz-violating parameter is constrained by using
the measured results of these experiments.",2308.06613v2
2023-08-15,Sensitivity to CP Discovery in the Presence of Lorentz Invariance Violating Potential at T2HK/T2HKK,"Investigation of conservation/violation of CP symmetry in the leptonic sector
is very essential in understanding the evolution of the universe. Lorentz
invariance and CPT are fundamental symmetries of nature. The violation of
Lorentz invariance can also lead to CPT violations. The standard three flavour
neutrino oscillation framework presents a scenario to observe the signature of
Lorentz invariance and CP violations. This work focuses on the effect of
Lorentz invariance violating (LIV) parameters on the sensitivity to CP
violation. We investigate the sensitivity in two proposed configurations of the
upcoming T2HK experiment: (i) one detector each placed at 295 km and 1100 km,
and (ii) two identical detectors at 295 km. This study probes the effect of CPT
violating parameters $a_{e\mu},a_{e\tau},a_{\mu\tau}$.",2308.07566v2
2023-09-04,Search for Lorentz-violation through sidereal effect at NOνA Experiment,"Long-baseline neutrino oscillation experiments offer a unique laboratory to
test the fundamental Lorentz symmetry, which is heart of both the standard
model of particle and general relativity theory. Deviations from the standard
neutrino oscillation or the sidereal modulation in neutrino events will
smoking-gun experimental signature of Lorentz and CPT violation. In this study,
we investigate the impact of the sidereal effect on standard neutrino
oscillation measurements within the context of the NO{\nu}A experiment.
  Additionally, we assess the sensitivity of the NO{\nu}A experiment to detect
Lorentz-violating interactions, taking into account the sidereal effect.
Furthermore, we highlight potential of the NO{\nu}A experiment to set the new
constraints on anisotropic Lorentz-violating parameters.",2309.01756v2
2023-10-09,Constraint on Lorentz invariance violation from Vela pulsar,"The High Energy Stereoscopic System (H.E.S.S) Collaboration reported the
discovery of a novel radiation component from the Vela pulsar by their
Cherenkov telescopes. It is of great importance that gamma rays with energies
of at least 20~TeV are recorded unexpectedly. The H.E.S.S Collaboration argued
that such results may challenge the state-of-the-art models for the high-energy
emission of pulsars. We point out in this work that these results also provide
a unique opportunity to constrain certain Lorentz invariance violation
parameters, leading to the realization of studying Lorentz invariance violation
by using gamma-ray pulsars. The Lorentz invariance violation scale is
constrained at the level of $E_{\mathrm{LV,}1}> 1.66\times 10^{17} \rm GeV$ for
the linear scenario, and $E_{\mathrm{LV,}2}>3.53\times 10^{10} \rm GeV$ for the
quadratic scenario. We anticipate that digging into the detailed features of
the data of the Vela pulsar and analyzing potentially more very-high-energy
photon data from pulsars in the future would improve the constraints on Lorentz
invariance violation.",2310.06052v1
2023-11-26,Poincaré--Sobolev Inequalities Based on Choquet--Lorentz Integrals with Respect to Hausdorff Contents on Bounded John Domains,"Let $\Omega$ be a bounded John domain in $\mathbb R^n$ with $n\ge 2$, and let
$\mathcal{H}_{\infty }^{\delta}$ denote the Hausdorff content of dimension
$\delta\in (0,n]$. In this article, the authors prove the Poincar\'e and the
Poincar\'e--Sobolev inequalities on Choquet--Lorentz integrals with respect to
$\mathcal{H}_{\infty }^{\delta}$ for all continuously differentiable functions
on $\Omega$. These results not only extend the recent Poincar\'e and
Poincar\'e--Sobolev inequalities, obtained by Harjulehto and Hurri-Syrj\""{a}nen
in [J. Funct. Anal. 284 (2023), Paper No. 109862], to the Choquet--Lorentz
integrals, but also provide some endpoint estimates (weak type) of their
results in the critical case. One of the main novelties exists in that, to
achieve the goals, the authors develop some new tools associated with
Choquet--Lorentz integrals on $\mathcal{H}_{\infty }^{\delta}$, such as the
fractional Hardy--Littlewood maximal inequality and the inner interpolation
theorem of sublinear operators. Moreover, even for classical Lorentz integrals,
these Poincar\'e and Poincar\'e--Sobolev inequalities are also new.",2311.15224v2
2009-08-21,Surface Alfven Wave Damping in a 3D Simulation of the Solar Wind,"Here we investigate the contribution of surface Alfven wave damping to the
heating of the solar wind in minima conditions. These waves are present in
regions of strong inhomogeneities in density or magnetic field (e. g., the
border between open and closed magnetic field lines). Using a 3-dimensional
Magnetohydrodynamics (MHD) model, we calculate the surface Alfven wave damping
contribution between 1-4 solar radii, the region of interest for both
acceleration and coronal heating. We consider waves with frequencies lower than
those that are damped in the chromosphere and on the order of those dominating
the heliosphere. In the region between open and closed field lines, within a
few solar radii of the surface, no other major source of damping has been
suggested for the low frequency waves we consider here. This work is the first
to study surface Alfven waves in a 3D environment without assuming a priori a
geometry of field lines or magnetic and density profiles. We determine that
waves with frequencies >2.8x10^-4 Hz are damped between 1-4 solar radii. In
quiet sun regions, surface Alfven waves are damped at further distances
compared to active regions, thus carrying additional wave energy into the
corona. We compare the surface Alfven wave contribution to the heating by a
variable polytropic index and find that it an order of magnitude larger than
needed for quiet sun regions. For active regions the contribution to the
heating is twenty percent. As it has been argued that a variable gamma acts as
turbulence, our results indicate that surface Alfven wave damping is comparable
to turbulence in the lower corona. This damping mechanism should be included
self consistently as an energy driver for the wind in global MHD models.",0908.3146v1
2014-03-19,The effects of time-dependent dissipation on the basins of attraction for the pendulum with oscillating support,"We consider a pendulum with vertically oscillating support and time-dependent
damping coefficient which varies until reaching a finite final value. The sizes
of the corresponding basins of attraction are found to depend strongly on the
full evolution of the dissipation. In order to predict the behaviour of the
system, it is essential to understand how the sizes of the basins of attraction
for constant dissipation depend on the damping coefficient. For values of the
parameters in the perturbation regime, we characterise analytically the
conditions under which the attractors exist and study numerically how the sizes
of their basins of attraction depend on the damping coefficient. Away from the
perturbation regime, a numerical study of the attractors and the corresponding
basins of attraction for different constant values of the damping coefficient
produces a much more involved scenario: changing the magnitude of the
dissipation causes some attractors to disappear either leaving no trace or
producing new attractors by bifurcation, such as period doubling and
saddle-node bifurcation. For an initially non-constant damping coefficient,
both increasing and decreasing to some finite final value, we numerically
observe that, when the damping coefficient varies slowly from a finite initial
value to a different final value, without changing the set of attractors, the
slower the variation the closer the sizes of the basins of attraction are to
those they have for constant damping coefficient fixed at the initial value. If
during the variation of the damping coefficient attractors appear or disappear,
remarkable additional phenomena may occur. For instance, a fixed point
asymptotically may attract the entire phase space, up to a zero measure set,
even though no attractor with such a property exists for any value of the
damping coefficient between the extreme values.",1403.4996v1
2019-09-19,"Nonlinear energy loss in the oscillations of coated and uncoated bubbles: Role of thermal, radiation damping and encapsulating shell at various excitation pressures","A simple generalized model (GM) for coated bubbles accounting for the effect
of compressibility of the liquid is presented. The GM was then coupled with
nonlinear ODEs that account for the thermal effects. Starting with mass and
momentum conservation equations for a bubbly liquid and using the GM, nonlinear
pressure dependent terms were derived for energy dissipation due to thermal
damping (Td), radiation damping (Rd) and dissipation due to the viscosity of
liquid (Ld) and coating (Cd). The dissipated energies were solved for uncoated
and coated 2- 20 $\mu m$ bubbles over a frequency range of $0.25f_r-2.5f_r$
($f_r$ is the bubble resonance) and for various acoustic pressures
(1kPa-300kPa). Thermal effects were examined for air and C3F8 gas cores in each
case. For uncoated bubbles with an air gas core and a diameter larger than 4
$\mu m$, thermal damping is the strongest damping factor. When pressure
increases, the contributions of Rd grow faster and become the dominant damping
mechanism for pressure dependent resonance frequencies (e.g. fundamental and
super harmonic resonances). For coated bubbles, Cd is the strongest damping
mechanism. As pressure increases Rd contributes more to damping compared to Ld
and Td. In case of air bubbles, as pressure increases, the linear thermal model
largely deviates from the nonlinear model and accurate modeling requires
inclusion of the full thermal model. However, for coated C3F8 bubbles of
diameter 1-8 $\mu m$, typically used in medical ultrasound, thermal effects
maybe neglected even at higher pressures. We show that the scattering to
damping ratio (STDR), a measure of the effectiveness of the bubble as contrast
agent, is pressure dependent and can be maximized for specific frequency ranges
and pressures.",1909.08793v1
2017-11-21,Determination of spin Hall effect and spin diffusion length of Pt from self-consistent fitting of damping enhancement and inverse spin-orbit torque measurements,"Understanding the evolution of spin-orbit torque (SOT) with increasing
heavy-metal thickness in ferromagnet/normal metal (FM/NM) bilayers is critical
for the development of magnetic memory based on SOT. However, several
experiments have revealed an apparent discrepancy between damping enhancement
and damping-like SOT regarding their dependence on NM thickness. Here, using
linewidth and phase-resolved amplitude analysis of vector network analyzer
ferromagnetic resonance (VNA-FMR) measurements, we simultaneously extract
damping enhancement and both field-like and damping-like inverse SOT in
Ni$_{80}$Fe$_{20}$/Pt bilayers as a function of Pt thickness. By enforcing an
interpretation of the data which satisfies Onsager reciprocity, we find that
both the damping enhancement and damping-like inverse SOT can be described by a
single spin diffusion length ($\approx$ 4 nm), and that we can separate the
spin pumping and spin memory loss (SML) contributions to the total damping.
This analysis indicates that less than 40% of the angular momentum pumped by
FMR through the Ni$_{80}$Fe$_{20}$/Pt interface is transported as spin current
into the Pt. On account of the SML and corresponding reduction in total spin
current available for spin-charge transduction in the Pt, we determine the Pt
spin Hall conductivity ($\sigma_\mathrm{SH} = (2.36 \pm 0.04)\times10^6
\Omega^{-1} \mathrm{m}^{-1}$) and bulk spin Hall angle
($\theta_\mathrm{SH}=0.387 \pm0.008$) to be larger than commonly-cited values.
These results suggest that Pt can be an extremely useful source of SOT if the
FM/NM interface can be engineered to minimize SML. Lastly, we find that
self-consistent fitting of the damping and SOT data is best achieved by a model
with Elliott-Yafet spin relaxation and extrinsic inverse spin Hall effect, such
that both the spin diffusion length and spin Hall conductivity are proportional
to the Pt charge conductivity.",1711.07654v2
2020-11-20,The effect of magnetic field on the damping of slow waves in the solar corona,"Slow magnetoacoustic waves are routinely observed in astrophysical plasma
systems such as the solar corona. As a slow wave propagates through a plasma,
it modifies the equilibrium quantities of density, temperature, and magnetic
field. In the corona and other plasma systems, the thermal equilibrium is
comprised of a balance between continuous heating and cooling processes, the
magnitudes of which vary with density, temperature and magnetic field. Thus the
wave may induce a misbalance between these competing processes. Its back
reaction on the wave has been shown to lead to dispersion, and amplification or
damping, of the wave. In this work the importance of the effect of magnetic
field in the rapid damping of slow waves in the solar corona by heating/cooling
misbalance is evaluated and compared to the effects of thermal conduction. The
two timescales characterising the effect of misbalance are derived and
calculated for plasma systems with a range of typical coronal conditions. The
predicted damping times of slow waves from thermal misbalance in the solar
corona are found to be of the order of 10-100 minutes, coinciding with the wave
periods and damping times observed. Moreover the slow wave damping by thermal
misbalance is found to be comparable to the damping by field-aligned thermal
conduction. We show that in the infinite field limit, the wave dynamics is
insensitive to the dependence of the heating function on the magnetic field,
and this approximation is found to be valid in the corona so long as the
magnetic field strength is greater than 10G for quiescent loops and plumes and
100G for hot and dense loops. In summary thermal misbalance may damp slow
magnetoacoustic waves rapidly in much of the corona, and its inclusion in our
understanding of slow mode damping may resolve discrepancies between
observations and theory relying on compressive viscosity and thermal conduction
alone.",2011.10437v1
2023-06-22,"Gilbert damping in metallic ferromagnets from Schwinger-Keldysh field theory: Intrinsically nonlocal and nonuniform, and made anisotropic by spin-orbit coupling","Understanding the origin of damping mechanisms in magnetization dynamics of
metallic ferromagnets is a fundamental problem for nonequilibrium many-body
physics of systems where quantum conduction electrons interact with localized
spins assumed to be governed by the classical Landau-Lifshitz-Gilbert (LLG)
equation. It is also of critical importance for applications, as damping
affects energy consumption and speed of spintronic and magnonic devices. Since
the 1970s, a variety of linear-response and scattering theory approaches have
been developed to produce widely used formulas for computation of
spatially-independent Gilbert scalar parameter as the magnitude of the Gilbert
damping term in the LLG equation. The largely unexploited for this purpose
Schwinger-Keldysh field theory (SKFT) offers additional possibilities, such as
to rigorously derive an extended LLG equation by integrating quantum electrons
out. Here we derive such equation whose Gilbert damping for metallic
ferromagnets is nonlocal, i.e., dependent on all localized spins at a given
time, and nonuniform, even if all localized spins are collinear and spin-orbit
coupling (SOC) is absent. This is in sharp contrast to standard lore, where
nonlocal damping is considered to emerge only if localized spins are
noncollinear; for such situations, direct comparison on the example of magnetic
domain wall shows that SKFT-derived nonlocal damping is an order of magnitude
larger than the previously considered one. Switching on SOC makes such nonlocal
damping anisotropic, in contrast to standard lore where SOC is usually
necessary to obtain nonzero Gilbert damping scalar parameter. Our analytical
formulas, with their nonlocality being more prominent in low spatial
dimensions, are fully corroborated by numerically exact quantum-classical
simulations.",2306.13013v4
1997-11-25,Abundances of Heavy Elements and CO Molecules in High Redshift Damped Lyman-alpha Galaxies,"Damped Lyman-alpha systems seen in spectra of background quasars are
generally thought to represent high redshift counterparts of present-day
galaxies. We summarize observations of heavy element abundances in damped
Lyman-alpha systems. The results of a systematic search for CO and C II*
absorption in 17 damped Lyman-alpha systems are also presented using
observations obtained with the 10m Keck telescopes. The latter provides a
useful constraint on the expected strength of [C II] 158 micron emission from
damped Lyman-alpha galaxies. It is hoped that these results will be useful for
planning future radio to millimeter wave observations of high redshift galaxies
using next generation instruments which are now being built.",9711298v1
1997-12-05,Magnetohydrodynamics in the Early Universe and the Damping of Non-linear Alfven Waves,"The evolution and viscous damping of cosmic magnetic fields in the early
universe, is analysed. Using the fact that the fluid, electromagnetic, and
shear viscous energy-momentum tensors are all conformally invariant, the
evolution is transformed from the expanding universe setting into that in flat
spacetime. Particular attention is paid to the evolution of nonlinear Alfven
modes. For a small enough magnetic field, which satisfies our observational
constraints, these wave modes either oscillate negligibly or, when they do
oscillate, become overdamped. Hence they do not suffer Silk damping on galactic
and subgalactic scales. The smallest scale which survives damping depends on
the field strength and is of order a dimensionless Alfven velocity times the
usual baryon-photon Silk damping scale. After recombination, nonlinear effects
can convert the Alfven mode into compressional, gravitationally unstable waves
and seed cosmic structures if the cosmic magnetic field is sufficiently strong.",9712083v1
2001-08-09,Are Simulations of CDM Consistent with Galactic-Scale Observations at High Redshift?,"We compare new observations on the kinematic characteristics of the damped
Lya systems against results from numerical SPH simulations to test the
predictions of hierarchical galaxy formation. This exercise is particularly
motivated by recent numerical results on the cross-section of damped Lya
systems. Our analysis focuses on the velocity widths of ~50 low-ion absorption
profiles from our sample of z>1.5 damped Lya systems. The results indicate that
current numerical simulations fail to match the damped Lya observations at high
confidence levels (>99.9%). Although we do not believe that our results present
an insurmountable challenge to the paradigm of hierarchical cosmology, the
damped Lya observations suggest that current numerical SPH simulations overlook
an integral aspect of galaxy formation.",0108154v1
2003-03-19,Distinct Abundance Patterns in Multiple Damped Ly-alpha Galaxies: Evidence for Truncated Star Formation?,"(abridged) Following our previous work on metal abundances of a double damped
Ly-alpha system with a line-of-sight separation ~2000 km/s (Ellison & Lopez
2001), we present VLT UVES abundances of 3 new systems spanning a total of
\~6000 km/s at z~2.5 toward the southern QSO CTQ247. These abundances are
supplemented with echelle observations of another `double' damped Ly-alpha
system in the literature. We propose a definition in terms of velocity shift of
the sub-class 'multiple damped Ly-alpha system', which is motivated by its
possible connection with large-scale structure. We find that the abundance
ratio alpha/Fe is systematically low in multiple systems compared with single
systems, and with a small scatter. The same behavior is found in 2 more single
DLA systems taken from the literature that show evidence of belonging to a
galaxy group. After a careful investigation of possible sources of systematic
errors, we conclude that the low alpha/Fe ratios in multiple DLAs have a
nucleosynthetic origin. We suggest that they could be explained by reduced star
formation in multiple damped Ly-alpha systems, possibly due to environmental
effects.",0303441v1
2003-05-16,New Damped Lya Metallicities from ESI Spectroscopy of Five Palomar Sky Survey Quasars,"This paper presents chemical abundance measurements for 12 new z>3 damped Lya
systems discovered toward five quasars from the Palomar Sky Survey. We
determine HI column densities from profile fits to the observed damped Lya
profiles and measure ionic column densities and limits for all observed
metal-line transitions. This dataset, acquired with the Echellette Spectrograph
and Imager on the KeckII telescope, adds to the rapidly growing database of
damped Lya abundances. It will impact studies of chemical evolution in the
early universe and help identify candidates for detailed follow-up observations
with echelle spectrographs. We report the discovery of the first quasar
sightline with four cosmologically distinct damped Lya systems.",0305313v1
2006-07-06,Ekman layer damping of r-modes revisited,"We investigate the damping of neutron star r-modes due to the presence of a
viscous boundary (Ekman) layer at the interface between the crust and the core.
Our study is motivated by the possibility that the gravitational-wave driven
instability of the inertial r-modes may become active in rapidly spinning
neutron stars, eg. in low-mass X-ray binaries, and the fact that a viscous
Ekman layer at the core-crust interface provides an efficient damping mechanism
for these oscillations. We review various approaches to the problem and carry
out an analytic calculation of the effects due to the Ekman layer for a rigid
crust. Our analytic estimates support previous numerical results, and provide
further insight into the intricacies of the problem. We add to previous work by
discussing the effect that compressibility and composition stratification have
on the boundary layer damping. We show that, while stratification is
unimportant for the r-mode problem, composition suppresses the damping rate by
about a factor of two (depending on the detailed equation of state).",0607105v2
1997-11-05,Hydrodynamic damping in trapped Bose gases,"Griffin, Wu and Stringari have derived the hydrodynamic equations of a
trapped dilute Bose gas above the Bose-Einstein transition temperature. We give
the extension which includes hydrodynamic damping, following the classic work
of Uehling and Uhlenbeck based on the Chapman-Enskog procedure. Our final
result is a closed equation for the velocity fluctuations $\delta v$ which
includes the hydrodynamic damping due to the shear viscosity $\eta$ and the
thermal conductivity $\kappa$. Following Kavoulakis, Pethick and Smith, we
introduce a spatial cutoff in our linearized equations when the density is so
low that the hydrodynamic description breaks down. Explicit expressions are
given for $\eta$ and $\kappa$, which are position-dependent through dependence
on the local fugacity when one includes the effect of quantum degeneracy of the
trapped gas. We also discuss a trapped Bose-condensed gas, generalizing the
work of Zaremba, Griffin and Nikuni to include hydrodynamic damping due to the
(non-condensate) normal fluid.",9711036v4
1998-05-01,Finite Temperature Perturbation Theory for a Spatially Inhomogeneous Bose-condensed Gas,"We develop a finite temperature perturbation theory (beyond the mean field)
for a Bose-condensed gas and calculate temperature-dependent damping rates and
energy shifts for Bogolyubov excitations of any energy. The theory is
generalized for the case of excitations in a spatially inhomogeneous (trapped)
Bose-condensed gas, where we emphasize the principal importance of
inhomogeneouty of the condensate density profile and develop the method of
calculating the self-energy functions. The use of the theory is demonstrated by
calculating the damping rates and energy shifts of low-energy quasiclassical
excitations, i.e. the quasiclassical excitations with energies much smaller
than the mean field interaction between particles. In this case the boundary
region of the condensate plays a crucial role, and the result for the damping
rates and energy shifts is completely different from that in spatially
homogeneous gases. We also analyze the frequency shifts and damping of sound
waves in cylindrical Bose condensates and discuss the role of damping in the
recent MIT experiment on the sound propagation.",9805015v2
2002-07-30,Microscopic relaxation mechanisms and linear magnetization dynamics,"Linear magnetization dynamics in the presense of a thermal bath is analyzed
for two general classes of microscopic damping mechanisms. The resulting
stochastic differential equations are always in the form of a damped harmonic
oscillator driven by a thermal field. The damping term contains both the
interaction mechanisms and the symmetry of the magnetic system. Back
transformation from the oscillator coordinates to the magnetization variables
results in a macroscopic tensor form of damping that reflects the system
anisotropy. Scalar Landau-Lifshitz-Gilbert damping term is valid only for
systems with axial symmetry. Analysis of FMR linewith measurements versus
frequency, temperature, and film thickness in NiFe films shows good agreement
with a combination of slow-relaxing impurity and magnon-electron confluence
processes.",0207721v1
2003-10-18,Experiment and Dynamic Simulations of Radiation Damping of Laser-polarized liquid 129Xe at low magnetic field in a flow system,"Radiation damping is generally observed when the sample with high spin
concentration and high gyro-magnetic ratio is placed in a high magnetic field.
However, we firstly observed liquid state 129Xe radiation damping using
laser-enhanced nuclear polarization at low magnetic field in a flow system in
which the polarization enhancement factor for the liquid state 129Xe was
estimated to be 5000, and furthermore theoretically simulated the envelopes of
the 129Xe FID and spectral lineshape in the presence of both relaxation and
radiation damping with different pulse flip angles and ratios of T2*/Trd. The
radiation damping time constant Trd of 5 ms was derived based on the
simulations. The reasons of depolarization and the further possible
improvements were also discussed.",0310435v1
2004-03-25,XMCD characterization of rare-earth dopants in Ni$_{81}$Fe$_{19}$(50nm): microscopic basis of engineered damping,"We present direct evidence for the contribution of local orbital moments to
the damping of magnetization precession in magnetic thin films. Using x-ray
magnetic circular dichroism (XMCD) characterization of rare-earth (RE)
M$_{4,5}$ edges in Ni$_{81}$Fe$_{19}$ doped with $<$ 2% Gd and Tb, we show that
the enhancement of GHz precessional relaxation is accompanied by a significant
orbital moment fraction on the RE site. Tb impurities, which enhance the
Landau-Lifshitz(-Gilbert) LL(-G) damping $\lambda(\alpha)$, show a spin to
orbital number ratio of 1.5$\pm$0.3; Gd impurities, which have no effect on
damping, show a spin to orbital number ratio of zero within experimental error.
The results indicate that the dopant-based control of magnetization damping in
RE-doped ferromagnets is an atomistic effect, arising from spin-lattice
coupling, and thus scalable to nanometer dimensions.",0403627v1
2005-02-08,Landau Damping of Spin Waves in Trapped Boltzmann Gases,"A semiclassical method is used to study Landau damping of transverse
pseudo-spin waves in harmonically trapped ultracold gases in the collisionless
Boltzmann limit. In this approach, the time evolution of a spin is calculated
numerically as it travels in a classical orbit through a spatially dependent
mean field. This method reproduces the Landau damping results for spin-waves in
unbounded systems obtained with a dielectric formalism. In trapped systems, the
simulations indicate that Landau damping occurs for a given spin-wave mode
because of resonant phase space trajectories in which spins are ""kicked out"" of
the mode (in spin space). A perturbative analysis of the resonant and nearly
resonant trajectories gives the Landau damping rate, which is calculated for
the dipole and quadrupole modes as a function of the interaction strength. The
results are compared to a numerical solution of the kinetic equation by Nikuni
et al.",0502189v1
2005-06-01,Landau damping of Bogoliubov excitations in optical lattices at finite temperature,"We study the damping of Bogoliubov excitations in an optical lattice at
finite temperatures. For simplicity, we consider a Bose-Hubbard tight-binding
model and limit our analysis to the lowest excitation band. We use the Popov
approximation to calculate the temperature dependence of the number of
condensate atoms $n^{\rm c 0}(T)$ in each lattice well. We calculate the Landau
damping of a Bogoliubov excitation in an optical lattice due to coupling to a
thermal cloud of excitations. While most of the paper concentrates on 1D
optical lattices, we also briefly present results for 2D and 3D lattices. For
energy conservation to be satisfied, we find that the excitations in the
collision process must exhibit anomalous dispersion ({\it i.e.} the excitation
energy must bend upward at low momentum), as also exhibited by phonons in
superfluid $^4\rm{He}$. This leads to the sudden disappearance of all damping
processes in $D$-dimensional simple cubic optical lattice when $U n^{\rm c
0}\ge 6DJ$, where $U$ is the on-site interaction, and $J$ is the hopping matrix
element. Beliaev damping in a 1D optical lattice is briefly discussed.",0506016v1
2006-06-15,Landau damping: instability mechanism of superfluid Bose gases moving in optical lattices,"We investigate Landau damping of Bogoliubov excitations in a dilute Bose gas
moving in an optical lattice at finite temperatures. Using a 1D tight-binding
model, we explicitly obtain the Landau damping rate, the sign of which
determines the stability of the condensate. We find that the sign changes at a
certain condensate velocity, which is exactly the same as the critical velocity
determined by the Landau criterion of superfluidity. This coincidence of the
critical velocities reveals the microscopic mechanism of the Landau
instability. This instability mechanism is also consistent with the recent
experiment suggesting that a thermal cloud plays a crucial role in breakdown of
superfluids, since the thermal cloud is also vital in the Landau damping
process. We also examine the possibility of simultaneous disappearance of all
damping processes.",0606398v2
2006-10-10,Spin-transfer in an open ferromagnetic layer: from negative damping to effective temperature,"Spin-transfer is a typical spintronics effect that allows a ferromagnetic
layer to be switched by spin-injection. Most of the experimental results about
spin transfer are described on the basis of the Landau-Lifshitz-Gilbert
equation of the magnetization, in which additional current-dependent damping
factors are added, and can be positive or negative. The origin of the damping
can be investigated further by performing stochastic experiments, like one shot
relaxation experiments under spin-injection in the activation regime of the
magnetization. In this regime, the N\'eel-Brown activation law is observed
which leads to the introduction of a current-dependent effective temperature.
In order to justify the introduction of these counterintuitive parameters
(effective temperature and negative damping), a detailed thermokinetic analysis
of the different sub-systems involved is performed. We propose a thermokinetic
description of the different forms of energy exchanged between the electric and
the ferromagnetic sub-systems at a Normal/Ferromagnetic junction. The
corresponding Fokker Planck equations, including relaxations, are derived. The
damping coefficients are studied in terms of Onsager-Casimir transport
coefficients, with the help of the reciprocity relations. The effective
temperature is deduced in the activation regime.",0610264v1
1996-11-25,Damping rates of hard momentum particles in a cold ultrarelativistic plasma,"We compute the damping rates of one-particle excitations in a cold
ultrarelativistic plasma to leading order in the coupling constant e for three
types of interaction: Yukawa coupling to a massless scalar boson, QED and QCD.
Damping rates of charged particles in QED and QCD are of order e^3 mu, while
damping rates of other particles are of order e^4 mu or e^4 mu log(1/e). We
find that the damping rate of an electron or of a quark is constant far from
the Fermi surface, and decreases linearly with the excitation energy close to
the Fermi surface. This unusual behavior is attributed to the long-range
magnetic interactions.",9611415v2
1999-09-24,Gauge Invariance of Nonlinear Landau Damping Rate of Bose Excitations in Quark-Gluon Plasma,"On the basis of the approximate dynamical equations describing the behavior
of quark-gluon plasma (QGP) in the semiclassical limit and Yang-Mills equation,
the kinetic equation for longitudinal waves (plasmons) is obtained. With the
Ward identities the gauge invariance of obtained nonlinear Landau damping rate
is proved. The physical mechanisms defining nonlinear scattering of a plasmon
by QGP particles are analyzed. The problem on a connection of nonlinear Landau
damping rate of longitudinal oscillations with damping rate, obtained in the
framework of hard thermal loops approximation, is considered. It is shown that
the gauge-dependent part of nonlinear Landau damping rate for the plasmons with
zero momentum vanishes on mass-shell.",9909505v1
2005-07-16,Sharp estimates for the number of degrees of freedom for the damped-driven 2D Navier--Stokes equations,"We derive upper bounds for the number of asymptotic degrees (determining
modes and nodes) of freedom for the two-dimensional Navier--Stokes system and
Navier-Stokes system with damping. In the first case we obtain the previously
known estimates in an explicit form, which are larger than the fractal
dimension of the global attractor. However, for the Navier--Stokes system with
damping our estimates for the number of the determining modes and nodes are
comparable to the sharp estimates for the fractal dimension of the global
attractor. Our investigation of the damped-driven 2D Navier--Stokes system is
inspired by the Stommel--Charney barotropic model of ocean circulation where
the damping represents the Rayleigh friction. We remark that our results
equally apply to the Stommel--Charney model.",0507327v1
2006-12-04,A singular perturbation approach for choosing PageRank damping factor,"The choice of the PageRank damping factor is not evident. The Google's choice
for the value c=0.85 was a compromise between the true reflection of the Web
structure and numerical efficiency. However, the Markov random walk on the
original Web Graph does not reflect the importance of the pages because it
absorbs in dead ends. Thus, the damping factor is needed not only for speeding
up the computations but also for establishing a fair ranking of pages. In this
paper, we propose new criteria for choosing the damping factor, based on the
ergodic structure of the Web Graph and probability flows. Specifically, we
require that the core component receives a fair share of the PageRank mass.
Using singular perturbation approach we conclude that the value c=0.85 is too
high and suggest that the damping factor should be chosen around 1/2. As a
by-product, we describe the ergodic structure of the OUT component of the Web
Graph in detail. Our analytical results are confirmed by experiments on two
large samples of the Web Graph.",0612079v1
1998-10-26,Microscopic Structure of Rotational Damping,"The damping of collective rotational motion is studied microscopically,
making use of shell model calculations based on the cranked Nilsson deformed
mean-field and on residual two-body interactions, and focusing on the shape of
the gamma-gamma correlation spectra and on its systematic behavior. It is shown
that the spectral shape is directly related to the damping width of collective
rotation, \Gammarot, and to the spreading width of many-particle many-hole
configurations, \Gammamu. The rotational damping width is affected by the shell
structure, and is very sensitive to the position of the Fermi surface, besides
mass number, spin and deformation. This produces a rich variety of features in
the rotational damping phenomena.",9810066v1
2004-07-25,Rotational damping in a multi-$j$ shell particles-rotor model,"The damping of collective rotational motion is investigated by means of
particles-rotor model in which the angular momentum coupling is treated exactly
and the valence nucleons are in a multi-$j$ shell mean-field. It is found that
the onset energy of rotational damping is around 1.1 MeV above yrast line, and
the number of states which form rotational band structure is thus limited. The
number of calculated rotational bands around 30 at a given angular momentum
agrees qualitatively with experimental data. The onset of rotational damping
takes place gradually as a function of excitation energy. It is shown that the
pairing correlation between valence nucleons has a significant effect on the
appearance of rotational damping.",0407089v3
2002-06-28,Manifold Damping Of Wakefields In High Phase Advance Linacs For The NLC,"Earlier RDDS (Rounded Damped Detuned Structures) [1,2], designed, fabricated
and tested at SLAC, in collaboration with KEK, have been shown to damp
wakefields successfully. However, electrical breakdown has been found to occur
in these structures and this makes them inoperable at the desired gradient.
Recent results [3] indicate that lowering the group velocity of the
accelerating mode reduces electrical breakdown events. In order to preserve the
filling time of each structure a high synchronous phase advance (150 degrees as
opposed to 120 used in previous NLC designs) has been chosen. Here, damping of
the wakefield is analyzed. Manifold damping and interleaving of structure cell
frequencies is discussed. These wakefields impose alignment tolerances on the
cells and on the structure as a whole. Tolerance calculations are performed and
these are compared with analytic estimations.",0206090v1
2006-06-30,Nonlinear Damping of the LC Circuit using Anti-parallel Diodes,"We investigate a simple variation of the series RLC circuit in which
anti-parallel diodes replace the resistor. This results in a damped harmonic
oscillator with a nonlinear damping term that is maximal at zero current and
decreases with an inverse current relation for currents far from zero. A set of
nonlinear differential equations for the oscillator circuit is derived and
integrated numerically for comparison with circuit measurements. The agreement
is very good for both the transient and steady-state responses. Unlike the
standard RLC circuit, the behavior of this circuit is amplitude dependent. In
particular for the transient response the oscillator makes a transition from
under-damped to over-damped behavior, and for the driven oscillator the
resonance response becomes sharper and stronger as drive source amplitude
increases. The equipment is inexpensive and common to upper level physics labs.",0606261v1
1995-11-11,A New Look at the Landau's Theory of Spreading and Damping of Waves in Collisionless Plasmas,"The theory of plasma waves and Landau damping in Maxwellian plasmas, Landau's
``rule of pass around poles'' include doubtful statements, particularly related
to an artificial ``constructing'' of the dispersion equation, what should allow
the possibility of its solution otherwise not existing at all, and the
possibility of analytical continuations of corresponding very specific ruptured
functions in the one-dimensional Laplace transformation, used by Landau, what
is the base of his theory.
  We represent, as an accessible variant, a more general alternative theory
based on a two-dimensional Laplace transformation, leading to an asymptotical
in time and space solution as a complicated superposition of coupled damping
and {\em non-damping \/} plane waves and oscillations with different dispersion
laws for every constituent mode. This theory naturally and very simply explains
paradoxes of the phenomenon of plasma echo. We propose for discussion a new
ideology of plasma waves (both electron and ion-acoustic waves) qualitatively
different from the traditional theory of Landau damping for non-collisional as
well as for low-collisional plasmas.",9511001v1
2001-07-27,Quantum limits of cold damping with optomechanical coupling,"Thermal noise of a mirror can be reduced by cold damping. The displacement is
measured with a high-finesse cavity and controlled with the radiation pressure
of a modulated light beam. We establish the general quantum limits of noise in
cold damping mechanisms and we show that the optomechanical system allows to
reach these limits. Displacement noise can be arbitrarily reduced in a narrow
frequency band. In a wide-band analysis we show that thermal fluctuations are
reduced as with classical damping whereas quantum zero-point fluctuations are
left unchanged. The only limit of cold damping is then due to zero-point energy
of the mirror",0107138v2
2005-05-20,A symmetric treatment of damped harmonic oscillator in extended phase space,"Extended phase space (EPS) formulation of quantum statistical mechanics
treats the ordinary phase space coordinates on the same footing and thereby
permits the definite the canonical momenta conjugate to these coordinates . The
extended lagrangian and extended hamiltonian are defined in EPS by the same
procedure as one does for ordinary lagrangian and hamiltonian. The combination
of ordinary phase space and their conjugate momenta exhibits the evolution of
particles and their mirror images together. The resultant evolution equation in
EPS for a damped harmonic oscillator, is such that the energy dissipated by the
actual oscillator is absorbed in the same rate by the image oscillator leaving
the whole system as a conservative system. We use the EPS formalism to obtain
the dual hamiltonian of a damped harmonic oscillator, first proposed by
Batemann, by a simple extended canonical transformations in the extended phase
space. The extended canonical transformations are capable of converting the
damped system of actual and image oscillators to an undamped one, and transform
the evolution equation into a simple form. The resultant equation is solved and
the eigenvalues and eigenfunctions for damped oscillator and its mirror image
are obtained. The results are in agreement with those obtained by Bateman. At
last, the uncertainty relation are examined for above system.",0505147v1
2007-08-28,Pattern formation in the damped Nikolaevskiy equation,"The Nikolaevskiy equation has been proposed as a model for seismic waves,
electroconvection and weak turbulence; we show that it can also be used to
model transverse instabilities of fronts. This equation possesses a large-scale
""Goldstone"" mode that significantly influences the stability of spatially
periodic steady solutions; indeed, all such solutions are unstable at onset,
and the equation exhibits so-called soft-mode turbulence. In many applications,
a weak damping of this neutral mode will be present, and we study the influence
of this damping on solutions to the Nikolaevskiy equation. We examine the
transition to the usual Eckhaus instability as the damping of the large-scale
mode is increased, through numerical calculation and weakly nonlinear analysis.
The latter is accomplished using asymptotically consistent systems of coupled
amplitude equations. We find that there is a critical value of the damping
below which (for a given value of the supercriticality parameter) all periodic
steady states are unstable. The last solutions to lose stability lie in a cusp
close to the left-hand side of the marginal stability curve.",0708.3735v1
2008-01-12,Strong and weak coupling limits in optics of quantum well excitons,"A transition between the strong (coherent) and weak (incoherent) coupling
limits of resonant interaction between quantum well (QW) excitons and bulk
photons is analyzed and quantified as a function of the incoherent damping rate
caused by exciton-phonon and exciton-exciton scattering. For confined QW
polaritons, a second, anomalous, damping-induced dispersion branch arises and
develops with increasing damping. In this case, the strong-weak coupling
transition is attributed to a critical damping rate, when the intersection of
the normal and damping-induced dispersion branches occurs. For the radiative
states of QW excitons, i.e., for radiative QW polaritons, the transition is
described as a qualitative change of the photoluminescence spectrum at grazing
angles along the QW structure. Furthermore, we show that the radiative
corrections to the QW exciton states with in-plane wavevector approaching the
photon cone are universally scaled by an energy parameter rather than diverge.
The strong-weak coupling transition rates are also proportional to the same
energy parameter. The numerical evaluations are given for a GaAs single quantum
well with realistic parameters.",0801.1895v2
2008-01-22,Damped Bloch Oscillations of Bose-Einstein Condensates in Disordered Potential Gradients,"We investigate both experimentally and theoretically disorder induced damping
of Bloch oscillations of Bose-Einstein condensates in optical lattices. The
spatially inhomogeneous force responsible for the damping is realised by a
combination of a disordered optical and a magnetic gradient potential. We show
that the inhomogeneity of this force results in a broadening of the
quasimomentum spectrum, which in turn causes damping of the centre-of-mass
oscillation. We quantitatively compare the obtained damping rates to the
simulations using the Gross-Pitaevskii equation. Our results are relevant for
high precision experiments on very small forces, which require the observation
of a large number of oscillation cycles.",0801.3437v2
2008-02-26,"Fractional Langevin Equation: Over-Damped, Under-Damped and Critical Behaviors","The dynamical phase diagram of the fractional Langevin equation is
investigated for harmonically bound particle. It is shown that critical
exponents mark dynamical transitions in the behavior of the system. Four
different critical exponents are found. (i) $\alpha_c=0.402\pm 0.002$ marks a
transition to a non-monotonic under-damped phase, (ii) $\alpha_R=0.441...$
marks a transition to a resonance phase when an external oscillating field
drives the system, (iii) $\alpha_{\chi_1}=0.527...$ and (iv)
$\alpha_{\chi_2}=0.707...$ marks transition to a double peak phase of the
""loss"" when such an oscillating field present. As a physical explanation we
present a cage effect, where the medium induces an elastic type of friction.
Phase diagrams describing over-damped, under-damped regimes, motion and
resonances, show behaviors different from normal.",0802.3777v1
2008-04-26,Vibrational modes of metal nanoshells and bimetallic core-shell nanoparticles,"We study theoretically spectrum of radial vibrational modes in composite
metal nanostructures such as bimetallic core-shell particles and metal
nanoshells with dielectric core in an environment. We calculate frequencies and
damping rates of fundamental (breathing) modes for these nanostructures along
with those of two higher-order modes. For metal nanoshells, we find that the
breathing mode frequency is always lower than the one for solid particles of
the same size, while the damping is higher and increases with reduction of the
shell thickness. We identify two regimes that can be characterized as weakly
damped and overdamped vibrations in the presence of external medium. For
bimetalllic particles, we find periodic dependence of frequency and damping
rate on the shell thickness with period determined by mode number. For both
types of nanostructures, the frequency of higher modes is nearly independent of
the environment, while the damping rate shows strong sensitivity to outside
medium.",0804.4249v2
2008-09-26,Damping of the baryon acoustic oscillations in the matter power spectrum as a probe of the growth factor,"We investigate the damping of the baryon acoustic oscillations (BAO)
signature in the matter power spectrum due to the quasi-nonlinear clustering of
density perturbations. On the basis of the third order perturbation theory, we
construct a fitting formula of the damping in an analytic way. This
demonstrates that the damping is closely related with the growth factor and the
amplitude of the matter power spectrum. Then, we investigate the feasibility of
constraining the growth factor through a measurement of the damping of the BAO
signature. An extension of our formula including higher order corrections of
density perturbations is also discussed.",0809.4538v2
2008-10-07,Corotational Damping of Diskoseismic C-modes in Black Hole Accretion Discs,"Diskoseismic c-modes in accretion discs have been invoked to explain
low-frequency variabilities observed in black-hole X-ray binaries. These modes
are trapped in the inner-most region of the disc and have frequencies much
lower than the rotation frequency at the disc inner radius. We show that
because the trapped waves can tunnel through the evanescent barrier to the
corotational wave zone, the c-modes are damped due to wave absorption at the
corotation resonance. We calculate the corotational damping rates of various
c-modes using the WKB approximation. The damping rate varies widely depending
on the mode frequency, the black hole spin parameter and the disc sound speed,
and is generally much less than 10% of the mode frequency. A sufficiently
strong excitation mechanism is needed to overcome this corotational damping and
make the mode observable.",0810.1299v3
2008-10-10,Non-standard conserved Hamiltonian structures in dissipative/damped systems : Nonlinear generalizations of damped harmonic oscillator,"In this paper we point out the existence of a remarkable nonlocal
transformation between the damped harmonic oscillator and a modified Emden type
nonlinear oscillator equation with linear forcing, $\ddot{x}+\alpha
x\dot{x}+\beta x^3+\gamma x=0,$ which preserves the form of the time
independent integral, conservative Hamiltonian and the equation of motion.
Generalizing this transformation we prove the existence of non-standard
conservative Hamiltonian structure for a general class of damped nonlinear
oscillators including Li\'enard type systems. Further, using the above
Hamiltonian structure for a specific example namely the generalized modified
Emden equation $\ddot{x}+\alpha x^q\dot{x}+\beta x^{2q+1}=0$, where $\alpha$,
$\beta$ and $q$ are arbitrary parameters, the general solution is obtained
through appropriate canonical transformations. We also present the conservative
Hamiltonian structure of the damped Mathews-Lakshmanan oscillator equation. The
associated Lagrangian description for all the above systems is also briefly
discussed.",0810.1819v2
2008-11-05,R-matrix inner-shell electron-impact excitation of Fe$^{15+}$ including Auger-plus-radiation damping,"We present results for the inner-shell electron-impact excitation of
Fe$^{15+}$ using the intermediate-coupling frame transformation {\it R}-matrix
approach in which Auger-plus-radiation damping has been included. The target
and close-coupling expansions are both taken to be the 134 levels belonging to
the configurations ${\rm 2s^22p^63}l$, ${\rm 2s^22p^53s3}l$, ${\rm
2s^22p^53p^2}$ and ${\rm 2s^22p^53p3d}$. The comparison of Maxwell-averaged
effective collision strengths with and without damping shows that the damping
reduction is about 30-40% for many transitions at low temperatures, but up to
80% for a few transitions. As a consequence, the results of previous Dirac
$R$-matrix calculations (Aggarwal and Keenan, 2008) overestimate the effective
collision strengths due to their omission of Auger-plus-radiation damping.",0811.0750v1
2009-03-11,An alternate design for CLIC main linac wakefield suppression,"The present design of the main accelerating structure for CLIC is based on
heavy damping (WDS) with a Q of ~10. The wakefield suppression in this case
entails locating the damping materials in relatively close proximity to the
accelerating cells. Herein we present an alternate design for the main
accelerating structures. We detune the lowest dipole band by prescribing a
Gaussian distribution to the cell parameters and consider moderate damping
Q~500 to prevent the recoherence of the modes; in this case the damping
materials can be located at an extended distance from the accelerating
structure. The procedure to achieve a well-damped wakefield is described.
Results are presented elucidating the various designs including the current one
which is being developed to incorporate r.f. breakdown, pulse surface heating
and beam dynamics constraints.",0903.1935v1
2009-04-17,Revealing Sub-Surface Vibrational Modes by Atom-Resolved Damping Force Spectroscopy,"We propose to use the damping signal of an oscillating cantilever in dynamic
atomic force microscopy as a noninvasive tool to study the vibrational
structure of the substrate. We present atomically resolved maps of damping in
carbon nanotube peapods, capable of identifying the location and packing of
enclosed Dy@C82 molecules as well as local excitations of vibrational modes
inside nanotubes of different diameter. We elucidate the physical origin of
damping in a microscopic model and provide quantitative interpretation of the
observations by calculating the vibrational spectrum and damping of Dy@C82
inside nanotubes with different diameters using ab initio total energy and
molecular dynamics calculations.",0904.2666v1
2009-08-04,Time domain detection of pulsed spin torque damping reduction,"Combining multiple ultrafast spin torque impulses with a 5 nanosecond
duration pulse for damping reduction, we observe time-domain precession which
evolves from an initial 1 ns duration transient with changing precessional
amplitude to constant amplitude oscillations persisting for over 2 ns. These
results are consistent with relaxation of the transient trajectories to a
stable orbit with nearly zero damping. We find that in order to observe
complete damping cancellation and the transient behavior in a time domain
sampling measurement, a short duration, fast rise-time pulse is required to
cancel damping without significant trajectory dephasing.",0908.0481v1
2009-10-02,Damping of a nanomechanical oscillator strongly coupled to a quantum dot,"We present theoretical and experimental results on the mechanical damping of
an atomic force microscope cantilever strongly coupled to a self-assembled InAs
quantum dot. When the cantilever oscillation amplitude is large, its motion
dominates the charge dynamics of the dot which in turn leads to nonlinear,
amplitude-dependent damping of the cantilever. We observe highly asymmetric
lineshapes of Coulomb blockade peaks in the damping that reflect the degeneracy
of energy levels on the dot, in excellent agreement with our strong coupling
theory. Furthermore, we predict that excited state spectroscopy is possible by
studying the damping versus oscillation amplitude, in analogy to varying the
amplitude of an ac gate voltage.",0910.0308v1
2010-01-27,The spatial damping of magnetohydrodynamic waves in a flowing partially ionised prominence plasma,"Solar prominences are partially ionised plasmas displaying flows and
oscillations. These oscillations show time and spatial damping and, commonly,
have been explained in terms of magnetohydrodynamic (MHD) waves. We study the
spatial damping of linear non-adiabatic MHD waves in a flowing partially
ionised plasma, having prominence-like physical properties. We consider single
fluid equations for a partially ionised hydrogen plasma including in the energy
equation optically thin radiation, thermal conduction by electrons and
neutrals, and heating. Keeping the frequency real and fixed, we have solved the
obtained dispersion relations for the complex wavenumber, k, and have analysed
the behaviour of the damping length, wavelength and the ratio of the damping
length to the wavelength, versus period, for Alfven, fast, slow and thermal
waves.",1001.4962v1
2010-02-26,Correlation Effects in the Stochastic Landau-Lifshitz-Gilbert Equation,"We analyze the Landau-Lifshitz-Gilbert equation when the precession motion of
the magnetic moments is additionally subjected to an uniaxial anisotropy and is
driven by a multiplicative coupled stochastic field with a finite correlation
time $\tau$. The mean value for the spin wave components offers that the
spin-wave dispersion relation and its damping is strongly influenced by the
deterministic Gilbert damping parameter $\alpha$, the strength of the
stochastic forces $D$ and its temporal range $\tau$. The spin-spin-correlation
function can be calculated in the low correlation time limit by deriving an
evolution equation for the joint probability function. The stability analysis
enables us to find the phase diagram within the $\alpha-D$ plane for different
values of $\tau$ where damped spin wave solutions are stable. Even for zero
deterministic Gilbert damping the magnons offer a finite lifetime. We detect a
parameter range where the deterministic and the stochastic damping mechanism
are able to compensate each other leading to undamped spin-waves. The onset is
characterized by a critical value of the correlation time. An enhancement of
$\tau$ leads to an increase of the oscillations of the correlation function.",1002.4958v1
2010-03-04,Internal dissipation of a polymer,"The dynamics of flexible polymer molecules are often assumed to be governed
by hydrodynamics of the solvent. However there is considerable evidence that
internal dissipation of a polymer contributes as well. Here we investigate the
dynamics of a single chain in the absence of solvent to characterize the nature
of this internal friction. We model the chains as freely hinged but with
localized bond angles and 3-fold symmetric dihedral angles. We show that the
damping is close but not identical to Kelvin damping, which depends on the
first temporal and second spatial derivative of monomer position. With no
internal potential between monomers, the magnitude of the damping is small for
long wavelengths and weakly damped oscillatory time dependent behavior is seen
for a large range of spatial modes. When the size of the internal potential is
increased, such oscillations persist, but the damping becomes larger. However
underdamped motion is present even with quite strong dihedral barriers for long
enough wavelengths.",1003.0944v2
2010-06-09,Synchrotron oscillation damping due to beam-beam collisions,"In DA{\Phi}NE, the Frascati e+/e- collider, the crab waist collision scheme
has been successfully implemented in 2008 and 2009. During the collision
operations for Siddharta experiment, an unusual synchrotron damping effect has
been observed. Indeed, with the longitudinal feedback switched off, the
positron beam becomes unstable with beam currents in the order of 200-300 mA.
The longitudinal instability is damped by bringing the positron beam in
collision with a high current electron beam (~2A). Besides, we have observed a
shift of \approx 600Hz in the residual synchrotron sidebands. Precise
measurements have been performed by using both a commercial spectrum analyzer
and the diagnostics capabilities of the DA{\Phi}NE longitudinal bunch-by-bunch
feedback. This damping effect has been observed in DA{\Phi}NE for the first
time during collisions with the crab waist scheme. Our explanation is that beam
collisions with a large crossing angle produce a longitudinal tune shift and a
longitudinal tune spread, providing Landau damping of synchrotron oscillations.",1006.1783v1
2010-06-30,Landau Damping of Baryon Structure Formation in the Post Reionization Epoch,"It has been suggested by Chen and Lai that the proper description of the
large scale structure formation of the universe in the post-reionization era,
which is conventionally characterized via gas hydrodynamics, should include the
plasma collective effects in the formulation. Specifically, it is the combined
pressure from the baryon thermal motions and the residual long-range
electrostatic potentials resulted from the imperfect Debye shielding, that
fights against the gravitational collapse. As a result, at small-scales the
baryons would oscillate at the ion-acoustic, instead of the conventional
neutral acoustic, frequency. In this paper we extend and improve the Chen-Lai
formulation with the attention to the Landau damping of the ion-acoustic
oscillations. Since T_e \sim T_i in the post-reionization era, the ion acoustic
oscillations would inevitably suffer the Landau damping which severely
suppresses the baryon density spectrum in the regimes of intermediate and high
wavenumber k. To describe this Landau-damping phenomenon more appropriately, we
find it necessary to modify the filtering wavenumber k_f in our analysis. It
would be interesting if our predicted Landau damping of the ion-acoustic
oscillations can be observed at high redshifts.",1006.5777v1
2010-07-12,Passive damping of beam vibrations through distributed electric networks and piezoelectric transducers: prototype design and experimental validation,"The aim of this work is two-fold: to design devices for passive electric
damping of structural vibrations by distributed piezoelectric transducers and
electric networks, and to experimentally validate the effectiveness of such a
damping concept. Two different electric networks are employed, namely a purely
resistive network and an inductive-resistive one. The presented devices can be
considered as distributed versions of the well-known resistive and resonant
shunt of a single piezoelectric transducer. The technicalfeasibility and
damping effectiveness of the proposed novel devices are assessed through the
construction of an experimental prototype. Experimental results are shown to be
in very good agreement with theoretical predictions. It is proved that the
presented technique allows for a substantial reduction in the inductances used
when compared with those required by the single resonant shunted transducer. In
particular, it is shown that the required inductance decreases when the number
of piezoelectric elements is increased. The electric networks are optimized in
order to reduce forced vibrations close to the first resonance frequency.
Nevertheless, the damping effectiveness for higher modes is experimentally
proved. As well as specific results, fundamental theoretical and experimental
considerations for passive distributed vibration control are provided.",1007.1863v1
2010-07-23,Highly-damped quasi-normal frequencies for piecewise Eckart potentials,"Highly-damped quasi-normal frequencies are very often of the form omega_n =
(offset) + i n (gap). We investigate the genericity of this phenomenon by
considering a model potential that is piecewise Eckart (piecewise
Poeschl-Teller), and developing an analytic ""quantization condition"" for the
highly-damped quasi-normal frequencies. We find that this omega_n = (offset) +
i n (gap) behaviour is generic but not universal, with the controlling feature
being whether or not the ratio of the rates of exponential falloff in the two
asymptotic directions is a rational number. These observations are of direct
relevance to any physical situation where highly-damped quasi-normal modes
(damped modes) are important --- in particular (but not limited to) to black
hole physics, both theoretical and observational.",1007.4039v2
2010-09-23,Asymptotic Spectrum of Kerr Black Holes in the Small Angular Momentum Limit,"We study analytically the highly damped quasinormal modes of Kerr black holes
in the small angular momentum limit. To check the previous analytic
calculations in the literature, which use a combination of radial and tortoise
coordinates, we reproduce all the results using the radial coordinate only.
According to the earlier calculations, the real part of the highly damped
quasinormal mode frequency of Kerr black holes approaches zero in the limit
where the angular momentum goes to zero. This result is not consistent with the
Schwarzschild limit where the real part of the highly damped quasinormal mode
frequency is equal to c^3 ln(3)/(8 pi G M). In this paper, our calculations
suggest that the highly damped quasinormal modes of Kerr black holes in the
zero angular momentum limit make a continuous transition from the Kerr value to
the Schwarzschild value. We explore the nature of this transition using a
combination of analytical and numerical techniques. Finally, we calculate the
highly damped quasinormal modes of the extremal case in which the topology of
Stokes/anti-Stokes lines takes a different form.",1009.4632v2
2010-12-31,Exact Tkachenko modes and their damping in the vortex lattice regime of rapidly rotating bosons,"We have found an exact analytical solution of the Bogoliubov-de Gennes
equations for the Tkachenko modes of the vortex lattice in the lowest Landau
level (LLL) in the thermodynamic limit at any momenta and calculated their
damping rates. At finite temperatures both Beliaev and Landau damping leads to
momentum independent damping rates in the low-energy limit, which shows that at
sufficiently low energies Tkachenko modes become strongly damped. We then found
that the mean square fluctuations of the density grow logarithmically at large
distances, which indicates that the state is ordered in the vortex lattice only
on a finite (although exponentially large) distance scale and introduces a
low-momentum cut-off. Using this circumstance we showed that at finite
temperatures the one-body density matrix undergoes an exponential decay at
large distances.",1101.0269v1
2011-01-20,Decoherence and entanglement degradation of a qubit-qutrit system in non-inertial frames,"We study the effect of decoherence on a qubit-qutrit system under the
influence of global, local and multilocal decoherence in non-inertial frames.
We show that the entanglement sudden death can be avoided in non-inertial
frames in the presence of amplitude damping, depolarizing and phase damping
channels. However, degradation of entanglement is seen due to Unruh effect. It
is shown that for lower level of decoherence, the depolarizing channel degrades
the entanglement more heavily as compared to the amplitude damping and phase
damping channels. However, for higher values of decoherence parameters,
amplitude damping channel heavily degrades the entanglement of the hybrid
system. Further more, no ESD is seen for any value of Rob's acceleration.",1101.3986v1
2011-06-23,Ratchet effect on a relativistic particle driven by external forces,"We study the ratchet effect of a damped relativistic particle driven by both
asymmetric temporal bi-harmonic and time-periodic piecewise constant forces.
This system can be formally solved for any external force, providing the
ratchet velocity as a non-linear functional of the driving force. This allows
us to explicitly illustrate the functional Taylor expansion formalism recently
proposed for this kind of systems. The Taylor expansion reveals particularly
useful to obtain the shape of the current when the force is periodic, piecewise
constant. We also illustrate the somewhat counterintuitive effect that
introducing damping may induce a ratchet effect. When the force is symmetric
under time-reversal and the system is undamped, under symmetry principles no
ratchet effect is possible. In this situation increasing damping generates a
ratchet current which, upon increasing the damping coefficient eventually
reaches a maximum and decreases toward zero. We argue that this effect is not
specific of this example and should appear in any ratchet system with tunable
damping driven by a time-reversible external force.",1106.4861v1
2011-07-17,Nonlinear-damping continuation of the nonlinear Schrödinger equation - a numerical study,"We study the nonlinear-damping continuation of singular solutions of the
critical and supercritical NLS. Our simulations suggest that for generic
initial conditions that lead to collapse in the undamped NLS, the solution of
the weakly-damped NLS $$
i\psi_t(t,\X)+\Delta\psi+|\psi|^{p-1}\psi+i\delta|\psi|^{q-1}\psi=0,\qquad0<\delta
\ll 1, $$ is highly asymmetric with respect to the singularity time, and the
post-collapse defocusing velocity of the singular core goes to infinity as the
damping coefficient $\delta$ goes to zero. In the special case of the
minimal-power blowup solutions of the critical NLS, the continuation is a
minimal-power solution with a higher (but finite) defocusing velocity, whose
magnitude increases monotonically with the nonlinear damping exponent $q$.",1107.3281v1
2011-10-05,Radiation damping in pulsed Gaussian beams,"We consider the effects of radiation damping on the electron dynamics in a
Gaussian beam model of a laser field. For high intensities, i.e. with
dimensionless intensity a0 \gg 1, it is found that the dynamics divide into
three regimes. For low energy electrons (low initial {\gamma}-factor,
{\gamma}0) the radiation damping effects are negligible. At higher energies,
but still at 2{\gamma}0 < a0, the damping alters the final displacement and the
net energy change of the electron. For 2{\gamma}0 > a0 one is in a regime of
radiation reaction induced electron capture. This capture is found to be stable
with respect to the spatial properties of the electron beam and results in a
significant energy loss of the electrons. In this regime the plane wave model
of the laser field provides a good description of the dynamics, whereas for
lower energies the Gaussian beam and plane wave models differ significantly.
Finally the dynamics are considered for the case of an XFEL field. It is found
that the significantly lower intensities of such fields inhibits the damping
effects.",1110.0996v1
2012-03-28,Analysis of the absorbing layers for the weakly-compressible lattice Boltzmann schemes,"It has been demonstrated that Lattice Boltzmann schemes (LBSs) are very
efficient for Computational AeroAcoustics (CAA). In order to handle the issue
of absorbing acoustic boundary conditions for LBS, three kinds of damping terms
are proposed and added into the right hand sides of the governing equations of
LBS. From the classical theory, these terms play an important role to absorb
and minimize the acoustic wave reflections from computational boundaries.
Meanwhile, the corresponding macroscopic equations with the damping terms are
recovered for analyzing the macroscopic behaviors of the these damping terms
and determining the critical absorbing strength. Further, in order to detect
the dissipation and dispersion behaviors, the linearized LBS with the damping
terms is derived and analyzed. The dispersive and dissipative properties are
explored in the wave-number spaces via the Von Neumann analysis. The related
damping strength critical values and the optimal absorbing term are addressed.
Finally, some benchmark problems are implemented to assess the theoretical
results.",1203.6350v1
2012-06-05,Existence and exponential stability of a damped wave equation with dynamic boundary conditions and a delay term,"In this paper we consider a multi-dimensional wave equation with dynamic
boundary conditions related to the Kelvin-Voigt damping and a delay term acting
on the boundary. If the weight of the delay term in the feedback is less than
the weight of the term without delay or if it is greater under an assumption
between the damping factor, and the difference of the two weights, we prove the
global existence of the solutions. Under the same assumptions, the exponential
stability of the system is proved using an appropriate Lyapunov functional.
More precisely, we show that even when the weight of the delay is greater than
the weight of the damping in the boundary conditions, the strong damping term
still provides exponential stability for the system.",1206.1010v1
2012-08-27,Analysis of the damped quantum search and its application to the one-dimensional Ising system,"An analysis on the damped quantum search by exploring the rate at which the
target state is obtained. The results were compared with that of the classical
search since the standard Grover's algorithm does not give a convergent result
if the number of target state is unknown. For a large number of target states,
the classical and the damped quantum search give a similar result. However, for
intermediate values of the target size the damped quantum search gives a higher
probability of success than the classical search. Furthermore, we also made an
analysis on the average number of iterations needed to obtain at least one of
the target states. As the number of target states is reduced, the damped
quantum search gives a better result than the classical search. The results
coincide if the size of target state is comparable to the size of the sample.",1208.5509v1
2012-10-20,Radiative damping of surface plasmon resonance in spheroidal metallic nanoparticle embedded in a dielectric medium,"The local field approach and kinetic equation method is applied to calculate
the surface plasmon radiative damping in a spheroidal metal nanoparticle
embedded in any dielectric media. The radiative damping of the surface plasmon
resonance as a function of the particle radius, shape, dielectric constant of
the surrounding medium and the light frequency is studied in detail. It is
found that the radiative damping grows quadratically with the particle radius
and oscillates with altering both the particle size and the dielectric constant
of a surrounding medium. Much attention is paid to the electron
surface-scattering contribution to the plasmon decay. All calculations of the
radiative damping are illustrated by examples on the Au and Na nanoparticles.",1210.5647v1
2012-11-11,Dissipation in relativistic superfluid neutron stars,"We analyze damping of oscillations of general relativistic superfluid neutron
stars. To this aim we extend the method of decoupling of superfluid and normal
oscillation modes first suggested in [Gusakov & Kantor PRD 83, 081304(R)
(2011)]. All calculations are made self-consistently within the finite
temperature superfluid hydrodynamics. The general analytic formulas are derived
for damping times due to the shear and bulk viscosities. These formulas
describe both normal and superfluid neutron stars and are valid for oscillation
modes of arbitrary multipolarity. We show that: (i) use of the ordinary
one-fluid hydrodynamics is a good approximation, for most of the stellar
temperatures, if one is interested in calculation of the damping times of
normal f-modes; (ii) for radial and p-modes such an approximation is poor;
(iii) the temperature dependence of damping times undergoes a set of rapid
changes associated with resonance coupling of neighboring oscillation modes.
The latter effect can substantially accelerate viscous damping of normal modes
in certain stages of neutron-star thermal evolution.",1211.2452v1
2013-03-07,Universal damping behavior of dipole oscillations of one-dimensional ultracold gases induced by quantum phase slips,"We study superflow decay via quantum phase slips in trapped one-dimensional
(1D) quantum gases through dipole oscillations induced by sudden displacement
of the trapping potential. We find the relation between the damping rate of the
dipole oscillation $G$ and the phase-slip nucleation rate $\Gamma$ as $G\propto
\Gamma/v$, where $v$ is the flow velocity. This relation allows us to show that
damping of 1D Bose gases in optical lattices, which has been extensively
studied in experiment, is due to quantum phase slips. It is also found that the
damping rate versus the flow velocity obeys the scaling formula for an impurity
potential even in the absence of an explicit impurity. We suggest that the
damping rate at a finite temperature exhibits a universal crossover behavior
upon changing the flow velocity.",1303.1616v1
2013-07-16,Blow-up of solutions to the one-dimensional semilinear wave equation with damping depending on time and space variables,"In this paper, we give a small data blow-up result for the one-dimensional
semilinear wave equation with damping depending on time and space variables. We
show that if the damping term can be regarded as perturbation, that is,
non-effective damping in a certain sense, then the solution blows up in finite
time for any power of nonlinearity. This gives an affirmative answer for the
conjecture that the critical exponent agrees with that of the wave equation
when the damping is non-effective in one space dimension.",1307.4260v2
2013-11-12,Landau damping: paraproducts and Gevrey regularity,"We give a new, simpler, proof of nonlinear Landau damping on T^d in
Gevrey-1/s regularity (s > 1/3) which matches the regularity requirement
predicted by the formal analysis of Mouhot and Villani in the original proof of
Landau damping [Acta Mathematica 2011]. Our proof combines in a novel way ideas
from the original proof of Landau damping and the proof of inviscid damping in
2D Euler [arXiv:1306.5028]. As in the work on 2D Euler, we use paraproduct
decompositions and controlled regularity loss to replace the Newton iteration
scheme employed in the original proof. We perform time-response estimates
adapted from the original proof to control the plasma echoes and couple them to
energy estimates on the distribution function in the style of the work on 2D
Euler.",1311.2870v1
2014-02-07,One-dimensional random attractor and rotation number of the stochastic damped sine-Gordon equation,"This paper is devoted to the study of the asymptotic dynamics of the
stochastic damped sine-Gordon equation with homogeneous Neumann boundary
condition. It is shown that for any positive damping and diffusion
coefficients, the equation possesses a random attractor, and when the damping
and diffusion coefficients are sufficiently large, the random attractor is a
one-dimensional random horizontal curve regardless of the strength of noise.
Hence its dynamics is not chaotic. It is also shown that the equation has a
rotation number provided that the damping and diffusion coefficients are
sufficiently large, which implies that the solutions tend to oscillate with the
same frequency eventually and the so called frequency locking is successful.",1402.1787v1
2014-02-26,Comparison of methods for numerical calculation of continuum damping,"Continuum resonance damping is an important factor in determining the
stability of certain global modes in fusion plasmas. A number of analytic and
numerical approaches have been developed to compute this damping, particularly
in the case of the toroidicity-induced shear Alfv\'en eigenmode. This paper
compares results obtained using an analytical perturbative approach with those
found using resistive and complex contour numerical approaches. It is found
that the perturbative method does not provide accurate agreement with reliable
numerical methods for the range of parameters examined. This discrepancy exists
even in the limit where damping approaches zero. When the perturbative
technique is implemented using a standard finite element method, the damping
estimate fails to converge with radial grid resolution. The finite elements
used cannot accurately represent the eigenmode in the region of the continuum
resonance, regardless of the number of radial grid points used.",1402.6389v1
2014-07-08,Fourier-Hermite spectral representation for the Vlasov-Poisson system in the weakly collisional limit,"We study Landau damping in the 1+1D Vlasov-Poisson system using a
Fourier-Hermite spectral representation. We describe the propagation of free
energy in phase space using forwards and backwards propagating Hermite modes
recently developed for gyrokinetics [Schekochihin et al. (2014)]. The change in
the electric field corresponds to the net Hermite flux via a free energy
evolution equation. In linear Landau damping, decay in the electric field
corresponds to forward propagating Hermite modes; in nonlinear damping, the
initial decay is followed by a growth phase characterised by the generation of
backwards propagating Hermite modes by the nonlinear term. The free energy
content of the backwards propagating modes increases exponentially until
balancing that of the forward propagating modes. Thereafter there is no
systematic net Hermite flux, so the electric field cannot decay and the
nonlinearity effectively suppresses Landau damping. These simulations are
performed using the fully-spectral 5D gyrokinetics code SpectroGK [Parker et
al. 2014], modified to solve the 1+1D Vlasov-Poisson system. This captures
Landau damping via an iterated L\'enard-Bernstein collision operator or via
Hou-Li filtering in velocity space. Therefore the code is applicable even in
regimes where phase-mixing and filamentation are dominant.",1407.1932v1
2014-08-15,Linear hyperbolic equations with time-dependent propagation speed and strong damping,"We consider a second order linear equation with a time-dependent coefficient
c(t) in front of the ""elastic"" operator. For these equations it is well-known
that a higher space-regularity of initial data compensates a lower
time-regularity of c(t).
  In this paper we investigate the influence of a strong dissipation, namely a
friction term which depends on a power of the elastic operator.
  What we discover is a threshold effect. When the exponent of the elastic
operator in the friction term is greater than 1/2, the damping prevails and the
equation behaves as if the coefficient c(t) were constant. When the exponent is
less than 1/2, the time-regularity of c(t) comes into play. If c(t) is regular
enough, once again the damping prevails. On the contrary, when c(t) is not
regular enough the damping might be ineffective, and there are examples in
which the dissipative equation behaves as the non-dissipative one. As expected,
the stronger is the damping, the lower is the time-regularity threshold.
  We also provide counterexamples showing the optimality of our results.",1408.3499v1
2014-08-14,Particle Dynamics in Damped Nonlinear Quadrupole Ion Traps,"We examine the motions of particles in quadrupole ion traps as a function of
damping and trapping forces, including cases where nonlinear damping or
nonlinearities in the electric field geometry play significant roles. In the
absence of nonlinearities, particles are either damped to the trap center or
ejected, while their addition brings about a rich spectrum of stable closed
particle trajectories. In three-dimensional (3D) quadrupole traps, the extended
orbits are typically confined to the trap axis, and for this case we present a
1D analysis of the relevant equation of motion. We follow this with an analysis
of 2D quadrupole traps that frequently show diamond-shaped closed orbits. For
both the 1D and 2D cases we present experimental observations of the calculated
trajectories in microparticle ion traps. We also report the discovery of a new
collective behavior in damped 2D microparticle ion traps, where particles
spontaneously assemble into a remarkable knot of overlapping, corotating
diamond orbits, self-stabilized by air currents arising from the particle
motion.",1409.6262v1
2015-01-03,Finite-Parameters Feedback Control for Stabilizing Damped Nonlinear Wave Equations,"In this paper we introduce a finite-parameters feedback control algorithm for
stabilizing solutions of various classes of damped nonlinear wave equations.
Specifically, stabilization the zero steady state solution of initial boundary
value problems for nonlinear weakly and strongly damped wave equations,
nonlinear wave equation with nonlinear damping term and some related nonlinear
wave equations, introducing a feedback control terms that employ parameters,
such as, finitely many Fourier modes, finitely many volume elements and
finitely many nodal observables and controllers. In addition, we also establish
the stabilization of the zero steady state solution to initial boundary value
problem for the damped nonlinear wave equation with a controller acting in a
proper subdomain. Notably, the feedback controllers proposed here can be
equally applied for stabilizing other solutions of the underlying equations.",1501.00556v1
2015-06-26,A Universal Damping Mechanism of Quantum Vibrations in Deep Sub-Barrier Fusion Reactions,"We demonstrate the damping of quantum octupole vibrations near the touching
point when two colliding nuclei approach each other in the mass-asymmetric
$^{208}$Pb + $^{16}$O system, for which the strong fusion hindrance was clearly
observed. We, for the first time, apply the random-phase approximation method
to the heavy-mass asymmetric di-nuclear system to calculate the transition
strength $B$(E3) as a function of the center-of-mass distance. The obtained
$B$(E3) strengths are substantially damped near the touching point, because the
single-particle wave functions of the two nuclei strongly mix with each other
and a neck is formed. The energy-weighted sums of $B$(E3) are also strongly
correlated with the damping factor which is phenomenologically introduced in
the standard coupled-channel calculations to reproduce the fusion hindrance.
This strongly indicates that the damping of the quantum vibrations universally
occurs in the deep sub-barrier fusion reactions.",1506.07963v1
2015-07-28,Phenomenology of chiral damping in noncentrosymmetric magnets,"A phenomenology of magnetic chiral damping is proposed in the context of
magnetic materials lacking inversion symmetry breaking. We show that the
magnetic damping tensor adopts a general form that accounts for a component
linear in magnetization gradient in the form of Lifshitz invariants. We propose
different microscopic mechanisms that can produce such a damping in
ferromagnetic metals, among which spin pumping in the presence of anomalous
Hall effect and an effective ""$s$-$d$"" Dzyaloshinskii-Moriya antisymmetric
exchange. The implication of this chiral damping in terms of domain wall motion
is investigated in the flow and creep regimes. These predictions have major
importance in the context of field- and current-driven texture motion in
noncentrosymmetric (ferro-, ferri-, antiferro-)magnets, not limited to metals.",1507.07762v1
2015-08-06,"Phenomenological description of the nonlocal magnetization relaxation in magnonics, spintronics, and domain-wall dynamics","A phenomenological equation called Landau-Lifshitz-Baryakhtar (LLBar)
equation, which could be viewed as the combination of Landau-Lifshitz (LL)
equation and an extra ""exchange damping"" term, was derived by Baryakhtar using
Onsager's relations. We interpret the origin of this ""exchange damping"" as
nonlocal damping by linking it to the spin current pumping. The LLBar equation
is investigated numerically and analytically for the spin wave decay and domain
wall motion. Our results show that the lifetime and propagation length of
short-wavelength magnons in the presence of nonlocal damping could be much
smaller than those given by LL equation. Furthermore, we find that both the
domain wall mobility and the Walker breakdown field are strongly influenced by
the nonlocal damping.",1508.01478v1
2015-11-13,Magnified Damping under Rashba Spin Orbit Coupling,"The spin orbit coupling spin torque consists of the field-like [REF: S.G. Tan
et al., arXiv:0705.3502, (2007).] and the damping-like terms [REF: H.
Kurebayashi et al., Nature Nanotechnology 9, 211 (2014).] that have been widely
studied for applications in magnetic memory. We focus, in this article, not on
the spin orbit effect producing the above spin torques, but on its magnifying
the damping constant of all field like spin torques. As first order precession
leads to second order damping, the Rashba constant is naturally co-opted,
producing a magnified field-like damping effect. The Landau-Liftshitz-Gilbert
equations are written separately for the local magnetization and the itinerant
spin, allowing the progression of magnetization to be self-consistently locked
to the spin.",1511.04227v1
2016-01-05,Vlasov Simulations of Electron-Ion Collision Effects on Damping of Electron Plasma Waves,"Collisional effects can play an essential role in the dynamics of plasma
waves by setting a minimum damping rate and by interfering with wave-particle
resonances. Kinetic simulations of the effects of electron-ion pitch angle
scattering on Electron Plasma Waves (EPWs) are presented here. In particular,
the effects of such collisions on the frequency and damping of small-amplitude
EPWs for a range of collision rates and wave phase velocities are computed and
compared with theory. Both the Vlasov simulations and linear kinetic theory
find the direct contribution of electron-ion collisions to wave damping is
about a factor of two smaller than is obtained from linearized fluid theory. To
our knowledge, this simple result has not been published before.
  Simulations have been carried out using a grid-based (Vlasov) approach, based
on a high-order conservative finite difference method for discretizing the
Fokker-Planck equation describing the evolution of the electron distribution
function. Details of the implementation of the collision operator within this
framework are presented. Such a grid-based approach, which is not subject to
numerical noise, is of particular interest for the accurate measurements of the
wave damping rates.",1601.01002v1
2016-02-13,The effect of orbital damping during planet migration on the Inclination and Eccentricity Distributions of Neptune Trojans,"We explore planetary migration scenarios for formation of high inclination
Neptune Trojans (NTs) and how they are affected by the planetary migration of
Neptune and Uranus. If Neptune and Uranus's eccentricity and inclination were
damped during planetary migration, then their eccentricities and inclinations
were higher prior and during migration than their current values. Using test
particle integrations we study the stability of primordial NTs, objects that
were initially Trojans with Neptune prior to migration. We also study
Trans-Neptunian objects captured into resonance with Neptune and becoming NTs
during planet migration. We find that most primordial NTs were unstable and
lost if eccentricity and inclination damping took place during planetary
migration. With damping, secular resonances with Neptune can increase a low
eccentricity and inclination population of Trans-Neptunian objects increasing
the probability that they are captured into 1:1 resonance with Neptune,
becoming high inclination NTs. We suggest that the resonant trapping scenario
is a promising and more effective mechanism explaining the origin of NTs that
is particularly effective if Uranus and Neptune experienced eccentricity and
inclination damping during planetary migration.",1602.04303v1
2016-03-08,Damping of the Higgs and Nambu-Goldstone modes of superfluid Bose gases at finite temperatures,"We study collective modes of superfluid Bose gases in optical lattices at
commensurate fillings. We focus on the vicinity of the quantum phase transition
to the Mott insulator, where there exists the Higgs amplitude mode in addition
to the Nambu-Goldstone phase mode associated with the spontaneous U(1) symmetry
breaking. We analyze finite-temperature effects on the damping of the
collective modes by using an effective spin-1 model and the field theoretical
methods based on the finite-temperature Green's function. We calculate the
damping rates up to 1-loop order and evaluate them analytically and
numerically. We show that the damping rate of the Higgs mode increases with
increasing the temperature but it remains underdamped up to a typical
temperature achieved in experiments. Moreover, we find that the Nambu-Goldstone
mode attenuates via a Landau damping process resulting from interactions with
the Higgs mode and it can be overdamped at the typical temperature in a certain
parameter region.",1603.02395v1
2016-04-12,Offline software for the DAMPE experiment,"A software system has been developed for the DArk Matter Particle Explorer
(DAMPE) mission, a satellite-based experiment. The DAMPE software is mainly
written in C++ and steered using Python script. This article presents an
overview of the DAMPE offline software, including the major architecture design
and specific implementation for simulation, calibration and reconstruction. The
whole system has been successfully applied to DAMPE data analysis, based on
which some results from simulation and beam test experiments are obtained and
presented.",1604.03219v6
2016-04-18,Stabilization of Damped Waves on Spheres and Zoll Surfaces of Revolution,"We study the strong stabilization of wave equations on some sphere-like
manifolds, with rough damping terms which do not satisfy the geometric control
condition posed by Rauch-Taylor and Bardos-Lebeau-Rauch. We begin with an
unpublished result of G. Lebeau, which states that on S^d , the indicator
function of the upper hemisphere strongly stabilizes the damped wave equation,
even though the equators, which are geodesics contained in the boundary of the
upper hemisphere, do not enter the damping region. Then we extend this result
on dimension 2, to Zoll surfaces of revolution, whose geometry is similar to
that of S^2 . In particular, geometric objects such as the equator, and the
hemi-surfaces are well defined. Our result states that the indicator function
of the upper hemi-surface strongly stabilizes the damped wave equation, even
though the equator, as a geodesic, does not enter the upper hemi-surface
either.",1604.05218v2
2016-07-25,Damping of parametrically excited magnons in the presence of the longitudinal spin Seebeck effect,"The impact of the longitudinal spin Seebeck effect (LSSE) on the magnon
damping in magnetic-insulator/nonmagnetic-metal bilayers was recently discussed
in several reports. However, results of those experiments can be blurred by
multimode excitation within the measured linewidth. In order to avoid possible
intermodal interference, we investigated the damping of a single magnon group
in a platinum covered Yttrium Iron Garnet (YIG) film by measurement of the
threshold of its parametric excitation. Both dipolar and exchange spin-wave
branches were probed. It turned out that the LSSE-related modification of
spin-wave damping in a micrometer-thick YIG film is too weak to be observed in
the entire range of experimentally accessible wavevectors. At the same time,
the change in the mean temperature of the YIG layer, which can appear by
applying a temperature gradient, strongly modifies the damping value.",1607.07274v1
2016-07-27,Frequency dispersion of small-amplitude capillary waves in viscous fluids,"This work presents a detailed study of the dispersion of capillary waves with
small amplitude in viscous fluids using an analytically derived solution to the
initial value problem of a small-amplitude capillary wave as well as direct
numerical simulation. A rational parametrization for the dispersion of
capillary waves in the underdamped regime is proposed, including predictions
for the wavenumber of critical damping based on a harmonic oscillator model.
The scaling resulting from this parametrization leads to a self-similar
solution of the frequency dispersion of capillary waves that covers the entire
underdamped regime, which allows an accurate evaluation of the frequency at a
given wavenumber, irrespective of the fluid properties. This similarity also
reveals characteristic features of capillary waves, for instance that critical
damping occurs when the characteristic timescales of dispersive and dissipative
mechanisms are balanced. In addition, the presented results suggest that the
widely adopted hydrodynamic theory for damped capillary waves does not
accurately predict the dispersion when viscous damping is significant and a new
definition of the damping rate, which provides consistent accuracy in the
underdamped regime, is presented.",1607.08266v1
2016-10-18,On the stability of the Bresse system with frictional damping,"In this paper, we consider the Bresse system with frictional damping terms
and prove some optimal decay results for the $L^2$-norm of the solution and its
higher order derivatives. In fact, if we consider just one damping term acting
on the second equation of the solution, we show that the solution does not
decay at all. On the other hand, by considering one damping term alone acting
on the third equation, we show that this damping term is strong enough to
stabilize the whole system. In this case, we found a completely new stability
number that depends on the parameters in the system.
  In addition, we prove the optimality of the results by using eigenvalues
expansions. Our obtained results have been proved under some assumptions on the
wave speeds of the three equations in the Bresse system.",1610.05500v2
2017-02-17,Transition of multi-diffusive states in a biased periodic potential,"We study a frequency-dependent damping model of hyper-diffusion within the
generalized Langevin equation. The model allows for the colored noise defined
by its spectral density, assumed to be proportional to $\omega^{\delta-1}$ at
low frequencies with $0<\delta<1$ (sub-Ohmic damping) or $1<\delta<2$
(super-Ohmic damping), where the frequency-dependent damping is deduced from
the noise by means of the fluctuation-dissipation theorem. It is shown that for
super-Ohmic damping and certain parameters, the diffusive process of the
particle in a titled periodic potential undergos sequentially four
time-regimes: thermalization, hyper-diffusion, collapse and asymptotical
restoration. For analysing transition phenomenon of multi-diffusive states, we
demonstrate that the first exist time of the particle escaping from the locked
state into the running state abides by an exponential distribution. The concept
of equivalent velocity trap is introduced in the present model, moreover,
reformation of ballistic diffusive system is also considered as a marginal
situation, however there does not exhibit the collapsed state of diffusion.",1702.05370v1
2018-02-20,The damped wave equation with unbounded damping,"We analyze new phenomena arising in linear damped wave equations on unbounded
domains when the damping is allowed to become unbounded at infinity. We prove
the generation of a contraction semigroup, study the relation between the
spectra of the semigroup generator and the associated quadratic operator
function, the convergence of non-real eigenvalues in the asymptotic regime of
diverging damping on a subdomain, and we investigate the appearance of
essential spectrum on the negative real axis. We further show that the presence
of the latter prevents exponential estimates for the semigroup and turns out to
be a robust effect that cannot be easily canceled by adding a positive
potential. These analytic results are illustrated by examples.",1802.07026v1
2018-04-06,Exponential Integrators Preserving Local Conservation Laws of PDEs with Time-Dependent Damping/Driving Forces,"Structure-preserving algorithms for solving conservative PDEs with added
linear dissipation are generalized to systems with time-dependent
damping/driving terms. This study is motivated by several PDE models of
physical phenomena, such as Korteweg-de Vries, Klein-Gordon, Schr\""{o}dinger,
and Camassa-Holm equations, all with damping/driving terms and time-dependent
coefficients. Since key features of the PDEs under consideration are described
by local conservation laws, which are independent of the boundary conditions,
the proposed (second-order in time) discretizations are developed with the
intent of preserving those local conservation laws. The methods are
respectively applied to a damped-driven nonlinear Schr\""{o}dinger equation and
a damped Camassa-Holm equation. Numerical experiments illustrate the
structure-preserving properties of the methods, as well as favorable results
over other competitive schemes.",1804.02266v1
2018-11-21,Super Damping of Mechanical Vibrations,"We report the phenomenon of coherent super decay, where a linear sum of
several damped oscillators can collectively decay much faster than the
individual ones in the first stage, followed by stagnating ones after more than
90 percent of the energy has already been dissipated. The parameters of the
damped oscillators for CSD are determined by the process of response function
decomposition, which is to use several slow decay response functions to
approximate the response function of a fast decay reference resonator. Evidence
established in experiments and in finite element simulations not only strongly
supported the numerical investigations, but also uncovered an unexplored region
of the tuned mass damper parameter space where TMDs with total mass less than
0.2 percent of a primary free body can damp its first resonance up to a damping
ratio of 4.6 percent. Our findings also shed light onto the intriguing
underline connections between complex functions with different singular points.",1811.08621v2
2018-11-29,Flowing fibers as a proxy of turbulence statistics,"The flapping states of a flexible fiber fully coupled to a three-dimensional
turbulent flow are investigated via state-of-the-art numerical methods. Two
distinct flapping regimes are predicted by the phenomenological theory recently
proposed by Rosti et al. [Phys. Rev. Lett. 121, 044501, 2018]: the under-damped
regime, where the elasticity strongly affects the fiber dynamics, and the
over-damped regime, where the elastic effects are strongly inhibited. In both
cases we can identify a critical value of the bending rigidity of the fiber by
a resonance condition, which further provides a distinction between different
flapping behaviors, especially in the under-damped case. We validate the theory
by means of direct numerical simulations and find that, both for the
over-damped regime and for the under-damped one, fibers are effectively slaved
to the turbulent fluctuations and can therefore be used as a proxy to measure
various two-point statistics of turbulence. Finally, we show that this holds
true also in the case of a passive fiber, without any feedback force on the
fluid.",1811.12023v2
2018-11-29,The Lugiato-Lefever equation with nonlinear damping caused by two photon absorption,"In this paper we investigate the effect of nonlinear damping on the
Lugiato-Lefever equation $$ \i \partial_t a = -(\i-\zeta) a - da_{xx}
-(1+\i\kappa)|a|^2a +\i f $$ on the torus or the real line. For the case of the
torus it is shown that for small nonlinear damping $\kappa>0$ stationary
spatially periodic solutions exist on branches that bifurcate from constant
solutions whereas all nonconstant solutions disappear when the damping
parameter $\kappa$ exceeds a critical value. These results apply both for
normal ($d<0$) and anomalous ($d>0$) dispersion. For the case of the real line
we show by the Implicit Function Theorem that for small nonlinear damping
$\kappa>0$ and large detuning $\zeta\gg 1$ and large forcing $f\gg 1$ strongly
localized, bright solitary stationary solutions exists in the case of anomalous
dispersion $d>0$. These results are achieved by using techniques from
bifurcation and continuation theory and by proving a convergence result for
solutions of the time-dependent Lugiato-Lefever equation.",1811.12200v3
2018-11-26,Linear Theory of Electron-Plasma Waves at Arbitrary Collisionality,"The dynamics of electron-plasma waves are described at arbitrary
collisionality by considering the full Coulomb collision operator. The
description is based on a Hermite-Laguerre decomposition of the velocity
dependence of the electron distribution function. The damping rate, frequency,
and eigenmode spectrum of electron-plasma waves are found as functions of the
collision frequency and wavelength. A comparison is made between the
collisionless Landau damping limit, the Lenard-Bernstein and Dougherty
collision operators, and the electron-ion collision operator, finding large
deviations in the damping rates and eigenmode spectra. A purely damped entropy
mode, characteristic of a plasma where pitch-angle scattering effects are
dominant with respect to collisionless effects, is shown to emerge numerically,
and its dispersion relation is analytically derived. It is shown that such a
mode is absent when simplified collision operators are used, and that
like-particle collisions strongly influence the damping rate of the entropy
mode.",1811.12855v2
2019-05-31,The amplitude of solar p-mode oscillations from three-dimensional convection simulations,"The amplitude of solar p-mode oscillations is governed by stochastic
excitation and mode damping, both of which take place in the surface convection
zone. However, the time-dependent, turbulent nature of convection makes it
difficult to self-consistently study excitation and damping processes through
the use of traditional one-dimensional hydrostatic models. To this end, we
carried out \textit{ab initio} three-dimensional, hydrodynamical numerical
simulations of the solar atmosphere to investigate how p-modes are driven and
dissipated in the Sun. The description of surface convection in the simulations
is free from the tuneable parameters typically adopted in traditional
one-dimensional models. Mode excitation and damping rates are computed based on
analytical expressions whose ingredients are evaluated directly from the
three-dimensional model. With excitation and damping rates both available, we
estimate the theoretical oscillation amplitude and frequency of maximum power,
$\nu_{\max}$, for the Sun. We compare our numerical results with helioseismic
observations, finding encouraging agreement between the two. The numerical
method presented here provides a novel way to investigate the physical
processes responsible for mode driving and damping, and should be valid for all
solar-type oscillating stars.",1905.13397v2
2020-07-16,Linearized wave-damping structure of Vlasov-Poisson in $\mathbb R^3$,"In this paper we study the linearized Vlasov-Poisson equation for localized
disturbances of an infinite, homogeneous Maxwellian background distribution in
$\mathbb R^3_x \times \mathbb R^3_v$. In contrast with the confined case
$\mathbb T^d _x \times \mathbb R_v ^d$, or the unconfined case $\mathbb R^d_x
\times \mathbb R^d_v$ with screening, the dynamics of the disturbance are not
scattering towards free transport as $t \to \pm \infty$: we show that the
electric field decomposes into a very weakly-damped Klein-Gordon-type evolution
for long waves and a Landau-damped evolution. The Klein-Gordon-type waves
solve, to leading order, the compressible Euler-Poisson equations linearized
about a constant density state, despite the fact that our model is
collisionless, i.e. there is no trend to local or global thermalization of the
distribution function in strong topologies. We prove dispersive estimates on
the Klein-Gordon part of the dynamics. The Landau damping part of the electric
field decays faster than free transport at low frequencies and damps as in the
confined case at high frequencies; in fact, it decays at the same rate as in
the screened case. As such, neither contribution to the electric field behaves
as in the vacuum case.",2007.08580v1
2020-07-25,Using a Lindbladian approach to model decoherence in two coupled nuclear spins via correlated phase-damping and amplitude damping noise channels,"In this work, we studied the relaxation dynamics of coherences of different
order present in a system of two coupled nuclear spins. We used a previously
designed model for intrinsic noise present in such systems which considers the
Lindblad master equation for Markovian relaxation. We experimentally created
zero-, single- and double- quantum coherences in several two-spin systems and
performed a complete state tomography and computed state fidelity. We
experimentally measured the decay of zero- and double- quantum coherences in
these systems. The experimental data fitted well to a model that considers the
main noise channels to be a correlated phase damping channel acting
simultaneously on both spins in conjunction with a generalized amplitude
damping channel acting independently on both spins. The differential relaxation
of multiple-quantum coherences can be ascribed to the action of a correlated
phase damping channel acting simultaneously on both the spins.",2007.12972v1
2010-05-26,Indirect Evidence for Lévy Walks in Squeeze Film Damping,"Molecular flow gas damping of mechanical motion in confined geometries, and
its associated noise, is important in a variety of fields, including precision
measurement, gravitational wave detection, and MEMS devices. We used two
torsion balance instruments to measure the strength and distance-dependence of
`squeeze film' damping. Measured quality factors derived from free decay of
oscillation are consistent with gas particle superdiffusion in L\'evy walks and
inconsistent with those expected from traditional Gaussian random walk particle
motion. The distance-dependence of squeeze film damping observed in our
experiments is in agreement with a parameter-free Monte Carlo simulation. The
squeeze film damping of the motion of a plate suspended a distance d away from
a parallel surface scales with a fractional power between 1/d and 1/d^2.",1005.4926v2
2010-05-28,Gravitational wave asteroseismology with fast rotating neutron stars,"We investigate damping and growth times of the f-mode for rapidly rotating
stars and a variety of different polytropic equations of state in the Cowling
approximation. We discuss the differences in the eigenfunctions of co- and
counterrotating modes and compute the damping times of the f-mode for several
EoS and all rotation rates up to the Kepler-limit. This is the first study of
the damping/growth time of this type of oscillations for fast rotating neutron
stars in a general relativistic framework. We use these frequencies and
damping/growth times to create robust empirical formulae which can be used for
gravitational wave asteroseismology. The estimation of the damping/growth time
is based on the quadrupole formula and our results agree very well with
Newtonian ones in the appropriate limit.",1005.5228v3
2017-01-12,Blow-up for semilinear wave equations with the scale invariant damping and super-Fujita exponent,"The blow-up for semilinear wave equations with the scale invariant damping
has been well-studied for sub-Fujita exponent. However, for super-Fujita
exponent, there is only one blow-up result which is obtained in 2014 by
Wakasugi in the case of non-effective damping. In this paper we extend his
result in two aspects by showing that: (I) the blow-up will happen for bigger
exponent, which is closely related to the Strauss exponent, the critical number
for non-damped semilinear wave equations; (II) such a blow-up result is
established for a wider range of the constant than the known non-effective one
in the damping term.",1701.03232v3
2018-05-29,Enhancing precision of damping rate by PT symmetric Hamiltonian,"We utilize quantum Fisher information to investigate the damping parameter
precision of a dissipative qubit. PT symmetric non-Hermitian Hamiltonian is
used to enhance the parameter precision in two models: one is direct PT
symmetric quantum feedback; the other is that the damping rate is encoded into
a effective PT symmetric non-Hermitian Hamiltonian conditioned on the absence
of decay events. We find that compared with the case without feedback and with
Hermitian quantum feedback, direct PT symmetric non-Hermitan quantum feedback
can obtain better precision of damping rate. And in the second model the result
shows that the uncertainty of damping rate can be close to 0 at the exceptional
point. We also obtain that non-maximal multiparticle entanglement can improve
the precision to reach Heisenberg limit.",1805.11216v1
2001-07-19,Manifold Damping of Transverse Wakefields in High Phase Advance Traveling Wave Structures and Local Damping of Dipole Wakefields in Standing Wave Accelerators,"Operating the SLAC/KEK DDS (Damped Detuned Structure) X-band linacs at high
gradients (in excess of 70MV/m) has recently been found to be limited by the
accelerator structures breaking down and as a consequence severe damage occurs
to the cells which makes the structures inoperable. A series of recent
experiments at SLAC indicates that arcing in the structures is significantly
reduced if the group velocity of the accelerating mode is reduced and
additionally it has been discovered that reducing the length of the
accelerating structure also limits the number and intensity of breakdown events
[1]. However, in designing new accelerating structures care must be taken to
ensure that the beam-induced transverse wakefields do not cause the beam to
become unstable. Here, we report on damping transverse wakefields in two
different short structures: a 90cm traveling wave structure in which the
wakefield is coupled out to four attached manifolds and secondly, in a standing
wave structure in which a limited number of cells heavily damp down the
wakefield.
  [1] C. Adolphsen, ROAA003, this conf.",0107048v1
2012-04-11,Formation of bremsstrahlung in an absorptive QED/QCD medium,"The radiative energy loss of a relativistic charge in a dense, absorptive
medium can be affected significantly by damping phenomena. The effect is more
pronounced for large energies of the charge and/or large damping of the
radiation. This can be understood in terms of a competition between the
formation time of bremsstrahlung and a damping time scale. We discuss this
competition in detail for the absorptive QED and QCD medium, focusing on the
case in which the mass of the charge is large compared to the in-medium mass of
the radiation quanta. We identify the regions in energy and parameter space, in
which either coherence or damping effects are of major importance for the
radiative energy loss spectrum. We show that damping phenomena can lead to a
stronger suppression of the spectrum than coherence effects.",1204.2469v2
2014-05-09,Magnetization dynamics and damping due to electron-phonon scattering in a ferrimagnetic exchange model,"We present a microscopic calculation of magnetization damping for a magnetic
""toy model."" The magnetic system consists of itinerant carriers coupled
antiferromagnetically to a dispersionless band of localized spins, and the
magnetization damping is due to coupling of the itinerant carriers to a phonon
bath in the presence of spin-orbit coupling. Using a mean-field approximation
for the kinetic exchange model and assuming the spin-orbit coupling to be of
the Rashba form, we derive Boltzmann scattering integrals for the distributions
and spin coherences in the case of an antiferromagnetic exchange splitting,
including a careful analysis of the connection between lifetime broadening and
the magnetic gap. For the Elliott-Yafet type itinerant spin dynamics we extract
dephasing and magnetization times T_1 and T_2 from initial conditions
corresponding to a tilt of the magnetization vector, and draw a comparison to
phenomenological equations such as the Landau-Lifshitz or the Gilbert damping.
We also analyze magnetization precession and damping for this system including
an anisotropy field and find a carrier mediated dephasing of the localized spin
via the mean-field coupling.",1405.2347v1
2014-05-16,Quantum corrections to nonlinear ion acoustic wave with Landau damping,"Quantum corrections to nonlinear ion acoustic wave with Landau damping have
been computed using Wigner equation approach. The dynamical equation governing
the time development of nonlinear ion acoustic wave with semiclassical quantum
corrections is shown to have the form of higher KdV equation which has higher
order nonlinear terms coming from quantum corrections, with the usual classical
and quantum corrected Landau damping integral terms.
  The conservation of total number of ions is shown from the evolution
equation. The decay rate of KdV solitary wave amplitude due to presence of
Landau damping terms has been calculated assuming the Landau damping parameter
$\alpha_1 = \sqrt{{m_e}/{m_i}}$ to be of the same order of the quantum
parameter $Q = {\hbar^2}/({24 m^2 c^2_{s} L^2})$. The amplitude is shown to
decay very slowly with time as determined by the quantum factor $ Q$.",1405.4107v1
2014-05-19,Mesh Size and Damped Edge Effects in Micromagnetic Spin Wave Simulation,"We have studied the dependence of spin wave dispersion on the characteristics
of the mesh used in a finite element micromagnetic simulation. It is shown that
the dispersion curve has a cut off at a frequency which is analytically
predictable. The frequency depends on the average mesh length used for the
simulation. Based on this, a recipe to effectively obtain the dispersion
relation has been suggested. In a separate study, spin wave reflections are
absorbed by introducing highly damped edges in the device. However, an abrupt
change in the damping parameter causes reflections. We compare damping profiles
and identify an exponential damping profile as causing significantly less
reflections.",1405.4615v2
2017-12-05,Dark Matter Annihilation from Nearby Ultra-compact Micro Halos to Explain the Tentative Excess at ~1.4 TeV in DAMPE data,"The tentative 1.4 TeV excess in the $e^+e^-$ spectrum measured by The DArk
Matter Particle Explorer (DAMPE) motivates the possible existence of one or
more local dark matter concentrated regions. In particular, Ultra-compact Micro
Halos (UCMHs) seeded by large density perturbations in the early universe,
allocated within ~0.3 kpc from the solar system, could provide the potential
source of electrons and positrons produced from dark matter annihilation,
enough to explain the DAMPE signal. Here we consider a UCMH with density
profile assuming radial in-fall and explore the preferred halo parameters to
explain the 1.4 TeV ""DAMPE excess"". We find that typical parameter space of
UCMHs can easily explain the ""DAMPE excess"" with usual thermal-averaged
annihilation cross section of WIMP. The fraction of dark matter stored in such
UCMHs in the Galactic-scale halo can be reduced to as small as $O(10^{-5})$,
well within the current cosmological and astrophysical constraints.",1712.01724v2
2017-12-21,A new charge reconstruction algorithm for the DAMPE silicon microstrip detector,"The DArk Matter Particle Explorer (DAMPE) is one of the four satellites
within the Strategic Pioneer Research Program in Space Science of the Chinese
Academy of Science (CAS). The Silicon-Tungsten Tracker (STK), which is composed
of 768 singled-sided silicon microstrip detectors, is one of the four
subdetectors in DAMPE, providing track reconstruction and charge identification
for relativistic charged particles. The charge response of DAMPE silicon
microstrip detectors is complicated, depending on the incident angle and impact
position. A new charge reconstruction algorithm for the DAMPE silicon
microstrip detector is introduced in this paper. This algorithm can correct the
complicated charge response, and was proved applicable by the ion test beam.",1712.08011v1
2018-01-23,The dominancy of damping like torque for the current induced magnetization switching in Pt/Co/W multilayers,"Two classes of spin-orbit coupling (SOC) mechanisms have been considered as
candidate sources for the spin orbit torque (SOT): the spin Hall Effect (SHE)
in heavy metals with strong SOC and the Rashba effect arising from broken
inversion symmetry at material surfaces and interfaces. In this work, we have
investigated the SOT in perpendicularly magnetized Pt/Co/W films, which is
compared with the results in Pt/Co/AlOx films. Theoretically, in the case of
the asymmetric structure of trilayers with opposite sign of spin Hall angle,
both damping like torque and field like torque due to the SHE and the Rashba
effect will be enhanced. Using the harmonic measurements, we have characterized
the effective fields corresponding to the damping like torque and the field
like torque, but we have found the dominancy of damping like torque in the
Pt/Co/W films. It is much different from the results in the Pt/Co/AlOx films,
in which both the damping like torque and the field like torque are strong.",1801.07408v1
2019-10-03,Many-body collision contributions to electron momentum damping rates in a plasma influenced by electron strong coupling,"Experimental studies of electron-ion collision rates in an ultracold neutral
plasma (UNP) can be conducted through measuring the rate of electron plasma
oscillation damping. For sufficiently cold and dense conditions where strong
coupling influences are important, the measured damping rate was faster by 37\%
than theoretical expectations [W. Chen, C. Witte, and J. Roberts, Phys. Rev. E
\textbf{96}, 013203 (2017)]. We have conducted a series of numerical
simulations to isolate the primary source of this difference. By analyzing the
distribution of electron velocity changes due to collisions in a molecular
dynamics simulation, examining the trajectory of electrons with high deflection
angle in such simulations, and examining the oscillation damping rate while
varying the ratio of two-body to three-body electron-ion collision rates, we
have found that the difference is consistent with the effect due to many-body
collisions leading to bound electrons. This has implications for other
electron-ion collision related transport properties in addition to electron
oscillation damping.",1910.01707v1
2019-10-18,Escape of a forced-damped particle from weakly nonlinear truncated potential well,"Escape from a potential well is an extreme example of transient behavior. We
consider the escape of the harmonically forced particle under viscous damping
from the benchmark truncated weakly nonlinear potential well. Main attention is
paid to most interesting case of primary 1:1 resonance. The treatment is based
on multiple-scales analysis and exploration of the slow-flow dynamics. Contrary
to Hamiltonian case described in earlier works, in the case with damping the
slow-flow equations are not integrable. However, if the damping is small
enough, it is possible to analyze the perturbed slow-flow equations. The effect
of the damping on the escape threshold is evaluated in the explicit analytic
form. Somewhat unexpectedly, the escape mechanisms in terms of the slow flow
are substantially different for the linear and weakly nonlinear cases.",1910.08545v1
2019-10-24,Topological damping Rashba spin orbit torque in ballistic magnetic domain walls,"Rashba spin orbit torque derived from the broken inversion symmetry at
ferromagnet/heavy metal interfaces has potential application in spintronic
devices. In conventional description of the precessional and damping components
of the Rashba spin orbit torque in magnetization textures, the decomposition
coefficients are assumed to be independent of the topology of the underlying
structure. Contrary to this common wisdom, for Schr\""{o}dinger electrons
trespassing ballistically across a magnetic domain wall, we found that the
decomposition coefficient of the damping component is determined by the
topology of the domain wall. The resultant damping Rashba spin orbit torque is
protected by the topology of the underlying magnetic domain wall and robust
against small deviations from the ideal domain wall profile. Our identification
of a topological damping Rashba spin orbit torque component in magnetic domain
walls will help to understand experiments on current driven domain wall motion
in ferromagnet/heavy metal systems with broken inversion symmetry and to
facilitate its utilization in innovative device designs.",1910.10977v2
2020-02-07,Model of damping and anisotropy at elevated temperatures: application to granular FePt films,"Understanding the damping mechanism in finite size systems and its dependence
on temperature is a critical step in the development of magnetic
nanotechnologies. In this work, nano-sized materials are modeled via atomistic
spin dynamics, the damping parameter being extracted from Ferromagnetic
Resonance (FMR) simulations applied for FePt systems, generally used for
heat-assisted magnetic recording media (HAMR). We find that the damping
increases rapidly close to Tc and the effect is enhanced with decreasing system
size, which is ascribed to scattering at the grain boundaries. Additionally,
FMR methods provide the temperature dependence of both damping and the
anisotropy, important for the development of HAMR. Semi-analytical calculations
show that, in the presence of a grain size distribution, the FMR linewidth can
decrease close to the Curie temperature due to a loss of inhomogeneous line
broadening. Although FePt has been used in this study, the results presented in
the current work are general and valid for any ferromagnetic material.",2002.02865v1
2020-04-06,Damping-like Torque in Monolayer 1T-TaS$_2$,"A damping-like spin orbit torque (SOT) is a prerequisite for ultralow power
spin logic devices. Here, we report on the damping-like SOT in just one
monolayer of the conducting transition metal dichalcogenide (TMD) TaS$_2$
interfaced with a NiFe (Py) ferromagnetic layer. The charge-spin conversion
efficiency is found to be 0.25$\pm$0.03 and the spin Hall conductivity (2.63
$\times$ 10$^5$ $\frac{\hbar}{2e}$ $\Omega^{-1}$ m$^{-1}$) is found to be
superior to values reported for other TMDs. The origin of this large
damping-like SOT can be found in the interfacial properties of the TaS$_2$/Py
heterostructure, and the experimental findings are complemented by the results
from density functional theory calculations. The dominance of damping-like
torque demonstrated in our study provides a promising path for designing next
generation conducting TMD based low-powered quantum memory devices.",2004.02649v1
2021-01-03,The effect of flow on resonant absorption of slow MHD waves in magnetic flux tubes,"In this paper, we study kink and sausage oscillations in the presence of
longitudinal background flow. We study resonant absorption of the kink and
sausage modes in the slow continuum under magnetic pore conditions in the
presence of flow. we determine the dispersion relation then solve it
numerically, and find the frequencies and damping rates of the slow kink and
sausage surface modes. We also, obtain analytical solution for the damping rate
of the slow surface mode in the long wavelength limit. We show that in the
presence of plasma flow, resonance absorption can result in strong damping for
forward waves and can be considered as an efficient mechanism to justify the
extremely rapid damping of slow surface sausage waves observed in magnetic
pores. Also, the plasma flow reduces the efficiency of resonance absorption to
damp backward waves. Furthermore, for the pore conditions, the resonance
instability is avoided in our model.",2101.02064v1
2017-05-21,Dynamical depinning of chiral domain walls,"The domain wall depinning field represents the minimum magnetic field needed
to move a domain wall, typically pinned by samples' disorder or patterned
constrictions. Conventionally, such field is considered independent on the
Gilbert damping since it is assumed to be the field at which the Zeeman energy
equals the pinning energy barrier (both damping independent). Here, we analyse
numerically the domain wall depinning field as function of the Gilbert damping
in a system with perpendicular magnetic anisotropy and Dzyaloshinskii-Moriya
interaction. Contrary to expectations, we find that the depinning field depends
on the Gilbert damping and that it strongly decreases for small damping
parameters. We explain this dependence with a simple one-dimensional model and
we show that the reduction of the depinning field is related to the internal
domain wall dynamics, proportional to the Dzyaloshinskii-Moriya interaction,
and the finite size of the pinning barriers.",1705.07489v2
2017-09-27,Wave turbulence in vibrating plates : the effect of damping,"The effect of damping in the wave turbulence regime for thin vibrating plates
is studied. An experimental method, allowing measurements of dissipation in the
system at all scales, is first introduced. Practical experimental devices for
increasing the dissipation are used. The main observable consequence of
increasing the damping is a significant modification in the slope of the power
spectral density, so that the observed power laws are not in a pure inertial
regime. However, the system still displays a turbulent behavior with a cut-off
frequency that is determined by the injected power which does not depend on
damping. By using the measured damping power-law in numerical simulations,
similar conclusions are drawn out.",1709.09438v1
2017-11-02,Vibration Damping of Carbon Nanotube Assembly Materials,"Vibration reduction is of great importance in various engineering
applications, and a material that exhibits good vibration damping along with
high strength and modulus has become more and more vital. Owing to the superior
mechanical property of carbon nanotube (CNT), new types of vibration damping
material can be developed. This paper presents recent advancements, including
our progresses, in the development of high-damping macroscopic CNT assembly
materials, such as forests, gels, films, and fibers. In these assemblies,
structural deformation of CNTs, zipping and unzipping at CNT connection nodes,
strengthening and welding of the nodes, and sliding between CNTs or CNT bundles
are playing important roles in determining the viscoelasticity, and elasticity
as well. Towards the damping enhancement, strategies for micro-structure and
interface design are also discussed.",1711.00623v1
2018-05-31,Damping Effect on PageRank Distribution,"This work extends the personalized PageRank model invented by Brin and Page
to a family of PageRank models with various damping schemes. The goal with
increased model variety is to capture or recognize a larger number of types of
network activities, phenomena and propagation patterns. The response in
PageRank distribution to variation in damping mechanism is then characterized
analytically, and further estimated quantitatively on 6 large real-world link
graphs. The study leads to new observation and empirical findings. It is found
that the difference in the pattern of PageRank vector responding to parameter
variation by each model among the 6 graphs is relatively smaller than the
difference among 3 particular models used in the study on each of the graphs.
This suggests the utility of model variety for differentiating network
activities and propagation patterns. The quantitative analysis of the damping
mechanisms over multiple damping models and parameters is facilitated by a
highly efficient algorithm, which calculates all PageRank vectors at once via a
commonly shared, spectrally invariant subspace. The spectral space is found to
be of low dimension for each of the real-world graphs.",1806.00127v1
2018-07-13,Gilbert damping of high anisotropy Co/Pt multilayers,"Using broadband ferromagnetic resonance, we measure the damping parameter of
[Co(5 \r{A})/Pt(3 \r{A})]${\times 6}$ multilayers whose growth was optimized to
maximize the perpendicular anisotropy. Structural characterizations indicate
abrupt interfaces essentially free of intermixing despite the miscible
character of Co and Pt. Gilbert damping parameters as low as 0.021 can be
obtained despite a magneto-crystalline anisotropy as large as
$10^6~\textrm{J/m}^3$. The inhomogeneous broadening accounts for part of the
ferromagnetic resonance linewidth, indicating some structural disorder leading
to a equivalent 20 mT of inhomogenity of the effective field. The unexpectedly
relatively low damping factor indicates that the presence of the Pt heavy metal
within the multilayer may not be detrimental to the damping provided that
intermixing is avoided at the Co/Pt interfaces.",1807.04977v1
2018-08-10,Relativistic charge solitons created due to nonlinear Landau damping: A candidate for explaining coherent radio emission in pulsars,"A potential resolution for the generation of coherent radio emission in
pulsar plasma is the existence of relativistic charge solitons, which are
solutions of nonlinear Schr\""{o}dinger equation (NLSE). In an earlier study,
Melikidze et al. (2000) investigated the nature of these charge solitons;
however, their analysis ignored the effect of nonlinear Landau damping, which
is inherent in the derivation of the NLSE in the pulsar pair plasma. In this
paper we include the effect of nonlinear Landau damping and obtain solutions of
the NLSE by applying a suitable numerical scheme. We find that for reasonable
parameters of the cubic nonlinearity and nonlinear Landau damping, soliton-like
intense pulses emerge from an initial disordered state of Langmuir waves and
subsequently propagate stably over sufficiently long times, during which they
are capable of exciting the coherent curvature radiation in pulsars. We
emphasize that this emergence of {\em stable} intense solitons from a
disordered state does not occur in a purely cubic NLSE; thus, it is {\em
caused} by the nonlinear Landau damping.",1808.03657v1
2018-08-13,Gilbert damping phenomenology for two-sublattice magnets,"We present a systematic phenomenological description of Gilbert damping in
two-sublattice magnets. Our theory covers the full range of materials from
ferro- via ferri- to antiferromagnets. Following a Rayleigh dissipation
functional approach within a Lagrangian classical field formulation, the theory
captures intra- as well as cross-sublattice terms in the Gilbert damping,
parameterized by a 2$\times$2 matrix. When spin-pumping into an adjacent
conductor causes dissipation, we obtain the corresponding Gilbert damping
matrix in terms of the interfacial spin-mixing conductances. Our model
reproduces the experimentally observed enhancement of the ferromagnetic
resonance linewidth in a ferrimagnet close to its compensation temperature
without requiring an increased Gilbert parameter. It also predicts new
contributions to damping in an antiferromagnet and suggests the resonance
linewidths as a direct probe of the sublattice asymmetry, which may stem from
boundary or bulk.",1808.04385v2
2019-01-07,Giant anisotropy of Gilbert damping in epitaxial CoFe films,"Tailoring Gilbert damping of metallic ferromagnetic thin films is one of the
central interests in spintronics applications. Here we report a giant Gilbert
damping anisotropy in epitaxial Co$_{50}$Fe$_{50}$ thin film with a
maximum-minimum damping ratio of 400 \%, determined by broadband spin-torque as
well as inductive ferromagnetic resonance. We conclude that the origin of this
damping anisotropy is the variation of the spin orbit coupling for different
magnetization orientations in the cubic lattice, which is further corroborate
from the magnitude of the anisotropic magnetoresistance in Co$_{50}$Fe$_{50}$.",1901.01941v1
2019-01-17,"Influences of interfacial oxidization on surface magnetic energy, magnetic damping and spin-orbit-torques in Pt / ferromagnet / capping structures","We investigate the effect of capping layer (CAP) on the interfacial magnetic
anisotropy energy density (K_S), magnetic damping ({\alpha}), and spin-orbit
torques (SOTs) in heavy-metal (Pt) / ferromagnet (Co or Py) / CAP (MgO/Ta,
HfOx, or TaN). At room temperature (RT) the CAP materials influence the
effective magnitude of K_S, which is associated with a formation of interfacial
magnetic oxides. The dynamical dissipation parameters of Co are considerably
influenced by the CAP (especially MgO) while those of Py are not. This is
possibly due to an extra magnetic damping via spin-pumping process across the
Co/CoO interface and incoherent magnon generation (spin fluctuation) in the
interfacial CoO. It is also observed that both anti-damping and field-like SOT
efficiencies vary marginally with the CAP in the thickness ranges we examined.
Our results reveal the crucial role of interfacial oxides on the perpendicular
magnetic anisotropy, magnetic damping, and SOTs.",1901.05777v1
2019-08-23,Damping enhancement in coherent ferrite/insulating-paramagnet bilayers,"High-quality epitaxial ferrites, such as low-damping MgAl-ferrite (MAFO), are
promising nanoscale building blocks for all-oxide heterostructures driven by
pure spin current. However, the impact of oxide interfaces on spin dynamics in
such heterostructures remains an open question. Here, we investigate the spin
dynamics and chemical and magnetic depth profiles of 15-nm-thick MAFO
coherently interfaced with an isostructural $\approx$1-8-nm-thick overlayer of
paramagnetic CoCr$_2$O$_4$ (CCO) as an all-oxide model system. Compared to MAFO
without an overlayer, effective Gilbert damping in MAFO/CCO is enhanced by a
factor of $>$3, irrespective of the CCO overlayer thickness. We attribute this
damping enhancement to spin scattering at the $\sim$1-nm-thick chemically
disordered layer at the MAFO/CCO interface, rather than spin pumping or
proximity-induced magnetism. Our results indicate that damping in ferrite-based
heterostructures is strongly influenced by interfacial chemical disorder, even
if the thickness of the disordered layer is a small fraction of the ferrite
thickness.",1908.08629v2
2019-11-02,Tuning Non-Gilbert-type damping in FeGa films on MgO(001) via oblique deposition,"The ability to tailor the damping factor is essential for spintronic and
spin-torque applications. Here, we report an approach to manipulate the damping
factor of FeGa/MgO(001) films by oblique deposition. Owing to the defects at
the surface or interface in thin films, two-magnon scattering (TMS) acts as a
non-Gilbert damping mechanism in magnetization relaxation. In this work, the
contribution of TMS was characterized by in-plane angular dependent
ferromagnetic resonance (FMR). It is demonstrated that the intrinsic Gilbert
damping is isotropic and invariant, while the extrinsic mechanism related to
TMS is anisotropic and can be tuned by oblique deposition. Furthermore, the two
and fourfold TMS related to the uniaxial magnetic anisotropy (UMA) and
magnetocrystalline anisotropy were discussed. Our results open an avenue to
manipulate magnetization relaxation in spintronic devices.",1911.00728v1
2019-11-13,Dipole oscillations of fermionic superfluids along the BEC-BCS crossover in disordered potentials,"We investigate dipole oscillations of ultracold Fermi gases along the BEC-BCS
crossover through disordered potentials. We observe a disorder-induced damping
of oscillations as well as a change of the fundamental Kohn-mode frequency. The
measurement results are compared to numerical density matrix renormalization
group calculations as well as to a three-dimensional simulation of
non-interacting fermions. Experimentally, we find a disorder-dependent damping,
which grows approximately with the second power of the disorder strength.
Moreover, we observe experimentally a change of oscillation frequency which
deviates from the expected behavior of a damped harmonic oscillator on a
percent level. While this behavior is qualitatively expected from the
theoretical models used, quantitatively the experimental observations show a
significantly stronger effect than predicted by theory. Furthermore, while the
frequency shift seems to scale differently with interaction strength in the BEC
versus BCS regime, the damping coefficient apparently decreases with the
strength of interaction, but not with the sign, which changes for BEC and BCS
type Fermi gases. This is surprising, as the dominant damping mechanisms are
expected to be different in the two regimes.",1911.05638v1
2020-05-15,Calibration and performance of the neutron detector onboard of the DAMPE mission,"The DArk Matter Particle Explorer (DAMPE), one of the four space-based
scientific missions within the framework of the Strategic Pioneer Program on
Space Science of the Chinese Academy of Sciences, has been successfully
launched on Dec. 17th 2015 from Jiuquan launch center. One of the most
important scientific goals of DAMPE is to search for the evidence of dark
matter indirectly by measuring the spectrum of high energy cosmic-ray
electrons. The neutron detector, one of the four sub-payloads of DAMPE, is
designed to distinguish high energy electrons from hadron background by
measuring the secondary neutrons produced in the shower. In this paper, a
comprehensive introduction of the neutron detector is presented, including the
design, the calibration and the performance. The analysis with simulated data
and flight data indicates a powerful proton rejection capability of the neutron
detector, which plays an essential role for TeV electron identification of
DAMPE.",2005.07828v1
2020-05-16,Simultaneous observation of anti-damping and inverse spin Hall effect in La$_{0.67}$Sr$_{0.33}$MnO$_{3}$/Pt bilayer system,"Manganites have shown potential in spintronics because they exhibit high spin
polarization. Here, by ferromagnetic resonance we have studied the damping
properties of La$_{0.67}$Sr$_{0.33}$MnO$_{3}$/Pt bilayers which are prepared by
oxide molecular beam epitaxy. The damping coefficient ($\alpha$) of
La$_{0.67}$Sr$_{0.33}$MnO$_{3}$ (LSMO) single layer is found to be 0.0104.
However the LSMO/Pt bilayers exhibit decrease in $\alpha$ with increase in Pt
thickness. This decrease in the value of $\alpha$ is probably due to high
anti-damping like torque. Further, we have investigated the angle dependent
inverse spin Hall effect (ISHE) to quantify the spin pumping voltage from other
spin rectification effects such as anomalous Hall effect and anisotropic
magnetoresistance. We have observed high spin pumping voltage ($\sim$~20 $ \mu
V$). The results indicate that both anti-damping and spin pumping phenomena are
occuring simultaneously.",2005.07848v3
2020-09-29,The effects of nonlinear damping on degenerate parametric amplification,"This paper considers the dynamic response of a single degree of freedom
system with nonlinear stiffness and nonlinear damping that is subjected to both
resonant direct excitation and resonant parametric excitation, with a general
phase between the two. This generalizes and expands on previous studies of
nonlinear effects on parametric amplification, notably by including the effects
of nonlinear damping, which is commonly observed in a large variety of systems,
including micro- and nano-scale resonators. Using the method of averaging, a
thorough parameter study is carried out that describes the effects of the
amplitudes and relative phase of the two forms of excitation. The effects of
nonlinear damping on the parametric gain are first derived. The transitions
among various topological forms of the frequency response curves, which can
include isolae, dual peaks, and loops, are determined, and bifurcation analyses
in parameter spaces of interest are carried out. In general, these results
provide a complete picture of the system response and allow one to select drive
conditions of interest that avoid bistability while providing maximum amplitude
gain, maximum phase sensitivity, or a flat resonant peak, in systems with
nonlinear damping.",2009.14284v2
2020-11-10,Damped oscillators within the general theory of Casimir and van der Waals forces,"It is demonstrated that the general theory of Casimir and van der Waals
forces describes the interaction-induced equilibrium thermodynamic potentials
of the damped harmonic oscillator bilinearly coupled to the environment. An
extended model for a damped oscillator is suggested along the lines of the
general theory of Casimir and van der Waals forces, and the corresponding
thermodynamic quantities obtained. While the original model involves a heat
bath consisting of a large number of free oscillators having infinitesimal
damping functions, the extended model allows any generally admissible frequency
and temperature dependent dissipative susceptibilities of the heat bath
constituents, influenced by the additional dissipative environmental channels
that are not directly linked to the system oscillator. Consequently, the
results obtained are applicable to the frequency and temperature dependent
damping function of the system oscillator.",2011.04960v2
2020-11-16,Technology to Counter Online Flaming Based on the Frequency-Dependent Damping Coefficient in the Oscillation Model,"Online social networks, which are remarkably active, often experience
explosive user dynamics such as online flaming, which can significantly impact
the real world. However, countermeasures based on social analyses of the
individuals causing flaming are too slow to be effective because of the
rapidity with which the influence of online user dynamics propagates. A
countermeasure technology for the flaming phenomena based on the oscillation
model, which describes online user dynamics, has been proposed; it is an
immediate solution as it does not depend on social analyses of individuals.
Conventional countermeasures based on the oscillation model assume that the
damping coefficient is a constant regardless of the eigenfrequency. This
assumption is, however, problematic as the damping coefficients are, in
general, inherently frequency-dependent; the theory underlying the dependence
is being elucidated. This paper discusses a design method that uses the damping
coefficient to prevent flaming under general conditions considering the
frequency-dependence of the damping coefficient and proposes a countermeasure
technology for the flaming phenomena.",2011.08117v1
2021-02-01,Blow-up and lifespan estimates for a damped wave equation in the Einstein-de Sitter spacetime with nonlinearity of derivative type,"In this article, we investigate the blow-up for local solutions to a
semilinear wave equation in the generalized Einstein - de Sitter spacetime with
nonlinearity of derivative type. More precisely, we consider a semilinear
damped wave equation with a time-dependent and not summable speed of
propagation and with a time-dependent coefficient for the linear damping term
with critical decay rate. We prove in this work that the results obtained in a
previous work, where the damping coefficient takes two particular values $0$ or
$2$, can be extended for any positive damping coefficient. In the blow-up case,
the upper bound of the exponent of the nonlinear term is given, and the
lifespan estimate of the global existence time is derived as well.",2102.01137v2
2021-02-02,Analysis of Lower Hybrid Drift Waves in Kappa Distributions over Solar Atmosphere,"Kappa distributions and with loss cone features have been frequently observed
with flares emissions with the signatures of Lower hybrid waves. We have
analysed the plasma with Kappa distributions and with loss cone features for
the drift wave instabilities in perpendicular propagation for Large flare and
Normal flare and Coronal condition . While analysing the growth/damping rate,
we understand that the growth of propagation of EM waves increases with kappa
distribution index for all the three cases. In comparing the propagation large
flare shows lesser growth in compared with the normal and the coronal plasmas.
When added the loss cone features to Kappa distributions, we find that the
damping of EM wave propagation takes place. The damping rate EM waves is
increases with perpendicular temperature and loss cone index l, in all the
three cases but damping is very high for large flare and then normal in
comparision with coronal condition. This shows that the lower hybrid damping
may be the source of coronal heating.",2102.01323v1
2021-02-25,Regularity and stability of the semigroup associated with some interacting elastic systems I: A degenerate damping case,"In this paper, we examine regularity and stability issues for two damped
abstract elastic systems. The damping involves the average velocity and a
fractional power $\theta$, with $\theta$ in $[-1,1]$, of the principal
operator. The matrix operator defining the damping mechanism for the coupled
system is degenerate. First, we prove that for $\theta$ in $(1/2,1]$, the
underlying semigroup is not analytic, but is differentiable for $\theta$ in
$(0,1)$; this is in sharp contrast with known results for a single similarly
damped elastic system, where the semigroup is analytic for $\theta$ in
$[1/2,1]$; this shows that the degeneracy dominates the dynamics of the
interacting systems, preventing analyticity in that range. Next, we show that
for $\theta$ in $(0,1/2]$, the semigroup is of certain Gevrey classes. Finally,
we show that the semigroup decays exponentially for $\theta$ in $[0,1]$, and
polynomially for $\theta$ in $[-1,0)$. To prove our results, we use the
frequency domain method, which relies on resolvent estimates. Optimality of our
resolvent estimates is also established. Several examples of application are
provided.",2102.13217v4
2021-03-05,Existence and congruence of global attractors for damped and forced integrable and nonintegrable discrete nonlinear Schrödinger equations,"We study two damped and forced discrete nonlinear Schr\""odinger equations on
the one-dimensional infinite lattice. Without damping and forcing they are
represented by the integrable Ablowitz-Ladik equation (AL) featuring non-local
cubic nonlinear terms, and its standard (nonintegrable) counterpart with local
cubic nonlinear terms (DNLS). The global existence of a unique solution to the
initial value problem for both, the damped and forced AL and DNLS, is proven.
It is further shown that for sufficiently close initial data, their
corresponding solutions stay close for all times. Concerning the asymptotic
behaviour of the solutions to the damped and forced AL and DNLS, for the former
a sufficient condition for the existence of a restricted global attractor is
established while it is shown that the latter possesses a global attractor.
Finally, we prove the congruence of the restricted global AL attractor and the
DNLS attractor for dynamics ensuing from initial data contained in an
appropriate bounded subset in a Banach space.",2103.03533v1
2021-05-08,A second-order numerical method for Landau-Lifshitz-Gilbert equation with large damping parameters,"A second order accurate numerical scheme is proposed and implemented for the
Landau-Lifshitz-Gilbert equation, which models magnetization dynamics in
ferromagnetic materials, with large damping parameters. The main advantages of
this method are associated with the following features: (1) It only solves
linear systems of equations with constant coefficients where fast solvers are
available, so that the numerical efficiency has been greatly improved, in
comparison with the existing Gauss-Seidel project method. (2) The second-order
accuracy in time is achieved, and it is unconditionally stable for large
damping parameters. Moreover, both the second-order accuracy and the great
efficiency improvement will be verified by several numerical examples in the 1D
and 3D simulations. In the presence of large damping parameters, it is observed
that this method is unconditionally stable and finds physically reasonable
structures while many existing methods have failed. For the domain wall
dynamics, the linear dependence of wall velocity with respect to the damping
parameter and the external magnetic field will be obtained through the reported
simulations.",2105.03576v1
2021-05-17,Dissipation of Oscillation Energy and Distribution of Damping Power in a Multimachine Power System: A Small-signal Analysis,"This paper revisits the concept of damping torque in a multimachine power
system and its relation to the dissipation of oscillation energy in synchronous
machine windings. As a multimachine extension of an existing result on a
single-machine-infinite-bus (SMIB) system, we show that the total damping power
for a mode stemming from the interaction of electromagnetic torques and rotor
speeds is equal to the sum of average power dissipations in the generator
windings corresponding to the modal oscillation. Further, counter-intuitive to
the SMIB result, we demonstrate that, although the equality holds on an
aggregate, such is not the case for individual machines in an interconnected
system. To that end, distribution factors are derived for expressing the
average damping power of each generator as a linear combination of average
powers of modal energy dissipation in the windings of all machines in the
system. These factors represent the distribution of damping power in a
multimachine system. The results are validated on IEEE 4-machine and 16-machine
test systems.",2105.07618v2
2021-06-04,Imaging spin-wave damping underneath metals using electron spins in diamond,"Spin waves in magnetic insulators are low-damping signal carriers that could
enable a new generation of spintronic devices. The excitation, control, and
detection of spin waves by metal electrodes is crucial for interfacing these
devices to electrical circuits. It is therefore important to understand
metal-induced damping of spin-wave transport, but characterizing this process
requires access to the underlying magnetic films. Here we show that spins in
diamond enable imaging of spin waves that propagate underneath metals in
magnetic insulators, and then use this capability to reveal a 100-fold increase
in spin-wave damping. By analyzing spin-wave-induced currents in the metal, we
derive an effective damping parameter that matches these observations well. We
furthermore detect buried scattering centers, highlighting the technique's
power for assessing spintronic device quality. Our results open new avenues for
studying metal - spin-wave interaction and provide access to interfacial
processes such as spin-wave injection via the spin-Hall effect.",2106.02508v2
2021-06-04,Inherent Non-Linear Damping in Resonators with Inertia Amplification,"Inertia amplification is a mechanism coupling degrees of freedom within a
vibrating structure. Its goal is to achieve an apparent high dynamic mass and,
accordingly, a low resonance frequency. Such structures have been described for
use in locally resonant metamaterials and phononic crystals to lower the
starting frequency of a band gap without adding mass to the system. This study
shows that any non-linear kinematic coupling between translational or
rotational vibrations leads to the appearance of amplitude-dependent damping.
The analytical derivation of the equation of motion of a resonator with inertia
amplification creates insight in the damping process, and shows that the
vibration damping increases with its amplitude. The theoretical study is
validated by experimental evidence from two types of inertia-amplification
resonators. Finally, the importance of amplitude-dependent damping is
illustrated when the structure is used as a tuned mass damper for a cantilever
beam.",2106.02576v2
2021-06-30,On the effect of perturbations in first-order optimization methods with inertia and Hessian driven damping,"Second-order continuous-time dissipative dynamical systems with viscous and
Hessian driven damping have inspired effective first-order algorithms for
solving convex optimization problems. While preserving the fast convergence
properties of the Nesterov-type acceleration, the Hessian driven damping makes
it possible to significantly attenuate the oscillations. To study the stability
of these algorithms with respect to perturbations, we analyze the behaviour of
the corresponding continuous systems when the gradient computation is subject
to exogenous additive errors. We provide a quantitative analysis of the
asymptotic behaviour of two types of systems, those with implicit and explicit
Hessian driven damping. We consider convex, strongly convex, and non-smooth
objective functions defined on a real Hilbert space and show that, depending on
the formulation, different integrability conditions on the perturbations are
sufficient to maintain the convergence rates of the systems. We highlight the
differences between the implicit and explicit Hessian damping, and in
particular point out that the assumptions on the objective and perturbations
needed in the implicit case are more stringent than in the explicit case.",2106.16159v2
2021-07-02,Anomalous Gilbert Damping and Duffing Features of the SFS {\boldmath $\varphi_0$} Josephson Junction,"We demonstrate unusual features of phase dynamics, IV-characteristics and
magnetization dynamics of the $\varphi_0$ Josephson junction at small values of
spin-orbit interaction, ratio of Josephson to magnetic energy and Gilbert
damping. In particular, an anomalous shift of the ferromagnetic resonance
frequency with an increase of Gilbert damping is found. The ferromagnetic
resonance curves show the Duffing oscillator behaviour, reflecting the
nonlinear nature of Landau-Lifshitz-Gilbert (LLG) equation. Based on the
numerical analysis of each term in LLG equation we obtained an approximated
equation demonstrated both damping effect and Duffing oscillator features. The
resulting Duffing equation incorporates the Gilbert damping in a special way
across the dissipative term and the restoring force. A resonance method for the
determination of spin-orbit interaction in noncentrosymmetric materials which
play the role of barrier in $\varphi_0$ junctions is proposed.",2107.00982v3
2021-07-13,A new approach to the quantization of the damped harmonic oscillator,"In this paper, a new approach for constructing Lagrangians for driven and
undriven linearly damped systems is proposed, by introducing a redefined time
coordinate and an associated coordinate transformation to ensure that the
resulting Lagrangian satisfies the Helmholtz conditions. The approach is
applied to canonically quantize the damped harmonic oscillator and although it
predicts an energy spectrum that decays at the same rate to previous models,
unlike those approaches it recovers the classical critical damping condition,
which determines transitions between energy eigenstates, and is therefore
consistent with the correspondence principle. It is also demonstrated how to
apply the procedure to a driven damped harmonic oscillator.",2107.05827v3
2021-10-26,Theory of sound attenuation in amorphous solids from nonaffine motions,"We present a theoretical derivation of acoustic phonon damping in amorphous
solids based on the nonaffine response formalism for the viscoelasticity of
amorphous solids. The analytical theory takes into account the nonaffine
displacements in transverse waves and is able to predict both the ubiquitous
low-energy diffusive damping $\sim k^{2}$, as well as a novel contribution to
the Rayleigh damping $\sim k^{4}$ at higher wavevectors and the crossover
between the two regimes observed experimentally. The coefficient of the
diffusive term is proportional to the microscopic viscous (Langevin-type)
damping in particle motion (which arises from anharmonicity), and to the
nonaffine correction to the static shear modulus, whereas the Rayleigh damping
emerges in the limit of low anharmonicity, consistent with previous
observations and macroscopic models. Importantly, the $k^4$ Rayleigh
contribution derived here does not arise from harmonic disorder or elastic
heterogeneity effects and it is the dominant mechanism for sound attenuation in
amorphous solids as recently suggested by molecular simulations.",2110.13446v2
2021-11-21,Energy Transport in 1-Dimensional Oscillator Arrays With Hysteretic Damping,"Energy transport in 1-dimensional oscillator arrays has been extensively
studied to date in the conservative case, as well as under weak viscous
damping. When driven at one end by a sinusoidal force, such arrays are known to
exhibit the phenomenon of supratransmission, i.e. a sudden energy surge above a
critical driving amplitude. In this paper, we study 1-dimensional oscillator
chains in the presence of hysteretic damping, and include nonlinear stiffness
forces that are important for many materials at high energies. We first employ
Reid's model of local hysteretic damping, and then study a new model of nearest
neighbor dependent hysteretic damping to compare their supratransmission and
wave packet spreading properties in a deterministic as well as stochastic
setting. The results have important quantitative differences, which should be
helpful when comparing the merits of the two models in specific engineering
applications.",2111.10816v3
2021-12-15,An Innovative Transverse Emittance Cooling Technique using a Laser-Plasma Wiggler,"We propose an innovative beam cooling scheme based on laser driven plasma
wakefields to address the challenge of high luminosity generation for a future
linear collider. For linear colliders, beam cooling is realised by means of
damping rings equipped with wiggler magnets and accelerating cavities. This
scheme ensures systematic reduction of phase space volume through synchrotron
radiation emission whilst compensating for longitudinal momentum loss via an
accelerating cavity. In this paper, the concept of a plasma wiggler and its
effective model analogous to a magnetic wiggler are introduced; relation of
plasma wiggler characteristics with damping properties are demonstrated;
underpinning particle-in-cell simulations for laser propagation optimisation
are presented. The oscillation of transverse wakefields and resulting
sinusoidal probe beam trajectory are numerically demonstrated. The formation of
an order of magnitude larger effective wiggler field compared to conventional
wigglers is successfully illustrated. Potential damping ring designs on the
basis of this novel plasma-based technology are presented and performance in
terms of damping times and footprint was compared to an existing conventional
damping ring design.",2112.08163v1
2021-12-21,ISS-Based Robustness to Various Neglected Damping Mechanisms for the 1-D Wave PDE,"This paper is devoted to the study of the robustness properties of the 1-D
wave equation for an elastic vibrating string under four different damping
mechanisms that are usually neglected in the study of the wave equation: (i)
friction with the surrounding medium of the string (or viscous damping), (ii)
thermoelastic phenomena (or thermal damping), (iii) internal friction of the
string (or Kelvin-Voigt damping), and (iv) friction at the free end of the
string (the so-called passive damper). The passive damper is also the simplest
boundary feedback law that guarantees exponential stability for the string. We
study robustness with respect to distributed inputs and boundary disturbances
in the context of Input-to-State Stability (ISS). By constructing appropriate
ISS Lyapunov functionals, we prove the ISS property expressed in various
spatial norms.",2112.11287v1
2022-01-22,Effect of MagneticField on the Damping Behavior of a Ferrofluid based Damper,"This paper is an extension of our earlier work where we had reported a proof
of concept for a ferrofluid based damper. The damper used ferrofluid as damping
medium and it was seen that damping efficiency of the damper changes on
application of magnetic field. The present paper deals with a systematic study
of the effect of magnetic field on the damping efficiency of the damper.
Results of these studies are reported. It is seen that damping ratio varies
linearly with magnetic field ({\zeta} / H = 0.028 per kG) for magnetic field in
range of 0.0 to 4.5 kG. It may be mentioned that ferrofluid is different from
magnetorheological fluid even though both of them are magnetic field-responsive
fluids. The ferrofluid-dampers are better suited than MR Fluid-dampers for
their use in automobiles.",2201.09027v1
2022-01-28,Machine learning-based method of calorimeter saturation correction for helium flux analysis with DAMPE experiment,"DAMPE is a space-borne experiment for the measurement of the cosmic-ray
fluxes at energies up to around 100 TeV per nucleon. At energies above several
tens of TeV, the electronics of DAMPE calorimeter would saturate, leaving
certain bars with no energy recorded. In the present work we discuss the
application of machine learning techniques for the treatment of DAMPE data, to
compensate the calorimeter energy lost by saturation.",2201.12185v3
2022-03-10,Accelerated gradient methods combining Tikhonov regularization with geometric damping driven by the Hessian,"In a Hilbert setting, for convex differentiable optimization, we consider
accelerated gradient dynamics combining Tikhonov regularization with
Hessian-driven damping. The Tikhonov regularization parameter is assumed to
tend to zero as time tends to infinity, which preserves equilibria. The
presence of the Tikhonov regularization term induces a strong convexity
property which vanishes asymptotically. To take advantage of the exponential
convergence rates attached to the heavy ball method in the strongly convex
case, we consider the inertial dynamic where the viscous damping coefficient is
taken proportional to the square root of the Tikhonov regularization parameter,
and therefore also converges towards zero. Moreover, the dynamic involves a
geometric damping which is driven by the Hessian of the function to be
minimized, which induces a significant attenuation of the oscillations. Under
an appropriate tuning of the parameters, based on Lyapunov's analysis, we show
that the trajectories have at the same time several remarkable properties: they
provide fast convergence of values, fast convergence of gradients towards zero,
and strong convergence to the minimum norm minimizer. This study extends a
previous paper by the authors where similar issues were examined but without
the presence of Hessian driven damping.",2203.05457v2
2022-04-01,On the Importance of High-Frequency Damping in High-Order Conservative Finite-Difference Schemes for Viscous Fluxes,"This paper discusses the importance of high-frequency damping in high-order
conservative finite-difference schemes for viscous terms in the Navier-Stokes
equations. Investigating nonlinear instability encountered in a high-resolution
viscous shock-tube simulation, we have discovered that a modification to the
viscous scheme rather than the inviscid scheme resolves a problem with spurious
oscillations around shocks. The modification introduces a term responsible for
high-frequency damping that is missing in a conservative high-order viscous
scheme. The importance of damping has been known for schemes designed for
unstructured grids. However, it has not been recognized well in very high-order
difference schemes, especially in conservative difference schemes. Here, we
discuss how it is easily missed in a conservative scheme and how to improve
such schemes by a suitably designed damping term.",2204.00393v1
2022-05-13,Precession dynamics of a small magnet with non-Markovian damping: Theoretical proposal for an experiment to determine the correlation time,"Recent advances in experimental techniques have made it possible to
manipulate and measure the magnetization dynamics on the femtosecond time scale
which is the same order as the correlation time of the bath degrees of freedom.
In the equations of motion of magnetization, the correlation of the bath is
represented by the non-Markovian damping. For development of the science and
technologies based on the ultrafast magnetization dynamics it is important to
understand how the magnetization dynamics depend on the correlation time. It is
also important to determine the correlation time experimentally. Here we study
the precession dynamics of a small magnet with the non-Markovian damping.
Extending the theoretical analysis of Miyazaki and Seki [J. Chem. Phys. 108,
7052 (1998)] we obtain analytical expressions of the precession angular
velocity and the effective damping constant for any values of the correlation
time under assumption of small Gilbert damping constant. We also propose a
possible experiment for determination of the correlation time.",2205.06399v1
2022-06-20,Stability and Damping in the Disks of Massive Galaxies,"After their initial formation, disk galaxies are observed to be rotationally
stable over periods of >6 Gyr, implying that any large velocity disturbances of
stars and gas clouds are damped rapidly on the timescale of their rotation.
However, it is also known that despite this damping, there must be a degree of
random local motion to stabilize the orbits against degenerate collapse. A
mechanism for such damping is proposed by a combination of inter-stellar
gravitational interactions, and interactions with the Oort clouds and exo-Oort
objects associated with each star. Analysis of the gravitational interactions
between two stars is a three-body problem, because the stars are also in orbit
round the large virtual mass of the galaxy. These mechanisms may produce rapid
damping of large perturbations within a time period that is short on the scale
of observational look-back time, but long on the scale of the disk rotational
period for stars with small perturbations. This mechanism may also account for
the locally observed mean perturbations in the Milky Way of 8-15~km/s for
younger stars and 20-30~km/s for older stars.",2206.09671v2
2022-08-25,The Effect of Frequency Droop Damping on System Parameters and Battery Sizing During Load Change Condition,"Inverter-based resources (IBR) have been widely studied for their advantages
on the current power systems. This increase in the penetration of renewable
energy has raised some concerns about the stability of the existing grid.
Historically, power systems are dominated by synchronous generators that can
easily react to system instability due to high inertia and damping
characteristics. However, with IBR, the control of the inverter plays a crucial
role in contributing to the system stability and enhancing the functionality of
the inverters. One of these novel control methods is droop control. Droop
characteristics are used to control voltage, frequency, and active and reactive
power. This paper presents the impact of frequency droop damping on system
frequency, real power, and the rate of change of frequency with distributed
energy resources. Also, battery sizing is suggested based on the results. The
results also show the need for optimal selection for the frequency droop
damping to fulfill the appropriate battery size in terms of cost and
performance. The simulations are carried out in an electromagnetic transient
program (EMTP)",2208.12291v1
2022-09-15,Superfluid $^4$He as a rigorous test bench for different damping models in nanoelectromechanical resonators,"We have used nanoelectromechanical resonators to probe superfluid $^4$He at
different temperature regimes, spanning over four orders of magnitude in
damping. These regimes are characterized by the mechanisms which provide the
dominant contributions to damping and the shift of the resonance frequency:
tunneling two level systems at the lowest temperatures, ballistic phonons and
rotons at few hundred mK, and laminar drag in the two-fluid regime below the
superfluid transition temperature as well as in the normal fluid. Immersing the
nanoelectromechanical resonators in fluid increases their effective mass
substantially, decreasing their resonance frequency. Dissipationless superflow
gives rise to a unique possibility to dramatically change the mechanical
resonance frequency in situ, allowing rigorous tests on different damping
models in mechanical resonators. We apply this method to characterize tunneling
two-level system losses and magnetomotive damping in the devices.",2209.07229v2
2022-10-16,Magnetic damping anisotropy in the two-dimensional van der Waals material Fe$_3$GeTe$_2$ from first principles,"Magnetization relaxation in the two-dimensional itinerant ferromagnetic van
der Waals material Fe$_3$GeTe$_2$, below the Curie temperature, is
fundamentally important for applications to low-dimensional spintronics
devices. We use first-principles scattering theory to calculate the
temperature-dependent Gilbert damping for bulk and single-layer Fe$_3$GeTe$_2$.
The calculated damping frequency of bulk Fe$_3$GeTe$_2$ increases monotonically
with temperature because of the dominance of resistivitylike behavior. By
contrast, a very weak temperature dependence is found for the damping frequency
of a single layer, which is attributed to strong surface scattering in this
highly confined geometry. A systematic study of the damping anisotropy reveals
that orientational anisotropy is present in both bulk and single-layer
Fe3GeTe2. Rotational anisotropy is significant at low temperatures for both the
bulk and a single layer and is gradually diminished by temperature-induced
disorder. The rotational anisotropy can be significantly enhanced by up to 430%
in gated single-layer Fe$_3$GeTe$_2$.",2210.08429v1
2022-11-08,On the injection scale of the turbulence in the partially ionized very local interstellar medium,"The cascade of magnetohydrodynamic (MHD) turbulence is subject to ion-neutral
collisional damping and neutral viscous damping in the partially ionized
interstellar medium. By examining the damping effects in the warm and partially
ionized local interstellar medium, we find that the interstellar turbulence is
damped by neutral viscosity at $\sim 261$ au and cannot account for the
turbulent magnetic fluctuations detected by Voyager 1 and 2. The MHD turbulence
measured by Voyager in the very local interstellar medium (VLISM) should be
locally injected in the regime where ions are decoupled from neutrals for its
cascade to survive the damping effects. With the imposed ion-neutral decoupling
condition, and the strong turbulence condition for the observed Kolmogorov
magnetic energy spectrum, we find that the turbulence in the VLISM is
sub-Alfv\'{e}nic, and its largest possible injection scale is $\sim 194$ au.",2211.04496v1
2022-12-11,"The overtone level spacing of a black hole quasinormal frequencies: a fingerprint of a local $SL(2,\mathbb{R})$ symmetry","The imaginary part of the quasinormal frequencies spectrum for a static and
spherically symmetric black hole is analytically known to be equally spaced,
both for the highly damped and the weakly damped families of quasinormal modes.
Some interesting attempts have been made in the last twenty years to understand
in simple ways this level spacing for the only case of highly damped
quasinormal frequencies. Here, we show that the overtone level spacing, for
both the highly damped and weakly damped families of quasinormal modes, can
simply be understood as a fingerprint of a hidden local $SL(2,\mathbb{R})$
symmetry, near different regions of the black hole spacetime, i.e. the
near-horizon and the near-photon sphere regions.",2212.05538v1
2022-12-15,Formation of shifted shock for the 3D compressible Euler equations with time-dependent damping,"In this paper, we show the shock formation to the compressible Euler
equations with time-dependent damping $\frac{a\p u}{(1+t)^{\lam}}$ in three
spatial dimensions without any symmetry conditions. It's well-known that for
$\lam>1$, the damping is too weak to prevent the shock formation for suitably
large data. However, the classical results only showed the finite existence of
the solution. Follow the work by D.Christodoulou in\cite{christodoulou2007},
starting from the initial isentropic and irrotational short pulse data, we show
the formation of shock is characterized by the collapse of the characteristic
hypersurfaces and the vanishing of the inverse foliation density function
$\mu$, at which the first derivatives of the velocity and the density blow up,
and the lifespan $T_{\ast}(a,\lam)$ is exponentially large. Moreover, the
damping effect will shift the time of shock formation $T_{\ast}$. The methods
in the paper can also be extended to the Euler equations with general
time-decay damping.",2212.07828v1
2023-01-15,Damped-driven system of bouncing droplets leading to deterministic diffusive behavior,"Damped-driven systems are ubiquitous in science, however the damping and
driving mechanisms are often quite convoluted. This manuscript presents an
experimental and theoretical investigation of a fluidic droplet on a vertically
vibrating fluid bath as a damped-driven system. We study a fluidic droplet in
an annular cavity with the fluid bath forced above the Faraday wave threshold.
We model the droplet as a kinematic point particle in air and as inelastic
collisions during impact with the bath. In both experiments and the model the
droplet is observed to chaotically change velocity with a Gaussian
distribution. Finally, the statistical distributions from experiments and
theory are analyzed. Incredibly, this simple deterministic interaction of
damping and driving of the droplet leads to more complex Brownian-like and
Levy-like behavior.",2301.06041v2
2023-03-01,Generation of intraparticle quantum correlations in amplitude damping channel and its robustness,"Quantum correlations between two or more different degrees of freedom of the
same particle is sometimes referred to as intraparticle entanglement. In this
work, we study these intra-particle correlations between two different degrees
of freedom under various decoherence channels viz. amplitude damping,
depolarising and phase damping channels. We observe a unique feature of the
amplitude damping channel, wherein entanglement is shown to arise starting from
separable states. In case of non maximally entangled input states, in addition
to entanglement sudden death, the creation of entanglement is also observed,
having an asymptotic decay over a long time. These counter-intuitive behaviours
arise due to the subtle interplay of channel and input state parameters, and
are not seen for interparticle entanglement without consideration of
non-Markovian noise. It is also not observed for maximally entangled input
states. Furthermore, investigation of entanglement evolution in phase damping
and depolarizing channels shows its robustness against decoherence as compared
to interparticle entanglement.",2303.01238v1
2023-03-07,Electrically tunable Gilbert damping in van der Waals heterostructures of two-dimensional ferromagnetic metals and ferroelectrics,"Tuning the Gilbert damping of ferromagnetic (FM) metals via a nonvolatile way
is of importance to exploit and design next-generation novel spintronic
devices. Through systematical first-principles calculations, we study the
magnetic properties of the van der Waals heterostructure of two-dimensional FM
metal CrTe2 and ferroelectric (FE) In2Te3 monolayers. The ferromagnetism of
CrTe2 is maintained in CrTe2/In2Te3 and its magnetic easy axis can be switched
from in-plane to out-of-plane by reversing the FE polarization of In2Te3.
Excitingly, we find that the Gilbert damping of CrTe2 is tunable when the FE
polarization of In2Te3 is reversed from upward to downward. By analyzing the
k-dependent contributions to the Gilbert damping, we unravel that such
tunability results from the changed intersections between the bands of CrTe2
and Fermi level on the reversal of the FE polarizations of In2Te3 in
CrTe2/In2Te3. Our work provides an appealing way to electrically tailor Gilbert
dampings of two-dimensional FM metals by contacting them with ferroelectrics.",2303.03852v1
2023-03-16,Quantum Brownian Motion in the Caldeira-Leggett Model with a Damped Environment,"We model a quantum system coupled to an environment of damped harmonic
oscillators by following the approach of Caldeira-Leggett and adopting the
Caldirola-Kanai Lagrangian for the bath oscillators. In deriving the master
equation of the quantum system of interest (a particle in a general potential),
we show that the potential is modified non-trivially by a new inverted harmonic
oscillator term, induced by the damping of the bath oscillators. We analyze
numerically the case of a particle in a double-well potential, and find that
this modification changes both the rate of decoherence at short times and the
well-transfer probability at longer times. We also identify a simple rescaling
condition that keeps the potential fixed despite changes in the environmental
damping. Here, the increase of environmental damping leads to a slowing of
decoherence.",2303.09516v1
2023-03-22,A Numerical Study of Landau Damping with PETSc-PIC,"We present a study of the standard plasma physics test, Landau damping, using
the Particle-In-Cell (PIC) algorithm. The Landau damping phenomenon consists of
the damping of small oscillations in plasmas without collisions. In the PIC
method, a hybrid discretization is constructed with a grid of finitely
supported basis functions to represent the electric, magnetic and/or
gravitational fields, and a distribution of delta functions to represent the
particle field. Approximations to the dispersion relation are found to be
inadequate in accurately calculating values for the electric field frequency
and damping rate when parameters of the physical system, such as the plasma
frequency or thermal velocity, are varied. We present a full derivation and
numerical solution for the dispersion relation, and verify the PETSC-PIC
numerical solutions to the Vlasov-Poisson for a large range of wave numbers and
charge densities.",2303.12620v1
2023-04-07,Shifted shock formation for the 3D compressible Euler equations with damping and variation of the vorticity,"In this paper, we consider the shock formation problem for the
3-dimensional(3D) compressible Euler equations with damping inspired by the
work \cite{BSV3Dfulleuler}. It will be shown that for a class of large data,
the damping can not prevent the formation of point shock, and the damping
effect shifts the shock time and the wave amplitude while the shock location
and the blow up direction remain the same with the information of this point
shock being computed explicitly. Moreover, the vorticity is concentrated in the
non-blow-up direction, which varies exponentially due to the damping effect.
Our proof is based on the estimates for the modulated self-similar variables
and lower bounds for the Lagrangian trajectories.",2304.03506v2
2023-07-05,Bayesian evidence for two slow-wave damping models in hot coronal loops,"We compute the evidence in favour of two models, one based on field-aligned
thermal conduction alone and another that includes thermal misbalance as well,
in explaining the damping of slow magneto-acoustic waves in hot coronal loops.
Our analysis is based on the computation of the marginal likelihood and the
Bayes factor for the two damping models. We quantify their merit in explaining
the apparent relationship between slow mode periods and damping times, measured
with SOHO/SUMER in a set of hot coronal loops. The results indicate evidence in
favour of the model with thermal misbalance in the majority of the sample, with
a small population of loops for which thermal conduction alone is more
plausible. The apparent possibility of two different regimes of slow-wave
damping, if due to differences between the loops of host active regions and/or
the photospheric dynamics, may help with revealing the coronal heating
mechanism.",2307.02439v1
2023-07-24,From characteristic functions to multivariate distribution functions and European option prices by the damped COS method,"We provide a unified framework for the computation of the distribution
function and the computation of prices of financial options from the
characteristic function of some density by the COS method. The classical COS
method is numerically very efficient in one-dimension but cannot deal very well
with certain financial options in general dimensions. Therefore, we introduce
the damped COS method which can handle a large class of integrands very
efficiently. We prove the convergence of the (damped) COS method and study its
order of convergence. The (damped) COS method converges exponentially if the
characteristic function decays exponentially. To apply the (damped) COS method,
one has to specify two parameters: a truncation range for the multivariate
density and the number of terms to approximate the truncated density by a
cosine series. We provide an explicit formula for the truncation range and an
implicit formula for the number of terms. Numerical experiments up to five
dimensions confirm the theoretical results.",2307.12843v6
2023-07-26,A Nonlinear Damped Metamaterial: Wideband Attenuation with Nonlinear Bandgap and Modal Dissipation,"In this paper, we incorporate the effect of nonlinear damping with the
concept of locally resonant metamaterials to enable vibration attenuation
beyond the conventional bandgap range. The proposed design combines a linear
host cantilever beam and periodically distributed inertia amplifiers as
nonlinear local resonators. The geometric nonlinearity induced by the inertia
amplifiers causes an amplitude-dependent nonlinear damping effect. Through the
implementation of both modal superposition and numerical harmonic methods the
finite nonlinear metamaterial is accurately modelled. The resulting nonlinear
frequency response reveals the bandgap is both amplitude-dependent and
broadened. Furthermore, the modal frequencies are also attenuated due to the
nonlinear damping effect. The theoretical results are validated experimentally.
By embedding the nonlinear damping effect into locally resonant metamaterials,
wideband attenuation of the proposed metamaterial is achieved, which opens new
possibilities for versatile metamaterials beyond the limit of their linear
counterparts.",2307.14165v2
2023-07-28,Premature jump-down mimicks nonlinear damping in nanoresonators,"Recent experiments on nano-resonators in a bistable regime use the
`jump-down' point between states to infer mechanical properties of the membrane
or a load, but often suggest the presence of some nonlinear damping. Motivated
by such experiments, we develop a mechanical model of a membrane subject to a
uniform, oscillatory load and linear damping. We solve this model numerically
and compare its jump-down behaviour with standard asymptotic predictions for a
one-dimensional Duffing oscillator with strain stiffening. We show that the
axisymmetric, but spatially-varying, problem can be mapped to the Duffing
problem with coefficients determined rationally from the model's Partial
Differential Equations. However, we also show that jump-down happens earlier
than expected (i.e.~at lower frequency, and with a smaller oscillation
amplitude). Although this premature jump-down is often interpreted as the
signature of a nonlinear damping in experiments, its appearance in numerical
simulations with only linear damping suggests instead that indicate that the
limitations of asymptotic results may, at least sometimes, be the cause. We
therefore suggest that care should be exercised in interpreting the results of
nano-resonator experiments.",2307.15656v1
2023-09-22,Long time energy averages and a lower resolvent estimate for damped waves,"We consider the damped wave equation on a compact manifold. We propose
different ways of measuring decay of the energy (time averages of lower energy
levels, decay for frequency localized data...) and exhibit links with resolvent
estimates on the imaginary axis. As an application we prove a universal
logarithmic lower resolvent bound on the imaginary axis for the damped wave
operator when the Geometric Control Condition (GCC) is not satisfied. This is
to be compared to the uniform boundedness of the resolvent on that set when GCC
holds. The proofs rely on (i) various (re-)formulations of the damped wave
equation as a conservative hyperbolic part perturbed by a lower order damping
term;(ii) a ""Plancherel-in-time"" argument as in classical proofs of the
Gearhart-Huang-Pr{\""u}ss theorem; and (iii) an idea of Bony-Burq-Ramond of
propagating a coherent state along an undamped trajectory up to Ehrenfest time.",2309.12709v1
2023-10-11,Damping Density of an Absorptive Shoebox Room Derived from the Image-Source Method,"The image-source method is widely applied to compute room impulse responses
(RIRs) of shoebox rooms with arbitrary absorption. However, with increasing RIR
lengths, the number of image sources grows rapidly, leading to slow
computation. In this paper, we derive a closed-form expression for the damping
density, which characterizes the overall multi-slope energy decay. The
omnidirectional energy decay over time is directly derived from the damping
density. The resulting energy decay model accurately matches the late
reverberation simulated via the image-source method. The proposed model allows
the fast stochastic synthesis of late reverberation by shaping noise with the
energy envelope. Simulations of various wall damping coefficients demonstrate
the model's accuracy. The proposed model consistently outperforms the energy
decay prediction accuracy compared to a state-of-the-art approximation method.
The paper elaborates on the proposed damping density's applicability to
modeling multi-sloped sound energy decay, predicting reverberation time in
non-diffuse sound fields, and fast frequency-dependent RIR synthesis.",2310.07363v1
2023-10-14,Exploring Damping Effect of Inner Control Loops for Grid-Forming VSCs,"This paper presents an analytical approach to explore the damping effect of
inner loops on grid-forming converters. First, an impedance model is proposed
to characterize the behaviors of inner loops, thereby illustrating their
influence on output impedance shaping. Then, based on the impedance
representation, the complex torque coefficient method is employed to assess the
contribution of inner loops to system damping. The interactions among inner
loops, outer loops, and the ac grid are analyzed. It reveals that inner loops
shape the electrical damping torque coefficient and consequently influence both
synchronous and sub-synchronous oscillation modes. The virtual admittance and
current control-based inner-loop scheme is employed to illustrate the proposed
analytical approach. The case study comprises the analysis of impedance
profiles, the analysis of damping torque contributed by inner loops under
various grid strengths, and the comparison between dq-frame and
{\alpha}\b{eta}-frame realizations of inner loops. Finally, simulation and
experimental tests collaborate with theoretical approaches and findings.",2310.09660v1
2023-10-24,Frictional weakening of a granular sheared layer due to viscous rolling revealed by Discrete Element Modeling,"Considering a 3D sheared granular layer modeled with discrete elements, it is
well known the rolling resistance significantly influences the mechanical
behavior. Even if the rolling resistance role has been deeply investigated as
it is commonly used to represent the the roughness of the grains and the
interparticle locking, the role of rolling viscous damping coefficient has been
largely overlooked so far. This parameter is rarely used or only to dissipate
the energy and to converge numerically. This paper revisits the physical role
of those coefficients with a parametric study of the rolling friction and the
rolling damping for a sheared layer at different shear speeds and different
confinement pressures. It has been observed that the damping coefficient
induces a frictional weakening. Hence, competition between the rolling
resistance and the rolling damping occurs. Angular resistance aims to avoid
grains rolling, decreasing the difference between the angular velocities of
grains. Whereas, angular damping acts in the opposite, avoiding a change in the
difference between the angular velocities of grains. In consequence, grains
keep rolling and the sample strength decreases. This effect must be considered
to not overestimate the frictional response of a granular layer.",2310.15945v1
2023-12-12,Coordination of Damping Controllers: A Data-Informed Approach for Adaptability,"This work proposes a data-informed approach for an adaptable coordination of
damping controllers. The novel concept of coordination is based on minimizing
the Total Action, a single metric that measures the system's dynamic response
post-disturbance. This is a performance measure based on the physics of the
power system, which encapsulates the oscillation energy related to synchronous
generators. Deep learning theory is used to propose a Total Action function
approximator, which captures the relationship between the system wide-area
measurements, the status of damping controllers, and the conditions of the
disturbance. By commissioning the switching status (on/off) of damping
controllers in real-time, the oscillation energy is reduced, enhancing the
power system stability. The concept is tested in the Western North America
Power System (wNAPS) and compared with a model-based approach for the
coordination of damping controllers. The data-informed coordination outperforms
the model-based approach, demonstrating exceptional adaptability and
performance to handle multi-modal events. The proposed scheme shows outstanding
reductions in low-frequency oscillations even under various operating
conditions, fault locations, and time delay considerations.",2312.07739v1
2024-01-26,Efficient Control of Magnetization Dynamics Via W/CuO$_\text{x}$ Interface,"Magnetization dynamics, which determine the speed of magnetization switching
and spin information propagation, play a central role in modern spintronics.
Gaining its control will satisfy the different needs of various spintronic
devices. In this work, we demonstrate that the surface oxidized Cu
(CuO$_\text{x}$) can be employed for the tunability of magnetization dynamics
of ferromagnet (FM)/heavy metal (HM) bilayer system. The capping CuO$_\text{x}$
layer in CoFeB/W/CuO$_\text{x}$ trilayer reduces the magnetic damping value in
comparison with the CoFeB/W bilayer. The magnetic damping even becomes lower
than that of the CoFeB/CuO$_\text{x}$ by ~ 16% inferring the stabilization of
anti-damping phenomena. Further, the reduction in damping is accompanied by a
very small reduction in the spin pumping-induced output DC voltage in the
CoFeB/W/CuO$_\text{x}$ trilayer. The simultaneous observation of anti-damping
and spin-to-charge conversion can be attributed to the orbital Rashba effect
observed at the HM/CuO$_\text{x}$ interface. Our experimental findings
illustrate that the cost-effective CuO$_\text{x}$ can be employed as an
integral part of modern spintronics devices owing to its rich underneath
spin-orbital physics.",2401.14708v1
2024-02-08,The stability analysis based on viscous theory of Faraday waves in Hele-Shaw cells,"The linear instability of Faraday waves in Hele-Shaw cells is investigated
with consideration of the viscosity of fluids after gap-averaging the governing
equations due to the damping from two lateral walls and the dynamic behavior of
contact angle. A new hydrodynamic model is thus derived and solved
semi-analytically. The contribution of viscosity to critical acceleration
amplitude is slight compared to other factors associated with dissipation, and
the potential flow theory is sufficient to describe onset based on the present
study, but the rotational component of velocity can change the timing of onset
largely, which paradoxically comes from the viscosity. The model degenerates
into a novel damped Mathieu equation if the viscosity is dropped with two
damping terms referring to the gap-averaged damping and dissipation from
dynamic contact angle, respectively. The former increases when the gap size
decreases, and the latter grows as frequency rises. When it comes to the
dispersion relation of Faraday waves, an unusual detuning emerges due to the
imaginary part of the gap-averaged damping.",2402.05505v2
2024-02-09,Damping of density oscillations from bulk viscosity in quark matter,"We study the damping of density oscillations in the quark matter phase that
might occur in compact stars. To this end we compute the bulk viscosity and the
associated damping time in three-flavor quark matter, considering both
nonleptonic and semileptonic electroweak processes. We use two different
equations of state of quark matter, more precisely, the MIT bag model and
perturbative QCD, including the leading order corrections in the strong
coupling constant. We analyze the dependence of our results on the density,
temperature and value of strange quark mass in each case. We then find that the
maximum of the bulk viscosity is in the range of temperature from 0.01 to 0.1
MeV for frequencies around 1 kHz, while the associated minimal damping times of
the density oscillations at those temperatures might be in the range of few to
hundreds milliseconds. Our results suggest that bulk viscous damping might be
relevant in the post-merger phase after the collision of two neutron stars if
deconfined matter is achieved in the process.",2402.06595v1
2024-04-08,Stability Enhancement of LCL-Type Grid-Following Inverters Using Capacitor Voltage Active Damping,"An LCL filter offers superior attenuation for high-frequency harmonics for
three-phase grid-following inverters compared to LC and L filters. However, it
also introduces an inherent resonance peak, which can lead to power quality
issues or even instability of the inverter control system. Active damping (AD)
is widely employed to effectively mitigate this resonance. Capacitor voltage
feedback (CVF) and capacitor current feedback (CCF) are effective AD methods
for LCL resonance damping. CVF is preferred due to its lower sensor requirement
compared to CCF. However, a derivative term appears in the active damping loop,
which introduces high-frequency noise into the system. This paper proposes a
noise-immune approach by replacing the derivative term with a discrete function
suitable for digital implementation. The LCL resonance can be damped
effectively, resulting in enhanced stability of the inverter control system.
Simulation results verify the proposed effectiveness of the method with grid
inductance variation and weak grid conditions",2404.05640v1
2001-06-26,Violation of Lorentz Invariance and neutral component of UHECR,"The observed clustering of ultra-high energy cosmic rays suggests the
existence of a neutral component. The models with violation of Lorentz
invariance may explain this component by neutrons becoming stable above some
threshold energy E_0. The protons, in turn, may become unstable above some
energy E_1>E_0. We calculate the dependence of the threshold energies E_0 and
E_1 on the parameters of the model and find E_1/E_0\gsim 1.5. We argue that the
characteristic threshold behavior of charged and neutral components may be used
as the specific signature of models with violation of Lorentz invariance. The
existence of the neutron stability threshold E_0 can be investigated with
already existing data.",0106472v1
2002-02-21,Lorentz Invariance Violation and the QED Formation Length,"It was recently suggested that possible small volations of Lorentz invariance
could explain the existence of UHECR beyond the GZK cutoff and the observations
of multi-TeV gamma-rays from Mkn 501. Our analysis of Lorentz-violating
kinematics shows that in addition to the modified threshold conditions solving
cosmic ray puzzles we should expect a strong suppression of electromagnetic
processes like bremsstrahlung and pair creation. This leads to drastic effects
in electron-photon cascade development in the atmosphere and in detectors.",0202388v2
2004-03-27,Cosmic rays acceleration at ultrarelativistic subshocks,"We present the model of cosmic rays acceleration at ultrarelativistic
subshocks and confront it with the observations of gamma-ray bursts and
blazars. We investigate cosmic rays acceleration in shocks with Lorentz factors
in the range 3 - 40. We show that fluctuations of the magnetic field downstream
of the shock do not play an important role in the acceleration process. Results
of numerical simulations for shocks with considered Lorentz factors and
perpendicular magnetic field inclinations are presented. We fit the derived
particle energy spectral index dependence on fluctuations of the magnetic field
upstream and Lorentz factor of the shock with a function.",0403640v1
1994-12-26,Lyapunov Exponents and KS Entropy for the Lorentz Gas at Low Densities,"The Lyapunov exponents and the KS entropy for a two dimensional Lorentz gas
at low densities are defined for general non-equilibrium states and calculated
with the use of a Lorentz-Boltzmann type equation. In equilibrium the density
dependence of these quantities predicted by Krylov is recovered and explicit
expressions are obtained. The relationship between the KS entropy, Lyapunov
exponents, and escape rate, conjectured by Gaspard and Nicolis for
non-equilibrium systems is confirmed and generalized.",9412012v1
1996-07-14,The Computational Complexity of the Lorentz Lattice Gas,"The Lorentz lattice gas is studied from the perspective of computational
complexity theory. It is shown that using massive parallelism, particle
trajectories can be simulated in a time that scales logarithmically in the
length of the trajectory. This result characterizes the ``logical depth"" of the
Lorentz lattice gas and allows us to compare it to other models in statistical
physics.",9607001v1
1996-11-11,Lorentz Group in Condensed Matter Physics,"It is shown that the Lorentz group plays prominent roles in at least two
areas in condensed matter physics, namely in the Bogoliubov transformation and
optical filters. It is pointed out that the underlying symmetry of the
Bogoliubov transformation is that of two coupled oscillators, and that the
underlying symmetry of two coupled oscillators in that of the group $O(3,3)$.
The Lorentz group is also shown to be the underlying symmetry group for the
Jones matrix formalism which is standard language for optical filters.",9611082v1
2005-07-26,Optical Magnetoelectric Effect in Multiferroic Materials: Evidence for a Lorentz Force Acting on a Ray of Light,"We theoretically propose that the optical analog of a Lorentz force acting on
a ray of light is realized in multiferroic materials such as GaFeO$_3$ showing
the magnetoelectric effect. The toroidal moment plays the role of a ``vector
potential"" while its rotation corresponds to a ""magnetic field"" for photons.
Hence, the light is subject to the Lorentz force when propagating through the
domain wall region of the ferromagnetic or ferroelectric order. A realistic
estimate on the magnitude of this effect is given.",0507593v2
1999-01-14,Seed Magnetic Fields from the Breaking of Lorentz Invariance,"Spontaneous breaking of Lorentz invariance may take place in string theories,
possibly endowing the photon with a mass. This leads to the breaking of the
conformal symmetry of the electromagnetic action allowing for the generation
within inflationary scenarios of magnetic fields over $Mpc$ scales. We show
that the generated fields are consistent with amplification by the galactic
dynamo processes and can be as large as to explain the observed galactic
magnetic fields through the collapse of protogalactic clouds.",9901041v1
1999-12-10,An introduction to the Lorentz-Dirac equation,"These notes provide two derivations of the Lorentz-Dirac equation. The first
is patterned after Landau and Lifshitz and is based on the observation that the
half-retarded minus half-advanced potential is entirely responsible for the
radiation-reaction force. The second is patterned after Dirac, and is based
upon considerations of energy-momentum conservation; it relies exclusively on
the retarded potential. The notes conclude with a discussion of the
difficulties associated with the interpretation of the Lorentz-Dirac equation
as an equation of motion for a point charge. The presentation is essentially
self-contained, but the reader is assumed to possess some elements of
differential geometry (necessary for the second derivation only).",9912045v1
2001-10-18,Lorentz violation and Hawking radiation,"Since the event horizon of a black hole is a surface of infinite redshift, it
might be thought that Hawking radiation would be highly sensitive to Lorentz
violation at high energies. In fact, the opposite is true for subluminal
dispersion. For superluminal dispersion, however, the outgoing black hole modes
emanate from the singularity in a state determined by unknown quantum gravity
processes.",0110079v1
2002-11-20,Proper Time Foliations of Lorentz Manifolds,"Some standard definitions and results concerning foliations of dimension one
and codimension one are introduced. A proper time foliation of Minkowski space
is defined and contrasted with the foliation that is defined by the time
coordinate. The extent to which a Lorentz structure on a manifold defines
foliations, and the issues concerning the extension of the proper time
foliation of Minkowski space to a Lorentz manifold are discussed, such as
proper time sections of a geodesic flow.",0211066v1
2003-04-22,The Magueijo-Smolin Group in Doubly-Special Relativity is Linear in Five Dimensions,"Magueijo and Smolin have introduced a modification of the Lorentz group for
the momentum-space transformations in Doubly-Special Relativity. As presented
the group is non-linear, but we show that it is a group of fraction-linear
transformations in 4 dimensional real projective space. We pass to the
associated 5 dimensional linear space and identify the subgroup as a conjugate
of the ordinary Lorentz group, giving the conjugating matrix. Taking the dual
of the 5-space, we identify a subgroup as the Lorentz transformations about a
point different to the origin.",0304079v1
2003-07-15,Lorentz Violations and Euclidean Signature Metrics,"We show that the families of effective actions considered by Jacobson et al.
to study Lorentz invariance violations contain a class of models that represent
pure General Relativity with Euclidean signature. We also point out that some
members of this family of actions preserve Lorentz invariance in a generalized
sense.",0307066v2
2003-11-04,Position space of Doubly Special Relativity,"We consider three possible approaches to formulating coordinate
transformations on position space associated with non-linear Lorentz
transformations on momentum space. The first approach uses the definition of
velocity and gives the standard Lorentz transformation. In the second method,
we translate the behavior in momentum space into position space by means of
Fourier transform. Under certain conditions, it also gives the standard Lorentz
transformation on position space. The third approach investigates the
covariance of the modified Klein-Gordon equation obtained from the dispersion
relation.",0311009v2
2004-04-15,Quantum Gravity Phenomenology and Lorentz Violation,"If quantum gravity violates Lorentz symmetry, the prospects for observational
guidance in understanding quantum gravity improve considerably. This article
briefly reviews previous work on Lorentz violation (LV) and discusses aspects
of the effective field theory framework for parametrizing LV effects. Current
observational constraints on LV are then summarized, focusing on effects in QED
at order E/M_Planck.",0404067v1
2005-08-29,Spacetime symmetries and varying scalars,"This talk discusses the relation between spacetime-dependent scalars, such as
couplings or fields, and the violation of Lorentz symmetry. A specific
cosmological supergravity model demonstrates how scalar fields can acquire
time-dependent expectation values. Within this cosmological background,
excitations of these scalars are governed by a Lorentz-breaking dispersion
relation. The model also contains couplings of the scalars to the
electrodynamics sector leading to the time dependence of both the
fine-structure parameter alpha and the theta angle. Through these couplings,
the variation of the scalars is also associated with Lorentz- and CPT-violating
effects in electromagnetism.",0508122v1
2005-09-16,On the compatibility of Lorentz-metrics with linear connections on 4-dimensional manifolds,"This paper considers 4-dimensional manifolds upon which there is a Lorentz
metric, h, and a symmetric connection and which are originally assumed
unrelated. It then derives sufficient conditions on the metric and connection
(expressed through the curvature tensor) for the connection to be the
Levi-Civita connection of some (local) Lorentz metric, g, and calculates the
relationship between g and h. Some examples are provided which help to assess
the strength of the sufficient conditions derived.",0509067v1
2006-04-10,Macroscopic observables and Lorentz violation in discrete quantum gravity,"This article concerns the fate of local Lorentz invariance in quantum
gravity, particularly for approaches in which a discrete structure replaces
continuum spacetime. Some features of standard quantum mechanics, presented in
a sum-over-histories formulation, are reviewed, and their consequences for such
theories are discussed. It is argued that, if the individual histories of a
theory give bad approximations to macroscopic continuum properties in some
frames, then it is inevitable that the theory violates Lorentz symmetry.",0604040v1
2006-05-07,"Lorentz violation in brane cosmology, accelerated expansion and fundamental constants","The notion of Lorentz violation in four dimensions is extended to a
5-dimensional brane-world scenario by utilizing a dynamical vector field
assumed to point in the bulk direction, with Lorentz invariance holding on the
brane. The cosmological consequences of this theory consisting of the time
variation in the gravitational coupling $G$ and cosmological term $\Lambda_4$
are explored. The brane evolution is addressed by studying the generalized
Friedmann and Raychaudhuri equations. The behavior of the expansion scale
factor is then considered for different possible scenarios where the bulk
cosmological constant is zero, positive or negative.",0605038v1
2007-02-05,Is Torsion a Fundamental Physical Field?,"The local Lorentz group is introduced in flat space-time, where the resulting
Dirac and Yang-Mills equations are found, and then generalized to curved
space-time: if matter is neglected, the Lorentz connection is identified with
the contortion field, while, if matter is taken into account, both the Lorentz
connection and the spinor axial current are illustrated to contribute to the
torsion of space-time.",0702024v1
2007-02-19,Lorentz violation and the speed of gravitational waves in brane-worlds,"Lorentz violation in a brane-world scenario is presented and used to obtain a
relationship between the speed of gravitational waves in the bulk and that on
the brane. Lorentz violating effects would manifest themselves in gravitational
waves travelling with a greater speed in the bulk than on the brane and this
effect is independent of the signature of the extra dimension.",0702103v1
2007-03-16,"Quantum-gravity phenomenology, Lorentz symmetry, and the SME","Violations of spacetime symmetries have recently been identified as promising
signatures for physics underlying the Standard Model. The present talk gives an
overview over various topics in this field: The motivations for
spacetime-symmetry research, including some mechanisms for Lorentz breaking,
are reviewed. An effective field theory called the Standard-Model Extension
(SME) for the description of the resulting low-energy effects is introduced,
and some experimental tests of Lorentz and CPT invariance are listed.",0703089v1
1996-02-29,Lorentz Boosts as Squeeze Transformations and the Parton Picture,"It was shown by Gribov, Ioffe, Pomeranchuk in 1966 and by Ioffe in 1969 that
a space-time picture is needed for the Lorentz deformation of hadronic
interaction region. It is shown that this deformation is a squeeze
transformation. It is shown also that Feynman's parton picture emerges as a
consequence of Lorentz-squeezed hadrons in the quark model.",9602440v1
1997-07-28,Potential regime for heavy quarks dynamics and Lorentz nature of confinement,"Propagation of the heavy quark in the field of a static antiquark source is
studied in the framework of effective Dirac equation. The model of QCD vacuum
is described by bilocal gluonic correlators. In the heavy quark limit the
effective interaction is reduced to the potential one with 5/6 Lorentz scalar
and 1/6 Lorentz vector linear confinement, while spin-orbit term is in
agreement with Eichten-Feinberg-Gromes results. New spin-independent
corrections to the leading confining regime are identified, which arise due to
the nonlocality of the interaction in time direction and quark Zitterbewegung.",9707490v1
1997-10-08,Lorentz Symmetry and the Internal Structure of the Nucleon,"To investigate the internal structure of the nucleon, it is useful to
introduce quantities that do not transform properly under Lorentz symmetry,
such as the four-momentum of the quarks in the nucleon, the amount of the
nucleon spin contributed by quark spin, etc. In this paper, we discuss to what
extent these quantities do provide Lorentz-invariant descriptions of the
nucleon structure.",9710290v1
1999-02-02,Deviations from Lorentz Invariance for Ultrahigh-Energy Fermions,"In a new theory, local Lorentz invariance is a low-energy symmetry which no
longer holds when a fermion energy E is well above 1 TeV. Here we find that the
modified E(p) relation is consistent with observation, and is in fact nearly
the same as in Einstein relativity. On the other hand, there is a strong
modification of the fermion equation of motion and propagator at ultrahigh
energy, which should lead to observable effects.",9902228v1
1999-04-28,CPT and Lorentz Symmetry in Hydrogen and Antihydrogen,"Possibilities for observing signals of CPT and Lorentz violation in the
spectroscopy of hydrogen and antihydrogen are considered. We show that
transitions between the c and d hyperfine sublevels in the 1S state can exhibit
theoretically detectable effects that would be unsuppressed by powers of the
fine-structure constant. This transition may therefore offer some advantages
over 1S-2S two-photon spectroscopy.",9904482v1
1999-05-11,Mapping Lorentz Invariance Violations into Equivalence Principle Violations,"We point out that equivalence principle violations, while not dynamically
equivalent, produce the same kinematical effects as Lorentz invariance
violations for particle processes in a constant gravitational potential. This
allows us to translate many experimental bounds on Lorentz invariance
violations into bounds on equivalence principle violations. The most stringent
bound suggests that a postive signal in an E\""otv\""os experiment may be at
least seven orders of magnitude beyond current technology.",9905301v1
1999-12-21,CPT and Lorentz tests with muons,"Precision experiments with muons are sensitive to Planck-scale CPT and
Lorentz violation that is undetectable in other tests. Existing data on the
muonium ground-state hyperfine structure and on the muon anomalous magnetic
moment could be analyzed to provide dimensionless figures of merit for CPT and
Lorentz violation at the levels of $4\times 10^{-21}$ and $10^{-23}$.",9912451v1
2000-03-22,Searching for Lorentz Violation in the Ground State of Hydrogen,"A theoretical analysis is made of experiments in hydrogen and antihydrogen
that test CPT. We show that these experiments also provide sensitive tests of
Lorentz symmetry for protons and electrons. Both 1S-2S transitions and Zeeman
hyperfine splittings in the ground state are examined. We find that sensitivity
to CPT and Lorentz violation at the level of $10^{-27}$ GeV is attainable.",0003223v1
2000-06-02,Lorentz and CPT Tests in Atomic Systems,"A review of Lorentz and CPT tests performed in atomic systems is presented. A
theoretical framework extending QED in the context of the standard model is
used to analyze a variety of systems. Experimental signatures of possible
Lorentz and CPT violation in these systems are investigated. Estimated bounds
attainable in future experiments and actual bounds obtained in recent
experiments are given.",0006033v1
2000-07-06,Testing Lorentz invariance violations in the tritium beta-decay anomaly,"We consider a Lorentz non-invariant dispersion relation for the neutrino,
which would produce unexpected effects with neutrinos of few eV, exactly where
the tritium beta-decay anomaly is found. We use this anomaly to put bounds on
the violation of Lorentz invariance. We discuss other consequences of this
non-invariant dispersion relation in neutrino experiments and high-energy
cosmic-ray physics.",0007057v2
2002-01-07,Atomic Probes of Noncommutative Field Theory,"We consider the role of Lorentz symmetry in noncommutative field theory. We
find that a Lorentz-violating standard-model extension involving ordinary
fields is general enough to include any realisitc noncommutative field theory
as a subset. This leads to various theoretical consequences, as well as bounds
from existing experiments at the level of (10 TeV)$^{-2}$ on the scale of the
noncommutativity parameter.",0201039v1
2002-01-28,CPT Violation Implies Violation of Lorentz Invariance,"An interacting theory that violates CPT invariance necessarily violates
Lorentz invariance. On the other hand, CPT invariance is not sufficient for
out-of-cone Lorentz invariance. Theories that violate CPT by having different
particle and antiparticle masses must be nonlocal.",0201258v3
2002-09-23,Investigating Lorentz and CPT Symmetry with Antihydrogen,"This talk discusses theoretical aspects of tests of CPT and Lorentz Symmetry
that will in principle be possible with trapped antihydrogen. The framework is
the standard-model extension, which admits minuscule violations of CPT and
Lorentz symmetry in a general manner without giving up other features of the
standard model of particle physics. Spectroscopic transitions in hydrogen and
antihydrogen that exhibit leading-order effects are identified. Such
comparisons of spectral frequencies in antimatter with the corresponding
frequencies in regular matter will bound parameter combinations that are not
accessible with regular-matter atoms alone.",0209251v1
2003-01-22,Threshold Effects and Lorentz Symmetry,"Evidence on the violation of Lorentz symmetry arises from the observation of
cosmic rays with energies beyond the GZK cutoff, $E_{GZK} \simeq 4 \times
10^{19} eV$, from the apparent transparency of the Universe to the propagation
of high energy gamma radiation and from the stability of pions in air showers.
These three paradoxes can be explained through deformations of the relativistic
dispersion relation. Theoretical ideas aimed to understand how Lorentz symmetry
may be broken and phenomenologically interesting deformations of the
relativistic dispersion relation may arise are briefly discussed.",0301191v1
2003-06-13,Vector Component of Confinement Force and P-Wave Spectrum of D mesons,"The mass spectrum and the pionic decay widths of the P-wave $D$ mesons are
studied using the Dirac equation for the light quark. Our aim is to determine
the Lorentz property of the confinement force. We find that the Lorentz scalar
confinement is consistent with the mass spectrum, while a significant mixture
of the Lorentz vector confinement is necessary to explain the decay widths.",0306111v1
2003-07-16,Neutrino mixing and Lorentz invariance,"We use previous work on the Hilbert space for mixed fields to derive deformed
dispersion relations for neutrino flavor states. We then discuss how these
dispersion relations may be incorporated into frameworks encoding the breakdown
of Lorentz invariance. We consider non-linear relativity schemes (of which
doubly special relativity is an example), and also frameworks allowing for the
existence of a preferred frame. In both cases we derive expressions for the
spectrum and end-point of beta decay, which may be used as an experimental
probe of the peculiar way in which neutrinos experience Lorentz invariance.",0307205v1
2003-08-27,Lorentz and CPT Tests in Matter and Antimatter,"A review of recent theoretical work investigating tests of Lorentz and CPT
symmetry in atomic and particle systems is presented. A variety of tests in
matter and antimatter are discussed, including measurements of anomalous
magnetic moments in Penning traps, comparisons of atomic-clock transitions,
high-precision spectroscopic measurements of hydrogen and antihydrogen,
experiments with muons, experiments with mesons, and tests of Lorentz symmetry
with a spin-polarized torsion pendulum.",0308281v2
2003-09-14,"The Lorentz and CPT violating effects on H^0\to f^+ f^- (ZZ, W^+ W^-) decays","We study the Lorentz and CPT violating effects on the ratio
\frac{BR_{LorVio}}{BR_{SM}}, where BR_{LorVio} (BR_{SM}) is the branching
ratios coming from the Lorentz violating effects (the SM), for the decays
H^0\to f^+ f^- (f= quarks and charged leptons) and H^0\to ZZ (W^+ W^-). We
observe that these new effects are too small to be detected, especially for f^+
f^- output, since the corresponding coefficients are highly suppressed at the
low energy scale.",0309154v1
2004-02-12,Lorentz-violating dispersion relations and threshold analyses,"Remnant low-energy effects of Planck-scale Lorentz breaking in candidate
fundamental theories typically include modified one-particle dispersion
relations. Theoretical constraints on such modifications are discussed leading
to the exclusion of a variety of previously considered Lorentz-violating
parameters. In particular, the fundamental principle of coordinate
independence, the role of an effective dynamical framework, and the conditions
of positivity and causality are investigated.",0402133v1
2004-05-26,Parton Model in Lorentz Invariant Non-Commutative Space,"We consider the Lorentz invariant non-commutative QED and complete the
Feynman rules for the theory up to the order $\theta^2$. In the Lorentz
invariant version of the non-commutative QED the particles with fractional
charges can be also considered. We show that in the parton model, even at the
lowest order, the Bjorken scaling violates as $\sim\theta^2Q^4$.",0405270v2
2004-06-17,Lorentz Contraction of Bound States in 1+1 Dimensional Gauge Theory,"We consider the Lorentz contraction of a fermion-antifermion bound state in
1+1 dimensional QED. In 1+1 dimensions the absence of physical, propagating
photons allows us to explicitly solve the weak coupling limit \alpha << m^2 of
the Bethe-Salpeter bound state equation in any Lorentz frame. In a time-ordered
formalism it is seen that all pair production is suppressed in this limit. The
wave function is shown to contract while the mass spectrum is invariant under
boosts.",0406186v2
2004-06-25,On the validity of Lorentz invariance relations between parton distributions,"Lorentz invariance relations connecting twist-3 parton distributions with
transverse momentum dependent twist-2 distributions have been proposed
previously. These relations can be extracted from a covariant decomposition of
the quark-quark correlator. It is argued, however, that the derivation of the
Lorentz invariance relations fails if the path-ordered exponential is taken
into account in the correlator. The model independent analysis is supplemented
by an explicit calculation of the corresponding parton distributions in
perturbative QCD with a quark target, and in a simple spectator model. We also
clarify the status of a specific calculation of time-reversal even parton
distributions in light-cone gauge.",0406289v1
2004-07-30,Violation of Lorentz invariance and dynamical effects in high energy gamma rays,"The relation between the violation of Lorentz invariance and the dynamical
effects in high energy gamma rays production is discussed. By using the
framework of noncommutative classical electrodynamics, it is shown that full
dynamical calculations are required to put bounds on the Lorentz violating
scale by the phenomenological analysis of these processes as, for example, the
synchrotron radiation from the CRAB nebula. It is observed that an improvement
of the present bound on the scale of noncommutativity can be obtained only by
astrophysical observations of gamma ray spectra in strong magnetic fields such
as pulsars.",0407363v1
2004-09-24,Global Defects In Theories With Lorentz Symmetry Violation,"We study global topological defects in the Jacobson-Corley model which breaks
Lorentz symmetry and involves up to fourth order derivatives. There is a window
in the parameter space in which no solution exists. Otherwise, different
profiles are allowed for the same values of the parameters. For a scale of
  Lorentz violation much higher than the scale of gauge symmetry breaking, the
energy densities are higher, of the same order or smaller than in the usual
case for domain walls, cosmic strings and hedgehogs respectively. Possible
cosmological implications are suggested.",0409285v2
2004-12-02,Radiation in Lorentz violating electrodynamics,"Synchrotron radiation is analyzed in the classical effective Lorentz
invariance violating model of Myers-Pospelov. Within the full far-field
approximation we compute the electric and magnetic fields, the angular
distribution of the power spectrum and the total emitted power in the m-th
harmonic, as well as the polarization. We find the appearance of rather
unexpected and large amplifying factors, which go together with the otherwise
negligible naive expansion parameter. This opens up the possibility of further
exploring Lorentz invariance violations by synchrotron radiation measurements
in astrophysical sources where these amplifying factors are important.",0412023v1
2005-02-15,Lorentz violation of the standard model,"Though the standard model of electroweak interactions is commonly believed to
provide a successful unification of electromagnetic and weak interactions, the
approximation in the massless limit and the assumption of massless fermion in
this model should be investigated further with rigorousness. Here it will be
shown that this approximation violates Lorentz invariance and it is still
necessary even with the assumption of a massless fermion and the Higgs
mechanism. We conclude that the unification of electroweak interactions is only
valid with the assumption of Lorentz violation.",0502142v1
2005-04-26,Laboratory bounds on Lorentz symmetry violation in low energy neutrino physics,"Quantitative bounds on Lorentz symmetry violation in the neutrino sector have
been obtained by analyzing existing laboratory data on neutron $\beta$ decay
and pion leptonic decays. In particular some parameters appearing in the
energy-momentum dispersion relations for $\nu_e$ and $\nu_\mu$ have been
constrained in two typical cases arising in many models accounting for Lorentz
violation.",0504245v3
2005-05-14,Probing Lorentz violation with Doppler-shift experiments,"We analyze Doppler-effect experiments in terms of a general framework for
violations of Lorentz symmetry: the Standard-Model Extension. These experiments
are found to be sensitive to heretofore unprobed combinations of
Lorentz-violation coefficients associated with protons and electrons. New
bounds at the level of $10^{-11}$ and $10^{-8}$ for proton coefficients and
$10^{-2}$ for electron coefficients emerge from a recent experiment.",0505130v2
2005-08-29,Baryon asymmetry in the Universe resulting from Lorentz violation,"We analyze the phenomenological consequences of a Lorentz violating
energy-momentum dispersion relation in order to give a simple explanation for
the baryon asymmetry in the Universe. By assuming very few hypotheses, we
propose a straightforward mechanism for generating the observed
matter-antimatter asymmetry which entails a Lorentz-breakdown energy scale of
the order of the Greisen-Zatsepin-Kuzmin cut-off.",0508298v3
2005-10-07,QCD string and the Lorentz nature of confinement,"We address the question of the Lorentz nature of the effective long-range
interquark interaction generated by the QCD string with quarks at the ends.
Studying the Dyson-Schwinger equation for a heavy-light quark-antiquark system,
we demonstrate explicitly how a Lorentz-scalar interaction appears in the
Diraclike equation for the light quark, as a consequence of chiral symmetry
breaking. We argue that the effective interquark interaction in the Hamiltonian
of the QCD string with quarks at the ends stems from this effective scalar
interaction.",0510092v1
2006-08-08,Limits on Neutron Lorentz Violation from Pulsar Timing,"Pulsars are the most accurate naturally occurring clocks, and data about them
can be used to set bounds on neutron-sector Lorentz violations. If SO(3)
rotation symmetry is completely broken for neutrons, then pulsars' rotation
speeds will vary periodically. Pulsar timing data limits the relevant
Lorentz-violating coefficients to be smaller than 1.7 x 10^(-8) at at least 90%
confidence.",0608094v2
2006-10-06,CPT-odd Leptogenesis,"We calculate the baryon asymmetry of the Universe resulting from the
combination of higher-dimensional Lorentz-noninvariant CPT-odd operators and
dimension five operators that induce the majorana mass for neutrinos. The
strength of CPT-violating dimension five operators capable of producing the
observed value of baryon abundance is directly related to neutrino masses and
found to be in the trans-Planckian range 10^{-24}-10^{-22} GeV^{-1}.
Confronting it with observational tests of Lorentz symmetry, we find that this
range of Lorentz/CPT violation is strongly disfavored by the combination of the
low-energy constraints and astrophysical data.",0610070v2
2006-12-29,Cavity tests of parity-odd Lorentz violations in electrodynamics,"Electromagnetic resonant cavities form the basis for a number modern tests of
Lorentz invariance. The geometry of most of these experiments implies
unsuppressed sensitivities to parity-even Lorentz violations only. Parity-odd
violations typically enter through suppressed boost effects, causing a
reduction in sensitivity by roughly four orders of magnitude. Here we discuss
possible techniques for achieving unsuppressed sensitivities to parity-odd
violations by using asymmetric resonators.",0612372v1
2007-03-29,Lorentz Conserving Noncommutative Standard Model,"We consider Lorentz conserving noncommutative field theory to construct the
Lorentz conserving noncommutative standard model based on the gauge group
$SU(3)\times SU(2)\times U(1)$. We obtain the enveloping algebra-valued of
Higgs field up to the second order of the noncommutativity parameter
$\th_{\mu\nu}$. We derive the action at the leading order and find new vertices
which are absent in the ordinary Standard Model as well as the minimal
noncommutative standard model. We briefly study the phenomenological aspects of
the model.",0703313v2
1992-07-21,A Quantum Anomaly For Rigid Particles,"Canonical quantisation of rigid particles is considered paying special
attention to the restriction on phase space due to causal propagation. A mixed
Lorentz-gravitational anomaly is found in the commutator of Lorentz boosts with
world-line reparametrisations. The subspace of gauge invariant physical states
is therefore not invariant under Lorentz transformations. The analysis applies
for an arbitrary extrinsic curvature dependence with the exception of only one
case to be studied separately. Consequences for rigid strings are also
discussed.",9207068v2
1993-08-09,Spontaneously Broken Lorentz Invariance in Three-Dimensional Gauge Theories,"In a wide class of three-dimensional Abelian gauge theories with a bare
Chern-Simons term, the Lorentz invariance is spontaneously broken by dynamical
generation of a non-vanishing magnetic field. A detailed computation of an
energy density of the true vacuum is given. The originally massive photon
becomes massless, fulfilling the role of a Nambu-Goldstone boson associated
with the spontaneous breaking of the Lorentz invariance.",9308045v1
1995-05-18,Spontaneous Magnetization in Lorentz Invariant Theories,"In a class of three-dimensional Abelian gauge theories with both light and
heavy fermions, heavy chiral fermions can trigger dynamical generation of a
magnetic field, leading to the spontaneous breaking of the Lorentz invaiance.
Finite masses of light fermions tend to restore the Lorentz invariance.",9505113v2
1996-12-17,Self-duality in Generalized Lorentz Superspaces,"We extend the notion of self-duality to spaces built from a set of
representations of the Lorentz group with bosonic or fermionic behaviour, not
having the traditional spin-one upper-bound of super Minkowski space. The
generalized derivative vector fields on such superspaces are assumed to form a
superalgebra. Introducing corresponding gauge potentials and hence covariant
derivatives and curvatures, we define generalized self-duality as the Lorentz
covariant vanishing of certain irreducible parts of the curvatures.",9612176v1
1997-06-04,On a Lorentz covariant matrix regularization of membrane theories,"A Lorentz covariant matrix regularization of membrane thories is studied.It
is shown that the action for a bosonic membrane can be defined by matrix
regularization in a Lorentz covariant manner. The generator of area preserving
diffeomorphism can also be consistently defined by matrix regularization, and
we can make the area preserving gauge symmetry manifest. However, the
reparametrization BRST charge explicitly depends on a specific basis set
introduced to define the matrix regularization. We also briefly comment on an
extension of the present formulation to a supermembrane.",9706027v1
1998-10-14,How `Complex' is the Dirac Equation?,"A representation of the Lorentz group is given in terms of 4 X 4 matrices
defined over a simple non-division algebra. The transformation properties of
the corresponding four component spinor are studied, and shown to be equivalent
to the transformation properties of the usual complex Dirac spinor. As an
application, we show that there exists an algebra of automorphisms of the
complex Dirac spinor that leave the transformation properties of its eight real
components invariant under any given Lorentz transformation. Interestingly, the
representation of the Lorentz group presented here has a natural embedding in
SO(3,3) instead of the conformal symmetry SO(2,4).",9810093v1
1998-12-03,Hyperbolic Numbers and the Dirac Spinor,"A representation of the Lorentz group is given in terms of 4 X 4 matrices
defined over the hyperbolic number system. The transformation properties of the
corresponding four component spinor are studied, and shown to be equivalent to
the transformation properties of the complex Dirac spinor. As an application,
we show that there exists an algebra of automorphisms of the complex Dirac
spinor that leaves the transformation properties of its eight real components
invariant under any given Lorentz transformation. Interestingly, the
representation of the Lorentz algebra presented here is naturally embedded in
the Lie algebra of a group isomorphic to SO(3,3;R) instead of the conformal
group SO(2,4;R).",9812036v1
1999-06-01,String theory in Lorentz-invariant light cone gauge,"Quantization of 4-dimensional Nambu-Goto theory of open string in light cone
gauge, related in Lorentz-invariant way with the world sheet, is performed.
Obtained quantum theory has no anomalies in Lorentz group. Determined spin-mass
spectra of the theory have Regge-like behavior and do not contain the tachyon.
Vertex operators of interaction theory, acting in the physical subspace, are
constructed.",9906003v1
2000-11-17,Nonlinear Realization of Lorentz Symmetry,"We explore a nonlinear realization of the (2+1)-dimensional Lorentz symmetry
with a constant vacuum expectation value of the second rank anti-symmetric
tensor field. By means of the nonlinear realization, we obtain the low-energy
effective action of the Nambu-Goldstone bosons for the spontaneous Lorentz
symmetry breaking.",0011158v2
2001-01-31,Spontaneous Lorentz Symmetry Breaking by Anti-Symmetric Tensor Field,"We study the spontaneous Lorentz symmetry breaking in a field theoretical
model in (2+1)-dimension, inspired by string theory. This model is a gauge
theory of an anti-symmetric tensor field and a vector field (photon). The
Nambu-Goldstone (NG) boson for the spontaneous Lorentz symmetry breaking is
identified with the unphysical massless photon in the covariant quantization.
We also discuss an analogue of the equivalence theorem between the amplitudes
for emission or absorption of the physical massive anti-symmetric tensor field
and those of the unphysical massless photon. The low-energy effective action of
the NG-boson is also discussed.",0101222v1
2001-02-05,Physical (ir)relevance of ambiguities to Lorentz and CPT violation in QED,"We discuss the regularization and renormalization of QED with Lorentz and CPT
violation, and argue that the coefficient of the Chern-Simons term is an
independent parameter not determined by gauge invariance. We also study these
issues in a model with spontaneous breaking of Lorentz and CPT symmetries and
find an explicit relation with the ABJ anomaly. This explains the observed
convergence of the induced Chern-Simons term.",0102021v2
2001-05-09,Noncommutative Field Theory and Lorentz Violation,"The role of Lorentz symmetry in noncommutative field theory is considered.
Any realistic noncommutative theory is found to be physically equivalent to a
subset of a general Lorentz-violating standard-model extension involving
ordinary fields. Some theoretical consequences are discussed. Existing
experiments bound the scale of the noncommutativity parameter to (10 TeV)^{-2}.",0105082v1
2001-05-15,Lorentz Invariance of the Pure Spinor BRST Cohomology for the Superstring,"In a previous paper, the BRST cohomology in the pure spinor formalism of the
superstring was shown to coincide with the light-cone Green-Schwarz spectrum by
using an SO(8) parameterization of the pure spinor. In this paper, the SO(9,1)
Lorentz generators are explicitly constructed using this SO(8)
parameterization, proving the Lorentz invariance of the pure spinor BRST
cohomology.",0105149v1
2001-11-13,One-Loop Renormalization of Lorentz-Violating Electrodynamics,"We show that the general Lorentz- and CPT-violating extension of quantum
electrodynamics is one-loop renormalizable. The one-loop Lorentz-violating beta
functions are obtained, and the running of the coefficients for Lorentz and CPT
violation is determined. Some implications for theory and experiment are
discussed.",0111123v1
2002-06-18,A Note on Lie-Lorentz Derivatives,"The definition of ``Lie derivative'' of spinors with respect to Killing
vectors is extended to all kinds of Lorentz tensors. This Lie-Lorentz
derivative appears naturally in the commutator of two supersymmetry
transformations generated by Killing spinors and vanishes for Vielbeins. It can
be identified as the generator of the action of isometries on supergravity
fields and its use for the calculation of supersymmetry algebras is revised and
extended.",0206159v2
2002-11-18,Spontaneous Violation of Lorentz Invariance and Ultra-High Energy Cosmic Rays,"We propose that local Lorentz invariance is spontaneously violated at high
energies, due to a nonvanishing vacuum expectation value of a vector field
\phi^\mu, as a possible explanation of the observation of ultra-high energy
cosmic rays with an energy above the GZK cutoff. Certain consequences of
spontaneous breaking of Lorentz invariance in cosmology are discussed.",0211167v2
2003-01-25,String theory in Lorentz-invariant light cone gauge - II,"We perform a quantization of 4-dimensional Nambu-Goto theory of open string
in light cone gauge, related in Lorentz-invariant way with the world sheet.
This allows to obtain a quantum theory without anomalies in Lorentz group. We
consider a special type of gauge fixing conditions, imposed in oscillator
sector of the theory, which lead to a relatively simple Hamiltonian mechanics,
convenient for canonical quantization. We discuss the algebraic and geometric
properties of this mechanics and determine its mass spectrum for the states of
spin singlet S=0.",0301204v2
2003-03-13,Lorentz and CPT symmetries in commutative and noncommutative spacetime,"We investigate the fermionic sector of a given theory, in which massive and
charged Dirac fermions interact with an Abelian gauge field, including a non
standard contribution that violates both Lorentz and CPT symmetries. We offer
an explicit calculation in which the radiative corrections due to the fermions
seem to generate a Chern-Simons-like effective action. Our results are obtained
under the general guidance of dimensional regularization, and they show that
there is no room for Lorentz and CPT violation in both commutative and
noncommutative spacetime.",0303122v1
2003-06-04,Chiral QED in Terms of Chiral Boson with a Generalized Fadeevian Regularization,"Chiral QED with a generalized Fadeevian regularization is considered.
Imposing a chiral constraint a gauged version of Floranini-Jackiw lagrangian is
constructed. The imposition of the chiral constarint has spoiled t he
manifestly Lorentz covariance of the theory. The phase space structure for this
theory has been det ermined. It is found that spectrum changes drastically but
it is Lorentz invariant. Chiral fermion di sappears from the spectra and the
photon anquire mass as well. Poincare algebra has been calculated to show
physicial Lorentz invariance explicitely.",0306037v1
2003-09-16,Lorentz Invariance And Unitarity Problem In Non-Commutative Field Theory,"It is shown that the one-loop two-point amplitude in {\it Lorentz-invariant}
non-commutative (NC) $\phi^3$ theory is finite after subtraction in the
commutative limit and satisfies the usual cutting rule, thereby eliminating the
unitarity problem in Lorentz-non-invariant NC field theory in the approximation
considered.",0309155v3
2003-09-16,Discrete Symmetries In Lorentz-Invariant Non-Commutative QED,"It is pointed out that the usual $\theta$-algebra assumed for non-commuting
coordinates is not $P$- and $T$-invariant, unless one {\it formally} transforms
the non-commutativity parameter $\theta^{\mu\nu}$ in an appropriate way. On the
other hand, the Lorentz-covariant DFR algebra, which `relativitizes' the
$\theta$-algebra by replacing $\theta^{\mu\nu}$ with a second-rank
antisymmetric tensor operator $\htheta^{\mu\nu}$, is $C$-, $ P$- and
$T$-invariant. It is then proved that $C, P$ and $T$ are separately conserved
in Lorentz-invariant Non-Commutative QED.",0309159v2
2003-10-10,A Completely Invariant SUSY Transform of Supersymmetric QED,"We study the SUSY breaking of the covariant gauge-fixing term in SUSY QED and
observe that this corresponds to a breaking of the Lorentz gauge condition by
SUSY. Reasoning by analogy with SUSY's violation of the Wess-Zumino gauge, we
argue that the SUSY transformation, already modified to preserve Wess-Zumino
gauge, should be further modified by another gauge transformation which
restores the Lorentz gauge condition. We derive this modification and use the
resulting transformation to derive a Ward identitiy relating the photon and
photino propagators without using ghost fields. Our transformation also
fulfills the SUSY algebra, modulo terms that vanish in Lorentz gauge.",0310098v1
2003-12-05,Yang-Mills Instantons with Lorentz Violation,"An analysis is performed of instanton configurations in pure Euclidean
Yang-Mills theory containing small Lorentz-violating perturbations that
maintain gauge invariance. Conventional topological arguments are used to show
that the general classification of instanton solutions involving the
topological charge is the same as in the standard case. Explicit solutions are
constructed for general gauge invariant corrections to the action that are
quadratic in the curvature. The value of the action is found to be unperturbed
to lowest order in the Lorentz-violating parameters.",0312058v1
2004-02-21,Concerning the generalized Lorentz symmetry and the generalization of the Dirac equation,"The work is devoted to the generalization of the Dirac equation for a flat
locally anisotropic, i.e., Finslerian space-time. At first we reproduce the
corresponding metric and a group of the generalized Lorentz transformations,
which has the meaning of the relativistic symmetry group of such event space.
Next, proceeding from the requirement of the generalized Lorentz invariance we
find a generalized Dirac equation in its explicit form. An exact solution of
the nonlinear generalized Dirac equation is also presented.",0402172v1
2004-07-29,Internal Structure of Ultra-High Energy Particles with Lorentz Symmetry Violation at the Planck Scale,"Assuming the existence of a local vacuum rest frame (LVRF), and using
suitable algebraic tranformations, the internal structure of ultra-high energy
particles (UHEPs) is studied in the presence of Lorentz symmetry violation
(LSV) at the Planck scale. Violations of the standard Lorentz contraction and
time dilation formulae are made explicit. Dynamics in the rest frame of a UHEP
is worked out and discussed. Phenomenological implications for ultra-high
energy cosmic rays (UHECR), including possible violations of the
Greisen-Zatsepin-Kuzmin GZK) cutoff, are studied for several LSV models.",0407254v1
2004-10-29,The N = 2 and N = 4 Supersymmetric Extensions of the Lorentz- and CPT-Violating Term in Abelian Gauge Theories,"In this work, we propose the N=2 and N=4 supersymmetric extensions of the
Lorentz-breaking Abelian Chern-Simons term. We formulate the question of the
Lorentz violation in 6 and 10 dimensions to obtain the bosonic sectors of N=2,
and N=4, supersymmetries, respectively. From this, we carry out an analysis in
N=1, D=4 superspace and, in terms of N=1, superfields, we are able to write
down the N=2 and N=4 supersymmetric versions of the Lorentz-violating action
term.",0410287v1
2004-11-12,Violation of Remaining Lorentz Symmetry in the Approach of Time-Ordered Perturbation Theory to Space-Time Noncommutativity,"We study remaining Lorentz symmetry, i.e. Lorentz transformations which leave
the noncommutativity parameter $\theta^{\mu\nu}$ invariant, within the approach
of time-ordered perturbation theory (TOPT) to space-time noncommutative
theories. Their violation is shown in a simple scattering process. We argue
that this results from the non-covariant transformation properties of the phase
factors appearing in TOPT.",0411127v2
2005-06-08,Ultra-large distance modification of gravity from Lorentz symmetry breaking at the Planck scale,"We present an extension of the Randall--Sundrum model in which, due to
spontaneous Lorentz symmetry breaking, graviton mixes with bulk vector fields
and becomes quasilocalized. The masses of KK modes comprising the
four-dimensional graviton are naturally exponentially small. This allows to
push the Lorentz breaking scale to as high as a few tenth of the Planck mass.
The model does not contain ghosts or tachyons and does not exhibit the van
Dam--Veltman--Zakharov discontinuity. The gravitational attraction between
static point masses becomes gradually weaker with increasing of separation and
gets replaced by repulsion (antigravity) at exponentially large distances.",0506067v1
2005-06-13,Lorentz-Covariant Quantization of Massive Non-Abelian Gauge Fields in The Hamiltonian Path-Integral Formalism,"The massive non-Abelian gauge fields are quantized Lorentz-covariantly in the
Hamiltonian path-integral formalism. In the quantization, the Lorentz
condition, as a necessary constraint, is introduced initially and incorporated
into the massive Yang-Mills Lagrangian by the Lagrange multiplier method so as
to make each temporal component of a vector potential to have a canonically
conjugate counterpart. The result of this quantization is confirmed by the
quantization performed in the Lagrangian path-integral formalism by applying
the Lagrange multiplier method which is shown to be equivalent to the
Faddeev-Popov approach.",0506101v1
2005-10-13,Lorentz symmetry breaking in the noncommutative Wess-Zumino model: One loop corrections,"In this paper we deal with the issue of Lorentz symmetry breaking in quantum
field theories formulated in a non-commutative space-time. We show that, unlike
in some recente analysis of quantum gravity effects, supersymmetry does not
protect the theory from the large Lorentz violating effects arising from the
loop corrections. We take advantage of the non-commutative Wess-Zumino model to
illustrate this point.",0510108v3
2005-11-21,Quasi-exact solvability of Dirac equation with Lorentz scalar potential,"We consider exact/quasi-exact solvability of Dirac equation with a Lorentz
scalar potential based on factorizability of the equation. Exactly solvable and
$sl(2)$-based quasi-exactly solvable potentials are discussed separately in
Cartesian coordinates for a pure Lorentz potential depending only on one
spatial dimension, and in spherical coordinates in the presence of a Dirac
monopole.",0511204v1
2006-02-10,Matter waves in terms of the unitary representations of the Lorentz group,"In a generalized Heisenberg/Schroedinger picture, the unitary representations
of the Lorentz group may, for a massive relativistic particle, be used to
attribute to waves an extra wavelength that is longer than the de Broglie
wavelength. Propagators are defined as spacetime transitions between states
with different eigenvalues of the first or the second Casimir operator of the
Lorentz algebra.",0602104v3
2006-02-17,Electrostatic and Magnetostatic Solutions in a Lorentz-Violating Electrodynamics Model,"We propose an effective Lorentz violating electrodynamics model via static de
Sitter metric which is deviated from Minkowski metric by a minuscule amount
depending on the cosmological constant. We obtain the electromagnetic field
equations via the vierbein decomposition of the tensors. In addition, as an
application of the electromagnetic field equations obtained, we get the
solutions of electrostatic field and magnetostatic field due to a point charge
and a circle current respectively and discussed the implication of the effect
of Lorentz violation in our electromagnetic theory.",0602167v2
2006-07-19,Nambu-Goldstone Modes in Gravitational Theories with Spontaneous Lorentz Breaking,"Spontaneous breaking of Lorentz symmetry has been suggested as a possible
mechanism that might occur in the context of a fundamental Planck-scale theory,
such as string theory or a quantum theory of gravity. However, if Lorentz
symmetry is spontaneously broken, two sets of questions immediately arise: what
is the fate of the Nambu-Goldstone modes, and can a Higgs mechanism occur? A
brief summary of some recent work looking at these questions is presented here.",0607127v2
2006-09-04,Vacuum Cerenkov Radiation in Lorentz-Violating Theories Without CPT Violation,"In theories with broken Lorentz symmetry, Cerenkov radiation may be possible
even in vacuum. We analyze the Cerenkov emissions that are associated with the
least constrained Lorentz-violating modifications of the photon sector,
calculating the threshold energy, the frequency spectrum, and the shape of the
Mach cone. In order to obtain sensible results for the total power emitted, we
must make use of information contained within the theory which indicates at
what scale new physics must enter.",0609030v1
2001-10-17,Unitary Representations of Quantum Lorentz Group and Quantum Relativistic Toda Chain,"The aim of this paper is to give a group theoretical interpretation of the
three types of Bessel-Jackson functions. We consider a family of quantum
Lorentz groups and a family of quantum Lobachevsky spaces. For three members of
quantum Lobachevsky spaces the Casimir operators give rise to the two-body
relativistic open Toda lattice Hamiltonians. Their eigen-functions are the
modified Bessel-Jackson functions of three types. We construct the principal
series of unitary irreducible representations of the quantum Lorentz groups.
Special matrix elements in the irreducible spaces are the
Bessel-Macdonald-Jackson functions. They are the wave functions of the two-body
relativistic open Toda lattice. We obtain integral representations for these
functions.",0110182v1
2003-09-09,Knot Theory With The Lorentz Group,"We analyse the perturbative expansion of the knot invariants defined from the
unitary representations of the Quantum Lorentz Group in two different ways,
namely using the Kontsevich Integral and weight systems, and the $R$-matrix in
the Quantum Lorentz Group defined by Buffenoir and Roche. The two formulations
are proved to be equivalent; and they both yield $C[[h]]$-valued knot
invariants related with the Melvin Morton expansion of the Coloured Jones
Polynomial.",0309162v4
2001-12-21,"Lorentz-covariant ultradistributions, hyperfunctions, and analytic functionals","We generalize the theory of Lorentz-covariant distributions to broader
classes of functionals including ultradistributions, hyperfunctions, and
analytic functionals with a tempered growth. We prove that Lorentz-covariant
functionals with essential singularities can be decomposed into polynomial
covariants and establish the possibility of the invariant decomposition of
their carrier cones. We describe the properties of odd highly singular
generalized functions. These results are used to investigate the vacuum
expectation values of nonlocal quantum fields with an arbitrary high-energy
behavior and to extend the spin--statistics theorem to nonlocal field theory.",0112052v1
2002-05-09,Hyperspherical Functions and Linear Representations of the Lorentz Group,"A double covering of the proper orthochronous Lorentz group is understood as
a complexification of the special unimodular group of second order (a double
covering of the 3-dimensional rotation group). In virtue of such an
interpretation the matrix elements of finite-dimensional representations of the
Lorentz group are studied in terms of hyperspherical functions. Different forms
of the hyperspherical functions related to other special functions
(hypergeometric series, generalized spherical functions, Jacobi functions,
Appell functions) are considered. It is shown that there is a close
relationship between hyperspherical functions and physical fields defined
within $(j,0)\oplus(0,j)$ representation spaces. Recurrence relations between
hyperspherical functions are given.",0205013v1
2003-09-30,Group Structure of an Extended Lorentz Group,"In a previous paper we extended the Lorentz group to include a set of Dirac
boosts that give a direct correspondence with a set of generators which for
spin 1/2 systems are proportional to the Dirac matrices. The group is
particularly useful for developing general linear wave equations beyond spin
1/2 systems. In this paper we develop explicit group properties of this
extended Lorentz group to obtain group parameters that will be useful for
physical calculations for systems which might manifest the group properties.
This group is a subgroup of an extended Poincare group, whose structure will be
developed in a subsequent paper.",0309060v1
2005-05-03,Comment on ``The Avez-Seifert theorem for the relativistic Lorentz force equation'' and other related works,"There exist several approaches that investigate the connectedness of
spacetime events through solutions of the Lorentz force equation. These
approaches separate into three categories, that consider different equations.
We clarify the physical meaning of each equation showing that only one method
is based on the Lorentz force equation. The other two approaches lead
respectively to a less restrictive equation that defines an electromagnetic
flow on the cotangent fiber bundle, or to an unphysical constraint between
charge-to-mass ratio and proper length of the solution. We outline the physical
meaning of each approach studying the variational formulations and clarifying
the results obtained in the explored directions.",0505006v1
2005-12-21,"Spin, Statistics, and Reflections, II. Lorentz Invariance","The analysis of the relation between modular P$_1$CT-symmetry -- a
consequence of the Unruh effect -- and Pauli's spin-statistics relation is
continued. The result in the predecessor to this article is extended to the
Lorentz symmetric situation. A model $\G_L$ of the universal covering
$\widetilde{L_+^\uparrow}\cong SL(2,\complex)$ of the restricted Lorentz group
$L_+^\uparrow$ is modelled as a reflection group at the classical level. Based
on this picture, a representation of $\G_L$ is constructed from pairs of
modular P$_1$CT-conjugations, and this representation can easily be verified to
satisfy the spin-statistics relation.",0512068v1
2000-12-28,Anomalous Diffusion and Quantum Interference Effect in Nano-scale Periodic Lorentz Gas,"Recent advances in submicrometer technology have made it possible to confine
the two-dimensional electron gas into high-mobility semi-conductor
heterostructures. Such structure with a lattice of electron-depleted circular
obstacles are called quantum antidot lattices, or quantum Lorentz gas systems.
By using the semiclassical scattering theory, we show that quantum interference
in finite-size open Lorentz gas systems is expected to reflect the difference
between normal and anomalous diffusions, i.e., L\'evy flights.",0012062v1
2000-04-26,Van der Waals Excluded Volume Model for Lorentz Contracted Rigid Spheres,"Conventional cluster and virial expansions are generalized to momentum
dependent inter-particle potentials. The model with Lorentz contracted hard
core potentials is considered, e.g. as hadron gas model. A Van der Waals-type
model with a temperature dependent excluded volume is derived. Lorentz
contraction effects at given temperature are stronger for light particles and
make their effective excluded volume smaller than that of heavy ones.",0004061v1
2002-04-15,Hyperbolic triangle in the special theory of relativity,"The vector form of a Lorentz transformation which is separated with time and
space parts is studied. It is necessary to introduce a new definition of the
relative velocity in this transformation, which plays an important role for the
calculations of various invariant physical quantities. The Lorentz
transformation expressed with this vector form is geometrically well
interpreted in a hyperbolic space. It is shown that the Lorentz transformation
can be interpreted as the law of cosines and sines for a hyperbolic triangle in
hyperbolic trigonometry. So the triangle made by the two origins of inertial
frames and a moving particle has the angles whose sum is less than $180 ^o$.",0204037v1
2005-06-29,"Lorentz contraction, geometry and range in antiproton-proton annihilation into two pions","We present a geometric interpretation of the so-called annihilation range in
reactions of the type $\bar pp \to$ {\em two light mesons} based upon Lorentz
effects in the highly relativistic final states
($\gamma=E_{\mathrm{cm}}/2mc^2\simeq 6.8-8.0$). Lorentz-boosted meson wave
functions, within the framework of the constituent quark model, result in a
richer angular dependence of the annihilation amplitudes and thus in higher
partial wave contributions ($J>1$) than usually obtained. This approach sheds
some light on what could be a ""{\em short}"" annihilation range and how it is
influenced by the angular distribution of the final states.",0506084v1
1997-12-31,"Lorentz symmetry violation at Planck scale, cosmology and superluminal particles","Although Lorentz symmetry has been tested at low energy with extremely good
accuracy, its validity at very high energy is much less well established. If
Lorentz symmetry violation (LSV) is energy-dependent (e.g. $\propto E^2$), it
can be of order 1 at Planck scale and undetectable at GeV scale or below.
Similarly, superluminal particles with positive mass and energy (superbradyons)
can exist and be the ultimate building blocks of matter. We discuss a few
cosmological consequences of such a scenario, as well as possible experimental
tests.",9712056v2
1999-11-14,The critical manifold of the Lorentz-Dirac equation,"We investigate the solutions to the Lorentz-Dirac equation and show that its
solution flow has a structure identical to the one of renormalization group
flows in critical phenomena. The physical solutions of the Lorentz-Dirac
equation lie on the critical surface. The critical surface is repelling, i.e.
any slight deviation from it is amplified and as a result the solution runs
away to infinity. On the other hand, Dirac's asymptotic condition (acceleration
vanishes for long times) forces the solution to be on the critical manifold.
The critical surface can be determined perturbatively. Thereby one obtains an
effective second order equation, which we apply to various cases, in particular
to the motion of an electron in a Penning trap.",9911027v1
2000-08-28,Limit on Lorentz and CPT Violation of the Proton Using a Hydrogen Maser,"We present a new measurement constraining Lorentz and CPT violation of the
proton using a hydrogen maser double resonance technique. A search for hydrogen
Zeeman frequency variations with a period of the sidereal day (23.93 h) sets a
clean limit on violation of Lorentz and CPT symmetry of the proton at the
10^{-27} GeV level.",0008230v1
2001-10-22,Multiple Fiztgerald-Lorentz contractions,"In a recent paper, Harada and Sachs suggested that the Fitzgerald-Lorentz
contraction does not refer to a physical contraction but can perhaps best be
seen as a 'currency conversion'. In the present paper, this view is inspected,
and it is found, beyond the immediate frame of the interpretation, that the
Fitzgerald-Lorentz contraction leads to a contradiction in a system of more
than two observers. A possible physical system in which this can occur is a
relativistic (ideal) gas or fluid.",0110058v1
2002-03-09,Reinterpretation of Lorentz Transformation and resolution of Special Relativity's paradoxes,"Lorentz Transformation is reinterpreted. It is shown that by admitting the
existence of a frame of reference with synchronized clocks, we conclude that
any other frame of reference that moves related to the first has desynchronized
clocks. From this conclusion we will arrive at a new expression to relate the
time of different frames of reference. We also arrive at a new expression to
relate the contraction of different frames. We will show that if the maximum
speed on a frame with synchronized clocks is the speed of light, then the speed
of light varies accordingly to the velocity of the frame of reference. The new
interpretation of Lorentz Transformation explains and solves Relativity's
paradoxes.",0203025v1
2003-07-01,On the Solutions of the Lorentz-Dirac Equation,"We discuss the unstable character of the solutions of the Lorentz-Dirac
equation and stress the need of methods like order reduction to derive a
physically acceptable equation of motion. The discussion is illustrated with
the paradigmatic example of the non-relativistic harmonic oscillator with
radiation reaction. We also illustrate removal of the noncasual
pre-acceleration with the introduction of a small correction in the
Lorentz-Dirac equation.",0307005v1
2003-07-22,"The Lorentz Group, a Galilean Approach","We present a pedagogical approach to the Lorentz group. We start by
introducing a compact notation to express the elements of the fundamental
representation of the rotations group.Lorentz coordinate transformations are
derived in a novel and compact form. We show how to make a Lorentz
transformation on the electromagnetic fields as well. A covariant
time-derivative is introduced in order to deal with non-inertial systems.
Examples of the usefulness of these results such as the rotating system and the
Thomas precession, are also presented",0307106v1
2003-11-24,Photon trajectories in incoherent atomic radiation trapping as Levy flights,"Photon trajectories in incoherent radiation trapping for Doppler, Lorentz and
Voigt line shapes under complete frequency redistribution are shown to be Levy
flights. The jump length (r) distributions display characteristic long tails.
For the Lorentz line shape, the asymptotic form is a strict power-law r^{-3/2}
while for Doppler the asymptotic is r^{-2} (ln r)^{-1/2}. For the Voigt
profile, the asymptotic form has always a Lorentz character, but the trajectory
is a self-affine fractal with two characteristic Hausdorff scaling exponents.",0311113v2
2004-03-04,Magneto-electro-optical properties of the quantum vacuum and Lorentz invariance,"We consider the magneto-electric optical properties of the quantum vacuum and
show that all the different phenomenona are related by Lorentz invariance. As a
model calculation we show how crossed fields properties can be calculated
starting from single field properties by using Lorentz transformations. Using
this method we have studied for the first time the case of a crossed static
magnetic field and electric field applied with one of these two fields parallel
to the direction of light propagation. We also show that parallel field
properties can be found using general symmetry properties.",0403036v1
2004-11-12,Lorentz's electromagnetic mass: a clue for unification?,"We review in the present article the conjecture of electromagnetic mass by
Lorentz. The philosophical perspectives and historical accounts of this idea
are described, especially, in the light of Einstein's special relativistic
formula {E = mc^2}. It is shown that the Lorentz's electromagnetic mass model
has taken various shapes through its journey and the goal is not yet reached.",0411127v4
2005-12-20,Reexamination of Barnett's Experiment Based on the Modified Lorentz Force Law,"Barnett's experiment demonstrates that the induction on a stationary
cylindrical capacitor in the presence of a rotating magnet or solenoid is zero.
In this investigation, based on the modified Lorentz force law, which complies
with Galilean transformations and depends on relative velocities, the induction
on the capacitor is reexamined. When the rotating solenoid is long and the
capacitor is placed inside the solenoid, it is seen that the induction actually
vanishes as observed in Barnett's experiment. However, when the capacitor is
placed outside the solenoid or when the solenoid is short, it is shown that the
induction can departure from zero. This prediction provides a means to test the
validity of the modified Lorentz force law.",0512179v1
2007-02-22,A simple derivation of the Lorentz transformation and of the related velocity and acceleration formulae,"The Lorentz transformation is entirely derived from length contraction,
itself established through the known light-clock thought experiment . This
makes the derivation accessible to beginning students once Eintein's two
postulates have been admitted. The formula derived for the space part of the
general rotation-free Lorentz transformation is very compact and allows for an
easy derivation of the velocity and acceleration transformations. A possibly
new and very simple relation is found between proper acceleration and
acceleration in an inertial frame.",0702191v1
2000-12-22,Worldline Influence Functional: Abraham-Lorentz-Dirac-Langevin Equation from QED,"We present a stochastic theory of charges moving in an electromagnetic field
using nonequilibrium quantum field theory. We give a first principles'
derivation of the Abraham-Lorentz-Dirac-Langevin equation which depicts the
quantum expectation value for a particle's trajectory and its stochastic
fluctuations by combining the worldline path integral quantization with the
Feynman-Vernon influence functional or closed-time-path effective action
methods. At lowest order, the equations of motion are approximated by a
stochastic Lorentz-Dirac equation.",0012135v1
2003-01-07,"A note on the Lorentz force, magnetic charges and the Casimir effect","We show that in order to account for the repulsive Casimir effect in the
parallel plate geometry in terms of the quantum version of the Lorentz force,
virtual surface densities of magnetic charges and currents must be introduced.
The quantum version of the Lorentz force expressed in terms of the correlators
of the electric and magnetic fields for planar geometries yields then correctly
the Casimir pressure.",0301021v1
2006-05-11,On the Generator of Lorentz Boost,"Traditionally, the theory related to the spatial angular momentum has been
studied completely, while the investigation in the generator of Lorentz boost
is inadequate. In this paper we show that the generator of Lorentz boost has a
nontrivial physical significance, it endows a charged system with an electric
moment, and has an important significance for the electrical manipulations of
electron spin in spintronics. An alternative treatment and interpretation for
the traditional Darwin term and spin-orbit coupling are given.",0605101v4
2006-08-07,Lorentz transformations that entangle spins and entangle momenta,"Simple examples are presented of Lorentz transformations that entangle the
spins and momenta of two particles with positive mass and spin 1/2. They apply
to indistinguishable particles, produce maximal entanglement from finite
Lorentz transformations of states for finite momenta, and describe entanglement
of spins produced together with entanglement of momenta. From the entanglements
considered, no sum of entanglements is found to be unchanged.",0608061v2
2007-04-09,On the induction of the four-dimensional Lorentz-breaking non-Abelian Chern-Simons action,"A four-dimensional Lorentz-breaking non-Abelian Chern-Simons like action is
generated as a one-loop perturbative correction via an appropriate
Lorentz-breaking coupling of the non-Abelian gauge field to the spinor field.
This term is shown to be regularization dependent but nevertheless it can be
found unambiguously in different regularization schemes at zero and finite
temperature.",0704.1104v2
2007-05-08,Lorentz Space Estimates for the Ginzburg-Landau Energy,"In this paper we prove novel lower bounds for the Ginzburg-Landau energy with
or without magnetic field. These bounds rely on an improvement of the ""vortex
balls construction"" estimates by extracting a new positive term in the energy
lower bounds. This extra term can be conveniently estimated through a Lorentz
space norm, on which it thus provides an upper bound. The Lorentz space
$L^{2,\infty}$ we use is critical with respect to the expected vortex profiles
and can serve to estimate the total number of vortices and get improved
convergence results.",0705.1094v1
2007-07-16,Lorentz transformation by mimicking the Lorentz transformation,"We show that starting with the fact that special relativity theory is
concerned with a distortion of the observed length of a moving rod, without
mentioning if it is a ""contraction"" or ""dilation"", we can derive the Lorentz
transformations for the spacetime coordinates of the same event. This
derivation is based on expressing the length of the moving rod as a sum of
components with all the lengths involved in this summation being measured by
the observers of the same inertial reference frame.",0707.2338v3
2007-09-10,Microcausality in Curved Space-Time,"It is well known that in Lorentz invariant quantum field theories in flat
space the commutator of space-like separated local operators vanishes
(microcausality). We provide two different arguments showing that this is a
consequence of the causal structure of the classical theory, rather than of
Lorentz invariance. In particular, microcausality holds in arbitrary curved
space-times, where Lorentz invariance is explicitly broken by the background
metric. As illustrated by an explicit calculation on a cylinder this property
is rather non trivial at the level of Feynman diagrams.",0709.1483v1
2007-09-15,Testing Lorentz Symmetry with Gravity,"In this talk, results from the gravitational sector of the Standard-Model
Extension (SME) are discussed. The weak-field phenomenology of the resulting
modified gravitational field equations is explored. The application of the
results to a variety of modern gravity experiments, including lunar laser
ranging, Gravity Probe B, binary pulsars, and Earth-laboratory tests, shows
promising sensitivity to gravitational coefficients for Lorentz violation in
the SME.",0709.2447v1
2007-09-19,The ambiguity-free four-dimensional Lorentz-breaking Chern-Simons action,"The four dimensional Lorentz-breaking finite and determined Chern-Simons like
action is generated as a one loop perturbative correction via an appropriate
Lorentz-breaking coupling of the gauge field with the spinor field. Unlike the
known schemes of calculations, within this scheme this term is found to be
regularization independent.",0709.3090v2
2007-09-25,Lorentz transformations in de Sitter relativity,"The properties of Lorentz transformations in de Sitter relativity are
studied. It is shown that, in addition to leaving invariant the velocity of
light, they also leave invariant the length-scale related to the curvature of
the de Sitter spacetime. The basic conclusion is that it is possible to have an
invariant length parameter without breaking the Lorentz symmetry. This result
may have important implications for the study of quantum kinematics, and in
particular for quantum gravity.",0709.3947v1
2007-09-29,Wheeler's Gravitomagnetism Revisited I: A Purely Lorentz-Compton Approach to Vector Gravitational Waves and Trio-Holes,"A theory of vector gravitational waves is presented on the basis of an
additional gravitational field, recovering ideas that go back to H. A. Lorentz,
field that A. Wheeler called ``gravitomagnetism''. The theory is independent of
Einstein's General Relativity Theory, but is consistent with the
Einstein-Lorentz framework of Special Relativity, so that the resulting
equations are considered exact from the start, and not approximations valid for
velocities small compared with the speed of light. A simple model of mass
formation and presence of angular momentum started with a new type of
singularity, ``trio-holes'', is exhibited.",0710.0068v2
2007-12-13,Lorentz-violation-induced arrival delays of cosmological particles,"We point out that previous studies of possible Lorentz-violating effects in
astronomical time-of-flight data did not take into account the entire
implications of the universe's cosmological expansion. We present the
derivation of the accurate formulation of the problem and show that the
resulting correction of the limits on Lorentz violation is significant.",0712.2170v3
2007-12-17,Lorentz covariant statistical mechanics and thermodynamics of the relativistic ideal gas and preferred frame,"The Lorentz covariant classical and quantum statistical mechanics and
thermodynamics of an ideal relativistic gas of bradyons (particles slower than
light), luxons (particles moving with the speed of light) and tachyons
(hypothetical particles faster than light) is discussed. The Lorentz covariant
formulation is based on the preferred frame approach which among others enables
consistent, free of paradoxes description of tachyons. The thermodynamic
functions within the covariant approach are obtained both in classical and
quantum case.",0712.2725v2
2007-12-20,Invariant conserved currents in gravity theories: diffeomorphisms and local gauge symmetries,"Previously, we have developed a general method to construct invariant
conserved currents and charges in gravitational theories with Lagrangians that
are invariant under spacetime diffeomorphisms and local Lorentz
transformations. This approach is now generalized to the case when the local
Lorentz group is replaced by an arbitrary local gauge group. The particular
examples include the Maxwell and Yang-Mills fields coupled to gravity with
Abelian and non-Abelian local internal symmetries, and the metric-affine
gravity in which the local Lorentz spacetime group is extended to the local
general linear group.",0712.3547v1
2008-01-11,Nambu-Goldstone and Massive Modes in Gravitational Theories with Spontaneous Lorentz Breaking,"Spontaneous breaking of local Lorentz symmetry is of interest as a possible
mechanism originating from physics at the Planck scale. If such breaking
occurs, however, it raises the questions of what the fate of the
Nambu-Goldstone modes is, whether a Higgs mechanism can occur, and whether
additional massive modes (analogous to the Higgs particle) can appear. A
summary of some recent work looking at these questions is presented here.",0801.1711v2
2008-01-31,Two-dimensional Lorentz-violating Chern-Simons-like action,"We demonstrate generation of the two-dimensional Chern-Simons-like
Lorentz-breaking action via an appropriate Lorentz-breaking coupling of scalar
and spinor fields at zero as well as at the finite temperature and via the
noncommutative fields method and study the dispersion relations corresponding
to this action.",0801.4946v3
2008-02-05,Von Neumann Stability Analysis of Finite Difference Schemes for Maxwell--Debye and Maxwell--Lorentz Equations,"This technical report yields detailed calculations of the paper [1] (B.
Bid\'egaray-Fesquet, ""Stability of FD-TD schemes for Maxwell-Debye and
Maxwell-Lorentz equations"", Technical report, LMC-IMAG, 2005) which have been
however automated since (see
http://ljk.imag.fr/membres/Brigitte.Bidegaray/NAUtil/). It deals with the
stability analysis of various finite difference schemes for Maxwell--Debye and
Maxwell--Lorentz equations. This work gives a systematic and rigorous
continuation to Petropoulos previous work [5] (P.G. Petropoulos.,""Stability and
phase error analysis of FD-TD in dispersive dielectrics"", IEEE Transactions on
Antennas and Propagation, 42(1):62--69, 1994).",0802.0579v1
2008-02-29,Infrared-modified gravities and massive gravitons,"We review some theoretical and phenomenological aspects of massive gravities
in 4 dimensions. We start from the Fierz--Pauli theory with Lorentz-invariant
mass terms and then proceed to Lorentz-violating masses. Unlike the former
theory, some models with Lorentz-violation have no pathologies in the spectrum
in flat and nearly flat backgrounds and lead to interesting phenomenology.",0802.4379v1
2008-04-03,Kinetic transport in the two-dimensional periodic Lorentz gas,"The periodic Lorentz gas describes an ensemble of non-interacting point
particles in a periodic array of spherical scatterers. We have recently shown
that, in the limit of small scatterer density (Boltzmann-Grad limit), the
macroscopic dynamics converges to a stochastic process, whose kinetic transport
equation is not the linear Boltzmann equation--in contrast to the Lorentz gas
with a disordered scatterer configuration. The present paper focuses on the
two-dimensional set-up, and reports an explicit, elementary formula for the
collision kernel of the transport equation.",0804.0566v1
2008-04-18,Conductor inequalities and criteria for Sobolev-Lorentz two-weight inequalities,"In this paper we present integral conductor inequalities connecting the
Lorentz p,q-(quasi)norm of a gradient of a function to a one-dimensional
integral of the p,q-capacitance of the conductor between two level surfaces of
the same function. These inequalities generalize an inequality obtained by the
second author in the case of the Sobolev norm. Such conductor inequalities lead
to necessary and sufficient conditions for Sobolev-Lorentz type inequalities
involving two arbitrary measures.",0804.3051v1
2008-04-21,On general properties of Lorentz invariant formulation of noncommutative quantum field theory,"We study general properties of certain Lorentz invariant noncommutative
quantum field theories proposed in the literature. We show that causality in
those theories does not hold, in contrast to the canonical noncommutative field
theory with the light-wedge causality condition. This is the consequence of the
infinite nonlocality of the theory getting spread in all spacetime directions.
We also show that the time-ordered perturbation theory arising from the
Hamiltonian formulation of noncommutative quantum field theories remains
inequivalent to the covariant perturbation theory with usual Feynman rules even
after restoration of Lorentz symmetry.",0804.3341v2
2008-05-20,Spontaneous Symmetry Breaking of Lorentz and (Galilei) Boosts in (Relativistic) Many-Body Systems,"We extend a result by Ojima on spontaneous symmetry breaking of Lorentz
boosts in thermal (KMS) states and show that it is in fact a special case in a
more general class of examples of spontaneous symmetry breaking of Lorentz
symmetry in relativistic many-body systems. Furthermore we analyse the nature
of the corresponding Goldstone phenomenon and the type of Goldstone excitations
(provided they have particle character).",0805.3022v1
2008-05-22,On the dual equivalence between self-dual and Maxwell-Chern-Simons models with Lorentz symmetry breaking,"In this paper, we use gauge embedding procedure and master action approach to
establish the equivalence between the self-dual and Maxwell-Chern-Simons models
with Lorentz symmetry breaking. As a result, new kinds of Lorentz-breaking
terms arise.",0805.3517v4
2008-06-03,Lorentz-Covariant Non-Abelian Gauging of Supermembrane,"We perform the Lorentz-covariant non-Abelian gauging of supermembrane (M-2
brane) action. This is a generalization of our previous work based on
teleparallel formulation, in which Lorentz covariance was not manifest. We
introduce the Killing supervector \xi^{A I} with the adjoint index I for a
non-Abelian gauge group H. This formulation is applicable to the
compactification of supermembrane from eleven dimensions into D dimensions,
such as H = SO(11-D) for the compactification M_{11} \to S^{11-D} \times M_D
(1\le D \le 9).",0806.0660v1
2008-06-25,Existence and uniqueness results for the Boussinesq system with data in Lorentz spaces,"This paper is devoted to the study of the Cauchy problem for the Boussinesq
system with partial viscosity in dimension $N\geq3.$ First we prove a global
existence result for data in Lorentz spaces satisfying a smallness condition
which is at the scaling of the equations. Second, we get a uniqueness result in
Besov spaces with {\it negative} indices of regularity (despite the fact that
there is no smoothing effect on the temperature). The proof relies on a priori
estimates with loss of regularity for the nonstationary Stokes system with
convection. As a corollary, we obtain a global existence and uniqueness result
for small data in Lorentz spaces.",0806.4084v1
2008-10-04,A Lorentz Invariance Violating Cosmology on the DGP Brane,"We study cosmological implications of a Lorentz invariance violating
DGP-inspired braneworld scenario. A minimally coupled scalar field and a
single, fixed-norm, Lorentz-violating timelike vector field within an
interactive picture provide a wide parameter space which accounts for late-time
acceleration and transition to phantom phase of the scalar field.",0810.0765v2
2008-10-07,Inspecting absorption in the spectra of extra-galactic gamma-ray sources for insight into Lorentz invariance violation,"We examine what the absorbed spectra of extra-galactic TeV gamma-ray sources,
such as blazars, would look like in the presence of Lorentz invariance
violation (LIV). Pair-production with the extra-galactic background light
modifies the observed spectra of such sources, and we show that a violation of
Lorentz invariance would generically have a dramatic effect on this absorption
feature. Inspecting this effect, an experimental task likely practical in the
near future, can provide unique insight on the possibility of LIV.",0810.1318v2
2008-11-03,Confronting Finsler space-time with experiment,"Within all approaches to quantum gravity small violations of the Einstein
Equivalence Principle are expected. This includes violations of Lorentz
invariance. While usually violations of Lorentz invariance are introduced
through the coupling to additional tensor fields, here a Finslerian approach is
employed where violations of Lorentz invariance are incorporated as an integral
part of the space-time metrics. Within such a Finslerian framework a modified
dispersion relation is derived which is confronted with current high precision
experiments. As a result, Finsler type deviations from the Minkowskian metric
are excluded with an accuracy of 10^{-16}.",0811.0282v1
2008-11-09,Spinor fields without Lorentz frames in curved spacetime using complexified quaternions,"Using complexified quaternions, a formalism without Lorentz frames, and
therefore also without vierbeins, for dealing with tensor and spinor fields in
curved spacetime is presented. A local U(1) gauge symmetry, which, it is
speculated, might be related to electromagnetism, emerges naturally.",0811.1357v4
2008-12-23,Lorentz shear modulus of fractional quantum Hall states,"We show that the Lorentz shear modulus of macroscopically homogeneous
electronic states in the lowest Landau level is proportional to the bulk
modulus of an equivalent system of interacting classical particles in the
thermodynamic limit. Making use of this correspondence we calculate the Lorentz
shear modulus of Laughlin's fractional quantum Hall states at filling factor
$\nu=1/m$ ($m$ an odd integer) and find that it is equal to $\pm \hbar mn/4$,
where $n$ is the density of particles and the sign depends on the direction of
magnetic field. This is in agreement with the recent result obtained by Read in
arXiv:0805.2507 and corrects our previous result published in Phys. Rev. B {\bf
76}, 161305 (R) (2007).",0812.4331v1
2008-12-23,Dynamical Lorentz symmetry breaking in a 4D four-fermion model at finite temperature,"In a 4D four-fermion model we study the dynamical restoration of Lorentz and
CPT symmetries at finite temperature. We evaluate the gap equation both at zero
and at finite temperature and observe that, depending on the parameters of the
theory, there is a critical temperature at which the Lorentz and CPT symmetries
are restored.",0812.4394v1
2009-02-13,"On Lorentz Invariance, Spin-Charge Separation And SU(2) Yang-Mills Theory","Previously it has been shown that in spin-charge separated SU(2) Yang-Mills
theory Lorentz invariance can become broken by a one-cocycle that appears in
the Lorentz boosts. Here we study in detail the structure of this one-cocycle.
In particular we show that its non-triviality relates to the presence of a
(Dirac) magnetic monopole bundle. We also explicitely present the finite
version of the cocycle.",0902.2289v1
2009-03-24,A Novel Approach to Lorentz Gauge Theory,"This paper is devoted to introduce a gauge theory of the Lorentz Group based
on the analysis of isometric diffeomorphism-induced Lorentz transformations.
The behaviors under local transformations of fermion fields and spin
connections (assumed to be coordinate vectors) are analyzed and the role of the
torsion field in a curved space-time is discussed.",0903.4119v2
2009-04-13,Is the Lorentz contraction inevitable in the special theory of relativity ?,"We look afresh at the deduction of the ""Lorentz contraction"" of a ""rod"" from
the Lorentz transformation equations of the special theory of relativity. We
show that under special conditions, which include acceleration of the ""rod"",
length ""expansion"" and ""invariance"" are possible, and thus these are purely
kinematical phenomena. We then take a closer look at Einstein's two famous
papers on the special theory of relativity and point out a flaw in his
argument. It seems that it is possible to have the times of the clocks of two,
and indeed all, inertial systems to agree with each other.",0904.1913v1
2009-05-14,"Relative quantum phase, $m$-tangle, and multi-local Lorentz-group invariant","In this paper we establish a relation between quantum relative phase,
$m$-tangle, and multi-local Lorentz-group invariant or
$SL(2,\mathbb{C})^{\times m}$-invariant $S^{2}_{(m)}$. Our construction is
based on the orthogonal complement of a positive operator valued measure on
quantum phase. In particular, we propose a quantity based on the quantum
relative phase of a multi-qubit operator that coincides with
  $m$-tangle, and multi-local Lorentz-group invariant.",0905.2270v1
2009-06-12,Björling problem for timelike surfaces in the Lorentz-Minkowski space,"We introduce a new approach to the study of timelike minimal surfaces in the
Lorentz-Minkowski space through a split-complex representation formula for this
kind of surface. As applications, we solve the Bj\""orling problem for timelike
surfaces and obtain interesting examples and related results. Using the
Bj\""orling representation, we also obtain characterizations of minimal timelike
surfaces of revolution as well as of minimal ruled timelike surfaces in the
Lorentz-Minkowsi space.",0906.2361v1
2009-09-29,Long-baseline neutrino experiments as tests for Lorentz violation,"Precise tests of Lorentz invariance can be executed using neutrino
oscillations, which can provide sensitive measurements of suppressed signals of
new physics. This talk describes the neutrino sector of the Standard-Model
Extension, which represents a general modification of the Standard Model of
massive neutrinos to include Lorentz and CPT violation. Attainable
sensitivities as well as a framework to search for these violations are
presented for existing and future long-baseline neutrino experiments. The
applicability of this framework to short-baseline experiments is also
discussed.",0909.5360v1
2009-10-14,Lorentz invariance relations and Wandzura-Wilczek approximation,"A complete list of the so-called Lorentz invariance relations between parton
distribution functions is given and some of their consequences are discussed,
such as the Burkhardt-Cottingham sum rule. The violation of these relations is
considered in a model independent way. It is shown that several Lorentz
invariance relations are not violated in a generalized Wandzura-Wilczek
approximation, indicating that numerically their violation may be small.",0910.2567v1
2009-11-14,Enhancing non-Gaussianities by breaking local Lorentz invariance,"This talk briefly explains how the breaking of a Lorentz-invariant
description of nature at tiny space-time intervals might affect the
non-Gaussian character of the primordial fluctuations left by inflation. For
example, a model that contains irrelevant operators that only preserve the
spatial symmetries along constant-time surfaces can generate a larger
non-Gaussian component in the pattern of primordial fluctuations than is
ordinarily predicted by inflation. This property can be useful for constraining
models that allow some Lorentz violation at short distances, beyond the
constraints possible from the power spectrum alone.",0911.2786v1
2009-11-25,Fourier Multiplier Norms of Spherical Functions on the Generalized Lorentz Groups,"Our main result provides a closed expression for the completely bounded
Fourier multiplier norm of the spherical functions on the generalized Lorentz
groups. As a corollary, we find that there is no uniform bound on the
completely bounded Fourier multiplier norm of the spherical functions on the
generalized Lorentz groups. We extend the latter result to the remaining
connected, real rank one, simple Lie groups with finite center, and as an
application we obtain that each of the above mentioned groups has a completely
bounded Fourier multiplier, which is not the coefficient of a uniformly bounded
representation of the group on a Hilbert space.",0911.4977v1
2010-02-08,Particle Creation from Vacuum by Lorentz Violation,"It is shown that the vacuum state in presence of Lorentz violation can be
followed by a particle-full universe that represents the current status of the
universe. In this model the modification in dispersion relation (Lorentz
violation) is picked up representing the regime of quantum gravity. The result
can be interpreted such that the existence of the particles is an evidence for
quantum effects of gravity in the past. It is concluded that only the vacuum
state is sufficient to appear the matter fields spontaneously after the process
of semi-classical analysis.",1002.1533v1
2010-02-27,"Why does the Unruh effect rely on Lorentz invariance, while Hawking radiation does not ?","We show that without Lorentz invariance, the Unruh effect does not exist. We
use modified dispersion relations and describe in turn: the non-thermal nature
of the vacuum (defined in the preferred frame) restricted to the Rindler wedge,
the loss of the KMS property of the Wigthman function, the transition
amplitudes and transition rates of a uniformaly accelerated detector. This
situation seems to contrast with the Hawking radiation of acoustic black holes,
which under certain assumptions has been shown to be robust to a breaking of
Lorentz symmetry. We explain this discrepancy.",1003.0112v1
2010-06-23,T-Duality For String in Horava-Lifshitz Gravity,"We continue our study of the Lorentz breaking string theories. These theories
are defined as string theory with modified Hamiltonian constraint which breaks
the Lorentz symmetry of target space-time. We analyze properties of this theory
in the target space-time that possesses isometry along one direction. We also
derive the T-duality rules for Lorentz breaking string theories and show that
they are the same as that of Buscher's T-duality for the relativistic strings.",1006.4530v2
2010-07-06,On the initial-value problem of the Maxwell-Lorentz equations,"We consider the Maxwell-Lorentz equations, i.e., the equation of motion of a
charged dust coupled to Maxwell's equations, on an arbitrary
general-relativistic spacetime. We decompose this system of equations into
evolution equations and constraints, and we demonstrate that the evolution
equations are strongly hyperbolic. This result guarantees that the
initial-value problem of the Maxwell-Lorentz equations is well-posed. We
illustrate this general result with a discussion of spherically symmetric
solutions on Minkowski spacetime.",1007.0953v2
2010-09-07,An Investigation of the $K_{F}$-type Lorentz-Symmetry Breaking Gauge Models in $N=1$-Supersymmetric Scenario,"In this work, we present two possible venues to accomodate the $K_{F}$-type
Lorentz-symmetry violating Electrodynamics in an $N=1$-supersymmetric
framework. A chiral and a vector superfield are chosen to describe the
background that signals Lorentz-symmetry breaking. In each case, the $\ K_{\mu
\nu \kappa \lambda }$-tensor is expressed in terms of the components of the
background superfield that we choose to describe the breaking. We also present
in detail the actions with all fermionic partners of the background that
determine $\ K_{\mu \nu \kappa \lambda }$.",1009.1326v1
2010-09-07,Lorentz Invariance Violation Matrix from a General Principle,"We show that a general principle of physical independence or physical
invariance of mathematical background manifold leads to a replacement of the
common derivative operators by the covariant co-derivative ones. This
replacement naturally induces a background matrix, by means of which we obtain
an effective Lagrangian for the minimal standard model with supplement terms
characterizing Lorentz invariance violation or anisotropy of space-time. We
construct a simple model of the background matrix and find that the strength of
Lorentz violation of proton in the photopion production is of the order
$10^{-23}$.",1009.1331v1
2010-10-18,On the duality in four-dimensional Lorentz-breaking field theories,"We consider new issues of duality in four-dimensional Lorentz-breaking field
theories. In particular, we demonstrate that the arising of the aether-like
Lorentz-breaking term is necessary in order for the 4D models to display the
duality analog between the MCS and self-dual models in 3D. We further study the
dispersion relations in both theories and discuss the physical contents of the
models involved in this new dualilty.",1010.3666v1
2010-10-24,Radiatively induced Lorentz-violating operator of mass dimension five in QED,"The first higher derivative term of the photon sector of Lorentz-violating
QED, with operator of mass dimension $d=5$, is radiatively induced from the
fermion sector, in which contains a derivative term with the dimensionless
coefficient $g^{\lambda\mu\nu}$. The calculation is performed perturbatively in
the coefficient for Lorentz violation, and due to the fact that the
contributions are quadratically divergent, we adopt dimensional regularization.",1010.5013v2
2010-11-23,"Lorentz invariance, nonzero minimal uncertainty in position, and inhomogeneity of space at the Planck scale","The suspicion that the existence of a minimal uncertainty in position
measurements violates Lorentz invariance seems unfounded. It is shown that the
existence of such a nonzero minimal uncertainty in position is not only
consistent with Lorentz invariance, but that the latter also fixes the algebra
between position and momentum which gives rise to this minimal uncertainty. We
also investigate how this algebra affects the underlying quantum mechanical
structure, and why, at the Planck scale, space can no longer be considered
homogeneous.",1011.5234v2
2011-03-24,A Five Dimensional Space Without Local Lorentz Invariance,"A five dimensional space without invariance under local Lorentz
transformations is studied, and the transformations under which the theory is
invariant are introduced. We show that the Lorentz force is included in the
ensuing equations of motion. The four dimensional Einstein and Maxwell
equations emerge from the field equations while the homogeneous Maxwell
equations naturally appear in the work. A corresponding quantum theory is
introduced. The spectrum of a free particle and the hydrogen atom are
recovered. Quantum structure of Schwarzschild spaces are also studied.",1103.4660v1
2011-04-06,Lorentz invariant phenomenology of quantum gravity: Main ideas behind the model,"In the past decade the phenomenology of quantum gravity has been dominated by
the search of violations of Lorentz invariance. However, there are very serious
arguments that led us to assume that this invariance is a symmetry in Nature.
This motivated us to construct a phenomenological model describing how a
Lorentz invariant granular structure of spacetime could become manifest. The
proposal is fully covariant, it involves non-trivial couplings of curvature to
matter fields and leads to a well defined phenomenology.",1104.1150v1
2011-04-25,Renormalization of Scalar and Yukawa Field Theories with Lorentz Violation,"We consider a theory of scalar and spinor fields, interacting through Yukawa
and phi^4 interactions, with Lorentz-violating operators included in the
Lagrangian. We compute the leading quantum corrections in this theory. The
renormalizability of the theory is explicitly shown up to one-loop order. In
the pure scalar sector, the calculations can be generalized to higher orders
and to include finite terms, because the theory can be solved in terms of its
Lorentz-invariant version.",1104.4778v1
2011-06-06,Constraints on Lorentz Invariance Violation using INTEGRAL/IBIS observations of GRB041219A,"One of the experimental tests of Lorentz invariance violation is to measure
the helicity dependence of the propagation velocity of photons originating in
distant cosmological obejcts. Using a recent determination of the distance of
the Gamma-Ray Burst GRB 041219A, for which a high degree of polarization is
observed in the prompt emission, we are able to improve by 4 orders of
magnitude the existing constraint on Lorentz invariance violation, arising from
the phenomenon of vacuum birefringence.",1106.1068v1
2011-07-19,Consequences of vacuum polarization on electromagnetic waves in a Lorentz-symmetry breaking scenario,"The propagation of electromagnetic waves in a Lorentz-symmetry violating
scenario where there is a region of polarized vacuum is studied. It turns out
that the photon field acquires an interesting polarization state, possibly
useful to set up upper bounds in Lorentz-violating models at laboratory scales.",1107.3737v2
2011-08-05,Lattice spinor gravity,"We propose a regularized lattice model for quantum gravity purely formulated
in terms of fermions. The lattice action exhibits local Lorentz symmetry, and
the continuum limit is invariant under general coordinate transformations. The
metric arises as a composite field. Our lattice model involves no signature for
space and time, describing simultaneously a Minkowski or euclidean theory. It
is invariant both under Lorentz transformations and euclidean rotations. The
difference between space and time arises from expectation values of composite
fields. Our formulation includes local gauge symmetries beyond the generalized
Lorentz symmetry. The lattice construction can be employed for formulating
models with local gauge symmetries purely in terms of fermions",1108.1313v2
2011-08-18,Bounding Lorentz Violation at Particle Colliders By Tracking the Motion of Charged Particles,"In the presence of Lorentz violation, the motion of a charged particle in a
magnetic field is distorted. By measuring the eccentricities of particles'
elliptical orbits and studying how those eccentricities vary with the absolute
orientation of the laboratory, it is possible to constrain the
Lorentz-violating c_JK parameters. For each observed species, this method can
provide constraints on four linear combinations of coefficients for which, in
some species, there are presently no two-sided bounds.",1108.3827v2
2011-09-22,Maximal Invariants For Lorentz Wishart Models,"In this paper we consider two statistical hypotheses for the families of
Wishart type distributions. These distributions are analogs of the Wishart
distributions defined and parametrized over a Lorentz cone. We test these
hypotheses by means of maximal invariant statistics which are explicitly
derived in the paper. The testing problems, respectively, concern the
hypothesis that parameters are in a sub-Lorentz-cone, and the the hypothesis
that two observations have the same parameter.",1109.4699v2
2011-09-30,Lorentz noninvariant neutrino oscillations without neutrino mass,"The bicycle model of Lorentz noninvariant neutrino oscillations without
neutrino masses naturally predicts maximal mixing and a 1/E dependence of the
oscillation argument for $\nu_\mu \to \nu_\tau$ oscillations of atmospheric and
long-baseline neutrinos, but cannot also simultaneously fit the data for solar
neutrinos and KamLAND. We examine all nineteen possible structures of the
Standard Model Extension for Lorentz noninvariant oscillations of massless
neutrinos that naturally have a 1/E dependence at high neutrino energy. Due to
the lack of any evidence for direction dependence, we consider only
direction-independent oscillations. Although we find a number of models with a
1/E dependence for atmospheric and long-baseline neutrinos, none can also
simultaneously fit solar and KamLAND data.",1109.6860v1
2011-10-10,Consequences of Neutrino Lorentz Violation For Leptonic Meson Decays,"If the observation by OPERA of apparently superluminal neutrinos is correct,
the Lagrangian for second-generation leptons must break Lorentz invariance. We
calculate the effects of an energy-independent change in the neutrino speed on
another observable, the charged pion decay rate. The rate decreases by an
factor [1 - 3/(1 - (m_mu)^2 / (m_pi) ^ 2) (< v_(nu) > - 1)], where < v_(nu) >
is the (directionally averaged) neutrino speed in the pion's rest frame. This
provides a completely independent experimental observable that is sensitive to
the same forms of Lorentz violation as a neutrino time of flight measurement.",1110.2123v2
2011-10-10,Lorentz-violating dynamics in the pre-Planckian Universe,"We have recently proposed a Lorentz-violating energy-momentum relation
entailing an exact momentum cutoff and studied various physical applications of
that dispersion law. By a simple phenomenological approach we here study
Lorentz violation effects on early Universe and pre-Planckian cosmological
radiation. In particular, we predict an effective infinite speed of light soon
after the Big Bang instant, leading to a straightforward solution of the
horizon and flatness problems without recourse to inflation, cosmological
scalar fields or other ad hoc energy sources.",1110.2234v1
2011-12-06,New physics for superluminal particles,"In this paper, we consider the apparent superluminal speed of neutrinos in
their travel from CERN to Gran Susso, as measured by the OPERA experiment,
within the framework of the Extended Lorentz Transformation Model. The model is
based on a natural extension of Lorentz transformation by wick rotation. Scalar
and Dirac's fields are considered and invariance under the new lorentz group is
discussed. Moreover, an extension of quantum mechanics to accommodate new
particles is considered using the newly proposed Generalized-$\mathbb{C}$
quantum mechanics. A two dimensional representation of the new Dirac's equation
is therefore formulated and its solution is calculated.",1112.1222v4
2011-12-16,Spacelike surfaces with free boundary in the Lorentz-Minkowski space,"We investigate a variational problem in the Lorentz-Minkowski space $\l^3$
whose critical points are spacelike surfaces with constant mean curvature and
making constant contact angle with a given support surface along its common
boundary. We show that if the support surface is a pseudosphere, then the
surface is a planar disc or a hyperbolic cap. We also study the problem of
spacelike hypersurfaces with free boundary in the higher dimensional
Lorentz-Minkowski space $\l^{n+1}$.",1112.3936v1
2012-03-14,Quantum state of a free spin-1/2 particle and the inextricable dependence of spin and momentum under Lorentz transformations,"We revise the Dirac equation for a free particle and investigate Lorentz
transformations on spinors. We study how the spin quantization axis changes
under Lorentz transformations, and evince the interplay between spin and
momentum in this context.",1203.3147v2
2012-03-27,New perspective on space and time from Lorentz violation,"I present a brief review on space and time in different periods of physics,
and then talk on the nature of space and time from physical arguments. I
discuss the ways to test such a new perspective on space and time through
searching for Lorentz violation in some physical processes. I also make an
introduce to a newly proposed theory of Lorentz violation from basic
considerations.",1203.5852v2
2012-06-18,Non-Abelian Chiral 2-Form and M5-Branes,"We first review self-dual (chiral) gauge field theories by studying their
Lorentz non-covariant and Lorentz covariant formulations. We next construct a
non-Abelian self-dual two-form gauge theory in six dimensions with a spatial
direction compactified on a circle. This model reduces to the Yang-Mills theory
in five dimensions for a small compactified radius R. The model also reduces to
the Lorentz-invariant Abelian self-dual two-form theory when the gauge group is
Abelian. The model is expected to describe multiple 5-branes in M-theory. We
also discuss its decompactified limit, covariant formulation, BRST-antifield
quantization and other generalizations.",1206.3983v2
2012-07-06,The Lorentz-Dirac and Landau-Lifshitz equations from the perspective of modern renormalization theory,"This paper uses elementary techniques drawn from renormalization theory to
derive the Lorentz-Dirac equation for the relativistic classical electron from
the Maxwell-Lorentz equations for a classical charged particle coupled to the
electromagnetic field. I show that the resulting effective theory, valid for
electron motions that change over distances large compared to the classical
electron radius, reduces naturally to the Landau-Lifshitz equation. No
familiarity with renormalization or quantum field theory is assumed.",1207.1745v2
2012-08-03,Testing Lorentz violation with binary pulsars: constraints on standard model extension,"Under the standard model extension (SME) framework, Lorentz invariance is
tested in five binary pulsars: PSR J0737-3039, PSR B1534+12, PSR J1756-2251,
PSR B1913+16 and PSR B2127+11C. By analyzing the advance of periastron, we
obtain the constraints on a dimensionless combination of SME parameters that is
sensitive to timing observations. The results imply no evidence for the break
of Lorentz invariance at $10^{-10}$ level, one order of magnitude larger than
previous estimation.",1208.0736v1
2012-08-16,Low Energy Tests of Lorentz and CPT Violation,"An overview of the theoretical framework of the Standard Model Extension
(SME) that allows for a parametrization of Lorentz and CPT violating effects
using effective field theory will be presented. A review of current bounds on
these Lorentz violating parameters using various low-energy tests will be
reviewed. State-of-the-art measurements involving the Penning Trap, atomic
clock, torsion pendulum, and resonant cavities will be discussed. Different
experiments can provide stringent bounds on a variety of parameters coupled to
various fundamental particles including electrons, protons, neutrons, and
photons.",1208.3474v1
2012-08-27,On Lorentz and Einstein-Laub forces in material media,"As a continuation of the discussion started in (M. Mansuripur, Phys. Rev.
Lett. 108, 193901 (2012)), we show that the approach based on Lorentz force law
in material media, like Einstein-Laub expression for electromagnetic force,
gives relativistically consistent results, when the contribution of hidden
momentum is properly accounted for. An expression for the torque on point-like
electric/magnetic dipole is derived, which is compatible with both the Lorentz
and Einstein-Laub approaches.",1208.5296v1
2012-10-06,Fermion observables for Lorentz violation,"The relationship between experimental observables for Lorentz violation in
the fermion sector and the coefficients for Lorentz violation appearing in the
lagrangian density is investigated in the minimal Standard-Model Extension. The
definitions of the 44 fermion-sector observables, called the tilde
coefficients, are shown to have a block structure. The c coefficients decouple
from all the others, have six subspaces of dimension 1, and one of dimension 3.
The remaining tilde coefficients form eight blocks, one of dimension 6, one of
dimension 2, three of dimension 5, and three of dimension 4. By inverting these
definitions, thirteen limits on the electron-sector tilde coefficients are
deduced.",1210.2003v1
2012-10-08,The 4D-2D projection of Lorentz-violating Myers-Pospelov QED,"We consider the four-dimensional quantum electrodynamics extended with
Myers-Pospelov Lorentz-violating dimension-5 operators to investigate 4D-2D
projection. In projecting out the 4D theory down to a 2D theory we get analogs
of these operators. Namely, we obtain a new two-dimensional theory with
corresponding scalar and fermionic 2D Myers-Pospelov Lorentz-violating
dimension-3 operators. New defect structures can also be found from this new
projected out 2D scalar sector. Furthermore, we also show that this 2D scalar
sector can be also radiatively induced through the new 2D fermionic sector.",1210.2369v1
2012-11-28,Lorentz and CPT Violation in Scalar-Mediated Potentials,"In Lorentz- and CPT-violating effective field theories involving scalar and
spinor fields, there exist forms of Lorentz violation that modify only the
scalar-spinor Yukawa interaction vertices. These affect low-energy fermion and
antifermion scattering processes through modifications to the nonrelativistic
Yukawa potentials. The modified potentials involve novel combinations of
momentum, spin, and Lorentz-violating background tensors.",1211.6614v2
2012-12-07,"Static solitons, Lorentz invariance, and a new perspective on the integrability of the Sine Gordon equation in (1+2) dimensions","Contrary to the common understanding, the Sine-Gordon equation in (1+2)
dimensions does have N-soliton solutions for any N. The Hirota algorithm allows
for the construction of static N-soliton solutions (i.e., solutions that do not
depend on time) of that equation for any N. Lorentz transforming the static
solutions yields N-soliton solutions in any moving frame. They are scalar
functions under Lorentz transformations. In an N-soliton solution in a moving
frame, (N-2) of the (1+2)-dimensional momentum vectors of the solitons are
linear combinations of the two remaining vectors.",1212.1618v1
2013-03-04,Stückelberg Fields on the Effective p-brane,"We demonstrate the one-to-one correspondence between reparametrization
invariant effective actions for relativistic p-branes in flat target space and
effective actions for transverse brane perturbations with non-linearly realized
Poincar\'e symmetry. Starting with an action with non-linearly realized
symmetry we construct the corresponding reparametrization invariant action by
introducing St\""uckelberg fields. They combine with the transverse modes to
form a Lorentz vector. The manifest Lorentz symmetry of the reparametrization
invariant action follows directly from the non-linearly realized Lorentz
symmetry of the initial action in terms of the physical modes.",1303.0743v1
2013-03-10,Analytical studies on the Sunyaev Zeldovich effect in the cluster of galaxies for three Lorentz frames,"We study the Sunyaev-Zeldovich effect for clusters of galaxies. The Boltzmann
equations for the CMB photon distribution function are studied in three Lorentz
frames. We clarify the relations of the SZ effects among the different Lorentz
frames. We derive analytic expressions for the photon redistribution functions.
These formulas are applicable to the nonthermal electron distributions as well
as the standard thermal distribution. We show that the Fokker-Planck expansion
of the Boltzmann equation can be expanded by the power series of the diffusion
operator of the original Kompaneets equation.",1303.2286v2
2013-03-12,Nucleosynthesis constraint on Lorentz invariance violation in the neutrino sector,"We investigate the nucleosynthesis constraint on Lorentz invariance violation
in the neutrino sector which influences the formation of light elements by
altering the energy density of the Universe and weak reaction rates prior to
and during the big-bang nucleosynthesis epoch. We derive the weak reaction
rates in the Lorentz-violating extension of the standard model. Using
measurements of the primordial helium-4 and deuterium abundances, we give a
tighter constraint on the deformed parameter than that derived from
measurements of the cosmic microwave background anisotropies.",1303.2813v2
2013-03-12,An asymptotic estimate of the variance of the self-intersections of a planar periodic Lorentz process,"We consider a periodic planar Lorentz process with strictly convex obstacles
and finite horizon. This process describes the displacement of a particle
moving in the plane with unit speed and with elastic reflection on the
obstacles. We call number of self-intersections of this Lorentz process the
number V(n) of couples of integers (k,m) smaller than n such that the particle
hits a same obstacle both at the k-th and at the m-th collision times. The aim
of this paper is to prove that the variance of V(n) is equivalent to cn^2 (such
a result has recently been proved for simple planar random walks by
Deligiannidis and Utev).",1303.3034v1
2013-05-16,Aspects of semilocal BPS vortex in systems with Lorentz symmetry breaking,"It is shown the existence of a static self-dual semilocal vortex
configuration for the Maxwell-Higgs system with a Lorentz-violating CPT-even
term. The dependence of the vorticity upper limit on the Lorentz-break term is
also investigated.",1305.3868v2
2013-05-24,Lorentz Invariant CPT Violation for a Class of Nonlocal Thirring Model,"It is possible to construct Lorentz invariant CPT violating models for
Nonlocal Quantum Field Theory. In this article, we present a class of Nonlocal
Thirring Models, in which the CPT invariance is violated while the Lorentz
invariance is present. As a result, in certain cases the mass-splitting between
particle and antiparticle are identified.",1305.5817v2
2013-06-09,Symmetries shared by the Poincaré Group and the Poincaré Sphere,"Henri Poincar\'e formulated the mathematics of Lorentz transformations, known
as the Poincar\'e group. He also formulated the Poincar\'e sphere for
polarization optics. It is shown that these two mathematical instruments can be
derived from the two-by-two representations of the Lorentz group. Wigner's
little groups for internal space-time symmetries are studied in detail. While
the particle mass is a Lorentz-invariant quantity, it is shown possible to
address its variations in terms of the decoherence mechanism in polarization
optics.",1306.2017v1
2013-07-15,Transport coefficients in Lorentz plasmas with the power-law kappa-distribution,"Transport coefficients in Lorentz plasma with the power-law
kappa-distribution are studied by means of using the transport equation and
macroscopic laws of Lorentz plasma without magnetic field. Expressions of
electric conductivity, thermoelectric coefficient and thermal conductivity for
the power-law kappa-distribution are accurately derived. It is shown that these
transport coefficients are significantly modified by the kappa-parameter, and
in the limit of the parameter kappa to infinit they are reduced to the standard
forms for a Maxwellian distribution.modified",1307.3849v3
2013-07-15,Lorentz and CPT violation in the hydrogen spectrum,"We have studied the effect of hypothetical violations of Lorentz and CPT
symmetry by calculating the corrections to the energy levels of hydrogen
induced by the Standard-Model Extension (SME). Hydrogen studies are interesting
because the energy levels of hydrogen can be measured with great precision and
the theory for hydrogen based on the Standard Model (SM) is well understood. We
obtained corrections through order \alpha^2 times the SME parameters for all
levels of hydrogen and applied them to determine the SME corrections to the
transition frequency for the 2S-1S transition.",1307.4068v1
2013-07-18,Constraints on violations of Lorentz symmetry from Gravity Probe B,"We use the final results from Gravity Probe B to set new upper limits on the
gravitational sector of the Standard-Model Extension, including for the first
time the coefficient associated with the time-time component of the new field
responsible for inducing local Lorentz violation in the theory.",1307.4826v1
2013-07-19,Testing Lorentz Invariance with a Double-Pass Optical Ring Cavity,"We have developed an apparatus to test Lorentz invariance in the photon
sector by measuring the resonant frequency difference between two
counterpropagating directions of an asymmetric optical ring cavity using a
double-pass configuration. No significant evidence for the violation was found
at the level of $\delta c /c \lesssim 10^{-14}$. Details of our apparatus and
recent results are presented.",1307.5266v1
2013-07-19,"Unitarity, ghosts and nonminimal terms in Lorentz violating QED","The unitarity of a Lorentz-invariance violating QED model with higher-order
Myers and Pospelov photons coupled to standard fermions is studied. As
expected, we find ghost states associated to the higher-order terms that may
lead to the loss of unitarity. An explicit calculation to check perturbative
unitarity in the process of electron-positron scattering is performed and it is
found to be possible to be preserved.",1307.5341v1
2013-07-25,An odd (parity) test of Lorentz symmetry with atomic dysprosium,"We propose using a Stark interference technique to directly measure the
odd-parity c_{0j} components of the electron sector c_{\mu\nu} tensor of the
Standard-Model Extension. This technique has been shown to be a sensitive probe
of parity violation in atomic dysprosium in a low-energy, tabletop experiment,
and may also be straightforwardly applied to test Lorentz invariance. We
estimate that such an experiment may be sensitive to c_{0j} coefficients as
small as 10^{-18}.",1307.6762v1
2013-10-07,Optical-Cavity Limits on Higher-Order Lorentz Violation,"An optical ring cavity is used to place the first laboratory constraints on
parity-odd nonrenormalizable Lorentz violation. Variations in resonant
frequencies are limited to parts in $10^{15}$. Absolute sensitivity to
Lorentz-violating operators of mass dimension 6 is improved by a factor of a
million over existing parity-even microwave-cavity bounds. Sensitivity to
dimension-8 violations is improved by fourteen orders of magnitude.",1310.1952v2
2013-10-18,Some properties of multi-qubit systems under effect of the Lorentz transformation,"Effect of Lorentz transformation on some properties of multi-qubit systems is
investigated. It is shown that, properties like, the fidelity and entanglement
decay as the Wigner's angles increase, but can be improved, if all the
transformed particles are transformed with the same Wigner's angles. The upper
bounds of the average capacity of the GHZ state increases while it decreases
and more robust with the W-state as the Wigner's angle of the observer
decreases. Under Lorentz transformation, the tripartite states transform into
another equivalent states and hence no change on the efficiency of these states
to perform quantum information tasks.",1310.4974v1
2013-11-04,Limits on Lorentz and CPT violation from double beta decay,"Deviations from Lorentz and CPT invariance in the neutrino sector and their
observable effects in double beta decay are studied. For two-neutrino double
beta decay, a spectral distortion and its properties are characterized for
different isotopes. Majorana couplings for Lorentz violation are studied and
shown to trigger neutrinoless double beta decay even for negligible Majorana
mass. Existing data are used to obtain first limits of $5 \times 10^{-9}$ for
18 individual coefficients and attainable sensitivities in current and future
experiments are presented.",1311.0930v2
2013-12-15,Lorentz-symmetry violation and dynamical flavour oscillations,"We show how a mass mixing matrix can be generated dynamically, for two
massless fermion flavours coupled to a Lorentz invariance violating (LIV) gauge
field. The LIV features play the role of a regulator for the gap equations, and
the non-analytic dependence of the dynamical masses, as functions of the gauge
coupling, allows to consider the limit where the LIV gauge field eventually
decouples from the fermions. Lorentz invariance is then recovered, to describe
the oscillation between two free fermion flavours, and we check that the finite
dynamical masses are the only effects of the original LIV theory.",1312.4143v1
2013-12-13,On the nature of the new group LB1,"The new local group LB1 introduced previously will be studied in detail,
depicting its unique nature that makes it a new group in fundamental physics.
It will be made clear that even though most of its elements are Lorentz
transformations, one unique discrete transformation not present in the Lorentz
groups, is making this group into a new group. In fact there will be two kinds
of discrete transformations, one a Lorentz transformation, the other not. It is
these discrete transformations that allow for an isomorphism between the group
SO(2) and LB1. An isomorphism between the compact group SO(2) and the
non-compact group SO(1,1) plus two kinds of discrete transformations that make
up the new group LB1.",1312.5636v1
2014-01-15,Minimal AdS-Lorentz supergravity in three-dimensions,"The $\mathcal{N}=1$ AdS-Lorentz superalgebra is studied and its relationship
to semigroup expansion developed. Using this mathematical tool, the invariant
tensors and Casimir operators are found. In terms of these invariants, a
three-dimensionnal Chern--Simons supergravity action with AdS-Lorentz symmetry
is constructed. The Killing spinors for a BTZ black-hole like solution of the
theory are discussed.",1401.3697v4
2014-07-31,The Slow Gravitino,"When the supersymmetry breaking sector is a fluid background, Lorentz
invariance is broken spontaneously. The super-Higgs mechanism leads to a
gravitino Lagrangian with Lorentz symmetry violating terms. We analyse the
resulting field equations and constraints. We identify the physical spin 3/2
and spin 1/2 helicity states, derive their equations of motion and construct
the propagator. The violation of Lorentz symmetry implies that the longitudinal
mode has a non-relativistic dispersion relation, whose speed is lower than the
speed of light. We briefly comment on possible implications to gravitino
cosmology and phenomenology.",1407.8321v1
2014-08-25,Tests of Lorentz symmetry in single beta decay,"Low-energy experiments studying single beta decay can serve as sensitive
probes of Lorentz invariance that can complement interferometric searches for
deviations from this spacetime symmetry. Experimental signatures of a
dimension-three operator for Lorentz violation that are unobservable in
neutrino oscillations are described for the decay the polarized and unpolarized
neutrons as well as for measurements of the spectral endpoint in beta decay.",1408.5880v1
2014-09-20,Electromagnetic force and torque in Lorentz and Einstein-Laub formulations,"The Lorentz force law of classical electrodynamics requires the introduction
of hidden energy and hidden momentum in situations where an electric field acts
on a magnetic material. In contrast, the Einstein-Laub formulation does not
invoke hidden entities. The total force and torque exerted by electromagnetic
fields on a given object are independent of whether the force and torque
densities are evaluated using the law of Lorentz or that of Einstein and Laub.
Hidden entities aside, the two formulations differ only in their predicted
force and torque distributions throughout material media.",1409.5860v1
2014-09-24,Tests of Lorentz and CPT Violation in the Medium Baseline Reactor Antineutrino Experiment,"Tests of Lorentz and CPT violation in the medium baseline reactor
antineutrino experiment are presented in the framework of the Standard Model
Extension (SME). Both the spectral distortion and sidereal variation are
employed to derive the limits of Lorentz violation (LV) coefficients. We do the
numerical analysis of the sensitivity of LV coefficients by taking the Jiangmen
Underground Neutrino Observatory (JUNO) as an illustration, which can improve
the sensitivity by more than two orders of magnitude compared with the current
limits from reactor antineutrino experiments.",1409.6970v2
2014-11-24,Fick's Law for the Lorentz Model in a weak coupling regime,"In this paper we deal with further recent developments, strictly connected to
the recent result obtained by Basile, Nota, Pezzotti and Pulvirenti. We
consider the Lorentz gas out of equilibrium in a weak coupling regime. Each
obstacle of the Lorentz gas generates a smooth radially symmetric potential
with compact support. We prove that the macroscopic current in the stationary
state is given by the Fick's law of diffusion. The diffusion coefficient is
given by the Green-Kubo formula associated to the generator of the diffusion
process dictated by the linear Landau equation.",1411.6474v1
2015-01-11,Finsler-like structures from Lorentz-breaking classical particles,"A method is presented for deducing classical point-particle Lagrange
functions corresponding to a class of quartic dispersion relations. Applying
this to particles violating Lorentz symmetry in the minimal Standard-Model
Extension leads to a variety of novel lagrangians in flat spacetime. Morphisms
in these classical systems are studied that echo invariance under field
redefinitions in the quantized theory. The Lagrange functions found offer new
possibilities for understanding Lorentz-breaking effects by exploring parallels
with Finsler-like geometries.",1501.02490v1
2015-02-04,Lorentz transformations for massive two-particle systems: entanglement change and invariant subspaces,"Lorentz boosts on particles with spin and momentum degrees of freedom induce
momentum-dependent rotations. Since, in general, different particles have
different momenta, the transformation on the whole state is not a
representation of the rotation group. Here we identify the group that acts on a
two-particle system and, for the case when the momenta of the particles are
correlated, find invariant subspaces that have interesting properties for
quantum information processes in relativistic scenarios. A basis of states is
proposed for the study of transformations of spin states under Lorentz boosts,
which is a good candidate for building quantum communication protocols in
relativistic scenarios.",1502.01080v1
2015-03-19,Lorentz-violating inflationary magnetogenesis,"A non-conformally invariant coupling between the inflaton and the photon in
the minimal Lorentz-violating standard model extension is analyzed. For
specific forms of the Lorentz-violating background tensor, the strong-coupling
and backreaction problems of magnetogenesis in de Sitter inflation with scale
$\sim 10^{16}$GeV are evaded, the electromagnetic-induced primordial spectra of
(Gaussian and non-Gaussian) scalar and tensor curvature perturbations are
compatible with cosmic microwave background observations, and the
inflation-produced magnetic field directly accounts for cosmic magnetic fields.",1503.07415v2
2015-05-15,Emergent Lorentz invariance with chiral fermions,"We study renormalization group flows in strongly interacting field theories
with fermions that correspond to transitions between a theory without Lorentz
invariance at high energies down to a theory with approximate Lorentz symmetry
in the infrared. Holographic description of the strong coupling is used. The
emphasis is made on emergence of chiral fermions in the low-energy theory.",1505.04130v2
2015-05-19,On the Lorentz-breaking theory with higher derivatives in spinor sector,"We consider the two-point function of the gauge field in Lorentz-breaking
theories with higher-derivative extension of the Dirac Lagrangian. We show that
the Carroll-Field-Jackiw term naturally arises in this theory as a quantum
correction being perfectly finite and thus displaying no ambiguities. Also, the
finiteness of this term at low energy limit and the absence of large Lorentz
violating corrections allows to avoid the fine-tuning problem.",1505.04968v2
2015-06-03,Lorentz breaking supersymmetry and Horava-Lifshitz-like models,"We present a Lorentz-breaking supersymmetric algebra characterized by a
critical exponent $z$. Such construction requires a non trivial modification of
the supercharges and superderivatives. The improvement of renormalizability for
supersymmetric scalar QED is shown and the K\""ahlerian effective potentials are
calculated in different cases. We also show how the theory flows naturally to
the Lorentz symmetric case at low energies.",1506.01331v2
2015-07-14,Lorentz contraction of the equal-time Bethe-Salpeter amplitude in two-dimensional massless quantum electrodynamics,"The Lorentz transformation properties of the equal-time bound-state
Bethe-Salpeter amplitude in the two-dimensional massless quantum
electrodynamics (the so called Schwinger Model) are considered. It is shown
that while boosting a bound state (a `meson') this amplitude is subject to
approximate Lorentz contraction. The effect is exact for large separations of
constituent particles (`quarks'), while for small distances the deviation is
more significant. For this phenomenon to appear, the full} function, i.e. with
the inclusion of all instanton contributions has to be considered. The
amplitude in each separate topological sector does not exhibit such properties.",1507.04036v2
2015-09-18,Wigner-Eckart theorem and Jordan-Schwinger representation for infinite-dimensional representations of the Lorentz group,"The Wigner-Eckart theorem is a well known result for tensor operators of
SU(2) and, more generally, any compact Lie group. This paper generalises it to
arbitrary Lie groups, possibly non-compact. The result relies on knowledge of
recoupling theory between finite-dimensional and arbitrary admissible
representations, which may be infinite-dimensional; the particular case of the
Lorentz group will be studied in detail. As an application, the Wigner-Eckart
theorem will be used to construct an analogue of the Jordan-Schwinger
representation, previously known only for finite-dimensional representations of
the Lorentz group, valid for infinite-dimensional ones.",1509.05633v1
2015-10-13,Matter-Sector Lorentz Violation in Binary Pulsars,"Violations of local Lorentz invariance in the gravitationally coupled matter
sector have yet to be sought in strong-gravity systems. We present the
implications of matter-sector Lorentz violation for orbital perturbations in
pulsar systems and show that the analysis of pulsar data can provide
sensitivities to these effects that exceed the current reach of solar system
and laboratory tests by several orders of magnitude.",1510.03798v1
2015-10-21,Klein-Gordon and Dirac Equations with Thermodynamic Quantities,"We study the thermodynamic quantities such as the Helmholtz free energy, the
mean energy and the specific heat for both the Klein-Gordon, and Dirac
equations. Our analyze includes two main subsections: ($i$) statistical
functions for the Klein-Gordon equation with a linear potential having Lorentz
vector, and Lorentz scalar parts ($ii$) thermodynamic functions for the Dirac
equation with a Lorentz scalar, inverse-linear potential by assuming that the
scalar potential field is strong ($A \gg 1$). We restrict ourselves to the case
where only the positive part of the spectrum gives a contribution to the sum in
partition function. We give the analytical results for high temperatures.",1510.06393v1
2015-10-29,"Essential conformal actions of PSL(2,R) on real-analytic compact Lorentz manifolds","The main result of this paper is the conformal flatness of real-analytic
compact Lorentz manifolds of dimension at least $3$ admitting a conformal
essential (i.e. conformal, but not isometric) action of a Lie group locally
isomorphic to PSL(2,R). It is established by using a general result of M.
Gromov on local isometries of real-analytic $A$-rigid geometric structures. As
corollary, we deduce the same conclusion for conformal essential actions of
connected semi-simple Lie groups on real-analytic compact Lorentz manifolds.
This work is a contribution to the understanding of the Lorentzian version of a
question asked by A. Lichnerowicz.",1510.08812v1
2015-11-27,Speed addition and closed time cycle in Lorentz-non-invariant theories,"In theories, whose Lorentz invariance is violated by involvement of an
external any-rank tensor, we show that the standard relativistic rule still
holds true for summing the signal speed, understood as the group velocity of a
wave, with the speed of the reference frame. Provided a superluminal signal is
available, this observation enables one to arrange a closed time cycle and
hence causality violation, notwithstanding the Lorentz noninvariance. Also an
optical anisotropy of a moving medium, isotropic at rest, is revealed.",1511.08785v1
2016-03-05,Tree-level equivalence between a Lorentz-violating extension of QED and its dual model in electron-electron scattering,"S-matrix amplitudes for the electron-electron scattering are calculated in
order to verify the quantum equivalence of dual models. We used an extended
Quantum Electrodynamics with CPT-even Lorentz-violating kinetic and mass terms,
which was used in a process of gauge embedding, known as Noether dualizationn
method (NDM), in order to generate its gauge-invariant dual model. The physical
equivalence was established at tree-level and the cross section was calculated
to second order in the Lorentz-violating parameter.",1603.01738v2
2016-03-14,Cerenkov-Like Emission of Pions by Photons in a Lorentz-Violating Theory,"In the presence of Lorentz violation, the Cerenkov-like process
$\gamma\rightarrow\gamma+\pi^{0}$ may become allowed for sufficiently energetic
photons. Photons above the threshold would lose energy rapidly through pion
emission. The fact that propagating photons with energies of up to 80 TeV
survive to be observed on Earth allows us to place a one-sided constraint on an
isotropic Lorentz violating parameter at the $7\times 10^{-13}$ level; this is
more than an order of magnitude better than best previous result.",1603.04491v2
2016-04-19,"Cromlech, menhirs and celestial sphere: an unusual representation of the Lorentz group","We present a novel representation of the Lorentz group, the geometric version
of which uses ""reversions"" of a sphere while the algebraic version uses
pseudounitary 2x2 matrices over complex numbers and quaternions, and Clifford
algebras in general. A remarkably simple formula for relativistic composition
of velocities and an accompanying geometric construction follows. The method is
derived from the diffeomorphisms of the celestial sphere induced by Lorentz
boost.",1604.05698v1
2016-04-20,Lorentz and CPT violation in the Standard-Model Extension,"Lorentz and CPT invariance are among the symmetries that can be investigated
with ultrahigh precision in subatomic physics. Being spacetime symmetries,
Lorentz and CPT invariance can be violated by minuscule amounts in many
theoretical approaches to underlying physics that involve novel spacetime
concepts, such as quantized versions of gravity. Regardless of the underlying
mechanism, the low-energy effects of such violations are expected to be
governed by effective field theory. This talk provides a survey of this idea
and includes an overview of experimental efforts in the field.",1604.05898v1
2016-04-29,Low-Energy Lorentz Invariance in Lifshitz Nonlinear Sigma Models,"This work is dedicated to the study of both large-$N$ and perturbative
quantum behaviors of Lifshitz nonlinear sigma models with dynamical critical
exponent $z=2$ in 2+1 dimensions. We discuss renormalization and
renormalization group aspects with emphasis on the possibility of emergence of
Lorentz invariance at low energies. Contrarily to the perturbative expansion,
where in general the Lorentz symmetry restoration is delicate and may depend on
stringent fine-tuning, our results provide a more favorable scenario in the
large-$N$ framework. We also consider supersymmetric extension in this
nonrelativistic situation.",1604.08924v2
2016-07-13,Measurements of CPT Violation at LHCb,"Recent measurements of CPT violation and Lorentz symmetry breaking in
$B^0-\bar{B}^0$ mixing and $B^0_s-\bar{B}^0_s$ mixing, obtained from data taken
by the LHCb experiment, are highlighted. The results are expressed in terms of
the Standard-Model Extension (SME) coefficients, which incorporate both CPT and
Lorentz violation. Due to the large boost of the $B$ mesons at LHCb, the SME
coefficients can be determined with high precision. The bounds on these
coefficients are improved significantly compared to previous measurements.",1607.03620v1
2016-07-19,"Ultra-High Energy Astrophysical Neutrino Detection, and the Search for Lorentz Invariance Violations","A growing class of ultra-high energy neutrino (UHE-nu) observatories based on
the Askaryan effect and Antarctic ice is able to search for Lorentz invariance
violation (LIV). The ARA, ARIANNA, ANITA and EVA collaborations have the power
to constrain the Standard Model Extension (SME) by measuring the flux and
energy distribution of neutrinos created through the GZK process. The future
expansion of ARA, at the South Pole, pushes the discovery potential further.",1607.05745v2
2016-07-20,Musings on Lorentz Violation Given the Recent Gravitational-Wave Observations of Coalescing Binary Black Holes,"The recent observation of gravitational waves by the LIGO/Virgo collaboration
provides a unique opportunity to probe the extreme gravity of coalescing binary
black holes. In this regime, the gravitational interaction is not only strong,
but the spacetime curvature is large, characteristic velocities are a
non-negligible fraction of the speed of light, and the time scale on which the
curvature and gravity change is small. This contribution discusses some
consequences of these observations on modifications to General Relativity, with
a special emphasis on Lorentz-violating theories.",1607.05787v1
2016-07-20,Testing Lorentz Symmetry using Chiral Perturbation Theory,"We consider the low-energy effects of a selected set of Lorentz- and
CPT-violating quark and gluon operators by deriving the corresponding chiral
effective lagrangian. Using this effective lagrangian, low-energy hadronic
observables can be calculated. We apply this to magnetometer experiments and
derive the best bounds on some of the Lorentz-violating coefficients. We point
out that progress can be made by studying the nucleon-nucleon potential, and by
considering storage-ring experiments for deuterons and other light nuclei.",1607.05987v1
2016-07-23,Lorentz-Invariance Violation with Higher-Order Operators,"In this work, in the light of the developments for indefinite metric theories
made by Lee and Wick, we study perturbative unitarity in a Lorentz-invariance
violating QED model with higher-order operators. We show that by following the
Lee-Wick prescription it is possible to preserve unitarity in the model at
one-loop order in the coupling.",1607.06984v1
2016-07-24,Lorentz and CPT Violation in Heavy Quark Physics,"Violations of the Lorentz and CPT symmetries can appear as observable effects
in the direct production of top quarks and their subsequent decays. Earlier
results for the $q\bar{q}$ production process for $t\bar{t}$ pairs have been
extended to include the gluon fusion process which dominates at the LHC. In
addition results are obtained for testing CPT symmetry through single top quark
production.",1607.07056v1
2016-07-25,Gauge anomalies in Lorentz-violating QED,"In this work we study the issue of gauge anomalies in Lorentz-violating QED.
To do so, we opt to use the Becchi-Rouet-Stora-Tyutin formalism within the
algebraic renormalization approach, reducing our study to a cohomology problem.
Since this approach is independent of the renormalization scheme, the results
obtained here are expected to be general. We find that the Lorentz-violating
QED is free of gauge anomalies to all orders in perturbation theory.",1607.07413v2
2016-07-22,"Laser Gyroscopes, Gravity, and the SME","In this contribution to the CPT'16 proceedings, we illustrate the potential
use of ring-laser systems in searching for Lorentz violation in the framework
of the Standard-Model Extension. We present expressions for the
Lorentz-violating contribution to the ring-laser signal for a sample system and
make sensitivity estimates for the GINGER project.",1607.08111v1
2016-10-10,On Biconservative Lorentz Hypersurface with non-diagonalizable shape operator,"In this paper, we obtain some properties of biconservative Lorentz
hypersurface $M_{1}^{n}$ in $E_{1}^{n+1}$ having shape operator with complex
eigen values. We prove that every biconservative Lorentz hypersurface
$M_{1}^{n}$ in $E_{1}^{n+1}$ whose shape operator has complex eigen values with
at most five distinct principal curvatures has constant mean curvature. Also,
we investigate such type of hypersurface with constant length of second
fundamental form having six distinct principal curvatures.",1610.03005v3
2016-10-13,Lorentz Hypersurfaces satisfying $\triangle \vec {H}= α\vec {H}$ with non diagonal shape operator,"We study Lorentz hypersurfaces $M_{1}^{n}$ in $E_{1}^{n+1}$ satisfying
$\triangle \vec {H}= \alpha \vec {H}$ with non diagonal shape operator, having
complex eigenvalues. We prove that every such Lorentz hypersurface in
$E_{1}^{n+1}$ having at most five distinct principal curvatures has constant
mean curvature.",1610.04095v1
2016-10-27,Lorentz violation and deep inelastic scattering,"The effects of quark-sector Lorentz violation on deep inelastic
electron-proton scattering are studied. We show that existing data can be used
to establish first constraints on numerous coefficients for Lorentz violation
in the quark sector at an estimated sensitivity of parts in a million.",1610.08755v2
2017-03-30,Mass generation by a Lorentz-invariant gas of spacetime defects,"We present a simple model of defects embedded in flat spacetime, where the
model is designed to maintain Lorentz invariance over large length scales. Even
without remnant Lorentz violation, there are still effects from these spacetime
defects on the propagation of physical fields, notably mass generation for
scalars and Dirac fermions.",1703.10585v4
2017-08-17,Measurement of the Lorentz-FitzGerald Body Contraction,"A complete foundational discussion of acceleration in context of Special
Relativity is presented. Acceleration allows the measurement of a
Lorentz-FitzGerald body contraction created. It is argued that in the back
scattering of a probing laser beam from a relativistic flying electron cloud
mirror generated by an ultra-intense laser pulse, a first measurement of a
Lorentz-FitzGerald body contraction is feasible.",1708.05670v1
2017-08-17,Testing Lorentz Symmetry using High Energy Astrophysics Observations,"We discuss some of the tests of Lorentz symmetry made possible by
astrophysical observations of ultrahigh energy cosmic rays, gamma-rays, and
neutrinos. These are among the most sensitive tests of Lorentz symmetry
violation because they are the highest energy phenomena known to man.",1708.05672v2
2017-08-29,Heavy and heavy-light mesons and the Lorentz structure of the quark-antiquark interaction,"We solve a Minkowski-space integral equation, derived in the Covariant
Spectator Theory, for quark-antiquark bound states describing heavy and
heavy-light mesons. The equation's kernel contains a one-gluon exchange
interaction and a covariant generalization of a linear confining potential with
a mixed scalar, pseudoscalar, and vector Lorentz structure, characterized by a
continuous mixing parameter. We investigate to what extent the Lorentz
structure of the confining kernel can be determined by fitting the mixing
parameter to the meson spectrum.",1708.08862v1
2018-11-26,Transport properties and ageing for the averaged Lévy-Lorentz gas,"We consider a persistent random walk on an inhomogeneous environment where
the reflection probability depends only on the distance from the origin. Such
an environment is the result of an average over all realizations of disorder of
a L\'evy-Lorentz (LL) gas. Here we show that this averaged L\'evy-Lorentz gas
yields nontrivial results even when the related LL gas is trivial. In
particular, we investigate its long time transport properties such as the mean
square displacement and the statistics of records, as well as the occurrence of
ageing phenomena.",1811.10252v2
2019-05-02,A central potential with a massive scalar field in a Lorentz symmetry violation environment,"We investigate the behaviour of a massive scalar field under the influence of
a Coulomb-type and central linear central potentials inserted in the
Klein-Gordon equation by modifying the mass term in the spacetime with Lorentz
symmetry violation. We consider the presence of a background constant vector
field which characterizes the breaking of the Lorentz symmetry and show that
analytical solutions to the Klein-Gordon equation can be achieved.",1905.00939v1
2019-05-09,Lorentz-invariant mass and entanglement of biphoton states,"The concept of the Lorentz-invariant mass of a group of particles is shown to
be applicable to biphoton states formed in the process of spontaneous
parametric down conversion. The conditions are found when the Lorentz-invariant
mass is related directly with (proportional to) the Schmidt parameter $K\gg 1$
determining a high degree of entanglement of a biphoton state with respect to
transverse wave vectors of emitted photons.",1905.03459v1
2019-05-23,Symmetries in the SME gravity sector: A study in the first-order formalism,"A method to find the symmetries of a theory in the first order formalism of
gravity is presented. This method is applied to the minimal gravity sector of
the Standard Model Extension. It is argued that no inconsistencies arise when
Lorentz violation is explicit and the relation between Lorentz violation and
invariance under (active) diffeomorphisms is clearly exposed.",1905.09850v1
2020-07-22,Higher-order one-loop renormalization in the spinor sector of minimal LV extended QED,"We calculate contributions to the one-loop renormalization in the spinor
sector of the minimal Lorentz-violating extended QED in the second order in
Lorentz-breaking parameters. From the renormalizability viewpoint, we show that
the inclusion of some of the Lorentz-breaking terms in the model is linked to
the presence of others. We also demonstrate that the Ward identities are
satisfied up to this order.",2007.11538v1
2010-05-11,Centre-of-mass and internal symmetries in classical relativistic systems,"The internal symmetry of composite relativistic systems is discussed. It is
demonstrated that Lorentz-Poincar\'e symmetry implies the existence of internal
moments associated with the Lorentz boost, which are Laplace-Runge-Lenz (LRL)
vectors. The LRL symmetry is thus found to be the internal symmetry universally
associated with the global Lorentz transformations, in much the same way as
internal spatial rotations are associated with global spatial rotations. Two
applications are included, for an interacting 2-body system and for an
interaction-free many-body system of particles. The issue of localizability of
the relativistic CM coordinate is also discussed.",1005.1818v2
2010-05-17,Laboratory Bounds on Electron Lorentz Violation,"Violations of Lorentz boost symmetry in the electron and photon sectors can
be constrained by studying several different high-energy phenomenon. Although
they may not lead to the strongest bounds numerically, measurements made in
terrestrial laboratories produce the most reliable results. Laboratory bounds
can be based on observations of synchrotron radiation, as well as the observed
absences of vacuum Cerenkov radiation. Using measurements of synchrotron energy
losses at LEP and the survival of TeV photons, we place new bounds on the three
electron Lorentz violation coefficients c_(TJ), at the 3 x 10^(-13) to 6 x
10^(-15) levels.",1005.2994v1
2013-08-09,The Search for Neutrino-Antineutrino Mixing from Lorentz Invariance Violation using Neutrino Interactions in MINOS,"We searched for a sidereal modulation in the rate of neutrinos observed by
the MINOS far detector. The detection of these signals could be a signature of
neutrino-antineutrino mixing due to Lorentz and CPT violation as described by
the Standard-Model Extension framework. We found no evidence for these sidereal
signals and we placed limits on the coefficients in this theory describing the
effect.",1308.2256v1
2013-08-17,Extended-Lorentz Quantum-Cosmology Symmetry Group,"Unitarily representable by transformations of Milne quantum-universe (MQU)
Hilbert-space vectors is a 9-parameter 'extended-Lorentz' Lie group whose
algebra comprises 9 conserved MQU-constituent ('quc') attributes: electric
charge, energy, spirality, 3-vector momentum and 3-vector angular momentum.
Commutation with the full symmetry algebra by the 3-element Lorentz-extending
sub-algebra identifies any quc by its (permanent) trio of charge, spirality and
energy integers. Milne's redshift-specifying 'universe age' is invariant under
the MQU symmetry group. Also invariant is the (elsewhere specified) universe
hamiltonian--a self-adjoint age-dependent Hilbert-space operator (not a
symmetry-algebra member) that generates universe evolution with increasing age
through a 'Schrodinger' (first-order) differential equation.",1308.4366v2
2014-03-04,Three-dimensional Lorentz-violating action,"We demonstrate the generation of the three-dimensional Chern-Simons-like
Lorentz-breaking ``mixed"" quadratic action via an appropriate Lorentz-breaking
coupling of vector and scalar fields to the spinor field and study some
features of the scalar QED with such a term. We show that the same term emerges
through a nonpertubative method, namely the Julia-Toulouse approach of
condensation of charges and defects.",1403.0786v1
2014-03-17,The Banach fixed point principle viewed as a monotone convergence with respect to the Lorentz cone,"We augment the dimension of the Euclidean space by one and the Picard
iteration of a contraction by a simple iteration on the real line such that the
resulting iteration becomes monotone increasing and bounded with respect to the
order defined by the Lorentz cone of the augmented space. This provides a
different way of showing the convergence of the Picard iteration of a
contraction, exhibiting the strong relationship between the Banach fixed point
principle and the ordering structure of the Euclidean space ordered by the
Lorentz cone.",1403.4028v2
2016-11-30,Testing local Lorentz invariance with short-range gravity,"The Newton limit of gravity is studied in the presence of Lorentz-violating
gravitational operators of arbitrary mass dimension. The linearized modified
Einstein equations are obtained and the perturbative solutions are constructed
and characterized. We develop a formalism for data analysis in laboratory
experiments testing gravity at short range and demonstrate that these tests
provide unique sensitivity to deviations from local Lorentz invariance.",1611.10313v1
2009-12-30,Lorentz Covariant k-Minkowski Spacetime,"In recent years, different views on the interpretation of Lorentz covariance
of non commuting coordinates were discussed. Here, by a general procedure, we
construct the minimal canonical central covariantisation of the k-Minkowski
spacetime. We then show that, though the usual k-Minkowski spacetime is
covariant under deformed (or twisted) Lorentz action, the resulting framework
is equivalent to taking a non covariant restriction of the covariantised model.
We conclude with some general comments on the approach of deformed covariance.",0912.5451v3
2011-11-04,Probes of Lorentz Violation,"Lorentz invariance is such an important principle of fundamental physics that
it should constantly be subjected to experimental scrutiny as well as
theoretical questioning. Distant astrophysical sources of energetic photons
with rapid time variations, such as active galactic nuclei (AGNs) and gamma-ray
bursters (GRBs), provide ideal experimental opportunities for testing Lorentz
invariance. The Cherenkov Telescope Array (CTA) is an excellent experimental
tool for making such tests with sensitivities exceeding those possible using
other detectors.",1111.1178v1
2011-11-26,Lorentz Process with shrinking holes in a wall,"We ascertain the diffusively scaled limit of a periodic Lorentz process in a
strip with an almost reflecting wall at the origin. Here, almost reflecting
means that the wall contains a small hole waning in time. The limiting process
is a quasi-reflected Brownian motion, which is Markovian but not strong
Markovian. Local time results for the periodic Lorentz process, having
independent interest, are also found and used.",1111.6193v2
2012-01-29,Cosmic censorship of smooth structures,"It is observed that on many 4-manifolds there is a unique smooth structure
underlying a globally hyperbolic Lorentz metric. For instance, every
contractible smooth 4-manifold admitting a globally hyperbolic Lorentz metric
is diffeomorphic to the standard $\R^4$. Similarly, a smooth 4-manifold
homeomorphic to the product of a closed oriented 3-manifold $N$ and $\R$ and
admitting a globally hyperbolic Lorentz metric is in fact diffeomorphic to
$N\times \R$. Thus one may speak of a censorship imposed by the global
hyperbolicty assumption on the possible smooth structures on
$(3+1)$-dimensional spacetimes.",1201.6070v2
2012-04-03,Lorentz violation bounds on Bhabha scattering,"We investigate the effect of Lorentz-violating terms on Bhabha scattering in
two distinct cases correspondent to vectorial and axial nonminimal couplings in
QED. In both cases, we find significant modifications with respect to the usual
relativistic result. Our results reveal an anisotropy of the differential cross
section which imply new constraints on the possible Lorentz violating terms.",1204.0755v2
2012-04-06,Gravitating tensor monopole in a Lorentz-violating field theory,"We present a solution of the coupled Einstein and rank-two antisymmetric
tensor field equations where Lorentz symmetry is spontaneously broken, and we
discuss its observational signatures. Especially, the deflection angles have
important qualitative differences between tensor and scalar monopoles. If a
monopole were to be detected, it would be discriminated whether or not to
correspond to a tensor one. This phenomenon might open up new direction in the
search of Lorentz violation with future astrophysical observations.",1204.1401v1
2013-09-17,Local Lorentz-Symmetry Breaking and Gravity,"The lagrangian-based Standard-Model Extension framework offers a broad
description of possible gravitational effects from local Lorentz violation. In
this talk, I review the status of the theoretical and phenomenological work in
this area. The extension of previous results in linearized gravity to the
nonlinear regime is discussed.",1309.4479v1
2013-09-18,Bipartite-Finsler spaces and the bumblebee model,"We present a proposal to include Lorentz-violating effects in gravitational
field by means of the Finsler geometry. In the Finsler set up, the length of an
event depends both on the point and the direction in the space-time. We briefly
review the bumblebee model, where the Lorentz violation is induced by a
spontaneous symmetry breaking due to the bumblebee vector field.The main
geometrical concepts of the Finsler geometry are outlined. Using a Finslerian
Einstein-Hilbert action we derive the bumblebee action from the bipartite
Finsler function with a correction to the gravitational constant.",1309.4671v1
2014-05-23,Absence of Long-Wavelength Cerenkov Radiation With Isotropic Lorentz and CPT Violation,"Modified theories of electrodynamics that include violations of Lorentz
symmetry often allow for the possibility of vacuum Cerenkov radiation. This
phenomenon has previously been studied in a number of Lorentz-violating
theories, but none of the methods that have previously been developed are
sufficient to study a theory with a timelike Chern-Simons term $k_{AF}$,
because such a term may generate exponentially growing solutions to the field
equations. Searching for vacuum Cerenkov radiation in a theory with a purely
timelike Chern-Simons term using only elementary methods, we find that, despite
the presence of the runaway modes, a charge in uniform nonrelativistic motion
does not radiate energy, up to second order in the velocity.",1405.6189v1
2014-05-26,The BTZ black hole as a Lorentz-flat geometry,"It is shown that 2+1 dimensional anti-de Sitter spacetimes are Lorentz-flat.
This means, in particular, that any simply-connected patch of the BTZ black
hole solution can be endowed with a Lorentz connection that is locally pure
gauge. The result can be naturally extended to a wider class of black hole
geometries and point particles in three-dimensional spacetime.",1405.6657v1
2014-05-30,Extended Lorentz cones and mixed complementarity problems,"In this paper we extend the notion of a Lorentz cone. We call a closed convex
set isotone projection set with respect to a pointed closed convex cone if the
projection onto the set is isotone (i.e., monotone) with respect to the order
defined by the cone. We determine the isotone projection sets with respect to
an extended Lorentz cone. In particular a Cartesian product between an
Euclidean space and any closed convex set in another Euclidean space is such a
set. We use this property to find solutions of general mixed complementarity
problems in an iterative way.",1405.7835v2
2014-06-26,Neutrinos as probes of Lorentz invariance,"Neutrinos can be used to search for deviations from exact Lorentz invariance.
The worldwide experimental program in neutrino physics makes these particles a
remarkable tool to search for a variety of signals that could reveal minute
relativity violations. This paper reviews the generic experimental signatures
of the breakdown of Lorentz symmetry in the neutrino sector.",1406.6838v1
2015-12-11,Bimetric Gravity From Adjoint Frame Field In Four Dimensions,"We provide a novel model of gravity by using adjoint frame fields in four
dimensions. It has a natural interpretation as a gravitational theory of a
complex metric field, which describes interactions between two real metrics.
The classical solutions establish three appealing features. The spherical
symmetric black hole solution has an additional hair, which includes the
Schwarzschild solution as a special case. The de Sitter solution is realized
without introducing a cosmological constant. The constant flat background
breaks the Lorentz invariance spontaneously, although the Lorentz breaking
effect can be localized to the second metric while the first metric still
respects the Lorentz invariance.",1512.03759v1
2015-12-27,Product of Independent Cauchy-Lorentz Random Matrices,"We investigate the product of $n$ complex non-Hermitian, independent random
matrices, each of size $N_i\times N_{i+1}$ $(i=1,...,n)$, with independent
identically distributed Cauchy entries (Cauchy-Lorentz matrices). The joint
probability distribution of the complex eigenvalues of the product matrix is
found to be given by a determinantal point process as in the case of a single
Cauchy-Lorentz matrix, but with weight given by a Meijer G-function depending
on $n$ and $N_i$.",1512.08179v3
2016-05-02,Spacetime Variation of Lorentz-Violation Coefficients at Nonrelativistic Scale,"The notion of uniform and/or constant tensor fields of rank $>0$ is
incompatible with general curved spacetimes. This work considers the
consequences of certain tensor-valued coefficients for Lorentz violation in the
Standard-Model Extension varying with spacetime position. We focus on two of
the coefficients, $a_\mu$ and $b_\mu$, that characterize Lorentz violation in
massive fermions, particularly in those fermions that constitute ordinary
matter. We calculate the nonrelativistic hamiltonian describing these effects,
and use it to extract the sensitivity of several precision experiments to
coefficient variation.",1605.00512v2
2016-08-10,Use of the gravitational-wave interferometers to test Lorentz invariance violation,"Currently operating gravitational-wave interferometers are Michelson
interferometers with effective arm length L ~ 4x10e5 m. While the
interferometer remains in lock, data at the fsr sideband frequency encode
information on slow phase changes in the f ~ 10e-5 Hz range, with a fringe
sensitivity ~ 10e-10. Preliminary LIGO data presented in 2009 show no Lorentz
violating signal at the second harmonic of the Earth's sidereal frequency. This
sets a limit on a possible change in refractine index, dn/n < 2x10e-22, an
improvement of more than three orders of magnitude over existing limits.",1608.03489v1
2016-08-19,First Search for Lorentz and CPT Violation in Double Beta Decay with EXO-200,"This proceedings contribution reports the first experimental search for
Lorentz- and CPT-violating signals specifically studying the effect of the
Standard-Model Extension (SME) oscillation-free momentum-independent neutrino
coupling operator in the double beta decay process. The search has been
performed using an exposure of 100 kg yr of $^{136}$Xe with the EXO-200
detector. No significant evidence of the spectral modification due to isotropic
Lorentz violation was found. A two-sided limit of $-2.65 \times 10^{-5}$ GeV
$<$ $\mathring{a}_{\mathrm{of}}^{(3)}$ $< 7.60 \times 10^{-6}$ GeV (90% C.L.)
is placed on the relevant coefficient within the SME.",1608.05748v1
2016-08-23,Search for Violation of CPT and Lorentz Invariance in $B^0_s$ Meson Oscillations using the D0 Detector,"A search is presented for CPT-violating effects in the mixing of $B^0_s$
mesons using the D0 detector at the Fermilab Tevatron Collider. The
CPT-violating asymmetry in the decay $B^0_s \rightarrow \mu^{\pm} D_s^{\mp} X$
as a function of sidereal phase is measured. No evidence for CPT-violating
effects is observed and limits are placed on CPT- and Lorentz-invariance
violating coupling coefficients.",1608.06935v1
2016-12-14,Relativistic Chiral Kinetic Theory from Quantum Field Theories,"The chiral kinetic theory of Weyl fermions with collisions in the presence of
weak electric and magnetic fields is derived from quantum field theories. It is
found that the side-jump terms in the perturbative solution of Wigner functions
play a significant role for the derivation. Moreover, such terms manifest the
breaking of Lorentz symmetry for distribution functions. The Lorentz covariance
of Wigner functions thus leads to modified Lorentz transformation associated
with side-jump phenomena further influenced by background fields and
collisions.",1612.04630v2
2016-12-27,Superconducting-Gravimeter Tests of Local Lorentz Invariance,"Superconducting-gravimeter measurements are used to test the local Lorentz
invariance of the gravitational interaction and of matter-gravity couplings.
The best laboratory sensitivities to date are achieved via a maximum-reach
analysis for 13 Lorentz-violating operators, with some improvements exceeding
an order of magnitude.",1612.08495v2
2017-06-02,Biconservative Lorentz hypersurfaces in $\mathbb{E}_{1}^{\lowercase{n}+1}$ with complex eigenvalues,"Our paper is an attempt to to verify the Chen's conjecture on biharmonic
submanifolds and to classify biconservative submanifolds.
  In doing so we provide an affirmative answer to Chen's conjecture on
biharmonic submanifolds. We prove that every biconservative Lorentz
hypersurface $M_{1}^{n}$ in $\mathbb{E}_{1}^{n+1}$ having complex eigenvalues
has constant mean curvature. Moreover, every biharmonic Lorentz hypersurface
$M_{1}^{n}$ having complex eigenvalues in $\mathbb{E}_{1}^{n+1}$ must be
minimal.",1706.00783v2
2017-07-04,Semisimple Weakly Symmetric Pseudo--Riemannian Manifolds,"We develop the classification of weakly symmetric pseudo--riemannian
manifolds $G/H$ where $G$ is a semisimple Lie group and $H$ is a reductive
subgroup. We derive the classification from the cases where $G$ is compact, and
then we discuss the (isotropy) representation of $H$ on the tangent space of
$G/H$ and the signature of the invariant pseudo--riemannian metric. As a
consequence we obtain the classification of semisimple weakly symmetric
manifolds of Lorentz signature $(n-1,1)$ and trans--Lorentz (conformal Lorentz)
signature $(n-2,2)$.",1707.01181v3
2017-07-25,Dynamical Lorentz symmetry breaking in a 4D massless four-fermion model,"In this paper, we study the spontaneous Lorentz symmetry breaking for a
four-dimensional massless four-fermion model. Our methodology is based on use
of the rationalized propagator. We show that a bumblebee potential arises as a
result of one-loop calculations and displays nontrivial minima. Also we
demonstrate that a phase transition restoring Lorentz invariance can occur at a
finite temperature.",1707.07778v2
2017-10-06,Quantization of Space-like States in Lorentz-Violating Theories,"Lorentz violation frequently induces modified dispersion relations that can
yield space-like states that impede the standard quantization procedures. In
certain cases, an extended hamiltonian formalism can be used to define
observer-covariant normalization factors for field expansions and phase space
integrals. These factors extend the theory to include non-concordant frames in
which there are negative-energy states. This formalism provides a rigorous way
to quantize certain theories containing space-like states and allows for the
consistent computation of Cherenkov radiation rates in arbitrary frames and
avoids singular expressions.",1710.02479v1
2017-10-07,"Polynomial decay of correlations for flows, including Lorentz gas examples","We prove sharp results on polynomial decay of correlations for nonuniformly
hyperbolic flows. Applications include intermittent solenoidal flows and
various Lorentz gas models including the infinite horizon Lorentz gas.",1710.02671v4
2017-10-12,Lorentz violation parameters and noncommutative scale,"We consider the noncommutative Standard Model that contains Lorentz symmetry
violation as a subset of the Standard Model extension. We introduce a constant
electromagnetic field as a background to derive mutual relations between the
free parameters of both theories. As the Lorentz violation parameters of the
Standard Model extension are extensively explored in different experiments and
many stringent bounds on these parameters are available, we can find new bounds
on the scale of noncommutativity of the order of a few to tens of teraelectron
volts.",1710.04402v1
2017-10-14,Lorentz-boosted evanescent waves,"Polarization, spin, and helicity are important properties of electromagnetic
waves. It is commonly believed that helicity is invariant under the Lorentz
transformations. This is indeed so for plane waves and their localized
superpositions. However, this is not the case for evanescent waves, which are
well-defined only in a half-space, and are characterized by complex wave
vectors. Here we describe transformations of evanescent electromagnetic waves
and their polarization/spin/helicity properties under the Lorentz boosts along
the three spatial directions.",1710.05145v2
2017-11-30,Manifestly Lorentz-covariant variables for the phase space of general relativity,"We present a manifestly Lorentz-covariant description of the phase space of
general relativity with the Immirzi parameter. This formulation emerges after
solving the second-class constraints arising in the canonical analysis of the
Holst action. We show that the new canonical variables give rise to other
Lorentz-covariant parametrizations of the phase space via canonical
transformations. The resulting form of the first-class constraints in terms of
new variables is given. In the time gauge, these variables and the constraints
become those found by Barbero.",1712.00040v2
2017-12-04,Cosmology in the Universe with distance dependent Lorentz-violating bakground,"We consider a cosmological setup with the inflaton field in the presence of a
redshift dependent Lorentz-violating time-like background to address the
inflationary regime and other phases of the Universe. We also show that the
regime of dark energy at large distances (low redshifts) is essentially
dominated by the presence of the Lorentz-violating background.",1712.00995v1
2017-12-06,$CP^{(N-1)}$ model in aether-superspace,"In this paper we study the dynamical generation of mass in the
Lorentz-violating $CP^{(N-1)}$ model defined in two and three-dimensional
aether-superspace. We show that even though the model presents a phase
structure similar to the usual, Lorentz invariant case, the dynamically
generated mass by quantum corrections has a dependence on the Lorentz violating
background properties, except for spacelike LV vector parameter. This is to be
contrasted with the behavior of the quantum electrodynamics in the
two-dimensional aether-superspace, where the dynamical generation of mass was
shown to exhibit an explicit dependence on the aether parameters in every
possible case.",1712.02650v2
2018-10-11,Elastic light-by-light scattering in a nonminimal Lorentz violation scenario,"In the last years the Lorentz Violation scheme was implemented in QFT, in
special in standard model of particle physics, in an attempt to explain our
actual open problems. In this work we analyze nonminimal couplings between a
Lorentz-violating 4-vector and the photon field and the leptonic current of
QED. The 1-loop contribution of the elastic photon-photon scattering is showed
and the novel characteristics which arose are pointed out.",1810.05202v2
2018-10-18,Lorentz symmetry is relevant,"We set up a covariant renormalisation group equation on a foliated spacetime
which preserves background diffeomorphism symmetry. As a first application of
the new formalism, we study the effect of quantum fluctuations in Lorentz
symmetry breaking theories of quantum gravity. It is found that once a small
breaking is introduced e.g. at the Planck scale, quantum fluctuations enhance
this breaking at low energies. A numerical analysis shows that the
magnification is of order unity for trajectories compatible with a small
cosmological constant. The immediate consequence is that the stringent
observational constraints on Lorentz symmetry breaking are essentially
scale-independent and must be met even at the Planck scale.",1810.07971v1
2019-06-13,Constraints on Lorentz Invariance Violations from Gravitational Wave Observations,"Using a deformed dispersion relation for gravitational waves, Advanced LIGO
and Advanced Virgo have been able to place constraints on violations of local
Lorentz invariance as well as the mass of the graviton. We summarise the method
to obtain the current bounds from the 10 significant binary black hole
detections made during the first and second observing runs of the above
detectors.",1906.05933v2
2019-06-29,CPT- and Lorentz-Violation Tests with Muon g-2,"The status of Lorentz- and CPT-violation searches using measurements of the
anomalous magnetic moment of the muon is reviewed. Results from muon g-2
experiments have set the majority of the most stringent limits on Standard-
Model Extension Lorentz and CPT violation in the muon sector. These limits are
consistent with calculations of the level of Standard-Model Extension effects
required to account for the current 3.7{\sigma} experiment-theory discrepancy
in the muon's g-2. The prospects for the new Muon g-2 Experiment at Fermilab to
improve upon these searches is presented.",1907.00162v1
2019-07-02,Renormalization in Nonminimal Lorentz-Violating Field Theory,"We provide the first step towards renormalization in a nonminimal
Lorentz-violating model consisting of normal scalars and modified fermions with
mass dimension five operators. We compute the radiative corrections
corresponding to the scalar self-energy, and we show that some divergencies are
improved and in the scalar sector they are finite. The pole mass of the scalar
two-point function is found and shown to lead to modifications of asymptotic
states.",1907.01621v1
2019-07-09,Search for Lorentz Violation Using High-Energy Atmospheric Neutrinos In IceCube,"High-energy atmospheric neutrinos observed by the IceCube Neutrino
Observatory are extremely sensitive probes of Lorentz violation (LV). Here we
report the result of analyzing two years of IceCube data in the search for LV.
This analysis places some of the strongest constraints on LV when considering
high-dimensional operators.",1907.04244v1
2019-07-12,Lorentz Violation and Sagnac Gyroscopes,"Sagnac gyroscopes with increased sensitivity are being developed and operated
with a variety of goals including the measurement of General-Relativistic
effects. We show that such systems can be used to search for Lorentz violation
within the field-theoretic framework of the Standard-Model Extension, and that
competitive sensitivities can be achieved. Special deviations from the inverse
square law of gravity are among the phenomena that can be effectively sought
with these systems. We present the necessary equations to obtain sensitivities
to Lorentz violation in relevant experiments.",1907.05933v2
2019-07-15,Searches for Lorentz-Violating Signals with Astrophysical Polarization Measurements,"Astrophysical observations are a powerful tool to constrain effects of
Lorentz-invariance violation in the photon sector. Objects at high redshifts
provide the longest possible baselines, and gamma-ray telescopes allow us to
observe some of the highest energy photons. Observations include polarization
measurements and time-of-flight measurements of transient or variable objects
to constrain vacuum birefringence and dispersion. Observing multiple sources
covering the entire sky allows the extraction of constraints on anisotropy. In
this paper, I review methods and recent results on Lorentz- and CPT-invariance
violation constraints derived from astrophysical polarization measurements in
the framework of the Standard-Model Extension.",1907.06514v1
2019-07-16,Isometries on non-commutative (quantum) Lorentz spaces associated with semi-finite von Neumann algebras,"In this article we characterize the extreme points of the unit ball of a
non-commutative (quantum) Lorentz space associated with a semi-finite von
Neumann algebra. This enables us to show that surjective isometries between
non-commutative Lorentz spaces are projection disjointness preserving and
finiteness preserving, which facilitates a characterization of the structure of
these isometries.",1907.07619v2
2019-06-11,Recent progress on probing Lorentz violation at HUST,"This work mainly introduces the recent experimental process on probing the
effect of Lorentz violation (LV) at d = 6, which is a specially striped-type
structure experiment to increase the signal of LV. Besides, we also proposed a
new experimental design using the striped geometry with triplex modulation to
independently constrain the 14 LV coefficients with a higher sensitivity.",1907.08685v1
2019-09-22,$\varepsilon$-regularity criteria in Lorentz spaces to the 3D Navier-Stokes equations,"In this paper, we are concerned with regularity of suitable weak solutions of
the 3D Navier-Stokes equations in Lorentz spaces. We obtain
$\varepsilon$-regularity criteria in terms of either the velocity, the gradient
of the velocity, the vorticity, or deformation tensor in Lorentz spaces. As an
application, this allows us to extend the result involving Leray's blow up rate
in time, and to show that the number of singular points of weak solutions
belonging to $ L^{p,\infty}(-1,0;L^{q,l}(\mathbb{R}^{3})) $ and $
{2}/{p}+{3}/{q}=1$ with $3<q<\infty$ and $q\leq l <\infty$ is finite.",1909.09957v2
2019-10-08,Influence of exact Lorentz-violating mechanism on the critical exponents for massive $q$-deformed $λφ^{4}$ scalar field theory,"We probe the influence of Lorentz-violating mechanism, treated exactly, on
the radiative quantum corrections to critical exponents for massive
$q$-deformed O($N$) $\lambda\phi^{4}$ scalar field theories. We attain that
task by employing three distinct and independent field-theoretic
renormalization group methods. Firstly we compute the critical exponents up to
the finite next-to-leading order for then generalizing the results for any loop
level. We show that the $q$-deformed critical exponents are insensible to the
Lorentz symmetry breaking mechanism thus agreeing with the universality
hypothesis.",1910.03567v1
2020-12-12,Nonminimal Lorentz Violation in Macroscopic Matter,"The effects of Lorentz and CPT violations on macroscopic objects are
explored. Effective composite coefficients for Lorentz violation are derived in
terms of coefficients for electrons, protons, and neutrons in the
Standard-Model Extension, including all minimal and nonminimal violations. The
hamiltonian and modified Newton's second law for a test body are derived. The
framework is applied to free-fall and torsion-balance tests of the weak
equivalence principle and to orbital motion. The effects on continuous media
are studied, and the frequency shifts in acoustic resonators are calculated.",2012.08302v1
2021-01-08,Lévy processes on the Lorentz-Lie algebra,"L\'evy processes in the sense of Sch\""urmann on the Lie algebra of the
Lorentz grouop are studied. It is known that only one of the irreducible
unitary representations of the Lorentz group admits a non-trivial one-cocycle.
A Sch\""urmann triple is constructed for this cocycle and the properties of the
associated L\'evy process are investigated. The decommpositions of the
restrictions of this triple to the Lie subalgebras $so(3)$ and $so(2,1)$ are
described.",2101.02967v1
2017-04-30,On the difference between Poincaré and Lorentz gravity,"The Poincar\'e invariance of GR is usually interpreted as Lorentz invariance
plus diffeomorphism invariance. In this paper, by introducing the local
inertial coordinates (LIC), it is shown that a theory with Lorentz and
diffeomorphism invariance is not necessarily Poincar\'e invariant. Actually,
the energy-momentum conservation is violated there. On the other hand, with the
help of the LIC, the Poincar\'e invariance is reinterpreted as an internal
symmetry. In this formalism, the conservation law is derived, which has not
been sufficiently explored before.",1705.00297v2
2017-05-17,Joint weak type interpolation on Lorentz-Karamata spaces,"We present sharp interpolation theorems, including all limiting cases, for a
class of quasilinear operators of joint weak type acting between
Lorentz-Karamata spaces over $\sigma$-finite measure. This class contains many
of the important integral operators. The optimality in the scale of
Lorentz-Karamata spaces is also discussed. The proofs of our results rely on a
characterization of Hardy-type inequalities restricted to monotone functions
and with power-slowly varying weights. Some of the limiting cases of these
inequalities have not been considered in the literature so far.",1705.06334v1
2018-06-04,Consideration of Covariant Quantization of Electromagnetic Field,"We examine a covariant quantization of electromagnetic fields by using an
operator derived from a constant scalar that can be called extended Lorentz
gauge. The quantization can avoid an inconsistency between Lorentz gauge and a
commutation relation, which can eliminate the need for introduction of physical
state defined by a subsidiary condition and auxiliary field in Lagrangian
density in Lorentz gauge. By using this quantization and indefinite metric
straightforwardly, all quantum phenomena can be provided without enigmatic and
paradoxical ""probability interpretation"".",1806.02175v2
2018-06-18,Cosmology in a toy model of Lorentz breaking gravity,"We explore cosmological solutions to Lorentz breaking gravity using the
gravitational sector of the Standard Model Extension (SME). By using a simple
toy model for Lorentz violation and under the assumption that the so-called
$\mathfrak{T}$-tensor is covariantly constant, we show that the gravity sector
SME influences basic cosmology. If the approach used in this toy model is valid
these results should point the way for more sofisticated studies.",1806.06767v1
2018-06-22,Shadowing Neutrino Mass Hierarchy with Lorentz Invariance Violation,"The effects of Lorentz Invariance Violation(LIV) operators up to dimension 6
in long baseline neutrino experiments are discussed, in specific for DUNE and
T2K. A phenomenological Lagrangian is proposed followed by a computation of the
effective Hamiltonian of neutrino propagation in matter for mass eigenstates.
It is shown that the simplest dimension 4 Lorentz violation parameter can
decrease DUNE sensitivity to neutrino mass hierarchy. Also, a $\chi^2$ analysis
is performed to obtain the expected long-baseline constraints to the LIV
operators up to dimension 6.",1806.08752v2
2018-07-09,Remarks on the static potential in theories with Lorentz violation terms,"We study the impact of Lorentz violating terms on a physical observable for
both electrodynamics of chiral matter and an Abelian Higgs-like model in $3+1$
dimensions. Our calculation is done within the framework of the
gauge-invariant, but path-dependent, variables formalism. Interestingly enough,
for electrodynamics of chiral matter we obtain a logarithmic correction to the
usual static Coulomb potential. Whereas for a Abelian Higgs model with a
Lorentz-breaking term, our result displays new corrections to the Yukawa
potential.",1807.02907v2
2018-08-10,"Lorentz invariant ""potential magnetic field"" and magnetic flux conservation in an ideal relativistic plasma","Lorentz invariant scalar functions of the magnetic field are defined in an
ideal relativistic plasma. These invariants are advected by the plasma fluid
motion and play the role of the {\it potential magnetic field} introduced by R.
Hide in Ann. Geophys. 1, 59 (1983) on the line of Ertel's theorem. From these
invariants we recover the Cauchy conditions for the magnetic field components
in the Eulerian-Lagrangian variable mapping. In addition the adopted procedure
allows us to formulate Alfv\`en theorem for the conservation of the magnetic
flux through a surface comoving with the plasma in a Lorentz invariant form.",1808.03458v1
2019-01-24,Notes: An assessment of some closed-form expressions for the Voigt function III: Combinations of the Lorentz and Gauss functions,"A variety of ""pseudo-Voigt"" functions, i.e. a linear combination of the
Lorentz and Gauss function (occasionally augmented with a correction term),
have been proposed as a closed-form approximation for the convolution of the
Lorentz and Gauss function known as the Voigt function. First, a compact review
of several approximations using a consistent notation is presented. The
comparison with accurate reference values indicates relative errors as large as
some percent.",1901.08366v1
2019-03-11,On calculating response functions via their Lorentz integral transforms,"The accuracy of reconstruction of a response function from its Lorentz
integral transform is studied in an exactly solvable model. An inversion
procedure is elaborated in detail and features of the procedure are studied.
Unlike results in the literature pertaining to the same model, the response
function is reconstructed from its Lorentz integral transform with rather high
accuracy.",1903.04189v1
2019-03-20,Photon splitting constraint on Lorentz Invariance Violation from Crab Nebula spectrum,"We calculate the decay width of the photon splitting into three photons in a
model of quantum electrodynamics with broken Lorentz invariance. We show that
this process can lead to a cut-off in the very-high-energy part of a photon
spectra of astrophysical sources. We obtain the 95\% CL bound on the Lorentz
violating mass scale for photons from the analysis of the very-high-energy part
of the Crab Nebula spectrum, obtained by HEGRA. This bound improves previous
constraints by more than an order of magnitude.",1903.08464v2
2019-03-22,Structured light pulses and their Lorentz-invariant mass,"Lorentz-invariant mass and mean propagation velocity have been found for
structured light pulses in vacuum considered as relativistic objects. We solved
the boundary problem for such widely known field configurations as Gauss,
Laguerre-Gauss, Bessel-Gauss, Hermite-Gauss, and Airy-Gauss ones. The pulses
were taken having the finite duration temporal envelope. We discovered that
Lorentz-invariant mass and mean propagation velocity significantly depend on
the spatial-temporal structure of pulses. We found that mean propagation
velocity is independent of the full energy of the pulse and is smaller than the
speed of light.",1903.10338v3
2019-08-12,A massive scalar field under the effects of the Lorentz symmetry violation by a CPT-odd non-minimal coupling,"In this paper, based on the Standard Model Extended gauge sector, we made a
non-minimal coupling in the Klein-Gordon equation which characterizes the
Lorentz symmetry violation and, through this nonminimal CPT-odd coupling, we
investigate the effects of possible scenarios of Lorentz symmetry violation by
electrical and magnetic field configurations on a massive scalar field in this
background, where, analytically, we determine solutions of bound states.",1908.04176v1
2019-08-29,Prospects for Lorentz Invariance Violation searches with top pair production at the LHC and future hadron colliders,"This paper investigates a signature of Lorentz invariance violation with the
$t\bar{t}$ production at the LHC and future hadron colliders. Possible
deviations from the Lorentz symmetry remain poorly constrained in the top quark
sector. With a dedicated analysis of $t\bar{t}$ events produced at the LHC,
bounds in the top sector can be improved by up to three orders of magnitude
relative to Tevatron, the only measurement existing so far. The sensitivity
will be even further enhanced at the HL-LHC and future colliders.",1908.11256v1
2019-10-31,Effects of a Landau-type quantization induced by the Lorentz symmetry violation on a Dirac field,"Inspired by the extension of the Standard Model, we analyzed the effects of
the spacetime anisotropies on a massive Dirac field through a non-minimal
CPT-odd coupling in the Dirac equation, where we proposed a possible scenario
that characterizes the breaking of the Lorentz symmetry which is governed by a
background vector field and induces a Landau-type quantization. Then, in order
to generalize our system, we introduce a hard-wall potential and, for a
particular case, we determine the energy levels in this background. In
addition, at the non-relativistic limit of the system, we investigate the
effects of the Lorentz symmetry violation on thermodynamic aspects of the
system.",1911.00040v1
2019-11-09,Limits on non-minimal Lorentz violating parameters through FCNC and LFV processes,"In this work we analyse a non-minimal Lorentz-violating extension of the
electroweak theory in the fermionic sector. Firstly we analyse the relation
between the CKM rotation in the quark sector and possible contributions of this
new coupling to flavour changing neutral currents (FCNC) processes. In sequel
we look for non-diagonal terms through possible leptonic flavour violation
(LFV) decays. Strong bounds are presented to the Lorentz violating parameters
of both the quark and the leptonic sectors.",1911.03692v2
2019-12-02,Lorentz-symmetry violating physics in a supersymmetric scenario in $(2+1)$-D,"We study the dimensional reduction for a $(3+1)$-dimensional Lorentz
Violating Lagrangian in the matter and gauge sectors in a Supersymmetric
scenario. We thus obtain an effective model for photons induced by the effects
of supersymmetry in our framework with Lorentz-symmetry violating. This model
is discussed in connection with the attainment of a static potential between
charged particles. Our calculation is done within the framework of the
gauge-invariant, but path-dependent variable formalism. We thus find that the
interaction energy displays a screening part, encoded by Bessel functions, and
a linear confining potential.",1912.00523v1
2019-12-13,The MICROSCOPE Space Mission and Lorentz Violation,"In this contribution to the CPT'19 proceedings, we summarize efforts that use
data from the MICROSCOPE space mission to search for Lorentz violation in the
Standard-Model Extension.",1912.07591v1
2019-12-17,The Dirichlet problem of the constant mean curvature equation in Lorentz-Minkowski space and in Euclidean space,"We investigate the differences and similarities of the Dirichlet problem of
the mean curvature equation in the Euclidean space and in the Lorentz-Minkowski
space. Although the solvability of the Dirichlet problem follows standards
techniques of elliptic equations, we focus in showing how the spacelike
condition in the Lorentz-Minkowski space allows to drop the hypothesis on the
mean convexity which is required in the Euclidean case.",1912.07866v1
2020-03-11,Lorentz and permutation invariants of particles I,"A theorem of Weyl tells us that the Lorentz (and parity) invariant
polynomials in the momenta of $n$ particles are generated by the dot products.
We extend this result to include the action of an arbitrary permutation group
$P \subset S_n$ on the particles, to take account of the
quantum-field-theoretic fact that particles can be indistinguishable. Doing so
provides a convenient set of variables for describing scattering processes
involving identical particles, such as $pp \to jjj$, for which we provide an
explicit set of Lorentz and permutation invariant generators.",2003.05487v2
2020-05-28,Top Hadrons in Lorentz-Violating Field Theory,"If there is Lorentz symmetry violation in the $t$ quark sector of the
standard model, changes to particles' dispersion relations might allow for the
existence of stable top-flavored hadrons. Observations of the survival of
high-energy $\gamma$-rays over astrophysical distances can be used to place
one-sided constraints on certain linear combinations of Lorentz violation
coefficients in the $t$ sector at the $\sim 10^{-4}$ level of precision.",2005.14099v1
2020-06-18,Inequalities from Lorentz-Finsler norms,"We show that Lorentz-Finsler geometry offers a powerful tool in obtaining
inequalities. With this aim, we first point out that a series of famous
inequalities such as: the (weighted) arithmetic-geometric mean inequality,
Acz\'el's, Popoviciu's and Bellman's inequalities, are all particular cases of
a reverse Cauchy-Schwarz, respectively, of a reverse triangle inequality
holding in Lorentz-Finsler geometry. Then, we use the same method to prove some
completely new inequalities, including two refinements of Acz\'el's inequality.",2006.10816v2
2020-06-23,Electromagnetic Casimir effect in a Lorentz symmetry violation model,"In this paper, we study the electromagnetic Casimir effects in the context of
Lorentz symmetry violations. Two distinct approaches are considered: the first
one is based on Horava-Lifshitz methodology, which explicitly presents a
space-time anisotropy, while the second is a model that includes
higher-derivatives in the field strength tensor and a preferential direction in
the space-time. We assume that the electromagnetic field obeys the standard
boundary conditions on two large parallel plates. Our main objectives are to
investigate how the Casimir energy and pressure are modified in both Lorentz
violation scenarios.",2006.12924v1
2020-07-29,Time like geodesics in three-dimensional rotating Hořava AdS black hole,"We study the motion of particles in the background of a three-dimensional
rotating Ho\v{r}ava AdS black hole that corresponds to a Lorentz-violating
version of the BTZ black hole and we analyze the effect of the breaking of
Lorentz invariance in such motion by solving analytically the geodesic
equations. Mainly, we find that Lorentz-violating version of the BTZ black hole
posses a more rich geodesic structure, where the planetary and circular orbits
are allowed, which does not occurs in the BTZ background.",2008.00933v2
2020-09-03,Note on stability and microcausality in Lorentz violating antisymmetric tensor field,"The fundamental issues of microcausality and energy positivity conditions are
important to be investigated in the context of spontaneous Lorentz violating
theories. We check the microcausality and energy positivity conditions for a
free rank-2 antisymmetric tensor field with spontaneous Lorentz violating term
and a classically equivalent vector theory from dispersion relations and
propagators, and find that the two theories lead to different conditions. While
the antisymmetric tensor theory satisfies energy positivity condition and can
satisfy microcausality condition for a particular choice of vacuum value, the
vector theory violates both energy positivity and microcausality conditions.",2009.01794v1
2020-09-12,Effects of Lorentz violation in the Bose-Einstein condensation,"In this paper we study the corrections emergent from a Lorentz-violating
CPT-odd extension of the complex scalar sector to the Bose-Einstein
condensation and to the thermodynamics parameters. We initially discussed some
features of the model to only then compute the corrections to the Bose-Einstein
condensation. The calculations were done by computing the generating
functional, from which we extract the thermodynamics parameters. We also
obtained a Lorentz-violating correction for the critical temperature $T_c$ that
sets the Bose-Einstein Condensation.",2009.07034v2
2020-11-05,Quark-sector Lorentz violation in $Z$-boson production,"Quark-sector Lorentz violation is studied in the context of Drell-Yan
dilepton production including effects from Z-boson exchange. We show the chiral
nature of the weak interactions enables parity-violating and spin-dependent
effects to be studied using unpolarized initial states. Constraints are placed
on dimensionless and CPT-even coefficients for Lorentz violation for the first
two generations of quarks using measurements from the Large Hadron Collider.",2011.02632v2
2021-02-18,Isometry Group of Lorentz Manifolds: A Coarse Perspective,"We prove a structure theorem for the isometry group Iso(M, g) of a compact
Lorentz manifold, under the assumption that a closed subgroup has exponential
growth. We don't assume anything about the identity component of Iso(M, g), so
that our results apply for discrete isometry groups. We infer a full
classification of lattices that can act isometrically on compact Lorentz
manifolds. Moreover, without any growth hypothesis, we prove a Tits alternative
for discrete subgroups of Iso(M, g).",2102.09213v1
2021-02-27,Gravitational quantum states as finite representations of the Lorentz group,"A manifestly Lorentz-covariant formulation of Loop Quantum Gravity (LQG) is
given in terms of finite-dimensional representations of the Lorentz group. The
formulation accounts for discrete symmetries, such as parity and time-reversal,
and it establishes a link with Wigner classification of particles. The
resulting quantum model can be seen as LQG with the internal $SU(2)\otimes
SU(2)$ group and it is free of the Immirzi parameter, while the scalar
constraint is just the Euclidean part.",2103.00195v3
2021-03-15,Effects of the CPT-even and Lorentz violation on the Bhabha scattering at finite temperature,"In this paper a Lorentz-violating CPT-even non-minimal coupling term is
considered. A new interaction term between fermions and photons emerges. In
this context, the differential cross-section for Bhabha scattering at finite
temperature is calculated. The temperature effects are introduced using the
Thermo- Field Dynamics (TFD) formalism. It is shown that the differential
cross-section is changed due to both effects, Lorentz violation and finite
temperature.",2103.08404v1
2021-04-04,On plane wave solutions in Lorentz-violating extensions of gravity,"In this paper, we obtain dispersion relations corresponding to plane wave
solutions in various Lorentz-breaking extensions of gravity with dimensions 3,
4, 5 and 6. We demonstrate that these dispersion relations display an usual
Lorentz-invariant mode when the corresponding additive term involves higher
derivatives.",2104.01651v2
2021-04-09,Improved Bounds on Lorentz Symmetry Violation From High-Energy Astrophysical Sources,"Observations of the synchrotron and inverse Compton emissions from
ultrarelativistic electrons in astrophysical sources can reveal a great deal
about the energy-momentum relations of those electrons. They can thus be used
to place bounds on the possibility of Lorentz violation in the electron sector.
Recent $\gamma$-ray telescope data allow the Lorentz-violating electron
$c^{\nu\mu}$ parameters to be constrained extremely well, so that all bounds
are at the level of $7\times 10^{-16}$ or better.",2104.04587v1
2021-05-31,Estimates of the order of approximation of functions of several variables in the generalized Lorentz space,"In this paper we consider $ X(\bar\varphi)$ anisotropic symmetric space $
2\pi$ of periodic functions of $m$ variables, in particular, the generalized
Lorentz space $L_{\bar{\psi},\bar{\tau}}^{*}(\mathbb{T}^{m})$ and
Nikol'skii--Besov's class $S_{X(\bar{\varphi}),\bar{\theta}}^{\bar r}B$. The
article proves an embedding theorem for the Nikol'skii - Besov class in the
generalized Lorentz space and establishes an upper bound for the best
approximations by trigonometric polynomials with harmonic numbers from the
hyperbolic cross of functions from the class
$S_{X(\bar{\varphi}),\bar{\theta}}^{\bar r}B$.",2105.14810v1
2021-06-03,Effects of Lorentz Symmetry Violation on a Relativistic Scalar Particle in Quantum Systems,"In this paper, the relativistic quantum dynamics of a scalar particle under
the effect of Lorentz symmetry violation determined by a tensor
$(K_{F})_{\mu\,\nu\,\alpha\,\beta}$ out of the Standard Model Extension is
investigated. We see that the bound-state solution of the modified Klein-Gordon
equation can be obtained, and the spectrum of energy and the wave function
depends on the Lorentz symmetry breaking parameters",2106.02458v2
2021-06-14,On exact estimates of the order of approximation of functions of several variables in the anisotropic Lorentz-Zygmund space,"In this paper we consider $L_{\overline{p}, \overline\alpha,
\overline{\tau}}^{*}(\mathbb{T}^{m})$ anisotropic Lorentz-Zyg\-mu\-nd space $
2\pi$ of periodic functions of $m$ variables and Nikol'skii--Besov's class
$S_{\overline{p}, \overline\alpha, \overline{\tau}, \bar{\theta}}^{\bar r}B$.
In this paper, we establish order-sharp estimates of the best approximation by
trigonometric polynomials with harmonic numbers from the step hyperbolic cross
of functions from the Nikol'skii - Besov class in the norm of the anisotropic
Lorentz-Zygmund space.",2106.07188v2
2021-06-23,"Statistical properties of Lorentz gases on aperiodic tilings, Part 1","We consider the Lorentz gas model of category A (that is, with no corners and
of finite horizon) on aperiodic repetitive tilings of $\mathbb{R}^2$ of finite
local complexity. We show that the compact factor of the collision map has the
K property, from which we derive mixing for pattern-equivariant functions as
well as the planar ergodicity of the Lorentz gas flow.",2106.12550v2
2021-09-24,One-loop calculations in Lorentz-breaking theories and proper-time method,"We discuss applications of the proper-time method in various minimal Lorentz
violating modifications of QED and present new results obtained with its use.
Explicitly. we calculate the complete one-loop Heisenberg-Euler effective
action involving all orders in $F_{mn}$, for two of the most studied minimal
Lorentz-violating extensions of QED, the one characterized by the axial vector
$b^m$ and the one involving the second-rank constant tensor $c^{mn}$.",2109.11901v2
2021-10-16,Renormalization Scheme Dependence of $β$-Functions In Lorentz-Violating Quantum Field Theory,"Effective quantum field theories that allow for the possibility of Lorentz
symmetry violation can sometimes also include redundancies of description in
their Lagrangians. Explicit calculations in a Lorentz-violating generalization
of Yukawa theory show that when this kind of redundancy exists, different
renormalization schemes may lead to different expressions for the
renormalization group $\beta$-functions, even at only one-loop order. However,
the renormalization group scaling of physically observable quantities appears
not to share this kind of scheme dependence.",2110.08646v2
2021-10-26,Kink scattering in a Lorentz-violating $φ^6$ model,"The role played by a Lorentz-violating term on the outcomes of kink
scattering in the $\phi^6$ model is investigated by using the Fourier spectral
method. Impacts of the Lorentz-violating term on the critical velocities, the
location of two-bounce windows, and the maximal values of various types of
energy densities are analyzed. Some novel features of kink-antikink collisions
are discussed. The interactions between three and four kinks are also
considered.",2110.13381v2
2021-10-26,Spinorial Snyder and Yang Models From Superalgebras And Noncommutative Quantum Superspaces,"The relativistic Lorentz-covariant quantum space-times obtained by Snyder can
be described by the coset generators of (anti) de-Sitter algebras. Similarly,
the Lorentz-covariant quantum phase spaces introduced by Yang, which contain
additionally quantum curved fourmomenta and quantum-deformed relativistic
Heisenberg algebra, can be defined by suitably chosen coset generators of
conformal algebras. We extend such algebraic construction to the respective
superalgebras, which provide quantum Lorentz-covariant superspaces (SUSY Snyder
model) and indicate also how to obtain the quantum relativistic phase
superspaces (SUSY Yang model). In last Section we recall briefly other ways of
deriving quantum phase (super)spaces and we compare the spinorial Snyder type
models defining bosonic or fermionic quantum-deformed spinors.",2110.13697v1
2021-11-05,Maximal and fractional maximal operators in the Lorentz Morrey spaces and their applications to the Bochner Riesz and Schrodinger type operators,"The aim of this paper is to obtain boundedness conditions for the maximal
function Mf and to prove the necessary and sufficient conditions for the
fractional maximal oparator Ma in the Lorentz Morrey spaces which are a new
class of functions. We get our main results by using the obtained sharp
rearrangement estimates. The obtained results are applied to the boundedness of
particular operators such as the Bochner Riesz operator and the Schrodinger
type operators in the Lorentz Morrey spaces, where the nonnegative potential V
belongs to the reverse Holder class.",2111.03732v1
2021-12-22,One-loop Schwinger effect in the presence of Lorentz-violating background fields,"In this work we make use of proper-time method to evaluate Schwinger effect
in the presence of Lorentz-violating background fields. Specifically, we
evaluate the one-loop effective Lagrangian in the presence of Lorentz-violating
time-like vector background $b_\mu$ and pseud-scalar $m_5$ for the pure
electric case. The imaginary part of the effective Lagrangian is computed in
order to calculate the Schwinger effect. Comments on phenomenology are also
performed.",2112.11967v2
2021-12-27,Beta-Decay Spectrum and Lorentz Violation,"Relativity theory and its underlying Lorentz and CPT invariance represent key
principles of physics and therefore require continued experimental scrutiny
across the broadest possible range of energy scales and physical systems.
Possibilities for tests of these symmetries in precision $\beta$-decay
experiments with focus on KATRIN are investigated. It is found that
countershaded departures from relativity, which represent a particular
challenge to detection, are accessible in such experiments. In this context, it
is argued that KATRIN would be in an excellent position to conduct the
first-ever experimental search for countershaded Lorentz and CPT breaking in
neutrinos.",2112.13803v1
2022-01-17,Can Quantum Nonlocality be the Consequence of Faster-Than-Light Interactions?,"It has been advocated by Bell and Bohm that the Einstein-Podolsky-Rosen (EPR)
correlations are mediated through faster-than-light (FTL) interactions. In a
previous paper a way to avoid causal paradoxes derived from this FTL hypothesis
(via the breakdown of Lorentz symmetry) has been suggested. Lorentz
transformations would remain valid, but there would be no equivalence between
active and passive Lorentz transformations in the case of EPR correlations.
Some counterintuitive consequences of this assumption are briefly examined
here.",2201.06420v4
2022-02-07,Supertranslation-Invariant Dressed Lorentz Charges,"We present an explicit formula for Lorentz boosts and rotations that commute
with BMS supertranslations in asymptotically flat spacetimes. Key to the
construction is the use of infrared regularizations and of a unitary
transformation that makes observables commute with the soft degrees of freedom.
We explicitly verify that our charges satisfy the Lorentz algebra and we check
that they are consistent with expectations by evaluating them on the
supertranslated Minkowski space and on the boosted Kerr black hole.",2202.03442v2
2022-02-25,Casimir effect and Lorentz invariance violation,"The Casimir effect is one of the most direct manifestations of the existence
of the vacuum quantum fluctuations, discovered by H. B Casimir in 1948. On the
other hand, Lorentz invariance is one of the main and basic concepts in special
relativity, which states that, the laws of physics are invariant under Lorentz
transformation. In this work, we calculate the corrections imposed by LIV on
Casimir effect (force). This may provide a direct probe to test LIV in nature.",2203.01812v1
2022-03-14,The dual spaces of variable anisotropic Hardy-Lorentz spaces and continuity of a class of linear operators,"In this paper, the author obtain the continuity of a class of linear
operators on variable anisotropic Hardy-Lorentz spaces.
  In addition, the author also obtain that the dual space of variable
anisotropic Hardy-Lorentz spaces is the anisotropic BMO-type spaces with
variable exponents.
  This result is still new even when the exponent function $p(\cdot)$ is $p$.",2203.06838v2
2022-03-20,Some examples of equivalent rearrangement-invariant quasi-norms defined via f* or f**,"We consider Lorentz-Karamata spaces, small and grand Lorentz-Karamata spaces,
and the so-called $\mathcal{L}$, $\mathcal{R}$, $\mathcal{LL}$, $\mathcal{RL}$,
$\mathcal{RL}$, and $\mathcal{RR}$ spaces. The quasi-norms for a function $f$
in each of these spaces can be defined via the non-increasing rearrangement
$f^*$ or via the maximal function $f^{**}$. We investigate when these
quasi-norms are equivalent. Most of the proofs are based on Hardy-type
inequalities. As application we demonstrate how our general results can be used
to establish interpolation formulae for the grand and small Lorentz-Karamata
spaces.",2203.10500v1
2022-03-31,Rigidity and Parallelism in the spacetime,"The effect of the linear-fractional transformations on the parallel lines in
the spacetime has been studied. Fock-Lorentz transformations maps a line to a
line, from which one can obtain the combinations rule for the velocities in the
Fock-Lorentz transformations. Rigidity is defined as a consequences of holding
parallelism under the transformations. The Fock-Lorentz transformations do not
preserve rigidity, which leads to some novel results such as growing distances
alongside with advancing time. Also, it is shown that the time coordinates of
events will come closer to each other in the transformed coordinates by going
back in time",2204.00109v1
2022-04-15,Parton distributions: Functional complexity and Lorentz parametrization,"In the paper we focus on the study of the functional complexity of the
Lorentz parametrizing functions in connection with the time-reversal
transformations. We argue that the interactions encoded in the corresponding
correlators of non-local quark(-gluon) operators generate additional sources of
functional complexity for the parametrizing functions which are not discussed
in the literature. We also revisit the Lorentz parametrization of different
correlators given by the hadron matrix elements of the non-local operators. The
evidences for the new parametrizing function existence have been presented.",2204.07510v1
2022-05-19,The Mass Hyperboloid as a Poisson-Lie Group,"The light cone formalism of a massive scalar field has been shown by Dirac to
have many advantages. But it is not manifestly Lorentz invariant. We will show
that this is a feature not a bug: Lorentz invariance is indeed a symmetry, but
in a different sense defined by Drinfel'd. The key idea is that the mass shell
(mass hyperboloid) is a Poisson-Lie group: there is a non-abelian group
multiplication and non-zero Poisson brackets between components of
four-momentum. Rotations form the dual group of the hyperboloid in the sense of
Drinfel'd. Infinitesimal Lorentz transformations form a Lie bi-algebra.",2205.09468v1
2022-06-20,Topological and topological linear properties of the Sugeno-Lorentz spaces,"The properties of the spaces of Sugeno integrable functions are quite
different from those of the ordinary spaces of Lebesgue integrable functions.
The purpose of the paper is to further advance our study of the Sugeno-Lorentz
spaces, in which the completeness and separability of the spaces were
discussed. As a continuation of our previous research, in this paper, some
fundamental topological and topological linear properties of the Sugeno-Lorentz
spaces are investigated in detail.",2206.09673v2
2022-07-05,Recent experimental progress on probing Lorentz Violation in pure gravity for d=6,"Short-range experiment with striped design of the test and source masses
offers uniquely sensitive probes for Lorentz Violation. In our previous work,
we proposed to combine the horizontally and vertically striped experiments to
constrain the violating parameters. Here, we further point out adopting the
vertically striped structure with the experimental setup placed at two azimuth
angles, which has more experimental operability. For the experiment, we have
completed the assembly and measurement of the torsion pendulum.",2207.01853v1
2022-07-10,Electromagnetic Flavor-Changing Lepton Decays from Lorentz and CPT Violation,"Lorentz- and CPT-violating effects initiating two-body electromagnetic
flavor-changing decays of charged leptons are studied in the framework of
Lorentz-violating effective field theory. An analysis of data from experiments
at the Paul Scherrer Institute and at the Stanford Linear Accelerator measuring
the branching ratios of these decays provides 576 constraints on independent
flavor-changing effects in the charged-lepton sector, consistent with no
Lorentz and CPT violation at the level of parts in $10^{-13}$ GeV$^{-1}$ to
$10^{-9}$ GeV$^{-1}$.",2207.04545v1
2022-08-11,Pati-Salam model in curved space-time and sheaf quantization,"This note aims to give a self-contain and detail explanation about U(k')times
U(k) Pati-Salam model in curved space-time which derived from (1+n)-dimensional
square root Lorentz manifold by self-parallel transportation principle. The
concepts foundation of manifold from view point of category theory, fiber
bundle and sheaf theories are reviewed. There are extra U(k')times
U(k)-principal bundle and U(k)-associated bundle than (1+n)-dimensional Lorentz
manifold. The conservative currents on square root Lorentz manifold are
discussed preliminary. A detail proof of relation from sheaf quantization to
path integral quantization is given.",2208.05942v2
2022-08-12,Simulated Lorentz Force Detuning Compensation With A Double Lever Tuner On A Dressed ILC/1.3 GHZ Cavity At Room Temperature,"Pulsed SRF linacs with high accelerating gradients experience large frequency
shifts caused by Lorentz force detuning (LFD). A piezoelectric actuator with a
resonance control algorithm can maintain the cavity frequency at the nominal
level, thus reducing the RF power. This study uses a double lever tuner with a
piezoelectric actuator for compensation and another piezoelectric actuator to
simulate the effects of the Lorentz force pulse. A double lever tuner has an
advantage by increasing the stiffness of the cavity-tuner system, thus reducing
the impact of LFD. The tests are conducted at room temperature and with a
dressed 1.3 GHz 9-cell cavity.",2208.06286v1
2022-08-31,On the Lorentz symmetry in conformally reduced Quantum Gravity,"The functional renormalization group treatment of the conform reduced
Einstein-Hilbert gravity is extended by following the evolution of the time and
space derivatives separately, in order to consider the Lorentz symmetry during
the evolution. We found the Reuter fixed point in the ultraviolet region. It is
shown that starting from the Gaussian fixed point the Lorentz symmetry breaks
down in the vicinity of the Reuter fixed point. Similarly, in the symmetry
broken phase it also breaks down in the infrared region close to a critical
singularity scale. By calculating the anomalous dimension form the kinetic term
of the action, we found a new relevant coupling belonging to the curvature.",2208.14710v1
2022-09-13,Single-Particle Quantum Mechanics of the Free Klein-Gordon Equation with Lorentz Violation,"In spite of its problems with interactions, the first-quantized Klein-Gordon
equation is a satisfactory theory of free spinless particles. Moreover, the
usual theory may be extended to describe Lorentz-violating behavior, of the
same types that exist can in second-quantized scalar field theories. However,
because the construction of the theory requires a restriction to
positive-energy modes, the Hilbert space inner product and the position
operator depend explicitly on the form of the Lorentz violation.",2209.06093v1
2022-09-26,Li-Yorke Chaos for Composition operators on Orlicz-Lorentz spaces,"In this paper, we study the Li-Yorke chaotic composition operators on
Orlicz-Lorentz space. In fact, necessary and sufficient conditions are given
for Li-Yorke chaotic composition operator $C_{\tau}$ on
$\mathbb{L}^{\varphi,h}(\mu)$. Further, we present the equivalent conditions
for $C_{\tau}$ to be Li-Yorke chaotic. This paper's results are the
generalization of results of [15] into Orlicz-Lorentz spaces.",2209.12989v2
2022-11-09,Null boundary gravitational charges from local Lorentz symmetries,"In this paper, we revisit the null boundary gravitational charge in the
Newman-Penrose formalism with special emphasis on the charges from local
Lorentz transformations. We find that there is one more charge derived from the
local Lorentz transformation and the new charge is purely from the Holst term.
This reveals a remarkable fact that trivial terms which do not change classical
equations of motion can not only affect the boundary degrees of freedom through
their contributions to the boundary charges but also have their own rights to
create new boundary degrees of freedom.",2211.04736v1
2022-11-17,The change in the direction of the electric field using the Lorentz-type transformation,"In the present work, we will derive the expression for the change in
direction of the electric field using the Lorentz transformation for inertial
frame or un-accelerated frame. The acceleration also influences the observed
rate of a moving clock in addition to the influence due to its velocity. So we
will also derive the expression for the change in direction of the electric
field using the Lorentz-type transformation (as given by Friedman) for
non-inertial frame or uniformly accelerated frame.",2211.10417v1
2022-11-22,Lorentz-breaking Rarita-Schwinger model,"In this paper, we formulate the Lorentz-breaking extension for the spin-3/2
field theory and couple it to the Abelian gauge field in a Lorentz violating
(LV) manner. Next, we calculate the lower LV quantum corrections, that is, the
Carroll-Field-Jackiw (CFJ) term, which, being superficially divergent, turns
out to be finite but ambiguous, and also the higher-derivative CFJ term.
Besides, we compute the aether term, being the lowest CPT-even LV term,
involving the second order in the LV vector.",2211.12414v2
2022-12-13,The Boltzmann equation and equilibrium thermodynamics in Lorentz-violating theories,"In this work we adapt the foundations of relativistic kinetic theory and the
Boltzmann equation to particles with Lorentz-violating dispersion relations.
The latter are taken to be those associated to two commonly considered sets of
coefficients in the minimal Standard-Model Extension. We treat both the cases
of classical (Maxwell-Boltzmann) and quantum (Fermi-Dirac and Bose-Einstein)
statistics. It is shown that with the appropriate definition of the entropy
current, Boltzmann's H-theorem continues to hold. We derive the equilibrium
solutions and then identify the Lorentz-violating effects for various
thermodynamic variables, as well as for Bose-Einstein condensation. Finally, a
scenario with non-elastic collisions between multiple species of particles
corresponding to chemical or nuclear reactions is considered.",2212.06528v1
2022-12-14,Cosmology in symmetric teleparallel bumblebee gravity,"Symmetric teleparallel gravity (STG) is an alternative description of the
gravitational field as an effect of the nonmetricity rather than the curvature
of the spacetime. For an specific choice of the symmetric teleparallel
lagrangian, the STG dynamics is equivalent to the general relativity (GR), and
it is called Symmetric teleparallel equivalent to general relativity (STEGR).
We propose a local Lorentz violating dynamics in the gravitational sector in
the STEGR framework. The Lorentz violation is trigged by the vacuum expectation
value (vev) of the well-known bumblebee field, whose vev couples to the
nonmetricity tensor. The effects of such couplings on the cosmological
evolution is investigated.",2212.07167v1
2023-01-17,Search for CPT and Lorentz Invariance Violation in the Muon g-2 Experiment at Fermilab,"Muon g-2 data can be used to study sidereal variation of anomalous muon
precession rate, which is one of the important signatures of CPT and Lorentz
invariance violation. The discussion in this proceeding will focus on the
framework which has been used to study sidereal variation of anomalous muon
precession rate in Muon g-2 Run 2 data. Also, a brief introduction will be
given about the blinding framework which will be used on Run 2/3 data of Muon
g-2 experiment. This blinding framework will keep the actual result of the
experiment masked from the analyzer during the analysis process.",2301.07571v2
2023-02-17,On Weighted Lorentz-Sobolev estimates of obstacle problems for fully nonlinear elliptic equations under relaxed convexity assumptions with oblique boundary,"In this work, we will study estimates for the Hessian of viscosity solutions
of obstacle-type problems with oblique boundary conditions where and governed
by fully nonlinear elliptic operators under conditions of weakened convexity in
the context of weighted Lorentz spaces. Our approach goes through weighetd
Lorentz-Sobolev estimates up to boundary for the associate oblique boundary
condition with problem without obstacles and convexity in the governing
operator.",2302.09177v2
2023-05-18,On the nonlinear electrodynamics in a Lorentz-breaking scenario,"In this work, we study a model in nonlinear electrodynamics in the presence
of a CPT-even term that violates Lorentz symmetry. The Lorentz-breaking vector,
in addition to the usual background magnetic field, produces interesting
effects in the dispersion relations. The consequences on the vacuum refractive
index and the group velocity are studied. Vacuum birefringence is discussed in
the case the nonlinear electrodynamics is a Euler-Heisenberg model.",2305.10914v3
2023-06-01,Cosmology in the Lorentz gauge theory,"This proceeding is an introduction to cosmological applications of the
Lorentz gauge theory. It provides the ingredients for a unique, though yet
tentative $\Lambda$CDM theory of cosmology. The emergence of spacetime is
described by the spontaneous symmetry breaking called here the khronogenesis.
Space is then associated with the field strength of the antiself-dual gauge
potential, and gravity is associated with the self-dual field strength. In the
cosmological setting, khronogenesis seems to predict inflation. It is shown
that the Lorentz gauge theory allows the consistent description of spin
currents which could have important roles in cosmological phenomenology.",2306.00963v2
2023-06-28,Fermionic quantum gas at finite temperature within a Lorentz violating background,"In this work we consider a fermionic quantum gas within a Lorentz-Violating
background at finite temperature. We derive the effective action within Path
Integral formalism considering the interaction of external electromagnetic
field and Lorentz violating background fields with quantum fermions. To
introduce the temperature effects, we employ the Matsubara formalism. Comments
about the corresponding phenomenology are also made.",2306.16511v1
2023-07-10,Casimir effect of Lorentz-violating charged Dirac in background magnetic field,"We study the effect of the Lorentz symmetry breaking on the Casimir energy of
charged Dirac in the presence of a uniform magnetic field. We use the boundary
condition from the MIT bag model to represent the property of the plates. We
investigate two cases of the direction of violation, namely, time-like and
space-like vector cases. We discuss how the Lorentz violation and the magnetic
field affect the structure of the Casimir energy and its pressure. We also
investigate the weak and strong magnetic field cases with two different limits,
heavy and light masses.",2307.04448v1
2023-10-04,Lorentz invariants of pure three-qubit states,"Extending the mathematical framework of Phys. Rev. A 102, 052419 (2020) we
construct Lorentz invariant quantities of pure three-qubit states. This method
serves as a bridge between the well-known local unitary (LU) invariants viz.
concurrences and three-tangle of an arbitrary three-qubit pure state and the
Lorentz invariants of its reduced two-qubit systems.",2310.02900v1
2023-10-24,Two-loop corrections to the Carroll-Field-Jackiw term in a CPT-odd Lorentz-violating scalar QED,"In this study, we systematically calculate one-loop corrections to the
Lorentz-violating vertices within the framework of CPT-odd Quantum
Electrodynamics, encompassing scalar and photon fields in arbitrary gauge.
Additionally, we ascertain the finite two-loop corrections to the
Carroll-Field-Jackiw term. Furthermore, we analyze the UV divergent component
of the two-loop Lorentz-violating correction in the self-energy of the scalar
field.",2310.15715v2
2023-11-10,Poincare group spin networks,"Spin network technique is usually generalized to relativistic case by
changing $SO(4)$ group -- Euclidean counterpart of the Lorentz group -- to its
universal spin covering $SU(2)\times SU(2)$, or by using the representations of
$SO(3,1)$ Lorentz group. We extend this approach by using inhomogeneous Lorentz
group $\mathcal{P}=SO(3,1)\rtimes \mathbb{R}^4$, which results in the
simplification of the spin network technique. The labels on the network graph
corresponding to the subgroup of translations $\mathbb{R}^4$ make the
intertwiners into the products of $SU(2)$ parts and the energy-momentum
conservation delta functions. This maps relativistic spin networks to usual
Feynman diagrams for the matter fields.",2311.06328v2
2023-11-28,A note on extreme points of the unit of Hardy-Lorentz spaces,"We show that inner functions are extreme points of the unit ball of the
Hardy-Lorentz space $H(\Lambda(\varphi))$, for $\Lambda(\varphi)$ a Lorentz
space with $\varphi$ strictly increasing and strictly concave.",2311.16606v3
2023-12-13,Non-analyticity of the $S$-matrix with spontaneously broken Lorentz invariance,"We study the $S$-matrix of Goldstones in the renormalizable theory of a
$U(1)$ complex scalar at finite charge, i.e. in a state that breaks Lorentz
invariance. The theory is weakly coupled so that this $S$-matrix exists at all
energies. Unlike the Lorentz invariant case, the resulting $S$-matrix is not
analytic in the exchanged (complexified) four-momentum. The non-analyticities
stem from the LSZ reduction formula, as a consequence of the energy-dependent
mixing between the radial and Goldstone modes.",2312.08441v1
2023-12-26,Neutrino Lorentz Invariance Violation from Cosmic Fields,"From a cosmological perspective, scalar fields are well motivated dark matter
and dark energy candidates. Several possibilities of neutrino couplings with a
time-varying cosmic field have been investigated in the literature. In this
work, we present a framework in which violations of Lorentz invariance (LIV)
and $CPT$ symmetry in the neutrino sector could arise from an interaction among
neutrinos with a time-varying scalar field. Furthermore, some cosmological and
phenomenological aspects and constraints concerning this type of interaction
are discussed. Potential violations of Lorentz and $CPT$ symmetries at present
and future neutrino oscillation experiments such as IceCube and KM3NeT can
probe this scenario.",2312.16320v2
2024-01-16,The central limit theorem for the free path length of the periodic Lorentz gas in the Boltzmann-Grad limit,"We prove the central limit theorem for the free path length of the periodic
Lorentz gas in the Boltzmann-Grad limit. Our proof relies on the connection
between the distribution of the free path length of the periodic Lorentz gas
and the expanding translates of a unipotent subgroup on the lattice space,
which was described in the seminal works of Marklof-Str\""ombergsson. Moreover,
we obtain the asymptotic formula of the distribution function of the free path
length and also derive the central limit theorem for the counting function in
the related lattice problem.",2401.08158v1
2024-02-07,Characterization of the weak-type boundedness of the Hilbert transform on weighted Lorentz spaces,"We characterize the weak-type boundedness of the Hilbert transform $H$ on
weighted Lorentz spaces $\Lambda^p_u(w)$, with $p>0$, in terms of some
geometric conditions on the weights $u$ and $w$ and the weak-type boundedness
of the Hardy-Littlewood maximal operator on the same spaces. Our results
recover simultaneously the theory of the boundedness of $H$ on weighted
Lebesgue spaces $L^p(u)$ and Muckenhoupt weights $A_p$, and the theory on
classical Lorentz spaces $\Lambda^p(w)$ and Ari\~no Muckenhoupt weights $B_p$.",2402.04877v1
2024-02-07,Boundedness of the Hilbert transform on weighted Lorentz spaces,"We study the boundedness of the Hilbert transform $H$ and the Hilbert maximal
operator $H^*$ on weighted Lorentz spaces $\Lambda^p_u(w)$. We start by giving
several necessary conditions that, in particular, lead us to the complete
characterization of the weak-type boundedness of both $H$ and $H^*$, whenever
$u\in A_1$. For the strong-type case, we also get the characterization of both
operators when $p>1$. Applications to the case of Lorentz spaces $L^{p,q}(u)$
are presented.",2402.05299v1
2024-02-07,Lorentz-Shimogaki and Boyd theorems for weighted Lorentz spaces,"We prove the Lorentz-Shimogaki and Boyd theorems for the spaces
$\Lambda^p_u(w)$. As a consequence, we give the complete characterization of
the strong boundedness of $H$ on these spaces in terms of some geometric
conditions on the weights $u$ and $w$, whenever $p>1$. For these values of $p$,
we also give the complete solution of the weak-type boundedness of the
Hardy-Littlewood operator on $\Lambda^p_u(w)$.",2402.05304v1
2024-02-08,Weak Type Boundedness of the Hardy Littlewood Maximal Operator on Weighted Lorentz Spaces,"The main goal of this paper is to provide a complete characterization of the
weak-type boundedness of the Hardy-Littlewood maximal operator, $M$, on
weighted Lorentz spaces $\Lambda^p_u(w)$, whenever $p>1$. This solves a problem
left open in \cite{crs:crs}. Moreover, with this result, we complete the
program of unifying the study of the boundedness of $M$ on weighted Lebesgue
spaces and classical Lorentz spaces, which was initiated in the aforementioned
monograph.",2402.05464v1
2024-03-07,The Power of Lorentz Quantum Computer,"We demonstrate the superior capabilities of the recently proposed Lorentz
quantum computer (LQC) compared to conventional quantum computers. We introduce
an associated computational complexity class, bounded-error Lorentz quantum
polynomial-time (BLQP), and prove that the complexity class ${\text P}^{\sharp
\text{P}}$ is contained within BLQP. We present LQC algorithms that solve in
polynomial time the problem of maximum independent set and the problems in the
classes of NP, co-NP, PH (polynomial hierarchy), PP (probabilistic
polynomial-time), and ${\text P}^{\sharp \text{P}}$. We show that the quantum
computing with postselection proposed by Aaronson can be simulated efficiently
by LQC, but not vice versa.",2403.04170v1
2004-07-28,Stability of hydrodynamical relativistic planar jets. II. Long-term nonlinear evolution,"In this paper we continue our study of the Kelvin-Helmholtz (KH) instability
in relativistic planar jets following the long-term evolution of the numerical
simulations which were introduced in Paper I. The models have been classified
into four classes (I to IV) with regard to their evolution in the nonlinear
phase, characterized by the process of jet/ambient mixing and momentum
transfer. Models undergoing qualitatively different non-linear evolution are
clearly grouped in well-separated regions in a jet Lorentz
factor/jet-to-ambient enthalpy diagram. Jets with a low Lorentz factor and
small enthalpy ratio are disrupted by a strong shock after saturation. Those
with a large Lorentz factor and enthalpy ratio are unstable although the
process of mixing and momentum exchange proceeds to a longer time scale due to
a steady conversion of kinetic to internal energy in the jet. In these cases,
the high value of the initial Lorentz seems to prevent transversal velocity
from growing far enough to generate the strong shock that breaks the slower
jets. Finally, jets with either high Lorentz factors and small enthalpy ratios
or low Lorentz factors and large enthalpy ratios appear as the most stable.",0407574v1
2005-04-04,Parameters of the prompt gamma-ray burst emission estimated with the opening angle of jets,"We present in this paper an approach to estimate the initial Lorentz factor
of gamma-ray bursts (GRBs) without referring to the delayed emission of the
early afterglow. Under the assumption that the afterglow of the bursts
concerned occurs well before the prompt emission dies away, the Lorentz factor
measured at the time when the duration of the prompt emission is ended could be
estimated by applying the well-known relations of GRB jets. With the concept of
the efficiency for converting the explosion energy to radiation, this Lorentz
factor can be related to the initial Lorentz factor of the source. The
corresponding rest frame peak energy can accordingly be calculated. Applying
this method, we estimate the initial Lorentz factor of the bulk motion and the
corresponding rest frame spectral peak energy of GRBs for a new sample where
the redshift and the break time in the afterglow are known. Our analysis shows
that, in the circumstances, the initial Lorentz factor of the sample would peak
at 200 and would be distributed mainly within $(100,400)$, and the peak of the
distribution of the corresponding rest frame peak energy would be $0.8keV$ and
its main region would be $(0.3keV,3keV)$.",0504070v3
2006-01-20,"Opening angles, Lorentz factors and confinement of X-ray binary jets","We present a collation of the available data on the opening angles of jets in
X-ray binaries, which in most cases are small (less than 10 degrees). Under the
assumption of no confinement, we calculate the Lorentz factors required to
produce such small opening angles via the transverse relativistic Doppler
effect. The derived Lorentz factors, which are in most cases lower limits, are
found to be large, with a mean greater than 10, comparable to those estimated
for AGN and much higher than the commonly-assumed values for X-ray binaries of
2 to 5. Jet power constraints do not in most cases rule out such high Lorentz
factors. The upper limits on the opening angles show no evidence for smaller
Lorentz factors in the steady jets of Cygnus X-1 and GRS 1915+105. In those
sources in which deceleration has been observed (notably XTE J1550-564 and
Cygnus X-3), some confinement of the jets must be occurring, and we briefly
discuss possible confinement mechanisms. It is however possible that all the
jets could be confined, in which case the requirement for high bulk Lorentz
factors can be relaxed.",0601482v1
2004-05-17,About Lorentz invariance in a discrete quantum setting,"A common misconception is that Lorentz invariance is inconsistent with a
discrete spacetime structure and a minimal length: under Lorentz contraction, a
Planck length ruler would be seen as smaller by a boosted observer. We argue
that in the context of quantum gravity, the distance between two points becomes
an operator and show through a toy model, inspired by Loop Quantum Gravity,
that the notion of a quantum of geometry and of discrete spectra of geometric
operators, is not inconsistent with Lorentz invariance. The main feature of the
model is that a state of definite length for a given observer turns into a
superposition of eigenstates of the length operator when seen by a boosted
observer. More generally, we discuss the issue of actually measuring distances
taking into account the limitations imposed by quantum gravity considerations
and we analyze the notion of distance and the phenomenon of Lorentz contraction
in the framework of ``deformed (or doubly) special relativity'' (DSR), which
tentatively provides an effective description of quantum gravity around a flat
background. In order to do this we study the Hilbert space structure of DSR,
and study various quantum geometric operators acting on it and analyze their
spectral properties. We also discuss the notion of spacetime point in DSR in
terms of coherent states. We show how the way Lorentz invariance is preserved
in this context is analogous to that in the toy model.",0405085v1
1998-09-24,Lorentz-Violating Extension of the Standard Model,"In the context of conventional quantum field theory, we present a general
Lorentz-violating extension of the minimal SU(3) x SU(2) x U(1) standard model
including CPT-even and CPT-odd terms. It can be viewed as the low-energy limit
of a physically relevant fundamental theory with Lorentz-covariant dynamics in
which spontaneous Lorentz violation occurs. The extension has gauge invariance,
energy-momentum conservation, and covariance under observer rotations and
boosts, while covariance under particle rotations and boosts is broken. The
quantized theory is hermitian and power-counting renormalizable, and other
desirable features such as microcausality, positivity of the energy, and the
usual anomaly cancellation are expected. Spontaneous symmetry breaking to the
electromagnetic U(1) is maintained, although the Higgs expectation is shifted
by a small amount relative to its usual value and the $Z^0$ field acquires a
small expectation. A general Lorentz-breaking extension of quantum
electrodynamics is extracted from the theory, and some experimental tests are
considered. In particular, we study modifications to photon behavior. One
possible effect is vacuum birefringence, which could be bounded from
cosmological observations by experiments using existing techniques. Radiative
corrections to the photon propagator are examined. They are compatible with
spontaneous Lorentz and CPT violation in the fermion sector at levels suggested
by Planck-scale physics and accessible to other terrestrial laboratory
experiments.",9809521v1
1998-09-25,CPT and Lorentz Tests in Penning Traps,"A theoretical analysis is performed of Penning-trap experiments testing CPT
and Lorentz symmetry through measurements of anomalous magnetic moments and
charge-to-mass ratios. Possible CPT and Lorentz violations arising from
spontaneous symmetry breaking at a fundamental level are treated in the context
of a general extension of the SU(3) x SU(2) x U(1) standard model and its
restriction to quantum electrodynamics. We describe signals that might appear
in principle, introduce suitable figures of merit, and estimate CPT and Lorentz
bounds attainable in present and future Penning-trap experiments. Experiments
measuring anomaly frequencies are found to provide the sharpest tests of CPT
symmetry. Bounds are attainable of approximately $10^{-20}$ in the
electron-positron case and of $10^{-23}$ for a suggested experiment with
protons and antiprotons. Searches for diurnal frequency variations in these
experiments could also limit certain types of Lorentz violation to the level of
$10^{-18}$ in the electron-positron system and others at the level of
$10^{-21}$ in the proton-antiproton system. In contrast, measurements comparing
cyclotron frequencies are sensitive within the present theoretical framework to
different kinds of Lorentz violation that preserve CPT. Constraints could be
obtained on one figure of merit in the electron-positron system at the level of
$10^{-16}$, on another in the proton-antiproton system at $10^{-24}$, and on a
third at $10^{-25}$ using comparisons of $H^-$ ions with antiprotons.",9809543v1
2001-05-02,Lorentz Group in Feynman's World,"R. P. Feynman was quite fond of inventing new physics. It is shown that some
of his physical ideas can be supported by the mathematical instruments
available from the Lorentz group. As a consequence, it is possible to construct
a Lorentz-covariant picture of the parton model. It is shown first how the
Lorentz group can be used for studying the internal space-time symmetries of
relativistic particles. These symmetries are dictated by Wigner's little
groups, whose transformations leave the energy-momentum four-vector of a given
particle invariant. The symmetry of massive particles is like the
three-dimensional rotation group, while the symmetry of massless particles is
locally isomorphic to the two-dimensional Euclidean group. It is noted that the
E(2)-like symmetry of massless particles can be obtained as an
infinite-momentum and/or zero-mass limit of the O(3)-like little group for
massive particles. It is shown that the formalism can be extended to cover
relativistic particles with space-time extensions, such as heavy ions and
hadrons in the quark model. It is possible to construct representations of the
little group using harmonic oscillators, which Feynman et al. used for studying
relativistic extended hadrons. This oscillator formalism allows us to show that
Feynman's parton model is a Lorentz-boosted quark model. The formalism also
allows us to explain in detail Feynman's rest of the universe which is
contained in his parton picture.",0105019v1
2005-06-06,Lorentz Violation in Extra Dimensions,"In theories with extra dimensions it is well known that the Lorentz
invariance of the $D=4+n$-dimensional spacetime is lost due to the compactified
nature of the $n$ dimensions leaving invariance only in 4d. In such theories
other sources of Lorentz violation may exist associated with the physics that
initiated the compactification process at high scales. Here we consider the
possibility of capturing some of this physics by analyzing the higher
dimensional analog of the model of Colladay and Kostelecky. In that scenario a
complete set of Lorentz violating operators arising from spontaneous Lorentz
violation, that are not obviously Planck-scale suppressed, are added to the
Standard Model action. Here we consider the influence of the analogous set of
operators which break Lorentz invariance in 5d within the Universal Extra
Dimensions picture. We show that such operators can greatly alter the
anticipated Kaluza-Klein(KK) spectra, induce electroweak symmetry breaking at a
scale related to the inverse compactification radius, yield sources of parity
violation in, e.g., 4d QED/QCD and result in significant violations of
KK-parity conservation produced by fermion Yukawa couplings, thus destabilizing
the lightest KK particle. LV in 6d is briefly discussed.",0506056v2
1996-08-07,Convection displacement current and alternative form of Maxwell-Lorentz equations,"Some mathematical inconsistencies in the conventional form of Maxwell's
equations extended by Lorentz for a single charge system are discussed. To
surmount these in framework of Maxwellian theory, a novel convection
displacement current is considered as additional and complementary to the
famous Maxwell displacement current. It is shown that this form of the
Maxwell-Lorentz equations is similar to that proposed by Hertz for
electrodynamics of bodies in motion. Original Maxwell's equations can be
considered as a valid approximation for a continuous and closed (or going to
infinity) conduction current. It is also proved that our novel form of the
Maxwell-Lorentz equations is relativistically invariant. In particular, a
relativistically invariant gauge for quasistatic fields has been found to
replace the non-invariant Coulomb gauge. The new gauge condition contains the
famous relationship between electric and magnetic potentials for one uniformly
moving charge that is usually attributed to the Lorentz transformations. Thus,
for the first time, using the convection displacement current, a physical
interpretation is given to the relationship between the components of the
four-vector of quasistatic potentials. A rigorous application of the new gauge
transformation with the Lorentz gauge transforms the basic field equations into
an independent pair of differential equations responsible for longitudinal and
transverse fields, respectively. The longitudinal components can be interpreted
exclusively from the standpoint of the instantaneous ""action at a distance""
concept and leads to necessary conceptual revision of the conventional
Faraday-Maxwell field. The concept of electrodynamic dualism is proposed for
self-consistent classical electrodynamics. It implies simultaneous coexistence",9608038v1
2008-11-26,"Doppler factors, Lorentz factors and viewing angles for quasars, BL Lacertae objects and radio galaxies","We have calculated variability Doppler boosting factors, Lorentz factors, and
viewing angles for a large sample of sources by using total flux density
observations at 22 and 37 GHz and VLBI data. We decomposed the flux curves into
exponential flares and determined the variability brightness temperatures of
the fastest flares. By assuming the same intrinsic brightness temperature for
each source, we calculated the Doppler boosting factors for 87 sources. In
addition we used new apparent jet speed data to calculate the Lorentz factors
and viewing angles for 67 sources. We find that all quasars in our sample are
Doppler-boosted and that the Doppler boosting factors of BL Lacertae objects
are lower than of quasars. The new Lorentz factors are about twice as high as
in earlier studies, which is mainly due to higher apparent speeds in our
analyses. The jets of BL Lacertae objects are slower than of quasars. There are
some extreme sources with very high derived Lorentz factors of the order of a
hundred. These high Lorentz factors could be real. It is also possible that the
sources exhibit such rapid flares that the fast variations have remained
undetected in monitoring programmes, or else the sources have a complicated jet
structure that is not amenable to our simple analysis. Almost all the sources
are seen in a small viewing angle of less than 20 degrees. Our results follow
the predictions of basic unification schemes for AGN.",0811.4278v1
2011-03-29,Ternary relative velocity; astonishing conflict of the Lorentz group with relativity,"We are proving that the Lorentz boost entails the relative velocity to be
ternary: ternary relative velocity is a velocity of a body with respect to an
interior observer as seen by a preferred exterior-observer. The Lorentz boosts
imply non-associative addition of ternary relative velocities. Within
Einstein's special relativity theory, each preferred observer (fixed stars,
aether, etc), determine the unique relative velocity among each pair of massive
bodies. Therefore, the special relativity founded on Minkowski's axiom, that
each pair of reference systems must be related by Lorentz isometry, needs a
preferred reference system in order to have the unique Einstein's relative
velocity among each pair of massive bodies. This choice-dependence of relative
velocity violate the Relativity Principle that all reference systems must be
equivalent. This astonishing conflict of the Lorentz relativity group, with the
Relativity Principle, can be resolved in two alternative ways. Either, abandon
the Relativity Principle in favor of a preferred reference system [de Abreu
2004; de Abreu and Guerra 2005, 2006]. Or, within the Relativity Principle,
replace the Lorentz relativity group by the relativity groupoid, with the
choice-free binary relative velocities introduced by Minkowski in 1908. Binary
- means that the relative velocity is a function of a pair of reference
systems. Following Minkowski [1908], we consider the binary relative velocity
to be the Minkowski space-like vector (and not the Minkowski bivector as it is
in the Hestenes theory [Hestenes 1974]).",1104.0682v1
2011-08-19,A Lorentz-Violating Alternative to Higgs Mechanism?,"We consider a four-dimensional field-theory model with two massless fermions,
coupled to an Abelian vector field without flavour mixing, and to another
Abelian vector field with flavour mixing. Both Abelian vectors have a
Lorentz-violating kinetic term, introducing a Lorentz-violation mass scale $M$,
from which fermions and the flavour-mixing vector get their dynamical masses,
whereas the vector coupled without flavour mixing remains massless. When the
two coupling constants have similar values in order of magnitude, a mass
hierarchy pattern emerges, in which one fermion is very light compared to the
other, whilst the vector mass is larger than the mass of the heavy fermion. The
work presented here may be considered as a Lorentz-symmetry-Violating
alternative to the Higgs mechanism, in the sense that no scalar particle
(fundamental or composite) is necessary for the generation of the vector-meson
mass. However, the model is not realistic given that, as a result of Lorentz
Violation, the maximal (light-cone) speed seen by the fermions is smaller than
that of the massless gauge boson (which equals the speed of light in vacuo) by
an amount which is unacceptably large to be compatible with the current tests
of Lorentz Invariance, unless the gauge couplings assume unnaturally small
values. Possible ways out of this phenomenological drawback are briefly
discussed, postponing a detailed construction of more realistic models for
future work.",1108.3983v1
2011-10-09,Lorentz Violation of the Photon Sector in Field Theory Models,"We compare the Lorentz violation terms of the pure photon sector between two
field theory models, namely the minimal standard model extension (SME) and the
standard model supplement (SMS). From the requirement of the identity of the
intersection for the two models, we find that the free photon sector of the SMS
can be a subset of the photon sector of the minimal SME. We not only obtain
some relations between the SME parameters, but also get some constraints on the
SMS parameters from the SME parameters. The CPT-odd coefficients
$(k_{AF})^{\alpha}$ of the SME are predicted to be zero. There are 15 degrees
of freedom in the Lorentz violation matrix $\Delta^{\alpha\beta}$ of free
photons of the SMS related with the same number of degrees of freedom in the
tensor coefficients $(k_F)^{\alpha\beta\mu\nu}$, which are independent from
each other in the minimal SME, but are inter-related in the intersection of the
SMS and the minimal SME. With the related degrees of freedom, we obtain the
conservative constraints ($2\sigma$) on the elements of the photon Lorentz
violation matrix. The detailed structure of the photon Lorentz violation matrix
suggests some applications to the Lorentz violation experiments for photons.",1110.1850v3
2012-06-19,Averaged dynamics of ultra-relativisitc charged particles beams,"In this thesis, we consider the suitability of using the charged cold fluid
model in the description of ultra-relativistic beams. The method that we have
used is the following. Firstly, the necessary notions of kinetic theory and
differential geometry of second order differential equations are explained.
Then an averaging procedure is applied to a connection associated with the
Lorentz force equation. The result of this averaging is an affine connection on
the space-time manifold. The corresponding geodesic equation defines the
averaged Lorentz force equation. We prove that for ultra-relativistic beams
described by narrow distribution functions, the solutions of both equations are
similar. This fact justifies the replacement of the Lorentz force equation by
the simpler {\it averaged Lorentz force equation}. After this, for each of
these models we associate the corresponding kinetic model, which are based on
the Vlasov equation and {\it averaged Vlasov equation} respectively. The
averaged Vlasov equation is simpler than the original Vlasov equation. This
fact allows us to prove that the differential operation defining the averaged
charged cold fluid equation is controlled by the {\it diameter of the
distribution function}, by powers of the {\it energy of the beam} and by the
time of evolution $t$. We show that the Vlasov equation and the averaged Vlasov
equation have similar solutions, when the initial conditions are the same.
Finally, as an application of the {\it averaged Lorentz force equation} we
re-derive the beam dynamics formalism used in accelerator physics from the
Jacobi equation of the averaged Lorentz force equation.",1206.4184v1
2013-11-15,One-loop nonbirefringent effects on the electromagnetic vertex in the Standard Model Extension,"Lorentz violation emerged from a fundamental description of nature may
impact, at low energies, the Maxwell sector, so that contributions from such
new physics to the electromagnetic vertex would be induced. Particularly,
nonbirefringent $CPT$-even effects from the electromagnetic sector modified by
the Lorentz- and $CPT$-violating Standard Model Extension alter the structure
of the free photon propagator. We calculate Lorentz-violating contributions to
the electromagnetic vertex, at the one-loop level, by using a modified photon
propagator carrying this sort of effects. We take the photon off shell, and
find an expression that involves both isotropic and anisotropic effects of
nonbirefringent violation of Lorentz invariance. Our analysis of the one-loop
vertex function includes gauge invariance, transformation properties under $C$,
$P$, and $T$, and tree-level contributions from Lorentz-violating
nonrenormalizable interactions. These elements add to previous studies of the
one-loop contributions to the electromagnetic vertex in the context of Lorentz
violation in the photon sector. Finally, we restrict our analysis to the
isotropic case and derive a finite contribution from isotropic Lorentz
violation to the anomalous magnetic moment of fermions that coincides with the
result already reported in the literature.",1311.3744v2
2015-06-18,Acousto-electrical speckle pattern in Lorentz force electrical impedance tomography,"Ultrasound speckle is a granular texture pattern appearing in ultrasound
imaging. It can be used to distinguish tissues and identify pathologies.
Lorentz force electrical impedance tomography is an ultrasound-based medical
imaging technique of the tissue electrical conductivity. It is based on the
application of an ultrasound wave in a medium placed in a magnetic field and on
the measurement of the induced electric current due to Lorentz force. Similarly
to ultrasound imaging, we hypothesized that a speckle could be observed with
Lorentz force electrical impedance tomography imaging. In this study, we first
assessed the theoretical similarity between the measured signals in Lorentz
force electrical impedance tomography and in ultrasound imaging modalities. We
then compared experimentally the signal measured in both methods using an
acoustic and electrical impedance interface. Finally, a bovine muscle sample
was imaged using the two methods. Similar speckle patterns were observed. This
indicates the existence of an ""acousto-electrical speckle"" in the Lorentz force
electrical impedance tomography with spatial characteristics driven by the
acoustic parameters but due to electrical impedance inhomogeneities instead of
acoustic ones as is the case of ultrasound imaging.",1506.05589v1
2015-06-21,One and two spin$-1/2$ particles systems under Lorentz transformations,"Lorentz transformation (LT) is used to connect two inertia frames, including
the lab and moving frames, and the effect of LT on the states of one spin-1/2
particle system is studied. Moreover, we address the predictions made by
Czachor's and the Pauli spin operators about the spin behavior and compare our
results with the behavior of system's state under Lorentz transformation. This
investigation shows that the predictions made by considering the Pauli spin
operator about the spin of system are in better agreement with the system's
state in comparison with that of made by considering Czachor's spin operator.
In continue, we focus on two-particle pure entangled systems including two
spin$-1/2$ particles which moves away from each other. Once again, the behavior
of this system's states under Lorentz transformation are investigated. We also
point to the behavior of Bell's inequality, as a witness for non-locality,
under Lorentz transformation. Our study shows that the Bell operator made by
the Pauli operator has better consistency with the behavior of spin state of
system under Lorentz transformation compared with the Bell operator made by
Czachor's operator. Our approach can be used to study the relation between the
various spin operators and the effect of LT on system, which provides the
basement to predict the outcome of a Stern-Gerlach type experiment in the
relativistic situations.",1506.07106v5
2015-08-02,"Eikonal approximation, Finsler structures, and implications for Lorentz-violating photons in weak gravitational fields","The current article shall contribute to understanding the classical analogue
of the minimal photon sector in the Lorentz-violating Standard-Model Extension
(SME). It is supposed to complement all studies performed on classical
point-particle equivalents of SME fermions. The classical analogue of a photon
is not a massive particle being described by a usual equation of motion, but a
geometric ray underlying the eikonal equation. The first part of the paper will
set up the necessary tools to understand this correspondence for interesting
cases of the minimal SME photon sector. In conventional optics the eikonal
equation follows from an action principle, which is demonstrated to work in
most (but not all) Lorentz-violating cases as well. The integrands of the
action functional correspond to Finsler structures, which establishes the
connection to Finsler geometry. The second part of the article treats
Lorentz-violating light rays in a weak gravitational background by implementing
the principle of minimal coupling. Thereby it is shown how Lorentz violation in
the photon sector can be constrained by measurements of light bending at
massive bodies such as the Sun. The phenomenological studies are based on the
currently running ESA mission GAIA and the planned NASA/ESA mission LATOR. The
final part of the paper discusses certain aspects of explicit Lorentz violation
in gravity based on the setting of Finsler geometry.",1508.00216v1
2016-07-29,"The role of singular spinor fields in a torsional gravity, Lorentz-violating, framework","In this work, we consider a generalization of quantum electrodynamics
including Lorentz violation and torsional-gravity, in the context of general
spinor fields as classified in the Lounesto scheme. Singular spinor fields will
be shown to be less sensitive to the Lorentz violation, as far as couplings
between the spinor bilinear covariants and torsion are regarded. In addition,
we prove that flagpole spinor fields do not admit minimal coupling to the
torsion. In general, mass dimension four couplings are deeply affected when
singular flagpole spinors are considered, instead of the usual Dirac spinors.
We also construct a mapping between spinors in the covariant framework and
spinors in Lorentz symmetry breaking scenarios, showing how one may
transliterate spinors of different classes between the two cases. Specific
examples concerning the mapping of Dirac spinor fields in Lorentz violating
scenarios into flagpole and flag-dipole spinors with full Lorentz invariance
(including the cases of Weyl and Majorana spinors) are worked out.",1607.08670v3
2017-02-13,On the Linear Stability of Magnetized Jets Without Current Sheets - Relativistic Case,"In our prior papers, we considered the non-relativistic linear stability
analysis of magnetized jets that do not have current sheet at the boundary. In
this paper, we extend our analysis to relativistic jets. In order to find the
unstable modes of current sheet-free, magnetized relativistic jets, we
linearize full relativistic magnetohydrodynamics equations and solve them
numerically. We find the dispersion relation of the pinch and kink mode
instabilities. By comparing the dispersion relations of mildly relativistic jet
(Lorentz factor 2) with moderately relativistic jet (Lorentz factor 10), we
find that the jet with higher Lorentz factor is significantly more stable in
both pinch and kink modes. We show that inclusion of the current sheet-free
magnetic field in the jet further enhances the stability. Both pinch and kink
mode instabilities become progressively more stable with increasing
magnetization. We also show a scaling relation between the maximum temporal
growth rate of the unstable mode and the Lorentz factor of the jet. The maximum
temporal growth rates of the unstable modes are inversely proportion to the
Lorentz factors for most of the modes that we study. However, for the
fundamental pinch mode it is inversely proportional to the square of the
Lorentz factor. This very beneficial scaling relation holds regardless of the
presence of a magnetic field.",1702.03882v1
2018-02-05,Abstract Lorentz spaces and Köthe duality,"Given a fully symmetric Banach function space $E$ and a decreasing positive
weight $w$ on $I = (0, a)$, $0 < a \le \infty $, the generalized Lorentz space
${\Lambda}_{E,w}$ is defined as the symmetrization of the canonical copy $E_w$
of $E$ on the measure space associated with the weight. If $E$ is an Orlicz
space then ${\Lambda}_{E,w}$ is an Orlicz-Lorentz space. An investigation of
the K\""othe duality of these classes is developed that is parallel to
preceding works on Orlicz-Lorentz spaces. First a class of functions $M_{E,w}$,
which does not need to be even a linear space, is similarly defined as the
symmetrization of the space $w.E_w$. Let also $Q_{E,w}$ be the smallest fully
symmetric Banach function space containing $M_{E,w}$. Then the K\""othe dual of
the class $M_{E,w}$ is identified as the Lorentz space ${\Lambda}_{E',w}$,
while the K\""othe dual of ${\Lambda}_{E,w}$ is $Q_{E',w}$. The space $Q_{E,w}$
is also characterized in terms of Halperin's level functions. These results are
applied to concrete Banach function spaces. In particular the K\""othe duality
of Orlicz-Lorentz spaces is revisited at the light of the new results.",1802.01728v2
2010-05-20,Lorentz shift measurements in heavily irradiated silicon detectors in high magnetic fields,"An external magnetic field exerts a Lorentz force on drifting electric
charges inside a silicon strip sensor and thus shifts the cluster position of
the collected charge. The shift can be related to the Lorentz angle which is
typically a few degrees for holes and a few tens of degrees for electrons in a
4 T magnetic field. The Lorentz angle depends upon magnetic field, electric
field inside the sensor and temperature. In this study the sensitivity to
radiation for fluences up to 10^16 n/cm^2 has been studied. The Lorentz shift
has been measured by inducing ionization with 670 nm red or 1070 nm infrared
laser beams injected into the back side of the irradiated silicon sensor
operated in magnetic fields up to 8 T. For holes the shift as a function of
radiation is increasing, while for electrons it is decreasing and even changes
sign. The fact that for irradiated sensors the Lorentz shift for electrons is
smaller than for holes, in contrast to the observations in non-irradiated
sensors, can be qualitatively explained by the structure of the electric field
in irradiated sensors.",1005.3629v1
2016-11-15,Evaluating the bulk Lorentz factors of outflow material: lessons learned from the extremely-energetic outburst GRB 160625B,"GRB 160625B is an extremely-bright outburst with well-monitored afterglow
emission. The geometry-corrected energy is high up to $\sim 5.2\times10^{52}$
erg or even $\sim 8\times 10^{52}$ erg, rendering it the most energetic GRB
prompt emission recorded so far. We analyzed the time-resolved spectra of the
prompt emission and found that in some intervals there were likely
thermal-radiation components and the high energy emission were characterized by
significant cutoff. The bulk Lorentz factors of the outflow material are
estimated accordingly. We found out that the Lorentz factors derived in the
thermal-radiation model are consistent with the luminosity-Lorentz factor
correlation found in other bursts as well as in GRB 090902B for the
time-resolved thermal-radiation components. While the spectral cutoff model
yields much lower Lorentz factors that are in tension with the constraints set
by the electron pair Compoton scattering process. We then suggest that these
spectral cutoffs are more likely related to the particle acceleration process
and that one should be careful in estimating the Lorentz factors if the
spectrum cuts at a rather low energy (e.g., $\sim$ tens MeV). The nature of the
central engine has also been discussed and a stellar-mass black hole is likely
favored.",1611.04879v2
2017-04-20,Constraining Anisotropic Lorentz Violation via the Spectral-Lag Transition of GRB 160625B,"Violations of Lorentz invariance can lead to an energy-dependent vacuum
dispersion of light, which results in arrival-time differences of photons
arising with different energies from a given transient source. In this work,
direction-dependent dispersion constraints are obtained on nonbirefringent
Lorentz-violating effects, using the observed spectral lags of the gamma-ray
burst GRB 160625B. This burst has unusually large high-energy photon
statistics, so we can obtain constraints from the true spectral time lags of
bunches of high-energy photons rather than from the rough time lag of a single
highest-energy photon. Also, GRB 160625B is the only burst to date having a
well-defined transition from positive lags to negative lags, which provides a
unique opportunity to distinguish Lorentz-violating effects from any
source-intrinsic time lag in the emission of photons of different energy bands.
Our results place comparatively robust two-sided constraints on a variety of
isotropic and anisotropic coefficients for Lorentz violation, including first
bounds on Lorentz-violating effects from operators of mass dimension ten in the
photon sector.",1704.05984v2
2018-05-25,Revisiting Lorentz violation in Horava gravity,"In the context of Horava gravity, the most promising known scenarios to
recover Lorentz invariance at low energy are the possibilities that (1) the
renormalization group flow of the system leads to emergent infrared Lorentz
invariance, and (2) that supersymmetry protects infrared Lorentz invariance. A
third scenario proposes that a classically Lorentz invariant matter sector with
controlled quantum corrections may simply co-exist with Horava gravity under
certain conditions. However, for non-projectable Horava gravity in 3+1
dimensions it is known that, in the absence of additional structures, this
mechanism is spoiled by unexpected power-law divergences. We confirm this same
result in the projectable version of the theory by employing the recently found
gauge-fixing term that renders the shift and graviton propagators regular. We
show that the problem persists for all dimensions $D\geq 3$, and that the
degree of fine tuning in squared sound speeds between a U(1) gauge field and a
scalar field increases with $D$. In particular, this difference in the zero
external momentum limit is proportional to $\Lambda^{D-1}$ for $D\geq 3$, where
$\Lambda$ is the ultraviolet momentum cutoff for loop integrals, while the
power-law divergences are absent for $D=1$ and $D=2$. These results suggest
that not only the gravity sector but also the matter sector should exhibit a
transition to Lifshitz scaling above some scale, and that there should not be a
large separation between the transition scales in the gravity and matter
sectors. We close with a discussion of other more promising scenarios,
including emergent Lorentz invariance from supersymmetry/strong dynamics, and
pointing out challenges where they exist.",1805.10299v1
2011-11-30,Spontaneously broken Lorentz symmetry for Hamiltonian gravity,"In Ashtekar's Hamiltonian formulation of general relativity, and in loop
quantum gravity, Lorentz covariance is a subtle issue that has been strongly
debated. Maintaining manifest Lorentz covariance seems to require introducing
either complex-valued fields, presenting a significant obstacle to
quantization, or additional (usually second class) constraints whose solution
renders the resulting phase space variables harder to interpret in a spacetime
picture. After reviewing the sources of difficulty, we present a Lorentz
covariant, real formulation in which second class constraints never arise.
Rather than a foliation of spacetime, we use a gauge field y, interpreted as a
field of observers, to break the SO(3,1) symmetry down to a subgroup SO(3)_y.
This symmetry breaking plays a role analogous to that in MacDowell-Mansouri
gravity, which is based on Cartan geometry, leading us to a picture of gravity
as 'Cartan geometrodynamics.' We study both Lorentz gauge transformations and
transformations of the observer field to show that the apparent breaking of
SO(3,1) to SO(3) is not in conflict with Lorentz covariance.",1111.7195v4
2018-01-02,Global Dirac bispinor entanglement under Lorentz boosts,"The effects of Lorentz boosts on the quantum entanglement encoded by a pair
of massive spin one-half particles are described according to the Lorentz
covariant structure described by Dirac bispinors. The quantum system considered
incorporates four degrees of freedom -- two of them related to the bispinor
intrinsic parity and other two related to the bispinor spin projection, i.e.
the Dirac particle helicity. Because of the natural multipartite structure
involved, the Meyer-Wallach global measure of entanglement is preliminarily
used for computing global quantum correlations, while the entanglement
separately encoded by spin degrees of freedom is measured through the
negativity of the reduced two-particle spin-spin state. A general framework to
compute the changes on quantum entanglement induced by a boost is developed,
and then specialized to describe three particular anti-symmetric two-particle
states. According to the obtained results, two-particle spin-spin entanglement
cannot be created by the action of a Lorentz boost in a spin-spin separable
anti-symmetric state. On the other hand, the maximal spin-spin entanglement
encoded by anti-symmetric superpositions is degraded by Lorentz boosts driven
by high-speed frame transformations. Finally, the effects of boosts on chiral
states are shown to exhibit interesting invariance properties, which can only
be obtained through such a Lorentz covariant formulation of the problem.",1801.00758v2
2019-06-14,The concept of weak measurements and the super-efficiency of quantum tomography,"The quantum measurement procedure based on the Lorentz transformation
formalism and weak perturbation of the system is considered. In the simple case
of a single-qubit it turns out that one can perform 4-dimension pseudo-rotation
along with ordinary 3-dimension rotations on the Bloch sphere. These
pseudo-rotations are similar to the Lorentz transformation in special
relativity theory. The extension of the Lorentz transformation for many-qubit
systems is also considered. The quantum measurement protocols based on the
Lorentz transformation are proposed. It has been shown that these protocols
cease to form the decomposition of unity and could be superefficient providing
the fidelity higher than any POVM-measurement protocol. However, one can
perform the complement of the Lorentz protocol to POVM-protocol by an
additional measurement operator. If the initial mixed state is close to the
pure one this operator corresponds to weak perturbation of the state while the
original Lorentz protocol sets the strong perturbations. As the result, the
feedback provides an effective control of a quantum system introducing weak
perturbations to the quantum state. The results of this research are essential
for the development of methods for the control of quantum information
technologies.",1906.06377v1
2019-09-16,Global gradient estimates for very singular quasilinear elliptic equations with measure data,"This paper continues the development of regularity results for quasilinear
measure data problems \begin{align*} \begin{cases} -\mathrm{div}(A(x,\nabla u))
&= \mu \quad \text{in} \ \ \Omega, \\ \quad \quad \qquad u &=0 \quad \text{on}
\ \ \partial \Omega, \end{cases} \end{align*} in Lorentz and Lorentz-Morrey
spaces, where $\Omega \subset \mathbb{R}^n$ ($n \ge 2$), $\mu$ is a finite
Radon measure on $\Omega$, and $A$ is a monotone Carath\'eodory vector valued
operator acting between $W^{1,p}_0(\Omega)$ and its dual $W^{-1,p'}(\Omega)$.
It emphasizes that this paper studies the `very singular' case $1<p \le
\frac{3n-2}{2n-1}$ and the problem is considered under the weak assumption,
where the $p$-capacity uniform thickness condition is imposed on the complement
of domain $\Omega$. There are two main results obtained in our study pertaining
to the global gradient estimates of solutions in Lorentz and Lorentz-Morrey
spaces involving the use of maximal and fractional maximal operators. The idea
for writing this working paper comes directly from the recent results by others
in the same research topic, where global estimates for gradient of solutions
for the `very singular' case still remains a challenge, specifically related to
Lorentz and Lorentz-Morrey spaces.",1909.06991v3
2020-02-04,Analysis on Complete Set of Fock States with Explicit Wavefunctions for the Covariant Harmonic Oscillator Problem,"The earlier treatments of Lorentz covariant harmonic oscillator have brought
to light various difficulties, such as reconciling Lorentz symmetry with the
full Fock space, and divergence issues with their functional representations.
We present here a full solution avoiding those problems. The complete set of
Fock states is obtained, together with the corresponding explicit wavefunction
and their inner product integrals free from any divergence problem and the
Lorentz symmetry fully maintained without additional constraints imposed. By a
simple choice of the pseudo-unitary representation of the underlying symmetry
group, motivated from the perspective of the Minkowski spacetime as a
representation for the Lorentz group, we obtain the natural non-unitary Fock
space picture commonly considered though not formulated and presented in the
careful details given here. From a direct derivation of the appropriate basis
state wavefunctions of the finite-dimensional irreducible representations of
the Lorentz symmetry, the relation between the latter and the Fock state
wavefunctions is also explicitly shown. Moreover, the full picture including
the states with non-positive norm may give consistent physics picture as a
version of Lorentz covariant quantum mechanics. Probability interpretation for
the usual von Neumann measurements is not a problem as all wavefunctions
restricted to a definite value for the `time' variable are just like those of
the usual time independent quantum mechanics. A further understanding from a
perspective of the dynamics from the symplectic geometry of the phase space is
shortly discussed.",2002.08467v2
2020-12-18,"Direct derivation of Lienard Wiechert potentials, Maxwell's equations and Lorentz force from Coulomb's law","In 19th century Maxwell derived Maxwell equations from the knowledge of three
experimental physical laws: the Coulomb's law, the Ampere's force law and
Faraday's law of induction. However, theoretical basis for Ampere's force law
and Faraday's law remains unknown to this day. Furthermore, the Lorentz force
is considered as experimental phenomena, the theoretical foundation of this
force is still unknown.
  To answer these fundamental theoretical questions, we derive Lienard Wiechert
potentials, Maxwell's equations and Lorentz force from two simple postulates:
(a) when all charges are at rest the Coulomb's force acts between the charges,
and (b) that disturbances caused by charge in motion propagate away from the
source with finite velocity. The special relativity was not used in our
derivations nor the Lorentz transformation. In effect, it was shown all the
electrodynamic laws, including the Lorentz force, can be derived from Coulomb's
law and time retardation.
  This was accomplished by analysis of hypothetical experiment where test
charge is at rest and where previously moving source charge stops at some time
in the past. Then the generalized Helmholtz decomposition theorem, also derived
in this paper, was applied to reformulate Coulomb's force acting at present
time as the function of positions of source charge at previous time when the
source charge was moving. From this reformulation of Coulomb's law the Lienard
Wiechert potentials and Maxwell's equations were derived.
  In the second part of this paper, the energy conservation principle valid for
moving charges is derived from the knowledge of electrostatic energy
conservation principle valid for stationary charges. This again was
accomplished by using generalized Helmholtz decomposition theorem. From this
dynamic energy conservation principle the Lorentz force is derived.",2012.11370v1
2012-05-01,Trouble with the Lorentz law of force: Incompatibility with special relativity and momentum conservation,"The Lorentz law of force is the fifth pillar of classical electrodynamics,
the other four being Maxwell's macroscopic equations. The Lorentz law is the
universal expression of the force exerted by electromagnetic fields on a volume
containing a distribution of electrical charges and currents. If electric and
magnetic dipoles also happen to be present in a material medium, they are
traditionally treated by expressing the corresponding polarization and
magnetization distributions in terms of bound-charge and bound-current
densities, which are subsequently added to free-charge and free-current
densities, respectively. In this way, Maxwell's macroscopic equations are
reduced to his microscopic equations, and the Lorentz law is expected to
provide a precise expression of the electromagnetic force density on material
bodies at all points in space and time. This paper presents incontrovertible
theoretical evidence of the incompatibility of the Lorentz law with the
fundamental tenets of special relativity. We argue that the Lorentz law must be
abandoned in favor of a more general expression of the electromagnetic force
density, such as the one discovered by A. Einstein and J. Laub in 1908. Not
only is the Einstein-Laub formula consistent with special relativity, it also
solves the long-standing problem of ""hidden momentum"" in classical
electrodynamics.",1205.0096v1
2018-06-04,A complete Lorentz-to-Galileo dictionary for direct Dark Matter detection,"We determine the most general non-relativistic theory of DM-nucleon
scattering complying with the sole requirement of Lorentz invariance, for
spin-0 and spin-1/2 DM. To do so, we first classify a comprehensive list of
amplitude terms encompassing the most general Lorentz-covariant 2-to-2
DM-nucleon scattering amplitude. We then match each term to a
Galilean-invariant operator at leading-order in the non-relativistic expansion,
for both elastic and inelastic (endothermic and exothermic) scattering. Our
complete Lorentz-to-Galileo mapping can be used to promptly determine the
non-relativistic DM-nucleon interaction and the associated nuclear form factor
for any given Lorentz-invariant DM model. It applies to both renormalizable and
non-renormalizable theories (such as effective field theories at all orders),
at any order of a perturbative expansion. We use our results to prove that, at
leading order, Lorentz invariance does not impose restrictions on the set of 16
Galilean-invariant operators commonly used to parametrize the non-relativistic
DM-nucleon interaction. We also predict the lowest effective-operator dimension
at which the non-relativistic operators appear in the effective field theory of
a singlet DM particle.",1806.01291v2
2019-02-18,Gravitational Searches for Lorentz Violation with Ultracold Neutrons,"We investigate the consequences of Lorentz violation (as expressed within the
gravity sector of the Standard-Model Extension) for gravitational quantum
states of ultracold neutrons (UCNs). Since our main aim is to compare our
theoretical results with the recent high-sensitivity GRANIT experiment, we
frame this work according to the laboratory conditions under which it was
carried out. This offers the possibility of testing Lorentz invariance by
experiments using UCNs. Thus we consider the nonrelativistic Hamiltonian
describing the quantum mechanics of an unpolarized neutron's beam in presence
of a weak-gravity field, and the latter is described by a post-Newtonian
expansion of the metric up to order $O (2)$ and linear in the Lorentz-violating
coefficients $\bar{s} ^{\mu \nu}$. Using a semi-classical wave packet, which is
appropriate to describe an intense beam of UCNs, we derive the effective
Hamiltonian describing the neutron's motion along the axis of free fall and
then we compute the Lorentz-violating shifts on the energy levels. The
comparison of our results with those obtained in the GRANIT experiment leads to
an upper bound for a particular combination of the Lorentz-violating
coefficients.",1902.06399v2
2019-03-12,Using synchrotron emission modelling of relativistic hydrodynamic jet simulations to study the FR I/FR II dichotomy of Active Galactic nuclei radio jets,"In this paper three dimensional relativistic hydrodynamic simulations of AGN
jets are presented to investigate the FR I/FR II dichotomy. Three simulations
are presented which illustrates the difference in morphology for high/low
Lorentz factor injection as well as a stratified background medium. Lorentz
factors of 10 and 1.0014 were used for the high and low Lorentz factor cases
respectively. The hydrodynamic simulations show a division in the morphology of
jets based on their initial injection luminosity. An additional simulation was
set up to investigate the evolution of the low Lorentz factor jet if the mass
injection was lowered after a certain time. A synchrotron emission model was
applied to these simulations to reproduce intensity maps at radio frequencies
(1.5GHz) which were compared to the observed emission structures of FR I/FR II
radio galaxies. The effect of Doppler boosting on the intensity maps was also
investigated for different polar angles. The intensity maps of both the high
and low Lorentz factor cases reproduced emission structures that resemble those
of FR II type radio galaxies with a dominant cocoon region containing time
dependent hot spots and filaments. An FR I like structure was, however,
produced for the low Lorentz factor case if the mass injection rate was lowered
after a set time period.",1903.04859v1
2019-04-10,Flare reconnection-driven magnetic field and Lorentz force variations at the Sun's surface,"During eruptive flares, vector magnetograms show increasing horizontal
magnetic field and downward Lorentz force in the Sun's photosphere around the
polarity-inversion line. Such behavior has often been associated with the
implosion conjecture and interpreted as the result of either momentum
conservation while the eruption moves upward, or of the contraction of flare
loops. We characterize the physical origin of these observed behaviors by
analyzing a generic 3D MHD simulation of an eruptive flare. Even though the
simulation was undesigned to recover the magnetic field and Lorentz force
properties, it is fully consistent with them, and it provides key additional
informations to understand them. The area where the magnetic field increases
gradually develops between current ribbons, which spread away from each other
and are connected to the coronal region. This area is merely the footprint of
the coronal post-flare loops, whose contraction increases their shear field
component and the magnetic energy density in line with the ideal induction
equation. For simulated data, we computed the Lorentz force density map by
applying the method used in observations. We obtained increase of the downward
component of the Lorentz force density around the PIL -consistent with
observations. However, this significantly differs from the Lorentz force
density maps obtained directly from the 3D magnetic field and current. These
results altogether question previous interpretations based on the implosion
conjecture and momentum conservation with the CME, and rather imply that the
observed increases in photospheric horizontal magnetic fields result from the
reconnection-driven contraction of sheared flare-loops.",1904.05447v2
2019-04-23,Neutrino Splitting for Lorentz-Violating Neutrinos: Detailed Analysis,"Lorentz-violating neutrino parameters have been severely constrained on the
basis of astrophysical considerations. In the high-energy limit, one generally
assumes a superluminal dispersion relation of an incoming neutrino of the form
E ~ |p|v, where E is the energy, p is the momentum and $v = sqrt(1 + delta) >
1. Lepton-pair creation due to a Cerenkov-radiation-like process (nu -> nu +
e^- + e^+) becomes possible above a certain energy threshold, and bounds on the
Lorentz-violating parameter delta can be derived. Here, we investigate a
related process, nu_i -> nu_i + nu_f + bar_nu_f, where nu_i is an incoming
neutrino mass eigenstate, while nu_f is the final neutrino mass eigenstate,
with a superluminal velocity that is slightly slower than that of the initial
state. This process is kinematically allowed if the Lorentz-violating
parameters at high energy differ for the different neutrino mass eigenstates.
Neutrino splitting is not subject to any significant energy threshold condition
and could yield quite a substantial contribution to decay and energy loss
processes at high energy, even if the differential Lorentz violation among
neutrino flavors is severely constrained by other experiments. We also discuss
the SU(2)-gauge invariance of the superluminal models and briefly discuss the
use of a generalized vierbein formalism in the formulation of the
Lorentz-violating Dirac equation.",1904.10505v2
2020-06-20,Testing the Weak Equivalence Principle and Lorentz Invariance with Multiwavelength Polarization Observations of GRB Optical Afterglows,"Violations of both the weak equivalence principle (WEP) and Lorentz
invariance can produce vacuum birefringence, which leads to an energy-dependent
rotation of the polarization vector of linearly polarized emission from a given
astrophysical source. However, the search for the birefringent effect has been
hindered by our ignorance concerning the intrinsic polarization angle in
different energy bands. Considering the contributions to the observed linear
polarization angle from both the intrinsic polarization angle and the rotation
angles induced by violations of the WEP and Lorentz invariance, and assuming
the intrinsic polarization angle is an unknown constant, we simultaneously
obtain robust bounds on possible deviations from the WEP and Lorentz
invariance, by directly fitting the multiwavelength polarimetric data of the
optical afterglows of gamma-ray burst (GRB) 020813 and GRB 021004. Here we show
that at the $3\sigma$ confidence level, the difference of the parameterized
post-Newtonian parameter $\gamma$ values characterizing the departure from the
WEP is constrained to be
$\Delta\gamma=\left(-4.5^{+10.0}_{-16.0}\right)\times10^{-24}$ and the
birefringent parameter $\eta$ quantifying the broken degree of Lorentz
invariance is limited to be
$\eta=\left(6.5^{+15.0}_{-14.0}\right)\times10^{-7}$. These are the first
simultaneous verifications of the WEP and Lorentz invariance in the photon
sector. More stringent limits can be expected as the analysis presented here is
applied to future multiwavelength polarization observations in the prompt
gamma-ray emission of GRB",2006.11528v1
2020-11-12,Constraining velocity-dependent Lorentz/CPT-violations using Lunar Laser Ranging,"The possibility for Lorentz/CPT-breaking, which is motivated by unification
theories, can be systematically tested within the standard-model extension
framework. In the pure gravity sector, the mass dimension 5 operators produce
new Lorentz and CPT-breaking terms in the 2-body equations of motion that
depend on the relative velocity of the bodies. In this Letter, we report new
constraints on 15 independent SME coefficients for Lorentz/CPT-violations with
mass dimension 5 using lunar laser ranging. We perform a global analysis of
lunar ranging data within the SME framework using more than 26,000 normal
points between 1969 and 2018. We also perform a jackknife analysis in order to
provide realistic estimates of the systematic uncertainties. No deviation from
Lorentz/CPT symmetries is reported. In addition, when fitting simultaneously
for the 15 canonical SME coefficients for Lorentz/CPT-violations, we improve up
to three orders of magnitude previous post-fit constraints from radio pulsars.",2011.06641v1
2021-03-31,Study of Einstein-bumblebee gravity with Kerr-Sen-like solution in the presence of a dispersive medium,"A Kerr-Sen-like black hole solution appears in the Einstein-bumblebee theory
of gravity. The solution contains contains a Lorentz violating parameter in an
explicit manner. We study the null geodesics in the background of this
Kerr-Sen-like black hole surrounded by a dispersive medium like plasma. We
investigate the effect of the charge of the black hole, the Lorentz violation
parameter, and the plasma parameter on the photon orbits with the evaluation of
the effective potential in the presence of both the Lorentz violation parameter
and the plasma parameter. We also study the influence of the Lorentz violation
parameter and plasma parameter on the emission of energy from the black hole
due to thermal radiation. Besides, we compute the angle of deflection of
massless particles with weak-field approximation in this generalized situation
and examine how it varies with the Lorentz violation parameter in presence of
plasma. Constraining the parameters of this Lorentz violating Kerr-Sen-like
black hole is also attempted here with the result obtained from the
observations of the Event Horizon Telescope (EHT) collaboration.",2103.17021v2
2021-06-25,Wave packets in QFT: leading order width corrections to decay rates and clock behaviour under Lorentz boosts,"Decay rates in quantum field theory (QFT) are typically calculated assuming
the particles are represented by momentum eigenstates (i.e. plane waves).
However, strictly speaking, localized free particles should be represented by
wave packets. This yields width corrections to the decay rate and to the clock
behaviour under Lorentz boosts. We calculate the decay rate of a particle of
mass $M$ modeled as a Gaussian wavepacket of width $a$ and centered at zero
momentum. We find the decay rate to be $\Gamma_0 \big[1- \frac{3 a^2}{4 M^2}
+\mathcal{O}\big(\tfrac{a^4}{M^4}\big)\big]$ where $\Gamma_0$ is the decay rate
of the particle at rest treated as a plane wave. The leading correction is then
of order $\tfrac{a^2}{M^2}$. We then perform a Lorentz boost of velocity $v$ on
the above Gaussian and find that its decay rate does not decrease
\textit{exactly} by the Lorentz factor $\sqrt{1-v^2}$. There is a correction of
order $\tfrac{a^2v^2}{M^2}$. Therefore, the decaying wave packet does not act
exactly like a typical clock under Lorentz boosts and we refer to it is a ""WP
clock"" (wave packet clock). A WP clock does not move with a single velocity
relative to an observer but has a spread in velocities (more specifically, a
spread in momenta). Nonetheless, it is best viewed as a single clock as the
wave packet represents a one-particle state in QFT. WP clocks do not violate
Lorentz symmetry and are not based on new physics: they are a consequence of
the combined requirements of special relativity, quantum mechanics and
\textit{localized} free particles.",2106.13768v1
2021-11-03,Tests of Lorentz Invariance,"Lorentz invariance is a fundamental symmetry of both Einstein's theory of
general relativity and quantum field theory. However, deviations from Lorentz
invariance at energies approaching the Planck scale are predicted in many
quantum gravity theories seeking to unify the force of gravity with the other
three fundamental forces of matter. Even though any violations of Lorentz
invariance are expected to be very small at observable energies, they can
increase with energy and accumulate to detectable levels over large distances.
Astrophysical observations involving high-energy emissions and long baselines
can therefore offer exceptionally sensitive tests of Lorentz invariance. With
the extreme features of astrophysical phenomena, it is possible to effectively
search for signatures of Lorentz invariance violations (LIV) in the photon
sector, such as vacuum dispersion, vacuum birefringence, photon decay, and
photon splitting. All of these potential signatures have been studied carefully
using different methods over the past few decades. This chapter attempts to
review the status of our current knowledge and understanding of LIV, with
particular emphasis on a summary of various astrophysical tests that have been
used to set lower limits on the LIV energy scales.",2111.02029v1
2021-11-04,Lorentz violation and noncommutative effect on superradiance scattering off Kerr-like black hole and on the shadow of it,"We consider a Lorentz violating non-commutating Kerr-like spacetime and
studied the superradiance effect and the shadow cast by the back hole. We
extensively study the different aspects of the black hole associated with a
generalized Kerr-like spacetime metric endowed with the corrections licked with
Lorentz violation and non-commutativity effect jointly. We investigate the
superradiance effect, deviation of shape, and size of the ergosphere, energy
emission rate, and black hole shadow in this generalized situation and study
their variation taking different admissible values of Lorentz violating
parameter $l$ and non-commutative parameter $b$. The admissible range has been
determined from the observation of the Event Horizon Telescope (EHT)
collaboration concerning $M87_8$ astronomical black hole. We observe that the
superradiance phenomena has a crucially depends on the parameter $l$ and $b$
apart from its dependence on $a$ which is linked to the spin of the black hole.
We also observe that with the increase in Lorentz violating parameter $l$, the
size of the black hole shadow increases, and with the increase in the
non-commutative parameter $b$, the size of the black hole decreases. We have
made an attempt to constrain parameters $b$ of a non-commutative Kerr-like
black hole using the observation available from the EHT collaboration, in the
same way, we put constrain on the Lorentz violating parameter $l$. This study
shows that black holes associated with non-commutative Kerr-like spacetime may
be a suitable candidate for an astrophysical black hole.",2111.02817v3
2022-02-09,External sources in a minimal and nonminimal CPT-odd Lorentz violating Maxwell electrodynamics,"This paper is devoted to the study of interactions between stationary
electromagnetic sources for the minimal and nonminimal CPT-odd photon sector of
the Standard Model Extension (SME), where we search mainly for physical
phenomena not present in the Maxwell electrodynamics. First we consider the
minimal CPT-odd sector, where the Lorentz violation is caused by the
Carroll-Field-Jackiw (CFJ) term, namely
$\sim\epsilon^{\mu\nu\alpha\beta}\left(k_{AF}\right)_{\mu}A_{\nu}F_{\alpha\beta}$,
and we treat the Lorentz breaking parameter $\left(k_{AF}\right)^{\mu}$
perturbatively up to second order. We consider effects due to the presence of
point-like charges, Dirac strings and point-like dipoles. In special, we
calculate the electromagnetic field produced outside the string and investigate
the so called Aharonov-Bohm bound states in Lorentz violation context. After,
we consider a model where the Lorentz violation is generated by the
higher-derivative version of the CFJ model, namely
$\sim\epsilon^{\mu\nu\alpha\beta}V_{\mu}A_{\nu}\Box F_{\alpha\beta}$, which is
a dimension five term of the CPT-odd sector of the nonminimal SME. For this
higher-derivative model, we obtain effects up to second order in $V^{\mu}$
related to the presence of point-like charges and a steady current line. We use
overestimated constrains for the Lorentz violation parameters in order to
investigate the physical relevance of some results found in atomic systems. We
also make an overestimate for the background vectors using experimental data
from the atomic electric field.",2202.04424v2
2022-05-18,Probing Lorentz-Invariance-Violation Induced Nonthermal Unruh Effect in Quasi-Two-Dimensional Dipolar Condensates,"The Unruh effect states an accelerated particle detector registers a thermal
response when moving through the Minkowski vacuum, and its thermal feature is
believed to be inseparable from Lorentz symmetry: Without the latter, the
former disappears. Here we propose to observe analogue circular Unruh effect
using an impurity atom in a quasi-two-dimensional Bose-Einstein condensate
(BEC) with dominant dipole-dipole interactions between atoms or molecules in
the ultracold gas. Quantum fluctuations in the condensate possess a Bogoliubov
spectrum $\omega_{\mathbf k}=c_0|{\mathbf k}|f(\hbar\,c_0|{\mathbf
k}|/M_\ast)$, working as an analogue Lorentz-violating quantum field with the
Lorentz-breaking scale $M_\ast$, and the impurity acts as an effective
Unruh-DeWitt detector thereof. When the detector travels close to the sound
speed, observation of the Unruh effect in our quantum fluid platform becomes
experimentally feasible. In particular, the deviation of the Bogoliubov
spectrum from the Lorentz-invariant case is highly engineerable through the
relative strength of the dipolar and contact interactions, and thus a viable
laboratory tool is furnished to experimentally investigate whether the thermal
characteristic of Unruh effect is robust to the breaking of Lorentz symmetry.",2205.08669v2
2022-08-03,"Holographic Complexity of LST and Single Trace $T\bar{T}$, $J\bar{T}$ and $T\bar{J}$ deformations","This work is an extension of our previous work [1] where we exploited
holography to compute the complexity characteristics of Little String Theory
(LST), a nonlocal, nongravitational field theory which flows to a local 2d CFT
in the IR under RG via an integrable irrelevant (TT) deformation. Here we look
at the more general LST obtained by UV deforming the 2d CFT by incorporating
Lorentz violating irrelevant JT and TJ deformations on top of TT deformation,
in an effort to capture the novel signatures of Lorentz violation (on top of
nonlocality) on quantum complexity. In anticipation of the fact that the dual
field theory is Lorentz violating, we compute the volume complexity in two
different Lorentz frames and the comparison is drawn between the results. It
turns out that for this system the nonlocality and Lorentz violation effects
are inextricably intertwined in the UV divergence structure of the quantum
complexity. The coefficients of the divergences carry the signature of Lorentz
boost violation. We also compute the subregion complexity which displays a
(Hagedorn) phase transition with the transition point being the same as that
for the phase transition of entanglement entropy [2]. These new results are
consistent with our previous work [1]. Null warped AdS3 is treated as an
interesting special case.",2208.02314v3
2022-10-08,Exploring Anisotropic Lorentz Invariance Violation from the Spectral-Lag Transitions of Gamma-Ray Bursts,"The observed spectral lags of gamma-ray bursts (GRBs) have been widely used
to explore possible violations of Lorentz invariance. However, these studies
were generally performed by concentrating on the rough time lag of a single
highest-energy photon and ignoring the intrinsic time lag at the source. A new
way to test nonbirefringent Lorentz-violating effects has been proposed by
analyzing the multi-photon spectral-lag behavior of a GRB that displays a
positive-to-negative transition. This method gives both a plausible description
of the intrinsic energy-dependent time lag and comparatively robust constraints
on Lorentz-violating effects. In this work, we conduct a systematic search for
Lorentz-violating photon dispersion from the spectral-lag transition features
of 32 GRBs. By fitting the spectral-lag data of these 32 GRBs, we place
constraints on a variety of isotropic and anisotropic Lorentz-violating
coefficients with mass dimension $d=6$ and $8$. While our dispersion
constraints are not competitive with existing bounds, they have the promise to
complement the full coefficient space.",2210.03897v1
2023-04-19,Planar Hall effect in topological Weyl and nodal line semimetals,"Using symmetry analysis and semiclassical Boltzmann equation, we
theoretically explore the planar Hall effect (PHE) in three-dimensional
materials. We demonstrate that PHE is a general phenomenon that can occur in
various systems regardless of band topology. Both the Lorentz force and Berry
curvature effects can induce significant PHE, and the leading contributions of
both effects linearly depend on the electric and magnetic fields. The Lorentz
force and Berry curvature PHE coefficient possess only antisymmetric and
symmetric parts, respectively. Both contributions respect the same crystalline
symmetry constraints but differ under time-reversal symmetry. Remarkably, for
topological Weyl semimetal, the Berry curvature PHE coefficient is a constant
that does not depends on the Fermi energy, while the Lorentz force contribution
linearly increases with the Fermi energy, resulting from the linear dispersion
of the Weyl point. Furthermore, we find that the PHE in topological nodal line
semimetals is mainly induced by the Lorentz force, as the Berry curvature in
these systems vanishes near the nodal line. Our study not only highlights the
significance of the Lorentz force in PHE, but also reveals its unique
characteristics, which will be beneficial for determining the Lorentz force
contribution experimentally.",2304.09768v3
2023-12-20,Explicit form for the most general Lorentz transformation revisited,"Explicit formulae for the $4\times 4$ Lorentz transformation matrices
corresponding to a pure boost and a pure three-dimensional rotation are very
well-known. Significantly less well-known is the explicit formula for a general
Lorentz transformation with arbitrary boost and rotation parameters. We revisit
this more general formula by presenting two different derivations. The first
derivation (which is somewhat simpler than previous ones appearing in the
literature) evaluates the exponential of a $4\times 4$ matrix $A$, where $GA$
is an arbitrary $4\times 4$ real antisymmetric matrix and $G$ is a diagonal
matrix corresponding to the Minkowski metric. The formula for $\exp A$ depends
only on the eigenvalues of $A$ and makes use of the Lagrange interpolating
polynomial. The second derivation exploits the assertion that the spinor
product $\eta^\dagger{\bar{\sigma}}^{\,\mu}\chi$ transforms as a Lorentz
four-vector, where $\chi$ and $\eta$ are two-component spinors. The advantage
of this derivation is that the formula for a general Lorentz transformation
$\Lambda$ reduces to the computation of the trace of a product of $2\times 2$
matrices. Both computations are shown to yield equivalent expressions for
$\Lambda$.",2312.12969v3
1996-09-10,The Damping Tail of CMB Anisotropies,"By decomposing the damping tail of CMB anisotropies into a series of transfer
functions representing individual physical effects, we provide ingredients that
will aid in the reconstruction of the cosmological model from small-scale CMB
anisotropy data. We accurately calibrate the model-independent effects of
diffusion and reionization damping which provide potentially the most robust
information on the background cosmology. Removing these effects, we uncover
model-dependent processes such as the acoustic peak modulation and
gravitational enhancement that can help distinguish between alternate models of
structure formation and provide windows into the evolution of fluctuations at
various stages in their growth.",9609079v1
1997-09-16,Lyman-alpha emission as a tool to study high redshift damped systems,"We report a quantitative study of the escape of Lyman-alpha photons from an
inhomogeneous optically thick medium that mimics the structure of damped
Lyman-alpha absorbers. Modeling the optically thick disk with 3 components
(massive stars and HII regions, dust, and neutral hydrogen), we study the
resulting emission line profile that may arise near the extended damped
absorption profile.",9709150v1
1997-10-17,The chemical evolution of galaxies causing damped Ly$α$ absorption,"We have compiled all available data on chemical abundances in damped Lyman
alpha absorption systems for comparison with results from our combined chemical
and spectrophotometric galaxy evolution models. Preliminary results from
chemically consistent calculations are in agreement with observations of damped
Ly$\alpha$ systems.",9710193v1
1998-01-26,Are Damped Lyman alpha Systems Rotating Disks ?,"We report on high spectral resolution observations of five damped Lyman alpha
systems whose line velocity profiles and abundances are analyzed. By combining
these data with information from the literature, we study the kinematics of the
low and high ionization phases of damped systems and discuss the possibility
that part of the motions is due to rotation.",9801243v1
2001-10-29,Damping of inhomogeneities in neutralino dark matter,"The lightest supersymmetric particle, most likely the neutralino, might
account for a large fraction of dark matter in the Universe. We show that the
primordial spectrum of density fluctuations in neutralino cold dark matter
(CDM) has a sharp cut-off due to two damping mechanisms: collisional damping
during the kinetic decoupling of the neutralinos at O(10 MeV) and free
streaming after last scattering of neutralinos. The cut-off in the primordial
spectrum defines a minimal mass for CDM objects in hierarchical structure
formation. For typical neutralino and sfermion masses the first gravitationally
bound neutralino clouds have masses above 10^(-6) M_\odot.",0110601v1
2002-08-03,Adiabatic Index of Dense Matter and Damping of Neutron Star Pulsations,"The adiabatic index Gamma_1 for perturbations of dense matter is studied
under various physical conditions which can prevail in neutron star cores. The
dependence of Gamma_1 on the composition of matter (in particular, on the
presence of hyperons), on the stellar pulsation amplitude, and on the baryon
superfluidity is analyzed. Timescales of damping of stellar pulsations are
estimated at different compositions, temperatures, and pulsation amplitudes.
Damping of pulsations by bulk viscosity in the neutron-star cores can prevent
the stars to pulsate with relative amplitudes > (1-15)% (depending on the
composition of matter).",0208078v1
2003-01-07,Damping of Neutron Star Shear Modes by Superfluid Friction,"The forced motion of superfluid vortices in shear oscillations of rotating
solid neutron star matter produces damping of the mode. A simple model of the
unpinning and repinning processes is described, with numerical calculations of
the consequent energy decay times. These are of the order of 1 s or more for
typical anomalous X-ray pulsars but become very short for the general
population of radio pulsars. The superfluid friction processes considered here
may also be significant for the damping of r-modes in rapidly rotating neutron
stars.",0301112v1
1999-05-06,Collective and chaotic motion in self-bound many-body systems,"We investigate the interplay of collective and chaotic motion in a classical
self-bound N-body system with two-body interactions. This system displays a
hierarchy of three well separated time scales that govern the onset of chaos,
damping of collective motion and equilibration. Comparison with a mean-field
problem shows that damping is mainly due to dephasing. The Lyapunov exponent,
damping and equilibration rates depend mildly on the system size N.",9905007v2
1997-05-12,Damping of Oscillations in Layer-by-Layer Growth,"We present a theory for the damping of layer-by-layer growth oscillations in
molecular beam epitaxy. The surface becomes rough on distances larger than a
layer coherence length which is substantially larger than the diffusion length.
The damping time can be calculated by a comparison of the competing roughening
and smoothening mechanisms. The dependence on the growth conditions,
temperature and deposition rate, is characterized by a power law. The
theoretical results are confirmed by computer simulations.",9705100v1
1999-09-17,Thermoelastic Damping in Micro- and Nano-Mechanical Systems,"The importance of thermoelastic damping as a fundamental dissipation
mechanism for small-scale mechanical resonators is evaluated in light of recent
efforts to design high-Q micrometer- and nanometer-scale electro-mechanical
systems (MEMS and NEMS). The equations of linear thermoelasticity are used to
give a simple derivation for thermoelastic damping of small flexural vibrations
in thin beams. It is shown that Zener's well-known approximation by a
Lorentzian with a single thermal relaxation time slightly deviates from the
exact expression.",9909271v1
2000-10-01,Super-Radiance and the Unstable Photon Oscillator,"If the damping of a simple harmonic oscillator from a thermally random force
is sufficiently strong, then the oscillator may become unstable. For a photon
oscillator (radiatively damped by electric dipole moments), the instability
leads to a low temperature Hepp-Lieb-Preparata super-radiant phase transition.
The stable oscillator regime is described by the free energy of the
conventional Casimir effect. The unstable (strongly damped) oscillator has a
free energy corresponding to Dicke super-radiance.",0010013v1
2001-08-07,Non-damped Acoustic Plasmon and Superconductivity in Single Wall Carbon Nanotubes,"We show that non-damped acoustic plasmons exist in single wall carbon
nanotubes (SWCNT) and propose that the non-damped acoustic plasmons may mediate
electron-electron attraction and result in superconductivity in the SWCNT. The
superconducting transition temperature Tc for the SWCNT (3,3) obtained by this
mechanism agrees with the recent experimental result (Z. K. Tang et al, Science
292, 2462(2001)). We also show that it is possible to get higher Tc up to 99 K
by doping the SWCNT (5,5).",0108124v2
2001-10-11,Enhanced Gilbert Damping in Thin Ferromagnetic Films,"Using a scattering matrix approach, the precession of the magnetization of a
ferromagnet is shown to transfer spins into adjacent normal metal layers. This
``pumping'' of spins slows down the precession corresponding to an enhanced
Gilbert damping factor in the Landau-Lifshitz equation. The damping is
expressed in terms of the scattering matrix of the ferromagnet-normal metal
interface, which is accessible to model and first-principles calculations. Our
estimates for permalloy thin films explain the trends observed in recent
experiments.",0110247v2
2001-12-16,The Damping of the Bose-Condensate Oscillations in a Trap at Zero Temperature,"We discuss an existence of the damping for the radial condensate oscillations
in a cylindric trap at zero temperature. The damping is a result of the
parametric resonance leading to energy transfer from the coherent condensate
oscillations to the longitudinal sound waves within a finite frequency
interval. The parametric resonance is due to the oscillations of the sound
velocity. The triggering amplitudes at zero temperature are associated with the
zero-point oscillations.",0112292v1
2002-02-11,Radiation Induced Landau-Lifshitz-Gilbert Damping in Ferromagnets,"The Landau-Lifshitz-Gilbert damping coefficient employed in the analysis of
spin wave ferromagnetic resonance is related to the electrical conductivity of
the sample. The changing magnetization (with time) radiates electromagnetic
fields. The electromagnetic energy is then absorbed by the sample and the
resulting heating effect describes magnetic dissipative damping. The
ferromagnetic resonance relaxation rate theoretically depends on the geometry
(shape and size) of the sample as well as temperature in agreement with
experiment.",0202181v1
2002-06-13,Beliaev damping of quasi-particles in a Bose-Einstein condensate,"We report a measurement of the suppression of collisions of quasi-particles
with ground state atoms within a Bose-Einstein condensate at low momentum.
These collisions correspond to Beliaev damping of the excitations, in the
previously unexplored regime of the continuous quasi-particle energy spectrum.
We use a hydrodynamic simulation of the expansion dynamics, with the Beliaev
damping cross-section, in order to confirm the assumptions of our analysis.",0206234v1
2002-06-28,Accidental suppression of Landau damping of the transverse breathing mode in elongated Bose-Einstein condensates,"We study transverse radial oscillations of an elongated Bose-Einstein
condensate using finite temperature simulations, in the context of a recent
experiment at ENS. We demonstrate the existence of a mode corresponding to an
in-phase collective oscillation of both the condensate and thermal cloud.
Excitation of this mode accounts for the very small damping rate observed
experimentally, and we find excellent quantitative agreement between experiment
and theory. In contrast to other condensate modes, interatomic collisions are
found to be the dominant damping mechanism in this case.",0206582v1
2004-04-19,Nonlinear response of superparamagnets with finite damping: an analytical approach,"The strongly damping-dependent nonlinear dynamical response of classical
superparamagnets is investigated by means of an analytical approach. Using
rigorous balance equations for the spin occupation numbers a simple approximate
expression is derived for the nonlinear susceptibility. The results are in good
agreement with those obtained from the exact (continued-fraction) solution of
the Fokker-Planck equation. The formula obtained could be of assistance in the
modelling of the experimental data and the determination of the damping
coefficient in superparamagnets.",0404445v1
2004-09-24,Minimal field requirement in precessional magnetization switching,"We investigate the minimal field strength in precessional magnetization
switching using the Landau-Lifshitz-Gilbert equation in under-critically damped
systems. It is shown that precessional switching occurs when localized
trajectories in phase space become unlocalized upon application of field
pulses. By studying the evolution of the phase space, we obtain the analytical
expression of the critical switching field in the limit of small damping for a
magnetic object with biaxial anisotropy. We also calculate the switching times
for the zero damping situation. We show that applying field along the medium
axis is good for both small field and fast switching times.",0409671v1
2005-03-03,Collapse of thermal activation in moderately damped Josephson junctions,"We study switching current statistics in different moderately damped
Josephson junctions: a paradoxical collapse of the thermal activation with
increasing temperature is reported and explained by interplay of two
conflicting consequences of thermal fluctuations, which can both assist in
premature escape and help in retrapping back into the stationary state. We
analyze the influence of dissipation on the thermal escape by tuning the
damping parameter with a gate voltage, magnetic field, temperature and an
in-situ capacitor.",0503067v1
2006-01-10,Voltage dependence of Landau-Lifshitz-Gilbert damping of a spin in a current driven tunnel junction,"We present a theory of Landau-Lifshitz-Gilbert damping $\alpha$ for a
localized spin ${\vec S}$ in the junction coupled to the conduction electrons
in both leads under an applied volatege $V$. We find the voltage dependence of
the damping term reflecting the energy dependence of the density of states. We
find the effect is linear in the voltage and cotrolled by particle-hole
asymmetry of the leads.",0601185v1
2006-03-13,Universal features of the defect-induced damping of lattice vibrations,"It is shown that any defect gives an Ohmic contribution to the damping of any
normal mode of the crystal lattice with nonzero wavevector which does not
vanish at zero temperature. This explains the large phason damping observed at
low temperatures in incommensurate phases, and might be a key factor to
understand the linear-in-$T$ specific heat observed in a number of real
dielectrics at low enough temperatures.",0603343v2
2006-04-25,Spin Precession and Avalanches,"In many magnetic materials, spin dynamics at short times are dominated by
precessional motion as damping is relatively small. In the limit of no damping
and no thermal noise, we show that for a large enough initial instability, an
avalanche can transition to an ergodic phase where the state is equivalent to
one at finite temperature, often above that for ferromagnetic ordering. This
dynamical nucleation phenomenon is analyzed theoretically. For small finite
damping the high temperature growth front becomes spread out over a large
region. The implications for real materials are discussed.",0604563v1
2007-02-11,Non-Markovian coherence dynamics of driven spin boson model: damped quantum beat or large amplitude coherence oscillation,"The dynamics of driven spin boson model is studied analytically by means of
the perturbation approach based on a unitary transformation. We gave the
analytical expression for the population difference and coherence of the two
level system. The results show that in the weak driven case, the population
difference present damped coherent oscillation (single or double frequency) and
the frequencies depend on the initial state. The coherence exhibit damped
oscillation with Rabi frequency. When driven field is strong enough, the
population difference exhibit undamped large-amplitude coherent oscillation.
The results easily return to the two extreme cases without dissipation or
without periodic driven.",0702268v1
2005-05-10,Highly Damped Quasinormal Modes of Generic Single Horizon Black Holes,"We calculate analytically the highly damped quasinormal mode spectra of
generic single-horizon black holes using the rigorous WKB techniques of
Andersson and Howls\cite{Andersson}. We thereby provide a firm foundation for
previous analysis, and point out some of their possible limitations. The
numerical coefficient in the real part of the highly damped frequency is
generically determined by the behavior of coupling of the perturbation to the
gravitational field near the origin, as expressed in tortoise coordinates. This
fact makes it difficult to understand how the famous $ln(3)$ could be related
to the quantum gravitational microstates near the horizon.",0505044v1
2006-05-01,Stability and quasinormal modes of the massive scalar field around Kerr black holes,"We find quasinormal spectrum of the massive scalar field in the background of
the Kerr black holes. We show that all found modes are damped under the
quasinormal modes boundary conditions when $\mu M$ is not large, thereby
implying stability of the massive scalar field. This complements the region of
stability determined by the Beyer inequality for large masses of the field. We
show that, similar to the case of a non-rotating black holes, the massive term
of the scalar field does not contribute in the regime of high damping. Thereby,
the high damping asymptotic should be the same as for the massless scalar
field.",0605013v1
1992-04-06,Comment on ``High Temperature Fermion Propagator -- Resummation and Gauge Dependence of the Damping Rate'',"Baier et al. have reported the damping rate of long-wavelength fermionic
excitations in high-temperature QED and QCD to be gauge-fixing-dependent even
within the resummation scheme due to Braaten and Pisarski. It is shown that
this problem is caused by the singular nature of the on-shell expansion of the
fermion self-energy in the infra-red. Its regularization reveals that the
alleged gauge dependence pertains to the residue rather than the pole of the
fermion propagator, so that in particular the damping constant comes out
gauge-independent, as it should.",9204210v1
1993-02-09,Damping rates for moving particles in hot QCD,"Using a program of perturbative resummation I compute the damping rates for
fields at nonzero spatial momentum to leading order in weak coupling in hot
$QCD$. Sum rules for spectral densities are used to simplify the calculations.
For massless fields the damping rate has an apparent logarithmic divergence in
the infrared limit, which is cut off by the screening of static magnetic fields
(``magnetic mass''). This demonstrates how at high temperature even
perturbative quantities are sensitive to nonperturbative phenomenon.",9302242v1
1994-04-21,Is \lq\lq Heavy Quark Damping Rate Puzzle'' in Hot QCD Really the Puzzle?,"Within the framework of perturbative resummation scheme of Pisarski and
Braaten, the decay- or damping-rate of a moving heavy quark (muon) to leading
order in weak coupling in hot QCD (QED) is examined. Although, as is well
known, the conventionally-defined damping rate diverges logarithmically at the
infrared limit, shown is that no such divergence appears in the physically
measurable decay rate. The cancellation occurs between the contribution from
the \lq\lq real'' decay diagram and the contribution from the diagrams with
\lq\lq thermal radiative correction''.",9404318v1
1996-01-12,Damping Rate of a Scalar Particle in Hot Scalar QED,"In contrast to the damping of partons in a quark-gluon plasma, the damping of
a scalar particle in a hot scalar QED plasma can be calculated to leading order
for the whole momentum range using the Braaten-Pisarski method. In this way the
evolution of the logarithmic infrared singularity caused by the exchange of a
transverse photon from soft to hard momenta can be studied.",9601254v1
1996-09-17,Damping Rate of Quasiparticles in Degenerate Ultrarelativistic Plasmas,"We compute the damping rate of a fermion in a dense relativistic plasma at
zero temperature. Just above the Fermi sea, the damping rate is dominated by
the exchange of soft magnetic photons (or gluons in QCD) and is proportional to
$(E-\mu)$, where E is the fermion energy and $\mu$ the chemical potential. We
also compute the contribution of soft electric photons and of hard photons. As
in the nonrelativistic case, the contribution of longitudinal photons is
proportional to $(E-\mu)^2$, and is thus non leading in the relativistic case.",9609369v1
1997-05-28,Classical Statistical Mechanics and Landau Damping,"We study the retarded response function in scalar $\phi^4$-theory at finite
temperature. We find that in the high-temperature limit the imaginary part of
the self-energy is given by the classical theory to leading order in the
coupling. In particular the plasmon damping rate is a purely classical effect
to leading order, as shown by Aarts and Smit. The dominant contribution to
Landau damping is given by the propagation of classical fields in a heat bath
of non-interacting fields.",9705452v1
1997-12-01,A potential infrared problem with the damping rates for gluons with soft momentum in hot QCD,"We calculate the damping rate $\gamma_l$ for longitudinal gluons with zero
momentum in finite high temperature QCD and show that some of its contributing
terms are infrared divergent. This is in contrast with the expectation that
this damping rate is to be equal to the corresponding one $\gamma_t$ for
transverse gluons which is known to be finite. Our calculation was motivated by
the fact that similar divergent terms occur when we calculated in a previous
work $\gamma_t$ to order $ p^2$, p being the momentum of the gluon. After we
present our results, we briefly discuss them.",9712210v1
1998-04-21,The Plasmon Damping Rate for T -> T_C,"The plasmon damping rate in scalar field theory is computed close to the
critical temperature. It is shown that the divergent result obtained in
perturbation theory is a consequence of neglecting the thermal renormalization
of the coupling. Taking this effect into account, a vanishing damping rate is
obtained, leading to the critical slowing down of the equilibration process.",9804351v2
1998-10-06,Self-consistent Study on Color Transport in the Quark Gluon Plasma at Finite Chemical Potential,"We calculate the relaxation time self-consistently to study the damping of
collective color modes and the color conductivity in a QGP by deriving
self-consistent equations for the damping rates of gluons and quarks to leading
order QCD by TFD including a chemical potential for quarks. We show that the
damping rates are not sensitive to the chemical potential whereas color
conductivity is enhanced considerably.",9810256v1
1999-02-19,The problem of nonlinear Landau damping in quark-gluon plasma,"On the basis of the semiclassical equations for quark-gluon plasma (QGP) and
Yang-Mills equation, the generalized kinetic equation for waves with regard to
its interaction is obtained. The physical mechanisms defining nonlinear
scattering of a plasmon by QGP particles are analysed. The problem on a
connection of nonlinear Landau damping rate of longitudinal oscillation with
damping rate, obtained on the basis of hard thermal loops approximation, is
considered.",9902397v2
1999-07-21,A Slavnov-Taylor identity and equality of damping rates for static transverse and longitudinal gluons in hot QCD,"A Slavnov-Taylor identity is derived for the gluon polarization tensor in hot
QCD. We evaluate its implications for damping of gluonic modes in the plasma.
Applying the identity to next to the leading order in hard-thermal-loop
resummed perturbation theory, we derive the expected equality of damping rates
for static transverse and longitudinal (soft) gluons. This is of interest also
in view of deviating recent reports of $\gamma_t(p=0)\neq\gamma_l(p=0)$ based
on a direct calculation of $\gamma_l(p=0)$.",9907439v1
2000-09-15,Fermion Damping Rate Effects in Cold Dense Matter,"We review the non-Fermi or marginal liquid behavior of a relativistic QED
plasma. In this medium a quasiparticle has a damping rate that depends linearly
on the distance between its energy and the Fermi surface. We stress that this
dependence is due to the long-range character of the magnetic interactions in
the medium. Finally, we study how the quark damping rate modifies the gap
equation of color superconductivity, reducing the value of the gap at the Fermi
surface.",0009182v1
2001-07-19,Photon Damping Caused by Electron-Positron Pair Production in a Strong Magnetic Field,"Damping of an electromagnetic wave in a strong magnetic field is analyzed in
the kinematic region near the threshold of electron-positron pair production.
Damping of the electromagnetic field is shown to be noticeably nonexponential
in this region. The resulting width of the photon $\gamma \to e^+ e^-$ decay is
considerably smaller than previously known results.",0107217v1
2004-09-27,Damping of electromagnetic waves due to electron-positron pair production,"The problem of the backreaction during the process of electron-positron pair
production by a circularly polarized electromagnetic wave propagating in a
plasma is investigated. A model based on the relativistic Boltzmann-Vlasov
equation with a source term corresponding to the Schwinger formula for the pair
creation rate is used. The damping of the wave, the nonlinear up-shift of its
frequency due to the plasma density increase and the effect of the damping on
the wave polarization and on the background plasma acceleration are
investigated as a function of the wave amplitude.",0409301v1
2005-10-25,Infrared behavior of the dispersion relations in high-temperature scalar QED,"We investigate the infrared properties of the next-to-leading-order
dispersion relations in scalar quantum electrodynamics at high temperature in
the context of hard-thermal-loop perturbation theory. Specifically, we
determine the damping rate and the energy for scalars with ultrasoft momenta.
We show by explicit calculations that an early external-momentum expansion,
before the Matsubara sum is performed, gives exactly the same result as a late
one. The damping rate is obtained up to fourth order included in the ultrasoft
momentum and the energy up to second order. The damping rate is found sensitive
in the infrared whereas the energy not.",0510330v1
2006-11-09,Lepton asymmetry in the primordial gravitational wave spectrum,"Effects of neutrino free streaming is evaluated on the primordial spectrum of
gravitational radiation taking both neutrino chemical potential and masses into
account. The former or the lepton asymmetry induces two competitive effects,
namely, to increase anisotropic pressure, which damps the gravitational wave
more, and to delay the matter-radiation equality time, which reduces the
damping. The latter effect is more prominent and a large lepton asymmetry would
reduce the damping. We may thereby be able to measure the magnitude of lepton
asymmetry from the primordial gravitational wave spectrum.",0611121v1
2005-03-17,A New Approach to Canonical Quantization of the Radiation Damping,"Inspired in some works about quantization of dissipative systems, in
particular of the damped harmonic oscillator\cite{MB,RB,12}, we consider the
dissipative system of a charge interacting with its own radiation, which
originates the radiation damping (RD). Using the indirect Lagrangian
representation we obtained a Lagrangian formalism with a Chern-Simons-like
term. A Hamiltonian analysis is also done, what leads to the quantization of
the system.",0503135v1
2003-09-15,Eigenfrequencies and expansions for damped wave equations,"We study eigenfrequencies and propagator expansions for damped wave equations
on compact manifolds. Under the assumption of geometric control, the propagator
is shown to admit an expansion in terms of finitely many eigenmodes near the
real axis, with an error term exponentially decaying in time. In the presence
of a nondegenerate elliptic closed geodesic not meeting the support of the
damping coefficient, we show that there exists a sequence of eigenfrequencies
converging rapidly to the real axis. In the case of Zoll manifolds, we show
that the propagator can be expanded in terms of clusters of the
eigenfrequencies in the entire spectral band.",0309250v1
2004-06-02,Instability results for the damped wave equation in unbounded domains,"We extend some previous results for the damped wave equation in bounded
domains in Euclidean spaces to the unbounded case. In particular, we show that
if the damping term is of the form $\alpha a$ with bounded $a$ taking on
negative values on a set of positive measure, then there will always exist
unbounded solutions for sufficiently large positive $\alpha$.
  In order to prove these results, we generalize some existing results on the
asymptotic behaviour of eigencurves of one-parameter families of Schrodinger
operators to the unbounded case, which we believe to be of interest in their
own right.",0406041v1
1997-07-20,Effects of gluon damping rate on the viscosity coefficient of the quark-gluon plasma at finite chemical potential,"By considering the Debye screening and damping rate of gluons, the viscosity
coefficient of the quark-gluon plasma was evaluated via real-time finite
temperature QCD in the relaxation time approximation at finite temperature and
chemical potential . The results show that both the damping rate and the
chemical potential cause considerable enhancements to the viscosity coefficient
of hot dense quark-gluon plasma.",9707033v1
2002-12-11,Rotational Damping and Compound Formation in Warm Rotating Nuclei,"The rotational damping width \Gamma_{rot} and the compound damping width
\Gamma_{comp} are two fundamental quantities that characterize rapidly rotating
compound nuclei having finite thermal excitation energy. A two-component
structure in the strength function of consecutive E2 transitions reflects the
two widths, and it causes characteristic features in the double and triple
gamma-ray spectra. We discuss a new method to extract experimentally values of
\Gamma_{rot} and \Gamma_{comp}. The first preliminary result of this method is
presented.",0212050v1
2003-07-27,Chaos and rotational damping in particle-rotor model,"The onset of chaos and the mechanism of rotational damping are studied in an
exactly soluble particle-rotor model. It is shown that the degree of chaoticity
as inferred from the statistical measures is closely related to the onset of
rotational damping obtained using the model Hamiltonian.",0307104v2
1997-07-10,Supersymmetric partner chirping of Newtonian free damping,"We connect the classical free damping cases by means of Rosner's construction
in supersymmetric quantum mechanics. Starting with the critical damping, one
can obtain in the underdamping case a chirping of instantaneous physical
frequency \omega ^{2}(t) \propto \omega_{u}^{2}sech^2(\omega_{u}t), whereas in
the overdamped case the ""chirping"" is of the (unphysical) type \omega
^{2}(t)\propto\omega_{o}^{2}sec^{2}(\omega_{o}t), where \omega_{u}$ and
$\omega_{o} are the underdamped and overdamped frequency parameters,
respectively",9707012v4
2000-04-10,Ermakov-Lewis angles for one-parameter supersymmetric families of Newtonian free damping modes,"We apply the Ermakov-Lewis procedure to the one-parameter damped modes
\tilde{y} recently introduced by Rosu and Reyes, which are related to the
common Newtonian free damping modes y by the general Riccati solution [H.C.
Rosu and M. Reyes, Phys. Rev. E 57, 4850 (1998), physics/9707019]. In
particular, we calculate and plot the angle quantities of this approach that
can help to distinguish these modes from the common y modes",0004014v4
2002-10-29,Model of Internal Friction Damping in Solids,"A model for harmonic oscillator damping due to the internal friction of
solids has been developed, based on considerations of a long period pendulum.
The assumption of a complex elastic modulus to describe stress-strain
hysteresis in the support structure of the pendulum yields an expression for
the figure of merit Q that agrees with many experiments involving material
damping. As such, the approximations of this linear model stand in contrast
with common theory.",0210121v1
2003-06-11,Nonlinear Damping of the 'Linear' Pendulum,"This study shows that typical pendulum dynamics is far from the simple
equation of motion presented in textbooks. A reasonably complete damping model
must use nonlinear terms in addition to the common linear viscous expression.
In some cases a nonlinear substitute for assumed linear damping may be more
appropriate. Even for exceptional cases where all nonlinearity may be ignored,
it is shown that viscous dissipation involves subtleties that can lead to huge
errors when ignored.",0306081v1
2003-07-02,Harmonic Oscillator Potential to describe Internal Dissipation,"Assuming that a constant potential energy function has meaning for a
dissipated harmonic oscillator, then an important issue is the time dependence
of the turning points. Turning point studies demonstrate that the common model
of external (viscous) damping fails to properly describe those many systems
where structural (internal friction) damping is the most important source of
dissipation. For internal friction damping, the better model of potential
energy is one in which the function is not stationary.",0307016v1
2004-08-19,Beyond the Linear Damping Model for Mechanical Harmonic Oscillators,"The steady state motion of a folded pendulum has been studied using
frequencies of drive that are mainly below the natural (resonance) frequency of
the instrument. Although the free-decay of this mechanical oscillator appears
textbook exponential, the steady state behavior of the instrument for
sub-resonance drive can be remarkably complex. Although the response cannot be
explained by linear damping models, the general features can be understood with
the nonlinear, modified Coulomb damping model developed by the author.",0408091v1
1998-01-28,Phenomenological damping in trapped atomic Bose-Einstein condensates,"The method of phenomenological damping developed by Pitaevskii for
superfluidity near the $\lambda$ point is simulated numerically for the case of
a dilute, alkali, inhomogeneous Bose-condensed gas near absolute zero. We study
several features of this method in describing the damping of excitations in a
Bose-Einstein condensate. In addition, we show that the method may be employed
to obtain numerically accurate ground states for a variety of trap potentials.",9801064v1
1998-04-06,Optimal quantum codes for preventing collective amplitude damping,"Collective decoherence is possible if the departure between quantum bits is
smaller than the effective wave length of the noise field. Collectivity in the
decoherence helps us to devise more efficient quantum codes. We present a class
of optimal quantum codes for preventing collective amplitude damping to a
reservoir at zero temperature. It is shown that two qubits are enough to
protect one bit quantum information, and approximately $L+ 1/2 \log_2((\pi
L)/2)$ qubits are enough to protect $L$ qubit information when $L$ is large.
For preventing collective amplitude damping, these codes are much more
efficient than the previously-discovered quantum error correcting or avoiding
codes.",9804014v1
2000-01-12,Antibunching effect of the radiation field in a microcavity with a mirror undergoing heavily damping oscillation,"The interaction between the radiation field in a microcavity with a mirror
undergoing damping oscillation is investigated. Under the heavily damping
cases, the mirror variables are adiabatically eliminated.
  The the stationary conditions of the system are discussed. The small
fluctuation approximation around steady values is applied to analysis the
antibunching effect of the cavity field. The antibunching condition is given
under two limit cases.",0001036v1
2000-03-29,Disagreement between correlations of quantum mechanics and stochastic electrodynamics in the damped parametric oscillator,"Intracavity and external third order correlations in the damped nondegenerate
parametric oscillator are calculated for quantum mechanics and stochastic
electrodynamics (SED), a semiclassical theory. The two theories yield greatly
different results, with the correlations of quantum mechanics being cubic in
the system's nonlinear coupling constant and those of SED being linear in the
same constant. In particular, differences between the two theories are present
in at least a mesoscopic regime. They also exist when realistic damping is
included. Such differences illustrate distinctions between quantum mechanics
and a hidden variable theory for continuous variables.",0003131v1
2002-02-15,Decoherence of Quantum Damped Oscillators,"Quantum dissipation is studied within two model oscillators, the
Caldirola-Kanai (CK) oscillator as an open system with one degree of freedom
and the Bateman-Feshbach-Tikochinsky (BFT) oscillator as a closed system with
two degrees of freedom. Though these oscillators describe the same classical
damped motion, the CK oscillator retains the quantum coherence, whereas the
damped subsystem of the BFT oscillator exhibits both quantum decoherence and
classical correlation. Furthermore the amplified subsystem of the BFT
oscillator shows the same degree of quantum decohernce and classical
correlation.",0202089v1
2002-12-05,Time correlated quantum amplitude damping channel,"We analyze the problem of sending classical information through qubit
channels where successive uses of the channel are correlated. This work extends
the analysis of C. Macchiavello and G. M. Palma to the case of a non-Pauli
channel - the amplitude damping channel. Using the channel description outlined
in S. Daffer, et al, we derive the correlated amplitude damping channel. We
obtain a similar result to C. Macchiavello and G. M. Palma, that is, that under
certain conditions on the degree of channel memory, the use of entangled input
signals may enhance the information transmission compared to the use of product
input signals.",0212032v1
2003-09-29,Damping rates of the atomic velocity in Sisyphus cooling,"We present a theoretical and experimental study of the damping process of the
atomic velocity in Sisyphus cooling. The relaxation rates of the atomic kinetic
temperature are determined for a 3D lin$\perp$lin optical lattice. We find that
the damping rates of the atomic temperature depend linearly on the optical
pumping rate, for a given depth of the potential wells. This is at variance
with the behavior of the friction coefficient as calculated from the spatial
diffusion coefficients within a model of Brownian motion. The origin of this
different behavior is identified by distinguishing the role of the trapped and
traveling atoms.",0309209v1
2005-06-01,Quantum damped oscillator I: dissipation and resonances,"Quantization of a damped harmonic oscillator leads to so called Bateman's
dual system. The corresponding Bateman's Hamiltonian, being a self-adjoint
operator, displays the discrete family of complex eigenvalues. We show that
they correspond to the poles of energy eigenvectors and the corresponding
resolvent operator when continued to the complex energy plane. Therefore, the
corresponding generalized eigenvectors may be interpreted as resonant states
which are responsible for the irreversible quantum dynamics of a damped
harmonic oscillator.",0506007v1
2005-10-19,The damped harmonic oscillator in deformation quantization,"We propose a new approach to the quantization of the damped harmonic
oscillator in the framework of deformation quantization. The quantization is
performed in the Schr\""{o}dinger picture by a star-product induced by a
modified ""Poisson bracket"". We determine the eigenstates in the damped regime
and compute the transition probability between states of the undamped harmonic
oscillator after the system was submitted to dissipation.",0510150v1
2006-04-28,The characteristic function of optical evolution,"The master equation of quantum optical density operator is transformed to the
equation of characteristic function. The parametric amplification and amplitude
damping as well as the phase damping are considered. The solution for the most
general initial quantum state is obtained for parametric amplification and
amplitude damping. The purity of one mode Gaussian system and the entanglement
of two mode Gaussian system are studied.",0604208v4
2007-01-13,Wave-particle duality in the damped harmonic oscillator,"Quantization of the damped harmonic oscillator is taken as leitmotiv to
gently introduce elements of quantum probability theory for physicists. To this
end, we take (graduate) students in physics as entry level and explain the
physical intuition and motivation behind the, sometimes overwhelming, math
machinery of quantum probability theory.
  The main text starts with the quantization of the (undamped) harmonic
oscillator from the Heisenberg and Schroedinger point of view. We show how both
treatments are special instances of a quantum probabilistic quantization
procedure: the second quantization functor. We then apply the second
quantization functor to the damped harmonic oscillator and interpret the
quantum dynamics of the position and energy operator as stochastic processes.",0701082v1
2007-04-11,Time dependence of joint entropy of oscillating quantum systems,"The time dependent entropy (or Leipnik's entropy) of harmonic and damped
harmonic oscillators is extensively investigated by using time dependent wave
function obtained by the Feynman path integral method. Our results for simple
harmonic oscillator are in agrement with the literature. However, the joint
entropy of damped harmonic oscillator shows remarkable discontinuity with time
for certain values of damping factor. According to the results, the envelop of
the joint entropy curve increases with time monotonically. This results is the
general properties of the envelop of the joint entropy curve for quantum
systems.",0704.1370v3
2007-06-30,The squeezed generalized amplitude damping channel,"Squeezing of a thermal bath introduces new features absent in an open quantum
system interacting with an uncorrelated (zero squeezing) thermal bath. The
resulting dynamics, governed by a Lindblad-type evolution, extends the concept
of a generalized amplitude damping channel, which corresponds to a dissipative
interaction with a purely thermal bath. Here we present the Kraus
representation of this map, which we call the squeezed generalized amplitude
damping channel. As an application of this channel to quantum information, we
study the classical capacity of this channel.",0707.0059v2
2007-07-09,Memory in a nonlocally damped oscillator,"We analyze the new equation of motion for the damped oscillator. It differs
from the standard one by a damping term which is nonlocal in time and hence it
gives rise to a system with memory. Both classical and quantum analysis is
performed. The characteristic feature of this nonlocal system is that it breaks
local composition low for the classical Hamiltonian dynamics and the
corresponding quantum propagator.",0707.1199v2
2007-07-20,Dynamics of Bloch Oscillations in Disordered Lattice Potentials,"We present a detailed analysis of the dynamics of Bloch oscillations of
Bose-Einstein condensates in disordered lattice potentials. Due to the disorder
and the interparticle interactions these oscillations undergo a dephasing,
reflected in a damping of the center of mass oscillations, which should be
observable under realistic experimental conditions. The interplay between
interactions and disorder is far from trivial, ranging from an
interaction-enhanced damping due to modulational instability for strong
interactions, to an interaction-reduced damping due to a dynamical screening of
the disorder potential.",0707.3131v1
2007-09-14,Damping of field-induced chemical potential oscillations in ideal two-band compensated metals,"The field and temperature dependence of the de Haas-van Alphen oscillations
spectrum is studied for an ideal two-dimensional compensated metal. It is shown
that the chemical potential oscillations, involved in the frequency
combinations observed in the case of uncompensated orbits, are strongly damped
and can even be suppressed when the effective masses of the electron- and
hole-type orbits are the same. When magnetic breakdown between bands occurs,
this damping is even more pronounced and the Lifshits-Kosevich formalism
accounts for the data in a wide field range.",0709.2223v2
2007-09-14,Update on Ion Studies,"The effect of ions has received one of the highest priorities in R&D for the
damping rings of the International Linear Collider(ILC). It is detrimental to
the performance of the electron damping ring. In this note, an update
concerning the ion studies for the ILC damping ring is given. We investigate
the gap role and irregular fill pattern in the ring.The ion density reduction
in different fills is calculated analytically. Simulation results are also
presented.",0709.2248v1
2007-10-03,Stability of a Nonlinear Axially Moving String With the Kelvin-Voigt Damping,"In this paper, a nonlinear axially moving string with the Kelvin-Voigt
damping is considered. It is proved that the string is stable, i.e., its
transversal displacement converges to zero when the axial speed of the string
is less than a certain critical value. The proof is established by showing that
a Lyapunov function corresponding to the string decays to zero exponentially.
It is also shown that the string displacement is bounded when a bounded
distributed force is applied to it transversally. Furthermore, a few open
problems regarding the stability and stabilization of strings with the
Kelvin-Voigt damping are stated.",0710.0872v1
2007-10-15,General Solution of the Quantum Damped Harmonic Oscillator,"In this paper the general solution of the quantum damped harmonic oscillator
is given.",0710.2724v4
2008-02-21,Identification of Test Structures for Reduced Order Modeling of the Squeeze Film Damping in Mems,"In this study the dynamic behaviour of perforated microplates oscillating
under the effect of squeeze film damping is analyzed. A numerical approach is
adopted to predict the effects of damping and stiffness transferred from the
surrounding ambient air to oscillating structures ; the effect of hole's cross
section and plate's extension is observed. Results obtained by F.E.M. models
are compared with experimental measurements performed by an optical
interferometric microscope.",0802.3076v1
2008-03-14,Current-induced noise and damping in non-uniform ferromagnets,"In the presence of spatial variation of the magnetization direction, electric
current noise causes a fluctuating spin-transfer torque that increases the
fluctuations of the ferromagnetic order parameter. By the
fluctuation-dissipation theorem, the equilibrium fluctuations are related to
the magnetization damping, which in non-uniform ferromagnets acquires a
nonlocal tensor structure. In biased ferromagnets, shot noise can become the
dominant contribution to the magnetization noise at low temperatures.
Considering spin spirals as a simple example, we show that the current-induced
noise and damping is significant.",0803.2175v1
2008-04-23,Ion acoustic waves in the plasma with the power-law q-distribution in nonextensive statistics,"We investigate the dispersion relation and Landau damping of ion acoustic
waves in the collisionless magnetic-field-free plasma if it is described by the
nonextensive q-distributions of Tsallis statistics. We show that the increased
numbers of superthermal particles and low velocity particles can explain the
strengthened and weakened modes of Landau damping, respectively, with the
q-distribution. When the ion temperature is equal to the electron temperature,
the weakly damped waves are found to be the distributions with small values of
q.",0804.3732v1
2008-08-05,"Radiation damping, noncommutativity and duality","In this work, our main objective is to construct a N=2 supersymmetric
extension of the nonrelativistic $(2+1)$-dimensional model describing the
radiation damping on the noncommutative plane with scalar (electric) and vector
(magnetic) interactions by the N=2 superfield technique. We also introduce a
dual equivalent action to the radiation damping one using the Noether
procedure.",0808.0694v2
2008-08-28,Gilbert Damping in Conducting Ferromagnets II: Model Tests of the Torque-Correlation Formula,"We report on a study of Gilbert damping due to particle-hole pair excitations
in conducting ferromagnets. We focus on a toy two-band model and on a four-band
spherical model which provides an approximate description of ferromagnetic
(Ga,Mn)As. These models are sufficiently simple that disorder-ladder-sum vertex
corrections to the long-wavelength spin-spin response function can be summed to
all orders. An important objective of this study is to assess the reliability
of practical approximate expressions which can be combined with electronic
structure calculations to estimate Gilbert damping in more complex systems.",0808.3923v1
2008-10-06,Local existence and exponential growth for a semilinear damped wave equation with dynamic boundary conditions,"In this paper we consider a multi-dimensional damped semiliear wave equation
with dynamic boundary conditions, related to the Kelvin-Voigt damping. We
firstly prove the local existence by using the Faedo-Galerkin approximations
combined with a contraction mapping theorem. Secondly, the exponential growth
of the energy and the $L^p$ norm of the solution is presented.",0810.1013v1
2008-11-20,An explanation for the pseudogap of high-temperature superconductors based on quantum optics,"We first explain the pseudogap of high-temperature superconductivity based on
an approach of quantum optics. After introducing a damping factor for the
lifetime $\tau$ of quasiparticles, the superconducting dome is naturally
produced, and the pseudogap is the consequence of pairing with damped
coherence. We derive a new expression of Ginzburg-Landau free energy density,
in which a six-order term due to decoherence damping effect is included.
Without invoking any microscopic pairing mechanism, this approach provides a
simple universal equation of second-order phase transition, which can be
reduced to two well-known empirical scaling equations: the superconducting dome
Presland-Tallon equation, and the normal-state pseudogap crossover temperature
$T^{*}$ line.",0811.3262v1
2008-12-18,Exponential decay for solutions to semilinear damped wave equation,"This paper is concerned with decay estimate of solutions to the semilinear
wave equation with strong damping in a bounded domain. Introducing an
appropriate Lyaponuv function, we prove that when the damping is linear, we can
find initial data, for which the solution decays exponentially. This result
improves an early one in an article of Gazzola and Squassina.",0812.3637v3
2009-05-27,Difference between penetration and damping lengths in photonic crystal mirrors,"Different mirror geometries in two-dimensional photonic crystal slabs are
studied with fully-vectorial calculations. We compare their optical properties
and, in particular, we show that, for heterostructure mirrors, the penetration
length associated with the delay induced by distributed reflection is not
correlated to the characteristic damping length of the electromagnetic energy
distribution in the mirror. This unexpected result evidences that the usual
trade-off between short damping lengths and large penetration lengths that is
classically encountered in distributed Bragg reflectors can be overcome with
carefully designed photonic crystal structures.",0905.4449v2
2009-06-01,Exponential Decay Rates for the Damped Korteweg-de Vries Type Equation,"The exponential decay rate of $L^2-$norm related to the Korteweg-de Vries
equation with localized damping posed on whole real line will be established.
In addition, by using classical arguments we determine the $H^1-$norm of the
solution associated to Korteweg-de Vries equation with damping in whole domain,
can not have a decay property for an arbitrary initial data.",0906.0285v2
2009-07-02,Damping and decoherence of a nanomechanical resonator due to a few two level systems,"We consider a quantum model of a nanomechanical flexing beam resonator
interacting with a bath comprising a few damped tunneling two level systems
(TLS's). In contrast with a resonator interacting bilinearly with an ohmic free
oscillator bath (modeling clamping loss, for example), the mechanical resonator
damping is amplitude dependent, while the decoherence of quantum superpositions
of mechanical position states depends only weakly on their spatial separation.",0907.0431v1
2009-07-29,High performance single-error-correcting quantum codes for amplitude damping,"We construct families of high performance quantum amplitude damping codes.
All of our codes are nonadditive and most modestly outperform the best possible
additive codes in terms of encoded dimension. One family is built from
nonlinear error-correcting codes for classical asymmetric channels, with which
we systematically construct quantum amplitude damping codes with parameters
better than any prior construction known for any block length n > 7 except
n=2^r-1. We generalize this construction to employ classical codes over GF(3)
with which we numerically obtain better performing codes up to length 14.
Because the resulting codes are of the codeword stabilized (CWS) type, easy
encoding and decoding circuits are available.",0907.5149v1
2009-10-12,Suppression of Landau damping via electron band gap,"The pondermotive potential in the X-ray Raman compression can generate an
electron band gap which suppresses the Landau damping. The regime is identified
where a Langmuir wave can be driven without damping in the stimulated Raman
compression. It is shown that the partial wave breaking and the frequency
detuning due to the trapped particles would be greatly reduced.",0910.2196v3
2009-10-27,Rabi type oscillations in damped single 2D-quantum dot,"We present a quantized model of harmonically confined dot atom with inherent
damping in the presence of a transverse magnetic field. The model leads to a
non hermitian Hamiltonian in real coordinate. We have analytically studied the
effects that damping has on the Rabi type oscillations of the system. The model
explains the decoherence of Rabi oscillation in a Josephson Junction.",0910.5184v1
2010-01-26,Effect of spin-conserving scattering on Gilbert damping in ferromagnetic semiconductors,"The Gilbert damping in ferromagnetic semiconductors is theoretically
investigated based on the $s$-$d$ model. In contrast to the situation in
metals, all the spin-conserving scattering in ferromagnetic semiconductors
supplies an additional spin relaxation channel due to the momentum dependent
effective magnetic field of the spin-orbit coupling, thereby modifies the
Gilbert damping. In the presence of a pure spin current, we predict a new
contribution due to the interplay of the anisotropic spin-orbit coupling and a
pure spin current.",1001.4576v1
2010-03-08,A single-ion nonlinear mechanical oscillator,"We study the steady state motion of a single trapped ion oscillator driven to
the nonlinear regime. Damping is achieved via Doppler laser-cooling. The ion
motion is found to be well described by the Duffing oscillator model with an
additional nonlinear damping term. We demonstrate a unique ability of tuning
both the linear as well as the nonlinear damping coefficients by controlling
the cooling laser parameters. Our observations open a way for the investigation
of nonlinear dynamics on the quantum-to-classical interface as well as
mechanical noise squeezing in laser-cooling dynamics.",1003.1577v1
2010-03-09,Damping of Nanomechanical Resonators,"We study the transverse oscillatory modes of nanomechanical silicon nitride
strings under high tensile stress as a function of geometry and mode index m <=
9. Reproducing all observed resonance frequencies with classical elastic theory
we extract the relevant elastic constants. Based on the oscillatory local
strain we successfully predict the observed mode-dependent damping with a
single frequency independent fit parameter. Our model clarifies the role of
tensile stress on damping and hints at the underlying microscopic mechanisms.",1003.1868v1
2010-03-24,Global attractors for strongly damped wave equations with displacement dependent damping and nonlinear source term of critical exponent,"In this paper the long time behaviour of the solutions of 3-D strongly damped
wave equation is studied. It is shown that the semigroup generated by this
equation possesses a global attractor in H_{0}^{1}(\Omega)\times L_{2}(\Omega)
and then it is proved that this global attractor is a bounded subset of
H^{2}(\Omega)\times H^{2}(\Omega) and also a global attractor in
H^{2}(\Omega)\cap H_{0}^{1}(\Omega)\times H_{0}^{1}(\Omega).",1003.4760v3
2010-04-12,Entanglement properties of optical coherent states under amplitude damping,"Through concurrence, we characterize the entanglement properties of optical
coherent-state qubits subject to an amplitude damping channel. We investigate
the distillation capabilities of known error correcting codes and obtain upper
bounds on the entanglement depending on the non-orthogonality of the coherent
states and the channel damping parameter. This work provides a first, full
quantitative analysis of these photon-loss codes which are naturally
reminiscent of the standard qubit codes against Pauli errors.",1004.1931v2
2010-06-09,Self frequency-locking of a chain of oscillators,"The paper studies the vibrational modes of a slightly damped uniform chain,
with n masses coupled by elastic forces. It will be shown that, for certain
lengths of the chain, that is for certain values of n, the damping of one of
the masses at a specific position in the chain is able to constrain the
vibration of the system to oscillate at a specific frequency. The damped mass
turns out to be a node of the chain, subdividing it in two parts. This node can
be considered as the synchronization element of the two subchains. As a
consequence the oscillating system of n-masses is self-locking to the
synchronized frequency of its subchains.",1006.1722v1
2010-08-20,First principles quasiparticle damping rates in bulk lead,"First principles calculations of the damping rates (inverse inelastic
lifetimes) of low energy quasiparticles in bulk Pb are presented. Damping rates
are obtained both for excited electrons and holes with energies up to 8 eV on a
set of k vectors throughout the Brillouin zone (BZ). Strong localization
effects in the calculated lifetimes are found. Averaged over the BZ inelastic
lifetimes versus quasiparticle energy are reported as well. In addition, the
effect of the spin-orbit induced splitting in the band structure on the
calculated lifetimes in Pb is investigated.",1008.3415v1
2010-12-07,Turbulence damping as a measure of the flow dimensionality,"The dimensionality of turbulence in fluid layers determines their properties.
We study electromagnetically driven flows in finite depth fluid layers and show
that eddy viscosity, which appears as a result of three-dimensional motions,
leads to increased bottom damping. The anomaly coefficient, which characterizes
the deviation of damping from the one derived using a quasi-two-dimensional
model, can be used as a measure of the flow dimensionality. Experiments in
turbulent layers show that when the anomaly coefficient becomes high, the
turbulent inverse energy cascade is suppressed. In the opposite limit
turbulence can self-organize into a coherent flow.",1012.1371v1
2011-03-18,Single File Diffusion of particles with long ranged interactions: damping and finite size effects,"We study the Single File Diffusion (SFD) of a cyclic chain of particles that
cannot cross each other, in a thermal bath, with long ranged interactions, and
arbitrary damping. We present simulations that exhibit new behaviors
specifically associated to systems of small number of particles and to small
damping. In order to understand those results, we present an original analysis
based on the decomposition of the particles motion in the normal modes of the
chain. Our model explains all dynamic regimes observed in our simulations, and
provides convincing estimates of the crossover times between those regimes.",1103.3642v1
2011-04-21,Spin Damping Monopole,"We present theoretical evidence that a magnetic monopole emerges in dynamic
magnetic systems in the presence of the spin-orbit interaction. The monopole
field is expressed in terms of spin damping associated with magnetization
dynamics. We demonstrate that the observation of this spin damping monopole is
accomplished electrically using Ampere's law for monopole current. Our
discovery suggests the integration of monopoles into electronics, namely,
monopolotronics.",1104.4215v2
2011-05-20,"Magnetization Dissipation in the Ferromagnetic Semiconductor (Ga,Mn)As","We compute the Gilbert damping in (Ga,Mn)As based on the scattering theory of
magnetization relaxation. The disorder scattering is included
non-perturbatively. In the clean limit, the spin-pumping from the localized
d-electrons to the itinerant holes dominates the relaxation processes. In the
diffusive regime, the breathing Fermi-surface effect is balanced by the effects
of interband scattering, which cause the Gilbert damping constant to saturate
at around 0.005. In small samples, the system shape induces a large anisotropy
in the Gilbert damping.",1105.4148v2
2011-08-16,Long time dynamics for forced and weakly damped KdV on the torus,"The forced and weakly damped Korteweg-de Vries (KdV) equation with periodic
boundary conditions is considered. Starting from $L^2$ and mean-zero initial
data we prove that the solution decomposes into two parts; a linear one which
decays to zero as time goes to infinity and a nonlinear one which always
belongs to a smoother space. As a corollary we prove that all solutions are
attracted by a ball in $H^s$, $s\in(0,1)$, whose radius depends only on $s$,
the $L^2$ norm of the forcing term and the damping parameter. This gives a new
proof for the existence of a smooth global attractor and provides quantitative
information on the size of the attractor set in $H^s$.",1108.3358v1
2011-10-12,Acceleration Control in Nonlinear Vibrating Systems based on Damped Least Squares,"A discrete time control algorithm using the damped least squares is
introduced for acceleration and energy exchange controls in nonlinear vibrating
systems. It is shown that the damping constant of least squares and sampling
time step of the controller must be inversely related to insure that vanishing
the time step has little effect on the results. The algorithm is illustrated on
two linearly coupled Duffing oscillators near the 1:1 internal resonance. In
particular, it is shown that varying the dissipation ratio of one of the two
oscillators can significantly suppress the nonlinear beat phenomenon.",1110.2811v2
2011-10-17,Normal Mode Expansion of Damped Coupled Oscillators in 3 dimensions,"In this paper, I aim to study free oscillations of a system of oscillators in
more than one dimensions in the absence of damping. The basic approach lies in
decoupling the motion in the individual perpendicular directions. Once the
equations are decoupled, the existent techniques of Normal mode expansion for
1-dimensional oscillators are used to solve for the equations of motion. I also
study the motion of a driven system of oscillators in higher dimensions in the
presence of a velocity dependent damping force.",1110.3773v1
2011-10-25,Distinguishing mesoscopic quantum superpositions from statistical mixtures in periodically shaken double wells,"For Bose-Einstein condensates in double wells, N-particle Rabi-like
oscillations often seem to be damped. Far from being a decoherence effect, the
apparent damping can indicate the emergence of quantum superpositions in the
many-particle quantum dynamics. However, in an experiment it would be difficult
to distinguish the apparent damping from decoherence effects. The present paper
suggests using controlled periodic shaking to quasi-instantaneously switch the
sign of an effective Hamiltonian, thus implementing an `echo' technique which
distinguishes quantum superpositions from statistical mixtures. The scheme for
the effective time-reversal is tested by numerically solving the time-dependent
N-particle Schrodinger equation.",1110.5444v1
2011-12-09,Perturbed damped pendulum: finding periodic solutions,"Using the damped pendulum system we introduce the averaging method to study
the periodic solutions of a dynamical system with small perturbation. We
provide sufficient conditions for the existence of periodic solutions with
small amplitude of the non--linear perturbed damped pendulum. The averaging
theory provides a useful means to study dynamical systems, accessible to Master
and PhD students.",1112.2129v2
2011-12-28,The role of damping for the driven anharmonic quantum oscillator,"For the model of a linearly driven quantum anharmonic oscillator, the role of
damping is investigated. We compare the position of the stable points in phase
space obtained from a classical analysis to the result of a quantum mechanical
analysis. The solution of the full master equation shows that the stable points
behave qualitatively similar to the classical solution but with small
modifications. Both the quantum effects and additional effects of temperature
can be described by renormalizing the damping.",1112.6119v1
2012-02-24,Small data global existence for the semilinear wave equation with space-time dependent damping,"In this paper we consider the critical exponent problem for the semilinear
wave equation with space-time dependent damping. When the damping is effective,
it is expected that the critical exponent agrees with that of only space
dependent coefficient case. We shall prove that there exists a unique global
solution for small data if the power of nonlinearity is larger than the
expected exponent. Moreover, we do not assume that the data are compactly
supported. However, it is still open whether there exists a blow-up solution if
the power of nonlinearity is smaller than the expected exponent.",1202.5379v1
2012-03-11,Magnetic damping of a carbon nanotube NEMS resonator,"A suspended, doubly clamped single wall carbon nanotube is characterized at
cryogenic temperatures. We observe specific switching effects in dc-current
spectroscopy of the embedded quantum dot. These have been identified previously
as nano-electromechanical self-excitation of the system, where positive
feedback from single electron tunneling drives mechanical motion. A magnetic
field suppresses this effect, by providing an additional damping mechanism.
This is modeled by eddy current damping, and confirmed by measuring the
resonance quality factor of the rf-driven nano-electromechanical resonator in
an increasing magnetic field.",1203.2319v2
2012-03-21,Approximate rogue wave solutions of the forced and damped Nonlinear Schrödinger equation for water waves,"We consider the effect of the wind and the dissipation on the nonlinear
stages of the modulational instability. By applying a suitable transformation,
we map the forced/damped Nonlinear Schr\""odinger (NLS) equation into the
standard NLS with constant coefficients. The transformation is valid as long as
|{\Gamma}t| \ll 1, with {\Gamma} the growth/damping rate of the waves due to
the wind/dissipation. Approximate rogue wave solutions of the equation are
presented and discussed. The results shed some lights on the effects of wind
and dissipation on the formation of rogue waves.",1203.4735v1
2012-07-24,Quantum capacity of an amplitude-damping channel with memory,"We calculate the quantum capacity of an amplitude-damping channel with time
correlated Markov noise, for two channel uses. Our results show that memory of
the channel increases it's ability to transmit quantum information
significantly. We analyze and compare our findings with earlier numerical
results on amplitude-damping channel with memory. An upper bound on the amount
of quantum information transmitted over the channel in presence of memory, for
an arbitrary number of channel uses is also presented.",1207.5612v3
2012-08-21,Protecting quantum entanglement from amplitude damping,"Quantum entanglement is a critical resource for quantum information and
quantum computation. However, entanglement of a quantum system is subjected to
change due to the interaction with the environment. One typical result of the
interaction is the amplitude damping that usually results in the reduction of
the entanglement. Here we propose a protocol to protect quantum entanglement
from the amplitude damping by applying Hadamard and CNOT gates. As opposed to
some recently studied methods, the scheme presented here does not require weak
measurement in the reversal process, leading to a faster recovery of
entanglement. We propose a possible experimental implementation based on linear
optical system.",1208.4187v2
2012-10-03,Exact solutions for discrete breathers in forced-damped chain,"Exact solutions for symmetric discrete breathers (DBs) are obtained in
forced-damped linear chain with on-site vibro-impact constraints. The damping
is related to inelastic impacts; the forcing may be chosen from broad class of
periodic antisymmetric functions. Global conditions for existence and stability
of the DB are established. Some unusual phenomena, like non-monotonous
dependence of the stability boundary on the forcing amplitude, are revealed
analytically for the full system and illustrated numerically for small periodic
lattices.",1210.1085v1
2012-12-18,Using the mobile phone acceleration sensor in Physics experiments: free and damped harmonic oscillations,"The mobile acceleration sensor has been used to in Physics experiments on
free and damped oscillations. Results for the period, frequency, spring
constant and damping constant match very well to measurements obtained by other
methods. The Accelerometer Monitor application for Android has been used to get
the outputs of the sensor. Perspectives for the Physics laboratory have also
been discussed.",1212.4403v1
2012-12-20,How long-range interactions tune the damping in compact stars,"Long-range interactions lead to non-Fermi liquid effects in dense matter. We
show that, in contrast to other material properties, their effect on the bulk
viscosity of quark matter is significant since they shift its resonant maximum
and can thereby change the viscosity by many orders of magnitude. This is of
importance for the damping of oscillations of compact stars, like in particular
unstable r-modes, and the quest to detect signatures of deconfined matter in
astrophysical observations. We find that, in contrast to neutron stars with
standard damping mechanisms, compact stars that contain ungapped quark matter
are consistent with the observed data on low mass x-ray binaries.",1212.5242v1
2013-02-12,Impact of gluon damping on heavy-quark quenching,"In this conference contribution, we discuss the influence of
gluon-bremsstrahlung damping in hot, absorptive QCD matter on the heavy-quark
radiation spectra. Within our Monte-Carlo implementation for the description of
the heavy-quark in-medium propagation we demonstrate that as a consequence of
gluon damping the quenching of heavy quarks becomes significantly affected at
higher transverse momenta.",1302.2934v1
2013-03-12,On nonlinear Schrodinger type equations with nonlinear damping,"We consider equations of nonlinear Schrodinger type augmented by nonlinear
damping terms. We show that nonlinear damping prevents finite time blow-up in
several situations, which we describe. We also prove that the presence of a
quadratic confinement in all spatial directions drives the solution of our
model to zero for large time. In the case without external potential we prove
that the solution may not go to zero for large time due to (non-trivial)
scattering.",1303.3033v2
2013-06-15,A formula for damping interarea oscillations with generator redispatch,"We derive a new formula for the sensitivity of electromechanical oscillation
damping with respect to generator redispatch. The formula could lead to some
combination of observations, computations and heuristics to more effectively
damp interarea oscillations.",1306.3590v2
2013-07-24,Eigenvalue asymptotics for the damped wave equation on metric graphs,"We consider the linear damped wave equation on finite metric graphs and
analyse its spectral properties with an emphasis on the asymptotic behaviour of
eigenvalues. In the case of equilateral graphs and standard coupling conditions
we show that there is only a finite number of high-frequency abscissas, whose
location is solely determined by the averages of the damping terms on each
edge. We further describe some of the possible behaviour when the edge lengths
are no longer necessarily equal but remain commensurate.",1307.6377v3
2013-10-14,Signatures of two-level defects in the temperature-dependent damping of nanomechanical silicon nitride resonators,"The damping rates of high quality factor nanomechanical resonators are well
beyond intrinsic limits. Here, we explore the underlying microscopic loss
mechanisms by investigating the temperature-dependent damping of the
fundamental and third harmonic transverse flexural mode of a doubly clamped
silicon nitride string. It exhibits characteristic maxima reminiscent of
two-level defects typical for amorphous materials. Coupling to those defects
relaxes the momentum selection rules, allowing energy transfer from discrete
long wavelength resonator modes to the high frequency phonon environment.",1310.3671v1
2013-10-25,Quenched decoherence in qubit dynamics due to strong amplitude-damping noise,"We study non-perturbatively the time evolution of a qubit subject to
amplitude-damping noise. We show that at strong coupling the qubit decoherence
can be quenched owing to large environment feedbacks, such that the qubit can
evolve coherently even in the long-time limit. As an application, we show that
for a quantum channel that consists of two independent qubits subject to
uncorrelated local amplitude-damping noises, it can maintain at strong coupling
finite entanglement and better than classical teleportation fidelity at long
times.",1310.6843v2
2013-11-16,Shear viscosity due to the Landau damping from quark-pion interaction,"We have calculated the shear viscosity coefficient $\eta$ of the strongly
interacting matter in the relaxation time approximation, where a quasi particle
description of quarks with its dynamical mass is considered from NJL model. Due
to the thermodynamic scattering of quarks with pseudo scalar type condensate
(i.e. pion), a non zero Landau damping will be acquired by the propagating
quarks. This Landau damping may be obtained from the Landau cut contribution of
the in-medium self-energy of quark-pion loop, which is evaluated in the
framework of real-time thermal field theory.",1311.4070v1
2013-12-19,Cyclotron dynamics of interacting bosons in artificial magnetic fields,"We study theoretically quantum dynamics of interacting bosons in artificial
magnetic fields as engineered in recent ultracold atomic experiments, where
quantum cyclotron orbital motion has been observed. With exact numerical
simulations and perturbative analyses, we find that interactions induce damping
in the cyclotron motion. The damping time is found to be dependent on
interaction and tunneling strengths monotonically, while its dependence on
magnetic flux is non-monotonic. Sufficiently strong interactions would render
bosons dynamically localized inhibiting the cyclotron motion. The damping
predicted by us can be construed as an interaction-induced quantum decoherence
of the cyclotron motion.",1312.5747v2
2014-01-11,Damping in two component Bose gas,"We investigate the Landau and Baliaev damping of the collective modes in a
two-component Bose gas using the mean-field approximation. We show that due to
the two body atom-atom interaction, oscillations of each component is coupled
to the thermal excitations of the other component which gives rise to creation
or destruction of the elementary excitations that can take place in the two
separate components.In addition we find that the damping is also enhanced due
to inter-component coupling.",1401.2537v1
2014-04-25,The time singular limit for a fourth-order damped wave equation for MEMS,"We consider a free boundary problem modeling electrostatic
microelectromechanical systems. The model consists of a fourth-order damped
wave equation for the elastic plate displacement which is coupled to an
elliptic equation for the electrostatic potential. We first review some recent
results on existence and non-existence of steady-states as well as on local and
global well-posedness of the dynamical problem, the main focus being on the
possible touchdown behavior of the elastic plate. We then investigate the
behavior of the solutions in the time singular limit when the ratio between
inertial and damping effects tends to zero.",1404.6342v1
2014-08-09,Local existence results for the Westervelt equation with nonlinear damping and Neumann as well as absorbing boundary conditions,"We investigate the Westervelt equation with several versions of nonlinear
damping and lower order damping terms and Neumann as well as absorbing boundary
conditions. We prove local in time existence of weak solutions under the
assumption that the initial and boundary data are sufficiently small.
Additionally, we prove local well-posedness in the case of spatially varying
$L^{\infty}$ coefficients, a model relevant in high intensity focused
ultrasound (HIFU) applications.",1408.2160v1
2014-08-11,Characterization and suppression techniques for degree of radiation damping in inversion recovery measurements,"Radiation damping (RD) has been shown to affect T1 measurement in inversion
recovery experiments. In this work, we demonstrate that the extent of RD
depends upon the T1 of the sample. RD difference spectroscopy (RADDSY) is used
to characterize the severity of RD, while gradient inversion recovery (GIR) is
used for RD suppression in T1 measurements. At 9.4 T, for the radiation damping
characteristic time (Trd) of 50 ms, these investigations show non-negligible RD
effects for T1 values greater than Trd, with severe distortions for T1 longer
than about 150 ms, showing reasonable agreement with the predicted Trd. We also
report a discrepancy between published expressions for the characteristic RD
time.",1408.2457v2
2014-09-28,Spin-electron acoustic waves: The Landau damping and ion contribution in the spectrum,"Separated spin-up and spin-down quantum kinetics is derived for more detailed
research of the spin-electron acoustic waves. Kinetic theory allows to obtain
spectrum of the spin-electron acoustic waves including effects of occupation of
quantum states more accurately than quantum hydrodynamics. We apply quantum
kinetic to calculate the Landau damping of the spin-electron acoustic waves. We
have considered contribution of ions dynamics in the spin-electron acoustic
wave spectrum. We obtain contribution of ions in the Landau damping in
temperature regime of classic ions. Kinetic analysis for ion-acoustic, zero
sound, and Langmuir waves at separated spin-up and spin-down electron dynamics
is presented as well.",1409.7885v1
2014-10-05,Ultimate limit of field confinement by surface plasmon polaritons,"We show that electric field confinement in surface plasmon polaritons
propagating at the metal/dielectric interfaces enhances the loss due to Landau
damping and which effectively limits the degree of confinement itself. We prove
that Landau damping and associated with it surface collision damping follow
directly from Lindhard formula for the dielectric constant of free electron gas
Furthermore, we demonstrate that even if all the conventional loss mechanisms,
caused by phonons, electron-electron, and interface roughness scattering, were
eliminated, the maximum attainable degree of confinement and the loss
accompanying it would not change significantly compared to the best existing
plasmonic materials, such as silver.",1410.1226v1
2014-10-15,Quasiparticle Damping of Surface Waves in Superfluid $^3$He and $^4$He,"Oscillations on free surface of superfluids at the inviscid limit are damped
by quasiparticle scattering. We have studied this effect in both superfluids
$^3$He and $^4$He deep below the respective critical temperatures. Surface
oscillators offer several benefits over immersed mechanical oscillators
traditionally used for similar purposes. Damping is modeled as specular
scattering of ballistic quasiparticles from the moving free surface. The model
is in reasonable agreement with our measurements for superfluid $^4$He but
significant deviation is found for $^3$He.",1410.4071v1
2014-12-22,Long time behavior for a semilinear hyperbolic equation with asymtotically vanishing damping term and convex potential,"We investigate the asymptotic behavior, as t goes to infinity, for a
semilinear hyperbolic equation with asymptotically smal dissipation and convex
potential. We prove that if the damping term behaves like K/t^\alpha for t
large enough, k>0 and 0</alpha<1 then every global solution converges weakly to
an equilibrium point. This result is a positive answer to a question left open
in the paper [A. Cabot and P. Frankel, Asymptotics for some semilinear
hyperbolic equation with non-autonomous damping. J. Differential Equations 252
(2012) 294-322.]",1412.7008v1
2015-02-06,Microscopic theory of Gilbert damping in metallic ferromagnets,"We present a microscopic theory for magnetization relaxation in metallic
ferromagnets of nanoscopic dimensions that is based on the dynamic spin
response matrix in the presence of spin-orbit coupling. Our approach allows the
calculation of the spin excitation damping rate even for perfectly crystalline
systems, where existing microscopic approaches fail. We demonstrate that the
relaxation properties are not completely determined by the transverse
susceptibility alone, and that the damping rate has a non-negligible frequency
dependence in experimentally relevant situations. Our results indicate that the
standard Landau-Lifshitz-Gilbert phenomenology is not always appropriate to
describe spin dynamics of metallic nanostructure in the presence of strong
spin-orbit coupling.",1502.02068v1
2015-03-03,Large Deviations for the Langevin equation with strong damping,"We study large deviations in the Langevin dynamics, with damping of order
$\e^{-1}$ and noise of order $1$, as $\e\downarrow 0$. The damping coefficient
is assumed to be state dependent. We proceed first with a change of time and
then, we use a weak convergence approach to large deviations and their
equivalent formulation in terms of the Laplace principle, to determine the good
action functional.
  Some applications of these results to the exit problem from a domain and to
the wave front propagation for a suitable class of reaction diffusion equations
are considered.",1503.01027v1
2015-03-14,Stabilization of the nonlinear damped wave equation via linear weak observability,"We consider the problem of energy decay rates for nonlinearly damped abstract
infinite dimensional systems. We prove sharp, simple and quasi-optimal energy
decay rates through an indirect method, namely a weak observability estimate
for the corresponding undamped system. One of the main advantage of these
results is that they allow to combine the optimal-weight convexity method of
Alabau-Boussouira and a methodology of Ammari-Tucsnak for weak stabilization by
observability. Our results extend to nonlinearly damped systems, those of
Ammari and Tucsnak. At the end, we give an appendix on the weak stabilization
of linear evolution systems.",1503.04356v1
2015-04-23,Magnetization damping in noncollinear spin valves with antiferromagnetic interlayer couplings,"We study the magnetic damping in the simplest of synthetic antiferromagnets,
i.e. antiferromagnetically exchange-coupled spin valves in which applied
magnetic fields tune the magnetic configuration to become noncollinear. We
formulate the dynamic exchange of spin currents in a noncollinear texture based
on the spindiffusion theory with quantum mechanical boundary conditions at the
ferrromagnet|normal-metal interfaces and derive the Landau-Lifshitz-Gilbert
equations coupled by the static interlayer non-local and the dynamic exchange
interactions. We predict non-collinearity-induced additional damping that can
be sensitively modulated by an applied magnetic field. The theoretical results
compare favorably with published experiments.",1504.06042v1
2015-06-02,"On the the wave equation with hyperbolic dynamical boundary conditions, interior and boundary damping and source","The aim of the paper is to study local Hadamard well-posedness for wave
equation with an hyperbolic dynamical boundary condition, internal and/or
boundary damping and sources for initial data in the natural energy space.
Moreover the regularity of solutions is studied. Finally a dynamical system is
generated when sources are at most linear at infinity, or they are dominated by
the damping terms.",1506.00910v4
2015-06-15,Tautochrone in the damped cycloidal pendulum,"The tautochrone on a cycloid curve is usually considered without drag force.
In this work, we investigate the motion of a damped cycloidal pendulum under
presence of a drag force. Using the Lagrange formulation, and considering
linear dependence with velocity for damping force, we found the dynamics of the
system to remain tautochrone. This dictates the possibility for studying the
tautochrone experimentally, e.g. the cycloidal pendulum in water or oil.",1506.04943v2
2015-07-04,Comments on turbulence theory by Qian and by Edwards and McComb,"We reexamine Liouville equation based turbulence theories proposed by Qian
{[}Phys. Fluids \textbf{26}, 2098 (1983){]} and Edwards and McComb {[}J. Phys.
A: Math. Gen. \textbf{2}, 157 (1969){]}, which are compatible with Kolmogorov
spectrum. These theories obtained identical equation for spectral density
$q(k)$ and different results for damping coefficient. Qian proposed variational
approach and Edwards and McComb proposed maximal entropy principle to obtain
equation for the damping coefficient. We show that assumptions used in these
theories to obtain damping coefficient correspond to unphysical conditions.",1507.01124v1
2015-08-24,Scaling variables and asymptotic profiles for the semilinear damped wave equation with variable coefficients,"We study the asymptotic behavior of solutions for the semilinear damped wave
equation with variable coefficients. We prove that if the damping is effective,
and the nonlinearity and other lower order terms can be regarded as
perturbations, then the solution is approximated by the scaled Gaussian of the
corresponding linear parabolic problem. The proof is based on the scaling
variables and energy estimates.",1508.05778v3
2015-10-01,Impact of surface collisions on enhancement and quenching of the luminescence near the metal nanoparticles,"The fact that surface-induced damping rate of surface plasmon polaritons
(SPPs) in metal nanoparticles increases with the decrease of particle size is
well known. We show that this rate also increases with the degree of the mode
confinement, hence damping of the higher order nonradiative SPP modes in
spherical particles is greatly enhanced relative to damping of the fundamental
(dipole) SPP mode. Since higher order modes are the ones responsible for
quenching of luminescence in the vicinity of metal surfaces, the degree of
quenching increases resulting in a substantial decrease in the amount of
attainable enhancement of the luminescence",1510.00321v1
2015-10-22,On numerical Landau damping for splitting methods applied to the Vlasov-HMF model,"We consider time discretizations of the Vlasov-HMF (Hamiltonian Mean-Field)
equation based on splitting methods between the linear and non-linear parts. We
consider solutions starting in a small Sobolev neighborhood of a spatially
homogeneous state satisfying a linearized stability criterion (Penrose
criterion). We prove that the numerical solutions exhibit a scattering behavior
to a modified state, which implies a nonlinear Landau damping effect with
polynomial rate of damping. Moreover, we prove that the modified state is close
to the continuous one and provide error estimates with respect to the time
stepsize.",1510.06555v1
2015-11-02,Asymptotic decomposition for nonlinear damped Klein-Gordon equations,"In this paper, we proved that if the solution to damped focusing Klein-Gordon
equations is global forward in time, then it will decouple into a finite number
of equilibrium points with different shifts from the origin. The core
ingredient of our proof is the existence of the ""concentration-compact
attractor"" which yields a finite number of profiles. Using damping effect, we
can prove all the profiles are equilibrium points.",1511.00437v3
2015-11-11,Contact Stiffness and Damping of Liquid Films in Dynamic Atomic Force Microscopy,"Small-amplitude dynamic atomic force microscopy (dynamic-AFM) in a simple
nonpolar liquid was studied through molecular dynamics simulations. We find
that within linear dynamics regime, the contact stiffness and damping of the
confined film exhibit the similar solvation force oscillations, and they are
generally out-of-phase. For the solidified film with integer monolayer
thickness, further compression of the film before layering transition leads to
higher stiffness and lower damping. We find that molecular diffusion in the
solidified film was nevertheless enhanced due to the mechanical excitation of
AFM tip.",1511.03580v1
2015-11-13,Nonlinear Radiation Damping of Nuclear Spin Waves and Magnetoelastic Waves in Antiferromagnets,"Parallel pumping of nuclear spin waves in antiferromagnetic CsMnF3 at liquid
helium temperatures and magnetoelastic waves in antiferromagnetic FeBO3 at
liquid nitrogen temperature in a helical resonator was studied. It was found
that the absorbed microwave power is approximately equal to the irradiated
power from the sample and that the main restriction mechanism of absortption in
both cases is defined by the nonlinear radiation damping predicted about two
decades ago. We believe that the nonlinear radiation damping is a common
feature of parallel pumping technique of all normal magnetic excitations and it
can be detected by purposeful experiments.",1511.04396v1
2016-03-01,Damped vacuum states of light,"We consider one-dimensional propagation of quantum light in the presence of a
block of material, with a full account of dispersion and absorption. The
electromagnetic zero-point energy for some frequencies is damped (suppressed)
by the block below the free-space value, while for other frequencies it is
increased. We also calculate the regularized (Casimir) zero-point energy at
each frequency and find that it too is damped below the free-space value (zero)
for some frequencies. The total Casimir energy is positive.",1603.00233v2
2016-04-18,Parameter Estimation of Gaussian-Damped Sinusoids from a Geometric Perspective,"The five parameter gaussian damped sinusoid equation is a reasonable model
for betatron motion with chromatic decoherence of the proton bunch centroid
signal in the ring at the Spallation Neutron Source. A geometric method for
efficiently fitting this equation to the turn by turn signals to extract the
betatron tune and damping constant will be presented. This method separates the
parameters into global and local parameters and allows the use of vector
arithmetic to eliminate the local parameters from the parameter search space.
Furthermore, this method is easily generalized to reduce the parameter search
space for a larger class of problems.",1604.05167v1
2016-04-20,Landau damping in finite regularity for unconfined systems with screened interactions,"We prove Landau damping for the collisionless Vlasov equation with a class of
$L^1$ interaction potentials (including the physical case of screened Coulomb
interactions) on $\mathbb R^3_x \times \mathbb R^3_v$ for localized
disturbances of an infinite, homogeneous background. Unlike the confined case
$\mathbb T^3_x \times \mathbb R_v^3$, results are obtained for initial data in
Sobolev spaces (as well as Gevrey and analytic classes). For spatial
frequencies bounded away from zero, the Landau damping of the density is
similar to the confined case. The finite regularity is possible due to an
additional dispersive mechanism available on $\mathbb R_x^3$ which reduces the
strength of the plasma echo resonance.",1604.05783v1
2016-04-26,Trigonometric Splines for Oscillator Simulation,"We investigate the effects of numerical damping for oscillator simulation
with spline methods. Numerical damping results in an artificial loss of energy
and leads therefore to unreliable results in the simulation of autonomous
systems, as e.g.\ oscillators. We show that the negative effects of numerical
damping can be eliminated by the use of trigonometric splines. This will be in
particular important for spline based adaptive methods.",1604.07607v1
2016-07-13,Optimal decay rate for the wave equation on a square with constant damping on a strip,"We consider the damped wave equation with Dirichlet boundary conditions on
the unit square. We assume the damping to be a characteristic function of a
strip. We prove the exact $t^{-4/3}$-decay rate for the energy of classical
solutions. This answers a question of Anantharaman and L\'eautaud (2014).",1607.03633v2
2016-09-05,Estimates of lifespan and blow-up rates for the wave equation with a time-dependent damping and a power-type nonlinearity,"We study blow-up behavior of solutions for the Cauchy problem of the
semilinear wave equation with time-dependent damping. When the damping is
effective, and the nonlinearity is subcritical, we show the blow-up rates and
the sharp lifespan estimates of solutions. Upper estimates are proved by an ODE
argument, and lower estimates are given by a method of scaling variables.",1609.01035v2
2016-09-06,Numerical Convergence Rate for a Diffusive Limit of Hyperbolic Systems: p-System with Damping,"This paper deals with diffusive limit of the p-system with damping and its
approximation by an Asymptotic Preserving (AP) Finite Volume scheme. Provided
the system is endowed with an entropy-entropy flux pair, we give the
convergence rate of classical solutions of the p-system with damping towards
the smooth solutions of the porous media equation using a relative entropy
method. Adopting a semi-discrete scheme, we establish that the convergence rate
is preserved by the approximated solutions. Several numerical experiments
illustrate the relevance of this result.",1609.01436v1
2016-09-20,Global existence and asymptotic behavior of solutions to the Euler equations with time-dependent damping,"We study the isentropic Euler equations with time-dependent damping, given by
$\frac{\mu}{(1+t)^\lambda}\rho u$. Here, $\lambda,\mu$ are two non-negative
constants to describe the decay rate of damping with respect to time. We will
investigate the global existence and asymptotic behavior of small data
solutions to the Euler equations when $0<\lambda<1,0<\mu$ in multi-dimensions
$n\geq 1$. The asymptotic behavior will coincide with the one that obtained by
many authors in the case $\lambda=0$. We will also show that the solution can
only decay polynomially in time while in the three dimensions, the vorticity
will decay exponentially fast.",1609.06286v1
2017-03-14,Landau damping in the multiscale Vlasov theory,"Vlasov kinetic theory is extended by adopting an extra one particle
distribution function as an additional state variable characterizing the
micro-turbulence internal structure. The extended Vlasov equation keeps the
reversibility, the Hamiltonian structure, and the entropy conservation of the
original Vlasov equation. In the setting of the extended Vlasov theory we then
argue that the Fokker-Planck type damping in the velocity dependence of the
extra distribution function induces the Landau damping. The same type of
extension is made also in the setting of fluid mechanics.",1703.04577v2
2017-03-15,Energy decay and diffusion phenomenon for the asymptotically periodic damped wave equation,"We prove local and global energy decay for the asymptotically periodic damped
wave equation on the Euclidean space. Since the behavior of high frequencies is
already mostly understood, this paper is mainly about the contribution of low
frequencies. We show in particular that the damped wave behaves like a solution
of a heat equation which depends on the H-limit of the metric and the mean
value of the absorption index.",1703.05112v1
2017-08-27,Global well-posedness for the semilinear wave equation with time dependent damping in the overdamping case,"We study global existence of solutions to the Cauchy problem for the wave
equation with time-dependent damping and a power nonlinearity in the
overdamping case. We prove the global well-posedness for small data in the
energy space for the whole energy-subcritical case. This result implies that
small data blow-up does not occur in the overdamping case, different from the
other cases, i.e. effective or non-effective damping.",1708.08044v2
2018-04-19,Damping of magnetization dynamics by phonon pumping,"We theoretically investigate pumping of phonons by the dynamics of a magnetic
film into a non-magnetic contact. The enhanced damping due to the loss of
energy and angular momentum shows interference patterns as a function of
resonance frequency and magnetic film thickness that cannot be described by
viscous (""Gilbert"") damping. The phonon pumping depends on magnetization
direction as well as geometrical and material parameters and is observable,
e.g., in thin films of yttrium iron garnet on a thick dielectric substrate.",1804.07080v2
2019-05-20,Stabilization of two strongly coupled hyperbolic equations in exterior domains,"In this paper we study the behavior of the total energy and the $L^2$-norm of
solutions of two coupled hyperbolic equations by velocities in exterior
domains. Only one of the two equations is directly damped by a localized
damping term. We show that, when the damping set contains the coupling one and
the coupling term is effective at infinity and on captive region, then the
total energy decays uniformly and the $L^2$-norm of smooth solutions is
bounded. In the case of two Klein-Gordon equations with equal speeds we deduce
an exponential decay of the energy.",1905.08370v1
2020-07-05,Oscillation of damped second order quasilinear wave equations with mixed arguments,"Following the previous work [1], we investigate the impact of damping on the
oscillation of smooth solutions to some kind of quasilinear wave equations with
Robin and Dirichlet boundary condition. By using generalized Riccati
transformation and technical inequality method, we give some sufficient
conditions to guarantee the oscillation of all smooth solutions. From the
results, we conclude that positive damping can ``hold back"" oscillation. At
last, some examples are presented to confirm our main results.",2007.02284v1
2020-07-08,A competition on blow-up for semilinear wave equations with scale-invariant damping and nonlinear memory term,"In this paper, we investigate blow-up of solutions to semilinear wave
equations with scale-invariant damping and nonlinear memory term in
$\mathbb{R}^n$, which can be represented by the Riemann-Liouville fractional
integral of order $1-\gamma$ with $\gamma\in(0,1)$. Our main interest is to
study mixed influence from damping term and the memory kernel on blow-up
conditions for the power of nonlinearity, by using test function method or
generalized Kato's type lemma. We find a new competition, particularly for the
small value of $\gamma$, on the blow-up range between the effective case and
the non-effective case.",2007.03954v2
2010-05-20,Nonclassical phase-space trajectories for the damped harmonic quantum oscillator,"The phase-space path-integral approach to the damped harmonic oscillator is
analyzed beyond the Markovian approximation. It is found that pairs of
nonclassical trajectories contribute to the path-integral representation of the
Wigner propagating function. Due to the linearity of the problem, the sum
coordinate of a pair still satisfies the classical equation of motion.
Furthermore, it is shown that the broadening of the Wigner propagating function
of the damped oscillator arises due to the time-nonlocal interaction mediated
by the heat bath.",1005.3839v1
2013-08-03,Hadamard well-posedness for a hyperbolic equation of viscoelasticity with supercritical sources and damping,"Presented here is a study of a viscoelastic wave equation with supercritical
source and damping terms. We employ the theory of monotone operators and
nonlinear semigroups, combined with energy methods to establish the existence
of a unique local weak solution. In addition, it is shown that the solution
depends continuously on the initial data and is global provided the damping
dominates the source in an appropriate sense.",1308.0720v2
2014-03-24,Existence Results for Some Damped Second-Order Volterra Integro-Differential Equations,"In this paper we make a subtle use of operator theory techniques and the
well-known Schauder fixed-point principle to establish the existence of
pseudo-almost automorphic solutions to some second-order damped
integro-differential equations with pseudo-almost automorphic coefficients. In
order to illustrate our main results, we will study the existence of
pseudo-almost automorphic solutions to a structurally damped plate-like
boundary value problem.",1403.5955v1
2016-11-08,Emulated Inertia and Damping of Converter-Interfaced Power Source,"Converter-interfaced power sources (CIPSs), like wind turbine and energy
storage, can be switched to the inertia emulation mode when the detected
frequency deviation exceeds a pre-designed threshold, i.e. dead band, to
support the frequency response of a power grid. This letter proposes an
approach to derive the emulated inertia and damping from a CIPS based on the
linearized model of the CIPS and the power grid, where the grid is represented
by an equivalent single machine. The emulated inertia and damping can be
explicitly expressed in time and turn out to be time-dependent.",1611.02698v1
2017-04-03,Linear inviscid damping and vorticity depletion for shear flows,"In this paper, we prove the linear damping for the 2-D Euler equations around
a class of shear flows under the assumption that the linearized operator has no
embedding eigenvalues. For the symmetric flows, we obtain the explicit decay
estimates of the velocity, which is the same as one for monotone shear flows.
We confirm a new dynamical phenomena found by Bouchet and Morita: the depletion
of the vorticity at the stationary streamlines, which could be viewed as a new
mechanism leading to the damping for the base flows with stationary
streamlines.",1704.00428v1
2017-04-25,Diffusion phenomena for the wave equation with space-dependent damping term growing at infinity,"In this paper, we study the asymptotic behavior of solutions to the wave
equation with damping depending on the space variable and growing at the
spatial infinity. We prove that the solution is approximated by that of the
corresponding heat equation as time tends to infinity. The proof is based on
semigroup estimates for the corresponding heat equation and weighted energy
estimates for the damped wave equation. To construct a suitable weight function
for the energy estimates, we study a certain elliptic problem.",1704.07650v1
2018-05-03,"Exact Intrinsic Localized Excitation of an Anisotropic Ferromagnetic Spin Chain in External Magnetic Field with Gilbert Damping, Spin Current and PT-Symmetry","We obtain the exact one-spin intrinsic localized excitation in an anisotropic
Heisenberg ferromagnetic spin chain in a constant/variable external magnetic
field with Gilbert damping included. We also point out how an appropriate
magnitude spin current term in a spin transfer nano-oscillator (STNO) can
stabilize the tendency towards damping. Further, we show how this excitation
can be sustained in a recently suggested PT-symmetric magnetic nanostructure.
We also briefly consider more general spin excitations.",1805.01230v1
2018-05-29,Asymptotic profile of solutions for strongly damped Klein-Gordon equations,"We consider the Cauchy problem in the whole space for strongly damped
Klein-Gordon equations. We derive asymptotic profles of solutions with weighted
initial data by a simple method introduced by R. Ikehata. The obtained results
show that the wave effect will be weak because of the mass term, especially in
the low dimensional case (n = 1,2) as compared with the strongly damped wave
equations without mass term (m = 0), so the most interesting topic in this
paper is the n = 1,2 cases.",1805.11975v1
2008-07-23,Tunneling-induced damping of phase coherence revivals in deep optical lattices,"We consider phase coherence collapse and revival in deep optical lattices,
and calculate within the Bose-Hubbard model the revival amplitude damping
incurred by a finite tunneling coupling of the lattice wells (after sweeping
from the superfluid to the Mott phase). Deriving scaling laws for the
corresponding decay of first-order coherence revival in terms of filling
factor, final lattice depth, and number of tunneling coupling partners, we
estimate whether revival-damping related to tunneling between sites can be or
even has already been observed in experiment.",0807.3627v2
2008-07-31,Generalized Theory of Landau Damping,"Collisionless damping of electrical waves in plasma is investigated in the
frame of the classical formulation of the problem. The new principle of
regularization of the singular integral is used. The exact solution of the
corresponding dispersion equation is obtained. The results of calculations lead
to existence of discrete spectrum of frequencies and discrete spectrum of
dispersion curves. Analytical results are in good coincidence with results of
direct mathematical experiments. Key words: Foundations of the theory of
transport processes and statistical physics; Boltzmann physical kinetics;
damping of plasma waves, linear theory of wave`s propagation PACS: 67.55.Fa,
67.55.Hc",0807.5007v1
2008-07-31,Scattering Theory of Gilbert Damping,"The magnetization dynamics of a single domain ferromagnet in contact with a
thermal bath is studied by scattering theory. We recover the
Landau-Liftshitz-Gilbert equation and express the effective fields and Gilbert
damping tensor in terms of the scattering matrix. Dissipation of magnetic
energy equals energy current pumped out of the system by the time-dependent
magnetization, with separable spin-relaxation induced bulk and spin-pumping
generated interface contributions. In linear response, our scattering theory
for the Gilbert damping tensor is equivalent with the Kubo formalism.",0807.5009v1
2009-12-16,Toward a dynamical shift condition for unequal mass black hole binary simulations,"Moving puncture simulations of black hole binaries rely on a specific gauge
choice that leads to approximately stationary coordinates near each black hole.
Part of the shift condition is a damping parameter, which has to be properly
chosen for stable evolutions. However, a constant damping parameter does not
account for the difference in mass in unequal mass binaries. We introduce a
position dependent shift damping that addresses this problem. Although the
coordinates change, the changes in the extracted gravitational waves are small.",0912.3125v1
2011-11-04,Tunable magnetization relaxation in spin valves,"In spin values the damping parameters of the free layer are determined
non-locally by the entire magnetic configuration. In a dual spin valve
structure that comprises a free layer embedded between two pinned layers, the
spin pumping mechanism, in combination with the angular momentum conservation,
renders the tensor-like damping parameters tunable by varying the interfacial
and diffusive properties. Simulations based on the Landau-Lifshitz-Gilbert
phenomenology for a macrospin model are performed with the tensor-like damping
and the relaxation time of the free layer magnetization is found to be largely
dependent on while tunable through the magnetic configuration of the
source-drain magnetization.",1111.1219v1
2011-11-23,Wave Propagation And Landau-Type Damping In Liquids,"Intermolecular forces are modeled by means of a modified Lennard-Jones
potential, introducing a distance of minimum approach, and the effect of
intermolecular interactions is accounted for with a self consistent field of
the Vlasov type. A Vlasov equation is then written and used to investigate the
propagation of perturbations in a liquid. A dispersion relation is obtained and
an effect of damping, analogous to what is known in plasmas as ""Landau
damping"", is found to take place.",1111.5519v3
2011-11-25,Radiation Damping for Speeding-up NMR Applications,"We demonstrate theoretically and numerically how to control the NMR
relaxation rate after application of the standard spin echo technique. Using
radiation damping, we return the nuclear magnetization to its equilibrium state
during a time interval that is negligible compared to the relaxation time. We
obtain an estimate for optimal radiation damping which is consistent with our
numerical simulations.",1111.7060v1
2012-01-03,Creating and studying ion acoustic waves in ultracold neutral plasmas,"We excite ion acoustic waves in ultracold neutral plasmas by imprinting
density modulations during plasma creation. Laser-induced fluorescence is used
to observe the density and velocity perturbations created by the waves. The
effect of expansion of the plasma on the evolution of the wave amplitude is
described by treating the wave action as an adiabatic invariant. After
accounting for this effect, we determine that the waves are weakly damped, but
the damping is significantly faster than expected for Landau damping.",1201.0786v1
2012-01-05,Damped bead on a rotating circular hoop - a bifurcation zoo,"The evergreen problem of a bead on a rotating hoop shows a multitude of
bifurcations when the bead moves with friction. This motion is studied for
different values of the damping coefficient and rotational speeds of the hoop.
Phase portraits and trajectories corresponding to all different modes of motion
of the bead are presented. They illustrate the rich dynamics associated with
this simple system. For some range of values of the damping coefficient and
rotational speeds of the hoop, linear stability analysis of the equilibrium
points is inadequate to classify their nature. A technique involving
transformation of coordinates and order of magnitude arguments is presented to
examine such cases. This may provide a general framework to investigate other
complex systems.",1201.1218v1
2012-04-02,Random Symmetry Breaking and Freezing in Chaotic Networks,"Parameter space of a driven damped oscillator in a double well potential
presents either a chaotic trajectory with sign oscillating amplitude or a
non-chaotic trajectory with a fixed sign amplitude. A network of such delay
coupled damped oscillators is shown to present chaotic dynamics while the
amplitude sign of each damped oscillator is randomly frozen. This phenomenon of
random broken global symmetry of the network simultaneously with random
freezing of each degree of freedom is accompanied by the existence of
exponentially many randomly frozen chaotic attractors with the ize of the
network. Results are exemplified by a network of modified Duffing oscillators
with infinite ange pseudo-inverse delayed interactions.",1204.0528v1
2012-04-04,Nonlinear Damping in Graphene Resonators,"Based on a continuum mechanical model for single-layer graphene we propose
and analyze a microscopic mechanism for dissipation in nanoelectromechanical
graphene resonators. We find that coupling between flexural modes and in-plane
phonons leads to linear and nonlinear damping of out-of-plane vibrations. By
tuning external parameters such as bias and ac voltages, one can cross over
from a linear to a nonlinear-damping dominated regime. We discuss the behavior
of the effective quality factor in this context.",1204.0911v2
2014-05-12,A note on a strongly damped wave equation with fast growing nonlinearities,"A strongly damped wave equation including the displacement depending
nonlinear damping term and nonlinear interaction function is considered. The
main aim of the note is to show that under the standard dissipativity
restrictions on the nonlinearities involved the initial boundary value problem
for the considered equation is globally well-posed in the class of sufficiently
regular solutions and the semigroup generated by the problem possesses a global
attractor in the corresponding phase space. These results are obtained for the
nonlinearities of an arbitrary polynomial growth and without the assumption
that the considered problem has a global Lyapunov function.",1405.2707v1
2014-06-03,Optimal Estimation of a Classical Force with a Damped Oscillator in the non-Markovian Bath,"We solve the optimal quantum limit of probing a classical force exactly by a
damped oscillator initially prepared in the factorized squeezed state. The
memory effects of the thermal bath on the oscillator evolution are
investigated. We show that the optimal force sensitivity obtained by the
quantum estimation theory approaches to zero for the non-Markovian bath,
whereas approaches to a finite non-zero value for the Markovian bath as the
energy of the damped oscillator goes to infinity.",1406.0658v1
2016-05-05,Theory of magnon motive force in chiral ferromagnets,"We predict that magnon motive force can lead to temperature dependent,
nonlinear chiral damping in both conducting and insulating ferromagnets. We
estimate that this damping can significantly influence the motion of skyrmions
and domain walls at finite temperatures. We also find that in systems with low
Gilbert damping moving chiral magnetic textures and resulting magnon motive
forces can induce large spin and energy currents in the transverse direction.",1605.01694v2
2016-08-29,"Stochastic 3D Navier-Stokes equations with nonlinear damping: martingale solution, strong solution and small time large deviation principles","In this paper, by using classical Faedo-Galerkin approximation and
compactness method, the existence of martingale solutions for the stochastic 3D
Navier-Stokes equations with nonlinear damping is obtained. The existence and
uniqueness of strong solution are proved for $\beta > 3$ with any $\alpha>0$
and $\alpha \geq \frac12$ as $\beta = 3$. Meanwhile, a small time large
deviation principle for the stochastic 3D Navier-Stokes equation with damping
is proved for $\beta > 3$ with any $\alpha>0$ and $\alpha \geq \frac12$ as
$\beta = 3$.",1608.07996v1
2016-12-09,Ornstein-Uhlenbeck Process with Fluctuating Damping,"This paper studies Langevin equation with random damping due to
multiplicative noise and its solution. Two types of multiplicative noise,
namely the dichotomous noise and fractional Gaussian noise are considered.
Their solutions are obtained explicitly, with the expressions of the mean and
covariance determined explicitly. Properties of the mean and covariance of the
Ornstein-Uhlenbeck process with random damping, in particular the asymptotic
behavior, are studied. The effect of the multiplicative noise on the stability
property of the resulting processes is investigated.",1612.03013v3
2016-12-20,Symmetry group classification and optimal reduction of a class of damped Timoshenko beam system with a nonlinear rotational moment,"We consider a nonlinear Timoshenko system of partial differential equations
(PDEs) with a frictional damping term in rotation angle. The nonlinearity is
due to the arbitrary dependence on the rotation moment. A Lie symmetry group
classification of the arbitrary function of rotation moment is presented. An
optimal system of one-dimensional subalgebras of the nonlinear damped
Timoshenko system is derived for all the non-linear cases. All possible
invariant variables of the optimal systems for the three non-linear cases are
presented. The corresponding reduced systems of ordinary differential equations
(ODEs) are also provided.",1612.06775v1
2017-06-05,Mixed finite elements for global tide models with nonlinear damping,"We study mixed finite element methods for the rotating shallow water
equations with linearized momentum terms but nonlinear drag. By means of an
equivalent second-order formulation, we prove long-time stability of the system
without energy accumulation. We also give rates of damping in unforced systems
and various continuous dependence results on initial conditions and forcing
terms. \emph{A priori} error estimates for the momentum and free surface
elevation are given in $L^2$ as well as for the time derivative and divergence
of the momentum. Numerical results confirm the theoretical results regarding
both energy damping and convergence rates.",1706.01352v1
2017-06-13,Uniform energy decay for wave equations with unbounded damping coefficients,"We consider the Cauchy problem for wave equations with unbounded damping
coefficients in the whole space. For a general class of unbounded damping
coefficients, we derive uniform total energy decay estimates together with a
unique existence result of a weak solution. In this case we never impose strong
assumptions such as compactness of the support of the initial data. This means
that we never rely on the finite propagation speed property of the solution,
and we try to deal with an essential unbounded coefficient case.",1706.03942v1
2017-06-15,Fractional Driven Damped Oscillator,"The resonances associated with a fractional damped oscillator which is driven
by an oscillatory external force are studied. It is shown that such resonances
can be manipulated by tuning up either the coefficient of the fractional
damping or the order of the corresponding fractional derivatives.",1706.08596v1
2017-07-11,Stability of partially locked states in the Kuramoto model through Landau damping with Sobolev regularity,"The Kuramoto model is a mean-field model for the synchronisation behaviour of
oscillators, which exhibits Landau damping. In a recent work, the nonlinear
stability of a class of spatially inhomogeneous stationary states was shown
under the assumption of analytic regularity. This paper proves the nonlinear
Landau damping under the assumption of Sobolev regularity. The weaker
regularity required the construction of a different more robust bootstrap
argument, which focuses on the nonlinear Volterra equation of the order
parameter.",1707.03475v2
2017-12-04,Graviton-mediated dark matter model explanation the DAMPE electron excess and search at $e^+e^-$ colliders,"The very recent result of the DAMPE cosmic ray spectrum of electrons shows a
narrow bump above the background at around 1.4 TeV. We attempt to explain the
DAMPE electron excess in a simplified Kaluza-Klein graviton-mediated dark
matter model, in which the graviton only interacts with leptons and dark
matter. The related phenomenological discussions are given and this simplified
graviton-mediated dark matter model has the potential to be cross-tested in
future lepton collider experiments.",1712.01143v1
2017-12-13,On nonlinear damped wave equations for positive operators. I. Discrete spectrum,"In this paper we study a Cauchy problem for the nonlinear damped wave
equations for a general positive operator with discrete spectrum. We derive the
exponential in time decay of solutions to the linear problem with decay rate
depending on the interplay between the bottom of the operator's spectrum and
the mass term. Consequently, we prove global in time well-posedness results for
semilinear and for more general nonlinear equations with small data. Examples
are given for nonlinear damped wave equations for the harmonic oscillator, for
the twisted Laplacian (Landau Hamiltonian), and for the Laplacians on compact
manifolds.",1712.05009v1
2018-09-10,Linear inviscid damping for the $β$-plane equation,"In this paper, we study the linear inviscid damping for the linearized
$\beta$-plane equation around shear flows. We develop a new method to give the
explicit decay rate of the velocity for a class of monotone shear flows. This
method is based on the space-time estimate and the vector field method in sprit
of the wave equation. For general shear flows including the Sinus flow, we also
prove the linear damping by establishing the limiting absorption principle,
which is based on the compactness method introduced by Wei-Zhang-Zhao in
\cite{WZZ2}. The main difficulty is that the Rayleigh-Kuo equation has more
singular points due to the Coriolis effects so that the compactness argument
becomes more involved and delicate.",1809.03065v1
2018-10-14,Critical exponent for nonlinear damped wave equations with non-negative potential in 3D,"We are studying possible interaction of damping coefficients in the
subprincipal part of the linear 3D wave equation and their impact on the
critical exponent of the corresponding nonlinear Cauchy problem with small
initial data. The main new phenomena is that certain relation between these
coefficients may cause very strong jump of the critical Strauss exponent in 3D
to the critical 5D Strauss exponent for the wave equation without damping
coefficients.",1810.05956v1
2018-10-23,Perfect absorption of water waves by linear or nonlinear critical coupling,"We report on experiments of perfect absorption for surface gravity waves
impinging a wall structured by a subwavelength resonator. By tuning the
geometry of the resonator, a balance is achieved between the radiation damping
and the intrinsic viscous damping, resulting in perfect absorption by critical
coupling. Besides, it is shown that the resistance of the resonator, hence the
intrinsic damping, can be controlled by the wave amplitude, which provides a
way for perfect absorption tuned by nonlinear mechanisms. The perfect absorber
that we propose, without moving parts or added material, is simple, robust and
it presents a deeply subwavelength ratio wavelength/size $\simeq 18$.",1810.09884v1
2019-06-02,Mixed control of vibrational systems,"We consider new performance measures for vibrational systems based on the
$H_2$ norm of linear time invariant systems. New measures will be used as an
optimization criterion for the optimal damping of vibrational systems. We
consider both theoretical and concrete cases in order to show how new measures
stack up against the standard measures. The quality and advantages of new
measures as well as the behaviour of optimal damping positions and
corresponding damping viscosities are illustrated in numerical experiments.",1906.00503v1
2019-06-27,Comments on the linear modified Poisson-Boltzmann equation in electrolyte solution theory,"Three analytic results are proposed for a linear form of the modified
Poisson-Boltzmann equation in the theory of bulk electrolytes. Comparison is
also made with the mean spherical approximation results. The linear theories
predict a transition of the mean electrostatic potential from a
Debye-H\""{u}ckel type damped exponential to a damped oscillatory behaviour as
the electrolyte concentration increases beyond a critical value. The screening
length decreases with increasing concentration when the mean electrostatic
potential is damped oscillatory. A comparison is made with one set of recent
experimental screening results for aqueous NaCl electrolytes.",1906.11584v1
2019-09-19,Growth rate and gain of stimulated Brillouin scattering considering nonlinear Landau damping due to particle trapping,"Growth rate and gain of SBS considering the reduced Landau damping due to
particle trapping has been proposed to predict the growth and average level of
SBS reflectivity. Due to particle trapping, the reduced Landau damping has been
taken used of to calculate the gain of SBS, which will make the simulation data
of SBS average reflectivity be consistent to the Tang model better. This work
will solve the pending questions in laser-plasma interaction and have wide
applications in parametric instabilities.",1909.11606v1
2020-01-17,Bounding the Classical Capacity of Multilevel Damping Quantum Channels,"A recent method to certify the classical capacity of quantum communication
channels is applied for general damping channels in finite dimension. The
method compares the mutual information obtained by coding on the computational
and a Fourier basis, which can be obtained by just two local measurement
settings and classical optimization. The results for large representative
classes of different damping structures are presented.",2001.06486v2
2020-01-27,Robustness of polynomial stability of damped wave equations,"In this paper we present new results on the preservation of polynomial
stability of damped wave equations under addition of perturbing terms. We in
particular introduce sufficient conditions for the stability of perturbed
two-dimensional wave equations on rectangular domains, a one-dimensional weakly
damped Webster's equation, and a wave equation with an acoustic boundary
condition. In the case of Webster's equation, we use our results to compute
explicit numerical bounds that guarantee the polynomial stability of the
perturbed equation.",2001.10033v3
2020-02-09,Fujita modified exponent for scale invariant damped semilinear wave equations,"The aim of this paper is to prove a blow up result of the solution for a
semilinear scale invariant damped wave equation under a suitable decay
condition on radial initial data. The admissible range for the power of the
nonlinear term depends both on the damping coefficient and on the pointwise
decay order of the initial data. In addition we give an upper bound estimate
for the lifespan of the solution, in terms of the power of the nonlinearity,
size and growth of initial data.",2002.03418v2
2020-02-16,Blow up results for semi-linear structural damped wave model with nonlinear memory,"This article is to study the nonexistence of global solutions to semi-linear
structurally damped wave equation with nonlinear memory in $\R^n$ for any space
dimensions $n\ge 1$ and for the initial arbitrarily small data being subject to
the positivity assumption. We intend to apply the method of a modified test
function to establish blow-up results and to overcome some difficulties as well
caused by the well-known fractional Laplacian $(-\Delta)^{\sigma/2}$ in
structural damping terms.",2002.06582v1
2020-04-22,Logarithmic stabilization of an acoustic system with a damping term of Brinkman type,"We study the problem of stabilization for the acoustic system with a
spatially distributed damping. Without imposing any hypotheses on the
structural properties of the damping term, we identify logarithmic decay of
solutions with growing time. Logarithmic decay rate is shown by using a
frequency domain method and combines a contradiction argument with the
multiplier technique and a new Carleman estimate to carry out a special
analysis for the resolvent.",2004.10669v1
2021-01-23,Oscillation time and damping coefficients in a nonlinear pendulum,"We establish a relationship between the normalized damping coefficients and
the time that takes a nonlinear pendulum to complete one oscillation starting
from an initial position with vanishing velocity. We establish some conditions
on the nonlinear restitution force so that this oscillation time does not
depend monotonically on the viscosity damping coefficient.",2101.09400v2
2012-05-22,Heavy quark damping rate in hot viscous QCD plasma,"We derive an expression for the heavy quark damping rate in hot quark gluon
plasma in presence of flow. Here all the bath particles here are out of
equilibrium due to the existence of non-zero velocity gradient. The magnetic
sector shows similar infrared divergences even after hard thermal loop
corrections as one encounters in case of non-viscous plasma. We estimate the
first order correction in ($\eta/s$) for heavy quark damping rate due to the
non-zero viscosity of the QCD plasma.",1205.4895v3
2012-05-25,Spin wave amplification driven by heat flow: the role of damping and exchange interaction,"In this article we report on micromagnetic simulations performed on a
permalloy nanostructure in presence of a uniform thermal gradient. Our
numerical simulations show that heat flow is an effective mean to compensate
the damping, and that the gradients at which spin-wave amplification is
observed are experimentally accessible. In particular, we have studied the role
of the Gilbert damping parameter on spin-wave amplification.",1205.5650v2
2017-09-04,A note on the blowup of scale invariant damping wave equation with sub-Strauss exponent,"We concern the blow up problem to the scale invariant damping wave equations
with sub-Strauss exponent. This problem has been studied by Lai, Takamura and
Wakasa (\cite{Lai17}) and Ikeda and Sobajima \cite{Ikedapre} recently. In
present paper, we extend the blowup exponent from $p_F(n)\leq p<p_S(n+2\mu)$ to
$1<p<p_S(n+\mu)$ without small restriction on $\mu$. Moreover, the upper bound
of lifespan is derived with uniform estimate $T(\varepsilon)\leq
C\varepsilon^{-2p(p-1)/\gamma(p,n+2\mu)}$. This result extends the blowup
result of semilinear wave equation and shows the wave-like behavior of scale
invariant damping wave equation's solution even with large $\mu>1$.",1709.00866v2
2017-09-13,Life-span of blowup solutions to semilinear wave equation with space-dependent critical damping,"This paper is concerned with the blowup phenomena for initial value problem
of semilinear wave equation with critical space-dependent damping term
(DW:$V$). The main result of the present paper is to give a solution of the
problem and to provide a sharp estimate for lifespan for such a solution when
$\frac{N}{N-1}<p\leq p_S(N+V_0)$, where $p_S(N)$ is the Strauss exponent for
(DW:$0$). The main idea of the proof is due to the technique of test functions
for (DW:$0$) originated by Zhou--Han (2014, MR3169791). Moreover, we find a new
threshold value $V_0=\frac{(N-1)^2}{N+1}$ for the coefficient of critical and
singular damping $|x|^{-1}$.",1709.04401v1
2017-09-24,Suppression of Recurrence in the Hermite-Spectral Method for Transport Equations,"We study the unphysical recurrence phenomenon arising in the numerical
simulation of the transport equations using Hermite-spectral method. From a
mathematical point of view, the suppression of this numerical artifact with
filters is theoretically analyzed for two types of transport equations. It is
rigorously proven that all the non-constant modes are damped exponentially by
the filters in both models, and formally shown that the filter does not affect
the damping rate of the electric energy in the linear Landau damping problem.
Numerical tests are performed to show the effect of the filters.",1709.08194v1
2017-11-01,Life-Span of Semilinear Wave Equations with Scale-invariant Damping: Critical Strauss Exponent Case,"The blow up problem of the semilinear scale-invariant damping wave equation
with critical Strauss type exponent is investigated. The life span is shown to
be: $T(\varepsilon)\leq C\exp(\varepsilon^{-2p(p-1)})$ when $p=p_S(n+\mu)$ for
$0<\mu<\frac{n^2+n+2}{n+2}$. This result completes our previous study
\cite{Tu-Lin} on the sub-Strauss type exponent $p<p_S(n+\mu)$. Our novelty is
to construct the suitable test function from the modified Bessel function. This
approach might be also applied to the other type damping wave equations.",1711.00223v1
2017-11-14,Spin-Noise and Damping in Individual Metallic Ferromagnetic Nanoparticles,"We introduce a highly sensitive and relatively simple technique to observe
magnetization motion in single Ni nanoparticles, based on charge sensing by
electron tunneling at millikelvin temperature. Sequential electron tunneling
via the nanoparticle drives nonequilibrium magnetization dynamics, which
induces an effective charge noise that we measure in real time. In the free
spin diffusion regime, where the electrons and magnetization are in detailed
balance, we observe that magnetic damping time exhibits a peak with the
magnetic field, with a record long damping time of $\simeq 10$~ms.",1711.05142v1
2018-03-14,Damped Newton's Method on Riemannian Manifolds,"A damped Newton's method to find a singularity of a vector field in
Riemannian setting is presented with global convergence study. It is ensured
that the sequence generated by the proposed method reduces to a sequence
generated by the Riemannian version of the classical Newton's method after a
finite number of iterations, consequently its convergence rate is
superlinear/quadratic. Moreover, numerical experiments illustrate that the
damped Newton's method has better performance than Newton's method in number of
iteration and computational time.",1803.05126v2
2018-06-08,"Brownian motion of magnetic domain walls and skyrmions, and their diffusion constants","Extended numerical simulations enable to ascertain the diffusive behavior at
finite temperatures of chiral walls and skyrmions in ultra-thin model Co layers
exhibiting symmetric - Heisenberg - as well as antisymmetric -
Dzyaloshinskii-Moriya - exchange interactions. The Brownian motion of walls and
skyrmions is shown to obey markedly different diffusion laws as a function of
the damping parameter. Topology related skyrmion diffusion suppression with
vanishing damping parameter, albeit already documented, is shown to be
restricted to ultra-small skyrmion sizes or, equivalently, to ultra-low damping
coefficients, possibly hampering observation.",1806.03172v1
2018-06-18,Damped second order flow applied to image denoising,"In this paper, we introduce a new image denoising model: the damped flow
(DF), which is a second order nonlinear evolution equation associated with a
class of energy functionals of image. The existence, uniqueness and
regularization property of DF are proven. For the numerical implementation,
based on the St\""{o}rmer-Verlet method, a discrete damped flow, SV-DDF, is
developed. The convergence of SV-DDF is studied as well. Several numerical
experiments, as well as a comparison with other methods, are provided to
demonstrate the feasibility and effectiveness of the SV-DDF.",1806.06732v2
2018-07-10,Cyclotron Damping along an Uniform Magnetic Field,"We prove cyclotron damping for the collisionless Vlasov-Maxwell equations on
$\mathbb{T}_{x}^{3}\times\mathbb{R}_{v}^{3}$ under the assumptions that the
electric induction is zero and $(\mathcal{\mathbf{PSC}})$ holds. It is a
crucial step to solve the stability problem of the Vlasov-Maxwell equations.
Our proof is based on a new dynamical system of the plasma particles,
originating from Faraday Law of Electromagnetic induction and Lenz's Law. On
the basis of it, we use the improved Newton iteration scheme to show the
damping mechanism.",1807.05254v3
2018-07-17,On the blow-up for critical semilinear wave equations with damping in the scattering case,"We consider the Cauchy problem for semilinear wave equations with variable
coefficients and time-dependent scattering damping in $\mathbf{R}^n$, where
$n\geq 2$. It is expected that the critical exponent will be Strauss' number
$p_0(n)$, which is also the one for semilinear wave equations without damping
terms. Lai and Takamura (2018) have obtained the blow-up part, together with
the upper bound of lifespan, in the sub-critical case $p<p_0(n)$. In this
paper, we extend their results to the critical case $p=p_0(n)$. The proof is
based on Wakasa and Yordanov (2018), which concerns the blow-up and upper bound
of lifespan for critical semilinear wave equations with variable coefficients.",1807.06164v1
2018-08-22,Radiation Damping of a Yang-Mills Particle Revisited,"The problem of a color-charged point particle interacting with a four
dimensional Yang-Mills gauge theory is revisited. The radiation damping is
obtained inspired in the Dirac's computation. The difficulties in the
non-abelian case were solved by using an ansatz for the Li\'enard-Wiechert
potentials, already used in the literature for finding solutions to the
Yang-Mills equations. Three non-trivial examples of radiation damping for the
non-abelian particle are discussed in detail.",1808.07533v2
2018-08-28,Enhancement of zonal flow damping due to resonant magnetic perturbations in the background of an equilibrium $E \times B$ sheared flow,"Using a parametric interaction formalism, we show that the equilibrium
sheared rotation can enhance the zonal flow damping effect found in Ref. [M.
Leconte and P.H. Diamond, \emph{Phys. Plasmas} 19, 055903 (2012)]. This
additional damping contribution is proportional to $(L_s/L_V)^2 \times \delta
B_r^2 / B^2$, where $L_s/L_V$ is the ratio of magnetic shear length to the
scale-length of equilibrium $E \times B$ flow shear, and $\delta B_r / B$ is
the amplitude of the external magnetic perturbation normalized to the
background magnetic field.",1808.09110v1
2018-08-30,Optimal indirect stability of a weakly damped elastic abstract system of second order equations coupled by velocities,"In this paper, by means of the Riesz basis approach, we study the stability
of a weakly damped system of two second order evolution equations coupled
through the velocities. If the fractional order damping becomes viscous and the
waves propagate with equal speeds, we prove exponential stability of the system
and, otherwise, we establish an optimal polynomial decay rate. Finally, we
provide some illustrative examples.",1808.10256v1
2018-12-16,Damping of sound waves by bulk viscosity in reacting gases,"The very long standing problem of sound waves propagation in fluids is
reexamined. In particular, from the analysis of the wave damping in reacting
gases following the work of Einsten \citep{Ein}, it is found that the damping
due to the chemical reactions occurs nonetheless the second (bulk) viscosity
introduced by Landau \& Lifshitz \citep{LL86} is zero. The simple but important
case of a recombining Hydrogen plasma is examined.",1812.06478v1
2019-02-27,Forward Discretely Self-Similar Solutions of the MHD Equations and the Viscoelastic Navier-Stokes Equations with Damping,"In this paper, we prove the existence of forward discretely self-similar
solutions to the MHD equations and the viscoelastic Navier-Stokes equations
with damping with large weak $L^3$ initial data. The same proving techniques
are also applied to construct self-similar solutions to the MHD equations and
the viscoelastic Navier-Stokes equations with damping with large weak $L^3$
initial data. This approach is based on [Z. Bradshaw and T.-P. Tsai, Ann. Henri
Poincar'{e}, vol. 18, no. 3, 1095-1119, 2017].",1902.10771v3
2019-03-11,The effect of magnetic twist on resonant absorption of slow sausage waves in magnetic flux tubes,"Observations show that twisted magnetic flux tubes are present throughout the
sun's atmosphere. The main aim of this work is to obtain the damping rate of
sausage modes in the presence of magnetic twist. Using the connection formulae
obtained by Sakurai et al. (1991), we investigate resonant absorption of the
sausage modes in the slow continuum under photosphere conditions. We derive the
dispersion relation and solve it numerically and consequently obtain the
frequencies and damping rates of the slow surface sausage modes. We conclude
that the magnetic twist can result in strong damping in comparison with the
untwisted case.",1903.04171v1
2019-03-14,Endpoint Strichartz estimate for the damped wave equation and its application,"Recently, the Strichartz estimates for the damped wave equation was obtained
by the first author except for the wave endpoint case. In the present paper, we
give the Strichartz estimate in the wave endpoint case. We slightly modify the
argument of Keel--Tao. Moreover, we apply the endpoint Strichartz estimate to
the unconditional uniqueness for the energy critical nonlinear damped wave
equation. This problem seems not to be solvable as the perturbation of the wave
equation.",1903.05891v2
2019-04-02,Linear inviscid damping in Gevrey spaces,"We prove linear inviscid damping near a general class of monotone shear flows
in a finite channel, in Gevrey spaces. It is an essential step towards proving
nonlinear inviscid damping for general shear flows that are not close to the
Couette flow, which is a major open problem in 2d Euler equations.",1904.01188v2
2019-04-16,Damping modes of harmonic oscillator in open quantum systems,"Through a set of generators that preserves the hermiticity and trace of
density matrices, we analyze the damping of harmonic oscillator in open quantum
systems into four modes, distinguished by their specific effects on the
covariance matrix of position and momentum of the oscillator. The damping modes
could either cause exponential decay to the initial covariance matrix or shift
its components. They have to act together properly in actual dynamics to ensure
that the generalized uncertainty relation is satisfied. We use a few quantum
master equations to illustrate the results.",1904.07452v2
2019-11-26,Pullback Attractors for a Critical Degenerate Wave Equation with Time-dependent Damping,"The aim of this paper is to analyze the long-time dynamical behavior of the
solution for a degenerate wave equation with time-dependent damping term
$\partial_{tt}u + \beta(t)\partial_tu = \mathcal{L}u(x,t) + f(u)$ on a bounded
domain $\Omega\subset\mathbb{R}^N$ with Dirichlet boundary conditions. Under
some restrictions on $\beta(t)$ and critical growth restrictions on the
nonlinear term $f$, we will prove the local and global well-posedness of the
solution and derive the existence of a pullback attractor for the process
associated with the degenerate damped hyperbolic problem.",1911.11432v1
2019-12-18,Blow-up criteria for linearly damped nonlinear Schrödinger equations,"We consider the Cauchy problem for linearly damped nonlinear Schr\""odinger
equations
  \[ i\partial_t u + \Delta u + i a u= \pm |u|^\alpha u, \quad (t,x) \in
[0,\infty) \times \mathbb{R}^N, \] where $a>0$ and $\alpha>0$. We prove the
global existence and scattering for a sufficiently large damping parameter in
the energy-critical case. We also prove the existence of finite time blow-up
$H^1$ solutions to the focusing problem in the mass-critical and
mass-supercritical cases.",1912.08752v2
2020-03-04,Existence and uniqueness of solutions to the damped Navier-Stokes equations with Navier boundary conditions for three dimensional incompressible fluid,"In this article, we study the solutions of the damped Navier--Stokes equation
with Navier boundary condition in a bounded domain $\Omega$ in $\mathbb{R}^3$
with smooth boundary. The existence of the solutions is global with the damped
term $\vartheta |u|^{\beta-1}u, \vartheta >0.$ The regularity and uniqueness of
solutions with Navier boundary condition is also studied. This extends the
existing results in literature.",2003.01903v1
2020-05-24,A transmission problem for the Timoshenko system with one local Kelvin-Voigt damping and non-smooth coefficient at the interface,"In this paper, we study the indirect stability of Timoshenko system with
local or global Kelvin-Voigt damping, under fully Dirichlet or mixed boundary
conditions. Unlike the results of H. L. Zhao, K. S. Liu, and C. G. Zhang and of
X. Tian and Q. Zhang, in this paper, we consider the Timoshenko system with
only one locally or globally distributed Kelvin-Voigt damping. Indeed, we prove
that the energy of the system decays polynomially and that the obtained decay
rate is in some sense optimal. The method is based on the frequency domain
approach combining with multiplier method.",2005.12756v1
2020-06-09,Lifespan of solutions to a damped fourth-order wave equation with logarithmic nonlinearity,"This paper is devoted to the lifespan of solutions to a damped fourth-order
wave equation with logarithmic nonlinearity $$u_{tt}+\Delta^2u-\Delta
u-\omega\Delta u_t+\alpha(t)u_t=|u|^{p-2}u\ln|u|.$$ Finite time blow-up
criteria for solutions at both lower and high initial energy levels are
established, and an upper bound for the blow-up time is given for each case.
Moreover, by constructing a new auxiliary functional and making full use of the
strong damping term, a lower bound for the blow-up time is also derived.",2006.05006v1
2020-08-02,Quantum capacity analysis of multi-level amplitude damping channels,"The set of Multi-level Amplitude Damping (MAD) quantum channels is introduced
as a generalization of the standard qubit Amplitude Damping Channel to quantum
systems of finite dimension $d$. In the special case of $d=3$, by exploiting
degradability, data-processing inequalities, and channel isomorphism, we
compute the associated quantum and private classical capacities for a rather
wide class of maps, extending the set of solvable models known so far. We
proceed then to the evaluation of the entanglement assisted, quantum and
classical, capacities.",2008.00477v3
2020-08-11,An inverse spectral problem for a damped wave operator,"This paper proposes a new and efficient numerical algorithm for recovering
the damping coefficient from the spectrum of a damped wave operator, which is a
classical Borg-Levinson inverse spectral problem. The algorithm is based on
inverting a sequence of trace formulas, which are deduced by a recursive
formula, bridging geometrical and spectrum information explicitly in terms of
Fredholm integral equations. Numerical examples are presented to illustrate the
efficiency of the proposed algorithm.",2008.04523v1
2020-08-17,Asymptotic profiles and singular limits for the viscoelastic damped wave equation with memory of type I,"In this paper, we are interested in the Cauchy problem for the viscoelastic
damped wave equation with memory of type I. By applying WKB analysis and
Fourier analysis, we explain the memory's influence on dissipative structures
and asymptotic profiles of solutions to the model with weighted $L^1$ initial
data. Furthermore, concerning standard energy and the solution itself, we
establish singular limit relations between the Moore-Gibson-Thompson equation
with memory and the viscoelastic damped wave equation with memory.",2008.07151v1
2020-08-18,A class of Finite difference Methods for solving inhomogeneous damped wave equations,"In this paper, a class of finite difference numerical techniques is presented
to solve the second-order linear inhomogeneous damped wave equation. The
consistency, stability, and convergences of these numerical schemes are
discussed. The results obtained are compared to the exact solution, ordinary
explicit, implicit finite difference methods, and the fourth-order compact
method (FOCM). The general idea of these methods is developed by using the
C0-semigroups operator theory. We also showed that the stability region for the
explicit finite difference scheme depends on the damping coefficient.",2008.08043v2
2020-09-10,Blow-up results for semilinear damped wave equations in Einstein-de Sitter spacetime,"We prove by using an iteration argument some blow-up results for a semilinear
damped wave equation in generalized Einstein-de Sitter spacetime with a
time-dependent coefficient for the damping term and power nonlinearity. Then,
we conjecture an expression for the critical exponent due to the main blow-up
results, which is consistent with many special cases of the considered model
and provides a natural generalization of Strauss exponent. In the critical
case, we consider a non-autonomous and parameter-dependent Cauchy problem for a
linear ODE of second-order, whose explicit solutions are determined by means of
special functions' theory.",2009.05372v1
2020-09-11,Asymptotic profiles for a wave equation with parameter dependent logarithmic damping,"We study a nonlocal wave equation with logarithmic damping which is rather
weak in the low frequency zone as compared with frequently studied strong
damping case. We consider the Cauchy problem for this model in the whole space
and we study the asymptotic profile and optimal estimates of the solutions and
the total energy as time goes to infinity in L^{2}-sense. In that case some
results on hypergeometric functions are useful.",2009.06395v1
2020-09-17,Sensitivity of steady states in a degenerately-damped stochastic Lorenz system,"We study stability of solutions for a randomly driven and degenerately damped
version of the Lorenz '63 model. Specifically, we prove that when damping is
absent in one of the temperature components, the system possesses a unique
invariant probability measure if and only if noise acts on the convection
variable. On the other hand, if there is a positive growth term on the vertical
temperature profile, we prove that there is no normalizable invariant state.
Our approach relies on the derivation and analysis of non-trivial Lyapunov
functions which ensure positive recurrence or null-recurrence/transience of the
dynamics.",2009.08429v1
2021-02-20,Lifespan estimates for semilinear wave equations with space dependent damping and potential,"In this work, we investigate the influence of general damping and potential
terms on the blow-up and lifespan estimates for energy solutions to power-type
semilinear wave equations. The space-dependent damping and potential functions
are assumed to be critical or short range, spherically symmetric perturbation.
The blow up results and the upper bound of lifespan estimates are obtained by
the so-called test function method. The key ingredient is to construct special
positive solutions to the linear dual problem with the desired asymptotic
behavior, which is reduced, in turn, to constructing solutions to certain
elliptic ""eigenvalue"" problems.",2102.10257v1
2021-02-24,Attractors for locally damped Bresse systems and a unique continuation property,"This paper is devoted to Bresse systems, a robust model for circular beams,
given by a set of three coupled wave equations. The main objective is to
establish the existence of global attractors for dynamics of semilinear
problems with localized damping. In order to deal with localized damping a
unique continuation property (UCP) is needed. Therefore we also provide a
suitable UCP for Bresse systems. Our strategy is to set the problem in a
Riemannian geometry framework and see the system as a single equation with
different Riemann metrics. Then we perform Carleman-type estimates to get our
result.",2102.12025v1
2021-03-09,Global weak solution of 3D-NSE with exponential damping,"In this paper we prove the global existence of incompressible Navier-Stokes
equations with damping $\alpha (e^{\beta |u|^2}-1)u$, where we use Friedrich
method and some new tools. The delicate problem in the construction of a global
solution, is the passage to the limit in exponential nonlinear term. To solve
this problem, we use a polynomial approximation of the damping part and a new
type of interpolation between $L^\infty(\mathbb{R}^+,L^2(\mathbb{R}^3))$ and
the space of functions $f$ such that $(e^{\beta|f|^2}-1)|f|^2\in
L^1(\mathbb{R}^3)$. Fourier analysis and standard techniques are used.",2103.05388v1
2021-05-03,Enhanced and unenhanced dampings of Kolmogorov flow,"In the present study, Kolmogorov flow represents the stationary sinusoidal
solution $(\sin y,0)$ to a two-dimensional spatially periodic Navier-Stokes
system, driven by an external force. This system admits the additional
non-stationary solution $(\sin y,0)+e^{-\nu t} (\sin y,0)$, which tends
exponentially to the Kolmogorov flow at the minimum decay rate determined by
the viscosity $\nu$. Enhanced damping or enhanced dissipation of the problem is
obtained by presenting higher decay rate for the difference between a solution
and the non-stationary basic solution. Moreover, for the understanding of the
metastability problem in an explicit manner, a variety of exact solutions are
presented to show enhanced and unenhanced dampings.",2105.00730v2
2021-05-06,On Linear Damping Around Inhomogeneous Stationary States of the Vlasov-HMF Model,"We study the dynamics of perturbations around an inhomogeneous stationary
state of the Vlasov-HMF (Hamiltonian Mean-Field) model, satisfying a linearized
stability criterion (Penrose criterion). We consider solutions of the
linearized equation around the steady state, and prove the algebraic decay in
time of the Fourier modes of their density. We prove moreover that these
solutions exhibit a scattering behavior to a modified state, implying a linear
Landau damping effect with an algebraic rate of damping.",2105.02484v1
2021-05-31,Blowup of Solutions to a Damped Euler Equation with Homogeneous Three-Point Boundary Condition,"It has been established that solutions to the inviscid Proudman-Johnson
equation subject to a homogeneous three-point boundary condition can develop
singularities in finite time. In this paper, we consider the possibility of
singularity formation in solutions of the generalized, inviscid
Proudman-Johnson equation with damping subject to the same homogeneous
three-point boundary condition. In particular, we derive conditions the initial
data must satisfy in order for solutions to blowup in finite time with either
bounded or unbounded smooth damping term.",2106.00068v1
2021-06-16,Sharp upper and lower bounds of the attractor dimension for 3D damped Euler-Bardina equations,"The dependence of the fractal dimension of global attractors for the damped
3D Euler--Bardina equations on the regularization parameter $\alpha>0$ and
Ekman damping coefficient $\gamma>0$ is studied. We present explicit upper
bounds for this dimension for the case of the whole space, periodic boundary
conditions, and the case of bounded domain with Dirichlet boundary conditions.
The sharpness of these estimates when $\alpha\to0$ and $\gamma\to0$ (which
corresponds in the limit to the classical Euler equations) is demonstrated on
the 3D Kolmogorov flows on a torus.",2106.09077v1
2021-06-23,Damping of the Franz-Keldysh oscillations in the presence of disorder,"Franz-Keldysh oscillations of the optical absorption in the presence of
short-range disorder are studied theoretically. The magnitude of the effect
depends on the relation between the mean-free path in a zero field and the
distance between the turning points in electric field. Damping of the
Franz-Keldysh oscillations by the disorder develops at high absorption
frequency. Effect of damping is amplified by the fact that, that electron and
hole are most sensitive to the disorder near the turning points. This is
because, near the turning points, velocities of electron and hole turn to zero.",2106.12691v1
2021-06-25,Perturbed primal-dual dynamics with damping and time scaling coefficients for affine constrained convex optimization problems,"In Hilbert space, we propose a family of primal-dual dynamical system for
affine constrained convex optimization problem. Several damping coefficients,
time scaling coefficients, and perturbation terms are thus considered. By
constructing the energy functions, we investigate the convergence rates with
different choices of the damping coefficients and time scaling coefficients.
Our results extend the inertial dynamical approaches for unconstrained convex
optimization problems to affine constrained convex optimization problems.",2106.13702v1
2021-07-01,Event-triggering mechanism to damp the linear wave equation,"This paper aims at proposing a sufficient matrix inequality condition to
carry out the global exponential stability of the wave equation under an
event-triggering mechanism that updates a damping source term. The damping is
distributed in the whole space but sampled in time. The wellposedness of the
closed-loop event-triggered control system is shown. Furthermore, the avoidance
of Zeno behavior is ensured provided that the initial data are more regular.
The interest of the results is drawn through some numerical simulations.",2107.00292v1
2022-01-28,Quantum metrology with a non-linear kicked Mach-Zehnder interferometer,"We study the sensitivity of a Mach-Zehnder interferometer that contains in
addition to the phase shifter a non-linear element. By including both elements
in a cavity or a loop that the light transverses many times, a non-linear
kicked version of the interferometer arises. We study its sensitivity as
function of the phase shift, the kicking strength, the maximally reached
average number of photons, and damping due to photon loss for an initial
coherent state. We find that for vanishing damping Heisenberg-limited scaling
of the sensitivity arises if squeezing dominates the total photon number. For
small to moderate damping rates the non-linear kicks can considerably increase
the sensitivity as measured by the quantum Fisher information per unit time.",2201.12255v1
2022-02-27,The time asymptotic expansion for the compressible Euler equations with time-dependent damping,"In this paper, we study the compressible Euler equations with time-dependent
damping $-\frac{1}{(1+t)^{\lambda}}\rho u$. We propose a time asymptotic
expansion around the self-similar solution of the generalized porous media
equation (GPME) and rigorously justify this expansion as $\lambda \in
(\frac17,1)$. In other word, instead of the self-similar solution of GPME, the
expansion is the best asymptotic profile of the solution to the compressible
Euler equations with time-dependent damping.",2202.13385v1
2022-03-12,Stability for nonlinear wave motions damped by time-dependent frictions,"We are concerned with the dynamical behavior of solutions to semilinear wave
systems with time-varying damping and nonconvex force potential. Our result
shows that the dynamical behavior of solution is asymptotically stable without
any bifurcation and chaos. And it is a sharp condition on the damping
coefficient for the solution to converge to some equilibrium. To illustrate our
theoretical results, we provide some numerical simulations for dissipative
sine-Gordon equation and dissipative Klein-Gordon equation.",2203.06312v1
2022-03-30,A Toy Model for Damped Water Waves,"We consider a toy model for a damped water waves system in a domain $\Omega_t
\subset \mathbb{T} \times \mathbb{R}$. The toy model is based on the
paradifferential water waves equation derived in the work of
Alazard-Burq-Zuily. The form of damping we utilize we utilize is a modified
sponge layer proposed for the three-dimensional water waves system by Clamond,
et. al. We show that, in the case of small Cauchy data, solutions to the toy
model exhibit a quadratic lifespan. This is done via proving energy estimates
with the energy being constructed from appropriately chosen vector fields.",2203.16645v1
2022-05-10,Global attractor for the weakly damped forced Kawahara equation on the torus,"We study the long time behaviour of solutions for the weakly damped forced
Kawahara equation on the torus. More precisely, we prove the existence of a
global attractor in $L^2$, to which as time passes all solutions draw closer.
In fact, we show that the global attractor turns out to lie in a smoother space
$H^2$ and be bounded therein. Further, we give an upper bound of the size of
the attractor in $H^2$ that depends only on the damping parameter and the norm
of the forcing term.",2205.04642v1
2022-06-07,"Decay property of solutions to the wave equation with space-dependent damping, absorbing nonlinearity, and polynomially decaying data","We study the large time behavior of solutions to the semilinear wave equation
with space-dependent damping and absorbing nonlinearity in the whole space or
exterior domains. Our result shows how the amplitude of the damping
coefficient, the power of the nonlinearity, and the decay rate of the initial
data at the spatial infinity determine the decay rates of the energy and the
$L^2$-norm of the solution. In Appendix, we also give a survey of basic results
on the local and global existence of solutions and the properties of weight
functions used in the energy method.",2206.03218v2
2022-10-24,The time asymptotic expansion for the compressible Euler equations with damping,"In 1992, Hsiao and Liu \cite{Hsiao-Liu-1} firstly showed that the solution to
the compressible Euler equations with damping time-asymptotically converges to
the diffusion wave $(\bar v, \bar u)$ of the porous media equation. In
\cite{Geng-Huang-Jin-Wu}, we proposed a time-asymptotic expansion around the
diffusion wave $(\bar v, \bar u)$, which is a better asymptotic profile than
$(\bar v, \bar u)$. In this paper, we rigorously justify the time-asymptotic
expansion by the approximate Green function method and the energy estimates.
Moreover, the large time behavior of the solution to compressible Euler
equations with damping is accurately characterized by the time asymptotic
expansion.",2210.13157v1
2022-12-18,Exponential decay of solutions of damped wave equations in one dimensional space in the $L^p$ framework for various boundary conditions,"We establish the decay of the solutions of the damped wave equations in one
dimensional space for the Dirichlet, Neumann, and dynamic boundary conditions
where the damping coefficient is a function of space and time. The analysis is
based on the study of the corresponding hyperbolic systems associated with the
Riemann invariants. The key ingredient in the study of these systems is the use
of the internal dissipation energy to estimate the difference of solutions with
their mean values in an average sense.",2212.09164v1
2023-02-09,A remark on the logarithmic decay of the damped wave and Schrödinger equations on a compact Riemannian manifold,"In this paper we consider a compact Riemannian manifold (M, g) of class C 1
$\cap$ W 2,$\infty$ and the damped wave or Schr\""odinger equations on M , under
the action of a damping function a = a(x). We establish the following fact: if
the measure of the set {x $\in$ M ; a(x) = 0} is strictly positive, then the
decay in time of the associated energy is at least logarithmic.",2302.04498v1
2023-03-02,Using vibrating wire in non-linear regime as a thermometer in superfluid $^3$He-B,"Vibrating wires are common temperature probes in $^3$He experiments. By
measuring mechanical resonance of a wire driven by AC current in magnetic field
one can directly obtain temperature-dependent viscous damping. This is easy to
do in a linear regime where wire velocity is small enough and damping force is
proportional to velocity. At lowest temperatures in superfluid $^3$He-B a
strong non-linear damping appears and linear regime shrinks to a very small
velocity range. Expanding measurements to the non-linear area can significantly
improve sensitivity. In this note I describe some technical details useful for
analyzing such temperature measurements.",2303.01189v1
2023-04-06,A turbulent study for a damped Navier-Stokes equation: turbulence and problems,"In this article we consider a damped version of the incompressible
Navier-Stokes equations in the whole three-dimensional space with a
divergence-free and time-independent external force. Within the framework of a
well-prepared force and with a particular choice of the damping parameter, when
the Grashof numbers are large enough, we are able to prove some estimates from
below and from above between the fluid characteristic velocity and the energy
dissipation rate according to the Kolmogorov dissipation law. Precisely, our
main contribution concerns the estimate from below which is not often studied
in the existing literature. Moreover, we address some remarks which open the
door to a deep discussion on the validity of this theory of turbulence.",2304.03134v1
2023-05-03,Lyapunov functions for linear damped wave equations in one-dimensional space with dynamic boundary conditions,"We establish the exponential decay of the solutions of the damped wave
equations in one-dimensional space where the damping coefficient is a
nowhere-vanishing function of space. The considered PDE is associated with
several dynamic boundary conditions, also referred to as Wentzell/Ventzel
boundary conditions in the literature. The analysis is based on the
determination of appropriate Lyapunov functions and some further analysis. This
result is associated with a regulation problem inspired by a real experiment
with a proportional-integral control. Some numerical simulations and additional
results on closed wave equations are also provided.",2305.01969v2
2023-05-13,Global existence for a 3D Tropical Climate Model with damping and small initial data in $\dot H^{1/2}(\mathbb{R}^3)$,"We consider a 3D Tropical Climate Model with damping terms in the equation of
the barotropic mode $u$ and in the equation of the first baroclinic mode $v$ of
the velocity. The equation for the temperature $\theta$ is free from dampings.
We prove global existence in time for this system assuming the initial data
$(u_0, v_0,\theta_0)$ small, in terms of the homogeneous space $\dot
H^{1/2}(\mathbb{R}^3)$.",2305.07964v1
2023-07-12,Asymptotic behavior of solutions to the Cauchy problem for 1-D p-system with space dependent damping,"We consider the Cauchy problem for one-dimensional p-system with damping of
space-dependent coefficient. This system models the compressible flow through
porous media in the Lagrangean coordinate. Our concern is an asymptotic
behavior of solutions, which is expected to be the diffusion wave based on the
Darcy law. To show this expectation, the problem is reformulated to the Cauchy
problem for the second order quasilinear hyperbolic equation with space
dependent damping, which is analyzed by the energy method.",2307.05865v1
2023-07-12,Parabolic-elliptic Keller-Segel's system,"We study on the whole space R d the compressible Euler system with damping
coupled to the Poisson equation when the damping coefficient tends towards
infinity. We first prove a result of global existence for the Euler-Poisson
system in the case where the damping is large enough, then, in a second step,
we rigorously justify the passage to the limit to the parabolic-elliptic
Keller-Segel after performing a diffusive rescaling, and get an explicit
convergence rate. The overall study is carried out in 'critical' Besov spaces,
in the spirit of the recent survey [16] by R. Danchin devoted to partially
dissipative systems.",2307.05981v1
2023-07-25,Asymptotic behavior and life-span estimates for the damped inhomogeneous nonlinear Schrödinger equation,"We are interested in the behavior of solutions to the damped inhomogeneous
nonlinear Schr\""odinger equation $ i\partial_tu+\Delta
u+\mu|x|^{-b}|u|^{\alpha}u+iau=0$, $\mu \in\mathbb{C} $, $b>0$, $a \in
\mathbb{C}$ such that $\Re \textit{e}(a) \geq 0$, $\alpha>0$. We establish
lower and upper bound estimates of the life-span. In particular for $a\geq 0$,
we obtain explicit values $a_*,\; a^*$ such that if $a<a_*$ then blow up
occurs, while for $a>a^*,$ global existence holds. Also, we prove scattering
results with precise decay rates for large damping. Some of the results are new
even for $b=0.$",2307.13495v1
2023-07-26,On nonlinear Landau damping and Gevrey regularity,"In this article we study the problem of nonlinear Landau damping for the
Vlasov-Poisson equations on the torus. As our main result we show that for
perturbations initially of size $\epsilon>0$ and time intervals
$(0,\epsilon^{-N})$ one obtains nonlinear stability in regularity classes
larger than Gevrey $3$, uniformly in $\epsilon$. As a complementary result we
construct families of Sobolev regular initial data which exhibit nonlinear
Landau damping. Our proof is based on the methods of Grenier, Nguyen and
Rodnianski.",2307.14271v1
2023-08-18,Damping for fractional wave equations and applications to water waves,"Motivated by numerically modeling surface waves for inviscid Euler equations,
we analyze linear models for damped water waves and establish decay properties
for the energy for sufficiently regular initial configurations. Our findings
give the explicit decay rates for the energy, but do not address
reflection/transmission of waves at the interface of the damping. Still for a
subset of the models considered, this represents the first result proving the
decay of the energy of the surface wave models.",2308.09288v1
2023-08-30,Optimal decay for one-dimensional damped wave equations with potentials via a variant of Nash inequality,"The optimality of decay properties of the one-dimensional damped wave
equations with potentials belonging to a certain class is discussed. The
typical ingredient is a variant of Nash inequality which involves an invariant
measure for the corresponding Schr\""odinger semigroup. This enables us to find
a sharp decay estimate from above. Moreover, the use of a test function method
with the Nash-type inequality provides the decay estimate from below. The
diffusion phenomena for the damped wave equations with potentials are also
considered.",2308.15680v1
2023-09-15,Explicit solutions and linear inviscid damping in the Euler-Boussinesq equation near a stratified Couette flow in the periodic strip,"This short note provides explicit solutions to the linearized Boussinesq
equations around the stably stratified Couette flow posed on
$\mathbb{T}\times\mathbb{R}$. We consider the long-time behavior of such
solutions and prove inviscid damping of the perturbed density and velocity
field for any positive Richardson number, with optimal rates. The explicit
solution is obtained through the limiting absorption principle whereas the
inviscid damping is proved using oscillatory integral methods.",2309.08419v2
2023-09-21,Beyond Qubits : An Extensive Noise Analysis for Qutrit Quantum Teleportation,"The four quantum noises Bit Flip, Phase Flip, Depolarization, and Amplitude
Damping as well as any potential combinations of them are examined in this
papers investigation of quantum teleportation using qutrit states. Among the
above mentioned noises, we observed phase flip has highest fidelity. Compared
to uncorrelated Amplitude Damping, we find that correlated Amplitude Damping
performs two times better. Finally, we agreed that, for better fidelity, it is
preferable to provide the same noise in channel state if noise is unavoidable.",2309.12163v1
2023-12-22,Soliton resolution for the energy critical damped wave equations in the radial case,"We consider energy-critical damped wave equation \begin{equation*}
\partial_{tt}u-\Delta u+\alpha \partial_t u=\left|u\right|^{\frac{4}{D-2}}u
\end{equation*} with radial initial data in dimensions $D\geq 4$. The equation
has a nontrivial radial stationary solution $W$, called the ground state, which
is unique up to sign and scale. We prove that any bounded energy norm solution
behaves asymptotically as a superposition of the modulated ground states and a
radiation term. In the global case, particularly, the solution converges to a
pure multi-bubble due to the damping effect.",2401.04115v2
2024-01-22,Damping-Enhanced Magnon Transmission,"The inevitable Gilbert damping in magnetization dynamics is usually regarded
as detrimental to spin transport. Here we demonstrate in a
ferromagnetic-insulator--normal-metal heterostructure that the strong momentum
dependence and chirality of the eddy-current-induced damping causes also
beneficial scattering properties. Here we show that a potential barrier that
reflects magnon wave packets becomes transparent in the presence of a metallic
cap layer, but only in one direction. We formulate the unidirectional
transmission in terms of a generalized group velocity with an imaginary
component and the magnon skin effect. This trick to turn presumably harmful
dissipation into useful functionalities should be useful for future quantum
magnonic devices.",2401.12022v1
2024-02-18,Sharp lifespan estimate for the compressible Euler system with critical time-dependent damping in $\R^2$,"This paper concerns the long time existence to the smooth solutions of the
compressible Euler system with critical time dependent damping in $\R^2$. We
establish the sharp lifespan estimate from below, with respect to the small
parameter of the initial perturbation. For this end, the vector fields
$\widehat{Z}$ (defined below) are used instead of the usual one $Z$, to get
better decay for the linear error terms. This idea may also apply to the long
time behavior study of nonlinear wave equations with time-dependent damping.",2402.11516v1
2024-02-28,Linear inviscid damping in the presence of an embedding eigenvalue,"In this paper, we investigate the long-time dynamics of the linearized 2-D
Euler equations around a hyperbolic tangent flow $(\tanh y,0)$. A key
difference compared to previous results is that the linearized operator has an
embedding eigenvalue, which has a significant impact on the dynamics of the
linearized system. For the first mode, the dynamics consists of there parts:
non-decay part related to the eigenspace associated with the embedding
eigenvalue, slow decay part due to the resolvent singularity, and fast decay
part related to the inviscid damping. For higher modes, the dynamics is similar
to the inviscid damping phenomena in the case without embedding eigenvalues.",2402.18229v1
2024-03-19,Improved decay results for micropolar flows with nonlinear damping,"We examine the long-time behavior of solutions (and their derivatives) to the
micropolar equations with nonlinear velocity damping. Additionally, we get a
speed-up gain of $ t^{1/2} $ for the angular velocity, consistent with
established findings for classic micropolar flows lacking nonlinear damping.
Consequently, we also obtain a sharper result regarding the asymptotic
stability of the micro-rotational velocity $\ww(\cdot,t)$. Related results of
independent interest are also included.",2403.12885v1
2024-03-26,On a class of nonautonomous quasilinear systems with general time-gradually-degenerate damping,"In this paper, we study two systems with a time-variable coefficient and
general time-gradually-degenerate damping. More explicitly, we construct the
Riemann solutions to the time-variable coefficient Zeldovich approximation and
time-variable coefficient pressureless gas systems both with general
time-gradually-degenerate damping. Applying the method of similar variables and
nonlinear viscosity, we obtain classical Riemann solutions and delta shock wave
solutions.",2403.17732v1
2024-04-09,Phase space contraction of degenerately damped random splittings,"When studying out-of-equilibrium systems, one often excites the dynamics in
some degrees of freedom while removing the excitation in others through
damping. In order for the system to converge to a statistical steady state, the
dynamics must transfer the energy from the excited modes to the dissipative
directions. The precise mechanisms underlying this transfer are of particular
interest and are the topic of this paper. We explore a class of randomly
switched models introduced in [2,3] and provide some of the first results
showing that minimal damping is sufficient to stabilize the system in a fluids
model.",2404.06465v1
2002-11-30,Spacetime-varying couplings and Lorentz violation,"Spacetime-varying coupling constants can be associated with violations of
local Lorentz invariance and CPT symmetry. An analytical supergravity cosmology
with time-varying fine-structure constant provides an explicit example.
Estimates are made for some experimental constraints.",0212003v1
2005-08-29,Lorentz violation as a quantum-gravity signature,"Many theoretical approaches to quantum gravity predict the breakdown of
Lorentz symmetry at Planck energies. Kinematical cosmic-ray studies are a
sensitive tool in the search for such effects. This talk discusses the
construction of test dispersion relations for such analyses.",0508625v1
2005-10-13,Lorentz Invariance Breakdown and Constraints from Big-Bang Nucleosynthesis,"The Standard Model Extension formulated by Colladay and Kosteleck\'y is
reviewed in the framework of the $^4He$ primordial abundance. Upper bounds on
coefficients for the Lorentz violation are derived using the present
observational data.",0510386v1
2007-01-24,REM observations of GRB 060418: the fireball Lorentz factor determination,"We measured the fireball Lorentz factor of GRB 060418 by the direct
observation of the onset of the NIR afterglow carried with the REM telescope.
We found a value of about 400.",0701688v1
2002-09-01,Thermal Superradiance and the Clausius-Mossotti Lorentz-Lorenz Equations,"Electric polarization phenomena in insulating systems have long been
described in mean field theory by the (static) Clausius-Mossotti or (dynamic)
Lorentz-Lorenz polarizabilities. It is here shown, in the strong coupling
regime, that a thermodynamic phase instability exists in these models. The
resulting thermodynamic phase diagram coincides with that obtained from
Dicke-Preparata model of thermal superradiance.",0209017v1
2006-02-20,Fluctuation theorem applied to the Nosé-Hoover thermostated Lorentz gas,"We present numerical evidence supporting the validity of the Gallavotti-Cohen
Fluctuation Theorem applied to the driven Lorentz gas with Nos\'e-Hoover
thermostating. It is moreover argued that the asymptotic form of the
fluctuation formula is independent of the amplitude of the driving force, in
the limit where it is small.",0602458v1
1995-12-07,Possible test of local Lorentz invariance from $τ$ decays,"We analyze the possibility of testing local Lorentz invariance from the
observation of tau decays. Future prospects of probing distances below the
electroweak characteristic scale are discussed.",9512015v2
1997-06-18,Generalization Of Lorentz-Poincare Ether Theory To Quantum Gravity,"We present a quantum theory of gravity which is in agreement with observation
in the relativistic domain. The theory is not relativistic, but a Galilean
invariant generalization of Lorentz-Poincare ether theory to quantum gravity.
  If we apply the methodological rule that the best available theory has to be
preferred, we have to reject the relativistic paradigm and return to Galilean
invariant ether theory.",9706055v1
2001-10-10,Lorentz violations in canonical quantum gravity,"This is a summary of a talk given at the CP01 meeting on possible Lorentz
anomalies in canonical quantum gravity. It briefly reviews some initial
explorations on the subject that have taken place recently, and should be only
be seen as a short pointer to the literature on the subject, mostly for
outsiders.",0110054v1
2002-09-20,Regularity for Lorentz Metrics under Curvature Bounds,"Let (M, g) be an (n+1) dimensional space-time, with bounded curvature with
respect to a bounded framing. If (M, g) is vacuum or satisfies a mild condition
on the stress-energy tensor, then we show that (M, g) locally admits coordinate
systems in which the Lorentz metric is well-controlled in the (space-time)
Sobolev space L^{2,p}, for any finite p.",0209073v1
2003-06-25,Comments on Challenges for Quantum Gravity,"We examine radiative corrections arising from Lorentz violating dimension
five operators presumably associated with Planck scale physics as recently
considered by Myers and Pospelov. We find that observational data result in
bounds on the dimensionless parameters of the order $10^{-15}$. These represent
the most stringent bounds on Lorentz violation to date.",0306113v1
2005-10-10,Reality conditions for Ashtekar gravity from Lorentz-covariant formulation,"We show the equivalence of the Lorentz-covariant canonical formulation
considered for the Immirzi parameter $\beta=i$ to the selfdual Ashtekar
gravity. We also propose to deal with the reality conditions in terms of Dirac
brackets derived from the covariant formulation and defined on an extended
phase space which involves, besides the selfdual variables, also their
anti-selfdual counterparts.",0510050v1
1998-09-29,Testing CPT and Lorentz Symmetry with Neutral-Kaon Oscillations,"In this talk, a brief summary is given of the possibility of using
neutral-kaon oscillations to bound CPT- and Lorentz-breaking parameters in an
extension of the minimal standard model.",9809584v1
1998-09-30,Tests of CPT and Lorentz Symmetry in Penning-Trap Experiments,"This talk discusses the sensitivity of electron-positron and
proton-antiproton Penning-trap experiments to CPT- and Lorentz-violating
effects in the context of an extension of the minimal standard model and
quantum electrodynamics.",9809597v1
1998-10-06,CPT and Lorentz Tests in Hydrogen and Antihydrogen,"Signals for CPT and Lorentz violation at the Planck scale may arise in
hydrogen and antihydrogen spectroscopy. We show that certain 1S-2S and
hyperfine transitions can exhibit theoretically detectable effects unsuppressed
by any power of the fine-structure constant.",9810269v1
1998-11-13,Chern-Simons Violation of Lorentz and PCT Symmetries in Electrodynamics,"Recently proposed Lorentz-PCT noninvariant modifications of electromagnetism
are reviewed. Their experimental consequences are described, and it is argued
that available data decisively rules out their occurrence in Nature.",9811322v1
1999-04-12,Closing the neutrinoless double beta decay window into violations of the equivalence principle and/or Lorentz invariance,"We have examined Lorentz invariance and equivalence principle violations in
the neutrino sector as manifested in neutrinoless double beta decay. We
conclude that this rare decay cannot provide a useful view of these exotic
processes.",9904298v1
2001-04-29,Cross Sections and Lorentz Violation,"The derivation of cross sections and decay rates in the Lorentz-violating
standard-model extension is discussed. General features of the physics are
described, and some conceptual and calculational issues are addressed. As an
illustrative example, the cross section for the specific process of
electron-positron pair annihilation into two photons is obtained.",0104300v1
2002-12-28,Vacuum Photon Splitting in Lorentz-Violating Quantum Electrodynamics,"Radiative corrections arising from Lorentz violation in the fermion sector
induce a nonzero amplitude for vacuum photon splitting. At one loop, the
on-shell amplitude acquires both CPT-even and CPT-odd contributions forbidden
in conventional electrodynamics.",0212382v2
2003-06-20,Probing Lorentz and CPT violation with space-based experiments,"Space-based experiments offer sensitivity to numerous unmeasured effects
involving Lorentz and CPT violation. We provide a classification of clock
sensitivities and present explicit expressions for time variations arising in
such experiments from nonzero coefficients in the Lorentz- and CPT-violating
Standard-Model Extension.",0306190v1
2003-07-11,Tests of Lorentz and CPT Invariance in Space,"I give a brief overview of recent work concerning possible signals of Lorentz
violation in sensitive clock-based experiments in space. The systems under
consideration include atomic clocks and electromagnetic resonators of the type
planned for flight on the International Space Station.",0307161v1
2003-08-28,Lorentz and CPT Violation in the Neutrino Sector,"We consider neutrino oscillations in the minimal Standard-Model Extension
describing general Lorentz and CPT violation. Among the models without neutrino
mass differences is one with two degrees of freedom that reproduces most major
observed features of neutrino behavior.",0308300v2
2003-11-06,Couplings varying on cosmological scales and Lorentz breaking,"In the context of N=4 supergravity in four dimensions, we present an exact
classical solution that leads to spacetime-dependent electromagnetic couplings
and discuss the ensuing Lorentz-violating effects. We comment briefly on
experimental bounds.",0311073v1
2004-01-12,Dirac theory within the Standard-Model Extension,"The modified Dirac equation in the Lorentz-violating Standard-Model Extension
(SME) is considered. Within this framework, the construction of a hermitian
Hamiltonian to all orders in the Lorentz-breaking parameters is investigated,
discrete symmetries and the first-order roots of the dispersion relation are
determined, and various properties of the eigenspinors are discussed.",0401084v1
2004-01-16,The Lorentz-violating Standard-Model Extension,"Quantum-gravity effects are expected to be suppressed by the Planck mass. For
experimental progress it is therefore important to identify potential
signatures from Planck-scale physics that are amenable to ultrahigh-precision
tests. It is argued that minuscule violations of Lorentz and CPT symmetry are
candidate signals. In addition, theoretical and experimental aspects of the
Standard-Model Extension, which describes the emergent low-energy effects, are
discussed.",0401124v1
2004-09-21,Deformed Instantons,"In this talk, instantons are discussed in the presence of Lorentz violation.
Conventional topological arguments are applied to classify the modified
solutions to the Yang-Mills equations according to the topological charge.
Explicit perturbations to the instantons are calculated in detail for the case
of unit topological charge.",0409251v1
2005-02-01,Vector Goldstone Boson and Lorentz Invariance,"Spontanous symmetry breaking usually gives spin 0 Goldstone bosons for the
case of internal symmetries and spin 1/2 fermions for the supersymmetry. The
spontaneous breaking of higher dimensional Lorentz symmetry can give vector
Goldstone boson in 4-dimension.",0502011v1
2006-02-08,Bose-Einstein Condensates as a Probe for Lorentz Violation,"The effects of small Lorentz-violating terms on Bose-Einstein condensates are
analyzed. We find that there are changes to the phase and shape of the
ground-state wave function that vary with the orientation of the trap. In
addition, spin-couplings can act as a source for spontaneous symmetry breaking
in ferromagnetic condensates making them sensitive probes for fundamental
symmetry violation.",0602071v1
2006-07-28,Lorentz Violating Julia-Toulouse Mechanism,"We propose a new Lorentz invariant violating extension for the pure photonic
sector of the Standard Model due to the condensation of topological defects in
the context of the Julia-Toulouse mechanism. Possible physical consequences
leading to direct measurable effects over the confining properties of the
elementary particles are explored.",0607321v1
2006-12-21,Bounds on Spin-Dependent Lorentz Violation From Inverse Compton Observations,"Some of the best bounds on possible Lorentz violation in the electron sector
come from observations of high-energy astrophysical phenomena. Using
measurements of TeV inverse Compton radiation from a number of sources, we
place the first bounds--at the 10^(-15) level--on seven of the electron d
coefficients.",0612288v1
1993-04-03,Algebraic Characterization of the Lorentz and Diffeomorphism Anomalies,"The Wess-Zumino consistency conditions for Lorentz and diffeomorphism
anomalies are discussed by introducing an operator 'delta' which allows to
decompose the exterior derivative as a BRS commutator.",9304007v1
1993-05-28,"Lorentz-Invariant ""Elements of Reality"" and the Question of Joint Measurability of Commuting Observables","It is shown that the joint measurements of some physical variables
corresponding to commuting operators performed on pre- and post-selected
quantum systems invariably disturb each other. The significance of this result
for recent proofs of the impossibility of realistic Lorentz invariant
interpretation of quantum theory (without assumption of locality) is discussed.",9305162v1
1993-08-27,"Strings, Black Holes and Lorentz Contraction","Consistency of quantum mechanics in black hole physics requires unusual
Lorentz transformation properties of the size and shape of physical systems
with momentum beyond the Planck scale. A simple parton model illustrates the
kind of behavior which is needed. It is then shown that conventional
fundamental string theory shares these features.",9308139v1
1995-06-01,Extra dimensions and color confinement,"We consider an extension of the ordinary four dimensional Minkowski space by
introducing additional dimensions which have their own Lorentz transformation.
Particles can transform in a different way under each Lorentz group. We show
that only quark interactions are slightly modified and that color confinement
is automatic since these degrees of freedom run only in the extra dimensions.
No compactification of the extra dimensions is needed.",9506009v1
1995-08-29,The Problem of Constructing the Current Operators in Quantum Field Theory,"Lorentz invariance of the current operators implies that they satisfy the
well-known commutation relations with the representation operators of the
Lorentz group. It is shown that if the standard construction of the current
operators in quantum field theory is used then the commutation relations are
broken by the Schwinger terms.",9508158v1
1997-05-02,Lorentz Symmetry of Supermembrane in Light Cone Gauge Formulation,"We prove the Lorentz symmetry of supermembrane theory in the light cone gauge
to complete the program initiated by de Wit, Marquard and Nicolai. We give some
comments on extending the formulation to the M(atrix) theory.",9705005v2
1999-03-31,Lorentz Invariant Renormalization in Causal Perturbation Theory,"In the framework of causal perturbation theory renormalization consists of
the extension of distributions. We give the explicit form of a Lorentz
invariant extension of a scalar distribution, depending on one difference of
space time coordinates.",9903266v2
1999-12-26,Induced Lorentz and PCT Symmetry Breaking in an External Electromagnetic Field,"In this work we derive the Lorentz-PCT-violating effective action for a
fermion in a constant and uniform electromagnetic field using the
Fock-Schwinger proper time method and extract the exact value of the
coefficient of the nonperturbatively induced Chern-Simons term.",9912251v1
2001-12-04,Can one restore Lorentz invariance in quantum N=2 string?,"We consider quantum N=2 string embedded into the N=4 topological framework
from the perspective of the old covariant quantisation. Making use of the
causality and cyclic symmetry of tree amplitudes we argue that no Lorentz
covariant boson emission vertex can be constructed within the N=4 topological
formalism.",0112024v1
2002-01-15,Lorentz Violation at One Loop,"The proof of one-loop renormalizability of the general Lorentz- and
CPT-violating extension of quantum electrodynamics is described. Application of
the renormalization-group method is discussed and implications for theory and
experiment are considered.",0201097v1
2002-10-29,A remark about unitary representations of Lorentz group and an equation for zero mass particles,"In the present note the expansion of the wave function of a massless particle
(with the definite value of its helicity) over the untary irreducible
representaions of the Lorentz group (defined on the light cone) is used as for
the analog of the Fourier transformation for deriving of an equation in the
relativistic configuration representation.",0210283v1
2003-09-26,Recovering Lorentz Invariance of DLCQ,"We propose a way to recover Lorentz invariance of the perturbative S matrix
in the Discrete Light-Cone Quantization (DLCQ) in the continuum limit without
spoiling the trivial vacuum.",0309240v1
2004-05-14,The Presentation of the Quantum Algebra of Observables of the Closed Bosonic String in 1+3 Dimensions: The Presentation in Manifestly Lorentz Covariant Form,"The quantum algebra of observables of the massive closed bosonic string in
1+3 dimensions has been developed so far in the rest frame of the string. In
this paper a method to write this algebra in a manifestly Lorentz covariant
form is explained and compared with an alternative approach in the literature.",0405133v2
2005-09-09,Spontaneous Lorentz Violation and Nonpolynomial Interactions,"Gauge-noninvariant vector field theories with superficially nonrenormalizable
nonpolynomial interactions are studied. We show that nontrivial relevant and
stable theories have spontaneous Lorentz violation, and we present a large
class of asymptotically free theories. The Nambu-Goldstone modes of these
theories can be identified with the photon, with potential experimental
implications.",0509068v1
2005-12-13,A Lorentz Covariant Noncommutative Geometry,"A noncommutative geometry that preserves lorentz covariance was introduced by
Hartland Snyder in 1947. We show that this geometry has unusual properties
under momentum translation, and derive for it a form of star product.",0512134v1
2006-02-22,Eliminating the CPT-Odd f Coefficient from the Lorentz-Violating Standard Model Extension,"The fermionic f coefficient in the Lorentz-violating standard model extension
presents a puzzle. Thus far, no observable quantity that depends upon f has
ever been found. We show that this is because f is actually unnecessary. It has
absolutely no effects at leading order and can be completely absorbed into
other coefficients of the theory by a redefinition of the field.",0602235v1
2006-10-12,CPT/Lorentz Invariance Violation and Quantum Field Theory,"Analogies between the noncommutative harmonic oscillator and noncommutative
fields are analyzed. Following this analogy we construct examples of quantum
fields theories with explicit CPT and Lorentz symmetry breaking. Some
applications to baryogenesis and neutrino oscillation are also discussed",0610152v1
2007-02-27,Extending the GKZ limit without breaking Lorentz Invariance,"A scenario is presented on how to shift the predicted cutoff in the cosmic
ray spectrum at 10**20 eV, called the Greisen-Zatsepin-Kuzmin limit (GKZ), to
larger energies without breaking the Lorentz invariance. The formulation is
based on a pseudo-complex extension of standard field theory. The dispersion
relation of particles can be changed, leading to a modification of the GKZ
limit. Maximal shifts are determined.",0702208v1
1991-04-29,Interpolation of operators when the extreme spaces are $L^\infty$,"In this paper, equivalence between interpolation properties of linear
operators and monotonicity conditions are studied, for a pair $(X_0,X_1)$ of
rearrangement invariant quasi Banach spaces, when the extreme spaces of the
interpolation are $L^\infty$ and a pair $(A_0,A_1)$ under some assumptions.
Weak and restricted weak intermediate spaces fall in our context. Applications
to classical Lorentz and Lorentz-Orlicz spaces are given.",9201226v1
1999-12-13,Sharp Lorentz space estimates for rough operators,"We demonstrate the $(H^1,L^{1,2})$ or $(L^p,L^{p,2})$ mapping properties of
several rough operators. In all cases these estimates are sharp in the sense
that the Lorentz exponent 2 cannot be replaced by any lower number.",9912098v1
2001-10-11,Multidimensional rearrangement and Lorentz spaces,"We define a multidimensional rearrangement, which is related to classical
inequalities for functions that are monotone in each variable. We prove the
main measure theoretical results of the new theory and characterize the
functional properties of the associated weighted Lorentz spaces.",0110118v1
2003-06-10,Transverse Riemann-Lorentz metrics with tangent radical,"Consider a smooth manifold with a smooth metric which changes bilinear type
from Riemann to Lorentz on a hypersurface $\Sigma$ with radical tangent to
$\Sigma$. Two natural bilinear symmetric forms appear there, and we use it to
analyze the geometry of $\Sigma$. We show the way in which these forms control
the smooth extensibility over $\Sigma$ of the covariant, sectional and Ricci
curvatures of the Levi-Civita connection outside $\Sigma$.",0306153v1
2005-04-08,Affine curvature homogeneous 3-dimensional Lorentz Manifolds,"We study a family of 3-dimensional Lorentz manifolds. Some members of the
family are 0-curvature homogeneous, 1-affine curvature homogeneous, but not
1-curvature homogeneous. Some are 1-curvature homogeneous but not 2-curvature
homogeneous. All are 0-modeled on indecomposible local symmetric spaces. Some
of the members of the family are geodesically complete, others are not. All
have vanishing scalar invariants.",0504163v1
2006-08-29,Weierstrass representation for timelike minimal surfaces in Minkowski 3-space,"Using techniques of integrable systems, we study a Weierstrass representation
formula for timelike surfaces with prescribed mean curvature in Minkowski
3-space. It is shown that timelike minimal surfaces are obtained by integrating
a pair of Lorentz holomorphic and Lorentz antiholomorphic null curves in
Minkowski 3-space. The relationship between timelike minimal surfaces and
bosonic Nambu-Goto string worldsheets in spacetime is also discussed in the
appendix.",0608726v2
2002-03-21,Magnetic monopoles and Lorentz force,"The formulation of a generalized classical electromagnetism that includes
both electric and magnetic charges, is explored in the framework of two
potential approach. It is shown that it is possible to write an action integral
from which one can derive, by least action principle, the symmetrized set of
Maxwell's equations, but also the Lorentz force law by employing the
energy-momentum tensor conservation.",0203043v1
2002-11-29,Elementary Proof of Moretti's Polar Decomposition Theorem for Lorentz Transformations,"A proof more elementary than the original one is given for Moretti's theorem
that the usual polar decomposition of real matrices when applied to an
orthochronous proper Lorentz matrix yields just its standard rotation-boost
decomposition. (The complex SL(2,C) analog is well-known.)",0211077v1
2002-12-12,Fourier Transforms of Lorentz Invariant Functions,"Fourier transforms of Lorentz invariant functions in Minkowski space, with
support on both the timelike and the spacelike domains are performed by means
of direct integration. The cases of 1+1 and 1+2 dimensions are worked out in
detail, and the results for 1+n dimensions are given.",0212040v1
2004-12-01,Wilson Polynomials and the Lorentz Transformation Properties of the Parity Operator,"The parity operator for a parity-symmetric quantum field theory transforms as
an infinite sum of irreducible representations of the homogeneous Lorentz
group. These representations are connected with Wilson polynomials.",0412001v1
2007-01-28,Comparison between Spin and Rotation Properties Of Lorentz Einstein and Reflection Symmetric Transformations,"We have shown that Reflection Symmetric transformation is Lorentz invariant.
It ia also associative. We have also shown that Reflection Symmetric sum of
vectors has a spin-like term comparable to the spin of Dirac eletron. We have
found that the sum is bounded, as a consequence of reflection symmetry. This
boundedness corresponds to Einstein's postulate.",0701067v1
2001-10-26,Derivation of the Lorentz Transformations,"The Lorentz Transformations are derived without any linearity assumptions and
without assuming that y and z coordinates transform in a Galilean manner.
Status of the invariance of the speed of light is reduced from a foundation of
the Special Theory of Relativity to just a property which allows to determine a
value of the physical constant. While high level of rigour is maintained, this
paper should be accessible to a second year university physics student.",0110076v1
2006-01-10,On the possible thermal tachyons,"In this paper the existence of the thermal tachyons i.e. quanta of
temperature field, with is described in the theoretical frame of hyperbolic
thermal equation. The modified Lorentz transformation are developed. It is
argued that thermal tachyons can exist in accordance with modified Lorentz
transformation after change . The thermal tachyons fulfill the hyperbolic heat
transport equation and in principle can be created by attosecond laser pulses.
Key words: Tachyons; Thermal processes; Attosecond laser pulses.",0601064v1
2006-02-08,A brief and transparent derivation of the Lorentz-Einstein transformations via thought experiments,"Starting with a thought experiment proposed by Kard, which derives the
formula that accounts for the relativistic effect of length contraction, we
present a ""two line"" transparent derivation of the Lorentz-Einstein
transformations for the space-time coordinates of the same event. Our
derivation make uses of Einstein's clock synchronization procedure",0602054v1
2006-03-14,An EIT search for Lorentz violating signals,"A test of Lorentz invariance has been performed using an EIT resonance as a
precision frequency discriminator within an Ives-Stilwell like apparatus. We
analyse the experiment within the framework of the Standard Model Extension and
have made the first direct measurment of the parameter
$\kappa_{tr}<1.6\times10^{-5}$.",0603111v2
2006-07-21,On the Non-Lorentz Invariance of M.W. Evans O(3)-Symmetry Law,"Correcting a former proof of M.W. Evans it is shown that his O(3) hypothesis
is not Lorentz invariant and hence no law of Physics.",0607186v4
2006-07-21,"Lorentz and ""apparent"" transformations of the electric and magnetic fields","It is recently discovered that the usual transformations of the
three-dimensional (3D) vectors of the electric and magnetic fields differ from
the Lorentz transformations (LT) (boosts) of the corresponding 4D quantities
that represent the electric and magnetic fields. In this paper, using geometric
algebra formalism, this fundamental difference is examined representing the
electric and magnetic fields by bivectors.",0607189v1
2007-01-24,Some new parallel flows due to Lorentz forces in electrically conducting fluids,"We investigate the fully developed flow between two parallel plates and the
film flow over a plate in an electrically conducting fluid under the action of
a parallel Lorentz force. Exact analytical solutions are derived for velocity,
flow rate and wall shear stress at the plates. The velocity results are
presented in figures. All these flows are new and are presented for the first
time in the literature.",0701279v1
2007-03-09,From E=mc^2 to the Lorentz transformations via the law of addition of relativistic velocities,"In this paper we show how to get the Lorentz transformations from E=mc^2, the
laws of conservation of energy and momentum, and the special relativity
principle. To this end we first deduce the law of addition of relativistic
velocities",0703108v1
1997-08-22,Quantum Lorentz and braided Poincare groups,"Quantum Lorentz groups H admitting quantum Minkowski space V are selected.
Natural structure of a quantum space G = V x H is introduced, defining a
quantum group structure on G only for triangular H (q=1). We show that it
defines a braided quantum group structure on G for |q|=1.",9708025v1
1995-05-31,Geometry of One-Dimensional Wave Propagation,"We investigate the geometrical features of one-dimensional wave propagation,
whose dynamics is described by the (2+1)-dimensional Lorentz group. We find
many interesting geometrical ingredients such as spinorlike behavior of wave
amplitudes, gauge transformations, Bloch-type equations, and Lorentz-group
Berry phases. We also propose an optical experiment to verify these effects.",9505024v1
1995-08-18,Lorentz-invariant Bohmian Mechanics,"A derivation of the Bohm model, and some general comments about it, are
given. A modification of the model which is formally local and
Lorentz-invariant is introduced, and its properties studied for a simple
experiment.",9508014v2
2000-11-09,Lorentz Invariant Superluminal Tunneling,"It is shown that superluminal optical signalling is possible without
violating Lorentz invariance and causality via tunneling through photonic band
gaps in inhomogeneous dielectrics of a special kind.",0011033v3
2002-04-11,"Quantum Jumps, EEQT and the Five Platonic Fractals","It is shown that symmetric configurations of fuzzy spin direction detectors
generate, through quantum jumps, IFS fractals on the sphere S^2. The IFS
fractals can be also interpreted as resulting from applications of Lorentz
boosts to the projective light cone.",0204056v2
2007-04-02,"The Hardy-Lorentz Spaces $H^{p,q}(R^n)$","In this paper we consider the Hardy-Lorentz spaces $H^{p,q}(R^n)$, with
$0<p\le 1$, $0<q\le \infty$. We discuss the atomic decomposition of the
elements in these spaces, their interpolation properties, and the behavior of
singular integrals and other operators acting on them.",0704.0054v1
2007-04-20,Unobservable Higgs Boson and Spontaneous Violation of Lorentz Invariance,"The standard theory of elementary particle physics is modified in such a way
that the Higgs boson becomes unobservable and Lorentz invariance is slightly
violated at the level of the S-matrix. The basic technique of realizing these
properties without violating the unitarity of the physical S-matrix is the use
of the complex-ghost quantum field theory.",0704.2645v2
2007-07-13,The uniqueness of the helicoid in the Lorentz-Minkowski space L3,"In this paper we deal with the uniqueness of the Lorentzian helicoid and
Enneper's surface among properly embedded maximal surfaces with lightlike
boundary of mirror symmetry in the Lorentz-Minkowski space L3.",0707.1946v3
2007-08-30,On the temperature of the moving rod,"In this paper the Lorentz transformation for temperature is derived and
discussed. Considering the hyperbolic heat transport equation it is shown that
T(prim) = gamma T, where gamma is the Lorentz factor, T denotes the temperature
in the rest system and T(prim) is the temperature in the moving system (rod).",0708.4193v1
2007-11-20,Chiral symmetry breaking and Lorentz nature of confinement,"The Lorentz nature of confinement in a heavy-light quarkonium is
investigated. It is demonstrated that an effective scalar interaction is
generated selfconsistently as a result of chiral symmetry breaking, and this
effective scalar interaction is responsible for the QCD string formation
between the quark and the antiquark.",0711.3119v1
2008-05-16,The Lorentz and Levi-Civita Conservation Laws Prohibit the Existence of Black Holes,"To propose that black holes do not exist would be the fundamental way to
resolve the contradiction between event horizons and quantum mechanics. In this
paper we shall use the Lorentz and Levi-Civita conservation laws to explain how
an event horizon might not exist, and the reasons for its nonexistence are
presented by using the theory of classical gravity.",0805.2451v1
2008-05-20,On Decompositions of Lorentz Transformations and their Physical Interpretations,"In a recent article [1] we have explored alternative decompositions of the
Lorentz transformation by adopting the synchronization convention of the target
frame at the end and alternately at the outset. In this note we develop the
decomposition by assuming a correct universal synchronization that may be
outside the two inertial frames that are involved.",0805.3050v1
2008-12-30,Observations on spacetime symmetry and non-commutativity,"We consider both the co-ordinates and momenta to be non-commutative and
define a non-commutative version of Lorentz symmetry which has a smooth limit
to the standard Lorentz symmetry. The Poincar\acute{e} algebra in this
spacetime has also been discussed.",0812.5042v1
2009-02-01,Gravity from Lorentz Symmetry Violation,"In general relativity, the masslessness of gravitons can be traced to
symmetry under diffeomorphisms. Here we consider another possibility, whereby
the masslessness arises from spontaneous violation of Lorentz symmetry.",0902.0083v1
2009-04-01,General theory of Lie derivatives for Lorentz tensors,"We show how the ad hoc prescriptions appeared in 2001 by Ortin for the Lie
derivative of Lorentz tensors are a direct consequence of the Kosmann lift
defined earlier in 1996 in a much more general setting encompassing older
results of Y. Kosmann in 1971.",0904.0258v2
2009-05-21,Diffeomorphism-invariant noncommutative gravity with twisted local Lorentz invariance,"We propose a new theory of gravitation on noncommutative space-time which is
invariant under the general coordinate transformations, while the local Lorentz
invariance is realized as twisted gauge symmetry. Our theory is remarkably
simpler compared to the existing formulations of noncommutative gravity.",0905.3427v2
2009-11-25,Democracy functions and optimal embeddings for approximation spaces,"We prove optimal embeddings for nonlinear approximation spaces in terms of
weighted Lorentz sequence spaces, with the weights depending on the democracy
functions of the basis. As applications we recover known embeddings for
$N$-term wavelet approximation in Lebesgue, Orlicz, and Lorentz norms. We also
study the ""greedy classes"" introduced by Gribonval and Nielsen.",0911.4900v1
2010-02-26,Testing Local Lorentz Invariance with high-accuracy astrometric observations,"This paper summarizes the analysis of the consequences of the violation of
the Local Lorentz Invariance (LLI) on astrometric observations. We demonstrate
that from the point of view of the LLI astrometric observations represent an
experiment of Michelson-Morley type. The future high-accuracy astrometric
projects (e.g., Gaia) will be used to test the LLI.",1002.5016v1
2010-08-02,A monopole solution in a Lorentz-violating field theory,"I present a topological defect solution that arises in a theory where Lorentz
symmetry is spontaneously broken by a rank-two antisymmetric tensor field, and
I discuss its observational signatures.",1008.0324v1
2010-08-05,Energy Transfer and Joint Diffusion,"A paradigm model is suggested for describing the diffusive limit of
trajectories of two Lorentz disks moving in a finite horizon periodic
configuration of smooth, strictly convex scatterers and interacting with each
other via elastic collisions. For this model the diffusive limit of the two
trajectories is a mixture of joint Gaussian laws (analogous behavior is
expected for the mechanical model of two Lorentz disks).",1008.0940v1
2010-08-10,Tests of Lorentz symmetry,"A number of approaches to fundamental physics can lead to the violation of
Lorentz and CPT symmetry. This talk discusses the low-energy phenomenology
associated with such effects and reviews various sample experiments within this
context.",1008.1746v1
2010-08-30,Classical kinematics for Lorentz violation,"Classical point-particle relativistic lagrangians are constructed that
generate the momentum-velocity and dispersion relations for quantum wave
packets in Lorentz-violating effective field theory.",1008.5062v1
2010-09-03,Charge conjugation from space-time inversion in QED: discrete and continuous groups,"We show that the CPT groups of QED emerge naturally from the PT and P (or T)
subgroups of the Lorentz group. We also find relationships between these
discrete groups and continuous groups, like the connected Lorentz and
Poincar\'e groups and their universal coverings.",1009.0774v1
2010-09-05,Results of Evolution Supervised by Genetic Algorithms,"A series of results of evolution supervised by genetic algorithms with
interest to agricultural and horticultural fields are reviewed. New obtained
original results from the use of genetic algorithms on structure-activity
relationships are reported.",1009.0915v1
2011-04-08,Mass Hierarchies in Lorentz-Violation-induced Dynamical Mass Models,"We discuss the issue of fermion mass hierarchies between lepton and quark
families in toy models of dynamical generation of fermion masses through
minimal Lorentz Invariance Violation. Realistic hierarchies in chiral theories
necessitate an extended gauge structure, which includes both vector and
axial-vector interactions.",1104.1583v1
2011-05-19,Lorentz space estimates for the Coulombian renormalized energy,"In this paper we obtain optimal estimates for the ""currents"" associated to
point masses in the plane, in terms of the Coulombian renormalized energy of
Sandier-Serfaty \cite{ss1,ss3}. To derive the estimates, we use a technique
that we introduced in \cite{st}, which couples the ""ball construction method""
to estimates in the Lorentz space $L^{2,\infty}$.",1105.3960v1
2011-06-21,On homogeneous Hermite-Lorentz spaces,"We define naturally Hermite-Lorentz metrics on almost-complex manifolds as
special case of pseudo-Riemannian metrics compatible with the almost complex
structure. We study their isometry groups.",1106.4145v3
2011-06-29,Anisotropic collective flow of a Lorentz gas,"Analytical results for the anisotropic collective flow of a Lorentz gas of
massless particles scattering on fixed centres are presented.",1106.6009v2
2011-10-05,Could the dynamical Lorentz symmetry breaking induce the superluminal neutrinos?,"The toy fermion model coupled with Lagrange multiplier constraint field is
proposed. The possibility of superluminal neutrino propagation as result of
dynamical Lorentz symmetry breaking is studied.",1110.0889v2
2012-02-14,An analytic approximation to the Diffusion Coefficient for the periodic Lorentz Gas,"An approximate stochastic model for the topological dynamics of the periodic
triangular Lorentz gas is constructed. The model, together with an extremum
principle, is used to find a closed form approximation to the diffusion
coefficient as a function of the lattice spacing. This approximation is
superior to the popular Machta and Zwanzig result and agrees well with a range
of numerical estimates.",1202.2904v1
2012-03-22,Optical-cavity tests of higher-order Lorentz violation,"The effects of Lorentz-violating operators of nonrenormalizable dimension in
optical resonate cavities are studied. Optical-frequency experiments are shown
to provide sensitivity to nondispersive nonbirefringent violations that is many
orders of magnitude beyond current constraints from microwave cavities.
Existing experiments based on Fabry-Perot and ring resonators are considered as
illustrations.",1203.5331v2
2012-06-20,On the superfield supersymmetric aether-like Lorentz-breaking models,"Within the superfield approach, we formulate the superfield supersymmetric
aether-like Lorentz-breaking models, both in three- and in four-dimensional
cases.",1206.4508v2
2012-09-04,Bipartite Riemann-Finsler geometry and Lorentz violation,"Bipartite Riemann-Finsler geometries with complementary Finsler structures
are constructed. Calculable examples are presented based on a bilinear-form
coefficient for explicit Lorentz violation.",1209.0750v1
2012-10-01,Lorentz Connections and Gravitation,"The different roles played by Lorentz connections in general relativity and
in teleparallel gravity are reviewed. Some of the consequences of this
difference are discussed.",1210.0379v1
2012-10-09,Cosmological Implications of a Lorentz Invariance Violating O(2) Model,"We derive the free energy of a Lorentz invariance violating (LIV) O(2) model,
for which a non-vanishing commutator among it's momenta is supposed. Then we
investigate the possible implications of such a matter field on the time
evolution of a flat FRW universe at low and high temperatures.",1210.2513v1
2012-10-14,Variations on the adiabatic invariance: the Lorentz pendulum,"We analyze a very simple variant of the Lorentz pendulum, in which the length
is varied exponentially, instead of uniformly, as it is assumed in the standard
case. We establish quantitative criteria for the condition of adiabatic changes
in both pendula and put in evidence their substantially different physical
behavior with regard to adiabatic invariance.",1210.4241v1
2012-10-19,Canonical Solutions to Nonconvex Minimization Problems over Lorentz Cone,"This paper presents a canonical dual approach for solving nonconvex quadratic
minimization problem. By using the canonical duality theory, nonconvex primal
minimization problems over n-dimensional Lorentz cone can be transformed into
certain canonical dual problems with only one dual variable, which can be
solved by using standard convex minimization methods. Extremality conditions of
these solutions are classified by the triality theory. Applications are
illustrated.",1210.5300v1
2012-11-14,On the higher-derivative Lorentz-breaking terms,"The first one-loop higher-derivative contribution to the effective action of
the Lorentz-breaking spinor QED is obtained and shown to be finite and
ambiguous.",1211.3363v1
2012-12-07,"Antimatter, the SME, and Gravity","A general field-theoretic framework for the analysis of CPT and Lorentz
violation is provided by the Standard-Model Extension (SME). This work
discusses a number of SME-based proposals for tests of CPT and Lorentz
symmetry, including antihydrogen spectroscopy and antimatter gravity tests.",1212.1636v1
2012-12-24,Coupling Right- and Left-Handed Photons Differently to Charged Matter,"We consider a modification of electrodynamics in which right- and
left-circularly polarized photons are coupled to charged sources differently.
Even though photon helicity is a Lorentz invariant quantity, such a
modification breaks Lorentz symmetry, as well as locality. The modified theory
includes novel magnetic forces between perpendicular currents. Existing data
can be used to constrain the modification at approximately a 2 x 10^(-3) level.",1212.5967v1
2013-02-09,Consequences of Spontaneous Lorentz Violation in Gravity,"A brief summary of some of the main consequences of spontaneous Lorentz
violation in gravity is presented, including evasion of a no-go theorem,
concomitant spontaneous diffeomorphism breaking, the appearance of massless
Nambu-Goldstone modes and massive Higgs modes, and the possibility of a Higgs
mechanism in gravity.",1302.2278v1
2013-02-18,Embedded triply periodic zero mean curvature surfaces of mixed type in Lorentz-Minkowski 3-space,"We construct embedded triply periodic zero mean curvature surfaces of mixed
type in the Lorentz-Minkowski 3-space with the same topology as the Schwarz D
surface in the Euclidean 3-space.",1302.4315v1
2013-04-03,Self-intersections of trajectories of Lorentz process,"We study the asymptotic behaviour of the number of self-intersections of a
trajectory of a periodic planar Lorentz process with strictly convex obstacles
and finite horizon. We give precise estimates for its expectation and its
variance. As a consequence, we establish the almost sure convergence of the
self-intersections with a suitable normalization.",1304.0884v1
2013-04-29,"(T,L)-type rotational surface in three dimensional Lorentz-Minkowski space","We study the third Laplace-Beltrami operator of timelike rotational surface
of (T,L)-type in three dimensional Lorentz-Minkowski space.",1304.7657v3
2013-05-18,Effects of Lorentz violation through the $γe\to Wν_e$ process in the Standard Model Extension,"Physics beyond the Fermi scale could show up through deviations of the gauge
couplings predicted by the electroweak Yang-Mills sector. This possibility is
explored in the context of the International Linear Collider (ILC) through the
helicity amplitudes for the gamma e -> W nu_e reaction to which contributes the
trilinear WWgamma coupling. The new physics effects on this vertex are
parametrized in a model-independent fashion through an effective electroweak
Yang-Mills sector, which is constructed by considering two essentially
different sources of new physics. In one scenario, Lorentz violation will be
considered exclusively as the source of new physics effects. This type of new
physics is considered in an extension of the Standard Model that is known as
the Standard Model Extension (SME), which is an effective field theory that
contemplates CPT and Lorentz violation in a model-independent fashion. Any
source of new physics that respects the Lorentz symmetry, will be considered
within the general context of the well known Conventional Effective Standard
Model (CESM) extension. Both the SME and the CESM descriptions include gauge
invariant operators of dimension higher than four, which, in general, transform
as Lorentz tensors of rank higher than zero. Whereas in the former theory
observer Lorentz invariants are constructed by contracting these operators with
constant Lorentz tensors, in the latter the corresponding Lorentz invariant
interactions are obtained contracting such operators with products of the
metric tensor. We focus our study on the possibility of experimentally
distinguish both types of new physics effects on the WWgamma vertex. It is
found that for a new physics scale of the same order of magnitude and under
determined circumstances, both types of new physics effects will be clearly
distinguished.",1305.4265v1
2013-07-15,Dependence of the Gauss-Codazzi equations and the Ricci equation of Lorentz surfaces,"The fundamental equations of Gauss, Codazzi and Ricci provide the conditions
for local isometric embeddability. In general, the three fundamental equations
are independent for surfaces in Riemannian 4-manifolds. In contrast, we prove
in this article that for arbitrary Lorentz surfaces in Lorentzian Kaehler
surfaces the equation of Ricci is a consequence of the equations of Gauss and
Codazzi.",1307.3971v1
2013-07-17,Inequalities for convolutions of functions on commutative hypergroups,"The generalized Young inequality on the Lorentz spaces for commutative
hypergroups is introdused and an application of it is given to the theory of
fractional integrals. The boundedness on the Lorentz space and the
Hardy-Littlewood-Sobolev theorem for the fractional integrals on the
commutative hypergroups is proved.",1307.4948v1
2013-07-18,Lorentz violation in a uniform gravitational field,"We present a method to calculate the nonrelativistic hamiltonian for the
minimal Standard-Model Extension matter sector in a uniform gravitational
field. The resulting hamiltonian coincides with earlier results in the
corresponding limits but it also includes spin-dependent terms that were
previously unknown. The phenomenology associated with this hamiltonian is
briefly discussed.",1307.4997v1
2013-10-04,"Associated Spaces of Generalized Classical Lorentz Spaces $GΛ_{p,ψ;\varphi}$","In this paper we have calculated the associate norms of the
$G\Lambda_{p,\psi;\varphi}$ generalized classical Lorentz spaces.",1310.1169v2
2013-10-30,Sharp decay estimates in Lorentz spaces for nonnegative Schrödinger heat semigroups,"Let $H:=-\Delta+V$ be a nonnegative Schr\""odinger operator on $L^2({\bf
R}^N)$, where $N\ge 2$ and $V$ is a radially symmetric function decaying
quadratically at the space infinity. In this paper we consider the
Schr\""odinger heat semigroup $e^{-tH}$, and make a complete table of the decay
rates of the operator norms of $e^{-tH}$ in the Lorentz spaces as $t\to\infty$.",1310.8074v1
2014-04-14,Lorentz Invariance in Shape Dynamics,"Shape dynamics is a reframing of canonical general relativity in which time
reparametrization invariance is ""traded"" for a local conformal invariance. We
explore the emergence of Lorentz invariance in this model in three contexts: as
a maximal symmetry, an asymptotic symmetry, and a local invariance.",1404.3696v2
2014-08-05,Kink in superconducting cosmic string: exact solution,"We solve the equations of motion and find the Lorentz transformation
associated with a kink in superconducting cosmic string. The kink velocity does
not depend on its amplitude. The kink amplitude cannot be arbitrary but it
varies within definite range and determines the explicit form of the relevant
Lorentz transformation.",1409.1896v3
2014-10-02,Lorentz-violating photons with a mass term,"Perturbative calculations in quantum field theory often require the
regularization of infrared divergences. In quantum electrodynamics, such a
regularization can for example be accomplished by a photon mass introduced via
the Stueckelberg method. The present work extends this method to the QED limit
of the Lorentz- and CPT-violating Standard-Model Extension.",1410.0636v1
2014-11-10,Similarity Transformations of the Lorentz Transformation,"We supplement the Lorentz transform $L(v)$ with a new ""Tunneling"" transform
$T(v)$. Application of this new transform to elementary quantum mechanics
offers a novel, intuitive insight into the nature of quantum tunneling; in
particular, the so called ""Klein Paradox"" is discussed.",1411.2586v3
2014-12-12,Average Lorentz Self-Force From Electric Field Lines,"We generalize the derivation of electromagnetic fields of a charged particle
moving with a constant acceleration [1] to a variable acceleration (piecewise
constants) over a small finite time interval using Coulomb's law, relativistic
transformations of electromagnetic fields and Thomson's construction [2]. We
derive the average Lorentz self-force for a charged particle in arbitrary
non-relativistic motion via averaging the fields at retarded time.",1412.3942v1
2015-01-27,"Antimatter-Gravity Couplings, and Lorentz Symmetry","Implications of possible CPT and Lorentz violation for antimatter-gravity
experiments as well as other antimatter tests are considered in the context of
the general field-theory-based framework of the Standard-Model Extension (SME).",1501.06877v1
2015-01-31,Some intersections of Lorentz spaces,"Let (X,\mu) be a measure space. For p, q\in (0,\infty] and arbitrary subsets
P,Q of (0,\infty], we introduce and characterize some intersections of Lorentz
spaces, denoted by ILp,Q(X,\mu), ILJ,q(X,\mu) and ILJ,Q(X,\mu).",1502.00159v1
2015-03-24,"Bosonic and fermionic Weinberg-Joos (j,0)+ (0,j) states of arbitrary spins as Lorentz-tensors or tensor-spinors and second order theory","We propose a general method for the description of arbitrary single spin-j
states transforming according to (j,0)+(0,j) carrier spaces of the Lorentz
algebra in terms of Lorentz-tensors for bosons, and tensor-spinors for
fermions, and by means of second order Lagrangians. The method allows to avoid
the cumbersome matrix calculus and higher \partial^{2j} order wave equations
inherent to the Weinberg-Joos approach. We start with reducible Lorentz-tensor
(tensor-spinor) representation spaces hosting one sole (j,0)+(0,j) irreducible
sector and design there a representation reduction algorithm based on one of
the Casimir invariants of the Lorentz algebra. This algorithm allows us to
separate neatly the pure spin-j sector of interest from the rest, while
preserving the separate Lorentz- and Dirac indexes. However, the Lorentz
invariants are momentum independent and do not provide wave equations. Genuine
wave equations are obtained by conditioning the Lorentz-tensors under
consideration to satisfy the Klein-Gordon equation. In so doing, one always
ends up with wave equations and associated Lagrangians that are second order in
the momenta. Specifically, a spin-3/2 particle transforming as (3/2,0)+ (0,3/2)
is comfortably described by a second order Lagrangian in the basis of the
totally antisymmetric Lorentz tensor-spinor of second rank, \Psi_[ \mu\nu].
Moreover, the particle is shown to propagate causally within an electromagnetic
background. In our study of (3/2,0)+(0,3/2) as part of \Psi_[\mu\nu] we
reproduce the electromagnetic multipole moments known from the Weinberg-Joos
theory. We also find a Compton differential cross section that satisfies
unitarity in forward direction. The suggested tensor calculus presents itself
very computer friendly with respect to the symbolic software FeynCalc.",1503.07230v1
2014-12-29,Schrodinger/Milne Big Bang. Creating a 'Universe of Threeness',"A Schrodinger-evolving forward/lightcone-interior 'Milne' universe ('SMU') is
governed by 'entered-Lorentz' (CL) symmetry/that of a 9 parameter Lie group
with a 6 parameter SL(2,c) 'exterior' and a 3 parameter 'quality space' center.
'Reality' resides in current densities of electric charge and energy
momentum/the Dalembertian of an SMU ray specified classical retarded Lorentz
tensor field with 22 electromagnetic and 32 gravitational components.",1504.04032v2
2015-05-12,Discrete line integral method for the Lorentz force system,"In this paper, we apply the Boole discrete line integral to solve the Lorentz
force system which is written as a non-canonical Hamiltonian system. The method
is exactly energy-conserving for polynomial Hamiltonians of degree $\nu \leq
4$. In any other case, the energy can also be conserved approximatively. With
comparison to well-used Boris method, numerical experiments are presented to
demonstrate the energy-preserving property of the method.",1505.02962v1
2015-07-28,Lorentz violation in gravity,"The study of gravitational theories without Lorentz invariance plays an
important role to understand different aspects of gravitation. In this short
contribution we will describe the construction, main advantages and some
phenomenological considerations associated with the presence of a preferred
time direction.",1507.07687v1
2015-08-01,Quaternion Generalization of Super Poincare Group,"Super Poincare algebra in D = 6 space-time dimensions has been analysed in
terms of quaternion analyticity of Lorentz group. Starting the connection of
quaternion Lorentz group with SO(1; 5) group, the SL(2;H) spinors for Dirac &
Weyl representations of Poincare group are described consistently to extend the
Poincare algebra to Super Poincare algebra for D = 6 space-time.",1508.05368v1
2015-09-09,On a sidereal time variation of the Lorentz force,"We consider a search for a sidereal time variation of the beam trajectory in
the cyclotron motion in a static magnetic field. The combination of two beams
moving in opposite directions could allow a test of the radius stability with
sensitivity approaching $10^{-10}$. Such a level of variation of the Lorentz
force, if it exists, would require a speed of light anisotropy on the level of
$10^{-18}$.",1509.02754v1
2015-10-12,A gauge theory of massive spin one particles,"An Abelian gauge theory describing dynamics of massive spin one bosons is
constructed. This is achieved by appending to the Maxwell action, a gauge
invariant mass term. The theory is quantised in temporal as well as Lorentz
gauge, and the corresponding Hilbert spaces are constructed. In both the
gauges, it is found that, the theory respects Lorentz invariance, locality,
causality and unitarity.",1510.03213v1
2016-01-18,Theory of optimal transport for Lorentzian cost functions,"The optimal transport problem is studied in the context of Lorentz-Finsler
geometry. For globally hyperbolic Lorentz-Finsler spacetimes the first
Kantorovich problem and the Monge problem are solved. Further the intermediate
regularity of the transport paths is studied. These results generalize parts of
Bertrand & Puel and Brenier et al.",1601.04532v2
2016-01-20,Lorentzian Darboux images of curves on spacelike surfaces in Lorentz-Minkowski 3-space,"For a regular curve on a spacelike surface in Lorentz-Minkowski $3$-space, we
have a moving frame along the curve which is called a Lorentzian Darboux frame.
We introduce five special vector fields along the curve associated to the
Lorentzian Darboux frame and investigate their singularities.",1601.05175v1
2016-02-16,Weighted inequalities for quasilinear integral operators on the semiaxis and application to the Lorentz spaces,"Weighted $L^p-L^r$ inequalities with arbitrary measurable non-negative
weights for positive quasilinear integral operators with Oinarov's kernel on
the semiaxis are characterized. Application to the boundedness of maximal
operator in the Lorentz $\Gamma-$spaces is given.",1602.04884v1
2016-03-28,Anomalous pinch of turbulent plasmas driven by the magnetic-drift-induced Lorentz force through the Stokes-Einstein relation,"It is found that the Lorentz force generated by the magnetic drift drives a
generic plasma pinch fluxes of particle, energy and momentum through the
Stokes-Einstein relation. The proposed theoretical model applies for both
electrons and ions, trapped particles and passing particles.",1603.08319v1
2016-04-20,The Lorentz Force and Energy-Momentum for Off-Shell Electromagnetism,"The kinematics of pre-Maxwell electrodynamics is examined and interpretations
of these fields is found through an examination of the associated Lorentz force
and the structure of the energy-momentum tensor.",1604.06745v1
2016-07-25,Gravity Sector of the SME,"In this talk, the gravity sector of the effective field theory description of
local Lorentz violation is discussed, including minimal and nonminimal
curvature couplings. Also, recent experimental and observational analyses
including solar-system ephemeris and short-range gravity tests are reviewed.",1607.07113v1
2016-07-25,Searches for exotic interactions with the nEDM experiment,"Ultracold neutrons were used to search for signals indicating the violation
of Lorentz and CPT invariance or the existence of dark matter using the
spectrometer to search for an electric dipole moment of the neutron.",1607.07293v1
2016-07-27,Limits on Spherical Coefficients in the Minimal-SME Photon Sector,"We place limits on spherical coefficients for Lorentz violation involving
operators of dimension four in the photon sector of the minimal Standard-Model
Extension. The bounds are deduced from existing experimental results with
optical-cavity oscillators.",1607.08252v1
2016-07-28,The number of catenoids connecting two coaxial circles in Lorentz-Minkowski space,"In 3-dimensional Lorentz-Minkowski space we determine the number of catenoids
connecting two coaxial circles in parallel planes. This study is separated
according to the types of circles and the causal character (spacelike and
timelike) of the catenoid.",1607.08428v1
2016-09-29,Testing Lorentz and CPT invariance with neutrinos,"Neutrino experiments can be considered sensitive tools to test Lorentz and
CPT invariance. Taking advantage of the great variety of neutrino experiments,
including neutrino oscillations, weak decays, and astrophysical neutrinos, the
generic experimental signatures of the breakdown of these fundamental
symmetries in the neutrino sector are presented.",1609.09474v1
2017-08-10,"Antimatter, Lorentz Symmetry, and Gravity","A brief introduction to the Standard-Model Extension (SME) approach to
testing CPT and Lorentz symmetry is provided. Recent proposals for tests with
antimatter are summarized, including gravitational and spectroscopic tests.",1708.03213v1
2018-02-01,A few notes on Lorentz spaces,"In the sequel, we recall and comment some classical results on the
non-increasing rearrangement and Lorentz spaces. There are papers in the
existing literature that seemed to have been bypassed as regards its
contractive property in~$L^p$ spaces. Also, we provide detailed proofs and some
properties that does not seem to arise in the existing literature.",1802.00244v1
2013-08-06,Status of Matter-Gravity Couplings in the SME,"Constraints on Lorentz violation in matter-gravity couplings are summarized
along with existing proposals to obtain sensitivities that exceed current
limits by up to 11 orders of magnitude.",1308.1171v1
2013-08-14,Who Ordered the Anti-de Sitter Tangent Group?,"General relativity can be unambiguously formulated with Lorentz, de Sitter
and anti-de Sitter tangent groups, which determine the fermionic
representations. We show that besides of the Lorentz group only anti-de Sitter
tangent group is consistent with all physical requirements.",1308.3199v1
2014-03-07,Mass Renormalization in Lorentz-violating Scalar Field Theory,"In this work we evaluate the $\gamma_{m}$ function corresponding to mass
renormalization for O($N$) scalar field theory with Lorentz violation. We
calculate this function up to two-loop order for a theory renormalized
utilizing the counterterm method in the minimal subtraction scheme with Feynman
diagrams regularized using dimensional regularization.",1403.1826v1
2014-03-22,A Simple Derivation of Lorentz Self Force,"We derive the Lorentz self force for an arbitrarily moving charged particle
via averaging the retarded fields. The derivation is simple and at the same
time pedagogically accessible. We obtain the radiation reaction for a charged
particle moving in a conic. We pin down the underlying concept of mass
renormalization.",1403.5622v2
2014-03-24,Field sources in a Lorentz symmetry breaking scenario with a single background vector,"This paper is devoted to investigating the interactions between stationary
sources of the electromagnetic field, in a model which exhibits explicit
Lorentz-symmetry breaking due to the presence of a single background vector. We
focus on physical phenomena that emerge from this kind of breaking and which
have no counterpart in Maxwell Electrodynamics.",1403.5953v1
2008-07-11,A Lorentz and gauge invariant measure of laser intensity,"Focussing on null fields as simple models of laser beams we discuss the
classical relativistic motion of charges in strong electromagnetic fields. We
suggest a universal, Lorentz and gauge invariant measure of laser intensity and
explicitly calculate and interpret it for crossed field, plane wave and vortex
models.",0807.1841v1
2008-07-28,Multilinear Hölder-type inequalities on Lorentz sequence spaces,"We establish H\""older type inequalities for Lorentz sequence spaces and their
duals. In order to achieve these and some related inequalities, we study
diagonal multilinear forms in general sequence spaces, and obtain estimates for
their norms. We also consider norms of multilinear forms in different Banach
multilinear ideals.",0807.4392v1
2012-01-18,Classical Lagrangians for Momentum Dependent Lorentz Violation,"Certain momentum-dependent terms in the fermion sector of the
Lorentz-violating Standard Model Extension (SME) yield solvable classical
lagrangians of a type not mentioned in the literature. These cases yield new
relatively simple examples of Finsler and pseudo-Finsler structures. One of the
cases involves antisymmetric $d$-type terms and yields a new example of a
relatively simple covariant lagrangian.",1201.3931v1
2014-06-11,Inequalities for Lorentz polynomials,"We prove a few interesting inequalities for Lorentz polynomials including
Nikolskii-type inequalities. A highlight of the paper is a sharp Markov-type
inequality for polynomials of degree at most n with real coefficients and with
derivative not vanishing in the open unit disk. The result may be compared with
Erdos's classical Markov-type inequality (1940) for polynomials of degree at
most n having only real zeros outside the interval (-1,1).",1406.2843v1
2014-06-18,Zero density of open paths in the Lorentz mirror model for arbitrary mirror probability,"We show, incorporating results obtained from numerical simulations, that in
the Lorentz mirror model, the density of open paths in any finite box tends to
0 as the box size tends to infinity, for any mirror probability.",1406.4796v1
2016-05-13,Cosmological constraints on Lorentz Invariance violation in gravity and dark matter,"This brief contribution is devoted to phenomenological consequences of
deviations from Lorentz invariance in gravity and dark matter. We will discuss
main effects on cosmological observables and current constraints derived from
astrophysical and cosmological data.",1605.04168v1
2016-08-05,"Pre-potential in the $AdS_{5}\,\times\,S^{5}$ Type IIB superspace","We found the pre-potential in the superspace with $AdS_{5}\,\times\,S^{5}$
background. The pre-potential appears as part of the vielbeins, without
derivatives. The space-cone gauge destroys the bulk Lorentz covariance, but
still preserves boundary Lorentz covariance (projective superspace)
$SO\,(\,3,\,1\,)\,\otimes\,SO\,(\,4\,)$, i.e. symmetries of boundary CFT are
manifest.",1608.02036v1
2016-12-07,Lorentz Force and Ponderomotive Force in the Presence of a Minimal Length,"In this work, according to the electromagnetic field tensor in the framework
of generalized uncertainty principle (GUP), we obtain the Lorentz force and
Faraday's law of induction in the presence of a minimal length. Also, the
ponderomotive force and pomderomotive pressure in the presence of a measurable
minimal length are found.",1612.03739v1
2016-12-27,Constraints on Nonmetricity from Bounds on Lorentz Violation,"Spacetime nonmetricity can be studied experimentally through its couplings to
fermions and photons. We use recent high-precision searches for Lorentz
violation to deduce first constraints involving the 40 independent nonmetricity
components down to levels of order $10^{-43}$ GeV.",1612.08744v1
2017-12-06,Spacelike radial graphs of prescribed mean curvature in the Lorentz-Minkowski space,"In this paper we investigate the existence and uniqueness of spacelike radial
graphs of prescribed mean curvature in the Lorentz-Minkowski space
$\mathbb{L}^{n+1}$, for $n\geq 2$, spanning a given boundary datum lying on the
hyperbolic space $\mathbb{H}^n$.",1712.02114v2
2017-12-29,Lorentz and Diffeomorphism Violations in Linearized Gravity,"Lorentz and diffeomorphism violations are studied in linearized gravity using
effective field theory. A classification of all gauge-invariant and
gauge-violating terms is given. The exact covariant dispersion relation for
gravitational modes involving operators of arbitrary mass dimension is
constructed, and various special limits are discussed.",1712.10268v1
2019-06-20,Recent Developments in Spacetime-Symmetry tests in Gravity,"We summarize theoretical and experimental work on tests of CPT and local
Lorentz symmetry in gravity. Recent developments include extending the
effective field theory framework into the nonlinear regime of gravity.",1906.08657v2
2019-09-17,Inclusion theorems for grand Lorentz spaces,"In this paper, we consider some inclusion theorems for grand Lorentz spaces
$L^{p,q)}\left( X,\mu \right) $ and $\Lambda _{p),\omega }$ where $\mu $ is a
finite measure on $\left( X,\Sigma \right) .$ Moreover, we consider the problem
of the convergence of approximate identities in these spaces.",1909.07743v1
2020-01-10,Lorentz invariance relations for twist-3 quark distributions,"We calculate twist-3 parton ditribution functions (PDFs) using cut and uncut
diagrams. Uncut diagrams lead to a Dirac delta function term. No such term
appears when cut diagrams are used. We show that a $\delta(x)$ is necessary to
satisfy the Lorentz invariance relations of twist-3 PDFs, except for the
Burkhardt-Cottingham sum rule in QCD.",2001.03655v1
2020-04-12,Lorentz-violating scalar QED renormalization,"This paper presents divergent contributions of the radiative corrections for
a Lorentz-violating extension of the scalar electrodynamics. We initially
discuss some features of the model and extract the Feynman rules. Then we
compute the one-loop radiative corrections using Feynman parametrization and
dimensional regularization in order to evaluate the integrals. We also discuss
Furry's theorem validity and renormalization in the present context.",2004.05680v1
2012-05-19,Distribution fitting 16. How many colors are actually in the field?,"A study to compare different methods of estimation was conducted. The goal
was to provide an estimate for the number of petal colors existing in the field
by using a random sample of Lycoris longituba flowers taken from the field. The
study revealed that the estimation from observed sample agrees very well with
third order Jackknife method of estimation.",1205.4306v1
2019-01-14,Isometry groups of closed Lorentz 4-manifolds are Jordan,"We prove that for any closed Lorentz $4$-manifold $(M,g)$ the isometry group
$Isom(M,g)$ is Jordan. Namely, there exists a constant $C$ (depending on $M$
and $g$) such that any finite subgroup $\Gamma\leq Isom(M,g)$ has an abelian
subgroup $A\leq\Gamma$ satisfying $[\Gamma:A]\leq C$.",1901.04257v1
2019-12-17,"A Characterization of the Lorentz space $L(p,r)$ in terms of Orlicz type classes","We describe the Lorentz space $L(p, r), 0 < r < p, p > 1$, in terms of Orlicz
type classes of functions L . As a consequence of this result it follows that
Stein's characterization of the real functions on $R^n$ that are differentiable
at almost all the points in $R^n$, is equivalent to the earlier
characterization of those functions given by A. P. Calderon.",1912.08300v1
2020-08-24,An exact derivation of the Thomas precession rate using the Lorentz transformation,"Using the standard formalism of Lorentz transformation of the special theory
of relativity, we derive the exact expression of the Thomas precession rate for
an electron in a classical circular orbit around the nucleus of a hydrogen-like
atom.",2009.05393v1
2020-09-15,Decay estimates for Schrödinger heat semigroup with inverse square potential in Lorentz spaces,"Let $H:=-\Delta+V$ be a nonnegative Schr\""odinger operator on $L^2({\bf
R}^N)$, where $N\ge 2$ and $V$ is an inverse square potential. In this paper we
obtain sharp decay estimates of the operator norms of $e^{-tH}$ and $\nabla
e^{-tH}$ in Lorentz spaces.",2009.07001v1
2020-10-12,Polynomial bound for the localization length of Lorentz mirror model on the 1D cylinder,"We consider the Lorentz mirror model and the Manhattan model on the
even-width cylinder $\mathbb{Z} \times (\mathbb{Z}/2n\mathbb{Z})
=\{(x,y):x,y\in \mathbb{Z}, 1\leq y\leq 2n\}$. For both models, we show that
for large enough $n$, with high probability, any trajectory of light starting
from the section $x=0$ is contained in the region $|x|\leq O(n^{10})$.",2010.05900v1
2021-03-07,Lorentz and Gale-Ryser theorems on general measure spaces,"Based on the Gale-Ryser theorem for the existence of suitable
$(0,1)$-matrices for different partitions of a natural number, we revisit the
classical result of G. G. Lorentz regarding the characterization of a plane
measurable set, in terms of its cross sections, and extend it to general
measure spaces.",2103.04292v2
2021-08-19,Maxwell-Lorentz without self interactions: Conservation of energy and momentum,"Since a classical charged point particle radiates energy and momentum it is
argued that there must be a radiation reaction force. Here we present an action
for the Maxwell-Lorentz without self interactions model, where each particle
only responds to the fields of the other charged particles. The corresponding
stress-energy tensor automatically conserves energy and momentum in Minkowski
and other appropriate spacetimes.",2108.08644v1
2021-08-21,Nonuniqueness of solutions to the Euler equations with vorticity in a Lorentz space,"For the two dimensional Euler equations, a classical result by Yudovich
states that solutions are unique in the class of bounded vorticity; it is a
celebrated open problem whether this uniqueness result can be extended in other
integrability spaces. We prove in this note that such uniqueness theorem fails
in the class of vector fields $u$ with uniformly bounded kinetic energy and
vorticity in the Lorentz space $L^{1, \infty}$.",2108.09469v1
2021-08-31,Local large deviations for periodic infinite horizon Lorentz gases,"We prove local large deviations for the periodic infinite horizon Lorentz gas
viewed as a ${\mathbb Z}^d$-cover ($d=1,2$) of a dispersing billiard. In
addition to this specific example, we prove a general result for a class of
nonuniformly hyperbolic dynamical systems and observables associated with
central limit theorems with nonstandard normalisation.",2108.13748v2
2021-09-23,Nikolskii Type Inequalities for Entire Functions of Exponential Type in Lorentz Zygmund Spaces,"Nikolskii type inequalities for entire functions of exponential type on Rn
for the Lorentz Zygmund spaces are obtained. Some new limiting cases are
examined. Application to Besov type spaces of logarithmic smoothness is given.",2109.11239v2
2021-11-03,The Dirichlet problem for a class of Hessian quotient equations in Lorentz-Minkowski space $\mathbb{R}^{n+1}_{1}$,"In this paper, under suitable settings, we can obtain the existence and
uniqueness of solutions to a class of Hessian quotient equations with Dirichlet
boundary condition in Lorentz-Minkowski space $\mathbb{R}^{n+1}_{1}$, which can
be seen as a prescribed curvature problem and a continuous work of [12].",2111.02028v1
2021-11-05,Maximal and Calderon-Zygmund operators on the local variable Morrey-Lorentz spaces and some applications,"In this paper, we give the definition of local variable Morrey Lorentz spaces
which are a new class of functions. Also, we prove the boundedness of the Hardy
Littlewood maximal operator M and Calderon Zygmund operators T on these spaces.
Finally, we apply these results to the Bochner Riesz operator, identity
approximation and the Marcinkiewicz operator on these spaces.",2111.03726v1
2021-11-30,The Boltzmann-Grad Limit for the Lorentz Gas with a Poisson Distribution of Obstacles,"In this note, we propose a slightly different proof of Gallavotti's theorem
[""Statistical Mechanics: A Short Treatise"", Springer, 1999, pp. 48--55] on the
derivation of the linear Boltzmann equation for the Lorentz gas with a Poisson
distribution of obstacles in the Boltzmann-Grad limit.",2111.15270v1
2021-12-04,Cocompact imbedding theorem for functions of bounded variation into Lorentz spaces,"We show that the imbedding $\dot{BV}(\mathbb{R}^N)\hookrightarrow
L^{1^\ast,q}(\mathbb{R}^N)$, $q>1$ is cocompact with respect to group and the
profile decomposition for $\dot{BV}(\mathbb{R}^N)$. This paper extends the
cocompactness and profile decomposition for the critical space
$L^{1^\ast}(\mathbb{R}^N)$ to Lorentz spaces $L^{1^\ast,q}(\mathbb{R}^N)$,
$q>1$. A counterexample for $\dot{BV}(\mathbb{R}^N)\hookrightarrow
L^{1^\ast,1}(\mathbb{R}^N)$ not cocompact is given in the last section.",2112.02327v1
2022-02-05,Discrete Gravity with Local Lorentz Invariance,"A novel structure-preserving algorithm for general relativity in vacuum is
derived from a lattice gauge theoretic discretization of the tetradic Palatini
action. The resulting model of discrete gravity is demonstrated to preserve
local Lorentz invariance and symplectic structure.",2202.02486v2
2022-02-05,"Special Relativity, Einstein Velocity Addition, and Gyrogroups: An Introduction","In these notes we give an introductory unified treatment to the topics of
special relativity, Lorentz transformations and the Lorentz group, Einstein
velocitiy addition, and gyrogroups and gyrovector spaces. An effort has been
made to present the material in a manner that is accessible to non-specialists
and graduate students, and may even serve as the basis for a graduate course or
seminar.",2202.08204v1
2022-03-25,On homogeneous Hermite-Lorentz spaces of low dimension,"We classify irreducible homogeneous almost Hermite-Lorentz spaces of complex
dimension 3.",2203.13772v4
2022-05-27,Anisotropic Hardy-Sobolev inequality in mixed Lorentz spaces with applications to the axisymmetric Navier-Stokes equations,"In this paper, we establish several new anisotropic Hardy-Sobolev
inequalities in mixed Lebesgue spaces and mixed Lorentz spaces, which covers
many known corresponding results. As an application, this type of inequalities
allows us to generalize some regularity criteria of the 3D axisymmetric
Navier-Stokes equations.",2205.13893v1
2022-07-10,Lorentz Tests with Astrophysical Photons,"Astrophysical polarization measurements provide some of the strongest
constraints on the photon sector of the non-minimal Standard-Model Extension.
This paper reviews some recent results obtained by combining optical linear and
circular polarization data from a large number of astrophysical objects.",2207.04533v1
2022-07-31,Li-Yorke and Expansive Composition Operators on Lorentz Spaces,"In this paper, we investigate Li-Yorke composition operators and some of
their variations on Lorentz spaces. Further, we also study expansive
composition operators on these spaces. The work of the paper is essentially
based on the work in [1], [9], [11], and [13].",2208.00342v1
2022-10-01,Expansivity Property for Composition Operators on Orlicz -Lorentz Spaces,"In this paper, we investige the concept of expansivity for composition
operators on Orlicz-Lorentz spaces. We study necessary and sufficient
conditions for expansivity, positive expansivity and uniformly expansivity for
composition operators $C_{\tau}$ on $\mathbb{L}^{\varphi,h}(\mu)$. We extend
the of results of [15] into Orlicz-Lorentz spaces",2210.00333v1
2022-10-12,Lorentz-covariant nonlocal collision term for spin-1/2 particles,"We revisit the derivation of the nonlocal collision term in the Boltzmann
equation for spin-1/2 particles, using both the Wigner-function approach by de
Groot, van Leeuwen, and van Weert, and the Kadanoff-Baym equation in $T$-matrix
approximation. Contrary to previous calculations, our results maintain full
Lorentz covariance of the nonlocal collision term.",2210.06187v1
2022-12-17,Relations between Lorentz-Zygmund and Grand Lebesgue Spaces and norms,"We establish imbedding properties between Grand Lebesgue Spaces and
(generalized) Lorentz-Zygmund ones. We extend some known previous results
concerning imbedding theorems between Grand Lebesgue and classical
Lebesgue-Riesz spaces and we show the exactness of the obtained estimates.",2212.08938v2
2023-03-08,"Comment on ""Relativistic quantum oscillator model under the effects of the violation of Lorentz symmetry by an arbitrary fixed vector field'' by Faizuddin Ahmed","We obtain the correct expressions for the energy and normalized
eigenfunctions for a spin-zero relativistic quantum oscillator model under the
violation of Lorentz symmetry defined by an arbitrary constant vector field
$v^{\mu}$.",2303.05418v1
2023-11-30,Maximal exponent of the Lorentz cones,"We show that the maximal exponent (i.e., the minimum number of iterations
required for a primitive map to become strictly positive) of the n-dimensional
Lorentz cone is equal to n. As a byproduct, we show that the optimal exponent
in the quantum Wielandt inequality for qubit channels is equal to 3.",2311.18634v2
2023-12-06,Darboux transformations of spacelike curves in the Lorentz-Minkowski plane,"This paper concerns (Lorentz-)Darboux transformations in the
Lorentz-Minkowski plane $\mathbb{R}^{1,1}$. We use the Penrose diagram for
conformal compactification and show some unique properties of Darboux
transformations of spacelike curves in $\mathbb{R}^{1,1}$, especially with
regard to singularities and blowup. Finally, we make some comments on Darboux
transformation of type-changing curves.",2312.03363v1
2023-12-22,From the Lorentz invariant to the coframe form of $f(T)$ gravity,"It is shown that the Lorentz invariant $f(T)$ gravity, defined by the
coframe-connection-multiplier form of the Lagrangian, can be gauge-fixed to the
pure coframe form. After clarifying basic aspects of the problem in the
Lagrangian formalism, a more detailed analysis of this gauge equivalence is
given relying on the Dirac Hamiltonian approach.",2312.14603v1
2023-12-23,Global attraction to solitons for 2D Maxwell--Lorentz equations with spinning particle,"We consider the 2D Maxwell--Lorentz system which describes a rotating
particle coupled to the Maxwell field. The system admits stationary
soliton-type solutions. We prove the attraction to solitons for any finite
energy solution relying on the conservation of angular momentum.",2312.15284v1
2023-12-30,A Christ-Kiselev maximal theorem in quasi-Banach function lattices,"A Christ-Kiselev maximal theorem is proved for linear operators between
quasi-Banach function lattices satisfying certain lattice geometrical
conditions. The result is further explored for weighted Lorentz spaces,
classical Lorentz spaces, and Wiener amalgams of Lebesgue function and sequence
spaces. Extensions are made to K\""othe dual operators and to operators on
interpolation spaces of quasi-Banach function lattices. Several applications to
maximal Fourier operators are presented.",2401.00119v1
1994-05-02,Damped Lyman Alpha Systems vs. Cold + Hot Dark Matter,"Although the Cold + Hot Dark Matter (CHDM) cosmology provides perhaps the
best fit of any model to all the available data at the current epoch, CHDM
produces structure at relatively low redshifts and thus could be ruled out if
there were evidence for formation of massive objects at high redshifts. Damped
Ly$\alpha$ systems are abundant in quasar absorption spectra and thus provide
possibly the most significant evidence for early structure formation, and thus
perhaps the most stringent constraint on CHDM. Using the numbers of halos in
N-body simulations to normalize Press-Schechter estimates of the number
densities of protogalaxies as a function of redshift, we find that CHDM with
$\Omega_c/\Omega_\nu/\Omega_b = 0.6/0.3/0.1$ is compatible with the damped
Ly$\alpha$ data at $\le 2.5$, but that it is probably incompatible with the
limited $z>3$ damped Ly$\alpha$ data. The situation is uncertain because there
is very little data for $z>3$, and also it is unclear whether all damped
Ly$\alpha$ systems are associated with collapsed protogalaxies. The predictions
of CHDM are quite sensitive to the hot (neutrino) fraction, and we find that
$\Omega_c/\Omega_\nu/\Omega_b = 0.675/0.25/0.075$ is compatible even with the
$z>3$ data. This corresponds to lowering the neutrino mass from 6.8 to 5.7 eV,
for $H_0=50\kmsMpc$. In CHDM, the higher redshift damped Ly$\alpha$ systems are
predicted to have lower masses, which can be checked by measuring the velocity
widths of the associated metal line systems.",9405003v1
1995-03-24,High Redshift Lyman Limit and Damped Lyman-Alpha Absorbers,"We have obtained high signal:to:noise optical spectroscopy at 5\AA\
resolution of 27 quasars from the APM z$>$4 quasar survey. The spectra have
been analyzed to create new samples of high redshift Lyman-limit and damped
Lyman-$\alpha$ absorbers. These data have been combined with published data
sets in a study of the redshift evolution and the column density distribution
function for absorbers with $\log$N(HI)$\ge17.5$, over the redshift range 0.01
$<$ z $<$ 5. The main results are: \begin{itemize} \item Lyman limit systems:
The data are well fit by a power law $N(z) = N_0(1 + z)^{\gamma}$ for the
number density per unit redshift. For the first time intrinsic evolution is
detected in the product of the absorption cross-section and comoving spatial
number density for an $\Omega = 1$ Universe. We find $\gamma = 1.55$ ($\gamma =
0.5$ for no evolution) and $N_0 = 0.27$ with $>$99.7\% confidence limits for
$\gamma$ of 0.82 \& 2.37. \item Damped \lya systems: The APM QSOs provide a
substantial increase in the redshift path available for damped surveys for
$z>3$. Eleven candidate and three confirmed damped Ly$\alpha$ absorption
systems, have been identified in the APM QSO spectra covering the redshift
range $2.8\le z \le 4.4$ (11 with $z>3.5$). Combining the APM survey confirmed
and candidate damped \lya absorbers with previous surveys, we find evidence for
a turnover at z$\sim$3 or a flattening at z$\sim$2 in the cosmological mass
density of neutral gas, $\Omega_g$. \end{itemize} The Lyman limit survey
results are published in Storrie-Lombardi, et~al., 1994, ApJ, 427, L13. Here we
describe the results for the DLA population of absorbers.",9503089v1
1997-05-15,Cosmological Constraints from High-Redshift Damped Lyman-Alpha Systems,"Any viable cosmological model must produce enough structure at early epochs
to explain the amount of gas associated with high-redshift damped Ly$\alpha$
systems. We study the evolution of damped Ly$\alpha$ systems at redshifts $z\ge
2$ in cold dark matter (CDM) and cold+hot dark matter (CDM+HDM) models using
both N-body and hydrodynamic simulations. Our approach incorporates the effects
of gas dynamics, and we find that all earlier estimates which assumed that all
the baryons in dark matter halos would contribute to damped Ly$\alpha$
absorption have overestimated the column density distribution $f(N)$ and the
fraction of neutral dense gas $\Omega_g$ in damped Ly$\alpha$ systems. The
differences are driven by ionization of hydrogen in the outskirts of galactic
halos and by gaseous dissipation near the halo centers, and they tend to
exacerbate the problem of late galaxy formation in CDM+HDM models. We only
include systems up to the highest observed column density $N\sim 10^{21.8}$
cm$^{-2}$ in the estimation of $\Omega_g$ for a fair comparison with data. If
the observed $f(N)$ and $\Omega_g$ inferred from a small number of confirmed
and candidate absorbers are robust, the amount of gas in damped Ly$\alpha$
systems at high redshifts in the $\Omega_\nu=0.2$ CDM+HDM model falls well
below the observations.",9705113v1
2001-01-03,Galactic Chemical Abundances at z>3 I: First Results from the Echellette Spectrograph and Imager,"We present the first results from an ongoing survey to discover and measure
the metallicity of z>3 damped Lya systems with the Echellette Spectrograph and
Imager (ESI) on the Keck II telescope. Our motivation arises from a recent
study on the damped Lya systems suggesting only mild evolution in the cosmic
metallicity from z~2 to 4. The Echellette Spectrograph and Imager, which
provides two complementary spectroscopic modes, is the ideal instrument for a
z>3 damped Lya survey. We describe our observing strategy and report on the
discovery and analysis of 5 new z>3 damped Lya systems acquired in a single
night of observing. These observations further support the principal
conclusions of the previous study: (1) the cosmic metallicity in neutral gas
inferred from the damped Lya systems does not evolve significantly from z~2 to
4; (2) the unweighted metallicity exhibits a statistically significant decrease
with increasing redshift; and (3) not a single damped Lya system has a
metallicity below [Fe/H]=-3. We discuss the implications of these results and
comment on recent theoretical studies which attempt to explain the
observations.",0101029v1
2002-01-17,Self-shielding Effects on the Column Density Distribution of Damped Lyman Alpha Systems,"We calculate the column density distribution of damped Lyman alpha systems,
modeled as spherical isothermal gaseous halos ionized by the external cosmic
background. The effects of self-shielding introduce a hump in this
distribution, at a column density N_{HI} \sim 1.6x10^{17} X^{-1} cm^{-2}, where
X is the neutral fraction at the radius where self-shielding starts being
important. The most recent compilation of the column density distribution by
Storrie-Lombardi & Wolfe shows marginal evidence for the detection of this
feature due to self-shielding, suggesting a value X \sim 10^{-3}. Assuming a
photoionization rate \Gamma \sim 10^{-12} s^{-1} from the external ionizing
background, the radius where self-shielding occurs is inferred to be about
3.8kpc. If damped Lyman alpha systems consist of a clumpy medium, this should
be interpreted as the typical size of the gas clumps in the region where they
become self-shielding. Clumps of this size with typical column densities N_H
\sim 3x10^{20} cm^{-2} would be in hydrostatic equilibrium at the
characteristic photoionization temperature \sim 10^4 K if they do not contain
dark matter. Since this size is similar to the overall radius of damped \lya
systems in Cold Dark Matter models, where all halos are assumed to contain
similar gas clouds producing damped absorbers, this suggests that the gas in
damped absorbers is in fact not highly clumped.",0201275v2
2002-04-30,Two-phase equilibrium and molecular hydrogen formation in damped Lyman-alpha systems,"Molecular hydrogen is quite underabundant in damped Lyman-alpha systems at
high redshift, when compared to the interstellar medium near the Sun. This has
been interpreted as implying that the gas in damped Lyman-alpha systems is
warm. like the nearby neutral intercloud medium, rather than cool, as in the
clouds which give rise to most H I absorption in the Milky Way. Other lines of
evidence suggest that the gas in damped Lyman-alpha systems -- in whole or part
-- is actually cool; spectroscopy of neutral and ionized carbon, discussed
here, shows that the damped Lyman-alpha systems observed at lower redshift z
$<$ 2.3 are largely cool, while those seen at z $>$ 2.8 are warm (though not
devoid of H2). To interpret the observations of carbon and hydrogen we
constructed detailed numerical models of H2 formation under the conditions of
two-phase thermal equilibrium, like those which account for conditions near the
Sun, but with varying metallicity, dust-gas ratio, $etc$. We find that the low
metallicity of damped Lyman-alpha systems is enough to suppress H2 formation by
many orders of magnitude even in cool diffuse clouds, as long as the ambient
optical/uv radiation field is not too small. For very low metallicity and under
the most diffuse conditions, H2 formation will be dominated by slow gas-phase
processes not involving grains, and a minimum molecular fraction in the range
$10^{-8}-10^{-7}$ is expected.",0204515v1
2003-05-12,Ordinary and Viscosity-Damped MHD Turbulence,"We compare the properties of ordinary strong magnetohydrodynamic (MHD)
turbulence in a strongly magnetized medium with the recently discovered
viscosity-damped regime. We focus on energy spectra, anisotropy, and
intermittency. Our most surprising conclusion is that in ordinary strong MHD
turbulence the velocity and magnetic fields show different high-order structure
function scalings. Moreover this scaling depends on whether the intermittency
is viewed in a global or local system of reference. This reconciles seemingly
contradictory earlier results. On the other hand, the intermittency scaling for
viscosity-damped turbulence is very different, and difficult to understand in
terms of the usual phenomenological models for intermittency in turbulence. Our
remaining results are in reasonable agreement with expectations. First, we find
that our high resolution simulations for ordinary MHD turbulence show that the
energy spectra are {\it compatible} with a Kolmogorov spectrum, while
viscosity-damped turbulence shows a shallow $k^{-1}$ spectrum for the magnetic
fluctuations. Second, a new numerical technique confirms that ordinary MHD
turbulence exhibits Goldreich-Sridhar type anisotropy, while viscosity-damped
MHD turbulence shows extremely anisotropic eddy structures. Finally, we show
that many properties of incompressible turbulence for both the ordinary and
viscosity-damped regimes carry over to the case of compressible turbulence.",0305212v2
2003-09-17,Observational Tests of Damping by Resonant Absorption in Coronal Loop Oscillations,"One of the proposed damping mechanisms of coronal (transverse) loop
oscillations in the kink-mode is resonant absorption as a result of the Alfven
speed variation at the outer boundary of coronal loops. Analytical expressions
for the period and damping time exist for loop models with thin non-uniform
boundaries. Here we measure the thickness of the non-uniform layer in
oscillating loops for 11 events, by forward-fitting of the cross-sectional
density profile and line-of-sight integration to the cross-sectional fluxes
observed with TRACE 171 A. This way we model the internal and external electron
density of the coronal plasma in oscillating loops. This allows us to test the
theoretically predicted damping rates for thin boundaries as function of the
density ratio. We find that the density ratio predicted by the damping time is
higher than the density ratio estimated from the background fluxes. The lower
densities modeled from the background fluxes are likely to be a consequence of
the neglected hotter plasma that is not detected with the TRACE 171 A filter.
Taking these correction into account, resonant absorption predicts damping
times of kink-mode oscillations that are commensurable with the observed ones
and provides a new diagnostic of the density contrast of oscillating loops.",0309470v1
2005-03-01,Metal Abundances in a Damped Lyman-alpha System Along Two Lines of Sight at z=0.93,"We study metal abundances in the z=0.9313 damped Lya system observed in the
two lines-of-sight, A and B, toward the gravitationally-lensed double QSO
HE0512-3329. Spatially resolved STIS spectra constrain the neutral-gas column
density to be LogN(HI)=20.5 in both Aand B. UVES spectra (spectral resolution
FWHM=9.8 km/s) show, in contrast, significant line-of-sight differences in the
column densities of MnII and FeII; these are not due to observational
systematics. We find that [Mn/H]=-1.44 and [Fe/H]=-1.52 in damped Lya system A,
while [Mn/H]=-0.98 and [Fe/H]>-1.32, and possibly as high as [Fe/H] approx. -1
in damped Lya system B. A careful assessment of possible systematic errors
leads us to conclude that these transverse differences are significant at a 5
sigma level or greater. Although nucleosynthesis effects may also be at play,
we favor differential dust-depletion as the main mechanism producing the
observed abundance gradient. The transverse separation is 5 kpc at the redshift
of the absorber, which is also likely to be the lensing galaxy. The derived
abundances therefore probe two opposite sides of a single galaxy hosting both
damped Lya systems. This is the first time firm abundance constraints have been
obtained for a single damped system probed by two lines-of-sight. The
significance of this finding for the cosmic evolution of metals is discussed.",0503026v1
2000-08-26,Adsorbate aggregation and relaxation of low-frequency vibrations,"We present a study of resonant vibrational coupling between adsorbates and an
elastic substrate at low macroscopic coverages. In the first part of the paper
we consider the situation when adsorbates form aggregates with high local
coverage. Based upon our previously published theory, we derive formulas
describing the damping rate of adsorbate vibrations for two cases of such
aggregation: (i) adsorbates attached to step edges and (ii) adsorbates forming
two-dimensional islands. We have shown that damping is governed by local
coverage. Particularly, for a wide range of resonant frequencies, the damping
rate of adsorbates forming well separated islands is described by the damping
rate formula for a periodic overlayer with the coverage equal to the local
coverage in the island. The second part of the paper is devoted to facilitating
the evaluation of damping rates for a disordered overlayer. The formula
describing the damping rate involves the parameter $\beta$ which is related to
the local density of phonon states at the substrate surface and does not allow
a closed-form representation. For substrates of isotropic and cubic symmetries,
we have developed a good analytical approximation to this parameter. For a vast
majority of cubic substrates the difference between the analytical
approximation and numerical calculation does not exceed 4%.",0008389v1
2004-10-26,Mean-field treatment of the damping of the oscillations of a 1D Bose gas in an optical lattice,"We present a theoretical treatment of the surprisingly large damping observed
recently in one-dimensional Bose-Einstein atomic condensates in optical
lattices. We show that time-dependent Hartree-Fock-Bogoliubov (HFB)
calculations can describe qualitatively the main features of the damping
observed over a range of lattice depths. We also derive a formula of the
fluctuation-dissipation type for the damping, based on a picture in which the
coherent motion of the condensate atoms is disrupted as they try to flow
through the random local potential created by the irregular motion of
noncondensate atoms. We expect this irregular motion to result from the
well-known dynamical instability exhibited by the mean-field theory for these
systems. When parameters for the characteristic strength and correlation times
of the fluctuations, obtained from the HFB calculations, are substituted in the
damping formula, we find very good agreement with the experimentally-observed
damping, as long as the lattice is shallow enough for the fraction of atoms in
the Mott insulator phase to be negligible. We also include, for completeness,
the results of other calculations based on the Gutzwiller ansatz, which appear
to work better for the deeper lattices.",0410677v4
2006-02-09,Magnetization damping in polycrystalline Co ultra-thin films: Evidence for non-local effects,"The magnetic properties and magnetization dynamics of polycrystalline
ultra-thin Co layers were investigated using a broadband ferromagnetic
resonance (FMR) technique at room temperature. A variable thickness (1 nm $\leq
t \leq$ 10 nm) Co layer is sandwiched between 10 nm thick Cu layers (10 nm Cu|
t Co|10 nm Cu), while materials in contact with the Cu outer interfaces are
varied to determine their influence on the magnetization damping. The resonance
field and the linewidth were studied for in-plane magnetic fields in field
swept experiments at a fixed frequency, from 4 to 25 GHz. The Co layers have a
lower magnetization density than the bulk, and an interface contribution to the
magnetic anisotropy normal to the film plane. The Gilbert damping, as
determined from the frequency dependence of the linewidth, increases with
decreasing Co layer thickness for films with outer Pt layers. This enhancement
is not observed in structures without Pt layers. The result can be understood
in terms of a non-local contribution to the damping due to spin pumping from Co
through the Cu layer and spin relaxation in Pt layers. Pt layers just 1.5 nm
thick are found to be sufficient to enhance the damping and thus act as
efficient ""spin-sinks"". In structures with Pt outer layers, this non-local
contribution to the damping becomes predominant when the Co layer is thinner
than 4 nm.",0602243v2
1998-10-16,Fermion Damping in a Fermion-Scalar Plasma,"In this article we study the dynamics of fermions in a fermion-scalar plasma.
We begin by obtaining the effective in-medium Dirac equation in real time which
is fully renormalized and causal and leads to the initial value problem. For a
heavy scalar we find the novel result that the decay of the scalar into fermion
pairs in the medium leads to damping of the fermionic excitations and their
in-medium propagation as quasiparticles. That is, the fermions acquire a width
due to the decay of the heavier scalar in the medium. We find the damping rate
to lowest order in the Yukawa coupling for arbitrary values of scalar and
fermion masses, temperature and fermion momentum. An all-order expression for
the damping rate in terms of the exact quasiparticle wave functions is
established. A kinetic Boltzmann approach to the relaxation of the fermionic
distribution function confirms the damping of fermionic excitations as a
consequence of the induced decay of heavy scalars in the medium. A
linearization of the Boltzmann equation near equilibrium clearly displays the
relationship between the damping rate of fermionic mean fields and the fermion
interaction rate to lowest order in the Yukawa coupling directly in real time.",9810393v2
2006-01-06,Wave energy localization by self-focusing in large molecular structures: a damped stochastic discrete nonlinear Schroedinger equation model,"Wave self-focusing in molecular systems subject to thermal effects, such as
thin molecular films and long biomolecules, can be modeled by stochastic
versions of the Discrete Self-Trapping equation of Eilbeck, Lomdahl and Scott,
and this can be approximated by continuum limits in the form of stochastic
nonlinear Schroedinger equations.
  Previous studies directed at the SNLS approximations have indicated that the
self-focusing of wave energy to highly localized states can be inhibited by
phase noise (modeling thermal effects) and can be restored by phase damping
(modeling heat radiation).
  We show that the continuum limit is probably ill-posed in the presence of
spatially uncorrelated noise, at least with little or no damping, so that
discrete models need to be addressed directly. Also, as has been noted by other
authors, omission of damping produces highly unphysical results.
  Numerical results are presented for the first time for the discrete models
including the highly nonlinear damping term, and new numerical methods are
introduced for this purpose. Previous conjectures are in general confirmed, and
the damping is shown to strongly stabilize the highly localized states of the
discrete models. It appears that the previously noted inhibition of nonlinear
wave phenomena by noise is an artifact of modeling that includes the effects of
heat, but not of heat loss.",0601017v1
2007-11-15,Effect of the steady flow on spatial damping of small-amplitude prominence oscillations,"Aims. Taking account of steady flow in solar prominences, we study its
effects on spatial damping of small-amplitude non-adiabatic magnetoacoustic
waves in a homogeneous, isothermal, and unbounded prominence plasma. Methods.
We model the typical feature of observed damped oscillatory motion in
prominences, removing the adiabaticity assumption through thermal conduction,
radiation and heating. Invoking steady flow in MHD equations, we linearise them
under small-amplitude approximation and obtain a new general dispersion
relation for linear non-adiabatic magnetoacoustic waves in prominences Results.
The presence of steady flow breaks the symmetry of forward and backward
propagating MHD wave modes in prominences. The steady flow has dramatic
influence on the propagation and damping of magnetoacoustic and thermal waves.
Depending upon the direction and strength of flow the magnetoacoustic and
thermal modes can show both the features of wave amplification and damping. At
the wave period of 5 min where the photospheric power is maximum, the slow mode
shows wave amplification. However, in the absence of steady flow the slow mode
wave shows damping. Conclusions. For the wave period between 5 min and 15 min,
the amplification length for slow mode, in the case of prominence regime 1.1,
varies between 3.4*10^11 m to 2*10^12 m. Dramatic influence of steady flow on
small-amplitude prominence oscillations is likely to play an important role in
both wave detection and prominence seismology.",0711.2353v1
2008-02-07,Cascade and Damping of Alfvén-Cyclotron Fluctuations: Application to Solar Wind Turbulence Spectrum,"With the diffusion approximation, we study the cascade and damping of
Alfv\'{e}n-cyclotron fluctuations in solar plasmas numerically. Motivated by
wave-wave couplings and nonlinear effects, we test several forms of the
diffusion tensor. For a general locally anisotropic and inhomogeneous diffusion
tensor in the wave vector space, the turbulence spectrum in the inertial range
can be fitted with power-laws with the power-law index varying with the wave
propagation direction. For several locally isotropic but inhomogeneous
diffusion coefficients, the steady-state turbulence spectra are nearly
isotropic in the absence of damping and can be fitted by a single power-law
function. However, the energy flux is strongly polarized due to the
inhomogeneity that leads to an anisotropic cascade. Including the anisotropic
thermal damping, the turbulence spectrum cuts off at the wave numbers, where
the damping rates become comparable to the cascade rates. The combined
anisotropic effects of cascade and damping make this cutoff wave number
dependent on the wave propagation direction, and the propagation direction
integrated turbulence spectrum resembles a broken power-law, which cuts off at
the maximum of the cutoff wave numbers or the $^4$He cyclotron frequency.
Taking into account the Doppler effects, the model can naturally reproduce the
broken power-law wave spectra observed in the solar wind and predicts that a
higher break frequency is aways accompanied with a greater spectral index
change that may be caused by the increase of the Alfv\'{e}n Mach number, the
reciprocal of the plasma beta, and/or the angle between the solar wind velocity
and the mean magnetic field. These predictions can be tested by future
observations.",0802.0910v1
2011-04-13,Evolution of inclined planets in three-dimensional radiative discs,"While planets in the solar system only have a low inclination with respect to
the ecliptic there is mounting evidence that in extrasolar systems the
inclination can be very high, at least for close-in planets. One process to
alter the inclination of a planet is through planet-disc interactions. Recent
simulations considering radiative transport have shown that the evolution of
migration and eccentricity can strongly depend on the thermodynamic state of
the disc. We extend previous studies to investigate the planet-disc
interactions of fixed and moving planets on inclined and eccentric orbits. We
also analyse the effect of the disc's thermodynamic properties on the orbital
evolution of embedded planets in detail. The protoplanetary disc is modelled as
a viscous gas where the internally produced dissipation is transported by
radiation. For locally isothermal discs, we confirm previous results and find
inclination damping and inward migration for planetary cores. For low
inclinations i < 2 H/r, the damping is exponential, while di/dt is proportional
to i^-2 for larger i. For radiative discs, the planetary migration is very
limited, as long as their inclination exceeds a certain threshold. If the
inclination is damped below this threshold, planetary cores with a mass up to
approximately 33 Earth masses start to migrate outwards, while larger cores
migrate inwards right from the start. The inclination is damped for all
analysed planet masses. In a viscous disc an initial inclination of embedded
planets will be damped for all planet masses. This damping occurs on timescales
that are shorter than the migration time. If the inclination lies beneath a
certain threshold, the outward migration in radiative discs is not handicapped.
Outward migration is strongest for circular and non-inclined orbits.",1104.2408v1
2011-07-12,Mode conversion of radiatively damped magnetogravity waves in the solar chromosphere,"Modelling of adiabatic gravity wave propagation in the solar atmosphere
showed that mode conversion to field guided acoustic waves or Alfv\'en waves
was possible in the presence of highly inclined magnetic fields. This work aims
to extend the previous adiabatic study, exploring the consequences of radiative
damping on the propagation and mode conversion of gravity waves in the solar
atmosphere. We model gravity waves in a VAL-C atmosphere, subject to a uniform,
and arbitrarily orientated magnetic field, using the Newton cooling
approximation for radiatively damped propagation. The results indicate that the
mode conversion pathways identified in the adiabatic study are maintained in
the presence of damping. The wave energy fluxes are highly sensitive to the
form of the height dependence of the radiative damping time. While simulations
starting from 0.2 Mm result in modest flux attenuation compared to the
adiabatic results, short damping times expected in the low photosphere
effectively suppress gravity waves in simulations starting at the base of the
photosphere. It is difficult to reconcile our results and observations of
propagating gravity waves with significant energy flux at photospheric heights
unless they are generated in situ, and even then, why they are observed to be
propagating as low as 70 km where gravity waves should be radiatively
overdamped.",1107.2208v1
2014-04-01,Stellar dynamics in gas: The role of gas damping,"In this paper, we consider how gas damping affects the dynamical evolution of
gas-embedded star clusters. Using a simple three-component (i.e. one gas and
two stellar components) model, we compare the rates of mass segregation due to
two-body relaxation, accretion from the interstellar medium, and gas dynamical
friction in both the supersonic and subsonic regimes. Using observational data
in the literature, we apply our analytic predictions to two different
astrophysical environments, namely galactic nuclei and young open star
clusters. Our analytic results are then tested using numerical simulations
performed with the NBSymple code, modified by an additional deceleration term
to model the damping effects of the gas.
  The results of our simulations are in reasonable agreement with our analytic
predictions, and demonstrate that gas damping can significantly accelerate the
rate of mass segregation. A stable state of approximate energy equilibrium
cannot be achieved in our model if gas damping is present, even if Spitzer's
Criterion is satisfied. This instability drives the continued dynamical
decoupling and subsequent ejection (and/or collisions) of the more massive
population. Unlike two-body relaxation, gas damping causes overall cluster
contraction, reducing both the core and half-mass radii. If the cluster is mass
segregated (and/or the gas density is highest at the cluster centre), the
latter contracts faster than the former, accelerating the rate of core
collapse.",1404.0379v1
2014-04-26,Landau damping effects on dust-acoustic solitary waves in a dusty negative-ion plasma,"The nonlinear theory of dust-acoustic waves (DAWs) with Landau damping is
studied in an unmagnetized dusty negative-ion plasma in the extreme conditions
when the free electrons are absent. The cold massive charged dusts are
described by fluid equations, whereas the two-species of ions (positive and
negative) are described by the kinetic Vlasov equations. A Korteweg de-Vries
(KdV) equation with Landau damping, governing the dynamics of weakly nonlinear
and weakly dispersive DAWs, is derived following Ott and Sudan [Phys. Fluids
{\bf 12}, 2388 (1969)]. It is shown that for some typical laboratory and space
plasmas, the Landau damping (and the nonlinear) effects are more pronounced
than the finite Debye length (dispersive) effects for which the KdV soliton
theory is not applicable to DAWs in dusty pair-ion plasmas. The properties of
the linear phase velocity, solitary wave amplitudes (in presence and absence of
the Landau damping) as well as the Landau damping rate are studied with the
effects of the positive ion to dust density ratio $(\mu_{pd})$ as well as the
ratios of positive to negative ion temperatures $(\sigma)$ and masses $(m)$.",1404.6623v3
2015-03-31,Damping of Confined Excitations Modes of 1D Condensates in an Optical Lattice,"We study the damping of the collective excitations of Bose-Einstein
condensates in a harmonic trap potential loaded in an optical lattice. In the
presence of a confining potential the system is non-homogeneous and the
collective excitations are characterized by a set of discrete confined
phonon-like excitations. We derive a general convenient analytical description
for the damping rate, which takes into account, the trapping potential and the
optical lattice, for the Landau and Beliaev processes at any temperature, $T$.
At high temperature or weak spatial confinement, we show that both mechanisms
display linear dependence on $T$. In the quantum limit, we found that the
Landau damping is exponentially suppressed at low temperatures and the total
damping is independent of $T$. Our theoretical predictions for the damping rate
under thermal regime is in completely correspondence with the experimental
values reported for 1D condensate of sodium atoms. We show that the laser
intensity can tune the collision process, allowing a \textit{resonant effect}
for the condensate lifetime. Also, we study the influence of the attractive or
repulsive non-linear terms on the decay rate of the collective excitations. A
general expression of the renormalized Goldstone frequency has been obtained as
a function of the 1D non-linear self-interaction parameter, laser intensity and
temperature.",1503.08884v2
2015-08-06,On the spatial scales of wave heating in the solar chromosphere,"Dissipation of magnetohydrodynamic (MHD) wave energy has been proposed as a
viable heating mechanism in the solar chromospheric plasma. Here, we use a
simplified one-dimensional model of the chromosphere to theoretically
investigate the physical processes and the spatial scales that are required for
the efficient dissipation of Alfv\'en waves and slow magnetoacoustic waves. We
consider the governing equations for a partially ionized hydrogen-helium plasma
in the single-fluid MHD approximation and include realistic wave damping
mechanisms that may operate in the chromosphere, namely Ohmic and ambipolar
magnetic diffusion, viscosity, thermal conduction, and radiative losses. We
perform an analytic local study in the limit of small amplitudes to
approximately derive the lengthscales for critical damping and efficient
dissipation of MHD wave energy. We find that the critical dissipation
lengthscale for Alfv\'en waves depends strongly on the magnetic field strength
and ranges from 10~m to 1~km for realistic field strengths. The damping of
Alfv\'en waves is dominated by Ohmic diffusion for weak magnetic field and low
heights in the chromosphere, and by ambipolar diffusion for strong magnetic
field and medium/large heights in the chromosphere. Conversely, the damping of
slow magnetoacoustic waves is less efficient, and spatial scales shorter than
10~m are required for critical damping. Thermal conduction and viscosity govern
the damping of slow magnetoacoustic waves and play an equally important role at
all heights. These results indicate that the spatial scales at which strong
wave heating may work in the chromosphere are currently unresolved by
observations.",1508.01497v1
2015-11-11,A statistical study of decaying kink oscillations detected using SDO/AIA,"Despite intensive studies of kink oscillations of coronal loops in the last
decade, a large scale statistically significant investigation of the
oscillation parameters has not been made using data from the Solar Dynamics
Observatory (SDO).
  We carry out a statistical study of kink oscillations using Extreme
Ultra-Violet (EUV) imaging data from a previously compiled catalogue.
  We analysed 58 kink oscillation events observed by the Atmospheric Imaging
Assembly (AIA) onboard SDO during its first four years of operation
(2010-2014). Parameters of the oscillations, including the initial apparent
amplitude, period, length of the oscillating loop, and damping are studied for
120 individual loop oscillations.
  Analysis of the initial loop displacement and oscillation amplitude leads to
the conclusion that the initial loop displacement prescribes the initial
amplitude of oscillation in general. The period is found to scale with the loop
length, and a linear fit of the data cloud gives a kink speed of Ck
=(1330+/-50) km s-1 . The main body of the data corresponds to kink speeds in
the range Ck =(800-3300) km s-1. Measurements of 52 exponential damping times
were made, and it was noted that at least 22 of the damping profiles may be
better approximated by a combination of non-exponential and exponential
profiles, rather than a purely exponential damping envelope. There are an
additional 10 cases where the profile appears to be purely non-exponential, and
no damping time was measured. A scaling of the exponential damping time with
the period is found, following the previously established linear scaling
between these two parameters.",1511.03558v1
2016-02-19,A systematic study of magnetodynamic properties at finite temperatures in doped permalloy from first principles calculations,"By means of first principles calculations, we have systematically
investigated how the magnetodynamic properties Gilbert damping, magnetization
and exchange stiffness are affected when permalloy (Py)
(Fe$_{0.19}$Ni$_{0.81}$) is doped with 4d or 5d transition metal impurities. We
find that the trends in the Gilbert damping can be understood from relatively
few basic parameters such as the density of states at the Fermi level, the
spin-orbit coupling and the impurity concentration. % The temperature
dependence of the Gilbert damping is found to be very weak which we relate to
the lack of intraband transitions in alloys. % Doping with $4d$ elements has no
major impact on the studied Gilbert damping, apart from diluting the host.
However, the $5d$ elements have a profound effect on the damping and allows it
to be tuned over a large interval while maintaining the magnetization and
exchange stiffness. % As regards spin stiffness, doping with early transition
metals results in considerable softening, whereas late transition metals have a
minor impact. % Our result agree well with earlier calculations where
available. In comparison to experiments, the computed Gilbert damping appears
slightly underestimated while the spin stiffness show good general agreement.",1602.06201v2
2016-03-01,A comparative study of protocols for secure quantum communication under noisy environment: single-qubit-based protocols versus entangled-state-based protocols,"The effect of noise on various protocols of secure quantum communication has
been studied. Specifically, we have investigated the effect of amplitude
damping, phase damping, squeezed generalized amplitude damping, Pauli type as
well as various collective noise models on the protocols of quantum key
distribution, quantum key agreement,quantum secure direct quantum communication
and quantum dialogue. From each type of protocol of secure quantum
communication, we have chosen two protocols for our comparative study; one
based on single qubit states and the other one on entangled states. The
comparative study reported here has revealed that single-qubit-based schemes
are generally found to perform better in the presence of amplitude damping,
phase damping, squeezed generalized amplitude damping noises, while
entanglement-based protocols turn out to be preferable in the presence of
collective noises. It is also observed that the effect of noise entirely
depends upon the number of rounds of quantum communication involved in a scheme
of quantum communication. Further, it is observed that squeezing, a completely
quantum mechanical resource present in the squeezed generalized amplitude
channel, can be used in a beneficial way as it may yield higher fidelity
compared to the corresponding zero squeezing case.",1603.00178v1
2016-11-17,A stable partitioned FSI algorithm for rigid bodies and incompressible flow. Part I: Model problem analysis,"A stable partitioned algorithm is developed for fluid-structure interaction
(FSI) problems involving viscous incompressible flow and rigid bodies. This
{\em added-mass partitioned} (AMP) algorithm remains stable, without
sub-iterations, for light and even zero mass rigid bodies when added-mass and
viscous added-damping effects are large. The scheme is based on a generalized
Robin interface condition for the fluid pressure that includes terms involving
the linear acceleration and angular acceleration of the rigid body. Added-mass
effects are handled in the Robin condition by inclusion of a boundary integral
term that depends on the pressure. Added-damping effects due to the viscous
shear forces on the body are treated by inclusion of added-damping tensors that
are derived through a linearization of the integrals defining the force and
torque. Added-damping effects may be important at low Reynolds number, or, for
example, in the case of a rotating cylinder or rotating sphere when the
rotational moments of inertia are small. In this first part of a two-part
series, the properties of the AMP scheme are motivated and evaluated through
the development and analysis of some model problems. The analysis shows when
and why the traditional partitioned scheme becomes unstable due to either
added-mass or added-damping effects. The analysis also identifies the proper
form of the added-damping which depends on the discrete time-step and the
grid-spacing normal to the rigid body. The results of the analysis are
confirmed with numerical simulations that also demonstrate a second-order
accurate implementation of the AMP scheme.",1611.05711v1
2017-01-30,Torsional Alfvén resonances as an efficient damping mechanism for non-radial oscillations in red giant stars,"Stars are self-gravitating fluids in which pressure, buoyancy, rotation and
magnetic fields provide the restoring forces for global modes of oscillation.
Pressure and buoyancy energetically dominate, while rotation and magnetism are
generally assumed to be weak perturbations and often ignored. However,
observations of anomalously weak dipole mode amplitudes in red giant stars
suggest that a substantial fraction of these are subject to an additional
source of damping localised to their core region, with indirect evidence
pointing to the role of a deeply buried magnetic field. It is also known that
in many instances the gravity-mode character of affected modes is preserved,
but so far no effective damping mechanism has been proposed that accommodates
this aspect. Here we present such a mechanism, which damps the oscillations of
stars harbouring magnetised cores via resonant interactions with standing
Alfv\'en modes of high harmonic index. The damping rates produced by this
mechanism are quantitatively on par with those associated with turbulent
convection, and in the range required to explain observations, for realistic
stellar models and magnetic field strengths. Our results suggest that magnetic
fields can provide an efficient means of damping stellar oscillations without
needing to disrupt the internal structure of the modes, and lay the groundwork
for an extension of the theory of global stellar oscillations that incorporates
these effects.",1701.08771v1
2018-05-29,Basic microscopic plasma physics from N-body mechanics,"Computing is not understanding. This is exemplified by the multiple and
discordant interpretations of Landau damping still present after seventy years.
For long deemed impossible, the mechanical N-body description of this damping,
not only enables its rigorous and simple calculation, but makes unequivocal and
intuitive its interpretation as the synchronization of almost resonant passing
particles. This synchronization justifies mechanically why a single formula
applies to both Landau growth and damping. As to the electrostatic potential,
the phase mixing of many beam modes produces Landau damping, but it is
unexpectedly essential for Landau growth too. Moreover, collisions play an
essential role in collisionless plasmas. In particular, Debye shielding results
from a cooperative dynamical self-organization process, where ""collisional""
deflections due to a given electron diminish the apparent number of charges
about it. The finite value of exponentiation rates due to collisions is crucial
for the equivalent of the van Kampen phase mixing to occur in the N-body
system. The N-body approach incorporates spontaneous emission naturally, whose
compound effect with Landau damping drives a thermalization of Langmuir waves.
O'Neil's damping with trapping typical of initially large enough Langmuir waves
results from a phase transition. As to collisional transport, there is a smooth
connection between impact parameters where the two-body Rutherford picture is
correct, and those where a collective description is mandatory. The N-body
approach reveals two important features of the Vlasovian limit: it is singular
and it corresponds to a renormalized description of the actual N-body dynamics.",1805.11408v2
2013-09-23,Phonon-mediated damping of mechanical vibrations in a finite atomic chain coupled to an outer environment,"We study phonon-mediated damping of mechanical vibrations in a finite
quantum-mechanical atomic-chain model. Our study is motivated by the quest to
understand the quality factors (Q) of nanomechanical resonators and
nanoelectromechanical systems (NEMS), as well as actual experiments with
suspended atomic chains and molecular junctions. We consider a finite atomic
chain which is coupled to a zero-temperature outer environment, modeled as two
additional semi-infinite chains, thus inducing ""clamping-losses"". Weak coupling
to the outer environment ensures that the clamping losses are small, and that
the initially discrete nature of the phonon spectrum is approximately
maintained. We then consider a phonon damping process known as ""Landau-Rumer
damping"", where phonons in the excited mode of vibration decay into other modes
through anharmonic phonon-phonon interaction. The approximately discrete nature
of the phonon spectrum leads to sharp nonmonotonic changes in Q as parameters
are varied, and to the appearance of resonances in the damping. The latter
correspond to the existence of decay processes where the participating phonons
approximately conserve energy. We explore means to control the damping by
changing either the number of atoms in the chains or the ratio between the
longitudinal and transverse speeds of sound, thereby suggesting future
experiments to observe this resonance-like behavior.",1309.5772v1
2020-04-09,Magnetic Damping in Epitaxial Fe Alloyed with Vanadium and Aluminum,"To develop low-moment, low-damping metallic ferromagnets for power-efficient
spintronic devices, it is crucial to understand how magnetic relaxation is
impacted by the addition of nonmagnetic elements. Here, we compare magnetic
relaxation in epitaxial Fe films alloyed with light nonmagnetic elements of V
and Al. FeV alloys exhibit lower intrinsic damping compared to pure Fe, reduced
by nearly a factor of 2, whereas damping in FeAl alloys increases with Al
content. Our experimental and computational results indicate that reducing the
density of states at the Fermi level, rather than the average atomic number,
has a more significant impact in lowering damping in Fe alloyed with light
elements. Moreover, FeV is confirmed to exhibit an intrinsic Gilbert damping
parameter of $\simeq$0.001, among the lowest ever reported for ferromagnetic
metals.",2004.04840v3
2020-12-22,Comparison of local and global gyrokinetic calculations of collisionless zonal flow damping in quasi-symmetric stellarators,"The linear collisionless damping of zonal flows is calculated for
quasi-symmetric stellarator equilibria in flux-tube, flux-surface, and
full-volume geometry. Equilibria are studied from the quasi-helical symmetry
configuration of the Helically Symmetric eXperiment (HSX), a broken symmetry
configuration of HSX, and the quasi-axial symmetry geometry of the National
Compact Stellarator eXperiment (NCSX). Zonal flow oscillations and long-time
damping affect the zonal flow evolution, and the zonal flow residual goes to
zero for small radial wavenumber. The oscillation frequency and damping rate
depend on the bounce-averaged radial particle drift in accordance with theory.
While each flux tube on a flux surface is unique, several different flux tubes
in HSX or NCSX can reproduce the zonal flow damping from a flux-surface
calculation given an adequate parallel extent. The flux-surface or flux-tube
calculations can accurately reproduce the full-volume long-time residual for
moderate $k_x$, but the oscillation and damping time scales are longer in local
representations, particularly for small $k_x$ approaching the system size.",2012.12213v2
2020-12-31,Damping of slow surface kink modes in solar photospheric waveguides modeled by one-dimensional inhomogeneities,"Given the recent interest in magnetohydrodynamic (MHD) waves in pores and
sunspot umbrae, we examine the damping of slow surface kink modes (SSKMs) by
modeling solar photospheric waveguides with a cylindrical inhomogeneity
comprising a uniform interior, a uniform exterior, and a continuous transition
layer (TL) in between. Performing an eigen-mode analysis in linear, resistive,
gravity-free MHD, our approach is idealized in that, among other things, our
equilibrium is structured only in the radial direction. We can nonetheless
address two damping mechanisms simultaneously, one being the Ohmic resistivity,
and the other being the resonant absorption of SSKMs in the cusp and
Alfv$\acute{\rm e}$n continua. We find that the relative importance of the two
mechanisms depends sensitively on the magnetic Reynolds number ($R_{\rm m}$).
Resonant absorption is the sole damping mechanism for realistically large
values of $R_{\rm m}$, and the cusp resonance in general dominates the
Alfv$\acute{\rm e}$n one unless the axial wavenumbers are at the lower end of
the observationally relevant range. We also find that the thin-boundary
approximation holds only when the TL-width-to-radius ratios are much smaller
than nominally expected. The Ohmic resistivity is far more important for
realistically small $R_{\rm m}$. Even in this case, SSKMs are only marginally
damped, with damping-time-to-period-ratios reaching $\sim 10$ in the parameter
range we examine.",2012.15426v1
2018-03-30,Damping of gravitational waves in a viscous Universe and its implication for dark matter self-interactions,"It is well known that a gravitational wave (GW) experiences the damping
effect when it propagates in a fluid with nonzero shear viscosity. In this
paper, we propose a new method to constrain the GW damping rate and thus the
fluid shear viscosity. By defining the effective distance which incorporates
damping effects, we can transform the GW strain expression in a viscous
Universe into the same form as that in a perfect fluid. Therefore, the
constraints of the luminosity distances from the observed GW events by LIGO and
Virgo can be directly applied to the effective distances in our formalism. We
exploit the lognormal likelihoods for the available GW effective distances and
a Gaussian likelihood for the luminosity distance inferred from the
electromagnetic radiation observation of the binary neutron star merger event
GW170817. Our fittings show no obvious damping effects in the current GW data,
and the upper limit on the damping rate with the combined data is $6.75 \times
10^{-4}\,{\rm Mpc}^{-1}$ at 95\% confidence level. By assuming that the dark
matter self-scatterings are efficient enough for the hydrodynamic description
to be valid, we find that a GW event from its source at a luminosity distance
$D\gtrsim 10^4\;\rm Mpc$ can be used to put a constraint on the dark matter
self-interactions.",1803.11397v1
2018-08-22,"Constructing a boosted, spinning black hole in the damped harmonic gauge","The damped harmonic gauge is important for numerical relativity computations
based on the generalized harmonic formulation of Einstein's equations, and is
used to reduce coordinate distortions near binary black hole mergers. However,
currently there is no prescription to construct quasiequilibrium binary black
hole initial data in this gauge. Instead, initial data are typically
constructed using a superposition of two boosted analytic single black hole
solutions as free data in the solution of the constraint equations. Then, a
smooth time-dependent gauge transformation is done early in the evolution to
move into the damped harmonic gauge. Using this strategy to produce initial
data in damped harmonic gauge would require the solution of a single black hole
in this gauge, which is not known analytically. In this work we construct a
single boosted, spinning, equilibrium BH in damped harmonic coordinates as a
regular time-independent coordinate transformation from Kerr-Schild
coordinates. To do this, we derive and solve a set of 4 coupled, nonlinear,
elliptic equations for this transformation, with appropriate boundary
conditions. This solution can now be used in the construction of damped
harmonic initial data for binary black holes.",1808.07490v3
2018-12-13,Neutrino damping in a fermion and scalar background,"We consider the propagation of a neutrino in a background composed of a
scalar particle and a fermion using a simple model for the coupling of the form
$\lambda\bar f_R\nu_L\phi$. In the presence of these interactions there can be
damping terms in the neutrino effective potential and index of refraction. We
calculate the imaginary part of the neutrino self-energy in this case, from
which the damping terms are determined. The results are useful in the context
of Dark Matter-neutrino interaction models in which the scalar and/or fermion
constitute the dark-matter. The corresponding formulas for models in which the
scalar particle couples to two neutrinos via a coupling of the form
$\lambda^{(\nu\nu\phi)}\bar\nu^c_R\nu_L\phi$ are then obtained as a special
case, which can be important also in the context of neutrino collective
oscillations in a supernova and in the Early Universe hot plasma before
neutrino decoupling. A particular feature of our results is that the damping
term in a $\nu\phi$ background is independent of the antineutrino-neutrino
asymmetry in the background. Therefore, the relative importance of the damping
term may be more significant if the neutrino-antineutrino asymmetry in the
background is small, because the leading $Z$-exchange and $\phi$-exchange
contributions to the effective potential, which are proportional to the
neutrino-antineutrino asymmetry, are suppressed in that case, while the damping
term is not.",1812.05672v2
2019-04-25,High Spin-Wave Propagation Length Consistent with Low Damping in a Metallic Ferromagnet,"We report ultra-low intrinsic magnetic damping in
Co$_{\text{25}}$Fe$_{\text{75}}$ heterostructures, reaching the low $10^{-4}$
regime at room temperature. By using a broadband ferromagnetic resonance
technique, we extracted the dynamic magnetic properties of several
Co$_{\text{25}}$Fe$_{\text{75}}$-based heterostructures with varying
ferromagnetic layer thickness. By estimating the eddy current contribution to
damping, measuring radiative damping and spin pumping effects, we found the
intrinsic damping of a 26\,nm thick sample to be $$\alpha_{\mathrm{0}} \lesssim
3.18\times10^{-4}$. Furthermore, using Brillouin light scattering microscopy we
measured spin-wave propagation lengths of up to $(21\pm1)\,\mathrm{\mu m}$ in a
26 nm thick Co$_{\text{25}}$Fe$_{\text{75}}$ heterostructure at room
temperature, which is in excellent agreement with the measured damping.",1904.11321v3
2019-11-02,Soft contribution to the damping rate of a hard photon in a weakly magnetized hot medium,"We consider weakly magnetized hot QED plasma comprising electrons and
positrons. There are three distinct dispersive (longitudinal and two
transverse) modes of a photon in a thermo-magnetic medium. At lowest order in
coupling constant, photon is damped in this medium via Compton scattering and
pair creation process. We evaluate the damping rate of hard photon by
calculating the imaginary part of the each transverse dispersive modes in a
thermo-magnetic QED medium. We note that one of the fermions in the loop of
one-loop photon self-energy is considered as soft and the other one is hard.
Considering the resummed fermion propagator in a weakly magnetized medium for
the soft fermion and the Schwinger propagator for hard fermion, we calculate
the soft contribution to the damping rate of hard photon. In weak field
approximation the thermal and thermo-magnetic contributions to damping rate get
separated out for each transverse dispersive mode. The total damping rate for
each dispersive mode in presence of magnetic field is found to be reduced than
that of the thermal one. This formalism can easily be extended to QCD plasma.",1911.00744v2
2020-09-25,Temperature dependence of the damping parameter in the ferrimagnet Gd$_3$Fe$_5$O$_{12}$,"The damping parameter ${\alpha}_{\text{FM}}$ in ferrimagnets defined
according to the conventional practice for ferromagnets is known to be strongly
temperature dependent and diverge at the angular momentum compensation
temperature, where the net angular momentum vanishes. However, recent
theoretical and experimental developments on ferrimagnetic metals suggest that
the damping parameter can be defined in such a way, which we denote by
${\alpha}_{\text{FiM}}$, that it is free of the diverging anomaly at the
angular momentum compensation point and is little dependent on temperature. To
further understand the temperature dependence of the damping parameter in
ferrimagnets, we analyze several data sets from literature for a ferrimagnetic
insulator, gadolinium iron garnet, by using the two different definitions of
the damping parameter. Using two methods to estimate the individual sublattice
magnetizations, which yield results consistent with each other, we found that
in all the used data sets, the damping parameter ${\alpha}_{\text{FiM}}$ does
not increase at the angular compensation temperature and shows no anomaly
whereas the conventionally defined ${\alpha}_{\text{FM}}$ is strongly dependent
on the temperature.",2009.12073v2
2020-09-25,A Complex Stiffness Human Impedance Model with Customizable Exoskeleton Control,"The natural impedance, or dynamic relationship between force and motion, of a
human operator can determine the stability of exoskeletons that use
interaction-torque feedback to amplify human strength. While human impedance is
typically modelled as a linear system, our experiments on a single-joint
exoskeleton testbed involving 10 human subjects show evidence of nonlinear
behavior: a low-frequency asymptotic phase for the dynamic stiffness of the
human that is different than the expected zero, and an unexpectedly consistent
damping ratio as the stiffness and inertia vary. To explain these observations,
this paper considers a new frequency-domain model of the human joint dynamics
featuring complex value stiffness comprising a real stiffness term and a
hysteretic damping term. Using a statistical F-test we show that the hysteretic
damping term is not only significant but is even more significant than the
linear damping term. Further analysis reveals a linear trend linking hysteretic
damping and the real part of the stiffness, which allows us to simplify the
complex stiffness model down to a 1-parameter system. Then, we introduce and
demonstrate a customizable fractional-order controller that exploits this
hysteretic damping behavior to improve strength amplification bandwidth while
maintaining stability, and explore a tuning approach which ensures that this
stability property is robust to muscle co-contraction for each individual.",2009.12446v1
2020-11-26,On the stabilization of breather-type solutions of the damped higher order nonlinear Schrödinger equation,"Spatially periodic breather solutions (SPBs) of the nonlinear Schr\""o\-dinger
(NLS) equation are frequently used to model rogue waves and are typically
unstable. In this paper we study the effects of dissipation and higher order
nonlinearities on the stabilization of both single and multi-mode SPBs in the
framework of a damped higher order NLS (HONLS) equation. We observe the onset
of novel instabilities associated with the development of critical states which
result from symmetry breaking in the damped HONLS system. We broaden the
Floquet characterization of instabilities of solutions of the NLS equation,
using an even 3-phase solution of the NLS as an example, to show instabilities
are associated with degenerate complex elements of both the periodic and
continuous Floquet spectrum. As a result the Floquet criteria for the
stabilization of a solution of the damped HONLS centers around the elimination
of all complex degenerate elements of the spectrum. For an initial SPB with a
given mode structure, a perturbation analysis shows that for short time only
the complex double points associated with resonant modes split under the damped
HONLS while those associated with nonresonant modes remain effectively closed.
The corresponding damped HONLS numerical experiments corroborate that
instabilities associated with nonresonant modes persist on a longer time scale
than the instabilities associated with resonant modes.",2011.13334v1
2021-02-24,Finding the mechanism of wave energy flux damping in solar pores using numerical simulations,"Context. Solar magnetic pores are, due to their concentrated magnetic fields,
suitable guides for magnetoacoustic waves. Recent observations have shown that
propagating energy flux in pores is subject to strong damping with height;
however, the reason is still unclear. Aims. We investigate possible damping
mechanisms numerically to explain the observations. Methods. We performed 2D
numerical magnetohydrodynamic (MHD) simulations, starting from an equilibrium
model of a single pore inspired by the observed properties. Energy was inserted
into the bottom of the domain via different vertical drivers with a period of
30s. Simulations were performed with both ideal MHD and non-ideal effects.
Results. While the analysis of the energy flux for ideal and non-ideal MHD
simulations with a plane driver cannot reproduce the observed damping, the
numerically predicted damping for a localized driver closely corresponds with
the observations. The strong damping in simulations with localized driver was
caused by two geometric effects, geometric spreading due to diverging field
lines and lateral wave leakage.",2102.12420v1
2021-09-08,Room-Temperature Intrinsic and Extrinsic Damping in Polycrystalline Fe Thin Films,"We examine room-temperature magnetic relaxation in polycrystalline Fe films.
Out-of-plane ferromagnetic resonance (FMR) measurements reveal Gilbert damping
parameters of $\approx$ 0.0024 for Fe films with thicknesses of 4-25 nm,
regardless of their microstructural properties. The remarkable invariance with
film microstructure strongly suggests that intrinsic Gilbert damping in
polycrystalline metals at room temperature is a local property of nanoscale
crystal grains, with limited impact from grain boundaries and film roughness.
By contrast, the in-plane FMR linewidths of the Fe films exhibit distinct
nonlinear frequency dependences, indicating the presence of strong extrinsic
damping. To fit our in-plane FMR data, we have used a grain-to-grain two-magnon
scattering model with two types of correlation functions aimed at describing
the spatial distribution of inhomogeneities in the film. However, neither of
the two correlation functions is able to reproduce the experimental data
quantitatively with physically reasonable parameters. Our findings advance the
fundamental understanding of intrinsic Gilbert damping in structurally
disordered films, while demonstrating the need for a deeper examination of how
microstructural disorder governs extrinsic damping.",2109.03684v2
2022-04-08,Damped Strichartz estimates and the incompressible Euler--Maxwell system,"Euler--Maxwell systems describe the dynamics of inviscid plasmas. In this
work, we consider an incompressible two-dimensional version of such systems and
prove the existence and uniqueness of global weak solutions, uniformly with
respect to the speed of light $c\in (c_0,\infty)$, for some threshold value
$c_0>0$ depending only on the initial data. In particular, the condition
$c>c_0$ ensures that the velocity of the plasma nowhere exceeds the speed of
light and allows us to analyze the singular regime $c\to\infty$.
  The functional setting for the fluid velocity lies in the framework of
Yudovich's solutions of the two-dimensional Euler equations, whereas the
analysis of the electromagnetic field hinges upon the refined interactions
between the damping and dispersive phenomena in Maxwell's equations in the
whole space. This analysis is enabled by the new development of a robust
abstract method allowing us to incorporate the damping effect into a variety of
existing estimates. The use of this method is illustrated by the derivation of
damped Strichartz estimates (including endpoint cases) for several dispersive
systems (including the wave and Schr\""odinger equations), as well as damped
maximal regularity estimates for the heat equation. The ensuing damped
Strichartz estimates supersede previously existing results on the same systems.",2204.04277v3
2022-05-11,A new look at the frequency-dependent damping of slow-mode waves in the solar corona,"Being directly observed in the Doppler shift and imaging data and indirectly
as quasi-periodic pulsations in solar and stellar flares, slow magnetoacoustic
waves offer an important seismological tool for probing many vital parameters
of the coronal plasma. A recently understood active nature of the solar corona
for magnetoacoustic waves, manifested through the phenomenon of wave-induced
thermal misbalance, led to the identification of new natural mechanisms for the
interpretation of observed properties of waves. A frequency-dependent damping
of slow waves in various coronal plasma structures remains an open question, as
traditional wave damping theories fail to match observations. We demonstrate
that accounting for the back-reaction caused by thermal misbalance on the wave
dynamics leads to a modification of the relationship between the damping time
and oscillation period of standing slow waves, prescribed by the linear theory.
The modified relationship is not of a power-law form and has the equilibrium
plasma conditions and properties of the coronal heating/cooling processes as
free parameters. It is shown to readily explain the observed scaling of the
damping time with period of standing slow waves in hot coronal loops.
Functional forms of the unknown coronal heating process, consistent with the
observed frequency-dependent damping, are seismologically revealed.",2205.05346v1
2022-12-13,The Effect of Internal Damping on Locomotion in Frictional Environments,"The gaits of undulating animals arise from a complex interaction of their
central nervous system, muscle, connective tissue, bone, and environment. As a
simplifying assumption, many previous studies have often assumed that
sufficient internal force is available to produce observed kinematics, thus not
focusing on quantifying the interconnection between muscle effort, body shape,
and external reaction forces. This interplay, however, is critical to
locomotion performance in crawling animals, especially when accompanied by body
viscoelasticity. Moreover, in bio-inspired robotic applications, the body's
internal damping is indeed a parameter that the designer can tune. Still, the
effect of internal damping is not well understood. This study explores how
internal damping affects the locomotion performance of a crawler with a
continuous, visco-elastic, nonlinear beam model. Crawler muscle actuation is
modeled as a traveling wave of bending moment propagating posteriorly along the
body. Consistent with the friction properties of the scales of snakes and
limbless lizards, environmental forces are modeled using anisotropic Coulomb
friction. It is found that by varying the crawler body's internal damping, the
crawler's performance can be altered, and distinct gaits could be achieved,
including changing the net locomotion direction from forward to back. We will
discuss this forward and backward control and identify the optimal internal
damping for peak crawling speed.",2212.06290v1
2023-01-19,Inverse Problems of Identifying the Unknown Transverse Shear Force in the Euler-Bernoulli Beam with Kelvin-Voigt Damping,"In this paper, we study the inverse problems of determining the unknown
transverse shear force $g(t)$ in a system governed by the damped
Euler-Bernoulli equation $\rho(x)u_{tt}+\mu(x)u_t+ (r(x)u_{xx})_{xx}+
(\kappa(x)u_{xxt})_{xx}=0, ~(x,t)\in (0,\ell)\times(0,T],$ subject to the
boundary conditions $u(0,t) =0$, $u_{x}(0,t)=0$,
$\left[r(x)u_{xx}+\kappa(x)u_{xxt}\right]_{x=\ell} =0$,
$-\left[\big(r(x)u_{xx}+\kappa(x)u_{xxt}\big)_{x}\right]_{x=\ell}=g(t)$, $t\in
[0,T]$, from the measured deflection $\nu(t):=u(\ell,t)$, $t \in [0,T]$, and
from the bending moment $\omega(t):=-\left(
r(0)u_{xx}(0,t)+\kappa(0)u_{xxt}(0,t) \right)$, $t \in [0,T]$, where the terms
$(\kappa(x)u_{xxt})_{xx}$ and $\mu(x)u_t$ account for the Kelvin-Voigt damping
and external damping, respectively.
  The main purpose of this study is to analyze the Kelvin-Voigt damping effect
on determining the unknown transverse shear force (boundary input) through the
given boundary measurements. The inverse problems are transformed into
minimization problems for Tikhonov functionals, and it is shown that the
regularized functionals admit unique solutions for the inverse problems. By
suitable regularity on the admissible class of shear force $g(t),$ we prove
that these functionals are Fr\'echet differentiable, and the derivatives are
expressed through the solutions of corresponding adjoint problems posed with
measured data as boundary data associated with the direct problem. The
solvability of these adjoint problems is obtained under the minimal regularity
of the boundary data $g(t)$, which turns out to be the regularizing effect of
the Kelvin-Voigt damping in the direct problem.",2301.07931v1
2023-03-28,Escape Kinetics of an Underdamped Colloidal Particle from a Cavity through Narrow Pores,"It is often desirable to know the controlling mechanism of survival
probability of nano - or microscale particles in small cavities such as, e.g.,
confined submicron particles in fiber beds of high-efficiency filter media or
ions/small molecules in confined cellular structures. Here we address this
issue based on numerical study of the escape kinetics of inertial Brownian
colloidal particles from various types of cavities with single and multiple
pores. We consider both the situations of strong and weak viscous damping. Our
simulation results show that as long as the thermal length is larger than the
cavity size the mean exit time remains insensitive to the medium viscous
damping. On further increasing damping strength, a linear relation between
escape rate and damping strength emerges gradually. This result is in sharp
contrast to the energy barrier crossing dynamics where the escape rate exhibits
a turnover behavior as a function of the damping strength. Moreover, in the
ballistic regime, the exit rate is directly proportional to the pore width and
the thermal velocity. All these attributes are insensitive to the cavity as
well as the pore structures. Further, we show that the effects of pore
structure variation on the escape kinetics are conspicuously different in the
low damping regimes compared to the overdamped situation. Apart from direct
applications in biology and nanotechnology, our simulation results can
potentially be used to understand diffusion of living or artificial micro/nano
objects, such as bacteria, virus, Janus Particle etc. where memory effects play
dictating roles.",2303.16092v1
2023-06-05,Damping of coronal oscillations in self-consistent 3D radiative MHD simulations of the solar atmosphere,"Oscillations are abundant in the solar corona. Coronal loop oscillations are
typically studied using highly idealised models of magnetic flux tubes. In
order to improve our understanding of coronal oscillations, it is necessary to
consider the effect of realistic magnetic field topology and density
structuring. We analyse the damping of coronal oscillations using a
self-consistent 3D radiation-MHD simulation of the solar atmosphere spanning
from the convection zone into the corona, the associated oscillation
dissipation and heating, and finally the physical processes responsible for the
damping and dissipation. The simulated corona formed in such a model does not
depend on any prior assumptions about the shape of the coronal loops. We find
that the bundle of magnetic loops shows damped transverse oscillations in
response to perturbations in two separate instances with oscillation periods of
177 s and 191 s, velocity amplitudes of 10 km/s and 16 km/s and damping times
of 176 s and 198 s, respectively. The coronal oscillations lead to the
development of velocity shear in the simulated corona resulting in the
formation of vortices seen in the velocity field caused by the Kelvin-Helmholtz
instability, contributing to the damping and dissipation of the transverse
oscillations. The oscillation parameters and evolution observed are in line
with the values typically seen in observations of coronal loop oscillations.
The dynamic evolution of the coronal loop bundle suggests the models of
monolithic and static coronal loops with constant lengths might need to be
re-evaluated by relaxing the assumption of highly idealised waveguides.",2306.02770v1
2023-08-22,Investigating the characteristic shape and scatter of intergalactic damping wings during reionization,"Ly$\alpha$ damping wings in the spectra of bright objects at high redshift
are a useful probe of the ionization state of the intergalactic medium during
the reionization epoch. It has recently been noted that, despite the
inhomogeneous nature of reionization, these damping wings have a characteristic
shape which is a strong function of the volume-weighted average neutral
hydrogen fraction of the intergalactic medium. We present here a closer
examination of this finding using a simulation of patchy reionization from the
Sherwood-Relics simulation suite. We show that the characteristic shape and
scatter of the damping wings are determined by the average neutral hydrogen
density along the line of sight, weighted by its contribution to the optical
depth producing the damping wing. We find that there is a redshift dependence
in the characteristic shape due to the expansion of the Universe. Finally, we
show that it is possible to differentiate between the shapes of damping wings
in galaxies and young (or faint) quasars at different points in the
reionization history at large velocity offsets from the point where the
transmission first reaches zero.",2308.11709v1
2023-10-02,Characterizing the Velocity-Space Signature of Electron Landau Damping,"Plasma turbulence plays a critical role in the transport of energy from
large-scale magnetic fields and plasma flows to small scales, where the
dissipated turbulent energy ultimately leads to heating of the plasma species.
A major goal of the broader heliophysics community is to identify the physical
mechanisms responsible for the dissipation of the turbulence and to quantify
the consequent rate of plasma heating. One of the mechanisms proposed to damp
turbulent fluctuations in weakly collisional space and astrophysical plasmas is
electron Landau damping. The velocity-space signature of electron energization
by Landau damping can be identified using the recently developed field-particle
correlation technique. Here, we perform a suite of gyrokinetic turbulence
simulations with ion plasma beta values of 0.01, 0.1, 1, and 10 and use the
field-particle correlation technique to characterize the features of the
velocity-space signatures of electron Landau damping in turbulent plasma
conditions consistent with those observed in the solar wind and planetary
magnetospheres. We identify the key features of the velocity-space signatures
of electron Landau damping as a function of varying plasma \beta_i to provide a
critical framework for interpreting the results of field-particle correlation
analysis of in situ spacecraft observations of plasma turbulence.",2310.01242v2
2023-10-07,OEDG: Oscillation-eliminating discontinuous Galerkin method for hyperbolic conservation laws,"Controlling spurious oscillations is crucial for designing reliable numerical
schemes for hyperbolic conservation laws. This paper proposes a novel, robust,
and efficient oscillation-eliminating discontinuous Galerkin (OEDG) method on
general meshes, motivated by the damping technique in [Lu, Liu, and Shu, SIAM
J. Numer. Anal., 59:1299-1324, 2021]. The OEDG method incorporates an OE
procedure after each Runge-Kutta stage, devised by alternately evolving
conventional semidiscrete DG scheme and a damping equation. A novel damping
operator is carefully designed to possess scale-invariant and
evolution-invariant properties. We rigorously prove optimal error estimates of
the fully discrete OEDG method for linear scalar conservation laws. This might
be the first generic fully-discrete error estimates for nonlinear DG schemes
with automatic oscillation control mechanism. The OEDG method exhibits many
notable advantages. It effectively eliminates spurious oscillations for
challenging problems across various scales and wave speeds, without
problem-specific parameters. It obviates the need for characteristic
decomposition in hyperbolic systems. It retains key properties of conventional
DG method, such as conservation, optimal convergence rates, and
superconvergence. Moreover, it remains stable under normal CFL condition. The
OE procedure is non-intrusive, facilitating integration into existing DG codes
as an independent module. Its implementation is easy and efficient, involving
only simple multiplications of modal coefficients by scalars. The OEDG approach
provides new insights into the damping mechanism for oscillation control. It
reveals the role of damping operator as a modal filter and establishes close
relations between the damping and spectral viscosity techniques. Extensive
numerical results confirm the theoretical analysis and validate the
effectiveness and advantages of the OEDG method.",2310.04807v1
2023-12-07,Probing levitodynamics with multi-stochastic forces and the simple applications on the dark matter detection in optical levitation experiment,"If the terrestrial environment is permeated by dark matter, the levitation
experiences damping forces and fluctuations attributed to dark matter. This
paper investigates levitodynamics with multiple stochastic forces, including
thermal drag, photon recoil, feedback, etc., assuming that all of these forces
adhere to the fluctuation-dissipation theorem. The ratio of total damping to
the stochastic damping coefficient distinguishes the levitodynamics from cases
involving only one single stochastic force. The heating and cooling processes
are formulated to determine the limits of temperature change. All sources of
stochastic forces are comprehensively examined, revealing that dark matter
collisions cannot be treated analogously to fluid dynamics. Additionally, a
meticulous analysis is presented, elucidating the intricate relationship
between the fundamental transfer cross-section and the macroscopic transfer
cross-section. While the dark damping coefficient is suppressed by the mass of
the levitated particle, scattering can be coherently enhanced based on the
scale of the component microscopic particle, the atomic form factor, and the
static structure factor. Hence, dark damping holds the potential to provide
valuable insights into the detection of the macroscopic strength of fundamental
particles. We propose experimental procedures for levitation and employ linear
estimation to extract the dark damping coefficient. Utilizing current
levitation results, we demonstrate that the fundamental transfer cross section
of dark matter can be of the order $\sigma^{\rm D}_{T}\lsim {\cal
O}(10^{-26})\rm cm^2$.",2312.04202v2
2024-01-23,Damped kink motions in a system of two solar coronal tubes with elliptic cross-sections,"This study is motivated by observations of coordinated transverse
displacements in neighboring solar active region loops, addressing specifically
how the behavior of kink motions in straight two-tube equilibria is impacted by
tube interactions and tube cross-sectional shapes.We work with linear, ideal,
pressureless magnetohydrodynamics. Axially standing kink motions are examined
as an initial value problem for transversely structured equilibria involving
two identical, field-aligned, density-enhanced tubes with elliptic
cross-sections (elliptic tubes). Continuously nonuniform layers are implemented
around both tube boundaries. We numerically follow the system response to
external velocity drivers, largely focusing on the quasi-mode stage of internal
flows to derive the pertinent periods and damping times. The periods and
damping times we derive for two-circular-tube setups justify available modal
results found with the T-matrix approach. Regardless of cross-sectional shapes,
our nonuniform layers feature the development of small-scale shears and energy
accumulation around Alf\'ven resonances, indicative of resonant absorption and
phase-mixing. As with two-circular-tube systems, our configurational symmetries
make it still possible to classify lower-order kink motions by the polarization
and symmetric properties of the internal flows; hence such mode labels as $S_x$
and $A_x$. However, the periods and damping times for two-elliptic-tube setups
further depend on cross-sectional aspect ratios, with $A_x$ motions
occasionally damped less rapidly than $S_x$ motions. We find uncertainties up
to $\sim 20\%$ ($\sim 50\%$) for the axial Alfven time (the inhomogeneity
lengthscale) if the periods (damping times) computed for two-elliptic-tube
setups are seismologically inverted with canonical theories for isolated
circular tubes.",2401.12885v2
1995-02-08,The Chemical Evolution of Damped Lyman Alpha Galaxies,"Measurements of element abundances in damped Lyman alpha systems are
providing new means to investigate the chemical evolution of galaxies,
particularly at early times. We review progress in this area, concentrating on
recent efforts to extend the range of existing surveys to both higher and lower
redshifts.",9502047v1
1996-01-19,The Chemical Enrichment History of Damped Lyman-alpha Galaxies,"Studies of damped Lyman-alpha absorption systems in quasar spectra are
yielding very interesting results regarding the chemical evolution of these
galaxies. We present some preliminary results from such a program.",9601098v1
1997-01-30,Initial Chemical Enrichment in Galaxies,"We present evidence that damped Lyman-alpha galaxies detected in spectra of
quasars may not have started forming stars until the redshift z~3. If damped
Lyman-alpha absorbers are the progenitors of disk galaxies, then the above
result may indicate that star formation in galactic disks first began at z~3.",9701241v1
1997-10-24,The N/Si Abundance Ratio in Fifteen Damped Lyman-alpha Galaxies: Implications for the Origin of Nitrogen,"Galactic chemical evolution model calculations indicate that there should be
considerable scatter in the observed N/O ratios at a fixed metallicity (O/H)
for galaxies with very low metallicities due to the delayed release of primary
N from intermediate mass stars relative to that of O from short-lived massive
stars. Moreover, the scatter should increase progressively toward decreasing
metallicity. Such effects have not been convincingly demonstrated by
observations of H II regions in nearby metal-poor galaxies, raising doubts
about the time-delay model of primary N production. Pettini et al and Lipman et
al realized the utility of high-redshift damped Lyman-alpha galaxies for
gaining further insights into the origin of N and discussed abundances in three
damped Lyman-alpha galaxies. Since abundance measurements for O are generally
unavailable for damped Lyman-alpha galaxies, they used N/Si or N/S in place of
N/O under the reasonable assumption that the abundance ratios O/Si and O/S are
the same as solar in damped Lyman-alpha galaxies. We discuss observations of
heavy element abundances in 15 high-redshift (z>2) damped Lyman-alpha galaxies,
many of which have metallicities comparable to or lower than the lowest
metallicity galaxy known locally (I Zw 18). We find that the N/Si ratios in
damped Lyman-alpha galaxies exhibit a very large scatter (about 1 dex) at
[Si/H]~-2 and there is some indication that the scatter increases toward
decreasing metallicity. Considerations of various sources of uncertainties
suggest that they are not likely the main causes of the large scatter. These
results thus provide strong support for the time-delay model of primary N
production in intermediate mass stars if, indeed, O/Si=solar in damped
Lyman-alpha galaxies.",9710266v2
2001-06-05,On Nonlinear Alfvén Waves Generated by Cosmic Ray Streaming Instability,"Nonlinear damping of parallel propagating Alfv\'en waves in high-$\beta$
plasma is considered. Trapping of thermal ions and Coulomb collisions are taken
into account. Saturated damping rate is calculated. Applications are made for
cosmic ray propagation in the Galaxy.",0106078v1
2001-10-15,The UCSD HIRES/KeckI Damped Lya Abundance Database: II. The Implications,"We present a comprehensive analysis of the damped Lya abundance database
presented in the first paper of this series. This database provides a
homogeneous set of abundance measurements for many elements including Si, Cr,
Ni, Zn, Fe, Al, S, Co, O, and Ar from 38 damped Lya systems with z > 1.5. With
little exception, these damped Llya systems exhibit very similar relative
abundances. There is no significant correlation in X/Fe with [Fe/H] metallicity
and the dispersion in X/Fe is small at all metallicity.
  We search the database for trends indicative of dust depletion and in a few
cases find strong evidence. Specifically, we identify a correlation between
[Si/Ti] and [Zn/Fe] which is unambiguous evidence for depletion.
  We present a discussion on the nucleosynthetic history of the damped Lya
systems by focusing on abundance patterns which are minimally affected by dust
depletion. We find [Si/Fe] -> +0.25 dex as [Zn/Fe] -> 0 and that the [Si/Fe]
values exhibit a plateau of ~+0.3 dex at [Si/H] < -1.5 dex. Together these
trends indicate significant alpha-enrichment in the damped Lya systems at low
metallicity, an interpretation further supported by the observed O/Fe, S/Fe and
Ar/Fe ratios. We also discuss Fe-peak nucleosynthesis and the odd-even effect.
  To assess the impact of dust obscuration, we present estimates of the
dust-to-gas ratios for the damped Lya sightlines and crudely calculate dust
extinction corrections. The distribution of extinction corrections suggests the
effects of dust obscuration are minimal and that the population of 'missing'
damped systems has physical characteristics similar to the observed sample.
  We update our investigation on the chemical evolution of the early universe
in neutral gas. [significantly abridged]",0110351v1
2005-09-05,"Comment on ""Damping of Tensor Modes in Cosmology""","We provide an analytic solution to the short wave length limit of the
integro-differential equation describing the damping of the tensor modes of
gravitational waves.",0509096v2
1997-02-12,Crossover from coherent to incoherent dynamics in damped quantum systems,"The destruction of quantum coherence by environmental influences is
investigated taking the damped harmonic oscillator and the dissipative
two-state system as prototypical examples. It is shown that the location of the
coherent-incoherent transition depends to a large degree on the dynamical
quantity under consideration.",9702115v1
1998-06-05,Dielectric formalism and damping of collective modes in trapped Bose-Einstein condensed gases,"We present the general dielectric formalism for Bose-Einstein condensed
systems in external potential at finite temperatures. On the basis of a model
arising within this framework as a first approximation in an intermediate
temperature region for large condensate we calculate the damping of low-energy
excitations in the collisionless regime.",9806079v1
1999-05-27,Do correlations create an energy gap in electronic bilayers? Critical analysis of different approaches,"This paper investigates the effect of correlations in electronic bilayers on
the longitudinal collective mode structure. We employ the dielectric
permeability constructed by means of the classical theory of moments. It is
shown that the neglection of damping processes overestimates the role of
correlations. We conclude that the correct account of damping processes leads
to an absence of an energy gap.",9905405v1
1999-11-16,Damping of low-energy excitations of a Bose-condensed gas in the hydrodynamic regime,"We develop a theory to describe the damping of elementary excitations of a
Bose-condensed gas in the hydrodynamic regime for the thermal cloud. We discuss
second sound in a spatially homogeneous gas and the lowest excitations of a
trapped condensate.",9911238v2
2002-04-18,"Faraday patterns in Bose-Einstein condensates. Amplitude equation for rolls in the parametrically driven, damped Gross-Pitaevskii equation","The parametrically driven, damped Gross-Pitaevskii equation, which models
Bose-Einstein condensates in which the interatomic s-wave scattering length is
modulated in time, is shown to support spatially modulated states in the form
of rolls. A Landau equation with broken phase symmetry is derived, which
governs the dynamics of the roll amplitude.",0204406v1
2002-11-14,Sound damping in ferrofluids: Magnetically enhanced compressional viscosity,"The damping of sound waves in magnetized ferrofluids is investigated and
shown to be considerably higher than in the non-magnetized case. This fact may
be interpreted as a field-enhanced, effective compressional viscosity -- in
analogy to the ubiquitous field-enhanced shear viscosity that is known to be
the reason for many unusual behavior of ferrofluids under shear.",0211297v1
2003-10-23,Input and output in damped quantum systems III: Formulation of damped systems driven by Fermion fields,"A comprehensive input-output theory is developed for Fermionic input fields.
Quantum stochastic differential equations are developed in both the Ito and
Stratonovich forms. The major technical issue is the development of a formalism
which takes account of anticommutation relations between the Fermionic driving
field and those system operators which can change the number of Fermions within
the system.",0310542v1
2004-01-12,Nonexponential motional damping of impurity atoms in Bose-Einstein condensates,"We demonstrate that the damping of the motion of an impurity atom injected at
a supercritical velocity into a Bose-Einstein condensate can exhibit
appreciable deviation from the exponential law on time scales of $10^{-5}$ s.",0401172v1
2005-02-21,Two Transitions in the Damping of a Unitary Fermi Gas,"We measure the temperature dependence of the radial breathing mode in an
optically trapped, strongly-interacting Fermi gas of $^6$Li, just above the
center of a broad Feshbach resonance. The frequency remains close to the
unitary hydrodynamic value, while the damping rate reveals transitions at two
well-separated temperatures, consistent with the existence of atom pairs above
a superfluid transition.",0502507v1
2005-05-10,Fluctuation-dissipation considerations and damping models for ferromagnetic materials,"The role of fluctuation-dissipation relations (theorems) for the
magnetization dynamics with Landau-Lifshitz-Gilbert and Bloch-Bloembergen
damping terms are discussed. We demonstrate that the use of the Callen-Welton
fluctuation-dissipation theorem that was proven for Hamiltonian systems can
give an inconsistent result for magnetic systems with dissipation.",0505259v1
1994-07-04,Cat States and Single Runs for the Damped Harmonic Oscillator,"We discuss the fate of initial states of the cat type for the damped harmonic
oscillator, mostly employing a linear version of the stochastic Schr\""odinger
equation. We also comment on how such cat states might be prepared and on the
relation of single realizations of the noise to single runs of experiments.",9407001v1
2000-10-27,Damping and the Hartree Ensemble Approximation,"We study a Hartree ensemble approximation for real-time dynamics in the toy
model of 1+1 dimensional scalar field theory. Damping behavior seen in
numerical simulations is compared with analytical predictions based on
perturbation theory in the original (non-Hartree-approximated) model.",0010054v1
1995-03-21,APPLICATIONS OF HIGH-TEMPERATURE FIELD THEORY TO HEAVY-ION COLLISIONS,"A recent development in finite temperature field theory, the so-called
Braaten-Pisarski method, and its application to properties of a quark-gluon
plasma, possibly formed in relativistic heavy ion collisions, are reviewed. In
particular parton damping rates, the energy loss of energetic partons,
thermalization times, viscosity, and production and damping rates of hard
photons are discussed.",9503400v1
1996-03-19,Damping Rate and Lyapunov Exponent of a Higgs Field at High Temperature,"The damping rate of a Higgs field at zero momentum is calculated using the
Braaten-Pisarski method and compared to the Lyapunov exponent of the classical
SU(2) Yang-Mills Higgs system.",9603339v1
1997-04-30,Comments on the Erhan-Schlein model of damping the pomeron flux at small x-pomeron,"We explore the theoretical and experimental consequences of a model proposed
by Samim Erhan and Peter Schlein for unitarizing the diffractive amplitude by
damping the pomeron flux at small x-pomeron and conclude that the model is
unphysical and contradicts well established experimental data.",9704454v1
1998-03-26,The Nonlinear Spatial Damping Rate in QGP,"The derivative expansion method has been used to solve the semiclassical
kinetic equations of quark-gluon plasma (QGP). The nonlinear spatial damping
rate, the imaginary part of the wave vector, for the longitudinal secondary
color waves in the long wavelength limit has been calculated numerically.",9803455v1
2006-07-27,Long-Time Asymptotic Behavior of Dissipative Boussinesq System,"In this paper, we study various dissipative mechanics associated with the
Boussinesq systems which model two-dimensional small amplitude long wavelength
water waves. We will show that the decay rate for the damped one-directional
model equations, such as the KdV and BBM equations, holds for some of the
damped Boussinesq systems which model two-directional waves.",0607708v1
2006-12-27,Stochastic inertial manifolds for damped wave equations,"In this paper, stochastic inertial manifold for damped wave equations
subjected to additive white noise is constructed by the Lyapunov-Perron method.
It is proved that when the intensity of noise tends to zero the stochastic
inertial manifold converges to its deterministic counterpart almost surely.",0612774v1
2007-01-19,On the Domain of Analyticity and Small Scales for the Solutions of the Damped-driven 2D Navier-Stokes Equations,"We obtain a logarithmically sharp estimate for the space-analyticity radius
of the solutions of the damped-driven 2D Navier-Stokes equations with periodic
boundary conditions and relate this to the small scales in this system. This
system is inspired by the Stommel--Charney barotropic ocean circulation model.",0701530v1
2002-09-04,Wigner function for damped systems,"Both classical and quantum damped systems give rise to complex spectra and
corresponding resonant states. We investigate how resonant states, which do not
belong to the Hilbert space, fit the phase space formulation of quantum
mechanics. It turns out that one may construct out of a pair of resonant states
an analog of the stationary Wigner function.",0209008v1
2004-12-14,Two-Ion Dusty Plasma Waves and Landau Damping,"The paper analyses the properties of dusty plasmas in the extreme conditions
when the free electrons are absent. The nonlinear Korteveg de Vries equation
with a nonlocal (integral) term in a small parameter approximation is derived.
The conditions are determined when the integral term is essential hence the
Landau damping of two-ion-dusty plasma waves is substantial.",0412033v1
2002-10-16,Dependence of Nuclear Level Density on Vibrational State Damping,"The response function approach is proposed to include vibrational state in
calculation of level density. The calculations show rather strong dependence of
level density on the relaxation times of collective state damping.",0210048v1
1999-02-09,One-Dimensional Motion of Sommerfeld Sphere in Potential Hole in Classical Electrodynamics: Inside the Hole,"Equation of motion of Sommerfeld sphere in the one-dimensional potential
hole, produced by two equal charges on some distance from each other, is
numerically investigated. Two types of solutions are found: (i) damping
oscillations, (ii) oscillations without damping (radiationless motion).
Solutions with growing amplitude (""climbing-up-the-wall solution"") for chosen
initial conditions were not founded.",9902018v3
2000-03-23,The Hawking-Unruh Temperature and Damping in a Linear Focusing Channel,"The Hawking-Unruh effective temperature, hbar a* / 2 pi c k, due to quantum
fluctuations in the radiation of an accelerated charged-particle beam can be
used to show that transverse oscillations of the beam in a practical linear
focusing channel damp to the quantum-mechanical limit. A comparison is made
between this behavior and that of beams in a wiggler.",0003061v1
2003-06-17,Ruchhardt Oscillator Decay- Thermodynamic basis for Hysteretic Damping,"Using thermodynamic arguments based on the ideal gas law, it is shown that
hysteretic (also called structural) damping is the natural form of energy
dissipation for this classic oscillator that is used to measure the ratio of
heat capacities for a gas.",0306136v1
2005-08-25,Rutherford scattering with radiation damping,"We study the effect of radiation damping on the classical scattering of
charged particles. Using a perturbation method based on the Runge-Lenz vector,
we calculate radiative corrections to the Rutherford cross section, and the
corresponding energy and angular momentum losses.",0508186v2
2006-01-18,Expressions for frictional and conservative force combinations within the dissipative Lagrange-Hamilton formalism,"Dissipative Lagrangians and Hamiltonians having Coulomb, viscous and
quadratic damping,together with gravitational and elastic terms are presented
for a formalism that preserves the Hamiltonian as a constant of the motion.
Their derivations are also shown. The resulting L's and H's may prove useful in
exploring new types of damped quantum systems.",0601133v1
1997-03-27,Macroscopic quantum damping in SQUID rings,"The measurement process is introduced in the dynamics of Josephson devices
exhibiting quantum behaviour in a macroscopic degree of freedom. The
measurement is shown to give rise to a dynamical damping mechanism whose
experimental observability could be relevant to understand decoherence in
macroscopic quantum systems.",9703052v1
2005-07-19,Radiation reaction and quantum damped harmonic oscillator,"By taking a Klein-Gordon field as the environment of an harmonic oscillator
and using a new method for dealing with quantum dissipative systems (minimal
coupling method), the quantum dynamics and radiation reaction for a quantum
damped harmonic oscillator investigated. Applying perturbation method, some
transition probabilities indicating the way energy flows between oscillator,
reservoir and quantum vacuum, obtained",0507179v1
2005-08-18,Density operator and entropy of the damped quantum harmonic oscillator,"The expression for the density operator of the damped harmonic oscillator is
derived from the master equation in the framework of the Lindblad theory for
open quantum systems. Then the von Neumann entropy and effective temperature of
the system are obtained. The entropy for a state characterized by a Wigner
distribution function which is Gaussian in form is found to depend only on the
variance of the distribution function.",0508141v1
2006-03-03,On the damping of the angular momentum of three harmonic oscillators,"In the frame of the Lindblad theory of open quantum systems, the system of
three uncoupled harmonic oscillators with opening operators linear in the
coordinates and momenta of the considered system is analyzed. The damping of
the angular momentum and of its projection is obtained.",0603029v1
2006-10-10,Simultaneous amplification and non-symmetric amplitude damping of two-mode Gaussian state,"The evolution of two-mode Gaussian state under symmetric amplification,
non-symmetric damping and thermal noise is studied. The time dependent solution
of the state characteristic function is obtained. The separability criterions
are given for the final state of weak amplification as well as strong
amplification.",0610070v1
2007-10-13,The separability of tripartite Gaussian state with amplification and amplitude damping,"Tripartite three mode Gaussian state undergoes parametric amplification and
amplitude damping as well as thermal noise is studied. In the case of a state
totally symmetrically interacting with the environment, the time dependent
correlation matrix of the state in evolution is given. The conditions for fully
separability and fully entanglement of the final tripartite three mode Gaussian
state are worked out.",0710.2570v1
2007-12-16,Nonadditive quantum error correcting codes adapted to the ampltitude damping channel,"A family of high rate quantum error correcting codes adapted to the amplitude
damping channel is presented. These codes are nonadditive and exploit
self-complementarity structure to correct all first-order errors. Their rates
can be higher than 1/2. The recovery operations of these codes can be generated
by a simple algorithm and have a projection nature, which makes them
potentially easy to implement.",0712.2586v1
2007-12-22,Chaos in an intermittently driven damped oscillator,"We observe chaotic dynamics in a damped linear oscillator, which is driven
only at certain regions of phase space. Both deterministic and random drives
are studied. The dynamics is characterized using standard techniques of
nonlinear dynamics. Interchanging roles of determinism and stochasticity is
also considered.",0712.3827v2
2008-03-01,Well-posedness of the IBVP for 2-D Euler Equations with Damping,"In this paper we focus on the initial-boundary value problem of the 2-D
isentropic Euler equations with damping. We prove the global-in-time existence
of classical solution to the initial-boundary value problem by the method of
energy estimates.",0803.0039v1
2008-03-27,Shear viscosity of degenerate electron matter,"We calculate the partial electron shear viscosity $\eta_{ee}$ limited by
electron-electron collisions in a strongly degenerate electron gas taking into
account the Landau damping of transverse plasmons. The Landau damping strongly
suppresses $\eta_{ee}$ in the domain of ultrarelativistic degenerate electrons
and modifies its %asymptotic temperature behavior. The efficiency of the
electron shear viscosity in the cores of white dwarfs and envelopes of neutron
stars is analyzed.",0803.3893v1
2008-04-09,Stationary Oscillations in a Damped Wave Equation from Isospectral Bessel Functions,"Using the isospectral partners of the Bessel functions derived by Reyes et
al., we find, on one hand, that these functions show non-typical supersymmetric
(SUSY) behavior and, on the other, that the isospectral partner of the
classical wave equation is equivalent to that of a damped system whose
oscillations do not vanish in time, but show a non-harmonic shape.",0804.1510v1
2008-06-03,Simulation study of fast ion instability in the ILC damping ring and PETRA III,"The fast ion instability is simulated in different gas pressures and fill
patterns for the damping ring of the International Linear Collider (ILC) and
PETRA III respectively. Beam size variation due to beta function and dispersion
function change is taken into account. Feedback is also applied in the
simulation.",0806.0529v1
2008-08-01,Damped wave equations with dynamic boundary conditions,"We discuss several classes of linear second order initial-boundary value
problems, where damping terms appear in the main wave equation as well as in
the dynamic boundary condition. We investigate their well-posedness and
describe some qualitative properties of their solutions, including boundedness,
stability, or almost periodicity. In particular, we are able to characterize
the analyticity of certain $C_0$-semigroups associated to such problems.
Applications to several problems on domains and networks are shown.",0808.0213v1
2008-12-17,The damping of gravitational waves in dust,"We examine a simple model of interaction of gravitational waves with matter
(primarily represented by dust). The aim is to investigate a possible damping
effect on the intensity of gravitational wave when passing through media. This
might be important for gravitational wave astronomy when the sources are
obscured by dust or molecular clouds.",0812.3336v1
2009-05-24,Computer assisted proof of the existence of homoclinic tangency for the Henon map and for the forced-damped pendulum,"We present a topological method for the efficient computer assisted
verification of the existence of the homoclinic tangency which unfolds
generically in a one-parameter family of planar maps. The method has been
applied to the Henon map and the forced damped pendulum ODE.",0905.3924v1
2009-08-15,"Antigravitation, Dark Energy, Dark Matter - Alternative Solution","Collisional damping of gravitational waves in the Newtonian matter is
investigated. The generalized theory of Landau damping is applied to the
gravitational physical systems in the context of the plasma gravitational
analogy.",0908.2180v3
2009-08-31,A comment about the existence of a weak solution for a non linear wave equation damped propagation,"We give a proof for the existence of a weak solution on the initial-value
problem of a non-linear damped propagation",0909.0052v2
2009-09-15,Quantum Parrondo's games under decoherence,"We study the effect of quantum noise on history dependent quantum Parrondo's
games by taking into account different noise channels. Our calculations show
that entanglement can play a crucial role in quantum Parrondo's games. It is
seen that for the maximally entangled initial state in the presence of
decoherence, the quantum phases strongly influence the payoffs for various
sequences of the game. The effect of amplitude damping channel leads to winning
payoffs. Whereas the depolarizing and phase damping channels lead to the losing
payoffs. In case of amplitude damping channel, the payoffs are enhanced in the
presence of decoherence for the sequence AAB. This is because the quantum
phases interfere constructively which leads to the quantum enhancement of the
payoffs in comparison to the undecohered case. It is also seen that the quantum
phase angles damp the payoffs significantly in the presence of decoherence.
Furthermore, it is seen that for multiple games of sequence AAB, under the
influence of amplitude damping channel, the game still remains a winning game.
However, the quantum enhancement reduces in comparison to the single game of
sequence AAB because of the destructive interference of phase dependent terms.
In case of depolarizing channel, the game becomes a loosing game. It is seen
that for the game sequence B the game is loosing one and the behavior of
sequences B and BB is similar for amplitude damping and depolarizing channels.
In addition, the repeated games of A are only influenced by the amplitude
damping channel and the game remains a losing game. Furthermore, it is also
seen that for any sequence when played in series, the phase damping channel
does not influence the game.",0909.2897v2
2009-10-01,Global attractor for weakly damped Nonlinear Schrödinger equations in $L^2(\R)$,"We prove that the weakly damped nonlinear Schr\""odinger flow in
$L^2(\mathbb{R})$ provides a dynamical system which possesses a global
attractor. The proof relies on the continuity of the Schr\""odinger flow for the
weak topology in $L^2(\R)$.",0910.0172v1
2010-01-01,Exponential Energy Decay for Damped Klein-Gordon Equation with Nonlinearities of Arbitrary Growth,"We derive a uniform exponential decay of the total energy for the nonlinear
Klein-Gordon equation with a damping around spatial infinity in the whole space
or in the exterior of a star shaped obstacle.",1001.0209v1
2010-03-10,"Covariant Constitutive Relations, Landau Damping and Non-stationary Inhomogeneous Plasmas","Models of covariant linear electromagnetic constitutive relations are
formulated that have wide applicability to the computation of susceptibility
tensors for dispersive and inhomogeneous media. A perturbative framework is
used to derive a linear constitutive relation for a globally neutral plasma
enabling one to describe in this context a generalized Landau damping mechanism
for non-stationary inhomogeneous plasma states.",1003.2062v1
2010-03-28,Damped wave dynamics for a complex Ginzburg-Landau equation with low dissipation,"We consider a complex Ginzburg-Landau equation, corresponding to a
Gross-Pitaevskii equation with a small dissipation term. We study an asymptotic
regime for long-wave perturbations of constant maps of modulus one. We show
that such solutions never vanish and we derive a damped wave dynamics for the
perturbation.",1003.5375v1
2010-06-16,Hysteresis effects in Bose-Einstein condensates,"Here, we consider damped two-components Bose-Einstein condensates with
many-body interactions. We show that, when the external trapping potential has
a double-well shape and when the nonlinear coupling factors are modulated in
time, hysteresis effects may appear under some circumstances. Such hysteresis
phenomena are a result of the joint contribution between the appearance of
saddle node bifurcations and damping effect.",1006.3240v1
2010-09-25,Different Network Topologies for Distributed Electric Damping of Beam Vibrations,"In this work passive electric damping of structural vibrations by distributed
piezoelectric transducers and electric networks is analyzed. Different
distributed electric controllers are examined as finite degrees of freedom
systems and their performances are compared. Modal reduction is used to
optimize the electric parameters",1009.5001v1
2010-12-27,The Relativistic kinetics of gravitational waves collisional damping in hot Universe,"The article is a translation of authors paper printed earlier in the
inaccessible edition and summarizing the results of research of gravitational
waves damping problem in the cosmologic plasma due to the different
interactions of elementary particles.",1012.5582v1
2011-01-14,Blowup for the Damped $L^{2}$-Critical Nonlinear Schrödinger Equation,"We consider the Cauchy problem for the $L^{2}$-critical damped nonlinear
Schr\""odinger equation. We prove existence and stability of finite time blowup
dynamics with the log-log blow-up speed for $\|\nabla u(t)\|_{L^2}$.",1101.2763v3
2011-02-05,Partial regularity of weak solutions of the viscoelastic Navier-Stokes equations with damping,"We prove an analog of the Caffarelli-Kohn-Nirenberg theorem for weak
solutions of a system of PDE that model a viscoelastic fluid in the presence of
an energy damping mechanism. The system was recently introduced as a possible
method of establishing the global in time existence of weak solutions of the
well known Oldroyd system.",1102.1112v1
2011-02-21,The One Dimensional Damped Forced Harmonic Oscillator Revisited,"In this paper we give a general solution to the problem of the damped
harmonic oscillator under the influence of an arbitrary time-dependent external
force. We employ simple methods accessible for beginners and useful for
undergraduate students and professors in an introductory course of mechanics.",1102.4112v1
2011-03-18,"Soliton complexity in the damped-driven nonlinear Schrödinger equation: stationary, periodic, quasiperiodic complexes","Stationary and oscillatory bound states, or complexes, of the damped-driven
solitons are numerically path-followed in the parameter space. We compile a
chart of the two-soliton attractors, complementing the one-soliton attractor
chart.",1103.3607v1
2011-09-27,Exponential energy decay of solutions for a system of viscoelastic wave equations of Kirchhoff type with strong damping,"The initial boundary value problem for a system of viscoelastic wave
equations of Kirchhoff type with strong damping is considered. We prove that,
under suitable assumptions on relaxation functions and certain initial data,
the decay rate of the solutions energy is exponential.",1109.5921v1
2011-12-04,On the Apparent Superluminal Motion of a Damped Gaussian Pulse,"Alicki has demonstrated that a travelling Gaussian pulse subject to damping
is indistinguishable from an undamped pulse moving with greater speed; such an
effect could create the illusion of a pulse moving faster than light. In this
note, an alternative derivation of the same result is presented. However, it is
unlikely that this particular illusion could explain the superluminal
neutrino-velocities reported by OPERA.",1112.1324v1
2011-12-28,Photon Damping in One-Loop HTL Perturbation Theory,"We determine the damping rates of slow-moving photons in next-to-leading
order hard-thermal-loop perturbation of massless QED. We find both longitudinal
and transverse rates finite, positive, and equal at zero momentum. Various
divergences, light-cone and at specific momenta, but not infrared, appear and
cancel systematically.",1112.6065v2
2012-07-31,Energy decay rates for solutions of the wave equations with nonlinear damping in exterior domain,"In this paper we study the behaviors of the energy of solutions of the wave
equations with localized nonlinear damping in exterior domains.",1207.7336v3
2012-11-02,A modified test function method for damped waves,"In this paper we use a modified test function method to derive nonexistence
results for the semilinear wave equation with time-dependent speed and damping.
The obtained critical exponent is the same exponent of some recent results on
global existence of small data solution.",1211.0453v1
2012-12-15,Damping and Pseudo-fermions,"After a short abstract introduction on the time evolution driven by non
self-adjoint hamiltonians, we show how the recently introduced concept of {\em
pseudo-fermion} can be used in the description of damping in finite dimensional
quantum systems, and we compare the results deduced adopting the Schr\""odinger
and the Heisenberg representations.",1212.3663v1
2013-01-14,On estimating the output entropy of a tensor product of the quantum phase-damping channel with an arbitrary channel,"We obtained the estimation from below for the output entropy of a tensor
product of the quantum phase-damping channel with an arbitrary channel. It is
shown that from this estimation immediately follows that the strong
superadditivity of the output entropy holds for this channel as well as for the
quantum depolarizing channel.",1301.2886v1
2013-06-10,Smooth attractors for the quintic wave equations with fractional damping,"Dissipative wave equations with critical quintic nonlinearity and damping
term involving the fractional Laplacian are considered. The additional
regularity of energy solutions is established by constructing the new
Lyapunov-type functional and based on this, the global well-posedness and
dissipativity of the energy solutions as well as the existence of a smooth
global and exponential attractors of finite Hausdorff and fractal dimension is
verified.",1306.2294v1
2013-07-20,Entanglement-assisted capacities of time-correlated amplitude-damping channel,"We calculate the information capacities of a time-correlated
amplitude-damping channel, provided the sender and receiver share prior
entanglement. Our analytical results show that the noisy channel with zero
capacity can transmit information if it has finite memory. The capacities
increase as the memory increases attaining maximum value for perfect memory
channel.",1307.5403v1
2013-07-23,Comment on Damping Force in the Transit-time Method of Optical Stochastic Cooling,"In this brief report we pointed at mistake in paper A. Zholents, Damping
Force in the Transit-Time Method of Optical Stochastic Cooling, PRLST. Mar 1,
2012. 2 pp. Published in Phys.Rev.ST Accel. Beams 15 (2012) 032801.",1307.6185v1
2013-10-28,Large deviations for a damped telegraph process,"In this paper we consider a slight generalization of the damped telegraph
process in Di Crescenzo and Martinucci (2010). We prove a large deviation
principle for this process and an asymptotic result for its level crossing
probabilities (as the level goes to infinity). Finally we compare our results
with the analogous well-known results for the standard telegraph process.",1310.7332v1
2013-10-29,Blow-up for the wave equation with nonlinear source and boundary damping terms,"The paper deals with blow--up for the solutions of wave equation with
nonlinear source and nonlinear boudary damping terms, posed in a bounded and
regular domain. The initial data are posed in the energy space. The aim of the
paper is to improve previous blow-up results concerning the problem.",1310.7734v1
2013-11-24,Global small solution to the 2D MHD system with a velocity damping term,"This paper studies the global well-posedness of the incompressible
magnetohydrodynamic (MHD) system with a velocity damping term. We establish the
global existence and uniqueness of smooth solutions when the initial data is
close to an equilibrium state. In addition, explicit large-time decay rates for
various Sobolev norms of the solutions are also given.",1311.6185v1
2014-08-25,Asymptotic behavior of global entropy solutions for nonstrictly hyperbolic systems with linear damping,"In this paper we investigate the large time behavior of the global weak
entropy solutions to the symmetric Keyftiz-Kranzer system with linear damping.
It is proved that as t tends to infinite the entropy solutions tend to zero in
the L p norm",1408.5856v1
2014-08-26,Stability of an abstract-wave equation with delay and a Kelvin-Voigt damping,"In this paper we consider a stabilization problem for the abstract-wave
equation with delay. We prove an exponential stability result for appropriate
damping coefficient. The proof of the main result is based on a
frequency-domain approach.",1408.6261v2
2015-02-02,"Spontaneous toroidal rotation, anomalous radial particle flux, and the electron-ion asymmetric anomalous viscous damping","AA spontaneous toroidal rotation due to the electron-ion asymmetric anomalous
viscous damping and the turbulent radial particle flux has been found, which
explains the experimental observation of the anomalous toroidal momentum source
in the edge of a tokamak plasma.",1502.00499v3
2015-03-06,Concentration Of Laplace Eigenfunctions And Stabilization Of Weakly Damped Wave Equation,"- In this article, we prove some universal bounds on the speed of
concentration on small (frequency-dependent) neighborhoods of submanifolds of L
2-norms of quasi modes for Laplace operators on compact manifolds. We deduce
new results on the rate of decay of weakly damped wave equations.
R{\'e}sum{\'e}.",1503.02058v1
2015-03-11,Upper bounds for the attractor dimension of damped Navier-Stokes equations in $\mathbb R^2$,"We consider finite energy solutions for the damped and driven two-dimensional
Navier--Stokes equations in the plane and show that the corresponding dynamical
system possesses a global attractor. We obtain upper bounds for its fractal
dimension when the forcing term belongs to the whole scale of homogeneous
Sobolev spaces from -1 to 1",1503.03415v1
2015-03-18,Laplace Eigenfunctions And Damped Wave Equation Ii: Product Manifolds,"- The purpose of this article is to study possible concentrations of
eigenfunc-tions of Laplace operators (or more generally quasi-modes) on product
manifolds. We show that the approach of the first author and Zworski [10, 11]
applies (modulo rescalling) and deduce new stabilization results for weakly
damped wave equations which extend to product manifolds previous results by
Leautaud-Lerner [12] obtained for products of tori.",1503.05513v1
2015-10-14,The General Solution to Vlasov Equation and Linear Landau Damping,"A general solution to linearized Vlasov equation for an electron
electrostatic wave in a homogeneous unmagnetized plasma is derived. The
quasi-linear diffusion coefficient resulting from this solution is a continuous
function of omega in contrast to that derived from the traditional Vlasov
treatment. The general solution is also equivalent to the Landau treatment of
the plasma normal oscillations, and hence leads to the well-known Landau
damping.",1510.03949v1
2016-01-13,Non uniform decay of the energy of some dissipative evolution systems,"In this paper we consider second order evolution equations with bounded
damping. We give a characterization of a non uniform decay for the damped
problem using a kind of observability estimate for the associated undamped
problem.",1601.03373v1
2016-01-27,Forward self-similar solutions to the viscoelastic Navier-Stokes equation with damping,"Motivated by \cite{JS}, we prove that there exists a global, forward
self-similar solution to the viscoelastic Navier-Stokes equation with damping,
that is smooth for $t>0$, for any initial data that is homogeneous of degree
$-1$.",1601.07478v1
2016-03-14,Phase speed and frequency-dependent damping of longitudinal intensity oscillations in coronal loop structures observed with AIA/SDO,"Longitudinal intensity oscillations along coronal loops that are interpreted
as signatures of magneto-acoustic waves are observed frequently in different
coronal structures. The aim of this paper is to estimate the physical
parameters of the slow waves and the quantitative dependence of these
parameters on their frequencies in the solar corona loops that are situated
above active regions with the Atmospheric Imaging Assembly (AIA) onboard Solar
Dynamic Observatory (SDO). The observed data on 2012-Feb-12, consisting of 300
images with an interval of 24 seconds in the 171 $\rm{\AA}$ and 193 $\rm{\AA}$
passbands is analyzed for evidence of propagating features as slow waves along
the loop structures. Signatures of longitudinal intensity oscillations that are
damped rapidly as they travel along the loop structures were found, with
periods in the range of a few minutes to few tens of minutes. Also, the
projected (apparent) phase speeds, projected damping lengths, damping times and
damping qualities of filtered intensities centred on the dominant frequencies
are measured in the range of $\rm{C_s}\simeq 38-79~ \rm {km~s^{-1}}$,
$\rm{L_d}\simeq 23-68 ~\rm{Mm }$, $\rm{\tau_d}\simeq 7- 21 ~\rm {min}$ and
$\rm{\tau_d/P}\simeq 0.34- 0.77$, respectively. The theoretical and
observational results of this study indicate that the damping times and damping
lengths increase with increasing the oscillation periods, and are highly
sensitive function of oscillation period, but the projected speeds and the
damping qualities are not very sensitive to the oscillation periods.
Furthermore, the magnitude values of physical parameters are in good agreement
with the prediction of the theoretical dispersion relations of high-frequency
MHD waves ($>1.1~ \rm{mHz}$) in a coronal plasma with electron number density
in the range of $\rm{n_e}\simeq 10^{7} - 10^{12} ~\rm{cm^{-3}}$.",1603.04207v1
2016-04-27,Critical exponent for nonlinear wave equations with frictional and viscoelastic damping terms,"In this paper, we study the Cauchy problem for a nonlinear wave equation with
frictional and viscoelastic damping terms. Our aim is to obtain the threshold,
to classify the global existence of solution for small data or the finite time
blow-up pf the solution, with respect to the growth order of the nonlinearity.",1604.08265v1
2017-02-02,Stationary solutions for stochastic damped Navier-Stokes equations in $\mathbb R^d$,"We consider the stochastic damped Navier-Stokes equations in $\mathbb R^d$
($d=2,3$), assuming as in our previous work [4] that the covariance of the
noise is not too regular, so It\^o calculus cannot be applied in the space of
finite energy vector fields. We prove the existence of an invariant measure
when $d=2$ and of a stationary solution when $d=3$.",1702.00697v1
2017-03-08,Moderate deviations for the Langevin equation with strong damping,"In this paper, we establish a moderate deviations principle for the Langevin
dynamics with strong damping. The weak convergence approach plays an important
role in the proof.",1703.03033v3
2017-03-17,Damping in a Superconducting Mechanical Resonator,"We study a mechanical resonator made of aluminum near the normal to super
conductivity phase transition. A sharp drop in the rate of mechanical damping
is observed below the critical temperature. The experimental results are
compared with predictions based on the Bardeen Cooper Schrieffer theory of
superconductivity and a fair agreement is obtained.",1703.05912v1
2017-03-27,On the $L^{2}$-critical nonlinear Schrodinger equation with an inhomogeneous damping term,"We consider the $L^2$-critical nonlinear Schrodinger equation with an
inhomogeneous damping term. We prove that there exists an initial data such
that the corresponding solution is global in $H^1(R^d)$ and we give the minimal
time of the blow up for some initial data.",1703.09101v1
2017-08-11,Global existence of a diffusion limit with damping for the compressible radiative Euler system coupled to an electromagnetic field,"We study the Cauchy problem for a system of equations corresponding to a
singular limit of radiative hydrodynamics, namely the 3D radiative compressible
Euler system coupled to an electromagnetic field through the MHD approximation.
Assuming the presence of damping together with suitable smallness hypotheses
for the data, we prove that this problem admits a unique global smooth
solution.",1708.03681v1
2017-08-21,A remark on the critical exponent for the semilinear damped wave equation on the half-space,"In this short notice, we prove the non-existence of global solutions to the
semilinear damped wave equation on the half-space, and we determine the
critical exponent for any space dimension.",1708.06429v1
2017-08-24,Nonlinear network dynamics for interconnected micro-grids,"This paper deals with transient stability in interconnected micro-grids. The
main contribution involves i) robust classification of transient dynamics for
different intervals of the micro-grid parameters (synchronization, inertia, and
damping); ii) exploration of the analogies with consensus dynamics and bounds
on the damping coefficient separating underdamped and overdamped dynamics iii)
the extension to the case of disturbed measurements due to hackering or
parameter uncertainties.",1708.07296v1
2018-11-07,Statistical complexity of the quasiperiodical damped systems,"We consider the concept of statistical complexity to write the
quasiperiodical damped systems applying the snapshot attractors. This allows us
to understand the behaviour of these dynamical systems by the probability
distribution of the time series making a difference between the regular, random
and structural complexity on finite measurements. We interpreted the
statistical complexity on snapshot attractor and determined it on the
quasiperiodical forced pendulum.",1811.02958v1
2019-05-01,Dissipative structure and diffusion phenomena for doubly dissipative elastic waves in two space dimensions,"In this paper we study the Cauchy problem for doubly dissipative elastic
waves in two space dimensions, where the damping terms consist of two different
friction or structural damping. We derive energy estimates and diffusion
phenomena with different assumptions on initial data. Particularly, we find the
dominant influence on diffusion phenomena by introducing a new threshold of
diffusion structure.",1905.00257v1
2020-07-30,Delta shock solution to the generalized one-dimensional zero-pressure gas dynamics system with linear damping,"In this paper, we propose a time-dependent viscous system and by using the
vanishing viscosity method we show the existence of delta shock solution for a
particular $2 \times 2$ system of conservation laws with linear damping.",2007.15184v2
2013-08-23,Stability results for second-order evolution equations with switching time-delay,"We consider second-order evolution equations in an abstract setting with
intermittently delayed/ not-delayed damping. We give sufficient conditions for
asymptotic and exponential stability, improving and generalising our previous
results from [19]. In particular, under suitable conditions, we can consider
unbounded damping operators. Some concrete examples are finally presented.",1308.5100v1
2016-11-27,Nonlinear Wave Equation with Damping: Periodic Forcing and Non-Resonant Solutions to the Kuznetsov Equation,"Existence of non-resonant solutions of time-periodic type are established for
the Kuznetsov equation with a periodic forcing term. The equation is considered
in a three-dimensional whole-space, half-space and bounded domain, and with
both non-homogeneous Dirichlet and Neumann boundary values. A method based on
Lp estimates of the corresponding linearization, namely the wave equation with
Kelvin-Voigt damping, is employed.",1611.08883v1
2009-12-11,"Waves, damped wave and observation","We consider the wave equation in a bounded domain (eventually convex). Two
kinds of inequality are described when occurs trapped ray. Applications to
control theory are given. First, we link such kind of estimate with the damped
wave equation and its decay rate. Next, we describe the design of an
approximate control function by an iterative time reversal method.",0912.2202v1
2011-11-20,Null controllability of the structurally damped wave equation with moving point control,"We investigate the internal controllability of the wave equation with
structural damping on the one dimensional torus. We assume that the control is
acting on a moving point or on a moving small interval with a constant
velocity. We prove that the null controllability holds in some suitable Sobolev
space and after a fixed positive time independent of the initial conditions.",1111.4655v1
2012-04-06,Late time evolution of the gravitational wave damping in the early Universe,"An analytical solution for time evolution of the gravitational wave damping
in the early Universe due to freely streaming neutrinos is found in the late
time regime. The solution is represented by a convergent series of spherical
Bessel functions of even order and was possible with the help of a new compact
formula for the convolution of spherical Bessel functions of integer order.",1204.1384v2
2013-09-10,Convergence of global solutions for some classes of nonlinear damped wave equations,"We consider the asymptotic behavior of the soltion to the wave equation with
time-dependent damping and analytic nonlinearity. Our main goal is to prove the
convergence of a global solution to an equilibrium as time goes to infinity by
means of a suitable Lojasiewicz-Simon type inequality.",1309.2364v1
2013-09-13,On diffusion phenomena for the linear wave equation with space-dependent damping,"In this paper, we prove the diffusion phenomenon for the linear wave equation
with space-dependent damping. We prove that the asymptotic profile of the
solution is given by a solution of the corresponding heat equation in the
$L^2$-sense.",1309.3377v1
2013-09-19,Compressible Euler equation with damping on Torus in arbitrary dimensions,"We study the exponential stability of constant steady state of isentropic
compressible Euler equation with damping on $\mathbb T^n$. The local existence
of solutions is based on semigroup theory and some commutator estimates. We
propose a new method instead of energy estimates to study the stability, which
works equally well for any spatial dimensions.",1309.5059v3
2016-05-19,On circular flows: linear stability and damping,"In this article we establish linear inviscid damping with optimal decay rates
around 2D Taylor-Couette flow and similar monotone flows in an annular domain
$B_{r_{2}}(0) \setminus B_{r_{1}}(0) \subset \mathbb{R}^{2}$. Following recent
results by Wei, Zhang and Zhao, we establish stability in weighted norms, which
allow for a singularity formation at the boundary, and additional provide a
description of the blow-up behavior.",1605.05959v1
2016-08-04,Resonance Damping of the THz-frequency Transverse Acoustic Phonon in the Relaxor Ferroelectric KTa1-xNbxO3,"The damping ($\Gamma_a$) of the transverse acoustic (TA) phonon in single
crystals of the relaxor $KTa_{1-x}Nb_xO_3$ with x=0.15-0.17 was studied by
means of high resolution inelastic cold neutron scattering near the (200) B.Z.
point where diffuse scattering is absent, although it is present near (110). In
a wide range of temperatures centered on the phase transition, T=195K-108K, the
TA phonon width (damping) exhibits a step increase around momentum q=0.07, goes
through a shallow maximum at q=0.09-0.12 and remains high up to the highest
momentum studied of q=0.16. These experimental results are explained in terms
of a resonant interaction between the TA phonon and the collective or
correlated reorientation through tunneling of the off-center Nb+5 ions. The
observed TA damping is successfully reproduced in a simple model that includes
an interaction between the TA phonon and a dispersionless localized mode (LM)
with frequency $\omega_L$ and damping $\Gamma_L$ ($\Gamma_L < \omega_L$),
itself coupled to the transverse optic (TO) mode. Maximum damping of the TA
phonon occurs when its frequency $\omega_a \approx{\omega_L}$. $\omega_L$ and
$\Gamma_L$ are moderately dependent on temperature but the oscillator strength,
$M_2$, of the resonant damping exhibits a strong maximum in the range
$T\sim{150 K-120 K}$ in which neutron diffuse scattering near the (110) B.Z.
point is also maximum and the dielectric susceptibility exhibits the relaxor
behavior. The maximum value of M appears to be due to the increasing number of
polar nanodomains. In support of the proposed model, the observed value of
$\omega_L$ is found to be similar to the estimate previously obtained by
Girshberg and Yacoby. Alternatively, the TA phonon damping can be successfully
fitted in the framework of an empirical Havriliak - Negami (HN) relaxation
model that includes a strong resonance-like transient contribution.",1608.01591v1
2016-08-26,Cheillini integrability and quadratically damped oscillators,"In this paper a new approach to study an equation of the Lienard type with a
strong quadratic damping is proposed based on Jacobi's last multiplier and
Cheillini's integrability condition. We obtain a closed form solution of the
transcendental characteristic equation of the Lienard type equation using the
Lambert W-function.",1608.07377v1
2017-06-22,Asymptotic profile of solutions for some wave equations with very strong structural damping,"We consider the Cauchy problem in R^n for some types of damped wave
equations. We derive asymptotic profiles of solutions with weighted
L^{1,1}(R^n) initial data by employing a simple method introduced by the first
author. The obtained results will include regularity loss type estimates, which
are essentially new in this kind of equations.",1706.07174v1
2017-12-04,Radiative seesaw models linking to dark matter candidates inspired by the DAMPE excess,"We propose two possibilities to explain an excess of electron/positron flux
around 1.4 TeV recently reported by Dark Matter Explore (DAMPE) in the
framework of radiative seesaw models where one of them provides a fermionic
dark matter candidate, and the other one provides a bosonic dark matter
candidate. We also show unique features of both models regarding neutrino mass
structure.",1712.00941v1
2018-01-06,Multiscale analysis of semilinear damped stochastic wave equations,"In this paper we proceed with the multiscale analysis of semilinear damped
stochastic wave motions. The analysis is made by combining the well-known sigma
convergence method with its stochastic counterpart, associated to some
compactness results such as the Prokhorov and Skorokhod theorems. We derive the
equivalent model, which is of the same type as the micro-model.",1801.02036v1
2018-09-22,Asymptotic behavior of solutions to 3D incompressible Navier-Stokes equations with damping,"In this paper, we study the upper bound of the time decay rate of solutions
to the Navier-Stokes equations and generalized Navier-Stokes equations with
damping term $|u|^{\beta-1}u$ ($\beta>1$) in $\mathbb{R}^3$.",1809.08394v2
2018-10-22,Optimal leading term of solutions to wave equations with strong damping terms,"We analyze the asymptotic behavior of solutions to wave equations with strong
damping terms. If the initial data belong to suitable weighted $L^1$ spaces,
lower bounds for the difference between the solutions and the leading terms in
the Fourier space are obtained, which implies the optimality of expanding
methods and some estimates proposed in this paper.",1810.09114v1
2018-10-29,Apples with Apples comparison of 3+1 conformal numerical relativity schemes,"This paper contains a comprehensive comparison catalog of `Apples with
Apples' tests for the BSSNOK, CCZ4 and Z4c numerical relativity schemes, with
and without constraint damping terms for the latter two. We use basic numerical
methods and reach the same level of accuracy as existing results in the
literature. We find that the best behaving scheme is generically CCZ4 with
constraint damping terms.",1810.12346v1
2019-06-21,Unique determination of the damping coefficient in the wave equation using point source and receiver data,"In this article, we consider the inverse problems of determining the damping
coefficient appearing in the wave equation. We prove the unique determination
of the coefficient from the data coming from a single coincident
source-receiver pair. Since our problem is under-determined, so some extra
assumption on the coefficient is required to prove the uniqueness.",1906.08987v1
2019-07-12,Non-Existence of Periodic Orbits for Forced-Damped Potential Systems in Bounded Domains,"We prove Lr-estimates on periodic solutions of periodically-forced,
linearly-damped mechanical systems with polynomially-bounded potentials. The
estimates are applied to obtain a non-existence result of periodic solutions in
bounded domains, depending on an upper bound on the gradient of the potential.
The results are illustrated on examples.",1907.05778v1
2019-09-02,On the inclusion of damping terms in the hyperbolic MBO algorithm,"The hyperbolic MBO is a threshold dynamic algorithm which approximates
interfacial motion by hyperbolic mean curvature flow. We introduce a
generalization of this algorithm for imparting damping terms onto the equation
of motion. We also construct corresponding numerical methods, and perform
numerical tests. We also use our results to show that the generalized
hyperbolic MBO is able to approximate motion by the standard mean curvature
flow.",1909.00552v1
2019-09-07,Lindblad dynamics of the damped and forced quantum harmonic oscillator: General solution,"The quantum dynamics of a damped and forced harmonic oscillator described by
a Lindblad master equation is analyzed. The master equation is converted into a
matrix-vector representation and the resulting non-Hermitian Schr\""odinger
equation is solved by Lie-algebraic techniques allowing the construction of the
general solution for the density operator.",1909.03206v1
2019-10-17,Modified different nonlinearities for weakly coupled systems of semilinear effectively damped waves with different time-dependent coefficients in the dissipation terms,"We prove the global existence of small data solution in all space dimension
for weakly coupled systems of semi-linear effectively damped wave, with
different time-dependent coefficients in the dissipation terms. Moreover,
nonlinearity terms $ f(t,u) $ and $ g(t,v) $ satisfying some properties of the
parabolic equation. We study the problem in several classes of regularity.",1910.07731v1
2020-01-23,Nonlinear inviscid damping for a class of monotone shear flows in finite channel,"We prove the nonlinear inviscid damping for a class of monotone shear flows
in $T\times [0,1]$ for initial perturbation in Gevrey-$1/s$($s>2$) class with
compact support. The main idea of the proof is to use the wave operator of a
slightly modified Rayleigh operator in a well chosen coordinate system.",2001.08564v1
2020-02-26,Bistability in the dissipative quantum systems I: Damped and driven nonlinear oscillator,"We revisit quantum dynamics of the damped and driven nonlinear oscillator. In
the classical case this system has two stationary solutions (the limit cycles)
in the certain parameter region, which is the origin of the celebrated
bistability phenomenon. The quantum-classical correspondence for the oscillator
dynamics is discussed in details.",2002.11373v1
2020-04-08,Scattering and asymptotic order for the wave equations with the scale-invariant damping and mass,"We consider the linear wave equation with the time-dependent scale-invariant
damping and mass. We also treat the corresponding equation with the energy
critical nonlinearity. Our aim is to show that the solution scatters to a
modified linear wave solution and to obtain its asymptotic order.",2004.03832v2
2020-04-24,Infinite energy solutions for weakly damped quintic wave equations in $\mathbb{R}^3$,"The paper gives a comprehensive study of infinite-energy solutions and their
long-time behavior for semi-linear weakly damped wave equations in
$\mathbb{R}^3$ with quintic nonlinearities. This study includes global
well-posedness of the so-called Shatah-Struwe solutions, their dissipativity,
the existence of a locally compact global attractors (in the uniformly local
phase spaces) and their extra regularity.",2004.11864v1
2020-12-13,Uniform Stabilization of the Petrovsky-Wave Nonlinear coupled system with strong damping,"This paper concerns the well-posedness and uniform stabilization of the
Petrovsky-Wave Nonlinear coupled system with strong damping. Existence of
global weak solutions for this problem is established by using the Galerkin
method. Meanwhile, under a clever use of the multiplier method, we estimate the
total energy decay rate.",2012.07109v3
2012-05-30,Beam Dynamics Studies for the CLIC Main Linac,"The implications of long-range wakefields on the beam quality are
investigated through a detailed beam dynamics study. Injection offsets are
considered and the resulting emittance dilution recorded, including systematic
sources of error. These simulations have been conducted for damped and detuned
structures (DDS) and for waveguide damped structures-both for the CLIC
collider.",1205.6623v2
2018-07-06,Global existence for the 3-D semilinear damped wave equations in the scattering case,"We study the global existence of solutions to semilinear damped wave
equations in the scattering case with derivative power-type nonlinearity on
(1+3) dimensional nontrapping asymptotically Euclidean manifolds. The main idea
is to exploit local energy estimate, together with local existence to convert
the parameter $\mu$ to small one.",1807.02403v1
2018-12-13,Rapid exponential stabilization of a 1-D transmission wave equation with in-domain anti-damping,"We consider the problem of pointwise stabilization of a one-dimensional wave
equation with an internal spatially varying anti-damping term. We design a
feedback law based on the backstepping method and prove exponential stability
of the closed-loop system with a desired decay rate.",1812.11035v1
2019-01-20,Stationary Solutions of Damped Stochastic 2-dimensional Euler's Equation,"Existence of stationary point vortices solution to the damped and
stochastically driven Euler's equation on the two dimensional torus is proved,
by taking limits of solutions with finitely many vortices. A central limit
scaling is used to show in a similar manner the existence of stationary
solutions with white noise marginals.",1901.06744v1
2019-03-13,Solar $p$-mode damping rates: insight from a 3D hydrodynamical simulation,"Space-borne missions CoRoT and Kepler have provided a rich harvest of
high-quality photometric data for solar-like pulsators. It is now possible to
measure damping rates for hundreds of main-sequence and thousands of red-giant.
However, among the seismic parameters, mode damping rates remain poorly
understood and thus barely used for inferring the physical properties of stars.
Previous approaches to model mode damping rates were based on mixing-length
theory or a Reynolds-stress approach to model turbulent convection. While able
to grasp the main physics of the problem, those approaches are of little help
to provide quantitative estimates as well as a definitive answer on the
relative contribution of each physical mechanism. Our aim is thus to assess the
ability of 3D hydrodynamical simulations to infer the physical mechanisms
responsible for damping of solar-like oscillations. To this end, a solar
high-spatial resolution and long-duration hydrodynamical 3D simulation computed
with the ANTARES code allows probing the coupling between turbulent convection
and the normal modes of the simulated box. Indeed, normal modes of the
simulation experience realistic driving and damping in the super-adiabatic
layers of the simulation. Therefore, investigating the properties of the normal
modes in the simulation provides a unique insight into the mode physics. We
demonstrate that such an approach provides constraints on the solar damping
rates and is able to disentangle the relative contribution related to the
perturbation of the turbulent pressure, the gas pressure, the radiative flux,
and the convective flux contributions. Finally, we conclude that using the
normal modes of a 3D numerical simulation is possible and is potentially able
to unveil the respective role of the different physical mechanisms responsible
for mode damping provided the time-duration of the simulation is long enough.",1903.05479v1
2019-04-15,Carleman estimate for an adjoint of a damped beam equation and an application to null controllability,"In this article we consider a control problem of a linear Euler-Bernoulli
damped beam equation with potential in dimension one with periodic boundary
conditions. We derive a new Carleman estimate for an adjoint of the equation
under consideration. Then using a well known duality argument we obtain
explicitly the control function which can be used to drive the solution
trajectory of the control problem to zero state.",1904.07038v1
2019-11-01,Convergence of a damped Newton's method for discrete Monge-Ampere functions with a prescribed asymptotic cone,"We prove the convergence of a damped Newton's method for the nonlinear system
resulting from a discretization of the second boundary value problem for the
Monge-Ampere equation. The boundary condition is enforced through the use of
the notion of asymptotic cone. The differential operator is discretized based
on a partial discrete analogue of the subdifferential.",1911.00260v2
2019-12-17,"Comment on ""On the Origin of Frictional Energy Dissipation""","In their interesting study (Ref. [1]) Hu et al have shown that for a simple
""harmonium"" solid model the slip-induced motion of surface atoms is close to
critically damped. This result is in fact well known from studies of
vibrational damping of atoms and molecules at surfaces. However, for real
practical cases the situation may be much more complex and the conclusions of
Hu et al invalid.",1912.07799v1
2020-08-06,On global attractors for 2D damped driven nonlinear Schrödinger equations,"Well-posedness and global attractor are established for 2D damped driven
nonlinear Schr\""odinger equation with almost periodic pumping in a bounded
region. The key role is played by a novel application of the energy equation.",2008.02741v1
2020-08-30,Influence of dissipation on extreme oscillations of a forced anharmonic oscillator,"Dynamics of a periodically forced anharmonic oscillator (AO) with cubic
nonlinearity, linear damping, and nonlinear damping, is studied. To begin with,
the authors examine the dynamics of an AO. Due to this symmetric nature, the
system has two neutrally stable elliptic equilibrium points in positive and
negative potential-wells. Hence, the unforced system can exhibit both
single-well and double-well periodic oscillations depending on the initial
conditions. Next, the authors include nonlinear damping into the system. Then,
the symmetry of the system is broken instantly and the stability of the two
elliptic points is altered to result in stable focus and unstable focus in the
positive and negative potential-wells, respectively. Consequently, the system
is dual-natured and is either non-dissipative or dissipative, depending on
location in the phase space. Furthermore, when one includes a periodic external
forcing with suitable parameter values into the nonlinearly damped AO system
and starts to increase the damping strength, the symmetry of the system is not
broken right away, but it occurs after the damping reaches a threshold value.
As a result, the system undergoes a transition from double-well chaotic
oscillations to single-well chaos mediated through extreme events (EEs).
Furthermore, it is found that the large-amplitude oscillations developed in the
system are completely eliminated if one incorporates linear damping into the
system. The numerically calculated results are in good agreement with the
theoretically obtained results on the basis of Melnikov's function. Further, it
is demonstrated that when one includes linear damping into the system, this
system has a dissipative nature throughout the entire phase space of the
system. This is believed to be the key to the elimination of EEs.",2008.13172v1
2020-09-16,Exponential decay for semilinear wave equations with viscoelastic damping and delay feedback,"In this paper we study a class of semilinear wave type equations with
viscoelastic damping and delay feedback with time variable coefficient. By
combining semigroup arguments, careful energy estimates and an iterative
approach we are able to prove, under suitable assumptions, a well-posedness
result and an exponential decay estimate for solutions corresponding to small
initial data. This extends and concludes the analysis initiated in [16] and
then developed in [13, 17].",2009.07777v1
2020-09-18,Vanishing viscosity limit for Riemann solutions to a $2 \times 2$ hyperbolic system with linear damping,"In this paper, we propose a time-dependent viscous system and by using the
vanishing viscosity method we show the existence of %delta shock solution
solutions for the Riemann problem to a particular $2 \times 2$ system of
conservation laws with linear damping.",2009.09041v1
2020-11-28,A Smoluchowski-Kramers approximation for an infinite dimensional system with state-dependent damping,"We study the validity of a Smoluchowski-Kramers approximation for a class of
wave equations in a bounded domain of $\mathbb{R}^n$ subject to a
state-dependent damping and perturbed by a multiplicative noise. We prove that
in the small mass limit the solution converges to the solution of a stochastic
quasilinear parabolic equation where a noise-induced extra drift is created.",2011.14236v2
2021-03-24,"On the long-time statistical behavior of smooth solutions of the weakly damped, stochastically-driven KdV equation","This paper considers the damped periodic Korteweg-de Vries (KdV) equation in
the presence of a white-in-time and spatially smooth stochastic source term and
studies the long-time behavior of solutions. We show that the integrals of
motion for KdV can be exploited to prove regularity and ergodic properties of
invariant measures for damped stochastic KdV. First, by considering non-trivial
modifications of the integrals of motion, we establish Lyapunov structure by
proving that moments of Sobolev norms of solutions at all orders of regularity
are bounded globally-in-time; existence of invariant measures follows as an
immediate consequence. Next, we prove a weak Foias-Prodi type estimate for
damped stochastic KdV, for which the synchronization occurs in expected value.
This estimate plays a crucial role throughout our subsequent analysis. As a
first novel application, we combine the Foias-Prodi estimate with the Lyapunov
structure to establish that invariant measures are supported on $C^\infty$
functions provided that the external driving forces belong to $C^\infty$. We
then establish ergodic properties of invariant measures, treating the regimes
of arbitrary damping and large damping separately. For arbitrary damping, we
demonstrate that the framework of `asymptotic coupling' can be implemented for
a compact proof of uniqueness of the invariant measure provided that
sufficiently many directions in phase space are stochastically forced. Our
proof is paradigmatic for SPDEs for which a weak Foias-Prodi type property
holds. Lastly, for large damping, we establish the existence of a spectral gap
with respect to a Wasserstein-like distance, and exponential mixing and
uniqueness of the invariant measure follows.",2103.12942v2
2021-04-21,On absorbing set for 3D Maxwell--Schrödinger damped driven equations in bounded region,"We consider the 3D damped driven Maxwell--Schr\""odinger equations in a
bounded region under suitable boundary conditions. We establish new a priori
estimates, which provide the existence of global finite energy weak solutions
and bounded absorbing set. The proofs rely on the Sobolev type estimates for
magnetic Schr\""odinger operator.",2104.10723v1
2021-06-23,Pitt inequality for the linear structurally damped $σ$-evolution equations,"This work is devoted to improve the time decay estimates for the solution and
some of its derivatives of the linear structurally damped $\sigma$-evolution
equations. The Pitt inequality is the main tool provided that the initial data
lies in some weighted spaces.",2106.12342v1
2021-07-22,Dimension estimates for the attractor of the regularized damped Euler equations on the sphere,"We prove existence of the global attractor of the damped and driven
Euler--Bardina equations on the 2D sphere and on arbitrary domains on the
sphere
  and give explicit estimates of its fractal dimension in terms of the physical
parameters.",2107.10779v1
2021-09-22,State-space representation of Matérn and Damped Simple Harmonic Oscillator Gaussian processes,"Gaussian processes (GPs) are used widely in the analysis of astronomical time
series. GPs with rational spectral densities have state-space representations
which allow O(n) evaluation of the likelihood. We calculate analytic state
space representations for the damped simple harmonic oscillator and the
Mat\'ern 1/2, 3/2 and 5/2 processes.",2109.10685v1
2021-10-10,Global existence of solutions for semilinear damped wave equations with variable coefficients,"We consider the Cauchy problem for the damped wave equations with variable
coefficients a(x) having power type nonlinearity |u|^p. We discuss the global
existence of solutions for small initial data and investigate the relation
between the range of a(x) and the order p.",2110.04718v2
2021-10-21,Stability properties of dissipative evolution equations with nonautonomous and nonlinear damping,"In this paper, we obtain some stability results of (abstract) dissipative
evolution equations with a nonautonomous and nonlinear damping using the
exponential stability of the retrograde problem with a linear and autonomous
feedback and a comparison principle. We then illustrate our abstract statements
for different concrete examples, where new results are achieved. In a
preliminary step, we prove some well-posedness results for some nonlinear and
nonautonomous evolution equations.",2110.11122v1
2021-11-23,Logistic damping effect in chemotaxis models with density-suppressed motility,"This paper is concerned with a parabolic-elliptic chemotaxis model with
density-suppressed motility and general logistic source in an $n$-dimensional
smooth bounded domain with Neumann boundary conditions. Under the minimal
conditions for the density-suppressed motility function, we explore how strong
the logistic damping can warrant the global boundedness of solutions, and
further establish the asymptotic behavior of solutions on top of the
conditions.",2111.11669v1
2022-01-04,Global existence and decay estimates for a viscoelastic plate equation with nonlinear damping and logarithmic nonlinearity,"In this article, we consider a viscoelastic plate equation with a logarithmic
nonlinearity in the presence of nonlinear frictional damping term. Using the
the Faedo-Galerkin method we establish the global existence of the solution of
the problem and we also prove few general decay rate results.",2201.00983v1
2022-01-20,Long Time Decay of Leray Solution of 3D-NSE With Damping,"In \cite{CJ}, the authors show that the Cauchy problem of the Navier-Stokes
equations with damping $\alpha|u|^{\beta-1}u(\alpha>0,\;\beta\geq1)$ has global
weak solutions in $L^2(\R^3)$. In this paper, we prove the uniqueness, the
continuity in $L^2$ for $\beta>3$, also the large time decay is proved for
$\beta\geq\frac{10}3$. Fourier analysis and standard techniques are used.",2201.08427v1
2022-02-20,On a non local non-homogeneous fractional Timoshenko system with frictional and viscoelastic damping terms,"We are devoted to the study of a nonhomogeneous time-fractional Timoshenko
system with frictional and viscoelastic damping terms. We are concerned with
the well-posedness of the given problem. The approach relies on some
functional-analysis tools, operator theory, a prori estimates, and density
arguments.",2202.09879v1
2022-04-05,Large time behavior of solutions to nonlinear beam equations,"In this note we analyze the large time behavior of solutions to a class of
initial/boundary problems involving a damped nonlinear beam equation. We show
that under mild conditions on the damping term of the equation of motions the
solutions of the dynamical problem converge to the solution of the stationary
problem. We also show that this convergence is exponential.",2204.02151v1
2022-05-09,Energy asymptotics for the strongly damped Klein-Gordon equation,"We consider the strongly damped Klein Gordon equation for defocusing
nonlinearity and we study the asymptotic behaviour of the energy for periodic
solutions. We prove first the exponential decay to zero for zero mean
solutions. Then, we characterize the limit of the energy, when the time tends
to infinity, for solutions with small enough initial data and we finally prove
that such limit is not necessary zero.",2205.04205v1
2022-06-07,Asymptotic study of Leray Solution of 3D-NSE With Exponential Damping,"We study the uniqueness, the continuity in $L^2$ and the large time decay for
the Leray solutions of the $3D$ incompressible Navier-Stokes equations with the
nonlinear exponential damping term $a (e^{b |u|^{\bf 2}}-1)u$, ($a,b>0$)
studied by the second author in \cite{J1}.",2206.03138v1
2022-06-25,"Decay estimate in a viscoelastic plate equation with past history, nonlinear damping, and logarithmic nonlinearity","In this article, we consider a viscoelastic plate equation with past history,
nonlinear damping, and logarithmic nonlinearity. We prove explicit and general
decay rate results of the solution to the viscoelastic plate equation with past
history. Convex properties, logarithmic inequalities, and generalised Young's
inequality are mainly used to prove the decay estimate.",2206.12561v1
2022-06-30,Effect of a viscous fluid shell on the propagation of gravitational waves,"In this paper we show that there are circumstances in which the damping of
gravitational waves (GWs) propagating through a viscous fluid can be highly
significant; in particular, this applies to Core Collapse Supernovae (CCSNe).
In previous work, we used linearized perturbations on a fixed background within
the Bondi-Sachs formalism, to determine the effect of a dust shell on GW
propagation. Here, we start with the (previously found) velocity field of the
matter, and use it to determine the shear tensor of the fluid flow. Then, for a
viscous fluid, the energy dissipated is calculated, leading to an equation for
GW damping. It is found that the damping effect agrees with previous results
when the wavelength $\lambda$ is much smaller than the radius $r_i$ of the
matter shell; but if $\lambda\gg r_i$, then the damping effect is greatly
increased.
  Next, the paper discusses an astrophysical application, CCSNe. There are
several different physical processes that generate GWs, and many models have
been presented in the literature. The damping effect thus needs to be evaluated
with each of the parameters $\lambda,r_i$ and the coefficient of shear
viscosity $\eta$, having a range of values. It is found that in most cases
there will be significant damping, and in some cases that it is almost
complete.
  We also consider the effect of viscous damping on primordial gravitational
waves (pGWs) generated during inflation in the early Universe. Two cases are
investigated where the wavelength is either much shorter than the shell radii
or much longer; we find that there are conditions that will produce significant
damping, to the extent that the waves would not be detectable.",2206.15103v2
2022-09-07,Blow up and lifespan estimates for systems of semi-linear wave equations with dampings and potentials,"In this paper, we consider the semi-linear wave systems with
power-nonlinearities and space-dependent dampings and potentials. We obtain the
blow-up regions for three types wave systems as well as the lifespan estimates.",2209.02920v1
2022-12-04,Inverse problem of recovering the time-dependent damping and nonlinear terms for wave equations,"In this paper, we consider the inverse boundary problems of recovering the
time-dependent nonlinearity and damping term for a semilinear wave equation on
a Riemannian manifold. The Carleman estimate and the construction of Gaussian
beams together with the higher order linearization are respectively used to
derive the uniqueness results of recovering the coefficients.",2212.01815v2
2022-12-14,Gevrey regularity for the Euler-Bernoulli beam equation with localized structural damping,"We study a Euler-Bernoulli beam equation with localized discontinuous
structural damping. As our main result, we prove that the associated
$C_0$-semigroup $(S(t))_{t\geq0}$ is of Gevrey class $\delta>24$ for $t>0$,
hence immediately differentiable. Moreover, we show that $(S(t))_{t\geq0}$ is
exponentially stable.",2212.07110v1
2022-12-28,On extended lifespan for 1d damped wave equation,"In this manuscript, a sharp lifespan estimate of solutions to semilinear
classical damped wave equation is investigated in one dimensional case, when
the sum of initial position and speed is $0$ pointwisely. Especially, an
extension of lifespan is shown in this case. Moreover, existence of some global
solutions are obtained by a direct computation.",2212.13845v1
2023-02-06,Uniform stabilization of an acoustic system,"We study the problem of stabilization for the acoustic system with a
spatially distributed damping. With imposing hypothesis on the structural
properties of the damping term, we identify exponential decay of solutions with
growing time.",2302.02726v1
2023-04-23,Decay rates for a variable-coefficient wave equation with nonlinear time-dependent damping,"In this paper, a class of variable-coefficient wave equations equipped with
time-dependent damping and the nonlinear source is considered. We show that the
total energy of the system decays to zero with an explicit and precise decay
rate estimate under different assumptions on the feedback with the help of the
method of weighted energy integral.",2304.11522v1
2023-05-22,Fast energy decay for wave equation with a monotone potential and an effective damping,"We consider the total energy decay of the Cauchy problem for wave equations
with a potential and an effective damping. We treat it in the whole
one-dimensional Euclidean space. Fast energy decay is established with the help
of potential. The proofs of main results rely on a multiplier method and
modified techniques adopted in [8].",2305.12666v1
2023-08-03,Blow-up for semilinear wave equations with damping and potential in high dimensional Schwarzschild spacetime,"In this work, we study the blow up results to power-type semilinear wave
equation in the high dimensional Schwarzschild spacetime, with damping and
potential terms. We can obtain the upper bound estimates of lifespan without
the assumption that the support of the initial date should be far away from the
black hole.",2308.01691v1
2023-08-22,Lifespan estimates for 1d damped wave equation with zero moment initial data,"In this manuscript, a sharp lifespan estimate of solutions to semilinear
classical damped wave equation is investigated in one dimensional case when the
Fourier 0th moment of sum of initial position and speed is $0$. Especially, it
is shown that the behavior of lifespan changes with $p=3/2$ with respect to the
size of the initial data.",2308.11113v1
2023-09-01,Damped Euler system with attractive Riesz interaction forces,"We consider the barotropic Euler equations with pairwise attractive Riesz
interactions and linear velocity damping in the periodic domain. We establish
the global-in-time well-posedness theory for the system near an equilibrium
state. We also analyze the large-time behavior of solutions showing the
exponential rate of convergence toward the equilibrium state as time goes to
infinity.",2309.00210v1
2023-10-02,The damped wave equation and associated polymer,"Considering the damped wave equation with a Gaussian noise $F$ where $F$ is
white in time and has a covariance function depending on spatial variables, we
will see that this equation has a mild solution which is stationary in time
$t$. We define a weakly self-avoiding polymer with intrinsic length $J$
associated to this SPDE. Our main result is that the polymer has an effective
radius of approximately $J^{5/3}$.",2310.01631v1
2023-10-17,Indirect boundary stabilization for weakly coupled degenerate wave equations under fractional damping,"In this paper, we consider the well-posedness and stability of a
one-dimensional system of degenerate wave equations coupled via zero order
terms with one boundary fractional damping acting on one end only. We prove
optimal polynomial energy decay rate of order $1/t^{(3-\tau)}$. The method is
based on the frequency domain approach combined with multiplier technique.",2310.11174v1
2024-03-11,Uniform estimates for solutions of nonlinear focusing damped wave equations,"For a damped wave (or Klein-Gordon) equation on a bounded domain, with a
focusing power-like nonlinearity satisfying some growth conditions, we prove
that a global solution is bounded in the energy space, uniformly in time. Our
result applies in particular to the case of a cubic equation on a bounded
domain of dimension 3.",2403.06541v1
1999-07-06,Constraints on the bulk Lorentz factor in the internal shock scenario for gamma-ray bursts,"We investigate, independently of specific emission models, the constraints on
the value of the bulk Lorentz factor Gamma of a fireball. We assume that the
burst emission comes from internal shocks in a region transparent to Thomson
scattering and before deceleration due to the swept up external matter is
effective. We consider the role of Compton drag in decelerating fast moving
shells before they interact with slower ones, thus limiting the possible
differences in bulk Lorentz factor of shells. Tighter constraints on the
possible range of Gamma are derived by requiring that the internal shocks
transform more than a few per cent of the bulk energy into radiation. Efficient
bursts may require a hierarchical scenario, where a shell undergoes multiple
interactions with other shells. We conclude that fireballs with average Lorentz
factors larger than 1000 are unlikely to give rise to the observed bursts.",9907070v1
2003-09-16,Observability of neutron events above the Greisen-Zatsepin-Kuzmin cut-off due to violation of Lorentz invariance,"The clustering of ultra high energy cosmic ray events suggests that they have
originated from compact sources. One of the possible physical mechanisms by
which ultra high energy nuclei reach the Earth from far away astrophysical
sources (quasars or BL Lac objects) evading the
  Greisen-Zatsepin-Kuzmin (GZK) cut-off is by violation of Lorentz invariance.
Assuming that there is violation of Lorentz invariance, we calculate the
expected number of neutron events from some of the EGRET sources (including
$\gamma$-ray loud BL Lac objects) which can be correlated in direction with
ultra high energy cosmic ray events observed by AGASA above energy
$4\times10^{19}$eV.
  We present in this paper what AGASA should see in future if violation of
Lorentz invariance is responsible for the propagation of ultra high energy
cosmic rays having energies above the GZK cut-off when there is a correlation
of EGRET sources with the ultra high energy cosmic ray events.",0309421v2
1997-11-05,Chaotic Properties of Dilute Two and Three Dimensional Random Lorentz Gases I: Equilibrium Systems,"We compute the Lyapunov spectrum and the Kolmogorov-Sinai entropy for a
moving particle placed in a dilute, random array of hard disk or hard sphere
scatterers - i.e. the dilute Lorentz gas model. This is carried out in two
ways: First we use simple kinetic theory arguments to compute the Lyapunov
spectrum for both two and three dimensional systems. In order to provide a
method that can easily be generalized to non-uniform systems we then use a
method based upon extensions of the Lorentz-Boltzmann (LB) equation to include
variables that characterize the chaotic behavior of the system. The extended LB
equations depend upon the number of dimensions and on whether one is computing
positive or negative Lyapunov exponents. In the latter case the extended LB
equation is closely related to an ""anti-Lorentz-Boltzmann equation"" where the
collision operator has the opposite sign from the ordinary LB equation. Finally
we compare our results with computer simulations of Dellago and Posch and find
very good agreement.",9711008v1
1999-12-10,The Nose-hoover thermostated Lorentz gas,"We apply the Nose-Hoover thermostat and three variations of it, which control
different combinations of velocity moments, to the periodic Lorentz gas.
Switching on an external electric field leads to nonequilibrium steady states
for the four models with a constant average kinetic energy of the moving
particle. We study the probability density, the conductivity and the attractor
in nonequilibrium and compare the results to the Gaussian thermostated Lorentz
gas and to the Lorentz gas as thermostated by deterministic scattering.",9912018v1
2001-02-09,Thermodynamics and Preferred Frame,"The Lorentz covariant statistical physics and thermodynamics is formulated
within the preferred frame approach. The transformation laws for geometrical
and mechanical quantities such as volume and pressure as well as the
Lorentz-invariant measure on the phase space are found using Lorentz
transformation in absolute synchronization. Next, the probability density and
partition function are investigated using the preferred frame approach and the
transformation laws for internal energy, entropy, temperature as well as other
thermodynamical potentials are established. The Lorentz covariance of basic
thermodynamical relations, including Clapeyron's equation and Maxwell's
relations is shown. Finally, the relation of presented approach to the previous
approaches to relativistic thermodynamics is briefly discussed.",0102170v2
2005-03-11,Time dependent simulations of electron transport through a quantum ring: effect of the Lorentz force,"The time dependent Schr\""odinger equation for an electron passing through a
semiconductor quantum ring of nonzero width is solved in the presence of a
perpendicular homogenous magnetic field. We study the effects of the Lorentz
force on the Aharonov-Bohm oscillations. Within the range of incident momentum
for which the ring is transparent at zero magnetic field, the Lorentz force
leads to a decrease of the oscillation amplitude, due to the asymmetry in the
electron injection in the two arms of the ring. For structures in which the
fast electrons are predominantly backscattered, the Lorentz force assists in
the transport producing an initial increase of the corresponding oscillation
amplitude. Furthermore, we discuss the effect of elastic scattering on a
potential cavity within one of the arms of the ring. For the cavity tuned to
shift maximally the phase of the maximum of the wave packet we observe a $\pi$
shift of the Aharonov-Bohm oscillations. For other cavity depths the
oscillations with a period of half of the flux quantum are observed.",0503268v2
1994-09-19,A remark on kinks and time machines,"We describe an elementary proof that a manifold with the topology of the
Politzer time machine does not admit a nonsingular, asymptotically flat Lorentz
metric.",9409040v1
1995-09-25,Some applications of differential topology in general relativity,"Recently, there have been several applications of differential and algebraic
topology to problems concerned with the global structure of spacetimes. In this
paper, we derive obstructions to the existence of spin-Lorentz and pin-Lorentz
cobordisms and we show that for compact spacetimes with non-empty boundary
there is no relationship between the homotopy type of the Lorentz metric and
the causal structure. We also point out that spin-Lorentz and tetrad cobordism
are equivalent. Furthermore, because the original work [7] on metric homotopy
and causality may not be known to a wide audience, we present an overview of
the results here.",9509048v1
1999-04-30,Finslerian spaces possessing local relativistic symmetry,"It is shown that the problem of a possible violation of the Lorentz
transformations at Lorentz factors $\gamma >5\times 10^{10} ,$ indicated by the
situation which has developed in the physics of ultra-high energy cosmic rays
(the absence of the GZK cutoff), has a nontrivial solution. Its essence
consists in the discovery of the so-called generalized Lorentz transformations
which seem to correctly link the inertial reference frames at any values of
$\gamma .$ Like the usual Lorentz transformations, the generalized ones are
linear, possess group properties and lead to the Einstein law of addition of
3-velocities. However, their geometric meaning turns out to be different: they
serve as relativistic symmetry transformations of a flat anisotropic Finslerian
event space rather than of Minkowski space. Consideration is given to two types
of Finsler spaces which generalize locally isotropic Riemannian space-time of
relativity theory, e. g. Finsler spaces with a partially and entirely broken
local 3D isotropy. The investigation advances arguments for the corresponding
generalization of the theory of fundamental interactions and for a specific
search for physical effects due to local anisotropy of space-time.",9904081v1
2000-01-28,On the spontaneous breaking of Lorentz invariance,"We show that estimates of the Lorentz symmetry violation extracted from
ultra-high energy cosmic rays beyond the GZK cut-off set bounds on the
parameters of a Lorentz-violating extension of the Standard Model. Moreover, we
argue that correlated measurements of the difference in the arrival time of
gamma-ray photons and neutrinos emitted from Active Galactic Nuclei or
Gamma-Ray Bursts may provide a signature for a possible violation of the
Lorentz symmetry. We find that this time delay is energy independent, but that
it has a dependence on the chirality of the particles involved.",0001097v1
2002-03-15,Relativistic quantum measurement,"Does the measurement of a quantum system necessarily break Lorentz
invariance? We present a simple model of a detector that measures the spacetime
localization of a relativistic particle in a Lorentz invariant manner. The
detector does not select a preferred Lorentz frame as a Newton-Wigner
measurement would do. The result indicates that there exists a Lorentz
invariant notion of quantum measurement and sheds light on the issue of the
localization of a relativistic particle. The framework considered is that of
single-particle mechanics as opposed to field theory. The result may be taken
as support for the interpretation postulate of the spacetime-states formulation
of single-particle quantum theory.",0203056v2
2003-01-21,Gravitation as Anholonomy,"A gravitational field can be seen as the anholonomy of the tetrad fields.
This is more explicit in the teleparallel approach, in which the gravitational
field-strength is the torsion of the ensuing Weitzenboeck connection. In a
tetrad frame, that torsion is just the anholonomy of that frame. The infinitely
many tetrad fields taking the Lorentz metric into a given Riemannian metric
differ by point-dependent Lorentz transformations. Inertial frames constitute a
smaller infinity of them, differing by fixed-point Lorentz transformations.
Holonomic tetrads take the Lorentz metric into itself, and correspond to
Minkowski flat spacetime. An accelerated frame is necessarily anholonomic and
sees the electromagnetic field strength with an additional term.",0301077v1
2003-03-23,On the Lorentz Invariant Gravitation Field Theory,"The theory of gravitation field within the special theory of relativity is
analyzed.",0303088v1
2003-11-17,"Quantum Gravity Phenomenology, Lorentz Invariance and Discreteness","Contrary to what is often stated, a fundamental spacetime discreteness need
not contradict Lorentz invariance. A causal set's discreteness is in fact
locally Lorentz invariant, and we recall the reasons why. For illustration, we
introduce a phenomenological model of massive particles propagating in a
Minkowski spacetime which arises from an underlying causal set. The particles
undergo a Lorentz invariant diffusion in phase space, and we speculate on
whether this could have any bearing on the origin of high energy cosmic rays.",0311055v3
2003-12-08,Space-Time Foam may Violate the Principle of Equivalence,"The interactions of different particle species with the foamy space-time
fluctuations expected in quantum gravity theories may not be universal, in
which case different types of energetic particles may violate Lorentz
invariance by varying amounts, violating the equivalence principle. We
illustrate this possibility in two different models of space-time foam based on
D-particle fluctuations in either flat Minkowski space or a stack of
intersecting D-branes. Both models suggest that Lorentz invariance could be
violated for energetic particles that do not carry conserved charges, such as
photons, whereas charged particles such electrons would propagate in a
Lorentz-inavariant way. The D-brane model further suggests that gluon
propagation might violate Lorentz invariance, but not neutrinos. We argue that
these conclusions hold at both the tree (lowest-genus) and loop (higher-genus)
levels, and discuss their implications for the phenomenology of quantum
gravity.",0312044v2
2004-04-27,On alternative approaches to Lorentz violation in loop quantum gravity inspired models,"Recent claims point out that possible violations of Lorentz symmetry
appearing in some semiclassical models of extended matter dynamics motivated by
loop quantum gravity can be removed by a different choice of canonically
conjugated variables. In this note we show that such alternative is
inconsistent with the choice of variables in the underlying quantum theory
together with the semiclassical approximation, as long as the correspondence
principle is maintained. A consistent choice will violate standard Lorentz
invariance. Thus, to preserve a relativity principle in this framework, the
linear realization of Lorentz symmetry should be extended or superseded.",0404113v2
2004-11-21,Non-Riemannian acoustic black holes: Hawking radiation and Lorentz symmetry breaking,"A non-Riemannian geometrical approach to the investigation of an acoustic
black hole in irrotational mean flows, based on the Lighthill vortex sound
theory is given. This additional example of analog gravity based on classical
fluids is used to investigate the acoustic Lorentz violation. An example is
given where the contortion vector is distributed along a ring inside the fluid
which can be gravitational analog of the torsion thick string spacetime defect.
It is found that the linear background flow velocity approximation, acoustic
Lorentz symmetry is breaking by the acoustic Cartan contortion in analogy to
the spontaneous gravitational Lorentz breaking in Riemann-Cartan spacetime
discovered recently by Kostelecky. We also show that although the acoustic
torsion contributes to the fiducial observer acceleration, it is not present in
Hawking radiation since is not presnt in the surface gravity of the acoustic
black hole.",0411103v2
2005-10-05,"A ""Lorentz-Poincare""-Type Interpretation of Relativistic Gravitation","The nature of 'time', 'space' and 'reality' are to large extent dependent on
our interpretation of Special (SRT) and General Relativity Theory (GRT). In SRT
essentially two distinct interpretations exist; the ""geometrical""
interpretation by Einstein based on the Principle of Relativity and the
Invariance of the velocity of light and, the ""physical"" Lorentz-Poincar\'e
interpretation with underpinning by rod contractions, clock slowing and light
synchronization, see e.g. (Bohm 1965, Bell 1987). It can be questioned whether
the ""Lorentz-Poincar\'e""-interpretation of SRT can be continued into GRT. We
have shown that till first Post-Newtonian order this is indeed possible
(Broekaert 2004). This requires the introduction of gravitationally modified
Lorentz transformations, with an intrinsical spatially-variable speed of light
$c(r)$, a scalar scaling field $\Phi$ and induced velocity field $w$. Still the
invariance of the locally observed velocity of light is maintained (Broekaert
2005). The Hamiltonian description of particles and photons recovers the 1-PN
approximation of GRT. At present we show the model does obey the Weak
Equivalence Principle from a fixed perspective, and that the implied
acceleration transformations are equivalent with those of GRT.",0510017v1
2005-12-01,A vacuum-like configuration in General Relativity as a manifestation of a Lorentz-invariant mode of five-dimensional gravity,"A Lorentz-invariant cosmological model is constructed within the framework of
five-dimensional gravity. The five-dimensional theorem which is analogical to
the generalized Birkhoff theorem is proved, that corresponds to the Kaluza's
``cylinder condition''. The five-dimensional vacuum Einstein equations have an
integral of motion corresponding to this symmetry, the integral of motion is
similar to the mass function in general relativity (GR). Space closure with
respect to the extra dimensionality follows from the requirement of the absence
of a conical singularity. Thus, the Kaluza-Klein (KK) model is realized
dynamically as a Lorentz-invariant mode of five-dimensional general relativity.
After the dimensional reduction and conformal mapping the model is reduced to
the GR configuration. It contains a scalar field with a vanishing conformally
invariant energy-momentum tensor on the flat space-time background. This zero
mode can be interpreted as a vacuum configuration in GR. As a result the
vacuum-like configuration in GR can be considered as a manifestation of the
Lorentz-invariant empty five-dimensional space.",0512011v1
2005-12-22,Naturalness in emergent spacetime,"Effective field theories (EFTs) have been widely used as a framework in order
to place constraints on the Planck suppressed Lorentz violations predicted by
various models of quantum gravity. There are however technical problems in the
EFT framework when it comes to ensuring that small Lorentz violations remain
small -- this is the essence of the ""naturalness"" problem. Herein we present an
""emergent"" space-time model, based on the ""analogue gravity'' programme, by
investigating a specific condensed-matter system that is in principle capable
of simulating the salient features of an EFT framework with Lorentz violations.
Specifically, we consider the class of two-component BECs subject to
laser-induced transitions between the components, and we show that this model
is an example for Lorentz invariance violation due to ultraviolet physics.
Furthermore our model explicitly avoids the ""naturalness problem"", and makes
specific suggestions regarding how to construct a physically reasonable quantum
gravity phenomenology.",0512139v2
2006-03-14,The flight of the bumblebee: solutions from a vector-induced spontaneous Lorentz symmetry breaking model,"The vacuum solutions arising from a spontaneous breaking of Lorentz symmetry
due to the acquisition of a vacuum expectation value by a vector field are
derived. These include the purely radial Lorentz symmetry breaking (LSB),
radial/temporal LSB and axial/temporal LSB scenarios. It is found that the
purely radial LSB case gives rise to new black hole solutions. Whenever
possible, Parametrized Post-Newtonian (PPN) parameters are computed and
compared to observational bounds, in order to constrain the Lorentz symmetry
breaking scale.",0603057v3
2006-12-20,Brane Lorentz Symmetry from Lorentz Breaking in the Bulk,"We propose the mechanism of spontaneous symmetry breaking of a bulk vector
field as a way to generate the selection of bulk dimensions invisible to the
standard model confined to the brane. By assigning a non-vanishing vacuum value
to the vector field, a direction is singled out in the bulk vacuum, thus
breaking the bulk Lorentz symmetry. We present the condition for induced
Lorentz symmetry on the brane, as phenomenologically required.",0612129v2
2001-06-29,Test of CPT and Lorentz invariance from muonium spectroscopy,"Following a suggestion of Kostelecky et al. we have evaluated a test of CPT
and Lorentz invariance from the microwave spectroscopy of muonium. Hamiltonian
terms beyond the standard model violating CPT and Lorentz invariance would
contribute frequency shifts $\delta\nu_{12}$ and $\delta\nu_{34}$ to $\nu_{12}$
and $\nu_{34}$, the two transitions involving muon spin flip, which were
precisely measured in ground state muonium in a strong magnetic field of 1.7 T.
The shifts would be indicated by anti-correlated oscillations in $\nu_{12}$ and
$\nu_{34}$ at the earth's sidereal frequency. No time dependence was found in
$\nu_{12}$ or $\nu_{34}$ at the level of 20 Hz, limiting the size of some CPT
and Lorentz violating parameters at the level of $2\times10^{-23}$ GeV,
representing Planck scale sensitivity and an order of magnitude improvement in
sensitivity over previous limits for the muon.",0106103v1
2001-10-19,Testing CPT and Lorentz Invariance with the Anomalous Spin Precession of the Muon,"This article discusses tests of CPT and Lorentz invariance with data from the
muon g-2 experiment at Brookhaven National Laboratory. According to an
extension of the Standard Model by Kostelecky et al., CPT/Lorentz violating
terms in the Lagrangian induce a shift of the anomaly frequency omega_a of
muons in a magnetic field. This shift is predicted to be different for positive
and negative muons and to oscillate with the Earth's sidereal frequency. We
discuss the sensitivity of the g-2 experiment to different parameters of this
Standard Model extension and propose an analysis method to search for sidereal
variations of omega_a.",0110044v1
2000-04-01,Lorentz gauge fixing and lattice QED,"The Gribov ambiguity problem is studied for compact lattice QED within the
Lorentz gauge. In the Coulomb phase, Gribov copies are mainly caused by double
Dirac sheets and zero-momentum modes of the gauge fields. Removing them by
(non-) periodic gauge transformations allows to reach the absolute extremum of
the Lorentz gauge functional. For standard Lorentz gauge fixing the Wilson
fermion correlator turns out to be strongly effected by the zero-momentum
modes. A reliable fermion mass estimate requires the proper treatment of these
modes.",0004001v1
1998-10-09,Testing CPT and Lorentz Symmetry with Protons and Antiprotons in Penning Traps,"A theoretical analysis is performed of Penning-trap experiments comparing
protons and antiprotons to test CPT and Lorentz symmetry through measurements
of anomalous magnetic moments and charge-to-mass ratios. Possible CPT and
Lorentz violations arising at a fundamental level are treated in the context of
a general extension of the standard model of particle physics and its
restriction to quantum electrodynamics. In a suggested experiment measuring
anomaly frequencies a bound on CPT violation of 10^{-23} for a relevant figure
of merit is attainable. Experiments comparing cyclotron frequencies are
sensitive within this theoretical framework to different kinds of Lorentz
violation that preserve CPT. Constraints could be obtained on one figure of
merit at 10^{-24} and on another in a related experiment with H- ions and
antiprotons at the level of 10^{-25}.",9810310v1
1999-05-21,Deformed Lorentz Symmetry and Ultra-High Energy Cosmic Rays,"Lorentz symmetry violation (LSV) is often discussed using models of the
$TH\epsilon \mu $ type which involve, basically, energy independent parameters.
However, if LSV is generated at the Planck scale or at some other fundamental
length scale, it can naturally preserve Lorentz symmetry as a low-energy limit
(deformed Lorentz symmetry, DLS). Deformed relativistic kinematics (DRK) would
be consistent with special relativity in the limit $k$ (wave vector) $\to ~0$
and allow for a deformed version of general relativity and gravitation. We
present an updated discussion of the possible implications of this pattern for
cosmic-ray physics at very high energy. A $\approx ~10^{-6}$ LSV at Planck
scale, leading to a DLS pattern, would potentially be enough to produce very
important observable effects on the properties of cosmic rays at the $\approx
\~10^{20} eV$ scale (absence of GZK cutoff, stability of unstable particles,
lower interaction rates, kinematical failure of the parton model...). We
compare our approach with more recent similar claims made by S. Coleman and S.
Glashow from models of the $TH\epsilon \mu$ type.",9905430v2
1999-12-31,Bounding CPT- and Lorentz-Violating Parameters in a Standard-Model Extension,"A general theoretical framework that incorporates possible CPT and Lorentz
violation in an extension of the standard model and in quantum electrodynamics
has been developed over the last decade. The framework originates in the idea
that CPT and Lorentz symmetry could be broken spontaneously in a more
fundamental theory such as string theory. These symmetry violations are
described in the standard-model extension by small terms in the Lagrangian.
Various experiments can bound these quantities. They include Penning-trap
experiments with electrons and positrons, Penning-trap experiments with protons
and antiprotons, and possible experiments with hydrogen and antihydrogen in
traps or beams. I will review aspects of the theory, outline estimated bounds
attainable in specific experiments, and present known bounds from completed
experiments.",9912553v2
2000-08-14,Extra dimensions present a new flatness problem,"There is no known fundamental reason to demand as a cosmological initial
condition that the bulk possess an SO(3,1) isometry. On the contrary, one
expects bulk curvature terms that violate the SO(3,1) isometry at early epochs,
leading to a violation of Lorentz invariance on our brane. Demanding that the
Lorentz noninvariant terms are small leads to a new ``flatness'' problem, not
solved by the usual formulation of inflation. Furthermore, unlike in four
dimensions, the Lorentz violations induced from the bulk curvature cannot
always be removed as the infrared cutoff is taken arbitrarily large. This means
that the equivalence principle in higher dimensions does not guarantee the
equivalence principle in dimensionally reduced theories. Near-future
experiments are expected to severely constrain these Lorentz-violating
``signatures'' of extra dimensions.",0008126v1
2001-10-05,High energy constraints on Lorentz symmetry violations,"Lorentz violation at high energies might lead to non linear dispersion
relations for the fundamental particles. We analyze observational constraints
on these without assuming any a priori equality between the coefficients
determining the amount of Lorentz violation for different particle species. We
focus on constraints from three high energy processes involving photons and
electrons: photon decay, photo-production of electron-positron pairs, and
vacuum Cerenkov radiation. We find that cubic momentum terms in the dispersion
relations are strongly constrained.",0110094v3
2002-05-20,Signals for Lorentz Violation in Electrodynamics,"An investigation is performed of the Lorentz-violating electrodynamics
extracted from the renormalizable sector of the general Lorentz- and
CPT-violating standard-model extension. Among the unconventional properties of
radiation arising from Lorentz violation is birefringence of the vacuum. Limits
on the dispersion of light produced by galactic and extragalactic objects
provide bounds of 3 x 10^{-16} on certain coefficients for Lorentz violation in
the photon sector. The comparative spectral polarimetry of light from
cosmologically distant sources yields stringent constraints of 2 x 10^{-32}.
All remaining coefficients in the photon sector are measurable in
high-sensitivity tests involving cavity-stabilized oscillators. Experimental
configurations in Earth- and space-based laboratories are considered that
involve optical or microwave cavities and that could be implemented using
existing technology.",0205211v1
2002-12-19,Electromagnetic cavities and Lorentz invariance violation,"Within the model of a Lorentz violating extension of the Maxwell sector of
the standard model, modified light propagation leads to a change of the
resonance frequency of an electromagnetic cavity, allowing cavity tests of
Lorentz violation. However, the frequency is also affected by a
material-dependent length change of the cavity due to a modified Coulomb
potential arising from the same Lorentz violation as well. We derive the
frequency change of the cavity taking both into account. The new effects
derived are negligible for present experiments, but will be more pronounced in
future tests using novel resonator materials.",0212289v2
2003-03-18,The μ\to eγand τ\to μγdecays with the inclusion of Lorentz and CPT violating effects,"We study the Lorentz and CPT violating effects on the branching ratio and the
CP violating asymmetry of the lepton flavor violating interactions \mu\to
e\gamma and \tau\to \mu\gamma, in the model III version of the two Higgs
doublet model. Here we consider that the Lorentz and CPT violating effects
exist in the QED part of the interactions and enter into expressions in the
lepton propagators and in the lepton-photon vertex. We observe that there
exists a non-zero CP asymmetry. However, the Lorentz and CPT violating effects
on the braching ratio and the CP asymmetry are negligibly small.",0303149v2
2003-05-20,Phenomenology of Lorentz-Conserving Noncommutative QED,"Recently a version of Lorentz-conserving noncommutative field theory (NCFT)
has been suggested. The underlying Lie algebra of the theory is the same as
that of Doplicher, Fredenhagen, and Roberts. In Lorentz-conserving NCFT the
matrix parameter {theta}^{mu nu} which characterizes the canonical NCFT's is
promoted to an operator {theta hat}^{mu nu} that transforms as a Lorentz
tensor. In this paper, we calculate phenomenological consequences of the QED
version of this theory by looking at various collider processes. In particular
we calculate modifications to Moller scattering, Bhabha scattering, e^+e^- -->
mu^+ mu^- and e^+e^- --> gamma gamma. We obtain bounds on the noncommutativity
scale from the existing experiments at LEP and make predictions for what may be
seen in future collider experiments.",0305225v1
2003-05-31,Non-renormalization Theorem Originating in a New Fixed Point of the Vector Manifestation,"We study the pion velocity at the critical temperature of chiral symmetry
restoration in QCD. Starting from the premise that the bare effective field
theory is to be defined from the underlying QCD, we incorporate the effects of
Lorentz non-invariance into the bare theory by matching an effective field
theory to QCD at a suitable matching scale, and investigate how the Lorentz
non-invariance existing in the bare theory influences physical quantities.
Using the hidden local symmetry model as the effective field theory, where the
chiral symmetry restoration is realized as the vector manifestation (VM), we
find that the pion velocity at the critical temperature receives neither
quantum nor (thermal) hadronic corrections at the critical temperature even
when we start from the bare theory with Lorentz symmetry breaking. This is
likely the manifestation of a new fixed point in the Lorentz non-invariant
formulation of the VM.",0306005v3
2004-07-20,Improved Test of Lorentz Invariance in Electrodynamics,"We report new results of a test of Lorentz invariance based on the comparison
of a cryogenic sapphire microwave resonator and a hydrogen maser. The
experimental results are shown together with an extensive analysis of
systematic effects. Previously, this experiment has set the most stringent
constraint on Kennedy-Thorndike type violations of Lorentz invariance. In this
work we present new data and interpret our results in the general Lorentz
violating extension of the standard model of particle physics (SME). Within the
photon sector of the SME, our experiment is sensitive to seven SME parameters.
We marginally improve present limits on four of these, and by a factor 7 to 10
on the other three.",0407232v2
2004-07-29,Statistical Mechanics and Lorentz Violation,"The theory of statistical mechanics is studied in the presence of
Lorentz-violating background fields. The analysis is performed using the
Standard-Model Extension (SME) together with a Jaynesian formulation of
statistical inference. Conventional laws of thermodynamics are obtained in the
presence of a perturbed hamiltonian that contains the Lorentz violating terms.
As an example, properties of the nonrelativistic ideal gas are calculated in
detail. To lowest order in Lorentz violation, the scalar thermodynamic
variables are only corrected by a rotationally invariant combination of
parameters that mimics a (frame dependent) effective mass. Spin couplings can
induce a temperature independent polarization in the classical gas that is not
present in the conventional case. Precision measurements in the residual
expectation values of the magnetic moment of Fermi gases in the limit of high
temperature may provide interesting limits on these parameters.",0407354v1
2004-12-26,Testing Lorentz invariance by use of vacuum and matter filled cavity resonators,"We consider tests of Lorentz invariance for the photon and fermion sector
that use vacuum and matter-filled cavities. Assumptions on the wave-function of
the electrons in crystals are eliminated from the underlying theory and
accurate sensitivity coefficients (including some exceptionally large ones) are
calculated for various materials. We derive the Lorentz-violating shift in the
index of refraction n, which leads to additional sensitivity for matter-filled
cavities ; and to birefringence in initially isotropic media. Using published
experimental data, we obtain improved bounds on Lorentz violation for photons
and electrons at levels of 10^-15 and below. We discuss implications for future
experiments and propose a new Michelson-Morley type experiment based on
birefringence in matter.",0412385v1
2005-02-11,Supersymmetry and the Lorentz Fine Tuning Problem,"If physics at the Planck scale requires new conceptions of space-time, then
generic renormalizable field theories predict observable violations of Lorentz
invariance in the low energy sector. The little recognized ``Lorentz Fine
Tuning Problem'' comes from logarithmic loop corrections which are not
suppressed to the enormous extent commonly assumed. Fine-tuning of parameters
at the Planck scale is one possible but unpalatable solution. Here we show that
violation of Lorentz invariance is highly suppressed in a supersymmetric
theory, the Wess-Zumino model. We conjecture that supersymmetry may be further
motivated by yet another fine tuning problem of ordinary quantum field
theories.",0502106v2
2005-06-22,Neutrino Constraints on Spontaneous Lorentz Violation,"We study the effect of spontaneous Lorentz violation on neutrinos. We
consider two kinds of effects: static effects, where the neutrino acquires a
Lorentz-violating dispersion relation, and dynamic effects, which arise from
the interactions of the neutrino with the Goldstone boson of spontaneous
Lorentz violation. Static effects are well detailed in the literature. Here,
special emphasis is given to the novel dynamic effect of Goldstone-Cerenkov
radiation, where neutrinos moving with respect to a preferred rest frame can
spontaneously emit Goldstone bosons. We calculate the observable consequences
of this process and use them to derive experimental bounds from SN1987A and the
CMBR. The bounds derived from dynamic effects are complementary to - and in
many cases much stronger than - those obtained from static effects.",0506216v1
2006-01-27,Very Special Relativity,"By Very Special Relativity (VSR) we mean descriptions of nature whose
space-time symmetries are certain proper subgroups of the Poincar\'e group.
These subgroups contain space-time translations together with at least a
2-parameter subgroup of the Lorentz group isomorphic to that generated by
$K_{x}+J_{y}$ and $K_{y}-J_{x}$. We find that VSR implies special relativity
(SR) in the context of local quantum field theory or of CP conservation. Absent
both of these added hypotheses, VSR provides a simulacrum of SR for which most
of the consequences of Lorentz invariance remain wholly or essentially intact,
and for which many sensitive searches for departures from Lorentz invariance
must fail. Several feasible experiments are discussed for which
Lorentz-violating effects in VSR may be detectable.",0601236v1
2006-07-07,The Casimir Force in a Lorentz Violating Theory,"We study the effects of the minimal extension of the standard model including
Lorentz violation on the Casimir force between two parallel conducting plates
in vacuum. We provide explicit solutions for the electromagnetic field using
scalar field analogy, for both the cases in which the Lorentz violating terms
come from the CPT-even or CPT-odd terms. We also calculate the effects of the
Lorentz violating terms for a fermion field between two parallel conducting
plates and analyze the modifications of the Casimir force due to the
modifications of the Dirac equation. In all cases under consideration, the
standard formulas for the Casimir force are modified by either multiplicative
or additive correction factors, the latter case exhibiting different dependence
on the distance between the plates.",0607087v2
2007-03-15,Construction of Lorentz Invariant Amplitudes from Rest Frame Wave Functions in HQET,"Succeeding in predicting 0^+ and 1^+ states of D and D_s heavy mesons by our
semi-relativistic quark potential model, we examine a method how to construct
Lorentz-invariant scattering amplitudes and/or decay widths and develop a
formulation to calculate Lorentz-boosted ones given the rest frame wave
functions in our model.
  To show how effective this is, we apply the formulation to calculate the
semileptonic weak form factors out of the rest frame wave functions of heavy
mesons and numerically calculate the dynamical 1/m_Q corrections to those for
the process B-bar -> D^{(*)}\ell\nu based on our model for heavy mesons. It is
shown that nonvanishing expressions for \rho_1(\omega)=\rho_2(\omega) and
\rho_3(\omega)=\rho_4(\omega)=0 are obtained in a special Lorentz frame, where
\rho_i(\omega) are the parameters used in the Neubert-Rieckert decomposition of
form factors. Various values of form factors are estimated, which are
compatible with recent experimental data as well as other theoretical
calculations.",0703158v3
1992-05-12,Lorentz invariance of effective strings,"Starting from a Poincar\'e invariant field theory of a real scalar field with
interactions governed by a double-well potential in 2+1 dimensions, the Lorentz
representation induced on the collective coordinates describing low-energy
excitations about an effective string background is derived. In this
representation, Lorentz transformations are given in terms of an infinite
series, in powers of derivatives along the worldsheet. Transformations that act
on the direction transverse to the string worldsheet involve a universal
dimension $-1$ term. As a consequence, Lorentz invariance holds in this theory
of long effective strings due to cancellations in the action between irrelevant
terms and the dimension two term that describes free massless scalar fields in
two dimensions. (in plain tex, no macropackages necessary)",9205026v1
1993-08-13,Supersymmetric Calculation of Mixed KäHLER-Gauge and Mixed KäHLER-Lorentz Anomalies,"We present a manifestly supersymmetric procedure for calculating the
contributions from matter loops to the mixed K\""{a}hler-gauge and to the mixed
K\""{a}hler- Lorentz anomalies in $N=1, D=4$ supergravity-matter systems. We
show how this procedure leads to the well-known result for the mixed
K\""{a}hler-gauge anomaly. For general supergravity-matter systems the mixed
K\""{a}hler-Lorentz anomaly is found to contain a term proportional to ${\cal
R}^2$ with a background field dependent coefficient as well as terms
proportional to $(C_{mnpq})^2$ and to the Gauss-Bonnet topological density. We
briefly comment on the relationship between the mixed K\""{a}hler-Lorentz
anomaly and the moduli dependent threshold corrections to gravitational
couplings in $Z_N$ orbifolds.",9308066v1
1996-05-13,"Expectation Values, Lorentz Invariance, and CPT in the Open Bosonic String","The issue of spontaneous breaking of Lorentz and CPT invariance is studied in
the open bosonic string using a truncation scheme to saturate the string-field
action at successively higher levels. We find strong evidence for the existence
of extrema of the action with nonzero expectation values for certain fields.
The Lorentz- and CPT-preserving solution previously suggested in the literature
is confirmed through level 12 in the action. A family of Lorentz-breaking,
CPT-preserving solutions of the equations of motion is found to persist and
converge through level 18 in the action. Two sequences of solutions
spontaneously breaking both Lorentz invariance and CPT are discussed. The
analysis at this level involves the analytical form of over 20,000 terms in the
static potential.",9605088v1
1996-11-13,On Lorentz Invariant Actions for Chiral P-Forms,"We demonstrate how a Lorentz covariant formulation of the chiral p-form model
in D=2(p+1) containing infinitely many auxiliary fields is related to a Lorentz
covariant formulation with only one auxiliary scalar field entering a chiral
p-form action in a nonpolynomial way. The latter can be regarded as a
consistent Lorentz-covariant truncation of the former. We make the Hamiltonian
analysis of the model based on the nonpolynomial action and show that the Dirac
constraints have a simple form and are all of the first class. In contrast to
the Siegel model the constraints are not the square of second-class
constraints. The canonical Hamiltonian is quadratic and determines energy of a
single chiral p-form. In the case of d=2 chiral scalars the constraint can be
improved by use of `twisting' procedure (without the loss of the property to be
of the first class) in such a way that the central charge of the quantum
constraint algebra is zero. This points to possible absence of anomaly in an
appropriate quantum version of the model.",9611100v1
2000-03-24,Spontaneous Breakdown of Lorentz Invariance in IIB Matrix Model,"We study the IIB matrix model, which is conjectured to be a nonperturbative
definition of superstring theory, by introducing an integer deformation
parameter `nu' which couples to the imaginary part of the effective action
induced by fermions. The deformed IIB matrix model continues to be well-defined
for arbitrary `nu', and it preserves gauge invariance, Lorentz invariance, and
the cluster property. We study the model at `nu' = infinity using a
saddle-point analysis, and show that ten-dimensional Lorentz invariance is
spontaneously broken at least down to an eight-dimensional one. We argue that
it is likely that the remaining eight-dimensional Lorentz invariance is further
broken, which can be checked by integrating over the saddle-point
configurations using standard Monte Carlo simulation.",0003223v2
2000-08-02,Supersymmetric Yang-Mills Theory in Eleven Dimensions,"We present a Lorentz invariant lagrangian formulation for a supersymmetric
Yang-Mills vector multiplet in eleven dimensions (11D). The Lorentz symmetry is
broken at the field equation level, and therefore the breaking is spontaneous,
as in other formulations of supersymmetric theories in 12D or higher
dimensions. We introduce a space-like unit vector formed by the gradient of a
scalar field, avoiding the problem of Lorentz non-invariance at the lagrangian
level, which is also an analog of non-commutative geometry with constant field
strengths breaking Lorentz covariance. The constancy of the space-like unit
vector field is implied by the field equation of a multiplier field. The field
equations for the physical fields are formally the same as those of 10D
supersymmetric Yang-Mills multiplet, but now with some constraints on these
fields for supersymmetric consistency. This formulation also utilizes the
multiplier fields accompanied by the bilinear forms of constraints, such that
these multiplier fields will not interfere with the physical field equations.
Based on this component result, we also present a $\k$-symmetric supermembrane
action with the supersymmetric Yang-Mills backgrounds.",0008029v1
2000-12-26,The Galilean Nature of V-duality for Noncommutative Open String and Yang-Mills Theories,"A V-duality conjecture for noncommutative open string theories (NCOS) that
result from decoupling D-branes in Lorentz-boost related backgrounds was put
forward recently in hep-th/0006013. The aim of this paper is to test the
Galilean nature of this conjecture in the gravity dual setup. We start with an
(F, D3) bound state Lorentz-boosted along one D3-brane direction perpendicular
to the F-string, and show that insisting a decoupled NCOS allows only
infinitesimal Lorentz boosts. In this way, it is shown that the V-duality
relates a family of NCOS by Galileo boosts. Starting with a Lorentz-boosted
(D1,D3) bound state, we show that a similar V-duality works for noncommutative
Yang-Mills (NCYM) theories as well. In addition, we deduce by a holography
argument that the running string tension, as a function of the energy scale,
for NCOS (or NCYM) remains unchanged under V-duality.",0012239v2
2002-06-04,Noncommutative Gauge Theory without Lorentz Violation,"The most popular noncommutative field theories are characterized by a matrix
parameter theta^(mu,nu) that violates Lorentz invariance. We consider the
simplest algebra in which the theta-parameter is promoted to an operator and
Lorentz invariance is preserved. This algebra arises through the contraction of
a larger one for which explicit representations are already known. We formulate
a star product and construct the gauge-invariant Lagrangian for
Lorentz-conserving noncommutative QED. Three-photon vertices are absent in the
theory, while a four-photon coupling exists and leads to a distinctive
phenomenology.",0206035v3
2002-08-08,Deformed Lorentz Symmetry and High-Energy Astrophysics (II),"Lorentz symmetry violation (LSV) can be generated at the Planck scale, or at
some other fundamental length scale, and naturally preserve Lorentz symmetry as
a low-energy limit (deformed Lorentz symmetry, DLS). DLS can have important
implications for ultra-high energy cosmic-ray physics (see papers
physics/0003080, astro-ph/0011181 and astro-ph/0011182, and references quoted
in these papers). A crucial question is how DLS can be extended to a deformed
Poincare symmetry (DPS), and what can be the dynamical origin of this
phenomenon. We discuss recent proposals to identify DPS with a symmetry
incorporating the Planck scale (doubly special relativity, DSR) and suggest new
ways in this direction. Implications for models of quadratically deformed
relativistic kinematics (QDRK) and linearly deformed relativistic kinematics
(LDRK) are also discussed.",0208064v1
2002-12-13,Improved Epstein-Glaser Renormalization II. Lorentz invariant framework,"The Epstein--Glaser type T-subtraction introduced by one of the authors in a
previous paper is extended to the Lorentz invariant framework. The advantage of
using our subtraction instead of Epstein and Glaser's standard W-subtraction
method is especially important when working in Minkowski space, as then the
counterterms necessary to keep Lorentz invariance are simplified. We show how
T-renormalization of primitive diagrams in the Lorentz invariant framework
directly relates to causal Riesz distributions. A covariant subtraction rule in
momentum space is found, sharply improving upon the BPHZL method for massless
theories.",0212156v3
2003-09-05,Lorentz invariant nonabelian gauge theory on noncommutative space-time and BRST symmetry,"Lorentz covariance is the fundamental principle of every relativistic field
theory which insures consistent physical descriptions. Even if the space-time
is noncommutative, field theories on it should keep Lorentz covariance. In this
paper, the nonabelian gauge theory on noncommutative spacetime is defined and
its Lorentz invariance is maintained based on the idea of Carlson, Carone and
Zobin. The deviation from the standard model in particle physics has not yet
observed, and so any model beyond standard model must reduce to it in some
approximation. Noncommutative gauge theory must also reproduce standard model
in the limit of noncommutative parameter $\theta^{\mu\nu}\to0$. Referring to
Jur$\check{\text{c}}$o {\it et. al.}, we will construct the nonabelian gauge
theory that deserves to formulate standard model. BRST symmetry is very
important to quantize nonabelian gauge theory and construct the covariant
canonical formulation. It is discussed about the fields in noncommutative gauge
theory without considering those components. Scale symmetry of ghost fields is
also discussed.",0309060v3
2003-11-01,Snyderspace,"We generalize the construction of Snyder to a Lorentz covariant
noncommutative superspace.",0311002v1
2003-11-14,Spontaneous Breaking of Lorentz Invariance,"We describe how a stable effective theory in which particles of the same
fermion number attract may spontaneously break Lorentz invariance by giving
non-zero fermion number density to the vacuum (and therefore dynamically
generating a chemical potential term). This mecanism yields a finite vacuum
expectation value $<\bar\psi\gamma^\mu\psi>$ which we consider in the context
of proposed models that require such a breaking of Lorentz invariance in order
to yield composite degrees of freedom that act approximately like gauge bosons.
We also make general remarks about how the background source provided by
$<\bar\psi\gamma^\mu\psi>$ could relate to work on signals of Lorentz violation
in electrodynamics.",0311127v5
2003-12-30,"Gravity, Lorentz Violation, and the Standard Model","The role of the gravitational sector in the Lorentz- and CPT-violating
Standard-Model Extension (SME) is studied. A framework is developed for
addressing this topic in the context of Riemann-Cartan spacetimes, which
include as limiting cases the usual Riemann and Minkowski geometries. The
methodology is first illustrated in the context of the QED extension in a
Riemann-Cartan background. The full SME in this background is then considered,
and the leading-order terms in the SME action involving operators of mass
dimension three and four are constructed. The incorporation of arbitrary
Lorentz and CPT violation into general relativity and other theories of gravity
based on Riemann-Cartan geometries is discussed. The dominant terms in the
effective low-energy action for the gravitational sector are provided, thereby
completing the formulation of the leading-order terms in the SME with gravity.
Explicit Lorentz symmetry breaking is found to be incompatible with generic
Riemann-Cartan geometries, but spontaneous Lorentz breaking evades this
difficulty.",0312310v2
2004-09-20,Composite Mediators and Lorentz Violation,"We briefly review the history and current status of models of particle
interactions in which massless mediators are given, not by fundamental gauge
fields as in the Standard Model, but by composite degrees of freedom of
fermionic systems. Such models generally require the breaking of Lorentz
invariance. We describe schemes in which the photon and the graviton emerge as
Goldstone bosons from the breaking of Lorentz invariance, as well as
generalizations of the quantum Hall effect in which composite excitations yield
massless particles of all integer spins. While these schemes are of limited
interest for the photon (spin 1), in the case of the graviton (spin 2) they
offer a possible solution to the long-standing UV problem in quantum linear
gravity.",0409189v2
2004-11-27,Lorentz Symmetry Breaking and Planar Effects from Non-Linear Electrodynamics,"We propose a modification of standard linear electrodynamics in four
dimensions, where effective non-trivial interactions of the electromagnetic
field with itself and with matter fields induce Lorentz violating Chern-Simons
terms. This yields two consequences: it provides a more realistic and general
scenario for the breakdown of Lorentz symmetry in electromagnetism and it may
explain the effective behavior of the electromagnetic field in certain planar
phenomena (for instance, Hall effect). A number of proposals for non-linear
electrodynamics is discussed along the paper. Important physical implications
of the breaking of Lorentz symmetry, such as optical birefringence and the
possibility of having conductance in the vacuum are commented on.",0411254v2
2004-12-10,Velocity in Lorentz-Violating Fermion Theories,"We consider the role of the velocity in Lorentz-violating fermionic quantum
theory, especially emphasizing the nonrelativistic regime. Information about
the velocity will be important for the kinematical analysis of scattering and
other problems. Working within the minimal standard model extension, we derive
new expressions for the velocity. We find that generic momentum and spin
eigenstates may not have well-defined velocities. We also demonstrate how
several different techniques may be used to shed light on different aspects of
the problem. A relativistic operator analysis allows us to study the behavior
of the Lorentz-violating Zitterbewegung. Alternatively, by studying the time
evolution of Gaussian wave packets, we find that there are Lorentz-violating
modifications to the wave packet spreading and the spin structure of the wave
function.",0412112v2
2005-01-20,Infrared Lorentz Violation and Slowly Instantaneous Electricity,"We study a modification of electromagnetism which violates Lorentz invariance
at large distances. In this theory, electromagnetic waves are massive, but the
static force between charged particles is Coulomb not Yukawa. At very short
distances the theory looks just like QED. But for distances larger than 1/m the
massive dispersion relation of the waves can be appreciated, and the Coulomb
force can be used to communicate faster than the speed of light. In fact,
electrical signals are transmitted instantly, but take a time ~ 1/m to build up
to full strength. After that, undamped oscillations of the electric field are
set in and continue until they are dispersed by the arrival of the
Lorentz-obeying part of the transmission. We study experimental constraints on
such a theory and find that the Compton wavelength of the photon may be as
small as 6000 km. This bound is weaker than for a Lorentz-invariant mass,
essentially because in our case the Coulomb constraint is removed.",0501157v1
2005-01-28,Spontaneous Lorentz Violation and the Long-Range Gravitational Preferred-Frame Effect,"Lorentz-violating operators involving Standard Model fields are tightly
constrained by experimental data. However, bounds are more model-independent
for Lorentz violation appearing in purely gravitational couplings. The
spontaneous breaking of Lorentz invariance by the vacuum expectation value of a
vector field selects a universal rest frame. This affects the propagation of
the graviton, leading to a modification of Newton's law of gravity. We compute
the size of the long-range preferred-frame effect in terms of the coefficients
of the two-derivative operators in the low-energy effective theory that
involves only the graviton and the Goldstone bosons.",0501223v4
2005-06-15,Lorentz invariant supersymmetric mechanism for non(anti)commutative deformations of space-time geometry,"A supersymmetric Lorentz invariant mechanism for superspace deformations is
proposed. It is based on an extension of superspace by one $\lambda_{a}$ or
several Majorana spinors associated with the Penrose twistor picture. Some
examples of Lorentz invariant supersymmetric Poisson and Mojal brackets are
constructed and the correspondence: $\theta_{mn}\leftrightarrow
i\psi_{m}\psi_{n},\quad C_{ab}\leftrightarrow \lambda_{a}\lambda_{b},\quad
\Psi^{a}_{m}\leftrightarrow \psi_{m}\lambda^{a}$ mapping the brackets depending
on the constant background into the Lorentz covariant supersymmetric brackets
is established. The correspondence reveals the role of the composite
anticommuting vector $\psi_{m}=-{1\over 2}(\bar\theta\gamma_{m}\lambda)$ as a
covariant measure of space-time coordinate noncommutativity.",0506127v3
2005-10-05,Vacuum Polarization Effects in the Lorentz and PCT Violating Electrodynamics,"In this work we report new results concerning the question of dynamical mass
generation in the Lorentz and PCT violating quantum electrodynamics. A one loop
calculation for the vacuum polarization tensor is presented. The electron
propagator, ""dressed"" by a Lorentz breaking extra term in the fermion
Lagrangian density, is approximated by its first order: this scheme is shown to
break gauge invariance. Then we rather consider a full calculation to second
order in the Lorentz breaking parameter: we recover gauge invariance and use
the Schwinger-Dyson equation to discuss the full photon propagator. This allows
a discussion on a possible photon mass shift as well as measurable, observable
physical consequences, such as the Lamb-shift.",0510045v1
2006-03-11,A Comment on the Topological Phase for Anti-Particles in a Lorentz-violating environment,"Recently, a scheme to analyse topological phases in Quantum Mechanics by
means of the non-relativistic limit of fermions non-minimally coupled to a
Lorentz-breaking background has been proposed. In this letter, we show that the
fixed background, responsible for the Lorentz-symmetry violation, may induce
opposite Aharonov-Casher phases for a particle and its corresponding
antiparticle. We then argue that such a difference may be used to investigate
the asymmetry for particle/anti-particle as well as to propose bounds on the
associated Lorentz-symmetry violating parameters.",0603091v2
2006-03-21,"Spontaneous breaking of Lorentz invariance, black holes and perpetuum mobile of the 2nd kind","We study the effect of spontaneous breaking of Lorentz invariance on black
hole thermodynamics. We consider a scenario where Lorentz symmetry breaking
manifests itself by the difference of maximal velocities attainable by
particles of different species in a preferred reference frame. The Lorentz
breaking sector is represented by the ghost condensate. We find that the
notions of black hole entropy and temperature loose their universal meaning. In
particular, the standard derivation of the Hawking radiation yields that a
black hole does emit thermal radiation in any given particle species, but with
temperature depending on the maximal attainable velocity of this species. We
demonstrate that this property implies violation of the second law of
thermodynamics, and hence, allows construction of a perpetuum mobile of the 2nd
kind. We discuss possible interpretation of these results.",0603158v2
2006-04-23,On the consistency of Lorentz invariance violation in QED induced by fermions in constant axial-vector background,"We show for the first time that the induced parity--even Lorentz invariance
violation can be unambiguously calculated in the physically justified and
minimally broken dimensional regularization scheme, suitably tailored for a
spontaneous Lorentz symmetry breaking in a field theory model. The quantization
of the Lorentz invariance violating quantum electrodynamics is critically
examined and shown to be consistent either for a light--like cosmic anisotropy
axial--vector or for a time--like one, when in the presence of a bare photon
mass.",0604164v5
2006-07-17,On the renormalization of CPT/Lorentz violating QED in curved space,"We consider the one-loop renormalization of QED in curved space-time with
additional Lorentz and/or CPT breaking terms. The renormalization group
equations in the vacuum sector are derived. In the special case of Minkowski
metric and with constant Lorentz and CPT breaking terms these equations reduce
to the ones obtained earlier by other authors. The necessary form of the vacuum
counterterms indicate possible violations of the space or time homogeneity or
space isotropy in the gravitational phenomena. However, the necessity of the
phenomenologically most interesting terms such as linear in the space-time
curvature or torsion, is related to the non-constant nature of the
dimensionless Lorentz and CPT breaking parameters.",0607109v2
2006-07-26,Quantum Corrections to Lorentz Invariance Violating Theories: Fine-Tuning Problem,"It is of general agreement that a quantum gravity theory will most probably
mean a breakdown of the standard structure of space-time at the Planck scale.
This has motivated the study of Planck-scale Lorentz Invariance Violating (LIV)
theories and the search for its observational signals. Yet, it has been
recently shown that, in a simple scalar-spinor Yukawa theory, radiative
corrections to tree-level Planck-scale LIV theories can induce large Lorentz
violations at low energies, in strong contradiction with experiment, unless an
unnatural fine-tuning mechanism is present. In this letter, we show the
calculation of the electron self-energy in the framework given by the
Myers-Pospelov model for a Lorentz Invariance Violating QED. We find a
contribution that depends on the prefered's frame four-velocity which is not
Planck-scale suppressed, showing that this model suffers from the same disease.
Comparison with Hughes-Drever experiments requires a fine-tuning of 21 orders
of magnitude for this model not to disagree with experiment.",0607214v2
2006-10-26,Massless and Massive Vector Goldstone Bosons in Nonlinear Quantum Electrodynamics,"The spontaneous Lorentz invariance violation (SLIV) developing in QED type
theories with the nonlinear four-vector field constraint $A_{\mu}^{2}=M^{2}$
(where $M$ is a proposed scale of the Lorentz violation) is considered in the
case when the internal U(1) charge symmetry is also spontaneously broken. We
show that such a SLIV pattern induces the genuine vector Goldstone boson which
appears massless when the U(1) symmetry is exact and becomes massive in its
broken phase. However, for both of phases an apparent Lorentz violation is
completely canceled out in all the observable processes so that the physical
Lorentz invariance in theory is ultimately restored.",0610277v1
2007-01-10,Obtaining the equation of motion for a fermionic particle in a generalized Lorentz-violating system framework,"Using a generalized procedure for obtaining the dispersion relation and the
equation of motion for a propagating fermionic particle, we examine previous
claims for a preferred axis at $n_{\mu}$($\equiv(1,0,0,1)$), $n^{2}=0$ embedded
in the framework of very special relativity (VSR). We show that, in a
relatively high energy scale, the corresponding equation of motion is reduced
to a conserving lepton number chiral equation previously predicted in the
literature. Otherwise, in a relatively low energy scale, the equation is
reduced to the usual Dirac equation for a free propagating fermionic particle.
It is accomplished by the suggestive analysis of some special cases where a
nonlinear modification of the action of the Lorentz group is generated by the
addition of a modified conformal transformation which, meanwhile, preserves the
structure of the ordinary Lorentz algebra in a very peculiar way. Some feasible
experiments, for which Lorentz violating effects here pointed out may be
detectable, are suggested.",0701092v2
1998-09-11,Lorentzian worldlines and Schwarzian derivative,"We relate in this note the classical Schwarzian derivative to the curvature
of time-like curves in Lorentz surfaces of constant curvature.",9809062v1
2004-10-15,Typicality of recurrence for Lorentz gases,"It is a safe conjecture that most (not necessarily periodic) two-dimensional
Lorentz gases with finite horizon are recurrent. Here we formalize this
conjecture by means of a stochastic ensemble of Lorentz gases, in which i.i.d.
random scatterers are placed in each cell of a co-compact lattice in the plane.
  We prove that the typical Lorentz gas, in the sense of Baire, is recurrent,
and give results in the direction of showing that recurrence is an almost sure
property (including a zero-one law that holds in every dimension). A few toy
models illustrate the extent of these results.",0410355v2
2004-11-27,A Remark on the Inequalities of Bernstein - Markov Type in Exponential Orlicz and Lorentz Spaces,"We prove in this article the generalizations on the exponential Orlicz spaces
Markov's - Bernstein's inequalities for algebraic polynomials and rational
functions.",0411617v1
1999-10-20,"Geometric Modular Action, Wedge Duality and Lorentz Covariance are Equivalent for Generalized Free Fields","The Tomita-Takesaki modular groups and conjugations for the observable
algebras of space-like wedges and the vacuum state are computed for
translationally covariant, but possibly not Lorentz covariant, generalized free
quantum fields in arbitrary space-time dimension d. It is shown that for $d\geq
4$ the condition of geometric modular action (CGMA) of Buchholz, Dreyer, Florig
and Summers \cite{BDFS}, Lorentz covariance and wedge duality are all
equivalent in these models. The same holds for d=3 if there is a mass gap. For
massless fields in d=3, and for d=2 and arbitrary mass, CGMA does not imply
Lorentz covariance of the field itself, but only of the maximal local net
generated by the field.",9910032v1
2002-03-28,"Group Theoretical Description of Space Inversion, Time Reversal and Charge Conjugation","A group theoretical description of basic discrete symmetries (space inversion
P, time reversal T and charge conjugation C) is given. Discrete subgroups of
orthogonal groups of multidimensional spaces over the fields of real and
complex numbers are considered in terms of fundamental automorphisms of
Clifford algebras. In accordance with a division ring structure, a complete
classification of automorphism groups is established for the Clifford algebras
over the fields of real and complex numbers. Finite-dimensional representations
of the proper orthochronous Lorentz group are studied in terms of spinor
representations of the Clifford algebras. Real, complex, quaternionic and
octonionic representations of the Lorentz group are considered. The
Atiayh-Bott-Shapiro periodicity is defined on the Lorentz group. Quotient
representations of the Lorentz group are introduced. It is shown that quotient
representations are the most suitable for description of massless physical
fields. An algebraic construction of basic physical fields is presented.",0203059v1
2002-11-20,The interplay of the polar decomposition theorem and the Lorentz group,"It is shown that the polar decomposition theorem of operators in (real)
Hilbert spaces gives rise to the known decomposition in boost and spatial
rotation part of any matrix of the orthochronous proper Lorentz group
$SO(1,3)\uparrow$. This result is not trivial because the polar decomposition
theorem is referred to a positive defined scalar product while the
Lorentz-group decomposition theorem deals with the indefinite Lorentz metric. A
generalization to infinite dimensional spaces can be given. It is finally shown
that the polar decomposition of $SL(2,\bC)$ is preserved by the covering
homomorphism of $SL(2,\bC)$ onto $SO(1,3)\spa\uparrow$",0211047v1
2005-05-17,Variant forms of Eliezer's Theorem,"Over 60 years ago, Eliezer proved the surprising result that an electron
moving radially according to the Lorentz-Dirac equation in the Coulomb field of
a proton will not be attracted to a collision with the proton as expected.
Instead, it is repelled from the proton with proper acceleration increasing
asymptotically with proper time. Proponents of the Lorentz-Dirac equation
sometimes try to explain this away by speculation that the electron must
approach so closely to the proton that the field strength would be beyond the
domain of validity of the classical Lorentz-Dirac equation and therefore
require a quantum-mechanical analysis.
  This note proves some variants of Eliezer's result which apply to *bounded*,
compactly supported, spherically symmetric fields, and thus call into question
such speculation. However, these variants do require the additional hypothesis
(not required by Eliezer) that the electron is unaccelerated before entering
the field--i.e., that ""preacceleration"" is impossible.
  Though these results may not appear in the literature, the methods of proof
are well known. The motivation for writing down careful proofs was continued
skepticism by proponents of the Lorentz-Dirac equation.",0505042v1
2005-08-03,Lorentz surfaces with constant curvature and their physical interpretation,"In recent years it has been recognized that the hyperbolic numbers (an
extension of complex numbers, defined as z=x+h*y with h*h=1 and x,y real
numbers) can be associated to space-time geometry as stated by the Lorentz
transformations of special relativity. In this paper we show that as the
complex numbers had allowed the most complete and conclusive mathematical
formalization of the constant curvature surfaces in the Euclidean space, in the
same way the hyperbolic numbers allow a representation of constant curvature
surfaces with non-definite line elements (Lorentz surfaces). The results are
obtained just as a consequence of the space-time symmetry stated by the Lorentz
group, but, from a physical point of view, they give the right link between
fields and curvature as postulated by general relativity. This mathematical
formalization can open new ways for application in the studies of field
theories.",0508012v1
2005-10-04,The modified Vlasov equations,"The Vlasov system of equations for a plasma is given in relativistic form,
and using the correct expression for the ""Lorentz"" force, that is the one
guaranteing real self-consistency.",0510016v1
2005-11-25,Subgroups of the Group of Generalized Lorentz Transformations and Their Geometric Invariants,"It is shown that the group of generalized Lorentz transformations serves as
relativistic symmetry group of a flat Finslerian event space. Being the
generalization of Minkowski space, the Finslerian event space arises from the
spontaneous breaking of initial gauge symmetry and from the formation of
anisotropic fermion-antifermion condensate. The principle of generalized
Lorentz invariance enables exact taking into account the influence of
condensate on the dynamics of fundamental fields. In particular, the
corresponding generalized Dirac equation turns out to be nonlinear. We have
found two noncompact subgroups of the group of generalized Lorentz symmetry and
their geometric invariants. These subgroups play a key role in constructing
exact solutions of such equation.",0511077v1
2005-03-11,New inversion methods for the Lorentz Integral Transform,"The Lorentz Integral Transform approach allows microscopic calculations of
electromagnetic reaction cross sections without explicit knowledge of final
state wave functions. The necessary inversion of the transform has to be
treated with great care, since it constitutes a so-called ill-posed problem. In
this work new inversion techniques for the Lorentz Integral Transform are
introduced. It is shown that they all contain a regularization scheme, which is
necessary to overcome the ill-posed problem. In addition it is illustrated that
the new techniques have a much broader range of application than the present
standard inversion method of the Lorentz Integral Transform.",0503033v1
1999-02-02,The energy conservation law in classical electrodynamics,"In the framework of the classical Maxwell-Lorentz electrodynamics the energy
conservation law is reconsidered.",9902008v1
2000-07-17,Lorentz angle measurements in irradiated silicon detectors between 77 K and 300 K,"Future experiments are using silicon detectors in a high radiation
environment and in high magnetic fields. The radiation tolerance of silicon
improves by cooling it to temperatures below 180 K. At low temperatures the
mobility increases, which leads to larger deflections of the charge carriers by
the Lorentz force. A good knowledge of the Lorentz angle is needed for design
and operation of silicon detectors. We present measurements of the Lorentz
angle between 77 K and 300 K before and after irradiation with a primary beam
of 21 MeV protons.",0007059v2
2000-08-18,Analysis and Synthesis of the SNS Superconducting RF Control System,"The RF system for the SNS superconducting linac consists of a superconducting
cavity, a klystron, and a low-level RF (LLRF) control system. For a proton
linac like SNS, the field in each individual cavity needs to be controlled to
meet the overall system requirements. The purpose of the LLRF control system is
to maintain the RF cavity field to a desired magnitude and phase by controlling
the klystron driver signal. The Lorentz force detuning causes the shift of the
resonant frequency during the normal operation in the order of a few hundreds
hertz. In order to compensate the Lorentz force detuning effects, the cavity is
pre-tuned into the middle of the expected frequency shift caused by the Lorentz
force detuning. Meanwhile, to reduce the overshoot in the transient response, a
feed-forward algorithm, a linear parameter varying gain scheduling (LPV-GS)
controller, is proposed to get away a repetitive noised caused by the pulsed
operation as well as the Lorentz force detuning effects.",0008163v1
2001-02-26,Relativistic integro-differential form of the Lorentz-Dirac equation in 3D without runaways,"It is well known that the third-order Lorentz-Dirac equation admits runaway
solutions wherein the energy of the particle grows without limit, even when
there is no external force. These solutions can be denied simply on physical
grounds, and on the basis of careful analysis of the correspondence between
classical and quantum theory. Nonetheless, one would prefer an equation that
did not admit unphysical behavior at the outset. Such an equation - an
integro-differential version of the Lorentz-Dirac equation - is currently
available either in 1 dimension only, or in 3 dimensions only in the
non-relativistic limit.
  It is shown herein how the Lorentz-Dirac equation may be integrated without
approximation, and is thereby converted to a second-order integro-differential
equation in 3D satisfying the above requirement. I.E., as a result, no
additional constraints on the solutions are required because runaway solutions
are intrinsically absent. The derivation is placed within the historical
context established by standard works on classical electrodynamics by Rohrlich,
and by Jackson.",0102087v3
2001-05-03,"Stresses, energy flow and energy density of gravitational nature","Two arguments which show the validity of the concept of gravitational energy
put forward by Lorentz and Levi-Civita.",0105010v1
2002-04-26,An algorithm for calculating the Lorentz angle in silicon detectors,"Future experiments will use silicon sensors in the harsh radiation
environment of the LHC (Large Hadron Collider) and high magnetic fields. The
drift direction of the charge carriers is affected by the Lorentz force due to
the high magnetic field. Also the resulting radiation damage changes the
properties of the drift.
  In this paper measurements of the Lorentz angle of electrons and holes before
and after irradiation are reviewed and compared with a simple algorithm to
compute the Lorentz angle.",0204078v2
2003-05-09,Signs of Lorentz violation in electrodynamics: variable speed of light and the photon mass,"Recent studies of spacetime anisotropy in the context of local Lorentz
invariance (LLI) based on classical Michelson-Morley experiments, as well
Kennedy-Thorndyke tests, pointed out the existence of terms first order in v/c
and of angular signatures independent of v. This contribution replaces the
Lorentz symmetry by a velocity gauge transformation following an argument
centred on observability. Results show even and odd order terms and indicate
that motion is always underestimated in the spatiotemporal platform. Though LLI
is not recovered in exact special relativistic terms, the alternative looks
compatible with the relational aspects of general relativity (GR) with variable
speed of light models as well a nonzero photon mass. This raises the hypothesis
that Einstein equivalence principle, and consequently LLI, is a cornerstone of
GR, but not necessarily a fundamental one of SR",0305037v2
2003-11-10,The exact proof that Maxwell equations with the 3D E and B are not Lorentz covariant equations. The new Lorentz invariant field equations,"In this paper it will be exactly proved both in the geometric algebra and
tensor formalisms that the usual Maxwell equations with the three-dimensional
(3D) vectors of the electric and magnetic fields, E{bold} and B{bold}
respectively, are not, contrary to the general opinion, Lorentz covariant
equations. Consequently they are not equivalent to the field equations with the
observer independent quantities, the electromagnetic field tensor Fsup{ab}
(tensor formalism) or with the bivector field F (the geometric algebra
formalism). Different 4D algebric objects are used to represent the standard
observer dependent and the new observer independent electric and magnetic
fields. The proof of a fundamental disagreement between the standard
electromagnetism and the special relativity does not depend on the character of
the 4D algebric object used to represent the electric and magnetic fields. The
Lorentz invariant field equations are presented with 1-vectors E and B,
bivectors Esub{HL} and Bsub{HL} and the abstract tensors, the 4-vectors Esup{a}
and Bsup{a}. All these quantities are defined without reference frames. Such
field equations are in a complete agreement with experiments.",0311043v1
2004-08-02,A note: the relativistic transformations for the optical constants of media,"The Lorentz transformations for the optical constants (electric permittivity,
magnetic permeability and index of refraction) of moving media are considered.",0408005v1
2005-08-31,Passive Lorentz transformations with spacetime algebra,"In special relativity, spacetime algebra (STA) provides a powerful and
insightful approach to an invariant formulation of physics. However, in this
geometric algebra of spacetime, relativistic physics is usually considered a
misnomer: STA provides us with an invariant (coordinate-free) formulation and
hence it seems that (passive) Lorentz transformations are misplaced. However,
in order to interpret experimental results, it is important to relate invariant
physical quantities to some reference frame. In this paper, passive Lorentz
transformations are derived using STA but without the second postulate on the
speed of light used by Einstein. This derivation sheds light on the physical
background of STA and, at the same time, clarifies Lorentz transformations in
the proper setting of (Minkowski) four-dimensional spacetime.",0508225v2
2006-06-20,The Lorentz-Einstein length contraction is a real effect,"An elementary thought experiment is used to show that once the time
dilatation effect is established, there is no way to escape a dual length
contraction.",0606171v1
2007-02-19,Lorentz transformations: Einstein's derivation simplified,"We show that the Lorentz transformations for the space-time coordinates of
the same event are a direct consequence of the principle of relativity and of
Einstein's distant clocks synchronization procedure. In our approach, imposing
the linear character of the Lorentz transformations we guess that the
transformation equation for the space coordinate has the form x=ax'+cbt'.
Imposing the condition that it accounts for the time dilation relativistic
effect and taking into account the fact that due to the clock synchronization a
la Einstein the space-time coordinates of the same event in the two frames are
related by x=ct and x'=ct', we find out expressions for a and b. Dividing the
transformation equation for the space coordinate by c we obtain the
transformation equation for the time coordinate t=at'+b/cx'. Combining the two
transformation equations we obtain directly the inverse Lorentz
transformations.",0702157v1
2001-08-09,The Lorentz singular value decomposition and its applications to pure states of 3 qubits,"All mixed states of two qubits can be brought into normal form by the action
of SLOCC operations of the kind $\rho'=(A\otimes B)\rho(A\otimes B)^\dagger$.
These normal forms can be obtained by considering a Lorentz singular value
decomposition on a real parameterization of the density matrix. We show that
the Lorentz singular values are variationally defined and give rise to
entanglement monotones, with as a special case the concurrence. Next a
necessary and sufficient criterion is conjectured for a mixed state to be
convertible into another specific one with a non-zero probability. Finally the
formalism of the Lorentz singular value decomposition is applied to tripartite
pure states of qubits. New proofs are given for the existence of the GHZ- and
W-class of states, and a rigorous proof for the optimal distillation of a
GHZ-state is derived.",0108043v1
2005-11-08,Maps for Lorentz transformations of spin,"Lorentz transformations of spin density matrices for a particle with positive
mass and spin 1/2 are described by maps of the kind used in open quantum
dynamics. They show how the Lorentz transformations of the spin depend on the
momentum. Since the spin and momentum generally are entangled, the maps
generally are not completely positive and act in limited domains. States with
two momentum values are considered, so the maps are for the spin qubit
entangled with the qubit made from the two momentum values, and results from
the open quantum dynamics of two coupled qubits can be applied. Inverse maps
are used to show that every Lorentz transformation completely removes the spin
polarization, and so completely removes the information, from a number of spin
density matrices. The size of the spin polarization that is removed is
calculated for particular cases.",0511067v1
2006-12-08,Concurrence of Lorentz-positive maps,"Let L_n be the n-dimensional Lorentz cone. A linear map M from R^m to R^n is
called Lorentz-positive if M[L_m] is contained in L_n. We extend the notion of
concurrence, which was initially introduced to quantify the entanglement of
bipartite density matrices, to Lorentz-positive maps and provide an explicite
formula for it. This allows us to obtain formulae for the concurrence of
arbitrary positive operators taking 2 x 2 complex hermitian matrices as input
and consequently of arbitrary bipartite density matrices of rank 2. Namely, let
P: H(2) \to H(d) be a positive operator, and let \lambda_1,...,\lambda_4 be the
generalized eigenvalues of the pencil \sigma_2(P(X)) - \lambda det X, in
decreasing order, where \sigma_2 is the second symmetric function of the
spectrum. Then the concurrence is given by the expression C(P;X) =
2\sqrt{\sigma_2(P(X)) - \lambda_2 det X}. As an application, we compute the
concurrences of the density matrices of all graphs with 2 edges. Similar
results apply for a function which we call I-fidelity, with the second largest
generalized eigenvalue \lambda_2 replaced by the smallest eigenvalue \lambda_4.",0612064v1
2007-04-16,Ordered addition of two Lorentz boosts through spatial and space-time rotations,"The ordered addition of two Lorentz boosts is normally shown to result in a
boost by utilizing concepts from group theory and non-Euclidian geometry. We
present a method for achieving this addition by performing a sequence of
spatial rotations and uni-dimensional Lorentz transformations. The method is
first developed for two-dimensional space and it is then extended to
three-dimensional space by utilizing the commutative property of the rotation
of the y-z plane and a boost along the x-axis. The method employs only matrix
multiplication and certain invariant quantities that are natural consequences
of spatial rotations and Lorentz transformations. The combining of two boosts
in different directions into a single boost cannot be expected a priori because
we show that the converse of this statement is not true. That is, two rotations
interspersed with a boost cannot always be reduced to a single rotation
preceded and followed by boosts.",0704.2023v3
2007-05-14,Neutrino telescope modelling of Lorentz invariance violation in oscillations of atmospheric neutrinos,"One possible feature of quantum gravity may be the violation of Lorentz
invariance. In this paper we consider one particular manifestation of the
violation of Lorentz invariance, namely modified dispersion relations for
massive neutrinos. We show how such modified dispersion relations may affect
atmospheric neutrino oscillations. We then consider how neutrino telescopes,
such as ANTARES, may be able to place bounds on the magnitude of this type of
Lorentz invariance violation.",0705.1897v3
2007-09-27,The Integrability of Pauli System in Lorentz Violating Background,"We systematically analyze the integrability of a Pauli system in Lorentz
violating background at the non-relativistic level both in two- and
three-dimensions. We consider the non-relativistic limit of the Dirac equation
from the QED sector of the so-called Standard Model Extension by keeping only
two types of background couplings, the vector a_mu and the axial vector b_mu.
We show that the spin-orbit interaction comes as a higher order correction in
the non-relativistic limit of the Dirac equation. Such an interaction allows
the inclusion of spin degree non-trivially, and if Lorentz violating terms are
allowed, they might be comparable under special circumstances. By including all
possible first-order derivative terms and considering the cases a\ne 0, b\ne 0,
and b_0\ne 0 one at a time, we determine the possible forms of constants of
motion operator, and discuss the existence or continuity of integrability due
to Lorentz violating background.",0709.4276v1
2007-09-29,The Lorentz force effect on the On-Off dynamo intermittency,"An investigation of the dynamo instability close to the threshold produced by
an ABC forced flow is presented. We focus on the on-off intermittency behavior
of the dynamo and the counter-effect of the Lorentz force in the non-linear
stage of the dynamo. The Lorentz force drastically alters the statistics of the
turbulent fluctuations of the flow and reduces their amplitude. As a result
much longer burst (on-phases) are observed than what is expected based on the
amplitude of the fluctuations in the kinematic regime of the dynamo. For large
Reynolds numbers, the duration time of the ``On'' phase follows a power law
distribution, while for smaller Reynolds numbers the Lorentz force completely
kills the noise and the system transits from a chaotic state into a ``laminar''
time periodic flow. The behavior of the On-Off intermittency as the Reynolds
number is increased is also examined. The connections with dynamo experiments
and theoretical modeling are discussed.",0710.0063v1
2007-10-03,Testing for Lorentz Violation: Constraints on Standard-Model Extension Parameters via Lunar Laser Ranging,"We present constraints on violations of Lorentz Invariance based on Lunar
Laser Ranging (LLR) data. LLR measures the Earth-Moon separation by timing the
round-trip travel of light between the two bodies, and is currently accurate to
a few centimeters (parts in $10^{11}$ of the total distance). By analyzing
archival LLR data under the Standard-Model Extension (SME) framework, we
derived six observational constraints on dimensionless SME parameters that
describe potential Lorentz-violation. We found no evidence for Lorentz
violation at the $10^{-6}$ to $10^{-11}$ level in these parameters.",0710.0702v1
2007-10-10,Majorana spinors and extended Lorentz symmetry in four-dimensional theory,"An extended local Lorentz symmetry in four-dimensional (4D) theory is
considered. A source of this symmetry is a group of general linear
transformations of four-component Majorana spinors GL(4,M) which is isomorphic
to GL(4,R) and is the covering of an extended Lorentz group in a 6D Minkowski
space M(3,3) including superluminal and scaling transformations. Physical
space-time is assumed to be a 4D pseudo-Riemannian manifold. To connect the
extended Lorentz symmetry in the M(3,3) space with the physical space-time, a
fiber bundle over the 4D manifold is introduced with M(3,3) as a typical fiber.
The action is constructed which is invariant with respect to both general 4D
coordinate and local GL(4,M) spinor transformations. The components of the
metric on the 6D fiber are expressed in terms of the 4D pseudo-Riemannian
metric and two extra complex fields: 4D vector and scalar ones. These extra
fields describe in the general case massive particles interacting with an extra
U(1) gauge field and weakly interacting with ordinary particles, i.e.
possessing properties of invisible (dark) matter.",0710.1890v1
2007-12-28,Lorentz-symmetry violating decays in a medium,"Various decay processes, such as the decay of a spin-1 particle into two
photons or the gravitational decay of a spin-1/2 fermion, are forbidden in the
vacuum by a combination of requirements, including angular momentum
conservation, Lorentz invariance and gauge invariance. We show that such
processes can occur in a medium, such as a thermal background of particles,
even if it is homogeneous and isotropic. We carry out a model-independent
analysis of the vertex function for such processes in terms of a set of form
factors, and show that the amplitude can be non-zero while remaining consistent
with the symmetry principles mentioned above. The results simulate Lorentz
symmetry violating effects, although in this case they arise from completely
Lorentz-invariant physics.",0712.4345v1
2008-02-12,Have we tested Lorentz invariance enough?,"Motivated by ideas from quantum gravity, Lorentz invariance has undergone
many stringent tests over the past decade and passed every one. Since there is
no conclusive reason from quantum gravity that the symmetry \textit{must} be
violated at some point we should ask the questions: a) are the existing tests
sufficient that the symmetry is already likely exact at the Planck scale? b)
Are further tests simply blind searches for new physics without reasonable
expectation of a positive signal? Here we argue that the existing tests are not
quite sufficient and describe some theoretically interesting areas of existing
parameterizations for Lorentz violation in the infrared that are not yet ruled
out but are accessible (or almost accessible) by current experiments. We
illustrate this point using a vector field model for Lorentz violation
containing operators up to mass dimension six and analyzing how terrestrial
experiments, neutrino observatories, and Auger results on ultra-high energy
cosmic rays limit this model.",0802.1561v1
2008-02-15,Lorentz violating extension of the Standard Model and the Beta-decay end-point,"The Standard Model extension with additional Lorentz violating terms allows
for redefining the equation of motion of a propagating left-handed fermionic
particle. The obtained Dirac-type equation can be embedded in a generalized
Lorentz-invariance preserving-algebra through the definition of Lorentz
algebra-like generators with a light-like preferred axis. The resulting
modification to the fermionic equation of motion introduces some novel
ingredients to the phenomenological analysis of the cross section of the
tritium $\beta$-decay. Assuming lepton number conservation, our formalism
provides a natural explanation for the tritium $\beta$-decay end-point via an
effective neutrino mass term without the need of a sterile right-handed state.",0802.2199v2
2008-02-26,Testing Lorentz and CPT Invariance with MINOS Near Detector Neutrinos,"We present an analysis designed to search for Lorentz and CPT violations as
predicted by the SME framework using the charged current neutrino events in the
MINOS near detector. In particular we develop methods to identify periodic
variations in the normalized number of charged current neutrino events as a
function of sidereal phase. To test these methods, we simulated a set of 1,000
experiments without Lorentz and CPT violation signals using the standard MINOS
Monte Carlo. We performed an FFT on each of the simulated experiments to find
the distribution of powers in the sidereal phase diagram without a signal. We
then injected a signal of increasing strength into the sidereal neutrino
oscillation probability until we found a 5$\sigma$ deviation from the mean in
the FFT power spectrum. By this method, we can establish upper limits for the
Lorentz and CPT violating terms in the SME.",0802.3785v1
2008-06-15,The relation between black hole masses and Lorentz factors of the jet components in blazars,"We explore the relation between black hole mass ($M_{\rm BH}$) and the motion
of the jet components for a sample of blazars. The Very Long Baseline Array
(VLBA) 2cm Survey and its continuation: Monitoring of Jets in active galactic
nuclei (AGNs) with VLBA Experiments (MOJAVE) have observed 278 radio-loud AGNs,
of which 146 blazars have reliable measurements on their apparent velocities of
jet components. We calculate the minimal Lorentz factors for these sources from
their measured apparent velocities, and their black hole masses are estimated
with their broad-line widths. A significant intrinsic correlation is found
between black hole masses and the minimal Lorentz factors of the jet
components, which the Eddington ratio is only weakly correlated with the
minimal Lorentz factor, which may imply that the Blandford-Znajek (BZ)
mechanism may dominate over the Blandford-Payne (BP) mechanism for the jet
acceleration (at least) in blazars.",0806.2435v1
2008-09-17,Astrophysical Tests of Lorentz and CPT Violation with Photons,"A general framework for tests of Lorentz invariance with electromagnetic
waves is presented, allowing for operators of arbitrary mass dimension.
Signatures of Lorentz violations include vacuum birefringence, vacuum
dispersion, and anisotropies. Sensitive searches for violations using sources
such as active galaxies, gamma-ray bursts, and the cosmic microwave background
are discussed. Direction-dependent dispersion constraints are obtained on
operators of dimension 6 and 8 using gamma-ray bursts and the blazar Markarian
501. Stringent constraints on operators of dimension 3 are found using 5-year
data from the Wilkinson Microwave Anisotropy Probe. No evidence appears for
isotropic Lorentz violation, while some support at one sigma is found for
anisotropic violation.",0809.2846v2
2008-10-01,Lorentz-violating contributions of the Carroll-Field-Jackiw model to the CMB anisotropy,"We study the finite temperature properties of the
Maxwell-Carroll-Field-Jackiw (MCFJ) electrodynamics for a purely spacelike
background. Starting from the associated finite temperature partition function,
a modified black body spectral distribution is obtained. We thus show that, if
the CMB radiation is described by this model, the spectrum presents an
anisotropic angular energy density distribution. We show, at leading order,
that the Lorentz-breaking contributions for the Planck's radiation law and for
the Stefan-Boltzmann's law are nonlinear in frequency and quadratic in
temperature, respectively. Using our results, we set up bounds for the
Lorentz-breaking parameter, and show that Lorentz violation in the context of
the MCFJ model is unable to yield the known CMB anisotropy (of 1 part in
$10^{5})$.",0810.0306v2
2008-11-06,Lorentz violation and black-hole thermodynamics,"We consider nonstandard photons from nonbirefringent modified Maxwell theory
and discuss their propagation in a fixed Schwarzschild spacetime background.
This particular modification of Maxwell theory is Lorentz-violating and allows
for maximal photon velocities differing from the causal speed c of the
asymptotic background spacetime. In the limit of geometrical optics, light rays
from modified Maxwell theory are found to propagate along null geodesics in an
effective metric. We observe that not every Lorentz-violating theory with
multiple maximal velocities different from the causal speed c modifies the
notion of the event horizon, contrary to naive expectations. This result
implies that not every Lorentz-violating theory with multiple maximal
velocities necessarily leads to a contradiction with the generalized second law
of thermodynamics.",0811.0943v4
2009-02-03,Lorentz symmetry breaking as a quantum field theory regulator,"Perturbative expansions of relativistic quantum field theories typically
contain ultraviolet divergences requiring regularization and renormalization.
Many different regularization techniques have been developed over the years,
but most regularizations require severe mutilation of the logical foundations
of the theory. In contrast, breaking Lorentz invariance, while it is certainly
a radical step, at least does not damage the logical foundations of the theory.
We shall explore the features of a Lorentz symmetry breaking regulator in a
simple polynomial scalar field theory, and discuss its implications. We shall
quantify just ""how much"" Lorentz symmetry breaking is required to fully
regulate the theory and render it finite. This scalar field theory provides a
simple way of understanding many of the key features of Horava's recent article
[arXiv:0901.3775 [hep-th]] on 3+1 dimensional quantum gravity.",0902.0590v3
2009-04-02,Time-delay and Doppler tests of the Lorentz symmetry of gravity,"Modifications to the classic time-delay effect and Doppler shift in General
Relativity (GR) are studied in the context of the Lorentz-violating
Standard-Model Extension (SME). We derive the leading Lorentz-violating
corrections to the time-delay and Doppler shift signals, for a light ray
passing near a massive body. It is demonstrated that anisotropic coefficients
for Lorentz violation control a time-dependent behavior of these signals that
is qualitatively different from the conventional case in GR. Estimates of
sensitivities to gravity-sector coefficients in the SME are given for current
and future experiments, including the recent Cassini solar conjunction
experiment.",0904.0278v2
2009-06-10,"CPT, Lorentz invariance and anomalous clash of symmetries","In this paper we first discuss the analysis regarding the role of Lorentz
symmetry in the perturbative non-gravitational anomalies for a family of
fermions, which has been recently performed in arXiv:0809.0184. The theory is
assumed to be translational invariant, power-counting renormalizable and based
on a local action, but is allowed to have general Lorentz violating operators,
including those that break CPT. The main result is that Lorentz symmetry does
not participate in the clash of symmetries that leads to the anomalies.
Moreover, here we provide a simple ""semiclassical"" argument that shortly
illustrates the origin of this fact.",0906.2010v1
2009-06-15,Lorentz-violating Chern-Simons action under high temperature in massless QED,"Lorentz and CPT violating QED with massless fermions at finite temperature is
studied. We show that there is no ambiguity in the induced coefficient of the
Chern-Simons-like term that defines the so-called Carroll-Field-Jackiw model at
high temperature. We also show that this system constitutes an example where
the breaking of CPT and Lorentz symmetries is more severe at high temperature
than in the zero temperature case thus precluding any naive expectations of
Lorentz symmetry restoration.",0906.2786v3
2009-06-16,Gauge Theory of the full Lorentz Group on flat Spacetime,"We compute gauge theories of the Lorentz group. We discuss non-interacting,
and interacting fermionic systems. The interacting system combines a local with
a global Lorentz group, i.e, discusses a $SO(3,1)_{l}\times
SO(3,1)_{g}$-theory. We compute the equations of motion and conservation laws
for the fermionic matter current. The core of our work is the prediction of
some new form of monopoles we call 'Dirac-Clifford-'t Hooft-Polyakov'-monopole.
It resides in a state similar to color-flavor locking. Dirac-Clifford-'t
Hooft-Polyakov-monopoles are invariant under global Lorentz transformations and
are predicted to form vortices. The theory is renormalizable, since all
Goldstone-Nambu modes are converted into massive vector gauge fields.",0906.2965v8
2009-06-26,Unsuitability of the moving light clock system for the Lorentz factor derivation,"The moving light clock system was analyzed with respect to the orientation of
the wavefront of the light pulse observed in the moving and stationary frames
of reference. The plane wavefront of the light pulse was oriented horizontally
in both the frames. The wavefront observed in the stationary frame was not
perpendicular to the direction of the light pulse propagation. This showed
different characteristics of the light pulse than that assumed in the Lorentz
factor derivation. According to the horizontal orientation of the wavefront,
velocity c was determined as the vertical component of the light pulse motion
observed in the stationary frame. Application of this velocity distribution in
the Lorentz factor derivation showed the same travel time for the light pulse
observed in the moving and stationary frames of reference. The moving light
clock system was therefore found to be unsuitable for the Lorentz factor
derivation and illustration of time dilation, and shown to illustrate the
relativity of the observation of light rather than the relativity of time.",0906.4897v1
2009-08-10,Perturbative Lorentz and CPT violation for neutrino and antineutrino oscillations,"The effects of perturbative Lorentz and CPT violation on neutrino
oscillations are studied. Features include neutrino-antineutrino oscillations,
direction dependence, and unconventional energy behavior. Leading-order
corrections arising from renormalizable operators are derived in the general
three-flavor effective field theory. The results are applied to neutrino-beam
experiments with long baselines, which offer excellent sensitivity to the
accompanying effects. Key signatures of Lorentz and CPT violation using
neutrino beams include sidereal variations in the oscillation probabilities
arising from the breakdown of rotational symmetry, and CPT asymmetries
comparing neutrino and antineutrino modes. Attainable sensitivities to
coefficients for Lorentz violation are estimated for several existing and
future experiments.",0908.1401v2
2009-09-01,Lorentz violation and black-hole thermodynamics: Compton scattering process,"A Lorentz-noninvariant modification of quantum electrodynamics (QED) is
considered, which has photons described by the nonbirefringent sector of
modified Maxwell theory and electrons described by the standard Dirac theory.
These photons and electrons are taken to propagate and interact in a
Schwarzschild spacetime background. For appropriate Lorentz-violating
parameters, the photons have an effective horizon lying outside the
Schwarzschild horizon. A particular type of Compton scattering event, taking
place between these two horizons (in the photonic ergoregion) and ultimately
decreasing the mass of the black hole, is found to have a nonzero probability.
These events perhaps allow for a violation of the generalized second law of
thermodynamics in the Lorentz-noninvariant theory considered.",0909.0160v4
2009-09-17,Generalized bumblebee models and Lorentz-violating electrodynamics,"The breaking of Lorentz symmetry via a dynamical mechanism, with a tensor
field which takes on a non-zero expectation value in vacuum, has been a subject
of significant research activity in recent years. In certain models of this
type, the perturbations of the ""Lorentz-violating field"" about this background
may be identified with known forces. I present the results of applying this
interpretation to the ""generalized bumblebee models"" found in a prior work. In
this model, the perturbations of a Lorentz-violating vector field can be
interpreted as a photon field. However, the speed of propagation of this
""bumblebee photon"" is direction-dependent and differs from the limiting speed
of conventional matter, leading to measurable physical effects. Bounds on the
parameters of this theory can then be derived from resonator experiments,
accelerator physics, and cosmic ray observations.",0909.3118v2
2009-09-30,"On the importance of Lorentz structure in the parton model: target mass corrections, transverse momentum dependence, positivity bounds","We show that respecting the underlying Lorentz structure in the parton model
has very strong consequences. Failure to insist on the correct Lorentz
covariance is responsible for the existence of contradictory results in the
literature for the polarized structure function g_2(x), whereas with the
correct imposition we are able to derive the Wandzura-Wilczek relation for
g_2(x) and the target-mass corrections for polarized deep inelastic scattering
without recourse to the operator product expansion. We comment briefly on the
problem of threshold behaviour in the presence of target-mass corrections.
Careful attention to the Lorentz structure has also profound implications for
the structure of the transverse momentum dependent parton densities often used
in parton model treatments of hadron production, allowing the k_T dependence to
be derived explicitly. It also leads to stronger positivity and Soffer-type
bounds than usually utilized for the collinear densities.",0909.5650v1
2009-10-07,Renormalization of Lorentz non-invariant actions and manifest T-duality,"We study general two-dimensional sigma-models which do not possess manifest
Lorentz invariance. We show how demanding that Lorentz invariance is recovered
as an emergent on-shell symmetry constrains these sigma-models. The resulting
actions have an underlying group-theoretic structure and resemble Poisson-Lie
T-duality invariant actions. We consider the one-loop renormalization of these
models and show that the quantum Lorentz anomaly is absent. We calculate the
running of the couplings in general and show, with certain non-trivial
examples, that this agrees with that of the T-dual models obtained classically
from the duality invariant action. Hence, in these cases solving constraints
before and after quantization are commuting operations.",0910.1345v2
2009-11-18,On the aether-like Lorentz-breaking actions,"We demonstrate the generation of the CPT-even, aether-like Lorentz-breaking
actions for the scalar and electromagnetic fields via their appropriate
Lorentz-breaking coupling to spinor fields in three, four and five space-time
dimensions. Besides, we show that the aether-like terms for the spinor field
also can be generated as a consequence of the same couplings. Also we discuss
the dispersion relations in the theories with aether-like Lorentz-breaking
terms and find the tree-level effective (Breit) potential for fermion
scattering and the one-loop effective potential corresponding to the action of
the scalar field.",0911.3548v3
2009-11-27,Renormalization group flows in a Lifshitz-like four fermi model,"We study renormalization group flows in the Lifshitz-like $N$-flavour four
fermi model discussed in 0905.2928. In the large-$N$ limit, a nontrivial flow
occurs in only one of all possible marginal couplings and one relevant
coupling, which provides the scale for Lorentz invariance violations. We
discuss in detail the phase diagram and RG flows in the space of couplings,
which includes the Lifshitz fixed point, the free field fixed point and a new
fixed point characterized by $z=1$ scaling and a violation of Lorentz
invariance, which cannot be tuned away by adjusting a parameter. In the broken
symmetry phase, the model flows from the $z=3$ Lifshitz-like fixed point in the
ultraviolet to this new fixed point in the infrared. However, in a modified
version of the present model, which has an effective ultraviolet cut-off much
smaller than the Lorentz invariance violating scale, the infrared behaviour is
governed by an approximately Lorentz invariant theory, similar to the low
energy limit of the usual relativistic Nambu$-$Jona-Lasinio model. Such a
modified model could be realized by a supersymmetric version of the present
model.",0911.5316v1
2010-02-27,A quaternionic unification of electromagnetism and hydrodynamics,"We have derived energy conservation equations from the quaternionic Newton's
law that is compatible with Lorentz transformation. This Newton's law yields
directly the Euler equation and other equations governing the fluid motion.
With this formalism, the pressure contributes positively to the dynamics of the
system in the same way mass does. Hydrodynamic equations are derived from
Maxwell's equations by adopting an electromagnetohydrodynamics (EMH) analogy.
In this analogy the hydroelectric field is related to the local acceleration of
the fluid and the Lorentz gauge is related to the incompressible fluid
condition. An analogous Lorentz gauge in hydrodynamics is proposed. We have
shown that the vorticity of the fluid is developed whenever the particle local
acceleration of the fluid deviates from the velocity direction. We have also
shown that Lorentz force in electromagnetism corresponds to Euler force in
fluids. Moreover, we have obtained Gauss's, Faraday's and Ampere's -like laws
in Hydrodynamics.",1003.0070v2
2010-03-12,Lorentz symmetry from a random Hamiltonian,"We match the density of energy eigenstates of a local field theory with that
of a random Hamiltonian order by order in a Taylor expansion. In our previous
work we assumed Lorentz symmetry of the field theory, which entered through the
dispersion relation. Here we extend that work to consider a generalized
dispersion relation and show that the Lorentz symmetric case is preferred, in
that the Lorentz symmetric dispersion relation gives a better approximation to
a random Hamiltonian than the other local dispersion relations we considered.",1003.2566v2
2010-04-05,On the Geometry of Conformally Stationary Lorentz Spaces,"In this paper we study several aspects of the geometry of conformally
stationary Lorentz manifolds, and particularly of GRW spaces, due to the
presence of a closed conformal vector field. More precisely, we begin by
extending to these spaces a result of J. Simons on the minimality of cones in
Euclidean space, and apply it to the construction of complete, noncompact
maximal submanifolds of both de Sitter and anti-de Sitter spaces. Then we state
and prove very general Bernstein-type theorems for spacelike hypersurfaces in
conformally stationary Lorentz manifolds, one of which not assuming the
hypersurface to be of constant mean curvature. Finally, we study the strong
$r$-stability of spacelike hypersurfaces of constant $r$-th mean curvature in a
conformally stationary Lorentz manifold of constant sectional curvature,
extending previous results in the current literature.",1004.0617v1
2010-06-21,The Combinatorial Geometry of Q-Gorenstein Quasi-Homogeneous Surface Singularities,"The main result of this paper is a construction of fundamental domains for
certain group actions on Lorentz manifolds of constant curvature. We consider
the simply connected Lie group G~, the universal cover of the group SU(1,1) of
orientation-preserving isometries of the hyperbolic plane. The Killing form on
the Lie group G~ gives rise to a bi-invariant Lorentz metric of constant
curvature. We consider a discrete subgroup Gamma_1 and a cyclic discrete
subgroup Gamma_2 in G~ which satisfy certain conditions. We describe the
Lorentz space form Gamma_1\G~/Gamma_2 by constructing a fundamental domain for
the action of the product of Gamma_1 and Gamma_2 on G~ by (g,h)*x=gxh^{-1}.
This fundamental domain is a polyhedron in the Lorentz manifold G~ with totally
geodesic faces. For a co-compact subgroup the corresponding fundamental domain
is compact. The class of subgroups for which we construct fundamental domains
corresponds to an interesting class of singularities. The bi-quotients of the
form Gamma_1\G~/Gamma_2 are diffeomorphic to the links of quasi-homogeneous
Q-Gorenstein surface singularities.",1006.4021v1
2010-07-07,Gravitational effective action and entanglement entropy in UV modified theories with and without Lorentz symmetry,"We calculate parameters in the low energy gravitational effective action and
the entanglement entropy in a wide class of theories characterized by improved
ultraviolet (UV) behavior. These include i) local and non-local Lorentz
invariant theories in which inverse propagator is modified by higher-derivative
terms and ii) theories described by non-Lorentz invariant Lifshitz type field
operators. We demonstrate that the induced cosmological constant, gravitational
couplings and the entropy are sensitive to the way the theory is modified in
UV. For non-Lorentz invariant theories the induced gravitational effective
action is of the Horava-Lifshitz type. We show that under certain conditions
imposed on the dimension of the Lifshitz operator the couplings of the
extrinsic curvature terms in the effective action are UV finite. Throughout the
paper we systematically exploit the heat kernel method appropriately
generalized for the class of theories under consideration.",1007.1246v2
2010-07-26,Lorentz Gas at a Positive Temperature,"We investigate the evolution of a particle in a Lorentz gas where the
background scatters move and collide with each other. As in the standard
Lorentz gas, we assume that the particle is negligibly light in comparison with
scatters. We show that the average particle speed grows in time as
t^{lambda/(4+lambda)} in three dimensions when the particle-scatter potential
diverges as r^{-lambda} in the small separation limit. The typical displacement
of the particle exhibits a universal linear growth in time independently on the
density of the background gas and the particle-scatter interaction. The
velocity and position distributions approach universal scaling forms. We
determine the former, while for the position distribution we establish
conjecturally exact scaling forms for the one and two-dimensional Lorentz gas.",1007.4589v2
2010-07-30,A quantum field model for tachyonic neutrinos with Lorentz symmetry breaking,"A quantum field model for Dirac-like tachyons respecting a frame-dependent
interpretation rule, and thus inherently breaking Lorentz invariance, is
defined. It is shown how the usual paradoxa ascribed to tachyons, instability
and acausality, are resolved in this model, and it is argued elsewhere that
Lorentz symmetry breaking is necessary to permit perturbative renormalizability
and causality. Elimination of negative-normed states results in only
left-handed particles and right-handed antiparticles, suitable for describing
the neutrino. In this context the neutron beta decay spectrum is calculated
near the end point for large, but not ultrarelativistic preferred frame speed,
assuming a vector weak interaction vertex.",1007.5418v2
2010-09-09,"Lorentz violation, vacuum, cosmic rays, superbradyons and Pamir data","The possibility that Pamir data at very high energy cannot be fully explained
by standard physics has recently led to the suggestion that the peculiar jet
structure observed above ~ 10E16 eV could be due to a suppression of effective
space transverse dimensions. The new pattern considered violates Lorentz
symmetry. We point out that, in models with Lorentz symmetry violation, a
suppression of available transverse energy for jets while conserving
longitudinal momentum can be generated by new forms of energy losses at very
high energy without altering space-time structure. An illustrative example can
be superbradyon emission, where in all cases the superbradyon energy would be
much larger than its momentum times c (speed of light). More generally, such
phenomena could be due to the interaction of the high-energy cosmic ray with
new vacuum and/or particle structure below the 10E-20 cm scale. Scenarios
involving Lorentz symmetry violation but not superbradyons are also briefly
considered.",1009.1853v2
2010-12-18,Generalizations of teleparallel gravity and local Lorentz symmetry,"We analyze the relation between teleparallelism and local Lorentz invariance.
We show that generic modifications of the teleparallel equivalent to general
relativity will not respect local Lorentz symmetry. We clarify the reasons for
this and explain why the situation is different in general relativity. We give
a prescription for constructing teleparallel equivalents for known theories. We
also explicitly consider a recently proposed class of generalized teleparallel
theories, called f(T) theories of gravity, and show why restoring local Lorentz
symmetry in such theories cannot lead to sensible dynamics, even if one gives
up teleparallelism.",1012.4039v2
2010-12-19,Black hole dynamical evolution in a Lorentz-violating spacetime,"We consider the black hole dynamical evolution in the framework of a
Lorentz-violating spacetime endowed with a Schwarzchild-like momentum-dependent
metric. Large deviations from the Hawking-Bekenstein predictions are obtained,
depending on the values of the Lorentz-violating parameter lambda introduced. A
non-trivial evolution comes out, following mainly from the existence of a
non-vanishing minimum mass: for large Lorentz violations, most of the black
hole evaporation takes place in the initial stage, which is then followed by a
stationary stage (whose duration depends on the value of lambda) where the mass
does not change appreciably. Furthermore, for the final stage of evolution, our
model predicts a sweet slow death of the black hole, whose ""slowness"" again
depends on lambda, in contrast with the violent final explosion predicted by
the standard theory.",1012.4180v2
2010-12-28,Asymptotics of physical solutions to the Lorentz-Dirac equation for a planar motion in constant electromagnetic fields,"We present a study of planar physical solutions to the Lorentz-Dirac equation
in a constant electromagnetic field. In this case, we reduced the Lorentz-Dirac
equation to the one second order differential equation. We obtained the
asymptotics of physical solutions to this equation at large proper times. It
turns out that, in the crossed constant uniform electromagnetic field with
vanishing invariants, a charged particle goes to a universal regime at large
times. We found the ratio of momentum components which tends to a constant
determined only by the external field. This effect is essentially due to a
radiation reaction. There is not such an effect for the Lorentz equation in
this field.",1012.5728v4
2011-01-11,Low-energy Phenomenology Of Scalarless Standard-Model Extensions With High-Energy Lorentz Violation,"We consider renormalizable Standard-Model extensions that violate Lorentz
symmetry at high energies, but preserve CPT, and do not contain elementary
scalar fields. A Nambu--Jona-Lasinio mechanism gives masses to fermions and
gauge bosons, and generates composite Higgs fields at low energies. We study
the effective potential at the leading order of the large-N_{c} expansion,
prove that there exists a broken phase and study the phase space. In general,
the minimum may break invariance under boosts, rotations and CPT, but we give
evidence that there exists a Lorentz invariant phase. We study the spectrum of
composite bosons and the low-energy theory in the Lorentz phase. Our approach
predicts relations among the parameters of the low-energy theory. We find that
such relations are compatible with the experimental data, within theoretical
errors. We also study the mixing among generations, the emergence of the CKM
matrix and neutrino oscillations.",1101.2014v2
2011-01-11,Vacuum Cherenkov Radiation In Quantum Electrodynamics With High-Energy Lorentz Violation,"We study phenomena predicted by a renormalizable, CPT invariant extension of
the Standard Model that contains higher-dimensional operators and violates
Lorentz symmetry explicitly at energies greater than some scale Lambda_{L}. In
particular, we consider the Cherenkov radiation in vacuo. In a rather general
class of dispersion relations, there exists an energy threshold above which
radiation is emitted. The threshold is enhanced in composite particles by a
sort of kinematic screening mechanism. We study the energy loss and compare the
predictions of our model with known experimental bounds on Lorentz violating
parameters and observations of ultrahigh-energy cosmic rays. We argue that the
scale of Lorentz violation Lambda_{L} (with preserved CPT invariance) can be
smaller than the Planck scale, actually as small as 10^{14}-10^{15} GeV. Our
model also predicts the Cherenkov radiation of neutral particles.",1101.2019v2
2011-01-14,Superresonance effect from a rotating acoustic black hole and Lorentz symmetry breaking,"We investigate the possibility of the acoustic superresonance phenomenon
(analog to the superradiance in black hole physics), i.e., the amplification of
a sound wave by reflection from the ergoregion of a rotating acoustic black
hole with Lorentz symmetry breaking. For rotating black holes the effect of
superradiance corresponds to the situation where the incident waves has
reflection coefficient greater than one, and energy is extracted from them. For
an acoustic Kerr-like black hole its rate of loss of mass is affected by the
Lorentz symmetry breaking. We also have shown that for suitable values of the
Lorentz violating parameter a wider spectrum of particle wave function can be
scattered with increased amplitude by the acoustic black hole.",1101.2891v2
2011-01-20,Do Fermi-LAT observations really imply very large Lorentz factors in GRB outflows ?,"Recent detections of GeV photons in a few GRBs by Fermi-LAT have led to
strong constraints on the bulk Lorentz factor in GRB outflows. To avoid a large
gamma gamma optical depth, minimum values of the Lorentz factor are estimated
to be as high as 800-1200 in some bursts. Here we present a detailed
calculation of the gamma gamma optical depth taking into account both the
geometry and the dynamics of the jet. In the framework of the internal shock
model, we compute lightcurves in different energy bands and the corresponding
spectrum and we show how the limits on the Lorentz factor can be significantly
lowered compared to previous estimates.",1101.3889v2
2011-03-21,A Lorentz-Covariant Connection for Canonical Gravity,"We construct a Lorentz-covariant connection in the context of first order
canonical gravity with non-vanishing Barbero-Immirzi parameter. To do so, we
start with the phase space formulation derived from the canonical analysis of
the Holst action in which the second class constraints have been solved
explicitly. This allows us to avoid the use of Dirac brackets. In this context,
we show that there is a ""unique"" Lorentz-covariant connection which is
commutative in the sense of the Poisson bracket, and which furthermore agrees
with the connection found by Alexandrov using the Dirac bracket. This result
opens a new way toward the understanding of Lorentz-covariant loop quantum
gravity.",1103.4057v2
2011-05-31,Enhanced CMBR non-Gaussianities from Lorentz violation,"We study the effects of Lorentz symmetry violation on the scalar CMBR
bispectrum. Our quantitative results show that there can be enhancements in the
bispectrum for specific configurations in momentum space, when the modified
dispersion relations resulting from the symmetry breaking violate the adiabatic
condition for a short period of time in the early Universe. The kind of
configurations that are enhanced and the pattern of oscillations in wavenumbers
that generically appear in the bispectrum strictly depend on the form of the
modified dispersion relation, and therefore on the pattern of Lorentz
violation. These effects are found to be distinct from those that appear when
modelling very high-energy (transplanckian) physics via modified boundary
conditions (modified vacuum). In fact, under certain conditions, the
enhancements are even stronger, and possibly open a door to the experimental
study of Lorentz violation through these phenomena.",1106.0040v2
2011-06-03,A new test of local Lorentz invariance using $^{21}$Ne-Rb-K comagnetometer,"We develop a new comagnetometer using $^{21}$Ne atoms with nuclear spin
$I=3/2$ and Rb atoms polarized by spin-exchange with K atoms to search for
tensor interactions that violate local Lorentz invariance. We frequently
reverse orientation of the experiment and search for signals at the first and
second harmonics of the sidereal frequency. We constrain 4 of the 5 spatial
Lorentz-violating coefficients $c^n_{jk}$ that parameterize anisotropy of the
maximum attainable velocity of a neutron at a level of $10^{-29}$, improving
previous limits by 2 to 4 orders of magnitude and placing the most stringent
constrain on deviations from local Lorentz invariance.",1106.0738v2
2011-09-26,Neutrino speed anomaly as signal of Lorentz violation,"We make a reanalysis on the issue of neutrino speed anomaly by taking into
account the newly reported data from the ICARUS experiment and other CNGS
collaborations. We examine the consequence of the Lorentz violation on the
neutrino speed in a new framework of standard model supplement (SMS), and find
that the Lorentz violating parameters are constrained at least one order
stronger than that of the earlier OPERA report. The combination with other
phenomenological considerations puts more stringent constraints on the Lorentz
violation of neutrinos.",1109.6097v3
2011-10-12,"Constraining Lorentz-violating, Modified Dispersion Relations with Gravitational Waves","Modified gravity theories generically predict a violation of Lorentz
invariance, which may lead to a modified dispersion relation for propagating
modes of gravitational waves. We construct a parametrized dispersion relation
that can reproduce a range of known Lorentz-violating predictions and
investigate their impact on the propagation of gravitational waves. A modified
dispersion relation forces different wavelengths of the gravitational wave
train to travel at slightly different velocities, leading to a modified phase
evolution observed at a gravitational-wave detector. We show how such
corrections map to the waveform observable and to the parametrized
post-Einsteinian framework, proposed to model a range of deviations from
General Relativity. Given a gravitational-wave detection, the lack of evidence
for such corrections could then be used to place a constraint on Lorentz
violation. The constraints we obtain are tightest for dispersion relations that
scale with small power of the graviton's momentum and deteriorate for a steeper
scaling.",1110.2720v2
2011-12-02,Einstein's Hydrogen Atom,"In 1905, Einstein formulated his special relativity for point particles. For
those particles, his Lorentz covariance and energy-momentum relation are by now
firmly established. How about the hydrogen atom? It is possible to perform
Lorentz boosts on the proton assuming that it is a point particle. Then what
happens to the electron orbit? The orbit could go through an elliptic
deformation, but it is not possible to understand this problem without quantum
mechanics, where the orbit is a standing wave leading to a localized
probability distribution. Is this concept consistent with Einstein's Lorentz
covariance? Dirac, Wigner, and Feynman contributed important building blocks
for understanding this problem. The remaining problem is to assemble those
blocks to construct a Lorentz-covariant picture of quantum bound states based
on standing waves. It is shown possible to assemble those building blocks using
harmonic oscillators.",1112.0363v1
2011-12-27,Lorentz gauge theory as a model of emergent gravity,"We consider a class of Lorentz gauge gravity theories within Riemann-Cartan
geometry which admits a topological phase in the gravitational sector. The
dynamic content of such theories is determined only by the contortion part of
the Lorentz gauge connection. We demonstrate that there is a unique Lagrangian
that admits propagating spin one mode in correspondence with gauge theories of
other fundamental interactions. Remarkably, despite the R^2 type of the
Lagrangian and non-compact structure of the Lorentz gauge group, the model
possesses rather a positive-definite Hamiltonian. This has been proved in the
lowest order of perturbation theory. This implies further consistent
quantization and leads to renormalizable quantum theory. It is assumed that the
proposed model describes possible mechanism of emergent Einstein gravity at
very early stages of the Universe due to quantum dynamics of contortion.",1112.5952v2
2012-02-15,"Generalized Poincare algebras, Hopf algebras and kappa-Minkowski spacetime","We propose a generalized description for the kappa-Poincare-Hopf algebra as a
symmetry quantum group of underlying kappa-Minkowski spacetime. We investigate
all the possible implementations of (deformed) Lorentz algebras which are
compatible with the given choice of kappa-Minkowski algebra realization. For
the given realization of kappa-Minkowski spacetime there is a unique
kappa-Poincare-Hopf algebra with undeformed Lorentz algebra. We have
constructed a three-parameter family of deformed Lorentz generators with
kappa-Poincare algebras which are related to kappa-Poincare-Hopf algebra with
undeformed Lorentz algebra. Known bases of kappa-Poincare-Hopf algebra are
obtained as special cases. Also deformation of igl(4) Hopf algebra compatible
with the kappa-Minkowski spacetime is presented. Some physical applications are
briefly discussed.",1202.3305v2
2012-02-15,Anisotropic to Isotropic Phase Transitions in the Early Universe,"We propose that the early Universe was not Lorentz symmetric and that a
gradual transition to the Lorentz symmetric phase occurred. An underlying form
of the Dirac equation hints to such a transition for fermions. Fermions were
coupled to space-time in a non-trivial manner such that they were massless in
the Lorentz violating phase. The partition function is used as a transfer
matrix to model this transition on a two level thermodynamics system that
describes how such a transition might have occurred. The system that models
this transition evolves, with temperature, from a state of large to negligible
entropy and this is interpreted as describing the transition to a state with
Lorentz symmetry. In addition to this, analogy is created with the properties
of this system to describe how the fields were massless and how a baryon
asymmetry can be generated in this model.",1202.3668v2
2012-02-25,Lorentz covariant nucleon self-energy decomposition of the nuclear symmetry energy,"Using the Hugenholtz-Van Hove theorem, we derive analytical expressions for
the nuclear symmetry energy $E_{sym}(\rho)$ and its density slope $L(\rho)$ in
terms of the Lorentz covariant nucleon self-energies in isospin asymmetric
nuclear matter. These general expressions are useful for determining the
density dependence of the symmetry energy and understanding the Lorentz
structure and the microscopic origin of the nuclear symmetry energy in
relativistic covariant formulism. As an example, we analyze the Lorentz
covariant nucleon self-energy decomposition of $E_{sym}(\rho)$ and $L(\rho)$
and derive the corresponding analytical expressions within the nonlinear
$\sigma$-$\omega$-$\rho$-$\delta$ relativistic mean field model.",1202.5658v2
2012-03-01,New Chance for Researches on Lorentz Violation,"I present a brief review on the motivation for the study on Lorentz violation
and on some of our studies with phenomenological analysis of Lorentz violation
effects. I also discuss three effective field theory frameworks for Lorentz
violation: the Coleman-Glashow model, the standard model extension (SME), and
the standard model supplement (SMS). The situation of the OPERA ""anomaly"" is
also briefly reviewed, together with some discussion on the superluminality of
neutrinos within the effective field theory frameworks.",1203.0086v3
2012-06-04,High energy neutrino oscillation at the presence of the Lorentz Invariance Violation,"Due to quantum gravity fluctuations at the Planck scale, the space-time
manifold is no longer continuous, but discretized. As a result the Lorentz
symmetry is broken at very high energies. In this article, we study the
neutrino oscillation pattern due to the Lorentz Invariance Violation (LIV), and
compare it with the normal neutrino oscillation pattern due to neutrino masses.
We find that at very high energies, neutrino oscillation pattern is very
different from the normal one. This could provide an possibility to study the
Lorentz Invariance Violation by measuring the oscillation pattern of very high
energy neutrinos from a cosmological distance.",1206.0709v1
2012-06-15,"Ramond-Ramond Cohomology and O(D,D) T-duality","In the name of supersymmetric double field theory, superstring effective
actions can be reformulated into simple forms. They feature a pair of vielbeins
corresponding to the same spacetime metric, and hence enjoy double local
Lorentz symmetries. In a manifestly covariant manner --with regard to O(D,D)
T-duality, diffeomorphism, B-field gauge symmetry and the pair of local Lorentz
symmetries-- we incorporate R-R potentials into double field theory. We take
them as a single object which is in a bi-fundamental spinorial representation
of the double Lorentz groups. We identify cohomological structure relevant to
the field strength. A priori, the R-R sector as well as all the fermions are
O(D,D) singlet. Yet, gauge fixing the two vielbeins equal to each other
modifies the O(D,D) transformation rule to call for a compensating local
Lorentz rotation, such that the R-R potential may turn into an O(D,D) spinor
and T-duality can flip the chirality exchanging type IIA and IIB
supergravities.",1206.3478v2
2012-08-13,Analogue Aharonov-Bohm effect in a Lorentz-violating background,"In this paper we consider the acoustic black hole metrics obtained from a
relativistic fluid under the influence of constant background that violates the
Lorentz symmetry to study the analogue of the Aharonov-Bohm (AB) effect. We
show that the scattering of planar waves by a draining bathtub vortex leads to
a modified AB effect and due to the Lorentz symmetry breaking, the phase shift
persists even in the limit where the parameters associated with the circulation
and draining vanish. In this limit, the Lorentz-violating background forms a
conical defect, which is also responsible for the appearance of the analogue AB
effect.",1208.2615v2
2012-08-31,On the influence of a Coulomb-like potential induced by the Lorentz symmetry breaking effects on the Harmonic Oscillator,"In this work, we obtain bound states for a nonrelativistic spin-half neutral
particle under the influence of a Coulomb-like potential induced by the Lorentz
symmetry breaking effects. We present a new possible scenario of studying the
Lorentz symmetry breaking effects on a nonrelativistic quantum system defined
by a fixed space-like vector field parallel to the radial direction interacting
with a uniform magnetic field along the z-axis. Furthermore, we also discuss
the influence of a Coulomb-like potential induced by Lorentz symmetry violation
effects on the two-dimensional harmonic oscillator.",1208.6482v1
2012-09-25,Unification of Gravity with Electromagnetism,"Principles of Maxwell, Lorentz, Milne, Dirac and Feynman are combined to
unify gravity with electromagnetism.",1209.6290v1
2012-10-05,Spontaneous breaking of Lorentz symmetry for canonical gravity,"In the Ashtekar-Barbero formulation of canonical general relativity based on
an SU(2) connection, Lorentz covariance is a subtle issue which has been the
focus of some debate. Here we present a Lorentz covariant formulation
generalising the notion of a foliation of spacetime to a field of local
observers which specify a time direction only locally. This field spontaneously
breaks the local SO(3,1) symmetry down to a subgroup SO(3); we show that the
apparent symmetry breaking to SO(3) is not in conflict with Lorentz covariance.
We give a geometric picture of our construction as Cartan geometrodynamics and
outline further applications of the formalism of local observers, motivating
the idea that observer space, instead of spacetime, should serve as the
fundamental arena for gravitational physics.",1210.1787v2
2012-10-05,Entanglement properties of a two spin-one particle system under a Lorentz transformation,"We analize the entanglement change, under a Lorentz transformation, of a
system consisting of two spin-one particles, considering different partitions
of the Hilbert space, which has spin and momentum degrees of freedom. We show
that there exists a complete set of states of the spin subspace in which the
entanglement change of any state in the set is zero for all partitions and all
values of the Wigner angle. Moreover, these states only change by a global
phase factor under the Lorentz boost. Within this basis, maximally entangled
invariant states, interesting for quantum information purposes, are explicitly
obtained. On the other hand, the entanglement in the particle- particle
partition is Lorentz invariant, thus protecting the consistency of quantum
correlations and teleportation results. We show how our results may be
generalized to arbitrary spin.",1210.1889v1
2012-11-16,Scheme dependence of quantum gravity on de Sitter background,"We extend our investigation of the IR effects on the local dynamics of matter
fields in quantum gravity. Specifically we clarify how the IR effects depend on
the change of the quantization scheme: different parametrization of the metric
and the matter field redefinition. Conformal invariance implies effective
Lorentz invariance of the matter system in de Sitter space. An arbitrary choice
of the parametrization of the metric and the matter field redefinition does not
preserve the effective Lorentz invariance of the local dynamics. As for the
effect of different parametrization of the metric alone, the effective Lorentz
symmetry breaking term can be eliminated by shifting the background metric. In
contrast, we cannot compensate the matter field redefinition dependence by such
a way. The effective Lorentz invariance can be retained only when we adopt the
specific matter field redefinitions where all dimensionless couplings become
scale invariant at the classical level. This scheme is also singled out by
unitarity as the kinetic terms are canonically normalized.",1211.3878v2
2012-12-26,Effects of a CPT-even and Lorentz-violating nonminimal coupling on the electron-positron scattering,"We propose a new \emph{CPT}-even and Lorentz-violating nonminimal coupling
between fermions and Abelian gauge fields involving the CPT-even tensor
$(K_{F})_{\mu\nu\alpha\beta}$ of the standard model extension. We thus
investigate its effects on the cross section of the electron-positron
scattering by analyzing the process $e^{+}+e^{-}\rightarrow\mu^{+}+\mu^{-}$.
Such a study was performed for the parity-odd and parity-even nonbirefringent
components of the Lorentz-violating $(K_{F})_{\mu\nu\alpha\beta}$ tensor.
Finally, by using experimental data available in the literature, we have
imposed upper bounds as tight as $10^{-12}(eV)^{-1}$ on the magnitude of the
CPT-even and Lorentz-violating parameters while nonminimally coupled.",1212.6230v1
2012-12-28,Modeling rough surfaces with Lorentz equations,"Surfaces sputtered by ion beam bombardment have been known to exhibit
patterns whose behavior is modeled with stochastic partial differential
equations. However, we apply a new approach by the use of the famous Lorentz
equations to simulate and predict such patterns. It has been earlier reported
that at early times, during sputtering, surface displays a chaotic pattern,
with stable domains that nucleate and grow linearly in time until ripples
domains of two different orientations are formed. The numerical solutions of
the Lorentz model, being an unstable and chaotic model, give a pattern similar
to modern surface evolution simulations. The ultimate goal was to predict the
most common surface morphology by constantly varying the parameters of the
Lorentz model and study the effects on the simulated surface patterns. Almost
all of the recent experimentally observed and theoretically predicted
formations are accurately obtainable with this concept.",1212.6483v1
2013-01-16,Toward a real synthesis of quantum and relativity theories: experimental evidence for absolute simultaneity,"We have demonstrated spatially-discontinuous jumps of electrons at a distance
as long as about 1cm. The effect occurs in a modified integer quantum Hall
system consisted of a great number of extended Laughlin-Halperin-type states.
Our observations directly contradict the no-aether Einstein's interpretation of
special relativity together with the Minkowski's model of spacetime. However
they are consistent with the aether-related Lorentz-Poincare's interpretation
that allows absolute simultaneity. We thus strongly challenge the fundamental
status of Lorentz invariance and hence break the basic argument against de
Broglie-Bohm realistic quantum theory. We argue that both de Broglie-Bohm and
Lorentz-Poincare theories are capable of providing a real synthesis of quantum
and relativity theories. The synthesis is of such kind that quantum theory
appears the most fundamental physical theory for which relativity is only a
limiting case. In accordance with this hierarchy, quantum theory naturally
resolves the problem of aether in Lorentz-Poincare's relativity. The aether
could be a deeper Bohm-type undivided quantum pre-space, the relevance of which
directly follows from our observations.",1301.4253v1
2013-03-12,Limits on Violations of Lorentz Symmetry and the Einstein Equivalence Principle using Radio-Frequency Spectroscopy of Atomic Dysprosium,"We report a joint test of local Lorentz invariance and the Einstein
equivalence principle for electrons, using long-term measurements of the
transition frequency between two nearly degenerate states of atomic dysprosium.
We present many-body calculations which demonstrate that the energy splitting
of these states is particularly sensitive to violations of both special and
general relativity. We limit Lorentz violation for electrons at the level of
$10^{-17}$, matching or improving the best laboratory and astrophysical limits
by up to a factor of 10, and improve bounds on gravitational redshift anomalies
for electrons by 2 orders of magnitude, to $10^{-8}$. With some enhancements,
our experiment may be sensitive to Lorentz violation at the level of $9\times
10^{-20}$.",1303.2747v3
2013-03-14,Supersymmetrizing Massive Gravity,"When four scalar fields with global Lorentz symmetry are coupled to gravity
and take a vacuum expectation value breaking diffeomorphism invariance
spontaneously, the graviton becomes massive. This model is supersymmetrized by
considering four N=1 chiral superfields with global Lorentz symmetry. When the
scalar components of the chiral multiplets z^A acquire a vacuum expectation
value, both diffeomorphism invariance and local supersymmetry are broken
spontaneously. The global Lorentz index A becomes identified with the
space-time Lorentz index making the scalar fields z^A vectors and the chiral
spinors psi^A spin-3/2 Rarita-Schwinger fields. The global supersymmetry is
promoted to a local one using the rules of tensor calculus of coupling the N=1
supergravity Lagrangian to the four chiral multiplets. We show that the
spectrum of the model in the broken phase consists of a massive spin-2 field,
two massive spin-3/2 fields with different mass and a massive vector.",1303.3580v3
2013-03-22,Transverse force on a vortex in lattice models of superfluids,"The paper derives the transverse forces (the Magnus and the Lorentz forces)
in the lattice models of superfluids in the continuous approximation. The
continuous approximation restores translational invariance absent in the
original lattice model, but the theory is not Galilean invariant. As a result,
calculation of the two transverse forces on the vortex, Magnus force and
Lorentz force, requires the analysis of two balances, for the true momentum of
particles in the lattice (Magnus force) and for the quasimomentum (Lorentz
force) known from the Bloch theory of particles in the periodic potential.
While the developed theory yields the same Lorentz force, which was well known
before, a new general expression for the Magnus force was obtained. The theory
demonstrates how a small Magnus force emerges in the Josephson-junction array
if the particle-hole symmetry is broken. The continuous approximation for the
Bose--Hubbard model close to the superfluid-insulator transition was developed,
which was used for calculation of the Magnus force. The theory shows that there
is an area in the phase diagram for the Bose--Hubbard model, where the Magnus
force has an inverse sign with respect to that which is expected from the sign
of velocity circulation.",1303.5529v2
2013-04-08,On radiation reaction and the Abraham-Lorentz-Dirac equation,"It is underlined that the Lienard-Wiechert solutions indicate that after the
external force is instantly removed from a small charged particle, the field in
its close neighborhood becomes a Lorentz boosted Coulomb field. It suggests
that the force of the self-field on the particle should instantaneously vanish
after a sudden removal of the external force. A minimal modification of
Abraham-Lorentz-Dirac equation is searched seeking to implement this property.
A term assuring this behavior is added to the equation by maintaining Lorentz
covariance and vanishing scalar product with the four-velocity. The simple
Dirac constant force example does not show runaway acceleration.",1304.2203v1
2013-04-19,Generation of Axion-Like Couplings via Quantum Corrections in a Lorentz Violating Background,"Light pseudoscalars, or axion like particles (ALPs), are much studied due to
their potential relevance to the fields of particle physics, astrophysics and
cosmology. The most relevant coupling of ALPs from the viewpoint of current
experimental searches is to the photon: in this work, we study the generation
of this coupling as an effect of quantum corrections, originated from an
underlying Lorentz violating background. Most interestingly, we show that the
interaction so generated turns out to be Lorentz invariant, thus mimicking the
standard ALPs coupling to the photon that is considered in the experiments.
This consideration implies that violations of spacetime symmetries, much
studied as possible consequences of physics in very high energy scales, might
infiltrate in other realms of physics in unsuspected ways. Additionally, we
conjecture that a similar mechanism can also generate Lorentz invariant
couplings involving scalar particles and photons, playing a possible role in
the phenomenology of Higgs bosons.",1304.5484v2
2013-07-02,"Exact Rotational Space-time Transformations, Davies-Jennison Experiments and Limiting Lorentz-Poincaré Invariance","Jennison deduced from the rotational experiments that a rotating radius $r_r$
measured by the rotating observer is contracted by $r_r = r(1-\om^2
r^2/c^2)^{1/2}$, compared with the radius $r$ measured in an inertial frame.
This conclusion differs from the result based on Lorentz transformations. Since
rotational frames are not equivalent to inertial frames, we analyze the
rotational experiments by using the exact rotational space-time transformations
rather than the Lorentz transformations. We derive exact rotational
transformations on the basis of the principle of limiting Lorentz-Poincar\'e
invariance. The exact rotational transformations form a pseudo-group rather
than the usual Lie group. They support Jennison's contraction of a rotating
radius and are consistent with two Davies-Jennison experiments. We also suggest
new experimental tests for the exact rotational transformations.",1307.0662v1
2013-07-19,Tests of Lorentz Invariance Using High Energy Astrophysics Observations,"High-energy astrophysics observations provide the best possibilities to
detect a very small violation of Lorentz invariance, such as may be related to
the structure of space-time near the Planck scale. I discuss the possible
signatures of Lorentz invariance violation that can be manifested by observing
the spectra, polarization, and timing of gamma-rays from active galactic nuclei
and gamma-ray bursts. Other sensitive tests are provided by observations of the
spectra of ultrahigh-energy cosmic rays and very high-energy neutrinos. I also
discuss a new time-of-flight analysis of observations of GRB 090510 by the
Fermi gamma-ray Space Telescope. These results, based on high-energy
astrophysical observations, have fundamental implications for space-time
physics and quantum gravity models.",1307.5212v1
2013-07-23,Strong Binary Pulsar Constraints on Lorentz Violation in Gravity,"Binary pulsars are excellent laboratories to test the building blocks of
Einstein's theory of General Relativity. One of these is Lorentz symmetry which
states that physical phenomena appear the same for all inertially moving
observers. We study the effect of violations of Lorentz symmetry in the orbital
evolution of binary pulsars and find that it induces a much more rapid decay of
the binary's orbital period due to the emission of dipolar radiation. The
absence of such behavior in recent observations allows us to place the most
stringent constraints on Lorentz violation in gravity, thus verifying one of
the cornerstones of Einstein's theory much more accurately than any previous
gravitational observation.",1307.6219v3
2014-01-13,On the use of energy loss mechanisms to constrain Lorentz invariance violations,"In light of recent and probably upcoming observations of very high energy
astroparticles, such as those reported by the IceCube collaboration, we
readdress the energy loss mechanism by Lorentz violating particles. We
analytically show that Cohen-Glashow's formula for energy loss is connected
with a Poisson distribution for the number of decays, whose large fluctuations
prevent placing bounds on Lorentz invariance violations. However, this model
ignores the sharp change in the decay width after each process. We propose
replacing Poisson statistics with a new distribution that takes this into
account. We study the average final energy and its fluctuations according to
the new statistics, contrasting it with Cohen-Glashow's result, and discussing
the reliability of energy loss mechanisms to constrain violations of Lorentz
invariance.",1401.2964v2
2014-01-26,Forensic Statistics and Justice: the Leiden Consensus,"Between 26 and 29 April 2011 a four-day interdisciplinary workshop ""Science
meets Law"" was held at the Lorentz Center (University of Leiden, NL). It was
organised by the Lorentz Center in collaboration with the Netherlands Institute
for Advanced Study in the Humanities and Social Sciences (""NIAS"", Wassenaar,
NL). The programme was prepared by Richard Gill and Johannes F. Nijboer and
connected to Richard Gill's 2010-2011 stay at NIAS as Distinguished Lorentz
Fellow.
  This document was prepared by three of us and represents our personal
synthesis of the discussions which took place during the meeting. Comments are
welcome.",1401.6640v1
2014-01-31,The CTA Sensitivity to Lorentz-Violating Effects on the Gamma-Ray Horizon,"The arrival of TeV-energy photons from distant galaxies is expected to be
affected by their QED interaction with intergalactic radiation fields through
electron-positron pair production. In theories where high-energy photons
violate Lorentz symmetry, the kinematics of the process $\gamma +
\gamma\rightarrow e^+ + e^-$ is altered and the cross-section suppressed.
Consequently, one would expect more of the highest-energy photons to arrive if
QED is modified by Lorentz violation than if it is not. We estimate the
sensitivity of Cherenkov Telescope Array (CTA) to changes in the $\gamma$-ray
horizon of the Universe due to Lorentz violation, and find that it should be
competitive with other leading constraints.",1401.8178v2
2014-02-04,"Isgur-Wise functions, Bjorken-Uraltsev Sum Rules and their Lorentz group interpretation, In Memoriam Nikolai Uraltsev","In the heavy quark limit of QCD, using the Operator Product Expansion and the
non-forward amplitude, as proposed by Nikolai Uraltsev, we formulate sum rules
that generalize Bjorken and Uraltsev sum rules. We recover the Uraltsev lower
bound for the slope of the Isgur-Wise (IW) function, that we generalize to
higher derivatives. We show that these results have a clear interpretation in
terms of the Lorentz group, since the IW function is given by an overlap
between the initial and final light clouds, related by Lorentz transformations.
Both the Lorentz group and the Sum Rules approach are equivalent. Moreover, we
formulate an integral representation of the IW function with a positive
measure. Inverting this integral formula, we obtain the measure in terms of the
IW function, allowing to formulate criteria to decide if a given ansatz for the
IW function is compatible or not with the sum rule constraints. We compare
these theoretical constraints to some forms proposed in the literature.",1402.0798v1
2014-02-08,Graviton Propagation in an Asymmetric Warped Background: Lorentz Violation and the Null Energy Condition,"The graviton propagation in an asymmetric background is studied. The
background is a configuration in the six-dimensional Salam-Sezgin model, in
which a 3-form H-field turned on [JHEP 0910(2009)086]. The compact dimensions
form a cylindrical space with branes as boundaries. The background gets
asymmetry due to the H-field and violates the Lorentz symmetry. We derive the
graviton equation in this background and show that it gets massless mode
traveling with superluminal speed. A tower of K-K modes exists with a mass gap.
On the other hand, it is known that breaking the Lorentz symmetry on an
asymmetric background is constrained by the null energy condition. This no-go
theorem doesn't work well in six-dimensional space-times and by this model we
provide a counterexample for which the null energy condition is satisfied while
the Lorentz symmetry is gravitationally violated.",1402.1838v2
2014-04-12,"The low-density limit of the Lorentz gas: periodic, aperiodic and random","The Lorentz gas is one of the simplest, most widely used models to study the
transport properties of rarified gases in matter. It describes the dynamics of
a cloud of non-interacting point particles in an infinite array of fixed
spherical scatterers. More than one hundred years after its conception, it is
still a major challenge to understand the nature of the kinetic transport
equation that governs the macroscopic particle dynamics in the limit of low
scatterer density (the Boltzmann-Grad limit). Lorentz suggested that this
equation should be the linear Boltzmann equation. This was confirmed in three
celebrated papers by Gallavotti, Spohn, and Boldrighini, Bunimovich and Sinai,
under the assumption that the distribution of scatterers is sufficiently
disordered. In the case of strongly correlated scatterer configurations (such
as crystals or quasicrystals), we now understand why the linear Boltzmann
equation fails and what to substitute it with. A particularly striking feature
of the periodic Lorentz gas is a heavy tail for the distribution of free path
lengths, with a diverging second moment, and superdiffusive transport in the
limit of large times.",1404.3293v1
2014-04-18,Maxwell-Chern-Simons vortices in a CPT-odd Lorentz-violating Higgs Electrodynamics,"We have studied BPS vortices in a CPT-odd and Lorentz-violating
Maxwell-Chern-Simons-Higgs (MCSH) electrodynamics attained from the dimensional
reduction of the Carroll-Field-Jackiw-Higgs model. The Lorentz-violating
parameter induces a pronounced behavior at origin (for the magnetic/electric
fields and energy density) which is absent in the MCSH vortices. For some
combination of the Lorentz-violating coefficients there always exist a
sufficiently large winding number $n_{0}$ such that for all $% |n|\geq |n_{0}|$
the magnetic field flips its signal, yielding two well defined regions with
opposite magnetic flux. However, the total magnetic flux remains quantized and
proportional to the winding number.",1404.4678v1
2014-07-17,External stability for Spherically Symmetric Solutions in Lorentz Breaking Massive Gravity,"We discuss spherically symmetric solutions for point-like sources in
Lorentz-breaking massive gravity theories. This analysis is valid for
  St\""uckelberg's effective field theory formulation, for Lorentz Breaking
Massive Bigravity and general extensions of gravity leading to an extra term
$-Sr^{\gamma}$ added to the Newtonian potential. The approach consists in
analyzing the stability of the geodesic equations, at the first order
(deviation equation). The main result is a strong constrain in the space of
parameters of the theories. This motivates higher order analysis of geodesic
perturbations in order to understand if a class of spherically symmetric
Lorentz-breaking massive gravity solutions, for self-gravitating systems,
exists. Stable and phenomenologically acceptable solutions are discussed in the
no-trivial case $S\neq 0$.",1407.4840v3
2014-07-23,Geometric quantum phases from Lorentz symmetry breaking effects in the cosmic string spacetime,"By starting from the modified Maxwell theory coupled to gravity, the arising
of geometric quantum phases in the relativistic and nonrelativistic quantum
dynamics of a Dirac neutral particle from the effects of the violation of the
Lorentz symmetry in the cosmic string spacetime is investigated. It is shown
that the Dirac equation can be written in terms of an effective metric and a
relativistic geometric phase stems from the topology of the cosmic string
spacetime and the Lorentz symmetry breaking effects. Further, the
nonrelativistic limit of the Dirac equation is discussed and it is shown that
both Lorentz symmetry breaking effects and the topology of the defect yields a
phase shift in the wave function of the nonrelativistic spin-1/2 particle.",1407.6279v1
2014-07-30,Imaging of Shear Waves Induced by Lorentz Force in Soft Tissues,"This study presents the first observation of elastic shear waves generated in
soft solids using a dynamic electromagnetic field. The first and second
experiments of this 5 study showed that Lorentz force can induce a displacement
in a soft phantom and that this displacement was detectable by an ultrasound
scanner using speckle-tracking algorithms. For a 100 mT magnetic field and a 10
ms, 100 mA peak-to-peak electrical burst, the displacement reached a magnitude
of 1 um. In the third experiment, we showed that Lorentz force can induce shear
waves in a phantom. A physical model 10 using electromagnetic and elasticity
equations was proposed. Computer simulations were in good agreement with
experimental results. The shear waves induced by Lorentz force were used in the
last experiment to estimate the elasticity of a swine liver sample.",1407.8196v1
2014-08-21,Topological charged BPS vortices in Lorentz-violating Maxwell-Higgs electrodynamics,"We have performed a complete study of BPS vortex solutions in the Abelian
sector of the standard model extension (SME). Specifically, we have coupled the
SME electromagnetism with a Higgs field which is supplemented with a
Lorentz-violating CPT-even term. We have verified that Lorentz violation (LV)
belonging to the Higgs sector allows to interpolate between some well known
models like, Maxwell-Higgs, Chern-Simons-Higgs and Maxwell-Chern-Simons-Higgs.
We can also observed that the electrical charged density distribution is
nonnull in both CPT-even and CPT-odd models; however, the total electric charge
in the CPT-even case is null, whereas in the CPT-odd one it is proportional to
the quantized magnetic flux. The following general results can be established
in relation to the LV introduced in the Higgs sector: it changes the vortex
ansatz and the gauge field boundary conditions. A direct consequence is that
the magnetic flux, besides being proportional to the winding number, also
depends explicitly on the Lorentz-violation belonging to the Higgs sector.",1408.5168v2
2014-09-01,"Higher-order Lorentz-invariance violation, quantum gravity and fine-tuning","The issue of Lorentz fine-tuning in effective theories containing
higher-order operators is studied. To this end, we focus on the Myers-Pospelov
extension of QED with dimension-five operators in the photon sector and
standard fermions. We compute the fermion self-energy at one-loop order
considering its even and odd $CPT$ contributions. In the even sector we find
small radiative corrections to the usual parameters of QED which also turn to
be finite. In the odd sector the axial operator is shown to contain
unsuppressed effects of Lorentz violation leading to a possible fine-tuning. We
use dimensional regularization to deal with the divergencies and a generic
preferred four-vector. Taking the first steps in the renormalization procedure
for Lorentz violating theories we arrive to acceptable small corrections
allowing to set the bound $\xi<6 \times10^{-3}$.",1409.0508v2
2014-09-04,"Classical kinematics for isotropic, minimal Lorentz-violating fermion operators","In this article the classical, relativistic Lagrangian based on the isotropic
fermion sector of the Lorentz-violating (minimal) Standard-Model Extension is
considered. The motion of the associated classical particle in an external
electromagnetic field is studied and the evolution of its spin, which is
introduced by hand, is investigated. It is shown that the particle travels
along trajectories that are scaled versions of the standard ones. Furthermore
there is no spin precession due to Lorentz violation, but the rate is modified
at which the longitudinal and transverse spin components transform into each
other. This demonstrates that it is practical to consider classical physics
within such an isotropic Lorentz-violating framework and it opens the pathway
to study a curved background in that context.",1409.1539v3
2014-10-03,Hydrogen and muonic-Hydrogen Atomic Spectra in Non-commutative Space-Time,"Comparing electronic Hydrogen with muonic Hydrogen shows that the discrepancy
in measurement of the Lamb shift in the both systems are relatively of order of
$(\frac{m_\mu}{m_e})^{4-5}$. We explore the spectrum of Hydrogen atom in
noncommutative $QED$ to compare the noncommutative effects on the both bound
states. We show that in the Lorentz violating noncommutative QED the ratio of
NC-corrections is $(\frac{m_\mu}{m_e})^3$ while in the Lorentz conserving NCQED
is $(\frac{m_\mu}{m_e})^5$. An uncertainty about $1 \,Hz\ll 3\,kHz$ in the Lamb
shift of Hydrogen atom leads to an NC correction about $10 \,MHz$ in the
Lorentz violating noncommutative QED and about $400 \,GHz$ in the Lorentz
conserving noncommutative QED.",1410.0836v2
2014-12-10,Question of Lorentz invariance in muon decay,"Possibilities to test the Lorentz invariance of the weak interaction in muon
decay are considered. We derive the direction-dependent muon-decay rate with a
general Lorentz-violating addition to the W-boson propagator. We discuss
measurements of the directional and boost dependence of the Michel parameters
and of the muon lifetime as a function of absolute velocity. The total
muon-decay rate in the Lorentz-violating Standard Model Extension is addressed.
Suggestions are made for dedicated (re)analyses of the pertinent data and for
future experiments.",1412.3257v3
2014-12-16,On the influence of a Rashba-type coupling induced by Lorentz-violating effects on a Landau system for a neutral particle,"We study a possible scenario of the Lorentz symmetry violation background
that allows us to build an analogue of the Landau system for a nonrelativistic
Dirac neutral particle interacting with a field configuration of crossed
electric and magnetic fields. We also discuss the arising of analogues of the
Rashba coupling, the Zeeman term and the Darwin term from the Lorentz symmetry
breaking effects, and the influence of these terms on the analogue of the
Landau system confined to a two-dimensional quantum ring. Finally, we show that
this analogy with the Landau system confined to a two-dimensional quantum ring
allows us to establish an upper bound for the Lorentz symmetry breaking
parameters.",1412.5078v1
2015-01-05,Lorentz invariance violation with gamma rays,"The assumption of Lorentz invariance is one of the founding principles of
Modern Physics and violation of it would have profound implications to our
understanding of the universe. For instance, certain theories attempting a
unified theory of quantum gravity predict there could be an effective
refractive index of the vacuum; the introduction of an energy dependent
dispersion to photons could in turn lead to an observable Lorentz invariance
violation signature. Whilst a very small effect on local scales the effect will
be cumulative, and so for very high energy particles that travel very large
distances the difference in arrival times could become sufficiently large to be
detectable. This proceedings will look at testing for such Lorentz invariance
violation (LIV) signatures in the astronomical lightcurves of gamma-ray
emitting objects, with particular notice being given to the prospects for LIV
testing with, the next generation observatory, the Cherenkov Telescope Array.",1501.00824v1
2015-01-25,Constraining the bulk Lorentz factor from the photosphere emission,"We propose a direct and model-independent method to constrain the Lorentz
factor of a relativistically expanding object, like gamma-ray bursts. Only the
measurements, such as thermal component of the emission, the distance and the
variable time scale of the light curve, are used. If the uncertainties are
considered, we will obtain lower limits of the Lorentz factor instead. We apply
this method to GRB 090618 and get a lower limit of the Lorentz factor to be 22.
The method can be used to any relativistically moving object, such as gamma-ray
bursts, blazars, and soft gamma-ray repeaters, providing the thermal component
of the emission being observed.",1501.06132v1
2015-02-23,Testing Lorentz invariance in orbital electron capture,"Searches for Lorentz violation were recently extended to the weak sector, in
particular neutron and nuclear $\beta$ decay [1]. From experiments on forbidden
$\beta$-decay transitions strong limits in the range of $10^{-6}$-$10^{-8}$
were obtained on Lorentz-violating components of the $W$-boson propagator [2].
In order to improve on these limits strong sources have to be considered. In
this Brief Report we study isotopes that undergo orbital electron capture and
allow experiments at high decay rates and low dose. We derive the expressions
for the Lorentz-violating differential decay rate and discuss the options for
competitive experiments and their required precision.",1502.06473v1
2015-03-13,Chern-Simons Theory in SIM(1) Superspace,"In this paper, we will analyse a three dimensional supersymmetric
Chern-Simons theory in SIM(1) superspace formalism. The breaking of the Lorentz
symmetry down to the SIM(1) symmetry, breaks half the supersymmetry of the
Lorentz invariant theory. So, the supersymmetry of the Lorentz invariant
Chern-Simons theory with N=1 supersymmetry will break down to N=1/2
supersymmetry, when the Lorentz symmetry is broken down to the SIM(1) symmetry.
First, we will write the Chern-Simons action using SIM(1) projections of N=1
superfields. However, as the SIM(1) transformations of these projections are
very complicated, we will define SIM(1) superfields which transform simply
under SIM(1) transformations. We will then express the Chern-Simons action
using these SIM(1) superfields. Furthermore, we will analyse the gauge symmetry
of this Chern-Simons theory. This is the first time that a Chern-Simons theory
with N=1/2 supersymmetry will be constructed on a manifold without a boundary.",1503.04761v1
2015-04-03,Appearance of the prolate and the toroidal magnetic field dominated stars - Analytic approach,"We have analyzed magnetized equilibrium states and showed a condition for
appearance of the prolate and the toroidal magnetic field dominated stars by
analytic approaches. Both observations and numerical stability analysis support
that the magnetized star would have the prolate and the large internal toroidal
magnetic fields. In this context, many investigations concerning magnetized
equilibrium states have tried to obtain the prolate and the toroidal dominant
solutions, but many of them have failed to obtain such configurations. Since
the Lorentz force is a cross product of current density and magnetic field, the
prolate shaped configurations and the large toroidal magnetic fields in stars
require a special relation between current density and the Lorentz force. We
have analyzed simple analytical solutions and found that the prolate and the
toroidal dominant configuration require non force-free toroidal current density
that flows in the opposite direction with respect to the bulk current within
the star. Such current density results in the Lorentz force which makes the
stellar shape prolate. Satisfying this special relation between the current
density and the Lorentz force is a key for appearance of the prolate and the
toroidal magnetic field dominated magnetized star.",1504.00713v1
2015-04-13,Optical Flashes from Internal Pairs Formed in Gamma-Ray Burst Afterglows,"We develop a numerical formalism for calculating the distribution with energy
of the (internal) pairs formed in a relativistic source from unscattered
MeV--TeV photons.
  For GRB afterglows, this formalism is more suitable if the relativistic
reverse-shock that energizes the ejecta is the source of the GeV photons.
  The number of pairs formed is set by the source GeV output (calculated from
the Fermi-LAT fluence), the unknown source Lorentz factor, and the unmeasured
peak energy of the LAT spectral component.
  We show synchrotron and inverse-Compton light-curves expected from pairs
formed in the shocked medium and identify some criteria for testing a pair
origin of GRB optical counterparts.
  Pairs formed in bright LAT afterglows with a Lorentz factor in the few
hundreds may produce bright optical counterparts (R < 10) lasting for up to one
hundred seconds.
  The number of internal pairs formed from unscattered seed photons decreases
very strongly with the source Lorentz factor, thus bright GRB optical
counterparts cannot arise from internal pairs if the afterglow Lorentz factor
is above several hundreds.",1504.03205v1
2015-04-13,Search for Lorentz invariance violation through tests of the gravitational inverse square law at short-ranges,"A search for sidereal variations in the non-Newtonian force between two
tungsten plates separated at millimeter ranges sets experimental limits on
Lorentz invariance violation involving quadratic couplings of Riemann
curvature. We show that the Lorentz invariance violation force between two
finite flat plates is dominated by the edge effects, which includes a
suppression effect leading to lower limits than previous rough estimates. From
this search, we determine the current best constraints of the Lorentz
invariance violating coefficients at a level of $10^{-8}$ m$^{2}$.",1504.03280v1
2015-04-23,Generation of geometrical phases and persistent spin currents in 1-dimensional rings by Lorentz-violating terms,"We have demonstrated that Lorentz-violating terms stemming from the fermion
sector of the SME are able to generate geometrical phases on the wave function
of electrons confined in 1-dimensional rings, as well as persistent spin
currents, in the total absence of electromagnetic fields. We have explicitly
evaluated the eigenenergies and eigenspinors of the electrons modified by the
Lorentz-violating terms, using them to calculate the dynamic and the
Aharonov-Anandan phases in the sequel. The total phase presents a pattern very
similar to the Aharonov-Casher phase accumulated by electrons in rings under
the action of the Rashba interaction. Finally, the persistent spin current were
carried out and used to impose upper bounds on the Lorentz-violating
parameters.",1504.06027v2
2015-04-27,Relativistic scalar particle subject to a confining potential and Lorentz symmetry breaking effects in the cosmic string spacetime,"The behaviour of a relativistic scalar particle subject to a scalar potential
under the effects of the violation of the Lorentz symmetry in the cosmic string
spacetime is discussed. It is considered two possible scenarios of the Lorentz
symmetry breaking in the CPT-even gauge sector of the Standard Model Extension
defined by a tensor $\left(K_{F}\right)_{\mu\nu\alpha\beta}$. Then, by
introducing a scalar potential as a modification of the mass term of the
Klein-Gordon equation, it is shown that the Klein-Gordon equation in the cosmic
string spacetime is modified by the effects of the Lorentz symmetry violation
backgrounds and bound state solution to the Klein-Gordon equation can be
obtained.",1504.07262v1
2015-05-04,New Branches of Massive Gravity,"The basic building block for Lorentz invariant and ghost free massive gravity
is the square root of the combination $g^{-1}\eta\,$, where $g^{-1}$ is the
inverse of the physical metric and $\eta$ is a reference metric. Since the
square root of a matrix is not uniquely defined, it is possible to have
physically inequivalent potentials corresponding to different branches. We show
that around Minkowski background the only perturbatively well defined branch is
the potential proposed by de Rham, Gabadadze and Tolley. On the other hand, if
Lorentz symmetry is broken spontaneously, other potentials exist with a
standard perturbative expansion. We show this explicitly building new Lorentz
invariant, ghost-free massive gravity potentials for theories that in the
background preserve rotational invariance, but break Lorentz boosts.",1505.00632v1
2015-05-06,Stationary black holes: Large $D$ analysis,"We consider the effective theory of the large D stationary black hole. By
solving Einstein equation with a cosmological constant using the 1/D expansion
in near zone of a black hole we obtain the effective equation for the
stationary black hole. The effective equation describes the Myers-Perry black
hole, bumpy black holes and, possibly, the black ring solution as its
solutions. In this effective theory the black hole is represented as the
embedded membrane in the background, i.e., Minkowski or Anti-de Sitter
spacetime and its mean curvature is given by the redshifted surface gravity by
the background geometry and the local Lorentz boost. The local Lorentz boost
property of the effective equation is observed also in the metric. In fact we
show that the leading order metric of the Einstein equation in the 1/D
expansion is generically regarded as the Lorentz boosted Schwarzschild black
hole. We apply this Lorentz boost property of the stationary black hole
solution to solve the perturbation equation. As a result we obtain the analytic
formula for the quasinormal mode of the singly rotating Myers-Perry black hole
in the 1/D expansion.",1505.01282v2
2015-05-07,"The axial anomaly, dimensional regularization and Lorentz-violating QED","In order to treat loops in the Lorentz-violating QED model, we present a
derivation of the QED axial anomaly that specifically highlights the infrared
origin of the effect. This is done using dimensional regularization while
treating $\gamma_5$ as a spectator. This enables us to revisit aspects in the
fermionic sector of Lorentz-violating QED which have analogous structure to the
axial anomaly. In particular, it is shown that both the Chern-Simons and photon
mass operators are not induced in the one loop effective action. At lowest
order in the Lorentz-violating parameter, we can define a non-relativistic
potential that captures the effects of vacuum polarization. This leads to a
Zeeman-like effect in vacuum which lifts the two-fold degeneracy of the
hydrogen atom S-orbitals.",1505.01754v2
2015-05-09,Parametric Realization of the Lorentz Transformation Group in Pseudo-Euclidean Spaces,"The Lorentz transformation group $SO(m,n)$ is a group of Lorentz
transformations of order $(m,n)$, that is, a group of special linear
transformations in a pseudo-Euclidean space of signature $(m,n)$ that leave the
pseudo-Euclidean inner product invariant. A parametrization of $SO(m,n)$ is
presented, giving rise to the composition law of Lorentz transformations of
order $(m,n)$ in terms of parameter composition. The parameter composition, in
turn, gives rise to a novel group-like structure called a bi-gyrogroup.
Bi-gyrogroups form a natural generalization of gyrogroups where the latter form
a natural generalization of groups. Like the abstract gyrogroup, the abstract
bi-gyrogroup can play a universal computational role which extends far beyond
the domain of pseudo-Euclidean spaces.",1505.02301v1
2015-06-04,"Lorentz and CPT tests with hydrogen, antihydrogen, and related systems","The potential of precision spectroscopy as a tool in systematic searches for
effects of Lorentz and CPT violation is investigated. Systems considered
include hydrogen, antihydrogen, deuterium, positronium, and hydrogen molecules
and molecular ions. Perturbative shifts in energy levels and key transition
frequencies are derived, allowing for Lorentz-violating operators of arbitrary
mass dimensions. Observable effects are deduced from various direct
measurements, sidereal and annual variations, comparisons among species, and
gravitational responses. We use existing data to place new and improved
constraints on nonrelativistic coefficients for Lorentz and CPT violation, and
we provide estimates for the future attainable reach in direct spectroscopy of
the various systems or tests with hydrogen and deuterium masers. The results
reveal prospective sensitivities to many coefficients unmeasured to date, along
with potential improvements of a billionfold or more over certain existing
results.",1506.01706v1
2015-08-04,From the Lorentz Group to the Celestial Sphere,"In these lecture notes we review the isomorphism between the (connected)
Lorentz group and the set of conformal transformations of the sphere. More
precisely, after establishing the main properties of the Lorentz group, we show
that it is isomorphic to the group SL(2,C) of complex 2 by 2 matrices with unit
determinant. We then classify conformal transformations of the sphere, define
the notion of null infinity in Minkowski space-time, and show that the action
of Lorentz transformations on the celestial spheres at null infinity is
precisely that of conformal transformations. In particular, we discuss the
optical phenomena observed by the pilots of the ""Millenium Falcon"" during the
jump to lightspeed.",1508.00920v3
2015-08-27,Constraints on Lorentz violation from gravitational Cherenkov radiation,"Limits on gravitational Cherenkov radiation by cosmic rays are obtained and
used to constrain coefficients for Lorentz violation in the gravity sector
associated with operators of even mass dimensions, including
orientation-dependent effects. We use existing data from cosmic-ray telescopes
to obtain conservative two-sided constraints on 80 distinct Lorentz-violating
operators of dimensions four, six, and eight, along with conservative one-sided
constraints on three others. Existing limits on the nine minimal operators at
dimension four are improved by factors of up to a billion, while 74 of our
explicit limits represent stringent first constraints on nonminimal operators.
Prospects are discussed for future analyses incorporating effects of Lorentz
violation in the matter sector, the role of gravitational Cherenkov radiation
by high-energy photons, data from gravitational-wave observatories, the
tired-light effect, and electromagnetic Cherenkov radiation by gravitons.",1508.07007v1
2015-09-14,Topological self-dual configurations in a Lorentz-violating gauged O(3) sigma model,"We have studied the existence of topological Bogomol'nyi-Prasad-Sommerfield
or self-dual configurations in a Lorentz-violating gauged $O(3)$ nonlinear
sigma model, where $CPT$-even Lorentz-violating (LV) terms were introduced in
both the gauge and $\sigma $% -field sectors. As happens in the usual gauged
$\sigma $ model, purely magnetic self-dual configurations are allowed,
maintaining some qualitative features of the standard ones. In a more involved
configuration, Lorentz violation provides new self-dual magnetic solutions
carrying an electric field but a null total electric charge. In both cases, the
total energy of the self-dual configurations turns out to be proportional to
the topological charge of the model and to the LV parameters introduced in the
$% \sigma $ sector. It is shown that the LV terms yield magnetic flux reversion
as well.",1509.04056v3
2015-09-29,Lorentz and CPT Violation in Top-Quark Production and Decay,"The prospects are explored for testing Lorentz and CPT symmetry in the
top-quark sector. We present the relevant Lagrange density, discuss physical
observables, and describe the signals to be sought in experiments. For
top-antitop pair production via quark or gluon fusion with subsequent
semileptonic or hadronic decays, we obtain the matrix element in the presence
of Lorentz violation using the narrow-width approximation. The issue of testing
CPT symmetry in the top-quark sector is also addressed. We demonstrate that
single-top production and decay is well suited to a search for CPT violation,
and we present the matrix elements for single-top production in each of the
four tree-level channels. Our results are applicable to searches for Lorentz
violation and studies of CPT symmetry in collider experiments, including
notably high-statistics top-antitop and single-top production at the Large
Hadron Collider.",1509.08929v1
2015-10-03,The Effective Gravitational Theory at Large Scale with Lorentz Violation,"The dipole anomaly in the power spectrum of CMB may indicate that the Lorentz
boost invarianc is violated at cosmic scale. We assume that the Lorentz
symmetry is violated partly from the scale of galaxy. We employ the symmetry of
very special relativity as an example to illustrate the Lorentz violation
effect by constructing the corresponding gauge theories as the effective
gravitational theory at the large scale. We find the common feather of these
gravitation models is the non-triviality of spacetime torsion and contorsion
even if the matter source is of only scalar matter. The presence of non-trivial
contorsion contributes an effective enenrgy-momentum distribution which may
account for part of dark matter effect.",1510.00814v3
2015-10-20,Dynamical ambiguities in models with spontaneous Lorentz violation,"Spontaneous Lorentz violation is a viable mechanism to look for Planck scale
physics. In this work, we study spontaneous Lorentz violation models, in flat
spacetime, where a vector field produces such a violation and matter is modeled
by a complex scalar field. We show that it is possible to construct a Hamilton
density for which the evolution respects the dynamical constraints. However, we
also find that the initial data, as required by standard field theory, does not
determine the fields evolution in a unique way. In addition, we present some
examples where the physical effects of such ambiguities can be recognized. As a
consequence, the proposals in which the electromagnetic and gravitational
interactions emerge from spontaneous Lorentz violation are challenged.",1510.05999v2
2015-11-02,Local boundary regularity for the Navier-Stokes equations in nonendpoint borderline Lorentz spaces,"We prove local regularity up to flat part of boundary, for certain classes of
distributional solutions that are $L_{\infty}L^{3,q}$ with $q$ finite.",1511.00626v1
2015-11-17,Concurrent tests of Lorentz invariance in $β$-decay experiments,"Modern experiments on neutron and allowed nuclear $\beta$ decay search for
new semileptonic interactions, beyond the ``left-handed'' electroweak force. We
show that ongoing and planned $\beta$-decay experiments, with isotopes at rest
and in flight, can be exploited as sensitive tests of Lorentz invariance. The
variety of correlations that involve the nuclear spin, the direction of the
emitted $\beta$ particle, and the recoil direction of the daughter nucleus
allow for relatively simple experiments that give direct bounds on Lorentz
violation. The pertinent observables are decay-rate asymmetries and their
dependence on sidereal time. We discuss the potential of several asymmetries
that together cover a large part of the parameter space for Lorentz violation
in the gauge sector. High counting statistics is required.",1511.05400v1
2016-01-13,Generation of higher derivatives operators and electromagnetic wave propagation in a Lorentz-violation scenario,"We study the perturbative generation of higher-derivative operators as
corrections to the photon effective action, which are originated from a Lorentz
violation background. Such corrections are obtained, at one-loop order, through
the proper-time method, using the zeta function regularization. We focus over
the lowest order corrections and investigate their influence in the propagation
of electromagnetic waves through the vacuum, in the presence of a strong,
constant magnetic field. This is a setting of experimental relevance, since it
bases active efforts to measure non linear electromagnetic effects. After
surprising cancellations of Lorentz violating corrections to the Maxwell's
equation, we show that no effects of the kind of Lorentz violation we consider
can be detected in such a context.",1601.03298v2
2016-01-20,Littlewood-Paley Characterizations of Anisotropic Hardy-Lorentz Spaces,"Let $p\in(0,1]$, $q\in(0,\infty]$ and $A$ be a general expansive matrix on
$\mathbb{R}^n$. Let $H^{p,q}_A(\mathbb{R}^n)$ be the anisotropic Hardy-Lorentz
spaces associated with $A$ defined via the non-tangential grand maximal
function. In this article, the authors characterize $H^{p,q}_A(\mathbb{R}^n)$
in terms of the Lusin-area function, the Littlewood-Paley $g$-function or the
Littlewood-Paley $g_\lambda^*$-function via first establishing an anisotropic
Fefferman-Stein vector-valued inequality in the Lorentz space
$L^{p,q}(\mathbb{R}^n)$. All these characterizations are new even for the
classical isotropic Hardy-Lorentz spaces on $\mathbb{R}^n$. Moreover, the range
of $\lambda$ in the $g_\lambda^*$-function characterization of
$H^{p,q}_A(\mathbb{R}^n)$ coincides with the best known one in the classical
Hardy space $H^p(\mathbb{R}^n)$ or in the anisotropic Hardy space
$H^p_A(\mathbb{R}^n)$.",1601.05242v2
2016-01-25,Lorentz violation naturalness revisited,"We revisit here the naturalness problem of Lorentz invariance violations on a
simple toy model of a scalar field coupled to a fermion field via a Yukawa
interaction. We first review some well-known results concerning the low-energy
percolation of Lorentz violation from high energies, presenting some details of
the analysis not explicitly discussed in the literature and discussing some
previously unnoticed subtleties. We then show how a separation between the
scale of validity of the effective field theory and that one of Lorentz
invariance violations can hinder this low-energy percolation. While such
protection mechanism was previously considered in the literature, we provide
here a simple illustration of how it works and of its general features.
Finally, we consider a case in which dissipation is present, showing that the
dissipative behaviour does not percolate generically to lower mass dimension
operators albeit dispersion does. Moreover, we show that a scale separation can
protect from unsuppressed low-energy percolation also in this case.",1601.06700v2
2016-02-01,Tests of Lorentz and CPT symmetry with hadrons and nuclei,"We explore the breaking of Lorentz and CPT invariance in strong interactions
at low energy in the framework of chiral perturbation theory. Starting from the
set of Lorentz-violating operators of mass-dimension five with quark and gluon
fields, we construct the effective chiral Lagrangian with hadronic and
electromagnetic interactions induced by these operators. We develop the
power-counting scheme and discuss loop diagrams and the one-pion-exchange
nucleon-nucleon potential. The effective chiral Lagrangian is the basis for
calculations of low-energy observables with hadronic degrees of freedom. As
examples, we consider clock-comparison experiments with nuclei and
spin-precession experiments with nucleons in storage rings. We derive strict
limits on the dimension-five tensors that quantify Lorentz and CPT violation.",1602.00496v2
2016-02-06,On Unification of Gravity and Gauge Interactions,"Considering a higher dimensional Lorentz group as the tangent symmetry, we
unify gravity and gauge interactions in a natural way. The spin connection of
the gauged Lorentz group is then responsible for both gravity and gauge fields,
and the action for the gauged fields becomes part of the spin curvature
squared. The realistic group which unifies all known particles and interactions
is the $SO(1,13)$ Lorentz group whose gauge part leads to $SO(10)$ grand
unified theory and contains double the number of required fermions in the
fundamental spinor representation. Mirror fermions could acquire mass utilizing
a mechanism employed for topological superconductors. Family unification could
be achieved by considering the $SO(1,21)$ Lorentz group.",1602.02295v3
2016-03-04,Lifshitz-scaling to Lorentz-violating high derivative operator and gamma-ray busts,"In this work we have used a Ho\v{r}ava-Lifshitz scaling to rewrite a
Lorentz-violating higher-order derivative electrodynamics controlled by a
background four-vector $n_{\mu}$. The photon propagator was obtained and we
have analyzed the dispersion relation and the observational results of
gamma-ray burst (GRB) experiments were used. The limits of the critical
exponent were discussed in the light of the GRB data and the physical
implications were compared with the current GRB-Lorentz-invariance-violation
literature. We show that the bound for the Lorentz-violating coupling for
dimension-six operators, obtained from a Ho\v{r}ava-Lifshitz scaling, is eight
orders of magnitude better than the result found without considering a
Ho\v{r}ava-Lifshitz scaling, also this bound is nearby one, which is expected
to be relevant phenomenologically.",1603.01558v2
2016-03-06,Complete Lorentz transformation of a charge-current density,"It is generally assumed in the literature that a Lorentz transformation on a
neutral current loop results in a moving current loop with a nonvanishing
charge distribution and an electric dipole moment. We show in this paper that
this is not, in fact, correct. The derivation that leads to the charge
distribution was based on an incomplete Lorentz transformation, which
transforms the charge-current four-vector $j^\mu=[\rho({\bf r},t),{\bf
j(r},t)]$, but not the space-time four-vector $x^\mu=(t,{\bf r})$.
  We show that completing the Lorentz transformation by using the variable $t'$
in the moving frame, rather than keeping the rest frame time variable $t$,
results in there being no induced charge density and no resulting electric
dipole moment.",1603.02912v6
2016-03-24,Fermionic Lorentz violation and its implications for interferometric gravitational-wave detection,"The recent direct detection of gravitational waves reported by Advanced LIGO
has inspired the current article. In this context, a particular
Lorentz-violating framework for classical, massive particles is the focus. The
latter is characterized by a preferred direction in spacetime comprised of
CPT-odd components with mass dimension 1. Curvature effects in spacetime, which
are caused by a propagating gravitational wave, are assumed to deform the
otherwise constant background field. In accordance with spontaneous Lorentz
violation, a particular choice for the vector field is taken, which was
proposed elsewhere. The geodesic equations for a particle that is subject to
this type of Lorentz violation are obtained. Subsequently, their numerical
solutions are computed and discussed. The particular model considered leads to
changes in the particle trajectory whose impact on interferometric
gravitational-wave experiments such as LIGO will be studied.",1603.07452v2
2016-04-08,Photon gravitational defection in Lorentz violating scenarios,"The effect of Lorentz symmetry violation in the phenomenon of photon
gravitational bending, is investigated. Using a semiclassical approach, where
the photon is described by the Carrol-Field-Jackiw (CFJ) electrodynamics which
is responsible for implementing the Lorentz symmetry violation, the
gravitational deflection angle related to the CFJ photon is computed. As
expected, this bending angle experiences a deviation from the usual Einstein
result and the latter is recovered in the appropriate limit. A comparison
between the theoretical prediction and the experimental results allows to
conclude that no trace of Lorentz symmetry breaking is found provided the
components of the background vector field are $\lesssim 10^{-8}$ eV.",1604.05153v2
2016-06-03,New effects in the interaction between electromagnetic sources mediated by nonminimal Lorentz violating interactions,"This paper is dedicated to the study of interactions between external sources
for the electromagnetic field in a Lorentz symmetry breaking scenario. We focus
on a particular higher derivative, Lorentz violating interaction that arises
from a specific model that was argued to lead to interesting effects in the low
energy phenomenology of light pseudoscalars interacting with photons. The kind
of higher derivative Lorentz violating interaction we discuss do not appear in
the well known Standard Model Extension, therefore they are called nonminimal.
They are usually expected to be relevant only at very high energies, but we
argue they might also induce relevant effects in low energy phenomena. Special
attention is given for phenomena that have no counterpart in Maxwell theory.",1606.00940v2
2016-07-04,Fine-tuning problems in quantum field theory and Lorentz invariance: A scalar-fermion model with a physical momentum cutoff,"We study the consistency of having Lorentz invariance as a low energy
approximation within the quantum field theory framework. A model with a scalar
and a fermion field is used to show how a Lorentz invariance violating high
momentum scale, a physical cutoff rendering the quantum field theory finite,
can be made compatible with a suppression of Lorentz invariance violations at
low momenta. The fine tuning required to get this suppression and to have a
light scalar particle in the spectrum is determined at one loop.",1607.00744v2
2016-07-07,Changes in extensive air showers from isotropic Lorentz violation in the photon sector,"We consider a theory with isotropic nonbirefringent Lorentz violation in the
photon sector and explore the effects on the development of the electromagnetic
component of extensive air showers in the Earth atmosphere. Specifically, we
consider the case of a ""fast"" photon with a phase velocity larger than the
maximum attainable velocity of a massive Dirac fermion (this case corresponds
to a negative Lorentz-violating parameter $\kappa$ in the action). Shower
photons with above-threshold energies decay promptly into electron-positron
pairs, instead of decaying by the conventional production of electron-positron
pairs in the background fields of atomic nuclei. This rapid production of
charged leptons accelerates the shower development, decreasing the atmospheric
depth of the shower maximum ($X_\text{max}$) by an amount which could be
measured by cosmic-ray observatories. Precise measurements of $X_\text{max}$
could then improve existing limits on the negative Lorentz-violating parameter
$\kappa$ by several orders of magnitude.",1607.02099v4
2016-07-20,Combined search for Lorentz violation in short-range gravity,"Short-range experiments testing the gravitational inverse-square law at the
submillimeter scale offer uniquely sensitive probes of Lorentz invariance. A
combined analysis of results from the short-range gravity experiments
HUST-2015, HUST-2011, IU-2012, and IU-2002 permits the first independent
measurements of the 14 nonrelativistic coefficients for Lorentz violation in
the pure-gravity sector at the level of $10^{-9}$ m$^2$, improving by an order
of magnitude the sensitivity to numerous types of Lorentz violation involving
quadratic curvature derivatives and curvature couplings.",1607.06095v1
2016-07-25,Acoustic tests of Lorentz symmetry using Bulk Acoustic Wave quartz oscillators,"A new method of probing Lorentz invariance in the neutron sector is
described. The method is baed on stable quartz bulk acoustic wave oscillators
compared on a rotating table. Due to Lorentz-invariance violation, the
resonance frequencies of acoustic wave resonators depend on the direction in
space via a corresponding dependence of masses of the constituent elements of
solids. This dependence is measured via observation of oscillator phase noise
built around such devices. The first such experiment now shows sensitivity to
violation down to the limit $\tilde{c}^n_Q=(-1.8\pm2.2)\times 10^{-14}$ GeV.
Methods to improve the sensitivity are described together with some other
applications of the technology in tests of fundamental physics.",1607.07179v2
2016-09-18,Non-orthogonality and $κ$-dependence eccentricity of polarized electromagnetic waves in CPT-even Lorentz violation,"We discuss the modified Maxwell action of a $K_{F}$-type Lorentz symmetry
breaking theory and present a solution of Maxwell equations derived in the
cases of linear and elliptically polarized electromagnetic waves in the vacuum
of CPT-even Lorentz violation. We show in this case the Lorentz violation has
the effect of changing the amplitude of one component of the magnetic field,
while leaving the electric field unchanged, leading to non-orthogonal
propagation of eletromagnetic fields and dependence of the eccentricity on
$\kappa$-term. Further, we exhibit numerically the consequences of this effect
in the cases of linear and elliptical polarization, in particular, the regimes
of non-orthogonality of the electromagnetic wave fields and the eccentricity of
the elliptical polarization of the magnetic field with dependence on the
$\kappa$-term.",1609.05889v3
2016-09-30,Restrictions from Lorentz invariance violation on cosmic ray propagation,"Lorentz Invariance Violation introduced as a generic modification to particle
dispersion relations is used to study high energy cosmic ray attenuation
processes. It is shown to reproduce the same physical effects for vacuum
Cherenkov radiation, as in some particular models with spontaneous breaking of
Lorentz symmetry. This approximation is also implemented for the study of
photon decay in vacuum, where stringent limits to the violation scale are
derived from the direct observation of very high energy cosmic ray photon
events on gamma telescopes. Photo production processes by cosmic ray primaries
on photon background are also addressed, to show that Lorentz violation may
turn off this attenuation process at energies above a well defined secondary
threshold.",1610.00047v3
2016-10-02,Revisiting EPRL: All Finite-Dimensional Solutions by Naimark's Fundamental Theorem,"In this paper we research all possible finite-dimensional representations and
corresponding values of the Barbero-Immirzi parameter contained in EPRL
simplicity constraints by using Naimark's fundamental theorem of the Lorentz
group representation theory. It turns out that for each non-zero pure imaginary
with rational modulus value of the Barbero-Immirzi parameter $\gamma = i
\frac{p}{q}, p, q \in Z, p, q \ne 0$, there is a solution of the simplicity
constraints, such that the corresponding Lorentz representation is finite
dimensional. The converse is also true - for each finite-dimensional Lorentz
representation solution of the simplicity constraints $(n, \rho)$, the
associated Barbero-Immirzi parameter is non-zero pure imaginary with rational
modulus, $\gamma = i \frac{p}{q}, p, q \in Z, p, q \ne 0$. We solve the
simplicity constraints with respect to the Barbero-Immirzi parameter and then
use Naimark's fundamental theorem of the Lorentz group representations to find
all finite-dimensional representations contained in the solutions.",1610.00356v4
2016-10-11,Lorentz-violating neutral-pion decays in isotropic modified Maxwell theory,"We consider an extension of the Standard Model with isotropic nonbirefringent
Lorentz violation in the photon sector and restrict the discussion to the case
of a ""fast"" photon with a phase velocity larger than the maximum attainable
velocity of the quarks and leptons. With our conventions, this case corresponds
to a negative Lorentz-violating parameter $\kappa$ in the action. The decay
rate of a neutral pion into two nonstandard photons is calculated as a function
of the 3-momentum of the initial pion and the negative Lorentz-violating
parameter $\kappa$ of the final photons.",1610.03315v4
2017-02-03,Angular Momentum Conservation Law in Light-Front Quantum Field Theory,"We prove the Lorentz invariance of the angular momentum conservation law and
the helicity sum rule for relativistic composite systems in the light-front
formulation. We explicitly show that $j^3$, the $z$-component of the angular
momentum remains unchanged under Lorentz transformations generated by the
light-front kinematical boost operators. The invariance of $j^3$ under Lorentz
transformations is a feature unique to the front form. Applying the Lorentz
invariance of the angular quantum number in the front form, we obtain a
selection rule for the orbital angular momentum which can be used to eliminate
certain interaction vertices in QED and QCD. We also generalize the selection
rule to any renormalizable theory and show that there exists an upper bound on
the change of orbital angular momentum in scattering processes at any fixed
order in perturbation theory.",1702.01127v2
2017-03-08,Remote Sub-Wavelength Focusing of Ultrasonically Activated Lorentz Current,"We propose the use of a combination of ultrasonic and magnetic fields in
conductive media for the creation of RF electrical current via the Lorentz
force, in order to achieve current generation with extreme sub-wavelength
resolution at large depth. We demonstrate the modeling, generation, and
measurement of Lorentz current in conductive solution, and show that this
current can be localized at a distance of 13 $cm$ from the ultrasonic source to
a region about three orders of magnitude smaller than the corresponding
wavelength of electromagnetic waves at the same operation frequency. Our
results exhibit greater depth, tighter localization, and closer agreement with
prediction than previous work on the measurement of Lorentz current in a
solution of homogeneous conductivity. The proposed method of RF current
excitation overcomes the trade-off between focusing and propagation that is
fundamental in the use of RF electromagnetic excitation alone, and has the
potential to improve localization and depth of operation for RF current-based
biomedical applications.",1703.02732v1
2017-03-10,f(R) gravity with torsion and Lorentz violation,"The Lounesto spinor classification is an important tool in fundamental
physics, because it makes explicit the pleiade of spinors types, beyond the
used in quantum field theory (QFT). In this work, we show how the
classification emerges in two topics: first we show that the bilinear
covariants arise naturally in the equation of motion for a fermionic field in a
Riemann-Cartan background (with gravitational dynamics f(R)) and we identify a
singular spinor field (a flag-dipole one) as a solution of the presented model.
This is the first solution flag-dipole founded in the literature. We
investigated the behavior of the bilinear covariants in the context of the
called standard model extension of Colladay and Kostelecky and we present
examples of transformations that violate the Lorentz symmetry, providing an
extension of spinors classification, according to bilinear covariants, to
scenarios with broken Lorentz symmetry. Finally, we proved that singular
spinors of type flagpole are less susceptible to effects of Lorentz violation.",1703.03682v1
2018-02-02,Asymptotic single-particle states and exact Lorentz-violating all-loop quantum corrections for scalar field theory,"We perform the all-loop renormalization of the O($N$) $\lambda\phi^{4}$
scalar field theory with Lorentz violation which is exact in the
Lorentz-violating $K_{\mu\nu}$ coefficients. This task is fulfilled
analytically firstly explicitly at next-to-leading order and later at all loop
levels through an induction process based on a general theorem emerging from
the exact approach. We show that the exact results reduce to the approximated
ones, previously obtained, in the appropriated limit and comment on their
implications. The current exact calculation involving such a symmetry breaking
mechanism in the referred theory is the first one in literature for our
knowledge. At the end, we analyze the effect of Lorentz violation on the
asymptotic single-particle states.",1802.00823v1
2018-02-12,Lorentz-boost eigenmodes,"Plane waves and cylindrical or spherical vortex modes are important sets of
solutions of quantum and classical wave equations. These are eigenmodes of the
energy-momentum and angular-momentum operators, i.e., generators of spacetime
translations and spatial rotations, respectively. Here we describe another set
of wave modes: eigenmodes of the ""boost momentum"" operator, i.e., a generator
of Lorentz boosts (spatio-temporal rotations). Akin to the angular momentum,
only one (say, z) component of the boost momentum can have a well-defined
quantum number. The boost eigenmodes exhibit invariance with respect to the
Lorentz transformations along the z-axis, leading to scale-invariant wave forms
and step-like singularities moving with the speed of light. We describe basic
properties of the Lorentz-boost eigenmodes and argue that these can serve as a
convenient basis for problems involving causal propagation of signals.",1802.03940v2
2018-04-12,The effect of Lorentz-like force on collective flows of K$^{+}$ in Au+Au collisions at 1.5 GeV/nucleon}{The effect of Lorentz-like force on collective flows of $K^{+}$ in Au+Au collisions at 1.5 GeV/nucleon,"Producing kaon mesons in heavy-ion collisions at beam energies below their
threshold energy is an important way to investigate the properties of dense
nuclear matter. In this study, based on the newly updated version of the
ultrarelativistic quantum molecular dynamics model, we introduce the
kaon-nucleon (KN) potential, including both the scalar and vector (also dubbed
Lorentz-like) aspects. We revisit the influence of the KN potential on the
collective flow of K$^{+}$ mesons produced in Au+Au collisions at $E_{lab}$ =
1.5 GeV/nucleon and find that the contribution of the newly included
Lorentz-like force is very important, particulary for describing the directed
flow of K$^{+}$. Finally, the corresponding KaoS data of both directed and
elliptic flows can be simultaneously reproduced well.",1804.04294v1
2018-04-17,Exact Lorentz-violating all-loop ultraviolet divergences in scalar field theories,"In this work we evaluate analytically the ultraviolet divergences of
Lorentz-violating massive O($N$) $\lambda\phi^{4}$ scalar field theories, which
are exact in the Lorentz-violating mechanism, firstly explicitly at
next-to-leading order and latter at any loop level through an induction
procedure based on a theorem following from the exact approach, for computing
the corresponding critical exponents. For attaining that goal, we employ three
different and independent field-theoretic renormalization group methods. The
results found for the critical exponents show that they are identical in the
three distinct methods and equal to their Lorentz invariant counterparts.
Furthermore, we show that the results obtained here, based on the single
concept of loop order of the referred terms of the corresponding
$\beta$-function and anomalous dimensions, reduce to the ones obtained through
the earlier non-exact approach based on a joint redefinition of the field and
coupling constant of the theory, in the appropriate limit.",1804.06503v2
2018-11-06,The Lorentz sphere visualized,"From the inception of Nuclear Magnetic Resonance as a spectroscopic
technique, the local origin of chemical shifts has been a topic of discussion.
A useful concept employed to describe it has been that of the ""Lorentz sphere"",
the approximately spherical volume surrounding a given nucleus in which the
electronic currents contribute significantly to the chemical shift, whereas the
outside can be considered as an uniformly magnetised ""bulk"". In this paper we
use the output of the plane wave DFT code CASTEP to get a quantitative estimate
of the Lorentz sphere in periodic systems. We outline a mathematical
description of a radial buildup function for the magnetic shielding starting
from the electronic currents and the simple assumption of periodicity. We
provide an approximate upper bound for the Lorentz sphere's size in any
crystal, then compute buildup functions for a number of sites in two molecular
crystals, showing how various chemical features such as hydrogen bonds
influence to convergence to the final shielding value.",1811.02347v3
2018-11-06,Optimal embeddings into Lorentz spaces for some vector differential operators via Gagliardo's lemma,"We prove a family of Sobolev inequalities of the form $$
  \Vert u \Vert_{L^{\frac{n}{n-1}, 1} (\mathbb{R}^n,V)}
  \le
  \Vert A (D) u \Vert_{L^1 (\mathbb{R}^n,E)} $$ where $A (D) : C^\infty_c
(\mathbb{R}^n, V) \to C^\infty_c (\mathbb{R}^n, E)$ is a vector first-order
homogeneous linear differential operator with constant coefficients, $u$ is a
vector field on $\mathbb{R}^n$ and $L^{\frac{n}{n - 1}, 1} (\mathbb{R}^{n})$ is
a Lorentz space. These new inequalities imply in particular the extension of
the classical Gagliardo-Nirenberg inequality to Lorentz spaces originally due
to Alvino and a sharpening of an inequality in terms of the deformation
operator by Strauss (Korn-Sobolev inequality) on the Lorentz scale. The proof
relies on a nonorthogonal application of the Loomis--Whitney inequality and
Gagliardo's lemma.",1811.02691v1
2018-11-12,Planewave Response of a Simple Lorentz-Nonreciprocal Medium with Magnetoelectric Gyrotropy,"The simple Lorentz-nonreciprocal medium described by the constitutive
relations ${\bf D}=\epsilon_o\epsilon_r{\bf E]-{\bf\Gamma}\times{\bf H}$ and
${\bf B}=\mu_o\mu_r{\bf H]-{\bf\Gamma}\times{\bf E}$ is inspired by a specific
spacetime metric, $\bf\Gamma$ being the magnetoelectric-gyrotopy vector. Field
representations in this medium can be obtained from those for the isotropic
dielectric-magnetic medium. When a plane wave is incident on a half space
occupied by the Lorentz-nonreciprocal medium with magnetoelectric gyrotopy,
theory shows that the transverse component of the magnetoelectric-gyrotopy
vector is responsible for a rotation about the normal axis; furthermore,
left/right reflection asymmetry is exhibited. Additionally, left/right
transmission asymmetry is exhibited by a planar slab composed of the
Lorentz-nonreciprocal medium with magnetoelectric gyrotopy. The left/right
asymmetries are of interest for one-way devices.",1811.05034v1
2018-11-16,Normal and Anomalous Diffusion in Soft Lorentz Gases,"Motivated by electronic transport in graphene-like structures, we study the
diffusion of a classical point particle in Fermi potentials situated on a
triangular lattice. We call this system a soft Lorentz gas, as the hard disks
in the conventional periodic Lorentz gas are replaced by soft repulsive
scatterers. A thorough computational analysis yields both normal and anomalous
(super) diffusion with an extreme sensitivity on model parameters. This is due
to an intricate interplay between trapped and ballistic periodic orbits, whose
existence is characterized by tongue-like structures in parameter space. These
results hold even for small softness showing that diffusion in the paradigmatic
hard Lorentz gas is not robust for realistic potentials, where we find an
entirely different type of diffusion.",1811.06976v2
2018-11-28,Energy-dependent diffusion in a soft periodic Lorentz gas,"The periodic Lorentz gas is a paradigmatic model to examine how macroscopic
transport emerges from microscopic chaos. It consists of a triangular lattice
of circular hard scatterers with a moving point particle. Recently this system
became relevant as a model for electronic transport in low-dimensional
nanosystems such as molecular graphene. However, to more realistically mimic
such dynamics, the hard Lorentz gas scatterers should be replaced by soft
potentials. Here we study diffusion in a soft Lorentz gas with Fermi potentials
under variation of the total energy of the moving particle. Our goal is to
understand the diffusion coefficient as a function of the energy. In our
numerical simulations we identify three different dynamical regimes: (i) the
onset of diffusion at small energies; (ii) a transition where for the first
time a particle reaches the top of the potential, characterized by the
diffusion coefficient abruptly dropping to zero; and (iii) diffusion at high
energies, where the diffusion coefficient increases according to a power law in
the energy. All these different regimes are understood analytically in terms of
simple random walk approximations.",1811.11661v1
2019-05-02,On a Gambini-Pullin-inspired Maxwell electrodynamics with Lorentz-violating dimension-$5$ operators,"We explore the properties of a new Maxwell electrodynamics coupled to a
Lorentz-violating background through the presence of higher-derivative terms.
Physical implications of this alternative effective theory modified by
Lorentz-violating operators of mass dimension-$5$ are considered, such as
modified dispersion relations which exhibit the vacuum birefringence
phenomenon. Subsequently, we analyze the energy-momentum tensor in the case we
reproduce the Gambini-Pullin electrodynamics. We explicitly show that for a
background time-like four-vector, $n^{\mu}$, the equations of motion indeed
reproduce those encountered by Gambini and Pullin in the framework of loop
quantum gravity . Finally, extended expressions for Maxwell-type equations are
written down in the case the external Lorentz-violating four-vector is
space-like.",1905.00779v1
2019-05-13,Fuzzy Classical Dynamics as a Paradigm for Emerging Lorentz Geometries,"We show that the classical equations of motion for a particle on three
dimensional fuzzy space and on the fuzzy sphere are underpinned by a natural
Lorentz geometry. From this geometric perspective, the equations of motion
generally correspond to forced geodesic motion, but for an appropriate choice
of noncommutative dynamics, the force is purely noncommutative in origin and
the underpinning Lorentz geometry some standard space-time with, in general,
non-commutatuve corrections to the metric. For these choices of the
noncommutative dynamics the commutative limit therefore corresponds to geodesic
motion on this standard space-time. We identify these Lorentz geometries to be
a Minkowski metric on $\mathbb{R}^4$ and $\mathbb{R} \times S ^2$ in the cases
of a free particle on three dimensional fuzzy space ($\mathbb{R}^3_\star$) and
the fuzzy sphere ($S^2_\star$), respectively. We also demonstrate the
equivalence of the on-shell dynamics of $S^2_\star$ and a relativistic charged
particle on the commutative sphere coupled to the background magnetic field of
a Dirac monopole.",1905.05018v1
2019-05-21,Pulsar tests of the gravitational Lorentz violation,"Pulsars are precision celestial clocks. When being put in a binary, the
ticking conveys the secret of underlying spacetime geometrodynamics. We use
pulsars to test if the gravitational interaction possesses a tiny deviation
from Einstein's General Relativity (GR). In the framework of Standard-Model
Extension (SME), we systematically search for Lorentz-violating operators
cataloged by (a) the minimal couplings of mass dimension 4, (b) the CPT
symmetry of mass dimension 5, and (c) the gravitational weak equivalence
principle (GWEP) of mass dimension 8. No deviation from GR was found yet.",1905.08405v1
2010-05-10,Faster Than Light?,"It is argued that special relativity remains a viable physical theory even
when there is permitted signals traveling faster than light.",1005.1614v1
2013-08-12,Contributions to Pion Decay from Lorentz Violation in the Weak Sector,"Lorentz violation in the weak sector would affect the beta-decay lifetimes of
pions. The decay amplitude may be rendered anisotropic, but only an isotropic
violation of boost invariance can affect the net lifetime in the center of mass
frame. However, since the rest frames of the pions that produce the NuMI
neutrino beam at Fermilab vary with the rotation of the Earth, it is possible
to constrain anisotropic Lorentz violation using prior analyses of sidereal
variations in the event rate at the MINOS near detector. The resulting bounds
on weak-sector Lorentz violation are at the 10^(-4) level, a substantial
improvement over previous results. The highly relativistic character of the
pions involved is responsible for the improvement.",1308.2602v1
2013-08-21,A Study of Dynamic Lorentz Force Detuning of 650 MHz βg= 0.9 Superconducting Radiofrequency Cavity,"The small bandwidth of superconducting cavities makes the study of dynamic
Lorentz force detuning and its compensation indispensable in case of pulsed
mode operation of high gradient accelerators. In this paper, we present the
study of this detuning and also propose an optimized design for five cell 650
MHz {\beta}g= 0.9 elliptic superconducting cavities, which will be used in the
high energy section of the 1 GeV H- linear accelerator for the proposed Indian
Spallation Neutron Source project, by suitably inserting the inter-cell
stiffeners. The paper presents a sequential design methodology which starts
with study of static Lorentz force detuning and tunability; and progresses to
find out the structural modes and related dynamic detuning values by performing
transient structural dynamics calculations. The developed methodology is
general in nature and can be used for a three dimensional model of any
geometry. The work will be useful for optimizing the design against dynamic
Lorentz force detuning of superconducting radiofrequency cavities of any shape.",1308.4532v2
2013-08-22,Fermions with Lorentz-violating operators of arbitrary dimension,"The theoretical description of fermions in the presence of Lorentz and CPT
violation is developed. We classify all Lorentz- and CPT-violating and
invariant terms in the quadratic Lagrange density for a Dirac fermion,
including operators of arbitrary mass dimension. The exact dispersion relation
is obtained in closed and compact form, and projection operators for the
spinors are derived. The Pauli hamiltonians for particles and antiparticles are
extracted, and observable combinations of operators are identified. We
characterize and enumerate the coefficients for Lorentz violation for any
operator mass dimension via a decomposition using spin-weighted spherical
harmonics. The restriction of the general theory to various special cases is
presented, including isotropic models, the nonrelativistic and
ultrarelativistic limits, and the minimal Standard-Model Extension. Expressions
are derived in several limits for the fermion dispersion relation, the
associated fermion group velocity, and the fermion spin-precession frequency.
We connect the analysis to some other formalisms and use the results to extract
constraints from astrophysical observations on isotropic ultrarelativistic
spherical coefficients for Lorentz violation.",1308.4973v1
2013-08-29,Limits on Lorentz violation in neutral-Kaon decay,"The KLOE collaboration recently reported bounds on the directional dependence
of the lifetime of the short-lived neutral kaon K_S with respect to the cosmic
microwave background dipole anisotropy. We interpret their results in a general
framework developed to probe Lorentz violation in the weak interaction. In this
approach a Lorentz-violating tensor \chi_{\mu\nu} is added to the standard
propagator of the W boson. We derive the K_S decay rate in a naive tree-level
model and calculate the asymmetry for the lifetime. By using the KLOE data the
real vector part of \chi_{\mu\nu} is found to be smaller than 10^-2. We briefly
discuss the theoretical challenges concerning nonleptonic decays.",1308.6468v1
2014-03-11,Lorentz Violation in Fermion-Antifermion Decays of Spinless Particles,"If Lorentz and CPT violation exist, they could affect the decays of scalar
and pseudoscalar particles. For a decay into a fermion and an antifermion (not
necessarily of the same mass), both the total decay rate and the outgoing
particle distribution may be modified, through interference between the
conventional decay mechanism and a separate Lorentz-violating mechanism. The
modifications are sensitive to forms of Lorentz violation that are otherwise
rather difficult to study, since at tree level they do not affect particle
propagation, but only interaction vertices. Using existing experimental data on
charged pion decay, it is possible to constrain three parameters in the
modified pion-muon-neutrino coupling at better than the $10^{-9}$ level; these
are the first bounds on these quantities.",1403.2751v1
2014-03-13,Lorentz violation and topological defects,"If Lorentz symmetry is broken, it must have occurred dynamically, via a
vector or tensor field whose potential energy forces it to take on a non-zero
background expectation value ""in vacuum"". If the set of minima of this
potential (the vacuum manifold) has a non-trivial topology, then there can
arise topological defects: stable solutions in which the field approaches
different potential minima as we go to infinity in different directions. I
discuss the current status of research into these topological defects in the
context of Lorentz symmetry breaking, including recent results concerning the
birefringent light-bending of monopole solutions, and the search for models
supporting cosmic-string and domain-wall defects.",1403.3302v1
2014-03-30,What Do We Know About Lorentz Invariance?,"The realization that Planck-scale physics can be tested with existing
technology through the search for spacetime-symmetry violation brought about
the development of a comprehensive framework, known as the gravitational
Standard-Model Extension (SME), for studying deviations from exact Lorentz and
CPT symmetry in nature. The development of this framework and its motivation
led to an explosion of new tests of Lorentz symmetry over the past decade and
to considerable theoretical interest in the subject. This work reviews the key
concepts associated with Lorentz and CPT symmetry, the structure of the SME
framework, and some recent experimental and theoretical results.",1403.7785v1
2016-11-01,Generalizing the Lorentz transformations,"In this paper we develop a framework allowing a natural extension of the
Lorentz transformations. To begin, we show that by expanding conventional
four-dimensional spacetime to eight-dimensions that a natural generalization is
indeed obtained. We then find with these generalized coordinate transformations
acting on Maxwell's equations that the electromagnetic field transformations
are nevertheless unchanged. We find further, that if we assume the absence of
magnetic monopoles, in accordance with Maxwell's theory, our generalized
transformations are then restricted to be the conventional ones. While the
conventional Lorentz transformations are indeed recovered from our framework,
we nevertheless provide a new perspective into why the Lorentz transformations
are constrained to be the conventional ones. Also, this generalized framework
may assist in explaining several unresolved questions in electromagnetism as
well as to be able to describe quasi magnetic monopoles found in spin-ice
systems.",1611.02564v1
2017-01-19,Improved Tests of Lorentz Invariance in the Matter Sector using Atomic Clocks,"For the purpose of searching for Lorentz-invariance violation in the minimal
Standard-Model Extension, we perfom a reanalysis of data obtained from the
$^{133}\text{Cs}$ fountain clock operating at SYRTE. The previous study led to
new limits on eight components of the $\tilde{c}_{\mu\nu}$ tensor, which
quantifies the anisotropy of the proton kinetic energy. We recently derived an
advanced model for the frequency shift of hyperfine Zeeman transition due to
Lorentz violation and became able to constrain the ninth component, the
isotropic coefficient $\tilde{c}_{TT}$, which is the least well-constrained
coefficient of $\tilde{c}_{\mu\nu}$. This model is based on a second-order
boost Lorentz transformation from the laboratory frame to the Sun-centered
frame, and it gives rise to an improvement of five orders of magnitude on
$\tilde{c}_{TT}$ compared to the state of the art.",1701.06902v1
2017-04-19,Refractive index of dense materials,"We show that applying the Lorentz-Lorenz transformation to the refractive
index of metals, semiconductors and insulators allows for a less empirical
modeling of this refractive index.",1704.05718v1
2011-11-18,Geometrical Models of the Locally Anisotropic Space-Time,"Along with the construction of non-Lorentz-invariant effective field
theories, recent studies which are based on geometric models of Finsler
space-time become more and more popular. In this respect, the Finslerian
approach to the problem of Lorentz symmetry violation is characterized by the
fact that the violation of Lorentz symmetry is not accompanied by a violation
of relativistic symmetry. That means, in particular, that preservation of
relativistic symmetry can be considered as a rigorous criterion of the
viability for any non-Lorentz-invariant effective field theory. Although this
paper has a review character, it contains (with few exceptions) only those
results on Finsler extensions of relativity theory, that were obtained by the
authors.",1111.4346v1
2011-11-25,Restoration of Lorentz Symmetry for Lifshitz-Type Scalar Theory,"The purpose of this paper is to present our study on the restoration of the
Lorentz symmetry for a Lifshitz-type scalar theory in the infrared region by
using nonperturbative methods. We apply the Wegner-Houghton equation, which is
one of the exact renormalization group equations, to the Lifshitz-type theory.
Analyzing the equation for a z=2, d=3+1 Lifshitz-type scalar model, and using
some variable transformations, we found that broken symmetry terms vanish in
the infrared region. This shows that the Lifshitz-type scalar model dynamically
restores the Lorentz symmetry at low energy. Our result provides a definition
of ultraviolet complete renormalizable scalar field theories. These theories
can have nontrivial interaction terms of \phi^{n} (n=4, 6, 8, 10) even when the
Lorentz symmetry is restored at low energy.",1111.6075v3
2013-09-16,A CPT-even Lorentz-violating nonminimal coupling between fermions and photons,"We propose a CPT-even and Lorentz-violating dimension-five nonminimal
coupling between fermionic and gauge fields, involving the CPT-even and
Lorentz-violating gauge tensor of the Standard-Model Extension. This nonminimal
coupling modifies the nonrelativistic regime of Dirac particles, inducing new
effects such as an electric-Zeeman-like spectrum splitting and an
anomalous-like contribution to the electron magnetic moment. These new effects
allow to constrain the magnitude of this nonminimal coupling in 1 part in
$10^{16}.$",1309.3928v1
2013-09-27,Planck's uncertainty principle and the saturation of Lorentz boosts by Planckian black holes,"A basic inconsistency arises when the Theory of Special Relativity meets with
quantum phenomena at the Planck scale. Specifically, the Planck length is
Lorentz invariant and should not be affected by a Lorentz boost. We argue that
Planckian relativity must necessarily involve the effect of black hole
formation. Recent proposals for resolving the noted inconsistency seem
unsatisfactory in that they ignore the crucial role of gravity in the
saturation of Lorentz boosts. Furthermore, an invariant length at he Planck
scale amounts to a universal quantum of resolution in the fabric of spacetime.
We argue, therefore, that the universal Planck length requires an extension of
the Uncertainty Principle as well. Thus, the noted inconsistency lies at the
core of Quantum Gravity. In this essay we reflect on a possible resolution of
these outstanding problems.",1309.7186v1
2013-09-29,"Polarization properties of photospheric emission from relativistic, collimated outflows","We consider the polarization properties of photospheric emission originating
in jets consisting of a highly relativistic core of opening angle theta_j and
Lorentz factor Gamma_0, and a surrounding shear layer where the Lorentz factor
is decreasing as a power law of index p with angle from the jet axis. We find
significant degrees of linear polarization for observers located at viewing
angles theta_v \gtrsim theta_j. In particular, the polarization degree of
emission from narrow jets (theta_j \approx 1/Gamma_0) with steep Lorentz factor
gradients (p \gtrsim 4) reaches \sim 40%. The angle of polarization may shift
by pi/2 for time-variable jets. The spectrum below the thermal peak of the
polarized emission appears non-thermal due to aberration of light, without the
need for additional radiative processes or energy dissipation. Furthermore,
above the thermal peak a power law of photons forms due to Comptonization of
photons that repeatedly scatter between regions of different Lorentz factor
before escaping. We show that polarization degrees of a few tens of percent and
broken power law spectra are natural in the context of photospheric emission
from structured jets. Applying the model to gamma-ray bursts, we discuss
expected correlations between the spectral shape and the polarization degree of
the prompt emission.",1309.7652v1
2014-05-20,"How General Relativity and Lorentz Covariance Arise from the Spatially Covariant Effective Field Theory of the Transverse, Traceless Graviton","Traditional derivations of general relativity from the graviton degrees of
freedom assume space-time Lorentz covariance as an axiom. In this essay, we
survey recent evidence that general relativity is the unique
spatially-covariant effective field theory of the transverse, traceless
graviton degrees of freedom. The Lorentz covariance of general relativity,
having not been assumed in our analysis, is thus plausibly interpreted as an
accidental or emergent symmetry of the gravitational sector. From this point of
view, Lorentz covariance is a necessary feature of low-energy graviton
dynamics, not a property of space-time. This result has revolutionary
implications for fundamental physics.",1405.5219v1
2014-05-28,The CGEM Lorentz Force Data from HMI Vector Magnetograms,"We describe a new data product from the CGEM (Coronal Global Evolutionary
Model) collaboration that estimates the Lorentz force in active regions (ARs)
based on HMI vector magnetogram patches. Following Fisher et al. (2012), we
compute three components of the integrated Lorentz force over the outer solar
atmosphere every 12 minutes throughout an AR's disk passage. These estimates,
differenced during solar eruptive events, can provide valuable diagnostics on
dynamic processes. We describe the pipeline modules, provide data retrieval
examples, and document some systematic uncertainties that users should be aware
of. Finally we document the formal uncertainty propagation procedures.",1405.7353v5
2014-06-09,The spectral energy distribution of compact jets powered by internal shocks,"Internal shocks caused by fluctuations of the outflow velocity are likely to
power the radio to IR emission of the compact jets of X-ray binaries. The
dynamics of internal shocks and the resulting spectral energy distribution
(SED) of the jet are very sensitive to the time-scales and amplitudes of the
velocity fluctuations injected at the base of the jet. I present a new code
designed to simulate the synchrotron emission of a compact jet powered by
internal shocks. I also develop a semi-analytical formalism allowing one to
estimate the observed SED of the jet as a function of the Power Spectral
Density (PSD) of the assumed fluctuations of the Lorentz factor. I discuss the
cases of a sine modulation of the Lorentz factor and Lorentz factor
fluctuations with a power-law PSD shape. Independently of the details of the
model, the observed nearly flat SEDs are obtained for PSDs of Lorentz factor
fluctuations that are close to a flicker noise spectrum (i.e. P(f)~1/f). The
model also presents a strong wavelength dependent variability that is similar
to that observed in these sources.",1406.2208v1
2016-07-31,Spontaneous Breaking of Lorentz Symmetry with an antisymmetric tensor,"Spontaneous violation of Lorentz symmetry by the vacuum condensation of an
antisymmetric $2$-tensor is considered. The coset construction for nonlinear
realization of spacetime symmetries is employed to build the most general
low-energy effective action for the Goldstone modes interacting with photons.
We analyze the model within the context of the Standard-Model Extension and
noncommutative QED. Experimental bounds for some parameters of the model are
discussed, and we readdress the subtle issues of stability and causality in
Lorentz non-invariant scenarios. Besides the two photon polarizations, just one
Goldstone mode must be dynamical to set a sensible low-energy effective model,
and the enhancement of the stability by accounting interaction terms points to
a protection against observational Lorentz violation.",1608.00829v1
2016-08-08,Searching for photon-sector Lorentz violation using gravitational-wave detectors,"We study the prospects for using interferometers in gravitational-wave
detectors as tools to search for photon-sector violations of Lorentz symmetry.
Existing interferometers are shown to be exquisitely sensitive to tiny changes
in the effective refractive index of light occurring at frequencies around and
below the microhertz range, including at the harmonics of the frequencies of
the Earth's sidereal rotation and annual revolution relevant for tests of
Lorentz symmetry. We use preliminary data obtained by the Laser Interferometer
Gravitational-Wave Observatory (LIGO) in 2006-2007 to place constraints on
coefficients for Lorentz violation in the photon sector exceeding current
limits by about four orders of magnitude.",1608.02592v1
2016-08-09,Search for Lorentz Violation in km$^3$-Scale Neutrino Telescopes,"Kilometer$^3$-scale neutrino detectors such as IceCube, ANTARES, and the
proposed Km3Net neutrino observatory in the Mediterranean have measured, and
will continue to characterize, the atmospheric neutrino spectrum above 1 TeV.
Such precise measurements enable us to probe new neutrino physics, in
particular, those that arise from Lorentz violation. In this paper, we first
relate the effective new physics hamiltonian terms with the Lorentz violating
literature. Second, we calculate the oscillation probability formulas for the
two-level $\nu_\mu-\nu_\tau$ sector. Finally, we comment on some of the
challenges and outlook for this analysis.",1608.02946v1
2016-08-15,An approach to directly probe simultaneity,"The theory of special relativity derives from the Lorentz transformation. The
Lorentz transformation implies differential simultaneity and light speed
isotropy. Experiments to probe differential simultaneity should be able to
distinguish the Lorentz transformation from a kinematically-similar alternate
transformation that predicts absolute simultaneity, the absolute Lorentz
transformation. Here, we describe how published optical tests of light speed
isotropy/anisotropy cannot distinguish between the two transformations. We show
that the shared equations of the two transformations, from the perspective of
the ""stationary"" observer, are sufficient to predict null results in optical
resonator experiments and in tests of frequency changes in one-way light paths.
In an influential 1910 exposition on differential simultaneity, Comstock
described how a ""stationary"" observer would observe different clock readings
for spatially-separated ""moving"" clocks. The difference in clock readings is an
integral aspect of differential simultaneity. We derive the equation for the
difference in clock readings and show that it is equivalent to the Sagnac
correction that describes light speed anisotropies in satellite communications.
We describe an experimental strategy that can measure the differences in
spatially-separated clock times to allow a direct probe of the nature of
simultaneity.",1608.08516v1
2016-12-12,Embeddings and associated spaces of Copson-Lorentz spaces,"Let $m,p,q\in(0,\infty)$ and let $u,v,w$ be nonnegative weights. We
characterize validity of the inequality
  \[
  \left(\int_0^\infty w(t) (f^*(t))^q \, dt \right)^\frac 1q \le C
\left(\int_0^\infty v(t) \left(\int_t^\infty u(s) (f^*(s))^m \,ds \right)^\frac
pm \! dt \right)^\frac 1p
  \] for all measurable functions $f$ defined on $\mathbb{R}^n$ and provide
equivalent estimates of the optimal constant $C>0$ in terms of the weights and
exponents. The obtained conditions characterize the embedding of the
Copson-Lorentz space $CL^{m,p}(u,v)$, generated by the functional
  \[
  \|f\|_{{CL^{m,p}(u,v)}} := \left(\int_0^\infty v(t) \left(\int_t^\infty u(s)
(f^*(s))^m \,ds \right)^\frac pm \! dt \right)^\frac 1p,
  \] into the Lorentz space $\Lambda^q(w)$. Moreover, the results are applied
to describe the associated space of the Copson-Lorentz space ${CL^{m,p}(u,v)}$
for the full range of exponents $m,p\in(0,\infty)$.",1612.03725v2
2016-12-12,Twofold Symmetries of the Pure Gravity Action,"We recast the action of pure gravity into a form that is invariant under a
twofold Lorentz symmetry. To derive this representation, we construct a general
parameterization of all theories equivalent to the Einstein-Hilbert action up
to a local field redefinition and gauge fixing. We then exploit this freedom to
eliminate all interactions except those exhibiting two sets of independently
contracted Lorentz indices. The resulting action is local, remarkably simple,
and naturally expressed in a field basis analogous to the exponential
parameterization of the nonlinear sigma model. The space of twofold Lorentz
invariant field redefinitions then generates an infinite class of equivalent
representations. By construction, all off-shell Feynman diagrams are twofold
Lorentz invariant while all on-shell tree amplitudes are automatically twofold
gauge invariant. We extend our results to curved spacetime and calculate the
analogue of the Einstein equations. While these twofold invariances are hidden
in the canonical approach of graviton perturbation theory, they are naturally
expected given the double copy relations for scattering amplitudes in gauge
theory and gravity.",1612.03927v2
2016-12-19,Lorentz-violating modification of Dirac theory based on spin-nondegenerate operators,"The Standard-Model Extension (SME) parameterizes all possible
Lorentz-violating contributions to the Standard Model and General Relativity.
It can be considered as an effective framework to describe possible
quantum-gravity effects for energies much below the Planck energy. In the
current paper, the spin-nondegenerate operators of the SME fermion sector are
the focus. The propagators, energies, and solutions to the modified Dirac
equation are obtained for several families of coefficients including nonminimal
ones. The particle energies and spinors are computed at first order in Lorentz
violation and, with the optical theorem, they are shown to be consistent with
the propagators. The optical theorem is then also used to derive the matrices
formed from a spinor and its Dirac conjugate at all orders in Lorentz
violation. The results are the first explicit ones derived for the
spin-nondegenerate operators. They will prove helpful for future
phenomenological calculations in the SME that rely on the footing of quantum
field theory.",1612.06221v1
2016-12-20,"Optimizing the Drude-Lorentz model for material permittivity - method, program, and examples for gold, silver, and copper","Approximating the frequency dispersion of the permittivity of materials with
simple analytical functions is of fundamental importance for understanding and
modeling the optical response of materials and resulting structures. In the
generalized Drude-Lorentz model, the permittivity is described in the complex
frequency plane by a number of simple poles having complex weights, which is a
physically relevant and mathematically simple approach: By construction, it
respects causality represents physical resonances of the material, and can be
implemented easily in numerical simulations. We report here an efficient method
of optimizing the fit of measured data with the Drude-Lorentz model having an
arbitrary number of poles. We show examples of such optimizations for gold,
silver, and copper, for different frequency ranges and up to four pairs of
Lorentz poles taken into account. We also provide a program implementing the
method for general use.",1612.06925v2
2017-06-05,Renormalization in a Lorentz-violating model and higher-order operators,"The renormalization in a Lorentz-breaking scalar-spinor higher-derivative
model involving $\phi^4$ self-interaction and the Yukawa-like coupling is
studied. We explicitly de- monstrate that the convergence is improved in
comparison with the usual scalar-spinor model, so, the theory is
super-renormalizable, with no divergences beyond four loops. We compute the
one-loop corrections to the propagators for the scalar and fermionic fields and
show that in the presence of higher-order Lorentz invariance violation, the
poles that dominate the physical theory, are driven away from the standard
on-shell pole mass due to radiatively induced lower dimensional operators. The
new operators change the standard gamma-matrix structure of the two-point
functions, introduce large Lorentz-breaking corrections and lead to
modifications in the renormalization conditions of the theory. We found the
physical pole mass in each sector of our model.",1706.01466v2
2017-07-04,Approximation by Finite Supported Functions,"We consider approximation by functions with finite support and characterize
its approximation spaces in terms of interpolation spaces and Lorentz spaces.",1707.00824v1
2017-07-12,Separability and entanglement of two qubits density matrices using Lorentz transformations,"Explicit separability of general two qubits density matrices is related to
Lorentz transformations. We use the 4-dimensional form R(u,v=0,1,2,3) of the
Hilbert-Schmidt (HS) decomposition of the density matrix. For the generic case
in which Lorentz transformations diagonalize R(u,v=0,1,2,3) (into
s(0),s(1),s(2),s(3)) we give relations between the R parameters and the s
parameters. In particular we consider two cases: a) Two qubits density matrices
with one pair of linear terms in the HS decomposition. b) Two qubits density
matrices with two or three symmetric pairs of linear terms. Some of the
theoretical results are demonstrated by numerical calculations. The four
non-generic cases (which may be reduced to case a) are analyzed and the
non-generic property is related explicitly to Lorentz velocity beta=1 which is
not reachable physically",1707.03696v1
2017-10-12,Emergence of Nonwhite Noise in Langevin Dynamics with Magnetic Lorentz Force,"We investigate the low mass limit of Langevin dynamics for a charged Brownian
particle driven by the magnetic Lorentz force. In the low mass limit, velocity
variables relaxing quickly are coarse-grained out to yield effective dynamics
for position variables. Without Lorentz force, the low mass limit is equivalent
to the high friction limit. Both cases share the same Langevin equation that is
obtained by setting the mass to zero in the original Langevin equation. The
equivalence breaks down in the presence of the Lorentz force. The low mass
limit turns out to be singular. The system in the low mass limit is different
from the system with zero mass. The low mass limit is also different from the
large friction limit. We derive the effective equations of motion in the low
mass limit. The resulting stochastic differential equation involves a nonwhite
noise whose correlation matrix has antisymmetric components. We demonstrate the
importance of the nonwhite noise by investigating the heat dissipation by the
Brownian particle.",1710.04676v1
2017-12-26,Lorentz covariant form of extended higher-spin equations,"The extension of nonlinear higher-spin equations in d=4 proposed in
[arXiv:1504.07289] for the construction of invariant functional is shown to
respect local Lorentz symmetry. The equations are rewritten in a manifestly
Lorentz covariant form resulting from some Stueckelberg-like field
transformation. We also show that the two field-independent central terms
entering higher-spin equations which are not entirely fixed by the consistency
alone get fixed unambiguously by the requirement of Lorentz symmetry. One of
the important advantages of the proposed approach demonstrated in the paper is
the remarkable simplification of the perturbative analysis.",1712.09272v2
2018-09-14,Riemann-Finsler Geometry and Lorentz-Violating Scalar Fields,"The correspondence between Riemann-Finsler geometries and effective field
theories with spin-independent Lorentz violation is explored. We obtain the
general quadratic action for effective scalar field theories in any spacetime
dimension with Lorentz-violating operators of arbitrary mass dimension.
Classical relativistic point-particle lagrangians are derived that reproduce
the momentum-velocity and dispersion relations of quantum wave packets. The
correspondence to Finsler structures is established, and some properties of the
resulting Riemann-Finsler spaces are investigated. The results provide support
for open conjectures about Riemann-Finsler geometries associated with
Lorentz-violating field theories.",1809.05535v2
2018-10-02,Lorentz ratio of a compensated metal,"A violation of the Wiedemann-Franz law in a metal can be quantified by
comparing the Lorentz ratio, $L=\kappa\rho/T$, where $\kappa$ is the thermal
conductivity and $\rho$ is the electrical resistivity, with the universal
Sommerfeld constant, $L_0=(\pi^2/3) (k_B/e)^2$. We obtain the Lorentz ratio of
a clean compensated metal with intercarrier interaction as the dominant
scattering mechanism by solving exactly the system of coupled integral
Boltzmann equations. The Lorentz ratio is shown to assume a particular simple
form in the forward-scattering limit: $L/L_0=\overline{\Theta^2}/2$, where
$\Theta$ is the scattering angle. In this limit, $L/L_0$ can be arbitrarily
small. We also show how the same result can be obtained without the benefit of
an exact solution. We discuss how a strong downward violation of the
Wiedemann-Franz law in a type-II Weyl semimetal WP$_2$ can be explained within
our model.",1810.01463v3
2018-10-08,Testing Lorentz invariance and CPT symmetry using gamma-ray burst neutrinos,"A recent work [Y. Huang and B.-Q. Ma, Commun. Phys. {\bf 1}, 62 (2018)]
associated all four PeV neutrinos observed by IceCube to gamma-ray bursts
(GRBs), and revealed a regularity which indicates a Lorentz violation scale
$E_{\rm LV}=(6.5\pm0.4)\times10^{17}$ GeV with opposite sign factors $s=\pm 1$
between neutrinos and antineutrinos. The association of ""time delay"" and ""time
advance"" events with neutrinos and antineutrinos (or vice versa) is only a
hypothesis since the IceCube detector cannot tell the chirality of the
neutrinos, and further experimental tests are needed to verify this hypothesis.
We derive the values of the CPT-odd Lorentz violating parameters in the
standard-model extension (SME) framework, and perform a threshold analysis on
the electron-positron pair emission of the superluminal neutrinos (or
antineutrinos). We find that different neutrino/antineutrino propagation
properties, suggested by Y. Huang and B.-Q. Ma, can be described in the SME
framework with both Lorentz invariance and CPT symmetry violation, but with a
threshold energy constraint. A viable way on testing the CPT symmetry violation
between neutrinos and antineutrinos is suggested.",1810.03571v2
2019-05-29,Lorentz-violating gaugeon formalism for rank-2 tensor theory,"We develop a BRST symmetric gaugeon formalism for the Abelian rank-2
antisymmetric tensor field in the Lorentz breaking framework. The Lorentz
breaking is achieved here by considering a proper subgroup of Lorentz group
together with translation. In this scenario, the gaugeon fields together with
the standard fields of the Abelian rank-2 antisymmetric tensor theory get mass.
In order to develop the gaugeon formulation for this theory in VSR, we first
introduce a set of dipole vector fields as a quantum gauge freedom to the
action. In order to quantize the dipole vector fields, the VSR-modified
gauge-fixing and corresponding ghost action are constructed as the classical
action is invariant under a VSR-modified gauge transformation. Further, we
present a Type I gaugeon formalism for the Abelian rank-2 antisymmetric tensor
field theory in VSR. The gauge structures of Fock space constructed with the
help of BRST charges are also discussed.",1906.03188v1
2019-06-27,The Uplifting of AdS Type to Quintessence Like Potential Induced by Frozen Large Scale Lorentz Violation,"The quintessence-like potential of vacuum energy can meet the requirement
from both quantum gravity and the accelerating expansion of the universe. The
anti-de Sitter vacuum in string theory has to be lifted to the meta-stable de
Sitter vacuum with positive vacuum energy density to explain the accelerating
expansion of the universe. Based on the possible large scale Lorentz violation,
we define an effective cosmological constant which depends not only on the bare
cosmological constant but also on the Lorentz violation effect. We find the
evolution of the effective cosmological constant exhibits the behavior of
quintessence potential when the bare cosmological constant is from string
landscape in contrary to the existence of local minimum during evolution while
the bare cosmological constant is supplied by the swampland. The critical value
of bare cosmological constant is approximately zero for the behavior
transition. The frozen large scale Lorentz violation can uplift the AdS vacua
to an effective quintessence-like one in this sense.",1906.11860v3
2019-06-27,Obtaining consistent Lorentz gauging for a gravitationally coupled fermion,"For internal gauge forces, the result of locally gauging, i.e., of performing
the substitution $\partial \rightarrow D$, is physically the same whether
performed on the action or on the corresponding Euler-Lagrange equations of
motion. Rather unsettling, though, such commutativity fails for the standard
way of coupling a Dirac fermion to the gravitational field in the setting of a
local Lorentz gauge theory of general relativity in the vierbein formalism, the
equivalence principle thus seemingly being here violated. This paper will
present a formalism in which commutativity holds for the gravitational force as
well, the action for the gravitational field itself being still the
Einstein-Hilbert one. Notably, in this formalism, the spinor field will carry a
world/coordinate index, rather than a Lorentz spinor index as it does
standardly. More generally, no Lorentz indices will figure, neither vector
indices nor spinor indices, which from a parsimonious point of view seems quite
satisfactory.",1906.12200v3
2019-07-02,Lorentz Violation and Radiative Corrections in Gauge Theories,"Various studies have already considered radiative corrections in
Lorentz-violating models unveiling many instances where a minimal or nonminimal
operator generates, via loop corrections, a contribution to the photon sector
of the Standard-Model Extension. However, an important fraction of this
literature does not follow the widely accepted conventions and notations of the
Standard-Model Extension, and this obscures the comparison between different
calculations as well as possible phenomenological consequences. After reviewing
some of these works, we uncover one example where a well defined loop
correction to the $k_{F}$ coefficient, already presented in the literature,
allows us to improve the bounds on one specific coefficient of the fermion
sector of the Lorentz-violating QED extension.",1907.01537v1
2019-07-17,Gravitomagnetism and Gravitational Waves in Galileo-Newtonian Physics,"Adopting Schwinger's formalism for inferring Maxwell-Lorentz equations (MLEs)
and combining three ingredients: (i) the laws of gravitostatics, (ii) the
Galileo-Newton principle of relativity and (iii) existence of gravitational
waves which travel in vacuum with a finite speed $c_g$, we inferred two sets of
gravito-Maxwell-Lorentz Equations (g-MLEs). One of these sets corresponds to
Heaviside's Gravity of 1893 and the other set corresponds to what we call
Maxwellian Gravity (MG). HG and MG are mere two mathematical representations of
a single physical theory called Heaviside-Maxwellian Gravity (HMG). While
rediscovering Heaviside's gravitational field equations following Schwinger's
formalism, we found a correction to Heaviside's speculative gravito-Lorentz
force law. This work presents a Galilo-Newtonian foundation of gravitomagnetic
effects and gravitational waves, caused by time-varying sources and fields,
which are currently considered outside the domain of Newtonian physics. The
emergence HMG from other well-established principles of physics is also noted,
which established its theoretical consistency and fixed the value of $c_g$
uniquely at the speed of light in vacuum. The explanations of certain
experimentally verified general relativistic results within HMG are also noted.
We also report, a set of new Maxwell-Lorentz Equations, physically equivalent
to the standard set, as a byproduct product of the present approach.",1907.09910v1
2019-07-24,Constraining Dimension-Six Nonminimal Lorentz-Violating Electron--Nucleon Interactions with EDM Physics [CPT'19],"Electric dipole moments of atoms can arise from P-odd and T-odd
electron--nucleon couplings. This work studies a general class of dimension-six
electron--nucleon interactions mediated by Lorentz-violating tensors of ranks
ranging from $1$ to $4$. The possible couplings are listed as well as their
behavior under C, P, and T, allowing us to select the couplings compatible with
electric-dipole-moment physics. The unsuppressed contributions of these
couplings to the atom's hamiltonian can be read as equivalent to an electric
dipole moment. The Lorentz-violating coefficients' magnitudes are limited using
electric-dipole-moment measurements at the levels of
$3.2\times10^{-31}\text{(eV)}^{-2}$ or $1.6\times10^{-33}\text{(eV)}^{-2}$.",1907.10538v1
2019-09-16,Lorentz Symmetry Fractionalization and Dualities in (2+1)d,"We discuss symmetry fractionalization of the Lorentz group in (2+1)$d$
non-spin quantum field theory (QFT), and its implications for dualities. We
prove that two inequivalent non-spin QFTs are dual as spin QFTs if and only if
they are related by a Lorentz symmetry fractionalization with respect to an
anomalous $\mathbb{Z}_2$ one-form symmetry. Moreover, if the framing anomalies
of two non-spin QFTs differ by a multiple of 8, then they are dual as spin QFTs
if and only if they are also dual as non-spin QFTs. Applications to summing
over the spin structures, time-reversal symmetry, and level/rank dualities are
explored. The Lorentz symmetry fractionalization naturally arises in
Chern-Simons matter dualities that obey certain spin/charge relations, and is
instrumental for the dualities to hold when viewed as non-spin theories.",1909.07383v2
2019-09-18,Effective Quantum Theory of Black Hole Horizons,"In this paper, we develop an effective quantum theory of black hole horizons
using only the local horizon geometry. On the covariant phase space of the
Holst action admitting Weak Isolated Horizon as an inner boundary, we construct
Hamiltonian charges corresponding to Lorentz symmetries. We show that horizon
area is the Hamiltonian charge corresponding to Lorentz boosts as well as that
for Lorentz rotation which acts on $2$-sphere cross-sections of the horizon.
Using this expression of area as a generator of Lorentz rotation, and the fact
that quantum states residing on the horizon cross-sections carry a
representation of $ISO(2)$, we derive the spectrum of area operator on the
horizon. The eigenstates of this area operator are shown to be labelled by
integers or half integers. The entropy is obtained completely in terms of these
\emph{area quanta} residing on the horizon, and is shown to have exponentially
suppressing corrections to the area law. The formalism is also extended to
non-minimally coupled scalar fields, where the area operator gets modified due
to the value of the scalar field on the horizon.",1909.08351v1
2019-09-30,Exact Lorentz-violating $q$-deformed O($N$) universality class,"We examine the influence of exact Lorentz-violating symmetry mechanism on the
radiative quantum corrections to the critical exponents for massless
$q$-deformed O($N$) $\lambda\phi^{4}$ scalar field theories. For that, we
employ three different and independent field-theoretic renormalization group
methods for computing analytically the $q$-deformed critical exponents up to
next-to-leading order. Then we generalize the former finite loop level results
for any loop order. We show that the Lorentz-violating $q$-deformed critical
exponents, obtained through the three methods, turn out to be identical and
furthermore the same as their Lorentz-invariant $q$-deformed ones. We argue
that this result is in accordance with the universality hypothesis.",1909.13878v1
2019-10-07,Exact Kerr-like solution and its shadow in a gravity model with spontaneous Lorentz symmetry breaking,"We obtain an exact Kerr-like black hole solution by solving the corresponding
gravitational field equations in Einstein-bumblebee gravity model where Lorentz
symmetry is spontaneously broken once a vector field acquires a vacuum
expectation value. Results are presented for the purely radial Lorentz symmetry
breaking. In order to study the effects of this breaking, we consider the black
hole shadow and find that the radial of the unstable spherical orbit on the
equatorial plane $r_c$ decreases with the Lorentz breaking constant $\ell>0$,
and increases with $\ell<0$. These shifts are similar to those of
Einstein-aether black hole. The effect of the LV parameter on the black hole
shadow is that it accelerates the appearance of shadow distortion, and could be
detected by the new generation of gravitational antennas.",1910.02674v2
2020-01-12,Lorentz Invariance of Basis Tensor Gauge Theory,"Basis tensor gauge theory (BTGT) is a vierbein analog reformulation of
ordinary gauge theories in which the vierbein field describes the Wilson line.
After a brief review of the BTGT, we clarify the Lorentz group representation
properties associated with the variables used for its quantization. In
particular, we show that starting from an SO(1,3) representation satisfying the
Lorentz-invariant U(1,3) matrix constraints, BTGT introduces a Lorentz frame
choice to pick the Abelian group manifold generated by the Cartan subalgebra of
u(1,3) for the convenience of quantization even though the theory is frame
independent. This freedom to choose a frame can be viewed as an additional
symmetry of BTGT that was not emphasized before. We then show how an $S_4$
permutation symmetry and a parity symmetry of frame fields natural in BTGT can
be used to construct renormalizable gauge theories that introduce frame
dependent fields but remain frame independent perturbatively without any
explicit reference to the usual gauge field.",2001.03845v2
2020-01-13,The sharp Sobolev type inequalities in the Lorentz--Sobolev spaces in the hyperbolic spaces,"Let $W^1L^{p,q}(\mathbb H^n)$, $1\leq q,p < \infty$ denote the
Lorentz-Sobolev spaces of order one in the hyperbolic spaces $\mathbb H^n$. Our
aim in this paper is three-fold. First of all, we establish a sharp Poincar\'e
inequality in $W^1L^{p,q}(\mathbb H^n)$ with $1\leq q \leq p$ which generalizes
the result in \cite{NgoNguyenAMV} to the setting of Lorentz-Sobolev spaces.
Second, we prove several sharp Poincar\'e-Sobolev type inequalities in
$W^1L^{p,q}(\mathbb H^n)$ with $1\leq q \leq p < n$ which generalize the
results in \cite{NguyenPS2018} to the setting of Lorentz-Sobolev spaces.
Finally, we provide the improved Moser-Trudinger type inequalities in
$W^1L^{n,q}(\mathbb{H}^n)$ in the critical case $p= n$ with $1\leq q \leq n$
which generalize the results in \cite{NguyenMT2018} and improve the results in
\cite{YangLi2019}. In the proof of the main results, we shall prove a
P\'olya--Szeg\""o type principle in $W^1 L^{p,q}(\mathbb H^n)$ with $1\leq q
\leq p$ which maybe is of independent interest.",2001.04018v1
2020-12-04,Bumblebee gravity and particle motion in Snyder noncommutative spacetime structures,"A metric with a Lorentz violating parameter is associated with the bumblebee
gravity model. We study the motion of a particle in this bumblebee background
where the dynamical variables satisfy non-canonical Snyder algebra along with
some critical survey on the classical observations in the bumblebee background
to see how these would likely differ from Schwarzschild background. It has been
found that the perihelion shift acquires a generalized expression with two
independent parameters. One of these two is connected with the Lorentz
violating factor and the other is involved in the Snyder algebraic formulation.
We also observe that the time period of revolution, in general, acquires a
Lorentz violating factor in the bumblebee background, however, for the circular
orbit, it remains unchanged even in the presence of the Lorentz violating
factor in the bumblebee background. The parameters used here can be constrained
with the same type of conjecture used earlier.",2012.02642v1
2020-12-23,"Helicity, Spin, and Infra-zilch of Light: a Lorentz Covariant Formulation","In this paper, a novel conserved Lorentz covariant tensor, termed the
helicity tensor, is introduced in Maxwell theory. The conservation of the
helicity tensor expresses the conservation laws contained in the helicity
array, introduced by Cameron et al., including helicity, spin, and the
spin-flux or infra-zilch. The Lorentz covariance of the helicity tensor is in
contrast to previous formulations of the helicity hierarchy of conservation
laws, which required the non-Lorentz covariant transverse gauge. The helicity
tensor is shown to arise as a Noether current for a variational symmetry of a
duality-symmetric Lagrangian for Maxwell theory. This symmetry transformation
generalizes the duality symmetry and includes the symmetry underlying the
conservation of the spin part of the angular momentum.",2012.12566v2
2021-01-15,Lorentz boosts and Wigner rotations: self-adjoint complexified quaternions,"Herein we shall consider Lorentz boosts and Wigner rotations from a
(complexified) quaternionic point of view. We shall demonstrate that for a
suitably defined self-adjoint complex quaternionic 4-velocity, pure Lorentz
boosts can be phrased in terms of the quaternion square root of the relative
4-velocity connecting the two inertial frames. Straightforward computations
then lead to quite explicit and relatively simple algebraic formulae for the
composition of 4-velocities and the Wigner angle. We subsequently relate the
Wigner rotation to the generic non-associativity of the composition of three
4-velocities, and develop a necessary and sufficient condition for
associativity to hold. Finally, we relate the composition of 4-velocities to a
specific implementation of the Baker-Campbell-Hausdorff theorem. As compared to
ordinary 4x4 Lorentz transformations, the use of self-adjoint complexified
quaternions leads, from a computational view, to storage savings and more rapid
computations, and from a pedagogical view to to relatively simple and explicit
formulae.",2101.05971v1
2017-05-13,CME dynamics using STEREO & LASCO observations: the relative importance of Lorentz forces and solar wind drag,"We seek to quantify the relative contributions of Lorentz forces and
aerodynamic drag on the propagation of solar coronal mass ejections (CMEs). We
use Graduated Cylindrical Shell (GCS) model fits to a representative set of 38
CMEs observed with the SOHO and STEREO spacecraft. We find that the Lorentz
forces generally peak between 1.65 and 2.45 Rsun for all CMEs. For fast CMEs,
Lorentz forces become negligible in comparison to aerodynamic drag as early as
3.5--4 Rsun. For slow CMEs, however, they become negligible only by 12--50
Rsun. For these slow events, our results suggest that some of the magnetic flux
might be expended in CME expansion or heating. In other words, not all of it
contributes to directed propagation. Our results are expected to be important
in building a physical model for understanding the Sun-Earth dynamics of CMEs.",1705.04871v2
2017-05-12,Optimizing the Drude-Lorentz model for material permittivity: Examples for semiconductors,"Approximating the frequency dispersion of the permittivity of materials with
simple analytical functions is of fundamental importance for understanding and
modeling their optical properties. Quite generally, the permittivity can be
treated in the complex frequency plane as an analytic function having a
countable number of simple poles which determine the dispersion of the
permittivity, with the pole weights corresponding to generalized conductivities
of the medium at these resonances. The resulting Drude-Lorentz model separates
the poles at frequencies with zero real part (Ohm's law and Drude poles) from
poles with finite real part (Lorentz poles). To find the parameters of such an
analytic function, we minimize the error weighted deviation between the model
and measured values of the permittivity. We show examples of such optimizations
for various semiconductors (Si, GaAs and Ge), for different frequency ranges
and up to five pairs of Lorentz poles accounted for in the model.",1705.05218v1
2017-05-22,A relativistic quantum oscillator subject to a Coulomb-type potential induced by effects of the violation of the Lorentz symmetry,"We consider a background of the violation of the Lorentz symmetry determined
by the tensor $\left( K_{F}\right)_{\mu\nu\alpha\beta}$ which governs the
Lorentz symmetry violation out of the Standard Model Extension, where this
background gives rise to a Coulomb-type potential, and then, we analyse its
effects on a relativistic quantum oscillator. Furthermore, we analyse the
behaviour of the relativistic quantum oscillator under the influence of a
linear scalar potential and this background of the Lorentz symmetry violation.
We show in both cases that analytical solutions to the Klein-Gordon equation
can be achieved.",1705.07797v1
2017-05-30,Baryogenesis in Lorentz-violating gravity theories,"Lorentz-violating theories of gravity typically contain constrained vector
fields. We show that the lowest-order coupling of such vectors to
$\mathrm{U}(1)$-symmetric scalars can naturally give rise to baryogenesis in a
manner akin to the Affleck-Dine mechanism. We calculate the cosmology of this
new mechanism, demonstrating that a net $B-L$ can be generated in the early
Universe, and that the resulting baryon-to-photon ratio matches that which is
presently observed. We discuss constraints on the model using solar system and
astrophysical tests of Lorentz violation in the gravity sector. Generic
Lorentz-violating theories can give rise to the observed matter-antimatter
asymmetry without violating any current bounds.",1705.10695v1
2017-05-31,Progress on testing Lorentz symmetry with MICROSCOPE,"The Weak Equivalence Principle (WEP) and the local Lorentz invariance (LLI)
are two major assumptions of General Relativity (GR). The MICROSCOPE mission,
currently operating, will perform a test of the WEP with a precision of
$10^{-15}$. The data will also be analysed at SYRTE for the purposes of a LLI
test realised in collaboration with J. Tasson (Carleton College, Minnesota) and
Q. Bailey (Embry-Riddle Aeronautical University, Arizona). This study will be
performed in a general framework, called the Standard Model Extension (SME),
describing Lorentz violations that could appear at Planck scale ($10^{19}$
GeV). The SME allows us to derive a Lorentz violating observable designed for
the MICROSCOPE experiment and to search for possible deviations from LLI in the
differential acceleration of the test masses.",1705.11015v1
2017-09-02,Lorentz violation and generalized uncertainty principle,"Investigations on possible violation of Lorentz invariance have been widely
pursued in the last decades, both from theoretical and experimental sides. A
comprehensive framework to formulate the problem is the standard model
extension (SME) proposed by A.Kostelecky, where violation of Lorentz invariance
is encoded into specific coefficients. Here we present a procedure to link the
deformation parameter $\beta$ of the generalized uncertainty principle (GUP) to
the SME coefficients of the gravity sector. The idea is to compute the Hawking
temperature of a black hole in two different ways. The first way involves the
deformation parameter $\beta$, and therefore we get a deformed Hawking
temperature containing the parameter $\beta$. The second way involves a
deformed Schwarzschild metric containing the Lorentz violating terms
$\bar{s}^{\mu\nu}$ of the gravity sector of the SME. The comparison between the
two different techniques yields a relation between $\beta$ and
$\bar{s}^{\mu\nu}$. In this way bounds on $\beta$ transferred from
$\bar{s}^{\mu\nu}$ are improved by many orders of magnitude when compared with
those derived in other gravitational frameworks. Also the opposite possibility
of bounds transferred from $\beta$ to $\bar{s}^{\mu\nu}$ is briefly discussed.",1709.00637v1
2017-09-04,Detecting Lorentz Violations with Gravitational Waves from Black Hole Binaries,"Gravitational wave observations have been used to test Lorentz symmetry by
looking for dispersive effects that are caused by higher order corrections to
the dispersion relation. In this Letter I argue on general grounds that, when
such corrections are present, there will also be a scalar excitation. Hence, a
smoking-gun observation of Lorentz symmetry breaking would be the direct
detection of scalar waves that travel at a speed other than the speed of the
standard gravitational wave polarisations or the speed of light. Interestingly,
in known Lorentz-breaking gravity theories the difference between the speeds of
scalar and tensor waves is virtually unconstrained, whereas the difference
between the latter and the speed of light is already severely constrained by
the coincident detection of gravitational waves and gamma rays from a binary
neutron star merger.",1709.00940v2
2017-09-14,Equivalence of position-position auto-correlations in the Slicer Map and the Lévy-Lorentz gas,"The Slicer Map is a one-dimensional non-chaotic dynamical system that shows
sub-, super-, and normal diffusion as a function of its control parameter. In a
recent paper [Salari et al., CHAOS 25, 073113 (2015)] it was found that the
moments of the position distributions as the Slicer Map have the same
asymptotic behaviour as the L\'evy-Lorentz gas, a random walk on the line in
which the scatterers are randomly distributed according to a L\'evy-stable
probability distribution. Here we derive analytic expressions for the
position-position correlations of the Slicer Map and, on the ground of this
result, we formulate some conjectures about the asymptotic behaviour of
position-position correlations of the L\'evy-Lorentz gas, for which the
information in the literature is minimal. The numerically estimated
position-position correlations of the L\'evy-Lorentz show a remarkable
agreement with the conjectured asymptotic scaling.",1709.04980v3
2018-06-09,Local Lorentz invariance and a new theory of gravitation equivalent to General Relativity,"A gauge theory of the Lorentz group with a mass-dimension one gauge field
coupling to matter of any spin is developed. As a completely new feature the
""Vierbein"" assuring local gauge invariance enters not as an independent
dynamical field, but emerges as a functional of the Lorentz gauge field. The
underlying geometry of the theory turns out to be a $SO(1,3)$ Banach bundle.
The most general action which is renormalizable by power-counting is
constructed in terms of the gauge field and its first derivatives. It contains
no higher derivative terms in the gauge field which destroy unitarity in the
usual renormalizable $R^2$-theories of gravitation. Finally equivalence of the
Lorentz gauge field theory coupled to spin zero matter with General Relativity
is established",1806.05037v2
2018-07-03,Spacetime and dark matter from spontaneous breaking of Lorentz symmetry,"It is shown that a spontaneously-broken gauge theory of the Lorentz group
contains Ashtekar's chiral formulation of General Relativity accompanied by
dust. From this perspective, gravity is described entirely by a connection
$\omega$ valued in the Lie algebra of the complexified Lorentz group and a
Lorentz-charged scalar field $\tau$. The model is ""pre-geometric"" in the sense
that the spacetime metric may be constructed only in the symmetry-broken
regime. We speculate on the extent to which this dust may account for dark
matter and on the behaviour of the theory in regimes where the symmetry is not
broken.",1807.01100v2
2018-07-13,Limits on Neutrino Lorentz Violation from Multimessenger Observations of TXS 0506+056,"The observation by the IceCube Collaboration of a high-energy ($E \gtrsim
200$ TeV) neutrino from the direction of the blazar TXS 0506+056 and the
coincident observations of enhanced $\gamma$-ray emissions from the same object
by MAGIC and other experiments can be used to set stringent constraints on
Lorentz violation in the propagation of neutrinos that is linear in the
neutrino energy: $\Delta v = - E/M_1$, where $\Delta v$ is the deviation from
the velocity of light, and $M_1$ is an unknown high energy scale to be
constrained by experiment. Allowing for a difference in neutrino and photon
propagation times of $\sim 10$ days, we find that $M_1 \gtrsim 3 \times
10^{16}$ GeV. This improves on previous limits on linear Lorentz violation in
neutrino propagation by many orders of magnitude, and the same is true for
quadratic Lorentz violation.",1807.05155v2
2019-01-30,"Z_3 - graded colour Dirac equations for quarks, confinement and generalized Lorentz symmetries","We propose a modification of standard QCD description of the colour triplet
of quarks describing quark fields endowed with colour degree of freedom by
introducing a 12-component colour generalization of Dirac spinor, with built-in
Z_3 grading playing an important algebraic role in quark confinement. In
""colour Dirac equations"" the SU(3) colour symmetry is entangled with the
Z_3-graded generalization of Lorentz symmetry, containing three 6-parameter
sectors related by Z_3 maps. The generalized Lorentz covariance requires
simultaneous presence of 24 colour Dirac multiplets, which lead to the
description of all internal symmetries of quarks: besides SU(3) \times SU(2)
\times U(1), the flavour symmetries and three quark families.",1901.10936v5
2019-03-13,Poincaré Symmetry from Heisenberg's Uncertainty Relations,"It is noted that the single-variable Heisenberg commutation relation contains
the symmetry of the $Sp(2)$ group which is isomorphic to the Lorentz group
applicable to one time-like dimension and two space-like dimensions, known as
the $O(2,1)$ group. According to Paul A. M. Dirac, from the uncertainty
commutation relations for two variables, it possible to construct the de Sitter
group $O(3,2)$, namely the Lorentz group applicable to three space-like
variables and two time-like variables. By contracting one of the time-like
variables in $O(3,2)$, it is possible, to construct the inhomogeneous Lorentz
group $IO(3,1)$ which serves as the fundamental symmetry group for quantum
mechanics and quantum field theory in the Lorentz covariant world. This
$IO(3,1)$ group is commonly known as the Poincar\'e group.",1903.05348v2
2019-03-20,"$κ$-deformed phase spaces, Jordanian twists, Lorentz-Weyl algebra and dispersion relations","We consider $\kappa$-deformed relativistic quantum phase space and possible
implementations of the Lorentz algebra. There are two ways of performing such
implementations. One is a simple extension where the Poincar\'e algebra is
unaltered, while the other is a general extension where the Poincar\'e algebra
is deformed. As an example we fix the Jordanian twist and the corresponding
realization of noncommutative coordinates, coproduct of momenta and addition of
momenta. An extension with a one-parameter family of realizations of the
Lorentz generators, dilatation and momenta closing the Poincar\'e-Weyl algebra
is considered. The corresponding physical interpretation depends on the way the
Lorentz algebra is implemented in phase space. We show how the spectrum of the
relativistic hydrogen atom depends on the realization of the generators of the
Poincar\'e-Weyl algebra.",1903.08679v3
2019-08-05,Probing of violation of Lorentz invariance by ultracold neutrons in the Standard Model Extension,"We analyze a dynamics of ultracold neutrons (UCNs) caused by interactions
violating Lorentz invariance within the Standard Model Extension (SME)
(Colladay and Kostelecky, Phys. Rev. D55, 6760 (1997) and Kostelecky, Phys.
Rev. D69, 105009 (2004)). We use the effective non-relativistic potential for
interactions violating Lorentz invariance derived by Kostelecky and Lane (J.
Math. Phys. 40, 6245 (1999)) and calculate contributions of these interactions
to the transition frequencies of transitions between quantum gravitational
states of UCNs bouncing in the gravitational field of the Earth. Using the
experimental sensitivity of qBounce experiments we make some estimates of upper
bounds of parameters of Lorentz invariance violation in the neutron sector of
the SME which can serve as a theoretical basis for an experimental analysis. We
show that an experimental analysis of transition frequencies of transitions
between quantum gravitational states of unpolarized and polarized UCNs should
allow to place some new constraints in comparison to the results adduced by
Kostelecky and Russell in Rev. Mod. Phys. 83, 11 (2011); edition 2019, arXiv:
0801.0287v12 [hep-ph].",1908.01498v1
2019-11-22,Lorentz invariance violations in the interplay of quantum gravity with matter,"We explore the interplay of matter with quantum gravity with a preferred
frame to highlight that the matter sector cannot be protected from the
symmetry-breaking effects in the gravitational sector. Focusing on Abelian
gauge fields, we show that quantum gravitational radiative corrections induce
Lorentz-invariance-violating couplings for the Abelian gauge field. In
particular, we discuss how such a mechanism could result in the possibility to
translate observational constraints on Lorentz violation in the matter sector
into strong constraints on the Lorentz-violating gravitational couplings.",1911.10066v2
2019-11-23,Modified black hole solution with a background Kalb-Ramond field,"We study the gravitation effects on a static and spherically symmetric
spacetime due to the vacuum expectation value (VEV) of a Kalb-Ramond field. The
Kalb-Ramond VEV is a background tensor field which produces a local Lorentz
symmetry breaking (LSB) of spacetime. Considering a non-minimal coupling
between the Kalb-Ramond (VEV) and the Ricci tensor, we obtain an exact
parameter-dependent power-law modified black hole. For a particular choice of
the LSB parameter, the Lorentz violation produces a solution similar to the
Reissner-Nordstrom, despite the absence of charge. The near-horizon geometry is
modified by including a new inner horizon and shifting the Schwarzschild
horizon. Asymptotically, the usual Minkowski spacetime with a background tensor
field is recovered. The vacuum configurations are studied considering the
energy conditions and the Lorentz violating source properties. By means of the
mercury perihelion test, an upper bound to the local Lorentz violation (LV) is
obtained, and its corresponding effects on the black hole temperature is
investigated.",1911.10296v2
2020-03-10,Lorentz improving estimates for the $p$-Laplace equations with mixed data,"The aim of this paper is to develop the regularity theory for a weak solution
to a class of quasilinear nonhomogeneous elliptic equations, whose prototype is
the following mixed Dirichlet $p$-Laplace equation of type \begin{align*}
\begin{cases} \mathrm{div}(|\nabla u|^{p-2}\nabla u) &= f+ \
\mathrm{div}(|\mathbf{F}|^{p-2}\mathbf{F}) \qquad \text{in} \ \ \Omega, \\
\hspace{1.2cm} u &=\ g \hspace{3.1cm} \text{on} \ \ \partial \Omega,
\end{cases} \end{align*} in Lorentz space, with given data $\mathbf{F} \in
L^p(\Omega;\mathbb{R}^n)$, $f \in L^{\frac{p}{p-1}}(\Omega)$, $g \in
W^{1,p}(\Omega)$ for $p>1$ and $\Omega \subset \mathbb{R}^n$ ($n \ge 2$)
satisfying a Reifenberg flat domain condition or a $p$-capacity uniform
thickness condition, which are considered in several recent papers. To better
specify our result, the proofs of regularity estimates involve fractional
maximal operators and valid for a more general class of quasilinear
nonhomogeneous elliptic equations with mixed data. This paper not only deals
with the Lorentz estimates for a class of more general problems with mixed data
but also improves the good-$\lambda$ approach technique proposed in our
preceding works~\cite{MPT2018,PNCCM,PNJDE,PNCRM}, to achieve the global Lorentz
regularity estimates for gradient of weak solutions in terms of fractional
maximal operators.",2003.04530v2
2020-05-28,A non-perturbative approach to the scalar Casimir effect with Lorentz symmetry violation,"We determine the effect of Lorentz invariance violation in the vacuum energy
and stress between two parallel plates separated by a distance $L$, in the
presence of a massive real scalar field. We parametrize the Lorentz-violation
in terms of a symmetric tensor $h^{\,\mu\nu}$ that represents a constant
background. Through the Green's function method, we obtain the global Casimir
energy, the Casimir force between the plates and the energy density in a closed
analytical form without resorting to perturbative methods. With regards to the
pressure, we find that $\mathcal{F}_c(L)=\mathcal{F}_0(\tilde{L})/\sqrt{-{\rm
det}\, h^{\,\mu\nu}}$, where $\mathcal{F}_0$ is the Lorentz-invariant
expression, and $\tilde{L}$ is the plate separation rescaled by the component
of $h^{\,\mu\nu}$ normal to the plates, $\tilde{L}=L/\sqrt{-h^{nn}}$. We also
analyze the Casimir stress including finite-temperature corrections. The local
behavior of the Casimir energy density is also discussed.",2005.14217v1
2020-09-04,A field theory in Randers-Finsler spacetime,"Finsler geometry is a natural arena to investigate the physics of spacetimes
with local Lorentz violating. The directional dependence of the Finsler metric
provides a way to encode the Lorentz violating effects into the geometric
structure of spacetime. Here, a classical field theory is proposed in a special
Finsler geometry, the so-called Randers-Finsler spacetime, where the Lorentz
violation is produced by a background vector field. By promoting the
Randers-Finsler metric to a differential operator, a Finsler-invariant action
for the scalar, gauge and fermions are proposed. The theory contains nonlocal
terms, as in the Very Special Relativity based theories. By expanding the
Lagrangian, minimal and nonminimal Standard Model Extension terms arises,
revealing a perturbative Lorentz violation. For a CPT-even term, the
Carrol-Field-Jackiw and derivative extensions are obtained.",2009.03806v1
2020-09-25,Lorentz Resonance in the Homogenization of Plasmonic Crystals,"We explain the Lorentz resonances in plasmonic crystals that consist of 2D
nano dielectric inclusions as the interaction between resonant material
properties and geometric resonances of electrostatic nature. One example of
such plasmonic crystals are graphene nanosheets that are periodically arranged
within a non-magnetic bulk dielectric. We identify local geometric resonances
on the length scale of the small scale period. From a materials perspective,
the graphene surface exhibits a dispersive surface conductance captured by the
Drude model. Together these phenomena conspire to generate Lorentz resonances
at frequencies controlled by the surface geometry and the surface conductance.
The Lorentz resonances found in the frequency response of the effective
dielectric tensor of the bulk metamaterial is shown to be given by an explicit
formula, in which material properties and geometric resonances are decoupled.
This formula is rigorous and obtained directly from corrector fields describing
local electrostatic fields inside the heterogeneous structure. Our analytical
findings can serve as an efficient computational tool to describe the general
frequency dependence of periodic optical devices. As a concrete example, we
investigate two prototypical geometries composed of nanotubes and nanoribbons.",2009.12166v2
2021-02-21,Kink properties in Lorentz-violating scalar field theory,"We consider topological defects for the $\lambda\phi^4$ theory in (1+1)
dimensions with a Lorentz-violating background.
  It has been shown, by M. Barreto et al. (2006) \cite{barreto2006defect}, one
cannot have original effects in (the leading order of) single scalar field
model.
  Here, we introduce a new Lorentz-violating term, next to leading order which
cannot be absorbed by any redefinition of the scalar field or coordinates.
  Our term is the lowest order term which leads to concrete effects on the kink
properties. We calculate the corrections to the kink shape and the
corresponding mass. Quantization of the kink is performed and the revised modes
are obtained. We find the bound and continuum states are affected due to this
Lorentz symmetry violation.",2102.10552v1
2021-03-13,Candidate entanglement invariants for two Dirac spinors,"We consider two spacelike separated Dirac particles and construct five
invariants under the spinor representations of the local proper orthochronous
Lorentz groups. All of the constructed Lorentz invariants are identically zero
for product states. The behaviour of the Lorentz invariants under local unitary
evolutions that act unitarily on any subspace with fixed particle momenta is
studied. All of the Lorentz invariants have invariant absolute values on such
subspaces if the evolutions are generated by local zero-mass Dirac
Hamiltonians. Some of them also for the case of nonzero-mass. Therefore, they
are considered potential candidates for describing spinor entanglement of two
Dirac particles, with either zero or arbitrary mass. Furthermore, their
relations to the Wootters concurrence is investigated and their representations
in the Foldy-Wouthuysen picture is given.",2103.07784v2
2021-03-18,A representation theorem for the Lorentz cone automorphisms,"In this note we prove a representation theorem for the symmetric cone
automorphisms in the spin algebra\, $\Ln$.",2103.09989v1
2021-04-05,A complete set of Lorentz-invariant wave packets and modified uncertainty relation,"We define a set of fully Lorentz-invariant wave packets and show that it
spans the corresponding one-particle Hilbert subspace, and hence the whole Fock
space as well, with a manifestly Lorentz-invariant completeness relation
(resolution of identity). The position-momentum uncertainty relation for this
Lorentz-invariant wave packet deviates from the ordinary Heisenberg uncertainty
principle, and reduces to it in the non-relativistic limit.",2104.01798v4
2021-04-26,Dyson-Schwinger equation approach to Lorentz Symmetry Breaking with finite temperature and chemical potential,"In this work, we investigate the dynamical breakdown of Lorentz symmetry in 4
dimensions by the condensation of a fermionic field described by a Dirac
Lagrangian with a four-fermion interaction. Using the Keldysh formalism we show
that the Lorentz symmetry breaking modifies the Dyson-Schwinger equations of
the fermionic propagator. We analyze the nonperturbative solutions for the
Dyson-Schwinger equations using the combination of the rainbow and quenched
approximations and show that, in equilibrium, the Lorentz symmetry breakdown
can occur in the strong coupling regime and new features arise from this
approach. Finally, we analyze the contributions of temperature and chemical
potential and find the respective phase diagram of the model and analyze the
dependence of the critical temperature and chemical potential as functions of
the coupling constant.",2104.12738v2
2021-06-16,Hamiltonian analysis of fermions coupled to the Holst action,"We report three manifestly Lorentz-invariant Hamiltonian formulations of
minimally and nonminimally coupled fermion fields to the Holst action. These
formulations are achieved by making a suitable parametrization of both the
tetrad and the Lorentz connection, which allows us to integrate out some
auxiliary fields without spoiling the local Lorentz symmetry. They have the
peculiarity that their noncanonical symplectic structures as well as the
phase-space variables for the gravitational sector are real. Moreover, two of
these Hamiltonian formulations involve half-densitized fermion fields. We also
impose the time gauge on these formulations, which leads to real connections
for the gravitational configuration variables. Finally, we perform a
symplectomorphism in one of the manifestly Lorentz-invariant Hamiltonian
formulations and analyze the resulting formulation, which becomes the
Hamiltonian formulation of fermion fields minimally coupled to the Palatini
action for particular values of the coupling parameters.",2106.09049v1
2021-06-29,The Axial Anomaly in Lorentz Violating Theories: Towards the Electromagnetic Response of Weakly Tilted Weyl Semimetals,"Using the path integral formulation in Euclidean space, we extended the
calculation of the abelian chiral anomalies in the case of Lorentz violating
theories by considering a new fermionic correction term provided by the
standard model extension, which arises in the continuous Hamiltonian of a
weakly tilted Weyl semimetal, and whose cones have opposite tilting. We found
that this anomaly is insensitive to the tilting parameter, retaining its
well-known covariant form. This independence on the Lorentz violating
parameters is consistent with other findings reported in the literature. The
initially imposed gauge invariant regularization was consistently recovered at
the end of the calculation by the appearance of highly non-trivial combinations
of the covariant derivatives, which ultimately managed to give only terms
containing the electromagnetic tensor. We emphasize that the value of the
anomaly with an arbitrary parameter is not automatically related to the
effective action describing the electromagnetic response of such materials",2106.15062v1
2021-07-01,Explicit Baker-Campbell-Hausdorff-Dynkin formula for Spacetime via Geometric Algebra,"We present a compact Baker-Campbell-Hausdorff-Dynkin formula for the
composition of Lorentz transformations $e^{\sigma_i}$ in the spin
representation (a.k.a. Lorentz rotors) in terms of their generators $\sigma_i$:
$$
  \ln(e^{\sigma_1}e^{\sigma_2}) =
  \tanh^{-1}\left(\frac{
  \tanh \sigma_1 + \tanh \sigma_2 + \frac12[\tanh \sigma_1, \tanh \sigma_2]
  }{
  1 + \frac12\{\tanh \sigma_1, \tanh \sigma_2\}
  }\right) $$ This formula is general to geometric algebras (a.k.a. real
Clifford algebras) of dimension $\leq 4$, naturally generalising Rodrigues'
formula for rotations in $\mathbb{R}^3$. In particular, it applies to Lorentz
rotors within the framework of Hestenes' spacetime algebra, and provides an
efficient method for composing Lorentz generators. Computer implementations are
possible with a complex $2\times2$ matrix representation realised by the Pauli
spin matrices. The formula is applied to the composition of relativistic
$3$-velocities yielding simple expressions for the resulting boost and the
concomitant Wigner angle.",2107.00343v1
2021-08-22,The convergence rates for the superdiffusion in the Boltzmann-Grad limit of the periodic Lorentz gas,"In this article, we obtain the rates of convergence for superdiffusion in the
Boltzmann-Grad limit of the periodic Lorentz gas, which is one of the
fundamental models to study diffusions in deterministic systems. In their
seminal work, Marklof and Str\""ombergsson proved the Boltzmann-Grad limit of
the periodic Lorentz gas~\cite{M-Sannals2}, and then Marklof and T\'oth
established a superdiffusive central limit theorem in large time for the
Boltzmann-Grad limit~\cite{M-T16}. Based on their work, we apply Stein's method
to derive the convergence rates for the superdiffusion in the Boltzmann-Grad
limit of the periodic Lorentz gas. For the discrete time displacement the rate
of convergence in Wasserstein distance is obtained, while in the context of the
continuous time displacement the result is presented for the Berry-Essen type
bound.",2108.09773v3
2021-11-24,Covariant four dimensional differential calculus in $κ$-Minkowski,"It is generally believed that it is not possible to have a four dimensional
differential calculus in $\kappa$-Minkowski spacetime, with $\kappa$-Poincar\'e
relativistic symmetries, covariant under ($\kappa$-deformed) Lorentz
transformations. Thus, one usually introduces a fifth differential form, whose
physical interpretation is still challenging, and defines a covariant five
dimensional calculus. Nevertheless, the four dimensional calculus is at the
basis of several works based on $\kappa$-Minkowski/$\kappa$-Poincar\'e
framework that led to meaningful insights on its physical interpretation and
phenomenological implications. We here revisit the argument against the
covariance of the four dimensional calculus, and find that it depends crucially
on an incomplete characterization of Lorentz transformations in this framework.
In particular, we understand that this is due to a feature, still uncovered at
the time, that turns out to be fundamental for the consistency of the
relativistic framework: the noncommutativity of the Lorentz transformation
parameters. Once this is taken into account, the four dimensional calculus is
found to be fully Lorentz covariant. The result we obtain extends naturally to
the whole $\kappa$-Poincar\'e algebra of transformations, showing the close
relation between its relativistic nature and the properties of the differential
calculus.",2111.12756v2
2021-11-28,One-loop calculations in CPT-even Lorentz-breaking scalar QED,"In this paper, we study a CPT-even Lorentz-breaking extension of the scalar
QED. For this theory, we calculate the one-loop lower-order contributions in
the Lorentz-violating parameters to the two-point functions of scalar and gauge
fields. We found that the two background tensors, coming from the two sectors
(scalar and gauge) are mixed in the one-loop corrections both in finite and
divergent parts. This shows that these two Lorentz-breaking terms cannot be
studied in an isolated form. Besides, the results in the gauge sector are
confirmed to be transversal.",2111.14257v2
2021-11-29,Non-minimal Lorentz invariance violation in light of muon anomalous magnetic moment and long-baseline neutrino oscillation data,"In light of the increasing hints of new physics at the muon $g-2$ and
neutrino oscillation experiments, we consider the recently observed tension in
the long-baseline neutrino oscillation experiments as a potential indication of
Lorentz invariance violation. For this purpose, the latest data from T2K and
NO$\nu$A is analysed in presence of non-minimal Lorentz invariance violation.
Indeed, we find that isotropic violation in dimensions $D =$ 4, 5 and 6 can
alleviate the tension in neutrino oscillation data by 0.4$-$2.4$\sigma$ CL
significance, with the isotropic coefficient $\gamma^{(5)}_{\tau \tau} =$
3.58$\times$10$^{-32}$GeV$^{-1}$ yielding the best fit. At the same time, the
anomalous muon $g-2$ result can be reproduced with an additional non-isotropic
violation of $d^{zt} =$ -1.7$\times$10$^{-25}$. The analysis highlights the
possibility of simultaneous relaxation of experimental tensions with Lorentz
invariance violation of mixed nature.",2111.14336v2
2021-12-28,Lorentz violation in Dirac and Weyl semimetals,"We propose a correspondence between the description of emergent Lorentz
symmetry in condensed-matter systems and the established general effective
field theory for Lorentz violation in fundamental theories of spacetime and
matter. This correspondence has potential implications in both directions. We
illustrate the proposal by investigating its consequences for the spectral and
transport properties of Dirac and Weyl semimetals. Particular realizations of
this framework give rise to Dirac nodal spectra with nodal lines and rings. We
demonstrate a bulk-boundary correspondence between bulk topological invariants
and drumhead surface states of these Dirac nodal semimetals. We calculate their
transport coefficients in leading-order perturbation theory, thereby
characterizing the unconventional electromagnetic response due to small
deviations from emergent Lorentz invariance. Some prospective future
applications of the correspondence are outlined.",2112.14293v1
2021-12-29,Modified entropy of Kerr-de Sitter black hole in Lorentz symmetry violation theory,"The quantum tunneling radiation of scalar particles near the event horizon of
Kerr-de Sitter black hole is investigated in three systems of coordinates
namely naive coordinate system, Painleve coordinate system and Eddington
coordinate system using Lorentz violation theory in curved space time. The
Klein-Gordon equation of scalar particles is transformed into Hamilton-Jacobi
equation by using Lorentz violation theory in curved space time. We observe
that due to Lorentz violation theory, the expressions of Hawking temperatures,
the Bekenstein-Hawking entropies and specific heat capacities near the event
horizon of Kerr-de Sitter black hole are modified. The Hawking temperatures,
entropies and specific heat capacities increase or decrease depending upon the
choices of ether like vectors $u^\alpha$",2112.14545v2
2021-12-30,A geometric view on local Lorentz transformations in teleparallel gravity,"Local Lorentz transformations play an important role in teleparallel gravity
theories, in which a tetrad is conventionally employed as a fundamental field
variable describing the gravitational field. It is commonly understood that
modifications of general relativity in the teleparallel framework break a
certain notion of local Lorentz invariance, which is present in the pure tetrad
formulation of such theories, while another notion present in the covariant
formulation is preserved. We illuminate these different notions from a
geometric perspective, and distinguish them from what is commonly understood as
breaking of local Lorentz invariance in the context of gravity phenomenology.
Based on physical arguments, we present a geometric interpretation of the
dynamical fields in teleparallel gravity, which unified and refines the
conventional approaches.",2112.15173v1
2022-02-21,Lorentz-covariant kinetic theory for massive spin-1/2 particles,"We construct a matrix-valued spin-dependent distribution function (MVSD) for
massive spin-1/2 fermions and study its properties under Lorentz
transformations. Such transformations result in a Wigner rotation in spin space
and in a nontrivial matrix-valued shift in space-time, which corresponds to the
side jump in the massless case. We express the vector and axial-vector
components of the Wigner function in terms of the MVSD and show that they
transform in a Lorentz-covariant manner. We then construct a manifestly
Lorentz-covariant Boltzmann equation which contains a nonlocal collision term
encoding spin-orbit coupling. Finally, we obtain the spin-dependent
distribution function in local equilibrium by demanding detailed balance.",2202.10160v2
2022-05-11,Semi-transparent boundaries in CPT-even Lorentz violating electrodynamics,"Some aspects of the nonbirefringent CPT-even gauge sector of the Standard
Model Extension (SME), in the vicinity of a semi-transparent mirror, are
investigated in this paper. We first consider a model where the Lorentz
symmetry breaking is caused by a single background vector $v^{\mu}$, and we
obtain perturbative results up to second order in $v^{\mu}$. Specifically, we
compute the modified propagator for the gauge field due to the presence of the
mirror and we analyze the corresponding interaction between the mirror and a
stationary point-like charge. We show that when the charge is placed in the
vicinity of the mirror, a spontaneous torque emerges, which is a new effect
with no counterpart in Maxwell electrodynamics. We also compare these results
with the corresponding ones obtained for the Lorentz violating scalar field
theory. As expected, in the limiting case of perfect mirrors, we recover the
interaction found via the image method. Finally, we discuss how we can extend
these results for a more general Lorentz violating background.",2205.05542v1
2022-05-30,Elimination of Pathological Solutions of the Abraham-Lorentz Equation of Motion,"For more than a century the Abraham-Lorentz equation has generally been
regarded as the correct description of the dynamics of a charged particle.
However, there are pathological solutions of the Abraham-Lorentz equation in
which a particle accelerates in advance of the application of a force, the
so-called preacceleration solutions, and solutions in which the particle
spontaneously accelerates even in the absence of an external force, also known
as runaway solutions. Runaways violate conservation of energy while
preacceleration violates causality. In this work, I will focus on one of the
most used alternative equations of motion: the Landau-Lifshitz equation, which
has no pathological solution. However, it is a first-order approximation to the
Abraham-Lorentz equation, raising the question of how an approximation turns
out to be better than the original. Finally, some numerical results for a
variety of external forces are presented to compare both the equations.",2205.14809v3
2022-06-17,The completeness and separability of function spaces in nonadditive measure theory,"For a nonadditive measure $\mu$, the space $\mathcal{L}^0(\mu)$ of all
measurable functions, the Choquet-Lorentz space $\mathcal{L}^{p,q}(\mu)$, the
Lorentz space of weak type $\mathcal{L}^{p,\infty}(\mu)$, the space
$\mathcal{L}^\infty(\mu)$ of all $\mu$-essentially bounded measurable
functions, and their quotient spaces are defined together with suitable
prenorms on them. Among those function spaces, the Choquet-Lorentz space is
defined by the Choquet integral, while the Lorentz space of weak type is
defined by the Shilkret integral. Then the completeness and separability of
those spaces are investigated. A new characteristic of nonadditive measures,
called property (C), is introduced to establish the Cauchy criterion for
convergence in $\mu$-measure of measurable functions. This criterion and
suitable convergence theorems of the Choquet and Shilkret integrals provide
instruments for carrying out our investigation.",2206.08511v3
2022-07-12,Lorentz-symmetry violation in scenarios of non-linear electromagnetic models: a preliminary inspection,"In this contribution, our efforts consist in presenting and discussing the
status of a paper in progress we are working on to investigate how non-linear
electromagnetic effects couple to the parameters that signal Lorentz-symmetry
violation (LSV). Here, we realize LSV by means of a specific model, namely
Carroll-Field-Jackiw's. We set the formulation by considering a general
non-linear photonic Lagrangian (written in terms of the Lorentz-invariant
bilinears in the field-strength) that may be coupled to different operators
that carry the message of LSV. In possess of the polynomial equation expressing
the dispersion relation and the refractive index, one can find the results that
express how the (meta)material constitutive properties of the vacuum are
affected by the mixing of the parameters that measure LSV with the parameters
of the specific non-linear electrodynamic model under consideration. We expect
that our efforts might be of interest in connection with the experiments
carried out with the existing super-intense LASERs based on chirped pulse
amplification.",2207.05255v1
2022-07-22,A wind environment and Lorentz factors of tens explain gamma-ray bursts X-ray plateau,"Gamma-ray bursts (GRBs) are known to have the most relativistic jets, with
initial Lorentz factors in the order of a few hundreds. Many GRBs display an
early X-ray light-curve plateau, which was not theoretically expected and
therefore puzzled the community for many years. Here, we show that this
observed signal is naturally obtained within the classical GRB ""fireball""
model, provided that the initial Lorentz factor is rather a few tens, and the
expansion occurs into a medium-low density ""wind"". The range of Lorentz factors
in GRB jets is thus much wider than previously thought and bridges an
observational gap between mildly relativistic jets inferred in active galactic
nuclei, to highly relativistic jets deduced in few extreme GRBs. Furthermore,
long GRB progenitors are either not Wolf-Rayet stars, or the wind properties
during the final stellar evolution phase are different than at earlier times.
We discuss several testable predictions of this model.",2207.11066v1
2022-09-12,Lorentz violation in a family of $(1+2)$-dimensional wormhole,"We study neutral Dirac particles confined to a family of $(1+2)$-dimensional
wormholes arising from surfaces of revolution with a constant negative Gaussian
curvature, in the framework of a comprehensive effective field theory allowing
deviations from Lorentz symmetry: the gravitational standard-model extension
(SME). The Dirac particles are described with a fixed background tensor field
that rules the Lorentz symmetry violation in the CPT-even gauge sector of SME.
We implement this geometrical approach by incorporating non-minimal couplings
that possibly induce a Lorentz-symmetry violating term in the modified Dirac
equation. We also analyze the exact analytical solutions of the corresponding
modified Dirac equation in the presence of a peculiar external magnetic field.",2209.05630v2
2022-09-14,Cosmic searches for Lorentz invariance violation,"Cosmic messengers (gamma rays, cosmic rays, neutrinos and gravitational
waves) provide a powerful complementary way to search for Lorentz invariance
violating effects to laboratory-based experiments. The long baselines and high
energies involved make Cherenkov telescopes, air-shower arrays, neutrino
telescopes and gravitational wave detectors unique tools to probe the expected
tiny effects that the breaking of Lorentz invariance would cause in the
propagation of these messengers, in comparison with the standard scenario. In
this chapter we explain the expected effects that the mentioned detectors can
measure and summarize current results of searches for Lorentz violation.",2209.06531v1
2022-09-15,Fermions tunneling of Kerr-Newman-de Sitter black hole in Lorentz violation theory,"In this paper, the tunneling of fermions near the event horizon of
Kerr-Newman-de Sitter black hole is investigated in frame dragging coordinate
systems, Eddington coordinate system and Painleve coordinate system by using
Dirac equation with Lorentz violation theory, Feynman prescription and WKB
approximation. The Hawking temperature, heat capacity and change in
Bekenstein-Hawking entropy are modified due to presence of Lorentz violation
theory. The modified Hawking temperatures, heat capacities and change in
Bekenstein-Hawking entropies near the event horizon of Kerr-Newman-de Sitter
black hole would increase or decrease depending upon the choices of ether like
vectors $u^{\alpha}$. In the absence of Lorentz violation theory, the original
Hawking temperature, entropy and heat capacity are recovered.",2209.07083v1
2022-08-19,On the mathematical description of combined PMD PDL effects in optical communications and how their induced impairments can be minimized,"In this paper it is shown that the correct mathematical framework of combined
polarization mode dispersion and polarization dependent losses (combined
PMD-PDL effects or impairments) in optical fibers is the irreducible spinor
representation of the extended Lorentz Group. Combined PMD-PDL effects are
shown to be formally identical to Lorentz Transformations acting on spin 1/2
zero mass particles. Since there are two different irreducible spinor
representations of the restricted Lorentz Group, there must also exist two
kinds of states of polarizations (SOPs) that are relevant in the description of
PMD-PDL effects. The optical process that allows to convert one kind into the
other is identified as optical phase conjugation. Optical phase conjugation
plays the same role as the time inversion operator in the Lorentz Group
representation theory. A practical and extremely important example of utility
of these ideas, a technique that significantly reduces the PMD-PDL induced
impairments, is presented. This technique allows to cancel the PDL part of the
combined PMD-PDL impairments in a very simple and straightforward way.",2209.07855v4
2022-11-15,Constraining the Lorentz-Violating Bumblebee Vector Field with Big Bang Nucleosynthesis and Gravitational Baryogenesis,"By keeping the cosmological principle i.e., an isotropic and homogeneous
universe, we consider the cosmology of a vector-tensor theory of gravitation
known as the \textit{bumblebee} model. In this model a single Lorentz-violating
timelike vector field with a nonzero vacuum expectation value (VEV) couples to
the Ricci tensor and scalar, as well. Taking the ansatz $B(t)\sim t^\beta$ for
the time evolution of the vector field we derive the relevant dynamic equations
of the Universe, where $\beta$ is a free parameter. In particular, by employing
observational data coming from the Big Bang Nucleosynthesis (BBN) and the
matter-antimatter asymmetry in the Baryogenesis era, we impose some constraints
on the VEV of the bumblebee timelike vector field i.e., $\xi b^2$, and the
exponent parameter $\beta$. The former and the latter limit the size of Lorentz
violation, and the rate of the time evolution of the background
Lorentz-violating bumblebee field, respectively.",2211.07934v2
2022-12-28,Quantum Reference Frames for Lorentz Symmetry,"Since their first introduction, Quantum Reference Frame (QRF) transformations
have been extensively discussed, generalising the covariance of physical laws
to the quantum domain. Despite important progress, a formulation of QRF
transformations for Lorentz symmetry is still lacking. The present work aims to
fill this gap. We first introduce a reformulation of relativistic quantum
mechanics independent of any notion of preferred temporal slicing. Based on
this, we define transformations that switch between the perspectives of
different relativistic QRFs. We introduce a notion of ''quantum Lorentz
transformations'' and ''superposition of Lorentz boosts'', acting on the
external degrees of freedom of a quantum particle. We analyse two effects,
superposition of time dilations and superposition of length contractions, that
arise only if the reference frames exhibit both relativistic and
quantum-mechanical features. Finally, we discuss how the effects could be
observed by measuring the wave-packet extensions from relativistic QRFs.",2212.14081v1
2023-01-02,Modified Hawking temperature and entropy of Kerr-de Sitter black hole in Lorentz violation theory,"In this paper, we discuss the tunneling of scalar particles near the event
horizon of stationary and nonstationary Kerr-de Sitter black hole using Lorentz
violation theory in curved space time. The modified form of Hamilton-Jacobi
equation is derived from the Klein-Gordon equation by applying Lorentz
violation theory. The Hawking temperatures derived from stationary and
nonstationary Kerr-de Sitter black holes are modified due to Lorentz violation
theory. It is noted that the change in Bekenstein-Hawking entropy and modified
Hawking temperatures of stationary and nonstationary Kerr-de Sitter black hole
not only depend on the black hole parameters but also on ether like vectors
${\rm u^\alpha}$.",2301.00571v1
2023-02-12,Quasinormal modes of a scalar perturbation around a rotating BTZ-like black hole in Einstein-bumblebee gravity,"We analytically study the quasinormal modes of a scalar perturbation around a
rotating BTZ-like black hole in the Einstein-bumblebee gravity. We observe that
the Lorentz symmetry breaking parameter imprints only in the imaginary parts of
the quasinormal frequencies for the right-moving and left-moving modes. The
perturbational field decays more rapidly for the negative Lorentz symmetry
breaking parameter, but more slowly for the positive one. The forms of the real
parts are the same as those in the usual BTZ black holes. Moreover, we also
discuss the $AdS/CFT$ correspondence from the quasinormal modes and find that
the Lorentz symmetry breaking parameter enhances the left and right conformal
weights $h_L$ and $h_R$ of the operators dual to the scalar field in the
boundary. These results could be helpful to understand the $AdS/CFT$
correspondence and the Einstein-bumblebee gravity with the Lorentz symmetry
violation.",2302.05861v2
2023-02-17,Lorentz Violation in Neutrino Oscillations using IceCube Atmospheric Neutrino Interferometry,"Lorentz invariance is a fundamental symmetry of spacetime underpinning the
Standard Model (SM) and our understanding of high-energy phenomena in particle
physics. However, beyond the quantum gravity scale, we expect the SM to be
replaced with a more fundamental, covariant theory giving a quantum description
of gravity. The effective theory arising from this theory can break Lorentz
invariance and thus predicts observables that exhibit low-energy manifestations
of Lorentz violation. In particular, these observables could be a subleading
contribution to neutrino oscillations and could therefore explain anomalous
flavor measurements. The Standard Model Extension (SME) formalism describing
such an effective theory predicts terms whose characteristic oscillation length
becomes significant at atmospheric neutrino energies accessible by the IceCube
Neutrino Observatory. We descibe past measurements and efforts to extend these
using ten years of data along with a new energy reconstruction to study
$\nu_{\mu}$ disappearance.",2302.08998v1
2023-03-08,A probabilistic approach to Lorentz balls,"We develop a probabilistic approach to study the volumetric and geometric
properties of unit balls $\mathbb B_{q,1}^n$ of finite-dimensional Lorentz
sequences spaces $\ell_{q,1}^n$. More precisely, we show that the empirical
distribution of a random vector $X^{(n)}$ uniformly distributed on the volume
normalized Lorentz ball in $\mathbb R^n$ converges weakly to a compactly
supported symmetric probability distribution with explicitly given density; as
a consequence we obtain a weak Poincar\'e-Maxwell-Borel principle for any fixed
number $k\in\mathbb N$ of coordinates of $X^{(n)}$ as $n\to\infty$. Moreover,
we prove a central limit theorem for the largest coordinate of $X^{(n)}$,
demonstrating a quite different behavior than in the case of the $\ell_q^n$
balls, where a Gumbel distribution appears in the limit. Last but not least, we
prove a Schechtman-Schmuckenschl\""ager type result for the asymptotic volume of
intersections of volume normalized Lorentz and $\ell^n_p$ balls.",2303.04728v1
2023-03-10,A new bound on Lorentz violation based on the absence of vacuum Cherenkov radiation in ultra-high energy air showers,"In extensive air showers induced by ultra-high energy (UHE) cosmic rays,
secondary particles are produced with energies far above those accessible by
other means. These extreme energies can be used to search for new physics. We
study the effects of isotropic, nonbirefringent Lorentz violation in the photon
sector. In case of a photon velocity smaller than the maximum attainable
velocity of standard Dirac fermions, vacuum Cherenkov radiation becomes
possible. Implementing this Lorentz-violating effect in air shower simulations,
a significant reduction of the calculated average atmospheric depth of the
shower maximum $\left<X_\text{max}\right>$ is obtained. Based on
$\left<X_\text{max}\right>$ and its shower-to-shower fluctuations
$\sigma(X_\text{max})$, a new bound on Lorentz violation is derived which
improves the previous one by a factor of 2. This is the first such bound based
on the absence of vacuum Cherenkov radiation from fundamental particles
(electrons and positrons) in air showers. Options for further improvements are
discussed.",2303.05849v1
2023-04-08,Bosonic Casimir effect in an aether-like Lorentz-violating scenario with higher order derivatives,"In this paper we investigate the bosonic Casimir effect in a
Lorentz-violating symmetry scenario. The theoretical model adopted consists of
a real massive scalar quantum field confined in a region between two large
parallel plates, having its dynamics governed by a modified Klein-Gordon
equation that presents a Lorentz symmetry breaking term. In this context we
admit that the quantum field obeys specific boundary conditions on the plates.
The Lorentz-violating symmetry is implemented by the presence of an arbitrary
constant space-like vector in a CPT-even aether-like approach, considering a
direct coupling between this vector with the derivative of the field in higher
order. The modification on the Klein-Gordon equation produces important
corrections on the Casimir energy and pressure. Thus, we show that these
corrections strongly depend on the order of the higher derivative term and the
specific direction of the constant vector, as well as the boundary conditions
considered.",2304.04078v2
2023-07-06,"Lorentz polarisation, finite lightcone, domain of dependence and isoperimetric inequality in Minkowski spacetime","In this paper, we prove an isoperimetric inequality for the domain of
dependence of a finite lightcone in the Minkowski spacetime of dimension
greater than or equal to $3$. The inequality involves two quantities: the
volume of the domain of dependence, and the perimeter of the finite lightcone.
It states that among all finite lightcones with the same perimeter, the maximal
volume of the domain of dependence is achieved by the spacelike hyperplane
truncated finite lightcone. A novelty of this isoperimetric inequality is the
codimension $2$ comparison feature.
  We introduce the Lorentz polarisation to prove the isoperimetric inequality
by studying the corresponding variational problem. A key observation is the
monotonicity of the domain of dependence of a finite lightcone under the
Lorentz polarisation. We show that any finite lightcone can be transformed by a
sequence of Lorentz polarisations to approximate a spacelike hyperplane
truncated finite lightcone with an equal or less perimeter.",2307.03301v1
2023-07-20,Gravitational waves effects in a Lorentz-violating scenario,"This paper focuses on how the production and polarization of gravitational
waves are affected by spontaneous Lorentz symmetry breaking, which is driven by
a self-interacting vector field. Specifically, we examine the impact of a
smooth quadratic potential and a non-minimal coupling, discussing the
constraints and causality features of the linearized Einstein equation. To
analyze the polarization states of a plane wave, we consider a fixed vacuum
expectation value (VEV) of the vector field. Remarkably, we verify that a
space-like background vector field modifies the polarization plane and
introduces a longitudinal degree of freedom. In order to investigate the
Lorentz violation effect on the quadrupole formula, we use the modified Green
function. Finally, we show that the space-like component of the background
field leads to a third-order time derivative of the quadrupole moment, and the
bounds for the Lorentz-breaking coefficients are estimated as well.",2307.10937v1
2023-09-05,Testing Lorentz invariance violation using cosmogenic neutrinos,"Secondary messengers such as neutrinos and photons are expected to be
produced in interactions of ultra-high-energy cosmic rays (UHECRs) with
extragalactic background photons. Their propagation could be altered by the
effects of Lorentz invariance violation. In this work, we have developed an
extension of the SimProp code that includes some Lorentz-violating scenarios
affecting the propagation of neutrinos. We present the corresponding expected
cosmogenic neutrino fluxes for three different astrophysical scenarios for the
production of UHECRs. These results can be used to put constraints on the scale
of Lorentz violation in the neutrino sector.",2309.02103v2
2023-09-11,Induced Lorentz Violation on a Moving Braneworld,"We consider a braneworld scenario in which a flat 4-D brane, embedded in
$M^{3,1} \times S^1$, is moving on or spiraling around the $S^1$. Although the
induced metric on the brane is 4-D Minkowski, the would-be Lorentz symmetry of
the brane is broken globally by the compactification. As recently pointed out
this means causal bulk signals can propagate superluminally and even backwards
in time according to brane observers. Here we consider the effective action on
the brane induced by loops of bulk fields. We consider a variety of self-energy
and vertex corrections due to bulk scalars and gravitons and show that bulk
loops with non-zero winding generate UV-finite Lorentz-violating terms in the
4-D effective action. The results can be accommodated by the Standard Model
Extension, a general framework for Lorentz-violating effective field theory.",2309.05759v2
2023-10-01,Jet Lorentz factor constraint for GRB 221009A based on the optical depth of the TeV photons,"The recent detection of tera-electronvolt (TeV) photons from the
record-breaking gamma-ray burst GRB 221009A during its prompt phase poses
challenges for constraining its Lorentz factor. We re-evaluate the constraints
on the jet Lorentz factor considering a two-zone model, wherein the TeV photons
originate from the external shock region while the lower energy MeV photons
come from the internal prompt emission region. By properly accounting for the
evolution of the MeV photon spectrum and light curve, we calculate the optical
depth for TeV photons and derive a minimum Lorentz factor about 300. It is
consistent with the afterglow modeling for the TeV emission.",2310.00631v1
2023-10-10,P-v criticality of charged Reissner-Nordstr{ö}m-de Sitter black hole under the influence of Lorentz violation theory,"In this paper, the modified Hawking radiation and the P-v criticality of
Reissner-Nordstr{\""o}m-de Sitter (RNdS) black hole are investigated by using
Dirac equation with Lorentz violation theory in curved space time. Taking
cosmological constant as the thermodynamic pressure and its conjugate quantity
as thermodynamic volume, the analogy between the RNdS black hole in the
ensemble with fixed charge and van der Waals liquid-gas system is derived. We
also study the equation of state, critical exponents, critical point, heat
capacity, entropy correction, Gibbs free energy. It is worth mentioning that
the critical temperature, entropy, Gibbs free energy and Helmholtz free energy
are modified but the critical exponents are found to be unchanged due to the
influence of Lorentz violation theory. We observe that the number of
Hawking-Page critical point increases due to Lorentz violation theory.",2310.06876v1
2023-10-20,Electrically charged black holes in gravity with a background Kalb-Ramond field,"We derive the exact solutions for electrically charged black holes both in
the absence and presence of a cosmological constant in the gravity theory with
Lorentz violation induced by a background Kalb-Ramond (KR) field. The
corresponding thermodynamic properties are investigated. It is found that the
standard first law of thermodynamics and the Smarr formula remain valid for the
charged KR black holes. Nevertheless, the Lorentz-breaking effect influences
their ranges of local thermodynamic stability and the first- and second-order
phase transition points. Furthermore, to examine the impact of Lorentz
violation on the motion of test particles in the spacetime, we analyze the
shadow and the innermost stable circular orbit (ISCO) of these black holes. Our
results reveal that both the shadow and ISCO radii exhibit a high sensitivity
to the Lorentz-violating parameter $\ell$, with a decrease observed as $\ell$
increases.",2310.13555v1
2023-11-21,Tilted Dirac superconductor at quantum criticality: Restoration of Lorentz symmetry,"Lorentz symmetry appears as a quite robust feature of the strongly
interacting Dirac materials even though the lattice interactions break such a
symmetry. We here demonstrate that the Lorentz symmetry is restored at the
quantum-critical point (QCP) separating the tilted Dirac semimetal, breaking
this symmetry already at the noninteracting level, from a gapped $s-$wave
superconducting instability. To this end, we employ a one-loop
$\epsilon=(3-D)-$expansion close to the $D=3$ upper critical dimension of the
corresponding Gross-Neveu-Yukawa field theory. In particular, we show that the
tilt parameter is irrelevant and ultimately vanishes at the QCP separating the
two phases. In fact, as we argue here, such a Lorentz symmetry restoration may
be generic for the strongly interacting tilted Dirac semimetals, irrespective
of whether they feature mirror-symmetric or mirror-asymmetric tilting, and is
also insensitive to whether the instability represents an insulator or a gapped
superconductor. The proposed scenario can be tested in the quantum Monte Carlo
simulations of the interacting tilted Dirac fermion lattice models.",2311.12797v3
2023-12-05,Three Puzzles with Covariance and Supertranslation Invariance of Angular Momentum Flux (with Solutions),"We describe and solve three puzzles arising in covariant and
supertranslation-invariant formulas for the flux of angular momentum and other
Lorentz charges in asymptotically flat spacetimes: 1)
Supertranslation-invariance and covariance imply invariance under spacetime
translations; 2) the flux depends on redundant auxiliary degrees of freedom
that cannot be set to zero in all Lorentz frames without breaking Lorentz
covariance; 3) supertranslation-invariant Lorentz charges do not generate the
transformations of the Bondi mass aspect implied by the isometries of the
asymptotic metric. In this letter, we solve the first two puzzles by presenting
covariant formulas that unambiguously determine the auxiliary degrees of
freedom and clarify the last puzzle by explaining the different role played by
covariant and canonical charges. Our construction makes explicit the choice of
reference frame underpinning seemingly unambiguous results presented in the
current literature.",2312.02458v2
2024-03-21,A survey on Bernstein-type theorems for entire graphical surfaces,"We survey Bernstein-type theorems of graphical surfaces in the Euclidean
space and the Lorentz-Minkowski space. More specifically, we explain several
proofs of the Bernstein theorem for minimal graphs in the Euclidean 3-space.
Furthermore, we show the Heinz-type mean curvature estimates for graphs in the
Euclidean 3-space and space-like graphs in the Lorentz-Minkowski 3-space. As an
application of these estimates, we give Bernstein-type theorems for constant
mean curvature graphs in the Euclidean 3-space and constant mean curvature
space-like graphs in the Lorentz-Minkowski 3-space, respectively. We also study
Bernstein-type results for minimal graphs in the Euclidean 4-space and the
Calabi-Bernstein theorem in the Lorentz-Minkowski 3-space.",2403.14199v1
2024-03-27,Morrey-Lorentz estimates for Hodge-type systems,"We prove up to the boundary regularity estimates in Morrey-Lorentz spaces for
weak solutions of the linear system of differential forms with regular
anisotropic coefficients
  \begin{equation*}
  d^{\ast} \left( A d\omega \right) + B^{\intercal}d d^{\ast} \left( B\omega
\right) = \lambda B\omega + f \text{ in } \Omega,
  \end{equation*}
  with either $ \nu\wedge \omega$ and $\nu\wedge d^{\ast} \left( B\omega
\right)$ or $\nu\lrcorner B\omega$ and
  $\nu\lrcorner \left( A d\omega \right)$ prescribed on $\partial\Omega.$ We
derive these estimates from the $L^{p}$ estimates obtained in
\cite{Sil_linearregularity} in the spirit of Campanato's method. Unlike Lorentz
spaces, Morrey spaces are neither interpolation spaces nor rearrangement
invariant. So Morrey estimates can not be obtained directly from the $L^{p}$
estimates using interpolation. We instead adapt an idea of Lieberman
\cite{Lieberman_morrey_from_Lp} to our setting to derive the estimates.
Applications to Hodge decomposition in Morrey-Lorentz spaces, Gaffney type
inequalities and estimates for related systems such as Hodge-Maxwell systems
and `div-curl' systems are discussed.",2403.18387v1
2024-03-29,Phase structure of the de Sitter Spacetime with KR field based on the Lyapunov exponent,"Since the spontaneously broken of the Lorentz symmetry in the gravity theory
with the non-minimally coupling between the Kalb-Ramond (KR) field (that
acquires a nonzero vacuum expectation value) and the Einstein gravity, there
exists the exactly static and spherically symmetric black holes solutions
related with the Lorentz violating parameter. Based on this, we consider the
corresponding black hole solution in the de-Sitter (dS) spacetime with the KR
field and investigate the thermodynamic properties in the expanded phase space
through introducing the interplay entropy between the black hole and
cosmological horizons. Especially we analyze the effect of the
Lorentz-violating parameter on the thermodynamic properties. Furthermore, the
Lyapunov exponent and the shadow of these static and spherically symmetric
black holes in this Lorentz-violating gravity theory are also investigated.
These study will open a new perspective to probe the thermodynamics of black
holes.",2403.20083v1
1993-08-25,On the Relationship between BL-Lacertae Objects and FRI Radio Galaxies,"The idea that Fanaroff-Riley Class~I Radio Galaxies contain core jets with
Lorentz factors of the order of a few and are the parent population for BL~Lac
Objects is examined, with particular reference to the data on two FRI Radio
Galaxies, NGC~315 and NGC~6251. Conservation laws for an entraining
relativistic jet are derived and are used to determine a relationship between
Mach number and velocity for initially relativistic jets. One immediate
consequence of this relationship is that, if an initially relativistic jet is
decelerated to a transonic Mach number between, say 0.5 and 1.5, then its
velocity at this point is between 0.3 and 0.7 times the speed of light.
Analysis of the milliarcsecond and arcsecond data on NGC~315 and NGC~6251 shows
that the Lorentz factors of the core jets in these galaxies can be as high as
2-4 provided that the jet pressures are not much more than an order of
magnitude higher than the minimum pressures. Such Lorentz factors are more
plausible if the jets are inclined at $\sim 30$ degrees to the line of sight,
although larger angles would also be possible. For core Lorentz factors in the
range 2-4, the jets are mildly relativistic on the large scale and their
velocities are consistent with the jet brightness asymmetries being caused by
Doppler beaming. The Lorentz factors required for significant beaming of core
jets may be reconciled with subluminal motions of knots in the core if these
are reverse shocks advected by the jet. Moderate jet Lorentz factors are
possible if the shocks are normal and higher Lorentz factors are possible if
the shocks are oblique. This paper provides support for the idea that the
transition from two-sided to one-sided jets across the FRI/II break is due to
the transition from",9308033v1
2000-05-15,Relativistic Conic Beams and Spatial Distribution of Gamma-Ray Bursts,"We study the statistics of gamma-ray bursts, assuming that gamma-ray bursts
are cosmological and they are beamed in the form of a conical jet with a large
bulk Lorentz factor $\sim 100$. In such a conic beam, the relativistic ejecta
may have a spatial variation in the bulk Lorentz factor and the density
distribution of gamma-ray emitting jet material. An apparent luminosity
function arises because the axis of the cone is randomly oriented with respect
to the observer's line of sight. The width and the shape of the luminosity
function are determined by the ratio of the beam opening angle of the conical
jet to the inverse of the bulk Lorentz factor, when the bulk Lorentz factor and
the jet material density is uniform on the photon emitting jet surface. We
calculate effects of spatial variation of the Lorentz factor and the spatial
density fluctuations within the cone on the luminosity function and the
statistics of gamma-ray bursts. In particular, we focus on the redshift
distribution of the observed gamma-ray bursts. The maximum distance to and the
average redshift of the gamma-ray bursts are strongly affected by the
beaming-induced luminosity function. The bursts with the angle-dependent
Lorentz factor which peaks at the center of the cone have substantially higher
average gamma-ray burst redshifts. When both the jet material density and the
Lorentz factor are inhomogeneous in the conical beam, the average redshift of
the bursts could be 5 times higher than that of the case in which relativistic
jet is completely homogeneous and structureless. Even the simplest models for
the gamma-ray burst jets and their apparent luminosity distributions have a
significant effect on the redshift distribution of the gamma-ray bursts.",0005302v4
2000-12-18,Gravitational Lorentz Violations and Adjustment of the Cosmological Constant in Asymmetrically Warped Spacetimes,"We investigate spacetimes in which the speed of light along flat 4D sections
varies over the extra dimensions due to different warp factors for the space
and the time coordinates (``asymmetrically warped'' spacetimes). The main
property of such spaces is that while the induced metric is flat, implying
Lorentz invariant particle physics on a brane, bulk gravitational effects will
cause apparent violations of Lorentz invariance and of causality from the brane
observer's point of view. An important experimentally verifiable consequence of
this is that gravitational waves may travel with a speed different from the
speed of light on the brane, and possibly even faster. We find the most general
spacetimes of this sort, which are given by AdS-Schwarzschild or
AdS-Reissner-Nordstrom black holes, assuming the simplest possible sources in
the bulk. Due to the gravitational Lorentz violations these models do not have
an ordinary Lorentz invariant effective description, and thus provide a
possible way around Weinberg's no-go theorem for the adjustment of the
cosmological constant. Indeed we show that the cosmological constant may relax
in such theories by the adjustment of the mass and the charge of the black
hole. The black hole singularity in these solutions can be protected by a
horizon, but the existence of a horizon requires some exotic energy densities
on the brane. We investigate the cosmological expansion of these models and
speculate that it may provide an explanation for the accelerating Universe,
provided that the timescale for the adjustment is shorter than the Hubble time.
In this case the accelerating Universe would be a manifestation of
gravitational Lorentz violations in extra dimensions.",0012143v3
2006-03-01,Spontaneous Lorentz Breaking at High Energies,"Theories that spontaneously break Lorentz invariance also violate
diffeomorphism symmetries, implying the existence of extra degrees of freedom
and modifications of gravity. In the minimal model (``ghost condensation'')
with only a single extra degree of freedom at low energies, the scale of
Lorentz violation cannot be larger than about M ~ 100GeV due to an infrared
instability in the gravity sector. We show that Lorentz symmetry can be broken
at much higher scales in a non-minimal theory with additional degrees of
freedom, in particular if Lorentz symmetry is broken by the vacuum expectation
value of a vector field. This theory can be constructed by gauging ghost
condensation, giving a systematic effective field theory description that
allows us to estimate the size of all physical effects. We show that nonlinear
effects become important for gravitational fields with strength \sqrt{\Phi} >
g, where g is the gauge coupling, and we argue that the nonlinear dynamics is
free from singularities. We then analyze the phenomenology of the model,
including nonlinear dynamics and velocity-dependent effects. The strongest
bounds on the gravitational sector come from either black hole accretion or
direction-dependent gravitational forces, and imply that the scale of
spontaneous Lorentz breaking is M < Min(10^{12}GeV, g^2 10^{15}GeV). If the
Lorentz breaking sector couples directly to matter, there is a spin-dependent
inverse-square law force, which has a different angular dependence from the
force mediated by the ghost condensate, providing a distinctive signature for
this class of models.",0603010v2
2007-04-04,Spontaneous Lorentz Violation: Non-Abelian Gauge Fields as Pseudo-Goldstone Vector Bosons,"We argue that non-Abelian gauge fields can be treated as the pseudo-Goldstone
vector bosons caused by spontaneous Lorentz invariance violation (SLIV). To
this end, the SLIV which evolves in a general Yang-Mills type theory with the
nonlinear vector field constraint $Tr(% \boldsymbol{A}_{\mu
}\boldsymbol{A}^{\mu})=\pm M^{2}$ ($M$ is a proposed SLIV scale) imposed is
considered in detail. With an internal symmetry group $G$ having $D$ generators
not only the pure Lorentz symmetry SO(1,3), but the larger accidental symmetry
$SO(D,3D)$ of the SLIV constraint in itself appears to be spontaneously broken
as well. As a result, while the pure Lorentz violation still generates only one
genuine Goldstone vector boson, the accompanying pseudo-Goldstone vector bosons
related to the $SO(D,3D)$ breaking also come into play in the final arrangement
of the entire Goldstone vector field multiplet. Remarkably, they remain
strictly massless, being protected by gauge invariance of the Yang-Mills theory
involved. We show that, although this theory contains a plethora of Lorentz and
$CPT$ violating couplings, they do not lead to physical SLIV effects which turn
out to be strictly cancelled in all the lowest order processes considered.
However, the physical Lorentz violation could appear if the internal gauge
invariance were slightly broken at very small distances influenced by gravity.
For the SLIV scale comparable with the Planck one the Lorentz violation could
become directly observable at low energies.",0704.0553v5
2016-12-15,The Dynamics of Charged Dust in Magnetized Molecular Clouds,"We study the dynamics of large, charged dust grains in turbulent giant
molecular clouds (GMCs). Massive dust grains behave as aerodynamic particles in
primarily neutral dense gas, and thus are able to produce dramatic small-scale
fluctuations in the dust-to-gas ratio. Hopkins & Lee (2016) directly simulated
the dynamics of neutral dust grains in super-sonic MHD turbulence, typical of
GMCs, and showed that the dust-to-gas fluctuations can exceed factor ~1000 on
small scales, with important implications for star formation, stellar
abundances, and dust behavior and growth. However, even in primarily neutral
gas in GMCs, dust grains are negatively charged and Lorentz forces are
non-negligible. Therefore, we extend our previous study by including the
effects of Lorentz forces on charged grains (in addition to drag). For small
charged grains (sizes <0.1 micron), Lorentz forces suppress dust-to-gas ratio
fluctuations, while for large grains (sizes >1 micron), Lorentz forces have
essentially no effect, trends that are well explained with a simple theory of
dust magnetization. In some special intermediate cases, Lorentz forces can
enhance dust-gas segregation. Regardless, for the physically expected scaling
of dust charge with grain size, we find the most important effects depend on
grain size (via the drag equation) with Lorentz forces/charge as a second-order
correction. We show that the dynamics we consider are determined by three
dimensionless numbers in the limit of weak background magnetic fields: the
turbulent Mach number, a dust drag parameter (proportional to grain size) and a
dust Lorentz parameter (proportional to grain charge); these allow us to
generalize our simulations to a wide range of conditions.",1612.05264v2
2020-01-13,The sharp Adams type inequalities in the hyperbolic spaces under the Lorentz-Sobolev norms,"Let $2\leq m < n$ and $q \in (1,\infty)$, we denote by $W^mL^{\frac
nm,q}(\mathbb H^n)$ the Lorentz-Sobolev space of order $m$ in the hyperbolic
space $\mathbb H^n$. In this paper, we establish the following Adams inequality
in the Lorentz-Sobolev space $W^m L^{\frac nm,q}(\mathbb H^n)$ \[ \sup_{u\in
W^mL^{\frac nm,q}(\mathbb H^n),\, \|\nabla_g^m u\|_{\frac nm,q}\leq 1}
\int_{\mathbb H^n} \Phi_{\frac nm,q}\big(\beta_{n,m}^{\frac q{q-1}} |u|^{\frac
q{q-1}}\big) dV_g < \infty \] for $q \in (1,\infty)$ if $m$ is even, and $q \in
(1,n/m)$ if $m$ is odd, where $\beta_{n,m}^{q/(q-1)}$ is the sharp exponent in
the Adams inequality under Lorentz-Sobolev norm in the Euclidean space. To our
knowledge, much less is known about the Adams inequality under the
Lorentz-Sobolev norm in the hyperbolic spaces. We also prove an improved Adams
inequality under the Lorentz-Sobolev norm provided that $q\geq 2n/(n-1)$ if $m$
is even and $2n/(n-1) \leq q \leq \frac nm$ if $m$ is odd, \[ \sup_{u\in
W^mL^{\frac nm,q}(\mathbb H^n),\, \|\nabla_g^m u\|_{\frac nm,q}^q -\lambda
\|u\|_{\frac nm,q}^q \leq 1} \int_{\mathbb H^n} \Phi_{\frac
nm,q}\big(\beta_{n,m}^{\frac q{q-1}} |u|^{\frac q{q-1}}\big) dV_g < \infty \]
for any $0< \lambda < C(n,m,n/m)^q$ where $C(n,m,n/m)^q$ is the sharp constant
in the Lorentz-Poincar\'e inequality. Finally, we establish a Hardy-Adams
inequality in the unit ball when $m\geq 3$, $n\geq 2m+1$ and $q \geq 2n/(n-1)$
if $m$ is even and $2n/(n-1) \leq q \leq n/m$ if $m$ is odd \[ \sup_{u\in
W^mL^{\frac nm,q}(\mathbb H^n),\, \|\nabla_g^m u\|_{\frac nm,q}^q -C(n,m,\frac
nm)^q \|u\|_{\frac nm,q}^q \leq 1} \int_{\mathbb B^n}
\exp\big(\beta_{n,m}^{\frac q{q-1}} |u|^{\frac q{q-1}}\big) dx < \infty. \]",2001.04017v1
2023-05-20,Tachyonic media in analogue models of special relativity,"In sonic models of special relativity, the fact that the sonic medium
violates (ordinary) Lorentz symmetry is apparent to observers external to the
sonic medium but not to a class of observers existing within the medium itself.
We show that the situation is symmetric: internal observers will judge physics
in the external laboratory to violate their own sonic Lorentz symmetries. We
therefore treat all observers on an equal footing such that each is able to
retain a commitment to their own Lorentz symmetries. We then generalize beyond
the case of subsystem-environment decompositions to situations in which there
exist multiple phonon fields, all obeying Lorentz symmetries but with different
invariant speeds. In such cases, we argue that all observers have freedom to
choose which field is symmetry preserving, and so -- in a certain precise sense
-- which other fields are perceived as having an 'ether.' This choice is
influenced -- but not determined -- by a desire for simplicity in the
description of physical laws. Sending information faster than sound serves as a
model of tachyonic signalling to a distant receiver. Immutable causality of the
laboratory setup when perceived externally to a sonic medium manifests
internally through the confinement of the tachyons to an apparent ether (with a
rest frame), which we call a 'tachyonic medium,' thereby preventing tachyonic
exchange from emulating the scenario of a round-trip signal travelling into an
observer's past causal cone. The assignment of sonic-Lorentz-violating effects
to fields that obey 'photonic' Lorentz symmetries thus ensures that causality
associated with the 'sonic' Lorentz symmetries is preserved.",2305.12113v2
1995-10-27,Radiation Damping and Quantum Excitation for Longitudinal Charged Particle Dynamics in the Thermal Wave Model,"On the basis of the recently proposed {\it Thermal Wave Model (TWM) for
particle beams}, we give a description of the longitudinal charge particle
dynamics in circular accelerating machines by taking into account both
radiation damping and quantum excitation (stochastic effect), in presence of a
RF potential well. The longitudinal dynamics is governed by a 1-D
Schr\""{o}dinger-like equation for a complex wave function whose squared modulus
gives the longitudinal bunch density profile. In this framework, the
appropriate {\it r.m.s. emittance} scaling law, due to the damping effect, is
naturally recovered, and the asymptotic equilibrium condition for the bunch
length, due to the competition between quantum excitation (QE) and radiation
damping (RD), is found. This result opens the possibility to apply the TWM,
already tested for protons, to electrons, for which QE and RD are very
important.",9510004v1
1994-02-04,Constraints on Models of Galaxy Formation from the Evolution of Damped Ly$α$ Absorption Systems,"There is accumulating observational evidence suggesting that damped
Ly$\alpha$ absorption systems systems are the progenitors of present-day spiral
galaxies. We use the observed properties of these systems to place constraints
on the history of star formation in galactic disks, and on cosmological
theories of structure formation in the universe. We show that the observed
increase in $\Omega_{HI}$ contributed by damped Ly$\alpha$ systems at high
redshift implies that star formation must have been considerably less efficient
in the past. We also show that the data can constrain cosmological models in
which structure forms at late epochs. A mixed dark matter (MDM) model with
$\Omega_{\nu}=0.3$ is unable to reproduce the mass densities of cold gas seen
at high redshift, even in the absence of any star formation. We show that at
redshifts greater than 3, this model predicts that the total baryonic mass
contained in dark matter halos with circular velocities $V_c > 35$ km s$^{-1}$
is less than the observed mass of HI in damped systems. At these redshifts, the
photo-ionizing background would prevent gas from dissipating and collapsing to
form high column density systems in halos smaller than 35 km s$^{-1}$. MDM
models are thus ruled out by the observations.",9402015v1
1999-02-11,The HI Column Density Distribution Function at z=0: the Connection to Damped Ly alpha Statistics,"We present a measurement of the HI column density distribution function,
f(N), at the present epoch for column densities log N > 20 cm^-2. These high
column densities compare to those measured in damped Ly alpha lines seen in
absorption against background quasars. Although observationally rare, it
appears that the bulk of the neutral gas in the Universe is associated with
these damped Ly alpha systems. In order to obtain a good anchor point at z=0 we
determine f(N) in the local Universe by using 21cm synthesis observations of a
complete sample of spiral galaxies. We show that f(N) for damped Ly alpha
systems has changed significantly from high z to the present and that change is
greatest for the highest column densities. The measurements indicate that low
surface brightness galaxies make a minor contribution to the cross section for
HI, especially for log N > 21^-2.",9902171v1
2000-10-27,Planetary Torques as the Viscosity of Protoplanetary Disks,"We revisit the idea that density-wave wakes of planets drive accretion in
protostellar disks. The effects of many small planets can be represented as a
viscosity if the wakes damp locally, but the viscosity is proportional to the
damping length. Damping occurs mainly by shocks even for earth-mass planets.
The excitation of the wake follows from standard linear theory including the
torque cutoff. We use this as input to an approximate but quantitative
nonlinear theory based on Burger's equation for the subsequent propagation and
shock. Shock damping is indeed local but weakly so. If all metals in a
minimum-mass solar nebula are invested in planets of a few earth masses each,
dimensionless viscosities [alpha] of order dex(-4) to dex(-3) result. We
compare this with observational constraints. Such small planets would have
escaped detection in radial-velocity surveys and could be ubiquitous. If so,
then the similarity of the observed lifetime of T Tauri disks to the
theoretical timescale for assembling a rocky planet may be fate rather than
coincidence.",0010576v1
2000-12-27,Constraining Dark Matter candidates from structure formation,"We show that collisional damping of adiabatic primordial fluctuations yields
constraints on the possible range of mass and interaction rates of Dark Matter
particles. Our analysis relies on a general classification of Dark Matter
candidates, that we establish independently of any specific particle theory or
model. From a relation between the collisional damping scale and the Dark
Matter interaction rate, we find that Dark Matter candidates must have
cross-sections at decoupling smaller than $ 10^{-33} \frac{m_{dm}}{1 MeV} cm^2$
with photons and $10^{-37} \frac{m_{dm}}{1 MeV} cm^2$ with neutrinos, to
explain the observed primordial structures of $10^9$ Solar mass. These damping
constraints are particularly relevant for Warm Dark Matter candidates. They
also leave open less known regions of parameter space corresponding to
particles having rather high interaction rates with other species than
neutrinos and photons.",0012504v2
2001-07-26,The Contribution of HI-Rich Galaxies to the Damped Absorber Population at z=0,"We present a study of HI-rich galaxies in the local universe selected from
blind emission-line surveys. These galaxies represent the emission-line
counterparts of local damped Lyman-alpha systems. We find that the HI
cross-section of galaxies is drawn from a large range of galaxy masses below
M_star, 66% of the area comes from galaxies in the range 8.5 < Log M_star <
9.7. Both because of the low mass galaxy contribution, and because of the range
of galaxy types and luminosities at any given HI mass, the galaxies
contributing to the HI cross-section are not exclusively L_star spirals, as is
often expected. The optical and near infrared counterparts of these galaxies
cover a range of types (from spirals to irregulars), luminosities (from L_star
to <0.01 L_star), and surface brightnesses. The range of optical and near
infrared properties as well as the kinematics for this population are
consistent with the properties for the low-z damped Lyman-alpha absorbers. We
also show that the number of HI-rich galaxies in the local universe does not
preclude evolution of the low-z damped absorber population, but it is
consistent with no evolution.",0107495v1
2003-11-17,Cosmic Ray Scattering by Compressible Magnetohydrodynamic Turbulence,"Recent advances in understanding of magnetohydrodynamic (MHD) turbulence call
for substantial revisions in the picture of cosmic ray transport. In this paper
we use recently obtained scaling laws for MHD modes to calculate the scattering
frequency for cosmic rays in the ISM. We consider gyroresonance with MHD modes
(Alfvenic, slow and fast) and transit-time damping (TTD) by fast modes. We
provide calculations of cosmic ray scattering for various phases of
interstellar medium with realistic interstellar turbulence driving that is
consistent with the velocity dispersions observed in diffuse gas. We account
for the turbulence cutoff arising from both collisional and collisionless
damping. We obtain analytical expressions for diffusion coefficients that enter
Fokker-Planck equation describing cosmic ray evolution. We calculate the
scattering rate and parallel spatial diffusion coefficients of cosmic rays for
both Alfvenic and fast modes. We conclude that fast modes provides the dominant
contribution to cosmic ray scattering for the typical interstellar conditions
in spite of the fact that fast modes are subjected to damping. We show that the
efficiency of the scattering depends on the plasma beta since it determines the
damping of the fast modes. We also show that the streaming instability is
modified in the presence of turbulence.",0311369v1
2003-11-17,Wave damping by MHD turbulence and its effect upon cosmic ray propagation in the ISM,"Cosmic rays scatter off magnetic irregularities (Alfven waves) with which
they are resonant, that is waves of wavelength comparable to their gyroradii.
These waves may be generated either by the cosmic rays themselves, if they
stream faster than the Alfven speed, or by sources of MHD turbulence. Waves
excited by streaming cosmic rays are ideally shaped for scattering, whereas the
scattering efficiency of MHD turbulence is severely diminished by its
anisotropy. We show that MHD turbulence has an indirect effect on cosmic ray
propagation by acting as a damping mechanism for cosmic ray generated waves.
The hot (``coronal'') phase of the interstellar medium is the best candidate
location for cosmic ray confinement by scattering from self-generated waves. We
relate the streaming velocity of cosmic rays to the rate of turbulent
dissipation in this medium, for the case in which turbulent damping is the
dominant damping mechanism. We conclude that cosmic rays with up to 10^2 GeV
could not stream much faster than the Alfven speed, but that 10^6 GeV cosmic
rays would stream unimpeded by self-generated waves unless the coronal gas were
remarkably turbulence-free.",0311400v1
2004-10-25,Constraints on Dark Matter interactions from structure formation: Damping lengths,"(Shortened) Weakly Interacting Massive Particles are often said to be the
best Dark Matter candidates. Studies have shown however that rather large Dark
Matter-photon or Dark Matter-baryon interactions could be allowed by cosmology.
Here we address the question of the role of the Dark Matter interactions in
more detail to determine at which extent Dark Matter has to be necessarily
weakly interacting. To this purpose, we compute the collisional damping (and
free-streaming) lengths of generic interacting Dark Matter candidates and
compare them to the scale of the smallest primordial structures known to exist
in the Universe. We obtain necessary conditions that any candidate must
satisfy. We point out the existence of new Dark Matter scenarios and exhibit
new damping regimes. For example, an interacting candidate may bear a similar
damping than that of collisionless Warm Dark Matter particles. The main
difference is due to the Dark Matter coupling to interacting (or even
freely-propagating) species. Our approach yields a general classification of
Dark Matter candidates which extends the definitions of the usual Cold, Warm
and Hot Dark Matter scenarios when interactions, weak or strong, are
considered.",0410591v1
2005-10-10,Collisional dissipation of Alfvén waves in a partially ionised solar chromosphere,"Certain regions of the solar atmosphere are at sufficiently low temperatures
to be only partially ionised. The lower chromosphere contains neutral atoms,
the existence of which greatly increases the efficiency of the damping of waves
due to collisional friction momentum transfer. More specifically the Cowling
conductivity can be up to 12 orders of magnitude smaller than the Spitzer
value, so that the main damping mechanism in this region is due to the
collisions between neutrals and positive ions. Using values for the gas density
and temperature as functions of height taken from the VAL C model of the quiet
Sun, an estimate is made for the dependance of the Cowling conductivity on
height and strength of magnetic field. Using both analytic and numerical
approaches the passage of Alfven waves over a wide spectrum through this
partially ionised region is investigated. Estimates of the efficiency of this
region in the damping of Alfven waves are made and compared for both
approaches. We find that Alfven waves with frequencies above 0.6Hz are
completely damped and frequencies below 0.01 Hz unaffected.",0510265v1
2006-04-10,The Nearby Damped Lyman-alpha Absorber SBS 1543+593: A Large HI Envelope in a Gas-Rich Galaxy Group,"We present a Very Large Array (VLA) HI 21cm map and optical observations of
the region around one of the nearest damped Lyman-alpha absorbers beyond the
local group, SBS 1543+593. Two previously uncataloged galaxies have been
discovered and a redshift has been determined for a third. All three of these
galaxies are at the redshift of SBS 1543+593 and are ~185 kpc from the damped
Lyman-alpha absorber. We discuss the HI and optical properties of SBS 1543+593
and its newly identified neighbors. Both SBS 1543+593 and Dwarf 1 have baryonic
components that are dominated by neutral gas -- unusual for damped Lyman-alpha
absorbers for which only ~5% of the HI cross-section originates in such
strongly gas-dominated systems. What remains unknown is whether low mass
gas-rich groups are common surrounding gas-rich galaxies in the local universe
and whether the low star-formation rate in these systems is indicative of a
young system or a stable, slowly evolving system. We discuss these evolutionary
scenarios and future prospects for answering these questions.",0604220v1
2006-08-02,SINS of Viscosity Damped Turbulence,"The problems with explaining the Small Ionized and Neutral Structures (SINS)
appealing to turbulence stem from inefficiency of the Kolmogorov cascade in
creating large fluctuations at sufficiently small scales. However, other types
of cascades are possible. When magnetic turbulence in a fluid with viscosity
that is much larger than resistivity gets to a viscous damping scale, the
turbulence does not vanish. Instead, it gets into a different new regime.
Viscosity-damped turbulence produces fluctuations on the small scales. Magnetic
fields sheared by turbulent motions by eddies not damped by turbulence create
small scale filaments that are confined by the external plasma pressure. This
creates small scale density fluctuations. In addition, extended current sheets
create even stronger density gradients that accompany field reversals in the
plane perpendicular to mean magnetic field. Those can be responsible for the
SINS formation. This scenario is applicable to partially ionized gas. More
studies of reconnection in the viscosity dominated regime are necessary to
understand better the extend to which the magnetic reversals can compress the
gas.",0608046v3
1998-01-13,Comparative Study of the Adiabatic Evolution of a Nonlinear Damped Oscillator and an Hamiltonian Generalized Nonlinear Oscillator,"In this paper we study to what extent the canonical equivalence and the
identity of the geometric phases of dissipative and conservative linear
oscillators, established in a preceeding paper, can be generalized to nonlinear
ones. Considering first the 1-D quartic generalized oscillator we determine, by
means of a perturbative time dependent technic of reduction to normal forms,
the canonical transformations which lead to the adiabatic invariant of the
system and to the first order non linear correction to its Hannay angle. Then,
applying the same transformations to the 1-D quartic damped oscillator we show
that this oscillator is canonically equivalent to the linear generalized
harmonic oscillator for finite values of the damping parameter (which implies
no correction to the linear Hannay angle) whereas, in an appropriate weak
damping limit, it becomes equivalent to the quartic generalized oscillator
(which implies a non linear correction to this angle) .",9801017v1
1995-03-20,Quasiparticle damping in two-dimensional superconductors with unconventional pairing.,"We calculate the damping of excitations due to four-fermionic interaction in
the case of two-dimensional superconductor with nodes in the spectrum. At zero
temperature and low frequencies it reveals gapless $\omega^3$ behavior at the
nodal points. With the frequency increasing the crossover to the normal-state
regimes appears. At high frequencies the damping strongly depends on details of
a normal-state spectrum parametrization. Two important particular cases such as
the models of almost free and tight-binding electrons are studied explicitly
and the characteristic scales are expressed through the model-free parameters
of the spectrum at the nodal points. The possibility of crossover in
temperature dependence of damping in the superconducting phase is discussed.",9503112v1
1996-01-09,Relaxation of Collective Excitations in LJ-13 Cluster,"We have performed classical molecular dynamics simulation of $Ar_{13}$
cluster to study the behavior of collective excitations. In the solid ``phase''
of the cluster, the collective oscillation of the monopole mode can be well
fitted to a damped harmonic oscillator. The parameters of the equivalent damped
harmonic oscillator-- the damping coefficient, spring constant, time period of
oscillation and the mass of the oscillator -- all show a sharp change in
behavior at a kinetic temperature of about $7.0^oK$. This marks yet another
characteristic temperature of the system, a temperature $T_s$ below which
collective excitations are very stable, and at higher temperatures the single
particle excitations cause the damping of the collective oscillations. We argue
that so long as the cluster remains confined within the global potential energy
minimum the collective excitations do not decay; and once the cluster comes out
of this well, the local potential energy minima pockets act as single particle
excitation channels in destroying the collective motion. The effect is manifest
in almost all the physical observables of the cluster.",9601026v2
1997-10-14,Damping of Hydrodynamic Modes in a Trapped Bose Gas above the Bose-Einstein Transition Temperature,"We calculate the damping of low-lying collective modes of a trapped Bose gas
in the hydrodynamic regime, and show that this comes solely from the shear
viscosity, since the contributions from bulk viscosity and thermal conduction
vanish. The hydrodynamic expression for the damping diverges due to the failure
of hydrodynamics in the outer parts of the cloud, and we take this into account
by a physically motivated cutoff procedure. Our analysis of available
experimental data indicates that higher densities than have yet been achieved
are necessary for investigating hydrodynamic modes above the Bose-Einstein
transition temperature.",9710130v2
1997-12-24,Thermal dephasing and the echo effect in a confined Bose-Einstein condensate,"It is shown that thermal fluctuations of the normal component induce
dephasing -- reversible damping of the low energy collective modes of a
confined Bose-Einstein condensate. The dephasing rate is calculated for the
isotropic oscillator trap, where Landau damping is expected to be suppressed.
This rate is characterized by a steep temperature dependence, and it is weakly
amplitude dependent.
  In the limit of large numbers of bosons forming the condensate, the rate
approaches zero. However, for the numbers employed by the JILA group, the
calculated value of the rate is close to the experimental one. We suggest that
a reversible nature of the damping caused by the thermal dephasing in the
isotropic trap can be tested by the echo effect. A reversible nature of Landau
damping is also discussed, and a possibility of observing the echo effect in an
anisotropic trap is considered as well. The parameters of the echo are
calculated in the weak echo limit for the isotropic trap. Results of the
numerical simulations of the echo are also presented.",9712287v1
1998-09-29,Numerical test of the damping time of layer-by-layer growth on stochastic models,"We perform Monte Carlo simulations on stochastic models such as the
Wolf-Villain (WV) model and the Family model in a modified version to measure
mean separation $\ell$ between islands in submonolayer regime and damping time
$\tilde t$ of layer-by-layer growth oscillations on one dimension. The
stochastic models are modified, allowing diffusion within interval $r$ upon
deposited. It is found numerically that the mean separation and the damping
time depend on the diffusion interval $r$, leading to that the damping time is
related to the mean separation as ${\tilde t} \sim \ell^{4/3}$ for the WV model
and ${\tilde t} \sim \ell^2$ for the Family model. The numerical results are in
excellent agreement with recent theoretical predictions.",9809382v1
2000-01-10,Enhanced vortex damping by eddy currents in superconductor-semiconduc tor hybrids,"An enhancement of vortex-motion damping in thin Pb/In superconducting films
is obtained through coupling to an adjacent two-dimensional electron gas formed
in a modulation-doped GaAs/AlGaAs heterostructure. This effect is observed by
monitoring the power dissipation at the superconductor in the vortex state
while increasing the density of the electron gas using a gate voltage.
Quantitative agreement is found with calculations based on a viscous model of
vortex damping which considers generation of eddy currents in the electron gas
by moving flux lines. In the regime of filamentary and channel vortex flow,
eddy-current damping leads to striking dissipation breakdown due to stopping of
entire vortex channels.",0001123v1
2000-10-11,The experimental observation of Beliaev damping in a Bose condensed gas,"We report the first experimental observation of Beliaev damping of a
collective excitation in a Bose-condensed gas. Beliaev damping is not predicted
by the Gross-Pitaevskii equation and so this is one of the few experiments that
tests BEC theory beyond the mean field approximation. Measurements of the
amplitude of a high frequency scissors mode, show that the Beliaev process
transfers energy to a lower lying mode and then back and forth between these
modes. These characteristics are quite distinct from those of Landau damping,
which leads to a monotonic decrease in amplitude. To enhance the Beliaev
process we adjusted the geometry of the magnetic trapping potential to give a
frequency ratio of 2 to 1 between two of the scissors modes of the condensate.
The ratios of the trap oscillation frequencies $\omega_y / \omega_x$ and
$\omega_z / \omega_x$ were changed independently, so that we could investigate
the resonant coupling over a range of conditions.",0010157v1
2001-06-18,AC induced damping of a fluxon in long Josephson junction,"We present a theoretical and experimental study of Josephson vortex (fluxon)
moving in the presence of spatially homogeneous dc and ac bias currents. By
mapping this problem to the problem of calculating the current-voltage
characteristic of a small Josephson junction, we derive the dependence of the
average fluxon velocity on the dc bias current. In particular we find that the
low frequency ac bias current results in an additional nonlinear damping of
fluxon motion. Such ac induced damping crucially depends on the intrinsic
damping parameter and increases drastically as this parameter is reduced. We
find a good agreement of the analysis with both the direct numerical
simulations and the experimentally measured current-voltage characteristics of
a long annular Josephson junction with one trapped fluxon.",0106337v1
2002-03-20,Microscopic nonequilibrium dynamics of an inhomogeneous Bose gas beyond the Born approximation,"Using the prescription of the nonequilibrium statistical operator method, we
derive a non-Markovian generalization to the kinetic theory described by Walser
{\sl et al.} [Phys. Rev. A {\bf 59}, 3878 (1999)]. Quasi-particle damping and
effects arising from the finite duration of a collision are introduced to
include terms beyond the Born approximation. Such a self-consistent theory is
shown to conserve energy to second order in the interaction strength, even in
the Markov limit. This kinetic theory is applied to a simple model of a Bose
gas confined in a spherical trap to study the full real-time evolution towards
equilibrium. A modified form for the damping function, is seen to strongly
improve the energy conservation. Based on a linear response calculation, we
predict the damping rates and frequencies of the collective excitations. We
demonstrate the emergence of differing time scales for damping and
equilibration.",0203415v1
2003-02-17,Magnetization dynamics with a spin-transfer torque,"The magnetization reversal and dynamics of a spin valve pillar, whose lateral
size is 64$\times$64 nm$^2$, are studied by using micromagnetic simulation in
the presence of spin transfer torque. Spin torques display both characteristics
of magnetic damping (or anti-damping) and of an effective magnetic field. For a
steady-state current, both M-I and M-H hysteresis loops show unique features,
including multiple jumps, unusual plateaus and precessional states. These
states originate from the competition between the energy dissipation due to
Gilbert damping and the energy accumulation due to the spin torque supplied by
the spin current. The magnetic energy oscillates as a function of time even for
a steady-state current. For a pulsed current, the minimum width and amplitude
of the spin torque for achieving current-driven magnetization reversal are
quantitatively determined. The spin torque also shows very interesting thermal
activation that is fundamentally different from an ordinary damping effect.",0302337v1
2003-05-12,Landau damping in trapped Bose-condensed gases,"We study Landau damping in dilute Bose-Einstein condensed gases in both
spherical and prolate ellipsoidal harmonic traps. We solve the Bogoliubov
equations for the mode spectrum in both of these cases, and calculate the
damping by summing over transitions between excited quasiparticle states. The
results for the spherical case are compared to those obtained in the
Hartree-Fock approximation, where the excitations take on a single-particle
character, and excellent agreement between the two approaches is found. We have
also taken the semiclassical limit of the Hartree-Fock approximation and obtain
a novel expression for the Landau damping rate involving the time dependent
self-diffusion function of the thermal cloud. As a final approach, we study the
decay of a condensate mode by making use of dynamical simulations in which both
the condensate and thermal cloud are evolved explicitly as a function of time.
A detailed comparison of all these methods over a wide range of sample sizes
and trap geometries is presented.",0305251v1
2003-05-27,Damped finite-time-singularity driven by noise,"We consider the combined influence of linear damping and noise on a dynamical
finite-time-singularity model for a single degree of freedom. We find that the
noise effectively resolves the finite-time-singularity and replaces it by a
first-passage-time or absorbing state distribution with a peak at the
singularity and a long time tail. The damping introduces a characteristic
cross-over time. In the early time regime the probability distribution and
first-passage-time distribution show a power law behavior with scaling exponent
depending on the ratio of the non linear coupling strength to the noise
strength. In the late time regime the behavior is controlled by the damping.
The study might be of relevance in the context of hydrodynamics on a nanometer
scale, in material physics, and in biophysics.",0305630v1
2003-06-05,On Surface Plasmon Damping in Metallic Nanoparticles,"Two possible mechanisms of surface plasmon (SP) oscillations damping in
metallic nanoparticles (MNPs), not connected with electron-phonon interaction
are investigated theoretically: a) the radiation damping of SP, b) resonant
coupling of SP oscillations with electronic transitions in matrix. It is shown
that the radiation damping rate is proportional to the number of electrons in
MNP and therefore this channel of energy outflow from MNP becomes essential for
relatively large particles. The investigation of second mechanism shows that
the rate of SP oscillations energy leakage from MNP dos not depend on particle
size and is fully determined by the optical characteristics of the matrix. It
is demonstrated that for very small MNPs of 3-5 nm size, where the strong 3D
size quantization effect suppresses the electron-phonon interaction, the
resonance coupling in certain cases provides an effective energy outflow.",0306123v1
2003-09-11,Frequency and damping of hydrodynamic modes in a trapped Bose-condensed gas,"Recently it was shown that the Landau-Khalatnikov two-fluid hydrodynamics
describes the collision-dominated region of a trapped Bose condensate
interacting with a thermal cloud. We use these equations to discuss the low
frequency hydrodynamic collective modes in a trapped Bose gas at finite
temperatures. We derive a variational expressions based on these equations for
both the frequency and damping of collective modes. A new feature is our use of
frequency-dependent transport coefficients, which produce a natural cutoff by
eliminating the collisionless low-density tail of the thermal cloud. Above the
superfluid transition, our expression for the damping in trapped inhomogeneous
gases is analogous to the result first obtained by Landau and Lifshitz for
uniform classical fluids. We also use the moment method to discuss the
crossover from the collisionless to the hydrodynamic region. Recent data for
the monopole-quadrupole mode in the hydrodynamic region of a trapped gas of
metastable $^4$He is discussed. We also present calculations for the damping of
the analogous $m=0$ monopole-quadrupole condensate mode in the superfluid
phase.",0309269v1
2003-10-13,Domain wall mobility in nanowires: transverse versus vortex walls,"The motion of domain walls in ferromagnetic, cylindrical nanowires is
investigated numerically by solving the Landau-Lifshitz-Gilbert equation for a
classical spin model in which energy contributions from exchange, crystalline
anisotropy, dipole-dipole interaction, and a driving magnetic field are
considered. Depending on the diameter, either transverse domain walls or vortex
walls are found. The transverse domain wall is observed for diameters smaller
than the exchange length of the given material. Here, the system behaves
effectively one-dimensional and the domain wall mobility agrees with a result
derived for a one-dimensional wall by Slonczewski. For low damping the domain
wall mobility decreases with decreasing damping constant. With increasing
diameter, a crossover to a vortex wall sets in which enhances the domain wall
mobility drastically. For a vortex wall the domain wall mobility is described
by the Walker-formula, with a domain wall width depending on the diameter of
the wire. The main difference is the dependence on damping: for a vortex wall
the domain wall mobility can be drastically increased for small values of the
damping constant up to a factor of $1/\alpha^2$.",0310277v1
2003-11-13,Damping of Bogoliubov Excitations in Optical Lattices,"Extending recent work to finite temperatures, we calculate the Landau damping
of a Bogoliubov excitation in an optical lattice, due to coupling to a thermal
cloud of such excitations. For simplicity, we consider a 1D Bose-Hubbard model
and restrict ourselves to the first energy band. For energy conservation to be
satisfied, the excitations in the collision processes must exhibit ``anomalous
dispersion'', analogous to phonons in superfluid $^4\rm{He}$. This leads to the
disappearance of all damping processes when $U n^{\rm c 0}\ge 6t$, where $U$ is
the on-site interaction, $t$ is the hopping matrix element and $n^{\rm c 0}(T)$
is the number of condensate atoms at a lattice site. This phenomenon also
occurs in 2D and 3D optical lattices. The disappearance of Beliaev damping
above a threshold wavevector is noted.",0311321v1
2004-09-22,Symmetry breaking in driven and strongly damped pendulum,"We examine the conditions for appearance of symmetry breaking bifurcation in
damped and periodically driven pendulum in the case of strong damping. We show
that symmetry breaking, unlike other nonlinear phenomena, can exist at high
dissipation. We prove that symmetry breaking phases exist between phases of
symmetric normal and symmetric inverted oscillations. We find that symmetry
broken solutions occupy a sufficiently smaller region of pendulum's parameter
space in comparison to the statements made in earlier considerations [McDonald
and Plischke, Phys. Rev. B 27 (1983) 201]. Our research on symmetry breaking in
a strongly damped pendulum is relevant to an understanding of phenomena of
dynamic symmetry breaking and rectification in a pure ac driven semiconductor
superlattices.",0409572v1
2004-10-19,Strongly inhibited transport of a 1D Bose gas in a lattice,"We report the observation of strongly damped dipole oscillations of a quantum
degenerate 1D atomic Bose gas in a combined harmonic and optical lattice
potential. Damping is significant for very shallow axial lattices (0.25 photon
recoil energies), and increases dramatically with increasing lattice depth,
such that the gas becomes nearly immobile for times an order of magnitude
longer than the single-particle tunneling time. Surprisingly, we see no
broadening of the atomic quasimomentum distribution after damped motion. Recent
theoretical work suggests that quantum fluctuations can strongly damp dipole
oscillations of 1D atomic Bose gas, providing a possible explanation for our
observations.",0410491v3
2005-08-10,Collective oscillations of a quasi one dimensional Bose condensate under damping,"Influence of the damping on collective oscillations of a one-dimensional
trapped Bose gas in the mean field regime has been studied. Using the
phenomenological damping approach developed by L.P. Pitaevskii, modified
variational equations for the parameters of the condensate wave function is
derived. Analytical expressions for the condensate parameters in equilibrium
state have been obtained. Bistability in nonlinear oscillations of the
condensate under periodic variations of the trap potential is predicted. The
predictions of the modified variational approach are confirmed by full
numerical simulations of the 1D GP equation with the damping.",0508262v1
2005-08-11,Influence of layer defects on the damping in ferroelectric thin films,"A Green's function technique for a modified Ising model in a transverse field
is applied, which allows to calculate the damping of the elementary excitations
and the phase transition temperature of ferroelectric thin films with
structural defects. Based on an analytical expression for the damping function,
we analyze its dependence on temperature, film thickness and interaction
strength numerically. The results demonstrate that defect layers in
ferroelectric thin films, layers with impurities or vacancies as well as layers
with dislocations are able to induce a strong increase of the damping due to
different exchange interactions within the defect layers. The results are in
good agreement with experimental data for thin ferroelectric films with
different thickness.",0508287v1
2006-12-01,Gilbert damping and spin Coulomb drag in a magnetized electron liquid with spin-orbit interaction,"We present a microscopic calculation of the Gilbert damping constant for the
magnetization of a two-dimensional spin-polarized electron liquid in the
presence of intrinsic spin-orbit interaction. First we show that the Gilbert
constant can be expressed in terms of the auto-correlation function of the
spin-orbit induced torque. Then we specialize to the case of the Rashba
spin-orbit interaction and we show that the Gilbert constant in this model is
related to the spin-channel conductivity. This allows us to study the Gilbert
damping constant in different physical regimes, characterized by different
orderings of the relevant energy scales -- spin-orbit coupling, Zeeman
coupling, momentum relaxation rate, spin-momentum relaxation rate, spin
precession frequency -- and to discuss its behavior in various limits.
Particular attention is paid to electron-electron interaction effects,which
enter the spin conductivity and hence the Gilbert damping constant via the spin
Coulomb drag coefficient.",0612015v1
2007-02-23,Parametric Resonance of Optically Trapped Aerosols,"The Brownian dynamics of an optically trapped water droplet are investigated
across the transition from over to under-damped oscillations. The spectrum of
position fluctuations evolves from a Lorentzian shape typical of over-damped
systems (beads in liquid solvents), to a damped harmonic oscillator spectrum
showing a resonance peak. In this later under-damped regime, we excite
parametric resonance by periodically modulating the trapping power at twice the
resonant frequency. The power spectra of position fluctuations are in excellent
agreement with the obtained analytical solutions of a parametrically modulated
Langevin equation.",0702557v1
2007-03-22,Spin-Torque Ferromagnetic Resonance Measurements of Damping in Nanomagnets,"We measure the magnetic damping parameter a in thin film CoFeB and permalloy
(Py) nanomagnets at room temperature using ferromagnetic resonance driven by
microwave frequency spin-transfer torque. We obtain $\alpha_{CoFeB} = 0.014 \pm
0.003$ and $\alpha_{Py}=0.010 \pm 0.002$, values comparable to measurements for
extended thin films, but significantly less than the effective damping
determined previously for similar nanomagnets by fits to time-domain studies of
large-angle magnetic excitations and magnetic reversal. The greater damping
found for the large amplitude nanomagnet dynamics is attributed to the
nonlinear excitation of non-uniform magnetic modes.",0703577v1
2007-02-28,Numerical Model For Vibration Damping Resulting From the First Order Phase Transformations,"A numerical model is constructed for modelling macroscale damping effects
induced by the first order martensite phase transformations in a shape memory
alloy rod. The model is constructed on the basis of the modified
Landau-Ginzburg theory that couples nonlinear mechanical and thermal fields.
The free energy function for the model is constructed as a double well function
at low temperature, such that the external energy can be absorbed during the
phase transformation and converted into thermal form. The Chebyshev spectral
methods are employed together with backward differentiation for the numerical
analysis of the problem. Computational experiments performed for different
vibration energies demonstrate the importance of taking into account damping
effects induced by phase transformations.",0702172v1
2005-04-22,Constraint damping in the Z4 formulation and harmonic gauge,"We show that by adding suitable lower-order terms to the Z4 formulation of
the Einstein equations, all constraint violations except constant modes are
damped. This makes the Z4 formulation a particularly simple example of a
lambda-system as suggested by Brodbeck et al. We also show that the Einstein
equations in harmonic coordinates can be obtained from the Z4 formulation by a
change of variables that leaves the implied constraint evolution system
unchanged. Therefore the same method can be used to damp all constraints in the
Einstein equations in harmonic gauge.",0504114v2
2005-07-05,Universality of Highly Damped Quasinormal Modes for Single Horizon Black Holes,"It has been suggested that the highly damped quasinormal modes of black holes
provide information about the microscopic quantum gravitational states
underlying black hole entropy. This interpretation requires the form of the
highly damped quasinormal mode frequency to be universally of the form:
$\hbar\omega_R = \ln(l)kT_{BH}$, where $l$ is an integer, and $T_{BH}$ is the
black hole temperature. We summarize the results of an analysis of the highly
damped quasinormal modes for a large class of single horizon, asymptotically
flat black holes.",0507019v1
2005-09-07,Massive vector field perturbations in the Schwarzschild background: stability and quasinormal spectrum,"We consider the perturbations of the massive vector field around
Schwarzschild black hole, (generally, with non-vanishing $\Lambda$ - term). The
monopole massive vector perturbation equations can be reduced to a single
wave-like equation. We have proved the stability against these perturbations
and investigated the quasinormal spectrum. The quasinormal behaviour for
Schwarzschild black hole is quite unexpected: the fundamental mode and all
higher overtones shows totally different dependence on the mass of the field
$m$: as $m$ is increasing, the damping rate of the fundamental mode is
decreasing, what results in appearing of the infinitely long living modes,
while, on contrary, damping rate of all higher overtones are increasing, and
their real oscillation frequencies gradually go to tiny values. Thereby, for
all higher overtones, almost non-oscillatory, damping modes can exist. In the
limit of asymptotically high damping, $Re \omega$ goes to $ln3/(8 \pi M)$,
while imaginary part shows equidistant behaviour with spacing $Im \omega_{n+1}-
Im \omega_{n}=i/4M$. In addition, we have found quasinormal spectrum of massive
vector field for Schwarzschild-anti-de Sitter black hole.",0509026v3
2006-11-27,The Mystery of the Asymptotic Quasinormal Modes of Gauss-Bonnet Black Holes,"We analyze the quasinormal modes of $D$-dimensional Schwarzschild black holes
with the Gauss-Bonnet correction in the large damping limit and show that
standard analytic techniques cannot be applied in a straightforward manner to
the case of infinite damping. However, by using a combination of analytic and
numeric techniques we are able to calculate the quasinormal mode frequencies in
a range where the damping is large but finite. We show that for this damping
region the famous $\ln(3)$ appears in the real part of the quasinormal mode
frequency. In our calculations, the Gauss-Bonnet coupling, $\alpha$, is taken
to be much smaller than the parameter $\mu$, which is related to the black hole
mass.",0611139v1
1995-09-22,Damping rate of neutrinos in the singlet Majoron model,"The damping rate and free path of neutrinos in the singlet Majoron model have
been calculated including both finite temperature and symmetry breaking
effects. The behaviour of right- and left-handed fermions are found inherently
different. While the damping rates of the left-handed leptons are essentially
model independent, e.g. directly applicable to the Standard Model, for the
right-handed particles the rates are crucially sensitive to parameters of the
scalar sector. In general, the damping rates are fairly large. The possibility
of the right-handed neutrinos to penetrate deep into the broken phase in the
electroweak phase transition still remains, however, for some parts of
parameter space.",9509359v1
1996-09-25,The hot baryon violation rate is $O(α_W^5 T^4)$,"The rate per unit volume for anomalous electroweak baryon number violation at
high temperatures, in the symmetric phase, has been estimated in the literature
to be $O(\alpha_W^4 T^4)$ based on simple scaling arguments. We argue that
damping effects in the plasma suppress the rate by an extra power of $\alpha_W$
to give $O(\alpha_W^5 T^4)$. We show how to understand this effect in a variety
of ways ranging from an effective description of the long-distance modes
responsible for baryon number violation, to a microscopic picture of the
short-distance modes responsible for damping. In particular, we resolve an old
controversy as to whether damping effects are relevant. Finally, we argue that
similar damping effects should occur in numerical simulations of the rate in
classical thermal field theory on a spatial lattice, and we point out a
potential problem with simulations in the literature that have not found such
an effect.",9609481v1
2001-03-29,Phase transition dynamics in the hot Abelian Higgs model,"We present a detailed numerical study of the equilibrium and non-equilibrium
dynamics of the phase transition in the finite-temperature Abelian Higgs model.
Our simulations use classical equations of motion both with and without
hard-thermal-loop corrections, which take into account the leading quantum
effects. From the equilibrium real-time correlators, we determine the Landau
damping rate, the plasmon frequency and the plasmon damping rate. We also find
that, close to the phase transition, the static magnetic field correlator shows
power-law magnetic screening at long distances. The information about the
damping rates allows us to derive a quantitative prediction for the number
density of topological defects formed in a phase transition. We test this
prediction in a non-equilibrium simulation and show that the relevant time
scale for defect formation is given by the Landau damping rate.",0103311v1
1996-04-12,Onset of Rotational Damping in Superdeformed Nuclei,"We discuss damping of the collective rotational motion in $A\sim 150$
superdeformed nuclei by means of a shell model combining the cranked Nilsson
mean-filed and the surface-delta two-body residual force. It is shown that,
because of the shell structure associated with the superdeformed mean-field,
onset energy of the rotational damping becomes $E_x \sim 2-3 $ MeV above yrast
line, which is much higher than in normal deformed nuclei. The mechanism of the
shell structure effect is investigated through detailed analysis of level
densities in superdeformed nuclei. It is predicted the onset of damping varies
in different supedeformed nuclei along with variation in the single-particle
structure at the Fermi surface.",9604015v1
2001-09-12,The damping width of giant dipole resonances of cold and hot nuclei: a macroscopic model,"A phenomenological macroscopic model of the Giant Dipole Resonance (GDR)
damping width of cold- and hot-nuclei with ground-state spherical and
near-spherical shapes is developed. The model is based on a generalized Fermi
Liquid model which takes into account the nuclear surface dynamics. The
temperature dependence of the GDR damping width is accounted for in terms of
surface- and volume-components. Parameter-free expressions for the damping
width and the effective deformation are obtained. The model is validated with
GDR measurements of the following nuclides, $^{39,40}$K, $^{42}$Ca, $^{45}$Sc,
$^{59,63}$Cu, $^{109-120}$Sn,$^{147}$Eu, $^{194}$Hg, and $^{208}$Pb, and is
compared with the predictions of other models.",0109034v1
2006-01-31,Small damping approach in Fermi-liquid theory,"The validity of small damping approximation (SDA) for the quasi-classical
description of the averaged properties of nuclei at high temperatures is
studied within the framework of collisional kinetic theory. The isoscalar
collective quadrupole vibrations in hot nuclei are considered. We show that the
extension of the SDA, by accounting for the damping of the distribution
function $\delta f$ in the collision integral reduces the rate of variation
with temperature of the Fermi surface distortion effects. The damping of the
$\delta f$ in the collision integral increases significantly the collisional
width of the giant quadrupole resonance (GQR) for small enough values of the
relaxation time. The temperature dependence of the eigenenergy of the GQR
becomes much more weaker than in the corresponding SDA case.",0601094v1
2001-11-05,Damping of transversal plasma-electron oscillations and waves in low-collision electron-ion plasmas,"Previously developed method for finding asymptotic solutions of Vlasov
equations using two-dimensional (in coordinate x and time t) Laplace transform
is here applied to consider transversal oscillations and waves in low-collision
quasi-neutral (n_i \simeq n_e) Maxwellian electron-ion plasmas. We obtain two
branches of electron waves: the ubiquitous one of high-frequency and
high-velocity oscillations and the unusual low-velocity one. Taking into
account Coulomb collisions in the limit m_e << m_i, \bar{v_i} << \bar{v_e}, and
T_e m_e << T_i m_i results in expressions for transversal plasma-electron
oscillation/wave decrements with a damping of the low-velocity electron branch
\sim n_i^{1/3}/\bar{v}_e^{4/3}, where n_i is the ion density and \bar{v}_e is
the mean electron velocity. It ought to rehabilitate Vlasov principal value
prescription for relevant integrals, but to supplement it with representation
of an asymptotical solution as a sum of exponents (not a single one).
""Non-damping"" kinematical waves in low-collision plasma transform in the
damping ones at reasonably chosen iteration process.",0111014v3
2002-03-13,Enhanced radiative ion cooling,"Enhanced radiative cooling of ion beams in storage rings and Robinson's
damping criterion are discussed.",0203036v1
2003-05-24,Impact of the Wiggler Coherent Synchrotron Radiation Impedance on the Beam Instability,"Coherent Synchrotron Radiation (CSR) can play an important role by not only
increasing the energy spread and emittance of a beam, but also leading to a
potential instability. Previous studies of the CSR induced longitudinal
instability were carried out for the CSR impedance due to dipole magnets.
However, many storage rings include long wigglers where a large fraction of the
synchrotron radiation is emitted. This includes high-luminosity factories such
as DAPHNE, PEP-II, KEK-B, and CESR-C as well as the damping rings of future
linear colliders. In this paper, the instability due to the CSR impedance from
a wiggler is studied assuming a large wiggler parameter $K$. The primary
consideration is a low frequency microwave-like instability, which arises near
the pipe cut-off frequency. Detailed results are presented on the growth rate
and threshold for the damping rings of several linear collider designs.
Finally, the optimization of the relative fraction of damping due to the
wiggler systems is discussed for the damping rings.",0305107v1
2004-09-13,Landau damping in thin films irradiated by a strong laser field,"The rate of linear collisionless damping (Landau damping) in a classical
electron gas confined to a heated ionized thin film is calculated. The general
expression for the imaginary part of the dielectric tensor in terms of the
parameters of the single-particle self-consistent electron potential is
obtained. For the case of a deep rectangular well, it is explicitly calculated
as a function of the electron temperature in the two limiting cases of specular
and diffuse reflection of the electrons from the boundary of the
self-consistent potential. For realistic experimental parameters, the
contribution of Landau damping to the heating of the electron subsystem is
estimated. It is shown that for films with a thickness below about 100 nm and
for moderate laser intensities it may be comparable with or even dominate over
electron-ion collisions and inner ionization.",0409062v1
1996-06-24,Quantum damping of position due to energy measurements,"Quantum theory for measurements of energy is introduced and its consequences
for the average position of monitored dynamical systems are analyzed. It turns
out that energy measurements lead to a localization of the expectation values
of other observables. This is manifested, in the case of position, as a damping
of the motion without classical analogue. Quantum damping of position for an
atom bouncing on a reflecting surface in presence of a homogeneous
gravitational field is dealt in detail and the connection with an experiment
already performed in the classical regime is studied. We show that quantum
damping is testable provided that the same measurement strength obtained in the
experimental verification of the quantum Zeno effect in atomic spectroscopy [W.
M. Itano et al., Phys. Rev. A {\bf 41}, 2295 (1990)] is made available.",9606024v1
2006-12-17,Influence of a classical homogeneous gravitational field on dissipative dynamics of the Jaynes-Cummings model with phase damping,"In this paper, we study the dissipative dynamics of the Jaynes-Cummings model
with phase damping in the presence of a classical homogeneous gravitational
field. The model consists of a moving two-level atom simultaneously exposed to
the gravitational field and a single-mode traveling radiation field in the
presence of the phase damping. We present a quantum treatment of the internal
and external dynamics of the atom based on an alternative su(2) dynamical
algebraic structure. By making use of the super-operator technique, we obtain
the solution of the master equation for the density operator of the quantum
system, under the Markovian approximation. Assuming that initially the
radiation field is prepared in a Glauber coherent state and the two-level atom
is in the excited state, we investigate the influence of gravity on the
temporal evolution of collapses and revivals of the atomic population
inversion, atomic dipole squeezing, atomic momentum diffusion, photon counting
statistics and quadrature squeezing of the radiation field in the presence of
phase damping.",0612143v2
2007-04-25,Theory of weakly damped free-surface flows: a new formulation based on potential flow solutions,"Several theories for weakly damped free-surface flows have been formulated.
In this paper we use the linear approximation to the Navier-Stokes equations to
derive a new set of equations for potential flow which include dissipation due
to viscosity. A viscous correction is added not only to the irrotational
pressure (Bernoulli's equation), but also to the kinematic boundary condition.
The nonlinear Schr\""odinger (NLS) equation that one can derive from the new set
of equations to describe the modulations of weakly nonlinear, weakly damped
deep-water gravity waves turns out to be the classical damped version of the
NLS equation that has been used by many authors without rigorous justification.",0704.3352v1
2007-05-25,The Secular Evolution of a Close Ring-Satellite System: The Excitation of Spiral Bending Waves at a Nearby Gap Edge,"The secular perturbations exerted by an inclined satellite orbiting in a gap
in a broad planetary ring tends to excite the inclinations of the nearby ring
particles, and the ring's self-gravity can allow that disturbance to propagate
away in the form of a spiral bending wave. The amplitude of this spiral bending
wave is determined, as well as the wavelength, which shrinks as the waves
propagate outwards due to the effects of the central planet's oblateness. The
excitation of these bending waves also damps the satellite's inclination I.
This secular I damping is also compared to the inclination excitation that is
due to the satellite's many other vertical resonances in the ring, and the
condition for inclination damping is determined. The secular I damping is
likely responsible for confining the orbits of Saturn's two known gap-embedded
moons, Pan and Daphnis, to the ring plane.",0705.3797v1
2007-06-15,Anticorrelation between temperature and fluctuations in moderately damped Josephson junctions,"We study the influence of dissipation on the switching current statistics of
moderately damped Josephson junctions. Different types of both low- and high-
$T_c$ junctions with controlled damping are studied. The damping parameter of
the junctions is tuned in a wide range by changing temperature, magnetic field,
gate voltage, introducing a ferromagnetic layer or in-situ capacitive shunting.
A paradoxical collapse of switching current fluctuations occurs with increasing
$T$ in all studied junctions. The phenomenon critically depends on dissipation
in the junction and is explained by interplay of two counteracting consequences
of thermal fluctuations, which on the one hand assist in premature switching
into the resistive state and on the other hand help in retrapping back to the
superconducting state. This is one of the rare examples of anticorrelation
between temperature and fluctuation amplitude of a physically measurable
quantity.",0706.2248v1
2007-08-06,Collisionless damping of electron waves in non-Maxwellian plasma,"In this paper we have criticized the so-called Landau damping theory. We have
analyzed solutions of the standard dispersion equations for longitudinal
(electric) and transversal (electromagnetic and electron) waves in
half-infinite slab of the uniform collisionless plasmas with non-Maxwellian and
Maxwellian-like electron energy distribution functions. One considered the most
typical cases of both the delta-function type distribution function (the plasma
stream with monochromatic electrons) and distribution functions, different from
Maxwellian ones as with a surplus as well as with a shortage in the Maxwellian
distribution function tail. It is shown that there are present for the
considered cases both collisionless damping and also non-damping electron waves
even in the case of non-Maxwellian distribution function.",0708.0748v5
2007-08-14,Preliminary Results on Vibration Damping Properties of Nanoscale-Reinforced Composite Materials,"The focus in this paper is an analysis of existing state of the arts directed
toward the development of the next generation of vibration damping systems. The
research work concentrates on an investigation related to
nanoparticles/fibres/tubes-reinforced materials and coatings dynamic
characterization and modeling of the fundamental phenomena that control
relationships between structure and damping/mechanical properties of the
materials. We simulated composite materials using finite element and mesh free
methods, using a hollow shell representation of the individual nanotube/fiber.
Results of the research work will provide a platform for the development of
nanoparticle-reinforced damping materials that are light-weight, vibration and
shock resistant. The outcome of the research work is expected to have
wide-ranging technical benefits with direct relevance to industry in areas of
transportation (aerospace, automotive, rail), electronics and civil
infrastructure development.",0708.1821v1
2007-08-18,Non-Riemannian geometrical asymmetrical damping stresses on the Lagrange instability of shear flows,"It is shown that the physical interpretation of Elie Cartan three-dimensional
space torsion as couple asymmetric stress, has the effect of damping,
previously Riemannian unstable Couette planar shear flow, leading to stability
of the flow in the Lagrangean sense. Actually, since the flow speed is
inversely proportional to torsion, it has the effect of causing a damping in
the planar flow atenuating the instability effect. In this sense we may say
that Cartan torsion induces shear viscous asymmetric stresses in the fluid,
which are able to damp the instability of the flow. The stability of the flow
is computed from the sectional curvature in non-Riemannian three-dimensional
manifold. Marginal stability is asssumed by making the sectional non-Riemannian
curvature zero, which allows us to determine the speeds of flows able to induce
this stability. The ideas discussed here show that torsion plays the
geometrical role of magnetic field in hydromagnetic instability of Couette
flows recently investigated by Bonnano and Urpin (PRE, (2007,in press) can be
extended and applied to plastic flows with microstructure defects. Recently
Riemannian asymmetric stresses in magnetohydrodynamics (MHD) have been
considered by Billig (2004).",0708.2467v1
2007-12-07,State transition of a non-Ohmic damping system in a corrugated plane,"Anomalous transport of a particle subjected to non-Ohmic damping of the power
$\delta$ in a tilted periodic potential is investigated via Monte Carlo
simulation of generalized Langevin equation. It is found that the system
exhibits two relative motion modes: the locking state and the running state.
Under the surrounding of sub-Ohmic damping ($0<\delta<1$), the particle should
transfer into a running state from a locking state only when local minima of
the potential vanish; hence the particle occurs a synchronization oscillation
in its mean displacement and mean square displacement (MSD). In particular, the
two motion modes are allowed to coexist in the case of super-Ohmic damping
($1<\delta<2$) for moderate driving forces, namely, where exists double centers
in the velocity distribution. This induces the particle having faster
diffusion, i.e., its MSD reads $<\Delta x^2(t)> = 2D^{(\delta)}_{eff}
t^{\delta_{eff}}$. Our result shows that the effective power index
$\delta_{\textmd{eff}}$ can be enhanced and is a nonmonotonic function of the
temperature and the driving force. The mixture effect of the two motion modes
also leads to a breakdown of hysteresis loop of the mobility.",0712.1070v1
2007-12-25,The damped Pinney equation and its applications to dissipative quantum mechanics,"The work considers the damped Pinney equation, defined as the model arising
when a linear in velocity damping term is included in the Pinney equation. In
the general case the resulting equation does not admit Lie point symmetries or
is reducible to a simpler form by any obvious coordinate transformation. In
this context the method of Kuzmak-Luke is applied to derive a perturbation
solution, for weak damping and slow time-dependence of the frequency function.
The perturbative and numerical solutions are shown to be in good agreement. The
results are applied to examine the time-evolution of Gaussian shaped
wave-functions in the Kostin formulation of dissipative quantum mechanics.",0712.4083v3
2008-01-01,Non-linear equations for electron waves in Maxwellian low-collision ion-electron plasmas,"The before described general principles and methodology of calculating
electron wave propagation in homogeneous isotropic half-infinity slab of
Maxwellian plasma with indefinite but in principal value sense taken integrals
in characteristic equations, and the use of 2D Laplace transform method are
applied to an evaluation of collision damping decrements of plane electron
longitudinal and transverse waves. Damping decrement tends to infinity when the
wave frequency tends to electron Langmuir frequency from above values. We
considered recurrent relations for amplitudes of the overtones which form in
their sum the all solution of the plasma wave non-linear equations including
collision damping and quadratic (non-linear) terms. Collisionless damping at
frequencies more the Langmuir one is possible only in non-Maxwellian plasmas.",0801.0286v2
2008-02-22,Radiative Damping and Functional Differential Equations,"We propose a general technique to solve the classical many-body problem with
radiative damping. We modify the short-distance structure of Maxwell
electrodynamics. This allows us to avoid runaway solutions as if we had a
covariant model of extended particles. The resulting equations of motion are
functional differential equations (FDEs) rather than ordinary differential
equations. Using recently developed numerical techniques for stiff FDEs, we
solve these equations for the one-body central force problem with radiative
damping with a view to benchmark our new approach. Our results indicate that
locally the magnitude of radiation damping may be well approximated by the
standard third-order expression but the global properties of our solutions are
dramatically different. We comment on the two body problem and applications to
quantum field theory and quantum mechanics.",0802.3390v2
2008-04-24,Analytic approximate seismology of transversely oscillating coronal loops,"We present an analytic approximate seismic inversion scheme for damped
transverse coronal loop oscillations based on the thin tube and thin boundary
approximation for computing the period and the damping time. Asymptotic
expressions for the period and damping rate are used to illustrate the process
of seismological inversion in a simple and easy to follow manner. The inversion
procedure is formulated in terms of two simple functions, which are given by
simple closed expressions. The analytic seismic inversion shows that an
infinite amount of 1-dimensional equilibrium models can reproduce the observed
periods and damping times. It predicts a specific range of allowable values for
the Alfven travel time and lower bounds for the density contrast and the
inhomogeneity length scale. When the results of the present analytic seismic
inversion are compared with those of a previous numerical inversion, excellent
agreement is found up to the point that the analytic seismic inversion emerges
as a tool for validating results of numerical inversions. Actually it helped us
to identify and correct inaccuracies in a previous numerical investigation.",0804.3877v1
2008-10-21,On Wigner functions and a damped star product in dissipative phase-space quantum mechanics,"Dito and Turrubiates recently introduced an interesting model of the
dissipative quantum mechanics of a damped harmonic oscillator in phase space.
Its key ingredient is a non-Hermitian deformation of the Moyal star product
with the damping constant as deformation parameter. We compare the
Dito-Turrubiates scheme with phase-space quantum mechanics (or deformation
quantization) based on other star products, and extend it to incorporate Wigner
functions. The deformed (or damped) star product is related to a complex
Hamiltonian, and so necessitates a modified equation of motion involving
complex conjugation. We find that with this change the Wigner function
satisfies the classical equation of motion. This seems appropriate since
non-dissipative systems with quadratic Hamiltonians share this property.",0810.3893v1
2008-12-17,Origin of intrinsic Gilbert damping,"The damping of magnetization, represented by the rate at which it relaxes to
equilibrium, is successfully modeled as a phenomenological extension in the
Landau-Lifschitz-Gilbert equation. This is the damping torque term known as
Gilbert damping and its direction is given by the vector product of the
magnetization and its time derivative. Here we derive the Gilbert term from
first principles by a non-relativistic expansion of the Dirac equation. We find
that the Gilbert term arises when one calculates the time evolution of the spin
observable in the presence of the full spin-orbital coupling terms, while
recognizing the relationship between the curl of the electric field and the
time varying magnetic induction.",0812.3184v2
2009-01-08,Grand-mother clocks and quiet lasers,"Galileo noted in the 16th century that the period of oscillation of a
pendulum is almost independent of the amplitude. However, such a pendulum is
damped by air friction. The latter may be viewed as resulting from air
molecules getting in contact with the pendulum. It follows that air friction,
not only damps the oscillation, but also introduces randomness. In the
so-called ``grand-mother'' clock, discovered by Huygens in the 18th century,
damping is compensated for, on the average, by an escapement mechanism driven
by a falling weight. The purpose of this paper is to show that such a clock is,
in its idealized form, a quiet oscillator. By ``quiet'' we mean that in spite
of the randomness introduced by damping, the dissipated power (viewed as the
oscillator output) does not fluctuate slowly. Comparison is made with quiet
laser oscillators discovered theoretically in 1984. Because the input power
does not fluctuate in both the mechanical oscillator and the quiet laser
oscillator, the output power does not fluctuate at small Fourier frequencies,
irrespectively of the detailed mechanisms involved.",0901.0983v1
2009-01-15,Interaction of fast charged projectiles with two-dimensional electron gas: Interaction and disorder effects,"The results of a theoretical investigation on the stopping power of ions
moving in a disordered two-dimensional degenerate electron gas are presented.
The stopping power for an ion is calculated employing linear response theory
using the dielectric function approach. The disorder, which leads to a damping
of plasmons and quasiparticles in the electron gas, is taken into account
through a relaxation time approximation in the linear response function. The
stopping power for an ion is calculated in both the low- and high-velocity
limits. In order to highlight the effects of damping we present a comparison of
our analytical and numerical results, in the case of point-like ions, obtained
for a non-zero damping with those for a vanishing damping. It is shown that the
equipartition sum rule first formulated by Lindhard and Winther for
three-dimensional degenerate electron gas does not necessarily hold in
two-dimensions. We have generalized this rule introducing an effective
dielectric function. In addition some new results for two-dimensional
interacting electron gas have been obtained. In this case the
exchange-correlation interactions of electrons are considered via
local-field-corrected dielectric function.",0901.2249v1
2009-02-01,Non-Markovian Analysis of the Phase Damped Jaynes-Cummings Model in the Presence of a Classical Homogeneous Gravitational Field,"In this paper, the non-Markovian dissipative dynamics of the phase damped
Jaynes-Cummings model in the presence of a classical homogeneous gravitational
field will be analyzed. The model consists of a moving two-level atom
simultaneously exposed to the gravitational field and a single-mode traveling
radiation field in the presence of a non-Markovian phase damping mechanism.
First, the non-Markovian master equation for the reduced density operator of
the system in terms of a Hamiltonian describing the atom-field interaction in
the presence of a homogeneous gravitational field will be presented. Then, the
super-operator technique will be generalized and an exact solution of the
non-Markovian master equation will be obtained. Assuming that initially the
radiation field is prepared in a Glauber coherent state and the two-level atom
is in the excited state, the non-Markovian effects on the temporal evolution of
collapses and revivals of the atomic population inversion and photon counting
statistics of the radiation field in the presence of both the phase damping and
a homogeneous gravitational field will be investigated.",0902.0114v1
2009-05-04,Models of Damped Oscillators in Quantum Mechanics,"We consider several models of the damped oscillators in nonrelativistic
quantum mechanics in a framework of a general approach to the dynamics of the
time-dependent Schroedinger equation with variable quadratic Hamiltonians. The
Green functions are explicitly found in terms of elementary functions and the
corresponding gauge transformations are discussed. The factorization technique
is applied to the case of a shifted harmonic oscillator. The time-evolution of
the expectation values of the energy related operators is determined for two
models of the quantum damped oscillators under consideration. The classical
equations of motion for the damped oscillations are derived for the
corresponding expectation values of the position operator.",0905.0507v6
2009-05-28,Resonant Nonlinear Damping of Quantized Spin Waves in Ferromagnetic Nanowires,"We use spin torque ferromagnetic resonance to measure the spectral properties
of dipole-exchange spin waves in permalloy nanowires. Our measurements reveal
that geometric confinement has a profound effect on the damping of spin waves
in the nanowire geometry. The damping parameter of the lowest-energy quantized
spin wave mode depends on applied magnetic field in a resonant way and exhibits
a maximum at a field that increases with decreasing nanowire width. This
enhancement of damping originates from a nonlinear resonant three-magnon
confluence process allowed at a particular bias field value determined by
quantization of the spin wave spectrum in the nanowire geometry.",0905.4699v2
2009-06-01,Effect of Decoherence in Ekert-Protocol,"We have examined the effect of the decoherence in the Ekert91 quantum
cryptographic protocol. In order to explore this issue we have introduced two
major decoherences, the depolarizing channel and the generalized amplitude
damping, between the singlet source and one of the legitimate users. It is
shown that the depolarizing channel disentangles the quantum channel more
easily than the generalized amplitude damping. This fact indicates that the
Ekert protocol is more robust to the generalized amplitude damping. We also
have computed the Bell inequality to check the robustness or weakness of the
Ekert91 protocol. Computation of the Bell inequality also confirms the
robustness of the Ekert91 protocol to the generalized amplitude damping
compared to the depolarizing channel.",0906.0233v1
2009-08-05,Surface plasmon lifetime in metal nanoshells,"The lifetime of localized surface plasmon plays an important role in many
aspects of plasmonics and its applications. In small metal nanostructures, the
dominant mechanism restricting plasmon lifetime is size-dependent Landau
damping. We performed quantum-mechanical calculations of Landau damping for the
bright surface plasmon mode in a metal nanoshell. In contrast to the
conventional model based on the electron surface scattering, we found that the
damping rate decreases as the nanoshell thickness is reduced. The origin of
this behavior is traced to the spatial distribution of plasmon local field
inside the metal shell. We also found that, due to interference of electron
scattering amplitudes from nanoshell's two metal surfaces, the damping rate
exhibits pronounced quantum beats with changing shell thickness.",0908.0647v3
2009-08-12,Coarse Grained Simulations of a Small Peptide: Effects of Finite Damping and Hydrodynamic Interactions,"In the coarse grained Brownian Dynamics simulation method the many solvent
molecules are replaced by random thermal kicks and an effective friction acting
on the particles of interest. For Brownian Dynamics the friction has to be so
strong that the particles' velocities are damped much faster than the duration
of an integration timestep. Here we show that this conceptual limit can be
dropped with an analytic integration of the equations of damped motion. In the
resulting Langevin integration scheme our recently proposed approximate form of
the hydrodynamic interactions between the particles can be incorparated
conveniently, leading to a fast multi-particle propagation scheme, which
captures more of the short-time and short-range solvent effects than standard
BD. Comparing the dynamics of a bead-spring model of a short peptide, we
recommend to run simulations of small biological molecules with the Langevin
type finite damping and to include the hydrodynamic interactions.",0908.1685v1
2009-09-01,Quantum Stackelberg duopoly in the presence of correlated noise,"We study the influence of entanglement and correlated noise using correlated
amplitude damping, depolarizing and phase damping channels on the quantum
Stackelberg duopoly. Our investigations show that under the action of amplitude
damping channel a critical point exists for unentangled initial state as well,
at which firms get equal payoffs. The game becomes a follower advantage game
when the channel is highly decohered. Two critical points corresponding to two
values of the entanglement angle are found in the presence of correlated noise.
Within the range of these limits of entanglement angle, the game is follower
advantage game. In case of depolarizing channel, the payoffs of the two firms
are strongly influenced by the memory parameter. The presence of quantum memory
ensures the existence of Nash equilibrium for the entire range of decoherence
and entanglement parameters for both the channels. A local maximum in the
payoffs is observed which vanishes as the channel correlation increases.
Moreover, under the influence of depolarizing channel, the game is always a
leader advantage game. Furthermore, it is seen that phase damping channel does
not effect the outcome of the game.",0909.0063v2
2009-09-04,Second sound dipole mode in a partially Bose-Einstein condensed gas,"We study the second sound dipole mode in a partially Bose-Einstein condensed
gas. This mode is excited by spatially separating and releasing the
center-of-mass of the Bose-Einstein condensate (BEC) with respect to the
thermal cloud, after which the equilibration is observed. The oscillation
frequency and the damping rate of this mode is studied for different harmonic
confinements and temperatures. The measured damping rates close to the
collisionless regime are found to be in good agreement with Landau damping. For
increasing hydrodynamicity of the cloud we observe an increase of the damping.",0909.0886v1
2010-02-12,Features of ion acoustic waves in collisional plasmas,"The effects of friction on the ion acoustic (IA) wave in fully and partially
ionized plasmas are studied. In a quasi-neutral electron-ion plasma the
friction between the two species cancels out exactly and the wave propagates
without any damping. If the Poisson equation is used instead of the
quasi-neutrality, however, the IA wave is damped and the damping is dispersive.
In a partially ionized plasma, the collisions with the neutrals modify the IA
wave beyond recognition. For a low density of neutrals the mode is damped. Upon
increasing the neutral density, the mode becomes first evanescent and then
reappears for a still larger number of neutrals. A similar behavior is obtained
by varying the mode wave-length. The explanation for this behavior is given. In
an inhomogeneous plasma placed in an external magnetic field, and for
magnetized electrons and un-magnetized ions, the IA mode propagates in any
direction and in this case the collisions make it growing on the account of the
energy stored in the density gradient. The growth rate is angle dependent. A
comparison with the collision-less kinetic density gradient driven IA
instability is also given.",1002.2502v1
2010-02-18,Damping mechanisms for oscillations in solar prominences,"Small amplitude oscillations are a commonly observed feature in
prominences/filaments. These oscillations appear to be of local nature, are
associated to the fine structure of prominence plasmas, and simultaneous flows
and counterflows are also present. The existing observational evidence reveals
that small amplitude oscillations, after excited, are damped in short spatial
and temporal scales by some as yet not well determined physical mechanism(s).
Commonly, these oscillations have been interpreted in terms of linear
magnetohydrodynamic (MHD) waves, and this paper reviews the theoretical damping
mechanisms that have been recently put forward in order to explain the observed
attenuation scales. These mechanisms include thermal effects, through
non-adiabatic processes, mass flows, resonant damping in non-uniform media, and
partial ionization effects. The relevance of each mechanism is assessed by
comparing the spatial and time scales produced by each of them with those
obtained from observations. Also, the application of the latest theoretical
results to perform prominence seismology is discussed, aiming to determine
physical parameters in prominence plasmas that are difficult to measure by
direct means.",1002.3489v2
2010-03-07,Theory of plasmon decay in dense plasmas and warm dense matter,"The decay of the Langmuir waves in dense plasmas is not accurately predicted
by the prevalent Landau damping theory. A dielectric function theory is
introduced, predicting much higher damping than the Landau damping theory. This
strong damping is in better agreement with the experimentally observed data in
metals. It is shown that the strong plasmon decay leads to the existence of a
parameter regime where the backward Raman scattering is unstable while the
forward Raman scattering is stable. This regime may be used to create intense
x-ray pulses, by means of the the backward Raman compression. The optimal pulse
duration and intensity is estimated.",1003.1523v2
2010-03-16,Justification of the symmetric damping model of the dynamical Casimir effect in a cavity with a semiconductor mirror,"A ""microscopic"" justification of the ""symmetric damping"" model of a quantum
oscillator with time-dependent frequency and time-dependent damping is given.
This model is used to predict results of experiments on simulating the
dynamical Casimir effect in a cavity with a photo-excited semiconductor mirror.
It is shown that the most general bilinear time-dependent coupling of a
selected oscillator (field mode) to a bath of harmonic oscillators results in
two equal friction coefficients for the both quadratures, provided all the
coupling coefficients are proportional to a single arbitrary function of time
whose duration is much shorter than the periods of all oscillators. The choice
of coupling in the rotating wave approximation form leads to the ""mimimum
noise"" model of the quantum damped oscillator, introduced earlier in a pure
phenomenological way.",1003.3061v2
2010-04-12,Dissipative Transport of a Bose-Einstein Condensate,"We investigate the effects of impurities, either correlated disorder or a
single Gaussian defect, on the collective dipole motion of a Bose-Einstein
condensate of $^7$Li in an optical trap. We find that this motion is damped at
a rate dependent on the impurity strength, condensate center-of-mass velocity,
and interatomic interactions. Damping in the Thomas-Fermi regime depends
universally on the disordered potential strength scaled to the condensate
chemical potential and the condensate velocity scaled to the peak speed of
sound. The damping rate is comparatively small in the weakly interacting
regime, and the damping in this case is accompanied by strong condensate
fragmentation. \textit{In situ} and time-of-flight images of the atomic cloud
provide evidence that this fragmentation is driven by dark soliton formation.",1004.1891v2
2010-07-07,Observational evidence of resonantly damped propagating kink waves in the solar corona,"In this Letter we establish clear evidence for the resonant absorption
damping mechanism by analyzing observational data from the novel Coronal
Multi-Channel Polarimeter (CoMP). This instrument has established that in the
solar corona there are ubiquitous propagating low amplitude ($\approx$1 km
s$^{-1}$) Alfv\'{e}nic waves with a wide range of frequencies. Realistically
interpreting these waves as the kink mode from magnetohydrodynamic (MHD) wave
theory, they should exhibit a frequency dependent damping length due to
resonant absorption, governed by the TGV relation showing that transversal
plasma inhomogeneity in coronal magnetic flux tubes causes them to act as
natural low-pass filters. It is found that observed frequency dependence on
damping length (up to about 8 mHz) can be explained by the kink wave
interpretation and furthermore, the spatially averaged equilibrium parameter
describing the length scale of transverse plasma density inhomogeneity over a
system of coronal loops is consistent with the range of values estimated from
TRACE observations of standing kink modes.",1007.1080v1
2010-07-12,Variable damping and coherence in a high-density magnon gas,"We report on the fast relaxation behavior of a high-density magnon gas
created by a parametric amplification process. The magnon gas is probed using
the technique of spin-wave packet recovery by parallel parametric pumping.
Experimental results show a damping behavior which is in disagreement with both
the standard model of exponential decay and with earlier observations of
non-linear damping. In particular, the inherent magnon damping is found to
depend upon the presence of the parametric pumping field. A phenomenological
model which accounts for the dephasing of the earlier injected magnons is in
good agreement with the experimental data.",1007.1895v3
2010-07-21,A low-power circuit for piezoelectric vibration control by synchronized switching on voltage sources,"In the paper, a vibration damping system powered by harvested energy with
implementation of the so-called SSDV (synchronized switch damping on voltage
source) technique is designed and investigated. In the semi-passive approach,
the piezoelectric element is intermittently switched from open-circuit to
specific impedance synchronously with the structural vibration. Due to this
switching procedure, a phase difference appears between the strain induced by
vibration and the resulting voltage, thus creating energy dissipation. By
supplying the energy collected from the piezoelectric materials to the
switching circuit, a new low-power device using the SSDV technique is proposed.
Compared with the original self-powered SSDI (synchronized switch damping on
inductor), such a device can significantly improve its performance of vibration
control. Its effectiveness in the single-mode resonant damping of a composite
beam is validated by the experimental results.",1007.3596v1
2010-10-24,Long-time dynamics in plate models with strong nonlinear damping,"We study long-time dynamics of a class of abstract second order in time
evolution equations in a Hilbert space with the damping term depending both on
displacement and velocity. This damping represents the nonlinear strong
dissipation phenomenon perturbed with relatively compact terms. Our main result
states the existence of a compact finite dimensional attractor. We study
properties of this attractor. We also establish the existence of a fractal
exponential attractor and give the conditions that guarantee the existence of a
finite number of determining functionals. In the case when the set of
equilibria is finite and hyperbolic we show that every trajectory is attracted
by some equilibrium with exponential rate. Our arguments involve a recently
developed method based on the ""compensated"" compactness and quasi-stability
estimates. As an application we consider the nonlinear Kirchhoff, Karman and
Berger plate models with different types of boundary conditions and strong
damping terms. Our results can be also applied to the nonlinear wave equations.",1010.4991v1
2010-11-05,"Effects of Turbulence, Eccentricity Damping, and Migration Rate on the Capture of Planets into Mean Motion Resonance","Pairs of migrating extrasolar planets often lock into mean motion resonance
as they drift inward. This paper studies the convergent migration of giant
planets (driven by a circumstellar disk) and determines the probability that
they are captured into mean motion resonance. The probability that such planets
enter resonance depends on the type of resonance, the migration rate, the
eccentricity damping rate, and the amplitude of the turbulent fluctuations.
This problem is studied both through direct integrations of the full 3-body
problem, and via semi-analytic model equations. In general, the probability of
resonance decreases with increasing migration rate, and with increasing levels
of turbulence, but increases with eccentricity damping. Previous work has shown
that the distributions of orbital elements (eccentricity and semimajor axis)
for observed extrasolar planets can be reproduced by migration models with
multiple planets. However, these results depend on resonance locking, and this
study shows that entry into -- and maintenance of -- mean motion resonance
depends sensitively on migration rate, eccentricity damping, and turbulence.",1011.1486v1
2010-11-21,Quasi-normal frequencies: Semi-analytic results for highly damped modes,"Black hole highly-damped quasi-normal frequencies (QNFs) are very often of
the form (offset)} + i n (gap). We have investigated the genericity of this
phenomenon for the Schwarzschild--deSitter (SdS) black hole by considering a
model potential that is piecewise Eckart (piecewise Poeschl-Teller), and
developing an analytic ``quantization condition'' for the highly-damped
quasi-normal frequencies. We find that the (offset) + i n(gap) behaviour is
common but not universal, with the controlling feature being whether or not the
ratio of the surface gravities is a rational number. We furthermore observed
that the relation between rational ratios of surface gravities and periodicity
of QNFs is very generic, and also occurs within different analytic approaches
applied to various types of black hole spacetimes. These observations are of
direct relevance to any physical situation where highly-damped quasi-normal
modes are important.",1011.4634v1
2011-03-08,Application of Explicit Symplectic Algorithms to Integration of Damping Oscillators,"In this paper an approach is outlined. With this approach some explicit
algorithms can be applied to solve the initial value problem of $n-$dimensional
damped oscillators. This approach is based upon following structure: for any
non-conservative classical mechanical system and arbitrary initial conditions,
there exists a conservative system; both systems share one and only one common
phase curve; and, the value of the Hamiltonian of the conservative system is,
up to an additive constant, equal to the total energy of the non-conservative
system on the aforementioned phase curve, the constant depending on the initial
conditions. A key way applying explicit symplectic algorithms to damping
oscillators is that by the Newton-Laplace principle the nonconservative force
can be reasonably assumed to be equal to a function of a component of
generalized coordinates $q_i$ along a phase curve, such that the damping force
can be represented as a function analogous to an elastic restoring force
numerically in advance. Two numerical examples are given to demonstrate the
good characteristics of the algorithms.",1103.1455v1
2011-03-09,Nonlinear damping in mechanical resonators based on graphene and carbon nanotubes,"Carbon nanotubes and graphene allow fabricating outstanding nanomechanical
resonators. They hold promise for various scientific and technological
applications, including sensing of mass, force, and charge, as well as the
study of quantum phenomena at the mesoscopic scale. Here, we have discovered
that the dynamics of nanotube and graphene resonators is in fact highly exotic.
We propose an unprecedented scenario where mechanical dissipation is entirely
determined by nonlinear damping. As a striking consequence, the quality factor
Q strongly depends on the amplitude of the motion. This scenario is radically
different from that of other resonators, whose dissipation is dominated by a
linear damping term. We believe that the difference stems from the reduced
dimensionality of carbon nanotubes and graphene. Besides, we exploit the
nonlinear nature of the damping to improve the figure of merit of
nanotube/graphene resonators.",1103.1788v1
2011-05-03,Entanglement in a Bipartite Gaussian State,"To examine the loss of entanglement in a two-particle Gaussian system, we
couple it to an environment and use the Non-Rotating Wave master equation to
study the system's dynamics. We also present a derivation of this equation. We
consider two different types of evolution. Under free evolution we find that
entanglement is lost quickly between the particles. When a harmonic potential
is added between the particles, two very different behaviours can be observed,
namely in the over and under-damped cases respectively, where the strength of
the damping is determined by how large the coupling to the bath is with respect
to the frequency of the potential. In the over-damped case, we find that the
entanglement vanishes at even shorter times than it does in the free evolution.
In the (very) under-damped case, we observe that the entanglement does not
vanish. Instead it oscillates towards a stable value.",1105.0564v1
2011-06-15,Plasma damping effects on the radiative energy loss of relativistic particles,"The energy loss of a relativistic charge undergoing multiple scatterings
while traversing an infinite, polarizable and absorptive plasma is
investigated. Polarization and damping mechanisms in the medium are
phenomenologically modelled by a complex index of refraction. Apart from the
known Ter-Mikaelian effect related to the dielectric polarization of matter, we
find an additional, substantial reduction of the energy loss due to damping of
radiation. The observed effect is more prominent for larger damping and/or
larger energy of the charge. A conceivable analog of this phenomenon in QCD
could influence the study of jet quenching phenomena in ultra-relativistic
heavy-ion collisions at RHIC and LHC.",1106.2856v3
2011-09-12,Reduction of compressibility and parallel transfer by Landau damping in turbulent magnetized plasmas,"Three-dimensional numerical simulations of decaying turbulence in a
magnetized plasma are performed using a so-called FLR-Landau fluid model which
incorporates linear Landau damping and finite Larmor radius (FLR) corrections.
It is shown that compared to simulations of compressible Hall-MHD, linear
Landau damping is responsible for significant damping of magnetosonic waves,
which is consistent with the linear kinetic theory. Compressibility of the
fluid and parallel energy cascade along the ambient magnetic field are also
significantly inhibited when the beta parameter is not too small. In contrast
with Hall-MHD, the FLR-Landau fluid model can therefore correctly describe
turbulence in collisionless plasmas such as the solar wind, providing an
interpretation for its nearly incompressible behavior.",1109.2636v1
2011-09-24,Existence of weak solutions for the generalized Navier-Stokes equations with damping,"In this work we consider the generalized Navier-Stoke equations with the
presence of a damping term in the momentum equation. % The problem studied here
derives from the set of equations which govern the isothermal flow of
incompressible, homogeneous and non-Newtonian fluids. % For the generalized
Navier-Stokes problem with damping, we prove the existence of weak solutions by
using regularization techniques, the theory of monotone operators and
compactness arguments together with the local decomposition of the pressure and
the Lipschitz-truncation method. The existence result proved here holds for any
$q>\frac{2N}{N+2}$ and any $\sigma>1$, where $q$ is the exponent of the
diffusion term and $\sigma$ is the exponent which characterizes the damping
term.",1109.5217v1
2011-12-20,Dynamics of DNA breathing in the Peyrard-Bishop model with damping and external force,"The impact of damping effect and external forces to the DNA breathing is
investigated within the Peyrard-Bishop model. In in the continuum limit, the
dynamics of the breathing of DNA is described by the forced-damped nonlinear
Schrodinger equation and studied by means of variational method. The analytical
solutions are obtained for special cases. It is shown that the breather
propagation is decelerated in the presence of damping factor without the
external force, while the envelope velocity and the amplitude increase
significantly with the presence of external force. It is particularly found
that the higher harmonic terms are enhanced when the periodic force is applied.
It is finally argued that the external force accelerates the DNA breathing.",1112.4715v1
2012-02-22,Radiation Damping in the Photoionization of Fe^{14+},"A theoretical investigation of photoabsorption and photoionization of
Fe^{14+} extending beyond an earlier frame transformation R-matrix
implementation is performed using a fully-correlated, Breit-Pauli R-matrix
formulation including both fine-structure splitting of strongly-bound
resonances and radiation damping. The radiation damping of $2p\rightarrow nd$
resonances gives rise to a resonant photoionization cross section that is
significantly lower than the total photoabsorption cross section. Furthermore,
the radiation-damped photoionization cross section is found to be in good
agreement with recent experimental results once a global shift in energy of
$\approx -3.5$ eV is applied. These findings have important implications.
Firstly, the presently available synchrotron experimental data are applicable
only to photoionization processes and not to photoabsorption; the latter is
required in opacity calculations. Secondly, our computed cross section, for
which the L-shell ionization threshold is aligned with the NIST value, shows a
series of $2p \rightarrow nd$ Rydberg resonances that are uniformly 3-4 eV
higher in energy than the corresponding experimental profiles, indicating that
the L-shell threshold energy values currently recommended by NIST are likely in
error.",1202.4800v1
2012-02-29,Present status of development of damping ring extraction kicker system for CLIC,"The CLIC damping rings will produce ultra-low emittance beam, with high bunch
charge, necessary for the luminosity performance of the collider. To limit the
beam emittance blow-up due to oscillations, the pulse power modulators for the
damping ring kickers must provide extremely flat, high-voltage pulses:
specifications call for a 160 ns duration and a flattop of 12.5 kV, 250 A, with
a combined ripple and droop of not more than \pm0.02 %. The stripline design is
also extremely challenging: the field for the damping ring kicker system must
be homogenous to within \pm0.01 % over a 1 mm radius, and low beam coupling
impedance is required. The solid-state modulator, the inductive adder, is a
very promising approach to meeting the demanding specifications for the field
pulse ripple and droop. This paper describes the initial design of the
inductive adder and the striplines of the kicker system.",1202.6527v1
2012-06-20,Metadamping: An emergent phenomenon in dissipative metamaterials,"We theoretically demonstrate the concept of metadamping in dissipative
metamaterials. We consider an infinite mass-spring chain with repeated local
resonators and a statically equivalent periodic chain whose wave propagation
characteristics are based on Bragg scattering. For each system we introduce
identical viscous damping (dashpot) elements and compare the damping ratio
associated with all Bloch modes. We find that the locally resonant metamaterial
exhibits higher dissipation overall which indicates a damping emergence
phenomena due to the presence of local resonance. We conclude our investigation
by quantifying the degree of emergent damping as a function of the long-wave
speed of sound in the medium or the static stiffness.",1206.4577v2
2012-07-12,Spin Damping in an RF Atomic Magnetometer,"Under negative feedback, the quality factor Q of a radio-frequency
magnetometer can be decreased by more than two orders of magnitude, so that any
initial perturbation of the polarized spin system can be rapidly damped,
preparing the magnetometer for detection of the desired signal. We find that
noise is also suppressed under such spin-damping, with a characteristic
spectral response corresponding to the type of noise; therefore magnetic,
photon-shot, and spin-projection noise can be measured distinctly. While the
suppression of resonant photon-shot noise implies the closed-loop production of
polarization-squeezed light, the suppression of resonant spin-projection noise
does not imply spin-squeezing, rather simply the broadening of the noise
spectrum with Q. Furthermore, the application of spin-damping during
phase-sensitive detection suppresses both signal and noise in such a way as to
increase the sensitivity bandwidth. We demonstrate a three-fold increase in the
magnetometer's bandwidth while maintaining 0.3 fT/\surdHz sensitivity.",1207.2842v1
2012-07-12,Damping of phase fluctuations in superfluid Bose gases,"Using Popov's hydrodynamic approach we derive an effective Euclidean action
for the long-wavelength phase fluctuations of superfluid Bose gases in D
dimensions. We then use this action to calculate the damping of phase
fluctuations at zero temperature as a function of D. For D >1 and wavevectors |
k | << 2 mc (where m is the mass of the bosons and c is the sound velocity) we
find that the damping in units of the phonon energy E_k = c | k | is to leading
order gamma_k / E_k = A_D (k_0^D / 2 pi rho) (| k | / k_0)^{2 D -2}, where rho
is the boson density and k_0 =2 mc is the inverse healing length. For D -> 1
the numerical coefficient A_D vanishes and the damping is proportional to an
additional power of |k | /k_0; a self-consistent calculation yields in this
case gamma_k / E_k = 1.32 (k_0 / 2 pi rho)^{1/2} |k | / k_0. In one dimension,
we also calculate the entire spectral function of phase fluctuations.",1207.3002v3
2012-08-27,The properties of non-thermal X-ray filaments in young supernova remnants,"Context. Young supernova remnants (SNRs) exhibit narrow filaments of
non-thermal X-ray emission whose widths can be limited either by electron
energy losses or damping of the magnetic field. Aims. We want to investigate
whether or not different models of these filaments can be observationally
tested. Methods. Using observational parameters of four historical remnants, we
calculate the filament profiles and compare the spectra of the filaments with
those of the total non-thermal emission. For that purpose, we solve an
one-dimensional stationary transport equation for the isotropic differential
number density of the electrons. Results. We find that the difference between
the spectra of filament and total non-thermal emission above 1 keV is more
pronounced in the damping model than in the energy-loss model. Conclusions. A
considerable damping of the magnetic field can result in an observable
difference between the spectra of filament and total non-thermal emission, thus
potentially permitting an observational discrimination between the energy-loss
model and the damping model of the X-ray filaments.",1208.5322v1
2012-09-10,Mid-infrared plasmons in scaled graphene nanostructures,"Plasmonics takes advantage of the collective response of electrons to
electromagnetic waves, enabling dramatic scaling of optical devices beyond the
diffraction limit. Here, we demonstrate the mid-infrared (4 to 15 microns)
plasmons in deeply scaled graphene nanostructures down to 50 nm, more than 100
times smaller than the on-resonance light wavelength in free space. We reveal,
for the first time, the crucial damping channels of graphene plasmons via its
intrinsic optical phonons and scattering from the edges. A plasmon lifetime of
20 femto-seconds and smaller is observed, when damping through the emission of
an optical phonon is allowed. Furthermore, the surface polar phonons in SiO2
substrate underneath the graphene nanostructures lead to a significantly
modified plasmon dispersion and damping, in contrast to a non-polar
diamond-like-carbon (DLC) substrate. Much reduced damping is realized when the
plasmon resonance frequencies are close to the polar phonon frequencies. Our
study paves the way for applications of graphene in plasmonic waveguides,
modulators and detectors in an unprecedentedly broad wavelength range from
sub-terahertz to mid-infrared.",1209.1984v1
2012-11-05,No asymptotically highly damped quasi-normal modes without horizons?,"We explore the question of what happens with the asymptotically highly damped
quasi-normal modes ($\ell$ fixed, $|\omega_{I}|\to\infty$) when the underlying
spacetime has no event horizons. We consider the characteristic oscillations of
a scalar field in a large class of asymptotically flat spherically symmetric
static spacetimes without (absolute) horizons, such that the class accommodates
the cases that are known to be of some sort of physical interest. The question
of the asymptotic quasi-normal modes in such spacetimes is relevant to
elucidate the connection between the behavior of the asymptotic quasi-normal
modes and the quantum properties of event horizons, as put forward in some
recent important conjectures. We prove for a large class of asymptotically flat
spacetimes without horizons that the scalar field asymptotically highly damped
modes do not exist. This provides in our view additional evidence that there is
indeed a close link between the asymptotically highly damped modes and the
existence of spacetime horizons (and their properties).",1211.1046v2
2012-11-21,Chaotic saddles in nonlinear modulational interactions in a plasma,"A nonlinear model of modulational processes in the subsonic regime involving
a linearly unstable wave and two linearly damped waves with different damping
rates in a plasma is studied numerically. We compute the maximum Lyapunov
exponent as a function of the damping rates in a two-parameter space, and
identify shrimp-shaped self-similar structures in the parameter space. By
varying the damping rate of the low-frequency wave, we construct bifurcation
diagrams and focus on a saddle-node bifurcation and an interior crisis
associated with a periodic window. We detect chaotic saddles and their stable
and unstable manifolds, and demonstrate how the connection between two chaotic
saddles via coupling unstable periodic orbits can result in a crisis-induced
intermittency. The relevance of this work for the understanding of modulational
processes observed in plasmas and fluids is discussed.",1211.5070v1
2012-12-18,Thermal activation at moderate-to-high and high damping: finite barrier effects and force spectroscopy,"We study the thermal escape problem in the moderate-to-high and high damping
regime of a system with a parabolic barrier. We present a formula that matches
our numerical results accounting for finite barrier effects, and compare it
with previous works. We also show results for the full damping range. We
quantitatively study some aspects on the relation between mean first passage
time and the definition of a escape rate. To finish we apply our results and
considerations in the framework of force spectroscopy problems. We study the
differences on the predictions using the different theories and discuss the
role of $\gamma \dot{F}$ as the relevant parameter at high damping.",1212.4290v2
2013-01-18,Interfacial roughening in non-ideal fluids: Dynamic scaling in the weak- and strong-damping regime,"Interfacial roughening denotes the nonequilibrium process by which an
initially flat interface reaches its equilibrium state, characterized by the
presence of thermally excited capillary waves. Roughening of fluid interfaces
has been first analyzed by Flekkoy and Rothman [Phys. Rev. Lett. 75, 260
(1995)], where the dynamic scaling exponents in the weakly damped case in two
dimensions were found to agree with the Kardar-Parisi-Zhang universality class.
We extend this work by taking into account also the strong-damping regime and
perform extensive fluctuating hydrodynamics simulations in two dimensions using
the Lattice Boltzmann method. We show that the dynamic scaling behavior is
different in the weakly and strongly damped case.",1301.4468v2
2013-02-02,Achieving the Quantum Ground State of a Mechanical Oscillator using a Bose-Einstein Condensate with Back-Action and Cold Damping feedback schemes,"We present a detailed study to show the possibility of approaching the
quantum ground-state of a hybrid optomechanical quantum device formed by a
Bose-Einstein condensate (BEC) confined inside a high-finesse optical cavity
with an oscillatory end mirror. Cooling is achieved using two experimentally
realizable schemes: back-action cooling and cold damping quantum feedback
cooling. In both the schemes, we found that increasing the two body atom-atom
interaction brings the mechanical oscillator to its quantum ground state. It
has been observed that back-action cooling is more effective in the good cavity
limit while the cold damping cooling scheme is more relevant in the bad cavity
limit. It is also shown that in the cold damping scheme, the device is more
efficient in the presence of BEC than in the absence of BEC.",1302.0339v1
2013-02-27,Resonantly damped oscillations of elliptically shaped stratified emerging coronal loops,"The effects of both elliptical shape and stage of emergence of the coronal
loop on the resonant absorption of standing kink oscillations are studied. To
do so, a typical coronal loop is modeled as a zero-beta longitudinally
stratified cylindrical magnetic flux tube. We developed the connection formulae
for the resonant absorption of standing transversal oscillations of a coronal
loop with an elliptical shape, at various stages of its emergence. Using the
connection formulae, the dispersion relation is derived and solved numerically
to obtain the frequencies and damping rates of the fundamental and
first-overtone kink modes. Our numerical results show that both the elliptical
shape and stage of emergence of the loop alter the frequencies and damping
rates of the tube as well as the ratio of frequencies of the fundamental and
its first-overtone modes. However, the ratio of the oscillation frequency to
the damping rate is not affected by the tube shape and stage of its emergence
and also is independent of the density stratification parameter.",1302.6884v1
2013-02-28,Damping of Quantum Vibrations Revealed in Deep Sub-barrier Fusion,"We demonstrate that when two colliding nuclei approach each other, their
quantum vibrations are damped near the touching point. We show that this
damping is responsible for the fusion hindrance phenomena measured in the deep
sub-barrier fusion reactions. To show those, we for the first time apply the
random-phase-approximation (RPA) method to the two-body $^{16}$O + $^{16}$O and
$^{40}$Ca + $^{40}$Ca systems. We calculate the octupole transition strengths
for the two nuclei adiabatically approaching each other. The calculated
transition strength drastically decreases near the touching point, strongly
suggesting the vanishing of the quantum couplings between the relative motion
and the vibrational intrinsic degrees of freedom of each nucleus. Based on this
picture, we also calculate the fusion cross section for the $^{40}$Ca +
$^{40}$Ca system using the coupled-channel method with the damping factor
simulating the vanishing of the couplings. The calculated results reproduce
well the experimental data, indicating that the smooth transition from the
sudden to adiabatic processes indeed occurs in the deep sub-barrier fusion
reactions.",1302.7115v2
2013-03-14,Microwave-assisted switching of a nanomagnet: analytical determination of the optimal microwave field,"We analytically determine the optimal microwave field that allows for the
magnetization reversal of a nanomagnet modeled as a macrospin. This is done by
minimizing the total injected energy. The results are in good agreement with
the fields obtained numerically using the optimal control theory. For typical
values of the damping parameter, a weak microwave field is sufficient to induce
switching through a resonant process. The optimal field is orthogonal to the
magnetization direction at any time and modulated both in amplitude and
frequency. The dependence of the pulse shape on the applied field and damping
parameter is interpreted. The total injected energy is found to be
proportionnal to the energy barrier between the initial state and the saddle
point and to the damping parameter. This result may be used as a means for
probing the damping parameter in real nanoparticles.",1303.3501v4
2013-04-05,Nonlocal Gravity: Damping of Linearized Gravitational Waves,"In nonlocal general relativity, linearized gravitational waves are damped as
they propagate from the source to the receiver in the Minkowski vacuum.
Nonlocal gravity is a generalization of Einstein's theory of gravitation in
which nonlocality is due to the gravitational memory of past events. That
nonlocal gravity is dissipative is demonstrated in this paper within certain
approximation schemes. The gravitational memory drag leads to the decay of the
amplitude of gravitational waves given by the exponential damping factor exp
(-t/\tau), where $\tau$ depends on the kernel of nonlocal gravity. The damping
time $\tau$ is estimated for gravitational waves of current observational
interest and is found to be of the order of, or longer than, the age of the
universe.",1304.1769v1
2013-07-29,Damping of Primordial Gravitational Waves from Generalized Sources,"It has been shown that a cosmological background with an anisotropic stress
tensor, appropriate for a free streaming thermal neutrino background, can damp
primordial gravitational waves after they enter the horizon, and can thus
affect the CMB B-mode polarization signature due to such tensor modes. Here we
generalize this result, and examine the sensitivity of this effect to non-zero
neutrino masses, extra neutrino species, and also a possible relativistic
background of axions from axion strings. In particular, additional neutrinos
with cosmologically interesting neutrino masses at the O(1) eV level will
noticeably reduce damping compared to massless neutrinos for gravitational wave
modes with $k\tau_0 \approx 100-200$, where $\tau_0 \approx 2/H_0$ and $H_0$ is
the present Hubble parameter, while an axion background would produce a
phase-dependent damping distinct from that produced by neutrinos.",1307.7571v1
2013-10-29,Observational Study of Large Amplitude Longitudinal Oscillations in a Solar Filament,"On 20 August 2010 an energetic disturbance triggered damped large-amplitude
longitudinal (LAL) oscillations in almost an entire filament. In the present
work we analyze this periodic motion in the filament to characterize the
damping and restoring mechanism of the oscillation. Our method involves placing
slits along the axis of the filament at different angles with respect to the
spine of the filament, finding the angle at which the oscillation is clearest,
and fitting the resulting oscillation pattern to decaying sinusoidal and Bessel
functions. These functions represent the equations of motion of a pendulum
damped by mass accretion. With this method we determine the period and the
decaying time of the oscillation. Our preliminary results support the theory
presented by Luna and Karpen (2012) that the restoring force of LAL
oscillations is solar gravity in the tubes where the threads oscillate, and the
damping mechanism is the ongoing accumulation of mass onto the oscillating
threads. Following an earlier paper, we have determined the magnitude and
radius of curvature of the dipped magnetic flux tubes hosting a thread along
the filament, as well as the mass accretion rate of the filament threads, via
the fitted parameters.",1310.7657v1
2013-11-01,Kinetic theory of acoustic-like modes in nonextensive pair plasmas,"The low-frequency acoustic-like modes in a pair plasma (electron-positron or
pair-ion) is studied by employing a kinetic theory model based on the Vlasov
and Poisson's equation with emphasizing the Tsallis's nonextensive statistics.
The possibility of the acoustic-like modes and their properties in both fully
symmetric and temperature-asymmetric cases are examined by studying the
dispersion relation, Landau damping and instability of modes. The resultant
dispersion relation in this study is compatible with the acoustic branch of the
experimental data [W. Oohara, D. Date, and R. Hatakeyama, Phys. Rev. Lett. 95,
175003 (2005)], in which the electrostatic waves have been examined in a pure
pair-ion plasma. Particularly, our study reveals that the occurrence of growing
or damped acoustic-like modes depends strongly on the nonextensivity of the
system as a measure for describing the long-range Coulombic interactions and
correlations in the plasma. The mechanism that leads to the unstable modes lies
in the heart of the nonextensive formalism yet, the mechanism of damping is the
same developed by Landau. Furthermore, the solutions of acoustic-like waves in
an equilibrium Maxwellian pair plasma are recovered in the extensive limit
($q\rightarrow1$), where the acoustic modes have only the Landau damping and no
growth.",1311.0193v1
2013-11-29,Exploring viscous damping in undergraduate Physics laboratory using electromagnetically coupled oscillators,"We design a low-cost, electromagnetically coupled, simple harmonic oscillator
and demonstrate free, damped and forced oscillations in an under-graduate (UG)
Physics laboratory. It consists of a spring-magnet system that can oscillate
inside a cylinder around which copper coils are wound. Such demonstrations can
compliment the traditional way in which a Waves & Oscillations course is taught
and offers a richer pedagogical experience for students. We also show that with
minimal modifications, it can be used to probe the magnitude of viscous damping
forces in liquids by analyzing the oscillations of an immersed magnet. Finally,
we propose some student activities to explore non-linear damping effects and
their characterization using this apparatus.",1311.7489v1
2013-12-18,Radiative damping and synchronization in a graphene-based terahertz emitter,"We investigate the collective electron dynamics in a recently proposed
graphene-based terahertz emitter under the influence of the radiative damping
effect, which is included self-consistently in a molecular dynamics approach.
We show that under appropriate conditions synchronization of the dynamics of
single electrons takes place, leading to a rise of the oscillating component of
the charge current. The synchronization time depends dramatically on the
applied dc electric field and electron scattering rate, and is roughly
inversely proportional to the radiative damping rate that is determined by the
carrier concentration and the geometrical parameters of the device. The
emission spectra in the synchronized state, determined by the oscillating
current component, are analyzed. The effective generation of higher harmonics
for large values of the radiative damping strength is demonstrated.",1312.5193v1
2014-01-20,Analysis of mean cluster size in directed compact percolation near a damp wall,"We investigate the behaviour of the mean size of directed compact percolation
clusters near a damp wall in the low-density region, where sites in the bulk
are wet (occupied) with probability $p$ while sites on the wall are wet with
probability $p_w$. Methods used to find the exact solution for the dry case
($p_w=0$) and the wet case ($p_w=1$) turn out to be inadequate for the damp
case. Instead we use a series expansion for the $p_w=2p$ case to obtain a
second order inhomogeneous differential equation satisfied by the mean size,
which exhibits a critical exponent $\gamma=2$, in common with the wet wall
result. For the more general case of $p_w=rp$, with $r$ rational, we use a
modular arithmetic method of finding ODEs and obtain a fourth order homogeneous
ODE satisfied by the series. The ODE is expressed exactly in terms of $r$. We
find that in the damp region $0<r<2$ the critical exponent $\gamma^{\rm
damp}=1$, in common with the dry wall result.",1401.4793v1
2014-02-13,On the Convergence of Approximate Message Passing with Arbitrary Matrices,"Approximate message passing (AMP) methods and their variants have attracted
considerable recent attention for the problem of estimating a random vector
$\mathbf{x}$ observed through a linear transform $\mathbf{A}$. In the case of
large i.i.d. zero-mean Gaussian $\mathbf{A}$, the methods exhibit fast
convergence with precise analytic characterizations on the algorithm behavior.
However, the convergence of AMP under general transforms $\mathbf{A}$ is not
fully understood. In this paper, we provide sufficient conditions for the
convergence of a damped version of the generalized AMP (GAMP) algorithm in the
case of quadratic cost functions (i.e., Gaussian likelihood and prior). It is
shown that, with sufficient damping, the algorithm is guaranteed to converge,
although the amount of damping grows with peak-to-average ratio of the squared
singular values of the transforms $\mathbf{A}$. This result explains the good
performance of AMP on i.i.d. Gaussian transforms $\mathbf{A}$, but also their
difficulties with ill-conditioned or non-zero-mean transforms $\mathbf{A}$. A
related sufficient condition is then derived for the local stability of the
damped GAMP method under general cost functions, assuming certain strict
convexity conditions.",1402.3210v3
2014-08-18,Kirchhoff equations with strong damping,"We consider Kirchhoff equations with strong damping, namely with a friction
term which depends on a power of the ""elastic"" operator. We address local and
global existence of solutions in two different regimes depending on the
exponent in the friction term.
  When the exponent is greater than 1/2, the dissipation prevails, and we
obtain global existence in the energy space assuming only degenerate
hyperbolicity and continuity of the nonlinear term. When the exponent is less
than 1/2, we assume strict hyperbolicity and we consider a phase space
depending on the continuity modulus of the nonlinear term and on the exponent
in the damping. In this phase space we prove local existence, and global
existence if initial data are small enough.
  The regularity we assume both on initial data and on the nonlinear term is
weaker than in the classical results for Kirchhoff equations with standard
damping.
  Proofs exploit some recent sharp results for the linearized equation and
suitably defined interpolation spaces.",1408.3908v1
2014-08-28,A convergent method for linear half-space kinetic equations,"We give a unified proof for the well-posedness of a class of linear
half-space equations with general incoming data and construct a Galerkin method
to numerically resolve this type of equations in a systematic way. Our main
strategy in both analysis and numerics includes three steps: adding damping
terms to the original half-space equation, using an inf-sup argument and
even-odd decomposition to establish the well-posedness of the damped equation,
and then recovering solutions to the original half-space equation. The proposed
numerical methods for the damped equation is shown to be quasi-optimal and the
numerical error of approximations to the original equation is controlled by
that of the damped equation. This efficient solution to the half-space problem
is useful for kinetic-fluid coupling simulations.",1408.6630v4
2014-09-02,Damping effects in hole-doped graphene: the relaxation-time approximation,"The dynamical conductivity of interacting multiband electronic systems
derived in Ref.[1] is shown to be consistent with the general form of the Ward
identity. Using the semiphenomenological form of this conductivity formula, we
have demonstrated that the relaxation-time approximation can be used to
describe the damping effects in weakly interacting multiband systems only if
local charge conservation in the system and gauge invariance of the response
theory are properly treated. Such a gauge-invariant response theory is
illustrated on the common tight-binding model for conduction electrons in
hole-doped graphene. The model predicts two distinctly resolved maxima in the
energy-loss-function spectra. The first one corresponds to the intraband
plasmons (usually called the Dirac plasmons). On the other hand, the second
maximum ($\pi$ plasmon structure) is simply a consequence of the van Hove
singularity in the single-electron density of states. The dc resistivity and
the real part of the dynamical conductivity are found to be well described by
the relaxation-time approximation, but only in the parametric space in which
the damping is dominated by the direct scattering processes. The ballistic
transport and the damping of Dirac plasmons are thus the questions that require
abandoning the relaxation-time approximation.",1409.0621v1
2014-10-13,Relaxation damping in oscillating contacts,"If a contact of two purely elastic bodies with no sliding (infinite
coefficient of friction) is subjected to superimposed oscillations in the
normal and tangential directions, then a specific damping appears, that is not
dependent on friction or dissipation in the material. We call this effect
""relaxation damping"". The rate of energy dissipation due to relaxation damping
is calculated in a closed analytic form for arbitrary axially-symmetric
contacts. In the case of equal frequency of normal and tangential oscillations,
the dissipated energy per cycle is proportional to the square of the amplitude
of tangential oscillation and to the absolute value of the amplitude of normal
oscillation, and is dependent on the phase shift between both oscillations. In
the case of low frequency tangential motion with superimposed high frequency
normal oscillations, the system acts as a tunable linear damper. Generalization
of the results for macroscopically planar, randomly rough surfaces is
discussed.",1410.3238v1
2014-11-13,Maximal correlation between flavor entanglement and oscillation damping due to localization effects,"Localization effects and quantum decoherence driven by the mass-eigenstate
wave packet propagation are shown to support a statistical correlation between
quantum entanglement and damped oscillations in the scenario of three-flavor
quantum mixing for neutrinos. Once the mass-eigenstates that support flavor
oscillations are identified as three-{\em qubit} modes, a decoherence scale can
be extracted from correlation quantifiers, namely the entanglement of formation
and the logarithmic negativity. Such a decoherence scale is compared with the
coherence length of damped oscillations. Damping signatures exhibited by flavor
transition probabilities as an effective averaging of the oscillating terms are
then explained as owing to loss of entanglement between mass modes involved in
the relativistic propagation.",1411.3634v1
2014-12-08,Magnetization Dynamics driven by Non-equilibrium Spin-Orbit Coupled Electron Gas,"The dynamics of magnetization coupled to an electron gas via s-d exchange
interaction is investigated by using density matrix technique. Our theory shows
that non-equilibrium spin accumulation induces a spin torque and the electron
bath leads to a damping of the magnetization. For the two-dimensional
magnetization thin film coupled to the electron gas with Rashba spin-orbit
coupling, the result for the spin-orbit torques is consistent with the previous
semi-classical theory. Our theory predicts a damping of the magnetization,
which is absent in the semi-classical theory. The magnitude of the damping due
to the electron bath is comparable to the intrinsic Gilbert damping and may be
important in describing the magnetization dynamics of the system.",1412.2479v1
2015-01-20,Damping of long wavelength collective modes in spinor Bose-Fermi mixtures,"Using an effective field theory we describe the low energy bosonic
excitations in a three dimensional ultra-cold mixture of spin-1 bosons and
spin-1/2 fermions. We establish an interesting fermionic excitation induced
generic damping of the usual undamped long wavelength bosonic collective
Goldstone modes. Two states with bosons forming either a ferromagnetic or polar
superfluid are studied. The linear dispersion of the bosonic Bogoliubov
excitations is preserved with a renormalized sound velocity. For the polar
superfluid we find both gapless modes (density and spin) are damped, whereas in
the ferromagnetic superfluid we find the density (spin) mode is (not) damped.
We argue quite generally that this holds for any mixture of bosons and fermions
that are coupled through at least a density-density interaction. We discuss the
implications of our many-body interaction results for experiments on Bose-Fermi
mixtures.",1501.05015v2
2015-01-27,Non-linear fluctuation effects in dynamics of freely suspended film,"Long-scale dynamic fluctuation phenomena in freely suspended films is
analyzed. We consider isotropic films that, say, can be pulled from bulk
smectic A liquid crystals. The key feature of such objects is possibility of
bending deformations of the film. The bending (also known as flexular) mode
turns out to be anomalously weakly attenuated. In the harmonic approximation
there is no viscous-like damping of the bending mode, proportional to q^2 (q is
the wave vector of the mode), since it is forbidden by the rotational symmetry.
Therefore the bending mode is strongly affected by non-linear dynamic
fluctuation effects. We calculate the dominant fluctuation contributions to the
damping of the bending mode due to its coupling to the in-plane viscous mode,
that restores the viscous-like q^2 damping of the bending mode. Our
calculations are performed in the framework of the perturbation theory where
the coupling of the modes is assumed to be small, then the bending mode damping
is relatively weak. We discuss our results in the context of existing
experiments and numeric simulations of the freely suspended films and propose
possible experimental observations of our predictions.",1501.06703v1
2015-01-30,Intrinsic Damping of Collective Spin Modes in a Two-Dimensional Fermi Liquid with Spin-Orbit Coupling,"A Fermi liquid with spin-orbit coupling (SOC) is expected to support a new
kind of collective modes: oscillations of magnetization in the absence of the
magnetic field. We show that these modes are damped by the electron-electron
interaction even in the limit of an infinitely long wavelength (q = 0). The
linewidth of the collective mode is on the order of {\Delta}^2=E_F , where
{\Delta} is a characteristic spin-orbit energy splitting and E_F is the Fermi
energy. Such damping is in a stark contrast to known damping mechanisms of both
charge and spin collective modes in the absence of SOC, all of which disappear
at q = 0, and arises because none of the components of total spin is conserved
in the presence of SOC.",1502.00027v1
2015-02-01,Nonlocal Damping of Helimagnets in One-Dimensional Interacting Electron Systems,"We investigate the magnetization relaxation of a one-dimensional helimagnetic
system coupled to interacting itinerant electrons. The relaxation is assumed to
result from the emission of plasmons, the elementary excitations of the
one-dimensional interacting electron system, caused by slow changes of the
magnetization profile. This dissipation mechanism leads to a highly nonlocal
form of magnetization damping that is strongly dependent on the
electron-electron interaction. Forward scattering processes lead to a spatially
constant damping kernel, while backscattering processes produce a spatially
oscillating contribution. Due to the nonlocal damping, the thermal fluctuations
become spatially correlated over the entire system. We estimate the
characteristic magnetization relaxation times for magnetic quantum wires and
nuclear helimagnets.",1502.00268v2
2015-07-21,Onboard Calibration Circuit for the Front-end Electronics of DAMPE BGO Calorimeter,"An onboard calibration circuit has been designed for the front-end
electronics (FEE) of DAMPE BGO Calorimeter. It is mainly composed of a 12 bit
DAC, an operation amplifier and an analog switch. Test results showed that a
dynamic range of 0 ~ 30 pC with a precision of 5 fC was achieved, which meets
the requirements of the front-end electronics. Furthermore, it is used to test
the trigger function of the FEEs. The calibration circuit has been implemented
and verified by all the environmental tests for both Qualification Model and
Flight Model of DAMPE. The DAMPE satellite will be launched at the end of 2015
and the calibration circuit will perform onboard calibration in space.",1507.05862v1
2015-07-30,Reservoir interactions during Bose-Einstein condensation: modified critical scaling in the Kibble-Zurek mechanism of defect formation,"As a test of the Kibble-Zurek mechanism (KZM) of defect formation, we
simulate the Bose-Einstein condensation transition in a toroidally confined
Bose gas using the stochastic projected Gross-Pitaevskii equation (SPGPE), with
and without the energy-damping reservoir interaction. Energy-damping alters the
scaling of the winding number distribution with the quench time - a departure
from the universal KZM theory that relies on equilibrium critical exponents.
Numerical values are obtained for the correlation-length critical exponent
$\nu$ and the dynamical critical exponent $z$ for each variant of reservoir
interaction theory. The energy-damping reservoir interactions cause significant
modification of the dynamical critical exponent of the phase transition, whilst
preserving the essential KZM critical scaling behavior. Comparison of numerical
and analytical two-point correlation functions further illustrates the effect
of energy damping on the correlation length during freeze out.",1507.08357v1
2015-08-23,Melnikov chaos in a modified Rayleigh-Duffing oscillator with $ φ^6$ potential,"The chaotic behavior of the modified Rayleigh-Duffing oscillator with $
\phi^6$ potential and external excitation which modeles ship rolling motions
are investigated both analytically and numerically. Melnikov method is applied
and the conditions for the existence of homoclinic and heteroclinic chaos are
obtained. The effects of nonlinear damping on roll motion of ships are analyzed
in detail. As it is known, nonlinear roll damping is a very important parameter
in estimating ship reponses. The predictions are tested numerical simulations
based on the basin of attraction. We conclude that certains quadratic damping
effects are contrary to cubic damping effect.",1508.05664v1
2015-09-23,Quantum Error-Correcting Codes for Qudit Amplitude Damping,"Traditional quantum error-correcting codes are designed for the depolarizing
channel modeled by generalized Pauli errors occurring with equal probability.
Amplitude damping channels model, in general, the decay process of a multilevel
atom or energy dissipation of a bosonic system at zero temperature. We discuss
quantum error-correcting codes adapted to amplitude damping channels for higher
dimensional systems (qudits). For multi-level atoms, we consider a natural kind
of decay process, and for bosonic systems,we consider the qudit amplitude
damping channel obtained by truncating the Fock basis of the bosonic modes to a
certain maximum occupation number. We construct families of
single-error-correcting quantum codes that can be used for both cases. Our
codes have larger code dimensions than the previously known
single-error-correcting codes of the same lengths. Additionally, we present
families of multi-error correcting codes for these two channels, as well as
generalizations of our construction technique to error-correcting codes for the
qutrit $V$ and $\Lambda$ channels.",1509.06829v1
2015-10-07,"Tunable damping, saturation magnetization, and exchange stiffness of half-Heusler NiMnSb thin films","The half-metallic half-Heusler alloy NiMnSb is a promising candidate for
applications in spintronic devices due to its low magnetic damping and its rich
anisotropies. Here we use ferromagnetic resonance (FMR) measurements and
calculations from first principles to investigate how the composition of the
epitaxially grown NiMnSb influences the magnetodynamic properties of saturation
magnetization $M_S$, Gilbert damping $\alpha$, and exchange stiffness $A$.
$M_S$ and $A$ are shown to have a maximum for stoichiometric composition, while
the Gilbert damping is minimum. We find excellent quantitative agreement
between theory and experiment for $M_S$ and $\alpha$. The calculated $A$ shows
the same trend as the experimental data, but has a larger magnitude.
Additionally to the unique in-plane anisotropy of the material, these
tunabilities of the magnetodynamic properties can be taken advantage of when
employing NiMnSb films in magnonic devices.",1510.01894v1
2015-10-09,Determining form and data assimilation algorithm for weakly damped and driven Korteweg-de Vries equaton- Fourier modes case,"We show that the global attractor of a weakly damped and driven Korteweg-de
Vries equation (KdV) is embedded in the long-time dynamics of an ordinary
differential equation called a determining form. In particular, there is a
one-to-one identification of the trajectories in the global attractor of the
damped and driven KdV and the steady state solutions of the determining form.
Moreover, we analyze a data assimilation algorithm (down-scaling) for the
weakly damped and driven KdV. We show that given a certain number of low
Fourier modes of a reference solution of the KdV equation, the algorithm
recovers the full reference solution at an exponential rate in time.",1510.02730v1
2015-10-27,Remarks on 1-D Euler Equations with Time-Decayed Damping,"We study the 1-d isentropic Euler equations with time-decayed damping
\begin{equation} \left\{ \begin{aligned} &\partial_t \rho+\partial_x(\rho u)=0,
\\ &\partial_t(\rho u)+ \partial_x(\rho
u^2)+\partial_xp(\rho)=-\frac{\mu}{1+t}\rho u,\\
&\rho|_{t=0}=1+\varepsilon\rho_0(x),u|_{t=0}=\varepsilon u_0(x). \end{aligned}
\right. \nonumber \end{equation}
  This work is inspired by a recent work of F. Hou, I. Witt and H.C. Yin
\cite{Hou01}. In \cite{Hou01}, they proved a global existence and blow-up
result of 3-d irrotational Euler flow with time-dependent damping. In the 1-d
case, we will prove a different result when the damping decays of order $-1$
with respect to the time $t$. More precisely, when $\mu>2$, we prove the global
existence of the 1-d Euler system. While when $0\leq\mu\leq2 $, we will prove
the blow up of $C^1$ solutions.",1510.08115v1
2016-01-04,Generalized Bloch's theorem for viscous metamaterials: Dispersion and effective properties based on frequencies and wavenumbers that are simultaneously complex,"It is common for dispersion curves of damped periodic materials to be based
on real frequencies versus complex wavenumbers or, conversely, real wavenumbers
versus complex frequencies. The former condition corresponds to harmonic wave
motion where a driving frequency is prescribed and where attenuation due to
dissipation takes place only in space alongside spatial attenuation due to
Bragg scattering. The latter condition, on the other hand, relates to free wave
motion admitting attenuation due to energy loss only in time while spatial
attenuation due to Bragg scattering also takes place. Here, we develop an
algorithm for 1D systems that provides dispersion curves for damped free wave
motion based on frequencies and wavenumbers that are permitted to be
simultaneously complex. This represents a generalized application of Bloch's
theorem and produces a dispersion band structure that fully describes all
attenuation mechanisms, in space and in time. The algorithm is applied to a
viscously damped mass-in-mass metamaterial exhibiting local resonance. A
frequency-dependent effective mass for this damped infinite chain is also
obtained.",1601.00683v1
2016-02-05,Protecting entanglement from correlated amplitude damping channel using weak measurement and quantum measurement reversal,"Based on the quantum technique of weak measurement, we propose a scheme to
protect the entanglement from correlated amplitude damping decoherence. In
contrast to the results of memoryless amplitude damping channel, we show that
the memory effects play a significant role in the suppression of entanglement
sudden death and protection of entanglement under severe decoherence. Moreover,
we find that the initial entanglement could be drastically amplified by the
combination of weak measurement and quantum measurement reversal even under the
correlated amplitude damping channel. The underlying mechanism can be
attributed to the probabilistic nature of weak measurements.",1602.01998v1
2016-03-10,Stability Analysis of Networked Systems Containing Damped and Undamped Nodes,"This paper answers the question if a qualitatively heterogeneous passive
networked system containing damped and undamped nodes shows consensus in the
output of the nodes in the long run. While a standard Lyapunov analysis shows
that the damped nodes will always converge to a steady-state value, the
convergence of the undamped nodes is much more delicate and depends on the
parameter values of the network as well as on the topology of the graph. A
complete stability analysis is presented based on an eigenvector analysis
involving the mass values and the topology of both the original graph and the
reduced graph obtained by a Kron reduction that eliminates the damped nodes.",1603.03477v1
2016-04-11,All-Optical Study of Tunable Ultrafast Spin Dynamics in [Co/Pd]-NiFe Systems: The Role of Spin-Twist Structure on Gilbert Damping,"We investigate optically induced ultrafast magnetization dynamics in [Co(0.5
nm)/Pd(1 nm)]x5/NiFe(t) exchange-spring samples with tilted perpendicular
magnetic anisotropy using a time-resolved magneto-optical Kerr effect
magnetometer. The competition between the out-of-plane anisotropy of the hard
layer, the in-plane anisotropy of the soft layer and the applied bias field
reorganizes the spins in the soft layer, which are modified further with the
variation in t. The spin-wave spectrum, the ultrafast demagnetization time, and
the extracted damping coefficient all depend on the spin distribution in the
soft layer, while the latter two also depend on the spin-orbit coupling between
the Co and Pd layers. The spin-wave spectra change from multimode to
single-mode as t increases. At the maximum field reached in this study, H=2.5
kOe, the damping shows a nonmonotonic dependence on t with a minimum at t=7.5
nm. For t<7.5 nm, intrinsic effects dominate, whereas for t>7.5 nm, extrinsic
effects govern the damping mechanisms.",1604.02998v1
2016-04-29,Nonlinear Landau damping of wave envelopes in a quantum plasma,"The nonlinear theory of Landau damping of electrostatic wave envelopes (WEs)
is revisited in a quantum electron-positron (EP) pair plasma. Starting from a
Wigner-Moyal equation coupled to the Poisson equation and applying the multiple
scale technique, we derive a nonlinear Schr{\""o}dinger (NLS) equation which
governs the evolution of electrostatic WEs. It is shown that the coefficients
of the NLS equation, including the nonlocal nonlinear term, which appears due
to the resonant particles having group velocity of the WEs, are significantly
modified by the particle dispersion. The effects of the quantum parameter $H$
(the ratio of the plasmon energy to the thermal energy densities), associated
with the particle dispersion, are examined on the Landau damping rate of
carrier waves, as well as on the modulational instability of WEs. It is found
that the Landau damping rate and the decay rate of the solitary wave amplitude
are greatly reduced compared to their classical values $(H=0)$.",1604.08751v4
2016-07-21,The Noisy Oscillator : Random Mass and Random Damping,"The problem of a linear damped noisy oscillator is treated in the presence of
two multiplicative sources of noise which imply a random mass and random
damping. The additive noise and the noise in the damping are responsible for an
influx of energy to the oscillator and its dissipation to the surrounding
environment. A random mass implies that the surrounding molecules not only
collide with the oscillator but may also adhere to it, thereby changing its
mass. We present general formulas for the first two moments and address the
question of mean and energetic stabilities. The phenomenon of stochastic
resonance, i.e. the expansion due to the noise of a system response to an
external periodic signal, is considered for separate and joint action of two
sources of noise and their characteristics.",1607.06289v2
2016-09-06,JRSP of three-particle state via three tripartite GHZ class in quantum noisy channels,"We present a scheme for joint remote state preparation (JRSP) of
three-particle state via three tripartite Greenberger-Horne-Zeilinger (GHZ)
entangled states as the quantum channel linking the parties. We use eight-qubit
mutually orthogonal basis vector as measurement point of departure. The
likelihood of success for this scheme has been found to be $1/8$. However, by
putting some special cases into consideration, the chances can be ameliorated
to $1/4$ and $1$. The effects of amplitude-damping noise, phase-damping noise
and depolarizing noise on this scheme have been scrutinized and the analytical
derivations of fidelities for the quantum noisy channels have been presented.
We found that for $0.55\leq\eta\leq1$, the states conveyed through depolarizing
channel lose more information than phase-damping channel while the information
loss through amplitude damping channel is most minimal.",1609.01538v3
2016-09-22,Damping of nonlinear standing kink oscillations: a numerical study,"We aim to study the standing fundamental kink mode of coronal loops in the
nonlinear regime, investigating the changes in energy evolution in the
cross-section and oscillation amplitude of the loop which are related to
nonlinear effects, in particular to the development of the Kelvin-Helmholtz
instability (KHI). We run idea, high-resolution three-dimensional (3D)
magnetohydrodynamics (MHD) simulations, studying the influence of the initial
velocity amplitude and the inhomogeneous layer thickness. We model the coronal
loop as a straight, homogeneous magnetic flux tube with an outer inhomogeneous
layer, embedded in a straight, homogeneous magnetic field. We find that, for
low amplitudes which do not allow for the KHI to develop during the simulated
time, the damping time agrees with the theory of resonant absorption. However,
for higher amplitudes, the presence of KHI around the oscillating loop can
alter the loop's evolution, resulting in a significantly faster damping than
predicted by the linear theory in some cases. This questions the accuracy of
seismological methods applied to observed damping profiles, based on linear
theory.",1609.06883v1
2016-09-28,Nonlinear damping and dephasing in nanomechanical systems,"We present a microscopic theory of nonlinear damping and dephasing of
low-frequency eigenmodes in nano- and micro-mechanical systems. The mechanism
of the both effects is scattering of thermally excited vibrational modes off
the considered eigenmode. The scattering is accompanied by energy transfer of
$2\hbar\omega_0$ for nonlinear damping and is quasieleastic for dephasing. We
develop a formalism that allows studying both spatially uniform systems and
systems with a strong nonuniformity, which is smooth on the typical wavelength
of thermal modes but not their mean free path. The formalism accounts for the
decay of thermal modes, which plays a major role in the nonlinear damping and
dephasing. We identify the nonlinear analogs of the Landau-Rumer,
thermoelastic, and Akhiezer mechanisms and find the dependence of the
relaxation parameters on the temperature and the geometry of a system.",1609.08714v1
2016-09-24,Parametric Landau damping of space charge modes,"Landau damping is the mechanism of plasma and beam stabilization; it arises
through energy transfer from collective modes to the incoherent motion of
resonant particles. Normally this resonance requires the resonant particle's
frequency to match the collective mode frequency. We have identified an
important new damping mechanism, {\it parametric Landau damping}, which is
driven by the modulation of the mode-particle interaction. This reveals new
possibilities for stability control through manipulation of both particle and
mode-particle coupling spectra. We demonstrate the existence of parametric
Landau damping in a simulation of transverse coherent modes of bunched
accelerator beams with space charge.",1609.09393v3
2017-03-06,Damping dependence of spin-torque effects in thermally assisted magnetization reversal,"Thermal fluctuations of nanomagnets driven by spin-polarized currents are
treated via the Landau-Lifshitz-Gilbert equation as generalized to include both
the random thermal noise field and Slonczewski spin-transfer torque terms. The
magnetization reversal time of such a nanomagnet is then evaluated for wide
ranges of damping by using a method which generalizes the solution of the
so-called Kramers turnover problem for mechanical Brownian particles, thereby
bridging the very low damping and intermediate damping Kramers escape rates, to
the analogous magnetic turnover problem. The reversal time is then evaluated
for a nanomagnet with the free energy density given in the standard form of
superimposed easy-plane and in-plane easy-axis anisotropies with the dc bias
field along the easy axis.",1703.01879v5
2017-03-22,Direct Measurement of Kramers Turnover with a Levitated Nanoparticle,"Understanding the thermally activated escape from a metastable state is at
the heart of important phenomena such as the folding dynamics of proteins, the
kinetics of chemical reactions or the stability of mechanical systems. In 1940
Kramers calculated escape rates both in the high damping and the low damping
regime and suggested that the rate must have a maximum for intermediate
damping. This phenomenon, today known as the Kramers turnover, has triggered
important theoretical and numerical studies. However, to date there is no
direct and quantitative experimental verification of this turnover. Using a
nanoparticle trapped in a bi-stable optical potential we experimentally measure
the nanoparticle's transition rates for variable damping and directly resolve
the Kramers turnover. Our measurements are in agreement with an analytical
model that is free of adjustable parameters.",1703.07699v2
2017-08-05,Dynamic Sensitivity Study of MEMS Capacitive Acceleration Transducer Based on Analytical Squeeze Film Damping and Mechanical Thermoelasticity Approaches,"The dynamic behavior of a capacitive micro-electro-mechanical (MEMS)
accelerometer is evaluated by using a theoretical approach which makes use of a
squeeze film damping (SFD) model and ideal gas approach. The study investigates
the performance of the device as a function of the temperature, from 228 K to
398 K, and pressure, from 20 to 1000 Pa, observing the damping gas trapped
inside de mechanical transducer. Thermoelastic properties of the silicon bulk
are considered for the entire range of temperature. The damping gases
considered are Air, Helium and Argon. The global behavior of the system is
evaluated considering the electro-mechanical sensitivity (SEM) as the main
figure of merit in frequency domain. The results show the behavior of the main
mechanism losses of SFD, as well as the dynamic sensitivity of the MEMS
transducer system, and are in good agreement with experimental dynamic results
behavior.",1708.01812v1
2017-08-07,"Chiral damping, chiral gyromagnetism and current-induced torques in textured one-dimensional Rashba ferromagnets","We investigate Gilbert damping, spectroscopic gyromagnetic ratio and
current-induced torques in the one-dimensional Rashba model with an additional
noncollinear magnetic exchange field. We find that the Gilbert damping differs
between left-handed and right-handed N\'eel-type magnetic domain walls due to
the combination of spatial inversion asymmetry and spin-orbit interaction
(SOI), consistent with recent experimental observations of chiral damping.
Additionally, we find that also the spectroscopic $g$ factor differs between
left-handed and right-handed N\'eel-type domain walls, which we call chiral
gyromagnetism. We also investigate the gyromagnetic ratio in the Rashba model
with collinear magnetization, where we find that scattering corrections to the
$g$ factor vanish for zero SOI, become important for finite spin-orbit
coupling, and tend to stabilize the gyromagnetic ratio close to its
nonrelativistic value.",1708.02008v2
2018-02-28,Beliaev Damping in Spin-$\frac{1}{2}$ Interacting Bosons with Spin-Orbit Coupling,"Beliaev damping provides one of the most important mechanisms for dissipation
of quasiparticles through beyond-mean-field effects at zero temperature. Here
we present the first analytical result of Beliaev damping in low-energy
excitations of spin-$\frac{1}{2}$ interacting bosons with equal Rashba and
Dresslhaus spin-orbit couplings. We identify novel features of Beliaev decay
rate due to spin-orbit coupling, in particular, it shows explicit dependence on
the spin-density interaction and diverges at the interaction-modified phase
boundary between the zero-momentum and plane-wave phases. This represents a
manifestation of the effect of spin-orbit coupling in the beyond-mean-field
regime, which by breaking Galilean invariance couples excitations in the
density- and spin-channels. By describing the Beliaev damping in terms of the
observable dynamic structure factors, our results allow direct experimental
access within current facilities.",1802.10295v1
2018-04-02,Anisotropic Gilbert damping in perovskite La$_{0.7}$Sr$_{0.3}$MnO$_{3}$ thin film,"The viscous Gilbert damping parameter governing magnetization dynamics is of
primary importance for various spintronics applications. Although, the damping
constant is believed to be anisotropic by theories. It is commonly treated as a
scalar due to lack of experimental evidence. Here, we present an elaborate
angle dependent broadband ferromagnetic resonance study of high quality
epitaxial La$_{0.7}$Sr$_{0.3}$MnO$_{3}$ films. Extrinsic effects are suppressed
and we show convincing evidence of anisotropic damping with twofold symmetry at
room temperature. The observed anisotropic relaxation is attributed to the
magnetization orientation dependence of the band structure. In addition, we
demonstrated that such anisotropy can be tailored by manipulating the stain.
This work provides new insights to understand the mechanism of magnetization
relaxation.",1804.00554v1
2018-04-15,Reevaluation of radiation reaction and consequences for light-matter interactions at the nanoscale,"In the context of electromagnetism and nonlinear optical interactions damping
is generally introduced as a phenomenological, viscous term that dissipates
energy, proportional to the temporal derivative of the polarization. Here, we
follow the radiation reaction method presented in [G. W. Ford and R. F.
O'Connell, Phys. Lett. A, 157, 217 (1991)], which applies to non-relativistic
electrons of finite size, to introduce an explicit reaction force in the
Newtonian equation of motion, and derive a hydrodynamic equation that offers
new insight on the influence of damping in generic plasmas, metal-based and/or
dielectric structures. In these settings, we find new damping-dependent linear
and nonlinear source terms that suggest the damping coefficient is proportional
to the local charge density, and nonlocal contributions that stem from the
spatial derivative of the magnetic field and discuss the conditions that could
modify both linear and nonlinear electromagnetic responses.",1804.05369v1
2018-04-30,Wave-like blow-up for semilinear wave equations with scattering damping and negative mass term,"In this paper we establish blow-up results and lifespan estimates for
semilinear wave equations with scattering damping and negative mass term for
subcritical power, which is the same as that of the corresponding problem
without mass term, and also the same as that of the corresponding problem
without both damping and mass term. For this purpose, we have to use the
comparison argument twice, due to the damping and mass term, in additional to a
key multiplier. Finally, we get the desired results by an iteration argument.",1804.11073v3
2019-05-23,Strauss exponent for semilinear wave equations with scattering space dependent damping,"It is believed or conjectured that the semilinear wave equations with
scattering space dependent damping admit the Strauss critical exponent, see
Ikehata-Todorova-Yordanov \cite{ITY}(the bottom in page 2) and
Nishihara-Sobajima-Wakasugi \cite{N2}(conjecture iii in page 4). In this work,
we are devoted to showing the conjecture is true at least when the decay rate
of the space dependent variable coefficients before the damping is larger than
2. Also, if the nonlinear term depends only on the derivative of the solution,
we may prove the upper bound of the lifespan is the same as that of the
solution of the corresponding problem without damping. This shows in another
way the \lq\lq hyperbolicity"" of the equation.",1905.09445v2
2019-05-24,Multicomponent Dark Matter in the Light of CALET and DAMPE,"In the light of the latest measurements on the total $e^+ + e^-$ flux by
CALET and DAMPE experiments, we revisit the multicomponent leptonically
decaying dark matter (DM) explanations to the cosmic-ray electron/positron
excesses observed previously. Especially, we use the single and
double-component DM models to explore the compatibility of the AMS-02 positron
fraction with the new CALET or DAMPE data. It turns out that neither single nor
double-component DM models are able to fit the AMS-02 positron fraction and
DAMPE total $e^+ + e^-$ flux data simultaneously. On the other hand, for the
combined AMS-02 and CALET dataset, both the single and double-component DM
models can provide reasonable fits. If we further take into the diffuse
$\gamma$-ray constraints from Fermi-LAT, only the double-component DM models
are allowed.",1905.10136v3
2019-05-30,Quantum dynamical speedup in correlated noisy channels,"The maximal evolution speed of a quantum system can be represented by quantum
speed limit time (QSLT).We investigate QSLT of a two-qubit system passing
through a correlated channel (amplitude damping, phase damping, and
depolarizing).By adjusting the correlation parameter of channel and the initial
entanglement,a method to accelerate the evolution speed of the system for some
specific channels is proposed.It is shown that, in amplitude damping channel
and depolarizing channel,QSLT may be shortened in some cases by increasing
correlation parameter of the channel and initial entanglement, which are in
sharp contrast to phase damping channel.In particular, under depolarizing
channels, the transition from no-speedup evolution to speedup evolution for the
system can be realized by changing correlation strength of the channel.",1905.12911v3
2020-07-10,Decentralized Frequency Control using Packet-based Energy Coordination,"This paper presents a novel frequency-responsive control scheme for
demand-side resources, such as electric water heaters. A frequency-dependent
control law is designed to provide damping from distributed energy resources
(DERs) in a fully decentralized fashion. This local control policy represents a
frequency-dependent threshold for each DER that ensures that the aggregate
response provides damping during frequency deviations. The proposed
decentralized policy is based on an adaptation of a packet-based DER
coordination scheme where each device send requests for energy access (also
called an ""energy packet"") to an aggregator. The number of previously accepted
active packets can then be used a-priori to form an online estimate of the
aggregate damping capability of the DER fleet in a dynamic power system. A
simple two-area power system is used to illustrate and validate performance of
the decentralized control policy and the accuracy of the online damping
estimating for a fleet of 400,000 DERs.",2007.05624v1
2020-07-30,Origin of micron-scale propagation lengths of heat-carrying acoustic excitations in amorphous silicon,"The heat-carrying acoustic excitations of amorphous silicon are of interest
because their mean free paths may approach micron scales at room temperature.
Despite extensive investigation, the origin of the weak acoustic damping in the
heat-carrying frequencies remains a topic of debate. Here, we report
measurements of the thermal conductivity mean free path accumulation function
in amorphous silicon thin films from 60 - 315 K using transient grating
spectroscopy. With additional picosecond acoustics measurements and considering
the known frequency-dependencies of damping mechanisms in glasses, we
reconstruct the mean free paths from $\sim 0.1-3$ THz. The mean free paths are
independent of temperature and exhibit a Rayleigh scattering trend over most of
this frequency range. The observed trend is inconsistent with the predictions
of numerical studies based on normal mode analysis but agrees with diverse
measurements on other glasses. The micron-scale MFPs in amorphous Si arise from
the absence of anharmonic or two-level system damping in the sub-THz
frequencies, leading to heat-carrying acoustic excitations with
room-temperature damping comparable to that of other glasses at cryogenic
temperatures.",2007.15777v2
2010-05-23,Constraining phases of quark matter with studies of r-mode damping in neutron stars,"The r-mode instability in rotating compact stars is used to constrain the
phase of matter at high density. The color-flavor-locked phase with kaon
condensation (CFL-K0) and without (CFL) is considered in the temperature range
10^8K < T <10^{11} K. While the bulk viscosity in either phase is only
effective at damping the r-mode at temperatures T > 10^{11} K, the shear
viscosity in the CFL-K0 phase is the only effective damping agent all the way
down to temperatures T > 10^8 K characteristic of cooling neutron stars.
However, it cannot keep the star from becoming unstable to gravitational wave
emission for rotation frequencies f ~ 56-11 Hz at T ~ 10^8-10^9 K. Stars
composed almost entirely of CFL or CFL-K0 matter are ruled out by observation
of rapidly rotating neutron stars, indicating that dissipation at the
quark-hadron interface or nuclear crust interface must play a key role in
damping the instability.",1005.4161v1
2013-08-08,Small global solutions to the damped two-dimensional Boussinesq equations,"The two-dimensional (2D) incompressible Euler equations have been thoroughly
investigated and the resolution of the global (in time) existence and
uniqueness issue is currently in a satisfactory status. In contrast, the global
regularity problem concerning the 2D inviscid Boussinesq equations remains
widely open. In an attempt to understand this problem, we examine the damped 2D
Boussinesq equations and study how damping affects the regularity of solutions.
Since the damping effect is insufficient in overcoming the difficulty due to
the ""vortex stretching"", we seek unique global small solutions and the efforts
have been mainly devoted to minimizing the smallness assumption. By positioning
the solutions in a suitable functional setting (more precisely the homogeneous
Besov space $\mathring{B}^1_{\infty,1}$), we are able to obtain a unique global
solution under a minimal smallness assumption.",1308.1723v1
2013-08-21,Approximate quantum error correction for generalized amplitude damping errors,"We present analytic estimates of the performances of various approximate
quantum error correction schemes for the generalized amplitude damping (GAD)
qubit channel. Specifically, we consider both stabilizer and nonadditive
quantum codes. The performance of such error-correcting schemes is quantified
by means of the entanglement fidelity as a function of the damping probability
and the non-zero environmental temperature. The recovery scheme employed
throughout our work applies, in principle, to arbitrary quantum codes and is
the analogue of the perfect Knill-Laflamme recovery scheme adapted to the
approximate quantum error correction framework for the GAD error model. We also
analytically recover and/or clarify some previously known numerical results in
the limiting case of vanishing temperature of the environment, the well-known
traditional amplitude damping channel. In addition, our study suggests that
degenerate stabilizer codes and self-complementary nonadditive codes are
especially suitable for the error correction of the GAD noise model. Finally,
comparing the properly normalized entanglement fidelities of the best
performant stabilizer and nonadditive codes characterized by the same length,
we show that nonadditive codes outperform stabilizer codes not only in terms of
encoded dimension but also in terms of entanglement fidelity.",1308.4582v2
2014-03-28,Strichartz estimates and smooth attractors for a sub-quintic wave equation with fractional damping in bounded domains,"The work is devoted to Dirichlet problem for sub-quintic semi-linear wave
equation with damping damping term of the form $(-\Delta)^\alpha\partial_t u$,
$\alpha\in(0,\frac{1}{2})$, in bounded smooth domains of $\Bbb R^3$. It appears
that to prove well-posedness and develop smooth attractor theory for the
problem we need additional regularity of the solutions, which does not follow
from the energy estimate. Considering the original problem as perturbation of
the linear one the task is reduced to derivation of Strichartz type estimate
for the linear wave equation with fractional damping, which is the main feature
of the work. Existence of smooth exponential attractor for the natural
dynamical system associated with the problem is also established.",1403.7476v1
2017-01-08,Decentralized Robust Control for Damping Inter-area Oscillations in Power Systems,"As power systems become more and more interconnected, the inter-area
oscillations has become a serious factor limiting large power transfer among
different areas. Underdamped (Undamped) inter-area oscillations may cause
system breakup and even lead to large-scale blackout. Traditional damping
controllers include Power System Stabilizer (PSS) and Flexible AC Transmission
System (FACTS) controller, which adds additional damping to the inter-area
oscillation modes by affecting the real power in an indirect manner. However,
the effectiveness of these controllers is restricted to the neighborhood of a
prescribed set of operating conditions. In this paper, decentralized robust
controllers are developed to improve the damping ratios of the inter-area
oscillation modes by directly affecting the real power through the turbine
governing system. The proposed control strategy requires only local signals and
is robust to the variations in operation condition and system topology. The
effectiveness of the proposed robust controllers is illustrated by detailed
case studies on two different test systems.",1701.02036v1
2017-01-18,Ion beam test results of the Plastic Scintillator Detector of DAMPE,"The DArk Matter Particle Explorer (DAMPE) is one of the four satellites
within Strategic Pioneer Research Program in Space Science of the Chinese
Academy of Science (CAS). DAMPE can detect electrons, photons and ions in a
wide energy range (5 GeV to 10 TeV) and ions up to iron (100GeV to 100 TeV).
Plastic Scintillator Detector (PSD) is one of the four payloads in DAMPE,
providing e/{\gamma} separation and charge identification up to Iron. An ion
beam test was carried out for the Qualification Model of PSD in CERN with
40GeV/u Argon primary beams. The Birk's saturation and charge resolution of PSD
were investigated.",1701.04947v2
2017-01-18,DAMPE space mission: first data,"The DAMPE (DArk Matter Particle Explorer) satellite was launched on December
17, 2015 and started its data taking operation a few days later.
  DAMPE has a large geometric factor ($\sim~0.3\ m^2\ sr$) and provides good
tracking, calorimetric and charge measurements for electrons, gammas rays and
nuclei. This will allow precise measurement of cosmic ray spectra from tens of
$GeV$ up to about $100\ TeV$. In particular, the energy region between $1-100\
TeV$ will be explored with higher precision compared to previous experiments.
The various subdetectors allow an efficient identification of the electron
signal over the large (mainly proton-induced) background. As a result, the
all-electron spectrum will be measured with excellent resolution from few $GeV$
up to few $TeV$, thus giving the opportunity to identify possible contribution
of nearby sources. A report on the mission goals and status is presented,
together with the on-orbit detector performance and the first data coming from
space.",1701.05046v1
2017-01-25,Control Allocation for Wide Area Coordinated Damping,"In this work, a modal-based sparse control allocation (CA) is proposed for
coordinated and fault-tolerant wide-area damping controllers (WADCs). In our
proposed method, the supervisory CA only communicates with necessary actuators
to achieve the required damping performance and in case of actuator failures
(e.g., due to loss of communication or scheduling), capabilities of the
remaining actuators are fully used before the nominal performance is degraded.
This method offers the advantages of modular design where WADC is initially
designed to achieve satisfactory damping without the detailed knowledge of
actuators. In the next step, CA is designed to manage actuator failures and
limitations without the need to redesign the nominal WADC. The proposed
approach is applied to a modified $286$-bus Western Electricity Coordinating
Council (WECC) system to verify the feasibility on a complex power system.
Simulation results indicate the effectiveness of the proposed method in
coordinating multiple actuators and building resiliency.",1701.07456v1
2017-04-03,Suppression of plasma echoes and Landau damping in Sobolev spaces by weak collisions in a Vlasov-Fokker-Planck equation,"In this paper, we study Landau damping in the weakly collisional limit of a
Vlasov-Fokker-Planck equation with nonlinear collisions in the phase-space
$(x,v) \in \mathbb T_x^n \times \mathbb R^n_v$. The goal is four-fold: (A) to
understand how collisions suppress plasma echoes and enable Landau damping in
agreement with linearized theory in Sobolev spaces, (B) to understand how phase
mixing accelerates collisional relaxation, (C) to understand better how the
plasma returns to global equilibrium during Landau damping, and (D) to rule out
that collision-driven nonlinear instabilities dominate. We give an estimate for
the scaling law between Knudsen number and the maximal size of the perturbation
necessary for linear theory to be accurate in Sobolev regularity. We conjecture
this scaling to be sharp (up to logarithmic corrections) due to potential
nonlinear echoes in the collisionless model.",1704.00425v2
2017-03-20,Relativistic theory of magnetic inertia in ultrafast spin dynamics,"The influence of possible magnetic inertia effects has recently drawn
attention in ultrafast magnetization dynamics and switching. Here we derive
rigorously a description of inertia in the Landau-Lifshitz-Gilbert equation on
the basis of the Dirac-Kohn-Sham framework. Using the Foldy-Wouthuysen
transformation up to the order of $1/c^4$ gives the intrinsic inertia of a pure
system through the 2$^{\rm nd}$ order time-derivative of magnetization in the
dynamical equation of motion. Thus, the inertial damping $\mathcal{I}$ is a
higher order spin-orbit coupling effect, $\sim 1/c^4$, as compared to the
Gilbert damping $\Gamma$ that is of order $1/c^2$. Inertia is therefore
expected to play a role only on ultrashort timescales (sub-picoseconds). We
also show that the Gilbert damping and inertial damping are related to one
another through the imaginary and real parts of the magnetic susceptibility
tensor respectively.",1704.01559v1
2017-04-14,Impulse-Based Hybrid Motion Control,"The impulse-based discrete feedback control has been proposed in previous
work for the second-order motion systems with damping uncertainties. The
sate-dependent discrete impulse action takes place at zero crossing of one of
both states, either relative position or velocity. In this paper, the proposed
control method is extended to a general hybrid motion control form. We are
using the paradigm of hybrid system modeling while explicitly specifying the
state trajectories each time the continuous system state hits the guards that
triggers impulsive control actions. The conditions for a stable convergence to
zero equilibrium are derived in relation to the control parameters, while
requiring only the upper bound of damping uncertainties to be known. Numerical
examples are shown for an underdamped closed-loop dynamics with oscillating
transients, an upper bounded time-varying positive system damping, and system
with an additional Coulomb friction damping.",1704.04372v5
2017-04-19,Reliable channel-adapted error correction: Bacon-Shor code recovery from amplitude damping,"We construct two simple error correction schemes adapted to amplitude damping
noise for Bacon-Shor codes and investigate their prospects for fault-tolerant
implementation. Both consist solely of Clifford gates and require far fewer
qubits, relative to the standard method, to achieve correction to a desired
order in the damping rate. The first, employing one-bit teleportation and
single-qubit measurements, needs only one fourth as many physical qubits, while
the second, using just stabilizer measurements and Pauli corrections, needs
only half. We show that existing fault-tolerance methods can be employed for
the latter, while the former can be made to avoid potential catastrophic errors
and can easily cope with damping faults in ancilla qubits.",1704.05857v1
2017-04-24,Spin injection into silicon detected by broadband ferromagnetic resonance spectroscopy,"We studied the spin injection in a NiFe(Py)/Si system using broadband
ferromagnetic resonance spectroscopy. The Gilbert damping parameter of the Py
layer on top of the Si channel was determined as a function of the Si doping
concentration and Py layer thickness. For fixed Py thickness we observed an
increase of the Gilbert damping parameter with decreasing resistivity of the Si
channel. For a fixed Si doping concentration we measured an increasing Gilbert
damping parameter for decreasing Py layer thickness. No increase of the Gilbert
damping parameter was found Py/Si samples with an insulating interlayer. We
attribute our observations to an enhanced spin injection into the
low-resistivity Si by spin pumping.",1704.07006v1
2018-05-22,Uniqueness of the Cauchy datum for the tempered-in-time response and conductivity operator of a plasma,"We study the linear Vlasov equation with a given electric field $E \in
\mathcal{S}$, where $\mathcal{S}$ is the space of Schwartz functions. The
associated damped partial differential equation has a unique tempered solution,
which fixes the needed Cauchy datum. This tempered solution then converges to
the causal solution of the linear Vlasov equation when the damping parameter
goes to zero. This result allows us to define the plasma conductivity operator
$\sigma$, which gives the current density $j = \sigma (E)$ induced by the
electric field $E$. We prove that $\sigma$ is continuous from $\mathcal{S}$ to
its dual $\mathcal{S}^\prime$. We can treat rigorously the case of uniform
non-magnetized non-relativistic plasma (linear Landau damping) and the case of
uniform magnetized relativistic plasma (cyclotron damping). In both cases, we
demonstrate that the main part of the conductivity operator is a
pseudo-differential operator and we give its expression rigorously. This
matches the formal results widely used in the theoretical physics community.",1805.08733v3
2018-05-26,Stabilization for the wave equation with singular Kelvin-Voigt damping,"We consider the wave equation with Kelvin-Voigt damping in a bounded domain.
The exponential stability result proposed by Liu and Rao or T\'ebou for that
system assumes that the damping is localized in a neighborhood of the whole or
a part of the boundary under some consideration. In this paper we propose to
deal with this geometrical condition by considering a singular Kelvin-Voigt
damping which is localized faraway from the boundary. In this particular case
it was proved by Liu and Liu the lack of the uniform decay of the energy.
However, we show that the energy of the wave equation decreases logarithmically
to zero as time goes to infinity. Our method is based on the frequency domain
method. The main feature of our contribution is to write the resolvent problem
as a transmission system to which we apply a specific Carleman estimate.",1805.10430v1
2009-12-30,Finite dimensional attractor for a composite system of wave/plate equations with localised damping,"The long-term behaviour of solutions to a model for acoustic-structure
interactions is addressed; the system is comprised of coupled semilinear wave
(3D) and plate equations with nonlinear damping and critical sources. The
questions of interest are: existence of a global attractor for the dynamics
generated by this composite system, as well as dimensionality and regularity of
the attractor. A distinct and challenging feature of the problem is the
geometrically restricted dissipation on the wave component of the system. It is
shown that the existence of a global attractor of finite fractal dimension --
established in a previous work by Bucci, Chueshov and Lasiecka (Comm. Pure
Appl. Anal., 2007) only in the presence of full interior acoustic damping --
holds even in the case of localised dissipation. This nontrivial generalization
is inspired by and consistent with the recent advances in the study of wave
equations with nonlinear localised damping.",0912.5464v2
2011-11-14,New Electrodynamics of Pulsars,"We have recently proposed that Force-Free Electrodynamics (FFE) does not
apply to pulsars -- pulsars should be described by the high-conductivity limit
of Strong-Field Electrodynamics (SFE), which predicts an order-unity damping of
the Poynting flux, while FFE postulates zero damping. The strong damping result
has not been accepted by several pulsar experts, who claim that FFE basically
works and the Poynting flux damping can be arbitrarily small.
  Here we consider a thought experiment -- cylindrical periodic pulsar. We show
that FFE is incapable of describing this object, while SFE predictions are
physically plausible. The intrinsic breakdown of FFE should mean that the FFE
description of the singular current layer (the only region of magnetosphere
where FFE and the high-conductivity SFE differ) is incorrect. Then the
high-conductivity SFE should be the right theory for real pulsars too, and the
pure-FFE description of pulsars should be discarded.",1111.3377v1
2012-01-31,Parametric amplification and self-oscillation in a nanotube mechanical resonator,"A hallmark of mechanical resonators made from a single nanotube is that the
resonance frequency can be widely tuned. Here, we take advantage of this
property to realize parametric amplification and self-oscillation. The gain of
the parametric amplification can be as high as 18.2 dB and tends to saturate at
high parametric pumping due to nonlinear damping. These measurements allow us
to determine the coefficient of the linear damping force. The corresponding
damping rate is lower than the one obtained from the lineshape of the resonance
(without pumping), supporting the recently reported scenario that describes
damping in nanotube resonators by a nonlinear force. The possibility to combine
nanotube resonant mechanics and parametric amplification holds promise for
future ultra-low force sensing experiments.",1201.6557v1
2012-04-03,Inhomogeneity of the phase space of the damped harmonic oscillator under Levy noise,"The damped harmonic oscillator under symmetric L\'{e}vy white noise shows
inhomogeneous phase space, which is in contrast to the homogeneous one of the
same oscillator under the Gaussian white noise, as shown in a recent paper [I.
M. Sokolov, W. Ebeling, and B. Dybiec, Phys. Rev. E \textbf{83}, 041118
(2011)]. The inhomogeneity of the phase space shows certain correlation between
the coordinate and the velocity of the damped oscillator under symmetric
L\'{e}vy white noise. In the present work we further explore the physical
origin of these distinguished features and find that it is due to the
combination of the damped effect and heavy tail of the noise. We demonstrate
directly this in the reduced coordinate $\tilde{x}$ versus velocity $\tilde{v}$
plots and identify the physics of the anti-association of the coordinate and
velocity.",1204.0593v2
2012-04-24,Nonlocal feedback in ferromagnetic resonance,"Ferromagnetic resonance in thin films is analyzed under the influence of
spatiotemporal feedback effects. The equation of motion for the magnetization
dynamics is nonlocal in both space and time and includes isotropic, anisotropic
and dipolar energy contributions as well as the conserved Gilbert- and the
non-conserved Bloch-damping. We derive an analytical expression for the
peak-to-peak linewidth. It consists of four separate parts originated by
Gilbert damping, Bloch-damping, a mixed Gilbert-Bloch component and a
contribution arising from retardation. In an intermediate frequency regime the
results are comparable with the commonly used Landau-Lifshitz-Gilbert theory
combined with two-magnon processes. Retardation effects together with Gilbert
damping lead to a linewidth the frequency dependence of which becomes strongly
nonlinear. The relevance and the applicability of our approach to ferromagnetic
resonance experiments is discussed.",1204.5342v1
2014-05-12,Global Existence and Nonlinear Diffusion of Classical Solutions to Non-Isentropic Euler Equations with Damping in Bounded Domain,"We considered classical solutions to the initial boundary value problem for
non-isentropic compressible Euler equations with damping in multi-dimensions.
We obtained global a priori estimates and global existence results of classical
solutions to both non-isentropic Euler equations with damping and their
nonlinear diffusion equations under small data assumption. We proved the
pressure and velocity decay exponentially to constants, while the entropy and
density can not approach constants. Finally, we proved the pressure and
velocity of the non-isentropic Euler equations with damping converge
exponentially to those of their nonlinear diffusion equations when the time
goes to infinity.",1405.2842v3
2014-05-16,Damping of Confined Modes in a Ferromagnetic Thin Insulating Film: Angular Momentum Transfer Across a Nanoscale Field-defined Interface,"We observe a dependence of the damping of a confined mode of precessing
ferromagnetic magnetization on the size of the mode. The micron-scale mode is
created within an extended, unpatterned YIG film by means of the intense local
dipolar field of a micromagnetic tip. We find that damping of the confined mode
scales like the surface-to-volume ratio of the mode, indicating an interfacial
damping effect (similar to spin pumping) due to the transfer of angular
momentum from the confined mode to the spin sink of ferromagnetic material in
the surrounding film. Though unexpected for insulating systems, the measured
intralayer spin-mixing conductance $g_{\uparrow \downarrow} = 5.3 \times
10^{19} {\rm m}^{-2}$ demonstrates efficient intralayer angular momentum
transfer.",1405.4203v2
2014-06-03,Persistently damped transport on a network of circles,"In this paper we address the exponential stability of a system of transport
equations with intermittent damping on a network of $N \geq 2$ circles
intersecting at a single point $O$. The $N$ equations are coupled through a
linear mixing of their values at $O$, described by a matrix $M$. The activity
of the intermittent damping is determined by persistently exciting signals, all
belonging to a fixed class. The main result is that, under suitable hypotheses
on $M$ and on the rationality of the ratios between the lengths of the circles,
such a system is exponentially stable, uniformly with respect to the
persistently exciting signals. The proof relies on an explicit formula for the
solutions of this system, which allows one to track down the effects of the
intermittent damping.",1406.0731v4
2014-06-06,Damping of quasiparticles in a Bose-Einstein condensate coupled to an optical cavity,"We present a general theory for calculating the damping rate of elementary
density wave excitations in a Bose-Einstein condensate strongly coupled to a
single radiation field mode of an optical cavity. Thereby we give a detailed
derivation of the huge resonant enhancement in the Beliaev damping of a density
wave mode, predicted recently by K\'onya et al., Phys.~Rev.~A 89, 051601(R)
(2014). The given density-wave mode constitutes the polariton-like soft mode of
the self-organization phase transition. The resonant enhancement takes place,
both in the normal and ordered phases, outside the critical region. We show
that the large damping rate is accompanied by a significant frequency shift of
this polariton mode. Going beyond the Born-Markov approximation and determining
the poles of the retarded Green's function of the polariton, we reveal a strong
coupling between the polariton and a collective mode in the phonon bath formed
by the other density wave modes.",1406.1669v1
2016-05-02,Three types of nonlinear resonances,"We analyse different types of nonlinear resonances in a weakly damped Duffing
oscillator using bifurcation theory techniques. In addition to (i) odd
subharmonic resonances found on the primary branch of symmetric periodic
solutions with the forcing frequency and (ii) even subharmonic resonances due
to symmetry-broken periodic solutions that bifurcate off the primary branch and
also oscillate at the forcing frequency, we uncover (iii) novel resonance type
due to isolas of periodic solutions that are not connected to the primary
branch. These occur between odd and even resonances, oscillate at a fraction of
the forcing frequency, and give rise to a complicated resonance `curve' with
disconnected elements and high degree of multistability. We use bifurcation
continuation to compute resonance tongues in the plane of the forcing frequency
vs. the forcing amplitude for different but fixed values of the damping rate.
In this way, we demonstrate that identified here isolated resonances explain
the intriguing structure of ""patchy tongues"" observed for week damping and link
it to a seemingly unrelated phenomenon of ""bifurcation superstructure""
described for moderate damping.",1605.00858v2
2016-08-09,Optomechanical damping of a nanomembrane inside an optical ring cavity,"We experimentally and theoretically investigate mechanical nanooscillators
coupled to the light in an optical ring resonator made of dielectric mirrors.
We identify an optomechanical damping mechanism that is fundamentally different
to the well known cooling in standing wave cavities. While, in a standing wave
cavity the mechanical oscillation shifts the resonance frequency of the cavity
in a ring resonator the frequency does not change. Instead the position of the
nodes is shifted with the mechanical excursion. We derive the damping rates and
test the results experimentally with a silicon-nitride nanomembrane. It turns
out that scattering from small imperfections of the dielectric mirror coatings
has to be taken into account to explain the value of the measured damping rate.
We extend our theoretical model and regard a second reflector in the cavity
that captures the effects of mirror back scattering. This model can be used to
also describe the situation of two membranes that both interact with the cavity
fields. This may be interesting for future work on synchronization of distant
oscillators that are coupled by intracavity light fields.",1608.02799v1
2016-08-11,Decay of geodesic acoustic modes due to the combined action of phase mixing and Landau damping,"Geodesic acoustic modes (GAMs) are oscillations of the electric field whose
importance in tokamak plasmas is due to their role in the regulation of
turbulence. The linear collisionless damping of GAMs is investigated here by
means of analytical theory and numerical simulations with the global
gyrokinetic particle-in-cell code ORB5. The combined effect of the phase mixing
and Landau damping is found to quickly redistribute the GAM energy in
phase-space, due to the synergy of the finite orbit width of the passing ions
and the cascade in wave number given by the phase mixing. When plasma
parameters characteristic of realistic tokamak profiles are considered, the GAM
decay time is found to be an order of magnitude lower than the decay due to the
Landau damping alone, and in some cases of the same order of magnitude of the
characteristic GAM drive time due to the nonlinear interaction with an ITG
mode. In particular, the radial mode structure evolution in time is
investigated here and reproduced quantitatively by means of a dedicated initial
value code and diagnostics.",1608.03447v1
2016-12-13,Continuous-variable entanglement generated with a hybrid PT-symmetric system,"We study a proposal of generating macroscopic continuous-variable
entanglement with two coupled waveguides respectively carrying optical damping
and optical gain. Moreover, a squeezing element is added into one or both
waveguides. We show that quantum noise effect existing in the process is
essential to the degree of the generated entanglement. It will totally
eliminate the entanglement in the setup of adding the squeezing element into
the waveguide filled with optical damping material, but will not completely
damp the entanglement to zero in the other configurations of having the
squeezing element in the gain medium or in both gain and damping medium. The
degree of the generated continuous-variable entanglement is irrelevant to the
intensities of the input light in coherent states. Moreover, the relations
between the entanglement and system parameters are illustrated in terms of the
dynamical evolutions of the created continuous-variable entanglement.",1612.03996v2
2017-06-09,Effect of oxygen plasma on nanomechanical silicon nitride resonators,"Precise control of tensile stress and intrinsic damping is crucial for the
optimal design of nanomechanical systems for sensor applications and quantum
optomechanics in particular. In this letter we study the in uence of oxygen
plasma on the tensile stress and intrinsic damping of nanomechanical silicon
nitride resonators. Oxygen plasma treatments are common steps in micro and
nanofabrication. We show that oxygen plasma of only a few minutes oxidizes the
silicon nitride surface, creating several nanometer thick silicon dioxide
layers with a compressive stress of 1.30(16)GPa. Such oxide layers can cause a
reduction of the e ective tensile stress of a 50 nm thick stoichiometric
silicon nitride membrane by almost 50%. Additionally, intrinsic damping
linearly increases with the silicon dioxide lm thickness. An oxide layer of
1.5nm grown in just 10s in a 50W oxygen plasma almost doubled the intrinsic
damping. The oxide surface layer can be e ciently removed in bu ered HF.",1706.02957v1
2017-06-11,Absorbing boundary layers for spin wave micromagnetics,"Micromagnetic simulations are used to investigate the effects of different
absorbing boundary layers (ABLs) on spin waves (SWs) reflected from the edges
of a magnetic nano-structure. We define the conditions that a suitable ABL must
fulfill and compare the performance of abrupt, linear, polynomial and tan
hyperbolic damping profiles in the ABL. We first consider normal incidence in a
permalloy stripe and propose a transmission line model to quantify reflections
and calculate the loss introduced into the stripe due to the ABL. We find that
a parabolic damping profile absorbs the SW energy efficiently and has a low
reflection coefficient, thus performing much better than the commonly used
abrupt damping profile. We then investigated SWs that are obliquely incident at
26.6, 45 and 63.4 degrees on the edge of a yttrium-iron-garnet film. The
parabolic damping profile again performs efficiently by showing a high SW
energy transfer to the ABL and a low reflected SW amplitude.",1706.03325v1
2017-07-03,Quantum behaviour of pumped and damped triangular Bose Hubbard systems,"We propose and analyse analogs of optical cavities for atoms using three-well
Bose-Hubbard models with pumping and losses. We consider triangular
configurations. With one well pumped and one damped, we find that both the
mean-field dynamics and the quantum statistics show a quantitative dependence
on the choice of damped well. The systems we analyse remain far from
equilibrium, preserving good coherence between the wells in the steady-state.
We find quadrature squeezing and mode entanglement for some parameter regimes
and demonstrate that the trimer with pumping and damping at the same well is
the stronger option for producing non-classical states. Due to recent
experimental advances, it should be possible to demonstrate the effects we
investigate and predict.",1707.01000v1
2017-07-06,Damping optimization of parameter dependent mechanical systems by rational interpolation,"We consider an optimization problem related to semi-active damping of
vibrating systems. The main problem is to determine the best damping matrix
able to minimize influence of the input on the output of the system. We use a
minimization criteria based on the $\mathcal{H}_2$ system norm.
  The objective function is non-convex and the associated optimization problem
typically requires a large number of objective function evaluations. We propose
an optimization approach that calculates `interpolatory' reduced order models,
allowing for significant acceleration of the optimization process.
  In our approach, we use parametric model reduction (PMOR) based on the
Iterative Rational Krylov Algorithm, which ensures good approximations relative
to the $\mathcal{H}_2$ system norm, aligning well with the underlying damping
design objectives. For the parameter sampling that occurs within each PMOR
cycle, we consider approaches with predetermined sampling and approaches using
adaptive sampling, and each of these approaches may be combined with three
possible strategies for internal reduction. In order to preserve important
system properties, we maintain second-order structure, which through the use of
modal coordinates, allows for very efficient implementation.
  The methodology proposed here provides a significant acceleration of the
optimization process; the gain in efficiency is illustrated in numerical
experiments.",1707.01789v1
2017-07-08,Nonlinear dynamics of damped DNA systems with long-range interactions,"We investigate the nonlinear dynamics of a damped Peyrard-Bishop DNA model
taking into account long-range interactions with distance dependence |l|^-s on
the elastic coupling constant between different DNA base pairs. Considering
both Stokes and long-range hydrodynamical damping forces, we use the discrete
difference operator technique and show in the short wavelength modes that the
lattice equation can be governed by the complex Ginzburg-Landau equation. We
found analytically that the technique leads to the correct expression for the
breather soliton parameters. We found that the viscosity makes the amplitude of
the breather to damp out. We compare the approximate analytic results with
numerical simulations for the value s = 3 (dipole-dipole interactions).",1707.02425v1
2017-10-09,Time-dependent propagation speed vs strong damping for degenerate linear hyperbolic equations,"We consider a degenerate abstract wave equation with a time-dependent
propagation speed. We investigate the influence of a strong dissipation, namely
a friction term that depends on a power of the elastic operator.
  We discover a threshold effect. If the propagation speed is regular enough,
then the damping prevails, and therefore the initial value problem is
well-posed in Sobolev spaces. Solutions also exhibit a regularizing effect
analogous to parabolic problems. As expected, the stronger is the damping, the
lower is the required regularity.
  On the contrary, if the propagation speed is not regular enough, there are
examples where the damping is ineffective, and the dissipative equation behaves
as the non-dissipative one.",1710.03602v1
2017-10-17,Entropic uncertainty relation under quantum channels with memory,"Recently, Xu et al. [Phys. Rev. A 86, 012113(2012)] explored the behavior of
the entropic uncertainty relation under the influence of local unital and
nonunital noisy channels for a class of Bell-diagonal states. We here reform
their results and investigate the entropic uncertainty relation under the
influence of unital and nonunital noisy channels with memory. Different types
of noisy channels with memory, such as amplitude damping channel(nonunitary),
phase-damping and depolarizing channels(unitary) have been taken into account.
Some analytical or numerical results are presented. The effect of channels with
memory on dynamics of the entropic uncertainties (or their lower bounds) has
been discussed in detail. Compare with previous results, our results show that,
the entropic uncertainties (or their lower bounds) subjecting to amplitude
damping channel with memory will be reduced at first and then be lifted with
the memory coefficient of channel $\mu$ increasing, however they will be only
reduced under phase-damping and depolarizing channels with memory. Especially,
in the limit of $\mu\rightarrow1$, the entropic uncertainties (or their lower
bounds) could be well protected and immune to decoherence of channle. Moreover,
the mechanism behind these phenomena are also explored by using the purity of
state.",1710.06344v1
2017-10-31,Improving mechanical sensor performance through larger damping,"Mechanical resonances are used in a wide variety of devices; from smart phone
accelerometers to computer clocks and from wireless communication filters to
atomic force microscope sensors. Frequency stability, a critical performance
metric, is generally assumed to be tantamount to resonance quality factor (the
inverse of the linewidth and of the damping). Here we show that frequency
stability of resonant nanomechanical sensors can generally be made independent
of quality factor. At high bandwidths, we show that quality factor reduction is
completely mitigated by increases in signal to noise ratio. At low bandwidths,
strikingly, increased damping leads to better stability and sensor resolution,
with improvement proportional to damping. We confirm the findings by
demonstrating temperature resolution of 50 \mu K at 200 Hz bandwidth. These
results open the door for high performance ultrasensitive resonant sensors in
gaseous or liquid environments, single cell nanocalorimetry, nanoscale gas
chromatography, and atmospheric pressure nanoscale mass spectrometry.",1710.11280v1
2017-12-04,DAMPE Electron-Positron Excess in Leptophilic $Z'$ model,"Recently the DArk Matter Particle Explorer (DAMPE) has reported an excess in
the electron-positron flux of the cosmic rays which is interpreted as a dark
matter particle with the mass about $1.5$ TeV. We come up with a leptophilic
$Z'$ scenario including a Dirac fermion dark matter candidate which beside
explaining the observed DAMPE excess, is able to pass various
experimental/observational constraints including the relic density value from
the WMAP/Planck, the invisible Higgs decay bound at the LHC, the LEP bounds in
electron-positron scattering, the muon anomalous magnetic moment constraint,
Fermi-LAT data, and finally the direct detection experiment limits from the
XENON1t/LUX. By computing the electron-positron flux produced from a dark
matter with the mass about $1.5$ TeV we show that the model predicts the peak
observed by the DAMPE.",1712.01239v4
2017-12-06,Confronting the DAMPE Excess with the Scotogenic Type-II Seesaw Model,"The DArk Matter Particle Explorer (DAMPE) has observed a tentative peak at
$E\sim1.4~\TeV$ in the cosmic-ray electron spectrum. In this paper, we
interpret this excess in the scotogenic type-II seesaw model. This model
extends the canonical type-II seesaw model with dark matter (DM) candidates and
a loop-induced vacuum expectation value of the triplet scalars, $v_\Delta$,
resulting in small neutrino masses naturally even for TeV scale triplet
scalars. Assuming a nearby DM subhalo, the DAMPE excess can be explained by DM
annihilating into a pair of triplet scalars which subsequently decay to charged
lepton final states. Spectrum fitting of the DAMPE excess indicates it
potentially favors the inverted neutrino mass hierarchy. We also discuss how to
evade associated neutrino flux in our model.",1712.02021v3
2018-09-04,Separation of the two-magnon scattering contribution to damping for the determination of the spin mixing conductance,"We present angle dependent measurements of the damping properties of
epitaxial Fe layers with MgO, Al and Pt capping layers. Based on the
preferential distribution of lattice defects following the crystal symmetry, we
make use of a model of the defect density to separate the contribution of
two-magnon scattering to the damping from the isotropic contribution
originating in the spin pumping effect, the viscous Gilbert damping and the
magnetic proximity effect. The separation of the two-magnon contribution, which
depends strongly on the defect density, allows for the measurement of a value
of the effective spin mixing conductance which is closer to the value
exclusively due to spin pumping. The influence of the defect density for
bilayers systems due to the different capping layers and to the unavoidable
spread in defect density from sample to sample is thus removed. This shows the
potential of studying spin pumping phenomena in fully ordered systems in which
this separation is possible, contrary to polycrystalline or amorphous metallic
thin films.",1809.01042v1
2018-09-26,Permutation-invariant constant-excitation quantum codes for amplitude damping,"The increasing interest in using quantum error correcting codes in practical
devices has heightened the need for designing quantum error correcting codes
that can correct against specialized errors, such as that of amplitude damping
errors which model photon loss. Although considerable research has been devoted
to quantum error correcting codes for amplitude damping, not so much attention
has been paid to having these codes simultaneously lie within the decoherence
free subspace of their underlying physical system. One common physical system
comprises of quantum harmonic oscillators, and constant-excitation quantum
codes can be naturally stabilized within them. The purpose of this paper is to
give constant-excitation quantum codes that not only correct amplitude damping
errors, but are also immune against permutations of their underlying modes. To
construct such quantum codes, we use the nullspace of a specially constructed
matrix based on integer partitions.",1809.09801v4
2018-09-30,Critical behavior of the damping rate of GHz acoustic phonons in SrTiO3 at the antiferrodistortive phase transition measured by time- and frequency-resolved Brillouin scattering,"We determine the temperature dependent damping rate of longitudinal acoustic
phonons in SrTiO3 using frequency domain Brillouin scattering and time domain
Brillouin scattering. We investigate samples with (La,Sr)MnO3 and SrRuO3
capping layers, which result in compressive or tensile strain at the layer -
substrate interface, respectively. The different strain states lead to dif-
ferent domain structures in SrTiO3 that extend into the bulk of the SrTiO3
substrates and strongly affect the phonon propagation. Our experiments show
that the damping rate of acoustic phonons in the interfacial STO layer depends
strongly on the sample temperature and strain induced do- main structure. We
also show that the damping rate as function of temperature exhibits a critical
behavior close to the cubic-to-tetragonal phase transition of SrTiO3.",1810.00381v1
2019-07-01,Probing superfluid $^4\mathrm{He}$ with high-frequency nanomechanical resonators down to $\mathrm{mK}$ temperatures,"Superfluids, such as superfluid $^3\mathrm{He}$ and $^4\mathrm{He}$, exhibit
a broad range of quantum phenomena and excitations which are unique to these
systems. Nanoscale mechanical resonators are sensitive and versatile force
detectors with the ability to operate over many orders of magnitude in damping.
Using nanomechanical-doubly clamped beams of extremely high quality factors
($Q>10^6$), we probe superfluid $^4\mathrm{He}$ from the superfluid transition
temperature down to $\mathrm{mK}$ temperatures at frequencies up to $11.6 \,
\mathrm{MHz}$. Our studies show that nanobeam damping is dominated by
hydrodynamic viscosity of the normal component of $^4\mathrm{He}$ above
$1\,\mathrm{K}$. In the temperature range $0.3-0.8\,\mathrm{K}$, the ballistic
quasiparticles (phonons and rotons) determine the beams' behavior. At lower
temperatures, damping saturates and is determined either by magnetomotive
losses or acoustic emission into helium. It is remarkable that all these
distinct regimes can be extracted with just a single device, despite damping
changing over six orders of magnitude.",1907.00970v1
2019-07-10,The superior role of the Gilbert damping on the signal-to-noise ratio in heat-assisted magnetic recording,"In magnetic recording the signal-to-noise ratio (SNR) is a good indicator for
the quality of written bits. However, a priori it is not clear which parameters
have the strongest influence on the SNR. In this work, we investigate the role
of the Gilbert damping on the SNR. Grains consisting of FePt like hard magnetic
material with two different grain sizes $d_1=5\,$nm and $d_2=7\,$nm are
considered and simulations of heat-assisted magnetic recording (HAMR) are
performed with the atomistic simulation program VAMPIRE. The simulations
display that the SNR saturates for damping constants larger or equal than 0.1.
Additionally, we can show that the Gilbert damping together with the bit length
have a major effect on the SNR whereas other write head and material parameters
only have a minor relevance on the SNR.",1907.04577v2
2019-07-15,Asymptotic profiles of solutions for regularity-loss type generalized thermoelastic plate equations and their applications,"In this paper, we consider generalized thermoelastic plate equations with
Fourier's law of heat conduction. By introducing a threshold for decay
properties of regularity-loss, we investigate decay estimates of solutions
with/without regularity-loss in a framework of weighted $L^1$ spaces.
Furthermore, asymptotic profiles of solutions are obtained by using
representations of solutions in the Fourier space, which are derived by
employing WKB analysis. Next, we study generalized thermoelastic plate
equations with additional structural damping, and analysis the influence of
structural damping on decay properties and asymptotic profiles of solutions. We
find that the regularity-loss structure is destroyed by structural damping.
Finally, we give some applications of our results on thermoelastic plate
equations and damped Moore-Gibson-Thompson equation.",1907.06344v1
2019-07-21,Critical Thresholds in One Dimensional Damped Euler-Poisson Systems,"This paper is concerned with the critical threshold phenomenon for one
dimensional damped, pressureless Euler-Poisson equations with electric force
induced by a constant background, originally studied in [S. Engelberg and H.
Liu and E. Tadmor, Indiana Univ. Math. J., 50:109--157, 2001]. A simple
transformation is used to linearize the characteristic system of equations,
which allows us to study the geometrical structure of critical threshold curves
for three damping cases: overdamped, underdamped and borderline damped through
phase plane analysis. We also derive the explicit form of these critical
curves. These sharp results state that if the initial data is within the
threshold region, the solution will remain smooth for all time, otherwise it
will have a finite time breakdown. Finally, we apply these general results to
identify critical thresholds for a non-local system subjected to initial data
on the whole line.",1907.09039v1
2019-07-23,Ignatyuk damping factor: A semiclassical formula,"Data on nuclear level densities extracted from transmission data or gamma
energy spectrum store the basic statistical information about nuclei at various
temperatures. Generally this extracted data goes through model fitting using
computer codes like CASCADE. However, recently established semiclassical
methods involving no adjustable parameters to determine the level density
parameter for magic and semi-magic nuclei give a good agreement with the
experimental values. One of the popular ways to paramaterize the level density
parameter which includes the shell effects and its damping was given by
Ignatyuk. This damping factor is usually fitted from the experimental data on
nuclear level density and it comes around 0.05 $MeV^{-1}$. In this work we
calculate the Ignatyuk damping factor for various nuclei using semiclassical
methods.",1907.09770v1
2019-09-21,Resonant absorption of kink oscillations in coronal flux tubes with continuous magnetic twist,"There are observational evidences for the existence of twisted magnetic field
in the solar corona. Here, we have investigated resonant damping of the
magnetohydrodynamic (MHD) kink waves in magnetic flux tubes. A realistic model
of the tube with continuous magnetic twist and radially inhomogeneous density
profile has been considered. We have obtained the dispersion relation of the
kink wave using the solution to the linear MHD equations outside the density
inhomogeneity and the appropriate connection formula to the solutions across
the thin transitional boundary layer. The dependence of the oscillation
frequency and damping rate of the waves on the twist parameter and longitudinal
wavenumber has been investigated. For the flux tube parameters considered in
this paper, we obtain rapid damping of the kink waves comparable to the
observations. In order to justify this rapid damping, depending on the sign of
the azimuthal kink mode number, $m=+1$ or $m=-1$, the background magnetic field
must have left handed or right handed twisted profile, respectively. For the
model considered here, the resonant absorption occurs only when the twist
parameter is in a range specified by the density contrast.",1909.09787v1
2019-10-22,Controlled nonlinear magnetic damping in spin-Hall nano-devices,"Large-amplitude magnetization dynamics is substantially more complex compared
to the low-amplitude linear regime, due to the inevitable emergence of
nonlinearities. One of the fundamental nonlinear phenomena is the nonlinear
damping enhancement, which imposes strict limitations on the operation and
efficiency of magnetic nanodevices. In particular, nonlinear damping prevents
excitation of coherent magnetization auto-oscillations driven by the injection
of spin current into spatially extended magnetic regions. Here, we propose and
experimentally demonstrate that nonlinear damping can be controlled by the
ellipticity of magnetization precession. By balancing different contributions
to anisotropy, we minimize the ellipticity and achieve coherent magnetization
oscillations driven by spatially extended spin current injection into a
microscopic magnetic disk. Our results provide a novel route for the
implementation of efficient active spintronic and magnonic devices driven by
spin current.",1910.09801v1
2019-10-24,Spin waves in ferromagnetic thin films,"A spin wave is the disturbance of intrinsic spin order in magnetic materials.
In this paper, a spin wave in the Landau-Lifshitz-Gilbert equation is obtained
based on the assumption that the spin wave maintains its shape while it
propagates at a constant velocity. Our main findings include: (1) in the
absence of Gilbert damping, the spin wave propagates at a constant velocity
with the increment proportional to the strength of the magnetic field; (2) in
the absence of magnetic field, at a given time the spin wave converges
exponentially fast to its initial profile as the damping parameter goes to zero
and in the long time the relaxation dynamics of the spin wave converges
exponentially fast to the easy-axis direction with the exponent proportional to
the damping parameter; (3) in the presence of both Gilbert damping and magnetic
field, the spin wave converges to the easy-axis direction exponentially fast at
a small timescale while propagates at a constant velocity beyond that. These
provides a comprehensive understanding of spin waves in ferromagnetic
materials.",1910.11200v1
2019-10-24,The lifespan of solutions of semilinear wave equations with the scale-invariant damping in two space dimensions,"In this paper, we study the initial value problem for semilinear wave
equations with the time-dependent and scale-invariant damping in two
dimensions. Similarly to the one dimensional case by Kato, Takamura and Wakasa
in 2019, we obtain the lifespan estimates of the solution for a special
constant in the damping term, which are classified by total integral of the sum
of the initial position and speed. The key fact is that, only in two space
dimensions, such a special constant in the damping term is a threshold between
""wave-like"" domain and ""heat-like"" domain. As a result, we obtain a new type of
estimate especially for the critical exponent.",1910.11692v2
2020-01-31,Dynamo in weakly collisional nonmagnetized plasmas impeded by Landau damping of magnetic fields,"We perform fully kinetic simulations of flows known to produce dynamo in
magnetohydrodynamics (MHD), considering scenarios with low Reynolds number and
high magnetic Prandtl number, relevant for galaxy cluster scale fluctuation
dynamos. We find that Landau damping on the electrons leads to a rapid decay of
magnetic perturbations, impeding the dynamo. This collisionless damping process
operates on spatial scales where electrons are nonmagnetized, reducing the
range of scales where the magnetic field grows in high magnetic Prandtl number
fluctuation dynamos. When electrons are not magnetized down to the resistive
scale, the magnetic energy spectrum is expected to be limited by the scale
corresponding to magnetic Landau damping or, if smaller, the electron
gyroradius scale, instead of the resistive scale. In simulations we thus
observe decaying magnetic fields where resistive MHD would predict a dynamo.",2001.11929v2
2020-04-23,Damping of gravitational waves in 2-2-holes,"A 2-2-hole is an explicit realization of a horizonless object that can still
very closely resemble a BH. An ordinary relativistic gas can serve as the
matter source for the 2-2-hole solution of quadratic gravity, and this leads to
a calculable area-law entropy. Here we show that it also leads to an estimate
of the damping of a gravitational wave as it travels to the center of the
2-2-hole and back out again. We identify two frequency dependent effects that
greatly diminish the damping. Spinning 2-2-hole solutions are not known, but we
are still able to consider some spin dependent effects. The frequency and spin
dependence of the damping helps to determine the possible echo resonance signal
from the rotating remnants of merger events. It also controls the fate of the
ergoregion instability.",2004.11285v3
2017-04-30,Comparison of dynamic mechanical properties of non-superheated and superheated A357 alloys,"The influence of superheat treatment on the microstructure and dynamic
mechanical properties of A357 alloys has been investigated. The study of
microstructure was performed by the optical microscope. Dynamic mechanical
properties (storage modulus, loss modulus, and damping capacity) were measured
by the dynamic mechanical analyzer (DMA). Microstructure showed coarser and
angular eutectic Si particles with larger {\alpha}-Al dendrites in the
non-superheated A357 alloy. In contrast, finer and rounded eutectic Si
particles together with smaller and preferred oriented {\alpha}-Al dendrites
have been observed in the superheated A357 alloy. Dynamic mechanical properties
showed an increasing trend of loss modulus and damping capacity meanwhile a
decreasing trend of storage modulus at elevated temperatures for superheated
and non-superheated A357 alloys. The high damping capacity of superheated A357
has been ascribed to the grain boundary damping at elevated temperatures.",1705.00350v1
2017-05-09,Low spin wave damping in the insulating chiral magnet Cu$_{2}$OSeO$_{3}$,"Chiral magnets with topologically nontrivial spin order such as Skyrmions
have generated enormous interest in both fundamental and applied sciences. We
report broadband microwave spectroscopy performed on the insulating chiral
ferrimagnet Cu$_{2}$OSeO$_{3}$. For the damping of magnetization dynamics we
find a remarkably small Gilbert damping parameter of about $1\times10^{-4}$ at
5 K. This value is only a factor of 4 larger than the one reported for the best
insulating ferrimagnet yttrium iron garnet. We detect a series of sharp
resonances and attribute them to confined spin waves in the mm-sized samples.
Considering the small damping, insulating chiral magnets turn out to be
promising candidates when exploring non-collinear spin structures for high
frequency applications.",1705.03416v1
2017-05-19,Improving two - qubit state teleportation affected by amplitude damping noise based on choosing appropriate quantum channel,"We consider two qubit teleportation via quantum channel affected by amplitude
damping noise. Addressing the same problem, X. Hu, Y. Gu, Q. Gong and G. Guo
[Phys. Rev. A 81, 054302, (2010)] recently showed that in presence of noise,
subjecting more qubits in quantum channel to amplitude damping can increase the
fidelity of teleportation protocol. However, in this paper, by making some
adjustments on quantum channel, we obtain teleportation fidelity which is even
higher than one in the case of X. Hu et al. Moreover, our strategy is simpler
than quantum distillation and compared to using weak measurement, it is
deterministic. Furthermore, explicit analysis of fidelity is provided, we show
that in general, choosing appropriate quantum channel enhances the ability of
teleportation better and negates the fact that more amplitude damping noise
more quality.",1705.07064v2
2017-05-27,Charge reconstruction study of the DAMPE Silicon-Tungsten Tracker with ion beams,"The DArk Matter Particle Explorer (DAMPE) is one of the four satellites
within Strategic Pioneer Research Program in Space Science of the Chinese
Academy of Science (CAS). DAMPE can detect electrons, photons in a wide energy
range (5 GeV to 10 TeV) and ions up to iron (100GeV to 100 TeV).
Silicon-Tungsten Tracker (STK) is one of the four subdetectors in DAMPE,
providing photon-electron conversion, track reconstruction and charge
identification for ions. Ion beam test was carried out in CERN with 60GeV/u
Lead primary beams. Charge reconstruction and charge resolution of STK
detectors were investigated.",1705.09791v1
2017-09-01,Scaling of the Rashba spin-orbit torque in magnetic domain walls,"Spin-orbit torque in magnetic domain walls was investigated by solving the
Pauli-Schr\""{o}dinger equation for the itinerant electrons. The Rashba
interaction considered is derived from the violation of inversion symmetry at
interfaces between ferromagnets and heavy metals. In equilibrium, the Rashba
spin-orbit interaction gives rise to a torque corresponding to the
Dzyaloshinskii-Moriya interaction. When there is a current flowing, the
spin-orbit torque experienced by the itinerant electrons in short domain walls
has both field-like and damping-like components. However, when the domain wall
width is increased, the damping-like component, which is the counterpart of the
non-adiabatic spin transfer torque, decreases rapidly at the domain wall
center. In contrast to the non-adiabatic spin transfer torque, the damping-like
spin-orbit torque does not approach to zero far away from the domain wall
center, even in the adiabatic limit. The scattering of spin-up and spin-down
wave functions, which is caused by the Rashba spin-orbit interaction and the
spatial variation of magnetization profile in the domain wall, gives rise to
the finite damping-like spin-orbit torque.",1709.00187v3
2017-09-12,Temperature effects on MIPs in the BGO calorimeters of DAMPE,"In this paper, we presented a study of temperature effects on BGO
calorimeters using proton MIP's collected in the first year operation of DAMPE.
By directly comparing MIP calibration constants used by DAMPE data production
pipe line, we found an experimental relation between temperature and signal
amplitudes of each BGO bar: a general deviation of -1.162%/$^{\circ}$C,and
-0.47%/$^{\circ}$C to -1.60%/$^{\circ}$C statistically for each detector
element. During 2016, DAMPE's temperature changed by about 7 degrees due to
solar elevation angle and the corresponding energy scale bias is about 8%. By
frequent MIP calibration operation, this kind of bias is eliminated to an
acceptable value.",1709.03735v2
2017-09-14,Intrinsic Damping Phenomena from Quantum to Classical Magnets:An ab-initio Study of Gilbert Damping in Pt/Co Bilayer,"A fully quantum mechanical description of the precessional damping of Pt/Co
bilayer is presented in the framework of the Keldysh Green function approach
using {\it ab initio} electronic structure calculations. In contrast to
previous calculations of classical Gilbert damping ($\alpha_{GD}$), we
demonstrate that $\alpha_{GD}$ in the quantum case does not diverge in the
ballistic regime due to the finite size of the total spin, $S$. In the limit of
$S\rightarrow\infty$ we show that the formalism recovers the torque correlation
expression for $\alpha_{GD}$ which we decompose into spin-pumping and
spin-orbital torque correlation contributions. The formalism is generalized to
take into account a self consistently determined dephasing mechanism which
preserves the conservation laws and allows the investigation of the effect of
disorder. The dependence of $\alpha_{GD}$ on Pt thickness and disorder strength
is calculated and the spin diffusion length of Pt and spin mixing conductance
of the bilayer are determined and compared with experiments.",1709.04911v2
2017-09-28,Universal and approximate relations for the gravitational-wave damping timescale of $f$-modes in neutron stars,"Existing estimates of the gravitational-wave damping timescale of the
dominant quadrupole oscillation mode in the case of rapidly rotating stars are
based on using a Newtonian estimate for the energy of the mode, in combination
with the lowest-order post-Newtonian quadrupole formula for estimating the
gravitational-wave luminosity. We investigate a number of other choices for
estimating the gravitational-wave damping timescale in the nonrotating limit
and construct a highly accurate, empirically corrected formula that has a
maximum relative error of only 3% with respect to the perturbative result in
full general relativity. The expressions involved are sufficiently general to
be extended to the case of rapidly rotating stars. We also present a new
higher-order empirical relation for the gravitational-wave damping timescale of
quadrupole oscillations that is accurate in the whole range of expected values
for the compactness of neutron stars, without the need for involving the moment
of inertia.",1709.10067v2
2017-11-30,The electron-flavored Z'-portal dark matter and the DAMPE cosmic ray excess,"The DAMPE experiment has recently reported strong indications for the
existence of an excess of high-energy electrons and positrons. If interpreted
in terms of the annihilation of dark matter, the DAMPE result restricts the
dark matter mass and possible annihilation channels to a few case. In this
paper we explain the DAMPE result with the electron-flavored $Z^\prime$-portal
fermionic dark matter. We show that the Dirac dark matter scenario is promising
to explain the excess via the process $\bar \chi \chi \to\mathbf{Z}'\to \bar e
e$. The reduced annihilation cross section is limited in a range of
$10^{-26}\sim 10^{-24}~{\rm cm^3 s^{-1}}$ to interpret the excess.",1711.11182v2
2018-03-03,Universal stabilization of single-qubit states using a tunable coupler,"We theoretically analyze a scheme for fast stabilization of arbitrary qubit
states with high fidelities, extending a protocol recently demonstrated
experimentally [Lu et al., Phys. Rev. Lett. 119, 150502 (2017)]. That
experiment utilized red and blue sideband transitions in a system composed of a
fluxonium qubit, a low-Q LC-oscillator, and a coupler enabling us to tune the
interaction between them. Under parametric modulations of the coupling
strength, the qubit can be steered into any desired pure or mixed single-qubit
state. For realistic circuit parameters, we predict that stabilization can be
achieved within 100 ns. By varying the ratio between the oscillator's damping
rate and the effective qubit-oscillator coupling strength, we can switch
between under-damped, critically-damped, and over-damped stabilization and find
optimal working points. We further analyze the effect of thermal fluctuations
and show that the stabilization scheme remains robust for realistic
temperatures.",1803.01079v3
2018-06-01,"Fluctuation-damping of isolated, oscillating Bose-Einstein condensates","Experiments on the nonequilibrium dynamics of an isolated Bose-Einstein
condensate (BEC) in a magnetic double-well trap exhibit a puzzling divergence:
While some show dissipation-free Josephson oscillations, others find strong
damping. Such damping in isolated BECs cannot be understood on the level of the
coherent Gross-Pitaevskii dynamics. Using the Keldysh functional-integral
formalism, we describe the time-dependent system dynamics by means of a
multi-mode BEC coupled to fluctuations (single-particle excitations) beyond the
Gross-Pitaevskii saddle point. We find that the Josephson oscillations excite
an excess of fluctuations when the effective Josephson frequency,
$\tilde{\omega}_J$, is in resonance with the effective fluctuation energy,
$\tilde{\varepsilon}_m$, where both, $\tilde{\omega}_J$ and
$\tilde{\varepsilon}_m$, are strongly renormalized with respect to their
noninteracting values. Evaluating and using the model parameters for the
respective experiments describes quantitatively the presence or absence of
damping.",1806.00376v2
2018-06-05,Decoherence assisted spin squeezing generation in superposition of tripartite GHZ and W states,"In the present paper, we study spin squeezing under decoherence in the
superposition of tripartite maximally entangled GHZ and W states. Here we use
amplitude damping, phase damping and depolarisation channel. We have
investigated the dynamics of spin squeezing with the interplay of superposition
and decoherence parameters with different directions of the mean spin vector.
We have found the mixture of GHZ and W states is robust against spin squeezing
generation for amplitude damping and phase damping channels for certain
directions of the mean spin vector. However, the depolarisation channel
performs well for spin squeezing generation and generates permanent spin
squeezing in the superposition of GHZ and W states.",1806.01730v1
2018-07-31,Dark Matter Particle Explorer observations of high-energy cosmic ray electrons plus positrons and their physical implications,"The DArk Matter Particle Explorer (DAMPE) is a satellite-borne, high-energy
particle and $\gamma$-ray detector, which is dedicated to indirectly detecting
particle dark matter and studying high-energy astrophysics. The first results
about precise measurement of the cosmic ray electron plus positron spectrum
between 25 GeV and 4.6 TeV were published recently. The DAMPE spectrum reveals
an interesting spectral softening around $0.9$ TeV and a tentative peak around
$1.4$ TeV. These results have inspired extensive discussion. The detector of
DAMPE, the data analysis, and the first results are introduced. In particular,
the physical interpretations of the DAMPE data are reviewed.",1807.11638v1
2018-08-08,A Hybrid Dynamic-regenerative Damping Scheme for Energy Regeneration in Variable Impedance Actuators,"Increasing research efforts have been made to improve the energy efficiency
of variable impedance actuators (VIAs) through reduction of energy consumption.
However, the harvesting of dissipated energy in such systems remains
underexplored. This study proposes a novel variable damping module design
enabling energy regeneration in VIAs by exploiting the regenerative braking
effect of DC motors. The proposed damping module uses four switches to combine
regenerative and dynamic braking, in a hybrid approach that enables energy
regeneration without reduction in the range of damping achievable. Numerical
simulations and a physical experiment are presented in which the proposed
module shows an optimal trade-off between task performance and energy
efficiency.",1808.03143v1
2018-08-15,$L^1$ estimates for oscillating integrals and their applications to semi-linear models with $σ$-evolution like structural damping,"The present paper is a continuation of our recent paper \cite{DaoReissig}. We
will consider the following Cauchy problems for semi-linear structurally damped
$\sigma$-evolution models: \begin{equation*} u_{tt}+ (-\Delta)^\sigma u+ \mu
(-\Delta)^\delta u_t = f(u,u_t),\, u(0,x)= u_0(x),\, u_t(0,x)=u_1(x)
\end{equation*} with $\sigma \ge 1$, $\mu>0$ and $\delta \in
(\frac{\sigma}{2},\sigma]$. Our aim is to study two main models including
$\sigma$-evolution models with structural damping $\delta \in
(\frac{\sigma}{2},\sigma)$ and those with visco-elastic damping
$\delta=\sigma$. Here the function $f(u,u_t)$ stands for power nonlinearities
$|u|^{p}$ and $|u_t|^{p}$ with a given number $p>1$. We are interested in
investigating the global (in time) existence of small data solutions to the
above semi-linear models from suitable spaces basing on $L^q$ space by assuming
additional $L^{m}$ regularity on the initial data, with $q\in (1,\infty)$ and
$m\in [1,q)$.",1808.05484v2
2018-12-04,Atmospheric oscillations provide simultaneous measurement of neutron star mass and radius,"Neutron stars with near-Eddington observable luminosities were shown to
harbor levitating atmospheres, suspended above their surface. We report a new
method to simultaneously measure the mass and radius of a neutron star based on
oscillations of such atmospheres. In this paper, we present an analytic
derivation of a family of relativistic, oscillatory, spherically symmetric
eigenmodes of the optically and geometrically thin levitating atmospheres,
including the damping effects induced by the radiation drag. We discover
characteristic maxima in the frequencies of the damped oscillations and show
that using the frequency maxima, one can estimate mass and radius of the
neutron star, given the observed frequency and the corresponding luminosity of
the star during the X-ray burst. Thus, our model provides a new way to probe
the stellar parameters. We also show that the ratio of any two undamped
eigenfrequencies depends only on the adiabatic index of the atmosphere, while
for the damped eigenfrequencies, this ratio varies with the luminosity. The
damping coefficient is independent of the mode number of the oscillations.
Signatures of these atmospheres' dynamics will be reflected in the source's
X-ray light curves.",1812.01299v2
2018-12-04,Spin transport in a magnetic insulator with zero effective damping,"Applications based on spin currents strongly profit from the control and
reduction of their effective damping and their transport properties. We here
experimentally observe magnon mediated transport of spin (angular) momentum
through a 13.4 nm thin yttrium iron garnet film with full control of the
magnetic damping via spin-orbit torque. Above a critical spin-orbit torque, the
fully compensated damping manifests itself as an increase of magnon
conductivity by almost two orders of magnitude. We compare our results to
theoretical expectations based on recently predicted current induced magnon
condensates and discuss other possible origins of the observed critical
behaviour.",1812.01334v3
2019-01-10,Data-Driven Online Optimization for Enhancing Power System Oscillation Damping,"This paper reports an initial work on power system oscillation damping
improvement using a data-driven online optimization method. An online
oscillation damping optimization mod-el is proposed and formulated in a form
solvable by the data-driven method. Key issues in the online optimization
procedures, including the damping sensitivity identification method, its
compatibility with the dispatch plans, as well as other practical issues in
real large-scale system are discussed. Simulation results based on the 2-area
4-machine system, and the NETS-NYPS 68-bus system verify the feasibility and
efficiency of the proposed method. The results also show the capability of the
proposed method to bridge the gap between online data analysis and complex
optimization for power system dynamics.",1901.03167v2
2019-01-13,Nonexistence of global solutions for a weakly coupled system of semilinear damped wave equations in the scattering case with mixed nonlinear terms,"In this paper we consider the blow-up of solutions to a weakly coupled system
of semilinear damped wave equations in the scattering case with nonlinearities
of mixed type, namely, in one equation a power nonlinearity and in the other a
semilinear term of derivative type. The proof of the blow-up results is based
on an iteration argument. As expected, due to the assumptions on the
coefficients of the damping terms, we find as critical curve in the p-q plane
for the pair of exponents (p,q) in the nonlinear terms the same one found by
Hidano-Yokoyama and, recently, by Ikeda-Sobajima-Wakasa for the weakly coupled
system of semilinear wave equations with the same kind of nonlinearities. In
the critical and not-damped case we provide a different approach from the test
function method applied by Ikeda-Sobajima-Wakasa to prove the blow-up of the
solution on the critical curve, improving in some cases the upper bound
estimate for the lifespan. More precisely, we combine an iteration argument
with the so-called slicing method to show the blow-up dynamic of a weighted
version of the functionals used in the subcritical case.",1901.04038v1
2019-01-15,Continuum damping effects in nuclear collisions associated with twisted boundary conditions,"The time-dependent Skyrme Hartree-Fock calculations have been performed to
study $^{24}$Mg +$^{24}$Mg collisions. The twisted boundary conditions, which
can avoid finite box-size effects of the employed 3D coordinate space, have
been implemented. The prolate deformed $^{24}$Mg has been set to different
orientations to study vibrations and rotations of the compound nucleus
$^{48}$Cr. Our time evolution results show continuum damping effects associated
with the twist-averaged boundary condition play a persistent role after the
fusion stage. In particular, a rotational damping in continuum is presented in
calculations of both twist-averaged and absorbing boundary conditions, in which
damping widths can be clearly extracted. It is unusual that the rotating
compound nucleus in continuum evolves towards spherical but still has a
considerable angular momentum.",1901.04736v2
2019-03-03,Spin wave damping in periodic and quasiperiodic magnonic structures,"We investigated the lifetime of spin wave eigenmodes in periodic and
quasiperiodic sequences of Py and Co wires. Those materials differ
significantly in damping coefficients, therefore, the spatial distribution of
the mode amplitude within the structure is important for the lifetime of
collective spin wave excitations. Modes of the lower frequencies prefer to
concentrate in Py wires, because of the lower FMR frequency for this material.
This inhomogeneous distribution of amplitude of modes (with lower amplitude in
material of higher damping and with higher amplitude in material of lower
damping) is preferable for extending the lifetime of the collective excitations
beyond the volume average of lifetimes for solid materials. We established the
relation between the profile of the mode and its lifetime for periodic and
quasiperiodic structures. We performed also the comparative studies in order to
find the differences resulting from complexity of the structure and enhancement
of localization in quasiperiodic system on the lifetime of spin waves.",1903.00856v1
2019-03-07,Investigating optically-excited THz standing spin waves using noncollinear magnetic bilayers,"We investigate optically excited THz standing spin waves in noncollinear
magnetic bilayers. Using femtosecond laser-pulse excitation, a spin current is
generated in the first ferromagnetic (FM) layer, and flows through a conductive
spacer layer to be injected into the second (transverse) FM layer, where it
exerts a spin-transfer torque on the magnetization and excites higher-order
standing spin waves. We show that the noncollinear magnetic bilayer is a
convenient tool that allows easy excitation of THz spin waves, and can be used
to investigate the dispersion and thereby the spin wave stiffness parameter in
the thin-film regime. This is experimentally demonstrated using wedge-shaped Co
and CoB (absorption) layers. Furthermore, the damping of these THz spin waves
is investigated, showing a strong increase of the damping with decreasing
absorption layer thickness, much stronger than expected from interface spin
pumping effects. Additionally, a previously unseen sudden decrease in the
damping for the thinnest films is observed. A model for the additional damping
contribution incorporating both these observations is proposed.",1903.02802v1
2019-03-14,An analog simulation experiment to study free oscillations of a damped simple pendulum,"The characteristics of drive-free oscillations of a damped simple pendulum
under sinusoidal potential force field differ from those of the damped harmonic
oscillations. The frequency of oscillation of a large amplitude simple pendulum
decreases with increasing amplitude. Many prototype mechanical simple pendulum
have been fabricated with precision and studied earlier in view of introducing
them in undergraduate physics laboratories. However, fabrication and
maintenance of such mechanical pendulum require special skill. In this work, we
set up an analog electronic simulation experiment to serve the purpose of
studying the force-free oscillations of a damped simple pendulum. We present
the details of the setup and some typical results of our experiment. The
experiment is simple enough to implement in undergraduate physics laboratories.",1903.06162v1
2019-03-15,Frictional Damping in Biomimetic Scale Beam Oscillations,"Stiff scales adorn the exterior surfaces of fishes, snakes, and many
reptiles. They provide protection from external piercing attacks and control
over global deformation behavior to aid locomotion, slithering, and swimming
across a wide range of environmental condition. In this letter, we investigate
the dynamic behavior of biomimetic scale substrates for further understanding
the origins of the nonlinearity that involve various aspect of scales
interaction, sliding kinematics, interfacial friction, and their combination.
Particularly, we study the vibrational characteristics through an analytical
model and numerical investigations for the case of a simply supported scale
covered beam. Our results reveal for the first time that biomimetic scale beams
exhibit viscous damping behavior even when only Coulomb friction is postulated
for free vibrations. We anticipate and quantify the anisotropy in the damping
behavior with respect to curvature. We also find that unlike static pure
bending where friction increases bending stiffness, a corresponding increase in
natural frequency for the dynamic case does not arise for simply supported
beam. Since both scale geometry, distribution and interfacial properties can be
easily tailored, our study indicates a biomimetic strategy to design
exceptional synthetic materials with tailorable damping behavior.",1903.06819v1
2019-04-08,Damping control in viscoelastic beam dynamics,"Viscoelasticity plays a key role in many practical applications and in
different reasearch fields, such as in seals, sliding-rolling contacts and
crack propagation. In all these contexts, a proper knowledge of the
viscoelastic modulus is very important. However, the experimental
characterization of the frequency dependent modulus, carried out through
different standard procedures, still presents some complexities, then possible
alternative approaches are desirable. For example, the experimental
investigation of viscoelastic beam dynamics would be challenging, especially
for the intrinsic simplicity of this kind of test. This is why, a deep
understanding of damping mechanisms in viscoelastic beams results to be a quite
important task to better predict their dynamics. With the aim to enlighten
damping properties in such structures, an analytical study of the transversal
vibrations of a viscoelastic beam is presented in this paper. Some
dimensionless parameters are defined, depending on the material properties and
the beam geometry, which enable to shrewdly design the beam dynamics. In this
way, by properly tuning such disclosed parameters, for example the
dimensionless beam length or a chosen material, it is possible to enhance or
suppress some resonant peaks, one at a time or more simultaneously. This is a
remarkable possibility to efficiently control damping in these structures, and
the results presented in this paper may help in elucidating experimental
procedures for the characterization of viscoelastic materials.",1904.03875v1
2019-04-28,On the Kolmogorov dissipation law in a damped Navier-Stokes equation,"We consider here the Navier-Stokes equations in $\mathbb{R}^{3}$ with a
stationary, divergence-free external force and with an additional damping term
that depends on two parameters. We first study the well-posedness of weak
solutions for these equations and then, for a particular set of the damping
parameters, we will obtain an upper and lower control for the energy
dissipation rate $\varepsilon$ according to the Kolmogorov K41 theory. However,
although the behavior of weak solutions corresponds to the K41 theory, we will
show that in some specific cases the damping term introduced in the
Navier-Stokes equations could annihilate the turbulence even though the Grashof
number (which are equivalent to the Reynolds number) are large.",1904.12382v1
2019-04-23,Entanglement sudden death and birth effects in two qubits maximally entangled mixed states under quantum channels,"In the present article, the robustness of entanglement in two qubits
maximally entangled mixed states (MEME) have been studied under quantum
decoherence channels. Here we consider bit flip, phase flip, bit-phase-flip,
amplitude damping, phase damping and depolarization channels. To quantify the
entanglement, the concurrence has been used as an entanglement measure. During
this study interesting results have been found for sudden death and birth of
entanglement under bit flip and bit-phase-flip channels. While amplitude
damping channel produces entanglement sudden death and does not allow re-birth
of entanglement. On the other hand, two qubits MEMS exhibit the robust
character against the phase flip, phase damping and depolarization channels.
The elegant behavior of all the quantum channels have been investigated with
varying parameter of quantum state MEMS in different cases.",1904.12630v2
2019-08-13,Dynamics of Riemann waves with sharp measure-controlled damping,"This paper is concerned with locally damped semilinear wave equations defined
on compact Riemannian manifolds with boundary. We present a construction of
measure-controlled damping regions which are sharp in the sense that their
summed interior and boundary measures are arbitrarily small. The construction
of this class of open sets is purely geometric and allows us to prove a new
observability inequality in terms of potential energy rather than the usual one
with kinetic energy. A unique continuation property is also proved. Then, in
three-dimension spaces, we establish the existence of finite dimensional smooth
global attractors for a class of wave equations with nonlinear damping and
forces with critical Sobolev growth. In addition, by means of an obstacle
control condition, we show that our class of measure-controlled regions
satisfies the well-known geometric control condition (GCC). Therefore, many of
known results for the stabilization of wave equations hold true in the present
context.",1908.04814v1
2019-08-15,Sharp polynomial decay rates for the damped wave equation with Hölder-like damping,"We study decay rates for the energy of solutions of the damped wave equation
on the torus. We consider dampings invariant in one direction and bounded above
and below by multiples of $x^{\beta}$ near the boundary of the support and show
decay at rate $1/t^{\frac{\beta+2}{\beta+3}}$. In the case where $W$ vanishes
exactly like $x^{\beta}$ this result is optimal by work of the second author.
The proof uses a version of the Morawetz multiplier method.",1908.05631v3
2019-08-26,Revisiting the Coulomb-Damped Harmonic Oscillator,"The force of dry friction is studied extensively in introductory physics but
its effect on oscillations is hardly ever mentioned. Instead, to provide a
mathematically tractable introduction to damping, virtually all authors adopt a
viscous resistive force. While exposure to linear damping is of paramount
importance to the student of physics, the omission of Coulomb damping might
have a negative impact on the way the students conceive of the subject. In the
paper, we propose to approximate the action of Coulomb friction on a harmonic
oscillator by a sinusoidal resistive force whose amplitude is the model's only
free parameter. We seek the value of this parameter that yields the best fit
and obtain a closed-form analytic solution, which is shown to nicely fit the
numerical one.",1908.10363v1
2019-11-05,Exceptional points in dissipatively coupled spin dynamics,"We theoretically investigate dynamics of classical spins exchange-coupled
through an isotropic medium. The coupling is treated at the adiabatic level of
the medium's response, which mediates a first-order in frequency dissipative
interaction along with an instantaneous Heisenberg exchange. The resultant
damped spin precession yields exceptional points (EPs) in the coupled spin
dynamics, which should be experimentally accessible with the existing magnetic
heterostructures. In particular, we show that an EP is naturally approached in
an antiferromagnetic dimer by controlling local damping, while the same is
achieved by tuning the dissipative coupling between spins in the ferromagnetic
case. Extending our treatment to one-dimensional spin chains, we show how EPs
can emerge within the magnonic Brillouin zone by tuning the dissipative
properties. The critical point, at which an EP pair emerges out of the
Brillouin zone center, realizes a gapless Weyl point in the magnon spectrum.
Tuning damping beyond this critical point produces synchronization (level
attraction) of magnon modes over a finite range of momenta, both in ferro- and
antiferromagnetic cases. We thus establish that damped magnons can generically
yield singular points in their band structure, close to which their kinematic
properties, such as group velocity, become extremely sensitive to the control
parameters.",1911.01619v2
2019-11-07,Quantum Oscillations of Gilbert Damping in Ferromagnetic/Graphene Bilayer Systems,"We study the spin dynamics of a ferromagnetic insulator on which graphene is
placed. We show that the Gilbert damping is enhanced by the proximity exchange
coupling at the interface. The modulation of the Gilbert damping constant is
proportional to the product of the spin-up and spin-down densities of states of
graphene. Consequently, the Gilbert damping constant in a strong magnetic field
oscillates as a function of the external magnetic field that originates from
the Landau level structure of graphene. We find that a measurement of the
oscillation period enables the strength of the exchange coupling constant to be
determined. The results demonstrate in theory that the ferromagnetic resonance
measurements may be used to detect the spin resolved electronic structure of
the adjacent materials, which is critically important for future spin device
evaluations.",1911.02775v2
2019-11-08,Influence of Sensor Feedback Limitations on Power Oscillation Damping and Transient Stability,"Fundamental sensor feedback limitations for improving rotor angle stability
using local frequency or phase angle measurement are derived. Using a
two-machine power system model, it is shown that improved damping of inter-area
oscillations must come at the cost of reduced transient stability margins,
regardless of the control design method. The control limitations stem from that
the excitation of an inter-area mode by external disturbances cannot be
estimated with certainty using local frequency information. The results are
validated on a modified Kundur four-machine two-area test system where the
active power is modulated on an embedded high-voltage dc link. Damping control
using local phase angle measurements, unavoidably leads to an increased rotor
angle deviation following certain load disturbances. For a highly stressed
system, it is shown that this may lead to transient instability. The
limitations derived in the paper may motivate the need for wide-area
measurements in power oscillation damping control.",1911.03342v3
2019-11-12,Non-uniform Stability of Damped Contraction Semigroups,"We investigate the stability properties of strongly continuous semigroups
generated by operators of the form $A-BB^\ast$, where $A$ is a generator of a
contraction semigroup and $B$ is a possibly unbounded operator. Such systems
arise naturally in the study of hyperbolic partial differential equations with
damping on the boundary or inside the spatial domain. As our main results we
present general sufficient conditions for non-uniform stability of the
semigroup generated by $A-BB^\ast$ in terms of selected observability-type
conditions of the pair $(B^\ast,A)$. We apply the abstract results to obtain
rates of energy decay in one-dimensional and two-dimensional wave equations, a
damped fractional Klein--Gordon equation and a weakly damped beam equation.",1911.04804v3
2020-03-05,Sound propagation and quantum limited damping in a two-dimensional Fermi gas,"Strongly interacting two-dimensional Fermi systems are one of the great
remaining challenges in many-body physics due to the interplay of strong local
correlations and enhanced long-range fluctuations. Here, we probe the
thermodynamic and transport properties of a 2D Fermi gas across the BEC-BCS
crossover by studying the propagation and damping of sound modes. We excite
particle currents by imprinting a phase step onto homogeneous Fermi gases
trapped in a box potential and extract the speed of sound from the frequency of
the resulting density oscillations. We measure the speed of sound across the
BEC-BCS crossover and compare the resulting dynamic measurement of the equation
of state both to a static measurement based on recording density profiles and
to Quantum Monte Carlo calculations and find reasonable agreement between all
three. We also measure the damping of the sound mode, which is determined by
the shear and bulk viscosities as well as the thermal conductivity of the gas.
We find that the damping is minimal in the strongly interacting regime and the
diffusivity approaches the universal quantum bound $\hbar/m$ of a perfect
fluid.",2003.02713v1
2020-03-09,Proof-of-principle direct measurement of Landau damping strength at the Large Hadron Collider with an anti-damper,"Landau damping is an essential mechanism for ensuring collective beam
stability in particle accelerators. Precise knowledge of how strong Landau
damping is, is key to making accurate predictions on beam stability for
state-of-the-art high energy colliders. In this paper we demonstrate an
experimental procedure that would allow quantifying the strength of Landau
damping and the limits of beam stability using an active transverse feedback as
a controllable source of beam coupling impedance. In a proof-of-principle test
performed at the Large Hadron Collider stability diagrams for a range of Landau
Octupole strengths have been measured. In the future, the procedure could
become an accurate way of measuring stability diagrams throughout the machine
cycle.",2003.04383v1
2020-03-19,An inverse-system method for identification of damping rate functions in non-Markovian quantum systems,"Identification of complicated quantum environments lies in the core of
quantum engineering, which systematically constructs an environment model with
the aim of accurate control of quantum systems. In this paper, we present an
inverse-system method to identify damping rate functions which describe
non-Markovian environments in time-convolution-less master equations. To access
information on the environment, we couple a finite-level quantum system to the
environment and measure time traces of local observables of the system. By
using sufficient measurement results, an algorithm is designed, which can
simultaneously estimate multiple damping rate functions for different
dissipative channels. Further, we show that identifiability for the damping
rate functions corresponds to the invertibility of the system and a necessary
condition for identifiability is also given. The effectiveness of our method is
shown in examples of an atom and three-spin-chain non-Markovian systems.",2003.08617v1
2020-05-04,Plasmon damping in electronically open systems,"Rapid progress in electrically-controlled plasmonics in solids poses a
question about effects of electronic reservoirs on the properties of plasmons.
We find that plasmons in electronically open systems [i.e. in (semi)conductors
connected to leads] are prone to an additional damping due to charge carrier
penetration into contacts and subsequent thermalization. We develop a theory of
such lead-induced damping based on kinetic equation with self-consistent
electric field, supplemented by microscopic carrier transport at the
interfaces. The lifetime of plasmon in electronically open ballistic system
appears to be finite, order of conductor length divided by carrier Fermi
(thermal) velocity. The reflection loss of plasmon incident on the contact of
semi-conductor and perfectly conducting metal also appears to be finite, order
of Fermi velocity divided by wave phase velocity. Recent experiments on
plasmon-assisted photodetection are discussed in light of the proposed
lead-induced damping phenomenon.",2005.01680v1
2020-05-06,Helical damping and anomalous critical non-Hermitian skin effect,"Non-Hermitian skin effect and critical skin effect are unique features of
non-Hermitian systems. In this Letter, we study an open system with its
dynamics of single-particle correlation function effectively dominated by a
non-Hermitian damping matrix, which exhibits $\mathbb{Z}_2$ skin effect, and
uncover the existence of a novel phenomenon of helical damping. When adding
perturbations that break anomalous time reversal symmetry to the system, the
critical skin effect occurs, which causes the disappearance of the helical
damping in the thermodynamic limit although it can exist in small size systems.
We also demonstrate the existence of anomalous critical skin effect when we
couple two identical systems with $\mathbb{Z}_2$ skin effect. With the help of
non-Bloch band theory, we unveil that the change of generalized Brillouin zone
equation is the necessary condition of critical skin effect.",2005.02617v1
2020-05-16,Gravitational Landau Damping for massive scalar modes,"We establish the possibility of Landau damping for gravitational scalar waves
which propagate in a non-collisional gas of particles. In particular, under the
hypothesis of homogeneity and isotropy, we describe the medium at the
equilibrium with a J\""uttner-Maxwell distribution, and we analytically
determine the damping rate from the Vlasov equation. We find that damping
occurs only if the phase velocity of the wave is subluminal throughout the
propagation within the medium. Finally, we investigate relativistic media in
cosmological settings by adopting numerical techniques.",2005.08010v4
2020-05-21,"On Strong Feller Property, Exponential Ergodicity and Large Deviations Principle for Stochastic Damping Hamiltonian Systems with State-Dependent Switching","This work focuses on a class of stochastic damping Hamiltonian systems with
state-dependent switching, where the switching process has a countably infinite
state space. After establishing the existence and uniqueness of a global weak
solution via the martingale approach under very mild conditions, the paper next
proves the strong Feller property for regime-switching stochastic damping
Hamiltonian systems by the killing technique together with some resolvent and
transition probability identities. The commonly used continuity assumption for
the switching rates $q_{kl}(\cdot)$ in the literature is relaxed to
measurability in this paper. Finally the paper provides sufficient conditions
for exponential ergodicity and large deviations principle for regime-switching
stochastic damping Hamiltonian systems. Several examples on regime-switching
van der Pol and (overdamped) Langevin systems are studied in detail for
illustration.",2005.10730v1
2020-06-09,Logarithmic decay for damped hypoelliptic wave and Schr{ö}dinger equations,"We consider damped wave (resp. Schr{\""o}dinger and plate) equations driven by
a hypoelliptic ""sum of squares"" operator L on a compact manifold and a damping
function b(x). We assume the Chow-Rashevski-H{\""o}rmander condition at rank k
(at most k Lie brackets needed to span the tangent space) together with
analyticity of M and the coefficients of L. We prove decay of the energy at
rate $log(t)^{-1/k}$ (resp. $log(t)^{-2/k}$ ) for data in the domain of the
generator of the associated group. We show that this decay is optimal on a
family of Grushin-type operators. This result follows from a perturbative
argument (of independent interest) showing, in a general abstract setting, that
quantitative approximate observability/controllability results for wave-type
equations imply a priori decay rates for associated damped wave,
Schr{\""o}dinger and plate equations. The adapted quantitative approximate
observability/controllability theorem for hypoelliptic waves is obtained by the
authors in [LL19, LL17].",2006.05122v1
2020-06-14,Bulk Viscous Damping of Density Oscillations in Neutron Star Mergers,"In this paper, we discuss the damping of density oscillations in dense
nuclear matter in the temperature range relevant to neutron star mergers. This
damping is due to bulk viscosity arising from the weak interaction ``Urca''
processes of neutron decay and electron capture. The nuclear matter is modelled
in the relativistic density functional approach. The bulk viscosity reaches a
resonant maximum close to the neutrino trapping temperature, then drops rapidly
as temperature rises into the range where neutrinos are trapped in neutron
stars. We investigate the bulk viscous dissipation timescales in a post-merger
object and identify regimes where these timescales are as short as the
characteristic timescale $\sim$10 ms, and, therefore, might affect the
evolution of the post-merger object. Our analysis indicates that bulk viscous
damping would be important at not too high temperatures of the order of a few
MeV and densities up to a few times saturation density.",2006.07975v2
2020-06-15,Exact solutions of a damped harmonic oscillator in a time dependent noncommutative space,"In this paper we have obtained the exact eigenstates of a two dimensional
damped harmonic oscillator in time dependent noncommutative space. It has been
observed that for some specific choices of the damping factor and the time
dependent frequency of the oscillator, there exists interesting solutions of
the time dependent noncommutative parameters following from the solutions of
the Ermakov-Pinney equation. Further, these solutions enable us to get exact
analytic forms for the phase which relates the eigenstates of the Hamiltonian
with the eigenstates of the Lewis invariant. We then obtain expressions for the
matrix elements of the coordinate operators raised to a finite arbitrary power.
From these general results we then compute the expectation value of the
Hamiltonian. The expectation values of the energy are found to vary with time
for different solutions of the Ermakov-Pinney equation corresponding to
different choices of the damping factor and the time dependent frequency of the
oscillator.",2006.08611v1
2020-06-16,Enhancing nonlinear damping by parametric-direct internal resonance,"Mechanical sources of nonlinear damping play a central role in modern
physics, from solid-state physics to thermodynamics. The microscopic theory of
mechanical dissipation [M. I . Dykman, M. A. Krivoglaz, Physica Status Solidi
(b) 68, 111 (1975)] suggests that nonlinear damping of a resonant mode can be
strongly enhanced when it is coupled to a vibration mode that is close to twice
its resonance frequency. To date, no experimental evidence of this enhancement
has been realized. In this letter, we experimentally show that nanoresonators
driven into parametric-direct internal resonance provide supporting evidence
for the microscopic theory of nonlinear dissipation. By regulating the drive
level, we tune the parametric resonance of a graphene nanodrum over a range of
40-70 MHz to reach successive two-to-one internal resonances, leading to a
nearly two-fold increase of the nonlinear damping. Our study opens up an
exciting route towards utilizing modal interactions and parametric resonance to
realize resonators with engineered nonlinear dissipation over wide frequency
range.",2006.09364v3
2020-06-22,Blow-up for wave equation with the scale-invariant damping and combined nonlinearities,"In this article, we study the blow-up of the damped wave equation in the
\textit{scale-invariant case} and in the presence of two nonlinearities. More
precisely, we consider the following equation: $$u_{tt}-\Delta
u+\frac{\mu}{1+t}u_t=|u_t|^p+|u|^q, \quad \mbox{in}\ \R^N\times[0,\infty), $$
with small initial data.\\ For $\mu < \frac{N(q-1)}{2}$ and $\mu \in (0,
\mu_*)$, where $\mu_*>0$ is depending on the nonlinearties' powers and the
space dimension ($\mu_*$ satisfies $(q-1)\left((N+2\mu_*-1)p-2\right) = 4$), we
prove that the wave equation, in this case, behaves like the one without
dissipation ($\mu =0$). Our result completes the previous studies in the case
where the dissipation is given by $\frac{\mu}{(1+t)^\beta}u_t; \ \beta >1$
(\cite{LT3}), where, contrary to what we obtain in the present work, the effect
of the damping is not significant in the dynamics. Interestingly, in our case,
the influence of the damping term $\frac{\mu}{1+t}u_t$ is important.",2006.12600v1
2020-06-30,Negative Gilbert damping in cavity optomagnonics,"Exceptional point (EP) associated with the parity-time (PT) symmetry breaking
is receiving considerable recent attention by the broad physics community. By
introducing balanced gain and loss, it has been realized in photonic, acoustic,
and electronic structures. However, the observation of magnonic EP remains
elusive. The major challenge is to experimentally generate the negative Gilbert
damping, which was thought to be highly unlikely but is demanded by the PT
symmetry. In this work, we study the magneto-optical interaction of
circularly-polarized lasers with a submicron magnet placed in an optical
cavity. We show that the off-resonant coupling between the driving laser and
cavity photon in the far-blue detuning can induce the magnetic gain (or
negative damping) exactly of the Gilbert type. A hyperbolic-tangent function
ansatz is found to well describe the time-resolved spin switching as the
intrinsic magnetization dissipation is overcome. When the optically pumped
magnet interacts with a purely lossy one, we observe a phase transition from
the imbalanced to passive PT symmetries by varying the detuning coeffcient. Our
findings provide a feasible way to manipulate the sign of the magnetic damping
parameter and to realize the EP in cavity optomagnonics.",2006.16510v1
2020-08-06,Quantum sensing of open systems: Estimation of damping constants and temperature,"We determine quantum precision limits for estimation of damping constants and
temperature of lossy bosonic channels. A direct application would be the use of
light for estimation of the absorption and the temperature of a transparent
slab. Analytic lower bounds are obtained for the uncertainty in the estimation,
through a purification procedure that replaces the master equation description
by a unitary evolution involving the system and ad hoc environments. For zero
temperature, Fock states are shown to lead to the minimal uncertainty in the
estimation of damping, with boson-counting being the best measurement
procedure. In both damping and temperature estimates, sequential
pre-thermalization measurements, through a stream of single bosons, may lead to
huge gain in precision.",2008.02728v1
2020-08-07,Quantifying the evidence for resonant damping of coronal waves with foot-point wave power asymmetry,"We use Coronal Multi-channel Polarimeter (CoMP) observations of propagating
waves in the solar corona and Bayesian analysis to assess the evidence of
models with resonant damping and foot-point wave power asymmetries. Two nested
models are considered. The reduced model considers resonant damping as the sole
cause of the measured discrepancy between outward and inward wave power. The
larger model contemplates an extra source of asymmetry with origin at the
foot-points. We first compute probability distributions of parameters
conditional on the models and the observed data. The obtained constraints are
then used to calculate the evidence for each model in view of data. We find
that we need to consider the larger model to explain CoMP data and to
accurately infer the damping ratio, hence, to better assess the possible
contribution of the waves to coronal heating.",2008.03004v1
2020-08-22,Sound damping in frictionless granular materials: The interplay between configurational disorder and inelasticity,"We numerically investigate sound damping in a model of granular materials in
two dimensions. We simulate evolution of standing waves in disordered
frictionless disks and analyze their damped oscillations by velocity
autocorrelation functions and power spectra. We control the strength of
inelastic interactions between the disks in contact to examine the effect of
energy dissipation on sound characteristics of disordered systems. Increasing
the strength of inelastic interactions, we find that (i) sound softening
vanishes and (ii) sound attenuation due to configurational disorder, i.e. the
Rayleigh scattering at low frequencies and disorder-induced broadening at high
frequencies, is completely dominated by the energy dissipation. Our findings
suggest that sound damping in granular media is determined by the interplay
between elastic heterogeneities and inelastic interactions.",2008.09760v1
2020-09-27,Squeezed comb states,"Continuous-variable codes are an expedient solution for quantum information
processing and quantum communication involving optical networks. Here we
characterize the squeezed comb, a finite superposition of equidistant squeezed
coherent states on a line, and its properties as a continuous-variable encoding
choice for a logical qubit. The squeezed comb is a realistic approximation to
the ideal code proposed by Gottesman, Kitaev, and Preskill [Phys. Rev. A 64,
012310 (2001)], which is fully protected against errors caused by the
paradigmatic types of quantum noise in continuous-variable systems: damping and
diffusion. This is no longer the case for the code space of finite squeezed
combs, and noise robustness depends crucially on the encoding parameters. We
analyze finite squeezed comb states in phase space, highlighting their
complicated interference features and characterizing their dynamics when
exposed to amplitude damping and Gaussian diffusion noise processes. We find
that squeezed comb state are more suitable and less error-prone when exposed to
damping, which speaks against standard error correction strategies that employ
linear amplification to convert damping into easier-to-describe isotropic
diffusion noise.",2009.12888v2
2020-11-16,Switchable Damping for a One-Particle Oscillator,"The possibility to switch the damping rate for a one-electron oscillator is
demonstrated, for an electron that oscillates along the magnetic field axis in
a Penning trap. Strong axial damping can be switched on to allow this
oscillation to be used for quantum nondemolition detection of the cyclotron and
spin quantum state of the electron. Weak axial damping can be switched on to
circumvent the backaction of the detection motion that has limited past
measurements. The newly developed switch will reduce the linewidth of the
cyclotron transition of one-electron by two orders of magnitude.",2011.08136v2
2020-11-15,A Random Matrix Theory Approach to Damping in Deep Learning,"We conjecture that the inherent difference in generalisation between adaptive
and non-adaptive gradient methods in deep learning stems from the increased
estimation noise in the flattest directions of the true loss surface. We
demonstrate that typical schedules used for adaptive methods (with low
numerical stability or damping constants) serve to bias relative movement
towards flat directions relative to sharp directions, effectively amplifying
the noise-to-signal ratio and harming generalisation. We further demonstrate
that the numerical damping constant used in these methods can be decomposed
into a learning rate reduction and linear shrinkage of the estimated curvature
matrix. We then demonstrate significant generalisation improvements by
increasing the shrinkage coefficient, closing the generalisation gap entirely
in both logistic regression and several deep neural network experiments.
Extending this line further, we develop a novel random matrix theory based
damping learner for second order optimiser inspired by linear shrinkage
estimation. We experimentally demonstrate our learner to be very insensitive to
the initialised value and to allow for extremely fast convergence in
conjunction with continued stable training and competitive generalisation.",2011.08181v5
2020-11-17,Challenging an experimental nonlinear modal analysis method with a new strongly friction-damped structure,"In this work, we show that a recently proposed method for experimental
nonlinear modal analysis based on the extended periodic motion concept is well
suited to extract modal properties for strongly nonlinear systems (i.e. in the
presence of large frequency shifts, high and nonlinear damping, changes of the
mode shape, and higher harmonics). To this end, we design a new test rig that
exhibits a large extent of friction-induced damping (modal damping ratio up to
15 %) and frequency shift by 36 %. The specimen, called RubBeR, is a
cantilevered beam under the influence of dry friction, ranging from full stick
to mainly sliding. With the specimen's design, the measurements are well
repeatable for a system subjected to dry frictional force. Then, we apply the
method to the specimen and show that single-point excitation is sufficient to
track the modal properties even though the deflection shape changes with
amplitude. Computed frequency responses using a single nonlinear-modal
oscillator with the identified modal properties agree well with measured
reference curves of different excitation levels, indicating the modal
properties' significance and accuracy.",2011.08527v1
2020-11-27,Thermal damping of Weak Magnetosonic Turbulence in the Interstellar Medium,"We present a generic mechanism for the thermal damping of compressive waves
in the interstellar medium (ISM), occurring due to radiative cooling. We solve
for the dispersion relation of magnetosonic waves in a two-fluid (ion-neutral)
system in which density- and temperature-dependent heating and cooling
mechanisms are present. We use this dispersion relation, in addition to an
analytic approximation for the nonlinear turbulent cascade, to model
dissipation of weak magnetosonic turbulence. We show that in some ISM
conditions, the cutoff wavelength for magnetosonic turbulence becomes tens to
hundreds of times larger when the thermal damping is added to the regular
ion-neutral damping. We also run numerical simulations which confirm that this
effect has a dramatic impact on cascade of compressive wave modes.",2011.13879v3
2021-02-10,WAMS-Based Model-Free Wide-Area Damping Control by Voltage Source Converters,"In this paper, a novel model-free wide-area damping control (WADC) method is
proposed, which can achieve full decoupling of modes and damp multiple critical
inter-area oscillations simultaneously using grid-connected voltage source
converters (VSCs). The proposed method is purely measurement based and requires
no knowledge of the network topology and the dynamic model parameters. Hence,
the designed controller using VSCs can update the control signals online as the
system operating condition varies. Numerical studies in the modified IEEE
68-bus system with grid-connected VSCs show that the proposed method can
estimate the system dynamic model accurately and can damp inter-area
oscillations effectively under different working conditions and network
topologies.",2102.05494v1
2021-03-11,Magnetoelastic Gilbert damping in magnetostrictive Fe$_{0.7}$Ga$_{0.3}$ thin films,"We report an enhanced magnetoelastic contribution to the Gilbert damping in
highly magnetostrictive Fe$_{0.7}$Ga$_{0.3}$ thin films. This effect is
mitigated for perpendicular-to-plane fields, leading to a large anisotropy of
the Gilbert damping in all of the films (up to a factor of 10 at room
temperature). These claims are supported by broadband measurements of the
ferromagnetic resonance linewidths over a range of temperatures (5 to 400 K),
which serve to elucidate the effect of both the magnetostriction and phonon
relaxation on the magnetoelastic Gilbert damping.",2103.07008v1
2021-04-08,Fast optimization of viscosities for frequency-weighted damping of second-order systems,"We consider frequency-weighted damping optimization for vibrating systems
described by a second-order differential equation. The goal is to determine
viscosity values such that eigenvalues are kept away from certain undesirable
areas on the imaginary axis. To this end, we present two complementary
techniques. First, we propose new frameworks using nonsmooth constrained
optimization problems, whose solutions both damp undesirable frequency bands
and maintain stability of the system. These frameworks also allow us to weight
which frequency bands are the most important to damp. Second, we also propose a
fast new eigensolver for the structured quadratic eigenvalue problems that
appear in such vibrating systems. In order to be efficient, our new eigensolver
exploits special properties of diagonal-plus-rank-one complex symmetric
matrices, which we leverage by showing how each quadratic eigenvalue problem
can be transformed into a short sequence of such linear eigenvalue problems.
The result is an eigensolver that is substantially faster than standard
techniques. By combining this new solver with our new optimization frameworks,
we obtain our overall algorithm for fast computation of optimal viscosities.
The efficiency and performance of our new methods are verified and illustrated
on several numerical examples.",2104.04035v1
2021-04-09,"Nonexistence result for the generalized Tricomi equation with the scale-invariant damping, mass term and time derivative nonlinearity","In this article, we consider the damped wave equation in the
\textit{scale-invariant case} with time-dependent speed of propagation, mass
term and time derivative nonlinearity. More precisely, we study the blow-up of
the solutions to the following equation: $$ (E) \quad u_{tt}-t^{2m}\Delta
u+\frac{\mu}{t}u_t+\frac{\nu^2}{t^2}u=|u_t|^p, \quad \mbox{in}\
\mathbb{R}^N\times[1,\infty), $$ that we associate with small initial data.
Assuming some assumptions on the mass and damping coefficients, $\nu$ and
$\mu>0$, respectively, that the blow-up region and the lifespan bound of the
solution of $(E)$ remain the same as the ones obtained for the case without
mass, {\it i.e.} $\nu=0$ in $(E)$. The latter case constitutes, in fact, a
shift of the dimension $N$ by $\frac{\mu}{1+m}$ compared to the problem without
damping and mass. Finally, we think that the new bound for $p$ is a serious
candidate to the critical exponent which characterizes the threshold between
the blow-up and the global existence regions.",2104.04393v2
2021-04-12,Slow periodic oscillation without radiation damping: New evolution laws for rate and state friction,"The dynamics of sliding friction is mainly governed by the frictional force.
Previous studies have shown that the laboratory-scale friction is well
described by an empirical law stated in terms of the slip velocity and the
state variable. The state variable represents the detailed physicochemical
state of the sliding interface. Despite some theoretical attempts to derive
this friction law, there has been no unique equation for time evolution of the
state variable. Major equations known to date have their own merits and
drawbacks. To shed light on this problem from a new aspect, here we investigate
the feasibility of periodic motion without the help of radiation damping.
Assuming a patch on which the slip velocity is perturbed from the rest of the
sliding interface, we prove analytically that three major evolution laws fail
to reproduce stable periodic motion without radiation damping. Furthermore, we
propose two new evolution equations that can produce stable periodic motion
without radiation damping. These two equations are scrutinized from the
viewpoint of experimental validity and the relevance to slow earthquakes.",2104.05398v2
2021-04-27,Absence of a boson peak in anharmonic phonon models with Akhiezer-type damping,"In a recent article M. Baggioli and A. Zaccone (Phys. Rev. Lett. {\bf 112},
145501 (2019)) claimed that an anharmonic damping, leading to a sound
attenuation proportional to $\omega^2$ (Akhiezer-type damping) would imply a
boson peak, i.e.\ a maximum in the vibrational density of states, divided by
the frequency squared (reduced density of states). This would apply both to
glasses and crystals.Here we show that this is not the case. In a
mathematically correct treatment of the model the reduced density of states
monotonously decreases, i.e.\ there is no boson peak. We further show that the
formula for the would-be boson peak, presented by the authors, corresponds to a
very short one-dimensional damped oscillator system. The peaks they show
correspond to resonances, which vanish in the thermodynamic limit.",2104.13076v1
2021-05-03,Damping and polarization rates in near equilibrium state,"The collision terms in spin transport theory are analyzed in Kadanoff-Baym
formalism for systems close to equilibrium. The non-equilibrium fluctuations in
spin distribution include both damping and polarization, with the latter
arising from the exchange between orbital and spin angular momenta. The damping
and polarization rates or the relaxation times are expressed in terms of
various Dirac components of the self-energy. Unlike the usually used
Anderson-Witting relaxation time approximation assuming a single time scale for
different degrees of freedom, the polarization effect is induced by the thermal
vorticity and its time scale of thermalization is different from the damping.
The numerical calculation in the Nambu--Jona-Lasinio model shows that, charge
is thermalized earlier and spin is thermalized later.",2105.00915v1
2021-06-07,Voltage-control of damping constant in magnetic-insulator/topological-insulator bilayers,"The magnetic damping constant is a critical parameter for magnetization
dynamics and the efficiency of memory devices and magnon transport. Therefore,
its manipulation by electric fields is crucial in spintronics. Here, we
theoretically demonstrate the voltage-control of magnetic damping in ferro- and
ferrimagnetic-insulator (FI)/topological-insulator (TI) bilayers. Assuming a
capacitor-like setup, we formulate an effective dissipation torque induced by
spin-charge pumping at the FI/TI interface as a function of an applied voltage.
By using realistic material parameters, we find that the effective damping for
a FI with 10nm thickness can be tuned by one order of magnitude under the
voltage with 0.25V. Also, we provide perspectives on the voltage-induced
modulation of the magnon spin transport on proximity-coupled FIs.",2106.03332v1
2021-05-14,Exact solution of damped harmonic oscillator with a magnetic field in a time dependent noncommutative space,"In this paper we have obtained the exact eigenstates of a two dimensional
damped harmonic oscillator in the presence of an external magnetic field
varying with respect to time in time dependent noncommutative space. It has
been observed that for some specific choices of the damping factor, the time
dependent frequency of the oscillator and the time dependent external magnetic
field, there exists interesting solutions of the time dependent noncommutative
parameters following from the solutions of the Ermakov-Pinney equation.
Further, these solutions enable us to get exact analytic forms for the phase
which relates the eigenstates of the Hamiltonian with the eigenstates of the
Lewis invariant. Then we compute the expectation value of the Hamiltonian. The
expectation values of the energy are found to vary with time for different
solutions of the Ermakov-Pinney equation corresponding to different choices of
the damping factor, the time dependent frequency of the oscillator and the time
dependent applied magnetic field. We also compare our results with those in the
absence of the magnetic field obtained earlier.",2106.05182v1
2021-06-21,Self-stabilization of light sails by damped internal degrees of freedom,"We consider the motion of a light sail that is accelerated by a powerful
laser beam. We derive the equations of motion for two proof-of-concept sail
designs with damped internal degrees of freedom. Using linear stability
analysis we show that perturbations of the sail movement in all lateral degrees
of freedom can be damped passively. This analysis also shows complicated
behaviour akin to that associated with exceptional points in PT-symmetric
systems in optics and quantum mechanics. The excess heat that is produced by
the damping mechanism is likely to be substantially smaller than the expected
heating due to the partial absorption of the incident laser beam by the sail.",2106.10961v1
2021-07-14,Determining the source of phase noise: Response of a driven Duffing oscillator to low-frequency damping and resonance frequency fluctuations,"We present an analytical calculation of the response of a driven Duffing
oscillator to low-frequency fluctuations in the resonance frequency and
damping. We find that fluctuations in these parameters manifest themselves
distinctively, allowing them to be distinguished. In the strongly nonlinear
regime, amplitude and phase noise due to resonance frequency fluctuations and
amplitude noise due to damping fluctuations are strongly attenuated, while the
transduction of damping fluctuations into phase noise remains of order $1$. We
show that this can be seen by comparing the relative strengths of the amplitude
fluctuations to the fluctuations in the quadrature components, and suggest that
this provides a means to determine the source of low-frequency noise in a
driven Duffing oscillator.",2107.06879v1
2021-07-27,Spin transport-induced damping of coherent THz spin dynamics in iron,"We study the damping of perpendicular standing spin-waves (PSSWs) in
ultrathin Fe films at frequencies up to 2.4 THz. The PSSWs are excited by
optically generated ultrashort spin current pulses, and probed optically in the
time domain. Analyzing the wavenumber and thickness dependence of the damping,
we demonstrate that at sufficiently large wave vectors $k$ the damping is
dominated by spin transport effects scaling with k^4 and limiting the frequency
range of observable PSSWs. Although this contribution is known to originate in
the spin diffusion, we argue that at moderate and large k a more general
description is necessary and develop a model where the 'transverse spin mean
free path' is the a key parameter, and estimate it to be ~0.5 nm.",2107.12812v2
2021-07-29,A N-dimensional elastic\viscoelastic transmission problem with Kelvin-Voigt damping and non smooth coefficient at the interface,"We investigate the stabilization of a multidimensional system of coupled wave
equations with only one Kelvin Voigt damping. Using a unique continuation
result based on a Carleman estimate and a general criteria of Arendt Batty, we
prove the strong stability of the system in the absence of the compactness of
the resolvent without any geometric condition. Then, using a spectral analysis,
we prove the non uniform stability of the system. Further, using frequency
domain approach combined with a multiplier technique, we establish some
polynomial stability results by considering different geometric conditions on
the coupling and damping domains. In addition, we establish two polynomial
energy decay rates of the system on a square domain where the damping and the
coupling are localized in a vertical strip.",2107.13785v1
2021-09-03,Stabilization of the damped plate equation under general boundary conditions,"We consider a damped plate equation on an open bounded subset of R^d, or a
smooth manifold, with boundary, along with general boundary operators
fulfilling the Lopatinskii-Sapiro condition. The damping term acts on a region
without imposing a geometrical condition. We derive a resolvent estimate for
the generator of the damped plate semigroup that yields a logarithmic decay of
the energy of the solution to the plate equation. The resolvent estimate is a
consequence of a Carleman inequality obtained for the bi-Laplace operator
involving a spectral parameter under the considered boundary conditions. The
derivation goes first though microlocal estimates, then local estimates, and
finally a global estimate.",2109.01521v2
2021-09-07,Fluid energy cascade rate and kinetic damping: new insight from 3D Landau-fluid simulations,"Using an exact law for incompressible Hall magnetohydrodynamics (HMHD)
turbulence, the energy cascade rate is computed from three-dimensional HMHD-CGL
(bi-adiabatic ions and isothermal electrons) and Landau fluid (LF) numerical
simulations that feature different intensities of Landau damping over a broad
range of wavenumbers, typically $0.05\lesssim k_\perp d_i \lesssim100$. Using
three sets of cross-scale simulations where turbulence is initiated at large,
medium and small scales, the ability of the fluid energy cascade to ""sense"" the
kinetic Landau damping at different scales is tested. The cascade rate
estimated from the exact law and the dissipation calculated directly from the
simulation are shown to reflect the role of Landau damping in dissipating
energy at all scales, with an emphasis on the kinetic ones. This result
provides new prospects on using exact laws for simplified fluid models to
analyze dissipation in kinetic simulations and spacecraft observations, and new
insights into theoretical description of collisionless magnetized plasmas.",2109.03123v2
2021-09-24,Effect of nonlocal transformations on the linearizability and exact solvability of the nonlinear generalized modified Emden type equations,"The nonlinear generalized modified Emden type equations (GMEE) are known to
be linearizable into simple harmonic oscillator (HO) or damped harmonic
oscillators (DHO) via some nonlocal transformations. Hereby, we show that the
structure of the nonlocal transformation and the linearizability into HO or DHO
determine the nature/structure of the dynamical forces involved (hence,
determine the structure of the dynamical equation). Yet, a reverse engineering
strategy is used so that the exact solutions of the emerging GMEE are
nonlocally transformed to find the exact solutions of the HO and DHO dynamical
equations. Consequently, whilst the exact solution for the HO remains a
textbook one, the exact solution for the DHO (never reported elsewhere, to the
best of our knowledge) turns out to be manifestly the most explicit and general
solution that offers consistency and comprehensive coverage for the associated
under-damping, critical-damping, and over-damping cases (i.e., no complex
settings for the coordinates and/or the velocities are eminent/feasible).
Moreover, for all emerging dynamical system, we report illustrative figures for
each solution as well as the corresponding phase-space trajectories as they
evolve in time.",2109.12059v1
2021-12-27,Trajectory attractors for 3D damped Euler equations and their approximation,"We study the global attractors for the damped 3D Euler--Bardina equations
with the regularization parameter $\alpha>0$ and Ekman damping coefficient
$\gamma>0$ endowed with periodic boundary conditions as well as their damped
Euler limit $\alpha\to0$. We prove that despite the possible non-uniqueness of
solutions of the limit Euler system and even the non-existence of such
solutions in the distributional sense, the limit dynamics of the corresponding
dissipative solutions introduced by P.\,Lions can be described in terms of
attractors of the properly constructed trajectory dynamical system. Moreover,
the convergence of the attractors $\Cal A(\alpha)$ of the regularized system to
the limit trajectory attractor $\Cal A(0)$ as $\alpha\to0$ is also established
in terms of the upper semicontinuity in the properly defined functional space.",2112.13691v1
2022-01-12,Implicit Bias of MSE Gradient Optimization in Underparameterized Neural Networks,"We study the dynamics of a neural network in function space when optimizing
the mean squared error via gradient flow. We show that in the
underparameterized regime the network learns eigenfunctions of an integral
operator $T_{K^\infty}$ determined by the Neural Tangent Kernel (NTK) at rates
corresponding to their eigenvalues. For example, for uniformly distributed data
on the sphere $S^{d - 1}$ and rotation invariant weight distributions, the
eigenfunctions of $T_{K^\infty}$ are the spherical harmonics. Our results can
be understood as describing a spectral bias in the underparameterized regime.
The proofs use the concept of ""Damped Deviations"", where deviations of the NTK
matter less for eigendirections with large eigenvalues due to the occurence of
a damping factor. Aside from the underparameterized regime, the damped
deviations point-of-view can be used to track the dynamics of the empirical
risk in the overparameterized setting, allowing us to extend certain results in
the literature. We conclude that damped deviations offers a simple and unifying
perspective of the dynamics when optimizing the squared error.",2201.04738v1
2022-01-19,Variance-Reduced Stochastic Quasi-Newton Methods for Decentralized Learning: Part II,"In Part I of this work, we have proposed a general framework of decentralized
stochastic quasi-Newton methods, which converge linearly to the optimal
solution under the assumption that the local Hessian inverse approximations
have bounded positive eigenvalues. In Part II, we specify two fully
decentralized stochastic quasi-Newton methods, damped regularized
limited-memory DFP (Davidon-Fletcher-Powell) and damped limited-memory BFGS
(Broyden-Fletcher-Goldfarb-Shanno), to locally construct such Hessian inverse
approximations without extra sampling or communication. Both of the methods use
a fixed moving window of $M$ past local gradient approximations and local
decision variables to adaptively construct positive definite Hessian inverse
approximations with bounded eigenvalues, satisfying the assumption in Part I
for the linear convergence. For the proposed damped regularized limited-memory
DFP, a regularization term is added to improve the performance. For the
proposed damped limited-memory BFGS, a two-loop recursion is applied, leading
to low storage and computation complexity. Numerical experiments demonstrate
that the proposed quasi-Newton methods are much faster than the existing
decentralized stochastic first-order algorithms.",2201.07733v1
2022-01-27,Effect of vertex corrections on the enhancement of Gilbert damping in spin pumping into a two-dimensional electron gas,"We theoretically consider the effect of vertex correction on spin pumping
from a ferromagnetic insulator (FI) into a two-dimensional electron gas (2DEG)
in which the Rashba and Dresselhaus spin-orbit interactions coexist. The
Gilbert damping in the FI is enhanced by elastic spin-flipping or magnon
absorption. We show that the Gilbert damping due to elastic spin-flipping is
strongly enhanced by the vertex correction when the ratio of the two spin-orbit
interactions is near a special value at which the spin relaxation time diverges
while that due to magnon absorption shows only small modification. We also show
that the shift in the resonant frequency due to elastic spin-flipping is
strongly enhanced in a similar way as the Gilbert damping.",2201.11498v3
2022-03-02,Simplified Stability Assessment of Power Systems with Variable-Delay Wide-Area Damping Control,"Power electronic devices such as HVDC and FACTS can be used to improve the
damping of poorly damped inter-area modes in large power systems. This involves
the use of wide-area feedback signals, which are transmitted via communication
networks. The performance of the closed-loop system is strongly influenced by
the delay associated with wide-area signals. The random nature of this delay
introduces a switched linear system model. The stability assessment of such a
system requires linear matrix inequality based approaches. This makes the
stability analysis more complicated as the system size increases. To address
this challenge, this paper proposes a delay-processing strategy that simplifies
the modelling and analysis in discrete-domain. In contrast to the existing
stability assessment techniques, the proposed approach is advantageous because
the stability, as well as damping performance, can be accurately predicted by a
simplified analysis. The proposed methodology is verified with a case study on
the 2-area 4-machine power system with a series compensated tie-line. The
results are found to be in accordance with the predictions of the proposed
simplified analysis.",2203.01362v1
2022-03-03,Forward-modulated damping estimates and nonlocalized stability of periodic Lugiato-Lefever wave,"In an interesting recent analysis, Haragus-Johnson-Perkins-de Rijk have shown
modulational stability under localized perturbations of steady periodic
solutions of the Lugiato-Lefever equation (LLE), in the process pointing out a
difficulty in obtaining standard ""nonlinear damping estimates"" on modulated
perturbation variables to control regularity of solutions. Here, we point out
that in place of standard ""inverse-modulated"" damping estimates, one can
alternatively carry out a damping estimate on the ""forward-modulated""
perturbation, noting that norms of forward- and inverse-modulated variables are
equivalent modulo absorbable errors, thus recovering the classical argument
structure of Johnson-Noble-Rodrigues-Zumbrun for parabolic systems. This
observation seems of general use in situations of delicate regularity.
  Applied in the context of (LLE) it gives the stronger result of stability and
asymptotic behavior with respect to nonlocalized perturbations.",2203.01770v3
2022-03-31,Observing Particle Energization above the Nyquist Frequency: An Application of the Field-Particle Correlation Technique,"The field-particle correlation technique utilizes single-point measurements
to uncover signatures of various particle energization mechanisms in turbulent
space plasmas. The signature of Landau damping by electrons has been found in
both simulations and observations from Earth's magnetosheath using this
technique, but instrumental limitations of spacecraft sampling rates present a
challenge to discovering the full extent of the presence of Landau damping in
the solar wind. Theory predicts that field-particle correlations can recover
velocity-space energization signatures even from data that is undersampled with
respect to the characteristic frequencies at which the wave damping occurs. To
test this hypothesis, we perform a high-resoluation gyrokinetic simulation of
space plasma turbulence, confirm that it contains signatures of electron Landau
damping, and then systematically reduce the time resolution of the data to
identify the point at which the signatures become impossible to recover. We
find results in support of our theoretical prediction and look for a rule of
thumb that can be compared with the measurement capabilities of spacecraft
missions to inform the process of applying field-particle correlations to low
time resolution data.",2204.00104v1
2022-04-06,A Potential Based Quantization Procedure of the Damped Oscillator,"Nowadays, two of the most prospering fields of physics are quantum computing
and spintronics. In both, the loss of information and dissipation plays a
crucial role. In the present work we formulate the quantization of the
dissipative oscillator, which aids understanding of the above mentioned, and
creates a theoretical frame to overcome these issues in the future. Based on
the Lagrangian framework of the damped spring system, the canonically
conjugated pairs and the Hamiltonian of the system are obtained, by which the
quantization procedure can be started and consistently applied. As a result,
the damping quantum wave equation of the dissipative oscillator is deduced, by
which an exact damping wave solution of this equation is obtained.
Consequently, we arrive at such an irreversible quantum theory by which the
quantum losses can be described.",2204.02893v2
2022-04-19,Role of shape anisotropy on thermal gradient-driven domain wall dynamics in magnetic nanowires,"We investigate the magnetic domain wall (DW) dynamics in uniaxial/biaxial
nanowires under a thermal gradient (TG). The findings reveal that the DW
propagates toward the hotter region in both nanowires. The main physics of such
observations is the magnonic angular momentum transfer to the DW. The hard
(shape) anisotropy exists in biaxial nanowire, which contributes an additional
torque, hence DW speed is larger than that in uniaxial nanowire. With lower
damping, the DW velocity is smaller and DW velocity increases with damping
which is opposite to usual expectation. To explain this, it is predicted that
there is a probability to form the standing spin-waves (which do not carry net
energy/momentum) together with travelling spin-waves if the propagation length
of thermally-generated spin-waves is larger than the nanowire length. For
larger-damping, DW decreases with damping since the magnon propagation length
decreases. Therefore, the above findings might be useful in realizing the
spintronic (racetrack memory) devices.",2204.09101v2
2022-04-25,Energy decay estimates for the wave equation with supercritical nonlinear damping,"We consider a damped wave equation in a bounded domain. The damping is
nonlinear and is homogeneous with degree p -- 1 with p > 2. First, we show that
the energy of the strong solution in the supercritical case decays as a
negative power of t; the rate of decay is the same as in the subcritical or
critical cases, provided that the space dimension does not exceed ten. Next,
relying on a new differential inequality, we show that if the initial
displacement is further required to lie in L p , then the energy of the
corresponding weak solution decays logarithmically in the supercritical case.
Those new results complement those in the literature and open an important
breach in the unknown land of super-critical damping mechanisms.",2204.11494v1
2022-05-07,Proposal for a Damping-Ring-Free Electron Injector for Future Linear Colliders,"The current designs of future electron-positron linear colliders incorporate
large and complex damping rings to produce asymmetric beams for beamstrahlung
suppression. Here we present the design of an electron injector capable of
delivering flat electron beams with phase-space partition comparable to the
electron-beam parameters produced downstream of the damping ring in the
proposed international linear collider (ILC) design. Our design does not employ
a damping ring but is instead based on cross-plane phase-space-manipulation
techniques. The performance of the proposed configuration, its sensitivity to
jitter along with its impact on spin-polarization is investigated. The proposed
paradigm could be adapted to other linear collider concepts under consideration
and offers a path toward significant cost and complexity reduction.",2205.03736v1
2022-06-02,Optimal Control of the 3D Damped Navier-Stokes-Voigt Equations with Control Constraints,"In this paper, we consider the 3D Navier-Stokes-Voigt (NSV) equations with
nonlinear damping $|u|^{r-1}u, r\in[1,\infty)$ in bounded and space-periodic
domains. We formulate an optimal control problem of minimizing the curl of the
velocity field in the energy norm subject to the flow velocity satisfying the
damped NSV equation with a distributed control force. The control also needs to
obey box-type constraints. For any $r\geq 1,$ the existence and uniqueness of a
weak solution is discussed when the domain $\Omega$ is periodic/bounded in
$\mathbb R^3$ while a unique strong solution is obtained in the case of
space-periodic boundary conditions. We prove the existence of an optimal pair
for the control problem. Using the classical adjoint problem approach, we show
that the optimal control satisfies a first-order necessary optimality condition
given by a variational inequality. Since the optimal control problem is
non-convex, we obtain a second-order sufficient optimality condition showing
that an admissible control is locally optimal. Further, we derive optimality
conditions in terms of adjoint state defined with respect to the growth of the
damping term for a global optimal control.",2206.00988v2
2022-06-05,Stationary measures for stochastic differential equations with degenerate damping,"A variety of physical phenomena involve the nonlinear transfer of energy from
weakly damped modes subjected to external forcing to other modes which are more
heavily damped. In this work we explore this in (finite-dimensional) stochastic
differential equations in $\mathbb R^n$ with a quadratic, conservative
nonlinearity $B(x,x)$ and a linear damping term $-Ax$ which is degenerate in
the sense that $\mathrm{ker} A \neq \emptyset$. We investigate sufficient
conditions to deduce the existence of a stationary measure for the associated
Markov semigroups. Existence of such measures is straightforward if $A$ is full
rank, but otherwise, energy could potentially accumulate in $\mathrm{ker} A$
and lead to almost-surely unbounded trajectories, making the existence of
stationary measures impossible. We give a relatively simple and general
sufficient condition based on time-averaged coercivity estimates along
trajectories in neighborhoods of $\mathrm{ker} A$ and many examples where such
estimates can be made.",2206.02240v1
2022-06-17,Resolvent estimates for the one-dimensional damped wave equation with unbounded damping,"We study the generator $G$ of the one-dimensional damped wave equation with
unbounded damping. We show that the norm of the corresponding resolvent
operator, $\| (G - \lambda)^{-1} \|$, is approximately constant as $|\lambda|
\to +\infty$ on vertical strips of bounded width contained in the closure of
the left-hand side complex semi-plane, $\overline{\mathbb{C}}_{-} := \{\lambda
\in \mathbb{C}: \operatorname{Re} \lambda \le 0\}$. Our proof rests on a
precise asymptotic analysis of the norm of the inverse of $T(\lambda)$, the
quadratic operator associated with $G$.",2206.08820v2
2022-07-13,Energy decay for the time dependent damped wave equation,"Energy decay is established for the damped wave equation on compact
Riemannian manifolds where the damping coefficient is allowed to depend on
time. Using a time dependent observability inequality, it is shown that the
energy of solutions decays at an exponential rate if the damping coefficient
satisfies a time dependent analogue of the classical geometric control
condition. Existing time dependent observability inequalities are improved by
removing technical assumptions on the permitted initial data.",2207.06260v4
2022-08-04,Lp-asymptotic stability of 1D damped wave equations with localized and nonlinear damping,"In this paper, we study the $L^p$-asymptotic stability with $p\in (1,\infty)$
of the one-dimensional nonlinear damped wave equation with a localized damping
and Dirichlet boundary conditions in a bounded domain $(0,1)$. We start by
addressing the well-posedness problem. We prove the existence and the
uniqueness of weak solutions for $p\in [2,\infty)$ and the existence and the
uniqueness of strong solutions for all $p\in [1,\infty)$. The proofs rely on
the well-posedness already proved in the $L^\infty$ framework by [4] combined
with a density argument. Then we prove that the energy of strong solutions
decays exponentially to zero. The proof relies on the multiplier method
combined with the work that has been done in the linear case in [8].",2208.02779v1
2022-08-07,"Damping of neutrino oscillations, decoherence and the lengths of neutrino wave packets","Spatial separation of the wave packets (WPs) of neutrino mass eigenstates
leads to decoherence and damping of neutrino oscillations. Damping can also be
caused by finite energy resolution of neutrino detectors or, in the case of
experiments with radioactive neutrino sources, by finite width of the emitted
neutrino line. We study in detail these two types of damping effects using
reactor neutrino experiments and experiments with radioactive $^{51}$Cr source
as examples. We demonstrate that the effects of decoherence by WP separation
can always be incorporated into a modification of the energy resolution
function of the detector and so are intimately entangled with it. We estimate
for the first time the lengths $\sigma_x$ of WPs of reactor neutrinos and
neutrinos from a radioactive $^{51}$Cr source. The obtained values, $\sigma_x =
(2\times 10^{-5} - 1.4\times 10^{-4})$ cm, are at least six orders of magnitude
larger than the currently available experimental lower bounds. We conclude that
effects of decoherence by WP separation cannot be probed in reactor and
radioactive source experiments.",2208.03736v2
2022-08-23,Fate of exceptional points in the presence of nonlinearities,"The non-Hermitian dynamics of open systems deal with how intricate coherent
effects of a closed system intertwine with the impact of coupling to an
environment. The system-environment dynamics can then lead to so-called
exceptional points, which are the open-system marker of phase transitions,
i.e., the closing of spectral gaps in the complex spectrum. Even in the
ubiquitous example of the damped harmonic oscillator, the dissipative
environment can lead to an exceptional point, separating between under-damped
and over-damped dynamics at a point of critical damping. Here, we examine the
fate of this exceptional point in the presence of strong correlations, i.e.,
for a nonlinear oscillator. By employing a functional renormalization group
approach, we identify non-perturbative regimes of this model where the
nonlinearity makes the system more robust against the influence of dissipation
and can remove the exceptional point altogether. The melting of the exceptional
point occurs above a critical nonlinearity threshold. Interestingly, the
exceptional point melts faster with increasing temperatures, showing a
surprising flow to coherent dynamics when coupled to a warm environment.",2208.11205v2
2022-09-10,"Data-driven, multi-moment fluid modeling of Landau damping","Deriving governing equations of complex physical systems based on first
principles can be quite challenging when there are certain unknown terms and
hidden physical mechanisms in the systems. In this work, we apply a deep
learning architecture to learn fluid partial differential equations (PDEs) of a
plasma system based on the data acquired from a fully kinetic model. The
learned multi-moment fluid PDEs are demonstrated to incorporate kinetic effects
such as Landau damping. Based on the learned fluid closure, the data-driven,
multi-moment fluid modeling can well reproduce all the physical quantities
derived from the fully kinetic model. The calculated damping rate of Landau
damping is consistent with both the fully kinetic simulation and the linear
theory. The data-driven fluid modeling of PDEs for complex physical systems may
be applied to improve fluid closure and reduce the computational cost of
multi-scale modeling of global systems.",2209.04726v1
2022-09-25,Formation of the cosmic-ray halo: The role of nonlinear Landau damping,"We present a nonlinear model of self-consistent Galactic halo, where the
processes of cosmic ray (CR) propagation and excitation/damping of MHD waves
are included. The MHD-turbulence, which prevents CR escape from the Galaxy, is
entirely generated by the resonant streaming instability. The key mechanism
controlling the halo size is the nonlinear Landau (NL) damping, which
suppresses the amplitude of MHD fluctuations and, thus, makes the halo larger.
The equilibrium turbulence spectrum is determined by a balance of CR excitation
and NL damping, which sets the regions of diffusive and advective propagation
of CRs. The boundary $z_{cr}(E)$ between the two regions is the halo size,
which slowly increases with the energy. For the vertical magnetic field of
$\sim 1~\mu G$, we estimate $z_{cr} \sim 1$ kpc for GeV protons. The derived
proton spectrum is in a good agreement with observational data.",2209.12302v1
2022-10-10,Finite time extinction for a critically damped Schr{ö}dinger equation with a sublinear nonlinearity,"This paper completes some previous studies by several authors on the finite
time extinction for nonlinear Schr{\""o}dinger equation when the nonlinear
damping term corresponds to the limit cases of some ``saturating non-Kerr law''
$F(|u|^2)u=\frac{a}{\varepsilon+(|u|^2)^\alpha}u,$ with $a\in\mathbb{C},$
$\varepsilon\geqslant0,$ $2\alpha=(1-m)$ and $m\in[0,1).$ Here we consider the
sublinear case $0<m<1$ with a critical damped coefficient: $a\in\mathbb{C}$ is
assumed to be in the set $D(m)=\big\{z\in\mathbb{C}; \; \mathrm{Im}(z)>0 \text{
and } 2\sqrt{m}\mathrm{Im}(z)=(1-m)\mathrm{Re}(z)\big\}.$ Among other things,
we know that this damping coefficient is critical, for instance, in order to
obtain the monotonicity of the associated operator (see the paper by Liskevich
and Perel'muter [16] and the more recent study by Cialdea and Maz'ya [14]). The
finite time extinction of solutions is proved by a suitable energy method after
obtaining appropiate a priori estimates. Most of the results apply to
non-necessarily bounded spatial domains.",2210.04493v4
2022-10-14,Landau damping for gravitational waves in parity-violating theories,"We discuss how tensor polarizations of gravitational waves can suffer Landau
damping in the presence of velocity birefringence, when parity symmetry is
explicitly broken. In particular, we analyze the role of the Nieh-Yan and
Chern-Simons terms in modified theories of gravity, showing how the
gravitational perturbation in collisionless media can be characterized by a
subluminal phase velocity, circumventing the well-known results of General
Relativity and allowing for the appearance of the kinematic damping. We
investigate in detail the connection between the thermodynamic properties of
the medium, such as temperature and mass of the particles interacting with the
gravitational wave, and the parameters ruling the parity violating terms of the
models. In this respect, we outline how the dispersion relations can give rise
in each model to different regions of the wavenumber space, where the phase
velocity is subluminal, superluminal or does not exist. Quantitative estimates
on the considered models indicate that the phenomenon of Landau damping is not
detectable given the sensitivity of present-day instruments.",2210.07673v2
2022-10-25,Formation of shifted shock for the 3D compressible Euler equations with damping,"In this paper, we show the shock formation of the solutions to the
3-dimensional (3D) compressible isentropic and irrotational Euler equations
with damping for the initial short pulse data which was first introduced by
D.Christodoulou\cite{christodoulou2007}. Due to the damping effect, the
largeness of the initial data is necessary for the shock formation and we will
work on the class of large data (in energy sense). Similar to the undamped
case, the formation of shock is characterized by the collapse of the
characteristic hypersurfaces and the vanishing of the inverse foliation density
function $\mu$, at which the first derivatives of the velocity and the density
blow up. However, the damping effect changes the asymptotic behavior of the
inverse foliation density function $\mu$ and then shifts the time of shock
formation compared with the undamped case. The methods in the paper can also be
extended to a class of $3D$ quasilinear wave equations for the short pulse
initial data.",2210.13796v1
2022-10-30,Dynamics of a class of extensible beams with degenerate and non-degenerate nonlocal damping,"This work is concerned with new results on long-time dynamics of a class of
hyperbolic evolution equations related to extensible beams with three
distinguished nonlocal nonlinear damping terms. In the first possibly
degenerate case, the results feature the existence of a family of compact
global attractors and a thickness estimate for their Kolmogorov's
$\varepsilon$-entropy. Then, in the non-degenerate context, the structure of
the helpful nonlocal damping leads to the existence of finite-dimensional
compact global and exponential attractors. Lastly, in a degenerate and critical
framework, it is proved the existence of a bounded closed global attractor but
not compact. To the proofs, we provide several new technical results by means
of refined estimates that open up perspectives for a new branch of nonlinearly
damped problems.",2210.16851v1
2022-11-11,Nonlinear fractional damped wave equation on compact Lie groups,"In this paper, we deal with the initial value fractional damped wave equation
on $G$, a compact Lie group, with power-type nonlinearity. The aim of this
manuscript is twofold. First, using the Fourier analysis on compact Lie groups,
we prove a local in-time existence result in the energy space for the
fractional damped wave equation on $G$. Moreover, a finite time blow-up result
is established under certain conditions on the initial data. In the next part
of the paper, we consider fractional wave equation with lower order terms, that
is, damping and mass with the same power type nonlinearity on compact Lie
groups, and prove the global in-time existence of small data solutions in the
energy evolution space.",2211.06155v1
2022-11-16,Controlling the motional quality factor of a diamagnetically levitated graphite plate,"Researchers seek methods to levitate matter for a wide variety of purposes,
ranging from exploring fundamental problems in science, through to developing
new sensors and mechanical actuators. Many levitation techniques require active
driving and most can only be applied to objects smaller than a few micrometers.
Diamagnetic levitation has the strong advantage of being the only form of
levitation which is passive, requiring no energy input, while also supporting
massive objects. Known diamagnetic materials which are electrical insulators
are only weakly diamagnetic, and require large magnetic field gradients to
levitate. Strong diamagnetic materials which are electrical conductors, such as
graphite, exhibit eddy damping, restricting motional freedom and reducing their
potential for sensing applications. In this work we describe a method to
engineer the eddy damping while retaining the force characteristics provided by
the diamagnetic material. We study, both experimentally and theoretically, the
motional damping of a magnetically levitated graphite plate in high vacuum and
demonstrate that one can control the eddy damping by patterning the plate with
through-slots which interrupt the eddy currents. We find we can control the
motional quality factor over a wide range with excellent agreement between the
experiment and numerical simulations.",2211.08764v1
2022-12-03,Strong On-Chip Microwave Photon-Magnon Coupling Using Ultra-low Damping Epitaxial Y3Fe5O12 Films at 2 Kelvin,"Y3Fe5O12 is arguably the best magnetic material for magnonic quantum
information science (QIS) because of its extremely low damping. We report
ultralow damping at 2 K in epitaxial Y3Fe5O12 thin films grown on a diamagnetic
Y3Sc2Ga3O12 substrate that contains no rare-earth elements. Using these
ultralow damping YIG films, we demonstrate for the first time strong coupling
between magnons in patterned YIG thin films and microwave photons in a
superconducting Nb resonator. This result paves the road towards scalable
hybrid quantum systems that integrate superconducting microwave resonators, YIG
film magnon conduits, and superconducting qubits into on-chip QIS devices.",2212.01708v1
2022-12-21,Fractional damping effects on the transient dynamics of the Duffing oscillator,"We consider the nonlinear Duffing oscillator in presence of fractional
damping which is characteristic in different physical situations. The system is
studied with a smaller and larger damping parameter value, that we call the
underdamped and overdamped regimes. In both we have studied the relation
between the fractional parameter, the amplitude of the oscillations and the
times to reach the asymptotic behavior, called asymptotic times. In the
overdamped regime, the study shows that, also here, there are oscillations for
fractional order derivatives and their amplitudes and asymptotic times can
suddenly change for small variations of the fractional parameter. In addition,
in this latter regime, a resonant-like behavior can take place for suitable
values of the parameters of the system. These results are corroborated by
calculating the corresponding Q-factor. We expect that these results can be
useful for a better understanding of fractional dynamics and its possible
applications as in modeling different kind of materials that normally need
complicated damping terms.",2212.11023v1
2023-01-02,Fast convex optimization via closed-loop time scaling of gradient dynamics,"In a Hilbert setting, for convex differentiable optimization, we develop a
general framework for adaptive accelerated gradient methods. They are based on
damped inertial dynamics where the coefficients are designed in a closed-loop
way. Specifically, the damping is a feedback control of the velocity, or of the
gradient of the objective function. For this, we develop a closed-loop version
of the time scaling and averaging technique introduced by the authors. We thus
obtain autonomous inertial dynamics which involve vanishing viscous damping and
implicit Hessian driven damping. By simply using the convergence rates for the
continuous steepest descent and Jensen's inequality, without the need for
further Lyapunov analysis, we show that the trajectories have several
remarkable properties at once: they ensure fast convergence of values, fast
convergence of the gradients towards zero, and they converge to optimal
solutions. Our approach leads to parallel algorithmic results, that we study in
the case of proximal algorithms. These are among the very first general results
of this type obtained using autonomous dynamics.",2301.00701v1
2023-01-19,Damped harmonic oscillator revisited: the fastest route to equilibrium,"Theoretically, solutions of the damped harmonic oscillator asymptotically
approach equilibrium, i.e., the zero energy state, without ever reaching it
exactly, and the critically damped solution approaches equilibrium faster than
the underdamped or the overdamped solution. Experimentally, the systems
described with this model reach equilibrium when the system's energy has
dropped below some threshold corresponding to the energy resolution of the
measuring apparatus. We show that one can (almost) always find an optimal
underdamped solution that will reach this energy threshold sooner than all
other underdamped solutions, as well as the critically damped solution, no
matter how small this threshold is. We also comment on one exception to this
for a particular type of initial conditions, when a specific overdamped
solution reaches the equilibrium state sooner than all other solutions. We
confirm some of our findings experimentally.",2301.08222v2
2023-01-22,Boundary stabilization of a vibrating string with variable length,"We study small vibrations of a string with time-dependent length $\ell(t)$
and boundary damping. The vibrations are described by a 1-d wave equation in an
interval with one moving endpoint at a speed $\ell'(t)$ slower than the speed
of propagation of the wave c=1. With no damping, the energy of the solution
decays if the interval is expanding and increases if the interval is shrinking.
The energy decays faster when the interval is expanding and a constant damping
is applied at the moving end. However, to ensure the energy decay in a
shrinking interval, the damping factor $\eta$ must be close enough to the
optimal value $\eta=1$, corresponding to the transparent condition. In all
cases, we establish lower and upper estimates for the energy with explicit
constants.",2301.09086v1
2023-02-24,Asymptotic behaviour of the semidiscrete FE approximations to weakly damped wave equations with minimal smoothness on initial data,"Exponential decay estimates of a general linear weakly damped wave equation
are studied with decay rate lying in a range. Based on the $C^0$-conforming
finite element method to discretize spatial variables keeping temporal variable
continuous, a semidiscrete system is analysed, and uniform decay estimates are
derived with precisely the same decay rate as in the continuous case. Optimal
error estimates with minimal smoothness assumptions on the initial data are
established, which preserve exponential decay rate, and for a 2D problem, the
maximum error bound is also proved. The present analysis is then generalized to
include the problems with non-homogeneous forcing function, space-dependent
damping, and problems with compensator. It is observed that decay rates are
improved with large viscous damping and compensator. Finally, some numerical
experiments are performed to validate the theoretical results established in
this paper.",2302.12476v1
2023-02-27,Nonlinear acoustic imaging with damping,"In this paper, we consider an inverse problem for a nonlinear wave equation
with a damping term and a general nonlinear term. This problem arises in
nonlinear acoustic imaging and has applications in medical imaging and other
fields. The propagation of ultrasound waves can be modeled by a quasilinear
wave equation with a damping term. We show the boundary measurements encoded in
the Dirichlet-to-Neumann map (DN map) determine the damping term and the
nonlinearity at the same time. In a more general setting, we consider a
quasilinear wave equation with a one-form (a first-order term) and a general
nonlinear term. We prove the one-form and the nonlinearity can be determined
from the DN map, up to a gauge transformation, under some assumptions.",2302.14174v1
2023-04-11,Sizable suppression of magnon Hall effect by magnon damping in Cr$_2$Ge$_2$Te$_6$,"Two-dimensional (2D) Heisenberg honeycomb ferromagnets are expected to have
interesting topological magnon effects as their magnon dispersion can have
Dirac points. The Dirac points are gapped with finite second nearest neighbor
Dzyaloshinskii-Moriya interaction, providing nontrivial Berry curvature with
finite magnon Hall effect. Yet, it is unknown how the topological properties
are affected by magnon damping. We report the thermal Hall effect in
Cr$_2$Ge$_2$Te$_6$, an insulating 2D honeycomb ferromagnet with a large Dirac
magnon gap and significant magnon damping. Interestingly, the thermal Hall
conductivity in Cr$_2$Ge$_2$Te$_6$ shows the coexisting phonon and magnon
contributions. Using an empirical two-component model, we successfully estimate
the magnon contribution separate from the phonon part, revealing that the
magnon Hall conductivity was 20 times smaller than the theoretical calculation.
Finally, we suggest that such considerable suppression in the magnon Hall
conductivity is due to the magnon damping effect in Cr$_2$Ge$_2$Te$_6$.",2304.04922v1
2023-04-22,Video analysis of the damped oscillations of Pohl's pendulum,"In this paper problems that arose with the introduction of distance learning
in physics at the Technical University of Sofia due to the COVID-19 pandemic
and the imposition of video recording of laboratory exercises are indicated. It
was found that the video for the ''Damped Mechanical Oscillations'' exercise
provides enough information for a more detailed and in-depth analysis of the
studied phenomenon compared to the standard way of capturing the data. The
Video Editor program was used to view the video frame by frame and statistical
processing - non-linear regression - was performed with the recorded data. The
laboratory results are compared with the theoretical function, the parameters
of which are optimized as a result of the specified processing. A theoretical
model of the damped oscillation is described and the dependence of the damping
coefficient on the current through the electromagnetic brake is theoretically
investigated.",2304.11390v1
2023-05-22,Semi-active damping optimization of vibrational systems using the reduced basis method,"In this article, we consider vibrational systems with semi-active damping
that are described by a second-order model. In order to minimize the influence
of external inputs to the system response, we are optimizing some damping
values. As minimization criterion, we evaluate the energy response, that is the
$\cH_2$-norm of the corresponding transfer function of the system. Computing
the energy response includes solving Lyapunov equations for different damping
parameters. Hence, the minimization process leads to high computational costs
if the system is of large dimension. We present two techniques that reduce the
optimization problem by applying the reduced basis method to the corresponding
parametric Lyapunov equations. In the first method, we determine a reduced
solution space on which the Lyapunov equations and hence the resulting energy
response values are computed approximately in a reasonable time. The second
method includes the reduced basis method in the minimization process. To
evaluate the quality of the approximations, we introduce error estimators that
evaluate the error in the controllability Gramians and the energy response.
Finally, we illustrate the advantages of our methods by applying them to two
different examples.",2305.12946v1
2023-06-01,A combined volume penalization / selective frequency damping approach for immersed boundary methods: application to moving geometries,"This work extends, to moving geometries, the immersed boundary method based
on volume penalization and selective frequency damping approach [J. Kou, E.
Ferrer, A combined volume penalization/selective frequency damping approach for
immersed boundary methods applied to high-order schemes, Journal of
Computational Physics (2023)]. To do so, the numerical solution inside the
solid is decomposed into a predefined movement and an oscillatory part
(spurious waves), where the latter is damped by an SFD approach combined with
volume penalization. We challenge the method with two cases. First, a new
manufactured solution problem is proposed to show that the method can recover
high-order accuracy. Second, we validate the methodology by simulating the
laminar flow past a moving cylinder, where improved accuracy of the combined
method is reported.",2306.00504v1
2023-06-09,Damped nonlinear Schrödinger equation with Stark effect,"We study the $L^2$-critical damped NLS with a Stark potential. We prove that
the threshold for global existence and finite time blowup of this equation is
given by $\|Q\|_2$, where $Q$ is the unique positive radial solution of $\Delta
Q + |Q|^{4/d} Q = Q$ in $H^1(\mathbb{R}^d)$. Moreover, in any small
neighborhood of $Q$, there exists an initial data $u_0$ above the ground state
such that the solution flow admits the log-log blowup speed. This verifies the
structural stability for the ``$\log$-$\log$ law'' associated to the NLS
mechanism under the perturbation by a damping term and a Stark potential. The
proof of our main theorem is based on the Avron-Herbst formula and the
analogous result for the unperturbed damped NLS.",2306.05931v1
2023-06-19,New Perspectives and Systematic Approaches for Analyzing Negative Damping-Induced Sustained Oscillation,"Sustained oscillations (SOs) are commonly observed in systems dominated by
converters. Under specific conditions, even though the origin of SOs can be
identified through negative damping modes using conventional linear analysis,
utilizing the describing function to compute harmonic amplitude and frequency
remains incomplete. This is because a) it can not cover the cases where hard
limits are not triggered, and b) it can not provide a complete trajectory for
authentic linear analysis to confirm the presence of SO. Hence, two analytical
methods are proposed by returning to the essential principle of harmonic
balance. a) A dedicated approach is proposed to solving steady-state harmonics
via Newton-Raphson iteration with carefully chosen initial values. The method
encompasses all potential hard limit triggered cases. b) By employing extended
multiharmonic linearization theory and considering loop impedance, an authentic
linear analysis of SO is conducted. The analysis indicates that the initial
negative damping modes transform into multiple positive damping modes as SO
develops. Simulation validations are performed on a two-level voltage source
converter using both PSCAD and RT-LAB. Additionally, valuable insights into the
work are addressed considering the modularity and scalability of the proposed
methods.",2306.10839v2
2023-06-24,Numerical approximation of the invariant distribution for a class of stochastic damped wave equations,"We study a class of stochastic semilinear damped wave equations driven by
additive Wiener noise. Owing to the damping term, under appropriate conditions
on the nonlinearity, the solution admits a unique invariant distribution. We
apply semi-discrete and fully-discrete methods in order to approximate this
invariant distribution, using a spectral Galerkin method and an exponential
Euler integrator for spatial and temporal discretization respectively. We prove
that the considered numerical schemes also admit unique invariant
distributions, and we prove error estimates between the approximate and exact
invariant distributions, with identification of the orders of convergence. To
the best of our knowledge this is the first result in the literature concerning
numerical approximation of invariant distributions for stochastic damped wave
equations.",2306.13998v1
2023-07-31,Estimation of Power in the Controlled Quantum Teleportation through the Witness Operator,"Controlled quantum teleportation (CQT) can be considered as a variant of
quantum teleportation in which three parties are involved where one party acts
as the controller. The usability of the CQT scheme depends on two types of
fidelities viz. conditioned fidelity and non-conditioned fidelity. The
difference between these fidelities may be termed as power of the controller
and it plays a vital role in the CQT scheme. Thus, our aim is to estimate the
power of the controller in such a way so that its estimated value can be
obtained in an experiment. To achieve our goal, we have constructed a witness
operator and have shown that its expected value may be used in the estimation
of the lower bound of the power of the controller. Furthermore, we have shown
that it is possible to make the standard W state useful in the CQT scheme if
one of its qubits either passes through the amplitude damping channel or the
phase damping channel. We have also shown that the phase damping channel
performs better than the amplitude damping channel in the sense of generating
more power of the controller in the CQT scheme.",2307.16574v1
2023-08-03,Triple-Spherical Bessel Function Integrals with Exponential and Gaussian Damping: Towards an Analytic N-Point Correlation Function Covariance Model,"Spherical Bessel functions appear commonly in many areas of physics wherein
there is both translation and rotation invariance, and often integrals over
products of several arise. Thus, analytic evaluation of such integrals with
different weighting functions (which appear as toy models of a given physical
observable, such as the galaxy power spectrum) is useful. Here we present a
generalization of a recursion-based method for evaluating such integrals. It
gives relatively simple closed-form results in terms of Legendre functions (for
the exponentially-damped case) and Gamma, incomplete Gamma functions, and
hypergeometric functions (for the Gaussian-damped case). We also present a new,
non-recursive method to evaluate integrals of products of spherical Bessel
functions with Gaussian damping in terms of incomplete Gamma functions and
hypergeometric functions.",2308.01955v2
2023-08-28,Quantized damped transversal single particle mechanical waves,"In information transfer, the dissipation of a signal may have crucial
importance. The feasibility of reconstructing the distorted signal also depends
on this. That is why the study of quantized dissipative transversal single
particle mechanical waves may have an important role. It may be true,
particularly on the nanoscale in the case of signal distortion, loss, or
restoration. Based on the damped oscillator quantum description, we generalize
the canonical quantization procedure for the transversal waves. Furthermore, we
deduce the related damped wave equation and the state function. We point out
the two kinds of solutions of the wave equation. One involves the well-known
spreading solution superposed with the oscillation, in which the loss of
information is complete. The other is the Airy function solution, which is
non-spreading, so there is information loss only due to oscillation damping.
However, the structure of the wavefront remains unchanged. Thus, this result
allows signal reconstruction, which is important in restoring the lost
information.",2308.14820v1
2023-11-15,Integrated Local Energy Decay for Damped Magnetic Wave Equations on Stationary Space-Times,"We establish local energy decay for damped magnetic wave equations on
stationary, asymptotically flat space-times subject to the geometric control
condition. More specifically, we allow for the addition of time-independent
magnetic and scalar potentials, which negatively affect energy coercivity and
may add in unwieldy spectral effects. By asserting the non-existence of
eigenvalues in the lower half-plane and resonances on the real line, we are
able to apply spectral theory from the work of Metcalfe, Sterbenz, and Tataru
and combine with a generalization of prior work by the present author to extend
the latter work and establish local energy decay, under one additional symmetry
hypothesis. Namely, we assume that either the imaginary part of the magnetic
potentials are uniformly small or, more interestingly and novelly, that the
damping term is the dominant principal term in the skew-adjoint part of the
damped wave operator within the region where the metric perturbation from that
of Minkowski space is permitted to be large. We also obtain an energy dichotomy
if we do not prohibit non-zero real resonances. In order to make the structure
of the argument more cohesive, we contextualize the present work within
requisite existing theory.",2311.08628v1
2023-11-15,Applications of $L^p-L^q$ estimates for solutions to semi-linear $σ$-evolution equations with general double damping,"In this paper, we would like to study the linear Cauchy problems for
semi-linear $\sigma$-evolution models with mixing a parabolic like damping term
corresponding to $\sigma_1 \in [0,\sigma/2)$ and a $\sigma$-evolution like
damping corresponding to $\sigma_2 \in (\sigma/2,\sigma]$. The main goals are
on the one hand to conclude some estimates for solutions and their derivatives
in $L^q$ setting, with any $q\in [1,\infty]$, by developing the theory of
modified Bessel functions effectively to control oscillating integrals
appearing the solution representation formula in a competition between these
two kinds of damping. On the other hand, we are going to prove the global (in
time) existence of small data Sobolev solutions in the treatment of the
corresponding semi-linear equations by applying $(L^{m}\cap L^{q})- L^{q}$ and
$L^{q}- L^{q}$ estimates, with $q\in (1,\infty)$ and $m\in [1,q)$, from the
linear models. Finally, some further generalizations will be discussed in the
end of this paper.",2311.09085v1
2023-11-23,"Friction of a driven chain: Role of momentum conservation, Goldstone and radiation modes","We analytically study friction and dissipation of a driven bead in a 1D
harmonic chain, and analyze the role of internal damping mechanism as well as
chain length. Specifically, we investigate Dissipative Particle Dynamics and
Langevin Dynamics, as paradigmatic examples that do and do not display
translational symmetry, with distinct results: For identical parameters, the
friction forces can differ by many orders of magnitude. For slow driving, a
Goldstone mode traverses the entire system, resulting in friction of the driven
bead that grows arbitrarily large (Langevin) or gets arbitrarily small
(Dissipative Particle Dynamics) with system size. For a long chain, the
friction for DPD is shown to be bound, while it shows a singularity (i.e. can
be arbitrarily large) for Langevin damping. For long underdamped chains, a
radiation mode is recovered in either case, with friction independent of
damping mechanism. For medium length chains, the chain shows the expected
resonant behavior. At the resonance, friction is non-analytic in damping
parameter $\gamma$, depending on it as $\gamma^{-1}$. Generally, no zero
frequency bulk friction coefficient can be determined, as the limits of small
frequency and infinite chain length do not commute, and we discuss the regimes
where ""simple"" macroscopic friction occurs.",2311.14075v1
2023-12-07,Generalized Damping Torque Analysis of Ultra-Low Frequency Oscillation in the Jerk Space,"Ultra low frequency oscillation (ULFO) is significantly threatening the power
system stability. Its unstable mechanism is mostly studied via generalized
damping torque analysis method (GDTA). However, the analysis still adopts the
framework established for low frequency oscillation. Hence, this letter
proposes a GDTA approach in the jerk space for ULFO. A multi-information
variable is constructed to transform the system into a new state space, where
it is found that the jerk dynamics of the turbine-generator cascaded system is
a second-order differential equation. Benefiting from this characteristic, we
propose a new form for GDTA using jerk dynamics, which is established in the
frequency-frequency acceleration phase space. Then, analytical expressions of
all damping torque are provided. Finally, test results verified the proposed
theoretical results. The negative damping mechanism is revealed, and parameter
adjustment measures are concluded.",2312.04148v1
2023-12-08,Selective damping of plasmons in coupled two-dimensional systems by Coulomb drag,"The Coulomb drag is a many-body effect observed in proximized low-dimensional
systems. It appears as emergence of voltage in one of them upon passage of bias
current in another. The magnitude of drag voltage can be strongly affected by
exchange of plasmonic excitations between the layers; however, the reverse
effect of Coulomb drag on properties of plasmons has not been studied. Here, we
study the plasmon spectra and damping in parallel two-dimensional systems in
the presence of Coulomb drag. We find that Coulomb drag leads to selective
damping of one of the two fundamental plasma modes of a coupled bilayer. For
identical electron doping of both layers, the drag suppresses the acoustic
plasma mode; while for symmetric electron-hole doping of the coupled pair, the
drag suppresses the optical plasma mode. The selective damping can be observed
both for propagating modes in extended bilayers and for localized plasmons in
bilayers confined by source and drain contacts. The discussed effect may
provide access to the strength of Coulomb interaction in 2d electron systems
from various optical and microwave scattering experiments.",2312.05097v1
2023-12-13,Geometrical Interpretation of Neutrino Oscillation with decay,"The geometrical representation of two-flavor neutrino oscillation represents
the neutrino's flavor eigenstate as a magnetic moment-like vector that evolves
around a magnetic field-like vector that depicts the Hamiltonian of the system.
In the present work, we demonstrate the geometrical interpretation of neutrino
in a vacuum in the presence of decay, which transforms this circular trajectory
of neutrino into a helical track that effectively makes the neutrino system
mimic a classical damped driven oscillator. We show that in the absence of the
phase factor $\xi$ in the decay Hamiltonian, the neutrino exactly behaves like
the system of nuclear magnetic resonance(NMR); however, the inclusion of the
phase part introduces a $CP$ violation, which makes the system deviate from
NMR. Finally, we make a qualitative discussion on under-damped,
critically-damped, and over-damped scenarios geometrically by three different
diagrams. In the end, we make a comparative study of geometrical picturization
in vacuum, matter, and decay, which extrapolates the understanding of the
geometrical representation of neutrino oscillation in a more straightforward
way.",2312.08178v1
2023-12-14,Smoluchowski-Kramers diffusion approximation for systems of stochastic damped wave equations with non-constant friction,"We consider systems of damped wave equations with a state-dependent damping
coefficient and perturbed by a Gaussian multiplicative noise. Initially, we
investigate their well-posedness, under quite general conditions on the
friction. Subsequently, we study the validity of the so-called
Smoluchowski-Kramers diffusion approximation. We show that, under more
stringent conditions on the friction, in the small-mass limit the solution of
the system of stochastic damped wave equations converges to the solution of a
system of stochastic quasi-linear parabolic equations. In this convergence, an
additional drift emerges as a result of the interaction between the noise and
the state-dependent friction. The identification of this limit is achieved by
using a suitable generalization of the classical method of perturbed test
functions, tailored to the current infinite dimensional setting.",2312.08925v1
2023-12-28,Cause-effect relationship between model parameters and damping performance of hydraulic shock absorbers,"Despite long-term research and development of modern shock absorbers, the
effect of variations of several crucial material and model parameters still
remains dubious. The goal of this work is therefore a study of the changes of
shock absorber dynamics with respect to typical parameter ranges in a realistic
model. We study the impact of shim properties, as well as geometric features
such as discharge coefficients and bleed orifice cross section. We derive
cause-effect relationships by nonlinear parameter fitting of the differential
equations of the model and show digressive and progressive quadratic damping
curves for shim number and thickness, sharp exponential curves for discharge
coefficients, and leakage width, as well as a linear decrease of damping
properties with bleed orifice area. Temperature increase affecting material
properties, such as density and viscosity of the mineral oil, is found to have
a mostly linear relationship with damping and pressure losses. Our results are
not only significant for the general understanding of shock absorber dynamics,
but also serve as a guidance for the development of specific models by
following the proposed methodology.",2312.17175v1
2024-01-01,Magnon Damping Minimum and Logarithmic Scaling in a Kondo-Heisenberg Model,"Recently, an anomalous temperature evolution of spin wave excitations has
been observed in a van der Waals metallic ferromagnet Fe$_3$GeTe$_2$ (FGT) [S.
Bao, et al., Phys. Rev. X 12, 011022 (2022)], whose theoretical understanding
yet remains elusive. Here we study the spin dynamics of a ferromagnetic
Kondo-Heisenberg lattice model at finite temperature, and propose a mechanism
of magnon damping that explains the intriguing experimental results. In
particular, we find the magnon damping rate $\gamma(T)$ firstly decreases as
temperature lowers, due to the reduced magnon-magnon scatterings. It then
reaches a minimum at $T_{\rm d}^*$, and rises up again following a logarithmic
scaling $\gamma(T) \sim \ln{(T_0/T)}$ (with $T_0$ a constant) for $T < T_{\rm
d}^*$, which can be attributed to electron-magnon scatterings of spin-flip
type. Moreover, we obtain the phase diagram containing the ferromagnetic and
Kondo insulator phases by varying the Kondo coupling, which may be relevant for
experiments on pressured FGT. The presence of a magnon damping minimum and
logarithmic scaling at low temperature indicates the emergence of the Kondo
effect reflected in the collective excitations of local moments in a Kondo
lattice system.",2401.00758v1
2024-01-04,Simplified Information Geometry Approach for Massive MIMO-OFDM Channel Estimation -- Part II: Convergence Analysis,"In Part II of this two-part paper, we prove the convergence of the simplified
information geometry approach (SIGA) proposed in Part I. For a general Bayesian
inference problem, we first show that the iteration of the common second-order
natural parameter (SONP) is separated from that of the common first-order
natural parameter (FONP). Hence, the convergence of the common SONP can be
checked independently. We show that with the initialization satisfying a
specific but large range, the common SONP is convergent regardless of the value
of the damping factor. For the common FONP, we establish a sufficient condition
of its convergence and prove that the convergence of the common FONP relies on
the spectral radius of a particular matrix related to the damping factor. We
give the range of the damping factor that guarantees the convergence in the
worst case. Further, we determine the range of the damping factor for massive
MIMO-OFDM channel estimation by using the specific properties of the
measurement matrices. Simulation results are provided to confirm the
theoretical results.",2401.02037v1
2024-01-04,A Pure Integral-Type PLL with a Damping Branch to Enhance the Stability of Grid-Tied Inverter under Weak Grids,"In a phase-locked loop (PLL) synchronized inverter, due to the strong
nonlinear coupling between the PLL's parame-ters and the operation power angle,
the equivalent damping coefficient will quickly deteriorate while the power
angle is close to 90{\deg} under an ultra-weak grid, which causes the
synchronous instability. To address this issue, in this letter, a pure
integral-type phase-locked loop (IPLL) with a damping branch is proposed to
replace the traditional PI-type PLL. The equivalent damping coefficient of an
IPLL-synchronized inverter is decoupled with the steady-state power angle. As a
result, the IPLL-synchronized inverter can stably operate under an ultra-weak
grid when the equilibrium point exists. Finally, time-domain simulation results
verify the effectiveness and correctness of the proposed IPLL.",2401.02202v1
2024-01-05,Solving convex optimization problems via a second order dynamical system with implicit Hessian damping and Tikhonov regularization,"This paper deals with a second order dynamical system with a Tikhonov
regularization term in connection to the minimization problem of a convex
Fr\'echet differentiable function. The fact that beside the asymptotically
vanishing damping we also consider an implicit Hessian driven damping in the
dynamical system under study allows us, via straightforward explicit
discretization, to obtain inertial algorithms of gradient type. We show that
the value of the objective function in a generated trajectory converges rapidly
to the global minimum of the objective function and depending the Tikhonov
regularization parameter the generated trajectory converges weakly to a
minimizer of the objective function or the generated trajectory converges
strongly to the element of minimal norm from the $\argmin$ set of the objective
function. We also obtain the fast convergence of the velocities towards zero
and some integral estimates. Our analysis reveals that the Tikhonov
regularization parameter and the damping parameters are strongly correlated,
there is a setting of the parameters that separates the cases when weak
convergence of the trajectories to a minimizer and strong convergence of the
trajectories to the minimal norm minimizer can be obtained.",2401.02676v1
2024-01-16,"Influence of temperature, doping, and amorphization on the electronic structure and magnetic damping of iron","Hybrid magnonic quantum systems have drawn increased attention in recent
years for coherent quantum information processing, but too large magnetic
damping is a persistent concern when metallic magnets are used. Their intrinsic
damping is largely determined by electron-magnon scattering induced by
spin-orbit interactions. In the low scattering limit, damping is dominated by
intra-band electronic transitions, which has been theoretically shown to be
proportional to the electronic density of states at the Fermi level. In this
work, we focus on body-centered-cubic iron as a paradigmatic ferromagnetic
material. We comprehensively study its electronic structure using
first-principles density functional theory simulations and account for finite
lattice temperature, boron (B) doping, and structure amorphization. Our results
indicate that temperature induced atomic disorder and amorphous atomic
geometries only have a minor influence. Instead, boron doping noticeably
decreases the density of states near the Fermi level with an optimal doping
level of 6.25%. In addition, we show that this reduction varies significantly
for different atomic geometries and report that the highest reduction
correlates with a large magnetization of the material. This may suggest
materials growth under external magnetic fields as a route to explore in
experiment.",2401.08076v1
2024-01-16,Waves in strong centrifugal filed: dissipative gas,"In the fast rotating gas (with the velocity typical for Iguassu gas
centrifuge) three families of linear waves exist with different polarizations
and law of dispersion. The energy of the waves is basically concentrated at the
axis of rotation in the rarefied region. Therefore these waves decay on the
distance comparable with the wavelength. There is only one type of waves
propagating strictly along the axis of rotation with the law of dispersion
similar to ordinary acoustic waves. These waves are interested for the physics
of gas centrifuges. The energy density of these waves concentrates at the wall
of the rotor. These waves have weak damping due to the molecular viscosity and
heat conductivity. The damping coefficient is determined for this type of waves
by numerical calculations. Analytical approximations for the damping
coefficient is defined as well. At the parameters typical for the Iguassu
centrifuge the damping is defined by interaction of the waves with the rotor
wall.",2401.08240v1
2024-01-19,Upper bound of the lifespan of the solution to the nonlinear fractional wave equations with time-dependent damping,"In this paper, we study the Cauchy problem of the nonlinear wave equation
with fractional Laplacian and time-dependent damping. Firstly, we derive the
weighted Sobolev estimate of the solution operators for the linear wave
equation with the damping of constant coefficient, and prove the local
existence and uniqueness in the weighted Sobolev space for the power-type
nonlinearity and $b(t)\in L^\infty$, by the contraction mapping principle.
Secondly, we consider the case of the source nonlinearity $f(u)\approx |u|^p$.
In the subcritical and critical cases $1<p\leq p_c=1+\frac \sigma N$, based on
the blow-up result on the ordinary differential inequality, we could prove the
blow-up of the solution and obtain the upper bound of the lifespan. And the
upper bound of the lifespan in the critical case is independent on the
coefficient of the time-dependent damping and is completely new even if the
classical case $b(t)=1$.",2401.10552v1
2024-03-13,Effects of wave damping and finite perpendicular scale on three-dimensional Alfvén wave parametric decay in low-beta plasmas,"Shear Alfven wave parametric decay instability (PDI) provides a potential
path toward significant wave dissipation and plasma heating. However,
fundamental questions regarding how PDI is excited in a realistic
three-dimensional (3D) open system and how critically the finite perpendicular
wave scale -- as found in both the laboratory and space plasmas -- affects the
excitation remain poorly understood. Here, we present the first 3D,
open-boundary, hybrid kinetic-fluid simulations of kinetic Alfven wave PDI in
low-beta plasmas. Key findings are that the PDI excitation is strongly limited
by the wave damping present, including electron-ion collisional damping
(represented by a constant resistivity) and geometrical attenuation associated
with the finite-scale Alfven wave, and ion Landau damping of the child acoustic
wave. The perpendicular wave scale alone, however, plays no discernible role,
with different wave scales exhibiting similar instability growth. These
findings are corroborated by theoretical analysis and estimates. The new
understanding of 3D kinetic Alfven wave PDI physics is essential for laboratory
study of the basic plasma process and may also help evaluate the relevance/role
of PDI in low-beta space plasmas.",2403.08179v1
2024-03-19,Polarization Dynamics in Paramagnet of Charged Quark-Gluon Plasma,"It is commonly understood that the strong magnetic field produced in heavy
ion collisions is short-lived. The electric conductivity of the quark-gluon
plasma is unable to significantly extend the life time of magnetic field. We
propose an alternative scenario to achieve this: with finite baryon density and
spin polarization by the initial magnetic field, the quark-gluon plasma behaves
as a paramagnet, which may continue to polarize quark after fading of initial
magnetic field. We confirm this picture by calculations in both quantum
electrodynamics and quantum chromodynamics. In the former case, we find a
splitting in the damping rates of probe fermion with opposite spin component
along the magnetic field with the splitting parametrically small than the
average damping rate. In the latter case, we find a similar splitting in the
damping rates of probe quark with opposite spin components along the magnetic
field. The splitting is parametrically comparable to the average damping rate,
providing an efficient way of polarizing strange quarks by the quark-gluon
plasma paramagnet consisting of light quarks.",2403.12615v1
2024-03-25,Radiation damping of a Rayleigh scatterer illuminated by a plane wave,"We investigate the radiation damping experienced by a dielectric spherical
particle when it is illuminated by an electromagnetic plane wave within the
Rayleigh regime. We derive the equivalent electric dipole of the moving
particle and subsequently calculate the electromagnetic force acting on it from
two different approaches. In the first approach, we calculate the force from
the integration of stress tensor and field momentum. In the second one, we
calculate the force directly from the integration of the force density. Our
derivations reveal that the damping coefficient is equal to $6P_{scat}/mc^2$
along the propagation direction, whereas it is $P_{scat}/mc^2$ along
perpendicular directions. Here, $P_{scat}$ denotes the power scattered by the
particle, and $mc^2$ represents the particle's mass energy. The radiation
damping derived in this study sets upper limits on the quality factor of
optically levitated objects and ensures the existence of a steady-state
solution of the particle's dynamics.",2403.16618v1
2006-04-14,The UCSD Radio-Selected Quasar Survey for Damped Lyman alpha System,"As large optical quasar surveys for damped Lya become a reality and the study
of star forming gas in the early Universe achieves statistical robustness, it
is now vital to identify and quantify the sources of systematic error. Because
the nature of optically-selected quasar surveys makes them vulnerable to dust
obscuration, we have undertaken a radio-selected quasar survey for damped Lya
systems to address this bias. We present the definition and results of this
survey. We then combine our sample with the CORALS dataset to investigate the
HI column density distribution function f(N) of damped Lya systems toward
radio-selected quasars. We find that f(N) is well fit by a power-law f(N) = k_1
N^alpha_1, with log k_1 = 22.90 and alpha_1 = -2.18. This power-law is in
excellent agreement with that of optically-selected samples at low N(HI), an
important yet expected result given that obscuration should have negligible
effect at these gas columns. However, because of the relatively small size of
the radio-selected sample, 26 damped Lya systems in 119 quasars, f(N) is not
well constrained at large N(HI) and the first moment of the HI distribution
function, Omega_g, is, strictly speaking, a lower limit. The power-law is steep
enough, however, that extrapolating it to higher column densities implies only
a modest, logarithmic increase in Omega_g. The radio-selected value of Omega_g
= 1.15 x 10^-3, agrees well with the results of optically-selected surveys.
While our results indicate that dust obscuration is likely not a major issue
for surveys of damped Lya systems, we estimate that a radio-selected sample of
approximately 100 damped Lya systems will be required to obtain the precision
necessary to absolutely confirm an absence of dust bias.",0604334v1
2013-05-31,Highly inclined and eccentric massive planets I: Planet-disc interactions,"In the Solar System, planets have a small inclination with respect to the
equatorial plane of the Sun, but there is evidence that in extrasolar systems
the inclination can be very high. This spin-orbit misalignment is unexpected,
as planets form in a protoplanetary disc supposedly aligned with the stellar
spin. Planet-planet interactions are supposed to lead to a mutual inclination,
but the effects of the protoplanetary disc are still unknown. We investigate
therefore planet-disc interactions for planets above 1M_Jup. We check the
influence of the inclination i, eccentricity e, and mass M_p of the planet. We
perform 3D numerical simulations of protoplanetary discs with embedded
high-mass planets. We provide damping formulae for i and e as a function of i,
e, and M_p that fit the numerical data. For highly inclined massive planets,
the gap opening is reduced, and the damping of i occurs on time-scales of the
order of 10^-4 deg/yr M_disc/(0.01 M_star) with the damping of e on a smaller
time-scale. While the inclination of low planetary masses (<5M_Jup) is always
damped, large planetary masses with large i can undergo a Kozai-cycle with the
disc. These Kozai-cycles are damped in time. Eccentricity is generally damped,
except for very massive planets (M_p = 5M_Jup) where eccentricity can increase
for low inclinations. The dynamics tends to a final state: planets end up in
midplane and can then, over time, increase their eccentricity as a result of
interactions with the disc. The interactions with the disc lead to damping of i
and e after a scattering event of high-mass planets. If i is sufficiently
reduced, the eccentricity can be pumped up because of interactions with the
disc. If the planet is scattered to high inclination, it can undergo a
Kozai-cycle with the disc that makes it hard to predict the exact movement of
the planet and its orbital parameters at the dispersal of the disc.",1305.7330v1
2014-10-20,Frequency-dependent attenuation and elasticity in unconsolidated earth materials: effect of damping,"We use the Discrete Element Method (DEM) to understand the underlying
attenuation mechanism in granular media, with special applicability to the
measurements of the so-called effective mass developed earlier. We consider
that the particles interact via Hertz-Mindlin elastic contact forces and that
the damping is describable as a force proportional to the velocity difference
of contacting grains. We determine the behavior of the complex-valued normal
mode frequencies using 1) DEM, 2) direct diagonalization of the relevant
matrix, and 3) a numerical search for the zeros of the relevant determinant.
All three methods are in strong agreement with each other. The real and the
imaginary parts of each normal mode frequency characterize the elastic and the
dissipative properties, respectively, of the granular medium. We demonstrate
that, as the interparticle damping, $\xi$, increases, the normal modes exhibit
nearly circular trajectories in the complex frequency plane and that for a
given value of $\xi$ they all lie on or near a circle of radius $R$ centered on
the point $-iR$ in the complex plane, where $R\propto 1/\xi$. We show that each
normal mode becomes critically damped at a value of the damping parameter $\xi
\approx 1/\omega_n^0$, where $\omega_n^0$ is the (real-valued) frequency when
there is no damping. The strong indication is that these conclusions carry over
to the properties of real granular media whose dissipation is dominated by the
relative motion of contacting grains. For example, compressional or shear waves
in unconsolidated dry sediments can be expected to become overdamped beyond a
critical frequency, depending upon the strength of the intergranular damping
constant.",1410.5484v2
2012-04-12,Evidence of Gunn-Peterson damping wings in high-z quasar spectra: strengthening the case for incomplete reionization,"The spectra of several high-redshift (z>6) quasars have shown evidence for a
Gunn-Peterson (GP) damping wing, indicating a substantial mean neutral hydrogen
fraction (x_HI > 0.03) in the z ~ 6 intergalactic medium (IGM). However,
previous analyses assumed that the IGM was uniformly ionized outside of the
quasar's HII region. Here we relax this assumption and model patchy
reionization scenarios for a range of IGM and quasar parameters. We quantify
the impact of these differences on the inferred x_HI, by fitting the spectra of
three quasars: SDSS J1148+5251 (z=6.419), J1030+0524 (z=6.308), and J1623+3112
(z=6.247). We find that the best-fit values of x_HI in the patchy models agree
well with the uniform case. More importantly, we confirm that the observed
spectra favor the presence of a GP damping wing, with peak likelihoods
decreasing by factors of > few - 10 when the spectra are modeled without a
damping wing. We also find that the Ly alpha absorption spectra, by themselves,
cannot distinguish the damping wing in a relatively neutral IGM from a damping
wing in a highly ionized IGM, caused either by an isolated neutral patch, or by
a damped Ly alpha absorber (DLA). However, neutral patches in a highly ionized
universe (x_HI < 0.01), and DLAs with the large required column densities (N_HI
> few x 10^{20} cm^{-2}) are both rare. As a result, when we include reasonable
prior probabilities for the line of sight (LOS) to intercept either a neutral
patch or a DLA at the required distance of ~ 40-60 comoving Mpc away from the
quasar, we find strong lower limits on the neutral fraction in the IGM, x_HI >
0.1 (at 95% confidence). This strengthens earlier claims that a substantial
global fraction of hydrogen in the z~6 IGM is in neutral form.",1204.2838v2
2020-08-05,Fast optimization via inertial dynamics with closed-loop damping,"In a Hilbert space $H$, in order to develop fast optimization methods, we
analyze the asymptotic behavior, as time $t$ tends to infinity, of inertial
continuous dynamics where the damping acts as a closed-loop control. The
function $f: H \to R$ to be minimized (not necessarily convex) enters the
dynamic through it gradient, which is assumed to be Lipschitz continuous on the
bounded subsets of $H$. This gives autonomous dynamical systems with nonlinear
damping and nonlinear driving force. We first consider the case where the
damping term $\partial \phi (\dot{x}(t))$ acts as a closed-loop control of the
velocity. The damping potential $\phi : H \to [0,+\infty)$ is a convex
continuous function which achieves its minimum at the origin. We show the
existence and uniqueness of a global solution to the associated Cauchy problem.
Then, we analyze the asymptotic convergence properties of the generated
trajectories generated. We use techniques from optimization, control theory,
and PDE's: Lyapunov analysis based on the decreasing property of an energy-like
function, quasi-gradient and Kurdyka-Lojasiewicz theory, monotone operator
theory for wave-like equations. Convergence rates are obtained based on the
geometric properties of the data $f$ and $\phi$. When $f$ is strongly convex,
we give general conditions which provide exponential convergence rates. Then,
we extend the results to the case where an additional Hessian-driven damping
enters the dynamic, which reduces the oscillations. Finally, we consider an
inertial system involving jointly the velocity $\dot{x}(t)$ and the gradient
$\nabla f(x(t))$. In addition to its original results, this work surveys the
numerous works devoted in recent years to the interaction between continuous
damped inertial dynamics and numerical algorithms for optimization, with the
emphasis on autonomous systems, closed-loop adaptive procedures, and
convergence rates.",2008.02261v3
2023-01-10,Cosmic Ray Drag and Damping of Compressive Turbulence,"While it is well-known that cosmic rays (CRs) can gain energy from turbulence
via second order Fermi acceleration, how this energy transfer affects the
turbulent cascade remains largely unexplored. Here, we show that damping and
steepening of the compressive turbulent power spectrum are expected once the
damping time $t_{\rm damp} \sim \rho v^{2}/\dot{E}_{\rm CR} \propto E_{\rm
CR}^{-1}$ becomes comparable to the turbulent cascade time. Magnetohydrodynamic
(MHD) simulations of stirred compressive turbulence in a gas-CR fluid with
diffusive CR transport show clear imprints of CR-induced damping, saturating at
$\dot{E}_{\rm CR} \sim \tilde{\epsilon}$, where $\tilde{\epsilon}$ is the
turbulent energy input rate. In that case, almost all the energy in large scale
motions is absorbed by CRs and does not cascade down to grid scale. Through a
Hodge-Helmholtz decomposition, we confirm that purely compressive forcing can
generate significant solenoidal motions, and we find preferential CR damping of
the compressive component in simulations with diffusion and streaming,
rendering small-scale turbulence largely solenoidal, with implications for
thermal instability and proposed resonant scattering of $E > 300$ GeV CRs by
fast modes. When CR transport is streaming dominated, CRs also damp large scale
motions, with kinetic energy reduced by up to to an order of magnitude in
realistic $E_{\rm CR} \sim E_{\rm g}$ scenarios, but turbulence (with a reduced
amplitude) still cascades down to small scales with the same power spectrum.
Such large scale damping implies that turbulent velocities obtained from the
observed velocity dispersion may significantly underestimate turbulent forcing
rates, i.e. $\tilde{\epsilon} \gg \rho v^{3}/L$.",2301.04156v2
2024-02-12,"Relaxation of weakly collisional plasma: continuous spectra, Landau eigenmodes, and transition from the collisionless to the fluid limit","The relaxation of a weakly collisional plasma is described by the
Boltzmann-Poisson equations with the Lenard-Bernstein collision operator. We
perform a perturbative analysis of these equations, and obtain, for the first
time, exact analytic solutions, enabling definitive resolutions to
long-standing controversies regarding the impact of weak collisions on
continuous spectra and Landau eigenmodes. Unlike some previous studies, we
retain both damping and diffusion terms in the collision operator. We find that
the linear response is a temporal convolution of a continuum that depends on
the continuous velocities of particles, and discrete normal modes that
encapsulate coherent oscillations. The normal modes are exponentially damped
over time due to collective effects (Landau damping) as well as collisional
dissipation. The continuum is also damped by collisions but somewhat
differently. Up to a collision time, which is the inverse of the collision
frequency $\nu_{\mathrm{c}}$, the continuum decay is driven by velocity
diffusion and occurs super-exponentially over a timescale $\sim
\nu^{-1/3}_{\mathrm{c}}$. After a collision time, however, the continuum decay
is driven by the collisional damping of particle velocities and diffusion of
their positions, and occurs exponentially over a timescale $\sim
\nu_{\mathrm{c}}$. This hitherto unknown, slow exponential decay causes
perturbations to damp the most on scales comparable to the mean free path, but
very slowly on larger scales, which establishes the local thermal equilibrium,
the essence of the fluid limit. The long-term decay of the response is driven
by the normal modes on scales smaller than the mean free path, but, on larger
scales, is governed by the slowly decaying continuum and the least damped
normal mode. Our analysis firmly establishes a long-sought connection between
the collisionless and fluid limits of weakly collisional plasmas.",2402.07992v1
2000-09-10,A New Connection between Central Engine Weak Physics and the Dynamics of Gamma-Ray Burst Fireballs,"We demonstrate a qualitatively new aspect of the dynamics of Gamma-Ray Burst
(GRB) fireballs: the development of a substantial dispersion in the proton
component in fireballs in which neutron decoupling occurs and is sufficiently
pronounced. This effect depends sensitively on the neutron to proton ratio in
the fireball, becoming more dramatic with increasing neutron excess. Simple
physical arguments and transport calculations indicate that the dispersion in
Lorentz factor of the protons can be of order the final mean Lorentz factor of
the fireball. We show how plasma instabilities could play an important role in
the evolution of the fireball and how they might ultimately govern the
development of such a velocity dispersion in the proton component. The role of
these instabilities in setting/diminishing a proton Lorentz factor dispersion
represents a new and potentially important venue for the study of plasma
instabilities. Significant dispersion in the proton velocities translates into
fewer protons attaining the highest Lorentz factors. This is tantamount to a
reduction in the total energy required to attain a given Lorentz factor for the
highest energy protons. As well, a proton component dispersion can have
consequences for the electromagnetic and neutrino signature of GRBs.",0009144v3
2002-12-09,Lorentz violation and Crab synchrotron emission: a new constraint far beyond the Planck scale,"Special relativity asserts that physical phenomena appear the same for all
inertially moving observers. This symmetry, called Lorentz symmetry, relates
long wavelengths to short ones: if the symmetry is exact it implies that
spacetime must look the same at all length scales. Several approaches to
quantum gravity, however, suggest that there may be a Lorentz violating
microscopic structure of spacetime, for example discreteness,
non-commutativity, or extra dimensions. Here we determine a very strong
constraint on a type of Lorentz violation that produces a maximum electron
speed less than the speed of light. We use the observation of 100 MeV
synchrotron radiation from the Crab nebula to improve the previous limits by a
factor of 40 million, ruling out this type of Lorentz violation, and thereby
providing an important constraint on theories of quantum gravity.",0212190v2
2005-11-21,The bulk Lorentz factor crisis of TeV blazars : evidence for an inhomogeneous pileup energy distribution ?,"There is growing evidence that the estimations of the beaming Doppler factor
in TeV BL Lac object based on the Self Synchrotron Compton (SSC) models are in
strong disagreement with those deduced from the unification models between
blazars and radio galaxies. When corrected from extragalactic absorption by the
diffuse infrared background (DIrB), the SSC one-zone models require very high
Lorentz factor (around 50) to avoid strong gamma-gamma absorption. However, the
statistics on beamed vs. unbeamed objects, as well as the luminosity contrast,
favors much lower Lorentz factor of the order of 3. In this paper, we show that
for the special case of Markarian 501, the need for very high Lorentz factor is
unavoidable for all one-zone models where all photons are assumed to be
produced at the same location at the same time. Models assuming a double
structure with two different beaming patterns can partially solve the problem
of luminosity contrast, but we point out that they are inconsistent with the
statistics on the number of detected TeV sources. The only way to solve the
issue is to consider inhomogeneous models, where low energy and high energy
photons are not produced at the same place, allowing for much smaller Lorentz
factors. It implies that the jet is stratified, but also that the particle
energy distribution is close to a monoenergetic one, and that pair production
is likely to be significant. The implications on relativistic jet physics and
particle acceleration mechanism are discussed.",0511610v1
2006-12-12,The Lorentz force in atmospheres of CP stars: $θ$ Aurigae,"Several dynamical processes may induce considerable electric currents in the
atmospheres of magnetic chemically peculiar (CP) stars. The Lorentz force,
which results from the interaction between the magnetic field and the induced
currents, modifies the atmospheric structure and induces characteristic
rotational variability of the hydrogen Balmer lines. To study this phenomena we
have initiated a systematic spectroscopic survey of the Balmer lines variation
in magnetic CP stars. In this paper we continue presentation of results of the
program focusing on the high-resolution spectral observations of A0p star \aur
(HD 40312). We have detected a significant variability of the H$\alpha$,
H$\beta$, and H$\gamma$ spectral lines during full rotation cycle of the star.
This variability is interpreted in the framework of the model atmosphere
analysis, which accounts for the Lorentz force effects. Both the inward and
outward directed Lorentz forces are considered under the assumption of the
axisymmetric dipole or dipole+quadrupole magnetic field configurations. We
demonstrate that only the model with the outward directed Lorentz force in the
dipole+quadrupole configuration is able to reproduce the observed hydrogen line
variation. These results present new strong evidences for the presence of
non-zero global electric currents in the atmosphere of an early-type magnetic
star.",0612301v1
2006-03-17,Unusual High-Energy Phenomenology of Lorentz-Invariant Noncommutative Field Theories,"It has been suggested that one may construct a Lorentz-invariant
noncommutative field theory by extending the coordinate algebra to additional,
fictitious coordinates that transform nontrivially under the Lorentz group.
Integration over these coordinates in the action produces a four-dimensional
effective theory with Lorentz invariance intact. Previous applications of this
approach, in particular to a specific construction of noncommutative QED, have
been studied only in a low-momentum approximation. Here we discuss
Lorentz-invariant field theories in which the relevant physics can be studied
without requiring an expansion in the inverse scale of noncommutativity.
Qualitatively, we find that tree-level scattering cross sections are
dramatically suppressed as the center-of-mass energy exceeds the scale of
noncommutativity, that cross sections that are isotropic in the commutative
limit can develop a pronounced angular dependence, and that nonrelativistic
potentials (for example, the Coloumb potential) become nonsingular at the
origin. We consider a number of processes in noncommutative QED that may be
studied at a future linear collider. We also give an example of scattering via
a four-fermion operator in which the noncommutative modifications of the
interaction can unitarize the tree-level amplitude, without requiring any other
new physics in the ultraviolet.",0603137v3
2000-07-24,Quantum mechanics with non-unitary symmetries,"This article shows that one can consistently incorporate nonunitary
representations of at least one group into the ``ordinary'' nonrelativistic
quantum mechanics. This group turns out to be Lorentz group thus giving us an
alternative approach to QFT for combining the quantum mechanics and special
theory of relativity which keeps the concept of wave function (belonging to
some representation of Lorentz group) through the whole theory. Scalar product
has been redefined to take into the account the nonunitarity of representations
of Lorentz group. Understanding parity symmetry turns out to be the key
ingredient throughout the process. Instead of trying to guess an equation or a
set of equations for some wave functions or fields (or equivalently trying to
guess a Lagrangian for the same), one derives them based only on the
superposition principle and properties of wave functions under Lorentz
transformations and parity. The resulting model has striking similarities with
the standard quantum field theory and yet has no negative energy states, no
zitterbewegung effects, symmetric energy momentum tensor and angular momentum
density tensor for \emph{all} representations of Lorentz group (unifying the
theoretical description of all particles), as well as clear physical
interpretation. It also offers a possible interpretation why particles and
antiparticles have opposite quantum numbers.",0007193v3
2002-12-16,Lorentz-Invariant Non-Commutative Space-Time Based On DFR Algebra,"It is argued that the familiar algebra of the non-commutative space-time with
$c$-number $\theta^{\mu\nu}$ is inconsistent from a theoretical point of view.
Consistent algebras are obtained by promoting $\theta^{\mu\nu}$ to an
anti-symmetric tensor operator ${\hat\theta}^{\mu\nu}$. The simplest among them
is Doplicher-Fredenhagen-Roberts (DFR) algebra in which the triple commutator
among the coordinate operators is assumed to vanish. This allows us to define
the Lorentz-covariant operator fields on the DFR algebra as operators diagonal
in the 6-dimensional $\theta$-space of the hermitian operators,
${\hat\theta}^{\mu\nu}$. It is shown that we then recover Carlson-Carone-Zobin
(CCZ) formulation of the Lorentz-invariant non-commutative gauge theory with no
need of compactification of the extra 6 dimensions. It is also pointed out that
a general argument concerning the normalizability of the weight function in the
Lorentz metric leads to a division of the $\theta$-space into two disjoint
spaces not connected by any Lorentz transformation so that the CCZ covariant
moment formula holds true in each space, separately. A non-commutative
generalization of Connes' two-sheeted Minkowski space-time is also proposed.
Two simple models of quantum field theory are reformulated on $M_4\times Z_2$
obtained in the commutative limit.",0212176v1
2006-10-16,Deriving Gauge Symmetry and Spontaneous Lorentz Violation,"We consider a class of field theories with a four-vector field $A_{\mu}(x)$
in addition to other fields supplied with a global charge symmetry - theories
which have partial gauge symmetry in the sense of only imposing it on those
terms in the Lagrangian density which have derivatives as factors in them. We
suppose that spontaneous Lorentz invariance breaking occurs in such a theory
due to the four-vector field taking a non-zero vacuum expectation value. Under
some very mild assumptions, we show that this Lorentz violation is not
observable and the whole theory is practically gauge invariant. A very
important presupposition for this theorem is that an initial condition is
imposed on the no-derivative expressions corresponding to the early Universe
being essentially in a vacuum state. This condition then remains true forever
and can be interpreted as a gauge constraint. We formulate the conditions under
which the spontaneous Lorentz violation becomes observable. Spontaneously
broken Lorentz invariance could be seen by some primordially existing or
created ""fossil"" charges with the property of moving through the Universe with
a fixed velocity.",0610186v2
2006-08-31,Relativity grupoid insted of relativity group,"Minkowski in 1908 used space-like binary velocity-field of a medium, relative
to an observer. Hestenes in 1974 introduced, within a Clifford algebra, an
axiomatic binary relative velocity as a Minkowski bivector. We propose consider
binary relative velocity as a traceless nilpotent endomorphism in an operator
algebra. Any concept of a binary axiomatic relative velocity made possible the
replacement of the Lorentz relativity group by the relativity groupoid. The
relativity groupoid is a category of massive bodies in mutual relative motions,
where a binary relative velocity is interpreted as a categorical morphism with
the associative addition. This associative addition is to be contrasted with
non-associative addition of (ternary) relative velocities in isometric special
relativity (loop structure).
  We consider an algebra of many time-plus-space splits, as an operator algebra
generated by idempotents. The kinematics of relativity groupoid is ruled by
associative Frobenius operator algebra, whereas the dynamics of categorical
relativity needs the non-associative Fr\""olicher-Richardson operator algebra.
  The Lorentz covariance is the cornerstone of physical theory.
Observer-dependence within relativity groupoid, and the Lorentz-covariance
(within the Lorentz relativity group), are different concepts. Laws of Physics
could be observer-free, rather than Lorentz-invariant.",0608770v2
2003-08-28,Hyperspherical Functions and Harmonic Analysis on the Lorentz Group,"Matrix elements of spinor and principal series representations of the Lorentz
group are studied in the basis of complex angular momentum (helicity basis). It
is shown that matrix elements are expressed via hyperspherical functions
(relativistic spherical functions). In essence, the hyperspherical functions
present itself a four-dimensional (with respect to a pseudo-euclidean metrics
of Minkowski spacetime) generalization of the usual three-dimensional spherical
functions. An explicit form of the hyperspherical functions is given. The
hypespherical functions of the spinor representations are represented by a
product of generalized spherical functions and Jacobi functions. It is shown
that zonal hyperspherical functions are expressed via the Appell functions. The
associated hyperspherical functions are defined as the functions on a
two-dimensional complex sphere. Integral representations, addition theorems,
symmetry and recurrence relations for hyperspherical functions are given. In
case of the principal and supplementary series representations of the Lorentz
group, the matrix elements are expressed via the functions represented by a
product of spherical and conical functions. The hyperspherical functions of the
principal series representations allow one to apply methods of harmonic
analysis on the Lorentz group. Different forms of expansions of square
integrable functions on the Lorentz group are studied. By way of example, an
expansion of the wave function, representing the Dirac field
$(1/2,0)\oplus(0,1/2)$, is given.",0308039v2
2003-04-13,"Einstein, Wigner, and Feynman: From E = mc^{2} to Feynman's decoherence via Wigner's little groups","The 20th-century physics starts with Einstein and ends with Feynman. Einstein
introduced the Lorentz-covariant world with E = mc^{2}. Feynman observed that
fast-moving hadrons consist of partons which act incoherently with external
signals. If quarks and partons are the same entities observed in different
Lorentz frames, the question then is why partons are incoherent while quarks
are coherent. This is the most puzzling question Feynman left for us to solve.
In this report, we discuss Wigner's role in settling this question. Einstein's
E = mc^{2}, which takes the form E = \sqrt{m^{2} + p^{2}}, unifies the
energy-momentum relations for massive and massless particles, but it does not
take into account internal space-time structure of relativistic particles. It
is pointed out Wigner's 1939 paper on the inhomogeneous Lorentz group defines
particle spin and gauge degrees of freedom in the Lorentz-covariant world.
Within the Wigner framework, it is shown possible to construct the internal
space-time structure for hadrons in the quark model. It is then shown that the
quark model and the parton model are two different manifestations of the same
covariant entity. It is shown therefore that the lack of coherence in Feynman's
parton picture is an effect of the Lorentz covariance.",0304097v2
2009-03-17,An implicit advection scheme for modeling relativistic shocks with high Lorentz factors,"Jet-plasmas emanating from the vicinity of relativistic objects and in
gamma-ray bursts have been observed to propagate with Lorentz factors laying in
the range between one and several hundreds. On the other hand, the numerical
studies of such flows have been focussed so far mainly on the lowest possible
range of Lorentz factors $\Gamma,$ specifically, on the regime $1\leq \Gamma
\leq 5.$ Therefore, relativistic flows with high $\Gamma-$factors have poorly
studied, as most numerical methods are found to encounter severe numerical
difficulties or even become numerically unstable for $\Gamma \gg 1. In this
paper we present an implicit numerical advection scheme for modeling the
propagation of relativistic plasmas with shocks, discuss its consistency with
respect to both the internal and total energy formulation in general
relativity. Using the total energy formulation, the scheme is found to be
viable for modeling moving shocks with moderate Lorentz factors, though with
relatively small Courant numbers. In the limit of high Lorentz factors, the
internal energy formulation in combination with a fine-tuned artificial
viscosity is much more robust and efficient. We confirm our conclusions by
performing test calculations and compare the results with analytical solutions
of the relativistic shock tube problem. The aim of the present modification is
to enhance the robustness of the general relativistic implicit radiative MHD
solver: GR-I-RMHD
(http://www1.iwr.uni-heidelberg.de/groups/compastro/home/gr-i-mhd-solver) and
extend its range of applications into the high $\Gamma-$regime.}",0903.3025v2
2009-04-24,Modified Gravitational Equations on Braneworld with Lorentz Invariant Violation,"The modified gravitational equations to describe a four-dimensional
braneworld in the case with the Lorentz invariant violation in a bulk spacetime
is presented. It contains a trace part of the brane energy-momentum tensor and
the coefficients of all terms describe the Lorentz violation effects from the
bulk spacetime. As an application, we apply this formalism to study cosmology.
In respect to standard effective Friedmann equations on the brane, Lorentz
invariance violation in the bulk causes a modification of this equations that
can lead to significant physical consequences. In particular, the effective
Friedmann equation on the brane explicitly depends on the equation of state of
the brane matter and the Lorentz violating parameters. We show that the
components of five-dimensional Weyl curvature are related to the matter on
brane even at low energies. We also find that the constraints on the theory
parameters are depend on the equation of state of the energy components of the
brane matter. Finally, the stability of the model depend on the specific
choices of initial conditions and the parameters $\beta_i$.",0904.3899v2
2009-08-31,Early afterglows from radially structured outflows and the application to X-ray shallow decays,"In the fireball model, it is more physically realistic that gamma-ray burst
(GRB) ejecta have a range of bulk Lorentz factors (assuming $M\propto
\Gamma^{-s}$). The low Lorentz factor part of the ejecta will catch up with the
high Lorentz factor part when the latter is decelerated by the surrounding
medium to a comparable Lorentz factor. Such a process will develop a
long-lasting weak reverse shock until the whole ejecta are shocked. Meanwhile,
the forward shocked materials are gradually supplied with energy from the
ejecta that are catching-up, and thus the temporal decay of the forward shock
emission will be slower than that without an energy supply. However, the
reverse shock may be strong. Here, we extend the standard reverse-forward shock
model to the case of radially nonuniform ejecta. We show that this process can
be classified into two cases: the thick shell case and the thin shell case. In
the thin shell case, the reverse shock is weak and the temporal scaling law of
the afterglow is the same as that in Sari & Mesz (2000). However, in the thick
shell case, the reverse shock is strong and thus its emission dominates the
afterglow in the high energy band. Our results also show slower decaying
behavior of the afterglow due to the energy supply by low Lorentz factor
materials, which may help the understanding of the plateau observed in the
early optical and X-ray afterglows.",0908.4511v1
2010-06-10,Moving Charge Distributions in Classical Electromagnetism and the FitzGerald-Lorentz Contraction,"In [Eur. J. Phys. {\bf 25} (2004) 123-126], Dragan V. Red{\v z}i\'c is led to
the FitzGerald-Lorentz contraction by comparing electromagnetic images of a
moving point charge and a moving conducting sphere. We wish to point out that
much simpler possibilities intrinsic to electromagnetism already exist from
which we may get at the FitzGerald-Lorentz contraction hypothesis. In
particular we consider an example going back to Poincar\'e in [{\it Bulletin
des Sciences math\'ematiques}, 28, (1904) pp. 302-324], in which he considers
the problem of two moving, parallel line charges in order to get at length
contraction. We develop this model of Poincar\'e and show that it leads not
only to the FitzGerald-Lorentz contraction but also to an elementary derivation
of the composition of velocities formula in special relativity for collinear
velocities.
  Red{\v z}i\'c suggests that, by considering such purely electromagnetic
examples, the Maxwellians could have been led to the contraction hypothesis
much before the time of the Michelson-Morely experiment, and we agree with him
that such elementary results as the ones discussed here could not have escaped
their attention. Apparently, it took an extremely sensitive experiment, not
intrinsic to electromagnetism, such as was the Michelson-Morley experiment,
together with the efforts of persons with authority, like Lorentz and
Poincar\'e, trying to uphold the relativity principle before the radical notion
of length contraction could seriously be entertained, and making ripe the way
for the genius of Einstein.",1006.2029v1
2011-05-03,Quantum scalar field in quantum gravity: the propagator and Lorentz invariance in the spherically symmetric case,"We recently studied gravity coupled to a scalar field in spherical symmetry
using loop quantum gravity techniques. Since there are local degrees of freedom
one faces the ""problem of dynamics"". We attack it using the ""uniform
discretization technique"". We find the quantum state that minimizes the value
of the master constraint for the case of weak fields and curvatures. The state
has the form of a direct product of Gaussians for the gravitational variables
times a modified Fock state for the scalar field. In this paper we do three
things. First, we verify that the previous state also yields a small value of
the master constraint when one polymerizes the scalar field in addition to the
gravitational variables. We then study the propagators for the polymerized
scalar field in flat space-time using the previously considered ground state in
the low energy limit. We discuss the issue of the Lorentz invariance of the
whole approach. We note that if one uses real clocks to describe the system,
Lorentz invariance violations are small. We discuss the implications of these
results in the light of Horava's Gravity at the Lifshitz point and of the
argument about potential large Lorentz violations in interacting field theories
of Collins et. al.",1105.0667v2
2011-08-31,Aspects of a planar nonbirefringent and CPT-even electrodynamics stemming from the Standard Model Extension,"We have studied a (1+2)-dimensional Lorentz-violating model which is obtained
from the dimensional reduction of the nonbirefringent sector of the CPT-even
electrodynamics of the standard model extension (SME). The planar theory
contains a gauge sector and a scalar sector which are linearly coupled by means
of a Lorentz-invariance violating (LIV) vector, $S^{\mu}$, while the kinetic
terms of both sectors are affected by the components of a Lorentz-violating
symmetric tensor, $\kappa^{\mu\nu}$. The energy-momentum tensor reveals that
both sectors present energy stability for sufficiently small values of the
Lorentz-violating parameters. The full dispersion relation equations are
exactly determined and analyzed for some special configurations of the LIV
backgrounds, showing that the planar model is entirely nonbirefringent at any
order in the LIV parameters. At first order, the gauge and scalar sectors are
described by the same dispersion relations. Finally, the equations of motion
have been solved in the stationary regime and at first order in the LIV
parameters. It is observed that the Lorentz-violating parameters do not alter
the asymptotical behavior of the electric and magnetic fields but induce an
angular dependence which is not present in Maxwell's planar theory.",1108.6193v1
2011-09-13,Uncharged compactlike and fractional Lorentz-violating BPS vortices in the CPT-even sector of the standard model extension,"We have investigated and verified the existence of stable uncharged
Bogomol'nyi-Prasad-Sommerfeld (BPS) vortices in the framework of an Abelian
Maxwell-Higgs model supplemented with CPT-even and Lorentz-violating (LV) terms
belonging to the gauge and Higgs sectors of the standard model extension. The
analysis is performed in two situations: first, one by considering the Lorentz
violation only in the gauge sector and then in both gauge and Higgs sectors. In
the first case, it is observed that the model supports vortices somehow
equivalent to the ones appearing in a dielectric medium. The Lorentz violation
controls the radial extension (core of the solution) and the magnetic field
amplitude of the Abrikosov-Nielsen-Olesen vortices, yielding compactlike
defects in an alternative and simpler way than that of $k-$field models. At the
end, we consider the Lorentz-violating terms in the gauge and Higgs sectors. It
is shown that the full model also supports compactlike uncharged BPS vortices
in a modified vacuum, but this time there are two LV parameters controlling the
defect structure. Moreover, an interesting novelty is introduced by the
LV-Higgs sector: fractional vortex solutions.",1109.2931v4
2012-02-02,Extended Lorentz code of a superluminal particle,"While the OPERA experimental scrutiny is ongoing in the community, in the
present article we construct a toy model of {\it extended Lorentz code} (ELC)
of the uniform motion, which will be a well established consistent and unique
theoretical framework to explain the apparent violations of the standard
Lorentz code (SLC), the possible manifestations of which arise in a similar way
in all particle sectors. We argue that in the ELC-framework the propagation of
the superluminal particle, which implies the modified dispersion relation,
could be consistent with causality. Furthermore, in this framework, we give a
justification of forbiddance of Vavilov-Cherenkov (VC)-radiation/or analog
processes in vacuum. To be consistent with the SN1987A and OPERA data, we
identify the neutrinos from SN1987A and the light as so-called {\it 1-th type}
particles carrying the {\it individual Lorentz motion code} with the velocity
of light $c_{1}\equiv c$ in vacuum as maximum attainable velocity for all the
1-th type particles. Thereby, we treat superluminal muon neutrinos as so-called
{\it 2-nd type} particles carrying the individual Lorentz motion code with the
velocity $c_{2}$ as maximum attainable velocity for all the 2-nd type
particles. For the muon neutrinos mean energy $E_{\nu 2}=17.5$ GeV, claimed
velocity $(v_{\nu 2}-c)/c= 2.48\times 10^{-5}$, and expected finite rest mass
$m_{0}\approx 1eV/c^{2}$, we obtain then $ c_{2}/c\approx 17.5\times 10^{9}$.",1202.0469v1
2012-06-22,Deformed Lorentz symmetry and relative locality in a curved/expanding spacetime,"The interest of part of the quantum-gravity community in the possibility of
Planck-scale-deformed Lorentz symmetry is also fueled by the opportunities for
testing the relevant scenarios with analyses, from a signal-propagation
perspective, of observations of bursts of particles from cosmological
distances. In this respect the fact that so far the implications of deformed
Lorentz symmetry have been investigated only for flat (Minkowskian) spacetimes
represents a very significant limitation, since for propagation over
cosmological distances the curvature/expansion of spacetime is evidently
tangible. We here provide a significant step toward filling this gap by
exhibiting an explicit example of Planck-scale-deformed relativistic symmetries
of a spacetime with constant rate of expansion (deSitterian). Technically we
obtain the first ever example of a relativistic theory of worldlines of
particles with 3 nontrivial relativistic invariants: a large speed scale
(""speed-of-light scale""), a large distance scale (inverse of the
""expansion-rate scale""), and a large momentum scale (""Planck scale""). We
address some of the challenges that had obstructed success for previous
attempts by exploiting the recent understanding of the connection between
deformed Lorentz symmetry and relativity of spacetime locality. We also offer a
preliminary analysis of the differences between the scenario we here propose
and the most studied scenario for broken (rather than deformed) Lorentz
symmetry in expanding spacetimes.",1206.5315v1
2012-07-12,Lorentz completion of effective string (and p-brane) action,"The formation of a confining string (or a p-brane) in a Poincare' invariant
theory breaks spontaneously this symmetry which is thereby realized
non-linearly in the effective action of these extended objects. As a
consequence the form of the action is strongly constrained. A new general
method is described to obtain in a systematic way higher order Lorentz
invariant contributions to this action. We find a simple recipe to promote a
term invariant under the stability subgroup to an expression invariant under
the whole Lorentz group. It is based on the following three steps: in the
saturation of worldsheet (or worldvolume) indices replace the Minkowski metric
with the inverse of the induced metric; in the saturation of indices of the
transverse coordinates describing the position of the extended object replace
the Euclidean metric with a certain new metric; finally replace the field
derivatives of order higher than two with a certain covariant derivative.
Lorentz invariance of the expression modified this way immediately follows. We
find in particular that the leading bulk deviation of the Nambu Goto action in
any space-time dimensions is proportional to the square of scalar curvature.",1207.2912v2
2012-08-03,Generalized Lorentz law and the force of radiation on magnetic dielectrics,"The macroscopic equations of Maxwell combined with a generalized form of the
Lorentz law are a complete and consistent set; not only are these five
equations fully compatible with the special theory of relativity, they also
conform with the conservation laws of energy, momentum, and angular momentum.
The linear momentum density associated with the electromagnetic field is
p_EM(r,t)=E(r,t)\timesH(r,t)/c^2, whether the field is in vacuum or in a
ponderable medium. [Homogeneous, linear, isotropic media are typically
specified by their electric and magnetic permeabilities epsilon_0*epsilon(w)
and mu_0*mu(w).] The electromagnetic momentum residing in a ponderable medium
is often referred to as Abraham momentum. When an electromagnetic wave enters a
medium, say, from the free space, it brings in Abraham momentum at a rate
determined by the density distribution p_EM(r,t), which spreads within the
medium with the light's group velocity. The balance of the incident, reflected,
and transmitted (electromagnetic) momenta is subsequently transferred to the
medium as mechanical force in accordance with Newton's second law. The
mechanical force of the radiation field on the medium may also be calculated by
a straightforward application of the generalized form of the Lorentz law. The
fact that these two methods of force calculation yield identical results is the
basis of our claim that the equations of electrodynamics (Maxwell + Lorentz)
comply with the momentum conservation law. When applying the Lorentz law, one
must take care to properly account for the effects of material dispersion and
absorption, discontinuities at material boundaries, and finite beam dimensions.
This paper demonstrates some of the issues involved in such calculations of the
electromagnetic force in magnetic dielectric media.",1208.0854v1
2013-03-06,Hot Electromagnetic Outflows I: Acceleration and Spectra,"The theory of cold, relativistic, magnetohydrodynamic outflows is generalized
by the inclusion of an intense radiation source. In some contexts, such the
breakout of a gamma-ray burst jet from a star, the outflow is heated to a high
temperature at a large optical depth. Eventually it becomes transparent and is
pushed to a higher Lorentz factor by a combination of the Lorentz force and
radiation pressure. We obtain its profile, both inside and outside the fast
magnetosonic critical point, when the poloidal magnetic field is radial and
monopolar. Most of the energy flux is carried by the radiation field and the
toroidal magnetic field that is wound up close to the rapidly rotating engine.
Although the entrained matter carries little energy, it couples the radiation
field to the magnetic field. Then the fast critical point is pushed inward from
infinity and, above a critical radiation intensity, the outflow is accelerated
mainly by radiation pressure. We identify a distinct observational signature of
this hybrid outflow: a hardening of the radiation spectrum above the peak of
the seed photon distribution, driven by bulk Compton scattering. The
non-thermal spectrum -- obtained by a Monte Carlo method -- is most extended
when the Lorentz force dominates the acceleration, and the seed photon beam is
wider than the Lorentz cone of the MHD fluid. This effect is a generic feature
of hot, magnetized outflows interacting with slower relativistic material. It
may explain why some GRB spectra appear to peak at photon energies above the
original Amati et al. scaling. A companion paper addresses the case of jet
breakout, where diverging magnetic flux surfaces yield strong MHD acceleration
over a wider range of Lorentz factor.",1303.1553v1
2013-07-12,Black holes in Lorentz-violating gravity theories,"Lorentz-symmetry and the notion of light cones play a central role in the
definition of horizons and the existence of black holes. Current observations
provide strong indications that astrophysical black holes do exist in Nature.
Here we explore what happens to the notion of a black hole in gravity theories
where local Lorentz symmetry is violated, and discuss the relevant
astrophysical implications. Einstein-aether theory and Horava gravity are used
as the theoretical background for addressing this question. We review earlier
results about static, spherically symmetric black holes, which demonstrate that
in Lorentz-violating theories there can be a new type of horizon and, hence, a
new notion of black hole. We also present both known and new results on slowly
rotating black holes in these theories, which provide insights on how generic
these new horizons are. Finally, we discuss the differences between black holes
in Lorentz-violating theories and in General Relativity, and assess to what
extent they can be probed with present and future observations.",1307.3359v2
2013-11-27,Constraints on Einstein-Æther theory and Horava gravity from binary pulsar observations,"Binary pulsars are ideal to test the foundations of General Relativity, such
as Lorentz symmetry, which requires that experiments produce the same results
in all free-falling (i.e.inertial) frames. We here break this symmetry in the
gravitational sector by specifying a preferred time direction, and thus a
preferred frame, at each spacetime point. We then examine the consequences of
this gravitational Lorentz symmetry breaking in the orbital evolution of binary
pulsars, focusing on the dissipative effects. We find that Lorentz symmetry
breaking modifies these effects, and thus the orbital dynamics, in two
different ways. First, it generically causes the emission of dipolar radiation,
which makes the orbital separation decrease faster than in General Relativity.
Second, the quadrupole component of the emission is also modified. The orbital
evolution depends critically on the sensitivities of the stars, which measure
how their binding energies depend on the motion relative to the preferred
frame. We calculate the sensitivities numerically and compute the predicted
orbital decay rate of binary pulsars in Lorentz-violating gravity. By testing
these predictions against observations, we place very stringent constraints on
gravitational Lorentz violation.",1311.7144v4
2013-12-11,The Force Law of Classical Electrodynamics: Lorentz versus Einstein and Laub,"The classical theory of electrodynamics is built upon Maxwell's equations and
the concepts of electromagnetic field, force, energy, and momentum, which are
intimately tied together by Poynting's theorem and the Lorentz force law.
Whereas Maxwell's macroscopic equations relate the electric and magnetic fields
to their material sources (i.e., charge, current, polarization and
magnetization), Poynting's theorem governs the flow of electromagnetic energy
and its exchange between fields and material media, while the Lorentz law
regulates the back-and-forth transfer of momentum between the media and the
fields. As it turns out, an alternative force law, first proposed in 1908 by
Einstein and Laub, exists that is consistent with Maxwell's macroscopic
equations and complies with the conservation laws as well as with the
requirements of special relativity. While the Lorentz law requires the
introduction of hidden energy and hidden momentum in situations where an
electric field acts on a magnetic material, the Einstein-Laub formulation of
electromagnetic force and torque does not invoke hidden entities under such
circumstances. Moreover, the total force and the total torque exerted by
electromagnetic fields on any given object turn out to be independent of
whether force and torque densities are evaluated using the Lorentz law or in
accordance with the Einstein-Laub formulas. Hidden entities aside, the two
formulations differ only in their predicted force and torque distributions
throughout material media. Such differences in distribution are occasionally
measurable, and could serve as a guide in deciding which formulation, if
either, corresponds to physical reality.",1312.3262v1
2014-12-10,Measuring the bulk Lorentz factors of gamma-ray bursts with Fermi,"Gamma-ray bursts (GRBs) are powered by ultra-relativistic jets. Usually a
minimum value of the Lorentz factor of the relativistic bulk motion is obtained
based on the argument that the observed high energy photons ($\gg {\rm MeV}$)
can escape without suffering from absorption due to pair production. The exact
value, rather than a lower limit, of the Lorentz factor can be obtained if the
spectral cutoff due to such absorption is detected. With the good spectral
coverage of the Large Area Telescope (LAT) on \textsl{Fermi}, measurements of
such cutoff become possible, and two cases (GRB~090926A and GRB~100724B) have
been reported to have high-energy cutoffs or breaks. We systematically search
for such high energy spectral cutoffs/breaks from the LAT and the Gamma-ray
burst monitor (GBM) observations of the prompt emission of GRBs detected since
August 2011. Six more GRBs are found to have cutoff-like spectral feature at
energies of $\sim10-500$~MeV. Assuming that these cutoffs are caused by
pair-production absorption within the source, the bulk Lorentz factors of these
GRBs are obtained. We further find that the Lorentz factors are correlated with
the isotropic gamma-ray luminosity of the bursts, indicating that more powerful
GRB jets move faster.",1412.3342v3
2014-12-29,An operational approach to spacetime symmetries: Lorentz transformations from quantum communication,"In most approaches to fundamental physics, spacetime symmetries are
postulated a priori and then explicitly implemented in the theory. This
includes Lorentz covariance in quantum field theory and diffeomorphism
invariance in quantum gravity, which are seen as fundamental principles to
which the final theory has to be adjusted. In this paper, we suggest, within a
much simpler setting, that this kind of reasoning can actually be reversed, by
taking an operational approach inspired by quantum information theory. We
consider observers in distinct laboratories, with local physics described by
the laws of abstract quantum theory, and without presupposing a particular
spacetime structure. We ask what information-theoretic effort the observers
have to spend to synchronize their descriptions of local physics. If there are
""enough"" observables that can be measured universally on several different
quantum systems, we show that the observers' descriptions are related by an
element of the orthochronous Lorentz group O^+(3,1), together with a global
scaling factor. Not only does this operational approach predict the Lorentz
transformations, but it also accurately describes the behavior of relativistic
Stern-Gerlach devices in the WKB approximation, and it correctly predicts that
quantum systems carry Lorentz group representations of different spin. This
result thus hints at a novel information-theoretic perspective on spacetime.",1412.8462v6
2015-01-08,Information-Entropic for Travelling Solitons in Lorentz and CPT Breaking Systems,"In this work we group three research topics apparently disconnected, namely
solitons, Lorentz symmetry breaking and entropy. Following a recent work [Phys.
Lett. B 713 (2012) 304], we show that it is possible to construct in the
context of travelling wave solutions a configurational entropy measure in
functional space, from the field configurations. Thus, we investigate the
existence and properties of travelling solitons in Lorentz and CPT breaking
scenarios for a class of models with two interacting scalar fields. Here, we
obtain a complete set of exact solutions for the model studied which display
both double and single-kink configurations. In fact, such models are very
important in applications that include Bloch branes, Skyrmions, Yang-Mills,
Q-balls, oscillons and various superstring-motivated theories. We find that the
so-called Configurational Entropy (CE) for travelling solitons, which we name
as travelling Configurational Entropy (TCE), shows that the best value of
parameter responsible to break the Lorentz symmetry is one where the energy
density is distributed equally around the origin. In this way, the
information-theoretical measure of travelling solitons in Lorentz symmetry
violation scenarios opens a new window to probe situations where the parameters
responsible for breaking the symmetries are random. In this case, the TCE
selects the best value.",1501.02000v2
2015-04-15,D-Oscillons in the Standard Model-Extension,"In this work we investigate the consequences of the Lorentz symmetry
violation on extremely long-living, time-dependent, and spatially localized
field configurations, named oscillons. This is accomplished in ($D+1$)
dimensions for two interacting scalar field theories in the so-called Standard
Model-Extension context. We show that $D$-dimensional scalar field lumps can
present a typical size $R_{\min }\ll R_{KK}$, where $R_{KK}$ is the associated
length scale of extra dimensions in Kaluza-Klein theories. Here, the size
$R_{\min }$ is shown to strongly depend on the terms that control the Lorentz
violation of the theory. This implies either contraction or dilation of the
average radius $R_{\min}$, and a new rule for its composition, likewise.
Moreover, we show that the spatial dimensions for existence of oscillating
lumps have an upper limit, opening new possibilities to probe the existence of
a $D$ -dimensional oscillons at TeV energy scale. Moreover, in a cosmological
scenario with Lorentz symmetry breaking, we argue that in the early Universe
with an extremely high energy density and a strong Lorentz violation, the
typical size $R_{\min }$ was highly dilated. With the expansion and subsequent
cooling of the Universe, we propose that it passed through a phase transition
towards a Lorentz symmetry, wherein $R_{\min }$ tends to be compact.",1504.04038v2
2015-07-15,Variation of bulk Lorentz factor in AGN jets due to Compton rocket in a complex photon field,"Radio-loud active galactic nuclei are among the most powerful objects in the
universe. In these objects, most of the emission comes from relativistic jets
getting their power from the accretion of matter onto supermassive black holes.
However, despite the number of studies, a jet's acceleration to relativistic
speeds is still poorly understood.
  It is widely known that jets contain relativistic particles that emit
radiation through several physical processes, one of them being the inverse
Compton scattering of photons coming from external sources. In the case of a
plasma composed of electrons and positrons continuously heated by the
turbulence, inverse Compton scattering can lead to relativistic bulk motions
through the Compton rocket effect. We investigate this process and compute the
resulting bulk Lorentz factor in the complex photon field of an AGN composed of
several external photon sources.
  We consider various sources here: the accretion disk, the dusty torus, and
the broad line region. We take their geometry and anisotropy carefully into
account in order to numerically compute the bulk Lorentz factor of the jet at
every altitude.
  The study, made for a broad range of parameters, shows interesting and
unexpected behaviors of the bulk Lorentz factor, exhibiting acceleration and
deceleration zones in the jet. We investigate the patterns of the bulk Lorentz
factor along the jet depending on the source sizes and on the observation angle
and we finally show that these patterns can induce variability in the AGN
emission with timescales going from hours to months.",1507.04276v1
2016-02-10,A Lorentz Violating Theory: Its Nonminimal Extension in the Photon Sector,"The relentless efforts of the physics community has not yet availed us the
solution of how to unify the Quantum Mechanics with General Relativity, a
puzzle that has engaged the minds of the physicists for almost a century. The
insufficiency of today's and foreseeable future's technology for a direct reach
into the Planck energies at which the fundamental theory, the Quantum Theory of
Gravity, lies has lead to the search of the low energy effects of that
fundamental Planck level theory irregardless of the details of it. In this
thesis, one of the leading candidates of such an exotic effect, that is the
violation of Lorentz and CPT symmetries is analyzed. The action level effective
field theoretical framework for such an analysis called Standard Model
Extension has already been in the literature for the last two decades; here,
the nonminimal photon sector of such a framework is examined from a quantum
field theoretical point of view. All possible polarization vectors for
different kinds of CPT violations, the generic forms of the dispersion
relations that these polarization vectors satisfy, and the corresponding
propagators of the photon field are explicitly calculated. Special models of
Lorentz violations are introduced, and a particular one called vacuum
orthogonal model is analyzed extensively. It is found that this particular form
of Lorentz violation cannot induce any effects that is detectable in the vacuum
propagation of the photon. Isotropic and leading order cases of the Lorentz
violation is studied and this found result is explicitly shown.",1602.07676v1
2016-06-20,Lorentz factor distribution of blazars from the optical Fundamental plane of black hole activity,"Blazar radiation is dominated by a relativistic jet which can be modeled at
first approximation using just two intrinsic parameters - the Lorentz factor
$\Gamma$ and the viewing angle $\theta$. Blazar jet observations are often
beamed due to relativistic effects, complicating the understanding of these
intrinsic properties. The most common way to estimate blazar Lorentz factors
needs the estimation of apparent jet speeds and Doppler beaming factors. We
present a new and independent method of constructing the blazar Lorentz factor
distribution, using the optical fundamental plane of black hole activity. The
optical fundamental plane is a plane stretched out by both the supermassive
black holes and the X-ray binaries, in the 3D space provided by their [OIII]
line luminosity, radio luminosity and black hole mass. We use the intrinsic
radio luminosity obtained from the optical fundamental plane to constrain the
boosting parameters of the VLBA Imaging and Polarimetry Survey (VIPS) blazar
sample. We find a blazar bulk Lorentz factor distribution in the form of a
power law as $N(\Gamma) \propto \Gamma^{-2.1 \pm 0.4}$ for the $\Gamma$ range
of 1 to 40. We also discuss the viewing angle distribution of the blazars and
the dependence of our results on the input parameters.",1606.06147v1
2018-04-01,Surfaces of revolution with prescribed mean and skew curvatures in Lorentz-Minkowski space,"In this work, we investigate the problem of finding surfaces in the
Lorentz-Minkowski 3-space with prescribed skew ($S$) and mean ($H$) curvatures,
which are defined through the discriminant of the characteristic polynomial of
the shape operator and its trace, respectively. After showing that $H$ and $S$
can be interpreted in terms of the expected value and standard deviation of the
normal curvature seen as a random variable, we address the problem of
prescribed curvatures for surfaces of revolution. For surfaces with a
non-lightlike axis and prescribed $H$, the strategy consists in rewriting the
equation for $H$, which is initially a nonlinear second order Ordinary
Differential Equation (ODE), as a linear first order ODE with coefficients in a
certain ring of hypercomplex numbers along the generating curves: complex
numbers for curves on a spacelike plane and Lorentz numbers for curves on a
timelike plane. We also solve the problem for surfaces of revolution with a
lightlike axis by using a certain ODE with real coefficients. On the other
hand, for the skew curvature problem, we rewrite the equation for $S$, which is
initially a nonlinear second order ODE, as a linear first order ODE with real
coefficients. In all the problems, we are able to find the parameterization for
the generating curves in terms of certain integrals of $H$ and $S$.",1804.00259v4
2019-05-08,Functional dependence of the Hall viscosity-induced transverse voltage in two-dimensional Fermi liquids,"The breaking of parity and time-reversal symmetry in two-dimensional Fermi
liquids gives rise to non-dissipative transport features characterized by the
Hall viscosity. In magnetic fields, the Hall viscous force directly competes
with the Lorentz force, since both mechanisms contribute to the Hall voltage.
In this work, we present a channel geometry that allows us to uniquely
distinguish these two contributions and derive, for the first time, their
functional dependency on all external parameters. We show that the ratio of the
Hall viscous to the Lorentz force contribution is negative and that its modulus
decreases with increasing width, slip-length and carrier density, while it
increases with the electron-electron mean free path of our channel. In typical
materials such as GaAs the Hall viscous contribution can dominate the Lorentz
signal up to a few tens of millitesla until the total Hall voltage vanishes and
subsequently is overcome by the Lorentz contribution. Moreover, we prove that
the total Hall electric field is parabolic due to Lorentz effects, whereas the
offset of this parabola is characterized by the Hall viscosity. Hence, our
results pave the way to measure and identify the Hall viscosity via both global
and local voltage measurements.",1905.03269v3
2020-07-10,Magnetic effects on fields morphologies and reversals in geodynamo simulations,"The dynamo effect is the most popular candidate to explain the non-primordial
magnetic fields of astrophysical objects. Although many systematic studies of
parameters have already been made to determine the different dynamical regimes
explored by direct numerical geodynamo simulations, it is only recently that
the regime corresponding to the outer core of the Earth characterized by a
balance of forces between the Coriolis and Lorentz forces is accessible
numerically. In most previous studies, the Lorentz force played a relatively
minor role. For example, they have shown that a purely hydrodynamic parameter
(the local Rossby number $Ro_\ell$ determines the stability domain of dynamos
dominated by the axial dipole (dipolar dynamos).
  In this study, we show that this result cannot hold when the Lorentz force
becomes dominant. We model turbulent geodynamo simulations with a strong
Lorentz force by varying the important parameters over several orders of
magnitude. This method enables us to question previous results and to argue on
the applications of numerical dynamos in order to better understand the
geodynamo problem. Strong dipolar fields considerably affect the kinetic energy
distribution of convective motions which enables the maintenance of this field
configuration. The relative importance of each force depends on the spatial
length scale, whereas $Ro_\ell$ is a global output parameter which ignores the
spatial dependency. We show that inertia does not induce a dipole collapse as
long as the Lorentz and the Coriolis forces remain dominant at large length
scales.",2007.05530v1
2010-05-06,"Covariant isolation from an Abelian gauge field of its nondynamical potential, which, when fed back, can transform into a ""confining Yukawa""","For Abelian gauge theory a properly relativistic gauge is developed by
supplementing the Lorentz condition with causal determination of the time
component of the four-vector potential by retarded Coulomb transformation of
the charge density. This causal Lorentz gauge agrees with the Coulomb gauge for
static charge densities, but allows the four-vector potential to have a
longitudinal component that is determined by the time derivative of the
four-vector potential's time component. Just as in Coulomb gauge, the two
transverse components of the four-vector potential are its sole dynamical part.
The four-vector potential in this gauge covariantly separates into a dynamical
transverse four-vector potential and a nondynamical timelike/longitudinal
four-vector potential, where each of these two satisfies the Lorentz condition.
In fact, analogous partition of the conserved four-current shows each to
satisfy a Lorentz-condition Maxwell equation system with its own conserved
four-current. Because of this complete separation, either of these four-vector
potentials can be tinkered with without affecting its counterpart. Since it
satisfies the Lorentz condition, the nondynamical four-vector potential times a
constant with dimension of inverse length squared is itself a conserved
four-current, and so can be fed back into its own source current, which
transforms its time component into an extended Yukawa, with both exponentially
decaying and exponentially growing components. The latter might be the
mechanism of quark-gluon confinement: in non-Abelian color gauge theory the
Yukawa mixture ratio ought to be tied to color, with palpable consequences for
""colorful"" hot quark-gluon plasmas.",1005.1101v1
2018-05-11,Lorentz and CPT Tests with Clock-Comparison Experiments,"Clock-comparison experiments are among the sharpest existing tests of Lorentz
symmetry in matter. We characterize signals in these experiments arising from
modifications to electron or nucleon propagators and involving Lorentz- and
CPT-violating operators of arbitrary mass dimension. The spectral frequencies
of the atoms or ions used as clocks exhibit perturbative shifts that can depend
on the constituent-particle properties and can display sidereal and annual
variations in time. Adopting an independent-particle model for the electronic
structure and the Schmidt model for the nucleus, we determine observables for a
variety of clock-comparison experiments involving fountain clocks,
comagnetometers, ion traps, lattice clocks, entangled states, and antimatter.
The treatment demonstrates the complementarity of sensitivities to Lorentz and
CPT violation among these different experimental techniques. It also permits
the interpretation of some prior results in terms of bounds on nonminimal
coefficients for Lorentz violation, including first constraints on nonminimal
coefficients in the neutron sector. Estimates of attainable sensitivities in
future analyses are provided. Two technical appendices collect relationships
between spherical and cartesian coefficients for Lorentz violation and provide
explicit transformations converting cartesian coefficients in a laboratory
frame to the canonical Sun-centered frame.",1805.04499v1
2008-07-11,Unravelling Lorentz Covariance and the Spacetime Formalism,"We report the discovery of an exact mapping from Galilean time and space
coordinates to Minkowski spacetime coordinates, showing that Lorentz covariance
and the spacetime construct are consistent with the existence of a dynamical
3-space, and ""absolute motion"". We illustrate this mapping first with the
standard theory of sound, as vibrations of a medium, which itself may be
undergoing fluid motion, and which is covariant under Galilean coordinate
transformations. By introducing a different non-physical class of space and
time coordinates it may be cast into a form that is covariant under ""Lorentz
transformations"" wherein the speed of sound is now the ""invariant speed"". If
this latter formalism were taken as fundamental and complete we would be lead
to the introduction of a pseudo-Riemannian ""spacetime"" description of sound,
with a metric characterised by an ""invariant speed of sound"". This analysis is
an allegory for the development of 20th century physics, but where the Lorentz
covariant Maxwell equations were constructed first, and the Galilean form was
later constructed by Hertz, but ignored. It is shown that the Lorentz
covariance of the Maxwell equations only occurs because of the use of
non-physical space and time coordinates. The use of this class of coordinates
has confounded 20th century physics, and resulted in the existence of a
""flowing"" dynamical 3-space being overlooked. The discovery of the dynamics of
this 3-space has lead to the derivation of an extended gravity theory as a
quantum effect, and confirmed by numerous experiments and observations.",0807.1767v1
2014-06-23,Spontaneous Lorentz Violation: The Case of Infrared QED,"It is by now clear that infrared sector of QED has an intriguingly complex
structure. Based on earlier pioneering works on this subject, two of us
recently proposed a simple modification of QED by constructing a generalization
of the $U(1)$ charge group of QED to the ""Sky"" group incorporating the known
spontaneous Lorentz violation due to infrared photons, but still compatible in
particular with locality. There it was shown that the ""Sky"" group is generated
by the algebra of angle dependent charges and a study of its superselection
sectors has revealed a manifest description of spontaneous breaking of Lorentz
symmetry. We further elaborate this approach here and investigate in some
detail the properties of charged particles dressed by the infrared photons. We
find that Lorentz violation due to soft photons may be manifestly codified in
an angle dependent fermion mass modifying therefore the fermion dispersion
relations. The fact that the masses of the charged particles are not Lorentz
invariant affects their spin content too.Time dilation formulae for decays
should also get corrections. We speculate that these effects could be measured
possibly in muon decay experiments.",1406.5845v3
2018-09-24,Mirrors and field sources in a Lorentz-violating scalar field theory,"In this paper we consider different classical effects in a model for a scalar
field incorporating Lorentz symmetry breaking due to the presence of a single
background vector v^{\mu} coupled to its derivative. We perform an
investigation of the interaction energy between stationary steady sources
concentrated along parallel branes with an arbitrary number of dimensions, and
derive from this study some physical consequences. For the case of the scalar
dipole we show the emergence of a nontrivial torque, which is distinctive sign
of the Lorentz violation. We also investigate a similar model in the presence
of a semi-transparent mirror. For a general relative orientation between the
mirror and the v^{\mu}, we are able to perform calculations perturbatively in
v^{\mu} up to second order. We also find results without recourse to
approximations for two special cases, that of the mirror and v^{\mu} being
parallel or perpendicular to each other. For all these configurations, the
propagator for the scalar field and the interaction force between the mirror
and a point-like field source are computed. It is shown that the image method
is valid in our model for the Dirichlet's boundary condition, and we argue that
this is a non-trivial result. We also show the emergence of a torque on the
mirror depending on its orientation with respect to the Lorentz violating
background. This is a new effect with no counterpart in theories with Lorentz
symmetry in the presence of mirrors.",1809.08883v2
2019-10-02,Lorentz Factors of compact jets in Black hole X-ray binaries,"Compact, continuously launched jets in black hole X-ray binaries (BHXBs)
produce radio to optical-infrared synchrotron emission. In most BHXBs, an
infrared (IR) excess (above the disc component) is observed when the jet is
present in the hard spectral state. We investigate why some BHXBs have
prominent IR excesses and some do not, quantified by the amplitude of the IR
quenching or recovery over the transition from/to the hard state. We find that
the amplitude of the IR excess can be explained by inclination dependent
beaming of the jet synchrotron emission, and the projected area of the
accretion disc. Furthermore, we see no correlation between the expected and the
observed IR excess for Lorentz factor 1, which is strongly supportive of
relativistic beaming of the IR emission, confirming that the IR excess is
produced by synchrotron emission in a relativistic outflow. Using the amplitude
of the jet fade and recovery over state transitions and the known orbital
parameters, we constrain for the first time the bulk Lorentz factor range of
compact jets in several BHXBs (with all the well-constrained Lorentz factors
lying in the range of $\Gamma$ = 1.3 - 3.5). Under the assumption that the
Lorentz factor distribution of BHXB jets is a power-law, we find that
N($\Gamma$) $\propto \Gamma^{ -1.88^{+0.27}_{-0.34}}$. We also find that the
very high amplitude IR fade/recovery seen repeatedly in the BHXB GX 339-4
favors a low inclination angle ($< 15^\circ$) of the jet.",1910.01151v1
2019-10-29,Lorentz Force Evolution Reveals the Energy Buildup Processes during Recurrent Eruptive Solar Flares,"The energy release and build-up processes in the solar corona have
significant implications in particular for the case of large recurrent flares,
which pose challenging questions about the conditions that lead to the episodic
energy release processes. It is not yet clear whether these events occur due to
the continuous supply of free magnetic energy to the solar corona or because
not all of the available free magnetic energy is released during a single major
flaring event. In order to address this question, we report on the evolution of
photospheric magnetic field and the associated net Lorentz force changes in ARs
11261 and 11283, each of which gave rise to recurrent eruptive M- and X-class
flares. Our study reveals that after the abrupt downward changes during each
flare, the net Lorentz force increases by (2-5)x10^22 dyne in between the
successive flares. This distinct rebuild-up of net Lorentz forces is the first
observational evidence found in the evolution of any non-potential parameter of
solar active regions (ARs), which suggests that new energy was supplied to the
ARs in order to produce the recurrent large flares. The rebuild-up of magnetic
free energy of the ARs is further confirmed by the observations of continuous
shearing motion of moving magnetic features of opposite polarities near the
polarity inversion line. The evolutionary pattern of the net Lorentz force
changes reported in this study has significant implications, in particular, for
the forecasting of recurrent large eruptive flares from the same AR and hence
the chances of interaction between the associated CMEs.",1910.13264v1
2020-12-14,The mass-energy equivalence and length contraction are consistent with compression of a fluidic aether with a speed of sound equal to the speed of light,"The Lorentz aether theory was the mathematically equivalent precursor to the
special theory of relativity (SR). It assumed the existence of a static aether
filling space in which particles are affected by the Lorentz factor for length
contraction to explain the null result of the Michelson-Morley experiment.
However, it was early abandoned in favour of SR due to the apparent arbitrary
introduction of the Lorentz factor. The aether has thereafter been assumed not
to exist as it is seemingly undetectable and not needed for the SR. In this
discussion paper it is argued that this reasoning to reject the aether is
unfounded since the Lorentz factor also appears as an increased resistance term
in fluid dynamics when the speed of sound is approached. This means that, for
example, particle accelerator tests of the Lorentz factor can be interpreted as
a form of detection of a fluidic aether. Furthermore, it is shown that the
mass-energy equivalence is identical to the energy for compression of a fluid
with the speed of sound equal to the speed of light. It is thus possible that
the aether not only exists but that it also is the matter all particles are
made of.",2012.07395v1
2017-09-21,"Force, Torque, Linear Momentum, and Angular Momentum in Classical Electrodynamics","The classical theory of electrodynamics is built upon Maxwell's equations and
the concepts of electromagnetic (EM) field, force, energy, and momentum, which
are intimately tied together by Poynting's theorem and by the Lorentz force
law. Whereas Maxwell's equations relate the fields to their material sources,
Poynting's theorem governs the flow of EM energy and its exchange between
fields and material media, while the Lorentz law regulates the back-and-forth
transfer of momentum between the media and the fields. An alternative force
law, first proposed by Einstein and Laub, exists that is consistent with
Maxwell's equations and complies with the conservation laws as well as with the
requirements of special relativity. While the Lorentz law requires the
introduction of hidden energy and hidden momentum in situations where an
electric field acts on a magnetized medium, the Einstein-Laub (E-L) formulation
of EM force and torque does not invoke hidden entities under such
circumstances. Moreover, total force/torque exerted by EM fields on any given
object turns out to be independent of whether the density of force/torque is
evaluated using the law of Lorentz or that of Einstein and Laub. Hidden
entities aside, the two formulations differ only in their predicted force and
torque distributions inside matter. Such differences in distribution are
occasionally measurable, and could serve as a guide in deciding which
formulation, if either, corresponds to physical reality.",1709.07444v1
2017-11-07,Neutrino Pair Cerenkov Radiation for Tachyonic Neutrinos,"The emission of a charged light lepton pair by a superluminal neutrino has
been identified as a major factor in the energy loss of highly energetic
neutrinos. The observation of PeV neutrinos by IceCube implies their stability
against lepton pair Cerenkov radiation. Under the assumption of a
Lorentz-violating dispersion relation for highly energetic superluminal
neutrinos, one may thus constrain the Lorentz-violating parameters. A
kinematically different situation arises when one assumes a Lorentz-covariant,
space-like dispersion relation for hypothetical tachyonic neutrinos, as an
alternative to Lorentz-violating theories. We here discuss a hitherto neglected
decay process, where a highly energetic tachyonic neutrinos may emit other
(space-like, tachyonic) neutrino pairs. We find that the space-like dispersion
relation implies the absence of a q^2 threshold for the production of a
tachyonic neutrino-antineutrino pair, thus leading to the dominant additional
energy loss mechanism for an oncoming tachyonic neutrino in the medium-energy
domain. Surprisingly, the small absolute value of the decay rate and energy
loss rate in the tachyonic model imply that these models, in contrast to the
Lorentz-violating theories, are not pressured by the cosmic PeV neutrinos
registered by the IceCube collaboration.",1711.02660v1
2017-11-14,One-loop renormalization of Lorentz/CPT violating scalar field theory in curved space-time,"The one-loop divergences for the scalar field theory with Lorentz and/or CPT
breaking terms are obtained in curved space-time. We analyze two separate
cases: minimal coupled scalar field with gravity and nonminimal one. For the
minimal case with real scalar field, the counterterms are evaluated in a
nonperturbative form in the CPT-even parameter through a redefinition of
space-time metric. In the most complicated case of complex scalar field
nonminimally interacting with gravity, the solution for the divergences is
obtained in the first order in the weak Lorentz violating parameter. The
necessary form of the vacuum counterterms indicate the most important
structures of Lorentz/CPT violations in the pure gravitational sector of
theory. The conformal theory limit is also analyzed. It turns out that if we
allow the violating fields to transform, the classical conformal invariance of
massless scalar fields can be maintained in the $\,\xi = 1/6\,$ case. At
quantum level the conformal symmetry is violated by trace anomaly. As a result,
conformal anomaly and the anomaly-induced effective action are evaluated in the
presence of extra Lorentz- and/or CPT-violating parameters. Such gravitational
effective action is important for cosmological applications and can be used for
searching of Lorentz violation in primordial universe in the cosmological
perturbations, especially gravitational waves.",1711.05193v1
2018-03-12,Perturbative generation of photon Lorentz violating terms from a pseudo-tensor Lorentz-breaking extension of QED,"We consider an extended QED with the addition of a dimension-five
Lorentz-breaking coupling between spinor and gauge fields, involving a
pseudo-tensor $\kappa^{\mu\nu\lambda\rho}$. The specific form of the Lorentz
violating coupling considered by us have been suggested in other works, and
some of its consequences at the classical level were already studied. Here, we
investigate the consequences of this specific form of Lorentz violation at the
quantum level, evaluating the one loop corrections to the gauge field two-point
function, both at zero and at finite temperature. We relate the terms that are
generated by quantum corrections with the photon sector of the Standard Model
Extension, discussing the possibility of establishing experimental bounds on
$k^{\mu\nu\rho\sigma}$. From the dispersion relations in the resulting theory,
we discuss its consistency from the causality viewpoint.",1803.04308v3
2018-03-23,Generalized AdS-Lorentz deformed supergravity on a manifold with boundary,"The purpose of this paper is to explore the supersymmetry invariance of a
particular supergravity theory, which we refer to as D=4 generalized
AdS-Lorentz deformed supergravity, in the presence of a non-trivial boundary.
In particular, we show that the so-called generalized minimal AdS-Lorentz
superalgebra can be interpreted as a peculiar torsion deformation of osp(4|1),
and we present the construction of a bulk Lagrangian based on the
aforementioned generalized AdS-Lorentz superalgebra. In the presence of a
non-trivial boundary of space-time, that is when the boundary is not thought of
as set at infinity, the fields do not asymptotically vanish, and this has some
consequences on the invariances of the theory, in particular on supersymmetry
invariance. In this work, we adopt the so-called rheonomic (geometric) approach
in superspace and show that a supersymmetric extension of a Gauss-Bonnet like
term is required in order to restore the supersymmetry invariance of the
theory. The action we end up with can be recast as a MacDowell-Mansouri type
action, namely as a sum of quadratic terms in the generalized AdS-Lorentz
covariant super field-strengths.",1803.08738v4
2020-05-04,Symmetries from Locality. II. Gravitation and Lorentz Boosts,"It is known that local, Lorentz invariant, unitary theories involving
particles with spin 1 demand that the matter sector they couple to are
organized by internal physical symmetries and the associated charge
conservation, while spin 3/2 demands supersymmetry. However, the introduction
of a spin 2 graviton does not obviously demand new symmetries of the matter
sector (although it does demand a universal coupling). In this work we relax
the assumption of Lorentz boost symmetry, while maintaining a basic notion of
locality that there is no instantaneous signaling at a distance. This extends
and complements our accompanying work in Part 1 on related issues for spin 1
particles in electromagnetism. In order to avoid potential problems with
longitudinal modes of the graviton, we choose to project them out, leaving only
two degrees of freedom. We study large classes of theories that a priori may
violate Lorentz boost invariance. By requiring the tree-level exchange action
be local, we find that consistency demands that the Lorentz boost symmetry must
be satisfied by the graviton and the matter sector, and in turn we recover
general relativity at this order of analysis.",2005.01744v3
2020-05-07,Generating primordial fluctuations from modified teleparallel gravity with local Lorentz-symmetry breaking,"In the context of modified teleparallel gravity, we study the generation of
primordial density fluctuations in a general scalar-torsion theory whose
Lagrangian density is an arbitrary function $f(T,\phi)$ of the torsion scalar
$T$ and a scalar field $\phi$, plus the kinetic term of this latter. It is well
known that generic modifications of teleparallel gravity are not invariant
under six-parameter local Lorentz transformations. In order to restore the
local Lorentz symmetry, we have incorporated six additional degrees of freedom
in the form of Goldstone modes of the symmetry breaking through a Lorentz
rotation of the tetrad field. After integrating out all the auxiliary modes, we
obtain a second order action for the scalar and tensor propagating modes and
their power spectrum generated during inflation. It is found that an explicit
mass term emerges in the second order action for curvature perturbation,
describing the imprints of local Lorentz violation at first-order of slow-roll.
We show that only inflationary models with nonminimal coupling functions
$f(T,\phi)$ which are non-linear in $T$, including the case of $f(T)$ gravity
with minimally coupled scalar field, can generate primordial fluctuations. For
a concrete model of inflation, we study the power-law potential by using the
latest Planck data.",2005.03753v3
2020-05-19,On the lightlike Lorentz violation,"We consider the lightlike spontaneous Lorentz invariance violation (SLIV)
appearing through the zero ""length-fixing"" constraint put on a gauge vector
field, $A_{\mu }A^{\mu }=0$, and discuss its physical consequences in the
framework of a conventional QED and beyond. Again, as in the timelike and
spacelike SLIV cases, $A_{\mu }A^{\mu }=\pm M_{A}^{2}$ ($M_{A}$ is a scale of
SLIV), while this constraint leads to an emergence of the Nambu-Goldstone modes
collected in physical photon, the SLIV itself is still left unobservable unless
gauge invariance in the theory is broken. At the same time, a crucial
difference with the two former cases is that the asymmetrical vacuum
corresponding to the lightlike Lorentz violation appears infinitely degenerated
with all other vacua including the symmetrical one. We show that this
degeneracy can be lifted out by introducing an extra gauge vector field being
sterile with respect to an ordinary matter, though having some potential
couplings with the basic $A_{\mu }$ field. A slight mixing of them makes the
underlying gauge invariance to be partially broken due to which physical
Lorentz invariance occurs broken as well. This may cause a variety of the
Lorentz violating processes some of which are briefly discussed.",2005.09567v3
2021-03-23,Thermal effects on the Casimir energy of a Lorentz-violating scalar in magnetic field,"In this work I investigate the finite temperature Casimir effect due to a
massive and charged scalar field that breaks Lorentz invariance in a CPT-even,
aether-like way. I study the cases of Dirichlet and mixed (Dirichlet-Neumann)
boundary conditions on a pair of parallel plates. I will not examine the case
of Neumann boundary conditions since it produces the same results as Dirichlet
boundary conditions. The main tool used in this investigation is the
$\zeta$-function technique that allows me to obtain the Helmoltz free energy
and Casimir pressure in the presence of a uniform magnetic field perpendicular
to the plates. Three cases of Lorentz asymmetry are studied: timelike,
spacelike and perpendicular to the magnetic field, spacelike and parallel to
the magnetic field. Asymptotic cases of small plate distance, high temperature,
strong magnetic field, and large mass will be considered for each of the three
types of Lorentz asymmetry and each of the two types of boundary conditions
examined. In all these cases simple and very accurate analytic expressions of
the thermal corrections to the Casimir energy and pressure are obtained and I
discover that these corrections strongly depend on the direction of the unit
vector that produces the breaking of the Lorentz symmetry.",2103.12823v1
2021-11-05,Properties of Navier-Stokes mild solutions with initial data in subcritical Lorentz spaces,"For initial data $f$ in a subcritical Lorentz space $L^{p,q}(\mathbb{R}^{n})
\hookrightarrow \dot B^{-\frac np}_{\infty,\infty}(\mathbb{R}^n)$
($n<p<\infty$, $1\leq q \leq \infty$), we prove results which imply in
particular that a local in time mild Navier-Stokes solution cannot become
unbounded in the $L^{p,q}(\mathbb{R}^{n})$-norm before it becomes unbounded in
the norm of the larger subcritical Besov space $\dot B^{-\frac
np}_{\infty,\infty}(\mathbb{R}^n)$. In view of the known local theory in such
large Besov spaces, this can be thought of as a `propagation of regularity'
type of result; here, we provide a self-contained local theory (including
scaling-appropriate `blow-up estimates', similar to those established by J.
Leray in the Lebesgue setting) in the Lorentz setting, along with uniqueness
results which imply such propagation of regularity. Our existence results are
based on the method of T. Kato (1984) with Lorentz spaces replacing Lebesgue
spaces throughout, and are given without any reference to the Besov framework.
The uniqueness results are similarly self-contained, extending certain Lebesgue
space methods of Fabes-Jones-Riviere (1972) to the Lorentz setting. We also
establish certain continuity properties of the solutions which are constructed.
(A more detailed abstract is provided in the article itself.)",2111.03520v3
2021-12-06,Constraint on parameters of a rotating black hole in Einstein-bumblebee theory by quasi-periodic oscillations,"We have studied quasi-periodic oscillations frequencies in a rotating black
hole with Lorentz symmetry breaking parameter in Einstein-bumblebee gravity by
relativistic precession model. We find that in the rotating case with non-zero
spin parameter both of the periastron and nodal precession frequencies increase
with the Lorentz symmetry breaking parameter, but the azimuthal frequency
decreases. In the non-rotating black hole case, the nodal precession frequency
disappears for arbitrary Lorentz symmetry breaking parameter. With the
observation data of GRO J1655-40, XTE J1550-564, and GRS 1915+105, we find that
the constraint on the Lorentz symmetry breaking parameter is more precise with
data of GRO J1655-40 in which the best-fit value of the Lorentz symmetry
breaking parameter is negative. This could lead to that the rotating black hole
in Einstein-bumblebee gravity owns the higher Hawking temperature and the
stronger Hawking radiation, but the lower possibility of exacting energy by
Penrose process. However, in the range of $1 \sigma$, we also find that general
relativity remains to be consistent with the observation data of GRO J1655-40,
XTE J1550-564 and GRS 1915+105.",2112.02895v3
2022-01-03,Convectively driven decadal zonal accelerations in Earth's fluid core,"Azimuthal accelerations of cylindrical surfaces co-axial with the rotation
axis have been inferred to exist in Earth's fluid core on the basis of magnetic
field observations and changes in the length-of-day. These accelerations have a
typical timescale of decades. However, the physical mechanism causing the
accelerations is not well understood. Scaling arguments suggest that the
leading order torque averaged over cylindrical surfaces should arise from the
Lorentz force. Decadal fluctuations in the magnetic field inside the core,
driven by convective flows, could then force decadal changes in the Lorentz
torque and generate zonal accelerations. We test this hypothesis by
constructing a quasi-geostrophic model of magnetoconvection, with
thermally-driven flows perturbing a steady, imposed background magnetic field.
We show that when the Alfv\'{e}n number in our model is similar to that in
Earth's fluid core, temporal fluctuations in the torque balance are dominated
by the Lorentz torque, with the latter generating mean zonal accelerations. Our
model reproduces both fast, free Alfv\'{e}n waves and slow, forced
accelerations, with ratios of relative strength and relative timescale similar
to those inferred for the Earth's core. The temporal changes in the magnetic
field which drive the time-varying Lorentz torque are produced by the
underlying convective flows, shearing and advecting the magnetic field on a
timescale associated with convective eddies. Our results support the hypothesis
that temporal changes in the magnetic field deep inside Earth's fluid core
drive the observed decadal zonal accelerations of cylindrical surfaces through
the Lorentz torque.",2201.00846v1
2022-02-07,Lorentz transformation in Maxwell equations for slowly moving media,"We use the method of field decomposition, a technique widely used in
relativistic magnetohydrodynamics, to study the small velocity approximation
(SVA) of the Lorentz transformation in Maxwell equations for slowly moving
media. The ""deformed"" Maxwell equations derived under the SVA in the lab frame
can be put into the conventional form of Maxwell equations in the medium's
comoving frame. Our results show that the Lorentz transformation in the SVA up
to $O(v/c)$ ($v$ is the speed of the medium and $c$ is the speed of light in
vacuum) is essential to derive these equations: the time and charge density
must also change when transforming to a different frame even in the SVA, not
just the position and current density as in the Galilean transformation. This
marks the essential difference of the Lorentz transformation from the Galilean
one. We show that the integral forms of Faraday and Ampere equations for slowly
moving surfaces are consistent with Maxwell equations. We also present Faraday
equation the covariant integral form in which the electromotive force can be
defined as a Lorentz scalar independent of the observer's frame. No evidences
exist to support an extension or modification of Maxwell equations.",2202.03122v3
2022-02-10,Testing Lorentz Invariance of Gravity in the Standard Model Extension with GWTC-3,"Successful detection of gravitational waves has presented a new avenue to
explore the nature of gravity. With the cumulative catalog of detected events,
we can perform tests on General Relativity from various aspects with increasing
precision. In this work, we focus on Lorentz symmetry during propagation of
gravitational waves. Considering the dispersion relation in the gauge-invariant
linearized gravity sector of the Standard-Model Extension, the anisotropy,
birefringence, and dispersion effects will be induced during propagation of
gravitational waves because of the Lorentz violating modification, and cause
dephasings in waveform received by detectors. With the distorted waveform, we
perform full Bayesian inference with confident events in the last gravitational
wave catalog. We consider two cases associated with the lowest mass dimension
$d=5,6$ which are supposed to have the most significant effects, and place the
constraints on the expansion coefficients characterizing the Lorentz violating
behavior which have 16 independent components for $d=5$ and 18 components for
$d=6$. We do not find any evidence for Lorentz violation in the gravitational
wave data, the constraints on the coefficients are on the order of
$10^{-15}{\rm m}$ for $d=5$ and $10^{-10}{\rm m^2}$ for $d=6$ respectively.",2202.05092v2
2022-03-09,"Effective drag in rotating, poorly conducting plasma turbulence","Despite the increasing sophistication of numerical models of hot Jupiter
atmospheres, the large time-scale separation required in simulating the wide
range in electrical conductivity between the dayside and nightside has made it
difficult to run fully consistent magnetohydrodynamic (MHD) models. This has
led to many studies that resort to drag parametrizations of MHD. In this study,
we revisit the question of the Lorentz force as an effective drag by running a
series of direct numerical simulations of a weakly rotating, poorly conducting
flow in the presence of a misaligned, strong background magnetic field. We find
that the drag parametrization fails once the time-scale associated with the
Lorentz force becomes shorter than the dynamical time-scale in the system,
beyond which the effective drag coefficient remains roughly constant, despite
orders-of-magnitude variation in the Lorentz (magnetic) time-scale. We offer an
improvement to the drag parametrization by considering the relevant asymptotic
limit of low conductivity and strong background magnetic field, known as the
quasi-static MHD approximation of the Lorentz force. This approximation removes
the fast time-scale associated with magnetic diffusion, but retains a more
complex version of the Lorentz force, which could be utilized in future
numerical models of hot Jupiter atmospheric circulation.",2203.04992v2
2022-05-14,Lorentz Symmetry Violation in String-Inspired Effective Modified Gravity Theories,"We discuss situations under which Lorentz symmetry is violated in effective
gravitational field theories that arise in the low-energy limit of strings. In
particular, we discuss spontaneous violation of the symmetry by the ground
state of the system. In the flat space-time limit, the effective theory of the
broken Lorentz Symmetry acquires a form that belongs to the general framework
of the so-called Standard Model Extension (SME) formalism. A brief review of
this formalism is given before we proceed to describe a concrete example, where
we discuss a Lorentz-symmetry-Violating (LV) string-inspired cosmological
model. The model is a gravitational field theory coupled to matter, which
contains torsion, arising from the fundamental degrees of freedom of the
underlying string theory. The latter, under certain conditions which we shall
specify, can acquire a LV condensate, and lead, via the appropriate equations
of motion, to solutions that violate Lorentz and CPT
(Charge-Parity-Time-Reversal) symmetry. The model is described by a specific
form of an SME effective theory, with specific LV and CPT symmetry Violating
coefficients, which depend on the microscopic parameters of the underlying
string theory, and thus can be bounded by current-era phenomenology.",2205.07044v1
2022-06-01,Improved bounds on Lorentz violation from composite-pulse Ramsey spectroscopy in a trapped ion,"In attempts to unify the four known fundamental forces in a single
quantum-consistent theory, it is suggested that Lorentz symmetry may be broken
at the Planck scale. Here we search for Lorentz violation at the low-energy
limit by comparing orthogonally oriented atomic orbitals in a
Michelson-Morley-type experiment. We apply a robust radiofrequency composite
pulse sequence in the $^2F_{7/2}$ manifold of an Yb$^+$ ion, extending the
coherence time from 200 $\mu$s to more than 1 s. In this manner, we fully
exploit the high intrinsic susceptibility of the $^2F_{7/2}$ state and take
advantage of its exceptionally long lifetime. We match the stability of the
previous best Lorentz symmetry test nearly an order of magnitude faster and
improve the constraints on the symmetry breaking coefficients to the 10$^{-21}$
level. These results represent the most stringent test of this type of Lorentz
violation. The demonstrated method can be further extended to ion Coulomb
crystals.",2206.00570v3
2022-06-16,Lorentz Symmetry Violation of Cosmic Photons,"As a basic symmetry of space-time, Lorentz symmetry has played important
roles in various fields of physics, and it is a glamorous question whether
Lorentz symmetry breaks. Since Einstein proposed special relativity, Lorentz
symmetry has withstood very strict tests, but there are still motivations for
Lorentz symmetry violation (LV) research from both theoretical consideration
and experimental feasibility, that attract physicists to work on LV theories,
phenomena and experimental tests with enthusiasm. There are many theoretical
models including LV effects, and different theoretical models predict different
LV phenomena, from which we can verify or constrain LV effects. Here, we
introduce three types of LV theories: quantum gravity theory, space-time
structure theory and effective field theory with extra-terms. Limited by the
energy of particles, the experimental tests of LV are very difficult; however,
due to the high energy and long propagation distance, high-energy particles
from astronomical sources can be used for LV phenomenological researches.
Especially with cosmic photons, various astronomical observations provide rich
data from which one can obtain various constraints for LV researches. Here, we
review four common astronomical phenomena which are ideal for LV studies,
together with current constraints on LV effects of photons.",2206.08180v1
2022-08-16,Does Lorentz-symmetric design boost network performance in jet physics?,"In the deep learning era, improving the neural network performance in jet
physics is a rewarding task as it directly contributes to more accurate physics
measurements at the LHC. Recent research has proposed various network designs
in consideration of the full Lorentz symmetry, but its benefit is still not
systematically asserted, given that there remain many successful networks
without taking it into account. We conduct a detailed study on the
Lorentz-symmetric design. We propose two generalized approaches for modifying a
network - these methods are experimented on Particle Flow Network, ParticleNet,
and LorentzNet, and exhibit a general performance gain. We also reveal that the
notable improvement attributed to the ""pairwise mass"" feature in the network is
due to its introduction of a structure that fully complies with Lorentz
symmetry. We confirm that Lorentz-symmetry preservation serves as a strong
inductive bias of jet physics, hence calling for attention to such general
recipes in future network designs.",2208.07814v3
2022-09-21,Probing non-unitarity of neutrino mixing in the scenario of Lorentz violation and dark nonstandard interaction,"Neutrino flavour oscillation is one of the primary indication of the
existence of new physics beyond standard model. The presence of small neutrino
mass is indispensable to explicate the oscillation among different flavours of
neutrino. By the addition of a right handed neutral lepton with the standard
model fermions, it is possible to generate tiny neutrino mass. Such additional
fermion may induce non-unitarity to the $3\times 3$ PMNS mixing matrix which
influences the propagation of neutrino in space-time. In this work the effect
of non-unitary mixing matrix is analyzed in neutrino oscillation in presence of
two new physics scenarios, Lorentz violation and dark non-standard interaction.
Lorentz symmetry violation mainly appears at the Planck scale, which may also
be manifested at a lower energy level. On the other hand, dark non standard
interaction arises due to the interaction of neutrino with the environmental
dark matter which contributes as a perturbative correction to the neutrino
mass. In this analysis, the comparative study of unitary and non-unitary mixing
matrix is carried out considering the scenario of Lorentz violation and dark
NSI in the context of long baseline DUNE and short baseline Daya Bay
experimental set up. The signature of dark nonstandard interaction is
observable in both DUNE and Daya Bay set up in terms of large value of neutrino
survival and oscillation probability respectively and is a possible explanation
for the excess flux observed at $\sim5$ MeV in Daya Bay experiment. The
signature of Lorentz violation is also possible to be observed in the short
baseline Daya Bay experiment only.",2209.10233v3
2023-02-21,Investigating the effects of Lorentz Invariance Violation on the CP-sensitivities of the Deep Underground Neutrino Experiment,"The neutrino oscillations offer great potential for probing new physics
effects beyond the Standard Model. Any additional effect on neutrino
oscillations can help understand the nature of these non-standard effects. The
violation of fundamental symmetries may appear as new physics effects in
various neutrino experiments. Lorentz symmetry is one such fundamental symmetry
in nature, the violation of which implies a breakdown of space-time symmetry.
The Lorentz Invariance Violation (LIV) is intrinsic in nature and its effects
exist even in a vacuum. Neutrinos can be an intriguing probe for exploring such
violations of Lorentz symmetry. The effect of violation of Lorentz Invariance
can be explored through the impact on the neutrino oscillation probabilities.
The effect of LIV is treated as a perturbation to the standard neutrino
Hamiltonian considering the Standard Model Extension (SME) framework. In this
work, we have probed the effect of LIV on the neutrino oscillation measurements
considering the Deep Underground Neutrino Experiment (DUNE) as a case study.
The inclusion of LIV affects various neutrino oscillation parameters as it
modifies the standard neutrino oscillation probabilities. We looked into the
capability of DUNE in constraining the LIV parameters and then explored the
impact of CPT-violating LIV terms on the mass-induced neutrino oscillation
probabilities. We have also probed the influence of LIV parameters on the
CP-measurement sensitivity at DUNE.",2302.10456v2
2023-10-13,Testing Lorentz symmetry with space-based gravitational-wave detectors,"Lorentz symmetry (LS), one of the most fundamental physical symmetries, has
been extensively studied in the context of quantum gravity and unification
theories. Many of these theories predict a LS violation, which could arise from
the discreteness of spacetime, or extra dimensions. Standard-model extension
(SME) is an effective field theory to describe Lorentz violation whose effects
can be explored using precision instruments such as atomic clocks and
gravitational-wave (GW) detectors. Considering the pure-gravity sector and
matter-gravity coupling sector in the SME, we studied the leading
Lorentz-violating modifications to the time delay of light and the relativistic
frequency shift of the clock in the space-based GW detectors. We found that the
six data streams from the GW mission can construct various combinations of
measurement signals, such as single-arm round-trip path, interference path,
triangular round-trip path, etc. These measurements are sensitive to the
different combinations of SME coefficients and provide novel linear
combinations of SME coefficients different from previous studies. Based on the
orbits of TianQin, LISA, and Taiji missions, we calculated the response of
Lorentz-violating effects on the combinations of the measurement signal data
streams. Our results allow us to estimate the sensitivities for SME
coefficients: $10^{-6}$ for the gravity sector coefficient $\bar{s}^{TT}$,
$10^{-6}$ for matter-gravity coupling coefficients
$(\bar{a}^{(e+p)}_{\text{eff}})_{T}$ and $\bar{c}^{(e+p)}_{TT}$, and $10^{-5}$
for $(\bar{a}^{n}_{\text{eff}})_{T}$ and $\bar{c}^{n}_{TT}$.",2310.09224v1
2023-12-18,SUSY QED with Lorentz-asymmetric fermionic matter and a glance at the electron's EDM,"This contribution sets out to pursue the investigation of a supersymmetric
electrodynamics model with Lorentz-symmetry violation (LSV) manifested by a
space-time unbalance in the propagation of the fermionic charged matter.
Despite violation of Lorentz symmetry, the supersymmetry algebra is kept
untouched. We then adopt a superspace approach to build up an
$\mathcal{N}=1$-supersymmetric Abelian gauge theory in presence of a
Lorentz-violating background supermultiplet that accommodates the space-time
asymmetry parameter of the charged matter. We describe, in this scenario, how
the particular Lorentz-symmetry breaking, brought about by the fermionic
matter, affects its (matter) scalar partners and the photon/photino that
minimally couple to charged matter. From the (modified) Dirac, Klein-Gordon and
Maxwell field equations, we work out the corresponding dispersion relations to
inspect and discuss the physical effects of the LSV Majorana fermion
condensates that naturally emerge from the background supermultiplet. Finally,
we target efforts to investigate the Gordon decomposition of the charged lepton
electromagnetic current. This is carried out by iterating the (fermion and
scalar) matter field equations, which points to an effective contribution to
the electron's electric dipole moment (EDM). This result allows us to attain an
estimate of the pseudo-vector condensate of the (LSV) Majorana background
fermion.",2312.11691v1
1995-09-21,Damped Lyman-alpha and Lyman Limit Absorbers in the Cold Dark Matter Model,"We study the formation of damped \lya and Lyman limit absorbers in a
hierarchical clustering scenario using a gas dynamical simulation of an $\Omega
= 1$, cold dark matter universe. In the simulation, these high column density
systems are associated with forming galaxies. Damped \lya absorption, $N_{HI}
\simgt 10^{20.2}\cm^{-2}$, arises along lines of sight that pass near the
centers of relatively massive, dense protogalaxies. Lyman limit absorption,
$10^{17}\cm^{-2} \simlt N_{HI} \simlt 10^{20.2}\cm^{-2}$, develops on lines of
sight that pass through the outer parts of such objects or near the centers of
smaller protogalaxies. The number of Lyman limit systems is less than observed,
while the number of damped \lya systems is quite close to the observed
abundance. Damped absorbers are typically $\sim 10$ kpc in radius, but the
population has a large total cross section because the systems are much more
numerous than present day $L_*$ galaxies. Our results demonstrate that high
column density systems like those observed arise naturally in a hierarchical
theory of galaxy formation and that it is now possible to study these absorbers
directly from numerical simulations.",9509106v1
1995-09-21,Nonlinear Damping of Oscillations in Tidal-Capture Binaries,"We calculate the damping of quadrupole f and low order g modes (primary
modes) by nonlinear coupling to other modes of the star. This damping is orders
of magnitude more rapid than direct radiative damping when the primary
amplitude is large, as in tidal capture.
  Primary modes destabilize high degree g-modes of half their frequency
(daughter modes) by 3-mode coupling in radiative zones. In sunlike stars, the
growth time $\equiv\eta^{-1}\approx 4 E_{0,42}^{-1/2}$ days, where $E_{0,42}$
is the initial energy of the primary mode in units of $10^{42}~$erg, and of
order $10^{10}E_{0,42}^{5/4}$ daughters are unstable. The growth rate is
approximately equal to the angular frequency of the primary mode times its
dimensionless radial amplitude, $\delta R/R_*\approx 0.002E_{0,42}^{1/2}$.
Although the daughter modes are limited by their own nonlinearities,
collectively they absorb most of the primary mode's energy after a time $\sim
10\eta^{-1}$ provided $E_{0}> 10^{40}~\mbox{erg}$. In fact nonlinear mode
interaction may be the dominant damping process if $E_0\gtrsim
10^{37}~\mbox{erg}$.
  Our results have application to tidally captured main sequence globular
cluster stars of mass $\ge 0.5 M_{\sun}$; the tidal energy is dissipated in the
radiative core of the star in about a month, which is less than the initial
orbital period.",9509112v1
1997-08-12,Spectroscopy of PKS 0528-260: New Limits on CO Absorption and Emission,"We have obtained a moderate resolution spectrum of the quasar PKS 0528-250
with the Red Channel Spectrograph on the Multiple Mirror Telescope (MMT) in
order to study a damped Lyman alpha absorption line system at z = 2.8115.
  We obtain a new upper limit for the CO column density for the z = 2.8108
velocity component in the z = 2.8115 damped Lyman alpha system. The ionization
of different species in this component rules out a quasar spectral energy
distribution (SED) as the ionization field,and implies an ultraviolet radiation
field intensity a few times that of the Milky Way value. The estimated total
number density is n(H) about 20 cm^{-3}. The physical size for the z = 2.8108
component implied by these models is about 40 parsecs. The ionization of
different species also suggests a structure with a hot intercloud medium
associated with a H I cloud in this component, that is, most low ionized ions
are from the cold medium where photoionization and photodissociation dominates.
The highly ionized species may be from the intercloud medium where collisional
ionization dominates. We also present newly identified Ni II absorption lines
in the z = 2.1408 and z = 2.8115 damped Ly$\alpha$ systems. The derived
depletion of nickel by dust confirms previous results that the dust-to-gas
ratio in these two damped Lyman alpha systems is about 10% of the Milky Way
ratio. Millimeter wavelength observations obtained at the NRAO 12 meter
telescope provide new upper limits on CO (3-2) emission in the z = 2.8115
damped Lyman alpha system.",9708104v1
1998-11-04,GMRT Observations of Low z Damped Lyman-alpha Absorbers,"We present Giant Metrewave Radio Telescope (GMRT) observations of redshifted
HI 21cm absorption in two low redshift (z=0.2212, z=0.0912) damped Lyman-alpha
systems seen towards the gigahertz peaked source OI 363 (z_em = 0.630). The
object at z=0.0912 is the lowest redshift damped Lyman-alpha system known to
date. Ground based imaging (Rao & Turnshek, 1998) shows that at neither
redshift is there a large spiral galaxy at low impact parameter to the line of
sight to OI 363, in contradiction with the suggestion that these systems are
large proto-disks.
  Since OI 363 is a highly compact, core dominated source, the covering factor
of the HI gas is likely to be unity. Nonetheless, the spin temperatures derived
from the 21cm optical depth (and using the N_HI measured from HST spectra, Rao
& Turnshek, 1998) are high, viz. 1120 +/- 200 K and 825 +/- 110 K for the high
and low redshift systems respectively. These values are considerably higher
than typical values (100 - 200 K) measured in our Galaxy and Andromeda and are,
in fact, similar to those obtained in high redshift damped Lyman-alpha systems.
Our observations hence suggest that evolutionary effects may not be crucial in
understanding the difference in derived spin temperature values between local
spiral disks and high redshift damped Lyman-alpha systems.",9811068v1
2002-01-25,Galaxies Associated with z~4 Damped Lya Systems: I. Imaging and Photometric Selection,"This paper describes the acquisition and analysis of imaging data for the
identification of galaxies associated with z~4 damped Lya systems. We present
deep BRI images of three fields known to contain four z~4 damped systems. We
discuss the reduction and calibration of the data, detail the color criteria
used to identify z~4 galaxies, and present a photometric redshift analysis to
complement the color selection. We have found no galaxy candidates closer to
the QSO than 7'' which could be responsible for the damped Lya systems.
Assuming that at least one of the galaxies is not directly beneath the QSO, we
set an upper limit on this damped Lya system of L < L*/4. Finally, we have
established a web site to release these imaging data to the public.",0201417v2
2002-02-25,Eccentricity Evolution for Planets in Gaseous Disks,"We investigate the hypothesis that interactions between a giant planet and
the disk from which it forms promote eccentricity growth. These interactions
are concentrated at discrete Lindblad and corotation resonances. Interactions
at principal Lindblad resonances cause the planet's orbit to migrate and open a
gap in the disk if the planet is sufficiently massive. Those at first order
Lindblad and corotation resonances change the planet's orbital eccentricity.
Eccentricity is excited by interactions at external Lindblad resonances which
are located on the opposite side of corotation from the planet, and damped by
co-orbital Lindblad resonances which overlap the planet's orbit. If the planet
clears a gap in the disk, the rate of eccentricity damping by co-orbital
Lindblad resonances is reduced. Density gradients associated with the gap
activate eccentricity damping by corotation resonances at a rate which
initially marginally exceeds that of eccentricity excitation by external
Lindblad resonances. But the corotation torque drives a mass flux which reduces
the density gradient near the resonance. Sufficient partial saturation of
corotation resonances can tip the balance in favor of eccentricity excitation.
A minimal initial eccentricity of a few percent is required to overcome viscous
diffusion which acts to unsaturate corotation resonances by reestablishing the
large scale density gradient. Thus eccentricity growth is a finite amplitude
instability. Formally, interactions at the apsidal resonance, which is a
special kind of co-orbital Lindblad resonance, appears to damp eccentricity
faster than external Lindblad resonances can excite it. However, apsidal waves
have such long wavelengths that they do not propagate in protoplanetary disks.
This reduces eccentricity damping by the apsidal resonance to a modest level.",0202462v1
2003-07-23,Dusty Molecular Cloud Collapse in the Presence of Alfvén Waves,"It has been shown that magnetic fields play an important role in the
stability of molecular clouds, mainly perpendicularly to the field direction.
However, in the parallel direction the stability is a serious problem still to
be explained. Interstellar turbulence may allow the generation of Alfv\'en
waves that propagate through the clouds in the magnetic field direction. These
regions also present great amounts of dust particles which can give rise to new
wave modes, or modify the pre-existing ones. The dust-cyclotron damping affects
the Alfv\'en wave propagation near the dust- cyclotron frequency. On the other
hand, the clouds present different grain sizes, which carry different charges.
In this sense, a dust particle distribution has several dust-cyclotron
frequencies and it will affect a broad band of wave frequencies. In this case,
the energy transfer to the gas is more efficient than in the case where the
ion-cyclotron damping is considered alone. This effect becomes more important
if a power law spectrum is considered for the wave energy flux, since the major
part of the energy is concentrated in low-frequency waves. In this work we
calculate the dust- cyclotron damping in a dusty and magnetized dwarf molecular
cloud, as well as determine the changes in the Alfv\'en wave flux. Then, we use
these results to study the gravitational stability of the cloud. We show that,
considering the presence of charged dust particles, the wave flux is rapidly
damped due to dust-cyclotron damping. Then the wave pressure acts in a small
length scale, and cannot explain the observable cloud sizes, but can explain
the existence of small and dense cores.",0307411v1
2005-02-28,Thermal Evolution of a Pulsating Neutron Star,"We have derived a set of equations to describe the thermal evolution of a
neutron star which undergoes small-amplitude radial pulsations. We have taken
into account, in the frame of the General Theory of Relativity, the pulsation
damping due to the bulk and shear viscosity and the accompanying heating of the
star. The neutrino emission of a pulsating non-superfluid star and its heating
due to the bulk viscosity are calculated assuming that both processes are
determined by the non-equilibrium modified Urca process. Analytical and
numerical solutions to the set of equations of the stellar evolution are
obtained for linear and strongly non-linear deviations from beta-equilibrium.
It is shown that a pulsating star may be heated to very high temperatures,
while the pulsations damp very slowly with time (a power law damping for
100-1000 years), as long as the damping is determined by the bulk viscosity.
The contribution of the shear viscosity to the damping becomes important in a
rather cool star with a low pulsation energy.",0502583v2
2005-05-02,Collisionless Damping of Fast MHD Waves in Magneto-rotational Winds,"We propose collisionless damping of fast MHD waves as an important mechanism
for the heating and acceleration of winds from rotating stars. Stellar rotation
causes magnetic field lines anchored at the surface to form a spiral pattern
and magneto-rotational winds can be driven. If the structure is a magnetically
dominated, fast MHD waves generated at the surface can propagate almost
radially outward and cross the field lines. The propagating waves undergo
collisionless damping owing to interactions with particles surfing on magnetic
mirrors that are formed by the waves themselves. The damping is especially
effective where the angle between the wave propagation and the field lines
becomes moderately large ($\sim 20$ to $80^{\circ}$). The angle tends naturally
to increase into this range because the field in magneto-rotational winds
develops an increasingly large azimuthal component. The dissipation of the wave
energy produces heating and acceleration of the outflow. We show using
specified wind structures that this damping process can be important in both
solar-type stars and massive stars that have moderately large rotation rates.
This mechanism can play a role in coronae of young solar-type stars which are
rapidly rotating and show X-ray luminosities much larger than the sun. The
mechanism could also be important for producing the extended X-ray emitting
regions inferred to exist in massive stars of spectral type middle B and later.",0505013v5
2006-08-05,The nature of damped Lyman alpha and sub-damped Lyman alpha absorbers,"We present arguments based on the measured abundances in individual damped
Lyman alpha systems (DLAs) and sub-damped Lyman alpha systems (sub-DLAs), and
also the average abundances inferred in large samples of QSO absorption line
systems, to suggest that the amount of dust in intervening QSO absorbers is
small and is not responsible for missing many QSOs in magnitude limited QSO
surveys. While we can not totally rule out a bimodal dust distribution with a
population of very dusty, metal rich, absorbers which push the background QSOs
below the observational threshold of current optical spectroscopic studies,
based upon the current samples it appears that the metallicity in QSO absorbers
decreases with increase in H I column densities beyond 10^{19} cm^{-2}. Thus
the sub-DLA population is more metal rich than the DLAs, a trend which may
possibly extend to the non-damped Lyman limit systems (NDLLS). Based on the
recently discovered mass-metallicity relation for galaxies, we suggest that
most sub-DLAs and possibly NDLLS, are associated with massive spiral/elliptical
galaxies while most DLAs are associated with low mass galaxies. The sub-DLA
galaxies will then contribute a larger fraction of total mass (stellar and ISM)
and therefore metals, to the cosmic budget, specially at low redshifts, as
compared to the DLAs.",0608127v2
2007-02-12,The Ucsd/Keck Damped Lya Abundance Database: A Decade of High Resolution Spectroscopy,"We publish the Keck/HIRES and Keck/ESI spectra that we have obtained during
the first 10 years of Keck observatory operations. Our full sample includes 42
HIRES spectra and 39 ESI spectra along 65 unique sightlines providing abundance
measurements on ~85 damped Lya systems. The normalized data can be downloaded
from the journal or from our supporting website:
http://www.ucolick.org/~xavier/DLA/. The database includes all of the
sightlines that have been included in our papers on the chemical abundances,
kinematics, and metallicities of the damped Lya systems. This data has also
been used to argue for variations in the fine-structure constant. We present
new chemical abundance measurements for 10 damped Lya systems and a summary
table of high-resolution metallicity measurements (including values from the
literature) for 153 damped Lya systems at z>1.6. We caution, however, that this
metallicity sample (and all previous ones) is biased to higher N(HI) values
than a random sample.",0702325v1
1998-06-30,Structure and Spin Dynamics of La$_{0.85}$Sr$_{0.15}$MnO$_3$,"Neutron scattering has been used to study the structure and spin dynamics of
La$_{0.85}$Sr$_{0.15}$MnO$_3$. The magnetic structure of this system is
ferromagnetic below T_C = 235 K. We see anomalies in the Bragg peak intensities
and new superlattice peaks consistent with the onset of a spin-canted phase
below T_{CA} = 205 K, which appears to be associated with a gap at q = (0, 0,
0.5) in the spin-wave spectrum. Anomalies in the lattice parameters indicate a
concomitant lattice distortion. The long-wavelength magnetic excitations are
found to be conventional spin waves, with a gapless (< 0.02 meV) isotropic
dispersion relation $E = Dq^2$. The spin stiffness constant D has a $T^{5/2}$
dependence at low T, and the damping at small q follows $q^4T^{2}$. An
anomalously strong quasielastic component, however, develops at small wave
vector above 200 K and dominates the fluctuation spectrum as T -> T_C. At
larger q, on the other hand, the magnetic excitations become heavily damped at
low temperatures, indicating that spin waves in this regime are not eigenstates
of the system, while raising the temperature dramatically increases the
damping. The strength of the spin-wave damping also depends strongly on the
symmetry direction in the crystal. These anomalous damping effects are likely
due to the itinerant character of the $e_g$ electrons.",9806381v1
2006-06-05,Phenomenological theory of current driven exchange switching in ferromagnetic nanojunctions,"Phenomenological approach is developed in the theory of spin-valve type
ferromagnetic junctions to describe exchange switching by current flowing
perpendicular to interfaces. Forward and backward current switching effects are
described and they may be principally different in nature. Mobile electron
spins are considered as being free in all the contacting ferromagnetic layers.
Joint action of the following two current effects is investigated: the
nonequilibrium longitudinal spin-injection effective field and the transverse
spin-transfer surface torque. Dispersion relation for fluctuations is derived
and solved for a junction model having spatially localized spin transfer
torque: depth of the torque penetration into the free layer is assumed much
smaller than the total free layer thickness. Some critical value of the well
known Gilbert damping constant is established for the first time. Spin transfer
torque dominates in the instability threshold determination for small enough
damping constants, while the spin-injection effective field dominates for high
damping. Fine interplay between spin transfer torque and spin injection is
necessary to provide a hysteretic behavior of the resistance versus current
dependence. The state diagram building up shows the possibility of
non-stationary (time dependent) nonlinear states arising due to instability
development. Calculations lead to the instability rise time values of the order
of 0.1 ns. Spin wave resonance frequency spectrum softening occurs under the
current growing to the instability threshold. Magnetization fluctuations above
the threshold rise oscillating with time for low damping, but rise
aperiodically and much more rapid for high damping.",0606102v2
1999-02-01,Damping Rates and Mean Free Paths of Soft Fermion Collective Excitations in a Hot Fermion-Gauge-Scalar Theory,"We study the transport coefficients, damping rates and mean free paths of
soft fermion collective excitations in a hot fermion-gauge-scalar plasma with
the goal of understanding the main physical mechanisms that determine transport
of chirality in scenarios of non-local electroweak baryogenesis. The focus is
on identifying the different transport coefficients for the different branches
of soft collective excitations of the fermion spectrum. These branches
correspond to collective excitations with opposite ratios of chirality to
helicity and different dispersion relations. By combining results from the hard
thermal loop (HTL) resummation program with a novel mechanism of fermion
damping through heavy scalar decay, we obtain a robust description of the
different damping rates and mean free paths for the soft collective excitations
to leading order in HTL and lowest order in the Yukawa coupling. The space-time
evolution of wave packets of collective excitations unambiguously reveals the
respective mean free paths. We find that whereas both the gauge and scalar
contribution to the damping rates are different for the different branches, the
difference of mean free paths for both branches is mainly determined by the
decay of the heavy scalar into a hard fermion and a soft collective excitation.
We argue that these mechanisms are robust and are therefore relevant for
non-local scenarios of baryogenesis either in the Standard Model or extensions
thereof.",9902218v2
2002-08-29,Some notes on ideology of waves in plasmas,"Our last three papers provide an occasion to make some brief notes on
ideology of waves in plasmas and to rehabilitate Vlasov prescription to
calculate relevant logarithmically divergent integrals in the principal value
sense. In this approach asymptotical solutions of plasma oscillations are
selected according to self-consistent boundary physical conditions. Landau
damping is absent in this case by definition. Boundary electrical field
together with conditions of absence of unphysical backward and kinematical
waves define single-valued dependence of boundary distribution function on
electron velocity \vec{v} in the case of transversal waves and on the surface
break of the normal electrical field in the case of longitudinal oscillations.
We have proposed physically more justified modified iteration procedure of
collisional damping calculation and demonstrated some results of damping
decrements calculations in a low-collision electron-ion plasma. Dispersion
smearing of both longitudinal and transversal high-frequency waves, for which
the smearing decrement \delta_x is proportional to
\Delta\omega/(\omega\sqrt{\omega^2-\omega_L^2}), might be the main cause of
waves amplitude damping in collisionless plasmas imitating Landau damping.",0208098v7
2004-11-26,Open quantum systems,"The damping of the harmonic oscillator is studied in the framework of the
Lindblad theory for open quantum systems. A generalization of the fundamental
constraints on quantum mechanical diffusion coefficients which appear in the
master equation for the damped quantum oscillator is presented; the
Schr\""odinger, Heisenberg and Weyl-Wigner-Moyal representations of the Lindblad
equation are given explicitly. On the basis of these representations it is
shown that various master equations for the damped quantum oscillator used in
the literature are particular cases of the Lindblad equation and that not all
of these equations are satisfying the constraints on quantum mechanical
diffusion coefficients. The master equation is transformed into Fokker-Planck
equations for quasiprobability distributions and a comparative study is made
for the Glauber $P$ representation, the antinormal ordering $Q$ representation
and the Wigner $W$ representation. The density matrix is represented via a
generating function, which is obtained by solving a time-dependent linear
partial differential equation derived from the master equation. The damped
harmonic oscillator is applied for the description of the charge equilibration
mode observed in deep inelastic reactions. For a system consisting of two
harmonic oscillators the time dependence of expectation values, Wigner function
and Weyl operator are obtained and discussed. In addition models for the
damping of the angular momentum are studied. Using this theory to the quantum
tunneling through the nuclear barrier, besides Gamow's transitions with energy
conservation, additional transitions with energy loss, are found. When this
theory is used to the resonant atom-field interaction, new optical equations
describing the coupling through the environment are obtained.",0411189v1
2006-02-17,Damped quantum harmonic oscillator,"In the framework of the Lindblad theory for open quantum systems the damping
of the harmonic oscillator is studied. A generalization of the fundamental
constraints on quantum mechanical diffusion coefficients which appear in the
master equation for the damped quantum oscillator is presented; the
Schr\""odinger and Heisenberg representations of the Lindblad equation are given
explicitly. On the basis of these representations it is shown that various
master equations for the damped quantum oscillator used in the literature are
particular cases of the Lindblad equation and that the majority of these
equations are not satisfying the constraints on quantum mechanical diffusion
coefficients. Analytical expressions for the first two moments of coordinate
and momentum are also obtained by using the characteristic function of the
Lindblad master equation. The master equation is transformed into Fokker-Planck
equations for quasiprobability distributions. A comparative study is made for
the Glauber $P$ representation, the antinormal ordering $Q$ representation and
the Wigner $W$ representation. It is proven that the variances for the damped
harmonic oscillator found with these representations are the same. By solving
the Fokker-Planck equations in the steady state, it is shown that the
quasiprobability distributions are two-dimensional Gaussians with widths
determined by the diffusion coefficients. The density matrix is represented via
a generating function, which is obtained by solving a time-dependent linear
partial differential equation derived from the master equation. Illustrative
examples for specific initial conditions of the density matrix are provided.",0602149v1
2007-04-12,The effect of the solar corona on the attenuation of small-amplitude prominence oscillations. I. Longitudinal magnetic field,"Context. One of the typical features shown by observations of solar
prominence oscillations is that they are damped in time and that the values of
the damping times are usually between one and three times the corresponding
oscillatory period. However, the mechanism responsible for the attenuation is
still not well-known. Aims. Thermal conduction, optically thin or thick
radiation and heating are taken into account in the energy equation, and their
role on the attenuation of prominence oscillations is evaluated. Methods. The
dispersion relation for linear non-adiabatic magnetoacoustic waves is derived
considering an equilibrium made of a prominence plasma slab embedded in an
unbounded corona. The magnetic field is orientated along the direction parallel
to the slab axis and has the same strength in all regions. By solving the
dispersion relation for a fixed wavenumber, a complex oscillatory frequency is
obtained, and the period and the damping time are computed. Results. The effect
of conduction and radiation losses is different for each magnetoacoustic mode
and depends on the wavenumber. In the observed range of wavelengths the
internal slow mode is attenuated by radiation from the prominence plasma, the
fast mode by the combination of prominence radiation and coronal conduction and
the external slow mode by coronal conduction. The consideration of the external
corona is of paramount importance in the case of the fast and external slow
modes, whereas it does not affect the internal slow modes at all. Conclusions.
Non-adiabatic effects are efficient damping mechanisms for magnetoacoustic
modes, and the values of the obtained damping times are compatible with those
observed.",0704.1566v2
2007-10-01,Lyman-alpha Damping Wing Constraints on Inhomogeneous Reionization,"One well-known way to constrain the hydrogen neutral fraction, x_H, of the
high-redshift intergalactic medium (IGM) is through the shape of the red
damping wing of the Lya absorption line. We examine this method's effectiveness
in light of recent models showing that the IGM neutral fraction is highly
inhomogeneous on large scales during reionization. Using both analytic models
and ""semi-numeric"" simulations, we show that the ""picket-fence"" absorption
typical in reionization models introduces both scatter and a systematic bias to
the measurement of x_H. In particular, we show that simple fits to the damping
wing tend to overestimate the true neutral fraction in a partially ionized
universe, with a fractional error of ~ 30% near the middle of reionization.
This bias is generic to any inhomogeneous model. However, the bias is reduced
and can even underestimate x_H if the observational sample only probes a subset
of the entire halo population, such as quasars with large HII regions. We also
find that the damping wing absorption profile is generally steeper than one
would naively expect in a homogeneously ionized universe. The profile steepens
and the sightline-to-sightline scatter increases as reionization progresses. Of
course, the bias and scatter also depend on x_H and so can, at least in
principle, be used to constrain it. Damping wing constraints must therefore be
interpreted by comparison to theoretical models of inhomogeneous reionization.",0710.0371v1
2008-02-11,Eccentricity of masing disks in Active Galactic Nuclei,"Observations of Keplerian disks of masers in NCG 4258 and other Seyfert
galaxies can be used to obtain geometric distance estimates and derive the
Hubble constant. The ultimate precision of such measurements could be limited
by uncertainties in the disk geometry. Using a time-dependent linear theory
model, we study the evolution of a thin initially eccentric disk under
conditions appropriate to sub-pc scales in Active Galactic Nuclei. The
evolution is controlled by a combination of differential precession driven by
the disk potential and propagating eccentricity waves that are damped by
viscosity. A simple estimate yields a circularization timescale of
approximately 10 Myr at 0.1 pc. Numerical solutions for the eccentricity
evolution confirm that damping commences on this timescale, but show that the
subsequent decay rate of the eccentricity depends upon the uncertain strength
of viscous damping of eccentricity. If eccentricity waves are important further
decay of the eccentricity can be slow, with full circularization requiring up
to 50 Myr for disks at radii of 0.1 pc to 0.2 pc. Observationally, this implies
that it is plausible that enough time has elapsed for the eccentricity of
masing disks to have been substantially damped, but that it may not be
justified to assume vanishing eccentricity. We predict that during the damping
phase the pericenter of the eccentric orbits describes a moderately tightly
wound spiral with radius.",0802.1524v1
2008-02-20,The Effect of Charon's Tidal Damping on the Orbits of Pluto's Three Moons,"Pluto's recently discovered minor moons, Nix and Hydra, have almost circular
orbits, and are nearly coplanar with Charon, Pluto's major moon. This is
surprising because tidal interactions with Pluto are too weak to damp their
eccentricities. We consider an alternative possibility: that Nix and Hydra
circularize their orbits by exciting Charon's eccentricity via secular
interactions, and Charon in turn damps its own eccentricity by tidal
interaction with Pluto. The timescale for this process can be less than the age
of the Solar System, for plausible tidal parameters and moon masses. However,
as we show numerically and analytically, the effects of the 2:1 and 3:1
resonant forcing terms between Nix and Charon complicate this picture. In the
presence of Charon's tidal damping, the 2:1 term forces Nix to migrate outward
and the 3:1 term changes the eccentricity damping rate, sometimes leading to
eccentricity growth. We conclude that this mechanism probably does not explain
Nix and Hydra's current orbits. Instead, we suggest that they were formed
in-situ with low eccentricities.
  We also show that an upper limit on Nix's migration speed sets a lower limit
on Pluto-Charon's tidal circularization timescale of >10^5 yrs. Moreover,
Hydra's observed proper eccentricity may be explained by the 3:2 forcing by
Nix.",0802.2939v1
2008-03-18,Non-adiabatic magnetohydrodynamic waves in a cylindrical prominence thread with mass flow,"High-resolution observations show that oscillations and waves in prominence
threads are common and that they are attenuated in a few periods. In addition,
observers have also reported the presence of material flows in such prominence
fine-structures. Here we investigate the time damping of non-leaky oscillations
supported by a homogeneous cylindrical prominence thread embedded in an
unbounded corona and with a steady mass flow. Thermal conduction and radiative
losses are taken into account as damping mechanisms, and the effect of these
non-ideal effects and the steady flow on the attenuation of oscillations is
assessed. We solve the general dispersion relation for linear, non-adiabatic
magnetoacoustic and thermal waves supported by the model, and find that slow
and thermal modes are efficiently attenuated by non-adiabatic mechanisms. On
the contrary, fast kink modes are much less affected and their damping times
are much larger than those observed. The presence of flow has no effect on the
damping of slow and thermal waves, whereas fast kink waves are more (less)
attenuated when they propagate parallel (anti-parallel) to the flow direction.
Although the presence of steady mass flows improves the efficiency of
non-adiabatic mechanisms on the attenuation of transverse, kink oscillations
for parallel propagation to the flow, its effect is still not enough to obtain
damping times compatible with observations.",0803.2600v2
2008-05-22,Intrinsic and non-local Gilbert damping in polycrystalline nickel studied by Ti:Sapphire laser fs spectroscopy,"The use of femtosecond laser pulses generated by a Ti:Sapphire laser system
allows us to gain an insight into the magnetization dynamics on time scales
from sub-picosecond up to 1 ns directly in the time domain. This experimental
technique is used to excite a polycrystalline nickel (Ni) film optically and
probe the dynamics afterwards. Different spin wave modes (the Kittel mode,
perpendicular standing spin-wave modes (PSSW) and dipolar spin-wave modes
(Damon-Eshbach modes)) are identified as the Ni thickness is increased. The
Kittel mode allows determination of the Gilbert damping parameter alpha
extracted from the magnetization relaxation time tau_alpha. The non-local
damping by spin currents emitted into a non-magnetic metallic layer of vanadium
(V), palladium (Pd) and the rare earth dysprosium (Dy) are studied for
wedge-shaped Ni films 1 nm-30 nm. The damping parameter increases from
alpha=0.045 intrinsic for nickel to alpha>0.10 for the heavy materials, such as
Pd and Dy, for the thinnest Ni films below 10 nm thickness. Also, for the
thinnest reference Ni film thickness, an increased magnetic damping below 4 nm
is observed. The origin of this increase is discussed within the framework of
line broadening by locally different precessional frequencies within the laser
spot region.",0805.3495v1
2009-02-26,Viscous propagation of mass flow variability in accretion discs,"We study mass flow rate through a disc resulting from a varying mass supply
rate. Variable mass supply rate occurs, e.g., during disc state transitions,
and in interacting eccentric binaries. It is, however, damped by the viscosity
of the disc. Here, we calculate this damping in detail. We derive an analytical
description of the propagation of the flow rate using the solution of
Lynden-Bell & Pringle, in which the disc is assumed to extend to infinity. In
particular, we derive the accretion-rate Green's function, and its Fourier
transform, which gives the fractional damping at a given variability frequency.
We then compare this model to that of a finite disc with the mass supply at its
outer edge. We find significant differences with respect to the infinite disc
solution, which we find to overestimate the viscous damping. In particular, the
asymptotic form of the Green's function is power-law for the infinite disc and
exponential for the finite one. We then find a simple fitting form for the
latter, and also calculate its Fourier transform. In general, the damping
becomes very strong when the viscous time at the outer edge of the disc becomes
longer than the modulation time scale. We apply our results to a number of
astrophysical systems. We find the effect is much stronger in low-mass X-ray
binaries, where the disc size is comparable to that of the Roche lobe, than in
high-mass binaries, where the wind-fed disc can have a much smaller size.",0902.4530v2
2010-04-09,Oscillations of weakly viscous conducting liquid drops in a strong magnetic field,"We analyse small-amplitude oscillations of a weakly viscous electrically
conducting liquid drop in a strong uniform DC magnetic field. An asymptotic
solution is obtained showing that the magnetic field does not affect the shape
eigenmodes, which remain the spherical harmonics as in the non-magnetic case.
Strong magnetic field, however, constrains the liquid flow associated with the
oscillations and, thus, reduces the oscillation frequencies by increasing
effective inertia of the liquid. In such a field, liquid oscillates in a
two-dimensional (2D) way as solid columns aligned with the field. Two types of
oscillations are possible: longitudinal and transversal to the field. Such
oscillations are weakly damped by a strong magnetic field - the stronger the
field, the weaker the damping, except for the axisymmetric transversal and
inherently 2D modes. The former are overdamped because of being incompatible
with the incompressibility constraint, whereas the latter are not affected at
all because of being naturally invariant along the field. Since the magnetic
damping for all other modes decreases inversely with the square of the field
strength, viscous damping may become important in a sufficiently strong
magnetic field. The viscous damping is found analytically by a simple energy
dissipation approach which is shown for the longitudinal modes to be equivalent
to a much more complicated eigenvalue perturbation technique. This study
provides a theoretical basis for the development of new measurement methods of
surface tension, viscosity and the electrical conductivity of liquid metals
using the oscillating drop technique in a strong superimposed DC magnetic
field.",1004.1548v2
2011-02-03,Damping of Electron Density Structures and Implications for Interstellar Scintillation,"The forms of electron density structures in kinetic Alfven wave turbulence
are studied in connection with scintillation. The focus is on small scales $L
\sim 10^8-10^{10}$ cm where the Kinetic Alfv\'en wave (KAW) regime is active in
the interstellar medium. MHD turbulence converts to a KAW cascade, starting at
10 times the ion gyroradius and continuing to smaller scales. These scales are
inferred to dominate scintillation in the theory of Boldyrev et al. From
numerical solutions of a decaying kinetic Alfv\'en wave turbulence model,
structure morphology reveals two types of localized structures, filaments and
sheets, and shows that they arise in different regimes of resistive and
diffusive damping. Minimal resistive damping yields localized current filaments
that form out of Gaussian-distributed initial conditions. When resistive
damping is large relative to diffusive damping, sheet-like structures form. In
the filamentary regime, each filament is associated with a non-localized
magnetic and density structure, circularly symmetric in cross section. Density
and magnetic fields have Gaussian statistics (as inferred from Gaussian-valued
kurtosis) while density gradients are strongly non-Gaussian, more so than
current. This enhancement of non-Gaussian statistics in a derivative field is
expected since gradient operations enhance small-scale fluctuations. The
enhancement of density gradient kurtosis over current kurtosis is not obvious,
yet it suggests that modest fluctuation levels in electron density may yield
large scintillation events during pulsar signal propagation in the interstellar
medium. In the sheet regime the same statistical observations hold, despite the
absence of localized filamentary structures. Probability density functions are
constructed from statistical ensembles in both regimes, showing clear formation
of long, highly non-Gaussian tails.",1102.0810v2
2011-09-28,"Different dimensionality trends in the Landau damping of magnons in iron, cobalt and nickel: time dependent density functional study","We study the Landau damping of ferromagnetic magnons in Fe, Co, and Ni as the
dimensionality of the system is reduced from three to two. We resort to the
\textit{ab initio} linear response time dependent density functional theory in
the adiabatic local spin density approximation. The numerical scheme is based
on the Korringa-Kohn-Rostoker Green's function method. The key points of the
theoretical approach and the implementation are discussed. We investigate the
transition metals in three different forms: bulk phases, free-standing thin
films and thin films supported on a nonmagnetic substrate. We demonstrate that
the dimensionality trends in Fe and Ni are opposite: in Fe the transition from
bulk bcc crystal to Fe/Cu(100) film reduces the damping whereas in Ni/Cu(100)
film the attenuation increases compared to bulk fcc Ni. In Co, the strength of
the damping depends relatively weakly on the sample dimensionality. We explain
the difference in the trends on the basis of the underlying electronic
structure. The influence of the substrate on the spin-wave damping is analyzed
by employing Landau maps representing wave-vector resolved spectral density of
the Stoner excitations.",1109.6217v2
2011-10-06,Dissipative and conservative nonlinearity in carbon nanotube and graphene mechanical resonators,"Graphene and carbon nanotubes represent the ultimate size limit of one and
two-dimensional nanoelectromechanical resonators. Because of their reduced
dimensionality, graphene and carbon nanotubes display unusual mechanical
behavior; in particular, their dynamics is highly nonlinear. Here, we review
several types of nonlinear behavior in resonators made from nanotubes and
graphene. We first discuss an unprecedented scenario where damping is described
by a nonlinear force. This scenario is supported by several experimental facts:
(i) the quality factor varies with the amplitude of the motion as a power law
whose exponent coincides with the value predicted by the nonlinear damping
model, (ii) hysteretic behavior (of the motional amplitude as a function of
driving frequency) is absent in some of our resonators even for large driving
forces, as expected when nonlinear damping forces are large, and (iii) when we
quantify the linear damping force (by performing parametric excitation
measurements) we find that it is significantly smaller than the nonlinear
damping force. We then review parametric excitation measurements, an
alternative actuation method which is based on nonlinear dynamics. Finally, we
discuss experiments where the mechanical motion is coupled to electron
transport through a nanotube. The coupling can be made so strong that the
associated force acting on the nanotube becomes highly nonlinear with
displacement and velocity. Overall, graphene and nanotube resonators hold
promise for future studies on classical and quantum nonlinear dynamics.",1110.1234v1
2012-06-02,Slow Mode Oscillations and Damping of Hot Solar Coronal Loops,"The effect of temperature inhomogeneity on the periods, their ratios
(fundamental vs. first overtone), and the damping times of the standing slow
modes in gravitationally stratified solar coronal loops are studied. The
effects of optically thin radiation, compressive viscosity, and thermal
conduction are considered. The linearized one-dimensional magnetohydrodynamic
(MHD) equations (under low-$\beta$ condition) were reduced to a fourth--order
ordinary differential equation for the perturbed velocity. The numerical
results indicate that the periods of non-isothermal loops (i.e. temperature
increases from the loop base to apex) are smaller compared to those of
isothermal loops. In the presence of radiation, viscosity, and thermal
conduction, an increase in the temperature gradient is followed by a monotonic
decrease in the periods (compared with the isothermal case), while the period
ratio turns out to be a sensitive function of the gradient of the temperature
and the loop lengths. We verify that radiative dissipation is not a main
cooling mechanism of both isothermal and non-isothermal hot coronal loops and
has a small effect on the periods. Thermal conduction and compressive viscosity
are primary mechanisms in the damping of slow modes of the hot coronal loops.
The periods and damping times in the presence of compressive viscosity and/or
thermal conduction dissipation are consistent with the observed data in
specific cases. By tuning the dissipation parameters, the periods and the
damping times could be made consistent with the observations in more general
cases.",1206.0366v1
2012-09-15,Damped kink oscillations of flowing prominence threads,"Transverse oscillations of thin threads in solar prominences are frequently
reported in high-resolution observations. Two typical features of the
observations are that the oscillations are damped in time and that simultaneous
mass flows along the threads are detected. Flows cause the dense threads to
move along the prominence magnetic structure while the threads are oscillating.
The oscillations have been interpreted in terms of standing magnetohydrodynamic
(MHD) kink waves of the magnetic flux tubes which support the threads. The
damping is most likely due to resonant absorption caused by plasma
inhomogeneity. The technique of seismology uses the observations combined with
MHD wave theory to estimate prominence physical parameters. This paper presents
a theoretical study of the joint effect of flow and resonant absorption on the
amplitude of standing kink waves in prominence threads. We find that flow and
resonant absorption can either be competing effects on the amplitude or both
can contribute to damp the oscillations depending on the instantaneous position
of the thread within the prominence magnetic structure. The amplitude profile
deviates from the classic exponential profile of resonantly damped kink waves
in static flux tubes. Flow also introduces a progressive shift of the
oscillation period compared to the static case, although this effect is in
general of minor importance. We test the robustness of seismological estimates
by using synthetic data aiming to mimic real observations. The effect of the
thread flow can significantly affect the estimation of the transverse
inhomogeneity length scale. The presence of random background noise adds
uncertainty to this estimation. Caution needs to be paid to the seismological
estimates that do not take the influence of flow into account.",1209.3382v1
2013-04-13,Parametric survey of longitudinal prominence oscillation simulations,"It is found that both microflare-sized impulsive heating at one leg of the
loop and a suddenly imposed velocity perturbation can propel the prominence to
oscillate along the magnetic dip. An extensive parameter survey results in a
scaling law, showing that the period of the oscillation, which weakly depends
on the length and height of the prominence, and the amplitude of the
perturbations, scales with $\sqrt{R/g_\odot}$, where $R$ represents the
curvature radius of the dip, and $g_\odot$ is the gravitational acceleration of
the Sun. This is consistent with the linear theory of a pendulum, which implies
that the field-aligned component of gravity is the main restoring force for the
prominence longitudinal oscillations, as confirmed by the force analysis.
However, the gas pressure gradient becomes non-negligible for short
prominences. The oscillation damps with time in the presence of non-adiabatic
processes. Compared to heat conduction, the radiative cooling is the dominant
factor leading to the damping. A scaling law for the damping timescale is
derived, i.e., $\tau\sim l^{1.63} D^{0.66}w^{-1.21}v_{0}^{-0.30}$, showing
strong dependence on the prominence length $l$, the geometry of the magnetic
dip (characterized by the depth $D$ and the width $w$), and the velocity
perturbation amplitude $v_0$. The larger the amplitude, the faster the
oscillation damps. It is also found that mass drainage significantly reduces
the damping timescale when the perturbation is too strong.",1304.3798v1
2013-06-08,Observation of a Berry phase anti-damping spin-orbit torque,"Recent observations of current-induced magnetization switching at
ferromagnet/normal-conductor interfaces have important consequences for future
magnetic memory technology. In one interpretation, the switching originates
from carriers with spin-dependent scattering giving rise to a relativistic
anti-damping spin-orbit torque (SOT) in structures with broken space-inversion
symmetry. The alternative interpretation combines the relativistic spin Hall
effect (SHE), making the normal-conductor an injector of a spin-current, with
the non-relativistic spin-transfer torque (STT) in the ferromagnet. Remarkably,
the SHE in these experiments originates from the Berry phase effect in the band
structure of a clean crystal and the anti-damping STT is also based on a
disorder-independent transfer of spin from carriers to magnetization. Here we
report the observation of an anti-damping SOT stemming from an analogous Berry
phase effect to the SHE. The SOT alone can therefore induce magnetization
dynamics based on a scattering-independent principle. The ferromagnetic
semiconductor (Ga,Mn)As we use has a broken space-inversion symmetry in the
crystal. This allows us to consider a bare ferromagnetic element which
eliminates by design any SHE related contribution to the spin torque. We
provide an intuitive picture of the Berry phase origin of the anti-damping SOT
and a microscopic modeling of measured data.",1306.1893v1
2014-11-24,Damping of liquid sloshing by foams,"When a container is set in motion, the free surface of the liquid starts to
oscillate or slosh. Such effects can be observed when a glass of water is
handled carelessly and the fluid sloshes or even spills over the rims of the
container. However, beer does not slosh as readily as water, which suggests
that foam could be used to damp sloshing. In this work, we study experimentally
the effect on sloshing of a liquid foam placed on top of a liquid bath. We
generate a monodisperse two-dimensional liquid foam in a rectangular container
and track the motion of the foam. The influence of the foam on the sloshing
dynamics is experimentally characterized: only a few layers of bubbles are
sufficient to significantly damp the oscillations. We rationalize our
experimental findings with a model that describes the foam contribution to the
damping coefficient through viscous dissipation on the walls of the container.
Then we extend our study to confined three-dimensional liquid foam and observe
that the behavior of 2D and confined 3D systems are very similar. Thus we
conclude that only the bubbles close to the walls have a significant impact on
the dissipation of energy. The possibility to damp liquid sloshing using foam
is promising in numerous industrial applications such as the transport of
liquefied gas in tankers or for propellants in rocket engines.",1411.6542v2
2015-04-16,Attenuation of short strongly nonlinear stress pulses in dissipative granular chains,"Attenuation of short, strongly nonlinear stress pulses in chains of spheres
and cylinders was investigated experimentally and numerically for two ratios of
their masses keeping their contacts identical. The chain with mass ratio 0.98
supports solitary waves and another one (with mass ratio 0.55) supports
nonstationary pulses which preserve their identity only on relatively short
distances, but attenuate on longer distances because of radiation of small
amplitude tails generated by oscillating small mass particles. Pulse
attenuation in experiments in the chain with mass ratio 0.55 was faster at the
same number of the particles from the entrance than in the chain with mass
ratio 0.98. It is in quantitative agreement with results of numerical
calculations with effective damping coefficient 6 kg/s. This level of damping
was critical for eliminating the gap openings between particles in the system
with mass ratio 0.55 present at lower or no damping. However with increase of
dissipation numerical results show that the chain with mass ratio 0.98 provides
faster attenuation than chain with mass ratio 0.55 due to the fact that the
former system supports the narrower pulse with the larger difference between
velocities of neighboring particles. The investigated chains demonstrated
different wave structure at zero dissipation and at intermediate damping
coefficients and the similar behavior at large damping.",1504.04344v1
2015-04-17,Chiral damping of magnetic domain walls,"Structural symmetry breaking in magnetic materials is responsible for a
variety of outstanding physical phenomena. Examples range from the existence of
multiferroics, to current induced spin orbit torques (SOT) and the formation of
topological magnetic structures. In this letter we bring into light a novel
effect of the structural inversion asymmetry (SIA): a chiral damping mechanism.
This phenomenon is evidenced by measuring the field driven domain wall (DW)
motion in perpendicularly magnetized asymmetric Pt/Co/Pt trilayers. The
difficulty in evidencing the chiral damping is that the ensuing DW dynamics
exhibit identical spatial symmetry to those expected from the
Dzyaloshinskii-Moriya interaction (DMI). Despite this fundamental resemblance,
the two scenarios are differentiated by their time reversal properties: while
DMI is a conservative effect that can be modeled by an effective field, the
chiral damping is purely dissipative and has no influence on the equilibrium
magnetic texture. When the DW motion is modulated by an in-plane magnetic
field, it reveals the structure of the internal fields experienced by the DWs,
allowing to distinguish the physical mechanism. The observation of the chiral
damping, not only enriches the spectrum of physical phenomena engendered by the
SIA, but since it can coexists with DMI it is essential for conceiving DW and
skyrmion devices.",1504.04411v1
2015-06-18,The absence of intraband scattering in a consistent theory of Gilbert damping in metallic ferromagnets,"Damping of magnetization dynamics in a ferromagnetic metal is usually
characterized by the Gilbert parameter alpha. Recent calculations of this
quantity, using a formula due to Kambersky, find that it is infinite for a
perfect crystal owing to an intraband scattering term which is of third order
in the spin-orbit parameter xi This surprising result conflicts with recent
work by Costa and Muniz who study damping numerically by direct calculation of
the dynamical transverse spin susceptibility in the presence of spin-orbit
coupling. We resolve this inconsistency by following the Costa-Muniz approach
for a slightly simplified model where it is possible to calculate alpha
analytically. We show that to second order in the spin-orbit parameter xi one
retrieves the Kambersky result for alpha, but to higher order one does not
obtain any divergent intraband terms. The present work goes beyond that of
Costa and Muniz by pointing out the necessity of including the effect of
long-range Coulomb interaction in calculating damping for large xi. A direct
derivation of the Kambersky formula is given which shows clearly the
restriction of its validity to second order in xi so that no intraband
scattering terms appear. This restriction has an important effect on the
damping over a substantial range of impurity content and temperature. The
experimental situation is discussed.",1506.05622v2
2015-07-28,Spatial damping of propagating sausage waves in coronal cylinders,"Sausage modes are important in coronal seismology. Spatially damped
propagating sausage waves were recently observed in the solar atmosphere. We
examine how wave leakage influences the spatial damping of sausage waves
propagating along coronal structures modeled by a cylindrical density
enhancement embedded in a uniform magnetic field. Working in the framework of
cold magnetohydrodynamics, we solve the dispersion relation (DR) governing
sausage waves for complex-valued longitudinal wavenumber $k$ at given real
angular frequencies $\omega$. For validation purposes, we also provide
analytical approximations to the DR in the low-frequency limit and in the
vicinity of $\omega_{\rm c}$, the critical angular frequency separating trapped
from leaky waves. In contrast to the standing case, propagating sausage waves
are allowed for $\omega$ much lower than $\omega_{\rm c}$. However, while able
to direct their energy upwards, these low-frequency waves are subject to
substantial spatial attenuation. The spatial damping length shows little
dependence on the density contrast between the cylinder and its surroundings,
and depends only weakly on frequency. This spatial damping length is of the
order of the cylinder radius for $\omega \lesssim 1.5 v_{\rm Ai}/a$, where $a$
and $v_{\rm Ai}$ are the cylinder radius and the Alfv\'en speed in the
cylinder, respectively. We conclude that if a coronal cylinder is perturbed by
symmetric boundary drivers (e.g., granular motions) with a broadband spectrum,
wave leakage efficiently filters out the low-frequency components.",1507.07724v1
2015-10-19,On the branching of the quasinormal resonances of near-extremal Kerr black holes,"It has recently been shown by Yang. et. al. [Phys. Rev. D {\bf 87}, 041502(R)
(2013)] that rotating Kerr black holes are characterized by two distinct sets
of quasinormal resonances. These two families of quasinormal resonances display
qualitatively different asymptotic behaviors in the extremal ($a/M\to 1$)
black-hole limit: The zero-damping modes (ZDMs) are characterized by relaxation
times which tend to infinity in the extremal black-hole limit ($\Im\omega\to 0$
as $a/M\to 1$), whereas the damped modes (DMs) are characterized by non-zero
damping rates ($\Im\omega\to$ finite-values as $a/M\to 1$). In this paper we
refute the claim made by Yang et. al. that co-rotating DMs of near-extremal
black holes are restricted to the limited range $0\leq
\mu\lesssim\mu_{\text{c}}\approx 0.74$, where $\mu\equiv m/l$ is the
dimensionless ratio between the azimuthal harmonic index $m$ and the spheroidal
harmonic index $l$ of the perturbation mode. In particular, we use an
analytical formula originally derived by Detweiler in order to prove the
existence of DMs (damped quasinormal resonances which are characterized by
finite $\Im\omega$ values in the $a/M\to 1$ limit) of near-extremal black holes
in the $\mu>\mu_{\text{c}}$ regime, the regime which was claimed by Yang et.
al. not to contain damped modes. We show that these co-rotating DMs (in the
regime $\mu>\mu_{\text{c}}$) are expected to characterize the resonance spectra
of rapidly-rotating (near-extremal) black holes with $a/M\gtrsim 1-10^{-9}$.",1510.05604v1
2016-02-16,Damping and power spectra of quasi-periodic intensity disturbances above a solar polar coronal hole,"We study intensity disturbances above a solar polar coronal hole seen in the
AIA 171 \AA\ and 193 \AA\ passbands, aiming to provide more insights into their
physical nature. The damping and power spectra of the intensity disturbances
with frequencies from 0.07 mHz to 10.5 mHz are investigated. The damping of the
intensity disturbances tends to be stronger at lower frequencies, and their
damping behavior below 980"" (for comparison, the limb is at 945"") is different
from what happens above. No significant difference is found between the damping
of the intensity disturbances in the AIA 171 \AA\ and that in the AIA 193 \AA.
The indices of the power spectra of the intensity disturbances are found to be
slightly smaller in the AIA 171 \AA\ than in the AIA 193 \AA, but the
difference is within one sigma deviation. An additional enhanced component is
present in the power spectra in a period range of 8--40 minutes at lower
heights. While the power spectra of spicule is highly correlated with its
associated intensity disturbance, it suggests that the power spectra of the
intensity disturbances might be a mixture of spicules and wave activities. We
suggest that each intensity disturbance in the polar coronal hole is possibly a
series of independent slow magnetoacoustic waves triggered by spicular
activities.",1602.04883v1
2016-04-20,Nonlinear wave damping due to multi-plasmon resonances,"For short wavelengths, it is well known that the linearized Wigner-Moyal
equation predicts wave damping due to wave-particle interaction, where the
resonant velocity shifted from the phase velocity by a velocity $v_q = \hbar
k/2m$. Here $\hbar$ is the reduced Planck constant, $k$ is the wavenumber and
$m$ is the electron mass. Going beyond linear theory, we find additional
resonances with velocity shifts $n v_q$, $n = 2, 3, \ldots$, giving rise to a
new wave-damping mechanism that we term \emph{multi-plasmon damping}, as it can
be seen as the simultaneous absorption (or emission) of multiple plasmon
quanta. Naturally this wave damping is not present in classical plasmas. For a
temperature well below the Fermi temperature, if the linear ($n = 1$) resonant
velocity is outside the Fermi sphere, the number of linearly resonant particles
is exponentially small, while the multi-plasmon resonances can be located in
the bulk of the distribution. We derive sets of evolution equations for the
case of two-plasmon and three-plasmon resonances for Langmuir waves in the
simplest case of a fully degenerate plasma. By solving these equations
numerically for a range of wave-numbers we find the corresponding damping
rates, and we compare them to results from linear theory to estimate the
applicability. Finally, we discuss the effects due to a finite temperature.",1604.05983v2
2016-07-06,Measuring Collisionless Damping in Heliospheric Plasmas using Field-Particle Correlations,"An innovative field-particle correlation technique is proposed that uses
single-point measurements of the electromagnetic fields and particle velocity
distribution functions to investigate the net transfer of energy from fields to
particles associated with the collisionless damping of turbulent fluctuations
in weakly collisional plasmas, such as the solar wind. In addition to providing
a direct estimate of the local rate of energy transfer between fields and
particles, it provides vital new information about the distribution of that
energy transfer in velocity space. This velocity-space signature can
potentially be used to identify the dominant collisionless mechanism
responsible for the damping of turbulent fluctuations in the solar wind. The
application of this novel field-particle correlation technique is illustrated
using the simplified case of the Landau damping of Langmuir waves in an
electrostatic 1D-1V Vlasov-Poisson plasma, showing that the procedure both
estimates the local rate of energy transfer from the electrostatic field to the
electrons and indicates the resonant nature of this interaction. Modifications
of the technique to enable single-point spacecraft measurements of fields and
particles to diagnose the collisionless damping of turbulent fluctuations in
the solar wind are discussed, yielding a method with the potential to transform
our ability to maximize the scientific return from current and upcoming
spacecraft missions, such as the Magnetospheric Multiscale (MMS) and Solar
Probe Plus missions.",1607.01738v1
2016-07-22,Excitation of nonlinear ion acoustic waves in CH plasmas,"Excitation of nonlinear ion acoustic wave (IAW) by an external electric field
is demonstrated by Vlasov simulation. The frequency calculated by the
dispersion relation with no damping is verified much closer to the resonance
frequency of the small-amplitude nonlinear IAW than that calculated by the
linear dispersion relation. When the wave number $ k\lambda_{De} $ increases,
the linear Landau damping of the fast mode (its phase velocity is greater than
any ion's thermal velocity) increases obviously in the region of $ T_i/T_e <
0.2 $ in which the fast mode is weakly damped mode. As a result, the deviation
between the frequency calculated by the linear dispersion relation and that by
the dispersion relation with no damping becomes larger with $k\lambda_{De}$
increasing. When $k\lambda_{De}$ is not large, such as $k\lambda_{De}=0.1, 0.3,
0.5$, the nonlinear IAW can be excited by the driver with the linear frequency
of the modes. However, when $k\lambda_{De}$ is large, such as
$k\lambda_{De}=0.7$, the linear frequency can not be applied to exciting the
nonlinear IAW, while the frequency calculated by the dispersion relation with
no damping can be applied to exciting the nonlinear IAW.",1607.06598v1
2017-03-01,The Plastic Scintillator Detector at DAMPE,"he DArk Matter Particle Explorer (DAMPE) is a general purposed
satellite-borne high energy $\gamma-$ray and cosmic ray detector, and among the
scientific objectives of DAMPE are the searches for the origin of cosmic rays
and an understanding of Dark Matter particles. As one of the four detectors in
DAMPE, the Plastic Scintillator Detector (PSD) plays an important role in the
particle charge measurement and the photons/electrons separation. The PSD has
82 modules, each consists of a long organic plastic scintillator bar and two
PMTs at both ends for readout, in two layers and covers an overall active area
larger than 82 cm $\times$ 82 cm. It can identify the charge states for
relativistic ions from H to Fe, and the detector efficiency for Z=1 particles
can reach 0.9999. The PSD has been successfully launched with DAMPE on Dec. 17,
2015. In this paper, the design, the assembly, the qualification tests of the
PSD and some of the performance measured on the ground have been described in
detail.",1703.00098v1
2017-03-22,Observation of a strong coupling effect on electron-ion collisions in ultracold plasmas,"Ultracold plasmas (UCP) provide a well-controlled system for studying
multiple aspects in plasma physics that include collisions and strong coupling
effects. By applying a short electric field pulse to a UCP, a plasma electron
center-of-mass (CM) oscillation can be initiated. In accessible parameter
ranges, the damping rate of this oscillation is determined by the electron-ion
collision rate. We performed measurements of the oscillation damping rate with
such parameters and compared the measured rates to both a molecular dynamic
(MD) simulation that includes strong coupling effects and to Monte-Carlo
collisional operator simulation designed to predict the damping rate including
only weak coupling considerations. We found agreement between experimentally
measured damping rate and the MD result. This agreement did require including
the influence of a previously unreported UCP heating mechanism whereby the
presence of a DC electric field during ionization increased the electron
temperature, but estimations and simulations indicate that such a heating
mechanism should be present for our parameters. The measured damping rate at
our coldest electron temperature conditions was much faster than the weak
coupling prediction obtained from the Monte-Carlo operator simulation, which
indicates the presence of significant strong coupling influence. The density
averaged electron strong coupling parameter $\Gamma$ measured at our coldest
electron temperature conditions was 0.35.",1703.07852v2
2017-07-21,Spatially Localized Particle Energization by Landau Damping in Current Sheets Produced by Strong Alfven Wave Collisions,"Understanding the removal of energy from turbulent fluctuations in a
magnetized plasma and the consequent energization of the constituent plasma
particles is a major goal of heliophysics and astrophysics. Previous work has
shown that nonlinear interactions among counterpropagating Alfven waves---or
Alfven wave collisions---are the fundamental building block of astrophysical
plasma turbulence and naturally generate current sheets in the strongly
nonlinear limit. A nonlinear gyrokinetic simulation of a strong Alfven wave
collision is used to examine the damping of the electromagnetic fluctuations
and the associated energization of particles that occurs in self-consistently
generated current sheets. A simple model explains the flow of energy due to the
collisionless damping and the associated particle energization, as well as the
subsequent thermalization of the particle energy by collisions. The net
particle energization by the parallel electric field is shown to be spatially
intermittent, and the nonlinear evolution is essential in enabling that spatial
non-uniformity. Using the recently developed field-particle correlation
technique, we show that particles resonant with the Alfven waves in the
simulation dominate the energy transfer, demonstrating conclusively that Landau
damping plays a key role in the spatially intermittent damping of the
electromagnetic fluctuations and consequent energization of the particles in
this strongly nonlinear simulation.",1708.00757v1
2019-05-14,Fractional damping through restricted calculus of variations,"We deliver a novel approach towards the variational description of Lagrangian
mechanical systems subject to fractional damping by establishing a restricted
Hamilton's principle. Fractional damping is a particular instance of non-local
(in time) damping, which is ubiquitous in mechanical engineering applications.
The restricted Hamilton's principle relies on including fractional derivatives
to the state space, the doubling of curves (which implies an extra mirror
system) and the restriction of the class of varied curves. We will obtain the
correct dynamics, and will show rigorously that the extra mirror dynamics is
nothing but the main one in reversed time; thus, the restricted Hamilton's
principle is not adding extra physics to the original system. The price to pay,
on the other hand, is that the fractional damped dynamics is only a sufficient
condition for the extremals of the action. In addition, we proceed to
discretise the new principle. This discretisation provides a set of numerical
integrators for the continuous dynamics that we denote Fractional Variational
Integrators (FVIs). The discrete dynamics is obtained upon the same
ingredients, say doubling of discrete curves and restriction of the discrete
variations. We display the performance of the FVIs, which have local truncation
order 1, in two examples. As other integrators with variational origin, for
instance those generated by the discrete Lagrange-d'Alembert principle, they
show a superior performance tracking the dissipative energy, in opposition to
direct (order 1) discretisations of the dissipative equations, such as explicit
and implicit Euler schemes.",1905.05608v1
2019-05-22,Ultra-low magnetic damping in Co 2 Mn-based Heusler compounds: promising materials for spintronic,"The prediction of ultra-low magnetic damping in Co 2 MnZ Heusler half-metal
thin-film magnets is explored in this study and the damping response is shown
to be linked to the underlying electronic properties. By substituting the Z
elements in high crystalline quality films (Co 2 MnZ with Z=Si, Ge, Sn, Al, Ga,
Sb), electronic properties such as the minority spin band gap, Fermi energy
position in the gap and spin polarization can be tuned and the consequence on
magnetization dynamics analyzed. The experimental results allow us to directly
explore the interplay of spin polarization, spin gap, Fermi energy position and
the magnetic damping obtained in these films, together with ab initio
calculation predictions. The ultra-low magnetic damping coefficients measured
in the range 4.1 10-4-9 10-4 for Co 2 MnSi, Ge, Sn, Sb are the lowest values
obtained on a conductive layer and offers a clear experimental demonstration of
theoretical predictions on Half-Metal Magnetic Heusler compounds and a pathway
for future materials design.",1905.08987v1
2013-08-20,Stringent constraints on the H I spin temperature in two z > 3 Damped Lyman-alpha systems from redshifted 21 cm absorption studies,"Physical properties of Damped Lyman-alpha absorbers and their evolution are
closely related to galaxy formation and evolution theories, and have important
cosmological implications. H I 21 cm absorption study is one useful way of
measuring the temperature of these systems. In this work, very strong
constraints on the temperature of two Damped Lyman-alpha absorbers at z > 3 are
derived from low radio frequency observations. The H I spin temperature is
found to be greater than 2000 K for both the absorbers. The high spin
temperature of these high-redshift systems is in agreement with the trend found
in a compilation of temperatures for other Damped Lyman-alpha absorbers. We
also argue that the temperature - metallicity relation, reported earlier in the
literature, is unlikely to be a spurious line of sight effect, and that the
redshift evolution of the spin temperature does not arises due to a selection
effect. All of these are consistent with a redshift evolution of the warm gas
fraction in Damped Lyman-alpha systems.",1308.4410v1
2016-11-17,A stable partitioned FSI algorithm for rigid bodies and incompressible flow. Part II: General formulation,"A stable partitioned algorithm is developed for fluid-structure interaction
(FSI) problems involving viscous incompressible flow and rigid bodies. This
{\em added-mass partitioned} (AMP) algorithm remains stable, without
sub-iterations, for light and even zero mass rigid bodies when added-mass and
viscous added-damping effects are large. The scheme is based on a generalized
Robin interface condition for the fluid pressure that includes terms involving
the linear acceleration and angular acceleration of the rigid body. Added mass
effects are handled in the Robin condition by inclusion of a boundary integral
term that depends on the pressure. Added-damping effects due to the viscous
shear forces on the body are treated by inclusion of added-damping tensors that
are derived through a linearization of the integrals defining the force and
torque. Added-damping effects may be important at low Reynolds number, or, for
example, in the case of a rotating cylinder or rotating sphere when the
rotational moments of inertia are small. In this second part of a two-part
series, the general formulation of the AMP scheme is presented including the
form of the AMP interface conditions and added-damping tensors for general
geometries. A fully second-order accurate implementation of the AMP scheme is
developed in two dimensions based on a fractional-step method for the
incompressible Navier-Stokes equations using finite difference methods and
overlapping grids to handle the moving geometry. The numerical scheme is
verified on a number of difficult benchmark problems.",1611.05703v2
2017-04-18,Critical pairing fluctuations in the normal state of a superconductor: pseudogap and quasi-particle damping,"We study the effect of critical pairing fluctuations on the electronic
properties in the normal state of a clean superconductor in three dimensions.
Using a functional renormalization group approach to take the non-Gaussian
nature of critical fluctuations into account, we show microscopically that in
the BCS regime, where the inverse coherence length is much smaller than the
Fermi wavevector, critical pairing fluctuations give rise to a non-analytic
contribution to the quasi-particle damping of order $ T_c \sqrt{Gi} \ln ( 80 /
Gi )$, where the Ginzburg-Levanyuk number $Gi$ is a dimensionless measure for
the width of the critical region. As a consequence, there is a temperature
window above $T_c$ where the quasiparticle damping due to critical pairing
fluctuations can be larger than the usual $T^2$-Fermi liquid damping due to
non-critical scattering processes. On the other hand, in the strong coupling
regime where $Gi$ is of order unity, we find that the quasiparticle damping due
to critical pairing fluctuations is proportional to the temperature. Moreover,
we show that in the vicinity of the critical temperature $T_c$ the electronic
density of states exhibits a fluctuation-induced pseudogap. We also use
functional renormalization group methods to derive and classify various types
of processes induced by the pairing interaction in Fermi systems close to the
superconducting instability.",1704.05282v2
2018-05-26,Critical collapse of ultra-relativistic fluids: damping or growth of aspherical deformations,"We perform fully nonlinear numerical simulations to study aspherical
deformations of the critical self-similar solution in the gravitational
collapse of ultra-relativistic fluids. Adopting a perturbative calculation,
Gundlach predicted that these perturbations behave like damped or growing
oscillations, with the frequency and damping (or growth) rates depending on the
equation of state. We consider a number of different equations of state and
degrees of asphericity and find very good agreement with the findings of
Gundlach for polar $\ell = 2$ modes. For sufficiently soft equations of state,
the modes are damped, meaning that, in the limit of perfect fine-tuning, the
spherically symmetric critical solution is recovered. We find that the degree
of asphericity has at most a small effect on the frequency and damping
parameter, or on the critical exponents in the power-law scalings. Our findings
also confirm, for the first time, Gundlach's prediction that the $\ell = 2$
modes become unstable for sufficiently stiff equations of state. In this regime
the spherically symmetric self-similar solution can no longer be recovered by
fine-tuning to the black-hole threshold, and one can no longer expect power-law
scaling to hold to arbitrarily small scales.",1805.10442v1
2008-07-28,"Thermal fluctuations in moderately damped Josephson junctions: Multiple escape and retrapping, switching- and return-current distributions and hysteresis","A crossover at a temperature T* in the temperature dependence of the width s
of the distribution of switching currents of moderately damped Josephson
junctions has been reported in a number of recent publications, with positive
ds/dT and IV characteristics associated with underdamped behaviour for lower
temperatures T<T*, and negative ds/dT and IV characteristics resembling
overdamped behaviour for higher temperatures T>T*. We have investigated in
detail the behaviour of Josephson junctions around the temperature T* by using
Monte Carlo simulations including retrapping from the running state into the
supercurrent state as given by the model of Ben-Jacob et al. We develop
discussion of the important role of multiple escape and retrapping events in
the moderate-damping regime, in particular considering the behaviour in the
region close to T*. We show that the behaviour is more fully understood by
considering two crossover temperatures, and that the shape of the distribution
and s(T) around T*, as well as at lower T<T*, are largely determined by the
shape of the conventional thermally activated switching distribution. We show
that the characteristic temperatures T* are not unique for a particular
Josephson junction, but have some dependence on the ramp rate of the applied
bias current. We also consider hysteresis in moderately damped Josephson
junctions and discuss the less commonly measured distribution of return
currents for a decreasing current ramp. We find that some hysteresis should be
expected to persist above T* and we highlight the importance, even well below
T*, of accounting properly for thermal fluctuations when determining the
damping parameter Q.",0807.4502v1
2013-09-26,Non-Landau damping of magnetic excitations in systems with localized and itinerant electrons,"We discuss the form of the damping of magnetic excitations in a metal near a
ferromagnetic instability. The paramagnon theory predicts that the damping term
should have the form $\Omega/\Gamma (q)$ with $\Gamma (q) \propto q$ (the
Landau damping). However, the experiments on uranium metallic compounds UGe$_2$
and UCoGe showed that $\Gamma (q)$ tends to a constant value at vanishing $q$.
A non-zero $\Gamma (0)$ is impossible in systems with one type of carriers
(either localized or itinerant) because it would violate the spin conservation.
It has been conjectured recently that a non-zero $\Gamma (q)$ in UGe$_2$ and
UCoGe may be due to the presence of both localized and itinerant electrons in
these materials, with ferromagnetism involving predominantly localized spins.
We present microscopic analysis of the damping of near-critical localized
excitations due to interaction with itinerant carriers. We show explicitly how
the presence of two types of electrons breaks the cancellation between the
contributions to $\Gamma (0)$ from self-energy and vertex correction insertions
into the spin polarization bubble and discuss the special role of the
Aslamazov-Larkin processes. We show that $\Gamma (0)$ increases with $T$ both
in the paramagnetic and ferromagnetic regions, but in-between it has a peak at
$T_c$. We compare our theory with the available experimental data.",1309.7065v3
2014-06-16,Design of the Readout Electronics for the Qualification Model of DAMPE BGO Calorimeter,"The DAMPE (DArk Matter Particle Explorer) is a scientific satellite being
developed in China, aimed at cosmic ray study, gamma ray astronomy, and
searching for the clue of dark matter particles, with a planned mission period
of more than 3 years and an orbit altitude of about 500 km. The BGO
Calorimeter, which consists of 308 BGO (Bismuth Germanate Oxid) crystal bars,
616 PMTs (photomultiplier tubes) and 1848 dynode signals, has approximately 32
radiation lengths. It is a crucial sub-detector of the DAMPE payload, with the
functions of precisely measuring the energy of cosmic particles from 5 GeV to
10TeV, distinguishing positrons/electrons and gamma rays from hadron
background, and providing trigger information for the whole DAMPE payload. The
dynamic range for a single BGO crystal is about 2?105 and there are 1848
detector signals in total. To build such an instrument in space, the major
design challenges for the readout electronics come from the large dynamic
range, the high integrity inside the very compact structure, the strict power
supply budget and the long term reliability to survive the hush environment
during launch and in orbit. Currently the DAMPE mission is in the end of QM
(Qualification Model) stage. This paper presents a detailed description of the
readout electronics for the BGO calorimeter.",1406.3886v1
2016-05-09,Storage-ring Electron Cooler for Relativistic Ion Beams,"Application of electron cooling at ion energies above a few GeV has been
limited due to reduction of electron cooling efficiency with energy and
difficulty in producing and accelerating a high-current high-quality electron
beam. A high-current storage-ring electron cooler offers a solution to both of
these problems by maintaining high cooling beam quality through
naturally-occurring synchrotron radiation damping of the electron beam.
However, the range of ion energies where storage-ring electron cooling can be
used has been limited by low electron beam damping rates at low ion energies
and high equilibrium electron energy spread at high ion energies. This paper
reports a development of a storage ring based cooler consisting of two sections
with significantly different energies: the cooling and damping sections. The
electron energy and other parameters in the cooling section are adjusted for
optimum cooling of a stored ion beam. The beam parameters in the damping
section are adjusted for optimum damping of the electron beam. The necessary
energy difference is provided by an energy recovering SRF structure. A
prototype linear optics of such storage-ring cooler and initial tracking
simulations are presented and some potential issues such as coherent
synchrotron radiation and beam break up are discussed.",1605.02594v1
2017-10-30,Enhancement of intrinsic magnetic damping in defect-free epitaxial Fe3O4 thin films,"We have investigated the magnetic damping of precessional spin dynamics in
defect-controlled epitaxial grown Fe$_3$O$_4$(111)/Yttria-stabilized Zirconia
(YSZ) nanoscale films by all-optical pump-probe measurements. The intrinsic
damping constant of the defect-free Fe$_3$O$_4$ film is found to be strikingly
larger than that of the as-grown Fe$_3$O$_4$ film with structural defects. We
demonstrate that the population of the first-order perpendicular standing spin
wave (PSSW) mode, which is exclusively observed in the defect-free film under
sufficiently high external magnetic fields, leads to the enhancement of the
magnetic damping of the uniform precession (Kittel) mode. We propose a physical
picture in which the PSSW mode acts as an additional channel for the extra
energy dissipation of the Kittel mode. The energy transfer from Kittel mode to
PSSW mode increases as in-plane magnetization precession becomes more uniform,
resulting in the unique intrinsic magnetic damping enhancement in the
defect-free Fe$_3$O$_4$ film.",1710.10938v2
2018-10-16,The Solution to the Differential Equation with Linear Damping describing a Physical Systems governed by a Cubic Energy Potential,"An analytical solution to the nonlinear differential equation describing the
equation of motion of a particle moving in an unforced physical system with
linear damping, governed by a cubic potential well, is presented in terms of
the Jacobi elliptic functions. In the attractive region of the potential the
system becomes an anharmonic damped oscillator, however with asymmetric
displacement. An expression for the period of oscillation is derived, which for
a nonlinear damped system is time dependent, and in particular it contains a
quartic root of an exponentially decaying term in the denominator. Initially
the period is longer as compared to that of a linear oscillator, however
gradually it decreases to that of a linear damped oscillator.
  Transforming the undamped nonlinear differential equation into the
differential equation describing orbital motion of planets, the perihelion
advance of Mercury can be estimated to 42.98 arcseconds/century, close to
present day observations of 43.1 arcseconds/century.
  Some familiarity with the Jacobi elliptic functions is required, in
particular with respect to the differential behavior of these functions,
however, they are standard functions of advanced mathematical computer algebra
tools. The expression derived for the solution to the nonlinear physical
system, and in particular the expression for the period of oscillation, is
useful for an accurate evaluation of experiments in introductory and advanced
physics labs, but also of interest for specialists working with nonlinear
phenomena governed by the cubic potential well.",1810.10336v1
2019-07-16,Damping of slow magnetoacoustic oscillations by the misbalance between heating and cooling processes in the solar corona,"Rapidly decaying slow magnetoacoustic waves are regularly observed in the
solar coronal structures, offering a promising tool for a seismological
diagnostics of the coronal plasma, including its thermodynamical properties.
The effect of damping of standing slow magnetoacoustic oscillations in the
solar coronal loops is investigated accounting for the field-aligned thermal
conductivity and a wave-induced misbalance between radiative cooling and some
unspecified heating rates. The non-adiabatic terms were allowed to be
arbitrarily large, corresponding to the observed values. The thermal
conductivity was taken in its classical form, and a power-law dependence of the
heating function on the density and temperature was assumed. The analysis was
conducted in the linear regime and in the infinite magnetic field
approximation. The wave dynamics is found to be highly sensitive to the
characteristic time scales of the thermal misbalance. Depending on certain
values of the misbalance time scales three regimes of the wave evolution were
identified, namely the regime of a suppressed damping, enhanced damping where
the damping rate drops down to the observational values, and acoustic
over-stability. The specific regime is determined by the dependences of the
radiative cooling and heating functions on thermodynamical parameters of the
plasma in the vicinity of the perturbed thermal equilibrium. The comparison of
the observed and theoretically derived decay times and oscillation periods
allows us to constrain the coronal heating function. For typical coronal
parameters, the observed properties of standing slow magnetoacoustic
oscillations could be readily reproduced with a reasonable choice of the
heating function.",1907.07051v1
2019-07-29,Breather arrest in a chain of damped oscillators with Hertzian contact,"We explore breather propagation in the damped oscillatory chain with
essentially nonlinear (non-linearizable) nearest-neighbour coupling.
Combination of the damping and the substantially nonlinear coupling leads to
rather unusual two-stage pattern of the breather propagation. The first stage
occurs at finite fragment of the chain and is characterized by power-law decay
of the breather amplitude. The second stage is characterized by extremely small
breather amplitudes that decay hyper-exponentially with the site number. Thus,
practically, one can speak about finite penetration depth of the breather. This
phenomenon is referred to as breather arrest (BA). As particular example, we
explore the chain with Hertzian contacts. Dependencies of the breather
penetration depth on the initial excitation and on the damping coefficient on
the breather penetration depth obey power laws. The results are rationalized by
considering beating responses in a system of two damped linear oscillators with
strongly nonlinear (non-linearizable) coupling. Initial excitation of one of
these oscillators leads to strictly finite number of beating cycles. Then, the
beating cycle in this simplified system is associated with the passage of the
discrete breather between the neighbouring sites in the chain. Somewhat
surprisingly, this simplified model reliably predicts main quantitative
features of the breather arrest in the chain, including the exponents in
numerically observed power laws.",1907.12462v1
2019-09-11,Critical corrections to formulations of nonlinear energy dissipation of ultrasonically excited bubbles and a unifying parameter to asses and enhance bubble activity in applications,"Nonlinear oscillations of bubbles can significantly increase the attenuation
of the host media. Optimization of bubble related applications needs a
realistic estimation of the medium attenuation and bubble activity. A correct
estimation of the wave attenuation in bubbly media requires an accurate
estimation of the power dissipated by nonlinear oscillations of bubbles.
Pioneering work of Louisnard \cite{1} meticulously derived the nonlinear energy
terms for viscous and thermal damping; however, radiation damping arising from
the compressibility of the liquid was neglected. Jamshidi $\&$ Brenner \cite{2}
have considered the effects of the compressibility of the liquid and showed
that damping due to radiation becomes the most significant factor at pressures
above the blake threshold. Despite the improvement in their formulation;
however, the radiation damping term estimates non-physical values for some
frequency and pressure regions including near resonance oscillations. Thus, the
new terms arising from the compressibility of the liquid needs critical
assessment. In this work, we provide critical corrections to the present
formulations. Importance of the new corrections are highlighted by the
scattering to damping ratio (STDR). We then introduce a unifying parameter to
assess the efficacy of applications; this parameter is defined as the
multiplication of maximum scattered pressure by STDR.",1909.04864v1
2019-09-14,Measurement-Based Wide-Area Damping of Inter-Area Oscillations based on MIMO Identification,"Interconnected power grid exhibits oscillatory response after a disturbance
in the system. One such type of oscillations, the inter-area oscillations has
the oscillation frequency in the range of 0.1 to 1 Hz. The damping of
inter-area oscillations is difficult with local controllers, but it can be
achieved using a Wide Area Damping Controller (WADC). For effective control,
the input to the WADC should be the most observable signal and the WADC output
should be sent to the most controllable generator. This paper presents a
measurement-based novel algorithm for multi-input-multi-output (MIMO) transfer
function identification of the power system based on optimization to estimate
such oscillation frequencies. Based on the MIMO transfer function the optimal
control loop for WADC is estimated. The WADC design is based on the discrete
linear quadratic regulator (DLQR) and Kalman filtering for damping of
inter-area oscillations. Since the MIMO identification is based on actual
measurements, the proposed method can accurately monitor changes in the power
grid whereas the conventional methods are based on small-signal analysis of a
linearized model which does not consider changing operating conditions. The
overall algorithm is implemented and validated on a RTDS/RSCAD and MATLAB
real-time co-simulation platform using two-area and IEEE 39 bus power system
models.",1909.06687v1
2020-02-07,"Engineering Co$_2$MnAl$_x$Si$_{1-x}$ Heusler compounds as a model system to correlate spin polarization, intrinsic Gilbert damping and ultrafast demagnetization","Engineering of magnetic materials for developing better spintronic
applications relies on the control of two key parameters: the spin polarization
and the Gilbert damping responsible for the spin angular momentum dissipation.
Both of them are expected to affect the ultrafast magnetization dynamics
occurring on the femtosecond time scale. Here, we use engineered Co2MnAlxSi1-x
Heusler compounds to adjust the degree of spin polarization P from 60 to 100%
and investigate how it correlates with the damping. We demonstrate
experimentally that the damping decreases when increasing the spin polarization
from 1.1 10-3 for Co2MnAl with 63% spin polarization to an ultra-low value of
4.10-4 for the half-metal magnet Co2MnSi. This allows us investigating the
relation between these two parameters and the ultrafast demagnetization time
characterizing the loss of magnetization occurring after femtosecond laser
pulse excitation. The demagnetization time is observed to be inversely
proportional to 1-P and as a consequence to the magnetic damping, which can be
attributed to the similarity of the spin angular momentum dissipation processes
responsible for these two effects. Altogether, our high quality Heusler
compounds allow controlling the band structure and therefore the channel for
spin angular momentum dissipation.",2002.02686v1
2020-12-28,On the Efficacy of Friction Damping in the Presence of Nonlinear Modal Interactions,"This work addresses friction-induced modal interactions in jointed
structures, and their effects on the passive mitigation of vibrations by means
of friction damping. Under the condition of (nearly) commensurable natural
frequencies, the nonlinear character of friction can cause so-called nonlinear
modal interactions. If harmonic forcing near the natural frequency of a
specific mode is applied, for instance, another mode may be excited due to
nonlinear energy transfer and thus contribute considerably to the vibration
response. We investigate how this phenomenon affects the performance of
friction damping. To this end, we study the steady-state, periodic forced
vibrations of a system of two beams connected via a local mechanical friction
joint. The system can be tuned to continuously adjust the ratio between the
first two natural frequencies in the range around the $1:3$ internal resonance,
in order to trigger or suppress the emergence of modal interactions. Due to the
re-distribution of the vibration energy, the vibration level can in fact be
reduced in certain situations. However, in other situations, the multi-harmonic
character of the vibration has detrimental effects on the effective damping
provided by the friction joint. The resulting response level can be
significantly larger than in the absence of modal interactions. Moreover, it is
shown that the vibration behavior is highly sensitive in the neighborhood of
internal resonances. It is thus concluded that the condition of internal
resonance should be avoided in the design of friction-damped systems.",2101.03232v1
2017-05-29,Probing decoherence in plasmonic waveguides in the quantum regime,"We experimentally investigate the decoherence of single surface plasmon
polaritons in metal stripe waveguides. In our study we use a Mach-Zehnder
configuration previously considered for measuring decoherence in atomic,
electronic and photonic systems. By placing waveguides of different length in
one arm we are able to measure the amplitude damping time T_1 = 1.90 +/- 0.01 x
10^-14 s, pure phase damping time T_2^* = 11.19 +/- 4.89 x 10^-14 s and total
phase damping time T_2 = 2.83 +/- 0.32 x 10^-14 s. We find that decoherence is
mainly due to amplitude damping and thus loss arising from inelastic electron
and photon scattering plays the most important role in the decoherence of
plasmonic waveguides in the quantum regime. However, pure phase damping is not
completely negligible. The results will be useful in the design of plasmonic
waveguide systems for carrying out phase-sensitive quantum applications, such
as quantum sensing. The probing techniques developed may also be applied to
other plasmonic nanostructures, such as those used as nanoantennas, as unit
cells in metamaterials and as nanotraps for cold atoms.",1705.10344v2
2017-11-20,Spin Pumping in Ion-beam Sputtered Co_{2}FeAl/Mo Bilayers:Interfacial Gilbert Damping,"The spin pumping mechanism and associated interfacial Gilbert damping are
demonstrated in ion-beam sputtered Co2FeAl (CFA) /Mo bilayer thin films
employing ferromagnetic resonance spectroscopy. The dependence of the net spin
current transportation on Mo layer thickness, 0 to 10 nm, and the enhancement
of the net effective Gilbert damping are reported. The experimental data has
been analyzed using spin pumping theory in terms of spin current pumped through
the ferromagnet /nonmagnetic metal interface to deduce the effective spin
mixing conductance and the spin-diffusion length, which are estimated to be
1.16(0.19)x10^19 m^-2 and 3.50(0.35)nm, respectively. The damping constant is
found to be 8.4(0.3)x10^-3 in the Mo(3.5nm) capped CFA(8nm) sample
corresponding to a ~42% enhancement of the original Gilbert damping
(6.0(0.3)x10^-3) in the uncapped CFA layer. This is further confirmed by
inserting a Cu dusting layer which reduces the spin transport across the CFA
/Mo interface. The Mo layer thickness dependent net spin current density is
found to lie in the range of 1-3 MAm^-2, which also provides additional
quantitative evidence of spin pumping in this bilayer thin film system.",1711.07455v1
2018-06-19,Non-linear Relaxation of Interacting Bosons Coherently Driven on a Narrow Optical Transition,"We study the dynamics of a two-component Bose-Einstein condensate (BEC) of
$^{174}$Yb atoms coherently driven on a narrow optical transition. The
excitation transfers the BEC to a superposition of states with different
internal and momentum quantum numbers. We observe a crossover with decreasing
driving strength between a regime of damped oscillations, where coherent
driving prevails, and an incoherent regime, where relaxation takes over.
Several relaxation mechanisms are involved: inelastic losses involving two
excited atoms, leading to a non-exponential decay of populations; Doppler
broadening due to the finite momentum width of the BEC and inhomogeneous
elastic interactions, both leading to dephasing and to damping of the
oscillations. We compare our observations to a two-component Gross-Pitaevskii
(GP) model that fully includes these effects. For small or moderate densities,
the damping of the oscillations is mostly due to Doppler broadening. In this
regime, we find excellent agreement between the model and the experimental
results. For higher densities, the role of interactions increases and so does
the damping rate of the oscillations. The damping in the GP model is less
pronounced than in the experiment, possibly a hint for many-body effects not
captured by the mean-field description.",1806.07210v2
2018-07-20,Another view on Gilbert damping in two-dimensional ferromagnets,"A keen interest towards technological implications of spin-orbit driven
magnetization dynamics requests a proper theoretical description, especially in
the context of a microscopic framework, to be developed. Indeed, magnetization
dynamics is so far approached within Landau-Lifshitz-Gilbert equation which
characterizes torques on magnetization on purely phenomenological grounds.
Particularly, spin-orbit coupling does not respect spin conservation, leading
thus to angular momentum transfer to lattice and damping as a result. This
mechanism is accounted by the Gilbert damping torque which describes relaxation
of the magnetization to equilibrium. In this study we work out a microscopic
Kubo-St\v{r}eda formula for the components of the Gilbert damping tensor and
apply the elaborated formalism to a two-dimensional Rashba ferromagnet in the
weak disorder limit. We show that an exact analytical expression corresponding
to the Gilbert damping parameter manifests linear dependence on the scattering
rate and retains the constant value up to room temperature when no vibrational
degrees of freedom are present in the system. We argue that the methodology
developed in this paper can be safely applied to bilayers made of non- and
ferromagnetic metals, e.g., CoPt.",1807.07897v2
2019-01-10,Damping and softening of transverse acoustic phonons in colossal magnetoresistive La$_{0.7}$Ca$_{0.3}$MnO$_3$ and La$_{0.7}$Sr$_{0.3}$MnO$_3$,"Neutron spectroscopy is used to probe transverse acoustic phonons near the
(2, 2, 0) Bragg position in colossal magnetoresistive La0.7Ca0.3MnO3 and
La0.7Sr0.3MnO3. Upon warming to temperatures near Tc = 257 K the phonon peaks
in La0.7Ca0.3MnO3 soften and damp significantly with the phonon half width at
half maximum approaching 2.5 meV for phonons at a reduced wave vector of q =
(0.2, 0.2, 0). Concurrently a quasielastic component develops that dominates
the spectrum near the polaron position at high temperatures. This quasielastic
scattering is ~5 times more intense near Tc than in La0.7Sr0.3MnO3 despite
comparable structural distortions in the two. The damping becomes more
significant near the polaron position with a temperature dependence similar to
that of polaron structural distortions. An applied magnetic field of 9.5 T only
partially reverses the damping and quasielastic component, despite smaller
fields being sufficient to drive the colossal magnetoresistive effect. The
phonon energy, on the other hand, is unaffected by field. The damping in
La0.7Sr0.3MnO3 near Tc at a reduced wave vector of q = (0.25, 0.25, 0) is
significantly smaller but displays a similar trend with an applied magnetic
field.",1901.03394v1
2019-03-13,Inference of magnetic field strength and density from damped transverse coronal waves,"A classic application of coronal seismology uses transverse oscillations of
waveguides to obtain estimates of the magnetic field strength. The procedure
requires information on the density of the structures. Often, it ignores the
damping of the oscillations. We computed marginal posteriors for parameters
such as the waveguide density; the density contrast; the transverse
inhomogeneity length-scale; and the magnetic field strength, under the
assumption that the oscillations can be modelled as standing
magnetohydrodynamic (MHD) kink modes damped by resonant absorption. Our results
show that the magnetic field strength can be properly inferred, even if the
densities inside and outside the structure are largely unknown. Incorporating
observational estimates of plasma density further constrains the obtained
posteriors. The amount of information one is willing to include (a priori) for
the density and the density contrast influences their corresponding posteriors,
but very little the inferred magnetic field strength. The decision to include
or leave out the information on the damping and the damping time-scales have a
minimal impact on the obtained magnetic field strength. In contrast to the
classic method which provides with numerical estimates with error bars or
possible ranges of variation for the magnetic field strength, Bayesian methods
offer the full distribution of plausibility over the considered range of
possible values. The methods are applied to available datasets of observed
transverse loop oscillations, can be extended to prominence fine structures or
chromospheric spicules and implemented to propagating waves in addition to
standing oscillations.",1903.05437v1
2019-03-14,A metal-poor damped Ly-alpha system at redshift 6.4,"We identify a strong Ly-alpha damping wing profile in the spectrum of the
quasar P183+05 at z=6.4386. Given the detection of several narrow metal
absorption lines at z=6.40392, the most likely explanation for the absorption
profile is that it is due to a damped Ly-alpha system. However, in order to
match the data a contribution of an intergalactic medium 5-38% neutral or
additional weaker absorbers near the quasar is also required. The absorption
system presented here is the most distant damped Ly-alpha system currently
known. We estimate an HI column density ($10^{20.68\pm0.25}\,$cm$^{-2}$),
metallicity ([O/H]$=-2.92\pm 0.32$), and relative chemical abundances of a
system consistent with a low-mass galaxy during the first Gyr of the universe.
This object is among the most metal-poor damped Ly-alpha systems known and,
even though it is observed only ~850 Myr after the big bang, its relative
abundances do not show signatures of chemical enrichment by Population III
stars.",1903.06186v2
2019-04-30,DmpIRFs and DmpST: DAMPE Instrument Response Functions and Science Tools for Gamma-Ray Data Analysis,"GeV gamma ray is an important observation target of DArk Matter Particle
Explorer (DAMPE) for indirect dark matter searching and high energy
astrophysics. We present in this work a set of accurate instrument response
functions of DAMPE (DmpIRFs) including the effective area, point-spread
function and energy dispersion that are crucial for the gamma-ray data analysis
based on the high statistics simulation data. A dedicated software named DmpST
is developed to facilitate the scientific analyses of DAMPE gamma-ray data.
Considering the limited number of photons and the angular resolution of DAMPE,
the maximum likelihood method is adopted in the DmpST to better disentangle
different source components. The basic mathematics and the framework regarding
this software are also introduced in this paper.",1904.13098v1
2019-08-22,Influence of structure and cation distribution on magnetic anisotropy and damping in Zn/Al doped nickel ferrites,"An in-depth analysis of Zn/Al doped nickel ferrites grown by reactive
magnetron sputtering is relevant due to their promising characteristics for
applications in spintronics. The material is insulating and ferromagnetic at
room temperature with an additional low magnetic damping. By studying the
complex interplay between strain and cation distribution their impact on the
magnetic properties, i.e. anisotropy, damping and g-factor is unravelled. In
particular, a strong influence of the lattice site occupation of
Ni$^{2+}_{\text{Td}}$ and cation coordination of Fe$^{2+}_{\text{Oh}}$ on the
intrinsic damping is found. Furthermore, the critical role of the incorporation
of Zn$^{2+}$ and Al$^{3+}$ is evidenced by comparison with a sample of altered
composition. Especially, the dopant Zn$^{2+}$ is evidenced as a tuning factor
for Ni$^{2+}_{\text{Td}}$ and therefore unquenched orbital moments directly
controlling the g-factor. A strain-independent reduction of the magnetic
anisotropy and damping by adapting the cation distribution is demonstrated.",1908.08257v3
2019-12-09,Analytical solution of linearized equations of the Morris-Lecar neuron model at large constant stimulation,"The classical biophysical Morris-Lecar model of neuronal excitability
predicts that upon stimulation of the neuron with a sufficiently large constant
depolarizing current there exists a finite interval of the current values where
periodic spike generation occurs. Above the upper boundary of this interval,
there is four-stage damping of the spike amplitude: 1) minor primary damping,
which reflects a typical transient to stationary dynamic state, 2) plateau of
nearly undamped periodic oscillations, 3) strong damping, and 4) reaching a
constant asymptotic value of the neuron potential. We have shown that in the
vicinity of the asymptote the Morris-Lecar equations can be reduced to the
standard equation for exponentially damped harmonic oscillations. Importantly,
all coefficients of this equation can be explicitly expressed through
parameters of the original Morris-Lecar model, enabling direct comparison of
the numerical and analytical solutions for the neuron potential dynamics at
later stages of the spike amplitude damping.",1912.04083v4
2020-03-16,Spin-orbit torques originating from bulk and interface in Pt-based structures,"We investigated spin-orbit torques in prototypical Pt-based spintronic
devices. We found that, in Pt/Ni and Pt/Fe bilayers, the damping-like torque
efficiency depends on the thickness of the Pt layer. We also found that the
damping-like torque efficiency is almost identical in the Pt/Ni and Pt/Fe
bilayers despite the stronger spin memory loss at the Pt/Fe interface. These
results suggest that although the dominant source of the damping-like torque is
the bulk spin Hall effect in the Pt layer, a sizable damping-like torque is
generated by the interface in the Pt/Fe bilayer due to the stronger interfacial
spin-orbit coupling. In contrast to the damping-like torque, whose magnitude
and sign are almost identical in the Pt/Ni and Pt/Fe bilayers, the field-like
torque strongly depends on the choice of the ferromagnetic layer. The sign of
the field-like torque originating from the bulk spin Hall effect in the Pt
layer is opposite between the Pt/Ni and Pt/Fe bilayers, which can be attributed
to the opposite sign of the imaginary part of the spin-mixing conductance.
These results demonstrate that the spin-orbit torques are quite sensitive to
the electronic structure of the FM layer.",2003.07271v2
2020-03-23,Heat-like and wave-like lifespan estimates for solutions of semilinear damped wave equations via a Kato's type lemma,"In this paper we study several semilinear damped wave equations with
""subcritical"" nonlinearities, focusing on demonstrating lifespan estimates for
energy solutions. Our main concern is on equations with scale-invariant damping
and mass. Under different assumptions imposed on the initial data, lifespan
estimates from above are clearly showed. The key fact is that we find
""transition surfaces"", which distinguish lifespan estimates between ""wave-like""
and ""heat-like"" behaviours. Moreover we conjecture that the lifespan estimates
on the ""transition surfaces"" can be logarithmically improved. As direct
consequences, we reorganize the blow-up results and lifespan estimates for the
massless case in which the ""transition surfaces"" degenerate to ""transition
curves"". Furthermore, we obtain improved lifespan estimates in one space
dimension, comparing to the known results. We also study semilinear wave
equations with the scattering damping and negative mass term, and find that if
the decay rate of the mass term equals to 2, the lifespan estimate is the same
as one special case of the equations with the scale-invariant damping and
positive mass. The main strategy of the proof consists of a Kato's type lemma
in integral form, which is established by iteration argument.",2003.10578v1
2020-09-03,Dynamics of magnetic collective modes in the square and triangular lattice Mott insulators at finite temperature,"We study the equilibrium dynamics of magnetic moments in the Mott insulating
phase of the Hubbard model on the square and triangular lattice. We rewrite the
Hubbard interaction in terms of an auxiliary vector field and use a recently
developed Langevin scheme to study its dynamics. A thermal `noise', derivable
approximately from the Keldysh formalism, allows us to study the effect of
finite temperature. At strong coupling, $U \gg t$, where $U$ is the local
repulsion and $t$ the nearest neighbour hopping, our results reproduce the well
known dynamics of the nearest neighbour Heisenberg model with exchange $J \sim
{\cal O}(t^2/U)$. These include crossover from weakly damped dispersive modes
at temperature $T \ll J$ to strong damping at $T \sim {\cal O}(J)$, and
diffusive dynamics at $T \gg J$. The crossover temperatures are naturally
proportional to $J$. To highlight the progressive deviation from Heisenberg
physics as $U/t$ reduces we compute an effective exchange scale $J_{eff}(U)$
from the low temperature spin wave velocity. We discover two features in the
dynamical behaviour with decreasing $U/t$: (i)~the low temperature dispersion
deviates from the Heisenberg result, as expected, due to longer range and
multispin interactions, and (ii)~the crossovers between weak damping, strong
damping, and diffusion take place at noticeably lower values of $T/J_{eff}$. We
relate this to enhanced mode coupling, in particular to thermal amplitude
fluctuations, at weaker $U/t$. A comparison of the square and triangular
lattice reveals the additional effect of geometric frustration on damping.",2009.01833v2
2020-09-15,Classification of the mechanisms of wave energy dissipation in the nonlinear oscillations of coated and uncoated bubbles,"Acoustic waves are dissipated when they pass through bubbly media.
Dissipation by bubbles takes place through thermal damping (Td), radiation
damping (Rd) and damping due to the friction of the liquid (Ld) and friction of
the coating (Cd). Knowledge of the contributions of the Td, Rd, Ld and Cd
during nonlinear bubble oscillations will help in optimizing bubble and
ultrasound exposure parameters for the relevant applications by maximizing a
desirable parameter. In this work we investigate the mechanisms of dissipation
in bubble oscillations and their contribution to the total damping (Wtotal) in
various nonlinear regimes. By using bifurcation analysis, we have classified
nonlinear dynamics of bubbles that are sonicated with their 3rd superharmonic
(SuH) and 2nd SuH resonance frequency (fr), pressure dependent resonance
frequency (PDfr), fr, subharmonic (SH) resonance (fsh=2fr), pressure dependent
SH resonance (PDfsh) and 1/3 order SH resonance. The corresponding Td, Rd, Ld,
Cd, Wtotal, scattering to dissipation ratio (STDR), maximum wall velocity and
maximum back-scattered pressure from non-destructive oscillations of bubbles
were calculated and analyzed using the bifurcation diagrams. We classified
different regimes of dissipation and provided parameter regions in which a
particular parameter of interest (e.g. Rd) can be enhanced. Afterwards enhanced
bubble activity is linked to some relevant applications in ultrasound. This
paper represents the first comprehensive analysis of the nonlinear oscillations
regimes and the corresponding damping mechanisms.",2009.07380v1
2020-11-18,The effect of redshift degeneracy and the damping effect of viscous medium on the information extracted from gravitational wave signals,"Considering the cosmological redshift $z_c$ , the mass of GW source extracted
from GW signal is $1+z_c$ times larger than its intrinsic value, and distance
between detector and GW source should be regarded as luminosity distance.
However, besides cosmological redshift, there are other kinds of redshifts
should be considered, which is actually ignored, in the analysis of GW data,
such as Doppler redshift and gravitational redshift, so the parameters
extracted from GW may deviate from their intrinsic values. Another factor that
may affect GW is the viscous medium in propagation path of GW, which may damp
the GW with a damping rate of $16{\pi}G{\eta}$. Some studies indicate dark
matter may interact with each other, thus dark matter may be the origin of
viscosity of cosmic medium. Then the GW may be rapidly damped by the viscous
medium that is made of dark matter, such as dark matter ""mini-spike"" around
intermediate mass black hole. In this article, we mainly discuss how Doppler
and gravitational redshift, together with the damping effect of viscous medium,
affect the information, such as the mass and redshift of GW source, extracted
from GW signals.",2011.09169v2
2021-06-30,Origin of Nonlinear Damping due to Mode Coupling in Auto-Oscillatory Modes Strongly Driven by Spin-Orbit Torque,"We investigate the physical origin of nonlinear damping due to mode coupling
between several auto-oscillatory modes driven by spin-orbit torque in
constricted Py/Pt heterostructures by examining the dependence of
auto-oscillation on temperature and applied field orientation. We observe a
transition in the nonlinear damping of the auto-oscillation modes extracted
from the total oscillation power as a function of drive current, which
coincides with the onset of power redistribution amongst several modes and the
crossover from linewidth narrowing to linewidth broadening in all individual
modes. This indicates the activation of another relaxation process by nonlinear
magnon-magnon scattering within the modes. We also find that both nonlinear
damping and threshold current in the mode-interaction damping regime at high
drive current after transition are temperature independent, suggesting that the
mode coupling occurs dominantly through a non-thermal magnon scattering process
via a dipole or exchange interaction rather than thermally excited
magnon-mediated scattering. This finding presents a promising pathway to
overcome the current limitations of efficiently controlling the interaction
between two highly nonlinear magnetic oscillators to prevent mode crosstalk or
inter-mode energy transfer and deepens understanding of complex nonlinear spin
dynamics in multimode spin wave systems.",2107.00150v2
2021-07-15,On the long-time behavior for a damped Navier-Stokes-Bardina model,"In this paper, we consider a damped Navier-Stokes-Bardina model posed on the
whole three-dimensional. These equations have an important physical motivation
and they arise from some oceanic model. From the mathematical point of view,
they write down as the well-know Navier-Stokes equations with an additional
nonlocal operator in their nonlinear transport term, and moreover, with an
additional damping term depending of a parameter $\beta>0$. We study first the
existence and uniqueness of global in time weak solutions in the energy space.
Thereafter, our main objective is to describe the long time behavior of these
solutions. For this, we use some tools in the theory of dynamical systems to
prove the existence of a global attractor, which is a compact subset in the
energy space attracting all the weak solutions when the time goes to infinity.
Moreover, we derive an upper bound for the fractal dimension of the global
attractor associated to these equations.
  Finally, we find a range of values for the damping parameter $\beta>0$, where
we are able to give an acutely description of the internal structure of the
global attractor. More precisely, we prove that the global attractor only
contains the stationary (time-independing) solution of the damped
Navier-Stokes-Bardina equations.",2107.07070v2
2021-07-17,Plasmon-Exciton Coupling Effect on Plasmon Damping,"Plasmon decay via the surface or interface is a critical process for
practical energy conversion and plasmonic catalysis. However, the relationship
between plasmon damping and the coupling between the plasmon and 2D materials
is still unclear. The spectral splitting due to plasmon-exciton interaction
impedes the conventional single-particle method to evaluate the plasmon damping
rate by the spectral linewidth directly. Here, we investigated the interaction
between a single gold nanorod (GNR) and 2D materials using the single-particle
spectroscopy method assisted with in situ nanomanipulation technique by
comparing scattering intensity and linewidth together. Our approach allows us
to indisputably identify that the plasmon-exciton coupling in the GNR-WSe2
hybrid would induce plasmon damping. We can also isolate the contribution
between the charge transfer channel and resonant energy transfer channel for
the plasmon decay in the GNR-graphene hybrid by comparing that with thin hBN
layers as an intermediate medium to block the charge transfer. We find out that
the contact layer between the GNR and 2D materials contributes most of the
interfacial plasmon damping. These findings contribute to a deep understanding
of interfacial excitonic effects on the plasmon and 2D materials hybrid.",2107.08230v1
2021-10-12,Outflows in the presence of cosmic rays and waves with cooling,"Plasma outflow from a gravitational potential well with cosmic rays and
self-excited Alfv\'en waves with cooling and wave damping is studied in the
hydrodynamics regime. We study outflows in the presence of cosmic ray and
Alfv\'en waves including the effect of cooling and wave damping. We seek
physically allowable steady-state subsonic-supersonic transonic solutions. We
adopted a multi-fluid hydrodynamical model for the cosmic ray plasma system.
Thermal plasma, cosmic rays, and self-excited Alfv\'en waves are treated as
fluids. Interactions such as cosmic-ray streaming instability, cooling, and
wave damping were fully taken into account. We considered one-dimensional
geometry and explored steady-state solutions. The model is reduced to a set of
ordinary differential equations, which we solved for subsonic-supersonic
transonic solutions with given boundary conditions at the base of the
gravitational potential well. We find that physically allowable
subsonic-supersonic transonic solutions exist for a wide range of parameters.
We studied the three-fluid system (considering only forward-propagating
Alfv\'en waves) in detail. We examined the cases with and without cosmic ray
diffusion separately. Comparisons of solutions with and without cooling and
with and without wave damping for the same set of boundary conditions (on
density, pressures of thermal gas, cosmic rays and waves) are presented. We
also present the interesting case of a four-fluid system (both forward- and
backward-propagating Alfv\'en waves are included), highlighting the intriguing
relation between different components.",2110.06170v1
2021-11-19,Finite time extinction for a class of damped Schr{ö}dinger equations with a singular saturated nonlinearity,"We present some sharper finite extinction time results for solutions of a
class of damped nonlinear Schr{\""o}dinger equations when the nonlinear damping
term corresponds to the limit cases of some ``saturating non-Kerr law''
$F(|u|^2)u=\frac{a}{\varepsilon+(|u|^2)^\alpha}u,$ with $a\in\mathbb{C},$
$\varepsilon\geqslant0,$ $2\alpha=(1-m)$ and $m\in[0,1).$ To carry out the
improvement of previous results in the literature we present in this paper a
careful revision of the existence and regularity of weak solutions under very
general assumptions on the data. We prove that the problem can be solved in the
very general framework of the maximal monotone operators theory, even under a
lack of regularity of the damping term. This allows us to consider, among other
things, the singular case $m=0.$ We replace the above approximation of the
damping term by a different one which keeps the monotonicity for any
$\varepsilon\geqslant0$. We prove that, when $m=0,$ the finite extinction time
of the solution arises for merely bounded right hand side data $f(t,x).$ This
is specially useful in the applications in which the Schr{\""o}dinger equation
is coupled with some other functions satisfying some additional equations.",2111.10136v2
2022-01-26,Effect of Chiral Damping on the dynamics of chiral domain walls and skyrmions,"Friction plays an essential role in most physical processes that we
experience in our everyday life. Examples range from our ability to walk or
swim, to setting boundaries of speed and fuel efficiency of moving vehicles. In
magnetic systems, the displacement of chiral domain walls (DW) and skyrmions
(SK) by Spin Orbit Torques (SOT), is also prone to friction. Chiral damping,
the dissipative counterpart of the Dzyaloshinskii Moriya Interaction (DMI),
plays a central role in these dynamics. Despite experimental observation, and
numerous theoretical studies confirming its existence, the influence of chiral
damping on DW and SK dynamics has remained elusive due to the difficulty of
discriminating from DMI. Here we unveil the effect that chiral damping has on
the flow motion of DWs and SKs driven by current and magnetic field. We use a
static in-plane field to lift the chiral degeneracy. As the in-plane field is
increased, the chiral asymmetry changes sign. When considered separately,
neither DMI nor chiral damping can explain the sign reversal of the asymmetry,
which we prove to be the result of their competing effects. Finally, numerical
modelling unveils the non-linear nature of chiral dissipation and its critical
role for the stabilization of moving SKs.",2201.10742v1
2022-01-27,A Study on Monte Carlo simulation of the radiation environment above GeV at the DAMPE orbit,"The Dark Matter Particle Explorer (DAMPE) has been undergoing a stable
on-orbit operation for more than 6 years and acquired observation of over 11
billion events. And a better understanding of the overall radiation environment
on the DAMPE orbit is crucial for both simulation data production and flight
data analysis. In this work, we study the radiation environment at the low
Earth orbit and develop a simulation software package using the framework of
ATMNC3, in which state-of-the-art full 3D models of the Earth's atmospheric and
magnetic-field configurations is integrated. We consider in our Monte Carlo
procedure event-by-event propagation of the cosmic rays in the geomagnetic
field and their interaction with the Earth's atmosphere, focusing on the
particles above GeV that are able to trigger the DAMPE data acquisition system.
We compare the simulation results with the cosmic-ray electrons and positrons
(CREs) flux measurements made by DAMPE. The overall agreement on both the
spectral and angular distribution of the CREs flux demonstrates that our
simulation is well established. Our software package could be of more general
usage for the simulation of the radiation environment at the low Earth orbit of
various altitudes.",2201.11364v1
2022-05-10,Nonlinear damping quantification from phase-resonant tests under base excitation,"The present work addresses the experimental identification of
amplitude-dependent modal parameters (modal frequency, damping ratio, Fourier
coefficients of periodic modal oscillation). Phase-resonant testing has emerged
as an important method for this task, as it substantially reduces the amount of
data required for the identification compared to conventional
frequency-response testing at different excitation/response levels. In the case
of shaker-stinger excitation, the applied excitation force is commonly measured
in order to quantify the amplitude-dependent modal damping ratio from the
phase-resonant test data. In the case of base excitation, however, the applied
excitation force is challenging or impossible to measure. In this work we
develop an original method for damping quantification from phase-resonant
tests. It relies solely on response measurement; it avoids the need to resort
to force measurement. The key idea is to estimate the power provided by the
distributed inertia force imposed by the base motion. We develop both a
model-free and a model-based variant of the method. We validate the developed
method first in virtual experiments of a friction-damped and a geometrically
nonlinear system, and then in a physical experiment involving a thin beam
clamped at both ends via bolted joints. We conclude that the method is highly
robust and provides high accuracy already for a reasonable number of sensors.",2205.04735v1
2022-06-08,Motion control with optimal nonlinear damping: from theory to experiment,"Optimal nonlinear damping control was recently introduced for the
second-order SISO systems, showing some advantages over a classical PD feedback
controller. This paper summarizes the main theoretical developments and
properties of the optimal nonlinear damping controller and demonstrates, for
the first time, its practical experimental evaluation. An extended analysis and
application to more realistic (than solely the double-integrator) motion
systems are also given in the theoretical part of the paper. As comparative
linear feedback controller, a PD one is taken, with the single tunable gain and
direct compensation of the plant time constant. The second, namely
experimental, part of the paper includes the voice-coil drive system with
relatively high level of the process and measurement noise, for which the
standard linear model is first identified in frequency domain. The linear
approximation by two-parameters model forms the basis for designing the PD
reference controller, which fixed feedback gain is the same as for the optimal
nonlinear damping control. A robust sliding-mode based differentiator is used
in both controllers for a reliable velocity estimation required for the
feedback. The reference PD and the proposed optimal nonlinear damping
controller, both with the same single design parameter, are compared
experimentally with respect to trajectory tracking and disturbance rejection.",2206.03802v2
2022-09-22,Neutrino Fast Flavor Pendulum. Part 2: Collisional Damping,"In compact astrophysical objects, the neutrino density can be so high that
neutrino-neutrino refraction can lead to fast flavor conversion of the kind
$\nu_e \bar\nu_e \leftrightarrow \nu_x \bar\nu_x$ with $x=\mu,\tau$, depending
on the neutrino angle distribution. Previously, we have shown that in a
homogeneous, axisymmetric two-flavor system, these collective solutions evolve
in analogy to a gyroscopic pendulum. In flavor space, its deviation from the
weak-interaction direction is quantified by a variable $\cos\vartheta$ that
moves between $+1$ and $\cos\vartheta_{\rm min}$, the latter following from a
linear mode analysis. As a next step, we include collisional damping of flavor
coherence, assuming a common damping rate $\Gamma$ for all modes. Empirically
we find that the damped pendular motion reaches an asymptotic level of pair
conversion $f=A+(1-A)\cos\vartheta_{\rm min}$ (numerically $A\simeq 0.370$)
that does not depend on details of the angular distribution (except for fixing
$\cos\vartheta_{\rm min}$), the initial seed, nor $\Gamma$. On the other hand,
even a small asymmetry between the neutrino and antineutrino damping rates
strongly changes this picture and can even enable flavor instabilities in
otherwise stable systems.",2209.11235v3
2022-10-12,Second order two-species systems with nonlocal interactions: existence and large damping limits,"We study the mathematical theory of second order systems with two species,
arising in the dynamics of interacting particles subject to linear damping, to
nonlocal forces and to external ones, and resulting into a nonlocal version of
the compressible Euler system with linear damping. Our results are limited to
the $1$ space dimensional case but allow for initial data taken in a
Wasserstein space of probability measures. We first consider the case of smooth
nonlocal interaction potentials, not subject to any symmetry condition, and
prove existence and uniqueness. The concept of solutions relies on a stickiness
condition in case of collisions, in the spirit of previous works in the
literature. The result uses concepts from classical Hilbert space theory of
gradient flows (cf. Brezis [7]) and a trick used in [4]. We then consider a
large-time and large-damping scaled version of our system and prove convergence
to solutions to the corresponding first order system. Finally, we consider the
case of Newtonian potentials -- subject to symmetry of the cross-interaction
potentials -- and external convex potentials. After showing existence in the
sticky particles framework in the spirit of [4], we prove convergence for large
times towards Dirac delta solutions for the two densities. All the results
share a common technical framework in that solutions are considered in a
Lagrangian framework, which allows to estimate the behavior of solutions via
$L^2$ estimates of the pseudo-inverse variables corresponding to the two
densities. In particular, due to this technique, the large-damping result holds
under a rather weak condition on the initial data, which does not require
well-prepared initial velocities. We complement the results with numerical
simulations.",2210.06162v1
2022-10-12,Stability of the Néel quantum critical point in the presence of Dirac fermions,"We investigate the stability of the N\'eel quantum critical point of
two-dimensional quantum antiferromagnets, described by a non-linear $\sigma$
model (NL$\sigma$M), in the presence of a Kondo coupling to $N_f$ flavours of
two-component Dirac fermion fields. The long-wavelength order parameter
fluctuations are subject to Landau damping by electronic particle-hole
fluctuations. Using momentum-shell RG, we demonstrate that the Landau damping
is weakly irrelevant at the N\'eel quantum critical point, despite the fact
that the corresponding self-energy correction dominates over the quadratic
gradient terms in the IR limit. In the ordered phase, the Landau damping
increases under the RG, indicative of damped spin-wave excitations. Although
the Kondo coupling is weakly relevant, sufficiently strong Landau damping
renders the N\'eel quantum critical point quasi-stable for $N_f\ge 4$ and
thermodynamically stable for $N_f<4$. In the latter case, we identify a new
multi-critical point which describes the transition between the N\'eel critical
and Kondo run-away regimes. The symmetry breaking at this fixed point results
in the opening of a gap in the Dirac fermion spectrum. Approaching the
multi-critical point from the disordered phase, the fermionic quasiparticle
residue vanishes, giving rise to non-Fermi-liquid behavior.",2210.06577v3
2022-11-13,Damping analysis of Floating Offshore Wind Turbine (FOWT): a new control strategy reducing the platform vibrations,"In this paper, the coupled dynamics of the floating platform and the WTG
rotor is analysed. In particular, the damping is explicitly derived from the
coupled equations of rotor and floating platform. The analysis of the damping
leads to the study of the instability phenomena and it derives the explicit
conditions that lead to the Non Minimum Phase Zero (NMPZ). Two NMPZs, one
related to the rotor dynamics and the other one to the platform pitch dynamics,
are analysed. The latter is a novelty and it is analysed in this work,
providing the community of an explicit condition for its verification. The
domain of the instability of the platform is explicitly derived from the
coupled system of equations. In the second part of the paper, from the analysis
of the damping of the floating platform, a new strategy for the control of
FOWTs is proposed. This strategy allows one to impose to the controller an
explicit level of damping in the platform pitch motion without changing the
period of platform pitching. Finally the new strategy is compared to the one
without compensation by performing aero-hydro-servo-elastic numerical
simulations of the UMaine IEA15MW FOWT. Generated power, movements, blade pitch
and tower base fatigue are compared showing that the new control strategy can
reduce fatigue in the structure without affecting the power production.",2211.10362v1
2022-11-22,Universal Dynamics of Damped-Driven Systems: The Logistic Map as a Normal Form for Energy Balance,"Damped-driven systems are ubiquitous in engineering and science. Despite the
diversity of physical processes observed in a broad range of applications, the
underlying instabilities observed in practice have a universal characterization
which is determined by the overall gain and loss curves of a given system. The
universal behavior of damped-driven systems can be understood from a
geometrical description of the energy balance with a minimal number of
assumptions. The assumptions on the energy dynamics are as follows: the energy
increases monotonically as a function of increasing gain, and the losses become
increasingly larger with increasing energy, i.e. there are many routes for
dissipation in the system for large input energy. The intersection of the gain
and loss curves define an energy balanced solution. By constructing an
iterative map between the loss and gain curves, the dynamics can be shown to be
homeomorphic to the logistic map, which exhibits a period doubling cascade to
chaos. Indeed, the loss and gain curves allow for a geometrical description of
the dynamics through a simple Verhulst diagram (cobweb plot). Thus irrespective
of the physics and its complexities, this simple geometrical description
dictates the universal set of logistic map instabilities that arise in complex
damped-driven systems. More broadly, damped-driven systems are a class of
non-equilibrium pattern forming systems which have a canonical set of
instabilities that are manifest in practice.",2211.11748v1
2023-01-23,Optimal Inter-area Oscillation Damping Control: A Transfer Deep Reinforcement Learning Approach with Switching Control Strategy,"Wide-area damping control for inter-area oscillation (IAO) is critical to
modern power systems. The recent breakthroughs in deep learning and the broad
deployment of phasor measurement units (PMU) promote the development of
datadriven IAO damping controllers. In this paper, the damping control of IAOs
is modeled as a Markov Decision Process (MDP) and solved by the proposed Deep
Deterministic Policy Gradient (DDPG) based deep reinforcement learning (DRL)
approach. The proposed approach optimizes the eigenvalue distribution of the
system, which determines the IAO modes in nature. The eigenvalues are evaluated
by the data-driven method called dynamic mode decomposition. For a given power
system, only a subset of generators selected by participation factors needs to
be controlled, alleviating the control and computing burdens. A Switching
Control Strategy (SCS) is introduced to improve the transient response of IAOs.
Numerical simulations of the IEEE-39 New England power grid model validate the
effectiveness and advanced performance of the proposed approach as well as its
robustness against communication delays. In addition, we demonstrate the
transfer ability of the DRL model trained on the linearized power grid model to
provide effective IAO damping control in the non-linear power grid model
environment.",2301.09321v1
2023-03-15,Blow-up and decay for a class of variable coefficient wave equation with nonlinear damping and logarithmic source,"In this paper, we consider the long time behavior for the solution of a class
of variable coefficient wave equation with nonlinear damping and logarithmic
source. The existence and uniqueness of local weak solution can be obtained by
using the Galerkin method and contraction mapping principle. However, the long
time behavior of the solution is usually complicated and it depends on the
balance mechanism between the damping and source terms. When the damping
exponent $(p+1)$ (see assumption (H3)) is greater than the source term exponent
$(q-1)$ (see equation (1.1)), namely, $p+2>q$, we obtain the global existence
and accurate decay rates of the energy for the weak solutions with any initial
data. Moreover, whether the weak solution exists globally or blows up in finite
time, it is closely related to the initial data. In the framework of modified
potential well theory, we construct the stable and unstable sets (see (2.8))
for the initial data. For the initial data belonging to the stable set, we
prove that the weak solution exists globally and has similar decay rates as the
previous results. For $p+2<q$ and the initial data belonging to the unstable
set, we prove that the weak solution blows up in finite time for a little
special damping $g(u_{t})=|u_{t}|^{p}u_{t}$.",2303.08629v1
2023-04-13,Centralised Multimode Power Oscillation Damping Controller for Photovoltaic Plants with Communication Delay Compensation,"Low-frequency oscillations are an inherent phenomena in transmission networks
and renewable energy plants should be configured to damp them. Commonly, a
centralised controller is used in PV plants to coordinate PV generators via
communication channels. However, the communication systems of PV plants
introduce delays of a stochastic nature that degrade the performance of
centralised control algorithms. Therefore, controllers for oscillation damping
may not operate correctly unless the communication channel characteristics are
not considered and compensated. In this paper, a centralised controller is
proposed for the oscillation damping that uses a PV plant with all the
realistic effects of communication channels taken into consideration. The
communication channels are modelled based on measurements taken in a laboratory
environment. The controller is designed to damp several modes of oscillation by
using the open-loop phase shift compensation. Theoretical developments were
validated in a laboratory using four converters acting as two PV inverters, a
battery and a STATCOM. A real-time processing platform was used to implement
the centralised controller and to deploy the communication infrastructure.
Experimental results show the communication channels impose severe restrictions
on the performance of centralised POD controllers, highlighting the importance
of their accurate modelling and consideration during the controller design
stage.",2304.06415v1
2023-05-09,Glassy heat capacity from overdamped phasons and a hypothetical phason-induced superconductivity in incommensurate structures,"Phasons are collective low-energy modes that appear in disparate condensed
matter systems such as quasicrystals, incommensurate structures, fluctuating
charge density waves, and Moir\'e superlattices. They share several
similarities with acoustic phonon modes, but they are not protected by any
exact translational symmetry. As a consequence, they are subject to a
wavevector independent damping, and they develop a finite pinning frequency,
which destroy their acoustic linearly propagating dispersion. Under a few and
simple well-motivated assumptions, we compute the phason density of states, and
we derive the phason heat capacity as a function of the temperature. Finally,
imagining a hypothetical s-wave pairing channel with electrons, we compute the
critical temperature $T_c$ of the corresponding superconducting state as a
function of phason damping using the Eliashberg formalism. We find that for
large phason damping, the heat capacity is linear in temperature, showing a
distinctive glass-like behavior. Additionally, we observe that the phason
damping can strongly enhance the effective Eliashberg coupling, and we reveal a
sharp non-monotonic dependence of the superconducting temperature $T_c$ on the
phason damping, with a maximum located at the underdamped to overdamped
crossover scale. Our simple computations confirm the potential role of
overdamped modes in explaining the glassy properties of incommensurate
structures, but also in possibly inducing strongly-coupled superconductivity
therein, and enhancing the corresponding $T_c$.",2305.05407v2
2023-07-12,Exponential stability of damped Euler-Bernoulli beam controlled by boundary springs and dampers,"In this paper, the vibration model of an elastic beam, governed by the damped
Euler-Bernoulli equation
$\rho(x)u_{tt}+\mu(x)u_{t}$$+\left(r(x)u_{xx}\right)_{xx}=0$, subject to the
clamped boundary conditions $u(0,t)=u_x(0,t)=0$ at $x=0$, and the boundary
conditions $\left(-r(x)u_{xx}\right)_{x=\ell}=k_r u_x(\ell,t)+k_a
u_{xt}(\ell,t)$, $\left(-\left(r(x)u_{xx}\right)_{x}\right )_{x=\ell}$$=- k_d
u(\ell,t)-k_v u_{t}(\ell,t)$ at $x=\ell$, is analyzed. The boundary conditions
at $x=\ell$ correspond to linear combinations of damping moments caused by
rotation and angular velocity and also, of forces caused by displacement and
velocity, respectively. The system stability analysis based on well-known
Lyapunov approach is developed. Under the natural assumptions guaranteeing the
existence of a regular weak solution, uniform exponential decay estimate for
the energy of the system is derived. The decay rate constant in this estimate
depends only on the physical and geometric parameters of the beam, including
the viscous external damping coefficient $\mu(x) \ge 0$, and the boundary
springs $k_r,k_d \ge 0$ and dampers $k_a,k_v \ge 0$. Some numerical examples
are given to illustrate the role of the damping coefficient and the boundary
dampers.",2307.06170v2
2023-08-03,Flavor-wave theory with quasiparticle damping at finite temperatures: Application to chiral edge modes in the Kitaev model,"We propose a theoretical framework to investigate elementary excitations at
finite temperatures within a localized electron model that describes the
interactions between multiple degrees of freedom, such as quantum spin models
and Kugel-Khomskii models. Thus far, their excitation structures have been
mainly examined using the linear flavor-wave theory, an SU($N$) generalization
of the linear spin-wave theory. These techniques introduce noninteracting
bosonic quasiparticles as elementary excitations from the ground state, thereby
elucidating numerous physical phenomena, including excitation spectra and
transport properties characterized by topologically nontrivial band structures.
Nevertheless, the interactions between quasiparticles cannot be ignored in
systems exemplified by $S=1/2$ quantum spin models, where strong quantum
fluctuations are present. Recent studies have investigated the effects of
quasiparticle damping at zero temperature in such models. In our study,
extending this approach to the flavor-wave theory for general localized
electron models, we construct a comprehensive method to calculate excitation
spectra with the quasiparticle damping at finite temperatures. We apply our
method to the Kitaev model under magnetic fields, a typical example of models
with topologically nontrivial magnon bands. Our calculations reveal that chiral
edge modes undergo significant damping in weak magnetic fields, amplifying the
damping rate by the temperature increase. This effect is caused by collisions
with thermally excited quasiparticles. Since our approach starts from a general
Hamiltonian, it will be widely applicable to other localized systems, such as
spin-orbital coupled systems derived from multi-orbital Hubbard models in the
strong correlation limit.",2308.01711v1
2024-02-13,Investigating the Effect of Noise on the Training Performance of Hybrid Quantum Neural Networks,"In this paper, we conduct a comprehensively analyze the influence of
different quantum noise gates, including Phase Flip, Bit Flip, Phase Damping,
Amplitude Damping, and the Depolarizing Channel, on the performance of HyQNNs.
Our results reveal distinct and significant effects on HyQNNs training and
validation accuracies across different probabilities of noise. For instance,
the Phase Flip gate introduces phase errors, and we observe that HyQNNs exhibit
resilience at higher probability (p = 1.0), adapting effectively to consistent
noise patterns, whereas at intermediate probabilities, the performance
declines. Bit Flip errors, represented by the PauliX gate, impact HyQNNs in a
similar way to that Phase Flip error gate. The HyQNNs, can adapt such kind of
errors at maximum probability (p = 1.0). Unlike Phase and Bit Flip error gates,
Phase Damping and Amplitude Damping gates disrupt quantum information, with
HyQNNs demonstrating resilience at lower probabilities but facing challenges at
higher probabilities. Amplitude Damping error gate, in particular, poses
efficiency and accuracy issues at higher probabilities however with lowest
probability (p = 0.1),it has the least effect and the HyQNNs, however not very
effectively, but still tends to learn. The Depolarizing Channel proves most
detrimental to HyQNNs performance, with limited or no training improvements.
There was no training potential observed regardless of the probability of this
noise gate. These findings underscore the critical need for advanced quantum
error mitigation and resilience strategies in the design and training of
HyQNNs, especially in environments prone to depolarizing noise. This paper
quantitatively investigate that understanding the impact of quantum noise gates
is essential for harnessing the full potential of quantum computing in
practical applications.",2402.08523v1
2024-03-03,Magnonic $\varphi$ Josephson Junctions and Synchronized Precession,"There has been a growing interest in non-Hermitian physics. One of its main
goals is to engineer dissipation and to explore ensuing functionality. In
magnonics, the effect of dissipation due to local damping on magnon transport
has been explored. However, the effects of non-local damping on the magnonic
analog of the Josephson effect remain missing, despite that non-local damping
is inevitable and has been playing a central role in magnonics. Here, we
uncover theoretically that a surprisingly rich dynamics can emerge in magnetic
junctions due to intrinsic non-local damping, using analytical and numerical
methods. In particular, under microwave pumping, we show that coherent spin
precession in the right and left insulating ferromagnet (FM) of the junction
becomes synchronized by non-local damping and thereby a magnonic analog of the
$\varphi$ Josephson junction emerges, where $\varphi$ stands here for the
relative precession phase of right and left FM in the stationary limit.
Remarkably, $\varphi$ decreases monotonically from $ \pi$ to $\pi/2$ as the
magnon-magnon interaction, arising from spin anisotropies, increases. Moreover,
we also find a magnonic diode effect giving rise to rectification of magnon
currents. Our predictions are readily testable with current device and
measurement technologies at room temperatures.",2403.01625v1
2017-02-08,Resolution of two fundamental issues in the dynamics of relativity and exposure of a real version of the emperor's new clothes,"In this paper, we aim to resolve two fundamental issues in the dynamics of
relativity: (i) Under what condition, the time-column space integrals of a
Lorentz four-tensor constitute a Lorentz four-vector, and (ii) under what
condition, the time-element space integral of a Lorentz four-vector is a
Lorentz scalar; namely two ""conservation laws"", which are mispresented in
traditional textbooks, and widely used in fundamental research, such as
relativistic analysis of the momentum of light in a medium, and the proofs of
the positive mass theorem in general relativity. To resolve issue (i), we have
developed a generalized Lorentz \emph{four-vector} theorem based on the
principles of classical mathematical analysis, with a simplified analytic
example given to illustrate how to transform a space integral from one inertial
frame to another, and a strict mathematical derivation provided to confirm the
effect of Lorentz contraction. We use this four-vector theorem to verify
M{\o}ller's theorem, and surprisingly find that M{\o}ller's theorem is
fundamentally wrong. We provide a corrected version of M{\o}ller's theorem. We
also use this four-vector theorem to analyze a plane light wave in a moving
uniform medium, and find that the momentum and energy of Minkowski quasi-photon
constitute a Lorentz four-vector and Planck constant is a Lorentz invariant. To
resolve issue (ii), we have developed a generalized Lorentz \emph{scalar}
theorem. We use this theorem to verify the ""invariant conservation law"" in
relativistic electrodynamics, and unexpectedly find that it is also
fundamentally wrong. Thus the two ""conservation laws"" in traditional textbooks,
which have magically attracted several generations of most outstanding
scientists, turned out to be imaginary, just like the emperor's new clothes;
creating a scientific myth in the modern theoretical and mathematical physics:
Believing is seeing.",1702.03200v24
2008-06-23,Cosmic Rays and the Search for a Lorentz Invariance Violation,"This is an introductory review about the on-going search for a signal of
Lorentz Invariance Violation (LIV) in cosmic rays. We first summarise basic
aspects of cosmic rays, focusing on rays of ultra high energy (UHECRs). We
discuss the Greisen-Zatsepin-Kuz'min (GZK) energy cutoff for cosmic protons,
which is predicted due to photopion production in the Cosmic Microwave
Background (CMB). This is a process of modest energy in the proton rest frame.
It can be investigated to a high precision in the laboratory, if Lorentz
transformations apply even at factors $\gamma \sim O(10^{11})$. For heavier
nuclei the energy attenuation is even faster due to photo-disintegration, again
if this process is Lorentz invariant. Hence the viability of Lorentz symmetry
up to tremendous gamma-factors - far beyond accelerator tests - is a central
issue. Next we comment on conceptual aspects of Lorentz Invariance and the
possibility of its spontaneous breaking. This could lead to slightly particle
dependent ``Maximal Attainable Velocities''. We discuss their effect in decays,
Cerenkov radiation, the GZK cutoff and neutrino oscillation in cosmic rays. We
also review the search for LIV in cosmic gamma-rays. For multi TeV gamma-rays
we possibly encounter another puzzle related to the transparency of the CMB,
similar to the GZK cutoff. The photons emitted in a Gamma Ray Burst occur at
lower energies, but their very long path provides access to information not far
from the Planck scale. No LIV has been observed so far. However, even extremely
tiny LIV effects could change the predictions for cosmic ray physics
drastically. An Appendix is devoted to the recent hypothesis by the Pierre
Auger Collaboration, which identifies nearby Active Galactic Nuclei - or
objects next to them - as probable UHECR sources.",0806.3713v2
2009-05-01,Electrodynamics with Lorentz-violating operators of arbitrary dimension,"The behavior of photons in the presence of Lorentz and CPT violation is
studied. Allowing for operators of arbitrary mass dimension, we classify all
gauge-invariant Lorentz- and CPT-violating terms in the quadratic Lagrange
density associated with the effective photon propagator. The covariant
dispersion relation is obtained, and conditions for birefringence are
discussed. We provide a complete characterization of the coefficients for
Lorentz violation for all mass dimensions via a decomposition using
spin-weighted spherical harmonics. The resulting nine independent sets of
spherical coefficients control birefringence, dispersion, and anisotropy. We
discuss the restriction of the general theory to various special models,
including among others the minimal Standard-Model Extension, the isotropic
limit, the case of vacuum propagation, the nonbirefringent limit, and the
vacuum-orthogonal model. The transformation of the spherical coefficients for
Lorentz violation between the laboratory frame and the standard Sun-centered
frame is provided. We apply the results to various astrophysical observations
and laboratory experiments. Astrophysical searches of relevance include studies
of birefringence and of dispersion. We use polarimetric and dispersive data
from gamma-ray bursts to set constraints on coefficients for Lorentz violation
involving operators of dimensions four through nine, and we describe the mixing
of polarizations induced by Lorentz and CPT violation in the cosmic-microwave
background. Laboratory searches of interest include cavity experiments. We
present the theory for searches with cavities, derive the experiment-dependent
factors for coefficients in the vacuum-orthogonal model, and predict the
corresponding frequency shift for a circular-cylindrical cavity.",0905.0031v2
2011-12-07,Inertial frames without the relativity principle,"Ever since the work of von Ignatowsky circa 1910 it has been known (if not
always widely appreciated) that the relativity principle, combined with the
basic and fundamental physical assumptions of locality, linearity, and
isotropy, leads almost uniquely to either the Lorentz transformations of
special relativity or to Galileo's transformations of classical Newtonian
mechanics. Thus, if one wishes to entertain the possibility of Lorentz symmetry
breaking within the context of the class of local physical theories, then it
seems likely that one will have to abandon (or at the very least grossly
modify) the relativity principle. Working within the framework of local
physics, we reassess the notion of spacetime transformations between inertial
frames in the absence of the relativity principle, arguing that significant and
nontrivial physics can still be extracted as long as the transformations are at
least linear. An interesting technical aspect of the analysis is that the
transformations now form a groupoid/pseudo-group --- it is this technical point
that permits one to evade the von Ignatowsky argument. Even in the absence of a
relativity principle we can nevertheless deduce clear and compelling rules for
the transformation of space and time, rules for the composition of
3-velocities, and rules for the transformation of energy and momentum. As part
of the analysis we identify two particularly elegant and physically compelling
models implementing ""minimalist"" violations of Lorentz invariance --- in the
first of these minimalist models all Lorentz violations are confined to
carefully delineated particle physics sub-sectors, while the second minimalist
Lorentz-violating model depends on one free function of absolute velocity, but
otherwise preserves as much as possible of standard Lorentz invariant physics.",1112.1466v3
2014-10-23,Cosmological constraints on deviations from Lorentz invariance in gravity and dark matter,"We consider a scenario where local Lorentz invariance is violated by the
existence of a preferred time direction at every space-time point. This
scenario can arise in the context of quantum gravity and its description at low
energies contains a unit time-like vector field which parameterizes the
preferred direction. The particle physics tests of Lorentz invariance preclude
a direct coupling of this vector to the fields of the Standard Model, but do
not bear implications for dark matter. We discuss how the presence of this
vector and its possible coupling to dark matter affect the evolution of the
Universe. At the level of homogeneous cosmology the only effect of Lorentz
invariance violation is a rescaling of the expansion rate. The physics is
richer at the level of perturbations. We identify three effects crucial for
observations: the rescaling of the matter contribution to the Poisson equation,
the appearance of an extra contribution to the anisotropic stress and the
scale-dependent enhancement of dark matter clustering. These effects result in
distinctive features in the power spectra of the CMB and density fluctuations.
Making use of the data from Planck and WiggleZ we obtain the most stringent
cosmological constraints to date on departures from Lorentz symmetry. Our
analysis provides the first direct bounds on deviations from Lorentz invariance
in the dark matter sector.",1410.6514v2
2014-12-06,A Michelson-Morley Test of Lorentz Symmetry for Electrons,"All evidence so far suggests that the absolute spatial orientation of an
experiment never affects its outcome. This is reflected in the Standard Model
of physics by requiring all particles and fields to be invariant under Lorentz
transformations. The most well-known test of this important cornerstone of
physics are Michelson-Morley-type experiments\cite{MM, Herrmann2009,Eisele2009}
verifying the isotropy of the speed of light. Lorentz symmetry also implies
that the kinetic energy of an electron should be independent of the direction
of its velocity, \textit{i.e.,} its dispersion relation should be isotropic in
space. In this work, we search for violation of Lorentz symmetry for electrons
by performing an electronic analogue of a Michelson-Morley experiment. We split
an electron-wavepacket bound inside a calcium ion into two parts with different
orientations and recombine them after a time evolution of 95ms. As the Earth
rotates, the absolute spatial orientation of the wavepackets changes and
anisotropies in the electron dispersion would modify the phase of the
interference signal. To remove noise, we prepare a pair of ions in a
decoherence-free subspace, thereby rejecting magnetic field fluctuations common
to both ions\cite{Roos2006}. After a 23 hour measurement, we limit the energy
variations to $h\times 11$ mHz ($h$ is Planck's constant), verifying that
Lorentz symmetry is preserved at the level of $1\times10^{-18}$. We improve on
the Lorentz-violation limits for the electron by two orders of
magnitude\cite{Hohensee2013c}. We can also interpret our result as testing the
rotational invariance of the Coloumb potential, improving limits on rotational
anisotropies in the speed of light by a factor of
five\cite{Herrmann2009,Eisele2009}. Our experiment demonstrates the potential
of quantum information techniques in the search for physics beyond the Standard
Model.",1412.2194v2
2015-10-24,Lorentz boosted frame simulation of Laser wakefield acceleration in quasi-3D geometry,"When modeling laser wakefield acceleration (LWFA) using the particle-in-cell
(PIC) algorithm in a Lorentz boosted frame, the plasma is drifting
relativistically at $\beta_b c$ towards the laser, which can lead to a
computational speedup of $\sim \gamma_b^2=(1-\beta_b^2)^{-1}$. Meanwhile, when
LWFA is modeled in the quasi-3D geometry in which the electromagnetic fields
and current are decomposed into a limited number of azimuthal harmonics,
speedups are achieved by modeling three dimensional problems with the
computation load on the order of two dimensional $r-z$ simulations. Here, we
describe how to combine the speed ups from the Lorentz boosted frame and
quasi-3D algorithms. The key to the combination is the use of a hybrid Yee-FFT
solver in the quasi-3D geometry that can be used to effectively eliminate the
Numerical Cerenkov Instability (NCI) that inevitably arises in a Lorentz
boosted frame due to the unphysical coupling of Langmuir modes and EM modes of
the relativistically drifting plasma in these simulations. In addition, based
on the space-time distribution of the LWFA data in the lab and boosted frame,
we propose to use a moving window to follow the drifting plasma to further
reduce the computational load. We describe the details of how the NCI is
eliminated for the quasi-3D geometry, the setups for simulations which combine
the Lorentz boosted frame and quasi-3D geometry, the use of a moving window,
and compare the results from these simulations against their corresponding lab
frame cases. Good agreement is obtained, particularly when there is no
self-trapping, which demonstrates it is possible to combine the Lorentz boosted
frame and the quasi-3D algorithms when modeling LWFA to achieve unprecedented
speedups.",1510.07110v1
2021-12-01,Symmetries and Conservation Laws in Horava Gravity,"Horava gravity has been proposed as a renormalizable quantum gravity without
the ghost problem through anisotropic scaling dimensions which break Lorentz
symmetry in UV. In the Hamiltonian formalism, due to the Lorentz-violating
terms, the constraint structure looks quite different from that of general
relativity (GR) but we have recently found that ""there exists the case where we
can recover the same number of degrees of freedom as in GR"", in a rather
general set-up. In this paper, we study its Lagrangian perspectives and examine
the full diffeomorphism (Diff) symmetry and its associated conservation laws in
Horava gravity. Surprisingly, we find that the full Diff symmetry in the action
can also be recovered when a certain condition, called ""super-condition"", which
super-selects the Lorentz-symmetric sector in Horava gravity, is satisfied.
This indicates that the broken Lorentz symmetry, known as
""foliation-preserving"" Diff, is just an ""apparent"" symmetry of the Horava
gravity action and rather its ""full action symmetry can be as large as the Diff
in GR "". The super-condition exactly corresponds to the tertiary constraint in
Hamiltonian formalism which is the second-class constraint and provides a
non-trivial realization of the Lorentz symmetry otherwise being absent
apparently. From the recovered Lorentz symmetry in the action, we obtain the
conservation laws with the Noether currents as in covariant theories. The
general formula for the conserved Noether charges reproduces the mass of
four-dimensional static black holes with an ""arbitrary"" cosmological constant
in Horava gravity, and is independent of ambiguities associated with the choice
of asymptotic boundaries. We also discuss several challenging problems,
including its implications to Hamiltonian formalism, black hole thermodynamics,
radiations from colliding black holes.",2112.00576v3
2021-12-13,Gravitational wave constraints on Lorentz and parity violations in gravity: high-order spatial derivative cases,"High-order spatial derivatives are of crucial importance for constructing the
low energy effective action of a Lorentz or parity violating theory of quantum
gravity. One example is the Ho\v{r}ava-Lifshitz gravity, in one has to consider
at least the sixth-order spatial derivatives in the gravitational action, in
order to make the theory power-counting renormalizable. In this paper, we
consider the Lorentz and parity violating effects on the propagation of GWs due
to the fifth and sixth-order spatial derivatives respectively. For this purpose
we calculate the corresponding Lorentz and parity violating waveforms of GWs
produced by the coalescence of compact binaries. By using these modified
waveforms, we perform the full Bayesian inference with the help of the open
source software \texttt{Bilby} on the selected GW events of binary black hole
(BBH) and binary neutron stars (BNS) merges in the LIGO-Virgo catalogs GWTC-1
and GWTC-2. Overall we do not find any significant evidence of Lorentz and
parity violation due to the fifth and sixth-order spatial derivatives and thus
place lower bounds on the energy scales $M_{\rm LV} > 2.4 \times 10^{-16} \;
{\rm GeV}$ for Lorentz violation and $M_{\rm PV} > 1.0 \times 10^{-14} \; {\rm
GeV}$ for parity violation at 90\% confidence level. Both constraints represent
the first constraints on the fifth- and sixth-order spatial derivative terms
respectively in the framework of spatial covariant gravity by using the
observational data of GWs.",2112.06446v2
1997-01-17,Evidence for Rotation in the Galaxy at z=3.15 Responsible for a Damped Lyman-alpha Absorption System in the Spectrum of Q2233+1310,"Proof of the existence of a significant population of normal disk galaxies at
redshift z>2 would have profound implications for theories of structure
formation and evolution. We present evidence based on Keck HIRES observations
that the damped Lyman-alpha absorber at z=3.15 toward the quasar Q2233+1310 may
well be such an example. Djorgovski et al have recently detected the
Lyman-alpha emission from the absorber, which we assume is at the systemic
redshift of the absorbing galaxy. By examining the profiles of the metal
absorption lines arising from the absorbing galaxy in relation to its systemic
redshift, we find strong kinematical evidence for rotation. Therefore the
absorber is likely to be a disk galaxy. The inferred circular velocity for the
galaxy is >200 km/s. With a separation of ~17 kpc between the galaxy and the
quasar sightline, the implied dynamic mass for the galaxy is >1.6x10(11) solar
mass. The metallicity of the galaxy is found to be [Fe/H]=-1.4, typical of
damped Lyman-alpha galaxies at such redshifts. However, in another damped
galactic rotation is evident. In the latter case, the damped Lyman-alpha
absorber occurs near the background quasar in redshift so its properties may be
influenced by the background quasar. These represent the only two cases at
present for which the technique used here may be applied. Future applications
of the same technique to a large sample of damped Lyman-alpha galaxies may
allow us to determine if a significant population of disk galaxies already
existed only a few billion years after the Big Bang.",9701116v2
1997-04-11,The Metallicity of High Redshift Galaxies: The Abundance of Zinc in 34 Damped Lyman Alpha Systems from z = 0.7 to 3.4,"We report new observations of ZnII and CrII absorption lines in 10 damped
\lya systems (DLAs), mostly at redshift $z_{abs} \simgt 2.5$ . By combining
these results with those from our earlier survey (Pettini et al. 1994) and
other recent data, we construct a sample of 34 measurements (or upper limits)
of the Zn abundance relative to hydrogen [Zn/H]; the sample includes more than
one third of the total number of DLAs known.
  The plot of the abundance of Zn as a function of redshift reinforces the two
main findings of our previous study. (1) Damped \lya systems are mostly
metal-poor, at all redshifts sampled; the column density weighted mean for the
whole data set is [Zn/H] $= -1.13 \pm 0.38$ (on a logarithmic scale), or
approximately 1/13 of solar. (2) There is a large spread, by up to two orders
of magnitude, in the metallicities we measure at essentially the same
redshifts. We propose that damped \lya systems are drawn from a varied
population of galaxies of different morphological types and at different stages
of chemical evolution, supporting the idea of a protracted epoch of galaxy
formation.
  At redshifts $z \simgt 2$ the typical metallicity of the damped \lya systems
is in agreement with expectations based on the consumption of HI gas implied by
the recent measurements of $\Omega_{DLA}$ by Storrie-Lombardi et al. (1996a),
and with the metal ejection rates in the universe at these epochs deduced by
Madau (1996) from the ultraviolet luminosities of high redshift galaxies
revealed by deep imaging surveys. There are indications in our data for an
increase in the mean metallicity of the damped \lya systems from $z > 3$ to
$\approx 2$, consistent with the rise in the comoving star formation rate
indicated by the relative numbers of $U$ and $B$ drop-outs in the Hubble Deep
Field. Although such comparisons are still tentative, it appears that these
different avenues for exploring the early evolution of galaxies give a broadly
consistent picture.",9704102v1
1997-04-17,On the Kinematics of the Damped Lyman Alpha Protogalaxies,"We present the first results of an ongoing program to investigate the
kinematic characteristics of high redshift damped lya systems. Because damped
lya systems are widely believed to be the progenitors of current massive
galaxies, an analysis of their kinematic history allows a direct test of galaxy
formation scenarios.
  We have collected a kinematically unbiased sample of 17 high S/N ratio, high
resolution damped lya spectra taken with HIRES on the 10m W.M. Keck Telescope.
Our study focuses on the unsaturated, low-ion transitions of these systems
which reveal their kinematic traits. The profiles exhibit a nearly uniform
distribution of velocity widths ranging from 20 - 200 km/s and a relatively
high degree of asymmetry. In an attempt to explain these characteristics, we
introduce several physical models, which have previously been attributed to
damped lya systems, including rapidly rotating cold disks, slowly rotating hot
disks, massive isothermal halos, and a hydrodynamic spherical accretion model.
  Using standard Monte Carlo techniques, we run sightlines through these model
systems to derive simulated low-ion profiles. Comparing statistical measures of
the simulated profiles with the observed profiles, we determine that the
rapidly rotating cold disk model is the only tested model consistent with the
data at high confidence levels. A Relative Likelihood Test of the rapidly
rotating cold disk model indicates the disks must have large rotation speeds; v
> 180 km/s at the 99% c.l. In turn, we demonstrate that the Cold Dark Matter
Model, as developed by Kauffmann (1996), is inconsistent with the damped lya
data at very high c.l. This is because the CDM Model does not predict a large
enough fraction of rapidly rotating disks at z approx 2.5.",9704169v2
2000-11-20,H-alpha Imaging with HST+NICMOS of An Elusive Damped Ly-alpha Cloud at z=0.6,"Despite previous intensive ground-based imaging and spectroscopic campaigns
and wide-band HST imaging of the z=0.927 QSO 3C336 field, the galaxy that hosts
the damped Ly-alpha system along this line-of-sight has eluded detection. We
present a deep narrow-band H-alpha image of the field of this z=0.656 damped
Ly-alpha absorber, obtained through the F108N filter of NICMOS 1 onboard the
Hubble Space Telescope. The goal of this project was to detect any H-alpha
emission 10 times closer than previous studies to unveil the damped absorber.
We do not detect H-alpha emission between 0.05'' and 6'' (0.24 and 30 $h^{-1}$
kpc) from the QSO, with a 3-sigma flux limit of $3.70 \times 10^{-17} h^{-2}$
erg/s/cm^2 for an unresolved source, corresponding to a star formation rate
(SFR) of $0.3 h^{-2}$ M_sun/yr. This leads to a 3-sigma upper limit of 0.15
M_sun/yr/kpc^2 on the SFR density, or a maximum SFR of 1.87 M_sun/yr assuming a
disk of 4 kpc in diameter. This result adds to the number of low redshift
damped Ly-alpha absorbers that are not associated with the central regions of
Milky-Way-like disks. Damped Ly-alpha absorption can arise from high density
concentrations in a variety of galactic environments including some that,
despite their high local HI densities, are not conducive to widespread star
formation.",0011374v2
2005-08-17,The SDSS Damped Lya Survey: Data Release 3,"We present the results from a damped Lya survey of the Sloan Digital Sky
Survey, Data Release 3 based on over 500 new damped Lya systems at z>2.2. We
measure the HI column density distribution f(N) and its zeroth and first
moments (the incidence l(X) and gas mass-density O_dla of damped Lya systems,
respectively) as a function of redshift. The key results include: (1) the f(N)
distribution is well fit by a Gamma-function with `break' column density log
N_g=10^21.5 and `faint-end' slope alpha=-1.8; (2) the shape of the f(N)
distributions do not show evolution with redshift; (3) l(X) and O_dla decrease
by 35% and 50% during ~1Gyr between redshift z=[3.,3.5] to z=[2.2,2.5]; and (4)
l(X) and O_dla in the lowest SDSS redshift bin (z=2.2) are consistent with the
current values. We investigate systematic errors in damped Lya analysis and
identify only one important effect: we measure 40 +/- 20% higher O_dla values
toward a subset of brighter quasars than toward a faint subset. This effect
runs contrary to the bias associated with dust obscuration and suggests that
gravitational lensing may be important. Comparing the results against models of
galaxy formation, we find all of the models significantly underpredict l(X) at
z=3 and only SPH models with significant feedback may reproduce O_dla at high
redshift. We argue that the Lyman limit systems contribute ~1/3 of the
universe's HI atoms at all redshifts z=2 to 5 and that the f(N) distribution
for N(HI)<10^20 has an inflection with slope >-1. We advocate a new mass
density definition -- the mass density of predominantly neutral gas O_neut --
to be contrasted with the mass density of gas associated with HI atoms. We
contend the damped Lya systems contribute >80% of O_neut at all redshifts and
therefore are the main reservoirs for star formation. [abridged]",0508361v1
2010-03-11,Damping of MHD turbulence in partially ionized gas and the observed difference of velocities of neutrals and ions,"Theoretical and observational studies on the turbulence of the interstellar
medium developed fast in the past decades. The theory of supersonic magnetized
turbulence, as well as the understanding of projection effects of observed
quantities, are still in progress. In this work we explore the characterization
of the turbulent cascade and its damping from observational spectral line
profiles. We address the difference of ion and neutral velocities by clarifying
the nature of the turbulence damping in the partially ionized. We provide
theoretical arguments in favor of the explanation of the larger Doppler
broadening of lines arising from neutral species compared to ions as arising
from the turbulence damping of ions at larger scales. Also, we compute a number
of MHD numerical simulations for different turbulent regimes and explicit
turbulent damping, and compare both the 3-dimensional distributions of velocity
and the synthetic line profile distributions. From the numerical simulations,
we place constraints on the precision with which one can measure the 3D
dispersion depending on the turbulence sonic Mach number. We show that no
universal correspondence between the 3D velocity dispersions measured in the
turbulent volume and minima of the 2D velocity dispersions available through
observations exist. For instance, for subsonic turbulence the correspondence is
poor at scales much smaller than the turbulence injection scale, while for
supersonic turbulence the correspondence is poor for the scales comparable with
the injection scale. We provide a physical explanation of the existence of such
a 2D-3D correspondence and discuss the uncertainties in evaluating the damping
scale of ions that can be obtained from observations. However, we show that the
statistics of velocity dispersion from observed line profiles can provide the
spectral index and the energy transfer rate of turbulence. Also, comparing two
similar simulations with different viscous coefficients it was possible to
constrain the turbulent cut-off scale. This may especially prove useful since
it is believed that ambipolar diffusion may be one of the dominant dissipative
mechanism in star-forming regions. In this case, the determination of the
ambipolar diffusion scale may be used as a complementary method for the
determination of magnetic field intensity in collapsing cores. We discuss the
implications of our findings in terms of a new approach to magnetic field
measurement proposed by Li & Houde (2008).",1003.2346v1
2011-09-07,Weakly collisional Landau damping and three-dimensional Bernstein-Greene-Kruskal modes: New results on old problems,"Landau damping and Bernstein-Greene-Kruskal (BGK) modes are among the most
fundamental concepts in plasma physics. While the former describes the
surprising damping of linear plasma waves in a collisionless plasma, the latter
describes exact undamped nonlinear solutions of the Vlasov equation. There does
exist a relationship between the two: Landau damping can be described as the
phase-mixing of undamped eigenmodes, the so-called Case-Van Kampen modes, which
can be viewed as BGK modes in the linear limit. While these concepts have been
around for a long time, unexpected new results are still being discovered. For
Landau damping, we show that the textbook picture of phase-mixing is altered
profoundly in the presence of collision. In particular, the continuous spectrum
of Case-Van Kampen modes is eliminated and replaced by a discrete spectrum,
even in the limit of zero collision. Furthermore, we show that these discrete
eigenmodes form a complete set of solutions. Landau-damped solutions are then
recovered as true eigenmodes (which they are not in the collisionless theory).
For BGK modes, our interest is motivated by recent discoveries of electrostatic
solitary waves in magnetospheric plasmas. While one-dimensional BGK theory is
quite mature, there appear to be no exact three-dimensional solutions in the
literature (except for the limiting case when the magnetic field is
sufficiently strong so that one can apply the guiding-center approximation). We
show, in fact, that two- and three-dimensional solutions that depend only on
energy do not exist. However, if solutions depend on both energy and angular
momentum, we can construct exact three-dimensional solutions for the
unmagnetized case, and two-dimensional solutions for the case with a finite
magnetic field. The latter are shown to be exact, fully electromagnetic
solutions of the steady-state Vlasov-Poisson-Amp\`ere system.",1109.1353v1
2012-11-06,Torsional Alfvén waves in solar partially ionized plasma: effects of neutral helium and stratification,"Ion-neutral collisions may lead to the damping of Alfven waves in
chromospheric and prominence plasmas. Neutral helium atoms enhance the damping
in certain temperature interval, where the ratio of neutral helium and neutral
hydrogen atoms is increased. Therefore, the height-dependence of ionization
degrees of hydrogen and helium may influence the damping rate of Alfven waves.
We aim to study the effect of neutral helium in the damping of Alfven waves in
stratified partially ionized plasma of the solar chromosphere. We consider a
magnetic flux tube, which is expanded up to 1000 km height and then becomes
vertical due to merging with neighboring tubes, and study the dynamics of
linear torsional Alfven waves in the presence of neutral hydrogen and neutral
helium atoms. We start with three-fluid description of plasma and consequently
derive single-fluid magnetohydrodynamic (MHD) equations for torsional Alfven
waves. Thin flux tube approximation allows to obtain the dispersion relation of
the waves in the lower part of tubes, while the spatial dependence of
steady-state Alfven waves is governed by Bessel type equation in the upper part
of tubes. Consecutive derivation of single-fluid MHD equations results in a new
Cowling diffusion coefficient in the presence of neutral helium which is
different from previously used one. We found that shorter-period (< 5 s)
torsional Alfven waves damp quickly in the chromospheric network due to
ion-neutral collision. On the other hand, longer-period (> 5 s) waves do not
reach the transition region as they become evanescent at lower heights in the
network cores. Propagation of torsional Alfven waves through the chromosphere
into the solar corona should be considered with caution: low-frequency waves
are evanescent due to the stratification, while high-frequency waves are damped
due to ion neutral collisions.",1211.1348v2
2013-05-16,Application of vibration-transit theory to distinct dynamic response for a monatomic liquid,"We examine the distinct part of the density autocorrelation function Fd(q,t),
also called the intermediate scattering function, from the point of view of the
vibration-transit (V-T) theory of monatomic liquid dynamics. A similar study
has been reported for the self part, and we study the self and distinct parts
separately because their damping processes are not simply related. We begin
with the perfect vibrational system, which provides precise definitions of the
liquid correlations, and provides the vibrational approximation Fdvib(q,t) at
all q and t. Two independent liquid correlations are defined, motional and
structural, and these are decorrelated sequentially, with a crossover time
tc(q). This is done by two independent decorrelation processes: the first,
vibrational dephasing, is naturally present in Fdvib(q,t) and operates to damp
the motional correlation; the second, transit-induced decorrelation, is invoked
to enhance the damping of motional correlation, and then to damp the structural
correlation. A microscopic model is made for the ""transit drift"", the averaged
transit motion that damps motional correlation on 0 < t < tc(q). Following the
previously developed self-decorrelation theory, a microscopic model is also
made for the ""transit random walk,"" which damps the structural correlation on t
> tc(q). The complete model incorporates a property common to both self and
distinct decorrelation: simple exponential decay following a delay period,
where the delay is tc(q, the time required for the random walk to emerge from
the drift. Our final result is an accurate expression for Fd(q,t) for all q
through the first peak in Sd(q). The theory is calibrated and tested using
molecular dynamics (MD) calculations for liquid Na at 395K; however, the theory
itself does not depend on MD, and we consider other means for calibrating it.",1305.3954v2
2015-04-01,Landau damping of Gardner solitons in a dusty bi-ion plasma,"The effects of linear Landau damping on the nonlinear propagation of
dust-acoustic solitary waves (DASWs) are studied in a collisionless
unmagnetized dusty plasma with two species of positive ions. The extremely
massive, micron-seized, cold and negatively charged dust particles are
described by fluid equations, whereas the two species of positive ions, namely
the cold (heavy) and hot (light) ions are described by the kinetic Vlasov
equations. Following Ott and Sudan [Phys. Fluids {\bf 12}, 2388 (1969)], and by
considering lower and higher-order perturbations, the evolution of DASWs with
Landau damping is shown to be governed by Korteweg-de Vries (KdV), modified KdV
(mKdV) or Gardner (KdV-mKdV)-like equations. The properties of the phase
velocity and the Landau damping rate of DASWs are studied for different values
of the ratios of the temperatures $(\sigma)$ and the number densities $(\mu)$
of hot and cold ions as well the cold to hot ion mass ratio $m$. The
distinctive features of the decay rates of the amplitudes of the KdV, mKdV and
Gardner solitons with a small effect of Landau damping are also studied in
different parameter regimes. It is found that the Gardner soliton points to
lower wave amplitudes than the KdV and mKdV solitons. The results may be useful
for understanding the localization of solitary pulses and associated wave
damping (collisionless) in laboratory and space plasmas (e.g., the F-ring of
Saturn) in which the number density of free electrons is much smaller than that
of ions and the heavy, micron seized dust grains are highly charged.",1504.00089v2
2017-03-09,Material developments and domain wall based nanosecond-scale switching process in perpendicularly magnetized STT-MRAM cells,"We investigate the Gilbert damping and the magnetization switching of
perpendicularly magnetized FeCoB-based free layers embedded in tunnel junctions
adequate for spin-torque operated memories. We study the influence of the boron
content in MgO / FeCoB /Ta systems alloys on their Gilbert damping after
crystallization annealing. Increasing the boron content from 20 to 30\%
increases the crystallization temperature, thereby postponing the onset of
elemental diffusion within the free layer. This reduction of the interdiffusion
of the Ta atoms helps maintaining the Gilbert damping at a low level of 0.009
without any penalty on the anisotropy and the magneto-transport properties up
to the 400$^\circ$C annealing required in CMOS back-end of line processing. In
addition, we show that dual MgO free layers of composition
MgO/FeCoB/Ta/FeCoB/MgO have a substantially lower damping than their
MgO/FeCoB/Ta counterparts, reaching damping parameters as low as 0.0039 for a 3
\r{A} thick Tantalum spacer. This confirms that the dominant channel of damping
is the presence of Ta impurities within the FeCoB alloy. On optimized tunnel
junctions, we then study the duration of the switching events induced by
spin-transfer-torque. We focus on the sub-threshold thermally activated
switching in optimal applied field conditions. From the electrical signatures
of the switching, we infer that once the nucleation has occurred, the reversal
proceeds by a domain wall sweeping though the device at a few 10 m/s. The
smaller the device, the faster its switching. We present an analytical model to
account for our findings. The domain wall velocity is predicted to scale
linearly with the current for devices much larger than the wall width. The wall
velocity depends on the Bloch domain wall width, such that the devices with the
lowest exchange stiffness will be the ones that host the domain walls with the
slowest mobilities.",1703.03198v3
2013-09-16,Two-atom system as a nano-antenna for mode switching and light routing,"We determine how a system composed of two nonidentical two-level atoms with
different resonance frequencies and different damping rates could work as a
nano-antenna for controlled mode switching and light routing. We calculate the
angular distribution of the emitted field detected in a far-field zone of the
system including the direct interatomic interactions and arbitrary linear
dimensions of the system. The calculation is carried out in terms of the
symmetric and antisymmetric modes of the two atom system. We find that as long
as the atoms are identical, the emission cannot be switched between the
symmetric and antisymmetric modes. The switching may occur when the atoms are
non-identical and the emission can then be routed to different modes by
changing the relative ratio of the atomic frequencies, or damping rates or by a
proper tuning of the laser frequency to the atomic resonance frequencies. It is
shown that in the case of atoms of different resonance frequencies but equal
damping rates, the light routing is independent of the frequency of the driving
laser field. It depends only on the sign of the detuning between the atomic
resonance frequencies. In the case of atoms of different damping rates, the
emission can be switched between different modes by changing the laser
frequency from the blue to red detuned from the atomic resonance. The effect of
the interatomic interactions is also considered and it is found that in the
case of unequal resonance frequencies of the atoms, the interactions slightly
modify the visibility of the intensity pattern. The case of unequal damping
rates of the atoms is affected rather more drastically, the light routing
becoming asymmetric under the dipole-dipole interaction with the enhanced
intensities of the modes turned towards the atom of smaller damping rate.",1309.3924v1
2017-07-18,Explanations of the DAMPE high energy electron/positron spectrum in the dark matter annihilation and pulsar scenarios,"Many studies have shown that either the nearby astrophysical source or dark
matter (DM) annihilation/decay is required to explain the origin of high energy
cosmic ray (CR) $e^\pm$, which are measured by many experiments, such as PAMELA
and AMS-02. Recently, the Dark Matter Particle Explorer (DAMPE) collaboration
has reported its first result of the total CR $e^\pm$ spectrum from $25
\,\mathrm{GeV}$ to $4.6 \,\mathrm{TeV}$ with high precision. In this work, we
study the DM annihilation and pulsar interpretations of the DAMPE high energy
$e^\pm$ spectrum. In the DM scenario, the leptonic annihilation channels to
$\tau^+\tau^-$, $4\mu$, $4\tau$, and mixed charged lepton final states can well
fit the DAMPE result, while the $\mu^+\mu^-$ channel has been excluded. In
addition, we find that the mixed charged leptons channel would lead to a sharp
drop at $\sim$ $\mathrm{TeV}$. However, these DM explanations are almost
excluded by the observations of gamma-ray and CMB, unless some complicated DM
models are introduced. In the pulsar scenario, we analyze 21 nearby known
pulsars and assume that one of them is the primary source of high energy CR
$e^\pm$.Considering the constraint from the Fermi-LAT observation of the
$e^\pm$ anisotropy, we find that two pulsars are possible to explain the DAMPE
data. Our results show that it is difficult to distinguish between the DM
annihilation and single pulsar explanations of high energy $e^\pm$ with the
current DAMPE result.",1707.05664v2
2018-10-30,Effect of Landau damping on ion acoustic solitary waves in a multi-species collisionless unmagnetized plasma consisting of nonthermal and isothermal electrons,"A Korteweg-de Vries (KdV) equation including the effect of Landau damping is
derived to study the propagation of weakly nonlinear and weakly dispersive ion
acoustic waves in a collisionless unmagnetized plasma consisting of warm
adiabatic ions and two different species of electrons at different
temperatures. The hotter energetic electron species follows the nonthermal
velocity distribution of Cairns et al. [Geophys. Res. Lett. 22, 2709 (1995)]
whereas the cooler electron species obeys the Boltzmann distribution. It is
found that the coefficient of the nonlinear term of this KdV like evolution
equation vanishes along different family of curves in different parameter
planes. In this context, a modified KdV (MKdV) equation including the effect of
Landau damping effectively describes the nonlinear behaviour of ion acoustic
waves. It has also been observed that the coefficients of the nonlinear terms
of the KdV and MKdV like evolution equations including the effect of Landau
damping, are simultaneously equal to zero along a family of curves in the
parameter plane. In this situation, we have derived a further modified KdV
(FMKdV) equation including the effect of Landau damping to describe the
nonlinear behaviour of ion acoustic waves. In fact, different modified KdV like
evolution equations including the effect of Landau damping have been derived to
describe the nonlinear behaviour of ion acoustic waves in different region of
parameter space. The method of Ott & Sudan [Phys. Fluids 12, 2388 (1969)] has
been applied to obtain the solitary wave solution of the evolution equation
having the nonlinear term $(\phi^{(1)})^{r}\frac{\partial \phi^{(1)}}{\partial
\xi}$, where $\phi^{(1)}$ is the first order perturbed electrostatic potential
and $r =1,2,3$. We have found that the amplitude of the solitary wave solution
decreases with time for all $r =1,2,3$.",1810.12739v1
2019-06-12,Study of Alfven Eigenmodes stability in plasma with multiple NBI driven energetic particle specie,"The aim of this study is to analyze the destabilization of Alfven Eigenmodes
(AE) by multiple energetic particles (EP) species in DIII-D and LHD discharges.
We use the reduced MHD equations to describe the linear evolution of the
poloidal flux and the toroidal component of the vorticity in a full 3D system,
coupled with equations of density and parallel velocity moments for the
energetic particles species, including the effect of the acoustic modes,
diamagnetic currents and helical couplings. We add the Landau damping and
resonant destabilization effects using a closure relation. The simulations with
multiple NBI lines show three different regimes: the non damped regime where
the multi beam AEs growth rate is larger compared to the growth rate of the AEs
destabilized by the individual NBI lines, the interaction regime where the
multi beam AEs growth rate is smaller than the single NBI AEs and the damped
regime where the AEs are suppressed. Operations in the damped regime requires
EP species with different density profile flatness or gradient locations. In
addition, the AEs growth rate in the interaction regime is further reduced if
the combined NBI lines have similar beam temperatures and the beta of the NBI
line with flatter EP density profile increases. Then, optimization trends are
identified in DIII-D high poloidal beta and LHD low density / magnetic field
discharges with multiple NBI lines as well as the configuration requirements to
operate in the damped and interaction regimes. DIII-D simulations show a
decrease of the n=2 to 6 AEs growth rate and n=1 AE are stabilized in the LHD
case. The helical coupling effects in LHD simulations lead to a transition from
the interaction to the damped regime of the n=2,-8,12 helical family.",1906.05701v1
2018-06-27,In-flight performance of the DAMPE silicon tracker,"DAMPE (DArk Matter Particle Explorer) is a spaceborne high-energy cosmic ray
and gamma-ray detector, successfully launched in December 2015. It is designed
to probe astroparticle physics in the broad energy range from few GeV to 100
TeV. The scientific goals of DAMPE include the identification of possible
signatures of Dark Matter annihilation or decay, the study of the origin and
propagation mechanisms of cosmic-ray particles, and gamma-ray astronomy. DAMPE
consists of four sub-detectors: a plastic scintillator strip detector, a
Silicon-Tungsten tracKer-converter (STK), a BGO calorimeter and a neutron
detector. The STK is composed of six double layers of single-sided silicon
micro-strip detectors interleaved with three layers of tungsten for photon
conversions into electron-positron pairs. The STK is a crucial component of
DAMPE, allowing to determine the direction of incoming photons, to reconstruct
tracks of cosmic rays and to estimate their absolute charge (Z). We present the
in-flight performance of the STK based on two years of in-flight DAMPE data,
which includes the noise behavior, signal response, thermal and mechanical
stability, alignment and position resolution.",1806.10355v1
2018-07-31,"Comparative study of methodologies to compute the intrinsic Gilbert damping: interrelations, validity and physical consequences","Relaxation effects are of primary importance in the description of magnetic
excitations, leading to a myriad of methods addressing the phenomenological
damping parameters. In this work, we consider several well-established forms of
calculating the intrinsic Gilbert damping within a unified theoretical
framework, mapping out their connections and the approximations required to
derive each formula. This scheme enables a direct comparison of the different
methods on the same footing and a consistent evaluation of their range of
validity. Most methods lead to very similar results for the bulk ferromagnets
Fe, Co and Ni, due to the low spin-orbit interaction strength and the absence
of the spin pumping mechanism. The effects of inhomogeneities, temperature and
other sources of finite electronic lifetime are often accounted for by an
empirical broadening of the electronic energy levels. We show that the
contribution to the damping introduced by this broadening is additive, and so
can be extracted by comparing the results of the calculations performed with
and without spin-orbit interaction. Starting from simulated ferromagnetic
resonance spectra based on the underlying electronic structure, we
unambiguously demonstrate that the damping parameter obtained within the
constant broadening approximation diverges for three-dimensional bulk magnets
in the clean limit, while it remains finite for monolayers. Our work puts into
perspective the several methods available to describe and compute the Gilbert
damping, building a solid foundation for future investigations of magnetic
relaxation effects in any kind of material.",1807.11808v3
2019-03-28,Improving convergence of volume penalised fluid-solid interactions,"We analyse and improve the volume-penalty method, a simple and versatile way
to model objects in fluid flows. The volume-penalty method is a kind of
fictitious-domain method that approximates no-slip boundary conditions with
rapid linear damping inside the object. The method can then simulate complex,
moving objects in general numerical solvers without specialised algorithms or
boundary-conforming grids. Volume penalisation pays for this simplicity by
introducing an equation-level error, the $\textit{model error}$, that is
related to the damping time $\eta \ll 1$. While the model error has been proven
to vanish as the damping time tends to zero, previous work suggests convergence
at a slow rate of $\mathcal{O}(\eta^{1/2})$. The stiffness of the damping
implies conventional volume penalisation only achieves first order numerical
accuracy. We analyse the volume-penalty method using multiple-scales
matched-asymptotics with a signed-distance coordinate system valid for
arbitrary smooth geometries. We show the dominant model error stems from a
displacement length that is proportional to a Reynolds number $\text{Re}$
dependent boundary layer of size $\mathcal{O}(\eta^{1/2}\text{Re}^{-1/2})$. The
relative size of the displacement length and damping time leads to multiple
error regimes. Our key finding derives a simple smoothing prescription for the
damping that eliminates the displacement length and reduces the model error to
$\mathcal{O}(\eta)$ in all regimes. This translates to second order numerical
accuracy. We validate our findings in several comprehensive benchmark problems
and finally combine Richardson extrapolation of the model error with our
correction to further improve convergence to $\mathcal{O}(\eta^{2})$.",1903.11914v4
2019-11-05,Observation of Nanoscale Opto-Mechanical Molecular Damping; Origin of Spectroscopic Contrast in Photo Induced Force Microscopy,"We experimentally investigated the contrast mechanism of infrared
photoinduced force microscopy (PiFM) for recording vibrational resonances.
Extensive experiments have demonstrated that spectroscopic contrast in PiFM is
mediated by opto-mechanical damping of the cantilever oscillation as the
optical wavelength is scanned through optical resonance. To our knowledge, this
is the first time opto-mechanical damping has been observed in the AFM. We
hypothesize that this damping force is a consequence of the dissipative
interaction between the sample and the vibrating tip; the modulated light
source in PiFM modulates the effective damping constant of the 2nd eigenmode of
the cantilever which in turn generate side-band signals producing the PiFM
signal at the 1st eigenmode. A series of experiments have eliminated other
mechanisms of contrast. By tracking the frequency shift of the PiFM signal at
the 1st cantilever eigenmode as the excitation wavenumber is tuned through a
mid-infrared absorption band, we showed that the near-field optical interaction
is attractive. By using a vibrating piezoelectric crystal to mimic sample
thermal expansion in a PiFM operating in mixing mode, we determined that the
minimum thermal expansion our system can detect is 30 pm limited by system
noise. We have confirmed that van der Waal mediated thermal-expansion forces
have negligible effect on PiFM signals by detecting the resonant response of a
4-methylbenzenethiol mono molecular layer deposited on template-stripped gold,
where thermal expansion was expected to be < 3 pm, i.e., 10 times lower than
our system noise level. Finally, the basic theory for dissipative tip-sample
interactions was introduced to model the photoinduced opto-mechanical damping.
Theoretical simulations are in excellent agreement with experiment.",1911.05190v1
2020-06-08,Stochastic re-acceleration and magnetic-field damping in Tycho's supernova remnant,"A number of studies suggest that shock acceleration with particle feedback
and very efficient magnetic-field amplification combined with Alfv\'{e}nic
drift are needed to explain the rather soft radio spectrum and the narrow rims
observed for Tycho's SNR. We show that the broadband spectrum of Tycho's SNR
can alternatively be well explained when accounting for stochastic acceleration
as a secondary process. The re-acceleration of particles in the turbulent
region immediately downstream of the shock should be efficient enough to impact
particle spectra over several decades in energy. The so-called Alfv\'{e}nic
drift and particle feedback on the shock structure are not required in this
scenario. Additionally, we investigate whether synchrotron losses or
magnetic-field damping play a more profound role in the formation of the
non-thermal filaments. We solve the full particle transport equation in
test-particle mode using hydrodynamic simulations of the SNR plasma flow. The
background magnetic field is either computed from the induction equation or
follows analytic profiles, depending on the model considered. Fast-mode waves
in the downstream region provide the diffusion of particles in momentum space.
We show that the broadband spectrum of Tycho can be well explained if
magnetic-field damping and stochastic re-acceleration of particles are taken
into account. Although not as efficient as standard DSA, stochastic
acceleration leaves its imprint on the particle spectra, which is especially
notable in the emission at radio wavelengths. We find a lower limit for the
post-shock magnetic-field strength $\sim330\,\mathrm{\mu G}$, implying
efficient amplification even for the magnetic-field damping scenario. For the
formation of the filaments in the radio range magnetic-field damping is
necessary, while the X-ray filaments are shaped by both the synchrotron losses
and magnetic-field damping.",2006.04832v1
2021-02-23,Influence of Ion-Neutral Damping on the Cosmic-Ray Streaming Instability: Magnetohydrodynamic Particle-in-cell Simulations,"We explore the physics of the gyro-resonant cosmic ray streaming instability
(CRSI) including the effects of ion-neutral (IN) damping. This is the main
damping mechanism in (partially-ionized) atomic and molecular gas, which are
the primary components of the interstellar medium (ISM) by mass. Limitation of
CRSI by IN damping is important in setting the amplitude of Alfv\'en waves that
scatter cosmic rays and control galactic-scale transport. Our study employs the
MHD-PIC hybrid fluid-kinetic numerical technique to follow linear growth as
well as post-linear and saturation phases. During the linear phase of the
instability -- where simulations and analytical theory are in good agreement --
IN damping prevents wave growth at small and large wavelengths, with the
unstable bandwidth lower for higher ion-neutral collision rate $\nu_{\rm in}$.
Purely MHD effects during the post-linear phase extend the wave spectrum
towards larger $k$. In the saturated state, the cosmic ray distribution evolves
toward greater isotropy (lower streaming velocity) by scattering off of Alv\'en
waves excited by the instability. In the absence of low-$k$ waves, CRs with
sufficiently high momentum are not isotropized. The maximum wave amplitude and
rate of isotropization of the distribution function decreases at higher
$\nu_{\rm in}$. When the IN damping rate approaches the maximum growth rate of
CSRI, wave growth and isotropization is suppressed. Implications of our results
for CR transport in partially ionized ISM phases are discussed.",2102.11878v3
2022-06-17,Quantum Dynamics of Magnetic Skyrmions: Consistent Path Integral Formulation,"We present a path integral formalism for the intrinsic quantum dynamics of
magnetic skyrmions coupled to a thermal background of magnetic fluctuations.
Upon promoting the skyrmion's collective coordinate $\boldsymbol{R}$ to a
dynamic variable and integrating out the magnonic heat bath, we derive the
generalized equation of motion for $\boldsymbol{R}$ with a non-local damping
term that describes a steady-state skyrmion dynamics at finite temperatures.
Being essentially temperature dependent, the intrinsic damping is shown to
originate from the coupling of thermally activated magnon modes to the
adiabatic potential driven by a rigid skyrmion motion, which can be regarded as
another manifestation of emergent electrodynamics inherent to topological
magnetic textures. We further argue that the diagonal components of the damping
term act as the source of dissipation and inertia, while its off-diagonal
components modify the gyrotropic motion of a magnetic skyrmion. By means of
numerical calculations for the lattice spin model of chiral ferromagnets, we
study the temperature behavior of the intrinsic damping as a function of
magnetic field in periodic and confined geometries. The intrinsic damping is
demonstrated to be highly non-local, revealing its quantum-mechanical nature,
that becomes more pronounced with increasing temperature. At high temperatures
when the magnon occupation factors are large, the intrinsic damping is shown to
yield a modified Thiele's equation with the additional non-local dissipative
and mass terms that exhibit an almost linear temperature behavior. Our results
provide a microscopic background for semiclassical magnetization dynamics and
establish a framework for understanding spin caloritronics effects in
topological magnetic textures.",2206.08532v2
2024-02-05,Revisiting the role of cosmic-ray driven Alfvén waves in pre-existing magnetohydrodynamic turbulence. I. Turbulent damping rates and feedback on background fluctuations,"Alfv\'en waves (AWs) excited by the cosmic-ray (CR) streaming instability
(CRSI) are a fundamental ingredient for CR confinement. The effectiveness of
self-confinement relies on a balance between CRSI growth rate and damping
mechanisms acting on quasi-parallel AWs excited by CRs. One relevant mechanism
is the so-called turbulent damping, in which an AW packet injected in
pre-existing turbulence undergoes a cascade process due to its nonlinear
interaction with fluctuations of the background. The turbulent damping of an AW
packet in pre-existing magnetohydrodynamic turbulence is re-examined, revised,
and extended to include most-recent theories of MHD turbulence that account for
dynamic alignment and reconnection-mediated regime. The case in which the role
of feedback of CR-driven AWs on pre-existing turbulence is important will also
be discussed. Particular attention is given to the nonlinearity parameter
$\chi^w$ that estimates the strength of nonlinear interaction between CR-driven
AWs and background fluctuations. We point out the difference between $\chi^w$
and $\chi^z$ that instead describes the strength of nonlinear interactions
between pre-existing fluctuations. When $\chi^w$ is properly taken into
account, one finds that (i) the turbulent damping rate of quasi-parallel AWs in
anisotropic turbulence depends on the background-fluctuations' amplitude to the
third power, hence is strongly suppressed, and (ii) the dependence on the AW's
wavelength (and thus on the CR gyro-radius from which it is excited) is
different from what has been previously obtained. Finally, (iii) when dynamic
alignment of cascading fluctuations and the possibility of a
reconnection-mediated range is included in the picture, the turbulent damping
rate exhibits novel regimes and breaks. Finally, a criterion for CR-feedback is
derived and simple phenomenological models of CR-modified turbulent scaling are
provided.",2402.02901v1
2006-10-24,Logical contradictions of Landau damping,"Landau damping/growing at boundary condition of excitation of a harmonic wave
in collisionless ion-electron-neutrals plasma contradicts to the law of energy
conservation of a wave damping/growing in space. There is also no criterion of
a choice either damping or growing solution in difference from always
non-damping in the direction of propagation Vlasov waves. Variety of other
incongruities as consequence of Landau damping is specified also. Absence of
explicit positivity and finiteness of wave solutions for electron distribution
function near singularity point leads to need of imposing additional cutting
off constraints with resulting positivity and finiteness of the electron
distribution function at the singularity points and finiteness of the complex
dispersion integral. Landau damping as a real physical phenomenon of
collisionless damping does not exist. A relation is established for the real
dispersion equation with real waves (see Appendices 2,4) between the averaged
over period wave damping decrement and the collisional energy-exchange term of
kinetic equation. Collisionless Vlasov-Landau damping is explained finally by
the usual wrong use of nonlinearly complex wave functions leading to complex
dispersion equation. All used solution of the complex dispersion equation for
the simultaneously existing collisionless both exponentially damping and
growing nonlinear complex waves is entirely, quantitatively and in its logical
sense, different from the solution of initially real dispersion equation for
real either damping or growing waves and should be discarded (see Appendices
2,4,5,6). Collisionless damping is caused by unreasonable use of wave functions
with complex frequency or complex wave number leading to complex dispersion
relation with unphysical binomial virtual complex roots. Thus finding roots of
the complex dispersion equation has only abstract mathematical interest.",0610220v67
1997-07-11,Limits from rapid TeV variability of Mrk 421,"The extreme variability event in the TeV emission of Mrk 421, recently
reported by the Whipple team, imposes the tightest limits on the typical size
of the TeV emitting regions in Active Galactic Nuclei (AGN). We examine the
consequences that this imposes on the bulk Lorentz factor of the emitting
plasma and on the radiation fields present in the central region of this Active
Nucleus. No strong evidence is found for extreme Lorentz factors. However,
energetics arguments suggest that any accretion in Mrk 421 has to take place at
small rates, compatible with an advection-dominated regime.",9707131v1
1998-06-12,Energy spectra of cosmic rays accelerated at ultrarelativistic shock waves,"Energy spectra of particles accelerated by the first-order Fermi mechanism
are investigated at ultrarelativistic shock waves, outside the range of Lorentz
factors considered previously. For particle transport near the shock a
numerical method involving small amplitude pitch-angle scattering is applied
for flows with Lorentz factors $\gamma$ from 3 to 243. For large $\gamma$
shocks a convergence of derived energy spectral indices up to the value
$\sigma_\infty \approx 2.2$ is observed for all considered turbulence
amplitudes and magnetic field configurations. Recently the same index was
derived for $\gamma$-ray bursts by Waxman [Astrophys. J. Lett. 485, L5 (1997)].",9806181v1
1999-05-26,Is the Universe transparent to TeV photons?,"If Lorentz invariance is broken at an energy scale Eq, as has recently been
suggested in the context of attempts to quantize gravity, the kinematics of
photon-photon collisions would be profoundly affected at lower energies.
Specifically, electron-positron pair creation on soft photons may be forbidden
at photon energies as low as 30 TeV times square root of (Eq/10**17 GeV) and
the Universe would then be transparent to high energy photons.
  The proposition that Lorentz invariance is broken may be falsified by the
techniques of TeV astronomy.",9905308v1
1999-11-06,Radio Astronomical Polarimetry and the Lorentz Group,"In radio astronomy the polarimetric properties of radiation are often
modified during propagation and reception. Effects such as Faraday rotation,
receiver cross-talk, and differential amplification act to change the state of
polarized radiation. A general description of such transformations is useful
for the investigation of these effects and for the interpretation and
calibration of polarimetric observations. Such a description is provided by the
Lorentz group, which is intimately related to the transformation properties of
polarized radiation. In this paper the transformations that commonly arise in
radio astronomy are analyzed in the context of this group. This analysis is
then used to construct a model for the propagation and reception of radio
waves. The implications of this model for radio astronomical polarimetry are
discussed.",9911101v1
2000-09-05,A vorton gun,"In about half of all near-cusp events in superconducting cosmic strings with
chiral currents (and probably with general currents as well), the string
intersects itself near the cusp. Intercommutation causes the conversion of the
string near the cusp into a vorton (in the chiral case) with very high Lorentz
boost. We demonstrate how to analyze the cusp shape in a Lorentz frame that
makes the motion simple, by the use of a 5-dimensional procedure, and analyze
the resulting production of vortons.",0009072v1
2001-02-13,New Tests of Lorentz Invariance Following from Observations of the Highest Energy Cosmic Gamma Rays,"We use the recent reanalysis of multi-TeV gamma-ray observations of Mrk 501
to constrain the Lorentz invariance breaking parameter involving the maximum
electron velocity. Our limit is two orders of magnitude better than that
obtained from the maximum observed cosmic-ray electron energy.",0102226v2
2002-01-04,Quantum-gravity phenomenology with gamma rays and UHE cosmic rays,"In recent years several ideas for experimental searches of effects induced by
quantum properties of space-time have been discussed. Some of these ideas
concern the role in quantum spacetime of the ordinary Lorentz symmetry of
classical flat spacetime. Deviations from ordinary (classical) Lorentz symmetry
are now believed to be rather natural in non-commutative space-times, models
based on String Theory and models based on Loop Quantum Gravity. Observations
of gamma rays and ultra-high-energy cosmic rays could play a key role in the
development of this research programme.",0201047v1
2003-01-19,Evolution of an afterglow with a hard electron spectrum,"Diffusive shock acceleration theory suggests that the ``universal'' energy
spectrum of electrons with a power-law index p approximately equal to 2.3,
commonly used to model GRB afterglows, cannot extend below an electron lorentz
factor gamma_e equal to the bulk lorentz factor of the blast wave multiplied by
the ratio of proton and electron masses. We suggest that the electron energy
distribution has a slope p < 2 below this limit, down to an appropriate
gamma_m. A two-slope spectrum such as this provides a good model for the
afterglow of GRB010222.",0301379v1
2003-01-29,Light Propagation in the Gravitational Field of Moving Bodies by means of Lorentz Transformation. I. Mass monopoles moving with constant velocities,"We show how to derive the equations of light propagation in the gravitational
field of uniformly moving mass monopoles without formulating and integrating
the differential equations of light propagation in that field. The well-known
equations of light propagation in the gravitational field of a motionless mass
monopole are combined with a suitable Lorentz transformation. The possibility
to generalize this technique for the more complicated case of uniformly moving
body of arbitrary multipole structure is discussed.",0301573v2
2003-10-14,"Cosmological acceleration, varying couplings, and Lorentz breaking","Many candidate fundamental theories contain scalar fields that can acquire
spacetime-varying expectation values in a cosmological context. Such scalars
typically obey Lorentz-violating effective dispersion relations. We illustrate
this fact within a simple supergravity model that also exhibits the observed
late-time cosmological acceleration and implies varying electromagnetic
couplings.",0310344v1
2005-06-23,A short note on climbing gravity improbable: Superradiant ring fellowship of launching the high Lorentz-factor outflows/jets,"The spin energy extraction from a rotating black hole by amplification of
scalar waves inside superradiance resonance wedge cavity (ring), followed by
jet formation via magnetic reconnection assisted by the amplified scalar
fields, is proposed. This mechanism may explain the availability of energy for
as well as the formation of relativistic jets with high Lorentz-factor in
microquasars and quasars. It is speculated that it may also explain that the
spin of the central black hole, which facilitates the formation of
superradiance cavity, which in turn would produce the amplified scalar waves by
taking the hole's spin energy, is the source for the distinction between
radio-loud and radio-quiet active galaxies.",0506557v1
2006-10-04,The Cosmology of a Universe with Spontaneously-Broken Lorentz Symmetry,"A self consistent effective field theory of modified gravity has recently
been proposed with spontaneous breaking of local Lorentz invariance. The
symmetry is broken by a vector field with the wrong-sign mass term and it has
been shown to have additional graviton modes and modified dispersion relations.
In this paper we study the evolution of a homogeneous and isotropic universe in
the presence of such a vector field with a minimum lying along the time-like
direction. A plethora of different regimes is identified, such as accelerated
expansion, loitering, collapse and tracking.",0610125v1
1995-01-02,Lyapunov exponents and anomalous diffusion of a Lorentz gas with infinite horizon using approximate zeta functions,"We compute the Lyapunov exponent, generalized Lyapunov exponents and the
diffusion constant for a Lorentz gas on a square lattice, thus having infinite
horizon. Approximate zeta functions, written in terms of probabilities rather
than periodic orbits, a re used in order to avoid the convergence problems of
cycle expansions. The emphasis is on the relation between the analytic
structure of the zeta function, where a branch cut plays an important role, and
the asymptotic dynamics of the system. We find a diverging diffusion constant
$D(t) \sim \log t$ and a phase transition for the generalized Lyapunov
exponents.",9501001v1
1997-05-12,Chaos properties and localization in Lorentz lattice gases,"The thermodynamic formalism of Ruelle, Sinai, and Bowen, in which chaotic
properties of dynamical systems are expressed in terms of a free energy-type
function - called the topological pressure - is applied to a Lorentz Lattice
Gas, as typical for diffusive systems with static disorder. In the limit of
large system sizes, the mechanism and effects of localization on large clusters
of scatterers in the calculation of the topological pressure are elucidated and
supported by strong numerical evidence. Moreover it clarifies and illustrates a
previous theoretical analysis [Appert et al. J. Stat. Phys. 87,
chao-dyn/9607019] of this localization phenomenon.",9705011v1
1995-12-02,The Magnus Force on Skyrmions in Ferromagnets and the Quantum Hall Effect,"The topological solitons, or ``skyrmions'', in a planar ferromagnet
experience a Magnus force proportional to the product of their velocity and the
surrounding magnetization. It has been suggested that the charged
quasiparticles near filling factor $\nu=1$ in the $GaAs$ quantum Hall effect
are skyrmions. If so we might expect this spin-induced Magnus force to act on
the quasiparticles in addition to the Lorentz force they experience because of
their charge. We show that this is not the case, and that the Magnus and
Lorentz forces are merely different descriptions of the same physical effect.",9512010v1
1997-01-14,Lorentz-Lorenz shift in a Bose-Einstein condensate,"We study the quantum field theory of light-matter interactions for quantum
degenerate atomic gases at low light intensity. We argue that the contact
interactions between atoms emerging in the dipole gauge may be ignored.
Specifically, they are canceled by concurrent infinite level shifts of the
atoms. Our development yields the classic Lorentz-Lorenz local-field shift of
the atomic resonance.",9701088v2
1997-03-07,"From Lorentz Force on Electron to Magnus Force on Vortex, Role of Experiments","The vortex motion in a superfluid or a type II superconductor is similar to
the electron motion in a magnetic field, because they both feel a transverse
force. The vortex dynamics in a superconductor is a basic property of the
superconductivity which remains controversial. It is also responsible for a
large class of observed physical phenomena. We will examine this issue from the
experimental point of view. In particular, we will compare the experiments
which have set the stage to the Lorentz force and the experiments influencing
our understanding of the Magnus force on vortices in superconductors.",9703072v1
1997-10-27,Magneto-Transport in the Two-Dimensional Lorentz Gas,"We consider the two-dimensional Lorentz gas with Poisson distributed hard
disk scatterers and a constant magnetic field perpendicular to the plane of
motion. The velocity autocorrelation is computed numerically over the full
range of densities and magnetic fields with particular attention to the
percolation threshold between hopping transport and pure edge currents. The
Ohmic and Hall conductance are compared with mode-coupling theory and a recent
generalized kinetic equation valid for low densities and small fields. We argue
that the long time tail as $t^{-2}$ persists for non-zero magnetic field.",9710282v1
1998-07-15,Applications of Temperley-Lieb algebras to Lorentz lattice gases,"Motived by the study of motion in a random environment we introduce and
investigate a variant of the Temperley-Lieb algebra. This algebra is very rich,
providing us three classes of solutions of the Yang-Baxter equation. This
allows us to establish a theoretical framework to study the diffusive behaviour
of a Lorentz Lattice gas. Exact results for the geometrical scaling behaviour
of closed paths are also presented.",9807221v1
2000-02-06,One-Dimensional Stochastic Lévy-Lorentz Gas,"We introduce a L\'evy-Lorentz gas in which a light particle is scattered by
static point scatterers arranged on a line. We investigate the case where the
intervals between scatterers $\{\xi_i \}$ are independent random variables
identically distributed according to the probability density function $\mu(\xi
)\sim \xi^{-(1 + \gamma)}$. We show that under certain conditions the mean
square displacement of the particle obeys $<x^2 (t) > \ge C t^{3 - \gamma}$ for
$1 < \gamma < 2$. This behavior is compatible with a renewal L\'evy walk
scheme. We discuss the importance of rare events in the proper characterization
of the diffusion process.",0002084v1
2000-11-01,Effective Lorentz Force due to Small-angle Impurity Scattering: Magnetotransport in High-Tc Superconductors,"We show that a scattering rate which varies with angle around the Fermi
surface has the same effect as a periodic Lorentz force on magnetotransport
coefficients. This effect, together with the marginal Fermi liquid inelastic
scattering rate gives a quantitative explanation of the temperature dependence
and the magnitude of the observed Hall effect and magnetoresistance with just
the measured zero-field resistivity as input.",0011020v2
2001-09-21,Higgs Boson in Superconductors,"Superfluid helium, describable by a two-component order parameter, exhibits
only the Bogolubov mode with energy $\to 0$ at long wavelengths, while a
Lorentz-invariant theory with a two-component order parameter exhibits a finite
energy mode at long wavelengths (the Higgs Boson), besides the above mass-less
mode. The mass-less mode moves to high energies if it couples to
electromagnetic fields (the Anderson-Higgs mechanism). Superconductors, on the
other hand have been theoretically and experimentally shown to exhibit both
modes. This occurs because the excitations in superconductors have an
(approximate) particle-hole symmetry and therefore show a similarity to
Lorentz-invariant theories.",0109409v1
2003-10-28,Elementary Excitations in One-Dimensional Electromechanical Systems; Transport with Back-Reaction,"Using an exactly solvable model, we study low-energy properties of a
one-dimensional spinless electron fluid contained in a quantum-mechanically
moving wire located in a static magnetic field. The phonon and electric current
are coupled via Lorentz force and the eigenmodes are described by two
independent boson fluids. At low energies, the two boson modes are charged
while one of them has excitation gap due to back-reaction of the Lorentz force.
The theory is illustrated by evaluating optical absorption spectra. Our results
are exact and show a non-perturbative regime of electron transport.",0310636v1
2005-04-02,General Electrical Manipulations of Electron Spin,"Traditionally, the interactions related to the 3D spatial angular momentum
have been studied completely, while the ones related to the generators of
Lorentz boost are always ignored. In this paper we show that the generators of
Lorentz boost have a nontrivial physical significance in quantum mechanics, and
try to propose a most general theory about electrical manipulations of electron
spin, where a new treatment and interpretation for the traditional Darwin term
and spin-orbit coupling is given via the concept of electron's induced electric
moment. Some electrostatic fields can even affect the spin quantum states of a
resting electron, and parallel electric and magnetic fields can be
simultaneously applied to fix on the spin orientation of electron.",0504049v1
2005-10-17,Localization Transition of the Three-Dimensional Lorentz Model and Continuum Percolation,"The localization transition and the critical properties of the Lorentz model
in three dimensions are investigated by computer simulations. We give a
coherent and quantitative explanation of the dynamics in terms of continuum
percolation theory, an excellent matching of both the critical density and
exponents is obtained. Upon exploiting a dynamic scaling Ansatz employing two
divergent length scales we find data collapse for the mean-square displacements
and identify the leading-order corrections to scaling. The non-Gaussian
parameter is predicted to diverge at the transition.",0510442v2
2006-03-20,Three-dimensional Lorentz model in a magnetic field : exact and Chapman-Enskog solutions,"We derive the exact solution of the Boltzmann kinetic equation for the
three-dimensional Lorentz model in the presence of a constant and uniform
magnetic field. The velocity distribution of the electrons reduces
exponentially fast to its spherically symmetric component. In the long time
hydrodynamic limit there remains only the diffusion process governed by an
anisotropic diffusion tensor. The systematic way of building the Chapman-Enskog
solutions is described.",0603505v2
2006-05-24,Computation of entropy increase for Lorentz gas and hard disks,"Entropy functionals are computed for non-stationary distributions of
particles of Lorentz gas and hard disks. The distributions consisting of beams
of particles are found to have the largest amount of entropy and entropy
increase. The computations show exponentially monotonic increase during initial
time of rapid approach to equilibrium. The rate of entropy increase is bounded
by sums of positive Lyapounov exponents.",0605610v1
1994-12-20,SU(2) $\times$ U(1) Gauge Gravity,"We propose a Lorentz-covariant Yang-Mills ``spin-gauge'' theory, where the
function valued Pauli matrices play the role of a non-scalar Higgs-field. As
symmetry group we choose $SU(2) \times U(1)$ of the 2-spinors describing
particle/antiparticle states. After symmetry breaking a non-scalar
Lorentz-covariant Higgs-field gravity appears, which can be interpreted within
a classical limit as Einstein's metrical theory of gravity, where we restrict
ourselves in a first step to its linearized version.",9412052v1
1995-07-07,Generators of Internal Lorentz Transformations and of General Affine Coordinate Transformations in Teleparallel Theory of (2+1)-Dimensional Gravity --- Cases with Static Circularly Symmetric Space-Times---,"In a teleparallel theory of (2+1)-dimensional gravity developed in a previous
paper, we examine generators of internal Lorentz transformations and of general
affine coordinate transformations for static circularly symmetric exact
solutions of gravitational field equation. The \lq \lq spin"" angular momentum,
the energy-momentum and the \lq \lq extended orbital angular momentum"" are
explicitly given for each solution. Also, we give a critical comment on Deser's
claim that neither momentum nor boosts are definable for finite energy
solutions of three-dimensional Einstein gravity.",9507017v1
1996-08-10,A Covariant Approach To Ashtekar's Canonical Gravity,"A Lorentz and general co-ordinate co-variant form of canonical gravity, using
Ashtekar's variables, is investigated. A co-variant treatment due to Crnkovic
and Witten is used, in which a point in phase space represents a solution of
the equations of motion and a symplectic functional two form is constructed
which is Lorentz and general co-ordinate invariant. The subtleties and
difficulties due to the complex nature of Ashtekar's variables are addressed
and resolved.",9608026v1
1999-10-14,Disclination in Lorentz Space-Time,"The disclination in Lorentz space-time is studied in detail by means of
topological properties of $\phi $-mapping. It is found the space-time
disclination can be described in term of a Dirac spinor. The size of the
disclination, which is proved to be the difference of two sets of su(2)% -like
monopoles expressed by two mixed spinors, is quantized topologically in terms
of topological invariants$-$winding number. The projection of space-time
disclination density along an antisymmetric tensor field is characterized by
Brouwer degree and Hopf index.",9910051v2
2000-02-22,Locating Boosted Kerr and Schwarzschild Apparent Horizons,"We describe a finite-difference method for locating apparent horizons and
illustrate its capabilities on boosted Kerr and Schwarzschild black holes. Our
model spacetime is given by the Kerr-Schild metric. We apply a Lorentz boost to
this spacetime metric and then carry out a 3+1 decomposition. The result is a
slicing of Kerr/Schwarzschild in which the black hole is propagated and Lorentz
contracted. We show that our method can locate distorted apparent horizons
efficiently and accurately.",0002076v1
2001-03-28,Area spectrum in Lorentz covariant loop gravity,"We use the manifestly Lorentz covariant canonical formalism to evaluate
eigenvalues of the area operator acting on Wilson lines. To this end we modify
the standard definition of the loop states to make it applicable to the present
case of non-commutative connections. The area operator is diagonalized by using
the usual shift ambiguity in definition of the connection. The eigenvalues are
then expressed through quadratic Casimir operators. No dependence on the
Immirzi parameter appears.",0103105v3
2001-06-15,Gravitational energy-momentum and the Hamiltonian formulation of the teleparallel gravity,"The transformation properties of the gravitational energy-momentum in the
teleparallel gravity are analyzed. It is proved that the gravitational
energy-momentum in the teleparallel gravity can be expressed in terms of the
Lorentz gauge potential, and therefore is not covariant under local Lorentz
transformations. On the other hand, it can also be expressed in terms of the
translation gauge field strength, and therefore is covariant under general
coordinate transformations. A simplified Hamiltonian formulation of the
teleparallel gravity is given. Its constraint algebra has the same structure as
that of general relativity, which indicates the equivalence between the
teleparallel gravity and general relativity in the Hamiltonian formulation.",0106053v1
2001-10-01,Restoration of Angular Lie Algebra Symmetries from a Covariant Hamiltonian,"The sO(3) and the Lorentz algebra symmetries breaking with gauge curvatures
are studied by means of a covariant Hamiltonian. The restoration of these
algebra symmetries in flat and curved spaces is performed and led to the
apparition of a monopole field. Then in the context of the Lorentz algebra we
consider an application to the gravitoelectromagnetism theory. In this last
case a qualitative relation giving a mass spectrum for dyons is established.",0110005v1
2002-07-22,Projected Spin Networks for Lorentz connection: Linking Spin Foams and Loop Gravity,"In the search for a covariant formulation for Loop Quantum Gravity, spin
foams have arised as the corresponding discrete space-time structure and, among
the different models, the Barrett-Crane model seems the most promising. Here,
we study its boundary states and introduce cylindrical functions on both the
Lorentz connection and the time normal to the studied hypersurface. We call
them projected cylindrical functions and we explain how they would naturally
arise in a covariant formulation of Loop Quantum Gravity.",0207084v1
2002-11-25,Relativity theory of clocks and rulers,"Special Relativity (SR) kinematics is derived from very intuitive
assumptions. Contrary to standard Einstein's derivation, no light signal is
used in the construction nor it is assumed to exist. Instead we postulate the
existence of two equivalence classes of physical objects: proportional clocks
and proportional rulers. Simple considerations lead to Lorentz kinematics as
one of three generic cases. The Lorentz case is characterized by the maximal
relative speed of physical objects. The two others are the Galilean and the
Euclidean cases.",0211079v1
2003-01-15,Lorentz contraction and accelerated systems,"The paper discusses the problem of the Lorentz contraction in accelerated
systems, in the context of the special theory of relativity. Equal proper
accelerations along different world lines are considered, showing the
differences arising when the world lines correspond to physically connected or
disconnected objects. In all cases the special theory of relativity proves to
be completely self-consistent",0301050v1
2003-03-01,"Comments on ``Improved limit on quantum-spacetime modifications of Lorentz symmetry from observations of gamma-ray blazars""","We address several criticisms by Amelino-Camelia of our recent analyses of
two observational constraints on Lorentz violation at order E/M_{Planck}. In
particular, we emphasize the role of effective field theory in our analysis of
synchrotron radiation, and we strengthen the justification for the constraint
coming from photon annihilation.",0303001v1
2003-10-02,Lorentz Invariance and the semiclassical approximation of loop quantum gravity,"It is shown that the field equations derived from an effective interaction
hamiltonian for Maxwell and gravitational fields in the semiclassical
approximation of loop quantum gravity using rotational invariant states (such
as weave states) are Lorentz invariant. To derive this result, which is in
agreement with the observational evidence, we use the geometrical properties of
the electromagnetic field.",0310014v2
2004-09-22,Canonical DSR,"For a certain example of a ""doubly special relativity theory"" the modified
space-time Lorentz transformations are obtained from momentum space
transformations by using canonical methods. In the sequel an energy-momentum
dependent space-time metric is constructed, which is essentially invariant
under the modified Lorentz transformations. By associating such a metric to
every Planck cell in space and the energy-momentum contained in it, a solution
of the problem of macroscopic bodies in doubly special relativity is suggested.",0409087v4
2004-11-14,Discrete quantum gravity: the Lorentz invariant weight for the Barrett-Crane model,"In a recent paper [1] we have constructed the spin and tensor representations
of SO(4) from which the invariant weight can be derived for the Barrett-Crane
model in quantum gravity. By analogy with the SO(4) group, we present the
complexified Clebsch-Gordan coefficients in order to construct the
Biedenharn-Dolginov function for the SO(3,1) group and the spherical function
as the Lorentz invariant weight of the model.",0411068v1
2004-11-19,On Loop Quantum Gravity Phenomenology and the Issue of Lorentz Invariance,"A simple model is constructed which allows to compute modified dispersion
relations with effects from loop quantum gravity. Different quantization
choices can be realized and their effects on the order of corrections studied
explicitly. A comparison with more involved semiclassical techniques shows that
there is agreement even at a quantitative level.
  Furthermore, by contrasting Hamiltonian and Lagrangian descriptions we show
that possible Lorentz symmetry violations may be blurred as an artifact of the
approximation scheme. Whether this is the case in a purely Hamiltonian analysis
can be resolved by an improvement in the effective semiclassical analysis.",0411101v1
2005-01-24,"Relativistic velocity space, Wigner rotation and Thomas precession","We develop a relativistic velocity space called \emph{rapidity space} from
the single assumption of Lorentz invariance, and use it to visualize and
calculate effects resulting from the successive application of non-colinear
Lorentz boosts. In particular, we show how rapidity space provides a geometric
approach to Wigner rotation and Thomas precession in the same way that
spacetime provides a geometrical approach to kinematic effects in special
relativity.",0501070v1
2005-10-29,Gravity from Local Lorentz Violation,"In general relativity, gravitational waves propagate at the speed of light,
and so gravitons are massless. The masslessness can be traced to symmetry under
diffeomorphisms. However, another elegant possibility exists: masslessness can
instead arise from spontaneous violation of local Lorentz invariance. We
construct the corresponding theory of gravity. It reproduces the
Einstein-Hilbert action of general relativity at low energies and temperatures.
Detectable signals occur for sensitive experiments, and potentially profound
implications emerge for our theoretical understanding of gravity.",0510124v1
2005-12-25,Lorentz Gauge Gravity and Induced Effective Theories,"We develop the gauge approach based on the Lorentz group to the gravity with
torsion. With a Lagrangian quadratic in curvature we show that the
Einstein-Hilbert action can be induced from a simple gauge model due to quantum
corrections of torsion via formation of a gravito-magnetic condensate. An
effective theory of cosmic knots at Planckian scale is proposed.",0512151v1
2006-02-24,ZM theory I: Introduction and Lorentz covariance,"We consider defining time as a function of a cyclical field, an abstraction
of a clock. The definition of time corresponds to a novel interpretation of the
relationship between space-time coordinates of observers at different locations
in space. As a first test of the utility of this definition, we show that it
leads to a Lorentz covariant description of space-time. This derivation of
Lorenz covariance provides a starting point for considering more general
constructions that relate to physical laws. The definition of time couples time
to space, making time not orthogonal to space, and making dynamics a result of
geometry, providing a vehicle for curved space-time theories that generalize
general relativity.",0602099v1
2006-05-01,Discreteness without symmetry breaking: a theorem,"This paper concerns sprinklings into Minkowski space (Poisson processes). It
proves that there exists no equivariant measurable map from sprinklings to
spacetime directions (even locally). Therefore, if a discrete structure is
associated to a sprinkling in an intrinsic manner, then the structure will not
pick out a preferred frame, locally or globally. This implies that the
discreteness of a sprinkled causal set will not give rise to ``Lorentz
breaking'' effects like modified dispersion relations. Another consequence is
that there is no way to associate a finite-valency graph to a sprinkling
consistently with Lorentz invariance.",0605006v1
2006-08-30,Towards a Covariant Loop Quantum Gravity,"We review the canonical analysis of the Palatini action without going to the
time gauge as in the standard derivation of Loop Quantum Gravity. This allows
to keep track of the Lorentz gauge symmetry and leads to a theory of Covariant
Loop Quantum Gravity. This new formulation does not suffer from the Immirzi
ambiguity, it has a continuous area spectrum and uses spin networks for the
Lorentz group. Finally, its dynamics can easily be related to Barrett-Crane
like spin foam models.",0608135v1
2007-02-05,Electro-weak Model within the framework of Lorentz gauge theory: Ashtekar variables?,"The Electroweak (EW) model is geometrized in the framework of a 5D gauge
theory of the Lorentz group, after the implementation of the Kaluza-Klein (KK)
paradigm. The possibility of introducing Ashtekar variables on a 5D KK manifold
is considered on the ground of its geometrical structure.",0702026v1
2005-12-30,Search for a Lorentz invariance violation in atmospheric neutrino oscillations using MACRO data,"The energy spectrum of neutrino-induced upward-going muons in MACRO was
analysed in terms of special relativity principles violating effects, keeping
standard mass-induced atmospheric neutrino oscillations as the dominant source
of nu_mu <--> nu_tau transitions. The data disfavour these exotic possibilities
even at a sub-dominant level, and stringent 90% C.L. limits are placed on the
Lorentz invariance violation parameters. These limits can also be
re-interpreted as upper bounds on the parameters describing violation of the
Equivalence Principle.",0512075v1
1996-02-07,2D Lorentzian Gravity as 2D Euclidean Gravity with Ising Spins,"We suggest a generalization of the dynamical triangulation approach to
quantum gravity with both timelike and spacelike edges, which can serve as a
toy model for quantum gravity in the Lorentz sector in two dimensions. It is
possible to consider the model in a purely Lorentzian sector or to relax this
constraint and allow local signature changing moves. We show that, with
suitable conventions, the model is equivalent to an Ising model coupled to 2D
Euclidean quantum gravity and conduct a preliminary numerical simulation of the
Lorentz sector.",9602009v1
1999-10-21,Lorentz gauge fixing and the Gribov problem: the fermion correlator in lattice compact QED with Wilson fermions,"For the Lorentz gauge the influence of Gribov copies on the fermion
propagator is investigated in quenched lattice compact QED. In the Coulomb
phase zero-momentum modes of the gauge fields are shown to be the main reason
for a significant deviation from ordinary perturbation theory.",9910037v1
1999-12-10,Fermionic correlators and zero-momentum modes in quenched lattice QED,"For the Lorentz gauge the influence of various Gribov gauge copies on the
fermion propagator is investigated in quenched compact lattice QED. Within the
Coulomb phase besides double Dirac sheets the zero-momentum modes of the gauge
fields are shown to cause the propagator to deviate strongly from the
perturbatively expected behaviour. The standard way to extract the fermion mass
fails. The recently proposed zero-momentum Lorentz gauge is demonstrated to
cure the problem.",9912017v1
1993-02-24,Temperature Dependence of Electric and Magnetic Gluon Condensates,"The contribution of Lorentz non-scalar operators to finite temperature
correlation functions is discussed. Using the local duality approach for the
one-pion matrix element of a product of two vector currents, the temperature
dependence of the average gluonic stress tensor is estimated in the chiral
limit to be $\langle{\bf E}^2 +{\bf B}^2\rangle_{T}=\frac{\pi^2}{10}bT^4$. At a
normalization point $\mu=0.5$ GeV we obtain $b\approx 1.1$. Together with the
known temperature dependence of the Lorentz scalar gluon condensate we are able
to infer $\langle{\bf E}^2\rangle_T$ and $\langle{\bf B}^2\rangle_T$ separately
in the low-temperature hadronic phase.",9302300v1
1993-05-04,Disoriented chiral condensate in (1+1) Lorentz-invariant geometry,"We consider isospin correlations of pions produced in a relativistic nuclear
collision, using an effective theory of the chiral order parameter. Our theory
has (1+1) Lorentz invariance as appropriate for the central rapidity region. We
argue that in certain regions of space correlations of the chiral order
parameter are described by the fixed point of the (1+1) WZNW model. The
corresponding anomalous dimension determines scaling of the probability to
observe a correlated cluster of pions with the size of this cluster in
rapidity. Though the maximal size of clusters for which this scaling is
applicable is cut off by pion mass, such clusters can still include
sufficiently many particles to make the scaling observable.",9305207v1
1993-09-17,Covariant Variable Front Quark Model,"We study the implications of Lorentz symmetry for hadronic structure by
formulating a manifestly covariant constituent quark model and find full
covariance for any Lorentz transformation requires utilizing a variable
quantization surface. Even though time-reversal invariance mandates a unique
orientation for the surface's direction, we investigated alternative choices
and find small numerical sensitivity to different directions. We also calculate
the static properties of the low lying pseudoscalar mesons and compare results
with existing noncovariant calculations. We conclude that there is a little
sensitivity of the calculated observables to the choice of the formalism,
provided relativity is properly implemented.",9309282v1
1995-09-04,Quantization of the tachyonic field and the preferred frame,"A consistent quantization scheme for imaginary-mass field is proposed. It is
related to an appropriate choice of the synchronization procedure (definition
of time), which guarantee an absolute causality in agreement with Lorentz
covariance. In that formulation a possible existence of field excitations
(tachyons) distinguish an inertial frame (tachyon privileged frame of
reference) {\em via} spontaneous breaking of the so called synchronization
group. In this scheme relativity principle is broken but Lorentz symmetry is
exactly preserved in agreement with local properties of the observed world.",9509219v2
1996-02-19,Lorentz Boosts as Squeeze Transformations and Coherence Problems,"The quark model and the parton model are known to be two different
manifestations of the same covariant entity. However, the interaction
amplitudes of partons are incoherent while they are coherent in the quark
model. According to Feynman, this is due to the dilation of the interaction
time among the quarks. We present a quantitative analysis of this time-dilation
problem using Lorentz boosts as squeeze transformations.",9602344v1
1997-03-30,Comments on Neutrino Tests of Special Relativity,"We point out that the assumption of Lorentz noninvariance examined recently
by Coleman and Glashow leads to neutrino flavor oscillations which are
phenomenologically equivalent to those obtained by assuming the neutrinos
violate the principle of equivalence. We then comment on the limits on Lorentz
noninvariance which can be derived from solar, atmospheric, and accelerator
neutrino experiments.",9703454v1
1998-06-24,Meson electromagnetic form factors in a relativistic quark model,"The main assumption of the model is that in soft processes mesons behave like
systems made of valence quarks and an effective vacuum- like field. The
4-momentum of the latter represents the relativistic generalization of the
potential energy. The electromagnetic form factors are expressed in terms of
the overlap integral of the initial and final wave functions written under the
form of Lorentz covariant distribution of quark momenta. The calculation is
fully Lorentz covariant and the form factors of the charged mesons are
normalized to unity at t=0.",9806463v1
1998-09-15,Test of Special Relativity and Equivalence Principle from Neutrinoless Double Beta Decay,"We generalize the formalism for testing Lorentz invariance and the
equivalence principle in the neutrino sector. While neutrino oscillation bounds
constrain the region of large mixing of the the weak and gravitational
eigenstates, we obtain new constraints on violations of Lorentz invariance and
the equivalence principle from neutrinoless double beta decay. These bounds
apply even in the case of no mixing and thus probe a totally unconstrained
region in the parameter space.",9809396v1
1998-10-08,Testing CPT and Lorentz Symmetry with Electrons and Positrons in Penning Traps,"We present a theoretical analysis of signals for CPT and Lorentz violation in
g-2 and charge-to-mass-ratio experiments on electrons and positrons in Penning
traps. Experiments measuring anomaly frequencies are found to be the most
sensitive to CPT violation. We find that the conventional figure of merit for
CPT breaking, involving the difference of the electron and positron g factors,
is inappropriate in this context, and an alternative is introduced. Bounds of
approximately one part in 10^{20} are attainable.",9810287v1
1999-01-20,Radiatively Induced Lorentz and CPT Violation in Electrodynamics,"In a nonperturbative formulation, radiative corrections arising from Lorentz
and CPT violation in the fermion sector induce a definite and nonzero
Chern-Simons addition to the electromagnetic action. If instead a perturbative
formulation is used, an infinite class of theories characterized by the value
of the Chern-Simons coefficient emerges at the quantum level.",9901358v1
1999-07-14,Induced Lorentz-Violating Chern-Simons Term in QED and Anomalous Contributions to Effective Action Expansions,"I present a unified formulation of anomalous contributions in quantum field
theories by calculating directly the effective action using the background
field and covariant-derivative expansion technique. I use this method to
determine uniquely the induced Chern-Simons term from the a Lorentz and CPT
violating term in fermion QED Lagrangian. The outstanding ambiguity is resolved
by properly taken into account the noncommutivity of $A$ and $\partial$. The
resulting vacuum polarization tensor acquires a non-Feynman diagram anomalous
contribution which accounts for the discrepancy between the present calculation
and the other calculations.",9907349v2
1999-07-30,Possible Spontaneous Breaking of Lorentz and CPT Symmetry,"One possible ramification of unified theories of nature such as string theory
that may underlie the conventional standard model is the possible spontaneous
breakdown of Lorentz and CPT symmetry. In this talk, the formalism for
inclusion of such effects into a low-energy effective field theory is
presented. An extension of the standard model that includes Lorentz- and
CPT-breaking terms is developed. The restriction of the standard model
extension to the QED sector is then discussed.",9907565v1
1999-08-19,Pair production and solutions of the wave equation for particles with arbitrary spin,"We investigate the theory of particles with arbitrary spin and anomalous
magnetic moment in the Lorentz representation (0,s)X(s,0), in an external
constant and uniform electromagnetic field. We obtain the density matrix of
free particles in pure spin states. The differential probability of pair
producing particles with arbitrary spin by an external constant uniform
electromagnetic field has been found using the exact solutions. We have
calculated the imaginary and real parts of the Lagrangian in an electromagnetic
field that takes into account vacuum polarization.",9908410v1
1999-09-28,Nonrelativistic Quantum Hamiltonian for Lorentz Violation,"A method is presented for deriving the nonrelativistic quantum hamiltonian of
a free massive fermion from the relativistic lagrangian of the
Lorentz-violating standard-model extension. It permits the extraction of terms
at arbitrary order in a Foldy-Wouthuysen expansion in inverse powers of the
mass. The quantum particle hamiltonian is obtained and its nonrelativistic
limit is given explicitly to third order.",9909542v1
1999-09-29,Signals for CPT and Lorentz Violation in Neutral-Meson Oscillations,"Experimental signals for indirect CPT violation in the neutral-meson systems
are studied in the context of a general CPT- and Lorentz-violating
standard-model extension. In this explicit theory, some CPT observables depend
on the meson momentum and exhibit diurnal variations. The consequences for CPT
tests vary significantly with the specific experimental scenario. The wide
range of possible effects is illustrated for two types of CPT experiment
presently underway, one involving boosted uncorrelated kaons and the other
involving unboosted correlated kaon pairs.",9909554v1
1999-11-16,Space-like meson electromagnetic form factor in a relativistic quark model,"The space-like electromagnetic form factor is expressed in terms of the
overlap integral of the initial and final meson wave functions written as
Lorentz covariant distributions of internal momenta. The meson constituents are
assumed to be valence quarks and an effective vacuum-like field. The momentum
of the latter represents a relativistic generalization of the potential energy
of the quark system. The calculation is fully Lorentz covariant and the form
factors of the charged mesons are normalized to unity at t=0. The numerical
results have been obtained by freezing the transverse degrees of freedom. We
found r_\pi^2=0.434 fm^2, r_{K^+}^2=0.333 fm^2, r_{K^0}^2=-0.069 fm^2 by taking
m_{u,d}=430 MeV, m_s=700 MeV.",9911377v1
1999-12-22,Bounds on CPT and Lorentz violation from experiments with kaons,"Possible signals for indirect CPT violation arising in experiments with
neutral kaons are considered in the context of a general CPT- and
Lorentz-violating standard-model extension. Certain CPT observables can depend
on the meson momentum and exhibit sidereal variations in time. Any
leading-order CPT violation would be controlled by four parameters that can be
separately constrained in appropriate experiments. Recent experiments bound
certain combinations of these parameters at the level of about $10^{-20}$ GeV.",9912456v1
2000-02-08,Exact Solutions of the Dirac Equation for Modified Coulombic Potentials,"Exact solutions are found to the Dirac equation for a combination of Lorentz
scalar and vector Coulombic potentials with additional non-Coulombic parts. An
appropriate linear combination of Lorentz scalar and vector non-Coulombic
potentials, with the scalar part dominating, can be chosen to give exact
analytic Dirac wave functions. The method works for the ground state or for the
lowest orbital state with l=j-{1/2}, for any j.",0002093v1
2000-02-10,New exotics in the double beta decay contributions zoo,"We discuss the potential of neutrinoless double beta decay for testing
Lorentz invariance and the weak equivalence principle as well as contributions
from dilaton exchange gravity in the neutrino sector. While neutrino
oscillation bounds constrain the region of large mixing of the weak and
gravitational eigenstates, we obtain new constraints on violations of Lorentz
invariance and the equivalence principle from neutrinoless double beta decay,
applying even in the case of no mixing. Double beta decay thus probes a totally
unconstrained region in the parameter space.",0002118v2
2000-03-08,Seesaw model and its Lorentz group formulation,"For two flavors, the seesaw matrix can be identified with a two dimensional
representation of the Lorentz group. This analogy facilitates the computation
of physical neutrino parameters, while giving an intuitive understanding of the
results. It is found that the induced mixing angle exhibits resonance behavior.
For maximal mixing, we derive a precise relation among the right-handed mixing
angle, the Majorana mass ratio, and their phase.",0003066v2
2000-04-17,No CPT Violation from Tilted Brane in Neutral Meson--Antimeson Systems,"Tilted brane in theories with large compact extra dimensions leads to
spontaneous symmetry breaking of the Lorentz and rotational invariance in four
dimensions, as shown by Dvali and Shifman. In this brief report, we point out
that the mentioned Lorentz symmetry breaking, although leading to the
CPT--violating interaction terms, cannot lead to the CPT violation in the
experimentally interesting $K$--${\bar K}$ and analogous systems.",0004155v1
2000-11-06,Lorentz Invariant Baryon CHPT,"Using the example of the elastic $\pi N$-amplitude, we discuss the low energy
expansion of QCD amplitudes in the sector with baryon number one. We show that
the chiral expansion of these amplitudes breaks down in certain regions of
phase space and present a framework which leads to a coherent description
throughout the low energy region, while keeping Lorentz and chiral invariance
manifest at every stage of the calculation. We explain how to construct a
representation of the pion nucleon scattering amplitude in terms of functions
of a single variable, which is valid to $O(q^4)$ and properly accounts for the
$\pi\pi$- and $\pi N$-cuts required by unitarity.",0011079v1
2000-11-09,Some exact solutions of the Dirac equation,"Exact analytic solutions are found to the Dirac equation for a combination of
Lorentz scalar and vector Coulombic potentials with additional non-Coulombic
parts. An appropriate linear combination of Lorentz scalar and vector
non-Coulombic potentials, with the scalar part dominating, can be chosen to
give exact analytic Dirac wave functions.",0011137v1
2000-11-13,Tests of Spacetime Symmetry with Particle Traps,"Lorentz and CPT symmetry have been tested at high precision in numerous
experiments. A general theoretical framework incorporating possible Lorentz and
CPT violation in an extension of the standard model of particle physics has
been developed. In this framework, analyses of several precision experiments
have been performed to find unsuppressed symmetry-violating signals. This paper
discusses features of the theory, presents results for trapped-particle
systems, and reports bounds from recent experiments.",0011162v2
2001-05-09,Self-consistent parametrization of the two-flavor isotropic color-superconducting ground state,"Lack of Lorentz invariance of QCD at finite quark chemical potential in
general implies the need of Lorentz non-invariant condensates for the
self-consistent description of the color-superconducting ground state.
Moreover, the spontaneous breakdown of color SU(3) in this state naturally
leads to the existence of SU(3) non-invariant non-superconducting expectation
values. We illustrate these observations by analyzing the properties of an
effective 2-flavor Nambu-Jona-Lasinio type Lagrangian and discuss the
possibility of color-superconducting states with effectively gapless fermionic
excitations. It turns out that the effect of condensates so far neglected can
yield new interesting phenomena.",0105079v1
2001-07-05,Proton Stability in Six Dimensions,"We show that Lorentz and gauge invariance explain the long proton lifetime
within the standard model in six dimensions. The baryon-number violating
operators have mass dimension 15 or higher. Upon TeV-scale compactification of
the two universal extra dimensions on a square $T^2/Z_2$ orbifold, a discrete
subgroup of the 6-dimensional Lorentz group continues to forbid dangerous
operators.",0107056v2
2001-10-16,Astrophysical Polarimetry of Cosmological Sources,"Kostelecky and Mewes have recently shown that sensitive constraints can be
placed on some aspects of Lorentz symmetry violation using certain astronomical
data on high-redshift sources. Here, I introduce that data in its astronomical
context, making it clear that these data are robust and accurate for their
purpose. In particular, I explain that spatially extended scattered light from
obscured quasars leads to a centrosymmetric scattering polarization, with
polarization position angle independent of wavelength. Evidentally, these
relationships aren't spoiled by propagation effects as the photons cross the
universe.",0110206v1
2001-11-12,Clock-Comparison Tests of Lorentz and CPT Symmetry in Space,"Clock-comparison experiments conducted in space can provide access to many
unmeasured coefficients for Lorentz and CPT violation. The orbital
configuration of a satellite platform and the relatively large velocities
attainable in a deep-space mission would permit a broad range of tests with
Planck-scale sensitivity.",0111141v1
2001-11-25,Probing the Planck Scale in Low-Energy Atomic Physics,"Experiments in atomic physics have exceptional sensitivity to small shifts in
energy in an atom, ion, or bound particle. They are particularly well suited to
search for unique low-energy signatures of new physics, including effects that
could originate from the Planck scale. A number of recent experiments have used
CPT and Lorentz violation as a candidate signal of new physics originating from
the Planck scale. A discussion of these experiments and their theoretical
implications is presented.",0111323v1
2002-08-07,Space-Based Searches for Lorentz and CPT Violation,"In this proceedings, a summary is presented of recent research investigating
ways in which high-precision atomic clocks on the International Space Station
could search for violations of Lorentz and CPT symmetry. Space-based searches
offer certain experimental advantages over Earth-based experiments
investigating these symmetries. The results are based on work published in
Physical Review Letters, volume 82, article 090801, 2002.",0208065v1
2002-09-06,Supersymmetric Noncommutative QED and Lorentz Violation,"We consider Lorentz-violating operators induced at the loop level in
softly-broken supersymmetric noncommutative QED. Dangerous operators forbidden
in the supersymmetric limit are generated via finite corrections, with the
scale of supersymmetry breaking serving as a gauge-invariant regulator. We
compare the most dangerous loop effects to those obtained in noncommutative
theories truncated by a momentum-space cutoff, and find significantly improved
bounds.",0209077v2
2002-10-31,The Origin of CP Violation,"Quantum field theory has been established on symmetries, but their
fundamentality could be limited as practical calculations of physical
observations are not based on interacting Lagrangian. The requirement of
Lorentz invariance on vacuum expectation values is contradicted by parity
violation with massive fermions and Lorentz violation of the approximation in
the standard model is proved. After alternative interpretation of quark mixing
and problems of CP violation are addressed, the composite properties of neural
meson will be suggested as origin of CP violation with possible experimental
tests. In conclusion, fundamental symmetry violation is still inconclusive due
to the limited theoretical assumptions and physical observations.",0211005v4
2002-11-29,Threshold configurations in the presence of Lorentz violating dispersion relations,"A general characterization of lower and upper threshold configurations for
two particle reactions is determined under the assumptions that the single
particle dispersion relations E(p) are rotationally invariant and monotonic in
p, and that energy and momentum are conserved and additive for multiple
particles. It is found that at a threshold the final particle momenta are
always parallel and the initial momenta are always anti-parallel. The
occurrence of new phenomena not occurring in a Lorentz invariant setting, such
as upper thresholds and asymmetric pair production thresholds, is explained,
and an illustrative example is given.",0211466v1
2003-02-04,Gauge and Lorentz Covariant Quark Propagator in an Arbitrary Gluon Field,"The quark propagator in presence of an arbitrary gluon field is calculated
gauge and Lorentz covariantly order by order in terms of powers of gluon field
and its derivatives. The result is independent of path connecting ends of
propagator and leading order result coincides with the exact propagator in the
trivial case of vanishing gluon field.",0302023v4
2003-02-04,Lorentz invariance relations among parton distributions revisited,"We revisit the derivation of the so-called Lorentz invariance relations
between parton distributions. In the most important cases these relations
involve twist-3 and transverse momentum dependent parton distributions. It is
shown that these relations are violated if the path-ordered exponential is
taken into account in the quark correlator.",0302028v2
2003-12-11,"Comment on ""Vacuum Photon Splitting in Lorentz-Violating Quantum Electrodynamics""","It has been argued in hep-ph/0212382 that there may be observable effects
from photon triple splitting in an extended version of quantum electrodynamics
with Lorentz violation in the fermion sector. The argument is based on an
analogy with photon splitting via collinear parametric down-conversion in
optically active crystals. In this Comment, we point out that the analogy is
misleading and that, at the order considered, the probability of on-shell
photon triple splitting is strictly zero.",0312153v1
2004-02-17,Hadron structure in manifestly Lorentz-invariant baryon chiral perturbation theory,"We briefly outline the so-called extended on-mass-shell renormalization
scheme for manifestly Lorentz-invariant baryon chiral perturbation theory which
provides a simple and consistent power counting for renormalized diagrams. We
comment on the role of chiral symmetry in the renormalization program and
discuss as applications the mass and the electromagnetic form factors of the
nucleon.",0402165v1
2004-05-13,"The Lorentz and CPT violating effects on the charged Higgs boson decays H^+ -> W^+ H^0 (h^0,A^0)","We study the decay widths of the processes H^+\to W^+ H^0 (h^0,A^0),
including the Lorentz violating effects and analyze the possible CPT violating
asymmetry arising from CPT odd coefficients. We observe that these effects are
too small to be detected, since the corresponding coefficients are highly
suppressed at the low energy scale.",0405119v2
2004-07-29,Testing Scenarios of Lorentz Symmetry Violation Generated at the Planck Scale,"Using new theoretical tools, which allow to better understand ultra-high
energy (UHE) dynamics, several patterns of Lorentz symmetry violation (LSV) are
studied and compared with experiment. It is claimed that quadratically deformed
relativistic kinematics (QDRK), where the parameter driving LSV varies like the
square of the energy scale, remains the best suited pattern to describe LSV
generated at the Planck scale. Implications of existing data are discussed and
prospects are presented having in mind next-generation experiments.",0407335v1
2004-08-25,The Cherenkov effect in Lorentz-violating vacua,"The emission of electromagnetic radiation by charges moving uniformly in a
Lorentz-violating vacuum is studied. The analysis is performed within the
classical Maxwell-Chern-Simons limit of the Standard-Model Extension (SME) and
confirms the possibility of a Cherenkov-type effect. In this context, various
properties of Cherenkov radiation including the rate, polarization, and
propagation features, are discussed, and the back-reaction on the charge is
investigated. An interpretation of this effect supplementing the conventional
one is given. The emerging physical picture leads to a universal methodology
for studying the Cherenkov effect in more general situations.",0408285v1
2004-12-07,Baryon masses and nucleon sigma terms in manifestly Lorentz-invariant baryon chiral perturbation theory,"We discuss the masses of the ground state baryon octet and the nucleon sigma
terms in the framework of manifestly Lorentz-invariant baryon chiral
perturbation theory. In order to obtain a consistent power counting for
renormalized diagrams the extended on-mass-shell renormalization scheme is
applied.",0412092v1
2005-09-19,Manifestly Lorentz-Invariant Baryon Chiral Perturbation Theory,"A successful effective field theory program requires besides the most general
effective Lagrangian a perturbative expansion scheme for observables in terms
of a consistent power counting method. We discuss a renormalization scheme for
manifestly Lorentz-invariant baryon chiral perturbation theory generating a
simple and consistent power counting for renormalized diagrams. The approach
may be used in an iterative procedure to renormalize higher-order loop diagrams
and also allows for implementing a consistent power counting when vector mesons
are explicitly included.",0509186v1
2006-02-03,Gauge and Lorentz Covariant Schwinger-Dyson Equation for Fermion Propagator in Arbitrary External Gauge Field,"A formalism of gauge and Lorentz covariant Schwinger-Dyson equation is built
up for fermion propagator in presence of arbitrary external gauge field within
ladder approximation. Different type external electromagnetic field dependent
trial solutions are investigated which spontaneously breaking chiral symmetry.",0602038v6
2006-02-11,Lorentz and CPT tests involving antiprotons,"Lorentz and CPT tests involving matter-antimatter comparisons at low
temperatures are discussed. SME predictions for transition frequencies in such
systems include both matter-antimatter differences and sidereal variations. In
hydrogen-antihydrogen spectroscopy, leading-order effects in a 1S-2S transition
as well as in a 1S Zeeman transition could exist that can be employed to obtain
clean constraints. Similarly, tight bounds can be determined from Penning-trap
experiments involving antiprotons.",0602097v1
2006-05-03,A Lorentz-Violating Origin of Neutrino Mass?,"We explore implications for neutrino physics of Very Special Relativity
(VSR), wherein the symmetry group of nature includes only a 4-parameter
subgroup of the Lorentz group. VSR can provide a natural origin to
lepton-number conserving neutrino masses without need for sterile
(right-handed) states. Neutrinoless double beta decay is forbidden if VSR is
solely responsible for neutrino masses. For ultra-relativistic neutrinos, such
as are ordinarily studied, VSR and conventional neutrino masses are
indistinguishable. However, we show that VSR effects can be significant near
the beta decay endpoint where neutrinos are not ultra-relativistic.",0605036v1
2006-08-02,Light baryon magnetic moments and N -> Delta gamma transition in a Lorentz covariant chiral quark approach,"We calculate magnetic moments of light baryons and N -> Delta gamma
transition characteristics using a manifestly Lorentz covariant chiral quark
approach for the study of baryons as bound states of constituent quarks dressed
by a cloud of pseudoscalar mesons.",0608015v2
2006-11-15,On the Radiatively Induced Lorentz and CPT Violating Chern-Simons Term,"The radiatively induced Lorentz and CPT violating Chern-Simons terms in QED
is calculated based on the recently developed loop regularization method [Y.L.
Wu, Int.J.Mod.Phys.A18 (2003) 5363, hep-th/0209021; Y.L. Wu, Mod.Phys.Lett.A19
(2004) 2191, hep-th/0311082] for quantum field theories. It enables us to make
general comments on the various results in literature and obtain a consistent
result when simultaneously combining the evaluation for the chiral anomaly
which has a unique form once the vector current is kept conserved.",0611199v3
2006-12-20,Electromagnetic properties of nucleons and hyperons in a Lorentz covariant quark model,"We calculate magnetic moments of nucleons and hyperons and N -> Delta + gamma
transition characteristics using a manifestly Lorentz covariant chiral quark
approach for the study of baryons as bound states of constituent quarks dressed
by a cloud of pseudoscalar mesons.",0612246v2
1992-01-11,The Superparticle and the Lorentz Group,"We present a unified group-theoretical framework for superparticle theories.
This explains the origin of the ``twistor-like'' variables that have been used
in trading the superparticle's $\kappa$-symmetry for worldline supersymmetry.
We show that these twistor-like variables naturally parametrise the coset space
${\cal G}/{\cal H}$, where $\cal G$ is the Lorentz group $SO^\uparrow(1,d-1)$
and $\cal H$ is its maximal subgroup. This space is a compact manifold, the
sphere $S^{d-2}$. Our group-theoretical construction gives the proper
covariantisation of a fixed light-cone frame and clarifies the relation between
target-space and worldline supersymmetries.",9201020v1
1992-06-12,Is Purity Eternal?,"Phenomenological and formal restrictions on the evolution of pure into mixed
states are discussed. In particular, it is argued that, if energy is conserved,
loss of purity is incompatible with the weakest possible form of Lorentz
covariance.",9206056v2
1992-10-15,A note on 2D chiral gravity and chiral bosons,"Quantization of two dimensional chiral matter coupled to gravity induces an
effective action for the zweibein field which is both Weyl and Lorentz
anomalous. Recently, the quantization of this induced action has been analyzed
in the light-cone gauge as well as in the conformal gauge. An apparent mismatch
between the results obtained in the two gauges is analyzed and resolved by
properly treating the Lorentz field as a chiral boson.",9210081v2
1992-11-04,Lorentz-Covariant Green-Schwarz Superstring Amplitudes,"In a recent paper, the BRST formalism for the gauge-fixed N=2 twistor-string
was used to calculate Green-Schwarz supersring scattering amplitudes with an
arbitrary number of loops and external massless states. Although the
gauge-fixing procedure preserved the worldsheet N=2 superconformal invariance
of the twistor-string, it broke the target-space SO(9,1) super-Poincar\'e
invariance down to an SU(4)xU(1) subgroup. In this paper, generators for the
SO(9,1) super-Poincar\'e transformations, as well as manifestly covariant
vertex operators, are explicitly constructed out of the gauge-fixed matter
fields. The earlier calculated amplitudes are then expressed in manifestly
Lorentz-covariant notation.",9211025v1
1993-03-22,Finiteness and Unitarity of Lorentz-Covariant Green-Schwarz Superstring Amplitudes,"In two recent papers, a new method was developed for calculating
ten-dimensional superstring amplitudes with an arbitrary number of loops and
external massless particles, and for expressing them in manifestly
Lorentz-invariant form. By explicitly checking for divergences when the Riemann
surface degenerates, these amplitudes are proven to be finite. By choosing
light-cone moduli for the surface and comparing with the light-cone
Green-Schwarz formalism, these amplitudes are proven to be unitary.",9303122v2
1993-09-14,Hermiticity and the Cohomology Condition in Topological Yang-Mills Theory,"The symmetries of the topological Yang-Mills theory are studied in the
Hamiltonian formalism and the generators of the twisted N=2 superPoincar\'e
algebra are explicitly constructed. Noting that the twisted Lorentz generators
do not generate the Lorentz symmetry of the theory, we relate the two by
extracting from the latter the twisted version of the internal SU(2) generator.
The hermiticity properties of the various generators are also considered
throughout, and the boost generators are found to be non-hermitian. We then
recover the BRST cohomology condition on physical states from representation
theory arguments.",9309081v1
1993-10-27,Elements of Reality and the Failure of the Product Rule Measurability of Commuting Observables,"The concept of ``elements of reality"" is analyzed within the framework of
quantum theory. It is shown that elements of reality fail to fulfill the
product rule. This is the core of recent proofs of the impossibility of a
Lorentz-invariant interpretation of quantum mechanics. A generalization and
extension of the concept of elements of reality is presented.
Lorentz-invariance is restored by giving up the product rule. The consequences
of giving up the ``and"" rule, which must be abandoned together with the product
rule, are discussed.",9310176v1
1994-02-16,Spontaneous Breakdown of the Lorentz Invariance,"We re-examine three-dimensional gauge theory with a Chern-Simons term in
which the Lorentz invariance is spontaneously broken by dynamical generation of
a magnetic field. A non-vanishing magnetic field leads, through the
Nambu-Goldstone theorem, to the decrease of zero-point energies of photons,
which accounts for a major part of the mechanism. The asymmetric spectral flow
plays an important role. The instability in pure Chern-Simons theory is also
noted.",9402096v1
1994-05-23,Lorentz Symmetry Breaking in Abelian Vector-Field Models with Wess-Zumino Interaction,"We consider the abelian vector-field models in the presence of the
Wess-Zumino interaction with the pseudoscalar matter. The occurence of the
dynamic breaking of Lorentz symmetry at classical and one-loop level is
described for massless and massive vector fields. This phenomenon appears to be
the non-perturbative counterpart of the perturbative renormalizability and/or
unitarity breaking in the chiral gauge theories.",9405147v1
1994-06-14,"Quantum Mechanics in Grassmann Space, Supersymmetry and Gravity","A particle which lives in a d-dimensional ordinary and a d-dimensional
Grassmann space manifests itself in an ordinary four-dimensional subspace as a
spinor, a scalar or a vector with charges. Operators of the Lorentz
transformations and translations in both spaces form the super- Poincar\' e
algebra. It is the super-Pauli-Ljubanski vector which generates spinors.
Vielbeins and spin connections with the Lorentz index larger than or equal to
five may manifest in a four-dimensional subspace as an electromagnetic, a weak
and a colour field.",9406083v1
1994-08-04,Non-Standard Fermion Propagators from Conformal Field Theory,"It is shown that Weyl spinors in 4D Minkowski space are composed of primary
fields of half-integer conformal weights. This yields representations of
fermionic 2-point functions in terms of correlators of primary fields with a
factorized transformation behavior under the Lorentz group. I employ this
observation to determine the general structure of the corresponding Lorentz
covariant correlators by methods similar to the methods employed in conformal
field theory to determine 2- and 3-point functions of primary fields. In
particular, the chiral symmetry breaking terms resemble fermionic 2-point
functions of 2D CFT up to a function of the product of momenta. The
construction also permits for the formulation of covariant meromorphy
constraints on spinors in 3+1 dimensions.",9408024v1
1994-09-02,Noncommutative Differential Calculus on the Kappa-Minkowski Space,"Following the construction of the $\kappa$-Minkowski space from the
bicrossproduct structure of the $\kappa$-Poincare group, we investigate
possible differential calculi on this noncommutative space. We discuss then the
action of the Lorentz quantum algebra and prove that there are no 4D
bicovariant differential calculi, which are Lorentz covariant. We show,
however, that there exist a five-dimensional differential calculus, which
satisfies both requirements. We study also a toy example of 2D
$\kappa$-Minkowski space and and we briefly discuss the main properties of its
differential calculi.",9409014v2
1994-11-16,$κ$-Deformation of Poincaré Superalgebra with Classical Lorentz Subalgebra and its Graded Bicrossproduct Structure,"The $\kappa$-deformed $D=4$ Poincar{\'e} superalgebra written in Hopf
superalgebra form is transformed to the basis with classical Lorentz subalgebra
generators. We show that in such a basis the $\kappa$-deformed $D=4$ Poincare
superalgebra can be written as graded bicrossproduct. We show that the
$\kappa$-deformed $D=4$ superalgebra acts covariantly on $\kappa$-deformed
chiral superspace.",9411115v1
1995-01-04,Gravitational Lorentz anomaly from the overlap formula in 2-dimensions,"In this letter we show that the overlap formulation of chiral gauge theories
correctly reproduces the gravitational Lorentz anomaly in 2-dimensions. This
formulation has been recently suggested as a solution to the fermion doubling
problem on the lattice. The well known response to general coordinate
transformations of the effective action of Weyl fermions coupled to gravity in
2-dimensions can also be recovered.",9501012v1
1995-03-28,Local gravitational supersymmetry of Chern-Simons theory in the vielbein formalism,"We discuss the Chern-Simons theory in three-dimensional curved space-time in
the vielbein formalism. Due to the additional presence of the local Lorentz
symmetry, beside the diffeomorphisms, we will include a local gravitational
supersymmetry (superdiffeomorphisms and super-Lorentz transformations), which
allows us to show the perturbative finiteness at all orders.",9503192v1
1995-08-17,Twistor Phase Space Dynamics and the Lorentz Force Equation,"Using Lorentz force equation as an input a Hamiltonian mechanics on the
non-projective two twistor phase space TxT is formulated. Such a construction
automatically reproduces dynamics of the intrinsic classical relativistic spin.
The charge appears as a dynamical variable. It is also shown that if the
classical relativistic spin function on TxT vanishes, the natural conformally
invariant symplectic structure on TxT reduces to the natural symplectic
structure on the cotangent bundle of the Kaluza-Klein space.",9508083v1
1996-02-13,Classical Tunneling from the Lorentz-Dirac Equation,"The classical equation of motion of a charged point particle, including its
radiation reaction, is described by the Lorentz-Dirac equation. We found a new
class of solutions that describe tunneling (in a completely classical
context!). For nonrelativistic electrons and a square barrier, the solution is
elementary and explicit. We show the persistance of the solution for smoother
potentials. For a large range of initial velocities, initial conditions may
leave a (discrete) ambiguity on the resulting motion.",9602066v1
1996-07-10,Gauging of Lorentz Group WZW Model by its Null Subgroup,"We consider the standard vector gauging of Lorentz group $ SO(3,1) $ WZW
model by its non-semisimple null Euclidean subgroup in two dimensions $ E(2) $.
The resultant effective action of the theory is seen to describe a one
dimensional bosonic field in the presence of external charge that we interpret
it as a Liouville field. Gauging a boosted $ SO(3) $ subgroup, we find that in
the limit of the large boost, the theory can be interpreted as an interacting
Toda theory. We also take the generalized non-standard bilinear form for
$SO(3,1) $ and gauge both $ SO(3) $ and $E(2)$ subgroups and discuss the
resultant theories.",9607084v1
1997-01-24,Generalized Action Principle and Superfield Equations of Motion for d=10 D-p-branes,"The action for the D=10 type II Dirichlet super-p-branes, which has been
obtained recently, is reconstructed in a more geometrical form involving
Lorentz harmonic variables. This new (Lorentz-harmonic) formulation possesses
kappa-symmetry in an irreducible form and is used as a basis for applying a
generalized action principle that provides the superfield equations of motion
and clarifies the geometrical nature of the kappa-symmetry of these models. The
case of a Dirichlet super-3-brane is considered in detail.",9701127v1
1997-04-05,Supersymmetric Lorentz-Covariant Hyperspaces and self-duality equations in dimensions greater than (4|4),"We generalise the notions of supersymmetry and superspace by allowing
generators and coordinates transforming according to more general Lorentz
representations than the spinorial and vectorial ones of standard lore. This
yields novel SO(3,1)-covariant superspaces, which we call hyperspaces, having
dimensionality greater than (4|4) of traditional super-Minkowski space. As an
application, we consider gauge fields on complexifications of these
superspaces; and extending the concept of self-duality, we obtain classes of
completely solvable equations analogous to the four-dimensional self-duality
equations.",9704036v1
1997-12-05,Hamiltonian Electric/Magnetic Duality and Lorentz Invariance,"In (3+1) Hamiltonian form, the conditions for the electric/magnetic
invariance of generic self-interacting gauge vector actions and the definition
of the duality generator are obvious. Instead, (3+1) actions are not
intrinsically Lorentz invariant. Imposing the Dirac-Schwinger stress tensor
commutator requirement to enforce the latter yields a differential constraint
on the Hamiltonian which translates into the usual Lagrangian form of the
duality invariance condition obeyed by Maxwell and Born-Infeld theories. We
also discuss covariance properties of some analogous scalar models.",9712067v1
1998-04-13,Spacetime locality in Sp(2) symmetric lagrangian formalism,"The existence of a local solution to the Sp(2) master equation for gauge
field theory is proven in the framework of perturbation theory and under
standard assumptions on regularity of the action. The arbitrariness of
solutions to the Sp(2) master equation is described, provided that they are
proper. It is also shown that the effective action can be chosen to be Sp(2)
and Lorentz invariant (under the additional assumption that the gauge
transformation generators are Lorentz tensors).",9804088v2
1998-07-30,Eleven-Dimensional Lorentz Symmetry from SUSY Quantum Mechanics,"The supermembrane in light-cone gauge gives rise to a supersymmetric quantum
mechanics system with SU(N) gauge symmetry when the group of area preserving
diffeomorphisms is suitably regulated. de Wit, Marquard and Nicolai showed how
eleven-dimensional Lorentz generators can be constructed from these degrees of
freedom at the classical level. In this paper, these considerations are
extended to the quantum level and it is shown the algebra closes to leading
nontrivial order at large N. A proposal is made for extending these results to
Matrix theory by realizing longitudinal boosts as large N renormalization group
transformations.",9807229v1
1998-09-08,Spinor representation of the general Lorentz group for spin 1/2 particles and CPT,"We show that the attempt to introduce all of the discrete space-time
transformations into the spinor representation of the Lorentz group as wholly
independent transformations (as in the vectorial representation) leads to an
8-component spinor representation in general. The first indications seem to
imply that CPT can be violated in this formulation without going outside of
field theory. However one needs further study to reach a final conclusion.",9809054v2
1998-12-15,Lorentz and CPT Violating Chern-Simons Term in the Derivative Expansion of QED,"We calculate by the method of dimensional regularization and derivative
expansion the one-loop effective action for a Dirac fermion with a
Lorentz-violating and CPT-odd kinetic term in the background of a gauge field.
We show that this term induces a Chern-Simons modification to Maxwell theory.
Some related issues are also discussed.",9812132v4
1999-01-22,Comparison of quantum field perturbation theory for the light front with the theory in lorentz coordinates,"The relationship between the perturbation theory in light-front coordinates
and Lorentz-covariant perturbation theory is investigated. A method for finding
the difference between separate terms of the corresponding series without their
explicit evaluation is proposed. A procedure of constructing additional
counter-terms to the canonical Hamiltonian that compensate this difference at
any finite order is proposed. For the Yukawa model, the light-front Hamiltonian
with all of these counter-terms is obtained in a closed form. Possible
application of this approach to gauge theories is discussed.",9901110v1
1999-04-15,Massless fields over $R^1 \times H^3$ space-time and coherent states for the Lorentz group,"The solutions of the arbitrary-spin massless wave equations over ${\bf R}^1
\times H^3$ space are obtained using the generalized coherent states for the
Lorentz group. The use of these solutions for the construction of invariant
propagators of quantized massless fields with an arbitrary spin over the ${\bf
R}^1 \times H^3$ space is considered. The expression for the scalar propagator
is obtained in the explicit form.",9904108v2
1999-08-26,Conformal Models of Thirring Type and the Affine Virasoro Construction,"We investigate a class of models in 1+1 dimensions with four fermion
interaction term. At each order of the perturbation expansion, the models are
ultraviolet finite and Lorentz non-invariant. We show that for certain
privileged values of the coupling constants, Lorentz symmetry is restored, and
indeed the model turns out to be conformally invariant. This phenomenon is both
quantum mechanical and non-perturbative.",9908176v3
1999-09-29,Regularization of QED by a generalized 't Hooft and Veltman method,"Generalizing the 't Hooft and Veltman method of unitary regulators, we
demonstrate for the first time the existence of local, Lorentz-invariant,
physically motivated Lagrangians of quantum-electrodynamic phenomena such that:
(i) Feynman diagrams are finite and equal the diagrams of QED but with
regularized propagators. (ii) N-point Green functions are causal. (iii)
S-matrix relates only electrons, positrons and photons, is unitary and
Lorentz-invariant, and conserves charge and total four-momentum.",9909207v2
2000-03-13,Realistic regularization of the QED Green functions,"Generalizing the 't Hooft and Veltman method of unitary regulators, we
demonstrate for the first time the existence of local, Lorentz-invariant,
physically motivated Lagrangians of quantum-electrodynamic phenomena such that:
(i) Feynman diagrams are finite and equal the diagrams of QED but with
regularized propagators. (ii) N-point Green functions are C-, P-, and
T-invariant up to a phase factor, Lorentz-invariant and causal. (iii) No
auxiliary particles or parameters are introduced.",0003094v2
2000-04-03,Field-Dependent BRS Tranformations and Correct Prescription for 1/(n.k)^p-Type Singularities in Axial Gauges,"The axial-gauge boson propagator contains 1/(n.k)^p-type singularities. These
singularities have generally been treated by inventing prescriptions for them.
We propose an alternative procedere for treating these singularities in the
path-integral formalism using the known way of treating the 1/k^{2n}-type
singularities in Lorentz-type gauges. For this purpose we use a finite
field-dependent BRS transformation that inerpolates between the Lorentz and
axial-type gauges. We arrive at the \epsilon-dependent tree propagator in
axial-type gauges.",0004007v1
2000-06-16,Some Comments of Vlasov-Liouville Equation and its Relation with Gravitational Field,"We discuss here the possibility to write the Liouville-Vlasov equation for
the Wigner-function of a spinor field coupled to a gauge field with field
strength tensor $F^{\mu\nu}$ in a curved space-time versus a local Lorentz
manifold (introduction of local Lorentz coordinates) with an appropriate
definition of a covariant derivative carried out using a spin connection
$B_{\mu}^{ab}(x)$.",0006127v1
2000-07-14,Elongation of Moving Noncommutative Solitons,"We discuss the characteristic properties of noncommutative solitons moving
with constant velocity. As noncommutativity breaks the Lorentz symmetry, the
shape of moving solitons is affected not just by the Lorentz contraction along
the velocity direction, but also sometimes by additional `elongation'
transverse to the velocity direction. We explore this in two examples:
noncommutative solitons in a scalar field theory on two spatial dimension and
`long stick' shaped noncommutative U(2) magnetic monopoles. However the
elongation factors of these two cases are different, and so not universal.",0007107v3
2000-10-18,Gravity as Lorentz Force,"The main object of the proposed theory is not a pseudometric, but a symmetric
affine connection on the Minkowski space. The coefficients of this connection
have one upper and two lower indices. These coefficients are symmetric with
respect to the permutation of the lower indices. We identify the convolution of
the connection coefficients with the vector - potential of the electromagnetic
field. Then the gravity is the Lorentz force of this electromagnetic field.",0010150v1
2000-10-24,Invariances of regularized QED diagrams,"We consider properties of connected diagrams with fermion-photon interaction
and such fermion and photon propagators and vertex function that the values of
these diagrams are finite. We establish the properties of these propagators and
vertex function that imply that these diagrams are invariant under C, P, T, CP,
CT, PT, or CPT transformations up to some phase factor common to each process.
We introduce eight new transformations related to Hermiticity and establish the
conditions under which they leave the tree transition probabilities invariant.
We determine such general Lorentz form-invariant fermion and photon propagators
and fermion-photon vertex functions that make diagrams Lorentz-invariant.",0010209v1
2000-12-05,Radiatively Induced Lorentz and CPT Violation in QED at Finite Temperature,"In this paper we evaluate the induced Lorentz and CPT violating Chern-Simons
term in the QED action at finite temperature. We do this using the method of
derivative expansion of fermion determinants. Also, we use the imaginary-time
formalism to calculate the temperature dependence of the Chern-Simons term",0012039v1
2001-01-29,Spontaneous Parity Violation in QCD At Finite Temperature: On the Inapplicability of the Vafa-Witten Theorem,"The generalization of the Vafa-Witten theorem ruling out parity violation to
QCD at finite temperature is considered. It is shown that this generalization
of the theorem rules out Lorentz-invariant parity violating operators from
spontaneously acquiring vacuum expectation values. However, it does not rule
out Lorentz-noninvariant parity-violating operators from acquiring expectation
values. Other situations where the theorem is inapplicable are also discussed.",0101197v2
2001-03-16,Quaternionic Lorentz group and Dirac equation,"We formulate Lorentz group representations in which ordinary complex numbers
are replaced by linear functions of real quaternions and introduce dotted and
undotted quaternionic one-dimensional spinors. To extend to parity the
space-time transformations, we combine these one-dimensional spinors into
bi-dimensional column vectors. From the transformation properties of the
two-component spinors, we derive a quaternionic chiral representation for the
space-time algebra. Finally, we obtain a quaternionic bi-dimensional version of
the Dirac equation.",0103129v1
2001-03-26,One-Loop Effective Action for the Extended Spinor Electrodynamics with Violation of Lorentz and CPT Symmetry,"If violation of Lorentz and CPT symmetry is introduced into the fermion
sector of conventional quantum electrodynamics, then the Chern-Simons term is
radiatively induced with finite nonzero coefficient, as well as the Maxwell
term is with logarithmically divergent one. The heat kernel expansion and the
proper time methods are used to determine the effective action in the one-loop
approximation unambiguously.",0103215v2
2001-03-31,Restoring Lorentz Invariance in Classical N=2 String,"We study classical N=2 string within the framework of the N=4 topological
formalism by Berkovits and Vafa. Special emphasis is put on the demonstration
of a classical equivalence of the theories and the construction of an action
for the N=4 topological string. The SO(2,2) Lorentz invariance missing in the
conventional Brink--Schwarz action for the N=2 string is restored in the N=4
topological action.",0104003v1
2001-06-04,Issues on Radiatively Induced Lorentz and CPT Violation in Quantum Electrodynamics,"Various ambiguous results on radiatively induced Lorentz and CPT violation in
quantum electrodynamics with a modified fermionic sector are reviewed and
possible explanations for this ambiguity appearing in the literature are
commentated. Furthermore, joint between stringent limit from astrophysical
observation and theoretical prediction on Lorenz and CPT violation is
discussed.",0106035v2
2001-07-19,Complete Lagrangian formulation for N=4 topological string,"We give a Lagrangian and display all local symmetries for N=4 topological
string by Berkovits, Vafa and Siegel, the latter previously known in the
superconformal gauge. Leading to a small N=4 superconformal algebra and
exhibiting the manifest Lorentz invariance the model is proposed to be a
framework for restoring the manifest Lorentz invariance in N=2 string
scattering amplitudes.",0107161v2
2001-10-05,Physical Instances of Noncommuting Coordinates,"Noncommuting spatial coordinates and fields can be realized in actual
physical situations. Plane wave solutions to noncommuting photodynamics exhibit
violaton of Lorentz invariance (special relativity).",0110057v1
2001-11-07,Propagation of a relativistic particle in terms of the unitary irreducible representations of the Lorentz group,"In a generalized Heisenberg/Schroedinger picture we use an invariant
space-time transformation to describe the motion of a relativistic particle. We
discuss the relation with the relativistic mechanics and find that the
propagation of the particle may be defined as space-time transition between
states with equal eigenvalues of the first and second Casimir operators of the
Lorentz algebra. In addition we use a vector on the light-cone. A massive
relativistic particle with spin 0 is considered. We also consider the
nonrelativistic limit.",0111063v2
2001-11-15,Toward an Infinite-component Field Theory with a Double Symmetry: Free Fields,"We begin a study of possibilities of describing hadrons in terms of monolocal
fields which transform as proper Lorentz group representations decomposable
into an infinite direct sum of finite-dimensional irreducible representations.
The additional requirement that the free-field Lagrangians be invariant under
the secondary symmetry transformations generated by the polar or the axial
four-vector representation of the orthochronous Lorentz group provides an
effective mechanism for selecting the class representations considered and
eliminating an infinite number of arbitrary constants allowed by the
relativistic invariance of the Lagrangians.",0111140v1
2002-01-30,Testing the Maldacena conjecture with SDLCQ,"We report on a test of the Maldacena conjecture. This string/field theory
correspondence has interesting applications. When combined with Rehren's
theorem, it has implications for issues concerning space-time structure and
Lorentz symmetry. Our results indicate that the conjecture is correct. We are
within 10-15% of the expected results, although the numerical evidence is not
yet decisive.",0201252v2
2002-08-12,Consistency in Perturbative Calculations and Radiatively Induced Lorentz and CPT Violations,"The origin of the radiatively induced Lorentz and CPT violations, in
perturbative evaluations, of an extended version of QED, is investigated. Using
a very general calculational method, concerning the manipulations and
calculations involving divergent amplitudes, we clearly identify the possible
sources of contributions for the violating terms. We show that consistency in
the perturbative calculations, in a broader sense, leaves no room for the
existence of radiatively induced contributions which is in accordance with what
was previously conjectured and recently advocated by some authors supported on
general arguments.",0208084v1
2002-10-08,"Quantum Gravity, Cosmology, (Liouville) Strings and Lorentz Invariance","I review some aspects of non-critical strings in connection with
Lorentz-Invariance violating approaches to quantum gravity. I also argue how
non-critical strings may provide a unifying framework where string Cosmology
and quantum gravity may be tackled together.",0210079v2
2002-12-01,On the effective lagrangian in spinor electrodynamics with added violation of Lorentz and CPT symmetries,"We consider quantum electrodynamics with additional coupling of spinor fields
to the space-time independent axial vector violating both Lorentz and CPT
symmetries. The Fock-Schwinger proper time method is used to calculate the
one-loop effective action up to the second order in the axial vector and to all
orders in the space-time independent electromagnetic field strength. We find
that the Chern-Simons term is not radiatively induced and that the effective
action is CPT invariant in the given approximation.",0212007v2
2003-04-02,Wigner's little group and Berry's phase for massless particles,"The ``little group'' for massless particles (namely, the Lorentz
transformations $\Lambda$ that leave a null vector invariant) is isomorphic to
the Euclidean group E2: translations and rotations in a plane. We show how to
obtain explicitly the rotation angle of E2 as a function of $\Lambda$ and we
relate that angle to Berry's topological phase. Some particles admit both signs
of helicity, and it is then possible to define a reduced density matrix for
their polarization. However, that density matrix is physically meaningless,
because it has no transformation law under the Lorentz group, even under
ordinary rotations.",0304017v1
2003-04-18,Supersymmetric Extension of the Lorentz and CPT-Violating Maxwell-Chern-Simons Model,"Focusing on gauge degrees of freedom specified by a 1+3 dimensions model
hosting a Maxwell term plus a Lorentz and CPT non-invariant Chern-Simons-like
contribution, we obtain a minimal extension of such a system to a
supersymmetric environment. We comment on resulting peculiar self-couplings for
the gauge sector, as well as on background contribution for gaugino masses.
Furthermore, a non-polynomial generalization is presented.",0304166v2
2003-11-11,Angular Symmetry Breaking Induced by Electromagnetic Field,"It is well known that velocities does not commute in presence of an
electromagnetic field. This property implies that angular algebra symmetries,
such as the sO(3) and Lorentz algebra symmetries, are broken. To restore these
angular symmetries we show the necessity of adding the Poincare momentum M to
the simple angular momentum L. These restorations performed succesively in a
flat space and in a curved space lead in each cases to the generation of a
Dirac magnetic monopole. In the particular case of the Lorentz algebra we
consider an application of our theory to the gravitoelectromagnetism. In this
last case we establish a qualitative relation giving the mass spectrum for
dyons.",0311097v1
2004-01-01,Quantization of Non-Critical Bosonic Open String Theory,"The theory of relativistic strings is considered in frames of Hamiltonian
formalism and Dirac's quantization procedure. A special gauge fixing condition
is formulated, related with the world sheet of the string in Lorentz-invariant
way. As a result, a new set of Lorentz-invariant canonical variables is
constructed, in which a consistent quantization of bosonic open string theory
could be done in Minkowski space-time of dimension $d=4$. The obtained quantum
theory possesses spin-mass spectrum with Regge-like behavior.",0401002v1
2004-05-24,Covariance of Time-Ordered Products Implies Local Commutativity of Fields,"We formulate Lorentz covariance of a quantum field theory in terms of
covariance of time-ordered products (or other Green's functions). This
formulation of Lorentz covariance implies spacelike local commutativity or
anticommutativity of fields, sometimes called microscopic causality or
microcausality. With this formulation microcausality does not have to be taken
as a separate assumption.",0405211v2
2004-06-07,An Abraham-Lorentz-like Equation for the Electron from the Worldline Variational Approach to QED,"The variational equation for the mean square displacement of the electron in
the polaron worldline approach to quenched QED can be cast into a form which
closely resembles the classical Abraham-Lorentz equation but without the
conceptual and practical diseases of the latter. The connection with delay
equations describing field retardation effects is also established. As
applications we solve this integro-differential equation numerically for
various values of the coupling constant and cut-off and re-derive the
variational approximation to the anomalous mass dimension of the electron found
recently.",0406062v1
2004-06-21,Lorentz invariance and unitarity in UV finite NCQFT,"Ultraviolet finite quantum field theory on even dimensional noncommutative
spacetime is formulated using coordinate coherent states. 2d spacetime is
foliated into families of orthogonal, non commutative, two-planes. Lorentz
invariance is recovered if one imposes a single non commutative parameter theta
in the theory. Unitarity is checked at the one-loop level and no violation is
found. Being UV finite NCQFT does not present any UV/IR mixing.",0406174v1
2004-12-21,Quantum Basis of Lorentz Symmetry,"An unconventional outlook on relationship between the quantum mechanics and
special relativity is proposed. We show that the two fundamental postulates of
quantum mechanics of Planck and de Broglie combined with the idea of comparison
scale (explained in the paper), are enough to introduce relativistic
description. We argue that Lorentz group is the symmetry group of quantum,
preferred frame description. We indicate that the departure from the orthodox
relativity postulate allows us, in easy way, to make special relativity and
quantum mechanics indivisible whole.",0412267v1
2004-12-29,The C Operator in PT-Symmetric Quantum Field Theory Transforms as a Lorentz Scalar,"A non-Hermitian Hamiltonian has a real positive spectrum and exhibits unitary
time evolution if the Hamiltonian possesses an unbroken PT (space-time
reflection) symmetry. The proof of unitarity requires the construction of a
linear operator called C. It is shown here that C is the complex extension of
the intrinsic parity operator and that the C operator transforms under the
Lorentz group as a scalar.",0412316v1
2005-05-25,Quantum Gravity induced Lorentz invariance violation in the Standard Model:hadrons,"The most important problem of fundamental Physics is the quantization of the
gravitational field. A main difficulty is the lack of available experimental
tests that discriminate among the theories proposed to quantize gravity.
Recently we showed that the Standard Model(SM) itself contains tiny Lorentz
invariance violation(LIV) terms coming from QG. All terms depend on one
arbitrary parameter $\alpha$ that set the scale of QG effects. In this paper we
obtain the LIV for mesons and nucleons and apply it to study several effects,
including the GZK anomaly.",0505228v1
2005-07-15,Quantum Theory in Accelerated Frames of Reference,"The observational basis of quantum theory in accelerated systems is studied.
The extension of Lorentz invariance to accelerated systems via the hypothesis
of locality is discussed and the limitations of this hypothesis are pointed
out. The nonlocal theory of accelerated observers is briefly described.
Moreover, the main observational aspects of Dirac's equation in noninertial
frames of reference are presented. The Galilean invariance of nonrelativistic
quantum mechanics and the mass superselection rule are examined in the light of
the invariance of physical laws under inhomogeneous Lorentz transformations.",0507157v1
2005-09-01,A Remark on Lorentz Violation at Finite Temperature,"We investigate the radiatively induced Chern-Simons-like term in
four-dimensional field theory at finite temperature. The Chern-Simons-like term
is temperature dependent and breaks the Lorentz and CPT symmetries. We find
that this term remains undetermined although it can be found unambiguously in
different regularization schemes at finite temperature.",0509008v2
2005-10-03,Interpretation of Lorentz boosts in conformally deformed special relativity theory,"Conformally deformed special relativity is mathematically consistent example
of a theory with two observer independent scales. As compare with recent DSR
proposals, it is formulated starting from the position space. In this work we
propose interpretation of Lorentz boosts of the model as transformations among
accelerated observers. We point further that the model can be considered as
relativistic version of MOND program and thus may be interesting in context of
dark matter problem.",0510015v2
2005-10-06,Gauge dependence of the infrared behaviour of massless QED_3,"Using the Zumino identities it is shown that in a class of non-local gauges,
massless QED_3 has an infrared behaviour of a conformal field theory with a
continuously varying anomalous dimension of the fermion. In the usual Lorentz
gauge, the fermion propagator falls off exponentially for a large separation,
but this apparent fermion mass is a gauge artifact.",0510055v3
2006-01-03,"A Lorentz-violating SO(3) model: discussing the unitarity, causality and the 't Hooft-Polyakov monopoles","In this paper, we extend the analysis of the Lorentz-violating Quantum
Eletrodynamics to the non-Abelian case: an SO(3) Yang-Mills Lagrangian with the
addition of the non-Abelian Chern-Simons-type term. We consider the spontaneous
symmetry breaking of the model and inspect its spectrum in order to check if
unitarity and causality are respected. An analysis of the topological structure
is also carried out and we show that a 't Hooft-Polyakov solution for monopoles
is still present.",0601015v2
2006-09-23,Non-local on-shell field redefinition for the SME,"This work instigates a study of non-local field mappings within the Lorentz-
and CPT-violating Standard-Model Extension (SME). An example of such a mapping
is constructed explicitly, and the conditions for the existence of its inverse
are investigated. It is demonstrated that the associated field redefinition can
remove b-type Lorentz violation from free SME fermions in certain situations.
These results are employed to obtain explicit expressions for the corresponding
Lorentz-breaking momentum-space eigenspinors and their orthogonality relations.",0609162v1
2006-10-09,Vector Solitons and Spontaneous Lorentz Violation Mechanism,"Taking a full 3D nonlinear vector matter field dynamics, a vector version of
a soliton state was found. The Nielsen-Olesen procedure was used in order to
derive a Lorentz-violation vector parameter which characterizes, via
Spontaneous Symmetry Breaking mechanism, the non-trivial vacuum. A stable
vortex configuration is obtained, and although the Chern-Simons-type terms do
not contribute to the value of the vortex core, the propagator analysis
suggests us the possibility of a contribution to the size of the vortex core
and to the growth of the field to achieve the asymptotic limit value with the
distance.",0610096v1
2006-12-15,Spacetime symmetries of the Lorentz-violating Maxwell-Chern-Simons model,"The spacetime symmetries of classical electrodynamics supplemented with a
Chern-Simons term that contains a constant nondynamical 4-vector are
investigated. In addition to translation invariance and the expected three
remaining Lorentz symmetries characterized by the little group of the external
vector, the model possesses an additional spacetime symmetry if the
nondynamical vector is lightlike. The conserved current associated with this
invariance is determined, and the symmetry structure arising from this
invariance and the usual little group ISO(2) is identified as SIM(2).",0612167v1
2007-01-24,N=1 Supersymetric Quantum Mechanics in a Scenario with Lorentz-Symmetry Violation,"We show in this paper that the dynamics of a non-relativistic particle with
spin, coupled to an external electromagnetic field and to a background that
breaks Lorentz symmetry, is naturally endowed with an N=1-supersymmetry. This
result is achieved in a superspace approach where the particle coordinates and
the spin degrees of freedom are components of the same supermultiplet.",0701230v1
2007-01-27,Noncommutative Coordinates Invariant under Rotations and Lorentz Transformations,"Dynamics with noncommutative coordinates invariant under three dimensional
rotations or, if time is included, under Lorentz transformations is developed.
These coordinates turn out to be the boost operators in SO(1,3) or in SO(2,3)
respectively. The noncommutativity is governed by a mass parameter $M$. The
principal results are: (i) a modification of the Heisenberg algebra for
distances smaller than 1/M, (ii) a lower limit, 1/M, on the localizability of
wave packets, (iii) discrete eigenvalues of coordinate operator in timelike
directions, and (iv) an upper limit, $M$, on the mass for which free field
equations have solutions. Possible restrictions on small black holes is
discussed.",0701253v2
2007-01-29,Supersymmetry in the Dirac equation for generalized Coulomb potential,"We propose a symmetry of the Dirac equation under the interchange of signs of
eigenvalues of the Dirac's $K$ operator. We show that the only potential which
obeys this requirement is the Coulomb one for both vector and scalar cases.
Spectrum of the Dirac Equation is obtained algebraically for arbitrary
combination of Lorentz-scalar and Lorentz-vector Coulomb potentials using the
Witten's Superalgebra approach. The results coincides with that, known from the
explicit solution of the Dirac equation.",0701259v1
2007-01-30,Cerenkov Radiation in a Lorentz-Violating and Birefringent Vacuum,"We calculate the emission spectrum for vacuum Cerenkov radiation in
Lorentz-violating extensions of electrodynamics. We develop an approach that
works equally well if the presence or the absence of birefringence. In addition
to confirming earlier work, we present the first calculation relevant to
Cerenkov radiation in the presence of a birefringent photon k_F term,
calculating the lower-energy part of the spectrum for that case.",0701270v2
2007-02-14,"Noncommutative spaces, the quantum of time and the Lorentz symmetry","We introduce three space-times that are discrete in time and compatible with
the Lorentz symmetry. We show that these spaces are no commutative, with
commutation relations similar to the relations of the Snyder and Yang spaces.
Furthermore, using a reparametrized relativistic particle we obtain a
realization of the Snyder type spaces and we construct an action for them.",0702113v1
2007-02-23,"Four-particle solutions to Baxter equation of SL(2,C) Heisenberg spin magnet for integer conformal Lorentz spin and their normalizability","The four reggeized gluon states for non-vanishing Lorentz conformal spin
$n_h$ are considered. To calculate their spectrum the Q-Baxter method is used.
As a result we describe normalizable trajectory-like states, which form
continuous spectrum, as well as discrete point-like solutions, which turn out
to be non-normalizable. The point-like solutions exist due to symmetry of the
Casimir operator where conformal weights $(h,\bar h) \to (h,1-\bar h)$.",0702191v1
2007-03-02,Topology of Vacuum Space-Time,"We present a topological classification of vacuum space-time. Assuming the
3-dimensional space allows a global chart, we show that the static vacuum
space-time of Einstein's theory can be classified by the knot topology
$\pi_3(S^3)=\pi_3(S^2)$. Viewing Einstein's theory as a gauge theory of Lorentz
group and identifying the gravitational connection as the gauge potential of
Lorentz group, we construct all possible vacuum gravitational connections which
give a vanishing curvature tensor. With this we show that the vacuum connection
has the knot topology, the same topology which describes the multiple vacua of
SU(2) gauge theory. We discuss the physical implications of our result in
quantum gravity.",0703016v1
2007-03-28,Spontaneous Lorentz Breaking and Massive Gravity,"We study a theory where the presence of an extra spin-two field coupled to
gravity gives rise to a phase with spontaneously broken Lorentz symmetry. In
this phase gravity is massive, and the Weak Equivalence Principle is respected.
The newtonian potentials are in general modified, but we identify an
non-perturbative symmetry that protects them. The gravitational waves sector
has a rich phenomenology: sources emit a combination of massless and massive
gravitons that propagate with distinct velocities and also oscillate. Since
their velocities differ from the speed of light, the time of flight difference
between gravitons and photons from a common source could be measured.",0703264v1
1994-11-03,Measures with infinite Lyapunov exponents for the periodic Lorentz gas,"In \cite{Ch91a} it was shown that the billiard ball map for the periodic
Lorentz gas has infinite topological entropy. In this article we study the set
of points with infinite Lyapunov exponents. Using the cell structure developed
in \cite{BSC90,Ku} we construct an ergodic invariant probability measure with
infinite topological entropy supported on this set. Since the topological
entropy is infinite this is a measure of maximal entropy. From the construction
it is clear that there many such measures can coexist on a single component of
topological transitivity. We also construct an ergodic invariant probability
measure with finite entropy which is supported on this set showing that
infinite exponents do not necessarily lead to infinite entropy.",9411237v1
1995-12-12,Isometric classification of norms in rearrangement-invariant function spaces,"Suppose that a real nonatomic function space on $[0,1]$ is equipped with two
re\-arran\-ge\-ment-invariant norms $\|\cdot\|$ and $|||\cdot|||$. We study the
question whether or not the fact that $(X,\|\cdot\|)$ is isometric to
$(X,|||\cdot|||)$ implies that $\|f\|= |||f|||$ for all $f$ in $X$. We show
that in strictly monotone Orlicz and Lorentz spaces this is equivalent to
asking whether or not the norms are defined by equal Orlicz functions, resp.
Lorentz weights.
  We show that the above implication holds true in most rearrangement-invariant
spaces, but we also identify a class of Orlicz spaces where it fails. We
provide a complete description of Orlicz functions $\varphi \neq\psi$ with the
property that $L_\varphi$ and $L_\psi$ are isometric.",9512206v1
1999-10-27,Tensor Products of Principal Unitary Representations of Quantum Lorentz Group and Askey-Wilson Polynomials,"We study the tensor product of principal unitary representations of the
quantum Lorentz group, prove a decomposition theorem and compute the associated
intertwiners. We show that these intertwiners can be expressed in terms of
complex continuations of 6j symbols of U_q(su(2)). These intertwiners are
expressed in terms of q-Racah polynomials and Askey-Wilson polynomials. The
orthogonality of these intertwiners imply some relation mixing these two
families of polynomials. The simplest of these relations is the orthogonality
of Askey-Wilson polynomials.",9910147v1
1999-12-29,Regularized derivatives in a 2-dimensional model of self-interacting fields with singular data,"The coupled Maxwell-Lorentz system describes feed-back action of
electromagnetic fields in classical electrodynamics. When applied to
point-charge sources (viewed as limiting cases of charged fluids) the resulting
nonlinear weakly hyperbolic system lies beyond the scope of classical
distribution theory. Using regularized derivatives in the framework of
Colombeau algebras of generalized functions we analyze a two-dimensional
analogue of the Maxwell-Lorentz system. After establishing existence and
uniqueness of solutions in this setting we derive some results on
distributional limits of solutions with $\delta$-like initial values.",9912219v1
2000-05-31,Flat Lorentz 3-Manifolds and Cocompact Fuchsian Groups,"This paper gives a new proof of a result of Geoff Mess that the linear
holonomy group of a complete flat Lorentz 3-manifold cannot be cocompact in
SO(2,1). The proof uses a signed marked Lorentzian length-spectrum invariant
developed by G.Margulis, reinterpreted in terms of deformations of hyperbolic
surfaces.",0005292v1
2003-07-15,"The extended future tube conjecture for SO(1,n)","Let C be the open upper light cone in $\mathbb R^{1+n}$ with respect to the
Lorentz product. The connected linear Lorentz group SO$_\mathbb R(1,n)^0$ acts
on C and therefore diagonally on the N-fold product $T^N$ where $T = \mathbb
R^{1+n} + iC \subset \mathbb C^{1+n}$. We prove that the extended future tube
SO$_\mathbb C(1,n) \cdot T^N$ is a domain of holomorphy.",0307202v1
2003-09-22,Local Limit Theorem for the Lorentz Process and Its Recurrence in the Plane,"For Young systems, i.e. for hyperbolic systems without/with singularities
satisfying Lai-Sang Young's axioms (which imply exponential decay of
correlation and the CLT) a local CLT is proven. In fact, a unified version of
the local CLT is found, covering among others the absolutely contionuous and
the arithmetic cases. For the planar Lorentz process with a finite horizon this
result implies a.) the local CLT and b.) the recurrence. For the latter case
($d=2$, finite horizon), combining the global CLT with abstract ergodic
theoretic ideas, K. Schmidt, and J.-P. Conze, could already establish
recurrence.",0309359v1
2004-12-09,The moduli space of embedded singly periodic maximal surfaces with isolated singularities in the Lorentz-Minkowski space $ł^3$,"We show that, up to some natural normalizations, the moduli space of singly
periodic complete embedded maximal surfaces in the Lorentz-Minkowski space
$\l^3=(\r^3,dx_1^2+dx_2^2-dx_3^2),$ with fundamental piece having a finite
number $(n+1)$ of singularities, is a real analytic manifold of dimension
$3n+4.$ The underlying topology agrees with the topology of uniform convergence
of graphs on compact subsets of $\{x_3=0\}.$",0412190v1
2005-01-12,Surfaces of annulus type with constant mean curvature in Lorentz-Minkowski space,"In this paper we solve the Plateau problem for spacelike surfaces with
constant mean curvature in Lorentz-Minkowski three-space $\l^3$ and spanning
two circular (axially symmetric) contours in parallel planes. We prove that
rotational symmetric surfaces are the only compact spacelike surfaces in $\l^3$
of constant mean curvature bounded by two concentric circles in parallel
planes. As conclusion, we characterize spacelike surfaces of revolution with
constant mean curvature as the only that either i) are the solutions of the
exterior Dirichlet problem for constant boundary data or ii) have an isolated
conical-type singularity.",0501188v1
2005-01-15,Isometric actions of Heisenberg groups on compact Lorentz manifolds,"We prove results toward classifying compact Lorentz manifolds on which
Heisenberg groups act isometrically. We give a general construction, leading to
a new example, of codimension-one actions--those for which the dimension of the
Heisenberg group is one less than the dimension of the manifold. The main
result is a classification of codimension-one actions, under the assumption
they are real-analytic.",0501235v2
2005-03-30,Marginally trapped surfaces in L4 and an extended Weierstrass-Bryant representation,"We give a conformal representation in terms of meromorphic data for a certain
class of spacelike surfaces in the Lorentz-Minkowski 4-space L^4 whose mean
curvature vector is either lightlike or zero at each point. This representation
extends simultaneously the Weierstrass representation for minimal surfaces in
Euclidean 3-space and for maximal surfaces in the Lorentz-Minkowski 3-space,
and the Bryant representation for mean curvature one surfaces in the hyperbolic
3-space and in the de Sitter 3-space.",0503702v1
2005-06-15,Stability of FD-TD schemes for Maxwell-Debye and Maxwell-Lorentz equations,"The stability of five finite difference-time domain (FD-TD) schemes coupling
Maxwell equations to Debye or Lorentz models have been analyzed in [1] (P.G.
Petropoulos, ""Stability and phase error analysis of FD-TD in dispersive
dielectrics"", IEEE Transactions on Antennas and Propagation, vol. 42, no. 1,
pp. 62--69, 1994), where numerical evidence for specific media have been used.
We use von Neumann analysis to give necessary and sufficient stability
conditions for these schemes for any medium, in accordance with the partial
results of [1].",0506289v1
2006-12-01,Relativistic Diffusion in Gödel's Universe,"K. G\""odel [G1] discovered his celebrated solution to Einstein equations in
1949. Additional contributions were made by Kundt [K] and Hawking-Ellis
([H-E],5.7). On the other hand, a general Lorentz invariant operator,
associated to the so-called ""relativistic diffusion'', and making sense in any
Lorentz manifold, was introduced by Franchi-Le Jan in [F-LJ]. Here is purposed
a first study of the relativistic diffusion in the framework of G\""odel's
universe, which contains matter.",0612020v2
1999-10-19,Exact energy eigenvalues of the generalized Dirac-Coulomb equation via a modified similarity transformation,"With the aid of a modified similarity transformation we obtained exact energy
eigenvalues of the generalized Dirac-Coulomb equation. This equation consists
of the time component of the Lorentz 4-vector potential V_v(r)=-A_1/r, and a
Lorentz scalar potential V_s(r)=-A_2/r. The transformed radial equations are so
simple that their solutions are inferred from the conventional solutions of the
Schrodinger equation.",9910030v1
2000-01-26,Non-linear connections on phase space and the Lorentz force law,"The equations of parallel transport for a non-linear connection on phase
space are examined. It is shown that, for a free-particle Lagrangian, the
connection term first-order in momentum reproduces the geodesic equation of
General Relativity and the term zeroth-order in the momentum reproduces the
Lorentz electromagnetic force law. Hence from one mathematical expression, a
non-linear parallel transport equation, one can derive the interaction laws for
both the gravitational and electromagnetic forces. These equations are free of
the difficulties associated with formalism of Weyl, which forms the basis for
the theory of Yang and Mills.",0001038v1
2002-01-14,The extended Lorentz force,"The Lorentz force equations provide a partial description of the geodesic
motion of a charged particle on a four-manifold. Under the hypothesis that
Maxwell's equations express symmetry properties of the Ricci tensor, the full
electromagnetic connection is determined. From this connection, the fourth
equation of the geodesic is derived. The validity of this fourth equation can
be determined by studying the decay of charged particles in an electric field.
Time will accelerate or decelerate relative to the proper time of a charged
particle moving in an electric field. Unstable charged particles moving in
opposite directions parallel to an electric field should exhibit different
decay rates.",0201027v1
2002-05-23,Lorentz transformation and vector field flows,"The parameter changes resulting from a combination of Lorentz transformation
are shown to form vector field flows. The exact, finite Thomas rotation angle
is determined and interpreted intuitively. Using phase portraits, the
parameters evolution can be clearly visualized. In addition to identifying the
fixed points, we obtain an analytic invariant, which correlates the evolution
of parameters.",0205036v2
2005-01-26,Hidden Consequence of Active Local Lorentz Invariance,"In this paper we investigate a hidden consequence of the hypothesis that
Lagrangians and field equations must be invariant under active local Lorentz
transformations. We show that this hypothesis implies in an equivalence between
spacetime structures with several curvature and torsion possibilities.",0501064v6
2000-02-28,Properties of Stationary Nonequilibrium States in the Thermostatted Lorentz Gas I: the One Particle System,"We study numerically and analytically the properties of the stationary state
of a particle moving under the influence of an electric field $\bE$ in a two
dimensional periodic Lorentz gas with the energy kept constant by a Gaussian
thermostat. Numerically the current appears to be a continuous function of
$\bE$ whose derivative varies very irregularly, possibly in a discontinuous
manner. We argue for the non differentibility of the current as a function of
$\bE$ utilizing a symbolic description of the dynamics based on the
discontinuities of the collision map. The decay of correlations and the
behavior of the diffusion constant are also investigated.",0002052v2
2000-03-15,The Burnett expansion of the periodic Lorentz gas,"Recently, stretched exponential decay of multiple correlations in the
periodic Lorentz gas has been used to show the convergence of a series of
correlations which has the physical interpretation as the fourth order Burnett
coefficient, a generalisation of the diffusion coefficient. Here the result is
extended to include all higher order Burnett coefficients, and give a plausible
argument that the expansion constructed from the Burnett coefficients has a
finite radius of convergence.",0003038v2
2001-05-08,Field dependent collision frequency of the two-dimensional driven random Lorentz gas,"In the field-driven, thermostatted Lorentz gas the collision frequency
increases with the magnitude of the applied field due to long-time
correlations. We study this effect with computer simulations and confirm the
presence of non-analytic terms in the field dependence of the collision
frequency as predicted by kinetic theory.",0105017v1
2001-06-05,Fluctuation formula for nonreversible dynamics in the thermostated Lorentz gas,"We investigate numerically the validity of the Gallavotti-Cohen fluctuation
formula in the two and three dimensional periodic Lorentz gas subjected to
constant electric and magnetic fields and thermostated by the Gaussian
isokinetic thermostat. The magnetic field breaks the time reversal symmetry,
and by choosing its orientation with respect to the lattice one can have either
a generalized reversing symmetry or no reversibility at all. Our results
indicate that the scaling property described by the fluctuation formula may be
approximately valid for large fluctuations even in the absence of
reversibility.",0106005v2
2002-10-25,Diffusive Lorentz gases and multibaker maps are compatible with irreversible thermodynamics,"We show that simple diffusive systems, such as the Lorentz gas and multibaker
maps are perfectly compatible with the laws of irreversible thermodynamics,
despite the fact that the moving particles, or their equivalents, in these
models do not interact with each other, and that the dynamics takes place in
low-dimensional phase spaces. The interaction of moving particles with
scatterers provides the dynamical mechanism responsible for an approach to
equilibrium, under appropriate conditions. This analysis provides a refutation
of the criticisms expressed recently by Cohen and Rondoni [Physica A 306 (2002)
117-128].",0210060v1
2004-01-25,Fluctuation Formula in the Nose-Hoover thermostated Lorentz gas,"In this paper we examine numerically the Gallavotti-Cohen fluctuation formula
for phase-space contraction rate and entropy production rate fluctuations in
the Nos\'e-Hoover thermostated periodic Lorentz gas. Our results indicate that
while the phase-space contraction rate fluctuations violate the fluctuation
formula near equilibrium states, the entropy production rate fluctuations obey
this formula near and far from equilibrium states as well.",0401036v2
1996-06-18,Anisotropic Transverse Flow and the HBT Correlation Function,"Utilizing the Lorentz invariance of the correlation function we study the
effects of anisotropic transverse flow on the HBT correlation function. In
particular we show that directed flow would evidence itself by non zero
``side--long'' and ``side--out'' terms in the correlation function. We also
show that the study of ratios of the correlation functions evaluated on
different event subsamples and/or different Lorentz systems provides
information on the source dimensions and velocity which could be less biased by
corrections of different kinds. We present a fitting technique appropriate for
HBT analysis which does not require binning and is especially useful for
multidimensional fitting.",9606033v1
1998-04-09,Relativistic Spin-Flavor States in Light Front Dynamics,"Orthonormal spin-flavor wave functions of Lorentz covariant quark models of
the Bakamjian-Thomas type are constructed for nucleon resonances. Three
different bases are presented. The manifestly Lorentz covariant Dirac-Melosh
basis is related to the Pauli-Melosh basis and the symmetrized Bargmann-Wigner
basis that are manifestly orthogonal.",9804021v1
1999-12-21,Large Lorentz Scalar and Vector Potentials in Nuclei,"In nonrelativistic models of nuclei, the underlying mass scales of low-energy
quantum chromodynamics (QCD) are largely hidden. In contrast, the covariant
formulations used in relativistic phenomenology manifest the QCD scales in
nuclei through large Lorentz scalar and four-vector nucleon self-energies. The
abundant and varied evidence in support of this connection and the consequences
are reviewed.",9912048v1
2004-10-27,Gauge dependence of calculations in relativistic Coulomb excitation,"Before a quantum-mechanical calculation involving electromagnetic
interactions is performed, a choice must be made of the gauge to be used in
expressing the potentials. If the calculation is done exactly, the observable
results it predicts will be independent of the choice of gauge. However, in
most practical calculations approximations are made, which can destroy the
gauge invariance of the predictions. We compare here the results of
coupled-channel time-dependent relativistic Coulomb excitation calculations, as
performed in either Lorentz or Coulomb gauges. We find significant differences
when the bombarding energy per nucleon is $\geq$ 2 GeV, which indicates that
the common practice of relying completely on the Lorentz gauge can be
dangerous.",0410112v1
2004-11-09,Recent Developments in the Lorentz Integral Transform (LIT) Method,"Recent results on electromagnetic reactions into the continuum of systems
with A from 3 to 7 are presented. They have been obtained using the Lorentz
Integral Transform (LIT) method. The method is shortly reviewed, emphasizing
how all the results, though obtained with the sole ingredient of the N-N
potential, contain the full complicated dynamics of the A-body system, both in
the initial and in the final states.",0411032v1
2005-05-11,$π^0$-Photoproduction on the deuteron via $Δ$-excitation using the Lorentz Integral Transform,"The Lorentz Integral Transform method (LIT) is extended to pion
photoproduction in the $\Delta$-resonance region. The main focus lies on the
solution of the conceptual difficulties which arise if energy dependent
operators for nucleon resonance excitations are considered. In order to
demonstrate the applicability of our approach, we calculate the inclusive cross
section for $\pi^0$-photoproduction off the deuteron within a simple pure
resonance model.",0505030v1
2006-10-12,Two-pion exchange NN potential from Lorentz-invariant $χ$EFT,"We outline the progress made in the past five years by the S\~ao Paulo group
in the development of a two-pion exchange nucleon-nucleon potential within a
Lorentz-invariant framework of (baryon) chiral perturbation theory.",0610053v1
2007-01-12,Electromagnetic reactions of few-body systems with the Lorentz integral transform method,"Various electromagnetic few-body break-up reactions into the many-body
continuum are calculated microscopically with the Lorentz integral transform
(LIT) method. For three- and four-body nuclei the nuclear Hamiltonian includes
two- and three- nucleon forces, while semirealistic interactions are used in
case of six- and seven-body systems. Comparisons with experimental data are
discussed. In addition various interesting aspects of the $^4$He
photodisintegration are studied: investigation of a tetrahedrical symmetry of
$^4$He and a test of non-local nuclear force models via the induced two-body
currents.",0701034v1
1996-10-23,Laying the ghost of the relativistic temperature transformation,"Using the Unruh-DeWitt detector, it is shown that a universal and continuous
Lorentz transformaion of temperature cannot exist for black-body radiation.
Since any valid Lorentz transformation of temperature must be able to deal with
black-body radiation, it is concluded that a universal and continuous
temperature transformation does not exist.",9610016v1
2000-05-31,"A gentle introduction to the foundations of classical electrodynamics: The meaning of the excitations (D,H) and the field strengths (E, B)","The axiomatic structure of the electromagnetic theory is outlined. We will
base classical electrodynamics on (1) electric charge conservation, (2) the
Lorentz force, (3) magnetic flux conservation, and (4) on the Maxwell-Lorentz
spacetime relations. This yields the Maxwell equations. The consequences will
be drawn, inter alia, for the interpretation and the dimension of the electric
and magnetic fields.",0005084v2
2000-07-14,Limit on Lorentz and CPT Violation of the Neutron Using a Two-Species Noble-Gas Maser,"A search for sidereal variations in the frequency difference between
co-located 129-Xe and 3-He Zeeman masers sets the most stringent limit to date
on leading-order Lorentz and CPT violation involving the neutron, consistent
with no effect at the level of 10^{-31} GeV.",0007049v1
2000-08-20,Pulsed SC Proton Linac,"The superconducting (SC) proton linac is proposed in the JAERI/KEK Joint
Project for a high-intensity proton accelerator in the energy region from 400
to 600 MeV. Highly stable fields in the SC cavities are required under the
dynamic Lorentz force detuning. A new model describing the dynamic Lorentz
detuning has been developed and the validity has been confirmed experimentally.
The model has been applied successfully to the rf control simulation of the SC
proton linac.",0008199v1
2000-12-06,Space-Time Exchange Invariance: Special Relativity as a Symmetry Principle,"Special relativity is reformulated as a symmetry property of space-time:
Space-Time Exchange Invariance. The additional hypothesis of spatial
homogeneity is then sufficient to derive the Lorentz transformation without
reference to the traditional form of the Principle of Special Relativity. The
kinematical version of the latter is shown to be a consequence of the Lorentz
transformation. As a dynamical application, the laws of electrodynamics and
magnetodynamics are derived from those of electrostatics and magnetostatics
respectively. The 4-vector nature of the electromagnetic potential plays a
crucial role in the last two derivations.",0012011v2
2000-12-20,A measurement of Lorentz Angle of radiation-hard Pixel Sensors,"Silicon pixel detectors developed to meet LHC requirements were tested in a
beam at CERN in the framework of the ATLAS collaboration. The experimental
behaviour of irradiated and not-irradiated sensors in a magnetic field is
discussed. The measurement of the Lorentz angle for these sensors at different
operating conditions is presented. A simple model of the charge drift in
silicon before and after irradiation is presented. The good agreement between
the model predictions and the experimental results is shown.",0012050v1
2001-03-14,On the Dependence of Electromagnetic Phenomena on the Relativity of Simultaneity,"Maxwell's equations hold in inertial reference frames in uniform
translational motion relative to one another. In conjunction with the Lorentz
coordinate transformation equations, the transformation equations for the
electric and magnetic field components in these reference frames can be
derived. As the derivation of the Lorentz coordinate transformation equations
depends on the relativity of simultaneity, and indeed on the argument on the
relativity of simultaneity, electromagnetic phenomena indicate that human
cognition is involved in the structure and functioning of the physical world.",0103037v1
2001-06-18,"The ""optical"" version of the barn-pole problem","We present diagrams and simple calculations for the apparent (i.e.
photographable) length of a moving ruler skimming the observer's position,
under three different classes of model. Special relativity's predictions in
this particular situation are the root-product average of the two more basic
first-order predictions generated by simple ""propagation timelag"" arguments. We
find that special relativity can legally predict either a photographable
Lorentz contraction or a photographable Lorentz expansion in the ""centred""
ruler, depending on whether our camera is at the ruler's ""apparent"" or
""official"" centre.",0106049v2
2001-11-06,On non-equivalence of Lorentz and Coulomb gauges within classical electrodynamics,"It is shown that the well-known procedure for proving the equivalence of the
expressions for the electric field calculated using the Lorentz and Coulomb
gauges is incorrect. The difference between the two gauges is due to the
difference in the speed of propagation of a disturbance of the scalar
potential. As an auxiliary result, it is proven that the solution for the
electric field cannot be obtained directly from the Maxwell equations, i.e.
without introducing the scalar and vector potentials.",0111017v1
2002-10-05,Deduction of Lorentz Transformation from the existence of absolute rest. Deduction of the speed of light in any frame of reference,"We begin by admitting the following: (i) there is a frame of reference where
the speed of light is the same in any direction (that speed is c) (ii) the
average speed of light on a two-way journey is c in every frame of reference.
  From this two premises we obtain an expression for the speed of light which
implies the speed of light depends on the motion of the frame of reference.
Also from this two premises solely we deduct Lorentz Transformation.",0210023v1
2003-03-21,Is the temperature as a Lorentz scalar?,"For the free Fermion gas at thermodynamic equilibrium, the temperature which
represents the averaged kinetic energy is demonstrated to have the proper
property which is invariant under the Lorentz boost, using the conceptions of
the relativistic quantum field theory and statistical physics. The
thermodynamic interaction is described by the coupling of particles with the
vacuum of a scalar pseudo boson which features a self-interaction. The various
measurement of the apparent temperature of a moving body is also investigated.",0303091v3
2003-04-08,Lorentz Force Correction and Radiation Frequency Property of Charged Particles in Magnetic Dipole,"By concern of compression of charge density field, the corrected Lorentz
force formula and consequent inference is presented. And further radiation
frequency property of an individual charge density field in magnetic dipole is
analyzed respectively for radiant property of the charged particle and the
emitted electromagnetic wave transfer property between the moving radiant
source and observer. As results, the behavior and radiation frequency property
of the electron beam in magnetic dipole is interpreted upon the individual's
behavior and property. At final, the potential application is put forward for
wider interest.",0304023v3
2004-03-26,The Space-Time Lorentz Transformation: Relativity of Simultaneity is Incompatible with Translational Invariance,"Observations of the apparent times and positions of moving clocks as
predicted by both `non-local' and `local' Lorentz Transformations are
considered. Only local transformations respect translational invariance. Such
transformations change temporal but not spatial intervals, so breaking space
time exchange symmetry and forbidding relativity of simultaneity and length
contraction. A satellite cesium clock experiment to test these predictions is
proposed.",0403127v2
2004-10-20,A Note on the Lorentz Transformations for Photon,"We discuss transormation laws of electric and magnetic fields under Lorentz
transformations, deduced from the Classical Field Theory. It is found that we
can connect the resulting expression for a bivector formed with those fields,
with the expression deduced from the Wigner transformation rules for spin-1
functions of massive particles. This mass parameter should be interpreted
because the constancy of speed of light forbids the existence of the photon
mass.",0410169v1
2004-11-03,On the motion of a classical charged particle,"We show that the Lorentz-Dirac equation is not an unavoidable consequence of
energy-momentum conservation for a point charge. What follows solely from
conservation laws is a less restrictive equation already obtained by Honig and
Szamosi. The latter is not properly an equation of motion because, as it
contains an extra scalar variable, it does not determine the future evolution
of the charge. We show that a supplementary constitutive relation can be added
so that the motion is determined and free from the troubles that are customary
in Lorentz-Dirac equation, i. e. preacceleration and runaways.",0411032v1
2004-12-07,Propagation of the main signal in a dispersive Lorentz medium,"Evolution of the main signal in a Lorentz dispersive medium is considered.
The signal propagating in the medium is excited by a sine-modulated pulse
signal, with its envelope described by a hyperbolic tangent function. Both
uniform and non-uniform asymptotic representations for the signal are found. It
is shown when the uniform representation can be reduced to the non-uniform one.
The results obtained are illustrated with a numerical example.",0412045v1
2004-12-10,On Sommerfeld precursor in a Lorentz medium,"A one-dimensional electromagnetic problem of Sommerfeld precursor evolution,
resulting from a finite rise-time signal excitation in a dispersive Lorentz
medium is considered. The effect of the initial signal rate of growth as well
as of the medium dumping on the precursor shape and its magnitude is discussed.
The analysis applied is based on an approach employing uniform asymptotic
expansions. In addition, new approximate formulas are given for the location of
the distant saddle points which affect local frequency and dumping of the
precursor. The results obtained are illustrated numerically and compared with
the results known from the literature.",0412065v1
2005-01-10,The Local Space-Time Lorentz Transformation: a New Formulation of Special Relativity Compatible with Translational Invariance,"The apparent times and positions of moving clocks as predicted by both
`non-local' and `local' Lorentz Transformations are considered. Only local
transformations respect translational invariance. Such transformations change
temporal but not spatial intervals, so breaking space-time exchange symmetry
and forbidding relativity of simultaneity and length contraction. Two
satellite-borne experiments to test these predictions are proposed.",0501043v3
2005-01-25,Einstein's concept of a clock and clock paradox,"A geometric illustration of the Lorentz transformations is given. According
to similarity between space and time and correspondence between a ruler and a
clock, like the division number in a moving ruler, the tick number of a moving
clock is independent of its relative speed and hence invariant under the
Lorentz transformations. So the hand of the moving clock never runs slow but
the time interval between its two consecutive ticks contracts. Thus it is
Einstein's concept of slowing of the hands of moving clocks to create the clock
paradox or twin paradox. Regrettably, the concept of the clock that Einstein
retained is equivalent to Newton's concept of absolute time that he rejected.
This is a blemish in Einstein's otherwise perfect special relativity.",0501131v1
2005-03-31,How Ampere could have derived the Lorentz Transformations,"Lorentz Transformations of Special Relativity are derived from two
postulates: the first is the Principle of Relativity, while the postulate of
invariance of the velocity of light, used in usual derivations, is replaced by
a law of lectro-magneto-statics and invariance of electrical charge. Our
derivation does not require the assumption of regularity conditions of the
Transformations, such as linearity and continuity required by other
derivations. The level of the needed mathematics and physical concepts makes
the proposed derivation suitable for Secondary School.",0503227v1
2005-06-29,Singularity dynamics: Action and Reaction,"The interaction between singular and regular fields is considered for
Lorentz-invariant scalar and vector wave equations. The singular field is
generated by a Dirac source term. Its dynamics are deduced from the total field
Lagrangian. At non-relativistic speeds, the resulting equations of motion are
those of a mass in a scalar potential. Using this method we deduce the
relationship between source amplitude (scalar gravitational mass) and dynamic
mass (inertial mass). Generalising this method implies Lorentz forces for
charge singularities in the electromagnetic field and describes the dynamics
and interaction of hypothetical magnetic monopoles.",0506209v1
2005-08-23,(not quite) Theoretical Proof of the Lorentz Force Formula,"There is actually a mistake in this paper, but it is still a nice try worth a
read. It is (not quite) proved that within the framework of Special Relativity,
a force exerted on a \emph{classical particle} by a field must be of the form
$\yv{E}+\yv{v}\times\yv{B}$, the Lorentz force form. The proof makes use of an
action principle in which the action is the sum of a free particle part, and an
interaction part.",0508169v4
2005-10-07,Corrections to the energy levels of a spin-zero particle bound in a strong field,"Formulas for the corrections to the energy levels and wave functions of a
spin-zero particle bound in a strong field are derived. General case of the sum
of a Lorentz-scalar potential and zero component of a Lorentz-vector potential
is considered. The forms of the corrections differ essentially from those for
spin-1/2 particles. As an example of application of our results, we evaluated
the electric polarizability of a ground state of a spin-zero particle bound in
a strong Coulomb field.",0510056v1
2005-10-14,Is a Plasma Diamagnetic?,"Classical plasmas in thermodynamic equilibrium should be neither para- nor
diamagnetic due to the action of the Lorentz force. Magnetic confinement,
however, is based on the observed diamagnetism of laboratory plasmas. The
apparent paradox is investigated on the basis of the resistive
magneto-hydrodynamic equations. It is found that, at least in simple plasma
configurations, these equations do not permit a solution, i. e. the paradox
cannot be resolved. It seems that the Lorentz force is a test-particle
approximation which is not suitable to describe the interaction of moving
particles in agreement with the conservation of energy.",0510139v2
2006-05-11,Reflection of light from a moving mirror: derivation of the relativistic Doppler formula without Lorentz transformations,"A special case of the relativistic Doppler effect, which occurs when light
reflects from a moving mirror, is discussed. The classic formula for the
Doppler shift is derived in a fully non-relativistic fashion using basic facts
from geometry. The derivation does not involve Lorentz transformations, length
contractions and time dilations, and therefore is conceptually simpler than the
standard derivations in physics textbooks. This discussion can be useful for
teaching introductory physics and also for understanding the foundations of
special relativity.",0605100v1
2006-06-12,The simplest derivation of the Lorentz transformation,"Starting from the well-known light-clock thought experiment to derive time
dilation and length contraction, it is shown that finding the Lorentz
Transformation requires nothing more than the most trivial vector addition
formula. The form which is obtaine for the L.T. allows an easy derivation of
the velocity and acceleration transformations which are also given.",0606103v4
2006-07-07,Three species of neutrinos Six flavors quarks and three gluons. (Consequences or coincidences?),"A linear real 4-dimensional space structured by Lorentz metric implies six
2-dimensional singular subspaces and three independent 1-dimensional subspaces
called radicals. If we consider meaningful to use them as representing six
quarks and three gluons, respectively, then antiquarcs and antigluons are
implicitly defined. Since Lorentz metric is not singular, the dual metric space
of X denoted in general by X* is well defined and follow the structure of X.
The peculiar properties of singular subspaces guaranty what we call
confinement. For precision, we define first what means free system using the
structure of X and X*and thereby how X are lodging six quarks and three gluons.",0607069v2
2007-01-21,The Lorentz-Dirac and Dirac Equations,"It is well known that the Classical theory of the electron reached the limits
of its description at time intervals of the order of $10^{-23} secs$, that is
the Compton time. It is widely believed that below these time intervals
Classical Electrodynamics doesn't work and that a Quantum description is
required. Using the Lorentz Dirac and the Dirac equations of the electron, we
point out that in fact there is a convergence of the two descriptions at the
Compton scale.",0701237v1
2007-03-08,A new kind of boundary layer flow due to Lorentz forces,"In this paper we present a new kind of boundary layer flow produced by an
electromagnetic Lorentz force which acts parallel to the plate in an
electrically conductive fluid. The plate is motionless and the ambient fluid
stagnant. This flow is equivalent to the classical free convective flow along a
vertical plate. The boundary layer equations are transformed to non-dimensional
form and a new dimensionless number is introduced which is equivalent to the
Grashof number. The transformed boundary layer equations are solved with the
finite difference method and the presented results include values of the
friction coefficient and velocity profiles.",0703094v1
2007-03-19,Translational invariance and the space-time Lorentz transformation with arbitrary spatial coordinates,"Translational invariance requires that physical predictions are independent
of the choice of spatial coordinate system used. The time dilatation effect of
special relativity is shown to manifestly respect this invariance.
Consideration of the space-time Lorentz transformation with arbitrary spatial
coordinates shows that the spurious `length contraction' and `relativity of
simultaneity' effects --the latter violating translational invariance-- result
from the use of a different spatial coordinate system to describe each of two
spatially separated clocks at rest in a common inertial frame",0703185v3
1995-01-25,Lorentz Transformations as Lie-Poisson Symmetries,"We write down the Poisson structure for a relativistic particle where the
Lorentz group does not act canonically, but instead as a Poisson-Lie group. In
so doing we obtain the classical limit of a particle moving on a noncommutative
space possessing $SL_q(2,C)$ invariance. We show that if the standard mass
shell constraint is chosen for the Hamiltonian function, then the particle
interacts with the space-time. We solve for the trajectory and find that it
originates and terminates at singularities.",9501026v1
1996-01-23,Double quantum groups and Iwasawa decomposition,"The double quantum groups are the Hopf algebras underlying the complex
quantum groups of which the simplest example is the quantum Lorentz group. They
are non- standard quantizations of the double group $G \times G$. We construct
a corresponding quantized universal enveloping algebra (QUE) and prove that the
pairing between a quantum double group and its QUE is nondegenerate. We analyze
the representation theory of these double quantum groups, give a detailed
version of the Iwasawa decomposition proved by Podles and Woronowicz for the
quantum Lorentz group, and show that they are noetherian algebras. Finally we
outline a construction of more general non-standard quantum groups using
quantum double groups and their generalizations.",9601024v1
1998-12-15,Radiation reaction in quantum mechanics,"The Lorentz-Dirac radiation reaction formula predicts that the position shift
of a charged particle due to the radiation reaction is of first order in
acceleration if it undergoes a small acceleration. A semi-classical calculation
shows that this is impossible at least if the acceleration is due to a
time-independent potential. Thus, the Lorentz-Dirac formula gives an incorrect
classical limit in this situation. The correct classical limit of the position
shift at the lowest order in acceleration is obtained by assuming that the
energy loss at each time is given by the Larmor formula.",9812036v1
1999-06-04,"Maxwell Duality, Lorentz Invariance, and Topological Phase","We discuss the Maxwell electromagnetic duality relations between the
Aharonov-Bohm, Aharonov-Casher, and He-McKellar-Wilkens topological phases,
which allows a unified description of all three phenomena. We also elucidate
Lorentz transformations that allow these effects to be understood in an
intuitive fashion in the rest frame of the moving quantum particle. Finally, we
propose two experimental schemes for measuring the He-McKellar-Wilkens phase.",9906016v3
2000-09-25,Poincaré covariance of relativistic quantum position,"A great number of problems of relativistic position in quantum mechanics are
due to the use of coordinates which are not inherent objects of spacetime,
cause unnecessary complications and can lead to misconceptions. We apply a
coordinate-free approach to rule out such problems. Thus it will be clear, for
example, that the Lorentz covariance of position, required usually on the
analogy of Lorentz covariance of spacetime coordinates, is not well posed and
we show that in a right setting the Newton--Wigner position is Poincar\'e
covariant, in contradiction with the usual assertions.",0009102v1
2001-06-14,Lorentz transformations of open systems,"We consider open dynamical systems, subject to external interventions by
agents that are not completely described by the theory (classical or quantal).
These interventions are localized in regions that are relatively spacelike.
Under these circumstances, no relativistic transformation law exists that
relates the descriptions of the physical system by observers in relative
motion. Still, physical laws are the same in all Lorentz frames.",0106079v2
2002-02-19,Relativistically invariant extension of the de Broglie-Bohm theory of quantum mechanics,"We show that quantum mechanics can be given a Lorentz-invariant realistic
interpretation by applying our recently proposed relativistic extension of the
de Broglie-Bohm theory to deduce non-locally correlated, Lorentz-invariant
individual particle motions for the Einstein-Podolsky-Rosen experiment and the
double-interferometer experiment proposed by Horne, Shimony and Zeilinger.",0202104v2
2004-06-29,Communicating continuous quantum variables between different Lorentz frames,"We show how to communicate Heisenberg-limited continuous (quantum) variables
between Alice and Bob in the case where they occupy two inertial reference
frames that differ by an unknown Lorentz boost. There are two effects that need
to be overcome: the Doppler shift and the absence of synchronized clocks.
Furthermore, we show how Alice and Bob can share Doppler-invariant
entanglement, and we demonstrate that the protocol is robust under photon loss.",0406219v2
2004-12-24,Why is Schrodinger's Equation Linear?,"Information-theoretic arguments are used to obtain a link between the
accurate linearity of Schrodinger's equation and Lorentz invariance: A possible
violation of the latter at short distances would imply the appearance of
nonlinear corrections to quantum theory. Nonlinear corrections can also appear
in a Lorentz invariant theory in the form of higher derivative terms that are
determined by a length scale, possibly the Planck length. It is suggested that
the best place to look for evidence of such quantum nonlinear effects is in
neutrino physics and cosmology.",0412192v2
2005-07-06,Lorentz-covariant reduced spin density matrix and EPR-Bohm correlations,"We show that it is possible to define a Lorentz-covariant reduced spin
density matrix for massive particles. Such a matrix allows one to calculate the
mean values of observables connected with spin measurements (average
polarizations). Moreover, it contains not only information about polarization
of the particle but also information about its average kinematical state. We
also use our formalism to calculate the correlation function in the
Einstein--Podolsky--Rosen--Bohm type experiment with massive relativistic
particles.",0507056v1
2005-12-11,Relativity and Lorentz Invariance of Entanglement Distillability,"We study entanglement distillability of bipartite mixed spin states under
Wigner rotations induced by Lorentz transformations. We define weak and strong
criteria for relativistic isoentangled and isodistillable states to
characterize relative and invariant behavior of entanglement and
distillability. We exemplify these criteria in the context of Werner states,
where fully analytical methods can be achieved and all relevant cases
presented.",0512081v2
2006-12-12,Lorentz-covariant deformed algebra with minimal length,"The $D$-dimensional two-parameter deformed algebra with minimal length
introduced by Kempf is generalized to a Lorentz-covariant algebra describing a
($D+1$)-dimensional quantized space-time. For D=3, it includes Snyder algebra
as a special case. The deformed Poincar\'e transformations leaving the algebra
invariant are identified. Uncertainty relations are studied. In the case of D=1
and one nonvanishing parameter, the bound-state energy spectrum and
wavefunctions of the Dirac oscillator are exactly obtained.",0612093v1
2006-12-15,Intrinsic Regularization in a Lorentz invariant non-orthogonal Euclidean Space,"It is shown that the Lorentz transformations can be derived for a
non-orthogonal Euclidean space. In this geometry one finds the same relations
of special relativity as the ones known from the orthogonal Minkowski space. In
order to illustrate the advantage of a non-orthogonal Euclidean metric the
two-point Green's function at x = 0 for a self-interacting scalar field is
calculated. In contrast to the Minkowski space the one loop mass correction
derived from this function gives a convergent result due to an intrinsic
regularization parameter called effective dimension. This parameter is an
entropy related measure for the information loss caused by quantum fluctuations
of the metric at energies higher than the Planckian limit.",0612125v1
2007-04-24,Tachyons and superluminal boosts,"Some arguments in favour of the existence of tachyons and extensions of the
Lorentz Group are presented. On the former, it is observed that with a slight
modification to standard electromagnetic theory a single superluminal charge
will bind to itself in a self-sustaining circular orbit, suggestive of a
(modified) electromagnetic interpretation of the strong force. Symmetries in
that theory are used in the subsequent analysis as a starting point in the
search for physically-motivated extensions of the Lorentz Group. There is some
discussion of the validity of imaginary coordinates in superluminal
transformations of frame. The article concludes with some speculation on the
implications for faster-than light travel.",0704.3277v1
2007-05-18,Two field BPS solutions for generalized Lorentz breaking models,"In this work we present nonlinear models in two-dimensional space-time of two
interacting scalar fields in the Lorentz and CPT violating scenarios. We
discuss the soliton solutions for these models as well as the question of
stability for them. This is done by generalizing a model recently published by
Barreto and collaborators and also by getting new solutions for the model
introduced by them.",0705.2755v1
2007-05-22,Chiral Anomaly Beyond Lorentz Invariance,"The chiral anomaly in the context of an extended standard model with minimal
Lorentz invariance violation is studied. Taking into account bounds from
measurements of the speed of light, we argue that the chiral anomaly and its
consequences are general results valid even beyond the relativistic symmetry.",0705.3263v3
2007-06-07,Relativistic wave equation for one spin-1/2 and one spin-0 particle,"A new approach to the two-body problem based on the extension of the
$SL(2,C)$ group to the $Sp(4,C)$ one is developed. The wave equation with the
Lorentz-scalar and Lorentz-vector potential interactions for the system of one
spin-1/2 and one spin-0 particle with unequal masses is constructed.",0706.1010v1
2007-06-17,Lorentz shear modulus of a two-dimensional electron gas at high magnetic field,"We show that the Lorentz shear modulus -- one of the three elastic moduli of
a homogeneous electron gas in a magnetic field -- can be calculated exactly in
the limit of high magnetic field (i.e. in the lowest Landau level). Its value
is $\pm \hbar n/4$, where $n$ is the two-dimensional electron density and the
sign is determined by the orientation of the magnetic field. We use this result
to refine our previous calculations of the dispersion of the collective modes
of fractional quantum Hall liquids.",0706.2454v1
2007-06-26,Dirac neutrino mass from the beta decay end-point modified by the dynamics of a Lorentz-violating equation of motion,"Using a generalized procedure for obtaining the equation of motion of a
propagating fermionic particle, we examine previous claims for a lightlike
preferred axis embedded in the framework of Lorentz-invariance violation with
preserved algebra. In a high energy scale, the corresponding equation of motion
is reduced to a conserving lepton number chiral (VSR) equation, and in a low
energy scale, the Dirac equation for a free is recovered. The new dynamics
introduces some novel ingredients (modified cross section) to the phenomenology
of the tritium beta decay end-point.",0706.3932v2
2007-07-17,Renormalization of Lorentz violating theories,"We classify the unitary, renormalizable, Lorentz violating quantum field
theories of interacting scalars and fermions, obtained improving the behavior
of Feynman diagrams by means of higher space derivatives. Higher time
derivatives are not generated by renormalization. Renormalizability is ensured
by a ""weighted power counting"" criterion. The theories contain a dimensionful
parameter, yet a set of models are classically invariant under a weighted scale
transformation, which is anomalous at the quantum level. Formulas for the
weighted trace anomaly are derived. The renormalization-group properties are
studied.",0707.2480v2
2007-08-24,Lorentz violation and the proper-time method,"In this paper, we apply the proper-time method to generate the
Lorentz-violating Chern-Simons terms in the four-dimensional Yang-Mills and
non-linearized gravity theories. It is shown that the coefficient of the
induced Chern-Simons term is finite but regularization dependent.",0708.3348v1
2007-08-27,Chiral symmetry breaking and the Lorentz nature of confinement,"We address the question of the Lorentz nature of the effective interquark
interaction in QCD which leads to the formation of the QCD string between
colour charges. In particular, we start from a manifestly vectorial fundamental
interaction mediated by gluons and demonstrate that, as soon as chiral symmetry
is broken spontaneously, the effective interquark interaction acquires a
selfconsistently generated scalar part which is eventually responsible for the
formation of the QCD string. We demonstrate this explicitly for a heavy-light
quarkonium, using the approach of the Schwinger-Dyson-type equation and the
quantum-mechanical Hamiltonian method of the QCD string with quarks at the
ends.",0708.3603v1
2007-08-29,Non-commutative phase space and its space-time symmetry,"First a description of 2+1 dimensional non-commutative(NC) phase space is
presented, where the deformation of the planck constant is given. We find that
in this new formulation, generalized Bopp's shift has a symmetric
representation and one can easily and straightforwardly define the star product
on NC phase space. Then we define non-commutative Lorentz transformations both
on NC space and NC phase space. We also discuss the Poincare symmetry. Finally
we point out that our NC phase space formulation and the NC Lorentz
transformations can be applicable to any even dimensional NC space and NC phase
space.",0708.3954v1
2007-10-03,The First Lunar Ranging Constraints on Gravity Sector SME Parameters,"We present the first constraints on pure-gravity sector Standard-Model
Extension (SME) parameters using Lunar Laser Ranging (LLR). LLR measures the
round trip travel time of light between the Earth and the Moon. With 34+ years
of LLR data, we have constrained six independent linear combinations of SME
parameters at the level of $10^{-6}$ to $10^{-11}$. There is no evidence for
Lorentz violation in the LLR dataset.",0710.0701v1
2007-10-03,The Boltzmann-Grad limit of the periodic Lorentz gas in two space dimensions,"The periodic Lorentz gas is the dynamical system corresponding to the free
motion of a point particle in a periodic system of fixed spherical obstacles of
radius $r$ centered at the integer points, assuming all collisions of the
particle with the obstacles to be elastic. In this Note, we study this motion
on time intervals of order $1/r$ and in the limit as $r\to 0^+$, in the case of
two space dimensions.",0710.0716v2
2007-10-04,Time dilation of a bound half-fluxon pair in a long Josephson junction with a ferromagnetic insulator,"The fluxon dynamics in a long Josephson junction with a ferromagnetic
insulating layer is investigated. It is found that the Josephson phase obeys a
double sine-Gordon equation involving a bound pi fluxon solution, and the
internal oscillations of the bound pair acting as a clock exhibit Lorentz
reductions in their frequencies regarded as a relativistic effect in the time
domain, i.e., time dilation. This is the complement to the Lorentz contraction
of fluxons with no clock. A possible observation scheme is also discussed.",0710.0947v1
2007-10-17,Energy-dependent Lorentz covariant parameterization of the NN interaction between 50 and 200 MeV,"For laboratory kinetic energies between 50 and 200 MeV, we focus on
generating an energy-dependent Lorentz covariant parameterization of the
on-shell nucleon-nucleon (NN) scattering amplitudes in terms of a number of
Yukawa-type meson exchanges in first-order Born approximation. This
parameterization provides a good description of NN scattering observables in
the energy range of interest, and can also be extrapolated to energies between
40 and 300 MeV.",0710.3201v2
2007-11-12,Random walk approach to the d-dimensional disordered Lorentz gas,"A correlated random walk approach to diffusion is applied to the disordered
nonoverlapping Lorentz gas. By invoking the Lu-Torquato theory for chord-length
distributions in random media [J. Chem. Phys. 98, 6472 (1993)], an analytic
expression for the diffusion constant in arbitrary number of dimensions d is
obtained. The result corresponds to an Enskog-like correction to the Boltzmann
prediction, being exact in the dilute limit, and better or nearly exact in
comparison to renormalized kinetic theory predictions for all allowed densities
in d=2,3. Extensive numerical simulations were also performed to elucidate the
role of the approximations involved.",0711.1875v2
2007-11-29,A mapping between Lorentz-violating and conventional electrodynamics,"The Chern-Simons-type term in the photon sector of the Lorentz- and
CPT-breaking minimal Standard-Model Extension (mSME) is considered. It is
argued that under certain circumstances this term can be removed from the mSME.
In particular, it is demonstrated that for lightlike Lorentz violation a field
redefinition exists that maps the on-shell free Chern-Simons model to
conventional on-shell free electrodynamics. A compact explicit expression for
an operator implementing such a mapping is constructed. This expression
establishes that the field redefinition is non-local.",0711.4851v2
2007-12-04,"Lorentz transformation, time dilation, length contraction and Doppler Effect - all at once","We present a simple derivation of the Lorentz transformations for the
space-time coordinates of the same event. It is based on the relative character
of length and time interval as measured by observes in relative motion. We
begin by accepting that the relative motion modifies in some particular way the
result of these measurements. However we do not postulate the character of this
distortion i.e. whatever it is dilation or contraction. The formulas accounting
for length contraction, time dilation and Doppler shift are a byproduct of this
derivation.",0712.0463v1
2007-12-17,Erratum (astro-ph/0510172): Robust Limits on Lorentz Violation from Gamma-Ray Bursts,"We correct the fitting formula used in refs. [1,2] to obtain a robust limit
on a violation of Lorentz invariance that depends linearly on the photon
energy. The correction leads to a slight increase of the limit on the scale of
the violation, to M > 1.4 x 10^{16} GeV.",0712.2781v1
2007-12-20,Chiral tensor fields and spontaneous breaking of Lorentz symmetry,"Antisymmetric tensor fields interacting with quarks and leptons have been
proposed as a possible solution to the gauge hierarchy problem. We compute the
one-loop beta function for a quartic self-interaction of the chiral
antisymmetric tensor fields. Fluctuations of the top quark drive the
corresponding running coupling to a negative value as the renormalization scale
is lowered. This may indicate a non-vanishing expectation value of the tensor
field, and thus a spontaneous breaking of Lorentz invariance. Settling this
issue will need the inclusion of tensor loops.",0712.3405v1
2007-12-25,Twisted Quantum Deformations of Lorentz and Poincaré algebras,"We discussed twisted quantum deformations of D=4 Lorentz and Poincare
algebras. In the case of Poincare algebra it is shown that almost all classical
r-matrices of S.Zakrzewski classification can be presented as a sum of
subordinated r-matrices of Abelian and Jordanian types. Corresponding twists
describing quantum deformations are obtained in explicit form. This work is an
extended version of the paper \url{arXiv:0704.0081v1 [math.QA]}.",0712.3962v1
2007-12-28,Constraints on Torsion from Lorentz Violation,"Exceptional sensitivity to spacetime torsion can be achieved by searching for
its couplings to fermions. Recent experimental searches for Lorentz violation
are exploited to extract new constraints involving 19 of the 24 independent
torsion components down to levels of order 10^{-31} GeV.",0712.4393v2
2008-01-10,A Lorentz Invariant Pairing Mechanism: Relativistic Cooper Pairs,"We study a Lorentz invariant pairing mechanism that arises when two
relativistic spin-1/2 fermions are subjected to a Dirac string coupling. In the
weak coupling regime, we find remarkable analogies between this relativistic
bound system and the well known superconducting Cooper pair. As the coupling
strength is raised, quenched phonons become unfrozen and dynamically contribute
to the gluing mechanism, which translates into novel features of this
relativistic superconducting pair.",0801.1615v1
2008-01-18,A Lorentz Invariant Phenomenological Model of Quantum Gravity,"We consider a model of Quantum Gravity phenomenology, based on the idea that
space-time may have some unknown granular structure that respects the Lorentz
symmetry. The proposal involves non-trivial couplings of curvature to matter
fields and leads to a well defined phenomenology. In this manuscript, a brief
description of the model is presented together with some results obtained using
linearized gravity and the Newtonian limit, which could be useful when
comparing with real experiments.",0801.2919v1
2008-01-21,A Note on Spontaneously Broken Lorentz Invariance,"We consider a relativistic effective field theory of vector boson whose
vacuum exhibits spontaneous breaking of Lorentz invariance. We argue that a
simple model of this type, considered recently by Kraus and Tomboulis, is
obstructed from having a consistent ultraviolet completion according to the
diagnostic recently suggested by Adams, Arkani-Hamed, Dubovsky, Nicolis, and
Rattazzi.",0801.3266v3
2008-01-28,Lorentz Gauge Theory and Spinor Interaction,"A gauge theory of the Lorentz group, based on the different behavior of
spinors and vectors under local transformations, is formulated in a flat
space-time and the role of the torsion field within the generalization to
curved space-time is briefly discussed. The spinor interaction with the new
gauge field is then analyzed assuming the time gauge and stationary solutions,
in the non-relativistic limit, are treated to generalize the Pauli equation.",0801.4242v3
2008-02-18,On relativistic elements of reality,"Several arguments have been proposed some years ago, attempting to prove the
impossibility of defining Lorentz-invariant elements of reality. I find that a
sufficient condition for the existence of elements of reality, introduced in
these proofs, seems to be used also as a necessary condition. I argue that
Lorentz-invariant elements of reality can be defined but, as Vaidman pointed
out, they won't satisfy the so-called product rule. In so doing I obtain
algebraic constraints on elements of reality associated with a maximal set of
commuting Hermitian operators.",0802.2537v2
2008-02-22,"Spatially-separated synchronised clocks in the same inertial frame: Time dilatation, but no relativity of simultaneity or length contraction","The Lorentz transformation is used to analyse space and time coordinates
corresponding to two spatially-separated clocks in the same inertial frame. The
time dilatation effect is confirmed, but not `relativity of simultaneity' or
`relativistic length contraction'. How these latter, spurious, effects arise
from misuse of the Lorentz transformation is also explained.",0802.3298v2
2008-03-09,Explicit exact expression for the Thomas precession,"This work gives an explicit exact expression for the Thomas precession
arising in the framework of Special Theory of Relativity as the spatial
rotation resulting from two subsequence Lorentz boosts. The final result for
the orthogonal matrix of Thomas precession is given by Eqs. (21)--(25). A
trivial calculation leads to the compact formula (26) for the angle of rotation
due to Thomas precession.
  In the framework of Gaia the special-relativistic Thomas precession is an
important step in the derivation of an aberrational formula with the
Mansouri-Sexl parameters. The latter formula will be used to test the Local
Lorentz Invariance with Gaia data as will be explained elsewhere.",0803.1303v2
2008-04-23,Lorentz invariant photon number density,"A Lorentz invariant positive definite expression for photon number density is
derived as the absolute square of the invariant scalar product of a
polarization sensitive position eigenvector and the photon wave function. It is
found that this scalar product is independent of the form chosen for the wave
function and that the normalized positive frequency vector potential-electric
field pair is a convenient choice of wave function in the presence of matter.
The number amplitude describing a localized state is a delta-function at the
instant at which localization and detection are seen as simultaneous.",0804.3773v3
2008-05-09,Testing Lorentz Violation Using Propagating UHECRs,"Lorentz invariant violation (LIV) test is very important to study in the new
physics. All the known astrophysical constraints either have a very small
examinable parameter space, or are only suitable for some special theoretical
models. Here we suggest that it is possible to detect the time-delay of
ultra-high-energy cosmic-rays (UHECRs) directly. We discuss some difficulties
in our method, including the intergalactic magnetic fields. It seems that none
of them are crucial, hence this method could give a larger examinable parameter
space and a stronger constraint on LIV.",0805.1275v2
2008-05-13,Lorentz Symmetry Violation and Galactic Magnetism,"We analyze the generation of primordial magnetic fields during de Sitter
inflation in a Lorentz-violating theory of Electrodynamics containing a
Chern-Simons term which couples the photon to an external four-vector. We find
that, for appropriate magnitude of the four-vector, the generated field is
maximally helical and, through an inverse cascade caused by turbulence of
primeval plasma, reaches at the time of protogalactic collapse an intensity and
correlation length such as to directly explain galactic magnetism.",0805.1851v2
2008-05-14,Causality as an emergent macroscopic phenomenon: The Lee-Wick O(N) model,"In quantum mechanics the deterministic property of classical physics is an
emergent phenomenon appropriate only on macroscopic scales. Lee and Wick
introduced Lorentz invariant quantum theories where causality is an emergent
phenomenon appropriate for macroscopic time scales. In this paper we analyze a
Lee-Wick version of the O(N) model. We argue that in the large N limit this
theory has a unitary and Lorentz invariant S matrix and is therefore free of
paradoxes in scattering experiments. We discuss some of its acausal properties.",0805.2156v1
2008-05-17,"The Space-Cone Gauge, Lorentz Invariance and On-Shell Recursion for One-Loop Yang-Mills amplitudes","Recursion relations are succinctly obtained for $(++... +)$ and $(-++... +)$
amplitudes in the context of the space-cone gauge in QCD. We rely on the
helicity symmetry of the problems to dictate our choices of reference twistors
and the momentum shifts to complexify the amplitudes. Of great importance is
the power of gauge Lorentz invariance, which is enough to determine the soft
factors in the latter cases.",0805.2645v1
2008-05-28,On the ambiguities in the effective action in Lorentz-violating gravity,"We investigate the occurrence of ambiguities for Lorentz-violating
gravitational Chern-Simons term. It turns out that this term is accompanied by
a coefficient depending on an undetermined parameter, due to an arbitrariness
in the choice of the conserved current.",0805.4409v2
2008-06-06,The Theory of Relativity - Galileo's Child,"We determine the Lorentz transformations and the kinematic content and
dynamical framework of special relativity as purely an extension of Galileo's
thoughts. No reference to light is ever required: The theories of relativity
are logically independent of any properties of light. The thoughts of Galileo
are fully realized in a system of Lorentz transformations with a parameter
1/c^2, some undetermined, universal constant of nature; and are realizable in
no other. Isotropy of space plays a deep and pivotal role in all of this, since
here three-dimensional space appears at first blush, and persists until the
conclusion: Relativity can never correctly be fully developed in just one
spatial dimension.",0806.1234v1
2008-06-25,Finite energy scattering for the Lorentz-Maxwell equation,"In the case where the charge of the particle is small compared to its mass,
we describe the asymptotics of the Lorentz-Maxwell equation for any
finite-energy data. As time goes to infinity, we prove that the speed of the
particle converges to a certain limit, whereas the electromagnetic field can be
decomposed into a soliton plus a free solution of the Maxwell equation. It is
the first instance of a scattering result for general finite energy data in a
field-particle equation.",0806.4153v1
2008-08-11,Boundary states and edge currents for free fermions,"We calculate the ground state current densities for 2+1 dimensional free
fermion theories with local, translationally invariant boundary states.
Deformations of the bulk wave functions close to the edge and boundary states
both may cause edge current divergencies, which have to cancel in realistic
systems. This yields restrictions on the parameters of quantum field theories
which can arise as low energy limits of solid state systems. Some degree of
Lorentz invariance for boosts parallel to the boundary can be recovered, when
the cutoff is removed.",0808.1497v2
2008-08-23,Spontaneous Breaking of Lorentz-Invariance and Gravitons as Goldstone Particles,"We consider some aspects of spontaneous breaking of Lorentz Invariance in
field theories, discussing the possibility that the certain tensor operators
may condensate in the ground state in which case the tensor Goldstone particles
would appear. We analyze their dynamics and discuss to which extent such a
theory could imitate the gravity. We are also interested if the universality of
coupling of such `gravitons' with other particles can be achieved in the
infrared limit. Then we address the more complicated models when such tensor
Goldstones coexist with the usual geometrical gravitons. At the end we examine
the properties of possible cosmological scenarios in the case of goldstone
gravity coexisting with geometrical gravity.",0808.3181v1
2008-08-24,Spontaneous Broken Local Conformal Symmetry and Dark Energy Candidate,"The local conformal symmetry is spontaneously broken down to the Local
Lorentz invariance symmetry through the approach of nonlinear realization. The
resulting effective Lagrangian, in the unitary gauge, describes a cosmological
vector field non-minimally coupling to the gravitational field. As a result of
the Higgs mechanism, the vector field absorbs the dilaton and becomes massive,
but with an independent energy scale. The Proca type vector field can be
modelled as dark energy candidate. The possibility that it further triggers
Lorentz symmetry violation is also pointed out.",0808.3277v2
2008-08-26,Weighted power counting and Lorentz violating gauge theories. II: Classification,"We classify the local, polynomial, unitary gauge theories that violate
Lorentz symmetry explicitly at high energies and are renormalizable by weighted
power counting. We study the structure of such theories and prove that
renormalization does not generate higher time derivatives. We work out the
conditions to renormalize vertices that are usually non-renormalizable, such as
the two scalar-two fermion interactions and the four fermion interactions. A
number of four dimensional examples are presented.",0808.3474v2
2008-09-09,Dynamical Lorentz symmetry breaking in 3D and charge fractionalization,"We analyze the breaking of Lorentz invariance in a 3D model of fermion fields
self-coupled through four-fermion interactions. The low-energy limit of the
theory contains various sub-models which are similar to those used in the study
of the graphene or in the description of irrational charge fractionalization.",0809.1627v2
2008-09-21,The Principle of Relativity and Special Relativity Triple,"Based on the principle of relativity and the postulate on universal invariant
constants ($c,l$) as well as Einstein's isotropy conditions, three kinds of
special relativity form a triple with a common Lorentz group as isotropy group
under full Umov-Weyl-Fock-Lorentz transformations among inertial motions.",0809.3562v2
2008-09-22,Aspects of Infrared Modifications of Gravity,"In the first part of the thesis, and after an introduction to certain models
of modified gravity, we study consistent Lagrangians for Lorentz invariant
(massive and massless) spin-2 and spin-3/2 particles in flat space. The second
part of the dissertation is devoted to non-linear extensions for the spin-2
case, focusing on unimodular gravity and bigravity. Both theories lead to
modifications of General Relativity at large distances and we will study exact
solutions, causal structure of those solutions, and perturbation theory
(specially for the Lorentz breaking case). Some comments on quantization of
these theories can be found in an appendix.",0809.3744v1
2008-09-24,Space-time attributes of physical objects and the laws of space-time physics,"Physical time intervals are attributes of single physical object whereas
physical space intervals are a relational attribute of two physical objects.
Some consequences of the breaking of the space-time exchange symmetry inherent
in the Lorentz transformation following from the above distinction are
investigated. In particular, it is shown that the relativity of simultaneity
and length contraction effects which naively follow from space-time symmetry of
the Lorentz transformation do not occur. Seven laws describing the relation
between observations of space intervals, time intervals and velocities in
different reference frames are given. Only two of these laws are respected by
conventional special relativity theory.",0809.4121v1
2008-09-29,Unitary Representations of the inhomogeneous Lorentz Group and their Significance in Quantum Physics,"In honor of Minkowski's great contribution to Special Relativity, celebrated
at this conference, we first review Wigner's theory of the projective
irreducible representations of the inhomogeneous Lorentz group. We also sketch
those parts of Mackey's mathematical theory on induced representations which
are particularly useful for physicists. As an important application of the
Wigner-Mackey theory, we shall describe in a unified manner free classical and
quantum fields for arbitrary spin, and demonstrate that locality implies the
normal spin-statistics connection.",0809.4942v1
2008-10-08,New indirect bounds on Lorentz violation in the photon sector,"Direct laboratory bounds on the 9 nonbirefringent Lorentz-violating
dimensionless parameters of modified-Maxwell theory range from the 10^{-7}
level to the 10^{-16} level. The detection of air showers initiated by charged
primaries (ultrahigh-energy cosmic-rays) and neutral primaries (TeV gamma-rays)
allows us to obtain new indirect bounds ranging from the 10^{-15} level to the
10^{-19} level. Possible physics implications are briefly discussed.",0810.1446v3
2008-10-18,Differential Geometry of Curves and Surfaces in Lorentz-Minkowski space,"We review part of the classical theory of curves and surfaces in
$3$-dimensional Lorentz-Minkowski space. We focus in spacelike surfaces with
constant mean curvature pointing the differences and similarities with the
Euclidean space.",0810.3351v2
2008-10-23,A simple derivation of the electromagnetic field of an arbitrarily moving charge,"The expression for the electromagnetic field of a charge moving along an
arbitrary trajectory is obtained in a direct, elegant, and Lorentz invariant
manner without resorting to more complicated procedures such as differentiation
of the Lienard-Wiechert potentials. The derivation uses arguments based on
Lorentz invariance and a physically transparent expression originally due to
J.J.Thomson for the field of a charge that experiences an impulsive
acceleration.",0810.4246v1
2008-10-29,Lorentz invariance relations between parton distributions and the Wandzura-Wilczek approximation,"The violation of the so-called Lorentz invariance relations between parton
distribution functions is considered in a model independent way. It is shown
that these relations are not violated in a generalized Wandzura-Wilczek
approximation, indicating that numerically their violation may be small.",0810.5212v3
2008-11-06,Synchrony parameter dependent transformation equations and some of their particular values - Kinematics,"We show that alternative relativity theories that are essentially based on
varied distant clock synchronization procedures can be recovered by using the
standard Lorentz-Einstein transformations for the space-time coordinates of the
same event. Through this approach we offer modest support for the Rizzi et al.
stating that: ""Once correctly and explicitly phrased, the principles of special
relativity theory allow for a wide range of theories that differ from the
standard Einstein's theory only for the difference in the chosen
synchronization procedure, but are wholly equivalent to special relativity
theory in predicting empirical facts."" Our approach requires of the reader no
more then a correct understanding of the physics behind the Lorentz-Einstein
transformations equations which we use.",0811.0957v1
2008-12-02,Non-relativistic holography,"We consider holography for d-dimensional scale invariant but non-Lorentz
invariant field theories, which do not admit the full Schrodinger symmetry
group. We find new realizations of the corresponding (d+1)-dimensional gravity
duals, engineered with a variety of matter Lagrangians, and their finite
temperature generalizations. The thermodynamic properties of the finite
temperature backgrounds are precisely those expected for anisotropic, scale
invariant field theories. The brane and string theory realizations of such
backgrounds are briefly discussed, along with their holographic interpretation
in terms of marginal but non Lorentz invariant deformations of conformal field
theories. We initiate discussion of holographic renormalization in these
backgrounds, and note that such systematic renormalization is necessary to
obtain the correct behavior of correlation functions.",0812.0530v1
2008-12-19,Maxwell-Kostelecký Electromagnetism and Cosmic Magnetization,"The Lorentz violating term in the photon sector of Standard Model Extension,
$\mathcal{L}_K = -{$\frac14$} (k_F)_{\alpha \beta \mu \nu} F^{\alpha \beta}
F^{\mu \nu}$ (here referred to as the Kosteleck\'{y} term), breaks conformal
invariance of electromagnetism and enables a superadiabatic amplification of
magnetic vacuum fluctuations during inflation. For a wide range of values of
parameters defining Lorentz symmetry violation and inflation, the present-day
magnetic field can have an intensity of order of nanogauss on megaparsec scales
and then could explain the large-scale magnetization of the universe.",0812.3745v2
2008-12-29,On Galilean and Lorentz invariance in pilot-wave dynamics,"It is argued that the natural kinematics of the pilot-wave theory is
Aristotelian. Despite appearances, Galilean invariance is not a fundamental
symmetry of the low-energy theory. Instead, it is a fictitious symmetry that
has been artificially imposed. It is concluded that the search for a
Lorentz-invariant extension is physically misguided.",0812.4941v1
2009-01-20,Electromagnetic Force as consequence of the Geometry of Minkowskian Spacetime,"By describing the dynamical evolution of a test charged particle in the
presence of an electromagnetic field as a succession of infinitesimal Lorentz
boosts and rotations it is possible to obtain the Lorentz Force of
Electrodynamics. A consequence of this derivation at the classical level is
that, given the existence of electric and magnetic fields, the form of the
electromagnetic force acting on the particle can be regarded as arising from
the geometry of Minkowskian spacetime.",0901.2999v1
2009-02-06,On the ill-posed character of the Lorentz integral transform,"An exact inversion formula for the Lorentz integral transform (LIT) is
provided together with the spectrum of the LIT kernel. The exponential increase
of the inverse Fourier transform of the LIT kernel entering the inversion
formula explains the ill-posed character of the LIT approach. Also the
continuous spectrum of the LIT kernel, which approaches zero points necessarily
to the same defect. A possible cure is discussed and numerically illustrated.",0902.1081v1
2009-02-07,"Asymmetrically Warped Brane Models, Bulk Photons and Lorentz Invariance","We present a brief review of our recent work [1] on asymmetrically warped
brane models, where the background metric is characterized by different time
and space warp factors. In particular we examine the case of bulk photons and
we show that the standard Lorentz invariant dispersion relation is corrected by
nonlinear terms which lead to an Energy-dependent speed of light. Stringent
constraints on the parameters of our models can be set by comparing the results
with recent data from high-energy Gamma-Ray Astrophysics, for instance the
MAGIC Telescope.",0902.1243v3
2009-02-19,4d Lorentzian Holst action with topological terms,"We study the Hamiltonian formulation of the general first order action of
general relativity compatible with local Lorentz invariance and background
independence. The most general simplectic structure (compatible with
diffeomorphism invariance and local Lorentz transformations) is obtained by
adding to the Holst action the Pontriagin, Euler and Nieh-Yan invariants with
independent coupling constants. We perform a detailed canonical analysis of
this general formulation (in the time gauge) exploring the structure of the
phase space in terms of connection variables. We explain the relationship of
these topological terms, and the effect of large SU(2) gauge transformations in
quantum theories of gravity defined in terms of the Ashtekar-Barbero
connection.",0902.3416v1
2009-04-03,The Role of Time Gauge in Quantizing Gravity,"We present the Hamiltonian formulation of General Relativity with the Holst
formulation in a generic local Lorentz frame. In particular, we outline that a
Gauss constraint is inferred by a proper generalization of
Ashtekar-Barbero-Immirzi connections. This feature allow to extend the Loop
Quantum Gravity quantization procedure to the case in which no gauge fixing at
all is performed of the Lorentz frame.",0904.0573v1
2009-04-07,One-Loop Renormalization of the Electroweak Sector with Lorentz Violation,"The one-loop renormalizability of the electroweak sector of the Standard
Model Extension with Lorentz violation is studied. Functional determinants are
used to calculate the one-loop contributions of the higgs, gauge bosons and
fermions to the one-loop effective action. The results are consistent with
multiplicative renormalization of the SME coupling constants. Conventional
Electroweak symmetry breaking is effectively unaltered relative to the standard
case as the renormalized SME parameters are sufficient to absorb all infinite
contributions.",0904.1219v1
2009-05-06,Positive knots have negative signature,"It was asked by J.Birman, Williams, and L.Rudolph whether nontrivial Lorentz
knots have always positive signature. Lorentz knots are examples of positive
braids (in our convention they have all crossings negative so they are negative
links). It was shown by L.Rudolph that positive braids have positive signature
(if they represent nontrivial links). K.Murasugi has shown that nontrivial,
alternating, positive links have negative signature. Here we prove in general
the old folklore conjecture that nontrivial positive links have negative
signature.",0905.0922v1
2009-05-13,Nonorientable maximal surfaces in the Lorentz-Minkowski 3-space,"The geometry and topology of complete nonorientable maximal surfaces with
lightlike singularities in the Lorentz-Minkowski 3-space are studied. Some
topological congruence formulae for surfaces of this kind are obtained. As a
consequence, some existence and uniqueness results for maximal Moebius strips
and maximal Klein bottles with one end are proved.",0905.2113v3
2009-05-29,Comments on the Tetrad (Vielbeins),"We want to correct the misunderstandings on the tetrad (or veilbeins in
general) appeared in many text books or review articles. The tetrad should be
defined without any condition. $e_{\mu a}=\partial_\mu X_a$ with local Lorentz
coordinates $X_a$ ia wrong in many sences: it gives the condition $\partial_\mu
e_{\nu a}=\partial_\nu e_{\mu a}$, which leads us to the trivial result that
the cyclic coefficients vanish identically and to the null Riemannian tensor.
Also $e_{\mu a}e_\nu^a=g_{\mu\nu}$ is not scalar under the local Lorentz
transformation etc. We show how these deficits are remedied by the correct
definition, $e_{\mu a}=D_\mu Z_a$ with local (Anti) de Sitter coordinates
$Z_A$.",0905.4792v1
2009-06-04,Fluctuating solutions for the evolution of domain walls,"A class of oscillating Lorentz covariant configurations for the evolution of
the domain walls in diverse dimensions are analytically obtained. It is shown
that the oscillating solutions in the case of domain walls are responsible for
structures which are larger than the usual kink-like configurations and, in the
Lorentz covariant evolution case, lead to long-standing configurations.",0906.0852v1
2009-06-10,"Lorentz contraction, Bell's spaceships, and rigid body motion in special relativity","The meaning of Lorentz contraction in special relativity and its connection
with Bell's spaceships parable is discussed. The motion of Bell's spaceships is
then compared with the accelerated motion of a rigid body. We have tried to
write this in a simple form that could be used to correct students'
misconceptions due to conflicting earlier treatments.",0906.1919v3
2009-06-22,Lorentz force on an electron in a strong plane-wave laser field and the low-frequency limit for ionization,"A motion of a classical free charge in an electromagnetic plane wave can be
found exactly in a fully relativistic case. We have found an approximate
non-parameter form of the suitable equations of motion. In a linearly polarized
wave, in the simplest frame of reference, the charge moves along the well-known
""figure-8"" path. We have numerically calculated the Lorentz force acting on the
charge as a function of time. In virtue of this, for the low frequency
ionization (or detachment) rate, we discuss a manifestation of nondipole and
relativistic effects.",0906.4098v1
2009-06-26,A genetic algorithm for structure-activity relationships: software implementation,"The design and the implementation of a genetic algorithm are described. The
applicability domain is on structure-activity relationships expressed as
multiple linear regressions and predictor variables are from families of
structure-based molecular descriptors. An experiment to compare different
selection and survival strategies was designed and realized. The genetic
algorithm was run using the designed experiment on a set of 206 polychlorinated
biphenyls searching on structure-activity relationships having known the
measured octanol-water partition coefficients and a family of molecular
descriptors. The experiment shows that different selection and survival
strategies create different partitions on the entire population of all possible
genotypes.",0906.4846v1
2009-06-30,Symmetries of fundamental interactions in quantum phase space,"Quantum operators of coordinates and momentum components of a particle in
Minkowski space-time belong to a noncommutative algebra and give rise to a
quantum phase space. Under some constraints, in particular, the Lorentz
invariance condition, the algebra of observables, including Lorentz group
generators, depends on additional fundamental physical constants with the
dimensions of mass, length and action. Generalized symmetries in a quantum
phase space and some consequences for fundamental interactions of particles are
considered.",0906.5422v2
2009-06-30,CPT-violating neutrino oscillations,"We propose a simple phenomenological model predicting, through Lorentz
symmetry breaking, a CPT-violating asymmetry between particle and antiparticle
states in neutrino oscillations involving sterile neutrinos. Such a model is
able to explain the apparently observed anomalous excess of low-energy
\nu_e-like events, reported by the MiniBooNE collaboration, as well as the
non-observation of the corresponding anomalous excess of \ov{\nu}_e-like
events. The present model leads to very specific physical predictions in the
neutrino oscillations scenario, and account for the observed anomalies in terms
of only one CPT-Lorentz violation parameter of the order of the
Grand-Unification energy scale.",0906.5542v1
2009-07-08,CPT and Lorentz violation as signatures for Planck-scale physics,"In recent years, the breakdown of spacetime symmetries has been identified as
a promising research field in the context of Planck-scale phenomenology. For
example, various theoretical approaches to the quantum-gravity problem are
known to accommodate minute violations of CPT invariance. This talk covers
various topics within this research area. In particular, some mechanisms for
spacetime-symmetry breaking as well as the Standard-Model Extension (SME) test
framework will be reviewed; the connection between CPT and Lorentz invariance
in quantum field theory will be exposed; and various experimental CPT tests
with emphasis on matter--antimatter comparisons will be discussed.",0907.1319v1
2009-07-16,Probing Lorentz Invariance at EeV Energy,"Pierre Auger experiment has detected at least a couple of ray events above
energy 60 EeV from the direction of the radio-galaxy Centaurus A. Assuming
those events are from Centaurus A, we have calculated the number of neutral
cosmic ray events from this source for small values of the degree of violation
in Lorentz invariance. Our results show that a comparison of our calculated
numbers of events with the observed number of events at EeV energy from the
direction of the source can probe extremely low value of the degree of this
violation.",0907.2752v1
2009-08-03,Information and Particle Physics,"Information measures for relativistic quantum spinors are constructed to
satisfy various postulated properties such as normalisation invariance and
positivity. Those measures are then used to motivate generalised Lagrangians
meant to probe shorter distance physics within the maximum uncertainty
framework. The modified evolution equations that follow are necessarily
nonlinear and simultaneously violate Lorentz invariance, supporting previous
heuristic arguments linking quantum nonlinearity with Lorentz violation. The
nonlinear equations also break discrete symmetries. We discuss the implications
of our results for physics in the neutrino sector and cosmology.",0908.0180v2
2009-09-11,Rotating Odd-Parity Lorentz Invariance Test in Electrodynamics,"We report the first operation of a rotating odd-parity Lorentz Invariance
test in electrodynamics using a microwave Mach-Zehnder interferometer with
permeable material in one arm. The experiment sets a direct bound to $
\kappa_{tr}$ of $-0.3\pm 3\times10^{-7}$. Using new power recycled waveguide
interferometer techniques (with the highest spectral resolution ever achieved
of $2\times10^{-11} rad/\sqrt{Hz}$) we show an improvement of several orders of
magnitude is attainable in the future.",0909.2076v2
2009-09-16,Recurrence for quenched random Lorentz tubes,"We consider the billiard dynamics in a strip-like set that is tessellated by
countably many translated copies of the same polygon. A random configuration of
semidispersing scatterers is placed in each copy. The ensemble of dynamical
systems thus defined, one for each global choice of scatterers, is called
`quenched random Lorentz tube'. We prove that, under general conditions, almost
every system in the ensemble is recurrent.",0909.3069v2
2009-09-30,On Hardy inequalities with a remainder term,"In this paper we study some improvements of the classical Hardy inequality.
We add to the right hand side of the inequality a term which depends on some
Lorentz norms of $u$ or of its gradient and we find the best values of the
constants for remaining terms. In both cases we show that the problem of
finding the optimal value of the constant can be reduced to a spherically
symmetric situation. This result is new when the right hand side is a Lorentz
norm of the gradient.",0909.5690v2
2009-10-01,Lorentz Transform of Black Body Radiation Temperature,"The Lorentz transform of black body radiation has been investigated from the
view point of relativistic statistical mechanics. The result shows that the
well known expression with the directional temperature can be derived based on
the inverse temperature four vector. The directional temperature in the past
literature was the result of mathematical manipulation and its physical meaning
is not clear. The inverse temperature four vector has, in contrast, clear
meaning to understand relativistic thermodynamical processes.",0910.0164v1
2009-10-17,A UV completion of scalar field theory in arbitrary even dimensions,"Following a previous work (hep-th/0410248), where a scalar field theory with
a modified propagator and phi^4 interaction in 4 dimensions is constructed to
be UV-finite, unitary and Lorentz invariant, we discuss in this paper general
phi^n theory in arbitrary even space-time dimensions. We show that the theory
is still UV-finite, unitary and Lorentz invariant if the propagators are chosen
to meet certain simple conditions depending on the space-time dimension but
independent of n. We also comment that our model is reminiscent of string
theory in the way UV divergence is avoided.",0910.3287v1
2009-10-27,Radiatively Induced Lorentz and Gauge Symmetry Violation in Electrodynamics with Varying alpha,"A time-varying fine structure constant alpha(t) could give rise to Lorentz-
and CPT-violating changes to the vacuum polarization, which would affect photon
propagation. Such changes to the effective action can violate gauge invariance,
but they are otherwise permitted. However, in the minimal theory of varying
alpha, no such terms are generated at lowest order. At second order, vacuum
polarization can generate an instability--a Lorentz-violating analogue of a
negative photon mass squared -m^2 proportional to alpha [(d alpha/dt) /
alpha]^2 log (Lambda^2), where Lambda is the cutoff for the low-energy
effective theory.",0910.5202v1
2010-02-03,Lorentz Transformation Equations in Galilean Form,"Using the notion, developed in an earlier paper, of ""representation"" of
""position"" by a vector in a vector space with an inner product, we show that
the Lorentz Transformation Equations relating positions in two different
reference frames can be put in a particularly simple form which could be said
to be ""Galilean"". We emphasize that two different reference frames can use a
common vector space for representation but with two different inner products.
The inner products are defined through the observational set-up of each frame.",1002.0656v1
2010-02-08,Absolute motion determined from Michelson-type experiments in optical media,"The symmetry of vacuum is characterized by the Lorentz group with the
parameter $c$. Physical space inside the homogeneous optical medium should be
described by the Lorentz group with the parameter $c/n$, where $n$ is the
refractive index of the medium. Violation of a one-parameter phenomenological
symmetry in the discrete medium, such as gas, creates the opportunity for the
experimental detecting the motion of the optical medium relative to
luminiferous aether.",1002.1619v6
2010-02-13,Renormalization Of High-Energy Lorentz Violating Four Fermion Models,"We study the one-loop renormalization of high-energy Lorentz violating four
fermion models. We derive general formulas and then consider a number of
specific models. We study the conditions for asymptotic freedom and give a
practical method to determine the asymptotic-freedom domain. We also point out
that in some models the RG flow contains ""rational"" Zimmermann trajectories
that might hide new symmetries.",1002.2704v2
2010-02-15,Fermi and Swift observations of the bright short GRB 090510,"The bright short-hard GRB 090510 was observed by both Swift and Fermi
telescopes. The study of the prompt emission by Fermi revealed an additional
high-energy spectral component, the largest lower limit ever on the bulk
Lorentz factor in a short GRB jet, and brought the most stringent constraint
ever on linear Lorentz invariance violation models. The fast repoint and
follow-up by both telescopes allowed the first multiwavelength study of a GRB
afterglow from optical range to several GeV. This long-lived emission has been
studied in the framework of the internal shock and external shock models.",1002.2863v1
2010-02-19,Lorentz Transformation in Flat 5D Complex-Hyperbolic Space,"The Lorentz transfomation is derived in 5D flat pseudo-complex affine space
or TT Space. The TT space or pseudo-Complex space accomodates one
uncompactified time-like extra dimension. It is shown that the maximum
allowable speed for particles living in TT space exceeds the speed of light, c,
the absolute speed of the Minkowski space.",1002.3821v2
2010-02-24,Symmetry preserving regularization with a cutoff,"A Lorentz and gauge symmetry preserving regularization method is proposed in
4 dimension based on momentum cutoff. We use the conditions of gauge invariance
or freedom of shift of the loop-momentum to define the evaluation of the terms
carrying Lorentz indices, e.g. proportional to k_{\mu}k_{\nu}. The remaining
scalar integrals are calculated with a four dimensional momentum cutoff. The
finite terms (independent of the cutoff) are unambiguous and agree with the
result of dimensional regularization.",1002.4490v2
2010-06-25,Projective Structure and Holonomy in 4-dimensional Lorentz Manifolds,"This paper studies the situation when two 4-dimensional Lorentz manifolds
(that is, space-times) admit the same (unparametrised) geodesics, that is, when
they are projectively related. A review of some known results is given and then
the problem is considered further by treating each holonomy type in turn for
the space-time connection. It transpires that all holonomy possibilities can be
dealt with completely except the most general one and that the consequences of
two space-times being projectively related leads, in many cases, to their
associated Levi-Civita connections being identical.",1006.5023v1
2010-07-28,Gauge non-invariance as tests of emergent gauge symmetry,"We motivate the concept of emergent gauge symmetry and discuss ways that this
concept can be tested. The key idea is that if a symmetry is emergent, one
should look for small violations of this symmetry because the underlying
fundamental theory does not contain the symmetry. We describe our recent work
implementing this idea in the gravity sector. We also describe the reasons why
violations of gauge symmetry may well be linked to violations of Lorentz
invariance.",1007.5049v1
2010-08-02,Status and prospects for Lorentz and CPT violation tests at KLOE and KLOE-2,"The neutral kaon system offers a unique possibility to perform fundamental
tests of CPT invariance. In this contribution the KLOE prospects for the
measurements of CPT violation in the context of the Standard Model Extension
are presented together with a full description of the analysis method needed
and with the perspective given by the KLOE-2 data-taking campaign.",1008.0259v2
2010-08-05,Test for Lorentz and CPT Violation with the MiniBooNE Low-Energy Excess,"The MiniBooNE experiment is a $\nu_\mu\to\nu_e$ and $\bar\nu_\mu\to\bar\nu_e$
appearance neutrino oscillation experiment at Fermilab. The neutrino mode
oscillation analysis shows an excess of $\nu_e$ candidate events in the
low-energy region. These events are analyzed under the SME formalism, utilizing
the short baseline approximation. The preliminary result shows the time
independent solution is favored. The relationship with the SME parameters
extracted from the LSND experiment is discussed. The systematic error analysis
and antineutrino mode analysis are outlined.",1008.0906v1
2010-08-20,Mean spin entanglement of two massive Dirac particles under Lorentz transformations,"We have studied the relativistic effects on the mean spin entanglement of two
massive Dirac particles using the simultaneous eigen-spinors of the
Foldy-Woutheysen mean spin operator and the Dirac Hamiltonian. We have obtained
the transformation matrix from the spinor with specific momentum to the spinor
with a transformed momentum under an arbitrary Lorentz transformation. Using
the transformation matrix we have shown the consistent monotonic behavior
between the concurrence and the maximum value of Bell parameter in Bell
inequality of transformed spin states.",1008.3447v1
2010-08-30,Non-relativistic Supersymmetry,"We construct an N=1 supersymmetric gauge theory from z=3 Lifshitz field
theory. By modifying the supersymmetry (susy) algebra based on the spacetime
symmetry SO(3) $\times$ scaling symmetry, we get a supersymmetric Lagrangian
with scalar, fermion and gauge fields, all of whom have the same limiting
speed. This solves some naturalness problems of the original Lifshitz theory
which is characterized by Lorentz symmetry violation. In order that the susy
breaking does not introduce any disastrous terms into the theory, the susy
breaking scale is required to be smaller than the scale of Lorentz symmetry
violation.",1008.5102v1
2010-09-20,Operational methods and Lorentz-type equations of motion,"We propose an operational method for the solution of differential equations
involving vector products. The technique we propose is based on the use of the
evolution operator, defined in such a way that the wealth of techniques
developed within the context of quantum mechanics can also be exploited for
classical problems. We discuss the application of the method to the solution of
the Lorentz-type equations.",1009.3818v2
2010-11-08,Applications of the Lorentz-Abraham-Dirac equation in long-term dynamics,"To improve the presentation we modified the title and used the framework of
perturbation modeling of long-term dynamics so as to present the
Lorentz-Abraham-Dirac equation as the lowest order, asymptotic differential
relation for the velocity of a charged point-like mass. We formulated two
propositions and added two references.",1011.1805v3
2010-11-15,Lorentz invariance of entanglement classes in multipartite systems,"We analyze multipartite entanglement in systems of spin-1/2 particles from a
relativistic perspective. General conditions which have to be met for any
classification of multipartite entanglement to be Lorentz invariant are
derived, which contributes to a physical understanding of entanglement
classification. We show that quantum information in a relativistic setting
requires the partition of the Hilbert space into particles to be taken
seriously. Furthermore, we study exemplary cases and show how the spin and
momentum entanglement transforms relativistically in a multipartite setting.",1011.3374v2
2010-11-19,Emergent gravitational dynamics from multi-BEC hydrodynamics?,"In this paper, we examine the possibility to implement some form of emergent
Newtonian gravity in a generic multi-component Bose--Einstein condensate.
Parallely to what happens for the emergence of low energy Lorentz invariance,
strong requirements have to be imposed on the underlying condensed matter
model. We will show, within a simplified model, that the presence of a global
symmetry alleviates the problems associated to Lorentz violation, allows the
presence of a long range potential, to which the analogue matter fields (the
quasi-particles) are coupled following a weaker form of equivalence principle.",1011.4411v1
2010-12-19,4-dimensional Spin-foam Model with Quantum Lorentz Group,"We study the quantum group deformation of the Lorentzian EPRL spin-foam
model. The construction uses the harmonic analysis on the quantum Lorentz
group. We show that the quantum group spin-foam model so defined is free of the
infra-red divergence, thus gives a finite partition function on a fixed
triangulation. We expect this quantum group spin-foam model is a spin-foam
quantization of discrete gravity with a cosmological constant.",1012.4216v3
2010-12-29,Finsler metrics and CPT,"The role of Finsler-like metrics in situations where Lorentz symmetry
breaking and also CPT violation are discussed. Various physical instances of
such metrics both in quantum gravity and analogue systems are discussed. Both
differences and similarities between the cases will be emphasised. In
particular the medium of D-particles that arise in string theory will be
examined. In this case the breaking of Lorentz invariance, at the level of
quantum fluctuations, together with concomitant CPT in certain situations will
be analysed. In particular it will be shown correlations for neutral meson
pairs will be modified and a new contribution to baryogenesis will appear.",1012.5964v1
2011-01-10,Magnetic measurement of the critical current anisotropy in coated conductors,"We determine the critical current anisotropy at maximum Lorentz force from
hysteresis loops in a vibrating sample magnetometer. To eliminate the signal of
spurious variable Lorentz force currents it is sufficient to cut the sample to
a specific length, which is calculated from the position dependent sensitivity
of the instrument. The procedure increases the resolution of the measurement
and the results compare well to transport data on the same sample. As the
electric field in magnetisation measurements is lower than in transport
experiments the anisotropy at high currents (low temperatures and fields) can
be measured without the need of making current contacts or any special sample
preparation.",1101.1788v1
2011-01-24,Lorentz Symmetry Violation in Neutrinos in Curved Spacetime and its Consequences,"The neutrino propagating in curved spacetimes, e.g. around black holes, in
early curved universe, violates Lorentz and then CPT symmetry, at least in the
local coordinate. This occurs due to coupling of spin of the neutrino to
background spin connection which modifies the underlying dispersion relation.
This results in the neutrino asymmetry and hence as a consequence neutrino
oscillation probability gets affected.",1101.4628v1
2011-02-01,Cavity Bounds on Higher-Order Lorentz-Violating Coefficients,"We determine the sensitivity of a modern Michelson-Morley resonant-cavity
experiment to the higher-order nonbirefringent and nondispersive coefficients
of the Lorentz-violating Standard-Model Extension. Data from a recent year-long
run of the experiment is used to place the first bounds on these coefficients.",1102.0081v2
2011-02-01,Seven-Dimensional Super-Yang-Mills Theory in N=1 Superfields,"We give a gauge-covariant formulation of seven-dimensional super-Yang-Mills
theory in terms of N=1 superfields. Furthermore, we show that five and seven
dimensions are the only cases where such a formulation exists by analysing the
interplay of Lorentz and R symmetries. The action is expressed in terms of
field strengths and a Chern--Simons-like superpotential. Each term is
manifestly N=1 supersymmetric, Lorentz invariant in four dimensions and gauge
invariant under superfield gauge transformations, including those that do not
preserve Wess--Zumino gauge.",1102.0285v1
2011-03-14,Properties of a consistent Lorentz-violating Abelian gauge theory,"A Lorentz violating modification of massless QED is proposed, with higher
order space derivatives for the photon field. The fermion dynamical mass
generation is studied with the Schwinger-Dyson approach. Perturbative
properties of the model are calculated at one-loop and discussed at
higher-order loops, showing the consistency of the model. We explain that there
is no contradiction with the definition of the speed of light c, although
fermions see an an effective light cone, with a maximum speed smaller than c.",1103.2701v3
2011-04-28,Riemann-Finsler geometry and Lorentz-violating kinematics,"Effective field theories with explicit Lorentz violation are intimately
linked to Riemann-Finsler geometry. The quadratic single-fermion restriction of
the Standard-Model Extension provides a rich source of pseudo-Riemann-Finsler
spacetimes and Riemann-Finsler spaces. An example is presented that is
constructed from a 1-form coefficient and has Finsler structure complementary
to the Randers structure.",1104.5488v1
2011-05-06,An Analogy of the Quantum Hall Condutivity in a Lorentz-symmetry Violation Setup,"We investigated some influences of unconventional physics, such
Lorentz-symmetry violation, for quantum mechanical systems. In this context, we
calculated a important contribution for Standard Model Extension. In the
non-relativistic limit, we obtained a analogy of the Landau levels and the
quantum Hall conductivity related to this contribution for low energy systems.",1105.1401v2
2011-05-07,Lorentz Transform and Staggered Finite Differences for Advective Acoustics,"We study acoustic wave propagation in a uniform stationary flow. We develop a
method founded on the Lorentz transform and a hypothesis of irrotationality of
the acoustic perturbation. After a transformation of the space-time and of the
unknown fields, we derive a system of partial differential equations that
eliminates the external flow and deals with the classical case of non advective
acoustics. A sequel of the analysis is a new set of perfectly matched layers
equations in the spirit of the work of Berenger and Collino. The numerical
implementation of the previous ideas is presented with the finite differences
method HaWAY on cartesian staggered grids. Relevant numerical tests are
proposed.",1105.1458v1
2011-06-17,Is Eternal Inflation Eternal?,"In this paper we explore the relationship between the existence of eternal
inflation and the initial conditions leading to inflation. We demonstrate that
past and future completion of inflation is related, in that past-incomplete
inflation can not be future eternal. Bubble universes nucleating close to the
initial conditions hypersurface have the largest Lorentz boosts and experience
the highest anisotropy. Consequently, their probability to collide upon
formation is one. Thus instead of continuing eternally inflation ends soon
after it starts. The difficulty in actualizing eternal inflation originates
from the breaking of two underlying symmetries: Lorentz invariance and the
general covariance of the theory which lead to an inconsistency of Einstein
equations. Eternal inflation may not be eternal.",1106.3542v1
2011-06-24,The thermal conductance of a two-channel Kondo model,"A theory of thermal transport in a two-channel Kondo system, such as the one
formed by a small quantum dot coupled to two leads and to a larger dot, is
formulated. The interplay of the two screening constants allows an exploration
of the Fermi liquid and non-Fermi liquid regimes. By using analytical, as well
as numerical renormalization group methods, we study the temperature dependence
of the thermal conductance and the Lorentz number. We find that in the low
temperature limit, the Lorentz number attains its universal value, irrespective
of the nature of the ground state.",1106.4900v1
2011-06-24,Distribution fitting 12. Sampling distribution of compounds abundance from plant species measured by instrumentation. Application to plants metabolism classification,"A series of ten plant species belonging to Magnoliopsida - Dicotyledons class
were analyzed in terms of chemical compounds distribution of abundance,
starting from the assumption that these distributions should give a picture of
similarities and differences between plants metabolism. From a pool of
theoretical distributions, log-normal distribution was selected giving the best
accuracy with the modeled phenomena and agreement with the observed data. From
obtained lognormal distributions statistics a classification were constructed
and were compared with the classification based on phylogeny.",1106.4954v2
2011-06-28,Electromagnetic Mach principle,"We will introduce a gauge model which an electromagnetic coupling constant
and local mass are related to all the charge in the universe. we will use the
standard Dirac action, but where the mass and the electromagnetic coupling
constant are a function of the sum of all the charge in the universe, which
represent Mach principle for electromagnetic coupling constant. The
formalisation is not manifestly Lorentz invariant, however Lorentz invariance
can be restored by performing a phase transformation of the Dirac field.",1106.5661v1
2011-07-12,Photon Scattering with the Lorentz Integral Transform Method,"The application of the Lorentz integral transform (LIT) method to photon
scattering off nuclei is presented in general. As an example, elastic photon
scattering off the deuteron in the unretarded dipole approximation is
considered using the LIT method. The inversion of the integral transform is
discussed in detail paying particular attention to the high-energy
contributions in the resonance term. The obtained E1-polarizabilities are
compared to results from the literature. The corresponding theoretical cross
section is confronted with experimental results confirming, as already known
from previous studies, that the E1-contribution is the most important one at
lower energies.",1107.2320v1
2011-07-29,Chlorophylls - natural solar cells,"A molecular modeling study was conducted on a series of six natural occurring
chlorophylls. Quantum chemistry calculated orbital energies were used to
estimate frequency of transitions between occupied molecular orbital and
unoccupied molecular orbital energy levels of chlorophyll molecules in vivo
conditions in standard (ASTMG173) environmental conditions. Obtained results
are in good agreement with energies necessary to fix the Magnesium atom by
chlorophyll molecules and with occurrence of chlorophylls in living vegetal
organisms.",1107.5880v1
2011-08-14,Spontaneous Breaking of Lorentz Symmetry by Ghost Condensation in Perturbative Quantum Gravity,"In this paper we will study the spontaneous breakdown of the Lorentz symmetry
by ghost condensation in perturbative quantum gravity. Our analysis will be
done in the Curci-Ferrari gauge. We will also analyse modification of the BRST
and the anti-BRST transformations by the formation of this ghost condensate. It
will be shown that even though the modified BRST and the modified anti-BRST
transformations are not nilpotent, their nilpotency is restored on-shell.",1108.2853v2
2011-08-26,Kinetics of a frictional granular motor,"Within the framework of a Boltzmann-Lorentz equation, we analyze the dynamics
of a granular rotor immersed in a bath of thermalized particles in the presence
of a frictional torque on the axis. In numerical simulations of the equation,
we observe two scaling regimes at low and high bath temperatures. In the large
friction limit, we obtain the exact solution of a model corresponding to
asymptotic behavior of the Boltzmann-Lorentz equation. In the limit of large
rotor mass and small friction, we derive a Fokker-Planck equation for which the
exact solution is also obtained.",1108.5311v1
2011-09-14,Why is the magnetic force similar to a Coriolis force?,"It is pointed out that the underlying reason why the magnetic force is
similar to a Coriolis force is that it is caused by Thomas rotations, induced
by successions of non-collinear Lorentz boosts. The magnetic force may even be
viewed as a kind of Coriolis force (making perhaps more acceptable the apparent
non-existence of magnetic monopoles). We also show that under a change of
inertial frames, Faraday lines of force Lorentz contract as if 'etched' in
space, while 'Coriolis' terms get added on.",1109.3624v1
2011-09-20,Isometric embedding of negatively curved complete surfaces in Lorentz-Minkowski space,"Hilbert-Efimov theorem states that any complete surface with curvature
bounded above by a negative constant can not be isometrically imbedded in
$\mathbb{R}^3.$ We demonstrate that any simply-connected smooth complete
surface with curvature bounded above by a negative constant admits a smooth
isometric embedding into the Lorentz-Minkowski space $\mathbb{R}^{2,1}$.",1109.4211v2
2011-09-24,Neutrinos superluminality and Local Lorentz Invariance,"The recent measurement of the neutrino velocity with the OPERA detector in
the CNGS beam, on whose basis it was found that (v-c)/c = (2.48 \pm 0.28
(stat.) \pm 0.30 (sys.)) 10e-5, does not contain any significant violation of
Local Lorentz Invariance (LLI), since the corresponding value of the parameter
delta=(u/c)^2-1, that represents the upper limit of the breakdown of LLI, is at
least three orders of magnitude higher than the known lower limit reported in
literature and is compatible with the values estimated by other experiments
carried out so far.",1109.5289v3
2011-09-27,Mass-dependent Lorentz Violation and Neutrino Velocity,"Motivated by a recent and several earlier measurement results of the neutrino
velocity, we attempt to resolve the apparent discrepancies between them from
the viewpoint of mass-energy relation in special relativity. It is argued that
a complicated tachyonic neutrino model or a mass-dependent Lorentz violation
theory can do this job.",1109.5924v2
2011-10-09,Lorentzian similarity manifold,"If an $m+2$-manifold $M$ is locally modeled on $\RR^{m+2}$ with coordinate
changes lying in the subgroup $G=\RR^{m+2}\rtimes ({\rO}(m+1,1)\times \RR^+)$
of the affine group ${\rA}(m+2)$, then $M$ is said to be a \emph{Lorentzian
similarity manifold}. A Lorentzian similarity manifold is also a conformally
flat Lorentzian manifold because $G$ is isomorphic to the stabilizer of the
Lorentz group ${\rPO}(m+2,2)$ which is the full Lorentzian group of the Lorentz
model $S^{2n+1,1}$. It contains a class of Lorentzian flat space forms. We
shall discuss the properties of compact Lorentzian similarity manifolds using
developing maps and holonomy representations.",1110.1792v1
2011-10-10,Induced Lorentz-violating terms at finite temperature,"We study the radiatively induced Lorentz-violating terms at finite
temperature, namely, the higher-derivative term and the Chern-Simons term.
These terms are induced by integrating out the fermions coupled to the
coefficient $g^{\kappa\mu\nu}$. The calculation of the resulting expressions is
performed by using the derivative expansion and the Matsubara formalism. The
Chern-Simons terms is nonzero only at finite temperature, whereas the
higher-derivative term is finite at zero temperature, however, it goes to zero
as the temperature grows to infinity. We also obtain a higher-derivative
Chern-Simons term, nevertheless, it vanishes asymptotically.",1110.2127v2
2011-10-26,Effect of dynamic and static friction on an asymmetric granular piston,"We investigate the influence of dry friction on an asymmetric, granular
piston of mass $M$ composed of two materials undergoing inelastic collisions
with bath particles of mass $m$. Numerical simulations of the Boltzmann-Lorentz
equation reveal the existence of two scaling regimes depending on the strength
of friction. In the large friction limit, we introduce an exact model giving
the asymptotic behavior of the Boltzmann-Lorentz equation. For small friction
and for large mass ratio $M/m$, we derive a Fokker-Planck equation for which
the exact solution is also obtained. Static friction attenuates the motor
effect and results in a discontinuous velocity distribution.",1110.5831v1
2011-12-24,The Källén-Lehmann representation for Lorentz-violating field theory,"We consider field-theoretic models, one consisting purely of scalars, the
other also involving fermions, that couple to a set of constant background
coupling coefficients transforming as a symmetric observer Lorentz two-tensor.
We show that the exact propagators can be cast in the form of a
K\""all\'en-Lehmann representation. We work out the resulting form of the
Feynman propagators and the equal-time field commutators, and derive sum rules
for the spectral density functions.",1112.5739v2
2012-02-21,On spacelike surfaces in 4-dimensional Lorentz-Minkowski spacetime through a lightcone,"On any spacelike surface in a lightcone of four dimensional Lorentz-Minkowski
space a distinguished smooth function is considered. It is shown how both
extrinsic and intrinsic geometry of such a surface is codified by this
function. The existence of a local maximum is assumed to decide when the
spacelike surface must be totally umbilical, deriving a Liebmann type result.
Two remarkable families of examples of spacelike surfaces in a lightcone are
explicitly constructed. Finally, several results which involve the first
eigenvalue of the Laplace operator of a compact spacelike surface in a
lightcone are obtained.",1202.4589v1
2012-03-01,Lorentz invariant CPT violation: Particle and antiparticle mass splitting,"The interpretation of neutrino oscillation data has led to the question
whether, in principle, an antiparticle like antineutrino can have a different
mass than its particle. In the framework of a Lorentz invariant CPT violation,
which is based on the nonlocal interaction vertex and characterized by the
infrared divergent form factor, we present an explicit Lagrangian model for the
fermion and antifermion mass splitting.",1203.0267v1
2012-03-03,Unified Description of Nambu-Goldstone Bosons without Lorentz Invariance,"Using the effective Lagrangian approach, we clarify general issues about
Nambu-Goldstone bosons without Lorentz invariance. We show how to count their
number and study their dispersion relations. Their number is less than the
number of broken generators when some of them form canonically conjugate pairs.
The pairing occurs when the generators have a nonzero expectation value of
their commutator. For non-semi-simple algebras, central extensions are
possible. The underlying geometry of the coset space in general is partially
symplectic.",1203.0609v3
2012-03-20,Isophote curves on spacelike surfaces in Lorentz-Minkowski space E31,"Isophote curve consists of a locus of surface points whose normal vectors
make a constant angle with a fixed vector (the axis). In this paper, we define
an isophote curve on a spacelike surface in Lorentz-Minkowski space and then
find its axis as timelike and spacelike vectors via the Darboux frame. Besides,
we give some characterizations concerning isophote curve and its axis.",1203.4388v2
2012-06-12,Cosmological aspects of a vector field model,"We have studied a DGP-inspired braneworld scenario where the idea of Lorentz
invariance violation has been combined into a specifying preferred frame that
embed a dynamical normal vector field to brane. We propose the Lorentz
violating DGP brane models with enough parameters can explain crossing of
phantom divide line. Also we have considered the model for proper cosmological
evolution that is according to the observed behavior of the equation of state.
In other view point, we have described a Rip singularity solution of model that
occur in this model.",1206.2438v3
2012-06-12,4-Spinors and a Projection onto 3+1 Spacetime,"We write down an explicit projection that maps any given 4-spinor to a point
in 3+1 spacetime while commuting with the Lorentz action. This suggests that a
Lorentz invariant theory - including spacetime itself - has a more natural
expression in terms of these primitive spinor variables, while an ordinary
spacetime interpretation may be obtained by projecting solutions. Using this
projection, we show how the real components of a given 4-spinor reference a
point in a five dimensional spacetime.",1206.2458v2
2012-06-26,Sedeonic theory of massless fields,"In present paper we develop the description of massless fields on the basis
of space-time algebra of sixteen-component sedeons. The generalized sedeonic
second-order equation for unified gravitoelectromagnetic (GE) field describing
simultaneously gravity and electromagnetism is proposed. The second-order
relations for the GE field energy, momentum and Lorentz invariants are derived.
We consider also the generalized sedeonic first-order equation for the massless
neutrino field. The second-order relations for the neutrino potentials
analogues to the Pointing theorem and Lorentz invariant relations in
gravitoelectromagnetism are also derived.",1206.5969v1
2012-07-12,Hall effect for indirect excitons in an inhomogeneous magnetic field,"We study the effect of non-homogeneous out-of-plane magnetic field on the
behaviour of 2D spatially indirect excitons. Due to the difference of magnetic
field acting on electrons and holes the total Lorentz force affecting the
center of mass motion of an indirect exciton appears. Consequently, an indirect
exciton acquires an effective charge proportional to the gradient of the
magnetic field. The appearance of the Lorentz force causes the Hall effect for
neutral bosons which can be detected by measurement of the spatially
inhomogeneous blueshift of the photoluminescence using counter-flow experiment.",1207.2880v2
2012-07-25,A Lorentz invariant doubled worldsheet theory,"We propose a Lorentz invariant version of Tseytlin's doubled worldsheet
theory that makes T-duality covariance of the string manifest. This theory can
be derived as a gauge fixed version of Buscher's gauging procedure, in which
the left-over gauge field component acts as a Lagrange multiplier. This
description can naturally account for fractional linear O(D,D) transformations
of the metric and b-field. It is capable of describing non-geometric
backgrounds; geometric and non-geometric fluxes are encoded in the doubled
anti-symmetric tensor field strength.",1207.6110v2
2012-07-26,Equivalence of total force (and torque) for two formulations of the Lorentz law,"Two formulations of the Lorentz law of force in classical electrodynamics
yield identical results for the total force (and total torque) of radiation on
a solid object. The object may be surrounded by the free space or immersed in a
transparent dielectric medium such as a liquid. We discuss the relation between
these two formulations and extend the proof of their equivalence to the case of
solid objects immersed in a transparent medium.",1207.6152v1
2012-08-28,Generalized uncertainty principles and quantum field theory,"Quantum mechanics with a generalized uncertainty principle arises through a
representation of the commutator $[\hat{x}, \hat{p}] = i f(\hat{p})$. We apply
this deformed quantization to free scalar field theory for $f_\pm =1\pm \beta
p^2$. The resulting quantum field theories have a rich fine scale structure.
For small wavelength modes, the Green's function for $f_+$ exhibits a
remarkable transition from Lorentz to Galilean invariance, whereas for $f_-$
such modes effectively do not propagate. For both cases Lorentz invariance is
recovered at long wavelengths.",1208.5761v1
2012-08-31,Obtaining Maxwell's equations heuristically,"Starting from the experimental fact that a moving charge experiences the
Lorentz force and applying the fundamental principles of simplicity (first
order derivatives only) and linearity (superposition principle), we show that
the structure of the microscopic Maxwell equations for the electromagnetic
fields can be deduced heuristically by using the transformation properties of
the fields under space inversion and time reversal. Using the experimental
facts of charge conservation and that electromagnetic waves propagate with the
speed of light together with Galileo invariance of the Lorentz force allows us
to introduce arbitrary electrodynamic units naturally.",1208.6409v1
2012-09-14,Transverse Polarization of the Nucleon in Parton Picture,"The proton's transverse polarization structure is examined in terms of the
Lorentz-covariant Pauli-Lubanski vector in QCD. We find that there are
contributions from leading, subleading, and next-to-subleading partonic
contributions in the light-front system of coordinates. The subleading and
next-to-subleading contributions are related to the leading one through Lorentz
symmetry. And the leading contribution obeys a simple partonic angular momentum
sum rule that gives a clear physical interpretation to a relation known
previously.",1209.3246v1
2012-09-20,Six-dimensional Methods for Four-dimensional Conformal Field Theories II: Irreducible Fields,"This note supplements an earlier paper on conformal field theories. There it
was shown how to construct tensor, spinor, and spinor-tensor primary fields in
four dimensions from their counterparts in six dimensions, where conformal
transformations act simply as SO(4,2) Lorentz transformations. Here we show how
to constrain fields in six dimensions so that the corresponding primary fields
in four dimensions transform according to irreducible representations of the
four-dimensional Lorentz group, even when the irreducibility conditions on
these representations involve the four-component Levi-Civita tensor
$\epsilon_{\mu\nu\rho\sigma}$.",1209.4659v2
2012-10-03,Weighted convolution inequalities for radial functions,"We obtain convolution inequalities in Lebesgue and Lorentz spaces with power
weights when the functions involved are assumed to be radially symmetric. We
also present applications of these results to inequalities for Riesz potentials
of radial functions in weighted Lorentz spaces and embedding theorems for
radial Besov spaces with power weights.",1210.1206v2
2012-10-05,Lorentz spaces with variable exponents,"We introduce Lorentz spaces $L_{p(\cdot),q}(\R^n)$ and
$L_{p(\cdot),q(\cdot)}(\R^n)$ with variable exponents. We prove several basic
properties of these spaces including embeddings and the identity
$L_{p(\cdot),p(\cdot)}(\R^n)=L_{p(\cdot)}(\R^n)$. We also show that these
spaces arise through real interpolation between $L_{\p}(\R^n)$ and
$L_\infty(\R^n)$. Furthermore, we answer in a negative way the question posed
in Diening, H\""ast\""o, and Nekvinda (2004) whether the Marcinkiewicz
interpolation theorem holds in the frame of Lebesgue spaces with variable
integrability.",1210.1738v2
2012-10-08,Consequences for special relativity theory of restoring Einstein's neglected additive constants in the Lorentz Transformation,"Evaluation of the additive constants in the space-time Lorentz transformation
equations required, according to Einstein, to correctly describe synchronised
clocks at different spatial locations, reveals the spurious and unphysical
nature of the 'relativity of simultaneity' and 'length contraction' effects of
conventional special relativity. Unlike time dilation, there is no experimental
evidence for these putative effects. Only a universal (position independent)
time dilation effect for different inertial frames distinguishes special from
Galilean relativity.",1210.2270v1
2012-10-15,Minimal fields of canonical dimensionality are free,"It is shown that in a scale-invariant relativistic field theory, any field
$\psi_n$ belonging to the $(j,0)$ or $(0,j)$ representations of the Lorentz
group and with dimensionality $d=j+1$ is a free field. For other field types
there is no value of the dimensionality that guarantees that the field is free.
Conformal invariance is not used in the proof of these results, but it gives
them a special interest; as already known and as shown here in an appendix, the
only fields in a conformal field theory that can describe massless particles
belong to the $(j,0)$ or $(0,j)$ representations of the Lorentz group and have
dimensionality $d=j+1$. Hence in conformal field theories massless particles
are free.",1210.3864v1
2012-10-14,Local Lorentz transformation and exact spherically symmetric vacuum solutions in f(T) gravity theories,"Applying a non-diagonal spherically symmetric tetrad field having arbitrary
function, $S(r)$, that is corresponding to local Lorentz transformation, to the
field equations of f(T) gravity theories.
  An analytic vacuum solutions with constants of integration are derived. These
constants are studied by calculating the total conserved charge associated to
each solution. The study has shown that the obtained solutions represent
Schwarzschild-Ads spacetime.",1210.4470v2
2012-10-18,Experimental search for a Lorentz invariant spacetime granularity: Possibilities and bounds,"We consider a search for phenomenological signatures from an hypothetical
space-time granularity that respects Lorentz invariance. The model is based on
the idea that the metric description of Einstein's gravity corresponds to a
hydrodynamic characterization of some deeper underlying structure, and that
Einstein's gravity is thus to be seen as emergent. We present the specific
phenomenological model in detail and analyze the bounds on its free parameters
established by a experiment specifically designed to test this model.",1210.5223v2
2012-10-27,"Comment on ""Trouble with the Lorentz Law of Force: Incompatibility with Special Relativity and Momentum Conservation""","This Comment addresses a recent paper by M. Mansuripur (Phys. Rev. Lett. 108,
193901 (2012)), who claims that the Lorentz law of force should be abandoned
because it violates relativity. The Comment argues that this is not necessarily
the case and also takes issue with Manusripur's approach to classical
electromagnetism.",1210.7344v2
2012-11-15,Trouble with the Lorentz Law of Force: Response to Critics,"In a recent paper [arXiv:1205.0096], we questioned the validity of the
Lorentz law of force in the presence of material media that contain electric
and/or magnetic dipoles. A number of authors have criticized our methods and
conclusions. This paper is an attempt at answering the critics and elaborating
the relevant issues in some detail.",1211.3485v1
2012-11-28,New tests of local Lorentz invariance and local position invariance of gravity with pulsars,"New tests are proposed to constrain possible deviations from local Lorentz
invariance and local position invariance in the gravity sector. By using
precise timing results of two binary pulsars, i.e., PSRs J1012+5307 and
J1738+0333, we are able to constrain (strong-field) parametrized post-Newtonian
parameters $\hat{\alpha}_1$, $\hat{\alpha}_2$, $\hat{\xi}$ to high precision,
among which, $|\hat{\xi}| < 3.1\times10^{-4}$ (95% C.L.) is reported here for
the first time.",1211.6558v1
2013-01-15,Lorentz completion of effective string action,"In the presence of a confining flux tube between a pair of sources the vacuum
is no longer Poincare' invariant. This symmetry is nonlinearly realized in the
effective string action. A general method for finding a large class of Lorentz
invariant contributions to the action is described. The relationship between
this symmetry and diffeomorphism invariance is further investigated.",1301.3437v2
2013-01-20,The Search for Neutrino-Antineutrino Mixing Resulting from Lorentz Invariance Violation using neutrino interactions in MINOS,"We searched for a sidereal modulation in the rate of neutrinos produced by
the NuMI beam and observed by the MINOS far detector. The detection of such
harmonic signals could be a signature of neutrino-antineutrino mixing due to
Lorentz and CPT violation as described by the Standard Model Extension
framework. We found no evidence for these sidereal signals and we placed limits
on the coefficients in this theory describing the effect. This is the first
report of limits on these neutrino-antineutrino mixing coefficients.",1301.4684v1
2013-01-23,Constraints on relativity violations from gamma-ray bursts,"Tiny violations of the Lorentz symmetry of relativity and the associated
discrete CPT symmetry could emerge in a consistent theory of quantum gravity
such as string theory. Recent evidence for linear polarization in gamma-ray
bursts improves existing sensitivities to Lorentz and CPT violation involving
photons by factors ranging from ten to a million.",1301.5367v1
2013-02-06,Dixmier traces and extrapolation description of noncommutative Lorentz spaces,"We study the relationships between Dixmier traces, zeta-functions and traces
of heat semigroups beyond the dual of the Macaev ideal and in the general
context of semifinite von Neumann algebras. We show that the correct framework
for this investigation is that of operator Lorentz spaces possessing an
extrapolation description. We demonstrate the applicability of our results to
H\""ormander-Weyl pseudo-differential calculus. In that context, we prove that
the Dixmier trace of a pseudo-differential operator coincide with the `Dixmier
integral' of its symbol.",1302.1367v2
2013-02-21,Remarks on the Aharonov-Casher dynamics in a CPT-odd Lorentz-violating background,"The Aharonov-Casher problem in the presence of a Lorentz-violating background
nonminimally coupled to a spinor and a gauge field is examined. Using an
approach based on the self-adjoint extension method, an expression for the
bound state energies is obtained in terms of the physics of the problem by
determining the self-adjoint extension parameter.",1302.5362v3
2013-04-17,Quantum Holonomies based on the Lorentz-violating tensor background,"We study geometric quantum phases corresponding to analogues of the Anandan
quantum phase [J. Anandan, Phys. Lett. A {\bf138}, 347 (1989)] based on a
possible scenario of the Lorentz symmetry violation background in a tensor
background. We also show that quantum holonomies associated with the analogue
of the Anandan quantum phase can be determined, and discuss a way of performing
one-qubit quantum gates by analogy with the holonomic quantum computation [P.
Zanardi and M. Rasetti, Phys. Lett. A {\bf264}, 94 (1999)].",1304.4833v1
2013-04-22,Aspects of Quantum Corrections in a Lorentz-violating Extension of the Abelian Higgs Model,"We investigate new aspects related to the abelian gauge-Higgs model with the
addition of the Carroll-Field-Jackiw term. We focus on one-loop quantum
corrections to the photon and Higgs sectors due to spontaneous breaking of
gauge symmetry and show that new finite and definite Lorentz-breaking terms are
induced. Specifically in the gauge sector, a CPT-even aether term is induced.
Besides, aspects of the one-loop renormalization of the background vector
dependent terms are discussed.",1304.6016v2
2013-05-03,On the Origin of Gravitational Lorentz Covariance,"We provide evidence that general relativity is the unique spatially covariant
effective field theory of the transverse, traceless graviton degrees of
freedom. The Lorentz covariance of general relativity, having not been assumed
in our analysis, is thus plausibly interpreted as an accidental or emergent
symmetry of the gravitational sector.",1305.0822v2
2013-04-13,An investigation of Lorentz transformation,"A new method of derivation of Lorentz Transformation (LT) is given based on
both axioms of special relativity (SR) and physical intuitions. The essence of
the transformation is established and the crucial role played by the
presumptions is presented for clarification. I consider the most general form
of transformations between two sets of events in two inertial reference frames
and use the most basic properties expected from such a transformation together
with the principle of the constancy of the velocity of light to derive LT. The
method is very simple, succinct and useful for students trying a better
understanding of the subject.",1305.5212v1
2013-05-27,Current conservation in charge conjugation parity time reversal symmetry (CPT) violating gauge-invariant nonlocal Thirring model,"Charge conjugation, parity transformation and time reversal symmetry (CPT)
violation and Lorentz invariance can coexist in the framework of non-local
field theory. In this article we have proposed a class of Charge conjugation,
parity transformation and time reversal symmetry (CPT) violating Lorentz
invariant nonlocal gauge-invariant models, which can be termed as non-local
Thirring models. The conserved currents in this aspect are obtained.",1305.6087v3
2013-06-02,The 5D to 4D projection model applied as a Lepton to Galaxy Creation model,"The 5D to 4D projection is presented in a simple geometry giving the Perelman
Theorem, resulting in a 3D doughnut structure for the space manifold of the
Lorentz space-time. It is shown that in the lowest quantum state, this Lorentz
manifold confines and gives the de Broglie leptons from the massless 5D
e-trinos. On the scale of the universe, it allows for a model for the creation
of galaxies.",1306.0815v1
2013-06-10,Spin-Gauge Theory of Gravity with Higgs-field Mechanism,"We propose a Lorentz-covariant Yang-Mills spin-gauge theory, where the
function valued Dirac matrices play the role of a non-scalar Higgs-field. As
symmetry group we choose $SU(2) \times U(1)$. After symmetry breaking a
non-scalar Lorentz-covariant Higgs-field gravity appears, which can be
interpreted within a classical limit as Einstein's metrical theory of gravity,
where we restrict ourselves in a first step to its linearized version.",1306.2085v1
2013-06-25,Invariance of Spooky Action at a Distance in Quantum Entanglement under Lorentz Transformation,"We study the mechanism by which the particle-antiparticle entangled state
collapses instantaneously at a distance. By making two key assumptions, we are
able to show not only that instantaneous collapse of a wave function at a
distance is possible but also that it is an invariant quantity under Lorentz
transformation and compatible with relativity. In addition, we will be able to
detect in which situation a many-body entangled system exhibits the maximum
collapse speed among its entangled particles. Finally we suggest that every
force in nature acts via entanglement.",1306.6071v2
2013-07-07,On purely real surfaces in Kaehler surfaces and Lorentz surfaces in Lorentzian Kaehler surfaces,"An immersion $\phi \colon M \to \tilde M$ of a manifold $M$ into an
indefinite Kaehler manifold $\tilde M$ is called purely real if the almost
complex structure $J$ on $\tilde M$ carries the tangent bundle of $M$ into a
transversal bundle. In this article we survey some recent results on purely
real surfaces in Kaehler surfaces as well as on Lorentz surfaces in Lorentzian
Kaehler surfaces.",1307.1874v1
2013-07-19,The KATRIN Experiment: Status and Outlook,"The KATRIN experiment, presently under construction in Karlsruhe, Germany,
will improve on previous laboratory limits on the neutrino mass by a factor of
ten. KATRIN will use a high-activity, gaseous T2 source and a very
high-resolution spectrometer to measure the shape of the high-energy tail of
the tritium-decay beta spectrum. The shape measurement will also be sensitive
to new physics, including sterile neutrinos and Lorentz violation. This report
summarizes recent progress in the experiment.",1307.5289v1
2013-07-19,Unitarity in higher-order Lorentz-invariance violating QED,"The unitarity in Lorentz invariance violating QED consisting of standard
fermions and higher-order photons of the Myers-Pospelov theory is studied. We
find ghost states associated to the higher-order character of the theory which
could render the $S$ matrix nonunitary. An explicit calculation to check
perturbative unitarity in the process of electron-positron scattering is
performed and it is found to be possible to preserve unitarity.",1307.5340v1
2013-07-22,Probing Physics beyond the Standard Model with He/Xe clock comparison experiments,"The comparison of the free precession of co-located 3He-129Xe spins (clock
comparison) enables us to search for very tiny nonmagnetic spin interactions.
With our setup we could establish new limits for Lorentz invariance violating
interactions of spins with a relic background field which permeates the
Universe and points in a preferred direction in space.",1307.5604v1
2013-07-15,A quantum mechanical interpretation for the relativity of the space-time,"In special relativity theory the physical quantities are generally expressed
as function of the velocity. In the particular case of an extended object, the
factor 1/gamma of Lorentz contraction of its length in the direction of motion
is written as a function of the velocity of the extended object. The same
happens with the Lorentz factor gamma of time interval dilation of a moving
clock. In this paper we show that when gamma is written as a function of the
relativistic energy of the considered object the resulting expressions for the
length and for the time interval suggest that the contraction of length as well
as the dilation of the time interval are manifestations of the wave behavior of
matter.",1307.6521v1
2013-10-11,Lorentz Transformation of Blackbody Radiation,"We present a simple calculation of the Lorentz transformation of the spectral
distribution of blackbody radiation at temperature T. Here we emphasize that T
is the temperature in the blackbody rest frame and does not change. We thus
avoid the confused and confusing question of how temperature transforms. We
show by explicit calculation that at zero temperature the spectral distribution
is invariant. At finite temperature we find the well known result familiar in
discussions of the the 2.7! K cosmic radiation.",1310.3238v1
2013-08-01,"Comment on ""Trouble with the Lorentz Law of Force: Incompatibility with Special Relativity and Momentum Conservation [arXiv:1205.0096]""","In this Comment it is shown that the principle of relativity is naturally
satisfied and there is no paradox if an independent physical reality is
attributed to the four-dimensional (4D) geometric quantities (GQs) and not, as
usual, to the 3D quantities. Hence, there is no need either for the change of
the expression for the Lorentz force, but as a 4D GQ, or for the introduction
of some ""hidden"" 3D quantities.",1310.5005v1
2013-10-28,A random flight process associated to a Lorentz gas with variable density in a gravitational field,"We investigate the random flight process that arises as the Boltzmann-Grad
limit of a random scatterer Lorentz gas with variable scatterer density in a
gravitational field. For power function densities we show how the parameters of
the model determine recurrence or transience of the vertical component of the
trajectory. Finally, our methods show that, with appropriate scaling of space,
time and the density of obstacles, the trajectory of the particle converges to
a diffusion with explicitly given parameters.",1310.7312v3
2013-11-01,On the proton radius problem,"The recent values of the proton charge radius obtained by means of
muonic-hydrogen laser spectroscopy are about $4\%$ different from the electron
scattering data. It has been suggested that the proton radius is actually
measured in different frames and that, starting from a non relativistic quark
model calculation, the Lorentz transformation of the form factors accounts
properly for the discepancy. We shall show that the relation between the charge
radii measured in different frames can be determined on very general grounds by
taking into account the Lorentz transformation of the charge density. In this
way, the discrepancy between muonic-hydrogen laser spectroscopy and electron
scattering data can be removed.",1311.0319v1
2013-11-13,Constraints on RG Flows from Holographic Entanglement Entropy,"We examine the RG flow of a candidate c-function, extracted from the
holographic entanglement entropy of a strip-shaped region, for theories with
broken Lorentz invariance. We clarify the conditions on the geometry that lead
to a break-down of monotonic RG flows as is expected for generic
Lorentz-violating field theories. Nevertheless we identify a set of simple
criteria on the UV behavior of the geometry which guarantee a monotonic
c-function. Our analysis can thus be used as a guiding principle for the
construction of monotonic RG trajectories, and can also prove useful for
excluding possible IR behaviors of the theory.",1311.3307v1
2013-11-18,A note on vortices from Lorentz-violating models,"We consider two self-dual abelian Higgs systems obtained from Lorentz
breaking symmetry models by dimensional reduction. For the first model, we show
that the self-dual equations are identical to those of Nielsen-Olesen vortices.
Also, we show that our vortices have electric charge. In the second case we
show that self-dual Chern-Simons-Higgs vortices without electric charge are
possible.",1311.4501v4
2013-11-20,Lorentz Invariant Berry Phase for a Perturbed Relativistic Four Dimensional Harmonic Oscillator,"We show the existence of Lorentz invariant Berry phases generated, in the
Stueckleberg-Horwitz-Piron manifestly covariant quantum theory (SHP), by a
perturbed four dimensional harmonic oscillator. These phases are associated
with a fractional perturbation of the azimuthal symmetry of the oscillator.
They are computed numerically by using time independent perturbation theory and
the definition of the Berry phase generalized to the framework of SHP
relativistic quantum theory.",1311.5002v2
2013-11-28,On Einstein-Cartan Theory: I. Kinematical description,"Equations of motion for general gravitational connection and orthonormal
coframe from the Einstein-Hilbert type action are derived. Our formulation does
not fix coframe to be tangential to spatial section hence Lorentz group is
still present as a part of gauge freedom. 3+1 decomposition introduces tangent
Minkowski structures hence Hamilton-Dirac approach to dynamics works with
Lorentz connection over the spatial section. The second class constraints are
analyzed and Dirac bracket is defined. Reduction of the phase space is
performed and canonical coordinates are introduced.",1311.7360v2
2013-12-20,Lorentz space estimates for vector fields with divergence and curl in Hardy spaces,"In this note, we establish the estimate on the Lorentz space $L(3/2,1)$ for
vector fields in bounded domains under the assumption that the normal or the
tangential component of the vector fields on the boundary vanishing. We prove
that the $L(3/2,1)$ norm of the vector field can be controlled by the norms of
its divergence and curl in the atomic Hardy spaces and the $L^1$ norm of the
vector field itself.",1312.5823v1
2014-01-15,Unitarity in a Lorentz symmetry breaking model with higher-order operators,"We analyze the unitarity of a modified QED with higher-order terms that
violate Lorentz symmetry. We make an explicit calculation to verify unitarity
at the one-loop level. As expected we find negative norm states that could in
principle lead to a violation of unitarity. However, we show that these states
become massive in Euclidean space and do not contribute to the discontinuity.",1401.3752v2
2014-02-13,Lorentz Invariance Violation and Modified Hawking Fermions Tunneling from Black Strings,"Recently the modified Dirac equation with Lorentz invariance violation has
been proposed, which would be helpful to resolve some issues in quantum gravity
theory and high energy physics. In this paper, the modified Dirac equation has
been generalized in curved spacetime, and then fermion tunneling of black
strings is researched under this correctional Dirac field theory. We also use
semi-classical approximation method to get correctional Hamilton-Jacobi
equation, so that the correctional Hawking temperature and correctional black
hole's entropy are derived.",1402.3047v1
2013-12-17,Michelson interferometer null may confirm transverse Doppler Effect,"We analyze fringe formation within Michelson-like experiments as viewed by
relativistic inertial observers. Our analysis differs from previous work
because we include optical misalignment of the beamsplitter of the
interferometer due to the anamorphic geometry of relativistic Lorentz
contraction. We conclude that inertial frame equivalence of Michelson-like
experiments provide verification of the transverse Doppler Effect and exclude
any model incorporating the relativistic Lorentz contraction effect.",1402.4781v2
2014-02-27,Diffusion in the Lorentz gas,"The Lorentz gas, a point particle making mirror-like reflections from an
extended collection of scatterers, has been a useful model of deterministic
diffusion and related statistical properties for over a century. This survey
summarises recent results, including periodic and aperiodic models, finite and
infinite horizon, external fields, smooth or polygonal obstacles, and in the
Boltzmann-Grad limit. New results are given for several moving particles and
for obstacles with flat points. Finally, a variety of applications are
presented.",1402.7010v3
2014-02-28,Isometries of Lorentz surfaces and convergence groups,"We study the isometry group of a globally hyperbolic spatially compact
Lorentz surface. Such a group acts on the circle, and we show that when the
isometry group acts non properly, the subgroups of
$\mathrm{Diff}(\mathbb{S}^1)$ obtained are semi conjugate to subgroups of
finite covers of $\mathrm{PSL}(2,\mathbb{R})$ by using convergence groups.
Under an assumption on the conformal boundary, we show that we have a conjugacy
in $\mathrm{Homeo}(\mathbb{S}^1)$.",1402.7179v2
2014-02-28,Sections of functions and Sobolev type inequalities,"We study functions of two variables whose sections by the lines parallel to
the coordinate axis satisfy Lipschitz condition of the order $0<\a\le 1.$ We
prove that if for a function $f$ the $\operatorname{Lip} \a-$ norms of these
sections belong to the Lorentz space $L^{p,1}(\R) \,(p=1/\a),$ then $f$ can be
modified on a set of measure zero so as to become bounded and uniformly
continuous on $\R^2.$ For $\a=1$ this gives an extension of Sobolev's theorem
on continuity of functions of the space $W_1^{2,2}(\R^2)$. We show that the
exterior $L^{p,1}-$ norm cannot be replaced by a weaker Lorentz norm $L^{p,q}$
with $q>1$.",1402.7192v1
2014-02-28,Synthetic Lorentz force in classical atomic gases via Doppler effect and radiation pressure,"We theoretically predict a novel type of synthetic Lorentz force for
classical (cold) atomic gases, which is based on the Doppler effect and
radiation pressure. A fairly uniform and strong force can be constructed for
gases in macroscopic volumes of several cubic millimeters and more. This opens
the possibility to mimic classical charged gases in magnetic fields, such as
those in a tokamak, in cold atom experiments.",1402.7251v2
2014-04-16,Derivation of the Fick's Law for the Lorentz Model in a low density regime,"We consider the Lorentz model in a slab with two mass reservoirs at the
boundaries. We show that, in a low density regime, there exists a unique
stationary solution for the microscopic dynamics which converges to the
stationary solution of the heat equation, namely to the linear profile of the
density. In the same regime the macroscopic current in the stationary state is
given by the Fick's law, with the diffusion coefficient determined by the
Green-Kubo formula.",1404.4186v2
2014-08-18,Low-order geometric actions with fields a metric and a matter field of arbitrary rank (undergraduate honors thesis),"We classify invariant Lagrangians of the form
$L(g_{ij},g_{ij,k},g_{ij,kl},D_I,D_{I,j})$ depending at most quadratically on
the variables $g_{ij,k},g_{ij,kl}$ and $D_I,D_{I,j}$, where $g$ is a Lorentz
metric and $D$ is a tensor field of arbitrary rank on a smooth manifold. As a
corollary, we prove a conjecture of Bray's regarding the classification of
certain variational principles with variables a Lorentz metric and an affine
connection.",1408.4415v2
2014-08-20,The predual and John-Nirenberg inequalities on generalized BMO martingale spaces,"In this paper we introduce the generalized BMO martingale spaces by stopping
time sequences, which enable us to characterize the dual spaces of martingale
Hardy-Lorentz spaces $H_{p,q}^s$ for $0<p\leq1, 1<q<\infty$. Moreover, by
duality we obtain a John-Nirenberg theorem for the generalized BMO martingale
spaces when the stochastic basis is regular. We also extend the boundedness of
fractional integrals to martingale Hardy-Lorentz spaces.",1408.4641v1
2014-10-14,Diffusive limit for the random Lorentz gas,"We review some recent results concerning the derivation of the diffusion
equation and the validation of Fick's law for the microscopic model given by
the random Lorentz Gas. These results are achieved by using a linear kinetic
equation as an intermediate level of description between our original
mechanical system and the diffusion equation.",1410.3765v1
2014-10-19,On the Lorentz invariance of the Square root Klein-Gordon Equation,"We show that the Born's rule is incompatible with Lorentz symmetry of the
Square Root Klein-Gordon equation (SRKG equation). It has been demonstrated
that the Born rule must be modified in relativistic regime if one wishes to
keep the SRKG equation as the correct equation for describing quantum behavior.",1410.5041v3
2014-10-22,Short-range gravity and Lorentz violation,"Comparatively few searches have been performed for violations of local
Lorentz invariance in the pure-gravity sector. We show that tests of
short-range gravity are sensitive to a broad class of unconstrained and novel
signals that depend on the experimental geometry and on sidereal time.",1410.6162v2
2014-11-17,Unitarity and non-relativistic potential energy in a higher-order Lorentz symmetry breaking electromagnetic model,"The Lorentz-violating model proposed by Myers and Pospelov suffers from a
higher-derivative pathology due to a dimension-5 operator. In particular, its
electromagnetic sector exhibits an spectrum which contains, in addition to an
expected massless photon, ghost contributions that could (in principle) spoil
the unitarity of the model. We find that unitarity at tree-level can be assured
for pure spacelike, timelike and lightlike background four-vectors (the last
two under restrictions upon the allowed momenta). We then analyze the
non-relativistic interparticle potential energy behavior for different
background four-vectors and compare to the usual Coulomb potential.",1411.4549v1
2014-12-15,Phenomenology of theories of gravity without Lorentz invariance: the preferred frame case,"Theories of gravitation without Lorentz invariance are candidates of
low-energy descriptions of quantum gravity. In this review we will describe the
phenomenological consequences of the candidates associated to the existence of
a preferred time direction",1412.4828v2
2014-12-16,Relativistic geometric quantum phases from the Lorentz symmetry violation effects in the CPT-even gauge sector of Standard Model Extension,"We discuss the appearance of relativistic geometric quantum phases for a
Dirac neutral particle based on possible scenarios of the Lorentz symmetry
violation background in the CPT-even gauge sector of Standard Model Extension.
Relativistic analogues of the Anandan quantum phase [J. Anandan, Phys. Lett. A
138, 347 (1989)] are obtained based on the the parity-even and parity-odd
sectors of the tensor $\left(K_{F}\right)_{\mu\nu\alpha\beta}$.",1412.5080v1
2014-12-21,The Lorentz Anomaly via Operator Product Expansion,"The emergence of a critical dimension is one of the most striking features of
string theory. One way to obtain it is by demanding closure of the Lorentz
algebra in the light-cone gauge quantisation, as discovered for bosonic strings
more than fourty years ago. We give a detailed derivation of this classical
result based on the operator product expansion on the Lorentzian world-sheet.",1412.6838v1
2014-12-25,Spinor Structure and Modulo 8 Periodicity,"Spinor structure is understood as a totality of tensor products of
biquaternion algebras, and the each tensor product is associated with an
irreducible representation of the Lorentz group. A so-defined algebraic
structure allows one to apply modulo 8 periodicity of Clifford algebras on the
system of real and quaternionic representations of the Lorentz group. It is
shown that modulo 8 periodic action of the Brauer-Wall group generates modulo 2
periodic relations on the system of representations, and all the totality of
representations under this action forms a self-similar fractal structure. Some
relations between spinors, twistors and qubits are discussed in the context of
quantum information and decoherence theory.",1412.7802v1
2014-12-29,Search for Lorentz violation in short-range gravity,"A search for sidereal variations in the force between two planar tungsten
oscillators separated by about 80 microns sets the first experimental limits on
Lorentz violation involving quadratic couplings of the Riemann curvature,
consistent with no effect at the level of $10^{-7}$ m$^2$.",1412.8362v2
2015-01-30,Gravity Effects on Antimatter in the Standard-Model Extension,"The gravitational Standard-Model Extension (SME) is the general field-theory
based framework for the analysis of CPT and Lorentz violation. In this work we
summarize the implications of Lorentz and CPT violation for antimatter gravity
in the context of the SME. Implications of various attempts to place indirect
limits on anomalous antimatter gravity are considered in the context of
SME-based models.",1501.07660v1
2015-02-21,Aspects of CPT-even Lorentz-symmetry violating physics in a supersymmetric scenario,"Background fermion condensates in a landscape dominated by global SUSY are
reassessed in connection with a scenario where Lorentz symmetry is violated in
the bosonic sector (actually, the photon sector) by a $CPT$-even $k_F$-term. An
effective photonic action is discussed that originates from the supersymmetric
background fermion condensates. Also, the photino mass emerges in terms of a
particular condensate contrary to what happens in the $k_{AF}$-violation.
Finally, the interparticle potential induced by the effective photonic action
is investigated and a confining profile is identified.",1502.06126v1
2015-02-28,Lorentz Coherence and the Proton Form Factor,"The dipole cutoff behavior for the proton form factor has been and still is
one of the major issues in high-energy physics. It is shown that this dipole
behavior comes from the coherence between the Lorentz contraction of the proton
size and the decreasing wavelength of the incoming photon signal. The
contraction rates are the same for both cases. This form of coherence is
studied also in the momentum-energy space. The coherence effect in this space
can be explained in terms of two overlapping wave functions.",1503.00069v1
2014-09-01,Lorentz covariance and gauge invariance in the proton spin problem,"In this brief note insightful remarks are made on the controversy on the
decomposition of the proton spin into the spin and orbital angular momenta of
quarks and gluons. It is argued that the difference in the perception on the
nature of the problem is the main reason for the persistent disputes. There is
no decomposition that simultaneously satisfies the twin principles of manifest
Lorentz covariance and gauge invariance, and partial considerations hide likely
inconsistencies. It is suggested that field equations and matter (i. e.
electron in QED and quarks in QCD) equations must be analyzed afresh rather
than beginning with the expressions of total angular momentum; canonical or
otherwise.",1503.02053v1
2015-03-20,Extended Lorentz cones and variational inequalities on cylinders,"Solutions of a variational inequality are found by giving conditions for the
monotone convergence with respect to a cone of the Picard iteration
corresponding to its natural map. One of these conditions is the isotonicity of
the projection onto the closed convex set in the definition of the variational
inequality. If the closed convex set is a cylinder and the cone is an extented
Lorentz cone, then this condition can be dropped because it is automatically
satisfied. The obtained result is further particularized for unbounded box
constrained variational inequalities. For this case a numerical example is
presented.",1503.06119v1
2015-04-08,Getting the Lorentz transformations without requiring an invariant speed,"The structure of the Lorentz transformations follows purely from the absence
of privileged inertial reference frames and the group structure (closure under
composition) of the transformations---two assumptions that are simple and
physically necessary. The existence of an invariant speed is \textit{not} a
necessary assumption, and in fact is a consequence of the principle of
relativity (though the finite value of this speed must, of course, be obtained
from experiment). Von Ignatowsky derived this result in 1911, but it is still
not widely known and is absent from most textbooks. Here we present a
completely elementary proof of the result, suitable for use in an introductory
course in special relativity.",1504.02423v1
2015-04-28,Relativistic generalization of the Born rule,"We have shown that the Born rule $(\rho=|\psi|^{2})$ is inconsistent with
Lorentz symmetry of the Salpeter equation (square root Klein-Gordon equation).
So we find relativistic modification of the Born rule as
$\rho=\frac{1}{2mc^{2}}(|\sqrt{\widehat{H}-mc^{2}}\psi|^{2}+|\sqrt{\widehat{H}+mc^{2}}\psi|^{2})$
, which is consistent with Lorentz symmetry of this equation",1504.07582v2
2015-05-04,The Correlated Jacobi and the Correlated Cauchy-Lorentz ensembles,"We calculate the $k$-point generating function of the correlated Jacobi
ensemble using supersymmetric methods. We use the result for complex matrices
for $k=1$ to derive a closed-form expression for eigenvalue density. For real
matrices we obtain the density in terms of a twofold integral that we evaluate
numerically. For both expressions we find agreement when comparing with Monte
Carlo simulations. Relations between these quantities for the Jacobi and the
Cauchy-Lorentz ensemble are derived.",1505.00675v1
2015-05-16,"Weak Equivalence Principle, Lorentz Non-invariance, and Nuclear Decays","We consider three possible manifestations of physics beyond the Standard
Model, and the relations among them. These are Lorentz non-invariance (LNI),
violations of the Weak Equivalence Principle (WEP), and indications of
time-varying nuclear decay constants. We present preliminary results from a new
experiment indicating the presence of annual and subannual periodicities in
decay data, and discuss their implications for physics beyond the Standard
Model.",1505.04221v1
2015-05-22,"Functional Inequalities in Stratified Lie groups with Sobolev, Besov, Lorentz and Morrey spaces","The study of Sobolev inequalities can be divided in two cases: p = 1 and 1 <
p < +$\infty$. In the case p = 1 we study here a relaxed version of refined
Sobolev inequalities. When p > 1, using as base space classical Lorentz spaces
associated to a weight from the Arino-Muckenhoupt class Bp, we will study
Gagliardo-Nirenberg inequalities. As a by-product we will also consider
Morrey-Sobolev inequalities. These arguments can be generalized to many
different frameworks, in particular the proofs are given in the setting of
stratified Lie groups.",1505.05986v3
2015-06-11,Invariance principle for the periodic Lorentz gas in the Boltzmann-Grad limit,"In earlier work we showed that the particle displacement for the
multidimensional periodic Lorentz gas, in the limit of low scatterer density
(Boltzmann-Grad limit), satisfies a central limit theorem with superdiffusive
scaling. The present paper extends this result to a functional central limit
theorem, i.e., the weak convergence of the particle trajectory to Brownian
motion.",1506.03619v2
2015-06-25,On a prescribed mean curvature equation in Lorentz-Minkowski space,"We are interested in providing new results on a prescribed mean curvature
equation in Lorentz-Minkowski space set in the whole R^N, with N >2. We study
both existence and multiplicity of radial ground state solutions for p>1,
emphasizing the fundamental difference between the subcritical and the
supercritical case. We also study speed decay at infinity of ground states, and
give some decay estimates. Finally we provide a multiplicity result on the
existence of sign-changing bound state solutions for any p>1.",1506.07747v1
2015-07-02,Super Virasoro Algebras From Chiral Supergravity,"In this note, we construct Noether charges for the chiral supergravity, which
contains the Lorentz Chern-Simons term, by applying Wald's prescription to the
vielbein formalism. We investigate the AdS3/CFT2 correspondence by using the
vielbein formalism. The asymptotic symmetry group is carefully examined by
taking into account the local Lorentz transformation, and we construct super
Virasoro algebras with central extensions from the chiral supergravity.",1507.00486v2
2015-07-12,Aspects of Black Holes in Gravitational Theories with Broken Lorentz and Diffeomorphism Symmetries,"Since Stephen Hawking discovered that black holes emit thermal radiation,
black holes have become the theoretical laboratories for testing our ideas on
quantum gravity. This dissertation is devoted to the study of singularities,
the formation of black holes by gravitational collapse and the global structure
of spacetime. All our investigations are in the context of a recently proposed
approach to quantum gravity, which breaks Lorentz and diffeomorphism symmetries
at very high energies.",1507.03175v1
2015-07-21,"Where the Lorentz-Abraham-Dirac equation for the radiation reaction force fails, and why the ""proofs"" break down","We calculate the energy radiated coherently by a system of $N$ charged non
relativistic particles. It disagrees with the energy loss which is obtained if
one employs the Lorentz Abraham Dirac (LAD) equation for each particle, and
sums up the contributions. This fact was already clearly stated in the
classical literature long ago. The reason for the discrepancy is the omission
of the mixing terms in the Poynting vector. For some simple systems we present
a generalized equation for the radiation reaction force which cures this
defect. The counter examples show that the LAD equation cannot be generally
valid and that all ""proofs"" must fail somewhere. We demonstrate this failure
for some popular examples in the literature.",1507.05736v1
2015-07-23,Lorentz invariant deformations of momentum space,"In relative locality theories the geometric properties of phase space depart
from the standard ones given by the fact that spaces of momenta are linear
fibers over a spacetime base manifold. In particular here it is assumed that
the momentum space is non linear and can therefore carry non trivial metric and
composition law. We classify to second order all possible such deformations
that preserve Lorentz invariance. We show that such deformations still exists
after quotienting out by diffeomorphisms only if the non linear addition is non
associative.",1507.06459v1
2015-08-18,Fourier transform and regularity of characteristic functions,"Let $E$ be a bounded domain in $\mathbb R^d$. We study regularity property of
$\chi_E$ and integrability of $\widehat {\chi_E }$ when its boundary $\partial
E$ satisfies some conditions. At the critical case these properties are
generally known to fail. By making use of Lorentz and Lorentz-Sobolev spaces we
obtain the endpoint cases of the previous known results. Our results are based
on a refined version of Littlewood-Paley inequality, which makes it possible to
exploit cancellation effectively.",1508.04218v1
2015-08-21,Optical finite representation of the Lorentz group,"We present a class of photonic lattices with an underlying symmetry given by
a finite-dimensional representation of the 2+1D Lorentz group. In order to
construct such a finite-dimensional representation of a non-compact group, we
have to design a $\mathcal{PT}$-symmetric optical structure. Thus, the array of
coupled waveguides may keep or break $\mathcal{PT}$-symmetry, leading to a
device that behaves like an oscillator or directional amplifier, respectively.
We show that the so-called linear $\mathcal{PT}$-symmetric dimer belongs to
this class of photonic lattices.",1508.05419v1
2015-09-01,Radiation from a Relativistic Poynting Jet: some general considerations,"We provide estimates for the flux and maximum frequency of radiation produced
when the magnetic field in a relativistic, highly magnetized, jet is dissipated
and particles are accelerated using general considerations. We also provide
limits on the jet Lorentz factor and magnetization parameter from the observed
flux. Furthermore, using the Lorentz invariance of scalar quantities produced
with electromagnetic tensor, we provide constraints on particle acceleration,
and general features of the emergent radiation. We find that the spectrum below
the peak softens with decreasing frequency. This spectral feature might be one
way of identifying a magnetic jet.",1509.00479v1
2015-09-17,Remarks on a Lorentz-breaking 4D chiral gauge theory,"We investigate a Lorentz-violating chiral model composed by two fermions, a
complex scalar field and a gauge field. We show that by convenientely adjusting
the parameters of the model, it is possible to generate an unambiguous
Carroll-Field-Jackiw term and, at the same time, provide the cancelation of the
chiral anomaly. The renormalizability of the model is investigated and it is
shown that the same counterterms needed in the symmetric phase also renormalize
the model with broken symmetry.",1509.05352v3
2015-09-19,Analytic extension of Jorge-Meeks type maximal surfaces in Lorentz-Minkowski 3-space,"The Jorge-Meeks $n$-noid ($n\ge 2$) is a complete minimal surface of genus
zero with $n$ catenoidal ends in the Euclidean 3-space $\boldsymbol{R}^3$,
which has $(2\pi/n)$-rotation symmetry with respect to its axis. In this paper,
we show that the corresponding maximal surface $f_n$ in Lorentz-Minkowski
3-space $\boldsymbol{R}^3_1$ has an analytic extension $\tilde f_n$ as a
properly embedded zero mean curvature surface. The extension changes type into
a time-like (minimal) surface.",1509.05853v1
2015-09-15,"A study of stability of the ""plasma - beam"" system for the Lorentz plasma","The stability of the system comprising the cold immobile Lorentz plasma of
density $N_e$ and the directed nonrelativistic (velocity $\vec{V}$) electronic
beam of a small density $N'_e << N_e$ is investigated. The instability
increment of the system is found via analysis of the electric permittivity
$\epsilon(\omega)$ in the limiting case of $\omega$ being much greater than the
effective frequency of collisions. A conclusion is made that the system in
question is stable with respect to oscillations with relatively small values of
$\vec{k} \vec{V}$.",1510.03274v1
2015-10-19,Unifying Ghost-Free Lorentz-Invariant Lagrangians,"We present the details of the novel framework for Lagrangian field theories
that are Lorentz-invariant and lead to at most second order equations of
motion. The use of antisymmetric structure is of crucial importance. The
general ghost-free Lagrangians are constructed and then translated into the
language of differential forms. The ghost-freeness has a geometric nature. A
novel duality is proposed which generalizes the Hodge duality in Maxwell's
theory. We discuss how the well-established theories are reformulated and
propose many new theories.",1510.05496v2
2015-10-26,Causal characters of zero mean curvature surfaces of Riemann type in the Lorentz-Minkowski 3-space,"A zero mean curvature surface in the Lorentz-Minkowski 3-space is said to be
of Riemann-type if it is foliated by circles and at most countably many
straight lines in parallel planes. We classify all zero mean curvature surfaces
of Riemann-type according to their causal characters, and as a corollary, we
prove that if a zero mean curvature surface of Riemann-type has exactly two
causal characters, then the lightlike part of the surface is a part of a
straight line.",1510.07451v2
2015-10-04,Quasi-local conserved charges in Lorentz-diffeomorphism covariant theory of gravity,"In this paper, using the combined Lorentz-diffeomorphism symmetry, we find a
general formula for quasi-local conserved charge of the covariant gravity
theories in first order formalism of gravity. We simplify the general formula
for Lovelock theory of gravity. Afterwards, we apply the obtained formula on
BHT gravity to obtain energy and angular momentum of the rotating OTT black
hole solution in the context of this theory.",1511.00527v2
2015-11-16,Enhanced effects of the Lorentz invariance and Einstein equivalence principle violation in 229Th nuclear transition,"The Lorentz invariance and Einstein equivalence principle violating effects
in the narrow 7.8 eV transition in 229Th nucleus may be 100 000 times larger
than in atoms. This transition may be investigated using high precision laser
spectroscopy methods, has a very small width, and suppressed systematic
effects. Similar values of the effects are expected in 73 eV 235U nuclear
transition which is coming within the reach of the laser spectroscopy.
Mossbauer transitions give another possibility.",1511.04848v1
2015-10-22,Global estimates for quasilinear parabolic equations on Reifenberg flat domains and its applications to Riccati type parabolic equations with distributional data,"In this paper, we prove global weighted Lorentz and Lorentz-Morrey estimates
for gradients of solutions to the quasilinear parabolic equations:
$$u_t-\operatorname{div}(A(x,t,\nabla u))=\operatorname{div}(F),$$ in a bounded
domain $\Omega\times (0,T)\subset\mathbb{R}^{N+1}$, under minimal regularity
assumptions on the boundary of domain and on nonlinearity $A$. Then results
yields existence of a solution to the Riccati type parabolic equations:
$$u_t-\operatorname{div}(A(x,t,\nabla u))=|\nabla
u|^q+\operatorname{div}(F)+\mu,$$ where $q>1$ and $\mu$ is a bounded Radon
measure.",1511.06218v1
2015-11-24,"A generalized Weierstrass representation of Lorentzian surfaces in $\mathbb{R}^{2,2}$ and applications","We give a generalized Weierstrass formula for a Lorentz surface conformally
immersed in the four-dimensional space $\mathbb{R}^{2,2}$ using spinors and
Lorentz numbers. We also study the immersions of a Lorentzian surface in {\bf
the} Anti-de Sitter space (a pseudo-sphere in $\mathbb{R}^{2,2}$): we give a
new spinor representation formula and deduce the conformal description of a
flat Lorentzian surface in that space.",1511.07579v2
2015-11-25,Covariant Action for Type IIB Supergravity,"Taking clues from the recent construction of the covariant action for type II
and heterotic string field theories, we construct a manifestly Lorentz
covariant action for type IIB supergravity, and discuss its gauge fixing
maintaining manifest Lorentz invariance. The action contains a
(non-gravitating) free 4-form field besides the usual fields of type IIB
supergravity. This free field, being completely decoupled from the interacting
sector, has no physical consequence.",1511.08220v4
2016-01-18,Modified gravity and binary pulsars: the Lorentz violating case,"The dynamics of binary pulsars can be used to test different aspects of
gravitation. This is particularly important to constrain alternatives to
general relativity in regimes which are not probed by other methods. In this
short contribution, I will describe the case of theories of gravity without
Lorentz invariance. The latter are important in the context of quantum gravity
and modify the laws of gravity at basically all scales.",1601.04653v1
2016-02-08,Higher-derivative Lorentz-breaking terms in extended QED at the finite temperature,"In this paper we discuss finiteness and ambiguities of the higher-derivative
Lorentz-breaking terms in extended QED with a magnetic coupling at the finite
temperature. We find that, beside of the higher-derivative
Carroll-Field-Jackiw-like term and Myers-Pospelov term, many new terms arise in
a finite temperature case, but most of them vanish in high temperature limit.",1602.02570v2
2016-02-08,Uniform Acceleration in General Relativity,"We extend de la Fuente and Romero's defining equation for uniform
acceleration in a general curved spacetime from linear acceleration to the full
Lorentz covariant uniform acceleration. In a flat spacetime background, we have
explicit solutions. We use generalized Fermi-Walker transport to parallel
transport the Frenet basis along the trajectory. In flat spacetime, we obtain
velocity and acceleration transformations from a uniformly accelerated system
to an inertial system. We obtain the time dilation between accelerated clocks.
We apply our acceleration transformations to the motion of a charged particle
in a constant electromagnetic field and recover the Lorentz-Abraham-Dirac
equation.",1602.03067v1
2016-02-18,The local vicinity of spins sum for certain mass dimension one spinors,"It is well known that the usual formulation of Elko spinor fields leads to a
subtle Lorentz symmetry break encoded in the spin sums. Recently it was
proposed a redefinition in the dual structure, along with a given mathematical
device, which eliminate the Lorentz breaking term in the spin sums. In this
work we delve into the analysis of this mathematical device providing a solid
framework to the used method.",1602.05871v1
2016-03-03,The Fenchel-type inequality in the 3-dimensional Lorentz space and a Crofton formula,"We generalize the Fenchel theorem to strong spacelike (which means that the
tangent vector and the curvature vector span a spacelike 2-plane at each point)
closed curves with index 1 in the 3-dimensional Lorentz space, showing that the
total curvatures must be less than or equal to $2\pi$. A similar generalization
of the Fary-Milnor theorem is also obtained. We establish the Crofton formula
on the de Sitter 2-sphere which implies the above results.",1603.01311v1
2016-03-04,A Macroscopically Effective Lorentz Gauge Theory of Gravity,"Following the ideas of effective field theories, we derive classically
effective field equations of recently developed Lorentz gauge theory of
gravity. It is shown that Newton's gravitational constant emerges as an
effective coupling parameter if an extremely small length is integrated out of
the underlying theory. The linear version of the effective theory is shown to
be fully consistent with the Newtonian gravity. We also derive a numerical
solution for the interior of a star and show that in the non-linear regions,
the behavior of the effective theory deviates from the predictions of general
relativity.",1603.01655v2
2016-03-24,Recurrence properties of a special type of Heavy-Tailed Random Walk,"In the proof of the invariance principle for locally perturbed periodic
Lorentz process with finite horizon, a lot of delicate results were needed
concerning the recurrence properties of its unperturbed version. These were
analogous to the similar properties of Simple Symmetric Random Walk. However,
in the case of Lorentz process with infinite horizon, the analogous results for
the corresponding random walk are not known, either. In this paper, these
properties are ascertained for the appropriate random walk (this happens to be
in the non normal domain of attraction of the normal law). As a tool, an
estimation of the remainder term in the local limit theorem for the
corresponding random walk is computed.",1603.07586v1
2016-05-31,Meridian Surfaces with Parallel Normalized Mean Curvature Vector Field in Pseudo-Euclidean 4-space with Neutral Metric,"We construct a special class of Lorentz surfaces in the pseudo-Euclidean
4-space with neutral metric which are one-parameter systems of meridians of
rotational hypersurfaces with timelike or spacelike axis and call them meridian
surfaces. We give the complete classification of the meridian surfaces with
parallel mean curvature vector field. We also classify the meridian surfaces
with parallel normalized mean curvature vector. We show that in the family of
the meridian surfaces there exist Lorentz surfaces which have parallel
normalized mean curvature vector field but not parallel mean curvature vector.",1606.00047v1
2016-04-19,Relativistic transformation of temperature and Mosengeil-Ott's antinomy,"A not satisfactorily solved problem of relativistic transformation of
temperature playing the decisive role in relativistic thermal physics and
cosmology is reopened. It is shown that the origin of the so called
Mosengeil-Ott's antinomy and other aligned paradoxes are related to the wrong
understanding of physical meaning of temperature and application of Planck's
Ansatz of Lorentz's invariance of entropy. In the contribution we have thus
reintroduced and anew analyzed fundamental concepts of hotness manifold, fixed
thermometric points and temperature. Finally, on the basis of phenomenological
arguments the Lorentz invariance of temperature and relativistic
transformations of entropy are established.",1606.02127v1
2016-07-12,Emergence of gauge invariance from Nambu models,"In the framework of a hamiltonian nonperturbative approach we show that after
demanding current conservation together with the Gauss constraints at some
initial time in a nonabelian Nambu model, we recover the corresponding
Yang-Mills theory. In this way, the spontaneous Lorentz symmetry breaking
present in the Nambu model becomes unobservable and the Goldstone modes can be
identified with the corresponding gauge bosons.",1607.03350v1
2016-07-20,Tests of CPT symmetry in B0-B0bar mixing and in B0 to c cbar K0 decays,"Using the time dependences for the decays Y(4S) to B0B0bar to (ell^+- X)(c
cbar K_S,L), we determine the three CPT-sensitive parameters Re (z) and Im (z)
in B0-B0bar mixing and |Abar/A| in B0 to c cbar K0 decays. We find Im(z) =
0.010 +- 0.030 +- 0013, Re(z) = -0:065 +- 0.028 +- 0.014, and |Abar/A| = 0.999
+- 0.023 +- 0.017, in agreement with CPT symmetry. The Re(z) result provides a
limit on one component of Lorentz-symmetry violation.",1607.05882v2
2016-07-15,QCD emergent from spontaneous breakdown of relativity,"Spontaneous violation of relativistic invariance of the vacuum can derive
quantum chromodynamics from an U(1) Higgs model including fermions, if the
emergent theory is Lorentz invariant. In this model, the vacuum becomes
anisotropic, and a fermion created on a triplet of spin-one vacua acquires
degeneracy analogous to the color degrees of freedom. The Nambu-Goldstone
bosons originating from the breakdown of rotational symmetry provide the quasi
fermions with SU(3)$\times$U(1) effective interactions, which are interpretable
as mediated by gluons and photons. The confinement of quasi quarks as well as
that of Nambu-Goldstone gluons follow from the Lorentz invariance of the
emergent theory.",1607.05960v1
2016-07-28,General Electromagnetic Nonminimal Couplings in the Dirac Equation,"We examine a new class of CPT-even and dimension-five nonminimal interactions
between fermions and photons, deprived of higher-order derivatives, yielding
electric dipole moment and magnetic dipole moment in the context of the Dirac
equation. These couplings are Lorentz-violating nonminimal structures, composed
of a rank-2 tensor, the electromagnetic tensor, and gamma matrices, being
addressed in its axial and non-axial hermitian versions. We use the electron's
anomalous magnetic and electric dipole moment measurements to reach upper
bounds of $1$ part in $10^{11}$ and $10^{16}$ GeV$^{-1}$.",1607.08546v1
2016-09-27,Improvement of a Theorem of Lorentz (1963) and its Generalization to the Multivariate Case,"In this short note we have proved an enhanced version of a theorem of Lorentz
[1] and its generalization to the multivariate case which gives a non- uniform
estimate of degree of approximation by a polynomial with positive coefficients.
The performance of the approximation at the vertices of [0; 1]d is more
precisely characterized by the improved result and its multivariate
generalization. The latter provides mathematical foundation on which
multivariate density approximation by a polynomial with positive coefficients
can be established.",1610.01448v2
2017-02-13,Interpolation theorem for Marcinkiewicz spaces with applications to Lorentz gamma spaces,"This paper is devoted to the interpolation principle between spaces of weak
type. We characterise interpolation spaces between two Marcinkiewicz spaces in
terms of Hardy type operators involving suprema. We study general properties of
such operators and their behavior on Lorentz gamma spaces. A particular
emphasis is placed on elementary and comprehensive proofs.",1702.03871v2
2017-02-14,Covariant Response Theory and the Boost Transform of the Dielectric Tensor,"After a short critique of the Minkowski formulae for the electromagnetic
constitutive laws in moving media, we argue that in actual fact the problem of
Lorentz-covariant electromagnetic response theory is automatically solved
within the framework of modern microscopic electrodynamics of materials. As an
illustration, we first rederive the well-known relativistic transformation
behavior of the microscopic conductivity tensor. Thereafter, we deduce from
first principles the transformation law of the wavevector- and
frequency-dependent dielectric tensor under Lorentz boost transformations.",1702.06985v3
2017-03-07,Error estimates of the Crank-Nicolson Galerkin method for the time-dependent Maxwell-Schrödinger equations under the Lorentz gauge,"In this paper we study the numerical method and the convergence for solving
the time-dependent Maxwell-Schr\""{o}dinger equations under the Lorentz gauge.
An alternating Crank-Nicolson finite element method for solving the problem is
presented and the optimal error estimate for the numerical algorithm is
obtained by a mathematical inductive method. Numerical examples are then
carried out to confirm the theoretical results.",1703.02274v1
2017-03-15,The Sym2Int program: going from symmetries to interactions,"Model builders often need to find the most general Lagrangian which can be
constructed from a given list of fields. These fields are actually
representations of the Lorentz and gauge groups (and maybe of some discrete
symmetry group as well). I will describe a simple program (Sym2Int) which helps
to automate this task by listing all possible interactions between
Lorentz/gauge group representations.",1703.05221v1
2017-03-20,Enneper representation of minimal surfaces in the three-dimensional Lorentz-Minkowski space,"In this paper, we will give an Enneper-type representation for spacelike and
timelike minimal surfaces in the Lorentz-Minkowski space $L^{3}$, using the
complex and the paracomplex analysis (respectively). Then, we exhibit various
examples of minimal surfaces in $L^{3}$ constructed via the Enneper
representation formula, that it is equivalent to the Weierstrass representation
obtained by Kobayashi (for spacelike immersions) and by Konderak (for the
timelike ones).",1703.06738v1
2018-02-05,Dynamical gauge symmetry breaking in lower-dimensional Lorentz-violating supersymmetric theory,"In this work we study the dynamical generation of mass in the
Lorentz-violating low-dimensional Super-Yang-Mills theory in the aether
superspace coupled to a scalar matter. We also suggest that our studies can be
applied for condensed matter systems, especially lower-dimensional
superconductors and topological insulators. In low dimensional materials, the
parameter $\Delta$ generated by presence of the aether term can be interpreted
as a quantity that renormalizes the propagation velocity of the bosonic mode
with respect to the Fermi velocity.",1802.01368v2
2018-03-30,Relativistic wave equations with extended set of the Lorentz group representations,"It is shown that the use of extended sets of irreducible representations of
the Lorentz group opens new possibilities for the theory of relativistic wave
equations from the point of view of the space-time description of both the
internal structure and the isospin degrees of freedom of elementary particles.
The approach developed in this work also makes it possible to apply the methods
of the theory of relativistic wave equations in superstring and gauge models of
fundamental interactions.",1804.00556v1
2018-04-03,Spreading of relativistic probability densities and Lorentz contraction,"We find the laws for the spreading of the spatial widths (parallel and
transverse to the direction of average motion) of the relativistic position
probability density for a massive, spinless particle. We find that when the
momentum width of the wavepacket is small compared to the average momentum,
there is a long time over which spreading is minimal. This result may be useful
in particle accelerator design. We also demonstrate the Lorentz contraction of
a wavepacket using relativistic probability amplitudes.",1804.00826v1
2018-04-20,Cosmic-ray fermion decay through tau-antitau emission with Lorentz violation,"We study CPT and Lorentz violation in the tau-lepton sector of the Standard
Model in the context of the Standard-Model Extension, described by a
coefficient which is thus far unbounded by experiment. We show that any
non-zero value of this coefficient implies that, for sufficiently large
energies, standard-model fermions become unstable against decay due to the
emission of a pair of tau-antitau leptons. We calculate the induced fermion
energy-loss rate and we deduce the first limit on the Lorentz- and
CPT-violating coefficient.",1804.07586v1
2018-04-29,Translating surfaces of the non-parametric mean curvature flow in Lorentz manifold $M^{2}\times\mathbb{R}$,"In this paper, for the Lorentz manifold $M^{2}\times\mathbb{R}$, with $M^{2}$
a $2$-dimensional complete surface with nonnegative Gaussian curvature, we
investigate its space-like graphs over compact strictly convex domains in
$M^{2}$, which are evolving by the non-parametric mean curvature flow with
prescribed contact angle boundary condition, and show that solutions converge
to ones moving only by translation.",1804.10864v3
2018-11-06,Very Special $T\bar{J}$ deformed CFT,"We study a very special class of $T\bar{J}$ deformations of conformal field
theories in two dimensions. While the deformations break the Lorentz symmetry,
they preserve the twisted Lorentz symmetry. The resulting theory has
right-moving Virasoro as well as left-moving translation and left-moving
(chiral) scale symmetry without left-moving special conformal symmetry (nor
left-moving Virasoro symmetry). As in the original $T\bar{J}$ deformations,
they may be regarded as an operator dependent non-local change of coordinates.
We show concrete examples based on worldsheet string theory and discuss how the
non-unitary nature enables us to circumvent various no-go theorems.",1811.02173v1
2018-11-22,de Sitter-covariant Hamiltonian formalism of Einstein--Cartan gravity,"The Hamiltonian formalism of Einstein--Cartan (EC) gravity is a starting
point for canonical quantum gravity. The existing formalisms are at most
Lorentz covariant, or diffeomorphism covariant. Here we analyze the Hamiltonian
EC gravity in a 5d covariant way, with the gauge group being the de Sitter (dS)
group, which unifies the Lorentz transformations and translation in an elegant
manner, and also coincides with the acceleration of the universe. We
reformulate the EC equations into a dS-covariant form, then find out the
dS-covariant constraints of the phase space, and make all the constraint
functions constitute a closed algebra by constructing a dS-invariant Dirac
bracket, for the purpose of quantization.",1811.09159v2
2018-11-22,Maximal operators and singular integrals on the weighted Lorentz and Morrey spaces,"In this paper, we first give some new characterizations of Muckenhoupt type
weights through establishing the boundedness of maximal operators on the
weighted Lorentz and Morrey spaces. Secondly, we establish the boundedness of
sublinear operators including many interesting in harmonic analysis and its
commutators on the weighted Morrey spaces. Finally, as an application, the
boundedness of strongly singular integral operators and commutators with
symbols in BMO space are also given.",1811.09264v1
2019-04-30,A recipe for conformal blocks,"We describe a prescription for constructing conformal blocks in conformal
field theories in any space-time dimension with arbitrary quantum numbers. Our
procedure reduces the calculation of conformal blocks to constructing certain
group theoretic structures that depend on the quantum numbers of primary
operators. These structures project into irreducible Lorentz representations.
Once the Lorentz quantum numbers are accounted for there are no further
calculations left to do. We compute a multivariable generalization of the Exton
function. This generalized Exton function, together with the group theoretic
structures, can be used to construct conformal blocks for four-point as well as
higher-point correlation functions.",1905.00036v1
2019-05-08,Behavior of torsion functions of spacelike curves in Lorentz-Minkowski space,"In this paper, we introduce the pseudo-torsion functions along spacelike
curves whose curvature vector field has isolated lightlike points in
Lorentz-Minkowski 3-space, and prove the fundamental theorem. Moreover, we
analyze the behavior of the torsion function at such points. As a corollary, we
obtain a necessary and sufficient condition for real analytic spacelike curves
to be planar.",1905.03367v3
2019-05-09,Exploiting the violation of Lorentz symmetry for the planar Hall effect,"The low energy Dirac and Weyl spectra are allowed to violate the Lorentz
symmetry and thereby have a tilted energy dispersion. The tilt in the energy
dispersion induces a Hall voltage in the plane spanned by the electric field
and the tilt velocity. In the presence of a magnetic field the planar Hall
conductivity and resistivity show Shubnikov de Haas oscillations. The
oscillations in the planar Hall effect can become a fingerprint to spot the
anomalous transport in Dirac and Weyl semimetals.",1905.03815v1
2019-05-14,Holographic Dual of Conformal Field Theories with Very Special $T\bar{J}$ Deformations,"Very special $T\bar{J}$ deformations of a conformal field theory are
irrelevant deformations that break the Lorentz symmetry but preserve the
twisted Lorentz symmetry. We construct a holographic description of very
special $T\bar{J}$ deformations. We give a holographic recipe to study the
double trace as well as single trace deformations. The former is obtained from
the change of the boundary condition while the latter is obtained from the
change of the supergravity background.",1905.05353v1
2019-05-16,The dual Z-property for the Lorentz cone,"The Z-property of a linear map with respect to a cone is an extension of the
notion of Z-matrices. In a recent paper of Orlitzky (see Corollary 6.2 in M.
Orlitzky. Positive and $\mathbf{Z}$-operators on closed convex cones, Electron.
J Linear Algebra, 444--458, 2018) the characterisation of cone-complementarity
is given in terms of the dual of the cone of linear maps satisfying the
Z-property. Therefore, it is meaningful to consider the problem of finding the
dual cone of the cone of linear maps which have the Z-property with respect to
a cone. This short note will solve this problem in the particular case when the
Z-property is considered with respect to the Lorentz cone.",1905.06885v1
2019-05-23,Reflections on the covariance of modified teleparallel theories of gravity,"We review the current status of the Lorentz covariance in teleparallel and
modified teleparallel theories of gravity, and discuss the controversial
features of the different approaches. We also revisit the issue of the remnant
Lorentz gauge symmetries in $f(T)$ gravity.",1905.09913v2
2019-05-24,A 3+1 Decomposition of the Minimal Standard-Model Extension Gravitational Sector,"The 3+1 (ADM) formulation of General Relativity is used in, for example,
canonical quantum gravity and numerical relativity. Here we present a 3+1
decomposition of the minimal Standard-Model Extension gravity Lagrangian. By
choosing the leaves of foliation to lie along a timelike vector field we write
the theory in a form which will allow for comparison and matching to other
gravity models.",1905.10414v1
2019-05-24,On the calculation of covariant expressions for Dirac bilinears,"In this article, various approaches to calculate covariant expressions for
the bilinears of Dirac spinors are presented. For this purpose, algebraic
equations defining Dirac spinors are discussed. Following that, a covariant
approach for spacetime parameterization is presented and the equations defining
Dirac spinors are written fully in terms of Lorentz scalars. After presenting
how the tensorial bilinears can be reduced to combinations of scalar bilinears
with appropriate Lorentz structures, a covariant recipe for the calculation of
scalar bilinears is provided.",1905.10470v2
2020-06-13,A Simple Relativity Solution to the Bell Spaceship Paradox,"The Bell Spaceship Paradox has promoted confusion and numerous resolutions
since its first statement in 1959, including resolutions based on relativistic
stress due to Lorentz contractions. The paradox is that two ships, starting
from the same reference frame and subject to the same acceleration, would snap
a string that connected them, even as their separation distance would not
change as measured from the original reference frame. This paper uses a Simple
Relativity approach to resolve the paradox and explain both why the string
snaps, and how to adjust accelerations to avoid snapping the string. In doing
so, an interesting parallel understanding of the Lorentz contraction is
generated. The solution is applied to rotation to address the Ehrenfest paradox
and orbital precession as well.",2007.04186v1
2010-05-18,ZM theory V: Lorentz force equation and the vector potential,"In ZM theory the direction of time has a non-zero projection onto space and
this projection corresponds to the local velocity relative to the observer.
Classical trajectories can be obtained by following the local direction of
time. The relationship of time to space enables the change in momentum over
time to be related to the spatial change in energy and momentum. Previously
Hamilton's equations-of-motion were derived by considering trajectories in one
space and one time dimensions. Here we consider three space and one time
dimension. Without any other assumptions we derive the Lorentz force law of
electromagnetism with relevant definitions of the scalar and vector potentials.",1005.3234v1
2010-05-23,Transitivity in the theory of the Lorentz group and the Stokes -- Mueller formalism in optics,"Group-theoretical analysis of arbitrary polarization devices is performed,
based on the theory of the Lorentz group. In effective ""non-relativistic""
Mueller case, described by 3-dimensional orthogonal matrices, results of the
one polarization measurement determine group theoretical parameters within the
accuracy of an arbitrary numerical variable. There are derived formulas,
defining Muller parameter of the non-relativistic Mueller device uniquely and
in explicit form by by the results of two independent polarization
measurements. Analysis is extended to Lorentzian optical devices, described by
4-dimensional Mueller matrices.",1005.4212v1
2013-08-15,Gauge theory of Lorentz group on the lattice,"The model with the fermions coupled in the non - minimal way to the gauge
theory of Lorentz group is considered. The lattice regularization is suggested.
It is argued that this model may exist in the phase with broken chiral symmetry
and without confinement. We speculate about the possibility that this
construction may serve as an origin of the dynamical electroweak symmetry
breaking.",1308.3406v1
2013-08-26,Ultra-stable cryogenic optical resonators for tests of fundamental physics,"We present the design and first measurement results for an ultra-stable
cryogenically cooled optical sapphire resonator system with a potential
relative frequency stability better than 3x10^-17. This level of oscillator
stability allows for more precise tests of Einstein's theories of relativity
and thus could help to find first hints of ""new physics"". We will give some
details on a projected experiment to test Lorentz invariance that will utilize
these cavities.",1308.5582v1
2014-03-09,The Soccer-Ball Problem,"The idea that Lorentz-symmetry in momentum space could be modified but still
remain observer-independent has received quite some attention in the recent
years. This modified Lorentz-symmetry, which has been argued to arise in Loop
Quantum Gravity, is being used as a phenomenological model to test possibly
observable effects of quantum gravity. The most pressing problem in these
models is the treatment of multi-particle states, known as the 'soccer-ball
problem'. This article briefly reviews the problem and the status of existing
solution attempts.",1403.2080v3
2014-03-10,Induction of the Lorentz-violating effective actions in quantum electrodynamics,"We introduce a Lorentz-symmetry violating extended quantum electrodynamics
(QED) which preserves gauge symmetry. The extended fermionic sector can
radiatively induce an extended effective action which simultaneously displays
the same electromagnetic terms present in the Carroll-Field-Jackiw,
Myers-Pospelov and Aether actions.",1403.2320v2
2014-03-13,Vacuum contribution of photons in the theory with Lorentz and CPT-violating terms,"The photon contribution to the divergences and conformal anomaly in the
theory with Lorentz and CPT-violating terms is evaluated. We calculate one-loop
counterterms coming from the integration over electromagnetic field and check
that they possess local conformal invariance. Furthermore, conformal anomaly
and anomaly-induced effective action are calculated. It turns out that the new
terms do not affect the dynamics of conformal factor in the anomaly-driven
inflation (Starobinsky model) and its extensions. At the same time, one can
expect these terms to affect gravitational wave equation and, in general,
cosmic perturbations.",1403.3152v1
2014-03-19,From scale invariance to Lorentz symmetry,"It is shown that a unitary translationally invariant field theory in (1+1)
dimensions satisfying isotropic scale invariance, standard assumptions about
the spectrum of states and operators and the requirement that signals propagate
with finite velocity possesses an infinite dimensional symmetry given by one or
a product of several copies of conformal algebra. In particular, this implies
presence of one or several Lorentz groups acting on the operator algebra of the
theory.",1403.4742v2
2014-03-21,Three-loop field renormalization for scalar field theory with Lorentz violation,"Applying the counterterm method in minimal subtraction scheme we calculate
the three-loop quantum correction to field anomalous dimension in a
Lorentz-violating O($N$) self-interacting scalar field theory. We compute the
Feynman diagrams using dimensional regularization and $\epsilon$-expansion
techniques. As this approximation corresponds to a three-loop term, to our
knowledge this is the first time in literature in which such a loop level is
attained for a LV theory.",1403.5336v1
2014-03-24,Superdiffusion in the periodic Lorentz gas,"We prove a superdiffusive central limit theorem for the displacement of a
test particle in the periodic Lorentz gas in the limit of large times $t$ and
low scatterer densities (Boltzmann-Grad limit). The normalization factor is
$\sqrt{t\log t}$, where $t$ is measured in units of the mean collision time.
This result holds in any dimension and for a general class of finite-range
scattering potentials. We also establish the corresponding invariance
principle, i.e., the weak convergence of the particle dynamics to Brownian
motion.",1403.6024v2
2016-11-08,Centro-affine invariants and the canonical Lorentz metric on the space of centered ellipses,"We consider smooth plane curves which are convex with respect to the origin.
We describe centro-affine invariants (that is, GL_+(2,R)-invariants), such as
centro-affine curvature and arc length, in terms of the canonical Lorentz
structure on the three dimensional space of all the ellipses centered at zero,
by means of null curves of osculating ellipses. This is the centro-affine
analogue of the approach to conformal invariants of curves in the sphere
introduced by Langevin and O'Hara, using the canonical pseudo Riemannian metric
on the space of circles.",1611.02347v1
2016-11-19,Lorentz transformation from an elementary point of view,"Elementary methods are used to examine some nontrivial mathematical issues
underpinning the Lorentz transformation. Its eigen-system is characterized
through the exponential of a $G$-skew symmetric matrix, underlining its
unconnectedness at one of its extremes (the hyper-singular case). A different
yet equivalent angle is presented through Pauli coding which reveals the
connection between the hyper-singular case and the shear map.",1611.06379v2
2017-01-01,Derivation of the Lorentz transformation without the use of Einstein's second postulate,"Derivation of the Lorentz transformation without the use of Einstein's Second
Postulate is provided along the lines of Ignatowsky, Terletskii, and others.
This is a write-up of the lecture first delivered in PHYS 4202 E&M class during
the Spring semester of 2014 at the University of Georgia. The main motivation
for pursuing this approach was to develop a better understanding of why the
faster-than-light neutrino controversy (OPERA experiment, 2011) was much ado
about nothing.",1701.00270v2
2017-04-16,Lorentz invariant entanglement distribution for the space-based quantum network,"In recent years there has been a great deal of focus on a globe-spanning
quantum network, including linked satellites for applications ranging from
quantum key distribution to distributed sensors and clocks. In many of these
schemes, relativistic transformations may have deleterious effects on the
purity of the distributed entangled pairs. This becomes particularly important
for the application of distributed clocks. In this paper, we have developed a
Lorentz invariant entanglement distribution protocol that completely removes
the effects due to the relative motions of the satellites.",1704.04774v2
2018-05-16,Higher-order one-loop contributions in Lorentz-breaking QED,"We calculate higher-order quantum contributions in different
Lorentz-violating parameters to the gauge sector of the extended QED. As a
result of this one-loop calculation, some terms which do not produce
first-order corrections, contribute with nontrivial gauge-invariant
second-order quantum inductions.",1805.06256v1
2018-05-24,Non-homogeneous persistent random walks and averaged environment for the Lévy-Lorentz gas,"We consider transport properties for a non-homogeneous persistent random
walk, that may be viewed as a mean-field version of the L\'evy-Lorentz gas,
namely a 1-d model characterized by a fat polynomial tail of the distribution
of scatterers' distance, with parameter $\alpha$. By varying the value of
$\alpha$ we have a transition from normal transport to superdiffusion, which we
characterize by appropriate continuum limits.",1805.09889v1
2000-07-10,Nonclassical Lagrangian Dynamics and Potential Maps,"Section 1 refines the theory of harmonic and potential maps. Section 2
defines a generalized Lorentz world-force law and shows that any PDEs system of
order one generates such a law in suitable geometrical structure. In other
words, the solutions of any PDEs system of order one are harmonic or potential
maps, if we use semi-Riemann-Lagrange structures. Section 3 formulates open
problems regarding the geometry of semi-Riemann manifolds $(J^1(T,M), S_1)$,
$(J^2(T,M), S_2)$, and shows that the Lorentz-Udriste world-force law is
equivalent to covariant Hamilton PDEs on $(J^1(T,M), S_1)$.",0007060v1
2000-07-24,Homogeneous Lorentz manifolds with simple isometry group,"Let H be a closed, noncompact subgroup of a simple Lie group G, such that G/H
admits an invariant Lorentz metric. We show that if G = SO(2,n), with n > 2,
then the identity component of H is conjugate to the identity component of
SO(1,n). Also, if G = SO(1,n), with n > 2, then the identity component of H is
conjugate to the identity component of SO(1,n-1).",0007143v1
2008-07-04,Gamma Ray Burst Central Engines,"I review aspects of the theory of long-duration gamma-ray burst (GRB) central
engines. I focus on the requirements of any model; these include the angular
momentum of the progenitor, the power, Lorentz factor, asymmetry, and duration
of the flow, and both the association and the non-association with bright
supernovae. I compare and contrast the collapsar and millisecond proto-magnetar
models in light of these requirements. The ability of the latter model to
produce a flow with Lorentz factor ~100 while simultaneously maintaining a
kinetic luminosity of ~10^50 ergs/s for a timescale of ~10-100 s is emphasized.",0807.0747v1
2008-07-11,DSR as an explanation of cosmological structure,"Deformed special relativity (DSR) is one of the possible realizations of a
varying speed of light (VSL). It deforms the usual quadratic dispersion
relations so that the speed of light becomes energy dependent, with preferred
frames avoided by postulating a non-linear representation of the Lorentz group.
The theory may be used to induce a varying speed of sound capable of generating
(near) scale-invariant density fluctuations, as discussed in a recent Letter.
We identify the non-linear representation of the Lorentz group that leads to
scale-invariance, finding a universal result. We also examine the higher order
field theory that could be set up to represent it.",0807.1854v1
2009-12-01,Renormalization Of High-Energy Lorentz Violating QED,"We study a QED extension that is unitary, CPT invariant and
super-renormalizable, but violates Lorentz symmetry at high energies, and
contains higher-dimension operators (LVQED). Divergent diagrams are only one-
and two-loop. We compute the one-loop renormalizations at high and low energies
and analyse the relation between them. It emerges that the power-like
divergences of the low-energy theory are multiplied by arbitrary constants,
inherited by the high-energy theory, and therefore can be set to zero at no
cost, bypassing the hierarchy problem.",0912.0113v2
2009-12-17,Testing the Lorentz and CPT Symmetry with CMB polarizations and a non-relativistic Maxwell Theory,"We present a model for a system involving a photon gauge field and a scalar
field at quantum criticality in the frame of a Lifthitz-type non-relativistic
Maxwell theory. We will show this model gives rise to Lorentz and CPT violation
which leads to a frequency-dependent rotation of polarization plane of
radiations, and so leaves potential signals on the cosmic microwave background
temperature and polarization anisotropies.",0912.3317v2
2011-11-01,Superluminal neutrinos from Lorentz-violating dimension-5 operators,"We consider Lorentz- and CPT-violating dimension-5 operators to address the
issue of superluminal neutrinos recently pointed out in OPERA experiments. We
assume these operators in the photon and neutrino sectors coupled to
Lorentz-violating backgrounds in a preferred frame defined by a time-like
direction. We show that such operators can produce a curve with OPERA's slope
that fits OPERA, MINOS and supernova SN1987a data.",1111.0093v3
2011-11-01,On the perturbative generation of the higher-derivative Lorentz-breaking terms,"In this paper, we describe the perturbative generation of the
higher-derivative Lorentz-breaking terms for the gauge field, that is, the
Myers-Pospelov term and the higher-derivative Carroll-Field-Jackiw term. These
terms are explicitly calculated in the one-loop approximation and shown to be
finite and ambiguous.",1111.0198v2
2011-11-30,Space-Like Motions of Quantum Zero Mass Neutrinos,"Recent experimental reports of super-luminal velocity neutrinos moving
between Geneva and Gran Sasso in no way contradict the special relativity
considerations of conventional quantum field theory. A neutrino exchanged
between Geneva and Gran Sasso is both virtual and space-like. The Lorentz
invariant space-like distance $L$ and the Lorentz invariant space-like four
momentum transfered $\varpi $ between Geneva and Gran Sasso can be extracted
from experimental data as will be shown in this work.",1111.7181v1
2012-04-11,The spacetime structure of MOND with Tully-Fisher relation and Lorentz invariance violation,"It is believed that the modification of Newtonian dynamics (MOND) is possible
alternate for dark matter hypothesis. Although Bekenstein's TeVeS supplies a
relativistic version of MOND, one may still wish a more concise covariant
formulism of MOND. In this paper, within covariant geometrical framwork, we
present another version of MOND. We show the spacetime structure of MOND with
properties of Tully-Fisher relation and Lorentz invariance violation.",1204.2542v1
2012-04-12,On the assertion that PCT violation implies Lorentz non-invariance,"Out of conviction or expediency, some current research programs take for
granted that ""PCT violation implies violation of Lorentz invariance"". We point
out that this claim is still on somewhat shaky ground. In fact, for many years
there has been no strengthening of the evidence in this direction. However,
using causal perturbation theory, we prove here that when starting with a local
PCT-invariant interaction, PCT symmetry can be maintained in the process of
renormalization.",1204.2654v1
2012-04-25,Relativistic diffusion of particles with a continuous mass spectrum,"We discuss general positivity conditions necessary for a definition of a
relativistic diffusion on the phase space. We show that Lorentz covariant
random vector fields on the forward cone $p^{2}\geq 0$ lead to a definition of
a generator of Lorentz covariant diffusions. We discuss in more detail
diffusions arising from particle dynamics in a random electromagnetic field
approximating the quantum field at finite temperature. We develop statistical
mechanics of a gas of diffusing particles. We discuss viscosity of such a gas
in an expansion in gradients of the fluid velocity.",1204.5593v1
2012-04-25,Derivation and New Interpretation of the Lorentz Transformations and Einstein's Theorem of Velocity Addition,"It is traditionally believed that the Lorentz transformations (LT) and
Einstein's theorem of velocity addition (ETVA), underlying special relativity,
cannot be obtained from non-relativistic (classical) mechanics. In the present
paper it is shown, however, that both the LT and the ETVA are derivable within
the framework of classical kinematics if the speeds of material points are
bounded above by a certain universal limit $c_+$ which can coincide with the
speed of light $c$ in a vacuum.",1204.5740v4
2013-09-04,Interferometry with relativistic electrons,"We propose an experiment to test the influence of Lorentz contraction on the
interference pattern of a beam of electrons. The electron beam is split and
recombined by two pairs of bi-chromatic laser pulses, using a variation of the
Kapitza-Dirac effect. Between the pairs the electrons are accelerated to
relativistic speed. We show that Lorentz contraction of the distance between
two partial beams will then lead to a reduction of fringe visibility. The
connection of the proposal to Bell's spaceship paradox is discussed.",1309.1157v2
2013-09-10,Zero mean curvature surfaces in Lorentz-Minkowski 3-space and 2-dimensional fluid mechanics,"Space-like maximal surfaces and time-like minimal surfaces in
Lorentz-Minkowski3-space are both characterized as zero mean curvature
surfaces. We are interested in the case where the zero mean curvature surface
changes type from space-like to time-like at a given non-degenerate null curve.
We consider this phenomenon and its interesting connection to 2-dimensional
fluid mechanics in this expository article.",1309.2459v1
2014-04-25,Split-Quaternions and the Dirac Equation,"We show that Dirac 4-spinors admit an entirely equivalent formulation in
terms of 2-spinors defined over the split-quaternions. In this formalism, a
Lorentz transformation is represented as a $2 \times 2$ unitary matrix over the
split-quaternions. The corresponding Dirac equation is then derived in terms of
these 2-spinors. In this framework the $SO(3,2; {\bf R})$ symmetry of the
Lorentz invariant scalar $\overline{\psi}\psi$ is manifest.",1405.0187v4
2014-05-17,Peculiar velocities in dynamic spacetimes,"We investigate the asymptotic behavior of peculiar velocities in certain
physically significant time-dependent gravitational fields. Previous studies of
the motion of free test particles have focused on the \emph{collapse scenario},
according to which a double-jet pattern with Lorentz factor $\gamma \to \infty$
develops asymptotically along the direction of complete gravitational collapse.
In the present work, we identify a second \emph{wave scenario}, in which a
single-jet pattern with Lorentz factor $\gamma \to \infty$ develops
asymptotically along the direction of wave propagation. The possibility of a
connection between the two scenarios for the formation of cosmic jets is
critically examined.",1405.4430v2
2014-05-21,Classical kinematics and Finsler structures for nonminimal Lorentz-violating fermions,"In the current paper the Lagrangian of a classical, relativistic point
particle is obtained whose conjugate momentum satisfies the dispersion relation
of a quantum wave packet that is subject to Lorentz violation based on a
particular coefficient of the nonminimal Standard-Model Extension (SME). The
properties of this Lagrangian are analyzed and two corresponding Finsler
structures are obtained. One structure describes a scaled Euclidean geometry,
whereas the other is neither a Riemann nor a Randers or Kropina structure. The
results of the article provide some initial understanding of classical
Lagrangians of the nonminimal SME fermion sector.",1405.5518v2
2015-12-15,Generalized fractional maximal functions in Lorentz spaces,"In this paper we give the complete characterization of the boundedness of the
generalized fractional maximal operator $$
  M_{\phi,\Lambda^{\alpha}(b)}f(x) : = \sup_{Q \ni x} \frac{\|f
\chi_Q\|_{\Lambda^{\alpha}(b)}}{\phi (|Q|)} \qquad (x \in {\mathbb R}^n), $$
between the classical Lorentz spaces $\Lambda^p (v)$ and $\Lambda^q(w)$ for
appropriate functions $\phi$, where $0 < p,\,q < \infty$, $0 < \alpha \le r <
\infty$, $v,w,\,b$ are weight functions on $(0,\infty)$ such that $0 < B(x): =
\int_0^x b < \infty$, $x > 0$, $B \in \Delta_2$ and $B(t) / t^{\alpha / r}$ is
quasi-increasing.",1512.04799v1
2016-05-02,Lorentz invariant relative velocity and relativistic binary collisions,"This article reviews the concept of Lorentz invariant relative velocity that
is often misunderstood or unknown in high energy physics literature. The
properties of the relative velocity allow to formulate the invariant flux and
cross section without recurring to non--physical velocities or any assumption
about the reference frame. Applications such as the luminosity of a collider,
the use as kinematic variable, and the statistical theory of collisions in a
relativistic classical gas are reviewed. It is emphasized how the hyperbolic
properties of the velocity space explain the peculiarities of relativistic
scattering.",1605.00569v2
2016-07-31,Search for CPT and Lorentz-Symmetry Violation in Entangled Neutral Kaons,"The neutral-kaon system constitutes a fantastic and unique laboratory for the
study of CPT symmetry and the basic principles of quantum mechanics, and a
$\phi$-factory represents a unique opportunity to push forward these studies.
The experimental results show no deviation from the expectations of quantum
mechanics and CPT symmetry, while the extreme precision of the measure- ments,
in some cases, reaches the interesting Planck-scale region. At present the
KLOE-2 experiment is collecting data with an upgraded detector with the aim of
significantly improving these kinds of experimental tests.",1608.00241v1
2016-08-03,Modeling the Dispersion and Polarization Content of Gravitational Waves for Tests of General Relativity,"We propose a generic, phenomenological approach to modifying the dispersion
of gravitational waves, independent of corrections to the generation mechanism.
This model-independent approach encapsulates all previously proposed
parametrizations, including Lorentz violation in the Standard-Model Extension,
and provides a roadmap for additional theories. Furthermore, we present a
general approach to include modulations to the gravitational-wave polarization
content. The framework developed here can be implemented in existing data
analysis pipelines for future gravitational-wave observation runs.",1608.01284v1
2016-12-07,Space anisotropy search at colliders,"In the framework of model with Lorentz violation (LV) we discuss a physical
observables for $q\bar{q}$ pair production at lepton-lepton colliders and
describe the experimental signal to be detected. We obtain a conservative
limits on Lorentz-violating dimensionless coupling for quark sector from LEP
data. We also make a phenomenological prediction for LV model at the future
lepton collider.",1612.02217v3
2017-06-04,Lorentz-covariant coordinate-space representation of the leading hadronic contribution to the anomalous magnetic moment of the muon,"We present a Lorentz-covariant, Euclidean coordinate-space expression for the
hadronic vacuum polarisation, the Adler function and the leading hadronic
contribution to the anomalous magnetic moment of the muon. The representation
offers a lot of flexibility for an implementation in lattice QCD. We expect it
to be particularly helpful for the quark-line disconnected contributions.",1706.01139v1
2017-06-05,Constraints on Lorentz symmetry violations with Lunar Laser Ranging,"We present new constraints on Lorentz symmetry (LS) violations with lunar
laser ranging (LLR). Those constraints are derived in the standard-model
extension (SME) framework aiming at parameterizing any LS deviations in all
sectors of physics. We restrict ourself to two sectors namely the pure
gravitational sector of the minimal SME and the gravity-matter coupling. We
describe the adopted method and compare our results to previous analysis based
on theoretical grounds. This work constitutes the first direct experimental
determination of the SME coefficients using LLR measurements.",1706.01243v1
2017-06-28,Lorentz transformation of electromagnetic pulses derived from Hertz potentials,"Electric and magnetic Hertz potentials are a formalism for obtaining
solutions of Maxwell's equations from solutions of the inhomogeneous wave
equation, with polarisation and magnetisation as the sources. We provide an
overview of their covariant transformation properties, and examine an
application of Hertz potentials to the Lorentz transformation of localised
pulses by Lekner, who obtained a result seeming to contradict Von Laue's
theorem. We show that Lekner's result of total energy-momentum not transforming
as a four-vector was due to an erroneous transformation of Hertz potentials,
that did not take into account their bivector nature.",1706.09513v1
2017-07-01,Vector valued maximal Carleson type operators on the weighted Lorentz spaces,"In this paper, by using the idea of linearizing maximal op-erators originated
by Charles Fefferman and the TT* method of Stein-Wainger, we establish a
weighted inequality for vector valued maximal Carleson type operators with
singular kernels proposed by Andersen and John on the weighted Lorentz spaces
with vector-valued functions.",1707.00092v1
2017-10-07,Superpolynomial and polynomial mixing for semiflows and flows,"We give a review of results on superpolynomial decay of correlations, and
polynomial decay of correlations for nonuniformly expanding semiflows and
nonuniformly hyperbolic flows. A self-contained proof is given for semiflows.
Results for flows are stated without proof (the proofs are contained in
separate joint work with Balint and Butterley). Applications include
intermittent solenoidal flows, suspended Henon attractors, Lorenz attractors,
and various Lorentz gas models including the infinite horizon Lorentz gas.",1710.02670v3
2017-12-18,Relativistic effect of entanglement in fermion-fermion scattering,"We study the properties of entanglement entropy among scattering particles as
observed from different inertial moving frames, based on an exemplary QED
process $e^+e^-\rightarrow\mu^+\mu^-$. By the explicit calculation of the
Wigner rotation, the entanglement entropy of scattering particles is found to
be Lorentz invariant. We also study the behavior of the entanglement between
spin degrees of freedom for scattering particles in moving frames. This
quantity, being found to change with different inertial reference frames, does
not exhibit as a Lorentz invariant.",1712.06237v1
2017-12-21,Spontaneous Breaking of (2+1)-dimensional Lorentz Symmetry by an antisymmetric tensor,"One kind of spontaneous (2+1)-dimensional Lorentz symmetry breaking is
discussed. The symmetry breaking pattern is $SO(2,1)\rightarrow SO(1,1)$. Using
the coset construction formalism, we derive the Goldstone covariant derivative
and the associated covariant gauge field. Finally, the two-derivative
low-energy effective action of the Nambu-Goldstone bosons is obtained.",1712.07803v1
2018-01-19,"Scalar-torsion theories of gravity II: $L(T, X, Y, φ)$ theory","We consider Lorentz invariant scalar-tensor teleparallel gravity theories
with a Lagrangian built from the torsion scalar, a scalar field, its kinetic
term and a derivative coupling between the torsion and the scalar field. The
field equations of the theory are derived and the relation between the spin
connection and the antisymmetric part of the tetrad field equations is found
explicitly, which is an important consistency result for Lorentz invariant
teleparallel theories of gravity. Afterwards we study the behaviour of this
class of theories under conformal transformations and find that such
transformations map different theories in this class onto each other.",1801.06536v2
2018-01-31,Embeddings for spaces of Lorentz-Sobolev type,"The purpose of this paper is to characterize all embeddings for versions of
Besov and Triebel-Lizorkin spaces where the underlying Lebesgue space metric is
replaced by a Lorentz space metric. We include two appendices, one on the
relation between classes of endpoint Mikhlin-H\""ormander type Fourier
multipliers, and one on the constant in the triangle inequality for the spaces
$L^{p,r} $ when $p<1$.",1801.10570v2
2018-09-16,Magnetic monopoles in Lorentz-violating electrodynamics,"We investigate the possibility of coexistence between Dirac-like monopoles
and Lorentz-violating electrodynamics. For this purpose, we study three
distinct models: Myers-Pospelov, Ellis et al. and Gambini-Pullin. In
particular, we find that in the Myers-Pospelov electrodynamics, magnetic
sources may be properly induced when it is accompanied by the appearance of an
extra electric current. The symmetry under duality transformations and the
Dirac quantization condition in the aforementioned theories is also discussed.",1809.05783v2
2018-09-17,Lorentz-violating extension of the spin-one Duffin-Kemmer-Petiau equation,"We investigate the breaking of Lorentz symmetry caused by the inclusion of an
external four-vector via a Chern-Simons-like term in the Duffin-Kemmer-Petiau
Lagrangian for massless and massive spin-one fields. The resulting equations of
motion lead to the appearance of birefringence, where the corresponding photons
are split into two propagation modes. We discuss the gauge invariance of the
extended Lagrangian. Throughout the paper, we utilize projection operators to
reduce the wave-functions to their physical components, and we provide many new
properties of these projection operators.",1809.06400v1
2018-09-20,$T\overline T$ deformations of non-Lorentz invariant field theories,"We point out that the arguments of Zamolodchikov and others on the
$T\overline T$ and similar deformations of two-dimensional field theories may
be extended to the more general non-Lorentz invariant case, for example
non-relativistic and Lifshitz-type theories. We derive results for the
finite-size spectrum and $S$-matrix of the deformed theories.",1809.07849v2
2018-09-22,When Fields Are Not Degrees of Freedom,"We show that in the Maxwell-Lorentz theory of classical electrodynamics most
initial values for fields and particles lead to an ill-defined dynamics, as
they exhibit singularities or discontinuities along light-cones. This
phenomenon suggests that the Maxwell equations and the Lorentz force law ought
rather to be read as a system of delay differential equations, that is,
differential equations that relate a function and its derivatives at different
times. This mathematical reformulation, however, leads to physical and
philosophical consequences for the ontological status of the electromagnetic
field. In particular, fields cannot be taken as independent degrees of freedom,
which suggests that one should not add them to the ontology.",1809.08486v1
2018-10-04,Reparameterization Invariant Operator Basis for NRQED and HQET,"We discuss how reparameterization invariance connects a
rotationally-invariant heavy particle effective theory with a single fermion to
a Lorentz-invariant theory. Using Hilbert-series methods, a Lorentz-invariant
operator basis is tabulated, up to and including operators of order $1/M^4$,
when the fermion couples to an external $U(1)$ or $SU(3)$ gauge interaction.",1810.02356v2
2018-10-11,"Relating Noncommutative SO(2,3) Gravity to the Lorentz-Violating Standard-Model Extension","We consider a model of noncommutative gravity that is based on a spacetime
with broken local SO(2,3) symmetry. We show that the torsion-free version of
this model is contained within the framework of the Lorentz-violating
Standard-Model Extension. We analyze in detail the relation between the
torsion-free, quadratic limits of the broken SO(2,3) model and the
Standard-Model Extension. As part of the analysis,we construct the relevant
geometric quantities to quadratic order in the metric perturbation around a
flat background.",1810.05136v1
2019-06-24,Vacuum Cherenkov Radiation for Lorentz-Violating Fermions,"The current article reviews results on vacuum Cherenkov radiation obtained
for modified fermions. Two classes of processes can occur that have completely
distinct characteristics. The first one does not include a spin flip of the
radiating fermion, whereas the second one does. A r\'{e}sum\'{e} will be given
of the decay rates for these processes and their properties.",1906.10152v1
2019-06-28,Conformal Two-Point Correlation Functions from the Operator Product Expansion,"We compute the most general embedding space two-point function in arbitrary
Lorentz representations in the context of the recently introduced formalism in
arXiv:1905.00036 and arXiv:1905.00434. This work provides a first explicit
application of this approach and furnishes a number of checks of the formalism.
We project the general embedding space two-point function to position space and
find a form consistent with conformal covariance. Several concrete examples are
worked out in detail. We also derive constraints on the OPE coefficient
matrices appearing in the two-point function, which allow us to impose
unitarity conditions on the two-point function coefficients for operators in
any Lorentz representations.",1906.12349v1
2019-06-22,Uniqueness of the Isotropic Frame and Usefulness of the Lorentz Transformation,"According to the postulates of the special theory of relativity (STR),
physical quantities such as proper times and Doppler shifts can be obtained
from any inertial frame by regarding it as isotropic. Nonetheless many
inconsistencies arise from the postulates, as shown in this paper. However,
there are numerous experimental results that agree with the predictions of STR.
It is explained why they are accurate despite the inconsistencies. The Lorentz
transformation (LT), unless subject to the postulates of STR, may be a useful
method to approach physics problems. As an example to show the usefulness of
LT, the problem of the generalized Sagnac effect is solved by utilizing it.",1907.00705v1
2019-07-01,Space-like maximal surfaces containing entire null lines in Lorentz-Minkowski 3-space,"Consider a surface $S$ immersed in the Lorentz-Minkowski 3-space $\boldsymbol
R^3_1$. A complete light-like line in $\boldsymbol R^3_1$ is called an entire
null line on the surface $S$ in $\boldsymbol R^3_1$ if it lies on $S$ and
consists of only null points with respect to the induced metric. In this paper,
we show the existence of embedded space-like maximal graphs containing entire
null lines. If such a graph is defined on a convex domain in $\boldsymbol R^2$,
then it must be a light-like plane. Our example is critical in the sense that
it is defined on a certain non-convex domain.",1907.00739v1
2019-07-19,Optimal local embeddings of Besov spaces involving only slowly varying smoothness,"The aim of the paper is to establish (local) optimal embeddings of Besov
spaces $B^{0,b}_{p,r}$ involving only a slowly varying smoothness $b$. In
general, our target spaces are outside of the scale of Lorentz-Karamata spaces
and are related to small Lebesgue spaces. In particular, we improve results
from [CGO11b], where the targets are (local) Lorentz-Karamata spaces. To derive
such results, we apply limiting real interpolation techniques and weighted
Hardy-type inequalities.",1907.08459v1
2019-07-24,Conformal Four-Point Correlation Functions from the Operator Product Expansion,"We show how to compute conformal blocks of operators in arbitrary Lorentz
representations using the formalism described in arXiv:1905.00036 and
arXiv:1905.00434, and present several explicit examples of blocks derived via
this method. The procedure for obtaining the blocks has been reduced to (1)
determining the relevant group theoretic structures and (2) applying
appropriate predetermined substitution rules. The most transparent expressions
for the blocks we find are expressed in terms of specific substitutions on the
Gegenbauer polynomials. In our examples, we study operators which transform as
scalars, symmetric tensors, two-index antisymmetric tensors, as well as mixed
representations of the Lorentz group.",1907.10506v1
2019-09-12,Central limit theorems for the $\mathbb{Z}^2$-periodic Lorentz gas,"This paper is devoted to the study of the stochastic properties of dynamical
systems preserving an infinite measure. More precisely we prove central limit
theorems for Birkhoff sums of observables of $\mathbb{Z}^2$-extensions of
dynamical systems (satisfying some nice spectral properties). The motivation of
our paper is the $\mathbb{Z}^2$-periodic Lorentz process for which we establish
a functional central limit theorem for H\""older continuous observables (in
discrete time as well as in continuous time).",1909.05514v1
2019-09-24,(Gravitational) Vacuum Cherenkov Radiation,"This work reviews our current understanding of Cherenkov-type processes in
vacuum that may occur due to a possible violation of Lorentz invariance. The
description of Lorentz violation is based on the Standard Model Extension
(SME). To get an overview as general as possible, the most important findings
for vacuum Cherenkov radiation in Minkowski spacetime are discussed. After
doing so, special emphasis is put on gravitational Cherenkov radiation. For a
better understanding, the essential properties of the gravitational SME are
recalled in this context. The common grounds and differences of vacuum
Cherenkov radiation in Minkowski spacetime and in the gravity sector are
emphasized.",1909.11045v1
2020-02-04,Lorentz symmetry violation and the tunneling radiation of fermions with spin $1/2$ for Kerr Anti-de-Sitter black hole,"We studied the correction of the quantum tunneling radiation of fermions with
spin $1/2$ in Kerr Anti-de-Sitter black hole. First, the dynamic equation of
spin $1/2$ fermions was corrected using Lorentz's violation theory. Second, the
new expressions of the fermions quantum tunneling rate, the Hawking temperature
of the black hole and the entropy of the black hole were obtained according to
the corrected fermions dynamic equation. At last, some comments are made on the
results of our work.",2002.01148v1
2020-02-20,A pre-metric generalization of the Lorentz transformation,"The concept of an observer and their associated rest space is defined in a
pre-metric (i.e., projective-geometric) context that relates to time+space
decompositions of the tangent bundle to space-time. The transformation from one
observer to another when the two are in a state of relative motion is then
defined, and its relationship to the Lorentz transformation is discussed. The
group of all linear transformations that preserve the observer quadric, which
generalizes the proper-time hyperboloid in Minkowski space, is defined and the
reductions to some of its subgroups are described, as well as its extension to
the group that preserves the fundamental quadric, which generalizes the light
cone.",2002.09500v1
2020-04-01,Gravitational Field on the Lorentz Tangent Bundle: Generalized Paths and Field Equations,"We investigate the dynamics of gravitational field and particles in a
generalized framework of a Lorentz tangent bundle. By variating an appropriate
action for each case, we obtain generalized forms of paths and generalized
field equations for a Sasaki type metric. We show that Stokes theorem is
modified with respect to general relativity due to local anisotropy and the
presence of a nonlinear connection which induces an adapted basis in our space.",2004.00356v2
2020-04-04,Lorentz symmetry violating BTZ black holes in massive gravity,"BTZ black holes provide excellent frameworks for studying theories that are
at the interface of classical and quantum gravity. In this paper we couple the
Riemannian spacetime with the bumblebee field, in the background of massive
gravity, which produces the violation of spontaneous Lorentz symmetry. In this
setup we construct a large family of static vacuum BTZ black hole solutions. We
study the asymptotic behaviour of curvature invariants and show that our
resulting solutions describe asymptotically AdS (2+1)-dimensional BTZ black
holes with negative cosmological constant. For positive cosmological constant
they are de Sitter. Thermodynamics of these black holes is also analysed.",2004.02005v1
2020-04-06,Heinz-type mean curvature estimates in Lorentz-Minkowski space,"We provide a unified description of Heinz-type mean curvature estimates under
an assumption on the gradient bound for space-like graphs and time-like graphs
in the Lorentz-Minkowski space. As a corollary, we give a unified vanishing
theorem of mean curvature for these entire graphs of constant mean curvature.",2004.02528v2
2020-12-01,Non-trivial Minkowski backgrounds in f(T) gravity,"Boosted and rotated tetrad backgrounds for the Minkowski space are studied in
$f(T)$ gravity. We perform Lorentzian perturbations at first order around
non-trivial backgrounds and show that some Lorentz modes can exhibit
non-trivial dynamics and can propagate in time. This remarkable feature gives
evidence of additional mode(s) in the Lorentzian sector which have no precedent
in Lorentz-violating modified gravities, however they can cast doubts onto even
theoretical viability of these models.",2012.00696v3
2020-12-09,Improved Drude-Lorentz dielectric function for gold nanospheres,"There is an ever-increasing body of research in applying the Localized
Surface Plasmon Resonance (LSPR) of gold nanospheres for applications in the
visual part of the electromagnetic spectrum. An important aspect of this work
is the accurate representation of the dielectric function for nanospheres with
diameters less than the mean free path of the conduction electrons in the bulk
material. This paper describes the development of a modified Drude-Lorentz
dielectric functions for bulk gold, and for nanosphere. The models are
validated against previously published experimental work and are shown to be
valid for spheres of diameters of greater than 10 nm.",2012.05090v1
2020-12-16,"A new complemented subspace for the Lorentz sequence spaces, with an application to its lattice of closed ideals","We show that every Lorentz sequence space $d(\textbf{w},p)$ admits a
1-complemented subspace $Y$ distinct from $\ell_p$ and containing no isomorph
of $d(\textbf{w},p)$. In the general case, this is only the second nontrivial
complemented subspace in $d(\textbf{w},p)$ yet known. We also give an explicit
representation of $Y$ in the special case
$\textbf{w}=(n^{-\theta})_{n=1}^\infty$ ($0<\theta<1$) as the $\ell_p$-sum of
finite-dimensional copies of $d(\textbf{w},p)$. As an application, we find a
sixth distinct element in the lattice of closed ideals of
$\mathcal{L}(d(\textbf{w},p))$, of which only five were previously known in the
general case.",2012.08935v1
2020-12-24,On Lorentz-invariant bi-spin-2 theories,"We investigate a Lorentz invariant action which is quadratic in two rank-2
symmetric tensor fields in Minkowski spacetime. We apply a scalar-vector-tensor
decomposition to two tensor fields by virtue of 3-dimensional
rotation-invariance of Minkowski spacetime and classify theories with seven
degrees of freedom based on the Hamiltonian analysis. We find two new theories,
which cannot be mapped from the linearized Hassan-Rosen bigravity. In these
theories, the new mass interactions can be allowed thanks to the transverse
diffeomorphism invariance of action.",2012.13461v1
2021-01-07,Linear Functional Equations and their Solutions in Lorentz Spaces,"Assume that $\Omega\subset \mathbb{R}^k$ is an open set, $V$ is a separable
Banach space over a field $\mathbb K\in\{\mathbb R,\mathbb C\}$ and
$f_1,\ldots,f_N \colon\Omega\to \Omega$, $g_1,\ldots, g_N\colon\Omega\to
\mathbb{K}$, $h_0\colon \Omega\to V$ are given functions. We are interested in
the existence and uniqueness of solutions $\varphi\colon \Omega\to V$ of the
linear functional equation $\varphi=\sum_{k=1}^{N}g_k\cdot(\varphi\circ
f_k)+h_0$ in Lorentz spaces.",2101.02428v1
2021-01-14,A stability result for translating space-like graphs in Lorentz manifolds,"In this paper, we investigate space-like graphs defined over a domain
$\Omega\subset M^{n}$ in the Lorentz manifold $M^{n}\times\mathbb{R}$ with the
metric $-ds^{2}+\sigma$, where $M^{n}$ is a complete Riemannian $n$-manifold
with the metric $\sigma$, $\Omega$ has piecewise smooth boundary, and
$\mathbb{R}$ denotes the Euclidean $1$-space. We can prove an interesting
stability result for translating space-like graphs in $M^{n}\times\mathbb{R}$
under a conformal transformation.",2101.05447v1
2021-01-21,"A sharp gradient estimate and $W^{2,q}$ regularity for the prescribed mean curvature equation in the Lorentz-Minkowski space","We consider the prescribed mean curvature equation for entire spacelike
hypersurfaces in the Lorentz-Minkowski space, namely \begin{equation*}
-\operatorname{div}\left(\displaystyle\frac{\nabla u}{\sqrt{1-|\nabla
u|^2}}\right)= \rho \quad \hbox{in }\mathbb{R}^N, \end{equation*} where $N\geq
3$. We first prove a new gradient estimate for classical solutions with smooth
data $\rho$. As a consequence we obtain that the unique weak solution of the
equation satisfying a homogeneous boundary condition at infinity is locally of
class $W^{2,q}$ and strictly spacelike in $\mathbb{R}^N$, provided that
$\rho\in L^q(\mathbb{R}^N) \cap L^m(\mathbb{R}^N)$ with $q>N$ and
$m\in[1,\frac{2N}{N+2}]$.",2101.08594v2
2021-01-22,Coordinate conditions and field equations for pure composite gravity,"Whenever an alternative theory of gravity is formulated in a background
Minkowski space, the conditions characterizing admissible coordinate systems,
in which the alternative theory of gravity may be applied, play an important
role. We here propose Lorentz covariant coordinate conditions for the composite
theory of pure gravity developed from the Yang-Mills theory based on the
Lorentz group, thereby completing this previously proposed higher derivative
theory of gravity. The physically relevant static isotropic solutions are
determined by various methods, the high-precision predictions of general
relativity are reproduced, and an exact black-hole solution with mildly
singular behavior is found.",2101.09203v1
2012-05-16,Consequences of a condensed matter realization of Lorentz violating QED in Weyl semi-metals,"In Lorentz violating quantum electrodynamics (QED) it is known that a
radiatively induced Chern-Simons term appears in the effective action for the
gauge field, which is finite but undetermined. This ambiguity is shown to be
absent in a condensed matter realization of such a theory in Weyl semi-metals
due to the existence of a full microscopic model from which this effective
theory emerges. Physically observable consequences such as birefringence are
also discussed in this scenario.",1205.3722v3
2012-05-23,Resolution of the Mansuripur Paradox,"The interaction of a magnetic dipole with a point charge leads to an apparent
paradox when analyzed using the 3-vector formulation of the Lorentz force.
Specifically, the dipole is subject to a torque in some frames and not in
others. We show that when analyzed according to the covariant 4-vector
formulation the paradox disappears. The torque that arises in certain frames is
connected to the time-space components of the torque in the rest frame, giving
rise to ""hidden"" momentum.",1205.5451v2
2012-05-31,"Comment on ""Trouble with the Lorentz Law of Force: Incompatibility with Special Relativity and Momentum Conservation""","We present a solution for the apparent paradox regarding an incompatibility
between the Lorentz force law and special relativity presented by Mansuripur
[Phys. Rev. Lett. 108, 193901 (2012)]. A connection between the apparent
paradox and the Abraham-Minkowski debate about the momentum of electromagnetic
waves in material media is also presented.",1205.6858v2
2017-05-04,Lorentz group and mass spectrum of elementary particles,"Mass spectrum of localized states (elementary particles) of single quantum
system is studied in the framework of Heisenberg's scheme. Localized states are
understood as cyclic representations of a group of fundamental symmetry
(Lorentz group) within a Gelfand-Neumark-Segal construction. It is shown that
state masses of lepton (except the neutrino) and hadron sectors of matter
spectrum are proportional to the rest mass of electron with an accuracy of
$0,41\%$.",1705.02227v2
2017-05-07,Least action principle for Lorentz force in dilaton-Maxwell electrodynamics,"The least action principle is established for the dynamics of a test particle
in a dilaton-Maxwell background. These dynamics and background are invariant
under the action of the dilatation transformation; explicit form of the
corresponding generalization of the Lorentz force is established for the
considered model. On a stationary background, we have found the integral of
motion of the energy type. This integral is used to resolve the radial dynamics
of test particles in a spherically symmetric electrostatic background.",1705.03362v1
2017-05-18,Lorentz Covariance of Dirac Electrons in Solids: Dielectric and Diamagnetic Properties,"We study the electrodynamics of Dirac electrons in solids (e.g., bismuth) by
comparing it with quantum electrodynamics (QED). It is shown that Lorentz
covariance associated with the Dirac electrons in solids results in a
remarkable correlation between the dielectric and diamagnetic properties,
leading to a significant enhancement in the permittivity directly linked to the
well-known phenomenon of large diamagnetism.",1705.06474v2
2017-09-13,Equilibration and diffusion for a dynamical Lorentz gas,"We consider a model of a dynamical Lorentz gaz : a single particle is moving
in $\mathbb{R}^d$ through an array of fixed an soft scatterers each possessing
an internal degree of freedom coupled to the particle. Assuming the initial
velocity is sufficiently high and modelling the parameters of the scatterers as
random variables, we describe the evolution of the kinetic energy of the
particle by a Markov chain for which each step corresponds to a collision. We
show that the momentum distribution of the particle approaches a
Maxwell-Boltzmann distribution with effective temperature $T$ such that $k_BT$
corresponds to an average of the scatterers' kinetic energy.",1709.04311v2
2017-09-18,"Characterization of interpolation between Grand, small or classical Lebesgue spaces","In this paper, we show that the interpolation spaces between Grand, small or
classical Lebesgue are so called Lorentz-Zygmund spaces or more generally
$G\Gamma$-spaces. As a direct consequence of our results any Lorentz-Zygmund
space $L^{a,r}({\rm Log}\, L)^\beta$, is an interpolation space in the sense of
Peetre between either two Grand Lebesgue spaces or between two small spaces
provided that $ 1<a<\infty, \beta \not= 0$. The method consists in computing
the so called K-functional of the interpolation space and in identifying the
associated norm.",1709.05892v1
2017-09-20,Oscillating solutions for prescribed mean curvature equations: Euclidean and Lorentz-Minkowski cases,"This paper deals with the prescribed mean curvature equations both in the
Euclidean case and in the Lorentz-Minkowski case in presence of a nonlinearity
$g$ such that $g'(0)>0$. We show the existence of oscillating solutions, namely
with an unbounded sequence of zeros. We show the existence of oscillating
solutions, namely with an unbounded sequence of zeros. Moreover these solutions
are periodic, if $N=1$, while they are radial symmetric and decay to zero at
infinity with their derivatives, if $N\ge 2$.",1709.06980v2
2017-11-22,Low Energy Lorentz Violation in Polymer Quantization Revisited,"In previous work, it had been shown that polymer quantized scalar field
theory predicts that even an inertial observer can experience spontaneous
excitations. This prediction was shown to hold at low energies. However, in
these papers it was assumed that the polymer scale is constant. But it is
possible to relax this condition and obtain a larger class of theories where
the polymer scale is a function of momentum. Does the prediction of low energy
Lorentz violation hold for all of these theories? In this paper we prove that
it does. We also obtain the modified rates of radiation for some of these
theories.",1711.08234v2
2017-11-25,Commutative/Non-Commutative Dualities,"We show that it is in principle possible to construct dualities between
commutative and non-commutative theories in a systematic way. This construction
exploits a generalization of the exact renormalization group equation (ERG). We
apply this to the simple case of the Landau problem and then generalize it to
the free and interacting non-canonical scalar field theory. This constructive
approach offers the advantage of tracking the implementation of the Lorentz
symmetry in the non-commutative dual theory. In principle, it allows for the
construction of completely consistent non-commutative and non-local theories
where the Lorentz symmetry and unitarity are still respected, but may be
implemented in a highly non-trivial and non-local manner.",1711.09236v1
2018-06-01,Closed ideals of operators acting on some families of sequence spaces,"We study the lattice of closed ideals in the algebra of continuous linear
operators acting on $p$th Tandori and $p'$th Ces\`{a}ro sequence spaces,
$1\leqslant p<\infty$, which we show are isomorphic to the classical sequence
spaces $(\oplus_{n=1}^\infty\ell_\infty^n)_p$ and
$(\oplus_{n=1}^\infty\ell_1^n)_{p'}$, respectively. We also show that Tandori
sequence spaces are complemented in certain Lorentz sequence spaces, and that
the lattice of closed ideals for certain other Lorentz and Garling sequence
spaces has infinite cardinality.",1806.00382v3
2018-06-21,On the quantum equivalence of an antisymmetric tensor field with spontaneous Lorentz violation,"We present an explicit proof that a minimal model of rank-2 antisymmetric
field with spontaneous Lorentz violation and a classically equivalent vector
field model are also quantum equivalent, by calculating quantum effective
actions of both theories. We comment on the issues encountered while checking
quantum equivalence in curved spacetime.",1806.08194v3
2018-07-18,Stochastic Emergent Quantum Gravity,"We present a stochastic framework for emergent quantum gravity coupled to
matter. The Hamiltonian constraint in diffeomorphism-invariant theories demands
the identification of a clock relative to which dynamics may be defined, and
other degrees of freedom can play the role of rulers. However, a global system
of clock and rulers is generally not available. We provide evidence that
stochasticity associated with critical points of clock and ruler fields can be
related to the emergence of both a probabilistic description consistent with
ordinary quantum theory, and gravitation described by general relativity at
long distances. We propose a procedure for embedding any Lorentz-invariant
field theory, including the Standard Model and its Lorentz-invariant
extensions, in this framework.",1807.07083v1
2018-12-03,Riemann Zero Mean Curvature Examples in Lorentz-Minkowski Space,"Riemann zero mean curvature examples in the Lorentz-Minkowski space are
surfaces with zero mean curvature foliated by circles contained in parallel
planes. In contrast to the Euclidean case, this family of surfaces presents new
and rich features because of the variety of types of circles. In this paper, we
give a geometric description of these examples when the circles are contained
in spacelike planes and timelike planes.",1812.00589v2
2018-12-08,Covariant constraints of massive gravity in metric formulation,"We propose a simple method for deriving the constraints of the de
Rham-Gabadadze-Tolley model in the metric and the Lagrangian formulation, as
possible as keeping the Lorentz covariance. In our formulation, it is not
necessary to use the Hamilton analysis, the vielbein formulation, nor the
Stuckelberg trick for showing the Boulwer-Deser ghost-freeness. It realizes the
Lorentz covariant expressions of the constraints in a certain parameter region.",1812.03383v1
2018-12-20,Non-commutative Fourier transform for the Lorentz group via the Duflo map,"We defined a non-commutative algebra representation for quantum systems whose
phase space is the cotangent bundle of the Lorentz group, and the
non-commutative Fourier transform ensuring the unitary equivalence with the
standard group representation. Our construction is from first principles in the
sense that all structures are derived from the choice of quantization map for
the classical system, the Duflo quantization map.",1812.08616v1
2019-01-01,Martingale approximations and anisotropic Banach spaces with an application to the time-one map of a Lorentz gas,"In this paper, we show how the Gordin martingale approximation method fits
into the anisotropic Banach space framework. In particular, for the time-one
map of a finite horizon planar periodic Lorentz gas, we prove that Holder
observables satisfy statistical limit laws such as the central limit theorem
and associated invariance principles.",1901.00131v4
2019-01-07,"Energy, Forces, Fields and the Lorentz Force Formula","We apply a simple decomposition to the energy of a moving particle. Based on
this decomposition, we identify the potential and kinetic energies, then use
them to give general definitions of momentum and the various kinds of forces
exerted on the particle by fields, followed by the generalization of Newton's
second law to accomodate these generally defined forces. We show that our
generalization implies the Lorentz force law as well as Lagrange's equation,
along with the usually accepted Lagrangian and the associated velocity
dependent potential of a moving charged particle.",1901.01664v1
2019-02-12,Integrable Lorentz-breaking deformations and RG flows,"We construct the all loop effective action for WZW models perturbed by
current-bilinear terms of the type $J_+J_- $, $J_+J_+ $ and $J_-J_- $, the last
two of which explicitly break Lorentz invariance. For isotropic couplings we
prove integrability. For the case in which only the first two terms are present
we identify a non-perturbative symmetry of the effective action and we compute
the exact beta-functions. These become identically zero outside a bounded
region in the parametric space.",1902.05407v2
2019-02-28,There's more than one way to cancel a regularized Stokeslet,"The Green's functions of Stokes flow are widely used analytical and
computational tools for microscale flows. We adapt a procedure from H.A.
Lorentz for the method of images in Stokes flow to the regularized setting. Our
solutions differ from those previously reported, a surprising result given the
uniqueness theory for elliptic partial differential equations. The discrepancy
originates in the fact that the two version are exact solutions of
inhomogeneous Stokes systems with slightly different forcing on the right-hand
sides. We compare the fluid flows produced by the two methods and conclude that
the Lorentz versions may be advantageous in some settings.",1903.00346v1
2019-03-02,A remark on the Liouville problem for stationary Navier-Stokes equations in Lorentz and Morrey spaces,"The Liouville problem for the stationary Navier-Stokes equations on the whole
space is a challenging open problem who has know several recent contributions.
We prove here some Liouville type theorems for these equations provided the
velocity field belongs to some Lorentz spaces and then in the more general
setting of Morrey spaces. Our theorems correspond to a improvement of some
recent result on this problem and contain some well-known results as a
particular case.",1903.00601v3
2019-03-03,Some regularity results for Lorentz-Finsler spaces,"We prove that for continuous Lorentz-Finsler spaces timelike completeness
implies inextendibility. Furthermore, we prove that under suitable locally
Lipschitz conditions on the Finsler fundamental function the continuous causal
curves that are locally length maximizing (geodesics) have definite causal
character, either lightlike almost everywhere or timelike almost everywhere.
These results generalize previous theorems by Galloway, Ling and Sbierski, and
by Graf and Ling.",1903.00842v2
2019-03-28,Maximal operators on Lorentz spaces in non-doubling setting,"We study mapping properties of the centered Hardy--Littlewood maximal
operator $\mathcal{M}$ acting on Lorentz spaces $L^{p,q}(\mathfrak{X})$ in the
context of certain non-doubling metric measure spaces $\mathfrak{X}$. The
special class of spaces for which these properties are very peculiar is
introduced and many examples are given. In particular, for each $p_0, q_0, r_0
\in (1, \infty)$ with $r_0 \geq q_0$ we construct a space $\mathfrak{X}$ for
which the associated operator $\mathcal{M}$ is bounded from
$L^{p_0,q_0}(\mathfrak{X})$ to $L^{p_0,r}(\mathfrak{X})$ if and only if $r \geq
r_0$.",1903.12013v2
2019-04-02,Force on proton vortices in superfluid neutron stars,"Force on proton vortices in superfluid and superconducting matter of neutron
stars is calculated at vanishing stellar temperature. Both longitudinal
(dissipative) and transverse (Lorentz-type) components of the force are derived
in a coherent way and compared in detail with the corresponding expressions
available in the literature. This allows us to resolve a controversy about the
form of the Lorentz-type force component acting on proton vortices. The
calculated force is a key ingredient in magnetohydrodynamics of superconducting
neutron stars and is important for modeling the evolution of stellar magnetic
field.",1904.01363v1
2019-04-17,"Lorentz-invariant, retrocausal, and deterministic hidden variables","We review several no-go theorems attributed to Gisin and Hardy, Conway and
Kochen purporting the impossibility of Lorentz-invariant deterministic
hidden-variable model for explaining quantum nonlocality. Those theorems claim
that the only known solution to escape the conclusions is either to accept a
preferred reference frame or to abandon the hidden-variable program altogether.
Here we present a different alternative based on a foliation dependent
framework adapted to deterministic hidden variables. We analyse the impact of
such an approach on Bohmian mechanics and show that retrocausation (that is
future influencing the past) necessarily comes out without time-loop paradox.",1904.08134v1
2019-04-30,Bounds on Vacuum-Orthogonal Lorentz and CPT Violation from Radiative Corrections,"Certain forms of Lorentz violation in the photon sector are difficult to
bound directly, since they are ""vacuum orthogonal,"" meaning they do not change
the solutions of the equations of motion in vacuum. However, these very same
terms have a unique tendency to contribute large radiative corrections to
effects in other sectors. Making use of this, we set bounds on four previously
unconstrained $d=5$ photon operators at the $10^{-25}$-$10^{-31}$ GeV$^{-1}$
levels.",1904.13042v2
2019-08-06,Isometric deformations of mixed type surfaces in Lorentz-Minkowski space,"A connected regular surface in Lorentz-Minkowski 3-space is called a mixed
type surface if the spacelike, timelike and lightlike point sets are all
non-empty. Lightlike points on mixed type surfaces may be regarded as singular
points of the induced metrics. In this paper, we introduce the L-Gauss map
around non-degenerate lightlike points, and show the fundamental theorem of
surface theory for mixed type surfaces at non-degenerate lightlike points. As
an application, we prove that a real analytic mixed type surface admits
non-trivial isometric deformations around generic lightlike points.",1908.01967v1
2019-08-13,Non-Abelian aether-like term in four dimensions,"The non-Abelian aether-like Lorentz-breaking term, involving triple and
quartic self-coupling vertices, is generated from the non-Abelian
generalization of the Lorentz-breaking extended QED including only a minimal
spinor-vector interaction. This term is shown explicitly to be finite and
non-ambiguous.",1908.04873v2
2019-08-19,Direct and inverse spin Hall effect: Lorentz force and Zeeman energy,"It is shown that magnetic forces as the Lorentz force, exerted on electric
currents, and the force {\mu}Div(B), exerted on electron spins at rest, account
for both the transverse spin imbalance typical of spin Hall effect and the
transverse charge imbalance associated with pure spin currents (inverse spin
Hall effect). Considering that for stationary currents the laboratory reference
frame and those for which the spin up and spin down carriers are at rest are
inertial systems, one can easily find the forces exerted by the lattice on both
spin sub-bands, as well as the force between sub-bands.",1908.07515v1
2019-08-27,One loop Volkov propagator in the Lorentz class of gauges,"We calculate the ultraviolet divergences in a weak field expansion of the
Volkov propagator. This is done for the full Lorentz class of gauges. The
expected gauge invariance of the vacuum mass shift in each sideband is
recovered. However, the renormalisation of the background induced mass shift is
shown to be gauge dependent. In particular, we show that it vanishes in Landau
gauge. We find that only in that gauge does the vacuum renormalisation remove
all ultraviolet divergences.",1908.10228v2
2019-11-13,Note about the spin connection in general relativity,"In general relativity the fermions are treated from the perspective of the
gauged Lorentz group and by introducing the corresponding gauge fields the spin
connection. This procedure is intimately related to the so-called ""vielbein""
formalism and stems from the general structure that can be associated to a
manifold, the affine connection. In this work we derive the correct spin
connection based only on the general covariance of the theory, on the gauged
Lorentz symmetry and on the known space-time properties of fermion bilinears
generalized to the curved space. Our result coincides exactly with the spin
connection obtain through the tetrad formalism.",1911.05283v2
2019-11-28,Lorentz violation footprints in the spectrum of high-energy cosmic neutrinos: Deformation of the spectrum of superluminal neutrinos from electron-positron pair production in vacuum,"The observation of cosmic neutrinos up to 2 PeV is used to put bounds on the
energy scale of Lorentz invariance violation through the loss of energy due to
the production of $e^+e^-$ pairs in the propagation of superluminal neutrinos.
A model to study this effect, which allows to understand qualitatively the
results of numerical simulations, is presented.",1911.12710v1
2019-12-05,Canonical analysis with no second-class constraints of $BF$ gravity with Immirzi parameter,"In this paper we revisit the canonical analysis of $BF$ gravity with the
Immirzi parameter and a cosmological constant. By examining the constraint on
the $B$ field, we realize that the analysis can be performed in a
Lorentz-covariant fashion while utterly avoiding the introduction of
second-class constraints during the whole process. Finally, we make contact
with the description of the phase space of first-order general relativity in
terms of canonical variables with manifest Lorentz covariance subject to
first-class constraints only recently introduced.",1912.02832v2
2019-12-11,On Orlicz Theory,"In this paper, based on concepts of convex sets and convex functions, we
introduce new concepts of functions, Young functions, strong Young functions
and Orlicz functions by relaxing definitions of functions, Young functions,
strong Young functions, Orlicz functions respectively. We also give concepts of
Orlicz spaces, weak Orlicz spaces, Orlicz Sobolev spaces, weak Orlicz Sobolev
spaces, Orlicz Morrey spaces and weak Orlicz Morrey spaces, Orlicz Lorentz
spaces and weak Orlicz Lorentz spaces. In addition, we consider the implicit
properties based on the effect of an operator on the functions and the spaces",1912.05959v1
2019-12-31,Horava-Lifshitz four-fermion model revisited and dynamical symmetry breaking,"In this paper, we develop studies of the dynamical symmetry breaking in the
Horava-Lifshitz four-fermion model for the specific case $z=3$ and explicitly
demonstrate that for various space-time dimensions, one could arrive at the
theory displaying both dynamical generation of the Lorentz symmetry for the
kinetic term and arising the positively defined potential at the same time. At
the same time, for $D=3$, the Lorentz invariant Chern-Simons term is generated.",1912.13378v1
2020-03-18,An Novel Explicit Method to Solve Linear Dispersive Media for Finite Difference Time Domain Scheme,"A novel explicit method to model Lorentz linear dispersive media with finite
difference method are presented. The method shows an explicit method without
any modification to the Leap-Frogging scheme. The polarizations of the Lorentz
media are convoluted simply in the current density. The numerical results are
shown to be competitive accuracy with a conventional method. The codes used in
the numerical investigation are available on the GitHub
(https://github.com/habe36/Dispersive FDTD).",2003.08081v3
2020-05-07,Lorentz estimates for quasi-linear elliptic double obstacle problems involving a Schrödinger term,"Our goal in this article is to study the global Lorentz estimates for
gradient of weak solutions to $p$-Laplace double obstacle problems involving
the Schr\""odinger term: $-\Delta_p u + \mathbb{V}|u|^{p-2}u$ with bound
constraints $\psi_1 \le u \le \psi_2$ in non-smooth domains. This problem has
its own interest in mathematics, engineering, physics and other branches of
science. Our approach makes a novel connection between the study of
Calder\'on-Zygmund theory for nonlinear Schr\""odinger type equations and
variational inequalities for double obstacle problems.",2005.03281v1
2020-05-12,Lorentz spaces in action on pressureless systems arising from models of collective behavior,"We are concerned with global-in-time existence and uniqueness results for
models of pressureless gases that come up in the description of phenomena in
astrophysics or collective behavior. The initial data are rough: in particular,
the density is only bounded. Our results are based on interpolation and
parabolic maximal regularity, where Lorentz spaces play a key role. We
establish a novel maximal regularity estimate for parabolic systems in
$L_{q,r}(0,T;L_p(\Omega))$ spaces.",2005.05603v2
2020-05-15,Classification of zero mean curvature surfaces of separable type in Lorentz-Minkowski space,"Consider the Lorentz-Minkowski $3$-space $\mathbb{L}^3$ with the metric
$dx^2+dy^2-dz^2$ in canonical coordinates $(x,y,z)$. A surface in
$\mathbb{L}^3$ is said to be separable if satisfies an equation of the form
$f(x)+g(y)+h(z)=0$ for some smooth functions $f$, $g$ and $h$ defined in open
intervals of the real line. In this article we classify all zero mean curvature
surfaces of separable type, providing a method of construction of examples.",2005.07663v1
2020-07-31,On the Lorentz-invariance of the Dyson series in theories with derivative couplings,"We speculate on Dyson series for the $S$-matrix when the interaction depends
on derivatives of the fields. We stick on two particular examples: the scalar
electrodynamics and the renormalised $\phi ^4$ theory. We eventually give
evidence that Lorentz invariance is satisfied and that usual Feynman rules can
be applied to the interaction Lagrangian.",2008.03168v2
2020-08-19,On Lorentz-invariant 2D equations admitting long-lived localized solutions with a nontrivial structure,"The article studies Lorentz-invariant 2D equations with long-lived ($t
\backsim 1000$ ) localized solutions. In the case of three scalar fields
localized solutions with a nontrivial internal structure similar to the hadron
structure are showed. In this case, the solutions of the equations are
analogous to the confinement model by flux tube.",2008.08304v2
2020-09-13,"Comment on: ""Rashba coupling induced by Lorentz symmetry breaking effects"". Ann. Phys. (Berlin) \textbf{526}, 187 (2013)","We analyze the results of a paper on ""the arising of a Rashba-like coupling,
a Zeeman-like term and a Darwin-like term induced by Lorentz symmetry breaking
effects in the non-relativistic quantum dynamics of a spin-1/2 neutral particle
interacting with external fields"". We show that the authors did not obtain the
spectrum of the eigenvalue equation but only one eigenvalue for a specific
relationship between model parameters. In particular, the existence of allowed
cyclotron frequencies conjectured by the authors is a mere artifact of the
truncation condition used to obtain exact solutions to the radial eigenvalue
equation.",2009.07039v1
2020-09-26,Lorentz gradient estimates for a class of elliptic p-Laplacian equations with a Schrödinger term,"We prove in this paper the global Lorentz estimate in term of
fractional-maximal function for gradient of weak solutions to a class of
p-Laplace elliptic equations containing a non-negative Schr\""odinger potential
which belongs to reverse H\""older classes. In particular, this class of
p-Laplace operator includes both degenerate and non-degenerate cases. The
interesting idea is to use an efficient approach based on the level-set
inequality related to the distribution function in harmonic analysis.",2009.12527v1
2020-09-28,"Comment on: ""On the influence of a Coulomb-like potential induced by the Lorentz symmetry breaking effects on the harmonic oscillator''. Eur. Phys. J. Plus (2012) \textbf{127}: 102","We analyze the calculation of bound states for a nonrelativistic spin-half
neutral particle under the influence of a Coulomb-like potential induced by
Lorentz symmetry breaking effects. We show that the truncation condition
proposed by the authors only provides one energy eigenvalue for a particular
model potential and misses all the other bound-state energies. The dependence
of the cyclotron frequency on the quantum numbers is a mere artifact of the
truncation condition that is by no means necessary for the existence of bound
states.",2009.13351v1
2020-10-07,The Manhattan and Lorentz Mirror Models -- A result on the Cylinder with low density of mirrors,"We study the Manhattan and Lorentz Mirror models on an infinite cylinder of
finite even width $n$, with the mirror probability $p$ satisfying $p<Cn^{-1}$,
$C$ a constant. We use the Brauer and Walled Brauer algebras to show that the
maximum height along the cylinder reached by a walker is order $p^{-2}$.",2010.03609v1
2020-10-10,"Comment on: ""On the effects of the Lorentz symmetry violation yielded by a tensor field on the interaction of a scalar particle and a Coulomb-type field"" Ann. Phys. 399 (2018) 117-123","We analyze the eigenvalues and eigenfunctions stemming from a recent study of
the interaction of a scalar particle with a Coulomb potential in the presence
of a background of the violation of the Lorentz symmetry established by a
tensor field. We show, beyond any doubt, that the physical conclusions drawn by
the authors from a truncation of a power series, coming from the application of
the Frobenius method, are meaningless and nonsensical.",2010.04997v1
2020-11-18,Generating a topological anomalous Hall effect in a non-magnetic conductor,"The ordinary Hall effect is driven by the Lorentz force, while its anomalous
counterpart occurs in ferromagnets. Here we show that the Berry curvature
monopole of non-magnetic 2D spin-3/2 holes leads to a novel Hall effect linear
in an applied in-plane magnetic field B_x. There is no Lorentz force hence no
ordinary Hall effect, while all disorder contributions vanish to leading order
in B_x. This intrinsic phenomenon, which we term the anomalous planar Hall
effect (APHE), provides a non-quantized footprint of topological transport
directly accessible in p-type semiconductors.",2011.09481v1
2021-02-16,Extension of Lorentz Reciprocity and Poynting Theorems for Spatially Dispersive Media with Quadrupolar Responses,"We provide a self-consistent extension of the Lorentz reciprocity theorem and
the Poynting theorem for media possessing electric and magnetic dipolar and
quadrupolar responses related to electric and magnetic fields and field
gradients. Using these two theorems, we respectively deduce the conditions of
reciprocity and gainlessness and losslessness that apply to the various tensors
mediating the interactions of these multipole moments and the associated fields
and field gradients. We expect that these conditions will play an essential
role in developing advanced metamaterial modeling techniques that include
quadrupolar and spatially dispersive responses.",2102.08197v2
2021-02-17,Hidden Symmetries in Deformed Very Special Relativity,"We study particle dynamics in a space-time invariant under the $DISIM_b(2)$
group - the deformation of the $ISIM(2)$ symmetry group of very special
relativity. We find that the Lorentz violation leads to the creation of higher
order (hidden) symmetries which are connected to those broken at the space-time
level. Through the perspective of the conserved quantities of the special
relativistic case the Lorentz violation is linked to specific non-commutative
relations in phase-space.",2102.08563v3
2021-03-15,The Lorentz-violating real scalar field at thermal equilibrium,"In this paper we study Lorentz-Violation(LV) effects on the thermodynamics
properties of a real scalar field theory due to the presence of a constant
background tensor field. In particular, we analyse and compute explicitly the
deviations of the internal energy, pressure, and entropy of the system at
thermal equilibrium due to the LV contributions. For the free massless scalar
field we obtain exact results, whereas for the massive case we perform
approximated calculations. Finally, we consider the self interacting $\phi^4$
theory, and perform perturbative expansions in the coupling constant for
obtaining relevant thermodynamics quantities.",2103.08724v1
2021-03-17,Periodic solutions for the Lorentz force equation with singular potentials,"We provide sufficient conditions for the existence of periodic solutions of
the of the Lorentz force equation, which models the motion of a charged
particle under the action of an electromagnetic fields. The basic assumptions
cover relevant models with singularities like Coulomb-like electric potentials
or the magnetic dipole.",2103.09544v1
2021-03-18,Lorentz Quantum Computer,"A theoretical model of computation is proposed based on Lorentz quantum
mechanics. Besides the standard qubits, this model has an additional bit, which
we call hyperbolic bit (or hybit in short). A set of basic logical gates are
constructed and their universality is proved. As an application, a search
algorithm is designed for this computer model and is found to be exponentially
faster than the Grover's search algorithm.",2103.10315v3
2021-04-08,Local Lorentz invariance tests for photons and hadrons at the Gamma Factory,"High-precision tests of local Lorentz invariance, via monitoring of the
sidereal time variation of the photon energies emitted by ultrarelativistic
heavy-ion beams and of the beam momentum, are proposed. This paper includes
descriptions of the physics ideas and the concept for the detector. The
experiment results will allow high-precision tests of LLI via anisotropy of the
maximum attainable speed of a photon and an ion. The projected accuracy for the
asymmetries interpreted in the framework of the anisotropic relativistic
mechanics corresponds to the limit on sidereal time variation of the one-way
maximum attainable speed at the levels between $10^{-14}$ and $10^{-17}$.",2104.03784v1
2021-04-12,On perturbative aspects of a nonminimal Lorentz-violating QED with CPT-odd dimension-5 terms,"We consider the Lorentz-violating extended QED involving all nonminimal
dimension-5 additive CPT-odd terms. For this theory, we investigate the
possibility of generating the Carroll-Field-Jackiw (CFJ) term of the first
order in any of these nonminimal couplings. This term is demonstrated to vanish
in certain regularization schemes. We also study the question of
higher-derivative divergent contributions and demonstrate that they can be
eliminated by considering a given proportionality between the coefficients.",2104.05681v2
2021-04-20,"Going to Lorentz when fractional Sobolev, Gagliardo and Nirenberg estimates fail","In the cases where there is no Sobolev-type or Gagliardo-Nirenberg-type
fractional estimate involving $\lvert u\rvert_{W^{s,p}}$, we establish
alternative estimates where the strong $L^p$ norms are replaced by Lorentz
norms.",2104.09867v2
2021-01-04,Does the Coulomb potential have an algebraic origin?,"It is shown that in case of central potentials, both the fourth component of
Lorentz vector as well as Lorentz scalar in the Dirac Hamiltonian, owing to the
conserved Dirac spin-orbital matrix, there arises Wittens N=2 superalgebra. The
generators of this algebra are constructed and their commutativity with Dirac
Hamiltonian is studied. Under the requirement of in-variance relative to this
super algebra it follows that only Coulomb like potential obeys the
corresponding constraints. This fact allows us to suppose the Wittens
superalgebra as an alternative source for emerging of the Coulomb potential. As
a byproduct, we obtain energy spectrum without solving the Dirac equation, i.e.
by pure algebraically.",2105.02115v1
2021-05-10,Macroscopic transports in a rotational system with an electromagnetic field,"In this work, we explore macroscopic transport phenomena associated with a
rotational system in the presence of an external orthogonal electromagnetic
field. Simply based on the lowest Landau level approximation, we derive
nontrivial expressions for chiral density and various currents consistently by
adopting small angular velocity expansion or Kubo formula. While the generation
of anomalous electric current is due to the pseudo gauge field effect of the
spin-rotation coupling, the chiral density and current can be simply explained
with the help of Lorentz boosts. Finally, Lorentz covariant forms can be
obtained by unifying our results and the magnetovorticity effect.",2105.04122v2
2021-05-10,Effects of a background scalar field induced by the Lorentz symmetry violation on Non Relativistic Quantum Mechanics,"The extension of Standard Model of the Fundamental Particles which consider
the Lorentz Symmetry Violation governed by a background tensor field presented
by Colladay and Kostelecky consider the hypothesis of having a privileged
direction in the space-time. Here we investigated a extension of the
Schr\""odinger Equation inspired on that model taking into account a background
scalar field. We analyze the behavior of this modified Schr\""odinger equation
on a particle trapped in a well and quantum harmonic oscillator.",2105.04644v1
2021-05-19,Lorentz spaces and embeddings induced by almost greedy bases in superreflexive Banach spaces,"The aim of this paper is to show that almost greedy bases induce tighter
embeddings in superreflexive Banach spaces than in general Banach spaces. More
specifically, we show that an almost greedy basis in a superreflexive Banach
space $\mathbb{X}$ induces embeddings that allow squeezing $\mathbb{X}$ between
two superreflexive Lorentz sequence spaces that are close to each other in the
sense that they have the same fundamental function.",2105.09203v1
2021-05-20,Translating solutions for a class of quasilinear parabolic initial boundary value problems in Lorentz-Minkowski plane $\mathbb{R}^{2}_{1}$,"In this paper, we investigate the evolution of spacelike curves in
Lorentz-Minkowski plane $\mathbb{R}^{2}_{1}$ along prescribed geometric flows
(including the classical curve shortening flow or mean curvature flow as a
special case), which correspond to a class of quasilinear parabolic initial
boundary value problems, and can prove that this flow exists for all time.
Moreover, we can also show that the evolving spacelike curves converge to a
spacelike straight line or a spacelike Grim Reaper curve as time tends to
infinity.",2105.09482v1
2021-07-05,Lectures on Celestial Holography,"These notes consist of 3 lectures on celestial holography given at the
Pre-Strings school 2021. We start by reviewing how semiclassically, the
subleading soft graviton theorem implies an enhancement of the Lorentz symmetry
of scattering in four-dimensional asymptotically flat gravity to Virasoro. This
leads to the construction of celestial amplitudes as $\mathcal{S}$-matrices
computed in a basis of boost eigenstates. Both massless and massive asymptotic
states are recast as insertions on the celestial sphere transforming as global
conformal primaries under the Lorentz SL$(2, \mathbb{C})$. We conclude with an
overview of celestial symmetries and the constraints they impose on celestial
scattering.",2107.02075v1
2021-07-18,Towards Sympathetic Laser Cooling and Detection of Single (Anti-)Proton,"Current experimental efforts to test the fundamental CPT symmetry with single
(anti-)protons are progressing at a rapid pace but are hurt by the nonzero
temperature of particles and the difficulty of spin state detection. We
describe a laser-based and quantum logic inspired approach to single
(anti-)proton cooling and state detection.",2107.08435v1
2021-08-03,Effects of linear Central potential induced by Lorentz symmetry breaking on a generalized Klein-Gordon Oscillator,"We investigate the generalized Klein-Gordon oscillator under the Lorentz
symmetry breaking effects where, a linear electric and constant magnetic field
is considered and analyze its effects on the relativistic quantum oscillator.
Furthermore, the behavior of the quantum oscillator in the presence of a
Cornell-type scalar potential is analyzed and the solution of the bound state
is obtained. We see that the analytical solution to the generalized
Klein-Gordon oscillator can be achieved and the angular frequency of the
oscillator depends on the quantum numbers of the system",2108.04668v1
2021-08-16,Endpoint $L^1$ estimates for Hodge systems,"In this paper we give a simple proof of the endpoint Besov-Lorentz estimate
  $$
  \|I_\alpha F\|_{\dot{B}^{0,1}_{d/(d-\alpha),1}(\mathbb{R}^d;\mathbb{R}^k)}
\leq C \|F \|_{L^1(\mathbb{R}^d;\mathbb{R}^k)}
  $$ for all $F \in L^1(\mathbb{R}^d;\mathbb{R}^k)$ which satisfy a first order
cocancelling differential constraint. We show how this implies endpoint
Besov-Lorentz estimates for Hodge systems with $L^1$ data via fractional
integration for exterior derivatives.",2108.06857v1
2021-09-13,Bipartite dimer model: perfect t-embeddings and Lorentz-minimal surfaces,"This is the second paper in the series devoted to the study of the dimer
model on t-embeddings of planar bipartite graphs. We introduce the notion of
perfect t-embeddings and assume that the graphs of the associated origami maps
converge to a Lorentz-minimal surface $\mathrm{S}_\xi$ as $\delta\to 0$. In
this setup we prove (under very mild technical assumptions) that the gradients
of the height correlation functions converge to those of the Gaussian Free
Field defined in the intrinsic metric of the surface $\mathrm{S}_\xi$. We also
formulate several open questions motivated by our work.",2109.06272v1
2021-09-27,The Hochschild Cohomology of Uniform Roe Algebras,"In Rufus Willett's and the authors paper ""Bounded Derivations on Uniform Roe
Algebras"" we showed that all bounded derivations on a uniform Roe algebra
$C^*_u(X)$ associated to a bounded geometry metric space $X$ are inner. This
naturally leads to the question of whether or not the higher dimensional
Hochschild cohomology groups of the uniform Roe algebra vanish also. While we
cannot answer this question completely, we are able to give necessary and
sufficient conditions for the vanishing of $H^n_c(C_u^*(X),C_u^*(X))$. Lastly,
we show that if the norm continuous Hochschild cohomology of a uniform Roe
algebra vanishes in all dimensions then the ultraweak-weak* continuous
Hochschild cohomology of that uniform Roe algebra vanishes also.",2109.13292v1
2021-09-29,Kink networks for scalar fields in dimension 1+1,"We consider a scalar field equation in dimension $1+1$ with a positive
external potential having non-degenerate isolated zeros. We construct weakly
interacting pure multi-solitons, that is solutions converging exponentially in
time to a superposition of Lorentz-transformed kinks, in the case of distinct
velocities. We find that these solutions form a $2K$-dimensional smooth
manifold in the space of solutions, where $K$ is the number of the kinks. We
prove that this manifold is invariant under the transformations corresponding
to the invariances of the equation, that is space-time translations and Lorentz
boosts.",2109.14342v1
2021-10-01,Reacting multi-component fluids -- regular solutions in Lorentz spaces,"The paper deals with analysis of a model of a multi-component fluid admitting
chemical reactions. The flow is considered in the incompressible regime. The
main result shows global existence of regular solutions under assumption of
suitable smallness conditions. In order to control the solutions a special
structure condition on the derivatives of chemical production functions
determining the reactions is required. The existence is shown in a new critical
functional framework of Lorentz spaces of type $L_{p,r}(0,T;L_q)$, which allows
to control the integral $\int_0^\infty \|\nabla u(t)\|_{\infty} dt$.",2110.00270v2
2021-10-05,Emergence of Minkowski-Spacetime by Simple Deterministic Graph Rewriting,"The causal set program as well as the Wolfram physics project leave open the
problem of how a graph that is a (3+1)-dimensional Minkowski-spacetime
according to its simple geodesic distances, could be generated solely from
simple deterministic rules. This paper provides a solution by describing simple
rules that characterize discrete Lorentz boosts between 4D lattice graphs,
which combine further to form Wigner rotations that produce isotropy and lead
to the emergence of the continuous Lorentz group and the (3+1)-dimensional
Minkowski-spacetime. On such graphs, the speed of light, the proper time
interval, as well as the proper length are all shown to be highly accurate.",2110.03388v1
2021-10-19,Geometry of weighted Lorentz-Finsler manifolds II: A splitting theorem,"We show an analogue of the Lorentzian splitting theorem for weighted
Lorentz-Finsler manifolds: If a weighted Berwald spacetime of nonnegative
weighted Ricci curvature satisfies certain completeness and metrizability
conditions and includes a timelike straight line, then it necessarily admits a
one-dimensional family of isometric translations generated by the gradient
vector field of a Busemann function. Moreover, our formulation in terms of the
$\epsilon$-range introduced in our previous work enables us to unify the
previously known splitting theorems for weighted Lorentzian manifolds by Case
and Woolgar-Wylie into a single framework.",2110.10308v2
2021-10-27,The Duality Symmetric String at Two-loops,"The Tseytlin duality symmetric string makes manifest the $O(n,n)$ T-duality
symmetry on the worldsheet at the expense of manifest Lorentz invariance. Here
we consider the two-loop renormalisation of this model in the context of
""cosmological"" spacetimes consisting of an internal $n$-dimensional torus
fibred over a one-dimensional base manifold. The lack of manifest Lorentz
symmetry introduces a range of complexities in momenta loop integrals which we
approach using different methods. Whilst the results do satisfy a number of key
consistency criteria, we find however that the two-loop counter-terms are
incompatible with $O(n,n)$ symmetry and obstruct the renormalisability of the
duality symmetric string.",2110.14481v1
2021-11-02,Curvature estimates for spacelike graphic hypersurfaces in Lorentz-Minkowski space $\mathbb{R}^{n+1}_{1}$,"In this paper, we can obtain curvature estimates for spacelike admissible
graphic hypersurfaces in the $(n+1)$-dimensional Lorentz-Minkowski space
$\mathbb{R}^{n+1}_{1}$, and through which the existence of spacelike admissible
graphic hypersurfaces, with prescribed $2$-th Weingarten curvature and
Dirichlet boundary data, defined over a strictly convex domain in the
hyperbolic plane $\mathscr{H}^{n}(1)\subset\mathbb{R}^{n+1}_{1}$ of center at
origin and radius $1$, can be proven.",2111.01345v1
2021-11-24,Weighted Lorentz spaces: sharp mixed $A_p-A_{\infty}$ estimate for maximal functions,"We prove the sharp mixed $A_{p}-A_{\infty}$ weighted estimate for the
Hardy-Littlewood maximal function in the context of weighted Lorentz spaces,
namely \[ \|M\|_{L^{p,q}(w)} \lesssim_{p,q,n}
[w]^{\frac1p}_{A_p}[\sigma]^{\frac1{\min(p,q)}}_{A_{\infty}}, \] where
$\sigma=w^{\frac{1}{1-p}}$. Our method is rearrangement free and can also be
used to bound similar operators, even in the two-weight setting. We use this to
also obtain new quantitative bounds for the strong maximal operator and for $M$
in a dual setting.",2111.12692v1
2021-12-05,Reflection of light from a uniformly moving mirror,"We developed a formula for the law of reflection of a plane-polarized light
beam from an inclined flat mirror in uniform rectilinear motion by a direct
application of the Huygens-Fresnel principle. Applying the obtained formula and
the postulates of special relativity to describe a specific thought experiment,
we showed that the moving mirror must be contracted along the direction of its
motion by the usual Lorentz factor. The result emphasizes the reality of
Lorentz contraction by showing that the contraction is a direct consequence of
the first and second postulates of special relativity, and not a product of the
process of relativistic measurement of the length.",2112.04471v1
2022-01-12,Quantitative bounds for critically bounded solutions to the three-dimensional Navier-Stokes equations in Lorentz spaces,"In this paper, we prove a quantitative regularity theorem and a blow-up
criterion of classical solutions for the three-dimensional Navier-Stokes
equations. By adapting the strategy developed by Tao in [20], we obtain an
explicit blow-up rate in the setting of critical Lorentz spaces $L^{3,
q_{0}}(\mathbb R^3)$ with $3 \leq q_0 < \infty $. Our results improve the
previous regularity in critical Lebesgue spaces $L^3(\mathbb R^3)$ in [20] and
quantify the qualitative result by Phuc in [16].",2201.04656v2
2022-01-18,Higher derivative asymptotic charges and internal Lorentz symmetries,"In line with a recent proposal for the study of asymptotic gravitational
charges, we investigate higher derivative asymptotic charges. We show that the
higher derivative BMS charges are related to the two-derivative BMS charges.
Significantly, we find that internal Lorentz transformations are relevant in
the higher derivative case in contrast to the two-derivative case. We give a
prescription for their precise definition and derive the associated charges,
finding, again, a relation with two-derivative BMS charges.",2201.07014v4
2022-02-07,Semiclassical magnetotransport including the effects of the Berry curvature and Lorentz force,"In topological semimetals and insulators, negative longitudinal
magnetoresistance and angle-dependent planar Hall effect have been reported
arising from the Berry curvature. Using the Boltzmann transport theory, we
present a closed-form expression for the nonequilibrium distribution function
which includes both the effects of the Berry curvature and Lorentz force. Using
this formulation, we obtain analytical expressions for conductivity and
resistivity tensors in Weyl semimetals demonstrating a non-monotonic field
dependence arising from the competition between the two effects.",2202.02910v2
2022-03-02,Larmor frequency shift from magnetized cylinders with arbitrary orientation distribution,"We present a theoretical framework for the NMR and MRI measured Larmor
frequency in media with magnetized microstructure using the mesoscopic Lorentz
sphere and the principle of coarse graining. We obtain an analytical expression
for infinite cylinders with arbitrary orientation dispersion and show how it
depends on the fiber orientation distribution, measurable using diffusion MRI.
Through simulations, we scrutinize the framework including the effect of the
shape and size of the Lorentz cavity and validate our result for cylinders.",2203.01191v3
2022-03-06,Null hypersurfaces as wave fronts in Lorentz-Minkowski space,"In this paper, we show that ""L-complete null hypersurfaces"" (i.e. ruled
hypersurfaces foliated by entirety of light-like lines) as wave fronts in the
$(n+1)$-dimensional Lorentz-Minkowski space $\boldsymbol{R}^{n+1}_1$ are
canonically induced by hypersurfaces in the $n$-dimensional Euclidean space
$\boldsymbol{R}^n_0$. As an application, we show that most of null wave fronts
can be realized as restrictions of certain L-complete null wave fronts.
Moreover, we determine light-like complete null hypersurfaces whose singular
sets are compact.",2203.02864v2
2022-03-07,Electromagnetic Energy Density in Hyperbolic Metamaterials,"We derive the energy density associated with an electromagnetic wave passing
through a hyperbolic metamaterial (HMM). Both types of HMMs are studied. By
considering a dispersive and absorbing HMM as an effective uniaxial crystal, we
find that under the influence of an electromagnetic wave, the response of type
I (type II) HMM in the directions perpendicular to and parallel to the optical
axis are similar to those of Lorentz (Drude) and Drude (Lorentz) media,
respectively. Numerical examples are presented to reveal the general
characteristics of the direction-dependent energy storage capacity of both
types of HMMs.",2203.03146v1
2022-03-14,Aperiodic and linearly repetitive Lorentz gases of finite horizon are not exponentially mixing,"We prove that aperiodic and linearly repetitive Lorentz gases with finite
horizon are not mixing with exponential or stretched exponential speed in any
dimension for any class of H\""older observables. We also bound the polynomial
speed of mixing for observables in the H\""older space $H_{\alpha}$ depending on
$\alpha$.",2203.07215v3
2022-03-17,Spacelike Foliations on Lorentz manifolds,"In this work, we study the geometric properties of spacelike foliations by
hypersurfaces on a Lorentz manifold. We investigate conditions for the leaves
being stable, totally geodesic or totally umbilical. We consider that
$\overline{M}^{n+1}$ is equipped with a timelike closed conformal vector field
$\xi$. If the foliation has constant mean curvature, we show that the leaves
are stable. When the leaves are compact spacelike hypersurfaces we show that,
under certain conditions, its are totally umbilic hypersurfaces. In the case of
foliations by complete noncompact hypersurfaces, we using a Maximum Principle
at infinity to conclude that the foliation is totally geodesic.",2203.09605v1
2022-01-29,Lorentz and gauge invariance of quantum space,"Motivated by generalized uncertainty principle, we derive a discrete picture
of the space that respects Lorentz symmetry as well as gauge symmetry through
setting an equivalency between linear GUP correction term and electromagnetic
interaction term in Dirac equation. We derived a wavefunction solution that
satisfies this equivalency. This discreteness may explain the crystal and
quasicrystal structures observed in nature at different energy scales.",2203.11699v2
2022-04-16,Noncommutative spaces and superspaces from Snyder and Yang type models,"The relativistic $D=4$ Snyder model is formulated in terms of $D=4$ $dS$
algebra $o(4,1)$ generators, with noncommutative Lorentz-invariant Snyder
quantum space-time provided by $\frac{O(4,1)}{O(3,1)}$ coset generators.
Analogously, in relativistic $D=4$ Yang models the quantum-deformed
relativistic phase space is described by the algebras of coset generators
$\frac{O(5,1)}{O(3,1)}$ or $\frac{O(4,2)}{O(3,1)}$. We extend these algebraic
considerations by using respective $dS$ superalgebras, which provide
Lorentz-covariant quantum superspaces (SUSY Snyder model) as well as
relativistic quantum phase super spaces (SUSY Yang model).",2204.07787v1
2022-05-12,$\mathcal{N}=2$ resonant superalgebra for supergravity,"We present new superalgebra for $\mathcal{N}=2$ $D=3,4$ supergravity theory
endowed with the $U(1)$ generator. The superalgebra is rooted in the so-called
Soroka-Soroka algebra and spanned by the Lorentz $J_{ab}$ and Lorentz-like
$Z_{ab}$, translation $P_a$ and $T$ generators, as well as two supercharges
$Q^I_\alpha$. It is the only possible realization for a given generator
content. We construct a corresponding 3D Chern-Simons supergravity realization
of the superalgebra and discuss its relevance.",2205.05921v2
2022-05-26,The phonon Hall viscosity of ionic crystals,"When time-reversal symmetry is broken, the low-energy description of acoustic
lattice dynamics allows for a dissipationless component of the viscosity
tensor, the phonon Hall viscosity, which captures how phonon chirality grows
with the wavevector. In this work, we show that, in ionic crystals, a phonon
Hall viscosity contribution is produced by the Lorentz forces on moving ions.
We calculate typical values of the Lorentz force contribution to the Hall
viscosity using a simple square lattice toy model, and we compare it with
literature estimates of the strengths of other Hall-viscosity mechanisms.",2205.13666v1
2022-06-15,Lorentz-violation-induced arrival time delay of astroparticles in Finsler spacetime,"Finsler geometry is a natural and fundamental generalization of Riemann
geometry. The Finsler structure depends on both coordinates and velocities. We
present the arrival time delay of astroparticles subject to Lorentz violation
in the framework of Finsler geometry, and the result corresponds to that
derived by Jacob and Piran in the standard model of cosmology.",2206.07616v2
2022-06-21,Convex subsets of non-convex Lorentz balls,"Many star bodies have convex subsets with approximately the same Gaussian
measure (of the complement). Inspired by this phenomenon, and in connection
with the randomized Dvoretzky theorem for Lorentz spaces, we derive bounds on
the distribution of certain functions of a Gaussian random vector by
approximating their sub-level sets by convex subsets.",2206.10496v1
2022-06-24,Gravitational memory effects and higher derivative actions,"We show that charges associated with the internal Lorentz symmetries of
general relativity, with higher derivative boundary terms included in the
action, capture observable gravitational wave effects. In particular, the
Gauss-Bonnet charge measures the precession rate of a freely-falling gyroscope,
while the Pontryagin charge encodes the relative radial acceleration of
freely-falling test masses. This relation highlights the importance of the
tetrad formalism and the physical significance of asymptotic internal Lorentz
symmetries.",2206.12339v3
2022-07-22,Axion-Photon Interaction from Nonminimal Dimension-5 Lorentz-Violating Operators,"In this paper, we discuss various possible schemes for the perturbative
generation of the axion-photon interaction term in different Lorentz-breaking
extensions of QED, involving operators with mass dimensions up to 5. We
demonstrate explicitly that there are only a few schemes allowing to generate a
finite axion-photon interaction term from one-loop radiative corrections, and
within all these schemes, the generated term turns out to be ambiguous.",2207.11078v2
2022-08-18,Existence of convolution maximizers in $L_p(R^n)$ for kernels from Lorentz spaces,"The paper extends an earlier result of G.V.~Kalachev and the author (Sb.
Math. 2019 or arXiv:1712.08836) on the existence of a maximizer of convolution
operator acting between two Lebesgue spaces on $R^n$ with kernel from some
$L_q$, $1<q<\infty$. In view of Lieb's result of 1983 about the existence of an
extremizer for the Hardy-Littlewood-Sobolev inequality it is natural to ask
whether a convolution maximizer exists for any kernel from weak $L_q$. The
answer in the negative was given by Lieb in the above citation. In this paper
we prove the existence of maximizers for kernels from a slightly more narrow
class than weak $L_q$, which contains all Lorentz spaces $L_{q,s}$ with $q\leq
s<\infty$.",2208.08783v1
2022-07-06,Surfaces of coordinate finite type in the Lorentz-Minkowski 3-space,"In this article, we study the class of surfaces of revolution in the
3-dimensional Lorentz-Minkowski space with nonvanishing Gauss curvature whose
position vector x satisfies the condition {\Delta}IIIx = Ax, where A is a
square matrix of order 3 and {\Delta}III denotes the Laplace operator of the
second fundamental form III of the surface. We show that such surfaces are
either minimal or pseudospheres of a real or imaginary radius.",2208.12578v1
2022-09-01,Kasner cosmology in bumblebee gravity,"Kasner cosmology is a vacuum and anisotropically expanding spacetime in the
general relativity context. In this work, such a cosmological model is studied
in another context, the bumblebee model, where the Lorentz symmetry is
spontaneously broken. By using the bumblebee context it is possible to justify
the anisotropic feature of the Kasner cosmology. Thus, the origin of the
anisotropy in this cosmological model could be in the Lorentz symmetry
breaking. Lastly, an application in the pre-inflationary cosmology is
suggested.",2209.00589v2
2022-10-05,Lorentz-Finsler metrics on symplectic and contact transformation groups,"In these notes we discuss Lorentz-Finsler metrics, a notion originated in
relativity theory, on certain groups of symplectic and contact transformations.
Some basic geometric questions arising in this context concerning distance,
geodesics and their conjugate points, and existence of a time function, turn
out to be related to a variety of subjects including the contact systolic
problem, group quasi-morphisms, the Monge-Amp\`ere equation, and a subtle
interplay between symplectic rigidity and flexibility. We discuss these
interrelations, providing necessary preliminaries, and formulate a number of
open questions.",2210.02387v1
2022-10-12,Chirality in an $E_8$ model of elementary particles,"We show how chirality emerges naturally from an embedding of the standard
model of particle physics into $E_{8(-24)}$. The well-known argument that there
is no chiral theory of fundamental physics in $E_8$ is avoided by implementing
chirality not as a property of the complexified Lorentz group, but as a
property of the complex representations of the real Lorentz group, combined
with a real scalar. This avoids the problems of complexification, and ensures
that the model is completely contained in the real Lie group.",2210.06029v1
2022-10-20,On homogeneous 3-dimensional spacetimes: focus on plane waves,"We revisit the classification of Lorentz homogeneous spaces of dimension 3,
fixing statements in the literature and relaxing usual completeness
assumptions. In particular, non-unimodular elliptic plane waves, and only them,
are neither locally symmetric nor locally isometric to a left invariant Lorentz
metric on a 3-dimensional Lie group. We characterize homogeneous plane waves in
dimension 3, and prove they are non-extendable, and geodesically complete only
if they are symmetric. Finally, only one non-flat plane wave has a compact
model.",2210.11439v3
2022-11-10,Harnack inequality and asymptotic lower bounds for the relativistic Fokker-Planck operator,"We consider a class of second order degenerate kinetic operators
$\mathscr{L}$ in the framework of special relativity. We first describe
$\mathscr{L}$ as an H\""ormander operator which is invariant with respect to
Lorentz transformations. Then we prove a Lorentz-invariant Harnack type
inequality, and we derive accurate asymptotic lower bounds for positive
solutions to $\mathscr{L} f = 0$. As a consequence we obtain a lower bound for
the density of the relativistic stochastic process associated to $\mathscr{L}$.",2211.05736v1
2022-11-14,Relating quasi-stationary one zone emission models to expanding relativistic shocks,"For an expanding spherical relativistic shock, we derive relations between
the parameters of downstream emitting zone and the quantities measured by a
distant observer. These relations are formulated in terms of dimensionless
effective coefficients combined with self-evident dimensional estimates. Our
calculations take into account evolution of the shock's Lorentz factor,
geometrical delay due to the shock's front curvature, and angular dependence of
Lorentz boost for frequency and brightness. The relations are designed
primarily for application in Gamma-Ray Burst afterglow studies, although they
may have a broader use.",2211.07405v1
2022-11-21,Conserved Currents for the Gauge-Field Theory with Lorentz Symmetry Group,"For the Yang-Mills-type gauge-field theory with Lorentz symmetry group, we
propose and verify an explicit expression for the conserved currents in terms
of the energy-momentum tensor. A crucial ingredient is the assumption that the
gauge symmetry arises from the decomposition of a metric in terms of tetrad
variables. The currents exist under the weak condition that the energy-momentum
tensor and the Ricci tensor commute. We show how the conserved currents can be
used to obtain a composite theory of gravity and discuss the static isotropic
field around a point mass at rest.",2211.11823v1
2022-12-05,A Revisit to Lorentz Transformation without Light,"We derive rotation free Lorentz Transformation (LT) between two inertial
reference frames without using the second postulate of Einstein, i.e., we do
not assume the invariant speed of light (in vacuum) under LT. We find a general
transformation rule between two inertial frames where a speed, invariant under
that transformation, arises naturally. This idea first came into light by
Mathematician Ignatowski [1] around the year, 1910. Without loss of novelty,
here we present our derivation while reviewing more recent literature in this
subject.",2212.03706v1
2022-12-26,"In-beam hyperfine spectroscopy of antihydrogen, hydrogen and deuterium","The ASACUSA collaboration is developing a polarized beam of antihydrogen
atoms to precisely determine the ground-state hyperfine structure for studies
of CPT and Lorentz invariance. Using a beam of ordinary hydrogen, measurements
of both the $\sigma$ and $\pi$-transition have been performed, investigating
orientation-dependent SME coefficients. Furthermore a first hyperfine
experiment with a beam of deuterium is being prepared.",2212.13083v1
2022-12-16,Dual Spacetime Symmetry Breaking down to Einstein Gravity,"Einstein action of gravity is obtained from a gauge theory, if our spacetime
was once in two folds with a double Lorentz symmetry. After the dual symmetry
breaks spontaneously, Lorentz symmetry absorbs gauge symmetry, while the gauge
field begins to drive the vierbein and the spin connection. This gauge model of
gravity has many bosons and fermions with negative norms, which will be
undetectable. The consistency of these particles with the Copenhagen
interpretation of wave functions, and their relation to the presence of dark
matter as well as the absence of antimatter in the universe are discussed.",2212.13131v1
2023-01-02,Unconditional uniqueness and non-uniqueness for Hardy-Hénon parabolic equations,"We study the problems of uniqueness for Hardy-H\'enon parabolic equations,
which are semilinear heat equations with the singular potential (Hardy type) or
the increasing potential (H\'enon type) in the nonlinear term. To deal with the
Hardy-H\'enon type nonlinearities, we employ weighted Lorentz spaces as
solution spaces. We prove unconditional uniqueness and non-uniqueness, and we
establish uniqueness criterion for Hardy-H\'enon parabolic equations in the
weighted Lorentz spaces. The results extend the previous works on the Fujita
equation and Hardy equations in Lebesgue spaces.",2301.00506v3
2023-01-18,Violation of Lorentz symmetries and thermal effects in Compton scattering,"In this paper, the differential cross section for the Compton scattering
process is calculated. Two types of corrections are investigated: corrections
due to violation of Lorentz symmetry and thermal effects. An extended QED is
considered to introduce the parameter that leads to the breaking of symmetry.
While temperature effects are introduced using Thermofield Dynamics formalism.
It is shown that the differential cross section changes with both corrections.
These corrections are dominant at appropriate limits. These special cases are
analyzed and compared with other results from the literature.",2301.07545v1
2023-01-18,The electromagnetic self-force of a Lorentz-contractible spherical shell of radius $R$ in rectilinear arbitrary motion: the terms of order $1/R$ and $R^0$,"We write the electromagnetic self-force of a Lorentz-contractible spherical
shell of radius $R$ in arbitrary rectilinear motion as a series expansion in
powers of $R$, and calculate the first two terms of this series. The method we
use, which is based on the description of the particle in terms of a
velocity-dependent volume charge density, avoids some important difficulties of
the previous approaches from the literature. We compare our results with the
results obtained by other authors. The whole calculation is done in the
laboratory frame of reference.",2301.08223v3
2023-01-20,A Hamiltonian and geometric formulation of general Vlasov-Maxwell-type models,"Three geometric formulations of the Hamiltonian structure of the macroscopic
Maxwell equations are given: one in terms of the double de Rham complex, one in
terms of L2 duality, and one utilizing an abstract notion of duality. The final
of these is used to express the geometric and Hamiltonian structure of kinetic
theories in general media. The Poisson bracket so stated is explicitly metric
free. Finally, as a special case, the Lorentz covariance of such kinetic
theories is investigated. We obtain a Lorentz covariant kinetic theory coupled
to nonlinear electrodynamics such as Born-Infeld or Euler-Heisenberg
electrodynamics.",2301.08812v2
2023-01-21,Phonon-mediated dark to bright plasmon conversion,"The optical response of a matter excitation embedded in nanophotonic devices
is commonly described by the Drude-Lorentz model. Here, we demonstrate that
this widely used approach fails in the case where quantum-confined plasmons of
a two-dimensional electron gas interact strongly with optical phonons. We
propose a new quantum model which contains the semiclassical Drude-Lorentz one
for simple electronic potentials, but predicts very different results in
symmetry-broken potentials. We unveil a new mechanism for the oscillator
strength transfer between bright phonon-polariton and dark plasmon modes,
enabling thus new quantum degrees of freedom for designing the optical response
of nanostructures.",2301.08935v1
2023-01-30,New Developments in the Hamiltonian Formulation of the Gravitational Standard-Model Extension,"This chapter of the proceedings for the Ninth Meeting on CPT and Lorentz
Symmetry is dedicated to the Hamiltonian formulation of the minimal
gravitational Standard-Model Extension. Some theoretical questions associated
with the latter shall be reviewed. First, we recall the properties of the
Hamiltonian, which was computed elsewhere, and discuss how it is linked to the
modified Einstein equations. Second, we describe how the covariant and
Hamiltonian formulations are shown to be consistent with each other.",2301.13008v1
2023-02-27,The geometrical meaning of the Weitzenböck connection,"In the current literature, there are many discussions about the local Lorentz
invariance of modified teleparallel gravity. This symmetry is obviously
violated in the classical ""pure tetrad"" formulation of the theory, while it
gets restored in the ""fully covariant"" approach. My claim is that, despite many
heated discussions, the two formulations are just equivalent. And the purpose
of this note is to argue that the local Lorentz invariance is not natural for
the modified teleparallel theories at all, making the pure tetrad approach more
fundamentally justified.",2302.13599v2
2023-04-04,Study of Einstein Equivalence Principle with Sagnac Effect in Lorentz and Galilean Frame,"Sagnac effect has been studied in terms of Gyroscopic system in both Lorentz
frame as well as flat Einstein frame. The Einstein equivalence principle has
been used to determine the phase shift due to pseudo force in the
transformation from rotating earth frame to stationary frame. A polychromatic
broadband source has been considered for the discussion. The
Langevin-Landau-Lifschitz metric has been used during the incorporation of
General theory of relativity. The square type sagnac interferometer has been
used in theory establishment.",2304.02021v1
2023-04-06,"Symmetric Lorentz-Minkowski, Antisymmetric Dirac-Majorana","We show a nice symmetric/antisymmetric relation between the four vector
Lorentz transformation and the Dirac spinor one in the Majorana representation.
From the spinor one, we exhibit the antisymmetric pending of the symmetric
Minkowski metric. We then rewrite the Dirac equation in various ways exploiting
group properties induced by these relations, and this without complex numbers.
We show also a nice relation with a five dimensional metric. When done, we will
see that the traditional complex electromagnetic coupling could be handled also
without complex numbers by just considering two coupled real fields instead of
one complex field. Finally, we will show that going toward six or ten
dimensional spacetime would be more natural from a group point of view.",2304.03701v1
2023-04-16,Momentum map for the Maxwell-Lorentz equations with spinning particle,"We develop the theory of momentum map for the Maxwell-Lorentz equations with
spinning extended charged particle. This theory is indispensable for the study
of long-time behaviour and radiation of the solitons of this system. The
development relies on the Hamilton-Poisson structure of the system. As an
example, we apply the theory to the rotation group of symmetry, calculating the
expression for the conserved angular momentum. We check the coincidence of this
expression with known classical invariant.",2304.07739v1
2023-05-03,Some problem with the Lorentz transformations of energy and momentum of the electromagnetic field,"In this work, it is shown that the energy and momentum of electromagnetic
fields created by a classical charge, whose velocity varies with time, do not
form four-vector. A possible explanation for this result is that the
calculation of energy and momentum is performed as an integration of the
densities of these quantities, {\it i.e.} the squares of the electromagnetic
field $E^2$ and $H^2$ in the whole space at the hyperplane $t=const$. But $E^2$
and $H^2$, which are calculated at a fixed point in time, $t$, are all created
at previous (retarded) instants of time. In other words, all densities $E^2$
and $H^2$ are independent of each other. Meanwhile, Lorentz transformations are
defined as transformations between physically connected quantities.",2305.01994v1
2023-05-22,Scale anomaly in a Lorentz and CPT-violating Quantum Electrodynamics,"We compute the classical and the quantum breaking of the dilatation current
in the minimal Lorentz and CPT-violating quantum electrodynamics. At the
classical level, scale symmetry is broken by the general mass term
\bar{\psi}M\psi and the Chern-Simons-like term. At the quantum level, it is
broken by all expected observable fermion operators in the massless limit.",2305.12610v1
2023-05-24,Lorentz Reciprocal Theorem in Fluids with Odd Viscosity,"The Lorentz reciprocal theorem -- that is used to study various transport
phenomena in hydrodynamics -- is violated in chiral active fluids that feature
odd viscosity with broken time-reversal and parity symmetries. Here we show
that the theorem can be generalized to fluids with odd viscosity by choosing an
auxiliary problem with the opposite sign of the odd viscosity. We demonstrate
the application of the theorem to two categories of microswimmers. Swimmers
with prescribed surface velocity are not affected by odd viscosity, while those
with prescribed active forces are. In particular, a torque-dipole can lead to
directed motion.",2305.15379v2
2023-06-06,Brownian fluctuations of kinetic energy under Lorentz force,"In stochastic thermodynamics, significant attention has been given to
studying the statistical behavior of thermodynamic quantities such as heat and
work. However, fluctuations in other quantities, such as kinetic energy and
internal energy, can also exhibit intriguing statistical properties. In this
study, we investigate the fluctuations of kinetic energy within an initially
equilibrated underdamped Brownian particle subsequently exposed to a Lorentz
force, comprising both electric and magnetic fields. Providing insights through
the examination of the characteristic function, central moments, and kinetic
energy distribution.",2306.03344v3
2023-06-06,Aether field coupled to the electromagnetic field in the TFD formalism,"In this paper, the aether field, which leads to the violation of Lorentz
symmetries, coupled with the electromagnetic field is considered. In order to
study thermal and size effects in this theory, the Thermo Field Dynamics (TFD)
formalism is used. TFD is a real-time quantum field theory that has an
interesting topological structure. Here three different topologies are taken,
then three different phenomena are calculated. These effects are investigated
considering that the aether field can point in different directions. The
results obtained are compared with the usual results of the Lorentz invariant
electromagnetic field.",2306.03876v1
2023-08-05,On perturbative aspects of a nonminimal Lorentz-violating QED with CPT-even dimension-5 terms,"In this paper, we explicitly calculate the lower CPT-even one-loop quantum
corrections in nonminimal Lorentz-violating spinor QED with all possible
CPT-even dimension-5 operators. Within our calculations, we restrict ourselves
to the cases when these parameters are completely expressed in terms of one
constant vector.",2308.02876v2
2023-08-07,Nine Lorentz covariant bitensors for two Dirac spinors to indicate all entangled states,"The spinorial degrees of freedom of two spacelike separated Dirac particles
are considered and a collection of nine locally Lorentz covariant bitensors is
constructed. Four of these bitensors have been previously described in [Phys.
Rev. A 105, 032402 (2022), arXiv:2103.07784]. The collection of bitensors has
the property that all nine bitensors are simultaneously zero if and only if the
state of the two particles is a product state. Thus this collection of
bitensors indicates any type of spinor entanglement between two spacelike
separated Dirac particles.",2308.03482v1
2023-08-08,The Landau equation with moderate soft potentials: An approach using $\varepsilon$-Poincaré inequality and Lorentz spaces,"This document presents an elementary approach using $\varepsilon$-Poincar\'e
inequality to prove generation of $L^{p}$-bounds, $p\in(1,\infty)$, for the
homogeneous Landau equation with moderate soft potentials $\gamma\in[-2,0)$.
The critical case $\gamma=-2$ uses an interpolation approach in the realm of
Lorentz spaces and entropy. Alternatively, a direct approach using the
Hardy-Littlewood-Sobolev (HLS) inequality and entropy is also presented. On
this basis, the generation of pointwise bounds $p=\infty$ is deduced from a De
Giorgi argument.",2308.04384v1
2023-08-22,Ruled surfaces as translating solitons of the inverse mean curvature flow in the three-dimensional Lorentz-Minkowski space,"In this paper, we classify the nondegenerate ruled surfaces in the
three-dimensional Lorentz-Minkowski space that are translating solitons for the
inverse mean curvature flow. In particular, we prove the existence of
non-cylindrical ruled translating solitons, which contrast with the Euclidean
setting.",2308.11457v1
2023-08-22,Classification of ruled surfaces as homothetic self-similar solutions of the inverse mean curvature flow in the Lorentz-Minkowski 3-space,"In this paper, we classify the nondegenerate ruled surfaces in the
three-dimensional Lorentz-Minkowski space that are homothetic self-similar
solutions for the inverse mean curvature flow. This classification shows the
existence of two classes of non-cylindrical homothetic solitons: one with
lightlike rulings and another one with non-lightlike rulings.",2308.11679v1
2023-08-23,On Phase Boundaries in Relativistic Korteweg Fluids,"This is the first of several planned papers that study the existence and
local-in-time persistence of phase fronts in the Lorentz invariant Euler
equations for gases of van der Waals type, aiming at transferring earlier
results of Slemrod and of Benzoni-Gavage and collaborators to the context of
the theory of relativity. While the later papers will examine more general
admissibility criteria, this one uses and extends the author's Lorentz
invariant formulation of Korteweg's theory of capillarity, establishing a
family of phase fronts that have a regular heteroclinic profile with respect to
the associated Euler-Korteweg equations.",2308.12135v1
2023-09-22,One continuous parameter family of Dirac Lorentz scalar potentials associated with exceptional orthogonal polynomials,"We extend our recent works [ Int. J. Mod. Phys. A 38 (2023) 2350069-1] and
obtain one parameter $(\lambda)$ family of rationally extended Dirac Lorentz
scalar potentials with their explicit solutions in terms of $X_{m}$ exceptional
orthogonal polynomials. We further show that as the parameter $\lambda
\rightarrow 0$ or $-1$, we get the corresponding rationally extended Pursey and
the rationally extended Abraham-Moses type of scalar potentials respectively,
which have one bound state less than the starting scalar potentials.",2309.12965v1
2023-09-21,Global and Local Nilpotent Bases of Matrices,"In studying the unusual properties of a special Witt basis of a Clifford
geometric algebra with a Lorentz metric, a new concept of local duality makes
it possible to define any real geometric algebra by complexifying this
structure. Whereas a global basis of Witt null vectors is defined in terms of a
pair of correlated Grassmann algebras in a geometric algebra of neutral
signature, the special Witt basis of a Lorentz geometric algebra is defined in
terms of a single Grassmann algebra. The relationship between these different
concepts of duality, and their matrix representations, is studied in terms of
simple examples. A surprising connection is exhibited between discrete Fourier
and Wavelet transforms and the concept of local duality.",2309.13084v1
2023-10-23,Non-Lorentzian expansions of the Lorentz force and kinematical algebras,"We consider non-Lorentzian expansions, Galilean and Carrollian, of the
Lorentz force equation in which both the particle position and the
electro-magnetic field are expanded. There are two well-known limits in the
case of a constant field, called electric and magnetic, that are studied
separately. We show that the resulting equations of motion follow equivalently
from considering a non-linear realisation of a certain infinite-dimensional
algebras.",2310.15245v1
2023-10-30,Students' confusions about the electric field of a uniformly moving charge,"In light of a recent direct experimental confirmation of a Lorentz
contraction of Coulomb field (an electric field of a point charge in a uniform
motion), we revisit some common confusions related to it, to be mindful of in
teaching the subject. These include the questions about a radial nature of the
field, a role of the retardation effect due to a finite speed of information
transfer and some issues related to a depiction of Coulomb field by means of
the Lorentz contracted field lines.",2310.19312v1
2023-11-06,A stable Lorentz-breaking model for an antisymmetric two-tensor,"In this work we investigate possible actions for antisymmetric two-tensor
field models subject to constraints that force the field to acquire a nonzero
vacuum expectation value, thereby spontaneously breaking Lorentz invariance. In
order to assure stability, we require that the associate Hamiltonian be bounded
from below. It is shown that this requirement rules out any quadratic action
constructed only from the the antisymmetric tensor field. We then explicitly
construct a hybrid model consisting of the antisymmetric two-tensor field
together with a vector field, subject to three constraints, that is stable in
Minkowski space.",2311.03159v1
2023-11-06,Nonmetricity and hypermomentum: on the possible violation of Lorentz invariance,"We outline how the symmetry groups of spacetime are interpreted in a
gauge-theoretic approach. Specifically, we focus on the hypermomentum concept
and discuss the hyperfluid, that appropriately generalizes the perfect (Euler)
fluid of general relativity to the case of continuous media with
microstructure. We demonstrate that a possible violation of Lorentz invariance
is most adequately understood by means of non-vanishing nonmetricity of a
metric-affine geometry of spacetime.",2311.03160v1
2023-12-01,Rectified Lorentz Force from Thermal Current Fluctuations,"In a conducting medium held at finite temperature, free carriers are
performing Brownian motion and generate fluctuating electromagnetic fields. We
compute the averaged Lorentz force density that turns out nonzero in a thin
sub-surface layer, pointing towards the surface, while vanishing in the bulk.
This is an elementary example of rectified fluctuations, similar to the Casimir
force or radiative heat transport. Our results also provide an experimental way
to distinguish between the Drude and so-called plasma models.",2312.00666v3
2023-12-01,On the Lorentz Boosted Parallel Plate Casimir Cavity,"Two perfectly conducting, infinite parallel plates will restrict the
electromagnetic vacuum, producing an attractive force. This phenomenon is known
as the Casimir effect. Here we use electromagnetic field correlators to define
the local interaction between the plates and the vacuum, which gives rise to a
renormalized stress-energy tensor. We then show that a Lorentz boost of the
underlying electric and magnetic fields that comprise the correlators will
produce the correct stress-energy tensor in the boosted frame. The infinite
surface divergences of the field correlators will transform appropriately, such
that they cancel out in the boosted frame and produce the desired finite
result.",2312.00898v1
2023-12-21,"Absorption, scattering, quasinormal modes and shadow by canonical acoustic black holes in Lorentz-violating background","In the present work, we study the scattering for a black hole described by
the canonical acoustic metric with Lorentz violation using asymptotic and
numerical methods. In this scenario, we also check the effects of quasinormal
modes and the acoustic shadow radius. In the eikonal limit the relationship
between the shadow radius and the real part of the quasinormal frequency is
preserved.",2312.14258v1
2023-12-23,On orbital stability of solitons for 2D Maxwell-Lorentz equations,"We prove the orbital stability of soliton solutions for 2D Maxwell--Lorentz
system with extended charged particle. The solitons corresponds to the uniform
motion and rotation of the particle.
  We reduce the corresponding Hamilton system by the canonical transformation
via transition to a comoving frame. The solitons are the critical points of the
reduced Hamiltonian. The key point of the proof is a lower bound for the
Hamiltonian.",2312.15294v1
2024-03-08,Impurity in a zero-temperature three-dimensional Fermi gas,"We consider an impurity in a sea of zero-temperature fermions uniformly
distributed throughout the space. The impurity scatters on fermions. On
average, the momentum of impurity decreases with time as $t^{-1/(d+1)}$ in $d$
dimensions, and the momentum distribution acquires a scaling form in the long
time limit. We solve the Lorentz-Boltzmann equation for the scaled momentum
distribution of the impurity in three dimensions. The solution is a combination
of confluent hypergeometric functions. In two spatial dimensions, the
Lorentz-Boltzmann equation is analytically intractable, so we merely extract a
few exact predictions about asymptotic behaviors when the scaled momentum of
the impurity is small or large.",2403.05057v1
2024-04-05,Gravitational lensing by a Lorentz-violating black hole,"In this work, we study the gravitational lensing by a Lorentz-violating (LV)
black hole inspired by the recent contribution [1]. Explicitly, we concentrate
on a specific application: we perform the computation of gravitational lensing
effects under the strong field limit. In particular, we analytically derive the
deflection angle so that the lens equation can also be addressed. This
methodological approach yields physically measurable outcomes, including the
determination of relativistic image positions and their corresponding
magnifications. As an application of this methodology, we consider the
gravitational lensing by Sagittarius A${}^*$ and obtain the corresponding
observables expressed as functions of the LV parameter.",2404.04176v1
1995-01-26,Electron Energy Losses Near Pulsar polar Caps,"We present results of a model for the energetics of electrons accelerated by
the large electric fields generated by a rotating highly magnetized neutron
star. The energy loss mechanisms we consider in our calculations include
magnetic Compton scattering of thermal x-ray photons, triplet pair production,
and curvature radiation emission. The electron acceleration mechanism is
assumed to operate only to a height above the polar cap approximately equal to
the polar cap radius. We find several interesting results. First, magnetic
Compton scattering is the dominant energy loss process when the electron
Lorentz factors are < few x10^6 for typical gamma-ray pulsar magnetic fields
and surface temperatures measured by ROSAT. The amount of energy converted to
photons by accelerated electrons ranges from ~10% to ~100% of gamma_0 mc^2
where gamma_0 is the maximum Lorentz factor an electron can attain with no
radiative losses. We also find that if B > 10^13 G and T > 3x10^6 K, the
Lorentz factors of the electrons can be limited to values < 10^3 assuming
values for the size of the neutron star thermal polar cap comparable to the
polar cap size determined by the open field lines. Such small Lorentz factors
may be capable of explaining the gamma-ray emission from PSR 1509-58 which is
observed only at energies <1 MeV. We calculated the fraction of the electron's
kinetic energy that is converted to gamma rays for the three gamma-ray pulsars
which show thermal x-ray spectra, namely Vela (60%), Geminga (5%), and PSR
1055-52 (20%).",9501094v1
1999-01-05,A Comparison of the Morphology and Stability of Relativistic and Nonrelativistic Jets,"We compare results from a relativistic and a nonrelativistic set of 2D
axisymmetric jet simulations. For a set of five relativistic simulations that
either increase the Lorentz factor or decrease the adiabatic index we compute
nonrelativistic simulations with equal useful power or thrust. We examine these
simulations for morphological and dynamical differences, focusing on the
velocity field, the width of the cocoon, the age of the jets, and the internal
structure of the jet itself. The primary result of these comparisons is that
the velocity field of nonrelativistic jet simulations cannot be scaled up to
give the spatial distribution of Lorentz factors seen in relativistic
simulations. Since the local Lorentz factor plays a major role in determining
the total intensity for parsec scale extragalactic jets, this suggests that a
nonrelativistic simulation cannot yield the proper intensity distribution for a
relativistic jet. Another general result is that each relativistic jet and its
nonrelativistic equivalents have similar ages (in dynamical time units, =
R/a_a, where R is the initial radius of a cylindrical jet and a_a is the sound
speed in the ambient medium). In addition to these comparisons, we have
completed four new relativistic simulations to investigate the effect of
varying thermal pressure on relativistic jets. The simulations generally
confirm that faster (larger Lorentz factor) and colder jets are more stable,
with smaller amplitude and longer wavelength internal variations. The apparent
stability of these jets does not follow from linear normal mode analysis, which
suggests that there are available growing Kelvin-Helmholtz modes. (Abridged.)",9901046v1
1999-01-18,Radiation force on relativistic jets in active galactic nuclei,"Radiative deceleration of relativistic jets in active galactic nuclei as the
result of inverse Compton scattering of soft photons from accretion discs is
discussed. The Klein-Nishina (KN) cross section is used in the calculation of
the radiation force due to inverse Compton scattering. Our result shows that
deceleration due to scattering in the KN regime is important only for jets
starting with a bulk Lorentz factor larger than 1000. When the bulk Lorentz
factor satisfies this condition, particles scattering in the Thomson regime
contribute positively to the radiation force (acceleration), but those
particles scattering in the KN regime are dominant and the overall effect is
deceleration. In the KN limit, the drag due to Compton scattering, though less
severe than in the Thomson limit, strongly constrains the bulk Lorentz factor.
Most of the power from the deceleration goes into radiation and hence the
ability of the jet to transport significant power (in particle kinetic energy)
out of the subparsec region is severely limited. The deceleration efficiency
decreases significantly if the jet contains protons and the proton to electron
number density ratio satisfies the condition $n_p/n_{e0}>2\gamma_{\rm
min}/\mu_p$ where $\gamma_{\rm min}$ is the minimum Lorentz factor of
relativistic electrons (or positrons) in the jet frame and $\mu_p$ is the
proton to electron mass ratio.",9901223v1
2000-08-07,Planck-scale deformation of Lorentz symmetry as a solution to the UHECR and the TeV-$γ$ paradoxes,"One of the most puzzling current experimental physics paradoxes is the
arrival on Earth of Ultra High Energy Cosmic Rays with energies above the GZK
threshold. The recent observation of 20TeV photons from Mk 501 is another
somewhat similar paradox. Several models have been proposed for the UHECR
paradox. No solution has yet been proposed for the TeV-$\gamma$ paradox.
Remarkably, the drastic assumption of a violation of ordinary Lorentz
invariance would resolve both paradoxes. We present a formalism for the
description of the type of Lorentz-invariance deformation (LID) that could be
induced by non-trivial short-distance structure of space-time, and we show that
this formalism is well suited for comparison of experimental data with LID
predictions. We use the UHECR and TeV-$\gamma$ data, as well as bounds on
time-of-flight differences between photons of different energies, to constrain
the LID parameter space. A model with only two parameters, an energy scale and
a dimensionless parameter characterizing the functional dependence on the
energy scale, is shown to be sufficient to solve both the UHECR and the
TeV-$\gamma$ threshold anomalies while satisfying the time-of-flight bounds.
The allowed region of the two-parameter space is relatively small, but,
remarkably, it fits perfectly the expectations of the quantum-gravity-motivated
space-time models known to support such deformations of Lorentz invariance:
integer value of the dimensionless parameter and characteristic energy scale
constrained to a narrow interval in the neighborhood of the Planck scale.",0008107v1
2001-12-18,A fireworks model for Gamma-Ray Bursts,"The energetics of the long duration GRB phenomenon is compared with models of
a rotating Black Hole (BH) in a strong magnetic field generated by an accreting
torus. A rough estimate of the energy extracted from a rotating BH with the
Blandford-Znajek mechanism is obtained with a very simple assumption: an
inelastic collision between the rotating BH and the torus. The GRB energy
emission is attributed to an high magnetic field that breaks down the vacuum
around the BH and gives origin to a e+- fireball. Its subsequent evolution is
hypothesized, in analogy with the in-flight decay of an elementary particle, to
evolve in two distinct phases. The first one occurs close to the engine and is
responsible of energizing and collimating the shells. The second one consists
of a radiation dominated expansion, which correspondingly accelerates the
relativistic photon--particle fluid and ends at the transparency time. This
mechanism simply predicts that the observed Lorentz factor is determined by the
product of the Lorentz factor of the shell close to the engine and the Lorentz
factor derived by the expansion. An anisotropy in the fireball propagation is
thus naturally produced, whose degree depends on the bulk Lorentz factor at the
end of the collimation phase.",0112432v3
2003-01-13,Uses and limitations of relativistic jet proper motions: lessons from galactic microquasars,"It is shown that the two-sided jet proper motions observed from the galactic
microquasars GRS 1915+105 and GRO J1655-40 in practice only allow us to place
lower limits on the Lorentz factors of the outflows. As a consequence, it is
not possible to rule out the possibility that jets from X-ray binaries are just
as relativistic as those from active galactic nuclei (AGN). This results from
the fact that distance estimates place the sources, within uncertainties, at
the maximum distance d(max) which corresponds to an intrinsic velocity v=c. The
general case is explored, for a range of intrinsic Lorentz factors and angles
to the line of sight, and it is shown that a source of significantly
relativistic jets will nearly always be observed close to d(max) and as a
result it is unlikely that we will ever be able to measure with any accuracy
the Lorentz factor of a jet from two-sided proper motions. We will generally
not be able to do more than place a lower limit on the Lorentz factor of the
flow, and this limit is naturally even lower in the cases where we only observe
the approaching jet. On the other hand, under the assumption that any two-sided
jets we see are intrinsically relativistic, we can confidently place the source
at a distance d ~ d(max). As a result, observations of two-sided proper motions
in relativistic jets from AGN would be extremely important for calibration of
the cosmological distance scale. (ABRIDGED).",0301225v2
2005-08-29,Early Afterglows in Wind Environments Revisited,"When a cold shell sweeps up the ambient medium, a forward shock and a reverse
shock will form. We analyze the reverse-forward shocks in a wind environment,
including their dynamics and emission. An early afterglow is emitted from the
shocked shell, e.g., an optical flash may emerge. The reverse shock behaves
differently in two approximations: relativistic and Newtonian cases, which
depend on the parameters, e.g., the initial Lorentz factor of the ejecta. If
the initial Lorentz factor is much less than $114 E_{53}^{1/4}
\Delta_{0,12}^{-1/4} A_{*,-1}^{-1/4}$, the early reverse shock is Newtonian.
This may take place for the wider of a two-component jet, an orphan afterglow
caused by a low initial Lorentz factor, and so on. The synchrotron self
absorption effect is significant especially for the Newtonian reverse shock
case, since the absorption frequency $\nu_a$ is larger than the cooling
frequency $\nu_c$ and the minimum synchrotron frequency $\nu_m$ for typical
parameters. For the optical to X-ray band, the flux is nearly unchanged with
time during the early period, which may be a diagnostic for the low initial
Lorentz factor of the ejecta in a wind environment. We also investigate the
early light curves with different wind densities, and compare them with these
in the ISM model.",0508602v1
2006-01-23,The possible source of the UHECR observed in AGASA Experiment,"In this paper the results of AGASA experiment is discussed. It is argued that
the UHECR radiation is composed of long lived particles with mass, where is the
proton mass. Keywords: UHECR; Modified Lorentz transformation; New particles.
PACS: 96.50.S, 96.50sb, 13.85Tp",0601511v1
2007-03-28,A new method of determining the initial size and Lorentz factor of gamma-ray burst fireballs using a thermal emission component,"In recent years increasing evidence has emerged for a thermal component in
the gamma- and X-ray spectrum of the prompt emission phase in gamma-ray bursts.
The temperature and flux of the thermal component show a characteristic break
in the temporal behavior after a few seconds. We show here, that measurements
of the temperature and flux of the thermal component at early times (before the
break) allow the determination of the values of two of the least restricted
fireball model parameters: the size at the base of the flow and the outflow
bulk Lorentz factor. Relying on the thermal emission component only, this
measurement is insensitive to the inherent uncertainties of previous estimates
of the bulk motion Lorentz factor. We give specific examples of the use of this
method: for GRB970828 at redshift z=0.9578, we show that the physical size at
the base of the flow is r_0 = (2.9+-1.8)*10^8 Y_0^{-3/2} cm and the Lorentz
factor of the flow is Gamma = (305\+-28) Y_0^{1/4}, and for GRB990510 at
z=1.619, r_0=(1.7+-1.7)*10^8 Y_0^{-3/2} cm and Gamma=(384+-71) Y_0^{1/4}, where
Y = 1 Y_0 is the ratio between the total fireball energy and the energy emitted
in gamma- rays.",0703734v2
2002-02-03,Erratum: Effective Lorentz Force due to Small-Angle Impurity Scattering: Magnetotransport in High-$T_c$ Superconductors,"The equations in cond-mat/0011020 and Phys. Rev, Lett. 86, 4652 (2001) are
valid but a numerical estimate in the paper is incorrect.",0202040v1
1993-12-29,On the alternative description of complex holomorphic and Lorentz geometries in four dimensions. II. Appendix,"This supplementary part of the paper gr-qc 9312038 contains the necessary
proofs of the claims stated in the main part.",9312039v1
2002-05-21,Nonlinear realizations of Lorentz symmetry,"This paper withdrawn -- it has been revised and merged with gr-qc/0205067
(Conservation laws in ""Doubly Special Relativities""; Simon Judes and Matt
Visser)",0205093v2
2003-05-03,A Simple Deformation of Special Relativity,"A deformation of special relativity based on a dispersion relation with an
energy independent speed of light and a symmetry between positive and negative
energy states is proposed. The deformed Lorentz transformations, generators and
algebra are derived and some consequences are discussed.",0305015v1
2003-09-04,On a modified-Lorentz-transformation based gravity model confirming basic GRT experiments,"Implementing Poincar\'e's `geometric conventionalism' a scalar
Lorentz-covariant gravity model is obtained based on gravitationally modified
Lorentz transformations (or GMLT). The modification essentially consists of an
appropriate space-time and momentum-energy scaling (""normalization"") relative
to a nondynamical flat background geometry according to an isotropic,
nonsingular gravitational `affecting' function Phi(r). Elimination of the
gravitationally `unaffected' S_0 perspective by local composition of space-time
GMLT recovers the local Minkowskian metric and thus preserves the invariance of
the locally observed velocity of light. The associated energy-momentum GMLT
provides a covariant Hamiltonian description for test particles and photons
which, in a static gravitational field configuration, endorses the four `basic'
experiments for testing General Relativity Theory: gravitational i) deflection
of light, ii) precession of perihelia, iii) delay of radar echo, iv) shift of
spectral lines. The model recovers the Lagrangian of the Lorentz-Poincar\'e
gravity model by Torgny Sj\""odin and integrates elements of the precursor
gravitational theories, with spatially Variable Speed of Light (VSL) by
Einstein and Abraham, and gravitationally variable mass by Nordstr\""om.",0309023v2
2003-12-30,Phenomenology of Doubly Special Relativity,"Investigations of the possibility that some novel ``quantum"" properties of
spacetime might induce a modification dispersion relation focused at first on
scenarios with Planck-scale violations of Lorentz symmetry. More recently
several studies have considered the possibility of a ``doubly special
relativity"", in which the modification of the dispersion relation emerges from
a framework with both the Planck scale and the speed-of-light scale as
characteristic scales of a deformation of the Lorentz transformations. For the
schemes with broken Lorentz symmetry at the Planck scale there is a large
literature on the derivation of experimental limits. We provide here a
corresponding analysis for the doubly-special-relativity framework. We find
that the analyses of photon stability, synchrotron radiation, and threshold
conditions for particle production in collision processes, the three contexts
which are considered as most promising for constraining the
broken-Lorentz-symmetry scenario, cannot provide significant constraints on
doubly-special-relativity parameter space. However, certain types of analyses
of gamma-ray bursts are sensitive to the symmetry deformation. A key element of
our study is an observation that removes a possible sign ambiguity for the
doubly-special-relativity framework. This result also allows us to characterize
more sharply the differences between the doubly-special-relativity framework
and the framework of k-Poincare Hopf algebras, two frameworks which are often
confused with each other in the literature.",0312124v1
2004-10-18,Freely falling observers,"We show that the field equations of the Schwarzschild geometry are invariant
under passive Lorentz transformations to a freely falling system. We decompose
the field equations with respect to the accelerated system and find that the
force of gravity is not transformed away but dynamically compensated.",0410085v1
2005-09-10,Space-times produced by a time-dependent scalar field,"Models of Lorentz/diffeomorphism violation frequently make use of a
time-dependent scalar field. We investigate space-times produced by such a
field.",0509037v1
2006-10-17,The Lorentz force equation as Fermi-Walker transport in geometrodynamics,"A new tetrad introduced within the framework of geometrodynamics for non-null
electromagnetic fields allows for the geometrical analysis of the Lorentz force
equation and its solutions in curved spacetimes. When expressed in terms of
this new tetrad, the electromagnetic field displays explicitly maximum
simplification, and the degrees of freedom are manifestly revealed. In our
manuscript we are deducing the Lorentz force equation on purely Riemannian
geometrical grounds. The equation arises on the basis of Frenet-Serret analysis
through the use of our new tetrads and gauge invariance arguments only. The
force is deduced through a geometrical construction that precludes any other
mathematical form other than the one already accepted. Therefore, a significant
and fundamental result such as the first geometrical proof on the necessity of
the force in the equation to have the structure already accepted in physics and
not any other, is given. Through the use of the Frenet-Serret formulae and
gauge invariance arguments we are also able to express in terms of the new
tetrad vectors the Lorentz force equation as a generalized form of Fermi-Walker
transport.",0610085v3
2002-09-17,Measurements of Compton Scattered Transition Radiation at High Lorentz Factors,"X-ray transition radiation can be used to measure the Lorentz factor of
relativistic particles. Standard transition radiation detectors (TRDs)
typically incorporate thin plastic foil radiators and gas-filled x-ray
detectors, and are sensitive up to \gamma ~ 10^4. To reach higher Lorentz
factors (up to \gamma ~ 10^5), thicker, denser radiators can be used, which
consequently produce x-rays of harder energies (>100 keV). At these energies,
scintillator detectors are more efficient in detecting the hard x-rays, and
Compton scattering of the x-rays out of the path of the particle becomes an
important effect. The Compton scattering can be utilized to separate the
transition radiation from the ionization background spatially. The use of
conducting metal foils is predicted to yield enhanced signals compared to
standard nonconducting plastic foils of the same dimensions. We have designed
and built a Compton Scatter TRD optimized for high Lorentz factors and exposed
it to high energy electrons at the CERN SPS. We present the results of the
accelerator tests and comparisons to simulations, demonstrating 1) the
effectiveness of the Compton Scatter TRD approach; 2) the performance of
conducting aluminum foils; and 3) the ability of a TRD to measure energies
approximately an order of magnitude higher than previously used in very high
energy cosmic ray studies.",0209038v3
2005-01-13,Lagrangian Density for the Vacuum,"In this paper, the Lagrangian density for the vacuum is mainly discussed,
meanwhile, the matter field, the modified Lorentz transformation relations and
the reasons for the invariance of the velocity of light in the vacuum are also
discussed.",0501032v1
2005-06-27,Tests of Lorentz violation in muon antineutrino to electron antineutrino oscillations,"A recently developed Standard-Model Extension (SME) formalism for neutrino
oscillations that includes Lorentz and CPT violation is used to analyze the
sidereal time variation of the neutrino event excess measured by the Liquid
Scintillator Neutrino Detector (LSND) experiment. The LSND experiment,
performed at Los Alamos National Laboratory, observed an excess, consistent
with neutrino oscillations, of ${\bar\nu}_e$ in a beam of ${\bar\nu}_\mu$. It
is determined that the LSND oscillation signal is consistent with no sidereal
variation. However, there are several combinations of SME coefficients that
describe the LSND data; both with and without sidereal variations. The scale of
Lorentz and CPT violation extracted from the LSND data is of order $10^{-19}$
GeV for the SME coefficients $a_L$ and $E \times c_L$. This solution for
Lorentz and CPT violating neutrino oscillations may be tested by other short
baseline neutrino oscillation experiments, such as the MiniBooNE experiment.",0506067v2
2006-07-29,Search for CPT and Lorentz Violation in B0-B0bar Oscillations with Inclusive Dilepton Events,"We report preliminary results of a search for CPT and Lorentz violation in
B0-B0bar oscillations using an inclusive dilepton sample collected by the BABAR
experiment at the PEP-II B Factory. Using a sample of 232 million BBbar pairs,
we search for time-dependent variations in the complex CPT parameter z = z0 +
z1*cos(Omega*t^ + phi) where Omega is the Earth's sidereal frequency and t^ is
sidereal time. We measure Im(z0) = (-14.1 +- 7.3(stat) +- 2.4(syst)) x 10E-3,
DeltaGamma*Re(z0) = (-7.2 +- 4.1(stat) +- 2.1(syst)) x 10E-3 ps-1, Im(z1) =
(-24.0 +- 10.7(stat) +- 5.9(syst)) x 10E-3, and DeltaGamma*Re(z1) = (-18.8 +-
5.5(stat) +- 4.0(syst)) x 10E-3 ps-1, where DeltaGamma is the difference
between the decay rates of the neutral B mass eigenstates. The statistical
correlation between the measurements of Im(z0) and DeltaGamma*Re(z0) is 76%;
between Im(z1) and DeltaGamma*Re(z1) it is 79%. These results are used to
evaluate expressions involving coefficients for Lorentz and CPT violation in
the general Lorentz-violating standard-model extension. In a complementary
approach, we examine the spectral power of periodic variations in z over a wide
range of frequencies and find no significant signal.",0607103v1
1993-12-09,Heavy quark supermultiplet excitations,"Lorentz covariant wave functions for meson and baryon supermultiplets are
simply derived by boosting $SU(2)_J$ representations corresponding to
multiquark systems at rest.",9312250v1
1999-07-06,A possible alternative to the Breit frame in DIS,A new Lorentz frame for DIS jet finding is suggested.,9907250v1
2002-09-23,Threshold effects and Planck scale Lorentz violation: combined constraints from high energy astrophysics,"Recent work has shown that dispersion relations with Planck scale Lorentz
violation can produce observable effects at energies many orders of magnitude
below the Planck energy M. This opens a window on physics that may reveal
quantum gravity phenomena. It has already constrained the possibility of Planck
scale Lorentz violation, which is suggested by some approaches to quantum
gravity. In this work we carry out a systematic analysis of reaction
thresholds, allowing unequal deformation parameters for different particle
dispersion relations. The thresholds are found to have some unusual properties
compared with standard ones, such as asymmetric momenta for pair creation and
upper thresholds. The results are used together with high energy observational
data to determine combined constraints. We focus on the case of photons and
electrons, using vacuum Cerenkov, photon decay, and photon annihilation
processes to determine order unity constraints on the parameters controlling
O(E/M) Lorentz violation. Interesting constraints for protons (with photons or
pions) are obtained even at O((E/M)^2), using the absence of vacuum Cerenkov
and the observed GZK cutoff for ultra high energy cosmic rays. A strong
Cerenkov limit using atmospheric PeV neutrinos is possible for O(E/M)
deformations provided the rate is high enough. If detected, ultra high energy
cosmological neutrinos might yield limits at or even beyond O((E/M)^2).",0209264v2
2002-11-06,Fluctuation Induced Critical Behavior at Non-Zero Temperature and Chemical Potential,"We discuss phase transitions in relativistic systems as a function of both
chemical potential and temperature. The presence of a chemical potential
explicitly breaks Lorentz invariance and may additionally break other internal
symmetries. This introduces new subtleties in the determination of the critical
properties. We discuss separately three characteristic effects of a nonzero
chemical potential. Firstly, we consider only the explicit breaking of Lorentz
invariance using a scalar field theory with a global U(1) symmetry. Secondly,
we study the explicit breaking of an internal symmetry in addition to Lorentz
invariance using two--color QCD at nonzero baryonic chemical potential.
Finally, we consider the spontaneous breaking of a symmetry using three-color
QCD at nonzero baryonic and isospin chemical potential. For each case, we
derive the appropriate three-dimensional effective theory at criticality and
study the effect of the chemical potential on the fixed point structure of the
$\beta$-functions. We find that the order of the phase transition is not
affected by the explicit breaking of Lorentz invariance but is sensitive to the
breaking of additional symmetries by the chemical potential.",0211086v2
2002-11-07,Lorentz Symmetry and Ultra-High-Energy Cosmic Rays,"We discuss the possibility of explaining the observation of ultra-high-energy
cosmic rays with energy above the GZK cutoff, saving the relativity principle
and the (possibly deformed) Lorentz symmetry, as proposed recently by several
authors. Since it is known that the Lie group structure of the Lorentz group
cannot be deformed, we study the deformations (up to isomorphisms) of the
mass-shell, considered as an abstract three-dimensional homogeneous space. We
find that in the massive case the mass-shell cannot be deformed and in the
massless case there are deformations, but their physical interpretation is
problematic. The components of the four-momentum are considered as (redundant)
coordinates on the abstract mass-shell. Reinterpreting an old result, we note
that if the four-momentum is conserved its components must be the usual ones,
with linear Lorentz transformation properties. Even if four-momentum is not
conserved at high center-of-mass energies, the linearly transforming
coordinates can always be used to describe in a convenient way the kinematics
of collision processes and they satisfy the GKZ cutoff. We suggest that, if one
wants to save the relativity principle, one should look for new physics in the
collisions between the ultra-high-energy cosmic rays and the nuclei of the high
atmosphere.",0211094v2
2004-02-19,Feynman's Branes and Feynman's Oscillators,"Based on Feynman's lifetime efforts on quantum mechanics and relativity, it
is concluded that the basic difference between field theory and string theory
is that field theory is based on running waves while string theory should deal
with standing waves in the Lorentz-covariant regime.
  At the 1970 spring meeting of the American Physical Society held in
Washington, DC, R. P. Feynman stunned the audience by proposing harmonic
oscillators for relativistic bound states, instead of Feynman diagrams. His
talk was later published in the paper of Feynman, Kislinger, and Ravndal [Phys.
Rev. D, Vol. 3, 2706 (1971)]. These authors noted that the hadron mass spectra
can be predicted by the degeneracy of the three-dimensional harmonic
oscillators. In so doing, they started with the Lorentz-invariant differential
equation for the harmonic oscillator, and obtained Lorentz invariant solutions.
However, their solutions are not normalizable in the time-separation variable
and cannot carry probability interpretation. It is pointed out that there are
solutions normalizable in the time-separation variable within the framework of
Wigner's little-group representation of the Poincar\'e group. These solutions
are not invariant but covariant under Lorentz transformations. These solutions
give a covariant bound-state model which gives the quark model and the parton
model as two different limiting cases, in the low- and high-speed limits
respectively.",0402202v1
2004-07-02,Universal Dynamics of Spontaneous Lorentz Violation and a New Spin-Dependent Inverse-Square Law Force,"We study the universal low-energy dynamics associated with the spontaneous
breaking of Lorentz invariance down to spatial rotations. The effective
Lagrangian for the associated Goldstone field can be uniquely determined by the
non-linear realization of a broken time diffeomorphism symmetry, up to some
overall mass scales. It has previously been shown that this symmetry breaking
pattern gives rise to a Higgs phase of gravity, in which gravity is modified in
the infrared. In this paper, we study the effects of direct couplings between
the Goldstone boson and standard model fermions, which necessarily accompany
Lorentz-violating terms in the theory. The leading interaction is the coupling
to the axial vector current, which reduces to spin in the non-relativistic
limit. A spin moving relative to the ""ether"" rest frame will emit Goldstone
Cerenkov radiation. The Goldstone also induces a long-range inverse-square law
force between spin sources with a striking angular dependence, reflecting the
underlying Goldstone shockwaves and providing a smoking gun for this theory. We
discuss the regime of validity of the effective theory describing these
phenomena, and the possibility of probing Lorentz violations through Goldstone
boson signals in a way that is complementary to direct tests in some regions of
parameter space.",0407034v3
1993-10-01,Integrable Generalisations of the 2-dimensional Born Infeld Equation,"The Born-Infeld equation in two dimensions is generalised to higher
dimensions whilst retaining Lorentz Invariance and complete integrability. This
generalisation retains homogeneity in second derivatives of the field.",9310005v1
1994-08-30,The Dirac Equation Revisited,"A peculiar representation of the Lorentz group is suggested as a starting
point for a consistent approach to relativistic quantum theory.",9408166v2
2000-10-09,Democratic Supersymmetry,"We present generalisations of N-extended supersymmetry algebras in four
dimensions, using Lorentz covariance and invariance under permutation of the N
supercharges as selection criteria.",0010056v2
2000-10-11,TCP in q-Lorentz Theories,"The connection between spin and statistics implied by the continuous Lorentz
group together with strong reflection (TCP) is shown to hold also for the
q-Lorentz group.",0010089v1
2001-06-28,Interpolating gauges and the importance of a careful treatment of epsilon term,"We consider the use of interpolating gauges (with a gauge function (F[A;alpha
]) in gauge theories to connect the results in a set of different gauges in the
path-integral formulation. We point out that the results for physical
observables are very sensitive to the epsilon term that we have to add to deal
with singularities and thus cannot be left out of a discussion of
gauge-independence generally. We further point out, with reasons, that the fact
that we can ignore this term in the discussion of gauge independence while
varying of the gauge parameter in Lorentz-type covariant gauges is an exception
rather than a rule . We show that generally gauge-independence requires that
the epsilon-term has to be varied with alpha. We further show that if we make a
naive use of the epsilon term -i\int d^{4}x[{1/2}A^{2}-\bar{c}c]) (that is
appropriate for the Feynman gauge) for general interpolating gauges with
arbitrary parameter values [i.e.alpha], we cannot preserve gauge independence
[except when we happen to be in the infinitesimal neighborhood of the
Lorentz-type gauges]. We show with an explicit example that for such a naive
use of an epsilon-term, we develop serious pathology in the path-integral as
alpha is/are varied. We point out that correct way to fix the epsilon-term in a
path-integral in a non-Lorentz gauge is by connecting the path-integral to the
Lorentz-gauge path-integral with correct epsilon-term as has been done using
the finite field-dependent BRS transformations in recent years.",0106264v2
2002-10-15,Deformed Lorentz Symmetry and High-Energy Astrophysics (III),"Lorentz symmetry violation (LSV) can be generated at the Planck scale, or at
some other fundamental length scale, and naturally preserve Lorentz symmetry as
a low-energy limit (deformed Lorentz symmetry, DLS). DLS can have important
implications for ultra-high energy cosmic-ray physics (see papers
physics/0003080 - hereafter referred to as I -, astro-ph/0011181 and
astro-ph/0011182, and references quoted in these papers). A crucial question is
how DLS can be extended to a deformed Poincar\'e symmetry (DPS), and what can
be the dynamical origin of this phenomenon. In a recent paper (hep-th/0208064,
hereafter referred to as II), we started a discussion of proposals to identify
DPS with a symmetry incorporating the Planck scale (like doubly special
relativity, DSR) and suggested new ways in similar directions. Implications for
models of quadratically deformed relativistic kinematics (QDRK) and linearly
deformed relativistic kinematics (LDRK) were also discussed. We pursue here our
study of these basic problems, focusing on the possibility to relate deformed
relativistic kinematics (DRK) to new space-time dimensions and compare our QDRK
model, in the form proposed since 1997, which the Kirzhnits-Chechin (KCh) and
Sato-Tati (ST) models. It is pointed out that, although the KCh model does not
seem to work such as it was formulated, our more recent proposals can be
related to suitable extensions of this model generalizing the Finsler algebras
(even to situations where a preferred physical inertial frame exists) and using
the Magueijo-Smolin transformation as a technical tool.",0210141v1
2004-06-21,Next-to-Maximal Helicity Violating Amplitudes in Gauge Theory,"Using the novel diagrammatic rules recently proposed by Cachazo, Svrcek, and
Witten, I give a compact, manifestly Lorentz-invariant form for tree-level
gauge-theory amplitudes with three opposite helicities.",0406175v1
2004-09-23,Doubly Special Relativity in Position Space Starting from the Conformal Group,"We propose version of doubly special relativity theory starting from position
space. The version is based on deformation of ordinary Lorentz transformations
due to the special conformal transformation. There is unique deformation which
does not modify rotations. In contrast to the Fock-Lorentz realization (as well
as to recent position-space proposals), maximum signal velocity is position
(and observer) independent scale in our formulation by construction. The
formulation admits one more invariant scale identified with radius of
three-dimensional space-like hypersection of space-time. We present and discuss
the Lagrangian action for geodesic motion of a particle on the DSR space. For
the present formulation, one needs to distinguish the canonical (conjugated to
$x^\mu$) momentum $p^\mu$ from the conserved energy-momentum. Deformed Lorentz
transformations for $x^\mu$ induce complicated transformation law in space of
canonical momentum. $p^\mu$ is not a conserved quantity and obeys to deformed
dispersion relation. The conserved energy-momentum $P^\mu$ turns out to be
different from the canonical one, in particular, $P^\mu$-space is equipped with
nontrivial commutator. The nonlinear transformations for $x^\mu$ induce the
standard Lorentz transformations in space of $P^\mu$. It means, in particular,
that composite rule for $P^\mu$ is ordinary sum. There is no problem of total
momentum in the theory. $P^\mu$ obeys the standard energy-momentum relation
(while has nonstandard dependence on velocity).",0409232v3
2006-01-16,Logarithmic scaling in gauge/string correspondence,"We study anomalous dimensions of (super)conformal Wilson operators at weak
and strong coupling making use of the integrability symmetry on both sides of
the gauge/string correspondence and elucidate the origin of their
single-logarithmic behavior for long operators/strings in the limit of large
Lorentz spin. On the gauge theory side, we apply the method of the Baxter
Q-operator to identify different scaling regimes in the anomalous dimensions in
integrable sectors of (supersymmetric) Yang-Mills theory to one-loop order and
determine the values of the Lorentz spin at which the logarithmic scaling sets
in. We demonstrate that the conventional semiclassical approach based on the
analysis of the distribution of Bethe roots breaks down in this domain. We work
out an asymptotic expression for the anomalous dimensions which is valid
throughout the entire region of variation of the Lorentz spin. On the string
theory side, the logarithmic scaling occurs when two most distant points of the
folded spinning string approach the boundary of the AdS space. In terms of the
spectral curve for the classical string sigma model, the same configuration is
described by an elliptic curve with two branching points approaching values
determined by the square root of the 't Hooft coupling constant. As a result,
the anomalous dimensions cease to obey the BMN scaling and scale
logarithmically with the Lorentz spin.",0601112v2
2006-04-11,On the different forms of the Maxwell's electromagnetic equations in a uniform media,"Two known, alternative to each other, forms of the Maxwell's electromagnetic
equations in a moving uniform media are investigated and discussed. Approach
commonly used after Minkowski is based on the two tensors:
  H^{ab} = (D, H /c) and F^{ab} = (E, cB) which transform independently of each
other at Lorentz transitions; relationships between fields change their form at
Lorentz transformations and have the form of the Minkowski equations depending
on the 4-velocity u^{a} of the moving media under an inertial reference frame.
So, the electrodynamics by Minkowski implies the absolute nature of the
mechanical motion. An alternative formalism (Rosen and others) may be developed
in the new variables. This form of the the Maxwell's equations exhibits
symmetry under modified Lorentz transformations in which everywhere instead of
the vacuum speed of light c is used the speed of light in the media, kc . In
virtue of this symmetry we might consider such a formulation of the Maxwell
theory in the media as invariant under the mechanical motion of the reference
frame.In connection with these two theoretical schemes, a point of principle
must be stressed: it might seem well-taken the requirement to perform
Poincare-Einstein clock synchronization in the uniform medias with the help of
real light signals influenced by the media, which leads us to the modified
Lorentz symmetry.",0604080v1
2006-06-09,SIM(2) and Superspace,"In this brief note we give a superspace description of the supersymmetric
nonlocal Lorentz noninvariant actions recently proposed by Cohen and Freedman.
This leads us to discover similar terms for gauge fields.",0606093v1
1997-02-24,One-complemented subspaces of real sequence spaces,"Characterizations are given for 1-complemented hyperplanes of strictly
monotone real Lorentz spaces and 1-complemented finite codimensional subspaces
(which contain at least one basis element) of real Orlicz spaces equipped with
either Luxemburg or Orlicz norm.",9702214v1
2002-10-16,Interpolation properties for some scales of approximation spaces,"We obtain a result concerning the stability under the interpolation with
functional parameter method for the approximation spaces of
Lorentz-Marcinkiewicz type and also for the approximation spaces generated by
symmetric norming functions of a certain type.",0210243v1
2006-09-06,On the existence of a proper conformal maximal disk in L^3,"In this paper we construct an example of a properly immersed maximal surface
in the Lorentz-Minkowski space L^3 with the conformal type of a disk.",0609181v2
2006-03-09,Superspinors,"We propose to replace the classical Lorentz group with a compact semisimple
Lie group. The results are rendered via the formalism of superspinors - objects
identifiable as particles or antiparticles, and governed by the Fermi-Dirac
statistics.",0603023v1
2007-02-14,Reciprocal Symmetry and the Origin of Spin,"We have shown that Reciprocal Symmetric transformation shares the algebraic
properties of Dirac Electron Theory more than Lorentz transformation and that
the origin of spin is in Reciprocal Symmetry.",0702043v1
1997-06-16,Lorentz Symmetry Violation and Very High-Energy Cross Sections,"We discuss the implications of a recently proposed pattern of Lorentz
symmetry violation on very high-energy cross sections. As a consequence of the
breaking of local Lorentz invariance by the introduction of a fundamental
length, $a$ , the kinematics is modified and the properties of final states are
fundamentally different in collider-like (two incoming particles with equal,
opposite momenta with respect to the vacuum rest frame) and fixed-target (one
of the incoming particles at rest with respect to the vacuum rest frame)
situations. In the first case, the properties of the allowed final states are
similar to relativistic kinematics, as long as the relevant wave vectors are
much smaller than the critical wave vector scale $a^{-1}$ . But, if one of the
incoming particles is close to rest in the vacuum rest frame, energy
conservation reduces the final-state phase space at very high energy and can
lead to a sharp fall of cross sections starting at incoming-particle wave
vectors well below the inverse of the fundamental length. Then, the Froissart
bound may cease to be relevant, as total cross sections seem to become much
smaller than it would be allowed by local, Lorentz-invariant, field theory.
Important experimental implications of the new scenario are found for
cosmic-ray astrophysics and for very high-energy cosmic rays reaching the
earth.",9706022v1
1998-06-23,Aberration and Special Relativity,"Section 7 of Einstein's 1905 electrodynamics paper gives frequency-shift and
aberration formulae that together describe an elongated ellipsoidal wavefront.
A Lorentz contraction of this ellipsoid solves most (but not all) of the
associated relativistic problems.",9806037v1
1998-07-22,Relativistic Effect of Velocity on Electric Charge and Lorentz Force,This paper has been withdrawn due to crucial errors.,9807043v3
2000-07-09,Classical Radiation Reaction Off-Shell Corrections to the Covariant Lorentz Force,"It has been shown by Gupta and Padmanabhan that the radiation reaction force
of the Abraham-Lorentz-Dirac equation can be obtained by a coordinate
transformation from the inertial frame of an accelerating charged particle to
that of the laboratory. We show that the problem may be formulated in a flat
space of five dimensions, with five corresponding gauge fields in the framework
of the classical version of a fully gauge covariant form of the Stueckelberg-
Feynman-Schwinger covariant mechanics (the zero mode fields of the 0,1,2,3
components correspond to the Maxwell fields). Without additional constraints,
the particles and fields are not confined to their mass shells. We show that in
the mass-shell limit, the generalized Lorentz force obtained by means of the
retarded Green's functions for the five-dimensional field equations provides
the classical Abraham-Lorentz-Dirac radiation reaction terms (with renormalized
mass and charge). We also obtain general coupled equations for the orbit and
the off-shell dynamical mass during the evolution. The theory does not admit
radiation if the particle remains identically on-shell. The structure of the
equations implies that the mass-shell deviaiton is bounded when the external
field is removed.",0007022v1
2001-08-05,Remarks on Superluminal Propagation of an Electromagnetic Wave in Air,"The significance of the Lorentz gauge as a constraint on solutions of
Maxwellian waves is discussed. It is proved that recent claims of superluminal
propagation of electromagnetic waves rely on an erroneous basis.",0108006v1
2002-11-05,Modifications of the Lorentz Force Law Complying with Galilean Transformations and the Local-Ether Propagation Model,"It is generally expected from intuition that the electromagnetic force
exerted on a charged particle should remain unchanged when observed in
different reference frames in uniform translational motion. In the special
relativity, this invariance is achieved by invoking the Lorentz transformation
of space and time. In this investigation an entirely different interpretation
of the invariance of force is presented. We propose a new model of the
electromagnetic force given in terms of the augmented potentials, which are
derived from the electric scalar potential by incorporating a velocity
difference between involved particles. The propagation of the potentials is
supposed to follow the local-ether model. All of the position vectors, time
derivatives, and velocities involved in the proposed potentials and force law
are referred specifically to their respective frames. By virtue of this
feature, the electromagnetic force is independent of reference frame simply
based on Galilean transformations. The proposed model looks quite different
from the Lorentz force law, except the electrostatic force. However, under the
common low-speed condition where the mobile charged particles forming the
current drift very slowly in a neutralizing matrix, it is shown that the
proposed model reduces to the Lorentz force law, if the latter is observed in
the matrix frame as done tacitly in common practice.",0211019v1
2003-08-08,Lorentz's theory and special relativity are completely identical,"The main content of this paper has been moved into the new version of
physics/0308035.",0308033v3
2004-09-23,The Proof that Maxwell Equations with the 3D E and B are not Covariant upon the Lorentz Transformations but upon the Standard Transformations. The New Lorentz Invariant Field Equations,"In this paper the Lorentz transformations (LT) and the standard
transformations (ST) of the usual Maxwell equations (ME) with the
three-dimensional (3D) vectors of the electric and magnetic fields, E and B
respectively, are examined using both the geometric algebra and tensor
formalisms. Different 4D algebric objects are used to represent the usual
observer dependent and the new observer independent electric and magnetic
fields. It is found that the ST of the ME differ from their LT and consequently
that the ME with the 3D E and B are not covariant upon the LT but upon the ST.
The obtained results do not depend on the character of the 4D algebric objects
used to represent the electric and magnetic fields. The Lorentz invariant field
equations are presented with 1-vectors E and B, bivectors E_{Hv} and B_{Hv} and
the abstract tensors, the 4-vectors E^{a} and B^{a}. All these quantities are
defined without reference frames, i.e., as absolute quantities. When some basis
has been introduced, they are represented as coordinate-based geometric
quantities comprising both components and a basis. It is explicitly shown that
this geometric approach agrees with experiments, e.g., the Faraday disk, in all
relatively moving inertial frames of reference, which is not the case with the
usual approach with the 3D E and B and their ST.",0409118v2
2005-04-27,Special relativity in the electromagnetic wave,"Invariance of the counted number of photons and the Lorentz-Einstein
transformations enable us to derive transformation equations for the physical
quantities introduced in order to characterize energy emission and transport in
a plane and in a spherical electromagnetic wave propagating in vacuum.",0504199v1
1996-02-02,Deformation map for generalized Kappa-Poincar'e and Kappa-Weyl algebras,"A nonlinear transformation in the momentum space is constructed which
converts the deformed action of Lorentz and Weyl generators on momenta into the
standard one.",9602005v1
1997-04-14,Lorentz-covariant stochastic wave function dynamics?,"The e-print is completely withdrawn for it was based on a report which was
not public. The author seriously apologizes because he was unaware.",9704025v3
2001-12-13,Stochastic quantization of the linearized gravitational field,"Stochastic field equations for linearized gravity are presented. The theory
is compared with the usual quantum field theory and questions of Lorentz
covariance are discussed. The classical radiation approximation is also
presented.",0112076v1
2004-09-24,Standing waves in the Lorentz-covariant world,"When Einstein formulated his special relativity, he developed his dynamics
for point particles. Of course, many valiant efforts have been made to extend
his relativity to rigid bodies, but this subject is forgotten in history. This
is largely because of the emergence of quantum mechanics with wave-particle
duality. Instead of Lorentz-boosting rigid bodies, we now boost waves and have
to deal with Lorentz transformations of waves. We now have some understanding
of plane waves or running waves in the covariant picture, but we do not yet
have a clear picture of standing waves. In this report, we show that there is
one set of standing waves which can be Lorentz-transformed while being
consistent with all physical principle of quantum mechanics and relativity. It
is possible to construct a representation of the Poincar\'e group using
harmonic oscillator wave functions satisfying space-time boundary conditions.
This set of wave functions is capable of explaining the quantum bound state for
both slow and fast hadrons. In particular it can explain the quark model for
hadrons at rest, and Feynman's parton model hadrons moving with a speed close
to that of light.",0409165v1
2007-08-16,Lorentz Invariance Violation from String Theory,"In this brief, and by no means complete, review I discuss situations in
string theory, in which Lorentz Invariance Violation may occur in a way
consistent with world-sheet conformal invariance, thereby leading to
acceptable, in principle, string backgrounds. In particular, I first discuss
spontaneous Lorentz violation in (non supersymmetric) open string field theory.
Then, I move onto a discussion of gravity-induced modified dispersion relations
in non-critical (Liouville) strings, in the sense of an induced Finsler-like
geometry depending on both coordinates and momenta, for string propagation in
non-trivial space times (such as D-particle ``foamy situations''). I pay
attention to explaining the appearance of bi-metric models from such string
theories, which could serve as examples of alternative scenaria to dark matter.
Finally, I make some comparisons with similar developments in other contexts,
such as critical strings in non-commutative space times, as well as deformed
special relativities and theories with reduced Lorentz symmetry, advocated
recently, where again Finsler geometry seems to come into play. In this latter
respect, I put the emphasis on phenomenology and attempt to answer the question
as to whether there is the possibility of experimental disentanglement of the
various approaches.",0708.2250v1
2007-09-14,Lorentz Violation in a Diffeomorphism-Invariant Theory,"In a diffeomorphism invariant theory, symmetry breaking may be a mask for
coordinate choice.",0709.2348v1
2007-09-27,Transference of bilinear multiplier operators on Lorentz spaces,"We prove a DeLeeuw type theorem of transference of boundedness for modulation
invariant multiplier operators between the groups defined by the real line and
the torus.",0709.4339v2
2007-10-04,Bilinear multipliers on Lorenzt spaces,"We give one sufficient and two necessary conditions for boundedness between
Lebesgue or Lorentz spaces of several classes of bilinear multiplier operators
closely connected with the bilinear Hilbert transform.",0710.0977v1
2007-12-20,A note on restricted X-ray transforms,"We show how the techniques introduces by Christ can be employed to derive
endpoint $L^p-L^q$ bounds for the X-ray transform associated to the line
complex generated by the curve $t\to(t,t^2,...,t^{d-1}).$ Almost-sharp Lorentz
space estimates are produced as well.",0712.3477v1
2008-03-18,Can the quark model be relativistic enough to include the parton model?,"Since quarks are regarded as the most fundamental particles which constitute
hadrons that we observe in the real world, there are many theories about how
many of them are needed and what quantum numbers they carry. Another important
question is what keeps them inside the hadron, which is known to have
space-time extension. Since they are relativistic objects, how would the hadron
appear to observers in different Lorentz frames? The hadron moving with speed
close to that of light appears as a collection of Feynman's partons. In other
words, the same object looks differently to observers in two different frames,
as Einstein's energy-momentum relation takes different forms for those
observers. In order to explain this, it is necessary to construct a quantum
bound-state picture valid in all Lorentz frames. It is noted that Paul A. M.
Dirac studied this problem of constructing relativistic quantum mechanics
beginning in 1927. It is noted further that he published major papers in this
field in 1945, 1949, 1953, and in 1963. By combining these works by Dirac, it
is possible to construct a Lorentz-covariant theory which can explain hadronic
phenomena in the static and high-speed limits, as well as in between. It is
shown also that this Lorentz-covariant bound-state picture can explain what we
observe in high-energy laboratories, including the parton distribution function
and the behavior of the proton form factor.",0803.2633v1
2008-10-02,Relativistic Mechanics and a Special Role for the Coulomb Potential,"It is shown that a nonrelativistic mechanical system involving a general
nonrelativistic potential V(|r1-r2|) between point particles at positions r1
and r2 can be extended to a Lagrangian system which is invariant under Lorentz
transformation through order v^2/c^2. However, this invariance requires the
introduction of velocity-dependent and acceleration-dependent forces between
particles. The textbook treatments of ""relativistic mechanics"" can be
misleading; the discussions usually deal with only one particle experiencing
prescribed forces and so make no mention of these additional velocity- and
acceleration-dependent forces. A simple example for a situation analogous to a
parallel-plate capacitor is analyzed for all the conservation laws of Galilean
invariance or Lorentz invariance. For this system, Galilean invariance requires
that the mechanical momentum is given by pmech=mv but places no restriction on
the position-dependent potential function. On the other hand, Lorentz
invariance requires that the mechanical momentum is given by
pmech=mv/(1-v^2/c^2)^1/2, and in addition requires that the potential function
is exactly the Coulomb potential V(|r1-r2|)=k/|r1-r2|. It is also noted that
the transmission of the interparticle-force signal at the speed of light again
suggests a special role for the Coulomb potential. A nonrelativistic particle
system interacting through the Coulomb potential becomes the Darwin Lagrangian
when extended to a system relativistic through order v^2/c^2, and then allows
extension to classical electrodynamics as a fully Lorentz-invariant theory of
interacting particles.",0810.0434v1
2009-02-11,Lorentz invariant quantization of the Yang-Mills theory free of Gribov ambiguity,"A new fomulation of the Yang-Mills theory which allows to avoid the problem
of Gribov ambiguity of the gauge fixing is proposed.",0902.1847v1
2009-04-29,Lorentz Violation in Goldstone Gravity,"We consider a theory of gravity in which a symmetric two-index tensor in
Minkowski spacetime acquires a vacuum expectation value (vev) via a potential,
thereby breaking Lorentz invariance spontaneously. When the vev breaks all the
generators of the Lorentz group, six Goldstone modes emerge, two linear
combinations of which have properties that are identical to those of the
graviton in general relativity. Integrating out massive modes yields an
infinite number of Lorentz-violating radiative-correction terms in the
low-energy effective Lagrangian. We examine a representative subset of these
terms and show that they modify the dispersion relation of the two propagating
graviton modes such that their phase velocity is direction-dependent. If the
phase velocity of the Goldstone gravitons is subluminal, cosmic rays can emit
gravi-Cherenkov radiation, and the detection of high-energy cosmic rays can be
used to constrain these radiative correction terms. Test particles in the
vicinity of the Goldstone gravitons undergo longitudinal oscillations in
addition to the usual transverse oscillations as predicted by general
relativity. Finally, we discuss the possibility of having vevs that do not
break all six generators and examine in detail one such theory.",0904.4680v1
2009-04-30,Can we probe the Lorentz factor of gamma-ray bursts from GeV-TeV spectra integrated over internal shocks?,"We revisit the high-energy spectral cutoff originating from the
electron-positron pair creation in the prompt phase of gamma-ray bursts (GRBs)
with numerical and analytical calculations. We show that the conventional
exponential and/or broken power law cutoff should be drastically modified to a
shallower broken power-law in practical observations that integrate emissions
from different internal shocks. Since the steepening is tiny for observations,
this ""smearing"" effect can generally reduce the previous estimates of the
Lorentz factor of the GRB outflows. We apply our formulation to GRB 080916C,
recently detected by the Large Area Telescope detector on the Fermi satellite,
and find that the minimum Lorentz factor can be ~600 (or even smaller values),
which is below but consistent with the previous result of ~900. Observing the
steepening energy (so-called ""pair-break energy"") is crucial to diagnose the
Lorentz factor and/or the emission site in the future observations, especially
current and future Cherenkov telescopes such as MAGIC, VERITAS, and CTA.",0904.4878v2
2009-06-09,Searching for New Physics with Ultrahigh Energy Cosmic Rays,"Ultrahigh energy cosmic rays that produce giant extensive showers of charged
particles and photons when they interact in the Earth's atmosphere provide a
unique tool to search for new physics. Of particular interest is the
possibility of detecting a very small violation of Lorentz invariance such as
may be related to the structure of space-time near the Planck scale of $\sim
10^{-35}$m. We discuss here the possible signature of Lorentz invariance
violation on the spectrum of ultrahigh energy cosmic rays as compared with
present observations of giant air showers. We also discuss the possibilities of
using more sensitive detection techniques to improve searches for Lorentz
invariance violation in the future. Using the latest data from the Pierre Auger
Observatory, we derive a best fit to the LIV parameter of $3.0^{+1.5}_{-3.0}
\times 10^{-23}$, corresponding to an upper limit of $4.5 \times 10^{-23}$ at a
proton Lorentz factor of $\sim 2 \times 10^{11}$. This result has fundamental
implications for quantum gravity models.",0906.1735v2
2009-06-18,Renormalization group in Lifshitz-type theories,"We study the one-loop renormalization and evolution of the couplings in
scalar field theories of the Lifshitz type, i.e. with different scaling in
space and time. These theories are unitary and renormalizable, thanks to higher
spatial derivative terms that modify the particle propagator at high energies,
but at the expense of explicitly breaking Lorentz symmetry. We study if and
under what conditions the Lorentz symmetry can be considered as emergent at low
energies by studying the RG evolution of the ``speed of light'' coupling
$c^2_\phi$ and, for more than one field, of $\delta c^2\equiv
c^2_{\phi_1}-c^2_{\phi_2}$ in simple models. We find that in the UV both
$c^2_\phi$ and $\delta c^2$ generally flow logarithmically with the energy
scale. A logarithmic running of $c^2$ persists also at low-energies, if $\delta
c^2 \neq 0$ in the UV. As a result, Lorentz symmetry is not recovered at low
energies with the accuracy needed to withstand basic experimental constraints,
unless all the Lorentz breaking terms, including $\delta c^2$, are unnaturally
fine-tuned to extremely small values in the UV. We expect that the
considerations of this paper will apply to any generic theory of Lifshitz type,
including a recently proposed quantum theory of gravity by Horava.",0906.3477v3
2009-10-03,The Lorentz force in atmospheres of CP stars: 56 Arietis,"The presence of electric currents in the atmospheres of magnetic chemically
peculiar (mCP) stars could bring important theoretical constrains about the
nature and evolution of magnetic field in these stars. The Lorentz force, which
results from the interaction between the magnetic field and the induced
currents, modifies the atmospheric structure and induces characteristic
rotational variability of pressure-sensitive spectroscopic features, that can
be analysed using phase-resolved spectroscopic observations. In this work we
continue the presentation of results of the magnetic pressure studies in mCP
stars focusing on the high-resolution spectroscopic observations of Bp star
56Ari. We have detected a significant variability of the Halpha, Hbeta, and
Hgamma spectral lines during full rotation cycle of the star. Then these
observations are interpreted in the framework of the model atmosphere analysis,
which accounts for the Lorentz force effects. We used the LLmodels stellar
model atmosphere code for the calculation of the magnetic pressure effects in
the atmosphere of 56Ari taking into account realistic chemistry of the star and
accurate computations of the microscopic plasma properties. The Synth3 code was
employed to simulate phase-resolved variability of Balmer lines. We demonstrate
that the model with the outward-directed Lorentz force in the dipole+quadrupole
configuration is likely to reproduce the observed hydrogen lines variation.
These results present strong evidences for the presence of non-zero global
electric currents in the atmosphere of this early-type magnetic star.",0910.0532v1
2010-03-19,Lorentz-covariant quantum transport and the origin of dark energy,"A possible explanation for the enigma of dark energy, responsible for about
76 % of the mass-energy of the universe, is obtained by requiring only that the
rigorous continuity equation (the Boltzmann transport equation) for quanta
propagating through space should have the form of a Lorentz-covariant and
dispersion-free wave equation. This requirement implies (i) properties of
space-time which an observer would describe as uniform expansion in agreement
with Hubble's law, and (ii) that the quantum transport behaves like in a
multiplicative medium with multiplication factor = 2. This inherent,
essentially explosive multiplicity of vacuum, thus caused by the requirement of
Lorentz-covariance, is suggested as a potential origin of dark energy. In
addition, it is shown (iii) that this requirement of Lorentz-covariant quantum
transport leads to an apparent accelerated expansion of the universe.
  In addition to the updated manuscript for Phys. Scr., the arXiv file also
contains a discussion of about a dozen Frequently Asked Questions from readers.
Further questions not adequately dealt with in the existing FAQ are welcome.",1003.3870v7
2010-03-29,Lessons from the decoupling limit of Horava gravity,"We consider the so-called ""healthy"" extension of Horava gravity in the limit
where the Stuckelberg field decouples from the graviton. We verify the alleged
strong coupling problem in this limit, under the assumption that no large
dimensionless parameters are put in by hand. This follows from the fact that
the dispersion relation for the Stuckelberg field does not have the desired z =
3 anisotropic scaling in the UV. To get the desired scaling and avoid strong
coupling one has to introduce a low scale of Lorentz violation and retain some
coupling between the graviton and the Stuckelberg field. We also make use of
the foliation preserving symmetry to show how the Stuckelberg field couples to
some violation of energy conservation. We source the Stuckelberg field using a
point particle with a slowly varying mass and show that two such particles feel
a constant attractive force. In this particular example, we see no Vainshtein
effect, and violations of the Equivalence Principle. The latter is probably
generic to other types of source and could potentially be used to place lower
bounds on the scale of Lorentz violation.",1003.5666v2
2010-04-02,Higgs bundles for the Lorentz group,"Using the Morse-theoretic methods introduced by Hitchin, we prove that the
moduli space of $\SO_0(1,n)$-Higgs bundles when $n$ is odd has two connected
components.",1004.0318v1
2010-04-05,Modifications to Lorentz invariant dispersion in relatively boosted frames,"We investigate the implications of energy-dependence of the speed of photons,
one of the candidate effects of quantum-gravity theories that has been most
studied recently, from the perspective of observations in different reference
frames. We examine how a simultaneous burst of photons would be measured by two
observers with a relative velocity, establishing some associated conditions for
the consistency of theories. For scenarios where the Lorentz transformations
remain valid these consistency conditions allow us to characterize the
violations of Lorentz symmetry through an explicit description of the
modification of the quantum-gravity scale in boosted frames with respect to its
definition in a preferred frame. When applied to relativistic scenarios with a
deformation of Lorentz invariance that preserves the equivalence of inertial
observers, we find an insightful characterization of the necessity to adopt in
such frameworks non-classical features of spacetime geometry, e.g. events that
are at the same spacetime point for one observer cannot be considered at the
same spacetime point for other observers. Our findings also suggest that, at
least in principle (and perhaps one day even in practice), measurements of the
dispersion of photons in relatively boosted frames can be particularly valuable
for the purpose of testing these scenarios.",1004.0575v2
2010-06-08,On (in)elastic non-dissipative Lorentz gases and the (in)stability of classical pulsed and kicked rotors,"We study numerically and theoretically the $d$-dimensional Hamiltonian motion
of fast particles through a field of scatterers, modeled by bounded, localized,
(time-dependent) potentials, that we refer to as (in)elastic non-dissipative
Lorentz gases. We illustrate the wide applicability of a random walk picture
previously developed for a field of scatterers with random spatial and/or
time-dependence by applying it to four other models. First, for a periodic
array of spherical scatterers in $d\geq2$, with a smooth (quasi)periodic
time-dependence, we show Fermi acceleration: the ensemble averaged kinetic
energy $\left<\|p(t)\|^2\right>$ grows as $t^{2/5}$. Nevertheless, the mean
squared displacement $\left<\|q(t)\|^2\right>\sim t^2$ behaves ballistically.
These are the same growth exponents as for random time-dependent scatterers.
Second, we show that in the soft elastic and periodic Lorentz gas, where the
particles' energy is conserved, the motion is diffusive, as in the standard
hard Lorentz gas, but with a diffusion constant that grows as $\|p_0\|^{5}$,
rather than only as $\|p_0\|$. Third, we note the above models can also be
viewed as pulsed rotors: the latter are therefore unstable in dimension $d\geq
2$. Fourth, we consider kicked rotors, and prove them, for sufficiently strong
kicks, to be unstable in all dimensions with $\left<\|p(t)\|^2\right>\sim t$
and $\left<\|q(t)\|^2\right>\sim t^3$. Finally, we analyze the singular case
$d=1$, where $\left< \|p(t)\|^2\right>$ remains bounded in time for
time-dependent non-random potentials whereas it grows at the same rate as above
in the random case.",1006.1556v1
2010-08-13,A Revised Limit of the Lorentz Factors of GRBs with Two Emitting Regions,"Fermi observations of GeV emission from GRBs have suggested that the Lorentz
factor of some GRBs is around a thousand or even higher. At the same time the
same Fermi observations have shown an extended GeV emission indicating that
this higher energy emission might be a part of the afterglow and it does not
come from the same region as the lower energy prompt emission. If this
interpretation is correct than we should reconsider the opacity limits on the
Loretnz factor of the emitting regions which are based on a one-zone model. We
describe here a two-zone model in which the GeV photons are emitted in a larger
radius than the MeV photons and we calculate the optical depth for pair
creation of a GeV photon passing the lower energy photons shell. We find that,
as expected, the new two-zone limits on the Lorentz factor are significantly
lower. The corresponding limits for the Fermi bursts are lower by a factor of
five compared to the one-zone model and it is possible that both the MeV and
GeV regions have relatively modest Lorentz factors (~200 - 400).",1008.2253v2
2010-09-07,Classical Lagrange Functions for the SME,"A technique is presented for finding the classical Lagrange function
corresponding to a given dispersion relation. This allows us to study the
classical analogue of the Standard-Model Extension. Developments are discussed.",1009.1383v1
2011-01-31,LIPS-thermalization of a relativistic gas,"It is argued that two-particle collisions of relativistic particles ""at a
distance"", irrespective of their position in the configuration space, generate
uniform distribution of particles in Lorentz invariant phase space.",1101.5874v1
2011-02-14,A New Limit on Planck Scale Lorentz Violation from Gamma-ray Burst Polarization,"Constraints on possible Lorentz invariance violation (LIV) to first order in
$E/M_{\rm Planck}$ for photons in the framework of effective field theory (EFT)
are discussed, taking cosmological factors into account. Then, using the
reported detection of polarized soft $\gamma$-ray emission from the
$\gamma$-ray burst GRB041219a that is indicative of an absence of vacuum
birefringence, together with a very recent improved method for estimating the
redshift of the burst, we derive constraints on the dimension 5 Lorentz
violating modification to the Lagrangian of an effective local QFT for QED. Our
new constraints are more than five orders of magnitude better than recent
constraints from observations of the Crab Nebula. We obtain the upper limit on
the Lorentz violating dimension 5 EFT parameter $|\xi|$ of $2.4 \times
10^{-15}$, corresponding to a constraint on the dimension 5 standard model
extension parameter, $k^{(5)}_{(V)00} \le 4.2 \times 10^{-34}$ GeV$^{-1}$.",1102.2784v6
2011-10-04,Violations of Lorentz invariance in the neutrino sector: an improved analysis of anomalous threshold constraints,"Recently there has been a renewed activity in the physics of violations of
Lorentz invariance in the neutrino sector. Flavor dependent Lorentz violation,
which generically changes the pattern of neutrino oscillations, is extremely
tightly constrained by oscillation experiments. Flavor independent Lorentz
violation, which does not introduce new oscillation phenomena, is much more
weakly constrained with constraints coming from time of flight and anomalous
threshold analyses. We use a simplified rotationally invariant model to
investigate the effects of finite baselines and energy dependent dispersion on
anomalous reaction rates in long baseline experiments and show numerically that
anomalous reactions do not necessarily cut off the spectrum quite as sharply as
currently assumed. We also present a revised analysis of how anomalous
reactions can be used to cast constraints from the observed atmospheric high
energy neutrinos and the expected cosmogenic ones.",1110.0783v3
2011-10-28,Consequences of the gamma-gamma attenuation in GRBs: a detailed study,"Recent detections of GeV photons in a few GRBs by Fermi-LAT have led to
strong constraints on the bulk Lorentz factor in GRB outflows. To avoid a large
gamma-gamma optical depth, minimum values of the Lorentz factor have been
estimated to be as high as 800-1200 in some bursts. Here we present a detailed
calculation of the gamma-gamma optical depth taking into account both the
geometry and the dynamics of the jet. In the framework of the internal shock
model, we compute lightcurves in different energy bands and the corresponding
spectrum and we show how the limits on the Lorentz factor can be significantly
lowered compared to previous estimates. Our detailed model of the propagation
of high energy photons in GRB outflows is also appropriate to study many other
consequences of gamma-gamma annihilation in GRBs: (i) the gamma-gamma cutoff
transition in a time-integrated spectrum is expected to be closer to a
power-law steepening of the spectrum than to a sharp exponential decay; (ii)
the temporal evolution of the gamma-gamma opacity during a burst favors a delay
between the MeV and GeV light curves; (iii) for complex GRBs, the gamma-gamma
opacity suppresses the shortest time-scale features in high energy light curves
(above 100 MeV). Finally we also consider GRB scenarii where MeV and GeV
photons are not produced at the same location, showing that the gamma-gamma
opacity could be further lowered, reducing even more the constraint on the
minimum Lorentz factor.",1110.6313v1
2012-02-18,"Comment on arXiv:1104.2019, ""Relative locality and the soccer ball problem,"" by Amelino-Camelia et al","It is explained why the argument in arXiv:1104.2019 does not answer the
question how to describe multi-particle states in models with a deformed
Lorentz-symmetry in momentum space.",1202.4066v1
2012-03-08,On The Theory of Time dilation in Chemical Kinetics,"The rates of chemical reactions are not absolute but their magnitude depends
upon the relative speeds of the moving observers. This has been proved by
unifying theories of chemical kinetics, which are transition state theory,
collision theory, RRKM and Marcus theory, with the special theory of
relativity. Boltzmann constant and energy spacing between permitted quantum
levels of molecules are quantum mechanically proved to be Lorentz variant. The
relativistic statistical thermodynamics has been developed to explain
quasiequilibrium existing between reactants and activated complex. The newly
formulated Lorentz transformation of the rate constant from Arrhenius Equation,
of the collision frequency and of the Eyring and Marcus equations renders the
rate law also Lorentz variant. For a moving observer moving at fractions of the
speed of light along the reaction coordinate the transition state possess less
kinetic energy to sweep translation over it. This results in the slower
transformation of reactants into products and in a stretched time frame for the
chemical reaction. Lorentz transformation of the half-life equation explains
time dilation of the half life period of chemical reactions and proves special
theory of relativity and presents theory of relativistic chemical kinetics in
accord with each other. To demonstrate the effectiveness of the present theory,
the enzymatic reaction of methylamine dehydrogenase and radioactive
disintegration of Astatine are considered as numerical examples.",1203.2510v3
2012-08-07,Observer dependence of bubble nucleation and Schwinger pair production,"Pair production in a constant electric field is closely analogous to bubble
nucleation in a false vacuum. The classical trajectories of the pairs are
Lorentz invariant, but it appears that this invariance should be broken by the
nucleation process. Here, we use a model detector, consisting of other
particles interacting with the pairs, to investigate how pair production is
seen by different Lorentzian observers. We focus on the idealized situation
where a constant external electric field is present for an infinitely long
time, and we consider the in-vacuum state for a charged scalar field that
describes the nucleating pairs. The in-vacuum is defined in terms of modes
which are positive frequency in the remote past. Even though the construction
uses a particular reference frame and a gauge where the vector potential is
time dependent, we show explicitly that the resulting quantum state is Lorentz
invariant. We then introduce a ""detector"" particle which interacts with the
nucleated pairs, and show that all Lorentzian observers will see the particles
and antiparticles nucleating preferentially at rest in the detector's rest
frame. Similar conclusions are expected to apply to bubble nucleation in a
sufficiently long lived vacuum. We also comment on certain unphysical aspects
of the Lorentz invariant in-vacuum, associated with the fact that it contains
an infinite density of particles. This can be easily remedied by considering
Lorentz breaking initial conditions.",1208.1335v3
2012-08-15,The Relationship between the Sudden Change of the Lorentz Force and the Magnitude of Associated Flares,"The rapid and irreversible change of photospheric magnetic fields associated
with flares has been confirmed by many recent studies. These studies showed
that the photospheric magnetic fields respond to coronal field restructuring
and turn to a more horizontal state near the magnetic polarity inversion line
(PIL) after eruptions. Recent theoretical work has shown that the change in the
Lorentz force associated with a magnetic eruption will lead to such a field
configuration at the photosphere. The Helioseismic Magnetic Imager has been
providing unprecedented full-disk vector magnetograms covering the rising phase
of the solar cycle 24. In this study, we analyze 18 flares in four active
regions, with GOES X-ray class ranging from C4.7 to X5.4. We find that there
are permanent and rapid changes of magnetic field around the flaring PIL, the
most notable of which is the increase of the transverse magnetic field. The
changes of fields integrated over the area and the derived change of Lorentz
force both show a strong correlation with flare magnitude. It is the first time
that such magnetic field changes have been observed even for C-class flares.
Furthermore, for seven events with associated CMEs, we use an estimate of the
impulse provided by the Lorentz force, plus the observed CME velocity, to
estimate the CME mass. We find that if the time scale of the back reaction is
short, i.e., in the order of 10 s, the derived values of CME mass (10^{15} g)
generally agree with those reported in literature.",1208.3158v1
2012-11-01,A simple model of pointlike spacetime defects and implications for photon propagation,"A model in which pointlike defects are randomly embedded in Minkowski
spacetime is considered. The distribution of spacetime defects is constructed
to be Lorentz-invariant. It does not introduce a preferred reference frame,
because it is based on a sprinkling process. A field-theoretic action for the
photon and a fermion is set up, in which the photon is assumed not to couple to
the defects directly, but via a scalar field. We are interested in signs for
Lorentz violation caused by the spacetime defects, which are expected to reveal
themselves in the photon sector. A modification of the photon dispersion
relation may result as a quantum effect and we compute it at leading order
perturbation theory.
  The outcome of the calculation is that the photon dispersion law remains
conventional, if the defect distribution is dense, homogeneous, and isotropic.
This result sheds some new light on Lorentz violation in the framework of a
small-scale structure of spacetime. It shows that Lorentz invariance can be
preserved even in the presence of a spacetime structure that is supposed to
emerge at the Planck scale. This conclusion has already been drawn on general
grounds in other publications, where the current paper delivers a demonstration
by a direct computation in a simple model.",1211.0084v1
2013-03-06,Hot Electromagnetic Outflows II: Jet Breakout,"We consider the interaction between radiation, matter and a magnetic field in
a compact, relativistic jet. The entrained matter accelerates outward as the
jet breaks out of a star or other confining medium. In some circumstances, such
as gamma-ray bursts (GRBs), the magnetization of the jet is greatly reduced by
an advected radiation field while the jet is optically thick to scattering.
Where magnetic flux surfaces diverge rapidly, a strong outward Lorentz force
develops and radiation and matter begin to decouple. The increase in
magnetization is coupled to a rapid growth in Lorentz factor. We take two
approaches to this problem. The first examines the flow outside the fast
magnetosonic critical surface, and calculates the flow speed and the angular
distribution of the radiation field over a range of scattering depths. The
second considers the flow structure on both sides of the critical surface in
the optically thin regime, using a relaxation method. In both approaches, we
find how the terminal Lorentz factor, and radial profile of the outflow, depend
on the radiation intensity and optical depth at breakout. The effect of bulk
Compton scattering on the radiation spectrum is calculated by a Monte Carlo
method, while neglecting the effects of internal dissipation. The peak of the
scattered spectrum sits near the seed peak if radiation pressure dominates the
acceleration, but is pushed to a higher frequency if the Lorentz force
dominates, and especially if the seed photon cone is broadened by interaction
with a slower component of the outflow.",1303.1554v2
2013-06-15,The spin Hall effect in a quantum gas,"Electronic properties like current flow are generally independent of the
electron's spin angular momentum, an internal degree of freedom present in
quantum particles. The spin Hall effects (SHEs), first proposed 40 years ago,
are an unusual class of phenomena where flowing particles experience
orthogonally directed spin-dependent Lorentz-like forces, analogous to the
conventional Lorentz force for the Hall effect, but opposite in sign for two
spin states. Such spin Hall effects have been observed for electrons flowing in
spin-orbit coupled materials such as GaAs or InGaAs and for laser light
traversing dielectric junctions. Here we observe the spin Hall effect in a
quantum-degenerate Bose gas, and use the resulting spin-dependent Lorentz
forces to realize a cold-atom spin transistor. By engineering a spatially
inhomogeneous spin-orbit coupling field for our quantum gas, we explicitly
introduce and measure the requisite spin-dependent Lorentz forces, in excellent
agreement with our calculations. This atomtronic circuit element behaves as a
new type of velocity-insensitive adiabatic spin-selector, with potential
application in devices such as magnetic or inertial sensors. In addition, such
techniques --- for both creating and measuring the SHE --- are clear
prerequisites for engineering topological insulators and detecting their
associated quantized spin Hall effects in quantum gases. As implemented, our
system realized a laser-actuated analog to the Datta-Das spin transistor.",1306.3579v2
2013-07-19,Using Quantum entanglement to study CP and CPT violations,"We report some general phenomenological results concerning CP and CPT
violations in joint decays of entangled pseudoscalar neutral mesons.",1307.5211v1
2013-07-26,Relativity on two-dimensional spacetimes,"Lorentz transformation on two-dimensional spacetime is obtained without
assumption of linearity. To obtain this, we use the invariance of wave
equations, which is recently proved to be equivalent to the causality
preservation.",1307.6956v1
2013-10-11,First Test of Lorentz Invariance in the Weak Decay of Polarized Nuclei,"A new test of Lorentz invariance in the weak interactions has been made by
searching for variations in the decay rate of spin-polarized 20Na nuclei. This
test is unique to Gamow-Teller transitions, as was shown in the framework of a
recently developed theory that assumes a Lorentz symmetry breaking background
field of tensor nature. The nuclear spins were polarized in the up and down
direction, putting a limit on the amplitude of sidereal variations of the form
|(\Gamma_{up} - \Gamma_{down})| / (\Gamma_{up} + \Gamma_{down}) < 3 * 10^{-3}.
This measurement shows a possible route toward a more detailed testing of
Lorentz symmetry in weak interactions.",1310.3206v2
2013-10-23,Effect of the generalized uncertainty principle on Galilean and Lorentz transformations,"Generalized Uncertainty Principle (GUP) was obtained in string theory and
quantum gravity and suggested the existence of a fundamental minimal length
which, as was established, can be obtained within the deformed Heisenberg
algebra. We use the deformed commutation relations or in classical case
(studied in this paper) the deformed Poisson brackets, which are invariant with
respect to the translation in configurational space. We have found
transformations relating coordinates and times of moving and rest frames of
reference in the space with GUP in the first order over parameter of
deformation. For the non-relativistic case we find the deformed Galilean
transformation which is similar to the Lorentz one written for Euclidean space
with signature $(+,+,+,+)$. The role of the speed of light here plays some
velocity $u$ related to the parameter of deformation, which as we estimate is
many order of magnitude larger than the speed of light $u\simeq 1.2 \times
10^{22} c$. The coordinates of the rest and moving frames of reference for
relativistic particle in the space with GUP satisfy the Lorentz transformation
with some effective speed of light. We estimate that the relative deviation of
this effective speed of light $\tilde c$ from $c$ is ${(\tilde c-c)/ c}\simeq
3.5\times 10^{-45}$. The influence of GUP on the motion of particle and the
Lorentz transformation in the first order over parameter of deformation is
hidden in $1/c^2$ relativistic effects.",1310.6243v1
2014-07-24,On skewon modification of light cone structure,"Electromagnetic media with generic linear response provide a rich class of
Lorentz violation models. In the framework of a general covariant metric-free
approach, we study electromagnetic wave propagation in these media. We define
the notion of an optic tensor and present its unique canonical irreducible
decomposition into the principle and skewon parts. The skewon contribution to
the Minkowski vacuum is a subject that does not arise in the ordinary models of
Lorentz violation based on a modified Lagrangian. We derive the covector
parametrization of the skewon optic tensor and discuss its $U(1)$-gauge
symmetry. We obtain several compact expressions for the contribution of the
principle and skewon optic tensor to the dispersion relation. As an application
of the technique proposed here, we consider the case of a generic skewon tensor
contributed to a simple metric-type principle part. Our main result: Every
solution of the skewon modified Minkowski dispersion relation is necessary
spacelike or null. It provides an extreme violation of the Lorentz symmetry.
The case of the antisymmetric skewon is studied in detail and some new special
cases (electric, magnetic, and degenerate) are discovered. In the case of a
skewon represented by a symmetric matrix, we observe a parametric gap that has
some similarity to the Higgs model. We worked out a set of specific examples
that justify the generic properties of the skewon models and demonstrate the
different types of the Lorentz violation phenomena.",1407.6722v2
2014-09-30,"Uniqueness of solutions to to Navier Stokes equation with small initial data in $L^{3,\infty}(R^3)$","In this short note we address a problem raised in [21], concerning the
uniqueness of solutions to Naiver Stokes equation with small initial data in
$L^{3,\infty}(R^3)$, the Lorentz space. We prove uniqueness for such initial
data.",1409.8382v1
2014-12-08,Pati-Salam model in curved space-time from square root Lorentz manifold,"There is a U(4')\times U(4)-bundle on four-dimensional square root Lorentz
manifold. Then a Pati-Salam model in curved space-time (Lagrangian) and a
gravity theory (Lagrangian) are constructed on square root Lorentz manifold
based on self-parallel transportation principle. An explicit formulation of
Sheaf quantization on this square root Lorentz manifold is shown. Sheaf
quantization is based on superposition principle and construct a linear Sheaf
space in curved space-time. The transition amplitude in path integral
quantization is given which is consistent with Sheaf quantization. All
particles and fields in Standard Model (SM) of particle physics and Einstein
gravity are found in square root metric and the connections of bundle. The
interactions between particles/fields are described by Lagrangian explicitly.
There are few new physics in this model. The gravity theory is Einstein-Cartan
kind with torsion. There are new particles, right handed neutrinos, dark
photon, Fiona, X^{\pm C} and Y^0,Y^1,Y^2,Y_*^1,Y_*^2.",1412.2578v11
2014-12-08,Massive Gravity: A Lorentz-Symmetric Aether,"This is a heuristic introduction to massive gravity based on an analogy with
perfect fluids. I will argue that massive gravity can be thought of as Einstein
gravity in the presence of a medium with unusual properties.",1412.2778v1
2014-12-12,Projected Constraints on Lorentz-Violating Gravity with Gravitational Waves,"Gravitational waves are excellent tools to probe the foundations of General
Relativity in the strongly dynamical and non-linear regime. One such foundation
is Lorentz symmetry, which can be broken in the gravitational sector by the
existence of a preferred time direction, and thus, a preferred frame at each
spacetime point. This leads to a modification in the orbital decay rate of
binary systems, and also in the generation and chirping of their associated
gravitational waves. We here study whether waves emitted in the late,
quasi-circular inspiral of non-spinning, neutron star binaries can place
competitive constraints on two proxies of gravitational Lorentz-violation:
Einstein-\AE{}ther theory and khronometric gravity. We model the waves in the
small-coupling (or decoupling) limit and in the post-Newtonian approximation,
by perturbatively solving the field equations in small deformations from
General Relativity and in the small-velocity/weak-gravity approximation. We
assume a gravitational wave consistent with General Relativity has been
detected with second- and third-generation, ground-based detectors, and with
the proposed space-based mission, DECIGO, with and without coincident
electromagnetic counterparts. Without a counterpart, a detection consistent
with General Relativity of neutron star binaries can only place competitive
constraints on gravitational Lorentz violation when using future,
third-generation or space-based instruments. On the other hand, a single
counterpart is enough to place constraints that are 10 orders of magnitude more
stringent than current binary pulsar bounds, even when using second-generation
detectors. This is because Lorentz violation forces the group velocity of
gravitational waves to be different from that of light, and this difference can
be very accurately constrained with coincident observations.",1412.4132v1
2015-07-30,Boosted Statistical Mechanics,"Based on the fundamental principles of Relativistic Quantum Mechanics, we
give a rigorous, but completely elementary, proof of the relation between
fundamental observables of a statistical system when measured relatively to two
inertial reference frames, connected by a Lorentz transformation.",1508.04800v1
2016-01-29,Lorentz Constraints on Massive Three-Point Amplitudes,"Using the helicity-spinor language we explore the non-perturbative
constraints that Lorentz symmetry imposes on three-point amplitudes where the
asymptotic states can be massive. As it is well known, in the case of only
massless states the three-point amplitude is fixed up to a coupling constant by
these constraints plus some physical requirements. We find that a similar
statement can be made when some of the particles have mass. We derive the
generic functional form of the three-point amplitude by virtue of Lorentz
symmetry, which displays several functional structures accompanied by arbitrary
constants. These constants can be related to the coupling constants of the
theory, but in an unambiguous fashion only in the case of one massive particle.
Constraints on these constants are obtained by imposing that in the UV limit
the massive amplitude matches the massless one. In particular, there is a
certain Lorentz frame, which corresponds to projecting all the massive momenta
along the same null momentum, where the three-point massive amplitude is fully
fixed, and has a universal form.",1601.08113v4
2016-04-06,Abraham-Lorentz-Dirac Equation in 5D Stuekelberg Electrodynamics,"We derive the Abraham-Lorentz-Dirac (ALD) equation in the framework of the
electrodynamic theory associated with Stueckelberg manifestly covariant
canonical mechanics. In this framework, a particle worldline is traced out
through the evolution of an event $x^\mu(\tau)$. By admitting unconstrained
commutation relations between the positions and velocities, the associated
electromagnetic gauge fields are in general dependent on the parameter $\tau$,
which plays the role of time in Newtonian mechanics. Standard Maxwell theory
emerges from this system as a $\tau$-independent equilibrium limit. In this
paper, we calculate the $\tau$-dependent field induced by an arbitrarily
evolving event, and study the long-range radiation part, which is seen to be an
on-shell plane wave of the Maxwell type. Following Dirac's method, we obtain an
expression for the finite part of the self-interaction, which leads to the ALD
equation that generalizes the Lorentz force. This third-order differential
equation is then converted to an integro-differential equation, identical to
the standard Maxwell expression, except for the $\tau$-dependence of the field.
By studying this $\tau$-dependence in detail, we show that field can be removed
from the integration, so that the Lorentz force depends only on the
instantaneous external field and an integral over dynamical variables of the
event evolution. In this form, pre-acceleration of the event by future values
of the field is not present.",1604.01604v1
2016-07-13,Lorentz-violating type-II Dirac fermions in transition metal dichalcogenide PtTe$_2$,"Topological semimetals have recently attracted extensive research interests
as host materials to condensed matter physics counterparts of Dirac and Weyl
fermions originally proposed in high energy physics. These fermions with linear
dispersions near the Dirac or Weyl points obey Lorentz invariance, and the
chiral anomaly leads to novel quantum phenomena such as negative
magnetoresistance. The Lorentz invariance is, however, not necessarily
respected in condensed matter physics, and thus Lorentz-violating type-II Dirac
fermions with strongly tilted cones can be realized in topological semimetals.
Here, we report the first experimental evidence of type-II Dirac fermions in
bulk stoichiometric PtTe$_2$ single crystal. Angle-resolved photoemission
spectroscopy (ARPES) measurements and first-principles calculations reveal a
pair of strongly tilted Dirac cones along the $\Gamma$-A direction under the
symmetry protection, confirming PtTe$_2$ as a type-II Dirac semimetal. The
realization of type-II Dirac fermions opens a new door for exotic physical
properties distinguished from type-I Dirac fermions in condensed matter
materials.",1607.03643v1
2016-07-26,Background Fields and Gravity,"Gravitational theories with fixed background fields break diffeomorphism
invariance. This breaking can be spontaneous or explicit. A brief summary of
the main consequences of these types of breaking is presented.",1607.07714v1
2016-10-10,Approaching a realistic force balance in geodynamo simulations,"Earth sustains its magnetic field by a dynamo process driven by convection in
the liquid outer core. Geodynamo simulations have been successful in
reproducing many observed properties of the geomagnetic field. However, while
theoretical considerations suggest that flow in the core is governed by a
balance between Lorentz force, rotational force and buoyancy (called MAC
balance for Magnetic, Archimedean, Coriolis) with only minute roles for viscous
and inertial forces, dynamo simulations must employ viscosity values that are
many orders of magnitude larger than in the core due to computational
constraints. In typical geodynamo models viscous and inertial forces are not
much smaller than the Coriolis force and the Lorentz force plays a sub-dominant
role. This has led to conclusions that these simulations are viscously
controlled and do not represent the physics of the geodynamo. Here we show by a
direct analysis of the relevant forces that a MAC balance can be achieved when
the viscosity is reduced to values close to the current practical limit.
Lorentz force, buoyancy and the uncompensated (by pressure) part of the
Coriolis force are of very similar strength, whereas viscous and inertia are
smaller by a factor of at least 20 in the bulk of the fluid volume. Compared to
non-magnetic convection at otherwise identical parameters, the dynamo flow is
of larger scale, less invariant parallel to the rotation axis (less
geostrophic) and convection transports twice as much heat, all of which is
expected when the Lorentz force strongly influences the convection properties.",1610.03107v1
2017-08-01,Astroparticle Physics Tests of Lorentz Invariance Violation,"Testing Lorentz invariance is essential as it is one of the pillars of modern
physics. Moreover, its violation is foreseen in several popular Quantum Gravity
models. Several authors study the effects of Lorentz invariance violation (LIV)
in the propagation of ultra-high energy cosmic rays. These particles are the
most energetic events ever detected and therefore represent a promising
framework to test LIV. In this work we present an analytic calculation of the
in-elasticity for any $a+b \rightarrow c+d$ interaction using first order
perturbation in the dispersion relation that violates Lorentz invariance. The
inelasticity can be calculated by solving a third-order polynomial equation
containing: a) the kinematics of the interaction, b) the LIV term for each
particle and c) the geometry of the interaction. We use the inelasticity we
calculate to investigate the proton propagation in the intergalactic media. The
photopion production of the proton interaction with the CMB is taken into
account using the inelasticity and the attenuation length in different LIV
scenarios. We show how the allowed phase space for the photopion production
changes when LIV is considered for the interaction. The calculations presented
here are going to be extended in order to calculated the modified ultra-high
energy cosmic rays spectrum and compare it to the data.",1708.00266v1
2017-08-30,On Holographic Entanglement Density,"We use holographic duality to study the entanglement entropy (EE) of
Conformal Field Theories (CFTs) in various spacetime dimensions $d$, in the
presence of various deformations: a relevant Lorentz scalar operator with
constant source, a temperature $T$, a chemical potential $\mu$, a marginal
Lorentz scalar operator with source linear in a spatial coordinate, and a
circle-compactified spatial direction. We consider EE between a strip or sphere
sub-region and the rest of the system, and define the ""entanglement density""
(ED) as the change in EE due to the deformation, divided by the sub-region's
volume. Using the deformed CFTs above, we show how the ED's dependence on the
strip width or sphere radius, $L$, is useful for characterizing states of
matter. For example, the ED's small-$L$ behavior is determined either by the
dimension of the perturbing operator or by the first law of EE. For
Lorentz-invariant renormalization group (RG) flows between CFTs, the ""area
theorem"" states that the coefficient of the EE's area law term must be larger
in the UV than in the IR. In these cases the ED must therefore approach zero
from below as $L \to \infty$. However, when Lorentz symmetry is broken and the
IR fixed point has different scaling from the UV, we find that the ED often
approaches the thermal entropy density from above, indicating area theorem
violation.",1708.09376v2
2018-11-01,Probing Lorentz violation effects via a laser beam interacting with a high-energy charged lepton beam,"In this work, the conversion of linear polarization of a laser beam to
circular one through its forward scattering by a TeV order charged lepton beam
in the presence of Lorentz violation correction is explored. We calculate the
ratio of circular polarization to linear one (Faraday Conversion phase
$\Delta\phi_{\rm{FC}}$) of the laser beam interacting with either electron or
the muon beam in the framework of the quantum Boltzmann equation.
  Regarding the experimentally available sensitivity to the Faraday conversion
$\Delta\phi_{\rm{FC}}\simeq 10^{-3}-10^{-2}$, we show that the scattering of a
linearly polarized laser beam with energy $k_0\sim 0.1$ eV and an electron/muon
beam with flux $\bar{\epsilon}_{e,\mu}\sim 10^{10}/10^{12}$ TeV cm$^{-2}$
s$^{-1}$ places an upper bound on the combination of lepton sector Lorentz
violation coefficients $c_{\mu\nu}$ components
$(c_{TT}+1.4~c_{(TZ)}+0.25(c_{XX}+c_{YY}+2~c_{ZZ}))$. The obtained bound on the
combination for the electron beam is at the $4.35\times 10^{-15}$ level and for
the muon beam at the $3.9\times 10^{-13}$ level. It should be mentioned that
the laser and charged lepton beams considered here to reach the experimentally
measurable $\Delta\phi_{\rm{FC}}$ are currently available or will be accessible
in the near future. This study provides a valuable supplementary to other
theoretical and experimental frameworks for measuring and constraining Lorentz
violation coefficients.",1811.00486v2
2018-11-02,On the Emergence of Lorentz Invariance and Unitarity from the Scattering Facet of Cosmological Polytopes,"The concepts of Lorentz invariance of local (flat space) physics, and
unitarity of time evolution and the S-matrix, are famously rigid and robust,
admitting no obvious consistent theoretical deformations, and confirmed to
incredible accuracy by experiments. But neither of these notions seem to appear
directly in describing the spatial correlation functions at future infinity
characterizing the ""boundary"" observables in cosmology. How then can we see
them emerge as {\it exact} concepts from a possible ab-initio theory for the
late-time wavefunction of the universe? In this letter we examine this question
in a simple but concrete setting, for the perturbative wavefunction in a class
of scalar field models where an ab-initio description of the wavefunction has
been given by ""cosmological polytopes"". Singularities of the wavefunction are
associated with facets of the polytope. One of the singularities --
corresponding to the ""total energy pole"" -- is well known to be associated with
the flat-space scattering amplitude. We show how the combinatorics and geometry
of this {\it scattering facet} of the cosmological polytope straightforwardly
leads to the emergence of Lorentz invariance and unitarity for the S-matrix.
Unitarity follows from the way boundaries of the scattering facet factorize
into products of lower-dimensional polytopes, while Lorentz invariance follows
from a contour integral representation of the canonical form, which exists for
any polytope, specialized to cosmological polytopes.",1811.01125v1
2018-11-12,Scattering by a three-dimensional object composed of the simplest Lorentz-nonreciprocal medium,"The simplest Lorentz-nonreciprocal medium has the constitutive relations
(${\bf D} =\epso {\bf E} -{\bf \Gamma}\times {\bf H}$ and ${\bf B} =\muo {\bf
H} + {\bf \Gamma}\times{\bf E}$). Scattering by a three-dimensional object
composed of this medium was investigated using the extended boundary condition
method. Scattering by this object in free space must be attributed to non-zero
$\Gamma=\vert\bf \Gamma\vert$. The differential scattering efficiency is immune
to the transformation of the incident toroidal electric field phasor into a
poloidal electric field phasor, or \textit{vice versa}, and a consequence of
this source-invariance is the polarization-state invariance of the differential
scattering efficiency when the irradiating field is a plane wave. Both the
total scattering and forward-scattering efficiencies of an ellipsoid composed
of the simplest Lorentz-nonreciprocal medium are maximum when the plane wave is
incident in a direction {coparallel (but not antiparallel)} to $\bf \Gamma$,
and the backscattering efficiency is minimum when $\bf \Gamma$ is {parallel} to
the incidence direction. The total scattering and the forward-scattering
efficiencies are maximum when the incidence direction is parallel to the
largest semi-axis of the ellipsoid if the incidence direction is coparallel
(but not antiparallel) to $\bf \Gamma$. Lorentz nonreciprocity in an object is
thus intimately connected to the shape of that object in affecting the
scattered field.",1811.04637v1
2019-05-20,The physical conditions of the afterglow implied by MAGIC's sub-TeV observations of GRB 190114C,"The MAGIC observations of late sub-TeV photons from GRB190114C enable us, for
the first time, to determine the details of the emission process in a GRB
afterglow and to pin down the physical parameters, such as the bulk Lorentz
factor and the Lorentz factor of the emitting electrons as well as some of the
microphysical parameters. We find that the sub-TeV emission is an Inverse
Compton radiation produced at the early afterglow stage. Combining the sub-TeV
and X-ray observations we narrow uncertainties in the conditions inside the
emitting zone, almost eliminating them for some parameters. Seventy seconds
after the trigger the forward shock had Lorentz factor $\simeq 100$ and the
electrons producing the observed sub-TeV radiation had a Lorentz factor $\simeq
10^4$, so that the sub-TeV radiation originates from Comptonization of X-ray
photons at the border between Thomson and Klein-Nishina regimes. The inferred
conditions within the emitting zone are at odds with theoretical expectations
unless one assumes moderate (with $\tau \simeq 2$) absorption of sub-TeV
photons inside the source. With this correction the conditions are in good
agreement with predictions of the pair-balance model, but are also acceptable
for generic afterglow model as one of many possibilities. However, the temporal
evolution of the Inverse Compton peak energyis very different in these two
models. This opens a way to discriminate between the models once late-time
detection in the TeV range become available.",1905.08285v2
2013-08-08,"A ""Boosted Fireball"" Model for Structured Relativistic Jets","We present a model for relativistic jets which generates a particular angular
distribution of Lorentz factor and energy per solid angle. We consider a
fireball with specific internal energy E/M launched with bulk Lorentz factor
\gamma_B. This ""boosted fireball"" model is motivated by the phenomenology of
collapsar jets, but is applicable to a wide variety of relativistic flows. In
its center-of-momentum frame the fireball expands isotropically, converting its
internal energy into radially expanding flow with asymptotic Lorentz factor
\eta_0 ~ E/M. In the lab frame the flow is beamed, expanding with Lorentz
factor \Gamma = 2 \eta_0 \gamma_B in the direction of its initial bulk motion
and with characteristic opening angle \theta_0 ~ 1/\gamma_B. The flow is
jet-like with \Gamma \theta_0 ~ 2 \eta_0 such that jets with \Gamma >
1/\theta_0 are naturally produced. The choice \eta_0 ~ \gamma_B ~ 10 yields a
jet with \Gamma ~ 200 on-axis and angular structure characterized by opening
angle \theta_0 ~ 0.1 of relevance for cosmological GRBs, while \gamma_B >~ 1
may be relevant for low-luminosity GRBs. The model produces a family of
outflows, of relevance for different relativistic phenomena with structures
completely determined by \eta_0 and \gamma_B. We calculate the energy per unit
solid angle for the model and use it to compute light curves for comparison
with the widely used top-hat model. The jet break in the boosted fireball light
curve is greatly subdued when compared to the top-hat model because the edge of
the jet is smoother than for a top-hat. This may explain missing jet breaks in
afterglow light curves.",1308.1731v2
2014-03-12,Total lightcone curvatures of spacelike submanifolds in Lorentz-Minkowski space,"We introduce the totally absolute lightcone curvature for a spacelike
submanifold with general codimension and investigate global properties of this
curvature. One of the consequences is that the Chern-Lashof type inequality
holds. Then the notion of lightlike tightness is naturally induced.",1403.2853v1
2017-01-02,Planck-scale constraints on anisotropic Lorentz and CPT invariance violations from optical polarization measurements,"Lorentz invariance is the fundamental symmetry of Einstein's theory of
special relativity, and has been tested to great level of detail. However,
theories of quantum gravity at the Planck scale indicate that Lorentz symmetry
may be broken at that scale motivating further tests. While the Planck energy
is currently unreachable by experiment, tiny residual effects at attainable
energies can become measurable when photons propagate over sufficiently large
distances. The Standard-Model Extension (SME) is an effective field theory
approach to describe low-energy effects of quantum gravity theories. Lorentz
and CPT symmetry violating effects are introduced by adding additional terms to
the Standard Model Lagrangian. These terms can be ordered by the mass dimension
of the corresponding operator, and the leading terms of interest have dimension
d = 5. Effects of these operators are a linear variation of the speed of light
with photon energy, and a rotation of the linear polarization of photons
quadratic in photon energy, as well as anisotropy. We analyzed optical
polarization data from 72 AGN and GRBs and derived the first set of limits on
all 16 coefficients of mass dimension d = 5 of the SME photon sector. Our
constraints imply a lower limit on the energy scale of quantum gravity of
$10^6$ times the Planck energy, severly limiting the phase space for any theory
that predicts a rotation of the photon polarization quadratic in energy.",1701.00437v2
2018-05-06,Sufficient conditions on Liouville type theorems for the 3D steady Navier-Stokes equations,"Our aim is to prove Liouville type theorems for the three dimensional
steady-state Navier-Stokes equations provided the velocity field belongs to
some Lorentz spaces. The corresponding statement contains several known results
as a particular case.",1805.02227v1
2018-05-29,Gradient estimates for problems with Orlicz growth,"We study a general nonlinear elliptic equation in the Orlicz setting with
data not belonging to the dual of the energy space. We provide several
Lorentz-type and Morrey-type estimates for the gradients of solutions under
various conditions on the data.",1805.11326v1
2001-07-12,The indefinite metric problem revisited and chased away,"Attempts to quantize light in a manifestly Lorentz covariant manner fail
because of the indefinite metric problem. Here an error in the interpretation
is uncovered that is at the root of this problem.",0107025v1
2008-07-16,Dissertation: The Cauchy Problem for Membranes,"We show existence and uniqueness for timelike minimal submanifolds in ambient
Lorentz manifolds admitting a time function. The initial value formulation
introduced and the conditions imposed on the initial data are given in purely
geometric terms.",0807.2539v2
2011-11-23,Particle-dependent deformations of Lorentz symmetry,"I here investigate what is arguably the most significant residual challenge
for the proposal of phenomenologically viable ""DSR deformations"" of
relativistic kinematics, which concerns the description of composite particles,
such as atoms. In some approaches to the formalization of possible scenarios
for DSR-deformation of Lorentz symmetry it emerges that composite particles
should have relativistic properties different from the ones of their
constituent ""fundamental particles"", but these previous results provided no
clue as to how the mismatch of relativistic properties could be consistently
implemented. I show that it is possible to implement a fully consistent
DSR-relativistic description of kinematics endowing different types of
particles with suitably different deformed-Lorentz-symmetry properties. I also
contemplate the possibility that some types of particles (or macroscopic
bodies) behave according to completely undeformed special relativity, which in
particular might apply to the DSR description of the macroscopic bodies that
constitute measuring devices (""observers""). The formalization is also
applicable to cases where different fundamental particles have different
relativistic properties, leading to a type of phenomenology which I illustrate
by considering possible applications to the ongoing analyses of the
""Lorentz-symmetry anomaly"" that was recently tentatively reported by the OPERA
collaboration. Some of the new elements here introduced in the formulation of
relativistic kinematics appear to also provide the starting point for the
development of a correspondingly novel mathematical formulation of
spacetime-symmetry algebras.",1111.5643v2
2012-04-11,Lorentz invariance violation and electromagnetic field in an intrinsically anisotropic spacetime,"Recently, Kostelecky [V.A. Kostelecky, Phys. Lett. B 701, 137 (2011)]
proposed that the spontaneous Lorentz invariance violation (sLIV) is related to
Finsler geometry. Finsler spacetime is intrinsically anisotropic and induces
naturally Lorentz invariance violation (LIV). In this paper, the
electromagnetic field is investigated in locally Minkowski spacetime. The
Lagrangian is presented explicitly for the electromagnetic field. It is
compatible with the one in the standard model extension (SME). We show the
Lorentz--violating Maxwell equations as well as the electromagnetic wave
equation. The formal plane wave solution is obtained for the electromagnetic
wave. The speed of light may depend on the direction of light and the lightcone
may be enlarged or narrowed. The LIV effects could be viewed as influence from
an anisotropic media on the electromagnetic wave. In addition, the
birefringence of light will not emerge at the leading order in this model. A
constraint on the spacetime anisotropy is obtained from observations on
gamma--ray bursts (GRBs).",1204.2478v3
2012-04-16,Albert Einstein and the Fizeau 1851 Water Tube Experiment,"In 1895 Hendrik Antoon Lorentz derived the Fresnel dragging coefficient in
his theory of immobile ether and electrons. This derivation did not explicitly
involve electromagnetic theory at all. According to the 1922 Kyoto lecture
notes, before 1905 Einstein tried to discuss Fizeau's experiment ""as originally
discussed by Lorentz"" (in 1895). At this time he was still under the impression
that the ordinary Newtonian law of addition of velocities was unproblematic. In
1907 Max Laue showed that the Fresnel dragging coefficient would follow from a
straightforward application of the relativistic addition theorem of velocities.
This derivation is mathematically equivalent to Lorentz's derivation of 1895.
From 1907 onwards Einstein adopted Laue's derivation. When Robert Shankland
asked Einstein how he had learned of the Michelson-Morley experiment, Einstein
told him that he had become aware of it through the writings of Lorentz, but
only after 1905 had it come to his attention. ""Otherwise"", he said, ""I would
have mentioned it in my paper"". He continued to say that the experimental
results which had influenced him most were stellar aberration and Fizeau's
water tube experiment. ""They were enough"". Indeed the famous Michelson-Morley
experiment is not mentioned in the 1905 relativity paper; but curiously
Einstein did not mention Fizeau's experimental result either, and this is
puzzling in light of the importance of the experiment in Einstein's pathway to
his theory. In this paper I try to discuss this question.",1204.3390v1
2012-04-30,Poincaré's Dynamics of the Electron - A Theory of Relativity?,"Before 1905, Poincar\'e stressed the importance of the method of clocks and
their synchronization, but unlike Einstein, magnet and conductor (asymmetries
in Lorentz's theory regarding the explanation of Faraday's induction) or
chasing a light beam and overtaking it, were not a matter of great concern for
him. In 1905 Poincar\'e elaborated Lorentz's electron theory from 1904 in two
papers entitled ""Sur la dynamique de l'electron"". In May 1905 he sent three
letters to Lorentz at the same time that Albert Einstein wrote his famous May
1905 letter to Conrad Habicht: ""I can promise you in return four works,[...]
The fourth paper is only a rough draft at this point, and is an electrodynamics
of moving bodies"". In the May 1905 letters to Lorentz Poincar\'e presented the
basic equations of his 1905 Dynamics of the Electron. Hence, in May 1905,
Poincar\'e and Einstein both had drafts of papers pertaining to the principle
of relativity. Poincar\'e's draft led to a space-time mathematical theory of
groups at the basis of which stood the postulate of relativity, and Einstein's
draft led to a kinematical theory of relativity. Poincar\'e did not renounce
the ether. He wrote a new law of addition of velocities, but he did not abandon
the tacit assumptions made about the nature of time, simultaneity, and space
measurements implicit in Newtonian kinematics. Although he questioned absolute
time and absolute simultaneity, he did not make new kinematical tacit
assumptions about space and time. He also did not require reciprocity of the
appearances, and therefore did not discover relativity of simultaneity: these
are the main hallmarks of Einstein's special theory of relativity.
Nevertheless, as shown by other writers, Poincar\'e's theory had influenced
later scientists especially Hermann Minkowski.",1204.6576v1
2015-12-22,Operator Constraints for Twist-3 Functions and Lorentz Invariance Properties of Twist-3 Observables,"We investigate the behavior under Lorentz tranformations of perturbative
coefficient functions in a collinear twist-3 formalism relevant for high-energy
observables including transverse polarization of hadrons. We argue that those
perturbative coefficient functions can, {\it a priori}, acquire quite different
yet Lorentz-invariant forms in various frames. This somewhat surprising
difference can be traced back to a general dependence of the perturbative
coefficient functions on lightcone vectors which are introduced by the twist-3
factorization formulae and which are frame-dependent. One can remove this
spurious frame dependence by invoking so-called Lorentz invariance relations
(LIRs) between twist-3 parton correlation functions. Some of those relations
for twist-3 distribution functions were discussed in the literature before. In
this paper we derive the corresponding LIRs for twist-3 fragmentation
functions. We explicitly demonstrate that these LIRs remove the lightcone
vector dependence by considering transverse spin observables in the
single-inclusive production of hadrons in lepton-nucleon collisions, $\ell N\to
hX$. With the LIRs in hand, we also show that twist-3 observables in general
can be written solely in terms of three-parton correlation functions.",1512.07233v2
2016-04-24,Third order variational equation for the free relativistic top,"I proffer a development of some third order equation of motion for the free
relativistic top from the simultaneously imposed assumptions of variationality
and Lorentz symmetry.",1605.02547v1
2016-05-27,Sobolev-Lorentz spaces in the Euclidean setting and counterexamples,"This paper studies the inclusions between different Sobolev-Lorentz spaces
$W^{1,(p,q)}(\Omega)$ defined on open sets $\Omega \subset {\mathbf{R}^n},$
where $n \ge 1$ is an integer, $1<p<\infty$ and $1 \le q \le \infty.$ We prove
that if $1 \le q<r \le \infty,$ then $W^{1,(p,q)}(\Omega)$ is strictly included
in $W^{1,(p,r)}(\Omega).$
  We show that although $H^{1,(p,\infty)}(\Omega) \subsetneq
W^{1,(p,\infty)}(\Omega)$ where $\Omega \subset {\mathbf{R}}^n$ is open and $n
\ge 1,$ there exists a partial converse. Namely, we show that if a function $u$
in $W^{1,(p,\infty)}(\Omega), n \ge 1$ is such that $u$ and its distributional
gradient $\nabla u$ have absolutely continuous $(p,\infty)$-norm, then $u$
belongs to $H^{1,(p,\infty)}(\Omega)$ as well.
  We also extend the Morrey embedding theorem to the Sobolev-Lorentz spaces
$H_{0}^{1,(p,q)}(\Omega)$ with $1 \le n<p<\infty$ and $1 \le q \le \infty.$
Namely, we prove that the Sobolev-Lorentz spaces $H_{0}^{1,(p,q)}(\Omega)$
embed into the space of H\""{o}lder continuous functions on $\overline{\Omega}$
with exponent $1-\frac{n}{p}$ whenever $\Omega \subset {\mathbf{R}}^n$ is open,
$1 \le n<p<\infty,$ and $1 \le q \le \infty.$",1605.08551v3
2016-08-10,Casimir effect between ponderable media as modeled by the standard model extension,"The CPT-even sector of the standard model extension amounts to extending
Maxwell electrodynamics by a gauge invariant term of the form $- \frac{1}{4} (k
_{F}) _{\alpha \beta \mu \nu} F ^{\alpha \beta} F ^{\mu \nu}$, where the
Lorentz-violating (LV) background tensor $(k _{F}) _{\alpha \beta \mu \nu}$
possesses the symmetries of the Riemann tensor. The electrodynamics in
ponderable media is still described by Maxwell equations in matter with
modified constitutive relations which depend on the coefficients for Lorentz
violation. We study the effects of this theory on the Casimir force between two
semi-infinite ponderable media. The Fresnel coefficients characterizing the
vacuum-medium interface are derived, and with the help of these, we compute the
Casimir energy density. At leading-order in the LV coefficients, the Casimir
energy density is numerically evaluated and successfully compared with the
standard result. We also found a variety of intriguing effects, such as a
non-trivial Kerr effect and the Casimir effect between two phases of the
electromagnetic vacuum. We consider a bubble of Lorentz-symmetric (Maxwell)
vacuum embedded in the infinite Lorentz-violating vacuum, and we calculate the
Casimir energy at leading order, which in this case is quadratic in the LV
coefficients. The Casimir force can be positive, zero, or negative, depending
on the relative strengths between the LV coefficients.",1608.03218v1
2016-08-21,New examples of maximal surfaces in Loretnz-Minkowski space,"We use the Bj\""orling problem in Lorentz-Minkowski space to obtain explicit
parametrizations of maximal surfaces containing a circle and a helix. We
investigate the Weierstrass representation of these surfaces.",1608.05944v1
2016-12-10,"Matters of Gravity, The Newsletter of the Division of Gravitational Physics of the American Physical Society, Volume 48, December 2016","DGRAV News: we hear that ...
  DGRAV program at the APS meeting in Washington D.C.
  Obituary:
  Remembering John Stewart
  Conference Reports:
  CPT and Lorentz Symmetry",1612.04184v1
2018-01-16,On axiomatic formulation of gravity and matter field theories with MDRs and Finsler-Lagrange-Hamilton geometry on (co)tangent Lorentz bundles,"We develop an axiomatic geometric approach and provide an unconventional
review of modified gravity theories, MGTs, with modified dispersion relations,
MDRs, encoding Lorentz invariance violations, LIVs, classical and quantum
random effects, anisotropies etc. There are studied Lorentz-Finsler like
theories elaborated as extensions of general relativity, GR, and quantum
gravity, QG, models and constructed on (co) tangent Lorentz bundles, i.e.
(curved) phase spaces or locally anisotropic spacetimes. An indicator of MDRs
is considered as a functional on various type functions depending on phase
space coordinates and physical constants. It determines respective generating
functions and fundamental physical objects (generalized metrics, connections
and nonholonomic frame structures) for relativistic models of Finsler, Lagrange
and/or Hamilton spaces. We show that there are canonical almost symplectic
differential forms and adapted (non) linear connections which allow us to
formulate equivalent almost K\""{a}hler-Lagrange / - Hamilton geometries. This
way, it is possible to unify geometrically various classes of (non) commutative
MGTs with locally anisotropic gravitational, scalar, non-Abelian gauge field,
and Higgs interactions. We elaborate on theories with Lagrangian densities
containing massive graviton terms and bi-connection and bi-metric modifications
which can be modelled as Finsler-Lagrange-Hamilton geometries. An appendix
contains historical remarks on elaborating Finsler MGTs and a summary of
author's results in twenty directions of research on (non) commutative/
supersymmetric Finsler geometry and gravity; nonholonomic geometric flows,
locally anisotropic superstrings and cosmology, etc.",1801.06444v1
2018-01-31,Charging in a Superconducting Vortex Due to the Three Force Terms in Augmented Eilenberger Equations,"We derive augmented Eilenberger equations that incorporate the following
missing force terms: (i) the Lorentz force, (ii) the pair-potential gradient
(PPG) force, and (iii) the pressure difference arising from the slope in the
density of states (DOS). Recently, augmented Eilenberger equations with the
Lorentz and PPG forces have been derived microscopically by studying the Hall
and charging effects in superconductors, but the pressure due to the slope in
the DOS has not yet been considered in augmented Eilenberger equations, despite
phenomenological indications that it is a charging mechanism in a vortex of
type-II superconductors. This newly added pressure is called ""the SDOS
pressure"". We calculate the charging in an isolated vortex of an s-wave
superconductor with a spherical Fermi surface using the augmented Eilenberger
equations incorporating the Lorentz force, PPG force, and SDOS pressure. When
we compare the charge densities due to the three force terms in the augmented
Eilenberger equations, the vortex-core charging due to the SDOS pressure is
larger than that due to the other forces near the superconducting transition
temperature. Thus, when we calculate the charging in an isolated vortex of a
superconductor with a finite slope in the DOS, we should consider not only the
Lorentz and PPG forces but also the SDOS pressure.",1801.10390v2
2018-10-03,Interval topology in contact geometry,"A topology is introduced on spaces of Legendrian submanifolds and groups of
contactomorphisms. The definition is motivated by the Alexandrov topology in
Lorentz geometry.",1810.01642v2
2018-10-22,Optimal estimation of parameters for scalar fields in expanding universe exhibiting Lorentz invariance violation,"We address the optimal estimation of quantum parameters, in the framework of
local quantum estimation theory, for a massive scalar quantum field in the
expanding Robertson-Walker universe exhibiting Lorentz invariance violation
(LIV). The information about the history of the expanding spacetime in the
presence of LIV can be extracted by taking measurements on the entangled state
of particle modes. We find that, in the estimation of cosmological parameters,
the ultimate bounds to the precision of the Lorentz-invariant massive scalar
field can be improved due to the effects of LIV under some appropriate
conditions. We also show that, in the Lorentz-invariant massive scalar field
and massless scalar field due to LIV backgrounds, the optimal precision can be
achieved by choosing the particles with some suitable LIV, cosmological and
field parameters. Moreover, in the estimation of LIV parameter during the
spacetime expansion, we prove that the appropriate momentum mode of field
particles and larger cosmological parameters can provide us a better precision.
Particularly, the optimal precision of the parameters estimation can be
obtained by performing projective measurements implemented by the projectors
onto the eigenvectors of specific probe states.",1810.09120v3
2018-10-18,"In-medium properties of the low-lying strange, charm, and bottom baryons in the quark-meson coupling model","In-medium properties of the low-lying strange, charm, and bottom baryons in
symmetric nuclear matter are studied in the quark-meson coupling (QMC) model.
Results for the Lorentz-scalar effective masses, mean field potentials felt by
the light quarks in the baryons, in-medium bag radii, and the lowest mode bag
eigenvalues are presented for those calculated using the updated data. This
study completes the in-medium properties of the low-lying baryons in symmetric
nuclear matter in the QMC model, for the strange, charm and bottom baryons
which contain one or two strange, one charm or one bottom quarks, as well as at
least one light quark. Highlight is the prediction of the bottom baryon
Lorentz-scalar effective masses, namely, the Lorentz-scalar effective mass of
$\Sigma_b$ becomes smaller than that of $\Xi_b$ at moderate nuclear matter
density, $m^*_{\Sigma_b} < m^*_{\Xi_b}$, although in vacuum $m_{\Sigma_b} >
m_{\Xi_b}$. We study further the effects of the repulsive Lorentz-vector
potentials on the excitation (total) energies of these bottom baryons.",1810.09260v2
2018-10-19,Lorentz-Morrey global bounds for singular quasilinear elliptic equations with measure data,"The aim of this paper is to present the global estimate for gradient of
renormalized solutions to the following quasilinear elliptic problem:
\begin{align*} \begin{cases} -div(A(x,\nabla u)) &= \mu \quad \text{in} \ \
\Omega, \\ u &=0 \quad \text{on} \ \ \partial \Omega, \end{cases} \end{align*}
in Lorentz-Morrey spaces, where $\Omega \subset \mathbb{R}^n$ ($n \ge 2$),
$\mu$ is a finite Radon measure, $A$ is a monotone Carath\'eodory vector valued
function defined on $W^{1,p}_0(\Omega)$ and the $p$-capacity uniform thickness
condition is imposed on the complement of our domain $\Omega$. It is remarkable
that the local gradient estimates has been proved firstly by G. Mingione in
\cite{Mi3} at least for the case $2 \le p \le n$, where the idea for extending
such result to global ones was also proposed in the same paper. Later, the
global Lorentz-Morrey and Morrey regularities were obtained by N.C.Phuc in
\cite{55Ph1} for regular case $p>2 - \frac{1}{n}$. Here in this study, we
particularly restrict ourselves to the singular case $\frac{3n-2}{2n-1}<p\le
2-\frac{1}{n}$. The results are central to generalize our technique of
good-$\lambda$ type bounds in previous work \cite{MP2018}, where the local
gradient estimates of solution to this type of equation was obtained in the
Lorentz spaces. Moreover, the proofs of most results in this paper are
formulated globally up to the boundary results.",1810.09271v2
2019-06-26,The electromagnetic self-force of a uniformly charged spherical ball,"We calculate the electromagnetic self-force of a uniformly charged spherical
ball moving on a rectilinear trajectory, neglecting the Lorentz contraction.",1906.10999v3
2019-07-04,The Lorentz- and CPT-Violating Standard Model Extension in Chiral Perturbation Theory,"Lorentz and CPT violation in hadronic physics must be tied to symmetry
violations at the underlying quark and gluon level. Chiral perturbation theory
provides a method for translating novel operators that may appear in the
Lagrange density for color-charged parton fields into equivalent forms for
effective theories at the meson and baryon levels. We extend the application of
this technique to the study of Lorentz-violating and potentially CPT-violating
operators from the minimal standard model extension. For dimension-4 operators,
there are nontrivial relations between the coefficients of baryon-level
operators related to underlying quark and gluon operators with the same Lorentz
structures. Moreover, in the mapping of the dimension-3 operators from the
quark and gluon level to the hadron level (considered here for the first time),
many of the hadronic observables contain no new low-energy coupling constants
at all, which makes it possible to make direct translations of bounds derived
using experiments on one kind of hadron into bounds in a completely different
corner of the hadronic sector. A notable consequence of this is bounds (at
$10^{-15}$-$10^{-20}$ GeV levels) on differences $a^{\mu}_{B}-a^{\mu}_{B'}$ of
Lorentz and CPT violation coefficients for $SU(3)_{f}$ octet baryons that
differ in their structure by the replacement of a single valance $d$ quark by a
$s$ quark. Never before has there been any proposal for how these kinds of
differences could be constrained.",1907.02490v2
2019-07-22,Boas' problem for Hankel transforms,"Norm equivalences between a function and its Hankel transform are studied
both in the context of weighted Lebesgue spaces with power weights, and in
Lorentz spaces. Boas'-type results involving real-valued general monotone
functions are obtained. Corresponding results for the Fourier transform are
also given.",1907.09253v1
2020-02-04,Bounded Derivations on Uniform Roe Algebras,"We show that if $C_u^*(X)$ is a uniform Roe algebra associated to a bounded
geometry metric space X, then all bounded derivations on $C^*_u(X)$ are inner.",2002.01532v1
2020-02-04,Covariant Quantum Mechanics and Quantum Spacetime,"We present in the article the formulation of a version of Lorentz covariant
quantum mechanics based on a group theoretical construction from a
Heisenberg-Weyl symmetry with position and momentum operators transforming as
Minkowski four-vectors under the Lorentz symmetry. The basic representation is
identified as a coherent state representation, essentially an irreducible
component of the regular representation, with the matching representation of an
extension of the group $C^*$-algebra giving the algebra of observables. The key
feature of the formulation is that it is not unitary but pseudo-unitary,
exactly in the same sense as the Minkowski spacetime representation. Explicit
wavefunction description is given without any restriction of the variable
domains, yet with a finite integral inner product. The associated covariant
harmonic oscillator Fock state basis has all the standard properties in exact
analog to those of a harmonic oscillator with Euclidean position and momentum
operators of any `dimension'. Galilean limit of the Lorentz symmetry and the
classical limit of the Lorentz covariant framework are retrieved rigorously
through appropriate symmetry contractions of the algebra and its
representation, including the dynamics described through the symmetry of the
phase space, given both in terms of real/complex number coordinates and
noncommutative operator coordinates. The latter gives an explicit picture of
the (projective) Hilbert space as a quantum/noncommutative spacetime.",2002.07083v1
2020-04-21,Unraveling the Angular Symmetry of Optical Force in a Solid Dielectric,"The textbook-accepted formulation of electromagnetic force was proposed by
Lorentz in the 19th century, but its validity has been challenged due to
incompatibility with the special relativity and momentum conservation. The
Einstein-Laub formulation, which can reconcile those conflicts, was suggested
as an alternative to the Lorentz formulation. However, intense debates on the
exact force are still going on due to lack of experimental evidence. Here, we
report the first experimental investigation of angular symmetry of optical
force inside a solid dielectric, aiming to distinguish the two formulations.
The experiments surprisingly show that the optical force exerted by a Gaussian
beam has components with the angular mode number of both 2 and 0, which cannot
be explained solely by the Lorentz or the Einstein-Laub formulation. Instead,
we found a modified Helmholtz theory by combining the Lorentz force with
additional electrostrictive force could explain our experimental results. Our
results represent a fundamental leap forward in determining the correct force
formulation, and will update the working principles of many applications
involving electromagnetic forces.",2004.09828v4
2020-12-24,Lorentz groups of cyclotomic extensions,"In this (mostly historical) note we show how a unified Kummer-Artin-Schreier
sequence from [W], [SOS] may be recovered from the relativistic velocity
addition law.",2012.13258v3
2017-11-30,First-order classical Lagrangians for the nonminimal Standard-Model Extension,"In this paper, we derive the general leading-order classical Lagrangian
covering all fermion operators of the nonminimal Standard-Model Extension
(SME). Such a Lagrangian is considered to be the point-particle analog of the
effective field theory description of Lorentz violation that is provided by the
SME. First of all, a suitable Ansatz is made for the Lagrangian of the
spin-degenerate operators $\hat{a}$, $\hat{c}$, $\hat{e}$, and $\hat{f}$ at
leading order in Lorentz violation. The latter is shown to satisfy the set of
five nonlinear equations that govern the map from the field theory to the
classical description. After doing so, the second step is to propose results
for the spin-nondegenerate operators $\hat{b}$, $\hat{d}$, $\hat{H}$, and
$\hat{g}$. Although these are more involved than the Lagrangians for the
spin-degenerate ones, an analytical proof of their validity is viable,
nevertheless. The final step is to combine both findings to produce a generic
Lagrangian for the complete set of Lorentz-violating operators that is
consistent with the known minimal and nonminimal Lagrangians found in the
literature so far. The outcome reveals the leading-order structure of the
classical SME analog. It can be of use for both phenomenological studies of
classical bodies in gravitational fields and conceptual work on explicit
Lorentz violation in gravity. Furthermore, there may be a possible connection
to Finsler geometry.",1711.11169v1
2018-03-25,Internal shocks in microquasar jets with a continuous Lorentz factor modulation,"We perform relativistic hydrodynamic simulations of internal shocks formed in
microquasar jets by continuous variation of the bulk Lorentz factor, in order
to investigate the internal shock model. We consider one-, two-, and flicker
noise 20-mode variability. We observe emergence of a forward-reverse shock
structure for each peak of the Lorentz factor modulation. The high pressure in
the shocked layer launches powerful outflows perpendicular to the jet beam into
the ambient medium. These outflows dominate the details of the jet's kinetic
energy thermalization. They are responsible for mixing between the jet and
surrounding medium and generate powerful shocks in the latter. These results do
not concur with the popular picture of well-defined internal shells depositing
energy as they collide within the confines of the jet, in fact collisions
between internal shells themselves are quite rare in our continuous formulation
of the problem. For each of our simulations, we calculate the internal energy
deposited in the system, the ""efficiency"" of this deposition (defined as the
ratio of internal to total flow energy), and the maximum temperature reached in
order to make connections to emission mechanisms. We probe the dependence of
these diagnostics on the Lorentz factor variation amplitudes, modulation
frequencies, as well as the initial density ratio between the jet and the
ambient medium.",1803.09276v1
2018-06-14,Selection of axial dipole from a seed magnetic field in rapidly rotating dynamo models,"In this study, we investigate preferences of dipolar magnetic structure from
a seed magnetic field in the rapidly rotating spherical shell dynamo models. In
this study, we set up a realistic model to show the effect of the Lorentz force
in the polarity selection. The important results that has come out from our
study is that the magnetic field acts on the flow much before the saturation.
Our study suggests that the growth of the magnetic field is not a kinematic
effect as one might think off, rather a dynamic effect. This dynamic effect
grows as the field generated with time and finally brings the saturation to the
dynamo action. Previous studies show that Lorentz force effect the flow when
Elsasser number more or less 1 and the studies were focused on the saturation
by looking at the time-averaged quantities. However, in this study, we show a
clear effect of the Lorentz force even at Elsasser number of $0.3-0.4$. To show
the effect of the Lorentz force, we did two different simulations, one is a
nonlinear model and another is kinematic model and shows that how a magnetic
field can change the flow structure and by doing that the generated field
changes, while this kind of behavior is not observed in kinematic dynamo
models. This study shows a scale dependent behaviour of the kinetic helicity at
two different spectral range.",1806.05368v1
2018-08-23,Relativity and Synchrotron Radiation: Critical Reexamination of Existing Theory,"Maxwell's equations are valid only in Lorentz frame i.e. in inertial frame
where the Einstein synchronization procedure is used to assign values of the
time coordinate. Einstein time order must be applied and kept in consistent way
in both dynamics and electrodynamics. However, the usual for accelerator
engineering non-covariant treatment of relativistic particle dynamics in a
constant magnetic field looks precisely the same as in non-relativistic
Newtonian dynamics. According to both treatments, the magnetic field is only
capable of altering the direction of motion, but not the speed of an electron.
However, the non-covariant trajectory does not include relativistic kinematics
effects. The covariant electron trajectory is viewed from the Lorentz lab frame
as a result of successive infinitesimal Lorentz transformations. One of the
consequences of non-commutativity of non-collinear Lorentz boosts is a
difference between covariant and non-covariant single particle trajectories in
a constant magnetic field. One can see that this essential point has never
received attention in the physical community. As a result a correction of the
conventional radiation theory is required. In this paper we present a critical
reexamination of existing synchrotron radiation theory. The main emphasis of
this paper is on spontaneous synchrotron radiation from bending magnets and
undulators.",1808.07808v1
2019-08-07,Lorentz forces induce inhomogeneity and fluxes in active systems,"We consider the nonequilibrium dynamics of a charged active Brownian particle
in the presence of a space dependent magnetic field. It has recently been shown
that the Lorentz force induces a particle flux perpendicular to density
gradients, thus preventing a diffusive description of the dynamics. Whereas a
passive system will eventually relax to an equilibrium state, unaffected by the
magnetic field, an active system subject to a spatially varying Lorentz force
settles into a nonequilibrium steady state characterized by an inhomogeneous
density and divergence-free bulk fluxes. A macroscopic flux of charged active
particles is induced by the gradient of the magnetic field only and does not
require additional symmetric breaking such as density or potential gradients.
This stands in marked contrast to similar phenomena in condensed matter such as
the classical Hall effect. In a confined geometry we observe circulating
fluxes, which can be reversed by inverting the direction of the magnetic field.
Our theoretical approach, based on coarse-graining of the Fokker-Planck
equation, yields analytical results for the density, fluxes, and polarization
in the steady state, all of which are validated by direct computer simulation.
We demonstrate that passive tracer particles can be used to measure the
essential effects of the Lorentz force on the active particle bath, and we
discuss under which conditions the effects of the flux could be observed
experimentally.",1908.02577v1
2019-08-13,Lorentz Factor Evolution of an Expanding Jet Shell Observed in Gamma-ray Burst: Case study of GRB 160625B,"The Lorentz factor of a relativistic jet and its evolution during the jet
expansion are difficult to estimate, especially for the jets in gamma-ray
bursts (GRBs). However, it is related to the understanding of jet physics.
Owing to the absorption of two-photon pair production
($\gamma\gamma{\leftrightarrow}e^+e^-$), a high-energy spectral cutoff may
appear in the radiation spectrum of GRBs. We search such kind of high-energy
cutoff in GRB 160625B, which is one of the brightest bursts in recent years. It
is found that the high-energy spectral cutoff is obvious for the first pulse in
the second emission episode of GRB 160625B (i.e., $\sim$186-192 s after the
burst first trigger), which is smooth and well-shaped. Then, we estimate the
Lorentz factor and radiation location of the jet shell associated with the
first pulse in the second emission episode of GRB 160625B. It is found that the
radiation location increases with time. In addition, the Lorentz factor remains
almost constant during the expansion of the jet shell. This reveals that the
magnetization of the jet is low or intermediate in the emission region, event
though the jet could be still Poynting flux dominated at smaller radii to avoid
a bright thermal component in the emission episode.",1908.04641v1
2019-11-10,Einstein's E = mc^2 derivable from Heisenberg's Uncertainty Relations,"Heisenberg's uncertainty relation can be written in terms of the step-up and
step-down operators in the harmonic oscillator representation. It is noted that
the single-variable Heisenberg commutation relation contains the symmetry of
the Sp(2) group which is isomorphic to the Lorentz group applicable to one
time-like dimension and two space-like dimensions, known as the O(2,1) group.
This group has three independent generators. The one-dimensional step-up and
step-down operators can be combined into one two-by-two Hermitian matrix which
contains three independent operators. If we use a two-variable Heisenberg
commutation relation, the two pairs of independent step-up, step-down operators
can be combined into a four-by-four block-diagonal Hermitian matrix with six
independent parameters. It is then possible to add one off-diagonal two-by-two
matrix and its Hermitian conjugate to complete the four-by-four Hermitian
matrix. This off-diagonal matrix has four independent generators. There are
thus ten independent generators. It is then shown that these ten generators can
be linearly combined to the ten generators for the Dirac's two oscillator
system leadingto the group isomorphic to the de Sitter group O(3,2), which can
the be contracted to the inhomogeneous Lorentz group with four translation
generators corresponding to the four-momentum in the Lorentz-covariant world.
This Lorentz-covariant four-momentum is known as Einstein's E = mc^2.",1911.03818v1
2019-12-27,Matters of Gravity: The Newsletter of the Division of Gravitational Physics of the American Physical Society. Number 54. December 2019,"we hear that..., by David Garfinkle
  APS April Meeting, by David Garfinkle
  Gravity: Strings and higher dimensions, by Cynthia Keeler
  The Eighth Meeting on CPT and Lorentz Symmetry, by Jay Tasson",1912.12352v1
2020-03-02,Critical Review of the Scientific and Economic Efficacy of Lithium Lorentz Force Accelerators,"Electromagnetic propulsion technology has been thought to provide a potential
form of future spacecraft propulsion for some time. In contrast to ion
thrusters, which utilize the Coulomb force to accelerate positively charged
species, electromagnetic propulsion systems utilize the Lorentz force to
accelerate all species in a quasi-neutral state, providing significant
technological benefits over ion thrusters. Several forms of electromagnetic
propulsion have been researched and developed, such as the Variable Specific
Impulse Magnetoplasma Rocket, pulsed inductive thrusters, and the electrodeless
plasma thruster. One of the most promising forms of electromagnetic propulsion,
however, has been the magnetoplasmadynamic thruster. Whereas other
electromagnetic propulsion systems provide high specific impulse values but low
thrust capabilities, magnetoplasmadynamic thrusters have demonstrated the
potential for both high specific impulse values and high thrust densities.
However, these thrusters are not without drawbacks and suffer from issues such
as electrode erosion. A proposed subtype of these thrusters, known as the
Lithium Lorentz Force Accelerator, has been shown to address some of these
issues. As is demonstrated in this paper, mission duration is not notably
improved by the use of Lithium Lorentz Force Accelerators except for mission
distances beyond the capabilities of current propulsion technology. It is also
shown that increasing the amount of batteries onboard a spacecraft does not
necessarily decrease mission duration due to the specific power of current
battery technology, which is on the order of 10^3 W/kg, but that new
developments in nuclear energy technology may allow these thrusters to become
efficacious for missions for which current propulsion technology is
insufficient.",2003.00705v3
2020-05-04,Symmetries from Locality. I. Electromagnetism and Charge Conservation,"It is well known that a theory of the (i) Lorentz invariant and (ii) locally
interacting (iii) two degrees of freedom of a massless spin 1 particle, the
photon, leads uniquely to electromagnetism at large distances. In this work, we
remove the assumption of (i) Lorentz boost invariance, but we still demand (ii)
and (iii). We consider several broad classes of theories of spin 1, which in
general explicitly violate Lorentz symmetry. We restrict to the familiar two
degrees of freedom of the photon. We find that most theories lead to
non-locality and instantaneous signaling at a distance. By demanding a mild
form of locality (ii), namely that the tree-level exchange action is manifestly
local, we find that the photon must still be sourced by a conserved charge with
an associated internal symmetry. This recovers the central features of
electromagnetism, although it does not by itself impose Lorentz boost symmetry.
The case of gravitation dramatically improves the final conclusion and is
reported in detail in our accompanying paper Part 2.",2005.01731v3
2020-05-21,On the Lorentz Force and Torque of Solar Photospheric Emerging Magnetic Fields,"Magnetic flux generated and intensified by the solar dynamo emerges into the
solar atmosphere, forming active regions (ARs) including sunspots. Existing
theories of flux emergence suggest that the magnetic flux can rise buoyantly
through the convection zone but is trapped at the photosphere, while its
further rising into the atmosphere resorts to the Parker buoyancy instability.
To trigger such an instability, the Lorentz force in the photosphere needs to
be as large as the gas pressure gradient to hold up an extra amount of mass
against gravity. This naturally results in a strongly non-force-free
photosphere, which is indeed shown in typical idealized numerical simulations
of flux tube buoyancy from below the photosphere into the corona. Here we
conduct a statistical study of the extents of normalized Lorentz forces and
torques in the emerging photospheric magnetic field with a substantially large
sample of SDO/HMI vector magnetograms. We found that the photospheric field has
a rather small Lorentz force and torque on average, and thus is very close to a
force-free state, which is not consistent with theories as well as idealized
simulations of flux emergence. Furthermore, the small extents of forces and
torques seem not to be influenced by the emerging AR's size, the emergence
rate, or the non-potentiality of the field. This result puts an important
constraint on future development of theories and simulations of flux emergence.",2005.10532v1
2020-08-14,Symmetries from Locality. III. Massless Spin 2 Gravitons and Time Translations,"We relax the assumption of time translation and Lorentz boost symmetry in
theories involving massless spin 2 gravitons, while maintaining a basic notion
of locality that there is no instantaneous signaling at a distance. We project
out longitudinal modes, leaving only two degrees of freedom of the graviton.
Our previous work, which assumed time translation symmetry, found that the
Lorentz boost symmetry is required to ensure locality at leading order. In this
work, without assuming time translations or Lorentz boosts, we show that
locality of the exchange action between matter sources demands that massless
spin 2, at leading order, organizes into Einstein-Hilbert plus a Gauss-Bonnet
term with a prefactor that is constrained to be a particular function of time;
while in the matter sector we recover time translation and Lorentz boost
symmetry. Finally, we comment on whether the time dependence of the
Gauss-Bonnet prefactor may be forbidden by going to higher order in the
analysis and we mention that other possibilities are anticipated if graviton
mass terms are included.",2008.06510v3
2020-08-26,A sharp variant of the Marcinkiewicz theorem with multipliers in Sobolev spaces of Lorentz type,"Given a bounded measurable function $\sigma$ on $\mathbb{R}^n$, we let
$T_\sigma $ be the operator obtained by multiplication on the Fourier transform
by $\sigma $. Let $0<s_1\le s_2\le \cdots \le s_n<1$ and $\psi$ be a Schwartz
function on the real line whose Fourier transform $\widehat{\psi}$ is supported
in $[-2,-1/2]\cup[1/2,2]$ and which satisfies $\sum_{j \in \mathbb{Z}}
\widehat{\psi}\left(2^{-j} \xi\right)=1$ for all $\xi \neq 0$. In this work we
sharpen the known forms of the Marcinkiewicz multiplier theorem by finding an
almost optimal function space with the property that, if the function
\begin{equation*} (\xi_1,\dots, \xi_n)\mapsto \prod_{i=1}^n
(I-\partial_i^2)^{\frac {s_i}2} \Big[ \prod_{i=1}^n \widehat{\psi}(\xi_i)
\sigma(2^{j_1}\xi_1,\dots , 2^{j_n}\xi_n)\Big] \end{equation*} belongs to it
uniformly in $j_1,\dots , j_n \in \mathbb Z$, then $T_{\sigma}$ is bounded on $
{L}^p(\mathbb R^n)$ when $ |\frac{1}{p}-\frac{1}{2} | < s_1$ and $1<p<\infty$.
In the case where $s_i\neq s_{i+1}$ for all $i$, it was proved in [Grafakos,
Israel J. Math., to appear] that the Lorentz space $L ^{\frac{1}{s_1},1}
(\mathbb{R}^n) $ is the function space sought. In this work we address the
significantly more difficult general case when for certain indices $i$ we might
have $s_i=s_{i+1}$. We obtain a version of the Marcinkiewicz multiplier theorem
in which the space $L ^{\frac{1}{s_1},1}$ is replaced by an appropriate Lorentz
space associated with a certain concave function related to the number of terms
among $s_2,\dots , s_n$ that equal $s_1$. Our result is optimal up to an
arbitrarily small power of the logarithm in the defining concave function of
the Lorentz space.",2008.11490v1
2020-09-12,Group Theoretical Approach to Pseudo-Hermitian Quantum Mechanics with Lorentz Covariance and $c \rightarrow \infty $ Limit,"We present in the article the formulation of a version of Lorentz covariant
quantum mechanics based on a group theoretical construction from a
Heisenberg-Weyl symmetry with position and momentum operators transforming as
Minkowski four-vectors under the Lorentz symmetry. The basic representation is
identified as a coherent state representation, essentially an irreducible
component of the regular representation, with the matching representation of an
extension of the group $C^*$-algebra giving the algebra of observables. The key
feature of the formulation is that it is not unitary but pseudo-unitary,
exactly in the same sense as the Minkowski spacetime representation. The
language of pseudo-Hermitian quantum mechanics is adopted for a clear
illustration of the aspect, with a metric operator obtained as really the
manifestation of the Minkowski metric on the space of the state vectors.
Explicit wavefunction description is given without any restriction of the
variable domains, yet with a finite integral inner product. The associated
covariant harmonic oscillator Fock state basis has all the standard properties
in exact analog to those of a harmonic oscillator with Euclidean position and
momentum operators of any `dimension'. Galilean limit of the Lorentz symmetry
and the classical limit are retrieved rigorously through appropriate symmetry
contractions of the algebra and its representation, including the dynamics
described through the symmetry of the phase space.",2009.07499v2
2021-04-13,Revisiting a parity violating gravity model without ghost instability: Local Lorentz covariance,"Recently, based on the theory of teleparallel gravity, a simple and ghost
free parity violating gravity model was proposed in [M. Li, H. Rao, and D.
Zhao, J. Cosmol. Astropart. Phys. 11 (2020) 023], where the Weitzenb\""{o}ck
connection was adopted for simplifying the calculations but breaks the local
Lorentz symmetry explicitly. In this paper, we restore the local Lorentz
symmetry of this model by giving up the Weitzenb\""{o}ck condition on the spin
connection. With full local Lorentz covariance, this model is not a pure tetrad
theory any more. We also apply the new version of this model to the universe
with general Friedmann-Robertson-Walker background. This further generalizes
the studies of [M. Li, H. Rao, and D. Zhao, J. Cosmol. Astropart. Phys. 11
(2020) 023] where only the spatially flat background was considered. Through
the investigations of this paper, we confirm the results obtained in [M. Li, H.
Rao, and D. Zhao, J. Cosmol. Astropart. Phys. 11 (2020) 023] and in addition
get some new results.",2104.05917v4
2021-05-17,Ultrahigh-energy photons from LHAASO as probes of Lorentz symmetry violations,"The Large High Altitude Air Shower Observatory~(LHAASO) is one of the most
sensitive gamma-ray detector arrays currently operating at TeV and PeV
energies. Recently the LHAASO experiment detected ultra-high-energy~(UHE;
$E_{\gamma}\gtrsim 100~\mathrm{TeV}$) photon emissions up to $1.4~\mathrm{PeV}$
from twelve astrophysical gamma-ray sources. We point out that the detection of
cosmic photons at such energies can constrain the photon self-decay motivated
by superluminal Lorentz symmetry violation~(LV) to a higher level, thus can put
strong constraints to certain LV frameworks. Meanwhile, we suggest that the
current observation of the PeV-scale photon with LHAASO may provide hints to
permit a subluminal type of Lorentz violation in the proximity of the Planckian
regime, and may be compatible with the light speed variation at the scale of
$3.6\times 10^{17}~\mathrm{GeV}$ recently suggested from gamma-ray burst~(GRB)
time delays. We further propose detecting PeV photons coming from extragalactic
sources with future experiments, based on LV-induced threshold anomalies of
$e^{+}e^{-}$ pair-production, as a crucial test of subluminal Lorentz
violation. We comment that these observations are consistent with a
D-brane/string-inspired quantum-gravity framework, the space-time foam model.",2105.07967v2
2021-05-19,Proving the Lorentz invariance of the entropy and the covariance of thermodynamics,"The standard argument for the Lorentz invariance of the thermodynamic entropy
in equilibrium is based on the assumption that it is possible to perform an
adiabatic transformation whose only outcome is to accelerate a macroscopic
body, keeping its rest mass unchanged. The validity of this assumption
constitutes the very foundation of relativistic thermodynamics and needs to be
tested in greater detail. We show that, indeed, such a transformation is always
possible, at least in principle. The only two assumptions invoked in the proof
are that there is at least one inertial reference frame in which the second law
of thermodynamics is valid and that the microscopic theory describing the
internal dynamics of the body is a field theory, with Lorentz invariant
Lagrangian density. The proof makes no reference to the connection between
entropy and probabilities and is valid both within classical and quantum
physics. To avoid any risk of circular reasoning, we do not postulate that the
laws of thermodynamics are the same in every reference frame, but we obtain
this fact as a direct consequence of the Lorentz invariance of the entropy.",2105.09294v2
2021-06-07,Lorentz violating inflation and the Swampland,"The swampland conjectures from String theory have had very interesting
implications for cosmology and particularly for Inflation. It has been shown
that the single field inflationary models in a GR based cosmology are in
unavoidable tensions with these conjectures, while these single field models
can still be consistent in certain non-trivial inflationary regimes. So it
becomes interesting to see whether there is a way to overcome the issues of the
swampland and single field inflation in an essentially GR based cosmology. We
show that this can indeed be the case and for this, we consider a certain type
of Lorentz violating inflationary scenario. We work out the swampland bounds
for Lorentz violating inflationary models after which show that inflationary
models which would have had otherwise serious tensions with these conjectures
in a usual GR based scenario, can be very tranquil with the criterion in this
regime. For this we take examples of Higgs inflation, radion gauge inflation
and Spontaenous symmetry breaking inflation and show that the bounds imposed by
the swampland on the Lorentz violating parameter can be easily satisfied in
these models.",2106.03578v4
2021-06-10,Constraints on Lorentz invariance violation with multiwavelength polarized astrophysical sources,"Possible violations of Lorentz invariance (LIV) can produce vacuum
birefringence, which results in a frequency-dependent rotation of the
polarization plane of linearly polarized light from distant sources. In this
paper, we try to search for a frequency-dependent change of the linear
polarization angle arising from vacuum birefringence in the spectropolarimetric
data of astrophysical sources. We collect five blazars with multiwavelength
polarization measurements in different optical bands $(UBVRI)$. Taking into
account the observed polarization angle contributions from both the intrinsic
polarization angle and the rotation angle induced by LIV, and assuming that the
intrinsic polarization angle is an unknown constant, we obtain new constraints
on LIV by directly fitting the multiwavelength polarimetric data of the five
blazars. Here we show that the birefringence parameter $\eta$ quantifying the
broken degree of Lorentz invariance is limited to be in the range of
$-8.91\times 10^{-7}$ < $\eta$ < $2.93\times10^{-5}$ at the $2\sigma$
confidence level, which is as good as or represents one order of magnitude
improvement over the results previously obtained from ultraviolet/optical
polarization observations. Much stronger limits can be obtained by future
multiwavelength observations in the gamma-ray energy band.",2106.05733v1
2021-06-20,"Novel, first-principles approach to deriving Electromagnetic field transformations under oblique Lorentz-Boosts and arbitrary Spatial Rotations","The standard classic special relativistic transformation of the
electromagnetic (EM) field under proper Lorentz transformations is revisited.
As to the pure Lorentz-boosts, popular treatments on EM transformation
contemplate ideal geometries generating special static charge and steady
current distributions and in conjunction, invoke parallel and perpendicular (to
the boost-velocity) components of the fields so engendered; the outcomes
subsequently being suitably generalized. We demonstrate ab initio, the EM field
transformation under arbitrary oblique uniform relative boost velocities from a
broader, rigorous yet remarkably lucid perspective, exploiting the antisymmetry
of the EM-field tensor and symmetry of the general Lorentz-boost transformation
preemptively eliminating the labor of performing complicated matrix
multiplications. Gratifyingly, this instructive exercise manifestly encompasses
time varying fields and yields the transformation relations in a
coordinate-free form. Further, the EM field transformation under proper,
instantaneous 3D rotations is demonstrated to transform as a passive rotation
of the coordinate axes, where the electric and magnetic fields transform
independently as purely electric and magnetic fields, respectively. The present
didactical exercise, amenable to be incorporated in graduate courses on
relativistic electrodynamics, should serve as an excellent illustration on how
powerful symmetry arguments simplify the otherwise tedious calculations while
endowing complete generality to the connections obtained.",2106.11768v3
2021-08-27,Electron-proton co-acceleration on relativistic shocks in extreme-TeV blazars,"The multi-wavelength emission from a newly identified population of
`extreme-TeV' blazars, with Compton peak frequencies around 1 TeV, is difficult
to interpret with standard one-zone emission models. Large values of the
minimum electron Lorentz factor and quite low magnetisation values seem to be
required. We propose a scenario where protons and electrons are co-accelerated
on internal or recollimation shocks inside the relativistic jet. In this
situation, energy is transferred from the protons to the electrons in the shock
transition layer, leading naturally to a high minimum Lorentz factor for the
latter. A low magnetisation favours the acceleration of particles in
relativistic shocks. The shock co-acceleration scenario provides additional
constraints on the set of parameters of a standard one-zone lepto-hadronic
emission model, reducing its degeneracy. Values of the magnetic field strength
of a few mG and minimum electron Lorentz factors of 10^3 to 10^4, required to
provide a satisfactory description of the observed spectral energy
distributions of extreme blazars, result here from first principles. While
acceleration on a single standing shock is sufficient to reproduce the emission
of most of the extreme-TeV sources we have examined, re-acceleration on a
second shock appears needed for those objects with the hardest gamma-ray
spectra. Emission from the accelerated proton population, with the same number
density as the electrons but in a lower range of Lorentz factors, is strongly
suppressed. Satisfactory self-consistent representations were found for the
most prominent representatives of this new blazar class.",2108.12271v1
2021-09-14,Carroll contractions of Lorentz-invariant theories,"We consider Carroll-invariant limits of Lorentz-invariant field theories. We
show that just as in the case of electromagnetism, there are two inequivalent
limits, one ""electric"" and the other ""magnetic"". Each can be obtained from the
corresponding Lorentz-invariant theory written in Hamiltonian form through the
same ""contraction"" procedure of taking the ultrarelativistic limit $c
\rightarrow 0$ where $c$ is the speed of light, but with two different
consistent rescalings of the canonical variables. This procedure can be applied
to general Lorentz-invariant theories ($p$-form gauge fields, higher spin free
theories etc) and has the advantage of providing explicitly an action principle
from which the electrically-contracted or magnetically-contracted dynamics
follow (and not just the equations of motion). Even though not manifestly so,
this Hamiltonian action principle is shown to be Carroll invariant. In the case
of $p$-forms, we construct explicitly an equivalent manifestly
Carroll-invariant action principle for each Carroll contraction. While the
manifestly covariant variational description of the electric contraction is
rather direct, the one for the magnetic contraction is more subtle and involves
an additional pure gauge field, whose elimination modifies the Carroll
transformations of the fields. We also treat gravity, which constitutes one of
the main motivations of our study, and for which we provide the two different
contractions in Hamiltonian form.",2109.06708v1
2021-10-22,Annihilating Entanglement Between Cones,"Every multipartite entangled quantum state becomes fully separable after an
entanglement breaking quantum channel acted locally on each of its subsystems.
Whether there are other quantum channels with this property has been an open
problem with important implications for entanglement theory (e.g., for the
distillation problem and the PPT squared conjecture). We cast this problem in
the general setting of proper convex cones in finite-dimensional vector spaces.
The entanglement annihilating maps transform the $k$-fold maximal tensor
product of a cone $C_1$ into the $k$-fold minimal tensor product of a cone
$C_2$, and the pair $(C_1,C_2)$ is called resilient if all entanglement
annihilating maps are entanglement breaking. Our main result is that
$(C_1,C_2)$ is resilient if either $C_1$ or $C_2$ is a Lorentz cone. Our proof
exploits the symmetries of the Lorentz cones and applies two constructions
resembling protocols for entanglement distillation: As a warm-up, we use the
multiplication tensors of real composition algebras to construct a finite
family of generalized distillation protocols for Lorentz cones, containing the
distillation protocol for entangled qubit states by Bennett et al. as a special
case. Then, we construct an infinite family of protocols using solutions to the
Hurwitz matrix equations. After proving these results, we focus on maps between
cones of positive semidefinite matrices, where we derive necessary conditions
for entanglement annihilation similar to the reduction criterion in
entanglement distillation. Finally, we apply results from the theory of Banach
space tensor norms to show that the Lorentz cones are the only cones with a
symmetric base for which a certain stronger version of the resilience property
is satisfied.",2110.11825v2
2021-11-26,Genuine multipartite entanglement and quantum coherence in an electron-positron system: Relativistic covariance,"The last two decades have witnessed an increasing effort of the scientific
community toward pursuing a better framework for quantum resource covariance,
with the focus predominantly posed on quantum entanglement. In this work, we
move the discussion one step further by analyzing the behavior of both genuine
multipartite entanglement and quantum coherence under Lorentz boosts.
Specifically, we conduct a case study for the problem of an electron-positron
pair created in a superposed multipartite pure state. Our approach is different
from the standard treatments also in that we consider all the components of the
four-momentum, thus allowing for an inspection of scenarios wherein
entanglement can be encoded among these degrees of freedom as well. Our
analysis reveals interesting subtleties in this problem, like the fact that
genuine 4-partite entanglement in the lab frame transforms into genuine
8-partite entanglement plus quantum coherence in the perspective of the
Lorentz-boosted frame. Moreover, a given combination of these quantum resources
is shown to form a Lorentz invariant. Although our findings are not able to
determine, via first principles, an information-theoretic Lorentz invariant,
they pave the way for fundamental incursions along this line.",2111.13614v2
2021-12-28,Relativistic quantum field theory of stochastic dynamics in the Hilbert space,"We develop an action formulation of stochastic dynamics in the Hilbert space.
By generalizing the Wiener process into 1+3-dimensional spacetime, we define a
Lorentz-invariant random field. By coupling the random to quantum fields, we
obtain a random-number action which has the statistical spacetime translation
and Lorentz symmetries. The canonical quantization of the theory results in a
Lorentz-invariant equation of motion for the state vector or density matrix. We
derive the path integral formula of $S$-matrix and the diagrammatic rules for
both the stochastic free field theory and stochastic $\phi^4$-theory. The
Lorentz invariance of the random $S$-matrix is strictly proved. We then develop
a diagrammatic technique for calculating the density matrix. Without
interaction, we obtain the exact $S$-matrix and density matrix. With
interaction, we prove a simple relation between the density matrices of
stochastic and conventional $\phi^4$-theory. Our formalism leads to an
ultraviolet divergence which has the similar origin as that in QFT. The
divergence is canceled by renormalizing the coupling strength to random field.
We prove that the stochastic QFT is renormalizable even in the presence of
interaction. In the models with a linear coupling between random and quantum
fields, the random field excites particles out of the vacuum, driving the
universe towards an infinite-temperature state. The number of excited particles
follows the Poisson distribution. The collision between particles is not
affected by the random field. But the signals of colliding particles are
gradually covered by the background excitations caused by random field.",2112.13996v2
2022-03-15,Quasinormal Modes and Hawking Radiation Sparsity of GUP corrected Black Holes in Bumblebee Gravity with Topological Defects,"We have obtained the Generalized Uncertainty Principle (GUP) corrected de
Sitter and anti-de Sitter black hole solutions in bumblebee gravity with a
topological defect. We have calculated the scalar, electromagnetic and
gravitational quasinormal modes for the both vanishing and non-vanishing
effective cosmological constant using Pad\'e averaged sixth order WKB
approximation method. Apart from this, the time evolutions for all three
perturbations are studied, and quasinormal modes are calculated using the time
domain profile. We found that the first order and second order GUP parameters
$\alpha$ and $\beta$, respectively have opposite impacts on the quasinormal
modes. The study also finds that the presence of a global monopole can decrease
the quasinormal frequencies and the decay rate significantly. On the other
hand, Lorentz symmetry violation has noticeable impacts on the quasinormal
frequencies and the decay rate. We have studied the greybody factors, power
spectrum and sparsity of the black hole with the vanishing effective
cosmological constant for all the three perturbations. The presence of Lorentz
symmetry breaking and the GUP parameter $\alpha$ decrease, while other GUP
parameter $\beta$ and the presence of global monopole increase the probability
of Hawking radiation to reach the spatial infinity. The presence of Lorentz
violation can make the black holes less sparse, while the presence of a global
monopole can increase the sparsity of the black holes. Moreover, we have seen
that the black hole area quantization rule is modified by the presence of
Lorentz symmetry breaking.",2203.07594v2
2022-03-15,Kerr-Sen-like Lorentz violating black holes and Superradiance phenomena,"A Kerr-Sen-like black hole solution results from Einstein-bumblebee gravity.
It contains a Lorentz violating (LV) parameter that enters when the bumblebee
field receives vacuum expectation value through a spontaneously breaking of the
symmetry of the classical action. The geometrical structure concerning the
singularity of this spacetime is studied with reference to the parameters
involved in the Kerr-Sen-like metric. We introduce this Einstein-bumblebee
modified gravity to probe the role of spontaneous Lorentz violation on the
superradiance scattering phenomena and the instability associated with it. We
observe that for the low-frequency range of the scalar wave the superradiance
scattering gets enhanced when the Lorentz-violating parameter $\ell$ takes the
negative values and it reduces when values of $\ell$ are positive. The study of
the black hole bomb issue reveals that for the negative values of $\ell$, the
parameter space of the scalar field instability increase prominently, however,
for its positive values, it shows a considerable reduction. We also tried to
put constraints on the parameters contained in the Kerr-Sen-like black hole by
comparing the deformation of the shadow produced by the black hole parameters
with the observed deviation from circularity and the angular deviation from the
$M87*$ data.",2203.08099v1
2022-04-28,PDM Klein-Gordon particles in Gödel-type Som-Raychaudhuri cosmic string spacetime background,"In G\""odel-type Som-Raychaudhuri (SR) cosmic string spacetime background, we
re-cycle the Klein-Gordon (KG) oscillators and report their correct exact
solutions. We argue that the mathematical collapse of the KG-equation into the
2-dimensional radial Schr\""odinger-like oscillator does not yield that the
parametric characterizations of one is inherited by the other. The angular
frequency (positive) in the Schr\""odinger case is replaced by an irrational
frequency-like (positive and negative) in the KG-case. Inheriting the
Schr\""odinger oscillator's parametric characterizations implies that at least
half of the spectra (the negative part) is lost in the process. We also
introduce KG-oscillators in pseudo-G\""odel SR-type spacetime that admit
invariance and isospectrality with those in G\""odel SR-type spacetime
background. We introduce position-dependent mass (PDM) settings to KG-particles
in 4-vector and scalar Lorentz potentials in magnetic field in the G\""odel
SR-type spacetime background. Four illustrative examples of fundamental nature
are discussed and their exact or conditionally exact solvability are reported.
Amongst are, a PDM KG-Coulombic particle in 4-vector and scalar Coulombic
Lorentz potentials in magnetic field, a PDM KG-Coulombic particle in 4-vector
and scalar Coulombic Lorentz potentials in magnetic field at zero vorticity, a
PDM KG-Coulombic particle in equally mixed 4-vector and scalar Coulombic
Lorentz potentials in magnetic field, and a quasi-free PDM KG-oscillator. We
also emphasis that the biconfluent Heun polynomial approach, to the effective
oscillator plus Cornell type potential, yields conditionally exact solvability
that paralyzes the solution from collapsing into that of pure Coulombic one.",2204.13298v1
2022-05-05,Regularity criteria and Liouville Theorem for 3D inhomogeneous Navier-Stokes flows with vacuum,"In this paper, we investigate the 3D inhomogeneous Navier-Stokes flows with
vacuum, and obtain regularity criteria and Liouville type theorems in the
Lorentz space if a smooth solution $(\rho, \mathbf{u})$ satisfies suitable
conditions.",2205.02378v1
2022-06-30,Borderline global regularity for nonuniformly elliptic systems,"We establish sharp global regularity results for solutions to nonhomogeneous,
nonunifomrly elliptic systems with zero boundary conditions. In particular, we
obtain everywhere Lipschitz continuity under borderline Lorentz assumptions on
the forcing term, thus positively settling the optimality issue raised in
\cite{bdms}.",2206.15330v1
2022-07-21,SME Gravity: Structure and Progress,"This proceedings contribution outlines the current structure of the gravity
sector of the Standard-Model Extension and summaries recent progress in
gravitational wave analysis.",2207.10515v1
2022-08-14,"Entanglement, CPT and neutral kaons","Direct tests of T, CP, CPT symmetries in transitions using entangled neutral
kaons produced at a $\phi$-factory are briefly reviewed.",2208.06789v1
2022-08-18,Sobolev-Lorentz spaces with an application to the inhomogeneous biharmonic NLS equation,"We consider the Cauchy problem for the inhomogeneous biharmonic nonlinear
Schr\""{o}dinger (IBNLS) equation \[iu_{t} +\Delta^{2} u=\lambda
|x|^{-b}|u|^{\sigma}u,\;u(0)=u_{0} \in H^{s} (\mathbb R^{d}),\] where
$\lambda\in \mathbb R$, $d\in \mathbb N$, $0\le
s<\min\left\{2+\frac{d}{2},d\right\}$, $0<b<\min \left\{4,\; d-s,\;
2+\frac{d}{2}-s \right\}$ and $0<\sigma\le \sigma_{c}(s)$ with $\sigma<\infty$.
Here $\sigma_{c}(s)=\frac{8-2b}{d-2s}$ if $s<\frac{d}{2}$, and
$\sigma_{c}(s)=\infty$ if $s\ge \frac{d}{2}$. First, we give some remarks on
Sobolev-Lorentz spaces and extend the chain rule under Lorentz norms for the
fractional Laplacian $(-\Delta)^{s/2}$ with $s\in (0,1]$ established by
[Discrete Contin. Dyn. Syst. 41 (2021) 5409-5437] to any $s>0$. Applying this
estimate and the contraction mapping principle based on Strichartz estimates in
Lorentz spaces, we then establish the local well-posedness in $H^{s}$ for the
IBNLS equation in both of subcritical case $\sigma<\sigma_{c}(s)$ and critical
case $\sigma=\sigma_{c}(s)$. We also prove that the IBNLS equation is globally
well-posed in $H^{s}$, if the initial data is sufficiently small and
$\frac{8-2b}{d}\le \sigma\le \sigma_{c}(s)$ with $\sigma<\infty$.",2208.08657v1
2022-11-21,Hardy--Littlewood fractional maximal operators on homogeneous trees,"We study the mapping properties of the Hardy--Littlewood fractional maximal
operator between Lorentz spaces of the homogeneous tree and discuss the
optimality of all the results.",2211.11871v1
2023-02-09,Lorentz Equivariant Model for Knowledge-Enhanced Hyperbolic Collaborative Filtering,"Introducing prior auxiliary information from the knowledge graph (KG) to
assist the user-item graph can improve the comprehensive performance of the
recommender system. Many recent studies show that the ensemble properties of
hyperbolic spaces fit the scale-free and hierarchical characteristics exhibited
in the above two types of graphs well. However, existing hyperbolic methods
ignore the consideration of equivariance, thus they cannot generalize symmetric
features under given transformations, which seriously limits the capability of
the model. Moreover, they cannot balance preserving the heterogeneity and
mining the high-order entity information to users across two graphs. To fill
these gaps, we propose a rigorously Lorentz group equivariant
knowledge-enhanced collaborative filtering model (LECF). Innovatively, we
jointly update the attribute embeddings (containing the high-order entity
signals from the KG) and hyperbolic embeddings (the distance between hyperbolic
embeddings reveals the recommendation tendency) by the LECF layer with Lorentz
Equivariant Transformation. Moreover, we propose Hyperbolic Sparse Attention
Mechanism to sample the most informative neighbor nodes. Lorentz equivariance
is strictly maintained throughout the entire model, and enforcing equivariance
is proven necessary experimentally. Extensive experiments on three real-world
benchmarks demonstrate that LECF remarkably outperforms state-of-the-art
methods.",2302.04545v2
2023-03-05,A Lorentz invariant sharp Sobolev inequality on the circle,"We prove the following sharp Sobolev inequality on the circle
$$\int_{\mathbb{S}^1} [4(v')^2 - v^2] \mathrm{d} \theta \geq -
\frac{4\pi^2}{\int_{\mathbb{S}^1} v^{-2} \mathrm{d} \theta},$$ with the
equality being achieved when $v^{-2} (\theta) = \frac{k\sqrt{1-\alpha^2}}{1+
\alpha \cos(\theta - \theta_o)}$where$k>0$, $\alpha \in (-1,1)$, $\theta_0 \in
\mathbb{R}$. If $v$ vanishes somewhere on the circle, then $$4
\int_{\mathbb{S}^1} (v')^2 \mathrm{d} \theta \geq\int_{\mathbb{S}^1} v^2
\mathrm{d} \theta.$$ The basic tools to prove the inequality are the
rearrangement inequality on the circle and the variational method. We
investigate the variational problem of the functional $\mathcal{F}[v] =
\int_{\mathbb{S}^1} [4(v')^2 - v^2] \mathrm{d} \theta$ under the constraint
$\int_{\mathbb{S}^1} v^{-2} \mathrm{d} \theta = 2\pi$. An important geometric
insight of the functional $\mathcal{F}$ is that it is invariant under the
Lorentz group, since $\mathcal{F}[v]$ is the integral of the product of two
null expansions of a spacelike curve parameterised by the function $v^{-2}$ in
a lightcone in $3$-dim Minkowski spacetime. The global minimiser of
$\mathcal{F}$ under the constraint is simply given by the spacelike plane
section of the lightcone. We introduce a method which combines the symmetric
decreasing rearrangement and the Lorentz transformation. This method isnot
confined to the scope of this paper, but is applicable to other Lorentz
invariant variational problems on $\mathbb{S}^{n}, n \geq 1$. As an example, we
sketch a proof of the sharp Sobolev inequality on $\mathbb{S}^n, n\geq 3$ by
this method.",2303.02709v1
2023-03-24,Unveiling the mechanism for the rapid acceleration phase in a solar eruption,"Two major mechanisms have been proposed to drive the solar eruptions: the
ideal magnetohydrodynamic instability and the resistive magnetic reconnection.
Due to the close coupling and synchronicity of the two mechanisms, it is
difficult to identify their respective contribution to solar eruptions,
especially to the critical rapid acceleration phase. Here, to shed light on
this problem, we conduct a data-driven numerical simulation for the flux rope
eruption on 2011 August 4, and quantify the contributions of the upward exhaust
of the magnetic reconnection along the flaring current sheet and the work done
by the large-scale Lorentz force acting on the flux rope. Major simulation
results of the eruption, such as the macroscopic morphology, early kinematics
of the flux rope and flare ribbons, match well with the observations. We
estimate the energy converted from the magnetic slingshot above the current
sheet and the large-scale Lorentz force exerting on the flux rope during the
rapid acceleration phase, and find that (1) the work done by the large-scale
Lorentz force is about 4.6 times higher than the former, and (2) decreased
strapping force generated by the overlying field facilitates the eruption.
These results indicate that the large-scale Lorentz force plays a dominant role
in the rapid acceleration phase for this eruption.",2303.14050v1
2023-05-10,Regularizing properties of n-Laplace systems with antisymmetric potentials in Lorentz spaces,"We show continuity of solutions $u \in W^{1,n}(B^n,\mathbb{R}^N)$ to the
system \[
  -{\rm div} (|\nabla u|^{n-2} \nabla u) = \Omega \cdot |\nabla u|^{n-2} \nabla
u \] when $\Omega$ is an $L^n$-antisymmetric potential -- and additionally
satisfies a Lorentz-space assumption.
  To obtain our result we study a rotated n-Laplace system \[
  -{\rm div} (Q|\nabla u|^{n-2} \nabla u) = \tilde{\Omega} \cdot |\nabla
u|^{n-2} \nabla u, \] where $Q \in W^{1,n}(B^n,SO(N))$ is the Coulomb gauge
which ensures improved Lorentz-space integrability of $\tilde{\Omega}$. Because
of the matrix-term $Q$, this system does not fall directly into
Kuusi-Mingione's vectorial potential theory. However, we adapt ideas of their
theory together with Iwaniec' stability result to obtain
$L^{(n,\infty)}$-estimates of the gradient of a solution which, by an iteration
argument leads to the regularity of solutions. As a corollary of our argument
we see that $n$-harmonic maps into manifolds are continuous if their gradient
belongs to the Lorentz-space $L^{(n,2)}$ -- which is a trivial and optimal
assumption if $n=2$, and the weakest assumption to date for the regularity of
critical $n$-harmonic maps, without any added differentiability assumption. We
also discuss an application to H systems.",2305.05961v2
2023-07-31,Explainable Equivariant Neural Networks for Particle Physics: PELICAN,"PELICAN is a novel permutation equivariant and Lorentz invariant or covariant
aggregator network designed to overcome common limitations found in
architectures applied to particle physics problems. Compared to many approaches
that use non-specialized architectures that neglect underlying physics
principles and require very large numbers of parameters, PELICAN employs a
fundamentally symmetry group-based architecture that demonstrates benefits in
terms of reduced complexity, increased interpretability, and raw performance.
We present a comprehensive study of the PELICAN algorithm architecture in the
context of both tagging (classification) and reconstructing (regression)
Lorentz-boosted top quarks, including the difficult task of specifically
identifying and measuring the $W$-boson inside the dense environment of the
Lorentz-boosted top-quark hadronic final state. We also extend the application
of PELICAN to the tasks of identifying quark-initiated vs.~gluon-initiated
jets, and a multi-class identification across five separate target categories
of jets. When tested on the standard task of Lorentz-boosted top-quark tagging,
PELICAN outperforms existing competitors with much lower model complexity and
high sample efficiency. On the less common and more complex task of 4-momentum
regression, PELICAN also outperforms hand-crafted, non-machine learning
algorithms. We discuss the implications of symmetry-restricted architectures
for the wider field of machine learning for physics.",2307.16506v4
2023-08-03,Unifying heat transport model for the transition between buoyancy-dominated and Lorentz-force-dominated regimes in quasistatic magnetoconvection,"In magnetoconvection, the flow of electromagnetically conductive fluid is
driven by a combination of buoyancy forces, which create the fluid motion due
to thermal expansion and contraction, and Lorentz forces, which distort the
convective flow structure in the presence of a magnetic field. The differences
in the global flow structures in the buoyancy-dominated and
Lorentz-force-dominated regimes lead to different heat transport properties in
these regimes, reflected in distinct dimensionless scaling relations of the
global heat flux (Nusselt number $\textrm{Nu}$) versus the strength of buoyancy
(Rayleigh number $\textrm{Ra}$) and electromagnetic forces (Hartmann number
$\textrm{Ha}$). Here, we propose a theoretical model for the transition between
these two regimes for the case of a quasistatic vertical magnetic field applied
to a convective fluid layer confined between two isothermal, a lower warmer and
an upper colder, horizontal surfaces. The model suggests that the scaling
exponents $\gamma$ in the buoyancy-dominated regime,
$\textrm{Nu}\sim\textrm{Ra}^\gamma$, and $\xi$ in the Lorentz-force-dominated
regime, $\textrm{Nu}\sim(\textrm{Ha}^{-2}\textrm{Ra})^\xi$, are related as
$\xi=\gamma/(1-2\gamma)$, and the onset of the transition scales with
$\textrm{Ha}^{-1/\gamma}\textrm{Ra}$. These theoretical results are supported
by our Direct Numerical Simulations for $10\leq \textrm{Ha}\leq2000$, Prandtl
number $\textrm{Pr}=0.025$ and $\textrm{Ra}$ up to $10^9$ and data from the
literature.",2308.01748v1
2023-08-13,On embedding theorems of spaces of functions with mixed logarithmic smoothness,"The article considers the Lorentz space $L_{p,\tau}(\mathbb{T}^{m})$, $2\pi$
of periodic functions of many variables and spaces with mixed logarithmic
smoothness. Equivalent norms of a space with mixed logarithmic smoothness are
found and embedding theorems are proved.",2308.06737v1
2023-09-06,Moment of Inertia for Axisymmetric Neutron Stars in the Standard-Model Extension,"We develop a consistent approach to calculate the moment of inertia (MOI) for
axisymmetric neutron stars (NSs) in the Lorentz-violating Standard-Model
Extension (SME) framework. To our knowledge, this is the first relativistic MOI
calculation for axisymmetric NSs in a Lorentz-violating gravity theory other
than deformed, rotating NSs in the General Relativity. Under Lorentz violation,
there is a specific direction in the spacetime and NSs get stretched or
compressed along that direction. When a NS is spinning stationarily along this
direction, a conserved angular momentum and the concept of MOI are well
defined. In the SME framework, we calculate the partial differential equation
governing the rotation and solve it numerically with the finite element method
to get the MOI for axisymmetric NSs caused by Lorentz violation. Besides, we
study an approximate case where the correction to the MOI is regarded solely
from the deformation of the NS and compare it with its counterpart in the
Newtonian gravity. Our formalism and the numerical method can be extended to
other theories of gravity for static axisymmetric NSs.",2309.02871v2
2023-09-30,Regularity criteria of 3D generalized magneto-micropolar fluid system in terms of the pressure,"This work focuses on regularity criteria of 3D generalized magneto-micropolar
fluid system in terms of the pressure in Lorentz spaces inspired by the recent
works in \cite{FS22} and \cite{LN22}.",2310.00217v1
2023-10-02,Hawking Radiation in Lorentz Violating Gravity: A Tale of Two Horizons,"Since their proposal, Lorentz violating theories of gravity have posed a
potential threat to black hole thermodynamics, as superluminal signals appeared
to be incompatible with the very black hole notion. Remarkably, it was soon
realized that in such theories causally disconnected regions of space-time can
still exist thanks to the presence of universal horizons: causal barriers for
signals of arbitrary high speed. Several investigations, sometimes with
contrasting results, have been performed so to determine if these horizons can
be associated with healthy thermodynamic properties similar to those associated
with Killing horizons in General Relativity. In this work we offer what we deem
to be the final picture emerging from this and previous studies. In summary we
show that: 1) there is a thermal, and most of all species-independent, emission
associated to universal horizons, determined by their surface gravity; 2) due
to the modified dispersion relation of the matter fields, the low energy part
of the emitted spectrum is affected by the presence of the Killing horizon, in
a way similar to an effective refractive index, leading at low energies (w.r.t.
the Lorentz breaking scale) to an emission that mimics a standard Hawking
spectrum (i.e. one determined by the Killing horizon surface gravity); 3) the
whole picture is compatible with a globally well defined vacuum state i.e. an
Unruh state associated with preferred observers, which however at very low
energies it is basically indistinguishable from the standard Unruh vacuum
associated to metric free-falling observers. One can then conclude that Hawking
radiation is remarkably resilient even within the context of gravitational
theories entailing the breakdown of local Lorentz invariance.",2310.01472v1
2023-11-11,The universal cover of the real projective line,"We construct an interesting topological cover of the multiplicative group of
the real line, related to Tate's elliptic curve with $q = e^\pi$. We use the
language of homological algebra, 2D Lorentz geometry and high-school
trigonometry; the intent is expository but the suggested applications may be
unusual.",2311.06676v1
2023-11-21,Investigating the Lorentz Invariance Violation effect using different cosmological backgrounds,"Familiar concepts in physics, such as Lorentz symmetry, are expected to be
broken at energies approaching the Planck energy scale as predicted by several
quantum-gravity theories. However, such very large energies are unreachable by
current experiments on Earth. Current and future Cherenkov telescope facilities
may have the capability to measure the accumulated deformation from Lorentz
symmetry for photons traveling over large distances via energy-dependent time
delays. One of the best natural laboratories to test Lorentz Invariance
Violation~(LIV) signatures are Gamma-ray bursts~(GRBs). The calculation of time
delays due to the LIV effect depends on the cosmic expansion history. In most
of the previous works calculating time lags due to the LIV effect, the standard
$\Lambda$CDM (or concordance) cosmological model is assumed. In this paper, we
investigate whether the LIV signature is significantly different when assuming
alternatives to the $\Lambda$CDM cosmological model. Specifically, we consider
cosmological models with a non-trivial dark-energy equation of state ($w \neq
-1$), such as the standard Chevallier-Polarski-Linder~(CPL) parameterization,
the quadratic parameterization of the dark-energy equation of state, and the
Pade parameterizations. We find that the relative difference in the predicted
time lags is small, of the order of at most a few percent, and thus likely
smaller than the systematic errors of possible measurements currently or in the
near future.",2311.12620v1
2023-12-14,Constraints on Lorentz invariance violation from the LHAASO observation of GRB 221009A,"In some quantum gravity (QG) theories, Lorentz symmetry may be broken above
the Planck scale. The Lorentz invariance violation (LIV) may induce observable
effects at low energies and be detected at high energy astrophysical
measurements. The Large High Altitude Air Shower Observatory(LHAASO) has
detected the onset, rise, and decay phases of the afterglow of GRB 221009A,
covering a wide energy range of photons approximately from $0.2$ to $18$ TeV.
This observation provides an excellent opportunity to study the Lorentz
invariance violation effect. In this study, we simultaneously utilize the data
from the KM2A and WCDA detectors of LHAASO, and apply two event by event
methods, namely the pair view method and maximum likelihood method, to
investigate LIV. We obtain stringent constraints on the QG energy scale. For
instance, through the maximum likelihood method, we determine the 95$\%$
confidence level lower limits to be $E_{QG,1} > 14.7 (6.5)\times 10^{19}$GeV
for the subluminal (superluminal) scenario of $n = 1$, and $E_{QG,2} > 12.0
(7.2)\times 10^{11}$GeV for the subluminal (superluminal) scenario of $n = 2$.
We find that the rapid rise and slow decay behaviors of the afterglow can
impose strong constraints on the subluminal scenario, while the constraints are
weaker for the superluminal scenario.",2312.09079v1
2023-12-18,A Special Lorentz Violation Model and a Special Rainbow Function,"In order to characterize the common feature of the general Lorentz violation
models that the local speed of light is variable at ultrahigh energy scale, we
introduced a parameter n to characterize the variation of the speed of light
between inertial systems. And in order not to violate some fundamental
principles and experiments' results, some constraints were imposed on n. Then a
coordinate transformation with the parameter n, which meets the symmetry of
inertial systems, was naturally obtained. But just to satisfy the symmetry of
inertial systems, the expression for n cannot be determined. Inspired by the
idea of DSR model, we then discussed a specific expression for n that makes the
particle's energy have a limit rather than be infinite derived from the Lorentz
model. We found that the modified dispersion relation corresponding to the
specific expression for n is deeply associated with the general formula of
dispersion relation from the DSR. The motivation of introducing such a
parameter n was also discussed. Finally, we discussed the possible LIV effects
from astrophysical observations in GRB events and photon annihilation events.
Using the data from GRB 190114C we investigated the special dispersion relation
obtained in this paper and found that it appears to fit these data better than
the two models corresponding to the first or second order approximation of the
general formula of dispersion relation. And similar to the other Lorentz
violation models corresponding to the subluminal case, the modified dispersion
relation obtained in this paper can also result in increasing the energy
threshold of photon annihilation reaction, which is expected to be verified by
the future energetic photons events.",2312.14176v2
1995-02-16,Lyman alpha Emission from High-Redshift Galaxies,"We summarise the results of a deep search for Lyman alpha emission from
star-forming regions associated with damped Lyman alpha absorption systems and
conclude that the Lyman alpha luminosity of high redshift galaxies is generally
less than 10^(42) erg/s . We also present a newly discovered case, in the field
of the QSO Q2059-360, where the emission is unusually strong, possibly because
the damped system is close in redshift to the QSO.",9502076v1
1995-10-12,Limits on diffusive shock acceleration in dense and incompletely ionised media,"The limits imposed on diffusive shock acceleration by upstream ion-neutral
Alfven wave damping, and by ionisation and Coulomb losses of low energy
particles, are calculated. Analytic solutions are given for the steady upstream
wave excitation problem with ion-neutral damping and the resulting escaping
upstream flux calculated. The time dependent problem is discussed and numerical
solutions presented. Finally the significance of these results for possible
observational tests of shock acceleration in supernova remnants is discussed.",9510066v2
1995-11-28,Damping of GRR instability by direct URCA reactions,"The role of direct URCA reactions in damping of the gravitational radiation
driven instability is discussed. The temperature at which bulk viscosity
suppresses completely this instability is calculated.
  The results are obtained analytically using recent calculations performed in
the case of bulk viscosity due to the modified URCA processes (Lindblom 1995;
Yoshida & Eriguchi 1995).
  The bulk viscosity caused by direct URCA reactions is found to reduce
significantly the region of temperatures and rotation frequencies where a
neutron star is subject to GRR instability.",9511136v1
1997-10-31,Abundances in Damped Lyman-alpha Systems and Chemical Evolution of High Redshift Galaxies,"Recent abundance measurements in damped Lyman-alpha galaxies, supplemented
with unpublished Keck observations, are discussed. The metallicity distribution
with cosmic time is examined for clues about the degree of enrichment, the
onset of initial star formation, and the nature of the galxies. The relative
abundances of the elements are compared with the abundnce pattern in Galactic
halo stars and in the Sun, taking into account of the effects of dust
depletion, in order to gain insight into the stellar processes and the time
scales by which the enrichment occurred.",9710370v1
1998-05-08,Exploring the Damped Lyman-alpha Clouds with AXAF,"The High Energy Transmission Grating (HETG) Spectrometer on the Advanced
X-ray Astrophysics Facility (AXAF) (scheduled for launch in August, 1998) will
provide a new tool for the study of absorption in the X-ray spectra of high
redshift quasars due to the material along the line of sight. In this paper we
try to explore the possibility of using AXAF HETG to detect resonance
absorption lines from the Damped Lyman-alpha (DLA) clouds.",9805110v1
1998-05-28,Photon Damping of Waves in Accretion Disks,"MHD turbulence is generally believed to have two important functions in
accretion disks: it transports angular momentum outward, and the energy in its
shortest wavelength modes is dissipated into the heat that the disks radiate.
In this paper we examine a pair of mechanisms which may play an important role
in regulating the amplitude and spectrum of this turbulence: photon diffusion
and viscosity. We demonstrate that in radiation pressure-dominated disks,
photon damping of compressive MHD waves is so rapid that it likely dominates
all other dissipation mechanisms.",9805358v1
1998-06-11,Damping of differential rotation in neutron stars,"We derive the transport relaxation times for quasiparticle-vortex scattering
processes via nuclear force, relevant for the damping of differential rotation
of superfluids in the quantum liquid core of a neutron star. The proton
scattering off the neutron vortices provides the dominant resistive force on
the vortex lattice at all relevant temperatures in the phase where neutrons
only are in the paired state. If protons are superconducting, a small fraction
of hyperons and resonances in the normal state would be the dominant source of
friction on neutron and proton vortex lattices at the core temperatures $T\ge
10^{7}$ K.",9806156v1
1999-03-10,Elemental abundances at early times: the nature of Damped Lyman-alpha systems,"The distribution of element abundances with redshift in Damped Ly-alpha (DLA)
systems can be adequately reproduced by the same model reproducing the halo and
disk components of the Milky Way Galaxy at different galactocentric distances:
DLA systems are well represented by normal spiral galaxies in their early
evolutionary stages.",9903150v1
1999-07-26,"Are Damped Ly-alpha Systems Large, Galactic Disks ?","The hypothesis that the Damped Ly-alpha systems (DLAs) are large, galactic
disks (Milky Way sized) is tested by confronting predictions of models of the
formation and evolution of (large) disk galaxies with observations, in
particular the Zinc abundance distribution with neutral hydrogen column density
found for DLAs. A pronounced mismatch is found strongly hinting that the
majority of DLAs may not be large, galactic disks.",9907349v1
1999-08-26,Oscillator Strengths and Damping Constants for Atomic Lines in the J and H Bands,"We have built a line list in the near-infrared J and H bands (1.00-1.34,
1.49-1.80 um) by gathering a series of laboratory and computed line lists.
Oscillator strengths and damping constants were computed or obtained by fitting
the solar spectrum.
  The line list presented in this paper is, to our knowledge, the most complete
one now available, and supersedes previous lists.",9908296v1
1999-11-25,Probing Solar Convection,"In the solar convection zone acoustic waves are scattered by turbulent sound
speed fluctuations. In this paper the scattering of waves by convective cells
is treated using Rytov's technique. Particular care is taken to include
diffraction effects which are important especially for high-degree modes that
are confined to the surface layers of the Sun. The scattering leads to damping
of the waves and causes a phase shift. Damping manifests itself in the width of
the spectral peak of p-mode eigenfrequencies. The contribution of scattering to
the line widths is estimated and the sensitivity of the results on the assumed
spectrum of the turbulence is studied. Finally the theoretical predictions are
compared with recently measured line widths of high-degree modes.",9911469v1
1999-12-14,The Gas Reservoir for present day Galaxies : Damped Ly-alpha Absorption Systems,"We present results from an ongoing search for galaxy counterparts of a
subgroup of Quasar Absorption Line Systems called Damped Ly-alpha Absorbers
(DLAs). DLAs have several characteristics that make them essential in the
process of understanding how galaxies formed in the early universe and evolved
to the galaxies we see today in the local universe.
  Finally we compare DLAs with recent findings of a population of starforming
galaxies at high redshifts, so called Lyman-break galaxies.",9912268v1
2000-06-22,Nuclear Reaction Rates in a Plasma: The Effect of Highly Damped Modes,"The fluctuation-dissipation theorem is used to evaluate the screening factor
of nuclear reactions due to the electromagnetic fluctuations in a plasma. We
show that the commonly used Saltpeter factor is obtained if only fluctuations
near the plasma eigenfrequency are assumed to be important (\omega \sim
\omega_{pe}\ll T (\hbar=k_{B}=1)). By taking into account all the fluctuations,
the highly damped ones, with \omega >\omega_{pe}, as well as those with
\omega\leq\omega_{pe}, we find that nuclear reaction rates are higher than
those obtained using the Saltpeter factor, for many interesting plasmas.",0006326v1
2000-09-06,The Cosmological Evolution of Quasar Damped Lyman-Alpha Systems,"We present results from an efficient, non-traditional survey to discover
damped Lyman-alpha (DLA) absorption-line systems with neutral hydrogen column
densities N(HI)>2x10^{20} atoms cm^{-2} and redshifts z<1.65. Contrary to
previous studies at higher redshift that showed a decrease in the cosmological
mass density of neutral gas in DLA absorbers, Omega_{DLA}, with time, our
results indicate that Omega_{DLA} is consistent with remaining constant from
redshifts z \approx 4 to z \approx 0.5. There is no evidence that Omega_{DLA}
is approaching the value at z=0. Other interesting results from the survey are
also presented.",0009098v1
2001-01-13,Measuring Feedback in Damped Lyman Alpha Systems,"We measure feedback (heating rates) in damped Lyman alpha systems from the
cooling rate of the neutral gas. Since cooling occurs through [C II] 158 micron
emission, we infer cooling from C II^{*} 1335.7 absorption lines detected with
HIRES on the Keck I telescope. The inferred heating rates are about 30 times
lower than for the Galaxy ISM. At z = 2.8, the implied star formation rate per
unit area is 10^{-2.4+-0.3} solar masses per kpc^{2} per year, and the the star
formation rate per unit comoving volume is 10^{-0.8+-0.2} solar masses per
Mpc^{3} per year. This is the first measurement of star formation rates in
objects likely to be the progenitors of current galaxies.",0101218v1
2001-04-18,The First Detection of Cobalt in a Damped Lyman Alpha System,"We present the first ever detection of Cobalt in a Damped Lyman Alpha system
(DLA) at z = 1.92. In addition to providing important clues to the star
formation history of these high redshift galaxies, we discuss how studying the
Co abundance in DLAs may also help to constrain models of stellar
nucleosynthesis in a regime not probed by Galactic stars.",0104301v1
2001-05-09,Nuclear reaction rates and energy in stellar plasmas : The effect of highly damped modes,"The effects of the highly damped modes in the energy and reaction rates in a
plasma are discussed. These modes, with wavenumbers $k \gg k_{D}$, even being
only weakly excited, with less than $k_{B}T$ per mode, make a significant
contribution to the energy and screening in a plasma. When the de Broglie
wavelength is much less than the distance of closest approach of thermal
electrons, a classical analysis of the plasma can",0105153v1
2001-07-03,The HI Content and Extent of Low Surface Brightness Galaxies - Could LSB Galaxies be Responsible for Damped Ly-alpha Absorption?,"Low surface brightness galaxies, those galaxies with a central surface
brightness at least one magnitude fainter than the night sky, are often not
included in discussions of extragalactic gas at z < 0.1. In this paper we
review many of the properties of low surface brightness galaxies, including
recent studies which indicate low surface brightness systems may contribute far
more to the local HI luminosity function than previously thought. Additionally,
we use the known (HI) gas properties of low surface brightness galaxies to
consider their possible contribution to nearby damped Lyman-alpha absorbers.",0107064v1
2001-09-10,H_2 molecules in damped systems,"Damped Lyman alpha systems seen in the spectra of high-z QSOs arise in
high-density neutral gas in which molecular hydrogen (H_2) should be
conspicuous. Systematic searches to detect the H_2 lines redshifted into the
Lyman alpha forest at <3400\AA are now possible thanks to the unique
capabilities of UVES on the VLT. Here we summarise the present status of our on
going programme to search for H_2 in DLAs, discuss the physical conditions in
the systems where H_2 is detected and the implications of non-detections.",0109155v1
2001-10-23,A scaling law of interstellar depletions as a tool for abundance studies of Damped Ly alpha systems,"An analytical expression is presented that allows dust depletions to be
estimated in different types of interstellar environments, including Damped Ly
alpha systems. The expression is a scaling law of a reference depletion pattern
and takes into account the possibility that the dust chemical composition may
vary as a function of the dust-to-metals ratio and of the intrinsic abundances
of the medium. Preliminary tests and applications of the proposed scaling law
are briefly reported.",0110499v1
2002-09-23,Outflows in Galaxies and Damped Ly-alpha System,"Although quasar absorbers, and in particular Damped Lyman-alpha systems
(DLAs) have proven a valuable tool to study the early Universe, their exact
nature is so far poorly constrained. It has been suggested that outflows in
galaxies might account for at least part of the DLA population. Observational
evidences and models in support of this hypothesis are reviewed, including
recent observations of Lyman Break Galaxies (LBGs). Observational
counter-arguments and theoretical limitations are also given. Finally,
implications of such a model for the environment of galaxies at high-redshifts
are discussed.",0209463v1
2004-03-15,The Damping Wing of the Gunn-Peterson Absorption and Lyman-Alpha Emitters in the Pre-Reionization Era,"We use a numerical simulation of cosmological reionization to estimate the
likelihood of detecting Lyman-alpha emitting galaxies during the
pre-reionization era. We show that it is possible to find galaxies even at z~9
that are barely affected by the dumping wing of the Gunn-Peterson absorption
from the neutral IGM outside of their HII regions. The damping wing becomes
rapidly more significant at z>9, but even at z>10 is it not inconceivable
(although quite hard) to see a Lyman-alpha emission line from a star-forming
galaxy.",0403345v1
2005-05-28,Cosmic ray transport in MHD turbulence,"Recent advances in understanding of magnetohydrodynamic (MHD) turbulence call
for revisions in the picture of cosmic ray transport. In this paper we use
recently obtained scaling laws for MHD modes to obtain the scattering frequency
for cosmic rays. We account for the turbulence cutoff arising from both
collisional and collisionless damping. We obtain the scattering rate and show
that fast modes provide the dominant contribution to cosmic ray scattering for
the typical interstellar conditions in spite of the fact that fast modes are
subjected to damping. We determine how the efficiency of the scattering depends
on the characteristics of ionized media, e.g. plasma $\beta$. We show that
streaming instability is suppressed by the ambient MHD turbulence.",0505575v1
2005-06-09,Phantom damping of matter perturbations,"Cosmological scaling solutions are particularly important in solving the
coincidence problem of dark energy. We derive the equations of sub-Hubble
linear matter perturbations for a general scalar-field Lagrangian--including
quintessence, tachyon, dilatonic ghost condensate and k-essence--and solve them
analytically for scaling solutions. We find that matter perturbations are
always damped if a phantom field is coupled to dark matter and identify the
cases in which the gravitational potential is constant. This provides an
interesting possibility to place stringent observational constraints on scaling
dark energy models.",0506222v1
2005-06-22,A Damped Ly-alpha Absorption-line System in an Apparent Void at Redshift 2.38,"We study the contents of an apparent void in the distribution of Ly-alpha
emitting galaxies at redshift 2.38. We show that this void is not empty, but
contains a damped Ly-alpha absorption-line system, seen in absorption against
background QSO 2138-4427. Imaging does not reveal any galaxy associated with
this absorption-line system, but it contains metals (Fe/H ~ -1.3), and its
large velocity range (~ 180 km/s) implies a significant mass.",0506525v1
2005-08-08,Fluorescence in damp air and comments on the radiative life time,"Photon yields in damp air excited by an electron using a Sr90 $\beta$ source
are compared withthose in dry air. Water vapors considerably reduce the yields,
however, a further study is needed to evaluate the effects on the energy
estimation of ultrahigh-energy cosmic rays. The relation of fluorescence
efficiency to the life time of de-excitation by radiation is discussed.",0508183v1
2006-08-17,Electron thermal conductivity owing to collisions between degenerate electrons,"We calculate the thermal conductivity of electrons produced by
electron-electron Coulomb scattering in a strongly degenerate electron gas
taking into account the Landau damping of transverse plasmons. The Landau
damping strongly reduces this conductivity in the domain of ultrarelativistic
electrons at temperatures below the electron plasma temperature. In the inner
crust of a neutron star at temperatures T < 1e7 K this thermal conductivity
completely dominates over the electron conductivity due to electron-ion
(electron-phonon) scattering and becomes competitive with the the electron
conductivity due to scattering of electrons by impurity ions.",0608371v1
2006-09-19,"Dust, Metals and Diffuse Interstellar Bands in Damped Lyman Alpha Systems","Although damped Lyman alpha (DLA) systems are usually considered metal-poor,
it has been suggested that this could be due to observational bias against
metal-enriched absorbers. I review recent surveys to quantify the particular
issue of dust obscuration bias and demonstrate that there is currently no
compelling observational evidence to support a widespread effect due to
extinction. On the other hand, a small sub-set of DLAs may be metal-rich and I
review some recent observations of these metal-rich absorbers and the detection
of diffuse interstellar bands in one DLA at z ~ 0.5.",0609530v1
2006-11-08,Comments on Viscous Damping of Non-Adiabatic MHD Waves in an Unbounded Solar Coronal Plasma by Kumar and Kumar,"Considering thermal conduction, compressive viscosity and optically thin
radiation as damping mechanisms for MHD waves, we derive a six-order general
dispersion relation. We point out a fundamental flaw in the derivation of
five-order dispersion relation by Kumar and Kumar (2006) who adopt as a basis
vector. The correct definition of the motion in the x-z plane (2-D vector
space) stems from the two independent variables, namely .",0611252v2
2007-01-10,Non-gaussianity in fluctuations from warm inflation,"The scalar mode density perturbations in a the warm inflationary scenario are
analysed with a view to predicting the amount of non-gaussianity produced by
this scenario. The analysis assumes that the inflaton evolution is strongly
damped by the radiation, with damping terms that are temperature independent.
Entropy fluctuations during warm inflation play a crucial role in generating
non-gaussianity and result in a distinctive signal which should be observable
by the Planck satellite.",0701302v2
1998-05-22,WKB for a damped spin,"The master equation for a damped spin well known from the theory of
superradiance, is written as a finite-difference equation and solved by a
WKB-like method. The propagator thus obtained looks like the van Vleck
propagator of a certain classical Hamiltonian system with one degree of
freedom. A new interpretation is provided of the temporal broadening of
initially sharp probability distributions as the analogue of the spreading of
the quantum mechanical wave packet.",9805018v1
1998-11-04,Cascades of energy and helicity in the GOY shell model of turbulence,"The effect of extreme hyperviscous damping, $\nu k_n^p, p=\infty$ is studied
numerically in the GOY shell model of turbulence. It has resently been
demonstrated [Leveque and She, Phys. Rev. Lett, 75,2690 (1995)] that the
inertial range scaling in the GOY model is non-universal and depending on the
viscous damping. The present study shows that the deviation from Kolmogorov
scaling is due to the cascade of the second inviscid invariant. This invariant
is non-positive definite and in this sense analogous to the helicity of 3D
turbulent flow.",9811009v1
1994-02-04,Effects of Disorder in a Dilute Bose Gas,"We discuss the effects of a weak random external potential on the properties
of the dilute Bose gas at zero temperature. The results recently obtained by
Huang and Meng for the depletion of the condensate and of the superfluid
density are recovered. Results for the shift of the velocity of sound as well
as for its damping due to collisions with the external field are presented. The
damping of phonons is calculated also for dense superfluids. (submitted to
Phys.Rev.B)",9402015v1
1995-02-10,The influence of structure disorder on mean atomic momentum fluctuations and a spin-wave spectrum,"The relation between atomic momenta fluctuations and density fluctuations is
obtained in frames of mean-field approximation. Using two-time temperature
Green functions within Tyablikov approximation the equations for spin
excitation energy and damping are obtained. The asymptotics of energy and
damping in the long-wave limit are investigated and the anomalous behaviour of
spin-wave stiffness constant is discussed.",9502042v1
1997-02-13,"Comment on ""Collective Excitations of a Bose-Einstein Condensate in a Magnetic Trap""","We calculate the damping rate of collective excitations for a nearly pure
Bose-Einstein condensate regarding the recent experiments in MIT [M.-O. Mews et
al, Phys. Rev. Lett. 77, 988 (1996)]. The decay time of collective excitations
obtained in our theoretical calculations agrees well with their experimental
result. We argue that the damping of collective excitations is due to thermal
contributions rather than interactions between collective modes.",9702122v1
1997-08-14,Landau damping in dilute Bose gases,"Landau damping in weakly interacting Bose gases is investigated by means of
perturbation theory. Our approach points out the crucial role played by
Bose-Einstein condensation and yields an explicit expression for the decay rate
of elementary excitations in both uniform and non uniform gases. Systematic
results are derived for the phonon width in homogeneous gases interacting with
repulsive forces. Special attention is given to the low and high temperature
regimes.",9708104v1
1997-11-07,Coulomb suppression of NMR coherence peak in fullerene superconductors,"The suppressed NMR coherence peak in the fullerene superconductors is
explained in terms of the dampings in the superconducting state induced by the
Coulomb interaction between conduction electrons. The Coulomb interaction,
modelled in terms of the onsite Hubbard repulsion, is incorporated into the
Eliashberg theory of superconductivity with its frequency dependence considered
self-consistently at all temperatures. The vertex correction is also included
via the method of Nambu. The frequency dependent Coulomb interaction induces
the substantial dampings in the superconducting state and, consequently,
suppresses the anticipated NMR coherence peak of fullerene superconductors as
found experimentally.",9711060v2
1997-12-09,The Sound of Sonoluminescence,"We consider an air bubble in water under conditions of single bubble
sonoluminescence (SBSL) and evaluate the emitted sound field nonperturbatively
for subsonic gas-liquid interface motion. Sound emission being the dominant
damping mechanism, we also implement the nonperturbative sound damping in the
Rayleigh-Plesset equation for the interface motion. We evaluate numerically the
sound pulse emitted during bubble collapse and compare the nonperturbative and
perturbative results, showing that the usual perturbative description leads to
an overestimate of the maximal surface velocity and maximal sound pressure. The
radius vs. time relation for a full SBSL cycle remains deceptively unaffected.",9712097v1
1998-07-02,Linear systems with adiabatic fluctuations,"We consider a dynamical system subjected to weak but adiabatically slow
fluctuations of external origin. Based on the ``adiabatic following''
approximation we carry out an expansion in \alpha/|\mu|, where \alpha is the
strength of fluctuations and 1/|\mu| refers to the time scale of evolution of
the unperturbed system to obtain a linear differential equation for the average
solution. The theory is applied to the problems of a damped harmonic oscillator
and diffusion in a turbulent fluid. The result is the realization of
`renormalized' diffusion constant or damping constant for the respective
problems. The applicability of the method has been critically analyzed.",9807031v1
1998-12-02,Vortex lattice melting and the damping of the dHvA oscillations in the mixed state,"Phase fluctuations in the superconducting order parameter, which are
responsible for the melting of the Abrikosov vortex lattice below the mean
field $H_{c2}$, are shown to dramatically enhance the scattering of
quasi-particles by the fluctuating pair potential, thus leading to enhanced
damping of the dHvA oscillations in the liquid mixed state. This effect is
shown to quantitatively account for the detailed field dependence of the dHvA
amplitude observed recently in the mixed state of a Quasi 2D organic SC.",9812040v1
1999-01-19,Damping of Growth Oscillations,"Computer simulations and scaling theory are used to investigate the damping
of oscillations during epitaxial growth on high-symmetry surfaces. The
crossover from smooth to rough growth takes place after the deposition of
(D/F)^\delta monolayers, where D and F are the surface diffusion constant and
the deposition rate, respectively, and the exponent \delta=2/3 on a
two-dimensional surface. At the transition, layer-by-layer growth becomes
desynchronized on distances larger than a layer coherence length proportional
l^2, where l is a typical distance between two-dimensional islands in the
submonolayer region of growth.",9901178v1
1999-06-15,Temperature-induced resonances and Landau damping of collective modes in Bose-Einstein condensed gases in spherical traps,"Interaction between collective monopole oscillations of a trapped
Bose-Einstein condensate and thermal excitations is investigated by means of
perturbation theory. We assume spherical symmetry to calculate the matrix
elements by solving the linearized Gross-Pitaevskii equations. We use them to
study the resonances of the condensate induced by temperature when an external
perturbation of the trapping frequency is applied and to calculate the Landau
damping of the oscillations.",9906214v1
1999-08-03,Kinetic Theory of Collective Modes in Atomic Clouds above the Bose-Einstein Transition Temperature,"We calculate frequencies and damping rates of the lowest collective modes of
a dilute Bose gas confined in an anisotropic trapping potential above the
Bose-Einstein transition temperature. From the Boltzmann equation with a
simplified collision integral we derive a general dispersion relation that
interpolates between the collisionless and hydrodynamic regimes. In the case of
axially symmetric traps we obtain explicit expressions for the frequencies and
damping rates of the lowest modes in terms of a phenomenological collision
time. Our results are compared with microscopic calculations and experiments.",9908043v1
1999-09-01,Normal Fermi Liquid Behavior of Quasiholes in the Spin-Polaron Model for Copper Oxides,"Based on the t-J model and the self-consistent Born approximation, the
damping of quasiparticle hole states near the Fermi surface is calculated in a
low doping regime. Renormalization of spin-wave excitations due to hole doping
is taken into account. The damping is shown to be described by a familiar form
$\text{Im}\Sigma({\bf k}^{\prime},\epsilon)\propto (\epsilon^{2}/
\epsilon_{F})\ln(\epsilon/ \epsilon_{F})$ characteristic of the 2-dimensional
Fermi liquid, in contrast with the earlier statement reported by Li and Gong
[Phys. Rev. B {\bf 51}, 6343 (1995)] on the marginal Fermi liquid behavior of
quasiholes.",9909020v1
1999-12-01,Impurity relaxation mechanism for dynamic magnetization reversal in a single domain grain,"The interaction of coherent magnetization rotation with a system of two-level
impurities is studied. Two different, but not contradictory mechanisms, the
`slow-relaxing ion' and the `fast-relaxing ion' are utilized to derive a system
of integro-differential equations for the magnetization. In the case that the
impurity relaxation rate is much greater than the magnetization precession
frequency, these equations can be written in the form of the Landau-Lifshitz
equation with damping. Thus the damping parameter can be directly calculated
from these microscopic impurity relaxation processes.",9912014v1
2000-02-16,Dissipative dynamics of Bose condensates in optical cavities,"We study the zero temperature dynamics of Bose-Einstein condensates in driven
high-quality optical cavities in the limit of large atom-field detuning. We
calculate the stationary ground state and the spectrum of coupled atom and
field mode excitations for standing wave cavities as well as for travelling
wave cavities. Finite cavity response times lead to damping or controlled
amplification of these excitations. Analytic solutions in the Lamb-Dicke
expansion are in good agreement with numerical results for the full problem and
show that oscillation frequencies and the corresponding damping rates are
qualitatively different for the two cases.",0002247v1
2000-03-27,Effect of memory and dynamical chaos in long Josephson junctions,"A long Josephson junction in a constant external magnetic field and in the
presence of a dc bias current is investigated. It is shown that the system,
simulated by the sine-Gorgon equation, ""remembers"" a rapidly damping initial
perturbation and final asymptotic states are determined exactly with this
perturbation. Numerical solving of the boundary sine-Gordon problem and
calculations of Lyapunov indices show that this system has a memory even when
it is in a state of dynamical chaos, i.e., dynamical chaos does not destroy
initial information having a character of rapidly damping perturbation.",0003421v1
2000-09-13,Oscillations of the superconducting order parameter in a ferromagnet,"Planar tunneling spectroscopy reveals damped oscillations of the
superconducting order parameter induced into a ferromagnetic thin film by the
proximity effect. The oscillations are due to the finite momentum transfer
provided to Cooper pairs by the splitting of the spin up and down bands in the
ferromagnet. As a consequence, for negative values of the superconducting order
parameter the tunneling spectra are capsized (""$\pi$-state""). The oscillations'
damping and period are set by the same length scale, which depends on the spin
polarization.",0009192v1
2000-09-29,Damping and revivals of collective oscillations in a finite-temperature model of trapped Bose-Einstein condensation,"We utilize a two-gas model to simulate collective oscillations of a
Bose-Einstein condensate at finite temperatures. The condensate is described
using a generalized Gross-Pitaevskii equation, which is coupled to a thermal
cloud modelled by a Monte Carlo algorithm. This allows us to include the
collective dynamics of both the condensed and non-condensed components
self-consistently. We simulate quadrupolar excitations, and measure the damping
rate and frequency as a function of temperature. We also observe revivals in
condensate oscillations at high temperatures, and in the thermal cloud at low
temperature. Extensions of the model to include non-equilibrium effects and
describe more complex phenomena are discussed.",0009468v1
2001-04-18,Effective rate equations for the over-damped motion in fluctuating potentials,"We discuss physical and mathematical aspects of the over-damped motion of a
Brownian particle in fluctuating potentials. It is shown that such a system can
be described quantitatively by fluctuating rates if the potential fluctuations
are slow compared to relaxation within the minima of the potential, and if the
position of the minima does not fluctuate. Effective rates can be calculated;
they describe the long-time dynamics of the system. Furthermore, we show the
existence of a stationary solution of the Fokker-Planck equation that describes
the motion within the fluctuating potential under some general conditions. We
also show that a stationary solution of the rate equations with fluctuating
rates exists.",0104330v1
2001-09-05,Spin Excitations in a Fermi Gas of Atoms,"We have experimentally investigated a spin excitation in a quantum degenerate
Fermi gas of atoms. In the hydrodynamic regime the damping time of the
collective excitation is used to probe the quantum behavior of the gas. At
temperatures below the Fermi temperature we measure up to a factor of 2
reduction in the excitation damping time. In addition we observe a strong
excitation energy dependence for this quantum statistical effect.",0109098v2
2001-10-09,Freezing of a Stripe Liquid,"The existence of a stripe-liquid phase in a layered nickelate,
La(1.725)Sr(0.275)NiO(4), is demonstrated through neutron scattering
measurements. We show that incommensurate magnetic fluctuations evolve
continuously through the charge-ordering temperature, although an abrupt
decrease in the effective damping energy is observed on cooling through the
transition. The energy and momentum dependence of the magnetic scattering are
parametrized with a damped-harmonic-oscillator model describing overdamped
spin-waves in the antiferromagnetic domains defined instantaneously by charge
stripes.",0110191v2
2001-12-13,Magnon softening and damping in the ferromagnetic manganites due to orbital correlations,"We present a theory for spin excitations in ferromagnetic metallic manganites
and demonstrate that orbital fluctuations have strong effects on the magnon
dynamics in the case these compounds are close to a transition to an orbital
ordered state. In particular we show that the scattering of the spin
excitations by low-lying orbital modes with cubic symmetry causes both the
magnon softening and damping observed experimentally.",0112252v2
2002-01-16,Quantum Spin dynamics of the Bilayer Ferromagnet La(1.2)Sr(1.8)Mn2O7,"We construct a theory of spin wave excitations in the bilayer manganite
La(1.2)Sr(1.8)Mn2O7 based on the simplest possible double-exchange model, but
including leading quantum corrections to the spin wave dispersion and damping.
Comparison is made with recent inelastic neutron scattering experiments. We
find that quantum effects account for some part of the measured damping of spin
waves, but cannot by themselves explain the observed softening of spin waves at
the zone boundary. Furthermore a doping dependence of the total spin wave
dispersion and the optical spin wave gap is predicted.",0201269v1
2002-02-21,Dynamics of a Bose-Einstein condensate at finite temperature in an atomoptical coherence filter,"The macroscopic coherent tunneling through the barriers of a periodic
potential is used as an atomoptical filter to separate the condensate and the
thermal components of a $^{87}$Rb mixed cloud. We condense in the combined
potential of a laser standing-wave superimposed on the axis of a cigar-shape
magnetic trap and induce condensate dipole oscillation in the presence of a
static thermal component. The oscillation is damped due to interaction with the
thermal fraction and we investigate the role played by the periodic potential
in the damping process.",0202369v1
2002-03-11,A Damping of the de Haas-van Alphen Oscillations in the superconducting state,"Deploying a recently developed semiclassical theory of quasiparticles in the
superconducting state we study the de Haas-van Alphen effect. We find that the
oscillations have the same frequency as in the normal state but their amplitude
is reduced. We find an analytic formulae for this damping which is due to
tunnelling between semiclassical quasiparticle orbits comprising both
particle-like and hole-like segments. The quantitative predictions of the
theory are consistent with the available data.",0203224v1
2002-03-26,Measurement induced quantum-classical transition,"A model of an electrical point contact coupled to a mechanical system
(oscillator) is studied to simulate the dephasing effect of measurement on a
quantum system. The problem is solved at zero temperature under conditions of
strong non-equilibrium in the measurement apparatus. For linear coupling
between the oscillator and tunneling electrons, it is found that the oscillator
dynamics becomes damped, with the effective temperature determined by the
voltage drop across the junction. It is demonstrated that both the quantum
heating and the quantum damping of the oscillator manifest themselves in the
current-voltage characteristic of the point contact.",0203521v3
2002-07-04,Fluctuations and correlations in hexagonal optical patterns,"We analyze the influence of noise in transverse hexagonal patterns in
nonlinear Kerr cavities. The near field fluctuations are determined by the
neutrally stable Goldstone modes associated to translational invariance and by
the weakly damped soft modes. However these modes do not contribute to the far
field intensity fluctuations which are dominated by damped perturbations with
the same wave vectors than the pattern. We find strong correlations between the
intensity fluctuations of any arbitrary pair of wave vectors of the pattern.
Correlation between pairs forming 120 degrees is larger than between pairs
forming 180 degrees, contrary to what a naive interpretation of emission in
terms of twin photons would suggest.",0207127v2
2002-09-19,Damping of long-wavelength collective excitations in quasi-onedimensional Fermi liquids,"The imaginary part of the exchange-correlation kernel in the longitudinal
current-current response function of a quasi-onedimensional Fermi liquid is
evaluated by an approximate decoupling in the equation of motion for the
current density, which accounts for processes of excitation of two
particle-hole pairs. The two-pair spectrum determines the intrinsic damping
rate of long-wavelength collective density fluctuations, which is calculated
and contrasted with a result previously obtained for a clean Luttinger liquid.",0209455v1
2002-11-01,Exploring dynamical magnetism with time-dependent density-functional theory: from spin fluctuations to Gilbert damping,"We use time-dependent spin-density-functional theory to study dynamical
magnetic phenomena. First, we recall that the local-spin-density approximation
(LSDA) fails to account correctly for magnetic fluctuations in the paramagnetic
state of iron and other itinerant ferromagnets. Next, we construct a
gradient-dependent density functional that does not suffer from this problem of
the LSDA. This functional is then used to derive, for the first time, the
phenomenological Gilbert equation of micromagnetics directly from
time-dependent density-functional theory. Limitations and extensions of Gilbert
damping are discussed on this basis, and some comparisons with phenomenological
theories and experiments are made.",0211021v1
2002-11-05,Magnetic fluctuations and resonant peak in cuprates: a microscopic theory,"The theory for the dynamical spin susceptibility within the t-J model is
developed, as relevant for the resonant magnetic peak and normal-state magnetic
response in superconducting (SC) cuprates. The analysis is based on the
equations of motion for spins and the memory-function presentation of magnetic
response where the main damping of the low-energy spin collective mode comes
from the decay into fermionic degrees of freedom. It is shown that the damping
function at low doping is closely related to the c-axis optical conductivity.
The analysis reproduces doping-dependent features of the resonant magnetic
scattering.",0211090v1
2002-11-20,Damping of Nodal Fermions Caused by a Dissipative Mode,"Using a $d_{x^2 - y^2}$ superconductor in 2+1 dimensions we show that the
Nambu Goldstone fluctuations are replaced by dissipative excitations. We find
that the nodal quasi-particles damping is caused by the strong dissipative
excitations near the nodal points. As a result we find that the scattering
rates are linear in frequency and not cubic as predicted in the literature for
the ``d'' wave superconductors. Our results explain the recent angle resolved
photoemission spectroscopy and optical conductivity in the BSCCO high $T_c$
compounds.",0211440v1
2002-11-22,Nonlinear microscopic relaxation of uniform magnetization precession,"Dynamic relaxation for nonlinear magnetization excitation is analyzed. For
direct processes, such as magnon-electron scattering and two-magnon scattering,
the relaxation rate is determined from the linear case simply by utilizing the
magnetization oscillation frequency for nonlinear excitation. For an indirect
process, such as slow-relaxing impurities, the analysis gives an additional
relaxation term proportional to the excitation level. In all cases the
effective magnetization damping is increased compared to
Landau-Lifshitz-Gilbert damping.",0211499v1
2003-04-04,Dynamic exchange coupling and Gilbert damping in magnetic multilayers,"We theoretically study dynamic properties of thin ferromagnetic films in
contact with normal metals. Moving magnetizations cause a flow of spins into
adjacent conductors, which relax by spin flip, scatter back into the
ferromagnet, or are absorbed by another ferromagnet. Relaxation of spins
outside the moving magnetization enhances the overall damping of the
magnetization dynamics in accordance with the Gilbert phenomenology. Transfer
of spins between different ferromagnets by these nonequilibrium spin currents
leads to a long-ranged dynamic exchange interaction and novel collective
excitation modes. Our predictions agree well with recent
ferromagnetic-resonance experiments on ultrathin magnetic films.",0304116v1
2003-05-27,Dynamics of a classical gas including dissipative and mean field effects,"By means of a scaling ansatz, we investigate an approximated solution of the
Boltzmann-Vlasov equation for a classical gas. Within this framework, we derive
the frequencies and the damping of the collective oscillations of a
harmonically trapped gas and we investigate its expansion after release of the
trap. The method is well suited to studying the collisional effects taking
place in the system and in particular to discussing the crossover between the
hydrodynamic and the collisionless regimes. An explicit link between the
relaxation times relevant for the damping of the collective oscillations and
for the expansion is established.",0305624v1
2003-07-21,Chaotic scattering of a quantum particle weakly coupled to a very complicated background,"Effect of a complicated many-body environment is analyzed on the chaotic
motion of a quantum particle in a mesoscopic ballistic structure. The dephasing
and absorption phenomena are treated on the same footing in the framework of a
model which is free of the ambiguities inherent to earlier models. The
single-particle doorway resonance states excited via an external channel are
damped not only because of the escape onto such channels but also due to
ulterior population of long-lived background states, the resulting internal
damping being uniquely characterized by the spreading width. On the other hand,
the formation of the fine-structure resonances strongly enhances the delay time
fluctuations thus broadening the delay time distribution.",0307496v1
2003-09-24,Landau Damping in a 2D Electron Gas with Imposed Quantum Grid,"Dielectric properties of semiconductor substrate with imposed two dimensional
(2D) periodic grid of quantum wires or nanotubes (quantum crossbars, QCB) are
studied. It is shown that a capacitive contact between QCB and semiconductor
substrate does not destroy the Luttinger liquid character of the long wave QCB
excitations. However, the dielectric losses of a substrate surface are
drastically modified due to diffraction processes on the QCB superlattice.
QCB-substrate interaction results in additional Landau damping regions of the
substrate plasmons. Their existence, form and the density of losses are
strongly sensitive to the QCB lattice constant.",0309546v2
2003-11-21,Self-stabilised fractality of sea-coasts through damped erosion,"Erosion of rocky coasts spontaneously creates irregular seashores. But the
geometrical irregularity, in turn, damps the sea-waves, decreasing the average
wave amplitude. There may then exist a mutual self-stabilisation of the waves
amplitude together with the irregular morphology of the coast. A simple model
of such stabilisation is studied. It leads, through a complex dynamics of the
earth-sea interface, to the appearance of a stationary fractal seacoast with
dimension close to 4/3. Fractal geometry plays here the role of a morphological
attractor directly related to percolation geometry.",0311509v1
2003-12-10,Exciton-LO-phonon dynamics in InAs/GaAs quantum dots: Effects of zone-edge phonon damping,"The dynamics of an exciton-LO-phonon system after an ultrafast optical
excitation in an InAs/GaAs quantum dot is studied theoretically. Influence of
anharmonic phonon damping and its interplay with the phonon dispersion is
analyzed. The signatures of the zone-edge decay process in the absorption
spectrum and time evolution are highlighted, providing a possible way of
experimental investigation on phonon anharmonicity effects.",0312256v2
2004-01-13,Vortex waves and the onset of turbulence in $^3$He-B,"In a recent experiment Finne et al. discovered an intrinsic condition for the
onset of quantum turbulence in $^3$He-B, that q=alpha/(1-alpha')<1, where alpha
and alpha' are mutual friction parameters. The authors argued that this
condition corresponds to Kelvin waves which are marginally damped, so for q>1
Kelvin waves cannot grow in amplitude and trigger vortex reconnections and
turbulence. By analysing both axisymmetric and non-axisymmetric modes of
oscillations of a rotating superfluid, we confirm that in the long axial
wavelength limit the simple condition q=1 is indeed the crossover between
damped and propagating Kelvin waves.",0401212v1
2004-01-28,Long lived acoustic vibrational modes of an embedded nanoparticle,"Classical continuum elastic calculations show that the acoustic vibrational
modes of an embedded nanoparticle can be lightly damped even when the
longitudinal plane wave acoustic impedances $Z_o=\rho v_L$ of the nanoparticle
and the matrix are the same. It is not necessary for the matrix to be less
dense or softer than the nanoparticle in order to have long lived vibrational
modes. Continuum boundary conditions do not always accurately reflect the
microscropic nature of the interface between nanoparticle and matrix, and a
multi-layer model of the interface reveals the possibility of additional
reduction of mode damping.",0401579v2
2004-07-20,Dynamics of a trapped ultracold two-dimensional atomic gas,"This article is devoted to the study of two-dimensional Bose gases
harmonically confined. We first summarize their equilibrium properties. For
such a gas above the critical temperature, we also derive the frequencies and
the damping of the collective oscillations and we investigate its expansion
after releasing of the trap. The method is well suited to study the collisional
effects taking place in the system and in particular to discuss the crossover
between the hydrodynamic and the collisionless regimes. We establish the link
between the relaxation times relevant for the damping of the collective
oscillations and for the time-of-flight expansion. We also evaluate the
collision rate and its relationship with the relaxation time.",0407522v1
2004-12-06,Thermal wave packets induced by attosecond laser pulses,"In this paper the dynamics of the interaction of attosecond laser pulses with
matter is investigated. It will be shown that the master equation: modified
Klein-Gordon equation describes the propagation of the heatons. Heatons are the
thermal wave packets. When the duration of the laser pulsees \delta t is of the
order of attosecond the heaton-thermal wave packets are nondispersive objects.
For \delta t \to \infty, the heatons are damped with damping factor of the
order of relaxation time for thermal processes.
  Key words: Temperature fields; Attosecond laser pulses; Heatons; Modified
Klein-Gordon equation.",0412126v1
2005-04-12,Nonlinear response and discrete breather excitation in driven micro-mechanical cantilever arrays,"We explain the origin of the generation of discrete breathers (DBs) in
experiments on damped and driven micromechanical cantilever arrays (M.Sato et
al. Phys. Rev. Lett. {\bf 90}, 044102, 2003). Using the concept of the
nonlinear response manifold (NLRM) we provide a systematic way to find the
optimal parameter regime in damped and driven lattices where DBs exist. Our
results show that DBs appear via a new instability of the NLRM different from
the anticipated modulational instability (MI) known for conservative systems.
We present several ways of exciting DBs, and compare also to experimental
studies of exciting and destroying DBs in antiferromagnetic layered systems.",0504298v1
2005-05-14,Monopole Oscillations and Dampings in Boson and Fermion Mixture in the Time-Dependent Gross-Pitaevskii and Vlasov Equations,"We construct a dynamical model for the time evolution of the boson-fermion
coexistence system. The dynamics of bosons and fermions are formulated with the
time-dependent Gross-Pitaevsky equation and the Vlasov equation. We thus study
the monopole oscillation in the bose-fermi mixture. We find that large damping
exists for fermion oscillations in the mixed system even at zero temperature.",0505357v1
2005-10-11,Non-damping magnetization oscillations in a single-domain ferromagnet,"Non-damped oscillations of the magnetization vector of a ferromagnetic system
subject to a spin polarized current and an external magnetic field are studied
theoretically by solving the Landau-Lifshitz-Gilbert equation. It is shown that
the frequency and amplitude of such oscillations can be controlled by means of
an applied magnetic field and a spin current. The possibility of injection of
the oscillating spin current into a non-magnetic system is also discussed.",0510280v1
2005-10-13,Superconducting Flywheel Model for Energy Storage Applications,"In order to explore the complexity and diversity of the flywheels' dynamics,
we have developed the real-physics computer model of a universal mechanical
rotor. Due to an arbitrary external force concept, the model can be adjusted to
operate identical to the real experimental prototype. Taking the high-speed
magnetic rotor on superconducting bearings as the prototype, the law for the
energy loss in real high temperature superconducting bearings has been derived.
Varying the laws of damping and elasticity in the system, we have found a way
to effectively damp the parasitic resonances and minimize the loss of energy
storage.",0510346v1
2005-11-05,Ratchet Effect in Magnetization Reversal of Stoner Particles,"A new strategy is proposed aimed at substantially reducing the minimal
magnetization switching field for a Stoner particle. Unlike the normal method
of applying a static magnetic field which must be larger than the magnetic
anisotropy, a much weaker field, proportional to the damping constant in the
weak damping regime, can be used to switch the magnetization from one state to
another if the field is along the motion of the magnetization. The concept is
to constantly supply energy to the particle from the time-dependent magnetic
field to allow the particle to climb over the potential barrier between the
initial and the target states.",0511135v1
2005-12-03,Apparent vibrational side-bands in pi-conjugated systems: the case of distyrylbenzene,"The photoluminescence (PL) spectra of dilute solution and single crystals of
distyrylbenzene show unique temperature dependent vibronic structures. The
characteristic single frequency progression at high temperatures is modulated
by a low frequency progression series at low temperatures. None of the series
side band modes corresponds to any of the distyrylbenzene Raman frequencies. We
explain these PL properties using a time dependent model with temperature
dependent damping, in which the many-mode system is effectively transformed to
two- and then to a single ""apparent"" mode as damping increases.",0512067v1
2006-05-26,Thermo-Plasma Polariton within Scaling Theory of Single-Layer Graphene,"Electrodynamics of single-layer graphene is studied in the scaling regime. At
any finite temperature, there is a weakly damped collective thermo-plasma
polariton mode whose dispersion and wavelength dependent damping is determined
analytically. The electric and magnetic fields associated with this mode decay
exponentially in the direction perpendicular to the graphene layer, but unlike
the surface plasma polariton modes of metals, the decay length and the mode
frequency are strongly temperature dependent. This may lead to new ways of
generation and manipulation of these modes.",0605642v1
2006-12-18,Shear viscosity and damping for a Fermi gas in the unitarity limit,"The shear viscosity of a two-component Fermi gas in the normal phase is
calculated as a function of temperature in the unitarity limit, taking into
account strong-coupling effects that give rise to a pseudogap in the spectral
density for single-particle excitations. The results indicate that recent
measurements of the damping of collective modes in trapped atomic clouds can be
understood in terms of hydrodynamics, with a decay rate given by the viscosity
integrated over an effective volume of the cloud.",0612460v2
2007-02-07,Damping of antiferromagnetic spin waves by valence fluctuations in the double layer perovskite YBaFe2O5,"Inelastic neutron scattering experiments show that spin dynamics in the
charge ordered insulating ground state of the double-layer perovskite YBaFe2O5
is well described in terms of eg superexchange interactions. Above the Verwey
transition at TV = 308 K, t2g double exchange-type conduction within
antiferromagnetic FeO2--BaO--FeO2 double layers proceeds by an electron hopping
process that requires a spin flip of the five-fold coordinated Fe ions, costing
an energy 5<J>S^2 of approximately 0.1 eV. The hopping process disrupts
near-neighbor spin correlations, leading to massive damping of zone-boundary
spin waves.",0702181v1
2007-02-20,Spin Drag and Spin-Charge Separation in Cold Fermi Gases,"Low-energy spin and charge excitations of one-dimensional interacting
fermions are completely decoupled and propagate with different velocities.
These modes however can decay due to several possible mechanisms. In this paper
we expose a new facet of spin-charge separation: not only the speeds but also
the damping rates of spin and charge excitations are different. While the
propagation of long-wavelength charge excitations is essentially ballistic,
spin propagation is intrinsically damped and diffusive. We suggest that cold
Fermi gases trapped inside a tight atomic waveguide offer the opportunity to
measure the spin-drag relaxation rate that controls the broadening of a spin
packet.",0702466v1
2007-03-27,Gauge Field Formulation of Adiabatic Spin Torques,"Previous calculation of spin torques for small-amplitude magnetization
dynamics around a uniformly magnetized state [J. Phys. Soc. Jpn. {\bf 75}
(2006) 113706] is extended here to the case of finite-amplitude dynamics. This
is achieved by introducing an `` adiabatic'' spin frame for conduction
electrons, and the associated SU(2) gauge field. In particular, the Gilbert
damping is shown to arise from the time variation of the spin-relaxation source
terms in this new frame, giving a new physical picture of the damping. The
present method will allow a `` first-principle'' derivation of spin torques
without any assumptions such as rotational symmetry in spin space.",0703705v1
1996-07-23,Quasinormal modes of nearly extreme Reissner-Nordstrom black holes,"We present detailed calculations of the quasinormal modes of
Reissner-Nordstrom black holes. While the first few, slowly damped, modes
depend on the charge of the black hole in a relatively simple way, we find that
the rapidly damped modes show several peculiar features. The higher modes
generally spiral into the value for the extreme black hole as the charge
increases. We also discuss the possible existence of a purely imaginary mode
for the Schwarzschild black hole: Our data suggest that there is a quasinormal
mode that limits to $\omega M = -2i$ as $Q\to 0$.",9607054v1
1996-08-22,Gravitational Ionization: A Chaotic Net in the Kepler System,"The long term nonlinear dynamics of a Keplerian binary system under the
combined influences of gravitational radiation damping and external tidal
perturbations is analyzed. Gravitational radiation reaction leads the binary
system towards eventual collapse, while the external periodic perturbations
could lead to the ionization of the system via Arnold diffusion. When these two
opposing tendencies nearly balance each other, interesting chaotic behavior
occurs that is briefly studied in this paper. It is possible to show that
periodic orbits can exist in this system for sufficiently small damping.
Moreover, we employ the method of averaging to investigate the phenomenon of
capture into resonance.",9608054v1
1999-11-11,Inertial Control of the VIRGO Superattenuator,"The VIRGO superattenuator (SA) is effective in depressing the seismic noise
below the thermal noise level above 4 Hz. On the other hand, the residual
mirror motion associated to the SA normal modes can saturate the dynamics of
the interferometer locking system. This motion is reduced implementing a
wideband (DC-5 Hz) multidimensional control (the so called inertial damping)
which makes use of both accelerometers and position sensors and of a DSP
system. Feedback forces are exerted by coil-magnet actuators on the top of the
inverted pendulum. The inertial damping is successful in reducing the mirror
motion within the requirements. The results are presented.",9911044v1
2002-04-29,Schwarzschild black holes and propagation of electromagnetic and gravitational waves,"Disturbing of a spacetime geometry may result in the appearance of an
oscillating and damped radiation - the so-called quasinormal modes. Their
periods of oscillations and damping coefficients carry unique information about
the mass and the angular momentum, that would allow one to identify the source
of the gravitational field. In this talk we present recent bounds on the
diffused energy, applicable to the Schwarzschild spacetime, that give also
rough estimates of the energy of excited quasinormal modes.",0204086v1
2002-10-30,Massive charged scalar field in a Reissner-Nordstrom black hole background: quasinormal ringing,"We compute characteristic (quasinormal) frequencies corresponding to decay of
a massive charged scalar field in a Reissner-Nordstrom black hole background.
It proves that, contrary to the behavior at very late times, at the stage of
quasinormal ringing the neutral perturbations will damp slower than the charged
ones. In the limit of the extremal black hole the damping rate of charged and
neutral perturbations coincides. Possible connection of this with the critical
collapse in a massive scalar electrodynamics is discussed.",0210105v3
2003-03-20,Dirac Quasi-Normal Modes in Schwarzschild Black Hole Spacetimes,"We evaluate both the massless and the massive Dirac quasi-normal mode
frequencies in the Schwarzschild black hole spacetime using the WKB
approximation. For the massless case, we find that, similar to those for the
integral spin fields, the real parts of the frequencies increase with the
angular momentum number $\kappa$, while the imaginary parts or the dampings
increase with the mode number $n$ for fixed $\kappa$. For the massive case, the
oscillation frequencies increase with the mass $m$ of the field, while the
dampings decrease. Fields with higher masses will therefore decay more slowly.",0303078v1
2003-07-31,Effects of electrical charging on the mechanical Q of a fused silica disk,"We report on the effects of an electrical charge on mechanical loss of a
fused silica disk. A degradation of Q was seen that correlated with charge on
the surface of the sample. We examine a number of models for charge damping,
including eddy current damping and loss due to polarization. We conclude that
rubbing friction between the sample and a piece of dust attracted by the
charged sample is the most likely explanation for the observed loss.",0308001v1
2004-09-15,Rippled Cosmological Dark Matter from Damped Oscillating Newton Constant,"Let the reciprocal Newton 'constant' be an apparently non-dynamical
Brans-Dicke scalar field damped oscillating towards its General Relativistic
VEV. We show, without introducing additional matter fields or dust, that the
corresponding cosmological evolution averagely resembles, in the Jordan frame,
the familiar dark radiation -> dark matter -> dark energy domination sequence.
The fingerprints of our theory are fine ripples, hopefully testable, in the FRW
scale factor; they die away at the General Relativity limit. The possibility
that the Brans-Dicke scalar also serves as the inflaton is favorably examined.",0409059v2
2004-10-06,Thermoelastic-damping noise from sapphire mirrors in a fundamental-noise-limited interferometer,"We report the first high-precision interferometer using large sapphire
mirrors, and we present the first direct, broadband measurements of the
fundamental thermal noise in these mirrors. Our results agree well with the
thermoelastic-damping noise predictions of Braginsky, et al. [Phys. Lett. A
264, 1(1999)] and Cerdonio, et al.[Phys. Rev. D 63, 082003 (2001)], which have
been used to predict the astrophysical reach of advanced interferometric
gravitational wave detectors.",0410028v1
2004-10-28,Gravitational waves from neutron stars described by modern EOS,"The frequencies and damping times of neutron star (and quark star)
oscillations have been computed using the most recent equations of state
available in the literature. We find that some of the empirical relations that
connect the frequencies and damping times of the modes to the mass and radius
of the star, and that were previously derived in the literature need to be
modified.",0410140v1
2005-06-08,Resonant growth of stellar oscillations by incident gravitational waves,"Stellar oscillation under the combined influences of incident gravitational
wave and radiation loss is studied in a simple toy model. The star is
approximated as a uniform density ellipsoid in the Newtonian gravity including
radiation damping through quadrupole formula. The time evolution of the
oscillation is significantly controlled by the incident wave amplitude $h$,
frequency $\nu$ and damping time $\tau$. If a combination $ h \nu \tau $
exceeds a threshold value, which depends on the resonance mode, the resonant
growth is realized.",0506047v1
2006-11-28,Massive scalar field quasinormal modes of a Schwarzschild black hole surrounded by quintessence,"We present the quasinormal frequencies of the massive scalar field in the
background of a Schwarzchild black hole surrounded by quintessence with the
third-order WKB method. The mass of the scalar field $u$ plays an important
role in studying the quasinormal frequencies, the real part of the frequencies
increases linearly as mass $u$ increases, while the imaginary part in absolute
value decreases linearly which leads to damping more slowly and the frequencies
having a limited value. Moreover, owing to the presence of the quintessence,
the massive scalar field damps more slowly.",0611146v2
1992-09-24,Non-Abelian Boltzmann Equation for Mixing and Decoherence,"We consider particle oscillations and their damping in second-quantized form.
We find that the damping or ""decoherence"" may be described by a Boltzmann-like
collision integral with ""non-abelian blocking factors"" (fermions). Earlier
results are generalized in that the momentum degrees of freedom are included
and that the mixing equations become intrinsically non-linear at high
densities.",9209276v1
1993-06-03,The heavy fermion damping rate puzzle,": We examine again the problem of the damping rate of a moving heavy fermion
in a hot plasma within the resummed perturbative theory of Pisarski and
Braaten. The ansatz for its evaluation which relates it to the imaginary part
of the fermion propagator pole in the framework of a self-consistent approach
is critically analyzed. As already pointed out by various authors, the only way
to define the rate is through additional implementation of magnetic screening.
We show in detail how the ansatz works in this case and where we disagree with
other authors. We conclude that the self-consistent approach is not
satisfactory.",9306219v1
1993-09-03,Damping Rate of a Fermion in a Medium,"We examine the relation between the damping rate of a massless, chiral
fermion that propagates in a medium, and the rate $\Gamma$ of approach to
equilibrium. It is proven that these quantities are equal, by showing that they
are given by the same formula in terms of the imaginary part of the self-energy
evaluated at the energy of the propagating fermion mode. This result is valid
provided $\Gamma$ is defined by using the appropriate wave functions of the
mode.",9309225v2
1994-03-22,On the Damping Rate of a Fast Fermion in Hot QED,"The self-consistent determination of the damping rate of a fast moving
fermion in a hot QED plasma is reexamined. We argue how a detailed
investigation of the analytic properties of the retarded fermion Green's
function motivated by the cutting rules at finite temperature may resolve
ambiguities related to the proper definition of the mass-shell condition.",9403335v1
1994-09-12,Fermion damping rate in a hot medium,"In principle every excitation acquires a finite lifetime in a hot system.
This nonzero spectral width is calculated self-consistently for massive
fermions coupled to massless scalar, vector and pseudoscalar bosons. It is
shown that the self-consistent summation of the corresponding Fock diagram for
fermions eliminates all infrared divergences although the bosons are not
screened at all. Our solutions for the fermion damping rate are analytical in
the coupling constant, but not analytical in the temperature parameter around
T=0.",9409280v2
1994-09-22,Lyapunov Exponent and Plasmon Damping Rate in Nonabelian Gauge Theories,"We explain why the maximal positive Lyapunov exponent of classical SU($N$)
gauge theory coincides with (twice) the damping rate of a plasmon at rest in
the leading order of thermal gauge theory. [This is a substantially revised and
expanded version of the manuscript.]",9409392v2
1994-12-20,Baryogenesis and damping in nonminimal electroweak models,"We study the effect of damping on the generation of baryon asymmetry of the
Universe in the standard model of the eletroweak theory with simple extensions
of the Higgs sector. The propagation of quarks of masses up to about 5 GeV are
considered, taking into account their markedly different dispersion relations
due to interaction with the hot electroweak plasma. It is argued that the
contribution of the b quark can be comparable to that of the t quark calculated
earlier.",9412330v1
1998-10-07,Classical Kinetic Theory of Landau Damping for Self-interacting Scalar Fields in the Broken Phase,"The classical kinetic theory of one-component self-interacting scalar fields
is formulated in the broken symmetry phase and applied to the phenomenon of
Landau damping. The domain of validity of the classical approach is found by
comparing with the result of a 1-loop quantum calculation.",9810278v2
1999-08-02,Plasma wave instabilities induced by neutrinos,"Quantum field theory is applied to study the interaction of an electron
plasma with an intense neutrino flux. A connection is established between the
field theory results and classical kinetic theory. The dispersion relation and
damping rate of the plasma longitudinal waves are derived in the presence of
neutrinos. It is shown that Supernova neutrinos are never collimated enough to
cause non-linear effects associated with a neutrino resonance. They only induce
neutrino Landau damping, linearly proportional to the neutrino flux and
$G_{\mathrm{F}}^{2}$.",9908206v2
1999-09-27,Radiation Damping at a Bubble Wall,"The first order phase transition proceeds via nucleation and growth of true
vacuum bubbles. When charged particles collide with the bubble they could
radiate electromagnetic wave. We show that, due to an energy loss of the
particles by the radiation, the damping pressure acting on the bubble wall
depends on the velocity of the wall even in a thermal equilibrium state.",9909521v1
1999-10-08,Lifetime of Collective Isospin Rotations of a Quantum Meson Field,"We calculate the lifetime of the collective isospin rotating solutions which
have been found recently in the case a quantum N-component meson field with
exact O(N) symmetry. For this purpose we take into account the small breaking
of the O(N) symmetry associated to the non vanishing mass of the pion. This
term induces a coupling between collective rotations and intrinsic meson
excitations. We evaluate the associated damping time in the framework of linear
response theory. We find damping times of the order of 100 fm/c, i.e.
substantially longer than reaction times.",9910276v1
2000-02-08,Finite pion width effects on the rho-meson and di-lepton spectra,"Within a field theoretical model where all damping width effects are treated
self-consistently we study the changes of the spectral properties of rho-mesons
due to the finite damping width of the pions in dense hadronic matter at finite
temperature. The corresponding effects in the di-lepton yields are presented.
Some problems concerning the self consistent treatment of vector or gauge
bosons are discussed.",0002087v1
2000-08-31,Damping of very soft moving quarks in high-temperature QCD,"We determine the analytic expression of the damping rates for very soft
moving quarks in an expansion to second order in powers of their momentum in
the context of QCD at high temperature. The calculation is performed using the
hard-thermal-loop-summed perturbation scheme. We describe the range of validity
of the expansion and make a comparison with other calculations, particularly
those using a magnetic mass as a shield from infrared sensitivity. We discuss
the possible occurrence of infrared divergences in our results and argue that
they are due to magnetic sensitivity.",0008335v1
2000-09-27,Damping of the HERA effect in DIS?,"The drastic rise of the proton structure function F_2(x,Q^2) when the
Bj\""orken variable x decreases, seen at HERA for a large span of Q^2, negative
values for the 4-momentum transfer, may be damped when Q^2 increases beyond
several hundreds GeV^2. A new data analysis and a comparison with recent models
for the proton structure function is proposed to discuss this phenomenon in
terms of the derivative \partial ln F_2(x,Q^2)/\partial ln(1/x).",0009313v2
2001-12-13,Time evolution in linear response: Boltzmann equations and beyond,"In this work a perturbative linear response analysis is performed for the
time evolution of the quasi-conserved charge of a scalar field. One can find
two regimes, one follows exponential damping, where the damping rate is shown
to come from quantum Boltzmann equations. The other regime (coming from
multiparticle cuts and products of them) decays as power law. The most
important, non-oscillating contribution in our model comes from a 4-particle
intermediate state and decays as 1/t^3. These results may have relevance for
instance in the context of lepton number violation in the Early Universe.",0112188v1
2002-04-26,Oscillation damping of chiral string loops,"Chiral cosmic string loop tends to the stationary (vorton) configuration due
to the energy loss into the gravitational and electromagnetic radiation. We
describe the asymptotic behaviour of near stationary chiral loops and their
fading to vortons. General limits on the gravitational and electromagnetic
energy losses by near stationary chiral loops are found. For these loops we
estimate the oscillation damping time. We present solvable examples of
gravitational radiation energy loss by some chiral loop configurations. The
analytical dependence of string energy with time is found in the case of the
chiral ring with small amplitude radial oscillations.",0204304v1
2002-09-21,Infrared Sensitivity in Damping Rate for Very Soft Moving Fermions in Finite Temperature QED,"We calculate the fermion damping rate to second order in powers of the
external momentum $p$ in the context of QED at finite temperature using the
hard-thermal-loop (HTL) summation scheme. We find that the coefficient of order
$p^{2}$ is divergent in the infrared whereas the two others are finite. This
result suggests that the htl-based pertubation is infrared sensitive at
next-to-leading order.",0209246v1
2004-02-06,Critical Behavior of Damping Rate for Plasmon with Finite Momentum in φ^4 Theory,"Applying thermal renormalization group (TRG) equations to $\phi^4$ theory
with spontaneous breaking symmetry, we investigate the critical behavior of the
damping rate for the plasmons with finite momentum at the symmetry-restoring
phase transition. From the TRG equation the IR cutoff provided by the external
momentum leads to that the momentum-dependent coupling constant stops running
in the critical region. As the result, the critical slowing down phenomenon
reflecting the inherently IR effect doesn't take place at the critical point
for the plasmon with finite external momentum.",0402069v2
2005-11-22,Ultrasoft Quark Damping in Hot QCD,"We determine the quark damping rates in the context of next-to-leading order
hard-thermal-loop summed perturbation of high-temperature QCD where weak
coupling is assumed. The quarks are ultrasoft. Three types of divergent
behavior are encountered: infrared, light-cone and at specific points
determined by the gluon energies. The infrared divergence persists and is
logarithmic whereas the two others are circumvented.",0511258v1
2006-03-10,Numerical Approach to Multi Dimensional Phase Transitions,"We present an algorithm to analyze numerically the bounce solution of
first-order phase transitions. Our approach is well suited to treat phase
transitions with several fields. The algorithm consists of two parts. In the
first part the bounce solution without damping is determined, in which case
energy is conserved. In the second part the continuation to the physically
relevant case with damping is performed. The presented approach is numerically
stable and easily implemented.",0603081v2
1994-06-22,Damped quantum harmonic oscillator: density operator and related quantities,"A closed expression for the density operator of the damped harmonic
oscillator is extracted from the master equation based on the Lindblad theory
for open quantum systems. The entropy and effective temperature of the system
are subsequently calculated and their temporal behaviour is surveyed by showing
how these quantities relax to their equilibrium values. The entropy for a state
characterized by a Wigner distribution function which is Gaussian in form is
found to depend only on the variance of the distribution function.",9406142v1
1997-05-09,Radiation Damping of a BPS Monopole; an Implication to S-duality,"The radiation reaction of a BPS monopole in the presence of incident
electromagnetic waves as well as massless Higgs waves is analyzed classically.
The reactive forces are compared to those of $W$ boson that is interpreted as a
dual partner of the BPS monopole. It is shown that the damping of acceleration
is dual to each other, while in the case of finite size effects the duality is
broken explicitly. Their implications on the duality are discussed.",9705059v2
1997-07-02,The Asymptotic Method Developed from Weak Turbulent Theory and the Nonlinear Permeability and Damping Rate in QGP,"With asymptotic method developed from weak turbulent theory, the kinetic
equations for QGP are expanded in fluctuation field potential $A^T_\mu $.
Considering the second-order and third-order currents, we derive the nonlinear
permeability tensor function from Yang-Mills field equation, and find that the
third-order current is more important in turbulent theory. The nonlinear
permeability formulae for longitudinal color oscillations show that the
non-Abelian effects are more important than the Abelian-like effects. To
compare with other works, we give the numerical result of the damping rate for
the modes with zero wave vector.",9707052v1
2005-04-07,Continuous area spectrum in regular black hole,"We investigate highly damped quasinormal modes of regular black hole coupled
to nonlinear electrodynamics. Using the WKB approximation combined with
complex-integration technique, we show that the real part of the frequency
disappears in the highly damped limit. If we use the Bohr's correspondence
principle, the area spectrum of this black hole is continuous. We discuss its
implication in the loop quantum gravity.",0504059v2
2005-05-16,Supersymmetrization of the Radiation Damping,"We construct a supersymmetrized version of the model to the radiation damping
\cite{03} introduced by the present authors \cite{ACWF}. We dicuss its
symmetries and the corresponding conserved Noether charges. It is shown this
supersymmetric version provides a supersymmetric generalization of the Galilei
algebra obtained in \cite{ACWF}. We have shown that the supersymmetric action
can be splited into dynamically independent external and internal sectors.",0505142v1
1999-08-16,Topological Entropy and epsilon-Entropy for Damped Hyperbolic Equations,"We study damped hyperbolic equations on the infinite line. We show that on
the global attracting set $G$ the $\epsilon$-entropy (per unit length) exists
in the topology of $W^{1,\infty}$. We also show that the topological entropy
per unit length of $G$ exists. These results are shown using two main
techniques: Bounds in bounded domains in position space and for large momenta,
and a novel submultiplicativity argument in $W^{1,\infty}$.",9908080v1
2003-11-28,Uniform stability of damped nonlinear vibrations of an elastic string,"Here we are concerned about uniform stability of damped nonlinear transverse
vibrations of an elastic string fixed at its two ends. The vibrations governed
by nonlinear integro-differential equation of Kirchoff type, is shown to
possess energy uniformly bounded by exponentially decaying function of time.
The result is achieved by considering an energy-like Lyapunov functional for
the system.",0311527v1
2005-07-06,On stability and stabilization of elastic systems by time-variant feedback,"We study a class of elastic systems described by a (hyperbolic) partial
differential equation. Our working example is the equation of a vibrating
string subject to linear disturbance. The main goal is to establish conditions
for stabilization and asymptotic stabilization by applying a fast oscillating
control to the string. In the first situation studied we assume that system is
subject to a damping force; next we consider the system without damping. We
extend the tools of high-order averaging and of chronological calculus for
studying stability of this distributed parameter system.",0507123v1
2006-01-13,Attractors for damped hyperbolic equations on arbitrary unbounded domains,"We prove existence of global attractors for damped hyperbolic equations of
the form $$\aligned \eps u_{tt}+\alpha(x) u_t+\beta(x)u- \sum_{ij}(a_{ij}(x)
u_{x_j})_{x_i}&=f(x,u),\quad x\in \Omega, t\in[0,\infty[, u(x,t)&=0,\quad x\in
\partial \Omega, t\in[,\infty[.\endaligned$$ on an unbounded domain $\Omega$,
without smoothness assumptions on $\beta(\cdot)$, $a_{ij}(\cdot)$, $f(\cdot,u)$
and $\partial\Omega$, and $f(x,\cdot)$ having critical or subcritical growth.",0601319v3
2007-02-07,Finite time blow-up results for the damped wave equations with arbitrary initial energy in an inhomogeneous medium,"In this paper we consider the long time behavior of solutions of the initial
value problem for the damped wave equation of the form \begin{eqnarray*}
u_{tt}-\rho(x)^{-1}\Delta u+u_t+m^2u=f(u) \end{eqnarray*} with some $\rho(x)$
and $f(u)$ on the whole space $\R^n$ ($n\geq 3$).
  For the low initial energy case, which is the non-positive initial energy,
based on concavity argument we prove the blow up result. As for the high
initial energy case, we give out sufficient conditions of the initial datum
such that the corresponding solution blows up in finite time.",0702190v1
2007-03-09,Analyticity and Riesz basis property of semigroups associated to damped vibrations,"Second order equations of the form $z'' + A_0 z + D z'=0$ in an abstract
Hilbert space are considered. Such equations are often used as a model for
transverse motions of thin beams in the presence of damping. We derive various
properties of the operator matrix $A$ associated with the second order problem
above. We develop sufficient conditions for analyticity of the associated
semigroup and for the existence of a Riesz basis consisting of eigenvectors and
associated vectors of $A$ in the phase space.",0703247v1
2007-03-21,Existence and asymptotic behavior of $C^1$ solutions to the multidimensional compressible Euler equations with damping,"In this paper, the existence and asymptotic behavior of $C^1$ solutions to
the multidimensional compressible Euler equations with damping on the framework
of Besov space are considered. We weaken the regularity requirement of the
initial data, and improve the well-posedness results of Sideris-Thomases-Wang
(Comm.P.D.E. 28 (2003) 953). The global existence lies on a crucial a-priori
estimate which is proved by the spectral localization method. The main analytic
tools are the Littlewood-Paley decomposition and Bony's para-product formula.",0703621v1
2000-12-22,The Vlasov-Poisson system with radiation damping,"We set up and analyze a model of radiation damping within the framework of
continuum mechanics, inspired by a model of post-Newtonian hydrodynamics due to
Blanchet, Damour and Schaefer. In order to simplify the problem as much as
possible we replace the gravitational field by the electromagnetic field and
the fluid by kinetic theory. We prove that the resulting system has a
well-posed Cauchy problem globally in time for general initial data and in all
solutions the fields decay to zero at late times. In particular, this means
that the model is free from the runaway solutions which frequently occur in
descriptions of radiation reaction.",0012041v1
2003-01-17,Quantum mechanics of damped systems,"We show that the quantization of a simple damped system leads to a
self-adjoint Hamiltonian with a family of complex generalized eigenvalues. It
turns out that they correspond to the poles of energy eigenvectors when
continued to the complex energy plane. Therefore, the corresponding generalized
eigenvectors may be interpreted as resonant states. We show that resonant
states are responsible for the irreversible quantum dynamics of our simple
model.",0301024v3
2003-07-23,Quantum Mechanics of Damped Systems II. Damping and Parabolic Potential Barrier,"We investigate the resonant states for the parabolic potential barrier known
also as inverted or reversed oscillator. They correspond to the poles of
meromorphic continuation of the resolvent operator to the complex energy plane.
As a byproduct we establish an interesting relation between parabolic cylinder
functions (representing energy eigenfunctions of our system) and a class of
Gel'fand distributions used in our recent paper.",0307047v1
2001-07-02,Pattern formation and localization in the forced-damped FPU lattice,"We study spatial pattern formation and energy localization in the dynamics of
an anharmonic chain with quadratic and quartic intersite potential subject to
an optical, sinusoidally oscillating field and a weak damping. The
zone-boundary mode is stable and locked to the driving field below a critical
forcing that we determine analytically using an approximate model which
describes mode interactions. Above such a forcing, a standing modulated wave
forms for driving frequencies below the band-edge, while a ``multibreather''
state develops at higher frequencies. Of the former, we give an explicit
approximate analytical expression which compares well with numerical data. At
higher forcing space-time chaotic patterns are observed.",0107002v1
2003-06-16,On the influence of noise on chaos in nearly Hamiltonian systems,"The simultaneous influence of small damping and white noise on Hamiltonian
systems with chaotic motion is studied on the model of periodically kicked
rotor. In the region of parameters where damping alone turns the motion into
regular, the level of noise that can restore the chaos is studied. This
restoration is created by two mechanisms: by fluctuation induced transfer of
the phase trajectory to domains of local instability, that can be described by
the averaging of the local instability index, and by destabilization of motion
within the islands of stability by fluctuation induced parametric modulation of
the stability matrix, that can be described by the methods developed in the
theory of Anderson localization in one-dimensional systems.",0306024v1
2003-07-30,Faraday Wave Pattern Selection Via Multi-Frequency Forcing,"We use symmetry considerations to investigate how damped modes affect pattern
selection in multi-frequency forced Faraday waves. We classify and tabulate the
most important damped modes and determine how the corresponding resonant triad
interactions depend on the forcing parameters. The relative phase of the
forcing terms may be used to enhance or suppress the nonlinear interactions. We
compare our predictions with numerical results and discuss their implications
for recent experiments. Our results suggest how to design multi-frequency
forcing functions that favor chosen patterns in the lab.",0307056v1
2004-10-11,Nodal two-dimensional solitons in nonlinear parametric resonance,"The parametrically driven damped nonlinear Schr\""odinger equation serves as
an amplitude equation for a variety of resonantly forced oscillatory systems on
the plane. In this note, we consider its nodal soliton solutions. We show that
although the nodal solitons are stable against radially-symmetric perturbations
for sufficiently large damping coefficients, they are always unstable to
azimuthal perturbations. The corresponding break-up scenarios are studied using
direct numerical simulations. Typically, the nodal solutions break into
symmetric ""necklaces"" of stable nodeless solitons.",0410012v1
2004-10-21,Stabilization mechanism for two-dimensional solitons in nonlinear parametric resonance,"We consider a simple model system supporting stable solitons in two
dimensions. The system is the parametrically driven damped nonlinear
Schr\""odinger equation, and the soliton stabilises for sufficiently strong
damping. The purpose of this note is to elucidate the stabilisation mechanism;
we do this by reducing the partial differential equation to a
finite-dimensional dynamical system. Our conclusion is that the negative
feedback loop occurs via the enslaving of the soliton's phase, locked to the
driver, to its amplitude and width.",0410044v1
2006-01-14,Vibration of the Duffing Oscillator: Effect of Fractional Damping,"We have applied the Melnikov criterion to examine a global homoclinic
bifurcation and transition to chaos in a case of the Duffing system with
nonlinear fractional damping and external excitation.
  Using perturbation methods we have found a critical forcing amplitude above
which the system may behave chaotically.
  The results have been verified by numerical simulations using standard
nonlinear tools as
  Poincare maps and a Lyapunov exponent. Above the critical Melnikov amplitude
$\mu_c$, which is the sufficient condition of a global homoclinic bifurcation,
we have observed the region with a transient chaotic motion.",0601033v1
2006-10-22,Response of a Magneto-Rheological Fluid Damper Subjected to Periodic Forcing in a High Frequency Limit,"We explored vibrations of a single-degree of freedom oscillator with a
magneto-rheological damper subjected to kinematic excitations. Using fast and
slow scales decoupling procedure we derived an effective damping coefficient in
the limit of high frequency excitation. Damping characteristics, as functions
of velocity, change considerably especially by terminating the singular
non-smoothness points. This effect was more transparent for a larger control
parameter which was defined as the product of the excitation amplitude and its
frequency.",0610055v1
2006-11-02,Solitons in strongly driven discrete nonlinear Schrödinger-type models,"Discrete solitons in the Ablowitz-Ladik (AL) and discrete nonlinear
Schr\""odinger (DNLS) equations with damping and strong rapid drive are
investigated. The averaged equations have the forms of the parametric AL and
DNLS equations. A new type of parametric bright discrete soliton and cnoidal
waves are found and the stability properties are analyzed. The analytical
predictions of the perturbed inverse scattering transform are confirmed by the
numerical simulations of the AL and DNLS equations with rapidly varying drive
and damping.",0611004v1
2006-11-26,On the Lagrangian and Hamiltonian description of the damped linear harmonic oscillator,"Using the modified Prelle- Singer approach, we point out that explicit time
independent first integrals can be identified for the damped linear harmonic
oscillator in different parameter regimes. Using these constants of motion, an
appropriate Lagrangian and Hamiltonian formalism is developed and the resultant
canonical equations are shown to lead to the standard dynamical description.
Suitable canonical transformations to standard Hamiltonian forms are also
obtained. It is also shown that a possible quantum mechanical description can
be developed either in the coordinate or momentum representations using the
Hamiltonian forms.",0611048v1
1992-12-14,Microscopic Origin of Quantum Chaos in Rotational Damping,"The rotational spectrum of $^{168}$Yb is calculated diagonalizing different
effective interactions within the basis of unperturbed rotational bands
provided by the cranked shell model. A transition between order and chaos
taking place in the energy region between 1 and 2 MeV above the yrast line is
observed, associated with the onset of rotational damping. It can be related to
the higher multipole components of the force acting among the unperturbed
rotational bands.",9212005v1
1996-12-17,Damping mechanisms of the Delta resonance in nuclei,"The damping mechanisms of the Delta(1232) resonance in nuclei are studied by
analyzing the quasi-free decay reactions 12C(pi+,pi+ p)11B and 12C(3He,t pi+
p)11B and the 2p emission reactions 12C(pi+,pp)10B and 12C(3He,t pp)10B. The
coincidence cross sections are calculated within the framework of the
isobar-hole model. It is found that the 2p emission process induced by the
decay of the Delta resonance in the nucleus can be consistently described by a
pi+rho+g' model for the Delta+N -> N+N decay interaction.",9612046v1
1997-11-08,Cooperative damping mechanism of the resonance in the nuclear photoabsorption,"We propose a resonance damping mechanism to explain the disappearance of the
peaks around the position of the resonances higher than the $\Delta$ resonance
in the nuclear photoabsorption. This phenomenon is understood by taking into
account the cooperative effect of the collision broadening of $\Delta$ and
$N^{*}$, the pion distortion and the interference in the two-pion
photoproduction processes in the nuclear medium.",9711017v4
1998-05-27,Collisional Damping of Nuclear Collective Vibrations in a Non-Markovian Transport Approach,"A detailed derivation of the collisional widths of collective vibrations is
presented in both quantal and semi-classical frameworks by considering the
linearized limits of the extended TDHF and the BUU model with a non-Markovian
binary collision term. Damping widths of giant dipole and giant quadrupole
excitations are calculated by employing an effective Skyrme force, and the
results are compared with GDR measurements in Lead and Tin nuclei at finite
temperature.",9805050v1
1999-07-06,Probing the width of compound states with rotational gamma rays,"The intrinsic width of (multiparticle-multihole) compound states is an
elusive quantity, of difficult direct access, as it is masked by damping
mechanisms which control the collective response of nuclei. Through microscopic
cranked shell model calculations, it is found that the strength function
associated with two-dimensional gamma-coincidence spectra arising from
rotational transitions between states lying at energies >1 MeV above the yrast
line, exhibits a two-component structure controlled by the rotational (wide
component) and compound (narrow component) damping width. This last component
is found to be directly related to the width of the multiparticle-multihole
autocorrelation function.",9907016v1
1999-07-09,Color plasma oscillation in strangelets,"The dispersion relation and damping rate of longitudinal color plasmons in
finite strange quark matter (strangelets) are evaluated in the limits of weak
coupling, low temperature, and long wavelength. The property of the QCD vacuum
surrounding a strangelet makes the frequency of the plasmons nearly the same as
the color plasma frequency of bulk matter. The plasmons are damped by their
coupling with individual excitations of particle-hole pairs of quarks, of which
the energy levels are discretized by the boundary. For strangelets of
macroscopic size, the lifetime of the plasmons is found to be proportional to
the size, as in the case of the usual plasma oscillations in metal
nanoparticles.",9907039v1
1999-09-21,On the Collisional Damping of Giant Dipole Resonance,"Collisional damping widths of giant dipole excitations are calculated in
Thomas-Fermi approximation by employing the microscopic in-medium
cross-sections of Li and Machleidt and the phenomenological Gogny force. The
results obtained in both calculations compare well, but account for about
25-35% of the observed widths in $^{120}Sn$ and $^{208}Pb$ at finite
temperatures.",9909057v1
2000-01-09,Strongly damped nuclear collisions: zero or first sound ?,"The relaxation of the collective quadrupole motion in the initial stage of a
central heavy ion collision at beam energies $E_{lab}=5\div20$ AMeV is studied
within a microscopic kinetic transport model. The damping rate is shown to be a
non-monotonic function of E_{lab} for a given pair of colliding nuclei. This
fact is interpreted as a manifestation of the zero-to-first sound transition in
a finite nuclear system.",0001016v1
2002-11-18,Collision damping in the pi 3He -> d'N reaction near the threshold,"We present a simple quantum mechanical model exploiting the optical potential
approach for the description of collision damping in the reaction pi 3He -> d'N
near the threshold, which recently has been measured at TRIUMF. The influence
of the open d'N -> NNN channel is taken into account. It leads to a suppression
factor of about ten in the d' survival probability. Applications of the method
to other reactions are outlined.",0211050v1
2003-03-14,Pion damping width from SU(2) x SU(2) NJL model,"Within the framework of the NJL model, we investigate the modification of the
pion damping width in a hot pion gas for temperatures ranging from 0 to 180
MeV. The pion is found to broaden noticeably at T > 60 MeV. Near the chiral
phase transition T ~ 180 MeV, the pion width is saturated and amounts to 70
MeV. The main contribution to the width comes from pion-pion collisions. Other
contributions are found negligibly small.",0303034v1
2004-06-09,Damped collective motion of isolated many body systems within a variational approach to functional integrals,"Two improvements with respect to previous formulations are presented for the
calculation of the partition function $\mathcal{Z}$ of small, isolated and
interacting many body systems. By including anharmonicities and employing a
variational approach quantum effects can be treated even at very low
temperatures. A method is proposed of how to include collisional damping.
Finally, our approach is applied to the calculation of the decay rate of
metastable systems.",0406025v1
2004-07-26,Damped collective motion of many body systems: A variational approach to the quantal decay rate,"We address the problem of collective motion across a barrier like encountered
in fission. A formula for the quantal decay rate is derived which bases on a
recently developed variational approach for functional integrals. This formula
can be applied to low temperatures that have not been accessible within the
former PSPA type approach. To account for damping of collective motion one
particle Green functions are dressed with appropriate self-energies.",0407092v2
1997-11-15,Fluctuational phase-flip transitions in parametrically pumped oscillators,"We analyze the rates of noise-induced transitions between period-two
attractors. The model investigated is an underdamped oscillator parametrically
driven by a field at nearly twice the oscillator eigenfrequency. The activation
energy of the transitions is analyzed as a function of the frequency detuning
and field amplitude scaled by the damping and nonlinearity parameters of the
oscillator. The parameter ranges where the system is bi- and tristable are
investigated. Explicit results are obtained in the limit of small damping (or
strong driving), and near bifurcation points.",9711014v1
1999-05-31,Collisionless Damping of Low-Frequency Magnetosonic Pulses in a Two-Ion-Species Plasma,"Low-frequency mangnetosonic pulses in a two-ion-species plasma are studied
theoretically and by simulation with a one-dimensional electromagnetic
simulation code based on a three-fluid model, with particular attention to the
dynamics of minority heavy ions. It is found that heavy ions can gain some
energy from the pulses. Because of this energy transfer, the pulses are damped
even if the plasma is collisionless and pulse propagation is perpendicular to
the magnetic field.",9905059v1
2000-10-17,Bunch Length Measurements at the ATF Damping Ring in April 2000,"This report presents bunch length and energy spread measurements performed in
April 2000 at the ATF Damping Ring, at KEK. Measurements were performed with
the beam on and then off the linear (difference) coupling resonance. Due to
strong intra-beam scattering in the ATF ring, the results depended strongly on
the coupling.",0010043v1
2000-12-21,Phase transition in the collisionless regime for wave-particle interaction,"Gibbs statistical mechanics is derived for the Hamiltonian system coupling
self-consistently a wave to N particles. This identifies Landau damping with a
regime where a second order phase transition occurs. For nonequilibrium initial
data with warm particles, a critical initial wave intensity is found: above it,
thermodynamics predicts a finite wave amplitude in the limit of infinite N;
below it, the equilibrium amplitude vanishes. Simulations support these
predictions providing new insight on the long-time nonlinear fate of the wave
due to Landau damping in plasmas.",0012053v1
2001-09-25,Creep and Mechanical Oscillator Damping,"Although ""friction"" is included in many models of oscillator damping,
including viscous ones applied to the pendulum; they ""miss the mark"" with
regard to a conceptual understanding of the mechanisms responsible for energy
loss. The theory of the present paper corrects some of these misunderstandings
by considering the influence of internal friction which derives from the
structural members of the oscillator through secondary rather than primary
creep. The simple model properly describes the variation of Q with frequency.",0109067v1
2001-11-06,Electromagnetic induction and damping - quantitative experiments using PC interface,"A bar magnet, attached to an oscillating system, passes through a coil
periodically, generating a series of emf pulses. A novel method is described
for the quantitative verification of Faraday's law which eliminates all errors
associated with angular measurements, thereby revealing delicate features of
the underlying mechanics. When electromagnetic damping is activated by
short-circuiting the coil, a distinctly linear decay of oscillation amplitude
is surprisingly observed. A quantitative analysis reveals an interesting
interplay of the electromagnetic and mechanical time scales.",0111016v1
2003-08-31,Effects of Bulk Viscosity in Non-linear Bubble Dynamics,"The non-linear bubble dynamics equations in a compressible liquid have been
modified considering the effects of compressibility of both the liquid and the
gas at the bubble interface. A new bubble boundary equation has been derived,
which includes a new term resulted from the liquid bulk viscosity effects. The
influence of this term has been numerically investigated considering the
effects of water vapor and chemical reactions on the bubble evolution. The
results clearly indicate that the new term has an important damping role at the
collapse, so that its consideration decreases the amplitude of the bubble
rebounds after the collapse. This damping feature is more remarkable for higher
deriving pressures.",0309012v1
2004-04-30,"On violation of the Robinson's damping criterion and enhanced cooling of ion, electron and muon beams in storage rings","Limits of applicability of the Robinson's damping criterion and the problem
of enhanced cooling of particle beams in storage rings beyond the criterion are
discussed.",0404142v6
2004-12-28,"Electron Bernstein waves in spherical tokamak plasmas with ""magnetic wells""","In addition to traditional regimes with monotonously increasing magnetic
field, regimes with ""magnetic wells"" also occur in spherical tokamaks (STs).
The magnetic field profile inversion modifies significantly the whole picture
of the wave propagation and damping. Since the magnetic wells may become quite
common with further improvement of ST performance, analysis of such
configurations is of interest for assessment of EBW plasma heating an CD
perspectives. In this paper the basic features of the EBWs propagation and
damping for the second cyclotron harmonic in a slab model are considered.",0412173v1
2005-02-10,Modulational instabilities in Josephson oscillations of elongated coupled condensates,"We study the Josephson oscillations of two coupled elongated condensates.
Linearized calculations show that the oscillating mode uniform over the length
of the condensates (uniform Josephson mode) is unstable : modes of non zero
longitudinal momentum grow exponentially. In the limit of strong atom
interactions, we give scaling laws for the instability time constant and
unstable wave vectors. Beyond the linearized approach, numerical calculations
show a damped recurrence behavior : the energy in the Josephson mode presents
damped oscillations. Finally, we derive conditions on the confinement of the
condensates to prevent instabilities.",0502050v3
2005-08-16,Creep-Enhanced Low-Frequency Sensitivity of Seismometers,"The frequency response of a seismometer is typically assumed to be the
textbook case of a viscous damped, simple harmonic oscillator. Real mechanical
oscillators are not ideal, and the damping at low frequencies, due to internal
friction, is presently too poorly understood to describe from first principles.
Even if the low-level motions were smooth (which they are not), the mean
position of a seismic mass changes because of creep and creep recovery. This
article shows that secondary creep can actually serve to increase the
sensitivity of a seismometer at low frequencies.",0508105v1
2006-06-22,Looking for a time independent Hamiltonian of a dynamical system,"In this paper we introduce a method for finding a time independent
Hamiltonian of a given dynamical system by canonoid transformation. We also
find a condition that the system should satisfy to have an equivalent time
independent formulation. We study the example of damped oscillator and give the
new time independent Hamiltonian for it, which has the property of tending to
the standard Hamiltonian of the harmonic oscillator as damping goes to zero.",0606197v2
1996-02-27,Effects of Loss and Decoherence on a Simple Quantum Computer,"We investigate the impact of loss (amplitude damping) and decoherence (phase
damping) on the performance of a simple quantum computer which solves the
one-bit Deutsch problem. The components of this machine are beamsplitters and
nonlinear optical Kerr cells, but errors primarily originate from the latter.
We develop models to describe the effect of these errors on a quantum optical
Fredkin gate. The results are used to analyze possible error correction
strategies in a complete quantum computer. We find that errors due to loss can
be avoided perfectly by appropriate design techniques, while decoherence can be
partially dealt with using projective error correction.",9602018v1
1996-11-25,The Quantum state diffusion model and the driven damped nonlinear oscillator,"We consider a driven damped anharmonic oscillator which classically leads to
a bistable steady state and to hysteresis. The quantum counterpart for this
system has an exact analytical solution in the steady state which does not
display any bistability or hysteresis. We use quantum state diffusion theory to
describe this system and to provide a new perspective on the lack of hysteresis
in the quantum regime so as to study in detail the quantum to classical
transition. The analysis is also relevant to measurements of a single
periodically driven electron in a Penning trap where hysteresis has been
observed.",9611044v1
1997-12-02,Prevention of dissipation with two particles,"An error prevention procedure based on two-particle encoding is proposed for
protecting an arbitrary unknown quantum state from dissipation, such as phase
damping and amplitude damping. The schemes, which exhibits manifestation of the
quantum Zeno effect, is effective whether quantum bits are decohered
independently or cooperatively. We derive the working condition of the scheme
and argue that this procedure has feasible practical implementation.",9712005v1
1998-02-23,Caldirola-Kanai Oscillator in Classical Formulation of Quantum Mechanics,"The quadrature distribution for the quantum damped oscillator is introduced
in the framework of the formulation of quantum mechanics based on the
tomography scheme. The probability distribution for the coherent and Fock
states of the damped oscillator is expressed explicitly in terms of Gaussian
and Hermite polynomials, correspondingly.",9802057v1
1999-03-22,Decoherence - Fluctuation Relation and Measurement Noise,"We discuss fluctuations in the measurement process and how these fluctuations
are related to the dissipational parameter characterising quantum damping or
decoherence. On the example of the measuring current of the variable-barrier or
QPC problem we show there is an extra noise or fluctuation connected with the
possible different outcomes of a measurement. This noise has an enhanced short
time component which could be interpreted as due to ``telegraph noise'' or
``wavefunction collapses''. Furthermore the parameter giving the the strength
of this noise is related to the parameter giving the rate of damping or
decoherence.",9903072v1
1999-07-27,Nonclassical correlations in damped N-solitons,"The quantum statistics of damped higher-order optical solitons are analyzed
numerically, using cumulant-expansion techniques in Gaussian approximation. A
detailed analysis of nonclassical properties in both the time and the frequency
domain is given, with special emphasis on the role of absorption. Highly
nonclassical broadband spectral correlation is predicted.",9907090v2
2001-01-08,Cavity-damping-induced transitions in a driven atom-cavity system,"We investigate the fluorescence spectrum of a two-level atom in a cavity when
the atom is driven by a classical field. We show that forbidden dipole
transitions in the Jaynes-Cummings Ladder structure are induced in the presence
of the cavity damping, which deteriorates the degree of otherwise perfect
destructive interference among the transition channels. With the larger cavity
decay, these transitions are more enhanced.",0101036v1
2001-06-09,Squeezing enhancement by damping in a driven atom-cavity system,"In a driven atom-cavity coupled system in which the two-level atom is driven
by a classical field, the cavity mode which should be in a coherent state in
the absence of its reservoir, can be squeezed by coupling to its reservoir. The
squeezing effect is enhanced as the damping rate of the cavity is increased to
some extent.",0106054v1
2001-08-01,Decoherence-induced wave packet splitting,"We provide an intuitive interpretation of the optical Stern-Gerlach effect
(OSGE) in the dressed-state point of view. We also analyze the effect of atomic
damping in an experiment on the OSGE. We show that the atomic damping also
causes the wave packet splitting, in a non-mechanical fashion, as opposed to
the coherent process that is mechanical.",0108005v1
2001-08-11,A Canonical Approach to the Quantization of the Damped Harmonic Oscillator,"We provide a new canonical approach for studying the quantum mechanical
damped harmonic oscillator based on the doubling of degrees of freedom
approach. Explicit expressions for Lagrangians of the elementary modes of the
problem, characterising both forward and backward time propagations are given.
  A Hamiltonian analysis, showing the equivalence with the Lagrangian approach,
is also done. Based on this Hamiltonian analysis, the quantization of the model
is discussed.",0108055v2
2002-05-09,Implementation of quantum maps by programmable quantum processors,"A quantum processor is a device with a data register and a program register.
The input to the program register determines the operation, which is a
completely positive linear map, that will be performed on the state in the data
register. We develop a mathematical description for these devices, and apply it
to several different examples of processors. The problem of finding a processor
that will be able to implement a given set of mappings is also examined, and it
is shown that while it is possible to design a finite processor to realize the
phase-damping channel, it is not possible to do so for the amplitude-damping
channel.",0205050v1
2002-08-28,Damped Quantum Interference using Stochastic Calculus,"It is shown how the phase-damping master equation, either in Markovian and
nonMarkovian regimes, can be obtained as an averaged random unitary evolution.
This, apart from offering a common mathematical setup for both regimes, enables
us to solve this equation in a straightforward manner just by solving the
Schrodinger equation and taking the stochastic expectation value of its
solutions after an adequate modification. Using the linear entropy as a figure
of merit (basically the loss of quantum coherence) the distinction of four
kinds of environments is suggested.",0208176v1
2002-10-31,Quantum Markov Channels for Qubits,"We examine stochastic maps in the context of quantum optics. Making use of
the master equation, the damping basis, and the Bloch picture we calculate a
non-unital, completely positive, trace-preserving map with unequal damping
eigenvalues. This results in what we call the squeezed vacuum channel. A
geometrical picture of the effect of stochastic noise on the set of pure state
qubit density operators is provided. Finally, we study the capacity of the
squeezed vacuum channel to transmit quantum information and to distribute EPR
states.",0211001v1
2003-01-17,Concurrence and foliations induced by some 1-qubit channels,"We start with a short introduction to the roof concept. An elementary
discussion of phase-damping channels shows the role of anti-linear operators in
representing their concurrence. A general expression for some concurrences is
derived. We apply it to 1-qubit channels of length two, getting induced
foliations of the state space, the optimal decompositions, and the entropy of a
state with respect to these channels. For amplitude-damping channels one
obtains an expression for the Holevo capacity allowing for easy numerical
calculations.",0301088v1
2003-05-19,Statistical Effects in the Multistream Model for Quantum Plasmas,"A statistical multistream description of quantum plasmas is formulated, using
the Wigner-Poisson system as dynamical equations. A linear stability analysis
of this system is carried out, and it is shown that a Landau-like damping of
plane wave perturbations occurs due to the broadening of the background Wigner
function that arises as a consequence of statistical variations of the wave
function phase. The Landau-like damping is shown to suppress instabilities of
the one- and two-stream type.",0305102v1
2003-06-28,Misbelief and misunderstandings on the non--Markovian dynamics of a damped harmonic oscillator,"We use the exact solution for the damped harmonic oscillator to discuss some
relevant aspects of its open dynamics often mislead or misunderstood. We
compare two different approximations both referred to as Rotating Wave
Approximation. Using a specific example, we clarify some issues related to
non--Markovian dynamics, non--Lindblad type dynamics, and positivity of the
density matrix.",0306193v3
2003-11-26,Effective damping in the Raman cooling of trapped ions,"We present a method of treating the interaction of a single three-level ion
with two laser beams. The idea is to apply a unitary transformation such that
the exact transformed Hamiltonian has one of the three levels decoupled for all
values of the detunings. When one takes into account damping, the evolution of
the system is governed by a master equation usually obtained via adiabatic
approximation under the assumption of far-detuned lasers. To go around the
drawbacks of this technique, we use the same unitary transformation to get an
effective master equation.",0311183v1
2004-06-20,Entanglement-assisted classical information capacity of the amplitude damping channel,"In this paper, we calculate the entanglement-assisted classical information
capacity of amplitude damping channel and compare it with the particular mutual
information which is considered as the entanglement-assisted classical
information capacity of this channel in Ref. 6. It is shown that the difference
between them is very small. In addition, we point out that using partial
symmetry and concavity of mutual information derived from dense coding scheme
one can simplify the calculation of entanglement-assisted classical information
capacities for non-unitary-covariant quantum noisy channels.",0406140v1
2004-08-13,Decoherence versus Dynamical Casimir Effect,"By means of two simple examples: phase and amplitude damping, the impact of
decoherence on the dynamical Casimir effect is investigated. Even without
dissipating energy (i.e., pure phase damping), the amount of created particles
can be diminished significantly via the coupling to the environment (reservoir
theory) inducing decoherence. For a simple microscopic model, it is
demonstrated that spontaneous decays within the medium generate those problems
-- Rabi oscillations are far more advantageous in that respect. These findings
are particularly relevant in view of a recently proposed experimental
verification of the dynamical Casimir effect. PACS: 42.50.Lc, 03.65.Yz,
03.70.+k, 42.50.Dv.",0408087v2
2004-10-11,Quantizing the damped harmonic oscillator,"We consider the Fermi quantization of the classical damped harmonic
oscillator (dho). In past work on the subject, authors double the phase space
of the dho in order to close the system at each moment in time. For an
infinite-dimensional phase space, this method requires one to construct a
representation of the CAR algebra for each time. We show that unitary dilation
of the contraction semigroup governing the dynamics of the system is a logical
extension of the doubling procedure, and it allows one to avoid the
mathematical difficulties encountered with the previous method.",0410078v1
2004-11-18,Drastic effects of damping mechanisms on the third-order optical nonlinearity,"We have investigated the optical response of superradiant atoms, which
undergoes three different damping mechanisms: radiative dissipation
($\gamma_r$), dephasing ($\gamma_d$), and nonradiative dissipation
($\gamma_n$). Whereas the roles of $\gamma_d$ and $\gamma_n$ are equivalent in
the linear susceptibility, the third-order nonlinear susceptibility drastically
depends on the ratio of $\gamma_d$ and $\gamma_n$: When $\gamma_d \ll
\gamma_n$, the third-order susceptibility is essentially that of a single atom.
Contrarily, in the opposite case of $\gamma_d \gg \gamma_n$, the third-order
susceptibility suffers the size-enhancement effect and becomes proportional to
the system size.",0411129v1
2005-01-19,Stabilizing an atom laser using spatially selective pumping and feedback,"We perform a comprehensive study of stability of a pumped atom laser in the
presence of pumping, damping and outcoupling. We also introduce a realistic
feedback scheme to improve stability by extracting energy from the condensate
and determine its effectiveness. We find that while the feedback scheme is
highly efficient in reducing condensate fluctuations, it usually does not alter
the stability class of a particular set of pumping, damping and outcoupling
parameters.",0501101v1
2005-06-11,Quantum damped oscillator II: Bateman's Hamiltonian vs. 2D Parabolic Potential Barrier,"We show that quantum Bateman's system which arises in the quantization of a
damped harmonic oscillator is equivalent to a quantum problem with 2D parabolic
potential barrier known also as 2D inverted isotropic oscillator. It turns out
that this system displays the family of complex eigenvalues corresponding to
the poles of analytical continuation of the resolvent operator to the complex
energy plane. It is shown that this representation is more suitable than the
hyperbolic one used recently by Blasone and Jizba.",0506091v1
2005-06-27,Entanglement of pair cat states and teleportation,"The entanglement of pair cat states in the phase damping channel is studied
by employing the relative entropy of entanglement. It is shown that the pair
cat states can always be distillable in the phase damping channel. Furthermore,
we analyze the fidelity of teleportation for the pair cat states by using joint
measurements of the photon-number sum and phase difference.",0506217v1
2005-07-21,Entanglement versus mixedness for coupled qubits under a phase damping channel,"Quantification of entanglement against mixing is given for a system of
coupled qubits under a phase damping channel. A family of pure initial joint
states is defined, ranging from pure separable states to maximally entangled
state. An ordering of entanglement measures is given for well defined initial
state amount of entanglement.",0507212v2
2005-10-20,Overdamping by weakly coupled environments,"A quantum system weakly interacting with a fast environment usually undergoes
a relaxation with complex frequencies whose imaginary parts are damping rates
quadratic in the coupling to the environment, in accord with Fermi's ``Golden
Rule''. We show for various models (spin damped by harmonic-oscillator or
random-matrix baths, quantum diffusion, quantum Brownian motion) that upon
increasing the coupling up to a critical value still small enough to allow for
weak-coupling Markovian master equations, a new relaxation regime can occur. In
that regime, complex frequencies lose their real parts such that the process
becomes overdamped. Our results call into question the standard belief that
overdamping is exclusively a strong coupling feature.",0510164v1
2006-06-07,"Comment on ""Optimum Quantum Error Recovery using Semidefinite Programming""","In a recent paper ([1]=quant-ph/0606035) it is shown how the optimal recovery
operation in an error correction scheme can be considered as a semidefinite
program. As a possible future improvement it is noted that still better error
correction might be obtained by optimizing the encoding as well. In this note
we present the result of such an improvement, specifically for the four-bit
correction of an amplitude damping channel considered in [1]. We get a strict
improvement for almost all values of the damping parameter. The method (and the
computer code) is taken from our earlier study of such correction schemes
(quant-ph/0307138).",0606059v1
2006-09-19,Quantum master equations from classical Lagrangians with two stochastic forces,"We show how a large family of master equations, describing quantum Brownian
motion of a harmonic oscillator with translationally invariant damping, can be
derived within a phenomenological approach, based on the assumption that an
environment can be simulated by two classical stochastic forces. This family is
determined by three time-dependent correlation functions (besides the frequency
and damping coefficients), and it includes as special cases the known master
equations, whose dissipative part is bilinear with respect to the operators of
coordinate and momentum.",0609144v3
2006-10-16,Local noise can enhance entanglement teleportation,"Recently we have considered two-qubit teleportation via mixed states of four
qubits and defined the generalized singlet fraction. For single-qubit
teleportation, Badziag {\em et al.} [Phys. Rev. A {\bf 62}, 012311 (2000)] and
Bandyopadhyay [Phys. Rev. A {\bf 65}, 022302 (2002)] have obtained a family of
entangled two-qubit mixed states whose teleportation fidelity can be enhanced
by subjecting one of the qubits to dissipative interaction with the environment
via an amplitude damping channel. Here, we show that a dissipative interaction
with the local environment via a pair of time-correlated amplitude damping
channels can enhance fidelity of entanglement teleportation for a class of
entangled four-qubit mixed states. Interestingly, we find that this enhancement
corresponds to an enhancement in the quantum discord for some states.",0610125v1
2006-11-24,High fidelity transfer of an arbitrary quantum state between harmonic oscillators,"It is shown that by switching a specific time-dependent interaction between a
harmonic oscillator and a transmission line (a waveguide, an optical fiber,
etc.) the quantum state of the oscillator can be transferred into that of
another oscillator coupled to the distant other end of the line, with a
fidelity that is independent of the initial state of both oscillators. For a
transfer time $T$, the fidelity approaches 1 exponentially in $\gamma T$ where
$\gamma$ is a characteristic damping rate. Hence, a good fidelity is achieved
even for a transfer time of a few damping times. Some implementations are
discussed.",0611249v1
2006-12-05,Quantum Brownian motion and the second law of thermodynamics,"We consider a single harmonic oscillator coupled to a bath at zero
temperature. As is well known, the oscillator then has a higher average energy
than that given by its ground state. Here we show analytically that for a
damping model with arbitrarily discrete distribution of bath modes and damping
models with continuous distributions of bath modes with cut-off frequencies,
this excess energy is less than the work needed to couple the system to the
bath, therefore, the quantum second law is not violated. On the other hand, the
second law may be violated for bath modes without cut-off frequencies, which
are, however, physically unrealistic models.",0612038v1
2007-05-08,Minimal qudit code for a qubit in the phase-damping channel,"Using the stabilizer formalism we construct the minimal code into a
D-dimensional Hilbert space (qudit) to protect a qubit against phase damping.
The effectiveness of this code is then studied by means of input-output
fidelity.",0705.1099v3
2007-05-10,Anomalous Diffusion of particles with inertia in external potentials,"Recently a new type of Kramers-Fokker-Planck Equation has been proposed [R.
Friedrich et al. Phys. Rev. Lett. {\bf 96}, 230601 (2006)] describing anomalous
diffusion in external potentials. In the present paper the explicit cases of a
harmonic potential and a velocity-dependend damping are incorporated. Exact
relations for moments for these cases are presented and the asymptotic
behaviour for long times is discussed. Interestingly the bounding potential and
the additional damping by itself lead to a subdiffussive behaviour, while
acting together the particle becomes localized for long times.",0705.1480v1
2007-05-31,Stability of Solutions to Damped Equations with Negative Stiffness,"This article concerns the stability of a model for mass-spring systems with
positive damping and negative stiness. It is well known that when the
coefficients are frozen in time the system is unstable. Here we find conditions
on the variable cofficients to prove stability. In particular, we disprove the
believe that if the eigenvalues of the system change slowly in time the system
remains unstable. We extend some of our results for nonlinear systems.",0705.4670v1
2007-06-13,Polymers in a vacuum,"In a variety of situations, isolated polymer molecules are found in a vacuum
and here we examine their properties. Angular momentum conservation is shown to
significantly alter the average size of a chain and its conservation is only
broken slowly by thermal radiation. The time autocorrelation for monomer
position oscillates with a characteristic time proportional to chain length.
The oscillations and damping are analyzed in detail. Short range repulsive
interactions suppress oscillations and speed up relaxation but stretched chains
still show damped oscillatory time correlations.",0706.2001v1
2007-07-15,Enhancement of Carrier Mobility in Semiconductor Nanostructures by Dielectric Engineering,"We propose a technique for achieving large improvements in carrier mobilities
in 2- and 1-dimensional semiconductor nanostructures by modifying their
dielectric environments. We show that by coating the nanostructures with
high-$\kappa$ dielectrics, scattering from Coulombic impurities can be strongly
damped. Though screening is also weakened, the damping of Coulombic scattering
is much larger, and the resulting improvement in mobilities of carriers can be
as much as an order of magnitude for thin 2D semiconductor membranes, and more
for semiconductor nanowires.",0707.2244v1
2007-07-23,Causal vs. Noncausal Description of Nonlinear Wave Mixing; Resolving the Damping-Sign Controversy,"Frequency-domain nonlinear wave mixing processes may be described either
using response functions whereby the signal is generated after all interactions
with the incoming fields, or in terms of scattering amplitudes where all fields
are treated symetrically with no specific time ordering. Closed Green's
function expressions derived for the two types of signals have different
analytical properties. The recent controversy regarding the sign of radiative
damping in the linear (Kramers Heisenberg) formula is put in a broader context.",0707.3458v1
2007-07-27,Excitation of spin dynamics by spin-polarized current in vortex state disks,"A spin-polarized current with the polarization perpendicular to the plane of
a vortex-state disk results in renormalization of the effective damping for a
given magnetization mode, and the effective damping becomes zero if the current
exceeds a threshold value. The lowest threshold current corresponds to the
lowest frequency vortex gyroscopic mode. For larger values of the current the
dynamic magnetization state is characterized by precession of the vortex around
the dot center with non-small amplitude and higher frequency.",0707.4128v1
2007-09-11,Frequency and damping of the Scissors Mode of a Fermi gas,"We calculate the frequency and damping of the scissors mode in a classical
gas as a function of temperature and coupling strength. Our results show good
agreement with the main features observed in recent measurements of the
scissors mode in an ultracold gas of $^6$Li atoms. The comparison between
theory and experiment involves no fitting parameters and thus allows an
identification of non-classical effects at and near the unitarity limit.",0709.1617v2
2007-09-14,Strong collisionless damping of the low-velocity branch of electromagnetic wave in plasmas with Maxwellian-like electron velocity distribution function,"After approximate replacing of Maxwellian distribution exponent with the
rational polynomial fraction we have obtained precise analytical expression for
and calculated the principal value of logarithmically divergent integral in the
electron wave dispersion equation. At the same time our calculations have shown
the presence of strong collisionless damping of the electromagnetic
low-velocity (electron) wave in plasmas with Maxwellian-like electron velocity
distribution function at some small, of the order of several per cents,
differences from Maxwellian distribution in the main region of large electron
densities, however due to the differences in the distribution tail, where
electron density itself is negligibly small.",0709.2206v1
2007-09-14,"Plasmons, plasminos and Landau damping in a quasiparticle model of the quark-gluon plasma","A phenomenological quasiparticle model is surveyed for 2+1 quark flavors and
compared with recent lattice QCD results. Emphasis is devoted to the effects of
plasmons, plasminos and Landau damping. It is shown that thermodynamic bulk
quantities, known at zero chemical potential, can uniquely be mapped towards
nonzero chemical potential by means of a thermodynamic consistency condition
and a stationarity condition.",0709.2262v2
2007-10-04,Activation of additional energy dissipation processes in the magnetization dynamics of epitaxial chromium dioxide films,"The precessional magnetization dynamics of a chromium dioxide$(100)$ film is
examined in an all-optical pump-probe setup. The frequency dependence on the
external field is used to extract the uniaxial in-plane anisotropy constant.
The damping shows a strong dependence on the frequency, but also on the laser
pump fluency, which is revealed as an important experiment parameter in this
work: above a certain threshold further channels of energy dissipation open and
the damping increases discontinuously. This behavior might stem from spin-wave
instabilities.",0710.0986v2
2007-10-24,Spin dynamics of a trapped spin-1 Bose Gas above the Bose-Einstein transition temperature,"We study collective spin oscillations in a spin-1 Bose gas above the
Bose-Einstein transition temperature. Starting from the Heisenberg equation of
motion, we derive a kinetic equation describing the dynamics of a thermal gas
with the spin-1 degree of freedom. Applying the moment method to the kinetic
equation, we study spin-wave collective modes with dipole symmetry. The dipole
modes in the spin-1 system are found to be classified into the three type of
modes. The frequency and damping rate are obtained as functions of the peak
density. The damping rate is characterized by three relaxation times associated
with collisions.",0710.4419v2
2007-11-19,Nonlinear mode conversion in monodomain magnetic squares,"Modifications of spatial distributions of dynamic magnetization corresponding
to spinwave eigenmodes of magnetic squares subjected to a strong microwave
excitation field have been studied experimentally and theoretically. We show
that an increase of the excitation power leads to a nonlinear generation of
long-wavelength spatial harmonics caused by the nonlinear cross coupling
between the eigenmodes. The analysis of the experimental data shows that this
process is mainly governed by the action of the nonlinear spin-wave damping.
This conclusion is further supported by the numerical calculations based on the
complex Ginzburg-Landau equation phenomenologically taking into account the
nonlinear damping.",0711.2872v1
2007-12-18,Weibel Instabilities in Dense Quantum Plasmas,"The quantum effect on the Weibel instability in an unmagnetized plasma is
presented. Our analysis shows that the quantum effect tends to stabilize the
Weibel instability in the hydrodynamic regime, whereas it produces a new
oscillatory instability in the kinetic regime. A novel effect the quantum
damping, which is associated with the Landau damping, is disclosed. The new
quantum Weibel instability may be responsible for the generation of
non-stationary magnetic fields in compact astrophysical objects as well as in
the forthcoming intense laser-solid density plasma experiments.",0712.2874v1
2008-01-18,A qualitative perspective on the dynamics of a single-Cooper-pair box with a phase-damped cavity,"In a recent paper Dajka, et.al., [J. Phys. A \textbf{40}, F879 (2007)]
predicted that some composite systems can be entangled forever even if coupled
with a thermal bath. We analyze the transient entanglement of a
single-Cooper-pair box biased by a classical voltage and irradiated by a
quantized field and find the unusual feature that the phase-damped cavity can
lead to a long-lived entanglement. The results show an asymptotic value of the
idempotency defect (concurrence) which embodies coherence loss (entanglement
survival), independent of the interaction development by dependent critically
on environment.",0801.2905v2
2008-02-28,Current driven spin-wave instability triggered by the anomalous Hall effect,"We studied the effect of strong electric current on spin waves interacting
relativistically with the current. The spin-wave spectrum is calculated at
arbitrary direction of the wave vector. It is shown that the alternating Hall
current generated by the alternating magnetic moment of the spin waves, reduces
the spin-wave damping. At strong enough unpolarized dc current the damping
changes sign, and the spin-wave amplitude starts to increase exponentially fast
with time. The critical current for the spin-wave instability is determined
mainly by the anomalous Hall effect, and can be much smaller than that for the
spin-torque mechanism of instability.",0802.4150v1
2008-03-31,Spectral Modeling of Magnetohydrodynamic Turbulent Flows,"We present a dynamical spectral model for Large Eddy Simulation of the
incompressible magnetohydrodynamic (MHD) equations based on the Eddy Damped
Quasi Normal Markovian approximation. This model extends classical spectral
Large Eddy Simulations for the Navier-Stokes equations to incorporate general
(non Kolmogorovian) spectra as well as eddy noise. We derive the model for MHD
and show that introducing a new eddy-damping time for the dynamics of spectral
tensors in the absence of equipartition between the velocity and magnetic
fields leads to better agreement with direct numerical simulations, an
important point for dynamo computations.",0803.4499v1
2008-04-10,Trapped Phase-Segregated Bose-Fermi Mixtures and their Collective Excitations,"Recent progress in the field of ultracold gases has allowed the creation of
phase-segregated Bose-Fermi systems. We present a theoretical study of their
collective excitations at zero temperature. As the fraction of fermion to boson
particle number increases, the collective mode frequencies take values between
those for a fully bosonic and those for a fully fermionic cloud, with damping
in the intermediate region. This damping is caused by fermions which are
resonantly driven at the interface.",0804.1759v2
2008-04-14,Size dependence of multipolar plasmon resonance frequencies and damping rates in simple metal spherical nanoparticles,"Multipolar plasmon oscillation frequencies and corresponding damping rates
for nanospheres formed of the simplest free-electron metals are studied. The
possibility of controlling plasmon features by choosing the size and dielectric
properties of the sphere surroundings is discussed. Optical properties of the
studied metals are described within the Drude-Sommerfeld model of the
dielectric function with effective parameters acounting for the contribution of
conduction electrons and of interband transitions. No approximation is made in
respect of the size of a particle; plasmon size characteristics are described
rigorously. The results of our experiment on sodium nanodroplets [1] are
compared with the oscillation frequency size dependence of dipole and
quadrupole plasmon.",0804.2156v1
2008-05-09,"Spin dynamics in (III,Mn)V ferromagnetic semiconductors: the role of correlations","We address the role of correlations between spin and charge degrees of
freedom on the dynamical properties of ferromagnetic systems governed by the
magnetic exchange interaction between itinerant and localized spins. For this
we introduce a general theory that treats quantum fluctuations beyond the
Random Phase Approximation based on a correlation expansion of the Green's
function equations of motion. We calculate the spin susceptibility, spin--wave
excitation spectrum, and magnetization precession damping. We find that
correlations strongly affect the magnitude and carrier concentration dependence
of the spin stiffness and magnetization Gilbert damping.",0805.1320v2
2008-06-05,Thermally Assisted Spin Hall Effect,"The spin polarized charge transport is systematically analyzed as a thermally
driven stochastic process. The approach is based on Kramers' equation
describing the semiclassical motion under the inclusion of stochastic and
damping forces. Due to the relativistic spin-orbit coupling the damping
experiences a relativistic correction leading to an additional contribution
within the spin Hall conductivity. A further contribution to the conductivity
is originated from the averaged underlying crystal potential, the mean value of
which depends significantly on the electric field. We derive an exact
expression for the electrical conductivity. All corrections are estimated in
lowest order of a relativistic approach and in the linear response regime.",0806.0948v1
2008-06-13,General Solution of the Quantum Damped Harmonic Oscillator II : Some Examples,"In the preceding paper (arXiv : 0710.2724 [quant-ph]) we have constructed the
general solution for the master equation of quantum damped harmonic oscillator,
which is given by the complicated infinite series in the operator algebra
level. In this paper we give the explicit and compact forms to solutions
(density operators) for some initial values. In particular, the compact one for
the initial value based on a coherent state is given, which has not been given
as far as we know. Moreover, some related problems are presented.",0806.2169v1
2008-08-09,Gilbert Damping in Conducting Ferromagnets I: Kohn-Sham Theory and Atomic-Scale Inhomogeneity,"We derive an approximate expression for the Gilbert damping coefficient
\alpha_G of itinerant electron ferromagnets which is based on their description
in terms of spin-density-functional-theory (SDFT) and Kohn-Sham quasiparticle
orbitals. We argue for an expression in which the coupling of magnetization
fluctuations to particle-hole transitions is weighted by the spin-dependent
part of the theory's exchange-correlation potential, a quantity which has large
spatial variations on an atomic length scale. Our SDFT result for \alpha_G is
closely related to the previously proposed spin-torque correlation-function
expression.",0808.1373v1
2008-08-27,Entanglement dynamics of two-qubit system in different types of noisy channels,"In this paper, we study entanglement dynamics of a two-qubit extended
Werner-like state locally interacting with independent noisy channels, i.e.,
amplitude damping, phase damping and depolarizing channels. We show that the
purity of initial entangled state has direct impacts on the entanglement
robustness in each noisy channel. That is, if the initial entangled state is
prepared in mixed instead of pure form, the state may exhibit entanglement
sudden death (ESD) and/or be decreased for the critical probability at which
the entanglement disappear.",0808.3690v1
2008-09-01,Heatons induced by attosecond laser pulses,"In this paper the dynamics of the interaction of attosecond laser pulses with
matter is investigated. It will be shown that the master equation: modified
Klein-Gordon equation describes the propagation of the heatons. Heatons are the
thermal wave packets. When the duration of the laser pulses is of the order of
attosecond the heaton thermal wave packets are nondispersive objects. For
infinite time the heatons are damped with damping factor of the order of
relaxation time for thermal processes.",0809.0204v1
2008-10-09,Heat conduction in 2D strongly-coupled dusty plasmas,"We perform non-equilibrium simulations to study heat conduction in
two-dimensional strongly coupled dusty plasmas. Temperature gradients are
established by heating one part of the otherwise equilibrium system to a higher
temperature. Heat conductivity is measured directly from the stationary
temperature profile and heat flux. Particular attention is paid to the
influence of damping effect on the heat conduction. It is found that the heat
conductivity increases with the decrease of the damping rate, while its
magnitude agrees with previous experimental measurement.",0810.1623v2
2008-10-21,Structurally damped plate and wave equations with random point force in arbitrary space dimensions,"In this paper we consider structurally damped plate and wave equations with
point and distributed random forces. In order to treat space dimensions more
than one, we work in the setting of $L^q$--spaces with (possibly small)
$q\in(1,2)$. We establish existence, uniqueness and regularity of mild and weak
solutions to the stochastic equations employing recent theory for stochastic
evolution equations in UMD Banach spaces.",0810.3898v2
2008-11-05,Spectral function and quasi-particle damping of interacting bosons in two dimensions,"We employ the functional renormalization group to study dynamical properties
of the two-dimensional Bose gas. Our approach is free of infrared divergences,
which plague the usual diagrammatic approaches, and is consistent with the
exact Nepomnyashchy identity, which states that the anomalous self-energy
vanishes at zero frequency and momentum. We recover the correct infrared
behavior of the propagators and present explicit results for the spectral
line-shape, from which we extract the quasi-particle dispersion and damping.",0811.0624v2
2008-11-13,Existence of weak solutions to the Cauchy problem of a semilinear wave equation with supercritical interior source and damping,"In this paper we show existence of finite energy solutions for the Cauchy
problem associated with a semilinear wave equation with interior damping and
supercritical source terms. The main contribution consists in dealing with
super-supercritical source terms (terms of the order of $|u|^p$ with $p\geq 5$
in $n=3$ dimensions), an open and highly recognized problem in the literature
on nonlinear wave equations.",0811.2151v1
2008-11-17,Asymptotic stability and blow up for a semilinear damped wave equation with dynamic boundary conditions,"In this paper we consider a multi-dimensional wave equation with dynamic
boundary conditions, related to the Kelvin-Voigt damping. Global existence and
asymptotic stability of solutions starting in a stable set are proved. Blow up
for solutions of the problem with linear dynamic boundary conditions with
initial data in the unstable set is also obtained.",0811.2783v3
2008-11-19,Weyl laws for partially open quantum maps,"We study a toy model for ""partially open"" wave-mechanical system, like for
instance a dielectric micro-cavity, in the semiclassical limit where ray
dynamics is applicable. Our model is a quantized map on the 2-dimensional
torus, with an additional damping at each time step, resulting in a subunitary
propagator, or ""damped quantum map"". We obtain analogues of Weyl's laws for
such maps in the semiclassical limit, and draw some more precise estimates when
the classical dynamic is chaotic.",0811.3134v2
2008-12-16,A picogram and nanometer scale photonic crystal opto-mechanical cavity,"We describe the design, fabrication, and measurement of a cavity
opto-mechanical system consisting of two nanobeams of silicon nitride in the
near-field of each other, forming a so-called ""zipper"" cavity. A photonic
crystal patterning is applied to the nanobeams to localize optical and
mechanical energy to the same cubic-micron-scale volume. The picrogram-scale
mass of the structure, along with the strong per-photon optical gradient force,
results in a giant optical spring effect. In addition, a novel damping regime
is explored in which the small heat capacity of the zipper cavity results in
blue-detuned opto-mechanical damping.",0812.2953v1
2009-02-03,Freezing of spin dynamics in underdoped cuprates,"The Mori's memory function approach to spin dynamics in doped
antiferromagnetic insulator combined with the assumption of temperature
independent static spin correlations and constant collective mode damping leads
to w/T scaling in a broad range. The theory involving a nonuniversal scaling
parameter is used to analyze recent inelastic neutron scattering results for
underdoped cuprates. Adopting modified damping function also the emerging
central peak in low-doped cuprates at low temperatures can be explained within
the same framework.",0902.0546v1
2009-02-12,"Discrete breathers in a forced-damped array of coupled pendula: Modeling, Computation and Experiment","In this work, we present a mechanical example of an experimental realization
of a stability reversal between on-site and inter-site centered localized
modes. A corresponding realization of a vanishing of the Peierls-Nabarro
barrier allows for an experimentally observed enhanced mobility of the
localized modes near the reversal point. These features are supported by
detailed numerical computations of the stability and mobility of the discrete
breathers in this system of forced and damped coupled pendula. Furthermore,
additional exotic features of the relevant model, such as dark breathers are
briefly discussed.",0902.2129v1
2009-03-08,Enhancement of transmission rates in quantum memory channels with damping,"We consider the transfer of quantum information down a single-mode quantum
transmission line. Such quantum channel is modeled as a damped harmonic
oscillator, the interaction between the information carriers -a train of N
qubits- and the oscillator being of the Jaynes-Cummings kind. Memory effects
appear if the state of the oscillator is not reset after each channel use. We
show that the setup without resetting is convenient in order to increase the
transmission rates, both for the transfer of quantum and classical private
information. Our results can be applied to the micromaser.",0903.1424v1
2009-03-15,A variational approach to strongly damped wave equations,"We discuss a Hilbert space method that allows to prove analytical
well-posedness of a class of linear strongly damped wave equations. The main
technical tool is a perturbation lemma for sesquilinear forms, which seems to
be new. In most common linear cases we can furthermore apply a recent result
due to Crouzeix--Haase, thus extending several known results and obtaining
optimal analyticity angle.",0903.2599v2
2009-03-30,Damping of Exciton Rabi Rotations by Acoustic Phonons in Optically Excited InGaAs/GaAs Quantum Dots,"We report experimental evidence identifying acoustic phonons as the principal
source of the excitation-induced-dephasing (EID) responsible for the intensity
damping of quantum dot excitonic Rabi rotations. The rate of EID is extracted
from temperature dependent Rabi rotation measurements of the ground-state
excitonic transition, and is found to be in close quantitative agreement with
an acoustic-phonon model.",0903.5278v2
2009-05-13,Landau damping,"In this note we present the main results from the recent work
hal-00376547/arXiv:0904.2760, which for the first time establish Landau damping
in a nonlinear context.",0905.2167v2
2009-05-13,Amortissement Landau,"Dans cette note nous pr\'esentons les principaux r\'esultats du r\'ecent
travail hal-00376547/arXiv:0904.2760, o\`u le ph\'enom\`ene d'amortissement
Landau est pour la premi\`ere fois \'etabli dans un contexte non lin\'eaire.
  -----
  In this note we present the main results from the recent work hal-00376547 /
arXiv:0904.2760, which for the first time establish Landau damping in a
nonlinear context.",0905.2168v2
2009-06-27,Effect of Bohm potential on a charged gas,"Bohm's interpretation of Quantum Mechanics leads to the derivation of a
Quantum Kinetic Equation (QKE): in the present work, propagation of waves in
charged quantum gases is investigated starting from this QKE. Dispersion
relations are derived for fully and weakly degenerate fermions and bosons
(these latter above critical temperature), and the differences underlined. Use
of a kinetic equation permits investigation of ""Landau-type"" damping: it is
found that the presence of damping in fermion gases is dependent upon the
degree of degeneracy, whereas it is always present in boson gases. In fully
degenerate fermions a phenomenon appears that is akin to the ""zero sound""
propagation.",0906.5061v1
2009-07-14,Quantum Monty Hall problem under decoherence,"We study the effect of decoherence on quantum Monty Hall problem under the
influence of amplitude damping, depolarizing and dephasing channels. It is
shown that under the effect of decoherence, there is a Nash equilibrium of the
game in case of depolarizing channel for Alice's quantum strategy. Where as in
case of dephasing noise, the game is not influenced by the quantum channel. For
amplitude damping channel, the Bob's payoffs are found symmetrical with maximum
at p=0.5 against his classical strategy. However, it is worth-mentioning that
in case of depolarizing channel, Bob's classical strategy remains always
dominant against any choice of Alice's strategy.",0907.2293v1
2009-08-31,Rigorous Theory of Optical Trapping by an Optical Vortex Beam,"We propose a rigorous theory for the optical trapping by optical vortices,
which is emerging as an important tool to trap mesoscopic particles. The common
perception is that the trapping is solely due to the gradient force, and may be
characterized by three real force constants. However, we show that the optical
vortex trap can exhibit complex force constants, implying that the trapping
must be stabilized by ambient damping. At different damping levels, particle
shows remarkably different dynamics, such as stable trapping, periodic and
aperiodic orbital motions.",0908.4504v1
2009-09-11,Energy decay for the damped wave equation under a pressure condition,"We establish the presence of a spectral gap near the real axis for the damped
wave equation on a manifold with negative curvature. This results holds under a
dynamical condition expressed by the negativity of a topological pressure with
respect to the geodesic flow. As an application, we show an exponential decay
of the energy for all initial data sufficiently regular. This decay is governed
by the imaginary part of a finite number of eigenvalues close to the real axis.",0909.2093v1
2009-09-12,Signature of smooth transition from diabatic to adiabatic states in heavy-ion fusion reactions at deep subbarrier energies,"We propose a novel extension of the standard coupled-channels framework for
heavy-ion reactions in order to analyze fusion reactions at deep subbarrier
incident energies. This extension simulates a smooth transition between the
diabatic two-body and the adiabatic one-body states. To this end, we damp
gradually the off-diagonal part of the coupling potential, for which the
position of the onset of the damping varies for each eigen channel. We show
that this model accounts well for the steep falloff of the fusion cross
sections for the $^{16}$O+$^{208}$Pb, $^{64}$Ni+$^{64}$Ni, and
$^{58}$Ni+$^{58}$Ni reactions.",0909.2298v1
2009-10-05,Construction of quasi-periodic response solutions in forced strongly dissipative systems,"We consider a class of ordinary differential equations describing
one-dimensional quasiperiodically forced systems in the presence of large
damping. We give a fully constructive proof of the existence of response
solutions, that is quasi-periodic solutions which have the same frequency
vector as the forcing. This requires dealing with a degenerate implicit
function equation: we prove that the latter has a unique solution, which can be
explicitly determined. As a by-product we obtain an explicit estimate of the
minimal size of the damping coefficient.",0910.0746v1
2009-10-14,Plasmon-phonon Strongly-Coupled Mode in Epitaxial Graphene,"We report the dispersion measurements, using angle-resolved reflection
electron-energy-loss-spectroscopy (AREELS), on two-dimensional (2D) plasmons in
single and multilayer graphene which couple strongly to surface optical phonon
(FK phonon) modes of silicon carbide substrate. The coupled modes show discrete
dispersion behaviors in the single and bilayer graphene. With increasing
graphene layers on SiC(0001), a transition from plasmon-like dispersion to
phonon-like dispersion is observed. For plasmon-like modes, the dispersion is
strongly damped by electron-hole pair excitations at entering single-particle
continuum, while phonon-like mode is undamped. In the region free of coupling,
the graphene 2D plasmon exhibits acoustic behavior with linear dispersion with
slope and damping determined by the Fermi surface topology.",0910.2735v1
2009-10-23,Collective Enhancement and Suppression of Excitation Decay in Optical Lattices,"We calculate radiative lifetimes of collective electronic excitations of
atoms in an infinite one dimensional lattice. The translational symmetry along
the lattice restricts the photon wave vector component parallel to the lattice
to the exciton wave number and thus the possible emission directions. The
resulting radiation damping rate and emission pattern of the exciton strongly
deviates from independent atom. For some wave numbers and polarizations the
excitons superradiantly decay very fast, while other excitons show zero
radiation damping rate and form propagating meta-stable excitations. Such
states could be directly coupled via tailored evanescent fields from a nearby
fiber.",0910.4501v1
2009-10-24,Global Attractor for Weakly Damped Forced KdV Equation in Low Regularity on T,"In this paper we consider the long time behavior of the weakly damped, forced
Korteweg-de Vries equation in the Sololev spaces of the negative indices in the
periodic case. We prove that the solutions are uniformly bounded in
$\dot{H}^s(\T)$ for $s>-\dfrac{1}{2}$. Moreover, we show that the solution-map
possesses a global attractor in $\dot{H}^s(\T)$ for $s>-\dfrac{1}{2}$, which is
a compact set in $H^{s+3}(\T)$.",0910.4652v1
2009-10-24,Two bodies gravitational system with variable mass and damping-antidamping effect due to star wind,"We study two-bodies gravitational problem where the mass of one of the bodies
varies and suffers a damping-antidamping effect due to star wind during its
motion. A constant of motion, a Lagrangian and a Hamiltonian are given for the
radial motion of the system, and the period of the body is studied using the
constant of motion of the system. An application to the comet motion is given,
using the comet Halley as an example.",0910.4684v2
2009-11-12,A new perspective on supersymmetric inflation,"We consider supersymmetric inflation with the hybrid-type potential. In the
absence of the symmetry that forbids Hubble-induced mass terms, the inflaton
mass will be as large as the Hubble scale during inflation. We consider
gravitational decay of the trigger field as the least decay mode and find that
the damping caused by the dissipation can dominate the friction of the inflaton
when the heavy trigger field is coupled to the inflaton. The dissipative
damping provides a solution to the traditional $\eta$ problem without
introducing additional symmetry and interactions. Considering the spatial
inhomogeneities of the dissipative coefficient, we find that modulated
inflation (modulation of the inflaton velocity) can create significant
curvature perturbations.",0911.2350v1
2010-01-16,Resonance Damping in Ferromagnets and Ferroelectrics,"The phenomenological equations of motion for the relaxation of ordered phases
of magnetized and polarized crystal phases can be developed in close analogy
with one another. For the case of magnetized systems, the driving magnetic
field intensity toward relaxation was developed by Gilbert. For the case of
polarized systems, the driving electric field intensity toward relaxation was
developed by Khalatnikov. The transport times for relaxation into thermal
equilibrium can be attributed to viscous sound wave damping via
magnetostriction for the magnetic case and electrostriction for the
polarization case.",1001.2845v1
2010-02-05,Damping Effect of Electromagnetic Radiation and Time-Dependent Schrodinger Equation,"The inexactness of the time-dependent Schr\""odinger equation of a charged
particle in an external electromagnetic field is discussed in terms of the
damping effect of the radiation. A possible improvement is to add a nonlinear
term representing this effect to the linear Schr\""odinger equation. Conditions
for the nonlinear term are investigated and it is demonstrated that the
obtained nonlinear Schr\""odinger equation may present state evolutions similar
to the wave-function reduction and transitions between stationary states.",1002.1116v3
2010-02-05,Uniform stabilization in weighted Sobolev spaces for the KdV equation posed on the half-line,"Studied here is the large-time behavior of solutions of the Korteweg-de Vries
equation posed on the right half-line under the effect of a localized damping.
Assuming as in \cite{linares-pazoto} that the damping is active on a set
$(a_0,+\infty)$ with $a_0>0$, we establish the exponential decay of the
solutions in the weighted spaces $L^2((x+1)^mdx)$ for $m\in \N ^*$ and
$L^2(e^{2bx}dx)$ for $b>0$ by a Lyapunov approach. The decay of the spatial
derivatives of the solution is also derived.",1002.1127v1
2010-03-28,Giant magnetic broadening of ferromagnetic resonance in a GMR Co/Ag/Co/Gd quadlayer,"Both magnetic-resonance damping and the giant magnetoresistance effect have
been predicted to be strongly affected by the local density of states in thin
ferromagnetic films. We employ the antiferromagnetic coupling between Co and Gd
to provide a spontaneous change from parallel to antiparallel alignment of two
Co films. A sharp increase in magnetic damping accompanies the change from
parallel to antiparallel alignment, analogous to resistivity changes in giant
magnetoresistance.",1003.5344v1
2010-04-04,Quantum information reclaiming after amplitude damping,"We investigate the quantum information reclaim from the environment after
amplitude damping has occurred. In particular we address the question of
optimal measurement on the environment to perform the best possible correction
on two and three dimensional quantum systems. Depending on the dimension we
show that the entanglement fidelity (the measure quantifying the correction
performance) is or is not the same for all possible measurements and uncover
the optimal measurement leading to the maximum entanglement fidelity.",1004.0497v1
2010-04-09,Validity of Landauer's principle in the quantum regime,"We demonstrate the validity of Landauer's erasure principle in the strong
coupling quantum regime by treating the system-reservoir interaction in a
consistent way. We show that the initial coupling to the reservoir modifies
both energy and entropy of the system and provide explicit expressions for the
latter in the case of a damped quantum harmonic oscillator. These contributions
are related to the Hamiltonian of mean force and dominate in the strong damping
limit. They need therefore to be fully taken into account in any
low-temperature thermodynamic analysis of quantum systems.",1004.1599v1
2010-04-22,Critical exponent for damped wave equations with nonlinear memory,"We consider the Cauchy problem in $\mathbb{R}^n,$ $n\geq 1,$ for a semilinear
damped wave equation with nonlinear memory. Global existence and asymptotic
behavior as $t\rightarrow\infty$ of small data solutions have been established
in the case when $1\leq n\leq3.$ Moreover, we derive a blow-up result under
some positive data in any dimensional space.",1004.3850v4
2010-04-26,Entanglement of a two-particle Gaussian state interacting with a heat bath,"The effect of a thermal reservoir is investigated on a bipartite Gaussian
state. We derive a pre-Lindblad master equation in the non-rotating wave
approximation for the system. We then solve the master equation for a bipartite
harmonic oscillator Hamiltonian with entangled initial state. We show that for
strong damping the loss of entanglement is the same as for freely evolving
particles. However, if the damping is small, the entanglement is shown to
oscillate and eventually tend to a constant nonzero value.",1004.4515v2
2010-06-09,Dispersion and damping of two-dimensional dust acoustic waves: Theory and Simulation,"A two-dimensional generalized hydrodynamics (GH) model is developed to study
the full spectrum of both longitudinal and transverse dust acoustic waves (DAW)
in strongly coupled complex (dusty) plasmas, with memory-function-formalism
being implemented to enforce high-frequency sum rules. Results are compared
with earlier theories (such as quasi-localized charge approximation and its
extended version) and with a self-consistent Brownian dynamics simulation. It
is found that the GH approach provides good account, not only for dispersion
relations, but also for damping rates of the DAW modes in a wide range of
coupling strengths, an issue hitherto not fully addressed for dusty plasmas.",1006.1799v1
2010-07-01,Finite time extinction by nonlinear damping for Schrodinger equation,"We consider the Schrodinger equation on a compact manifold, in the presence
of a nonlinear damping term, which is homogeneous and sublinear. For initial
data in the energy space, we construct a weak solution, defined for all
positive time, which is shown to be unique. In the one-dimensional case, we
show that it becomes zero in finite time. In the two and three-dimensional
cases, we prove the same result under the assumption of extra regularity on the
initial datum.",1007.0077v2
2010-07-07,Spin drag Hall effect in a rotating Bose mixture,"We show that in a rotating two-component Bose mixture, the spin drag between
the two different spin species shows a Hall effect. This spin drag Hall effect
can be observed experimentally by studying the out-of-phase dipole mode of the
mixture. We determine the damping of this mode due to spin drag as a function
of temperature. We find that due to Bose stimulation there is a strong
enhancement of the damping for temperatures close to the critical temperature
for Bose-Einstein condensation.",1007.1088v1
2010-08-30,Synthesis of electrical networks interconnecting PZT actuators to damp mechanical vibrations,"This paper proves that it is possible to damp mechanical vibrations of some
beam frames by means of piezoelectric actuators interconnected via passive
networks. We create a kind of electromechanical wave guide where the electrical
velocity group equals the mechanical one thus enabling an electromechanical
energy transfer. Numerical simulations are presented which prove the technical
feasibility of proposed device",1008.5112v1
2010-09-09,The Damped String Problem Revisited,"We revisit the damped string equation on a compact interval with a variety of
boundary conditions and derive an infinite sequence of trace formulas
associated with it, employing methods familiar from supersymmetric quantum
mechanics. We also derive completeness and Riesz basis results (with
parentheses) for the associated root functions under less smoothness
assumptions on the coefficients than usual, using operator theoretic methods
(rather than detailed eigenvalue and root function asymptotics) only.",1009.1858v1
2010-09-15,Anomalous High-Energy Spin Excitations in La2CuO4,"Inelastic neutron scattering is used to investigate the collective magnetic
excitations of the high-temperature superconductor parent antiferromagnet
La2CuO4. We find that while the lower energy excitations are well described by
spin-wave theory, including one- and two-magnon scattering processes, the
high-energy spin waves are strongly damped near the (1/2,0) position in
reciprocal space and merge into a momentum dependent continuum. This anomalous
damping indicates the decay of spin waves into other excitations, possibly
unbound spinon pairs.",1009.2915v1
2010-10-05,Damping of dHvA oscillations and vortex-lattice disorder in the peak-effect region of strong type-II superconductors,"The phenomenon of magnetic quantum oscillations in the superconducting state
poses several questions that still defy satisfactory answers. A key
controversial issue concerns the additional damping observed in the vortex
state. Here, we show results of \mu SR, dHvA, and SQUID magnetization
measurements on borocarbide superconductors, indicating that a sharp drop
observed in the dHvA amplitude just below H_{c2} is correlated with enhanced
disorder of the vortex lattice in the peak-effect region, which significantly
enhances quasiparticle scattering by the pair potential.",1010.0929v1
2010-10-21,Classical behavior of strongly correlated Fermi systems near a quantum critical point. Transport properties,"The low-temperature kinetics of the strongly correlated electron liquid
inhabiting a solid is analyzed. It is demonstrated that a softly damped branch
of transverse zero sound emerges when several bands cross the Fermi surface
simultaneously near a quantum critical point at which the density of states
diverges. Suppression of the damping of this branch occurs due to a mechanism
analogous to that affecting the phonon mode in solids at room temperature,
giving rise to a classical regime of transport at extremely low temperatures in
the strongly correlated Fermi system.",1010.4547v1
2010-10-26,Open Quantum Systems in Noninertial Frames,"We study the effects of decoherence on the entanglement generated by Unruh
effect in noninertial frames by using bit flip, phase damping and depolarizing
channels. It is shown that decoherence strongly influences the initial state
entanglement. The entanglement sudden death can happens irrespective of the
acceleration of the noninertial frame under the action of phase flip and phase
damping channels. It is investigated that an early sudden death happens for
large acceleration under the depolarizing environment. Moreover, the
entanglement increases for a highly decohered phase flip channel.",1010.5395v1
2010-11-17,Faint Resonantly Scattered Lyman Alpha Emission from the Absorption Troughs of Damped Lyman Alpha Systems at z ~ 3,"We demonstrate that the Lyman alpha emission in the absorption troughs of a
large sample of stacked damped Lyman alpha absorption systems (DLAS) presented
by Rahmani et al (2010) is consistent with the spectral profiles and
luminosities of a recently detected population of faint Lyman alpha emitters at
z ~ 3. This result supports the suggestion that the faint emitters are to be
identified with the host galaxies of DLAS at these redshifts.",1011.4061v1
2010-12-19,Quantum damping of Fermi-Pasta-Ulam revivals in ultracold Bose gases,"We propose an experimental scheme for studying the Fermi-Pasta-Ulam (FPU)
phenomenon in a quantum mechanical regime using ultracold atoms. Specifically,
we suggest and analyze a setup of one-dimensional Bose gases confined into an
optical lattice. The strength of quantum fluctuations is controlled by tuning
the number of atoms per lattice sites (filling factor). By simulating the
real-time dynamics of the Bose-Hubbard model by means of the exact numerical
method of time-evolving block decimation, we investigate the effects of quantum
fluctuations on the FPU recurrence and show that strong quantum fluctuations
cause significant damping of the FPU oscillation.",1012.4159v1
2010-12-21,Pullback attractors for a singularly nonautonomous plate equation,"We consider the family of singularly nonautonomous plate equation with
structural damping \[ u_{tt} + a(t,x)u_{t} + (- \Delta) u_{t} + (-\Delta)^{2} u
+ \lambda u = f(u), \] in a bounded domain $\Omega \subset \R^n$, with Navier
boundary conditions. When the nonlinearity $f$ is dissipative we show that this
problem is globally well posed in $H^2_0(\Omega) \times L^2(\Omega)$ and has a
family of pullback attractors which is upper-semicontinuous under small
perturbations of the damping $a$.",1012.4749v1
2010-12-30,On rotational solutions for elliptically excited pendulum,"The author considers the planar rotational motion of the mathematical
pendulum with its pivot oscillating both vertically and horizontally, so the
trajectory of the pivot is an ellipse close to a circle. The analysis is based
on the exact rotational solutions in the case of circular pivot trajectory and
zero gravity. The conditions for existence and stability of such solutions are
derived. Assuming that the amplitudes of excitations are not small while the
pivot trajectory has small ellipticity the approximate solutions are found both
for high and small linear damping. Comparison between approximate and numerical
solutions is made for different values of the damping parameter.",1101.0062v1
2011-01-28,Entanglement between two atoms in a damping Jaynes-Cummings model,"The entanglement between two atoms in a damping Jaynes-Cummings model is
investigated with different decay coefficients of the atoms from the upper
level to other levels under detuning between the atomic frequency and the
quantized light field frequency. The results indicate that the larger the decay
coefficient is, the more quickly the entanglement decays. The detuning enhances
the entanglement's average value at long times. More importantly, the results
show that the so-called sudden death effect can be avoided by enhancing the
detuning or the decay coefficient.",1101.5522v1
2011-03-10,Laser-like vibrational instability in rectifying molecular conductors,"We study the damping of molecular vibrations due to electron-hole pair
excitations in donor-acceptor(D-A) type molecular rectifiers. At finite voltage
additional non-equilibrium electron-hole pair excitations involving both
electrodes become possible, and contribute to the stimulated emission and
absorption of phonons. We point out a generic mechanism for D-A molecules,
where the stimulated emission can dominate beyond a certain voltage due to
inverted position of the D and A quantum resonances. This leads to
current-driven amplification (negative damping) of the phonons similar to
laser-action. We investigate the effect in realistic molecular rectifier
structures using first principles calculations.",1103.1990v1
2011-03-11,Spin Transport in Polaronic and Superfluid Fermi Gases,"We present measurements of spin transport in ultracold gases of fermionic
lithium-6 in a mixture of two spin states at a Feshbach resonance. In
particular, we study the spin dipole mode, where the two spin components are
displaced from each other against a harmonic restoring force. We prepare a
highly-imbalanced, or polaronic, spin mixture with a spin dipole excitation and
observe strong, unitarity limited damping of the spin dipole mode. In gases
with small spin imbalance, below the Pauli limit for superfluidity, we observe
strongly damped spin flow despite the presence of a superfluid core.",1103.2337v1
2011-03-14,Tidal Evolution of a Secularly Interacting Planetary System,"In a multi-planet system, a gradual change in one planet's semi-major axis
will affect the eccentricities of all the planets, as angular momentum is
distributed via secular interactions. If tidal dissipation in the planet is the
cause of the change in semi-major axis, it also damps that planet's
eccentricity, which in turn also contributes to the evolution of all the
eccentricities. Formulae quantifying the combined effects on the whole system
due to semi-major axis changes, as well as eccentricity damping, are derived
here for a two-planet system. The CoRoT 7 system is considered as an example.",1103.2794v1
2011-03-30,Damping in quantum love affairs,"In a series of recent papers we have used an operatorial technique to
describe stock markets and, in a different context, {\em love affairs} and
their time evolutions. The strategy proposed so far does not allow any dumping
effect. In this short note we show how, within the same framework, a strictly
non periodic or quasi-periodic effect can be introduced in the model by
describing in some details a linear Alice-Bob love relation with damping.",1103.5907v1
2011-04-03,Spatially confined Bloch oscillations in semiconductor superlattices,"In a semiconductor superlattice with long scattering times, damping of Bloch
oscillations due to scattering is so small that convective nonlinearities may
compensate it and Bloch oscillations persist even in the hydrodynamic regime.
In this case, numerical solutions show that there are stable Bloch oscillations
confined to a region near the collector with inhomogeneous field, charge,
current density and energy density profiles. These Bloch oscillations disappear
when damping due to inelastic collisions becomes sufficiently strong.",1104.0429v2
2011-04-06,Relativistic magnetic reconnection at X-type neutral points,"Relativistic effects in the oscillatory damping of magnetic disturbances near
two-dimensional X-points are investigated. By taking into account displacement
current, we study new features of extremely magnetized systems, in which the
Alfv\'en velocity is almost the speed of light. The frequencies of the
least-damped mode are calculated using linearized relativistic MHD equations
for wide ranges of the Lundquist number S and the magnetization parameter
$\sigma$. These timescales approach constant values in the large resistive
limit: the oscillation time becomes a few times the light crossing time,
irrespective of $\sigma$, and the decay time is proportional to $\sigma$ and
therefore is longer for a highly magnetized system.",1104.1003v1
2011-04-06,Observed damping of the slow magnetoacoustic mode,"Spectroscopic and stereoscopic imaging observations of slow magnetoacoustic
wave propagation within a coronal loop are investigated to determine the decay
length scale of the slow magnetoacoustic mode in three dimensions and the
density profile within the loop system. The slow wave is found to have an
e-folding decay length scale of $20,000^{+4000}_{-3000}$km with a uniform
density profile along the loop base. These observations place quantitive
constraints on the modelling of wave propagation within coronal loops.
Theoretical forward modelling suggests that magnetic field line divergence is
the dominant damping factor and thermal conduction is insufficient, given the
observed parameters of the coronal loop temperature, density and wave mode
period.",1104.1100v1
2011-04-17,Stochastic Wave Equations with Nonlinear Damping and Source Terms,"In this paper, we discuss an initial boundary value problem for the
stochastic wave equation involving the nonlinear damping term $|u_t|^{q-2}u_t$
and a source term of the type $|u|^{p-2}u$. We firstly establish the local
existence and uniqueness of solution by the Galerkin approximation method and
show that the solution is global for $q\geq p$. Secondly, by an appropriate
energy inequality, the local solution of the stochastic equations will blow up
with positive probability or explosive in energy sense for $p>q$.",1104.3279v2
2011-05-07,Cooperative scattering measurement of coherence in a spatially modulated Bose gas,"Correlations of a Bose gas released from an optical lattice are measured
using superradiant scattering. Conditions are chosen so that after initial
incident light pumping at the Bragg angle for diffraction, due to matter wave
amplification and mode competition, superradiant scattering into the Bragg
diffracted mode is preponderant. A temporal analysis of the superradiant
scattering gain reveals periodical oscillations and damping due to the initial
lack of coherence between lattice sites. Such damping is used for
characterizing first order spatial correlations in our system with a precision
of one lattice period.",1105.1425v1
2011-06-09,Hamiltonian of mean force for damped quantum systems,"We consider a quantum system linearly coupled to a reservoir of harmonic
oscillators. For finite coupling strengths, the stationary distribution of the
damped system is not of the Gibbs form, in contrast to standard thermodynamics.
With the help of the quantum Hamiltonian of mean force, we quantify this
deviation exactly for a harmonic oscillator and provide approximations in the
limit of high and low temperatures, and weak and strong couplings. Moreover, in
the semiclassical regime, we use the quantum Smoluchowski equation to obtain
results valid for any potential. We, finally, give a physical interpretation of
the deviation in terms of the initial system-reservoir coupling.",1106.1775v1
2011-06-17,Current effect on magnetization oscillations in a ferromagnet - antiferromagnet junction,"Spin-polarized current effect is studied on the static and dynamic
magnetization of the antiferromagnet in a ferromagnet - antiferromagnet
junction. The macrospin approximation is generalized to antiferromagnets.
Canted antiferromagnetic configuration and resulting magnetic moment are
induced by an external magnetic field. The resonance frequency and damping are
calculated, as well as the threshold current density corresponding to
instability appearance. A possibility is shown of generating low-damping
magnetization oscillations in terahertz range. The fluctuation effect is
discussed on the canted antiferromagnetic configuration.",1106.3519v1
2011-06-23,Dissipation evidence for the quantum damped harmonic oscillator via pseudo-bosons,"It is known that a self-adjoint, time-independent hamiltonian can be defined
for the quantum damped harmonic oscillator. We show here that the two vacua
naturally associated to this operator, when expressed in terms of
pseudo-bosonic lowering and raising operators, appear to be non
square-integrable. This fact is interpreted as the evidence of the dissipation
effect of the classical oscillator at a purely quantum level.",1106.4638v1
2011-08-08,"Synchrotron radiation damping, intrabeam scattering and beam-beam simulations for HE-LHC","The proposed High-Energy LHC project presents an unusual combination of
strong synchrotron radiation (SR) damping and intrabeam scattering (IBS), which
is not seen in present-day hadron colliders. The subject of investigation
reported in this paper was the simulation of beam-beam effect for the HE-LHC
parameters. Parameters of SR and IBS are calculated, and the luminosity
evolution is simulated in the absence of beambeam interaction. Then, a
weak-strong numerical simulation is used to predict the effect of beam-beam
interaction on particle losses and emittance evolution.",1108.1644v1
2011-09-08,On the attenuation coefficient of monomode periodic waveguides,"It is widely accepted that, on ensemble average, the transmission T of guided
modes decays exponentially with the waveguide length L due to small
imperfections, leading to the important figure of merit defined as the
attenuation-rate coefficient alpha = -<ln(T)>/L. In this letter, we evidence
that the exponential-damping law is not valid in general for periodic monomode
waveguides, especially as the group velocity decreases. This result that
contradicts common beliefs and experimental practices aiming at measuring alpha
is supported by a theoretical study of light transport in the limit of very
small imperfections, and by numerical results obtained for two waveguide
geometries that offer contrasted damping behaviours.",1109.1642v1
2011-09-09,Delocalization of slowly damped eigenmodes on Anosov manifolds,"We look at the properties of high frequency eigenmodes for the damped wave
equation on a compact manifold with an Anosov geodesic flow. We study
eigenmodes with spectral parameters which are asymptotically close enough to
the real axis. We prove that such modes cannot be completely localized on
subsets satisfying a condition of negative topological pressure. As an
application, one can deduce the existence of a ""strip"" of logarithmic size
without eigenvalues below the real axis under this dynamical assumption on the
set of undamped trajectories.",1109.1909v2
2011-10-18,Life times and chirality of spin-waves in antiferromagnetic and ferromagnetic FeRh: time depedent density functional theory perspective,"The study of the spin excitations in antiferromagnetic (AFM) and
ferromagnetic (FM) phases of FeRh is reported. We demonstrate that although the
Fe atomic moments are well defined there is a number of important phenomena
absent in the Heisenberg description: Landau damping of spin waves, large Rh
moments induced by the AFM magnons, the formation of the optical magnons
terminated by Stoner excitations. We relate the properties of the spin-wave
damping to the features of the Stoner continuum and compare the chirality of
the spin excitations in AFM, FM and paramagnetic (PM) systems.",1110.3913v1
2011-10-21,Environment-Assisted Error Correction of Single-Qubit Phase Damping,"Open quantum system dynamics of random unitary type may in principle be fully
undone. Closely following the scheme of environment-assisted error correction
proposed by Gregoratti and Werner [M. Gregoratti and R. F. Werner, J. Mod. Opt.
50(6), 915-933 (2003)], we explicitly carry out all steps needed to invert a
phase-damping error on a single qubit. Furthermore, we extend the scheme to a
mixed-state environment. Surprisingly, we find cases for which the uncorrected
state is closer to the desired state than any of the corrected ones.",1110.4806v1
2011-12-13,Drastically suppressing the error of ballistic readout of qubits,"The thermal jitter of transmission of magnetic flux quanta in long Josephson
junctions is studied. While for large-to-critical damping and small values of
bias current the physically obvious dependence of the jitter versus length
$\sigma\sim\sqrt{L}$ is confirmed, for small damping starting from the
experimentally relevant $\alpha=0.03$ and below strong deviation from
$\sigma\sim\sqrt{L}$ is observed, up to nearly complete independence of the
jitter versus length, which is exciting from fundamental point of view, but
also intriguing from the point of view of possible applications.",1112.2805v1
2011-12-15,Diffusion-Induced Oscillations of Extended Defects,"From a simple model for the driven motion of a planar interface under the
influence of a diffusion field we derive a damped nonlinear oscillator equation
for the interface position. Inside an unstable regime, where the damping term
is negative, we find limit-cycle solutions, describing an oscillatory
propagation of the interface. In case of a growing solidification front this
offers a transparent scenario for the formation of solute bands in binary
alloys, and, taking into account the Mullins-Sekerka instability, of banded
structures.",1112.3669v1
2012-02-18,Dynamics of multi-modes maximum entangled coherent state over amplitude damping channel,"The dynamics of maximum entangled coherent state travels through an amplitude
damping channel is investigated. For small values of the transmissivity rate
the travelling state is very fragile to this noise channel, where it suffers
from the phase flip error with high probability. The entanglement decays
smoothly for larger values of the transmissivity rate and speedily for smaller
values of this rate. As the number of modes increases, the travelling state
over this noise channel loses its entanglement hastily. The odd and even states
vanish at the same value of the field intensity.",1202.4089v1
2012-03-02,Damping-Antidamping Effect on Comets Motion,"We make an observation about Galilean transformation on a 1-D mass variable
systems which leads us to the right way to deal with mass variable systems.
Then using this observation, we study two-bodies gravitational problem where
the mass of one of the bodies varies and suffers a damping-antidamping effect
due to star wind during its motion. For this system, a constant of motion, a
Lagrangian and a Hamiltonian are given for the radial motion, and the period of
the body is studied using the constant of motion of the system. Our theoretical
results are applied to Halley's comet.",1203.0495v2
2012-03-03,Scaling of intrinsic Gilbert damping with spin-orbital coupling strength,"We have experimentally and theoretically investigated the dependence of the
intrinsic Gilbert damping parameter $\alpha_0$ on the spin-orbital coupling
strength $\xi$ by using L1$_{\mathrm{0}}$ ordered
FePd$_{\mathrm{1-x}}$Pt$_{\mathrm{x}}$ ternary alloy films with perpendicular
magnetic anisotropy. With the time-resolved magneto-optical Kerr effect,
$\alpha_0$ is found to increase by more than a factor of ten when $x$ varies
from 0 to 1.0. Since changes of other leading parameters are found to be
neglected, the $\alpha_0$ has for the first time been proven to be proportional
to $\xi^2$.",1203.0607v1
2012-03-03,Necessary and sufficient conditions of freezing phenomena of quantum discord under phase damping,"We investigate the freezing phenomenon of quantum discord occurring in phase
damping noise processes. By relating the expression of the time variation of
the discord to the convex function of relative entropy, we obtain the necessary
and sufficient conditions of the phenomenon for standard Bell-diagonal states.
These conditions are applicable also to the phenomenon occurring in a
non-Markovian dephasing process. Moreover, we show that the same condition and
phenomenon coincide in a new sort of Bell-diagonal states beyond the standard
form.",1203.0650v3
2012-03-06,Universal anomalous diffusion of weakly damped particles,"We show that anomalous diffusion arises in two different models for the
motion of randomly forced and weakly damped particles: one is a generalisation
of the Ornstein-Uhlenbeck process with a random force which depends on position
as well as time, the other is a generalisation of the Chandrasekhar-Rosenbluth
model of stellar dynamics, encompassing non-Coulombic potentials. We show that
both models exhibit anomalous diffusion of position $x$ and momentum $p$ with
the same exponents: $<x^2> \sim C_x t^2$ and $<p^2> \sim C_p t^{2/5}$. We are
able to determine the prefactors $C_x$, $C_p$ analytically.",1203.1354v1
2012-03-09,Collective Light Emission of a Finite Size Atomic Chain,"Radiative properties of collective electronic states in a one dimensional
atomic chain are investigated. Radiative corrections are included with
emphasize put on the effect of the chain size through the dependence on both
the number of atoms and the lattice constant. The damping rates of collective
states are calculated in considering radiative effects for different values of
the lattice constant relative to the atomic transition wave length. Especially
the symmetric state damping rate as a function of the number of the atoms is
derived. The emission pattern off a finite linear chain is also presented. The
results can be adopted for any chain of active material, e.g., a chain of
semiconductor quantum dots or organic molecules on a linear matrix.",1203.2094v1
2012-03-13,Monopoles in ferromagnetic metals,"The aim of this short review is to give an introduction to monopoles and to
present theoretical derivation of two particular monopoles in ferromagnetic
metals, a hedgehog monopole and a spin damping monopole. Spin damping monopoles
can be generated in simple systems such as a junction of a ferromagnet and a
heavy element with strong spin-orbit interaction such as Pt. This monopole is
essential in coupling electronics with magnetism, and is thus expected to play
an essential role in spintronics.",1203.2709v1
2012-03-16,Report from KEK (High gradient study results from Nextef),"Most up-to-date high gradient test of the CLIC prototype structures as of
September 2011 is described in this report. The ""T24"" undamped structure showed
fast processing time, still-decreasing breakdown rate and its breakdown rate
was estimated to be as low as the CLIC requirement. The ""TD24"" damped structure
showed not so excellent high gradient performance as undamped ""T24"" but the
characteristics was much improved than the damped ""TD18"" structure with higher
magnetic field. Further R&D is needed and we present some of the present
efforts at KEK.",1203.3626v1
2012-03-30,Energy decay rates for solutions of the wave equation with linear damping in exterior domain,"In this paper we study the behavior of the energy of solutions of the wave
equation with localized damping in exterior domain. We assume that the damper
is positive at infinity. Under the Geometric Control Condition of Bardos et al
(1992), we prove that: 1) The total energy decay like O(1/t) and L^2-norm is
bounded for the solutions with initial data in (H_{0}^{1},L^{2}). 2) The total
energy and the square of the L^2-norm, repectively, decay like O(1/t^{2}) and
O(1/t) for a kind of the weighted initial data.",1203.6780v4
2012-06-11,Damping and decoherence of Fock states in a nanomechanical resonator due to two level systems,"We numerically investigate the decay of initial quantum Fock states and their
superpositions for a mechanical resonator mode coupled to an environment
comprising interacting, damped tunneling two level system (TLS) defects. The
cases of one, three, and six near resonant, interacting TLS's are considered in
turn and it is found that the resonator displays Ohmic bath like decay behavior
with as few as three TLS's.",1206.2200v1
2012-07-13,Magnetic relaxation in bilayers of yttrium iron garnet/platinum due to the dynamic coupling at the interface,"We show that in ferromagnetic (FM)/normal metal (NM) bilayers the dynamic
coupling at the interface transfers an additional magnetic relaxation from the
heavily damped motion of the conduction electron spins in the NM layer to the
FM spins. While the FM relaxation rates due to two-magnon scattering and spin
pumping decrease rapidly with increasing FM film thickness, the damping due to
the dynamic coupling does not depend on the FM film thickness. The proposed
mechanism explains the very large broadening of ferromagnetic resonance lines
in thick films of yttrium iron garnet after deposition of a Pt layer.",1207.3330v1
2012-07-23,Quantum interference induced by initial system-environment correlations,"We investigate the quantum interference induced by a relative phase in the
correlated initial state of a system which consists in a two-level atom
interacting with a damped mode of the radiation field. We show that the initial
relative phase has significant effects on both the evolution of the atomic
excited-state population and the information flow between the atom and the
reservoir, as quantified by the trace distance. Furthermore, by considering two
two-level atoms interacting with a common damped mode of the radiation field,
we highlight how initial relative phases can affect the subsequent entanglement
dynamics.",1207.5474v1
2012-07-31,An analytic description of the damping of gravitational waves by free streaming neutrinos,"We provide an analytic solution to the general wavelength
integro-differential equation describing the damping of tensor modes of
gravitational waves due to free streaming neutrinos in the early universe. Our
result is expressed as a series of spherical Bessel functions whose
coefficients are functions of the reduced wave number $Q$.",1207.7285v4
2012-08-21,Dancing bunches as Van Kampen modes,"Van Kampen modes are eigen-modes of Jeans-Vlasov equation. Their spectrum
consists of continuous and, possibly, discrete parts. Onset of a discrete van
Kampen mode means emergence of a coherent mode without any Landau damping;
thus, even a tiny couple-bunch wake is sufficient to drive instability.
Longitudinal instabilities observed at Tevatron, RHIC and SPS can be explained
as loss of Landau damping (LLD), which is shown here to happen at fairly low
impedances. For repulsive wakes and single-harmonic RF, LLD is found to be
extremely sensitive to steepness of the bunch distribution function at small
amplitudes. Based on that, a method of beam stabilization is suggested.",1208.4338v1
2012-08-22,Polynomial stabilization of some dissipative hyperbolic systems,"We study the problem of stabilization for the acoustic system with a
spatially distributed damping. Imposing various hypotheses on the structural
properties of the damping term, we identify either exponential or polynomial
decay of solutions with growing time. Expo- nential decay rate is shown by
means of a time domain approach, reducing the problem to an observability
inequality to be verified for solutions of the associated conservative problem.
In addition, we show a polynomial stabilization result, where the proof uses a
frequency domain method and combines a contradiction argument with the
multiplier technique to carry out a special analysis for the resolvent.",1208.4485v1
2012-09-07,Quantum Damped Harmonic Oscillator,"In this chapter we treat the quantum damped harmonic oscillator, and study
mathematical structure of the model, and construct general solution with any
initial condition, and give a quantum counterpart in the case of taking
coherent state as an initial condition.
  This is a simple and good model of Quantum Mechanics with dissipation which
is important to understand real world, and readers will get a powerful weapon
for Quantum Physics.",1209.1437v1
2012-10-08,"Comment on ""Thermal fluctuations of magnetic nanoparticles"" [arXiv:1209.0298]","We comment on some misleading and biased statements appearing in the
manuscript arXiv:1209.0298 (""Thermal fluctuations of magnetic nanoparticles"")
about the use of the damped Landau-Lifshitz equation and the kinetic Langer
theory for the calculation of the relaxation rate of magnetic nanoclusters. We
reiterate simple scientific arguments, part of which is well known to the whole
community, demonstrating that the authors' criticisms are unfounded and that
they overstate the issue of damping in the Landau-Lifshitz equation with no
unanimous experimental evidence.",1210.2436v1
2012-10-10,Phonon momentum and damping of mechanical resonators,"The concept of physical momentum associated to phonons in a crystal,
complemented with some fundamental reasoning, implies measurable effects in
crystals even at a macroscopic scale. We show that, in close analogy with the
transfer of momentum in the kinetic theory of gases, physical momentum carried
by of phonons couples the thermal and the velocity field in a vibrating
crystal. Therefore an heat flow applied to a vibrating crystal can sustain or
damp the oscillation, depending on the interplay between the temperature and
the velocity gradient. We derive the general equations of this effect and show
that its experimental confirmation is within reach of current technology.",1210.2847v1
2012-10-12,HTS wiggler concept for a damping ring,"Magnetic design proposed for a damping ring (DR) is based on second
generation HTS cabling technology applied to the DC windings with a yoke and
mu-metal-shimmed pole to achieve ~2T high-quality field within a 86 mm gap and
32-40 cm period. Low levels of current densities (~90-100A/mm2) provide a
robust, reliable operation of the wiggler at higher heat loads, up to LN2
temperatures with long leads, enhanced flexibility for the cryostats and
infrastructure in harsh radiation environment, and reduced failure rate
compared to the baseline SC ILC DR wiggler design at very competitive cost.",1210.3648v1
2012-10-23,Dynamic response of open cell dry foams,"We study the mechanical response of an open cell dry foam subjected to
periodic forcing using experiments and theory. Using the measurements of the
static and dynamic stress-strain relationship, we derive an over-damped model
of the foam, as a set of infinitesimal non-linear springs, where the damping
term depends on the local foam strain. We then analyse the properties of the
foam when subjected to large amplitudes periodic stresses and determine the
conditions for which the foam becomes optimally absorbing.",1210.6229v1
2012-10-31,Quantum discord of Bell cat-states under amplitude damping,"The evolution of pairwise quantum correlations of Bell cat-states under
amplitude damping is examined using the concept of quantum discord which goes
beyond entanglement. A closed expression of the quantum discord is explicitly
derived. We used of the Koashi-Winter relation. A relation which facilitates
the optimization process of the conditional entropy. We also discuss the
temporal evolution of bipartite quantum correlations under a dephasing channel
and compare the behaviors of quantum discord and entanglement whose properties
are characterized through the concurrence.",1210.8309v1
2012-10-31,Upsilon suppression in PbPb collisions at the LHC,"We suggest that the combined effect of screening, gluon-induced dissociation,
collisional damping, and reduced feed-down explains most of the sequential
suppression of Upsilon(nS) states that has been observed in PbPb relative to pp
collisions at sqrt(s_NN) = 2.76 TeV. The suppression is thus a clear, albeit
indirect, indication for the presence of a QGP. The Upsilon(1S) ground state
suppression is essentially due to reduced feed-down, collisional damping and
gluodissociation, whereas screening prevails for the suppression of the excited
states.",1210.8366v2
2012-11-04,The Threshold between Effective and Noneffective Damping for Semilinear Waves,"In this paper we study the global existence of small data solutions to the
Cauchy problem for the semilinear wave equation with scale-invariant damping.
We obtain estimates for the solution and its energy with the same decay rate of
the linear problem. We extend our results to a model with polynomial speed of
propagation and to a model with an exponential speed of propagation.",1211.0731v2
2012-11-10,Heavy quark quenching from RHIC to LHC and the consequences of gluon damping,"In this contribution to the Quark Matter 2012 conference, we study whether
energy loss models established for RHIC energies to describe the quenching of
heavy quarks can be applied at LHC with the same success. We also benefit from
the larger $p_T$-range accessible at this accelerator to test the impact of
gluon damping on observables such as the nuclear modification factor.",1211.2281v1
2012-11-13,Critical exponent for the semilinear wave equation with scale invariant damping,"In this paper we consider the critical exponent problem for the semilinear
damped wave equation with time-dependent coefficients. We treat the scale
invariant cases. In this case the asymptotic behavior of the solution is very
delicate and the size of coefficient plays an essential role. We shall prove
that if the power of the nonlinearity is greater than the Fujita exponent, then
there exists a unique global solution with small data, provided that the size
of the coefficient is sufficiently large. We shall also prove some blow-up
results even in the case that the coefficient is sufficiently small.",1211.2900v1
2012-11-30,Local feedback stabilisation to a non-stationary solution for a damped non-linear wave equation,"We study a damped semi-linear wave equation in a bounded domain with smooth
boundary. It is proved that any sufficiently smooth solution can be stabilised
locally by a finite-dimensional feedback control supported by a given open
subset satisfying a geometric condition. The proof is based on an investigation
of the linearised equation, for which we construct a stabilising control
satisfying the required properties. We next prove that the same control
stabilises locally the non-linear problem.",1211.7202v1
2012-12-06,The physics of business cycles and inflation,"We analyse four consecutive cycles observed in the USA for employment and
inflation. They are driven by three oil price shocks and an intended interest
rate shock. Non-linear coupling between the rate equations for consumer
products as prey and consumers as predators provides the required instability,
but its natural damping is too high for spontaneous cycles. Extending the
Lotka-Volterra equations with a small term for collective anticipation yields a
second analytic solution without damping. It predicts the base period, phase
shifts, and the sensitivity to shocks for all six cyclic variables correctly.",1212.1282v1
2012-12-13,CMB Distortions from Damping of Acoustic Waves Produced by Cosmic Strings,"We study diffusion damping of acoustic waves in the photon-baryon fluid due
to cosmic strings, and calculate the induced $\mu$- and $y$-type spectral
distortions of the cosmic microwave background. For cosmic strings with tension
within current bounds, their contribution to the spectral distortions is
subdominant compared to the distortions from primordial density perturbations.",1212.3283v2
2013-01-21,Asymptotic parabolicity for strongly damped wave equations,"For $S$ a positive selfadjoint operator on a Hilbert space, \[
\frac{d^2u}{dt}(t) + 2 F(S)\frac{du}{dt}(t) + S^2u(t)=0 \] describes a class of
wave equations with strong friction or damping if $F$ is a positive Borel
function. Under suitable hypotheses, it is shown that \[ u(t)=v(t)+ w(t) \]
where $v$ satisfies \[ 2F(S)\frac{dv}{dt}(t)+ S^2v(t)=0 \] and \[
\frac{w(t)}{\|v(t)\|} \rightarrow 0, \; \text{as} \; t \rightarrow +\infty. \]
The required initial condition $v(0)$ is given in a canonical way in terms of
$u(0)$, $u'(0)$.",1301.4979v1
2013-02-04,Gravity waves on the surface of topological superfluid 3He-B,"We have observed waves on the free surface of 3He-B sample at temperatures
below 0.2mK. The waves are excited by vibrations of the cryostat and detected
by coupling the surface to the Bose-Einstein condensate of magnon
quasiparticles in the superfluid. The two lowest gravity-wave modes in our
cylindrical container are identified. Damping of the waves increases with
temperature linearly with the density of thermal quasiparticles, as expected.
Additionally finite damping of the waves in the zero-temperature limit and
enhancement of magnetic relaxation of magnon condensates by the surface waves
are observed. We discuss whether the latter effects may be related to Majorana
fermions bound to the surface of the topological superfluid.",1302.0764v1
2013-02-12,On the fractional damped oscillators and fractional forced oscillators,"In this paper, we use the fractional calculus to discuss the fractional
mechanics, where the time derivative is replaced with the fractional derivative
of order $\nu$. We deal with the motion of a body in a resisting medium where
the retarding force is assumed to be proportional to the fractional velocity
which is obtained by acting the fractional derivative on the position. The
fractional harmonic oscillator problem, fractional damped oscillator problem
and fractional forced oscillator problem are also studied.",1302.2847v1
2013-02-25,Optimal damping algorithm for unrestricted Hartree-Fock calculations,"We have developed a couple of optimal damping algorithms (ODAs) for
unrestricted Hartree-Fock (UHF) calculations of open-shell molecular systems. A
series of equations were derived for both concurrent and alternate
constructions of alpha- and beta-Fock matrices in the integral-direct
self-consistent-field (SCF) procedure. Several test calculations were performed
to check the convergence behaviors. It was shown that the concurrent algorithm
provides better performance than does the alternate one.",1302.6099v1
2013-03-08,Entanglement of Open Quantum Systems in Noninertial Frames,"We study the effects of decoherence on the entanglement generated by Unruh
effect in accelerated frames by using various combinations of an amplitude
damping channel, a phase damping channel and a depolarizing channel in the form
of multilocal and collective environments. Using concurrence as entanglement
quantifier, we show that the occurrence of entanglement sudden death (ESD)
depends on different combinations of the channels. The ESD can be avoided under
a particular configuration of the channels. We show that the channels can be
used to distinguish between a moving and a stationary frame.",1303.2034v1
2013-03-20,Spin-pumping and Enhanced Gilbert Damping in Thin Magnetic Insulator Films,"Precessing magnetization in a thin film magnetic insulator pumps spins into
adjacent metals; however, this phenomenon is not quantitatively understood. We
present a theory for the dependence of spin-pumping on the transverse mode
number and in-plane wave vector. For long-wavelength spin waves, the enhanced
Gilbert damping for the transverse mode volume waves is twice that of the
macrospin mode, and for surface modes, the enhancement can be ten or more times
stronger. Spin-pumping is negligible for short-wavelength exchange spin waves.
We corroborate our analytical theory with numerical calculations in agreement
with recent experimental results.",1303.4922v1
2013-03-21,Glued trees algorithm under phase damping,"We study the behaviour of the glued trees algorithm described by Childs et
al. in [STOC `03, Proc. 35th ACM Symposium on Theory of Computing (2004) 59]
under decoherence. We consider a discrete time reformulation of the continuous
time quantum walk protocol and apply a phase damping channel to the coin state,
investigating the effect of such a mechanism on the probability of the walker
appearing on the target vertex of the graph. We pay particular attention to any
potential advantage coming from the use of weak decoherence for the spreading
of the walk across the glued trees graph.",1303.5319v2
2013-04-04,Pais-Uhlenbeck Oscillator with a Benign Friction Force,"It is shown that the Pais-Uhlenbeck oscillator with damping, considered by
Nesterenko, is a special case of a more general oscillator that has not only a
first order, but also a third order friction term. If the corresponding damping
constants, \alpha\ and \beta, are both positive and below certain critical
values, then the system is stable. In particular, if \alpha = - \beta, then we
have the unstable Nesterenko's oscillator",1304.1325v2
2013-05-13,Guaranteed convergence of the Kohn-Sham equations,"A sufficiently damped iteration of the Kohn-Sham equations with the exact
functional is proven to always converge to the true ground-state density,
regardless of the initial density or the strength of electron correlation, for
finite Coulomb systems. We numerically implement the exact functional for
one-dimensional continuum systems and demonstrate convergence of the damped KS
algorithm. More strongly correlated systems converge more slowly.",1305.2967v2
2013-06-25,Decoherence effects in the quantum qubit flip game using Markovian approximation,"We are considering a quantum version of the penny flip game, whose
implementation is influenced by the environment that causes decoherence of the
system. In order to model the decoherence we assume Markovian approximation of
open quantum system dynamics. We focus our attention on the phase damping,
amplitude damping and amplitude raising channels. Our results show that the
Pauli strategy is no longer a Nash equilibrium under decoherence. We attempt to
optimize the players' control pulses in the aforementioned setup to allow them
to achieve higher probability of winning the game compared to the Pauli
strategy.",1306.5957v1
2013-07-06,The 3-dimensional oscillon equation,"On a bounded three-dimensional smooth domain, we consider the generalized
oscillon equation with Dirichlet boundary conditions, with time-dependent
damping and time-dependent squared speed of propagation. Under structural
assumptions on the damping and the speed of propagation, which include the
relevant physical case of reheating phase of inflation, we establish the
existence of a pullback global attractor of optimal regularity, and
finite-dimensionality of the kernel sections.",1307.1777v1
2013-07-17,Functional inequalities on path space over a non-compact Riemannian manifold,"We prove the existence of the O-U Dirichlet form and the damped O-U Dirichlet
form on path space over a general non-compact Riemannian manifold which is
complete and stochastically complete. We show a weighted log-Sobolev inequality
for the O-U Dirichlet form and the (standard) log-Sobolev inequality for the
damped O-U Dirichlet form. In particular, the Poincar\'e inequality (and the
super Poincar\'e inequality) can be established for the O-U Dirichlet form on
path space over a class of Riemannian manifolds with unbounded Ricci
curvatures. Moreover, we construct a large class of quasi-regular local
Dirichlet forms with unbounded random diffusion coefficients on the path space
over a general non-compact manifold.",1307.4482v2
2013-10-01,Scalar filed evolution and area spectrum for Lovelock-AdS black holes,"We study the modes of evolution of massless scalar fields in the
asymptotically AdS spacetime surrounding maximally symmetric black holes of
large and intermediate size in the Lovelock model. It is observed that all
modes are purely damped at higher orders. Also, the rate of damping is seen to
be independent of order at higher dimensions. The asymptotic form of these
frequencies for the case of large black holes is found analytically. Finally,
the area spectrum for such black holes is found from these asymptotic modes.",1310.0159v2
2013-10-16,Perturbative quantum damping of cosmological expansion,"Perturbative quantum gravity in the framework of the Schwinger-Keldysh
formalism is applied to compute lowest-order corrections to the actual
expansion of the Universe described in terms of the spatially flat
Friedman-Lematre-Robertson-Walker solution. The classical metric is
approximated by a third order polynomial perturbation around the Minkowski
metric. It is shown that the quantum contribution to the classical expansion,
although extremely small, has damping properties (quantum friction), i.e. it
slows down the expansion.",1310.4308v2
2013-10-27,Loss of non-Gaussianity for damped photon-subtracted thermal states,"We investigate non-Gaussianity properties for a set of classical one-mode
states obtained by subtracting photons from a thermal state. Three
distance-type degrees of non-Gaussianity used for these states are shown to
have a monotonic behaviour with respect to their mean photon number. Decaying
of their non-Gaussianity under damping is found to be consistently described by
the distance-type measures considered here. We also compare the dissipative
evolution of non-Gaussianity when starting from $M$-photon-subtracted and
$M$-photon-added thermal states",1310.7229v1
2013-10-27,Landau damping effects and evolutions of energy spread in small isochronous ring,"This paper presents the Landau damping effects on the microwave instability
of a coasting long bunch in an isochronous ring due to finite energy spread and
emittance. Our two-dimensional (2D) dispersion relation gives more accurate
predictions of the microwave instability growth rates of short-wavelength
perturbations than the conventional 1D formula. The long-term evolution of
energy spread is also studied by measurements and simulations.",1310.7253v3
2013-10-28,Robustness of multiparticle entanglement: specific entanglement classes and random states,"We investigate the robustness of genuine multiparticle entanglement under
decoherence. We consider different kinds of entangled three- and four-qubit
states as well as random pure states. For amplitude damping noise, we find that
the W-type states are most robust, while other states are not more robust than
generic states. For phase damping noise the GHZ state is the most robust state,
and for depolarizing noise several states are significantly more robust than
random states.",1310.7336v2
2013-11-22,Complexity of the minimum-time damping of a physical pendulum,"We study the minimum-time damping of a physical pendulum by means of a
bounded control. In the similar problem for a linear oscillator each optimal
trajectory possesses a finite number of control switchings from the maximal to
the minimal value. If one considers simultaneously all optimal trajectories
with any initial state, the number of switchings can be arbitrary large. We
show that for the nonlinear pendulum there is a uniform bound for the switching
number for all optimal trajectories. We find asymptotics for this bound as the
control amplitude goes to zero.",1311.5729v1
2013-12-16,Local Energy Decay for the Damped Wave Equation,"We prove local energy decay for the damped wave equation on R^d. The problem
which we consider is given by a long range metric perturbation of the Euclidean
Laplacian with a short range absorption index. Under a geometric control
assumption on the dissipation we obtain an almost optimal polynomial decay for
the energy in suitable weighted spaces. The proof relies on uniform estimates
for the corresponding ""resolvent"", both for low and high frequencies. These
estimates are given by an improved dissipative version of Mourre's commutators
method.",1312.4483v1
2013-12-23,Photonic tuning of quasi-particle decay in a superfluid,"We show that the damping rate of elementary excitations of hybrid systems
close to a phase transition can undergo a remarkable resonance like enhancement
before mode softening takes place. In particular, we consider the friction of a
collective density wave in a homogeneous superfluid of weakly interacting
bosonic atoms coupled to the electromagnetic field of a single mode optical
resonator. Here the Beliaev damping can thus be controlled by an external laser
drive and be enhanced by several orders of magnitude.",1312.6719v1
2014-01-04,Entanglement and quantum teleportation via decohered tripartite entangled states,"The entanglement behavior of two classes of multi-qubit system, GHZ and GHZ
like states passing through a generalized amplitude damping channel is
discussed. Despite this channel causes degradation of the entangled properties
and consequently their abilities to perform quantum teleportation, one can
always improve the lower values of the entanglement and the fidelity of the
teleportrd state by controlling on Bell measurements, analyzer angle and
channel's strength. Using GHZ-like state within a generalized amplitude damping
channel is much better than using the normal GHZ-state, where the decay rate of
entanglement and the fidelity of the teleported states are smaller than those
depicted for GHZ state.",1401.0796v1
2014-02-11,New approach for Damping in a squeezed bath and its time evolution through Complete Class of Gaussian Quasi-distributions,"By virtue of the thermal entangled states representation of density operator
and using dissipative interaction picture we solve the master equation of a
driven damped harmonic oscillator in a squeezed bath. We show that the
essential part of the dynamics can be expressed by the convolution of initial
Wigner function with a special kind of normalized Gaussian in phase space and
relate the dynamics with the change of Gaussian ordering of density operator.",1402.2545v1
2014-02-11,New approach for solving master equations of density operator for the Jaynes Cummings Model with Cavity Damping,"By introducing thermal entangled state representation which can map master
equations of density operator in quantum statistics as state vector evolution
equations and using dissipative interaction picture we solve the master
equation of J-C model with cavity damping. In addition we derive the Wigner
function for density operator when the atom is initially in the up state and
the cavity mode is in coherent state.",1402.2556v1
2014-02-19,Superfluid Bloch dynamics in an incommensurate lattice,"We investigate the interplay of disorder and interactions in the accelerated
transport of a Bose-Einstein condensate through an incommensurate optical
lattice. We show that interactions can effectively cancel the damping of Bloch
oscillations due to the disordered potential and we provide a simple model to
qualitatively capture this screening effect. We find that the characteristic
interaction energy, above which interactions and disorder cooperate to enhance,
rather than reduce, the damping of Bloch oscillations, coincides with the
average disorder depth. This is consistent with results of a mean-field
simulation.",1402.4830v1
2014-02-21,Weakly damped acoustic plasmon mode in transition metal dichalcogenides with Zeeman splitting,"We analyze the effect of a strong Zeeman field on the spectrum of collective
excitations of monolayer transition metal dichalcogenides. The combination of
the Dresselhaus type spin orbit coupling and an external Zeeman field result in
the lifting of the valley degeneracy in the valence band of these crystals. We
show that this lifting of the valley degeneracy manifests in the appearance of
an additional plasmon mode with linear in wavenumber dispersion along with the
standard square root in wavenumber mode. Despite this novel mode being subject
to the Landau damping, it corresponds to a well defined quasiparticle peak in
the spectral function of the electron gas.",1402.5274v1
2014-04-18,"On the Instability and Critical Damping Conditions, $kτ= 1/e$ and $kτ= π/2$ of the equation $\dotθ = -k θ(t-τ)$","In this note, I show that it is possible to use elementary mathematics,
instead of the machinery of Lambert function, Laplace Transform, or numerics,
to derive the instability condition, $k \tau = \pi/2$, and the critical damping
condition, $k\tau = 1/e$, for the time-delayed equation $\dot{\theta} = -k
\theta(t-\tau)$. I hope it will be useful for the new comers to this equation,
and perhaps even to the experts if this is a simpler method compared to other
versions.",1404.4763v1
2014-04-22,Nonlinear-damped Duffing oscillators having finite time dynamics,"A class of modified Duffing oscillator differential equations, having
nonlinear damping forces, are shown to have finite time dynamics, i.e., the
solutions oscillate with only a finite number of cycles, and, thereafter, the
motion is zero. The relevance of this feature is briefly discussed in
relationship to the mathematical modeling, analysis, and estimation of
parameters for the vibrations of carbon nano-tubes and graphene sheets, and
macroscopic beams and plates.",1404.5596v1
2014-08-20,Initial Layer and Relaxation Limit of Non-Isentropic Compressible Euler Equations with Damping,"In this paper, we study the relaxation limit of the relaxing Cauchy problem
for non-isentropic compressible Euler equations with damping in
multi-dimensions. We prove that the velocity of the relaxing equations
converges weakly to that of the relaxed equations, while other variables of the
relaxing equations converges strongly to the corresponding variables of the
relaxed equations. We show that as relaxation time approaches 0, there exists
an initial layer for the ill-prepared data, the convergence of the velocity is
strong outside the layer; while there is no initial layer for the well-prepared
data, the convergence of the velocity is strong near t=0.",1408.4784v1
2014-08-26,Exponential decay for the damped wave equation in unbounded domains,"We study the decay of the semigroup generated by the damped wave equation in
an unbounded domain. We first prove under the natural geometric control
condition the exponential decay of the semigroup. Then we prove under a weaker
condition the logarithmic decay of the solutions (assuming that the initial
data are smoother). As corollaries, we obtain several extensions of previous
results of stabilisation and control.",1408.6054v2
2014-10-03,Relaxation of regularity for the Westervelt equation by nonlinear damping with application in acoustic-acoustic and elastic-acoustic coupling,"In this paper we show local (and partially global) in time existence for the
Westervelt equation with several versions of nonlinear damping. This enables us
to prove well-posedness with spatially varying $L_\infty$-coefficients, which
includes the situation of interface coupling between linear and nonlinear
acoustics as well as between linear elasticity and nonlinear acoustics, as
relevant, e.g., in high intensity focused ultrasound (HIFU) applications.",1410.0797v1
2014-10-13,Vortex gyration mediated by spin waves driven by an out-of-plane oscillating magnetic field,"In this letter we address the vortex core dynamics involved in gyration
excitation and damping change by out-of-plane oscillating magnetic fields. When
the vortex core is at rest under the effect of in-plane bias magnetic fields,
the spin waves excited by the perpendicular magnetic field can induce obvious
vortex gyration. When simultaneously excite spin waves and vortex gyrotropic
motion, the gyration damping changes. Analysis of the system energy allows us
to explain the origin of the spin-wave-mediated vortex gyration.",1410.3230v1
2014-10-23,Non-equilibrium thermodynamics approach to open quantum systems,"Open quantum systems are studied from the thermodynamical point of view
unifying the principle of maximum informational entropy and the hypothesis of
relaxation times hierarchy. The result of the unification is a non-Markovian
and local in time master equation that provides a direct connection of
dynamical and thermodynamical properties of open quantum systems. The power of
the approach is illustrated with the application to the damped harmonic
oscillator and the damped driven two-level system resulting in analytical
expressions for the non-Markovian and non-equilibrium entropy and inverse
temperature.",1410.6312v2
2014-10-27,Linear Inviscid Damping for Monotone Shear Flows,"In this article, we prove linear stability, scattering and inviscid damping
with optimal decay rates for the linearized 2D Euler equations around a large
class of strictly monotone shear flows, $(U(y),0)$, in a periodic channel under
Sobolev perturbations. Here, we consider the settings of both an infinite
periodic channel of period $L$, $\mathbb{T}_{L}\times \mathbb{R}$, as well as a
finite periodic channel, $\mathbb{T}_{L} \times [0,1]$, with impermeable walls.
The latter setting is shown to not only be technically more challenging, but to
exhibit qualitatively different behavior due to boundary effects.",1410.7341v2
2014-11-08,Damping of liquid sloshing by foams: from everyday observations to liquid transport,"We perform experiments on the sloshing dynamics of liquids in a rectangular
container submitted to an impulse. We show that when foam is placed on top of
the liquid the oscillations of the free interface are significantly damped. The
ability to reduce sloshing and associated splashing could find applications in
numerous industrial processes involving liquid transport.",1411.2123v1
2014-11-17,A geometric mesh smoothing algorithm related to damped oscillations,"We introduce a smoothing algorithm for triangle, quadrilateral, tetrahedral
and hexahedral meshes whose centerpiece is a simple geometric triangle
transformation. The first part focuses on the mathematical properties of the
element transformation. In particular, the transformation gives rise directly
to a continuous model given by a system of coupled damped oscillations. Derived
from this physical model, adaptive parameters are introduced and their benefits
presented. The second part discusses the mesh smoothing algorithm based on the
element transformation and its numerical performance on example meshes.",1411.4390v3
2014-12-05,Exponential dephasing of oscillators in the Kinetic Kuramoto Model,"We study the kinetic Kuramoto model for coupled oscillators with coupling
constant below the synchronization threshold. We manage to prove that, for any
analytic initial datum, if the interaction is small enough, the order parameter
of the model vanishes exponentially fast, and the solution is asymptotically
described by a free flow. This behavior is similar to the phenomenon of Landau
damping in plasma physics. In the proof we use a combination of techniques from
Landau damping and from abstract Cauchy-Kowalewskaya theorem.",1412.1923v1
2014-12-23,Selftrapping triggered by losses in cavity QED,"In a coupled cavity QED network model, we study the transition from a
localized super fluid like state to a delocalized Mott insulator like state,
triggered by losses. Without cavity losses, the transition never takes place.
Further, if one measures the quantum correlations between the polaritons via
the negativity, we find a critical cavity damping constant, above which the
negativity displays a single peak in the same time region where the transition
takes place. Additionally, we identify two regions in the parameter space,
where below the critical damping, oscillations of the initial localized state
are observed along with a multipeaked negativity, while above the critical
value, the oscillations die out and the transition is witnessed by a neat
single peaked negativity.",1412.7495v1
2015-01-07,Two-photon lasing by a superconducting qubit,"We study the response of a magnetic-field-driven superconducting qubit
strongly coupled to a superconducting coplanar waveguide resonator. We observed
a strong amplification/damping of a probing signal at different resonance
points corresponding to a one and two-photon emission/absorption. The sign of
the detuning between the qubit frequency and the probe determines whether
amplification or damping is observed. The larger blue detuned driving leads to
two-photon lasing while the larger red detuning cools the resonator. Our
experimental results are in good agreement with the theoretical model of qubit
lasing and cooling at the Rabi frequency.",1501.01543v1
2015-02-02,Enhanced oscillation lifetime of a Bose-Einstein condensate in the 3D/1D crossover,"We have measured the damped motion of a trapped Bose-Einstein condensate,
oscillating with respect to a thermal cloud. The cigar-shaped trapping
potential provides enough transverse confinement that the dynamics of the
system are intermediate between three-dimensional and one-dimensional. We find
that oscillations persist for longer than expected for a three-dimensional gas.
We attribute this to the suppressed occupation of transverse momentum states,
which are essential for damping.",1502.00430v2
2015-02-03,Nonequilibrium dynamics of an ultracold dipolar gas,"We study the relaxation and damping dynamics of an ultracold, but not quantum
degenerate, gas consisting of dipolar particles. These simulations are
performed using a direct simulation Monte Carlo method and employing the highly
anisotropic differential cross section of dipoles in the Wigner threshold
regime. We find that both cross-dimensional relaxation and damping of breathing
modes occur at rates that are strongly dependent on the orientation of the
dipole moments relative to the trap axis. The relaxation simulations are in
excellent agreement with recent experimental results in erbium. The results
direct our interest toward a less explored regime in dipolar gases where
interactions are dominated by collision processes rather than mean-field
interactions.",1502.00960v1
2015-02-01,"On the Stability of Cylindrical Tangential Discontinuity, Generation and Damping of Helical Waves","Stability of cylindrical interface between two ideal incompressible fluids,
including the magnetic field, surface tension and gravitational field is
studied in linear approximation. We found that helical waves arising both in
plasma comet tails and on the vertical cylindrical water jet in the air are
described by the same dispersion equation where the comet tail magnetic field
plays the same stabilizing role as surface tension for water jet. Hence they
represent the same phenomenon of Kelvin-Helmholtz instability. Thus helical
waves in comet tails and astrophysical jets may be simulated in the laboratory.
The resonance nature of the Kelvin- instability damping is demonstrated.",1502.00989v1
2015-03-04,On the Lewis-Riesenfeld (Dodonov-Man'ko) invariant method,"We revise the Lewis-Riesenfeld invariant method for solving the quantum
time-dependent harmonic oscillator in light of the Quantum Arnold
Transformation previously introduced and its recent generalization to the
Quantum Arnold-Ermakov-Pinney Transformation. We prove that both methods are
equivalent and show the advantages of the Quantum Arnold-Ermakov-Pinney
transformation over the Lewis-Riesenfeld invariant method. We show that, in the
quantum time-dependent and damped harmonic oscillator, the invariant proposed
by Dodonov & Man'ko is more suitable and provide some examples to illustrate
it, focusing on the damped case.",1503.01371v1
2015-03-06,On the strongly damped wave equation with constraint,"A weak formulation for the so-called ""semilinear strongly damped wave
equation with constraint"" is introduced and a corresponding notion of solution
is defined. The main idea in this approach consists in the use of duality
techniques in Sobolev-Bochner spaces, aimed at providing a suitable
""relaxation"" of the constraint term. A global in time existence result is
proved under the natural condition that the initial data have finite ""physical""
energy.",1503.01911v1
2015-03-23,Spin-Orbit Torques in Two-Dimensional Rashba Ferromagnets,"Magnetization dynamics in single-domain ferromagnets can be triggered by
charge current if spin-orbit coupling is sufficiently strong. We apply
functional Keldysh theory to investigate Rashba spin-orbit torques in metallic
two-dimensional ferromagnets. A reactive, anti-damping-like spin-orbit torque
as well as a dissipative, field-like torque are calculated microscopically, to
the leading order in the spin-orbit interaction strength. By calculating the
first vertex correction we show that the intrinsic anti-damping-like torque
vanishes unless the scattering rates are spin-dependent.",1503.06872v2
2015-04-18,Global Dirichlet Heat Kernel Estimates for Symmetric Lévy Processes in Half-space,"In this paper, we derive explicit sharp two-sided estimates for the Dirichlet
heat kernels of a large class of symmetric (but not necessarily rotationally
symmetric) L\'evy processes on half spaces for all $t>0$. These L\'evy
processes may or may not have Gaussian component. When L\'evy density is
comparable to a decreasing function with damping exponent $\beta$,our estimate
is explicit in terms of the distance to the boundary, the L\'evy exponent and
the damping exponent $\beta$ of L\'evy density.",1504.04673v2
2015-05-05,The transition from the classical to the quantum regime in nonlinear Landau damping,"Starting from the Wigner-Moyal equation coupled to Poisson's equation, a
simplified set of equations describing nonlinear Landau damping of Langmuir
waves is derived. This system is studied numerically, with a particular focus
on the transition from the classical to the quantum regime. In the quantum
regime several new features are found. This includes a quantum modified bounce
frequency, and the discovery that bounce-like amplitude oscillations can take
place even in the absence of trapped particles. The implications of our results
are discussed.",1505.01381v1
2015-05-08,The amplification of weak measurements under quantum noise,"The influence of outside quantum noises on the amplification of weak
measurements is investigated. Three typical quantum noises are discussed. The
maximum values of the pointer's shifts decrease sharply with the strength of
the depolarizing channel and phase damping. In order to obtain significant
amplified signals, the preselection quantum systems must be kept away from the
two quantum noises. Interestingly, the amplification effect is immune to the
amplitude damping noise.",1505.01911v1
2015-05-27,Local energy decay and smoothing effect for the damped Schr{ö}dinger equation,"We prove the local energy decay and the smoothing effect for the damped
Schr{\""o}dinger equation on R^d. The self-adjoint part is a Laplacian
associated to a long-range perturbation of the flat metric. The proofs are
based on uniform resolvent estimates obtained by the dissipative Mourre method.
All the results depend on the strength of the dissipation which we consider.",1505.07200v1
2015-05-27,Logarithmic stability in determining a boundary coefficient in an ibvp for the wave equation,"In [2] we introduced a method combining together an observability inequality
and a spectral decomposition to get a logarithmic stability estimate for the
inverse problem of determining both the potential and the damping coefficient
in a dissipative wave equation from boundary measurements. The present work
deals with an adaptation of that method to obtain a logarithmic stability
estimate for the inverse problem of determining a boundary damping coefficient
from boundary measurements. As in our preceding work, the different boundary
measurements are generated by varying one of the initial conditions.",1505.07248v1
2015-06-01,Local decay for the damped wave equation in the energy space,"We improve a previous result about the local energy decay for the damped wave
equation on R^d. The problem is governed by a Laplacian associated with a long
range perturbation of the flat metric and a short range absorption index. Our
purpose is to recover the decay O(t^{--d+$\epsilon$}) in the weighted energy
spaces. The proof is based on uniform resolvent estimates, given by an improved
version of the dissipative Mourre theory. In particular we have to prove the
limiting absorption principle for the powers of the resolvent with inserted
weights.",1506.00377v1
2015-06-03,Giant Phonon Anomaly associated with Superconducting Fluctuations in the Pseudogap Phase of Cuprates,"The opening of the pseudogap in underdoped cuprates breaks up the Fermi
surface, which may lead to a breakup of the d-wave order parameter into two
subband amplitudes and a low energy Leggett mode due to phase fluctuations
between them. This causes a large increase in the temperature range of
superconducting fluctuations with an overdamped Leggett mode. Almost resonant
scattering of inter-subband phonons to a state with a pair of Leggett modes
causes anomalously strong damping. In the ordered state, the Leggett mode
develops a finite energy, suppressing the anomalous phonon damping but leading
to an anomaly in the phonon dispersion.",1506.01258v1
2015-06-06,On higher regularity for the Westervelt equation with strong nonlinear damping,"We show higher interior regularity for the Westervelt equation with strong
nonlinear damping term of the $q$-Laplace type. Secondly, we investigate an
interface coupling problem for these models, which arise, e.g., in the context
of medical applications of high intensity focused ultrasound in the treatment
of kidney stones. We show that the solution to the coupled problem exhibits
piecewise $H^2$ regularity in space, provided that the gradient of the acoustic
pressure is essentially bounded in space and time on the whole domain. This
result is of importance in numerical approximations of the present problem, as
well as in gradient based algorithms for finding the optimal shape of the
focusing acoustic lens in lithotripsy.",1506.02125v1
2015-06-08,Intermode-coupling modulation in the fermion-boson model: heating effects in the BCS regime,"Heating induced by an oscillating modulation of the interaction strength in
an atomic Fermion pair condensate is analyzed. The coupled fermion-boson model,
generalized by incorporating a time-dependent intermode coupling through a
magnetic Feshbach resonance, is applied. The dynamics is analytically
characterized in a perturbative scheme. The results account for experimental
findings which have uncovered a damped and delayed response of the condensate
to the modulation. The delay is due to the variation of the quasiparticle
energies and the subsequent relaxation of the condensate. The detected damping
results from the excitations induced by a nonadiabatic modulation: for driving
frequencies larger than twice the pairing gap, quasiparticles are generated,
and, consequently, heating sets in.",1506.02612v1
2015-06-22,N-body description of Debye shielding and Landau damping,"This paper brings further insight into the recently published N-body
description of Debye shielding and Landau damping [Escande D F, Elskens Y and
Doveil F 2014 Plasma Phys. Control. Fusion 57 025017]. Its fundamental equation
for the electrostatic potential is derived in a simpler and more rigorous way.
Various physical consequences of the new approach are discussed, and this
approach is compared with the seminal one by Pines and Bohm [Pines D and Bohm D
1952 Phys. Rev. 85 338--353].",1506.06468v2
2015-07-23,Millisecond newly born pulsars as efficient accelerators of electrons,"The newly born millisecond pulsars are investigated as possible energy
sources for creating ultra-high energy electrons. The transfer of energy from
the star rotation to high energy electrons takes place through the Landau
damping of centrifugally driven (via a two stream instability) electrostatic
Langmuir waves. Generated in the bulk magnetosphere plasma, such waves grow to
high amplitudes, and then damp, very effectively, on relativistic electrons
driving them to even higher energies. We show that the rate of transfer of
energy is so efficient that no energy losses might affect the mechanism of
particle acceleration; the electrons might achieve energies of the order of
10^{18}eV for parameters characteristic of a young star.",1507.06415v1
2015-07-28,Stability of solutions to nonlinear wave equations with switching time-delay,"In this paper we study well-posedness and asymptotic stability for a class of
nonlinear second-order evolution equations with intermittent delay damping.
More precisely, a delay feedback and an undelayed one act alternately in time.
We show that, under suitable conditions on the feedback operators, asymptotic
stability results are available. Concrete examples included in our setting are
illustrated. We give also stability results for an abstract model with
alternate positive-negative damping, without delay.",1507.07787v1
2015-08-10,Theory of the strongly-damped quantum harmonic oscillator,"We analyse the properties of a strongly-damped quantum harmonic oscillator by
means of an exact diagonalisation of the full Hamiltonian, including both the
oscillator and the reservoir degrees of freedom to which it is coupled. Many of
the properties of the oscillator, including its steady-state properties and
entanglement with the reservoir can be understood and quantified in terms of a
simple probability density, which we may associate with the ground-state
frequency spectrum of the oscillator.",1508.02442v1
2015-08-20,Bump-on-tail instability of twisted excitations in rotating cold atomic clouds,"We develop a kinetic theory for twisted density waves (phonons), carrying a
finite amount of orbital angular momentum, in large magneto optical traps,
where the collective processes due to the exchange of scattered photons are
considered. Explicit expressions for the dispersion relation and for the
kinetic (Landau) damping are derived and contributions from the orbital angular
momentum are discussed. We show that for rotating clouds, exhibiting
ring-shaped structures, phonons carrying orbital angular momentum can cross the
instability threshold and grow out of noise, while the usual plane wave
solutions are kinetically damped.",1508.05127v1
2015-08-28,The inviscid limit for the Landau-Lifshitz-Gilbert equation in the critical Besov space,"We prove that in dimensions three and higher the Landau-Lifshitz- Gilbert
equation with small initial data in the critical Besov space is globally
wellposed in a uniform way with respect to the Gilbert damping parameter. Then
we show that the global solution converges to that of the Schrodinger maps in
the natural space as the Gilbert damping term vanishes. The proof is based on
some studies on the derivative Ginzburg-Landau equations.",1508.07118v3
2015-09-30,Approximation of Invariant Measure for Damped Stochastic Nonlinear Schrödinger Equation via an Ergodic Numerical Scheme,"In order to inherit numerically the ergodicity of the damped stochastic
nonlinear Schr\""odinger equation with additive noise, we propose a fully
discrete scheme, whose spatial direction is based on spectral Galerkin method
and temporal direction is based on a modification of the implicit Euler scheme.
We not only prove the unique ergodicity of the numerical solutions of both
spatial semi-discretization and full discretization, but also present error
estimations on invariant measures, which gives order $2$ in spatial direction
and order ${\frac12}$ in temporal direction.",1509.09148v2
2015-10-02,Cavity and HOM Coupler Design for CEPC,"In this paper we will show a cavity and higher order mode (HOM) coupler
designing scheme for the Circular Electron-Positron Collider (CEPC) main ring.
The cavity radio frequency (RF) design parameters are showed in this paper. The
HOM power is calculated based on the beam parameters in the Preliminary
Conceptual Design Report (Pre-CDR). The damping results of the higher order
modes (HOMs) and same order modes (SOMs) show that they are reached the damping
requirements for beam stability.",1510.00467v1
2015-11-08,Upper semicontinuity of pullback attractors for damped wave equations,"In this paper, we study the upper semicontinuity of pullback attractors for a
strongly damped wave equation. In particular, under some proper assumptions, we
prove that, the pullback attractor $\{A_\varepsilon(t)\}_{t\in\mathbb R}$} of
Eq.(1.1) with $\varepsilon\in[0,1]$ satisfies that for any $[a,b]\subset\mathbb
R$ and $\varepsilon_0\in[0,1]$, $\lim_{\varepsilon\to\varepsilon_0}
\sup_{t\in[a,b]} \mathrm{dist}_{H_0^1\times L^2} (A_\varepsilon(t),
A_{\varepsilon_0}(t))=0$, and $\cup_{t\in[a,b]} \cup_{\varepsilon\in[0,1]}
A_\varepsilon(t)$ is precompact in $H_0^1 (\Omega) \times L^2(\Omega)$.",1511.02481v2
2015-11-12,"Strong trajectory and global $\mathbf{W^{1,p}}$-attractors for the damped-driven Euler system in $\mathbb R^2$","We consider the damped and driven two-dimensional Euler equations in the
plane with weak solutions having finite energy and enstrophy. We show that
these (possibly non-unique) solutions satisfy the energy and enstrophy
equality. It is shown that this system has a strong global and a strong
trajectory attractor in the Sobolev space $H^1$. A similar result on the strong
attraction holds in the spaces $H^1\cap\{u:\ \|\mathrm{curl}
u\|_{L^p}<\infty\}$ for $p\ge2$.",1511.03873v1
2015-11-14,Infinite energy solutions for critical wave equation with fractional damping in unbounded domains,"This work is devoted to infinite-energy solutions of semi-linear wave
equations in unbounded smooth domains of $\mathbb{R}^3$ with fractional damping
of the form $(-\Delta_x+1)^\frac{1}{2}\partial_t u$. The work extends
previously known results for bounded domains in finite energy case.
Furthermore, well-posedness and existence of locally-compact smooth attractors
for the critical quintic non-linearity are obtained under less restrictive
assumptions on non-linearity, relaxing some artificial technical conditions
used before. This is achieved by virtue of new type Lyapunov functional that
allows to establish extra space-time regularity of solutions of Strichartz
type.",1511.04592v1
2015-11-14,Parametric resonance induced chaos in magnetic damped driven pendulum,"A damped driven pendulum with a magnetic driving force, appearing from a
solenoid, where ac current flows is considered. The solenoid acts on the
magnet, which is located at the free end of the pendulum. In this system, the
existence and interrelation of chaos and parametric resonance is theoretically
examined. Derived analytical results are supported by numerical simulations and
conducted experiments.",1511.04593v2
2015-11-19,Periodic damping gives polynomial energy decay,"Let $u$ solve the damped Klein--Gordon equation $$ \big( \partial_t^2-\sum
\partial_{x_j}^2 +m \text{Id} +\gamma(x) \partial_t \big) u=0 $$ on
$\mathbb{R}^n$ with $m>0$ and $\gamma\geq 0$ bounded below on a $2 \pi
\mathbb{Z}^n$-invariant open set by a positive constant. We show that the
energy of the solution $u$ decays at a polynomial rate. This is proved via a
periodic observability estimate on $\mathbb{R}^n.$",1511.06144v5
2016-01-18,Stabilizing the Long-time Behavior of the Navier-Stokes Equations and Damped Euler Systems by Fast Oscillating Forces,"The paper studies the issue of stability of solutions to the Navier-Stokes
and damped Euler systems in periodic boxes. We show that under action of fast
oscillating-in- time external forces all two dimensional regular solutions
converge to a time periodic flow. Unexpectedly, effects of stabilization can be
also obtained for systems with stationary forces with large total momentum
(average of the velocity). Thanks to the Galilean transformation and space
boundary conditions, the stationary force changes into one with time
oscillations. In the three dimensional case we show an analogical result for
weak solutions to the Navier- Stokes equations.",1601.04612v1
2016-01-27,Design of a large dynamic range readout unit for the PSD detector of DAMPE,"A large dynamic range is required by the Plastic Scintillator Detector (PSD)
of DArk Matter Paricle Explorer (DAMPE), and a double-dynode readout has been
developed. To verify this design, a prototype detector module has been
constructed and tested with cosmic rays and heavy ion beams. The results match
with the estimation and the readout unit could easily cover the required
dynamic range.",1601.07234v1
2016-02-09,Engineering and Suppression of Decoherence in Two Qubit Systems,"In this work, two experimentally feasible methods of decoherence
engineering-one based on the application of stochastic classical kicks and the
other based on temporally randomized pulse sequences are combined. A different
coupling interaction is proposed, which leads to amplitude damping as compared
to existing methods which model phase damping, utilizing the $zz$ coupling
interaction. The decoherence process on combining the stochastic kick method
and the randomized pulse sequence method and the effectiveness of dynamical
decoupling under these coupling interactions are analyzed. Finally, a
counter-intuitive result where decoherence is suppressed in the presence of two
noise sources under certain resonant conditions is presented.",1602.03026v1
2016-02-10,Attractors for the strongly damped wave equation with $p$-Laplacian,"This paper is concerned with the initial boundary value problem for one
dimensional strongly damped wave equation involving $p$-Laplacian. For $p>2$,
we establish the existence of weak local attractors for this problem in
$W_{0}^{1,p}(0,1)\times L^{2}(0,1)$. Under restriction $2<p<4$, we prove that
the semigroup, generated by the considered problem, possesses a strong global
attractor in $W_{0}^{1,p}(0,1)\times L^{2}(0,1)$ and this attractor is a
bounded subset of $W^{1,\infty }(0,1)\times W^{1,\infty }(0,1)$.",1602.03339v3
2016-02-11,Renormalization Group Study of a Fragile Fermi liquid in $1+ε$ dimensions,"We present a calculation of the low energy Greens function in $1+\epsilon$
dimensions using the method of extended poor man's scaling, developed here. We
compute the wave function renormalization $Z(\omega)$ and also the decay rate
near the Fermi energy. Despite the lack of $\omega^2$ damping characteristic of
3-dimensional Fermi liquids, we show that quasiparticles do exist in
$1+\epsilon$ dimensions, in the sense that the quasiparticle weight $Z$ is
finite and that the damping rate is smaller than the energy. We explicitly
compute the crossover from this behavior to a 1-dimensional type
Tomonaga-Luttinger liquid behavior at higher energies.",1602.03613v2
2016-02-20,Movement of time-delayed hot spots in Euclidean space,"We investigate the shape of the solution of the Cauchy problem for the damped
wave equation. In particular, we study the existence, location and number of
spatial maximizers of the solution. Studying the shape of the solution of the
damped wave equation, we prepare a decomposed form of the solution into the
heat part and the wave part. Moreover, as its another application, we give
$L^p$-$L^q$ estimates of the solution.",1602.06376v1
2016-03-04,Optical realization of the dissipative quantum oscillator,"An optical realization of the damped quantum oscillator, based on transverse
light dynamics in an optical resonator with slowly-moving mirrors, is
theoretically suggested. The optical resonator setting provides a simple
implementation of the time-dependent Caldirola-Kanai Hamiltonian of the
dissipative quantum oscillator, and enables to visualize the effects of damped
oscillations in the classical (ray optics) limit and wave packet collapse in
the quantum (wave optics) regime.",1603.01364v1
2016-03-08,Modifications of the Lifshitz-Kosevich formula in two-dimensional Dirac systems,"Starting from the Luttinger-Ward functional we derive an expression for the
oscillatory part of the grand potential of a two dimensional Dirac system in a
magnetic field. We perform the computation for the clean and the disordered
system, and we study the effect of electron-electron interactions on the
oscillations. Unlike in the two dimensional electron gas (2DEG), a finite
temperature and impurity scattering also affects the oscillation frequency.
Furthermore, we find that in graphene, compared to the 2DEG, additional
interaction induced damping effects occur: to two-loop order electron-electron
interactions do lead to an additional damping factor in the amplitude of the
Lifshitz-Kosevich-formula.",1603.02559v1
2016-03-23,Landau damping for the linearized Vlasov Poisson equation in a weakly collisional regime,"In this paper, we consider the linearized Vlasov-Poisson equation around an
homogeneous Maxwellian equilibrium in a weakly collisional regime: there is a
parameter $\eps$ in front of the collision operator which will tend to $0$.
Moreover, we study two cases of collision operators, linear Boltzmann and
Fokker-Planck. We prove a result of Landau damping for those equations in
Sobolev spaces uniformly with respect to the collision parameter $\eps$ as it
goes to $0$.",1603.07219v2
2016-04-14,Higher order asymptotic expansions to the solutions for a nonlinear damped wave equation,"We study the Cauchy problem for a nonlinear damped wave equation. Under
suitable assumptions for the nonlinearity and the initial data, we obtain the
global solution which satisfies weighted $L^1$ and $L^\infty$ estimates.
Furthermore, we establish the higher order asymptotic expansion of the
solution. This means that we construct the nonlinear approximation of the
global solution with respect to the weight of the data. Our proof is based on
the approximation formula of the linear solution, which is given in [36], and
the nonlinear approximation theory for a nonlinear parabolic equation developed
by [18].",1604.04100v1
2016-04-18,On the pressureless damped Euler-Poisson equations with non-local forces: Critical thresholds and large-time behavior,"We analyse the one-dimensional pressureless Euler-Poisson equations with a
linear damping and non-local interaction forces. These equations are relevant
for modelling collective behavior in mathematical biology. We provide a sharp
threshold between the supercritical region with finite-time breakdown and the
subcritical region with global-in-time existence of the classical solution. We
derive an explicit form of solution in Lagrangian coordinates which enables us
to study the time-asymptotic behavior of classical solutions with the initial
data in the subcritical region.",1604.05229v1
2016-04-20,Reconstruction for multiwave imaging in attenuating media with large damping coefficient,"In this article we study the reconstruction problem in TAT/PAT on an
attenuating media. Namely, we prove a reconstruction procedure of the initial
condition for the damped wave equation via Neumann series that works for
arbitrary large smooth attenuation coefficients extending the result of Homan
in [1]. We also illustrate the theoretical result by including some numerical
experiments at the end of the paper.",1604.06068v3
2016-04-27,Temperature Dependence Calibration and Correction of the DAMPE BGO Electromagnetic Calorimeter,"A BGO electromagnetic calorimeter (ECAL) is built for the DArk Matter
Particle Explorer (DAMPE) mission. The effect of temperature on the BGO ECAL
was investigated with a thermal vacuum experiment. The light output of a BGO
crystal depends on temperature significantly. The temperature coefficient of
each BGO crystal bar has been calibrated, and a correction method is also
presented in this paper.",1604.08060v1
2016-06-03,Microscopic derivation of the one qubit Kraus operators for amplitude and phase damping,"This article presents microscopic derivation of the Kraus operators for (the
generalized) amplitude and phase damping process. Derivation is based on the
recently developed method [Andersson et al, J. Mod.Opt. 54, 1695 (2007)] which
concerns finite dimensional systems (e.g. qubit). The form of these operators
is usually estimated without insight into the microscopic details of the
dynamics. The behavior of the qubit dynamics is simulated and depicted via
Bloch sphere change.",1606.01145v1
2016-06-08,Energy Decay in a Wave Guide with Dissipation at Infinity,"We prove local and global energy decay for the wave equation in a wave guide
with damping at infinity. More precisely, the absorption index is assumed to
converge slowly to a positive constant, and we obtain the diffusive phenomenon
typical for the contribution of low frequencies when the damping is effective
at infinity. On the other hand, the usual Geometric Control Condition is not
necessarily satisfied so we may have a loss of regularity for the contribution
of high frequencies. Since our results are new even in the Euclidean space, we
also state a similar result in this case.",1606.02549v2
2016-06-29,Damped Topological Magnons in the Kagomé-Lattice Ferromagnets,"We demonstrate that interactions can substantially undermine the
free-particle description of magnons in ferromagnets on geometrically
frustrated lattices. The anharmonic coupling, facilitated by the
Dzyaloshinskii-Moriya interaction, and a highly-degenerate two-magnon continuum
yield a strong, non-perturbative damping of the high-energy magnon modes. We
provide a detailed account of the effect for the $S=1/2$ ferromagnet on the
kagom\'e lattice and propose further experiments.",1606.09249v3
2016-07-06,Asymptotic profiles of solutions for structural damped wave equations,"In this paper, we obtain several asymptotic profiles of solutions to the
Cauchy problem for structurally damped wave equations $\partial_{t}^{2} u -
\Delta u + \nu (-\Delta)^{\sigma} \partial_{t} u=0$, where $\nu >0$ and $0<
\sigma \le1$. Our result is the approximation formula of the solution by a
constant multiple of a special function as $t \to \infty$, which states that
the asymptotic profiles of the solutions are classified into $5$ patterns
depending on the values $\nu$ and $\sigma$.",1607.01839v1
2016-09-20,H{ö}lder stability in determining the potential and the damping coefficient in a wave equation,"We improve the preceding results obtained by the first and the second authors
in [3]. They concern the stability issue of the inverse problem that consists
in determining the potential and the damping coefficient in a wave equation
from an initial-to-boundary operator. We partially modify the arguments in [3]
to show that actually we have H{\""o}lder stability instead of logarithmic
stability.",1609.06102v1
2016-10-09,Beam halo study on ATF damping ring,"Halo distribution is a key topic for background study. This paper has
developed an analytical method to give an estimation of ATF beam halo
distribution. The equilibrium particle distribution of the beam tail in the ATF
damping ring is calculated analytically with different emittance and different
vacuum degree. The analytical results agree the measurements very well. This is
a general method which can be applied to any electron rings.",1610.02624v1
2016-10-11,"Damping of hard excitations in strongly coupled $\mathcal N\,{=}\,4$ plasma","The damping of high momentum excitations in strongly coupled maximally
supersymmetric Yang-Mills plasma is studied. Previous calculations of the
asymptotic behavior of the quasinormal mode spectrum are extended and
clarified. We confirm that subleading corrections to the lightlike dispersion
relation $\omega({\bf q}) = |{\bf q}|$ have a universal $|{\bf q}|^{-1/3}$
form. Sufficiently narrow, weak planar shocks may be viewed as coherent
superpositions of short wavelength quasinormal modes. The attenuation and
evolution in profile of narrow planar shocks are examined as an application of
our results.",1610.03491v1
2016-10-24,Assessing the quantumness of a damped two-level system,"We perform a detailed analysis of the nonclassical properties of a damped
two-level system. We compute and compare three different criteria of
quantumness, the $l_1$-norm of coherence, the Leggett- Garg inequality and a
quantum witness based on the no-signaling in time condition. We show that all
three quantum indicators decay exponentially in time as a result of the
coupling to the thermal reservoir. We further demonstrate that the
corresponding characteristic times are identical and given by the coherence
half-life. These results quantify how violations of Leggett-Garg inequalities
and nonzero values of the quantum witness are connected to the coherence of the
two-level system.",1610.07626v1
2016-10-26,Restoring genuine tripartite entanglement under local amplitude damping,"We investigate the possibility to restore genuine tripartite entanglement
under local amplitude damping. We show that it is possible to protect genuine
entanglement using CNOT and Hadamard gates. We analyze several ordering of such
recovery operations. We find that for recovery operations applied after
exposing qubits to decoherence, there is no enhancement in lifetime of genuine
entanglement. Actual retrieval of entanglement is only possible when reversal
scheme is applied before and after the decoherence process. We find that
retrieval of entanglement for mixture of $|\widetilde{W}\rangle$ state with
white noise is more evident than the respective mixture of $|W\rangle$ state.
We also find the retrieval of entanglement for similar mixture of $|GHZ\rangle$
state as well.",1610.08280v1
2016-10-27,Linear Inviscid Damping for Couette Flow in Stratified Fluid,"We study the inviscid damping of Couette flow with an exponentially
stratified density. The optimal decay rates of the velocity field and the
density are obtained for general perturbations with minimal regularity. For
Boussinesq approximation model, the decay rates we get are consistent with the
previous results in the literature. We also study the decay rates for the full
Euler equations of stratified fluids, which were not studied before. For both
models, the decay rates depend on the Richardson number in a very similar way.
Besides, we also study the dispersive decay due to the exponential
stratification when there is no shear.",1610.08924v2
2017-02-22,Integration by parts of some non-adapted vector field from Malliavin's lifting approach,"In this paper we propose a lift of vector field $X$ on a Riemannian manifold
$M$ to a vector field $\tilde{X}$ on the curved Cameron-Martin space
$H\left(M\right)$ named orthogonal lift. The construction of this lift is based
on a least square spirit with respect to a metric on $H(M)$ reflecting the
damping effect of Ricci curvature. Its stochastic extension gives rise to a
non-adapted Cameron-Martin vector field on $W_o(M)$. In particular, if
$M=\mathbb{R}^d$ with Euclidean metric, then the damp disappears and the lift
reduces to the well-known Malliavin's lift. We establish an integration by
parts formula for these first order differential operators.",1702.06741v1
2017-02-23,The sharp lifespan estimate for semilinear damped wave equation with Fujita critical power in high dimensions,"This paper is concerned about the lifespan estimate to the Cauchy problem of
semilinear damped wave equations with the Fujita critical exponent in high
dimensions$(n\geq 4)$. We establish the sharp upper bound of the lifespan in
the following form \begin{equation}\nonumber\\ \begin{aligned}
T(\varepsilon)\leq \exp(C\varepsilon^{-\frac 2n}), \end{aligned} \end{equation}
by using the heat kernel as the test function.",1702.07073v2
2017-03-09,Off resonance coupling between a cavity mode and an ensemble of driven spins,"We study the interaction between a superconducting cavity and a spin
ensemble. The response of a cavity mode is monitored while simultaneously the
spins are driven at a frequency close to their Larmor frequency, which is tuned
to a value much higher than the cavity resonance. We experimentally find that
the effective damping rate of the cavity mode is shifted by the driven spins.
The measured shift in the damping rate is attributed to the retarded response
of the cavity mode to the driven spins. The experimental results are compared
with theoretical predictions and fair agreement is found.",1703.03311v1
2017-03-10,Negative Landau damping in bilayer graphene,"We theoretically demonstrate that a system formed by two coupled graphene
sheets enables a negative damping regime wherein graphene plasmons are pumped
by a DC current. This effect is triggered by electrons drifting through one of
the graphene sheets and leads to the spontaneous light emission (spasing) and
wave instabilities in the mid-infrared range. It is shown that there is a deep
link between the drift-induced instabilities and wave instabilities in moving
media, as both result from the hybridization of oscillators with oppositely
signed frequencies. With a thickness of few nanometers and wide spectral
tunability, the proposed structure may find interesting applications in
nanophotonic circuitry as an on-chip light source.",1703.03623v1
2017-03-10,Effects on the CMB from magnetic field dissipation before recombination,"Magnetic fields present before decoupling are damped due to radiative
viscosity. This energy injection affects the thermal and ionization history of
the cosmic plasma. The implications for the CMB anisotropies and polarization
are investigated for different parameter choices of a non helical stochastic
magnetic field. Assuming a Gaussian smoothing scale determined by the magnetic
damping wave number at recombination it is found that magnetic fields with
present day strength less than 0.1 nG and negative magnetic spectral indices
have a sizeable effect on the CMB temperature anisotropies and polarization.",1703.03650v1
2017-03-28,(1+1) Newton-Hooke Group for the Simple and Damped Harmonic Oscillator,"It is demonstrated that, in the framework of the orbit method, a simple and
damped harmonic oscillators are indistinguishable at the level of an abstract
Lie algebra. This opens a possibility for treating the dissipative systems
within the orbit method. In depth analysis of the coadjoint orbits of the
$(1+1)$ dimensional Newton-Hooke group are presented. Further, it is argued
that the physical interpretation is carried by a specific realisation of the
Lie algebra of smooth functions on a phase space rather than by an abstract Lie
algebra.",1703.09583v2
2017-08-09,Global well-posedness for the 2D Boussinesq equations with a velocity damping term,"In this paper, we prove global well-posedness of smooth solutions to the
two-dimensional incompressible Boussinesq equations with only a velocity
damping term when the initial data is close to an nontrivial equilibrium state
$(0,x_2)$. As a by-product, under this equilibrium state, our result gives a
positive answer to the question proposed by [ACWX] (see P.3597).",1708.02695v4
2017-08-18,Second sound in systems of one-dimensional fermions,"We study sound in Galilean invariant systems of one-dimensional fermions. At
low temperatures, we find a broad range of frequencies in which in addition to
the waves of density there is a second sound corresponding to ballistic
propagation of heat in the system. The damping of the second sound mode is
weak, provided the frequency is large compared to a relaxation rate that is
exponentially small at low temperatures. At lower frequencies the second sound
mode is damped, and the propagation of heat is diffusive.",1708.05733v2
2017-08-21,Equilibrium of a Brownian particle with coordinate dependent diffusivity and damping: Generalized Boltzmann distribution,"Fick's law for coordinate dependent diffusivity is derived. Corresponding
diffusion current in the presence of coordinate dependent diffusivity is
consistent with the form as given by Kramers-Moyal expansion. We have obtained
the equilibrium solution of the corresponding Smoluchowski equation. The
equilibrium distribution is a generalization of the Boltzmann distribution.
This generalized Boltzmann distribution involves an effective potential which
is a function of coordinate dependent diffusivity. We discuss various
implications of the existence of this generalized Boltzmann distribution for
equilibrium of systems with coordinate dependent diffusivity and damping.",1708.06132v5
2017-08-21,Global small solutions of 3D incompressible Oldroyd-B model without damping mechanism,"In this paper, we prove the global existence of small smooth solutions to the
three-dimensional incompressible Oldroyd-B model without damping on the stress
tensor. The main difficulty is the lack of full dissipation in stress tensor.
To overcome it, we construct some time-weighted energies based on the special
coupled structure of system. Such type energies show the partial dissipation of
stress tensor and the strongly full dissipation of velocity. In the view of
treating ""nonlinear term"" as a ""linear term"", we also apply this result to 3D
incompressible viscoelastic system with Hookean elasticity and then prove the
global existence of small solutions without the physical assumption (div-curl
structure) as previous works.",1708.06172v2
2018-02-26,Controllability and observability for non-autonomous evolution equations: the averaged Hautus test,"We consider the observability problem for non-autonomous evolution systems
(i.e., the operators governing the system depend on time). We introduce an
averaged Hautus condition and prove that for skew-adjoint operators it
characterizes exact observability. Next, we extend this to more general class
of operators under a growth condition on the associated evolution family. We
give an application to the Schr\""odinger equation with time dependent potential
and the damped wave equation with a time dependent damping coefficient.",1802.09224v1
2018-02-28,Global-in-time Stability of 2D MHD boundary Layer in the Prandtl-Hartmann Regime,"In this paper, we prove global existence of solutions with analytic
regularity to the 2D MHD boundary layer equations in the mixed Prandtl and
Hartmann regime derived by formal multi-scale expansion in \cite{GP}. The
analysis shows that the combined effect of the magnetic diffusivity and
transveral magnetic field on the boundary leads to a linear damping on the
tangential velocity field near the boundary. And this damping effect yields the
global in time analytic norm estimate in the tangential space variable on the
perturbation of the classical steady Hartmann profile.",1802.10494v3
2018-04-10,Motion of a superconducting loop in an inhomogeneous magnetic field: a didactic experiment,"We present an experiment conductive to an understanding of both Faraday's law
and the properties of the superconducting state. It consists in the analysis of
the motion of a superconducting loop moving under the influence of gravity in
an inhomogeneous horizontal magnetic field. Gravity, conservation of magnetic
flux, and friction combine to give damped harmonic oscillations. The measured
frequency of oscillation and the damping constant as a function of the magnetic
field strength (the only free parameter) are in good agreement with the
theoretical model.",1804.03553v1
2018-11-02,Nonlinear Damped Timoshenko Systems with Second Sound - Global Existence and Exponential Stability,"In this paper, we consider nonlinear thermoelastic systems of Timoshenko type
in a one-dimensional bounded domain. The system has two dissipative mechanisms
being present in the equation for transverse displacement and rotation angle -
a frictional damping and a dissipation through hyperbolic heat conduction
modelled by Cattaneo's law, respectively. The global existence of small, smooth
solutions and the exponential stability in linear and nonlinear cases are
established.",1811.01128v1
2018-11-14,Quantum witness of a damped qubit with generalized measurements,"We evaluate the quantum witness based on the no-signaling-in-time condition
of a damped two-level system for nonselective generalized measurements of
varying strength. We explicitly compute its dependence on the measurement
strength for a generic example. We find a vanishing derivative for weak
measurements and an infinite derivative in the limit of projective
measurements. The quantum witness is hence mostly insensitive to the strength
of the measurement in the weak measurement regime and displays a singular,
extremely sensitive dependence for strong measurements. We finally relate this
behavior to that of the measurement disturbance defined in terms of the
fidelity between pre-measurement and post-measurement states.",1811.06013v1
2019-05-07,Decay estimate for the solution of the evolutionary damped $p$-Laplace equation,"In this note, we study the asymptotic behavior, as $t$ tends to infinity, of
the solution $u$ to the evolutionary damped $p$-Laplace equation
\begin{equation*}
  u_{tt}+a\, u_t =\Delta_p u \end{equation*}
  with Dirichlet boundary values. Let $u^*$ denote the stationary solution with
same boundary values, then the $W^{1,p}$-norm of $u(t) - u^{*}$ decays for
large $t$ like $t^{-\frac{1}{(p-1)p}}$, in the degenerate case $ p > 2$.",1905.03597v2
2019-05-10,Asymptotic profiles for damped plate equations with rotational inertia terms,"We consider the Cauchy problem for plate equations with rotational inertia
and frictional damping terms. We will derive asymptotic profiles of the
solution in L^2-sense as time goes to infinity in the case when the initial
data have high and low regularity, respectively. Especially, in the low
regularity case of the initial data one encounters the regularity-loss
structure of the solutions, and the analysis is more delicate. We employ the
so-called Fourier splitting method combined with the explicit expression of the
solutions (high frequency estimates) and the method due to Ikehata (low
frequency estimates).",1905.04012v1
2019-05-20,Small perturbations for a Duffing-like evolution equation involving non-commuting operators,"We consider an abstract evolution equation with linear damping, a nonlinear
term of Duffing type, and a small forcing term. The abstract problem is
inspired by some models for damped oscillations of a beam subject to external
loads or magnetic fields, and shaken by a transversal force.
  The main feature is that very natural choices of the boundary conditions lead
to equations whose linear part involves two operators that do not commute.
  We extend to this setting the results that are known in the commutative case,
namely that for asymptotically small forcing terms all solutions are eventually
close to the three equilibrium points of the unforced equation, two stable and
one unstable.",1905.07942v1
2019-05-30,A study of coherence based measure of quantumness in (non) Markovian channels,"We make a detailed analysis of quantumness for various quantum noise
channels, both Markovian and non-Markovian. The noise channels considered
include dephasing channels like random telegraph noise, non-Markovian dephasing
and phase damping, as well as the non-dephasing channels such as generalized
amplitude damping and Unruh channels. We make use of a recently introduced
witness for quantumness based on the square $l_1$ norm of coherence. It is
found that the increase in the degree of non-Markovianity increases the
quantumness of the channel.",1905.12872v1
2019-05-30,Stabilization for vibrating plate with singular structural damping,"We consider the dynamic elasticity equation, modeled by the Euler-Bernoulli
plate equation, with a locally distributed singular structural (or viscoelastic
) damping in a boundary domain. Using a frequency domain method combined, based
on the Burq's result, combined with an estimate of Carleman type we provide
precise decay estimate showing that the energy of the system decays
logarithmically as the type goes to the infinity.",1905.13089v1
2020-07-08,The interplay of critical regularity of nonlinearities in a weakly coupled system of semi-linear damped wave equations,"We would like to study a weakly coupled system of semi-linear classical
damped wave equations with moduli of continuity in nonlinearities whose powers
belong to the critical curve in the $p-q$ plane. The main goal of this paper is
to find out the sharp conditions of these moduli of continuity which classify
between global (in time) existence of small data solutions and finite time
blow-up of solutions.",2007.04157v1
2020-07-09,Semi-uniform stability of operator semigroups and energy decay of damped waves,"Only in the last fifteen years or so has the notion of semi-uniform
stability, which lies between exponential stability and strong stability,
become part of the asymptotic theory of $C_0$-semigroups. It now lies at the
very heart of modern semigroup theory. After briefly reviewing the notions of
exponential and strong stability, we present an overview of some of the best
known (and often optimal) abstract results on semi-uniform stability. We go on
to indicate briefly how these results can be applied to obtain (sometimes
optimal) rates of energy decay for certain damped second-order Cauchy problems.",2007.04711v1
2020-07-10,Quasi-periodic travelling waves for a class of damped beams on rectangular tori,"This article concerns a class of beam equations with damping on rectangular
tori. When the generators satisfy certain relationship, by excluding some value
of two model parameters, we prove that such models admit small amplitude
quasi-periodic travelling wave solutions with two frequencies, which are
continuations of two rotating wave solutions with one frequency. This result
holds not only for an isotropic torus, but also for an anisotropic torus. The
proof is mainly based on a Lyapunov--Schmidt reduction together with the
implicit function theorem.",2007.05154v1
2020-07-24,A Framework to Control Inter-Area Oscillations with Local Measurement,"Inter-area oscillations in power system limit of power transfer capability
though tie-lines. For stable operation, wide-area power system stabilizers are
deployed to provide sufficient damping. However, as the feedback is through a
communication network, it brings challenges such as additional communication
layer and cybersecurity issues. To address this, a framework for synthesizing
remote signal from local measurement as feedback in the wide-area power system
stabilizer is proposed. The remote signal is synthesized using different
variants of observers in a case study of two-area benchmark system. The
proposed framework can improve the damping of inter-area oscillations for
static output feedback controller. The presented framework should help to
design attack-resilient controller design in smart grid.",2007.12426v1
2020-07-24,Convergence Rates of Inertial Primal-Dual Dynamical Methods for Separable Convex Optimization Problems,"In this paper, we propose a second-order continuous primal-dual dynamical
system with time-dependent positive damping terms for a separable convex
optimization problem with linear equality constraints. By the Lyapunov function
approach, we investigate asymptotic properties of the proposed dynamical system
as the time $t\to+\infty$. The convergence rates are derived for different
choices of the damping coefficients. We also show that the obtained results are
robust under external perturbations.",2007.12428v1
2010-05-21,Quantization of the Damped Harmonic Oscillator Revisited,"We return to the description of the damped harmonic oscillator by means of a
closed quantum theory with a general assessment of previous works, in
particular the Bateman-Caldirola-Kanai model and a new model recently proposed
by one of the authors. We show the local equivalence between the two models and
argue that latter has better high energy behavior and is naturally connected to
existing open-quantum-systems approaches.",1005.4096v1
2013-08-30,"A conservative, skew-symmetric Finite Difference Scheme for the compressible Navier--Stokes Equations","We present a fully conservative, skew-symmetric finite difference scheme on
transformed grids. The skew-symmetry preserves the kinetic energy by first
principles, simultaneously avoiding a central instability mechanism and
numerical damping. In contrast to other skew-symmetric schemes no special
averaging procedures are needed. Instead, the scheme builds purely on
point-wise operations and derivatives. Any explicit and central derivative can
be used, permitting high order and great freedom to optimize the scheme
otherwise. This also allows the simple adaption of existing finite difference
schemes to improve their stability and damping properties.",1308.6672v1
2016-11-01,On the penalty stabilization mechanism for upwind discontinuous Galerkin formulations of first order hyperbolic systems,"Penalty fluxes are dissipative numerical fluxes for high order discontinuous
Galerkin (DG) methods which depend on a penalization parameter. We investigate
the dependence of the spectra of high order DG discretizations on this
parameter, and show that as its value increases, the spectra of the DG
discretization splits into two disjoint sets of eigenvalues. One set converges
to the eigenvalues of a conforming discretization, while the other set
corresponds to spurious eigenvalues which are damped proportionally to the
parameter. Numerical experiments also demonstrate that undamped spurious modes
present in both in the limit of zero and large penalization parameters are
damped for moderate values of the upwind parameter.",1611.00102v2
2016-11-26,Landau damping of surface plasmons in metal nanostructures,"We develop a quantum-mechanical theory for Landau damping of surface plasmons
in metal nanostructures larger that the characteristic length for nonlocal
effects. We show that the electron surface scattering, which facilitates
plasmon decay in small nanostructures, can be incorporated into the metal
dielectric function on par with phonon and impurity scattering. The derived
surface scattering rate is determined by the plasmon local field polarization
relative to the metal-dielectric interface and is highly sensitive to the
system geometry. We illustrate our model by providing analytical results for
surface scattering rate in some common shape nanostructures.",1611.08670v3
2016-11-27,Convergence in probability of an ergodic and conformal multi-symplectic numerical scheme for a damped stochastic NLS equation,"In this paper, we investigate the convergence order in probability of a novel
ergodic numerical scheme for damped stochastic nonlinear Schr\""{o}dinger
equation with an additive noise. Theoretical analysis shows that our scheme is
of order one in probability under appropriate assumptions for the initial value
and noise. Meanwhile, we show that our scheme possesses the unique ergodicity
and preserves the discrete conformal multi-symplectic conservation law.
Numerical experiments are given to show the longtime behavior of the discrete
charge and the time average of the numerical solution, and to test the
convergence order, which verify our theoretical results.",1611.08778v1
2017-01-30,Energy Transport Property of Charged Particles with Time-Dependent Damping Force via Manifold-Based Analysis Approach,"This paper deals with the energy transport properties of charged particles
with time-dependent damping force. Based on the proposed nonlinear
dimensionless mapping,the stability and dynamical evolution of the particle
system is analyzed with the help of manifold-based analysis approach.It has
been found that the particle system possesses two types of energy asymptotic
behaviors. More significantly, the underlying mechanism of an ""energy barrier""
is uncovered,i.e., one generalized invariant spanning curve emerges in the
dissipative particle system. These results will be useful to enrich the energy
transport behavior knowledge of the particle system.",1701.08762v1
2017-04-09,Controllability of the Strongly Damped Impulsive Semilinear Wave Equation with Memory and Delay,"This article is devoted to study the interior approximated controllability of
the strongly damped semilinear wave equation with memory, impulses and delay
terms. The problem is challenging since the state equation contains memory and
impulsive terms yielding to potential unbounded control sequences steering the
system to a neighborhood of the final state, thus fixed point theorems cannot
be used directly. As alternative, the A.E Bashirov and et al. techniques are
applied and together with the delay allow the control solution to be directed
to fixed curve in a short time interval and achieve our result.",1704.02561v1
2017-04-12,Damping parametric instabilities in future gravitational wave detectors by means of electrostatic actuators,"It has been suggested that the next generation of interferometric
gravitational wave detectors may observe spontaneously excited parametric
oscillatory instabilities. We present a method of actively suppressing any such
instability through application of electrostatic forces to the interferometers'
test masses. Using numerical methods we quantify the actuation force required
to damp candidate instabilities and find that such forces are readily
achievable. Our predictions are subsequently verified experimentally using
prototype Advanced LIGO hardware, conclusively demonstrating the effectiveness
of our approach.",1704.03587v1
2017-04-28,Cross-damping effects in 1S-3S spectroscopy of hydrogen and deuterium,"We calculate the cross-damping frequency shift of a laser-induced two-photon
transition monitored through decay fluorescence, by adapting the analogy with
Raman scattering developed by Amaro et al. [P. Amaro et al., PRA 92, 022514
(2015)]. We apply this method to estimate the frequency shift of the 1S-3S
transition in hydrogen and deuterium. Taking into account our experimental
conditions, we find a frequency shift of less than 1 kHz, that is smaller than
our current statistical uncertainty.",1704.09003v1
2018-05-08,Optomechanical damping as the origin of sideband asymmetry,"Sideband asymmetry in cavity optomechanics has been explained by particle
creation and annihilation processes, which bestow an amplitude proportional to
'n+1' and 'n' excitations to each of the respective sidebands. We discuss the
issues with this as well as other interpretations, such as quantum backaction
and noise interference, and show that the asymmetry is due to the
optomechanical damping caused by the probe and the cooling lasers instead.",1805.02952v4
2018-05-11,On the asymptotic stability of stratified solutions for the 2D Boussinesq equations with a velocity damping term,"We consider the 2D Boussinesq equations with a velocity damping term in a
strip $\mathbb{T}\times[-1,1]$, with impermeable walls. In this physical
scenario, where the \textit{Boussinesq approximation} is accurate when
density/temperature variations are small, our main result is the asymptotic
stability for a specific type of perturbations of a stratified solution. To
prove this result, we use a suitably weighted energy space combined with linear
decay, Duhamel's formula and ""bootstrap"" arguments.",1805.05179v2
2009-12-15,Distillability sudden death in qutrit-qutrit systems under amplitude damping,"Recently it has been discovered that certain two-qutrit entangled states
interacting with global and/or multi-local decoherence undergo distillability
sudden death (DSD). We investigate this phenomenon for qutrit-qutrit systems
interacting with statistically independent zero-temperature reservoirs. We show
that certain initially prepared free-entangled states become bound-entangled in
a finite time due to the action of Markovian dissipative environment. Moreover,
in contrast with local dephasing, simple local unitary transformations can
completely avoid distillability sudden death under amplitude damping.",0912.2868v1
2009-12-15,Global Controllability of Multidimensional Rigid Body by Few Torques,"We study global controllability of 'rotating' multidimensional rigid body
(MRB) controlled by application of few torques. Study by methods of geometric
control requires analysis of algebraic structure introduced by the quadratic
term of Euler-Frahm equation. We discuss problems, which arise in the course of
this analysis, and establish several global controllability criteria for damped
and non damped cases.",0912.2900v1
2011-11-01,Damping of tensor modes in inflation,"We discuss the damping of tensor modes due to anisotropic stress in
inflation. The effect is negligible in standard inflation and may be
significantly large in inflation models that involve drastic production of
free-streaming particles.",1111.0295v3
2011-11-04,Global uniform asymptotic stabilization and k-exponential trajectory tracking of underactuated surface ships with non-diagonal inertia/damping matrices,"In this work, we investigate the state stabilization and trajectory tracking
problems of underactuated surface ships with full state model of having
non-diagonal inertia and damping matrices. By combining the novel state
transformations, the direct Lyapunov approach, and the nonlinear time-varying
tools, the stabilization and the trajectory tracking controllers are developed
respectively guaranteeing global uniform asymptotic convergence of the state to
the desired set point and global exponential convergence to the desired
reference trajectory via mild persistent exciting conditions. Simulation
examples are given to illustrate the effectiveness of the proposed control
schemes.",1111.1029v1
2011-11-08,The entropy of large black holes in loop quantum gravity: A combinatorics/analysis approach,"The issue of a possible damping of the entropy periodicity for large black
holes in Loop Quantum Gravity is highly debated. Using a combinatorics/analysis
approach, we give strong arguments in favor of this damping, at least for
prescriptions where the projection constraint is not fully implemented. This
means that black holes in loop gravity exhibit an asymptotic Bekenstein-Hawking
behavior, provided that a consistent choice of the Immirzi constant is made.",1111.1975v1
2011-11-15,Finite Size Effects of the Surface States in a Lattice Model of Topological Insulator,"Energy gap and wave function in thin films of topological insulator is
studied, based on tight--binding model. It is revealed that thickness
dependence of the magnitude of energy gap is composed of damping and
oscillation. The damped behavior originates from the presence of gapless
surface Dirac cone in the infinite thickness limit. On the other hand, the
oscillatory behavior stems from electronic properties in the thin thickness
limit.",1111.3528v2
2011-11-23,Pumping the eccentricity of exoplanets by tidal effect,"Planets close to their host stars are believed to undergo significant tidal
interactions, leading to a progressive damping of the orbital eccentricity.
Here we show that, when the orbit of the planet is excited by an outer
companion, tidal effects combined with gravitational interactions may give rise
to a secular increasing drift on the eccentricity. As long as this secular
drift counterbalances the damping effect, the eccentricity can increase to high
values. This mechanism may explain why some of the moderate close-in exoplanets
are observed with substantial eccentricity values.",1111.5486v1
2011-11-30,Shear viscosity and damping of collective modes in a two-dimensional Fermi gas,"We compute the shear viscosity of a two dimensional Fermi gas interacting via
a short range potential with scattering length $a_{2d}$ in kinetic theory. We
find that kinetic theory predicts that the shear viscosity to entropy density
ratio of a strongly interacting two dimensional gas is comparable to that of
the three dimensional unitary gas. We use our results to compute the damping of
collective modes in a trapped Fermi gas, and compare to experimental data
recently obtained in E. Vogt et al., arXiv:1111.1173.",1111.7242v2
2011-12-31,Stability of cnoidal waves in the parametrically driven nonlinear Schrödinger equation,"The parametrically driven, damped nonlinear Schr\""odinger equation has two
cn- and two dn-wave solutions. We show that one pair of the cn and dn solutions
is unstable for any combination of the driver's strength, dissipation
coefficient and spatial period of the wave; this instability is against
periodic perturbations. The second dn-wave solution is shown to be unstable
against antiperiodic perturbations --- in a certain region of the parameter
space. We also consider quasiperiodic perturbations with long modulation
wavelength, in the limit where the driving strength is only weakly exceeding
the damping coefficient.",1201.0263v1
2012-01-03,Dynamics of DNA Bubble in Viscous Medium,"The damping effect to the DNA bubble is investigated within the
Peyrard-Bishop model. In the continuum limit, the dynamics of the bubble of DNA
is described by the damped nonlinear Schrodinger equation and studied by means
of variational method. It is shown that the propagation of solitary wave
pattern is not vanishing in a non-viscous system. Inversely, the solitary wave
vanishes soon as the viscous force is introduced.",1201.0689v2
2012-01-18,Magnetohydrodynamic Waves in Partially Ionized Prominence Plasmas,"Prominences or filaments are cool clouds of partially ionized plasma living
in the solar corona. Ground- and space-based observations have confirmed the
presence of oscillatory motions in prominences and they have been interpreted
in terms of magnetohydrodynamic (MHD) waves. Existing observational evidence
points out that these oscillatory motions are damped in short spatial and
temporal scales by some still not well known physical mechanism(s). Since
prominences are partially ionized plasmas, a potential mechanism able to damp
these oscillations could be ion-neutral collisions. Here, we will review the
work done on the effects of partial ionization on MHD waves in prominence
plasmas.",1201.3752v1
2012-01-26,Inhomogeneous spin diffusion in traps with cold atoms,"The spin diffusion and damped oscillations are studied in the collision of
two spin polarized clouds of cold atoms with resonant interactions. The strong
density dependence of the diffusion coefficient leads to inhomogeneous spin
diffusion that changes from central to surface spin flow as the temperature
increases. The inhomogeneity and the smaller finite trap size significantly
reduce the spin diffusion rate at low temperatures. The resulting spin
diffusion rates, spin drag and initial damped oscillations are compatible with
measurements at low to high temperatures for resonant attractive interactions
but are incompatible with a metastable ferromagnetic phase.",1201.5526v2
2012-01-30,Volatility-dependent damping of evaporation-driven Bénard-Marangoni instability,"The interface between a pure liquid and its vapor is usually close to
saturation temperature, hence strongly hindering any thermocapillary flow. In
contrast, when the gas phase contains an inert gas such as air,
surface-tension-driven convection is easily observed. We here reconcile these
two facts by studying the corresponding crossover experimentally, as a function
of a new dimensionless number quantifying the degree of damping of interfacial
temperature fluctuations. Critical conditions are in convincing agreement with
a simple nonlocal one-sided model, in quite a range of evaporation rates.",1201.6334v1
2012-04-03,Modification in Silling's Peridynamic Formulation of Elasticity Theory for Discontinuities and Long-Range Forces,"We suggest modified version of Silling's peridynamic equation of motion
within the framework of Silling's peridynamics formulation (J. Mech. Phys.
Solids {\bf 48}, pp.175-209, 2000) of elasticity theory. The modified equation
contains an additional damping force term. This term can eliminate artificial
oscillations in displacement field at large values of time as predicted by
Silling's peridynamic equation.",1204.0612v2
2012-04-06,Experimental signatures of the quantum-classical transition in a nanomechanical oscillator modeled as a damped driven double-well problem,"We demonstrate robust and reliable signatures for the transition from quantum
to classical behavior in the position probability distribution of a damped
double-well system using the Qunatum State Diffusion approach to open quantum
systems. We argue that these signatures are within experimental reach, for
example in a doubly-clamped nanomechanical beam.",1204.1397v1
2013-09-09,Classical and quantum capacities of a fully correlated amplitude damping channel,"We study information transmission over a fully correlated amplitude damping
channel acting on two qubits. We derive the single-shot classical channel
capacity and show that entanglement is needed to achieve the channel best
performance. We discuss the degradability properties of the channel and
evaluate the quantum capacity for any value of the noise parameter. We finally
compute the entanglement-assisted classical channel capacity.",1309.2219v3
2013-09-13,Polarization hydrodynamics in a one-dimensional polariton condensate,"We study the hydrodynamics of a nonresonantly-pumped polariton condensate in
a quasi-one-dimensional quantum wire taking into account the spin degree of
freedom. We clarify the relevance of the Landau criterion for superfluidity in
this dissipative two-component system. Two Cherenkov-like critical velocities
are identified corresponding to the opening of different channels of radiation:
one of (damped) density fluctuations and another of (weakly damped)
polarization fluctuations. We determine the drag force exerted onto an external
obstacle and propose experimentally measurable consequences of the specific
features of the fluctuations of polarization.",1309.3494v1
2013-09-26,Imperfect geometric control and overdamping for the damped wave equation,"We consider the damped wave equation on a manifold with imperfect geometric
control. We show the sub-exponential energy decay estimate in
\cite{Chr-NC-erratum} is optimal in the case of one hyperbolic periodic
geodesic. We show if the equation is overdamped, then the energy decays
exponentially. Finally we show if the equation is overdamped but geometric
control fails for one hyperbolic periodic geodesic, then nevertheless the
energy decays exponentially.",1309.6967v1
2014-05-01,On the collapse of trial solutions for a damped-driven non-linear Schrödinger equation,"We consider the focusing 2D non-linear Schr\""odinger equation, perturbed by a
damping term, and driven by multiplicative noise. We show that a physically
motivated trial solution does not collapse for any admissible initial condition
although the exponent of the non-linearity is critical. Our method is based on
the construction of a global solution to a singular stochastic Hamiltonian
system used to connect trial solution and Schr\""odinger equation.",1405.0151v3
2014-05-02,Dynamic phase diagram of dc-pumped magnon condensates,"We study the effects of nonlinear dynamics and damping by phonons on a system
of interacting electronically pumped magnons in a ferromagnet. The nonlinear
effects are crucial for constructing the dynamic phase diagram, which describes
how ""swasing"" and Bose-Einstein condensation emerge out of the
quasiequilibrated thermal cloud of magnons. We analyze the system in the
presence of magnon damping and interactions, demonstrating the continuous onset
of stable condensates as well as hysteretic transitions.",1405.0522v1
2014-05-05,Finite time extinction for nonlinear Schrodinger equation in 1D and 2D,"We consider a nonlinear Schrodinger equation with power nonlinearity, either
on a compact manifold without boundary, or on the whole space in the presence
of harmonic confinement, in space dimension one and two. Up to introducing an
extra superlinear damping to prevent finite time blow up, we show that the
presence of a sublinear damping always leads to finite time extinction of the
solution in 1D, and that the same phenomenon is present in the case of small
mass initial data in 2D.",1405.0995v1
2014-05-16,Investigation of Power-Law Damping/Dissipative Forces,"The properties of a one space-dimension, one particle dynamical system under
the influence of a purely dissipative force are investigated. Assuming this
force depends only on the velocity, it is demonstrated, in contrast to the case
of linear damping, that there exist dissipative forces for which the particle
\textquotedblleft stops"" in a finite time. It is also shown, by an explicit
example, that other dissipative forces exist such that they produce dynamics in
which the particle achieves zero velocity only after an infinite distance has
been traveled. Possible applications of these results to more complex
situations are discussed.",1405.4062v1
2014-06-02,"Nonlinear coupler operating on Werner-like states - entanglement creation, its enhancement and preservation","We discuss a model of two nonlinear Kerr-like oscillators, mutually coupled
and excited by parametric process. We show that the system's evolution,
starting from Werner-like states, remains closed within a small set of two-mode
n-photon states the system, and pure two-qubit entangled state can be
generated. For some initial Werner-like states delayed entanglement generation
can be observed. We investigate the influence of two damping mechanisms on the
system's evolution. We show that for the both cases, the entanglement can
survive despite the presence of damping, and the effects of sudden entanglement
death and its rebirth can appear in the system.",1406.0414v1
2014-06-10,A determining form for the damped driven Nonlinear Schrödinger Equation- Fourier modes case,"In this paper we show that the global attractor of the 1D damped, driven,
nonlinear Schr\""odinger equation (NLS) is embedded in the long-time dynamics of
a determining form. The determining form is an ordinary differential equation
in a space of trajectories $X=C_b^1(\mathbb{R}, P_mH^2)$ where $P_m$ is the
$L^2$-projector onto the span of the first $m$ Fourier modes. There is a
one-to-one identification with the trajectories in the global attractor of the
NLS and the steady states of the determining form. We also give an improved
estimate for the number of the determining modes.",1406.2626v1
2015-12-03,Evidence for the role of normal-state electrons in nanoelectromechanical damping mechanisms at very low temperatures,"We report on experiments performed at low temperatures on aluminum covered
silicon nanoelectromechanical resonators. The substantial difference observed
between the mechanical dissipation in the normal and superconducting states
measured within the same device unambiguously demonstrates the importance of
normal-state electrons in the damping mechanism. The dissipative component
becomes vanishingly small at very low temperatures in the superconducting
state, leading to exceptional values for the quality factor of such small
silicon structures. A critical discussion is given within the framework of the
standard tunneling model.",1512.01036v1
2015-12-31,Nonlinear stochastic evolution equations of second order with damping,"Convergence of a full discretization of a second order stochastic evolution
equation with nonlinear damping is shown and thus existence of a solution is
established. The discretization scheme combines an implicit time stepping
scheme with an internal approximation. Uniqueness is proved as well.",1512.09260v2
2016-05-15,Propagation of Thermally Induced Magnonic Spin Currents,"The propagation of magnons in temperature gradients is investigated within
the framework of an atomistic spin model with the stochastic
Landau-Lifshitz-Gilbert equation as underlying equation of motion. We analyze
the magnon accumulation, the magnon temperature profile as well as the
propagation length of the excited magnons. The frequency distribution of the
generated magnons is investigated in order to derive an expression for the
influence of the anisotropy and the damping parameter on the magnon propagation
length. For soft ferromagnetic insulators with low damping a propagation length
in the range of some $\mu$m can be expected for exchange driven magnons.",1605.04543v1
2016-05-24,Non-existence for fractionally damped fractional differential problems,"In this paper, we are concerned with a fractional differential inequality
containing a lower order fractional derivative and a polynomial source term in
the right hand side. A non-existence of non-trivial global solutions result is
proved in an appropriate space by means of the test-function method. The range
of blow up is found to depend only on the lower order derivative. This is in
line with the well-known fact for an internally weakly damped wave equation
that solutions will converge to solutions of the parabolic part.",1605.07432v1
2016-05-31,On the Benjamin-Bona-Mahony equation with a localized damping,"We introduce several mechanisms to dissipate the energy in the
Benjamin-Bona-Mahony (BBM) equation. We consider either a distributed
(localized) feedback law, or a boundary feedback law. In each case, we prove
the global wellposedness of the system and the convergence towards a solution
of the BBM equation which is null on a band. If the Unique Continuation
Property holds for the BBM equation, this implies that the origin is
asymp-totically stable for the damped BBM equation.",1605.09574v1
2016-08-01,Landau-Khalatnikov phonon damping in strongly interacting Fermi gases,"We derive the phonon damping rate due to the four-phonon Landau-Khalatnikov
process in low temperature strongly interacting Fermi gases using quantum
hydrodynamics, correcting and extending the original calculation of Landau and
Khalatnikov [ZhETF, 19 (1949) 637]. Our predictions can be tested in
state-of-the-art experiments with cold atomic gases in the collisionless
regime.",1608.00402v3
2016-08-17,New mechanism of acceleration of particles by stellar black holes,"In this paper we study efficiency of particle acceleration in the
magnetospheres of stellar mass black holes. For this purpose we consider the
linearized set of the Euler equation, continuity equation and Poisson equation
respectively. After introducing the varying relativistic centrifugal force, we
show that the charge separation undergoes the parametric instability, leading
to generation of centrifugally excited Langmuir waves. It is shown that these
waves, via the Langmuir collapse damp by means of the Landau damping, as a
result energy transfers to particles accelerating them to energies of the order
of $10^{16}$eV.",1608.04889v1
2016-12-27,Wiggler for CESR operation at 2 GeV,"For low energy operation strategy we advocate utilization of many short
wigglers in contrast with single long wiggler. This allows begin to operate
very naturally with few strong field wigglers giving necessary damping time on
expense of energy spread. By adding more and more wigglers in the ring, as
these wigglers are manufactured and tuned, the field in the wigglers will be
decreased, keeping necessary damping. This strategy allows the mostly effective
operation of CESR with minimum down time. This also gives flexibility in
operation in wider energy scale without non-reversible modifications.",1612.09227v1
2017-06-26,Weighted energy estimates for wave equation with space-dependent damping term for slowly decaying initial data,"This paper is concerned with weighted energy estimates for solutions to wave
equation $\partial_t^2u-\Delta u + a(x)\partial_tu=0$ with space-dependent
damping term $a(x)=|x|^{-\alpha}$ $(\alpha\in [0,1))$ in an exterior domain
$\Omega$ having a smooth boundary. The main result asserts that the weighted
energy estimates with weight function like polymonials are given and these
decay rate are almost sharp, even when the initial data do not have compact
support in $\Omega$. The crucial idea is to use special solution of $\partial_t
u=|x|^{\alpha}\Delta u$ including Kummer's confluent hypergeometric functions.",1706.08311v1
2017-10-13,$L^2$ asymptotic profiles of solutions to linear damped wave equations,"In this paper we obtain higher order asymptotic profilles of solutions to the
Cauchy problem of the linear damped wave equation in $\textbf{R}^n$
\begin{equation*} u_{tt}-\Delta u+u_t=0, \qquad u(0,x)=u_0(x), \quad
u_t(0,x)=u_1(x), \end{equation*} where $n\in\textbf{N}$ and $u_0$, $u_1\in
L^2(\textbf{R}^n)$. Established hyperbolic part of asymptotic expansion seems
to be new in the sense that the order of the expansion of the hyperbolic part
depends on the spatial dimension.",1710.04870v1
2017-12-13,Sub-logistic source can prevent blow-up in the 2D minimal Keller-Segel chemotaxis system,"It is well-known that the Neumann initial-boundary value problem for the
minimal-chemotaxis-logistic system in a 2D bounded smooth domain has no blow-up
for any choice of parameters. Here, for a large class of kinetic terms
including sub-logistic sources, we show that the corresponding 2D Neumann
initial-boundary value problems do not possess any blow-up. This illustrates a
new phenomenon that even a class of sub-logistic sources can prevent blow-up
for the 2D problem, indicating that logistic damping is not the weakest damping
to guarantee uniform-in-time boundedness for the 2D minimal Keller-Segel
chemotaxis model.",1712.04739v1
2017-12-16,Convergence to Equilibrium in Wasserstein distance for damped Euler equations with interaction forces,"We develop tools to construct Lyapunov functionals on the space of
probability measures in order to investigate the convergence to global
equilibrium of a damped Euler system under the influence of external and
interaction potential forces with respect to the 2-Wasserstein distance. We
also discuss the overdamped limit to a nonlocal equation used in the modelling
of granular media with respect to the 2-Wasserstein distance, and provide
rigorous proofs for particular examples in one spatial dimension.",1712.05923v2
2017-12-27,Normal-mode-based analysis of electron plasma waves with second-order Hermitian formalism,"The classic problem of the dynamic evolution of Langmuir electron waves in a
collisionless plasma and their Landau damping is cast as a second-order,
self-adjoint problem with a continuum spectrum of real and positive squared
frequencies. The corresponding complete basis of singular normal modes is
obtained, along with their orthogonality relation. This yields easily the
general expression of the time-reversal-invariant solution for any
initial-value problem. An example is given for a specific initial condition
that illustrates the Landau damping of the macroscopic moments of the
perturbation.",1712.09682v1
2018-01-19,Discontinuous energy shaping control of the Chaplygin sleigh,"In this paper we present an energy shaping control law for set-point
regulation of the Chaplygin sleigh. It is well known that nonholonomic
mechanical systems cannot be asymptotically stabilised using smooth control
laws as they do no satisfy Brockett's necessary condition for smooth
stabilisation. Here, we propose a discontinuous control law that can be seen as
a potential energy shaping and damping injection controller. The proposed
controller is shown to be robust against the parameters of both the inertia
matrix and the damping structure of the open-loop system.",1801.06278v1
2018-01-19,Robust integral action of port-Hamiltonian systems,"Interconnection and damping assignment, passivity-based control (IDA-PBC) has
proven to be a successful control technique for the stabilisation of many
nonlinear systems. In this paper, we propose a method to robustify a system
which has been stabilised using IDA-PBC with respect to constant, matched
disturbances via the addition of integral action. The proposed controller
extends previous work on the topic by being robust against the damping of the
system, a quantity which may not be known in many applications.",1801.06279v1
2018-01-19,A study of Landau damping with random initial inputs,"For the Vlasov-Poisson equation with random uncertain initial data, we prove
that the Landau damping solution given by the deterministic counterpart
(Caglioti and Maffei, {\it J. Stat. Phys.}, 92:301-323, 1998) depends smoothly
on the random variable if the time asymptotic profile does, under the
smoothness and smallness assumptions similar to the deterministic case. The
main idea is to generalize the deterministic contraction argument to more
complicated function spaces to estimate derivatives in space, velocity and
random variables. This result suggests that the random space regularity can
persist in long-time even in time-reversible nonlinear kinetic equations.",1801.06304v1
2018-01-31,Smoluchowski-Kramers approximation for the damped stochastic wave equation with multiplicative noise in any spatial dimension,"We show that the solutions to the damped stochastic wave equation converge
pathwise to the solution of a stochastic heat equation. This is called the
Smoluchowski-Kramers approximation. Cerrai and Freidlin have previously
demonstrated that this result holds in the cases where the system is exposed to
additive noise in any spatial dimension or when the system is exposed to
multiplicative noise and the spatial dimension is one. The current paper proves
that the Smoluchowski-Kramers approximation is valid in any spatial dimension
when the system is exposed to multiplicative noise.",1801.10538v1
2018-09-17,Global existence for weakly coupled systems of semi-linear structurally damped $σ$-evolution models with different power nonlinearities,"In this paper, we study the Cauchy problems for weakly coupled systems of
semi-linear structurally damped $\sigma$-evolution models with different power
nonlinearities. By assuming additional $L^m$ regularity on the initial data,
with $m \in [1,2)$, we use $(L^m \cap L^2)- L^2$ and $L^2- L^2$ estimates for
solutions to the corresponding linear Cauchy problems to prove the global (in
time) existence of small data Sobolev solutions to the weakly coupled systems
of semi-linear models from suitable function spaces.",1809.06744v2
2018-09-25,On the energy decay rates for the 1D damped fractional Klein-Gordon equation,"We consider the fractional Klein-Gordon equation in one spatial dimension,
subjected to a damping coefficient, which is non-trivial and periodic, or more
generally strictly positive on a periodic set. We show that the energy of the
solution decays at the polynomial rate $O(t^{-\frac{s}{4-2s}})$ for $0< s<2 $
and at some exponential rate when $s\geq 2$. Our approach is based on the
asymptotic theory of $C_0$ semigroups in which one can relate the decay rate of
the energy in terms of the resolvent growth of the semigroup generator. The
main technical result is a new observability estimate for the fractional
Laplacian, which may be of independent interest.",1809.09531v1
2018-10-15,Global well-posedness in the critical Besov spaces for the incompressible Oldroyd-B model without damping mechanism,"We prove the global well-posedness in the critical Besov spaces for the
incompressible Oldroyd-B model without damping mechanism on the stress tensor
in $\mathbb{R}^d$ for the small initial data. Our proof is based on the
observation that the behaviors of Green's matrix to the system of
$\big(u,(-\Delta)^{-\frac12}\mathbb{P}\nabla\cdot\tau\big)$ as well as the
effects of $\tau$ change from the low frequencies to the high frequencies and
the construction of the appropriate energies in different frequencies.",1810.06171v1
2018-10-18,Global solutions to the $n$-dimensional incompressible Oldroyd-B model without damping mechanism,"The present work is dedicated to the global solutions to the incompressible
Oldroyd-B model without damping on the stress tensor in $\mathbb{R}^n(n=2,3)$.
This result allows to construct global solutions for a class of highly
oscillating initial velocity. The proof uses the special structure of the
system. Moreover, our theorem extends the previous result by Zhu [19] and
covers the recent result by Chen and Hao [4].",1810.08048v3
2018-10-30,Global well-posedness for nonlinear wave equations with supercritical source and damping terms,"We prove the global well-posedness of weak solutions for nonlinear wave
equations with supercritical source and damping terms on a three-dimensional
torus $\mathbb T^3$ of the prototype \begin{align*} &u_{tt}-\Delta
u+|u_t|^{m-1}u_t=|u|^{p-1}u, \;\; (x,t) \in \mathbb T^3 \times \mathbb R^+ ;
\notag\\ &u(0)=u_0 \in H^1(\mathbb T^3)\cap L^{m+1}(\mathbb T^3), \;\;
u_t(0)=u_1\in L^2(\mathbb T^3), \end{align*} where $1\leq p\leq \min\{
\frac{2}{3} m + \frac{5}{3} , m \}$. Notably, $p$ is allowed to be larger than
$6$.",1810.12476v1
2019-06-12,A no-go result for the quantum damped harmonic oscillator,"In this letter we show that it is not possible to set up a canonical
quantization for the damped harmonic oscillator using the Bateman lagrangian.
In particular, we prove that no square integrable vacuum exists for the {\em
natural} ladder operators of the system, and that the only vacua can be found
as distributions. This implies that the procedure proposed by some authors is
only formally correct, and requires a much deeper analysis to be made rigorous.",1906.05121v2
2019-06-26,Mismatched Estimation of Polynomially Damped Signals,"In this work, we consider the problem of estimating the parameters of
polynomially damped sinusoidal signals, commonly encountered in, for instance,
spectroscopy. Generally, finding the parameter values of such signals
constitutes a high-dimensional problem, often further complicated by not
knowing the number of signal components or their specific signal structures. In
order to alleviate the computational burden, we herein propose a mismatched
estimation procedure using simplified, approximate signal models. Despite the
approximation, we show that such a procedure is expected to yield predictable
results, allowing for statistically and computationally efficient estimates of
the signal parameters.",1906.11113v1
2019-06-27,Temperature-Dependent Lifetimes of Low-Frequency Adsorbate Modes from Non-Equilibrium Molecular Dynamics Simulations,"We present calculations on the damping of a low-frequency adsorbate mode on a
metal surface, namely the frustrated translation of Na on Cu(100). For the
first time, vibrational lifetimes of excited adlayers are extracted from
non-equilibrium molecular dynamics calculations accounting for both the
phononic and the electronic dissipation channels. The relative contributions of
the two damping mechanisms, which we show to be additive, are found to disagree
with textbook predictions. A simple model based on separable harmonic and
anharmonic contributions is able to semi-quantitatively reproduce the
temperature dependence of the computed lifetimes.",1906.11776v1
2019-07-10,Formal expansions in stochastic model for wave turbulence 1: kinetic limit,"We consider the damped/driver (modified) cubic NLS equation on a large torus
with a properly scaled forcing and dissipation, and decompose its solutions to
formal series in the amplitude. We study the second order truncation of this
series and prove that when the amplitude goes to zero and the torus' size goes
to infinity the energy spectrum of the truncated solutions becomes close to a
solution of the damped/driven wave kinetic equation. Next we discuss higher
order truncations of the series.",1907.04531v4
2019-07-22,Thresholds for low regularity solutions to wave equations with structural damping,"We study the asymptotic behavior of solutions to wave equations with a
structural damping term \[ u_{tt}-\Delta u+\Delta^2 u_t=0, \qquad
u(0,x)=u_0(x), \,\,\, u_t(0,x)=u_1(x), \] in the whole space. New thresholds
are reported in this paper that indicate which of the diffusion wave property
and the non-diffusive structure dominates in low regularity cases. We develop
to that end the previous author's research in 2019 where they have proposed a
threshold that expresses whether the parabolic-like property or the wave-like
property strongly appears in the solution to some regularity-loss type
dissipative wave equation.",1907.09299v1
2019-09-01,Invariant measures for stochastic damped 2D Euler equations,"We study the two-dimensional Euler equations, damped by a linear term and
driven by an additive noise. The existence of weak solutions has already been
studied; pathwise uniqueness is known for solutions that have vorticity in
$L^\infty$. In this paper, we prove the Markov property and then the existence
of an invariant measure in the space $L^\infty$ by means of a
Krylov-Bogoliubov's type method, working with the weak$\star$ and the bounded
weak$\star$ topologies in $L^\infty$.",1909.00424v2
2019-09-03,A blow-up result for semi-linear structurally damped $σ$-evolution equations,"We would like to prove a blow-up result for semi-linear structurally damped
$\sigma$-evolution equations, where $\sigma \ge 1$ and $\delta\in [0,\sigma)$
are assumed to be any fractional numbers. To deal with the fractional Laplacian
operators $(-\Delta)^\sigma$ and $(-\Delta)^\delta$ as well-known non-local
operators, in general, it seems difficult to apply the standard test function
method directly. For this reason, in this paper we shall construct new test
functions to overcome this difficulty.",1909.01181v1
2019-09-09,Action Functional for a Particle with Damping,"In this brief report we discuss the action functional of a particle with
damping, showing that it can be obtained from the dissipative equation of
motion through a modification which makes the new dissipative equation
invariant for time reversal symmetry. This action functional is exactly the
effective action of Caldeira-Leggett model but, in our approach, it is derived
without the assumption that the particle is weakly coupled to a bath of
infinite harmonic oscillators.",1909.03694v2
2019-09-11,Remark on global existence of solutions to the 1D compressible Euler equation with time-dependent damping,"In this paper, we consider the 1D compressible Euler equation with the
damping coefficient $\lambda/(1+t)^{\mu}$. Under the assumption that $0\leq \mu
<1$ and $\lambda >0$ or $\mu=1$ and $\lambda > 2$, we prove that solutions
exist globally in time, if initial data are small $C^1$ perturbation near
constant states. In particular, we remove the conditions on the limit
$\lim_{|x| \rightarrow \infty} (u (0,x), v (0,x))$, assumed in previous
results.",1909.05683v1
2019-09-11,Equilibrium radiation in a plasma medium with spatial and frequency dispersion,"Examination of equilibrium radiation in plasma media shows that the spectral
energy distribution of such radiation is different from the Planck equilibrium
radiation. Using the approach of quantum electrodynamics the general relation
for the spectral energy density of equilibrium radiation in a system of charged
particles is found. The obtained result takes into account the influence of
plasma on equilibrium radiation through the explicit transverse dielectric
permittivity which takes into account spatial and frequency dispersion, as well
as the finite collisional damping. For the limiting case of an infinitesimal
damping the result coincides with the known expression.",1909.08056v1
2019-10-14,Blow-up of solutions to semilinear strongly damped wave equations with different nonlinear terms in an exterior domain,"In this paper, we consider the initial boundary value problem in an exterior
domain for semilinear strongly damped wave equations with power nonlinear term
of the derivative-type $|u_t|^q$ or the mixed-type $|u|^p+|u_t|^q$, where
$p,q>1$. On one hand, employing the Banach fixed-point theorem we prove local
(in time) existence of mild solutions. On the other hand, under some conditions
for initial data and the exponents of power nonlinear terms, the blow-up
results are derived by applying the test function method.",1910.05981v1
2020-01-29,The long time behavior and the rate of convergence of symplectic convex algorithms obtained via splitting discretizations of inertial damping systems,"In this paper we propose new numerical algorithms in the setting of
unconstrained optimization problems and we study the rate of convergence in the
iterates of the objective function. Furthermore, our algorithms are based upon
splitting and symplectic methods and they preserve the energy properties of the
inherent continuous dynamical system that contains a Hessian perturbation. At
the same time, we show that Nesterov gradient method is equivalent to a
Lie-Trotter splitting applied to a Hessian driven damping system. Finally, some
numerical experiments are presented in order to validate the theoretical
results.",2001.10831v2
2020-02-05,Long-time asymptotics of the one-dimensional damped nonlinear Klein-Gordon equation,"For the one-dimensional nonlinear damped Klein-Gordon equation \[
\partial_{t}^{2}u+2\alpha\partial_{t}u-\partial_{x}^{2}u+u-|u|^{p-1}u=0 \quad
\mbox{on $\mathbb{R}\times\mathbb{R}$,}\] with $\alpha>0$ and $p>2$, we prove
that any global finite energy solution either converges to $0$ or behaves
asymptotically as $t\to \infty$ as the sum of $K\geq 1$ decoupled solitary
waves. In the multi-soliton case $K\geq 2$, the solitary waves have alternate
signs and their distances are of order $\log t$.",2002.01826v1
2020-02-11,Distributional Solutions of the Damped Wave Equation,"This work presents results on solutions of the one-dimensional damped wave
equation, also called telegrapher's equation, when the initial conditions are
general distributions, not only functions. We make a complete deduction of its
fundamental solutions, both for positive and negative times. To obtain them we
use only self-similarity arguments and distributional calculus, making no use
of Fourier or Laplace transforms. We next use these fundamental solutions to
prove both the existence and the uniqueness of solutions to the distributional
initial value problem. As applications we recover the semigroup property for
initial data in classical function spaces and also the probability distribution
function for a certain financial model of evolution of prices.",2002.04249v2
2020-02-13,Description of the wavevector dispersion of surface plasmon-phonon-polaritons,"We reported here the results of the calculations of wavevector dispersion of
oscillations frequencies, $\omega'(k)$, and damping $\omega''(k)$ of the
surface plasmon phonon polaritons (\mbox{SPPhP}) for the heavy-doped GaN
sample. We showed that $\omega'(k)$- dependence consists of the three branches
with the specific anticrossing behavior due to the interaction of surface
plasmon polariton (SPP) with surface phonon polariton(SPhP). The strong
renormalization of the damping $\omega''(k)$ in the vicinity of the
anticrossing region was found. The obtained dispersions of the $\omega'(k)$ and
$\omega''(k)$ were applied for the analytical analysis of exact electrodynamic
simulation of the resonant behavior of the reflectivity spectrum of the n-GaN
grating.",2002.05473v1
2020-04-13,Landau damping for analytic and Gevrey data,"In this paper, we give an elementary proof of the nonlinear Landau damping
for the Vlasov-Poisson system near Penrose stable equilibria on the torus
$\mathbb{T}^d \times \mathbb{R}^d$ that was first obtained by Mouhot and
Villani in \cite{MV} for analytic data and subsequently extended by Bedrossian,
Masmoudi, and Mouhot \cite{BMM} for Gevrey-$\gamma$ data,
$\gamma\in(\frac13,1]$. Our proof relies on simple pointwise resolvent
estimates and a standard nonlinear bootstrap analysis, using an ad-hoc family
of analytic and Gevrey-$\gamma$ norms.",2004.05979v3
2020-04-16,Strichartz estimates for mixed homogeneous surfaces in three dimensions,"We obtain sharp mixed norm Strichartz estimates associated to mixed
homogeneous surfaces in $\mathbb{R}^3$. Both cases with and without a damping
factor are considered. In the case when a damping factor is considered our
results yield a wide generalization of a result of Carbery, Kenig, and Ziesler
[CKZ13]. The approach we use is to first classify all possible singularities
locally, after which one can tackle the problem by appropriately modifying the
methods from the paper of Ginibre and Velo [GV92], and by using the recently
developed methods by Ikromov and M\""uller [IM16].",2004.07751v1
2020-04-17,Critical exponent for semi-linear structurally damped wave equation of derivative type,"Main purpose of this paper is to study the following semi-linear structurally
damped wave equation with nonlinearity of derivative type: $$u_{tt}- \Delta u+
\mu(-\Delta)^{\sigma/2} u_t= |u_t|^p,\quad u(0,x)= u_0(x),\quad
u_t(0,x)=u_1(x),$$ with $\mu>0$, $n\geq1$, $\sigma \in (0,2]$ and $p>1$. In
particular, we are going to prove the non-existence of global weak solutions by
using a new test function and suitable sign assumptions on the initial data in
both the subcritical case and the critical case.",2004.08486v2
2020-04-29,Exponential decay for damped Klein-Gordon equations on asymptotically cylindrical and conic manifolds,"We study the decay of the global energy for the damped Klein-Gordon equation
on non-compact manifolds with finitely many cylindrical and subconic ends up to
bounded perturbation. We prove that under the Geometric Control Condition, the
decay is exponential, and that under the weaker Network Control Condition, the
decay is logarithmic, by developing the global Carleman estimate with multiple
weights.",2004.13894v2
2020-12-15,On the stability of Bresse system with one discontinuous local internal Kelvin-Voigt damping on the axial force,"In this paper, we investigate the stabilization of a linear Bresse system
with one discontinuous local internal viscoelastic damping of Kelvin-Voigt type
acting on the axial force, under fully Dirichlet boundary conditions. First,
using a general criteria of Arendt-Batty, we prove the strong stability of our
system. Finally, using a frequency domain approach combined with the multiplier
method, we prove that the energy of our system decays polynomially with
different rates.",2012.08219v1
2020-12-28,An efficient method for approximating resonance curves of weakly-damped nonlinear mechanical systems,"A method is presented for tracing the locus of a specific peak in the
frequency response under variation of a parameter. It is applicable to
periodic, steady-state vibrations of harmonically forced nonlinear mechanical
systems. It operates in the frequency domain and its central idea is to assume
a constant phase lag between forcing and response. The method is validated for
a two-degree-of-freedom oscillator with cubic spring and a bladed disk with
shroud contact. The method provides superior computational efficiency, but is
limited to weakly-damped systems. Finally, the capability to reveal isolated
solution branches is highlighted.",2012.14458v1
2021-01-16,Convergence of non-autonomous attractors for subquintic weakly damped wave equation,"We study the non-autonomous weakly damped wave equation with subquintic
growth condition on the nonlinearity. Our main focus is the class of
Shatah--Struwe solutions, which satisfy the Strichartz estimates and are
coincide with the class of solutions obtained by the Galerkin method. For this
class we show the existence and smoothness of pullback, uniform, and cocycle
attractors and the relations between them. We also prove that these
non-autonomous attractors converge upper-semicontinuously to the global
attractor for the limit autonomous problem if the time-dependent nonlinearity
tends to time independent function in an appropriate way.",2101.06523v1
2021-01-20,A Damped Newton Algorithm for Generated Jacobian Equations,"Generated Jacobian Equations have been introduced by Trudinger [Disc. cont.
dyn. sys (2014), pp. 1663-1681] as a generalization of Monge-Amp{\`e}re
equations arising in optimal transport. In this paper, we introduce and study a
damped Newton algorithm for solving these equations in the semi-discrete
setting, meaning that one of the two measures involved in the problem is
finitely supported and the other one is absolutely continuous. We also present
a numerical application of this algorithm to the near-field parallel refractor
problem arising in non-imaging problems.",2101.08080v1
2012-05-31,The impact of fill patterns on the fast ion instability in the ILC damping ring,"The ions produced via collisional ionization of the residual gas molecules in
vacuum pipe with the circulating electron beam have deleterious effect on the
beam properties and may become a limiting factor for the machine's performance.
For the electron damping ring of the International Linear Collider (ILC), the
ion instability is noticeable due to the ultra-low beam emittance with many
bunches operation. In this paper, the different beam fill patterns are
investigated and their effects on the fast ion instability are discussed. The
simulations show that the mini train fill patterns can reduce the growth of the
fast ion instability significantly.",1205.6977v1
2017-05-15,Damping self-forces and Asymptotic Symmetries,"Energy conservation in radiating processes requires, at the classical level,
to take into account damping forces on the sources. These forces can be
represented in terms of asymptotic data and lead to charges defined as
integrals over the asymptotic boundary. For scattering processes these charges,
in case of zero radiated energy, are conserved and encode the information about
the sub-leading soft theorems and matching conditions. The QED version of the
self forces is associated with the dependence of the differential cross section
on the infrared resolution scale.",1705.05297v2
2017-05-17,Exact Model Reduction for Damped-Forced Nonlinear Beams: An Infinite-Dimensional Analysis,"We use invariant manifold results on Banach spaces to conclude the existence
of spectral submanifolds (SSMs) in a class of nonlinear, externally forced beam
oscillations. SSMs are the smoothest nonlinear extensions of spectral subspaces
of the linearized beam equation. Reduction of the governing PDE to SSMs
provides an explicit low-dimensional model which captures the correct
asymptotics of the full, infinite-dimensional dynamics. Our approach is general
enough to admit extensions to other types of continuum vibrations. The
model-reduction procedure we employ also gives guidelines for a mathematically
self-consistent modeling of damping in PDEs describing structural vibrations.",1705.06133v1
2017-11-06,Linear inviscid damping and enhanced dissipation for the Kolmogorov flow,"In this paper, we prove the linear inviscid damping and voticity depletion
phenomena for the linearized Euler equations around the Kolmogorov flow. These
results confirm Bouchet and Morita's predictions based on numerical analysis.
By using the wave operator method introduced by Li, Wei and Zhang, we solve
Beck and Wayne's conjecture on the optimal enhanced dissipation rate for the
2-D linearized Navier-Stokes equations around the bar state called Kolmogorov
flow. The same dissipation rate is proved for the Navier-Stokes equations if
the initial velocity is included in a basin of attraction of the Kolmogorov
flow with the size of $\nu^{\frac 23+}$, here $\nu$ is the viscosity
coefficient.",1711.01822v1
2017-11-27,Statistical mechanics of Landau damping,"Landau damping is the tendency of solutions to the Vlasov equation towards
spatially homogeneous distribution functions. The distribution functions
however approach the spatially homogeneous manifold only weakly, and Boltzmann
entropy is not changed by Vlasov equation. On the other hand, density and
kinetic energy density, which are integrals of the distribution function,
approach spatially homogeneous states strongly, which is accompanied by growth
of the hydrodynamic entropy. Such a behavior can be seen when Vlasov equation
is reduced to the evolution equations for density and kinetic energy density by
means of the Ehrenfest reduction.",1711.10022v1
2017-11-29,Lepton-portal Dark Matter in Hidden Valley model and the DAMPE recent results,"We study the recent $e^\pm$ cosmic ray excess reported by DAMPE in a Hidden
Valley Model with lepton-portal dark matter. We find the electron-portal can
account for the excess well and satisfy the DM relic density and direct
detection bounds, while electron+muon/electron+muon+tau-portal suffers from
strong constraints from lepton flavor violating observables, such as $\mu \to 3
e$. We also discuss possible collider signatures of our model, both at the LHC
and a future 100 TeV hadron collider.",1711.11058v3
2017-11-30,"Radiative Dirac neutrino mass, DAMPE dark matter and leptogenesis","We explain the electron-positron excess reported by the DAMPE collaboration
recently in a radiative Dirac seesaw model where a dark $U(1)_X$ gauge symmetry
can (i) forbid the tree-level Yukawa couplings of three right-handed neutrinos
to the standard model lepton and Higgs doublets, (ii) predict the existence of
three dark fermions for the gauge anomaly cancellation, (iii) mediate a
testable scattering of the lightest dark fermion off the nucleons. Our model
can also accommodate a successful leptogenesis to generate the cosmic baryon
asymmetry.",1711.11333v2
2018-02-28,Modal approach to the controllability problem of distributed parameter systems with damping,"This paper is devoted to the controllability analysis of a class of linear
control systems in a Hilbert space. It is proposed to use the minimum energy
controls of a reduced lumped parameter system for solving the infinite
dimensional steering problem approximately. Sufficient conditions of the
approximate controllability are formulated for a modal representation of a
flexible structure with small damping.",1803.00129v1
2018-03-14,Study of Quantum Walk over a Square Lattice,"Quantum random walk finds application in efficient quantum algorithms as well
as in quantum network theory. Here we study the mixing time of a discrete
quantum walk over a square lattice in presence percolation and decoherence. We
consider bit-flip and phase damping noise, and evaluate the instantaneous
mixing time for both the cases. Using numerical analysis we show that in case
of phase damping noise probability distribution of walker's position is
sufficiently close to the uniform distribution after infinite time. However,
during the action of bit-flip noise, even after infinite time the total
variation distance between the two probability distributions is large enough.",1803.05152v1
2018-03-15,Improving the capacity of quantum dense coding by weak measurement and reversal measurement,"A protocol of quantum dense coding protection of two qubits is proposed in
amplitude damping (AD) channel using weak measurement and reversal measurement.
It is found that the capacity of quantum dense coding under the weak
measurement and reversal measurement is always greater than that without weak
measurement and reversal measurement. When the protocol is applied, for the AD
channels with different damping coefficient, the result reflects that quantum
entanglement can be protected and quantum dense coding becomes successful.",1803.05678v1
2018-06-30,A linearized and conservative Fourier pseudo-spectral method for the damped nonlinear Schrödinger equation in three dimensions,"In this paper, we propose a linearized Fourier pseudo-spectral method, which
preserves the total mass and energy conservation laws, for the damped nonlinear
Schr\""{o}dinger equation in three dimensions. With the aid of the semi-norm
equivalence between the Fourier pseudo-spectral method and the finite
difference method, an optimal $L^2$-error estimate for the proposed method
without any restriction on the grid ratio is established by analyzing the real
and imaginary parts of the error function. Numerical results are addressed to
confirm our theoretical analysis.",1807.00091v3
2018-07-11,Global existence and blow-up for semilinear damped wave equations in three space dimensions,"We consider initial value problem for semilinear damped wave equations in
three space dimensions. We show the small data global existence for the problem
without the spherically symmetric assumption and obtain the sharp lifespan of
the solutions. This paper is devoted to a proof of the Takamura's conjecture on
the lifespan of solutions.",1807.04327v3
2018-07-18,B-field induced mixing between Langmuir waves and axions,"We present an analytic study of the dispersion relation for an isotropic
magnetized plasma interacting with axions. We provide a quantitative picture of
the electromagnetic plasma oscillations in both the ultrarelativistic and
nonrelativistic regimes and considering both non-degenerate and degenerate
media, accounting for the dispersion curves as a function of the plasma
temperature and the ratio of the plasma phase velocity to the characteristic
velocity of particles. We include the modifications on the Landau damping of
plasma waves induced by the presence of the axion field, and we comment on the
effects of damping on subluminal plasma oscillations.",1807.06828v2
2018-07-26,Moment conditions and lower bounds in expanding solutions of wave equations with double damping terms,"In this report we obtain higher order asymptotic expansions of solutions to
wave equations with frictional and viscoelastic damping terms. Although the
diffusion phenomena are dominant, differences between the solutions we deal
with and those of heat equations can be seen by comparing the second order
expansions of them. In order to analyze such effects we consider the weighted
L1 initial data. We also give some lower bounds which show the optimality of
obtained expansions.",1807.10020v1
2018-08-16,Continuity of the set equilibria of non-autonomous damped wave equations with terms concentrating on the boundary,"In this paper we are interested in the behavior of the solutions of
non-autonomous damped wave equations when some reaction terms are concentrated
in a neighborhood of the boundary and this neighborhood shrinks to boundary as
a parameter \varepsilon goes to zero. We prove the conti- nuity of the set
equilibria of these equations. Moreover, if an equilibrium solution of the
limit problem is hyperbolic, then we show that the per- turbed equation has one
and only one equilibrium solution nearby.",1808.05667v1
2018-08-30,Protecting temporal correlations of two-qubit states using quantum channels with memory,"Quantum temporal correlations exhibited by violations of Leggett-Garg
Inequality (LGI) and Temporal Steering Inequality (TSI) are in general found to
be non-increasing under decoherence channels when probed on two-qubit pure
entangled states. We study the action of decoherence channels, such as
amplitude damping, phase-damping and depolarising channels when partial memory
is introduced in a way such that two consecutive uses of the channels are
time-correlated. We show that temporal correlations demonstrated by violations
of the above temporal inequalities can be protected against decoherence using
the effect of memory.",1808.10345v1
2018-12-11,Blow up of solutions to semilinear non-autonomous wave equations under Robin boundary conditions,"The problem of blow up of solutions to the initial boundary value problem for
non-autonomous semilinear wave equation with damping and accelerating terms
under the Robin boundary condition is studied. Sufficient conditions of blow up
in a finite time of solutions to semilinear damped wave equations with
arbitrary large initial energy are obtained. A result on blow up of solutions
with negative initial energy of semilinear second order wave equation with
accelerating term is also obtained.",1812.04595v1
2018-12-23,Global existence of weak solutions for strongly damped wave equations with nonlinear boundary conditions and balanced potentials,"We demonstrate the global existence of weak solutions to a class of
semilinear strongly damped wave equations possessing nonlinear hyperbolic
dynamic boundary conditions. Our work assumes $(-\Delta_W)^\theta \partial_tu$
with $\theta\in[\frac{1}{2},1)$ and where $\Delta_W$ is the Wentzell-Laplacian.
Hence, the associated linear operator admits a compact resolvent. A balance
condition is assumed to hold between the nonlinearity defined on the interior
of the domain and the nonlinearity on the boundary. This allows for arbitrary
(supercritical) polynomial growth on each potential, as well as mixed
dissipative/anti-dissipative behavior. Moreover, the nonlinear function defined
on the interior of the domain is assumed to be only $C^0$.",1812.09781v1
2018-12-24,Cold Damping of an Optically Levitated Nanoparticle to micro-Kelvin Temperatures,"We implement a cold damping scheme to cool one mode of the center-of-mass
motion of an optically levitated nanoparticle in ultrahigh vacuum from room
temperature to a record-low temperature of 100 micro-Kelvin. The measured
temperature dependence on feedback gain and thermal decoherence rate is in
excellent agreement with a parameter-free model. We determine the
imprecision-backaction product for our system and provide a roadmap towards
ground-state cooling of optically levitated nanoparticles.",1812.09875v1
2019-01-18,Decay of semilinear damped wave equations:cases without geometric control condition,"We consider the semilinear damped wave equation $\partial_{tt}^2
u(x,t)+\gamma(x)\partial_t u(x,t)=\Delta u(x,t)-\alpha u(x,t)-f(x,u(x,t))$. In
this article, we obtain the first results concerning the stabilization of this
semilinear equation in cases where $\gamma$ does not satisfy the geometric
control condition. When some of the geodesic rays are trapped, the
stabilization of the linear semigroup is semi-uniform in the sense that
$\|e^{At}A^{-1}\|\leq h(t)$ for some function $h$ with $h(t)\rightarrow 0$ when
$t\rightarrow +\infty$. We provide general tools to deal with the semilinear
stabilization problem in the case where $h(t)$ has a sufficiently fast decay.",1901.06169v1
2019-02-04,Non-Markovian Effects on Overdamped Systems,"We study the consequences of adopting the memory dependent, non-Markovian,
physics with the memory-less over-damped approximation usually employed to
investigate Brownian particles. Due to the finite correlation time scale
associated with the noise, the stationary behavior of the system is not
described by the Boltzmann-Gibbs statistics. However, the presence of a very
weak external white noise can be used to regularize the equilibrium properties.
Surprisingly, the coupling to another bath effectively restores the dynamical
aspects missed by the over-damped treatment.",1902.01356v1
2019-02-06,Stability analysis of a 1D wave equation with a nonmonotone distributed damping,"This paper is concerned with the asymptotic stability analysis of a one
dimensional wave equation subject to a nonmonotone distributed damping. A
well-posedness result is provided together with a precise characterization of
the asymptotic behavior of the trajectories of the system under consideration.
The well-posedness is proved in the nonstandard L p functional spaces, with p
$\in$ [2, $\infty$], and relies mostly on some results collected in Haraux
(2009). The asymptotic behavior analysis is based on an attractivity result on
a specific infinite-dimensional linear time-variant system.",1902.02050v1
2019-02-13,"Comment on ""Quantization of the damped harmonic oscillator"" [Serhan et al, J. Math. Phys. 59, 082105 (2018)]","A recent paper [J. Math. Phys. {\bf 59}, 082105 (2018)] constructs a
Hamiltonian for the (dissipative) damped harmonic oscillator. We point out that
non-Hermiticity of this Hamiltonian has been ignored to find real discrete
eigenvalues which are actually non-real. We emphasize that non-Hermiticity in
Hamiltonian is crucial and it is a quantal signature of dissipation.",1902.04895v1
2019-02-15,Memory effects teleportation of quantum Fisher information under decoherence,"We have investigated how memory effects on the teleportation of quantum
Fisher information(QFI) for a single qubit system using a class of X-states as
resources influenced by decoherence channels with memory, including amplitude
damping, phase-damping and depolarizing channels. Resort to the definition of
QFI, we first derive the explicit analytical results of teleportation of QFI
with respect to weight parameter $\theta$ and phase parameter $\phi$ under the
decoherence channels. Component percentages, the teleportation of QFI for a
two-qubit entanglement system has also been addressed. The remarkable
similarities and differences among these two situations are also analyzed in
detail and some significant results are presented.",1902.05668v1
2019-02-23,Uniform decay rates for a suspension bridge with locally distributed nonlinear damping,"We study a nonlocal evolution equation modeling the deformation of a bridge,
either a footbridge or a suspension bridge. Contrarily to the previous
literature we prove the asymptotic stability of the considered model with a
minimum amount of damping which represents less cost of material. The result is
also numerically proved.",1902.09963v1
2019-03-01,Spectra of the Dissipative Spin Chain,"This paper generalizes the (0+1)-dimensional spin-boson problem to the
corresponding (1+1)-dimensional version. Monte Carlo simulation is used to find
the phase diagram and imaginary time correlation function. The real frequency
spectrum is recovered by the newly developed P\'ade regression analytic
continuation method. We find that, as dissipation strength $\alpha$ is
increased, the sharp quasi-particle spectrum is broadened and the peak
frequency is lower. According to the behavior of the low frequency spectrum, we
classify the dynamical phase into three different regions: weakly damped,
linear $k$-edge, and strongly damped.",1903.00567v1
2019-03-17,Sensing Kondo correlations in a suspended carbon nanotube mechanical resonator with spin-orbit coupling,"We study electron mechanical coupling in a suspended carbon nanotube (CNT)
quantum dot device. Electron spin couples to the flexural vibration mode due to
spin-orbit coupling in the electron tunneling processes. In the weak coupling
limit, i.e. electron-vibration coupling is much smaller than the electron
energy scale, the damping and resonant frequency shift of the CNT resonator can
be obtained by calculating the dynamical spin susceptibility. We find that
strong spin-flip scattering processes in Kondo regime significantly affect the
mechanical motion of the carbon nanotube: Kondo effect induces strong damping
and frequency shift of the CNT resonator.",1903.07049v1
2019-03-27,Lifespan of semilinear generalized Tricomi equation with Strauss type exponent,"In this paper, we consider the blow-up problem of semilinear generalized
Tricomi equation. Two blow-up results with lifespan upper bound are obtained
under subcritical and critical Strauss type exponent. In the subcritical case,
the proof is based on the test function method and the iteration argument. In
the critical case, an iteration procedure with the slicing method is employed.
This approach has been successfully applied to the critical case of semilinear
wave equation with perturbed Laplacian or the damped wave equation of
scattering damping case. The present work gives its application to the
generalized Tricomi equation.",1903.11351v2
2019-04-01,A remark on semi-linear damped $σ$-evolution equations with a modulus of continuity term in nonlinearity,"In this article, we indicate that under suitable assumptions of a modulus of
continuity we obtain either the global (in time) existence of small data
Sobolev solutions or the blow-up result of local (in time) Sobolev solutions to
semi-linear damped $\sigma$-evolution equations with a modulus of continuity
term in nonlinearity.",1904.00698v3
2019-04-05,Critical regularity of nonlinearities in semilinear classical damped wave equations,"In this paper we consider the Cauchy problem for the semilinear damped wave
equation
  $u_{tt}-\Delta u + u_t = h(u);\qquad u(0;x) = f(x); \quad u_t(0;x) = g(x);$
  where $h(s) = |s|^{1+2/n}\mu(|s|)$. Here n is the space dimension and $\mu$
is a modulus of continuity. Our goal is to obtain sharp conditions on $\mu$ to
obtain a threshold between global (in time) existence of small data solutions
(stability of the zerosolution) and blow-up behavior even of small data
solutions.",1904.02939v1
2019-04-29,Origin of the DAMPE 1.4 TeV peak,"Recent accurate measurements of cosmic ray electron flux by the Dark Matter
Particle Explorer (DAMPE) reveal a sharp peak structure near 1.4 TeV, which is
difficult to explain by standard astrophysical processes. In this letter, we
propose a simple model that the enhanced dark matter annihilation via the
$e^+e^-$ channel and with the thermal relic annihilation cross section around
the current nearest black hole (A0620-00) can satisfactorily account for the
sharp peak structure. The predicted dark matter mass is $\sim 1.5-3$ TeV.",1904.12418v1
2019-08-03,Lindblad dynamics of the damped and forced quantum harmonic oscillator,"The quantum dynamics of a damped and forced harmonic oscillator is
investigated in terms of a Lindblad master equation. Elementary algebraic
techniques are employed allowing for example to analyze the long time behavior,
i.e. the quantum limit cycle. The time evolution of various expectation values
is obtained in closed form as well as the entropy and the Husimi phase space
distribution. We also discuss the related description in terms of a
non-Hermitian Hamiltonian.",1908.01187v2
2019-08-07,Decay estimates for the linear damped wave equation on the Heisenberg group,"This paper is devoted to the derivation of $L^2$ - $L^2$ decay estimates for
the solution of the homogeneous linear damped wave equation on the Heisenberg
group $\mathbf{H}_n$, for its time derivative and for its horizontal gradient.
Moreover, we consider the improvement of these estimates when further
$L^1(\mathbf{H}_n)$ regularity is required for the Cauchy data. Our approach
will rely strongly on the group Fourier transform of $\mathbf{H}_n$ and on the
properties of the Hermite functions that form a maximal orthonormal system for
$L^2(\mathbb{R}^n)$ of eigenfunctions of the harmonic oscillator.",1908.02657v1
2019-08-08,Critical exponent of Fujita-type for the semilinear damped wave equation on the Heisenberg group with power nonlinearity,"In this paper, we consider the Cauchy problem for the semilinear damped wave
equation on the Heisenberg group with power nonlinearity. We prove that the
critical exponent is the Fujita exponent $p_{\mathrm{Fuj}}(\mathscr{Q}) = 1+2 /
\mathscr{Q}$, where $\mathscr{Q}$ is the homogeneous dimension of the
Heisenberg group. On the one hand, we will prove the global existence of small
data solutions for $p >p_{\mathrm{Fuj}}(\mathscr{Q})$ in an exponential
weighted energy space. On the other hand, a blow-up result for $1 < p \leq
p_{\mathrm{Fuj}}(\mathscr{Q})$ under certain integral sign assumptions for the
Cauchy data by using the test function method.",1908.02989v1
2019-11-03,Linear Inviscid Damping in Sobolev and Gevrey Spaces,"In a recent article Jia established linear inviscid damping in Gevrey
regularity for compactly supported Gevrey regular shear flows in a finite
channel, which is of great interest in view of existing nonlinear results. In
this article we provide an alternative very short proof of stability in Gevrey
regularity as a consequence of stability in high Sobolev regularity. Here, we
consider both the setting of a finite channel with compactly supported
perturbations and of an infinite channel without this restriction. Furthermore,
we consider the setting where perturbations vanish only of finite order.",1911.00880v1
2019-11-03,A global existence result for two-dimensional semilinear strongly damped wave equation with mixed nonlinearity in an exterior domain,"We study two-dimensional semilinear strongly damped wave equation with mixed
nonlinearity $|u|^p+|u_t|^q$ in an exterior domain, where $p,q>1$. Assuming the
smallness of initial data in exponentially weighted spaces and some conditions
on powers of nonlinearity, we prove global (in time) existence of small data
energy solution with suitable higher regularity by using a weighted energy
method.",1911.00899v1
2019-11-05,Critical exponent for a weakly coupled system of semi-linear $σ$-evolution equations with frictional damping,"We are interested in studying the Cauchy problem for a weakly coupled system
of semi-linear $\sigma$-evolution equations with frictional damping. The main
purpose of this paper is two-fold. We would like to not only prove the global
(in time) existence of small data energy solutions but also indicate the
blow-up result for Sobolev solutions when $\sigma$ is assumed to be any
fractional number.",1911.01946v1
2019-11-11,Existence and nonexistence of global solutions for a structurally damped wave system with power nonlinearities,"Our interest itself of this paper is strongly inspired from an open problem
in the paper [1] published by D'Abbicco. In this article, we would like to
study the Cauchy problem for a weakly coupled system of semi-linear
structurally damped wave equations. Main goal is to find the threshold, which
classifies the global (in time) existence of small data solutions or the
nonexistence of global solutions under the growth condition of the
nonlinearities.",1911.04412v1
2019-11-15,Some $L^1$-$L^1$ estimates for solutions to visco-elastic damped $σ$-evolution models,"This note is to conclude $L^1-L^1$ estimates for solutions to the following
Cauchy problem for visco-elastic damped $\sigma$-evolution models:
\begin{equation} \begin{cases} u_{tt}+ (-\Delta)^\sigma u+ (-\Delta)^\sigma u_t
= 0, &\quad x\in \mathbb{R}^n,\, t \ge 0, \\ u(0,x)= u_0(x),\quad
u_t(0,x)=u_1(x), &\quad x\in \mathbb{R}^n, \label{pt1.1} \end{cases}
\end{equation} where $\sigma> 1$, in all space dimensions $n\ge 1$.",1911.06563v1
2019-11-22,Long-time asymptotics for a coupled thermoelastic plate-membrane system,"In this paper we consider a transmission problem for a system of a
thermoelastic plate with (or without) rotational inertia term coupled with a
membrane with different variants of damping for the plate and/or the membrane.
We prove well-posedness of the problem and higher regularity of the solution
and study the asymptotic behaviour of the solution, depending on the damping
and on the presence of the rotational term.",1911.10161v1
2019-11-28,Tikhonov regularization of a second order dynamical system with Hessian driven damping,"We investigate the asymptotic properties of the trajectories generated by a
second-order dynamical system with Hessian driven damping and a Tikhonov
regularization term in connection with the minimization of a smooth convex
function in Hilbert spaces. We obtain fast convergence results for the function
values along the trajectories. The Tikhonov regularization term enables the
derivation of strong convergence results of the trajectory to the minimizer of
the objective function of minimum norm.",1911.12845v2
2019-12-15,"Negative mobility, sliding and delocalization for stochastic networks","We consider prototype configurations for quasi-one-dimensional stochastic
networks that exhibit negative mobility, meaning that current decreases or even
reversed as the bias is increased. We then explore the implications of
disorder. In particular we ask whether lower and upper bias thresholds restrict
the possibility to witness non-zero current (sliding and anti-sliding
transitions respectively), and whether a delocalization effect manifest itself
(crossover from over-damped to under-damped relaxation). In the latter context
detailed analysis of the relaxation spectrum as a function of the bias is
provided for both on-chain and off-chain disorder.",1912.07059v2
2019-12-23,On a damped Szego equation (with an appendix in collaboration with Christian Klein),"We investigate how damping the lowest Fourier mode modifies the dynamics of
the cubic Szeg{\""o} equation. We show that there is a nonempty open subset of
initial data generating trajec-tories with high Sobolev norms tending to
infinity. In addition, we give a complete picture of this phenomenon on a
reduced phase space of dimension 6. An appendix is devoted to numerical
simulations supporting the generalisation of this picture to more general
initial data.",1912.10933v1
2020-03-20,The Cauchy problem of the semilinear second order evolution equation with fractional Laplacian and damping,"In the present paper, we prove time decay estimates of solutions in weighted
Sobolev spaces to the second order evolution equation with fractional Laplacian
and damping for data in Besov spaces. Our estimates generalize the estimates
obtained in the previous studies. The second aim of this article is to apply
these estimates to prove small data global well-posedness for the Cauchy
problem of the equation with power nonlinearities. Especially, the estimates
obtained in this paper enable us to treat more general conditions on the
nonlinearities and the spatial dimension than the results in the previous
studies.",2003.09239v1
2020-03-31,Time-Asymptotics of Physical Vacuum Free Boundaries for Compressible Inviscid Flows with Damping,"In this paper, we prove the leading term of time-asymptotics of the moving
vacuum boundary for compressible inviscid flows with damping to be that for
Barenblatt self-similar solutions to the corresponding porous media equations
obtained by simplifying momentum equations via Darcy's law plus the possible
shift due to the movement of the center of mass, in the one-dimensional and
three-dimensional spherically symmetric motions, respectively. This gives a
complete description of the large time asymptotic behavior of solutions to the
corresponding vacuum free boundary problems. The results obtained in this paper
are the first ones concerning the large time asymptotics of physical vacuum
boundaries for compressible inviscid fluids, to the best of our knowledge.",2003.14072v2
2020-05-06,Zero-dimensional models for gravitational and scalar QED decoherence,"We investigate the dynamics of two quantum mechanical oscillator system-bath
toy models obtained by truncating to zero spatial dimensions linearized gravity
coupled to a massive scalar field and scalar QED. The scalar-gravity toy model
maps onto the phase damped oscillator, while the scalar QED toy model
approximately maps onto an oscillator system subject to two-photon damping. The
toy models provide potentially useful insights into solving for open system
quantum dynamics relevant to the full scalar QED and weak gravitational field
systems, in particular operational probes of the decoherence for initial scalar
field system superposition states.",2005.02554v2
2020-05-16,On the asymptotic stability of wave equations coupled by velocities of anti-symmetric type,"In this paper, we study the asymptotic stability of two wave equations
coupled by velocities of anti-symmetric type via only one damping. We adopt the
frequency domain method to prove that the system with smooth initial data is
logarithmically stable, provided that the coupling domain and the damping
domain intersect each other. Moreover, we show, by an example, that this
geometric assumption of the intersection is necessary for 1-D case.",2005.07977v2
2020-05-27,On the blow-up of solutions to semilinear damped wave equations with power nonlinearity in compact Lie groups,"In this note, we prove a blow-up result for the semilinear damped wave
equation in a compact Lie group with power nonlinearity $|u|^p$ for any $p>1$,
under suitable integral sign assumptions for the initial data, by using an
iteration argument. A byproduct of this method is the upper bound estimate for
the lifespan of a local in time solution. As a preliminary result, a local (in
time) existence result is proved in the energy space via Fourier analysis on
compact Lie groups.",2005.13479v2
2020-06-13,On the well-posedness of the damped time-harmonic Galbrun equation and the equations of stellar oscillations,"We study the time-harmonic Galbrun equation describing the propagation of
sound in the presence of a steady background flow. With additional rotational
and gravitational terms these equations are also fundamental in helio- and
asteroseismology as a model for stellar oscillations. For a simple damping
model we prove well-posedness of these equations, i.e. uniqueness, existence,
and stability of solutions under mild conditions on the parameters (essentially
subsonic flows). The main tool of our analysis is a generalized Helmholtz
decomposition.",2006.07658v1
2020-06-22,Prediction of short time qubit readout via measurement of the next quantum jump of a coupled damped driven harmonic oscillator,"The dynamics of the next quantum jump for a qubit [two level system] coupled
to a readout resonator [damped driven harmonic oscillator] is calculated. A
quantum mechanical treatment of readout resonator reveals non exponential short
time behavior which could facilitate detection of the state of the qubit faster
than the resonator lifetime.",2006.11950v1
2020-08-17,Dynamics of spatially indistinguishable particles and entanglement protection,"We provide a general framework which allows one to obtain the dynamics of $N$
noninteracting spatially indistinguishable particles locally coupled to
separated environments. The approach is universal, being valid for both bosons
and fermions and for any type of system-environment interaction. It is then
applied to study the dynamics of two identical qubits under paradigmatic
Markovian noises, such as phase damping, depolarizing and amplitude damping. We
find that spatial indistinguishability of identical qubits is a controllable
intrinsic property of the system which protects quantum entanglement against
detrimental noise.",2008.07471v1
2020-09-02,Discriminating qubit amplitude damping channels,"We address the issue of the discrimination between two-qubit amplitude
damping channels by exploring several strategies. For the single-shot, we show
that the excited state does not always give the optimal input, and that side
entanglement assistance has limited benefit. On the contrary, feedback
assistance from the environment is more beneficial. For the two-shot, we prove
the in-utility of entangled inputs. Then focusing on individual (local)
measurements, we find the optimal adaptive strategy.",2009.01000v3
2020-09-03,Asymptotic behavior of 2D stably stratified fluids with a damping term in the velocity equation,"This article is concerned with the asymptotic behavior of the two-dimensional
inviscid Boussinesq equations with a damping term in the velocity equation.
Precisely, we provide the time-decay rates of the smooth solutions to that
system. The key ingredient is a careful analysis of the Green kernel of the
linearized problem in Fourier space, combined with bilinear estimates and
interpolation inequalities for handling the nonlinearity.",2009.01578v2
2020-08-05,The perturbational stability of the Schr$\ddot{o}$dinger equation,"By using the Wigner transform, it is shown that the nonlinear
Schr$\ddot{\textmd{o}}$dinger equation can be described, in phase space, by a
kinetic theory similar to the Vlasov equation which is used for describing a
classical collisionless plasma. In this paper we mainly show Landau damping in
the quantum sense, namely,quantum Landau damping exists for the Wigner-Poisson
system. At the same time, we also prove the existence and the stability of the
nonlinear Schr$\ddot{\textmd{o}}$dinger equation under the quantum stability
assumption.",2009.09855v1
2020-10-12,Long time behavior of solutions for a damped Benjamin-Ono equation,"We consider the Benjamin-Ono equation on the torus with an additional damping
term on the smallest Fourier modes (cos and sin). We first prove global
well-posedness of this equation in $L^2_{r,0}(\mathbb{T})$. Then, we describe
the weak limit points of the trajectories in $L^2_{r,0}(\mathbb{T})$ when time
goes to infinity, and show that these weak limit points are strong limit
points. Finally, we prove the boundedness of higher-order Sobolev norms for
this equation. Our key tool is the Birkhoff map for the Benjamin-Ono equation,
that we use as an adapted nonlinear Fourier transform.",2010.05520v1
2020-10-18,Classical limit of quantum mechanics for damped driven oscillatory systems: Quantum-classical correspondence,"The investigation of quantum-classical correspondence may lead to gain a
deeper understanding of the classical limit of quantum theory. We develop a
quantum formalism on the basis of a linear-invariant theorem, which gives an
exact quantum-classical correspondence for damped oscillatory systems that are
perturbed by an arbitrary force. Within our formalism, the quantum trajectory
and expectation values of quantum observables are precisely coincide with their
classical counterparts in the case where we remove the global quantum constant
h from their quantum results. In particular, we illustrate the correspondence
of the quantum energy with the classical one in detail.",2010.08971v1
2020-10-21,Initial boundary value problem for a strongly damped wave equation with a general nonlinearity,"In this paper, a strongly damped semilinear wave equation with a general
nonlinearity is considered. With the help of a newly constructed auxiliary
functional and the concavity argument, a general finite time blow-up criterion
is established for this problem. Furthermore, the lifespan of the weak solution
is estimated from both above and below. This partially extends some results
obtained in recent literatures and sheds some light on the similar effect of
power type nonlinearity and logarithmic nonlinearity on finite time blow-up of
solutions to such problems.",2010.10696v1
2020-10-21,MRI Image Recovery using Damped Denoising Vector AMP,"Motivated by image recovery in magnetic resonance imaging (MRI), we propose a
new approach to solving linear inverse problems based on iteratively calling a
deep neural-network, sometimes referred to as plug-and-play recovery. Our
approach is based on the vector approximate message passing (VAMP) algorithm,
which is known for mean-squared error (MSE)-optimal recovery under certain
conditions. The forward operator in MRI, however, does not satisfy these
conditions, and thus we design new damping and initialization schemes to help
VAMP. The resulting DD-VAMP++ algorithm is shown to outperform existing
algorithms in convergence speed and accuracy when recovering images from the
fastMRI database for the practical case of Cartesian sampling.",2010.11321v1
2020-11-05,Mathematical modelling of an unstable bent flow using the selective frequency damping method,"The selective frequency damping method was applied to a bent flow. The method
was used in an adaptive formulation. The most dangerous frequency was
determined by solving an eigenvalue problem. It was found that one of the
patterns, steady-state or pulsating, may exist at some relatively high Reynolds
numbers. The periodic flow occurs due to the instability of the steady-state
flow. This numerical method is easy to use but requires a great deal of time
for calculations.",2011.02646v1
2020-11-04,"The ""Dark disk"" model in the light of DAMPE experiment","There are a lot of models considering the Dark Matter (DM) to be the origin
of cosmic ray (CR) positron excess. However, they face an obstacle in the form
of gamma-rays. Simple DM models tend to overproduce gamma-rays, leading to
contradiction with isotropic gamma-ray background (IGRB). The <<dark disk>>
model has been proposed to alleviate this contradiction. This work considers
results of DAMPE experiment in the framework of the disk model. It is obtained
that such a framework allows improving data fit considerably.",2011.04425v2
2021-02-04,Global existence results for semi-linear structurally damped wave equations with nonlinear convection,"In this paper, we consider the Cauchy problem for semi-linear wave equations
with structural damping term $\nu (-\Delta)^2 u_t$, where $\nu >0$ is a
constant. As being mentioned in [8,10], the linear principal part brings both
the diffusion phenomenon and the regularity loss of solutions. This implies
that, for the nonlinear problems, the choice of solution spaces plays an
important role to obtain global solutions with sharp decay properties in time.
Our main purpose of this paper is to prove the global (in time) existence of
solutions for the small data and their decay properties for the supercritical
nonlinearities.",2102.02445v2
2021-02-14,Suppression of singularities of solutions of the Euler-Poisson system with density-dependent damping,"We find a sharp condition on the density-dependent coefficient of damping of
a one-dimensional repulsive Euler-Poisson system, which makes it possible to
suppress the formation of singularities in the solution of the Cauchy problem
with arbitrary smooth data. In the context of plasma physics, this means the
possibility of suppressing the breakdown of arbitrary oscillations of cold
plasma.",2102.07176v2
2021-02-15,"Piezoelectric beam with magnetic effect, time-varying delay and time-varying weights","The main result of this work is to obtain the exponential decay of the
solutions of a piezoelectric beam model with magnetic effect and delay term.
The dampings are inserted into the equation of longitudinal displacement. The
terms of damping, whose weight associated with them varies over time, are of
the friction type, and one of them has delay. This work will also address the
issue of existence and uniqueness of solution for the model.",2102.07538v1
2021-02-23,Effects of ground-state correlations on damping of giant dipole resonaces in $LS$ closed shell nuclei,"The effects of ground-state correlations on the damping of isovector giant
dipole resonances in $LS$ closed shell nuclei $^{16}$O and $^{40}$Ca are
studied using extended random-phase-approximation (RPA) approaches derived from
the time-dependent density-matrix theory. It is pointed out that unconventional
two-body amplitudes of one particle--three hole and three particle--one hole
types which are neglected in most extended RPA theories play an important role
in the fragmentation of isovector dipole strength.",2102.11505v2
2021-02-28,The influence of the physical coefficients of a Bresse system with one singular local viscous damping in the longitudinal displacement on its stabilization,"In this paper, we investigate the stabilization of a linear Bresse system
with one singular local frictional damping acting in the longitudinal
displacement, under fully Dirichlet boundary conditions. First, we prove the
strong stability of our system. Next, using a frequency domain approach
combined with the multiplier method, we establish the exponential stability of
the solution if and only if the three waves have the same speed of propagation.
On the contrary, we prove that the energy of our system decays polynomially
with rates $t^{-1}$ or $t^{-\frac{1}{2}}$.",2103.00628v2
2021-03-01,On a damped nonlinear beam equation,"In this note we analyze the large time behavior of solutions to an
initial/boundary problem involving a damped nonlinear beam equation. We show
that under physically realistic conditions on the nonlinear terms in the
equation of motion the energy is a decreasing function of time and solutions
converge to a stationary solution with respect to a desirable norm.",2103.00969v3
2021-03-05,Universal spin wave damping in magnetic Weyl semimetals,"We analyze the decay of spin waves into Stoner excitations in magnetic Weyl
semimetals. The lifetime of a mode is found to have a universal dependence on
its frequency and momentum, and on a few parameters that characterize the
relativistic Weyl spectrum. At the same time, Gilbert damping by Weyl electrons
is absent. The decay rate of spin waves is calculated perturbatively using the
s-d model of itinerant Weyl or Dirac electrons coupled to local moments. We
show that many details of the Weyl spectrum, such as the momentum-space
locations, dispersions and sizes of the Weyl Fermi pockets, can be deduced
indirectly by probing the spin waves of local moments using inelastic neutron
scattering.",2103.03885v1
2021-03-23,Fast convergence of dynamical ADMM via time scaling of damped inertial dynamics,"In this paper, we propose in a Hilbertian setting a second-order
time-continuous dynamic system with fast convergence guarantees to solve
structured convex minimization problems with an affine constraint. The system
is associated with the augmented Lagrangian formulation of the minimization
problem. The corresponding dynamics brings into play three general time-varying
parameters, each with specific properties, and which are respectively
associated with viscous damping, extrapolation and temporal scaling. By
appropriately adjusting these parameters, we develop a Lyapunov analysis which
provides fast convergence properties of the values and of the feasibility gap.
These results will naturally pave the way for developing corresponding
accelerated ADMM algorithms, obtained by temporal discretization.",2103.12675v1
2021-03-29,Comparison between the Cauchy problem and the scattering problem for the Landau damping in the Vlasov-HMF equation,"We analyze the analytic Landau damping problem for the Vlasov-HMF equation,
by fixing the asymptotic behavior of the solution. We use a new method for this
""scattering problem"", closer to the one used for the Cauchy problem. In this
way we are able to compare the two results, emphasizing the different influence
of the plasma echoes in the two approaches. In particular, we prove a
non-perturbative result for the scattering problem.",2103.15932v2
2021-04-06,Realising Einstein's mirror: Optomechanical damping with a thermal photon gas,"In 1909 Einstein described the thermalization of a mirror within a blackbody
cavity by collisions with thermal photons. While the time to thermalize the
motion of even a microscale or nanoscale object is so long that it is not
feasible, we show that it is using the high intensity light from an amplified
thermal light source with a well-defined chemical potential. We predict damping
of the center-of mass motion due to this effect on times scales of seconds for
small optomechanical systems, such as levitated nanoparticles, allowing
experimental observation.",2104.02708v2
2021-04-12,The pressureless damped Euler-Riesz equations,"In this paper, we analyze the pressureless damped Euler-Riesz equations posed
in either $\mathbb{R}^d$ or $\mathbb{T}^d$. We construct the global-in-time
existence and uniqueness of classical solutions for the system around a
constant background state. We also establish large-time behaviors of classical
solutions showing the solutions towards the equilibrium as time goes to
infinity. For the whole space case, we first show the algebraic decay rate of
solutions under additional assumptions on the initial data compared to the
existence theory. We then refine the argument to have the exponential decay
rate of convergence even in the whole space. In the case of the periodic
domain, without any further regularity assumptions on the initial data, we
provide the exponential convergence of solutions.",2104.05153v1
2021-04-12,Fractional time stepping and adjoint based gradient computation in an inverse problem for a fractionally damped wave equation,"In this paper we consider the inverse problem of identifying the initial data
in a fractionally damped wave equation from time trace measurements on a
surface, as relevant in photoacoustic or thermoacoustic tomography. We derive
and analyze a time stepping method for the numerical solution of the
corresponding forward problem. Moreover, to efficiently obtain reconstructions
by minimizing a Tikhonov regularization functional (or alternatively, by
computing the MAP estimator in a Bayesian approach), we develop an adjoint
based scheme for gradient computation. Numerical reconstructions in two space
dimensions illustrate the performance of the devised methods.",2104.05577v1
2021-04-15,Explaining Neptune's Eccentricity,"Early migration damped Neptune's eccentricity. Here, we assume that the
damped value was much smaller than the value observed today, and show that the
closest flyby of $\sim 0.1 \; \mathrm{M_{\odot}}$ star over $\sim 4.5
\mathrm{\; Gyr}$ in the field, at a distance of $\sim 10^3 \mathrm{\; AU}$
would explain the value of Neptune's eccentricity observed today.",2104.07672v3
2021-04-17,Lifespan estimates for wave equations with damping and potential posed on asymptotically Euclidean manifolds,"In this work, we investigate the problem of finite time blow up as well as
the upper bound estimates of lifespan for solutions to small-amplitude
semilinear wave equations with time dependent damping and potential, and mixed
nonlinearities $c_1 |u_t|^p+c_2 |u|^q$, posed on asymptotically Euclidean
manifolds, which is related to both the Strauss conjecture and the Glassey
conjecture.",2104.08497v2
2021-05-20,On the the critical exponent for the semilinear Euler-Poisson-Darboux-Tricomi equation with power nonlinearity,"In this note, we derive a blow-up result for a semilinear generalized Tricomi
equation with damping and mass terms having time-dependent coefficients. We
consider these coefficients with critical decay rates. Due to this threshold
nature of the time-dependent coefficients (both for the damping and for the
mass), the multiplicative constants appearing in these lower-order terms
strongly influence the value of the critical exponent, determining a
competition between a Fujita-type exponent and a Strauss-type exponent.",2105.09879v2
2021-06-02,Convergent dynamics of optimal nonlinear damping control,"Following Demidovich's concept and definition of convergent systems, we
analyze the optimal nonlinear damping control, recently proposed [1] for the
second-order systems. Targeting the problem of output regulation,
correspondingly tracking of $\mathcal{C}^1$-trajectories, it is shown that all
solutions of the control system are globally uniformly asymptotically stable.
The existence of the unique limit solution in the origin of the control error
and its time derivative coordinates are shown in the sense of Demidovich's
convergent dynamics. Explanative numerical examples are also provided along
with analysis.",2106.00962v1
2021-06-26,Role of Dissipation on the Stability of a Parametrically Driven Quantum Harmonic Oscillator,"We study the dissipative dynamics of a single quantum harmonic oscillator
subjected to a parametric driving with in an effective Hamiltonian approach.
Using Liouville von Neumann approach, we show that the time evolution of a
parametrically driven dissipative quantum oscillator has a strong connection
with the classical damped Mathieu equation. Based on the numerical analysis of
the Monodromy matrix, we demonstrate that the dynamical instability generated
by the parametric driving are reduced by the effect of dissipation. Further, we
obtain a closed relationship between the localization of the Wigner function
and the stability of the damped Mathieu equation.",2106.14018v1
2021-07-11,Space-time arithmetic quasi-periodic homogenization for damped wave equations,"This paper is concerned with space-time homogenization problems for damped
wave equations with spatially periodic oscillating elliptic coefficients and
temporally (arithmetic) quasi-periodic oscillating viscosity coefficients. Main
results consist of a homogenization theorem, qualitative properties of
homogenized matrices which appear in homogenized equations and a corrector
result for gradients of solutions. In particular, homogenized equations and
cell problems will turn out to deeply depend on the quasi-periodicity as well
as the log ratio of spatial and temporal periods of the coefficients. Even
types of equations will change depending on the log ratio and
quasi-periodicity. Proofs of the main results are based on a (very weak)
space-time two-scale convergence theory.",2107.04966v1
2021-07-29,Global existence for damped $σ$-evolution equations with nonlocal nonlinearity,"In this research, we would like to study the global (in time) existence of
small data solutions to the following damped $\sigma$-evolution equations with
nonlocal (in space) nonlinearity: \begin{equation*}
\partial_{t}^{2}u+(-\Delta)^{\sigma}u+\partial_{t}u+(-\Delta)^{\sigma}\partial_{t}u=I_{\alpha}(|u|^{p}),
\ \ t>0, \ \ x\in \mathbb{R}^{n}, \end{equation*} where $\sigma\geq1$, $p>1$
and $I_{\alpha}$ is the Riesz potential of power nonlinearity $|u|^{p}$ for any
$\alpha\in (0,n)$. More precisely, by using the $(L^{m}\cap L^{2})-L^{2}$ and
$L^{2}-L^{2}$ linear estimates, where $m\in[1,2]$, we show the new influence of
the parameter $\alpha$ on the admissible ranges of the exponent $p$.",2107.13924v1
2021-08-17,Estimate of the attractive velocity of attractors for some dynamical systems,"In this paper, we first prove an abstract theorem on the existence of
polynomial attractors and the concrete estimate of their attractive velocity
for infinite-dimensional dynamical systems, then apply this theorem to a class
of wave equations with nonlocal weak damping and anti-damping in case that the
nonlinear term~$f$~is of subcritical growth.",2108.07410v4
2021-08-27,Distributed Mirror Descent Algorithm with Bregman Damping for Nonsmooth Constrained Optimization,"To solve distributed optimization efficiently with various constraints and
nonsmooth functions, we propose a distributed mirror descent algorithm with
embedded Bregman damping, as a generalization of conventional distributed
projection-based algorithms. In fact, our continuous-time algorithm well
inherits good capabilities of mirror descent approaches to rapidly compute
explicit solutions to the problems with some specific constraint structures.
Moreover, we rigorously prove the convergence of our algorithm, along with the
boundedness of the trajectory and the accuracy of the solution.",2108.12136v1
2021-08-27,Non relativistic and ultra relativistic limits in 2d stochastic nonlinear damped Klein-Gordon equation,"We study the non relativistic and ultra relativistic limits in the
two-dimensional nonlinear damped Klein-Gordon equation driven by a space-time
white noise on the torus. In order to take the limits, it is crucial to clarify
the parameter dependence in the estimates of solution. In this paper we present
two methods to confirm this parameter dependence. One is the classical, simple
energy method. Another is the method via Strichartz estimates.",2108.12183v4
2021-09-08,The isothermal limit for the compressible Euler equations with damping,"We consider the isothermal Euler system with damping. We rigorously show the
convergence of Barenblatt solutions towards a limit Gaussian profile in the
isothermal limit $\gamma$ $\rightarrow$ 1, and we explicitly compute the
propagation and the behavior of Gaussian initial data. We then show the weak L
1 convergence of the density as well as the asymptotic behavior of its first
and second moments. Contents 1. Introduction 1 2. Assumptions and main results
3 3. The limit $\gamma$ $\rightarrow$ 1 of Barenblatt's solutions 6 4. Gaussian
solutions 9 5. Evolution of certain quantities 10 6. Convergence 15 7.
Conclusion 17 References 17",2109.03590v1
2021-11-01,Strong solution of modified 3D-Navier-stockes equations,"In this paper we study the incompressible Navier-Stokes equations with
logarithme damping {\alpha} log(e + |u|2)|u|2u, where we used new methods, new
tools and Fourier analysis",2111.00859v2
2021-11-02,Blow-up of solutions to semilinear wave equations with a time-dependent strong damping,"The paper investigates a class of a semilinear wave equation with
time-dependent damping term ($-\frac{1}{{(1+t)}^{\beta}}\Delta u_t$) and a
nonlinearity $|u|^p$. We will show the influence of the the parameter $\beta$
in the blow-up results under some hypothesis on the initial data and the
exponent $p$ by using the test function method. We also study the local
existence in time of mild solution in the energy space $H^1(\mathbb{R}^n)\times
L^2(\mathbb{R}^n)$.",2111.01433v1
2021-11-02,Around plane waves solutions of the Schr{ö}dinger-Langevin equation,"We consider the logarithmic Schr{\""o}dinger equations with damping, also
called Schr{\""o}dinger-Langevin equation. On a periodic domain, this equation
possesses plane wave solutions that are explicit. We prove that these solutions
are asymptotically stable in Sobolev regularity. In the case without damping,
we prove that for almost all value of the nonlinear parameter, these solutions
are stable in high Sobolev regularity for arbitrary long times when the
solution is close to a plane wave. We also show and discuss numerical
experiments illustrating our results.",2111.01487v1
2021-11-11,Stabilization for Euler-Bernoulli beam equation with a local degenerated Kelvin-Voigt damping,"We consider the Euler-Bernoulli beam equation with a local Kelvin-Voigt
dissipation type in the interval $(-1,1)$. The coefficient damping is only
effective in $(0,1)$ and is degenerating near the $0$ point with a speed at
least equal to $x^{\alpha}$ where $\alpha\in(0,5)$. We prove that the semigroup
corresponding to the system is polynomially stable and the decay rate depends
on the degeneracy speed $\alpha$.",2111.06431v1
2021-11-12,GCGE: A Package for Solving Large Scale Eigenvalue Problems by Parallel Block Damping Inverse Power Method,"We propose an eigensolver and the corresponding package, GCGE, for solving
large scale eigenvalue problems. This method is the combination of damping
idea, subspace projection method and inverse power method with dynamic shifts.
To reduce the dimensions of projection subspaces, a moving mechanism is
developed when the number of desired eigenpairs is large. The numerical
methods, implementing techniques and the structure of the package are
presented. Plenty of numerical results are provided to demonstrate the
efficiency, stability and scalability of the concerned eigensolver and the
package GCGE for computing many eigenpairs of large symmetric matrices arising
from applications.",2111.06552v1
2021-11-25,Continuity and topological structural stability for nonautonomous random attractors,"In this work, we study continuity and topological structural stability of
attractors for nonautonomous random differential equations obtained by small
bounded random perturbations of autonomous semilinear problems. First, we study
existence and permanence of unstable sets of hyperbolic solutions. Then, we use
this to establish lower semicontinuity of nonautonomous random attractors and
to show that the gradient structure persists under nonautonomous random
perturbations. Finally, we apply the abstract results in a stochastic
differential equation and in a damped wave equation with a perturbation on the
damping.",2111.13006v1
2021-11-30,Determining damping terms in fractional wave equations,"This paper deals with the inverse problem of recovering an arbitrary number
of fractional damping terms in a wave equation. We develop several approaches
on uniqueness and reconstruction, some of them relying on Tauberian theorems on
the relation between the asymptotics of solutions in time and Laplace domain.
Also the possibility of additionally recovering space dependent coefficients or
initial data is discussed. The resulting methods for reconstructing
coefficients and fractional orders in these terms are tested numerically.
Additionally, we provide an analysis of the forward problem, a multiterm
fractional wave equation.",2112.00080v2
2021-12-20,Dense Coding Capacity in Correlated Noisy Channels with Weak Measurement,"Capacity of dense coding via correlated noisy channel is greater than that in
uncorrelated noisy channel. It is shown that weak measurement and reversal
measurement can make further effort to improve quantum dense coding capacity in
correlated amplitude damping channel, but this effort is very small in
correlated phase damping channel and correlated depolarizing channel.",2112.10346v1
2021-12-22,Low-frequency squeezing spectrum of a laser drivenpolar quantum emitter,"It was shown by a study of the incoherent part of the low-frequency resonance
fluorescence spectrum of the polar quantum emitter driven by semiclassical
external laser field and damped by non-squeezed vacuum reservoir that the
emitted fluorescence field is squeezed to some degree nevertheless. As was also
found, a higher degree of squeezing could, in principle, be achieved by damping
the emitter by squeezed vacuum reservoir.",2112.11809v1
2022-01-13,Cavity optomechanics in a fiber cavity: the role of stimulated Brillouin scattering,"We study the role of stimulated Brillouin scattering in a fiber cavity by
numerical simulations and a simple theoretical model and find good agreement
between experiment, simulation and theory. We also investigate an
optomechanical system based on a fiber cavity in the presence on the nonlinear
Brillouin scattering. Using simulation and theory, we show that this hybrid
optomechanical system increases optomechanical damping for low mechanical
resonance frequencies in the unresolved sideband regime. Furthermore, optimal
damping occurs for blue detuning in stark contrast to standard optomechanics.
We investigate whether this hybrid optomechanical system is capable cooling a
mechanical oscillator to the quantum ground state.",2201.04987v1
2022-01-20,Vacuum and singularity formation for compressible Euler equations with time-dependent damping,"In this paper, vacuum and singularity formation are considered for
compressible Euler equations with time-dependent damping. For $1<\gamma\leq 3$,
by constructing some new control functions ingeniously, we obtain the lower
bounds estimates on density for arbitrary classical solutions. Basing on these
lower estimates, we succeed in proving the singular formation theorem for all
$\lambda$, which was open in [1] for some cases.Moreover, the singularity
formation of the compressible Euler equations when $\gamma=3$ is investigated,
too.",2201.07957v1
2022-01-22,Absorption of charged particles in Perfectly-Matched-Layers by optimal damping of the deposited current,"Perfectly-Matched Layers (PML) are widely used in Particle-In-Cell
simulations, in order to absorb electromagnetic waves that propagate out of the
simulation domain. However, when charged particles cross the interface between
the simulation domain and the PMLs, a number of numerical artifacts can arise.
In order to mitigate these artifacts, we introduce a new PML algorithm whereby
the current deposited by the macroparticles in the PML is damped by an
analytically-derived, optimal coefficient. The benefits of this new algorithm
is illustrated in practical simulations.",2201.09084v2
2022-03-19,The Equilibrium Temperature of Planets on Eccentric Orbits: Time Scales and Averages,"From estimates of the near-surface heat capacity of planets it is shown that
the thermal time scale is larger than the orbital period in the presence of a
global ocean that is well-mixed to a depth of 100 m, or of an atmosphere with a
pressure of several tens of bars. As a consequence, the temperature
fluctuations of such planets on eccentric orbits are damped. The average
temperature should be calculated by taking the temporal mean of the irradiation
over an orbit, which increases with $1/\sqrt{1-e^2}$. This conclusion is
independent of the orbital distance and valid for Sun-like stars; the damping
is even stronger for low-mass main sequence hosts.",2203.11723v1
2022-03-31,Long-time dynamical behavior for a piezoelectric system with magnetic effect and nonlinear dampings,"This paper is concerned with the long-time dynamical behavior of a
piezoelectric system with magnetic effect, which has nonlinear damping terms
and external forces with a parameter. At first, we use the nonlinear semigroup
theory to prove the well-posedness of solutions. Then, we investigate the
properties of global attractors and the existence of exponential attractors.
Finally, the upper semicontinuity of global attractors has been investigated.",2203.16736v1
2022-04-04,Exponential ergodicity for damping Hamiltonian dynamics with state-dependent and non-local collisions,"In this paper, we investigate the exponential ergodicity in a
Wasserstein-type distance for a damping Hamiltonian dynamics with
state-dependent and non-local collisions, which indeed is a special case of
piecewise deterministic Markov processes while is very popular in numerous
modelling situations including stochastic algorithms. The approach adopted in
this work is based on a combination of the refined basic coupling and the
refined reflection coupling for non-local operators. In a certain sense, the
main result developed in the present paper is a continuation of the counterpart
in \cite{BW2022} on exponential ergodicity of stochastic Hamiltonian systems
with L\'evy noises and a complement of \cite{BA} upon exponential ergodicity
for Andersen dynamics with constant jump rate functions.",2204.01372v1
2022-04-08,Effect of Tamm surface states on hot electron generation and Landau damping in nanostructures metal-semiconductor,"The hot electron generation in plasmonic nanoparticles is the key to
efficient plasmonic photocatalysis. In the paper, we study theoretically for
the first time the effect of Tamm states (TSs) at the interface
metal-semiconductor on hot electron generation and Landau damping (LD) in metal
nanoparticles. TSs can lead to resonant hot electron generation and to the LD
rate enhanced by several times. The resonant hot electron generation is
reinforced by the transition absorption due to the jump of the permittivity at
the metal-semiconductor interface.",2204.04021v1
2022-04-11,Certified Reduced Basis Method for the Damped Wave Equations on Networks,"In this paper we present a reduced basis method which yields
structure-preservation and a tight a posteriori error bound for the simulation
of the damped wave equations on networks. The error bound is based on the
exponential decay of the energy inside the system and therefore allows for
sharp bounds without the need of regularization parameters. The fast
convergence of the reduced solution to the truth solution as well as the
tightness of the error bound are verified numerically using an academic network
as example.",2204.05010v1
2022-04-27,Spectrum of the wave equation with Dirac damping on a non-compact star graph,"We consider the wave equation on non-compact star graphs, subject to a
distributional damping defined through a Robin-type vertex condition with
complex coupling. It is shown that the non-self-adjoint generator of the
evolution problem admits an abrupt change in its spectral properties for a
special coupling related to the number of graph edges. As an application, we
show that the evolution problem is highly unstable for the critical couplings.
The relationship with the Dirac equation in non-relativistic quantum mechanics
is also mentioned.",2204.12747v1
2022-04-27,Dependence on the thermodynamic state of self-diffusion of pseudo hard-spheres,"Self-diffusion, $D$, in a system of particles that interact with a pseudo
hard sphere potential is analyzed. Coupling with a solvent is represented by a
Langevin thermostat, characterized by the damping time $t_d$. The hypotheses
that $D=D_0 \varphi$ is proposed, where $D_0$ is the small concentration
diffusivity and $\varphi$ is a thermodynamic function that represents the
effects of interactions as concentration is increased. Molecular dynamics
simulations show that different values of the noise intensity modify $D_0$ but
do not modify $\varphi$. This result is consistent with the assumption that
$\varphi$ is a thermodynamic function, since the thermodynamic state is not
modified by the presence of damping and noise.",2204.12969v1
2022-04-29,Plasmon damping rates in Coulomb-coupled two-dimensional layers in a heterostructure,"The Coulomb excitations of charge density oscillation are calculated for a
double-layer heterostructure. Specifically, we consider two-dimensional (2D)
layers of silicene and graphene on a substrate. From the obtained surface
response function, we calculated the plasmon dispersion relations which
demonstrate the way in which the Coulomb coupling renormalizes the plasmon
frequencies. Additionally, we present a novel result for the damping rates of
the plasmons in this Coulomb coupled heterostructure and compare these results
as the separation between layers is varied.",2205.00053v1
2022-05-08,A regularity criterion for a 3D tropical climate model with damping,"In this paper we deal with the 3D tropical climate model with damping terms
in the equation of the barotropic mode $u$ and in the equation of the first
baroclinic mode $v$ of the velocity, and we establish a regularity criterion
for this system thanks to which the local smooth solution $(u, v, \theta)$ can
actually be extended globally in time.",2205.03841v3
2022-06-04,Radiation backreaction in axion electrodynamics,"Energy-momentum conservation of classical axion-electrodynamics is carefully
analyzed in the Hamiltonian formulation of the theory. The term responsible for
the energy transfer between the electromagnetic and the axion sectors is
identified. As a special application the axion-to-light Primakoff-process in
the background of a static magnetic field is worked out and the radiative
self-damping of the axion oscillations is characterized quantitatively. The
damping time turns out comparable to the age of the Universe in the preferred
axion mass range.",2206.02052v1
2022-06-07,Strong attractors for weakly damped quintic wave equation in bounded domains,"In this paper, we study the longtime dynamics for the weakly damped wave
equation with quintic non-linearity in a bounded smooth domain of
$\mathbb{R}^3.$ Based on the Strichartz estimates for the case of bounded
domains, we establish the existence of a strong global attractor in the phase
space $H^2(\Omega)\cap H^1_0(\Omega)\times H^1_0(\Omega)$. Moreover, the finite
fractal dimension of the attractor is also shown with the help of the
quasi-stable estimation.",2206.03158v1
2022-06-07,Long-time dynamics of the wave equation with nonlocal weak damping and sup-cubic nonlinearity in 3-D domains,"In this paper, we study the long-time dynamics for the wave equation with
nonlocal weak damping and sup-cubic nonlinearity in a bounded smooth domain of
$\mathbb{R}^3.$ Based on the Strichartz estimates for the case of bounded
domains, we first prove the global well-posedness of the Shatah-Struwe
solutions. Then we establish the existence of the global attractor for the
Shatah-Struwe solution semigroup by the method of contractive function.
Finally, we verify the existence of a polynomial attractor for this semigroup.",2206.03163v1
2022-06-10,Spin Pumping into Anisotropic Dirac Electrons,"We study spin pumping into an anisotropic Dirac electron system induced by
microwave irradiation to an adjacent ferromagnetic insulator theoretically. We
formulate the Gilbert damping enhancement due to the spin current flowing into
the Dirac electron system using second-order perturbation with respect to the
interfacial exchange coupling. As an illustration, we consider the anisotropic
Dirac system realized in bismuth to show that the Gilbert damping varies
according to the magnetization direction in the ferromagnetic insulator. Our
results indicate that this setup can provide helpful information on the
anisotropy of the Dirac electron system.",2206.04899v1
2022-06-17,On energy-stable and high order finite element methods for the wave equation in heterogeneous media with perfectly matched layers,"This paper presents a stable finite element approximation for the acoustic
wave equation on second-order form, with perfectly matched layers (PML) at the
boundaries. Energy estimates are derived for varying PML damping for both the
discrete and the continuous case. Moreover, a priori error estimates are
derived for constant PML damping. Most of the analysis is performed in Laplace
space. Numerical experiments in physical space validate the theoretical
results.",2206.08507v1
2022-06-20,Harmonic Oscillators of Mathematical Biology: Many Faces of a Predator-Prey Model,"We show that a number of models in virus dynamics, epidemiology and plant
biology can be presented as ``damped"" versions of the Lotka-Volterra
predator-prey model, by analogy to the damped harmonic oscillator. The analogy
deepens with the use of Lyapunov functions, which allow us to characterize
their dynamics and even make some estimates.",2206.09561v1
2022-06-21,Phase-covariant mixtures of non-unital qubit maps,"We analyze convex combinations of non-unital qubit maps that are
phase-covariant. In particular, we consider the behavior of maps that combine
amplitude damping, inverse amplitude damping, and pure dephasing. We show that
mixing non-unital channels can result in restoring the unitality, whereas
mixing commutative maps can lead to non-commutativity. For the convex
combinations of Markovian semigroups, we prove that classical uncertainties
cannot break quantum Markovianity. Moreover, contrary to the Pauli channel
case, the semigroup can be recovered only by mixing two other semigroups.",2206.10742v1
2022-07-01,Stabilization results of a Lorenz piezoelectric beam with partial viscous dampings,"In this paper, we investigate the stabilization of a one-dimensional Lorenz
piezoelectric (Stretching system) with partial viscous dampings. First, by
using Lorenz gauge conditions, we reformulate our system to achieve the
existence and uniqueness of the solution. Next, by using General criteria of
Arendt-Batty, we prove the strong stability in different cases. Finally, we
prove that it is sufficient to control the stretching of the center-line of the
beam in x-direction to achieve the exponential stability. Numerical results are
also presented to validate our theoretical result.",2207.00488v1
2022-07-06,Quantum Decomposition Algorithm For Master Equations of Stochastic Processes: The Damped Spin Case,"We introduce a quantum decomposition algorithm (QDA) that decomposes the
problem $\frac{\partial \rho}{\partial t}=\mathcal{L}\rho=\lambda \rho$ into a
summation of eigenvalues times phase-space variables. One interesting feature
of QDA stems from its ability to simulate damped spin systems by means of pure
quantum harmonic oscillators adjusted with the eigenvalues of the original
eigenvalue problem. We test the proposed algorithm in the case of undriven
qubit with spontaneous emission and dephasing.",2207.02755v3
2022-07-25,Geometric modelling of polycrystalline materials: Laguerre tessellations and periodic semi-discrete optimal transport,"In this paper we describe a fast algorithm for generating periodic RVEs of
polycrystalline materials. In particular, we use the damped Newton method from
semi-discrete optimal transport theory to generate 3D periodic Laguerre
tessellations (or power diagrams) with cells of given volumes. Complex,
polydisperse RVEs with up to 100,000 grains of prescribed volumes can be
created in a few minutes on a standard laptop. The damped Newton method relies
on the Hessian of the objective function, which we derive by extending recent
results in semi-discrete optimal transport theory to the periodic setting.",2207.12036v1
2022-07-27,Subsonic time-periodic solution to compressible Euler equations with damping in a bounded domain,"In this paper, we consider the one-dimensional isentropic compressible Euler
equations with linear damping $\beta(t,x)\rho u$ in a bounded domain, which can
be used to describe the process of compressible flows through a porous
medium.~And the model is imposed a dissipative subsonic time-periodic boundary
condition.~Our main results reveal that the time-periodic boundary can trigger
a unique subsonic time-periodic smooth solution which is stable under small
perturbations on initial data. Moreover, the time-periodic solution possesses
higher regularity and stability provided a higher regular boundary condition.",2207.13433v1
2022-09-10,Landau damping on the torus for the Vlasov-Poisson system with massless electrons,"This paper studies the nonlinear Landau damping on the torus $\mathbb{T}^d$
for the Vlasov-Poisson system with massless electrons (VPME). We consider
solutions with analytic or Gevrey ($\gamma > 1/3$) initial data, close to a
homogeneous equilibrium satisfying a Penrose stability condition. We show that
for such solutions, the corresponding density and force field decay
exponentially fast as time goes to infinity. This work extends the results for
Vlasov-Poisson on the torus to the case of ions and, more generally, to
arbitrary analytic nonlinear couplings.",2209.04676v2
2022-09-25,Polynomial mixing of a stochastic wave equation with dissipative damping,"We study the long time statistics of a class of semi--linear wave equations
modeling the motions of a particle suspended in continuous media while being
subjected to random perturbations via an additive Gaussian noise. By comparison
with the nonlinear reaction settings, of which the solutions are known to
possess geometric ergodicity, we find that, under the impact of nonlinear
dissipative damping, the mixing rate is at least polynomial of any order. This
relies on a combination of Lyapunov conditions, the contracting property of the
Markov transition semigroup as well as the notion of $d$--small sets.",2209.12151v2
2022-09-30,A Lyapunov approach for the exponential stability of a damped Timoshenko beam,"In this technical note, we consider the stability properties of a viscously
damped Timoshenko beam equation with spatially varying parameters. With the
help of the port-Hamiltonian framework, we first prove the existence of
solutions and show, by an appropriate Lyapunov function, that the system is
exponentially stable and has an explicit decay rate. The explicit exponential
bound is computed for an illustrative example of which we provide some
numerical simulations.",2209.15281v1
2022-11-01,Well-posedness and strong attractors for a beam model with degenerate nonlocal strong damping,"This paper is devoted to initial-boundary value problem of an extensible beam
equation with degenerate nonlocal energy damping in
$\Omega\subset\mathbb{R}^n$: $u_{tt}-\kappa\Delta u+\Delta^2u-\gamma(\Vert
\Delta u\Vert^2+\Vert u_t\Vert^2)^q\Delta u_t+f(u)=0$. We prove the global
existence and uniqueness of weak solutions, which gives a positive answer to an
open question in [24]. Moreover, we establish the existence of a strong
attractor for the corresponding weak solution semigroup, where the ``strong""
means that the compactness and attractiveness of the attractor are in the
topology of a stronger space $\mathcal{H}_{\frac{1}{q}}$.",2211.00287v3
2022-11-18,Energy decay estimates for an axially travelling string damped at one end,"We study the small vibrations of an axially travelling string with a
dashpoint damping at one end. The string is modelled by a wave equation in a
time-dependent interval with two endpoints moving at a constant speed $v$. For
the undamped case, we obtain a conserved functional equivalent to the energy of
the solution. We derive precise upper and lower estimates for the exponential
decay of the energy with explicit constants. These estimates do not seem to be
reported in the literature even for the non-travelling case $v=0$.",2211.10537v1
2022-12-01,The viscous damping of three dimensional spherical gas bubble inside unbounded compressible liquid,"The present paper considers a homogeneous bubble inside an unbounded
polytropic compressible liquid with viscosity. The system is governed by the
Navier-Stokes equation with free boundary which is determined by the kinematic
and dynamic boundary conditions on the bubble-liquid interface. The global
existence of solution is proved, and the $\dot{H}^1$ asymptotic stability of
the spherical equilibrium in terms of viscous damping together with a explicit
decay rate is given in bare energy methods.",2212.00299v1
2022-12-27,Stabilization of the Kawahara-Kadomtsev-Petviashvili equation with time-delayed feedback,"Results of stabilization for the higher order of the Kadomtsev-Petviashvili
equation are presented in this manuscript. Precisely, we prove with two
different approaches that under the presence of a damping mechanism and an
internal delay term (anti-damping) the solutions of the
Kawahara-Kadomtsev-Petviashvili equation are locally and globally exponentially
stable. The main novelty is that we present the optimal constant, as well as
the minimal time, that ensures that the energy associated with this system goes
to zero exponentially.",2212.13552v1
2023-02-17,Control of magnon-photon coupling by spin torque,"We demonstrate the influence of damping and field-like torques in the
magnon-photon coupling process by classically integrating the generalized
Landau-Lifshitz-Gilbert equation with RLC equation in which a phase correlation
between dynamic magnetization and microwave current through combined Amp\`ere
and Faraday effects are considered. We show that the gap between two hybridized
modes can be controlled in samples with damping parameter in the order of
$10^{-3}$ by changing the direction of the dc current density $J$ if a certain
threshold is reached. Our results suggest that an experimental realization of
the proposed magnon-photon coupling control mechanism is feasible in yttrium
iron garnet/Pt hybrid structures.",2302.08910v1
2023-02-23,Hopf-Like Bifurcation in a Wave Equation at a Removable Singularity,"It is shown that a one-dimensional damped wave equation with an odd time
derivative nonlinearity exhibits small amplitude bifurcating time periodic
solutions, when the bifurcation parameter is the linear damping coefficient is
positive and accumulates to zero. The upshot is that the singularity of the
linearized operator at criticality which stems from the well known small
divisor problem for the wave operator, is entirely removed without the need to
exclude parameters via Diophantine conditions, nor the use of accelerated
convergence schemes. Only the contraction mapping principle is used.",2302.12092v2
2023-03-02,Spin Pumping into Carbon Nanotubes,"We theoretically study spin pumping from a ferromagnetic insulator (FI) into
a carbon nanotube (CNT). By employing the bosonization method, we formulate the
Gilbert damping induced by the FI/CNT junction, which can be measured by
ferromagnetic resonance. We show that the increase in the Gilbert damping has a
temperature dependence characteristic of a Luttinger liquid and is highly
sensitive to the Luttinger parameter of the spin sector for a clean interface.
We also discuss the experimental relevance of our findings based on numerical
estimates, using realistic parameters.",2303.01343v2
2023-03-11,Control estimates for 0th order pseudodifferential operators,"We introduce the control conditions for 0th order pseudodifferential
operators $\mathbf{P}$ whose real parts satisfy the Morse--Smale dynamical
condition. We obtain microlocal control estimates under the control conditions.
As a result, we show that there are no singular profiles in the solution to the
evolution equation $(i\partial_t-\mathbf{P})u=f$ when $\mathbf{P}$ has a
damping term that satisfies the control condition and $f\in C^{\infty}$. This
is motivated by the study of a microlocal model for the damped internal waves.",2303.06443v2
2023-03-24,Exponential decay estimates for semilinear wave-type equations with time-dependent time delay,"In this paper, we analyze a semilinear damped second order evolution equation
with time-dependent time delay and time-dependent delay feedback coefficient.
The nonlinear term satisfies a local Lipschitz continuity assumption. Under
appropriate conditions, we prove well-posedness and exponential stability of
our model for small initial data. Our arguments combine a Lyapunov functional
approach with some continuity arguments. Moreover, as an application of our
abstract results, the damped wave equation with a source term and delay
feedback is analyzed.",2303.14208v1
2023-03-25,Existence and regularity of global attractors for a Kirchhoff wave equation with strong damping and memory,"This paper is concerned with the existence and regularity of global attractor
$\mathcal A$ for a Kirchhoff wave equation with strong damping and memory in
the weighted time-dependent spaces $\mathcal H$ and $\mathcal H^{1}$,
respectively. In order to obtain the existence of $\mathcal A$, we mainly use
the energy method in the priori estimations, and then verify the asymptotic
compactness of the semigroup by the method of contraction function. Finally, by
decomposing the weak solutions into two parts and some elaborate calculations,
we prove the regularity of $\mathcal A$.",2303.14387v1
2023-03-27,Linear Landau damping for a two-species Vlasov-Poisson system for electrons and ions,"This paper concerns the linear Landau damping for the two species
Vlasov-Poisson system for ions and electrons near Penrose stable equilibria.
The result is an extension of the result on the one species Vlasov-Poisson
equation by Mouhout and Villani. Different from their work we do not describe
the ions as a background species but as a species which is also described by a
separate Vlasov equation. We show an exponential decay of the electric energy
for the linearised system near Penrose stable equilibria.",2303.14981v2
2023-03-28,Role of intersublattice exchange interaction on ultrafast longitudinal and transverse magnetization dynamics in Permalloy,"We report about element specific measurements of ultrafast demagnetization
and magnetization precession damping in Permalloy (Py) thin films.
Magnetization dynamics induced by optical pump at $1.5$eV is probed
simultaneously at the $M_{2,3}$ edges of Ni and Fe with High order Harmonics
for moderate demagnetization rates (less than $50$%). The role of the
intersublattice exchange interaction on both longitudinal and transverse
dynamics is analyzed with a Landau Lifshitz Bloch description of
ferromagnetically coupled Fe and Ni sublattices. It is shown that the
intersublattice exchange interaction governs the dissipation during
demagnetization as well as precession damping of the magnetization vector.",2303.15837v1
2023-03-31,Polynomial Mixing for a Weakly Damped Stochastic Nonlinear Schrödinger Equation,"This paper is devoted to proving the polynomial mixing for a weakly damped
stochastic nonlinear Schr\""{o}dinger equation with additive noise on a 1D
bounded domain. The noise is white in time and smooth in space. We consider
both focusing and defocusing nonlinearities, respectively, with exponents of
the nonlinearity $\sigma\in[0,2)$ and $\sigma\in[0,\infty)$ and prove the
polynomial mixing which implies the uniqueness of the invariant measure by
using a coupling method.",2303.18082v1
2023-04-19,Inviscid damping of monotone shear flows for 2D inhomogeneous Euler equation with non-constant density in a finite channel,"We prove the nonlinear inviscid damping for a class of monotone shear flows
with non-constant background density for the two-dimensional ideal
inhomogeneous fluids in $\mathbb{T}\times [0,1]$ when the initial perturbation
is in Gevrey-$\frac{1}{s}$ ($\frac{1}{2}<s<1$) class with compact support.",2304.09841v2
2023-05-07,Nonexistence of global weak solutions to semilinear wave equations involving time-dependent structural damping terms,"We consider a semilinear wave equation involving a time-dependent structural
damping term of the form
$\displaystyle\frac{1}{{(1+t)}^{\beta}}(-\Delta)^{\sigma/2} u_t$. Our results
show the influence of the parameters $\beta,\sigma$ on the nonexistence of
global weak solutions under assumptions on the given system data.",2305.04278v1
2023-05-15,Blow-up phenomena for a class of extensible beam equations,"In this paper, we investigate the initial boundary value problem of the
following nonlinear extensible beam equation with nonlinear damping term $$u_{t
t}+\Delta^2 u-M\left(\|\nabla u\|^2\right) \Delta u-\Delta
u_t+\left|u_t\right|^{r-1} u_t=|u|^{p-1} u$$ which was considered by Yang et
al. (Advanced Nonlinear Studies 2022; 22:436-468). We consider the problem with
the nonlinear damping and establish the finite time blow-up of the solution for
the initial data at arbitrary high energy level, including the estimate lower
and upper bounds of the blowup time. The result provides some affirmative
answer to the open problems given in (Advanced Nonlinear Studies 2022;
22:436-468).",2305.08398v1
2023-06-08,Vanishing of long time average p-enstrophy dissipation rate in the inviscid limit of the 2D damped Navier-Stokes equations,"In 2007, Constantin and Ramos proved a result on the vanishing long time
average enstrophy dissipation rate in the inviscid limit of the 2D damped
Navier-Stokes equations. In this work, we prove a generalization of this for
the p-enstrophy, sequences of distributions of initial data and sequences of
strongly converging right-hand sides. We simplify their approach by working
with invariant measures on the global attractors which can be characterized via
bounded complete solution trajectories. Then, working on the level of
trajectories allows us to directly employ some recent results on strong
convergence of the vorticity in the inviscid limit.",2306.05081v1
2023-06-13,Stability of asymptotically Hamiltonian systems with damped oscillatory and stochastic perturbations,"A class of asymptotically autonomous systems on the plane with oscillatory
coefficients is considered. It is assumed that the limiting system is
Hamiltonian with a stable equilibrium. The effect of damped multiplicative
stochastic perturbations of white noise type on the stability of the system is
discussed. It is shown that different long-term asymptotic regimes for
solutions are admissible in the system and the stochastic stability of the
equilibrium depends on the realized regime. In particular, we show that stable
phase locking is possible in the system due to decaying stochastic
perturbations. The proposed analysis is based on a combination of the averaging
technique and the construction of stochastic Lyapunov functions.",2306.07694v1
2023-06-16,Algorithm MGB to solve highly nonlinear elliptic PDEs in $\tilde{O}(n)$ FLOPS,"We introduce Algorithm MGB (Multi Grid Barrier) for solving highly nonlinear
convex Euler-Lagrange equations. This class of problems includes many highly
nonlinear partial differential equations, such as $p$-Laplacians. We prove
that, if certain regularity hypotheses are satisfied, then our algorithm
converges in $\tilde{O}(1)$ damped Newton iterations, or $\tilde{O}(n)$ FLOPS,
where the tilde indicates that we neglect some polylogarithmic terms. This the
first algorithm whose running time is proven optimal in the big-$\tilde{O}$
sense. Previous algorithms for the $p$-Laplacian required $\tilde{O}(\sqrt{n})$
damped Newton iterations or more.",2306.10183v1
2023-06-28,Global solutions and blow-up for the wave equation with variable coefficients: II. boundary supercritical source,"In this paper, we consider the wave equation with variable coefficients and
boundary damping and supercritical source terms. The goal of this work is
devoted to prove the local and global existence, and classify decay rate of
energy depending on the growth near zero on the damping term. Moreover, we
prove the blow-up of the weak solution with positive initial energy as well as
nonpositive initial energy.",2306.15897v4
2023-07-24,On the stability of a double porous elastic system with visco-porous dampings,"In this paper we consider a one dimensional elastic system with double
porosity structure and with frictional damping in both porous equations. We
introduce two stability numbers $\chi_{0}$ and $\chi_{1}$ and prove that the
solution of the system decays exponentially provided that $\chi_{0}=0$ and
$\chi_{1}\neq0.$ Otherwise, we prove the lack of exponential decay. Our results
improve the results of \cite{Bazarra} and \cite{Nemsi}.",2307.12690v1
2023-07-27,Best Ulam constants for damped linear oscillators with variable coefficients,"This study uses an associated Riccati equation to study the Ulam stability of
non-autonomous linear differential vector equations that model the damped
linear oscillator. In particular, the best (minimal) Ulam constants for these
non-autonomous linear differential vector equations are derived. These robust
results apply to vector equations with solutions that blow up in finite time,
as well as to vector equations with solutions that exist globally on
$(-\infty,\infty)$. Illustrative, non-trivial examples are presented,
highlighting the main results.",2307.15103v1
2023-07-29,An inverse problem for the fractionally damped wave equation,"We consider an inverse problem for a Westervelt type nonlinear wave equation
with fractional damping. This equation arises in nonlinear acoustic imaging,
and we show the forward problem is locally well-posed. We prove that the smooth
coefficient of the nonlinearity can be uniquely determined, based on the
knowledge of the source-to-solution map and a priori knowledge of the
coefficient in an arbitrarily small subset of the domain. Our approach relies
on a second order linearization as well as the unique continuation property of
the spectral fractional Laplacian.",2307.16065v1
2023-08-02,Blow-up and lifespan estimate for the generalized tricomi equation with the scale-invariant damping and time derivative nonlinearity on exterior domain,"The article is devoted to investigating the initial boundary value problem
for the damped wave equation in the scale-invariant case with time-dependent
speed of propagation on the exterior domain. By presenting suitable multipliers
and applying the test-function technique, we study the blow-up and the lifespan
of the solutions to the problem with derivative-type nonlinearity
  $ \d u_{tt}-t^{2m}\Delta u+\frac{\mu}{t}u_t=|u_t|^p, \quad \mbox{in}\
\Omega^{c}\times[1,\infty),$ that we associate with appropriate small initial
data.",2308.01272v2
2023-08-03,Gravitational Wave Heating,"It was shown in previous work that when a gravitational wave (GW) passes
through a viscous shell of matter the magnitude of the GW will be damped and
there are astrohysical circumstances in which the damping is almost complete.
The energy transfer from the GWs to the fluid will increase its temperature. We
construct a model for this process and obtain an expression for the temperature
distribution inside the shell in terms of spherical harmonics. Further, it is
shown that this effect is astrophysically significant: a model problem is
constructed for which the temperature increase is of order $10^6{}^\circ$K.",2308.01615v2
2023-08-08,Stabilization of piezoelectric beam with Coleman-Gurtin or Gurtin-Pipkin thermal law and under Lorenz gauge condition,"In this paper, we present the analysis of stability for a piezoelectric beam
subject to a thermal law (Coleman-Gurtin or Gurtin-Pipkin thermal law) adding
some viscous damping mechanism to the electric field in $x-$direction and
$z-$direction, and we discuss several cases. Then, there is no need to control
the electrical field components in $x$-direction and $z-$ direction to
establish an exponential decay of solutions when the beam is subjected to a
Coleman-Gurtin law, otherwise a polynomial stability is established with
Gurtin-Pipkin thermal law in case when the electrical field components are
damped.",2308.04231v2
2023-08-11,Well-posedness and global attractor for wave equation with nonlinear damping and super-cubic nonlinearity,"In the paper, we study the semilinear wave equation involving the nonlinear
damping $g(u_t) $ and nonlinearity $f(u)$. Under the wider ranges of exponents
of $g$ and $f$, the well-posedness of the weak solution is achieved by
establishing a priori space-time estimates. Then, the existence of the global
attractor in the naturally phase space $H^1_0(\Omega)\times L^2(\Omega)$ is
obtained. Moreover, we prove that the global attrator is regular, that is, the
global attractor is a bounded subset of $(H^2(\Omega)\cap H^1_0(\Omega))\times
H^1_0(\Omega)$.",2308.06208v1
2023-08-16,Stability for degenerate wave equations with drift under simultaneous degenerate damping,"In this paper we study the stability of two different problems. The first one
is a one-dimensional degenerate wave equation with degenerate damping,
incorporating a drift term and a leading operator in non-divergence form. In
the second problem we consider a system that couples degenerate and
non-degenerate wave equations, connected through transmission, and subject to a
single dissipation law at the boundary of the non-degenerate equation. In both
scenarios, we derive exponential stability results.",2308.08645v3
2023-09-02,Existence and nonexistence of global solutions for time-dependent damped NLS equations,"We investigate the Cauchy problem for the nonlinear Schr\""odinger equation
with a time-dependent linear damping term. Under non standard assumptions on
the loss dissipation, we prove the blow-up in the inter-critical regime, and
the global existence in the energy subcritical case. Our results generalize and
improve the ones in [9, 11, 21].",2309.00849v1
2023-09-04,On the small-mass limit for stationary solutions of stochastic wave equations with state dependent friction,"We investigate the convergence, in the small mass limit, of the stationary
solutions of a class of stochastic damped wave equations, where the friction
coefficient depends on the state and the noisy perturbation if of
multiplicative type. We show that the Smoluchowski-Kramers approximation that
has been previously shown to be true in any fixed time interval, is still valid
in the long time regime. Namely we prove that the first marginals of any
sequence of stationary solutions for the damped wave equation converge to the
unique invariant measure of the limiting stochastic quasilinear parabolic
equation. The convergence is proved with respect to the Wasserstein distance
associated with the $H^{-1}$ norm.",2309.01549v1
2023-09-09,Finite-dimensionality of attractors for wave equations with degenerate nonlocal damping,"In this paper we study the fractal dimension of global attractors for a class
of wave equations with (single-point) degenerate nonlocal damping. Both the
equation and its linearization degenerate into linear wave equations at the
degenerate point and the usual approaches to bound the dimension of the
entirety of attractors do not work directly. Instead, we develop a new process
concerning the dimension near the degenerate point individually and show the
finite dimensionality of the attractor.",2309.04712v2
2023-09-19,The Raman gap and collisional absorption,"One of the long-standing puzzles observed in many laser-plasma experiments is
the gap in the Raman backscattering spectrum. This gap is characterized by the
absence of backscattered light between some critical wavelength and twice the
incident laser wavelength. The latter is associated with the absolute Raman
instability from the quarter-critical density surface. Supported by
particle-in-cell (PIC) simulations, it is suggested that the gap can result
from the collisional damping of the backscattered light. A linear analysis of
the competition between the Raman growth rate and the damping rate in a
non-homogenous plasma predicts the gap's existence and width as a function of
the system's parameters. The theory is compared with the PIC simulations and
past experiments.",2309.10366v1
2023-09-21,Inverse problems for a quasilinear strongly damped wave equation arising in nonlinear acoustics,"We consider inverse problems for a Westervelt equation with a strong damping
and a time-dependent potential $q$. We first prove that all boundary
measurements, including the initial data, final data, and the lateral boundary
measurements, uniquely determine $q$ and the nonlinear coefficient $\beta$. The
proof is based on complex geometric optics construction and the approach
proposed by Isakov. Further, by considering fundamental solutions supported in
a half-space constructed by H\""ormander, we prove that with vanishing initial
conditions the Dirichlet-to-Neumann map determines $q$ and $\beta$.",2309.11775v1
2023-09-28,On inverse problems for a strongly damped wave equation on compact manifolds,"We consider a strongly damped wave equation on compact manifolds, both with
and without boundaries, and formulate the corresponding inverse problems. For
closed manifolds, we prove that the metric can be uniquely determined, up to an
isometry, from the knowledge of the source-to-solution map. Similarly, for
manifolds with boundaries, we prove that the metric can be uniquely determined,
up to an isometry, from partial knowledge of the Dirichlet-to-Neumann map. The
key point is to retrieve the spectral information of the Laplace-Beltrami
operator, from the Laplace transform of the measurements. Further we show that
the metric can be determined up to an isometry, using a single measurement in
both scenarios.",2309.16182v1
2023-10-10,Emerging Spin-Orbit Torques in Low Dimensional Dirac Materials,"We report a theoretical description of novel spin-orbit torque components
emerging in two-dimensional Dirac materials with broken inversion symmetry. In
contrast to usual metallic interfaces where field-like and damping-like torque
components are competing, we find that an intrinsic damping-like torque which
derives from all Fermi-sea electrons can be simultaneously enhanced along with
the field-like component. Additionally, hitherto overlooked torque components
unique to Dirac materials, emerge from the coupling between spin and pseudospin
degrees of freedom. These torques are found to be resilient to disorder and
could enhance the magnetic switching performance of nearby magnets.",2310.06447v1
2023-10-22,The residual flow in well-optimized stellarators,"The gyrokinetic theory of the residual flow, in the electrostatic limit, is
revisited, with optimized stellarators in mind. We consider general initial
conditions for the problem, and identify cases that lead to a non-zonal
residual electrostatic potential, i.e. one having a significant component that
varies within a flux surface. We investigate the behavior of the ``intermediate
residual'' in stellarators, a measure of the flow that remains after geodesic
acoustic modes have damped away, but before the action of the slower damping
that is caused by unconfined particle orbits. The case of a quasi-isodynamic
stellarator is identified as having a particularly large such residual, owing
to the small orbit width achieved by optimization.",2310.14218v1
2023-10-26,Efficient Numerical Algorithm for Large-Scale Damped Natural Gradient Descent,"We propose a new algorithm for efficiently solving the damped Fisher matrix
in large-scale scenarios where the number of parameters significantly exceeds
the number of available samples. This problem is fundamental for natural
gradient descent and stochastic reconfiguration. Our algorithm is based on
Cholesky decomposition and is generally applicable. Benchmark results show that
the algorithm is significantly faster than existing methods.",2310.17556v1
2023-11-09,Exponential convergence to steady-states for trajectories of a damped dynamical system modelling adhesive strings,"We study the global well-posedness and asymptotic behavior for a semilinear
damped wave equation with Neumann boundary conditions, modelling a
one-dimensional linearly elastic body interacting with a rigid substrate
through an adhesive material. The key feature of of the problem is that the
interplay between the nonlinear force and the boundary conditions allows for a
continuous set of equilibrium points. We prove an exponential rate of
convergence for the solution towards a (uniquely determined) equilibrium point.",2311.05295v1
2023-11-29,On the exponential stability of uniformly damped wave equations,"We study damped wave propagation problems phrased as abstract evolution
equations in Hilbert spaces. Under some general assumptions, including a
natural compatibility condition for initial values, we establish exponential
decay estimates for all mild solutions using the language and tools of Hilbert
complexes. This framework turns out strong enough to conduct our analysis but
also general enough to include a number of interesting examples. Some of these
are briefly discussed. By a slight modification of the main arguments, we also
obtain corresponding decay results for numerical approximations obtained by
compatible discretization strategies.",2311.18084v1
2023-12-01,Semilinear wave inequalities with double damping and potential terms on Riemannian Manifolds,"We study a semilinear wave inequality with double damping on a complete
noncompact Riemannian manifold. The considered problem involves a potential
function $V$ depending on the space variable in front of the power nonlinearity
and an inhomogeneous term $W$ depending on both time and space variables.
Namely, we establish sufficient conditions for the nonexistence of weak
solutions in both cases: $W\equiv 0$ and $W\not\equiv 0$. The obtained
conditions depend on the parameters of the problem as well as the geometry of
the manifold. Some special cases of manifolds, and of $V$ and $W$ are discussed
in detail.",2312.00617v1
2023-12-29,On damping a control system of arbitrary order with global aftereffect on a tree,"We study a problem of damping a control system described by
functional-differential equations of natural order $n$ and neutral type with
non-smooth complex coefficients on an arbitrary tree with global delay. The
latter means that the delay propagates through internal vertices of the tree.
Minimization of the energy functional of the system leads to a variational
problem. We establish its equivalence to a certain self-adjoint boundary value
problem on the tree for equations of order $2n$ with nonlocal quasi-derivatives
and multidirectional shifts of the argument, as well as Kirchhoff-type
conditions emerging at the internal vertices. The unique solvability of both
problems is proved.",2312.17592v1
2024-01-11,Weak collision effect on nonlinear Landau damping for the Vlasov-Poisson-Fokker-Planck system,"We investigate the impact of weak collisions on Landau damping in the
Vlasov-Poisson-Fokker-Planck system on a torus, specifically focusing on its
proximity to a Maxwellian distribution. In the case where the Gevrey index
satisfies $\frac{1}{s}<3$, we establish the global stability and enhanced
dissipation of small initial data, which remain unaffected by the small
diffusion coefficient $\nu$. For Gevrey index $\frac{1}{s}\ge3$, we prove the
global stability and enhanced dissipation of initial data, whose size is on the
order of $O(\nu^a)$ for any $a>\frac{1-3s}{3-3s}$. Our analysis provides
insights into the effects of phase mixing, enhanced dissipation, and plasma
echoes.",2401.05601v3
2024-01-23,Revisit on global existence of solutions for semilinear damped wave equations in $\mathbb{R}^N$ with noncompactly supported initial data,"In this note, we study the Cauchy problem of the semilinear damped wave
equation and our aim is the small data global existence for noncompactly
supported initial data. For this problem, Ikehata and Tanizawa [5] introduced
the energy method with the exponential-type weight function $e^{|x|^2/(1+t)}$,
which is the so-called Ikehata--Todorova--Yordanov type weight. In this note,
we suggest another weight function of the form $(1+|x|^2/(1+t))^{\lambda}$,
which allows us to treat polynomially decaying initial data and give a simpler
proof than the previous studies treating such initial data.",2401.12530v1
2024-01-24,Eigenmode analysis of the damped Jaynes-Cummings model,"The generating functions for density matrix elements of the Jaynes-Cummings
model with cavity damping are analysed in terms of their eigenmodes, which are
characterised by a specific temporal behaviour. These eigenmodes are shown to
be proportional to particular generalised hypergeometric functions. The
relative weights of these eigenmodes in the generating functions are determined
by the initial conditions of the model. These weights are found by deriving
orthogonality relations involving adjoint modes. In an example it is shown how
the time-dependent density matrix elements and the related factorial moments
can be extracted from the eigenmode decompositions of the generating functions.",2401.13348v1
2024-02-15,A comprehensive modelling and experimental approach for damped oscillations in U-tubes via Easy JavaScript Simulations,"In recent years, science simulations have become popular among educators due
to their educational usefulness, availability, and potential for increasing the
students' knowledge on scientific topics. In this paper, we introduce the
implementation of a user-friendly simulation based on Easy Java/JavaScript
Simulations (EJS) to study the problem of damped oscillations in U-tubes.
Furthermore, we illustrate various advantages associated with the capabilities
of EJS in terms of design and usability in order to encourage teachers to use
it as an educational supplement to physics laboratories.",2402.09866v1
2024-02-21,Hybrid Multi-Directional Quantum Communication Protocol,"The way a new type of state called a hybrid state, which contains more than
one degree of freedom, is used in many practical applications of quantum
communication tasks with lesser amount of resources. Similarly, our aim is here
to perform multi-quantum communication tasks in a protocol to approach quantum
information in multipurpose and multi-directional. We propose a hybrid
multi-directional six-party scheme of implementing quantum teleportation and
joint remote state preparation under the supervision of a controller via a
multi-qubit entangled state as a quantum channel with 100% success probability.
Moreover, we analytically derive the average fidelities of this hybrid scheme
under the amplitude-damping and the phase-damping noise.",2402.14043v1
2024-03-19,Damped energy-norm a posteriori error estimates for fully discrete approximations of the wave equation using C2-reconstructions,"We derive a posteriori error estimates for the the scalar wave equation
discretized in space by continuous finite elements and in time by the explicit
leapfrog scheme. Our analysis combines the idea of invoking extra
time-regularity for the right-hand side, as previously introduced in the space
semi-discrete setting, with a novel, piecewise quartic, globally
twice-differentiable time-reconstruction of the fully discrete solution. Our
main results show that the proposed estimator is reliable and efficient in a
damped energy norm. These properties are illustrated in a series of numerical
examples.",2403.12954v1
1997-07-10,"Outflow Angles, Bulk Lorentz Factors, and Kinematics of Outflows from the Cores of AGN","Outflow angles and bulk Lorentz factors for 43 sources that have proper
motions compiled by Vermeulen & Cohen (1994) are computed on the basis of
Doppler factors and observed apparent motions in the plane of the sky. These
estimates of outflow angles and bulk Lorentz factors are discussed along with
their agreement with orientation unified models of AGN. Intrinsic (i.e. rest
frame) brightness temperatures computed by using the inverse Compton and
equipartition Doppler factor are discussed along with their relevance to the
``Inverse Compton catastrophe''. Intrinsic luminosity densities and
luminosities are presented, and the role of systematic errors is discussed.
These studies are carried out using a sample of 100 compact radio sources
compiled by Ghisellini et al. (1993). Error estimates for previously computed
inverse Compton Doppler factors and equipartition Doppler factors are presented
for these sources, along with a few updates of these Doppler factor estimates.",9707124v2
2000-02-08,An eigenfunction method for particle acceleration at ultra-relativistic shocks,"We adapt and modify the eigenfunction method of computing the power-law
spectrum of particles accelerated at a relativistic shock front via the
first-order Fermi process (Kirk, J.G., Schneider, P., Astrophysical Journal
315, 425 (1987)) to apply to shocks of arbitrarily high Lorentz factor. The
power-law index of accelerated particles undergoing isotropic small-angle
scattering at an ultrarelativistic, unmagnetized shock is found to be s=4.23
+/- 0.2 (where s=d\ln f/ d\ln p, with f the Lorentz-invariant phase-space
density and p the momentum), in agreement with the results of Monte-Carlo
simulations. We present results for shocks in plasmas with different equations
of state and for Lorentz factors ranging from 5 to infinity.",0002176v1
2000-11-09,Gamma and Cosmic-Ray Tests of Special Relativity,"Lorentz symmetry violation (LSV) at Planck scale can be tested (see e.g.
physics/0003080) through ultra-high energy cosmic rays (UHECR). In a deformed
Lorentz symmetry (DLS) pattern where the effective LSV parameter varies like
the square of the momentum scale (quadratically deformed relativistic
kinematics, QDRK), a 10E-6 LSV at Planck scale would be enough to produce
observable effects on the properties of cosmic rays at the 10E20 eV scale:
absence of GZK cutoff, stability of unstable particles, lower interaction
rates, kinematical failure of any parton model and of standard formulae for
Lorentz contraction and time dilation... Its phenomenological implications are
compatible with existing data. If the effective LSV parameter is taken to vary
linearly with the momentum scale (linearly deformed relativistic kinematics,
LDRK), a LSV at Planck scale larger than 10E-7 eV seems to lead to
contradictions with data above TeV energies. Consequences are important for
high-energy gamma-ray experiments, as well as for high-energy cosmic rays and
gravitational waves.",0011181v1
2001-05-28,Energy Loss of Particles in Pulsar Radio Emission Region,"Extremely relativistic particles play an important role in various radiative
mechanisms of pulsar radio as well as high-energy emission. It is thus very
essential to estimate the Lorentz factor of these particles in the radiation
regions both observationally and theoretically. In this paper, according to the
frequency dependence of component separation and considering some radiation
processes, we obtain the Lorentz factor and its variation in the radiation
region observationally for seven multi-frequency observed pulsars. It is found
that the Lorentz factor decays substantially in the emission region, and the
decay can not be well understood by all known energy loss processes. This
result hints that there are some unknown processes which are responsible to
loosing energy effectively.",0105476v1
2002-03-14,Constraints on the Bulk Lorentz Factor of GRB 990123,"GRB 990123 was a long, complex gamma-ray burst accompanied by an extremely
bright optical flash. We present the collective constraints on the bulk Lorentz
factor for this burst based on estimates from burst kinematics, synchrotron
spectral decay, prompt radio flash observations, and prompt emission pulse
width. Combination of these constraints leads to an average bulk Lorentz factor
for GRB 990123 of Gamma_0=1000 +/- 100 which implies a baryon loading of
M_jet=8 (+17/-2) x 10^-8 Msolar. We find these constraints to be consistent
with the speculation that the optical light is emission from the reverse shock
component of the external shock. In addition, we find the implied value of
M_jet to be in accordance with theoretical estimates: the baryonic loading is
sufficiently small to allow acceleration of the outflow to Gamma > 100.",0203241v1
2003-08-12,Constraints on Lorentz Invariance Violating Quantum Gravity and Large Extra Dimensions Models using High Energy Gamma Ray Observations,"Observations of the multi-TeV spectra of the nearby BL objects Mkn 421 and
Mkn 501 exhibit the high energy cutoffs predicted to be the result of
intergalactic annihilation interactions, primarily with infrared photons having
a flux level as determined by various astronomical observations. After
correction for this absorption effect, the derived intrinsic spectra of these
multi-TeV sources can be explained within the framework of simple synchrotron
self-Compton emission models. Stecker and Glashow have shown that the existence
of such annihilations via electron-positron pair production interactions up to
an energy of 20 TeV puts strong constraints on Lorentz invariance violation.
Such constraints have important implications for Lorentz invariance violating
(LIV) quantum gravity models as well as LIV models involving large extra
dimensions. We also discuss the implications of observations of high energy
gamma-rays from the Crab Nebula on constraining quantum gravity models.",0308214v2
2003-08-25,Dynamics of Relativistic Flows,"Dynamics of relativistic outflows along the rotation axis of a Kerr black
hole is investigated using a simple model that takes into account the
relativistic tidal force of the central source as well as the Lorentz force due
to the large-scale electromagnetic field which is assumed to be present in the
ambient medium. The evolution of the speed of the flow relative to the ambient
medium is studied. In the force-free case, the resulting equation of motion
predicts rapid deceleration of the initial flow and an asymptotic relative
speed with a Lorentz factor of 2^1/2. In the presence of the Lorentz force, the
long-term relative speed of the clump tends to the ambient electrical drift
speed.",0308421v3
2004-09-29,High Energy Astrophysics Tests of Lorentz Invariance Violation,"Multi-TeV spectra of Mkn 501 and other BL Lac objects exhibit the high energy
cutoffs predicted to be the result of intergalactic annihilation interactions,
primarily with IR photons having the flux level determined by various
astrophysical observations. After correcting for such intergalactic absorption,
these spectra can be explained within the framework of synchrotron self-Compton
emission models. Stecker and Glashow have shown that the existence of this
annihilation via electron-positron pair production puts strong constriants on
Lorentz invariance violation. Such constriants have important implications for
some quantum gravity and large extra dimension models. A much smaller amount of
Lorentz invariance violation has potential implications for understanding the
spectra of ultrahigh energy cosmic rays.",0409731v1
2004-10-11,Constraints on relativistic beaming from estimators of the unbeamed flux,"We review the statistical properties of relativistic Doppler boosting
relevant for studies of relativistic jets from compact objects based on
radio--X-ray(--mass) correlations, such as that found in black-hole X-ray
binaries in the low/hard state, or the ``fundamental plane'' of Merloni, Heinz,
& DiMatteo. We show that the presence of only moderate scatter in such
relations does not necessarily imply low Lorentz factors of the jets producing
the radio emission in the samples under consideration. Applying Doppler beaming
statistics to a large sample of XRBs and AGN, we derive a limit on the width of
the Lorentz factor distribution of black holes with relativistic jets: If the
X-rays are unbeamed (e.g., if they originate in the accretion disk or in the
slower, innermost part of the jet), the width of the \beta\Gamma distribution
should be about one order of magnitude or less. If the scatter about the
``fundamental plane'' is entirely dominated by relativistic beaming, a lower
limit on the mean Lorentz factor <\beta\Gamma> > 5 can be derived. On the other
hand, if the X-rays are boosted by the same factor as the radio emission, we
show that the observed scatter cannot be reasonably explained by Doppler
boosting alone.",0410282v1
2005-01-20,Constraints from cosmic rays on non-systematic Lorentz violation,"In this article we analyze the radiation loss from a high energy cosmic ray
proton propagating in a spacetime with non-systematic Lorentz violation. From
an effective field theory perspective we illuminate flaws in previous attempts
that use threshold approaches to analyze this problem. We argue that in general
such approaches are of rather limited use when dealing with non-systematic
Lorentz violating scenarios. The main issues we raise are a) the limited
applicability of threshold energy conservation rules when translation
invariance is broken and b) the large amounts of proton particle production due
to the time dependence of the fluctuations. Ignoring particle production, we
derive a constraint on the magnitude of velocity fluctuation $|v_f|<10^{-6.5}$,
much weaker than has been previously argued. However, we show that in fact
particle production makes any such constraint completely unreliable.",0501425v2
2005-04-11,Lorentz-violation and cosmological perturbations: a toy brane-world model,"We study possible effects of Lorentz-violation on the generation of
cosmological perturbations at inflation by introducing a simple inflating
five-dimensional brane-world setup with violation of four-dimensional
Lorentz-invariance at an energy scale $k$. We consider massless scalar field,
meant to mimic perturbations of inflaton and/or gravitational field, in this
background. At three-momenta below $k$, there exists a zero mode localized on
the brane, whose behaviour coincides with that in four-dimensional theory. On
the contrary, at three-momenta above $k$, the localized mode is absent and
physics is entirely five-dimensional. As three-momenta get redshifted, more
modes get localized on the brane, the phenomenon analogous to ``mode
generation''. We find that for $k\gg H$, where $H$ is the inflationary Hubble
scale, the spectrum of perturbations coincides with that in four-dimensional
theory. For $k < H$ and time-dependent bulk parameters, the spectrum deviates,
possibly strongly, from the flat spectrum even for pure de Sitter inflation.",0504249v2
2005-07-07,On the nature of X-Ray Flashes,"We discuss the origin of X-Ray Flashes (XRFs), a recently discovered class of
Gamma-Ray Bursts (GRBs). Using a simplified model for internal shocks we check
if XRFs can be intrinsically soft due to some specific values of the parameters
describing the relativistic outflow emerging from the central engine. We
generate a large number of synthetic events and find that XRFs are obtained
when the contrast Gamma_max/Gamma_min of the Lorentz factor distribution is
small while the average Lorentz factor Gamma is large. A few XRFs may be GRBs
at large redshifts but we exclude this possibility for the bulk of the
population. If outflows with a small contrast are commonly produced, even a
large population of XRFs could be explained. If conversely the Lorentz factor
distribution within the wind is broad, one should then rely on extrinsic
causes, such as viewing angle effects or high redshift.",0507173v1
2005-10-05,On the origin of the circular polarization in radio pulsars,"Properties of circularly polarized waves are studied in the pulsar
magnetosphere plasma. It is shown that some observational characteristics of
the circular polarization observed in the pulsar radio emission can be
qualitatively explained in the framework of the model based on anomalous
Doppler resonance. Performed analysis provides that if the difference between
Lorentz factors of electrons and positrons is relatively high, one of the
circularly polarized waves becomes super-luminal and therefore can not be
generated by cyclotron instability. We suggest that this case corresponds to
the pulsars with the domination of one hand of circular polarization through
the whole averaged pulse profile at all observed frequencies. For intermediate
values of the difference between Lorentz factors both circularly polarized
waves are generated, but the waves of one handness are much more effectively
generated for high frequencies, whereas generation of another handness
dominates for low frequencies. This should correspond to the pulsars with
strong frequency dependence of the degree of circular polarization. The case of
relatively small difference between Lorentz factors corresponds to the pulsars
with sign reversal of the circular polarization in the centre of averaged pulse
profiles.",0510116v1
2005-11-01,Distribution of Gamma-ray Burst Ejecta Energy with Lorentz Factor,"The early X-ray afterglow for a significant number of gamma-ray bursts
detected by the Swift satellite is observed to have a phase of very slow flux
decline with time ($F_\nu \propto t^{-\alpha}$ with $0.2 \lesssim \alpha
\lesssim 0.8$) for $10^{2.5} s \lesssim t \lesssim 10^4$ s, while the
subsequent decline is the usual $1 \lesssim \alpha_3 \lesssim 1.5$ behavior,
that was seen in the pre-Swift era. We show that this behavior is a natural
consequence of a small spread in the Lorentz factor of the ejecta, by a factor
of $\sim 2-4$, where the slower ejecta gradually catch-up with the shocked
external medium, thus increasing the energy of forward shock and delaying its
deceleration. The end of the ``shallow'' flux decay stage marks the beginning
of the Blandford-McKee self similar external shock evolution. This suggests
that most of the energy in the relativistic outflow is in material with a
Lorentz factor of $\sim 30-50$.",0511049v1
2006-01-24,GRB 051221A and Tests of Lorentz Symmetry,"Various approaches to quantum gravity suggest the possibility of violation of
Lorentz symmetry at very high energies. In these cases we expect a modification
at low energies of the dispersion relation of photons that contains extra
powers of the momentum suppressed by a high energy scale. These terms break
boost invariance and can be tested even at relatively low energies. We use the
light curves of the very bright short Gamma-Ray Burst GRB 051221A and compare
the arrival times of photons at different energies with the expected time delay
due to a modified dispersion relation. As no time delay was observed, we set a
lower bound of 0.0066 E_{pl} \sim 0.66 10^{17} GeV on the scale of Lorentz
invariance violation.",0601556v1
2006-02-20,A powerful hydrodynamic booster for relativistic jets,"Velocities close to the speed of light are a robust observational property of
the jets observed in microquasars and AGNs, and are expected to be behind much
of the phenomenology of GRBs. Yet, the mechanism boosting relativistic jets to
such large Lorentz factors is still essentially unknown. Building on recent
general-relativistic, multidimensional simulations of progenitors of short
GRBs, we discuss a new effect in relativistic hydrodynamics which can act as an
efficient booster in jets. This effect is purely hydrodynamical and occurs when
large velocities tangential to a discontinuity are present in the flow,
yielding Lorentz factors $\Gamma \sim 10^2-10^3$ or larger in flows with
moderate initial Lorentz factors. Although without a Newtonian counterpart,
this effect can be explained easily through the most elementary hydrodynamical
flow: i.e., a relativistic Riemann problem.",0602437v1
2006-03-27,Bulk Motion of Ultrarelativistic Conical Blazar Jets,"Allowing for the conical shape of ultrarelativistic blazar jets with opening
angles of a few degrees on parsec-scales we show that their bulk Lorentz
factors and viewing angles can be much larger than the values usually inferred
by combining their flux variability and proper motion measurements. This is in
accord with our earlier finding that such ultrarelativistic (Lorentz factor,
Gamma > 30) conical jets can reconcile the relatively slow apparent motions of
VLBI knots in TeV blazars with the extremely fast flows implied by their rapid
gamma-ray variability. This jet geometry also implies that de-projected jet
opening angles will typically be significantly underestimated from VLBI
measurements. In addition, de-projected jet lengths will be considerably
overestimated if high Lorentz factors and significant opening angles are not
taken into account.",0603727v1
2006-04-21,Flux-transport dynamos with Lorentz force feedback on differential rotation and meridional flow: Saturation mechanism and torsional oscillations,"In this paper we discuss a dynamic flux-transport dynamo model that includes
the feedback of the induced magnetic field on differential rotation and
meridional flow. We consider two different approaches for the feedback:
meanfield Lorentz force and quenching of transport coefficients such as
turbulent viscosity and heat conductivity. We find that even strong feedback on
the meridional flow does not change the character of the flux-transport dynamo
significantly; however it leads to a significant reduction of differential
rotation. To a large degree independent from the dynamo parameters, the
saturation takes place when the toroidal field at the base of the convection
zone reaches between 1.2 an 1.5 T, the energy converted intomagnetic energy
corresponds to about 0.1 to 0.2% of the solar luminosity. The torsional
oscillations produced through Lorentz force feedback on differential rotation
show a dominant poleward propagating branch with the correct phase relation to
the magnetic cycle. We show that incorporating enhanced surface cooling of the
active region belt (as proposed by Spruit) leads to an equatorward propagating
branch in good agreement with observations.",0604446v2
1996-06-14,"Lyapunov Exponents from Kinetic Theory for a Dilute, Field-driven Lorentz Gas","Positive and negative Lyapunov exponents for a dilute, random,
two-dimensional Lorentz gas in an applied field, $\vec{E}$, in a steady state
at constant energy are computed to order $E^{2}$. The results are:
$\lambda_{\pm}=\lambda_{\pm}^{0}-a_{\pm}(qE/mv)^{2}t_{0}$ where
$\lambda_{\pm}^{0}$ are the exponents for the field-free Lorentz gas,
$a_{+}=11/48, a_{-}=7/48$, $t_{0}$ is the mean free time between collisions,
$q$ is the charge, $m$ the mass and $v$ is the speed of the particle. The
calculation is based on an extended Boltzmann equation in which a radius of
curvature, characterizing the separation of two nearby trajectories, is one of
the variables in the distribution function. The analytical results are in
excellent agreement with computer simulations. These simulations provide
additional evidence for logarithmic terms in the density expansion of the
diffusion coefficient.",9606006v1
1999-01-20,Chaos and Maps in Relativistic Dynamical Systems,"The basic work of Zaslavskii et al showed that the classical non-relativistic
electromagnetically kicked oscillator can be cast into the form of an iterative
map on the phase space; the resulting evolution contains a stochastic flow to
unbounded energy. Subsequent studies have formulated the problem in terms of a
relativistic charged particle in interaction with the electromagnetic field. We
review the structure of the covariant Lorentz force used to study this problem.
We show that the Lorentz force equation can be derived as well from the
manifestly covariant mechanics of Stueckelberg in the presence of a standard
Maxwell field, establishing a connection between these equations and mass shell
constraints. We argue that these relativistic generalizations of the problem
are intrinsically inaccurate due to an inconsistency in the structure of the
relativistic Lorentz force, and show that a reformulation of the relativistic
problem, permitting variations (classically) in both the particle mass and the
effective ``mass'' of the interacting electromagnetic field, provides a
consistent system of classical equations for describing such processes.",9901016v1
1999-08-06,Thermostating by deterministic scattering: the periodic Lorentz gas,"We present a novel mechanism for thermalizing a system of particles in
equilibrium and nonequilibrium situations, based on specifically modeling
energy transfer at the boundaries via a microscopic collision process. We apply
our method to the periodic Lorentz gas, where a point particle moves
diffusively through an ensemble of hard disks arranged on a triangular lattice.
First, collision rules are defined for this system in thermal equilibrium. They
determine the velocity of the moving particle such that the system is
deterministic, time reversible, and microcanonical. These collision rules can
systematically be adapted to the case where one associates arbitrarily many
degrees of freedom to the disk, which here acts as a boundary. Subsequently,
the system is investigated in nonequilibrium situations by applying an external
field. We show that in the limit where the disk is endowed by infinitely many
degrees of freedom it acts as a thermal reservoir yielding a well-defined
nonequilibrium steady state. The characteristic properties of this state, as
obtained from computer simulations, are finally compared to the ones of the
so-called Gaussian thermostated driven Lorentz gas.",9908013v1
1999-09-23,"Kinetic Theory Estimates for the Kolmogorov-Sinai Entropy and the Largest Lyapunov Exponents for Dilute, Hard-Ball Gases and for Dilute, Random Lorentz Gases","The kinetic theory of gases provides methods for calculating Lyapunov
exponents and other quantities, such as Kolmogorov-Sinai entropies, that
characterize the chaotic behavior of hard-ball gases. Here we illustrate the
use of these methods for calculating the Kolmogorov-Sinai entropy, and the
largest positive Lyapunov exponent, for dilute hard-ball gases in equilibrium.
The calculation of the largest Lyapunov exponent makes interesting connections
with the theory of propagation of hydrodynamic fronts. Calculations are also
presented for the Lyapunov spectrum of dilute, random Lorentz gases in two and
three dimensions, which are considerably simpler than the corresponding
calculations for hard-ball gases. The article concludes with a brief discussion
of some interesting open problems.",9909034v2
1999-10-05,The existence of Burnett coefficients in the periodic Lorentz gas,"The linear super-Burnett coefficient gives corrections to the diffusion
equation in the form of higher derivatives of the density. Like the diffusion
coefficient, it can be expressed in terms of integrals of correlation
functions, but involving four different times. The power law decay of
correlations in real gases (with many moving particles) and the random Lorentz
gas (with one moving particle and fixed scatterers) are expected to cause the
super-Burnett coefficient to diverge in most cases. Here we show that the
expression for the super-Burnett coefficient of the periodic Lorentz gas
converges as a result of exponential decay of correlations and a nontrivial
cancellation of divergent contributions.",9910008v1
2006-10-12,Interaction corrections: temperature and parallel field dependencies of the Lorentz number in two-dimensional disordered metals,"The electron-electron interaction corrections to the transport coefficients
are calculated for a two-dimensional disordered metal in a parallel magnetic
field via the quantum kinetic equation approach. For the thermal transport,
three regimes (diffusive, quasiballistic and truly ballistic) can be identified
as the temperature increases. For the diffusive and quasiballistic regimes, the
Lorentz number dependence on the temperature and on the magnetic field is
studied. The electron-electron interactions induce deviations from the
Wiedemann-Franz law, whose sign depend on the temperature: at low temperatures
the long-range part of the Coulomb interaction gives a positive correction,
while at higher temperature the inelastic collisions dominate the negative
correction. By applying a parallel field, the Lorentz number becomes a
non-monotonic function of field and temperature for all values of the
Fermi-liquid interaction parameter in the diffusive regime, while in the
quasiballistic case this is true only sufficiently far from the Stoner
instability.",0610344v2
1995-08-28,Cosmological Implications of a Possible Class of Particles Able to Travel Faster than Light (abridged version),"Superluminal particles are not excluded by particle physics. The apparent
Lorentz invariance of the laws of physics does not imply that space-time is
indeed minkowskian. Matter made of solutions of Lorentz-invariant equations
would feel a relativistic space-time even if the actual space-time had a quite
different geometry (f.i. a galilean space-time). If Lorentz invariance is only
a property of equations describing a sector of matter at a given scale, an
absolute frame (the ""vacuum rest frame"") may exist without contradicting the
minkowskian structure felt by ordinary particles. Then c , the speed of light,
will not necessarily be the only critical speed in vacuum and superluminal
sectors of matter may equally exist feeling space-times with critical speeds
larger than c . We present a discussion of possible cosmological implications
of such a scenario, assuming that the superluminal sectors couple weakly to
ordinary matter. The universality of the equivalence between inertial and
gravitational mass will be lost. The Big Bang scenario will undergo important
modifications, and the evolution of the Universe may be strongly influenced by
superluminal particles.",9508054v1
1995-11-29,Consequences of the noncompactness of the Lorentz group,"The following four statements have been proven decades ago already, but they
continue to induce a strange feeling:
  - All curvature invariants of a gravitational wave vanish - in spite of the
fact that it represents a nonflat spacetime.
  - The eigennullframe components of the curvature tensor (the Cartan
''scalars'') do not represent curvature scalars.
  - The Euclidean topology in the Minkowski spacetime does not possess a basis
composed of Lorentz--invariant neighbourhoods.
  - There are points in the de Sitter spacetime which cannot be joined to each
other by any geodesic.
  We explain that our feeling is influenced by the compactness of the rotation
group; the strangeness disappears if we fully acknowledge the noncompactness of
the Lorentz group. Output: Imaginary coordinate rotations from Euclidean to
Lorentzian signature are very dangerous.",9512007v1
1999-04-09,A Lorentzian Signature Model for Quantum General Relativity,"We give a relativistic spin network model for quantum gravity based on the
Lorentz group and its q-deformation, the Quantum Lorentz Algebra.
  We propose a combinatorial model for the path integral given by an integral
over suitable representations of this algebra. This generalises the state sum
models for the case of the four-dimensional rotation group previously studied
in gr-qc/9709028.
  As a technical tool, formulae for the evaluation of relativistic spin
networks for the Lorentz group are developed, with some simple examples which
show that the evaluation is finite in interesting cases. We conjecture that the
`10J' symbol needed in our model has a finite value.",9904025v3
2000-05-23,"Is Nothing Sacred? Vacuum Energy, Supersymmetry and Lorentz Breaking from Recoiling D branes","Classical superstring vacua have zero vacuum energy and are supersymmetric
and Lorentz-invariant. We argue that all these properties may be destroyed when
quantum aspects of the interactions between particles and non-perturbative
vacuum fluctuations are considered. A toy calculation of string/D-brane
interactions using a world-sheet approach indicates that quantum recoil effects
- reflecting the gravitational back-reaction on space-time foam due to the
propagation of energetic particles - induce non-zero vacuum energy that is
linked to supersymmetry breaking and breaks Lorentz invariance. This model of
space-time foam also suggests the appearance of microscopic event horizons.",0005100v2
2000-07-17,Covariant and locally Lorentz-invariant varying speed of light theories,"We propose definitions for covariance and local Lorentz invariance applicable
when the speed of light $c$ is allowed to vary. They have the merit of
retaining only those aspects of the usual definitions which are invariant under
unit transformations, and which can therefore legitimately represent the
outcome of an experiment. We then discuss some possibilities for invariant
actions governing the dynamics of such theories. We consider first the
classical action for matter fields and the effects of a changing $c$ upon
quantization. We discover a peculiar form of quantum particle creation due to a
varying $c$. We then study actions governing the dynamics of gravitation and
the speed of light. We find the free, empty-space, no-gravity solution, to be
interpreted as the counterpart of Minkowksi space-time, and highlight its
similarities with Fock-Lorentz space-time. We also find flat-space string-type
solutions, in which near the string core $c$ is much higher. We label them
fast-tracks and compare them with gravitational wormholes. We finally discuss
general features of cosmological and black hole solutions, and digress on the
meaning of singularities in these theories.",0007036v1
2000-10-01,Gravitational Energy-Momentum in the Tetrad and Quadratic Spinor Representations of General Relativity,"In the Tetrad Representation of General Relativity, the energy-momentum
expression, found by Moller in 1961, is a tensor wrt coordinate transformations
but is not a tensor wrt local Lorentz frame rotations. This local Lorentz
freedom is shown to be the same as the six parameter normalized spinor degrees
of freedom in the Quadratic Spinor Representation of General Relativity. From
the viewpoint of a gravitational field theory in flat space-time, these extra
spinor degrees of freedom allow us to obtain a local energy-momentum density
which is a true tensor over both coordinate and local Lorentz frame rotations.",0010001v1
2001-04-12,The origins of length contraction: I. The FitzGerald-Lorentz deformation hypothesis,"One of the widespread confusions concerning the history of the 1887
Michelson-Morley experiment has to do with the initial explanation of this
celebrated null result due independently to FitzGerald and Lorentz. In neither
case was a strict, longitudinal length contraction hypothesis invoked, as is
commonly supposed. Lorentz postulated, particularly in 1895, any one of a
certain family of possible deformation effects for rigid bodies in motion,
including purely transverse alteration, and expansion as well as contraction;
FitzGerald may well have had the same family in mind. A careful analysis of the
Michelson-Morley experiment (which reveals a number of serious inadequacies in
many text-book treatments) indeed shows that strict contraction is not
required.",0104032v1
2001-05-30,The Cosmological Constant Problem in Brane--Worlds and Gravitational Lorentz Violations,"Brane worlds are theories with extra spatial dimensions in which ordinary
matter is localized on a (3+1) dimensional submanifold. Such theories could
have interesting consequences for particle physics and gravitational physics.
In this essay we concentrate on the cosmological constant (CC) problem in the
context of brane worlds. We show how extra-dimensional scenarios may violate
Lorentz invariance in the gravity sector of the effective 4D theory, while
particle physics remains unaffected. In such theories the usual no-go theorems
for adjustment of the CC do not apply, and we indicate a possible explanation
of the smallness of the CC. Lorentz violating effects would manifest themselves
in gravitational waves travelling with a speed different from light, which can
be searched for in gravitational wave experiments.",0105114v1
2002-01-17,Gravitation and the Local Symmetry Group of Spacetime,"According to general relativity, the interaction of a matter field with
gravitation requires the simultaneous introduction of a tetrad field, which is
a field related to translations, and a spin connection, which is a field
assuming values in the Lie algebra of the Lorentz group. These two fields,
however, are not independent. By analyzing the constraint between them, it is
concluded that the relevant local symmetry group behind general relativity is
provided by the Lorentz group. Furthermore, it is shown that the minimal
coupling prescription obtained from the Lorentz covariant derivative coincides
exactly with the usual coupling prescription of general relativity. Instead of
the tetrad, therefore, the spin connection is to be considered as the
fundamental field representing gravitation.",0201059v2
2002-05-25,Reconcile Planck-scale discreteness and the Lorentz-Fitzgerald contraction,"A Planck-scale minimal observable length appears in many approaches to
quantum gravity. It is sometimes argued that this minimal length might conflict
with Lorentz invariance, because a boosted observer could see the minimal
length further Lorentz contracted. We show that this is not the case within
loop quantum gravity. In loop quantum gravity the minimal length (more
precisely, minimal area) does not appear as a fixed property of geometry, but
rather as the minimal (nonzero) eigenvalue of a quantum observable. The boosted
observer can see the same observable spectrum, with the same minimal area. What
changes continuously in the boost transformation is not the value of the
minimal length: it is the probability distribution of seeing one or the other
of the discrete eigenvalues of the area. We discuss several difficulties
associated with boosts and area measurement in quantum gravity. We compute the
transformation of the area operator under a local boost, propose an explicit
expression for the generator of local boosts and give the conditions under
which its action is unitary.",0205108v1
2002-07-22,Generalized Lorentz invariance with an invariant energy scale,"The hypothesis that the Lorentz transformations may be modified at Planck
scale energies is further explored. We present a general formalism for theories
which preserve the relativity of inertial frames with a non-linear action of
the Lorentz transformations on momentum space. Several examples are discussed
in which the speed of light varies with energy and elementary particles have a
maximum momenta and/or energy. Energy and momentum conservation are suitably
generalized and a proposal is made for how the new transformation laws apply to
composite systems. We then use these results to explain the ultra high energy
cosmic ray anomaly and we find a form of the theory that explains the anomaly,
and leads also to a maximum momentum and a speed of light that diverges with
energy. We finally propose that the spatial coordinates be identified as the
generators of translation in Minkowski spacetime. In some examples this leads
to a commutative geometry, but with an energy dependent Planck constant.",0207085v1
2003-11-20,Propagation in a thermal graviton background,"It is well known that radiative corrections evaluated in nontrivial
backgrounds lead to effective dispersion relations which are not Lorentz
invariant. Since gravitational interactions increase with energy,
gravity-induced radiative corrections could be relevant for the trans-Planckian
problem. As a first step to explore this possibility, we compute the one-loop
radiative corrections to the self-energy of a scalar particle propagating in a
thermal bath of gravitons in Minkowski spacetime. We obtain terms which
originate from the thermal bath and which indeed break the Lorentz invariance
that possessed the propagator in the vacuum. Rather unexpectedly, however, the
terms which break Lorentz invariance vanish in the high three-momentum limit.
We also found that the imaginary part, which gives the rate of approach to
thermal equilibrium, vanishes at one loop.",0311065v3
2004-02-11,The moduli space of isometry classes of globally hyperbolic spacetimes,"This is the last article in a series of three initiated by the second author.
We elaborate on the concepts and theorems constructed in the previous articles.
In particular, we prove that the GH and the GGH uniformities previously
introduced on the moduli space of isometry classes of globally hyperbolic
spacetimes are different, but the Cauchy sequences which give rise to
well-defined limit spaces coincide. We then examine properties of the strong
metric introduced earlier on each spacetime, and answer some questions
concerning causality of limit spaces. Progress is made towards a general
definition of causality, and it is proven that the GGH limit of a Cauchy
sequence of $\mathcal{C}^{\pm}_{\alpha}$, path metric Lorentz spaces is again a
$\mathcal{C}^{\pm}_{\alpha}$, path metric Lorentz space. Finally, we give a
necessary and sufficient condition, similar to the one of Gromov for the
Riemannian case, for a class of Lorentz spaces to be precompact.",0402049v1
2005-12-15,Locally Lorentz-Covariant Theory of Gravity Founded on Inertial Frame of Center of Mass,"A Locally Lorentz-covariant theory of gravity which is equivalent to general
relativity in weak gravitational field is present. The space-time standard in
local gravitational field is modified in terms of equivalence principle to keep
consistent with that of inertial frame. The static metric in our theory agrees
with Schwarzschild metric at first order approximation. The gravitational
vector potential produced by a moving body is obtained by applying local
Lorentz transformations in gravitational field. On the other hand, we still
regard inertial frame, i.e. center of mass of the system, as the preferred
frame of reference. This is because Newton's laws of motion hold only for
inertial frames. The apsidal motion of binary system and the expansion of the
universe can be explained reasonably when observed from inertial frame. Black
holes and singularities do not exist in our theory.",0512088v6
2005-12-30,Supersymmetric Lorentz invariant deformations of superspaces,"Lorentz invariant supersymmetric deformations of superspaces based on Moyal
star product parametrized by Majorana spinor $\lambda_{a}$ and Ramond
grassmannian vector $\psi_{m}=-{1\over 2}(\bar\theta\gamma_{m}\lambda)$ in the
spinor realization \cite{VZ} are proposed. The map of supergravity background
into composite supercoordinates: $(B^{-1}_{mn}, \Psi^{a}_{m}, C_{ab})
\leftrightarrow (i\psi_{m}\psi_{n}, \psi_{m}\lambda^{a},
\lambda_{a}\lambda_{b})$ valid up to the second order corrections in
deformation parameter $h$ and transforming the background dependent Lorentz
noninvariant (anti)commutators of supercoordinates into their invariant Moyal
brackets is revealed. We found one of the deformations to depend on the axial
vector $\psi_{1m}={1/2}(\bar\theta\gamma_{m}\gamma_{5}\lambda)$ and to vanish
for the $\theta$ components with the same chiralities. The deformations in the
(super)twistor picture are discussed.",0512166v1
2006-04-25,A Lorentz-Poincaré type interpretation of the Weak Equivalence Principle,"The validity of the Weak Equivalence Principle relative to a local inertial
frame is detailed in a scalar-vector gravitation model with Lorentz-Poincar\'e
type interpretation. Given the previously established first Post-Newtonian
concordance of dynamics with General Relativity, the principle is to this order
compatible with GRT. The gravitationally modified Lorentz transformations, on
which the observations in physical coordinates depend, are shown to provide a
physical interpretation of \emph{parallel transport}. A development of
``geodesic'' deviation in terms of the present model is given as well.",0604107v3
2006-10-13,White dwarfs as test objects of Lorentz violations,"In the present work the thermodynamical properties of bosonic and fermionic
gases are analyzed under the condition that a modified dispersion relation is
present. This last condition implies a breakdown of Lorentz symmetry. The
implications upon the condensation temperature will be studied, as well, as
upon other thermodynamical variables such as specific heat, entropy, etc.
Moreover, it will be argued that those cases entailing a violation of time
reversal symmetry of the motion equations could lead to problems with the
concept of entropy. Concerning the fermionic case it will be shown that Fermi
temperature suffers a modification due to the breakdown of Lorentz symmetry.
The results will be applied to white dwarfs and the consequences upon the
Chandrasekhar mass--radius relation will be shown. The possibility of resorting
to white dwarfs for the testing of modified dispersion relations is also
addressed. It will be shown that the comparison of the current observations
against the predictions of our model allows us to discard some values of one of
the parameters appearing in the modifications of the dispersion relation.",0610073v1
2006-11-13,"Then again, how often does the Unruh-DeWitt detector click if we switch it carefully?","The transition probability in first-order perturbation theory for an
Unruh-DeWitt detector coupled to a massless scalar field in Minkowski space is
calculated. It has been shown recently that the conventional $i\epsilon$
regularisation prescription for the correlation function leads to non-Lorentz
invariant results for the transition rate, and a different regularisation,
involving spatial smearing of the field, has been advocated to replace it. We
show that the non-Lorentz invariance arises solely from the assumption of
sudden switch-on and switch-off of the detector, and that when the model
includes a smooth switching function the results from the conventional
regularisation are both finite and Lorentz invariant. The sharp switching limit
of the model is also discussed, as well as the falloff properties of the
spectrum for large frequencies.",0611067v3
2000-12-01,Lorentz Angle Measurement for CO2/Isobutane Gas Mixtures,"We have developed a Lorentz angle measurement system for cool gas mixtures in
the course of our R&D for a proposed JLC central drift chamber (JLC-CDC). The
measurement system is characterized by the use of two laser beams to produce
primary electrons and flash ADCs to read their signals simultaneously. With
this new system, we have measured Lorentz angles for CO2/isobutane gas mixtures
with different proportions (95:5, 90:10, and 85:15), varying drift field from
0.6 to 2.0 kV/cm and magnetic field up to 1.5 T. The results of the measurement
are in good agreement with GARFIELD/MAGBOLTZ simulations.",0012002v1
1999-04-01,Lorentz gauge and Gribov ambiguity in the compact lattice U(1) theory,"The Gribov ambiguity problem is studied for compact U(1) lattice theory
within the Lorentz gauge. In the Coulomb phase, it is shown that apart from
double Dirac sheets all gauge (i.e. Gribov) copies originate mainly from the
zero-momentum modes of the gauge fields. The removal of the zero-momentum modes
turns out to be necessary for reaching the absolute maximum of the gauge
functional $F(\theta)$. A new gauge fixing procedure - zero-momentum Lorentz
gauge - is proposed.",9904001v1
1992-07-27,"Color Confinement, Abelian Gauge and Renormalization Group Flow","Under the assumption that the color charge can be written in a BRST exact
form, the color confinement mechanism proposed by Kugo and Ojima (KO) explains
the confinement of any colored particles including dynamical quarks and gluons.
This mechanism, however, is known to break down in the Abelian gauge which
treats the maximal Abelian subgroup of the gauge group in a special manner. In
order to study whether the failure of the KO mechanism is particular only to
the Abelian gauge or whether this failure occurs in a wide class of gauges
including the ordinary Lorentz type gauge, we carry out a renormalization group
study of the $SU(2)$ gauge theory in the gauge fixing space. Our gauge fixing
space consists of four distinct regions that are not connected with each other
by renormalization group flows, and we find that the Abelian gauge is {\it
infrared unstable} in three regions which include the Lorentz type gauge. This
suggests that the failure of the KO mechanism is a phenomenon which occurs only
in the Abelian gauge. We also find that the Lorentz gauge is infrared stable.",9207260v1
1997-07-15,Nucleon Structure Functions from a Chiral Soliton in the Infinite Momentum Frame,"We study the frame dependence of nucleon structure functions obtained within
a chiral soliton model for the nucleon. Employing light cone coordinates and
introducing collective coordinates together with their conjugate momenta,
translational invariance of the solitonic quark fields (which describe the
nucleon as a localized object) is restored. This formulation allows us to
perform a Lorentz boost to the infinite momentum frame of the nucleon. The
major result is that the Lorentz contraction associated with this boost causes
the leading twist contribution to the structure functions to properly vanish
when the Bjorken variable $x$ exceeds unity. Furthermore we demonstrate that
for structure functions calculated in the valence quark approximation to the
Nambu--Jona--Lasinio chiral soliton model the Lorentz contraction also has
significant effects on the structure functions for moderate values of the
Bjorken variable $x$.",9707352v2
1997-09-15,Test of Special Relativity from K Physics,"A breakdown of the Local Lorentz Invariance and hence the special theory of
relativity in the Kaon system can, in principle, induce oscillations between
the $K^0$ and $\bar{K}^0$ states. We construct a general formulation in which
simultaneous pairwise diagonalization of mass, momentum and weak eigenstates is
not assumed and the maximum attainable speeds of the momentum eigenstates are
different. This mechanism permits Local Lorentz Invariance violation in a
manner that may or may not violate CPT. In the $CPT-$conserving case, we show
that violation of special relativity could be clearly tested experimentally via
the energy dependence of the $K_L-K_S$ mass difference and we discuss
constraints imposed by present experiments. In the CPT-violating case the
$K^0$--$\bar{K}^0$ system also allows the possiblity of testing different
Lorentz properties of matter and antimatter.",9709350v2
1998-04-29,Patterns of Lorentz symmetry breaking in QED by CPT-odd interaction,"A tiny Lorentz symmetry breaking can be mediated in Electrodynamics by means
of the Chern-Simons (CS) interaction polarized along a constant CS vector. Its
presence makes the vacuum optically active that has been recently estimated
from astrophysical data. We examine two possibilities for the CS vector to be
time-like or space-like, under the assumption that it originates from v.e.v. of
some pseudoscalar matter. It is shown that: a) a time-like CS vector makes the
vacuum unstable under pairs creation of tachyonic photon modes with the finite
vacuum decay rate, i.e. it is unlikely realized at macroscopic time scales; b)
on the contrary, the space-like CS vector does not yield any tachyonic modes
and, moreover, if its dynamical counterpart is substantially described by a
scale invariant interaction, then the QED radiation effects induce the
dynamical breaking of Lorentz symmetry, i.e. the occurrence of space-like CS
vector appears to be rather natural.",9804448v3
1998-11-04,A Bound on Violations of Lorentz Invariance,"Recently Coleman and Glashow [1] have developed a model which allows the
introduction of a small violation of Lorentz invariance. Observational
signatures arise because this interaction also violates flavor conservation and
allows the radiative decay of the muon, $\mu \to e + \gamma$, whose branching
ratio increases as b $\gamma^4$ where $\gamma$ is the Lorentz factor of the
muon with respect to the reference frame in which the dipole anisotropy of the
universal microwave radiation vanishes. In this paper we place a bound of b$<
10^{-25}$ based on observations of horizontal air showers with $n_e \geq 5
\times 10^6$. With such small values of b the proposed radiative decay of the
muon will not affect the functioning of the muon collider.(THIS IS A
PRELIMINARY VERSION)",9811241v2
1998-12-17,High-Energy Tests of Lorentz Invariance,"We develop a perturbative framework with which to discuss departures from
exact Lorentz invariance and explore their potentially observable
ramifications. Tiny non-invariant terms introduced into the standard model
Lagrangian are assumed to be renormalizable (dimension $\le 4$), invariant
under $SU(3)\otimes SU(2)\otimes U(1)$ gauge transformations, and rotationally
and translationally invariant in a preferred frame. There are a total of 46
independent TCP-even perturbations of this kind, all of which preserve anomaly
cancellation. They define the energy-momentum eigenstates and their maximal
attainable velocities in the high-energy limit. The effects of these
perturbations increase rapidly with energy in the preferred frame, more rapidly
than those of TCP-odd perturbations. Our analysis of Lorentz-violating
kinematics reveals several striking new phenomena that are relevant both to
cosmic-ray physics ({\it e.g.,} by undoing the GZK cutoff) and neutrino physics
({\it e.g.,} by generating novel types of neutrino oscillations). These may
lead to new and sensitive high-energy tests of special relativity.",9812418v3
1999-01-11,Extending the Standard Model to Include CPT- and Lorentz-Breaking Terms,"Low-energy remnant fundamental symmetry violations may be present in nature
at levels attainable in upcoming experiments. These effects may arise through
spontaneous symmetry breaking in a more complete Lorentz covariant theory
underlying the standard model. In this work the issue of parameterizing such
violations in a consistent and complete manner is addressed. The approach is to
use the mechanism of spontaneous symmetry breaking to generate all possible
terms consistent with gauge invariance and power-counting renormalizability to
construct an extension of the standard model that includes Lorentz- and
CPT-breaking terms. A consistent quantization of the theory is developed,
conventional quantum field theoretic techniques are shown to apply, and some
ramifications for quantum electrodynamics are explored.",9901269v1
2001-10-27,Has spacetime torsion already been detected in Lorentz and CPT tests with spin-polarised bodies?,"Bluhm-Kostelecky (BK) Lagrangian to test Lorentz violation with
spin-polarised test bodies is shown to be transformed to a torsion-coupling
constant Lagrangian by taking into account the Fock-Ivanenko coefficients in
spinor form. In this way one is able to introduce torsion in their Lagrangian
and make use of the value of their coupling constant to infer that torsion
maybe observed in this type of spin-polarised body experiment.The theory would
be a low-energy limit of a quasi-Riemannian gravity in Riemann-Cartan spacetime
previously proposed by Gasperini.In this theory of gravity Lorentz local gauge
symmetry is violated while global coordinate transformations are
preserved.Torsion coupling obtained in this way could be as high as $10^{-29}
GeV$.",0110361v1
2003-06-29,Lorentz invariance violation in top-down scenarios of ultrahigh energy cosmic ray creation,"The violation of Lorentz invariance (LI) has been invoked in a number of ways
to explain issues dealing with ultrahigh energy cosmic ray (UHECR) production
and propagation. These treatments, however, have mostly been limited to
examples in the proton-neutron system and photon-electron system. In this paper
we show how a broader violation of Lorentz invariance would allow for a series
of previously forbidden decays to occur, and how that could lead to UHECR
primaries being heavy baryonic states or Higgs bosons.",0306288v2
2003-07-02,Implications of Spacetime Quantization for the Bahcall-Waxman Neutrino Bound,"There is growing interest in quantum-spacetime models in which small
departures from Lorentz symmetry are governed by the Planck scale. In
particular, several studies have considered the possibility that these small
violations of Lorentz symmetry may affect various astrophysical observations,
such as the evaluation of the GZK limit for cosmic rays, the interaction of TeV
photons with the Far Infrared Background and the arrival time of photons with
different energies from cosmological sources. We show that the same
Planck-scale departures from Lorentz symmetry that lead to a modification of
the GZK limit which would be consistent with the observations reported by
AGASA, also have significant implications for the evaluation of the
Bahcall-Waxman bound on the flux of high-energy neutrinos produced by
photo-meson interactions in sources of size not much larger than the proton
photo-meson mean free path.",0307027v1
2003-08-25,The Pion Velocity at Chiral Restoration and the Vector Manifestation,"We study the effects of Lorentz non-invariance on the physical pion velocity
at the critical temperature $T_c$ in an effective theory of hidden local
symmetry (HLS) with the ""vector manifestation"" fixed point. We match at a
""matching scale"" $\Lambda_M$ the axial-vector current correlator in the HLS
with the one in the operator product expansion for QCD, and present the
matching condition to determine the bare pion velocity. We find that the
physical pion velocity, which is found to be one at $T=T_c$ when starting from
the Lorentz invariant bare HLS, remains close to one with the Lorentz
non-invariance, $v_\pi (T_c) = 0.83 - 0.99$. This result is quite similar to
the pion velocity in dense matter.",0308237v2
2004-03-10,Lorentz and CPT Violation in the Higgs Sector,"Colladay and Kostelecky have proposed a framework for studying Lorentz and
CPT violation in a natural extension of the Standard Model. Although numerous
bounds exist on the Lorentz and CPT violating parameters in the gauge boson and
fermion sectors, there are no published bounds on the parameters in the Higgs
sector. We determine these bounds. The bounds on the CPT-even asymmetric
coefficients arise from the one-loop contributions to the photon propagator,
those from the CPT-even symmetric coefficients arise from the equivalent
c_{\mu\nu} coefficients in the fermion sector, and those from the CPT-odd
coefficient arise from bounds on the vacuum expectation value of the Z-boson.",0403116v2
2004-07-07,Atmospheric Neutrino Constraints on Lorentz Violation,"Sensitive tests of Lorentz invariance can emerge from the study of neutrino
oscillations, particularly for atmospheric neutrinos where the effect is
conveniently near-maximal and has been observed over a wide range of energies.
We assume these oscillations to be described in terms of two neutrinos with
different masses and (possibly) different maximal attainable velocities (MAVs).
It suffices to examine limiting cases in which neutrino velocity eigenstates
coincide with either their mass or flavor eigenstates. We display the modified
mu to tau neutrino transition probability for each case. Data on atmospheric
neutrino oscillations at the highest observed energies and pathlengths can
yield constraints on neutrino MAV differences (i.e., tests of special
relativity) more restrictive than any that have been obtained to date on
analogous Lorentz-violating parameters in other sectors of particle physics.",0407087v1
2004-09-03,The Bounds on Lorentz and CPT Violating Parameters in the Higgs Sector,"In this talk, I discuss possible bounds on the Lorentz and CPT violating
parameters in the Higgs sector of the so called minimal standard model
extension. The main motivation to this study is coming from the fact that
unlike the parameters in the fermion and gauge sector, there are no published
bounds on the parameters in the Higgs sector. From the one-loop contributions
to the photon propagator the bounds on the CPT-even asymmetric coefficients are
obtained and the c_\mu\nu coefficients in the fermion sector determine the
bound on the CPT-even symmetric coefficients. The CPT-odd coefficient is
bounded from the non-zero vacuum expectation value of the Z-boson.",0409044v1
2004-09-28,Electrophobic Lorentz invariance violation for neutrinos and the see-saw mechanism,"In this talk we show how Lorentz invariance violation (LIV) can occur for
Majorana neutrinos, without inducing LIV in the charged leptons via radiative
corrections. Such ``electrophobic'' LIV is due to the Majorana nature of the
LIV operator together with electric charge conservation. Being free from the
strong constraints coming from the charged lepton sector, electrophobic LIV can
in principle be as large as current neutrino experiments permit. On the other
hand electrophobic LIV could be naturally small if it originates from LIV in
some singlet ``right-handed neutrino'' sector, and is felt in the physical
left-handed neutrinos via a see-saw mechanism.",0409323v1
2004-12-20,Bounds on Cubic Lorentz-Violating Terms in the Fermionic Dispersion Relation,"We study the recently proposed Lorentz-violating dispersion relation for
fermions and show that it leads to two distinct cubic operators in the
momentum. We compute the leading order terms that modify the non-relativistic
equations of motion and use experimental results for the hyperfine transition
in the ground state of the ${}^9\textrm Be^+$ ion to bound the values of the
Lorentz-violating parameters $\eta_1$ and $\eta_2$ for neutrons. The resulting
bounds depend on the value of the Lorenz-violating background four-vector in
the laboratory frame.",0412289v2
2005-03-01,Effects of CPT and Lorentz Invariance Violation on Pulsar Kicks,"The breakdown of Lorentz's and CPT invariance, as described by the Extension
of the Standard Model, gives rise to a modification of the dispersion relation
of particles. Consequences of such a modification are reviewed in the framework
of pulsar kicks induced by neutrino oscillations (active-sterile conversion). A
peculiar feature of the modified energy-momentum relations is the occurrence of
terms of the form $\delta {\bbox \Pi}\cdot {\bf {\hat p}}$, where $\delta
{\bbox \Pi}$ accounts for the difference of spatial components of flavor
depending coefficients which lead to the departure of the Lorentz symmetry, and
${\bf {\hat p}}={\bf p}/p$, being ${\bf p}$ the neutrino momentum. Owing to the
relative orientation of ${\bf p}$ with respect to $\delta {\bbox \Pi}$, the
{\it coupling} $\delta {\bbox \Pi}\cdot {\bf {\hat p}}$ may induce the
mechanism to generate the observed pulsar velocities. Topics related to the
velocity distribution of pulsars are also discussed.",0503002v1
2005-09-14,Lorentz-violating brane worlds and cosmological perturbations,"We consider an inflating brane-world setup in which 4-dimensional
Lorentz-invariance is violated at high 3-momentum scale $P_{LV} \gg H$, where
$H$ is the inflationary Hubble parameter. We study massless scalar field in
this background as a model for cosmological perturbations. Towards the end of
inflation, the spectrum has both the standard, 4-dimensional part due to a
brane-localized mode, and exotic, bulk induced contribution. The suppression of
the latter is power-law only, $(H/P_{LV})^\alpha$, provided that there exist
bulk modes with energies $\omega \ll H$. Contrary to general expectations, the
exponent $\alpha$ may be smaller than 2, and even smaller than 1, depending on
details of the bulk geometry. Furthermore, the overall amplitude of the
bulk-induced perturbations is enhanced as compared to the standard part, so the
effects due to Lorentz-violation may dominate over the standard mechanism even
for $P_{LV} \gg H$.",0509148v1
2005-10-07,Models of Baryogenesis via Spontaneous Lorentz Violation,"In the presence of background fields that spontaneously violate Lorentz
invariance, a matter-antimatter asymmetry can be generated even in thermal
equilibrium. In this paper we systematically investigate models of this type,
showing that either high-energy or electroweak versions of baryogenesis are
possible, depending on the dynamics of the Lorentz-violating fields. In
addition to the previously-studied models of spontaneous baryogenesis and
quintessential baryogenesis, we identify two scenarios of interest:
baryogenesis from a pseudo-Nambu-Goldstone boson with weak-scale mass and
intermediate-scale baryon-number violation, and sphaleron-induced baryogenesis
driven by a constant-magnitude vector with a late-time phase transition.",0510081v3
2005-10-27,On extrapolations below the Planck scale in models with Lorentz symmetry violation (I),"Most current models of Lorentz symmetry violation (LSV) at the Planck scale
involve power-like extrapolations of the Lorentz-beaking term down to
accelerator and even much lower energies. It is therefore assumed that no
intermediate energy scale alters this behaviour. But this is not the only
possible scenario: a more sophisticate energy-dependence is possible, and would
even be natural, involving significant effective thresholds at intermediate
energies. Such thresholds may exist between the Planck scale and the highest
cosmic-ray energies, or between ultra-high cosmic-ray energies and the TeV
scale, leading to interesting scenarios. In many cases, experimental
predictions of LSV patterns can be dramatically modified and space experiments
become necessary irrespective of AUGER results. By combining both kinds of
experiments, future results of cosmic-ray observations will hopefully be able
to test, for a large family of models involving various patterns of
Planck-scale physics, the possible existence of an absolute local rest frame in
the real world.",0510361v1
2006-01-04,Cold Atom Clock Test of Lorentz Invariance in the Matter Sector,"We report on a new experiment that tests for a violation of Lorentz
invariance (LI), by searching for a dependence of atomic transition frequencies
on the orientation of the spin of the involved states (Hughes-Drever type
experiment). The atomic frequencies are measured using a laser cooled
$^{133}$Cs atomic fountain clock, operating on a particular combination of
Zeeman substates. We analyze the results within the framework of the Lorentz
violating standard model extension (SME), where our experiment is sensitive to
a largely unexplored region of the SME parameter space, corresponding to first
measurements of four proton parameters and improvements by 11 and 13 orders of
magnitude on the determination of four others. In spite of the attained
uncertainties, and of having extended the search into a new region of the SME,
we still find no indication of LI violation.",0601024v1
2006-08-31,Synchrotron and Inverse Compton Constraints on Lorentz Violations for Electrons,"We present a method for constraining Lorentz violation in the electron
sector, based on observations of the photons emitted by high-energy
astrophysical sources. The most important Lorentz-violating operators at the
relevant energies are parameterized by a tensor c^{nu mu) with nine independent
components. If c is nonvanishing, then there may be either a maximum electron
velocity less than the speed of light or a maximum energy for subluminal
electrons; both these quantities will generally depend on the direction of an
electron's motion. From synchrotron radiation, we may infer a lower bound on
the maximum velocity, and from inverse Compton emission, a lower bound on the
maximum subluminal energy. With observational data for both these types of
emission from multiple celestial sources, we may then place bounds on all nine
of the coefficients that make up c. The most stringent bound, on a certain
combination of the coefficients, is at the 6 x 10^(-20) level, and bounds on
the coefficients individually range from the 7 x 10^(-15) level to the 2 x
10^(-17) level. For most of the coefficients, these are the most precise bounds
available, and with newly available data, we can already improve over previous
bounds obtained by the same methods.",0608332v1
2006-11-07,Parity doublers in chiral potential quark models,"The effect of spontaneous breaking of chiral symmetry over the spectrum of
highly excited hadrons is addressed in the framework of a microscopic chiral
potential quark model (Generalised Nambu-Jona-Lasinio model) with a vectorial
instantaneous quark kernel of a generic form. A heavy-light quark-antiquark
bound system is considered, as an example, and the Lorentz nature of the
effective light-quark potential is identified to be a pure Lorentz-scalar, for
low-lying states in the spectrum, and to become a pure spatial Lorentz vector,
for highly excited states. Consequently, the splitting between the partners in
chiral doublets is demonstrated to decrease fast in the upper part of the
spectrum so that neighboring states of an opposite parity become almost
degenerate. A detailed microscopic picture of such a ""chiral symmetry
restoration"" in the spectrum of highly excited hadrons is drawn and the
corresponding scale of restoration is estimated.",0611081v1
1992-07-31,Relativistic Rigid Particles: Classical Tachyons and Quantum Anomalies,"Causal rigid particles whose action includes an {\it arbitrary} dependence on
the world-line extrinsic curvature are considered. General classes of solutions
are constructed, including {\it causal tachyonic} ones. The Hamiltonian
formulation is developed in detail except for one degenerate situation for
which only partial results are given and requiring a separate analysis.
However, for otherwise generic rigid particles, the precise specification of
Hamiltonian gauge symmetries is obtained with in particular the identification
of the Teichm$\ddot{\rm u}$ller and modular spaces for these systems. Finally,
canonical quantisation of the generic case is performed paying special
attention to the phase space restriction due to causal propagation. A mixed
Lorentz-gravitational anomaly is found in the commutator of Lorentz boosts with
world-line reparametrisations. The subspace of gauge invariant physical states
is therefore not invariant under Lorentz transformations. Consequences for
rigid strings and membranes are also discussed.",9207110v1
1994-04-30,Supersymmetry algebras and Lorentz invariance for d=10 Super Yang-Mills,"We consider ways in which conventional supersymmetry can be embedded in the
set of more general fermionic transformations proposed recently [\Ref{B}] as a
framework in which to study $d=10$ super Yang-Mills. Solutions are exhibited
which involve closed algebras of various numbers of supersymmetries together
with their invariance groups: nine supersymmetries with $\GT {\times}\SO (1,1)$
invariance; eight supersymmetries with $\SO (7){\times}\SO (1,1)$ invariance;
four supersymmetries with $\SO (3,1){\times}\U (3)$ invariance. We recover in
this manner all previously known ways of adding finite numbers of bosonic
auxiliary fields so as to partially close the $d=10$ superalgebra. A crucial
feature of these solutions is that the auxiliary fields transform non-trivially
under the residual Lorentz symmetry, even though they are originally introduced
as Lorentz scalars.",9404190v1
1996-03-29,Lorentz Surfaces and Lorentzian CFT --- with an appendix on quantization of string phase space,"The interest in string Hamiltonian system has recently been rekindled due to
its application to target-space duality. In this article, we explore another
direction it motivates. In Sec.\ 1, conformal symmetry and some algebraic
structures of the system that are related to interacting strings are discussed.
These lead one naturally to the study of Lorentz surfaces in Sec.\ 2. In
contrast to the case of Riemann surfaces, we show in Sec.\ 3 that there are
Lorentz surfaces that cannot be conformally deformed into Mandelstam diagrams.
Lastly in Sec.\ 4, we discuss speculatively the prospect of Lorentzian
conformal field theory.
  Additionally, to have a view of what quantum picture a string Hamiltonian
system may lead to, we discuss independently in the Appendix a formal geometric
quantization of the string phase space.",9603198v1
1996-06-26,Invariant Regularization of Anomaly-Free Chiral Theories,"We present a generalization of the Frolov-Slavnov invariant regularization
scheme for chiral fermion theories in curved spacetimes. local gauge symmetries
of the theory, including local Lorentz invariance. The perturbative scheme
works for arbitrary representations which satisfy the chiral gauge anomaly and
the mixed Lorentz-gauge anomaly cancellation conditions. Anomalous theories on
the other hand manifest themselves by having divergent fermion loops which
remain unregularized by the scheme. Since the invariant scheme is promoted to
also include local Lorentz invariance, spectator fields which do not couple to
gravity cannot be, and are not, introduced. Furthermore, the scheme is truly
chiral (Weyl) in that all fields, including the regulators, are left-handed;
and only the left-handed spin connection is needed. The scheme is, therefore,
well suited for the study of the interaction of matter with all four known
forces in a completely chiral fashion. In contrast with the vectorlike
formulation, the degeneracy between the Adler-Bell-Jackiw current and the
fermion number current in the bare action is preserved by the chiral
regularization scheme.",9606174v2
1996-08-29,Restoring Reality for the Self-Dual N=2 String,"It is known that the critical N=(2,2) string describes 2+2 dimensional
self-dual gravity in a non-covariant form, since it requires the choice of a
complex structure in the target, which leaves only U(1,1) Lorentz symmetry. We
briefly review picture-changing and spectral flow and show that the world-sheet
Maxwell instantons individually break the Lorentz group further to SU(1,1).
However, their contributions conspire to restore full SO(2,2) global symmetry
if dilaton and axion fields are assembled in a null anti-self-dual two-form,
denying them the status of Lorentz scalars. We present the fully SO(2,2)
invariant tree-level three-point amplitude and the corresponding extension of
the Plebanski action for self-dual gravity.",9608196v1
1996-10-16,World-manifold and target space anomalies in heterotic Green-Schwarz strings and five-branes,"The quantum consistency of sigma-models describing the dynamics of extended
objects in a curved background requires the cancellation of their world-volume
anomalies, which are conformal anomalies for the heterotic string and $SO(1,5)$
Lorentz-anomalies for the heterotic five-brane, and of their ten dimensional
target space anomalies. In determining these anomalies in a $D=10$
Lorentz-covariant back-ground gauge we find that for the heterotic string the
worldvolume anomalies cancel for 32 heterotic fermions while for the
conjectured heterotic five-brane they cancel for only 16 heterotic fermions,
this result being in contrast with the string/five-brane duality conjecture.
For what concerns the target space anomalies we find that the five-brane
eight-form Lorentz-anomaly polynomial differs by a factor of $1/2$ from what is
expected on the basis of duality. Possible implications of these results are
discussed.",9610110v1
1996-11-09,Interacting Chiral Gauge Fields in Six Dimensions and Born-Infeld Theory,"Dimensional reduction of a self-dual tensor gauge field in 6d gives an
Abelian vector gauge field in 5d. We derive the conditions under which an
interacting 5d theory of an Abelian vector gauge field is the dimensional
reduction of a 6d Lorentz invariant interacting theory of a self-dual tensor.
Then we specialize to the particular 6d theory that gives 5d Born-Infeld
theory. The field equation and Lagrangian of this 6d theory are formulated with
manifest 5d Lorentz invariance, while the remaining Lorentz symmetries are
realized nontrivially. A string soliton with finite tension and self-dual
charge is constructed.",9611065v1
1997-02-06,Lorentz Group derivable from Polarization Optics,"The Lorentz group is the fundamental language for space-time symmetries of
relativistic particles. This group can these days be derived from the
symmetries observed in other branches of physics. It is shown that this group
can be derived from optical filters. The group O(2,1) is appropriate for
attenuation filters, while the O(3) group describes phase-shift filters. The
combined operation leads to a two-by-two representation of the six-parameter
Lorentz group. It is shown also that the bilinear representation of this group
is the natural language for the polarization optics.",9702055v1
1998-05-28,Massive Gauge Field Theory Without Higgs Mechanism I. .Quantization,"According to the conventional concept of the gauge field theory, the local
gauge invariance excludes the possibility of giving a mass to the gauge boson
without resorting to the Higgs mechanism because the Lagrangian constructed by
adding a mass term to the Yang-Mills Lagrangian is not only
gauge-non-invariant, but also unrenormalizable. On the contrary, we argue that
the principle of gauge invariance actually allows a mass term to enter the
Lagrangian if the Lorentz constraint condition is taken into account at the
same time. The Lorentz condition, which implies vanishing of the unphysical
longitudinal field, defines a gauge-invariant physical space for the massive
gauge field. The quantum massive gauge field theory without Higgs mechanism may
well be established by using a BRST-invariant action which is constructed by
the Lagrange undetermined multiplier procedure of incorporating the Lorentz
condition and another condition constraining the gauge group into the original
massive Yang-Mills action. The quantum theory established in this way shows
good renormalizability.",9805195v2
1998-06-17,"D=10, N=IIB Supergravity: Lorentz-invariant actions and duality","We present a manifestly Lorentz invariant and supersymmetric component field
action for $D = 10$, type $IIB$ supergravity, using a newly developed method
for the construction of actions with chiral bosons, which implies only a single
scalar non propagating auxiliary field. With the same method we construct also
an action in which the complex two-form gauge potential and its Hodge-dual, a
complex six-form gauge potential, appear in a symmetric way in compatibility
with supersymmetry and Lorentz invariance. The duals of the two physical
scalars of the theory turn out to be described by a $SL(2,R)$ triplet of
eight-forms whose curvatures are constrained by a single linear relation.
  We present also a supersymmetric action in which the basic fields and their
duals, six-form and eight-form potentials, appear in a symmetric way. All these
actions are manifestly invariant under the global $SL(2,R)$-duality group of $D
= 10$, $IIB$ supergravity and are equivalent to each other in that their
dynamics corresponds to the well known equations of motion of $ D=10$, $IIB$
supergravity.",9806140v2
1998-07-28,Supergravity Theories in $D\ge 12$ Coupled to Super p-Branes,"We construct supergravity theories in twelve and thirteen dimensions with the
respective signatures (10,2) and (11,2) with some technical details. Starting
with N=1 supergravity in 10+2 dimensions coupled to Green-Schwarz superstring,
we give N=2 chiral supergravity in 10+2 dimensions with its couplings to super
(2+2)-brane. We also build an N=1 supergravity in 11+2 dimensions, coupled to
supermembrane. All of these formulations utilize scalar (super)fields intact
under supersymmetry, replacing the null-vectors introduced in their original
formulations. This method makes all the equations SO(10,2) or SO(11,2) Lorentz
covariant, up to modified Lorentz generators. We inspect the internal
consistency of these formulations, in particular with the usage of the modified
Lorentz generators for the extra coordinates.",9807199v2
1998-12-12,Relating Green's Functions in Axial and Lorentz Gauges using Finite Field-Dependent BRS Transformations,"We use finite field-dependent BRS transformations (FFBRS) to connect the
Green functions in a set of two otherwise unrelated gauge choices. We choose
the Lorentz and the axial gauges as examples. We show how the Green functions
in axial gauge can be written as a series in terms of those in Lorentz gauges.
Our method also applies to operator Green's functions. We show that this
process involves another set of related FFBRS transfomations that is derivable
from infinitesimal FBRS. We suggest possible applications.",9812101v4
1999-01-09,Quantum Field Theory in Light-Front coordinates,"Canonical formulation of quantum field theory on the Light Front (LF) is
reviewed. The problem of constructing the LF Hamiltonian which gives the theory
equivalent to original Lorentz and gauge invariant one is considered. We
describe possible ways of solving this problem: (a) the limiting transition
from the equal-time Hamiltonian in a fastly moving Lorentz frame to LF
Hamiltonian, (b) the direct comparison of LF perturbation theory in coupling
constant and usual Lorentz-covariant Feynman perturbation theory. Gauge
invariant regularization of LF Hamiltonian via introducing a lattice in
transverse coordinates and imposing periodic boundary conditions in LF
coordinate $x^-$ for gauge fields on the interval $|x^-|< L$ is considered. We
find that LF canonical formalism for this regularization avoid usual most
complicated constraints connecting zero and nonzero modes of gauge fields.",9901029v1
2000-02-21,Pinned Branes and New Non Lorentz Invariant Theories,"We describe a mechanism for localising branes in ambient space. When a 3-form
flux is turned on in a Taub-NUT space, an M5-brane gets an effective potential
that pins it to the center of the space. A similar effect occurs for M2-branes
and D-branes with appropriate fluxes. In carefully chosen limits of the
external parameters, this leads to new theories that are decoupled from gravity
and appear to break Lorentz invariance. For example, we predict the existence
of a new 5+1D theory that breaks Lorentz invariance at high-energy and has a
low-energy description of N tensor multiplets with (1,0) supersymmetry. We also
predict a new type of theory that, similarly to the little-string theory
decouples from gravity by a dynamical (rather than kinematical) argument.",0002175v2
2000-06-23,On covariant $κ-$symmetry fixing and the relation betwen the NSR string and the Type II GS superstring,"By considering the superembedding equation for the Type II superstring we
derive the classical relation between the NSR string and the Type II GS
superstring Grassmannian variables. The connection between the actions of these
two models is also established. Then introducing the proper twistor-like
Lorentz harmonic variables we fix $\kappa-$symmetry of the GS formulation in
the manifestly SO(1,9) Lorentz covariant manner and establish the relation
between the gauge-fixed variables of the NSR and the Type II GS models.",0006185v2
2000-08-15,Lorentz Transformation and Light-Like Noncommutative SYM,"We show that combining the spatial noncommutative SYM limit and Lorentz
transformation, one can obtain a well-behaved light-like noncommutative SYM
limit. The light-like noncommutative SYM is unitary. When the boost velocity is
finite, the resulting theory with space-time noncommutativity is unitary as
well. The light-like noncommutative SYM limit can also be approached by
combining the noncommutative open string theory limit and Lorentz
transformation. Along this line, we obtain the supergravity dual for the
light-like noncommutative SYM, which is the same as the one acquired using a
different method. As a comparison, the supergravity duals for the ordinary SYM,
spatial noncommutative SYM and the noncommutative open string theories are
given as well, in an infinitely-boosted frame with finite momentum density,
which are the decoupling limits of bound states (Dp, W), (D($p-2$), W, Dp), and
(F1, W, Dp), respectively.",0008119v2
2000-09-20,"Interference phenomena, chiral bosons and Lorentz invariance","We have studied the theory of gauged chiral bosons and proposed a general
theory, a master action, that encompasses different kinds of gauge field
couplings in chiral bosonized theories with first-class chiral constraints. We
have fused opposite chiral aspects of this master action using the soldering
formalism and applied the final action to several well known models. The
Lorentz rotation permitted us to fix conditions on the parameters of this
general theory in order to preserve the relativistic invariance. We also have
established some conditions on the arbitrary parameter concerned in a chiral
Schwinger model with a generalized constraint, investigating both covariance
and Lorentz invariance. The results obtained supplements the one that shows the
soldering formalism as a new method of mass generation.",0009157v2
2000-10-06,"Lorentz harmonics and superfield action. D=10, N=1 superstring","We propose a new version of the superfield action for a closed D=10, N=1
superstring where the Lorentz harmonics are used as auxiliary superfields. The
incorporation of Lorentz harmonics into the superfield action makes possible to
obtain superfield constraints of the induced worldsheet supergravity as
equations of motion. Moreover, it becomes evident that a so-called 'Wess-Zumino
part' of the superfield action is basically a Lagrangian form of the
generalized action principle. We propose to use the second Noether theorem to
handle the essential terms in the transformation lows of hidden gauge
symmetries, which remove dynamical degrees of freedom from the Lagrange
multiplier superfield.",0010044v2
2000-10-16,Radiatively Induced Lorentz and CPT Violation in Schwinger Constant Field Approximation,"The Schwinger proper-time method is an effective calculation method,
explicitly gauge invariant and nonperturbative. We make use of this method to
investigate the radiatively induced Lorentz and CPT-violating effects in
quantum electrodynamics when an axial vector interaction term is introduced in
the fermionic sector. The induced Lorentz and CPT-violating Chern-Simons term
coincides with the one obtained using a covariant derivative expansion but
differs from the result usually obtained in other regularization schemes. A
possible ambiguity in the approach is also discussed.",0010129v2
2000-12-07,"Stability, Causality, and Lorentz and CPT Violation","Stability and causality are investigated for quantum field theories
incorporating Lorentz and CPT violation. Explicit calculations in the quadratic
sector of a general renormalizable lagrangian for a massive fermion reveal that
no difficulty arises for low energies if the parameters controlling the
breaking are small, but for high energies either energy positivity or
microcausality is violated in some observer frame. However, this can be avoided
if the lagrangian is the sub-Planck limit of a nonlocal theory with spontaneous
Lorentz and CPT violation. Our analysis supports the stability and causality of
the Lorentz- and CPT-violating standard-model extension that would emerge at
low energies from spontaneous breaking in a realistic string theory.",0012060v1
2001-04-30,On the Spontaneous Breakdown of Lorentz Symmetry in Matrix Models of Superstrings,"In string or M theories, the spontaneous breaking of 10D or 11D Lorentz
symmetry is required to describe our space-time. A direct approach to this
issue is provided by the IIB matrix model. We study its 4D version, which
corresponds to the zero volume limit of 4D super SU(N) Yang-Mills theory. Based
on the moment of inertia as a criterion, spontaneous symmetry breaking (SSB)
seems to occur, so that only one extended direction remains, as first observed
by Bialas, Burda et al. However, using Wilson loops as probes of space-time we
do not observe any sign of SSB in Monte Carlo simulations where N is as large
as 48. This agrees with an earlier observation that the phase of the fermionic
integral, which is absent in the 4D model, should play a crucial role if SSB of
Lorentz symmetry really occurs in the 10D IIB matrix model.",0104260v2
2001-07-24,Teleparallel Complex Gravity as Foundation for Noncommutative Gravity,"We present a teleparallel complex gravity as the foundation for the
formulation of noncommutative gravity theory. The negative energy ghosts in the
conventional formulation with U(1,3) local Lorentz connection no longer exists,
since the local Lorentz invariance is broken down to U(1,3) global Lorentz
symmetry. As desired, our teleparallel complex gravity theory also passes the
key classical test of perihelion advance of Mercury. Based on this result, we
present a lagrangian for the noncommutative teleparallel gravity theory.",0107216v4
2001-10-16,Induced Lorentz-Violating Chern-Simons Term in QED: Uncovering Short Distance Interaction Terms in the Effective Lagrangian without the Shadow of Regularization,"We show that the correctly evaluated effective Lagrangian should include
short-distance interaction terms which have been avoided under the protection
of usual regularization and must be properly identified and reinstated if
regularization is to be removed. They have special physical and mathematical
significance as well as restoring gauge invariance and suppressing divergence
in the effective Lagrangian. The rich structure of the short-distance
interaction terms can open up challenging opportunities where the conventional
regularization with rigid structure is unavailable and inappropriate. It
becomes clear that gauge invariance is preserved with or without regularization
and therefore there is no Lorentz-Violating Chern-Simons term in QED.",0110145v1
2001-10-30,Lorentz and CPT violations from Chern-Simons modifications of QED,"The possibility of a small modification of spinor Quantum Electro-Dynamics is
reconsidered, in which Lorentz and CPT non-covariant kinetic terms for photons
and fermions are present. The corresponding free field theory is carefully
discussed. The finite one-loop parity-odd induced effective action is
unambiguously calculated using the physical cutoff method, which manifestly
encodes the maximal residual symmetry group allowed by the presence of the
Lorentz and CPT breaking axial-vector. This very same induced effective action,
which is different from those ones so far quoted in the Literature, is also
re-derived by means of the dimensional regularization, provided the maximal
residual symmetry is maintained in the enlarged $D$-dimensional space-time. As
a consequence, it turns out that the requirement of keeping the maximal
residual symmetry at the quantum level just corresponds to the physical
renormalization prescription which naturally fixes the one-loop parity-odd
induced effective action.",0110279v3
2001-11-01,On the correspondence between Light-Front Hamiltonian approach and Lorentz-covariant formulation for Quantum Gauge Theory,"The problem of the restoring of the equivalence between Light-Front (LF)
Hamiltonian and conventional Lorentz-covariant formulations of gauge theory is
solved for QED(1+1) and (perturbatively to all orders) for QCD(3+1). For
QED(1+1) the LF Hamiltonian is constructed which reproduces the results of
Lorentz-covariant theory. This is achieved by bosonization of the model and by
analysing the resulting bosonic theory to all orders in the fermion mass. For
QCD(3+1) we describe nonstandard regularization that allows to restore
mentioned equivalence with finite number of counterterms in LF Hamiltonian.",0111009v1
2002-05-02,Quantum group symmetry and particle scattering in (2+1)-dimensional quantum gravity,"Starting with the Chern-Simons formulation of (2+1)-dimensional gravity we
show that the gravitational interactions deform the Poincare symmetry of flat
space-time to a quantum group symmetry. The relevant quantum group is the
quantum double of the universal cover of the (2+1)-dimensional Lorentz group,
or Lorentz double for short. We construct the Hilbert space of two gravitating
particles and use the universal R-matrix of the Lorentz double to derive a
general expression for the scattering cross section of gravitating particles
with spin. In appropriate limits our formula reproduces the semi-classical
scattering formulae found by 't Hooft, Deser, Jackiw and de Sousa Gerbert.",0205021v1
2002-05-10,Seiberg-Witten map for noncommutative super Yang-Mills theory,"In this letter we derive the Seiberg-Witten map for noncommutative super
Yang-Mills theory in Wess-Zumino gauge. Following (and using results of)
hep-th/0108045 we split the observer Lorentz transformations into a covariant
particle Lorentz transformation and a remainder which gives directly the
Seiberg-Witten differential equations. These differential equations lead to a
theta-expansion of the noncommutative super Yang-Mills action which is
invariant under commutative gauge transformations and commutative observer
Lorentz transformation, but not invariant under commutative supersymmetry
transformations: The theta-expansion of noncommutative supersymmetry leads to a
theta-dependent symmetry transformation. For this reason the Seiberg-Witten map
of super Yang-Mills theory cannot be expressed in terms of superfields.",0205094v2
2002-06-06,Gravitational Lorentz Violations from M-Theory,"In an attempt to bridge the gap between M-theory and braneworld
phenomenology, we present various gravitational Lorentz-violating braneworlds
which arise from p-brane systems. Lorentz invariance is still preserved locally
on the braneworld. For certain p-brane intersections, the massless graviton is
quasi-localized. This also results from an M5-brane in a C-field. In the case
of a p-brane perturbed from extremality, the quasi-localized graviton is
massive. For a braneworld arising from global AdS_5, gravitons travel faster
when further in the bulk, thereby apparently traversing distances faster than
light.",0206050v3
2002-10-15,"Octonions, G_2 Symmetry, Generalized Self-Duality and Supersymmetries in Dimensions D \le 8","We establish N=(1/8,1) supersymmetric Yang-Mills vector multiplet with
generalized self-duality in Euclidian eight-dimensions with the original full
SO(8) Lorentz covariance reduced to SO(7). The key ingredient is the usage of
octonion structure constants made compatible with SO(7) covariance and
chirality in 8D. By a simple dimensional reduction together with extra
constraints, we derive N=1/8+7/8 supersymmetric self-dual vector multiplet in
7D with the full SO(7) Lorentz covariance reduced to G_2. We find that extra
constraints needed on fields and supersymmetry parameter are not obtained from
a simple dimensional reduction from 8D. We conjecture that other self-dual
supersymmetric theories in lower dimensions D =6 and 4 with respective reduced
global Lorentz covariances such as SU(3) \subset SO(6) and SU(2) \subset SO(4)
can be obtained in a similar fashion.",0210132v4
2002-12-29,Dimensional Reduction of a Lorentz and CPT-violating Maxwell-Chern-Simons Model,"Taking as starting point a Lorentz and CPT non-invariant Chern-Simons-like
model defined in 1+3 dimensions, we proceed realizing its dimensional reduction
to D=1+2. One then obtains a new planar model, composed by the
Maxwell-Chern-Simons (MCS) sector, a Klein-Gordon massless scalar field, and a
coupling term that mixes the gauge field to the external vector, $v^{\mu}$. In
spite of breaking Lorentz invariance in the particle frame, this model may
preserve the CPT symmetry for a single particular choice of $v^{\mu}$.
Analyzing the dispersion relations, one verifies that the reduced model
exhibits stability, but the causality can be jeopardized by some modes. The
unitarity of the gauge sector is assured without any restriction, while the
scalar sector is unitary only in the space-like case.
  PACS numbers: 11.10.Kk; 11.30.Cp; 11.30.Er; 12.60.-i",0212330v2
2003-01-24,String Theoretic Bounds on Lorentz-Violating Warped Compactification,"We consider warped compactifications that solve the 10 dimensional
supergravity equations of motion at a point, stabilize the position of a
D3-brane world, and admit a warp factor that violates Lorentz invariance along
the brane. This gives a string embedding of ``asymmetrically warped'' models
which we use to calculate stringy (\alpha') corrections to standard model
dispersion relations, paying attention to the maximum speeds for different
particles. We find, from the dispersion relations, limits on gravitational
Lorentz violation in these models, improving on current limits on the speed of
graviton propagation, including those derived from field theoretic loops. We
comment on the viability of models that use asymmetric warping for self-tuning
of the brane cosmological constant.",0301189v3
2003-02-14,The C-Deformation of Gluino and Non-planar Diagrams,"We consider a deformation of N=1 supersymmetric gauge theories in four
dimensions, which we call the C-deformation, where the gluino field satisfies a
Clifford-like algebra dictated by a self-dual two-form, instead of the standard
Grassmannian algebra. The superpotential of the deformed gauge theory is
computed by the full partition function of an associated matrix model (or more
generally a bosonic gauge theory), including non-planar diagrams. In this
identification, the strength of the two-form controls the genus expansion of
the matrix model partition function. For the case of pure N=1 Yang-Mills this
deformation leads to the identification of the all genus partition function of
c=1 non-critical bosonic string at self-dual radius as the glueball
superpotential. Though the C-deformation violates Lorentz invariance, the
deformed F-terms are Lorentz invariant and the Lorentz violation is screened in
the IR.",0302109v2
2003-12-17,Convolution of Lorentz Invariant Ultradistributions and Field Theory,"In this work, a general definition of convolution between two arbitrary four
dimensional Lorentz invariant (fdLi) Tempered Ultradistributions is given, in
both: Minkowskian and Euclidean Space (Spherically symmetric tempered
ultradistributions). The product of two arbitrary fdLi distributions of
exponential type is defined via the convolution of its corresponding Fourier
Transforms. Several examples of convolution of two fdLi Tempered
Ultradistributions are given. In particular we calculate exactly the
convolution of two Feynman's massless propagators. An expression for the
Fourier Transform of a Lorentz invariant Tempered Ultradistribution in terms of
modified Bessel distributions is obtained in this work (Generalization of
Bochner's formula to Minkowskian space). At the same time, and in a previous
step used for the deduction of the convolution formula, we obtain the
generalization to the Minkowskian space, of the dimensional regularization of
the perturbation theory of Green Functions in the Euclidean configuration space
given in ref.[12]. As an example we evaluate the convolution of two
n-dimensional complex-mass Wheeler's propagators.",0312214v1
2004-04-04,Quantization of Field Theory on the Light Front,"Canonical formulation of quantum field theory on the Light Front (LF) is
reviewed. The problem of constructing the LF Hamiltonian which gives the theory
equivalent to original Lorentz and gauge invariant one is considered. We
describe possible ways of solving this problem: (a) the limiting transition
from the equal-time Hamiltonian in a fast moving Lorentz frame to LF
Hamiltonian, (b) the direct comparison of LF perturbation theory in coupling
constant and usual Lorentz-covariant Feynman perturbation theory. The results
of the application of method (b) to QED-1+1 and QCD-3+1 are given. Gauge
invariant regularization of LF Hamiltonian via introducing a lattice in
transverse coordinates and imposing periodic boundary conditions in LF
coordinate x^- for gauge fields on the interval |x^-| smaller than L is also
considered.",0404031v2
2004-05-21,Lorentz-breaking effects in scalar-tensor theories of gravity,"In this work, we study the effects of breaking Lorentz symmetry in
scalar-tensor theories of gravity taking torsion into account. We show that a
space-time with torsion interacting with a Maxwell field by means of a
Chern-Simons-like term is able to explain the optical activity in syncrotron
radiation emitted by cosmological distant radio sources. Without specifying the
source of the dilaton-gravity, we study the dilaton-solution. We analyse the
physical implications of this result in the Jordan-Fierz frame. We also analyse
the effects of the Lorentz breaking in the cosmic string formation process. We
obtain the solution corresponding to a cosmic string in the presence of torsion
by keeping track of the effects of the Chern-Simons coupling and calculate the
charge induced on this cosmic string in this framework. We also show that the
resulting charged cosmic string gives us important effects concerning the
background radiation.The optical activity in this case is also worked out and
discussed.",0405181v1
2004-06-20,"Noncommutative Field Theory on Yang's Space-Time Algebra, Covariant Moyal Star Product and Matrix Model","Noncommutative field theory on Yang's quantized space-time algebra (YSTA) is
studied. It gives a theoretical framework to reformulate the matrix model as
quantum mechanics of $D_0$ branes in a Lorentz-covariant form. The so-called
kinetic term ($\sim {\hat{P_i}}^2)$ and potential term ($\sim
{[\hat{X_i},\hat{X_j}]}^2)$ of $D_0$ branes in the matrix model are described
now in terms of Casimir operator of $SO(D,1)$, a subalgebra of the primary
algebra $SO(D+1,1)$ which underlies YSTA with two contraction- parameters,
$\lambda$ and $R$. $D$-dimensional noncommutative space-time and momentum
operators $\hat{X_\mu}$ and $\hat{P_\mu}$ in YSTA show a distinctive spectral
structure, that is, space-components $\hat{X_i}$ and $\hat{P_i}$ have discrete
eigenvalues, and time-components $\hat{X_0}$ and $\hat{P_0}$ continuous
eigenvalues, consistently with Lorentz-covariance. According to the method of
Lorentz-covariant Moyal star product proper to YSTA, the field equation of
$D_0$ brane on YSTA is derived in a nontrivial form beyond simple Klein-Gordon
equation, which reflects the noncommutative space-time structure of YSTA.",0406166v1
2004-07-13,"Lorentz-violating graviton masses: getting around ghosts, low strong coupling scale and VDVZ discontinuity","A theory with the action combining the Einstein--Hilbert term and graviton
mass terms violating Lorentz invariance is considered at linearized level about
Minkowskian background. It is shown that with one of the masses set equal to
zero, the theory has the following properties: (i) there is a gap of order $m$
in the spectrum, where $m$ is the graviton mass scale; (ii) the dispersion
relations at ${\bf p}^2 \gg m^2$ are $\omega^2 \propto {\bf p}^2$, the spectrum
of tensor modes being relativistic, while other modes having unconventional
maximum velocity; (iii) the VDVZ discontinuity is absent; (iv) the strong
coupling scale is $(mM_{Pl})^{1/2}$. The latter two properties are in sharp
contrast to the Lorentz-invariant gravity with the Pauli--Fierz mass term.",0407104v1
2004-07-29,Lorentz-symmetry Violation and Electrically Charged Vortices in the Planar Regime,"We start from a Lorentz non-invariant Abelian-Higgs model in 1+3 dimensions,
and carry out its dimensional reduction to $D=1+2$. The planar model resulting
thereof is composed by a Maxwell-Chern-Simons-Proca gauge sector, a massive
scalar sector, and a mixing term (involving the fixed background, $v^{\mu}$)
that realizes Lorentz violation for the reduced model. Vortex-type solutions of
the planar model are investigated,revealing charged vortex configurations that
recover the usual Nielsen-Olesen configuration in the asymptotic regime. The
Aharonov-Casher Effect in layered superconductors, that shows interference of
neutral particles with a magnetic moment moving around a line charge, is also
studied. Our charged vortex solutions exhibit a screened electric field that
induces the same phase shift as the one caused by the charged wire.",0407260v3
2004-08-09,On a Lorentz-Invariant Interpretation of Noncommutative Space-Time and Its Implications on Noncommutative QFT,"By invoking the concept of twisted Poincar\' e symmetry of the algebra of
functions on a Minkowski space-time, we demonstrate that the noncommutative
space-time with the commutation relations $[x_\mu,x_\nu]=i\theta_{\mu\nu}$,
where $\theta_{\mu\nu}$ is a {\it constant} real antisymmetric matrix, can be
interpreted in a Lorentz-invariant way. The implications of the twisted
Poincar\'e symmetry on QFT on such a space-time is briefly discussed. The
presence of the twisted symmetry gives justification to all the previous
treatments within NC QFT using Lorentz invariant quantities and the
representations of the usual Poincar\'e symmetry.",0408069v2
2004-09-13,"Strong Equivalence, Lorentz and CPT Violation, Anti-Hydrogen Spectroscopy and Gamma-Ray Burst Polarimetry","The strong equivalence principle, local Lorentz invariance and CPT symmetry
are fundamental ingredients of the quantum field theories used to describe
elementary particle physics. Nevertheless, each may be violated by simple
modifications to the dynamics while apparently preserving the essential
fundamental structure of quantum field theory itself. In this paper, we analyse
the construction of strong equivalence, Lorentz and CPT violating Lagrangians
for QED and review and propose some experimental tests in the fields of
astrophysical polarimetry and precision atomic spectroscopy. In particular,
modifications of the Maxwell action predict a birefringent rotation of the
direction of linearly polarised radiation from synchrotron emission which may
be studied using radio galaxies or, potentially, gamma-ray bursts. In the Dirac
sector, changes in atomic energy levels are predicted which may be probed in
precision spectroscopy of hydrogen and anti-hydrogen atoms, notably in the
Doppler-free, two-photon $1s-2s$ and $2s-nd (n \sim 10)$ transitions.",0409125v1
2004-10-14,Extended Non Linear Conformal Symmetry and DSR Velocities on the Physical Surface,"The relation between Conformal generators and Magueijo Smolin Deformed
Special Relativity term, added to Lorentz boosts, is achieved. The same is
performed for Fock Lorentz transformations. Through a dimensional reduction
procedure, it is demonstrated that a massless relativistic particle living in a
$d$ dimensional space, is isomorphic to one living in a $d+2$ space with pure
Lorentz invariance and to a particle living in a $AdS_{d+1}$ space. To
accomplish these identifications, the Conformal Group is extended and a
nonlinear algebra arises. Finally, because the relation between momenta and
velocities is known, the problem of position space dynamics is solved.",0410159v3
2004-11-26,On the Lorentz symmetry of the noncommutative chiral bosons,"We study issues of Lorentz violation symmetry in the context of the recently
proposed theory of noncommutative fields \cite{CCGM}, using the soldering
formalism. To this end a noncommutative chiral-boson with a deformed algebra
\cite{DGMJ}, used to study these notions in D=2, is properly generalized. We
verify, also for this larger group of theories that, although the structure of
the Lorentz group is preserved, the velocity of light is scaled by a function
of the deformation parameter, as recently claimed. However, we found a sub-set
of models where the velocity of propagation is maintained in spite of the
presence of the deformed algebra. Effects of a preferred-frame of reference
manifest by the presence of birefringence were also studied in the chiral boson
framework leading to the scalar sector of the extended Standard Model recently
proposed.",0411248v3
2004-12-20,Photon as a Vector Goldstone Boson: Nonlinear $σ$ Model for QED,"We show that QED in the Coulomb gauge can be considered as a low energy
linear approximation of a non-linear $\sigma $-type model where the photon
emerges as a vector Goldstone boson related to the spontaneous breakdown of
Lorentz symmetry down to its spatial rotation subgroup at some high scale $M$.
Starting with a general massive vector field theory one naturally arrives at
this model if the pure spin-1 value for the vector field $A_{\mu}(x)$ provided
by the Lorentz condition $\partial_{\mu}A_{\mu}(x)=0$ is required. The model
coincides with conventional QED in the Coulomb gauge in the limit of M going to
infinity and generates a very particular form for the Lorentz and CPT symmetry
breaking terms, which are suppressed by powers of $M$.",0412225v3
2004-12-24,Quantum Gravity and Lorentz invariance violation in the Standard Model,"The most important problem of fundamental Physics is the quantization of the
gravitational field. A main difficulty is the lack of available experimental
tests that discriminate among the theories proposed to quantize gravity.
Recently, Lorentz invariance violation by Quantum Gravity(QG) have been the
source of a growing interest. However, the predictions depend on ad-hoc
hypothesis and too many arbitrary parameters. Here we show that the Standard
Model(SM) itself contains tiny Lorentz invariance violation(LIV) terms coming
from QG. All terms depend on one arbitrary parameter $\alpha$ that set the
scale of QG effects. This parameter can be estimated using data from the Ultra
High Energy Cosmic Rays spectrum to be $|\alpha|<\sim 10^{-22}-10^{-23}$.",0412295v4
2004-12-31,Lorentz-violating massive gauge and gravitational fields,"We study nonlinear dynamics in models of Lorentz-violating massive gravity.
The Boulware-Deser instability restricts severely the class of acceptable
theories. We identify a model that is stable. It exhibits the following bizarre
but interesting property: there are only two massive propagating degrees of
freedom in the spectrum, and yet long-range instantaneous interactions are
present in the theory. We discuss this property on a simpler example of a
photon with a Lorentz-violating mass term where the issues of (a)causality are
easier to understand. Depending on the values of the mass parameter these
models can either be excluded, or become phenomenologically interesting. We
discuss a similar example with more degrees of freedom, as well as a model
without the long-range instantaneous interactions.",0412332v2
2005-01-01,Sfermions and gauginos in a Lorentz-violating theory,"In Lorentz-violating supergravity, sfermions have spin 1/2 and other unusual
properties. If the dark matter consists of such particles, there is a natural
explanation for the apparent absence of cusps and other small scale structure:
The Lorentz-violating dark matter is cold because of the large particle mass,
but still moves at nearly the speed of light. Although the R-parity of a
sfermion, gaugino, or gravitino is +1 in the present theory, these particles
have an ""S-parity'' which implies that the LSP is stable and that they are
produced in pairs. On the other hand, they can be clearly distinguished from
the superpartners of standard supersymmetry by their highly unconventional
properties.",0501003v1
2005-03-18,Gauge Theories with Lorentz-Symmetry Violation by Symplectic Projector Method,"The violation of Lorentz symmetry is studied from the point of view of a
canonical formulation. We make the usual analysis on the constraints structure
of the Carroll-Field-Jackiw model. In this context we derive the equations of
motion for the physical variables and check out the dispersion relations
obtained from them. Therefore, by the analysis using Symplectic Projector
Method (SPM), we can check the results about this type of Lorentz breaking with
those in the recent literature: in this sense we can confirm that the
configuration of $v^{\mu}$ space-like is stable, and the $v^{\mu}$ time-like
carry tachionic modes.",0503145v1
2005-05-11,Killing symmetries of generalized Minkowski spaces. 1-Algebraic-infinitesimal structure of space-time rotation groups,"In this paper, we introduce the concept of N-dimensional generalized
Minkowski space, i.e. a space endowed with a (in general non-diagonal) metric
tensor, whose coefficients do depend on a set of non-metrical coodinates. This
is the first of a series of papers devoted to the investigation of the Killing
symmetries of generalized Minkowski spaces. In particular, we discuss here the
infinitesimal-algebraic structure of the space-time rotations in such spaces.
It is shown that the maximal Killing group of these spaces is the direct
product of a generalized Lorentz group and a generalized translation group. We
derive the explicit form of the generators of the generalized Lorentz group in
the self-representation and their related, generalized Lorentz algebra. The
results obtained are specialized to the case of a 4-dimensional, ''deformed''
Minkowski space $% \widetilde{M_{4}}$, i.e. a pseudoeuclidean space with metric
coefficients depending on energy.",0505088v1
2005-09-04,Poincare Invariance in Multiple D-brane Actions,"We show that the requirement of Poincare invariance (more specifically
invariance under boosts/rotations that mix brane directions with transverse
directions) places severe constraints on the form of actions describing
multiple D-branes, determining an infinite series of correction terms to the
currently known actions. For the case of D0-branes, we argue that up to field
redefinitions, there is a unique Lorentz transformation rule for the coordinate
matrices consistent with the Poincare algebra. We characterize all independent
Poincare invariant structures by describing the leading term of each and
providing an implicit construction of a Poincare invariant completion. Our
construction employs new matrix-valued Lorentz covariant objects built from the
coordinate matrices, which transform simply under the (extremely complicated)
Lorentz transformation rule for the matrix coordinates.",0509026v2
2005-09-22,Towards a High Energy Theory for the Higgs Phase of Gravity,"Spontaneous Lorentz violation due to a time-dependent expectation value for a
massless scalar has been suggested as a method for dynamically generating dark
energy. A natural candidate for the scalar is a Goldstone boson arising from
the spontaneous breaking of a U(1) symmetry. We investigate the low-energy
effective action for such a Goldstone boson in a general class of models
involving only scalars, proving that if the scalars have standard kinetic terms
then at the {\em classical} level the effective action does not have the
required features for spontaneous Lorentz violation to occur asymptotically $(t
\to \infty)$ in an expanding FRW universe. Then we study the large $N$ limit of
a renormalizable field theory with a complex scalar coupled to massive
fermions. In this model an effective action for the Goldstone boson with the
properties required for spontaneous Lorentz violation can be generated.
Although the model has shortcomings, we feel it represents progress towards
finding a high energy completion for the Higgs phase of gravity.",0509180v2
2005-10-18,On Twist Quantizations of D=4 Lorentz and Poincare Algebras,"We use the decomposition of o(3,1)=sl(2;C)_1\oplus sl(2;C)_2 in order to
describe nonstandard quantum deformation of o(3,1) linked with Jordanian
deformation of sl(2;C}. Using twist quantization technique we obtain the
deformed coproducts and antipodes which can be expressed in terms of real
physical Lorentz generators. We describe the extension of the considered
deformation of D=4 Lorentz algebra to the twist deformation of D=4 Poincare
algebra with dimensionless deformation parameter.",0510154v1
2006-02-22,Variational principle and energy-momentum tensor for relativistic Electrodynamics of point charges,"We give a new representation as tempered distribution for the energy-momentum
tensor of a system of charged point-particles, which is free from divergent
self-interactions, manifestly Lorentz-invariant and symmetric, and conserved.
We present a covariant action for this system, that gives rise to the known
Lorentz-Dirac equations for the particles and entails, via Noether theorem,
this energy-momentum tensor. Our action is obtained from the standard action
for classical Electrodynamics, by means of a new Lorentz-invariant
regularization procedure, followed by a renormalization. The method introduced
here extends naturally to charged p-branes and arbitrary dimensions.",0602224v2
2006-04-20,Lorentz-violating corrections on the hydrogen spectrum induced by a non-minimal coupling,"The influence of a Lorentz-violating fixed background on fermions is
considered by means of a torsion-free non-minimal coupling. The
non-relativistic regime is assessed and the Lorentz-violating Hamiltonian is
determined. The effect of this Hamiltonian on the hydrogen spectrum is
determined to first-order evaluation (in the absence of external magnetic
field), revealing that there appear some energy shifts that modify the fine
structure of the spectrum. In the case the non-minimal coupling is
torsion-like, no first order correction shows up in the absence of an external
field; in the presence of an external field, a secondary Zeeman effect is
implied. Such effects are then used to set up stringent bounds on the
parameters of the model.",0604149v1
2006-05-04,"Convolution of Ultradistributions, Field Theory, Lorentz Invariance and Resonances","In this work, a general definition of convolution between two arbitrary
Ultradistributions of Exponential type (UET) is given. The product of two
arbitrary UET is defined via the convolution of its corresponding Fourier
Transforms. Some examples of convolution of two UET are given. Expressions for
the Fourier Transform of spherically symmetric (in Euclidean space) and Lorentz
invariant (in Minkowskian space) UET in term of modified Bessel distributions
are obtained (Generalization of Bochner's theorem). The generalization to UET
of dimensional regularization in configuration space is obtained in both,
Euclidean and Minkowskian spaces As an application of our formalism, we give a
solution to the question of normalization of resonances in Quantum Mechanics.
General formulae for convolution of even, spherically symmetric and Lorentz
invariant UET are obtained and several examples of application are given.",0605058v2
2006-09-29,Lorentz violation in the linearized gravity,"We study some physical consequences of the introduction of a
Lorentz-violating modification term in the linearized gravity, which leads to
modified dispersion relations for gravitational waves in the vacuum. We discuss
two possible mechanisms for the induction of such a term in the Lagrangian.
First, it is generated at the quantum level by a Lorentz-breaking coupling of
the gravity field to a spinor field. Second, it appears as consequence of a
particular modification of the Poisson algebra of the canonical variables, in
the spirit of the so-called ``noncommutative fields approach''.",0609222v4
2007-02-15,Lorentz violation and perpetual motion,"We show that any Lorentz violating theory with two or more propagation speeds
is in conflict with the generalized second law of black hole thermodynamics. We
do this by identifying a classical energy-extraction method, analogous to the
Penrose process, which would decrease the black hole entropy. Although the
usual definitions of black hole entropy are ambiguous in this context, we
require only very mild assumptions about its dependence on the mass. This
extends the result found by Dubovsky and Sibiryakov, which uses the Hawking
effect and applies only if the fields with different propagation speeds
interact just through gravity. We also point out instabilities that could
interfere with their black hole {\it perpetuum mobile}, but argue that these
can be neglected if the black hole mass is sufficiently large.",0702124v2
2006-07-04,Timelike surfaces of constant mean curvature 1 in anti-de Sitter 3-space,"It is shown that timelike surfaces of constant mean curvature 1 in anti-de
Sitter 3-space can be constructed from a pair of Lorentz holomorphic and
Lorentz antiholomorphic null curves in PSL(2,R) via Bryant type representation
formulae. These formulae are used to investigate an explicit one-to-one
correspondence, the so-called Lawson correspondence, between timelike surfaces
of constant mean curvature 1 in anti-de Sitter 3-space and timelike minimal
surfaces in Minkowski 3-space. The hyperbolic Gauss map of timelike surfaces in
anti-de Sitter 3-space, which is a close analogue of the classical Gauss map is
considered. It is discussed that the hyperbolic Gauss map plays an important
role in the study of timelike surfaces of constant mean curvature 1 in anti-de
Sitter 3-space. In particular, the relationship between the Lorentz
holomorphicity of the hyperbolic Gauss map and timelike surfaces of constant
mean curvature 1 in anti-de Sitter 3-space is studied.",0607104v2
2000-09-02,Mass and Spin Renormalization in Lorentz Electrodynamics,"A new, relativistically covariant, massive Lorentz Electrodynamics (LED) is
presented in which the bare particle has a finite positive bare rest mass and
moment of inertia. The particle's electromagnetic self-interaction renormalizes
its mass and spin. Most crucially, the renormalized particle is a soliton:
after any scattering process its rest mass and spin magnitude are dynamically
restored to their pre-scattering values. This guarantees that ``an electron
remains an electron,'' poetically speaking. A renormalization flow study of the
limit of vanishing bare rest mass is conducted for this model. This limit
yields a purely electromagnetic classical field theory with ultra-violet cutoff
at about the electron's Compton wavelength! The renormalized limit model
matches the empirical electron data as orderly as one can hope for at the level
of Lorentz theory. In particular, no superluminal equatorial gyration speeds
occur.",0009003v2
2000-09-15,Translational and Rotational Properties of Antisymmetric Tensor Fields,"Recently, several discussions on the possible observability of 4-vector
potential have been published in literature. Furthermore, several authors
recently claimed existence of the helicity=0 electromagnetic field. We
re-examine the theory of antisymmetric tensor field and 4-vector potentials. We
study the massless limits too. In fact, a theoretical motivation for this
venture is old papers of Ogievetskii and Polubarinov, Hayashi, and Kalb and
Ramond, which are widely accepted by physics community. This paper is based on
two poster presentations ""About the Longitudinal Nature of the Antisymmetric
Tensor Field after Quantization"" and ""Normalization and m->0 Limit of the Proca
Theory"" at the Workshop ""Lorentz Group, CPT and Neutrinos"" (Zacatecas, Mexico,
June 23-26, 1999).",0009024v1
2001-08-31,Wigner Rotations in Laser Cavities,"The Wigner rotation is a key word in many branches of physics, chemistry and
engineering sciences. It is a group theoretical effect resulting from two
Lorentz boosts. The net effect is one boost followed or preceded by a rotation.
This rotation can therefore be formulated as a product of three boosts. In
relativistic kinematics, it is a rotation in the Lorentz frame where the
particle is at rest. This rotation does not change its momentum, but it rotates
the direction of the spin. The Wigner rotation is not confined to relativistic
kinematics. It manifests itself in physical systems where the underlying
mathematics is the Lorentz group. It is by now widely known that this group is
the basic scientific language for quantum and classical optics. It is shown
that optical beams perform Wigner rotations in laser cavities.",0108028v1
2002-09-19,General Solutions of Relativistic Wave Equations,"General solutions of relativistic wave equations are studied in terms of the
functions on the Lorentz group. A close relationship between hyperspherical
functions and matrix elements of irreducible representations of the Lorentz
group is established. A generalization of the Gel'fand-Yaglom formalism for
higher-spin equations is given. It is shown that a two-dimensional complex
sphere is associated with the each point of Minkowski spacetime. The separation
of variables in a general relativistically invariant system is obtained via the
hyperspherical functions defined on the surface of the two-dimensional complex
sphere. In virtue of this, the wave functions are represented in the form of
series on the hyperspherical functions. Such a description allows to consider
all the physical fields on an equal footing. General solutions of the Dirac and
Weyl equations, and also the Maxwell equations in the Majorana-Oppenheimer
form, are given in terms of the functions on the Lorentz group.",0209036v1
2003-10-31,"Wigner's new physics frontier: Physics of two-by-two matrices, including the Lorentz group and optical instruments","According to Eugene Wigner, quantum mechanics is a physics of Fourier
transformations, and special relativity is a physics of Lorentz
transformations. Since two-by-two matrices with unit determinant form the group
SL(2,c) which acts as the universal covering group of the Lorentz group, the
two-by-two matrices constitute the natural language for special relativity. The
central language for optical instruments is the two-by-two matrix called the
beam transfer matrix, or the so-called ABCD matrix. It is shown that the ABCD
matrices also form the SL(2,C) group. Thus, it is possible to perform
experiments in special relativity using optical instruments. Likewise, the
optical instruments can be explained in terms of the symmetry of relativistic
particles.",0310068v1
2004-01-15,Rotations associated with Lorentz boosts,"It is possible to associate two angles with two successive non-collinear
Lorentz boosts. If one boost is applied after the initial boost, the result is
the final boost preceded by a rotation called the Wigner rotation. The other
rotation is associated with Wigner's O(3)-like little group. These two angles
are shown to be different. However, it is shown that the sum of these two
rotation angles is equal to the angle between the initial and final boosts.
This relation is studied for both low-speed and high-speed limits. Furthermore,
it is noted that the two-by-two matrices which are under the responsibility of
other branches of physics can be interpreted in terms of the transformations of
the Lorentz group, or vice versa. Classical ray optics is mentioned as a case
in point.",0401032v1
2003-12-22,Thermodynamic formalism for field driven Lorentz gases,"We analytically determine the dynamical properties of two dimensional field
driven Lorentz gases within the thermodynamic formalism. For dilute gases
subjected to an iso-kinetic thermostat, we calculate the topological pressure
as a function of a temperature-like parameter $\ba$ up to second order in the
strength of the applied field. The Kolmogorov-Sinai entropy and the topological
entropy can be extracted from a dynamical entropy defined as a Legendre
transform of the topological pressure. Our calculations of the Kolmogorov-Sinai
entropy exactly agree with previous calculations based on a Lorentz-Boltzmann
equation approach. We give analytic results for the topological entropy and
calculate the dimension spectrum from the dynamical entropy function.",0312053v1
2004-04-16,The Lyapunov spectrum of the many-dimensional dilute random Lorentz gas,"For a better understanding of the chaotic behavior of systems of many moving
particles it is useful to look at other systems with many degrees of freedom.
An interesting example is the high-dimensional Lorentz gas, which, just like a
system of moving hard spheres, may be interpreted as a dynamical system
consisting of a point particle in a high-dimensional phase space, moving among
fixed scatterers. In this paper, we calculate the full spectrum of Lyapunov
exponents for the dilute random Lorentz gas in an arbitrary number of
dimensions. We find that the spectrum becomes flatter with increasing
dimensionality. Furthermore, for fixed collision frequency the separation
between the largest Lyapunov exponent and the second largest one increases
logarithmically with dimensionality, whereas the separations between Lyapunov
exponents of given indices not involving the largest one, go to fixed limits.",0404034v1
2004-11-12,Thermodynamic formalism for the Lorentz gas with open boundaries in $d$ dimensions,"A Lorentz gas may be defined as a system of fixed dispersing scatterers, with
a single light particle moving among these and making specular collisions on
encounters with the scatterers. For a dilute Lorentz gas with open boundaries
in $d$ dimensions we relate the thermodynamic formalism to a random flight
problem. Using this representation we analytically calculate the central
quantity within this formalism, the topological pressure, as a function of
system size and a temperature-like parameter $\ba$. The topological pressure is
given as the sum of the topological pressure for the closed system and a
diffusion term with a $\ba$-dependent diffusion coefficient. From the
topological pressure we obtain the Kolmogorov-Sinai entropy on the repeller,
the topological entropy, and the partial information dimension.",0411032v1
2004-11-18,Entropy production in diffusion-reaction systems: The reactive random Lorentz gas,"We report the study of a random Lorentz gas with a reaction of isomerization
$A\rightleftharpoons B$ between the two colors of moving particles elastically
bouncing on hard disks. The reaction occurs when the moving particles collide
on catalytic disks which constitute a fraction of all the disks. Under the
dilute-gas conditions, the reaction-diffusion process is ruled by two coupled
Boltzmann-Lorentz equations for the distribution functions of the colors. The
macroscopic reaction-diffusion equations with cross-diffusion terms induced by
the chemical reaction are derived from the kinetic equations. We use a
$H$-theorem of the kinetic theory in order to derive a macroscopic entropy
depending on the gradients of color densities and which has a non-negative
entropy production in agreement with the second law of thermodynamics.",0411041v2
1994-02-10,On the Lorentz structure of the confinement potential,"We investigate the Lorentz structure of the confinement potential through a
study of the meson spectrum using Salpeter's instantaneous approximation to the
Bethe-Salpeter equation. The equivalence between Salpeter's and a
random-phase-approximation (RPA) equation enables one to employ the same
techniques developed by Thouless, in his study of nuclear collective
excitations, to test the stability of the solutions. The stablity analysis
reveals the existence of imaginary eigenvalues for a confining potential that
transforms as a Lorentz scalar. Moreover, we argue that the instability
persists even for very large values of the constituent quark mass. In contrast,
we find no evidence of imaginary eigenvalues for a timelike vector potential
--- even for very small values of the constituent mass.",9402019v1
1996-09-09,Baryon Density and the Dilated Chiral Quark Model,"We calculate perturbatively the effect of density on hadronic properties
using the chiral quark model implemented by the QCD trace anomaly to see the
possibility of constructing Lorentz invariant Lagrangian at finite density. We
calculate the density dependent masses of the constituent quark, the scalar
field and the pion in one-loop order using the technique of thermo field
dynamics. In the chiral limit, the pion remains massless at finite density. It
is found that the tadpole type corrections lead to the decreasing masses with
increasing baryon density, while the radiative corrections induce
Lorentz-symmetry-breaking terms. We found in the large $N_c$ limit with large
scalar mass that the tadpoles dominate and the mean-field approximation is
reliable, giving rise a Lorentz-invariant Lagrangian with masses decreasing as
the baryon density increases.",9609020v2
1997-12-22,Lorentz Multiplet Structure of Baryon Spectra and Relativistic Description,"The pole positions of the various baryon resonances are known to reveal
well-pronounced clustering, so-called Hoehler clusters. For nonstrange baryons
the Hoehler clusters are shown to be identical to Lorentz multiplets of the
type (j,j)*[(1/2,0)+(0,1/2)] with j being a half-integer. For the Lambda
hyperons below 1800 MeV these clusters are shown to be of the type [(1,0)+
(0,1)]*[(1/2,0)+(0,1/2)] while above 1800 MeV they are parity duplicated
(J,0)+(0,J) (Weinberg-Ahluwalia) states. Therefore, for Lambda hyperons the
restoration of chiral symmetry takes place above 1800 MeV. Finally, it is
demonstrated that the description of spin-3/2 particles in terms of a 2nd rank
antisymmetric Lorentz tensor with Dirac spinor components does not contain any
off-shell parameters and avoids the main difficulties of the Rarita-Schwinger
description based upon a 4-vector with Dirac spinor components.",9712072v1
2002-08-15,Lorentz Boosted NN Potential for Few-Body Systems: Application to the three-nucleon bound state,"A Lorentz boosted two-nucleon potential is introduced in the context of equal
time relativistic quantum mechanics. The dynamical input for the boosted
nucleon-nucleon (NN) potential is based on realistic NN potentials, which by a
suitable scaling of the momenta are transformed into NN potentials belonging to
a relativistic two-nucleon Schroedinger equation in the c.m. system. This
resulting Lorentz boosted potential is consistent with a previously introduced
boosted two-body t-matrix. It is applied in relativistic Faddeev equations for
the three-nucleon bound state to calculate the ^3H binding energy. Like in
previous calculations the boost effects for the two-body subsystems are
repulsive and lower the binding energy.",0208029v2
2003-09-10,On the Lorentz structure of the symmetry energy,"We investigate in detail the density dependence of the symmetry energy in a
relativistic description by decomposing the iso-vector mean field into
contributions with different Lorentz covariant properties. We find important
effects of the iso-vector, scalar channel (i.e. $\delta$-meson like) on the
high density behavior of the symmetry energy. Applications to static properties
of finite nuclei and to dynamic situations of heavy ion collisions are explored
and related to each other. The nuclear structure studies show only moderate
effects originating from the virtual $\delta$ meson. At variance, in heavy ion
collisions one finds important contributions on the reaction dynamics arising
from the different Lorentz structure of the high density symmetry energy when a
scalar iso-vector $\delta$ field is introduced. Particularly interesting is the
related neutron/proton effective mass splitting for nucleon transport effects
and for resonance and particle production around the threshold. We show that
the $\delta$-like channel turns out to be essential for the production of
pions, when comparing with experimental data, in particular for high momentum
selections.",0309021v1
2003-12-17,Sensitivity of exclusive proton knockout spin observables to different Lorentz invariant representations of the NN interaction,"Within the framework of the relativistic plane wave impulse approximation, we
study the observable consequences of employing a complete Lorentz invariant
representation of the NN scattering matrix in terms of 44 independent
amplitudes, as opposed to the previously-employed, but ambiguous, five-term
Lorentz invariant parametrization of the NN scattering matrix, for the
prediction of complete sets of exclusive ($\vec{p},2 \vec{p} $) polarization
transfer observables. Two kinematic conditions are considered, namely proton
knockout from the $3s_{1/2}$ state of $^{208}$Pb at an incident energy of 202
MeV for coplanar scattering angles ($28.0^{\circ}, -54.6^{\circ}$), as well as
an incident energy of 392 MeV for the angle pair ($32.5^{\circ},
-80.0^{\circ}$). The results indicate that certain spin observables are ideal
for discriminating between the two representations.",0312066v1
1997-06-23,Possible Effects of Lorentz Symmetry Violation on the Interaction Properties of Very High-Energy Cosmic Rays,"Special relativity has been tested at low energy with great accuracy, but
these results cannot be extrapolated to the very high-energy region.
Introducing a critical distance scale, $a$ , below 10E-25 cm (the wavelength
scale of the highest-energy observed cosmic rays) allows to consider models,
compatible with standard tests of special relativity, where a small violation
of Lorentz symmetry ($a$ can, for instance, be the Planck length, around 10E-33
cm) produces dramatic effects on the interaction properties of very high-energy
particles. Lorentz symmetry violation may potentially solve all the basic
problems raised by the highest-energy cosmic rays (origin and energy,
propagation...). Furthermore, superluminal sectors of matter may exist and
release very high-energy ordinary particles or directly produce very
high-energy cosmic-ray events with unambiguous signatures in very large
detectors. We discuss these phenomena, as well as the cosmic-ray energy range
(well below the energy scale associated to the fundamental length) and
experiments where they could be detected and studied.",9706032v1
1997-07-20,Stokes Parameters as a Minkowskian Four-vector,"It is noted that the Jones-matrix formalism for polarization optics is a
six-parameter two-by-two representation of the Lorentz group. It is shown that
the four independent Stokes parameters form a Minkowskian four-vector, just
like the energy-momentum four-vector in special relativity. The optical filters
are represented by four-by-four Lorentz-transformation matrices. This
four-by-four formalism can deal with partial coherence described by the Stokes
parameters. A four-by-four matrix formulation is given for decoherence effects
on the Stokes parameters, and a possible experiment is proposed. It is shown
also that this Lorentz-group formalism leads to optical filters with a symmetry
property corresponding to that of two-dimensional Euclidean transformations.",9707016v1
1999-02-18,Space Time Measurements in Special Relativity,"The conventional discussion of apparent distortions of space and time in
Special Relativity (the Lorentz-Fitzgerald Contraction and Time Dilatation) is
extended by considering observations of : (i) moving objects of limited
lifetime in their own rest frame (`transient luminous objects') and (ii) a
moving extended array of synchronised `equivalent clocks' in a common inertial
frame. Application of the Lorentz Transformation to (i) shows that such
objects, viewed with coarse time resolution, appear to be longer in the
direction of the relative velocity $\vec{v}$ by a factor $1/\sqrt{1-(v/c)^2}$
(Space Dilatation) and to (ii) that the moving equivalent clock that appears at
any fixed position in the rest frame of an inertial observer appears to be
running faster than a similar clock at rest by the factor $1/\sqrt{1-(v/c)^2}$
(Time Contraction).
  The actual appearance of moving objects and clocks, taking into account light
propagation time delays, as well as the effect of the Lorentz Transformation,
is also discussed.",9902048v1
1999-11-12,Is the Lorentz Transformation Distance-Dependent?,"An analysis of the Lorentz transformation shows that the unchangeability of
the space-time coordinates of the inertial systems under consideration and the
possibility of a direct projection of those coordinates onto another are the
underlying assumptions as to its unlimited validity. It is demonstrated that
from a empiric-physical point of view these assumptions are not given in the
case of inertial systems separated by very large distances. Analogous to the
impossibility to measure motion relative to absolute space, it turns out to be
physically non feasible to extend the coordinate system of any reference frame
considered at rest relative to a distantly moving system for a direct
comparision of the coordinates, and vice versa. The extended Lorentz
transformation strictly based on first physical principles predicts the
possibility of superluminal propagation of very distant material bodies and, in
this case, the generation of Cerenkov radiation out of the quantum vacuum. For
many astrophysical phenomena and their experimentally verified properties this
yields a novel view.",9911022v1
2000-07-11,True Transformations of Spacetime Lengths and Apparent Transformations of Spatial and Temporal Distances. I. the Theory,"It is shown in this paper that the difference between the two forms of
relativity - the ''true transformation (TT) relativity'' and - the ''apparent
transformation (AT) relativity'' is essentially caused by the difference in the
concept of \emph{sameness} of a physical system, i.e., of a physical quantity,
for different, relatively moving, observers. In the ''TT relativity'' the same
quantity for different inertial frames of reference is covariantly defined
four-dimensional (4D) tensor quantity, which transforms according to the
Lorentz transformation as the TT. In the ''AT relativity'' parts of a 4D tensor
quantity are often considered as the same quantity for different observers,
although they correspond to different quantities in 4D spacetime, and they are
not connected by the Lorentz transformation than by the AT. Then the true
transformations of a spacetime length and the apparent transformations of a
spatial distance (the Lorentz contraction) and of a temporal distance (the
usual dilatation of time) are examined in detail. It is proved that only the
true transformations of the spacetime length are in agreement with the special
relativity as the theory of a 4D spacetime with the pseudo-Euclidean geometry.",0007030v1
2001-03-22,Testing Lorentz and CPT symmetry with hydrogen masers,"We present details from a recent test of Lorentz and CPT symmetry using
hydrogen masers. We have placed a new limit on Lorentz and CPT violation of the
proton in terms of a recent standard model extension by placing a bound on
sidereal variation of the F = 1 Zeeman frequency in hydrogen. Here, the
theoretical standard model extension is reviewed. The operating principles of
the maser and the double resonance technique used to measure the Zeeman
frequency are discussed. The characterization of systematic effects is
described, and the method of data analysis is presented. We compare our result
to other recent experiments, and discuss potential steps to improve our
measurement.",0103068v1
2003-08-08,On the meaning of Lorentz covariance,"In classical mechanics, Galilean covariance and the principle of relativity
are completely equivalent and hold for all possible dynamical processes. In
contrast, in relativistic physics the situation is much more complex. It will
be shown that Lorentz covariance and the principle of relativity are not
completely equivalent. The reason is that the principle of relativity actually
only holds for the equilibrium quantities that characterize the equilibrium
state of dissipative systems. In the light of this fact it will be argued that
Lorentz covariance should not be regarded as a fundamental symmetry of the laws
of physics.",0308036v4
2004-11-04,Special Relativity: Einstein's Spherical Waves versus Poincare's Ellipsoidal Waves,"We show that the image by the Lorentz transformation of a spherical
(circular) light wave, emitted by a moving source, is not a spherical
(circular) light wave but an ellipsoidal (elliptical) light wave. Poincare's
ellipsoid (ellipse) is the direct geometrical representation of Poincare's
relativity of simultaneity. Einstein's spheres (circles) are the direct
geometrical representation of Einstein's convention of synchronisation.
Poincare adopts another convention for the definition of space-time units
involving that the Lorentz transformation of an unit of length is directly
proportional to Lorentz transformation of an unit of time. Poincare's
relativistic kinematics predicts both a dilation of time and an expansion of
space as well.",0411045v2
2004-12-06,Extraction of electric field in heavily irradiated silicon pixel sensors,"A new method for the extraction of the electric field in the bulk of heavily
irradiated silicon pixel sensors is presented. It is based on the measurement
of the Lorentz deflection and mobility of electrons as a function of depth. The
measurements were made at the CERN H2 beam line, with the beam at a shallow
angle with respect to the pixel sensor surface. The extracted electric field is
used to simulate the charge collection and the Lorentz deflection in the pixel
sensor. The simulated charge collection and the Lorentz deflection is in good
agreement with the measurements both for non-irradiated and irradiated up to
1E15 neq/cm2 sensors.",0412036v2
2005-06-28,Frequent Errors in Special Relativity,"Some reasons are given to suggest that the interpretation of the Lorentz'
transformations as if they referred to coordinates instead of to intervals
could be incorrect. Besides, the usual form of such transformations, by using
variables that represent finite values instead of differentials, could be
another error. Later it is shown that the Lorentz contraction factor must not
have the form currently accepted for it if the Lorentz contraction factor is
assumed to be equal to the quotient between time differentials.",0506207v3
2005-09-01,"Lorentz, Edwards transformations and the principle of permutation invariance","The Lorentz transformation is derived without the postulate of the universal
limiting speed, and the general Edwards transformation is obtained by using the
principle of permutation invariance (covariance). It is shown that the
existences of the one-way universal limiting speed (in the Lorentz
transformation) and the constancy of the two-way average speed of light (in the
Edwards transformation) are the necessary consequences of the principle of
permutation invariance that is consistent with the postulate of relativity. The
connection between the Edward transformation and the general coordinate
transformation is discussed, and based on this, we find that the physical
meaning of the Edward parameter, which indicates the anisotropy of the speed of
light, is a gravitomagnetic potential of the spacetime.",0509012v1
2006-02-20,Are We Observing Violations of Lorentz Symmetry?,"Recent observations of ultra high energy cosmic rays and gamma rays suggest
that there are small violations of Lorentz symmetry. If there were no such
violations, then the GZK cut off would hold and cosmic rays with energy $\sim
10^{20}eV$ or higher would not be reaching the earth. However some such events
seem to have been observed. This has lead to phenomenological models in which
there is a small violation of the Lorentz symmetry or the velocity of light.
However recent Quantum Gravity and String Theory approaches which no longer
consider a differentiable spacetime manifold already predict such violations.
Similarly there are other theoretical reasons which also point to this. We
briefly discuss the various possibilities.",0602132v1
2006-03-02,Lorentz Transformation as a 'Complementary Time-Dependent Coordinate Transformation'. The Physical Foundation of Einstein' Special Relativity,"We here deduce Lorentz transformation (LT) as a member of a class of
time-dependent coordinate transformations, complementary to those already known
as spatial translations and rotations. This exercise validates the principle of
physical determination of equations within special relativity theory (SRT), in
accordance with the derivation of the LT in Einstein's original paper on
relativity. This validation is possible because our LT deduction also discloses
the real physics warranting Einstein's manipulations of several equations in
that paper, thus proving the correctness of his derivation of the LT. The
essential role of the revelation in the act of science then results. Far from
being an arbitrary dogmatic construction, SRT appears to be a revealed dogmatic
theory that can be turned into a truly physical one like operational theory.
Radically new technological applications of relativistic quantum theory then
results.",0603015v2
2006-06-20,The Lorentz Transformation for Photons in Dispersive Media and in Gravitational Fields,"It is pointed out that the traditional explanation for the observation of a
non-zero energy h nu for light in free space does not apply for the analogous
situation in dispersive media. Because the speed of light u is no longer equal
to c in this case, the key quantity, gamma = (1-u2/c2)-0.5, is finite as a
result. Since the rest energy of photons is believed to always be equal to
zero, multiplying it with gamma in analogy to the usual procedure employed in
the special theory of relativity (STR) does not produce a nonzero result for
photons in dispersive media. The experimental evidence of the Fizeau light-drag
and Cerenkov radiation phenomena indicate that the Lorentz transformation in
free space is nonetheless valid for light in dispersive media. Instead, the
energy and momentum of photons in transparent media can be obtained from
observations of the frequency, wavelength and index of refraction of the light.
A modification of the Lorentz transformation in which the observed speed of
light does appear explicitly is required, however, in order to accurately
predict the results of measurements made when the observer is at a different
gravitational potential than the object.",0606172v1
2006-10-03,Some Variations on Maxwell's Equations,"In the first sections of this article, we discuss two variations on Maxwell's
equations that have been introduced in earlier work--a class of nonlinear
Maxwell theories with well-defined Galilean limits (and correspondingly
generalized Yang-Mills equations), and a linear modification motivated by the
coupling of the electromagnetic potential with a certain nonlinear Schroedinger
equation. In the final section, revisiting an old idea of Lorentz, we write
Maxwell's equations for a theory in which the electrostatic force of repulsion
between like charges differs fundamentally in magnitude from the electrostatic
force of attraction between unlike charges. We elaborate on Lorentz'
description by means of electric and magnetic field strengths, whose governing
equations separate into two fully relativistic Maxwell systems--one describing
ordinary electromagnetism, and the other describing a universally attractive or
repulsive long-range force. If such a force cannot be ruled out {\it a priori}
by known physical principles, its magnitude should be determined or bounded
experimentally. Were it to exist, interesting possibilities go beyond Lorentz'
early conjecture of a relation to (Newtonian) gravity.",0610020v2
1995-07-07,"Generalized uncertainty relations: Theory, examples, and Lorentz invariance","The quantum-mechanical framework in which observables are associated with
Hermitian operators is too narrow to discuss measurements of such important
physical quantities as elapsed time or harmonic-oscillator phase. We introduce
a broader framework that allows us to derive quantum-mechanical limits on the
precision to which a parameter---e.g., elapsed time---may be determined via
arbitrary data analysis of arbitrary measurements on $N$ identically prepared
quantum systems. The limits are expressed as generalized Mandelstam-Tamm
uncertainty relations, which involve the operator that generates displacements
of the parameter---e.g., the Hamiltonian operator in the case of elapsed time.
This approach avoids entirely the problem of associating a Hermitian operator
with the parameter. We illustrate the general formalism, first, with
nonrelativistic uncertainty relations for spatial displacement and momentum,
harmonic-oscillator phase and number of quanta, and time and energy and,
second, with Lorentz-invariant uncertainty relations involving the displacement
and Lorentz-rotation parameters of the Poincar\'e group.",9507004v1
1996-10-13,Wavelets and Information-preserving Transformations,"The underlying mathematics of the wavelet formalism is a representation of
the inhomogeneous Lorentz group or the affine group. Within the framework of
wavelets, it is possible to define the ``window'' which allows us to introduce
a Lorentz-covariant cut-off procedure. The window plays the central role in
tackling the problem of photon localization. It is possible to make a
transition from light waves to photons through the window. On the other hand,
the windowed wave function loses analyticity. This loss of analyticity can be
measured in terms of entropy difference. It is shown that this entropy
difference can be defined in a Lorentz-invariant manner within the framework of
the wavelet formalism.",9610018v1
1997-10-28,Does Lorentz Boost Destroy Coherence?,"It is shown that the time-energy uncertainty relation can be combined into
the position-momentum uncertainty relation covariantly in the quark model of
hadrons. This leads to a Lorentz-invariant form of the uncertainty relations.
This model explains that the quark model and the parton model are two different
manifestations of the same covariant model. In particular, this covariant model
explains why the coherent amplitudes in the quark model become incoherent,
after a Lorentz boost, in the parton model. It is shown that this lack of
coherence is consistent with the present form of quantum mechanics.",9710062v1
1998-01-30,Hypersurface Bohm-Dirac models,"We define a class of Lorentz invariant Bohmian quantum models for N entangled
but noninteracting Dirac particles. Lorentz invariance is achieved for these
models through the incorporation of an additional dynamical space-time
structure provided by a foliation of space-time. These models can be regarded
as the extension of Bohm's model for N Dirac particles, corresponding to the
foliation into the equal-time hyperplanes for a distinguished Lorentz frame, to
more general foliations. As with Bohm's model, there exists for these models an
equivariant measure on the leaves of the foliation. This makes possible a
simple statistical analysis of position correlations analogous to the
equilibrium analysis for (the nonrelativistic) Bohmian mechanics.",9801070v2
2002-03-12,Lorentz Invariance of Entanglement,"We study the transformation of maximally entangled states under the action of
Lorentz transformations in a fully relativistic setting. By explicit
calculation of the Wigner rotation, we describe the relativistic analog of the
Bell states as viewed from two inertial frames moving with constant velocity
with respect to each other. Though the finite dimensional matrices describing
the Lorentz transformations are non-unitary, each single particle state of the
entangled pair undergoes an effective, momentum dependent, local unitary
rotation, thereby preserving the entanglement fidelity of the bipartite state.
The details of how these unitary transformations are manifested are explicitly
worked out for the Bell states comprised of massive spin 1/2 particles and
massless photon polarizations. The relevance of this work to non-inertial
frames is briefly discussed.",0203051v1
2002-04-26,Einstein-Podolsky-Rosen Correlations of Spin Measurements in Two Moving Inertial Frames,"The formula for the correlation function of spin measurements of two
particles in two moving inertial frames is derived within Lorentz-covariant
quantum-mechanics formulated in the absolute synchronization framework. The
results are the first exact Einstein-Podolsky-Rosen correlation functions
obtained for Lorentz-covariant quantum-mechanical system in moving frames under
physically acceptable conditions, i.e., taking into account the localization of
the particles during the detection and using the spin opeartor with proper
transformation properties under the action of the Lorentz group. Some special
cases and approximations of the calculated correlation function are given. The
resulting correlation function can be used as a basis for a proposal of a
decisive experiment for a possible existence of a quantum-mechanical preferred
frame.",0204155v2
2002-05-29,Quantum Entanglement of Moving Bodies,"We study the properties of quantum information and quantum entanglement in
moving frames. We show that the entanglement between the spins and the momenta
of two particles can be interchanged under a Lorentz transformation, so that a
pair of particles that is entangled in spin but not momentum in one reference
frame, may, in another frame, be entangled in momentum at the expense of
spin-entanglement. Similarly, entanglement between momenta may be transferred
to spin under a Lorentz transformation. While spin and momentum entanglement
each is not Lorentz invariant, the joint entanglement of the wave function is.",0205179v4
2002-12-24,A Note on the correspondence between Qubit Quantum Operations and Special Relativity,"We exploit a well-known isomorphism between complex hermitian $2\times 2$
matrices and $\mathbb{R}^4$, which yields a convenient real vector
representation of qubit states. Because these do not need to be normalized we
find that they map onto a Minkowskian future cone in $\mathbb{E}^{1,3}$, whose
vertical cross-sections are nothing but Bloch spheres. Pure states are
represented by light-like vectors, unitary operations correspond to special
orthogonal transforms about the axis of the cone, positive operations
correspond to pure Lorentz boosts. We formalize the equivalence between the
generalized measurement formalism on qubit states and the Lorentz
transformations of special relativity, or more precisely elements of the
restricted Lorentz group together with future-directed null boosts. The note
ends with a discussion of the equivalence and some of its possible
consequences.",0212135v3
2003-01-29,Is the concept of quantum probability consistent with Lorentz covariance?,"Lorentz-covariant harmonic oscillator wave functions are constructed from the
Lorentz-invariant oscillator differential equation of Feynman, Kislinger, and
Ravndal for a two-body bound state. The wave functions are not invariant but
covariant. As the differential equation contains the time-separation variable,
the wave functions contain the same time-separation variable which does not
exist in Schr\""odinger wave functions. This time-separation variable can be
shown to belong to Feynman's rest of the universe, and can thus be eliminated
from the density matrix. The covariant probability interpretation is given.
This oscillator formalism explains Feynman's decoherence mechanism which is
exhibited in Feynman's parton picture.",0301155v1
2004-09-02,Common Space of Spin and Spacetime,"Given Lorentz invariance in Minkowski spacetime, we investigate a common
space of spin and spacetime. To obtain a finite spinor representation of the
non-compact homogeneous Lorentz group including Lorentz boosts, we introduce an
indefinite inner product space (IIPS) with a normalized positive probability.
In this IIPS, the common momentum and common variable of a massive fermion turn
out to be ``doubly strict plus-operators''. Due to this nice property, it is
straightforward to show an uncertainty relation between fermion mass and proper
time. Also in IIPS, the newly-defined Lagrangian operators are self-adjoint,
and the fermion field equations are derivable from the Lagrangians. Finally,
the nonlinear QED equations and Lagrangians are presented as an example.",0409011v4
2007-04-16,Global-String and Vortex Superfluids in a Supersymmetric Scenario,"The main goal of this work is to investigate the possibility of finding the
supersymmetric version of the U(1)-global string model which behaves as a
vortex-superfluid. To describe the superfluid phase, we introduce a
Lorentz-symmetry breaking background that, in an approach based on
supersymmetry, leads to a discussion on the relation between the violation of
Lorentz symmetry and explicit soft supersymmetry breakings. We also study the
relation between the string configuration and the vortex-superfluid phase. In
the framework we settle down in terms of superspace and superfields, we
actually establish a duality between the vortex degrees of freedom and the
component fields of the Kalb-Ramond superfield. We make also considerations
about the fermionic excitations that may appear in connection with the vortex
formation.",0704.1935v3
2007-05-07,Synchrotron Radiation in the Standard Model Extension,"We obtain a system of exact solutions of the Dirac equation for an electron
moving in a constant homogeneous external magnetic field with account of its
vacuum magnetic moment and assumed Lorentz invariance violation in the minimal
CPT-odd form in the framework of the Standard Model Extension. Using these
solutions, characteristics of the particle synchrotron radiation are
calculated, and possible observable effects caused by the Lorentz non-invariant
interaction are described. We demonstrate that the angular distribution of the
radiation has specific asymmetry, which can be explained as a consequence of
non-conservation of transversal electron polarization in the presence of a
background Lorentz non-invariant condensate field.",0705.0882v2
2007-05-31,"Semi-Lorentz invariance, unitarity, and critical exponents of symplectic fermion models","We study a model of N-component complex fermions with a kinetic term that is
second order in derivatives. This symplectic fermion model has an Sp(2N)
symmetry, which for any N contains an SO(3) subgroup that can be identified
with rotational spin of spin-1/2 particles. Since the spin-1/2 representation
is not promoted to a representation of the Lorentz group, the model is not
fully Lorentz invariant, although it has a relativistic dispersion relation.
The hamiltonian is pseudo-hermitian, H^\dagger = C H C, which implies it has a
unitary time evolution. Renormalization-group analysis shows the model has a
low-energy fixed point that is a fermionic version of the Wilson-Fisher fixed
points. The critical exponents are computed to two-loop order. Possible
applications to condensed matter physics in 3 space-time dimensions are
discussed.",0705.4657v2
2007-06-29,The distribution of free path lengths in the periodic Lorentz gas and related lattice point problems,"The periodic Lorentz gas describes the dynamics of a point particle in a
periodic array of spherical scatterers, and is one of the fundamental models
for chaotic diffusion. In the present paper we investigate the Boltzmann-Grad
limit, where the radius of each scatterer tends to zero, and prove the
existence of a limiting distribution for the free path length of the periodic
Lorentz gas. We also discuss related problems, such as the statistical
distribution of directions of lattice points that are visible from a fixed
position.",0706.4395v2
2007-07-18,New constraints on Planck-scale Lorentz Violation in QED from the Crab Nebula,"We set constraints on O(E/M) Lorentz Violation in QED in an effective field
theory framework. A major consequence of such assumptions is the modification
of the dispersion relations for electrons/positrons and photons, which in turn
can affect the electromagnetic output of astrophysical objects. We compare the
information provided by multiwavelength observations with a full and
self-consistent computation of the broad-band spectrum of the Crab Nebula. We
cast constraints of order 10^{-5} at 95% confidence level on the lepton Lorentz
Violation parameters.",0707.2673v2
2007-07-31,Influence of Lorentz-violating terms on a two-level system,"The influence of Lorentz- and CPT-violating terms of the extended Standard
Model on a semi-classical two-level system is analyzed. It is shown that the
Lorentz-violating background (when coupled with the fermion sector in a vector
way) is able to induce modifications on the Rabi oscillation pattern, promoting
sensitive modulations on the usual oscillations. As for the term involving the
coefficient coupled in an axial vector way, it brings about oscillations both
on energy states and on the spin states (implied by the background). It is also
seen that such backgrounds are able to yield state oscillations even in the
absence of the electromagnetic field. The foreseen effects are used to
establish upper bounds on the Lorentz-violating coefficients.",0707.4660v2
2007-08-02,"Perfect Structure of the Special Relativity, Superluminal, Neutrino-Photon Mass and New Entangled Interaction","First, some superluminal phenomena and experiments are introduced briefly.
Next, based on the basic principles of the special relativity, the Lorentz
transformation (LT) with smaller velocity and the general Lorentz
transformation (GLT) with larger velocity should be derived simultaneously by
the classification of the timelike and the spacelike intervals. In deriving LT,
an additional independent hypothesis has been used, thus the values of velocity
are restricted absolutely, and the spacelike interval is excluded. LT and GLT
are connected by the de Broglie relation. The fundamental properties of any
four-vector and the strange characteristic which these tachyons should possess
are described. The various superluminal transformations are discussed. Further,
we think that LT is unsuitable for photon and neutrino, the photon
transformation (PT) is unified for space and time. It may reasonably overcome
some existing difficulties, and cannot restrict that the rest mass of photon
and neutrino must be zero. LT, GLT and PT together form a complete structure of
the Lorentz group. Finally, we discuss that new experiments on the quantum
entangled state shown some characters, for example, coherency, nonlocality,
quantum teleportation and superluminal. Further, it should be a new fifth
interaction, and may probably apply GLT.",0708.0435v2
2007-08-13,Lorentz Violation for Photons and Ultra-High Energy Cosmic Rays,"Lorentz symmetry breaking at very high energies may lead to photon dispersion
relations of the form omega^2=k^2+xi_n k^2(k/M_Pl)^n with new terms suppressed
by a power n of the Planck mass M_Pl. We show that first and second order terms
of size xi_1 > 10^(-14) and xi_2 < -10^(-6), respectively, would lead to a
photon component in cosmic rays above 10^(19) eV that should already have been
detected, if corresponding terms for electrons and positrons are significantly
smaller. This suggests that Lorentz invariance breakings suppressed up to
second order in the Planck scale are unlikely to be phenomenologically viable
for photons.",0708.1737v2
2007-09-18,Dynamical Lorentz and CPT symmetry breaking in a 4D four-fermion model,"In a 4D chiral Thirring model we analyse the possibility that radiative
corrections may produce spontaneous breaking of Lorentz and CPT symmetry. By
studying the effective potential, we verified that the chiral current
$\bar\psi\gamma^{\mu} \gamma_5 \psi$ may assume a nonzero vacuum expectation
value which triggers the Lorentz and CPT violations. Furthermore, by making
fluctuations on the minimum of the potential we dynamically induce a bumblebee
like model containing a Chern-Simons term.",0709.2904v2
2007-09-27,Finite Duration and Energy Effects in Lorentz-Violating Vacuum Cerenkov Radiation,"Vacuum Cerenkov radiation is possible in certain Lorentz-violating quantum
field theories, when very energetic charges move faster than the phase speed of
light. In the presence of a CPT-even, Lorentz-violating modification of the
photon sector, the character of the Cerenkov process is controlled by the
high-frequency behavior of the radiation spectrum. The development of the
Cerenkov process can be markedly different, depending on whether the only
limits on the emission of very energetic photons come from energy-momentum
conservation or whether there are additional effects that cut off the spectrum
at high frequencies. Moreover, since the high-frequency cutoff determines the
total rate at which an emitting charge loses energy, it also controls all
aspects of the emission that are related to the process's finite duration.",0709.4478v1
2007-09-28,Search for Lorentz and CPT Violation Effects in Muon Spin Precession,"The spin precession frequency of muons stored in the $(g-2)$ storage ring has
been analyzed for evidence of Lorentz and CPT violation. Two Lorentz and CPT
violation signatures were searched for: a nonzero $\Delta\omega_{a}$
(=$\omega_{a}^{\mu^{+}}-\omega_{a}^{\mu^{-}}$); and a sidereal variation of
$\omega_{a}^{\mu^{\pm}}$. No significant effect is found, and the following
limits on the standard-model extension parameters are obtained: $b_{Z} =-(1.0
\pm 1.1)\times 10^{-23}$ GeV; $(m_{\mu}d_{Z0}+H_{XY}) = (1.8 \pm 6.0 \times
10^{-23})$ GeV; and the 95% confidence level limits
$\check{b}_{\perp}^{\mu^{+}}< 1.4 \times 10^{-24}$ GeV and
$\check{b}_{\perp}^{\mu^{-}} < 2.6 \times 10^{-24}$ GeV.",0709.4670v3
2007-11-17,Search for CPT and Lorentz Violation in B0-B0bar Oscillations with Dilepton Events,"We report results of a search for CPT and Lorentz violation in B0-B0bar
oscillations using inclusive dilepton events from 232 million Y(4S) --> BBbar
decays recorded by the BABAR detector at the PEP-II B Factory at SLAC. We find
2.8sigma significance, compatible with no signal, for variations in the complex
CPT violation parameter z at the Earth's sidereal frequency and extract values
for the quantities \Delta(a_\mu) in the general Lorentz-violating
standard-model extension. The spectral powers for variations in z over the
frequency range 0.26/year to 2.1/day are also compatible with no signal.",0711.2713v1
2007-12-29,Einstein-Cartan formulation of Chern-Simons Lorentz-violating Gravity,"We consider a modification of the standard Einstein theory in four
dimensions, alternative to R. Jackiw and S.-Y. Pi, Phys. Rev. D 68, 104012
(2003), since it is based on the first-order (Einstein-Cartan) approach to
General Relativity, whose gauge structure is manifest. This is done by
introducing an additional topological term in the action which becomes a
Lorentz-violating term by virtue of the dependence of the coupling on the
space-time point. We obtain a condition on the solutions of the Einstein
equations, such that they persist in the deformed theory, and show that the
solutions remarkably correspond to the classical solutions of a collection of
independent 2+1-d (topological) Chern-Simons gravities. Finally, we study the
relation with the standard second-order approach and argue that they both
coincide to leading order in the modulus of the Lorentz-violating vector field.",0801.0067v4
2008-02-18,Lorentz symmetry violation and the results of the AUGER experiment,"We briefly discuss the implications of recent AUGER results for patterns of
Lorentz symmetry violation (LSV), assuming that the existence of the
Greisen-Zatsepin-Kuzmin cutoff is definitely confirmed. The mass composition of
the highest-energy cosmic-ray spectrum is a crucial issue. In any case, the new
data allow in principle to exclude a significant range of LSV models but leave
open several important possibilities : a weaker Lorentz breaking, a fundamental
scale beyond the Planck scale, scenarios with threshold effects... It may even
happen that spontaneous decays due to LSV fake the GZK cutoff. Space
experiments appear to be needed to further test special relativity. We also
comment on the consequences of AUGER data for superbradyons. If such particles
are present in the Universe, they may provide new forms of dark matter and dark
energy.",0802.2536v3
2008-02-25,Composite self-similar solutions for relativistic shocks: the transition to cold fluid temperatures,"The flow resulting from a strong ultrarelativistic shock moving through a
stellar envelope with a polytrope-like density profile has been studied
analytically and numerically at early times while the fluid temperature is
relativistic--that is, just before and just after the shock breaks out of the
star. Such a flow should expand and accelerate as its internal energy is
converted to bulk kinetic energy; at late enough times, the assumption of
relativistic temperatures becomes invalid. Here we present a new self-similar
solution for the post-breakout flow when the accelerating fluid has bulk
kinetic Lorentz factors much larger than unity but is cooling through $p/n$ of
order unity to subrelativistic temperatures. This solution gives a relation
between a fluid element's terminal Lorentz factor and that element's Lorentz
factor just after it is shocked. Our numerical integrations agree well with the
solution. While our solution assumes a planar flow, we show that corrections
due to spherical geometry are important only for extremely fast ejecta
originating in a region very close to the stellar surface. This region grows if
the shock becomes relativistic deeper in the star.",0802.3583v1
2008-03-18,Observational Effects of Anomalous Boundary Layers in Relativistic Jets,"Recent theoretical work has pointed out that the transition layer between a
jet an the medium surrounding it may be more complex than previously thought.
Under physically realizable conditions, the transverse profile of the Lorentz
factor in the boundary layer can be non-monotonic, displaying the absolute
maximum where the flow is faster than at the jet spine, followed by an steep
fall off. Likewise, the rest-mass density, reaches an absolute minimum
(coincident with the maximum in Lorentz factor) and then grows until it reaches
the external medium value. Such a behavior is in contrast to the standard
monotonic decline of the Lorentz factor (from a maximum value at the jet
central spine) and the corresponding increase of the rest-mass density (from
the minimum reached at the jet core). We study the emission properties of the
aforementioned anomalous shear layer structures in kiloparsec-scale jets aiming
to show observable differences with respect to conventional monotonic and
smooth boundary layers.",0803.2693v1
2008-03-23,On a New Alternative Mathematical Model for Special Relativity,"In this paper, it is shown why Lorentz Transformation implies the general
case where observed events are not necessarily in the inertia frame of any
observer but assumes a special scenario when determining the length contraction
and time dilation factors. It is shown that this limitation has led to
mathematical and physical inconsistencies. The paper explains the conditions
for a successful theory of time dilation and length contraction, and provides a
simple proof to a new generalized transformation of coordinate systems as the
only possible solution that meets those conditions. It discusses
inconsistencies of Lorentz Transformation, and shows how the new generalized
transformation resolves those apparent inconsistencies. The new transformation
agrees with Special Relativity on its conclusions of time dilation and space
contraction, and yields the same law of addition of velocities as proposed in
Lorentz Transformation.",0803.3333v2
2008-04-17,Black Hole Thermodynamics and Lorentz Symmetry,"Recent developments point to a breakdown in the generalized second law of
thermodynamics for theories with Lorentz symmetry violation. It appears
possible to construct a perpetual motion machine of the second kind in such
theories, using a black hole to catalyze the conversion of heat to work. Here
we describe and extend the arguments leading to that conclusion. We suggest the
inference that local Lorentz symmetry may be an emergent property of the
macroscopic world with origins in a microscopic second law of causal horizon
thermodynamics.",0804.2720v2
2008-04-30,Radius Destabilization in Five Dimensional Orbifolds Due to an Enhanced Casimir Effect,"One of the challenges in connecting higher dimensional theories to cosmology
is stabilization of the moduli fields. We investigate the role of a Lorentz
violating vector field in the context of stabilization. Specifically, we
compute the one loop Casimir energy in Randall-Sundrum 5-dimensional
(non-supersymmetric) S^1/ Z_2 orbifolds resulting from the interaction of a
real scalar field with periodic boundary conditions with a Lorentz violating
vector field. We find that the result is an enhanced attractive Casimir force.
Hence, for stability, positive contributions to the Casimir force from branes
and additional fields would be required to counter the destabilizing,
attractive effect of Lorentz violating fields.",0805.0019v2
2008-05-06,Limits on Neutron Lorentz Violation from the Stability of Primary Cosmic Ray Protons,"Recent evidence appears to confirm that the ultra-high-energy primary cosmic
ray spectrum consists mostly of protons. The fact that these protons can
traverse large distances to reach Earth allows us to place bounds on Lorentz
violations. The protons neither emit vacuum Cerenkov radiation nor
$\beta$-decay into neutrons, and this constrains six previously unmeasured
coefficients in the neutron sector at the 5 x 10^(-14) level. Among the
coefficients bounded here for the first time are those that control
spin-independent boost anisotropy for neutrons. This is a phenomenon which
could have existed (in light of the preexisting bounds) without additional fine
tuning. There are also similar bounds for others species of hadrons. The bounds
on Lorentz violation for neutral pions are particularly strong, at the 4 x
10^(-21) level, eleven orders of magnitude better than previous constraints.",0805.0781v2
2008-05-14,Comparison of Quantum and Classical Local-field Effects on Two-Level Atoms in a Dielectric,"The macroscopic quantum theory of the electromagnetic field in a dielectric
medium interacting with a dense collection of embedded two-level atoms fails to
reproduce a result that is obtained from an application of the classical
Lorentz local-field condition. Specifically, macroscopic quantum
electrodynamics predicts that the Lorentz redshift of the resonance frequency
of the atoms will be enhanced by a factor of the refractive index n of the host
medium. However, an enhancement factor of (n*n+2)/3 is derived using the
Bloembergen procedure in which the classical Lorentz local-field condition is
applied to the optical Bloch equations. Both derivations are short and
uncomplicated and are based on well-established physical theories, yet lead to
contradictory results. Microscopic quantum electrodynamics confirms the
classical local-field-based results. Then the application of macroscopic
quantum electrodynamic theory to embedded atoms is proved false by a specific
example in which both the correspondence principle and microscopic theory of
quantum electrodynamics are violated.",0805.2134v3
2008-06-04,Note: Axiomatic Derivation of the Doppler Factor and Related Relativistic Laws,"The formula for the relativistic Doppler effect is investigated in the
context of two compelling invariance axioms. The axioms are expressed in terms
of an abstract operation generalizing the relativistic addition of velocities.
We prove the following results. (1) If the standard representation for the
operation is not assumed a priori, then each of the two axioms is consistent
with both the relativistic Doppler effect formula and the Lorentz-Fitzgerald
Contraction. (2) If the standard representation for the operation is assumed,
then the two axioms are equivalent to each other and to the relativistic
Doppler effect formula. Thus, the axioms are inconsistent with the
Lorentz-FitzGerald Contraction in this case. (3) If the Lorentz-FitzGerald
Contraction is assumed, then the two axioms are equivalent to each other and to
a different mathematical representation for the operation which applies in the
case of perpendicular motions. The relativistic Doppler effect is derived up to
one positive exponent parameter (replacing the square root). We prove these
facts under regularity and other reasonable background conditions.",0806.0831v2
2008-06-30,Testing Lorentz Invariance and CPT Conservation with NuMI Neutrinos in the MINOS Near Detector,"A search for a sidereal modulation in the MINOS near detector neutrino data
was performed. If present, this signature could be a consequence of Lorentz and
CPT violation as predicted by a class of extensions to the Standard Model. No
evidence for a sidereal signal in the data set was found, implying that there
is no significant change in neutrino propagation that depends on the direction
of the neutrino beam in a sun-centered inertial frame. Upper limits on the
magnitudes of the Lorentz and CPT violating terms in these extensions to the
Standard Model lie between 0.01-1% of the maximum expected, assuming a
suppression of these signatures by factor of $10^{-17}$. \",0806.4945v1
2008-08-07,Is Detection of Fitzgerald-Lorentz Contraction Possible?,"Visual perception of Fitzgerald-Lorentz contraction is known to be
theoretically impossible, and this can be demonstrated pedagogically with the
aid of simple spacetime diagrams of one spatial dimension. Such diagrams also
demonstrate, simply and directly, that the apparent length of a moving meter
stick changes as it passes by and can even look elongated. In addition,
measurement of a moving meter stick with instruments, as opposed to visual
perception, must be inherently ambiguous, as the length measured depends on
clock synchronization, which is widely considered to be conventional. In fact,
for some synchronization choices, a moving meter stick would be measured as
greater than one meter. Thus, the well known Fitzgerald-Lorentz contraction
factor $\sqrt {1-v^2/c^2} $ would generally not be seen visually, and would
only be measured in a system employing one particular (Einstein)
synchronization convention.",0808.1117v1
2008-08-26,Weighted power counting and Lorentz violating gauge theories. I: General properties,"We construct local, unitary gauge theories that violate Lorentz symmetry
explicitly at high energies and are renormalizable by weighted power counting.
They contain higher space derivatives, which improve the behavior of
propagators at large momenta, but no higher time derivatives. We show that the
regularity of the gauge-field propagator privileges a particular spacetime
breaking, the one into into space and time. We then concentrate on the simplest
class of models, study four dimensional examples and discuss a number of issues
that arise in our approach, such as the low-energy recovery of Lorentz
invariance.",0808.3470v2
2008-08-26,"Weighted power counting, neutrino masses and Lorentz violating extensions of the Standard Model","We study the Standard-Model extensions that have the following features: they
violate Lorentz invariance explicitly at high energies; they are unitary,
local, polynomial and renormalizable by weighted power counting; they contain
the vertex (LH)^2, which gives Majorana masses to the neutrinos after symmetry
breaking, and possibly four fermion interactions; they do not contain
right-handed neutrinos, nor other extra fields. We study the simplest CPT
invariant Standard-Model extension of this type in detail and prove the
cancellation of gauge anomalies. We investigate the low-energy recovery of
Lorentz invariance and comment on other types of extensions.",0808.3475v2
2008-09-03,Emission and absorption of photons and the black-body spectra in Lorentz-odd Electrodynamics,"We study a number of issues related to the emission and absorption radiation
by non-relativistic electrons within the framework of a Lorentz-breaking
electrodynamics in (3+1) dimensions. Our main results concern how Planck-like
spectrum law is sensitive to terms that violate Lorentz symmetry. We have
realized that Planck law acquires extra terms proportional to the violating
parameters: for the CPT-odd model, the leading extra terms appear to be linear
or quadratic in these violating parameters according to the background vector
is parallel or perpendicular to the photon wave-vector. In the CPT-even case a
linear `correction' shows up. Among other possible ways to probe for these
violations, by means of the present results, we may quote the direct
observation of the extra contributions or an unbalancing in the mean occupation
number of photon modes in a given thermal bath.",0809.0704v1
2008-09-09,An Asymptotic Preserving Scheme for the Euler equations in a strong magnetic field,"This paper is concerned with the numerical approximation of the isothermal
Euler equations for charged particles subject to the Lorentz force. When the
magnetic field is large, the so-called drift-fluid approximation is obtained.
In this limit, the parallel motion relative to the magnetic field direction
splits from perpendicular motion and is given implicitly by the constraint of
zero total force along the magnetic field lines. In this paper, we provide a
well-posed elliptic equation for the parallel velocity which in turn allows us
to construct an Asymptotic-Preserving (AP) scheme for the Euler-Lorentz system.
This scheme gives rise to both a consistent approximation of the Euler-Lorentz
model when epsilon is finite and a consistent approximation of the drift limit
when epsilon tends to 0. Above all, it does not require any constraint on the
space and time steps related to the small value of epsilon. Numerical results
are presented, which confirm the AP character of the scheme and its Asymptotic
Stability.",0809.1527v1
2008-09-19,Limits on isotropic Lorentz violation in QED from collider physics,"We consider the possibility that Lorentz violation can generate differences
between the limiting velocities of light and charged matter. Such effects would
lead to efficient vacuum Cherenkov radiation or rapid photon decay. The absence
of such effects for 104.5 GeV electrons at the Large Electron Positron collider
and for 300 GeV photons at the Tevatron therefore constrains this type of
Lorentz breakdown. Within the context of the standard-model extension, these
ideas imply an experimental bound at the level of -5.8 x 10^{-12} <=
\tilde{\kappa}_{tr}-(4/3)c_e^{00} <= 1.2 x 10^{-11} tightening existing
laboratory measurements by 3-4 orders of magnitude. Prospects for further
improvements with terrestrial and astrophysical methods are discussed.",0809.3442v2
2008-10-10,"Unitarity, Lorentz invariance and causality in Lee-Wick theories: An asymptotically safe completion of QED","We revisit the previously unsolved problems of ensuring Lorentz invariance
and non-perturbative unitarity in Lee-Wick theories. We base our discussion on
an ultraviolet completion of QED by Lee-Wick ghost fields, which is argued to
be asymptotically safe. We argue that as long as the state space is based upon
a suitable choice of distributions of a type invented by Gel'fand and Shilov,
the Lee-Wick ghosts can be eliminated while preserving Lorentz invariance to
produce a unitary theory. The method for eliminating ghosts is in principle
non-perturbatively well-defined, in contrast with some previous proposals. We
also point out a second, independent mechanism for producing a unitary theory,
based on a covariant constraint on the maximum four-momentum, which would imply
an amusing connection, based on naturalness, between the coupling constant and
the hierarchy of scales in the theory. We further emphasize that the resulting
theory is causal, and point out some analogies between between the behaviour of
Lee-Wick ghost degrees of freedom and black holes.",0810.1928v1
2008-11-30,Testing Lorentz Invariance with Ultra High Energy Cosmic Ray Spectrum,"The GZK cutoff predicted at the Ultra High Energy Cosmic Ray (UHECR) spectrum
as been observed by the HiRes and Auger experiments. The results put severe
constraints on the effect of Lorentz Invariance Violation(LIV) which has been
introduced to explain the absence of GZK cutoff indicated in the AGASA data.
Assuming homogeneous source distribution with a single power law spectrum, we
calculate the spectrum of UHECRs observed on Earth by taking the processes of
photopion production, $e^+e^-$ pair production and adiabatic energy loss into
account. The effect of LIV is also taken into account in the calculation. By
fitting the HiRes monocular spectra and the Auger combined spectra, we show
that the LIV parameter is constrained to $\xi=-0.8^{+3.2}_{-0.5}\times10^{-23}$
and $0.0^{+1.0}_{-0.4}\times10^{-23}$ respectively, which is well consistent
with strict Lorentz Invariance up to the highest energy.",0812.0121v2
2008-12-02,On some consequences of the Snyder-Sidharth deformation of Special Relativity,"The hypothesis on a minimal scale existence in the Universe leads to
noncommutative geometry of Spacetime and thence to a modification of the
Special Relativity constraint. Sidharth has deduced that this is equivalent to
the Lorentz symmetry violation. This latter consideration was also used by
Glashow, Coleman and other scholars though based on purely phenomenological
models that have been suggested by the observation of Ultra High Energy Cosmic
Rays and Gamma Bursts. On the other hand a parallel development has been the
proposal of a small but nonzero photon mass $m_\gamma>0$ by some authors
including Sidharth, such a mass being within experimentally allowable limits.
This too leads to a small violation of the Lorentz symmetry observable in
principle in very high energy gamma rays, as in fact is claimed. In this paper
we study the Snyder--Sidharth Hamiltonian and briefly comment the
Dirac--Sidharth Hamiltonian, that is a possible explanation for observable
violation of the Lorentz symmetry.",0812.0551v2
2008-12-18,Shear Flows Driven by the Lorentz Force: An Energy Source for Coronal Mass Ejections and Flares,"Shear flows have been prescribed in numerical models of coronal mass
ejections and flares for decades as a way of energizing magnetic fields to
erupt. While such shear flows have long been observed in the solar atmosphere,
until recently, there was no compelling physical explanation for them. This
paper will discuss the discovery that such shear flows are readily explained as
a response to the Lorentz force that naturally occurs as bipolar magnetic
fields emerge and expand in a gravitationally stratified atmosphere. It will be
shown that shearing motions transport axial flux, and magnetic energy from the
submerged portion of the field to the expanding portion, strongly coupling the
solar interior to the corona. This physical process explains active region
shear flows and why the magnetic field is found to be nearly parallel to
photospheric polarity inversion lines where prominences form. Finally, shear
flows driven by the Lorentz force are shown to produce a loss of equilibrium
and eruption in magnetic arcades and flux ropes offering a convincing
explanation for CMEs and flares.",0812.3589v1
2009-01-06,Gravity from spontaneous Lorentz violation,"We investigate a class of theories involving a symmetric two-tensor field in
Minkowski spacetime with a potential triggering spontaneous violation of
Lorentz symmetry. The resulting massless Nambu-Goldstone modes are shown to
obey the linearized Einstein equations in a fixed gauge. Imposing
self-consistent coupling to the energy-momentum tensor constrains the potential
for the Lorentz violation. The nonlinear theory generated from the
self-consistent bootstrap is an alternative theory of gravity, containing
kinetic and potential terms along with a matter coupling. At energies small
compared to the Planck scale, the theory contains general relativity, with the
Riemann-spacetime metric constructed as a combination of the two-tensor field
and the Minkowski metric. At high energies, the structure of the theory is
qualitatively different from general relativity. Observable effects can arise
in suitable gravitational experiments.",0901.0662v1
2009-01-14,Fast TeV variability in blazars: jets in a jet,"The fast TeV variability of the blazars Mrk 501 and PKS 2155--304 implies a
compact emitting region that moves with a bulk Lorentz factor of Gamma_{em}~100
toward the observer. The Lorentz factor is clearly in excess of the jet Lorentz
factors Gamma_j\simless 10 measured on sub-pc scales in these sources. We
propose that the TeV emission originates from compact emitting regions that
move relativistically {\it within} a jet of bulk Gamma_j~10. This can be
physically realized in a Poynting flux-dominated jet. We show that if a large
fraction of the luminosity of the jet is prone to magnetic dissipation through
reconnection, then material outflowing from the reconnection regions can
efficiently power the observed TeV flares through synchrotron-self-Compton
emission. The model predicts simultaneous far UV/soft X-ray flares.",0901.1877v2
2009-01-27,Spectra of Field Fluctuations in Braneworld Models with Broken Bulk Lorentz Invariance,"We investigate five-dimensional braneworld setups with broken Lorentz
invariance continuing the developments of our previous paper (arXiv:0712.1136),
where a family of static self-tuning braneworld solutions was found. We show
that several known braneworld models can be embedded into this family. Then we
give a qualitative analysis of spectra of field fluctuations in backgrounds
with broken Lorentz invariance. We also elaborate on one particular model and
study spectra of scalar and spinor fields in it. It turns out that the spectra
we have found possess very peculiar and unexpected properties.",0901.4347v3
2009-01-31,Hall Coefficient of Equilibrium Supercurrents Flowing inside Superconductors,"We study augmented quasiclassical equations of superconductivity with the
Lorentz force, which is missing from the standard Ginzburg-Landau and
Eilenberger equations. It is shown that the magnetic Lorentz force on
equilibrium supercurrents induces finite charge distribution and the resulting
electric field to balance the Lorentz force. An analytic expression is obtained
for the corresponding Hall coefficient of clean type-II superconductors with
simultaneously incorporating the Fermi-surface and gap anisotropies. It has the
same sign and magnitude at zero temperature as the normal state for an
arbitrary pairing, having no temperature dependence specifically for the s-wave
pairing. The gap anisotropy may bring a considerable temperature dependence in
the Hall coefficient and can lead to its sign change as a function of
temperature, as exemplified for a model d-wave pairing with a two-dimensional
Fermi surface. The sign change may be observed in some high-$T_{c}$
superconductors.",0902.0042v1
2009-02-05,AUGER-HiRes results and models of Lorentz symmetry violation,"The implications of AUGER and HiRes results for patterns of Lorentz symmetry
violation (LSV) are examined, focusing on weak doubly special relativity
(WDSR). If the Greisen-Zatsepin-Kuzmin (GZK) cutoff is definitely confirmed,
the mass composition of the highest-energy cosmic-ray spectrum will be a
crucial issue to draw precise theoretical consequences from the experimental
results. Assuming that the observed flux suppression is due to the GZK
mechanism, data will allow in principle to exclude a significant range of LSV
models and parameters, but other important possibilities are expected to remain
open : Lorentz breaking can be weaker or occur at a scale higher than the
Planck scale, unconventional LSV effects can fake the GZK cutoff, threshold
phenomena can delay its appearance... Space experiments appear to be needed to
further test special relativity. We also examine the consequences of AUGER and
HiRes data for superbradyons. If such superluminal ultimate constituents of
matter exist in our Universe, they may provide new forms of dark matter and
dark energy.",0902.0994v1
2009-02-17,Hardy's Setup and Elements of Reality,"Several arguments have been proposed some years ago, attempting to prove the
impossibility of defining Lorentz-invariant elements of reality. Here I revisit
that question, and bring a number of additional considerations to it. I will
first analyze Hardy's argument, which was meant to show that Lorentz-invariant
elements of reality are indeed inconsistent with quantum mechanics. I will then
investigate to what extent the light cone associated with an event can be used
to define Lorentz-invariant elements of reality. It turns out to be possible,
but elements of reality associated with a product of two commuting operators
will not always be equal to the product of elements of reality associated with
each operator. I will finally examine a number of ways in which the paradoxical
features of Hardy's experiment can be better understood.",0902.3376v2
2009-03-29,Exploration of Possible Quantum Gravity Effects with Neutrinos II: Lorentz Violation in Neutrino Propagation,"It has been suggested that the interactions of energetic particles with the
foamy structure of space-time thought to be generated by quantum-gravitational
(QG) effects might violate Lorentz invariance, so that they do not propagate at
a universal speed of light. We consider the limits that may be set on a linear
or quadratic violation of Lorentz invariance in the propagation of energetic
neutrinos, v/c=[1 +- (E/M_\nuQG1)] or [1 +- (E/M_\nu QG2}^2], using data from
supernova explosions and the OPERA long-baseline neutrino experiment.",0903.5048v1
2009-03-30,Graviton Excitations and Lorentz-Violating Gravity with Cosmological Constant,"Motivated by the interest raised by the problem of Lorenz-symmetry violating
gauge theories in connetion with gravity models, this contribution sets out to
provide a general method to systematically study the excitation spectrum of
gravity actions which include a Lorentz-symmetry breaking Chern-Simons-type
action term for the spin connection. A complete set of spin-type operators is
found which accounts for the (Lorentz) violation parameter to all orders and
graviton propagators are worked out in a number of different situations.",0903.5207v2
2009-03-30,Impact of Lorentz violation on the dynamics of inflation,"This work deals with the dynamics of inflation in the context of a
scalar-vector-tensor theory of gravity exhibiting spontaneous Lorentz violation
at early times. We describe a first-order formalism which we use to obtain new
exact Lorentz violating inflationary solutions for a broad family of models,
some in the absence of a potential for the inflaton field. Our results show
that different conditions are required to solve the horizon and flatness
problems. In particular, we find a necessary condition for inflation to provide
a solution to both problems and we show that in inflationary models with no
inflaton potential a period of superinflation might be necessary to solve the
flatness problem.",0903.5297v1
2009-04-03,Comments on Holography with Broken Lorentz Invariance,"Recently a family of solutions of Einstein equations in backgrounds with
broken Lorentz invariance was found ArXiv:0712.1136. We show that the
gravitational solution recently obtained by Kachru, Liu and Mulligan in
ArXiv:0808.1725 is a part of the former solution which was derived earlier in
the framework of extra dimensional theories. We show how the energy-momentum
and Einstein tensors are related and establish a correspondence between
parameters which govern Lorentz invariance violation. Then we demonstrate that
scaling behavior of two point correlation functions of local operators in
scalar field theory is reproduced correctly for two cases with critical values
of scaling parameters. Therefore, we complete the dictionary of ""tree-level""
duality for all known solutions of the bulk theory. In the end we speculate on
relations between RG flow of a boundary theory and asymptotic behavior of
gravitational solutions in the bulk.",0904.0509v3
2009-04-07,"Spontaneous Lorentz Violation, Negative Energy and the Second Law of Thermodynamics","We reconsider the possibility of violating the generalized second law of
thermodynamics in theories with spontaneous Lorentz violation. It has been
proposed that this may be accomplished in particular with a black hole immersed
in a ghost condensate background, which may be taken to break Lorentz
invariance without appreciably distorting the space-time geometry. In this
paper we show that there in fact exist solutions explicitly describing flow of
negative energy into these black holes, allowing for violation of the second
law in a very simple way. This second law violation is independent of any
additional assumptions such as couplings of the ghost condensate to secondary
fields, and suggests that violation of the null energy condition may be the
true source of pathology in these theories.",0904.1212v2
2009-04-28,Alternative quantization of the Hamiltonian in loop quantum cosmology II: Including the Lorentz term,"Since there are quantization ambiguities in constructing the Hamiltonian
constraint operator in isotropic loop quantum cosmology, it is crucial to check
whether the key features of loop quantum cosmology are robust against the
ambiguities. In this paper, we quantize the Lorentz term of the gravitational
Hamiltonian constraint in the spatially flat FRW model by two approaches
different from that of the Euclidean term. One of the approaches is very
similar to the treatment of the Lorentz part of Hamiltonian in loop quantum
gravity and hence inherits more features from the full theory. Two symmetric
Hamiltonian constraint operators are constructed respectively in the improved
scheme. Both of them are shown to have the correct classical limit by the
semiclassical analysis. In the loop quantum cosmological model with a massless
scalar field, the effective Hamiltonians and Friedmann equations are derived.
It turns out that the classical big bang is again replaced by a quantum bounce
in both cases. Moreover, there are still great possibilities for the expanding
universe to recollapse due to the quantum gravity effect.",0904.4379v1
2009-05-11,Lorentz Violation of Quantum Gravity,"A quantum gravity theory which becomes renormalizable at short distances due
to a spontaneous symmetry breaking of Lorentz invariance and diffeomorphism
invariance is studied. A breaking of Lorentz invariance with the breaking
patterns $SO(3,1)\to O(3)$ and $SO(3,1)\to O(2)$, describing 3+1 and 2+1
quantum gravity, respectively, is proposed. A complex time dependent
Schr\""odinger equation (generalized Wheeler-DeWitt equation) for the wave
function of the universe exists in the spontaneously broken symmetry phase at
Planck energy and in the early universe, uniting quantum mechanics and general
relativity. An explanation of the second law of thermodynamics and the
spontaneous creation of matter in the early universe can be obtained in the
symmetry broken phase of gravity.",0905.1668v4
2009-06-11,Bayesian inference of jet bulk-flow speeds in FRII radio sources,"Radio jet and core data for a complete sample of 98 FRII sources with z < 1
are analysed with a Markov-Chain Monte Carlo (MCMC) model fitting method to
obtain constraints on bulk-flow speeds in the beam. The Bayesian
parameter-inference method is described and demonstrated to be capable of
providing meaningful constraints on the Lorentz factor at both kiloparsec and
parsec scales. For both jets and cores we show that models in which some
intrinsic dispersion is present in the features' intrinsic prominence,
bulk-flow speeds or both provide the best fit to the data. The constraints on
the Lorentz factor on parsec scales are found to be consistent with the
expected values given VLBI observations and other evidence, with mean gamma ~
10-14. On kiloparsec scales, the Lorentz factor is found to be ~ 1.18 - 1.49,
in agreement with the results of previous analyses of radio jet data. These
values are clearly not consistent with the gamma ~ 10 speeds required by beamed
inverse-Compton models of X-ray emission from quasar jets; our results
therefore support models that require velocity structure in powerful jets.",0906.2088v1
2009-06-13,Lorentz group theory and polarization of the light,"Some facts of the theory of the Lorentz group are specified for looking at
the problems of light polarization optics in the frames of vector
Stokes-Mueller and spinor Jones formalism. In view of great differences between
properties of isotropic and time-like vectors in Special Relativity we should
expect principal differences in describing completely polarized and partly
polarized light. In particular, substantial differences are revealed when
turning to spinor techniques in the context of the polarized light. Because
Jones complex formalism has close relation to spinor objects of the Lorentz
group, within the field of the light polarization we could have physical
realizations on the optical desk of some subtle topological distinctions
between orthogonal L_{+}^{\uparrow} =SO_{0}(3.1) and spinor SL(2.C) groups.
These topological differences of the groups find their corollaries in the
problem of the so-called spinor structure of physical space-time, some new
points are considered.",0906.2482v2
2009-06-17,Lorentz Transformations of the Electric and Magnetic Fields According to Minkowski,"The usual transformations (UT) of the 3-vectors E and B that are found by
Lorentz, Poincar\'{e} and independently by Einstein in 1905. are generally
considered to be the Lorentz transformations (LT) of E and B. According to the
UT E in one frame is 'seen' as E' and B' in a relatively moving frame. In
Minkowski's last paper, in 1908. in section 11.6, he defined the vectors (with
four components) of the electric $\Phi $ and magnetic $\Psi $ fields and
discovered that, e.g., $\Phi $ correctly transforms by the LT again to $\Phi
^{\prime}$. His correct LT are reinvented in, e.g., [11] ([11] Ivezi\'{c} T
2005 Found. Phys. Lett. 18 301). In this paper we show the essential similarity
and some differences between Minkowski's relations in section 11.6 and the
results obtained in [11]. The low-velocity limit of the UT and the LT is
briefly examined. A short discussion of the comparison with the Trouton-Noble
experiment is presented.",0906.3166v2
2009-06-29,Holonomy and Projective Equivalence in 4-Dimensional Lorentz Manifolds,"A study is made of 4-dimensional Lorentz manifolds which are projectively
related, that is, whose Levi-Civita connections give rise to the same
(unparameterised) geodesics. A brief review of some relevant recent work is
provided and a list of new results connecting projective relatedness and the
holonomy type of the Lorentz manifold in question is given. This necessitates a
review of the possible holonomy groups for such manifolds which, in turn,
requires a certain convenient classification of the associated curvature
tensors. These reviews are provided.",0906.5227v2
2009-06-30,The Lorentz Integral Transform and its Inversion,"The Lorentz integral transform method is briefly reviewed. The issue of the
inversion of the transform, and in particular its ill-posedness, is addressed.
It is pointed out that the mathematical term ill-posed is misleading and merely
due to a historical misconception. In this connection standard regularization
procedures for the solution of the integral transform problem are presented. In
particular a recent one is considered in detail and critical comments on it are
provided. In addition a general remark concerning the concept of the Lorentz
integral transform as a method with a controlled resolution is made.",0906.5421v2
2009-07-28,Transforming to Lorentz Gauge on de Sitter,"We demonstrate that certain gauge fixing functionals cannot be added to the
action on backgrounds such as de Sitter in which a linearization instability is
present. We also construct the field dependent gauge transformation which
carries the electromagnetic vector potential from a convenient, non-de Sitter
invariant gauge to the de Sitter invariant, Lorentz gauge. The transformed
propagator agrees with the de Sitter invariant result previously found by
solving the propagator equation in Lorentz gauge. This shows that the gauge
transformation technique will eliminate unphysical breaking of de Sitter
invariance introduced by a gauge condition. It is suggested that the same
technique can be used to finally resolve the issue of whether or not free
gravitons are de Sitter invariant.",0907.4930v1
2009-07-30,Negative and positive refraction are not Lorentz covariant,"The refraction of linearly polarized plane waves into a half-space occupied
by a material moving at constant velocity was studied by directly implementing
the Lorentz transformations of electric and magnetic fields. From the
perspective of a co-moving observer, the moving material was a spatially local,
pseudochiral omega material. Numerical studies revealed that whether or not
negative refraction occurrs in the moving material depends upon the speed of
movement as well as the angle of incidence and the polarization state of the
incident plane wave. Furthermore, the phenomenons of negative phase velocity
and counterposition in the moving material were similarly found not to be
Lorentz covariant; both phenomenons were also found to be sensitive to the
angle of incidence and the polarization state of the incident plane wave.",0907.5278v1
2009-08-13,Lorentz invariant field theory on kappa-Minkowski space,"It is by now well established that the momentum space dual to the
non-commutative $\kappa$-Minkowski space is a submanifold of de Sitter space.
It has been noticed recently that field theories built on such momentum space
suffer from a subtle form of Lorentz symmetry breaking. Namely, for any
negative energy mode the allowed range of rapidities is bounded above. In this
paper we construct a complex scalar field theory with a modified action of
Lorentz generators which avoids this problem. For such theory we derive
conserved charges corresponding to translational and U(1) symmetries. We also
discuss in some details the inner product and Hilbert space structure of the
$\kappa$-deformed complex quantum field.",0908.1974v1
2009-10-02,Conformal chiral boson models on twisted doubled tori and non-geometric string vacua,"We derive and analyze the conditions for quantum conformal and Lorentz
invariance of the duality symmetric interacting chiral boson sigma-models,
which are conjectured to describe non-geometric string theory backgrounds. The
one-loop Weyl and Lorentz anomalies are computed for the general case using the
background field method. Subsequently, our results are applied to a class of
(on-shell) Lorentz invariant chiral boson models which are based on twisted
doubled tori. Our findings are in agreement with those expected from the
effective supergravity approach, thereby firmly establishing that the chiral
boson models under consideration provide the string worldsheet description of
N=4 gauged supergravities with electric gaugings. Furthermore, they demonstrate
that twisted doubled tori are indeed the doubled internal geometries underlying
a large class of non-geometric string compactifications. For compact gaugings
the associated chiral boson models are automatically conformal, a fact that is
explained by showing that they are actually chiral WZW models in disguise.",0910.0431v2
2009-10-04,Preferred foliation effects in Quantum General Relativity,"We investigate the infrared (IR) effects of Lorentz violating terms in the
gravitational sector using functional renormalization group methods similar to
Reuter and collaborators. The model we consider consists of pure quantum
gravity coupled to a preferred foliation, described effectively via a scalar
field with non-standard dynamics. We find that vanishing Lorentz violation is a
UV attractive fixed-point of this model in the local potential approximation.
Since larger truncations may lead to differing results, we study as a first
example effects of additional matter fields on the RG running of the Lorentz
violating term and provide a general argument why they are small.",0910.0623v2
2009-10-28,Linearized Lorentz-Violating Gravity and Discriminant Locus in the Moduli Space of Mass Terms,"We analyze the pattern of normal modes in linearized Lorentz-violating
massive gravity over the 5-dimensional moduli space of mass terms. Ghost-free
theories arise at bifurcation points when the ghosts get out of the spectrum of
propagating particles due to vanishing of the coefficient in front of \omega^2
in the propagator. Similarly, the van Dam-Veltman-Zakharov (DVZ)
discontinuities in the Newton law arise at another type of bifurcations, when
the coefficient vanishes in front of \vec k^2. When the Lorentz invariance is
broken, these two kinds of bifurcations get independent and one can easily find
a ghost-free model without the DVZ discontinuity in the moduli space, at least,
in the quadratic (linearized) approximation.",0910.5245v1
2010-01-20,Lagrangian Formulations of Self-dual Gauge Theories in Diverse Dimensions,"In this work, we study Lagrangian formulations for self-dual gauge theories,
also known as chiral $n$-form gauge theories, for $n = 2p$ in $D = 4p+2$
dimensional spacetime. Motivated by a recent formulation of M5-branes derived
from the BLG model, we generalize the earlier Lagrangian formulation based on a
decomposition of spacetime into $(D-1)$ dimensions plus a special dimension, to
construct Lagrangian formulations based on a generic decomposition of spacetime
into $D'$ and $D"" = D - D'$ dimensions. Although the Lorentz symmetry is not
manifest, we prove that the action is invariant under modified Lorentz
transformations.",1001.3608v4
2010-01-28,Consistency relation for the Lorentz invariant single-field inflation,"In this paper we compute the sizes of equilateral and orthogonal shape
bispectrum for the general Lorentz invariant single-field inflation. The
stability of field theory implies a non-negative square of sound speed which
leads to a consistency relation between the sizes of orthogonal and equilateral
shape bispectrum, namely $f_{NL}^{orth.}\lesssim -0.054 f_{NL}^{equil.}$. In
particular, for the single-field Dirac-Born-Infeld (DBI) inflation, the
consistency relation becomes $f_{NL}^{orth.}\simeq 0.070
f_{NL}^{equil.}\lesssim 0$. These consistency relations are also valid in the
mixed scenario where the quantum fluctuations of some other light scalar fields
contribute to a part of total curvature perturbation on the super-horizon scale
and may generate a local form bispectrum. A distinguishing prediction of the
mixed scenario is $\tau_{NL}^{loc.}>({6\over 5}f_{NL}^{loc.})^2$. Comparing
these consistency relations to WMAP 7yr data, there is still a big room for the
Lorentz invariant inflation, but DBI inflation has been disfavored at more than
68% CL.",1001.5110v3
2010-02-05,Rotating optical cavity experiment testing Lorentz invariance at the 10^{-17} level,"We present an improved laboratory test of Lorentz invariance in
electrodynamics by testing the isotropy of the speed of light. Our measurement
compares the resonance frequencies of two orthogonal optical resonators that
are implemented in a single block of fused silica and are rotated continuously
on a precision air bearing turntable. An analysis of data recorded over the
course of one year sets a limit on an anisotropy of the speed of light of
\Delta c/c ~ 1 x 10^{-17}. This constitutes the most accurate laboratory test
of the isotropy of $c$ to date and allows to constrain parameters of a Lorentz
violating extension of the standard model of particle physics down to a level
of 10^{-17}.",1002.1284v1
2010-03-11,Lorentz Violation from the Higgs Portal,"We study bounds and signatures of models where the Higgs doublet has an
inhomo- geneous mass or vacuum expectation value, being coupled to a hidden
sector that breaks Lorentz invariance. This physics is best described by a
low-energy effective Lagrangian in which the Higgs speed-of-light is smaller
than c; such effect is naturally small because it is suppressed by four powers
of the inhomogeneity scale. The Lorentz violation in the Higgs sector is
communicated at tree level to fermions (via Yukawa interactions) and to massive
gauge bosons, although the most important effect comes from one-loop dia- grams
for photons and from two-loop diagrams for fermions. We calculate these effects
by deriving the renormalization-group equations for the speed-of-light of the
Standard Model particles. An interesting feature is that the strong coupling
dynamically makes the speed-of-light equal for all colored particles.",1003.2364v3
2010-03-29,Ultra high energy photons as probes of Lorentz symmetry violations in stringy space-time foam models,"The time delays between gamma-rays of different energies from extragalactic
sources have often been used to probe quantum gravity models in which Lorentz
symmetry is violated. It has been claimed that these time delays can be
explained by or at least put the strongest available constraints on quantum
gravity scenarios that cannot be cast within an effective field theory
framework, such as the space-time foam, D-brane model. Here we show that this
model would predict too many photons in the ultra-high energy cosmic ray flux
to be consistent with observations. The resulting constraints on the space-time
foam model are much stronger than limits from time delays and allow for Lorentz
violations effects way too small for explaining the observed time delays.",1003.5468v2
2010-03-29,"Imperfect fluids, Lorentz violations and Finsler Cosmology","We construct a cosmological toy model based on a Finslerian structure of
space-time. In particular, we are interested in a specific Finslerian Lorentz
violating theory based on a curved version of Cohen and Glashow's Very Special
Relativity. The osculation of a Finslerian manifold to a Riemannian leads to
the limit of Relativistic Cosmology, for a specified observer. A modified flat
FRW cosmology is produced. The analogue of a zero energy particle unfolds some
special properties of the dynamics. The kinematical equations of motion are
affected by local anisotropies. Seeds of Lorentz Violations may trigger density
inhomogeneities to the cosmological fluid.",1003.5640v2
2010-06-24,CPT invariance and neutrino physics,"CPT invariance in neutrino physics has attracted attention after the revival
of the hypothetical idea that neutrino and antineutrino might have nonequal
masses ($m_{\bar\nu} \neq m_{\nu}$) when realizing neutrino oscillations as a
new sensitive phenomenon to search for the violation of this fundamental
symmetry. Moreover, the profound relation between the CPT and Lorentz
symmetries turns the studies of CPT and Lorentz invariance violations into the
{\bf one two-sided} problem. We present a guide for non-experts through the
literature on neutrino physics. The basic works are reviewed thoroughly while
for the other papers only current results or discussion issues are quoted. The
review covers, mostly, oscillations of neutrinos, resonant change of their
flavors and cosmic neutrino physics to systematize possible evidences of
CPT/Lorentz violation in this sector of the Standard",1006.4989v2
2010-07-03,"Internal Space-time Symmetries according to Einstein, Wigner, Dirac, and Feynman","When Einstein formulated his special relativity in 1905, he established the
law of Lorentz transformations for point particles. It is now known that
particles have internal space-time structures. Particles, such as photons and
electrons, have spin variables. Protons and other hadrons are regarded as bound
states of more fundamental particles called quarks which have their internal
variables. It is still one of the most outstanding problems whether these
internal space-time variables are transformed according to Einstein's law of
Lorentz transformations. It is noted that Wigner, Dirac, and Feynman made
important contributions to this problem. By integrating their efforts, it is
then shown possible to construct a picture of the internal space-time symmetry
consistent with Einstein's Lorentz covariance.",1007.0517v1
2010-07-14,Induced Chern-Simons Like Action by Lorentz Symmetry Breaking in (3+1)D QED,"In this paper, the induced Chern-Simons like action for a system of fermions
interacting with a gauge field in (3 +1) dimensions is calculated in the
presence of a background field that breaks the Lorentz and CPT symmetries. The
main result of this work corresponds to the obtation of a usual
Chern-Simons-type action in four-dimensional spacetime resulting from the
addition to the conventional QED Lagrangian of a term with a background field
that breaks the Lorentz symmetry of the Lagrangian gauge theory. It is pointed
out that the proportionality constant in that term depends heavily on the
regularization method used in the computations. As the articles on this subject
in the literature are very difficult to read, here calculations are performed
clearly and objectively.",1007.2250v2
2010-08-02,Lorentz Violation by Quark Condensation,"At the TeV scale, heavy quarks, for example the 4th generation quarks of the
Standard Model with four generations, can form condensates which dynamically
break the electroweak symmetry. A dense quark system may form other types of
condensates which dynamically break the Lorentz symmetry. These condensates are
described by a Nambu-Jona-Lasinio type effective action, similar to the quark
condensation models in hadronic matter with finite density. The vacua
corresponding to these two types of condensates compete for the global minimum
of the effective potential, depending on the energy scale and the related
strong dynamics. The resultant Goldstone gauge boson may produce observable
effects in relativistic heavy-ion colliders.",1008.0364v1
2010-08-03,Test of Lorentz Symmetry by using a 3He/129Xe Co-Magnetometer,"To test Lorentz symmetry we used a 3He/129Xe co-magnetometer. We will give a
short summary of our experimental setup and the results of our latest
measurements. We obtained preliminary results for the equatorial component of
the background field interacting with the spin of the bound neutron: b_n < 3.72
x 10^(-32) GeV (95 C.L.).",1008.0579v1
2010-08-04,Spin-momentum correlation in relativistic single particle quantum states,"This paper was concerned with the spin-momentum correlation in
single-particle quantum states, which is described by the mixed states under
Lorentz transformations. For convenience, instead of using the superposition of
momenta we use only two momentum eigen states (p1 and p2) that are
perpendicular to the Lorentz boost direction. Consequently, in 2D momentum
subspace we show that the entanglement of spin-momentum in the moving frame
depends on the angle between them. Therefore, when spin and momentum are
perpendicular the measure of entanglement is not observer-dependent quantity in
inertial frame. Likewise, we have calculated the measure of entanglement (by
using the concurrence) and has shown that entanglement decreases with respect
to the increasing of observer velocity. Finally, we argue that, Wigner rotation
is induced by Lorentz transformations can be realized as controlling operator.",1008.0690v1
2010-08-06,Quaternionic Formulation of the Dirac Equation,"The Dirac equation with Lorentz violation involves additional coefficients
and yields a fourth-order polynomial that must be solved to yield the
dispersion relation. The conventional method of taking the determinant of
$4\times 4$ matrices of complex numbers often yields unwieldy dispersion
relations. By using quaternions, the Dirac equation may be reduced to $2 \times
2$ form in which the structure of the dispersion relations become more
transparent. In particular, it is found that there are two subsets of
Lorentz-violating parameter sets for which the dispersion relation is easily
solvable. Each subset contains half of the parameter space so that all
parameters are included.",1008.1280v1
2010-08-29,Finsler Branes and Quantum Gravity Phenomenology with Lorentz Symmetry Violations,"A consistent theory of quantum gravity (QG) at Planck scale almost sure
contains manifestations of Lorentz local symmetry violations (LV) which may be
detected at observable scales. This can be effectively described and classified
by models with nonlinear dispersions and related Finsler metrics and
fundamental geometric objects (nonlinear and linear connections) depending on
velocity/ momentum variables. We prove that the trapping brane mechanism
provides an accurate description of gravitational and matter field phenomena
with LV over a wide range of distance scales and recovering in a systematic way
the general relativity (GR) and local Lorentz symmetries. In contrast to the
models with extra spacetime dimensions, the Einstein-Finsler type gravity
theories are positively with nontrivial nonlinear connection structure,
nonholonomic constraints and torsion induced by generic off-diagonal
coefficients of metrics, and determined by fundamental QG and/or LV effects.",1008.4912v3
2010-09-29,Dynamical mass generation in Lorentz-violating QED,"A Lorentz violating modification of massless QED is proposed, with higher
order space derivatives for the photon field. The fermion dynamical mass
generation is studied with the Schwinger-Dyson approach, and it is found that
the resulting mass is many orders of magnitude smaller than the (Plank-) mass
scale introduced by the higher order derivative terms. This is due to a
suppressing factor, non-analytic in the fine structure constant and
exponentially small. This scenario is an alternative to the Higgs mechanism for
the electron mass, which arises here from Lorentz violating effects at high
energies.",1009.5834v4
2010-10-06,f(T) Gravity and local Lorentz invariance,"We show that in theories of generalised teleparallel gravity, whose
Lagrangians are algebraic functions of the usual teleparallel Lagrangian, the
action and the field equations are not invariant under local Lorentz
transformations. We also argue that these theories appear to have extra degrees
of freedom with respect to general relativity. The usual teleparallel
Lagrangian, which has been extensively studied and leads to a theory
dynamically equivalent to general relativity, is an exception. Both of these
facts appear to have been overlooked in the recent literature on f(T) gravity,
but are crucial for assessing the viability of these theories as alternative
explanations for the acceleration of the universe.",1010.1041v3
2010-10-26,The IR stability of de Sitter QFT: results at all orders,"We show that the Hartle-Hawking vacuum for theories of interacting massive
scalars in de Sitter space is both perturbatively well-defined and stable in
the IR. Correlation functions in this state may be computed on the Euclidean
section and Wick-rotated to Lorentz-signature. The results are manifestly de
Sitter-invariant and contain only the familiar UV singularities. More
importantly, the connected parts of all Lorentz-signature correlators decay at
large separations of their arguments. Our results apply to all cases in which
the free Euclidean vacuum is well defined, including scalars with masses
belonging to both the complementary and principal series of $SO(D,1)$. This
suggests that interacting QFTs in de Sitter -- including higher spin fields --
are perturbatively IR-stable at least when i) the Euclidean vacuum of the
zero-coupling theory exists and ii) corresponding Lorentz-signature
zero-coupling correlators decay at large separations. This work has significant
overlap with a paper by Stefan Hollands, which is being released
simultaneously.",1010.5327v2
2010-11-11,Lorentz invariant nonzero minimal uncertainty in position and inhomogeneity of space at the Planck scale,"The suspicion that the existence of a minimal uncertainty in position
measurements violates Lorentz invariance seems unfounded. It is shown that the
existence of such a nonzero minimal uncertainty in position is not only
consistent with Lorentz invariance, but that the latter also fixes the algebra
between position and momentum which gives rise to this minimal uncertainty. We
also investigate how this algebra affects the underlying quantum mechanical
structure, and why, at the Planck scale, space can no longer be considered
homogeneous.",1011.2733v8
2010-11-18,Consistency of isotropic modified Maxwell theory: Microcausality and unitarity,"The Lorentz-violating isotropic modified Maxwell theory minimally coupled to
standard Dirac theory is characterized by a single real dimensionless parameter
which is taken to vanish for the case of the standard (Lorentz-invariant)
theory. A finite domain of positive and negative values of this
Lorentz-violating parameter is determined, in which microcausality and
unitarity hold. The main focus of this article is on isotropic modified Maxwell
theory, but similar results for two anisotropic nonbirefringent cases are
presented in the appendices.",1011.4258v5
2010-11-23,Eikonal equation of the Lorentz-violating Maxwell theory,"We derive the eikonal equation of light wavefront in the presence of Lorentz
invariance violation (LIV) from the photon sector of the standard model
extension (SME). The results obtained from the equations of $\mathbf{E}$ and
$\mathbf{B}$ fields respectively are the same. This guarantees the
self-consistency of our derivation. We adopt a simple case with only one
non-zero LIV parameter as an illustration, from which we find two points. One
is that, in analogy with Hamilton-Jacobi equation, from the eikonal equation,
we can derive dispersion relations which are compatible with results obtained
from other approaches. The other is that, the wavefront velocity is the same as
the group velocity, as well as the energy flow velocity. If further we define
the signal velocity $v_s$ as the front velocity, there always exists a mode
with $v_s>1$, hence causality is violated classically. Thus our method might be
useful in the analysis of Lorentz violation in QED in terms of classical
causality .",1011.5074v1
2010-12-14,Covariant Worldline Numerics for Charge Motion with Radiation Reaction,"We develop a numerical formulation to calculate the classical motion of
charges in strong electromagnetic fields, such as those occurring in
high-intensity laser beams. By reformulating the dynamics in terms of SL(2,C)
matrices representing the Lorentz group, our formulation maintains explicit
covariance, in particular the mass-shell condition. Considering an
electromagnetic plane wave field where the analytic solution is known as a test
case, we demonstrate the effectiveness of the method for solving both the
Lorentz force and the Landau-Lifshitz equations. The latter, a second order
reduction of the Lorentz-Abraham-Dirac equation, describes radiation reaction
without the usual pathologies.",1012.3082v1
2010-12-15,QED with minimal and nonminimal couplings: on the quantum generation of Lorentz violating terms in the pure photon sector,"We consider an effective model formed by usual QED (minimal coupling) with
the addition of a nonminimal Lorentz violating interaction (proportional to a
fixed 4-vector $b_\mu$) which may radiatively generate both CPT even and odd
terms in the pure gauge sector.
  We show that gauge invariance from usual QED, considered as a limit of the
model for $b_\mu \rightarrow 0$, plays an important role in the discussion of
the radiatively induced Lorentz violating terms at one-loop order. Moreover,
despite the nonrenormalizability of the (effective) model preventing us from
readily extending our discussion to higher orders, it is still possible to
display the general form of the breaking terms of the photon sector in the on
shell limit organized in powers of $b_\mu$ which in turn can be considered as a
small expansion parameter.",1012.3291v2
2011-03-29,Status of Horava gravity: A personal perspective,"Horava gravity is a relatively recent (Jan 2009) idea in theoretical physics
for trying to develop a quantum field theory of gravity. It is not a string
theory, nor loop quantum gravity, but is instead a traditional quantum field
theory that breaks Lorentz invariance at ultra-high (presumably
trans-Planckian) energies, while retaining approximate Lorentz invariance at
low and medium (sub-Planckian) energies. The challenge is to keep the Lorentz
symmetry breaking controlled and small - small enough to be compatible with
experiment. I will give a very general overview of what is going on in this
field, paying particular attention to the disturbing role of the scalar
graviton.",1103.5587v2
2011-03-30,Numerical simulations of high Lundquist number relativistic magnetic reconnection,"We present the results of two-dimensional and three-dimensional
magnetohydrodynamical numerical simulations of relativistic magnetic
reconnection, with particular emphasis on the dynamics of the plasma in a
Petschek-type configuration with high Lundquist numbers, S\sim 10^5-10^8. The
numerical scheme adopted, allowing for unprecedented accuracy for this type of
calculations, is based on high order finite volume and discontinuous Galerkin
methods as recently proposed by \citet{Dumbser2009}. The possibility of
producing high Lorentz factors is discussed, showing that Lorentz factors close
to \sim 4 can be produced for a plasma parameter \sigma_m=20. Moreover, we find
that the Sweet-Parker layers are unstable, generating secondary magnetic
islands, but only for S > S_c = 10^8, much larger than what is reported in the
Newtonian regime. Finally, the effects of a mildly anisotropic Ohm law are
considered in a configuration with a guide magnetic field. Such effects produce
only slightly faster reconnection rates and Lorentz factors of about 1% larger
with respect to the perfectly isotropic Ohm law.",1103.5924v2
2011-04-17,Asymptotic-Preserving scheme for a bi-fluid Euler-Lorentz model,"The present work is devoted to the simulation of a strongly magnetized plasma
considered as a mixture of an ion fluid and an electron fluid. For the sake of
simplicity, we assume that the model is isothermal and described by Euler
equations coupled with a term representing the Lorentz force. Moreover we
assume that both Euler systems are coupled through a quasi-neutrality
constraint. The numerical method which is described in the present document is
based on an Asymptotic-Preserving semi-discretization in time of a variant of
this two-fluid Euler-Lorentz model with a small perturbation of the
quasi-neutrality constraint. Firstly, we present the two-fluid model and the
motivations for introducing a small perturbation into the quasi-neutrality
equation, then we describe the time semi-discretization of the perturbed model
and a fully-discrete finite volume scheme based on it. Finally, we present some
numerical results which have been obtained with this method.",1104.3339v1
2011-04-26,Change of basis and Gram-Schmidt orthonormalization in special relativity,"While an explicit basis is common in the study of Euclidean spaces, it is
usually implied in the study of inertial relativistic systems. There are some
conceptual advantages to including the basis in the study of special
relativistic systems. A Minkowski metric implies a non-orthonormal basis, and
to deal with this complexity the concepts of reciprocal basis and the vector
dual are introduced. It is shown how the reciprocal basis is related to upper
and lower index coordinate extraction, the metric tensor, change of basis,
projections in non-orthonormal bases, and finally the Gram-Schmidt procedure.
It will be shown that Lorentz transformations can be viewed as change of basis
operations. The Lorentz boost in one spatial dimension will be derived using
the Gram-Schmidt orthonormalization algorithm, and it will be shown how other
Lorentz transformations can be derived using the Gram-Schmidt procedure.",1104.4829v1
2011-05-19,Hiding Lorentz Invariance Violation with MOND,"Ho\v{r}ava gravity is a attempt to construct a renormalizable theory of
gravity by breaking the Lorentz Invariance of the gravitational action at high
energies. The underlying principle is that Lorentz Invariance is an approximate
symmetry and its violation by gravitational phenomena is somehow hidden to
present limits of observational precision. Here I point out that a simple
modification of the low energy limit of Ho\v{r}ava gravity in its
non-projectable form can effectively camouflage the presence of a preferred
frame in regions where the Newtonian gravitational field gradient is higher
than $cH_0$; this modification results in the phenomenology of MOND at lower
accelerations.",1105.3910v3
2011-05-31,Micromagnetic study of flux-closure states in Fe dots using quantitative Lorentz Microscopy,"A micromagnetic study of epitaxial micron-sized iron dots is reported through
the analysis of Fresnel contrast in Lorentz Microscopy. Their use is reviewed
and developed through analysis of various magnetic structures in such dots.
Simple Landau configuration is used to investigate various aspects of
asymmetric Bloch domain walls. The experimental width of such a complex wall is
first derived and its value is discussed with the help of micromagnetic
simulations. Combination of these two approaches enables us to define what is
really extracted when estimating asymmetric wall width in Lorentz Microscopy.
Moreover, quantitative data on the magnetization inside the dot is retrieved
using phase retrieval as well as new informations on the degrees of freedom of
such walls. Finally, it is shown how the existence and the propagation of a
surface vortex can be characterized and monitored. This demonstrates the
ability to reach a magnetic sensitivity a priori hidden in Fresnel contrast,
based on an original image treatment and backed-up by the evaluation of
contrasts obtained from micromagnetic simulations.",1105.6295v2
2011-05-31,The Cosmological Constant and Lorentz Invariance of the Vacuum State,"One hope to solve the cosmological constant problem is to identify a symmetry
principle, based on which the cosmological constant can be reduced either to
zero, or to a tiny value. Here, we note that requiring that the vacuum state is
Lorentz invariant significantly reduces the theoretical value of the vacuum
energy density. Hence, this also reduces the discrepancy between the observed
value of the cosmological constant and its theoretical expectation, down from
123 orders of magnitude to 56 orders of magnitude. We find that, at one loop
level, massless particles do not yield any contribution to the cosmological
constant. Another important consequence of Lorentz symmetry is stabilization of
the gravitational hierarchy: the cosmological constant (divided by Newton's
constant) does not run as the quartic power of the renormalization group scale,
but instead only logarithmically.",1105.6296v1
2011-06-07,Small Lorentz violations in quantum gravity: do they lead to unacceptably large effects?,"We discuss the applicability of the argument of Collins, P\'erez, Sudarsky,
Urrutia and Vucetich to loop quantum gravity. This argument suggests that
Lorentz violations, even ones that only manifest themselves at energies close
to the Planck scale, have significant observational consequences at low
energies when one considers perturbative quantum field theory and
renormalization. We show that non-perturbative treatments like those of loop
quantum gravity may generate deviations of Lorentz invariance of a different
type than those considered by Collins et al. that do not necessarily imply
observational consequences at low energy.",1106.1417v1
2011-06-17,"Lorentz violation, Two times physics and Strings","We study a recently proposed generalization of the relativistic particle by
Kosteleck\'y, that includes explicit Lorentz violation. We present an
alternative action for this system and we show that this action can be
interpreted as a particle in curved space with a metric that depends on the
Lagrange multipliers. Furthermore, the following results are established for
this model: (i) there exists a limit where this system has more local
symmetries that the usual relativistic particle; (ii) in this limit if we
restore the Lorentz symmetry we obtain a direct relationship with the two time
physics; (iii) also we show that if we intent to restore the Poincar\'e
symmetry we obtain the action of the relativistic bosonic string.",1106.3529v1
2011-06-23,Ultrarelativistic Bose-Einstein Gas on Lorentz Symmetry Violation,"In this paper we study the effects of Lorentz Symmetry Breaking on
thermodynamics properties of ideal gases. Inspired in the dispersion relation
came from the Carroll-Field-Jackiw model for Electrodynamics with Lorentz and
CPT violation term, we compute the thermodynamics quantities for a Boltzmann,
Fermi-Dirac and Bose-Einstein distributions. Two regimes are analyzed: the non-
relativistic and the relativistic one. In the first case we show that the
topological mass induced by the Chern-Simons term behaves as a chemical
potential. For the Bose-Einstein gases it could be found a condensation in both
regimes, being the appearance of a condensate in the relativistic regime, the
main contribution of this work.",1106.4604v1
2011-06-27,Lorentz-violating effects in the Bose-Einstein condensation of an ideal bosonic gas,"We have studied the effects of Lorentz-violation in the Bose-Einstein
condensation (BEC) of an ideal boson gas, by assessing both the nonrelativistic
and ultrarelativistic limits. Our model describes a massive complex scalar
field coupled to a CPT-even and Lorentz-violating background. We irst analyze
the nonrelativistic case, at this level by using experimental data, we obtain
upper-bounds for some LIV parameters. In the sequel, we have constructed the
partition function for the relativistic ideal boson gas which to be able of a
consistent description requires the imposition of severe restrictions on some
LIV coefficients. In both cases, we have demonstrated that the LIV
contributions are contained in an overall factor, which multiplies almost all
thermodynamical properties. An exception is the fraction of the condensed
particles.",1106.5534v2
2011-06-27,Isometry groups of Lorentzian manifolds of finite volume and The local geometry of compact homogeneous Lorentz spaces,"Based on the work of Adams and Stuck as well as on the work of Zeghib, we
classify the Lie groups which can act isometrically and locally effectively on
Lorentzian manifolds of finite volume. In the case that the corresponding Lie
algebra contains a direct summand isomorphic to the two-dimensional special
linear algebra or to a twisted Heisenberg algebra, we also describe the
geometric structure of the manifolds if they are compact. Using these results,
we investigate the local geometry of compact homogeneous Lorentz spaces whose
isometry groups have non-compact connected components. It turns out that they
all are reductive. We investigate the isotropy representation, curvatures and
holonomy. Especially, we obtain that any Ricci-flat compact homogeneous Lorentz
space is flat or has compact isometry group.",1106.5539v2
2011-06-29,Lorentz noninvariant oscillations of massless neutrinos are excluded,"The bicycle model of Lorentz noninvariant neutrino oscillations without
neutrino masses naturally predicts maximal mixing and a 1/E dependence of the
oscillation argument for muon-neutrino to tau-neutrino oscillations of
atmospheric and long-baseline neutrinos, but cannot also simultaneously fit the
data for solar neutrinos and KamLAND. Within the Standard Model Extension, we
examine all 19 possible structures of the effective Hamiltonian for Lorentz
noninvariant oscillations of massless neutrinos that naturally have a 1/E
dependence at high neutrino energy. Due to the lack of any evidence for
direction dependence, we consider only direction-independent oscillations.
Although we find a number of models with a 1/E dependence for atmospheric and
long-baseline neutrinos, none can also simultaneously fit solar and KamLAND
data.",1106.6023v2
2011-08-18,Massive Gravity with Anisotropic Scaling,"We study a massive gravity theory which is Lorentz violating all the way from
ultraviolet to infrared energy scales. At short distances the theory breaks
diffeomorphism invariance and time and space scale differently. Dynamical
metric fields are introduced which upon linearization over a Minkowski
background correspond to Lorentz violating mass terms at large distances. We
perform a scalar perturbation analysis and we show that with an appropriate
choice of parameters the theory is healthy without ghosts, tachyons, strong
coupling problems and instabilities",1108.3771v2
2011-09-16,Multisubband transport and magnetic deflection of Fermi electron trajectories in three terminal junctions and rings,"We study the electron transport in three terminal junctions and quantum rings
looking for the classical deflection of electron trajectories in presence of
intersubband scattering. We indicate that although the Aharonov-Bohm
oscillations and the Lorentz force effects co-exist in the low subband
transport, for higher Fermi energies a simultaneous observation of the both
effects is difficult and calls for carefully formed structures. In particular,
in quantum rings with channels wider than the input lead the Lorentz force is
well resolved but the Aharonov-Bohm periodicity is lost in chaotic scattering
events. In quantum rings with equal length of the channels and $T$-shaped
junctions the Aharonov-Bohm oscillations are distinctly periodic but the
Lorentz force effects are not well pronounced. We find that systems with the
wedge shaped junctions allow for observation of both the periodic Aharonov-Bohm
oscillations and the magnetic deflection.",1109.3589v2
2011-09-16,Spontaneous breakdown of Lorentz symmetry in scalar QED with higher order derivatives,"Scalar QED is studied with higher order derivatives for the scalar field
kinetic energy. A local potential is generated for the gauge field due to the
covariant derivatives and the vacuum with non-vanishing expectation value for
the scalar field and the vector potential is constructed in the leading order
saddle point expansion. This vacuum breaks the global gauge and Lorentz
symmetry spontaneously. The unitarity of time evolution is assured in the
physical, positive norm subspace and the linearized equations of motion are
calculated. Goldstone theorem always keeps the radiation field massless. A
particular model is constructed where the the full set of standard Maxwell
equations is recovered on the tree level thereby relegating the effects of
broken Lorentz symmetry to the level of radiative corrections.",1109.3679v1
2011-09-26,Interpreting OPERA results on superluminal neutrino,"OPERA has claimed the discovery of superluminal propagation of neutrinos. We
analyze the consistency of this claim with previous tests of special
relativity. We find that reconciling the OPERA measurement with information
from SN1987a and from neutrino oscillations requires stringent conditions. The
superluminal limit velocity of neutrinos must be nearly flavor independent,
must decrease steeply in the low-energy domain, and its energy dependence must
depart from a simple power law. We construct illustrative models that satisfy
these conditions, by introducing Lorentz violation in a sector with light
sterile neutrinos. We point out that, quite generically, electroweak quantum
corrections transfer the information of superluminal neutrino properties into
Lorentz violations in the electron and muon sector, in apparent conflict with
experimental data.",1109.5682v2
2011-09-28,On the Possibility of Superluminal Neutrino Propagation,"We analyze the possibility of superluminal neutrino propagation delta v = (v
- c)/c > 0 as indicated by OPERA data, in view of previous phenomenological
constraints from supernova SN1987a and gravitational Cerenkov radiation. We
argue that the SN1987a data rule out delta v ~ (E_\nu/M_N)^N for N \le 2 and
exclude, in particular, a Lorentz-invariant interpretation in terms of a
'conventional' tachyonic neutrino. We present two toy Lorentz-violating
theoretical models, one a Lifshitz-type fermion model with superluminality
depending quadratically on energy, and the other a Lorentz-violating
modification of a massless Abelian gauge theory with axial-vector couplings to
fermions. In the presence of an appropriate background field, fermions may
propagate superluminally or subluminally, depending inversely on energy, and on
direction. Reconciling OPERA with SN1987a would require this background field
to depend on location.",1109.6296v3
2011-10-03,OPERA neutrinos and relativity,"In a recent study, Cohen and Glashow argue that superluminal neutrinos of the
type recently reported by OPERA should be affected by anomalous Cherenkov-like
processes. This causes them to loose much of their energy before reaching the
OPERA detectors. Related concerns were reported also by Gonzalez-Mestres and Bi
et. al., who argued that pions cannot decay to superluminal neutrinos over part
of the energy range studied by OPERA. We observe here that these arguments are
set within a framework in which Lorentz symmetry is broken, by the presence of
a preferred frame. We further show that these anomalous processes are forbidden
if Lorentz symmetry is instead ""deformed"", preserving the relativity of
inertial frames. These deformations add non-linear terms to energy momentum
relations, conservation laws and Lorentz transformations in a way that is
consistent with the relativity of inertial observers.",1110.0521v4
2011-10-18,Power-Law tailed statistical distributions and Lorentz transformations,"The present Letter, deals with the statistical theory [Phys. Rev. E {\bf 66},
056125 (2002) and Phys. Rev E {\bf 72}, 036108 (2005)], which predicts the
probability distribution $p(E) \propto \exp_{\kappa} (-I)$, where, $I \propto
\beta E -\beta \mu$, is the collision invariant, and
$\exp_{\kappa}(x)=(\sqrt{1+ \kappa^2 x^2}+\kappa x)^{1/\kappa}$, with
$\kappa^2<1$. This, experimentally observed distribution, at low energies
behaves as the Maxwell-Boltzmann exponential distribution, while at high
energies presents power law tails. Here we show that the function
$\exp_{\kappa}(x)$ and its inverse $\ln_{\kappa}(x)$, can be obtained within
the one-particle relativistic dynamics, in a very simple and transparent way,
without invoking any extra principle or assumption, starting directly from the
Lorentz transformations. The achievements support the idea that the power law
tailed distributions are enforced by the Lorentz relativistic microscopic
dynamics, like in the case of the exponential distribution which follows from
the Newton classical microscopic dynamics.",1110.3944v1
2012-02-27,Extended Einstein-Cartan theory a la Diakonov: the field equations,"Diakonov formulated a model of a primordial Dirac spinor field interacting
gravitationally within the geometric framework of the Poincar\'e gauge theory
(PGT). Thus, the gravitational field variables are the orthonormal coframe
(tetrad) and the Lorentz connection. A simple gravitational gauge Lagrangian is
the Einstein-Cartan choice proportional to the curvature scalar plus a
cosmological term. In Diakonov's model the coframe is eliminated by expressing
it in terms of the primordial spinor. We derive the corresponding field
equations for the first time. We extend the Diakonov model by additionally
eliminating the Lorentz connection, but keeping local Lorentz covariance
intact. Then, if we drop the Einstein-Cartan term in the Lagrangian, a
nonlinear Heisenberg type spinor equation is recovered in the lowest
approximation.",1202.6045v1
2012-03-13,Differential algebras on kappa-Minkowski space and action of the Lorentz algebra,"We propose two families of differential algebras of classical dimension on
kappa-Minkowski space. The algebras are constructed using realizations of the
generators as formal power series in a Weyl super-algebra. We also propose a
novel realization of the Lorentz algebra so(1,n-1) in terms of Grassmann-type
variables. Using this realization we construct an action of so(1,n-1) on the
two families of algebras. Restriction of the action to kappa-Minkowski space is
covariant. In contrast to the standard approach the action is not Lorentz
covariant except on constant one-forms, but it does not require an extra
cotangent direction.",1203.2762v1
2012-03-13,"""Planck-scale physics"" of vacuum in a strong magnetic field","It is widely believed that Lorentz symmetry of physical vacuum is broken near
the Planck scale. Here we show that recently demonstrated ""hyperbolic
metamaterial"" behaviour of vacuum in a strong magnetic field provides us with
an interesting analogy of the Planck-scale physics. As demonstrated by
Chernodub, strong magnetic field forces vacuum to develop real condensates of
electrically charged \rho mesons, which form an anisotropic inhomogeneous
superconducting state similar to Abrikosov vortex lattice. As far as
electromagnetic field behaviour is concerned, this hyperbolic metamaterial
state of vacuum exhibits effective 3D Lorentz symmetry, which is broken at
small scale (large momenta) due to spatial dispersion. Thus, an effective
Lorentz symmetry-violating ""Planck scale"" may be introduced. Near the critical
magnetic field this effective ""Planck scale"" is much larger than the
metamaterial periodicity defined by the \rho meson lattice. Similar to regular
hyperbolic metamaterials, spatial dispersion of vacuum in a strong magnetic
field leads to appearance of the ""additional wave"", which manifests itself as a
""heavy"" extraordinary photon with an effective mass ~2GeV.",1203.2858v2
2012-03-27,Search for violation of Lorentz invariance in top quark pair production and decay,"Using data collected with the D0 detector at the Fermilab Tevatron Collider,
corresponding to 5.3 fb$^{-1}$ of integrated luminosity, we search for
violation of Lorentz invariance by examining the \ttbar production cross
section in lepton+jets final states. We quantify this violation using the
standard-model extension framework, which predicts a dependence of the \ttbar
production cross section on sidereal time as the orientation of the detector
changes with the rotation of the Earth. Within this framework, we measure
components of the matrices $(c_Q)_{\mu\nu 33}$ and $(c_U)_{\mu\nu 33}$
containing coefficients used to parametrize violation of Lorentz invariance in
the top quark sector. Within uncertainties, these coefficients are found to be
consistent with zero.",1203.6106v1
2012-07-03,Lorentz Symmetry in QFT on Quantum Bianchi I Space-Time,"We develop the quantum theory of a scalar field on LQC Bianchi I geometry. In
particular, we focus on single modes of the field: the evolution equation is
derived from the quantum scalar constraint, and it is shown that the same
equation can be obtained from QFT on an ""classical"" effective geometry. We
investigate the dependence of this effective space-time on the wavevector of
the mode (which could in principle generate a deformation in local
Lorentz-symmetry), focusing our attention on the dispersion relation. We prove
that when we disregard backreaction no Lorentz-violation is present, despite
the effective metric being different than the classical Bianchi I one. A
preliminary analysis of the correction due to inclusion of backreaction is
briefly discussed in the context of Born-Oppenheimer approximation.",1207.0671v3
2012-07-05,Dynamical 3-Space: neo-Lorentz Relativity,"The major extant relativity theories - Galileo's Relativity (GaR), Lorentz's
Relativity (LR) and Einstein's Special Relativity (SR), with the latter much
celebrated, while the LR is essentially ignored. Indeed it is often incorrectly
claimed that SR and LR are experimentally indistinguishable. Here we show that
(i) SR and LR are experimentally distinguishable, (ii) that comparison of
gas-mode Michelson interferometer experiments with spacecraft earth-flyby
Doppler shift data demonstrate that it is LR that is consistent with the data,
while SR is in conflict with the data, (iii) SR is exactly derivable from GaR
by means of a mere linear change of space and time coordinates that mixes the
Galilean space and time coordinates. So it is GaR and SR that are equivalent.
Hence the well-known SR relativistic effects are purely coordinate effects, and
cannot correspond to the observed relativistic effects. The connections between
these three relativity theories has become apparent following the discovery
that space is an observable dynamical textured system, and that space and time
are distinct phenomena, leading to a neo-Lorentz Relativity (nLR). The observed
relativistic effects are dynamical consequences of nLR and 3-space. In
particular a proper derivation of the Dirac equation from nLR is given, which
entails the derivation of the rest mass energy mc^2",1207.1430v1
2012-07-10,"Lorentz violation, Gravity, Dissipation and Holography","We reconsider Lorentz Violation (LV) at the fundamental level. We show that
Lorentz Violation is intimately connected with gravity and that LV couplings in
QFT must always be fields in a gravitational sector. Diffeomorphism invariance
must be intact and the LV couplings transform as tensors under coordinate/frame
changes. Therefore searching for LV is one of the most sensitive ways of
looking for new physics, either new interactions or modifications of known
ones. Energy dissipation/Cerenkov radiation is shown to be a generic feature of
LV in QFT. A general computation is done in strongly coupled theories with
gravity duals. It is shown that in scale invariant regimes, the energy
dissipation rate depends non-triviallly on two characteristic exponents, the
Lifshitz exponent and the hyperscaling violation exponent.",1207.2325v2
2012-07-19,"Comment on ""Trouble with the Lorentz Law of Force: Incompatibility with Special Relativity and Momentum Conservation""","In a recent Letter [arXiv:1205.0096], Mansuripur considers a magnetic dipole
positioned at a fixed location from a point charge. Performing a Lorentz
transformation to a laboratory frame where the charge distribution moves he
finds that `a net torque acts on the dipole pair'. He then argues that `this
torque in the (lab) frame in the absence of a corresponding torque in the
(rest) frame is sufficient proof of the inadequacy of the Lorentz (force) law'.
  In this comment we demonstrate that the presence of a torque is not
incompatible with special relativity: it is required by the conservation laws
that apply to the total momentum of the system (including the particles). We
furthermore stress that classical electrodynamics needs a consistent dynamical
description of the particles that involves coupled equations for the
electromagnetic fields and the trajectories [M. Brachet and E. Tirapegui, Nuovo
Cimento Soc. Ital. Fis. A 47, 210 (1978)] and any conserved quantity will then
contain contributions from both the field and the particles.",1207.4613v1
2012-08-09,Prospects of performing Lorentz invariance tests with VHE emission from pulsars,"Gamma-ray observations provide sensitive tests of Lorentz invariance
violation (LIV). At present the most sensitive tests come from observations of
transient events, gamma-ray bursts and flaring AGN. Disadvantages of transients
are that an independent confirmation by a different experiment is often not
possible and that limits cannot be improved with a longer exposure. Pulsars do
not have these disadvantages. Testing Lorentz invariance with pulsars was not
considered seriously so far because limits were not competitive. The VERITAS
collaboration has recently reported the detection of pulsed emission from the
Crab pulsar above 100 GeV. This measurement can be used to constrain LIV
effects with a sensitivity that is competitive with some of the best available
limits. In view of this unexpected result we discuss what the prospects are of
doing LIV tests with very-high energy gamma-ray emission from pulsars.",1208.2033v1
2012-08-14,"A theory of photospheric emission from relativistic, collimated outflows","Relativistic outflows in the form of jets are common in many astrophysical
objects. By their very nature, jets have angle dependent velocity profiles,
Gamma = Gamma(r, theta, phi), where Gamma is the outflow Lorentz factor. In
this work we consider photospheric emission from non-dissipative jets with
various Lorentz factor profiles, of the approximate form Gamma \approx
Gamma_0/[(theta/theta_j)^p + 1], were theta_j is the characteristic jet opening
angle. In collimated jets, the observed spectrum depends on the viewing angle,
theta_v. We show that for narrow jets (theta_j Gamma_0 \lesssim few), the
obtained low energy photon index is alpha \approx -1 (dN/dE \propto E^alpha),
independent of viewing angle, and weakly dependent on the Lorentz factor
gradient (p). A similar result is obtained for wider jets observed at theta_v
\approx theta_j. This result is surprisingly similar to the average low energy
photon index seen in gamma-ray bursts. For wide jets (theta_j Gamma_0 \gtrsim
few) observed at theta_v \ll theta_j, a multicolor blackbody spectrum is
obtained. We discuss the consequences of this theory on our understanding of
the prompt emission in gamma-ray bursts.",1208.2965v2
2012-10-03,A functional analytic approach to perturbations of the Lorentz gas,"We present a functional analytic framework based on the spectrum of the
transfer operator to study billiard maps associated with perturbations of the
periodic Lorentz gas. We show that recently constructed Banach spaces for the
billiard map of the classical Lorentz gas are flexible enough to admit a wide
variety of perturbations, including: movements and deformations of scatterers;
billiards subject to external forces; nonelastic reflections with kicks and
slips at the boundaries of the scatterers; and random perturbations comprised
of these and possibly other classes of maps. The spectra and spectral
projections of the transfer operators are shown to vary continuously with such
perturbations so that the spectral gap enjoyed by the classical billiard
persists and important limit theorems follow.",1210.1261v1
2012-10-09,Covariant Quantization of Lorentz-Violating Electromagnetism,"We present a consistent, generally covariant quantization of light for
non-vacuum birefringent, Lorentz-symmetry breaking electrodynamics in the
context of the Standard Model Extension. We find that the number of light
quanta in the field is not frame independent, and that the interaction of the
quantized field with matter is necessarily birefringent. We also show that the
conventional Lorenz gauge condition used to restrict the photon-mode basis to
solutions of the Maxwell equations must be weakened to consistently describe
Lorentz symmetry violation.",1210.2683v2
2012-10-23,Non Linear Lorentz Transformation and Doubly Special Relativity,"We generate non-linear representations of the Lorentz Group by unitary
transformation over the Lorentz generators. To do that we use deformed scale
transformations by introducing momentum-depending parameters. The momentum
operator transformation is found to be equivalent to a particle momentum
transformation. The configuration space transformation is found to depend on
the old momentum operator and we show that this transformation generates models
with two scales, one for the velocity ($c$) and another one for the energy. A
Lagrangian formalism is proposed for these models and an effective metric for
the deformed Minkowski space is found. We show that the Smolin model is one in
a family of doubly special relativity. Finally we construct an ansatz for the
quantization of such theories.",1210.6261v1
2012-10-30,Self-interacting mass-dimension one fields for any spin,"According to Ahluwalia and Grumiller, massive spin-half fields of
mass-dimension one can be constructed using the eigenspinors of the
charge-conjugation operator (Elko) as expansion coefficients. In this paper, we
generalize their result by constructing quantum fields from higher-spin Elko.
The kinematics of these fields are thoroughly investigated. Starting with the
field operators, their propagators and Hamiltonians are derived. These fields
satisfy the higher-spin generalization of the Klein-Gordon but not the Dirac
equation. Independent of the spin, they are all of mass-dimension one and are
thus endowed with renormalizable self-interactions. These fields violate
Lorentz symmetry. The violation can be characterized by a non Lorentz-covariant
term that appears in the Elko spin-sums. This term provides a decomposition of
the generalized higher-spin Dirac operator in the momentum space thus
suggesting a possible connection between the mass-dimension one fields and the
Lorentz-invariant fields.",1210.7916v6
2012-11-19,On Gravity localization under Lorentz Violation in warped scenario,"Recently Rizzo studied the Lorentz Invariance Violation (LIV) in a brane
scenario with one extra dimension where he found a non-zero mass for the
four-dimensional graviton. This leads to the conclusion that five-dimensional
models with LIV are not phenomenologically viable. In this work we re-examine
the issue of Lorentz Invariance Violation in the context of higher dimensional
theories. We show that a six-dimensional geometry describing a string-like
defect with a bulk-dependent cosmological constant can yield a massless 4D
graviton, if we allow the cosmological constant variation along the bulk, and
thus can provides a phenomenologically viable solution for the gauge hierarchy
problem.",1211.4542v1
2012-12-27,A new CPT-even and Lorentz-Violating nonminimal coupling in the Dirac equation,"In this work, we propose a CPT-even and Lorentz-violating dimension-five
nonminimal coupling between fermionic and gauge fields, involving the CTP-even
and Lorentz-violating gauge tensor of the SME. This nonminimal coupling
modifies the Dirac equation, whose nonrelativistic regime is governed by a
Hamiltonian which induces new effects, such as an electric-Zeeman-like spectrum
splitting and an anomalous-like contribution to the electron magnetic moment,
between others. Some of these new effects allows to constrain the magnitude of
this nonminimal coupling in 1 part in 10^16.",1212.6361v1
2013-01-01,Lorentz Gauge Quantization in a Cosmological Space-time,"It has recently been shown that it is not possible to impose the Lorentz
gauge condition in a cosmological space-time using the Gutpa-Bleuler method of
quantization. It was also shown that it is possible to add
$\nabla_{\mu}A^{\mu}$ as a new degree of freedom to the electromagnetic field
and that this new degree of freedom might be the dark energy which is producing
the accelerated expansion of the Universe.
  In this paper I show that the Lorentz gauge condition can be imposed using
Dirac's method of quantizing constrained dynamical systems. I also compute the
vacuum expectation value of the energy-momentum tensor and show that it
vanishes. Thus, in Dirac's approach, the electromagnetic field does not make a
contribution to the dark energy.",1301.0032v1
2013-01-18,New formulas for decreasing rearrangements and a class of Orlicz-Lorentz spaces,"Using a nonlinear version of the well known Hardy-Littlewood inequalities, we
derive new formulas for decreasing rearrangements of functions and sequences in
the context of convex functions. We use these formulas for deducing several
properties of the modular functionals defining the function and sequence spaces
$M_{\varphi,w}$ and $m_{\varphi,w}$ respectively, introduced earlier in
\cite{HKM} for describing the K\""othe dual of ordinary Orlicz-Lorentz spaces in
a large variety of cases ($\varphi$ is an Orlicz function and $w$ a {\it
decreasing} weight). We study these $M_{\varphi,w}$ classes in the most general
setting, where they may even not be linear, and identify their K\""othe duals
with ordinary (Banach) Orlicz-Lorentz spaces. We introduce a new class of
rearrangement invariant Banach spaces $\mathcal{M}_{\varphi,w}$ which proves to
be the K\""othe biduals of the $M_{\varphi,w}$ classes. In the case when the
class $M_{\varphi,w}$ is a separable quasi-Banach space,
$\mathcal{M}_{\varphi,w}$ is its Banach envelope.",1301.4465v1
2013-02-04,The consequences of complex Lorentz force and violation of Lorenz gauge condition,"The complex Lorentz force is introduced and extended to include magnetic
scalar. This scalar is found to be associated with a prevailing magnetic field
permeating the whole space. It also introduce an extra force in Lorentz complex
force. The magnetic scalar is associated with the vacuum energy. The
Proca-Maxwell's massive electrodynamics is derived from the extend
current-density transformations. Proca-Maxwell's theory is found to be
invariant under the extended gauge transformations (current-charge density).
The Lorenz gauge condition is shown to express the photon charge conservation.
Any violation of Lorenz gauge (photon charge) or electronic charge conservation
would lead to spin zero scalar particles. This is manifested in
superconductivity. The total charge comprising the electron and photon is
always conserved. Owing to superconductivity, the photon charge is related to
electron charge by $e_p=\sqrt{\frac{m_p}{m_e}}\,\,e$. Photons inside
superconductors are shown to be massive. It is shown that Maxwell's equations
expressed in complex form are more convenient to study duality transformations.",1302.0695v2
2013-02-14,Spontaneous Lorentz Violation in Gauge Theories,"Frohlich, Morchio and Strocchi long ago proved that Lorentz invariance is
spontaneously broken in QED because of infrared effects. We develop a simple
model where consequences of this breakdown can be explicitly and easily
calculated. For this purpose, the superselected U(1) charge group of QED is
extended to a superselected ""Sky"" group containing direction-dependent gauge
transformations at infinity. It is the analog of the Spi group of gravity. As
Lorentz transformations do not commute with Sky, they are spontaneously broken.
These abelian considerations and model are extended to non-Abelian gauge
symmetries. Basic issues regarding the observability of twisted non-Abelian
gauge symmetries and of the asymptotic ADM symmetries of quantum gravity are
raised.",1302.3406v2
2013-02-25,Inertial frames without the relativity principle: breaking Lorentz symmetry,"We investigate inertial frames in the absence of Lorentz invariance,
reconsidering the usual group structure implied by the relativity principle. We
abandon the relativity principle, discarding the group structure for the
transformations between inertial frames, while requiring these transformations
to be at least linear (to preserve homogeneity). In theories with a preferred
frame (aether), the set of transformations between inertial frames forms a
groupoid/pseudogroup instead of a group, a characteristic essential to evading
the von Ignatowsky theorems. In order to understand the dynamics, we also
demonstrate that the transformation rules for energy and momentum are in
general affine. We finally focus on one specific and compelling model
implementing a minimalist violation of Lorentz invariance.",1302.5989v1
2013-03-05,The photino sector and a confining potential in a supersymetric Lorentz-symmetry-violating model,"We study the spectrum of the minimal supersymmetric extension of the
Carroll-Field-Jackiw model for Electrodynamics with a topological
Chern-Simons-like Lorentz-symmetry violating term. We identify a number of
independent background fermion condensates, work out the gaugino dispersion
relation and propose a photonic effective action to consider aspects of
confinement induced by the SUSY background fermion condensates, which also
appear to signal Lorentz-symmetry violation in the photino sector of the
action. Our calculations of the static potential are carried out within the
framework of the gauge-invariant but path-dependent variables formalism which
are alternative to the Wilson loop approach. Our results show that the
interaction energy contains a linear term leading to the confinement of static
probe charges.",1303.1108v2
2013-03-07,Possible relevance of quantum spacetime for neutrino-telescope data analyses,"One of the primary goals of neutrino telescopes, such as IceCube, is the
discovery of neutrinos emitted by gamma-ray bursts (GRBs). Another source of
interest in the results obtained by these telescopes is their possible use for
tests of the applicability of Einstein's Special Relativity to neutrinos,
particularly with respect to modifications that lead to Lorentz invariance
violation that have been conjectured by some models of quantum space-time. We
examine here the fascinating scenario in which these two aspects of
neutrino-telescope physics require a combined analysis. We discuss how
neutrinos that one would not associate to a GRB, when assuming a classical
spacetime picture, may well be GRB neutrinos if the possibility that Lorentz
invariance is broken at very high energies is taken into account. As an
illustrative example we examine three IceCube high energy neutrinos that
arrived hours before GRBs (but from the same direction) and we find that the
available, IceCube data, while inconclusive, is compatible with a scenario in
which one or two of these neutrinos were GRB neutrinos and their earlier
arrival reflects Lorentz invariance violation.
  We outline how future analyses of neutrino data should be done in order to
systematically test this possibility.",1303.1826v1
2013-03-26,A new approach to test Lorentz invariance,"Lorentz invariance in the weak interaction has been tested rather poorly
compared to the electromagnetic interaction. In this work we show which tests
on the weak interaction should be considered. We focus on one particular test
that explores the spin degree of freedom in {\beta} decay. To connect various
phenomenological tests of Lorentz invariance in the weak interaction, we
exploit a new theoretical model that may provide a framework that relates the
different tests.",1303.6419v2
2013-03-28,Pre-acceleration from Landau-Lifshitz Series,"The Landau-Lifshitz equation is considered as an approximation of the
Abraham-Lorentz-Dirac equation. It is derived from the Abraham-Lorentz-Dirac
equation by treating radiation reaction terms as a perturbation. However, while
the Abraham-Lorentz-Dirac equation has pathological solutions of
pre-acceleration and runaway, the Landau-Lifshitz equation and its finite
higher order extensions are free of these problems. So it seems mysterious that
the property of solutions of these two equations is so different. In this paper
we show that the problems of pre-acceleration and runaway appear when one
consider a series of all-order perturbation which we call it the
Landau-Lifshitz series. We show that the Landau-Lifshitz series diverges in
general. Hence a resummation is necessary to obtain a well-defined solution
from the Landau-Lifshitz series. This resummation leads the pre-accelerating
and the runaway solutions. The analysis is focusing on the non-relativistic
case, but we can extend the results obtained here to relativistic case at least
in one dimension.",1303.7120v1
2013-04-01,Covariant Renormalizable Modified and Massive Gravity Theories on (Non) Commutative Tangent Lorentz Bundles,"The fundamental field equations in modified gravity (including general
relativity; massive and bimetric theories; Ho\vrava-Lifshits, HL;
Einstein--Finsler gravity extensions etc) posses an important decoupling
property with respect to nonholonomic frames with 2 (or 3) +2+2+... spacetime
decompositions. This allows us to construct exact solutions with generic
off--diagonal metrics depending on all spacetime coordinates via generating and
integration functions containing (un-) broken symmetry parameters. Such
nonholonomic configurations/ models have a nice ultraviolet behavior and seem
to be ghost free and (super) renormalizable in a sense of covariant and/or
massive modifications of HL gravity. The apparent noncommutativity and breaking
of Lorentz invariance by quantum effects can be encoded into fibers of
noncommutative tangent Lorentz bundles for corresponding ""partner""
anisotropically induced theories. We show how the constructions can be extended
to include conjectured covariant reonormalizable models with massive graviton
fields and effective Einstein fields with (non)commutative variables.",1304.1079v2
2013-04-29,Lorentz-Violating Regulator Gauge Fields as the Origin of Dynamical Flavour Oscillations,"We show how a mass mixing matrix can be generated dynamically, for two
massless fermion flavours coupled to a Lorentz invariance violating (LIV) gauge
field. The LIV features play the role of a regulator for the gap equations, and
the non-analytic dependence of the dynamical masses, as functions of the gauge
coupling, allows to consider the limit where the LIV gauge field eventually
decouples from the fermions. Lorentz invariance is then recovered, to describe
the oscillation between two free fermion flavours, and we check that the finite
dynamical masses are the only effects of the original LIV theory. We also
discuss briefly a connection of our results with the case of Majorana neutrinos
in both, the standard model, where only left-handed (active) neutrinos are
considered, and extensions thereof, with sterile right-handed neutrinos.",1304.7706v2
2013-04-30,Emergent Lorentz invariance from Strong Dynamics: Holographic examples,"We explore the phenomenon of emergent Lorentz invariance in strongly coupled
theories. The strong dynamics is handled using the gauge/gravity
correspondence. We analyze how the renormalization group flow towards Lorentz
invariance is reflected in the two-point functions of local operators and in
the dispersion relations of the bound states. The deviations of these
observables from the relativistic form at low energies are found to be
power-law suppressed by the ratio of the infrared and ultraviolet scales. We
show that in a certain subclass of models the velocities of the light bound
states stay close to the emergent `speed of light' even at high energies. We
comment on the implications of our results for particle physics and condensed
matter.",1305.0011v3
2013-05-30,The fate of Lorentz frame in the vicinity of black hole singularity,"General Relativity is known to break down at singularities. However, it is
expected that quantum corrections become important when the curvature is of the
order of Planck scale avoiding the singularity. By calculating the effect of
tidal forces on a freely falling inertial frame, and assuming the least
possible size of the frame to be of the Planck length, we show that the Lorentz
frames cease to exist at a finite distance from the singularity. Within that
characteristic radius, one cannot apply General Relativity nor Quantum Field
Theory as we know them today. Additionally we consider other quantum length
scales and impose limits on the distances from the singularity at which those
theories can conceivably be applied within a Lorentz frame.",1305.7221v1
2013-07-23,The dynamics and excitation of torsional waves in geodynamo simulations,"The predominant force balance in rapidly rotating planetary cores is between
Coriolis, pressure, buoyancy and Lorentz forces. This magnetostrophic balance
leads to a Taylor state where the spatially averaged azimuthal Lorentz force is
compelled to vanish on cylinders aligned with the rotation axis. Any deviation
from this state leads to a torsional oscillation, signatures of which have been
observed in the Earth's secular variation and are thought to influence length
of day variations via angular momentum conservation. In order to investigate
the dynamics of torsional oscillations, we perform several three-dimensional
dynamo simulations in a spherical shell. We find torsional oscillations,
identified by their propagation at the correct Alfv\'{e}n speed, in many of our
simulations. We find that the frequency, location and direction of propagation
of the waves are influenced by the choice of parameters. Torsional waves are
observed within the tangent cylinder and also have the ability to pass through
it. Several of our simulations display waves with core travel times of 4 to 6
years. We calculate the driving terms for these waves and find that both the
Reynolds force and ageostrophic convection acting through the Lorentz force are
important in driving torsional oscillations.",1307.6048v1
2013-07-26,Tests of the Lorentz and CPT Symmetries at the Planck Energy Scale with X-Ray and Gamma-Ray Observations,"X-ray and gamma-ray observations of astrophysical objects at cosmological
distances can be used to probe the energy dependence of the speed of light with
high accuracy and to search for violations of Lorentz invariance and CPT
symmetry at the Planck energy scale. In this conference contribution, we
discuss these searches in the theoretical framework of the Standard-Model
Extension. We present new limits on the dispersion relation governed by
operators of mass dimension d=5 and d=6, and we discuss avenues for future
progress.",1307.6946v1
2013-07-30,Entanglement does not generally decrease under renormalization,"Renormalization is often described as the removal or ""integrating out"" of
high energy degrees of freedom. In the context of quantum matter, one might
suspect that quantum entanglement provides a sharp way to characterize such a
loss of degrees of freedom. Indeed, for quantum many-body systems with Lorentz
invariance, such entanglement monotones have been proven to exist in one, two,
and three spatial dimensions. In each dimension d, a certain term in the
entanglement entropy of a d-ball decreases along renormalization group (RG)
flows. Given that most quantum many-body systems available in the laboratory
are not Lorentz invariant, it is important to generalize these results if
possible. In this work we demonstrate the impossibility of a wide variety of
such generalizations. We do this by exhibiting a series of counterexamples with
understood renormalization group flows which violate entanglement RG
monotonicity. We discuss bosons at finite density, fermions at finite density,
and majorization in Lorentz invariant theories, among other results.",1307.8117v2
2013-07-31,Lorentz Invariance Violation Limits from the Crab Pulsar using VERITAS,"Quantum gravity (QG) theories over the past fifty years have sought to
understand the relationship between the four fundamental interactions. A major
insight gained in this area is that all interactions could possibly unify at
Planck-scale energies ~10$^{19}$ GeV. A potential consequence of the
unification of gravity with the other three interactions would be a breaking of
Lorentz symmetry at Planck-scale energies. The interpretation of Time-of-flight
(TOF) measurements from gamma-ray telescopes have been able to put constraints
on the energy scales of the Lorentz-invariance violations (LIV). The Crab
pulsar, the only pulsar detected at very high energies (VHE, E > 100 GeV)
presents a unique opportunity to put new constraints on LIV. Presented here are
the results of observations of the Crab pulsar with VERITAS and statistical
methods to determine limits of LIV effects from energy-dependent timing
differences.",1307.8382v1
2013-10-01,Power-law distributions for the free path length in Lorentz gases,"It is well known that, in the Boltzmann-Grad limit, the distribution of the
free path length in the Lorentz gas with disordered scatterer configuration has
an exponential density. If, on the other hand, the scatterers are located at
the vertices of a Euclidean lattice, the density has a power-law tail
proportional to xi^{-3}. In the present paper we construct scatterer
configurations whose free path lengths have a distribution with tail xi^{-N-2}
for any positive integer N. We also discuss the properties of the random flight
process that describes the Lorentz gas in the Boltzmann-Grad limit. The
convergence of the distribution of the free path length follows from
equidistribution of large spheres in products of certain homogeneous spaces,
which in turn is a consequence of Ratner's measure classification theorem.",1310.0328v2
2013-10-03,Geometrodynamics and Lorentz symmetry,"We study the dynamics of gauge theory and general relativity using fields of
local observers, thus maintaining local Lorentz symmetry despite a space/time
splitting of fields. We start with Yang--Mills theory, where observer fields
are defined as normalized future-timelike vector fields. We then define
observers without a fixed geometry, and find these play two related roles in
general relativity: splitting fields into spatial and temporal parts, and
""breaking"" gauge symmetry, effectively reducing the spacetime SO(n,1)
connection to an observer-dependent spatial SO(n) connection. In both gauge
theory and gravity, the observer field reduces the action to canonical form,
without using gauge fixing. In the 4d gravity case, the result is a manifestly
Lorentz covariant counterpart of the Ashtekar-Barbero formulation. We also
explain how this leads geometrically to a picture of general relativity in
terms of ""observer space"" rather than spacetime---a setting where both
spacetime symmetry and the dynamical description are simultaneously available.",1310.1088v1
2013-11-25,Clifford Algebra and Space-Time Transformations: Lorentz Transformation and Inertial Transformation,"We review the Inertial transformation and Lorentz transformation under a new
context, by using Clifford Algebra or Geometric Algebra. The apparent
contradiction between theses two approach is simply stems from different
procedures for clock synchronization associated with different choices of the
coordinates used to describe the physical world. We find the physical and
coordinates components of both transformations. A important result is that in
the case of Inertial transformation the physical components are exactly the
Galilean transformations, but the speed of light is not c. Another interesting
result is due to the fact the Lorentz transformations lead directly to physical
components, and this case the speed of light is c. Finally e show that both
scenarios, de-synchronization Einstein theory and synchronized theory, are all
mathematically equivalent by means of Clifford Algebra Transformations.",1311.6378v1
2013-12-10,High energy emission of GRB 130821A: constraining the density profile of the circum-burst medium as well as the initial Lorentz factor of the outflow,"GRB 130821A was detected by Fermi-GBM/LAT, Konus-Wind, SPI-ACS/INTEGRAL,
RHESSI and Mars Odyssey-HEND. Although the data of GRB 130821A are very
limited, we show in this work that the high energy gamma-ray emission (i.e.,
above 100 MeV) alone imposes tight constraint on the density profile of the
circum-burst medium as well as the initial Lorentz factor of the outflow. The
temporal behavior of the high energy gamma-ray emission is consistent with the
forward shock synchrotron radiation model and the circum-burst medium likely
has a constant-density profile. The Lorentz factor is about a few hundred,
similar to other bright GRBs.",1312.2662v1
2013-12-16,Prospective constraints on Lorentz violation from ultrahigh-energy photon detection,"We point out that violation of Lorentz invariance affects the interaction of
high-energy photons with the Earth's atmosphere and magnetic field. In certain
parameter region this interaction becomes suppressed and the photons escape
observation passing through the atmosphere without producing air showers. We
argue that a detection of photon-induced air showers with energies above 10^19
eV, implying the absence of suppression as well as the absence of photon decay,
will put tight double-sided limits on Lorentz violation in the sector of
quantum electrodynamics. These constraints will be by several orders of
magnitude stronger than the existing ones and will be robust against any
assumptions about the astrophysical origin of the detected photons.",1312.4368v2
2013-12-17,Cosmic magnetization in curved and Lorentz violating space-times,"The presence of the large-scale magnetic fields is one of the greatest
puzzles of contemporary cosmology. The symmetries of the electromagnetic field
theory combined with the geometric structure of the FRW universe leads to an
adiabatic decay of the primordial magnetic fields. Due to this rapid decay the
residual large scale magnetic field is astrophysically unimportant. A common
feature among many of the proposed amplification mechanisms is the violation of
Lorentz symmetries. We introduce an amplification mechanism within a Lorentz
violating environment where we use Finsler geometry as our theoretical
background. The mechanism is based on the adoption of a local anisotropic
structure that leads to modifications on the Ricci identities. Thus, the
wave-like equation of any vector source, including the magnetic field, is
enriched by the Finslerian curvature theory. In particular limits the remaining
seed field can be strong enough to seed the galactic dynamo. In our analysis we
also develop the 1+3 covariant formalism for the 4-vector potential in curved
space-times.",1312.4631v2
2013-12-17,Quantum field theoretic properties of Lorentz-violating operators of nonrenormalizable dimension in the photon sector,"In the context of the nonminimal Standard-Model Extension a special subset of
the CPT-even higher-dimensional operators in the photon sector is discussed
from a quantum-field theoretical point of view. The modified dispersion laws,
photon polarization vectors plus the gauge field propagator are obtained and
their properties are analyzed. It is demonstrated that for certain sectors of
the modified theory a puzzle arises for the optical theorem at tree-level. This
is followed by a discussion of how it can be interpreted and resolved at first
order Lorentz violation. Furthermore the commutator of two gauge fields that
are evaluated at different spacetime points is obtained and discussed. The
structure of the theory is shown to resemble the structure of the modification
based on the corresponding dimension-4 operator. However some properties are
altered due to the nonrenormalizable nature of the theory considered. The
results provide more insight into the characteristics of Lorentz-violating
quantum field theories that rest upon contributions of nonrenormalizable
dimension.",1312.4916v1
2014-01-16,Quantitative imaging of flux vortices in type-II superconductor MgB$_2$ using Cryo-Lorentz Transmission Electron Microscopy,"Imaging of flux vortices in high quality MgB$_2$ single crystals has been
successfully performed in a commercial Field Emission Gun-based Transmission
Electron Microscope. In Cryo-Lorentz Microscopy, the sample quality and the
vortex lattice can be monitored simultaneously, allowing one to relate
microscopically the surface quality and the vortex dynamics. Such a vortex
motion ultimately determines the flow resistivity, $\rho_{f}$, the knowledge of
which is indispensable for practical applications such as superconducting
magnets or wires for Magnetic Resonance Imaging. The observed patterns have
been analyzed and compared with other studies by Cryo-Lorentz Microscopy or
Bitter decoration. We find that the vortex lattice arrangement depends strongly
on the surface quality obtained during the specimen preparation, and tends to
form an hexagonal Abrikosov lattice at a relatively low magnetic field. Stripes
or gossamer-like patterns, recently suggested as potential signatures of an
unconventional behavior of MgB$_2$, were not observed.",1401.4062v1
2014-02-11,Lorentz Force Electrical Impedance Tomography,"This article describes a method called Lorentz Force Electrical Impedance
Tomography. The electrical conductivity of biological tissues can be measured
through their sonication in a magnetic field: the vibration of the tissues
inside the field induces an electrical current by Lorentz force. This current,
detected by electrodes placed around the sample, is proportional to the
ultrasonic pressure, to the strength of the magnetic field and to the
electrical conductivity gradient along the acoustic axis. By focusing at
different places inside the sample, a map of the electrical conductivity
gradient can be established. In this study experiments were conducted on a
gelatin phantom and on a beef sample, successively placed in a 300 mT magnetic
field and sonicated with an ultrasonic transducer focused at 21 cm emitting 500
kHz bursts. Although all interfaces are not visible, in this exploratory study
a good correlation is observed between the electrical conductivity image and
the ultrasonic image. This method offers an alternative to detecting
pathologies invisible to standard ultrasonography.",1402.2573v1
2014-02-11,Lorentz-Force Hydrophone Characterization,"A Lorentz-force hydrophone consists of a thin wire placed inside a magnetic
field. When under the influence of an ultrasound pulse, the wire vibrates and
an electrical signal is induced by the Lorentz force that is proportional to
the pulse amplitude. In this study a compact prototype of such a hydrophone is
introduced and characterized, and the hydrodynamic model previously developed
is refined. It is shown that the wire tension has a negligible effect on the
measurement of pressure. The frequency response of the hydrophone reaches 1 MHz
for wires with a diameter ranging between 70 and 400 \micro m. The hydrophone
exhibits a directional response such that the signal amplitude differs by less
than 3dB as the angle of the incident ultrasound pulse varies from -20$^o$ and
+20$^o$. The linearity of the measured signal is confirmed across the 50 kPa to
10 MPa pressure range, and an excellent resistance to cavitation is observed.
This hydrophone is of interest for high pressure ultrasound measurements
including High Intensity Focused Ultrasound (HIFU) and ultrasonic measurements
in difficult environments.",1402.2578v1
2014-02-14,Einstein-Hilbert Graviton modes modified by the Lorentz-violating bumblebee Field,"In this work, we investigate the consequences of the spontaneous breaking of
Lorentz symmetry, triggered by the bumblebee vector field, on the usual
Einstein-Hilbert theory. Specifically, we consider the Einstein-Hilbert action
modified by the bumblebee dynamic field, and evaluate the graviton propagator
using an extended basis of Barnes-Rivers tensor projectors, involving the
Lorentz-violating vector. Once the propagator is carried out, we proceed with
discussing the consistency of the model, writing the dispersion relations, and
analyzing causality and unitarity. We verify that this model possesses two
dispersion relations: one provides causal and unitary propagating modes, while
the second yields a causal but nonunitary mode which spoils the physical
consistency of the model.",1402.3554v2
2014-02-23,On the field theoretical formulation of the electron-proton scattering in the Coulomb and Lorentz gauges,"The relativistic three dimensional (3D) Lippmann-Schwinger-type equations for
the $ep$ scattering amplitude is derived based on unitarity condition in the
usual quantum electrodynamic (QED). The $ep$ scattering potential $V_{e'N',eN}$
consists of the leading one off mass shell photon exchange part and the
nonlocal multi-particle exchange potential. Unlike to the other
field-theoretical equations, both protons in the unitarity condition and in
$V_{e'N',eN}$ are on mass shell. Therefore in this approach are not required
the multi-variable input photon-nucleon vertexes with the off mass shell
nucleons.
  In the present formulation the standard leading one photon exchange potential
$V_{OPE}$ is generated by the canonical equal-time anti commutator between the
electron source and the interacted electron fields which are sandwiched by the
one nucleon asymptotic states. This anticommutator is calculated in the Coulomb
and Lorentz gauges, where only the transverse parts of the photon fields are
quantized. It is shown, that the leading one photon exchange
potentialn$V_{OPE}$ in the Coulomb and Lorentz gauges coincide. The complete
set of the next to leading order terms which are generated by the static
electric (Coulomb) interaction are exactly reproduced.",1402.5641v1
2014-02-26,Tests of local Lorentz invariance violation of gravity in the standard model extension with pulsars,"Standard-model extension (SME) is an effective field theory introducing all
possible Lorentz-violating (LV) operators to the standard model (SM) and
general relativity (GR). In the pure-gravity sector of minimal SME (mSME), nine
coefficients describe dominant observable deviations from GR. We systematically
implemented twenty-seven tests from thirteen pulsar systems to tightly
constrain eight linear combinations of these coefficients with extensive Monte
Carlo simulations. It constitutes the first detailed and systematic test of the
pure-gravity sector of mSME with the state-of-the-art pulsar observations. No
deviation from GR was detected. The limits of LV coefficients are expressed in
the canonical Sun-centered celestial-equatorial frame for convenience of
further studies. They are all improved by significant factors of tens to
hundreds with existing ones. As a consequence, Einstein's equivalence principle
is verified substantially further by pulsar experiments in terms of local
Lorentz invariance in gravity.",1402.6452v2
2014-04-12,"The Lorentz force law and its connections to hidden momentum, the Einstein-Laub force, and the Aharonov-Casher effect","The Lorentz force of classical electrodynamics, when applied to magnetic
materials, gives rise to hidden energy and hidden momentum. Removing the
contributions of hidden entities from the Poynting vector, from the
electromagnetic momentum density, and from the Lorentz force and torque
densities simplifies the equations of the classical theory. In particular, the
reduced expression of the electromagnetic force-density becomes very similar
(but not identical) to the Einstein-Laub expression for the force exerted by
electric and magnetic fields on a distribution of charge, current, polarization
and magnetization. Examples reveal the similarities and differences among
various equations that describe the force and torque exerted by electromagnetic
fields on material media. An important example of the simplifications afforded
by the Einstein-Laub formula is provided by a magnetic dipole moving in a
static electric field and exhibiting the Aharonov-Casher effect.",1404.3261v1
2014-04-18,Renormalizability of Yang-Mills theory with Lorentz violation and gluon mass generation,"We show that pure Yang-Mills theories with Lorentz violation are
renormalizable to all orders in perturbation theory. To do this, we employ the
algebraic renormalization technique. Specifically, we control the breaking
terms with a suitable set of external sources which, eventually, attain certain
physical values. The Abelian case is also analyzed as a starting point. The
main result is that the renormalizability of the usual Maxwell and Yang-Mills
sectores are both left unchanged. Furthermore, in contrast to Lorentz violating
QED, the odd CPT violation sector of Yang-Mills theories renormalizes
independently. Moreover, the method induces, in a natural way, mass terms for
the gauge field while the photon remains massless (at least n the sense of a
Proca-like term). The entire analysis is carried out at the Landau gauge.",1404.4846v3
2014-07-03,Gravitational Entropy and the Second Law of Thermodynamics,"The spontaneous violation of Lorentz and diffeomorphism invariance in a phase
near the big bang lowers the entropy, allowing for an arrow of time and the
second law of thermodynamics. The spontaneous symmetry breaking leads to
$O(3,1)\rightarrow O(3)\times R$, where $O(3)$ is the rotational symmetry of
the Friedmann-Lema\^{i}tre-Robertson-Walker spacetime. The Weyl curvature
tensor $C_{\mu\nu\rho\sigma}$ vanishes in the FLRW spacetime satisfying the
Penrose zero Weyl curvature conjecture. The requirement of a measure of
gravitational entropy is discussed. The vacuum expectation value $\langle
0\vert\psi_\mu\vert 0\rangle\neq 0$ for a vector field $\psi_\mu$ acts as an
order parameter and at the critical temperature $T_c$ a phase transition occurs
breaking the Lorentz symmetry spontaneously. During the ordered $O(3)$ symmetry
phase the entropy is vanishingly small and for $T < T_c$ as the universe
expands the anti-restored $O(3,1)$ Lorentz symmetry leads to a disordered phase
and a large increase in entropy creating the arrow of time.",1407.1026v1
2014-07-23,The Nuclear Tensor Interaction in Covariant Energy Density Functional,"The origin of the nuclear tensor interaction in the covariant energy density
functional (EDF) is presented in this work, associated with the Fock diagrams
of Lorentz scalar and vector couplings. With this newly obtained relativistic
formalism of the nuclear tensor interaction, more distinct tensor effects are
found in the Fock diagrams of the Lorentz scalar and vector couplings, as
compared to the Lorentz pseudo-vector and tensor channels. A unified and
self-consistent treatment on both the nuclear tensor and spin-orbit
interactions, which dominate the spin-dependent features of the nuclear force,
is then achieved by the relativistic models. Moreover, careful analysis on the
tensor strengths indicates the reliability of the nuclear tensor interaction in
the covariant EDF for exploring the nuclear structure, excitation and decay
modes.",1407.6264v5
2014-07-25,Dual embedding of extended models with a Lorentz-breaking mass term,"In this paper, we investigate a CPT-even model with a Lorentz-violating mass
term. Such kind of models may present very interesting features like
superluminal modes of propagation or even instantaneous long-range
interactions. The mass term we investigate can be induced at classical or
quantum level in a scenario with spontaneous gauge symmetry breaking in a
gauge-Higgs model without Lorentz symmetry. We analyze the physical consistency
of the model by studying the poles of the propagator. By using the Noether
Dualization Method (NDM), we obtain a gauge invariant dual theory for this
model. The physical equivalence between the two models is investigated and a
general relation between the two propagators is obtained.",1407.6904v2
2014-09-02,Dimensional study of the dynamical arrest in a random Lorentz gas,"The random Lorentz gas is a minimal model for transport in heterogeneous
media. Upon increasing the obstacle density, it exhibits a growing subdiffusive
transport regime and then a dynamical arrest. Here, we study the dimensional
dependence of the dynamical arrest, which can be mapped onto the void
percolation transition for Poisson-distributed point obstacles. We numerically
determine the arrest in dimensions d=2-6. Comparing the results with standard
mode-coupling theory reveals that the dynamical theory prediction grows
increasingly worse with $d$. In an effort to clarify the origin of this
discrepancy, we relate the dynamical arrest in the RLG to the dynamic glass
transition of the infinite-range Mari-Kurchan model glass former. Through a
mixed static and dynamical analysis, we then extract an improved dimensional
scaling form as well as a geometrical upper bound for the arrest. The results
suggest that understanding the asymptotic behavior of the random Lorentz gas
may be key to surmounting fundamental difficulties with the mode-coupling
theory of glasses.",1409.0688v3
2014-09-04,Can the Abraham Light Momentum and Energy in a Medium Constitute a Lorentz Four-Vector?,"By analyzing the Einstein-box thought experiment with the principle of
relativity, it is shown that Abraham's light momentum and energy in a medium
cannot constitute a Lorentz four-vector, and they consequentially break global
momentum and energy conservation laws. In contrast, Minkowski's momentum and
energy always constitute a Lorentz four-vector no matter whether in a medium or
in vacuum, and the Minkowski's momentum is the unique correct light momentum. A
momentum-associated photon mass in a medium is exposed, which explains why only
the Abraham's momentum is derived in the traditional ""center-of-mass-energy""
approach. The EM boundary-condition matching approach, combined with Einstein
light-quantum hypothesis, is proposed to analyze this thought experiment, and
it is found for the first time that only from Maxwell equations without resort
to the relativity, the correctness of light momentum definitions cannot be
identified. Optical pulling effect is studied as well.",1409.4623v1
2014-09-17,Boosting QED and QCD bound states in the path integral formalism,"Wave functions and energy eigenvalues of the path integral Hamiltonian are
studied in Lorentz frame moving with velocity $v$. The instantaneous
interaction produced by the Wilson loop is shown to be reduced by an overall
factor $\sqrt{1-(\frac{v}{c})^2}$. As a result one obtains the boosted energy
eigenvalues in the Lorentz covariant form $E= \sqrt{\veP^2+M^2_0}$, where $M_0$
is the c.m. energy, and this form is tested for two free particles and for the
Coulomb and linear interaction.Using Lorentz contracted wave functions of the
bound states one obtains the scaled parton wave functions and valence quark
distributions for large $P$. Matrix elements containing wave functions moving
with different velocities strongly decrease with growing relative momentum,
e.g. for the time-like formfactors one obtains $F_h(Q_0)\sim
(\frac{M_h}{Q_0})^{2 n_h} $ with $n_h = 1$ and 2 for mesons and baryons, as in
the ""quark counting rule"".",1409.4964v3
2014-11-01,"Gauge invariance, Lorentz covariance and canonical quantization in nucleon structure studies","There are different operators of quark and gluon momenta, orbital angular
momenta, and gluon spin in the nucleon structure study. The precise meaning of
these operators are studied based on gauge invariance, Lorentz covariance and
canonical quantization rule. The advantage and disadvantage of different
definitions are analyzed. A gauge invariant canonical decomposition of the
total momentum and angular momentum into quark and gluon parts is suggested
based on the decomposition of the gauge potential into gauge invariant
(covariant) physical part and gauge dependent pure gauge part. Challenges to
this proposal are answered.
  \keywords{Physical and pure gauge potentials; Gauge invariant canonical quark
and gluon momenta, orbital angular momenta and spins; Homogeneous and
non-homogeneous Lorentz transformations; Gauge invariant decomposition and
gauge invariant extension; Classical and quantum measurements.",1411.0077v1
2014-11-17,Influence of an AGN complex photon field on the jet bulk Lorentz factor through Compton rocket effect,"AGNs jets are known to display relativistic motion on parsec scales but the
accelerating mechanism as well as the exact bulk Lorentz factor of the flow are
still a matter of discussion. Under certain assumptions, a plasma can be
accelerated to relativistic speeds through the Compton rocket effect. Here, we
study this effect and the resulting bulk Lorentz factor in the complex
environment of an AGN including various external sources. This is the
proceedings to the IAU Symposium 313.",1411.4571v1
2014-12-10,Local Varying-Alpha Theories,"In a recent paper we demonstrated how the simplest model for varying alpha
may be interpreted as the effect of a dielectric material, generalized to be
consistent with Lorentz invariance. Unlike normal dielectrics, such a medium
cannot change the speed of light, and its dynamics obey a Klein-Gordon
equation. This work immediately suggests an extension of the standard theory,
even if we require compliance with Lorentz invariance. Instead of a wave
equation, the dynamics may satisfy a local algebraic relation involving the
permittivity and the properties of the electromagnetic field, in analogy with
more conventional dielectric (but still preserving Lorentz invariance). We
develop the formalism for such theories and investigate some phenomenological
implications. The problem of the divergence of the classical self-energy can be
solved, or at least softened, in this framework. Some interesting new
cosmological solutions for the very early universe are found, including the
possibility of a bounce, inflation and expansion with a loitering phase, all of
which are induced by early variations in alpha.",1412.3278v2
2014-12-22,On the duality in CPT-even Lorentz-breaking theories,"In this paper, we generalize the duality between self-dual and
Maxwell-Chern-Simons theories for the case of a CPT-even Lorentz-breaking
extension of these theories. The duality is demonstrated with use of the gauge
embedding procedure, both in free and coupled cases, and with the master action
approach. The physical spectra of both Lorentz-breaking theories are studied.
The massive poles are shown to coincide and to respect the requirements for
unitarity and causality at tree level. The extra massless poles which are
present in the dualized model are shown to be nondynamical.",1412.6957v2
2015-01-01,Chiral Thirring-Wess model with Faddeevian Regularization,"Replacing vector type of interaction of the Thirring-Wess model by the chiral
type a new model is presented which is termed here as chiral Thirring-Wess
model. Ambiguity parameters of regularization is so chosen that the model falls
into the Faddeevian class.
  The resulting Faddeevian class of model in general do not possess Lorentz
invariance. However we can exploit the arbitrariness admissible in the
ambiguity parameters to relate the quantum mechanically generated ambiguity
parameters with the classical parameter involved in the masslike term of the
gauge field which helps to maintain physical Lorentz invariance instead of the
absence of manifestly lorentz covariance of the model. The the phase space
structure and the theoretical spectrum of this class of model has been
determined through Dirac's method of quantization of constraint system.",1501.00290v1
2015-01-20,A mathematical and numerical framework for magnetoacoustic tomography with magnetic induction,"We provide a mathematical analysis and a numerical framework for
magnetoacoustic tomography with magnetic induction. The imaging problem is to
reconstruct the conductivity distribution of biological tissue from
measurements of the Lorentz force induced tissue vibration. We begin with
reconstructing from the acoustic measurements the divergence of the Lorentz
force, which is acting as the source term in the acoustic wave equation. Then
we recover the electric current density from the divergence of the Lorentz
force. To solve the nonlinear inverse conductivity problem, we introduce an
optimal control method for reconstructing the conductivity from the electric
current density. We prove its convergence and stability. We also present a
point fixed approach and prove its convergence to the true solution. A new
direct reconstruction scheme involving a partial differential equation is then
proposed based on viscosity-type regularization to a transport equation
satisfied by the electric current density field. We prove that solving such an
equation yields the true conductivity distribution as the regularization
parameter approaches zero. Finally, we test the three schemes numerically in
the presence of measurement noise, quantify their stability and resolution, and
compare their performance.",1501.04803v2
2015-01-28,Einstein-Yang-Mills-Lorentz black holes,"Different black hole solutions of the coupled Einstein-Yang-Mills equations
have been well known for a long time. They have attracted much attention from
mathematicians and physicists since their discovery. In this work, we analyze
black holes associated with the gauge Lorentz group. In particular, we study
solutions which identify the gauge connection with the spin connection. This
ansatz allows one to find exact solutions to the complete system of equations.
By using this procedure, we show the equivalence between the Yang-Mills-Lorentz
model in curved space-time and a particular set of extended gravitational
theories.",1501.07234v3
2015-02-04,Robustness of the O($N$) universality class,"We calculate the critical exponents for Lorentz-violating O($N$)
$\lambda\phi^{4}$ scalar field theories by using two independent methods. In
the first situation we renormalize a massless theory by utilizing normalization
conditions. An identical task is fulfilled in the second case in a massive
version of the same theory, previously renormalized in the BPHZ method in four
dimensions. We show that although the renormalization constants, the $\beta$
and anomalous dimensions acquire Lorentz-violating quantum corrections, the
outcome for the critical exponents in both methods are identical and
furthermore they are equal to their Lorentz-invariant counterparts. Finally we
generalize the last two results for all loop levels and we provide symmetry
arguments for justifying the latter.",1502.01289v1
2015-02-09,The local geometry of compact homogeneous Lorentz spaces,"In 1995, S. Adams and G. Stuck as well as A. Zeghib independently provided a
classification of non-compact Lie groups which can act isometrically and
locally effectively on compact Lorentzian manifolds. In the case that the
corresponding Lie algebra contains a direct summand isomorphic to the
two-dimensional special linear algebra or to a twisted Heisenberg algebra,
Zeghib also described the geometric structure of the manifolds. Using these
results, we investigate the local geometry of compact homogeneous Lorentz
spaces whose isometry groups have non-compact connected components. It turns
out that they all are reductive. We investigate the isotropy representation and
curvatures. In particular, we obtain that any Ricci-flat compact homogeneous
Lorentz space is flat or has compact isometry group.",1502.02622v1
2015-02-24,Remarks on the renormalization properties of Lorentz and CPT violating quantum electrodynamics,"In this work, we employ algebraic renormalization technique to show the
renormalizability to all orders in perturbation theory of the Lorentz and CPT
violating QED. Essentially, we control the breaking terms by using a suitable
set of external sources. Thus, with the symmetries restored, a perturbative
treatment can be consistently employed. After showing the renormalizability,
the external sources attain certain physical values, which allow the recovering
of the starting physical action. The main result is that the original QED
action presents the three usual independent renormalization parameters. The
Lorentz violating sector can be renormalized by nineteen independent
parameters. Moreover, vacuum divergences appear with extra independent
renormalization. Remarkably, the bosonic odd sector (Chern-Simons-like term)
does not renormalize. One-loop computations are also presented and compared
with the existing literature.",1502.06881v2
2015-02-25,Solution to the $β$-functions in Lorentz-violating theories as a decomposition into irreducible representations,"We analyze the $\beta$-functions of Yukawa and electromagnetic theories with
Lorentz violation (LV) and propose an alternative method to find the scale
dependence of the different fields that parametrize such violations. The method
of solution consists of decomposing a family of parameters into their
irreducible representations and thus generating a group of subfamilies that
obey the same symmetries and transformation rules. This method allows us to
decouple the differential equations describing the $\beta$-functions and find
out if whether they are positive or not. For a set of parameters describing a
Lorentz-violating theory, we expect their associated $\beta$-functions to be
nonnegative or, otherwise, their scale dependence to be weak enough. These
conditions rely on the fact that asymptotically-free parameters can leave high
imprints of LV at low energies, which are ruled out by observations. Besides
imposing some constrains on the coefficients that describe LV, this method can
be used to extract irrelevant coefficients with no scale dependence.",1502.07178v2
2015-02-26,He-McKellar-Wilkens-type effect from the Lorentz symmetry breaking effects,"From the effects of the Lorentz symmetry violation in the CPT-even gauge
sector of Standard Model Extension, we establish a possible scenario where an
analogue of the He-McKellar-Wilkens effect can stem from. Besides, we build
quantum holonomies associated with the analogue of the He-McKellar-Wilkens
effect and discuss a possible analogy with the holonomic quantum computation
[P. Zanardi and M. Rasetti, Phys. Lett. A {\bf264}, 94 (1999)]. Finally, we
investigate the dependence of the energy levels on the He-McKellar-Wilkens
geometric phase induced by Lorentz symmetry breaking effects when the particle
is confined to a hard-wall confining potential.",1502.07515v1
2015-03-03,All-loop order critical exponents for massless scalar field theory with Lorentz violation in the BPHZ method,"We compute analytically the all-loop level critical exponents for a massless
thermal Lorentz-violating O($N$) self-interacting $\lambda\phi^{4}$ scalar
field theory. For that, we evaluate, firstly explicitly up to next-to-leading
order and later in a proof by induction up to any loop level, the respective
$\beta$-function and anomalous dimensions in a theory renormalized in the
massless BPHZ method, where a reduced set of Feynman diagrams to be calculated
is needed. We investigate the effect of the Lorentz violation in the outcome
for the critical exponents and present the corresponding mathematical
explanation and physical interpretation.",1503.00896v1
2015-04-06,Limiting Lorentz Violation from Neutron--Antineutron Oscillation,"We point out that if neutron--antineutron oscillation is observed in a free
neutron oscillation experiment, it will put an upper limit on the strengths of
Lorentz invariance violating (LIV) mass operators for neutrons at the level of
$10^{-23}$ GeV or so, which would be the most stringent LIV limit for neutrons.
We also study constraints on $\Delta B=2$ LIV operators and find that for one
particular operator degaussing is not necessary to obtain a visible signal. We
also note that observation of $n-\bar{n}$ oscillation signal in the nucleon
decay search experiment involving nuclei does not lead to any limit on LIV
operators since the nuclear potential difference between neutron and
antineutrons will mask any Lorentz violating effect.",1504.01176v2
2015-05-15,On the anomalies in Lorentz-breaking theories,"In this paper, we discuss the chiral anomaly in a Lorentz-breaking extension
of QED which, besides the common terms that are present in the Standard Model
Extension, includes some dimension-five nonminimal couplings. We find, using
the Fujikawa formalism, that these nonminimal couplings induce new terms in the
anomaly which depend on the Lorentz-violating parameters. Perturbative
calculations are also carried out in order to investigate whether or not new
ambiguous Carroll-Field-Jackiw terms are induced in the effective action.",1505.04047v3
2015-05-15,The Casimir effect for a stack of conductive planes,"The Casimir interaction in a stack of equally spaced infinitely thin layers
is investigated within the zero-frequency mode summation method. The response
properties are considered to be described by a constant conductivity or by a
Drude-Lorentz model with a finite set of oscillators consistent with the
optical characteristics for graphite. It is found that the asymptotic distance
dependence is affected significantly by the specific response. While the energy
is $\sim 1/d^3$ for the constant conductivity model, the energy exhibits
fractional dependence $\sim 1/d^{5/2}$ for the Drude-Lorentz description. The
Casimir force on a plane is also strongly dependent upon the particular plane
location in the stack. Furthermore, the calculated Casimir energy within the
Drude-Lorentz model yields results in good agreement with measured cohesion
energy in graphite.",1505.04169v1
2015-06-05,Spinor description of $D=5$ massless low-spin gauge fields,"Spinor description for the curvatures of $D=5$ Yang-Mills, Rarita-Schwinger
and gravitational fields is elaborated. Restrictions imposed on the curvature
spinors by the dynamical equations and Bianchi identities are analyzed. In the
absence of sources symmetric curvature spinors with $2s$ indices obey
first-order equations that in the linearized limit reduce to Dirac-type
equations for massless free fields. These equations allow for a higher-spin
generalization similarly to $4d$ case. Their solution in the form of the
integral over Lorentz-harmonic variables parametrizing coset manifold
$SO(1,4)/(SO(1,1)\times ISO(3))$ isomorphic to the three-sphere is considered.
Superparticle model that contains such Lorentz harmonics as dynamical
variables, as well as harmonics parametrizing the two-sphere $SU(2)/U(1)$ is
proposed. The states in its spectrum are given by the functions on $S^3$ that
upon integrating over the Lorentz harmonics reproduce on-shell symmetric
curvature spinors for various massless supermultiplets of $D=5$ space-time
supersymmetry.",1506.01881v2
2015-06-20,On the Theory of Lorentz Surfaces with Parallel Normalized Mean Curvature Vector Field in Pseudo-Euclidean 4-Space,"We develop an invariant local theory of Lorentz surfaces in pseudo-Euclidean
4-space by use of a linear map of Weingarten type. We find a geometrically
determined moving frame field at each point of the surface and obtain a system
of geometric functions. We prove a fundamental existence and uniqueness theorem
in terms of these functions. On any Lorentz surface with parallel normalized
mean curvature vector field we introduce special geometric (canonical)
parameters and prove that any such surface is determined up to a rigid motion
by three invariant functions satisfying three natural partial differential
equations. In this way we minimize the number of functions and the number of
partial differential equations determining the surface, which solves the
Lund-Regge problem for this class of surfaces.",1506.06242v1
2015-06-22,Far-infrared absorption of undoped and Br-doped carbon nanofiber powder in stacked-cup cone configuration,"We carried out room-temperature far-infrared (40--650~cm$^{-1}$) transmission
measurements on undoped and bromine-doped powder samples of carbon nanofibers
in stacked-cup cone geometry. The transmission spectra of both doped and
undoped samples were fit to a Drude-Lorentz model. A single Drude component and
a small bandgap (around 8~meV) semiconducting Lorentzian component along with 3
other Lorentz components were essential to get a good fit in the entire
measured frequency range. A decreased metallic conductivity along with a
red-shift of the lowest semiconducting gap was found after bromine doping. A
significant decrease in the scattering rate upon heavy doping has been
qualitatively explained as partial ordering of intercalated dopant ions.
Absorption spectra were derived from the transmission spectra under the
assumption of non-dispersive reflectance. These spectra were compared to
Drude-Lorentz model absorption spectra. The free-carrier density of the n-type
powder and the electronic mean free path were estimated and compared with
previously reported values for single-walled nanotubes and pyrolytic graphite.",1506.06667v2
2015-07-23,Non-linear eigenvalue problems and applications to photonic crystals,"We establish new analytic and numerical results on a general class of
rational operator Nevanlinna functions that arise e.g. in modelling photonic
crystals. The capability of these dielectric nano-structured materials to
control the flow of light depends on specific features of their eigenvalues.
Our results provide a complete spectral analysis including variational
principles and two-sided estimates for all eigenvalues along with numerical
implementations. They even apply to multi-pole Lorentz models of permittivity
functions and to the eigenvalues between the poles where classical min-max
variational principles fail completely. In particular, we show that our
abstract two-sided eigenvalue estimates are optimal and we derive explicit
bounds on the band gap above a Lorentz pole. A high order finite element method
is used to compute the two-sided estimates of a selection of eigenvalues for
several concrete Lorentz models, e.g. polaritonic materials and multi-pole
models.",1507.06381v1
2015-07-24,Magicity of neutron-rich isotopes within relativistic self-consistent approaches,"The formation of new shell gaps in intermediate mass neutron-rich nuclei is
investigated within the relativistic Hartree-Fock-Bogoliubov theory, and the
role of the Lorentz pseudo-vector and tensor interactions is analyzed. Based on
the Foldy-Wouthuysen transformation, we discuss in detail the role played by
the different terms of the Lorentz pseudo-vector and tensor interactions in the
appearing of the $N=16$, 32 and 34 shell gaps. The nuclei $^{24}$O, $^{48}$Si
and $^{52,54}$Ca are predicted with a large shell gap and zero ($^{24}$O,
$^{52}$Ca) or almost zero ($^{48}$Si, $^{54}$Ca) pairing gap, making them
candidates for new magic numbers in exotic nuclei. We find from our analysis
that the Lorentz pseudo-vector and tensor interactions induce very specific
evolutions of single-particle energies, which could clearly sign their presence
and reveal the need for relativistic approaches with exchange interactions.",1507.06918v2
2015-07-27,Lorentz TEM imaging of stripe structures embedded in a soft magnetic matrix,"N\'eel walls in soft magnetic NiFe/NiFeGa hybrid stripe structures surrounded
by a NiFe film are investigated by high resolution Lorentz transmission
electron microscopic imaging. An anti-parallel orientation of magnetization in
1000 nm wide neighboring unirradiated-irradiated stripes is observed by forming
high angle domain walls during magnetization reversal. Upon downscaling the
stripe structure size from 1000 nm to 200 nm a transition from a discrete
domain pattern to an effective magnetic medium is observed for external
magnetic field reversal. This transition is associated with vanishing ability
of hosting high angle domain walls between adjacent stripes. The investigation
also demonstrated the potentiality of Lorentz microscopy to image periodic
stripe structures well under micron length-scale.",1507.07313v1
2015-08-11,Bounds on higher-order Lorentz-violating photon sector coefficients from an asymmetric optical ring resonator experiment,"Optical resonators provide a powerful tool for testing aspects of Lorentz
invariance. Here, we present a reanalysis of an experiment where a path
asymmetry was created in an optical ring resonator by introducing a dielectric
prism in one arm. The frequency difference of the two fundamental
counter-propagating modes was then recorded as the apparatus was
orientation-modulated in the laboratory. By assuming that the minimal
Standard-Model Extension coefficients vanish we are able to place bounds on
higher-order parity-odd Lorentz-violating coefficients of the Standard-Model
Extension. The results presented in this work set the first constraints on two
previously unbounded linear combinations of d=8 parity-odd nonbirefringent
nondispersive coefficients of the photon sector.",1508.02490v1
2015-08-13,Communication between inertial observers with partially correlated reference frames,"In quantum communication protocols the existence of a shared reference frame
between two spatially separated parties is normally presumed. However, in many
practical situations we are faced with the problem of misaligned reference
frames. In this paper, we study communication between two inertial observers
who have partial knowledge about the Lorentz transformation that relates their
frames of reference. Since every Lorentz transformation can be decomposed into
a pure boost followed by a rotation, we begin by analysing the effects on
communication when the parties have partial knowledge about the transformation
relating their frames, when the transformation is either a rotation or pure
boost. This then enables us to investigate how the efficiency of communication
is affected due to partially correlated inertial reference frames related by an
arbitrary Lorentz transformation. Furthermore, we show how the results of
previous studies where reference frames are completely uncorrelated are
recovered from our results in appropriate limits.",1508.03341v2
2015-08-18,Experimental Demonstration of a Synthetic Lorentz Force by Using Radiation Pressure,"Synthetic magnetism in cold atomic gases opened the doors to many exciting
novel physical systems and phenomena. Ubiquitous are the methods used for the
creation of synthetic magnetic fields. They include rapidly rotating
Bose-Einstein condensates employing the analogy between the Coriolis and the
Lorentz force, and laser-atom interactions employing the analogy between the
Berry phase and the Aharonov-Bohm phase. Interestingly, radiation pressure -
being one of the most common forces induced by light - has not yet been used
for synthetic magnetism. We experimentally demonstrate a synthetic Lorentz
force, based on the radiation pressure and the Doppler effect, by observing the
centre-of-mass motion of a cold atomic cloud. The force is perpendicular to the
velocity of the cold atomic cloud, and zero for the cloud at rest. Our novel
concept is straightforward to implement in a large volume, for a broad range of
velocities, and can be extended to different geometries.",1508.04258v1
2015-09-17,QCD Breaks Lorentz Invariance and Colour,"In a previous work [1], we have argued that the algebra of non-abelian
superselection rules is spontaneously broken to its maximal abelian subalgebra,
that is, the algebra generated by its completing commuting set (the two
Casimirs and a basis of its Cartan subalgebra). In this paper, alternative
arguments confirming these results are presented. In addition, Lorentz
invariance is shown to be broken in QCD, just as it is in QED. The experimental
consequences of these results include fuzzy mass and spin shells of coloured
particles like quarks, and decay life times which depend on the frame of
observation [2-4].
  In a paper under preparation, these results are extended to the ADM
Poincar\'e group and the local Lorentz group of frames. The renormalisation of
the ADM energy by infrared gravitons is also studied and estimated.",1509.05235v2
2015-10-27,An Experiment About Parallel Circuit And The Lorentz Forces On Wires,"Parallel circuit and the Lorentz forces on current carrying wires are
important concepts in introductory physics courses. Here we describe an
experiment that illustrates these two concepts. We mount a circuit with
multiple grounding points onto a torsion balance. We show that the grounding
points create parallel return paths for the supply current. When the topology
or the shapes of the return paths are altered, the Lorentz forces exerted by
the currents in the return paths within a magnetic field change accordingly,
which in turn cause changes in the rotary displacement of the torsion balance.
This experiment is simple and can be easily reproduced in a teaching
laboratory. What makes it interesting to students is that recently two research
teams have attempted to detect thrusts from microwave driven asymmetrical
resonance cavities (EmDrive or Cannae Drive), and the phenomenon observable in
this experiment provides an alternative explanation to the thrusts they
detected.",1510.07752v1
2015-11-01,Efficient algorithms for general periodic Lorentz gases in two and three dimensions,"We present efficient algorithms to calculate trajectories for periodic
Lorentz gases consisting of square lattices of circular obstacles in two
dimensions, and simple cubic lattices of spheres in three dimensions; these
become increasingly efficient as the radius of the obstacles tends to 0, the
so-called Boltzmann-Grad limit. The 2D algorithm applies continued fractions to
obtain the exact disc with which a particle will collide at each step, instead
of using periodic boundary conditions as in the classical algorithm. The 3D
version incorporates the 2D algorithm by projecting to the three coordinate
planes. As an application, we calculate distributions of free path lengths
close to the Boltzmann-Grad limit for certain Lorentz gases. We also show how
the algorithms may be applied to deal with general crystal lattices.",1511.00236v1
2015-11-03,Constraints on mass dimension one fermionic dark matter from the Yukawa interaction,"We study the loop corrections to the scalar propagator and the fermionic
self-energy for the mass dimension one fermionic dark matter with the Yukawa
interaction. We find, in the former case, there is a non-vanishing
Lorentz-violating term while the later is Lorentz-invariant. Our study of the
fermionic loop correction shows that unitarity demands the fermionic mass must
be at least half of the bosonic mass and that the Lorentz-violating term makes
a non-trivial correction to the bosonic propagator. We discuss what these
results mean in the context of the Standard Model and the possibility of
bypassing the unitarity constraint. In the simplest scenario, within the
framework of standard quantum field theory, by identifying the scalar boson to
be the Higgs boson with a mass of 125 GeV, the mass of the fermion must be at
least 62.5 GeV.",1511.01160v4
2015-11-05,Quasilocal first law of black hole dynamics from local Lorentz transformations,"Quasilocal formulations of black hole are of immense importance since they
reveal the essential and minimal assumptions required for a consistent
description of black hole horizon, without relying on the asymptotic boundary
conditions on fields. Using the quasilocal formulation of Isolated Horizons, we
construct the Hamiltonian charges corresponding to local Lorentz
transformations on a spacetime admitting isolated horizon as an internal
boundary. From this construction, it arises quite generally that the
\emph{area} of the horizon of an isolated black hole is the Hamiltonian charge
for local Lorentz boost on the horizon. Using this argument further, it is
shown that, observers at a fixed proper distance $l_{0}$, very close to the
horizon, may define a notion of horizon energy given by $E=A/8\pi G l_{0}$, the
surface gravity is given by $\kappa=1/l_{0}$, and consequently, the first law
can be written in the quasilocal setting as $\delta E=(\kappa/8\pi G)\delta
A$..",1511.01709v2
2015-11-06,Black hole entropy arising from massless scalar field with Lorentz violation induced by the coupling to Einstein tensor,"We have investigated quantum entropy of a static black hole arising from the
massless scalar field with Lorentz violation induced by the coupling to
Einstein tensor. Our results show that the coupled massless scalar field
contributes to the classical Bekenstein-Hawking term in the black hole entropy.
The corrected classical Bekenstein-Hawking entropy is not one quarter of the
event horizon area of the original background black hole, but of a
corresponding effective metric related to the coupling. It means that the
classical Bekenstein-Hawking entropy depends not only on the black hole
parameter, but also on the coupling which reduces Lorentz violation.",1511.02004v2
2015-11-11,"Quantum deformations of D=4 Euclidean, Lorentz, Kleinian and quaternionic o^*(4) symmetries in unified o(4;C) setting","We employ new calculational technique and present complete list of classical
$r$-matrices for $D=4$ complex homogeneous orthogonal Lie algebra
$\mathfrak{o}(4;\mathbb{C})$, the rotational symmetry of four-dimensional
complex space-time. Further applying reality conditions we obtain the classical
$r$-matrices for all possible real forms of $\mathfrak{o}(4;\mathbb{C})$:
Euclidean $\mathfrak{o}(4)$, Lorentz $\mathfrak{o}(3,1)$, Kleinian
$\mathfrak{o}(2,2)$ and quaternionic $\mathfrak{o}^{\star}(4)$ Lie algebras.
For $\mathfrak{o}(3,1)$ we get known four classical $D=4$ Lorentz $r$-matrices,
but for other real Lie algebras (Euclidean, Kleinian, quaternionic) we provide
new results and mention some applications.",1511.03653v3
2015-11-19,Algebraic vacuum limits of QCD condensates from in-medium projections of Lorentz tensors,"Utilizing the in-medium Lorentz decomposition of operators generating QCD
condensates we derive general constraints among the latter ones by the
requirement of a smooth transition from medium to vacuum. In this way we relate
the vacuum limits of heretofore unrelated condensates and provide consistency
checks for the vacuum saturation hypothesis and the heavy quark mass expansion.
The results are general and depend only on the rank and symmetry of the Lorentz
tensors to be decomposed. The derived prescription enables to uniquely and
directly identify operator product expansion contributions which are
algebraically specific for in-medium situations and in particular useful for
operators with a higher rank, i.e. larger than three. Four-quark condensates in
mass dimension six are exemplified.",1511.06234v1
2015-11-25,Zero mean curvature entire graphs of mixed type in Lorentz-Minkowski 3-space,"It is classically known that the only zero mean curvature entire graphs in
the Euclidean 3-space are planes, by Bernstein's theorem. A surface in
Lorentz-Minkowski 3-space $\boldsymbol{R}^3_1$ is called of mixed type if it
changes causal type from space-like to time-like. In $\boldsymbol{R}^3_1$,
Osamu Kobayashi found two zero mean curvature entire graphs of mixed type that
are not planes. As far as the authors know, these two examples were the only
known examples of entire zero mean curvature graphs of mixed type without
singularities. In this paper, we construct several families of real analytic
zero mean curvature entire graphs of mixed type in Lorentz-Minkowski $3$-space.
The entire graphs mentioned above lie in one of these classes.",1511.07954v2
2016-02-03,Acceleration toward polarization singularity inspired by relativistic ExB drift,"The relativistic trajectory of a charged particle driven by the Lorentz force
is different from the classical one, by velocity-dependent relativistic
acceleration term. Here we show that the evolution of optical polarization
states near the polarization singularity can be described in analogy to the
relativistic dynamics of charged particles. A phase transition in parity-time
symmetric potentials is then interpreted in terms of the competition between
electric and magnetic 'pseudo'-fields applied to polarization states. Based on
this Lorentz pseudo-force representation, we reveal that zero Lorentz
pseudo-force is the origin of recently reported strong polarization convergence
to the singular state at the exceptional point. We also demonstrate the
deterministic design of achiral and directional eigenstates at the exceptional
point, allowing an anomalous linear polarizer which operates orthogonal to
forward and backward waves. Our results linking parity-time symmetry and
relativistic electrodynamics show that previous PT-symmetric potentials for the
polarization singularity with a chiral eigenstate are the subset of optical
potentials for the ExB ""polarization"" drift.",1602.01281v3
2016-02-23,Symmetries and Fields in Randers-Finsler spacetime,"We study the symmetries of the Lorentz violating Randers-Finsler spacetime.
The privileged frame defined by the background vector diagonalises the deformed
mass-shell and provides an anisotropic observer transformations. The particle
Randers transformations are achieved through the Finslerian Killing equation
which also shows the equivalence between observer and particle Randers
transformation. For a constant background vector, the Randers transformations
can be regarded as a deformed directional-dependent Poincar\'e transformation.
The Randers algebra is a deformed Poincar\'e algebra whose structure
coefficients are given by the Randers metric. We propose a field theory
invariant over the Randers transformations. The dynamics exhibits nonlocal
operators which yields to Lorentz violating terms of the nonminimal SME. The
relation and implications of the Randers algebra with other Lorentz violating
theories are discussed.",1602.07345v1
2016-02-29,Symanzik-Becchi-Rouet-Stora lessons on renormalizable models with broken symmetry: the case of Lorentz violation,"In this paper, we revisit the issue intensively studied in recent years on
the generation of terms by radiative corrections in models with broken Lorentz
symmetry. The algebraic perturbative method of handling the problem of
renormalization of the theories with Lorentz symmetry breaking, is used. We
hope to make clear the Symanzik's aphorism: ""{\it Whether you like it or not,
you have to include in the lagrangian all counter terms consistent with
locality and power-counting, unless otherwise constrained by Ward identities.}""",1602.09091v2
2016-04-03,Absence of the Gribov ambiguity in a quadratic gauge,"The Gribov ambiguity exists in various gauges except algebraic gauges.
However, algebraic gauges are not Lorentz invariant, which is their fundamental
flaw. In addition, they are not generally compatible with the boundary
conditions on the gauge fields, which are needed to compactify the space i.e.,
the ambiguity continues to exist on a compact manifold. Here we discuss a
quadratic gauge fixing, which is Lorentz invariant. We consider an example of a
spherically symmetric gauge field configuration in which we prove that this
Lorentz invariant gauge removes the ambiguity on a compact manifold
$\mathbb{S}^3$, when a proper boundary condition on the gauge configuration is
taken into account. Thus, providing one example where the ambiguity is absent
on a compact manifold in the algebraic gauge. We also show that the \tmem{BRST}
invariance is preserved in this gauge.",1604.00674v1
2016-04-05,Lab-based limits on the Carroll-Field-Jackiw Lorentz-violating electrodynamics,"The CPT-odd and Lorentz-violating Carroll-Field-Jackiw modification of
electrodynamics is discussed and we study its effects on the energy spectrum of
hydrogen, as well as in the generation of a momentum-dependent electric dipole
moment for charged leptons. We also briefly comment on the possibility of the
detection of Lorentz violation in measurements of vacuum birefringence in
resonant cavities. The bounds found are based on local laboratory experimental
limits and are not competitive with the ones coming from astrophysical
considerations.",1604.01102v4
2016-04-22,On the CPT-even Lorentz-breaking extension of the QED,"In this paper, we describe the quantum electrodynamics added by
Lorentz-violating CPT-even terms in the context of the standard model
extension. We focus our attention on the fermion sector, represented by the
CPT-even symmetric Lorentz-breaking tensor $c_{\mu\nu}$. We adopt a generic
form that parametrizes the components of $c_{\mu\nu}$ in terms of one
four-vector, namely, $c_{\mu\nu}=u_\mu u_\nu - \zeta \frac{u^2}{4}g_{\mu\nu}$.
We then generate perturbatively, up to the third order in this tensor, the
aether-like term for the gauge field. Finally, we discuss the renormalization
scheme for the gauge propagator, by taking into account $c_{\mu\nu}$ traceless
($\zeta=1)$ and, trivially, $c_{\mu\nu}=u_\mu u_\nu$ ($\zeta=0$).",1604.06647v3
2016-06-09,How is Lorentz Invariance encoded in the Hamiltonian?,"One of the disadvantages of the Hamiltonian formulation is that Lorentz
invariance is not manifest in the former. Given a Hamiltonian, there is no
simple way to check whether it is relativistic or not. One would either have to
solve for the equations of motion or calculate the Poisson Brackets of the
Noether charges to perform such a check. In this paper we show that, for a
class of Hamiltonians, it is possible to check Lorentz invariance directly from
the Hamiltonian. Our work is particularly useful for theories where the other
methods may not be readily available.",1606.02853v2
2016-06-22,Kondo effect from a Lorentz-violating domain wall description of superconductivity,"We extend recent results on domain wall description of superconductivity in
an Abelian Higgs model by introducing a particular Lorentz-violating term. The
temperature of the system is interpreted through the fact that the soliton
following accelerating orbits is a Rindler observer experiencing a thermal
bath. We show that this term can be associated with the {\sl Kondo effect},
that is, the Lorentz-violating parameter is closely related to the
concentration of magnetic impurities living on a superconducting domain wall.
We also found that the critical temperature decreasing with the impurity
concentration as a non single-valued function, for the case $T_K < T_{c0}$,
develops a negative curvature and presents deviations from the Abrikosov and
Gor'kov theory, a phenomenon already supported by experimental evidence.",1606.07051v3
2016-06-30,The Lorentz Group with Dual-Translations and the Conformal Group,"For those finite-matrix representations of the Lorentz group of
rotations/boosts with spin $(A,B)\oplus(C,D)$ that can also represent
translations, two possible translation subgroups qualify. Of these two, one
must be selected, and one discarded, to represent the Poincar\'{e} group of
rotations/boosts with translations in spacetime. Instead, let us discard the
requirement that there be just one translation subgroup. With
dual-translations, one gives up agreement with simple macroscopic observations
of spacetime. Now the transformations of both possible translation subgroups
combine with those of the Lorentz group. The resulting commutation relations
require new transformations and generators to satisfy the linearity requirement
of a Lie algebra. Special cases of spins are sought to restrict the influx of
new transformations. One finds that the Dirac 4-spinor formalism is the only
viable solution. The slightly expanded group it represents is the conformal
group with just one new transformation, scale change. It follows as a corollary
that the Dirac 4-spinor formalism is the only matrix representation of the
conformal group with spin $(A,B)\oplus(C,D).$",1607.01250v2
2016-07-11,Some Features of Scattering Problem in a $κ$-Deformed Minkowski Spacetime,"The doubly special relativity (DSR) theories are suggested in order to
incorporate an observer-independent length scale in special theory of
relativity. The Magueijo-Smolin proposal of DSR is realizable through a
particular form of the noncommutative (NC) spacetime (known as
$\kappa$-Minkowski spacetime) in which the Lorentz symmetry is preserved. In
this framework, the NC parameter $\kappa$ provides the origin of natural cutoff
energy scale. Using a nonlinear deformed relativistic dispersion relation along
with the Lorentz transformations, we investigate some phenomenological facets
of two-body collision problem (without creation of new particles) in a
$\kappa$-Minkowski spacetime. By treating an elastic scattering problem, we
study effects of the Planck scale energy cutoff on some relativistic
kinematical properties of this scattering problem. The results are challenging
in the sense that as soon as one turns on the $\kappa$-spacetime extension, the
nature of the two-body collision alters from elastic to inelastic one. It is
shown also that a significant kinematical variable involving in heavy ion
collisions, the rapidity, is not essentially an additive quantity under a
sequence of the nonlinear representation of the Lorentz transformations.",1607.02869v1
2016-07-12,Is there a signal for Lorentz non-invariance in existing radioactive decay data?,"Measurements of the beta decay rates of nuclei have revealed annual
periodicities with approximately the same relative amplitude even though the
half-lives range over nine orders of magnitude. Here we show that this can be
explained if the emitted neutrinos behave as if they propagate in a medium with
a refractive index which varies as the Earth orbits the sun. This refractive
index may be due to fundamental Lorentz non-invariance (LNI), or apparent LNI
arising from interactions with solar or relic neutrinos, or dark matter.
Additionally, this medium could have consequences for experiments attempting to
measure the neutrino mass.",1607.03541v2
2016-07-18,Gauge field spectrum in massive Yang-Mills theory with Lorentz violation,"The spectrum of the massive CPT-odd Yang-Mills propagator with Lorentz
violation is performed at tree-level. The modification is due to mass terms
generated by the exigence of multiplicative renormalizability of Yang-Mills
theory with Lorentz violation. The causality analysis is performed from group
and front velocities for both, spacelike and timelike background tensors. It is
show that, by demanding causality, it is always possible to define a physical
sector for the gauge propagator. Hence, it is expected that the model is also
unitary, if one takes the Faddeev-Popov ghost into account.",1607.05261v2
2016-07-21,Classical Nonminimal Lagrangians and Kinematic Tests of Special Relativity,"This article gives a brief summary on recently obtained classical lagrangians
for the nonminimal fermion sector of the Standard-Model Extension (SME). Such
lagrangians are adequate descriptions of classical particles that are subject
to a Lorentz-violating background field based on the SME. Explicitly,
lagrangians were obtained for the leading nonminimal contributions of the m, a,
c, e, and f coefficients. These results were then used to interpret classical,
kinematic tests of Special Relativity in the framework of the nonminimal SME.
This led to new constraints on certain nonminimal controlling coefficients.
Although the experiments were very sophisticated in the era when they were
carried out, their sensitivities for detecting Lorentz violation were still far
away from the Planck scale. Obtaining the novel constraints can be considered
as a proof-of-principle demonstrating the applicability of the classical
lagrangians computed.",1607.06323v1
2016-07-22,Limit on Lorentz-Invariance- and CPT-Violating Neutron Spin Interactions Using a $^3$He-$^{129}$Xe Comagnetometer,"We performed a search for a Lorentz-invariance- and CPT-violating coupling of
the $^3$He and $^{129}$Xe nuclear spins to posited background fields. Our
experimental approach is to measure the free precession of nuclear spin
polarized $^3$He and $^{129}$Xe atoms using SQUID detectors. As the laboratory
reference frame rotates with respect to distant stars, we look for a sidereal
modulation of the Larmor frequencies of the co-located spin samples. As a
result we obtain an upper limit on the equatorial component of the background
field $\tilde{b}^n_{\bot}< 8.4 \cdot 10^{-34}$ GeV (68\% C.L.). Furthermore,
this technique was modified to search for an electric dipole moment (EDM) of
$^{129}$Xe.",1607.06719v1
2016-07-29,Massive photons from Super and Lorentz symmetry breaking,"In the context of Standard Model Extensions (SMEs), we analyse four general
classes of Super Symmetry (SuSy) and Lorentz Symmetry (LoSy) breaking, leading
to {observable} imprints at our energy scales. The photon dispersion relations
show a non-Maxwellian behaviour for the CPT (Charge-Parity-Time reversal
symmetry) odd and even sectors. The group velocities exhibit also a directional
dependence with respect to the breaking background vector (odd CPT) or tensor
(even CPT). In the former sector, the group velocity may decay following an
inverse squared frequency behaviour. Thus, we extract a massive and gauge
invariant Carroll-Field-Jackiw photon term in the Lagrangian and show that the
mass is proportional to the breaking vector. The latter is estimated by ground
measurements and leads to a photon mass upper limit of $10^{-19}$ eV or $2
\times 10^{-55}$ kg and thereby to a potentially measurable delay at low radio
frequencies.",1607.08786v1
2016-09-05,Reconfinement of highly magnetized jets: Implications for HST-1 in M87,"Stationary features are occasionally observed in AGN jets. A notable example
is the HST-1 knot in M87. Such features are commonly interpreted as
re-confinement shocks in hydrodynamic jets or focusing nozzles in Poynting
jets. In this paper we compute the structure and Lorentz factor of a highly
magnetized jet confined by external pressure having a profile that flattens
abruptly at some radius. We find the development of strong oscillations upon
transition from the steeper to the flatter pressure profile medium. Analytic
formula is derived for the location of the nodes of these oscillations. We
apply the model to the M87 jet and show that if the jet remains magnetically
dominated up to sub-kpc scales, then focusing is expected. The location of the
HST-1 knot can be reconciled with recent measurements of the pressure profile
around the Bondi radius if the jet luminosity satisfies $L_j\simeq10^{43}$
erg/s. However, we find that magnetic domination at the collimation break
implies a Lorentz factor in excess of $10^2$, atypical to FRI sources. A much
lower value of the asymptotic Lorentz factor would require substantial loading
close to the black hole. In that case HST-1 may be associated with a
collimation nozzle of a hydrodynamic flow.",1609.01091v1
2016-09-12,A conformal model of gravitons,"In the description of general covariance, the vierbein and the Lorentz
connection can be treated as independent fundamental fields. With the usual
gauge Lagrangian, the Lorentz connection is characterized by an asymptotically
free running coupling. When running from high energy, the coupling gets large
at a scale which can be called the Planck mass. If the Lorentz connection is
confined at that scale, the low energy theory can have the Einstein Lagrangian
induced at low energy through dimensional transmutation. However, in general
there will be new divergences in such a theory and the Lagrangian basis should
be expanded. I construct a conformally invariant model with a larger basis size
which potentially may have the same property.",1609.03524v2
2016-09-16,Inflation with teleparallelism: Can torsion generate primordial fluctuations without local Lorentz symmetry?,"Arbitrary generalization to the teleparallel equivalent of general relativity
loses local Lorentz invariance to reparametrize the orthonormal coordinate
system and gives rise to asymmetry field equations. We investigate consequences
of local Lorentz violation to primordial fluctuations in extended single field
inflationary models based on the scalar-tensor formulation of the torsion
scalar $T$ that effectively includes $f(T)$ gravity as a special case. We show
that despite some asymmetry part of the field equations are removed in a
spatially homogeneous and isotropic cosmic background, no subhorizon
scalar-perturbation mode can survive by the time of horizon crossing. As a
result, any scalar field mediated in torsion cannot generate enough primordial
density inhomogeneity alone, even if it brings some de Sitter background
solutions in generalized teleparallel gravity.",1609.04959v1
2016-09-19,Exact Finite-Difference Time-Domain Modelling of Broadband Huygens' Metasurfaces with Lorentz Dispersions,"An explicit time-domain finite-difference technique for modelling
zero-thickness Huygens' metasurfaces based on Generalized Sheet Transition
Conditions (GSTCs), is proposed and demonstrated using full-wave simulations.
The Huygens' metasurface is modelled using electric and magnetic surface
susceptibilities, which are found to follow a double-Lorentz dispersion
profile. To solve zero-thickness Huygens' metasurface problems for general
broadband excitations, the double-Lorentz dispersion profile is combined with
GSTCs, leading to a set of first-order differential fields equations in
time-domain. Identifying the exact equivalence between Huygens' metasurfaces
and coupled RLC oscillator circuits, the field equations are then subsequently
solved using standard circuit modelling techniques based on a finite-difference
formulation. Several examples including generalized refraction are shown to
illustrate the temporal evolution of scattered fields from the Huygens'
metasurface under plane-wave normal incidence, in both harmonic steady-state
and broadband regimes. In particular, due to its inherent time-domain
formulation, a significant strength of the methodology is its ability to model
time-varying metasurfaces, which is demonstrated with a simple example of a
pumped metasurface leading to new frequency generation and wave amplification.",1609.05575v1
2016-09-27,Lorentz symmetry violation in the fermion number anomaly with the chiral overlap operator,"Recently, Grabowska and Kaplan proposed a four-dimensional lattice
formulation of chiral gauge theories on the basis of a chiral overlap operator.
We compute the classical continuum limit of the fermion number anomaly in this
formulation. Unexpectedly, we find that the continuum limit contains a term
which is not Lorentz invariant. The term is, however, proportional to the gauge
anomaly coefficient, and thus the fermion number anomaly in this lattice
formulation automatically restores the Lorentz-invariant form when and only
when the anomaly cancellation condition is met.",1609.08376v3
2016-10-14,Special Relativity: Scientific or Philosophical Theory?,"In this article, we argue that the theory of special relativity, as
formulated by Einstein, is a philosophical rather than a scientific theory.
What is scientific and experimentally supported is the formalism of the
relativistic mechanics embedded in the Lorentz transformations and their direct
mathematical, experimental and observational consequences. This is in parallel
with the quantum mechanics where the scientific content and experimental
support of this branch of physics is embedded in the formalism of quantum
mechanics and not in its philosophical interpretations such as the Copenhagen
school or the parallel worlds explanations. Einstein theory of special
relativity gets unduly credit from the success of the relativistic mechanics of
Lorentz transformations. Hence, all the postulates and consequences of Einstein
interpretation which have no direct experimental or observational support
should be reexamined and the relativistic mechanics of Lorentz transformations
should be treated in education, academia and research in a similar fashion to
that of quantum mechanics.",1610.05640v1
2016-10-21,Noncommutative Spaces and Poincaré Symmetry,"We present a framework which unifies a large class of non-commutative
spacetimes that can be described in terms of a deformed Heisenberg algebra. The
commutation relations between spacetime coordinates are up to linear order in
the coordinates, with structure constants depending on the momenta plus terms
depending only on the momenta. The possible implementations of the action of
Lorentz transformations on these deformed phase spaces are considered, together
with the consistency requirements they introduce. It is found that Lorentz
transformations in general act nontrivially on tensor products of momenta. In
particular the Lorentz group element which acts on the left and on the right of
a composition of two momenta is different, and depends on the momenta involved
in the process. We conclude with two representative examples, which illustrate
the mentioned effect.",1610.06716v2
2016-10-25,Constraints on the bulk Lorentz factor of Gamma-Ray Burst jets from Fermi/LAT upper limits,"It is largely recognized that Gamma-Ray Burst (GRB) jets involve
ultra-relativistic motion. However, the value of the Lorentz factor Gamma_0 is
still not clear and only lower limits are known for most bursts. We suggest
here a new method to obtain upper limits on Gamma_0. The early high-energy
synchrotron afterglow flux depends strongly on Gamma_0. Upper limits on GeV
emission therefore provide uppers limit on Gamma_0. Applying this method to 190
Fermi GRBs that have not been detected by the Fermi-LAT we place upper limits
on the high-energy afterglow flux, and in turn on Gamma_0. For bursts at a
typical redshift z=2, we find values of the order of 200 (and above) for a
homogeneous density medium, and in the range 100-400 for a wind-like medium.
These upper limits are consistent with (and are very close to) lower limits and
direct estimates inferred using other methods, suggesting that the typical
Lorentz factors of GRB jets are of order a few hundred.",1610.08056v1
2016-10-26,Effects of the Lorentz invariance violation in Coulomb interaction in nuclei and atoms,"Anisotropy in the speed of light that has been constrained by
Michelson-Morley-type experiments also generates anisotropy in the Coulomb
interactions. This anisotropy can manifest itself as an energy anisotropy in
nuclear and atomic experiments. Here the experimental limits on Lorentz
violation in 21Ne are used to improve the limits on the Lorentz symmetry in the
photon sector, namely the anisotropy of the speed of light and the Coulomb
interactions, by 7 orders of magnitude in comparison with previous experiments:
the speed of light is isotropic to a part in E-28.",1610.08188v3
2016-10-25,Problems and Progress in Covariant High Spin Description,"A universal description of particles with spins j greater or equal one ,
transforming in (j,0)+(0,j), is developed by means of representation specific
second order differential wave equations without auxiliary conditions and in
covariant bases such as Lorentz tensors for bosons, Lorentz-tensors with Dirac
spinor components for fermions, or, within the basis of the more fundamental
Weyl-Van-der-Waerden sl(2,C) spinor-tensors. At the root of the method, which
is free from the pathologies suffered by the traditional approaches, are
projectors constructed from the Casimir invariants of the spin-Lorentz group,
and the group of translations in the Minkowski space time.",1610.09219v1
2017-02-17,Global Lorentz estimates for nonlinear parabolic equations on nonsmooth domains,"Consider the nonlinear parabolic equation in the form $$ u_t-{\rm div}
\mathbf{a}(D u,x,t)={\rm div}\,(|F|^{p-2}F) \quad \text{in} \quad
\Omega\times(0,T), $$ where $T>0$ and $\Omega$ is a Reifenberg domain. We
suppose that the nonlinearity $\mathbf{a}(\xi,x,t)$ has a small BMO norm with
respect to $x$ and is merely measurable and bounded with respect to the time
variable $t$. In this paper, we prove the global Calder\'on-Zygmund estimates
for the weak solution to this parabolic problem in the setting of Lorentz
spaces which includes the estimates in Lebesgue spaces. Our global
Calder\'on-Zygmund estimates extend certain previous results to equations with
less regularity assumptions on the nonlinearity $\mathbf{a}(\xi,x,t)$ and to
more general setting of Lorentz spaces.",1702.06202v1
2017-02-24,Testing Lorentz invariance of dark matter with satellite galaxies,"We develop the framework for testing Lorentz invariance in the dark matter
sector using galactic dynamics. We consider a Lorentz violating (LV) vector
field acting on the dark matter component of a satellite galaxy orbiting in a
host halo. We introduce a numerical model for the dynamics of satellites in a
galactic halo and for a galaxy in a rich cluster to explore observational
consequences of such an LV field. The orbital motion of a satellite excites a
time dependent LV force which greatly affects its internal dynamics. Our
analysis points out key observational signatures which serve as probes of LV
forces. These include modifications to the line of sight velocity dispersion,
mass profiles and shapes of satellites. With future data and a more detailed
modeling these signatures can be exploited to constrain a new region of the
parameter space describing the LV in the dark matter sector.",1702.07726v2
2017-08-09,Localization in the Rindler Wedge,"One of the striking features of QED is that charged particles create a
coherent cloud of photons. The resultant coherent state vectors of photons
generate a non-trivial representation of the localized algebra of observables
that do not support a representation of the Lorentz group: Lorentz symmetry is
spontaneously broken. We show in particular that Lorentz boost generators
diverge in this representation, a result shown also in [1] (See also [2]).
Localization of observables, for example in the Rindler wedge, uses Poincar\'e
invariance in an essential way [3]. Hence in the presence of charged fields,
the photon observables cannot be localized in the Rindler wedge.
  These observations may have a bearing on the black hole information loss
paradox, as the physics in the exterior of the black hole has points of
resemblance to that in the Rindler wedge.",1708.02803v1
2017-08-10,Potential constrains on Lorentz invariance violation from the HAWC TeV gamma-rays,"Astrophysical scenarios provide a unique opportunity to test the possible
signatures of Lorentz Invariance Violation (LIV) due to the high energies and
the very long distances they involve. An isotropic correction to the photon
dispersion relation, by hypothetical Lorentz invariance violation, has a
consequence that photons of sufficient energy are unstable and decay very fast.
The High Altitude Water Cherenkov (HAWC) observatory is sensitive to gamma-rays
in the 100 GeV to 100 TeV energy range, making it a very useful tool to study
LIV. In this work we present potential stringent limits for the LIV energy
scale at first and second order correction by the potential observations of
primary very high energy photons in HAWC energy range.",1708.03384v1
2018-02-03,Mass - radius ratio bounds for compact objects in Lorentz-violating dRGT Massive Gravity theory,"We consider the mass-radius bounds for spherically symmetric static compact
objects in the de Rham-Gabadadze-Tolley (dRGT) Massive Gravity theories, free
of ghosts. In this type of gravitational theories the graviton, the quantum of
gravity, may have a small, but non-vanishing mass. We derive the hydrostatic
equilibrium and mass continuity equations in the Lorentz-violating Massive
gravity in the presence of a cosmological constant and for a non-zero graviton
mass. The case of the constant density stars is also investigated by
numerically solving the equilibrium equations. The influence of the graviton
mass on the global parameters (mass and radius) of these stellar configurations
is also considered. The generalized Buchdahl relations, giving the upper and
lower bounds of the mass-radius ratio are obtained, and discussed in detail. As
an application of our results we obtain gravitational redshift bounds for
compact stellar type objects in the Lorentz-violating dRGT Massive Gravity,
which may (at least in principle) be used for observationally testing this
theory in an astrophysical context.",1802.01017v2
2018-02-13,Motion of a Rigid Body in a Special Lorentz Gas: Loss of Memory Effect,"Linear motion of a rigid body in a special kind of Lorentz gas is
mathematically analyzed. The rigid body moves against gas drag according to
Newton's equation. The gas model is a special Lorentz gas consisting of gas
molecules and background obstacles, which was introduced in~(Tsuji and Aoki: J.
Stat. Phys. \textbf{146}, 620--645, 2012). The specular boundary condition is
imposed on the resulting kinetic equation. This study complements the numerical
study by Tsuji and Aoki cited above --- although the setting in this paper is
slightly different from theirs, qualitatively the same asymptotic behavior is
proved: The velocity $V(t)$ of the rigid body decays exponentially if the
obstacles undergo thermal motion; if the obstacles are motionless, then the
velocity $V(t)$ decays algebraically with a rate $t^{-5}$ independent of the
spatial dimension. This demonstrates the idea that interaction of the molecules
with the background obstacles destroy the memory effect due to recollision.",1802.04414v1
2018-04-11,A MAD Explanation for the Correlation between Bulk Lorentz Factor and Minimum Variability Timescale,"We offer an explanation for the anti-correlation between the minimum
variability timescale ($MTS$) in the prompt emission light curve of gamma-ray
bursts (GRBs) and the estimated bulk Lorentz factor of these GRBs, in the
context of a magnetically arrested disk (MAD) model. In particular, we show
that previously derived limits on the maximum available energy per baryon in a
Blandford-Znajek jet leads to a relationship between the characteristic MAD
timescale, $t_{MAD}$, in GRBs and the maximum bulk Lorentz factor: $t_{MAD}
\propto \Gamma^{-6}$, somewhat steeper than (although within the error bars of)
the fitted relationship found in the GRB data. Similarly, the MAD model also
naturally accounts for the observed anti-correlation between $MTS$ and
gamma-ray luminosity $L$ in the GRB data, and we estimate the accretion rates
of the GRB disks (given these luminosities) in the context of this model. Both
of these correlations ($MTS-\Gamma$ and $MTS-L$) are also observed in the AGN
data, and we discuss the implications of our results in the context of both GRB
and blazar systems.",1804.04194v1
2018-04-23,On quantum aspects of the higher-derivative Lorentz-breaking extension of QED,"We consider the higher-derivative Lorentz-breaking extension of QED, where
the new terms are the Myers-Pospelov-like ones in gauge and spinor sectors, and
the higher--derivative CFJ term. For this theory, we study its tree-level
dynamics, discuss the dispersion relation, and present one more scheme for its
perturbative generation, including the finite temperature case. Also, we
develop a method to study perturbative unitarity based on consistent rotation
of the theory to Euclidean space. We use this method to verify explicitly that
for special choices of the Lorentz-breaking vector, the unitarity is preserved
at the one-loop level, even in the presence of higher time derivatives.",1804.08413v3
2020-06-30,Mean propagation velocity of multiphoton wave-packet states with nonzero Lorentz-invariant mass,"The concept of Lorenz invariant mass and mean propagation velocity have been
investigated in detail for various multiphoton wave-packet states of light.
Based on photodetection theory and straightforward kinematics, we presented a
physically reasonable and at the same time rigorous proof that mean propagation
velocity is consistent with the Lorentz-invariant mass concept for an arbitrary
multiphoton wave-packet state. We argued that mean propagation velocity is less
than the speed of light constant in vacuum and is governed by geometric
properties of state's amplitude in wave-vector space for arbitrary wave-packet
states. To classify states with different fixed values of Lorentz-invariant
mass, we introduced a specific set of modes that allow us to describe the
wave-packet state in its rest frame.",2007.00447v1
2020-07-06,Fermionic dualities with axial gauge fields,"The dualities that map hard-to-solve, interacting theories to free,
non-interacting ones often trigger a deeper understanding of the systems to
which they apply. However, simplifying assumptions such as Lorentz invariance,
low dimensionality, or the absence of axial gauge fields, limit their
application to a broad class of systems, including topological semimetals. Here
we derive several axial field theory dualities in 2+1 and 3+1 dimensions by
developing an axial slave-rotor approach capable of accounting for the axial
anomaly. Our 2+1-dimensional duality suggests the existence of a dual, critical
surface theory for strained three-dimensional non-symmorphic topological
insulators. Our 3+1-dimensional duality maps free Dirac fermions to Dirac
fermions coupled to emergent U(1) and Kalb-Ramond vector and axial gauge
fields. Upon fixing an axial field configuration that breaks Lorentz
invariance, this duality maps free to interacting Weyl semimetals, thereby
suggesting that the quantization of the non-linear circular photogalvanic
effect can be robust to certain interactions. Our work emphasizes how axial and
Lorentz-breaking dualities improve our understanding of topological matter.",2007.02944v2
2020-07-08,Correlations in multithermostat Brownian systems with Lorentz force,"We study the motion of a Brownian particle subjected to Lorentz force due to
an external magnetic field. Each spatial degree of freedom of the particle is
coupled to a different thermostat. We show that the magnetic field results in
correlation between different velocity components in the stationary state.
Integrating the velocity autocorrelation matrix, we obtain the diffusion matrix
that enters the Fokker-Planck equation for the probability density. The
eigenvectors of the diffusion matrix do not align with the temperature axes. As
a consequence the Brownian particle performs spatially correlated diffusion. We
further show that in the presence of an isotropic confining potential, an
unusual, flux-free steady state emerges which is characterized by a
non-Boltzmann density distribution, which can be rotated by reversing the
magnetic field. The nontrivial steady state properties of our system result
from the Lorentz force induced coupling of the spatial degrees of freedom which
cease to exist in equilibrium corresponding to a single-temperature system.",2007.03967v2
2020-06-26,Condición de Lorentz y ecuaciones de ondas electromagnéticas como propiedades emergentes del sistema de Maxwell,"This article deals with the study of electromagnetic waves equations and the
Lorentz condition, as emergent properties of Maxwell's system in the context of
systems theory. To do this, the wave equations and the Helmholtz equation are
first deduced. Using the displaced Dirac operator, which is closely related to
the main vector calculation operators, it is possible to establish a direct
connection between the solutions of the Maxwell time-harmonic system and two
quaternion equations. Also, the application of the Lorentz condition to
transform the time-harmonic Maxwell system into a simple quaternion equation
based on the scalar and vector potentials is exposed.",2007.10285v2
2020-07-24,Proving the Relativistic Rotation Paradox,"An apparent paradox in Einstein's Special Theory of Relativity, known as a
Thomas precession rotation in atomic physics, has been verified experimentally
in a number of ways. However, somewhat surprisingly, it has not yet been
demonstrated algebraically in a straightforward manner using
Lorentz-matrix-algebra. Authors in the past have resorted instead to computer
verifications, or to overly-complicated derivations, leaving undergraduate
students in particular with the impression that this is a mysterious and
mathematically inaccessible phenomenon. This is surprising because, as shown in
the present note, it is possible to use a basic property of orthogonal Lorentz
matrices and a judicious choice for the configuration of the relevant inertial
frames to give a very transparent algebraic proof. It is pedagogically useful
for physics students particularly at undergraduate level to explore this. It
not only clarifies the nature of the paradox at an accessible mathematical
level and sheds additional light on some mathematical properties of Lorentz
matrices and relatively-moving frames. It also illustrates the satisfaction
that a clear mathematical understanding of a physics problem can bring,
compared to uninspired computations or tortured derivations.",2007.12686v2
2010-05-19,Is it possible to accommodate massive photons in the framework of a gauge-invariant electrodynamics?,"The construction of an alternative electromagnetic theory that preserves
Lorentz and gauge symmetries, is considered. We start off by building up
Maxwell electrodynamics in (3+1)D from the assumption that the associated
Lagrangian is a gauge-invariant functional that depends on the electron and
photon fields and their first derivatives only. In this scenario, as
well-known, it is not possible to set up a Lorentz invariant gauge theory
containing a massive photon. We show nevertheless that there exist two
radically different electrodynamics, namely, the Chern-Simons and the Podolsky
formulations, in which this problem can be overcome. The former is only valid
in odd space-time dimensions, while the latter requires the presence of
higher-order derivatives of the gauge field in the Lagrangian. This theory,
usually known as Podolsky electrodynamics, is simultaneously gauge and Lorentz
invariant; in addition, it contains a massive photon. Therefore, a massive
photon, unlike the popular belief, can be adequately accommodated within the
context of a gauge-invariant electrodynamics.",1005.3480v1
2013-08-01,Snyder Momentum Space in Relative Locality,"The standard approaches of phenomenology of Quantum Gravity have usually
explicitly violated Lorentz invariance, either in the dispersion relation or in
the addition rule for momenta. We investigate whether it is possible in 3+1
dimensions to have a non local deformation that preserves fully Lorentz
invariance, as it is the case in 2+1D Quantum Gravity. We answer positively to
this question and show for the first time how to construct a homogeneously
curved momentum space preserving the full action of the Lorentz group in
dimension 4 and higher, despite relaxing locality. We study the property of
this relative locality deformation and show that this space leads to a
noncommutativity related to Snyder spacetime.",1308.0300v2
2013-08-06,Charged lepton electric dipole moment enhancement in the Lorentz violated extension of the standard model,"We consider the Lorentz violated extension of the standard model. In this
framework, there are terms that explicitly violate CP-symmetry. We examine the
CPT-even $d_{\mu\nu}$-term to find the electric dipole moment of charged
leptons. We show that the form factors besides the momentum transfer, depend on
a new Lorentz-scalar, constructing by $d_{\mu\nu}$ and the four momenta of the
lepton, as well. Such an energy dependence of the electric dipole form factor
leads to an enhancement of the lepton electric dipole moment at high energy,
even at the zero momentum transfer. We show that at $\frac{|d|p^2}{m^2_l}\sim
1$ the electric dipole moment of the charged lepton can be as large as
$10^{-14} e\,\,cm$.",1308.1249v1
2013-08-09,"Aharonov-Bohm effect, local field interaction, and Lorentz invariance","A field-interaction scheme is introduced for describing the Aharonov-Bohm
effect, fully consistent with the principle of relativity. Our theory is based
on the fact that local field interactions are present even when a particle
moves only in a field-free region. The interaction Lagrangian between a charge
and a flux is uniquely constructed from three principles: Lorentz covariance,
linearity in the interaction strength, and a correct stationary limit of
charge. Our result resolves fundamental questions raised on the standard
interpretation of the Aharonov-Bohm effect, concerning its duality with the
Aharonov-Casher effect and the equivalence between the potential and the
field-interaction models for describing the electromagnetic interaction. Most
of all, potential is eliminated in our theory, and all kind of the force-free
Aharonov-Bohm effect is understood in a unified framework of the
Lorentz-covariant local interaction of electromagnetic fields.",1308.2093v5
2013-08-29,Natural curvature for manifest T-duality,"We reformulate the manifestly T-dual description of the massless sector of
the closed bosonic string, directly from the geometry associated with the (left
and right) affine Lie algebra of the coset space Poincare/Lorentz. This
construction initially doubles not only the (spacetime) coordinates for
translations but also those for Lorentz transformations (and their dual). As a
result, the Lorentz connection couples directly to the string (as does the
vielbein), rather than being introduced ad hoc to the covariant derivative as
previously. This not only reproduces the old definition of T-dual torsion, but
automatically gives a general, covariant definition of T-dual curvature (but
still with some undetermined connections).",1308.6350v3
2014-03-03,"Emergent Lorentz Signature, Fermions, and the Standard Model","This article investigates the construction of fermions and the formulation of
the Standard Model of particle physics in a theory in which the Lorentz
signature emerges from an underlying microscopic purely Euclidean $SO(4)$
theory. Couplings to a clock field are responsible for triggering the change of
signature of the effective metric in which the standard fields propagate. We
demonstrate that Weyl and Majorana fermions can be constructed in this
framework. This construction differs from other studies of Euclidean fermions,
as the coupling to the clock field allows us to write down an action which
flows to the usual action in Minkowski spacetime. We then show how the Standard
Model can be obtained in this theory and consider the constraints on
non-Standard-Model operators which can appear in the QED sector due to CPT and
Lorentz violation.",1403.0580v2
2016-11-23,Active Brownian particles moving in a random Lorentz gas,"Biological microswimmers often inhabit a porous or crowded environment such
as soil. In order to understand how such a complex environment influences their
spreading, we numerically study non-interacting active Brownian particles
(ABPs) in a two-dimensional random Lorentz gas. Close to the percolation
transition in the Lorentz gas, they perform the same subdiffusive motion as
ballistic and diffusive particles. However, due to their persistent motion they
reach their long-time dynamics faster than passive particles and also show
superdiffusive motion at intermediate times. While above the critical obstacle
density $\eta_c$ the ABPs are trapped, their long-time diffusion below $\eta_c$
is strongly influenced by the propulsion speed $v_0$. With increasing $v_0$,
ABPs are stuck at the obstacles for longer times. Thus, for large propulsion
speed, the long-time diffusion constant decreases more strongly in a denser
obstacle environment than for passive particles. This agrees with the behavior
of an effective swimming velocity and persistence time, which we extract from
the velocity autocorrelation function.",1611.07892v2
2016-11-25,On the PeV knee of cosmic rays spectrum and TeV cutoff of electron spectrum,"Spectra of Cosmic Rays (CRs), particularly their features, may hold essential
information about astroparticle and fundamental physics. Realizing that both
$4$ PeV CR knee and electron's TeV break have nearly identical Lorentz factor,
i.e. $\gamma \sim 10^6$, we propose that both CR nuclei and electron experience
a threshold interaction with unknown light particle $\rm X$, widespread in the
diffusive halo. The interaction occurs only when the Lorentz factor of CRs is
larger than $10^6$. Via this process, the energy spectrum of each component has
deformation above the threshold Lorentz factor, so both knee and spectral break
of electrons can be naturally reproduced. Given the large uncertainties of the
available measurements and simplified assumption, our model accommodates a wide
mass range of the particle X, which is allowable from ultralight value to $\sim
1$ eV.",1611.08384v3
2016-11-27,A Homogeneous and Isotropic Universe in Lorentz Gauge Theory of Gravity,"Lorentz gauge theory of gravity was recently introduced. We study the
homogeneous and isotropic universe of this theory. It is shown that some time
after the matter in the universe is diluted enough, at $z \sim 0.6$, the
decelerating expansion shifts spontaneously to an accelerating one without a
dark energy. We discuss that Lorentz gauge theory puts no constraint on the
total energy content of the universe at present time and therefore the
magnitude of vacuum energy predicted by field theory is not contradictory
anymore. It is demonstrated that in this theory the limit on the number of
relativistic particles in the universe is much looser than in GR. An
inflationary mechanism is discussed as well. We show that the theory, unlike
GR, does not require the slow-roll or similar conditions to drive the inflation
at the beginning of the universe.",1611.08909v2
2016-11-28,A test of local Lorentz invariance with Compton scattering asymmetry,"We report on a measurement of the constancy and anisotropy of the speed of
light relative to the electrons in photon-electron scattering. We used the
Compton scattering asymmetry measured by the new Compton polarimeter in Hall~C
at Jefferson Lab to test for deviations from unity of the vacuum refractive
index ($n$). For photon energies in the range of 9 - 46 MeV, we obtain a new
limit of $1-n < 1.4 \times 10^{-8}$. In addition, the absence of sidereal
variation over the six month period of the measurement constrains any
anisotropies in the speed of light. These constitute the first study of Lorentz
invariance using Compton asymmetry. Within the minimal standard model extension
framework, our result yield limits on the photon and electron coefficients
$\tilde{\kappa}_{0^+}^{YZ}, c_{TX}, \tilde{\kappa}_{0^+}^{ZX}$, and $c_{TY}$.
Although, these limits are several orders of magnitude larger than the current
best limits, they demonstrate the feasibility of using Compton asymmetry for
tests of Lorentz invariance. Future parity violating electron scattering
experiments at Jefferson Lab will use higher energy electrons enabling better
constraints.",1611.09173v1
2017-01-10,Lorentz invariance violation in the neutrino sector: a joint analysis from big bang nucleosynthesis and the cosmic microwave background,"We investigate constraints on Lorentz invariance violation in the neutrino
sector from a joint analysis of big bang nucleosynthesis and the cosmic
microwave background. The effect of Lorentz invariance violation during the
epoch of big bang nucleosynthesis changes the predicted helium-4 abundance,
which influences the power spectrum of the cosmic microwave background at the
recombination epoch. In combination with the latest measurement of the
primordial helium-4 abundance, the Planck 2015 data of the cosmic microwave
background anisotropies give a strong constraint on the deformation parameter
since adding the primordial helium measurement breaks the degeneracy between
the deformation parameter and the physical dark matter density.",1701.02553v2
2017-01-15,The Abraham-Lorentz force and electrodynamics at the classical electron radius,"The Abraham-Lorentz force is a finite remnant of the UV singular structure of
the self interaction of a point charge with its own field. The satisfactory
description of such interaction needs a relativistic regulator. This turns out
to be a problematic point because the energy of regulated relativistic cutoff
theories is unbounded from below. However one can construct point splitting
regulators which keep the Abraham-Lorentz force stable. The classical language
can be reconciled with QED by pointing out that the effective quantum theory
for the electric charge supports a saddle point producing the classical
radiation reaction forces.",1701.04068v4
2017-01-20,Lorentz invariance violation as an explanation of muon excess in Auger data,"The Auger collaboration has observed the number of muons which is higher than
its prediction by existing hadronic interaction models. We explain this excess
of muons by using Lorentz invariance violation (LIV) in photon sector. As an
outcome of Lorentz invariance violation, the dispersion relation of photon gets
modified, which we use for the calculation of $\pi^0$ decay width. In the Auger
data of primary energy $10^{9.8}<E(\mbox{GeV})<10^{10.2}$, we find that the
neutral pion decay width is suppressed in comparison to its standard model (SM)
counterpart. As a result, we get a large number of muons explaining the
observed muon excess. We consider Planck suppressed LIV at order
$\mathcal{O}(p^2/M^2_{\tiny \mbox{Pl}})$ for studying the photon sector, which
is in agreement with the current bounds, and not as tightly constrained as LIV
at order $\mathcal{O}(p/M_{\tiny \mbox{Pl}})$.",1701.05890v2
2017-04-28,"Time Isotropy, Lorentz Transformation and Inertial Frames","Homogeneity of space and time, spatial isotropy, principle of relativity and
the existence of a finite speed limit (or its variants) are commonly believed
to be the only axioms required for developing the special theory of relativity
(Lorentz transformations). In this paper it is shown, however, that Lorentz
transformation cannot actually be derived without the explicit assumption of
time isotropy (time-reversal symmetry) which is logically independent of the
other postulates of relativity. Postulating time isotropy also restores the
symmetry between space and time in the postulates of relativity. Inertial
frames are defined in influential texts as frames having space-time homogeneity
and spatial isotropy only. Inclusion of time isotropy in that definition is
also suggested.",1704.08840v2
2018-05-15,Superfluids and the Cosmological Constant Problem,"We introduce a novel method to circumvent Weinberg's no-go theorem for
self-tuning the cosmological vacuum energy: a Lorentz-violating
finite-temperature superfluid can counter the effects of an arbitrarily large
cosmological constant. Fluctuations of the superfluid result in the graviton
acquiring a Lorentz-violating mass and we identify a unique class of theories
that are pathology free, phenomenologically viable, and do not suffer from
instantaneous modes. This new and hitherto unidentified phase of massive
gravity propagates the same degrees of freedom as general relativity with an
additional Lorentz-violating scalar that is introduced by higher-derivative
operators in a UV insensitive manner. The superfluid is therefore a consistent
infrared modification of gravity. We demonstrate how the superfluid can
degravitate a cosmological constant and discuss its phenomenology.",1805.05937v1
2018-05-29,Lorentz violation and the electron-ion collider,"We investigate the prospects for detecting violations of Lorentz symmetry in
unpolarized deep inelastic electron-proton scattering in the context of the
future electron-ion collider. Simulated differential cross-section data are
used to place expected bounds on a class of quark-sector coefficients for
Lorentz violation that induce sidereal time dependence in the scattering cross
section. We find that, with $100 \; {\rm fb}^{-1}$ of integrated luminosity,
the expected bounds are in the $10^{-5}-10^{-7}$ range and are roughly two
orders of magnitude stronger than those that can be extracted from existing
HERA data. We also discuss the possibility of extracting bounds on the
remaining time-independent coefficients.",1805.11684v3
2008-07-14,UHECR bounds on Lorentz violation in the photon sector,"The aim of this brief review is to present a case study of how astrophysics
data can be used to get bounds on Lorentz-violating parameters. For this
purpose, a particularly simple Lorentz-violating modification of the Maxwell
theory of photons is considered, which maintains gauge invariance, CPT, and
renormalization. With a standard spin-one-half Dirac particle minimally coupled
to this nonstandard photon, the resulting modified-quantum-electrodynamics
model involves nineteen dimensionless ""deformation parameters."" Ten of these
parameters lead to birefringence and are already tightly constrained by
astrophysics. New bounds on the remaining nine nonbirefringent parameters have
been obtained from the inferred absence of vacuum Cherenkov radiation in
ultrahigh-energy-cosmic-ray (UHECR) events. The resulting astrophysics bounds
improve considerably upon current laboratory bounds and the implications of
this ""null experiment"" may be profound, both for elementary particle physics
and cosmology.",0807.2147v4
2008-07-22,The Heisenberg-Lorentz quantum group,"In this article we present a new C*-algebraic deformation of the Lorentz
group. It is obtained by means of the Rieffel deformation applied to SL(2,C).
We give a detailed description of the resulting quantum group in terms of
generators - the quantum counterparts of the matrix coefficients of the
fundamental representation of SL(2,C). In order to construct the most involved
of four generators, we first define it on the quantum Borel subgroup, then on
the quantum complement of the Borel subgroup and finally we perform the gluing
procedure. In order to classify representations of the C*-algebra of the
Heisenberg-Lorentz quantum group and to analyze the action of the
comultiplication on the generators we employ the duality in the theory of
locally compact quantum groups.",0807.3401v4
2008-07-28,Discussing Cosmic String Configurations in a Supersymmetric Scenario without Lorentz Invariance,"The main goal of this work is to pursue an investigation of cosmic string
configurations focusing on possible consequences of the Lorentz-symmetry
breaking by a background vector. We analyze the possibility of cosmic strings
as a viable source for fermionic Cold Dark Matter particles. Whenever the
latter are charged and have mass of the order of $10^{13}GeV$, we propose they
could decay into usual cosmic rays. We have also contemplated the sector of
neutral particles generated in our model. Indeed, being neutral, these
particles are hard to be detected; however, by virtue of the Lorentz-symmetry
breaking background vector, it is possible that they may present an
electromagnetic interaction with a significant magnetic moment.",0807.4342v4
2009-12-02,Gamma-ray and Cosmic-ray Tests of Lorentz Invariance Violation and Quantum Gravity Models and Their Implications,"The topic of Lorentz invariance violation is a fundamental question in
physics that has taken on particular interest in theoretical explorations of
quantum gravity scenarios. I discuss various gamma-ray observations that give
limits on predicted potential effects of Lorentz invariance violation. Among
these are spectral data from ground based observations of the multi-TeV
gamma-rays from nearby AGN, INTEGRAL detections of polarized soft gamma-rays
from the vicinity of the Crab pulsar, Fermi Gamma Ray Space Telescope studies
of photon propagation timing from gamma-ray bursts, and Auger data on the
spectrum of ultrahigh energy cosmic rays. These results can be used to
seriously constrain or rule out some models involving Planck scale physics.
Possible implications of these limits for quantum gravity and Planck scale
physics will be discussed.",0912.0500v2
2009-12-22,Lorentz and CPT violation in QED revisited: A missing analysis,"We investigate the breakdown of Lorentz symmetry in QED by a CPT violating
interaction term consisting of the coupling of an axial fermion current with a
constant vector field $b$, in the framework of algebraic renormalization -- a
regularization-independent method. We show, to all orders in perturbation
theory, that a CPT-odd and Lorentz violating Chern-Simons-like term,
definitively, is not radiatively induced by the axial coupling of the fermions
with the constant vector $b$.",0912.4392v2
2009-12-22,Relativistic Model for Gravity-Induced Quantum State Reduction,"A Lorentz invariant model for gravity-induced quantum state reduction is
presented, which is mainly developed from Penrose's argument that the time
translation operator in a superposition of macroscopic states is ill-defined.
The problem to define a Lorentz invariant stochastic dynamics for the
wave-function is solved by assuming that the stochastic time flow is running
orthogonal to the deterministic, unitary time evolution inside the
four-dimensional space-time, which makes the direction of causality independent
from the chosen reference frame. This new view allows to accept Bell's position
on the implication of quantum non-locality on relativity, without having to
give up the Lorentz invariance of the specified dynamics. It is shown that it
is possible to formulate on the basis of this new view a meaningful physical
model. The model is also checked for possible higher order effects, which
provide new starting points for experimental research.",0912.4409v3
2011-11-04,Consistency analysis of a nonbirefringent Lorentz-violating planar model,"In this work analyze the physical consistency of a nonbirefringent
Lorentz-violating planar model via the analysis of the pole structure of its
Feynman propagators. The nonbirefringent planar model, obtained from the
dimensional reduction of the CPT-even gauge sector of the standard model
extension, is composed of a gauge and a scalar fields, being affected by
Lorentz-violating (LIV) coefficients encoded in the symmetric tensor
$\kappa_{\mu\nu}$. The propagator of the gauge field is explicitly evaluated
and expressed in terms of linear independent symmetric tensors, presenting only
one physical mode. The same holds for the scalar propagator. A consistency
analysis is performed based on the poles of the propagators. The isotropic
parity-even sector is stable, causal and unitary mode for $0\leq\kappa_{00}<1$.
On the other hand, the anisotropic sector is stable and unitary but in general
noncausal. Finally, it is shown that this planar model interacting with a
$\lambda|\varphi|^{4}-$Higgs field supports compactlike vortex configurations.",1111.1222v3
2011-11-07,Lifshitz scalar fields: one loop renormalization in curved backgrounds,"We consider an interacting Lifshitz field with z=3 in a curved spacetime. We
analyze the renormalizability of the theory for interactions of the form lambda
phi^n, with arbitrary even n. We compute the running of the coupling constants
both in the ultraviolet and infrared regimes. We show that the Lorentz
violating terms generate couplings to the spacetime metric that are not
invariant under general coordinate transformations. These couplings are not
suppressed by the scale of Lorentz violation and therefore survive at low
energies. We point out that in these theories, unless the effective mass of the
field is many orders of magnitude below the scale of Lorentz violation, the
coupling to the four dimensional Ricci scalar xi (4)R phi^2 does not receive
large quantum corrections xi >> 1.",1111.1662v2
2011-11-15,Supersymmetrization Schemes of D=4 Maxwell Algebra,"The Maxwell algebra, an enlargement of Poincare algebra by Abelian tensorial
generators, can be obtained in arbitrary dimension D by the suitable
contraction of O(D-1,1) \oplus O(D-1,2) (Lorentz algebra \oplus AdS algebra).
We recall that in D=4 the Lorentz algebra O(3,1) is described by the
realification Sp_R(2|C) of complex algebra Sp(2|C)\simeq Sl(2|C) and
O(3,2)\simeq Sp(4). We study various D=4 N-extended Maxwell superalgebras
obtained by the contractions of real superalgebras OSp_R(2N-k; 2|C)\oplus
OSp(k;4), (k=1,2,...,2N) (extended Lorentz superalgebra \oplus extended AdS
superalgebra). If N=1 (k=1,2) one arrives at two different versions of simple
Maxwell superalgebra. For any fixed N we get 2N different superextensions of
Maxwell algebra with n-extended Poincare superalgebras (1\leq n \leq N) and the
internal symmetry sectors obtained by suitable contractions of the real algebra
O_R(2N-k|C)\oplus O(k). Finally the comments on possible applications of
Maxwell superalgebras are presented.",1111.3598v1
2011-11-18,Impossibility of superluminal travel in Lorentz violating theories,"Warp drives are space-times allowing for superluminal travel. However, they
are quantum mechanically unstable because they produce a Hawking-like radiation
which is blue shifted at their front wall without any bound. We reexamine this
instability when local Lorentz invariance is violated at ultrahigh energy by
dispersion, as in some theories of quantum gravity. Interestingly, even though
the ultraviolet divergence is now regulated, warp drives are still unstable.
Moreover the type of instability is different whether one uses a subluminal or
a superluminal dispersion relation. In the first case, a black-hole laser
yields an exponential amplification of the emitted flux whereas, in the second,
infrared effects produce a linear growth of that flux. These results suggest
that chronology could still be protected when violating Lorentz invariance.",1111.4356v2
2011-11-30,Cosmological Perturbations from a Group Theoretical Point of View,"We present a new approach to cosmological perturbations based on the theory
of Lie groups and their representations. After re-deriving the standard
covariant formalism from SO(3) considerations, we provide a new expansion of
the perturbed Friedmann-Lemaitre-Robertson-Walker (FLRW) metric in terms of
irreducible representations of the Lorentz group. The resulting decomposition
splits into (scalar, scalar), (scalar, vector) and (vector, vector) terms.
These equations directly correspond to the standard Lifshitz classification of
cosmological perturbations using scalar, vector and tensor modes which arise
from the irreducible SO(3) representation of the spatial part of the metric.
While the Lorentz group basis matches the underlying local symmetries of the
FLRW spacetime better than the SO(3), the new equations do not provide further
simplification compared to the standard cosmological perturbation theory. We
conjecture that this is due to the fact that the so(3,1) ~ su(2) x su(2)
Lorentz algebra has no pair of commuting generators commuting with any of the
translation group generators.",1111.7027v1
2012-01-16,Disordered locality and Lorentz dispersion relations: an explicit model of quantum foam,"Using the framework of Quantum Graphity, we construct an explicit model of a
quantum foam, a quantum spacetime with spatial non-local links. The states
depend on two parameters: the minimal size of the link and their density with
respect to this length. Macroscopic Lorentz invariance requires that the
quantum superposition of spacetimes is suppressed by the length of these
non-local links. We parametrize this suppression by the distribution of
non-local links lengths in the quantum foam. We discuss the general case and
then analyze two specific natural distributions. Corrections to the Lorentz
dispersion relations are calculated using techniques developed in previous
work.",1201.3206v3
2012-01-27,Klein-Gordon equation from Maxwell-Lorentz dynamics,"We consider Maxwell-Lorentz dynamics: that is to say, Newton's law under the
action of a Lorentz's force which obeys the Maxwell equations. A natural class
of solutions are those given by the Lagrangian submanifolds of the phase space
when it is endowed with the symplectic structure modified by the
electromagnetic field. We have found that the existence of this type of
solution leads us directly to the Klein-Gordon equation as a compatibility
condition. Therefore, surprisingly, quite natural assumptions on the classical
theory involve a quantum condition without any process of limit. This result
could be a partial response to the inquiries of Dirac.",1201.5685v2
2012-04-25,On calculation of cross sections in Lorentz violating theories,"We develop a systematic approach to the calculation of scattering cross
sections in theories with violation of the Lorentz invariance taking into
account the whole information about the theory Lagrangian. As an illustration
we derive the Feynman rules and formulas for sums over polarizations in spinor
electrodynamics with Lorentz violating operators of dimensions four and six.
These rules are applied to compute the probabilities of several astrophysically
relevant processes. We calculate the rates of photon decay and vacuum Cherenkov
radiation along with the cross sections of electron-positron pair production on
background radiation and in the Coulomb field. The latter process is essential
for detection of photon-induced air showers in the atmosphere.",1204.5782v1
2013-09-25,Limits on violations of Lorentz Symmetry from Gravity Probe B,"Generic violations of Lorentz symmetry can be described by an effective field
theory framework that contains both general relativity and the standard model
of particle physics called the Standard-Model Extension (SME). We obtain new
constraints on the gravitational sector of the SME using recently published
final results from Gravity Probe B. These include for the first time an upper
limit at the 10^(-3) level on the time-time component of the new tensor field
responsible for inducing local Lorentz violation in the theory, and an
independent limit at the 10^(-7) level on a combination of components of this
tensor field.",1309.6399v1
2013-09-19,Lorentz-invariant three-vectors and alternative formulation of relativistic dynamics,"Besides the well known scalar invariants, there exist also vectorial
invariants in the realm of special relativity. It is shown that the
three-vector $\left(\frac{d\vec{p}}{dt}\right)_{\parallel
v}+\gamma_v\left(\frac{d\vec{p}}{dt}\right)_{\perp v}$ is invariant under the
Lorentz transformation. The indices $_{\parallel v}$ and $_{\perp v}$ denote
the respective components established with respect to the direction of the
velocity of body $\vec{v}$, and $\vec{p}$ is the relativistic momentum. We
prove that this vector is equal to a force of $\vec{F}_R$ satisfying the
classical Newtonian law $\vec{F}_R=m\vec{a}_R$ in the instantaneous inertial
rest frame of an accelerated body. Therefore the equation
$\vec{F}_R=\left(\frac{d\vec{p}}{dt}\right)_{\parallel
v}+\gamma_v\left(\frac{d\vec{p}}{dt}\right)_{\perp v}$, based on the
Lorentz-invariant vectors, may be used as a truly invariant (not merely a
covariant) relativistic equation of motion in any inertial system of reference.
An alternative approach to classical electrodynamics based on the invariant
three-vectors is proposed.",1309.6533v1
2013-09-16,How (not) to teach Lorentz covariance of the Dirac equation,"In the textbook proofs of Lorentz covariance of the Dirac equation, one
treats the wave function as a spinor and gamma matrices as scalars, leading to
a quite complicated formalism with several pedagogic drawbacks. As an
alternative, I propose to teach Dirac equation and its Lorentz covariance by
using a much simpler, but physically equivalent formalism, in which these
drawbacks do not appear. In this alternative formalism, the wave function
transforms as a scalar and gamma matrices as components of a vector, such that
the standard physically relevant bilinear combinations do not change their
transformation properties. The alternative formalism allows also a natural
construction of some additional non-standard bilinear combinations with
well-defined transformation properties.",1309.7070v2
2014-05-09,Non equilibrium density profiles in Lorentz tubes with thermostated boundaries,"We consider a long Lorentz tube with absorbing boundaries. Particles are
injected to the tube from the left end. We compute the equilibrium density
profiles in two cases: the semi-infinite tube (in which case the density is
constant) and a long finite tube (in which case the density is linear). In the
latter case, we also show that convergence to equilibrium is well described by
the heat equation. In order to prove these results, we obtain new results for
the Lorentz particle which are of independent interest. First, we show that a
particle conditioned not to hit the boundary for a long time converges to the
Brownian meander. Second, we prove several local limit theorems for particles
having a prescribed behavior in the past.",1405.2304v1
2014-06-03,A Lorentz invariant velocity distribution for a relativistic gas,"We derive a Lorentz invariant distribution of velocities for a relativistic
gas. Our derivation is based on three pillars: the special theory of
relativity, the central limit theorem and the Lobachevskyian structure of the
velocity space of the theory. The rapidity variable plays a crucial role in our
results. For $v^2/c^2 \ll 1$ and $1/\beta=kT/2 m_0 c^2 \ll 1$ the distribution
tends to the Maxwell-Boltzmann distribution. The mean $\langle v^2 \rangle$
evaluated with the Lorentz invariant distribution is always smaller than the
Maxwell-Boltzmann mean and is bounded by $\langle v^2 \rangle/c^2=1$. This
implies that for a given $\langle v^2 \rangle$ the temperature is larger than
the temperature estimated using the Maxwell-Boltzmann distribution. For
temperatures of the order of $T \sim {10^{12}}~ K$ and $T \sim {10^{8}}~ K$ the
difference is of the order of $10 \%$, respectively for particles with the
hydrogen and the electron rest masses.",1406.0777v1
2014-06-09,Quasihomogeneous three-dimensional real analytic Lorentz metrics do not exist,"We show that a germ of a real analytic Lorentz metric on ${\bf R}^3$ which is
locally homogeneous on an open set containing the origin in its closure is
necessarily locally homogeneous. We classifiy Lie algebras that can act
quasihomogeneously---meaning they act transitively on an open set admitting the
origin in its closure, but not at the origin---and isometrically for such a
metric. In the case that the isotropy at the origin of a quasihomogeneous
action is semisimple, we provide a complete set of normal forms of the metric
and the action.",1406.2302v2
2014-06-18,Lorentz violation from gamma-ray bursts,"The constancy of light speed is a basic assumption in Einstein's special
relativity, and consequently the Lorentz invariance is a fundamental symmetry
of space-time in modern physics. However, it is speculated that the speed of
light becomes energy-dependent due to the Lorentz invariance violation~(LV) in
various new physics theories. We analyse the data of the energetic photons from
the gamma-ray bursts (GRBs) by the Fermi Gamma-Ray Space Telescope, and find
more events to support the energy dependence in the light speed with both
linear and quadratic form corrections. We provide two scenarios to understand
all the new-released Pass~8 data of bright GRBs by the Fermi-LAT Collaboration,
with predictions from such scenarios being testable by future detected GRBs.",1406.4568v1
2015-12-14,"A manifestly Lorentz covariant, interacting and non-commutative Dirac equation","We propose a manifestly Lorentz covariant, non-commutative Dirac equation for
charged particles interacting with an electromagnetic field. The equation is
formulated on the operator level, but operators are not composed through the
normal operator product, but a modified product that restores the Lorentz
covariance. This equation is solved for the free particle and a particle moving
in a constant magnetic field. An abstract action, constructed on the operator
level, that yields this equation as equation of motion is also derived. To
relate this formalism to current formulations of non-commutative quantum field
theories, this action is written in a coherent state basis, leading to an
action in 4-dimensional Minkowski space-time. The resulting action differs from
existing non-commutative actions, but still exhibits non-commutative effects
through non-locality.",1512.04253v2
2016-05-24,Correspondence between Einstein-Yang-Mills-Lorentz systems and dynamical torsion models,"In the framework of Einstein-Yang-Mills theories, we study the gauge Lorentz
group and establish a particular correspondence between this case and a certain
class of theories with torsion within Riemann-Cartan space-times. This relation
is specially useful in order to simplify the problem of finding exact solutions
to the Einstein-Yang-Mills equations. The applicability of the method is
divided into two approaches: one associated with the Lorentz group SO(1,n-1) of
the space-time rotations and another one with its subgroup SO(n-2). Solutions
for both cases are presented by the explicit use of this correspondence and,
interestingly, for the last one by imposing on our ansatz the same kind of
rotation and reflection symmetry properties as for a nonvanishing space-time
torsion. Although these solutions were found in previous literature by a
different approach, our method provides an alternative way to obtain them and
it may be used in future research to find other exact solutions within this
theory.",1605.07664v2
2016-05-25,Lorentz violation in simple QED processes,"We determine the effect of a CPT-even and Lorentz violating non-minimal
coupling on the differential cross sections for some of the most important
tree-level processes in QED, namely, Compton and Bhabha scatterings, as well as
electron-positron annihilation. Experimental limits constraining the allowed
deviation of the differential cross sections relative to pure QED allow us to
place upper bounds on the Lorentz violating parameters. A constraint based on
the decay rate of para-positronium is also obtained.",1605.08059v3
2016-08-29,Lorentz-violating spinor electrodynamics and Penning traps,"The prospects are explored for testing Lorentz- and CPT-violating quantum
electrodynamics in experiments with Penning traps. We present the Lagrange
density of Lorentz-violating spinor electrodynamics with operators of mass
dimensions up to six, and we discuss some of its properties. The theory is used
to derive Lorentz- and CPT-violating perturbative shifts of the energy levels
of a particle confined to a Penning trap. Observable signals are discussed for
trapped electrons, positrons, protons, and antiprotons. Existing experimental
measurements on anomaly frequencies are used to extract new or improved bounds
on numerous coefficients for Lorentz and CPT violation, using sidereal
variations of observables and comparisons between particles and antiparticles.",1608.07868v1
2016-08-17,Teleparallel equivalent of general relativity and local Lorentz transformation: Revisited,"It is well known that the field equations of teleparallel theory which is
equivalent to general relativity (TEGR) completely agree with the field
equation of general relativity (GR). However, TEGR has six extra degrees of
freedom which spoil the true physics. These extra degrees are related to the
local Lorentz transformation. In this study, we give three different tetrads of
flat horizon space-time that depend only on the radial coordinate. One of these
tetrads contains an arbitrary function which comes from local Lorentz
transformation. We show by explicate calculations that this arbitrary function
spoils the calculations of the conserved charges. We formulate {\it a
skew-symmetric tensor} whose vanishing value put a constraint on the arbitrary
function. This constraint makes the conserved charges are free from the
arbitrary function.",1608.08857v1
2016-12-12,Quantizations of D=3 Lorentz symmetry,"Using the isomorphism
$\mathfrak{o}(3;\mathbb{C})\simeq\mathfrak{sl}(2;\mathbb{C})$ we develop a new
simple algebraic technique for complete classification of quantum deformations
(the classical $r$-matrices) for real forms $\mathfrak{o}(3)$ and
$\mathfrak{o}(2,1)$ of the complex Lie algebra $\mathfrak{o}(3;\mathbb{C})$ in
terms of real forms of $\mathfrak{sl}(2;\mathbb{C})$: $\mathfrak{su}(2)$,
$\mathfrak{su}(1,1)$ and $\mathfrak{sl}(2;\mathbb{R})$. We prove that the $D=3$
Lorentz symmetry
$\mathfrak{o}(2,1)\simeq\mathfrak{su}(1,1)\simeq\mathfrak{sl}(2;\mathbb{R})$
has three different Hopf-algebraic quantum deformations which are expressed in
the simplest way by two standard $\mathfrak{su}(1,1)$ and
$\mathfrak{sl}(2;\mathbb{R})$ $q$-analogs and by simple Jordanian
$\mathfrak{sl}(2;\mathbb{R})$ twist deformations. These quantizations are
presented in terms of the quantum Cartan-Weyl generators for the quantized
algebras $\mathfrak{su}(1,1)$ and $\mathfrak{sl}(2;\mathbb{R})$ as well as in
terms of quantum Cartesian generators for the quantized algebra
$\mathfrak{o}(2,1)$. Finaly, some applications of the deformed $D=3$ Lorentz
symmetry are mentioned.",1612.03866v2
2016-12-15,Collisions near Kerr black holes: lower limit of energy between orbiting and incoming particles,"In our paper we investigate the lower limit of collisional energy of test
particles near the Kerr black hole. In particular we examine the minimal
Lorentz factor between the freely falling particles and the particles orbiting
around a black hole. We consider collisions on the innermost stable circular
orbit (ISCO) and examine near--extreme case, where collisions take place near
an event horizon. By fine--tuning the particles' angular momentum, the Lorentz
factor of the collision can always be minimized to a value dependent on the
black hole's spin. We identified that this minimal value is always less than
$\frac{2\sqrt{2}-1}{\sqrt{3}}$ and more than $\frac{\sqrt{12}-1}{\sqrt{6}}$
(the limits are the values for an extreme Kerr and Schwarzschild,
respectively). It implies that this kind of collisions of compact objects are
expected to be highly energetic near supermassive black holes. In addition, we
show that an interaction between black hole's and particle's spins has an
influence on minimal Lorentz factor. This contribution is nonnegligible for
near--extreme black holes. We also discuss the relation between our results and
sci--fi movie Interstellar.",1612.05302v1
2017-06-08,Charging due to Pair-Potential Gradient in Vortex of Type-II Superconductors,"Besides the magnetic Lorentz force familiar from the Hall effect in metals
and semiconductors, there exists a mechanism for charging peculiar to
superconductors that is caused by the pair-potential gradient (PPG). We
incorporate it in the augmented quasiclassical equations of superconductivity
with the Lorentz force to study charging of an isolated vortex in an
equilibrium s-wave type-II superconductor. It is found that the PPG mechanism
gives rise to charging concentrated within the core whose magnitude at the core
center can be 10 to 100 times larger than that caused by the Lorentz force. Our
detailed calculations on the spatial, temperature, and
magnetic-penetration-depth dependences of the vortex-core charge reveal that
the PPG mechanism contributes dominantly to the core charging of the isolated
vortex over a wide parameter range. The two mechanisms are also found to work
additively at the core center for the present model with an isotropic Fermi
surface.",1706.02449v2
2017-06-14,Van der Waals-like phase transition from holographic entanglement entropy in Lorentz breaking massive gravity,"In this paper, phase transition of AdS black holes in lorentz breaking
massive gravity has been studied in the framework of holography. We find that
there is a first order phase transition(FPT) and second order phase
transition(SPT) both in Bekenstein-Hawking entropy(BHE)-temperature plane and
holographic entanglement entropy(HEE)-temperature plane. Furthermore, for the
FPT, the equal area law is checked and for the SPT, the critical exponent of
the heat capacity is also computed. Our results confirm that the phase
structure of HEE is similar to that of BHE in lorentz breaking massive gravity,
which implies that HEE and BHE have some potential underlying relationship.",1706.04431v1
2017-06-21,Lorentz-violating nonminimal coupling contributions in mesonic hydrogen atoms and generation of photon higher-order derivative terms,"We have studied the contributions of Lorentz-violating CPT-odd and CPT-even
nonminimal couplings to the energy spectrum of the mesonic hydrogen and the
higher-order radiative corrections to the effective action of the photon sector
of a Lorentz-violating version of the scalar electrodynamics. By considering
the complex scalar field describes charged mesons (pion or kaon), the
non-relativistic limit of the model allows to attain upper-bounds by analyzing
its contribution to the mesonic hydrogen energy. By using the experimental data
for the $1S$ strong correction shift and the pure QED transitions $4P
\rightarrow 3P$, the best upper-bound for the CPT-odd coupling is
$<10^{-12}\text{eV}^{-1}$ and for the CPT-even one is
$<10^{-16}\text{eV}^{-2}$. Besides, the CPT-odd radiative correction to the
photon action is a dimension-5 operator which looks like a higher-order
Carroll-Field-Jackiw term. The CPT-even radiative contribution to the photon
effective action is a dimension-6 operator which would be a higher-order
derivative version of the minimal CPT-even term of the standard model
extension.",1706.07117v2
2017-06-22,Stability of Effective Thin-shell Wormholes Under Lorentz Symmetry Breaking Supported by Dark Matter and Dark Energy,"In this paper, we construct generic, spherically symmetric thin-shell
wormholes and check their stabilities using the unified dark sector, including
dark energy and dark matter. We give a master equation, from which one can
recover, as a special case, other stability solutions for generic spherically
symmetric thin-shell wormholes. In this context, we consider a particular
solution; namely we construct an effective thin-shell wormhole under Lorentz
symmetry breaking. We explore stability analyses using different models of the
modified Chaplygin gas with constraints from cosmological observations such as
seventh-year full Wilkinson microwave anisotropy probe data points, type Ia
supernovae, and baryon acoustic oscillation. In all these models we find stable
solutions by choosing suitable values for the parameters of the Lorentz
symmetry breaking effect.",1706.07656v2
2017-06-26,"Fluctuating, Lorentz-force-like coupling of Langevin equations and heat flux rectification","In a description of physical systems with Langevin equations, interacting
degrees of freedom are usually coupled through symmetric parameter matrices.
This coupling symmetry is a consequence of time-reversal symmetry of the
involved conservative forces. If coupling parameters fluctuate randomly, the
resulting noise is called multiplicative. For example, mechanical oscillators
can be coupled through a fluctuating, symmetric matrix of spring ""constants"".
Such systems exhibit well-studied instabilities. In this note, we study the
complementary case of antisymmetric, time-reversal symmetry breaking coupling
that can be realized with Lorentz forces or various gyrators. We consider the
case that these antisymmetric couplings fluctuate. This type of multiplicative
noise does not lead to instabilities in the stationary state but renormalizes
the effective non-equilibrium friction. Fluctuating Lorentz-force-like
couplings also allow to control and rectify heat transfer. A noteworthy
property of this mechanism of producing asymmetric heat flux is that the
controlling couplings do not exchange energy with the system..",1706.08367v3
2017-06-27,Compton Edge probing basic physics at Jefferson Laboratory: light speed isotropy and Lorentz invariance,"We propose to study of the light speed isotropy and Lorentz invariance at
Jefferson Laboratory by means of the measurements of the Compton Edge using of
the Hall A/C existing experimental setup. Methodologically the same experiment
has already been successfully elaborated at GRAAL experiment at the European
Synchrotron Radiation Facility in Grenoble with 6 GeV electron beam. This
Proposal states two goals expected to be reached at Jefferson Laboratory, both
on Lorentz invariance: (a) the one-way light speed isotropy testing accuracy,
following from conservative evaluations at numerical simulations, to about an
order of magnitude better than was GRAAL's; (b) the dependence of the light
speed on the velocity of the apparatus (Kennedy-Thorndike measurement) will be
traced to an accuracy about 3 orders of magnitudes better than the available
limits.",1706.08907v1
2017-07-11,Superalgebraic structure of Lorentz transformations,"Modern relativistic theory of the second quantization of fermion and boson
fields is based on the use of the mathematical apparatus of C*-algebras and Lie
superalgebras. In this case, for fermions, the Lorentz transformations are
considered as Bogolyubov transformations of creation and annihilation
operators. However, in this approach one can not obtain an explicit form of the
Dirac gamma-matrices. The mathematical apparatus of the superalgebraic
representation of the algebra of the second quantization of spinors is
developed in the article. It is based on the use of density in the impulse
space of Grassmann variables and their derivatives. It is shown that the Dirac
matrices and the Lorentz transformation generators can be expressed in terms of
such densities. A superalgebraic form of the Dirac equation and the vacuum
state vector are constructed. It is shown that in the superalgebraic form of
the complex Clifford algebra the generators corresponding to the Dirac gamma
matrices are not equivalent. Clifford vector corresponding to diagonal matrix
annihilates the vacuum, and the remaining ones give nonzero values. This means
that there is asymmetric direction corresponding to the time axis",1707.03687v1
2017-10-02,New test of Lorentz symmetry using ultrahigh-energy cosmic rays,"We propose an innovative test of Lorentz symmetry by observing pairs of
simultaneous parallel extensive air showers produced by the fragments of
ultrahigh-energy cosmic ray nuclei which disintegrated in collisions with solar
photons. We show that the search for a cross-correlation of showers in arrival
time and direction becomes background free for an angular scale < 3^\circ and a
time window {\cal O}(10 s). We also show that if the solar photo-disintegration
probability of helium is {\cal O} (10^{-5.5}) then the hunt for spatiotemporal
coincident showers could be within range of existing cosmic ray facilities,
such as the Pierre Auger Observatory. We demonstrate that the actual
observation of a few events can be used to constrain Lorentz violating
dispersion relations of the nucleon.",1710.00750v3
2017-12-12,Dispersion of particles in an infinite-horizon Lorentz gas,"We consider a two-dimensional Lorentz gas with infinite horizon. This
paradigmatic model consists of pointlike particles undergoing elastic
collisions with fixed scatterers arranged on a periodic lattice. It was
rigorously shown that when $t\to\infty$, the distribution of particles is
Gaussian. However, the convergence to this limit is ultraslow, hence it is
practically unattainable. Here we obtain an analytical solution for the Lorentz
gas' kinetics on physically relevant timescales, and find that the density in
its far tails decays as a universal power law of exponent $-3$. We also show
that the arrangement of scatterers is imprinted in the shape of the
distribution.",1712.04397v4
2017-12-27,New ideas for tests of Lorentz invariance with atomic systems,"We describe a broadly applicable experimental proposal to search for the
violation of local Lorentz invariance (LLI) with atomic systems. The new scheme
uses dynamic decoupling and can be implemented in current atomic clocks
experiments, both with single ions and arrays of neutral atoms. Moreover, the
scheme can be performed on systems with no optical transitions, and therefore
it is also applicable to highly charged ions which exhibit particularly high
sensitivity to Lorentz invariance violation. We show the results of an
experiment measuring the expected signal of this proposal using a two-ion
crystal of $^{88}$Sr$^+$ ions. We also carry out a systematic study of the
sensitivity of highly charged ions to LLI to identify the best candidates for
the LLI tests.",1712.09514v2
2017-12-21,The Simplest Form of the Lorentz Transformations,"We report the simplest possible form to compute rotations around arbitrary
axis and boosts in arbitrary directions for 4-vectors (space-time points,
energy-momentum) and bi-vectors (electric and magnetic field vectors) by
symplectic similarity transformations. The Lorentz transformations are based
exclusively on real $4\times 4$-matrices and require neither complex numbers
nor special implementations of abstract entities like quaternions or Clifford
numbers. No raising or lowering of indices is necessary. It is explained how
the Lorentz transformations can be derived from the most simple second order
Hamiltonian of general significance. Since this approach exclusively uses the
real Clifford algebra $Cl(3,1)$, all calculations are based on real $4\times 4$
matrix algebra.",1801.01840v3
2018-01-29,Long-range Self-assembly via the Mutual Lorentz Force of Plasmon Radiation,"Long-range interactions often proceed as a sequence of hopping through
intermediate, statistically-favored events. Here, we identify a
widely-overlooked mechanism for the mechanical motion of particles that arises
from the Lorentz force and plasmon radiation. Even if the radiation is weak,
the nonconservative Lorentz force produces stable locations perpendicular to
the plasmon oscillation; over time, distinct patterns emerge. Experimentally,
linearly-polarized light leads to the formation of 80-nm Au nanoparticles,
perpendicularly-aligned, with lengths that are orders of magnitude greater than
their plasmon near-field interaction. There is a critical intensity threshold
and optimal concentration for observing self-assembly.",1801.09331v1
2018-09-26,Improved Test of Local Lorentz Invariance from a Deterministic Preparation of Entangled States,"The high degree of control available over individual atoms enables precision
tests of fundamental physical concepts. In this Letter, we experimentally study
how precision measurements can be improved by preparing entangled states immune
to the dominant source of decoherence. Using \Ca ions, we explicitly
demonstrate the advantage from entanglement on a precision test of local
Lorentz invariance for the electron. Reaching the quantum projection noise
limit set by quantum mechanics, we observe for bipartite entangled states the
expected gain of a factor of two in the precision. Under specific conditions,
multipartite entangled states may yield substantial further improvements. Our
measurements improve the previous best limit for local Lorentz invariance of
the electron using \Ca ions by factor of two to four to about
$5\times10^{-19}$.",1809.09807v2
2018-09-27,Optical clock comparison test of Lorentz symmetry,"Questioning the presumably most basic assumptions about the structure of
space and time has revolutionized our understanding of Nature. State-of-the-art
atomic clocks make it possible to precisely test fundamental symmetry
properties of spacetime, and search for physics beyond the standard model at
low energy scales of just a few electron volts. Here, we experimentally
demonstrate for the first time agreement of two single-ion clocks at the
$10^{-18}$ level and directly confirm the validity of their uncertainty budgets
over a half-year long comparison period. The two clock ions are confined in
separate ion traps with quantization axes aligned along nonparallel directions.
Hypothetical Lorentz symmetry violations would lead to sidereal modulations of
the frequency offset. From the absence of such modulations at the $10^{-19}$
level we deduce stringent limits on Lorentz symmetry violation parameters for
electrons in the range of $10^{-21}$, improving previous limits by two orders
of magnitude.",1809.10742v1
2018-09-30,"Superboost transitions, refraction memory and super-Lorentz charge algebra","We derive a closed-form expression of the orbit of Minkowski spacetime under
arbitrary Diff$(S^2)$ super-Lorentz transformations and supertranslations. Such
vacua are labelled by the superboost, superrotation and supertranslation
fields. Impulsive transitions among vacua are related to the refraction memory
effect and the displacement memory effect. A phase space is defined whose
asymptotic symmetry group consists of arbitrary Diff$(S^2)$ super-Lorentz
transformations and supertranslations. It requires a renormalization of the
symplectic structure. We show that our final surface charge expressions are
consistent with the leading and subleading soft graviton theorems. We contrast
the leading BMS triangle structure to the mixed overleading/subleading BMS
square structure.",1810.00377v3
2018-10-03,Lorentz violation from gamma-ray burst neutrinos,"The Lorentz violation~(LV) effect of ultra-relativistic particles can be
tested by gamma-ray burst~(GRB) neutrinos and photons. The IceCube
Collaboration has observed plenty of ultra-high energy neutrinos, including
four events of PeV scale neutrinos. Recent studies suggested a possible energy
dependent speed variation of GRB neutrinos in a similar way to that of GRB
photons. Here we find that all four events of PeV neutrinos with associated GRB
candidates can satisfy a regularity found from TeV neutrinos about a linear
form correlation between the observed time difference and the LV factor. Such
regularity indicates a Lorentz violation scale $E_{\rm LV}=(6.5\pm
0.4)\times10^{17}~{\rm GeV}$, which is comparable with that determined by GRB
photons. We also suggest that neutrinos and anti-neutrinos can be superluminal
and subluminal respectively due to opposite signs of LV correction.",1810.01652v1
2018-10-09,Antisymmetric tensor propagator with spontaneous Lorentz violation,"In this work, we study the spontaneous Lorentz symmetry breaking due to an
antisymmetric 2-tensor field in Minkowski spacetime. For a smooth quadratic
potential, the spectrum of the theory exhibits massless and massive
excitations. We show that the equations of motion for the free field obey some
constraints which lead to the massive mode be non-propagating at leading order.
Besides, there exists a massless mode in the theory which can be identified
with the usual Kalb-Ramond field, carrying only one on-shell degree of freedom.
The same conclusion holds when one analyses the pole structure of its Feynman
propagator. A new complete set of spin-type operators is found, which was the
requirement to evaluate the propagator of the Kalb-Ramond field modified by the
presence of a nonzero vacuum expectation value responsible for the Lorentz
violation.",1810.04003v2
2018-10-22,Constraints and degrees of freedom in Lorentz-violating field theories,"Many current models which ""violate Lorentz symmetry"" do so via a vector or
tensor field which takes on a vacuum expectation value, thereby spontaneously
breaking the underlying Lorentz symmetry of the Lagrangian. To obtain a tensor
field with this behavior, one can posit a smooth potential for this field, in
which case it would be expected to lie near the minimum of its potential.
Alternately, one can enforce a non-zero tensor value via a Lagrange multiplier.
The present work explores the relationship between these two types of theories
in the case of vector models. In particular, the na\""ive expectation that a
Lagrange multiplier ""kills off"" one degree of freedom via its constraint does
not necessarily hold for vector models that already contain primary
constraints. It is shown that a Lagrange multiplier can only reduce the degrees
of freedom of a model if the field-space function defining the vacuum manifold
commutes with the primary constraints.",1810.09512v2
2019-06-09,A Lorentz-Covariant Interacting Electron-Photon System in One Space Dimension,"A Lorenz-covariant system of wave equations is formulated for a
quantum-mechanical two-body system in one space dimension, comprised of one
electron and one photon. Manifest Lorentz covariance is achieved using Dirac's
formalism of multi-time wave functions, i.e., wave functions
$\Psi(\mathbf{x}_{{ph}},\mathbf{x}_{{el}})$ where
$\mathbf{x}_{{el}},\mathbf{x}_{{ph}}$ are the generic spacetime events of the
electron and photon, respectively. Their interaction is implemented via a
Lorentz-invariant no-crossing-of-paths boundary condition at the coincidence
submanifold $\{\mathbf{x}_{{el}}=\mathbf{x}_{{ph}}\}$, compatible with particle
current conservation. The corresponding initial-boundary-value problem is
proved to be well-posed. Electron and photon trajectories are shown to exist
globally in a Hypersurface Bohm--Dirac theory, for typical particle initial
conditions. Also presented are the results of some numerical experiments which
illustrate Compton scattering as well as a new phenomenon: photon capture and
release by the electron.",1906.03632v2
2019-06-11,Generalized Lorentz reciprocal theorem in complex fluids and in non-isothermal systems,"The classical Lorentz reciprocal theorem (LRT) was originally derived for
slow viscous flows of incompressible Newtonian fluids under the isothermal
condition. In the present work, we extend the LRT from simple to complex fluids
with open or moving boundaries that maintain non-equilibrium stationary states.
In complex fluids, the hydrodynamic flow is coupled with the evolution of
internal degrees of freedom such as the solute concentration in two-phase
binary fluids and the spin in micropolar fluids. The dynamics of complex fluids
can be described by local conservation laws supplemented with local
constitutive equations satisfying Onsager's reciprocal relations (ORR). We
consider systems in quasi-stationary states close to equilibrium, controlled by
the boundary variables whose evolution is much slower than the relaxation in
the system. For these quasi-stationary states, we derive the generalized
Lorentz reciprocal theorem (GLRT) and global Onsager's reciprocal relations
(GORR) for the slow variables at boundaries. This establishes the connection
between ORR for local constitutive equations and GORR for constitutive
equations at boundaries. Finally, we show that the LRT can be further extended
to non-isothermal systems by considering as an example the thermal conduction
in solids and still fluids.",1906.04458v1
2019-06-14,Lorentz violation constraints with astroparticle physics,"Astroparticle physics has recently reached a new status of precision due to
the construction of new observatories, operating innovative technologies and
the detection of large numbers of events and sources. The precise measurements
of cosmic and gamma rays can be used as a test for fundamental physics, such as
the Lorentz invariance violation (LV). Although LV signatures are expected to
be small, the very high energies and long distances that astrophysical sources
involve, lead to an unprecedented opportunity for this task. In this summary,
exclusion limits results are presented from different types of astrophysical LV
tests through the generic modification of the particle dispersion relation in
the photon sector through the pair production threshold shifts and photon
decay. Some perspectives for the next generations of gamma-ray telescopes are
also addressed",1906.06293v1
2019-06-18,Consistent Lorentz violation features from near-TeV IceCube neutrinos,"A recent proposal to associate 60~TeV to 2~PeV IceCube neutrino events with
gamma-ray bursts~(GRBs) indicates the Lorentz violation of cosmic neutrinos and
leads further to the $CPT$ symmetry violation between neutrinos and
antineutrinos. Here we find that another 12 northern hemisphere track events
possibly correlated with GRBs from three-year IceCube data satisfy the same
regularity at a lower energy scale around 1~TeV. The combined fitting indicates
a Lorentz violation scale ${E}_{\rm LV}=(6.4\pm 1.5)\times10^{17}~{ \rm GeV}$
and an intrinsic time difference ${\Delta {t}_{\rm in}=(-2.8\pm
0.7)\times10^2~{\rm s}}$, from which we find an earlier emission of neutrinos
than photons at the GRB source. We also suggest analyzing neutrino events
detected a few minutes before the GRB trigger time to test the $CPT$ violation
of ultrahigh-energy neutrinos.",1906.07329v2
2019-06-19,New constraints on Lorentz Invariance violation from Crab Nebula spectrum beyond $100$ TeV,"Recently two collaborations, Tibet and HAWC, presented new measurements of
gamma-ray spectrum from Crab Nebula
\cite{Amenomori:2019rjd},\cite{Abeysekara:2019edl} which continues beyond $100$
TeV. We use these data to establish two-sided constraints on parameters of
Lorentz Invariance violation in quantum electrodynamics. The limits on Lorentz
violating mass scale for quartic dispersion relation are $4.1\times 10^{14}\
\mbox{GeV}$ (photon splitting) and $1.9\times 10^{13}\ \mbox{GeV}$ (photon
decay) for superluminal case, and $1.4\times 10^{12}$ GeV (suppression of
shower formation) for subluminal case.",1906.08221v4
2019-07-10,The point-charge self-energy in a nonminimal Lorentz violating Maxwell Electrodynamics,"In this letter we study the self-energy of a point-like charge for the
electromagnetic field in a non minimal Lorentz symmetry breaking scenario in a
$n+1$ dimensional space time. We consider two variations of a model where the
Lorentz violation is caused by a background vector $d^{\nu}$ that appears in a
higher derivative interaction. We restrict our attention to the case where
$d^{\mu}$ is a time-like background vector, namely $d^{2}=d^{\mu}d_{\mu}>0$,
and we verify that the classical self-energy is finite for any odd spatial
dimension $n$ and diverges for even $n$. We also make some comments regarding
obstacles in the quantization of the proposed model.",1907.04735v1
2019-07-25,Bipartite-Finsler symmetries,"In this work, we study the symmetries of a Lorentz violating
bipartite-Finsler spacetime. By using the Finslerian Killing equation for the
bipartite-Finsler metric, we analyze how the anisotropy of the bipartite
spacetime modifies the local Lorentz symmetries. The symmetries of the Finsler
metric allow us to obtain the bipartite algebra and interpreted it as a
deformed Lorentz algebra. Causality effects driven by the particle modified
dispersion relations are investigated upon Minkowski and the Schwarzschild
spacetimes. The background bipartite tensor yields to superluminal velocities
and modifies the effective gravitational potential.",1907.11214v2
2019-09-22,New regularity criteria based on pressure or gradient of velocity in Lorentz spaces for the 3D Navier-Stokes equations,"In this paper, we derive regular criteria via pressure or gradient of the
velocity in Lorentz spaces to the 3D Navier-Stokes equations. It is shown that
a Leray-Hopf weak solution is regular on $(0,T]$ provided that either the norm
$\|\Pi\|_{L^{p,\infty}(0,T; L ^{q,\infty}(\mathbb{R}^{3}))} $ with $
{2}/{p}+{3}/{q}=2$ $({3}/{2}<q<\infty)$ or $\|\nabla\Pi\|_{L^{p,\infty}(0,T; L
^{q,\infty}(\mathbb{R}^{3}))} $ with $ {2}/{p}+{3}/{q}=3$ $(1<q<\infty)$ is
small. This gives an affirmative answer to a question proposed by Suzuki in
[26, Remark 2.4, p.3850]. Moreover, regular conditions in terms of $\nabla u$
obtained here generalize known ones to allow the time direction to belong to
Lorentz spaces.",1909.09960v1
2019-09-23,Breaking of Lorentz Invariance in Electron-Proton Parity Violation,"A popular framework for exploring Lorentz violation is the Standard Model
Extension. This extension contains a large number of parameters that can be
bounded in various experiments. Most studies, however, focus on the fermion or
photon sector. Here, we consider Lorentz violation in the weak vector boson
sector. The strongest bounds come from measurements of the asymmetry in Moller
scattering. We study the bounds that can be obtained from future measurements
of the parity violating asymmetry in deep inelastic electron-proton scattering
at the EIC, the LHeC and the FCC-eh. For the FCC-eh, the bounds could be
substantially improved over current bounds by including timing information.",1909.10627v2
2020-02-08,Collision of particles near a three-dimensional rotating Hořava AdS black hole,"We consider a three-dimensional rotating Ho\v{r}ava AdS black hole, that
corresponds to a Lorentz-violating version of the BTZ black hole and we analyze
the effect of the breaking of Lorentz invariance on the possibility that the
black hole can acts as a particle accelerator by analyzing the energy in the
center of mass (CM) frame of two colliding particles in the vicinity of its
horizons. We find that the critical angular momentum of particles increases
when the Ho\v{r}ava parameter $\xi$ increases and when the aether parameter $b$
increases. Also, the particles can collide on the inner horizon with
arbitrarily high CM energy if one of the particles has a critical angular
momentum being possible the BSW process, for the non-extremal rotating
Ho\v{r}ava AdS black hole. Mainly, while that for the extremal BTZ black hole
the particles with critical angular momentum only can exist on the degenerate
horizon, for the Lorentz-violating version of the BTZ black hole the particle
with critical angular momentum can exist in a region from the degenerate
horizon.",2002.04421v1
2020-02-25,On-Shell Electric-Magnetic Duality and the Dual Graviton,"Using on-shell amplitude methods, we explore 4-dimensional Electric-Magnetic
duality and its double copy. We show explicitly that the on-shell scattering
amplitudes know about `dual' photons (and dual gravitons), that the off-shell
photon propagator double copies to the graviton propagator and that the
magnetic part of the propagator is essential for the double copy to hold. We
also show that there is an equivalent gravito-magnetic part of the graviton
propagator which is essential in giving rise to solutions with either angular
momentum or NUT charge. Furthermore, we comment on the so-called Weinberg
paradox, which states that scattering amplitudes involving the mixing of
electric and magnetic monopoles cannot be Lorentz invariant, and would seem to
preclude the existence of the 't Hooft-Polyakov (topological) monopole. We
trace this paradox to the magnetic part of the propagator, showing that it can
be eliminated if one restricts to proper orthochronous Lorentz transformations.
Finally, we compute the fully relativistic cross-section for arbitrary spin
dyons using the recently formulated on-shell duality transformation and show
that this is always fully Lorentz invariant.",2002.11085v1
2020-04-16,Lifshitz-scaling in CPT-even Lorentz-violating electrodynamics and GRB time delay,"In this work, we consider the Ho\v{r}ava-Lifshitz scaling to rewrite
higher-order derivatives in Lorentz-violating CPT-even electrodynamics. The
possibility of the Lorentz invariance violation being originally suppressed by
the quantum gravity energy scale $M_{\rm QG}$, may be indeed circumvented in a
scenario with anisotropy between space and time above certain intermediate
energy scale $\Lambda_{\rm HL} \ll M_{\rm QG}$. To test the model, we have used
observational results of a cosmological time delay between high and low energy
photons from gamma ray bursts (GRB090510) event. For specific values of the
Lifshitz critical exponent, we have found interesting lower bounds on the
values of $M_{\rm QG}$.",2004.07661v5
2020-04-19,Anomalous Lorentz transformation and side jump of a massive fermion,"The side jump in the anomalous Lorentz transformation, arising from the
spin-orbit interactions, plays important roles in various intriguing physics,
such as chiral vortical effects and spin polarization. In this work, the side
jump of the spin-half massive particles, which has rarely been discussed, is
visualized and evaluated for the first time. A compact analytical expression
describing such side jumps is derived, and found approaching the one describing
the chiral fermions in the massless limit. It is further demonstrated that the
covariance of the total angular momentum, which would be broken by a normal
Lorentz transformation, is restored after the obtained side jumps are taken
into account.",2004.08910v1
2020-04-24,Brownian motion at the speed of light: a Lorentz invariant family of processes,"We recently introduced a new family of processes which describe particles
which only can move at the speed of light c in the ordinary 3D physical space.
The velocity, which randomly changes direction, can be represented as a point
on the surface of a sphere of radius c and its trajectories only may connect
the points of this variety. A process can be constructed both by considering
jumps from one point to another (velocity changes discontinuously) and by
continuous velocity trajectories on the surface. We followed this second new
strategy assuming that the velocity is described by a Wiener process (which is
isotropic only in the 'rest frame') on the surface of the sphere. Using both
Ito calculus and Lorentz boost rules, we succeed here in characterizing the
entire Lorentz-invariant family of processes. Moreover, we highlight and
describe the short-term ballistic behavior versus the long-term diffusive
behavior of the particles in the 3D physical space.",2004.11983v2
2020-12-15,Bloch-Lorentz magnetoresistance oscillations in delafossites,"Recent measurements of the out-of-plane magnetoresistance of delafossites
(PdCoO$_2$ and PtCoO$_2$) observed oscillations closely resembling the
Aharonov-Bohm effect. Here, we show that the magnetoresistance oscillations are
explained by the Bloch-like oscillations of the out-of-plane electron
trajectories. We develop a semiclassical theory of these Bloch-Lorentz
oscillations and show that they are a consequence of the ballistic motion and
quasi-2D dispersion of delafossites. Our model identifies the sample wall
scattering to be the most likely factor limiting the visibility of these
Bloch-Lorentz oscillations in existing experiments.",2012.08552v4
2021-01-07,Heisenberg doubles for Snyder type models,"A Snyder model generated by the noncommutative coordinates and Lorentz
generators close a Lie algebra. The application of the Heisenberg double
construction is investigated for the Snyder coordinates and momenta generators.
It leads to the phase space of the Snyder model. Further, the extended Snyder
algebra is constructed by using the Lorentz algebra, in one dimension higher.
The dual pair of extended Snyder algebra and extended Snyder group is then
formulated. Two Heisenberg doubles are considered, one with the conjugate
tensorial momenta and another with the Lorentz matrices. Explicit formulae for
all Heisenberg doubles are given.",2101.02512v3
2012-05-02,Does Lorentz Force Law Contradict the Principle and Theories of Relativity for Uniform Linear Motion?,"I show that no force or torque is generated in cases involving a charge and a
magnet with their relative velocity zero, in any inertial frame of reference. A
recent suspicion of an anomalous torque and conflict with relativity in this
case is rested. What is distilled as `Lorentz force' in standard
electrodynamics, with relative velocity as the parameter, is an
under-representation of two distinct physical phenomena, an effect due to
Lorentz contraction and another due to the Ampere current-current interaction,
rolled into one due to prejudice from special relativity applied only to linear
motion. When both are included in the analysis of the problem there is no
anomalous force or torque, ensuring the validity of Poincare's principle of
relativity. The issue of validity of electrodynamics without the concept of
absolute rest, however, is subtle and empirically open when general noninertial
motion is considered, as I will discuss in another paper.",1205.1080v2
2012-05-04,"Comment on ""Trouble with the Lorentz law of force: Incompatibility with special relativity and momentum conservation""","It has been recently argued that the Lorentz force is incompatible with
Special Relativity and should be amended in the presence of magnetization and
polarization in order to avoid a paradox involving a magnet in the presence of
an electric field. Here we stress the well-known fact among relativists that
such an incompatibility is simply impossible and show that the appearance of
such a ""paradox"" is a mere consequence of not fully considering the
relativistic consequences of the covariant form of the Lorentz force. It should
be mentioned, though, that this criticism does not invalidate the debate on
which is the law of force followed by Nature, which is an experimental issue.",1205.1502v2
2017-05-01,Special Relativity (Lorentz Transformation) Follows from the Definition of Inertial Frames,"Besides the defining space-time symmetries (homogeneity and isotropy) of
inertial frames, the derivation of Lorentz transformation requires postulating
the principle of relativity and the existence of a finite speed limit. In this
article, we point out that the existence of a finite speed limit can be readily
inferred from the nature of allowed inertial frames. We also show that the
principle of relativity can be obtained from the defining space-time symmetries
of every inertial frame. Therefore, if the conventional definition of inertial
frames is augmented properly, the special theory of relativity (Lorentz
transformation) would follow from the definition of inertial frames.",1705.00505v2
2017-05-14,Acoustic superradiance in a slightly viscous fluid,"The acoustic analogue of the geometry of curved spacetime realised in a
classical fluid becomes Lorentz violating in the presence of viscosity. We
study how this effective Lorentz violation affects acoustic superradiance from
the ergosphere of a rotating sonic black hole formed in such a fluid. It turns
out that Lorentz violation imposes an upper bound on frequencies of acoustic
perturbations that can get scattered from the ergosphere. Incidentally, this
upper bound is same as that on the spectrum of superradiant frequencies. This
study also reveals how superradiance is in general modified when the wave
propagates through a dispersive and dissipative medium. Our result is valid
only upto linear order in the coefficient of viscosity and is thus a first
approximation to the full solution, focussing on the key qualitative features.",1705.04935v1
2017-05-18,Local Lorentz covariance in finite-dimensional Local Quantum Physics,"We show that local Lorentz covariance arises canonically as the group of
transformations between local thermal states in the framework of Local Quantum
Physics, given the following three postulates: (i) Local observable algebras
are finite-dimensional. (ii) Minimal local observable algebras are isomorphic
to $\mathbb{M}_2(\mathbb{C})$, the observable algebra of a single qubit. (iii)
The vacuum restricted to any minimal local observable algebra is a
non-maximally mixed thermal state. The derivation reveals a new and surprising
relation between spacetime structure and local quantum states. In particular,
we show how local restrictions of the vacuum can determine the connection
between different local inertial reference frames.",1705.06711v3
2017-05-26,Seismic sensitivity of Normal-mode Coupling to Lorentz stresses in the Sun,"Understanding the governing mechanism of solar magnetism remains an
outstanding challenge in astrophysics. Seismology is the most compelling
technique with which to infer the internal properties of the Sun and stars.
Waves in the Sun, nominally acoustic, are sensitive to the emergence and
cyclical strengthening of magnetic field, evidenced by measured changes in
resonant oscillation frequencies that are correlated with the solar cycle. The
inference of internal Lorentz stresses from these measurements has the
potential to significantly advance our appreciation of the dynamo. Indeed,
seismological inverse theory for the Sun is well understood for perturbations
in composition, thermal structure and flows but, is not fully developed for
magnetism, owing to the complexity of the ideal magnetohydrodynamic (MHD)
equation. Invoking first-Born perturbation theory to characterize departures
from spherically symmetric hydrostatic models of the Sun and applying the
notation of generalized spherical harmonics, we calculate sensitivity functions
of seismic measurements to the general time-varying Lorentz stress tensor. We
find that eigenstates of isotropic (i.e. acoustic only) background models are
dominantly sensitive to isotropic deviations in the stress tensor and much more
weakly so to anisotropic stresses (and therefore challenging to infer). The
apple cannot fall far from the tree.",1705.09431v2
2017-05-31,"Lorentz Structure of Vector Part of Matrix Elements of Transitions n <-> p, Caused by Strong Low-Energy Interactions and Hypothesis of Conservation of Charged Vector Current","We analyse the Lorentz structure of the matrix elements of the transitions
""neutron <-->proton"", induced by the charged hadronic vector current. We show
that the term maintaining conservation of the charged hadronic vector current
even for different masses of the neutron and proton (see T. Leitner et al.,
Phys. Rev. C 73, 065502 (2006) and A. M. Ankowski, arXiv:1601.06169 [hep-ph])
has a dynamical origin, related to the G-even first class current contribution.
We show that because of invariance of strong low-energy interactions under the
G-parity transformations, the G-odd contribution with the Lorentz structure
$q_{\mu}$, where $q_{\mu}$ is a momentum transferred, does not appear in the
matrix elements of the ``neutron <-> proton' transitions.",1705.11102v2
2017-09-24,Effects of Lorentz invariance violation on cosmic ray photon emission and gamma ray decay processes,"In this work, we use Lorentz invariance violation (LIV) introduced as a
generic modification to particle dispersion relations to study some
consequences of single photon emission, known as vacuum Cherenkov radiation,
and photon decay processes in cosmic and gamma rays. These processes are
forbidden in a Lorentz invariant theory but allowed under the hypothesis of
LIV. We show that the emission rate have a dependency on the cosmic ray primary
mass and the electric charge that could modify the UHECR spectrum. Furthermore,
LIV dramatically enhances photon decay into an electro-positron pair above
certain energy threshold. This last effect can then be used to set limits to
the LIV energy scale from the direct observation of very high energy cosmic
photon events by telescopes of gamma-rays.",1709.08247v1
2017-11-10,Equivalent and attained version of Hardy's inequality in $\mathbb{R}^n$,"We investigate connections between Hardy's inequality in the whole space
$\mathbb{R}^n$ and embedding inequalities for Sobolev-Lorentz spaces. In
particular, we complete previous results due to [A. Alvino, Sulla
diseguaglianza di Sobolev in spazi di Lorentz, (1977)] and [G. Talenti, An
inequality between $u^*$ and $|{\rm{grad}} u^*|$, (1992)] by establishing
optimal embedding inequalities for the Sobolev-Lorentz quasinorm
$\|\nabla\,\cdot\,\|_{p,q}$ also in the range $p < q<\infty$, which remained
essentially open since the work of Alvino. Attainability of the best embedding
constants is also studied, as well as the limiting case when $q=\infty$. Here,
we surprisingly discover that the Hardy inequality is equivalent to the
corresponding Sobolev-Marcinkiewicz embedding inequality. Moreover, the latter
turns out to be attained by the so-called ""ghost"" extremal functions of
[Brezis-V\'azquez, Blow-up solutions of some nonlinear elliptic problems,
(1977)], in striking contrast with the Hardy inequality, which is never
attained. In this sense, our functional approach seems to be more natural than
the classical Sobolev setting, answering a question raised by Brezis and
V\'azquez.",1711.03763v1
2018-03-05,Convergence in nonlinear laser wakefield accelerators modeling in a Lorentz-boosted frame,"Laser wakefield acceleration modeling using the Lorentz-boosted frame
technique in the particle-in-cell code has demonstrated orders of magnitude
speedups. A convergence study was previously conducted in cases with external
injection in the linear regime and without injection in the nonlinear regime,
and the obtained results have shown a convergence within the percentage level.
In this article, a convergence study is carried out to model electron
self-injection in the 2-1/2D configuration. It is observed that the
Lorentz-boosted frame technique is capable of modeling complex particle
dynamics with a significant speedup. This result is crucial to curtail the
computational time of the modeling of future chains of $10\,\mathrm{GeV}$ laser
wakefield accelerator stages with high accuracy.",1803.01890v1
2018-03-15,Looking at spacetime atoms from within the Lorentz sector,"Recently, a proposal has been made to figure out the expected discrete nature
of spacetime at the smallest scales in terms of atoms of spacetime, capturing
their effects through a scalar $\rho$, function of the point $P$ and the vector
$v^a$ at $P$, expressing their density. This has been done in the Euclideanized
space one obtains through analytic continuation from Lorentzian sector at $P$.
$\rho$ is defined in terms of a peculiar `effective' metric $q_{ab}$, also
recently introduced, which stems from a careful request that $q_{ab}$ coincides
with $g_{ab}$ at large (space/time) distances, but gives finite distance in the
coincidence limit.
  This work reports on an attempt to introduce a definition of $\rho$ directly
in the Lorentz sector. This turns out to be not a so trivial task, essentially
because of the null case, i.e. when $v^a$ is null, as in this case we lack even
a concept of $q_{ab}$. A notion for $q_{ab}$ in the null case is here proposed
and an expression for it is derived. In terms of it, an expression for $\rho$
can be derived, which turns out to coincide with what obtained from analytic
continuation. This, joined with the consideration of timelike/spacelike cases,
potentially completes a description of $q_{ab}$ and $\rho$ within Lorentz
spacetimes.",1803.05726v1
2018-06-07,Gravity as a Yang-Mills Theory Based on the Lorentz Group,"The Yang-Mills theory associated with the restricted Lorentz group is
revisited as a candidate for a theory of gravity. This is a natural idea
because the principle of equivalence of gravitation and inertia suggests to
introduce locally inertial coordinate systems with the gauge freedom of Lorentz
transformations. Compared to previous implementations of the idea, we use a
generalized expression for the vector potential of the gauge theory in terms of
the metric, which involves a coupling constant. One can verify that, in the
limit of small coupling constant, all the classical predictions of general
relativity are reproduced. For the resulting higher-order field equations, the
nature of the singularity associated with black holes changes. The proposed
theory is based on a dimensionless action for coupling the Yang-Mills field to
matter.",1806.02765v2
2018-06-15,Relations dependent on new fundamental constants among spacetime observables of quantum particle,"Generators of spacetime translations and Lorentz group transformations form
the Lie algebra of the Poincar\'e group and give rise to the Casimir invariants
for a specification of elementary particle characteristics. Moreover quantum
operators of coordinate and momentum components of a particle in Minkowski
spacetime together with Lorentz group generators belong to the known
noncommutative algebra. This algebra can be generalized under some constraints,
in particular, the Lorentz invariance condition. The generalized algebra
depends on the new fundamental constants with dimensions of length (L), mass
(M) and action (H). Quantum fields, which can be constructed with the help of
representations of this algebra, are referred to as HLM generalized quantum
fields and the associated particles as HLM quantum particles. Relations between
spacetime observables of a HLM quantum particle depend on the new constants and
lead to complication of the Poincar\'e invariant equations for canonical
fields. The modification of a quantum measurement procedure is needed in order
to take into account inherent features of HLM quantum particles.",1806.06707v1
2018-06-21,Lorentz-violating dimension-five operator contribution to the black body radiation,"We investigate the thermodynamics of a photon gas in an effective field
theory model that describes Lorentz violations through dimension-five operators
and Horava-Lifshitz theory. We explore the electrodynamics of the model which
includes higher order derivatives in the Lagrangian that can modify the
dispersion relation for the propagation of the photons. We shall focus on the
deformed black body radiation spectrum and modified Stefan-Boltzmann law to
address the allowed bounds on the Lorentz-violating parameter.",1806.08273v2
2018-06-24,Field-free electrodynamics,"The Maxwell-Lorentz theory of electrodynamics cannot readily be applied to a
system of point charges: the electromagnetic field is not well-defined at the
position of a point charge, an energy conservation argument is not obvious, an
infinite regression arises when the interactions occur along the light cones
and the advanced potentials lead to an apparent breakdown of causality. A
rather controversial solution to these problems involves instantaneous action
at a distance, which comes at the expense of violating Lorentz covariance. Some
experiments call into question the applicability of the standard retardation
constraint to all components of the electromagnetic field. In light of these
experimental results, this paper develops two instantaneous action at a
distance theories of electrodynamics, which are compatible with some basic
features of classical electrodynamics: the Lorentz transformed Coulomb's law,
the Biot-Savart force law and Faraday's law of induction.",1806.10082v10
2018-07-02,Consistency of an alternative CPT-odd and Lorentz-violating extension of QED,"We investigate an alternative CPT-odd Lorentz-breaking QED which includes the
Carroll-Field-Jackiw (CFJ) term of the Standard Model Extension (SME), writing
the gauge sector in the action in a Palatini-like form, in which the vectorial
field and the field-strength tensor are treated as independent entities.
Interestingly, this naturally induces a Lorentz-violating mass term in the
classical action. We study physical consistency aspects of the model both at
classical and quantum levels.",1807.00904v3
2018-07-16,Effect of strength of gravitational field on electrode processes,"Relativistic transformation of electrode potential has been derived to
explain time dilation in electrode processes. The newly formulated Lorentz
transformation of the electrode potential is explained in terms of the
generation of spin 2-boson gravitons from the fusion of spin-1 boson
virtual-photons followed by their eventual escape in higher dimensions.
Gravitational transformations of electrode potential have also been derived
that explains decrease in the cell potential at the lower gravitational field.
The dropping of electrode potential at the lower gravitational field is also
explained in terms of the greater flux of gravitons escaping into higher
dimensions at lower gravitational fields than at higher gravitational fields.
Similarly potential energy associated with the spin of magnetically active
nuclei in applied magnetic field within NMR spectrometer has been shown to be
Lorentz variant that mathematically proves Hamiltonian describing the energy of
magnetically active nuclei to be Lorentz variant. Relativistic and
gravitational transformations of electrode potential and potential energy of
magnetically active nuclei under applied magnetic field are shown analogous to
one another.",1808.09350v3
2018-12-03,Extra equation of gravity induced by spontaneous local Lorentz symmetry breakdown,"A model of spontaneous Lorentz violation in four dimension is given, which
seems to provide a Lorentz invariant effective theory. An SU(2) Yang-Mills
gauge field and an auxiliary U(1) vector field generate gravity and other
interactions when they have vacuum expectation values. The emergent gravity is
equivalent to conventional general relativity up to the third order terms in
the Lagrangian. The coupling to matter, including spin-1/2 fermions, is also
given correctly to this level. It remains to be seen whether this formalism
reproduces the properties of black holes and other consequences obtained from
Einstein's theory.",1812.02557v5
2018-12-13,Fermionic Casimir effect in a field theory model with Lorentz symmetry violation,"In this paper, we evaluate the Casimir energy and pressure for a massive
fermionic field confined in the region between two parallel plates. In order to
implement this confinement we impose the standard MIT bag boundary on the
plates for the fermionic field. In this paper we consider a quantum field
theory model with a CPT even, aether-like Lorentz symmetry violation. It turns
out that the fermionic Casimir energy and pressure depend on the direction of
the constant vector that implements the Lorentz symmetry breaking.",1812.05428v3
2018-12-23,Lorentz Boost Networks: Autonomous Physics-Inspired Feature Engineering,"We present a two-stage neural network architecture that enables a fully
autonomous and comprehensive characterization of collision events by
exclusively exploiting the four momenta of final-state particles. We refer to
the first stage of the architecture as Lorentz Boost Network (LBN). The LBN
allows the creation of particle combinations representing rest frames. The LBN
also enables the formation of further composite particles, which are then
transformed into said rest frames by Lorentz transformation. The properties of
the composite, transformed particles are compiled in the form of characteristic
variables that serve as input for a subsequent network. This second network has
to be configured for a specific analysis task such as the separation of signal
and background events. Using the example of the classification of ttH and ttbb
events, we compare the separation power of the LBN approach with that of
domain-unspecific deep neural networks (DNN). We observe leading performance
with the LBN, even though we provide the DNNs with extensive additional input
information beyond the particle four momenta. Furthermore, we demonstrate that
the LBN forms physically meaningful particle combinations and autonomously
generates suitable characteristic variables.",1812.09722v1
2018-12-28,Combined Search for a Lorentz-Violating Force in Short-Range Gravity Varying as the Inverse Sixth Power of Distance,"Precision measurements of the inverse-square law via experiments on
short-range gravity provide sensitive tests of Lorentz symmetry. A combined
analysis of data from experiments at the Huazhong University of Science and
Technology and Indiana University sets simultaneous limits on all 22
coefficients for Lorentz violation correcting the Newton force law as the
inverse sixth power of distance. Results are consistent with no effect at the
level of $10^{-12}$ m$^{4}$.",1812.11123v1
2019-02-14,Invariant temperature of a moving body,"The temperature of a mechanical body has a kinetic interpretation: it
describes the relative motion of particles within the body. Since the relative
velocity of two particles is a Lorentz invariant, so is the temperature. In
statistical physics, the temperature is defined as the inverse of the partial
derivative of the entropy with respect to the internal energy (the energy in
the rest frame of reference). Since the internal energy is a Lorentz invariant,
so is the temperature. The Lorentz invariance of the temperature is a
consequence of the symmetry between two bodies with equal proper temperatures,
moving relative to one another with a constant relative speed, and in thermal
contact. We give an equivalent, covariant definition of the temperature in
terms of the energy and momentum of the body. We also note contradictions in
the earlier articles that derived various transformation laws for the internal
energy and temperature.",1902.05536v1
2019-02-26,Extension of positivity bounds to non-local theories: IR obstructions to Lorentz invariant UV completions,"We derive positivity bounds on low energy effective field theories which
admit gapped, analytic, unitary, Lorentz invariant, and possibly non-local UV
completions, by considering 2 to 2 scatterings of Jaffe fields whose
Lehmann-K\""{a}ll\'{e}n spectral density can grow exponentially. Several
properties of S-matrix, such as analyticity properties, are assumed in our
derivation. Interestingly, we find that some of the positivity bounds obtained
in the literature, such as sub-leading order forward-limit bounds, must be
satisfied even when UV completions fall into non-localizable theories in
Jaffe's language, unless momentum space Wightman functions grow too rapidly at
high energy. Under this restriction on the growth rate, such bounds may provide
IR obstructions to analytic, unitary, and Lorentz invariant UV completions.",1902.10039v3
2019-02-27,Dynamical Lorentz symmetry breaking in a tensor bumblebee model,"In this paper, we formulate a theory of the second-rank antisymmetric
(pseudo)tensor field minimally coupled to a spinor, calculate the one-loop
effective potential of the (pseudo)tensor field, and, explicitly, demonstrate
that it is positively defined and possesses a continuous set of minima, both
for tensor and pseudotensor cases. Therefore, our model turns out to display
the dynamical Lorentz symmetry breaking. We also argue that, contrarily to the
derivative coupling we use here, derivative-free couplings of the antisymmetric
tensor field to a spinor do not generate the positively defined potential and
thus do not allow for the dynamical Lorentz symmetry breaking.",1902.10592v2
2019-03-14,Singular Hamiltonians in models with spontaneous Lorentz symmetry breaking,"Many current models which ""violate Lorentz symmetry"" do so via a vector or
tensor field which takes on a vacuum expectation value, thereby spontaneously
breaking the underlying Lorentz symmetry of the Lagrangian. One common way to
construct such a model is to posit a smooth potential for this field; the
natural low-energy solution of such a model would then be excepted to have the
tensor field near the minimum of its potential. It is shown in this work that
some such models, while appearing well-posed at the level of the Lagrangian,
have a Hamiltonian which is singular on the vacuum manifold and are therefore
ill-posed. I illustrate this pathology for an antisymmetric rank-2 tensor
field, and find sufficient conditions under which this pathology occurs for
more general field theories.",1903.06140v1
2019-03-21,Some new results related to Lorentz G-gamma spaces and interpolation,"We compute the K-functional related to some couple of spaces as small or
classical Lebesgue space or Lorentz-Marcinkiewicz spaces completing the results
of the previous works of the authors. This computation allows to determine the
interpolation space in the sense of Peetre for such couple. It happens that the
result is always a G-gamma space, since this last space covers many spaces. The
motivations of such study are various, among them we wish to obtain a
regularity estimate for the so called very weak solution of linear equation in
a domain Omega with data in the space of the integrable function with respect
to the distance function to the boundary of Omega.",1903.09118v3
2019-04-08,Quantum-corrected rotating acoustic black holes in Lorentz-violating background,"In this paper we explore the effect of the generalized uncertainty principle
and modified dispersion relation to compute Hawking radiation from a rotating
acoustic black hole in the tunneling formalism by using the
Wentzel-Kramers-Brillouin (WKB) approximation applied to the Hamilton-Jacobi
method. The starting point is to consider the planar acoustic black hole metric
found in a Lorentz-violating Abelian Higgs model. In our analyzes we
investigate quantum corrections for the Hawking temperature and entropy. A
logarithmic correction and an extra term that depends on a conserved charge
were obtained. We also have found that the changing in the Hawking temperature
${\cal T}_H$ for a dispersive medium due to a Lorentz-violating background
accounts for supersonic velocities in the general form $(v_g-v_p)/v_p = \Delta
{\cal T}_H/{\cal T}_H\sim10^{-5}$ in Bose-Einstein-Condensate (BEC) systems.",1904.04229v2
2019-04-17,Improvement of the Bernstein-type theorem for space-like zero mean curvature graphs in Lorentz-Minkowski space using fluid mechanical duality,"Calabi's Bernstein-type theorem asserts that a zero mean curvature entire
graph in Lorentz-Minkowski space $\boldsymbol L^3$ which admits only space-like
points is a space-like plane. Using the fluid mechanical duality between
minimal surfaces in Euclidean 3-space $\boldsymbol E^3$ and maximal surfaces in
Lorentz-Minkowski space $\boldsymbol L^3$, we give an improvement of this
Bernstein-type theorem. More precisely, we show that a zero mean curvature
entire graph in $\boldsymbol L^3$ which does not admit time-like points
(namely, a graph consists of only space-like and light-like points) is a plane.",1904.08046v2
2019-04-18,Equivariant mappings and invariant sets on Minkowski space,"In this paper we introduce the systematic study of invariant functions and
equivariant mappings defined on Minkowski space under the action of the Lorentz
group. We adapt some known results from the orthogonal group acting on the
Euclidean space to the Lorentz group acting on the Minkowski space. In
addition, an algorithm is given to compute generators of the ring of functions
that are invariant under an important class of Lorentz subgroups, namely when
these are generated by involutions, which is also useful to compute
equivariants. Furthermore, general results on invariant subspaces of the
Minkowski space are presented, with a characterization of invariant lines and
planes in the two lowest dimensions.",1904.09001v2
2019-08-06,Infinite horizon billiards: Transport at the border between Gauss and Lévy universality classes,"We consider transport in two billiard models, the infinite horizon Lorentz
gas and the stadium channel, presenting analytical results for the spreading
packet of particles. We first obtain the cumulative distribution function of
traveling times between collisions, which exhibits non-analytical behavior.
Using a renewal assumption and the L\'evy walk model, we obtain the particles'
probability density. For the Lorentz gas, it shows a distinguished difference
when compared with the known Gaussian propagator, as the latter is valid only
for extremely long times. In particular, we show plumes of particles spreading
along the infinite corridors, creating power-law tails of the density. We
demonstrate the slow convergence rate via summation of independent identically
distributed random variables on the border between L\'evy and Gauss laws. The
renewal assumption works well for the Lorentz gas with intermediately sized
scattering centers, but fails for the stadium channel due to strong temporal
correlations. Our analytical results are supported with numerical samplings.",1908.02053v2
2019-08-07,A soft-photon theorem for the Maxwell-Lorentz system,"For the coupled system of classical Maxwell-Lorentz equations we show that
the quantities \begin{equation*}
  \mathfrak{F}(\hat x, t)=\lim_{|x|\to \infty} |x|^2 F(x,t), \quad
\mathcal{F}(\hat k, t)=\lim_{|k|\to 0} |k| \widehat{F}(k,t), \end{equation*}
where $F$ is the Faraday tensor, $\hat{F}$ its Fourier transform in space and
$\hat{x}:=\frac{x}{|x|}$, are independent of $t$. We combine this observation
with the scattering theory for the Maxwell-Lorentz system due to Komech and
Spohn, which gives the asymptotic decoupling of $F$ into the scattered
radiation $F_{\mathrm{sc},\pm}$ and the soliton field $F_{v_{\pm\infty}}$
depending on the asymptotic velocity $v_{\pm\infty}$ of the electron at large
positive (+), resp. negative (-) times. This gives a soft-photon theorem of the
form \begin{equation*} \mathcal{F}_{\text{sc},+}(\hat{k}) -
\mathcal{F}_{\text{sc},-}(\hat{k})= -(
\mathcal{F}_{v_{+\infty}}(\hat{k})-\mathcal{F}_{v_{-\infty}}(\hat{k})),
\end{equation*} and analogously for $\mathfrak{F}$, which links the
low-frequency part of the scattered radiation to the change of the electron's
velocity. Implications for the infrared problem in QED are discussed in the
Conclusions.",1908.02615v1
2019-08-11,Geometry of weighted Lorentz-Finsler manifolds I: Singularity theorems,"We develop the theory of weighted Ricci curvature in a weighted
Lorentz-Finsler framework and extend the classical singularity theorems of
general relativity. In order to reach this result, we generalize the Jacobi,
Riccati and Raychaudhuri equations to weighted Finsler spacetimes and study
their implications for the existence of conjugate points along causal
geodesics. We also show a weighted Lorentz-Finsler version of the Bonnet-Myers
theorem based on a generalized Bishop inequality.",1908.03832v3
2019-08-12,Variable jet Lorentz factors can explain soft self-absorbed radio spectra of accreting black-holes,"We study the effect of variable jet bulk Lorentz factors, i.e., either jet
acceleration or deceleration, on partially synchrotron self-absorbed radio
spectra from cores of radio-loud active galactic nuclei and black-hole binaries
in the hard state. In about a half of quasars and radio galaxies, their core
radio spectra are observed to be soft, i.e., have the spectral index of
$\alpha<0$. If they are emitted by jets with constant Lorentz factors, that
softness implies deposition of large amounts of energy at large distances from
the centre. We show here that such soft spectra can be explained without that
energetic requirement by emission of jets with the Doppler factor increasing
with the distance. This can happen for either jet acceleration or deceleration,
depending on the jet viewing angle. We find our model can explain the quiescent
radio to X-ray spectra of the BL Lac objects Mrk 421 and Mrk 501.",1908.04216v1
2019-11-05,Role of Quantum Optics in Synthesizing Quantum Mechanics and Relativity,"Two-photon states produce enough symmetry needed for Dirac's construction of
the two-oscillator system which produces the Lie algebra for the O(3,2)
space-time symmetry. This O(3,2) group can be contracted to the inhomogeneous
Lorentz group which, according to Dirac, serves as the basic space-time
symmetry for quantum mechanics in the Lorentz-covariant world. Since the
harmonic oscillator serves as the language of Heisenberg's uncertainty
relations, it is right to say that the symmetry of the Lorentz-covariant world,
with Einstein's $E = mc^2$, is derivable from Heisenberg's uncertainty
relations.",1911.01642v2
2019-11-05,A novel test of Lorentz violation in the photon sector with an LC circuit,"In the presence of an external magnetic field, the Carroll-Field-Jackiw term
introduces a displacement current proportional to the Lorentz-violating
background that induces a time-dependent magnetic field. Axion-like particles
or hidden photons could generate an analogous signal, potentially detectable
with the set-up suggested by Sikivie, Tanner and Sullivan - a sensitive
magnetometer coupled to a superconducting LC circuit. We show that a similar
set-up, but with an externally driven pick-up loop whose area varies
harmonically at $\sim$ Hz, can be used to probe the spatial components of the
Lorentz-violating background to the level of $\lesssim 10^{-31}$ GeV. This is
eight orders of magnitude more sensitive than previous laboratory-based limits.",1911.01990v3
2019-12-04,Sharp Hardy space estimates for multipliers,"We provide an improvement of Calder\'on and Torchinsky's version of the
H\""ormander multiplier theorem on Hardy spaces $H^p$ ($0<p<\infty$), by
replacing the Sobolev space $L_s^2(A_0)$ by the Lorentz-Sobolev space
$L_s^{\tau^{(s,p)} ,\min(1,p) }(A_0)$, where $\tau^{(s,p)}
=\frac{n}{s-(n/\min{(1,p)}-n)}$ and $A_0$ is the annulus $\{\xi \in
\mathbb{R}^n: 1/2<|\xi|<2\}$. Our theorem also extends that of Grafakos and
Slav\'ikov\'a to the range $0<p\le 1$. Our result is sharp in the sense that
the preceding Lorentz-Sobolev space cannot be replaced by a smaller
Lorentz-Sobolev space $L^{r,q}_s(A_0)$ with $r< \tau^{(s,p)} $ or
$q>\min(1,p)$.",1912.01749v3
2019-12-10,Manifestly Lorentz invariant chiral boson action,"A manifestly Lorentz invariant action is found for the Floreanini-Jackiw
chiral boson. The method involves a novel chiral reduction of the phase-space
action for a string, and can be adapted to describe chiral bosons on the
heterotic string worldsheet. A similar manifestly Lorentz invariant action is
found for an entire class of conformal chiral 2k-form electrodynamics in (4k+2)
dimensions which includes the Floreanini-Jackiw theory as the k=0$ case.",1912.04773v5
2020-03-05,"Generalized Heisenberg algebra applied to realizations of the orthogonal, Lorentz and Poincare algebras and their dual extensions","We introduce the generalized Heisenberg algebra $\mathcal{H}_n$ and construct
realizations of the orthogonal and Lorentz algebras by power series in a
semicompletion of $\mathcal{H}_n$. The obtained realizations are given in terms
of the generating functions for the Bernoulli numbers. We also introduce an
extension of the orthogonal and Lorentz algebras by quantum angles and study
realizations of the extended algebras in $\mathcal{H}_n$. Furthermore, we show
that by extending the generalized Heisenberg algebra $\mathcal{H}_n$ one can
also obtain realizations of the Poincare algebra and its extension by quantum
angles.",2003.02726v3
2020-03-07,Lorentz Invariant Quantum Concurrence for SU(2) x SU(2) spin-parity states,"The quantum concurrence of $SU(2) \otimes SU(2)$ spin-parity states is shown
to be invariant under $SO(1,3)$ Lorentz boosts and $O(3)$ rotations when the
density matrices are constructed in consonance with the covariant probabilistic
distribution of Dirac massive particles. Similar invariance properties are
obtained for the quantum purity and for the trace of unipotent density matrix
operators. The reported invariance features -- obtained in the scope of the
$SU(2) \otimes SU(2)$ corresponding to just one of the inequivalent
representations enclosed by the $SL(2,\mathbb{C})\otimes SL(2,\mathbb{C})$
symmetry -- set a more universal and kinematical-independent meaning for the
quantum entanglement encoded in systems containing not only information about
spin polarization but also the correlated information about intrinsic parity.
Such a covariant framework is used for computing the Lorentz invariant
spin-parity entanglement of spinorial particles coupled to a magnetic field,
through which the extensions to more general Poincar\'e classes of spinor
interactions are straightforwardly depicted.",2003.03641v1
2020-03-25,Diffusive photospheres in gamma-ray bursts,"Photospheric emission may originate from relativistic outflows in two
qualitatively different regimes:\ last scattering of photons inside the outflow
at the photospheric radius, or radiative diffusion to the boundary of the
outflow. In this work the measurement of temperature and flux of the thermal
component in the early afterglows of several gamma-ray bursts (GRBs) along with
the total flux in the prompt phase are used to determine initial radii of the
outflow as well as its Lorentz factors. Results indicate that in some cases the
outflow has relatively low Lorentz factors $\Gamma<10$, favouring cocoon
interpretation, while in other cases Lorentz factors are larger $\Gamma>10$,
indicating diffusive photospheric origin of the thermal component, associated
with an ultrarelativistic outflow.",2003.11440v1
2020-05-03,The multilinear Hormander multiplier theorem with a Lorentz-Sobolev condition,"In this article, we provide a multilinear version of the H\""ormander
multiplier theorem with a Lorentz-Sobolev space condition. The work is
motivated by the recent result of the first author and Slav\'ikov\'a where an
analogous version of classical H\""ormander multiplier theorem was obtained;
this version is sharp in many ways and reduces the number of indices that
appear in the statement of the theorem. As a natural extension of the linear
case, in this work, we prove that if $mn/2<s<mn$, then $$ \big\Vert
T_{\sigma}(f_1,\dots,f_m)\big\Vert_{L^p((\mathbb{R})^n)}\lesssim
\sup_{k\in\mathbb{Z}}\big\Vert
\sigma(2^k\;\vec{\cdot}\;)\widehat{\Psi^{(m)}}\big\Vert_{L_{s}^{mn/s,1}(\mathbb{R}^{mn})}\Vert
f_1\Vert_{L^{p_1}((\mathbb{R})^n)}\cdots \Vert
f_m\Vert_{L^{p_m}((\mathbb{R})^n)} $$
  for certain $p,p_1,\dots,p_m$ with $1/p=1/p_1+\dots+1/p_m$. We also show that
the above estimate is sharp, in the sense that the Lorentz-Sobolev space
$L_s^{mn/s,1}$ cannot be replaced by $L_{s}^{r,q}$ for $r<mn/s$, $0<q\leq
\infty$, or by $L_s^{mn/s,q}$ for $q>1$.",2005.01213v1
2020-05-05,Inflation in Motion: Unitarity Constraints in Effective Field Theories with Broken Lorentz Symmetry,"During inflation, there is a preferred reference frame in which the expansion
of the background spacetime is spatially isotropic. In contrast to Minkowski
spacetime, observables can depend on the velocity of the system with respect to
this cosmic rest frame. We derive new constraints from radiative stability and
unitarity on effective field theories with such spontaneously broken Lorentz
symmetry. In addition to a maximum energy scale, there is now also a critical
velocity at which the theory breaks down. The theory therefore has different
resolving power in time and in space, and we show that these can only coincide
if cubic Lorentz-violating interactions are absent. Applying these bounds to
the Effective Field Theory of Inflation, we identify the region of parameter
space in which inflation can be both single-field and weakly coupled on
subhorizon scales. This can be implemented as a theoretical prior, and we
illustrate this explicitly using Planck observational constraints on the
primordial bispectrum.",2005.02366v2
2020-05-19,Casimir energy and topological mass for a massive scalar field with Lorentz violation,"A Lorentz symmetry violation aether-type theoretical model is considered to
investigate the Casimir effect and the generation of topological mass
associated with a self-interacting massive scalar fields obeying Dirichlet,
Newman and mixed boundary conditions on two large and parallel plates. By
adopting the path integral approach we found the effective potential at one-
and two-loop corrections which provides both the energy density and topological
mass when taken in the ground state of the scalar field. We then analyse how
these quantities are affected by the Lorentz symmetry violation and compare the
results with previous ones found in literature.",2005.09513v3
2020-05-30,Radiative Correction to the Casimir Energy for Lorentz-violating Scalar Field in d+1 Dimensions,"The renormalization program in every renormalized theory should be run
consistently with the type of boundary condition imposed on quantum fields. To
maintain this consistency, the counterterms usually appear in the
position-dependent form. In the present study, using such counterterms, we
calculated the radiative correction to the Casimir energy for massive and
massless Lorentz-violating scalar field constrained with Dirichlet boundary
condition between two parallel plates in d spatial dimensions. In the
calculation procedure, to remove infinities appearing in the vacuum energies,
the box subtraction scheme supplemented by the cutoff regularization technique
and analytic continuation technique were employed. Normally, in the box
subtraction scheme, two similar configurations are defined and their vacuum
energies are subtracted from each other in the appropriate limits. Our final
results regarding all spatial dimensions were convergent and consistent with
the expected physical basis. We further plotted the Casimir energy density for
the time-like and space-like Lorentz-violating systems in a number of odd and
even dimensions; multiple aspects of the obtained results were ultimately
discussed.",2006.00299v1
2020-06-04,Anomalous transport in the soft-sphere Lorentz model,"The sensitivity of anomalous transport in crowded media to the form of the
inter-particle interactions is investigated through computer simulations. We
extend the highly simplified Lorentz model towards realistic natural systems by
modeling the interactions between the tracer and the obstacles with a smooth
potential. We find that the anomalous transport at the critical point happens
to be governed by the same universal exponent as for hard exclusion
interactions, although the mechanism of how narrow channels are probed is
rather different. The scaling behavior of simulations close to the critical
point confirm this exponent. Our result indicates that the simple Lorentz model
may be applicable to describing the fundamental properties of long-range
transport in real crowded environments.",2006.02714v1
2020-06-08,Lorentz Group Equivariant Neural Network for Particle Physics,"We present a neural network architecture that is fully equivariant with
respect to transformations under the Lorentz group, a fundamental symmetry of
space and time in physics. The architecture is based on the theory of the
finite-dimensional representations of the Lorentz group and the equivariant
nonlinearity involves the tensor product. For classification tasks in particle
physics, we demonstrate that such an equivariant architecture leads to
drastically simpler models that have relatively few learnable parameters and
are much more physically interpretable than leading approaches that use CNNs
and point cloud approaches. The competitive performance of the network is
demonstrated on a public classification dataset [27] for tagging top quark
decays given energy-momenta of jet constituents produced in proton-proton
collisions.",2006.04780v1
2020-09-14,Kant and Hegel in Physics,"Kant and Hegel are among the philosophers who are guiding the way in which we
reason these days. It is thus of interest to see how physical theories have
been developed along the line of Kant and Hegel. Einstein became interested in
how things appear to moving observers. Quantum mechanics is also an
observer-dependent science. The question then is whether quantum mechanics and
relativity can be synthesized into one science. The present form of quantum
field theory is a case in point. This theory however is based on the algorithm
of the scattering matrix where all participating particles are free in the
remote past and in the remote future. We thus need, in addition, a
Lorentz-covariant theory of bound state which will address the question of how
the hydrogen atom would look to moving observers. The question is then whether
this Lorentz-covariant theory of bound states can be synthesized with the field
theory into a Lorentz-covariant quantum mechanics. This article reviews the
progress made along this line. This integrated Kant-Hegel process is
illustrated in terms of the way in which Americans practice their democracy.",2009.06198v2
2020-10-13,Particle scattering in a sonic analogue of special relativity,"We investigate a simple toy model of particle scattering in the flat
spacetime limit of an analogue-gravity model. The analogue-gravity medium is
treated as a scalar field of phonons that obeys the Klein-Gordon equation and
thus admits a Lorentz symmetry with respect to $c_\mathrm{s}$, the speed of
sound in the medium. The particle from which the phonons are scattered is
external to the system and does not obey the sonic Lorentz symmetry that the
phonon field obeys. In-universe observers who use the exchange of sound to
operationally measure distance and duration find that the external particle
appears to be a sonically Lorentz-violating particle. By performing a sonic
analogue to Compton scattering, in-universe observers can determine if they are
in motion with respect to their medium. If in-universe observers were then to
correctly postulate the dispersion relation of the external particle, their
velocity with respect to the medium could be found.",2010.06387v2
2020-11-10,Charging in the vortex lattice of type-II superconductors,"We study the magnetic-field dependence of the vortex-core charge in the
Abrikosov lattice of an $s$-wave superconductor based on the augmented
quasiclassical equations, where we incorporate the pair-potential gradient
(PPG) terms characteristic of charging in superconductors besides the
well-known Lorentz force. Our numerical results at $T=0.2 T_{\rm c}$ and $0.5
T_{\rm c}$ reveal that periodic charge redistribution is superimposed on the
magnetic flux-line lattice with different spatial patterns at different fields.
The PPG terms are dominant at weak fields over the Lorentz force for
accumulating charge in the vortex cores, whereas the Lorentz force prevails at
higher fields to give rise to a peak structure in the core charge around $H\sim
\frac{1}{2}H_{{\rm c}2}$. We estimate the peak value of the core charge at
$T=0.2 T_{\rm c}$ using parameters appropriate for cuprates to obtain a large
value of $Q \sim 10^{-2} |e|$ in the core region of radius $0.2 \xi_0$ in the
$ab$ plane and length $1 \ {\rm nm}$ along the $c$ axis.",2011.04856v3
2020-11-11,Subleading BMS Charges and The Lorentz Group,"The extended BMS group includes supertranslation, dual supertranslation and
Lorentz transformations. The generators of these symmetries can be classified
according to their parity into ""electric"" and ""magnetic"" types. Using a
multipole expansion of gravitational sources in the Newman-Penrose formalism,
we associate each one of these charges with a particular moment. At leading
order, the ""electric"" and ""magnetic"" monopole moments correspond respectively
to supertranslations and dual supertranslations. At the first subleading order,
the ""electric"" and ""magnetic"" dipole moments correspond respectively to boosts
and rotations, therefore comprising the entire Lorentz group. Electric-magnetic
type of duality then rotates the boost and rotation generators into each other.",2011.06008v2
2021-02-10,Positivity Bounds without Boosts,"We derive the first positivity bounds for low-energy Effective Field Theories
(EFTs) that are not invariant under Lorentz boosts. ""Positivity bounds"" are the
low-energy manifestation of certain fundamental properties in the UV -- to date
they have been used to constrain a wide variety of EFTs, however since all of
the existing bounds require Lorentz invariance they are not directly applicable
when this symmetry is broken, such as for most cosmological and condensed
matter systems. From the UV axioms of unitarity, causality and locality, we
derive an infinite family of bounds which (derivatives of) the $2\to2$ EFT
scattering amplitude must satisfy even when Lorentz boosts are broken (either
spontaneously or explicitly). We apply these bounds to the leading-order EFT of
both a superfluid and the scalar fluctuations produced during inflation,
comparing in the latter case with the current observational constraints on
primordial non-Gaussianity.",2102.05683v1
2021-02-23,Fermi acceleration in relativistic collisionless plasma shocks correlates with anisotropic energy gains,"Collisionless shocks generated by two colliding relativistic
electron-positron plasma shells are studied using particle-in-cell (PIC)
simulations. Shocks are mediated by the Weibel instability (WI), and the
kinetic energy of the fastest accelerated particles is found to be
anisotropically modified by WI-induced electric fields. Specifically, we show
that all particles interacting with the shock bifurcate into two groups based
on their final relativistic Lorentz factor $\gamma$: slow ($\gamma <
\gamma_{bf}$) and fast ($\gamma > \gamma_{bf}$), where $\gamma_{bf}$ is the
bifurcation Lorentz factor that was found to be approximately twice the initial
(upstream) Lorentz factor $\gamma_0$. We have found that the energies of the
slow particles are equally affected by the longitudinal and transverse
components of the shock electric field, whereas the fast particles are
primarily accelerated by the transverse field component.",2102.11975v2
2021-03-05,Black Hole Superradiance in the Presence of Lorentz Symmetry Violation,"In this paper we consider the massive scalar perturbation on the top of a
small spinning-like black hole in context of Einstein-bumblebee modified
gravity in order to probe the role of spontaneous Lorentz symmetry breaking on
the superradiance scattering and corresponding instability. We show that at the
low-frequency limit of the scalar wave the superradiance scattering will be
enhanced with the Lorentz-violating parameter $\alpha<0$ and will be weakened
with $\alpha>0$. Moreover, by addressing the black hole bomb issue, we extract
an improved bound in the instability regime indicating that $\alpha<0$
increases the parameter space of the scalar field instability, while $\alpha>0$
decreases it.",2103.03611v1
2021-03-13,Spontaneous Lorentz violation and asymptotic flatness,"The Standard Model Extension (SME) is a generic parametrization for Lorentz
violation and the phenomenological consequences of the minimal gravity sector
of the SME are usually studied using a post-Newtonian expansion that requires
spacetime to be asymptotically flat. However, there is a term in this sector
for which these approximations are unable to make predictions; this is known as
the $t$ puzzle. The present paper studies a model of spontaneous Lorentz
violation in the minimal gravity sector of the SME in a static and spherically
symmetric situation, when no additional matter fields are present. It is shown
that, under the above mentioned assumptions, $t$ is the only term in the
minimal gravity sector for which no asymptotically flat solutions exist. This
stems from the fact that the $t$ term fixes the asymptotic behavior of all the
pieces of the curvature tensor.",2103.07611v2
2021-03-15,Higher-derivative Lorentz-breaking dispersion relations: a thermal description,"This paper is devoted to study the thermal aspects of a photon gas within the
context of Planck-scale-modified dispersion relations. We study the spectrum of
radiation and the correction to the \textit{Stefan$-$Boltzmann} law in
different cases when the Lorentz symmetry is no longer preserved. Explicitly,
we examine two models within the context of CPT$-$even and CPT$-$odd sectors
respectively. To do so, three distinct scenarios of the Universe are
considered: the Cosmic Microwave Background (CMB), the electroweak epoch, and
the inflationary era. Moreover, the equations of state in these cases turn out
to display a dependence on Lorentz-breaking parameters. Finally, we also
provide for both theories the analyses of the Helmholtz free energy, the mean
energy, the entropy and the heat capacity.",2103.08738v3
2021-03-26,1-loop matching of a thermal Lorentz force,"Studying the diffusion and kinetic equilibration of heavy quarks within a hot
QCD medium profits from the knowledge of a coloured Lorentz force that acts on
them. Starting from the spatial components of the vector current, and carrying
out two matching computations, one for the heavy quark mass scale ($M$) and
another for thermal scales ($\sqrt{MT}$, $T$), we determine 1-loop matching
coefficients for the electric and magnetic parts of a Lorentz force. The
magnetic part has a non-zero anomalous dimension, which agrees with that
extracted from two other considerations, one thermal and the other in vacuum.
The matching coefficient could enable a lattice study of a colour-magnetic
2-point correlator.",2103.14270v2
2021-03-30,Non-planar universal anomalous dimension of twist-two operators with general Lorentz spin at four loops in N=4 SYM theory,"We compute the non-planar contribution to the universal anomalous dimension
of twist-two operators in N=4 supersymmetric Yang-Mills theory at four loops
through Lorentz spin eighteen. Exploiting the results of this and our previous
calculations along with recent analytic results for the cusp anomalous
dimension and some expected analytic properties, we reconstruct a general
expression valid for arbitrary Lorentz spin. We study various properties of
this general result, such as its large-spin limit, its small-x limit, and
others. In particular, we present a prediction for the non-planar contribution
to the anomalous dimension of the single-magnon operator in the beta-deformed
version of the theory.",2103.16420v1
2021-04-13,Induced Surface and Curvature Tensions Equation of State of Hadrons with Relativistic Excluded Volumes and its Relation to Morphological Thermodynamics,"An analytical formula that accurately accounts for the Lorentz contraction of
the excluded volume of two relativistic hadrons with hard-core repulsion is
worked out. Using the obtained expression we heuristically derive the equation
of state of Boltzmann particles with relativistic excluded volumes in terms of
system pressure and its surface and curvature tension coefficients. The
behavior of effective excluded volumes of lightest baryons and mesons is
studied at very high temperatures (particle number densities) and for very
large values of degeneracy factors. Several parameterizations of the obtained
equation of state demonstrate a universal asymptotics of the effective excluded
volume at high particle number densities. It is peculiar, that the found
maximal packing fraction $\eta \simeq 0.75$ of Lorentz contracted particles is
very close to the dense packing limit of classical hard spheres of same radius
$\eta_{exc} \approx 0.74$. We show that the developed equation of state is the
grand canonical formulation of the morphological thermodynamics approach
applied to Lorentz contracted rigid spheres.",2104.06528v1
2021-04-28,Another Proof of Born's Rule on Arbitrary Cauchy Surfaces,"In 2017, Lienert and Tumulka proved Born's rule on arbitrary Cauchy surfaces
in Minkowski space-time assuming Born's rule and a corresponding collapse rule
on horizontal surfaces relative to a fixed Lorentz frame, as well as a given
unitary time evolution between any two Cauchy surfaces, satisfying that there
is no interaction faster than light and no propagation faster than light. Here,
we prove Born's rule on arbitrary Cauchy surfaces from a different, but equally
reasonable, set of assumptions. The conclusion is that if detectors are placed
along any Cauchy surface $\Sigma$, then the observed particle configuration on
$\Sigma$ is a random variable with distribution density $|\Psi_\Sigma|^2$,
suitably understood. The main different assumption is that the Born and
collapse rules hold on any spacelike hyperplane, i.e., at any time coordinate
in any Lorentz frame. Heuristically, this follows if the dynamics of the
detectors is Lorentz invariant.",2104.13861v2
2021-05-18,Issues of Lorentz-invariance in f(T) gravity and calculations for spherically symmetric solutions,"The f(T) gravity is nowadays being widely used for cosmological model
building, as well as for constructing spherically symmetric solutions. In its
classical pure tetrad formulation it violates the local Lorentz symmetry in the
space of tetrads. By using an appropriate spin connection it can be brought to
a formally Lorentz invariant shape. However, despite some mathematical elegance
obtained and new options of looking for non-standard couplings to matter
probably made possible, it is fully equivalent in itself to the initial
formulation. It seems that this fact, that the covariantisation does not in
principle change anything, is not understood well by the community. Therefore
we give a pedagogical introduction to these topics. And, on top of that, we
show that obtaining the explicit equations for spherically symmetric solutions
in f(T) gravity is not very difficult computationally and can be easily done
even without any computer at hand.",2105.08586v3
2021-05-19,Isoparametric hypersurfaces induced by navigation in Lorentz Finsler geometry,"Using a navigation process with the datum $(F,V)$, in which $F$ is a Finsler
metric and the smooth tangent vector field $V$ satisfies $F(-V(x))>1$
everywhere, a Lorentz Finsler metric $\tilde{F}$ can be induced. Isoparametric
functions and isoparametric hypersurfaces with or without involving a smooth
measure can be defined for $\tilde{F}$. When the vector field $V$ in the
navigation datum is homothetic, we prove the local correspondences between
isoparametric functions and isoparametric hypersurfaces before and after this
navigation process. Using these correspondences, we provide some examples of
isoparametric functions and isoparametric hypersurfaces on a Funk space of
Lorentz Randers type.",2105.08900v3
2021-05-26,Thermodynamic uncertainty relation in the overdamped limit with a magnetic Lorentz force,"In nonequilibrium systems, the relative fluctuation of a current has a
universal trade-off relation with the entropy production, called the
thermodynamic uncertainty relation (TUR). For systems with broken time reversal
symmetry, its violation has been reported in specific models or in the linear
response regime. Here, we derive a modified version of the TUR analytically in
the overdamped limit for general Langevin dynamics with a magnetic Lorentz
force causing time reversal broken. Remarkably, this modified version is simply
given by the conventional TUR scaled by the ratio of the reduced effective
temperature of the overdamped motion to the reservoir temperature, permitting a
violation of the conventional TUR. Without the Lorentz force, this ratio
becomes unity and the conventional TUR is restored. We verify our results both
analytically and numerically in a specific solvable system.",2105.12421v1
2021-05-31,Fully Hyperbolic Neural Networks,"Hyperbolic neural networks have shown great potential for modeling complex
data. However, existing hyperbolic networks are not completely hyperbolic, as
they encode features in a hyperbolic space yet formalize most of their
operations in the tangent space (a Euclidean subspace) at the origin of the
hyperbolic space. This hybrid method greatly limits the modeling ability of
networks. In this paper, we propose a fully hyperbolic framework to build
hyperbolic networks based on the Lorentz model by adapting the Lorentz
transformations (including boost and rotation) to formalize essential
operations of neural networks. Moreover, we also prove that linear
transformation in tangent spaces used by existing hyperbolic networks is a
relaxation of the Lorentz rotation and does not include the boost, implicitly
limiting the capabilities of existing hyperbolic networks. The experimental
results on four NLP tasks show that our method has better performance for
building both shallow and deep networks. Our code will be released to
facilitate follow-up research.",2105.14686v3
2021-06-02,Photon decay in UHE air showers: stringent bound on Lorentz violation,"In extensive air showers induced by ultra-high-energy (UHE) cosmic rays,
secondary photons are expected to be produced at energies far above those
accessible by other means. It has been shown that the decay of such photons, as
possible in certain theories allowing Lorentz violation, can lead to
significant changes of the shower development. Based on observations of the
average depth of the shower maximum $\left<X_\text{max}\right>$, a stringent
bound on Lorentz violation has been placed in a previous work. Here we include
the shower-to-shower fluctuations $\sigma(X_\text{max})$ as an additional
observable. The combined comparison of $\left<X_\text{max}\right>$ and
$\sigma(X_\text{max})$ to shower observations allows a much stricter test of
the possible decay of UHE photons, improving the previous bound by a factor of
50.",2106.01012v2
2021-06-24,On estimates of the order of approximation of functions of several variables in the anisotropic Lorentz-Karamata space,"In this paper we consider anisotropic Lorentz-Karamata space $2\pi$ of
periodic functions of $m$ variables and Nikol'skii--Besov's class . In this
paper, we establish order-sharp estimates of the best approximation by
trigonometric polynomials with harmonic numbers from the step hyperbolic cross
of functions from the Nikol'skii - Besov class in the norm of the anisotropic
Lorentz-Karamata space.",2106.12761v2
2021-06-30,Radiation reaction and the acceleration-dependent mass increase of a charged sphere undergoing uniform acceleration,"Photon emission from a uniformly accelerated charge is among the most
mysterious physical phenomena. Theories based on the Lorentz-Abraham-Dirac
equation mostly conclude that a uniformly accelerated point charge cannot feel
radiation reaction. Such a conclusion suggests that the origin of the photon
energy is unclear. In this paper, we determine the self-force of a uniformly
accelerated charged sphere using the Lorentz force equation, with an assumption
that the sphere is Lorentz-contracted during the acceleration. For large
acceleration, the calculated self-force converges to the radiation reaction
(given by the Larmor formula) via a new factor $\gamma_{a}$, which describes an
acceleration-dependent increase in the effective mass. This increased mass
makes it harder to accelerate the particle (compared to a point-charge), which
means more energy should be provided to the particle in order to get the
expected acceleration. This extra energy can be interpreted as the origin of
the photon energy.",2107.00043v1
2021-07-10,"Lorentz-symmetry violation in the electroweak sector: scattering processes in future $e^+ \, e^-$ colliders","We study CPT-odd non-minimal Lorentz-symmetry violating couplings in the
electroweak sector modifying the interactions between leptons, gauge mediators
and the Higgs boson. The tree-level (differential) cross sections for three
important electroweak processes are discussed: $e^+ \, e^- \rightarrow Z \, H$,
$e^+ \, e^- \rightarrow Z \, Z$ and $\gamma \, \gamma \rightarrow W^+ \, W^-$.
By considering next-generation $e^+ \, e^-$ colliders reaching center-of-mass
energies at the TeV scale and the estimated improved precision for the
measurements of the respective cross sections, we are able to project upper
bounds on the purely time-like background 4-vector as strict as $\lesssim
10^{-5} \, \mbox{GeV}^{-1}$, in agreement with previous work on similar
Lorentz-violating couplings.",2107.04927v2
2021-07-21,Pinning and gyration dynamics of magnetic vortices revealed by correlative Lorentz and bright-field imaging,"Topological magnetic textures are of great interest in various scientific and
technological fields. To allow for precise control of nanoscale magnetism, it
is of great importance to understand the role of intrinsic defects in the host
material. Here, we use conventional and time-resolved Lorentz microscopy to
study the effect of grain size in polycrystalline permalloy films on the
pinning and gyration orbits of vortex cores inside magnetic nanoislands. To
assess static pinning, we use in-plane magnetic fields to shift the core across
the island while recording its position. This enables us to produce highly
accurate two-dimensional maps of pinning sites. Based on this technique, we can
generate a quantitative map of the pinning potential for the core, which we
identify as being governed by grain boundaries. Furthermore, we investigate the
effects of pinning on the dynamic behavior of the vortex core using
stroboscopic Lorentz microscopy, harnessing a new photoemission source that
accelerates image acquisition by about two orders of magnitude. We find
characteristic changes to the vortex gyration in the form of increased
dissipation and enhanced bistability in samples with larger grains.",2107.10208v1
2021-08-02,The implications of gamma-ray photons from LHAASO on Lorentz symmetry,"The Large High Altitude Air Shower Observatory (LHAASO) has reported the
measurement of photons with high energy up to 1.42 PeV from twelve gamma-ray
sources. We are concerned with the implications of LHAASO data on the fate of
Lorenz symmetry at such high energy level, thus we consider the interaction of
the gamma ray with those photons in cosmic microwave background (CMB), and
compute the optical depth, the mean free path as well as the survival
probability for photons from all these gamma-ray sources. Employing the
threshold value predicted by the standard special relativity, it is found that
the lowest survival probability for observed gamma ray photons is about 0.60,
which is a fairly high value and implies that abundant photons with energy
above the threshold value may reach the Earth without Lorentz symmetry
violation. We conclude that it is still far to argue that the Lorentz symmetry
would be violated due to the present observations from LHAASO.",2108.00869v2
2021-08-16,From GR to STG -- Inheritance and development of Einstein's heritages,"A review of General Relativity, Teleparallel Gravity, and Symmetric
Teleparallel gravity is given in this paper. By comparing these theories some
conclusions are obtained. It is argued that the essence of gravity is the
translation connection. The gauge group associated with gravity is merely the
translation group. Lorentz group is relevant with only inertial effects and has
nothing to do with gravity. The Lorentz connection represents a inertial force
rather than a gauge potential, which leads to the equivalent principle. Neither
curvature nor torsion belongs to spacetime but certain transformation group and
their connections. The statement ""gravity is equivalent to curved spacetime"" is
a misunderstanding, not Einstein's real intention. Not curvature but torsion
i.e. the anholonomy of the tetrad represents gravity. Einstein's great genius
is choosing metric as the fundamental variable to describe gravity. Some
conceptual issues, for example, general covariance, Lorentz covariance,
reference system dependence, gravitational energy-momentum are discussed.",2108.06865v1
2021-09-22,"Design, Fabrication, Characterization and Reliability Study of CMOS-MEMS Lorentz-Force Magnetometers","This article presents several design techniques to fabricate
micro-electro-mechanical systems (MEMS) using standard complementary
metal-oxide semiconductor (CMOS) processes. They were applied to fabricate high
yield CMOS-MEMS shielded Lorentz-force magnetometers (LFM). The multilayered
metals and oxides of the back-end-of-line (BEOL), normally used for electronic
routing, comprise the structural part of the MEMS. The most important
fabrication challenges, modeling approaches and design solutions are discussed.
Equations that predict the Q factor, sensitivity, Brownian noise and resonant
frequency as a function of temperature, gas pressure and design parameters are
presented and validated in characterization tests. A number of the fabricated
magnetometers were packaged into Quad Flat No-leads (QFN) packages. We show
this process can achieve yields above 95 % when the proper design techniques
are adopted. Despite CMOS not being a process for MEMS manufacturing, estimated
performance (sensitivity and noise level) is similar or superior to current
commercial magnetometers and others built with MEMS processes. Additionally,
typical offsets present in Lorentz-force magnetometers were prevented with a
shielding electrode, whose efficiency is quantified. Finally, several
reliability test results are presented, which demonstrate the robustness
against high temperatures, magnetic fields and acceleration shocks.",2109.10980v1
2021-09-28,Lorentz symmetry and high-energy neutrino astronomy,"The search of violation of Lorentz symmetry, or Lorentz violation (LV), is an
active research field. The effects of LV are expected to be very small and
special systems are often used to search it. High-energy astrophysical
neutrinos offer a unique system to search signatures of LV due to the three
factors: high neutrino energy, long propagation distance, and the presence of
quantum mechanical interference. In this brief review, we introduce tests of LV
and summarize existing searches of LV using atmospheric and astrophysical
neutrinos.",2109.13973v2
2021-10-21,Lorentz symmetries and primary constraints in covariant teleparallel gravity,"In this article we explore local Lorentz transformations in theories of
gravity based on the teleparallel formalism. For the teleparallel equivalent of
general relativity (TEGR), the spin connection plays no role in the equations
of motion, and therefore it is possible to simply put it equal to zero with no
change in physical quantities, and then the theory is formulated purely in
terms of the tetrad field which can be freely chosen in any way. In nonlinear
modifications of TEGR, this is a more intricate issue, and vanishing spin
connection is then the Weitzenb\""{o}ck gauge choice which imposes restrictions
on the choice of tetrad. This has led to considering the so-called covariant
formulation of $f(T)$ gravity. We examine the primary constraints arising when
passing to the Hamiltonian framework, and compute their algebra. We show that
the problems of local Lorentz symmetry breaking still appear in this
formulation, even if in a different disguise.",2110.11273v1
2021-10-19,The Lorentz group and the Kronecker product of matrices,"The group $SL(2,\mathbb{C})$ of all complex $2\times 2$ matrices with
determinant one is closely related to the group
$\boldsymbol{\mathcal{L}}_{+}^\uparrow$ of real $4\times 4$ matrices
representing the restricted Lorentz transformations. This relation, sometimes
called the spinor map, is of fundamental importance in relativistic quantum
mechanics and has applications also in general relativity. In this paper we
show how the spinor map may be expressed in terms of pure matrix algebra by
including the Kronecker product between matrices in the formalism. The
so-obtained formula for the spinor map may be manipulated by matrix algebra and
used in the study of Lorentz transformations.",2110.15118v2
2021-11-04,Multiple scattering model of the quantum random Lorentz gas,"A multiple scattering model of a quantum particle interacting with a random
Lorentz gas of fixed point scatterers is established in an Euclidean space of
arbitrary dimension. At the core of the model, the scattering amplitude for the
point scatterers is derived in detail, and expressed in terms of the scattering
length. The fundamental properties of the model, such as the cross section and
the scattering matrix, are calculated. In addition, the model is shown to
verify the optical theorem and thus probability conservation. Finally, the
differential and total cross sections are numerically computed in two
situations whether the Lorentz gas is smaller or larger than the mean free
path. A distinct Airy diffraction peak is obtained for a large enough number of
scatterers. This observation is related to the extinction paradox.",2111.03136v4
2021-11-25,Bianchi type I cosmology with a Kalb-Ramond background field,"An effect of the Lorentz symmetry breaking is pointed out in the cosmological
context. Using a Bianchi I geometry coupled to the Kalb-Ramond field, a
consequence of the Lorentz symmetry violation is indicated by a different rate
of expansion in a given spatial direction. This article focuses on the coupling
constant $\xi_1$, which generates, from the Kalb-Ramond field, all three
coefficients that give rise to the Lorentz violation in the gravity sector of
the minimal Standard Model Extension. The coupling constant $\xi_1$ increases
the rate of expansion of the universe in a given direction during a dark energy
era. As a consequence, a range of validity of that coupling constant is also
obtained.",2111.13165v3
2021-11-30,Quantum power: a Lorentz invariant approach to Hawking radiation,"Particle radiation from black holes has an observed emission power depending
on the surface gravity $\kappa = c^4/(4GM)$ as \begin{equation}\nonumber
P_{\textrm{black hole}} \sim \frac{\hbar \kappa^2}{6\pi c^2} = \frac{\hbar
c^6}{96\pi G^2 M^2}\,,\end{equation} while both the radiation from accelerating
particles and moving mirrors (accelerating boundaries) obey similar
relativistic Larmor powers, \begin{equation}\nonumber P_{\textrm{electron}}=
\frac{q^2\alpha^2}{6\pi \epsilon_0 c^3}\,, \quad P_{\textrm{mirror}}
=\frac{\hbar \alpha^2}{6\pi c^2}\,, \end{equation} where $\alpha$ is the
Lorentz invariant proper acceleration. This equivalence between the Lorentz
invariant powers suggests a close relation that could be used to understand
black hole radiation. We show that an accelerating mirror with a prolonged
metastable acceleration plateau can provide a unitary, thermal,
energy-conserved analog model for black hole decay.",2111.15148v1
2021-12-04,Spatial Curvature and Large Scale Lorentz Violation,"The tension between the Hubble constant obtained from the local measurements
and from cosmic microwave background (CMB) measurements motivated us to
consider the cosmological model beyond $\Lambda$CDM one. We investigate the
cosmology in the large scale Lorentz violation model with non-vanishing spatial
curvature. The degeneracy among spatial curvature, cosmological constant and
cosmological contortion distribution makes the model viable in describing the
known observation date. We get some constraints on the spatial curvature by the
comparison of the relation between measured distance modulus and red-shift with
the predicted one, the evolution of matter density over time and the evolution
of effective cosmological constant. The performance of large scale Lorentz
violation model with non-vanishing spatial curvature under these constrains is
discussed.",2112.02364v1
2021-12-08,Precise design of VO2 thin films for smart windows by employing thickness dependent refractive index,"Vanadium dioxide (VO2) is an adjustable refractive index material and has
capability of behaving as semiconductor or conductor depending on its
temperature. Such condition makes it as a material which can be employed in
fabricating thermochromic smart windows. The transmission characteristics of
these type of windows strongly depend on the thickness of the film. Therefore,
some calculations are required to optimize the VO2 thickness. Unfortunately,
refractive index of VO2 thin film is thickness dependent, therefore, in
calculating the transmission of light spectrum from VO2 thin films, a unique
refractive index cannot be utilized. In the present paper using three
theoretical models (Lorentz-Drude oscillator, Lorentz oscillator, and
Tauc-Lorentz) and employing experimental results from previous reports, we
provide a collection of thickness dependent refractive index of VO2 films. More
precise transmission can be achieved by using this set of refractive index data
in the calculations which agree with those of experiments. These results also
fairly make us capable to determine optimized film thickness for any desired
transmission performance. This method is useful for design of VO2 based
thermochromic smart windows.",2112.04582v1
2022-01-06,Anisotropic Special Relativity,"Anisotropic Special Relativity (ASR) is the relativistic theory of nature
with a preferred direction in space-time. By relaxing the full-isotropy
constraint on space-time to the preference of one direction, we get a
perturbative modification of the Minkowski metric as
$\mathscr{g}_{\mu\nu}=\eta_{\mu\nu}-b\epsilon_{\mu\nu}$ leading to an extension
to the geometrical objects such as line element. The symmetry group of ASR is
obtained to have six generators satisfying the full Lorentz group algebra.
However, the generators are deformed using the perturbation parameter $b$. So,
ASR retains the same representations of Special Relativity (SR) but allows for
Lorentz-invariant violation at the same time. A procedure to make an
anisotropic quantum field theory is provided wherein the Lorentz-invariant
Lagrangians are replaced with their ASR version in which the inner product of
any pair of covariant/contravariant indices is mediated by the anisotropic
metric $\mathscr{g}_{\mu\nu}$.",2201.02201v2
2022-01-27,Weighted Lorentz invariant measures as quantum field theory regulators,"In this work we develop a re-formulation of quantum field theory through the
more general weighted Lorentz invariant measures that the definition of quantum
fields allows; this approach provides finite answers for the long-live problems
of the traditional formulations of quantum field theories, namely, smooth
distributions for the field commutators that are finite a short distances,
finite vacuum expectation values for the energy (without invoking normal
ordering of operators), and finite fluctuations for the field operators. Our
construction is based on a critical point of view on conventional quantum field
theory statements, instead of invoking string theory inspired frameworks, since
they are not necessary. We shall show that the conventional scheme for
constructing quantum field theories has the necessary ingredients for obtaining
generalized versions that, respecting the Lorentz symmetry, allows us to cure
some of the divergences that plague the different formulations, particularly
the ultra-violet divergences; additionally the present scheme will allows us to
construct an infinite family of noncommutative field theories that are compared
with other formulations. At the end, we discuss the impact of our formulation
on particle physics numerology and on the cosmological constant problem",2201.11588v1
2022-02-02,Testing Lorentz Invariance with Neutrinos,"The search for a theory that unifies general relativity and quantum theory
has focused attention on models of physics at the Planck scale. One possible
consequence of models such as string theory may be that Lorentz invariance is
not an exact symmetry of nature. We discuss here some possible experimental and
observational tests of Lorentz invariance involving neutrino physics and
astrophysics.",2202.01183v4
2022-02-09,Aspects of the gauge boson-gaugino mixing in a supersymmetric scenario with Lorentz-symmetry violation,"We write down an $\mathcal{N}=1$ supersymmetric extension for non-Abelian
gauge theories in (1+3) dimensions with a Lorentz- and CPT-violating term of
the Carroll-Field-Jackiw type. By including effects of the background
(supersymmetric) fermion bilinears that accompany Lorentz-symmetry violation in
a Carroll-Field-Jackiw scenario, we investigate both the gauge boson and
gaugino dispersion relations in order to compute their respective masses in
terms of the background structures. Such results open up a potential path
towards a possible mechanism for gaugino-gauge boson conversion, an analogue of
the Primakoff effect, induced here not by an external magnetic field, but
instead by the (Majorana) fermionic sector of the supersymmetry multiplet in
the backstage of the Lorentz-symmetry violation.",2202.04214v2
2022-02-10,On the symmetries of electrodynamic interactions,"The development of relational electromagnetism after Gauss appears to stop
around 1870. Maxwell recognised relational electromagnetism as mathematically
equivalent to his own formulae and called for an explanation of why so
different conceptions have such a large part in common. We reconstruct
relational electromagnetism guided by the No Arbitrariness Principle. Lorenz'
idea of electromagnetic waves, together with the ""least action principle""
proposed by Lorentz are enough to derive Maxwell's equations, the continuity
equation and the Lorentz' force. We show that there must be two more symmetries
in electromagnetism: a descriptive one expressing source/detector relations,
and another relating perceptions of the same source by detectors moving with
different (constant) relative velocities. The Poincar{\'e} group relates
perceived fields by different receivers and Lorentz boosts elate
source/detector perceptions. We answer Maxwell's philosophical question showing
how similar theories can be abduced using different inferred entities. Each
form of abduction implies an interpretation and a facilitation of the
theoretical construction.",2202.06731v4
2022-02-21,Spectral Lag Transition of 32 Fermi Gamma-ray Bursts and their Application on Constraining Lorentz Invariance Violation,"The positive-to-negative transition of spectral lag is an uncommon feature
reported in a small number of GRBs. An application of such a feature has been
made to constrain the critical quantum gravity energy ($E_{\rm QG}$) of the
light photons under the hypothesis that the Lorentz invariance might be
violated. Motivated by previous case studies, this paper systematically
examined the up-to-date Fermi/GBM GRB sample for the lag transition feature to
establish a comprehensive physical limit on the Lorentz Invariance Violation
(LIV). This search resulted in 32 GRBs with redshift available, which exhibit
the lag-transition phenomenon. We first fit each of the lag-E relations of the
32 GRBs with an empirical smoothly broken power law function, and found that
the lag transition occurs typically at about 400 keV. We then implemented the
LIV effect into the fit, which enabled us to constrain the lower limit of the
linear and quadratic values of $E_{\rm QG}$, which are typically distributed at
$1.5\times 10^{14}$ GeV and $8\times 10^{5}$ GeV, respectively.",2202.09999v1
2022-02-25,Lorentz invariance violation (LIV) in some basic phenomena in quantum physics,"Lorentz symmetry is one of the cornerstone of both general relativity and the
standard model of particle physics. We study the violation of Lorentz symmetry
in some basic phenomena in atomic physics. Using the Green's function, and the
source 4-current, the differential equation of 4-vector of electromagnetic
potential is solved and the modified coulomb potential is obtained by some
researchers. Using modified Coulomb potential, we find the corrections due to
LIV on the spectrum of Hydrogen and Helium atoms. We also investigate the
consequences of LIV on Stark, Zeeman and Spin orbit effects and obtain some
upper bounds for the LIV coefficients.",2202.12688v1
2022-05-12,Relativistic QFT from a Bohmian perspective: A proof of concept,"Since Bohmian mechanics is explicitly nonlocal, it is widely believed that it
is very hard, if not impossible, to make Bohmian mechanics compatible with
relativistic quantum field theory (QFT). I explain, in simple terms, that it is
not hard at all to construct a Bohmian theory that lacks Lorentz covariance,
but makes the same measurable predictions as relativistic QFT. All one has to
do is to construct a Bohmian theory that makes the same measurable predictions
as QFT in one Lorentz frame, because then standard relativistic QFT itself
guarantees that those predictions are Lorentz invariant. I first explain this
in general terms, then I describe a simple Bohmian model that makes the same
measurable predictions as the Standard Model of elementary particles, after
which I give some hints towards a more fundamental theory beyond Standard
Model. Finally, I present a short story telling how my views of fundamental
physics in general, and of Bohmian mechanics in particular, evolved over time.",2205.05986v2
2022-05-28,Meson scattering in a Lorentz-violating scalar QED at finite temperature,"This paper investigates how the nonzero temperature affects the differential
cross-section for mesons scattering in a Lorentz-violating extension of the
scalar electrodynamics. We initially discuss some features of the model and
extract the zero temperature Feynman rules. Temperature effects are introduced
using the Thermo Field Dynamics (TFD) formalism. It is shown that the
corrections induced on the meson scattering are very large in the
high-temperature regime. Furthermore, our results also suggest that temperature
effects may contribute to new constraints on the Lorentz-violating parameters.",2205.14513v3
2022-06-15,Spectral properties of the inhomogeneous Drude-Lorentz model with dissipation,"We establish spectral enclosures and spectral approximation results for the
inhomogeneous lossy Drude-Lorentz system with purely imaginary poles, in a
possibly unbounded Lipschitz domain of $\mathbb{R}^3$. Under the assumption
that the coefficients $\theta_e$, $\theta_m$ of the material are asymptotically
constant at infinity, we prove that: 1) the essential spectrum can be
decomposed as the union of the spectrum of a bounded operator pencil in the
form $- \operatorname{div} p(\omega) \nabla$ and of a second order
$\operatorname{curl} \operatorname{curl}_0 - V_{e,\infty}(\omega)$ pencil with
constant coefficients; 2) spectral pollution due to domain truncation can lie
only in the essential numerical range of a $\operatorname{curl}
\operatorname{curl}_0 - f(\omega)$ pencil. As an application, we consider a
conducting metamaterial at the interface with the vacuum; we prove that the
complex eigenvalues with non-trivial real part lie outside the set of spectral
pollution. We believe this is the first result of enclosure of spectral
pollution for the Drude-Lorentz model without assumptions of compactness on the
resolvent of the underlying Maxwell operator.",2206.07644v2
2022-06-25,Lorentz violating inflation and the Swampland,"The swampland conjectures from String theory have had very interesting
implications for cosmology and particularly for Inflation. It has been shown
that the single field inflationary models in a GR based cosmology are in
unavoidable tensions with these conjectures and so it becomes interesting to
see whether there is a way to overcome the issues of the swampland and single
field inflation in an essentially GR based cosmology. We show that this can be
the case if one considers a certain type of Lorentz violating inflationary
scenario. We work out the requirements for these inflationary models to be
swampland consistent and then show how this scenario allows some popular
inflationary potentials to be swampland consistent as well.",2206.12619v1
2022-07-09,Lorentz-violating electrodynamics in continuous matter,"We review the propagation of electromagnetic waves in continuous matter in
the presence of Lorentz-violating terms. First, we briefly discuss classical
electrodynamics with regard to optical properties of a dielectric medium
exhibiting the Chiral Magnetic Effect (CME). Such a medium can be modeled by
Maxwell-Carroll-Field-Jackiw (MCFJ) theory. Second, we describe the impact of
CPT-odd terms of mass dimensions three and five, respectively, on
electromagnetic propagation in continuous matter. Birefringence and absorption
are analyzed in the scenarios investigated. Our findings provide new insights
into the interplay between classical field theory and optical effects in
matter.",2207.04311v2
2022-07-14,Testing the scalar sector of the Standard-Model Extension with neutron gravity experiments,"In the present study we analyse, within the scalar sector of the
Standard-Model Extension (SME) framework, the influence of a spontaneous
Lorentz symmetry breaking on gravitational quantum states of ultracold
neutrons. The model is framed according to the laboratory conditions of the
recent high-sensitivity GRANIT and $q$Bounce experiments. The high-precision
data achieved in such experiments allow us to set bounds on the symmetry
breaking parameters of the model. The effective Hamiltonian governing the
neutron's motion along the axis of free fall is derived explicitly. It
describes a particle in a gravitational field with an effective gravitational
constant controlled non-trivially by the Lorentz-violating parameters. In
particular, using the exact wave functions and the energy spectrum, we evaluate
both the heights associated with the quantum states and the transition
frequencies between neighborhoring quantum states. By comparing our theoretical
results with those reported in the GRANIT and the $q$Bounce experiments, upper
bounds on the Lorentz-violating parameters are determined. We also consider for
the first time the gravity-induced interference pattern in a COW-type
experiment to test Lorenz-invariance. In this case, an upper bound for the
parameters is established as well.",2207.06600v1
2022-07-18,Gravitational Tunneling in Lorentz Violating Gravity,"Black holes in Lorentz violating gravity, such as Einstein--Aether or
Horava--Lifshitz Gravity, are drastically different from their general
relativistic siblings. Although they allow for superluminal motion in their
vicinity, they still exhibit an absolute causal boundary in the form of a
universal horizon. By working in the tunneling picture for a gravitating scalar
field, we show that universal horizons emit Hawking radiation in a manner akin
to standard results in General Relativity, with a temperature controlled by the
high-energy behavior of the dispersion relation of the gravitating field, and
in agreement with alternative derivations in the literature. Our results
substantiate the link between the universal horizon and thermodynamics in
Lorentz violating theories.",2207.08848v3
2022-07-29,Maxwell's equations and Lorentz force in doubly special relativity,"On the basis of all commutation relations of the k-deformed phase space
incorporating the k-Minkowski space-time, we have derived in this paper an
extended first approximation of both Maxwell's equations and Lorentz force in
doubly (or deformed) special relativity (DSR). For this purpose, we have used
our approach of the special relativistic version of Feynman's proof by which we
have established the explicit formulations of electric and magnetic fields. As
in Fock's nonlinear relativity (FNLR), the laws of electrodynamics depend on
the particle mass which therefore constitutes a common point between the two
extended forms of special relativity. As one consequence, the corresponding
equation of motion contains two different types of contributions. In addition
to the usual type, another one emerges as a consequence of the coexistence of
mass and charge which are coupled with the k-deformation and electromagnetic
field. This new effect completely induced by the k-deformed phase space is
interpreted as the gravitational-type Lorentz force. Unlike FNLR, the
corrective terms all depend on the electromagnetic field in DSR.",2207.14531v1
2022-07-29,Exact form of the generalized Lorentz force in Fock's nonlinear relativity,"This work completes a serie of two papers devoted to the extension of the
fundamental laws of electrodynamics in the context of Fock's nonlinear
relativity (FNLR). Indeed, after having established in the previous study the
exact generalizations of both Maxwell's equations and Dirac magnetic monopole,
we present here the remaining exact Lorentz force. As in k-Minkowski spacetime,
two different nature contributions appear in the corresponding equation of
motion where the new effect is interpreted as the gravitational-type Lorentz
force. This common point separately induced by the radius of the universe in
our case or Planck energy in other works, reinforces once more the analogy
between electromagnetism and gravity in two different scientific approaches. As
a relative difference, it is very important to highlight that more homogeneity
characterizes our results where each effect is exclusively generated by mass or
charge but not both at the same time. Even more, the new effect emerges as the
result of the triple effect of R-deformation, mass and the square of velocities
but completely independent of electromagnetic field.",2207.14546v1
2022-08-16,Holographic Lorentz and Carroll Frames,"Relaxing the Bondi gauge, the solution space of three-dimensional gravity in
the metric formulation has been shown to contain an additional free function
that promotes the boundary metric to a Lorentz or Carroll frame, in
asymptotically AdS or flat spacetimes. We pursue this analysis and show that
the solution space also admits a finite symplectic structure, obtained taking
advantage of the built-in ambiguities. The smoothness of the flat limit of the
AdS symplectic structure selects a prescription in which the holographic
anomaly appears in the boundary Lorentz symmetry, that rotates the frame. This
anomaly turns out to be cohomologically equivalent to the standard holographic
Weyl anomaly and survives in the flat limit, thus predicting the existence of
quantum anomalies in conformal Carrollian field theories. We also revisit these
results in the Chern--Simons formulation, where the prescription for the
symplectic structure admitting a smooth flat limit follows from the variational
principle, and we compute the charge algebra in the boundary conformal gauge.",2208.07575v1
2022-06-26,Covariant Space Time Line Elements in the Friedmann Lemaitre Robertson Walker Geometry,"Most quantum gravity theories quantize space time on the order of Planck
length (lp). Some of these theories, such as loop quantum gravity (LQG),
predict that this discreetness could be manifested through Lorentz invariance
violations (LIV) over travelling particles at astronomical length distances.
However, reports on LIV are controversial, and space discreetness could still
be compatible with Lorentz invariance. Here, it is tested whether space
quantization on the order of Planck length could still be compatible with
Lorentz invariance through the application of a covariant geometric uncertainty
principle (GeUP) as a constraint over geodesics in FRW geometries. Space time
line elements compatible with the uncertainty principle are calculated for a
homogeneous, isotropic expanding Universe represented by the Friedmann Lemaitre
Robertson Walker solution to General Relativity (FLRW or FRW metric). A generic
expression for the quadratic proper space time line element is derived,
proportional to Planck length squared, and dependent on two contributions. The
first is associated to the energy time uncertainty, and the second depends on
the Hubble function. The results are in agreement with space-time quantization
on the expected length orders, according to quantum gravity theories, and
within experimental constraints on putative LIV.",2209.06073v1
2022-09-06,General relativity and background Lorentz transformations solve Supplee's submarine paradox,"A submarine moving at relativistic horizontal velocity sinks in Earth's rest
frame due to length contraction while appearing to float in its own frame.
Using spacetime geometry and the Lorentz transformations, we show that the
resolution lies in how metric components transform between reference frames in
relative motion. This solution frees us from assumptions made in previous
studies on how a Newtonian gravitational force should transform. The method of
background Lorentz transformations is technically simpler than previous
treatments in the framework of general relativity. Moreover, we find a novel
and intuitive understanding of the paradox, and correct an erroneous expression
for the gravitational force obtained by Supplee and used again in the
literature.",2209.07470v3
2022-09-22,Lorentz symmetry violating Lifshitz-type field theories,"We discuss the ultraviolet sector of 3+1 dimensional Lifshitz-type
anisotropic higher derivative scalar, fermion and gauge field theories, with
anisotropy exponent z=3 and with explicit breaking of Lorentz symmetry. By
discarding from the action all momentum dependent vertex operators, which is
essential to avoid phenomenologically unacceptable deformations of the light
cone, we find that renormalizable scalar self-interaction and Yukawa-like
couplings are, in general, asymptotically free. However, the requirement of
cancelling momentum dependent vertex operators is incompatible with gauge
symmetry and, therefore, for this kind of theories, gauge symmetry as well as
Lorentz symmetry are recovered only as emergent properties below some energy
scale M, that must be constrained from experiments. The quantum corrections to
the scalar mass and their impact on the hierarchy problem are also analyzed.",2209.11060v1
2022-09-23,Thermodynamics of a quantum ring modified by Lorentz violation,"In this work, we investigate the consequences of Lorentz-violating terms in
the thermodynamic properties of a 1-dimensional quantum ring. Particularly, we
use the ensemble theory to obtain our results of interest. The thermodynamic
functions as well as the spin currents are calculated as a function of the
temperature. We observe that parameter $\xi$, which triggers the Lorentz
symmetry breaking, plays a major role in low temperature regime. Finally,
depending on the configuration of the system, electrons can rotate in two
different directions: clockwise and counterclockwise.",2209.11744v2
2022-10-17,Scalar Casimir effects in a Lorentz violation scenario induced by the presence of constant vectors,"In this work, we consider a theoretical model that presents violation of the
Lorentz symmetry in the approach of Quantum Field Theory. The theoretical model
adopted consists of a real massive scalar quantum field confined in the region
between two large parallel plates. The Lorentz symmetry violation is introduced
by CPT-even, aether-like approach, considering a direct coupling between the
derivative of the the scalar field with two orthogonal constant vectors. The
main objective of this paper is to analyze the modification on the Casimir
energy and pressure caused by the anisotropy of the space-time as consequence
of these couplings. The confinement of the scalar quantum field between the
plates is implemented by the imposition boundaries conditions on them.",2210.09243v2
2022-10-17,Long time behaviour of the solution of Maxwell's equations in dissipative generalized Lorentz materials (I) A frequency dependent Lyapunov function approach,"It is well-known that electromagnetic dispersive structures such as
metamaterials can be modelled by generalized Drude-Lorentz models. The present
paper is the first of two articles dedicated to dissipative generalized
Drude-Lorentz open structures. We wish to quantify the loss in such media in
terms of the long time decay rate of the electromagnetic energy for the
corresponding Cauchy problem. By using an approach based on frequency dependent
Lyapounov estimates, we show that this decay is polynomial in time. These
results extend to an unbounded structure the ones obtained for bounded media in
[18] via a quite different method based on the notion of cumulated past history
and semi-group theory. A great advantage of the approach developed here is to
be less abstract and directly connected to the physics of the system via energy
balances.",2210.09360v1
2022-10-26,Joint photon-electron Lorentz violation parameter plane from LHAASO data,"The Large High Altitude Air Shower Observatory~(LHAASO) is one of the most
sensitive gamma-ray detector arrays, whose ultrahigh-energy~(UHE) work bands
not only help to study the origin and acceleration mechanism of UHE cosmic
rays, but also provide the opportunity to test fundamental physics concepts
such as Lorentz symmetry. LHAASO directly observes the $1.42~\mathrm{PeV}$
highest-energy photon. By adopting the synchrotion self-Compton model, LHAASO
also suggests that the $1.12~\mathrm{PeV}$ high-energy photon from Crab Nebula
corresponds to a $2.3~\mathrm{PeV}$ high-energy electron. We study the
$1.42~\mathrm{PeV}$ photon decay and the $2.3~\mathrm{PeV}$ electron decay to
perform a joint analysis on photon and electron two-dimensional Lorentz
violation~(LV) parameter plane. Our analysis is systematic and comprehensive,
and we naturally get the strictest constraints from merely considering photon
LV effect in photon decay and electron LV effect in electron decay. Our result
also permits the parameter space for new physics beyond relativity.",2210.14817v3
2022-10-31,The Numerical Stability of Hyperbolic Representation Learning,"Given the exponential growth of the volume of the ball w.r.t. its radius, the
hyperbolic space is capable of embedding trees with arbitrarily small
distortion and hence has received wide attention for representing hierarchical
datasets. However, this exponential growth property comes at a price of
numerical instability such that training hyperbolic learning models will
sometimes lead to catastrophic NaN problems, encountering unrepresentable
values in floating point arithmetic. In this work, we carefully analyze the
limitation of two popular models for the hyperbolic space, namely, the
Poincar\'e ball and the Lorentz model. We first show that, under the 64 bit
arithmetic system, the Poincar\'e ball has a relatively larger capacity than
the Lorentz model for correctly representing points. Then, we theoretically
validate the superiority of the Lorentz model over the Poincar\'e ball from the
perspective of optimization. Given the numerical limitations of both models, we
identify one Euclidean parametrization of the hyperbolic space which can
alleviate these limitations. We further extend this Euclidean parametrization
to hyperbolic hyperplanes and exhibits its ability in improving the performance
of hyperbolic SVM.",2211.00181v3
2022-11-01,Ultra-high energy cosmic neutrinos from gamma-ray bursts,"Based on recent proposal to associate IceCube TeV and PeV neutrino events
with gamma-ray bursts~(GRBs) by considering the Lorentz violation of neutrinos,
we provide a new estimate on the GRB neutrino flux and such result is much
bigger than previous results by the IceCube Collaboration. Among these 24
neutrino ``shower"" events above 60~TeV, 12 events are associated with GRBs.
Such result is comparable with the prediction from GRB fireball models.
Analysis of track events provide consistent result with the shower events to
associate high energy cosmic neutrinos with GRBs under the same Lorentz
violation features of neutrinos. We also make a background estimation and
reveal GRBs as a significant source for the ultra-high energy IceCube neutrino
events. Our work supports the Lorentz violation and $CPT$-violation of
neutrinos, indicating new physics beyond relativity.",2211.00231v2
2022-11-01,PELICAN: Permutation Equivariant and Lorentz Invariant or Covariant Aggregator Network for Particle Physics,"Many current approaches to machine learning in particle physics use generic
architectures that require large numbers of parameters and disregard underlying
physics principles, limiting their applicability as scientific modeling tools.
In this work, we present a machine learning architecture that uses a set of
inputs maximally reduced with respect to the full 6-dimensional Lorentz
symmetry, and is fully permutation-equivariant throughout. We study the
application of this network architecture to the standard task of top quark
tagging and show that the resulting network outperforms all existing
competitors despite much lower model complexity. In addition, we present a
Lorentz-covariant variant of the same network applied to a 4-momentum
regression task.",2211.00454v2
2022-11-06,QNMs of slowly rotating Einstein-Bumblebee Black Hole,"We have studied the quasinormal modes (QNMs) of a slowly rotating black hole
with Lorentz-violating parameter in Einstein-bumblebee gravity. We analyse the
slow rotation approximation of the rotating black hole in the
Einstein-bumblebee gravity, and obtain the master equations for scalar
perturbation, vector perturbation and axial gravitational perturbation,
respectively. Using the matrix method and the continuous fraction method, we
numerically calculate the QNM frequencies. In particular, for scalar field, it
shows that the QNMs up to the second order of rotation parameter have higher
accuracy. The numerical results show that, for both scalar and vector fields,
the Lorentz-violating parameter has a significant effect on the imaginary part
of the QNM frequencies, while having a relatively smaller impact on the real
part of the QNM frequencies. But for axial gravitational perturbation, the
effect of increasing the Lorentz-violating parameter $\ell$ is similar to that
of increasing the rotation parameter $\tilde{a}$.",2211.03156v2
2022-11-21,Vacuum solution within a metric-affine bumblebee gravity,"We consider a metric-affine extension to the gravitational sector of the
Standard-Model Extension for the Lorentz-violating coefficients $u$ and
$s^{\mu\nu}$. The general results, which are applied to a specific model called
metric--affine bumblebee gravity, are obtained. A Schwarzschild-like solution,
incorporating effects of the Lorentz symmetry breaking through coefficient
$X=\xi b^2$, is found. Furthermore, a complete study of the geodesics
trajectories of particles has been accomplished in this background, emphasizing
the departure from general relativity. We also compute the advance of Mercury's
perihelion and the deflection of light within the context of the weak field
approximation, and we verify that there exist two new contributions ascribed to
the Lorentz symmetry breaking. As a phenomenological application, we compare
our theoretical results with observational data in order to estimate the
coefficient $X$.",2211.11821v2
2022-12-14,Lorentz group equivariant autoencoders,"There has been significant work recently in developing machine learning (ML)
models in high energy physics (HEP) for tasks such as classification,
simulation, and anomaly detection. Often these models are adapted from those
designed for datasets in computer vision or natural language processing, which
lack inductive biases suited to HEP data, such as equivariance to its inherent
symmetries. Such biases have been shown to make models more performant and
interpretable, and reduce the amount of training data needed. To that end, we
develop the Lorentz group autoencoder (LGAE), an autoencoder model equivariant
with respect to the proper, orthochronous Lorentz group $\mathrm{SO}^+(3,1)$,
with a latent space living in the representations of the group. We present our
architecture and several experimental results on jets at the LHC and find it
outperforms graph and convolutional neural network baseline models on several
compression, reconstruction, and anomaly detection metrics. We also demonstrate
the advantage of such an equivariant model in analyzing the latent space of the
autoencoder, which can improve the explainability of potential anomalies
discovered by such ML models.",2212.07347v2
2022-12-19,Should Unstable Quantum Field Theories be Lorentz Invariant?,"An unstable field theory is what we obtain when we linearise the equations of
an interacting field theory near an unstable state. Theories of this kind are
adopted to model the onset of spontaneous symmetry breakings, when the fields
are sitting on the top of the Mexican hat, and they start to ''roll down'' to
the bottom. At present, there exists no rigorous proof that unstable quantum
field theories are Lorentz-invariant (in the sense of Wigner's theorem). Here,
we show that they shouldn't be. In fact, unstable theories always have a
limited regime of applicability, and they are valid only for a very short time.
As consequence, there is a preferred simultaneity hyperplane, along which the
unstable theory is everywhere applicable, while a generic observer (whose
four-velocity is not orthogonal to such hyperplane) must use the full
non-linear theory. In summary: the current quantization schemes are ''ok'',
independently from whether they lead to a Lorentz-invariant theory.",2212.09625v1
2022-12-27,The Real Dirac Equation,"Dirac's leaping insight that the normalized anti-commutator of the
{\gamma}^{\mu} matrices must equal the timespace signature {\eta}^{\mu}{\nu}
was decisive for the success of his equation. The {\gamma}^{\mu}-s are the same
in all Lorentz frames and ""describe some new degrees of freedom, belonging to
some internal motion in the electron"". Therefore, the imposed link to
{\eta}^{\mu}{\nu} constitutes a separate postulate of Dirac's theory. I derive
a manifestly covariant first order equation from the direct quantization of the
classical 4-momentum vector using the formalism of Geometric Algebra. All
properties of the Dirac electron & positron follow from the equation -
preconceived 'internal degrees of freedom', ad hoc imposed signature and
matrices unneeded. In the novel scheme, the Dirac operator is frame-free and
manifestly Lorentz invariant. Relative to a Lorentz frame, the classical
spacetime frame vectors e^{\mu} appear instead of the {\gamma}^{\mu} matrices.
Axial frame vectors (without cross product) of the 3D orientation space
defining spin and rotations appear instead of the Pauli matrices; polar frame
vectors of the 3D position space naturally define boosts, etc. Not the least,
the formalism shows a significantly higher computational efficiency compared to
matrices.",2212.13568v3
2023-01-04,Covariant orbital-spin scheme for any spin based on irreducible tensor,"In hadron spectrum physics, the partial wave analysis is a primary method
used to extract properties of hadronic resonances. The covariant orbital-spin
coupling scheme holds unique advantages over other partial wave methods due to
its Lorentz covariant form and determined orbital-spin quantum numbers. This
paper presents a general form of the covariant orbital-spin coupling scheme
based on the irreducible tensor of the homogeneous proper Lorentz group and its
little groups. A systematic procedure for constructing partial wave amplitude
in a Lorentz covariant way is provided, which can be applied to both massive
and massless particles. Specific examples are also included.",2301.01575v3
2023-02-10,The full Lorentz-violating vacuum polarization tensor: low and high energy limits,"We compute the full vacuum polarization tensor in the fermion sector of
Lorentz-violating QED. Even if we assume momentum routing invariance of the
Feynman diagrams, it is not possible to fix all surface terms and find an
unambiguity free vacuum polarization tensor. The high and low energy limits of
this tensor is presented. In the high energy limit, only $c_{\mu\nu}$
coeffcients contribute. In the low energy limit, we fnd that Lorentz-violating
induced terms depend only on $b_{\mu}$, $c_{\mu\nu}$ and $g_{\mu\nu\lambda}$
coeffcients and they are suppressed by powers of $\frac{p^{2}}{m^{2}}$. This
limit allows to obtain implications for condensed matter systems, explicitly,
for the Hall effect in Weyl semimetals.",2302.05236v2
2023-03-01,Thermodynamics and Shadows of GUP-corrected Black Holes with Topological Defects in Bumblebee Gravity,"In this work we investigate a Schwarzschild-type black hole that is corrected
by the Generalized Uncertainty Principle (GUP) and possesses topological
defects within the framework of Bumblebee gravity. Our focus is on the
thermodynamic characteristics of the black hole, such as temperature, entropy
and heat capacity, which vary as functions of the horizon radius, and also on
shadow as an optical feature. Our investigation reveals significant changes in
the thermodynamic behavior of the black hole due to violations of Lorentz
symmetry, GUP corrections, and the presence of monopoles. However, the shadow
of the black hole is unaffected by violations of Lorentz symmetry. In addition,
we provide a limit on the parameters of Lorentz symmetry violation, GUP and
topological defects based on a classical test involving the precession of
planetary orbits and the advancement of perihelion in the solar system.",2303.00297v2
2023-03-08,Lorentz and CPT breaking in gamma-ray burst neutrinos from string theory,"Previous studies on high-energy gamma-ray burst neutrinos from IceCube
suggest a neutrino speed variation at the Lorentz violation~(LV) scale of $\sim
6.4\times 10^{17}$~GeV, with opposite velocity variances between neutrinos and
antineutrinos. Within a space-time foam model, inspired by string theory, we
develop an approach to describe the suggested neutrino/antineutrino propagation
properties with both Lorentz invariance and CPT symmetry breaking. A threshold
analysis on the bremsstrahlung of electron-positron pair~($\nu\rightarrow\nu
ee^{+}$) for the superluminal~(anti)neutrino is performed. We find that, due to
the energy violation caused by the quantum foam, such reaction may be
restricted to occur at sufficient high energies and could even be kinematically
forbidden. Constraints on neutrino LV from vacuum $ee^{+}$ pair emission are
naturally avoided. Future experiments are appealed to test further the CPT
violation of cosmic neutrinos and/or neutrino superluminality.",2303.04765v2
2023-04-11,The Boltzmann-Grad Limit of the Lorentz Gas in a Union of Lattices,"The Lorentz gas describes an ensemble of noninteracting point particles in an
infinite array of spherical scatterers. In the present paper we consider the
case when the scatterer configuration P is a fixed union of (translated)
lattices in R^d, and prove that in the limit of low scatterer density, the
particle dynamics converges to a random flight process. In the special case
when the lattices in P are pairwise incommensurable, this settles a conjecture
from [20]. The proof is carried out by applying a framework developed in recent
work by Marklof and Str\""ombergsson [21], and central parts of our proof are
the construction of an admissible marking of the point set P, and the
verification of the uniform spherical equidistribution condition required in
[21]. Regarding the random flight process obtained in the low density limit of
the Lorentz gas, we prove that it can be reconstructed from the corresponding
limiting flight processes arising from the individual commensurability classes
of lattices in P. We furthermore prove that the free path lengths of the limit
flight process have a distribution with a power law tail, whose exponent
depends on the number of commensurability classes in P.",2304.05458v1
2023-04-16,Quasinormal Modes and Bounding Greybody Factors of GUP-corrected Black Holes in Kalb-Ramond Gravity,"The vacuum expectation value of the non-minimally coupled Kalb-Ramond (KR)
field leads to spontaneous local Lorentz symmetry violation, and static
spherically symmetric solutions exist. In this study, we study the quasinormal
modes (QNMs) of modified black holes in non--minimally coupled KR gravity. We
employ a higher-order Pad\'e averaged WKB method to compute the QNMs for
scalar, electromagnetic, and gravitational perturbations. In order to account
for quantum corrections, we examine the geometric characteristics of the
horizon and QNMs by introducing the generalized uncertainty principle (GUP).
Additionally, we shed light on the impact of the Lorentz violating parameters
on our findings and estimate QNMs for different perturbations. Further, we
estimate bounds on the greybody factors for the modified and GUP-corrected
black holes. Our findings reveal the influence of the Lorentz violating
parameters in the model on the QNM frequencies and their reliance on the GUP
parameters.",2304.07761v2
2023-04-18,Trajectories of astroparticles in pseudo-Finsler spacetime with the most general modified dispersion,"Finsler geometry is a natural and fundamental generalization of Riemann
geometry, and is a tool to research Lorentz invariance violation. We find the
connection between the most general modified dispersion relation and a
pseudo-Finsler structure, and then we calculate the arrival time delay of
astroparticles with different modified dispersion relations in the framework of
Finsler geometry. The result suggests that the time delay is irrelevant with
the exact form of the modified dispersion relation. If the modified term
becomes 0 when $E=p$, there is no arrival time difference, otherwise the time
delays only depend on the Lorentz violation scale and the order at which the
Lorentz invariance breaks.",2304.08676v2
2023-05-09,Asymptotic symmetry algebra of Einstein gravity and Lorentz generators,"The asymptotic symmetry algebra of four-dimensional Einstein gravity in the
asymptotically flat context has been shown recently to be the direct sum of the
Poincar\'e algebra and of an infinite-dimensional abelian algebra (with central
charge) that includes the Bondi-Metzner-Sachs supertranslations. This result,
obtained within the Hamiltonian formalism, yields a supertranslation invariant
definition of the Lorentz generators (angular momentum and boosts). Definitions
of Lorentz generators free from the ``supertranslation ambiguities'' have also
been proposed recently at null infinity. We prove the equivalence of the two
approaches for redefining the charges.",2305.05436v2
2023-06-12,Lorentz-violating extension of scalar QED at finite temperature,"In this work, we calculate the one-loop self-energy corrections to the gauge
field in scalar electrodynamics modified by Lorentz-violating terms within the
framework of the standard model extension (SME). We focus on both $CPT$-even
and $CPT$-odd contributions. The kinetic part of the scalar sector contains a
$CPT$-even symmetric Lorentz-breaking tensor, and the interaction terms include
a vector contracted with the usual covariant derivative in a gauge-invariant
manner. We computed the one-loop radiative corrections using dimensional
regularization for both the $CPT$-even and $CPT$-odd cases. Additionally, we
employed the Matsubara formalism to account for finite temperature effects.",2306.06959v2
2023-06-14,Two-loop renormalization of the CPT-even Lorentz-violating Scalar QED,"Investigating quantum effects arising from high loops in perturbation theory
is crucial for the physical applications of any quantum field theory. This
paper presents a comprehensive analysis of the two-loop renormalization of
CPT-even Lorentz-violating scalar electrodynamics at the first order in the
background vectors. We provide results for the self-energies of the photon and
scalar field, as well as for the three-point function associated with the
scalar-scalar-photon vertex, ensuring a thorough examination of the quantum
effects. The calculations satisfy the ward identities, demonstrating their
consistency. Computational tools were employed to carry out the calculations,
and we provide additional details in the Supplemental Material for interested
readers. Our contribution presents, for the first time, a two-loop calculation
within the framework of the Lorentz-violating Standard Model Extension.",2306.08488v1
2023-06-14,Lorentz-like extension Mixing Higgs and Gauge Fields in a U(1) symmetric model,"A program searching for symmetry structures behind some features of the
standard Model is launched. After addressing known no-go theorems, we construct
a novel symmetry mixing gauge and Higgs fields which is a Lorentz symmetry
extension involving gauge symmetries. We construct a field theory model with
such a local symmetry, which is in turn invariant under local Lorentz
transformations. We address the action of extended symmetries on the geometric
frame, and models with extra dimensions. This features the novelty of diverse
covariant derivatives associated to non--commuting differential operators, and
their associated curvatures. Mass--like terms arise accompanying non--commuting
differential operators. A novel formalism for constructing an invariant
Lagrangian in direct correspondence to obtained casimir operators --embodying a
long sought paradigm-- is developed. It recovers both gauge as well as some
sort of Higgs-like potential. Equations of motion and conserved currents are
found. Some exploration is devoted to possible invariant measures hinting
possible approaches to address anomalies.",2306.08764v2
2023-07-07,Exploration of possible signals beyond special relativity using high-energy astroparticle physics,"To unify the standard model of particle physics and general relativity, we
may require a quantum description of gravity, which will change our notion of
spacetime at very high energies. In this dissertation we explore possible
traces of new physics beyond special relativity, using the propagation of high
energy astroparticles. For this purpose, the two ways of going beyond Lorentz
invariance are presented, a breaking of the Lorentz invariance (Lorentz
invariance violation or LIV or its deformation (doubly special relativity or
DSR), emphasizing their conceptual and phenomenological differences. For the
study of LIV, the work focuses on the prediction of modifications in the
expected neutrino flux on Earth, both from astrophysical and cosmogenic origin
(from the interaction of cosmic rays with the background radiation during their
propagation). For the study of DSR we focus instead on the search for anomalies
in the time of flight of massless particles (time delays) and on the study of
the expected flux of gamma rays on Earth. The results obtained show the
possibility of using astroparticle observations as a window to quantum gravity
phenomenology, at energies attainable at present and/or in the very near
future.",2307.03462v2
2023-07-21,On Numerical Simulations of Intergalactic Electromagnetic Cascades with Lorentz Invariance Violation,"Lorentz invariance violation (LIV) is a proposed phenomenon where Lorentz
symmetry is violated at high energies, potentially affecting particle dynamics
and interactions. We use numerical simulations with the CRPropa framework to
investigate LIV in gamma-ray-induced electromagnetic cascades, specifically
studying how it impacts cascading electrons and photons undergoing pair
production and inverse Compton scattering. Our detailed analysis of the
simulation results, compared with existing theoretical models, reveals that LIV
can significantly alter the behavior of both components of the cascade, photons
and electrons, resulting in specific signatures in measured fluxes that could
be observed in high-energy gamma-ray observations. These insights are crucial
for ongoing searches for LIV and for the development of theoretical models
incorporating LIV effects.",2307.11421v1
2023-07-26,One-loop radiative corrections in bumblebee-Stueckelberg model,"This work aims to study the radiative corrections in a vector model with
spontaneous Lorentz symmetry violation, known in the literature as the
bumblebee model. We consider such a model with self-interaction quadratic
smooth potential responsible for spontaneous Lorentz symmetry breaking. The
spectrum of this model displays a transversal nonmassive mode, identified as
Nambu-Goldstone, and a massive longitudinal mode. Besides the Lorentz symmetry,
this model also exhibits gauge symmetry violation. To restore the gauge
symmetry, we introduce the Stueckelberg field and calculate the two-point
function by employing the principal-value (PV) prescription. The result is
nontransversal, leading to a massive excited mode.",2307.14252v1
2023-07-30,Constructing Berry-Maxwell equations with Lorentz invariance and Gauss' law of Weyl monopoles in 4D energy-momentum space,"We present the construction of a reciprocal electromagnetic field by
extending the Berry curvatures from momentum space into four-dimensional (4D)
energy-momentum space. The resulting governing equations, termed Berry-Maxwell
equations, are derived, by incorporating Lorentz invariance to constrain the
parameter space of energy-momentum. Notably, these Berry-Maxwell equations
exhibit dual and self-dual structures compared to the Maxwell equations
governing conventional electromagnetic fields. Furthermore, we demonstrate that
the very existence of Berry-Maxwell equations is independent of the geometrical
phase of matter waves, implying that they cannot be directly derived from the
Schrodinger equation. Consequently, we propose the reciprocal electromagnetic
field as a physical reality, rooted in the fundamental principles of special
relativity and Gauss's law of Weyl monopoles. To validate our theory
experimentally, we outline three potential effects for verification: (i)
Lorentz boost of a Weyl monopole, (ii) reciprocal Thouless pumping, and (iii)
plane-wave solutions of Berry-Maxwell equations.",2308.00612v1
2023-08-03,Comprehensive analysis on photon-electron Lorentz-violation parameter plane,"Large High Altitude Air Shower Observatory~(LHAASO) opens the window of
ultra-high-energy~(UHE) photon detection, broadens the path of testing basic
physical concept such as Lorentz symmetry, and brings possibility of potential
high-energy physical phenomenon research such as photon decay and electron
decay. Currently, the UHE photons from LHAASO observation set strict
constraints on photon and electron Lorentz symmetry violation~(LV) effects. To
obtain a global impression of the photon-electron LV parameter plane, we make a
detailed analysis for photon decay and electron decay. Our discussion gives the
corresponding decay thresholds and energy-momentum distributions in different
LV parameter configurations. We get corresponding constraints on photon LV
parameter, electron LV parameter and the photon-electron LV parameter plane
from LHAASO observation. For the space allowed for LV effect, that is beyond
relativity, we also provide corresponding boundaries from LHAASO observation.",2308.02021v2
2023-08-25,Anisotropic Conformal Dark Gravity on the Lorentz Tangent Bundle Spacetime,"In this work we investigate the anisotropic conformal structure of the
gravitational field incorporating dark gravity in a generalized Lagrange
geometric framework on the Lorentz tangent bundle and we present two
applications; the anisotropic conformal Minkowski spacetime and the anisotropic
conformal FLRW cosmology. In the first application, the conformal factor
induces an anisotropic conformal de-Sitter-like space with extra curvature
which causes extra gravity and allows for Sasaki-type Finsler-like structures
which could potentially describe certain gravitational phenomena in a more
extended form. The cosmological properties of the model are also studied using
a FLRW metric structure for the underlying base manifold in the second
application, where we derive generalized Friedmann-like equations for the
horizontal subspace of the Lorentz tangent bundle spacetime that reduce under
certain conditions to those given by A. Triantafyllopoulos and P. C. Stavrinos
(2018) [Class. Quantum Grav. 35 085011] as well as those of general relativity.",2308.13308v1
2023-08-31,Yukawa-Lorentz Symmetry in Non-Hermitian Dirac Materials,"We propose a general construction of symmetry protected Lorentz invariant
non-Hermitian (NH) Dirac semimetals (DSMs), realized by invoking masslike
anti-Hermitian Dirac operators to its Hermitian counterpart. They feature
purely real or imaginary isotropic linear band dispersion, yielding a vanishing
density of states. Dynamic mass orderings in NH DSMs thus take place for strong
Hubbardlike local interactions through a quantum phase transition where nodal
NH Dirac quasiparticles are strongly coupled with bosonic order-parameter
fluctuations, hosting a non-Fermi liquid, beyond which the system becomes an
insulator. Depending on the internal Clifford algebra between the NH Dirac
operator and candidate mass order-parameter, the resulting quantum critical
fluid either remains coupled with the environment or recovers full Hermiticity
by decoupling from the bath, while always enjoying an emergent Yukawa-Lorentz
symmetry in terms of a unique velocity. We showcase the competition between
such mass orderings, their hallmarks on quasiparticle spectra in the ordered
phases, and the relevance of our findings in correlated designer NH Dirac
materials.",2308.16907v1
2023-09-07,"On global well-posedness, scattering and other properties for infinity energy solutions to inhomogeneous NLS Equation","In this work, we consider the inhomogeneous nonlinear Schr\""odinger (INLS)
equation in $\mathbb{R}^n$ \begin{align} i\partial_t u + \Delta u + \gamma
|x|^{-b}|u|^{\alpha} u = 0, \end{align} where $\gamma=\pm 1$, and $\alpha$ and
$b$ are positive numbers. Our main focus is to estabilish the global
well-posedness of the INLS equation in Lorentz spaces for $0<b<2$ and
$\alpha<\frac{4-2b}{N-2}$. To achieve this, we use Strichartz estimates in
Lorentz spaces $L^{r,q}(\R^n)$ combined with a fixed point argument. Working on
Lorentz space setting instead the classical $L^p$ is motivated by the fact that
the potential $|x|^{-b}$ does not belong the usual $L^p$-space. As a
consequence of the ideas developed here on the global solution study we obtain
some other properties for INLS, such as, existence of self-similar solutions,
scattering, wave operators and assymptotic stability.",2309.04029v1
2023-09-15,Relativistic Spherical Shocks in Expanding Media,"We investigate the propagation of spherically symmetric shocks in
relativistic homologously expanding media with density distributions following
a power-law profile in their Lorentz factor. That is, $\rho_{ej} \propto
t^{-3}\gamma_{e}(R,t)^{-\alpha}$, where $\rho_{ej}$ is the medium proper
density, $\gamma_{e}$ is its Lorentz factor, $\alpha>0$ is constant and $t$,
$R$ are the time and radius from the center. We find that the shocks behavior
can be characterized by their proper velocity, $U'=\Gamma_s'\beta_s'$, where
$\Gamma_s'$ is the shock Lorentz factor as measured in the immediate upstream
frame and $\beta_s'$ is the corresponding 3-velocity. While generally, we do
not expect the shock evolution to be self-similar, for every $\alpha>0$ we find
a critical value $U'_c$ for which a self-similar solution with constant $U'$
exists. We then use numerical simulations to investigate the behavior of
general shocks. We find that shocks with $U'>U'_c$ have a monotonously growing
$U'$, while those with $U'<U'_c$ have a decreasing $U'$ and will eventually die
out. Finally, we present an analytic approximation, based on our numerical
results, for the evolution of general shocks in the regime where $U'$ is
ultra-relativistic.",2309.08309v1
2023-09-27,Measurement-based Lorentz-covariant Bohmian trajectories of interacting photons,"In a recent article [Foo et. al., Nature Comms. 13, 2 (2022)], we devised a
method of constructing the Lorentz-covariant Bohmian trajectories of single
photons via weak measurements of the photon's momentum and energy. However,
whether such a framework can consistently describe multiparticle interactions
remains to be seen. Here, we present a nontrivial generalisation of our
framework to describe the relativistic Bohmian trajectories of two interacting
photons exhibiting nonclassical interference due to their indistiguishability.
We begin by deriving the average velocity fields of the indistinguishable
photons using a conditional weak measurement protocol, with detectors that are
agnostic to the identity of the respective photons. We demonstrate a direct
correspondence between the operationally-derived trajectories with those
obtained using a position- and time-symmetrised multiparticle Klein-Gordon
wavefunction, whose dynamics are manifestly Lorentz-covariant. We propose a
spacetime metric that depends nonlocally on the positions of both particles as
a curvature based interpretation of the resulting trajectories. Contrary to
prior expectations, our results demonstrate a consistent trajectory-based
interpretation of relativistic multiparticle interactions in quantum theory.",2309.16011v1
2023-12-13,$S$-matrix positivity without Lorentz invariance: a case study,"We investigate the analytic structure of scattering amplitudes in theories in
which Lorentz invariance is spontaneously broken. We do so by computing and
studying the S-matrix for a simple example: a superfluid described by a complex
scalar with quartic interactions. The computation is confined to tree-level,
for there are no absolutely stable single-particle states, though the lifetime
can be made long by lowering the chemical potential. For the $2 \to 2$
amplitude in center-of-mass configurations, not only is crossing symmetry
violated, there appears a {\it tree level} branch cut for unphysical
kinematics. Its appearance is a consequence of non-analyticity in the
dispersion relation. The branch point defines a new scale in the problem, which
scales inversely with the chemical potential. In this example, even derivatives
of the forward amplitude are positive while odd derivatives are negative. This
pattern can be understood in a general way in the limit of a small chemical
potential, or weak Lorentz breaking.",2312.08440v1
2023-12-17,Simulating Electromagnetic Cascades with Lorentz Invariance Violation,"Lorentz invariance violation (LIV) is a phenomenon featuring in various
quantum gravity models whereby Lorentz symmetry is broken at high energies,
potentially impacting the behaviour of particles and their interactions. Here
we investigate the phenomenology of LIV within the context of gamma-ray-induced
electromagnetic cascades. We conduct detailed numerical simulations to explore
the expected manifestations of LIV on gamma-ray fluxes, taking into account
relevant effects such as pair production and inverse Compton scattering.
Additionally, we consider processes forbidden in the Standard Model, namely
vacuum Cherenkov emission and photon decay. Our analysis reveals that these
modifications result in distinct characteristics within the measured particle
fluxes at Earth, which have the potential to be observed in high-energy
gamma-ray observations.",2312.10803v1
2023-12-19,Long time behaviour of the solution of Maxwell's equations in dissipative generalized Lorentz materials (II) A modal approach,"This work concerns the analysis of electromagnetic dispersive media modelled
by generalized Lorentz models. More precisely, this paper is the second of two
articles dedicated to the long time behaviour of solutions of Maxwell's
equations in dissipative Lorentz media, via the long time decay rate of the
electromagnetic energy for the corresponding Cauchy problem. In opposition to
the frequency dependent Lyapunov functions approach used in [Cassier, Joly,
Rosas Mart\'inez, Z. Angew. Math. Phys. 74 (2023), 115], we develop a method
based on the spectral analysis of the underlying non-self-adjoint operator of
the model. Although more involved, this approach is closer to physics, as it
uses the dispersion relation of the model, and has the advantage to provide
more precise and more optimal results, leading to distinguish the notion of
weak and strong dissipation.",2312.12231v1
2023-12-27,Quasinormal modes and greybody factor of a Lorentz-violating black hole,"Recently, a static spherically symmetric black hole solution was found in
gravity nonminimally coupled a background Kalb-Ramond field. The Lorentz
symmetry is spontaneously broken when the Kalb-Ramond field has a nonvanishing
vacuum expectation value. In this work, we focus on the quasinormal modes and
greybody factor of this black hole. The master equations for the perturbed
scalar field, electromagnetic field, and gravitational field can be written
into a uniform form. We use three methods to solve the quasinormal frequencies
in the frequency domain. The results agree well with each other. The time
evolution of a Gaussian wave packet is studied. The quasinormal frequencies
fitted from the time evolution data agree well with that of frequency domain.
The greybody factor is calculated by Wentzel-Kramers-Brillouin (WKB) method.
The effect of the Lorentz-violating parameter on the quasinormal modes and
greybody factor are also studied.",2312.16605v1
2024-01-11,Generalized Drude-Lorentz Model Complying with the Singularity Expansion Method,"Deriving analytical expressions of dielectric permittivities is required for
numerical and physical modeling of optical systems and the soar of
non-hermitian photonics motivates their prolongation in the complex plane.
Analytical models are based on the association of microscopic models to
describe macroscopic effects. However, the question is to know whether the
resulting Debye Drude Lorentz models are not too restrictive. Here we show that
the permittivity must be treated as a meromorphic transfer function that
complies with the requirements of complex analysis. This function can be
naturally expanded on a set of complex singularities. This singularity
expansion of the dielectric permittivity allows us to derive a generalized
expression of the Debye Drude Lorentz model that complies with the requirements
of complex analysis and the constraints of physical systems. We show that the
complex singularities and other parameters of this generalized expression can
be retrieved from experimental data acquired along the real frequency axis. The
accuracy of this expression is assessed for a wide range of materials including
metals, 2D materials and dielectrics, and we show how the distribution of the
retrieved poles helps in characterizing the materials.",2401.05756v1
2024-01-28,Pauli-Villars regularization of Kaluza-Klein Casimir energy with Lorentz symmetry,"The Pauli-Villars regularization is appropriate to discuss the UV sensitivity
of low-energy observables because it mimics how the contributions of new
particles at high energies cancel large quantum corrections from the light
particles in the effective field theory. We discuss the UV sensitivity of the
Casimir energy density and pressure in an extra-dimensional model in this
regularization scheme, and clarify the condition on the regulator fields to
preserve the Lorentz symmetry of the vacuum state. Some of the conditions are
automatically satisfied in spontaneously-broken supersymmetric models, but
supersymmetry is not enough to ensure the Lorentz symmetry. We show that the
necessary regulators can be introduced as bulk fields. We also evaluate the
Casimir energy density with such regulators, and its deviation from the result
obtained in the analytic regularization.",2402.00056v1
2024-02-06,Material boundaries in Carroll-Field-Jackiw Lorentz-violating electrodynamics,"This paper investigates certain aspects of the CPT-odd photon sector of the
minimal Standard Model Extension (SME) in the presence of a perfectly
conducting plate (perfect mirror). The considered sector is described by
Carroll-Field-Jackiw (CFJ) electrodynamics, where Lorentz violation is due to
the presence of a single background vector denoted as
$\left(k_{AF}\right)^{\mu}$, which we treat perturbatively up to second order.
Specifically, we derive the modified propagator for the electromagnetic field
due to the presence of the perfect mirror, and we study the corresponding
interaction between the mirror and a stationary point-like charge. Our results
reveal that when the charge is positioned near the mirror, a spontaneous torque
emerges, which is a unique effect of Lorentz symmetry breaking. Additionally,
we demonstrate that the image method for this theory is applicable when the
background vector has only the component perpendicular to the mirror.",2402.04133v1
2024-02-20,An exact stationary axisymmetric vacuum solution within a metric--affine bumblebee gravity,"Within the framework of the spontaneous Lorentz symmetry breaking, we
consider a metric--affine generalization of the gravitational sector of the
Standard--Model Extension (SME), including the Lorentz--violating (LV)
coefficients $u$ and $s^{\mu\nu}$. In this model, we derive the modified
Einstein field equations in order to obtain a new axisymmetric vacuum spinning
solution for a particular bumblebee's profile. Such a solution has the
remarkable property of incorporating the effects of Lorentz symmetry breaking
(LSB) through the LV dimensionless parameter $X=\xi b^2$, as the LSB is turned
off, $X=0$, we recover the well--established result, the Kerr solution, as
expected. Afterwards, we calculate the geodesics, the radial acceleration and
thermodynamic quantities for this new metric. We also estimate an upper bound
for $X$ by using astrophysical data of the advance Mercury's perihelion.",2402.13014v1
2024-02-21,Two-dimensional Lorentz-violating Casimir effect,"In this study, we consider the four-dimensional Maxwell electrodynamics
extended with CPT-even Myers-Pospelov Lorentz-violating dimension-six operators
to investigate the associated two-dimensional properties in the context of
quantum vacuum fluctuation effects, namely, the Casimir effect. Upon projecting
out the 4D theory down to a 2D theory we obtain analogs of these operators
leading to a modified dispersion relation in a Lorentz invariance violation
(LIV) scalar model equivalent to the electromagnetic theory. By making use of
the modified dispersion relation, we derive exact analytic expressions for the
Casimir energy and force induced by imposing Dirichlet boundary conditions on
the scalar field. In the regime where the LIV parameter becomes very small, we
recover known results for the Casimir energy and force plus correction terms
due to the LIV.",2402.13972v2
2024-03-22,Galilean relativity and wave-particle duality imply the Schrödinger equation,"We show that the Schr\""odinger equation can be derived assuming the Galilean
covariance of a generic wave equation and the validity of the de Broglie's
wave-particle duality hypothesis. We also obtain from this set of assumptions
the transformation law for the wave function under a Galilean boost and prove
that complex wave functions are unavoidable for a consistent description of a
physical system. The extension to the relativistic domain of the above analysis
is also provided. We show that Lorentz covariance and wave-particle duality are
consistent with two different transformation laws for the wave function under a
Lorentz boost. This leads to two different wave equations, namely, the
Klein-Gordon equation and the Lorentz covariant Schr\""odinger equation.",2403.15555v1
2024-04-03,The Relativistic Rotation Transformation and the Observer Manifold,"We show that relativistic rotation transformations represent transfer maps
between the laboratory system and a local observer on an observer manifold,
rather than an event manifold, in the spirit of C-equivalence. Rotation is,
therefore, not a parameterised motion on a background space or spacetime, but
is determined by a particular sequence of tetrads related by specific special
Lorentz transformations or boosts. Because such Lorentz boosts do not form a
group, these tetrads represent distinct observers that cannot put together
their local descriptions into a manifold in the usual sense. The choice of
observer manifold depends on the dynamical situation under consideration, and
is not solely determined by the kinematics. Three examples are given:
Franklin's rotation transformation for uniform plane rotation, the Thomas
precession of a vector attached to an electron, and the motion of a charged
particle in an electromagnetic field. In each case, at each point of its
trajectory, there is a distinguished tetrad and a special Lorentz
transformation that maps Minkowski space to the spacetime of the local observer
on the curve.",2404.05744v1
1995-02-09,A linear thermohaline oscillator driven by stochastic atmospheric forcing,"The interdecadal variability of a stochastically forced four-box model of the
oceanic meridional thermohaline circulation (THC) is described and compared to
the THC variability in the coupled ocean-atmosphere GCM of Delworth, Manabe,
and Stouffer (1993). The box model is placed in a linearly stable thermally
dominant mean state under mixed boundary conditions. A linear stability
analysis of this state reveals one damped oscillatory THC mode in addition to
purely damped modes. The variability of the model under a moderate amount of
stochastic forcing, meant to emulate the random variability of the atmosphere
affecting the coupled model's interdecadal THC variability, is studied. A
linear interpretation, in which the damped oscillatory mode is of primary
importance, is sufficient for understanding the mechanism accounting for the
stochastically forced variability. Direct comparison of the variability in the
box model and coupled GCM reveals common qualitative aspects. Such a comparison
supports, although does not verify, the hypothesis that the coupled model's THC
variability can be interpreted as the result of atmospheric weather exciting a
linear damped oscillatory THC mode.",9502002v2
1993-09-30,The metal systems in Q0000--2619 at high resolution,"We have obtained high, 11 and 14 \kms, and medium, 40 and 53 \kms, resolution
spectra of the $z_{em} = 4.11$ quasar Q0000--2619 covering the range 4400 \AA\
to 9265 \AA . We identify nine metal absorption systems, of which four were
previously known. A fifth previously suggested system at $z_{abs} \approx
3.409$ (Turnshek et al~ 1991) is ruled out by our data. Two of the eight
systems for which the \lya~ line is in the observable range have a damped \lya~
line. Six of the nine systems show evidence for complex sub--component
structure. At our resolution and S/N we identify a total of 21 sub--components
in the nine systems. Five of the nine systems (11 of the 21 components) fall
within the $\pm 5000$ \kms~ range of the emission redshift, and are hence
classified as \zae~ absorbers. For the two damped systems we find metal
abundances of $\leq 1$% and $\leq 8$% of solar values at redshifts of 3.0541
and 3.3901 respectively. These upper limits are consistent with what would be
expected from previous determinations at lower redshifts, and our data are
hence compatible with earlier conclusions that no evidence is yet found for
chemical evolution of intervening damped and Lyman limit absorbers. For the
\zae~ systems we found indications of metallicities comparable to, and even in
excess of solar values. These much higher values compared to the damped
systems, are in favour of the intrinsic hypothesis for these systems.",9309053v1
1994-12-27,The z=0.8596 Damped Lyman Alpha Absorbing Galaxy Toward PKS 0454+039,"We present {\it Hubble Space Telescope} and ground--based data on the
$z_{abs}=0.8596$ metal line absorption system along the line of sight to PKS
0454+0356. The system is a moderate redshift damped Lyman alpha system, with
${\rm N(HI)}=(5.7\pm0.3)\times10^{20}$~cm$^{-2}$ as measured from the {\it
Faint Object Spectrograph} spectrum. We also present ground--based images which
we use to identify the galaxy which most probably gives rise to the damped
system; the most likely candidate is relatively underluminous by QSO absorber
standards ($M_B \sim -19.0$ for $q_0=0.5$ and $H_0=50$ \kms Mpc$^{-1}$), and
lies $\sim 8.5h^{-1}$ kpc in projection from the QSO sightline. Ground--based
measurements of Zn~II, Cr~II, and Fe~II absorption lines from this system allow
us to infer abundances of [Zn/H]=$-1.1$, [Cr/H]=$-1.2$, and [Fe/H]=$-1.2$,
indicating overall metallicity similar to damped systems at $z >2$, and that
the depletion of Cr and Fe onto dust grains may be even {\it less} important
than in many of the high redshift systems of comparable metallicity. Limits
previously placed on the 21-cm optical depth in the $z=0.8596$ system, together
with our new N(H~I) measurement, suggest a very high spin temperature for the
H~I, $T_S >> 580$ K.",9412093v2
1995-05-17,GRAVITATIONAL LENSING OF QUASARS BY THEIR DAMPED LYMAN-ALPHA ABSORBERS,"Damped Lyman-alpha absorbers are believed to be associated with galactic
disks. We show that gravitational lensing can therefore affect the statistics
of these systems. First, the magnification bias due to lensing raises faint
QSOs above a given magnitude threshold and thereby enhances the probability for
observing damped absorption systems. Second, the bending of light rays from the
source effectively limits the minimum impact parameter of the line-of-sight
relative to the center of the absorber, thus providing an upper cut-off to the
observed neutral hydrogen (HI) column density. The combination of these effects
yields a pronounced peak in the observed abundance of absorbers with high
column densities (>2*10^{21} cm^{-2}) and low redshifts (z<1). The inferred
value of the cosmological density parameter of neutral hydrogen, Omega_{HI},
increases with increasing redshift and luminosity of the sources even if the
true HI density remains constant. This trend resembles the observed evolution
of Omega_{HI}(z). Damped Lyman-alpha absorbers with column densities >10^{21}
cm^{-2} and redshifts 0.5<z<1 are reliable flags for lensed QSOs with a close
pair of images separated by 0.3 arcsec. Detection of these gravitational
lensing signatures with the Hubble Space Telescope can be used to constrain the
depth of the absorber potential-wells and the cosmological constant.",9505078v1
1996-08-22,APM z>4 QSO Survey: Distribution and Evolution of High Column Density HI Absorbers,"Eleven candidate damped Lya absorption systems were identified in 27 spectra
of the quasars from the APM z>4 survey covering the redshift range
2.8<z(abs)<4.4 (8 with z(abs)>3.5). High resolution echelle spectra (0.8A FWHM)
have been obtained for three quasars, including 2 of the highest redshift
objects in the survey. Two damped systems have confirmed HI column densities of
N(HI) >= 10^20.3 atoms cm^-2, with a third falling just below this threshold.
We have discovered the highest redshift damped Lya absorber known at z=4.383 in
QSO BR1202-0725. The APM QSOs provide a substantial increase in the redshift
path available for damped surveys for z>3. We combine this high redshift sample
with other quasar samples covering the redshift range 0.008 < z < 4.7 to study
the redshift evolution and the column density distribution function for
absorbers with log N(HI)>=17.2. In the HI column density distribution
f(N)=kN^-beta we find evidence for breaks in the power law, flattening for
17.2< log N(HI)<21 and steepening for log N(HI)>21.2. The column density
distribution function for the data with log N(HI)>=20.3 is better fit with the
form f(N)=(f*/N*)(N/N*)^-beta exp(-N/N*). Significant redshift evolution in the
number density per unit redshift is evident in the higher column density
systems with an apparent decline in N(z) for z>3.5.",9608146v1
1997-05-16,Testing Cosmological Models Against the Abundance of Damped Lyman-Alpha Absorbers,"We calculate the number of damped Lyman-alpha absorbers expected in various
popular cosmological models as a function of redshift and compare our
predictions with observed abundances. The Press-Schechter formalism is used to
obtain the distribution of halos with circular velocity in different
cosmologies, and we calibrate the relation between circular velocity and
absorption cross-section using detailed gas dynamical simulations of a
``standard'' cold dark matter (CDM) model. Because of this calibration, our
approach makes more realistic assumptions about the absorption properties of
collapsed objects than previous, analytic calculations of the damped
Lyman-alpha abundance. CDM models with Omega_0=1, H_0=50, baryon density
Omega_b=0.05, and scale-invariant primeval fluctuations reproduce the observed
incidence and redshift evolution of damped Lyman-alpha absorption to within
observational uncertainty, for both COBE normalization (sigma_8=1.2) and a
lower normalization (sigma_8=0.7) that better matches the observed cluster
abundance at z=0. A tilted (n=0.8, sigma_8=0.7) CDM model tends to underproduce
absorption, especially at z=4. With COBE normalization, a CDM model with
Omega_0=0.4, Omega_{Lambda}=0.6 gives an acceptable fit to the observed
absorption; an open CDM model is marginally acceptable if Omega_0 is at least
0.4 and strongly inconsistent with the z=4 data if Omega_0=0.3. Mixed dark
matter models tend not to produce sufficient absorption, being roughly
comparable to tilted CDM models if Omega_{nu} = 0.2 and failing drastically if
Omega_{nu} = 0.3.",9705118v1
1997-05-28,Zinc and Chromium Abundances in a Third Damped Lyman alpha System at Intermediate Redshift,"We have determined the metallicity of the $z_{abs} = 1.0093$ damped Lyman
alpha system in the bright QSO EX 0302-223; this is only the third such
measurement at redshifts $z \simlt 1$. Unlike the previous two cases, we find
that the abundance of Zn is only a factor of $\sim 2$ lower than in the
Galactic interstellar medium today and is entirely compatible with the typical
metallicity of stars in the Milky Way disk at a look-back time of 9.5 Gyrs.
Although the galaxy responsible for producing the absorption system has yet to
be positively identified, our observations show that galaxies on a chemical
evolution path similar to that of the Milky Way do contribute to the damped
Lyman alpha population at intermediate redshifts. Cr is 2.5 times less abundant
than Zn, presumably because of depletion onto dust; however, the degree of
depletion is less severe than in diffuse interstellar clouds in the disk of our
Galaxy and in the Magellanic Clouds. Evidently, the interstellar environment in
damped Lyman alpha galaxies is less conducive to the formation and survival of
dust grains (and molecular hydrogen), but the physical processes at the root of
this effect have yet to be clarified.",9705222v1
1998-11-18,The Closest Damped Lyman Alpha System,"A difficulty of studying damped Lyman alpha systems is that they are distant,
so one knows little about the interstellar medium of the galaxy. Here we report
upon a damped Lyman alpha system in the nearby galaxy NGC 4203, which is so
close (v_helio = 1117 km/s) and bright (B_o = 11.62) that its HI disk has been
mapped. The absorption lines are detected against Ton 1480, which lies only
1.9' (12 h_50 kpc) from the center of NGC 4203. Observations were obtained with
the Faint Object Spectrograph on HST (G270H grating) over the 2222-3277
Angstrom region with 200 km/s resolution. Low ionization lines of Fe, Mn, and
Mg were detected, leading to metallicities of -2.29, < -0.68, and > -2.4, which
are typical of other damped Lyman alpha systems, but well below the stellar
metallicity of this type of galaxy. Most notably, the velocity of the lines is
1160 +- 10 km/s, which is identical to the HI rotational velocity of 1170 km/s
at that location in NGC 4203, supporting the view that these absorption line
systems can be associated with the rotating disks of galaxies. In addition, the
line widths of the Mg lines give an upper limit to the velocity dispersion of
167 km/s, to the 99% confidence level.",9811274v1
1999-07-29,Ionized Gas in Damped Lyman-alpha Systems and Its Effects on Elemental Abundance Studies,"Recent high-resolution observations of metal absorption lines in
high-redshift damped Ly-alpha systems have shown that Al III, a tracer of
moderately-ionized gas, very often has a velocity structure indistinguishable
from that of low-ionization gas. Regions of ionized and neutral hydrogen in
these systems are likely cospatial. The higher-ionization Si IV and C IV
absorption shows a much weaker or non-existent correlation with the low
ionization material, implying that the regions traced by Al III are
photoionized by a soft (stellar) spectrum, by a hard (power law) spectrum with
a very low ionization parameter, or a combination of both. We discuss the
ionization of the damped Ly-alpha systems and use photoionization equilibrium
models to make quantitative estimates of its effects on abundance studies in
these systems. We show that ionization effects may be large enough to account
for the observed dispersion in absolute metal abundances in damped Ly-alpha
systems, causing systematically higher abundances in lower column density
systems. The observed Si^+/Fe^+ and Zn^+/Cr^+ ratios may systematically
overestimate the intrinsic Si/Fe and Zn/Cr ratios, respectively, if ionized gas
is present in these systems, thereby mimicking the effects of alpha-element
enrichment or dust depletion.",9907428v1
1999-11-09,Detection of Warm and Cold Phases of the Neutral ISM in a Damped Ly-alpha Absorber,"We present a detailed study of the HI 21cm absorption system at z=0.0912
towards the radio quasar B0738+313. The uncommonly narrow main absorption line
and weak secondary line are resolved for the first time. In addition we find it
necessary to add a third, broader shallow component to obtain a good fit to the
spectrum. Although the harmonic mean spin temperature calculated by comparison
of the 21cm lines to the damped Ly-alpha line is T_s = 775 K, the thermal
kinetic temperatures of the two narrow components, calculated from their
widths, are much lower: T_k \leq 297 and \leq 103 K respectively. This is the
first case of a redshifted absorption system for which T_k is measured to be
less than T_s. We discuss this result in the context of a two phase gas model,
in which the damped Ly-alpha gas is sensitive to a significant neutral column
density of warm phase gas as well as the cold phase gas of the narrow 21cm
lines. The third component is interpreted as representing the warm phase gas
with with T_k \leq 5050 K. The combined column density of the three 21cm
components is approximately equal to that derived from fits to the damped
Ly-alpha line.",9911142v1
2000-06-01,Crust-core coupling and r-mode damping in neutron stars: a toy model,"R-modes in neutron stars with crusts are damped by viscous friction at the
crust-core boundary. The magnitude of this damping, evaluated by Bildsten and
Ushomirsky (BU) under the assumption of a perfectly rigid crust, sets the
maximum spin frequency for a neutron star spun up by accretion in a Low-Mass
X-ray binary (LMXB). In this paper we explore the mechanical coupling between
the core r-modes and the elastic crust, using a toy model of a constant density
neutron star with a constant shear modulus crust. We find that, at spin
frequencies in excess of ~50 Hz, the r-modes strongly penetrate the crust. This
reduces the relative motion (slippage) between the crust and the core compared
to the rigid crust limit. We therefore revise down, by as much as a factor of
10^2-10^3, the damping rate computed by BU, significantly reducing the maximal
possible spin frequency of neutron star with a solid crust. The dependence of
the crust-core slippage on the spin frequency is complicated, and is very
sensitive to the physical thickness of the crust. If the crust is sufficiently
thick, the curve of the critical spin frequency for the onset of the r-mode
instability becomes multi-valued for some temperatures; this is related to the
avoided crossings between the r-mode and the higher-order torsional modes in
the crust. The critical frequencies are comparable to the observed spins of
neutron stars in LMXBs and millisecond pulsars.",0006028v1
2001-03-23,First Investigation of the Clustering Environment of Damped Lyman Alpha Absorbers at z=4,"We report the first observations of the clustering environment of damped
Lyman alpha absorption systems at z=4. Color selection and photometric
redshifts were used to select 44 candidate Lyman-break galaxies brighter than
I_AB=25.5 from deep BRI images of the 35 sq. arcmin field containing the quasar
BR 0951-04. Multislit spectroscopy of 35 candidate galaxies was performed and 8
of these candidates have been confirmed as z>3.5 Lyman-break galaxies. With
only BRI photometry, the photometric redshifts are quite accurate for the
spectroscopically confirmed galaxies but have a high rate of misclassification
due to color degeneracies between Lyman-break galaxies and low-redshift
ellipticals. Both of the z>3.5 galaxies found within 15'' of the quasar
line-of-sight appear to be causing absorption systems in the quasar spectrum.
We use a battery of statistical tests to look for clustering in the redshift
histogram of the z>3.5 galaxies but do not find measurable clustering of these
Lyman-break galaxies with the damped Lyman alpha absorbers. With a larger
sample of galaxies, our method should determine the cross-correlation between
these objects, which probes the bias and hence the mass of the damped Lyman
alpha absorbers.",0103387v2
2002-11-11,Damped Lyman alpha systems and galaxy formation models - II. High ions and Lyman limit systems,"We investigate a model for the high-ionization state gas associated with
observed damped Lyman-alpha systems, based on a semi-analytic model of galaxy
formation set within the paradigm of hierarchical structure formation. In our
model, the hot gas in halos and sub-halos gives rise to CIV absorption, while
the low-ionization state gas is associated with the cold gas in galaxies. The
model matches the distribution of CIV column densities and leads naturally to
kinematic properties that are in good agreement with the data.
  We examine the contribution of both hot and cold gas to sub-damped systems
and suggest that the properties of these systems can be used as an important
test of the model. We expect that sub-DLA systems will generally be composed of
a single gas disk and thus predict that they should have markedly different
kinematics than the damped systems.
  Finally, we find that hot halo gas produces less than one third of Lyman
limit systems at redshift three. We model the contribution of mini-halos (halos
with virial velocities < 35 km/s) to Lyman limit systems and find that they may
contain as much gas as is observed in these systems. However, if we adopt
realistic models of the gas density distribution we find that these systems are
not a significant source of Lyman limit absorption. Instead we suggest that
uncollapsed gas outside of virialized halos is responsible for most of the
Lyman limit systems at high redshift.",0211231v1
2003-05-16,The Age-Metallicity Relation of the Universe in Neutral Gas: The First 100 Damped Lya Systems,"We present accurate metallicity measurements for 121 damped Lya systems at
0.5<z<5 including ~50 new measurements from our recently published Echellette
Spectrograph and Imager surveys. This dataset is analysed to determine the
age-metallicity relation of neutral gas in the universe. Contrary to previous
datasets this sample shows statistically significant evolution in the mean
metallicity. The best linear fit rate to metallicity vs. redshift is -0.26 +/-
0.07 dex corresponding to approximately a factor of 2 every Gyr at z=3. The DLA
continue to maintain a floor in metallicity of ~1/700 solar independent of
observational effects. This metallicity threshold limits the prevalence of
primordial gas in high redshift galaxies and stresses the correspondence
between damped systems and star formation (i.e. galaxy formation). This floor
is significantly offset from the metallicity of the Lya forest and therefore we
consider it to be more related to active star formation within these galaxies
than scenarios of enrichment in the very early universe. Finally, we comment on
an apparent 'missing metals problem': the mean metallicity of the damped
systems is ~10x lower than the value expected from their observed star
formation history. This problem is evident in current theoretical treatments of
chemical evolution and galaxy formation; it may indicate a serious flaw in our
understanding of the interplay between star formation and metal production.",0305314v1
2003-09-24,WIMP matter power spectra and small scale power generation,"Dark Matter (DM) is generally assumed to be massive, cold and collisionless
from the structure formation point of view. A more correct statement however is
that DM indeed experiences collisional damping, but on a scale which is
supposed to be too small to be relevant for structure formation. The aim of
this paper is to present a Cold (although ``collisional'') Dark Matter particle
whose matter power spectrum is damped and see whether it is distinguishable
from standard candidates. To achieve this purpose, we calculate the collisional
damping and free-streaming scales of neutralinos and non conventional
candidates (say light particles heavier than ~1 MeV but lighter than O(10)
GeV). The latter can be considered as Cold Dark Matter (CDM) particles in the
sense that they become non relativistic before their thermal decoupling epoch.
Unlike neutralinos, however, their linear matter power spectrum can be damped
on scales of ~ 10^3 Msol due to their interactions. Since these scales are of
cosmological interest for structure formation, we perform a series of numerical
simulations to obtain the corresponding non linear matter power spectra
P(k)_{nl} at the present epoch. We show that because of small scale
regeneration, they all resemble each other at low redshifts, i.e. become very
similar to a typical CDM matter power spectrum on all but the smallest scales.
Therefore, even if lensing measurements at redshift below unity were to yield a
P(k)_{nl} consistent with CDM models, this would not constitute a sufficiently
robust evidence in favour of the neutralino to rule out alternative DM
candidates.",0309652v1
2004-03-16,The SDSS Damped Lya Survey: Data Release 1,"We present the results from an automated search for damped Lya (DLA) systems
in the quasar spectra of Data Release 1 from the Sloan Digital Sky Survey
(SDSS-DR1). At z~2.5, this homogeneous dataset has greater statistical
significance than the previous two decades of research. We derive a statistical
sample of 71 damped Lya systems (>50 previously unpublished) at z>2.1 and
measure HI column densities directly from the SDSS spectra. The number of DLA
systems per unit redshift is consistent with previous measurements and we
expect our survey has >95% completeness. We examine the cosmological baryonic
mass density of neutral gas Omega_g inferred from the damped Lya systems from
the SDSS-DR1 survey and a combined sample drawn from the literature. Contrary
to previous results, the Omega_g values do not require a significant correction
from Lyman limit systems at any redshift. We also find that the Omega_g values
for the SDSS-DR1 sample do not decline at high redshift and the combined sample
shows a (statistically insignificant) decrease only at z>4. Future data
releases from SDSS will provide the definitive survey of DLA systems at z~2.5
and will significantly reduce the uncertainty in Omega_g at higher redshift.",0403391v2
2006-06-28,Neutral gas density in Damped Lyman Alpha systems,"We estimate the intrinsic neutral gas density in Damped Lyman Alpha systems
($\Omega_{HI}^{(DLA)}$) in the redshift range $ 2.2 \lesssim z \lesssim 5$ from
the DLA SDSS DR_3 sample of optically selected quasars. We take into account
self-consistently the obscuration on background quasars due to the dust present
in Damped Lyman Alpha systems. We model the column density and redshift
distribution of these systems by using both a non-parametric and a parametric
approach. Under conservative assumptions on the dust content of Damped Lyman
$\alpha$ systems, we show that selection effects lead to underestimating the
intrinsic neutral gas density by at least $15\%$ with respect to the observed
neutral gas density. Over the redshift range $[2.2;5.5]$ we find
$\Omega_{HI}^{(DLA)}=0.97^{+0.08+0.28}_{-0.06-0.15} \cdot 10^{-3}$, where the
first set of error bars gives the $1\sigma$ random errors and the second set
gives the modeling uncertainty dependent on the fraction of metals in dust -
from 0\% to 50\%. This value compares with
$\Omega_{HI}^{(DLA)}=0.82^{+0.05}_{-0.05}$ ($1\sigma$ error bars), which is
obtained when no correction for dust is introduced. In the model with half of
the metals mass in dust we cannot constraint $\Omega_{HI}^{(DLA)}$ at a
confidence level higher than $90\%$. In this case there is indeed a probability
of about $10\%$ that the intrinsic column density distribution of DLA systems
is a power law $f(N_{HI}) \propto 1/N_{HI}^{~1.95}$. In contrast, with $25 \%$
of the metals in dust - the most realistic estimate - a power law is ruled out
at $99.5\%$ of confidence level.",0606693v1
2006-09-06,Sun-as-a-star observations: evidence for degree dependence of changes in damping of low-l p modes along the solar cycle,"We use 9.5-yr of BiSON Sun-as-a-star data to search for dependence of
solar-cycle parameter changes on the angular degree, l, of the data. The nature
of the Sun-as-a-star observations is such that for changes measured at fixed
frequency, or for changes averaged across the same range in frequency, any l
dependence present carries information on the latitudinal distribution of the
agent (i.e., the activity) responsible for those changes. We split the 9.5-yr
timeseries into contiguous 108-d pieces, and determine mean changes in the
damping of, power in, and energy supplied to the modes through the solar cycle.
We also apply a careful correction to account for the deleterious effects of
the ground-based BiSON window function on the results. From our full analysis
we obtain a marginally significant result for the damping parameter, where the
mean change is found to be weakest at l=0. The other parameters show hints of
some dependence in l. Our main conclusion is that the mean fractional
solar-cycle change in the l=0 damping rates is approximately 50 % smaller than
was previously assumed. It had been common practice to use an average over all
low-l modes; our downward revision of the radial-mode value has implications
for comparisons with models of the global solar cycle changes, which are
usually based on a spherically symmetric geometry.",0609156v2
1997-08-12,Coherence in the Quasi-Particle 'Scattering' by the Vortex Lattice in Pure Type-II Superconductors,"The effect of quasi-particle (QP) 'scattering' by the vortex lattice on the
de-Haas van-Alphen oscillations in a pure type-II superconductor is
investigated within mean field,asymptotic perturbation theory. Using a 2D
electron gas model it is shown that, due to a strict phase coherence in the
many-particle correlation functions, the 'scattering' effect in the asymptotic
limit ($\sqrt{E_F/\hbar\omega_c}\gg 1$) is much weaker than what is predicted
by the random vortex lattice model proposed by Maki and Stephen, which destroys
this coherence . The coherent many particle configuration is a collinear array
of many particle coordinates, localized within a spatial region with size of
the order of the magnetic length. The amplitude of the magnetization
oscillations is sharply damped just below $% H_{c2}$ because of strong
$180^{\circ}$ out of phase magnetic oscillations in the superconducting
condensation energy ,which tend to cancel the normal electron oscillations.
Within the ideal 2D model used it is found, however, that because of the
relative smallness of the quartic and higher order terms in the expansion, the
oscillations amplitude at lower fields does not really damp to zero, but only
reverses sign and remains virtually undamped well below $H_{c2}$. This
conclusion may be changed if disorder in the vortex lattice, or vortex lines
motion will be taken into account. The reduced QP 'scattering' effect may be
responsible for the apparent crossover from a strong damping of the dHvA
oscillations just below $H_{c2}$ to a weaker damping at lower fields observed
experimentally in several 3D superconductors.",9708088v1
1999-08-27,Electron Correlations in an Electron Bilayer at Finite Temperature: Landau Damping of the Acoustic Plasmon,"We report angle-resolved Raman scattering observations of the temperature
dependent Landau damping of the acoustic plasmon in an electron bilayer system
realised in a GaAs double quantum well structure. Corresponding calculations of
the charge-density excitation spectrum of the electron bilayer using forms of
the random phase approximation (RPA), and the static local field formalism of
Singwi, Tosi, Land and Sj\""{o}lander (STLS) extended to incorporate non-zero
electron temperature $T_{\rm e}$ and phenomenological damping, are also
presented. The STLS calculations include details of the temperature dependence
of the intra- and inter-layer local field factors and pair-correlation
functions. Good agreement between experiment and the various theories is
obtained for the acoustic plasmon energy and damping for $T_{\rm e} \lesssim
T_{\rm F}/2$, the Fermi temperature. However, contrary to current expectations,
all of the calculations show significant departures from our experimental data
for $T_{\rm e} \gtrsim T_{\rm F}/2$. From this, we go on to demonstrate
unambiguously that real local field factors fail to provide a physically
accurate description of exchange correlation behaviour in low dimensional
electron gases. Our results suggest instead that one must resort to a
{\em{dynamical}} local field theory, characterised by a {\em{complex}} field
factor to provide a more accurate description.",9908408v1
2000-10-02,"Comment on ""Magnetic Breakdown at High Fields: Semiclassical and Quantum Treatments""","We comment on the study of the spin-damping factor on the de Haas-van Alphen
(dHvA) discussed by Han et al. (Phys. Rev. Lett. 85, 1500 (2000)).",0010018v1
2002-03-11,Shubnikov - de Haas effect in the quantum vortex liquid state of the organic superconductor $κ$-(BEDT-TTF)$_{2}$Cu(NCS)$_{2}$,"We report the Shubnikov-de Haas (SdH) oscillations observed in the vortex
liquid state of the quasi two dimensional organic superconductor
$\kappa$-(BEDT-TTF)$_{2}$Cu(NCS)$_{2}$. The SdH oscillations can be observed
down to about 5 T at 0.5 K, where the flux flow resistivity becomes as small as
about 30 % of the normal state value. Below the upper critical field $H_{\rm
c2}$ of about 7 T, the additional damping of the SdH oscillation amplitude
appears, as well as that of the de Haas-van Alphen (dHvA) oscillations, with
respect to the normal state one which is described with the standard
Lifshitz-Kosevich formula. The magnitude of the additional damping near $H_{\rm
c2}$ is the same with that observed in the dHvA oscillations and well explained
by the theoretical predictions in consideration of fluctuations in the thermal
vortex liquid state. In the quantum fluctuation region at lower temperature,
however, only SdH effect shows the stronger damping than that of the dHvA
oscillations. The different magnetic field dependence of the additional damping
of the oscillation amplitude between the SdH and dHvA effects is discussed in
connection with the effect of the transport current on the short-range order of
vortices in the quantum vortex slush state reported at the same temperature and
magnetic field region.",0203228v2
2003-03-13,Vibrational sidebands and dissipative tunneling in molecular transistors,"Transport through molecular devices with strong coupling to a single
vibrational mode is considered in the case where the vibration is damped by
coupling to the environment. We focus on the weak tunneling limit, for which a
rate equation approach is valid. The role of the environment can be
characterized by a frictional damping term $\mysig(\omega)$ and corresponding
frequency shift. We consider a molecule that is attached to a substrate,
leading to frequency-dependent frictional damping of the single oscillator mode
of the molecule, and compare it to a reference model with frequency-independent
damping featuring a constant quality factor $Q$. For large values of $Q$, the
transport is governed by tunneling between displaced oscillator states giving
rise to the well-known series of the Frank-Condon steps, while at small $Q$,
there is a crossover to the classical regime with an energy gap given by the
classical displacement energy. Using realistic values for the elastic
properties of the substrate and the size of the molecule, we calculate $I$-$V$
curves and find qualitative agreement between our theory and recent experiments
on $C_{60}$ single-molecule devices.",0303236v3
2004-09-03,Weyl equation for temperature fields induced by attosecond laser pulses,"In this paper the Weyl equation for temperature field induced by laser beam
interaction with matter is proposed and solved. Depending on the scattering
mechanism the temperature field oscillate or is damped.
  Key words: Thermal processes, Weyl equation",0409076v1
2004-12-08,Spectroscopy of a driven solid-state qubit coupled to a structured environment,"We study the asymptotic dynamics of a driven spin-boson system where the
environment is formed by a broadened localized mode. Upon exploiting an exact
mapping, an equivalent formulation of the problem in terms of a quantum
two-state system (qubit) coupled to a harmonic oscillator which is itself
Ohmically damped, is found. We calculate the asymptotic population difference
of the two states in two complementary parameter regimes. For weak damping and
low temperature, a perturbative Floquet-Born-Markovian master equation for the
qubit-oscillator system can be solved. We find multi-photon resonances
corresponding to transitions in the coupled quantum system and calculate their
line-shape analytically. In the complementary parameter regime of strong
damping and/or high temperatures, non-perturbative real-time path integral
techniques yield analytic results for the resonance line shape. In both
regimes, we find very good agreement with exact results obtained from a
numerical real-time path-integral approach. Finally, we show for the case of
strong detuning between qubit and oscillator that the width of the $n$-photon
resonance scales with the $n$-th Bessel function of the driving strength in the
weak-damping regime.",0412194v2
1995-03-08,A NEW NUMERICAL APPROACH TO THE OSCILLATION MODES OF RELATIVISTIC STARS,"The oscillation modes of a simple polytropic stellar model are studied. Using
a new numerical approach (based on integration for complex coordinates) to the
problem for the stellar exterior we have computed the eigenfrequencies of the
highly damped w-modes. The results obtained agree well with recent ones of
Leins, Nollert and Soffel (1993) Specifically, we are able to explain why
several modes in this regime of the complex frequency plane could not be
identified within the WKB approach of Kokkotas and Schutz (1992). Furthermore,
we have established that the ``kink'' that was a prominent feature of the
spectra of Kokkotas and Schutz, but did not appear in the results of Leins {\em
et al.}, was a numerical artefact. Using our new numerical code we are also
able to compute, for the first time, several of the slowly damped (p) modes for
the considered stellar models. For very compact stars we find, somewhat
surprisingly, that the damping of these modes does not decrease monotonically
as one proceeds to higher oscillation frequencies. The existence of low-order
modes that damp away much faster than anticipated may have implications for
questions regarding stellar stability and the lifetime of gravitational-wave
sources. The present results illustrate the accuracy and reliability of the
complex-coordinate method and indicate that the method could prove to be of
great use also in problems involving rotating stars. There is no apparent
reason why the complex-coordinate approach should not extend to rotating stars,
whereas it is accepted that all previous methods will fail to do so.",9503014v1
1998-01-29,"On the gravitational, dilatonic and axionic radiative damping of cosmic strings","We study the radiation reaction on cosmic strings due to the emission of
dilatonic, gravitational and axionic waves. After verifying the (on average)
conservative nature of the time-symmetric self-interactions, we concentrate on
the finite radiation damping force associated with the half-retarded minus
half-advanced ``reactive'' fields. We revisit a recent proposal of using a
``local back reaction approximation'' for the reactive fields. Using
dimensional continuation as convenient technical tool, we find, contrary to
previous claims, that this proposal leads to antidamping in the case of the
axionic field, and to zero (integrated) damping in the case of the
gravitational field. One gets normal positive damping only in the case of the
dilatonic field. We propose to use a suitably modified version of the local
dilatonic radiation reaction as a substitute for the exact (non-local)
gravitational radiation reaction. The incorporation of such a local
approximation to gravitational radiation reaction should allow one to complete,
in a computationally non-intensive way, string network simulations and to give
better estimates of the amount and spectrum of gravitational radiation emitted
by a cosmologically evolving network of massive strings.",9801105v3
2004-10-15,A Nonlinear Coupling Network to Simulate the Development of the r-mode Instablility in Neutron Stars II. Dynamics,"Two mechanisms for nonlinear mode saturation of the r-mode in neutron stars
have been suggested: the parametric instability mechanism involving a small
number of modes and the formation of a nearly continuous Kolmogorov-type
cascade. Using a network of oscillators constructed from the eigenmodes of a
perfect fluid incompressible star, we investigate the transition between the
two regimes numerically. Our network includes the 4995 inertial modes up to n<=
30 with 146,998 direct couplings to the r-mode and 1,306,999 couplings with
detuning< 0.002 (out of a total of approximately 10^9 possible couplings).
  The lowest parametric instability thresholds for a range of temperatures are
calculated and it is found that the r-mode becomes unstable to modes with
13<n<15. In the undriven, undamped, Hamiltonian version of the network the rate
to achieve equipartition is found to be amplitude dependent, reminiscent of the
Fermi-Pasta-Ulam problem. More realistic models driven unstable by
gravitational radiation and damped by shear viscosity are explored next. A
range of damping rates, corresponding to temperatures 10^6K to 10^9K, is
considered. Exponential growth of the r-mode is found to cease at small
amplitudes, approximately 10^-4. For strongly damped, low temperature models, a
few modes dominate the dynamics. The behavior of the r-mode is complicated, but
its amplitude is still no larger than about 10^-4 on average. For high
temperature, weakly damped models the r-mode feeds energy into a sea of
oscillators that achieve approximate equipartition. In this case the r-mode
amplitude settles to a value for which the rate to achieve equipartition is
approximately the linear instability growth rate.",0410072v1
1997-02-20,Numerical study of plasmon properties in the SU(2)-Higgs model,"Using the (effective) classical approximation, we compute numerically
time-dependent correlation functions in the SU(2)-Higgs model around the
electroweak phase transition, for $m_H \approx m_W$. The parameters of the
classical model have been determined previously by the dimensional reduction
relations for time-independent correlators. The $H$ and $W$ correlation
functions correspond to gauge invariant fields. They show damped oscillatory
behavior from which we extract frequencies $\om$ and damping rates $\gm$. In
the Higgs phase the damping rates have roughly the values obtained in analytic
calculations in the quantum theory. In the plasma phase (where analytic
estimates for gauge invariant fields are not available), the damping rate
associated with $H$ is an order of magnitude larger than in the Higgs phase,
while the $W$ correlator appears to be overdamped, with a small rate. The
frequency $\om_H$ shows a clear dip at the transition. The results are
approximately independent of the lattice spacing, but this appears to be
compatible with the lattice spacing dependence expected from perturbation
theory.",9702017v2
2001-01-16,Nonlinear Landau damping of a plasmino in the quark-gluon plasma,"On the basis of the Blaizot-Iancu equations, which are a local formulation of
the hard thermal loop (HTL) equations of motion for soft fluctuating quark and
gluon fields and their induced sources, the coupled kinetic equations for
plasminos and plasmons are obtained. The equality of matrix elements for
nonlinear scattering of a plasmino by hard particles in covariant and temporal
gauges is established by using effective Ward identities. The model problem of
the interaction of two infinitely narrow packets with fermion and boson quantum
numbers is considered. The kinematical relations between wave vectors of the
plasmino and plasmon are derived, when the effective pumping over of the plasma
excitation energy from the fermion branch of plasma excitations to the boson
branch and vice versa occur. The expression for the nonlinear Landau damping
rate of a plasmino at rest is found, and a comparison with a plasmino damping
constant obtained within the framework of the hard thermal loop approximation
is made. The nonlinear Landau damping rate for normal quark excitations is
shown to diverge like $1/\sqrt{q^2}$ near the light cone where $q$ is a
four-momentum of excitations, and the improved Blaizot-Iancu equations removing
this divergence are proposed.",0101167v2
2003-12-15,Nonequilibrium pion dynamics near the critical point in a constituent quark model,"We study static and dynamical critical phenomena of chiral symmetry breaking
in a two-flavor Nambu--Jona-Lasinio constituent quark model. We obtain the
low-energy effective action for scalar and pseudoscalar degrees of freedom to
lowest order in quark loops and to quadratic order in the meson fluctuations
around the mean field. The \emph{static} limit of critical phenomena is shown
to be described by a Ginzburg-Landau effective action including \emph{spatial}
gradients. Hence \emph{static} critical phenomena is described by the
universality class of the O(4) Heisenberg ferromagnet. \emph{Dynamical}
critical phenomena is studied by obtaining the equations of motion for pion
fluctuations. We find that for $T<T_c$ the are stable long-wavelength pion
excitations with dispersion relation $\omega_{\pi}(k)=k$ described by isolated
pion poles. The residue of the pion pole vanishes near $T_c$ as $Z \propto
1/|\ln(1-T/T_c)|$ and long-wavelength fluctuations are damped out by Landau
damping on a time scale $t_\mathrm{rel}(k)\propto 1/k$, reflecting
\emph{critical slowing down} of pion fluctuations near the critical point. At
the critical point, the pion propagator features mass shell logarithmic
divergences which we conjecture to be the harbinger of a (large) dynamical
anomalous dimension. We find that while the \emph{classical spinodal} line
coincides with that of the Ginzburg-Landau theory, the growth rate of
long-wavelength spinodal fluctuations has a richer wavelength dependence as a
consequence of Landau damping. We argue that Landau damping prevents a
\emph{local} low energy effective action in terms of a derivative expansion in
real time.",0312185v2
2001-11-16,Resonances and superlattice pattern stabilization in two-frequency forced Faraday waves,"We investigate the role weakly damped modes play in the selection of Faraday
wave patterns forced with rationally-related frequency components m*omega and
n*omega. We use symmetry considerations to argue for the special importance of
the weakly damped modes oscillating with twice the frequency of the critical
mode, and those oscillating primarily with the ""difference frequency""
|n-m|*omega and the ""sum frequency"" (n+m)*omega. We then perform a weakly
nonlinear analysis using equations of Zhang and Vinals (1997, J. Fluid Mech.
336) which apply to small-amplitude waves on weakly inviscid, semi-infinite
fluid layers. For weak damping and forcing and one-dimensional waves, we
perform a perturbation expansion through fourth order which yields analytical
expressions for onset parameters and the cubic bifurcation coefficient that
determines wave amplitude as a function of forcing near onset. For stronger
damping and forcing we numerically compute these same parameters, as well as
the cubic cross-coupling coefficient for competing waves travelling at an angle
theta relative to each other. The resonance effects predicted by symmetry are
borne out in the perturbation results for one spatial dimension, and are
supported by the numerical results in two dimensions. The difference frequency
resonance plays a key role in stabilizing superlattice patterns of the SL-I
type observed by Kudrolli, Pier and Gollub (1998, Physica D 123).",0111039v2
2002-02-01,Time Domain Computation of a Nonlinear Nonlocal Cochlear Model with Applications to Multitone Interaction in Hearing,"A nonlinear nonlocal cochlear model of the transmission line type is studied
in order to capture the multitone interactions and resulting tonal suppression
effects. The model can serve as a module for voice signal processing, it is a
one dimensional (in space) damped dispersive nonlinear PDE based on mechanics
and phenomenology of hearing. It describes the motion of basilar membrane (BM)
in the cochlea driven by input pressure waves. Both elastic damping and
selective longitudinal fluid damping are present. The former is nonlinear and
nonlocal in BM displacement, and plays a key role in capturing tonal
interactions. The latter is active only near the exit boundary (helicotrema),
and is built in to damp out the remaining long waves. The initial boundary
value problem is numerically solved with a semi-implicit second order finite
difference method. Solutions reach a multi-frequency quasi-steady state.
Numerical results are shown on two tone suppression from both high-frequency
and low-frequency sides, consistent with known behavior of two tone
suppression. Suppression effects among three tones are demonstrated by showing
how the response magnitudes of the fixed two tones are reduced as we vary the
third tone in frequency and amplitude. We observe qualitative agreement of our
model solutions with existing cat auditory neural data. The model is thus
simple and efficient as a processing tool for voice signals.",0202004v3
2003-12-22,Intermittency is a consequence of turbulent transport in nonlinear systems,"Intermittent high-amplitude structures emerge in a damped and driven discrete
nonlinear Schroedinger equation whose solutions transport both energy and
particles from sources to sinks. These coherent structures are necessary for
any solution that has statistically stationary transport properties.",0312059v1
2004-06-17,Multi-frequency control of Faraday wave patterns,"We show how pattern formation in Faraday waves may be manipulated by varying
the harmonic content of the periodic forcing function. Our approach relies on
the crucial influence of resonant triad interactions coupling pairs of critical
standing wave modes with damped, spatio-temporally resonant modes. Under the
assumption of weak damping and forcing, we perform a symmetry-based analysis
that reveals the damped modes most relevant for pattern selection, and how the
strength of the corresponding triad interactions depends on the forcing
frequencies, amplitudes, and phases. In many cases, the further assumption of
Hamiltonian structure in the inviscid limit determines whether the given triad
interaction has an enhancing or suppressing effect on related patterns.
Surprisingly, even for forcing functions with arbitrarily many frequency
components, there are at most five frequencies that affect each of the
important triad interactions at leading order. The relative phases of those
forcing components play a key role, sometimes making the difference between an
enhancing and suppressing effect. In numerical examples, we examine the
validity of our results for larger values of the damping and forcing. Finally,
we apply our findings to one-dimensional periodic patterns obtained with
impulsive forcing and to two-dimensional superlattice patterns and
quasipatterns obtained with multi-frequency forcing.",0406034v1
1997-01-22,Shell Model for Warm Rotating Nuclei,"In order to provide a microscopic description of levels and E2 transitions in
rapidly rotating nuclei with internal excitation energy up to a few MeV, use is
made of a shell model which combines the cranked Nilsson mean-field and the
residual surface delta two-body force. The damping of collective rotational
motion is investigated in the case of a typical rare-earth nucleus, namely \Yb.
It is found that rotational damping sets in at around 0.8 MeV above the yrast
line, and the levels which form rotational band structures are thus limited. We
predict at a given rotational frequency existence of about 30 rotational bands
of various lengths, in overall agreement with the experimental findings. The
onset of the rotational damping proceeds quite gradually as a function of the
internal excitation energy. The transition region extends up to around 2 MeV
above yrast and it is characterized by the presence of scars of discrete
rotational bands which extend over few spin values and stand out among the
damped transitions, and by a two-component profile in the $E_\gamma -E_\gamma$
correlation. The important role played by the high-multipole components of the
two-body residual interaction is emphasized.",9701044v1
2005-04-21,Enhanced optical cooling of particle beams in storage rings,"The problem of enhanced optical cooling (EOC) of particle beams in storage
rings beyond the Robinson's damping criterion is discussed.",0504145v1
2005-10-21,Non-contact atomic force microscopy: Stability criterion and dynamical responses of the shift of frequency and damping signal,"The aim of this article is to provide a complete analysis of the behavior of
a noncontact atomic force microscope (NC-AFM). We start with a review of the
equations of motion of a tip interacting with a surface in which the stability
conditions are first revisited for tapping mode. Adding the equations of
automatic gain control (AGC), which insures constant amplitude of the
oscillations in the NC-AFM, to the equations of motion of the tip, a new
analytical stability criterion that involves proportional and integral gains of
AGC is deduced. Stationary solutions for the shift of frequency and for the
damping signal are obtained. Special attention is paid to the damping signal in
order to clarify its physical origin. The theoretical results are then compared
to those given by a virtual machine. The virtual machine is a set of equations
solved numerically without any approximation. The virtual machine is of great
help in understanding the dynamical behavior of the NC-AFM as images are
recorded. Transient responses of the shift in frequency and of the damping
signal are discussed in relation to the values of proportional and integral
gains of AGC.",0510192v1
1999-06-09,Quantum dynamics of a damped deformed oscillator,"The interaction of a quantum deformed oscillator with the environment is
studied deriving a master equation whose form strongly depends on the type of
deformation.",9906031v1
2006-06-15,Purity and decoherence in the theory of a damped harmonic oscillator,"For the generalized master equations derived by Karrlein and Grabert for the
microscopic model of a damped harmonic oscillator, the conditions for purity of
states are written, in particular for different initial conditions and
different types of damping, including Ohmic, Drude and weak coupling cases,
Agarwal and Weidlich-Haake models. It is shown that the states which remain
pure are the squeezed states with constant in time variances. For pure states,
the generalized nonlinear Schr\"" odinger-type equations corresponding to these
master equations are also obtained. Then the condition for purity of states of
a damped harmonic oscillator is considered in the framework of Lindblad theory
for open quantum systems. For a special choice of the environment coefficients,
the correlated coherent states with constant variances and covariance are shown
to be the only states which remain pure all the time during the evolution of
the considered system. In Karrlein-Grabert and Lindblad models, as well as in
the considered particular models, the expressions of the rate of entropy
production is written and it is shown that the states which preserve their
purity in time are also the states which minimize the entropy production and,
therefore, they are the most stable ones under evolution in the presence of the
environment and play an important role in the description of decoherence
phenomenon.",0606134v1
2007-04-29,Long Term Evolution of Magnetic Turbulence in Relativistic Collisionless Shocks: Electron-Positron Plasmas,"We study the long term evolution of magnetic fields generated by a
collisionless relativistic $e^+e^-$ shock which is initially unmagnetized. Our
2D particle-in-cell numerical simulations show that downstream of such a
Weibel-mediated shock, particle distributions are close to isotropic,
relativistic Maxwellians, and the magnetic turbulence is highly intermittent
spatially, with the non-propagating magnetic fields forming relatively isolated
regions with transverse dimension $\sim 10-20$ skin depths. These structures
decay in amplitude, with little sign of downstream merging. The fields start
with magnetic energy density $\sim (0.1-0.2)$ of the upstream kinetic energy
within the shock transition, but rapid downstream decay drives the fields to
much smaller values, below $10^{-3}$ of equipartition after $10^3$ skin depths.
  In an attempt to construct a theory that follows field decay to these smaller
values, we explore the hypothesis that the observed damping is a variant of
Landau damping in an unmagnetized plasma. The model is based on the small value
of the downstream magnetic energy density, which suggests that particle orbits
are only weakly perturbed from straight line motion, if the turbulence is
homogeneous. Using linear kinetic theory applied to electromagnetic fields in
an isotropic, relativistic Maxwellian plasma, we find a simple analytic form
for the damping rates, $\gamma_k$, in two and three dimensions for small
amplitude, subluminous electromagnetic fields. We find that magnetic energy
does damp due to phase mixing of current carrying particles as $(\omega_p
t)^{-q}$ with $q \sim 1$. (abridged)",0704.3832v2
2007-06-21,Production of a sterile species via active-sterile mixing: an exactly solvable model,"The production of a sterile species via active-sterile mixing in a thermal
medium is studied in an exactly solvable model. The \emph{exact} time evolution
of the sterile distribution function is determined by the dispersion relations
and damping rates $\Gamma_{1,2}$ for the quasiparticle modes. These depend on
$\wtg = \Gamma_{aa}/2\Delta E$, with $\Gamma_{aa}$ the interaction rate of the
active species in absence of mixing and $\Delta E$ the oscillation frequency in
the medium without damping. $\wtg \ll1,\wtg \gg 1$ describe the weak and strong
damping limits respectively. For $\wtg\ll1$, $\Gamma_1 = \Gamma_{aa}\cos^2\tm ;
\Gamma_{2}=\Gamma_{aa}\sin^2\tm$ where $\tm$ is the mixing angle in the medium
and the sterile distribution function \emph{does not} obey a simple rate
equation. For $\wtg \gg 1$, $\Gamma_1= \Gamma_{aa}$ and $\Gamma_2 = \Gamma_{aa}
\sin^22\tm/4\wtg^2$, is the sterile production rate. In this regime sterile
production is suppressed and the oscillation frequency \emph{vanishes} at an
MSW resonance, with a breakdown of adiabaticity. These are consequences of
quantum Zeno suppression. For active neutrinos with standard model interactions
the strong damping limit is \emph{only} available near an MSW resonance
\emph{if} $\sin\theta \lesssim \alpha_w$ with $\theta$ the vacuum mixing angle.
The full set of quantum kinetic equations for sterile production for arbitrary
$\wtg$ are obtained from the quantum master equation. Cosmological resonant
sterile neutrino production is quantum Zeno suppressed relieving potential
uncertainties associated with the QCD phase transition.",0706.3167v2
2007-08-02,Eccentricity evolution of giant planet orbits due to circumstellar disk torques,"The extrasolar planets discovered to date possess unexpected orbital
elements. Most orbit their host stars with larger eccentricities and smaller
semi-major axes than similarly sized planets in our own solar system do. It is
generally agreed that the interaction between giant planets and circumstellar
disks (Type II migration) drives these planets inward to small radii, but the
effect of these same disks on orbital eccentricity, e, is controversial.
Several recent analytic calculations suggest that disk-planet interactions can
excite eccentricity, while numerical studies generally produce eccentricity
damping. This paper addresses this controversy using a quasi-analytic approach,
drawing on several preceding analytic studies. This work refines the current
treatment of eccentricity evolution by removing several approximations from the
calculation of disk torques. We encounter neither uniform damping nor uniform
excitation of orbital eccentricity, but rather a function de/dt that varies in
both sign and magnitude depending on eccentricity and other solar system
properties. Most significantly, we find that for every combination of disk and
planet properties investigated herein, corotation torques produce negative
values of de/dt for some range in e within the interval [0.1, 0.5]. If
corotation torques are saturated, this region of eccentricity damping
disappears, and excitation occurs on a short timescale of less than 0.08 Myr.
Thus, our study does not produce eccentricity excitation on a timescale of a
few Myr -- we obtain either eccentricity excitation on a short time scale, or
eccentricity damping on a longer time scale. Finally, we discuss the
implications of this result for producing the observed range in extrasolar
planet eccentricity.",0708.0335v1
2007-10-10,HE 0515-4414 - an unusual sub-damped Ly alpha system revisited,"Using STIS and VLT UVES observations we have examined the ionization,
abundances, and differential dust depletion of metals, the kinematic structure,
and the physical conditions in the molecular hydrogen-bearing sub-damped Ly
alpha system toward HE 0515-4414 at z = 1.15. The velocity interval of
associated metal lines extends for 700 km/s. In addition, saturated H I
absorption is detected in the blue damping wing of the main component. The
column density ratios of associated Al II, Al III, and Fe II lines indicate
that the absorbing material is ionized. 19 of in total 31 detected metal line
components are formed within peripheral H II regions, while only 12 components
are associated with the predominantly neutral main absorber. For the main
absorber the observed abundance ratios of refractory elements to Zn range from
Galactic warm disk [Si/Zn] = - 0.40, [Fe/Zn] = -1.10 to halo-like and
essentially undepleted patterns. The dust-corrected metal abundances indicate a
nucleosynthetic odd-even effect and might imply an anomalous depletion of Si
relative to Fe for two components, but otherwise do correspond to solar ratios.
The intrinsic average metallicity is almost solar [Fe/H] = -0.08, whereas the
uncorrected average is [Zn/H] = -0.38. The ion abundances in the periphery
conform with solar element composition. The detection of H II as well as the
large variation in dust depletion for this sight line raises the question
whether in future studies of damped Ly alpha systems ionization and depletion
effects have to be considered in further detail. Ionization effects, for
instance, may pretend an enrichment of alpha elements. An empirical recipe for
detecting H II regions is provided.",0710.3560v1
2008-06-05,Viscous damping of r-mode oscillations in compact stars with quark matter,"We determine characteristic timescales for the viscous damping of r-mode
oscillations in rapidly rotating compact stars that contain quark matter. We
present results for the color-flavor-locked (CFL) phase of dense quark matter,
in which the up, down and strange quarks are gapped, as well as the normal
(ungapped) quark phase. While the ungapped quark phase supports a temperature
window between 10^8 K and 5x10^9 K where the r-mode is damped even for rapid
rotation, the r-mode in a rapidly rotating pure CFL star is not damped in the
temperature range 10^10 K - 10^11 K. Rotating hybrid stars with quark matter
cores display an instability window whose width is determined by the amount of
quark matter present, and they can have large spin frequencies outside this
window. Except at high temperatures T > 10^10 K, the presence of a quark phase
allows for larger critical frequencies and smaller spin-periods compared to
rotating neutron stars. If low-mass X-ray binaries contain a large amount of
ungapped or CFL quark matter, then our estimates of the r-mode instability
suggest that there should be a population of rapidly rotating binaries at
frequencies greater than 1000 Hz which have not yet been observed.",0806.1005v2
2008-06-09,Relaxation Time and Relaxation Function of Quark-Gluon Plasma with Lattice QCD,"We propose a method which enables a QCD-based calculation of a relaxation
time for a dissipative current in the causal and dissipative hydrodynamic
equation derived by Israel and Stewart. We point out that the Israel-Stewart
equation is not unique as a causal and dissipative hydrodynamic equation, and
the form of the causal and dissipative hydrodynamic equation is determined by
the shape of a spectral function reflecting the properties of elementary
excitations in the system we consider. Our method utilizes a relaxation
function, which can be calculated from QCD using the linear response theory. We
show that the relaxation function can be derived from a spectral function for a
microscopic representation of the dissipative current. We also show that the
Israel-Stewart equation is acceptable only as long as the calculated relaxation
function is approximated well by a exponentially damping function, and the
relaxation time can be obtained as its damping time constant. Taking a
baryon-number dissipative current of a plasma consisting of charm quarks and
gluons as a simple example, we present the first calculation of the relaxation
function with use of the spectral function derived employing the quenched
lattice QCD together with the maximum entropy method. The calculated relaxation
function shows a strongly-oscillation damping behaviour due to the charmed
vector hadron $J/\Psi$ surviving above the deconfinement phase transition
temperature in QCD. This result suggests that the applicability of the
Israel-Stewart equation to the baryon-number dissipative current of the charm
quark-gluon plasma is quite doubtful. We present an idea for the improvement of
the Israel-Stewart equation by deriving the hydrodynamic equation consistent
with the strongly-oscillation damping relaxation function.",0806.1481v1
2008-06-18,Imaging method for interface rheological characterization,"The present work investigates free damped oscillations of an oil drop in
water after its release from a capillary tube. Both pure heptane drops and
diluted crude oil drops are considered (in the second case the interface is
covered by amphiphilic species, natural components of crude oil). Shadowgraph
images of the drops are taken by means of a high speed camera and the drop
contour is detected by image processing. The axisymmetric drop shape is then
decomposed into spherical harmonics, which constitute the eigenmodes of
oscillations predicted by the Rayleigh-Lamb theory. Time evolution of each mode
is then obtained. The frequency and the damping rate of the principal mode
(n=2) are accurately determined and compared with theoretical values for an
immobile clean drop oscillating around spherical shape. For pure heptane drops,
theoretical value of the frequency agrees well with experiments whereas the
damping rate is significantly underestimated by theory. The experimental
results clearly show that the different modes are coupled. Energy is thus
transfered from mode n=2 to n=3, which probably explains the observed
enhancement of the damping rate. The effect of the interface viscoelastic
behaviour, induced by adsorbed amphiphilic species on the free oscillations was
examined. No significant effect was observed in the experiments conditions
(small amplitude oscillations and moderate aging).",0806.3030v1
2008-06-27,Klein - Gordon equation for market wealth operations,"In this paper the modified Klein - Gordon equation for market processes is
proposed and solved. It is argued that the oscillations in market propagate
with the light velocity. The initial pulse in the market is damped and for very
large time diffused according to the Fourier law.",0806.4466v1
2008-10-22,"Mean Motion Resonances in Extrasolar Planetary Systems with Turbulence, Interactions, and Damping","This paper continues previous work on the effects of turbulence on mean
motion resonances in extrasolar planetary systems. Turbulence is expected to
arise in the disks that form planets, and these fluctuations act to compromise
resonant configurations. This paper extends previous work by considering how
interactions between the planets and possible damping effects imposed by the
disk affect the outcomes. These physical processes are studied using three
approaches: numerical integrations of the 3-body problem with additional
forcing due to turbulence, model equations that reduce the problem to
stochastically driven oscillators, and Fokker-Planck equations that describe
the time evolution of an ensemble of systems. With this combined approach, we
elucidate the physics of how turbulence can remove extrasolar planetary systems
from mean motion resonance. As expected, systems with sufficiently large
damping (dissipation) can maintain resonance, in spite of turbulent forcing. In
the absence of strong damping, ensembles of these systems exhibit two regimes
of behavior, where the fraction of the bound states decreases as a power-law or
as an exponential. Both types of behavior can be understood through the model
developed herein. For systems with weak interactions between planets, the model
reduces to a stochastic pendulum, and the fraction of bound states decreases as
a power-law. For highly interactive systems, the dynamics are more complicated
and the fraction of bound states decreases exponentially. We show how planetary
interactions lead to drift terms in the Fokker-Planck equation and account for
this exponential behavior. In addition to clarifying the physical processes
involved, this paper strengthens the finding that turbulence implies that mean
motions resonances should be rare.",0810.4076v1
2009-01-11,On the derivation of structural models with general thermomechanical prestress,"The vibrating behaviour of thin structures is affected by prestress states.
Hence, the effects of thermal prestress are important research subjects in view
of ambient vibration monitoring of civil structures. The interaction between
prestress, geometrically non-linear behaviour, as well as damping and its
coupling with the aforementioned phenomena has to be taken into account for a
comprehensive understanding of the structural behaviour. Since the literature
on this subject lacks a clear procedure to derive models of thin prestressed
and damped structures from 3D continuum mechanics, this paper presents a new
derivation of models for thin structures accounting for generic prestress,
moderate rotations and viscous damping. Although inspired by classical
approaches, the proposed procedure is quite different, because of (i) the
definition of a modified Hu-Washizu (H-W) functional, accounting for stress
constraints associated with Lagrange multipliers, in order to derive
lower-dimensional models in a convenient way; (ii) an original definition of a
(mechanical and thermal) strain measure and a rotation measure enabling one to
identify the main terms in the strain energy and to derive a cascade of
lower-dimensional models (iii) a new definition of ""strain-rotation domains""
providing a clear interpretation of the classical assumptions of ""small
perturbations"" and ""small strains and moderate rotations""; (iv) the
introduction of a pseudo-potential with stress constraints to account for
viscous damping. The proposed procedure is applied to thin beams.",0901.1446v1
2009-04-17,On Landau damping,"Going beyond the linearized study has been a longstanding problem in the
theory of Landau damping. In this paper we establish exponential Landau damping
in analytic regularity. The damping phenomenon is reinterpreted in terms of
transfer of regularity between kinetic and spatial variables, rather than
exchanges of energy; phase mixing is the driving mechanism. The analysis
involves new families of analytic norms, measuring regularity by comparison
with solutions of the free transport equation; new functional inequalities; a
control of nonlinear echoes; sharp scattering estimates; and a Newton
approximation scheme. Our results hold for any potential no more singular than
Coulomb or Newton interaction; the limit cases are included with specific
technical effort. As a side result, the stability of homogeneous equilibria of
the nonlinear Vlasov equation is established under sharp assumptions. We point
out the strong analogy with the KAM theory, and discuss physical implications.",0904.2760v5
2009-07-27,Parameter exploration of optically trapped liquid aerosols,"When studying the motion of optically trapped particles on the $\mu s$ time
scale, in low viscous media such as air, inertia cannot be neglected.
Resolution of unusual and interesting behaviour not seen in colloidal trapping
experiments is possible. In attempt to explain the phenomena we use power
spectral methods to perform a parameter study of the Brownian motion of
optically trapped liquid aerosol droplets concentrated around the critically
damped regime. We present evidence that the system is suitably described by a
simple harmonic oscillator model which must include a description of
Fax\'{e}n's correction, but not necessarily frequency dependent hydrodynamic
corrections to Stokes' law. We also provide results describing how the system
behaves under several variables and discuss the difficulty in decoupling the
parameters responsible for the observed behaviour. We show that due to the
relatively low dynamic viscosity and high trap stiffness it is easy to transfer
between over- and under-damped motion by experimentally altering either trap
stiffness or damping. Our results suggest stable aerosol trapping may be
achieved in under-damped conditions, but the onset of deleterious optical
forces at high trapping powers prevents the probing of the upper stability
limits due to Brownian motion.",0907.4582v2
2009-10-09,One-way coupled Van der Pol system,"The equation of the Van der Pol oscillator, being characterized by a
dissipative term, is non-Lagrangian. Appending an additional degree of freedom
we bring the equation in the frame of action principle and thus introduce a
one-way coupled system. As with the Van der Pol oscillator, the coupled system
also involves only one parameter that controls the dynamics. The response
system is described by a linear differential equation coupled nonlinearly to
the drive system. In the linear approximation the equations of our coupled
system coincide with those of the Bateman dual system (a pair of damped and
anti-damped harmonic oscillators). The critical point of damped and anti-damped
oscillators are stable and unstable for all physical values of the frictional
coefficient $\mu$. Contrarily, the critical points of the drive- (Van der Pol)
and response systems depend crucially on the values of $\mu$. These points are
unstable for $\mu > 0$ while the critical point of the drive system is stable
and that of the response system is unstable for $\mu < 0$. The one-way coupled
system exhibits bifurcations which are different from those of the uncoupled
Van der Pol oscillator. Our system is chaotic and we observe phase
synchronization in the regime of dynamic chaos only for small values of $\mu$.",0910.1700v1
2010-02-17,Measurement of Gilbert damping parameters in nanoscale CPP-GMR spin-valves,"In-situ, device level measurement of thermal mag-noise spectral linewidths in
60nm diameter CPP-GMR spin-valve stacks of IrMn/ref/Cu/free, with reference and
free layer of similar CoFe/CoFeGe alloy, are used to simultaneously determine
the intrinsic Gilbert damping for both magnetic layers. It is shown that
careful alignment at a ""magic-angle"" between free and reference layer static
equilibrium magnetization can allow direct measurement of the broadband
intrinsic thermal spectra in the virtual absence of spin-torque effects which
otherwise grossly distort the spectral line shapes and require linewidth
extrapolations to zero current (which are nonetheless also shown to agree well
with the direct method). The experimental magic-angle spectra are shown to be
in good qualitative and quantitative agreement with both macrospin calculations
and micromagnetic eigenmode analysis. Despite similar composition and
thickness, it is repeatedly found that the IrMn exchange pinned reference layer
has ten times larger intrinsic Gilbert damping (alpha ~ 0.1) than that of the
free-layer (alpha ~ 0.01). It is argued that the large reference layer damping
results from strong, off -resonant coupling to to lossy modes of an IrMn/ref
couple, rather than commonly invoked two-magnon processes.",1002.3295v1
2010-06-19,On the saturation amplitude of the f-mode instability,"We investigate strong nonlinear damping effects which occur during high
amplitude oscillations of neutron stars, and the gravitational waves they
produce. For this, we use a general relativistic nonlinear hydrodynamics code
in conjunction with a fixed spacetime (Cowling approximation) and a polytropic
equation of state (EOS). Gravitational waves are estimated using the quadrupole
formula. Our main interest are l=m=2 f modes subject to the CFS (Chandrasekhar,
Friedman, Schutz) instability, but we also investigate axisymmetric and
quasiradial modes. We study various models to determine the influence of
rotation rate and EOS. We find that axisymmetric oscillations at high
amplitudes are predominantly damped by shock formation, while the
nonaxisymmetric f modes are mainly damped by wave breaking and, for rapidly
rotating models, coupling to nonaxisymmetric inertial modes. From the observed
nonlinear damping, we derive upper limits for the saturation amplitude of
CFS-unstable f modes. Finally, we estimate that the corresponding gravitational
waves for an oscillation amplitude at the upper limit should be detectable with
the advanced LIGO and VIRGO interferometers at distances above 10 MPc. This
strongly depends on the stellar model, in particular on the mode frequency.",1006.3885v2
2010-07-06,Magneto-elastic oscillations and the damping of crustal shear modes in magnetars,"In a realistic model of magneto-elastic oscillations in magnetars, we find
that crustal shear oscillations, often invoked as an explanation of
quasi-periodic oscillations (QPOs) seen after giant flares in soft gamma-ray
repeaters (SGRs), are damped by resonant absorption on timescales of at most
0.2s, for a lower limit on the dipole magnetic field strength of 5 x 10^13 G.
At higher magnetic field strengths (typical in magnetars) the damping timescale
is even shorter, as anticipated by earlier toy-models. We have investigated a
range of equations of state and masses and if magnetars are dominated by a
dipole magnetic field, our findings exclude torsional shear oscillations of the
crust from explaining the observed low-frequency QPOs. In contrast, we find
that the Alfv\'en QPO model is a viable explanation of observed QPOs, if the
dipole magnetic field strength exceeds a minimum strength of about several
times 10^14 G to 10^15 G. Then, Alfv\'en QPOs are no longer confined to the
fluid core, but completely dominate in the crust region and have a maximum
amplitude at the surface of the star.",1007.0856v2
2010-08-16,Orbital evolution of eccentric planets in radiative discs,"With an average eccentricity of about 0.29, the eccentricity distribution of
extrasolar planets is markedly different from the solar system. Among other
scenarios considered, it has been proposed that eccentricity may grow through
planet-disc interaction. Recently, it has been noticed that the thermodynamical
state of the disc can significantly influence the migration properties of
growing protoplanets. However, the evolution of planetary eccentricity in
radiative discs has not been considered yet. In this paper we study the
evolution of planets on eccentric orbits that are embedded in a
three-dimensional viscous disc and analyse the disc's effect on the orbital
evolution of the planet. We use the three-dimensional hydrodynamical code
NIRVANA that includes full tensor viscosity and implicit radiation transport in
the flux-limited diffusion approximation. The code uses the FARGO-algorithm to
speed up the simulations. First we measure the torque and power exerted on the
planet by the disc for fixed orbits, and then we let the planet start with
initial eccentricity and evolve it in the disc. For locally isothermal we
confirm previous results and find eccentricity damping and inward migration for
planetary cores. In the case of radiative discs, the planets experience an
inward migration as long as its eccentricity lies above a certain threshold.
After the damping of eccentricity cores with masses below 33 Earthmasses begin
to migrate outward in radiative discs, while higher mass cores always migrate
inward. For all planetary masses studied (up to 200 Earthmasses) we find
eccentricity damping. In viscous discs the orbital eccentricity of embedded
planets is damped during the evolution independent of the mass. Hence,
planet-disc interaction does not seem to be a viable mechanism to explain the
observed high eccentricity of exoplanets.",1008.2656v1
2010-11-02,A Carbon-enhanced Metal-poor Damped Lyman alpha System: Probing Gas from Population III Nucleosynthesis?,"We present high resolution observations of an extremely metal-poor damped
Lyman-alpha system, at z_abs = 2.3400972 in the spectrum of the QSO J0035-0918,
exhibiting an abundance pattern consistent with model predictions for the
supernova yields of Population III stars. Specifically, this DLA has [Fe/H] =
-3.04, shows a clear `odd-even' effect, and is C-rich with [C/Fe] = +1.53, a
factor of about 20 greater than reported in any other damped Lyman-alpha
system. In analogy to the carbon-enhanced metal-poor stars in the Galactic halo
(with [C/Fe] > +1.0), this is the first reported case of a carbon-enhanced
damped Lyman-alpha system. We determine an upper limit to the mass of 12C,
M(12C) < 200 solar masses, which depends on the unknown gas density n(H); if
n(H) > 1 atom per cubic cm (which is quite likely for this DLA given its low
velocity dispersion), then M(12C) < 2 solar masses, consistent with pollution
by only a few prior supernovae. We speculate that DLAs such as the one reported
here may represent the `missing link' between the yields of Pop III stars and
their later incorporation in the class of carbon-enhanced metal-poor stars
which show no enhancement of neutron-capture elements (CEMP-no stars).",1011.0733v2
2010-11-08,Exponential stabilization without geometric control,"We present examples of exponential stabilization for the damped wave equation
on a compact manifold in situations where the geometric control condition is
not satisfied. This follows from a dynamical argument involving a topological
pressure on a suitable uncontrolled set.",1011.1699v1
2010-11-11,Damping of longitudinal magneto-acoustic oscillations in slowly varying coronal plasma,"We investigate the propagation of MHD waves in a homogenous, magnetized
plasma in a weakly stratified atmosphere, representing hot coronal loops. In
most of earlier studies a time-independent equilibrium is considered. Here we
abandon this restriction and allow the equilibrium to develop as function of
time. In particular, the background plasma is assumed to be cooling due to
thermal conduction. The cooling is assumed to be on a time scale greater than
the characteristic travel times of the perturbations. We investigate the
influence of cooling of the background plasma on the properties of
magneto-acoustic waves. The MHD equations are reduced to a 1-D system modelling
magneto-acoustic modes progressing along a dynamically cooling coronal loop. A
time dependent dispersion relation which describes the propagation of the
magneto-acoustic waves is derived by using the WKB theory. An analytic solution
for the time-dependent amplitude of waves is obtained and the method of
characteristics is used to find an approximate analytical solution. Numerical
calculations are applied to the analytically derived solutions to obtain
further insight into the behavior of the MHD waves in a system with variable,
time-dependent background. The results show that there is a strong damping of
MHD waves that can be linked to the widely observed damping of hot coronal loop
oscillations. The damping also appears to be independent of position along the
loop. Studies of MHD wave behaviour in time-dependent background seem to be a
fundamental and very important next step in developing MHD wave theory
applicable to a wide range in solar physics.",1011.2617v1
2010-12-17,Optimal switching of a nanomagnet assisted by microwaves,"We develop an efficient and general method for optimizing the microwave field
that achieves magnetization switching with a smaller static field. This method
is based on optimal control and renders an exact solution for the 3D microwave
field that triggers the switching of a nanomagnet with a given anisotropy and
in an oblique static field. Applying this technique to the particular case of
uniaxial anisotropy, we show that the optimal microwave field, that achieves
switching with minimal absorbed energy, is modulated both in frequency and in
magnitude. Its role is to drive the magnetization from the metastable
equilibrium position towards the saddle point and then damping induces the
relaxation to the stable equilibrium position. For the pumping to be efficient,
the microwave field frequency must match at the early stage of the switching
process the proper precession frequency of the magnetization, which depends on
the magnitude and direction of the static field. We investigate the effect of
the static field (in amplitude and direction) and of damping on the
characteristics of the microwave field. We have computed the switching curves
in the presence of the optimal microwave field. The results are in qualitative
agreement with micro-SQUID experiments on isolated nanoclusters. The strong
dependence of the microwave field and that of the switching curve on the
damping parameter may be useful in probing damping in various nanoclusters.",1012.3901v1
2010-12-22,PageRank for ranking authors in co-citation networks,"Google's PageRank has created a new synergy to information retrieval for a
better ranking of Web pages. It ranks documents depending on the topology of
the graphs and the weights of the nodes. PageRank has significantly advanced
the field of information retrieval and keeps Google ahead of competitors in the
search engine market. It has been deployed in bibliometrics to evaluate
research impact, yet few of these studies focus on the important impact of the
damping factor (d) for ranking purposes. This paper studies how varied damping
factors in the PageRank algorithm can provide additional insight into the
ranking of authors in an author co-citation network. Furthermore, we propose
weighted PageRank algorithms. We select 108 most highly cited authors in the
information retrieval (IR) area from the 1970s to 2008 to form the author
co-citation network. We calculate the ranks of these 108 authors based on
PageRank with damping factor ranging from 0.05 to 0.95. In order to test the
relationship between these different measures, we compare PageRank and weighted
PageRank results with the citation ranking, h-index, and centrality measures.
We found that in our author co-citation network, citation rank is highly
correlated with PageRank's with different damping factors and also with
different PageRank algorithms; citation rank and PageRank are not significantly
correlated with centrality measures; and h-index is not significantly
correlated with centrality measures.",1012.4872v1
2011-01-20,Magnetohydrodynamic waves in solar partially ionized plasmas: two-fluid approach,"We derive the dynamics of magnetohydrodynamic waves in two-fluid partially
ionized plasmas and to compare the results with those obtained under
single-fluid description. Two-fluid magnetohydrodynamic equations are used,
where ion-electron plasma and neutral particles are considered as separate
fluids. Dispersion relations of linear magnetohydrodynamic waves are derived
for simplest case of homogeneous medium. Frequencies and damping rates of waves
are obtained for different parameters of background plasma. We found that two-
and single-fluid descriptions give similar results for low frequency waves.
However, the dynamics of MHD waves in two-fluid approach is significantly
changed when the wave frequency becomes comparable or higher than ion-neutral
collision frequency. Alfven and fast magneto-acoustic waves attain their
maximum damping rate at particular frequencies (for example, the peak frequency
equals 2.5 ion-neutral collision frequency for 50 % of neutral Hydrogen) in
wave spectrum. The damping rates are reduced for higher frequency waves. The
new mode of slow magneto-acoustic wave appears for higher frequency branch,
which is connected to neutral hydrogen fluid. The single-fluid approach
perfectly deals with slow processes in partially ionized plasmas, but fails for
time-scales smaller than ion-neutral collision time. Therefore, two-fluid
approximation should be used for the description of relatively fast processes.
Some results of single-fluid description, for example the damping of
high-frequency Alfven waves in the solar chromosphere due to ion-neutral
collisions, should be revised in future.",1101.3913v1
2011-08-25,Characterizing Multi-planet Systems with Classical Secular Theory,"Classical secular theory can be a powerful tool to describe the qualitative
character of multi-planet systems and offer insight into their histories. The
eigenmodes of the secular behavior, rather than current orbital elements, can
help identify tidal effects, early planet-planet scattering, and dynamical
coupling among the planets, for systems in which mean-motion resonances do not
play a role. Although tidal damping can result in aligned major axes after all
but one eigenmode have damped away, such alignment may simply be fortuitous. An
example of this is 55 Cancri (orbital solution of Fischer et al., 2008) where
multiple eigenmodes remain undamped. Various solutions for 55 Cancri are
compared, showing differing dynamical groupings, with implications for the
coupling of eccentricities and for the partitioning of damping among the
planets. Solutions for orbits that include expectations of past tidal evolution
with observational data, must take into account which eigenmodes should be
damped, rather than expecting particular eccentricities to be near zero.
Classical secular theory is only accurate for low eccentricity values, but
comparison with other results suggests that it can yield useful qualitative
descriptions of behavior even for moderately large eccentricity values, and may
have advantages for revealing underlying physical processes and, as large
numbers of new systems are discovered, for triage to identify where more
comprehensive dynamical studies should have priority.",1108.5149v2
2011-09-12,Nonlinear spectroscopy of superconducting anharmonic resonators,"We formulate a model for the steady state response of a nonlinear quantum
oscillator structure, such as those used in a variety of superconducting qubit
experiments, when excited by a steady, but not necessarily small, ac tone. We
show that this model can be derived directly from a circuit description of some
recent qubit experiments in which the state of the qubit is read out directly,
without a SQUID magnetometer. The excitation profile has a rich structure
depending on the detuning of the tone from the small-signal resonant frequency,
on the degree of damping, and on the excitation amplitude. We explore two
regions in detail: First, at high damping there is a trough in the excitation
response as a function of detuning, near where the classical Duffing
bifurcation occurs. This trough has been understood as a classical interference
between two metastable responses with opposite phase. We use Wigner function
studies to show that while this picture is roughly correct, there are also more
quantum mechanical aspects to this feature. Second, at low damping we study the
emergence of sharp, discrete spectral features from a continuum response. We
show that these the structures, associated with discrete transitions between
different excited-state eigenstates of the oscillator, provide an interesting
example of a quantum Fano resonance. The trough in the Fano response evolves
continuously from the ""classical"" trough at high damping.",1109.2490v1
2012-06-15,"Comment on ""Anisotropic Critical Magnetic Fluctuations in the Ferromagnetic Superconductor UCoGe""","We have presented the potential explanation of nonvanishing at q=0 Landau
damping measured experimentally in ferromagnetic compounds UGe2 and UCoGe based
on possible intersection of the Fermi sheets corresponding different bands.",1206.3468v1
2012-06-21,Interaction between an Isotropic Nanoparticle and Drifting Electrons in a Quantum Well,"A hybrid system composed of an isotropic nanoparticle and a semiconductor
heterostructure with a quantum well has been considered. The nanoparticle is
supposed to be polarizable in an external electric field. A theoretical model
of the hybrid system is substantiated and formulated. Exact solutions of the
model equations are obtained. The frequencies of charge oscillations in the
hybrid system and their damping owing to the dipole--plasmon interaction are
found, the damping mechanism being similar to that of Landau damping. The
space-time behavior of concentration perturbations in the two-dimensional
electron gas is analyzed, and the polarization oscillations of a nanoparticle
are studied. The induced polarization of a nanoparticle at nonzero electron
drift velocities is found to have a complicated dynamics. In particular, the
polarization vector circulates along elliptic trajectories for two of three
frequency dispersion branches. If the electric current flows through the
quantum well due to an applied electric field, the damping of oscillations in
the hybrid system is replaced by their growth in time, which corresponds to the
electric instability of the system. New phenomena in hybrid systems can be used
to excite the emission of nanoparticles by an electric current and to
electrically stimulate the emission in the terahertz spectral range.",1206.4782v1
2012-10-02,Coherence and Stimulated Emission in the Tavis-Cummings Model: A Quantum Description of the Free Induction Signal and Radiation Damping in Magnetic Resonance,"We numerically solve the Liouville equation for the Tavis Cummings model of
multiple spins coupled to a lossless single mode cavity, starting from an
initial condition with small numbers of fully polarized spins tipped by a
specified angle, and the cavity in its ground Fock state. Time evolution of the
magnetizations and cavity states, following small to medium nutation by a
classical field, yields a microscopic quantum mechanical picture of radiation
damping in magnetic resonance, and the formation of the free induction signal,
that is, the transfer of Zeeman energy, via spin coherence, to cavity
coherence. Although the motion of the Bloch vector is nonclassical, our quantum
description is related to the macroscopic picture of NMR reception, by showing
the close relationship between the usual radiation damping constant, and the
quantum mechanical Rabi nutation frequency (as enhanced by cavity coupling and
stimulated emission.) That is, each is the product, of a nutation rate per
oscillator current, and a current. Although the current in the damping constant
is explicitly limited by cavity losses, which do not enter the formula for the
Rabi frequency, we nonetheless show (in an appendix) how these losses can be
introduced into our problem by means of a master equation. Numerical solution
of the classical Bloch-Kirchhoff equations reinforces the conclusion that the
strength of the free induction",1210.0868v2
2012-10-11,Experimental estimations of viscoelastic properties of multilayer damped plates in broad-band frequency range,"Regarding lightweighting structures for aeronautics, automotive or
construction applications, the level of performance of solutions proposed in
terms of damping and isolation is fundamental. Hence multilayered plate appears
as an interesting answer if damping performances are properly optimized. In
this paper, a novel modal analysis method (Ege et al, JSV 325 (4-5), 2009) is
used to identify viscoelastic properties (loss factors, Young's modulus) of
""polyethylene thermoplastic / aluminum"" bilayer plates. The thermoplastic is
chosen for its high loss factors and relative low mass. The experimental method
consists in a high-resolution technique (ESPRIT algorithm) which allows precise
estimations of the viscoelastic properties even in frequency domains with high
modal overlap (high damping or modal density). Experimental loss factors
estimated from impact hammer excitations on the free-free plates highly
corresponds with two theoretical estimations. In the first model (Guyader &
Lesueur, JSV 58(1), 1978) the calculation is based on multilayered plates
equations and use wave propagation analysis ; in the second one (Laulagnet &
Guyader, JASA 96(1), 1994) the thickness deformation solving Navier's equations
is allowed. Results on several plates with several thicknesses of
thermoplastics are given and compared with the models, demonstrating the
validity of the approach.",1210.3333v3
2012-11-02,Damping of mechanical vibrations by free electrons in metallic nanoresonators,"We investigate the effect of free electrons on the quality factor (Q) of a
metallic nanomechanical resonator in the form of a thin elastic beam. The
flexural and longitudinal modes of the beam are modeled using thin beam
elasticity theory, and simple perturbation theory is used to calculate the rate
at which an externally excited vibration mode decays due to its interaction
with free electrons. We find that electron-phonon interaction significantly
affects the Q of longitudinal modes, and may also be of significance to the
damping of flexural modes in otherwise high-Q beams. The finite geometry of the
beam is manifested in two important ways. Its finite length breaks translation
invariance along the beam and introduces an imperfect momentum conservation law
in place of the exact law. Its finite width imposes a quantization of the
electronic states that introduces a temperature scale for which there exists a
crossover from a high-temperature macroscopic regime, where electron-phonon
damping behaves as if the electrons were in the bulk, to a low-temperature
mesoscopic regime, where damping is dominated by just a few dissipation
channels and exhibits sharp non-monotonic changes as parameters are varied.
This suggests a novel scheme for probing the electronic spectrum of a nanoscale
device by measuring the Q of its mechanical vibrations.",1211.0450v1
2013-01-14,Two-qubit mixed states more entangled than pure states: Comparison of the relative entropy of entanglement for a given nonlocality,"Amplitude damping changes entangled pure states into usually less-entangled
mixed states. We show, however, that even local amplitude damping of one or two
qubits can result in mixed states more entangled than pure states if one
compares the relative entropy of entanglement (REE) for a given degree of the
Bell-Clauser-Horne-Shimony-Holt inequality violation (referred to as
nonlocality). By applying Monte-Carlo simulations, we find the maximally
entangled mixed states and show that they are likely to be optimal by checking
the Karush-Kuhn-Tucker conditions, which generalize the method of Lagrange
multipliers for this nonlinear optimization problem. We show that the REE for
mixed states can exceed that of pure states if the nonlocality is in the range
(0,0.82) and the maximal difference between these REEs is 0.4. A former
comparison [Phys. Rev. A 78, 052308 (2008)] of the REE for a given negativity
showed analogous property but the corresponding maximal difference in the REEs
is one-order smaller (i.e., 0.039) and the negativity range is (0,0.53) only.
For appropriate comparison, we normalized the nonlocality measure to be equal
to the standard entanglement measures, including the negativity, for arbitrary
two-qubit pure states. We also analyze the influence of the phase-damping
channel on the entanglement of the initially pure states. We show that the
minimum of the REE for a given nonlocality can be achieved by this channel,
contrary to the amplitude damping channel.",1301.2969v2
2013-07-02,The ESO UVES Advanced Data Products Quasar Sample - I. Dataset and New N_HI Measurements of Damped Absorbers,"We present here a dataset of quasars observed with the Ultraviolet Visual
Echelle Spectrograph (UVES) on the VLT and available in the ESO UVES Advanced
Data Products archive. The sample is made up of a total of 250 high resolution
quasar spectra with emission redshifts ranging from 0.191 < z_em <6.311. The
total UVES exposure time of this dataset is 1560 hours. Thanks to the high
resolution of UVES spectra, it is possible to unambiguously measure the column
density of absorbers with damping wings, down to N_HI > 10^{19} cm^{-2}, which
constitutes the sub-damped Lya absorber (sub-DLA) threshold. Within the
wavelength coverage of our UVES data, we find 150 damped Lya systems
(DLAs)/sub-DLAs in the range 1.5 < z_abs < 4.7. Of these 150, 93 are DLAs and
57 are sub-DLAs. An extensive search in the literature indicates that 6 of
these DLAs and 13 of these sub-DLAs have their N_HI measured for the first
time. Among them, 10 are new identifications as DLAs/sub-DLAs. For each of
these systems, we obtain an accurate measurement of the HI column density and
the absorber's redshift in the range 1.7 < z_abs < 4.2 by implementing a Voigt
profile-fitting algorithm. These absorbers are further confirmed thanks to the
detection of associated metal lines and/or lines from members of the Lyman
series. In our data, a few quasars' lines-of-sight are rich. An interesting
example is towards QSO J0133+0400 (z_em = 4.154) with six DLAs and sub-DLAs
reported.",1307.0678v2
2013-10-20,Nonequilibrium stationary state for a damped rotator,"Perturbative construction of the nonequilibrium steady state of a rotator
under a stochastic forcing while subject to torque and friction",1310.5379v1
2013-11-07,Spin-Orbit Torques and Anisotropic Magnetization Damping in Skyrmion Crystals,"The length scale of the magnetization gradients in chiral magnets is
determined by the relativistic Dzyaloshinskii-Moriya interaction. Thus, even
conventional spin-transfer torques are controlled by the relativistic
spin-orbit coupling in these systems, and additional relativistic corrections
to the current-induced torques and magnetization damping become important for a
complete understanding of the current-driven magnetization dynamics. We
theoretically study the effects of reactive and dissipative homogeneous
spin-orbit torques and anisotropic damping on the current-driven skyrmion
dynamics in cubic chiral magnets. Our results demonstrate that spin-orbit
torques play a significant role in the current-induced skyrmion velocity. The
dissipative spin-orbit torque generates a relativistic Magnus force on the
skyrmions, whereas the reactive spin-orbit torque yields a correction to both
the drift velocity along the current direction and the transverse velocity
associated with the Magnus force. The spin-orbit torque corrections to the
velocity scale linearly with the skyrmion size, which is inversely proportional
to the spin-orbit coupling. Consequently, the reactive spin-orbit torque
correction can be the same order of magnitude as the non-relativistic
contribution. More importantly, the dissipative spin-orbit torque can be the
dominant force that causes a deflected motion of the skyrmions if the torque
exhibits a linear or quadratic relationship with the spin-orbit coupling. In
addition, we demonstrate that the skyrmion velocity is determined by
anisotropic magnetization damping parameters governed by the skyrmion size.",1311.1778v1
2013-11-13,Recent progress in attractors for quintic wave equations,"We report on new results concerning the global well-posedness, dissipativity
and attractors of the damped quintic wave equations in bounded domains of R^3.",1311.3290v1
2014-01-19,Analytical Solution of Mathieu Equation,"The general solution of the homogeneous damped Mathieu equation in the
analytical form, allowing its practical using in many applications, including
superconductivity studies, without numerical calculations has been found.",1401.5348v1
2014-10-15,A comparison of weak-turbulence and PIC simulations of weak electron-beam plasma interaction,"Quasilinear theory has long been used to treat the problem of a weak electron
beam interacting with plasma and generating Langmuir waves. Its extension to
weak-turbulence theory treats resonant interactions of these Langmuir waves
with other plasma wave modes, in particular ion-sound waves. These are strongly
damped in plasma of equal ion and electron temperatures, as sometimes seen in,
for example, the solar corona and wind. Weak turbulence theory is derived in
the weak damping limit, with a term describing ion-sound wave damping then
added. In this paper we use the EPOCH particle-in-cell code to numerically test
weak turbulence theory for a range of electron-ion temperature ratios. We find
that in the cold ion limit the results agree well, but increasing ion
temperature the three-wave resonance becomes broadened in proportion to the
ion-sound wave damping rate. This may be important in, for example, the theory
of solar radio bursts, where the spectrum of Langmuir waves is critical.
Additionally we establish lower limits on the number of simulation particles
needed to accurately reproduce the electron and wave distributions in their
saturated states, and to reproduce their intermediate states and time
evolution.",1410.4046v2
2015-03-31,Existence of the global attractor for the plate equation with nonlocal nonlinearity in R^{n},"We consider Cauchy problem for the semilinear plate equation with nonlocal
nonlinearity. Under mild conditions on the damping coefficient, we prove that
the semigroup generated by this problem possesses a global attractor.",1503.09123v1
2015-05-07,Theory for Bose-Einstein condensation of light in nano-fabricated semiconductor microcavities,"We construct a theory for Bose-Einstein condensation of light in
nano-fabricated semiconductor microcavities. We model the semiconductor by one
conduction and one valence band which consist of electrons and holes that
interact via a Coulomb interaction. Moreover, we incorporate screening effects
by using a contact interaction with the scattering length for a Yukawa
potential and describe in this manner the crossover from exciton gas to
electron-hole plasma as we increase the excitation level of the semiconductor.
We then show that the dynamics of the light in the microcavities is damped due
to the coupling to the semiconductor. Furthermore, we demonstrate that on the
electron-hole plasma side of the crossover, which is relevant for the
Bose-Einstein condensation of light, this damping can be described by a single
dimensionless damping parameter that depends on the external pumping.
Hereafter, we propose to probe the superfluidity of light in these
nano-fabricated semiconductor microcavities by making use of the differences in
the response in the normal or superfluid phase to a sudden rotation of the
trap. In particular, we determine frequencies and damping of the scissors modes
that are excited in this manner. Moreover, we show that a distinct signature of
the dynamical Casimir effect can be observed in the density-density
correlations of the excited light fluid.",1505.01732v2
2015-08-21,Which verification qubits perform best for secure communication in noisy channel?,"In secure quantum communication protocols, a set of single qubits prepared
using 2 or more mutually unbiased bases or a set of $n$-qubit ($n\geq2$)
entangled states of a particular form are usually used to form a verification
string which is subsequently used to detect traces of eavesdropping. The qubits
that form a verification string are referred to as decoy qubits, and there
exists a large set of different quantum states that can be used as decoy
qubits. In the absence of noise, any choice of decoy qubits provides equivalent
security. In this paper, we examine such equivalence for noisy environment
(e.g., in amplitude damping, phase damping, collective dephasing and collective
rotation noise channels) by comparing the decoy-qubit assisted schemes of
secure quantum communication that use single qubit states as decoy qubits with
the schemes that use entangled states as decoy qubits. Our study reveals that
the single qubit assisted scheme perform better in some noisy environments,
while some entangled qubits assisted schemes perform better in other noisy
environments. Specifically, single qubits assisted schemes perform better in
amplitude damping and phase damping noisy channels, whereas a few
Bell-state-based decoy schemes are found to perform better in the presence of
the collective noise. Thus, if the kind of noise present in a communication
channel (i.e., the characteristics of the channel) is known or measured, then
the present study can provide the best choice of decoy qubits required for
implementation of schemes of secure quantum communication through that channel.",1508.05237v1
2015-08-30,Spin-transfer torque based damping control of parametrically excited spin waves in a magnetic insulator,"The damping of spin waves parametrically excited in the magnetic insulator
Yttrium Iron Garnet (YIG) is controlled by a dc current passed through an
adjacent normal-metal film. The experiment is performed on a macroscopically
sized YIG(100nm)/Pt(10nm) bilayer of 4x2 mm^2 lateral dimensions. The spin-wave
relaxation frequency is determined via the threshold of the parametric
instability measured by Brillouin light scattering (BLS) spectroscopy. The
application of a dc current to the Pt film leads to the formation of a
spin-polarized electron current normal to the film plane due to the spin Hall
effect (SHE). This spin current exerts a spin transfer torque (STT) in the YIG
film and, thus, changes the spin-wave damping. Depending on the polarity of the
applied dc current with respect to the magnetization direction, the damping can
be increased or decreased. The magnitude of its variation is proportional to
the applied current. A variation in the relaxation frequency of +/-7.5% is
achieved for an applied dc current density of 5*10^10 A/m^2.",1508.07517v1
2015-09-08,Model comparison for the density structure across solar coronal waveguides,"The spatial variation of physical quantities, such as the mass density,
across solar atmospheric waveguides governs the timescales and spatial scales
for wave damping and energy dissipation. The direct measurement of the spatial
distribution of density, however, is difficult and indirect seismology
inversion methods have been suggested as an alternative. We applied Bayesian
inference, model comparison, and model-averaging techniques to the inference of
the cross-field density structuring in solar magnetic waveguides using
information on periods and damping times for resonantly damped
magnetohydrodynamic (MHD) transverse kink oscillations. Three commonly employed
alternative profiles were used to model the variation of the mass density
across the waveguide boundary. Parameter inference enabled us to obtain
information on physical quantities such as the Alfv\'en travel time, the
density contrast, and the transverse inhomogeneity length scale. The inference
results from alternative density models were compared and their differences
quantified. Then, the relative plausibility of the considered models was
assessed by performing model comparison. Our results indicate that the evidence
in favor of any of the three models is minimal, unless the oscillations are
strongly damped. In such a circumstance, the application of model-averaging
techniques enables the computation of an evidence-weighted inference that takes
into account the plausibility of each model in the calculation of a combined
inversion for the unknown physical parameters.",1509.02340v1
2015-09-15,Resonance vibration of impact oscillator with biharmonic excitation,"We consider a damped impact oscillator subject to the action of a biharmonic
force. The conditions for the existence and stability of almost periodic
resonance solutions are investigated.",1509.05381v1
2015-11-08,On 2d incompressible Euler equations with partial damping,"We consider various questions about the 2d incompressible Navier-Stokes and
Euler equations on a torus when dissipation is removed from or added to some of
the Fourier modes.",1511.02530v1
2016-01-26,Fast convex optimization via inertial dynamics with Hessian driven damping,"We first study the fast minimization properties of the trajectories of the
second-order evolution equation $$\ddot{x}(t) + \frac{\alpha}{t} \dot{x}(t) +
\beta \nabla^2 \Phi (x(t))\dot{x} (t) + \nabla \Phi (x(t)) = 0,$$ where
$\Phi:\mathcal H\to\mathbb R$ is a smooth convex function acting on a real
Hilbert space $\mathcal H$, and $\alpha$, $\beta$ are positive parameters. This
inertial system combines an isotropic viscous damping which vanishes
asymptotically, and a geometrical Hessian driven damping, which makes it
naturally related to Newton's and Levenberg-Marquardt methods. For $\alpha\geq
3$, $\beta >0$, along any trajectory, fast convergence of the values
$$\Phi(x(t))- \min_{\mathcal H}\Phi =\mathcal O\left(t^{-2}\right)$$ is
obtained, together with rapid convergence of the gradients $\nabla\Phi(x(t))$
to zero. For $\alpha>3$, just assuming that $\Phi$ has minimizers, we show that
any trajectory converges weakly to a minimizer of $\Phi$, and $
\Phi(x(t))-\min_{\mathcal H}\Phi = o(t^{-2})$. Strong convergence is
established in various practical situations. For the strongly convex case,
convergence can be arbitrarily fast depending on the choice of $\alpha$. More
precisely, we have $\Phi(x(t))- \min_{\mathcal H}\Phi = \mathcal
O(t^{-\frac{2}{3}\alpha})$. We extend the results to the case of a general
proper lower-semicontinuous convex function $\Phi : \mathcal H \rightarrow
\mathbb R \cup \{+\infty \}$. This is based on the fact that the inertial
dynamic with Hessian driven damping can be written as a first-order system in
time and space. By explicit-implicit time discretization, this opens a gate to
new $-$ possibly more rapid $-$ inertial algorithms, expanding the field of
FISTA methods for convex structured optimization problems.",1601.07113v1
2016-03-28,Stabilization of gravity water waves,"This paper is devoted to the stabilization of the incompressible Euler
equation with free surface. We study the damping of two-dimensional gravity
waves by an absorbing beach where the water-wave energy is dissipated by using
the variations of the external pressure.",1603.08541v1
2016-06-14,Precession Relaxation of Viscoelastic Oblate Rotators,"Perturbations of all sorts destabilise the rotation of a small body and leave
it in a non-principal spin state. In such a state, the body experiences
alternating stresses generated by the inertial forces. This yields nutation
relaxation, i.e., evolution of the spin towards the principal rotation about
the maximal-inertia axis. Knowledge of the timescales needed to damp the
nutation is crucial in studies of small bodies' dynamics. In the literature
hitherto, nutation relaxation has always been described with aid of an
empirical quality factor $\,Q\,$ introduced to parameterise the energy
dissipation rate.
  Among the drawbacks of this approach was its inability to describe the
dependence of the relaxation rate upon the current nutation angle. This
inability stemmed from our lack of knowledge of the quality factor's dependence
on the forcing frequency. In this article, we derive our description of
nutation damping directly from the rheological law obeyed by the material. This
renders us the nutation damping rate as a function of the current nutation
angle, as well as of the shape and the rheological parameters of the body. In
contradistinction from the approach based on an empirical $\,Q\,$-factor, our
development gives a zero damping rate in the spherical-shape limit. Our method
is generic and applicable to any shape and to any linear rheological law.
However, to simplify the developments, here we consider a dynamically oblate
rotator with a Maxwell rheology.",1606.04559v3
2016-09-07,Quasi-stability and Exponential Attractors for A Non-Gradient System---Applications to Piston-Theoretic Plates with Internal Damping,"We consider a nonlinear (Berger or Von Karman) clamped plate model with a
{\em piston-theoretic} right hand side---which include non-dissipative,
non-conservative lower order terms. The model arises in aeroelasticity when a
panel is immersed in a high velocity linear potential flow; in this case the
effect of the flow can be captured by a dynamic pressure term written in terms
of the material derivative of the plate's displacement. The effect of
fully-supported internal damping is studied for both Berger and von Karman
dynamics. The non-dissipative nature of the dynamics preclude the use of strong
tools such as backward-in-time smallness of velocities and finiteness of the
dissipation integral. Modern quasi-stability techniques are utilized to show
the existence of compact global attractors and generalized fractal exponential
attractors. Specific results depending on the size of the damping parameter and
the nonlinearity in force. For the Berger plate, in the presence of large
damping, the existence of a proper global attractor (whose fractal dimension is
finite in the state space) is shown via a decomposition of the nonlinear
dynamics. This leads to the construction of a compact set upon which
quasi-stability theory can be implemented. Numerical investigations for
appropriate 1-D models are presented which explore and support the abstract
results presented herein.",1609.02211v1
2016-10-26,On the region of attraction of phase-locked states for swing equations on connected graphs with inhomogeneous dampings,"We consider the synchronization problem of swing equations, a second-order
Kuramoto-type model, on connected networks with inhomogeneous dampings. This
was largely motivated by its relevance to the dynamics of power grids. We focus
on the estimate of the region of attraction of synchronous states which is a
central problem in the transient stability of power grids. In the recent
literature, D\""{o}rfler, Chertkov, and Bullo [Proc. Natl. Acad. Sci. USA, 110
(2013), pp. 2005-2010] found a condition for the synchronization in smart
grids. They pointed out that the region of attraction is an important unsolved
problem. In [SIAM J. Control Optim., 52 (2014), pp. 2482-2511], only a special
case was considered where the oscillators have homogeneous dampings and the
underlying graph has a diameter less than or equal to 2. There the analysis
heavily relies on these assumptions; however, they are too strict compared to
the real power networks. In this paper, we continue the study and derive an
estimate on the region of attraction of phase-locked states for lossless power
grids on connected graphs with inhomogeneous dampings. Our main strategy is
based on the gradient-like formulation and energy estimate. We refine the
assumptions by constructing a new energy functional which enables us to
consider such general settings.",1610.08437v1
2016-10-31,A quest for new physics inside the neutron,"The lecture presents an overview of the quest for the new physics in low
energy neutron phenomena. In addition to the traditional topics the quantum
damping of $n$ $\bar{n}$ oscillations is discussed.",1610.10046v1
2017-02-27,Current Induced Damping of Nanosized Quantum Moments in the Presence of Spin-Orbit Interaction,"Motivated by the need to understand current-induced magnetization dynamics at
the nanoscale, we have developed a formalism, within the framework of Keldysh
Green function approach, to study the current-induced dynamics of a
ferromagnetic (FM) nanoisland overlayer on a spin-orbit-coupling (SOC) Rashba
plane. In contrast to the commonly employed classical micromagnetic LLG
simulations the magnetic moments of the FM are treated {\it quantum
mechanically}. We obtain the density matrix of the whole system consisting of
conduction electrons entangled with the local magnetic moments and calculate
the effective damping rate of the FM. We investigate two opposite limiting
regimes of FM dynamics: (1) The precessional regime where the magnetic
anisotropy energy (MAE) and precessional frequency are smaller than the
exchange interactions, and (2) The local spin-flip regime where the MAE and
precessional frequency are comparable to the exchange interactions. In the
former case, we show that due to the finite size of the FM domain, the
\textquotedblleft Gilbert damping\textquotedblright does not diverge in the
ballistic electron transport regime, in sharp contrast to Kambersky's breathing
Fermi surface theory for damping in metallic FMs. In the latter case, we show
that above a critical bias the excited conduction electrons can switch the
local spin moments resulting in demagnetization and reversal of the
magnetization. Furthermore, our calculations show that the bias-induced
antidamping efficiency in the local spin-flip regime is much higher than that
in the rotational excitation regime.",1702.08408v2
2017-03-21,Evidence for structural damping in a high-stress silicon nitride nanobeam and its implications for quantum optomechanics,"We resolve the thermal motion of a high-stress silicon nitride nanobeam at
frequencies far below its fundamental flexural resonance (3.4 MHz) using
cavity-enhanced optical interferometry. Over two decades, the displacement
spectrum is well-modeled by that of a damped harmonic oscillator driven by a
$1/f$ thermal force, suggesting that the loss angle of the beam material is
frequency-independent. The inferred loss angle at 3.4 MHz, $\phi = 4.5\cdot
10^{-6}$, agrees well with the quality factor ($Q$) of the fundamental beam
mode ($\phi = Q^{-1}$). In conjunction with $Q$ measurements made on higher
order flexural modes, and accounting for the mode dependence of stress-induced
loss dilution, we find that the intrinsic (undiluted) loss angle of the beam
changes by less than a factor of 2 between 50 kHz and 50 MHz. We discuss the
impact of such ""structural damping"" on experiments in quantum optomechanics, in
which the thermal force acting on a mechanical oscillator coupled to an optical
cavity is overwhelmed by radiation pressure shot noise. As an illustration, we
show that structural damping reduces the bandwidth of ponderomotive squeezing.",1703.07134v2
2017-03-29,"Comment on ""Spreading widths of giant resonances in spherical nuclei: damped transient response"" by Severyukhin et al. [arXiv:1703.05710]","We argue whether physics of universal approach of Severyukhin et al.
[arXiv:1703.05710] is approved.",1703.10003v1
2017-08-16,The Frequency-dependent Damping of Slow Magnetoacoustic Waves in a Sunspot Umbral Atmosphere,"High spatial and temporal resolution images of a sunspot, obtained
simultaneously in multiple optical and UV wavelengths, are employed to study
the propagation and damping characteristics of slow magnetoacoustic waves up to
transition region heights. Power spectra are generated from intensity
oscillations in sunspot umbra, across multiple atmospheric heights, for
frequencies up to a few hundred mHz. It is observed that the power spectra
display a power-law dependence over the entire frequency range, with a
significant enhancement around 5.5 mHz found for the chromospheric channels.
The phase-difference spectra reveal a cutoff frequency near 3 mHz, up to which
the oscillations are evanescent, while those with higher frequencies propagate
upwards. The power-law index appears to increase with atmospheric height. Also,
shorter damping lengths are observed for oscillations with higher frequencies
suggesting frequency-dependent damping. Using the relative amplitudes of the
5.5 mHz (3 minute) oscillations, we estimate the energy flux at different
heights, which seems to decay gradually from the photosphere, in agreement with
recent numerical simulations. Furthermore, a comparison of power spectra across
the umbral radius highlights an enhancement of high-frequency waves near the
umbral center, which does not seem to be related to magnetic field inclination
angle effects.",1708.04835v1
2017-08-29,Spin wave damping arising from phase coexistence below $T_c$ in colossal magnetoresistive La$_{0.7}$Ca$_{0.3}$MnO$_3$,"While the spin dynamics of La$_{0.7}$Ca$_{0.3}$MnO$_3$ in the ferromagnetic
phase are known to be unconventional, previous measurements have yielded
contradictory results regarding the damping of spin wave excitations. Neutron
spectroscopy measurements on a sample with a transition temperature of
$T_c$=257 K, higher than most single crystals, unambiguously reveal an
anomalous increase in spin wave damping for excitations approaching the
Brillouin zone boundary along the [$100$] direction that cannot be explained as
an artifact due to a noninteracting phonon branch. Spin waves throughout the
($HK0$) plane display a common trend where the spin wave damping is dependent
upon the excitation energy, increasing for energies above roughly 15 meV and
reaching a full width at half maximum of at least 20 meV. The results are
consistent with a model of intrinsic spatial inhomogeneity with phase separated
regions approximately 18 {\AA} in size persisting over a large range of
temperatures below $T_c$.",1708.08960v2
2018-02-18,On energy stable discontinuous Galerkin spectral element approximations of the perfectly matched layer for the wave equation,"We develop a provably energy stable discontinuous Galerkin spectral element
method (DGSEM) approximation of the perfectly matched layer (PML) for the three
and two space dimensional (3D and 2D) linear acoustic wave equations, in first
order form, subject to well-posed linear boundary conditions. First, using the
well-known complex coordinate stretching, we derive an efficient un-split modal
PML for the 3D acoustic wave equation. Second, we prove asymptotic stability of
the continuous PML by deriving energy estimates in the Laplace space, for the
3D PML in a heterogeneous acoustic medium, assuming piece-wise constant PML
damping. Third, we develop a DGSEM for the wave equation using physically
motivated numerical flux, with penalty weights, which are compatible with all
well-posed, internal and external, boundary conditions. When the PML damping
vanishes, by construction, our choice of penalty parameters yield an upwind
scheme and a discrete energy estimate analogous to the continuous energy
estimate. Fourth, to ensure numerical stability when PML damping is present, it
is necessary to systematically extend the numerical numerical fluxes, and the
inter-element and boundary procedures, to the PML auxiliary differential
equations. This is critical for deriving discrete energy estimates analogous to
the continuous energy estimates. Finally, we propose a procedure to compute PML
damping coefficients such that the PML error converges to zero, at the optimal
convergence rate of the underlying numerical method. Numerical experiments are
presented in 2D and 3D corroborating the theoretical results.",1802.06388v1
2018-11-15,Damping rate of a fermion in ultradegenerate chiral matter,"We compute the damping rate of a fermion propagating in a chiral plasma when
there is an imbalance between the densities of left- and right-handed fermions,
after generalizing the hard thermal loop resummation techniques for these
systems. In the ultradegenerate limit, for very high energies the damping rate
of this external fermion approaches a constant value. Closer to the two Fermi
surfaces, however, we find that the rate depends on both the energy and the
chirality of the fermion, being higher for the predominant chirality. This
comes out as a result of its scattering with the particles of the plasma,
mediated by the exchange of Landau damped photons. In particular, we find that
the chiral imbalance is responsible for a different propagation of the left and
right circular polarised transverse modes of the photon, and that a chiral
fermion interacts differently with these two transverse modes. We argue that
spontaneous radiation of energetic fermions is kinematically forbidden, and
discuss the time regime where our computation is valid.",1811.06394v3
2019-05-04,A class of second-order geometric quasilinear hyperbolic PDEs and their application in imaging science,"In this paper, we study damped second-order dynamics, which are quasilinear
hyperbolic partial differential equations (PDEs). This is inspired by the
recent development of second-order damping systems for accelerating energy
decay of gradient flows. We concentrate on two equations: one is a damped
second-order total variation flow, which is primarily motivated by the
application of image denoising; the other is a damped second-order mean
curvature flow for level sets of scalar functions, which is related to a
non-convex variational model capable of correcting displacement errors in image
data (e.g. dejittering). For the former equation, we prove the existence and
uniqueness of the solution. For the latter, we draw a connection between the
equation and some second-order geometric PDEs evolving the hypersurfaces which
are described by level sets of scalar functions, and show the existence and
uniqueness of the solution for a regularized version of the equation. The
latter is used in our algorithmic development. A general algorithm for
numerical discretization of the two nonlinear PDEs is proposed and analyzed.
Its efficiency is demonstrated by various numerical examples, where simulations
on the behavior of solutions of the new equations and comparisons with
first-order flows are also documented.",1905.01457v2
2020-07-19,Global existence and convergence to the modified Barenblatt solution for the compressible Euler equations with physical vacuum and time-dependent damping,"In this paper, the smooth solution of the physical vacuum problem for the one
dimensional compressible Euler equations with time-dependent damping is
considered. Near the vacuum boundary, the sound speed is $C^{1/2}$-H\""{o}lder
continuous. The coefficient of the damping depends on time, given by this form
$\frac{\mu}{(1+t)^\lambda}$, $\lambda$, $\mu>0$, which decays by order
$-\lambda$ in time. Under the assumption that $0<\lambda<1$, $0<\mu$ or
$\lambda=1$, $2<\mu$, we will prove the global existence of smooth solutions
and convergence to the modified Barenblatt solution of the related porous media
equation with time-dependent dissipation and the same total mass when the
initial data of the Euler equations is a small perturbation of that of the
Barenblatt solution. The pointwise convergence rates of the density, velocity
and the expanding rate of the physical vacuum boundary are also given. The
proof is based on space-time weighted energy estimates, elliptic estimates and
Hardy inequality in the Lagrangian coordinates. Our result is an extension of
that in Luo-Zeng [Comm. Pure Appl. Math. 69 (2016), no. 7, 1354-1396], where
the authors considered the physical vacuum free boundary problem of the
compressible Euler equations with constant-coefficient damping.",2007.14802v2
2013-08-23,Stabilization of second-order evolution equations with time delay,"We consider second-order evolution equations in an abstract setting with
damping and time delay and give sufficient conditions ensuring exponential
stability. Our abstract framework is then applied to the wave equation, the
elasticity system and the Petrovsky system.",1308.5106v1
2016-11-28,First Demonstration of Electrostatic Damping of Parametric Instability at Advanced LIGO,"Interferometric gravitational wave detectors operate with high optical power
in their arms in order to achieve high shot-noise limited strain sensitivity. A
significant limitation to increasing the optical power is the phenomenon of
three-mode parametric instabilities, in which the laser field in the arm
cavities is scattered into higher order optical modes by acoustic modes of the
cavity mirrors. The optical modes can further drive the acoustic modes via
radiation pressure, potentially producing an exponential buildup. One proposed
technique to stabilize parametric instability is active damping of acoustic
modes. We report here the first demonstration of damping a parametrically
unstable mode using active feedback forces on the cavity mirror. A 15,538 Hz
mode that grew exponentially with a time constant of 182 sec was damped using
electro-static actuation, with a resulting decay time constant of 23 sec. An
average control force of 0.03 nNrms was required to maintain the acoustic mode
at its minimum amplitude.",1611.08997v1
2011-11-09,Stabilization by switching control methods,"In this paper we consider some stabilization problems for the wave equation
with switching. We prove exponential stability results for appropriate damping
coefficients. The proof of the main results is based on D'Alembert formula and
some energy estimates.",1111.2171v1
2012-04-09,The Kato Smoothing Effect for Regularized Schrödinger Equations in Exterior Domains,"We prove, under the exterior geometric control condition, the Kato smoothing
effect for solutions of an inhomogenous and damped Schr\""odinger equation on
exterior domains.",1204.1904v1
2012-04-26,Well-posedness and long time behavior in nonlinear dissipative hyperbolic-like evolutions with critical exponents,"These lectures present the analysis of stability and control of long time
behavior of PDE models described by nonlinear evolutions of hyperbolic type.
Specific examples of the models under consideration include: (i) nonlinear
systems of dynamic elasticity: von Karman systems, Berger's equations,
Kirchhoff - Boussinesq equations, nonlinear waves (ii) nonlinear flow -
structure and fluid - structure interactions, (iii) and nonlinear
thermo-elasticity. A characteristic feature of the models under consideration
is criticality or super-criticality of sources (with respect to Sobolev's
embeddings) along with super-criticality of damping mechanisms which, in
addition, may be also geometrically constrained.
  Our aim is to present several methods relying on cancelations, harmonic
analysis and geometric analysis, which enable to handle criticality and also
super-criticality in both sources and the damping of the underlined nonlinear
PDE. It turns out that if carefully analyzed the nonlinearity can be taken
""advantage of"" in order to produce implementable damping mechanism.
  Another goal of these lectures is the understanding of control mechanisms
which are geometrically constrained. The final task boils down to showing that
appropriately damped system is ""quasi-stable"" in the sense that any two
trajectories approach each other exponentially fast up to a compact term which
can grow in time. Showing this property- formulated as quasi-stability estimate
-is the key and technically demanding issue that requires suitable tools. These
include: weighted energy inequalities, compensated compactness, Carleman's
estimates and some elements of microlocal analysis.",1204.5864v1
2013-09-21,Bottomonium suppression at $\sqrt{s_{NN}}=2.76$ TeV using model based on color screening and gluonic dissociation with collisional damping,"We present a model to explain the bottomonium suppression in Pb+Pb collisions
at mid rapidity obtained from Large Hadron Collider (LHC) energy,
$\sqrt{s_{NN}}=2.76$ TeV. The model consists of two decoupled mechanisms
namely, color screening during bottomonium production followed by gluon induced
dissociation along with collisional damping. The quasi-particle model (QPM) is
used as equation of state (EOS) for the Quark-Gluon Plasma (QGP) medium. The
feed-down from higher $\Upsilon$ states, such as $\Upsilon(1P)$, $\Upsilon(2S)$
and $\Upsilon(2P)$, dilated formation times for bottomonium states and viscous
effect of QGP medium are other ingredients included in the current formulation.
We further assume that the QGP is expanding according to (1+1)-dimensional
Bjorken's boost invariant scaling law. The net suppression (in terms of $p_T$
integrated survival probability) for bottomonium states at mid rapidity is
obtained as a function of centrality and the result is then compared both
quantitatively and qualitatively with the recent LHC experimental data in the
mid rapidity region recently published by CMS collaboration. We find that the
current model, based on the Debye color screening plus gluonic dissociation
along with collisional damping, better describes the centrality dependence of
bottomonium suppression at LHC energy as compared to color screening model
alone.
  \vskip 0.5cm
  {\nd \it Keywords} : Color screening, Gluonic dissociation, Collisional
damping, Survival probability {\nd \it PACS numbers} : 12.38.Mh, 12.38.Gc,
25.75.Nq, 24.10.Pa",1309.5467v2
2014-06-11,Quantum critical metals in $4-ε$ dimensions,"We study the quantum theory of a Fermi surface coupled to a gapless boson
scalar in $D=4-\epsilon$ spacetime dimensions as a simple model for non-Fermi
liquids (NFL) near a quantum phase transition. Our analysis takes into account
the full backreaction from Landau damping of the boson, and obtains an RG flow
that proceeds through three distinct stages. Above the scale of Landau damping
the Fermi velocity flows to zero, while the coupling evolves according to its
classical dimension. Once damping becomes important, its backreaction leads to
a crossover regime where dynamic and static damping effects compete and the
fermion self-energy does not respect scaling. Below this crossover and having
tuned the boson to criticality, the theory flows to a $z=3$ scalar interacting
with a NFL. By increasing the number of bosonic flavors, the phase diagram near
the quantum critical point interpolates between a superconducting dome fully
covering the NFL behavior, and a phase where NFL effects become important
first, before the onset of superconductivity. A generic prediction of the
theory is that the Fermi velocity and quasiparticle residue vanish with a
power-law $\omega^\epsilon$ as the fixed point is approached. These features
may be useful for understanding some of the phenomenology of high $T_c$
materials in a systematic $\epsilon$--expansion.",1406.3029v2
2015-12-11,The Ping Pong Pendulum,"Many damped mechanical systems oscillate with increasing frequency as the
amplitude decreases. One popular example is Euler's Disk, where the point of
contact rotates with increasing rapidity as the energy is dissipated. We study
a simple mechanical pendulum that exhibits this behaviour.",1512.03700v1
2016-12-19,Improving the efficiency of joint remote state preparation in noisy environment with weak measurement,"Quantum secure communication provides a new way for protecting the security
of information. As an important component of quantum secure communication,
remote state preparation (RSP) can securely transmit a quantum state from a
sender to a remote receiver. The existence of quantum noise severely affects
the security and reliability of quantum communication system. In this paper, we
study the method for improving the efficiency of joint RSP (JRSP) subjected to
noise with the help of weak measurement and its reversal measurement. Taking a
GHZ based deterministic JRSP as an example, we utilize the technique of weak
measurement and its reversal to suppress the effect of the amplitude-damping
noise firstly. Our study shows that the fidelity of the output state can be
improved in the amplitude-damping noise. We also study the effect of weak
measurement and its reversal in other three types of noise usually encountered
in real-world, namely, the bit-flip, phase-flip (phase-damping) and
depolarizing noise. Our results show that the weak measurement has no effect
for suppressing the bit-flip and phase-flip (phase-damping) noise, while has
slight effect for suppressing the depolarizing noise. Our study is suitable for
JRSP and RSP, and will be helpful for improving the efficiency of multiparticle
entanglement based quantum secure communication in real implementation.",1612.06020v1
2017-10-11,Collisional damping rates for plasma waves,"The distinction between the plasma dynamics dominated by collisional
transport versus collective processes has never been rigorously addressed until
recently. A recent paper [Yoon et al., Phys. Rev. E 93, 033203 (2016)]
formulates for the first time, a unified kinetic theory in which collective
processes and collisional dynamics are systematically incorporated from first
principles. One of the outcomes of such a formalism is the rigorous derivation
of collisional damping rates for Langmuir and ion-acoustic waves, which can be
contrasted to the heuristic customary approach. However, the results are given
only in formal mathematical expressions. The present Brief Communication
numerically evaluates the rigorous collisional damping rates by considering the
case of plasma particles with Maxwellian velocity distribution function so as
to assess the consequence of the rigorous formalism in a quantitative manner.
Comparison with the heuristic (""Spitzer"") formula shows that the accurate
damping rates are much lower in magnitude than the conventional expression,
which implies that the traditional approach over-estimates the importance of
attenuation of plasma waves by collisional relaxation process. Such a finding
may have a wide applicability ranging from laboratory to space and
astrophysical plasmas.",1710.03874v1
2017-11-30,"Implications of dark matter cascade decay from DAMPE, HESS, Fermi-LAT and AMS02 data","Recent high-energy cosmic $e^\pm$ measurement from the DArk Matter Particle
Explorer (DAMPE) satellite confirms the deviation of total cosmic ray electron
spectrum above 700-900 GeV from a simple power law. In this paper we
demonstrate that the cascade decay of dark matter (DM) can account for DAMPE's
TeV $e^+e^-$ spectrum. We select the least constraint DM decay channel into
four muons as the benchmark scenario, and perform an analysis with propagation
variance in both DM signal and the Milky Way's electron background. The
best-fit of the model is obtained for joint DAMPE, Fermi-Large Area Telescope
(Fermi-LAT), High Energy Stereoscopic System (HESS), high energy electron data
sets, and with an $\mathcal{O}(10^{26})$ second decay lifetime, which is
consistent with existing gamma ray and cosmic microwave background limits. We
compare the spectral difference between the cascade decay of typical
final-state channels. The least constrained $4\mu$ channels give good fits to
the electron spectrum's TeV scale down-turn, yet their low energy spectrum has
tension with sub-TeV positron data from AMS02. We also consider a three-step
cascade decay into eight muons, and also a gamma-ray constrained $4\mu,4b$
mixed channel, to demonstrate that a further softened cascade decay signal
would be required for the agreement with all the data sets.",1712.00370v3
2017-12-04,"Scalar dark matter, Type II Seesaw and the DAMPE cosmic ray $e^+ + e^-$ excess","The DArk Matter Particle Explorer (DAMPE) has reported a measurement of the
flux of high energy cosmic ray electrons plus positrons (CREs) in the energy
range between $25$ GeV and $4.6$ TeV. With unprecedented high energy
resolution, the DAMPE data exhibit an excess of the CREs flux at an energy of
around $1.4$ TeV. In this letter, we discuss how the observed excess can be
understood in a minimal framework where the Standard Model (SM) is supplemented
by a stable SM singlet scalar as dark matter (DM) and type II seesaw for
generating the neutrino mass matrix. In our framework, a pair of DM particles
annihilates into a pair of the SM SU(2) triplet scalars ($\Delta$s) in type II
seesaw, and the subsequent $\Delta$ decays create the primary source of the
excessive CREs around $1.4$ TeV. The lepton flavor structure of the primary
source of CREs has a direct relationship with the neutrino oscillation data. We
find that the DM interpretation of the DAMPE excess determines the pattern of
neutrino mass spectrum to be the inverted hierarchy type, taking into account
the constraints from the Fermi-LAT observations of dwarf spheroidal galaxies.",1712.00869v2
2017-12-07,Nonlinear growth of structure in cosmologies with damped matter fluctuations,"We investigate the nonlinear evolution of structure in variants of the
standard cosmological model which display damped density fluctuations relative
to cold dark matter (e.g. in which cold dark matter is replaced by warm or
interacting DM). Using N-body simulations, we address the question of how much
information is retained from different scales in the initial linear power
spectrum following the nonlinear growth of structure. We run a suite of N-body
simulations with different initial linear matter power spectra to show that,
once the system undergoes nonlinear evolution, the shape of the linear power
spectrum at high wavenumbers does not affect the non-linear power spectrum,
while it still matters for the halo mass function. Indeed, we find that linear
power spectra which differ from one another only at wavenumbers larger than
their half-mode wavenumber give rise to (almost) identical nonlinear power
spectra at late times, regardless of the fact that they originate from
different models with damped fluctuations. On the other hand, the halo mass
function is more sensitive to the form of the linear power spectrum. Exploiting
this result, we propose a two parameter model of the transfer function in
generic damped scenarios, and show that this parametrisation works as well as
the standard three parameter models for the scales on which the linear spectrum
is relevant.",1712.02742v2
2017-12-11,DAMPE excess from decaying right-handed neutrino dark matter,"The flux of high-energy cosmic-ray electrons plus positrons recently measured
by the DArk Matter Particle Explorer (DAMPE) exhibits a tentative peak excess
at an energy of around $1.4$ TeV. In this paper, we consider the minimal gauged
$U(1)_{B-L}$ model with a right-handed neutrino (RHN) dark matter (DM) and
interpret the DAMPE peak with a late-time decay of the RHN DM into $e^\pm
W^\mp$. We find that a DM lifetime $\tau_{DM} \sim 10^{28}$ s can fit the DAMPE
peak with a DM mass $m_{DM}=3$ TeV. This favored lifetime is close to the
current bound on it by Fermi-LAT, our decaying RHN DM can be tested once the
measurement of cosmic gamma ray flux is improved. The RHN DM communicates with
the Standard Model particles through the $U(1)_{B-L}$ gauge boson ($Z^\prime$
boson), and its thermal relic abundance is controlled by only three free
parameters: $m_{DM}$, the $U(1)_{B-L}$ gauge coupling ($\alpha_{BL}$), and the
$Z^\prime$ boson mass ($m_{Z^\prime}$). For $m_{DM}=3$ TeV, the rest of the
parameters are restricted to be $m_{Z^\prime}\simeq 6$ TeV and $0.00807 \leq
\alpha_{BL} \leq 0.0149$, in order to reproduce the observed DM relic density
and to avoid the Landau pole for the running $\alpha_{BL}$ below the Planck
scale. This allowed region will be tested by the search for a $Z^\prime$ boson
resonance at the future Large Hadron Collider.",1712.03652v3
2017-12-11,A Statistical Study on The Frequency-Dependent Damping of Slow-mode Waves in Polar Plumes and Interplumes,"We perform a statistical study on the frequency-dependent damping of slow
waves propagating along polar plumes and interplumes in the solar corona.
Analysis of a large sample of extreme ultraviolet (EUV) imaging data with high
spatial and temporal resolutions obtained from AIA/SDO suggests an inverse
power-law dependence of the damping length on the periodicity of slow waves
(i.e., the shorter period oscillations exhibit longer damping lengths), in
agreement with the previous case studies. Similar behavior is observed in both
plume and interplume regions studied in AIA 171 \AA\ and AIA 193 \AA\
passbands. It is found that the short-period (2--6 min) waves are relatively
more abundant than their long period (7--30 min) counterparts in contrast to
the general belief that the polar regions are dominated by the longer-period
slow waves. We also derived the slope of the power spectra ($\mathrm{\alpha}$,
the power-law index) statistically to better understand the characteristics of
turbulence present in the region. It is found that the $\mathrm{\alpha}$ values
and their distributions are similar in both plume and interplume structures
across the two AIA passbands. At the same time, the spread of these
distributions also indicates the complexity of the underlying turbulence
mechanism.",1712.03673v1
2018-09-19,Critical exponent for the semilinear wave equations with a damping increasing in the far field,"We consider the Cauchy problem of the semilinear wave equation with a damping
term \begin{align*}
  u_{tt} - \Delta u + c(t,x) u_t = |u|^p, \quad (t,x)\in (0,\infty)\times
\mathbb{R}^N,\quad
  u(0,x) = \varepsilon u_0(x), \ u_t(0,x) = \varepsilon u_1(x), \quad x\in
\mathbb{R}^N, \end{align*} where $p>1$ and the coefficient of the damping term
has the form \begin{align*}
  c(t,x) = a_0 (1+|x|^2)^{-\alpha/2} (1+t)^{-\beta} \end{align*} with some $a_0
> 0$, $\alpha < 0$, $\beta \in (-1, 1]$. In particular, we mainly consider the
cases $ \alpha < 0, \beta =0$ or $\alpha < 0, \beta = 1$, which imply $\alpha +
\beta < 1$, namely, the damping is spatially increasing and effective. Our aim
is to prove that the critical exponent is given by $ p = 1+
\frac{2}{N-\alpha}$. This shows that the critical exponent is the same as that
of the corresponding parabolic equation $c(t,x) v_t - \Delta v = |v|^p$. The
global existence part is proved by a weighted energy estimates with an
exponential-type weight function and a special case of the
Caffarelli-Kohn-Nirenberg inequality. The blow-up part is proved by a
test-function method introduced by Ikeda and Sobajima (arXiv:1710.06780v1). We
also give an upper estimate of the lifespan.",1809.06994v1
2018-09-28,Isotropic non-local Gilbert damping driven by spin currents in epitaxial Pd/Fe/MgO(001) films,"Although both theoretical predications and experimental observations
demonstrated that the damping factor is anisotropic at
ferromagnet/semiconductor interface with robust interfacial spin-orbit
coupling, it is not well understood whether non-local Gilbert damping driven by
spin currents in heavy metal/ferromagnetic metal (HM/FM) bilayers is
anisotropic or not. Here, we investigated the in-plane angular- and frequency-
dependence of magnetic relaxation of epitaxial Fe/MgO(001) films with different
capping layers of Pd and Cu. After disentangling the parasitic contributions,
such as two-magnon scattering (TMS), mosaicity, and field-dragging effect, we
unambiguously observed that both local and non-local Gilbert damping are
isotropic in Fe(001) plane, suggesting that the pure spin currents absorption
is independent of Fe magnetization orientation in the epitaxial Pd/Fe
heterostructure. First principles calculation reveals that the effective spin
mixing conductance of Pd/Fe interface is nearly invariant for different
magnetization directions in good agreement with the experimental observations.
These results offer a valuable insight into the transmission and absorption of
pure spin currents, and facilitate us to utilize next-generation spintronic
devices.",1809.11020v1
2018-10-16,Dark matter gets DAMPE,"The DArk Matter Particle Explorer (DAMPE) recently reported an excess of
electrons/positrons above expected background fluxes even when a double
power-law background spectrum is assumed. Several dark matter models that
involve TeV-scale leptophilic WIMPs have been suggested in the literature to
account for this excess. All of these models are associated with the presence
of a nearby dark matter clump/over-density.
  In this work we set out to explore how current constraints from observational
data impact the suggested parameter space for a dark matter explanation of the
DAMPE excess, as well as make projections of the capacity of LOFAR and the
up-coming SKA to observe indirect radio emissions from the nearby dark matter
over-density.
  We show that LOFAR is incapable of probing the parameter space for DAMPE
excess models, unless the dark matter clump is in the form of an ultra-compact
mini halo. Fermi-LAT limits on dark matter annihilation are unable to probe
these models in all cases. Limits derived from diffuse Coma cluster radio
emission can probe a substantial portion of the parameter space and muon
neutrino limits inferred from galactic centre gamma-ray fluxes heavily restrict
muon coupling for the proposed WIMPs. The SKA is shown to able to fully probe
the parameter space of all the studied models using indirect emissions from the
local dark matter over-density.",1810.07176v2
2019-07-08,Single-spectrum prediction of kurtosis of water waves in a non-conservative model,"We study statistical properties after a sudden episode of wind for water
waves propagating in one direction. A wave with random initial conditions is
propagated using a forced-damped higher order Nonlinear Schr\""odinger equation
(NLS). During the wind episode, the wave action increases, the spectrum
broadens, the spectral mean shifts up and the Benjamin-Feir index (BFI) and the
kurtosis increase. Conversely, after the wind episode, the opposite occurs for
each quantity. The kurtosis of the wave height distribution is considered the
main parameter that can indicate whether rogue waves are likely to occur in a
sea state, and the BFI is often mentioned as a means to predict the kurtosis.
However, we find that while there is indeed a quadratic relation between these
two, this relationship is dependent on the details of the forcing and damping.
Instead, a simple and robust quadratic relation does exist between the kurtosis
and the bandwidth. This could allow for a single-spectrum assessment of the
likelihood of rogue waves in a given sea state. In addition, as the kurtosis
depends strongly on the damping and forcing coefficients, by combining the
bandwidth measurement with the damping coefficient, the evolution of the
kurtosis after the wind episode can be predicted.",1907.03490v1
2019-10-24,Frequency criteria for exponential stability,"We discuss some frequency-domain criteria for the exponential stability of
nonlinear feedback systems based on dissipativity theory. Applications are
given to convergence rates for certain perturbations of the damped harmonic
oscillator.",1910.10855v2
2020-01-22,Wide Area Measurement System-based Low Frequency Oscillation Damping Control through Reinforcement Learning,"Ensuring the stability of power systems is gaining more attraction today than
ever before, due to the rapid growth of uncertainties in load and renewable
energy penetration. Lately, wide area measurement system-based centralized
controlling techniques started providing a more flexible and robust control to
keep the system stable. But, such a modernization of control philosophy faces
pressing challenges due to the irregularities in delays of long-distance
communication channels and response of equipment to control actions. Therefore,
we propose an innovative approach that can revolutionize the control strategy
for damping down low frequency oscillations in transmission systems. Proposed
method is enriched with a potential of overcoming the challenges of
communication delays and other non-linearities in wide area damping control by
leveraging the capability of the reinforcement learning technique. Such a
technique has a unique characteristic to learn on diverse scenarios and
operating conditions by exploring the environment and devising an optimal
control action policy by implementing policy gradient method. Our detailed
analysis and systematically designed numerical validation prove the
feasibility, scalability and interpretability of the carefully modelled
low-frequency oscillation damping controller so that stability is ensured even
with the uncertainties of load and generation are on the rise.",2001.07829v1
2020-02-13,Semi-realistic tight-binding model for spin-orbit torques,"We compute the spin-orbit torque in a transition metal heterostructure using
Slater-Koster parameterization in the two-center tight-binding approximation
and accounting for d-orbitals only. In this method, the spin-orbit coupling is
modeled within Russel-Saunders scheme, which enables us to treat interfacial
and bulk spin-orbit transport on equal footing. The two components of the
spin-orbit torque, dissipative (damping-like) and reactive (field-like), are
computed within Kubo linear response theory. By systematically studying their
thickness and angular dependence, we were able to accurately characterize these
components beyond the traditional ""inverse spin galvanic"" and ""spin Hall""
effects. Whereas the conventional field-like torque is purely interfacial, we
unambiguously demonstrate that the conventional the damping-like torque
possesses both an interfacial and a bulk contribution. In addition, both
field-like and damping-like torques display substantial angular dependence with
strikingly different thickness behavior. While the planar contribution of the
field-like torque decreases smoothly with the nonmagnetic metal thickness, the
planar contribution of the damping-like torque increases dramatically with the
nonmagnetic metal thickness. Finally, we investigate the self-torque exerted on
the ferromagnet when the spin-orbit coupling of the nonmagnetic metal is turned
off. Our results suggest that the spin accumulation that builds up inside the
ferromagnet can be large enough to induce magnetic excitations.",2002.05533v1
2020-02-14,"One-dimensional wave equation with set-valued boundary damping: well-posedness, asymptotic stability, and decay rates","This paper is concerned with the analysis of a one dimensional wave equation
$z_{tt}-z_{xx}=0$ on $[0,1]$ with a Dirichlet condition at $x=0$ and a damping
acting at $x=1$ which takes the form $(z_t(t,1),-z_x(t,1))\in\Sigma$ for every
$t\geq 0$, where $\Sigma$ is a given subset of $\mathbb R^2$. The study is
performed within an $L^p$ functional framework, $p\in [1, +\infty]$. We aim at
determining conditions on $\Sigma$ ensuring existence and uniqueness of
solutions of that wave equation as well as strong stability and uniform global
asymptotic stability of its solutions. In the latter case, we also study the
decay rates of the solutions and their optimality. We first establish a
one-to-one correspondence between the solutions of that wave equation and the
iterated sequences of a discrete-time dynamical system in terms of which we
investigate the above mentioned issues. This enables us to provide a simple
necessary and sufficient condition on $\Sigma$ ensuring existence and
uniqueness of solutions of the wave equation as well as an efficient strategy
for determining optimal decay rates when $\Sigma$ verifies a generalized sector
condition. As an application, we solve two conjectures stated in the
literature, the first one seeking a specific optimal decay rate and the second
one associated with a saturation type of damping. In case the boundary damping
is subject to perturbations, we derive sharp results regarding asymptotic
perturbation rejection and input-to-state issues.",2002.06186v3
2020-04-24,Suppression of the longitudinal coupled bunch instability in DA$Φ$NE in collisions with a crossing angle,"In DAFNE, the Frascati $e^+e^-$ collider operating since 1998, an innovative
collision scheme, the crab waist, has been successfully implemented during the
years 2008-09. During operations for the Siddharta experiment an unusual
synchrotron oscillation damping effect induced by beam-beam collisions has been
observed. Indeed, when the longitudinal feedback is off, the positron beam
becomes unstable with currents above 200-300 mA due to coupled bunch
instability. The longitudinal instability is damped by colliding the positron
beam with a high current electron beam (of the order of 2 A). A shift of about
-600 Hz in the residual synchrotron sidebands is observed. Precise measurements
have been performed by using both a commercial spectrum analyzer and the
diagnostic capabilities of the longitudinal bunch-by-bunch feedback. The
damping effect has been observed in DAFNE for the first time during collisions
with the crab waist scheme. Our explanation, based both on theoretical
consideration and modeling simulation, is that beam collisions with a large
crossing angle produce longitudinal tune shift and spread, providing Landau
damping of synchrotron oscillations.",2004.11902v1
2020-12-04,Quantum Circuits for Collective Amplitude Damping in Two-Qubit Systems,"Quantum computers have now appeared in our society and are utilized for the
investigation of science and engineering. At present, they have been built as
intermediate-size computers containing about fifty qubits and are weak against
noise effects. Hence, they are called noisy-intermediate scale quantum devices.
In order to accomplish efficient quantum computation with using these machines,
a key issue is going to be the coherent control of individual and collective
quantum noises. In this work, we focus on a latter type and investigate
formulations of the collective quantum noises represented as quantum circuits.
To simplify our discussions and make them concrete, we analyze collective
amplitude damping processes in two-qubit systems. As verifications of our
formalisms and the quantum circuits, we demonstrate digital quantum simulations
of the collective amplitude damping by examining six different initial
conditions with varying the number of execution of an overall operation for our
quantum simulations. We observe that our results show good numerical matching
with the solution of quantum master equation for the two-qubit systems as we
increase such a number. In addition, we explain the essence of the way to
extend our formalisms to analyze the collective amplitude damping in larger
qubit systems. These results pave the way for establishing systematic
approaches to control the quantum noises and designing large-scale quantum
computers.",2012.02410v1
2020-12-10,Dimensional analysis of spring-wing systems reveals performance metrics for resonant flapping-wing flight,"Flapping-wing insects, birds, and robots are thought to offset the high power
cost of oscillatory wing motion by using elastic elements for energy storage
and return. Insects possess highly resilient elastic regions in their flight
anatomy that may enable high dynamic efficiency. However, recent experiments
highlight losses due to damping in the insect thorax that could reduce the
benefit of those elastic elements. We performed experiments on, and simulations
of a dynamically-scaled robophysical flapping model with an elastic element and
biologically-relevant structural damping to elucidate the roles of body
mechanics, aerodynamics, and actuation in spring-wing energetics. We measured
oscillatory flapping wing dynamics and energetics subject to a range of
actuation parameters, system inertia, and spring elasticity. To generalize
these results, we derive the non-dimensional spring-wing equation of motion and
present variables that describe the resonance properties of flapping systems:
$N$, a measure of the relative influence of inertia and aerodynamics, and
$\hat{K}$, the reduced stiffness. We show that internal damping scales with
$N$, revealing that dynamic efficiency monotonically decreases with increasing
$N$. Based on these results, we introduce a general framework for understanding
the roles of internal damping, aerodynamic and inertial forces, and elastic
structures within all spring-wing systems.",2012.05428v1
2021-01-22,Measurements and analysis of response function of cold atoms in optical molasses,"We report our experimental measurements and theoretical analysis of the
position response function of a cloud of cold atoms residing in the viscous
medium of an optical molasses and confined by a magneto-optical trap (MOT). We
measure the position response function by applying a transient homogeneous
magnetic field as a perturbing force. We observe a transition from a damped
oscillatory motion to an over-damped relaxation, stemming from a competition
between the viscous drag provided by the optical molasses and the restoring
force of the MOT. Our observations are in both qualitative and quantitative
agreement with the predictions of a theoretical model based on the Langevin
equation. As a consistency check, and as a prototype for future experiments, we
also study the free diffusive spreading of the atomic cloud in our optical
molasses with the confining magnetic field of the MOT turned off. We find that
the measured value of the diffusion coefficient agrees with the value predicted
by our Langevin model, using the damping coefficient. The damping coefficient
was deduced from our measurements of the position response function at the same
temperature.",2101.09118v2
2017-05-16,Propagation of transition fronts in nonlinear chains with non-degenerate on-site potentials,"We address the problem of a front propagation in chains with a bi-stable
nondegenerate on-site potential and a nonlinear gradient coupling. For a
generic nonlinear coupling, one encounters a special regime of transitions,
characterized by extremely narrow fronts, far supersonic velocities of
propagation and long waves in the oscillatory tail. This regime can be
qualitatively associated with a shock wave. The front propagation can be
described with the help of a simple reduced-order model; the latter delivers a
kinetic law, which is almost not sensitive to fine details of the on-site
potential. Besides, it is possible to predict all main characteristics of the
transition front, including its shape and frequency and amplitude of the
oscillatory tail. The numerical results are in a good agreement with the
analytical predictions. The suggested approach allows one to consider the
effects of an external pre-load and on-site damping. When the damping is
moderate, the analysis remains in the frame of the reduced-order model. It is
possible to consider the solution for the front propagating in the damped chain
as a perturbation of the undamped dynamics. This approach yield reasonable
predictions. When the damping is high, the transition front enters a completely
different asymptotic regime. The gradient nonlinearity generically turns
negligible, and the propagating front converges to the exact solution obtained
from a simple linear continuous model.",1705.05555v1
2017-09-08,Topological and Graph-coloring Conditions on the Parameter-independent Stability of Second-order Networked Systems,"In this paper, we study parameter-independent stability in qualitatively
heterogeneous passive networked systems containing damped and undamped nodes.
Given the graph topology and a set of damped nodes, we ask if output consensus
is achieved for all system parameter values. For given parameter values, an
eigenspace analysis is used to determine output consensus. The extension to
parameter-independent stability is characterized by a coloring problem, named
the richly balanced coloring (RBC) problem. The RBC problem asks if all nodes
of the graph can be colored red, blue and black in such a way that (i) every
damped node is black, (ii) every black node has blue neighbors if and only if
it has red neighbors, and (iii) not all nodes in the graph are black. Such a
colored graph is referred to as a richly balanced colored graph.
Parameter-independent stability is guaranteed if there does not exist a richly
balanced coloring. The RBC problem is shown to cover another well-known graph
coloring scheme known as zero forcing sets. That is, if the damped nodes form a
zero forcing set in the graph, then a richly balanced coloring does not exist
and thus, parameter-independent stability is guaranteed. However, the full
equivalence of zero forcing sets and parameter-independent stability holds only
true for tree graphs. For more general graphs with few fundamental cycles an
algorithm, named chord node coloring, is proposed that significantly
outperforms a brute-force search for solving the NP-complete RBC problem.",1709.02629v1
2018-08-05,"Dispersion, damping, and intensity of spin excitations in the single-layer (Bi,Pb)$_{2}$(Sr,La)$_{2}$CuO$_{6+δ}$ cuprate superconductor family","Using Cu-$L_3$ edge resonant inelastic x-ray scattering (RIXS) we measured
the dispersion and damping of spin excitations (magnons and paramagnons) in the
high-$T_\mathrm{c}$ superconductor (Bi,Pb)$_{2}$(Sr,La)$_{2}$CuO$_{6+\delta}$
(Bi2201), for a large doping range across the phase diagram ($0.03\lesssim
p\lesssim0.21$). Selected measurements with full polarization analysis
unambiguously demonstrate the spin-flip character of these excitations, even in
the overdoped sample. We find that the undamped frequencies increase slightly
with doping for all accessible momenta, while the damping grows rapidly, faster
in the (0,0)$\rightarrow$(0.5,0.5) nodal direction than in the
(0,0)$\rightarrow$(0.5,0) antinodal direction. We compare the experimental
results to numerically exact determinant quantum Monte Carlo (DQMC)
calculations that provide the spin dynamical structure factor
$S(\textbf{Q},\omega)$ of the three-band Hubbard model. The theory reproduces
well the momentum and doping dependence of the dispersions and spectral weights
of magnetic excitations. These results provide compelling evidence that
paramagnons, although increasingly damped, persist across the superconducting
dome of the cuprate phase diagram; this implies that long range
antiferromagnetic correlations are quickly washed away, while short range
magnetic interactions are little affected by doping.",1808.01682v1
2018-12-16,Nonlinear Dynamics of Spherical Shells Buckling under Step Pressure,"Dynamic buckling is addressed for complete elastic spherical shells subject
to a rapidly applied step in external pressure. Insights from the perspective
of nonlinear dynamics reveal essential mathematical features of the buckling
phenomena. To capture the strong buckling imperfection-sensitivity, initial
geometric imperfections in the form of an axisymmetric dimple at each pole are
introduced. Dynamic buckling under the step pressure is related to the
quasi-static buckling pressure. Both loadings produce catastrophic collapse of
the shell for conditions in which the pressure is prescribed. Damping plays an
important role in dynamic buckling because of the time-dependent nonlinear
interaction among modes, particularly the interaction between the spherically
symmetric 'breathing' mode and the buckling mode. In this paper we argue that
the precise frequency dependence of the damping does not matter as most of the
damping happens at a single frequency (the breathing frequency). In general,
there is not a unique step pressure threshold separating responses associated
with buckling from those that do not buckle. Instead there exists a cascade of
buckling thresholds, dependent on the damping and level of imperfection,
separating pressures for which buckling occurs from those for which it does not
occur. For shells with small and moderately small imperfections the dynamic
step buckling pressure can be substantially below the quasi-static buckling
pressure.",1812.06526v2
2018-12-18,Thermal gradient driven domain wall dynamics,"The issue of whether a thermal gradient acts like a magnetic field or an
electric current in the domain wall (DW) dynamics is investigated. Broadly
speaking, magnetization control knobs can be classified as energy-driving or
angular-momentum driving forces. DW propagation driven by a static magnetic
field is the best-known example of the former in which the DW speed is
proportional to the energy dissipation rate, and the current-driven DW motion
is an example of the latter. Here we show that DW propagation speed driven by a
thermal gradient can be fully explained as the angular momentum transfer
between thermally generated spin current and DW. We found DW-plane rotation
speed increases as DW width decreases. Both DW propagation speed along the wire
and DW-plane rotation speed around the wire decrease with the Gilbert damping.
These facts are consistent with the angular momentum transfer mechanism, but
are distinct from the energy dissipation mechanism. We further show that
magnonic spin-transfer torque (STT) generated by a thermal gradient has both
damping-like and field-like components. By analyzing DW propagation speed and
DW-plane rotation speed, the coefficient ( \b{eta}) of the field-like STT
arising from the non-adiabatic process, is obtained. It is found that \b{eta}
does not depend on the thermal gradient; increases with uniaxial anisotropy
K_(||) (thinner DW); and decreases with the damping, in agreement with the
physical picture that a larger damping or a thicker DW leads to a better
alignment between the spin-current polarization and the local magnetization, or
a better adiabaticity.",1812.07244v2
2019-01-09,Turbulent dynamo in a weakly ionized medium,"The small-scale turbulent dynamo is an important process contributing to the
cosmic magnetization. In partially ionized astrophysical plasmas, the dynamo
growth of magnetic energy strongly depends on the coupling state between ions
and neutrals and the ion-neutral collisional damping effect. A new damping
stage of turbulent dynamo in a weakly ionized medium was theoretically
predicted by Xu \& Lazarian (2016). By carrying out a 3D two-fluid dynamo
simulation, here we for the first time numerically confirmed the physical
conditions and the linear-in-time growth of magnetic field strength of the
damping stage of dynamo. The dynamo-amplified magnetic field has a
characteristic length as the damping scale, which increases with time and can
reach the injection scale of turbulence after around eight largest
eddy-turnover times given sufficiently low ionization fraction and weak initial
magnetic field. Due to the weak coupling between ions and neutrals, most
turbulent energy carried by neutrals cannot be converted to the magnetic
energy, resulting in a relatively weak magnetic field at the end of dynamo.
This result has important implications for the growth of magnetic fields in the
partially ionized interstellar medium and shock acceleration of Galactic cosmic
rays.",1901.02893v1
2019-01-25,Quantum speed limit time for correlated quantum channel,"Memory effects play a fundamental role in the dynamics of open quantum
systems. There exist two different views on memory for quantum noises. In the
first view, the quantum channel has memory when there exist correlations
between successive uses of the channels on a sequence of quantum systems. These
types of channels are also known as correlated quantum channels. In the second
view, memory effects result from correlations which are created during the
quantum evolution. In this work we will consider the first view and study the
quantum speed limit time for a correlated quantum channel. Quantum speed limit
time is the bound on the minimal time which is needed for a quantum system to
evolve from an initial state to desired states. The quantum evolution is fast
if the quantum speed limit time is short. In this work, we will study the
quantum speed limit time for some correlated unital and correlated non-unital
channels. As an example for unital channels we choose correlated dephasing
colored noise. We also consider the correlated amplitude damping and correlated
squeezed generalized amplitude damping channels as the examples for non-unital
channels. It will be shown that the quantum speed limit time for correlated
pure dephasing colored noise is increased by increasing correlation strength,
while for correlated amplitude damping and correlated squeezed generalized
amplitude damping channels quantum speed limit time is decreased by increasing
correlation strength.",1901.08917v4
2019-02-17,Finite-size effects on sound damping in stable computer glasses,"In this brief note we comment on the recent results presented in
arXiv:1812.08736v1",1902.06225v1
2019-08-20,Synthetic Extreme-ultraviolet Emissions Modulated by Leaky Fast Sausage Modes in Solar Active Region Loops,"We study the extreme-ultraviolet (EUV) emissions modulated by leaky fast
sausage modes (FSMs) in solar active region loops and examine their
observational signatures via spectrometers like EIS. After computing fluid
variables of leaky FSMs with MHD simulations, we forward-model the intensity
and spectral properties of the Fe X 185~\AA~and Fe XII 195~\AA~lines by
incorporating non-equilibrium ionization (NEI) in the computations of the
relevant ionic fractions. The damping times derived from the intensity
variations are then compared with the wave values, namely the damping times
directly found from our MHD simulations. Our results show that in the
equilibrium ionization cases, the density variations and the intensity
variations can be either in phase or in anti-phase, depending on the loop
temperature. NEI considerably impacts the intensity variations but has only
marginal effects on the derived Doppler velocity or Doppler width. We find that
the damping time derived from the intensity can largely reflect the wave
damping time if the loop temperature is not drastically different from the
nominal formation temperature of the corresponding emission line. These results
are helpful for understanding the modulations to the EUV emissions by leaky
FSMs and hence helpful for identifying FSMs in solar active region loops.",1908.07131v1
2019-08-29,Enhancement of ultrafast demagnetization rate and Gilbert damping driven by femtosecond laser-induced spin currents in Fe81Ga19/Ir20Mn80 bilayers,"In spintronics applications, ultrafast spin dynamics have to be controlled at
femtosecond (fs) timescales via fs-laser radiation. At such ultrafast
timescales, the effect of the Gilbert damping factor {\alpha} on ultrafast
demagnetization time should be considered. In previous explorations for the
relationship between these two parameters, it was found that the theoretical
calculations based on the local spin-flip scattering model do not agree with
the experimental results. Here, we find that in Fe81Ga19(FeGa)/Ir20Mn80(IrMn)
bilayers, the unconventional IrMn thickness dependence of {\alpha} results from
the competition between spin currents pumped from the ferromagnetic (FM) FeGa
layer to the antiferromagnetic (AFM) IrMn layer and those pumped from the AFM
layer to the FM layer. More importantly, we establish a proportional
relationship between the change of the ultrafast demagnetization rate and the
enhancement of Gilbert damping induced by the spin currents via interfacial
spin chemical potential . Our work builds a bridge to connect the ultrafast
demagnetization time and Gilbert damping in ultrafast photo-induced spin
currents dominated systems, which not only explains the disagreement between
experimental and theoretical results in the relation of {\tau}_M with {\alpha},
but provides further insight into ultrafast spin dynamics as well.",1908.11084v1
2019-11-05,IW And-Type State in IM Eridani,"IW And stars are a recently recognized group of dwarf novae which are
characterized by a repeated sequence of brightening from a standstill-like
phase with damping oscillations followed by a deep dip. Kimura et al. (2019)
recently proposed a model based on thermal-viscous disk instability in a tilted
disk to reproduce the IW And-type characteristics. IM Eri experienced the IW
And-type phase in 2018 and we recorded three cycles of the (damping)
oscillation phase terminated by brightening. We identified two periods during
the IW And-type state: 4-5 d small-amplitude (often damping) oscillations and a
34-43 d long cycle. This behavior is typical for an IW And-type star. The
object gradually brightened within the long cycle before the next brightening
which terminated the (damping) oscillation phase. This observation agrees with
the increasing disk mass during the long cycle predicted by a model of
thermal-viscous disk instability in a tilted disk (Kimura et al. 2019). We,
however, did not succeed in detecting negative superhumps, which are considered
to be the signature of a tilted disk.",1911.01587v1
2019-11-28,Magnon damping in the zigzag phase of the Kitaev-Heisenberg-$Γ$ model on a honeycomb lattice,"We calculate magnon dispersions and damping in the Kitaev-Heisenberg model
with an off-diagonal exchange $\Gamma$ and isotropic third-nearest-neighbor
interaction $J_3$ on a honeycomb lattice. This model is relevant to a
description of the magnetic properties of iridium oxides $\alpha$-Li$_2$IrO$_3$
and Na$_2$IrO$_3$, and Ru-based materials such as $\alpha$-RuCl$_3$. We use an
unconventional parametrization of the spin-wave expansion, in which each
Holstein-Primakoff boson is represented by two conjugate hermitian operators.
This approach gives us an advantage over the conventional one in identifying
parameter regimes where calculations can be performed analytically. Focusing on
the parameter regime with the zigzag spin pattern in the ground state that is
consistent with experiments, we demonstrate that one such region is $\Gamma =
K>0$, where $K$ is the Kitaev coupling. Within our approach we are able to
obtain explicit analytical expressions for magnon energies and eigenstates and
go beyond the standard linear spin-wave theory approximation by calculating
magnon damping and demonstrating its role in the dynamical structure factor. We
show that the magnon damping effects in both Born and self-consistent
approximations are very significant, underscoring the importance of non-linear
magnon coupling in interpreting broad features in the neutron-scattering
spectra.",1911.12829v2
2019-12-10,A Stochastic Quasi-Newton Method for Large-Scale Nonconvex Optimization with Applications,"This paper proposes a novel stochastic version of damped and regularized BFGS
method for addressing the above problems.",1912.04456v1
2019-12-27,Ultralow mechanical damping with Meissner-levitated ferromagnetic microparticles,"Levitated nanoparticles and microparticles are excellent candidates for the
realization of extremely isolated mechanical systems, with a huge potential
impact in sensing applications and in quantum physics. Magnetic levitation
based on static fields is a particularly interesting approach, due to the
unique property of being completely passive and compatible with low
temperatures. Here, we show experimentally that micromagnets levitated above
type-I superconductors feature very low damping at low frequency and low
temperature. In our experiment, we detect 5 out of 6 rigid-body mechanical
modes of a levitated ferromagnetic microsphere, using a dc SQUID
(Superconducting Quantum Interference Device) with a single pick-up coil. The
measured frequencies are in agreement with a finite element simulation based on
ideal Meissner effect. For two specific modes we find further substantial
agreement with analytical predictions based on the image method. We measure
damping times $\tau$ exceeding $10^4$ s and quality factors $Q$ beyond $10^7$,
improving by $2-3$ orders of magnitude over previous experiments based on the
same principle. We investigate the possible residual loss mechanisms besides
gas collisions, and argue that much longer damping time can be achieved with
further effort and optimization. Our results open the way towards the
development of ultrasensitive magnetomechanical sensors with potential
applications to magnetometry and gravimetry, as well as to fundamental and
quantum physics.",1912.12252v3
2020-03-30,Optimal absorption of acoustical waves by a boundary,"In the aim to find the simplest and most efficient shape of a noise absorbing
wall to dissipate the acoustical energy of a sound wave, we consider a
frequency model described by the Helmholtz equation with a damping on the
boundary. The well-posedness of the model is shown in a class of domains with
d-set boundaries (N -- 1 $\le$ d < N). We introduce a class of admissible
Lipschitz boundaries, in which an optimal shape of the wall exists in the
following sense: We prove the existence of a Radon measure on this shape,
greater than or equal to the usual Lebesgue measure, for which the
corresponding solution of the Helmholtz problem realizes the infimum of the
acoustic energy defined with the Lebesgue measure on the boundary. If this
Radon measure coincides with the Lebesgue measure, the corresponding solution
realizes the minimum of the energy. For a fixed porous material, considered as
an acoustic absorbent, we derive the damping parameters of its boundary from
the corresponding time-dependent problem described by the damped wave equation
(damping in volume).",2003.13250v2
2020-05-08,Separatrix crossing and symmetry breaking in NLSE-like systems due to forcing and damping,"We theoretically and experimentally examine the effect of forcing and damping
on systems that can be described by the nonlinear Schr\""odinger equation
(NLSE), by making use of the phase-space predictions of the three-wave
truncation of the spectrum. In the latter, only the fundamental frequency and
the upper and lower sidebands are retained. Plane wave solutions to the NLSE
exhibit modulation instability (MI) within a frequency band determined by a
linear stability analysis. For modulation frequencies inside the MI-band, we
experimentally demonstrate that forcing and damping cause a separatrix crossing
during the evolution. Our experiments are performed on deep water waves, which
are better described by the higher-order NLSE, the Dysthe equation. We
therefore extend our analysis to this system. However, our conclusions are
general. When the system is damped by the viscosity of the water, it is pulled
outside the separatrix, which in the real space corresponds to a phase-shift of
the envelope and therefore doubles the period of the Fermi-Pasta-Ulam-Tsingou
recurrence cycle. When the system is forced by the wind, it is pulled inside
the separatrix. Furthermore, for modulation frequencies outside the
conventional MI-band, we experimentally demonstrate that contrary to the linear
prediction, we do observe a growth and decay cycle of the plane-wave
modulation. Finally, we give a theoretical demonstration that forcing the NLSE
system can induce symmetry breaking during the evolution.",2005.03931v1
2020-05-13,Damping of a micro-electromechanical oscillator in turbulent superfluid $^4$He: A novel probe of quantized vorticity in the ultra-low temperature regime,"We report a comprehensive investigation of the effects of quantum turbulence
and quantized vorticity in superfluid $^4$He on the motion of a
micro-electromechanical systems (MEMS) resonator. We find that the MEMS is
uniquely sensitive to quantum turbulence present in the fluid. To generate
turbulence in the fluid, a quartz tuning fork (TF) is placed in proximity to
the MEMS and driven at large amplitude. We observe that at low velocity, the
MEMS is damped by the turbulence, and that above a critical velocity, $v_c
\simeq 5\,$mm\,s$^{-1}$, the turbulent damping is greatly reduced. We find that
above $v_c$, the damping of the MEMS is reduced further for increasing
velocity, indicating a velocity dependent coupling between the surface of the
MEMS and the quantized vortices constituting the turbulence. We propose a model
of the interaction between vortices in the fluid and the surface of the MEMS.
The sensitivity of these devices to a small number of vortices and the almost
unlimited customization of MEMS open the door to a more complete understanding
of the interaction between quantized vortices and oscillating structures, which
in turn provides a new route for the investigation of the dynamics of single
vortices.",2005.06570v1
2020-06-10,Online PMU-Based Wide-Area Damping Control for Multiple Inter-Area Modes,"This paper presents a new phasor measurement unit (PMU)-based wide-area
damping control (WADC) method to suppress the critical inter-area modes of
large-scale power systems. Modal participation factors, estimated by a
practically model-free system identification approach, are used to select the
most suitable synchronous generators for control through the proposed WADC
algorithm. It is shown that multiple inter-area modes can be sufficiently
damped by the proposed approach without affecting the rest of the modes, while
only a few machines are needed to perform the control. The proposed technique
is applied to the IEEE 68-bus and the IEEE 145-bus systems, including the test
cases with PMU measurement noise and with missing PMUs. The simulation results
clearly demonstrate the good adaptivity of the control strategy subjected to
network model changes, its effective damping performance comparing to power
system stabilizers (PSSs), and its great potential for near real-time
implementation.",2006.05651v1
2020-06-14,A general formulation for the magnetic oscillations in two dimensional systems,"We develop a general formalism for the magnetic oscillations (MO) in two
dimensional (2D) systems. We consider general 2D Landau levels, which may
depend on other variable or indices, besides the perpendicular magnetic field.
In the ground state, we obtain expressions for the MO phase and amplitude. From
this we use a Fourier expansion to write the MO, with the first term being a
sawtooth oscillation. We also consider the effects of finite temperature,
impurities or lattice imperfections, assuming a general broadening of the
Landau levels. We develop two methods for describing these damping effects in
the MO. One in terms of the occupancy of the Landau levels, the other in terms
of reduction factors, which results in a generalization of the
Lifshits-Kosevich (LK) formula. We show that the first approach is particularly
useful at very low damping, when only the states close to the Fermi energy are
excited. In contrast, the LK formula may be more convenient at higher damping,
when only few terms are needed in its harmonic expansion. We compare different
damping situations, showing how the MO are broadened in each case. The general
formulation presented allows to relate the properties of the MO with those of
the 2D systems.",2006.07944v2
2020-08-03,Improvement on the blow-up of the wave equation with the scale-invariant damping and combined nonlinearities,"We consider in this article the damped wave equation, in the
\textit{scale-invariant case} with combined two nonlinearities, which reads as
follows: \begin{displaymath} \d (E) \hspace{1cm} u_{tt}-\Delta
u+\frac{\mu}{1+t}u_t=|u_t|^p+|u|^q, \quad \mbox{in}\ \R^N\times[0,\infty),
\end{displaymath} with small initial data.\\ Compared to our previous work
\cite{Our}, we show in this article that the first hypothesis on the damping
coefficient $\mu$, namely $\mu < \frac{N(q-1)}{2}$, can be removed, and the
second one can be extended from $(0, \mu_*/2)$ to $(0, \mu_*)$ where $\mu_*>0$
is solution of $(q-1)\left((N+\mu_*-1)p-2\right) = 4$. Indeed, owing to a
better understanding of the influence of the damping term in the global
dynamics of the solution, we think that this new interval for $\mu$ describe
better the threshold between the blow-up and the global existence regions.
Moreover, taking advantage of the techniques employed in the problem $(E)$, we
also improve the result in \cite{LT2,Palmieri} in relationship with the Glassey
conjecture for the solution of $(E)$ but without the nonlinear term $|u|^q$.
More precisely, we extend the blow-up region from $p \in (1, p_G(N+\sigma)]$,
where $\sigma$ is given by \eqref{sigma} below, to $p \in (1, p_G(N+\mu)]$
giving thus a better estimate of the lifespan in this case.",2008.02109v3
2020-08-26,Quantum Lifshitz points and fluctuation-induced first-order phase transitions in imbalanced Fermi mixtures,"We perform a detailed analysis of the phase transition between the uniform
superfluid and normal phases in spin- and mass-imbalanced Fermi mixtures. At
mean-field level we demonstrate that at temperature $T\to 0$ the gradient term
in the effective action can be tuned to zero for experimentally relevant sets
of parameters, thus providing an avenue to realize a quantum Lifshitz point. We
subsequently analyze damping processes affecting the order-parameter field
across the phase transition. We show that, in the low energy limit, Landau
damping occurs only in the symmetry-broken phase and affects exclusively the
longitudinal component of the order-parameter field. It is however unavoidably
present in the immediate vicinity of the phase transition at temperature $T=0$.
We subsequently perform a renormalization-group analysis of the system in a
situation, where, at mean-field level, the quantum phase transition is second
order (and not multicritical). We find that, at $T$ sufficiently low, including
the Landau damping term in a form derived from the microscopic action
destabilizes the renormalization group flow towards the Wilson-Fisher fixed
point. This signals a possible tendency to drive the transition weakly
first-order by the coupling between the order-parameter fluctuations and
fermionic excitations effectively captured by the Landau damping contribution
to the order-parameter action.",2008.11782v1
2020-09-10,Electron Landau Damping of Kinetic Alfvén Waves in Simulated Magnetosheath Turbulence,"Turbulence is thought to play a role in the heating of the solar wind plasma,
though many questions remain to be solved regarding the exact nature of the
mechanisms driving this process in the heliosphere. In particular, the physics
of the collisionless interactions between particles and turbulent
electromagnetic fields in the kinetic dissipation range of the turbulent
cascade remains incompletely understood. A recent analysis of an interval of
Magnetosphere Multiscale (MMS) observations has used the field-particle
correlation technique to demonstrate that electron Landau damping is involved
in the dissipation of turbulence in the Earth's magnetosheath. Motivated by
this discovery, we perform a high-resolution gyrokinetic numerical simulation
of the turbulence in the MMS interval to investigate the role of electron
Landau damping in the dissipation of turbulent energy. We employ the
field-particle correlation technique on our simulation data, compare our
results to the known velocity-space signatures of Landau damping outside the
dissipation range, and evaluate the net electron energization. We find
qualitative agreement between the numerical and observational results for some
key aspects of the energization and speculate on the nature of disagreements in
light of experimental factors, such as differences in resolution, and of
developing insights into the nature of field-particle interactions in the
presence of dispersive kinetic Alfv\'en waves.",2009.05010v1
2020-11-09,Plasmon energy losses in shear bands of metallic glass,"Shear bands resulting from plastic deformation in cold-rolled
Al$_{88}$Y$_{7}$Fe$_{5}$ metallic glass were observed to display alternating
density changes along their propagation direction. Electron-energy loss
spectroscopy (EELS) was used to investigate the volume plasmon energy losses in
and around shear bands. Energy shifts of the peak centre and changes in the
peak width (FWHM) reflecting the damping were precisely determined within an
accuracy of a few meV using an open source python module (Hyperspy) to fit the
shapes of the plasmon and zero-loss peaks with Lorentzian functions. The
maximum bulk plasmon energy shifts were calculated for the bright and dark
shear band segments relative to the matrix to be about 38 and 14 meV,
respectively. The damping was observed to be larger for the denser regions. The
analysis presented here suggests that the changes in the plasmons are caused by
two contributions: (i) Variable damping in the shear band segments due to
changes in the medium-range order (MRO). This affects the static structure
factor S(k), which, in turn, leads to either reduced or increased damping
according to the Ziman-Baym formula. (ii) The ionic density and the effective
electron mass appearing in the zero-momentum plasmon frequency formula
$E_p(q=0)$ are coupled and give rise to small variations in the plasmon energy.
The model predicts plasmon energy shifts in the order of meV.",2011.04396v3
2020-11-16,Thresholds for loss of Landau damping in longitudinal plane,"Landau damping mechanism plays a crucial role in providing single-bunch
stability in LHC, High-Luminosity LHC, other existing as well as previous and
future (like FCC) circular hadron accelerators. In this paper, the thresholds
for the loss of Landau damping (LLD) in the longitudinal plane are derived
analytically using the Lebedev matrix equation (1968) and the concept of the
emerged van Kampen modes (1983). We have found that for the commonly-used
particle distribution functions from a binomial family, the LLD threshold
vanishes in the presence of the constant inductive impedance Im$Z/k$ above
transition energy. Thus, the effect of the cutoff frequency or the resonant
frequency of a broad-band impedance on beam dynamics is studied in detail. The
findings are confirmed by direct numerical solutions of the Lebedev equation as
well as using the Oide-Yokoya method (1990). Moreover, the characteristics,
which are important for beam operation, as the amplitude of residual
oscillations and the damping time after a kick (or injection errors) are
considered both above and below the threshold. Dependence of the threshold on
particle distribution in the longitudinal phase space is also analyzed,
including some special cases with a non-zero threshold for Im$Z/k = const$. All
main results are confirmed by macro-particle simulations and consistent with
available beam measurements in the LHC.",2011.07985v1
2021-03-11,Nontrivial damping of quantum many-body dynamics,"Understanding how the dynamics of a given quantum system with many degrees of
freedom is altered by the presence of a generic perturbation is a notoriously
difficult question. Recent works predict that, in the overwhelming majority of
cases, the unperturbed dynamics is just damped by a simple function, e.g.,
exponentially as expected from Fermi's golden rule. While these predictions
rely on random-matrix arguments and typicality, they can only be verified for a
specific physical situation by comparing to the actual solution or measurement.
Crucially, it also remains unclear how frequent and under which conditions
counterexamples to the typical behavior occur. In this work, we discuss this
question from the perspective of projection-operator techniques, where
exponential damping of a density matrix occurs in the interaction picture but
not necessarily in the Schr\""odinger picture. We show that a nontrivial damping
in the Schr\""odinger picture can emerge if the dynamics in the unperturbed
system possesses rich features, for instance due to the presence of strong
interactions. This suggestion has consequences for the time dependence of
correlation functions. We substantiate our theoretical arguments by large-scale
numerical simulations of charge transport in the extended Fermi-Hubbard chain,
where the nearest-neighbor interactions are treated as a perturbation to the
integrable reference system.",2103.06646v2
2021-03-24,"Multimode piezoelectric shunt damping of thin plates with arrays of separately shunted patches, method, and experimental validation","Two-dimensional thin plates are widely used in many applications. Shunt
damping is a promising way for the attenuation of vibration of these
electromechanical systems. It enables a compact vibration damping method
without adding significant mass and volumetric occupancy. Analyzing the
dynamics of such electromechanical systems requires precise modeling tools that
properly consider the coupling between the piezoelectric elements and the host
structure. Although the concept of shunt damping has been studied extensively
in the literature, most of the studies do not provide a formulation for
modeling the multiple piezoelectric patches that are scattered on the host
structure and shunted separately. This paper presents a methodology and a
formulation for separately shunted piezoelectric patches for achieving higher
performance on vibration attenuation. The Rayleigh-Ritz method is used for
performing modal analysis and obtaining the frequency response functions of the
electro-mechanical system. The developed model includes mass and stiffness
contribution of the piezoelectric patches as well as the electromechanical
coupling effect. In this study, the piezoelectric patches are shunted via
separate electrical circuits and compared with the ones those are shunted via
interconnected electrical circuits. For verification, system-level finite
element simulations are performed in ANSYS software and compared with the
analytical model results. An experimental setup is also built to validate the
performance of the separately shunted piezoelectric patches. The effectiveness
of the method is investigated for a broader range of frequencies and it was
shown that separately shunted piezoelectric patches are more effective compared
to connected for a wide range of frequencies.",2103.13179v1
2021-03-29,Nonequilibrium Dynamics of the Chiral Quark Condensate under a Strong Magnetic Field,"Strong magnetic fields impact quantum-chromodynamics (QCD) properties in
several situations; examples include the early universe, magnetars, and
heavy-ion collisions. These examples share a common trait: time evolution. A
prominent QCD property impacted by a strong magnetic field is the quark
condensate, an approximate order parameter of the QCD transition between a
high-temperature quark-gluon phase and a low-temperature hadronic phase. We use
the linear sigma model with quarks to address the quark condensate time
evolution under a strong magnetic field. We use the closed time path formalism
of nonequilibrium quantum field theory to integrate out the quarks and obtain a
mean-field Langevin equation for the condensate. The Langevin equation features
dissipation and noise kernels controlled by a damping coefficient. We compute
the damping coefficient for magnetic field and temperature values achieved in
peripheral relativistic heavy-ion collisions and solve the Langevin equation
for a temperature quench scenario. The magnetic field changes the dissipation
and noise pattern by increasing the damping coefficient compared to the
zero-field case. An increased damping coefficient increases fluctuations and
time scales controlling condensate's short-time evolution, a feature that can
impact hadron formation at the QCD transition. The formalism developed here can
be extended to include other order parameters, hydrodynamic modes, and system's
expansion to address magnetic field effects in complex settings as heavy-ion
collisions, the early universe, and magnetars.",2103.15665v1
2021-04-09,Taming the pinch singularities in the two-loop neutrino self-energy in a medium,"We consider the calculation of the thermal self-energy of a neutrino that
propagates in a medium composed of fermions and scalars interacting via a
Yukawa-type coupling, in the case that the neutri no energy is much larger than
the fermion and scalar masses, as well as the temperature and chemical
potentials of the background. In this kinematic regime the one-loop
contribution to the imaginary part of the self-energy is negligible. We
consider the two-loop contribution and we encounter the so-called pinch
singularities which are known to arise in higher loop self-energy calculations
in Thermal Field Theory. With a judicious use of the properties and
parametrizations of the thermal propagators the singularities are treated
effectively and actually disappear. From the imaginary part of the self-energy,
we obtain a precise formula for the damping matrix expressed in terms of
integrals over the background particle distributions. The formulas predict a
specific dependence of the damping terms on the neutrino energy, depending on
the background conditions. For guidance to estimating the effects in specific
contexts, we compute the damping terms for several limiting cases of the
momentum distribution functions of the background particles. We discuss briefly
the connection between the results of our calculations for the damping matrix
and the decoherence effects described in terms of the Lindblad equation.",2104.04459v2
2021-06-16,Spin-Torque-driven Terahertz Auto Oscillations in Non-Collinear Coplanar Antiferromagnets,"We theoretically and numerically study the terahertz auto oscillations in
thin-film metallic non-collinear coplanar antiferromagnets (AFMs), such as
$\mathrm{Mn_{3}Sn}$ and $\mathrm{Mn_{3}Ir}$, under the effect of anti-damping
spin-torque with spin polarization perpendicular to the plane of the film. To
obtain the order parameter dynamics in these AFMs, we solve three
Landau-Lifshitz-Gilbert equations coupled by exchange interactions assuming
both single- and multi-domain (micromagnetics) dynamical processes. In the
limit of strong exchange interaction, the oscillatory dynamics of the order
parameter in these AFMs, which have opposite chiralities, could be mapped to
that of a linear damped-driven pendulum in the case of $\mathrm{Mn_{3}Sn}$, and
a non-linear damped-driven pendulum in case of $\mathrm{Mn_{3}Ir}$. The
theoretical framework allows us to identify the input current requirements as a
function of the material and geometry parameters for exciting an oscillatory
response. We also obtain a closed-form approximate solution of the oscillation
frequency for large input currents in case of both $\mathrm{Mn_{3}Ir}$ and
$\mathrm{Mn_{3}Sn}$. Our analytical predictions of threshold current and
oscillation frequency agree well with the numerical results and thus can be
used as compact models to design and optimize the auto oscillator. Employing a
circuit model, based on the principle of tunnel anisotropy magnetoresistance,
we present detailed models of the output power and efficiency versus
oscillation frequency of the auto oscillator. Finally, we explore the spiking
dynamics of two unidirectional as well as bidirectional coupled AFM oscillators
using non-linear damped-driven pendulum equations.",2106.08528v2
2021-06-20,Life-cycle assessment for flutter probability of a long-span suspension bridge based on field monitoring data,"Assessment of structural safety status is of paramount importance for
existing bridges, where accurate evaluation of flutter probability is essential
for long-span bridges. In current engineering practice, at the design stage,
flutter critical wind speed is usually estimated by the wind tunnel test, which
is sensitive to modal frequencies and damping ratios. After construction,
structural properties of existing structures will change with time due to
various factors, such as structural deteriorations and periodic environments.
The structural dynamic properties, such as modal frequencies and damping
ratios, cannot be considered as the same values as the initial ones, and the
deteriorations should be included when estimating the life-cycle flutter
probability. This paper proposes an evaluation framework to assess the
life-cycle flutter probability of long-span bridges considering the
deteriorations of structural properties, based on field monitoring data. The
Bayesian approach is employed for modal identification of a suspension bridge
with the main span of 1650 m, and the field monitoring data during 2010-2015 is
analyzed to determine the deterioration functions of modal frequencies and
damping ratios, as well as their inter-seasonal fluctuations. According to the
historical trend, the long-term structural properties can be predicted, and the
probability distributions of flutter critical wind speed for each year in the
long term are calculated. Consequently, the life-cycle flutter probability is
estimated, based on the predicted modal frequencies and damping ratios.",2106.10694v1
2021-07-17,Theoretical and numerical study of vibrational resonance in a damped softening Duffing oscillator,"We study the possibility of occurrence of vibrational resonance in a
softening Duffing oscillator in the underdamped and overdamped cases both
theoretically as well as numerically. The oscillator is driven by two periodic
forces. Numerically we find that in the underdamped case two oscillatory
solutions are obtained in a limited range of the parameters considered (damping
coefficient and amplitude of the high frequency force) for a fixed frequency
and amplitude of the low frequency periodic force depending on the initial
conditions. These solutions have distinct response amplitude to the low
frequency force. When damping is gradually increased, only one oscillatory
solution is observed. Vibrational resonance is observed in both the regions of
oscillation. The analytical approximation yields only one oscillatory solution
for all damping values. Analytically, the peak in the area bounded by the phase
portrait as a function of the amplitude of the high frequency force is
connected to vibrational resonance. Also, the values of the frequency of the
low frequency forcing and the amplitude of the high frequency forcing at which
vibrational resonance is found to occur are obtained. In the overdamped case,
vibrational resonance is not observed for the softening Duffing oscillator thus
showing a marked contrast to the overdamped bistable oscillator",2107.08302v1
2021-07-28,Optimal gamma-ray selections for monochromatic line searches with DAMPE,"The DArk Matter Particle Explorer (DAMPE) is a space high-energy cosmic-ray
detector covering a wide energy band with a high energy resolution. One of the
key scientific goals of DAMPE is to carry out indirect detection of dark matter
by searching for high-energy gamma-ray line structure. To promote the
sensitivity of gamma-ray line search with DAMPE, it is crucial to improve the
acceptance and energy resolution of gamma-ray photons. In this paper, we
quantitatively prove that the photon sample with the largest ratio of
acceptance to energy resolution is optimal for line search. We therefore
develop a line-search sample specifically optimized for the line search.
Meanwhile, in order to increase the statistics, we also selected the so called
BGO-only photons that convert into $e^+e^-$ pairs only in the BGO calorimeter.
The standard, the line-search, and the BGO-only photon samples are then tested
for line search individually and collectively. The results show that a
significantly improved limit could be obtained from an appropriate combination
of the date sets, and the increase is about 20\% for the highest case compared
with using the standard sample only.",2107.13208v2
2021-07-28,Magnetic field induced asymmetric splitting of the output signal,"In this paper we have investigated the dynamics of a damped harmonic
oscillator in the presence of an electromagnetic field. The transients for the
two dimensional harmonic oscillator imply about the modulation of the frequency
of the oscillator by the velocity dependent non conservative force from an
applied magnetic field. Except a special condition, the motion is in general
quasi periodic nature even in the absence of damping. Another interesting
finding is that the magnetic field may induce an asymmetric splitting of the
spectrum of the output signal with two peaks in the case of a driven damped two
dimensional harmonic oscillator. One more additional peak may appear for the
three dimensional case. In some cases the spectrum may have similarity with the
Normal Zeeman Effect. At the same time one may observe to appear the anti
resonance phenomenon even for the driven damped cyclotron motion where the
system with the purely non conservative force fields is driven by an electric
field. Finally, our calculation exhibits how the magnetic field can modulate
the phase difference (between input and output signals) and the efficiency like
quantity of the energy storing process. Thus the present study might be
applicable in the areas related to the refractive index, the barrier crossing
dynamics and autonomous stochastic resonance, respectively.",2107.13305v1
2021-07-28,Evolution of a Mode of Oscillation Within Turbulent Accretion Disks,"We investigate the effects of subsonic turbulence on a normal mode of
oscillation [a possible origin of the high-frequency quasi-periodic
oscillations (HFQPOs) within some black hole accretion disks]. We consider
perturbations of a time-dependent background (steady state disk plus
turbulence), obtaining an oscillator equation with stochastic damping, (mildly)
nonlinear restoring, and stochastic driving forces. The (long-term) mean values
of our turbulent functions vanish. In particular, turbulence does not damp the
oscillation modes, so `turbulent viscosity' is not operative. However, the
frequency components of the turbulent driving force near that of the mode can
produce significant changes in the amplitude of the mode. Even with an
additional (phenomenological constant) source of damping, this leads to an
eventual `blowout' (onset of effects of nonlinearity) if the turbulence is
sufficiently strong or the damping constant is sufficiently small. The
infrequent large increases in the energy of the mode could be related to the
observed low duty cycles of the HFQPOs. The width of the peak in the power
spectral density (PSD) is proportional to the amount of nonlinearity. A
comparison with observed continuum PSDs indicates the conditions required for
visibility of the mode.",2107.13546v1
2021-07-31,Oscillating scalar dissipating in a medium,"We study how oscillations of a scalar field condensate are damped due to
dissipative effects in a thermal medium. Our starting point is a non-linear and
non-local condensate equation of motion descending from a 2PI-resummed
effective action derived in the Schwinger-Keldysh formalism appropriate for
non-equilibrium quantum field theory. We solve this non-local equation by means
of multiple-scale perturbation theory appropriate for time-dependent systems,
obtaining approximate analytic solutions valid for very long times. The
non-linear effects lead to power-law damping of oscillations, that at late
times transition to exponentially damped ones characteristic for linear
systems. These solutions describe the evolution very well, as we demonstrate
numerically in a number of examples. We then approximate the non-local equation
of motion by a Markovianised one, resolving the ambiguities appearing in the
process, and solve it utilizing the same methods to find the very same leading
approximate solution. This comparison justifies the use of Markovian equations
at leading order. The standard time-dependent perturbation theory in comparison
is not capable of describing the non-linear condensate evolution beyond the
early time regime of negligible damping. The macroscopic evolution of the
condensate is interpreted in terms of microphysical particle processes. Our
results have implications for the quantitative description of the decay of
cosmological scalar fields in the early Universe, and may also be applied to
other physical systems.",2108.00254v1
2021-08-02,Large-amplitude longitudinal oscillations in solar prominences simulated with different resolutions,"Large-amplitude longitudinal oscillations (LALOs) in solar prominences have
been widely studied in the last decades. However, their damping and
amplification mechanisms are not well understood. In this study, we investigate
the attenuation and amplification of LALOs using high-resolution numerical
simulations with progressively increasing spatial resolutions. We performed
time-dependent numerical simulations of LALOs using the 2D magnetic
configuration that contains a dipped region. After the prominence mass loading
in the magnetic dips, we triggered LALOs by perturbing the prominence mass
along the magnetic field. We performed the experiments with four values of
spatial resolution. In the simulations with the highest resolution, the period
shows a good agreement with the pendulum model. The convergence experiment
revealed that the damping time saturates at the bottom prominence region with
improving the resolution, indicating the existence of a physical reason for the
damping of oscillations. At the prominence top, the oscillations are amplified
during the first minutes and then are slowly attenuated. The characteristic
time suggests more significant amplification in the experiments with the
highest spatial resolution. The analysis revealed that the energy exchange
between the bottom and top prominence regions is responsible for the
attenuation and amplification of LALOs. The high-resolution experiments are
crucial for the study of the periods and the damping mechanism of LALOs. The
period agrees with the pendulum model only when using high enough spatial
resolution. The results suggest that numerical diffusion in simulations with
insufficient spatial resolution can hide important physical mechanisms, such as
amplification of oscillations.",2108.01143v1
2021-08-05,Complexity analysis of quantum teleportation via different entangled channels in the presence of noise,"Quantum communication is one of the hot topics in quantum computing, where
teleportation of a quantum state has a slight edge and gained significant
attention from researchers. A large number of teleportation schemes have
already been introduced so far. Here, we compare the teleportation of a single
qubit message among different entangled channels such as the two-qubit Bell
channel, three-qubit GHZ channel, two- and three-qubit cluster states, the
highly entangled five-qubit Brown \emph{et al.} state and the six-qubit Borras
\emph{et al.} state. We calculate and compare the quantum costs in each of the
cases. Furthermore, we study the effects of six noise models, namely bit-flip
noise, phase-flip noise, bit-phase flip noise, amplitude damping, phase damping
and the depolarizing error that may affect the communication channel used for
the teleportation. An investigation on the variation of the initial state's
fidelity with respect to the teleported state in the presence of the noise
model is performed. A visual representation of the variation of fidelity for
various values of the noise parameter $\eta$ is done through a graph plot. It
is observed that as the value of noise parameter in the range $\eta \in
[0,0.5]$, the fidelity decreases in all the entangled channels under all the
noise models. After that, in the Bell channel, GHZ channel and three-qubit
cluster state channel, the fidelity shows an upward trend under all the noise
models. However, in the other three channels, the fidelity substantially
decreases in the case of amplitude damping, phase damping and depolarizing
noise, and even it reaches zero for $\eta = 1$ in Brown \emph{et al.} and
Borras \emph{et al.} channels.",2108.02641v1
2021-08-06,Noncontact friction: Role of phonon damping and its nonuniversality,"While obtaining theoretical predictions for dissipation during sliding motion
is a difficult task, one regime that allows for analytical results is the
so-called noncontact regime, where a probe is weakly interacting with the
surface over which it moves. Studying this regime for a model crystal, we
extend previously obtained analytical results and confirm them quantitatively
via particle based computer simulations. Accessing the subtle regime of weak
coupling in simulations is possible via use of Green-Kubo relations. The
analysis allows to extract and compare the two paradigmatic mechanisms that
have been found to lead to dissipation: phonon radiation, prevailing even in a
purely elastic solid, and phonon damping, e.g., caused by viscous motion of
crystal atoms. While phonon radiation is dominant at large probe-surface
distances, phonon damping dominates at small distances. Phonon radiation is
furthermore a pairwise additive phenomenon so that the dissipation due to
interaction with different parts (areas) of the surface adds up. This additive
scaling results from a general one-to-one mapping between the mean
probe-surface force and the friction due to phonon radiation, irrespective of
the nature of the underlying pair interaction. In contrast, phonon damping is
strongly nonadditive, and no such general relation exists. We show that for
certain cases, the dissipation can even {\it decrease} with increasing surface
area the probe interacts with. The above properties, which are rooted in the
spatial correlations of surface fluctuations, are expected to have important
consequences when interpreting experimental measurements, as well as scaling
with system size.",2108.03025v3
2021-09-14,Design of a HOM-Damped 166.6 MHz Compact Quarter-Wave beta=1 Superconducting Cavity for High Energy Photon Source,"Superconducting cavities with low RF frequencies and heavy damping of higher
order modes (HOM) are desired for the main accelerator of High Energy Photon
Source (HEPS), a 6 GeV synchrotron light source promising ultralow emittance
currently under construction in Beijing. A compact 166.6 MHz superconducting
cavity was proposed adopting a quarter-wave beta=1 geometry. Based on the
successful development of a proof-of-principle cavity, a HOM-damped 166.6 MHz
compact superconducting cavity was subsequently designed. A ferrite damper was
installed on the beam pipe to reduce HOM impedance below the stringent
threshold of coupled-bunch instabilities. Being compact, RF field heating on
the cavity vacuum seal was carefully examined against quenching the NbTi
flange. The cavity was later dressed with a helium vessel and the tuning
mechanism was also realized. Excellent RF and mechanical properties were
eventually achieved. Finally, the two-cavity string was designed to ensure
smooth transitions among components and proper shielding of synchrotron light.
This paper presents a complete design of a fully dressed HOM-damped
low-frequency beta=1 superconducting cavity for HEPS.",2109.06560v1
2021-11-13,Effects of microplastics and surfactants on surface roughness of water waves,"In this paper, we study the flow physics underlying the recently developed
remote sensing capability of detecting oceanic microplastics, which is based on
the measurable surface roughness reduction induced by the presence of
microplastics on the ocean surface. In particular, we are interested in whether
this roughness reduction is caused by the microplastics as floating particles,
or by the surfactants which follow similar transport paths as microplastics.
For this purpose, we experimentally test the effects of floating particles and
surfactants on surface roughness, quantified by the mean square slope (MSS),
with waves generated by a mechanical wave maker or by wind. For microplastics,
we find that their effect on wave energy and MSS critically depends on the
surface area fraction of coverage, irrespective of the particle sizes in the
test range. The damping by particles is observed only for fractions above
$O(5-10\%)$, which is much higher than the realistic ocean condition. For
surfactants, their damping effect on mechanically generated irregular waves
generally increases with the concentration of surfactants, but no optimal
concentration corresponding to maximum damping is observed, in contrast to
previous studies based on monochromatic waves. In wind-wave experiments, the
presence of surfactants suppresses the wave generation, due to the combined
effects of reduced wind shear stress and increased wave damping. For the same
wind speed, the wind stress is identified to depend on the concentration of
surfactants with a power-law relation. The implications of these findings to
remote sensing are discussed.",2111.07021v1
2021-11-15,"Convergence Analysis of A Second-order Accurate, Linear Numerical Scheme for The Landau-Lifshitz Equation with Large Damping Parameters","A second order accurate, linear numerical method is analyzed for the
Landau-Lifshitz equation with large damping parameters. This equation describes
the dynamics of magnetization, with a non-convexity constraint of unit length
of the magnetization. The numerical method is based on the second-order
backward differentiation formula in time, combined with an implicit treatment
of the linear diffusion term and explicit extrapolation for the nonlinear
terms. Afterward, a projection step is applied to normalize the numerical
solution at a point-wise level. This numerical scheme has shown extensive
advantages in the practical computations for the physical model with large
damping parameters, which comes from the fact that only a linear system with
constant coefficients (independent of both time and the updated magnetization)
needs to be solved at each time step, and has greatly improved the numerical
efficiency. Meanwhile, a theoretical analysis for this linear numerical scheme
has not been available. In this paper, we provide a rigorous error estimate of
the numerical scheme, in the discrete $\ell^{\infty}(0,T; \ell^2) \cap
\ell^2(0,T; H_h^1)$ norm, under suitable regularity assumptions and reasonable
ratio between the time step-size and the spatial mesh-size. In particular, the
projection operation is nonlinear, and a stability estimate for the projection
step turns out to be highly challenging. Such a stability estimate is derived
in details, which will play an essential role in the convergence analysis for
the numerical scheme, if the damping parameter is greater than 3.",2111.07537v1
2021-11-17,United Nation Security Council in Quantum World: Experimental Realization of Quantum Anonymous Veto Protocols using IBM Quantum Computer,"United Nation (UN) security council has fifteen members, out of which five
permanent members of the council can use their veto power against any
unfavorable decision taken by the council. In certain situation, a member using
right to veto may prefer to remain anonymous. This need leads to the
requirement of the protocols for anonymous veto which can be viewed as a
special type of voting. Recently, a few protocols for quantum anonymous veto
have been designed which clearly show quantum advantages in ensuring anonymity
of the veto. However, none of the efficient protocols for quantum anonymous
veto have yet been experimentally realized. Here, we implement 2 of those
protocols for quantum anonymous veto using an IBM quantum computer named IBMQ
Casablanca and different quantum resources like Bell, GHZ and cluster states.
In this set of proof-of-principle experiments, it's observed that using the
present technology, a protocol for quantum anonymous veto can be realized
experimentally if the number of people who can veto remains small as in the
case of UN council. Further, it's observed that Bell state based protocol
implemented here performs better than the GHZ/cluster state based
implementation of the other protocol in an ideal scenario as well as in
presence of different types of noise (amplitude damping, phase damping,
depolarizing and bit-flip noise). In addition, it's observed that based on
diminishing impact on fidelity, different noise models studied here can be
ordered in ascending order as phase damping, amplitude damping, depolarizing,
bit-flip.",2111.09028v1
2021-12-03,The Importance of Electron Landau Damping for the Dissipation of Turbulent Energy in Terrestrial Magnetosheath Plasma,"Heliospheric plasma turbulence plays a key role in transferring the energy of
large-scale magnetic field and plasma flow fluctuations to smaller scales where
the energy can be dissipated, ultimately leading to plasma heating.
High-quality measurements of electromagnetic fields and electron velocity
distributions by the Magnetospheric Multiscale (MMS) mission in Earth's
magnetosheath present a unique opportunity to characterize plasma turbulence
and to determine the mechanisms responsible for its dissipation. We apply the
field-particle correlation technique to a set of twenty MMS magnetosheath
intervals to identify the dissipation mechanism and quantify the dissipation
rate. It is found that 95% of the intervals have velocity-space signatures of
electron Landau damping that are quantitatively consistent with linear kinetic
theory for the collisionless damping of kinetic Alfv\'en waves. About 75% of
the intervals contain asymmetric signatures, indicating a local imbalance of
kinetic Alfv\'en wave energy flux in one direction along the magnetic field
than the other. About one third of the intervals have an electron energization
rate with the same order-of-magnitude as the estimated turbulent cascade rate,
suggesting that electron Landau damping plays a significant, and sometimes
dominant, role in the dissipation of the turbulent energy in these
magnetosheath intervals.",2112.02171v1
2022-01-01,Extremely strong DLAs at high redshift: Gas cooling and H$_2$ formation,"We present a spectroscopic investigation with VLT/X-shooter of seven
candidate extremely strong damped Lyman-$\alpha$ absorption systems (ESDLAs,
$N(\text{HI})\ge 5\times 10^{21}$ cm$^{-2}$) observed along quasar sightlines.
We confirm the extremely high column densities, albeit slightly (0.1~dex) lower
than the original ESDLA definition for four systems. We measured low-ionisation
metal abundances and dust extinction for all systems. For two systems we also
found strong associated H$_2$ absorption $\log
N(\text{H$_2$)[cm$^{-2}$]}=18.16\pm0.03$ and $19.28\pm0.06$ at $z=3.26$ and
$2.25$ towards J2205+1021 and J2359+1354, respectively), while for the
remaining five we measured conservative upper limits on the H$_2$ column
densities of typically $\log N(\text{H$_2$)[cm$^{-2}$]}<17.3$. The increased
H$_2$ detection rate ($10-55$% at 68% confidence level) at high HI column
density compared to the overall damped Lyman-$\alpha$ population ($\sim 5-10$%)
confirms previous works. We find that these seven ESDLAs have similar observed
properties as those previously studied towards quasars and gamma-ray burst
afterglows, suggesting they probe inner regions of galaxies. We use the
abundance of ionised carbon in excited fine-structure level to calculate the
cooling rates through the CII $\lambda$158$\mu$m emission, and compare them
with the cooling rates from damped Lyman-$\alpha$ systems in the literature. We
find that the cooling rates distribution of ESDLAs also presents the same
bimodality as previously observed for the general (mostly lower HI column
density) damped Lyman-$\alpha$ population.",2201.00245v1
2022-01-05,Stability of the discrete time-crystalline order in spin-optomechanical and open cavity QED systems,"Discrete time crystals (DTC) have been demonstrated experimentally in several
different quantum systems in the past few years. Spin couplings and cavity
losses have been shown to play crucial roles for realizing DTC order in open
many-body systems out of equilibrium. Recently, it has been proposed that
eternal and transient DTC can be present with an open Floquet setup in the
thermodynamic limit and in the deep quantum regime with few qubits,
respectively. In this work, we consider the effects of spin damping and spin
dephasing on the DTC order in spin-optomechanical and open cavity systems in
which the spins can be all-to-all coupled. In the thermodynamic limit, it is
shown that the existence of dephasing can destroy the coherence of the system
and finally lead the system to its trivial steady state. Without dephasing,
eternal DTC is displayed in the weak damping regime, which may be destroyed by
increasing the all-to-all spin coupling or the spin damping. By contrast, the
all-to-all coupling is constructive to the DTC in the moderate damping regime.
We also focus on a model which can be experimentally realized by a suspended
hexagonal boron nitride (hBN) membrane with a few spin color centers under
microwave drive and Floquet magnetic field. Signatures of transient DTC
behavior are demonstrated in both weak and moderate dissipation regimes without
spin dephasing. Relevant experimental parameters are also discussed for
realizing transient DTC order in such an hBN optomechanical system.",2201.01568v2
2022-01-20,Sharp resolvent estimate for the Baouendi-Grushin operator and applications,"In this article we study the semiclassical resolvent estimate for the
non-selfadjoint Baouendi-Grushin operator on the two-dimensional torus
$\mathbb{T}^2=\mathbb{R}^2/(2\pi\mathbb{Z})^2$ with H\""older dampings. The
operator is subelliptic degenerating along the vertical direction at $x=0$. We
exhibit three different situations:
  (i) the damping region verifies the geometric control condition with respect
to both the non-degenerate Hamiltonian flow and the vertical subelliptic flow;
  (ii) the undamped region contains a horizontal strip;
  (iii) the undamped part is a line. In all of these situations, we obtain
sharp resolvent estimates. Consequently, we prove the optimal energy decay rate
for the associated damped waved equations. For (i) and (iii), our results are
in sharp contrast to the Laplace resolvent since the optimal bound is governed
by the quasimodes in the subelliptic regime. While for (ii), the optimality is
governed by the quasimodes in the elliptic regime, and the optimal energy decay
rate is the same as for the classical damped wave equation on $\mathbb{T}^2$.
  Our analysis contains the study of adapted two-microlocal semiclassical
measures, construction of quasimodes and refined Birkhoff normal-form
reductions in different regions of the phase-space. Of independent interest, we
also obtain the propagation theorem for semiclassical measures of quasimodes
microlocalized in the subelliptic regime.",2201.08189v2
2022-02-24,Coherence of ion cyclotron resonance for damping ion cyclotron waves in space plasmas,"Ion cyclotron resonance is one of the fundamental energy conversion processes
through field-particle interaction in collisionless plasmas. However, the key
evidence for ion cyclotron resonance (i.e., the coherence between
electromagnetic fields and the ion phase space density) and the resulting
damping of ion cyclotron waves (ICWs) has not yet been directly observed.
Investigating the high-quality measurements of space plasmas by the
Magnetospheric Multiscale (MMS) satellites, we find that both the wave
electromagnetic field vectors and the bulk velocity of the disturbed ion
velocity distribution rotate around the background magnetic field. Moreover, we
find that the absolute gyro-phase angle difference between the center of the
fluctuations in the ion velocity distribution functions and the wave electric
field vectors falls in the range of (0, 90) degrees, consistent with the
ongoing energy conversion from wave-fields to particles. By invoking plasma
kinetic theory, we demonstrate that the field-particle correlation for the
damping ion cyclotron waves in our theoretical model matches well with our
observations. Furthermore, the wave electric field vectors ($\delta
\mathbf{E'}_{\mathrm {wave,\perp}}$), the ion current density ($\delta
\mathbf{J}_\mathrm {i,\perp}$) and the energy transfer rate ($\delta
\mathbf{J}_\mathrm {i,\perp}\cdot \delta \mathbf{E'}_{\mathrm {wave,\perp}}$)
exhibit quasi-periodic oscillations, and the integrated work done by the
electromagnetic field on the ions are positive, indicates that ions are mainly
energized by the perpendicular component of the electric field via cyclotron
resonance. Therefore, our combined analysis of MMS observations and kinetic
theory provides direct, thorough, and comprehensive evidence for ICW damping in
space plasmas.",2202.11967v1
2022-03-15,Search for gamma-ray line signals around the black hole at the galactic center with DAMPE observation,"The adiabatic growth of a black hole (BH) may enhance the dark matter (DM)
density surrounding it, causing a spike in the DM density profile. The spike
around the supermassive BH at the center of the Milky Way may lead to a
dramatic enhancement of the gamma-ray flux of DM annihilation from the galactic
center (GC). In this work, we analyze the gamma-ray data of the innermost
region (i.e., the inner 1$^\circ$) of the GC to search for potential line-like
signals from the BH spike. Such line-like signals could be generated in the
process of DM particles annihilating into double photons. We adopt the
gamma-ray data from the Dark Matter Particle Explorer (DAMPE). Although the
DAMPE has a much smaller effective area than the Fermi-LAT, the gamma-ray line
search can benefit from its unprecedented high energy resolution. No
significant line-like signals are found in our analysis. We derive upper limits
on the cross section of the annihilation based on this non-detection. We find
that despite the DAMPE's small effective area for photon detection, we can
still place strong constraints on the cross section ($\left<\sigma
v\right>\lesssim10^{-27}\,{\rm cm^3\,s^{-1}}$) in the spike scenario due to the
very bright model-expected flux from the spike. Our results indicate that
either DM does not annihilate primarily through the $\gamma\gamma$ channel in
the mass range we considered or no sharp density spike is present at the GC.",2203.08078v1
2022-03-15,Optimal Damping with Hierarchical Adaptive Quadrature for Efficient Fourier Pricing of Multi-Asset Options in Lévy Models,"Efficiently pricing multi-asset options is a challenging problem in
quantitative finance. When the characteristic function is available,
Fourier-based methods are competitive compared to alternative techniques
because the integrand in the frequency space often has a higher regularity than
that in the physical space. However, when designing a numerical quadrature
method for most Fourier pricing approaches, two key aspects affecting the
numerical complexity should be carefully considered: (i) the choice of damping
parameters that ensure integrability and control the regularity class of the
integrand and (ii) the effective treatment of high dimensionality. We propose
an efficient numerical method for pricing European multi-asset options based on
two complementary ideas to address these challenges. First, we smooth the
Fourier integrand via an optimized choice of the damping parameters based on a
proposed optimization rule. Second, we employ sparsification and
dimension-adaptivity techniques to accelerate the convergence of the quadrature
in high dimensions. The extensive numerical study on basket and rainbow options
under the multivariate geometric Brownian motion and some L\'evy models
demonstrates the advantages of adaptivity and the damping rule on the numerical
complexity of quadrature methods. Moreover, for the tested two-asset examples,
the proposed approach outperforms the COS method in terms of computational
time. Finally, we show significant speed-up compared to the Monte Carlo method
for up to six dimensions.",2203.08196v4
2022-03-25,Nonlinear damped spatially periodic breathers and the emergence of soliton-like rogue waves,"The spatially periodic breather solutions (SPBs) of the nonlinear
Schr\""odinger equation, prominent in modeling rogue waves, are unstable. In
this paper we numerically investigate the effects of nonlinear dissipation and
higher order nonlinearities on the routes to stability of the SPBs in the
framework of the nonlinear damped higher order nonlinear Schr\""odinger
(NLD-HONLS) equation. The initial data used in the experiments are generated by
evaluating exact SPB solutions at time $T_0$. The number of instabilities of
the background Stokes wave and the damping strength are varied. The Floquet
spectral theory of the NLS equation is used to interpret and provide a
characterization of the perturbed dynamics in terms of nearby solutions of the
NLS equation. Significantly, as $T_0$ is varied, tiny bands of complex spectrum
are observed to pinch off in the Floquet decomposition of the NLD-HONLS data,
reflecting the breakup of the SPB into a waveform that is close to either a one
or two ""soliton-like"" structure. For wide ranges of $T_0$, i.e. for solutions
initialized in the early to middle stage of the development of the MI, all
rogue waves are observed to occur when the spectrum is close to a one or two
soliton-like state. When the solutions are initialized as the MI is saturating,
rogue waves also can occur after the spectrum has left a soliton-like state.
Other novel features arise due to nonlinear damping: enhanced asymmetry, two
timescales in the evolution of the spectrum and a delay in the growth of
instabilities due to frequency downshifting.",2203.13488v2
2022-03-25,Investigating the effect of noise channels on the quality of unitary t-designs,"Unitary t-designs have a wide variety of applications in quantum information
theory, such as quantum data encryption and randomised benchmarking. However,
experimental realisations of t-designs are subject to noise. Here we
investigate the effect of noise channels on the quality of single-qubit
t-designs. The noise channels we study are bit flips, phase flips, bit and
phase flips, phase damping, amplitude damping, and depolarising noise. We
consider two noise models: the first has noise applied before the t-design
unitary operations, while the second has noise applied after the unitary
operations. We show that the single-qubit 1-design is affected only by
amplitude damping, while numeric results obtained for the 2-, 3-, 4-, and
5-designs suggest that a 2t-design is significantly more sensitive to noise
than a (2t-1)-design and that, with the exception of amplitude damping, a
(2t+1)-design is as sensitive to noise as a 2t-design. Numeric results also
reveal substantial variations in sensitivity to noise throughout the Bloch
sphere. In particular, t-designs appear to be most sensitive to noise when
acting on pure states and least sensitive to noise for the maximally mixed
state. For depolarising noise, we show that our two noise models are
equivalent, and for the other noise channels, numeric results obtained for the
model where noise is applied after the unitaries reflect the transformation of
the noise channel into a depolarising channel, an effect exploited in
randomised benchmarking with 2-designs.",2203.13771v2
2022-04-25,Geometrical aspects of contact mechanical systems and field theories,"Many important theories in modern physics can be stated using differential
geometry. Symplectic geometry is the natural framework to deal with autonomous
Hamiltonian mechanics. This admits several generalizations for nonautonomous
systems, both regular and singular. Some of these extensions are the subject of
this thesis.
  Recently there has been a growing interest in studying dissipative mechanical
systems from a geometric perspective using contact geometry. In this thesis we
review what has been done in this topic and go deeper, studying symmetries and
dissipated quantities of contact systems, and developing the Skinner-Rusk
formalism for these systems.
  With regard to classical field theory, we introduce the notion of
k-precosymplectic manifold and use it to give a geometric description of
singular nonautonomous field theories. We also devise a constraint algorithm
for these systems.
  Field theories with damping are described through a modification of the De
Donder-Weyl Hamiltonian field theory. This is achieved by combining contact
geometry and k-symplectic structures, resulting in the k-contact formalism. We
introduce two notions of dissipation laws, generalizing the concept of
dissipated quantity. These developments are also applied to Lagrangian field
theory. The Skinner-Rusk formulation for k-contact systems is described in
detail and we show how to recover the Lagrangian and Hamiltonian formalisms
from it.
  Throughout the thesis we present several examples in mechanics and field
theory. The most remarkable mechanical examples are the damped harmonic
oscillator, the motion in a gravitational field with friction, the parachute
equation and the damped simple pendulum. In field theory, we study the damped
vibrating string, the Burgers' equation, the Klein-Gordon equation and its
relation with the telegrapher's equation, and the Maxwell's equations with
dissipation.",2204.11537v1
2022-06-20,Swinging a playground swing: torque controls for inducing sustained oscillations,"Models of a playground swing have been studied since the 1960s. However, in
most of them, the position of the swinger is controlled directly. This
simplifies the problem but hides the mechanics of torques applied to keep the
swing moving in a regular pattern. This article studies these mechanics. Two
models of a swing with torques as controls that we consider are identical to
popular models of modern robotics: the Acrobot and reaction wheel pendulum.
However, the control task of sustaining the swing's regular oscillations by a
static feedback control is new and challenging, especially when damping in the
joint connecting the swing to the frame is considered. We develop two types of
controls to accomplish this task. One works for small damping and is based on
linearizing the undamped system by a suitable preliminary feedback control. The
other works for large damping. In the steady state, the resulting closed-loop
system describes a harmonically driven damped pendulum (a simple system known
for its complex behavior), including chaotic motion for some parameter values.
To address such complexities, we build free parameters into the controls, then
adjust them based on simulations to avoid chaos and achieve regular
oscillations that are seen on playgrounds.",2206.09579v1
2022-07-01,Frequency beating and damping of breathing oscillations of a harmonically trapped one-dimensional quasicondensate,"We study the breathing (monopole) oscillations and their damping in a
harmonically trapped one-dimensional (1D) Bose gas in the quasicondensate
regime using a finite-temperature classical field approach. By characterising
the oscillations via the dynamics of the density profile's rms width over long
time, we find that the rms width displays beating of two distinct frequencies.
This means that 1D Bose gas oscillates not at a single breathing mode
frequency, as found in previous studies, but as a superposition of two distinct
breathing modes, one oscillating at frequency close to $\simeq\!\sqrt{3}\omega$
and the other at $\simeq\!2\omega$, where $\omega$ is the trap frequency. The
breathing mode at $\sim\!\sqrt{3}\omega$ dominates the beating at lower
temperatures, deep in the quasicondensate regime, and can be attributed to the
oscillations of the bulk of the density distribution comprised of particles
populating low-energy, highly-occupied states. The breathing mode at
$\simeq\!2\omega$, on the other hand, dominates the beating at higher
temperatures, close to the nearly ideal, degenerate Bose gas regime, and is
attributed to the oscillations of the tails of the density distribution
comprised of thermal particles in higher energy states. The two breathing modes
have distinct damping rates, with the damping rate of the bulk component being
approximately four times larger than that of the tails component.",2207.00209v2
2022-07-29,Coordinated control in multi-terminal VSC-HVDC systems to improve transient stability: Impact on electromechanical-oscillation damping,"Multi-terminal high-voltage Direct Current technology based on Voltage-Source
Converter stations (VSC-MTDC) is expected to be one of the most important
contributors to the future of electric power systems. In fact, among other
features, it has already been shown how this technology can contribute to
improve transient stability in power systems by the use of supplementary
controllers. Along this line, this paper will investigate in detail how these
supplementary controllers may affect electromechanical oscillations, by means
of small-signal stability analysis. The paper analyses two control strategies
based on the modulation of active-power injections (P-WAF) and reactive-power
injections (Q-WAF) in the VSC stations. Both control strategies use global
signals of the frequencies of the VSC-MTDC system and they presented
significant improvements on transient stability. The paper will provide
guidelines for the design of these type of controllers to improve both, large-
and small-disturbance angle stability. Small-signal stability techniques (in
Matlab) will be used to assess electromechanical-oscillation damping, while
non-linear time domain simulation (in PSS/E) will be used to confirm the
results. Results will be illustrated in Nordic32A test system with an embedded
VSC-MTDC system. The paper analyses the impact of the controller gains and
communication latency on electromechanical-oscillation damping. The main
conclusion of the paper is that transient-stability-tailored supplementary
controllers in VSC-MTDC systems can be tuned to damp inter-area oscillations
too, maintaining their effectiveness for transient-stability improvement.",2208.00083v1
2022-08-04,Thermoelastic Damping in MEMS Gyroscopes at High Frequencies,"Microelectromechanical systems (MEMS) gyroscopes are widely used, e.g. in
modern automotive and consumer applications, and require signal stability and
accuracy in rather harsh environmental conditions. In many use cases, device
reliability must be guaranteed under large external loads at high frequencies.
The sensitivity of the sensor to such external loads depends strongly on the
damping, or rather quality factor, of the high frequency mechanical modes of
the structure. In this paper, we investigate the influence of thermoelastic
damping on several high frequency modes by comparing finite element simulations
with measurements of the quality factor in an application-relevant temperature
range. We measure the quality factors over different temperatures in vacuum, to
extract the relevant thermoelastic material parameters of the polycrystalline
MEMS device. Our simulation results show a good agreement with the measured
quantities, therefore proving the applicability of our method for predictive
purposes in the MEMS design process. Overall, we are able to uniquely identify
the thermoelastic effects and show their significance for the damping of the
high frequency modes of an industrial MEMS gyroscope. Our approach is generic
and therefore easily applicable to any mechanical structure with many possible
applications in nano- and micromechanical systems.",2208.02591v2
2022-08-02,Motion of a parametrically driven damped coplanar double pendulum,"We present the results of linear stability of a damped coplanar double
pendulum and its non-linear motion, when the point of suspension is vibrated
sinusoidally in the vertical direction with amplitude $a$ and frequency $\omega
$. A double pendulum has two pairs of Floquet multipliers, which have been
calculated for various driving parameters. We have considered the stability of
a double pendulum when it is in any of its possible stationary states: (i) both
pendulums are either vertically downward or upward and (ii) one pendulum is
downward, and the other is upward. The damping is considered to be
velocity-dependent, and the driving frequency is taken in a wide range. A
double pendulum excited from its stable state shows both periodic and chaotic
motion. The periodic motion about its pivot may be either oscillatory or
rotational. The periodic swings of a driven double pendulum may be either
harmonic or subharmonic for lower values of $a$. The limit cycles corresponding
to the normal mode oscillations of a double pendulum of two equal masses are
squeezed into a line in its configuration space. For unequal masses, the
pendulum shows multi-period swings for smaller values of $a$ and damping, while
chaotic swings or rotational motion at relatively higher values of $a$. The
parametric driving may lead to stabilization of a partially or fully inverted
double pendulum.",2208.03292v2
2022-08-09,Simultaneous measurements of unstable and stable Alfvén Eigenmodes in JET,"In this paper, we report the novel experimental observation of both unstable
and stable Toroidicity-induced Alfv\'en Eigenmodes (TAEs) measured
simultaneously in a JET tokamak plasma. The three-ion-heating scheme
(D-DNBI-3He) is employed to accelerate deuterons to MeV energies, thereby
destabilizing TAEs with toroidal mode numbers n = 3-5, each decreasing in mode
amplitude. At the same time, the Alfv\'en Eigenmode Active Diagnostic
resonantly excites a stable n = 6 TAE with total normalized damping rate
$-\gamma/\omega_0 \approx$ 1%-4%. Hybrid kinetic-MHD modeling with codes NOVA-K
and MEGA both find eigenmodes with similar frequencies, mode structures, and
radial locations as in experiment. NOVA-K demonstrates good agreement with the
n = 3, 4, and 6 TAEs, matching the damping rate of the n = 6 mode within
uncertainties and identifying radiative damping as the dominant contribution.
Improved agreement is found with MEGA for all modes: the unstable n = 3-5 and
stable n = 2, 6 modes, with the latter two stabilized by higher intrinsic
damping and lower fast ion drive, respectively. While some discrepancies remain
to be resolved, this unique validation effort gives us confidence in TAE
stability predictions for future fusion devices.",2208.05052v1
2022-09-24,Deep Attentive Belief Propagation: Integrating Reasoning and Learning for Solving Constraint Optimization Problems,"Belief Propagation (BP) is an important message-passing algorithm for various
reasoning tasks over graphical models, including solving the Constraint
Optimization Problems (COPs). It has been shown that BP can achieve
state-of-the-art performance on various benchmarks by mixing old and new
messages before sending the new one, i.e., damping. However, existing methods
of tuning a static damping factor for BP not only are laborious but also harm
their performance. Moreover, existing BP algorithms treat each variable node's
neighbors equally when composing a new message, which also limits their
exploration ability. To address these issues, we seamlessly integrate BP, Gated
Recurrent Units (GRUs), and Graph Attention Networks (GATs) within the
message-passing framework to reason about dynamic weights and damping factors
for composing new BP messages. Our model, Deep Attentive Belief Propagation
(DABP), takes the factor graph and the BP messages in each iteration as the
input and infers the optimal weights and damping factors through GRUs and GATs,
followed by a multi-head attention layer. Furthermore, unlike existing
neural-based BP variants, we propose a novel self-supervised learning algorithm
for DABP with a smoothed solution cost, which does not require expensive
training labels and also avoids the common out-of-distribution issue through
efficient online learning. Extensive experiments show that our model
significantly outperforms state-of-the-art baselines.",2209.12000v1
2022-12-01,Slack-based tunable damping leads to a trade-off between robustness and efficiency in legged locomotion,"Animals run robustly in diverse terrain. This locomotion robustness is
puzzling because axon conduction velocity is limited to a few ten meters per
second. If reflex loops deliver sensory information with significant delays,
one would expect a destabilizing effect on sensorimotor control. Hence, an
alternative explanation describes a hierarchical structure of low-level
adaptive mechanics and high-level sensorimotor control to help mitigate the
effects of transmission delays. Motivated by the concept of an adaptive
mechanism triggering an immediate response, we developed a tunable physical
damper system. Our mechanism combines a tendon with adjustable slackness
connected to a physical damper. The slack damper allows adjustment of damping
force, onset timing, effective stroke, and energy dissipation. We characterize
the slack damper mechanism mounted to a legged robot controlled in open-loop
mode. The robot hops vertically and planar over varying terrains and
perturbations. During forward hopping, slack-based damping improves faster
perturbation recovery (up to 170%) at higher energetic cost (27%). The tunable
slack mechanism auto-engages the damper during perturbations, leading to a
perturbation-trigger damping, improving robustness at minimum energetic cost.
With the results from the slack damper mechanism, we propose a new functional
interpretation of animals' redundant muscle tendons as tunable dampers.",2212.00475v1
2022-12-22,Spin wave dispersion of ultra-low damping hematite ($α\text{-Fe}_2\text{O}_3$) at GHz frequencies,"Low magnetic damping and high group velocity of spin waves (SWs) or magnons
are two crucial parameters for functional magnonic devices. Magnonics research
on signal processing and wave-based computation at GHz frequencies focussed on
the artificial ferrimagnetic garnet Y$_3$Fe$_5$O$_{12}$ (YIG) so far. We report
on spin-wave spectroscopy studies performed on the natural mineral hematite
($\alpha\text{-Fe}_2\text{O}_3$) which is a canted antiferromagnet. By means of
broadband GHz spectroscopy and inelastic light scattering, we determine a
damping coefficient of $1.1\times10^{-5}$ and magnon group velocities of a few
10 km/s, respectively, at room temperature. Covering a large regime of wave
vectors up to $k\approx 24~{\rm rad}/\mu$m, we find the exchange stiffness
length to be relatively short and only about 1 \r{A}. In a small magnetic field
of 30 mT, the decay length of SWs is estimated to be 1.1 cm similar to the best
YIG. Still, inelastic light scattering provides surprisingly broad and partly
asymmetric resonance peaks. Their characteristic shape is induced by the large
group velocities, low damping and distribution of incident angles inside the
laser beam. Our results promote hematite as an alternative and sustainable
basis for magnonic devices with fast speeds and low losses based on a stable
natural mineral.",2212.11887v2
2023-01-19,Magnetoreological spring as element of vibration control system of dynamicly active equipment for biofuel production,"The development of vibration protection systems that ensure efficiency and
safety in the operation of process equipment and pipelines is one of the main
tasks of controlling the dynamic state of machines. One of the effective
methods of vibration isolation of the equipment of these installations is the
use of vibration mounts. Today, both passive and active methods of
extinguishing are actively used. The combination of two methods of damping will
ensure the stability and adaptability of vibration protection systems to the
operating conditions of process equipment. The paper presents and investigates
the device of a hybrid vibration support, including a magnetorheological
spring, as an element of vibration damping. A distinctive feature of the
vibration mount is an extended range of performance and reduced wear rate of
the components. An analysis of the damping characteristics of a hybrid
vibration support in passive and active modes of operation is presented. A
simulation model of the vibration support under consideration has been
developed in the MATLAB Simulink simulation environment using the PIB
controller. The simulation results indicate the effectiveness of the use of
vibration damping systems with a magnetorheological spring in conjunction with
various technological equipment.",2301.07911v1
2023-01-30,Investigation of Ultrafast Demagnetization and Gilbert Damping and their Correlation in Different Ferromagnetic Thin Films Grown Under Identical Conditions,"Following the demonstration of laser-induced ultrafast demagnetization in
ferromagnetic nickel, several theoretical and phenomenological propositions
have sought to uncover its underlying physics. In this work we revisit the
three temperature model (3TM) and the microscopic three temperature model
(M3TM) to perform a comparative analysis of ultrafast demagnetization in
20-nm-thick cobalt, nickel and permalloy thin films measured using an
all-optical pump-probe technique. In addition to the ultrafast dynamics at the
femtosecond timescales, the nanosecond magnetization precession and damping are
recorded at various pump excitation fluences revealing a fluence-dependent
enhancement in both the demagnetization times and the damping factors. We
confirm that the Curie temperature to magnetic moment ratio of a given system
acts as a figure of merit for the demagnetization time, while the
demagnetization times and damping factors show an apparent sensitivity to the
density of states at the Fermi level for a given system. Further, from
numerical simulations of the ultrafast demagnetization based on both the 3TM
and the M3TM, we extract the reservoir coupling parameters that best reproduce
the experimental data and estimate the value of the spin flip scattering
probability for each system. We discuss how the fluence-dependence of
inter-reservoir coupling parameters so extracted may reflect a role played by
nonthermal electrons in the magnetization dynamics at low laser fluences.",2301.12797v1
2023-02-19,Collective Quantum Approach to Surface Plasmon Resonance Effect,"In this research we present a theory of the surface plasmon resonance (SPR)
effect based on the dual length-scale driven damped collective quantum
oscillations of the spill-out electrons in plasmonic material surface. The
metallic electron excitations are modeled using the Hermitian effective
Schr\""{o}dinger-Poisson system, whereas, the spill-out electron excitations are
modeled via the damped non-Hermitian effective Schr\""{o}dinger-Poisson system
adapted appropriately at the metal-vacuum interface. It is shows that, when
driven by external field, the system behaves like the driven damped oscillator
in wavenumber domain, quite analogous to the driven damped mechanical
oscillation in frequency domain, leading to the collective surface spill-out
electron excitation resonance. In this model the resonance occurs when the
wavenumber of the driving pseudoforce matches that of the surface plasmon
excitations which can be either due to single-electrons or collective effects.
Current theory of SPR is based on longitudinal electrostatic excitations of the
surface electrons, instead of the polariton excitation parallel to the
metal-dielectric or metal-vacuum surface. Current theory may also be extended
to use for the localized surface plasmon resonance (LSPR) in nanometer sized
metallic surfaces in non-planar geometry. A new equation of state (EoS) for the
plasmon electron number density in quantum plasmas is obtained which limits the
plasmonic effects in high-density low-temperature electron gas regime, due to
small transition probability of electrons to the plasmon energy band.",2302.13974v1
2023-03-01,Evolution of the eccentricity and inclination of low-mass planets subjected to thermal forces: a numerical study,"By means of three dimensional, high resolution hydrodynamical simulations we
study the orbital evolution of weakly eccentric or inclined low-mass
protoplanets embedded in gaseous discs subject to thermal diffusion. We
consider both non-luminous planets, and planets that also experience the
radiative feedback from their own luminosity. We compare our results to
previous analytical work, and find that thermal forces (the contribution to the
disc's force arising from thermal effects) match those predicted by linear
theory within $\sim 20$%. When the planet's luminosity exceeds a threshold
found to be within $10$% of that predicted by linear theory, its eccentricity
and inclination grow exponentially, whereas these quantities undergo a strong
damping below this threshold. In this regime of low luminosity indeed, thermal
diffusion cools the surroundings of the planet and allows gas to accumulate in
its vicinity. It is the dynamics of this gas excess that contributes to damp
eccentricity and inclination. The damping rates obtained can be up to $h^{-1}$
times larger than those due to the resonant interaction with the disc, where
$h$ is the disc's aspect ratio. This suggests that models that incorporate
planet-disc interactions using well-known formulae based on resonant
wave-launching to describe the evolution of eccentricity and inclination
underestimate the damping action of the disc on the eccentricity and
inclination of low-mass planets by an order of magnitude.",2303.00867v1
2023-03-13,Discriminative sEMG-based features to assess damping ability and interpret activation patterns in lower-limb muscles of ACLR athletes,"Objective: The main goal of the athletes who undergo anterior cruciate
ligament reconstruction (ACLR) surgery is a successful return-to-sport. At this
stage, identifying muscular deficits becomes important. Hence, in this study,
three discriminative features based on surface electromyographic signals (sEMG)
acquired in a dynamic protocol are introduced to assess the damping ability and
interpret activation patterns in lower-limb muscles of ACLR athletes. Methods:
The features include the median frequency of the power spectrum density (PSD),
the relative percentage of the equivalent damping or equivalent stiffness
derived from the median frequency, and the energy of the signals in the
time-frequency plane of the pseudo-Wigner-Ville distribution (PWVD). To
evaluate the features, 11 healthy and 11 ACLR athletes (6 months
post-reconstruction surgery) were recruited to acquire the sEMG signals from
the medial and the lateral parts of the hamstrings, quadriceps, and
gastrocnemius muscles in pre- and post-fatigue single-leg landings. Results: A
significant damping deficiency is observed in the hamstring muscles of ACLR
athletes by evaluating the proposed features. This deficiency indicates that
more attention should be paid to this muscle of ACLR athletes in
pre-return-to-sport rehabilitations. Conclusion: The quality of
electromyography-based pre-return-to-sport assessments on ACLR subjects depends
on the sEMG acquisition protocol, as well as the type and nature of the
extracted features. Hence, combinatorial application of both energy-based
features (derived from the PWVD) and power-based features (derived from the
PSD) could facilitate the assessment process by providing additional
biomechanical information regarding the behavior of the muscles surrounding the
knee.",2303.06954v1
2023-03-28,Search for damped oscillating structures from charged pion electromagnetic form factor data,"The damped oscillating structures recently revealed by a three parametric
formula from the proton ``effective'' form factor data extracted of the
measured total cross section $\sigma^{bare}_{tot}(e^+e^-\to p\bar p)$ still
seem to have an unknown origin. The conjectures of their direct manifestation
of the quark-gluon structure of the proton indicate that they are not specific
only of the proton and neutron, but they have to be one's own, similar to other
hadrons.
  Therefore, the oscillatory structures from the charged pion electromagnetic
form factor timelike data, extracted of the process $e^+e^-\to \pi^+ \pi^-$ are
investigated by using the same procedure as in the case of the proton.
  The analysis shows the appearance of the oscillating structures in the
description of the charged pion electromagnetic form factor timelike data by
three parametric formula with a rather large value of $\chi^2/ndf$, while the
description of the data by the physically well-founded Unitary and Analytic
model has not revealed any damped oscillating structures.
  From the obtained result on the most simple object of strong interactions,
one can conclude that damped oscillating structures received from the
``effective'' proton form factor data are probably generated by a utilization
of the improper three parametric formula which does not describe these data
with sufficient precision.",2303.16681v1
2023-05-15,Landau damping and the survival threshold,"In this paper, we establish the large time asymptotic behavior of solutions
to the linearized Vlasov-Poisson system near general spatially homogenous
equilibria $\mu(\frac12|v|^2)$ with connected support on the whole space
$\RR^3_x \times \RR^3_v$, including those that are non-monotone. The problem
can be solved completely mode by mode for each spatial wave number, and their
longtime dynamics is intimately tied to the ``survival threshold'' of wave
numbers computed by $$\kappa_0^2 = 4\pi \int_0^\Upsilon \frac{u^2\mu(\frac12
u^2)}{\Upsilon^2-u^2} \;du$$ where $\Upsilon$ is the maximal speed of particle
velocities. It is shown that purely oscillatory electric fields exist and obey
a Klein-Gordon's type dispersion relation for wave numbers below the threshold,
thus confirming the existence of Langmuir's oscillatory waves known in the
physical literature. At the threshold, the phase velocity of these oscillatory
waves enters the range of admissible particle velocities, namely there are
particles that move at the same propagation speed of the waves. It is this
exact resonant interaction between particles and the oscillatory fields that
causes the waves to be damped, classically known as Landau damping. Landau's
law of decay is explicitly computed and is sensitive to the decaying rate of
the background equilibria. The faster it decays at the maximal velocity, the
weaker Landau damping is. Beyond the threshold, the electric fields are a
perturbation of those generated by the free transport dynamics and thus decay
rapidly fast due to the phase mixing mechanism.",2305.08672v1
2023-06-04,Large Dynamical Tide Amplitudes from Small Kicks at Pericenter,"The effect of dynamical tide ``kicks"" on eccentric binary orbits is
considered using the orbital mapping method. It is demonstrated that when mode
damping is negligible the mode amplitude will generically grow in time for all
values of orbital eccentricity and semi-major axis, even for small kicks
outside the regime exhibiting diffusive growth. The origin of the small-kick
growth is the change in kick size from orbit to orbit, an effect quadratic in
the mode amplitude. When damping of the mode is included, the growth is shut
off when the damping time is shorter than the growth time. Hence, in practice,
kicks of sufficient size and long mode damping times are required for
interesting levels of growth to occur. Application to the circularization of
hot Jupiters is discussed. Previous investigations found that diffusive growth
of the planetary f-mode in the large-kick regime would lead to rapid orbital
shrinkage, but upon exiting the diffusive regime at $e \sim 0.9$ the theory
would predict a large population of highly eccentric orbits. Simulations
presented here show that subsequent orbital evolution relying on the small-kick
regime may further decrease the eccentricity to $e \sim 0.2$ on timescales much
less than the Gyrs ages of these systems.",2306.02382v1
2023-06-16,Damping of MHD Turbulence in A Partially Ionized Medium,"The coupling state between ions and neutrals in the interstellar medium plays
a key role in the dynamics of magnetohydrodynamic (MHD) turbulence, but is
challenging to study numerically. In this work, we investigate the damping of
MHD turbulence in a partially ionized medium using 3D two-fluid (ions+neutrals)
simulations generated with the AthenaK code. Specifically, we examine the
velocity, density, and magnetic field statistics of the two-fluid MHD
turbulence in different regimes of neutral-ion coupling. Our results
demonstrate that when ions and neutrals are strongly coupled, the velocity
statistics resemble those of single-fluid MHD turbulence. Both the velocity
structures and kinetic energy spectra of ions and neutrals are similar, while
their density structures can be significantly different. With an excess of
small-scale sharp density fluctuations in ions, the density spectrum in ions is
shallower than that of neutrals. When ions and neutrals are weakly coupled, the
turbulence in ions is more severely damped due to the ion-neutral collisional
friction than that in neutrals, resulting in a steep kinetic energy spectrum
and density spectrum in ions compared to the Kolmogorov spectrum. We also find
that the magnetic energy spectrum basically follows the shape of the kinetic
energy spectrum of ions, irrespective of the coupling regime. In addition, we
find large density fluctuations in ions and neutrals and thus spatially
inhomogeneous ionization fractions. As a result, the neutral-ion decoupling and
damping of MHD turbulence take place over a range of length scales.",2306.10010v2
2023-07-24,BGO quenching effect on spectral measurements of cosmic-ray nuclei in DAMPE experiment,"The Dark Matter Particle Explorer (DAMPE) is a satellite-borne detector
designed to measure high energy cosmic-rays and $\gamma$-rays. As a key
sub-detector of DAMPE, the Bismuth Germanium Oxide (BGO) imaging calorimeter is
utilized to measure the particle energy with a high resolution. The nonlinear
fluorescence response of BGO for large ionization energy deposition, known as
the quenching effect, results in an under-estimate of the energy measurement
for cosmic-ray nuclei. In this paper, various models are employed to
characterize the BGO quenching factors obtained from the experimental data of
DAMPE. Applying the proper quenching model in the detector simulation process,
we investigate the tuned energy responses for various nuclei and compare the
results based on two different simulation softwares, i.e. GEANT4 and FLUKA. The
BGO quenching effect results in a decrease of the measured energy by
approximately $2.5\%$ ($5.7 \%$) for carbon (iron) at $\sim$10 GeV/n and $<1\%$
above 1 TeV/n, respectively. Accordingly, the correction of the BGO quenching
effect leads to an increase of the low-energy flux measurement of cosmic-ray
nuclei.",2307.12629v1
2023-08-04,"Interplay of space charge, intrabeam scattering and synchrotron radiation in the Compact Linear Collider damping rings","Future ultra-low emittance rings for electron/positron colliders requiring
extremely high beam brightness can be limited by collective effects. In this
paper, the interplay of effects such as synchrotron radiation, intra-beam
scattering (IBS) and space charge in the vicinity of excited betatron
resonances is assessed. In this respect, two algorithms were developed to
simulate IBS and synchrotron radiation effects and integrated in the PyORBIT
tracking code, to be combined with its widely used space charge module. The
impact of these effects on the achievable beam parameters of the Compact Linear
Collider (CLIC) Damping Rings was studied, showing that synchrotron radiation
damping mitigates the adverse effects of IBS and space charge induced resonance
crossing. The studies include also a full dynamic simulation of the CLIC
damping ring cycle starting from the injection beam parameters. It is
demonstrated that a careful working point choice is necessary, in order to
accommodate the transition from a non-linear lattice induced detuning to a
space-charge dominated one and thereby avoid excessive losses and emittance
growth generated in the vicinity of strong resonances.",2308.02196v3
2023-08-04,Nonlinear wave damping by Kelvin-Helmholtz instability induced turbulence,"Magnetohydrodynamic kink waves naturally form as a consequence of
perturbations to a structured medium, for example transverse oscillations of
coronal loops. Linear theory has provided many insights in the evolution of
linear oscillations, and results from these models are often applied to infer
information about the solar corona from observed wave periods and damping
times. However, simulations show that nonlinear kink waves can host the
Kelvin-Helmholtz instability (KHi) which subsequently creates turbulence in the
loop, dynamics which are beyond linear models. In this paper we investigate the
evolution of KHi-induced turbulence on the surface of a flux tube where a
non-linear fundamental kink-mode has been excited. We control our numerical
experiment so that we induce the KHi without exciting resonant absorption. We
find two stages in the KHi turbulence dynamics. In the first stage, we show
that the classic model of a KHi turbulent layer growing $\propto t$is
applicable. We adapt this model to make accurate predictions for damping of the
oscillation and turbulent heating as a consequence of the KHi dynamics. In the
second stage, the now dominant turbulent motions are undergoing decay. We find
that the classic model of energy decay proportional to $t^{-2}$ approximately
holds and provides an accurate prediction of the heating in this phase. Our
results show that we can develop simple models for the turbulent evolution of a
non-linear kink wave, but the damping profiles produced are distinct from those
of linear theory that are commonly used to confront theory and observations.",2308.02217v2
2023-08-10,JWST observations of galaxy damping wings during reionization interpreted with cosmological simulations,"Spectra of the highest redshift galaxies taken with JWST are now allowing us
to see into the heart of the reionization epoch. Many of these observed
galaxies exhibit strong damping wing absorption redward of their Lyman-$\alpha$
emission. These observations have been used to measure the redshift evolution
of the neutral fraction of the intergalactic medium and sizes of ionized
bubbles. However, these estimates have been made using a simple analytic model
for the intergalactic damping wing. We explore the recent observations with
models of inhomogeneous reionization from the Sherwood-Relics simulation suite.
We carry out a comparison between the damping wings calculated from the
simulations and from the analytic model. We find that although the agreement is
good on the red side of the Lyman-$\alpha$ emission, there is a discrepancy on
the blue side due to residual neutral hydrogen present in the simulations,
which saturates the intergalactic absorption. For this reason, we find that it
is difficult to reproduce the claimed observations of large bubble sizes at z ~
7, which are driven by a detection of transmitted flux blueward of the
Lyman-$\alpha$ emission. We suggest instead that the observations can be
explained by a model with smaller ionized bubbles and larger intrinsic
Lyman-$\alpha$ emission from the host galaxy.",2308.05800v1
2023-08-23,Dynamics of pinned quantized vortices in superfluid $^4$He in a microelectromechanical oscillator,"We numerically studied the vortex dynamics at zero temperature in superfluid
$^4$He confined between two parallel rough solid boundaries, one of which
oscillates in a shear mode. This study was motivated by the experimental work
by Barquist $et$ $al.$ which employed a microelectromechanical systems (MEMS)
oscillator operating in superfluid $^4$He at a near-zero temperature. Their
experiments suggest that the motion of the MEMS oscillator is damped by
quantized vortices. In our study, we postulated that this damping effect was
closely associated with vortex pinning phenomena and developed pinning models.
Our primary objective is to understand the vortex dynamics in the presence of
pinning and to provide insight into the experimental observations regarding the
damping mechanism. We confirmed that Kelvin waves were excited in the pinned
vortices when the oscillation frequency of the solid boundary matched with the
mode frequency of the Kelvin wave. Additionally, we examined the formation and
evolution of vortex tangles between the boundaries. The vortex tangle was
suppressed in the presence of pinning, while the absence of pinning allowed to
form well developed vortex tangle resulting in turbulence. Finally, by
evaluating the tension of pinned vortices we extracted the damping force acting
on the solid boundaries.",2308.11942v2
2023-12-29,Modeling polyelectrolyte hydration from a multi scale polarizable pseudo particle solvent coarse grained approach,"We investigate the reliability of simulations of polyelectrolyte systems in
aqueous environments, simulations that are performed using an efficient multi
scale coarse grained polarizable pseudo-particle particle approach, denoted as
pppl, to model the solvent water, whereas the solutes are modeled using a
polarizable all atom force field. We focus our study on issues tied to two key
parameters of the pppl approach, namely the extension of the solvent domain SD
at the close vicinity of a solute (domain in which each solvent particle
corresponds to a single water molecule) and the magnitude of solute/solvent
short range polarization damping effects. To this end we built a new pppl
models from which we simulate NaCl aqueous solutions at the molar concentration
scale. We also re investigate the hydration of a hydrophobic polyelectrolyte
polymer that we showed in an earlier study [J Chem Phys, 114903 (155) 2021] to
evolve towards a counter intuitive globular form surrounded by a spherical
counter ion cloud along pppl-based simulations. Strong short range damping is
pivotal to simulate NaCl aqueous solutions. The extension of the domain SD (as
well as short range damping) has a weak effect on the conformation of the
polymer, but it plays a pivotal role to compute accurate solute/solvent
interaction energies. In all our results lead us to recommend to simulate
polyelectrolyte polymers as dissolved alone in pppl fluids (i.e. without
explicitly accounting for their counter ions) to investigate their behavior at
infinite dilution conditions, and to systematically consider strong
solute/solvent polarization short range damping to model charged species.",2312.17580v1
2024-02-19,Global existence for non-homogeneous incompressible inviscid fluids in presence of Ekman pumping,"In this paper, we study the global solvability of the density-dependent
incompressible Euler equations, supplemented with a damping term of the form $
\mathfrak{D}_{\alpha}^{\gamma}(\rho, u) = \alpha \rho^{\gamma} u $, where
$\alpha>0$ and $ \gamma \in \{0,1\} $. To some extent, this system can be seen
as a simplified model describing the mean dynamics in the ocean; from this
perspective, the damping term can be interpreted as a term encoding the effects
of the celebrated Ekman pumping in the system.
  On the one hand, in the general case of space dimension $d\geq 2$, we
establish global well-posedness in the Besov spaces framework, under a
non-linear smallness condition involving the size of the initial velocity field
$u_0$, of the initial non-homogeneity $\rho_0-1$ and of the damping coefficient
$\alpha$. On the other hand, in the specific situation of planar motions and
damping term with $\gamma=1$, we exhibit a second smallness condition implying
global existence, which in particular yields global well-posedness for
arbitrarily large initial velocity fields, provided the initial density
variations $\rho_0-1$ are small enough. The formulated smallness conditions
rely only on the endpoint Besov norm $B^1_{\infty,1}$ of the initial datum,
whereas, as a byproduct of our analysis, we derive exponential decay of the
velocity field and of the pressure gradient in the high regularity norms
$B^s_{p,r}$.",2402.12592v1
2024-02-20,The Fundamental Parameters of Astrophysical Plasma Turbulence and its Dissipation: Nonrelativistic Limit,"A specific set of dimensionless plasma and turbulence parameters is
introduced to characterize the nature of turbulence and its dissipation in
weakly collisional space and astrophysical plasmas. Key considerations are
discussed for the development of predictive models of the turbulent plasma
heating that characterize the partitioning of dissipated turbulent energy
between the ion and electron species and between the perpendicular and parallel
degrees of freedom for each species. Identifying the kinetic physical
mechanisms that govern the damping of the turbulent fluctuations is a critical
first step in constructing such turbulent heating models. A set of ten general
plasma and turbulence parameters are defined, and reasonable approximations
along with the exploitation of existing scaling theories for
magnetohydrodynamic turbulence are used to reduce this general set of ten
parameters to just three parameters in the isotropic temperature case. A
critical step forward in this study is to identify the dependence of all of the
proposed kinetic mechanisms for turbulent damping in terms of the same set of
fundamental plasma and turbulence parameters. Analytical estimations of the
scaling of each damping mechanism on these fundamental parameters are
presented, and this information is synthesized to produce the first phase
diagram for the turbulent damping mechanisms as a function of driving scale and
ion plasma beta.",2402.12829v1
2024-03-06,Universality of pseudo-Goldstone damping near critical points,"Recently, in studies of holographic models and hydrodynamics with spontaneous
breaking of approximate symmetries, it has been proposed that the damping of
pseudo-Goldstone modes at finite temperatures is universally constrained in the
way that $\Omega_{\varphi}/m_{\varphi}^2\simeq D_{\varphi}$ in the broken
phase, where $\Omega_{\varphi}$ and $m_{\varphi} $ are the relaxation rate at
zero wavenumber and the mass of pseudo-Goldstones, $D_{\varphi}$ is the
Goldstone diffusivity in the limit of purely spontaneous breaking. In this
paper, we investigate the pseudo-Goldstone damping in a purely relaxational
O($N$) model by performing the functional renormalization group calculations at
the full quantum and stochastic level within the Schwinger-Keldysh formalism.
We find that, away from the critical temperature, the proposed relation is
always valid. When the temperature is very close to the critical value such
that the mass of the Higgs mode is comparable to the mass of the
pseudo-Goldstone modes, the pseudo-Goldstone damping displays a novel scaling
behavior that follows $\Omega_\varphi/m_\varphi^2\propto
m_{\varphi}^{\Delta_\eta}$ with a correction $\Delta_\eta$ controlled by the
critical universalities. Moreover, we study how the correction depends on the
value of $N$ and show that $\Delta_\eta \rightarrow 0$ when fluctuations are
infinitely suppressed in the large $N$ limit. In this case, the proposed
relation works even in the critical region. Finally, we match our results to
the dissipative sector of the pion dynamics near the chiral phase transition.",2403.03503v2
1993-11-17,Early Reionization in Cosmology,"The cosmic microwave background (CMB) anisotropies have turned out to
represent one of the most stringent 'bottle necks' for scenarios of large scale
structure formation. As a possibility to relax this constraint, it has been
proposed that early reionization can damp CMB fluctuations on small scales due
to photon diffusion in the ionized plasma. As an example, I investigate the
recently proposed scenario with cold dark matter (CDM) and texture seeds.
There, an analysis of CMB anisotropies shows that early reionization is a
crucial ingredient for this scenario. Without damping, the small scale
anisotropies would dominate and exceed observed limits. In this paper I present
analytical and numerical results for the amount of damping due to early
reionization for CMB perturbations induced by a collapsing texture.
Furthermore, the spectral distortion of the CMB due to Compton scattering of
the hotter plasma electrons is calculated. Next I discuss the physical
processes which lead to a system of coupled ordinary differential equations for
the degree of ionization, the electron temperature and the evolution of the
ionizing radiation.",9311039v1
1994-08-18,The Damping and Excitation of Galactic Warps by Dynamical Friction,"We investigate the dynamical interaction of galactic warps with the
surrounding dark matter halo, using analytic perturbation theory. A precessing
warp induces a density wake in the collisionless dark matter, which acts back
on the original warp, transferring energy and angular momentum between the warp
and halo (dynamical friction). In most cases dynamical friction damps the warp,
but in unusual circumstances (such as a halo that rotates in the same direction
as the precession of the warp, or a warp in the equatorial plane of an
axisymmetric prolate halo) friction can excite a warp. The damping/excitation
time is usually short compared to the Hubble time for realistic systems. Thus
most warps cannot be primordial; they must be maintained by some ongoing
excitation mechanism.",9408068v1
1995-09-14,Another Look at Gaussian Isocurvature Hot Dark Matter Models For Large- Scale Structure,"We examine Gaussian isocurvature hot dark matter (massive neutrino) models
for large-scale structure in which the initial density perturbations are
produced in the baryons with a power--law spectrum $P_B(k) = Ak^{n_B}$. We
calculate the linearly-evolved power spectrum and cosmic microwave
fluctuations. We find that models with only isocurvature perturbations are
inconsistent with observations of damped Ly$\alpha$ systems and COBE
constraints on the power index. However, models which contain a mixture of
adiabatic and isocurvature perturbations can be made consistent with COBE,
galaxy surveys and damped Ly$\alpha$ systems.Isocurvature hot dark matter
models also produce a bias between baryons and neutrinos even in the linear
regime. We find that this ``natural bias'' can increase the baryon fraction in
small scale objects like damped Ly$\alpha$ systems, but it has no effect on
cluster scales.",9509075v1
1995-10-16,Star Formation and Chemical Evolution in Damped Lya Clouds,"Using the redshift evolution of the neutral hydrogen density, as inferred
from observations of damped Ly$\alpha$ clouds, we calculate the evolution of
star formation rates and elemental abundances in the universe. For most
observables our calculations are in rough agreement with previous results based
on the instantaneous re-cycling approximation (IRA). However, for the key
metallicity tracer Zn, we find a better match to the observed abundance at high
redshift than that given by the constant-yield IRA model. We investigate
whether the redshift evolution of deuterium, depressions in the diffuse
extragalactic gamma-ray background, and measurement of the MeV neutrino
background may help determine if observational bias due to dust obscuration is
important. We also indicate how the importance of dust on the calculations can
be significantly reduced if correlations of the HI column density with
metallicity are present. The possibilities for measuring $q_o$ with
observations of elemental abundances in damped Ly$\alpha$ systems are
discussed.",9510078v1
1995-12-12,A radio Search for high redshift HI absorption,"Ground based optical observations have yielded considerable information on
the statistics of damped-lyman alpha systems. In particular these systems are
known to be the dominant repository of the observed neutral gas at high
redshift. However, particularly at high redshift, there is the possibility that
optical observations could be biased due to the exclusion of damped-lyman alpha
systems that contain moderate to significant amounts of dust. Independent
observational constraints on the neutral hydrogen content at high redshifts and
the amount of dust in high redshift systems can be obtained from a radio search
against the bright lobes of distant radio galaxies (which is less affected by
the presence of dust in foreground damped-lyman alpha systems). We describe
here a pilot radio survey along the line of sight to a small sample of high
redshift radio galaxies, and also present some preliminary results. The survey
uses a novel observing mode at the WSRT which enables one to make sensitive
searches of a large redshift interval in a modest amount of telescope time.",9512069v1
1996-01-26,The chemical evolution of galaxies at high redshift,"Observations of absorption lines in the spectra of distant QSOs offer a new
approach for tracking the evolution of normal galaxies from early epochs to the
present day. The damped Ly alpha systems are particularly suitable for
measuring the properties of what are likely to be the progenitors of
present-day luminous galaxies. We have recently concluded a long-term survey of
30 damped absorbers (including eight from the literature) aimed at measuring
the metallicity and dust content of the universe from redshift z = 3.39 to
0.69. The major conclusions are that the epoch of chemical enrichment in
galaxies may have begun at z = 2.5-3--corresponding to a look-back time of 14
Gyr--and that at z = 2 the typical metallicity was 1/15 of solar. There is
clear evidence for the presence of interstellar dust at z = 2, although several
high-redshift galaxies, particularly the most metal-poor, appear to be
essentially dust-free. We discuss the nature of the damped Ly alpha galaxies in
the light of these and other new results.",9601153v1
1996-07-23,A damped Ly-alpha candidate at z~0.1 toward Q 0439-433,"We report on the detection of a z_gal=0.101 galaxy projected on the sky at
4.2 arcsec (or 5.2 h^{-1} kpc for q_o=0.5) from the quasar Q 0439-433
(z_em=0.594). The HST spectrum of the quasar shows strong MgII, FeII, SiII,
AlII and CIV absorption lines at the same redshift as the galaxy. The
equivalent width ratios of the low ionization lines indicate that this system
is probably damped with a neutral hydrogen column density of
N_HI~10^{20}cm^{-2}. The CIV doublet presents a complex structure, and in
particular a satellite with a velocity v=1100km/s relative to the galaxy.
Additional HST and redshifted 21cm observations of this QSO-galaxy pair would
offer an ideal opportunity to study the morphology of a damped absorber and the
kinematics of the halo of a low-redshift galaxy.",9607111v2
1997-08-11,Dynamos with different formulations of a dynamic alpha-effect,"We investigate the behaviour of $\alpha\Omega$ dynamos with a dynamic
$\alpha$, whose evolution is governed by the imbalance between a driving and a
damping term. We focus on truncated versions of such dynamo models which are
often studied in connection with solar and stellar variability. Given the
approximate nature of such models, it is important to study how robust they are
with respect to reasonable changes in the formulation of the driving and
damping terms. For each case, we also study the effects of changes of the
dynamo number and its sign, the truncation order and initial conditions. Our
results show that changes in the formulation of the driving term have important
consequences for the dynamical behaviour of such systems, with the detailed
nature of these effects depending crucially on the form of the driving term
assumed, the value and the sign of the dynamo number and the initial
conditions. On the other hand, the change in the damping term considered here
seems to produce little qualitative effect.",9708093v1
1997-11-20,ORT observations of the damped Lyman alpha system towards PKS 0201+113,"We report a deep radio search with the Ooty Radio Telescope (ORT) for the
redshifted 21 cm absorption line from the damped Lyman alpha system seen at
redshift 3.388 against the quasar PKS 0201+113. This is currently the most
distant system for which a detection of 21 cm absorption has been claimed. The
present observations have a sensitivity comparable to the earlier ones and
detect no statistically significant absorption. We use the non-detection to
place an upper limit of ~ 0.011 on the optical depth of the damped Lyman alpha
absorber. This corresponds to a lower limit of ~ 5600 K to the spin temperature
of the system. This is considerably higher than the previous upper limit of ~
1380 K.",9711234v1
1998-01-28,Dynamical Tide in Solar-Type Binaries,"Circularization of late-type main-sequence binaries is usually attributed to
turbulent convection, while that of early-type binaries is explained by
resonant excitation of g modes. We show that the latter mechanism operates in
solar-type stars also and is at least as effective as convection, despite
inefficient damping of g modes in the radiative core. The maximum period at
which this mechanism can circularize a binary composed of solar-type stars in
10 Gyr is as low as 3 days, if the modes are damped by radiative diffusion only
and g-mode resonances are fixed; or as high as 6 days, if one allows for
evolution of the resonances and for nonlinear damping near inner turning
points. Even the larger theoretical period falls short of the observed
transition period by a factor two.",9801289v1
1998-02-06,Acoustic oscillations and viscosity,"Using a simple thermo-hydrodynamic model that respects relativistic
causality, we revisit the analysis of qualitative features of acoustic
oscillations in the photon-baryon fluid. The growing photon mean free path
introduces transient effects that can be modelled by the causal generalization
of relativistic Navier-Stokes-Fourier theory. Causal thermodynamics provides a
more satisfactory hydrodynamic approximation to kinetic theory than the
quasi-stationary (and non-causal) approximations arising from standard
thermodynamics or from expanding the photon distribution to first order in the
Thomson scattering time. The causal approach introduces small corrections to
the dispersion relation obtained in quasi-stationary treatments. A dissipative
contribution to the speed of sound slightly increases the frequency of the
oscillations. The diffusion damping scale is slightly increased by the causal
corrections. Thus quasi-stationary approximations tend to over-estimate the
spacing and under-estimate the damping of acoustic peaks. In our simple model,
the fractional corrections at decoupling are $\gtrsim 10^{-3}$.",9802074v2
2000-02-29,Metallicity Evolution in the Early Universe,"Observations of the damped Lya systems provide direct measurements on the
chemical enrichment history of neutral gas in the early universe. In this
Letter, we present new measurements for four damped Lya systems at high
redshift. Combining these data with [Fe/H] values culled from the literature,
we investigate the metallicity evolution of the universe from z~1.5-4.5.
Contrary to our expectations and the predictions of essentially every chemical
evolution model, the N(HI)-weighted mean [Fe/H] metallicity exhibits minimal
evolution over this epoch. For the individual systems, we report tentative
evidence for an evolution in the unweighted [Fe/H] mean and the scatter in
[Fe/H] with the higher redshift systems showing lower scatter and lower typical
[Fe/H] values. We also note that no damped Lya system has [Fe/H] < -2.7 dex.
Finally, we discuss the potential impact of small number statistics and dust on
our conclusions and consider the implications of these results on chemical
evolution in the early universe.",0002513v3
2000-06-02,Surveys for z > 3 Damped Lyman-alpha Absorption Systems,"We have completed spectroscopic observations using LRIS on the Keck 1
telescope of 30 very high redshift quasars, 11 selected for the presence of
damped Ly-alpha absorption systems and 19 with redshifts z > 3.5 not previously
surveyed for absorption systems. We have surveyed an additional 10 QSOs with
the Lick 120'' and the Anglo-Australian Telescope. We have combined these with
previous data resulting in a statistical sample of 646 QSOs and 85 damped
Ly-alpha absorbers with column densities N(HI) >= 2 x 10^20 atoms/cm^2 covering
the redshift range 0.008 <= z <= 4.694. To make the data in our statistical
sample more readily available for comparison with scenarios from various
cosmological models, we provide tables that includes all 646 QSOs from our new
survey and previously published surveys. They list the minimum and maximum
redshift defining the redshift path along each line of sight, the QSO emission
redshift, and when an absorber is detected, the absorption redshift and
measured HI column density. [see the paper for the complete abstract]",0006044v1
2000-06-21,Constraints on the physical properties of the damped Ly-alpha system of Q0000-2619 at z = 3.054,"We present the detection of CII and CII* absorption in the z = 3.0543 damped
Ly-alpha system toward Q0000-2619. The derived population ratio implies a fine
structure excitation temperature between 19.6 and 21.6 K. The upper value sets
a strict upper limit on the CMB temperature at this redshift, which is
consistent with the predicted value of 11.05 K from standard cosmology. Under
the assumptions of an ionization degree ranging from 0 to 10%, a gas kinetic
temperature between 100 and 10000 K and a UV field with a Milky Way spectrum,
the density of the absorber is constrained to be between 0.7 and 40 cm^-3 and
the H-ionizing flux between 1 and 80 times the intensity of the Galactic UV
field. If the damped Ly-alpha system is assumed to be homogeneous, the
implication is that its size in the direction of the line of sight must be
between 1 and 100 pc.",0006308v1
2001-04-10,Damping scales of neutralino cold dark matter,"The lightest supersymmetric particle, most likely the neutralino, might
account for a large fraction of dark matter in the Universe. We show that the
primordial spectrum of density fluctuations in neutralino cold dark matter
(CDM) has a sharp cut-off due to two damping mechanisms: collisional damping
during the kinetic decoupling of the neutralinos at about 30 MeV (for typical
neutralino and sfermion masses) and free streaming after last scattering of
neutralinos. The last scattering temperature is lower than the kinetic
decoupling temperature by one order of magnitude. The cut-off in the primordial
spectrum defines a minimal mass for CDM objects in hierarchical structure
formation. For typical neutralino and sfermion masses the first gravitationally
bound neutralino clouds have to have masses above 10^(-7) solar masses.",0104173v2
2002-05-15,Building the bridge between Damped Ly-alpha Absorbers and Lyman Break galaxies,"In 2000, we started the program ``Building the Bridge between Damped Ly-alpha
Absorbers and Lyman-Break Galaxies: Ly-alpha Selection of Galaxies'' at the
European Southern Observatory's Very Large Telescope. This project is an
attempt to use Ly-alpha selection of high-z galaxies to bridge the gap between
absorption- and emission-selected galaxies by creating a large database of z=3
galaxies belonging to the abundant population of faint (R>25.5) galaxies probed
by the Damped Ly-alpha Absorbers (DLAs). Here we present the first results of
our program, namely the results from a deep Ly-alpha study of the field of the
z=2.85 DLA towards Q2138-4427.",0205234v2
2002-05-23,Constraining the strength of Dark Matter Interactions from Structure Formation,"We discuss the damping of primordial dark matter fluctuations, taking into
account explicitly the interactions of dark matter - whatever their intensity -
both with itself and with other particle species. Relying on a general
classification of dark matter particle candidates, our analysis provides, from
structure formation, a new set of constraints on the dark matter particle mass
and interaction rates (in particular with photons and neutrinos).
  This determines up to which cross sections the dark matter interactions may
effectively be disregarded, and when they start playing an essential role,
either through collisional damping or through an enhancement of the
free-streaming scale. It leads us to extend the notions of Cold, Warm and Hot
Dark Matter scenarios when dark matter interactions are no longer taken to be
negligible. It also suggests the possibility of new scenarios of Collisional
Warm Dark Matter, with moderate damping induced by dark matter interactions.",0205406v1
2002-06-06,A catalogue of damped Lyman alpha absorption systems and radio flux densities of the background quasars,"We present a catalogue of the 322 damped Lyman alpha absorbers taken from the
literature. All damped Lyman alpha absorbers are included, with no selection on
redshift or quasar magnitude. Of these, 123 are candidates and await
confirmation using high resolution spectroscopy. For all 322 objects we
catalogue the radio properties of the background quasars, where known. Around
60 quasars have radio flux densities above 0.1 Jy and approximately half of
these have optical magnitudes brighter than V = 18. This compilation should
prove useful in several areas of extragalactic/cosmological research.",0206091v1
2002-11-14,Formation of small-scale structure in SUSY CDM,"The lightest supersymmetric particle, most likely the lightest neutralino, is
one of the most prominent particle candidates for cold dark matter (CDM). We
show that the primordial spectrum of density fluctuations in neutralino CDM has
a sharp cut-off, induced by two different damping mechanisms. During the
kinetic decoupling of neutralinos, non-equilibrium processes constitute
viscosity effects, which damp or even absorb density perturbations in CDM.
After the last scattering of neutralinos, free streaming induces neutralino
flows from overdense to underdense regions of space. Both damping mechanisms
together define a minimal mass scale for perturbations in neutralino CDM,
before the inhomogeneities enter the nonlinear epoch of structure formation. We
find that the very first gravitationally bound neutralino clouds ought to have
masses above 10^{-6} solar masses, which is six orders of magnitude above the
mass of possible axion miniclusters.",0211325v1
2002-12-09,Galaxies at z=3 around Damped Ly-alpha Clouds,"We are exploring the connection between damped Ly-alpha absorbers (DLAs) and
Lyman break galaxies (LBGs) using deep -- (5sigma)=26 m_{AB}-- broad band
imaging (UBVI) of four wide fields (0.25 sq. deg. each) obtained at the Kitt
Peak 4-m telescope with MOSAIC. Each field contains a damped system at z=3.
  We want to address the nature of DLAs at high-redshifts: (1) Are they
embedded in much larger systems of galaxies? (2) How does the spatial
distribution of LBGs in 3D (space and redshift) correlate with the absorber?
Contrary to most previous DLA studies, we are not looking for the absorber, and
we do not rely on control fields because each of our fields is 40 Mpc
(co-moving) on a side. We present preliminary results in two of our fields. In
one case, we see an indication of an overdensity of galaxies on a scale of 5
Mpc. We discuss the possible implications and sources of contamination of our
results.",0212206v1
2003-04-16,Building Blocks in Hierarchical Clustering Scenarios and their Connection with Damped Ly$α$ Systems,"We carried out a comprehensive analysis of the chemical properties of the
interstellar medium (ISM) and the stellar population (SP) of current normal
galaxies and their progenitors in a hierarchical clustering scenario. We
compared the results with observations of Damped Lyman-$\alpha$ systems (DLAs)
under the hypothesis that, at least, part of the observed DLAs could originate
in the building blocks of today normal galaxies. We used a hydrodynamical
cosmological code which includes star formation and chemical enrichment.
Galaxy-like objects are identified at $z=0$ and then followed back in time.
Random line-of-sights (LOS) are drawn through these structures in order to
mimic Damped Lyman $\alpha$ systems. We then analysed the chemical properties
of the ISM and SP along the LOS. We found that the progenitors of current
galaxies in the field with mean $L <0.5 L^* $ and virial circular velocity of
$100-250 {\rm km/sec}$ could be the associated DLA galaxies. For these systems
we detected a trend for $<L/L^*>$ to increase with redshift.(Abridged)",0304303v2
2003-05-16,The ESI/KeckII Damped Lya Abundance Database,"This paper presents chemical abundance measurements for 37 damped Lya systems
at z>2.5 observed with the Echellette Spectrograph and Imager on the KeckII
telescope. We measure the HI column densities of these damped systems through
Voigt profile fits to their Lya profiles and we implement the apparent optical
depth method to determine ionic column densities. Figures and tables of all
relevant data are presented. A full analysis of the chemical enrichment history
described by these observations will be presented in a future paper. This
dataset is also valuable for efficiently planning future echelle observations
and for rough abundance pattern analyses. We aim to make this entire data set
public within three years of this publication.",0305312v1
2003-10-28,Chemical Abundances in the Damped Lya Systems,"I introduce and review the data and analysis techniques used to measure
abundances in the damped Lya systems, quasar absorption-line systems associated
with galaxies in the early Universe. The observations and issues associated
with their abundance analysis are very similar to those of the Milky Way's
interstellar medium. We measure gas-phase abundances and are therefore subject
to the effects of differential depletion. I review the impact of dust depletion
and then present a summary of current results on the age-metallicity relation
derived from damped Lya systems and new results impacting theories of
nucleosynthesis in the early Universe.",0310814v1
2004-08-10,Cosmic Ray Scattering and Streaming in Compressible Magnetohydrodynamic Turbulence,"Recent advances in understanding of magnetohydrodynamic (MHD) turbulence call
for revisions in the picture of cosmic ray transport. In this paper we use
recently obtained scaling laws for MHD modes to obtain the scattering frequency
for cosmic rays. Using quasilinear theory we calculate gyroresonance with MHD
modes (Alfv\'{e}nic, slow and fast) and transit-time damping (TTD) by fast
modes. We provide calculations of cosmic ray scattering for various phases of
interstellar medium with realistic interstellar turbulence driving that is
consistent with the velocity dispersions observed in diffuse gas. We account
for the turbulence cutoff arising from both collisional and collisionless
damping. We obtain analytical expressions for diffusion coefficients that enter
Fokker-Planck equation describing cosmic ray evolution. We obtain the
scattering rate and show that fast modes provide the dominant contribution to
cosmic ray scattering for the typical interstellar conditions in spite of the
fact that fast modes are subjected to damping. We determine how the efficiency
of the scattering depends on the characteristics of ionized media, e.g. plasma
$\beta$. We calculate the range of energies for which the streaming instability
is suppressed by the ambient MHD turbulence.",0408172v1
2004-12-14,Radiative Effects on Particle Acceleration in Electromagnetic Dominated Outflows,"Plasma outflows from gamma-ray bursts (GRB), pulsar winds, relativistic jets,
and ultra-intense laser targets radiate high energy photons. However, radiation
damping is ignored in conventional PIC simulations. In this letter, we study
the radiation damping effect on particle acceleration via Poynting fluxes in
two-and-half-dimensional particle-in-cell (PIC) plasma simulation of
electron-positron plasmas. Radiation damping force is self-consistently
calculated for each particle and reduces the net acceleration force. The
emitted radiation is peaked within a few degrees from the direction of Poynting
flux and strongly linear-polarized.",0412310v3
2005-09-16,Damped Lyman alpha Systems,"Observations of damped Lyman alpha systems offer a unique window on the
neutral-gas reservoirs that gave rise to galaxies at high redshifts. This
review focuses on critical properties such as the H I and metal content of the
gas and on independent evidence for star formation. Together, these provide an
emerging picture of gravitationally bound objects in which accretion of gas
from the IGM replenishes gas consumed by star formation. Other properties such
as dust content, molecular content, ionized-gas content, gas kinematics, and
galaxy identifications are also reviewed. These properties point to a
multiphase ISM in which radiative and hydrodynamic feedback processes are
present. Numerical simulations and other types of models used to describe
damped Lyman alpha systems within the context of galaxy formation are also
discussed.",0509481v2
2005-11-11,Oscillation mode lifetimes in ksi Hydrae: Will strong mode damping limit asteroseismology of red giant stars?,"We introduce a new method to measure frequency separations and mode lifetimes
of stochastically excited and damped oscillations, so-called solar-like
oscillations. Our method shows that velocity data of the red giant star ksi Hya
(Frandsen et al. 2002) support a large frequency separation between modes of
roughly 7 microHz. We also conclude that the data are consistent with a mode
lifetime of 2 days, which is so short relative to its pulsation period that
none of the observed frequencies are unambiguous. Hence, we argue that the
maximum asteroseismic output that can be obtained from these data is an average
large frequency separation, the oscillation amplitude and the average mode
lifetime. However, the significant discrepancy between the theoretical
calculations of the mode lifetime (Houdek & Gough 2002) and our result based on
the observations of ksi Hya, implies that red giant stars can help us better
understand the damping and driving mechanisms of solar-like p-modes by
convection.",0511344v1
1996-12-14,Nonlinear Landau damping in collisionless plasma and inviscid fluid,"The evolution of an initial perturbation in Vlasov plasma is studied in the
intrinsically nonlinear long-time limit dominated by the effects of particle
trapping. After the possible transient linear exponential Landau damping, the
evolution enters into a universal regime with an algebraically damped electric
field, $E\propto1/t$. The trick used for the Vlasov equation is also applied to
the two-dimensional (2D) Euler equation. It is shown that the stream function
perturbation to a stable shear flow decays as $t^{-5/2}$ in the long-time
limit. These results imply a strong non-ergodicity of the fluid element motion,
which invalidates Gibbs-ensemble-based statistical theories of Vlasov and 2D
fluid turbulence.",9612021v1
1998-03-05,On how a joint interaction of two innocent partners (smooth advection & linear damping) produces a strong intermittency,"Forced advection of passive scalar by a smooth $d$-dimensional incompressible
velocity in the presence of a linear damping is studied. Acting separately
advection and dumping do not lead to an essential intermittency of the steady
scalar statistics, while being mixed together produce a very strong
non-Gaussianity in the convective range: $q$-th (positive) moment of the
absolute value of scalar difference, $<|\theta (t;{\bf r})-\theta (t;0)|^{q}> $
is proportional to $r^{\xi_{q}}$, $\xi _{q}=\sqrt{d^{2}/4+\alpha dq/[
(d-1)D]}-d/2$, where $\alpha /D$ measures the rate of the damping in the units
of the stretching rate. Probability density function (PDF) of the scalar
difference is also found.",9803007v1
1999-02-05,Nonlinear Dynamics of A Damped Magnetic Oscillator,"We consider a damped magnetic oscillator, consisting of a permanent magnet in
a periodically oscillating magnetic field. A detailed investigation of the
dynamics of this dissipative magnetic system is made by varying the field
amplitude $A$. As $A$ is increased, the damped magnetic oscillator, albeit
simple looking, exhibits rich dynamical behaviors such as symmetry-breaking
pitchfork bifurcations, period-doubling transitions to chaos,
symmetry-restoring attractor-merging crises, and saddle-node bifurcations
giving rise to new periodic attractors. Besides these familiar behaviors, a
cascade of ``resurrections'' (i.e., an infinite sequence of alternating
restabilizations and destabilizations) of the stationary points also occurs. It
is found that the stationary points restabilize (destabilize) through
alternating subcritical (supercritical) period-doubling and pitchfork
bifurcations. We also discuss the critical behaviors in the period-doubling
cascades.",9902005v1
1996-09-03,Mode damping in a commensurate monolayer solid,"The normal modes of a commensurate monolayer solid may be damped by mixing
with elastic waves of the substrate. This was shown by B. Hall et al., Phys.
Rev. B 32, 4932 (1985), for perpendicular adsorbate vibrations in the presence
of an isotropic elastic medium. That work is generalized with an elastic
continuum theory of the response of modes of either parallel or perpendicular
polarization for a spherical adsorbate on a hexagonal substrate. The results
are applied to the discussion of computer simulations and inelastic atomic
scattering experiments for adsorbates on graphite. The extreme anisotropy of
the elastic behavior of the graphite leads to quite different wave vector
dependence of the damping for modes polarized perpendicular and parallel to the
substrate. A phenomenological extension of the elasticity theory of the
graphite to include bond-bending energies improves the description of substrate
modes with strong anomalous dispersion and enables a semi-quantitative account
of observed avoided crossings of the adlayer perpendicular vibration mode and
the substrate Rayleigh mode.",9609032v1
1997-12-08,Collective oscillations in superconductors revisited,"In the recent paper Ohashi and Takada (OT) made statements that in the clean
limit considered by us (AV) in 1975, weakly damped collective oscillations in
superconductors do not exist due to the Landau damping and their spectrum
differs from that obtained in AV. In this Comment we would like to note that
these statements arise as a result of a misunderstanding of the term ""clean""
case. OT considered the limit of frequencies larger, than elastic scattering
rate, meanwhile AV obtained weakly damped mode in the case when temperature is
larger than scattering rate, the frequencies being smaller (!) than elastic
scattering rate. All these problems were discussed in our review article in
1979 which was, presumably, unknown to OT.",9712086v1
1999-01-11,Vortex motion in superconducting YBCO inferred from the damping of the oscillations of a levitating magnetic microsphere,"The damping of the oscillations of a small permanent magnet (spherical shape,
radius 0.1 mm) levitating between two parallel YBCO surfaces is measured as a
function of oscillation amplitude and temperature. The losses in the samples
(epitaxial thin films, bulk granular and bulk melt-textured) are analyzed in
terms of oscillating shielding currents flowing through trapped flux lines
whose motion gives rise to electric fields. We find dissipation to originate
from different mechanisms of flux dynamics. At small amplitudes there is a
linear regime described by a surface resistance varying from 10^-9 Ohm for bulk
samples down to 10^-13 Ohm for the thin films at low temperatures. With
increasing amplitude various nonlinear regimes are observed, firstly collective
pinning with diverging energy barriers, secondly in bulk samples above 85 K
hysteretic damping, and finally in thin films exponentially large losses which
can be described by pinning energies vanishing linearly at large currents.",9901085v1
1999-10-07,On the relative positions of the $2Δ$ peaks in Raman and tunneling spectra of d-wave superconductors,"We study $B_{1g}$ Raman intensity $R(\Omega)$ and the density of states
$N(\omega)$ in isotropic 2D d-wave superconductors. For an ideal gas,
$R(\Omega)$ and $N(\omega)$ have sharp peaks at $\Omega =2\Delta$ and $\omega
=\Delta$, respectively, where $\Delta$ is the maximum value of the gap.
  We study how the peak positions are affected by the fermionic damping due to
impurity scattering.
  We show that while the damping generally shifts the peak positions to larger
frequencies, the peak in $R(\Omega)$ still occurs at almost twice the peak
position in $N(\omega)$ and therefore cannot account for the experimentally
observed downturn shift of the peak frequency in $R(\Omega)$ in underdoped
cuprates compared to twice that in $N(\omega)$. We also discuss how the
fermionic damping affects the dynamical spin susceptibility.",9910090v1
1999-11-22,Two-fluid hydrodynamics of a Bose gas including damping from normal fluid transport coefficients,"We extend our recent work on the two-fluid hydrodynamics of the condensate
and non-condensate in a trapped Bose gas by including the dissipation
associated with viscosity and thermal conduction. For purposes of illustration,
we consider the hydrodynamic modes in the case of a uniform Bose gas. A finite
thermal conductivity and shear viscosity give rise to a damping of the first
and second sound modes in addition to that found previously due to the lack of
diffusive equilibrium between the condensate and non-condensate. The
relaxational mode associated with this equilibration process is strongly
coupled to thermal fluctuations and reduces to the usual thermal diffusion mode
above the Bose-Einstein transition. In contrast to the standard Landau
two-fluid hydrodynamics, we predict a damped mode centered at zero frequency,
in addition to the usual second sound doublet.",9911336v1
2000-03-31,Kinetic Theory of Collective Excitations and Damping in Bose-Einstein Condensed Gases,"We calculate the frequencies and damping rates of the low-lying collective
modes of a Bose-Einstein condensed gas at nonzero temperature. We use a complex
nonlinear Schr\""odinger equation to determine the dynamics of the condensate
atoms, and couple it to a Boltzmann equation for the noncondensate atoms. In
this manner we take into account both collisions between
noncondensate-noncondensate and condensate-noncondensate atoms. We solve the
linear response of these equations, using a time-dependent gaussian trial
function for the condensate wave function and a truncated power expansion for
the deviation function of the thermal cloud. As a result, our calculation turns
out to be characterized by two dimensionless parameters proportional to the
noncondensate-noncondensate and condensate-noncondensate mean collision times.
We find in general quite good agreement with experiment, both for the
frequencies and damping of the collective modes.",0003517v1
2000-09-01,The broad Brillouin doublets and central peak of KTaO_3,"The incipient ferroelectric KTaO3 presents low-T Brillouin spectra
anomalies,e.g. a broad central peak (CP), and some additional Brillouin
doublets (BD), whose origin is interpreted in terms of phonon-density
fluctuation processes. A parameterisation from new extensive high-resolution
neutron-scattering measurements is used to show that hydrodynamic second sound
from high damping (compared to BD frequency) TA phonons may exist in the
crystal. Furthermore, low damping thermal phonons may scatter light through
two-phonon difference processes and appear on the Brillouin spectra either as a
sharp or a broader BD, depending on the phonon damping and group velocity . The
comparison between computed anisotropies and experimental measurements favours
the second process.",0009012v1
2001-01-15,Temperature Dependence of Damping and Frequency Shifts of the Scissors Mode of a trapped Bose-Einstein Condensate,"We have studied the properties of the scissors mode of a trapped
Bose-Einstein condensate of $^{87}$Rb atoms at finite temperature. We measured
a significant shift in the frequency of the mode below the hydrodynamic limit
and a strong dependence of the damping rate as the temperature increased. We
compared our damping rate results to recent theoretical calculations for other
observed collective modes finding a fair agreement. From the frequency
measurements we deduce the moment of inertia of the gas and show that it is
quenched below the transition point, because of the superfluid nature of the
condensed gas.",0101213v2
2001-03-16,Gap Anisotropy and de Haas-van Alphen Effect in Type-II Superconductors,"We present a theoretical study on the de Haas-van Alphen (dHvA) oscillation
in the vortex state of type-II superconductors, with a special focus on the
connection between the gap anisotropy and the oscillation damping. Numerical
calculations for three different gap structures clearly indicate that the
average gap along extremal orbits is relevant for the magnitude of the extra
damping, thereby providing a support for experimental efforts to probe gap
anisotropy through the dHvA signal. We also derive an analytic formula for the
extra damping which gives a good fit to the numerical results.",0103336v3
2001-04-10,Quantum phase transitions and collective modes in d-wave superconductors,"Fluctuations near second-order quantum phase transitions in d-wave
superconductors can cause strong damping of fermionic excitations, as observed
in photoemission experiments. The damping of the gapless nodal quasiparticles
can arise naturally in the quantum-critical region of a transition with an
additional spin-singlet, zero momentum order parameter; we argue that the
transition to a d_x^2-y^2 + i d_xy pairing state is the most likely possibility
in this category. On the other hand, the gapped antinodal quasiparticles can be
strongly damped by the coupling to antiferromagnetic spin fluctuations arising
from the proximity to a Neel-ordered state. We review some aspects of the
low-energy field theories for both transitions and the corresponding
quantum-critical behavior. In addition, we discuss the spectral properties of
the collective modes associated with the proximity to a superconductor with
d_x^2-y^2 + i d_xy symmetry, and implications for experiments.",0104176v1
2002-04-11,Nonequilibrium relaxation in neutral BCS superconductors: Ginzburg-Landau approach with Landau damping in real time,"We present a field-theoretical method to obtain consistently the equations of
motion for small amplitude fluctuations of the order parameter directly in real
time for a homogeneous, neutral BCS superconductor. This method allows to study
the nonequilibrium relaxation of the order parameter as an initial value
problem. We obtain the Ward identities and the effective actions for small
phase the amplitude fluctuations to one-loop order. Focusing on the
long-wavelength, low-frequency limit near the critical point, we obtain the
time-dependent Ginzburg-Landau effective action to one-loop order, which is
nonlocal as a consequence of Landau damping. The nonequilibrium relaxation of
the phase and amplitude fluctuations is studied directly in real time. The
long-wavelength phase fluctuation (Bogoliubov-Anderson-Goldstone mode) is
overdamped by Landau damping and the relaxation time scale diverges at the
critical point, revealing critical slowing down.",0204239v2
2002-05-21,Linear spin waves in a trapped Bose gas,"An ultra-cold Bose gas of two-level atoms can be thought of as a spin-1/2
Bose gas. It supports spin-wave collective modes due to the exchange mean
field. Such collective spin oscillations have been observed in recent
experiments at JILA with ${}^{87}$Rb atoms confined in a harmonic trap. We
present a theory of the spin-wave collective modes based on the moment method
for trapped gases. In the collisionless and hydrodynamic limits, we derive
analytic expressions for the frequencies and damping rates of modes with dipole
and quadrupole symmetry. We find that the frequency for a given mode is given
by a temperature independent function of the peak density $n$, and falls off as
$1/n$. We also find that, to a very good approximation, excitations in the
radial and axial directions are decoupled. We compare our model to the
numerical integration of a one dimensional version of the kinetic equation and
find very good qualitative agreement. The damping rates, however, show the
largest deviation for intermediate densities, where one expects Landau damping
-- which is unaccounted for in our moment approach -- to play a significant
role.",0205450v1
2002-08-02,Landau damping of transverse quadrupole oscillations of an elongated Bose-Einstein condensate,"We study the interaction between low-lying transverse collective oscillations
and thermal excitations of an elongated Bose-Einstein condensate by means of
perturbation theory. We consider a cylindrically trapped condensate and
calculate the transverse elementary excitations at zero temperature by solving
the linearized Gross-Pitaevskii equations in two dimensions. We use them to
calculate the matrix elements between thermal excited states coupled with the
quasi-2D collective modes. The Landau damping of transverse collective modes is
investigated as a function of temperature. At low temperatures, the damping
rate due to the Landau decay mechanism is in agreement with the experimental
data for the decay of the transverse quadrupole mode, but it is too small to
explain the slow experimental decay of the transverse breathing mode. The
reason for this discrepancy is discussed.",0208047v1
2002-08-28,Transverse modes of a cigar-shaped Bose-Einstein condensate,"We discuss the collective modes in a harmonically trapped, highly-elongated
Bose condensed gas. The transverse breathing mode exhibits a number of
interesting features, such as the insensitivity of the condensate mode
frequency to the interaction strength, and the closeness of the frequency to
that of the non-condensed thermal cloud in the collisionless limit. Using
finite temperature simulations, we show that these features are responsible for
the very small damping rate observed experimentally. Our results for the
temperature dependence of the damping rate and frequency shift are in excellent
agreement with experiment. We also demonstrate that the unusually small damping
rate does not arise for the $m=2$ mode or for more isotropic trap potentials,
suggesting further possible experimental tests of our theory.",0208567v1
2002-10-31,Stationary quantum statistics of a non-Markovian atom laser,"We present a steady state analysis of a quantum-mechanical model of an atom
laser. A single-mode atomic trap coupled to a continuum of external modes is
driven by a saturable pumping mechanism. In the dilute flux regime, where
atom-atom interactions are negligible in the output, we have been able to solve
this model without making the Born-Markov approximation. The more exact
treatment has a different effective damping rate and occupation of the lasing
mode, as well as a shifted frequency and linewidth of the output. We examine
gravitational damping numerically, finding linewidths and frequency shifts for
a range of pumping rates. We treat mean field damping analytically, finding a
memory function for the Thomas-Fermi regime. The occupation and linewidth are
found to have a nonlinear scaling behavior which has implications for the
stability of atom lasers.",0210688v1
2003-03-23,Damping of micromechanical structures by paramagnetic relaxation,"We find that the damping of micromechanical cantilevers is sensitive to the
relaxation dynamics of paramagnetic ions contained within the levers. We
measure cantilevers containing paramagnetic Mn ions as a function of
temperature, magnetic field, and the vibrational mode of the lever and find
that the levers damping is strongly enhanced by the interplay between the
motion of the lever, the ions magnetic anisotropy, and the ratio of the ions
longitudinal relaxation rate to the resonance frequency of the cantilever. This
enhancement can improve the levers ability to probe the relaxation behavior of
paramagnetic or superparamagetic systems; it may also represent a previously
unrecognized source of intrinsic dissipation in micromechanical structures.",0303489v1
2003-03-27,Oscillatory wave fronts in chains of coupled nonlinear oscillators,"Wave front pinning and propagation in damped chains of coupled oscillators
are studied. There are two important thresholds for an applied constant stress
$F$: for $|F|<F_{cd}$ (dynamic Peierls stress), wave fronts fail to propagate,
for $F_{cd} < |F| < F_{cs}$ stable static and moving wave fronts coexist, and
for $|F| > F_{cs}$ (static Peierls stress) there are only stable moving wave
fronts. For piecewise linear models, extending an exact method of Atkinson and
Cabrera's to chains with damped dynamics corroborates this description. For
smooth nonlinearities, an approximate analytical description is found by means
of the active point theory. Generically for small or zero damping, stable wave
front profiles are non-monotone and become wavy (oscillatory) in one of their
tails.",0303576v1
2003-06-03,Local Relaxation and Collective Stochastic Dynamics,"Damping and thermal fluctuations have been introduced to collective normal
modes of a magnetic system in recent modeling of dynamic thermal magnetization
processes. The connection between this collective stochastic dynamics and
physical local relaxation processes is investigated here. A system of two
coupled magnetic grains embedded in two separate oscillating thermal baths is
analyzed with no \QTR{it}{a priori} assumptions except that of a Markovian
process. It is shown explicitly that by eliminating the oscillating thermal
bath variables, collective stochastic dynamics occurs in the normal modes of
the magnetic system. The grain interactions cause local relaxation to be felt
by the collective system and the dynamic damping to reflect the system
symmetry. This form of stochastic dynamics is in contrast to a common
phenomenological approach where a thermal field is added independently to the
dynamic equations of each discretized cell or interacting grain. The dependence
of this collective stochastic dynamics on the coupling strength of the magnetic
grains and the relative local damping is discussed.",0306047v1
2003-07-22,Classical dynamics of a nano-mechanical resonator coupled to a single-electron transistor,"We analyze the dynamics of a nano-mechanical resonator coupled to a
single-electron transistor (SET) in the regime where the resonator behaves
classically. A master equation is derived describing the dynamics of the
coupled system which is then used to obtain equations of motion for the average
charge state of the SET and the average position of the resonator. We show that
the action of the SET on the resonator is very similar to that of a thermal
bath, as it leads to a steady-state probability-distribution for the resonator
which can be described by mean values of the resonator position, a renormalized
frequency, an effective temperature and an intrinsic damping constant.
Including the effects of extrinsic damping and finite temperature, we find that
there remain experimentally accessible regimes where the intrinsic damping of
the resonator still dominates its behavior. We also obtain the average current
through the SET as a function of the coupling to the resonator.",0307528v1
2003-10-09,Direct measurement of molecular stiffness and damping in confined water layers,"We present {\em direct} and {\em linear} measurements of the normal stiffness
and damping of a confined, few molecule thick water layer. The measurements
were obtained by use of a small amplitude (0.36 $\textrm{\AA}$), off-resonance
Atomic Force Microscopy (AFM) technique. We measured stiffness and damping
oscillations revealing up to 7 layers separated by 2.56 $\pm$ 0.20
$\textrm{\AA}$. Relaxation times could also be calculated and were found to
indicate a significant slow-down of the dynamics of the system as the confining
separation was reduced. We found that the dynamics of the system is determined
not only by the interfacial pressure, but more significantly by solvation
effects which depend on the exact separation of tip and surface. Thus `
solidification\rq seems to not be merely a result of pressure and confinement,
but depends strongly on how commensurate the confining cavity is with the
molecule size. We were able to model the results by starting from the simple
assumption that the relaxation time depends linearly on the film stiffness.",0310219v1
2004-03-08,Mean-field magnetization relaxation in conducting ferromagnets,"Collective ferromagnetic motion in a conducting medium is damped by the
transfer of the magnetic moment and energy to the itinerant carriers. We
present a calculation of the corresponding magnetization relaxation as a
linear-response problem for the carrier dynamics in the effective exchange
field of the ferromagnet. In electron systems with little intrinsic spin-orbit
interaction, a uniform magnetization motion can be formally eliminated by going
into the rotating frame of reference for the spin dynamics. The ferromagnetic
damping in this case grows linearly with the spin-flip rate when the latter is
smaller than the exchange field and is inversely proportional to the spin-flip
rate in the opposite limit. These two regimes are analogous to the
""spin-pumping"" and the ""breathing Fermi-surface"" damping mechanisms,
respectively. In diluted ferromagnetic semiconductors, the hole-mediated
magnetization can be efficiently relaxed to the itinerant-carrier degrees of
freedom due to the strong spin-orbit interaction in the valence bands.",0403224v2
2004-04-05,Low-temperature specific heat of real crystals: Possibility of leading contribution of optical and short-wavelength acoustical vibrations,"We point out that the repeatedly reported glass-like properties of
crystalline materials are not necessarily associated with localized (or
quasilocalized) excitations. In real crystals, optical and short-wavelength
acoustical vibrations remain damped due to defects down to zero temperature. If
such a damping is frequency-independent, e.g. due to planar defects or charged
defects, these optical and short-wavelength acoustical vibrations yield a
linear-in-$T$ contribution to the low-temperature specific heat of the crystal
lattices. At low enough temperatures such a contribution will prevail over that
of the long-wavelength acoustical vibrations (Debye contribution). The
crossover between the linear and the Debye regime takes place at $T^* \propto
\sqrt N$, where $N$ is the concentration of the defects responsible for the
damping. Estimates show that this crossover could be observable.",0404063v4
2004-04-20,Decoherence processes during active manipulation of excitonic qubits in semiconductor quantum dots,"Using photoluminescence spectroscopy, we have investigated the nature of Rabi
oscillation damping during active manipulation of excitonic qubits in
self-assembled quantum dots. Rabi oscillations were recorded by varying the
pulse amplitude for fixed pulse durations between 4 ps and 10 ps. Up to 5
periods are visible, making it possible to quantify the excitation dependent
damping. We find that this damping is more pronounced for shorter pulse widths
and show that its origin is the non-resonant excitation of carriers in the
wetting layer, most likely involving bound-to-continuum and continuum-to-bound
transitions.",0404465v1
2004-05-02,Spin Dynamics and Multiple Reflections in Ferromagnetic Film in Contact with Normal Metal Layers,"Spin dynamics of a metallic ferromagnetic film imbedded between normal metal
layers is studied using the spin-pumping theory of Tserkovnyak et al. [Phys.
Rev. Lett. 88, 117601 (2002)]. The scattering matrix for this structure is
obtained using a spin-dependent potential with quantum well in the
ferromagnetic region. Owing to multiple reflections in the well, the excess
Gilbert damping and the gyromagnetic ratio exhibit quantum oscillations as a
function of the thickness of the ferromagnetic film. The wavelength of the
oscillations is given by the depth of the quantum well. For iron film imbedded
between gold layers, the amplitude of the oscillations of the Gilbert damping
is in an order of magnitude agreement with the damping observed by Urban et al.
[Phys. Rev. Lett. 87, 217204 (2001)]. The results are compared with the linear
response theory of Mills [Phys. Rev. B 68, 0144419 (2003)].",0405020v1
2004-06-18,Spin pumping and magnetization dynamics in ferromagnet-Luttinger liquid junctions,"We study spin transport between a ferromagnet with time-dependent
magnetization and a conducting carbon nanotube or quantum wire, modeled as a
Luttinger liquid. The precession of the magnetization vector of the ferromagnet
due for instance to an outside applied magnetic field causes spin pumping into
an adjacent conductor. Conversely, the spin injection causes increased
magnetization damping in the ferromagnet. We find that, if the conductor
adjacent to the ferromagnet is a Luttinger liquid, spin pumping/damping is
suppressed by interactions, and the suppression has clear Luttinger liquid
power law temperature dependence. We apply our result to a few particular
setups. First we study the effective Landau-Lifshitz-Gilbert (LLG) coupled
equations for the magnetization vectors of the two ferromagnets in a FM-LL-FM
junction. Also, we compute the Gilbert damping for a FM-LL and a FM-LL-metal
junction.",0406437v1
2004-07-29,From subdiffusion to superdiffusion of particles on solid surfaces,"We present a numerical and partially analytical study of classical particles
obeying a Langevin equation that describes diffusion on a surface modeled by a
two dimensional potential. The potential may be either periodic or random.
Depending on the potential and the damping, we observe superdiffusion,
large-step diffusion, diffusion, and subdiffusion. Superdiffusive behavior is
associated with low damping and is in most cases transient, albeit often long.
Subdiffusive behavior is associated with highly damped particles in random
potentials. In some cases subdiffusive behavior persists over our entire
simulation and may be characterized as metastable. In any case, we stress that
this rich variety of behaviors emerges naturally from an ordinary Langevin
equation for a system described by ordinary canonical Maxwell-Boltzmann
statistics.",0407781v1
2004-08-18,Theory of Magnetic Polaron,"The concept of magnetic polaron is analysed and developed to elucidate the
nature of itinerant charge carrier states in magnetic semiconductors and
similar complex magnetic materials. By contrasting the scattering and bound
states of carriers within the $s-d$ exchange model, the nature of bound states
at finite temperatures is clarified. The free magnetic polaron at certain
conditions is realized as a bound state of the carrier (electron or hole) with
the spin wave. Quite generally, a self-consistent theory of a magnetic polaron
is formulated within a nonperturbative many-body approach, the Irreducible
Green Functions (IGF) method which is used to describe the quasiparticle
many-body dynamics at finite temperatures. Within the above many-body approach
we elaborate a self-consistent picture of dynamic behavior of two interacting
subsystems, the localized spins and the itinerant charge carriers. In
particular, we show that the relevant generalized mean fields emerges naturally
within our formalism. At the same time, the correct separation of elastic
scattering corrections permits one to consider the damping effects (inelastic
scattering corrections) in the unified and coherent fashion. The damping of
magnetic polaron state, which is quite different from the damping of the
scattering states, finds a natural interpretation within the present
self-consistent scheme.",0408404v2
2004-09-27,Dephasing and delay time fluctuations in the chaotic scattering of a quantum particle weakly coupled to a complicated background,"Effect of a complicated many-body environment is analyzed on the chaotic
motion of a quantum particle in a mesoscopic ballistic structure. The dephasing
and absorption phenomena are treated on the same footing in the framework of a
schematic microscopic model. The single-particle doorway resonance states
excited in the structure via an external channel are damped not only because of
the escape onto such channels but also due to ulterior population of the
long-lived background states. The transmission through the structure is
presented as an incoherent sum of the flow formed by the interfering damped
doorway resonances and the retarded flow of the particles reemitted by the
environment. The resulting internal damping as well as the dephasing rate are
uniquely expressed in terms of the spreading width which controls the coupling
to the background. The formation of the long-lived fine-structure resonances
strongly enhances delay time fluctuations thus broadening the delay time
distribution.",0409690v1
2004-10-30,Dynamics of Domain Wall in a Biaxial Ferromagnet With Spin-torque,"The dynamics of the domain wall (DW) in a biaxial ferromagnet interacting
with a spin-polarized current are described by sine-gordon (SG) equation
coupled with Gilbert damping term in this paper. Within our frame-work of this
model, we obtain a threshold of the current in the motion of a single DW with
the perturbation theory on kink soliton solution to the corresponding
ferromagnetic system, and the threshold is shown to be dependent on the Gilbert
damping term. Also, the motion properties of the DW are discussed for the zero-
and nonzero-damping cases, which shows that our theory to describe the dynamics
of the DW are self-consistent.",0411005v3
2005-01-18,Damping effects and the metal-insulator transition in the two-dimensional electron gas,"The damping of single-particle degrees of freedom in strongly correlated
two-dimensional Fermi systems is analyzed. Suppression of the scattering
amplitude due to the damping effects is shown to play a key role in preserving
the validity of the Landau-Migdal quasiparticle picture in a region of a phase
transition, associated with the divergence of the quasiparticle effective mass.
The results of the analysis are applied to elucidate the behavior of the
conductivity $\sigma(T)$ of the two-dimensional dilute electron gas in the
density region where it undergoes a metal-insulator transition.",0501427v2
2005-04-17,Dynamics of thermoelastic thin plates: A comparison of four theories,"Four distinct theories describing the flexural motion of thermoelastic thin
plates are compared. The theories are due to Chadwick, Lagnese and Lions,
Simmonds, and Norris. Chadwick's theory requires a 3D spatial equation for the
temperature but is considered the most accurate as the others are derivable
from it by different approximations. Attention is given to the damping of
flexural waves. Analytical and quantitative comparisons indicate that the
Lagnese and Lions model with a 2D temperature equation captures the essential
features of the thermoelastic damping, but contains systematic inaccuracies.
These are attributable to the approximation for the first moment of the
temperature used in deriving the Lagnese and Lions equation. Simmonds' model
with an explicit formula for temperature in terms of plate deflection is the
simplest of all but is accurate only at low frequency, where the damping is
linearly proportional to the frequency. It is shown that the Norris model,
which is almost as simple as Simmond's, is as accurate as the more precise but
involved theory of Chadwick.",0504412v1
2005-04-29,Probing temperature and damping rates in Bose-Einstein condensates using ultraslow light experiments,"We propose a method to probe Landau and Beliaev processes in dilute trapped
atomic condensates with a multiple state structure using ultraslow light
experimental configurations. Under certain conditions, damping rates from these
collisional processes are directly proportional to the dephasing rates, making
it possible to determine damping rates through measurement of the dephasing. In
the ultraslow light systems we consider, Landau decay rates are enhanced at low
momenta, which allows one to distinguish between Landau-dominated and
Beliaev-dominated regimes at the same temperature. Furthermore, the enhancement
of Landau rates potentially provides a way to measure low temperatures ($T \ll
T_c$) in dilute condensates more accurately than current methods permit.",0504784v2
2005-05-23,Anharmonic vs. relaxational sound damping in glasses: I. Brillouin scattering from densified silica,"This series discusses the origin of sound damping and dispersion in glasses.
In particular, we address the relative importance of anharmonicity versus
thermally activated relaxation. In this first article, Brillouin-scattering
measurements of permanently densified silica glass are presented. It is found
that in this case the results are compatible with a model in which damping and
dispersion are only produced by the anharmonic coupling of the sound waves with
thermally excited modes. The thermal relaxation time and the unrelaxed velocity
are estimated.",0505558v3
2005-05-23,Anharmonic vs. relaxational sound damping in glasses: II. Vitreous silica,"The temperature dependence of the frequency dispersion in the sound velocity
and damping of vitreous silica is reanalyzed. Thermally activated relaxation
accounts for the sound attenuation observed above 10 K at sonic and ultrasonic
frequencies. Its extrapolation to the hypersonic regime reveals that the
anharmonic coupling to the thermal bath becomes important in
Brillouin-scattering measurements. At 35 GHz and room temperature, the damping
due to this anharmonicity is found to be nearly twice that produced by
thermally activated relaxation. The analysis also reveals a sizeable velocity
increase with temperature which is not related with sound dispersion. This
suggests that silica experiences a gradual structural change that already
starts well below room temperature.",0505560v2
2005-06-06,Heat Bath Approach to Landau Damping and Pomeranchuk Quantum Critical Points,"We study the problem of the damping of collective modes close to a
Pomeranchuk quantum critical point in a Fermi liquid. In analogy with problems
in dissipative open quantum systems, we derive the Landau damping of a Fermi
liquid by integrating out a macroscopic number of degrees of freedom from a
generating functional. Being a reformulation of the linearized Boltzmann
equation this approach reproduces well-known results from the theory of Fermi
liquids. We also study the Bethe-Salpeter equations within the Landau theory
and discuss the implications of these results on quantum phase transitions of
the Pomeranchuk type and its dynamical exponent, z. We apply our results to the
electronic nematic instability and find z=3 in the collisionless limit.",0506146v3
2005-07-01,Measurement of Dissipation of a Three-Level rf SQUID Qubit,"The dissipation-induced relaxation (T_1) time of a macroscopic quantum system
- a \{lambda}-type three-level rf SQUID flux qubit weakly coupled to control
and readout circuitry (CRC) - is investigated via time-domain measurement. The
measured interwell relaxation time of the qubit's first excited state,
T_1=3.45+/-0.06 \{mu}s, corresponds to an effective damping resistance of the
flux qubit R=1.6+/-0.1 M\{omega} which is much lower than the intrinsic
quasiparticle resistance of the Josephson tunnel junction. An analysis of the
system shows that although the CRC is very weakly coupled to the qubit it is
the primary source of damping. This type of damping can be significantly
reduced by the use of more sophisticated circuit design to allow coherent
manipulation of qubit states.",0507008v1
2005-09-19,Interaction effects on magnetooscillations in a two-dimensional electron gas,"Motivated by recent experiments, we study the interaction corrections to the
damping of magnetooscillations in a two-dimensional electron gas (2DEG). We
identify leading contributions to the interaction-induced damping which are
induced by corrections to the effective mass and quantum scattering time. The
damping factor is calculated for Coulomb and short-range interaction in the
whole range of temperatures, from the ballistic to the diffusive regime. It is
shown that the dominant effect is that of the renormalization of the effective
electron mass due to the interplay of the interaction and impurity scattering.
The results are relevant to the analysis of experiments on magnetooscillations
(in particular, for extracting the value of the effective mass) and are
expected to be useful for understanding the physics of a high-mobility 2DEG
near the apparent metal-insulator transition.",0509463v2
2005-10-31,Time-Resolved Spin Torque Switching and Enhanced Damping in Py/Cu/Py Spin-Valve Nanopillars,"We report time-resolved measurements of current-induced reversal of a free
magnetic layer in Py/Cu/Py elliptical nanopillars at temperatures T = 4.2 K to
160 K. Comparison of the data to Landau-Lifshitz-Gilbert macrospin simulations
of the free layer switching yields numerical values for the spin torque and the
Gilbert damping parameters as functions of T. The damping is strongly
T-dependent, which we attribute to the antiferromagnetic pinning behavior of a
thin permalloy oxide layer around the perimeter of the free layer. This
adventitious antiferromagnetic pinning layer can have a major impact on spin
torque phenomena.",0510798v2
2005-12-20,Damping of zero sound in Luttinger liquids,"We calculate the damping gamma_q of collective density oscillations (zero
sound) in a one-dimensional Fermi gas with dimensionless forward scattering
interaction F and quadratic energy dispersion k^2 / 2 m at zero temperature.
For wave-vectors | q| /k_F small compared with F we find to leading order
gamma_q = v_F^{-1} m^{-2} Y (F) | q |^3, where v_F is the Fermi velocity, k_F
is the Fermi wave-vector, and Y (F) is proportional to F^3 for small F. We also
show that zero-sound damping leads to a finite maximum proportional to |k - k_F
|^{-2 + 2 eta} of the charge peak in the single-particle spectral function,
where eta is the anomalous dimension. Our prediction agrees with photoemission
data for the blue bronze K_{0.3}MoO_3.",0512494v4
2006-04-11,Damping and dispersion of oscillating modes of a multicomponent ionic mixture in a magnetic field,"The collective-mode spectrum of a multicomponent magnetized ionic mixture for
small wave number k is studied with the use of magnetohydrodynamics and formal
kinetic theory. Apart from the usual thermal and diffusive modes, the spectrum
contains a set of four oscillating modes. By evaluating the k^2 contributions
to the eigenfrequencies, the damping and the dispersion of these oscillating
modes are determined. The long-range nature of the Coulomb interactions is
shown to imply that Burnett terms with higher-order gradients in the linear
phenomenological laws have to be taken into account in order to obtain a full
description of all damping and dispersion effects.",0604272v1
2006-05-16,Collective mode damping and viscosity in a 1D unitary Fermi gas,"We calculate the damping of the Bogoliubov-Anderson mode in a one-dimensional
two-component attractive Fermi gas for arbitrary coupling strength within a
quantum hydrodynamic approach. Using the Bethe-Ansatz solution of the 1D
BCS-BEC crossover problem, we derive analytic results for the viscosity
covering the full range from a Luther-Emery liquid of weakly bound pairs to a
Lieb-Liniger gas of strongly bound bosonic dimers. At the unitarity point, the
system is a Tonks-Girardeau gas with a universal constant $\alpha_{\zeta}=0.38$
in the viscosity $\zeta=\alpha_{\zeta}\hbar n$ for T=0. For the trapped case,
we calculate the Q-factor of the breathing mode and show that the damping
provides a sensitive measure of temperature in 1D Fermi gases.",0605413v2
2006-06-09,Spin wave dynamics and the determination of intrinsic Gilbert damping in locally-excited Permalloy thin films,"Time-resolved scanning Kerr effect microscopy has been used to study
magnetization dynamics in Permalloy thin films excited by transient magnetic
pulses generated by a micrometer-scale transmission line structure. The results
are consistent with magnetostatic spin wave theory and are supported by
micromagnetic simulations. Magnetostatic volume and surface spin waves are
measured for the same specimen using different bias field orientations and can
be accurately calculated by k-space integrations over all excited plane wave
components. A single damping constant of Gilbert form is sufficient to describe
both scenarios. The nonuniform pulsed field plays a key role in the spin wave
dynamics, with its Fourier transform serving as a weighting function for the
participating modes. The intrinsic Gilbert damping parameter $\alpha$ is most
conveniently measured when the spin waves are effectively stationary.",0606235v3
2006-07-06,Low energy theory of a single vortex and electronic quasiparticles in a d-wave superconductor,"We highlight the properties of a simple model (contained in our recent work)
of the quantum dynamics of a single point vortex interacting with the nodal
fermionic quasiparticles of a d-wave superconductor. We describe the
renormalization of the vortex motion by the quasiparticles: at T=0, the
quasiparticles renormalize the vortex mass and introduce only a weak sub-Ohmic
damping. Ohmic (or `Bardeen-Stephen' damping) appears at T>0, with the damping
co-efficient vanishing ~ T^2 with a universal prefactor. Conversely, quantum
fluctuations of the vortex renormalize the quasiparticle spectrum. A point
vortex oscillating in a harmonic pinning potential has no zero-bias peak in the
electronic local density of states (LDOS), but has small satellite features at
an energy determined by the pinning potential. These are proposed as the origin
of sub-gap LDOS peaks observed in scanning tunneling microscopic studies of the
LDOS near a vortex.",0607137v2
2006-09-18,General Form of Magnetization Damping: Magnetization dynamics of a spin system evolving nonadiabatically and out of equilibrium,"Using an effective Hamiltonian including the Zeeman and internal
interactions, we describe the quantum theory of magnetization dynamics when the
spin system evolves non-adiabatically and out of equilibrium. The
Lewis-Riesenfeld dynamical invariant method is employed along with the
Liouville-von Neumann equation for the density matrix. We derive a dynamical
equation for magnetization defined with respect to the density operator with a
general form of magnetization damping that involves the non-equilibrium
contribution in addition to the Landau-Lifshitz-Gilbert equation. Two special
cases of the radiation-spin interaction and the spin-spin exchange interaction
are considered. For the radiation-spin interaction, the damping term is shown
to be of the Gilbert type, while in the spin-spin exchange interaction case the
results depend on a coupled chain of correlation functions.",0609431v2
2005-08-23,Investigations of Process Damping Forces in Metal Cutting,"Using finite element software developed for metal cutting by Third Wave
Systems we investigate the forces involved in chatter, a self-sustained
oscillation of the cutting tool. The phenomena is decomposed into a vibrating
tool cutting a flat surface work piece, and motionless tool cutting a work
piece with a wavy surface. While cutting the wavy surface, the shearplane was
seen to oscillate in advance of the oscillation of the depth of cut, as were
the cutting, thrust, and shear plane forces. The vibrating tool was used to
investigate process damping through the interaction of the relief face of the
tool and the workpiece. Crushing forces are isolated and compared to the
contact length between the tool and workpiece. We found that the wavelength
dependence of the forces depended on the relative size of the wavelength to the
length of the relief face of the tool. The results indicate that the damping
force from crushing will be proportional to the cutting speed for short tools,
and inversely proportional for long tools.",0508102v1
1999-09-27,R-Modes in Superfluid Neutron Stars,"The analogs of r-modes in superfluid neutron stars are studied here. These
modes, which are governed primarily by the Coriolis force, are identical to
their ordinary-fluid counterparts at the lowest order in the small
angular-velocity expansion used here. The equations that determine the next
order terms are derived and solved numerically for fairly realistic superfluid
neutron-star models. The damping of these modes by superfluid ``mutual
friction'' (which vanishes at the lowest order in this expansion) is found to
have a characteristic time-scale of about 10^4 s for the m=2 r-mode in a
``typical'' superfluid neutron-star model. This time-scale is far too long to
allow mutual friction to suppress the recently discovered gravitational
radiation driven instability in the r-modes. However, the strength of the
mutual friction damping depends very sensitively on the details of the
neutron-star core superfluid. A small fraction of the presently acceptable
range of superfluid models have characteristic mutual friction damping times
that are short enough (i.e. shorter than about 5 s) to suppress the
gravitational radiation driven instability completely.",9909084v1
2001-02-08,Cyclotron damping and Faraday rotation of gravitational waves,"We study the propagation of gravitational waves in a collisionless plasma
with an external magnetic field parallel to the direction of propagation. Due
to resonant interaction with the plasma particles the gravitational wave
experiences cyclotron damping or growth, the latter case being possible if the
distribution function for any of the particle species deviates from
thermodynamical equilibrium. Furthermore, we examine how the damping and
dispersion depends on temperature and on the ratio between the cyclotron- and
gravitational wave frequency. The presence of the magnetic field leads to
different dispersion relations for different polarizations, which in turn imply
Faraday rotation of gravitational waves.",0102031v2
2007-02-07,Relativistic r-modes and shear viscosity,"We derive the relativistic equations for stellar perturbations, including in
a consistent way shear viscosity in the stress-energy tensor, and we
numerically integrate our equations in the case of large viscosity. We consider
the slow rotation approximation, and we neglect the coupling between polar and
axial perturbations. In our approach, the frequency and damping time of the
emitted gravitational radiation are directly obtained. We find that,
approaching the inviscid limit from the finite viscosity case, the continuous
spectrum is regularized. Constant density stars, polytropic stars, and stars
with realistic equations of state are considered. In the case of constant
density stars and polytropic stars, our results for the viscous damping times
agree, within a factor two, with the usual estimates obtained by using the
eigenfunctions of the inviscid limit. For realistic neutron stars, our
numerical results give viscous damping times with the same dependence on mass
and radius as previously estimated, but systematically larger of about 60%.",0702040v1
2000-08-18,Fabrication Process of Rounded Damped Detuned Structure,"Following the successful design and fabrication of Damped Detuned Structures
(DDS), the JLC/NLC linear collider project advanced to Rounded Damped Detuned
Structures (RDDS) with curved cross section of the cavity shape for increased
shunt impedance. Various advanced techniques for fabricating RDDS1 disks
comparing to those for DDS were established to satisfy the dimension accuracy
of +-1 micron over the entire surface made by ultra-precision turning. These
disks were assembled with almost the same stacking and bonding jigs and
processes as those of DDS3 assembly. In consequence, the assembly showed little
disk-to-disk misalignment within 1 micron before and after the process. Though,
it had 200 micron smooth bowing, which was subsequently corrected as DDS3, and
flares at both ends.",0008034v1
2000-08-18,Meeting Tight Frequency Requirement of Rounded Damped Detuned Structure,"Following successful design and fabrication of damped detuned structures, the
R&D for the accelerating structures of the NLC/JLC linear collider project
proceeded to studies of Rounded Damped Detuned Structure with curved cross
section of the cavity shape for increased shunt impedance. The important
features of the structure are the accurately tuned accelerating mode frequency
and the distribution of the first dipole modes smooth and close to the design
distribution. These requirements were met based on the high-accuracy diamond
turning with its capability to realize the periphery tolerance of two microns.
The lowest dipole mode frequencies scattered by 0.6 MHz RMS. The error in the
accelerating mode frequency averaged over a structure was 0.1 MHz by applying a
feed-forward method.",0008035v1
1992-03-16,Comment on ``Damping of energetic gluons and quarks in high-temperature QCD'',"Burgess and Marini have recently pointed out that the leading contribution to
the damping rate of energetic gluons and quarks in the QCD plasma, given by
$\gamma=c g^2\ln(1/g)T$, can be obtained by simple arguments obviating the need
of a fully resummed perturbation theory as developed by Braaten and Pisarski.
Their calculation confirmed previous results of Braaten and Pisarski, but
contradicted those proposed by Lebedev and Smilga. While agreeing with the
general considerations made by Burgess and Marini, I correct their actual
calculation of the damping rates, which is based on a wrong expression for the
static limit of the resummed gluon propagator. The effect of this, however,
turns out to be cancelled fortuitously by another mistake, so as to leave all
of their conclusions unchanged. I also verify the gauge independence of the
results, which in the corrected calculation arises in a less obvious manner.",9203211v1
1995-02-16,The Infrared Sensitivity of Screening and Damping in a Quark-Gluon Plasma,"All the next-to-leading order contributions to the quasi-particle dispersion
laws of a quark-gluon plasma which due to infrared singularities are sensitive
to the magnetic-mass scale are calculated using Braaten-Pisarski resummation.
These relative-order-$g\ln(g)$ corrections are shown here to generally
contribute to the dynamical screening of gluonic fields with frequencies below
the plasma frequency as well as to the damping of propagating gluonic and
fermionic quasi-particles. In the limit of vanishing wave-vector the infrared
singularities disappear, but in a way that raises the possibility for formally
higher orders of the Braaten-Pisarski scheme to equally contribute at
next-to-leading order when the wave-vector is of the order of or less than the
magnetic-mass scale. This is argued to be a problem in particular for the
fermionic damping rate.",9502324v1
1997-10-30,Damping rate for transverse gluons with finite soft momentum in hot QCD,"We calculate the damping rate for transverse gluons with {\nineti finite}
soft momentum to leading order in perturbative hot QCD. The internal momenta of
the one-loop contributing diagrams are soft. This means we have to use
effective vertices and propagators which incorporate the so-called hard thermal
loops. We expand the damping rate in powers of the incoming momentum and argue
that the series ought to converge within a finite radius of convergence. We
contrast such a behavior with the one obtained from a previous calculation that
produced a logarithmic behavior, a calculation based on letting the gluon
momentum come from the hard limit down towards the interior of the soft region.
This difference in behavior may point to interesting physics around some
`critical' region.",9710549v2
1998-07-21,An infrared singularity in the damping rate for longitudinal gluons in hot QCD,"We calculate $\gamma_l(0)$, the damping rate for longitudinal on-shell gluons
with zero momentum in hot QCD using the hard-thermal-loop (htl) scheme. We find
it to be divergent in the infrared, which means that in this scheme
$\gamma_l(0)$ is different from $\gamma_t(0)$, the corresponding damping rate
for transverse gluons which is known to be finite. This result suggests that
the htl scheme is infrared sensitive and thus may need to be improved upon in
this sector. We discuss this issue after we present our calculation.",9807439v2
1998-09-25,Damping rates in the MSSM and electroweak baryogenesis,"We present an analysis of the thermalization rate of Higgsinos and winos
based on the imaginary part of the two-point Green function in the {\it
unbroken} phase of the MSSM. We use improved propagators including resummation
of hard thermal loops and the thermalization rate is computed at the one-loop
level in the high temperature approximation. We find that the damping is
typically dominated by scattering with gauge bosons, resulting in a damping
rate of about $\gamma_{\Ht}\simeq 0.025T$, $\gamma_{\Wt}\simeq 0.065T$. The
contribution from scattering with scalars is relatively small. Implications for
baryogenesis are also discussed.",9809529v1
2006-10-27,The soft fermion dispersion relation at next-to-leading order in hot QED,"We study next-to-leading order contributions to the soft static fermion
dispersion relation in hot QED. We derive an expression for the complete
next-to-leading order contribution to the retarded fermion self-energy. The
real and imaginary parts of this expression give the next-to-leading order
contributions to the mass and damping rate of the fermionic quasi-particle.
Many of the terms that are expected to contribute according to the traditional
power counting argument are actually subleading. We explain why the power
counting method over estimates the contribution from these terms. For the
electron damping rate in QED we obtain: $\gamma_{QED} = \frac{e^2
T}{4\pi}(2.70)$. We check our method by calculating the next-to-leading order
contribution to the damping rate for the case of QCD with two flavours and
three coulours. Our result agrees with the result obtained previously in the
literature. The numerical evaluation of the nlo contribution to the mass is
left to a future publication.",0610372v1
2007-03-26,Preheating and Affleck-Dine leptogenesis after thermal inflation,"Previously, we proposed a model of low energy Affleck-Dine leptogenesis in
the context of thermal inflation. The lepton asymmetry is generated at the end
of thermal inflation, which occurs at a relatively low energy scale with the
Hubble parameter somewhere in the range $1 \keV \lesssim H \lesssim 1 \MeV$.
Thus Hubble damping will be ineffective in bringing the Affleck-Dine field into
the lepton conserving region near the origin, leaving the possibility that the
lepton number could be washed out. Previously, we suggested that preheating
could damp the amplitude of the Affleck-Dine field allowing conservation of the
lepton number. In this paper, we demonstrate numerically that preheating does
efficiently damp the amplitude of the Affleck-Dine field and that the lepton
number is conserved as the result. In addition to demonstrating a crucial
aspect of our model, it also opens the more general possibility of low energy
Affleck-Dine baryogenesis.",0703275v1
2002-08-31,Neutrino damping rate at finite temperature and density,"A first principle derivation is given of the neutrino damping rate in
real-time thermal field theory. Starting from the discontinuity of the neutrino
self energy at the two loop level, the damping rate can be expressed as
integrals over space phase of amplitudes squared, weighted with statistical
factors that account for the possibility of particle absorption or emission
from the medium. Specific results for a background composed of neutrinos,
leptons, protons and neutrons are given. Additionally, for the real part of the
dispersion relation we discuss the relation between the results obtained from
the thermal field theory, and those obtained by the thermal average of the
forward scattering amplitude.",0209006v1
2004-10-20,Ergodicity for the weakly damped stochastic non-linear Schrödinger equations,"We study a damped stochastic non-linear Schr\""{o}dinger (NLS) equation driven
by an additive noise. It is white in time and smooth in space. Using a coupling
method, we establish convergence of the Markovian transition semi-group toward
a unique invariant probability measure. This kind of method was originally
developped to prove exponential mixing for strongly dissipative equations such
as the Navier-Stokes equations. We consider here a weakly dissipative equation,
the damped nonlinear Schr\""{o}dinger equation in the one dimensional cubic
case. We prove that the mixing property holds and that the rate of convergence
to equilibrium is at least polynomial of any power.",0410443v2
2006-07-30,Non-autonomous dynamics of wave equations with nonlinear damping and critical nonlinearity,"The authors consider non-autonomous dynamical behavior of wave-type
evolutionary equations with nonlinear damping and critical nonlinearity. These
type of waves equations are formulated as non-autonomous dynamical systems
(namely, cocycles). A sufficient and necessary condition for the existence of
pullback attractors is established for norm-to-weak continuous non-autonomous
dynamical systems, in terms of pullback asymptotic compactness or pullback
$\kappa-$contraction criteria. A technical method for verifying pullback
asymptotic compactness, via contractive functions, is devised. These results
are then applied to the wave-type evolutionary equations with nonlinear damping
and critical nonlinearity, to obtain the existence of pullback attractors. The
required pullback asymptotic compactness for the existence of pullback
attractors is fulfilled by some new a priori estimates for concrete wave type
equations arising from applications. Moreover, the pullback
$\kappa-$contraction criterion for the existence of pullback attractors is of
independent interest.",0607774v3
2000-09-28,"Quantization of Damped Harmonic Oscillator, Thermal Field Theories and q-Groups","We study the canonical quantization of the damped harmonic oscillator by
resorting to the realization of the q-deformation of the Weyl-Heisenberg
algebra (q-WH) in terms of finite difference operators. We relate the damped
oscillator hamiltonian to the q-WH algebra and to the squeezing generator of
coherent states theory. We also show that the q-WH algebra is the natural
candidate to study thermal field theory. The well known splitting, in the
infinite volume limit, of the space of physical states into unitarily
inequivalent representations of the canonical commutation relations is briefly
commented upon in relation with the von Neumann theorem in quantum mechanics
and with q-WH algebra.",0009036v1
2001-11-14,"Soliton-radiation coupling in the parametrically driven, damped nonlinear Schrödinger equation","We use the Riemann-Hilbert problem to study the interaction of the soliton
with radiation in the parametrically driven, damped nonlinear Schr\""odinger
equation. The analysis is reduced to the study of a finite-dimensional
dynamical system for the amplitude and phase of the soliton and the complex
amplitude of the long-wavelength radiation. In contrast to previously utilised
Inverse Scattering-based perturbation techniques, our approach is valid for
arbitrarily large driving strengths and damping coefficients. We show that,
contrary to suggestions made in literature, the complexity observed in the
soliton's dynamics cannot be accounted for just by its coupling to the
long-wavelength radiation.",0111034v1
2002-02-12,Landau Damping and Coherent Structures in Narrow-Banded 1+1 Deep Water Gravity Waves,"We study the nonlinear energy transfer around the peak of the spectrum of
surface gravity waves by taking into account nonhomogeneous effects. In the
narrow-banded approximation the kinetic equation resulting from a
nonhomogeneous wave field is a Vlasov-Poisson type equation which includes at
the same time the random version of the Benjamin-Feir instability and the
Landau damping phenomenon. We analytically derive the values of the Phillips'
constant $\alpha$ and the enhancement factor $\gamma$ for which the
narrow-banded approximation of the JONSWAP spectrum is unstable. By performing
numerical simulations of the nonlinear Schr\""{o}dinger equation we check the
validity of the prediction of the related kinetic equation. We find that the
effect of Landau damping is to suppress the formation of coherent structures.
The problem of predicting freak waves is briefly discussed.",0202026v1
2005-10-24,Stability of a nonlinear oscillator with random damping,"A noisy damping parameter in the equation of motion of a nonlinear oscillator
renders the fixed point of the system unstable when the amplitude of the noise
is sufficiently large. However, the stability diagram of the system can not be
predicted from the analysis of the moments of the linearized equation. In the
case of a white noise, an exact formula for the Lyapunov exponent of the system
is derived. We then calculate the critical damping for which the {\em
nonlinear} system becomes unstable. We also characterize the intermittent
structure of the bifurcated state above threshold and address the effect of
temporal correlations of the noise by considering an Ornstein-Uhlenbeck noise.",0510063v1
2006-10-20,Vibration of Generalized Double Well Oscillators,"We have applied the Melnikov criterion to examine a global homoclinic
bifurcation and transition to chaos in a case of a double well dynamical system
with a nonlinear fractional damping term and external excitation. The usual
double well Duffing potential having a negative square term and positive
quartic term has been generalized to a double well potential with a negative
square term and a positive one with an arbitrary real exponent $q > 2$. We have
also used a fractional damping term with an arbitrary power $p$ applied to
velocity which enables one to cover a wide range of realistic damping factors:
from dry friction $p \to 0$ to turbulent resistance phenomena $p=2$.
  Using perturbation methods we have found a critical forcing amplitude $\mu_c$
above which the system may behave chaotically. Our results show that the
vibrating system is less stable in transition to chaos for smaller $p$
satisfying an exponential scaling low. The critical amplitude $\mu_c$ as an
exponential function of $p$.
  The analytical results have been illustrated by numerical simulations using
standard nonlinear tools such as
  Poincare maps and the maximal Lyapunov exponent. As usual for chosen system
parameters we have identified a chaotic motion above the critical Melnikov
amplitude $\mu_c$.",0610052v1
1998-06-18,Relativity Damps OPEP in Nuclear Matter,"Using a relativistic Dirac-Brueckner analysis the OPEP contribution to the
ground state energy of nuclear matter is studied. In the study the pion is
derivative-coupled. We find that the role of the tensor force in the saturation
mechanism is substantially reduced compared to its dominant role in a usual
nonrelativistic treatment. We show that the damping of derivative-coupled OPEP
is actually due to the decrease of $M^*/M$ with increasing density. We point
out that if derivative-coupled OPEP is the preferred form of nuclear effective
lagrangian nonrelativistic treatment of nuclear matter is in trouble. Lacking
the notion of $M^*$ it cannot replicate the damping. We suggest an examination
of the feasibility of using pseudoscalar coupled $\pi$N interaction before
reaching a final conclusion about nonrelativistic treatment of nuclear matter.",9806054v1
1999-07-05,Damping of IVGDR - Fermi-liquid or Fermi-gas ?,"Collisional relaxation rates of collective modes in nuclei are calculated
using the Levinson equation for the reduced density matrix with a memory
dependent collision term. Linearizing the collision integral two contribution
have to be distinguished, the one from the quasiparticle energy and the one
from occupation factors. The first one yields the known Landau formula of zero
sound damping and the second one leads to the Fermi gas model of Ref.1 with the
additional factor 3 in front of the frequencies. Adding both contribution we
obtain a final relaxation rate for the Fermi liquid model. Calculations of the
temperature dependence of the damping rates and of the shape evolution of IVGDR
are in good agreement with the experiment and show only minor differences
between both models.",9907012v1
2001-01-08,Collisional Damping of Giant Monopole and Quadrupole Resonances,"Collisional damping widths of giant monopole and quadrupole excitations for
$^{120}$Sn and $^{208}$Pb at zero and finite temperatures are calculated within
Thomas-Fermi approximation by employing the microscopic in-medium
cross-sections of Li and Machleidt and the phenomenological Skyrme and Gogny
forces, and are compared with each other. The results for the collisional
widths of giant monopole and quadrupole vibrations at zero temperature as a
function of the mass number show that the collisional damping of giant monopole
vibrations accounts for about 30-40% of the observed widths at zero
temperature, while for giant quadrupole vibrations it accounts for only 20-30%
of the observed widths of zero temperature.",0101016v1
1996-12-08,Towards a Simple Model of Compressible Alfvenic Turbulence,"A simple model collisionless, dissipative, compressible MHD (Alfvenic)
turbulence in a magnetized system is investigated. In contrast to more familiar
paradigms of turbulence, dissipation arises from Landau damping, enters via
nonlinearity, and is distributed over all scales. The theory predicts that two
different regimes or phases of turbulence are possible, depending on the ratio
of steepening to damping coefficient (m_1/m_2). For strong damping
(|m_1/m_2|<1), a regime of smooth, hydrodynamic turbulence is predicted. For
|m_1/m_2|>1, steady state turbulence does not exist in the hydrodynamic limit.
Rather, spikey, small scale structure is predicted.",9612005v2
1998-10-01,Mode-coupling and nonlinear Landau damping effects in auroral Farley-Buneman turbulence,"The fundamental problem of Farley-Buneman turbulence in the auroral
$E$-region has been discussed and debated extensively in the past two decades.
In the present paper we intend to clarify the different steps that the auroral
$E$-region plasma has to undergo before reaching a steady state. The
mode-coupling calculation, for Farley-Buneman turbulence, is developed in order
to place it in perspective and to estimate its magnitude relative to the
anomalous effects which arise through the nonlinear wave-particle interaction.
This nonlinear effect, known as nonlinear ``Landau damping'' is due to the
coupling of waves which produces other waves which in turn lose energy to the
bulk of the particles by Landau damping. This leads to a decay of the wave
energy and consequently a heating of the plasma. An equation governing the
evolution of the field spectrum is derived and a physical interpration for each
of its terms is provided.",9810062v1
2000-08-20,Fabrication and Tolerance Issues and their Influence on Multi-Bunch Bbu and Emittance Dilution in the Construction of X-Band RDDS Linacs for the NLC,"The main linacs of the Next Linear Collider (NLC) will contain several
thousand X-band RDDS (Rounded Damped Detuned Structures). The transverse
wakefield in the structures is reduced by detuning the modal frequencies such
that they destructively interfere and by four damping manifolds per structure
which provide weak damping. Errors in the fabrication of the individual cells
and in the alignment of the cells will reduce the cancellation of the modes.
Here, we calculate the tolerances on random errors in the synchronous
frequencies of the cells and the cell-to-cell alignment.",0008198v1
2003-09-17,A New Damping Mechanism in Non-linear Bubble Dynamics,"Non-linear equations of radial motion of a gas bubble in a compressible
viscous liquid have been modified considering effects of viscosity and
compressibility more complete than all previous works. A new set of equations
has been derived including new terms resulted from consideration of the
viscosity and compressibility not only at the bubble interface, but also in the
bulk of liquid. The new equations are two non-linear coupled equations, which
can not be merged into one equation unlike all previously derived equations.
Numerical calculations have been performed considering effects of heat and mass
transfer at the bubble interface. The results indicate that the new terms
exhibit an important damping role at the collapse, so that their consideration
dramatically weakens the bubble rebounds after the collapse. Dependence of this
new damping mechanism to amplitude and frequency of the deriving pressure has
been investigated.",0309080v1
2003-11-26,Eigenvector Expansion and Petermann Factor for Ohmically Damped Oscillators,"Correlation functions $C(t) \sim <\phi(t)\phi(0)>$ in ohmically damped
systems such as coupled harmonic oscillators or optical resonators can be
expressed as a single sum over modes $j$ (which are not power-orthogonal), with
each term multiplied by the Petermann factor (PF) $C_j$, leading to ""excess
noise"" when $|C_j| > 1$. It is shown that $|C_j| > 1$ is common rather than
exceptional, that $|C_j|$ can be large even for weak damping, and that the PF
appears in other processes as well: for example, a time-independent
perturbation $\sim\ep$ leads to a frequency shift $\sim \ep C_j$. The
coalescence of $J$ ($>1$) eigenvectors gives rise to a critical point, which
exhibits ""giant excess noise"" ($C_j \to \infty$). At critical points, the
divergent parts of $J$ contributions to $C(t)$ cancel, while time-independent
perturbations lead to non-analytic shifts $\sim \ep^{1/J}$.",0311127v2
2004-04-02,DAFNE injection system upgrade,"High luminosity in DAFNE needs very high electron and positron currents
stored. A full energy (510 MeV) injection system composed by a full energy
electron and positron linac and an accumulator-damping ring is presently used.
The electron and positron beams, alternatively accelerated by the linac, are
injected and stacked in the accumulator with high efficiency thanks to its
large acceptance and short damping time. The damped beams are extracted and
transferred to the main ring through a long transfer line that has been built
inside already existing buildings. The refill time of the collider is limited
by the transfer line set-up change between the two different beams modes. In
this paper a transfer line modification is proposed in order to reduce the
switch time. A possible injection scheme for the main rings is also described.",0404010v1
2004-05-05,Langmuir wave self-focusing versus decay instability,"Electron trapping in a finite amplitude Langmuir wave (LW) leads to a
frequency shift, \Delta\omega_{TP} < 0, and reduced Landau damping. These may
lead to modulational instability. Its growth rate and damping threshold, due to
escape of trapped electrons at rate \nu, are calculated for the first time in
the short wavelength regime. If the background plasma is in thermal
equilibrium, it is shown that this trapped particle modulational instability
(TPMI) is not possible when k \lambda_D > 0.46, while for 0.33 < k \lambda_D <
0.46, TPMI requires that the fluctuation wavevector have a component
perpendicular to k, the LW wavevector, with \lambda_D the electron Debye
length. Its nonlinear evolution leads to self-focusing. Comparison is made with
a re-evaluated LW ion acoustic decay instability (LDI): compared to classical
estimates, the new LDI threshold is lowered by primary LW \Delta\omega_{TP}
since frequency matching leads to wavenumber and hence damping reduction of the
daughter LW. For parameters estimates relevant to a recent stimulated Raman
scatter experiment (Kline et al., submitted to PRL), the LDI and TPMI
thresholds cross in the range 0.28 < k \lambda_D < 0.34, consistent with the
observed LDI regime change. However, if \nu exceeds a critical value, estimated
to be order 1% of the electron plasma frequency, then TPMI is not possible at
any wavenumber.",0405015v1
2005-06-16,Mesoscale Quantization and Self-Organized Stability,"In the world of technology, one of the most important forms of friction is
that of rolling friction. Yet it is one of the least studied of all the known
forms of energy dissipation. In the present experiments we investigate the
oscillatory free-decay of a rigid cube, whose side-length is less than the
diameter of the rigid cylinder on which it rests. The resulting free-decay is
one of harmonic motion with damping. The non-dissipative character of the
oscillation yields to a linear differential equation; however, the damping is
found to involve more than a deterministic nonlinearity. Dominated by rolling
friction, the damping is sensitive to the material properties of the contact
surfaces. For `clean' surfaces of glass on glass, the decay shows features of
mesoscale quantization and self-organized stability.",0506143v1
2006-10-31,Ultimate parameters of the photon collider at the ILC,"At linear colliders, the e+e- luminosity is limited by beam-collision
effects, which determine the required emittances of beams in damping rings
(DRs). While in gamma-gamma collisions at the photon collider, these effects
are absent, and so smaller emittances are desirable. In present damping rings
designs, nominal DR parameters correspond to those required for e+e-
collisions. In this note, I would like to stress once again that as soon as we
plan the photon-collider mode of ILC operation, the damping-ring emittances are
dictated by the photon-collider requirements--namely, they should be as small
as possible. This can be achieved by adding more wigglers to the DRs; the
incremental cost is easily justified by a considerable potential improvement of
the gamma-gamma luminosity. No expert analysis exists as of yet, but it seems
realistic to obtain a factor five increase of the gamma-gamma luminosity
compared to the ``nominal'' DR design.",0610285v1
2006-04-27,On the weak solutions of the McKendrick equation: Existence of demography cycles,"We develop the qualitative theory of the solutions of the McKendrick partial
differential equation of population dynamics. We calculate explicitly the weak
solutions of the McKendrick equation and of the Lotka renewal integral equation
with time and age dependent birth rate. Mortality modulus is considered age
dependent. We show the existence of demography cycles. For a population with
only one reproductive age class, independently of the stability of the weak
solutions and after a transient time, the temporal evolution of the number of
individuals of a population is always modulated by a time periodic function.
The periodicity of the cycles is equal to the age of the reproductive age
class, and a population retains the memory from the initial data through the
amplitude of oscillations. For a population with a continuous distribution of
reproductive age classes, the amplitude of oscillation is damped. The
periodicity of the damped cycles is associated with the age of the first
reproductive age class. Damping increases as the dispersion of the fertility
function around the age class with maximal fertility increases. In general, the
period of the demography cycles is associated with the time that a species
takes to reach the reproductive maturity.",0604035v2
1999-03-05,Exact Diagonalization of Two Quantum Models for the Damped Harmonic Oscillator,"The damped harmonic oscillator is a workhorse for the study of dissipation in
quantum mechanics. However, despite its simplicity, this system has given rise
to some approximations whose validity and relation to more refined descriptions
deserve a thorough investigation. In this work, we apply a method that allows
us to diagonalize exactly the dissipative Hamiltonians that are frequently
adopted in the literature. Using this method we derive the conditions of
validity of the rotating-wave approximation (RWA) and show how this approximate
description relates to more general ones. We also show that the existence of
dissipative coherent states is intimately related to the RWA. Finally, through
the evaluation of the dynamics of the damped oscillator, we notice an important
property of the dissipative model that has not been properly accounted for in
previous works; namely, the necessity of new constraints to the application of
the factorizable initial conditions.",9903022v2
1999-04-06,Nonclassical correlations in damped quantum solitons,"Using cumulant expansion in Gaussian approximation, the internal quantum
statistics of damped soliton-like pulses in Kerr media are studied numerically,
considering both narrow and finite bandwidth spectral pulse components. It is
shown that the sub-Poissonian statistics can be enhanced, under certain
circumstances, by absorption, which damps out some destructive interferences.
Further, it is shown that both the photon-number correlation and the
correlation of the photon-number variance between different pulse components
can be highly nonclassical even for an absorbing fiber. Optimum frequency
windows are determined in order to realize strong nonclassical behavior, which
offers novel possibilities of using solitons in optical fibers as a source of
nonclassically correlated light beams.",9904017v2
1999-04-19,Quantum theory of fluctuations in a cold damped accelerometer,"We present a quantum network approach to real high sensitivity measurements.
Thermal and quantum fluctuations due to active as well as passive elements are
taken into account. The method is applied to the analysis of the capacitive
accelerometer using the cold damping technique, developed for fundamental
physics in space by ONERA and the ultimate limits of this instrument are
discussed. It is confirmed in this quantum analysis that the cold damping
technique allows one to control efficiently the test mass motion without
degrading the noise level.",9904073v2
2000-07-04,Stochastic limit approximation for rapidly decaying systems,"The stochastic limit approximation method for ``rapid'' decay is presented,
where the damping rate \gamma is comparable to the system frequency \Omega,
i.e., \gamma \sim \Omega, whereas the usual stochastic limit approximation is
applied only to the weak damping situation \gamma << \Omega. The key formulas
for rapid decay are very similar to those for weak damping, but the dynamics is
quite different. From a microscopic Hamiltonian, the spin-boson model, a Bloch
equation containing two independent time scales is derived. This is a useful
method to extract the minimal dissipative dynamics at high temperature kT >>
\hbar\Omega and the master equations obtained are of the Lindblad form even for
the Caldeira-Leggett model. The validity of the method is confirmed by
comparing the master equation derived through this method with the exact one.",0007007v2
2000-08-01,Full mechanical characterization of a cold damped mirror,"We describe an experiment in which we have used a cold damping feedback
mechanism to reduce the thermal noise of a mirror around its mechanical
resonance frequency. The monitoring of the brownian motion of the mirror allows
to apply an additional viscous force without any thermal fluctuations
associated. This scheme has been experimentally implemented with the radiation
pressure of an intensity-modulated laser beam. Large noise reductions, up to 30
dB, have been obtained. We have also checked the mechanical response of the
cold damped mirror, and monitored its transient evolution between the cooled
regime and the room temperature equilibrium. A simple theoretical model allows
to fully explain the experimental results. A possible application to the active
cooling of the violin modes in a gravitational-wave interferometer is
discussed.",0008004v1
2003-11-05,Exact decoherence to pointer states in free open quantum systems is universal,"In this paper it is shown that exact decoherence to minimal uncertainty
Gaussian pointer states is generic for free quantum particles coupled to a heat
bath. More specifically, the paper is concerned with damped free particles
linearly coupled under product initial conditions to a heat bath at arbitrary
temperature, with arbitrary coupling strength and spectral densities covering
the Ohmic, subohmic, and supraohmic regime. Then it is true that there exists a
time t_c such that for times t>t_c the state can always be exactly represented
as a mixture (convex combination) of particular minimal uncertainty Gaussian
states, regardless of and independent from the initial state. This exact
`localisation' is hence not a feature specific to high temperatures and weak
damping limit, but is rather a generic property of damped free particles.",0311022v3
2004-07-30,Kraus representation of damped harmonic oscillator and its application,"By definition, the Kraus representation of a harmonic oscillator suffering
from the environment effect, modeled as the amplitude damping or the phase
damping, is directly given by a simple operator algebra solution. As examples
and applications, we first give a Kraus representation of a single qubit whose
computational basis states are defined as bosonic vacuum and single particle
number states. We further discuss the environment effect on qubits whose
computational basis states are defined as the bosonic odd and even coherent
states. The environment effects on entangled qubits defined by two different
kinds of computational basis are compared with the use of fidelity.",0407263v2
2005-01-31,"The non dissipative damping of the Rabi oscillations as a ""which-path"" information","Rabi oscillations may be viewed as an interference phenomenon due to a
coherent superposition of different quantum paths, like in the Young's two-slit
experiment. The inclusion of the atomic external variables causes a non
dissipative damping of the Rabi oscillations. More generally, the atomic
translational dynamics induces damping in the correlation functions which
describe non classical behaviors of the field and internal atomic variables,
leading to the separability of these two subsystems. We discuss on the
possibility of interpreting this intrinsic decoherence as a ""which-way""
information effect and we apply to this case a quantitative analysis of the
complementarity relation as introduced by Englert [Phys. Rev. Lett.
\textbf{77}, 2154 (1996)].",0501181v1
2006-01-12,Driven harmonic oscillator as a quantum simulator for open systems,"We show theoretically how a driven harmonic oscillator can be used as a
quantum simulator for non-Markovian damped harmonic oscillator. In the general
framework, the results demonstrate the possibility to use a closed system as a
simulator for open quantum systems. The quantum simulator is based on sets of
controlled drives of the closed harmonic oscillator with appropriately tailored
electric field pulses. The non-Markovian dynamics of the damped harmonic
oscillator is obtained by using the information about the spectral density of
the open system when averaging over the drives of the closed oscillator. We
consider single trapped ions as a specific physical implementation of the
simulator, and we show how the simulator approach reveals new physical insight
into the open system dynamics, e.g. the characteristic quantum mechanical
non-Markovian oscillatory behavior of the energy of the damped oscillator,
usually obtained by the non-Lindblad-type master equation, can have a simple
semiclassical interpretation.",0601081v2
2006-07-31,Nonadiabatic Transitions for a Decaying Two-Level-System: Geometrical and Dynamical Contributions,"We study the Landau-Zener Problem for a decaying two-level-system described
by a non-hermitean Hamiltonian, depending analytically on time. Use of a
super-adiabatic basis allows to calculate the non-adiabatic transition
probability P in the slow-sweep limit, without specifying the Hamiltonian
explicitly. It is found that P consists of a ``dynamical'' and a
``geometrical'' factors. The former is determined by the complex adiabatic
eigenvalues E_(t), only, whereas the latter solely requires the knowledge of
\alpha_(+-)(t), the ratio of the components of each of the adiabatic
eigenstates. Both factors can be split into a universal one, depending only on
the complex level crossing points, and a nonuniversal one, involving the full
time dependence of E_(+-)(t). This general result is applied to the
Akulin-Schleich model where the initial upper level is damped with damping
constant $\gamma$. For analytic power-law sweeps we find that Stueckelberg
oscillations of P exist for gamma smaller than a critical value gamma_c and
disappear for gamma > gamma_c. A physical interpretation of this behavior will
be presented by use of a damped harmonic oscillator.",0607221v1
2007-05-05,Damped Corrections to Inflationary Spectra from a Fluctuating Cutoff,"We reconsider trans-Planckian corrections to inflationary spectra by taking
into account a physical effect which has been overlooked and which could have
important consequences. We assume that the short length scale characterizing
the new physics is endowed with a finite width, the origin of which could be
found in quantum gravity. As a result, the leading corrections responsible for
superimposed osillations in the CMB temperature anisotropies are generically
damped by the blurring of the UV scale. To determine the observational
ramifications of this damping, we compare it to that which effectively occurs
when computing the angular power spectrum of temperature anisotropies. The
former gives an overall change of the oscillation amplitudes whereas the latter
depends on the angular scale. Therefore, in principle they could be
distinguished. In any case, the observation of superimposed oscillations would
place tight constraint on the variance of the UV cutoff.",0705.0747v1
2007-05-10,Effective temperature and Gilbert damping of a current-driven localized spin,"Starting from a model that consists of a semiclassical spin coupled to two
leads we present a microscopic derivation of the Langevin equation for the
direction of the spin. For slowly-changing direction it takes on the form of
the stochastic Landau-Lifschitz-Gilbert equation. We give expressions for the
Gilbert damping parameter and the strength of the fluctuations, including their
bias-voltage dependence. At nonzero bias-voltage the fluctuations and damping
are not related by the fluctuation-dissipation theorem. We find, however, that
in the low-frequency limit it is possible to introduce a voltage-dependent
effective temperature that characterizes the fluctuations in the direction of
the spin, and its transport-steady-state probability distribution function.",0705.1432v3
2007-05-10,Magnetization oscillations induced by a spin-polarized current in a point-contact geometry: mode hopping and non-linear damping effects,"In this paper we study magnetization excitations induced in a thin extended
film by a spin-polarized dc-current injected through a point contact in the
current-perpendicular-to-plane (CPP) geometry. Using full-scale micromagnetic
simulations, we demonstrate that in addition to the oscillations of the
propagating wave type, there exist also two localized oscillation modes. The
first localized mode has a relatively homogeneous magnetization structure of
its kernel and corresponds to the so called 'bullet' predicted analytically by
Slavin and Tiberkevich (Phys. Rev. Lett., 95 (2005) 237201). Magnetization
pattern of the second localized mode kernel is highly inhomogeneous, leading to
a much smaller power of magnetoresistance oscillations caused by this mode. We
have also studied the influence of a non-linear damping for this system and
have found the following main qualitative effects: (i) the appearance of
frequency jumps within the existence region of the propagating wave mode and
(ii) the narrowing of the current region where the 'bullet' mode exists, until
this mode completely disappears for a sufficiently strong non-linear damping.",0705.1515v1
2007-05-27,Amplitude Damping for single-qubit System with single-qubit mixed-state Environment,"We study a generalized amplitude damping channel when environment is
initially in the single-qubit mixed state. Representing the affine
transformation of the generalized amplitude damping by a three-dimensional
volume, we plot explicitly the volume occupied by the channels simulatable by a
single-qubit mixed-state environment. As expected, this volume is embedded in
the total volume by the channels which is simulated by two-qubit enviroment.
The volume ratio is approximately 0.08 which is much smaller than 3/8, the
volume ratio for generalized depolarizing channels.",0705.3952v3
2007-06-01,The geometrical quantity in damped wave equations on a square,"The energy in a square membrane $\Omega$ subject to constant viscous damping
on a subset $\omega\subset \Omega$ decays exponentially in time as soon as
$\omega$ satisfies a geometrical condition known as the ""Bardos-Lebeau-Rauch""
condition. The rate $\tau(\omega)$ of this decay satisfies $\tau(\omega)= 2
\min(-\mu(\omega), g(\omega))$ (see Lebeau [Math. Phys. Stud. 19 (1996)
73-109]). Here $\mu(\omega)$ denotes the spectral abscissa of the damped wave
equation operator and $g(\omega)$ is a number called the geometrical quantity
of $\omega$ and defined as follows. A ray in $\Omega$ is the trajectory
generated by the free motion of a mass-point in $\Omega$ subject to elastic
reflections on the boundary. These reflections obey the law of geometrical
optics. The geometrical quantity $g(\omega)$ is then defined as the upper limit
(large time asymptotics) of the average trajectory length. We give here an
algorithm to compute explicitly $g(\omega)$ when $\omega$ is a finite union of
squares.",0706.0172v1
2007-06-08,Kinetic-Ion Simulations Addressing Whether Ion Trapping Inflates Stimulated Brillouin Backscattering Reflectivities,"An investigation of the possible inflation of stimulated Brillouin
backscattering (SBS) due to ion kinetic effects is presented using
electromagnetic particle simulations and integrations of three-wave
coupled-mode equations with linear and nonlinear models of the nonlinear ion
physics. Electrostatic simulations of linear ion Landau damping in an ion
acoustic wave, nonlinear reduction of damping due to ion trapping, and
nonlinear frequency shifts due to ion trapping establish a baseline for
modeling the electromagnetic SBS simulations. Systematic scans of the laser
intensity have been undertaken with both one-dimensional particle simulations
and coupled-mode-equations integrations, and two values of the electron-to-ion
temperature ratio (to vary the linear ion Landau damping) are considered. Three
of the four intensity scans have evidence of SBS inflation as determined by
observing more reflectivity in the particle simulations than in the
corresponding three-wave mode-coupling integrations with a linear ion-wave
model, and the particle simulations show evidence of ion trapping.",0706.1236v1
2007-06-29,Driving-dependent damping of Rabi oscillations in two-level semiconductor systems,"We propose a mechanism to explain the nature of the damping of Rabi
oscillations with increasing driving-pulse area in localized semiconductor
systems, and have suggested a general approach which describes a coherently
driven two-level system interacting with a dephasing reservoir. Present
calculations show that the non-Markovian character of the reservoir leads to
the dependence of the dephasing rate on the driving-field intensity, as
observed experimentally. Moreover, we have shown that the damping of Rabi
oscillations might occur as a result of different dephasing mechanisms for both
stationary and non-stationary effects due to coupling to the environment.
Present calculated results are found in quite good agreement with available
experimental measurements.",0706.4372v1
2007-08-06,Collisionsless amplifying of longitudinal electron waves in two-stream plasma,"To better understanding the principal features of collisionless
damping/growing plasma waves we have implemented a demonstrative calculation
for the simplest cases of electron waves in two-stream plasmas with the
delta-function type electron velocity distribution function of each of the
streams with velocities v(1) and v(2). The traditional dispersion equation is
reduced to an algebraic 4th order equation, for which numerical solutions are
presented for a variant of equal stream densities. In the case of uniform
half-infinite slab one finds two dominant type solutions: non-damping forward
waves and forward complex conjugated exponentially both damping and growing
waves. Beside it in this case there is no necessity of calculation any
logarithmically divergent indefinite integrals. The possibility of wave
amplifying might be useful in practical applications.",0708.0767v1
2007-08-09,The Highly Damped Quasinormal Modes of Extremal Reissner-Nordström and Reissner-Nordström-de Sitter Black Holes,"We analyze in detail the highly damped quasinormal modes of $D$-dimensional
extremal Reissner-Nordstr$\ddot{\rm{o}}$m and
Reissner-Nordstr$\ddot{\rm{o}}$m-de Sitter black holes. We only consider the
extremal case where the event horizon and the Cauchy inner horizon coincide. We
show that, even though the topology of the Stokes/anti-Stokes lines in the
extremal case is different than the non-extremal case, the highly damped
quasinormal mode frequencies of extremal black holes match exactly with the
extremal limit of the non-extremal black hole quasinormal mode frequencies.",0708.1333v2
2007-08-28,Resonantly damped surface and body MHD waves in a solar coronal slab with oblique propagation,"The theory of magnetohydrodynamic (MHD) waves in solar coronal slabs in a
zero-$\beta$ configuration and for parallel propagation of waves does not allow
the existence of surface waves. When oblique propagation of perturbations is
considered both surface and body waves are able to propagate. When the
perpendicular wave number is larger than a certain value, the body kink mode
becomes a surface wave. In addition, a sausage surface mode is found below the
internal cut-off frequency. When non-uniformity in the equilibrium is included,
surface and body modes are damped due to resonant absorption. In this paper,
first, a normal-mode analysis is performed and the period, the damping rate,
and the spatial structure of eigenfunctions are obtained. Then, the
time-dependent problem is solved, and the conditions under which one or the
other type of mode is excited are investigated.",0708.3783v1
2007-09-11,Teleportation of qubit states through dissipative channels: Conditions for surpassing the no-cloning limit,"We investigate quantum teleportation through dissipative channels and
calculate teleportation fidelity as a function of damping rates. It is found
that the average fidelity of teleportation and the range of states to be
teleported depend on the type and rate of the damping in the channel. Using the
fully entangled fraction, we derive two bounds on the damping rates of the
channels: one is to beat the classical limit and the second is to guarantee the
non-existence of any other copy with better fidelity. Effect of the initially
distributed maximally entangled state on the process is presented; and the
concurrence and the fully entangled fraction of the shared states are
discussed. We intend to show that prior information on the dissipative channel
and the range of qubit states to be teleported is helpful for the evaluation of
the success of teleportation, where success is defined as surpassing the
fidelity limit imposed by the fidelity of 1-to-2 optimal cloning machine for
the specific range of qubits.",0709.1662v1
2007-10-03,Global stability of travelling fronts for a damped wave equation with bistable nonlinearity,"We consider the damped wave equation \alpha u_tt + u_t = u_xx - V'(u) on the
whole real line, where V is a bistable potential. This equation has travelling
front solutions of the form u(x,t) = h(x-st) which describe a moving interface
between two different steady states of the system, one of which being the
global minimum of V. We show that, if the initial data are sufficiently close
to the profile of a front for large |x|, the solution of the damped wave
equation converges uniformly on R to a travelling front as t goes to plus
infinity. The proof of this global stability result is inspired by a recent
work of E. Risler and relies on the fact that our system has a Lyapunov
function in any Galilean frame.",0710.0794v1
2007-12-19,Cosmic String Dynamics and Evolution in Warped Spacetime,"We study the dynamics and evolution of Nambu-Goto strings in a warped
spacetime, where the warp factor is a function of the internal coordinates
giving rise to a `throat' region. The microscopic equations of motion for
strings in this background include potential and friction terms, which attract
the strings towards the bottom of the warping throat. However, by considering
the resulting macroscopic equations for the velocities of strings in the
vicinity of the throat, we note the absence of enough classical damping to
guarantee that the strings actually reach the warped minimum and stabilise
there. Instead, our classical analysis supports a picture in which the strings
experience mere deflections and bounces around the tip, rather than strongly
damped oscillations. Indeed, 4D Hubble friction is inefficient in the internal
dimensions and there is no other classical mechanism known, which could provide
efficient damping. These results have potentially important implications for
the intercommuting probabilities of cosmic superstrings.",0712.3224v2
2007-12-20,The Critical Exponent of the Fractional Langevin Equation is $α_c\approx 0.402$,"We investigate the dynamical phase diagram of the fractional Langevin
equation and show that critical exponents mark dynamical transitions in the
behavior of the system. For a free and harmonically bound particle the critical
exponent $\alpha_c= 0.402\pm 0.002$ marks a transition to a non-monotonic
under-damped phase. The critical exponent $\alpha_{R}=0.441...$ marks a
transition to a resonance phase, when an external oscillating field drives the
system. Physically, we explain these behaviors using a cage effect, where the
medium induces an elastic type of friction. Phase diagrams describing the
under-damped, the over-damped and critical frequencies of the fractional
oscillator, recently used to model single protein experiments, show behaviors
vastly different from normal.",0712.3407v1
2008-01-24,Particle Acceleration by Fast Modes in Solar Flares,"We address the problem of particle acceleration in solar flares by fast modes
which may be excited during the reconnection and undergo cascade and are
subjected to damping. We extend the calculations beyond quasilinear
approximation and compare the acceleration and scattering by transit time
damping and gyroresonance interactions. We find that the acceleration is
dominated by the so called transit time damping mechanism. We estimate the
total energy transferred into particles, and show that our approach provides
sufficiently accurate results We compare this rate with energy loss rate.
Scattering by fast modes appears to be sufficient to prevent the protons from
escaping the system during the acceleration. Confinement of electrons, on the
other hand, requires the existence of plasma waves. Electrons can be
accelerated to GeV energies through the process described here for solar flare
conditions.",0801.3786v2
2008-02-07,Analysis of squeal noise and mode coupling instabilities including damping and gyroscopic effects,"This paper deals with an audible disturbance known as automotive clutch
squeal noise from the viewpoint of friction-induced mode coupling instability.
Firstly, an auto-coupling model is presented showing a non-conservative
circulatory effect originating from friction forces. Secondly, the stability of
an equilibrium is investigated by determining the eigenvalues of the system
linearized equations. The effects of the circulatory and gyroscopic actions are
examined analytically and numerically to determine their influence on the
stability region. Separate and combined effects are analysed with and without
structural damping and important information is obtained on the role of each
parameter and their interactions regarding overall stability. Not only is
structural damping shown to be of primary importance, as reported in many
previous works, this article also highlights a particular relationship with
gyroscopic effects. A method of optimizing both the stability range and its
robustness with respect to uncertainty on system parameters is discussed after
which practical design recommendations are given.",0802.0923v1
2008-02-12,Nonlinear Saturation of g-modes in Proto-Neutron Stars: Quieting the Acoustic Engine,"According to Burrows et al.'s acoustic mechanism for core-collapse supernova
explosions, the primary, l=1, g-mode in the core of the proto-neutron star is
excited to an energy of ~ 10^{50} ergs and damps by the emission of sound
waves. Here we calculate the damping of the primary mode by the parametric
instability, i.e., by nonlinear, 3-mode coupling between the low-order primary
mode and pairs of high-order g-modes. We show that the primary mode is strongly
coupled to highly resonant, neutrino damped pairs with n>10; such short
wavelength interactions cannot be resolved in the simulations. We find that the
parametric instability saturates the primary mode energy at ~10^{48} ergs, well
below the energy needed to drive an explosion. We therefore conclude that
acoustic power is unlikely to be energetically significant in core-collapse
supernova explosions.",0802.1522v3
2008-02-21,Gas Damping Coefficient Research for MEMS Comb Linear Vibration Gyroscope,"Silicon-MEMS gyroscope is an important part of MEMS (Micro Electrical
Mechanical System). There are some disturb ignored in traditional gyroscope
that must be evaluated newly because of its smaller size (reach the level of
micron). In these disturb, the air pressure largely influences the performance
of MEMS gyroscope. Different air pressure causes different gas damping
coefficient for the MEMS comb linear vibration gyroscope and different gas
damping coefficient influences the quality factor of the gyroscope directive.
The quality factor influences the dynamic working bandwidth of the MEMS comb
linear vibration gyroscope, so it is influences the output characteristic of
the MEMS comb linear vibration gyroscope. The paper shows the relationship
between the air pressure and the output amplified and phase of the detecting
axis through analyzing the air pressure influence on the MEMS comb linear
vibration gyroscope. It discusses the influence on the frequency distribute and
quality factor of the MEMS comb linear vibration gyroscope for different air
pressure.",0802.3048v1
2008-03-03,Damped harmonic oscillator interpretation of the soft-state power spectra of Cyg X-1,"We develop a model of an accretion disc in which the variability induced at a
given radius is governed by a damped harmonic oscillator at the corresponding
epicyclic frequency. That variability induces both linear and non-linear
responses in the locally emitted radiation. The total observed variability of a
source is the sum of these contributions over the disc radius weighted by the
energy dissipation rate at each radius. It is shown that this simple model,
which effectively has only three parameters including the normalization, can
explain the range of the power spectra observed from Cyg X-1 in the soft state.
Although a degeneracy between the black hole mass and the strength of the
damping does not allow a unique determination of the mass, we can still
constrain it to <16--20 solar masses. We also show that our model preserves the
observed linear rms-flux relationship even in the presence of the non-linear
flux response.",0803.0238v2
2008-03-05,The Secular Evolution of a Close Ring-Satellite System: The Excitation of Spiral Density Waves at a Nearby Gap Edge,"The Lagrange planetary equations are used to study to secular evolution of a
small, eccentric satellite that orbits within a narrow gap in a broad,
self-gravitating planetary ring. These equations show that the satellite's
secular perturbations of the ring will excite a very long-wavelength spiral
density wave that propagates away from the gap's outer edge. The amplitude of
these waves, as well as their dispersion relation, are derived here. That
dispersion relation reveals that a planetary ring can sustain two types of
density waves: long waves that, in Saturn's A ring, would have wavelengths of
order 100 km, and short waves that tend to be very nonlinear and are expected
to quickly damp. The excitation of these waves also transports angular momentum
from the ring to the satellite in a way that damps the satellite's eccentricity
e, which also tends to reduce the amplitude of subsequent waves. The rate of
eccentricity damping due to this wave action is then compared to the rates at
which the satellite's Lindblad and corotation resonances alter the satellite's
e. These results are then applied to the gap-embedded Saturnian satellites Pan
and Daphnis, and the long-term stability of their eccentricities is assessed.",0803.0576v1
2008-03-06,Hypersound damping in vitreous silica measured by picosecond acoustics,"The attenuation of longitudinal acoustic phonons up to frequencies nearing
250 GHz is measured in vitreous silica with a picosecond optical technique.
Taking advantage of interferences on the probe beam, difficulties encountered
in early pioneering experiments are alleviated. Sound damping at 250 GHz and
room temperature is consistent with relaxation dominated by anharmonic
interactions with the thermal bath, extending optical Brillouin scattering
data. Our result is at variance with claims of a recent deep-UV experiment
which reported a rapid damping increase beyond 100 GHz. A comprehensive picture
of the frequency dependence of sound attenuation in $v$-SiO$_2$ can be
proposed.",0803.0832v1
2008-03-07,Resonance distribution in open quantum chaotic systems,"In order to study the resonance spectra of chaotic cavities subject to some
damping (which can be due to absorption or partial reflection at the
boundaries), we use a model of damped quantum maps. In the high-frequency
limit, the distribution of (quantum) decay rates is shown to cluster near a
``typical'' value, which is larger than the classical decay rate of the
corresponding damped ray dynamics. The speed of this clustering may be quite
slow, which could explain why it has not been detected in previous numerical
data.",0803.1075v4
2008-04-03,Single flux quantum circuits with damping based on dissipative transmission lines,"We propose and demonstrate the functioning of a special Rapid Single Flux
Quantum (RSFQ) circuit with frequency-dependent damping. This damping is
achieved by shunting individual Josephson junctions by pieces of open-ended RC
transmission lines. Our circuit includes a toggle flip-flop cell, Josephson
transmission lines transferring single flux quantum pulses to and from this
cell, as well as DC/SFQ and SFQ/DC converters. Due to the desired
frequency-dispersion in the RC line shunts which ensures sufficiently low noise
at low frequencies, such circuits are well-suited for integrating with the
flux/phase Josephson qubit and enable its efficient control.",0804.0442v1
2008-05-14,"Reconciling results of LSND, MiniBooNE and other experiments with soft decoherence","We propose an explanation of the LSND signal via quantum-decoherence of the
mass states, which leads to damping of the interference terms in the
oscillation probabilities. The decoherence parameters as well as their energy
dependence are chosen in such a way that the damping affects only oscillations
with the large (atmospheric) $\Delta m^2$ and rapidly decreases with the
neutrino energy. This allows us to reconcile the positive LSND signal with
MiniBooNE and other null-result experiments. The standard explanations of
solar, atmospheric, KamLAND and MINOS data are not affected. No new particles,
and in particular, no sterile neutrinos are needed. The LSND signal is
controlled by the 1-3 mixing angle $\theta_{13}$ and, depending on the degree
of damping, yields $0.0014 < \sin^2\theta_{13} < 0.034$ at $3\sigma$. The
scenario can be tested at upcoming $\theta_{13}$ searches: while the comparison
of near and far detector measurements at reactors should lead to a null-result
a positive signal for $\theta_{13}$ is expected in long-baseline accelerator
experiments. The proposed decoherence may partially explain the results of
Gallium detector calibrations and it can strongly affect supernova neutrino
signals.",0805.2098v1
2008-06-02,Observations of Solar Doppler Shift Oscillations with the EUV Imaging Spectrometer on Hinode,"Damped Doppler shift oscillations have been observed in emission lines from
ions formed at flare temperatures with the Solar Ultraviolet Measurements of
Emitted Radiation spectrometer on the Solar and Heliospheric Observatory and
with the Bragg Crystal Spectrometer on Yohkoh. This Letter reports the
detection of low-amplitude damped oscillations in coronal emission lines formed
at much lower temperatures observed with the EUV Imaging Spectrometer on the
Hinode satellite. The oscillations have an amplitude of about 2 km/s, and a
period of around 35 min. The decay times show some evidence for a temperature
dependence with the lowest temperature of formation emission line (Fe XII
195.12 Angstroms) exhibiting a decay time of about 43 min, while the highest
temperature of formation emission line (Fe XV 284.16 Angstroms) shows no
evidence for decay over more than two periods of the oscillation. The data
appear to be consistent with slow magnetoacoustic standing waves, but may be
inconsistent with conductive damping.",0806.0265v1
2008-08-01,Field-Driven Domain-Wall Dynamics in GaMnAs Films with Perpendicular Anisotropy,"We combine magneto-optical imaging and a magnetic field pulse technique to
study domain wall dynamics in a ferromagnetic (Ga,Mn)As layer with
perpendicular easy axis. Contrary to ultrathin metallic layers, the depinning
field is found to be smaller than the Walker field, thereby allowing for the
observation of the steady and precessional flow regimes. The domain wall width
and damping parameters are determined self-consistently. The damping, 30 times
larger than the one deduced from ferromagnetic resonance, is shown to
essentially originate from the non-conservation of the magnetization modulus.
An unpredicted damping resonance and a dissipation regime associated with the
existence of horizontal Bloch lines are also revealed.",0808.0119v1
2008-08-11,Effect of frequency and temperature on microwave-induced magnetoresistance oscillations in two-dimensional electron systems,"Experimental results on microwave-induced magnetoresistance oscillation in
two-dimensional electron systems show a similar behavior of these systems
regarding temperature and microwave frequency. It is found that these
oscillations tend to quench when frequency or temperature increase, approaching
magnetoresistance to the response of the dark system. In this work we show that
this experimental behavior can be addressed on the same theoretical basis.
Microwave radiation forces the electron orbits to move back and forth being
damped by interaction with the lattice. We show that this damping depends
dramatically on microwave frequency and also on temperature. An increase in
frequency or temperature gives rise to an increase in the lattice damping
producing eventually a quenching effect in the magnetoresistance oscillations.",0808.1489v1
2008-09-26,Damping and magnetic anisotropy of ferromagnetic GaMnAs thin films,"The magnetic properties of annealed, epitaxial Ga0.93Mn0.07As layers under
tensile and compressive stress have been investigated by X-band (9GHz) and
Q-band (35GHz) ferromagnetic resonance (FMR) spectroscopy. From the analysis of
the linewidths of the uniform mode spectra the FMR Gilbert damping factor
""alpha"" has been determined. At T=4K we obtain a minimum damping factor of
""alpha"" = 0.003 for the compressively stressed layer. Its value is not
isotropic. It has a minimum value for the easy axes orientations of the
magnetic field and increases with the measuring temperature. Its average value
is for both type of films of the order of 0.01 in spite of strong differences
in the inhomogeneous linewidth which vary between 20 Oe and 600 Oe for the
layers grown on GaAs and GaInAs substrates respectively.",0809.4644v2
2008-11-13,Higher order energy decay rates for damped wave equations with variable coefficients,"Under appropriate assumptions the energy of wave equations with damping and
variable coefficients $c(x)u_{tt}-\hbox{div}(b(x)\nabla u)+a(x)u_t =h(x)$ has
been shown to decay. Determining the rate of decay for the higher order
energies involving the $k$th order spatial and time derivatives has been an
open problem with the exception of some sparse results obtained for $k=1,2,3$.
We establish estimates that optimally relate the higher order energies with the
first order energy by carefully analyzing the effects of linear damping. The
results concern weighted (in time) and also pointwise (in time) energy decay
estimates. We also obtain $L^\infty$ estimates for the solution $u$. As an
application we compute explicit decay rates for all energies which involve the
dimension $n$ and the bounds for the coefficients $a(x)$ and $b(x)$ in the case
$c (x)=1$ and $h(x)=0.$",0811.2159v1
2009-01-12,Nonlinear Wigner solid transport over superfluid helium under AC conditions,"Nonlinear transport properties of the two-dimensional Wigner solid of surface
electrons on superfluid helium are studied for alternating current conditions.
For time-averaged quantities like Fourier coefficients, the field-velocity
characteristics are shown to be qualitatively different as compared to that
found in the DC theory. For a spatially uniform current we found a general
solution for the field-velocity relationship which appears to be strongly
dependent on the current frequency. If the current frequency is much lower than
the ripplon damping parameter, the Bragg-Cherenkov resonances which appear at
high enough drift velocities acquire a distinctive saw-tooth shape with long
right-side tails independent of small damping. For current frequencies which
are close or higher than the ripplon damping coefficient, the interference of
ripplons excited at different time intervals results in a new oscillatory (in
drift velocity) regime of Bragg-Cherenkov scattering.",0901.1508v1
2009-01-14,"Brownian motion with respect to time-changing Riemannian metrics, applications to Ricci flow","We generalize Brownian motion on a Riemannian manifold to the case of a
family of metrics which depends on time. Such questions are natural for
equations like the heat equation with respect to time dependent Laplacians
(inhomogeneous diffusions). In this paper we are in particular interested in
the Ricci flow which provides an intrinsic family of time dependent metrics. We
give a notion of parallel transport along this Brownian motion, and establish a
generalization of the Dohrn-Guerra or damped parallel transport, Bismut
integration by part formulas, and gradient estimate formulas. One of our main
results is a characterization of the Ricci flow in terms of the damped parallel
transport. At the end of the paper we give an intrinsic definition of the
damped parallel transport in terms of stochastic flows, and derive an intrinsic
martingale which may provide information about singularities of the flow.",0901.1999v2
2009-01-15,The sound damping constant for generalized theories of gravity,"The near-horizon metric for a black brane in Anti-de Sitter (AdS) space and
the metric near the AdS boundary both exhibit hydrodynamic behavior. We
demonstrate the equivalence of this pair of hydrodynamic systems for the sound
mode of a conformal theory. This is first established for Einstein's gravity,
but we then show how the sound damping constant will be modified, from its
Einstein form, for a generalized theory. The modified damping constant is
expressible as the ratio of a pair of gravitational couplings that are
indicative of the sound-channel class of gravitons. This ratio of couplings
differs from both that of the shear diffusion coefficient and the shear
viscosity to entropy ratio. Our analysis is mostly limited to conformal
theories but suggestions are made as to how this restriction might eventually
be lifted.",0901.2191v1
2009-01-26,Damping of sound waves in superfluid nucleon-hyperon matter of neutron stars,"We consider sound waves in superfluid nucleon-hyperon matter of massive
neutron-star cores. We calculate and analyze the speeds of sound modes and
their damping times due to the shear viscosity and non-equilibrium weak
processes of particle transformations. For that, we employ the dissipative
relativistic hydrodynamics of a superfluid nucleon-hyperon mixture, formulated
recently [M.E. Gusakov and E.M. Kantor, Phys. Rev. D78, 083006 (2008)]. We
demonstrate that the damping times of sound modes calculated using this
hydrodynamics and the ordinary (nonsuperfluid) one, can differ from each other
by several orders of magnitude.",0901.4108v1
2009-03-02,Attenuation and damping of electromagnetic fields: Influence of inertia and displacement current,"New results for attenuation and damping of electromagnetic fields in rigid
conducting media are derived under the conjugate influence of inertia due to
charge carriers and displacement current. Inertial effects are described by a
relaxation time for the current density in the realm of an extended Ohm's law.
The classical notions of poor and good conductors are rediscussed on the basis
of an effective electric conductivity, depending on both wave frequency and
relaxation time. It is found that the attenuation for good conductors at high
frequencies depends solely on the relaxation time. This means that the
penetration depth saturates to a minimum value at sufficiently high
frequencies. It is also shown that the actions of inertia and displacement
current on damping of magnetic fields are opposite to each other. That could
explain why the classical decay time of magnetic fields scales approximately as
the diffusion time. At very small length scales, the decay time could be given
either by the relaxation time or by a fraction of the diffusion time, depending
whether inertia or displacement current, respectively, would prevail on
magnetic diffusion.",0903.0210v1
2009-04-06,Scrutinizing single-qubit quantum channels: Theory and experiment with trapped ions,"We report experimental implementation of various types of qubit channels
using an individual trapped ion. We analyzed experimental data and we performed
tomographic reconstruction of quantum channels based on these data.
Specifically, we studied phase damping channels, where the damping acts either
in the xy-plane of the Bloch sphere or in an arbitrary plane that includes the
origin of the Bloch sphere. We also experimentally realized and consequently
analyzed quantum channels that in addition to phase damping affect also a
polarization rotation. We used three reconstruction schemes for estimation of
quantum channels from experimental data: (1) a linear inverse method, (2) a
maximum likelihood estimation, and (3) a constrained maximum likelihood
estimation. We took into account realistic experimental conditions where
imperfect test-state preparations and biased measurements are incorporated into
the estimation schemes. As a result we found that imperfections present in the
process of preparation of test states and as well as in measurements of the
considered ion trap system do not limit the control of the implementation of
the desired channel. Even imperfect preparation of test state and subsequent
measurements still provide sufficient resources for the complete
quantum-channel tomography.",0904.0923v1
2009-05-13,Time-dependent barrier passage of Two-dimensional non-Ohmic damping system,"The time-dependent barrier passage of an anomalous damping system is studied
via the generalized Langevin equation (GLE) with non-Ohmic memory damping
friction tensor and corresponding thermal colored noise tensor describing a
particle passing over the saddle point of a two-dimensional quadratic potential
energy surface. The time-dependent passing probability and transmission
coefficient are analytically obtained by using of the reactive flux method. The
long memory aspect of friction is revealed to originate a non-monotonic
$\delta$(power exponent of the friction) dependence of the passing probability,
the optimal incident angle of the particle and the steady anomalous
transmission coefficient. In the long time limit a bigger steady transmission
coefficient is obtained which means less barrier recrossing than the
one-dimensional case.",0905.2074v1
2009-06-04,Viscous cavity damping of a microlever in a simple fluid,"We consider the problem of oscillation damping in air of a thermally actuated
microlever as it is gradually approached towards an infinite wall in parallel
geometry. As the gap is decreased from 20 nm down to 400 nm, we observe the
increasing damping of the lever Brownian motion in the fluid laminar regime.
This manifests itself as a linear decrease with distance of the lever quality
factor accompanied by a dramatic softening of its resonance, and eventually
leads to the freezing of the CL oscillation. We are able to quantitatively
explain this behavior by analytically solving the Navier-Stokes equation with
perfect slip boundary conditions. Our findings may have implications for
microfluidics and micro- nano-electromechanical applications.",0906.0782v1
2009-06-19,Wakefield damping for the CLIC crab cavity,"A crab cavity is required in the CLIC to allow effective head-on collision of
bunches at the IP. A high operating frequency is preferred as the deflection
voltage required for a given rotation angle and the RF phase tolerance for a
crab cavity are inversely proportional to the operating frequency. The short
bunch spacing of the CLIC scheme and the high sensitivity of the crab cavity to
dipole kicks demand very high damping of the inter-bunch wakes, the major
contributor to the luminosity loss of colliding bunches. This paper
investigates the nature of the wakefields in the CLIC crab cavity and the
possibility of using various damping schemes to suppress them effectively.",0906.3593v1
2009-07-06,Non-Fermi liquid behavior due to U(1) gauge field in two dimensions,"We study the damping rate of massless Dirac fermions due to the U(1) gauge
field in (2+1)-dimensional quantum electrodynamics. In the absence of a Maxwell
term for the gauge field, the fermion damping rate
$\mathrm{Im}\Sigma(\omega,T)$ is found to diverge in both perturbative and
self-consistent results. In the presence of a Maxwell term, there is still
divergence in the perturbative results for $\mathrm{Im}\Sigma(\omega,T)$. Once
the Maxwell term is included into the self-consistent equations for fermion
self-energy and vacuum polarization functions, the fermion damping rate is free
of divergence and exhibits non-Fermi liquid behavior:
$\mathrm{Im}\Sigma(\omega,T) \propto \mathrm{max}(\sqrt{\omega},\sqrt{T})$.",0907.1022v3
2009-07-30,Gas damping force noise on a macroscopic test body in an infinite gas reservoir,"We present a simple analysis of the force noise associated with the
mechanical damping of the motion of a test body surrounded by a large volume of
rarefied gas. The calculation is performed considering the momentum imparted by
inelastic collisions against the sides of a cubic test mass, and for other
geometries for which the force noise could be an experimental limitation. In
addition to arriving at an accurated estimate, by two alternative methods, we
discuss the limits of the applicability of this analysis to realistic
experimental configurations in which a test body is surrounded by residual gas
inside an enclosure that is only slightly larger than the test body itself.",0907.5375v2
2009-08-19,Nonlinear viscoelastic wave propagation: an extension of Nearly Constant Attenuation (NCQ) models,"Hysteretic damping is often modeled by means of linear viscoelastic
approaches such as ""nearly constant Attenuation (NCQ)"" models. These models do
not take into account nonlinear effects either on the stiffness or on the
damping, which are well known features of soil dynamic behavior. The aim of
this paper is to propose a mechanical model involving nonlinear viscoelastic
behavior for isotropic materials. This model simultaneously takes into account
nonlinear elasticity and nonlinear damping. On the one hand, the shear modulus
is a function of the excitation level; on the other, the description of
viscosity is based on a generalized Maxwell body involving non-linearity. This
formulation is implemented into a 1D finite element approach for a dry soil.
The validation of the model shows its ability to retrieve low amplitude ground
motion response. For larger excitation levels, the analysis of seismic wave
propagation in a nonlinear soil layer over an elastic bedrock leads to results
which are physically satisfactory (lower amplitudes, larger time delays, higher
frequency content).",0908.2715v2
2009-09-30,Electronic damping of molecular motion at metal surfaces,"A method for the calculation of the damping rate due to electron-hole pair
excitation for atomic and molecular motion at metal surfaces is presented. The
theoretical basis is provided by Time Dependent Density Functional Theory
(TDDFT) in the quasi-static limit and calculations are performed within a
standard plane-wave, pseudopotential framework. The artificial periodicity
introduced by using a super-cell geometry is removed to derive results for the
motion of an isolated atom or molecule, rather than for the coherent motion of
an ordered over-layer. The algorithm is implemented in parallel, distributed
across both ${\bf k}$ and ${\bf g}$ space, and in a form compatible with the
CASTEP code. Test results for the damping of the motion of hydrogen atoms above
the Cu(111) surface are presented.",0909.5495v1
2009-10-14,Constraint on the growth factor of the cosmic structure from the damping of the baryon acoustic oscillation signature,"We determine a constraint on the growth factor by measuring the damping of
the baryon acoustic oscillations in the matter power spectrum using the Sloan
Digital Sky Survey luminous red galaxy sample. The damping of the BAO is
detected at the one sigma level. We obtain \sigma_8D_1(z=0.3) =
0.42^{+0.34}_{-0.28} at the 1\sigma statistical level, where \sigma_8 is the
root mean square overdensity in a sphere of radius 8h^{-1}Mpc and D_1(z) is the
growth factor at redshift z. The above result assumes that other parameters are
fixed and the cosmology is taken to be a spatially flat cold dark matter
universe with the cosmological constant.",0910.2513v1
2009-10-27,On the Interpretation of Magnetic Helicity Signatures in the Dissipation Range of Solar Wind Turbulence,"Measurements of small-scale turbulent fluctuations in the solar wind find a
non-zero right-handed magnetic helicity. This has been interpreted as evidence
for ion cyclotron damping. However, theoretical and empirical evidence suggests
that the majority of the energy in solar wind turbulence resides in low
frequency anisotropic kinetic Alfven wave fluctuations that are not subject to
ion cyclotron damping. We demonstrate that a dissipation range comprised of
kinetic Alfven waves also produces a net right-handed fluctuating magnetic
helicity signature consistent with observations. Thus, the observed magnetic
helicity signature does not necessarily imply that ion cyclotron damping is
energetically important in the solar wind.",0910.5023v1
2010-01-26,Damping in high-frequency metallic nanomechanical resonators,"We have studied damping in polycrystalline Al nanomechanical resonators by
measuring the temperature dependence of their resonance frequency and quality
factor over a temperature range of 0.1 - 4 K. Two regimes are clearly
distinguished with a crossover temperature of 1 K. Below 1 K we observe a
logarithmic temperature dependence of the frequency and linear dependence of
damping that cannot be explained by the existing standard models. We attribute
these phenomena to the effect of the two-level systems characterized by the
unexpectedly long (at least two orders of magnitude longer) relaxation times
and discuss possible microscopic models for such systems. We conclude that the
dynamics of the two-level systems is dominated by their interaction with
one-dimensional phonon modes of the resonators.",1001.4612v1
2010-04-28,Inviscid dynamical structures near Couette flow,"Consider inviscid fluids in a channel {-1<y<1}. For the Couette flow
v_0=(y,0), the vertical velocity of solutions to the linearized Euler equation
at v_0 decays in time. At the nonlinear level, such inviscid damping has not
been proved. First, we show that in any (vorticity) H^{s}(s<(3/2)) neighborhood
of Couette flow, there exist non-parallel steady flows with arbitrary minimal
horizontal period. This implies that nonlinear inviscid damping is not true in
any (vorticity) H^{s}(s<(3/2)) neighborhood of Couette flow and for any
horizontal period. Indeed, the long time behavior in such neighborhoods are
very rich, including nontrivial steady flows, stable and unstable manifolds of
nearby unstable shears. Second, in the (vorticity) H^{s}(s>(3/2)) neighborhood
of Couette, we show that there exist no non-parallel steadily travelling flows
v(x-ct,y), and no unstable shears. This suggests that the long time dynamics in
H^{s}(s>(3/2)) neighborhoods of Couette might be much simpler. Such contrasting
dynamics in H^{s} spaces with the critical power s=(3/2) is a truly nonlinear
phenomena, since the linear inviscid damping near Couette is true for any
initial vorticity in L^2.",1004.5149v1
2010-06-14,Parallel electric field amplification by phase-mixing of Alfven waves,"Previous numerical studies have identified ""phase mixing"" of low-frequency
Alfven waves as a mean of parallel electric field amplification and
acceleration of electrons in a collisionless plasma. Theoretical explanations
are given of how this produces an amplification of the parallel electric field,
and as a consequence, also leads to enhanced collisionless damping of the wave
by energy transfer to the electrons. Our results are based on the properties of
the Alfven waves in a warm plasma which are obtained from drift-kinetic theory,
in particular, the rate of their electron Landau damping. Phase mixing in a
collisionless low-$\beta$ plasma proceeds in a manner very similar to the
visco-resistive case, except for the fact that electron Landau damping is the
primary energy dissipation channel. The time and length scales involved are
evaluated. We also focus on the evolution of the parallel electric field and
calculate its maximum value in the course of its amplification.",1006.2729v1
2010-07-19,Anomalously large damping of long-wavelength quasiparticles caused by long-range interaction,"We demonstrate that long-range interaction in a system can lead to a very
strong interaction between long-wavelength quasiparticles and make them heavily
damped. In particular, we discuss magnon spectrum using 1/S expansion in 3D
Heisenberg ferromagnet (FM) with arbitrary small dipolar forces at T<<T_C. We
obtain that a fraction of long-wavelength magnons with energies e_k<T has
anomalously large damping G_k (ratio G_k/e_k reaches 0.3 for certain k). This
effect is observed both in quantum and classical FMs. Remarkably, this result
contradicts expectation of the quasiparticle concept according which a weakly
excited state of a many-body system can be represented as a collection of
weakly interacting elementary excitations. Particular materials are pointed out
which are suitable for corresponding experiments.",1007.3081v2
2010-07-29,The Quasinormal Mode Spectrum of a Kerr Black Hole in the Eikonal Limit,"It is well established that the response of a black hole to a generic
perturbation is characterized by a spectrum of damped resonances, called
quasinormal modes; and that, in the limit of large angular momentum ($l \gg
1$), the quasinormal mode frequency spectrum is related to the properties of
unstable null orbits. In this paper we develop an expansion method to explore
the link. We obtain new closed-form approximations for the lightly-damped part
of the spectrum in the large-$l$ regime. We confirm that, at leading order in
$l$, the resonance frequency is linked to the orbital frequency, and the
resonance damping to the Lyapunov exponent, of the relevant null orbit. We go
somewhat further than previous studies to establish (i) a spin-dependent
correction to the frequency at order $1 / l$ for equatorial ($m = \pm l$)
modes, and (ii) a new result for polar modes ($m = 0$). We validate the
approach by testing the closed-form approximations against frequencies obtained
numerically with Leaver's method.",1007.5097v1
2010-08-30,"Caldeira-Leggett Model, Landau Damping, and the Vlasov-Poisson System","The Caldeira-Leggett Hamiltonian (Eq. (1) below) describes the interaction of
a discrete harmonic oscillator with a continuous bath of harmonic oscillators.
This system is a standard model of dissipation in macroscopic low temperature
physics, and has applications to superconductors, quantum computing, and
macroscopic quantum tunneling. The similarities between the Caldeira-Leggett
model and the linearized Vlasov-Poisson equation are analyzed, and it is shown
that the damping in the Caldeira-Leggett model is analogous to that of Landau
damping in plasmas [1]. An invertible linear transformation [2, 3] is presented
that converts solutions of the Caldeira-Leggett model into solutions of the
linearized Vlasov-Poisson system.",1008.5190v1
2010-09-09,A number-conserving linear response study of low-velocity ion stopping in a collisional magnetized classical plasma,"The results of a theoretical investigation on the low-velocity stopping power
of the ions moving in a magnetized collisional plasma are presented. The
stopping power for an ion is calculated employing linear response theory using
the dielectric function approach. The collisions, which leads to a damping of
the excitations in the plasma, is taken into account through a
number-conserving relaxation time approximation in the linear response
function. In order to highlight the effects of collisions and magnetic field we
present a comparison of our analytical and numerical results obtained for a
nonzero damping or magnetic field with those for a vanishing damping or
magnetic field. It is shown that the collisions remove the anomalous friction
obtained previously [Nersisyan et al., Phys. Rev. E 61, 7022 (2000)] for the
collisionless magnetized plasmas at low ion velocities. One of major objectives
of this study is to compare and contrast our theoretical results with those
obtained through a novel diffusion formulation based on Dufty-Berkovsky
relation evaluated in magnetized one-component plasma models framed on target
ions and electrons.",1009.1700v1
2010-10-03,A High Phase Advance Damped and Detuned Structure for the Main Linacs of Clic,"The main accelerating structures for the CLIC are designed to operate at an
average accelerating gradient of 100 MV/m. The accelerating frequency has been
optimised to 11.994 GHz with a phase advance of 2{\pi}/3 of the main
accelerating mode. The moderately damped and detuned structure (DDS) design is
being studied as an alternative to the strongly damped WDS design. Both these
designs are based on the nominal accelerating phase advance. Here we explore
high phase advance (HPA) structures in which the group velocity of the rf
fields is reduced compared to that of standard (2{\pi}/3) structures. The
electrical breakdown strongly depends on the fundamental mode group velocity.
Hence it is expected that electrical breakdown is less likely to occur in the
HPA structures. We report on a study of both the fundamental and dipole modes
in a CLIC_DDS_HPA structure, designed to operate at 5{\pi}/6 phase advance per
cell. Higher order dipole modes in both the standard and HPA structures are
also studied.",1010.0438v1
2010-10-23,Environmental influences on Quantum Monty Hall problem,"We reformulate the quantum Monty Hall problem in the presence of decoherence.
The decoherence destroys the fairness of the game. A new Nash equilibrium for a
particular strategy profile in the presence of decoherence emerges. It is shown
that in the presence of decoherence under the action of amplitude damping
channel, Bob's winning probability is always higher than three-forth,
irrespective of Alice's strategy, if he does not switch to the other door and
always wins for a fully decohered case of the channel. Depolarizing channel
damps up Bob's winning probability and gets better off if he sticks to his
current selection. Phase damping channel leaves the winning probability
unaffected. Unlike the classical and the quantum forms of the game, Bob's
dominant strategy in the presence of decoherence is not switching.",1010.4875v2
2010-12-14,Controlling transfer of quantum correlations among bi-partitions of a composite quantum system by combining noisy environments,"The correlation dynamics is investigated for various bi-partitions of a
composite system consisting of two qubits, and two independent and
non-identical noisy environments. The two qubits have no direct interaction
with each other and locally interact with their environments. Classical and
quantum correlations including entanglement are initially prepared only between
the two qubits. We find that, contrary to the identical noisy environment case,
the entanglement and quantum correlation transfer directions can be controlled
by combining different noisy environments. The amplitude damping environment
determines whether there exists entanglement transfer among the bi-partitions
of a composite system. When one qubit is coupled to an amplitude damping
environment but another one to a bit-flip one, we find a very interesting
result that all the quantum and classical correlations, and even the
entanglement, originally existing between the qubits, can be completely
transferred without any loss to the qubit coupled to the bit-flip environment
and the amplitude-damping environment. We also notice that it is possible to
distinguish the quantum correlation from the classical correlation and
entanglement by combining different noisy environments.",1012.3033v1
2010-12-22,Viscous damping of r-modes: Small amplitude instability,"We study the viscous damping of r-modes of compact stars and analyze in
detail the regions where small amplitude modes are unstable to the emission of
gravitational radiation. We present general expressions for the viscous damping
times for arbitrary forms of interacting dense matter and derive general
semi-analytic results for the boundary of the instability region. These results
show that many aspects, like in particular the physically important minima of
the instability boundary, are surprisingly insensitive to detailed microscopic
properties of the considered form of matter. Our general expressions are
applied to the cases of hadronic stars, strange stars, and hybrid stars, and we
focus on equations of state that are compatible with the recent measurement of
a heavy compact star. We find that hybrid stars with a sufficiently small core
can ""masquerade"" as neutron stars and feature an instability region that is
indistinguishable from that of a neutron star, whereas neutron stars with a
core density high enough to allow direct Urca reactions feature a notch on the
right side of the instability region.",1012.4883v2
2010-12-25,Screw-pitch effect and velocity oscillation of domain-wall in ferromagnetic nanowire driven by spin-polarized current,"We investigate the dynamics of domain wall in ferromagnetic nanowire with
spin-transfer torque. The critical current condition is obtained analytically.
Below the critical current, we get the static domain wall solution which shows
that the spin-polarized current can't drive domain wall moving continuously. In
this case, the spin-transfer torque plays both the anti-precession and
anti-damping roles, which counteracts not only the spin-precession driven by
the effective field but also Gilbert damping to the moment. Above the critical
value, the dynamics of domain wall exhibits the novel screw-pitch effect
characterized by the temporal oscillation of domain wall velocity and width,
respectively. Both the theoretical analysis and numerical simulation
demonstrate that this novel phenomenon arise from the conjunctive action of
Gilbert-damping and spin-transfer torque. We also find that the roles of
spin-transfer torque are entirely contrary for the cases of below and above the
critical current.",1012.5473v1
2010-12-27,Phenomenology of Current-Induced Dynamics in Antiferromagnets,"We derive a phenomenological theory of current-induced staggered
magnetization dynamics in antiferromagnets. The theory captures the reactive
and dissipative current-induced torques and the conventional effects of
magnetic fields and damping. A Walker ansatz describes the dc current-induced
domain-wall motion when there is no dissipation. If magnetic damping and
dissipative torques are included, the Walker ansatz remains robust when the
domain-wall moves slowly. As in ferromagnets, the domain-wall velocity is
proportional to the ratio between the dissipative-torque and the magnetization
damping. In addition, a current-driven antiferromagnetic domain-wall acquires a
net magnetic moment.",1012.5655v2
2011-02-02,"Harmonic Oscillator in Heat Bath: Exact simulation of time-lapse-recorded data, exact analytical benchmark statistics","The stochastic dynamics of the damped harmonic oscillator in a heat bath is
simulated with an algorithm that is exact for time steps of arbitrary size.
Exact analytical results are given for correlation functions and power spectra
in the form they acquire when computed from experimental time-lapse recordings.
Three applications are discussed: (i) Effects of finite sampling-rate and
-time, described exactly here, are similar for other stochastic dynamical
systems-e.g. motile micro-organisms and their time-lapse recorded trajectories.
(ii) The same statistics is satisfied by any experimental system to the extent
it is interpreted as a damped harmonic oscillator at finite temperature-such as
an AFM cantilever. (iii) Three other models of fundamental interest are
limiting cases of the damped harmonic oscillator at finite temperature; it
consequently bridges their differences and describes effects of finite sampling
rate and sampling time for these models as well. Finally, we give a brief
discussion of nondimensionalization.",1102.0524v1
2011-02-04,A symmetry trip from Caldirola to Bateman damped systems,"For the Caldirola-Kanai system, describing a quantum damped harmonic
oscillator, a couple of constant-of-motion operators generating the Heisenberg
algebra can be found. The inclusion of the standard time evolution symmetry in
this algebra for damped systems, in a unitary manner, requires a non-trivial
extension of this basic algebra and hence the physical system itself.
Surprisingly, this extension leads directly to the so-called Bateman's dual
system, which now includes a new particle acting as an energy reservoir. The
group of symmetries of the dual system is presented, as well as a quantization
that implies, in particular, a first-order Schr\""odinger equation. The usual
second-order equation and the inclusion of the original Caldirola-Kanai model
in Bateman's system are also discussed.",1102.0990v1
2011-03-03,Determination of the pairing state in iron-based superconductors through neutron scattering,"We calculate the spin susceptibility in the s_{+-} and s_{++} superconducting
states of the iron pnictides using the effective five orbital model and
considering the quasiparticle damping. For the experimentally evaluated
magnitude of the quasiparticle damping and the superconducting gap, the results
at the wave vector ~ (pi,0) show that the s_{+-} state is more consistent with
the neutron scattering experiments, while for larger quasiparticle damping and
the superconducting gap, the s_{++} state can be more consistent. To
distinguish between two cases that reproduce the experiments at the wave vector
~ (pi,0), we propose to investigate experimentally the wave vector ~ (pi,pi).",1103.0586v2
2011-03-03,Transmission of classical and quantum information through a quantum memory channel with damping,"We consider the transfer of classical and quantum information through a
memory amplitude damping channel. Such a quantum channel is modeled as a damped
harmonic oscillator, the interaction between the information carriers - a train
of qubits - and the oscillator being of the Jaynes-Cummings kind. We prove that
this memory channel is forgetful, so that quantum coding theorems hold for its
capacities. We analyze entropic quantities relative to two uses of this
channel. We show that memory effects improve the channel aptitude to transmit
both classical and quantum information, and we investigate the mechanism by
which memory acts in changing the channel transmission properties.",1103.0747v2
2011-03-08,Steady states of the parametric rotator and pendulum,"We discuss several steady-state rotation and oscillation modes of the planar
parametric rotator and pendulum with damping. We consider a general elliptic
trajectory of the suspension point for both rotator and pendulum, for the
latter at an arbitrary angle with gravity, with linear and circular
trajectories as particular cases. We treat the damped, non-linear equation of
motion of the parametric rotator and pendulum perturbatively for small
parametric excitation and damping, although our perturbative approach can be
extended to other regimes as well. Our treatment involves only ordinary
second-order differential equations with constant coefficients, and provides
numerically accurate perturbative solutions in terms of elementary functions.
Some of the steady-state rotation and oscillation modes studied here have not
been discussed in the previous literature. Other well-known ones, such as
parametric resonance and the inverted pendulum, are extended to elliptic
parametric excitation tilted with respect to gravity. The results presented
here should be accessible to advanced undergraduates, and of interest to
graduate students and specialists in the field of non-linear mechanics.",1103.1413v1
2011-03-18,Time-periodic solitons in a damped-driven nonlinear Schrödinger equation,"Time-periodic solitons of the parametrically driven damped nonlinear
Schr\""odinger equation are obtained as solutions of the boundary-value problem
on a two-dimensional spatiotemporal domain. We follow the transformation of the
periodic solitons as the strength of the driver is varied. The resulting
bifurcation diagrams provide a natural explanation for the overall form and
details of the attractor chart compiled previously via direct numerical
simulations. In particular, the diagrams confirm the occurrence of the
period-doubling transition to temporal chaos for small values of dissipation
and the absence of such transitions for larger dampings. This difference in the
soliton's response to the increasing driving strength can be traced to the
difference in the radiation frequencies in the two cases. Finally, we relate
the soliton's temporal chaos to the homoclinic bifurcation.",1103.3604v1
2011-03-28,Motion of position-dependent mass as a damping-antidamping process: Application to the Fermi gas and to the Morse potential,"The object of this paper is to investigate, classically and quantum
mechanically, the relation existing between the position-dependent effective
mass and damping-antidamping dynamics. The quantization of the equations of
motion is carried out using the geometric interpretation of the motion, and we
compare it with the one based on the ordering ambiguity scheme. Furthermore, we
apply the obtained results to a Fermi gas of damped-antidamped particles, and
we solve the Schr\""odinger equation for an exponentially increasing
(decreasing) mass in the presence of the Morse potential.",1103.5440v3
2011-04-08,Magnetization Dissipation in Ferromagnets from Scattering Theory,"The magnetization dynamics of ferromagnets are often formulated in terms of
the Landau-Lifshitz-Gilbert (LLG) equation. The reactive part of this equation
describes the response of the magnetization in terms of effective fields,
whereas the dissipative part is parameterized by the Gilbert damping tensor. We
formulate a scattering theory for the magnetization dynamics and map this
description on the linearized LLG equation by attaching electric contacts to
the ferromagnet. The reactive part can then be expressed in terms of the static
scattering matrix. The dissipative contribution to the low-frequency
magnetization dynamics can be described as an adiabatic energy pumping process
to the electronic subsystem by the time-dependent magnetization. The Gilbert
damping tensor depends on the time derivative of the scattering matrix as a
function of the magnetization direction. By the fluctuation-dissipation
theorem, the fluctuations of the effective fields can also be formulated in
terms of the quasistatic scattering matrix. The theory is formulated for
general magnetization textures and worked out for monodomain precessions and
domain wall motions. We prove that the Gilbert damping from scattering theory
is identical to the result obtained by the Kubo formalism.",1104.1625v1
2011-04-30,Resonantly Damped Propagating Kink Waves in Longitudinally Stratified Solar Waveguides,"It has been shown that resonant absorption is a robust physical mechanism to
explain the observed damping of magnetohydrodynamic (MHD) kink waves in the
solar atmosphere due to naturally occurring plasma inhomogeneity in the
direction transverse to the direction of the magnetic field. Theoretical
studies of this damping mechanism were greatly inspired by the first
observations of post-flare standing kink modes in coronal loops using the
Transition Region And Coronal Explorer (TRACE). More recently, these studies
have been extended to explain the attenuation of propagating coronal kink waves
observed by the Coronal Multi-Channel Polarimeter (CoMP). In the present study,
for the first time we investigate the properties of propagating kink waves in
solar waveguides including the effects of both longitudinal and transverse
plasma inhomogeneity. Importantly, it is found that the wavelength is only
dependent on the longitudinal stratification and the amplitude is simply a
product of the two effects. In light of these results the advancement of solar
atmospheric magnetoseismology by exploiting high spatial/temporal resolution
observations of propagating kink waves in magnetic waveguides to determine the
length scales of the plasma inhomogeneity along and transverse to the direction
of the magnetic field is discussed.",1105.0067v1
2011-05-05,The effect of twisted magnetic field on the resonant absorption of MHD waves in coronal loops,"The standing quasi modes in a cylindrical incompressible flux tube with
magnetic twist that undergoes a radial density structuring is considered in
ideal magnetohydrodynamics (MHD). The radial structuring is assumed to be a
linearly varying density profile. Using the relevant connection formulae, the
dispersion relation for the MHD waves is derived and solved numerically to
obtain both the frequencies and damping rates of the fundamental and
first-overtone modes of both the kink (m=1) and fluting (m=2,3) waves. It was
found that a magnetic twist will increase the frequencies, damping rates and
the ratio of the oscillation frequency to the damping rate of these modes. The
period ratio P_1/P_2 of the fundamental and its first-overtone surface waves
for kink (m=1) and fluting (m=2,3) modes is lower than 2 (the value for an
untwisted loop) in the presence of twisted magnetic field. For the kink modes,
particularly, the magnetic twists B_{\phi}/B_z=0.0065 and 0.0255 can achieve
deviations from 2 of the same order of magnitude as in the observations.
Furthermore, for the fundamental kink body waves, the frequency bandwidth
increases with increasing the magnetic twist.",1105.1120v1
2011-05-05,Interpreting Graph Cuts as a Max-Product Algorithm,"The maximum a posteriori (MAP) configuration of binary variable models with
submodular graph-structured energy functions can be found efficiently and
exactly by graph cuts. Max-product belief propagation (MP) has been shown to be
suboptimal on this class of energy functions by a canonical counterexample
where MP converges to a suboptimal fixed point (Kulesza & Pereira, 2008).
  In this work, we show that under a particular scheduling and damping scheme,
MP is equivalent to graph cuts, and thus optimal. We explain the apparent
contradiction by showing that with proper scheduling and damping, MP always
converges to an optimal fixed point. Thus, the canonical counterexample only
shows the suboptimality of MP with a particular suboptimal choice of schedule
and damping. With proper choices, MP is optimal.",1105.1178v1
2011-05-14,Crossovers in the non-Markovian dynamics of two-qubit entanglements,"We study the entanglement dynamics of two non-interacting, spatially
separated qubits subject to local environment noises. Based on exactly solvable
models for non-Markovian amplitude damping and phase damping noises, we are
able to analyze the entanglement dynamics of the two qubits for different
coupling bandwidths and different detunings. We show that entanglement
oscillations can occur for both amplitude and phase damping noises. Moreover,
we demonstrate that changing the coupling bandwidth can lead to crossover
between dissipative and non-dissipative entanglement dynamics, while varying
the detuning controls the crossover between strong and weak coupling limits.
Our findings can help provide a synthesized picture for the entanglement
dynamics of two qubits subject to local environment noises.",1105.2859v2
2011-06-17,Controlling Excitations Inversion of a Cooper Pair Box Interacting with a Nanomechanical Resonator,"We investigate the action of time dependent detunings upon the excitation
inversion of a Cooper pair box interacting with a nanomechanical resonator. The
method employs the Jaynes-Cummings model with damping, assuming different decay
rates of the Cooper pair box and various fixed and t-dependent detunings. It is
shown that while the presence of damping plus constant detunings destroy the
collapse/revival effects, convenient choices of time dependent detunings allow
one to reconstruct such events in a perfect way. It is also shown that the mean
excitation of the nanomechanical resonator is more robust against damping of
the Cooper pair box for convenient values of t-dependent detunings.",1106.3379v1
2011-06-22,Tunable Magnonic Frequency and Damping in [Co/Pd]8 Multilayers with Variable Co Layer Thickness,"We report the experimental observation of collective picosecond magnetization
dynamics in [Co/Pd]8 multilayers with perpendicular magnetic anisotropy. The
precession frequency shows large and systematic variation from about 5 GHz to
about 90 GHz with the decrease in the Co layer thickness from 1.0 nm to 0.22 nm
due to the linear increase in the perpendicular magnetic anisotropy. The
damping coefficient 'alpha' is found to be inversely proportional to the Co
layer thickness and a linear relation between the perpendicular magnetic
anisotropy and 'alpha' is established. We discuss the possible reasons behind
the enhanced damping as the d-d hybridization at the interface and spin
pumping. These observations are significant for the applications of these
materials in spintronics and magnonic crystals.",1106.4491v1
2011-07-04,An HI column density threshold for cold gas formation in the Galaxy,"We report the discovery of a threshold in the HI column density of Galactic
gas clouds below which the formation of the cold phase of HI is inhibited. This
threshold is at $N_{HI} = 2 \times 10^{20}$ per cm$^{2}$; sightlines with lower
HI column densities have high spin temperatures (median $T_s \sim 1800$ K),
indicating low fractions of the cold neutral medium (CNM), while sightlines
with $N_{HI} \ge 2 \times 10^{20}$ per cm$^{2}$ have low spin temperatures
(median $T_s \sim 240$ K), implying high CNM fractions. The threshold for CNM
formation is likely to arise due to inefficient self-shielding against
ultraviolet photons at lower HI column densities. The threshold is similar to
the defining column density of a damped Lyman-$\alpha$ absorber; this indicates
a physical difference between damped and sub-damped Lyman-$\alpha$ systems,
with the latter class of absorbers containing predominantly warm gas.",1107.0744v2
2011-07-11,One-dimensional vertical dust strings in a glass box,"The oscillation spectrum of a one-dimensional vertical dust string formed
inside a glass box on top of the lower electrode in a GEC reference cell was
studied. A mechanism for creating a single vertical dust string is described.
It is shown that the oscillation amplitudes, resonance frequencies, damping
coefficients, and oscillation phases of the dust particles separate into two
distinct groups. One group exhibits low damping coefficients, increasing
amplitudes and decreasing resonance frequencies for dust particles closer to
the lower electrode. The other group shows high damping coefficients but
anomalous resonance frequencies and amplitudes. At low oscillation frequencies,
the two groups are also separated by a {\pi}-phase difference. One possible
cause for the difference in behavior between the two groups is discussed.",1107.2074v1
2011-07-24,Traveling kinks in cubic nonlinear Ginzburg-Landau equations,"Nonlinear cubic Euler-Lagrange equations of motion in the traveling variable
are usually derived from Ginzburg-Landau free energy functionals frequently
encountered in several fields of physics. Many authors considered in the past
damped versions of such equations with the damping term added by hand
simulating the friction due to the environment. It is known that even in this
damped case kink solutions can exist. By means of a factorization method, we
provide analytic formulas for several possible kink solutions of such equations
of motion in the undriven and constant field driven cases, including the
recently introduced Riccati parameter kinks which were not considered
previously in such a context. The latter parameter controls the delay of the
switching stage of the kinks",1107.4773v4
2011-08-22,On conditions for asymptotic stability of dissipative infinite-dimensional systems with intermittent damping,"We study the asymptotic stability of a dissipative evolution in a Hilbert
space subject to intermittent damping. We observe that, even if the
intermittence satisfies a persistent excitation condition, if the Hilbert space
is infinite-dimensional then the system needs not being asymptotically stable
(not even in the weak sense). Exponential stability is recovered under a
generalized observability inequality, allowing for time-domains that are not
intervals. Weak asymptotic stability is obtained under a similarly generalized
unique continuation principle. Finally, strong asymptotic stability is proved
for intermittences that do not necessarily satisfy some persistent excitation
condition, evaluating their total contribution to the decay of the trajectories
of the damped system. Our results are discussed using the example of the wave
equation, Schr\""odinger's equation and, for strong stability, also the special
case of finite-dimensional systems.",1108.4327v2
2011-08-26,Aligned Major Axes in a Planetary System without Tidal Evolution: The 61 Virginis example,"Tidal damping of one of the orbits in a planetary system can lead to aligned
major-axes (the so-called ""fixed-point"" condition), but currently aligned major
axes do not necessarily imply such a history. An example is the nominal orbital
solution for the 61 Virginis system where two orbits librate about alignment,
but evaluation of the eigenmodes of the secular theory shows it could not be
the result of tidal damping but rather of initial conditions. Nevertheless, the
amplitudes of the eigenmodes suggest that this system may have undergone some
degree of tidal damping.",1108.5369v1
2011-09-09,Optimal linear optical implementation of a single-qubit damping channel,"We experimentally demonstrate a single-qubit decohering quantum channel using
linear optics. We implement the channel, whose special cases include both the
amplitude-damping channel and the bit-flip channel, using a single, static
optical setup. Following a recent theoretical result [M. Piani et al., Phys.
Rev. A, 84, 032304 (2011)], we realize the channel in an optimal way,
maximizing the probability of success, i.e., the probability for the photonic
qubit to remain in its encoding. Using a two-photon entangled resource, we
characterize the channel using ancilla-assisted process tomography and find
average process fidelities of 0.9808 \pm 0.0002 and 0.9762 \pm 0.0002 for
amplitude-damping and the bit-flip case, respectively.",1109.2070v1
2011-12-02,An energy-based computational method in the analysis of the transmission of energy in a chain of coupled oscillators,"In this paper we study the phenomenon of nonlinear supratransmission in a
semi-infinite discrete chain of coupled oscillators described by modified
sine-Gordon equations with constant external and internal damping, and subject
to harmonic external driving at the end. We develop a consistent and
conditionally stable finite-difference scheme in order to analyze the effect of
damping in the amount of energy injected in the chain of oscillators; numerical
bifurcation analyses to determine the dependence of the amplitude at which
supratransmission first occurs with respect to the frequency of the driving
oscillator are carried out in order to show the consequences of damping on
harmonic phonon quenching and the delay of appearance of critical amplitude.",1112.0581v1
2012-06-11,Testing the 130 GeV gamma-ray line with high energy resolution detectors,"Recently some hints of the existence of $\gamma$-ray line around 130 GeV are
reported according to the analysis of Fermi-LAT data. If confirmed it would be
the first direct evidence to show the existence of new physics beyond the
standard model. Here we suggest that using the forthcoming high energy
resolution $\gamma$-ray detectors, such as CALET and DAMPE, we may test whether
it is real line structure or just the background effect. For DAMPE like
detector with designed energy resolution $\sim1.5%$, a line significance will
reach $11\sigma$ for the same statistics as Fermi-LAT. For about 1.4 yr survey
observation, DAMPE may detect a $5\sigma$ signal of such a $\gamma$-ray line.",1206.2241v2
2012-06-14,Finite-temperature dynamics of matter-wave dark solitons in linear and periodic potentials: an example of an anti-damped Josephson junction,"We study matter-wave dark solitons in atomic Bose-Einstein condensates at
finite temperatures, under the effect of linear and periodic potentials. Our
model, namely a dissipative Gross-Pitaevskii equation, is treated analytically
by means of dark soliton perturbation theory, which results in a Newtonian
equation of motion for the dark soliton center. This reduced model, which
incorporates an effective washboard potential and an anti-damping term,
constitutes an example of an anti-damped Josephson junction. We present a
qualitative (local and global) analysis of the equation of motion. For
sufficiently small wavenumbers of the periodic potential and weak linear
potentials, the results are found to be in good agreement with pertinent ones
obtained via a Bogoliubov-de Gennes analysis and direct numerical simulations.",1206.2993v1
2012-06-15,Damping of giant dipole resonance in hot rotating nuclei,"The phonon damping model (PDM) is extended to include the effect of angular
momentum at finite temperature. The model is applied to the study of damping of
giant dipole resonance (GDR) in hot and noncollectively rotating spherical
nuclei. The numerical results obtained for Mo88 and Sn106 show that the GDR
width increases with both temperature T and angular momentum M. At T > 4 MeV
and M<= 60 hbar the increase in the GDR width slows down for Sn106, whereas at
M<= 80 hbar the GDR widths in both nuclei nearly saturate. By adopting the
nuclear shear viscosity extracted from fission data at T= 0, it is shown that
the maximal value of the angular momentum for Mo88 and Sn106 should be around
46 and 55 hbar, respectively, so that the universal conjecture for the lower
bound of the specific shear viscosity for all fluids is not violated up to T= 5
MeV.",1206.3361v1
2012-06-18,Sampled-data design for robust control of a single qubit,"This paper presents a sampled-data approach for the robust control of a
single qubit (quantum bit). The required robustness is defined using a sliding
mode domain and the control law is designed offline and then utilized online
with a single qubit having bounded uncertainties. Two classes of uncertainties
are considered involving the system Hamiltonian and the coupling strength of
the system-environment interaction. Four cases are analyzed in detail including
without decoherence, with amplitude damping decoherence, phase damping
decoherence and depolarizing decoherence. Sampling periods are specifically
designed for these cases to guarantee the required robustness. Two sufficient
conditions are presented for guiding the design of unitary control for the
cases without decoherence and with amplitude damping decoherence. The proposed
approach has potential applications in quantum error-correction and in
constructing robust quantum gates.",1206.3897v2
2012-06-25,Trap anharmonicity and sloshing mode of a Fermi gas,"For a gas trapped in a harmonic potential, the sloshing (or Kohn) mode is
undamped and its frequency coincides with the trap frequency, independently of
the statistics, interaction and temperature of the gas. However, experimental
trap potentials have usually Gaussian shape and anharmonicity effects appear as
the temperature and, in the case of Fermions, the filling of the trap are
increased. We study the sloshing mode of a degenerate Fermi gas in an
anharmonic trap within the Boltzmann equation, including in-medium effects in
both the transport and collision terms. The calculated frequency shifts and
damping rates of the sloshing mode due to the trap anharmonicity are in
satisfactory agreement with the available experimental data. We also discuss
higher-order dipole, octupole, and bending modes and show that the damping of
the sloshing mode is caused by its coupling to these modes.",1206.5688v2
2012-09-06,Radiative energy loss in the absorptive QGP: taming the long formation lengths in coherent emission,"In an absorptive plasma, damping of radiation mechanisms can influence the
bremsstrahlung formation in case of large radiation formation lengths. We study
qualitatively the influence of this effect on the gluon bremsstrahlung spectrum
off heavy quarks in the quark-gluon plasma. Independent of the heavy-quark
mass, the spectrum is found to be strongly suppressed in an intermediate gluon
energy region which grows with increasing gluon damping rate and increasing
energy of the heavy quark. Thus, just as polarization effects in the plasma
render the bremsstrahlung spectra independent of the quark mass in the soft
gluon regime, damping effects tend to have a similar impact for larger gluon
energies.",1209.1149v1
2012-09-17,Power spectra in the eikonal approximation with adiabatic and non-adiabatic modes,"We use the so-called eikonal approximation, recently introduced in the
context of cosmological perturbation theory, to compute power spectra for
multi-component fluids. We demonstrate that, at any given order in standard
perturbation theory, multipoint power spectra do not depend on the large-scale
adiabatic modes. Moreover, we employ perturbation theories to decipher how
nonadiabatic modes, such as a relative velocity between two different
components, damp the small-scale matter power spectrum, a mechanism recently
described in the literature. In particular, we do an explicit calculation at
1-loop order of this effect. While the 1-loop result eventually breaks down, we
show how the damping effect can be fully captured by the help of the eikonal
approximation. A relative velocity not only induces mode damping but also
creates large-scale anisotropic modulations of the matter power spectrum
amplitude. We illustrate this for the Local Group environment.",1209.3662v2
2012-09-26,Linear response theory for hydrodynamic and kinetic equations with long-range interactions,"We apply the linear response theory to systems with long-range interactions
described by hydrodynamic equations such as the Euler, Smoluchowski, and damped
Euler equations. We analytically determine the response of the system submitted
to a pulse and to a step function. We compare these results with those obtained
for collisionless systems described by the Vlasov equation. We show that, in
the linear regime, the evolution of a collisionless system (Vlasov) with the
waterbag distribution is the same as the evolution of a collision-dominated gas
without dissipation (Euler). In this analogy, the maximum velocity of the
waterbag distribution plays the role of the velocity of sound in the
corresponding barotropic gas. When submitted to a step function, these systems
exhibit permanent oscillations. Other distributions exhibit Landau damping and
relax towards a steady state. We illustrate this behaviour with the Cauchy
distribution which can be studied analytically. We apply our results to the HMF
model and obtain a generalized Curie-Weiss law for the magnetic susceptibility.
Finally, we compare the linear response theory to the initial value problem for
the linearized Vlasov equation and report a case of algebraic damping of the
initial perturbation.",1209.5987v1
2012-09-15,Phase mixing of propagating Alfven waves in a stratified atmosphere: Solar spicules,"Alfvenic waves are thought to play an important role in coronal heating and
solar wind acceleration. Recent observations by Hinode/SOT showed that the
spicules mostly exhibit upward propagating high frequency waves. Here we
investigate the dissipation of such waves due to phase mixing in stratified
environment of solar spicules. Since they are highly dynamic structures with
speeds at about significant fractions of the Alfven phase speed, we take into
account the effects of steady flows. Our numerical simulations show that in the
presence of stratification due to gravity, damping takes place in space than in
time. The exponential damping low, exp(-At^3), is valid under spicule
conditions, however the calculated damping time is much longer than the
reported spicule lifetimes from observations.",1210.0485v1
2012-10-03,Effect of temperature and velocity on superlubricity,"We study the effects of temperature and sliding velocity on superlubricity in
numerical simulations of the Frenkel-Kontorova model. We show that resonant
excitations of the phonons in an incommensurate sliding body lead to an
effective friction and to thermal equilibrium with energy distributed over the
internal degrees of freedom. For finite temperature, the effective friction can
be described well by a viscous damping force, with a damping coefficient that
emerges naturally from the microscopic dynamics. This damping coefficient is a
non-monotonic function of the sliding velocity which peaks around resonant
velocities and increases with temperature. At low velocities, it remains finite
and nonzero, indicating the preservation of superlubricity in the zero-velocity
limit. Finally, we propose experimental systems in which our results could be
verified.",1210.1124v1
2012-10-04,Basic microscopic plasma physics unified and simplified by N-body classical mechanics,"Debye shielding, collisional transport, Landau damping of Langmuir waves, and
spontaneous emission of these waves are introduced, in typical plasma physics
textbooks, in different chapters. This paper provides a compact unified
introduction to these phenomena without appealing to fluid or kinetic models,
but by using Newton's second law for a system of $N$ electrons in a periodic
box with a neutralizing ionic background. A rigorous equation is derived for
the electrostatic potential. Its linearization and a first smoothing reveal
this potential to be the sum of the shielded Coulomb potentials of the
individual particles. Smoothing this sum yields the classical Vlasovian
expression including initial conditions in Landau contour calculations of
Langmuir wave growth or damping. The theory is extended to accommodate a
correct description of trapping or chaos due to Langmuir waves. In the linear
regime, the amplitude of such a wave is found to be ruled by Landau growth or
damping and by spontaneous emission. Using the shielded potential, the
collisional diffusion coefficient is computed for the first time by a
convergent expression including the correct calculation of deflections for all
impact parameters. Shielding and collisional transport are found to be two
related aspects of the repulsive deflections of electrons.",1210.1546v2
2012-10-11,Measurement of the damping of nuclear shell effect in the doubly magic $^{208}$Pb region,"The damping of the nuclear shell effect with excitation energy has been
measured through an analysis of the neutron spectra following the triton
transfer in the $^7$Li induced reaction on $^{205}$Tl. The measured neutron
spectra demonstrate the expected large shell correction energy for the nuclei
in the vicinity of doubly magic $^{208}$Pb and a small value for $^{184}$W. A
quantitative extraction of the allowed values of the damping parameter
$\gamma$, along with those for the asymptotic nuclear level density parameter
$\tilde{a}$, has been made for the first time.",1210.3213v2
2012-10-16,Optimal control of laser plasma instabilities using Spike Trains of Uneven Duration and Delay (STUD pulses) for ICF and IFE,"An adaptive method of controlling parametric instabilities in laser produced
plasmas is proposed. It involves fast temporal modulation of a laser pulse on
the fastest instability's amplification time scale, adapting to changing and
unknown plasma conditions. These pulses are comprised of on and off sequences
having at least one or two orders of magnitude contrast between them. Such
laser illumination profiles are called STUD pulses for Spike Trains of Uneven
Duration and Delay. The STUD pulse program includes scrambling the speckle
patterns spatially in between the laser spikes. The off times allow damping of
driven waves. The scrambling of the hot spots allows tens of damping times to
elapse before hot spot locations experience recurring high intensity spikes.
Damping in the meantime will have healed the scars of past growth. Another
unique feature of STUD pulses on crossing beams is that their temporal profiles
can be interlaced or staggered, and their interactions thus controlled with an
on-off switch and a dimmer.",1210.4462v1
2012-10-28,Mass Dependence of Instabilities of an Oscillator with Multiplicative and Additive Noise,"We study the instabilities of a harmonic oscillator subject to additive and
dichotomous multiplicative noise, focussing on the dependance of the
instability threshold on the mass. For multiplicative noise in the damping, the
instability threshold is crossed as the mass is decreased, as long as the
smaller damping is in fact negative. For multiplicative noise in the stiffness,
the situation is more complicated and in fact the transition is reentrant for
intermediate noise strength and damping. For multiplicative noise in the mass,
the results depend on the implementation of the noise. One can take the
velocity or the momentum to be conserved as the mass is changed. In these cases
increasing the mass destabilizes the system. Alternatively, if the change in
mass is caused by the accretion/loss of particles to the Brownian particle,
these processes are asymmetric with momentum conserved upon accretion and
velocity upon loss. In this case, there is no instability, as opposed to the
other two implementations. We also study the distribution of the energy,
finding a power-law cutoff at a value which increases with time.",1210.7433v1
2012-10-30,Extending the Concept of Analog Butterworth Filter for Fractional Order Systems,"This paper proposes the design of Fractional Order (FO) Butterworth filter in
complex w-plane (w=sq; q being any real number) considering the presence of
under-damped, hyper-damped, ultra-damped poles. This is the first attempt to
design such fractional Butterworth filters in complex w-plane instead of
complex s-plane, as conventionally done for integer order filters. Firstly, the
concept of fractional derivatives and w-plane stability of linear fractional
order systems are discussed. Detailed mathematical formulation for the design
of fractional Butterworth-like filter (FBWF) in w-plane is then presented.
Simulation examples are given along with a practical example to design the FO
Butterworth filter with given specifications in frequency domain to show the
practicability of the proposed formulation.",1210.8194v3
2012-11-15,Spin transport and tunable Gilbert damping in a single-molecule magnet junction,"We study time-dependent electronic and spin transport through an electronic
level connected to two leads and coupled with a single-molecule magnet via
exchange interaction. The molecular spin is treated as a classical variable and
precesses around an external magnetic field. We derive expressions for charge
and spin currents by means of the Keldysh non-equilibrium Green's functions
technique in linear order with respect to the time-dependent magnetic field
created by this precession. The coupling between the electronic spins and the
magnetization dynamics of the molecule creates inelastic tunneling processes
which contribute to the spin currents. The inelastic spin currents, in turn,
generate a spin-transfer torque acting on the molecular spin. This back-action
includes a contribution to the Gilbert damping and a modification of the
precession frequency. The Gilbert damping coefficient can be controlled by the
bias and gate voltages or via the external magnetic field and has a
non-monotonic dependence on the tunneling rates.",1211.3611v2
2012-11-24,Effects of Quantum Error Correction on Entanglement Sudden Death,"We investigate the effects of error correction on non-local quantum coherence
as a function of time, extending the study by Sainz and Bj\""ork. We consider
error correction of amplitude damping, pure phase damping and combinations of
amplitude and phase damping as they affect both fidelity and quantum
entanglement. Initial two-qubit entanglement is encoded in arbitrary real
superpositions of both \Phi-type and \Psi-type Bell states. Our main focus is
on the possibility of delay or prevention of ESD (early stage decoherence, or
entanglement sudden death). We obtain the onset times for ESD as a function of
the state-superposition mixing angle. Error correction affects entanglement and
fidelity differently, and we exhibit initial entangled states for which error
correction increases fidelity but decreases entanglement, and vice versa.",1211.5654v2
2012-12-04,Polarization dependence of phonon influences in exciton-biexciton quantum dot systems,"We report on a strong dependence of the phonon-induced damping of Rabi
dynamics in an optically driven exciton-biexciton quantum dot system on the
polarization of the exciting pulse. While for a fixed pulse intensity the
damping is maximal for linearly polarized excitation, it decreases with
increasing ellipticity of the polarization. This finding is most remarkable
considering that the carrier-phonon coupling is spin-independent. In addition
to simulations based on a numerically exact real-time path integral approach,
we present an analysis within a weak coupling theory that allows for analytical
expressions for the pertinent damping rates. We demonstrate that an efficient
coupling to the biexciton state is of central importance for the reported
polarization dependencies. Further, we discuss influences of various system
parameters and show that for finite biexciton binding energies Rabi scenarios
differ qualitatively from the widely studied two-level dynamics.",1212.0642v1
2012-12-10,Heat-induced damping modification in YIG/Pt hetero-structures,"We experimentally demonstrate the manipulation of magnetization relaxation
utilizing a temperature difference across the thickness of an yttrium iron
garnet/platinum (YIG/Pt) hetero-structure: the damping is either increased or
decreased depending on the sign of the temperature gradient. This effect might
be explained by a thermally-induced spin torque on the magnetization
precession. The heat-induced variation of the damping is detected by microwave
techniques as well as by a DC voltage caused by spin pumping into the adjacent
Pt layer and the subsequent conversion into a charge current by the inverse
spin Hall effect.",1212.2073v1
2012-12-13,Surface plasmon polaritons in a semi-bounded degenerate plasma: role of spatial dispersion and collisions,"Surface plasmon polaritons (SPPs) in a semi-bounded degenerate plasma (e.g.,
a metal) are studied using the quasiclassical mean-field kinetic model, taking
into account the spatial dispersion of the plasma (due to quantum degeneracy of
electrons) and electron-ion (electron-lattice, for metals) collisions. SPP
dispersion and damping are obtained in both retarded ($\omega/k_z\sim c$) and
non-retarded ($\omega/k_z\ll c$) regions, as well as in between. It is shown
that the plasma spatial dispersion significantly affects the properties of
SPPs, especially at short wavelengths (less than the collisionless skin depth,
$\lambda\lesssim c/\omega_{pe}$). Namely, the collisionless (Landau) damping of
SPPs (due to spatial dispersion) is comparable to the purely collisional
(Ohmic) damping (due to electron-lattice collisions) in a wide range of SPP
wavelengths, e.g., from $\lambda\sim20$ nm to $\lambda\sim0.8$ nm for SPP in
gold at T=293 K, and from $\lambda\sim400$ nm to $\lambda\sim0.7$ nm for SPPs
in gold at T=100 K. The spatial dispersion is also shown to affect, in a
qualitative way, the dispersion of SPPs at short wavelengths $\lambda\lesssim
c/\omega_{pe}$.",1212.3040v1
2012-12-13,Branching of quasinormal modes for nearly extremal Kerr black holes,"We show that nearly extremal Kerr black holes have two distinct sets of
quasinormal modes, which we call zero-damping modes (ZDMs) and damped modes
(DMs). The ZDMs exist for all harmonic indices $l$ and $m \ge 0$, and their
frequencies cluster onto the real axis in the extremal limit. The DMs have
nonzero damping for all black hole spins; they exist for all counterrotating
modes ($m<0$) and for corotating modes with $0\leq \mu\lesssim \mu_c=0.74$ (in
the eikonal limit), where $\mu\equiv m/(l+1/2)$. When the two families coexist,
ZDMs and DMs merge to form a single set of quasinormal modes as the black hole
spin decreases. Using the effective potential for perturbations of the Kerr
spacetime, we give intuitive explanations for the absence of DMs in certain
areas of the spectrum and for the branching of the spectrum into ZDMs and DMs
at large spins.",1212.3271v1
2012-12-31,Effects of lateral device size and material properties on the ferromagnetic resonance response of spinwave eigen-modes in magnetic devices,"We analyze the effects of lateral device size and magnetic material
parameters on the ferromagnetic resonance (FMR) response. Results presented are
directly relevant to widely used FMR experimental techniques for extracting
magnetic parameters from thin films, the results of which are often assumed to
carry over to corresponding nanometer-sized patterned devices. We show that
there can be significant variation in the FMR response with device size, and
that the extent of the variation depends on the magnetic material properties.
This explains, for example, why different experiments along these lines have
yielded different size-dependent trends from damping measurements. Observed
trends with increasing size and different material parameters are explained
through the evolution of three distinct eigen-modes, demonstrating the
respective roles of demagnetization and exchange. It is also shown that there
is a crossover of dominant eigen-modes in the response signal, accompanied by
conjugating edge-type modes, leading to evident effects in measured linewidth
and damping. Among the sizes considered, in higher saturation magnetization, we
observe as much as a 40% increase in apparent damping, due solely to device
size variation.",1212.6835v1
2013-01-16,Gain-tunable optomechanical cooling in a laser cavity,"We study the optical cooling of the resonator mirror in a
cavity-optomechanical system that contains an optical gain medium. We find that
the optical damping rate is vanishingly small for an incoherently pumped laser
above threshold. In the presence of an external coherent drive however, the
optical damping rate can be enhanced substantially with respect to that of a
passive cavity. We show that the strength of the incoherent pump provides a
conduit to tune the damping rate and the minimum attainable phonon number with
the same radiation pressure force, and the latter can be lowered from that of a
passive cavity if the thermal contribution is nonnegligible. We also show that
the system can undergo a transition from the weak optomechanical coupling
regime to the strong optomechanical coupling regime as the incoherent pump
strength is varied.",1301.3762v2
2013-01-18,Adiabatic stability under semi-strong interactions: The weakly damped regime,"We rigorously derive multi-pulse interaction laws for the semi-strong
interactions in a family of singularly-perturbed and weakly-damped
reaction-diffusion systems in one space dimension. Most significantly, we show
the existence of a manifold of quasi-steady N-pulse solutions and identify a
""normal-hyperbolicity"" condition which balances the asymptotic weakness of the
linear damping against the algebraic evolution rate of the multi-pulses. Our
main result is the adiabatic stability of the manifolds subject to this normal
hyperbolicity condition. More specifically, the spectrum of the linearization
about a fixed N-pulse configuration contains essential spectrum that is
asymptotically close to the origin as well as semi-strong eigenvalues which
move at leading order as the pulse positions evolve. We characterize the
semi-strong eigenvalues in terms of the spectrum of an explicit N by N matrix,
and rigorously bound the error between the N-pulse manifold and the evolution
of the full system, in a polynomially weighted space, so long as the
semi-strong spectrum remains strictly in the left-half complex plane, and the
essential spectrum is not too close to the origin.",1301.4466v1
2013-01-24,Spin transport parameters in metallic multilayers determined by ferromagnetic resonance measurements of spin pumping,"We measured spin transport in nonferromagnetic (NM) metallic multilayers from
the contribution to damping due to spin pumping from a ferromagnetic Co90Fe10
thin film. The multilayer stack consisted of NM1/NM2/Co90Fe10(2 nm)/NM2/NM3
with varying NM materials and thicknesses. Using conventional theory for one
dimensional diffusive spin transport in metals, we show that the effective
damping due to spin pumping can be strongly affected by the spin transport
properties of each NM in the multilayer, which permits the use of damping
measurements to accurately determine the spin transport properties of the
various NM layers in the full five-layer stack. We find that due to its high
electrical resistivity, amorphous Ta is a poor spin conductor, in spite of a
short spin-diffusion length of 1.0 nm, and that Pt is an excellent spin
conductor by virtue of its low electrical resistivity and a spin diffusion
length of only 0.5 nm. Spin Hall effect measurements may have underestimated
the spin Hall angle in Pt by assuming a much longer spin diffusion length.",1301.5861v1
2013-02-11,Low-damping epsilon-near-zero slabs: nonlinear and nonlocal optical properties,"We investigate second harmonic generation, low-threshold multistability,
all-optical switching, and inherently nonlocal effects due to the free-electron
gas pressure in an epsilon-near-zero (ENZ) metamaterial slab made of
cylindrical, plasmonic nanoshells illuminated by TM-polarized light. Damping
compensation in the ENZ frequency region, achieved by using gain medium inside
the shells' dielectric cores, enhances the nonlinear properties. Reflection is
inhibited and the electric field component normal to the slab interface is
enhanced near the effective pseudo-Brewster angle, where the effective
\epsilon-near-zero condition triggers a non-resonant, impedance-matching
phenomenon. We show that the slab displays a strong effective, spatial
nonlocality associated with leaky modes that are mediated by the compensation
of damping. The presence of these leaky modes then induces further spectral and
angular conditions where the local fields are enhanced, thus opening new
windows of opportunity for the enhancement of nonlinear optical processes.",1302.2392v1
2013-02-14,A Matlab toolbox for fractional relaxation-oscillation equations,"Stress relaxation and oscillation damping of complex viscoelastic media often
manifest history- and path-dependent physical behaviors and cannot accurately
be described by the classical models. Recent research found that fractional
derivative models can characterize such complex relaxation and damping.
However, to our best knowledge, easy-to-use numerical software is not available
for fractional relaxation-oscillation (FRO) equations. This paper is to
introduce an open source free Matlab toolbox which we developed in recent years
for numerical solution of the FRO equations. This FRO toolbox uses the
predictor-corrector approach for the discretization of time fractional
derivative, and non-expert users can accurately solve fractional
relaxation-oscillation equations via a friendly graphical user interface.
Compared with experimental data, our numerical experiments show that the FRO
toolbox is highly efficient and accurate to simulate viscoelastic stress
relaxation and damped vibration. This free toolbox will help promote the
research and practical use of fractional relaxation-oscillation equations.",1302.3384v1
2013-03-11,The Analysis of Long-Term Frequency and Damping Wandering in Buildings Using the Random Decrement Technique,"The characterization and monitoring of buildings is an issue that has
attracted the interest of many sectors over the last two decades. With the
increasing use of permanent, continuous and real-time networks, ambient
vibrations can provide a simple tool for the identification of dynamic building
parameters. This study is focused on the long-term variation of frequency and
damping in several buildings, using the Random Decrement Technique (RDT). RDT
provides a fast, robust and accurate long-term analysis and improves the
reliability of frequency and damping measurements for structural health
monitoring. This reveals particularly useful information in finding out
precisely how far changes in modal parameters can be related to changes in
physical properties. This paper highlights the reversible changes of the
structure's dynamic parameters, correlated with external forces, such as
temperature and exposure to the sun. Contrasting behaviors are observed,
including correlation and anti-correlation with temperature variations.",1303.2642v1
2013-03-21,Optimizing atomic resolution of force microscopy in ambient conditions,"Ambient operation poses a challenge to AFM because in contrast to operation
in vacuum or liquid environments, the cantilever dynamics change dramatically
from oscillating in air to oscillating in a hydration layer when probing the
sample. We demonstrate atomic resolution by imaging of the KBr(001) surface in
ambient conditions by frequency-modulation atomic force microscopy with a
cantilever based on a quartz tuning fork (qPlus sensor) and analyze both long-
and short-range contributions to the damping. The thickness of the hydration
layer increases with relative humidity, thus varying humidity enables us to
study the in uence of the hydration layer thickness on cantilever damping.
Starting with measurements of damping versus amplitude, we analyzed the signal
and the noise characteristics at the atomic scale. We then determined the
optimal amplitude which enabled us to acquire high-quality atomically resolved
images.",1303.5204v2
2013-04-10,Current Sheets and Collisionless Damping in Kinetic Plasma Turbulence,"We present the first study of the formation and dissipation of current sheets
at electron scales in a wave-driven, weakly collisional, 3D kinetic turbulence
simulation. We investigate the relative importance of dissipation associated
with collisionless damping via resonant wave-particle interactions versus
dissipation in small-scale current sheets in weakly collisional plasma
turbulence. Current sheets form self-consistently from the wave-driven
turbulence, and their filling fraction is well correlated to the electron
heating rate. However, the weakly collisional nature of the simulation
necessarily implies that the current sheets are not significantly dissipated
via Ohmic dissipation. Rather, collisionless damping via the Landau resonance
with the electrons is sufficient to account for the measured heating as a
function of scale in the simulation, without the need for significant Ohmic
dissipation. This finding suggests the possibility that the dissipation of the
current sheets is governed by resonant wave-particle interactions and that the
locations of current sheets correspond spatially to regions of enhanced
heating.",1304.2958v2
2013-04-22,Constant residual electrostatic electron plasma mode in Vlasov-Ampere system,"In a collisionless Vlasov-Poisson (V-P) electron plasma system, two types of
modes for electric field perturbation exist: the exponentially Landau damped
electron plasma waves and the initial-value sensitive ballistic modes. Here,
the V-P system is modified slightly to a Vlasov-Ampere (V-A) system. A new
constant residual mode is revealed. Mathematically, this mode comes from the
Laplace transform of an initial electric field perturbation, and physically
represents that an initial perturbation (e.g., external electric field
perturbation) would not be damped away. Thus, this residual mode is more
difficult to be damped than the ballistic mode. [Physics of Plasmas 20, 112108
(2013); doi: 10.1063/1.4831761]",1304.5883v2
2013-04-23,Existence and non-existence of breather solutions in damped and driven nonlinear lattices,"We investigate the existence of spatially localised solutions, in the form of
discrete breathers, in general damped and driven nonlinear lattice systems of
coupled oscillators. Conditions for the exponential decay of the difference
between the maximal and minimal amplitudes of the oscillators are provided
which proves that initial non-uniform spatial patterns representing breathers
attain exponentially fast a spatially uniform state preventing the formation
and/or preservation of any breather solution at all. Strikingly our results are
generic in the sense that they hold for arbitrary dimension of the system, any
attractive interaction, coupling strength and on-site potential and general
driving fields. Furthermore, our rigorous quantitative results establish
conditions under which discrete breathers in general damped and driven
nonlinear lattices can exist at all and open the way for further research on
the emergent dynamical scenarios, in particular features of pattern formation,
localisation and synchronisation, in coupled cell networks.",1304.6370v3
2013-06-21,Inviscid damping and the asymptotic stability of planar shear flows in the 2D Euler equations,"We prove asymptotic stability of shear flows close to the planar Couette flow
in the 2D inviscid Euler equations on $\Torus \times \Real$. That is, given an
initial perturbation of the Couette flow small in a suitable regularity class,
specifically Gevrey space of class smaller than 2, the velocity converges
strongly in L^2 to a shear flow which is also close to the Couette flow. The
vorticity is asymptotically driven to small scales by a linear evolution and
weakly converges as $t \rightarrow \pm\infty$. The strong convergence of the
velocity field is sometimes referred to as inviscid damping, due to the
relationship with Landau damping in the Vlasov equations. This convergence was
formally derived at the linear level by Kelvin in 1887 and it occurs at an
algebraic rate first computed by Orr in 1907; our work appears to be the first
rigorous confirmation of this behavior on the nonlinear level.",1306.5028v3
2013-07-12,Spin injection from topological insulator tunnel-coupled to metallic leads,"We study theoretically helical edge states of 2D and 3D topological
insulators (TI) tunnel-coupled to metal leads and show that their transport
properties are strongly affected by contacts as the latter play a role of a
heat bath and induce damping and relaxation of electrons in the helical states
of TI. A simple structure that produces a pure spin current in the external
circuit is proposed. The current and spin current delivered to the external
circuit depend on relation between characteristic lengths: damping length due
to tunneling, contact length and, in case of 3D TI, mean free path and spin
relaxation length caused by momentum scattering. If the damping length due to
tunneling is the smallest one, then the electric and spin currents are
proportional to the conductance quantum in 2D TI, and to the conductance
quantum multiplied by the ratio of the contact width to the Fermi wavelength in
3D TI.",1307.3333v1
2013-07-19,Damping and non-linearity of a levitating magnet in rotation above a superconductor,"We study the dissipation of moving magnets in levitation above a
superconductor. The rotation motion is analyzed using optical tracking
techniques. It displays a remarkable regularity together with long damping time
up to several hours. The magnetic contribution to the damping is investigated
in detail by comparing 14 distinct magnetic configurations, and points towards
amplitude-dependent dissipation mechanisms. The non-linear dynamics of the
mechanical rotation motion is also revealed and described with an effective
Duffing model. The obtained picture of the coupling of levitating magnets to
their environment sheds light on their potential as ultra-low dissipation
mechanical oscillators for high precision physics.",1307.5155v1
2013-07-19,Perfect squeezing by damping modulation in circuit quantum electrodynamics,"Dissipation-driven quantum state engineering uses the environment to steer
the state of quantum systems and preserve quantum coherence in the steady
state. We show that modulating the damping rate of a microwave resonator
generates a vacuum squeezed state of arbitrary squeezing strength, thereby
constituting a mechanism allowing perfect squeezing. Given the recent
experimental realizations in circuit QED of a microwave resonator with a
tunable damping rate [Yin et al., Phys. Rev. Lett. 110, 107001 (2013)],
superconducting circuits are an ideal playground to implement this technique.
By dispersively coupling a qubit to the microwave resonator, it is possible to
obtain qubit-state dependent squeezing.",1307.5311v2
2013-07-27,"Charge-carrier-induced frequency renormalization, damping and heating of vibrational modes in nanoscale junctions","In nanoscale junctions the interaction between charge carriers and the local
vibrations results in renormalization, damping and heating of the vibrational
modes. We here formulate a nonequilibrium Green's functions based theory to
describe such effects. Studying a generic junction model with an off-resonant
electronic level, we find a strong bias dependence of the frequency
renormalization and vibrational damping accompanied by pronounced nonlinear
vibrational heating in junctions with intermediate values of the coupling to
the leads. Combining our theory with ab-initio calculations we furthermore show
that the bias dependence of the Raman shifts and linewidths observed
experimentally in an OPV3 junction [D. Ward et al., Nature Nano. 6, 33 (2011)]
may be explained by a combination of dynamic carrier screening and molecular
charging.",1307.7288v3
2013-07-30,Phase retrapping in a pointlike $\varphi$ Josephson junction: the Butterfly effect,"We consider a $\varphi$ Josephson junction, which has a bistable zero-voltage
state with the stationary phases $\psi=\pm\varphi$. In the non-zero voltage
state the phase ""moves"" viscously along a tilted periodic double-well
potential. When the tilting is reduced quasistatically, the phase is retrapped
in one of the potential wells. We study the viscous phase dynamics to determine
in which well ($-\varphi$ or $+\varphi$) the phase is retrapped for a given
damping, when the junction returns from the finite-voltage state back to
zero-voltage state. In the limit of low damping the $\varphi$ Josephson
junction exhibits a butterfly effect --- extreme sensitivity of the destination
well on damping. This leads to an impossibility to predict the destination
well.",1307.8042v1
2013-10-13,What the Timing of Millisecond Pulsars Can Teach us about Their Interior,"The cores of compact stars reach the highest densities in nature and
therefore could consist of novel phases of matter. We demonstrate via a
detailed analysis of pulsar evolution that precise pulsar timing data can
constrain the star's composition, through unstable global oscillations
(r-modes) whose damping is determined by microscopic properties of the
interior. If not efficiently damped, these modes emit gravitational waves that
quickly spin down a millisecond pulsar. As a first application of this general
method, we find that ungapped interacting quark matter is consistent with both
the observed radio and x-ray data, whereas for ordinary nuclear matter some
additional enhanced damping mechanism is required.",1310.3524v2
2013-11-28,Conservative effects in spin-transfer-driven magnetization dynamics,"It is shown that under appropriate conditions spin-transfer-driven
magnetization dynamics in a single-domain nanomagnet is conservative in nature
and admits a specific integral of motion, which is reduced to the usual
magnetic energy when the spin current goes to zero. The existence of this
conservation law is connected to the symmetry properties of the dynamics under
simultaneous inversion of magnetisation and time. When one applies an external
magnetic field parallel to the spin polarization, the dynamics is transformed
from conservative into dissipative. More precisely, it is demonstrated that
there exists a state function such that the field induces a monotone relaxation
of this function toward its minima or maxima, depending on the field
orientation. These results hold in the absence of intrinsic damping effects.
When intrinsic damping is included in the description, a competition arises
between field-induced and damping-induced relaxations, which leads to the
appearance of limit cycles, that is, of magnetization self-oscillations.",1311.7344v1
2013-12-05,The initial condition problems of damped quantum harmonic oscillator,"We investigate the exact dynamics of the damped quantum harmonic oscillator
under the (un)correlated initial conditions. The master equation is generalized
to the cases of the arbitrary factorized state and/or Gaussian state. We show
that the variances of the factorized Gaussian state do not sensitively depend
on the initial oscillator-bath correlation, which however can remarkably affect
the mean values even at high temperature. We also illustrate that the
correlations among the factorized states still give rise to the initial dips
during the purity evolutions, which can be smoothed out by increasing the
amount of correlation to some extent. We finally study the effects of repeated
measurements on the time evolution of the damped oscillator analytically, which
are compared with the weak coupling results to indicate that they give rather
different transient behaviors even for an intermediate coupling.",1312.1454v1
2013-12-13,Optical variability of quasars: a damped random walk,"A damped random walk is a stochastic process, defined by an exponential
covariance matrix that behaves as a random walk for short time scales and
asymptotically achieves a finite variability amplitude at long time scales.
Over the last few years, it has been demonstrated, mostly but not exclusively
using SDSS data, that a damped random walk model provides a satisfactory
statistical description of observed quasar variability in the optical
wavelength range, for rest-frame timescales from 5 days to 2000 days. The
best-fit characteristic timescale and asymptotic variability amplitude scale
with the luminosity, black hole mass, and rest wavelength, and appear
independent of redshift. In addition to providing insights into the physics of
quasar variability, the best-fit model parameters can be used to efficiently
separate quasars from stars in imaging surveys with adequate long-term
multi-epoch data, such as expected from LSST.",1312.3966v1
2013-12-25,Non-linear damping of visco-resistive Alfven waves in solar spicules,"Interaction of Alfven waves with plasma inhomogeneities generates phase
mixing which can lead to dissipate Alfven waves and to heat the solar plasma.
Here we study the dissipation of Alfven waves by phase mixing due to viscosity
and resistivity variations with height. We also consider nonlinear
magnetohydrodynamic (MHD) equations in our theoretical model. Non-linear terms
of MHD equations include perturbed velocity, magnetic field, and density. To
investigate the damping of Alfven waves in a stratified atmosphere of solar
spicules, we solve the non-linear MHD equations in the x-z plane. Our
simulations show that the damping is enhanced due to viscosity and resistivity
gradients. Moreover, energy variations is influenced due to nonlinear terms in
MHD equations.",1312.7866v1
2013-12-31,A novel variability-based method for quasar selection: evidence for a rest frame ~54 day characteristic timescale,"We compare quasar selection techniques based on their optical variability
using data from the Catalina Real-time Transient Survey (CRTS). We introduce a
new technique based on Slepian wavelet variance (SWV) that shows comparable or
better performance to structure functions and damped random walk models but
with fewer assumptions. Combining these methods with WISE mid-IR colors
produces a highly efficient quasar selection technique which we have validated
spectroscopically. The SWV technique also identifies characteristic timescales
in a time series and we find a characteristic rest frame timescale of ~54 days,
confirmed in the light curves of ~18000 quasars from CRTS, SDSS and MACHO data,
and anticorrelated with absolute magnitude. This indicates a transition between
a damped random walk and $P(f) \propto f^{-1/3}$ behaviours and is the first
strong indication that a damped random walk model may be too simplistic to
describe optical quasar variability.",1401.1785v1
2014-02-09,Manipulation of tripartite-to-bipartite entanglement localization under quantum noises and its application to entanglement distribution,"This paper is to investigate the effects of quantum noises on entanglement
localization by taking an example of reducing a three-qubit
Greenberger-Horne-Zeilinger (GHZ) state to a two-qubit entangled state. We
consider, respectively, two types of quantum decoherence, i.e.,
amplitude-damping and depolarizing decoherence, and explore the best von
Neumann measurements on one of three qubits of the triple GHZ state for making
the amount of entanglement of the collapsed bipartite state be as large as
possible. The results indicate that different noises have different impacts on
entanglement localization, and that the optimal strategy for reducing a
three-qubit GHZ state to a two-qubit one via local measurements and classical
communications in the amplitude-damping case is different from that in the
noise-free case. We also show that the idea of entanglement localization could
be utilized to improve the quality of bipartite entanglement distributing
through amplitude-damping channels. These findings might shed a new light on
entanglement manipulations and transformations.",1402.1914v2
2014-02-25,Thermodynamic anomalies in the presence of dissipation: from the free particle to the harmonic oscillator,"A free particle coupled to a heat bath can exhibit a number of thermodynamic
anomalies like a negative specific heat or reentrant classicality. These
low-temperature phenomena are expected to be modified at very low temperatures
where finite-size effects associated with the discreteness of the energy
spectrum become relevant. In this paper, we explore in which form the
thermodynamic anomalies of the free damped particle appear for a damped
harmonic oscillator. Since the discreteness of the oscillator's energy spectrum
is fully accounted for, the results are valid for arbitrary temperatures. As
expected, they are in agreement with the third law of thermodynamics and
indicate how the thermodynamic anomalies of the free damped particle can be
reconciled with the third law. Particular attention is paid to the transition
from the harmonic oscillator to the free particle when the limit of the
oscillator frequency to zero is taken.",1402.6221v1
2014-02-26,Magneto-elastic modes and lifetime of magnons in thin yttrium-iron garnet films,"We calculate the effects of the spin-lattice coupling on the magnon spectrum
of thin ferromagnetic films consisting of the magnetic insulator yttrium-iron
garnet. The magnon-phonon hybridisation generates a characteristic minimum in
the spin dynamic structure factor which quantitatively agrees with recent
Brillouin light scattering experiments. We also show that at room temperature
the phonon contribution to the magnon damping exhibits a rather complicated
momentum dependence: In the exchange regime the magnon damping is dominated by
Cherenkov type scattering processes, while in the long-wavelength dipolar
regime these processes are subdominant and the magnon damping is two orders of
magnitude smaller. We supplement our calculations by actual measurements of the
magnon relaxation in the dipolar regime. Our theory provides a simple
explanation of a recent experiment probing the different temperatures of the
magnon and phonon gases in yttrium-iron garnet.",1402.6575v2
2014-02-28,A new way to evaluate x-ray Brillouin scattering data,"Making use of the classical second moment sum rule, it is possible to convert
a series of constant-Q x-ray Brillouin scattering scans (Q momentum transfer)
into a series of constant frequency scans over the measured $Q$ range. The
method is applied to literature results for the phonon dispersion in liquid
vitreous silica and in glassy polybutadiene. It turns out that the constant
frequency scans are again well fitted by the damped harmonic oscillator
function, but now in terms of a Q-independent phonon damping depending
exclusively on the frequency. At low frequency, the sound velocity and the
damping of both evaluations agree, but at higher frequencies one gets
significant differences. The results in silica suggest a new interpretation of
x-ray Brillouin data in terms of a strong mixing of longitudinal and transverse
phonons toward higher frequencies. The results in polybutadiene enlighten the
crossover from Brillouin to Umklapp scattering.",1402.7237v1
2014-08-13,Probing dense matter in compact star cores with radio pulsar data,"Astrophysical observations of compact stars provide, in addition to collider
experiments, the other big source of information on matter under extreme
conditions. The largest and most precise data set about neutron stars is the
timing data of radio pulsars. We show how this unique data can be used to learn
about the ultra-dense matter in the compact star interior. The method relies on
astro-seismology based on special global oscillation modes (r-modes) that emit
gravitational waves. They would prevent pulsars from spinning with their
observed high frequencies, unless the damping of these modes, determined by the
microscopic properties of matter, can prevent this. We show that for each form
of matter there is a distinct region in a frequency/spindown-rate diagram where
r-modes can be present. We find that stars containing ungapped quark matter are
consistent with both the observed radio and x-ray data, whereas, even when
taking into account the considerable uncertainties, neutron star models with
standard viscous damping are inconsistent with both data sets and additional
damping mechanisms would be required.",1408.3152v1
2014-08-25,Spin-Scattering Rates in Metallic Thin Films Measured by Ferromagnetic Resonance Damping Enhanced by Spin-Pumping,"We determined the spin-transport properties of Pd and Pt thin films by
measuring the increase in ferromagnetic resonance damping due to spin-pumping
in ferromagnetic (FM)-nonferromagnetic metal (NM) multilayers with varying NM
thicknesses. The increase in damping with NM thickness depends strongly on both
the spin- and charge-transport properties of the NM, as modeled by diffusion
equations that include both momentum- and spin-scattering parameters. We use
the analytical solution to the spin-diffusion equations to obtain
spin-diffusion lengths for Pt and Pd. By measuring the dependence of
conductivity on NM thickness, we correlate the charge- and spin-transport
parameters, and validate the applicability of various models for
momentum-scattering and spin-scattering rates in these systems: constant,
inverse-proportional (Dyakanov-Perel), and linear-proportional (Elliot-Yafet).
We confirm previous reports that the spin-scattering time can be shorter than
the momentum scattering time in Pt, and the Dyakanov-Perel-like model is the
best fit to the data.",1408.5921v2
2014-08-27,Quasi-particle Lifetime in a Mixture of Bose and Fermi Superfluids,"In this letter, to reveal the effect of quasi-particle interactions in a
Bose-Fermi superfluid mixture, we consider the lifetime of quasi-particle of
Bose superfluid due to its interaction with quasi-particles in Fermi
superfluid. We find that this damping rate, i.e. inverse of the lifetime, has
quite different threshold behavior at the BCS and the BEC side of the Fermi
superfluid. The damping rate is a constant nearby the threshold momentum in the
BCS side, while it increases rapidly in the BEC side. This is because in the
BCS side the decay processe is restricted by constant density-of-state of
fermion quasi-particle nearby Fermi surface, while such a restriction does not
exist in the BEC side where the damping process is dominated by bosonic
quasi-particles of Fermi superfluid. Our results are related to collective mode
experiment in recently realized Bose-Fermi superfluid mixture.",1408.6419v1
2014-09-04,A numerical study of the pull-in instability in some free boundary models for MEMS,"In this work we numerically compute the bifurcation curve of stationary
solutions for the free boundary problem for MEMS in one space dimension. It has
a single turning point, as in the case of the small aspect ratio limit. We also
find a threshold for the existence of global-in-time solutions of the evolution
equation given by either a heat or a damped wave equation. This threshold is
what we term the dynamical pull-in value: it separates the stable operation
regime from the touchdown regime. The numerical calculations show that the
dynamical threshold values for the heat equation coincide with the static
values. For the damped wave equation the dynamical threshold values are smaller
than the static values. This result is in agreement with the observations
reported for a mass-spring system studied in the engineering literature. In the
case of the damped wave equation, we also show that the aspect ratio of the
device is more important than the inertia in the determination of the pull-in
value.",1409.1291v2
2014-09-15,"Direct path from microscopic mechanics to Debye shielding, Landau damping, and wave-particle interaction","The derivation of Debye shielding and Landau damping from the $N$-body
description of plasmas is performed directly by using Newton's second law for
the $N$-body system. This is done in a few steps with elementary calculations
using standard tools of calculus, and no probabilistic setting. Unexpectedly,
Debye shielding is encountered together with Landau damping. This approach is
shown to be justified in the one-dimensional case when the number of particles
in a Debye sphere becomes large. The theory is extended to accommodate a
correct description of trapping and chaos due to Langmuir waves. Shielding and
collisional transport are found to be two related aspects of the repulsive
deflections of electrons, in such a way that each particle is shielded by all
other ones while keeping in uninterrupted motion.",1409.4323v1
2014-09-19,Damping of metallized bilayer nanomechanical resonators at room temperature,"We investigate the influence of gold thin-films subsequently deposited on a
set of initially bare, doubly clamped, high-stress silicon nitride string
resonators at room temperature. Analytical expressions for resonance frequency,
quality factor and damping for both in- and out-of-plane flexural modes of the
bilayer system are derived, which allows for the determination of effective
elastic parameters of the composite structure from our experimental data. We
find the inverse quality factor to scale linearly with the gold film thickness,
indicating that the overall damping is governed by losses in the metal.
Correspondingly, the mechanical linewidth increases by more than one order of
magnitude compared to the bare silicon nitride string resonator. Furthermore,
we extract mechanical quality factors of the gold film for both flexural modes
and show that they can be enhanced by complete deposition of the metal in a
single step, suggesting that surface and interface losses play a vital role in
metal thin-films.",1409.5670v1
2014-10-09,Non-Fermi-liquid behavior and anomalous suppression of Landau damping in layered metals close to ferromagnetism,"We analyse the low-energy physics of nearly ferromagnetic metals in two
spatial dimensions using the functional renormalization group technique. We
find a new low-energy fixed point, at which the fermionic (electron-like)
excitations are non-Fermi-liquid ($z_f = 13/10$) and the magnetic fluctuations
exhibit an anomalous Landau damping whose rate vanishes as $\Gamma_{\bf q} \sim
\vert {\bf q} \vert^{3/5}$ in the low-$\vert {\bf q} \vert$ limit. We discuss
this renormalization of the Landau-damping exponent, which is the major novel
prediction of our work, and highlight the possible link between that
renormalization and neutron-scattering data on UGe$_2$ and related compounds.
Implications of our analysis for YFe$_2$Al$_{10}$ are also discussed.",1410.2539v3
2014-10-09,Special mean motion resonance pairs: Mimas-Tethys and Titan-Hyperion,"Five pairs of large solar system satellites occupy first order mean-motion
resonances (MMRs). Among these, the pairs of Mimas-Tethys and Titan-Hyperion
are special. They are located much deeper in resonance than the others and
their critical arguments librate with much greater amplitudes. These
characteristics are traced to the insignificant damping, over $\Gyr$
timescales, of Mimas's orbital inclination and Hyperion's orbital eccentricity.
Absent that, these resonances would not survive. Instead their librations would
be overstable and escape from resonance would occur on the relevant damping
time. Unlike the aforementioned MMRs, those involving Enceladus-Dione,
Io-Europa, and Europa-Ganymede are limited by eccentricity damping. They must
either remain at the shallow depths they currently occupy, or, if they venture
deeper, retreat after a limited time. The latter seems almost certain for
Enceladus-Dione and quite likely for the others, We examine the MMRs involving
Mimas-Tethys and Titan-Hyperion under the assumption that they formed as a
result of convergent migration. Capture probabilities are $\sim 6\%$ for the
former and $100\%$ for the latter. The possibility of collisional excitation of
their large librations is investigated but largely discounted.",1410.2648v1
2014-11-13,Stability and bifurcation for the Kuramoto model,"We study the mean-field limit of the Kuramoto model of globally coupled
oscillators. By studying the evolution in Fourier space and understanding the
domain of dependence, we show a global stability result. Moreover, we can
identify function norms to show damping of the order parameter for velocity
distributions and perturbations in $\mathcal{W}^{n,1}$ for $n > 1$. Finally,
for sufficiently regular velocity distributions we can identify exponential
decay in the stable case and otherwise identify finitely many eigenmodes. For
these eigenmodes we can show a center-unstable manifold reduction, which gives
a rigorous tool to obtain the bifurcation behaviour. The damping is similar to
Landau damping for the Vlasov equation.",1411.3752v3
2014-11-26,A singular finite element technique for calculating continuum damping of Alfvén eigenmodes,"Damping due to continuum resonances can be calculated using dissipation-less
ideal magnetohydrodynamics (MHD) provided that the poles due to these
resonances are properly treated. We describe a singular finite element
technique for calculating the continuum damping of Alfv\'{e}n waves. A
Frobenius expansion is used to determine appropriate finite element basis
functions on an inner region surrounding a pole due to the continuum resonance.
The location of the pole due to the continuum resonance and mode frequency are
calculated iteratively using a Galerkin method. This method is used to find the
complex frequency and mode structure of a toroidicity-induced Alfv\'{e}n
eigenmode (TAE) in a large aspect ratio circular tokamak and are shown to agree
closely with a complex contour technique.",1411.7111v1
2014-11-26,Energy decay for a locally undamped wave equation,"We study the decay rate for the energy of solutions of a damped wave equation
in a situation where the Geometric Control Condition is violated. We assume
that the set of undamped trajectories is a flat torus of positive codimension
and that the metric is locally flat around this set. We further assume that the
damping function enjoys locally a prescribed homogeneity near the undamped set
in traversal directions. We prove a sharp decay estimate at a polynomial rate
that depends on the homogeneity of the damping function. Our method relies on a
refined microlocal analysis linked to a second microlocalization procedure to
cut the phase space into tiny regions respecting the uncertainty principle but
way too small to enter a standard semi-classical analysis localization. Using a
multiplier method, we obtain the energy estimates in each region and we then
patch the microlocal estimates together.",1411.7271v1
2014-12-05,Calculating linear response functions for finite temperatures on the basis of the alloy analogy model,"A scheme is presented that is based on the alloy analogy model and allows to
account for thermal lattice vibrations as well as spin fluctuations when
calculating response quantities in solids. Various models to deal with spin
fluctuations are discussed concerning their impact on the resulting temperature
dependent magnetic moment, longitudinal conductivity and Gilbert damping
parameter. It is demonstrated that using the Monte Carlo (MC) spin
configuration as an input, the alloy analogy model is capable to reproduce
results of MC simulations on the average magnetic moment within all spin
fluctuation models under discussion. On the other hand, response quantities are
much more sensitive to the spin fluctuation model. Separate calculations
accounting for either the thermal effect due to lattice vibrations or spin
fluctuations show their comparable contributions to the electrical conductivity
and Gilbert damping. However, comparison to results accounting for both thermal
effects demonstrate violation of Matthiessen's rule, showing the non-additive
effect of lattice vibrations and spin fluctuations. The results obtained for
bcc Fe and fcc Ni are compared with the experimental data, showing rather good
agreement for the temperature dependent electrical conductivity and Gilbert
damping parameter.",1412.1988v1
2014-12-05,Entanglement Dynamics of Quantum Oscillators Nonlinearly Coupled to Thermal Environments,"We study the asymptotic entanglement of two quantum harmonic oscillators
nonlinearly coupled to an environment. Coupling to independent baths and a
common bath are investigated. Numerical results obtained using the
Wangsness-Bloch-Redfield method are supplemented by analytical results in the
rotating wave approximation. The asymptotic negativity as function of
temperature, initial squeezing and coupling strength, is compared to results
for systems with linear system-reservoir coupling. We find that due to the
parity conserving nature of the coupling, the asymptotic entanglement is
considerably more robust than for the linearly damped cases. In contrast to
linearly damped systems, the asymptotic behavior of entanglement is similar for
the two bath configurations in the nonlinearly damped case. This is due to the
two-phonon system-bath exchange causing a supression of information exchange
between the oscillators via the bath in the common bath configuration at low
temperatures.",1412.1999v1
2014-12-08,The dispersion modification of electrostatic geodesic acoustic mode by electron geodesic drift current,"The past studies treated the perturbed distribution of circulating electrons
as adiabatic one when studying the dispersion relation of electrostatic
geodesic acoustic mode(GAM). In this paper, the flow of electron geodesic
current (FEGC) is added to modify this adiabatic distribution. Based on the
drift kinetic theory, it is found that FEGC obviously increases the magnitude
of the standard GAM's frequency and reduces its damping rate. The increase of
frequency results from the contribution of FEGC to the radial flow. The reason
for the reduction of damping rate is that when the effect of FEGC counts, the
new resonant velocity becomes much larger than ions thermal velocity with
equilibrium distribution obeying Maxwellian distribution, compared with
unmodified Landau resonant velocity. Especially, FEGC changes the characters of
the frequency and damping rate of low-frequency GAM as functions of safety
factor $q$ .",1412.2481v1
2014-12-10,Alfvenic Turbulence Beyond the Ambipolar Diffusion Scale,"We investigate the nature of the Alfv\'enic turbulence cascade in two fluid
MHD simulations in order to determine if turbulence is damped once the ion and
neutral species become decoupled at a critical scale called the ambipolar
diffusion scale (L$_{AD}$). Using mode decomposition to separate the three
classical MHD modes, we study the second order structure functions of the
Alfv\'en mode velocity field of both neutrals and ions in the reference frame
of the local magnetic field. On scales greater than L$_{AD}$ we confirm that
two fluid turbulence strongly resembles single fluid MHD turbulence. Our
simulations show that the behavior of two fluid turbulence becomes more complex
on scales less than L$_{AD}$. We find that Alfvenic turbulence can exist past
L$_{AD}$ when the turbulence is globally super-Alfv\'enic, with the ions and
neutrals forming separate cascades once decoupling has taken place. When
turbulence is globally sub-Alfvenic and hence strongly anisotropic with a large
separation between the parallel and perpendicular decoupling scales, turbulence
is damped at L$_{AD}$. We also find that the power spectrum of the kinetic
energy in the damped regime is consistent with a $k^{-4}$ scaling (in agreement
with the predictions of Lazarian, Vishniac & Cho 2004).",1412.3452v1
2015-01-19,"Linear wave action decay entailed by Landau damping in inhomogeneous, nonstationary and anisotropic plasma","This paper addresses the linear propagation of an electron wave in a
collisionless, inhomogeneous, nonstationary and anisotropic plasma. The plasma
is characterized by its distribution function, $f_H$, at zero order in the wave
amplitude. This distribution function, from which are derived all the
hydrodynamical quantities, may be chosen arbitrarily, provided that it solves
Vlasov equation. Then, from the linearized version of the electrons equation of
motion, and from Gauss law, is derived an envelope equation for the wave
amplitude, assumed to evolve over time and space scales much larger than the
oscillation periods of the wave. The envelope equation may be cast into an
equation for the the wave action, derived from Whitham's variational principle,
that demonstrates the action decay due to Landau damping. Moreover, the Landau
damping rate is derived at first order in the variations of the wave number and
frequency. As briefly discussed, this paper generalizes numerous previous works
on the subject, provides a theoretical basis for heuristic arguments regarding
the action decay, and also addresses the propagation of an externally driven
wave.",1501.04485v1
2015-01-23,"Response solutions for quasi-periodically forced, dissipative wave equations","We consider several models of nonlinear wave equations subject to very strong
damping and quasi-periodic external forcing. This is a singular perturbation,
since the damping is not the highest order term. We study the existence of
response solutions (i.e., quasi-periodic solutions with the same frequency as
the forcing). Under very general non-resonance conditions on the frequency, we
show the existence of asymptotic expansions of the response solution; moreover,
we prove that the response solution indeed exists and depends analytically on
$\varepsilon$ (where $\varepsilon$ is the inverse of the coefficient
multiplying the damping) for $\varepsilon$ in a complex domain, which in some
cases includes disks tangent to the imaginary axis at the origin. In other
models, we prove analyticity in cones of aperture $\pi/2$ and we conjecture it
is optimal. These results have consequences for the asymptotic expansions of
the response solutions considered in the literature. The proof of our results
relies on reformulating the problem as a fixed point problem, constructing an
approximate solution and studying the properties of iterations that converge to
the solutions of the fixed point problem.",1501.05979v1
2015-01-30,A large-scale magnetic shield with 10^6 damping at mHz frequencies,"We present a magnetically shielded environment with a damping factor larger
than one million at the mHz frequency regime and an extremely low field and
gradient over an extended volume. This extraordinary shielding performance
represents an improvement of the state of the art in damping the difficult
regime of very low-frequency distortions by more than an order of magnitude.
This technology enables a new generation of high precision measurements in
fundamental physics and metrology, including searches for new physics far
beyond the reach of accelerator-based experiments. We discuss the technical
realization of the shield with its improvements in design.",1501.07861v4
2015-02-01,A Study on the Impact of Wind Generation on the Stability of Electromechanical Oscillations,"Wind is becoming an increasingly significant source of energy in modern power
generation. Amongst existing technologies, Variable Speed Wind Turbines (VSWT)
equipped with Double Fed Induction Generators (DFIG) is widely deployed.
Consequently, power systems are now experiencing newer power flow patterns and
operating conditions. This paper investigates the impact of a DFIG based Wind
Farm (WF) on the stability of electromechanical oscillations. This is achieved
by performing modal analysis to evaluate the stability of a two-area power
network when subjected to different wind penetration levels and different
geographical installed locations. The approach via eigenvalues analysis
involves the design of voltage and Supplementary Damping Controllers (SDCs)
that contribute to network damping. The effect of Power System Stabilizer (PSS)
is also examined for several network conditions. Simulations demonstrate a
damping improvement up to 933% when the control systems are activated and the
system operates with 25% wind integration.",1502.00215v1
2015-02-05,Nonlinear analysis of magnetization dynamics excited by spin Hall effect,"We investigate the possibility of exciting self-oscillation in a
perpendicular ferromagnet by the spin Hall effect on the basis of a nonlinear
analysis of the Landau-Lifshitz-Gilbert (LLG) equation. In the self-oscillation
state, the energy supplied by the spin torque during a precession on a constant
energy curve should equal the dissipation due to damping. Also, the current to
balance the spin torque and the damping torque in the self-oscillation state
should be larger than the critical current to destabilize the initial state. We
find that the second condition in the spin Hall system is not satisfied by
deriving analytical solutions of the energy supplied by the spin transfer
effect and the dissipation due to the damping from the nonlinear LLG equation.
This indicates that the self-oscillation of a perpendicular ferromagnet cannot
be excited solely by the spin Hall torque.",1502.01420v2
2015-02-16,"Biomimetic Staggered Composites with Highly Enhanced Energy Dissipation: Design, Modeling, and Test","We investigate the damping enhancement in a class of biomimetic staggered
composites via a combination of design, modeling, and experiment. In total,
three kinds of staggered composites are designed by mimicking the structure of
bone and nacre. These composite designs are realized by 3D printing a rigid
plastic and a viscous elastomer simultaneously. Greatly-enhanced energy
dissipation in the designed composites is observed from both the experimental
results and theoretical prediction. The designed polymer composites have loss
modulus up to ~500 MPa, higher than most of the existing polymers. In addition,
their specific loss modulus (up to 0.43 $Km^2/s^2$) is among the highest of
damping materials. The damping enhancement is attributed to the large shear
deformation of the viscous soft matrix and the large strengthening effect from
the rigid inclusion phase.",1502.04568v1
2015-02-24,High Quality Yttrium Iron Garnet Grown by Room Temperature Pulsed Laser Deposition and Subsequent Annealing,"We have investigated recrystallization of amorphous Yttrium Iron Garnet (YIG)
by annealing in oxygen atmosphere. Our findings show that well below the
melting temperature the material transforms into a fully epitaxial layer with
exceptional quality, both structural and magnetic.\\ In ferromagnetic resonance
(FMR) ultra low damping and extremely narrow linewidth can be observed. For a
56 nm thick layer a damping constant of
$\alpha$=(6.63$\pm$1.50)$\cdot$10$^{-5}$ is found and the linewidth at 9.6 GHz
is as small as 1.30$\pm$0.05 Oe which are the lowest values for PLD grown thin
films reported so far. Even for a 20 nm thick layer a damping constant of
$\alpha$=(7.51$\pm$1.40)$\cdot$10$^{-5}$ is found which is the lowest value for
ultrathin films published so far. The FMR linewidth in this case is
3.49$\pm$0.10 Oe at 9.6 GHz. Our results not only present a method of
depositing thin film YIG of unprecedented quality but also open up new options
for the fabrication of thin film complex oxides or even other crystalline
materials.",1502.06724v2
2015-03-02,DAMPE silicon tracker on-board data compression algorithm,"The Dark Matter Particle Explorer (DAMPE) is an upcoming scientific satellite
mission for high energy gamma-ray, electron and cosmic rays detection. The
silicon tracker (STK) is a sub detector of the DAMPE payload with an excellent
position resolution (readout pitch of 242um), which measures the incident
direction of particles, as well as charge. The STK consists 12 layers of
Silicon Micro-strip Detector (SMD), equivalent to a total silicon area of
6.5m$^2$. The total readout channels of the STK are 73728, which leads to a
huge amount of raw data to be dealt. In this paper, we focus on the on-board
data compression algorithm and procedure in the STK, which was initially
verified by cosmic-ray measurements.",1503.00415v1
2015-03-04,Critical current destabilizing perpendicular magnetization by the spin Hall effect,"The critical current needed to destabilize the magnetization of a
perpendicular ferromagnet via the spin Hall effect is studied. Both the
dampinglike and fieldlike torques associated with the spin current generated by
the spin Hall effect is included in the Landau-Lifshitz-Gilbert equation to
model the system. In the absence of the fieldlike torque, the critical current
is independent of the damping constant and is much larger than that of
conventional spin torque switching of collinear magnetic systems, as in
magnetic tunnel junctions. With the fieldlike torque included, we find that the
critical current scales with the damping constant as $\alpha^{0}$ (i.e.,
damping independent),$\alpha$, and $\alpha^{1/2}$ depending on the sign of the
fieldlike torque and other parameters such as the external field. Numerical and
analytical results show that the critical current can be significantly reduced
when the fieldlike torque possesses the appropriate sign, i.e. when the
effective field associated with the fieldlike torque is pointing opposite to
the spin direction of the incoming electrons. These results provide a pathway
to reducing the current needed to switch magnetization using the spin Hall
effect.",1503.01478v2
2015-03-08,MHD Seismology of a loop-like filament tube by observed kink waves,"We report and analyze the observational evidence of global kink oscillations
in a solar filament as observed in H alpha by National Solar Observatory
(NSO)/Global Oscillation Network Group (GONG) instrument. An M1.1-class flare
in active region 11692 on 2013 March 15 induced a global kink mode in the
filament lying in the south-west of AR11692.We find periods of about 61 - 67
minutes and damping times of 92 - 117 minutes at three vertical slice positions
chosen in and around the filament apex. We find that the waves are damped. From
the observed global kink mode period and damping time scale using the theory of
resonant absorption we perform prominence seismology. We estimate a lower
cut-off value for the inhomogeneity length-scale to be around 0.34 - 0.44 times
the radius of the filament cross-section.",1503.02281v1
2015-03-13,Comparison of spin-orbit torques and spin pumping across NiFe/Pt and NiFe/Cu/Pt interfaces,"We experimentally investigate spin-orbit torques and spin pumping in NiFe/Pt
bilayers with direct and interrupted interfaces. The damping-like and
field-like torques are simultaneously measured with spin-torque ferromagnetic
resonance tuned by a dc bias current, whereas spin pumping is measured
electrically through the inverse spin Hall effect using a microwave cavity.
Insertion of an atomically thin Cu dusting layer at the interface reduces the
damping-like torque, field-like torque, and spin pumping by nearly the same
factor of ~1.4. This finding confirms that the observed spin-orbit torques
predominantly arise from diffusive transport of spin current generated by the
spin Hall effect. We also find that spin-current scattering at the NiFe/Pt
interface contributes to additional enhancement in magnetization damping that
is distinct from spin pumping.",1503.04104v3
2015-03-24,Global weak solutions to compressible quantum Navier-Stokes equations with damping,"The global-in-time existence of weak solutions to the barotropic compressible
quantum Navier-Stokes equations with damping is proved for large data in three
dimensional space. The model consists of the compressible Navier-Stokes
equations with degenerate viscosity, and a nonlinear third-order differential
operator, with the quantum Bohm potential, and the damping terms. The global
weak solutions to such system is shown by using the Faedo-Galerkin method and
the compactness argument. This system is also a very important approximated
system to the compressible Navier-Stokes equations. It will help us to prove
the existence of global weak solutions to the compressible Navier-Stokes
equations with degenerate viscosity in three dimensional space.",1503.06894v4
2015-03-30,Suppression of Spin Pumping Between Ni$_{80}$Fe$_{20}$ and Cu by a Graphene Interlayer,"We compare ferromagnetic resonance measurements of Permalloy
Ni$_{80}$Fe$_{20}$ (Py) films sputtered onto Cu(111) films with and without a
graphene (Gr) interlayer grown by chemical vapor deposition before Py
deposition. A two-angle sputtering method ensured that neither Gr nor Py was
degraded by the sample preparation process. We find the expected damping
enhancement from spin pumping for the Py/Cu case and no detectable enhancement
for the Py/Gr/Cu case. Since damping is sensitive to effects other than spin
pumping, we used magnetometry to verify that differences in Py magnetostatic
properties are not responsible for the difference in damping. We attribute the
suppression of spin pumping in Py/Gr/Cu to the large contact resistance of the
Gr/Cu interface.",1503.08777v1
2015-04-02,Protecting the $\sqrt{SWAP}$ operation from general and residual errors by continuous dynamical decoupling,"We study the occurrence of errors in a continuously decoupled two-qubit state
during a $\sqrt{SWAP}$ quantum operation under decoherence. We consider a
realization of this quantum gate based on the Heisenberg exchange interaction,
which alone suffices for achieving universal quantum computation. Furthermore,
we introduce a continuous-dynamical-decoupling scheme that commutes with the
Heisenberg Hamiltonian to protect it from the amplitude damping and dephasing
errors caused by the system-environment interaction. We consider two
error-protection settings. One protects the qubits from both amplitude damping
and dephasing errors. The other features the amplitude damping as a residual
error and protects the qubits from dephasing errors only. In both settings, we
investigate the interaction of qubits with common and independent environments
separately. We study how errors affect the entanglement and fidelity for
different environmental spectral densities.",1504.00592v1
2015-04-07,Damped Oscillating Dark Energy: Ideal Fluid and Scalar-Tensor description,"In this paper, we study damped oscillating form of dark energy for explaining
dynamics of universe. First of all, we consider universe is filled with an
ideal fluid which has damped oscillating dark energy in terms of this case we
calculate several physical quantities such as Hubble parameter, acceleration
parameter, energy density, pressure and others for dark energy, dark
energy-matter coupling and non-coupling cases. Secondly, we consider as
universe is filled with scalar field instead of an ideal fluid we obtain these
physical quantities in terms of scalar potential and kinetic term for the same
cases in scalar-tensor formalism. Finally, we show that ideal fluid description
and scalar-tensor description of dark energy give mathematically equivalent
results for this EoS parameter, even if they haven't same physical meaning.",1504.01509v2
2015-04-09,"Periodic-coefficient damping estimates, and stability of large-amplitude roll waves in inclined thin film flow","A technical obstruction preventing the conclusion of nonlinear stability of
large-Froude number roll waves of the St. Venant equations for inclined thin
film flow is the ""slope condition"" of Johnson-Noble-Zumbrun, used to obtain
pointwise symmetrizability of the linearized equations and thereby
high-frequency resolvent bounds and a crucial H s nonlinear damping estimate.
Numerically, this condition is seen to hold for Froude numbers 2 \textless{} F
3.5, but to fail for 3.5 F. As hydraulic engineering applications typically
involve Froude number 3 F 5, this issue is indeed relevant to practical
considerations. Here, we show that the pointwise slope condition can be
replaced by an averaged version which holds always, thereby completing the
nonlinear theory in the large-F case. The analysis has potentially larger
interest as an extension to the periodic case of a type of weighted
""Kawashima-type"" damping estimate introduced in the asymptotically-constant
coefficient case for the study of stability of large-amplitude viscous shock
waves.",1504.02292v1
2015-04-17,Temperature-dependent Plasmons and Their Damping Rates for Graphene with a Finite Energy Bandgap,"We obtained numerical and closed-form analytic expressions for
finite-temperature plasmon dispersion relations for intrinsic graphene in the
presence of a finite energy gap in the energy spectrum. The calculations were
carried out using the random-phase approximation. The analytic results have
been derived in the high temperature regime and long-wavelength limit. We have
found that the plasmon damping rate decreases in the presence of a band gap.
Our method of calculation could also be applied to silicene and other buckled
honeycomb lattice structures. The finite-temperature plasmon dispersion
relations are presented when a single graphene layer is Coulomb coupled to a
semi infinite conductor. Both cases of gapless and gapped monolayer graphene
have been investigated when a thick substrate is in their proximity. Both the
plasmon excitation frequency and damping rate are linear functions of the
in-plane wave vector in the long wavelength limit when a monolayer interacts
with a conducting substrate which is not the case for free-standing pristine or
gapped graphene.",1504.04552v1
2015-05-08,Existence and general stabilization of the Timoshenko system with a thermo-viscoelastic damping and a delay term in the internal feedback,"In this paper, we consider a Timoshenko system with a thermo-viscoelastic
damping and a delay term in the internal feedback together with initial datum
and boundary conditions of Dirichlet type, where g is a positive non-increasing
relaxation function and {\mu}1, {\mu}2 are positive constants. Under an
hypothesis between the weight of the delay term in the feedback and the the
weight of the friction damping term, using the Faedo-Galerkin approximations
together with some energy estimates, we prove the global existence of the
solutions. Then, by introducing appropriate Lyapunov functionals, under the
imposed constrain on the weights of the two feedbacks and the coefficients, we
establish the general energy decay result from which the exponential and
polynomial types of decay are only special cases.",1505.01899v1
2015-05-09,"Existence, general decay and blow-up of solutions for a viscoelastic Kirchhoff equation with Balakrishnan-Taylor damping and dynamic boundary conditions","Our aim in this article is to study a nonlinear viscoelastic Kirchhoff
equation with strong damping, Balakrishnan-Taylor damping, nonlinear source and
dynamical boundary condition. Firstly, we prove the local existence of
solutions by using the Faedo-Galerkin approximation method combined with a
contraction mapping theorem. We then prove that if the initial data enter into
the stable set, the solution globally exists, and if the initial data enter
into the unstable set, the solution blows up in a finite time. Moreover, we
obtain a general decay result of the energy, from which the usual exponential
and polynomial decay rates are only special cases.",1505.02220v3
2015-06-03,Migration of two massive planets into (and out of) first order mean motion resonances,"We consider the dynamical evolution of two planets orbiting in the vicinity
of a first order mean motion reso- nance while simultaneously undergoing
eccentricity damping and convergent migration. Following Goldreich &
Schlichting (2014), we include a coupling between the dissipative semimajor
axis evolution and the damping of the eccentricities. In agreement with past
studies, we find that this coupling can lead to overstability of the resonance
and that for a certain range of parameters capture into resonance is only
temporary. Using a more general model, we show that whether overstable motion
can occur depends in a characteristic way on the mass ratio between the two
planets as well as their relative eccentricity damping timescales. Moreover, we
show that even when escape from resonance does occur, the timescale for escape
is long enough such at any given time a pair of planets is more likely to be
found in a resonance rather than migrating between them. Thus, we argue that
overstability of resonances cannot singlehandedly reconcile convergent
migration with the observed lack of Kepler planet pairs found near resonances.
However, it is possible that overstable motion in combination with other
effects such as large scale orbital instability could produce the observed
period ratio distribution.",1506.01382v1
2015-06-12,"Linear inviscid damping for monotone shear flows in a finite periodic channel, boundary effects, blow-up and critical Sobolev regularity","In a previous article, \cite{Zill3}, we have established linear inviscid
damping for a large class of monotone shear flows in a finite periodic channel
and have further shown that boundary effects asymptotically lead to the
formation of singularities of derivatives of the solution. As the main results
of this article, we provide a detailed description of the singularity formation
and establish stability in all sub-critical fractional Sobolev spaces and
blow-up in all super-critical spaces. Furthermore, we discuss the implications
of the blow-up to the problem of nonlinear inviscid damping in a finite
periodic channel, where high regularity would be essential to control nonlinear
effects.",1506.04010v1
2015-06-12,Nonlinear damped partial differential equations and their uniform discretizations,"We establish sharp energy decay rates for a large class of nonlinearly
first-order damped systems, and we design discretization schemes that inherit
of the same energy decay rates, uniformly with respect to the space and/or time
discretization parameters, by adding appropriate numerical viscosity terms. Our
main arguments use the optimal-weight convexity method and uniform
observability inequalities with respect to the discretization parameters. We
establish our results, first in the continuous setting, then for space
semi-discrete models, and then for time semi-discrete models. The full
discretization is inferred from the previous results. Our results cover, for
instance, the Schr\""odinger equation with nonlinear damping, the nonlinear wave
equation, the nonlinear plate equation, as well as certain classes of equations
with nonlocal terms.",1506.04163v2
2015-06-17,Landau Damping of Electrostatic Waves in Arbitrarily Degenerate Quantum Plasmas,"We carry out a systematic study of the dispersion relation for linear
electrostatic waves in an arbitrarily degenerate quantum electron plasma. We
solve for the complex frequency spectrum for arbitrary values of wavenumber $k$
and level of degeneracy $\mu$. Our finding is that for large $k$ and high $\mu$
the real part of the frequency $\omega_{r}$ grows linearly with $k$ and scales
with $\mu$ only because of the scaling of the Fermi energy. In this regime the
relative Landau damping rate $\gamma/\omega_{r}$ becomes independent of $k$ and
varies inversly with $\mu$. Thus, damping is weak but finite at moderate levels
of degeneracy for short wavelengths.",1506.05494v2
2015-06-25,Simultaneous Interconnection and Damping Assignment Passivity-based Control of Mechanical Systems Using Generalized Forces,"To extend the realm of application of the well known controller design
technique of interconnection and damping assignment passivity-based control
(IDA-PBC) of mechanical systems two modifications to the standard method are
presented in this article. First, similarly to [1], it is proposed to avoid the
splitting of the control action into energy-shaping and damping injection
terms, but instead to carry them out simultaneously. Second, motivated by [2],
we propose to consider the inclusion of generalised forces, going beyond the
gyroscopic ones used in standard IDA-PBC. It is shown that several new
controllers for mechanical systems designed invoking other (less systematic
procedures) that do not satisfy the conditions of standard IDA-PBC, actually
belong to this new class of SIDA-PBC.",1506.07679v1
2015-07-20,Bifurcation of the quasinormal spectrum and Zero Damped Modes for rotating dilatonic black holes,"It has been recently found that for the near extremal Kerr black holes
appearing of Zero Damped Modes (accompanied by qusinormal mode branching)
signifies about inapplicability of the regime of small perturbations and the
onset of turbulence. Here we show that this phenomena is not limited by Kerr or
Kerr-Newman solutions only, but also takes place for rotating dilatonic black
holes for which we have found Zero Damped Modes both numerically and
analytically. We have also shown that, contrary to recent claims, there is no
instability of a charged massive scalar field in the background of the rotating
dilatonic black hole under physically adequate boundary conditions. Analytic
expression for dominant quasinormal frequencies is deduced in the regime of
large coupling qQ, where q and Q are the field and black hole charges
respectively.",1507.05649v1
2015-07-24,Effect of Landau damping on alternative ion-acoustic solitary waves in a magnetized plasma consisting of warm adiabatic ions and non-thermal electrons,"Bandyopadhyay and Das [Phys. Plasmas, 9, 465-473, 2002] have derived a
nonlinear macroscopic evolution equation for ion acoustic wave in a magnetized
plasma consisting of warm adiabatic ions and non-thermal electrons including
the effect of Landau damping. In that paper they have also derived the
corresponding nonlinear evolution equation when coefficient of the nonlinear
term of the above mentioned macroscopic evolution equation vanishes, the
nonlinear behaviour of the ion acoustic wave is described by a modified
macroscopic evolution equation. But they have not considered the case when the
coefficient is very near to zero. This is the case we consider in this paper
and we derive the corresponding evolution equation including the effect of
Landau damping. Finally, a solitary wave solution of this macroscopic evolution
is obtained, whose amplitude is found to decay slowly with time.",1507.06733v1
2015-08-05,Quantum discord protection from amplitude damping decoherence,"Entanglement is known to be an essential resource for many quantum
information processes. However, it is now known that some quantum features may
be acheived with quantum discord, a generalized measure of quantum correlation.
In this paper, we study how quantum discord, or more specifically, the measures
of entropic discord and geometric discord are affected by the influence of
amplitude damping decoherence. We also show that a protocol deploying weak
measurement and quantum measurement reversal can effectively protect quantum
discord from amplitude damping decoherence, enabling to distribute quantum
correlation between two remote parties in a noisy environment.",1508.00972v1
2015-09-03,Stability analysis of degenerately-damped oscillations,"Presented here is a study of well-posedness and asymptotic stability of a
""degenerately damped"" PDE modeling a vibrating elastic string. The coefficient
of the damping may vanish at small amplitudes thus weakening the effect of the
dissipation. It is shown that the resulting dynamical system has strictly
monotonically decreasing energy and uniformly decaying lower-order norms,
however, is not uniformly stable on the associated finite-energy space. These
theoretical findings were motivated by numerical simulations of this model
using a finite element scheme and successive approximations. A description of
the numerical approach and sample plots of energy decay are supplied. In
addition, for certain initial data the solution can be determined in closed
form up to a dissipative nonlinear ordinary differential equation. Such
solutions can be used to assess the accuracy of the numerical examples.",1509.00917v1
2015-09-06,Study of spin dynamics and damping on the magnetic nanowire arrays with various nanowire widths,"We investigate the spin dynamics including Gilbert damping in the
ferromagnetic nanowire arrays. We have measured the ferromagnetic resonance of
ferromagnetic nanowire arrays using vector-network analyzer ferromagnetic
resonance (VNA-FMR) and analyzed the results with the micromagnetic
simulations. We find excellent agreement between the experimental VNA-FMR
spectra and micromagnetic simulations result for various applied magnetic
fields. We find that the demagnetization factor for longitudinal conditions, Nz
(Ny) increases (decreases) as decreasing the nanowire width in the
micromagnetic simulations. For the transverse magnetic field, Nz (Ny) increases
(decreases) as increasing the nanowire width. We also find that the Gilbert
damping constant increases from 0.018 to 0.051 as the increasing nanowire width
for the transverse case, while it is almost constant as 0.021 for the
longitudinal case.",1509.01807v1
2015-09-27,On the well-posedness and asymptotic behavior of the generalized KdV-Burgers equation,"In this paper we are concerned with the well-posedness and the exponential
stabilization of the generalized Korteweg-de Vries Burgers equation, posed on
the whole real line, under the effect of a damping term. Both problems are
investigated when the exponent p in the nonlinear term ranges over the interval
$[1,5)$. We first prove the global well-posedness in $H^s(R)$, for $0 \leq s
\leq 3$ and $1 \leq p < 2$, and in $H^3(R)$, when $p \geq 2$. For $2 \leq p <
5$, we prove the existence of global solutions in the $L^2$-setting. Then, by
using multiplier techniques combined with interpolation theory, the exponential
stabilization is obtained for a indefinite damping term and $1 \leq p < 2$.
Under the effect of a localized damping term the result is obtained when $2
\leq p < 5$. Combining multiplier techniques and compactness arguments it is
shown that the problem of exponential decay is reduced to prove the unique
continuation property of weak solutions",1509.08148v1
2015-10-11,Error estimates of finite element method for semi-linear stochastic strongly damped wave equation,"In this paper, we consider a semi-linear stochastic strongly damped wave
equation driven by additive Gaussian noise. Following a semigroup framework, we
establish existence, uniqueness and space-time regularity of a mild solution to
such equation. Unlike the usual stochastic wave equation without damping, the
underlying problem with space-time white noise (Q = I) allows for a mild
solution with a positive order of regularity in multiple spatial dimensions.
Further, we analyze a spatio-temporal discretization of the problem, performed
by a standard finite element method in space and a well-known linear implicit
Euler scheme in time. The analysis of the approximation error forces us to
significantly enrich existing error estimates of semidiscrete and fully
discrete finite element methods for the corresponding linear deterministic
equation. The main results show optimal convergence rates in the sense that the
orders of convergence in space and in time coincide with the orders of the
spatial and temporal regularity of the mild solution, respectively. Numerical
examples are finally included to confirm our theoretical findings.",1510.03028v1
2015-10-13,Nonlocal torque operators in ab initio theory of the Gilbert damping in random ferromagnetic alloys,"We present an ab initio theory of the Gilbert damping in substitutionally
disordered ferromagnetic alloys. The theory rests on introduced nonlocal
torques which replace traditional local torque operators in the well-known
torque-correlation formula and which can be formulated within the atomic-sphere
approximation. The formalism is sketched in a simple tight-binding model and
worked out in detail in the relativistic tight-binding linear muffin-tin
orbital (TB-LMTO) method and the coherent potential approximation (CPA). The
resulting nonlocal torques are represented by nonrandom, non-site-diagonal and
spin-independent matrices, which simplifies the configuration averaging. The
CPA-vertex corrections play a crucial role for the internal consistency of the
theory and for its exact equivalence to other first-principles approaches based
on the random local torques. This equivalence is also illustrated by the
calculated Gilbert damping parameters for binary NiFe and FeCo random alloys,
for pure iron with a model atomic-level disorder, and for stoichiometric FePt
alloys with a varying degree of L10 atomic long-range order.",1510.03571v2
2015-10-23,Laser-induced THz magnetization precession for a tetragonal Heusler-like nearly compensated ferrimagnet,"Laser-induced magnetization precessional dynamics was investigated in
epitaxial films of Mn$_3$Ge, which is a tetragonal Heusler-like nearly
compensated ferrimagnet. The ferromagnetic resonance (FMR) mode was observed,
the precession frequency for which exceeded 0.5 THz and originated from the
large magnetic anisotropy field of approximately 200 kOe for this ferrimagnet.
The effective damping constant was approximately 0.03. The corresponding
effective Landau-Lifshitz constant of approximately 60 Mrad/s and is comparable
to those of the similar Mn-Ga materials. The physical mechanisms for the
Gilbert damping and for the laser-induced excitation of the FMR mode were also
discussed in terms of the spin-orbit-induced damping and the laser-induced
ultrafast modulation of the magnetic anisotropy, respectively.",1510.06793v1
2015-11-10,A study of energy correction for the electron beam data in the BGO ECAL of the DAMPE,"The DArk Matter Particle Explorer (DAMPE) is an orbital experiment aiming at
searching for dark matter indirectly by measuring the spectra of photons,
electrons and positrons originating from deep space. The BGO electromagnetic
calorimeter is one of the key sub-detectors of the DAMPE, which is designed for
high energy measurement with a large dynamic range from 5 GeV to 10 TeV. In
this paper, some methods for energy correction are discussed and tried, in
order to reconstruct the primary energy of the incident electrons. Different
methods are chosen for the appropriate energy ranges. The results of Geant4
simulation and beam test data (at CERN) are presented.",1511.02998v1
2015-11-10,Quantum Fisher and Skew information for Unruh accelerated Dirac qubit,"We develop a Bloch vector representation of Unruh channel for a Dirac field
mode. This is used to provide a unified, analytical treatment of quantum Fisher
and Skew information for a qubit subjected to the Unruh channel, both in its
pure form as well as in the presence of experimentally relevant external noise
channels. The time evolution of Fisher and Skew information is studied along
with the impact of external environment parameters such as temperature and
squeezing. The external noises are modelled by both purely dephasing phase
damping as well as the squeezed generalized amplitude damping channels. An
interesting interplay between the external reservoir temperature and squeezing
on the Fisher and Skew information is observed, in particular, for the action
of the squeezed generalized amplitude damping channel. It is seen that for some
regimes, squeezing can enhance the quantum information against the
deteriorating influence of the ambient environment. Similar features are also
observed for the analogous study of Skew information, highlighting the similar
origin of the Fisher and Skew information.",1511.03029v1
2015-11-23,Detection of high frequency oscillations and damping from multi-slit spectroscopic observations of the corona,"During the total solar eclipse of 11 July 2010, multi-slit spectroscopic
observations of the solar corona were performed from Easter Island, Chile. To
search for high-frequency waves, observations were taken at a high cadence in
the green line at 5303 A due to [Fe xiv] and the red line at 6374 A due to [Fe
x]. The data are analyzed to study the periodic variations in the intensity,
Doppler velocity and line width using wavelet analysis. The data with high
spectral and temporal resolution enabled us to study the rapid dynamical
changes within coronal structures. We find that at certain locations each
parameter shows significant oscillation with periods ranging from 6 - 25 s. For
the first time, we could detect damping of high-frequency oscillations with
periods of the order of 10 s. If the observed damped oscillations are due to
magnetohydrodynamic (MHD) waves then they can contribute significantly in the
heating of the corona. From a statistical study we try to characterize the
nature of the observed oscillations while looking at the distribution of power
in different line parameters.",1511.07160v1
2015-11-26,Uniform exponential stability of Galerkin approximations for damped wave systems,"We consider the numerical approximation of linear damped wave systems by
Galerkin approximations in space and appropriate time-stepping schemes. Based
on a dissipation estimate for a modified energy, we prove exponential decay of
the physical energy on the continuous level provided that the damping is
effective everywhere in the domain. The methods of proof allow us to analyze
also a class of Galerkin approximations based on a mixed variational
formulation of the problem. Uniform exponential stability can be guaranteed for
these approximations under a general compatibility condition on the
discretization spaces. As a particular example, we discuss the discretization
by mixed finite element methods for which we obtain convergence and uniform
error estimates under minimal regularity assumptions. We also prove
unconditional and uniform exponential stability for the time discretization by
certain one-step methods. The validity of the theoretical results as well as
the necessity of some of the conditions required for our analysis are
demonstrated in numerical tests.",1511.08341v1
2016-01-03,Event-triggered Communication in Wide-area Damping Control: A Limited Output Feedback Based Approach,"A conceptual design methodology is proposed for event-triggered based power
system wide area damping controller. The event-triggering mechanism is adopted
to reduce the communication burden between origin of the remote signal and the
wide area damping controller (WADC) location. The remote signal is transmitted
to the WADC only when an event-triggering condition based on a predefined
system output, is satisfied. The triggering condition is derived from a
stability criterion, and is monitored continuously by a separate
event-monitoring unit located at the origin of the remote signal. The stability
of the resulting closed loop system is guaranteed via the input-to-state
stability (ISS) technique. The proposed event triggered WADC (ET-WADC) is
implemented on two typical test power systems - two area four machine and IEEE
39 bus 10 machine. The validation of proposed mechanism is carried out through
non-linear simulation studies on MATLAB/Simulink platform. The numerical
results show the efficacy of the controller in managing the communication
channel usage without compromising the stated system stability objectives.",1601.00255v1
2016-01-05,Lie transformation method on quantum state evolution of a general time-dependent driven and damped parametric oscillator,"A variety of dynamics in nature and society can be approximately treated as a
driven and damped parametric oscillator. An intensive investigation of this
time-dependent model from an algebraic point of view provides a consistent
method to resolve the classical dynamics and the quantum evolution in order to
understand the time-dependent phenomena that occur not only in the macroscopic
classical scale for the synchronized behaviors but also in the microscopic
quantum scale for a coherent state evolution. By using a Floquet
U-transformation on a general time-dependent quadratic Hamiltonian, we exactly
solve the dynamic behaviors of a driven and damped parametric oscillator to
obtain the optimal solutions by means of invariant parameters of $K$s to
combine with Lewis-Riesenfeld invariant method. This approach can discriminate
the external dynamics from the internal evolution of a wave packet by producing
independent parametric equations that dramatically facilitate the parametric
control on the quantum state evolution in a dissipative system. In order to
show the advantages of this method, several time-dependent models proposed in
the quantum control field are analyzed in details.",1601.00727v3
2016-02-19,Distinctive response of many-body localized systems to strong electric field,"We study systems which are close to or within the many-body localized (MBL)
regime and are driven by strong electric field. In the ergodic regime, the
disorder extends applicability of the equilibrium linear--response theory to
stronger drivings, whereas the response of the MBL systems is very distinctive,
revealing currents with damped oscillations. The oscillation frequency is
independent of driving and the damping is not due to heating but rather due to
dephasing. The details of damping depend on the system's history reflecting
nonergodicity of the MBL phase, while the frequency of the oscillations remains
a robust hallmark of localization. We show that the distinctive characteristic
of the driven MBL phase is also a logarithmic increase of the energy and the
polarization with time.",1602.06055v1
2016-02-24,Pressure of a gas of underdamped active dumbbells,"The pressure exerted on a wall by a gas at equilibrium does not depend on the
shape of the confining potential defining the wall. In contrast, it has been
shown recently [A.P. Solon et al., Nat. Phys. 11, 673 (2015)] that a gas of
overdamped active particles exerts on a wall a force that depends on the
confining potential, resulting in a net force on an asymmetric wall between two
chambers at equal densities. Here, considering a model of underdamped
self-propelled dumbbells in two dimensions, we study how the behavior of the
pressure depends on the damping coefficient of the dumbbells, thus exploring
inertial effects. We find in particular that the force exerted on a moving wall
between two chambers at equal density continuously vanishes at low damping
coefficient, and exhibits a complex dependence on the damping coefficient at
low density, when collisions are scarce. We further show that this behavior of
the pressure can to a significant extent be understood in terms of the
trajectories of individual particles close to and in contact with the wall.",1602.07420v1
2016-03-07,Optimal Load and Stiffness for Displacement-Constrained Vibration Energy Harvesters,"The power electronic interface to a vibration energy harvester not only
provides ac-dc conversion, but can also set the electrical damping to maximize
output power under displacement-constrained operation. This is commonly
exploited for linear two-port harvesters by synchronous switching to realize a
Coulomb-damped resonant generator, but has not been fully explored when the
harvester is asynchronously switched to emulate a resistive load. In order to
understand the potential of such an approach, the optimal values of load
resistance and other control parameters need to be known. In this paper we
determine analytically the optimal load and stiffness of a harmonically driven
two-port harvester with displacement constraints. For weak-coupling devices, we
do not find any benefit of load and stiffness adjustment beyond maintaining a
saturated power level. For strong coupling we find that the power can be
optimized to agree with the velocity damped generator beyond the first critical
force for displacement-constrained operation. This can be sustained up to a
second critical force, determined by a resonator figure-of-merit, at which the
power ultimately levels out.",1603.01909v1
2016-03-22,Generation and protection of steady-state quantum correlations due to quantum channels with memory,"We have proposed a scheme of the generation and preservation of two-qubit
steady state quantum correlations through quantum channels where successive
uses of the channels are correlated. Different types of noisy channels with
memory, such as amplitude damping, phase-damping, and depolarizing channels
have been taken into account. Some analytical or numerical results are
presented. The effect of channels with memory on dynamics of quantum
correlations has been discussed in detail. The results show that, steady state
entanglement between two independent qubits without entanglement subject to
amplitude damping channel with memory can be generated. Besides, we compare the
dynamics of entanglement with that of quantum discord when a two-qubit system
is prepared in an entangled state. We show that entanglement dynamics suddenly
disappears, while quantum discord displays only in the asymptotic limit.
Two-qubit quantum correlations can be preserved at a long time in the limit of
$\mu\rightarrow1$.",1603.06676v2
2016-03-25,Large spin pumping effect in antisymmetric precession of Ni$_{79}$Fe$_{21}$/Ru/Ni$_{79}$Fe$_{21}$,"In magnetic trilayer structures, a contribution to the Gilbert damping of
ferromagnetic resonance arises from spin currents pumped from one layer to
another. This contribution has been demonstrated for layers with weakly
coupled, separated resonances, where magnetization dynamics are excited
predominantly in one layer and the other layer acts as a spin sink. Here we
show that trilayer structures in which magnetizations are excited
simultaneously, antisymmetrically, show a spin-pumping effect roughly twice as
large. The antisymmetric (optical) mode of antiferromagnetically coupled
Ni$_{79}$Fe$_{21}$(8nm)/Ru/Ni$_{79}$Fe$_{21}$(8nm) trilayers shows a Gilbert
damping constant greater than that of the symmetric (acoustic) mode by an
amount as large as the intrinsic damping of Py ($\Delta
\alpha\simeq\textrm{0.006}$). The effect is shown equally in field-normal and
field-parallel to film plane geometries over 3-25 GHz. The results confirm a
prediction of the spin pumping model and have implications for the use of
synthetic antiferromagnets (SAF)-structures in GHz devices.",1603.07977v1
2016-03-31,Recovery of time-dependent damping coefficients and potentials appearing in wave equations from partial data,"We consider the inverse problem of determining a time-dependent damping
coefficient $a$ and a time-dependent potential $q$, appearing in the wave
equation $\partial_t^2u-\Delta_x u+a(t,x)\partial_tu+q(t,x)u=0$ in
$Q=(0,T)\times\Omega$, with $T>0$ and $\Omega$ a $ \mathcal C^2$ bounded domain
of $\mathbb R^n$, $n\geq2$, from partial observations of the solutions on
$\partial Q$. More precisely, we look for observations on $\partial Q$ that
allow to determine uniquely a large class of time-dependent damping
coefficients $a$ and time-dependent potentials $q$ without involving an
important set of data. We prove global unique determination of $a\in
W^{1,p}(Q)$, with $p>n+1$, and $q\in L^\infty(Q)$ from partial observations on
$\partial Q$.",1603.09600v2
2016-04-22,Feedback-induced Bistability of an Optically Levitated Nanoparticle: A Fokker-Planck Treatment,"Optically levitated nanoparticles have recently emerged as versatile
platforms for investigating macroscopic quantum mechanics and enabling
ultrasensitive metrology. In this article we theoretically consider two damping
regimes of an optically levitated nanoparticle cooled by cavityless parametric
feedback. Our treatment is based on a generalized Fokker-Planck equation
derived from the quantum master equation presented recently and shown to agree
very well with experiment [1]. For low damping, we find that the resulting
Wigner function yields the single-peaked oscillator position distribution and
recovers the appropriate energy distribution derived earlier using a classical
theory and verified experimentally [2]. For high damping, in contrast, we
predict a double-peaked position distribution, which we trace to an underlying
bistability induced by feedback. Unlike in cavity-based optomechanics,
stochastic processes play a major role in determining the bistable behavior. To
support our conclusions, we present analytical expressions as well as numerical
simulations using the truncated Wigner function approach. Our work opens up the
prospect of developing bistability-based devices, characterization of
phase-space dynamics, and investigation of the quantum-classical transition
using levitated nanoparticles.",1604.06767v2
2016-06-08,Effect of quantum noise on deterministic joint remote state preparation of a qubit state via a GHZ channel,"Quantum secure communication brings a new direction for information security.
As an important component of quantum secure communication, deterministic joint
remote state preparation (DJRSP) could securely transmit a quantum state with
100\% success probability. In this paper, we study how the efficiency of DJRSP
is affected when qubits involved in the protocol are subjected to noise or
decoherence. Taking a GHZ based DJRSP scheme as an example, we study all types
of noise usually encountered in real-world implementations of quantum
communication protocols, i.e., the bit-flip, phase-flip (phase-damping),
depolarizing, and amplitude-damping noise. Our study shows that the fidelity of
the output state depends on the phase factor, the amplitude factor and the
noise parameter in the bit-flip noise, while the fidelity only depends on the
amplitude factor and the noise parameter in the other three types of noise. And
the receiver will get different output states depending on the first preparer's
measurement result in the amplitude-damping noise. Our results will be helpful
for improving quantum secure communication in real implementation.",1606.02484v2
2016-06-28,Radiation Damping by Thomson Scattering,"Synchrotron radiation of relativistic electrons in storage rings naturally
leads to the process of damping of betatron oscillations. Damping time and
transverse beam emittance can be reduced by wigglers or undulators while the
beam parameters are still well defined by the common radiation integrals, based
on the properties of synchrotron radiation. However, the quantum excitation of
betatron oscillations in principle can be considerably reduced if an electron
radiation occurs due to the Thomson scattering in the periodic electromagnetic
field. After a brief introduction we compare radiation properties for different
cases and suggest the modification of the radiation integrals.",1606.08602v5
2016-06-29,"Kinodynamic Motion Planning: A Novel Type Of Nonlinear, Passive Damping Forces And Advantages","This article extends the capabilities of the harmonic potential field
approach to planning to cover both the kinematic and dynamic aspects of a robot
motion. The suggested approach converts the gradient guidance field from a
harmonic potential to a control signal by augmenting it with a novel type of
damping forces called nonlinear, anisotropic, damping forces. The combination
of the two provides a signal that can both guide a robot and effectively manage
its dynamics. The kinodynamic planning signal inherits the guidance
capabilities of the harmonic gradient field. It can also be easily configured
to efficiently suppress the inertia-induced transients in the robot trajectory
without compromising the speed of operation. The approach works with
dissipative systems as well as systems acted on by external forces without
needing the full knowledge of the system dynamics. Theoretical developments and
simulation results are provided in this article.",1606.09270v1
2016-07-18,Magnetic Skyrmion Transport in a Nanotrack With Spatially Varying Damping and Non-adiabatic Torque,"Reliable transport of magnetic skyrmions is required for any future
skyrmion-based information processing devices. Here we present a micromagnetic
study of the in-plane current-driven motion of a skyrmion in a ferromagnetic
nanotrack with spatially sinusoidally varying Gilbert damping and/or
non-adiabatic spin-transfer torque coefficients. It is found that the skyrmion
moves in a sinusoidal pattern as a result of the spatially varying Gilbert
damping and/or non-adiabatic spin-transfer torque in the nanotrack, which could
prevent the destruction of the skyrmion caused by the skyrmion Hall effect. The
results provide a guide for designing and developing the skyrmion transport
channel in skyrmion-based spintronic applications.",1607.04983v3
2016-07-20,"Envelope equation for the linear and nonlinear propagation of an electron plasma wave, including the effects of Landau damping, trapping, plasma inhomogeneity, and the change in the state of wave","This paper addresses the linear and nonlinear three-dimensional propagation
of an electron wave in a collisionless plasma that may be inhomogeneous,
nonstationary, anisotropic and even weakly magnetized. The wave amplitude,
together with any hydrodynamic quantity characterizing the plasma (density,
temperature,...) are supposed to vary very little within one wavelength or one
wave period. Hence, the geometrical optics limit is assumed, and the wave
propagation is described by a first order differential equation. This equation
explicitly accounts for three-dimensional effects, plasma inhomogeneity, Landau
damping, and the collisionless dissipation and electron acceleration due to
trapping. It is derived by mixing results obtained from a direct resolution of
the Vlasov-Poisson system and from a variational formalism involving a nonlocal
Lagrangian density. In a one-dimensional situation, abrupt transitions are
predicted in the coefficients of the wave equation. They occur when the state
of the electron plasma wave changes, from a linear wave to a wave with trapped
electrons. In a three dimensional geometry, the transitions are smoother,
especially as regards the nonlinear Landau damping rate, for which a very
simple effective and accurate analytic expression is provided.",1607.05844v2
2016-09-02,Particle dynamics and Stochastic Resonance in Periodic potentials,"We have studied the dynamics of a particle in a periodically driven
underdamped periodic potential. Recent studies have reported the occurrence of
Stochastic Resonance (SR) in such systems in the high frequency regime, using
input energy per period of external drive as a quantifier. The particle
trajectories in these systems can be in two dynamical states characterised by
their definite energy and phase relation with the external drive. SR is due to
the noise assisted transition of the particles between these two states. We
study the role of damping on the occurrence of SR. We show that a driven
underdamped periodic system exhibits SR only if the damping is below a
particular limit. To explain this we study the syatem in the deterministic
regime. The existence of the two dynamical states in the deterministic regime
is dependent on the amount of damping and the amplitude od external drive. We
also study the input energy distributions and phase difference of the response
amplitude with the external drive as afunction of the friction parameter.",1609.00678v1
2016-09-26,An efficient quantum algorithm for spectral estimation,"We develop an efficient quantum implementation of an important signal
processing algorithm for line spectral estimation: the matrix pencil method,
which determines the frequencies and damping factors of signals consisting of
finite sums of exponentially damped sinusoids. Our algorithm provides a quantum
speedup in a natural regime where the sampling rate is much higher than the
number of sinusoid components. Along the way, we develop techniques that are
expected to be useful for other quantum algorithms as well - consecutive phase
estimations to efficiently make products of asymmetric low rank matrices
classically accessible and an alternative method to efficiently exponentiate
non-Hermitian matrices. Our algorithm features an efficient quantum-classical
division of labor: The time-critical steps are implemented in quantum
superposition, while an interjacent step, requiring only exponentially few
parameters, can operate classically. We show that frequencies and damping
factors can be obtained in time logarithmic in the number of sampling points,
exponentially faster than known classical algorithms.",1609.08170v1
2016-10-01,On the regularization of impact without collision: the Painlevé paradox and compliance,"We consider the problem of a rigid body, subject to a unilateral constraint,
in the presence of Coulomb friction. We regularize the problem by assuming
compliance (with both stiffness and damping) at the point of contact, for a
general class of normal reaction forces. Using a rigorous mathematical
approach, we recover impact without collision (IWC) in both the inconsistent
and indeterminate Painlev\'e paradoxes, in the latter case giving an exact
formula for conditions that separate IWC and lift-off. We solve the problem for
arbitrary values of the compliance damping and give explicit asymptotic
expressions in the limiting cases of small and large damping, all for a large
class of rigid bodies.",1610.00143v2
2016-10-21,Spin transport and dynamics in all-oxide perovskite La$_{2/3}$Sr$_{1/3}$MnO$_3$/SrRuO$_3$ bilayers probed by ferromagnetic resonance,"Thin films of perovskite oxides offer the possibility of combining emerging
concepts of strongly correlated electron phenomena and spin current in magnetic
devices. However, spin transport and magnetization dynamics in these complex
oxide materials are not well understood. Here, we experimentally quantify spin
transport parameters and magnetization damping in epitaxial perovskite
ferromagnet/paramagnet bilayers of La$_{2/3}$Sr$_{1/3}$MnO$_3$/SrRuO$_3$
(LSMO/SRO) by broadband ferromagnetic resonance spectroscopy. From the SRO
thickness dependence of Gilbert damping, we estimate a short spin diffusion
length of $\lesssim$1 nm in SRO and an interfacial spin-mixing conductance
comparable to other ferromagnet/paramagnetic-metal bilayers. Moreover, we find
that anisotropic non-Gilbert damping due to two-magnon scattering also
increases with the addition of SRO. Our results demonstrate LSMO/SRO as a
spin-source/spin-sink system that may be a foundation for examining
spin-current transport in various perovskite heterostructures.",1610.06661v1
2017-02-15,Topological Properties of a Coupled Spin-Photon System Induced by Damping,"We experimentally examine the topological nature of a strongly coupled
spin-photon system induced by damping. The presence of both spin and photonic
losses results in a non-Hermitian system with a variety of exotic phenomena
dictated by the topological structure of the eigenvalue spectra and the
presence of an exceptional point (EP), where the coupled spin-photon
eigenvectors coalesce. By controlling both the spin resonance frequency and the
spin-photon coupling strength we observe a resonance crossing for
cooperativities above one, suggesting that the boundary between weak and strong
coupling should be based on the EP location rather than the cooperativity.
Furthermore we observe dynamic mode switching when encircling the EP and
identify the potential to engineer the topological structure of coupled
spin-photon systems with additional modes. Our work therefore further
highlights the role of damping within the strong coupling regime, and
demonstrates the potential and great flexibility of spin-photon systems for
studies of non-Hermitian physics.",1702.04797v2
2017-02-22,Modified quantum-speed-limit bounds for open quantum dynamics in quantum channels,"The minimal evolution time between two distinguishable states is of
fundamental interest in quantum physics. Very recently Mirkin et al. argue that
some most common quantum-speed-limit (QSL) bounds which depend on the actual
evolution time do not cleave to the essence of the QSL theory as they grow
indefinitely but the final state is reached at a finite time in a damped
Jaynes-Cummings (JC) model. In this paper, we thoroughly study this puzzling
phenomenon. We find the inconsistent estimates will happen if and only if the
limit of resolution of a calculation program is achieved, through which we
propose that the nature of the inconsistency is not a violation to the essence
of the QSL theory but an illusion caused by the finite precision in numerical
simulations. We also present a generic method to overcome the inconsistent
estimates and confirm its effectiveness in both amplitude-damping and
phase-damping channels. Additionally, we show special cases which may restrict
the QSL bound defined by ""quantumness"".",1702.06748v3
2017-03-07,Lower Bound and optimality for a nonlinearly damped Timoshenko system with thermoelasticity,"In this paper, we consider a vibrating nonlinear Timoshenko system with
thermoelasticity with second sound. We first investigate the strong stability
of this system, then we devote our efforts to obtain the strong lower energy
estimates using Alabau--Boussouira's energy comparison principle introduced in
\cite{2} (see also \cite{alabau}). One of the main advantages of these results
is that they allows us to prove the optimality of the asymptotic results (as
$t\rightarrow \infty$) obtained in \cite{ali}. We also extend to our model the
nice results achieved in \cite{alabau} for the case of nonlinearly damped
Timoshenko system with thermoelasticity. The optimality of our results is also
investigated through some explicit examples of the nonlinear damping term. The
proof of our results relies on the approach in \cite{AB1, AB2}.",1703.02599v4
2017-03-08,A Parameterized Energy Correction Method for Electromagnetic Showers in BGO-ECAL of DAMPE,"DAMPE is a space-based mission designed as a high energy particle detector
measuring cosmic-rays and $\gamma-$rays which was successfully launched on
Dec.17, 2015. The BGO electromagnetic calorimeter is one of the key
sub-detectors of DAMPE for energy measurement of electromagnetic showers
produced by $e^{\pm}/{\gamma}$. Due to energy loss in dead material and energy
leakage outside the calorimeter, the deposited energy in BGO underestimates the
primary energy of incident $e^{\pm}/{\gamma}$. In this paper, based on detailed
MC simulations, a parameterized energy correction method using the lateral and
longitudinal information of electromagnetic showers has been studied and
verified with data of electron beam test at CERN. The measurements of energy
linearity and resolution are significantly improved by applying this correction
method for electromagnetic showers.",1703.02821v2
2017-03-08,A GAMP Based Low Complexity Sparse Bayesian Learning Algorithm,"In this paper, we present an algorithm for the sparse signal recovery problem
that incorporates damped Gaussian generalized approximate message passing
(GGAMP) into Expectation-Maximization (EM)-based sparse Bayesian learning
(SBL). In particular, GGAMP is used to implement the E-step in SBL in place of
matrix inversion, leveraging the fact that GGAMP is guaranteed to converge with
appropriate damping. The resulting GGAMP-SBL algorithm is much more robust to
arbitrary measurement matrix $\boldsymbol{A}$ than the standard damped GAMP
algorithm while being much lower complexity than the standard SBL algorithm. We
then extend the approach from the single measurement vector (SMV) case to the
temporally correlated multiple measurement vector (MMV) case, leading to the
GGAMP-TSBL algorithm. We verify the robustness and computational advantages of
the proposed algorithms through numerical experiments.",1703.03044v2
2017-03-28,Singularity formation for the 1D compressible Euler equation with variable damping coefficient,"In this paper, we consider some blow-up problems for the 1D Euler equation
with time and space dependent damping. We investigate sufficient conditions on
initial data and the rate of spatial or time-like decay of the coefficient of
damping for the occurrence of the finite time blow-up. In particular, our
sufficient conditions ensure that the derivative blow-up occurs in finite time
with the solution itself and the pressure bounded. Our method is based on
simple estimates with Riemann invariants. Furthermore, we give sharp lower and
upper estimates of the lifespan of solutions, when initial data are small
perturbations of constant states.",1703.09821v3
2017-08-30,Convergence to diffusion waves for solutions of Euler equations with time-depending damping on quadrant,"This paper is concerned with the asymptotic behavior of the solution to the
Euler equations with time-depending damping on quadrant $(x,t)\in
\mathbb{R}^+\times\mathbb{R}^+$, \begin{equation}\notag \partial_t v
  -
  \partial_x u=0, \qquad \partial_t u
  +
  \partial_x p(v)
  =\displaystyle
  -\frac{\alpha}{(1+t)^\lambda} u, \end{equation} with null-Dirichlet boundary
condition or null-Neumann boundary condition on $u$. We show that the
corresponding initial-boundary value problem admits a unique global smooth
solution which tends time-asymptotically to the nonlinear diffusion wave.
Compared with the previous work about Euler equations with constant coefficient
damping, studied by Nishihara and Yang (1999, J. Differential Equations, 156,
439-458), and Jiang and Zhu (2009, Discrete Contin. Dyn. Syst., 23, 887-918),
we obtain a general result when the initial perturbation belongs to the same
space. In addition, our main novelty lies in the facts that the cut-off points
of the convergence rates are different from our previous result about the
Cauchy problem. Our proof is based on the classical energy method and the
analyses of the nonlinear diffusion wave.",1708.09127v1
2018-02-12,Chance-constrained optimal location of damping control actuators under wind power variability,"This paper proposes a new probabilistic energy-based method to determine the
optimal installation location of electronically-interfaced resources (EIRs)
considering dynamic reinforcement under wind variability in systems with high
penetration of wind power. The oscillation energy and total action are used to
compare the dynamic performance for different EIR locations. A linear
approximation of the total action critically reduces the computational time
from hours to minutes. Simulating an IEEE-39 bus system with 30% of power
generation sourced from wind, a chance-constrained optimization is carried out
to decide the location of an energy storage system (ESS) adding damping to the
system oscillations. The results show that the proposed method, selecting the
bus location that guarantees the best dynamic performance with highest
probability, is superior to both traditional dominant mode analysis and
arbitrary benchmarks for damping ratios.",1802.04354v1
2018-02-21,On the vibron-polaron damping in quasi 1D macromolecular chains,"The properties of the intramolecular vibrational excitation (vibron) in a
quasi 1D macromolecular structure are studied. It is supposed that due to the
vibron interaction with optical phonon modes, a vibron might form partially
dressed small polaron states. The properties of these states are investigated
in dependence on the basic system parameters and temperature of a thermal bath.
We also investigate the process of damping of the polaron amplitude as a
function of temperature and vibron-phonon coupling strength. Two different
regimes of the polaron damping are found and discussed.",1802.07424v1
2018-02-27,Impact of damping on superconducting gap oscillations induced by intense Terahertz pulses,"We investigate the interplay between gap oscillations and damping in the
dynamics of superconductors taken out of equilibrium by strong optical pulses
with sub-gap Terahertz frequencies. A semi-phenomenological formalism is
developed to include the damping within the electronic subsystem that arises
from effects beyond BCS, such as interactions between Bogoliubov quasiparticles
and decay of the Higgs mode. Such processes are conveniently expressed as
$T_{1}$ and $T_{2}$ times in the standard pseudospin language for
superconductors. Comparing with data on NbN that we report here, we argue that
the superconducting dynamics in the picosecond time scale, after the pump is
turned off, is governed by the $T_{2}$ process.",1802.09711v2
2018-02-28,Analysis of imperfections in the coherent optical excitation of single atoms to Rydberg states,"We study experimentally various physical limitations and technical
imperfections that lead to damping and finite contrast of optically-driven Rabi
oscillations between ground and Rydberg states of a single atom. Finite
contrast is due to preparation and detection errors and we show how to model
and measure them accurately. Part of these errors originates from the finite
lifetime of Rydberg states and we observe its $n^3$-scaling with the principal
quantum number $n$. To explain the damping of Rabi oscillations, we use simple
numerical models, taking into account independently measured experimental
imperfections, and show that the observed damping actually results from the
accumulation of several small effects, each at the level of a few percents. We
discuss prospects for improving the coherence of ground-Rydberg Rabi
oscillations in view of applications in quantum simulation and quantum
information processing with arrays of single Rydberg atoms.",1802.10424v1
2018-04-01,Bounded Connectivity-Preserving Coordination of Networked Euler-Lagrange Systems,"This paper derives sufficient conditions for bounded distributed
connectivity-preserving coordination of Euler-Lagrange systems with only
position measurements and with system uncertainties, respectively. The paper
proposes two strategies that suitably scale conventional gradient-based
controls to account for the actuation bounds and to reserve sufficient
actuation for damping injection. For output feedback control of networked
systems with only position measurements, the paper incorporates a first-order
filter to estimate velocities and to inject damping for stability. For networks
of uncertain systems, the paper augments conventional linear filter-based
adaptive compensation with damping injection to maintain the local connectivity
of the network. Analyses based on monotonically decreasing Lyapunov-like
functions and Barbalat's lemma lead to sufficient conditions for bounded local
connectivity-preserving coordination of Euler-Lagrange networks under the two
strategies. The sufficient conditions clarify the interrelationships among the
bounded actuations, initial system velocities and initial inter-system
distances. Simulation results validate these conditions.",1804.00333v1
2018-04-09,Damping and clustering into crowded environment of catalytic chemical oscillators,"A system formed by a crowded environment of catalytic obstacles and complex
oscillatory chemical reactions is inquired. The obstacles are static spheres of
equal radius, which are placed in a random way. The chemical reactions are
carried out in a fluid following a multiparticle collision scheme where the
mass, energy and local momentum are conserved. Firstly, it is explored how the
presence of catalytic obstacles changes the oscillatory dynamics from a limit
cycle to a fix point reached after a damping. The damping is characterized by
the decay constant, which grows linearly with volume fraction for low values of
the mesoscale collision time and the catalytic reaction constant. Additionally,
it is shown that, although the distribution of obstacles is random, there are
regions in the system where the catalytic chemical reactions are favored. This
entails that in average the radius of gyrations of catalytic chemical reaction
does not match with the radius of gyration of obstacles, that is, clusters of
reactions emerge on the catalytic obstacles, even when the diffusion is
significant.",1804.03174v1
2018-04-11,A global existence result for a semilinear wave equation with scale-invariant damping and mass in even space dimension,"In the present article a semilinear wave equation with scale-invariant
damping and mass is considered. The global (in time) existence of radial
symmetric solutions in even spatial dimension $n$ is proved using weighted
$L^\infty-L^\infty$ estimates, under the assumption that the multiplicative
constants, which appear in the coefficients of damping and of mass terms,
fulfill an interplay condition which yields somehow a ""wave-like"" model. In
particular, combining this existence result with a recently proved blow-up
result, a suitable shift of Strauss exponent is proved to be the critical
exponent for the considered model. Moreover, the still open part of a
conjecture done by D'Abbicco - Lucente - Reissig is proved to be true in the
massless case.",1804.03978v1
2018-04-17,Modelling linewidths of Kepler red giants in NGC 6819,"We present a comparison between theoretical, frequency-dependent, damping
rates and linewidths of radial-mode oscillations in red-giant stars located in
the open cluster NGC 6819. The calculations adopt a time-dependent non-local
convection model, with the turbulent pressure profile being calibrated to
results of 3D hydrodynamical simulations of stellar atmospheres. The linewidths
are obtained from extensive peakbagging of Kepler lightcurves. These
observational results are of unprecedented quality owing to the long continuous
observations by Kepler. The uniqueness of the Kepler mission also means that,
for asteroseismic properties, this is the best data that will be available for
a long time to come. We therefore take great care in modelling nine RGB stars
in NGC 6819 using information from 3D simulations to obtain realistic
temperature stratifications and calibrated turbulent pressure profiles. Our
modelled damping rates reproduce well the Kepler observations, including the
characteristic depression in the linewidths around the frequency of maximum
oscillation power. Furthermore, we thoroughly test the sensitivity of the
calculated damping rates to changes in the parameters of the nonlocal
convection model.",1804.06255v1
2018-04-24,$\text{Co}_{25}\text{Fe}_{75}$ Thin Films with Ultralow Total Damping,"We measure the dynamic properties of $\text{Co}_{25}\text{Fe}_{75}$ thin
films grown by dc magnetron sputtering. Using ferromagnetic resonance
spectroscopy, we demonstrate an ultralow total damping parameter in the
out-of-plane configuration of < 0.0013, whereas for the in-plane configuration
we find a minimum total damping of < 0.0020. In both cases, we observe low
inhomogeneous linewidth broadening in macroscopic films. We observe a minimum
full-width half-maximum linewidth of 1 mT at 10 GHz resonance frequency for a
12 nm thick film. We characterize the morphology and structure of these films
as a function of seed layer combinations and find large variation of the
qualitative behavior of the in-plane linewidth vs. resonance frequency.
Finally, we use wavevector-dependent Brillouin light scattering spectroscopy to
characterize the spin-wave dispersion at wave vectors up to 23 $\mu
\text{m}^{-1}$.",1804.08786v1
2018-04-03,Generalisation of Gilbert damping and magnetic inertia parameter as a series of higher-order relativistic terms,"The phenomenological Landau-Lifshitz-Gilbert (LLG) equation of motion remains
as the cornerstone of contemporary magnetisation dynamics studies, wherein the
Gilbert damping parameter has been attributed to first-order relativistic
effects. To include magnetic inertial effects the LLG equation has previously
been extended with a supplemental inertia term and the arising inertial
dynamics has been related to second-order relativistic effects. Here we start
from the relativistic Dirac equation and, performing a Foldy-Wouthuysen
transformation, derive a generalised Pauli spin Hamiltonian that contains
relativistic correction terms to any higher order. Using the Heisenberg
equation of spin motion we derive general relativistic expressions for the
tensorial Gilbert damping and magnetic inertia parameters, and show that these
tensors can be expressed as series of higher-order relativistic correction
terms. We further show that, in the case of a harmonic external driving field,
these series can be summed and we provide closed analytical expressions for the
Gilbert and inertial parameters that are functions of the frequency of the
driving field.",1804.09242v1
2018-10-31,Anisotropic and controllable Gilbert-Bloch dissipation in spin valves,"Spin valves form a key building block in a wide range of spintronic concepts
and devices from magnetoresistive read heads to spin-transfer-torque
oscillators. We elucidate the dependence of the magnetic damping in the free
layer on the angle its equilibrium magnetization makes with that in the fixed
layer. The spin pumping-mediated damping is anisotropic and tensorial, with
Gilbert- and Bloch-like terms. Our investigation reveals a mechanism for tuning
the free layer damping in-situ from negligible to a large value via the
orientation of fixed layer magnetization, especially when the magnets are
electrically insulating. Furthermore, we expect the Bloch contribution that
emerges from the longitudinal spin accumulation in the non-magnetic spacer to
play an important role in a wide range of other phenomena in spin valves.",1811.00020v2
2018-11-06,Decay properties and asymptotic profiles for elastic waves with Kelvin-Voigt damping in 2D,"In this paper we consider elastic waves with Kelvin-Voigt damping in 2D. For
the linear problem, applying pointwise estimates of the partial Fourier
transform of solutions in the Fourier space and asymptotic expansions of
eigenvalues and their eigenprojections, we obtain sharp energy decay estimates
with additional $L^m$ regularity and $L^p-L^q$ estimates on the conjugate line.
Furthermore, we derive asymptotic profiles of solutions under different
assumptions of initial data. For the semilinear problem, we use the derived
$L^2-L^2$ estimates with additional $L^m$ regularity to prove global (in time)
existence of small data solutions to the weakly coupled system. Finally, to
deal with elastic waves with Kelvin-Voigt damping in 3D, we apply the Helmholtz
decomposition.",1811.02223v3
2019-05-08,Discrete Energy behavior of a damped Timoshenko system,"In this article, we consider a one-dimensional Timoshenko system subject to
different types of dissipation (linear and nonlinear dampings). Based on a
combination between the finite element and the finite difference methods, we
design a discretization scheme for the different Timoshenko systems under
consideration. We first come up with a numerical scheme to the free-undamped
Timoshenko system. Then, we adapt this numerical scheme to the corresponding
linear and nonlinear damped systems. Interestingly, this scheme reaches to
reproduce the most important properties of the discrete energy. Namely, we show
for the discrete energy the positivity, the energy conservation property and
the different decay rate profiles. We numerically reproduce the known
analytical results established on the decay rate of the energy associated with
each type of dissipation.",1905.03050v1
2019-05-08,Attractors for semilinear wave equations with localized damping and external forces,"This paper is concerned with long-time dynamics of semilinear wave equations
defined on bounded domains of $\mathbb{R}^3$ with cubic nonlinear terms and
locally distributed damping. The existence of regular finite-dimensional global
attractors established by Chueshov, Lasiecka and Toundykov (2008) reflects a
good deal of the current state of the art on this matter. Our contribution is
threefold. First, we prove uniform boundedness of attractors with respect to a
forcing parameter. Then, we study the continuity of attractors with respect to
the parameter in a residual dense set. Finally, we show the existence of
generalized exponential attractors. These aspects were not previously
considered for wave equations with localized damping.",1905.03285v1
2019-05-16,Global attractors and their upper semicontinuity for a structural damped wave equation with supercritical nonlinearity on $\mathbb{R}^{N}$,"The paper investigates the existence of global attractors and their upper
semicontinuity for a structural damped wave equation on $\mathbb{R}^{N}:
u_{tt}-\Delta u+(-\Delta)^\alpha u_{t}+u_{t}+u+g(u)=f(x)$, where $\alpha\in
(1/2, 1)$ is called a dissipative index. We propose a new method based on the
harmonic analysis technique and the commutator estimate to exploit the
dissipative effect of the structural damping $(-\Delta)^\alpha u_{t}$ and to
overcome the essential difficulty: ""both the unbounded domain $\mathbb{R}^N$
and the supercritical nonlinearity cause that the Sobolev embedding loses its
compactness""; Meanwhile we show that there exists a supercritical index
$p_\alpha\equiv\frac{N+4\alpha}{N-4\alpha}$ depending on $\alpha$ such that
when the growth exponent $p$ of the nonlinearity $g(u)$ is up to the
supercritical range: $1\leqslant p<p_\alpha$: (i) the IVP of the equation is
well-posed and its solution is of additionally global smoothness when $t>0$;
(ii) the related solution semigroup possesses a global attractor
$\mathcal{A}_\alpha$ in natural energy space for each $\alpha\in (1/2, 1)$;
(iii) the family of global attractors $\{\mathcal{A}_\alpha\}_{\alpha\in (1/2,
1) }$ is upper semicontinuous at each point $\alpha_0\in (1/2, 1)$.",1905.06778v1
2019-05-20,Quantum parameter-estimation of frequency and damping of a harmonic-oscillator,"We determine the quantum Cram\'er-Rao bound for the precision with which the
oscillator frequency and damping constant of a damped quantum harmonic
oscillator in an arbitrary Gaussian state can be estimated. This goes beyond
standard quantum parameter estimation of a single mode Gaussian state for which
typically a mode of fixed frequency is assumed. We present a scheme through
which the frequency estimation can nevertheless be based on the known results
for single-mode quantum parameter estimation with Gaussian states. Based on
these results, we investigate the optimal measurement time. For measuring the
oscillator frequency, our results unify previously known partial results and
constitute an explicit solution for a general single-mode Gaussian state.
Furthermore, we show that with existing carbon nanotube resonators (see J.
Chaste et al.~Nature Nanotechnology 7, 301 (2012)) it should be possible to
achieve a mass sensitivity of the order of an electron mass $\text{Hz}^{-1/2}$.",1905.08288v1
2019-05-24,Damped oscillations of the probability of random events followed by absolute refractory period: exact analytical results,"There are numerous examples of natural and artificial processes that
represent stochastic sequences of events followed by an absolute refractory
period during which the occurrence of a subsequent event is impossible. In the
simplest case of a generalized Bernoulli scheme for uniform random events
followed by the absolute refractory period, the event probability as a function
of time can exhibit damped transient oscillations. Using stochastically-spiking
point neuron as a model example, we present an exact and compact analytical
description for the oscillations without invoking the standard renewal theory.
The resulting formulas stand out for their relative simplicity, allowing one to
analytically obtain the amplitude damping of the 2nd and 3rd peaks of the event
probability.",1905.10172v3
2020-07-01,"An integrable family of torqued, damped, rigid rotors","Expositions of the Euler equations for the rotation of a rigid body often
invoke the idea of a specially damped system whose energy dissipates while its
angular momentum magnitude is conserved in the body frame. An attempt to
explicitly construct such a damping function leads to a more general, but still
integrable, system of cubic equations whose trajectories are confined to nested
sets of quadric surfaces in angular momentum space. For some choices of
parameters, the lines of fixed points along both the largest and smallest
moment of inertia axes can be simultaneously attracting. Limiting cases are
those that conserve either the energy or the magnitude of the angular momentum.
Parallels with rod mechanics, micromagnetics, and particles with effective mass
are briefly discussed.",2007.00707v1
2020-07-10,Approximate Time-Optimal Trajectories for Damped Double Integrator in 2D Obstacle Environments under Bounded Inputs,"This article provides extensions to existing path-velocity decomposition
based time optimal trajectory planning algorithm \cite{kant1986toward} to
scenarios in which agents move in 2D obstacle environment under double
integrator dynamics with drag term (damped double integrator). Particularly, we
extend the idea of a tangent graph \cite{liu1992path} to $\calC^1$-Tangent
graph to find continuously differentiable ($\calC^1$) shortest path between any
two points. $\calC^1$-Tangent graph has a continuously differentiable
($\calC^1$) path between any two nodes. We also provide analytical expressions
for a near time-optimal velocity profile for an agent moving on these shortest
paths under the damped double integrator with bounded acceleration.",2007.05155v2
2013-08-02,Spin pumping damping and magnetic proximity effect in Pd and Pt spin-sink layers,"We investigated the spin pumping damping contributed by paramagnetic layers
(Pd, Pt) in both direct and indirect contact with ferromagnetic
Ni$_{81}$Fe$_{19}$ films. We find a nearly linear dependence of the
interface-related Gilbert damping enhancement $\Delta\alpha$ on the heavy-metal
spin-sink layer thicknesses t$_\textrm{N}$ in direct-contact
Ni$_{81}$Fe$_{19}$/(Pd, Pt) junctions, whereas an exponential dependence is
observed when Ni$_{81}$Fe$_{19}$ and (Pd, Pt) are separated by \unit[3]{nm} Cu.
We attribute the quasi-linear thickness dependence to the presence of induced
moments in Pt, Pd near the interface with Ni$_{81}$Fe$_{19}$, quantified using
X-ray magnetic circular dichroism (XMCD) measurements. Our results show that
the scattering of pure spin current is configuration-dependent in these systems
and cannot be described by a single characteristic length.",1308.0450v2
2013-08-10,CESR Test Accelerator,"The Cornell Electron Storage Ring (CESR) was reconfigured in 2008 as a test
accelerator to investigate the physics of ultra-low emittance damping rings.
During the approximately 40 days/year available for dedicated operation as a
test accelerator, specialized instrumentation is used to measure growth and
mitigation of the electron cloud, emittance growth due to electron cloud,
intra-beam scattering, and ions, and single and multi-bunch instabilities
generated by collective effects. The flexibility of the CESR guide field optics
and the integration of accelerator modeling codes with the control system have
made possible an extraordinary range of experiments. Findings at CesrTA with
respect to electron cloud effects, emittance tuning techniques, and beam
instrumentation for measuring electron cloud, beam sizes, and beam positions
are the basis for much of the design of the ILC damping rings as documented in
the ILC-Technical Design Report. The program has allowed the Cornell group to
cultivate the kind of talent and expertise that will be absolutely essential to
the final engineering design, and commissioning of the damping rings for a
linear collider.",1308.2325v1
2014-03-10,Quantum Fisher Information of W States in Decoherence Channels,"We study the quantum Fisher information (QFI) of W states analytically with
respect to SU(2) rotations in the basic decoherence channels i.e. depolarizing
(DPC), amplitude damping (ADC) and phase damping (PDC), and present the
interesting behavior of QFI of W states, especially when compared to that of
GHZ states [Ma et al., Phys. Rev. A, 84, 022302 (2011)]. We find that when
initially pure W states are under decoherence, i) DPC: as decoherence starts
and increases, QFI smoothly decays; ii) ADC: just as decoherence starts, QFI
exhibits a sudden drop to the shot noise level and as decoherence increases,
QFI continues to decrease to zero and then increases back to the shot noise
level; iii) PDC: just as decoherence starts, a sudden death of QFI occurs and
QFI remains zero for any rate of decoherence, therefore W states in phase
damping channel do not provide phase sensitivity. We also find that, on the
contrary to GHZ states, pure or decohered W states are not sensitive with
respect to rotations in z direction and the sensitivities with respect to
rotations in x and y directions are equal to each other, implying no sudden
change points of QFI due to competition between directions.",1403.2376v1
2014-03-14,Silk damping at a redshift of a billion: a new limit on small-scale adiabatic perturbations,"We study the dissipation of small-scale adiabatic perturbations at early
times when the Universe is hotter than T ~ 0.5 keV. When the wavelength falls
below the damping scale 1/kD, the acoustic modes diffuse and thermalize,
causing entropy production. Before neutrino decoupling, kD is primarily set by
the neutrino shear viscosity, and we study the effect of acoustic damping on
the relic neutrino number, primordial nucleosynthesis, dark-matter freeze-out,
and baryogenesis. This sets a new limit on the amplitude of primordial
fluctuations of DeltaR^2 < 0.007 at 10^4/Mpc< k < 10^5/Mpc and a model
dependent limit of DeltaR^2 < 0.3 at k < 10^{20-25}/Mpc.",1403.3697v1
2016-11-25,Bulk viscous corrections to screening and damping in QCD at high temperatures,"Non-equilibrium corrections to the distribution functions of quarks and
gluons in a hot and dense QCD medium modify the ""hard thermal loops"" (HTL). The
HTLs determine the retarded, advanced, and symmetric (time-ordered) propagators
for gluons with soft momenta as well as the Debye screening and Landau damping
mass scales. We compute such corrections to a thermal as well as to a
non-thermal fixed point.The screening and damping mass scales are sensitive to
the bulk pressure and hence to (pseudo-) critical dynamical scaling of the bulk
viscosity in the vicinity of a second-order critical point. This could be
reflected in the properties of quarkonium bound states in the deconfined phase
and in the dynamics of soft gluon fields.",1611.08379v2
2017-01-04,Hamiltonian of mean force and a damped harmonic oscillator in an anisotropic medium,"The quantum dynamics of a damped harmonic oscillator is investigated in the
presence of an anisotropic heat bath. The medium is modeled by a continuum of
three dimensional harmonic oscillators and anisotropic coupling is treated by
introducing tensor coupling functions. Starting from a classical Lagrangian,
the total system is quantized in the framework of the canonical quantization.
Following Fano technique, Hamiltonian of the system is diagonalized in terms of
creation and annihilation operators that are linear combinations of the basic
dynamical variables. Using the diagonalized Hamiltonian, the mean force
internal energy, free energy and entropy of the damped oscillator are
calculated.",1701.00964v2
2017-01-30,Quantization of energy and weakly turbulent profiles of the solutions to some damped second order evolution equations,"We consider a second order equation with a linear ""elastic"" part and a
nonlinear damping term depending on a power of the norm of the velocity. We
investigate the asymptotic behavior of solutions, after rescaling them suitably
in order to take into account the decay rate and bound their energy away from
zero.We find a rather unexpected dichotomy phenomenon. Solutions with finitely
many Fouriercomponents are asymptotic to solutions of the linearized
equationwithout damping, and exhibit some sort of equipartition of theenergy
among the components. Solutions with infinitely manyFourier components tend to
zero weakly but not strongly. We showalso that the limit of the energy of
solutions depends only on thenumber of their Fourier components.The proof of
our results is inspired by the analysis of asimplified model which we devise
through an averaging procedure,and whose solutions exhibit the same asymptotic
properties as thesolutions to the original equation.",1701.08604v1
2017-04-07,Underdamped stochastic harmonic oscillator,"We investigate stationary states of the linear damped stochastic oscillator
driven by L\'evy noises. In the long time limit kinetic and potential energies
of the oscillator do not fulfill the equipartition theorem and their
distributions follow the power-law asymptotics. At the same time, partition of
the mechanical energy is controlled by the damping coefficient. We show that in
the limit of vanishing damping a stochastic analogue of the equipartition
theorem can be proposed, namely the statistical properties of potential and
kinetic energies attain distributions characterized by the same width. Finally,
we demonstrate that the ratio of instantaneous kinetic and potential energies
which signifies departure from the mechanical energy equipartition, follows
universal power-law asymptotics.",1704.02119v2
2017-04-11,CoFeAlB alloy with low damping and low magnetization for spin transfer torque switching,"We investigate the effect of Al doping on the magnetic properties of the
alloy CoFeB. Comparative measurements of the saturation magnetization, the
Gilbert damping parameter $\alpha$ and the exchange constant as a function of
the annealing temperature for CoFeB and CoFeAlB thin films are presented. Our
results reveal a strong reduction of the magnetization for CoFeAlB in
comparison to CoFeB. If the prepared CoFeAlB films are amorphous, the damping
parameter $\alpha$ is unaffected by the Al doping in comparison to the CoFeB
alloy. In contrast, in the case of a crystalline CoFeAlB film, $\alpha$ is
found to be reduced. Furthermore, the x-ray characterization and the evolution
of the exchange constant with the annealing temperature indicate a similar
crystallization process in both alloys. The data proves the suitability of
CoFeAlB for spin torque switching properties where a reduction of the switching
current in comparison with CoFeB is expected.",1704.03326v1
2017-04-13,Quantum behaviour of open pumped and damped Bose-Hubbard trimers,"We propose and analyse analogs of optical cavities for atoms using three-well
inline Bose-Hubbard models with pumping and losses. With one well pumped and
one damped, we find that both the mean-field dynamics and the quantum
statistics show a qualitative dependence on the choice of damped well. The
systems we analyse remain far from equilibrium, although most do enter a
steady-state regime. We find quadrature squeezing, bipartite and tripartite
inseparability and entanglement, and states exhibiting the EPR paradox,
depending on the parameter regimes. We also discover situations where the
mean-field solutions of our models are noticeably different from the quantum
solutions for the mean fields. Due to recent experimental advances, it should
be possible to demonstrate the effects we predict and investigate in this
article.",1704.04021v1
2018-05-15,Simple Nonlinear Models with Rigorous Extreme Events and Heavy Tails,"Extreme events and the heavy tail distributions driven by them are ubiquitous
in various scientific, engineering and financial research. They are typically
associated with stochastic instability caused by hidden unresolved processes.
Previous studies have shown that such instability can be modeled by a
stochastic damping in conditional Gaussian models. However, these results are
mostly obtained through numerical experiments, while a rigorous understanding
of the underlying mechanism is sorely lacking. This paper contributes to this
issue by establishing a theoretical framework, in which the tail density of
conditional Gaussian models can be rigorously determined. In rough words, we
show that if the stochastic damping takes negative values, the tail is
polynomial; if the stochastic damping is nonnegative but takes value zero, the
tail is between exponential and Gaussian. The proof is established by
constructing a novel, product-type Lyapunov function, where a Feynman-Kac
formula is applied. The same framework also leads to a non-asymptotic large
deviation bound for long-time averaging processes.",1805.05615v3
2018-05-29,Gilbert damping in non-collinear magnetic system,"The modification of the magnetization dissipation or Gilbert damping caused
by an inhomogeneous magnetic structure and expressed in terms of a wave vector
dependent tensor $\underline{\alpha}(\vec{q})$ is investigated by means of
linear response theory. A corresponding expression for
$\underline{\alpha}(\vec{q})$ in terms of the electronic Green function has
been developed giving in particular the leading contributions to the Gilbert
damping linear and quadratic in $q$. Numerical results for realistic systems
are presented that have been obtained by implementing the scheme within the
framework of the fully relativistic KKR (Korringa-Kohn-Rostoker) band structure
method. Using the multilayered system (Cu/Fe$_{1-x}$Co$_x$/Pt)$_n$ as an
example for systems without inversion symmetry we demonstrate the occurrence of
non-vanishing linear contributions. For the alloy system bcc Fe$_{1-x}$Co$_x$
having inversion symmetry, on the other hand, only the quadratic contribution
is non-zero. As it is shown, this quadratic contribution does not vanish even
if the spin-orbit coupling is suppressed, i.e.\ it is a direct consequence of
the non-collinear spin configuration.",1805.11468v1
2008-07-07,Using squeezed field to preserve two-atom entanglement against spontaneous emissions,"Tunable interaction between two atoms in a cavity is realized by interacting
the two atoms with an extra controllable single-mode squeezed field. Such a
controllable interaction can be further used to control entanglement between
the two atoms against amplitude damping decoherence caused by spontaneous
emissions. For the independent amplitude damping decoherence channel,
entanglement will be lost completely without controls, while it can be
partially preserved by the proposed strategy. For the collective amplitude
damping decoherence channel, our strategy can enhance the entanglement compared
with the uncontrolled case when the entanglement of the uncontrolled stationary
state is not too large.",0807.0965v2
2008-07-17,Connecting high-redshift galaxy populations through observations of local Damped Lyman Alpha dwarf galaxies,"I report on observations of the z=0.01 dwarf galaxy SBS1543+593 which is
projected onto the background QSO HS1543+5921. As a star-forming galaxy first
noted in emission, this dwarf is playing a pivotal role in our understanding of
high-redshift galaxy populations, because it also gives rise to a Damped Lyman
Alpha system. This enabled us to analyze, for the first time, the chemical
abundance of $\alpha$ elements in a Damped Lyman Alpha galaxy using both,
emission and absorption diagnostics. We find that the abundances agree with one
another within the observational uncertainties. I discuss the implications of
this result for the interpretation of high-redshift galaxy observations. A
catalog of dwarf-galaxy--QSO projections culled from the Sloan Digital Sky
Survey is provided to stimulate future work.",0807.2853v1
2008-07-23,"Damped driven coupled oscillators: entanglement, decoherence and the classical limit","The interaction of (two-level) Rydberg atoms with dissipative QED cavity
fields can be described classically or quantum mechanically, even for very low
temperatures and mean number of photons, provided the damping constant is large
enough. We investigate the quantum-classical border, the entanglement and
decoherence of an analytically solvable model, analog to the atom-cavity
system, in which the atom (field) is represented by a (driven and damped)
harmonic oscillator. The maximum value of entanglement is shown to depend on
the initial state and the dissipation-rate to coupling-constant ratio. While in
the original model the atomic entropy never grows appreciably (for large
dissipation rates), in our model it reaches a maximum before decreasing.
Although both models predict small values of entanglement and dissipation, for
fixed times of the order of the inverse of the coupling constant and large
dissipation rates, these quantities decrease faster, as a function of the ratio
of the dissipation rate to the coupling constant, in our model.",0807.3715v1
2008-07-26,A Monte Carlo Method for Modeling Thermal Damping: Beyond the Brownian-Motion Master Equation,"The ""standard"" Brownian motion master equation, used to describe thermal
damping, is not completely positive, and does not admit a Monte Carlo method,
important in numerical simulations. To eliminate both these problems one must
add a term that generates additional position diffusion. He we show that one
can obtain a completely positive simple quantum Brownian motion, efficiently
solvable, without any extra diffusion. This is achieved by using a stochastic
Schroedinger equation (SSE), closely analogous to Langevin's equation, that has
no equivalent Markovian master equation. Considering a specific example, we
show that this SSE is sensitive to nonlinearities in situations in which the
master equation is not, and may therefore be a better model of damping for
nonlinear systems.",0807.4211v3
2008-07-31,Finite-dimensional attractors for the quasi-linear strongly-damped wave equation,"We present a new method of investigating the so-called quasi-linear strongly
damped wave equations $$ \partial_t^2u-\gamma\partial_t\Delta_x u-\Delta_x
u+f(u)= \nabla_x\cdot \phi'(\nabla_x u)+g $$ in bounded 3D domains. This method
allows us to establish the existence and uniqueness of energy solutions in the
case where the growth exponent of the non-linearity $\phi$ is less than 6 and
$f$ may have arbitrary polynomial growth rate. Moreover, the existence of a
finite-dimensional global and exponential attractors for the solution semigroup
associated with that equation and their additional regularity are also
established. In a particular case $\phi\equiv0$ which corresponds to the
so-called semi-linear strongly damped wave equation, our result allows to
remove the long-standing growth restriction $|f(u)|\leq C(1+ |u|^5)$.",0807.5078v1
2009-12-08,Coupling Photosphere and Corona: Linear and Turbulent Regimes,"In a recent work Grappin et al. [1] have shown that low- frequency movements
can be transmitted from one footpoint to the other along a magnetic loop, thus
mimicking a friction effect of the corona on the photosphere, and invalidating
the line-tying approximation. We consider here successively the effect of high
frequencies and turbulent damping on the process. We use a very simple
atmospheric model which allows to study analytically the laminar case, and to
study the turbulent case both using simple phenomenological arguments and a
more sophisticated turbulence model [2]. We find that, except when turbulent
damping is such that all turbulence is damped during loop traversal, coupling
still occurs between distant footpoints, and moreover the coronal field induced
by photospheric movements saturates at finite values.",0912.1497v1
2009-12-16,The role of $r$-mode damping in the thermal evolution of neutron stars,"The thermal evolution of neutron stars (NSs) is investigated by coupling with
the evolution of $\textit{r}$-mode instability that is described by a second
order model.The heating effect due to shear viscous damping of the
$\textit{r}$-modes enables us to understand the high temperature of two young
pulsars (i.e., PSR B0531+21 and RX J0822-4300) in the framework of the simple
$npe$ NS model, without superfluidity or exotic particles.Moreover, the light
curves predicted by the model within an acceptable parameter regime may
probably cover all of the young and middle-aged pulsars in the $\lg
T_s^{\infty}-\lg t$ panel, and an artificially strong $p$ superfluidity invoked
in some early works is not needed here. Additionally, by considering the
radiative viscous damping of the $\textit{r}$-modes, a surprising extra cooling
effect is found, which can even exceed the heating effect sometimes although
plays an ignorable role in the thermal history.",0912.3052v1
2009-12-25,Noisy non-transitive quantum games,"We study the effect of quantum noise in 3 by 3 entangled quantum games. By
considering different noisy quantum channels we analyze that how a two-player,
three-strategy Rock-Scissor-Paper game is influenced by the quantum noise. We
consider the winning non-transitive strategies R, S and P such as R beats S, S
beats P, and P beats R. The game behaves as a noiseless game for maximum value
of the quantum noise parameter. It is seen that Alice's payoff is heavily
influenced by the depolarizing noise as compared to the amplitude damping
noise. Depolarizing channel causes a monotonic decrease in players payoffs as
we increase the amount of of quantum noise. In case of amplitude damping
channel, the Alice's payoff function reaches its minimum for alpha=0.5 and is
symmetrical. This means that larger values of quantum noise influence the game
weakly. On the other hand, phase damping channel does not influence the game's
payoff. Furthermore, the game's Nash equilibrium and non-transitive character
of the game are not affected under the influence of quantum noise.",0912.4961v1
2011-11-20,Detection of picosecond magnetization dynamics of 50 nm magnetic dots down to the single dot regime,"We report an all-optical time-domain detection of picosecond magnetization
dynamics of arrays of 50 nm Ni80Fe20 (permalloy) dots down to the single
nanodot regime. In the single nanodot regime the dynamics reveals one dominant
resonant mode corresponding to the edge mode of the 50 nm dot with slightly
higher damping than that of the unpatterned thin film. With the increase in
areal density of the array both the precession frequency and damping increases
significantly due to the increase in magnetostatic interactions between the
nanodots and a mode splitting and sudden jump in apparent damping are observed
at an edge-to-edge separation of 50 nm.",1111.4625v1
2012-01-09,Universal response of optimal granular damping devices,"Granular damping devices constitute an emerging technology for the
attenuation of vibrations based on the dissipative nature of particle
collisions. We show that the performance of such devices is independent of the
material properties of the particles for working conditions where damping is
optimal. Even the suppression of a dissipation mode (collisional or frictional)
is unable to alter the response. We explain this phenomenon in terms of the
inelastic collapse of granular materials. These findings provide a crucial
standpoint for the design of such devices in order to achieve the desired low
maintenance feature that makes particle dampers particularly suitable to harsh
environments.",1201.1866v2
2012-01-09,Radiative energy loss reduction in an absorptive plasma,"The influence of the damping of radiation on the radiative energy loss
spectrum of a relativistic charge in an infinite, absorptive plasma is studied.
We find increasing reduction of the spectrum with increasing damping. Our
studies, which represent an Abelian approximation for the colour charge
dynamics in the quark-gluon plasma, may influence the analysis of jet quenching
phenomena observed in high-energy nuclear collisions. Here, we focus on a
formal discussion of the limiting behaviour with increasing radiation
frequency. In an absorptive (and polarizable) medium, this is determined by the
behaviour of the exponential damping factor entering the spectrum and the
formation time of radiation.",1201.1890v1
2012-01-10,Nonequilibrium Damping of Collective Motion of Homogeneous Cold Fermi Condensates with Feshbach Resonances,"Collisionless damping of a condensate of cold Fermi atoms, whose scattering
is controlled by a Feshbach resonance, is explored throughout the BCS and BEC
regimes when small perturbations on its phase and amplitude modes are turned on
to drive the system slightly out of equilibrium. Using a one-loop effective
action, we first recreate the known result that for a broad resonance the
amplitude of the condensate decays as $t^{-1/2}$ at late times in the BCS
regime whereas it decays as $t^{-3/2}$ in the BEC regime. We then examine the
case of an idealized narrow resonance, and find that this collective mode
decays as $t^{-3/2}$ throughout both the BCS and BEC regimes. Although this
seems to contradict earlier results that damping is identical for both broad
and narrow resonances, the breakdown of the narrow resonance limit restores
this universal behaviour. More measureably, the phase perturbation may give a
shift on the saturated value to which the collective amplitude mode decays,
which vanishes only in the deep BCS regime when the phase and amplitude modes
are decoupled.",1201.2019v1
2012-01-30,Modeling electricity spot prices using mean-reverting multifractal processes,"We discuss stochastic modeling of volatility persistence and
anti-correlations in electricity spot prices, and for this purpose we present
two mean-reverting versions of the multifractal random walk (MRW). In the first
model the anti-correlations are modeled in the same way as in an
Ornstein-Uhlenbeck process, i.e. via a drift (damping) term, and in the second
model the anti-correlations are included by letting the innovations in the MRW
model be fractional Gaussian noise with H < 1/2. For both models we present
approximate maximum likelihood methods, and we apply these methods to estimate
the parameters for the spot prices in the Nordic electricity market. The
maximum likelihood estimates show that electricity spot prices are
characterized by scaling exponents that are significantly different from the
corresponding exponents in stock markets, confirming the exceptional nature of
the electricity market. In order to compare the damped MRW model with the
fractional MRW model we use ensemble simulations and wavelet-based variograms,
and we observe that certain features of the spot prices are better described by
the damped MRW model. The characteristic correlation time is estimated to
approximately half a year.",1201.6137v1
2013-09-09,Characterization of the International Linear Collider damping ring optics,"A method is presented for characterizing the emittance dilution and dynamic
aperture for an arbitrary closed lattice that includes guide field magnet
errors, multipole errors and misalignments. This method, developed and tested
at the Cornell Electron Storage Ring Test Accelerator (CesrTA), has been
applied to the damping ring lattice for the International Linear Collider
(ILC). The effectiveness of beam based emittance tuning is limited by beam
position monitor (BPM) measurement errors, number of corrector magnets and
their placement, and correction algorithm. The specifications for damping ring
magnet alignment, multipole errors, number of BPMs, and precision in BPM
measurements are shown to be consistent with the required emittances and
dynamic aperture. The methodology is then used to determine the minimum number
of position monitors that is required to achieve the emittance targets, and how
that minimum depends on the location of the BPMs. Similarly, the maximum
tolerable multipole errors are evaluated. Finally, the robustness of each BPM
configuration with respect to random failures is explored.",1309.2248v3
2013-09-19,Van der Waals Coefficients for the Alkali-metal Atoms in the Material Mediums,"The damping coefficients for the alkali atoms are determined very accurately
by taking into account the optical properties of the atoms and three distinct
types of trapping materials such as Au (metal), Si (semi-conductor) and
vitreous SiO2 (dielectric). Dynamic dipole polarizabilities are calculated
precisely for the alkali atoms that reproduce the damping coefficients in the
perfect conducting medium within 0.2% accuracy. Upon the consideration of the
available optical data of the above wall materials, the damping coefficients
are found to be substantially different than those of the ideal conductor. We
also evaluated dispersion coefficients for the alkali dimers and compared them
with the previously reported values. These coefficients are fitted into a
ready-to-use functional form to aid the experimentalists the interaction
potentials only with the knowledge of distances.",1309.4897v1
2014-06-02,CMB $μ$ distortion from primordial gravitational waves,"We propose a new mechanism of generating the $\mu$ distortion in cosmic
microwave background (CMB) originated from primordial gravitational waves. Such
$\mu$ distortion is generated by the damping of the temperature anisotropies
through the Thomson scattering, even on scales larger than that of Silk
damping. This mechanism is in sharp contrast with that from the primordial
curvature (scalar) perturbations, in which the temperature anisotropies mainly
decay by Silk damping effects. We estimate the size of the $\mu$ distortion
from the new mechanism, which can be used to constrain the amplitude of
primordial gravitational waves on smaller scales independently from the CMB
anisotropies, giving more wide-range constraint on their spectral index by
combining the amplitude from the CMB anisotropies.",1406.0451v2
2014-06-04,Self-organized escape processes of linear chains in nonlinear potentials,"An enhancement of localized nonlinear modes in coupled systems gives rise to
a novel type of escape process. We study a spatially one dimensional set-up
consisting of a linearly coupled oscillator chain of $N$ mass-points situated
in a metastable nonlinear potential. The Hamilton-dynamics exhibits breather
solutions as a result of modulational instability of the phonon states. These
breathers localize energy by freezing other parts of the chain. Eventually this
localised part of the chain grows in amplitude until it overcomes the critical
elongation characterized by the transition state. Doing so, the breathers
ignite an escape by pulling the remaining chain over the barrier. Even if the
formation of singular breathers is insufficient for an escape, coalescence of
moving breathers can result in the required concentration of energy. Compared
to a chain system with linear damping and thermal fluctuations the breathers
help the chain to overcome the barriers faster in the case of low damping. With
larger damping, the decreasing life time of the breathers effectively inhibits
the escape process.",1406.0938v1
2014-06-08,Dissipation-driven squeezed and sub-Poissonian mechanical states in quadratic optomechanical systems,"In this work we study an optomechanical system in which there is a purely
quadratic optomechanical coupling between the optical and mechanical modes. The
optical mode is pumped by three coherent fields and the mechanical mode is
parametrically driven. We show that if the frequencies and amplitudes of both
optical and mechanical drivings are properly chosen, the optomechanical
interaction gives rise to an effective interaction, which, in the presence of
optical damping and in the absence of mechanical damping, has the squeezed
vacuum state and the squeezed one phonon state as dark states of the dynamics.
These states are well known for presenting quadrature squeezing and
sub-Poissonian statistics. However, even in the presence of mechanical damping
it is possible to find steady states with large degrees of quadrature squeezing
or strong sub-Poissonian statistics. Furthermore, we find a counter-intuitive
behavior in which a nonzero temperature of the mechanical environment allows
the observation of mechanical states with more pronounced sub-Poissonian
statistics.",1406.1987v3
2014-06-13,Frequency-dependent damping in propagating slow magneto-acoustic waves,"Propagating slow magneto-acoustic waves are often observed in polar plumes
and active region fan loops. The observed periodicities of these waves range
from a few minutes to few tens of minutes and their amplitudes were found to
decay rapidly as they travel along the supporting structure. Previously,
thermal conduction, compressive viscosity, radiation, density stratification,
and area divergence, were identified to be some of the causes for change in the
slow wave amplitude. Our recent studies indicate that the observed damping in
these waves is frequency dependent. We used imaging data from SDO/AIA, to study
this dependence in detail and for the first time from observations we attempted
to deduce a quantitative relation between damping length and frequency of these
oscillations. We developed a new analysis method to obtain this relation. The
observed frequency dependence does not seem to agree with the current linear
wave theory and it was found that the waves observed in the polar regions show
a different dependence from those observed in the on-disk loop structures
despite the similarity in their properties.",1406.3565v1
2014-06-24,Interface enhancement of Gilbert damping from first-principles,"The enhancement of Gilbert damping observed for Ni80Fe20 (Py) films in
contact with the non-magnetic metals Cu, Pd, Ta and Pt, is quantitatively
reproduced using first-principles scattering theory. The ""spin-pumping"" theory
that qualitatively explains its dependence on the Py thickness is generalized
to include a number of factors known to be important for spin transport through
interfaces. Determining the parameters in this theory from first-principles
shows that interface spin-flipping makes an essential contribution to the
damping enhancement. Without it, a much shorter spin-flip diffusion length for
Pt would be needed than the value we calculate independently.",1406.6225v2
2014-06-24,On finite density effects on cosmic reheating and moduli decay and implications for Dark Matter production,"We study the damping of an oscillating scalar field in a
Friedmann-Robertson-Walker spacetime by perturbative processes, taking into
account the finite density effects that interactions with the plasma of decay
products have on the damping rate. The scalar field may be identified with the
inflaton, in which case this process leads to the reheating of the universe
after inflation. It can also resemble a modulus that dominates the energy
density of the universe at later times. We find that the finite density
corrections to the damping rate can have a drastic effect on the thermal
history and considerably increase both, the maximal temperature in the early
universe and the reheating temperature at the onset of the radiation dominated
era. As a result abundance of some Dark Matter candidates may be considerably
larger than previously estimated. We give improved analytic estimates for the
maximal and the reheating temperatures and confirm them numerically in a simple
model.",1406.6243v2
2015-12-01,Epitaxial patterning of nanometer-thick Y3Fe5O12 films with low magnetic damping,"Magnetic insulators such as yttrium iron garnet, Y3Fe5O12, with extremely low
magnetic damping have opened the door for low power spin-orbitronics due to
their low energy dissipation and efficient spin current generation and
transmission. We demonstrate reliable and efficient epitaxial growth and
nanopatterning of Y3Fe5O12 thin-film based nanostructures on insulating
Gd3Ga5O12 substrates. In particular, our fabrication process is compatible with
conventional sputtering and liftoff, and does not require aggressive ion
milling which may be detrimental to the oxide thin films. Structural and
magnetic properties indicate good qualities, in particular low magnetic damping
of both films and patterned structures. The dynamic magnetic properties of the
nanostructures are systematically investigated as a function of the lateral
dimension. By comparing to ferromagnetic nanowire structures, a distinct edge
mode in addition to the main mode is identified by both experiments and
simulations, which also exhbits cross-over with the main mode upon varying the
width of the wires. The non-linear evolution of dynamic modes over
nanostructural dimensions highlights the important role of size confinement to
their material properties in magnetic devices where Y3Fe5O12 nanostructures
serve as the key functional component.",1512.00286v1
2015-12-03,Probing Bogoliubov quasiparticles in superfluid $^3$He with a 'vibrating-wire like' MEMS device,"We have measured the interaction between superfluid $^3$He-B and a
micro-machined goalpost-shaped device at temperatures below $0.2\,T_c$. The
measured damping follows well the theory developed for vibrating wires, in
which the Andreev reflection of quasiparticles in the flow field around the
moving structure leads to a nonlinear frictional force. At low velocities the
damping force is proportional to velocity while it tends to saturate for larger
excitations. Above a velocity of 2.6$\,$mms$^{-1}$ the damping abruptly
increases, which is interpreted in terms of Cooper-pair breaking.
Interestingly, this critical velocity is significantly lower than reported with
other mechanical probes immersed in superfluid $^3$He. Furthermore, we report
on a nonlinear resonance shape for large motion amplitudes that we interpret as
an inertial effect due to quasiparticle friction, but other mechanisms could
possibly be invoked as well.",1512.01033v1
2016-05-06,Multidimensional Thermoelasticity for Nonsimple Materials -- Well-Posedness and Long-Time Behavior,"An initial-boundary value problem for the multidimensional type III
thermoelaticity for a nonsimple material with a center of symmetry is
considered. In the linear case, the well-posedness with and without
Kelvin-Voigt and/or frictional damping in the elastic part as well as the lack
of exponential stability in the elastically undamped case is proved. Further, a
frictional damping for the elastic component is shown to lead to the
exponential stability. A Cattaneo-type hyperbolic relaxation for the thermal
part is introduced and the well-posedness and uniform stability under a
nonlinear frictional damping are obtained using a compactness-uniqueness-type
argument. Additionally, a connection between the exponential stability and
exact observability for unitary $C_{0}$-groups is established.",1605.02049v1
2016-05-16,The Cauchy problem for the nonlinear damped wave equation with slowly decaying data,"We study the Cauchy problem for the nonlinear damped wave equation and
establish the large data local well-posedness and small data global
well-posedness with slowly decaying initial data. We also prove that the
asymptotic profile of the global solution is given by a solution of the
corresponding parabolic problem, which shows that the solution of the damped
wave equation has the diffusion phenomena. Moreover, we show blow-up of
solution and give the estimate of the lifespan for a subcritical nonlinearity.
In particular, we determine the critical exponent for any space dimension.",1605.04616v2
2016-05-20,High-frequency behavior of FeN thin films fabricated by reactive sputtering,"We investigated high-frequency behavior of FeN thin films prepared by
reactive sputtering through ferromagnetic resonance (FMR) and its relationship
with the static magnetic properties. The FMR was observed in the frequency
range from 2 to 18 GHz in the FeN films fabricated at proper nitrogen flow rate
(NFR). In those FeN thin films, a decrease of the saturation magnetization and
the corresponding decrease of the FMR frequency were observed as NFR was
increased during the deposition. The external field dependences of the FMR
frequencies were well fit to the Kittel formula and the Land\'e g-factors
determined from the fit were found to be very close to the free electron value.
The high-field damping parameters were almost insensitive to the growth
condition of NFR. However, the low-field damping parameters exhibited high
sensitivity to NFR very similar to the dependence of the hard-axis coercivity
on NFR, suggesting that extrinsic material properties such as impurities and
defect structures could be important in deciding the low-field damping
behavior.",1605.06179v1
2016-05-26,Thickness and temperature dependence of the magnetodynamic damping of pulsed laser deposited $\text{La}_{0.7}\text{Sr}_{0.3}\text{MnO}_3$ on (111)-oriented SrTi$\text{O}_3$,"We have investigated the magnetodynamic properties of
$\text{La}_{0.7}\text{Sr}_{0.3}\text{MnO}_3$ (LSMO) films of thickness 10, 15
and 30 nm grown on (111)-oriented SrTi$\text{O}_3$ (STO) substrates by pulsed
laser deposition. Ferromagnetic resonance (FMR) experiments were performed in
the temperature range 100--300 K, and the magnetodynamic damping parameter
$\alpha$ was extracted as a function of both film thickness and temperature. We
found that the damping is lowest for the intermediate film thickness of 15 nm
with $\alpha \approx 2 \cdot 10^{-3}$, where $\alpha$ is relatively constant as
a function of temperature well below the Curie temperature of the respective
films.",1605.08195v2
2016-12-07,Investigation of Stimulated Brillouin Scattering in Laser-Plasma Interactions,"In this paper, we present our numerical simulation results on the Stimulated
Brillouin Scattering (SBS) with injection of an ordinary mode (O-mode)
electromagnetic wave (our pump wave) with frequencies 70 GHz and 110 GHz.
Solving the Fourier transformed Vlasov equation in the velocity space, creates
a profile for distribution function. Time evolution of the distribution
function is investigated as well. Considering an average density for plasma
fusion (n_{0} ~ 10^{19} m^{-3}), we gain a profile for density. Then
two-dimensional instability rate for SBS is obtained. So, the fluctuation of
distribution function affects density and again density affects instability
rate. Increasing the incident light wave frequency causes the instability
growth rate to decrease. Time evolution shows a clear damping for instability
rate since the pump wave's energy is absorbed in plasma (plasma heating).
Furthermore, changing Landau damping for ion acoustic waves (IAW) by changing
ion-to-electron temperature ratio is presented as well, because this damping is
more dominant in high temperatures.",1612.02214v1
2016-12-07,Gilbert damping of magnetostatic modes in a yttrium iron garnet sphere,"The magnetostatic mode (MSM) spectrum of a 300$\mu$m diameter single
crystalline sphere of yttrium iron garnet is investigated using broadband
ferromagnetic resonance (FMR). The individual MSMs are identified via their
characteristic dispersion relations and the corresponding mode number tuples
$(nmr)$ are assigned. Taking FMR data over a broad frequency and magnetic field
range allows to analyze both the Gilbert damping parameter~$\alpha$ and the
inhomogeneous line broadening contribution to the total linewidth of the MSMs
separately. The linewidth analysis shows that all MSMs share the same Gilbert
damping parameter $\alpha=2.7(5) \times 10^{-5}$ irrespective of their mode
index. In contrast, the inhomogeneous line broadening shows a pronounced mode
dependence. This observation is modeled in terms of two-magnon scattering
processes of the MSMs into the spin-wave manifold, mediated by surface and
volume defects.",1612.02360v1
2016-12-08,Damped spin-wave excitations in the itinerant antiferromagnet $γ$-Fe$_{0.7}$Mn$_{0.3}$,"The collective spin-wave excitations in the antiferromagnetic state of
$\gamma$-Fe$_{0.7}$Mn$_{0.3}$ were investigated using the inelastic neutron
scattering technique. The spin excitations remain isotropic up to the high
excitation energy, ${\hbar\omega}= 78$ meV. The excitations gradually become
broad and damped above 40 meV. The damping parameter ${\gamma}$ reaches 110(16)
meV at ${\hbar\omega} = 78$ meV, which is much larger than that for other
metallic compounds, e.g., CaFe$_2$As$_2$ (24 meV),
La$_{2-2x}$Sr$_{1+2x}$Mn$_2$O$_7$ ($52-72$ meV), and Mn$_{90}$Cu$_{10}$ (88
meV). In addition, the spin-wave dispersion shows a deviation from the relation
$({\hbar\omega})^2 = c^2q^2 + {\Delta}^2$ above 40 meV. The group velocity
above this energy increases to 470(40) meV{\AA}, which is higher than that at
the low energies, $c = 226(5)$ meV{\AA}. These results could suggest that the
spin-wave excitations merge with the continuum of the individual particle-hole
excitations at 40 meV.",1612.02515v2
2016-12-09,How strong a logistic damping can prevent blow-up for the minimal Keller-Segel chemotaxis system?,"In this paper, we study the minimal Keller-Segel model with a logistic source
and obtain quantitative and qualitative descriptions of the competition between
logistic damping and other ingredient, especially, chemotactic aggregation to
guarantee boundedness and convergence. More specifically, we establish how
precisely strong a logistic source can prevent blow-up, and then we obtain an
explicit relationship between logistic damping and other ingredient,
especially, chemotactic aggregation so that convergences are ensured and their
respective convergence rates are explicitly calculated out. Known results in
the literature are completed and refined.
  Furthermore, our findings provide clues on how to produce blowup solutions
for KS chemotaxis models with logistic sources.",1612.03024v2
2016-12-28,Quantum coherence of two-qubit over quantum channels with memory,"Using the axiomatic definition of the coherence measure, such as the $l_{1}$
norm and the relative entropy, we study the phenomena of two-qubit system
quantum coherence through quantum channels where successive uses of the
channels are memory. Different types of noisy channels with memory, such as
amplitude damping, phase-damping, and depolarizing channels effect on quantum
coherence have been discussed in detail. The results show that, quantum
channels with memory can efficiently protect coherence from noisy channels.
Particularly, as channels with perfect memory, quantum coherence is unaffected
by the phase damping as well as depolarizing channels. Besides, we also
investigate the cohering and decohering power of quantum channels with memory.",1612.08791v1
2017-06-01,Global Stabilization of the Navier-Stokes-Voight and the damped nonlinear wave equations by finite number of feedback controllers,"In this paper we introduce a finite-parameters feedback control algorithm for
stabilizing solutions of the Navier-Stokes-Voigt equations, the strongly damped
nonlinear wave equations and the nonlinear wave equation with nonlinear damping
term, the Benjamin-Bona-Mahony-Burgers equation and the KdV-Burgers equation.
This algorithm capitalizes on the fact that such infinite-dimensional
dissipative dynamical systems posses finite-dimensional long-time behavior
which is represented by, for instance, the finitely many determining parameters
of their long-time dynamics, such as determining Fourier modes, determining
volume elements, determining nodes , etc..The algorithm utilizes these finite
parameters in the form of feedback control to stabilize the relevant solutions.
For the sake of clarity, and in order to fix ideas, we focus in this work on
the case of low Fourier modes feedback controller, however, our results and
tools are equally valid for using other feedback controllers employing other
spatial coarse mesh interpolants.",1706.00162v1
2017-06-08,Realistic clocks for a Universe without time,"There are a number of problematic features within the current treatment of
time in physical theories, including the ""timelessness"" of the Universe as
encapsulated by the Wheeler-DeWitt equation. This paper considers one
particular investigation into resolving this issue; a conditional probability
interpretation that was first proposed by Page and Wooters. Those authors
addressed the apparent timelessness by subdividing a faux Universe into two
entangled parts, ""the clock"" and ""the remainder of the Universe"", and then
synchronizing the effective dynamics of the two subsystems by way of
conditional probabilities. The current treatment focuses on the possibility of
using a (somewhat) realistic clock system; namely, a coherent-state description
of a damped harmonic oscillator. This clock proves to be consistent with the
conditional probability interpretation; in particular, a standard evolution
operator is identified with the position of the clock playing the role of time
for the rest of the Universe. Restrictions on the damping factor are determined
and, perhaps contrary to expectations, the optimal choice of clock is not
necessarily one of minimal damping.",1706.02531v1
2017-06-26,High $β$ Effects on Cosmic Ray Streaming in Galaxy Clusters,"Diffuse, extended radio emission in galaxy clusters, commonly referred to as
radio halos, indicate the presence of high energy cosmic ray (CR) electrons and
cluster-wide magnetic fields. We can predict from theory the expected surface
brightness of a radio halo, given magnetic field and CR density profiles.
Previous studies have shown that the nature of CR transport can radically
effect the expected radio halo emission from clusters (Wiener et al. 2013).
Reasonable levels of magnetohydrodynamic (MHD) wave damping can lead to
significant CR streaming speeds. But a careful treatment of MHD waves in a high
$\beta$ plasma, as expected in cluster environments, reveals damping rates may
be enhanced by a factor of $\beta^{1/2}$. This leads to faster CR streaming and
lower surface brightnesses than without this effect. In this work we re-examine
the simplified, 1D Coma cluster simulations (with radial magnetic fields) of
Wiener et al. (2013) and discuss observable consequences of this high $\beta$
damping. Future work is required to study this effect in more realistic
simulations.",1706.08525v2
2017-07-02,Metastability of Kolmogorov flows and inviscid damping of shear flows,"First, we consider Kolmogorov flow (a shear flow with a sinusoidal velocity
profile) for 2D Navier-Stokes equation on a torus. Such flows, also called bar
states, have been numerically observed as one type of metastable states in the
study of 2D turbulence. For both rectangular and square tori, we prove that the
non-shear part of perturbations near Kolmogorov flow decays in a time scale
much shorter than the viscous time scale. The results are obtained for both the
linearized NS equations with any initial vorticity in L^2, and the nonlinear NS
equation with initial L^2 norm of vorticity of the size of viscosity. In the
proof, we use the Hamiltonian structure of the linearized Euler equation and
RAGE theorem to control the low frequency part of the perturbation. Second, we
consider two classes of shear flows for which a sharp stability criterion is
known. We show the inviscid damping in a time average sense for non-shear
perturbations with initial vorticity in L^2. For the unstable case, the
inviscid damping is proved on the center space. Our proof again uses the
Hamiltonian structure of the linearized Euler equation and an instability index
theory recently developed by Lin and Zeng for Hamiltonian PDEs.",1707.00278v1
2017-10-13,Hydrodynamic-to-ballistic crossover in Dirac fluid,"We develop an exactly solvable classical kinetic model of transport in Dirac
materials accounting for strong electron-electron (e-e) and electron-hole (e-h)
collisions. We use this model to track the evolution of graphene conductivity
and properties of its collective excitations across the
hydrodynamic-to-ballistic crossover. We find the relaxation rate of electric
current by e-e collisions that is possible due to the lack of Galilean
invariance, and introduce a universal numerical measure of this non-invariance
in arbitrary dimension. We find the two branches of collective excitations in
the Dirac fluid: plasmons and electron-hole sound. The sound waves have small
viscous damping at the neutrality point both in the hydrodynamic and ballistic
regimes, but acquire large damping due to e-h friction even at slight doping.
On the contrary, plasmons acquire strong frictional damping at the neutrality
point and become well-defined in doped samples.",1710.05054v3
2017-10-13,The second hyperpolarizability of systems described by the space-fractional Schrodinger equation,"The static second hyperpolarizability is derived from the space-fractional
Schr\""{o}dinger equation in the particle-centric view. The Thomas-Reiche-Kuhn
sum rule matrix elements and the three-level ansatz determines the maximum
second hyperpolarizability for a space-fractional quantum system. The total
oscillator strength is shown to decrease as the space-fractional parameter
$\alpha$ decreases, which reduces the optical response of a quantum system in
the presence of an external field. This damped response is caused by the
wavefunction dependent position and momentum commutation relation. Although the
maximum response is damped, we show that the one-dimensional quantum harmonic
oscillator is no longer a linear system for $\alpha \neq 1$, where the second
hyperpolarizability becomes negative before ultimately damping to zero at the
lower fractional limit of $\alpha \rightarrow 1/2$.",1710.05099v2
2017-12-03,Explaining the DAMPE $e^+ e^-$ excess using the Higgs triplet model with a vector dark matter,"We explain the $e^+ e^-$ excess observed by the DAMPE Collaboration using a
dark matter model based upon the Higgs triplet model and an additional hidden
$SU(2)_X$ gauge symmetry. Two of the $SU(2)_X$ gauge bosons are stable due to a
residual discrete symmetry and serve as the dark matter candidate. We search
the parameter space for regions that can explain the observed relic abundance,
and compute the flux of $e^+ e^-$ coming from a nearby dark matter subhalo.
With the inclusion of background cosmic rays, we show that the model can render
a good fit to the entire energy spectrum covering the AMS-02, Fermi-LAT and
DAMPE data.",1712.00793v2
2017-12-06,Explain DAMPE Results by Dark Matter With Hierarchical Lepton-Specific Yukawa Interactions,"We propose to interpret the DAMPE electron excess at 1.5 TeV through scalar
or Dirac fermion dark matter (DM) annihilation with doubly charged scalar
mediators that have lepton-specific Yukawa couplings. Hierarchy of such
lepton-specific Yukawa couplings is generated through the Froggatt-Nielsen
mechanism, so that the dark matter annihilation products can be dominantly
electrons. Stringent constraints from LEP2 on intermediate vector boson
production can be evaded in our scenarios. In the case of scalar DM, we discuss
one scenario with DM annihilating directly to leptons and the other scenario
with DM annihilating to scalar mediators followed by their decays. We also
discuss the Breit-Wigner resonant enhancement and the Sommerfeld enhancement in
case that the s-wave annihilation process is small or helicity suppressed. With
both types of enhancement, constraints on the parameters can be relaxed and new
ways for model building will be open in explaining the DAMPE results.",1712.02381v3
2017-12-08,Kinetic damping in the spectra of the spherical impedance probe,"The impedance probe is a measurement device to measure plasma parameter like
electron density. It consists of one electrode connected to a network analyzer
via a coaxial cable and is immersed into a plasma. A bias potential superposed
with an alternating potential is applied to the electrode and the response of
the plasma is measured. Its dynamical interaction with the plasma in
electrostatic, kinetic description can be modeled in an abstract notation based
on functional analytic methods. These methods provide the opportunity to derive
a general solution, which is given as the response function of the probe-plasma
system. It is defined by the matrix elements of the resolvent of an appropriate
dynamical operator. Based on the general solution a residual damping for
vanishing pressure can be predicted and can only be explained by kinetic
effects. Within this manuscript an explicit response function of the spherical
impedance probe is derived. Therefore, the resolvent is determined by its
algebraic representation based on an expansion in orthogonal basis functions.
This allows to compute an approximated response function and its corresponding
spectra. These spectra show additional damping due to kinetic effects and are
in good agreement with former kinetically determined spectra.",1712.03126v1
2017-12-14,DAMPE squib? Significance of the 1.4 TeV DAMPE excess,"We present a Bayesian and frequentist analysis of the DAMPE charged cosmic
ray spectrum. The spectrum, by eye, contained a spectral break at about 1 TeV
and a monochromatic excess at about 1.4 TeV. The break was supported by a Bayes
factor of about $10^{10}$ and we argue that the statistical significance was
resounding. We investigated whether we should attribute the excess to dark
matter annihilation into electrons in a nearby subhalo. We found a local
significance of about $3.6\sigma$ and a global significance of about
$2.3\sigma$, including a two-dimensional look-elsewhere effect by simulating
1000 pseudo-experiments. The Bayes factor was sensitive to our choices of
priors, but favoured the excess by about 2 for our choices. Thus, whilst
intriguing, the evidence for a signal is not currently compelling.",1712.05089v1
2017-12-15,Radiative Seesaw Model and DAMPE Excess from Leptophilic Gauge Symmetry,"In the light of the $e^{+}+e^{-}$ excess observed by DAMPE experiment, we
propose an anomaly-free radiative seesaw model with an alternative leptophilic
$U(1)_X$ gauge symmetry. In the model, only right-handed leptons are charged
under $U(1)_X$ symmetry. The tiny Dirac neutrino masses are generated at
one-loop level and charged leptons acquire masses though the type-I seesaw-like
mechanism with heavy intermediate fermions. In order to cancel the anomaly,
irrational $U(1)_{X}$ charge numbers are assigned to some new particles. After
the spontaneous breaking of $U(1)_{X}$ symmetry, the dark $Z_{2}$ symmetry
could appear as a residual symmetry such that the stability of inert particles
with irrational charge numbers are guaranteed, naturally leading to stable DM
candidates. We show that the Dirac fermion DM contained in the model can
explain the DAMPE excess. Meanwhile, experimental constraints from DM relic
density, direct detection, LEP and anomalous magnetic moments are satisfied.",1712.05722v2
2017-12-19,Damping of Josephson oscillations in strongly correlated one-dimensional atomic gases,"We study Josephson oscillations of two strongly correlated one-dimensional
bosonic clouds separated by a localized barrier. Using a quantum-Langevin
approach and the exact Tonks-Girardeau solution in the impenetrable-boson
limit, we determine the dynamical evolution of the particle-number imbalance,
displaying an effective damping of the Josephson oscillations which depends on
barrier height, interaction strength and temperature. We show that the damping
originates from the quantum and thermal fluctuations intrinsically present in
the strongly correlated gas. Thanks to the density-phase duality of the model,
the same results apply to particle-current oscillations in a one-dimensional
ring where a weak barrier couples different angular momentum states.",1712.06949v2
2017-12-21,The gluon condensation effects in the DAMPE cosmic ray spectrum of electrons and positrons,"Gluons dominate the proton behavior at high energy collisions, they can be
condensed at ultra high energy. The collisions of the accelerated high energy
protons with interplanetary matter in cosmic rays will produce a huge number of
secondary particles at the gluon condensate energy region, which break the
primary power-law of cosmic rays. The above predictions seem to be consistent
with the recent DAMPE data concerning the electron plus positron spectra. We
find that the smoothly broken power-law at $\sim 0.9 TeV$ and $3\sim 4 TeV$ in
the DAMPE data can be understood as the gluon condensation effects in proton.",1712.07868v2
2017-12-22,Low-momentum dynamic structure factor of a strongly interacting Fermi gas at finite temperature: The Goldstone phonon and its Landau damping,"We develop a microscopic theory of dynamic structure factor to describe the
Bogoliubov-Anderson-Goldstone phonon mode and its damping rate in a strongly
interacting Fermi gas at finite temperature. It is based on a density
functional approach - the so-called superfluid local density approximation. The
accuracy of the theory is quantitatively examined by comparing the theoretical
predictions with the recent experimental measurements for the local dynamic
structure factor of a nearly homogeneous unitary Fermi gas at low transferred
momentum {[}S. Hoinka \textit{et al.}, Nat. Phys. \textbf{13}, 943 (2017){]},
without any free parameters. We calculate the dynamic structure factor as
functions of temperature and transferred momentum, and determine the
temperature evolution of the phonon damping rate, by considering the dominant
decay process of the phonon mode via scatterings off fermionic quasiparticles.
These predictions can be confronted with future Bragg scattering experiments on
a unitary Fermi gas near the superfluid transition.",1712.08318v1
2017-12-22,A brief summary of nonlinear echoes and Landau damping,"In this expository note we review some recent results on Landau damping in
the nonlinear Vlasov equations, focusing specifically on the recent
construction of nonlinear echo solutions by the author [arXiv:1605.06841] and
the associated background. These solutions show that a straightforward
extension of Mouhot and Villani's theorem on Landau damping to Sobolev spaces
on $\mathbb T^n_x \times \mathbb R^n_v $ is impossible and hence emphasize the
subtle dependence on regularity of phase mixing problems. This expository note
is specifically aimed at mathematicians who study the analysis of PDEs, but not
necessarily those who work specifically on kinetic theory. However, for the
sake of brevity, this review is certainly not comprehensive.",1712.08498v1
2017-12-28,Coherence evolution in two-qubit system going through amplitude damping channel,"In this paper, we analyze the evolution of quantum coherence in a two-qubit
system going through the amplitude damping channel. After they have gone
through this channel many times, we analyze the systems with respect to the
coherence of their output states. When only one subsystem goes through the
channel, frozen coherence occurs if and only if this subsystem is incoherent
and an auxiliary condition is satisfied for the other subsystem. When two
subsystems go through this quantum channel, quantum coherence can be frozen if
and only if the two subsystems are both incoherent. We also investigate the
evolution of coherence for maximally incoherent-coherent states and derive an
equation for the output states after one or two subsystems have gone through
the amplitude damping channel.",1712.09769v1
2018-01-09,Balanced Truncation Model Reduction of a Nonlinear Cable-Mass PDE System with Interior Damping,"We consider model order reduction of a nonlinear cable-mass system modeled by
a 1D wave equation with interior damping and dynamic boundary conditions. The
system is driven by a time dependent forcing input to a linear mass-spring
system at one boundary. The goal of the model reduction is to produce a low
order model that produces an accurate approximation to the displacement and
velocity of the mass in the nonlinear mass-spring system at the opposite
boundary. We first prove that the linearized and nonlinear unforced systems are
well-posed and exponentially stable under certain conditions on the damping
parameters, and then consider a balanced truncation method to generate the
reduced order model (ROM) of the nonlinear input-output system. Little is known
about model reduction of nonlinear input-output systems, and so we present
detailed numerical experiments concerning the performance of the nonlinear ROM.
We find that the ROM is accurate for many different combinations of model
parameters.",1801.02792v1
2018-01-18,Analytic solutions to various dissipation models of the simple and driven quantum harmonic oscillator,"We obtain analytic solutions to various models of dissipation of the quantum
harmonic oscillator, employing a simple method in the Wigner function Fourier
transform description of the system; and study as an exemplification, the
driven open quantum harmonic oscillator. The environmental models we use are
based on optical master equations for the zero and finite temperature bath and
whose open dynamics are described by a Lindblad master equation, and also we
use the Caldeira-Leggett model for the high temperature limit, in the the under
damped an the over damped case. Under the Wigner Fourier transform or chord
function as it has been called, it becomes particularly simple to solve the
dynamics of the open oscillator in the sense that the dynamics of the system
are reduced to the application of an evolution matrix related to the damped
motion of the oscillator.",1801.05943v1
2018-01-23,The effect of liquid on the vibrational intensity of a wineglass at steady state resonance,"As a liquid is inserted into a wineglass, the natural frequency of the
wineglass decreases. This phenomenon, known as pitch lowering, is well
explained in past papers. However, previous literature have not yet mentioned
that pitch lowering also reduces the resonance intensity of a wineglass. Thus,
this present paper aims to extend the body of research on this topic by
describing the relationship between pitch lowering and its effect on resonation
intensity. To do so, we identify the vibrating wineglass wall as a damped
harmonic oscillator, derive a theoretical model, and find that the resonance
intensity of the wineglass is proportional to the square of its natural
frequency, under the assumption that damping stays constant. However, our
experiments showed the coefficient of damping to increase with respect to the
amount of liquid, which caused the data to deviate from its theoretical
predictions. We conclude by discussing the accuracy and limitation of our
proposed model.",1801.07514v5
2018-09-05,On the forced Euler and Navier-Stokes equations: Linear damping and modified scattering,"We study the asymptotic behavior of the forced linear Euler and nonlinear
Navier-Stokes equations close to Couette flow in a periodic channel. As our
main result we show that for smooth time-periodic forcing linear inviscid
damping persists, i.e. the velocity field (weakly) asymptotically converges.
However, stability and scattering to the transport problem fail in $H^{s},
s>-1$. We further show that this behavior is consistent with the nonlinear
Euler equations and that a similar result also holds for the nonlinear
Navier-Stokes equations. Hence, these results provide an indication that
nonlinear inviscid damping may still hold in Sobolev regularity in the above
sense despite the Gevrey regularity instability results of [Deng-Masmoudi
2018].",1809.01729v1
2018-09-12,Theory of bifurcation amplifiers utilizing the nonlinear dynamical response of an optically damped mechanical oscillator,"We consider a standard optomechanical system where a mechanical oscillator is
coupled to a cavity mode through the radiation pressure interaction. The
oscillator is coherently driven at its resonance frequency, whereas the cavity
mode is driven below its resonance, providing optical damping of the mechanical
oscillations. We study the nonlinear coherent response of the mechanical
oscillator in this setup. For large mechanical amplitudes, we find that the
system can display dynamical multistability if the optomechanical cooperativity
exceeds a critical value. This analysis relates standard optomechanical damping
to the dynamical attractors known from the theory of optomechanical
self-sustained oscillations. We also investigate the effect of thermal and
quantum noise and estimate the noise-induced switching rate between the stable
states of the system. We then consider applications of this system and
primarily focus on how it can be used as bifurcation amplifiers for the
detection of small mechanical or optical signals. Finally, we show that in a
related but more complicated setup featuring resonant optomechanical
interactions, the same effects can be realized with a relaxed requirement on
the size of the mechanical oscillations.",1809.04592v2
2018-09-13,Second order asymptotical regularization methods for inverse problems in partial differential equations,"We develop Second Order Asymptotical Regularization (SOAR) methods for
solving inverse source problems in elliptic partial differential equations with
both Dirichlet and Neumann boundary data. We show the convergence results of
SOAR with the fixed damping parameter, as well as with a dynamic damping
parameter, which is a continuous analog of Nesterov's acceleration method.
Moreover, by using Morozov's discrepancy principle together with a newly
developed total energy discrepancy principle, we prove that the approximate
solution of SOAR weakly converges to an exact source function as the
measurement noise goes to zero. A damped symplectic scheme, combined with the
finite element method, is developed for the numerical implementation of SOAR,
which yields a novel iterative regularization scheme for solving inverse source
problems. Several numerical examples are given to show the accuracy and the
acceleration effect of SOAR. A comparison with the state-of-the-art methods is
also provided.",1809.04971v2
2018-09-24,Oscillation Damping Control of Pendulum-like Manipulation Platform using Moving Masses,"This paper presents an approach to damp out the oscillatory motion of the
pendulum-like hanging platform on which a robotic manipulator is mounted. To
this end, moving masses were installed on top of the platform. In this paper,
asymptotic stability of the platform (which implies oscillation damping) is
achieved by designing reference acceleration of the moving masses properly. A
main feature of this work is that we can achieve asymptotic stability of not
only the platform, but also the moving masses, which may be challenging due to
the under-actuation nature. The proposed scheme is validated by the simulation
studies.",1809.08819v1
2018-09-25,"Theory of damping in magnetization dynamics, dispelling a myth and pointing a way forward","There is a widely-held belief amongst theoreticians that the Gilbert damping
parameter {\alpha} in magnetization dynamics is infinite for a pure metal at
T=0. The basic error leading to this belief is pointed out explicitly and the
various methods of calculation used are viewed in a unified way based on the
Lorentzian lineshape of ferromagnetic resonance spectra. A general torque
formula for {\alpha} is proposed as a good starting-point for treating
inhomogeneous materials such as alloys, compounds and layered structures. Local
spin density functional theory provides a simple physical picture, in terms of
a non-uniform precessional cone angle in ferromagnetic resonance, of how such
inhomogeneity contributes to the damping. In a complementary many-body theory
this contribution is given by a vertex correction to the torque-torque response
function.",1809.09429v1
2018-07-16,A unified N-SECE strategy for highly coupled piezoelectric energy scavengers,"This paper proposes a novel vibration energy harvesting strategy based on an
extension of the Synchronous Electric Charge Extraction (SECE) approach,
enabling both the maximization of the harvested power and a consequent
bandwidth enlargement in the case of highly coupled/lightly damped
piezoelectric energy harvesters. The proposed strategy relies on the tuning of
the frequency of the energy extraction events, which is either N times greater
than the vibration frequency (Multiple SECE case, N > 1) or 1/N times smaller
(Regenerative SECE, N < 1). We first prove analytically than increasing or
decreasing N both lead to a damping reduction. While N has no impact on the
system's resonance frequency in the Regenerative case (N < 1), we show that
this resonant frequency becomes a function of N in the Multiple SECE case (N >
1). Experimental results on a highly coupled/lowly damped piezoelectric
harvester (k^2= 0.44, Q_m = 20) demonstrates the potential of this strategy,
leading to 257% harvested power improvement compared to SECE (N = 1). and the
possibility to tune the resonant frequency on a range as large as 35% of the
short-circuit resonant frequency of the harvester.",1809.09685v1
2018-10-09,The lifespan of solutions of semilinear wave equations with the scale-invariant damping in one space dimension,"The critical constant of time-decaying damping in the scale-invariant case is
recently conjectured. It also has been expected that the lifespan estimate is
the same as for the associated semilinear heat equations if the constant is in
the \heat-like"" domain. In this paper, we point out that this is not true if
the total integral of the sum of initial position and speed vanishes. In such a
case, we have a new type of the lifespan estimates which is closely related to
the non-damped case in shifted space dimensions.",1810.03780v2
2018-10-15,Localized spin waves in isolated $kπ$ skyrmions,"The localized magnon modes of isolated $k\pi$ skyrmions on a field-polarized
background are analyzed based on the Landau-Lifshitz-Gilbert equation within
the terms of an atomistic classical spin model, with system parameters based on
the Pd/Fe biatomic layer on Ir(111). For increasing skyrmion order $k$ a higher
number of excitation modes are found, including modes with nodes in the radial
eigenfunctions. It is shown that at low fields $2\pi$ and $3\pi$ skyrmions are
destroyed via a burst instability connected to a breathing mode, while $1\pi$
skyrmions undergo an elliptic instability. At high fields all $k\pi$ skyrmions
collapse due to the instability of a breathing mode. The effective damping
parameters of the spin waves are calculated in the low Gilbert damping limit,
and they are found to diverge in the case of the lowest-lying modes at the
burst and collapse instabilities, but not at the elliptic instability. It is
shown that the breathing modes of $k\pi$ skyrmions may become overdamped at
higher Gilbert damping values.",1810.06471v1
2018-10-24,Nearly isotropic spin-pumping related Gilbert damping in Pt/Ni$_{81}$Fe$_{19}$/Pt,"A recent theory by Chen and Zhang [Phys. Rev. Lett. 114, 126602 (2015)]
predicts strongly anisotropic damping due to interfacial spin-orbit coupling in
ultrathin magnetic films. Interfacial Gilbert-type relaxation, due to the spin
pumping effect, is predicted to be significantly larger for magnetization
oriented parallel to compared with perpendicular to the film plane. Here, we
have measured the anisotropy in the Pt/Ni$_{81}$Fe$_{19}$/Pt system via
variable-frequency, swept-field ferromagnetic resonance (FMR). We find a very
small anisotropy of enhanced Gilbert damping with sign opposite to the
prediction from the Rashba effect at the FM/Pt interface. The results are
contrary to the predicted anisotropy and suggest that a mechanism separate from
Rashba spin-orbit coupling causes the rapid onset of spin-current absorption in
Pt.",1810.10595v4
2018-10-24,Justification of the Lugiato-Lefever model from a damped driven $φ^4$ equation,"The Lugiato-Lefever equation is a damped and driven version of the well-known
nonlinear Schr\""odinger equation. It is a mathematical model describing complex
phenomena in dissipative and nonlinear optical cavities. Within the last two
decades, the equation has gained a wide attention as it becomes the basic model
describing optical frequency combs. Recent works derive the Lugiato-Lefever
equation from a class of damped driven $\phi^4$ equations closed to resonance.
In this paper, we provide a justification of the envelope approximation. From
the analysis point of view, the result is novel and non-trivial as the drive
yields a perturbation term that is not square integrable. The main approach
proposed in this work is to decompose the solutions into a combination of the
background and the integrable component. This paper is the first part of a
two-manuscript series.",1810.10630v1
2019-06-10,Global existence of weak solutions to the compressible quantum Navier-Stokes equations with degenerate viscosity,"We study the compressible quantum Navier-Stokes (QNS) equations with
degenerate viscosity in the three dimensional periodic domains. On the one
hand, we consider QNS with additional damping terms. Motivated by the recent
works [Li-Xin, arXiv:1504.06826] and [Antonelli-Spirito, Arch. Ration. Mech.
Anal., 203(2012), 499--527], we construct a suitable approximate system which
has smooth solutions satisfying the energy inequality and the BD entropy
estimate. Using this system, we obtain the global existence of weak solutions
to the compressible QNS equations with damping terms for large initial data.
Moreover, we obtain some new a priori estimates, which can avoid using the
assumption that the gradient of the velocity is a well-defined function, which
is indeed used directly in [Vasseur-Yu, SIAM J. Math. Anal., 48 (2016),
1489--1511; Invent. Math., 206 (2016), 935--974]. On the other hand, in the
absence of damping terms, we also prove the global existence of weak solutions
to the compressible QNS equations without the lower bound assumption on the
dispersive coefficient, which improves the previous result due to
[Antonelli-Spirito, Arch. Ration. Mech. Anal., 203(2012), 499--527].",1906.03971v1
2019-06-11,Study of semi-linear $σ$-evolution equations with frictional and visco-elastic damping,"In this article, we study semi-linear $\sigma$-evolution equations with
double damping including frictional and visco-elastic damping for any
$\sigma\ge 1$. We are interested in investigating not only higher order
asymptotic expansions of solutions but also diffusion phenomenon in the
$L^p-L^q$ framework, with $1\le p\le q\le \infty$, to the corresponding linear
equations. By assuming additional $L^{m}$ regularity on the initial data, with
$m\in [1,2)$, we prove the global (in time) existence of small data energy
solutions and indicate the large time behavior of the global obtained solutions
as well to semi-linear equations. Moreover, we also determine the so-called
critical exponent when $\sigma$ is integers.",1906.04471v1
2019-07-08,Damping of density oscillations in neutrino-transparent nuclear matter,"We calculate the bulk-viscous dissipation time for adiabatic density
oscillations in nuclear matter at densities of 1-7 times nuclear saturation
density and at temperatures ranging from 1 MeV, where corrections to previous
low-temperature calculations become important, up to 10 MeV, where the
assumption of neutrino transparency is no longer valid. Under these conditions,
which are expected to occur in neutron star mergers, damping of density
oscillations arises from beta equilibration via weak interactions. We find that
for 1 kHz oscillations the shortest dissipation times are in the 5 to 20 ms
range, depending on the equation of state, which means that bulk viscous
damping could affect the dynamics of a neutron star merger. For higher
frequencies the dissipation time can be even shorter.",1907.03795v2
2019-07-12,Decoherence of collective motion in warm nuclei,"Collective states in cold nuclei are represented by a wave function that
assigns coherent phases to the participating nucleons. The degree of coherence
decreases with excitation energy above the yrast line because of coupling to
the increasingly dense background of quasiparticle excitations. The
consequences of decoherence are discussed, starting with the well studied case
of rotational damping. In addition to superdeformed bands, a highly excited
oblate band is presented as a new example of screening from rotational damping.
Suppression of pair correlation leads to incoherent thermal M1 radiation, which
appears as an exponential spike (LEMAR) at zero energy in the $\gamma$ strength
function of spherical nuclei. In deformed nuclei a Scissors Resonance appears
and LEMAR changes to damped magnetic rotation, which is interpreted as partial
restoration of coherence.",1907.05569v1
2019-07-24,First-order optimization algorithms via inertial systems with Hessian driven damping,"In a Hilbert space setting, for convex optimization, we analyze the
convergence rate of a class of first-order algorithms involving inertial
features. They can be interpreted as discrete time versions of inertial
dynamics involving both viscous and Hessian-driven dampings. The geometrical
damping driven by the Hessian intervenes in the dynamics in the form $\nabla^2
f (x(t)) \dot{x} (t)$. By treating this term as the time derivative of $ \nabla
f (x (t)) $, this gives, in discretized form, first-order algorithms in time
and space. In addition to the convergence properties attached to Nesterov-type
accelerated gradient methods, the algorithms thus obtained are new and show a
rapid convergence towards zero of the gradients. On the basis of a
regularization technique using the Moreau envelope, we extend these methods to
non-smooth convex functions with extended real values. The introduction of time
scale factors makes it possible to further accelerate these algorithms. We also
report numerical results on structured problems to support our theoretical
findings.",1907.10536v2
2019-07-26,L^p-asymptotic stability analysis of a 1D wave equation with a nonlinear damping,"This paper is concerned with the asymptotic stability analysis of a one
dimensional wave equation with Dirichlet boundary conditions subject to a
nonlinear distributed damping with an L p functional framework, p $\in$ [2,
$\infty$]. Some well-posedness results are provided together with exponential
decay to zero of trajectories, with an estimation of the decay rate. The
well-posedness results are proved by considering an appropriate functional of
the energy in the desired functional spaces introduced by Haraux in [11].
Asymptotic behavior analysis is based on an attractivity result on a trajectory
of an infinite-dimensional linear time-varying system with a special structure,
which relies on the introduction of a suitable Lyapunov functional. Note that
some of the results of this paper apply for a large class of nonmonotone
dampings.",1907.11712v1
2019-07-27,Two improved Gauss-Seidel projection methods for Landau-Lifshitz-Gilbert equation,"In this paper, we present two improved Gauss-Seidel projection methods with
unconditional stability. The first method updates the gyromagnetic term and the
damping term simultaneously and follows by a projection step. The second method
introduces two sets of approximate solutions, where we update the gyromagnetic
term and the damping term simultaneously for one set of approximate solutions
and apply the projection step to the other set of approximate solutions in an
alternating manner. Compared to the original Gauss-Seidel projection method
which has to solve heat equations $7$ times at each time step, the improved
methods solve heat equations $5$ times and $3$ times, respectively. First-order
accuracy in time and second-order accuracy in space are verified by examples in
both 1D and 3D. In addition, unconditional stability with respect to both the
grid size and the damping parameter is confirmed numerically. Application of
both methods to a realistic material is also presented with hysteresis loops
and magnetization profiles. Compared with the original method, the recorded
running times suggest that savings of both methods are about $2/7$ and $4/7$
for the same accuracy requirement, respectively.",1907.11853v1
2019-09-24,DAMPE Excess from Leptophilic Vector Dark Matter: Model Independent Approach,"We study all extensions of the Standard Model (SM) with a vector dark matter
(VDM) candidate which can explain the peak structure observed by recent DAMPE
experiment in electron-positron cosmic ray spectrum. In this regard, we
consider all leptophilic renormalizable VDM-SM interactions through scalar,
spinor, and vector mediators. We show that only two out of six possible models
could produce DAMPE signal by annihilation of VDM with the mass about 1.5 TeV
in a nearby subhalo whilst simultaneously satisfying constraints from DM relic
density, direct/indirect detection, and the collider bounds. These two models
are the ones with scalar/pseudoscalar mediator $ \phi $ with $ M_{\phi} \in
[1500,3000] $ GeV.",1909.10729v2
2019-09-24,Evaluating the Impacts of Transmission Expansion on Sub-Synchronous Resonance Risk,"While transmission expansions are planned to have positive impact on
reliability of power grids, they could increase the risk and severity of some
of the detrimental incidents in power grid mainly by virtue of changing system
configuration, consequently electrical distance. This paper aims to evaluate
and quantify the impact of transmission expansion projects on Sub-Synchronous
Resonance (SSR) risk through a two-step approach utilizing outage count index
and Sub-synchronous damping index. A graph-theory based SSR screening tool is
introduced to quantify the outage count associated with all grid contingencies
which results in radial connection between renewable generation resources and
nearby series compensated lines. Moreover, a frequency-scan based damping
analysis is performed to assess the impact of transmission expansion on the
system damping in sub-synchronous frequency range. The proposed approach has
been utilized to evaluate the impact of recently-built transmission expansion
project on SSR risk in a portion of Electric Reliability Council of Texas
(ERCOT) grid.",1909.11024v1
2019-10-02,Data-Driven Identification of Rayleigh-Damped Second-Order Systems,"In this paper, we present a data-driven approach to identify second-order
systems, having internal Rayleigh damping. This means that the damping matrix
is given as a linear combination of the mass and stiffness matrices. These
systems typically appear when performing various engineering studies, e.g.,
vibrational and structural analysis. In an experimental setup, the frequency
response of a system can be measured via various approaches, for instance, by
measuring the vibrations using an accelerometer. As a consequence, given
frequency samples, the identification of the underlying system relies on
rational approximation. To that aim, we propose an identification of the
corresponding second-order system, extending the Loewner framework for this
class of systems. The efficiency of the proposed method is demonstrated by
means of various numerical benchmarks.",1910.00838v1
2019-10-06,Deterministic and random attractors for a wave equation with sign changing damping,"The paper gives a detailed study of long-time dynamics generated by weakly
damped wave equations in bounded 3D domains where the damping exponent depends
explicitly on time and may change sign. It is shown that in the case when the
non-linearity is superlinear, the considered equation remains dissipative if
the weighted mean value of the dissipation rate remains positive and that the
conditions of this type are not sufficient in the linear case. Two principally
different cases are considered. In the case when this mean is uniform (which
corresponds to deterministic dissipation rates), it is shown that the
considered system possesses smooth uniform attractors as well as non-autonomous
exponential attractors. In the case where the mean is not uniform (which
corresponds to the random dissipation rate, for instance, when this dissipation
rate is generated by the Bernoulli process), the tempered random attractor is
constructed. In contrast to the usual situation, this random attractor is
expected to have infinite Hausdorff and fractal dimension. The simplified model
example which demonstrates infinite-dimensionality of the random attractor is
also presented.",1910.02430v1
2019-10-23,On the exponential stability of a stratified flow to the 2D IDEAL MHD equations with damping,"We study the stability of a type of stratified flows of the two dimensional
inviscid incompressible MHD equations with velocity damping. The exponential
stability for the perturbation near certain stratified flow is investigated in
a strip-type area R*[0,1]. Although the magnetic filed potential is governed by
a transport equation, by using the algebraic structure of the incompressible
condition, it turns out that the linearized MHD equations around the given
stratified flow retain a non-local damping mechanism. After carefully analyzing
the non-linear structure and introducing some suitable weighted energy norms,
we get the exponential stability by combining the exponential decay in time in
the lower order energy with that in the high order energy.",1910.10598v1
2019-10-24,Wigner instability analysis of the damped Hirota equation,"We address the modulation instability of the Hirota equation in the presence
of stochastic spatial incoherence and linear time-dependent
amplification/attenuation processes via the Wigner function approach. We show
that the modulation instability remains baseband type, though the damping
mechanisms substantially reduce the unstable spectrum independent of the
higher-order contributions (e.g. the higher-order nonlinear interaction and the
third-order dispersion). Additionally, we find out that the unstable structure
due to the Kerr interaction exhibits a significant resilience to the
third-order-dispersion stabilizing effects in comparison with the higher-order
nonlinearity, as well as a moderate Lorentzian spectrum damping may assist the
rising of instability. Finally, we also discuss the relevance of our results in
the context of current experiments exploring extreme wave events driven by the
modulation instability (e.g. the generation of the so-called rogue waves).",1910.11045v2
2020-01-06,A continuous contact force model for impact analysis in multibody dynamics,"A new continuous contact force model for contacting problems with regular or
irregular contacting surfaces and energy dissipations in multibody systems is
presented and discussed in this work. The model is developed according to Hertz
law and a hysteresis damping force is introduced for modeling the energy
dissipation during the contact process. As it is almost impossible to obtain an
analytical solution based on the system dynamic equation, an approximate
dynamic equation for the collision system is proposed, achieving a good
approximation of the system dynamic equation. An approximate function between
deformation velocity and deformation is founded on the approximate dynamic
equation, then it is utilized to calculate the energy loss due to the damping
force. The model is established through modifying the original formula of the
hysteresis damping parameter derived by combining the energy balance and the
law of conservation of linear momentum. Numerical results of five different
continuous contact models reveal the capability of our new model as well as the
effect of the geometry of the contacting surfaces on the dynamic system
response.",2001.01344v1
2020-01-06,Boresight Alignment of DArk Matter Particle Explorer,"The DArk Matter Particle Explorer (DAMPE) can measure $\gamma$-rays in the
energy range from a few GeV to about 10 TeV. The direction of each $\gamma$-ray
is reconstructed with respect to the reference system of the DAMPE payload. In
this paper, we adopt a maximum likelihood method and use the $\gamma$-ray data
centered around several bright point-like sources to measure and correct the
angular deviation from the real celestial coordinate system, the so called
``boresight alignment'' of the DAMPE payload. As a check, we also estimate the
boresight alignment for some sets of simulation data with artificial
orientation and obtain consistent results. The time-dependent boresight
alignment analysis does not show evidence for significant variation of the
parameters.",2001.01804v1
2020-01-09,Nonlinear inviscid damping near monotonic shear flows,"We prove nonlinear asymptotic stability of a large class of monotonic shear
flows among solutions of the 2D Euler equations in the channel
$\mathbb{T}\times[0,1]$. More precisely, we consider shear flows $(b(y),0)$
given by a function $b$ which is Gevrey smooth, strictly increasing, and linear
outside a compact subset of the interval $(0,1)$ (to avoid boundary
contributions which are incompatible with inviscid damping). We also assume
that the associated linearized operator satisfies a suitable spectral
condition, which is needed to prove linear inviscid damping.
  Under these assumptions, we show that if $u$ is a solution which is a small
and Gevrey smooth perturbation of such a shear flow $(b(y),0)$ at time $t=0$,
then the velocity field $u$ converges strongly to a nearby shear flow as the
time goes to infinity. This is the first nonlinear asymptotic stability result
for Euler equations around general steady solutions for which the linearized
flow cannot be explicitly solved.",2001.03087v1
2020-02-03,Semi-active $\mathcal{H}_{\infty}$ damping optimization by adaptive interpolation,"In this work we consider the problem of semi-active damping optimization of
mechanical systems with fixed damper positions. Our goal is to compute a
damping that is locally optimal with respect to the $\mathcal{H}_\infty$-norm
of the transfer function from the exogenous inputs to the performance outputs.
We make use of a new greedy method for computing the $\mathcal{H}_\infty$-norm
of a transfer function based on rational interpolation. In this paper, this
approach is adapted to parameter-dependent transfer functions. The
interpolation leads to parametric reduced-order models that can be optimized
more efficiently. At the optimizers we then take new interpolation points to
refine the reduced-order model and to obtain updated optimizers. In our
numerical examples we show that this approach normally converges fast and thus
can highly accelerate the optimization procedure. Another contribution of this
work are heuristics for choosing initial interpolation points.",2002.00617v1
2020-04-02,A finite element model for seismic response analysis of free-standing rocking columns with vertical dampers,"This paper investigates finite-element modeling of a vertically damped
free-standing rocking column. The paper first derives the nonlinear equation of
motion for the coupled system and then compares the analytical solution with
finite-element model. Finite-element model is being produced using open source
framework named OpenSees. The rocking surface is modeled using zero-length
fiber cross-section element and the dampers are modeled with two node link
elements. In order to simulate energy dissipation during the rocking motion
Hilber-Hughes-Taylor numerical dissipative time step integration is being
adopted. The paper also compares two types of hysteretic and viscous damping
devices and it shows that the viscous damping behavior is favorable when it is
used along with a rocking block. The results of analytical model of a rigid
block with viscous dampers in MATLAB is then compared with OpenSees model and
the paper concludes that the finite-element model compares satisfactory with
the analytical model.",2004.01060v1
2020-04-02,Simulating the effect of weak measurements by a phase damping channel and determining different measures of bipartite correlations in nuclear magnetic resonance,"Quantum discord is a measure based on local projective measurements which
captures quantum correlations that may not be fully captured by entanglement. A
change in the measurement process, achieved by replacing rank-one projectors
with a weak positive operator-valued measure (POVM), allows one to define weak
variants of quantum discord. In this work, we experimentally simulate the
effect of a weak POVM on a nuclear magnetic resonance quantum information
processor. The two-qubit system under investigation is part of a three-qubit
system, where one of the qubits is used as an ancillary to implement the phase
damping channel. The strength of the weak POVM is controlled by varying the
strength of the phase damping channel. We experimentally observed two weak
variants of quantum discord namely, super quantum discord and weak quantum
discord, in two-qubit Werner and Bell-diagonal states. The resultant dynamics
of the states is investigated as a function of the measurement strength.",2004.01237v2
2020-04-24,A rigorous derivation and energetics of a wave equation with fractional damping,"We consider a linear system that consists of a linear wave equation on a
horizontal hypersurface and a parabolic equation in the half space below. The
model describes longitudinal elastic waves in organic monolayers at the
water-air interface, which is an experimental setup that is relevant for
understanding wave propagation in biological membranes. We study the scaling
regime where the relevant horizontal length scale is much larger than the
vertical length scale and provide a rigorous limit leading to a
fractionally-damped wave equation for the membrane. We provide the associated
existence results via linear semigroup theory and show convergence of the
solutions in the scaling limit. Moreover, based on the energy-dissipation
structure for the full model, we derive a natural energy and a natural
dissipation function for the fractionally-damped wave equation with a time
derivative of order 3/2",2004.11830v1
2020-04-25,Pulse-assisted magnetization switching in magnetic nanowires at picosecond and nanosecond timescales with low energy,"Detailed understanding of spin dynamics in magnetic nanomaterials is
necessary for developing ultrafast, low-energy and high-density spintronic
logic and memory. Here, we develop micromagnetic models and analytical
solutions to elucidate the effect of increasing damping and uniaxial anisotropy
on magnetic field pulse-assisted switching time, energy and field requirements
of nanowires with perpendicular magnetic anisotropy and yttrium iron
garnet-like spin transport properties. A nanowire is initially magnetized using
an external magnetic field pulse (write) and self-relaxation. Next, magnetic
moments exhibit deterministic switching upon receiving 2.5 ns-long external
magnetic pulses in both vertical polarities. Favorable damping
({\alpha}~0.1-0.5) and anisotropy energies (10^4-10^5 J m^-3) allow for as low
as picosecond magnetization switching times. Magnetization reversal with fields
below coercivity was observed using spin precession instabilities. A
competition or a nanomagnetic trilemma arises among the switching rate, energy
cost and external field required. Developing magnetic nanowires with optimized
damping and effective anisotropy could reduce the switching energy barrier down
to 3163kBT at room temperature. Thus, pulse-assisted picosecond and low energy
switching in nanomagnets could enable ultrafast nanomagnetic logic and cellular
automata.",2004.12243v1
2020-12-10,Stochastic Damped L-BFGS with Controlled Norm of the Hessian Approximation,"We propose a new stochastic variance-reduced damped L-BFGS algorithm, where
we leverage estimates of bounds on the largest and smallest eigenvalues of the
Hessian approximation to balance its quality and conditioning. Our algorithm,
VARCHEN, draws from previous work that proposed a novel stochastic damped
L-BFGS algorithm called SdLBFGS. We establish almost sure convergence to a
stationary point and a complexity bound. We empirically demonstrate that
VARCHEN is more robust than SdLBFGS-VR and SVRG on a modified DavidNet problem
-- a highly nonconvex and ill-conditioned problem that arises in the context of
deep learning, and their performance is comparable on a logistic regression
problem and a nonconvex support-vector machine problem.",2012.05783v1
2020-12-29,Twist-induced Near-field Thermal Switch Using Nonreciprocal Surface Magnon-Polaritons,"We explore that two ferromagnetic insulator slabs host a strong twist-induced
near-field radiative heat transfer in the presence of twisted magnetic fields.
Using the formalism of fluctuational electrodynamics, we find the existence of
large twist-induced thermal switch ratio in large damping condition and
nonmonotonic twist manipulation for heat transfer in small damping condition,
associated with the different twist-induced effects of nonreciprocal elliptic
surface magnon-polaritons, hyperbolic surface magnon-polaritons, and
twist-non-resonant surface magnon-polaritons. Moreover, the near-field
radiative heat transfer can be significantly enhanced by the twist-non-resonant
surface magnon-polaritons in the ultra-small damping condition. Such
twist-induced effect is applicable for other kinds of anisotropic slabs with
timereversal symmetry breaking. Our findings provide a way to twisted and
magnetic control in nanoscale thermal management and improve it with
twistronics concepts.",2012.14733v1
2021-01-04,The damped harmonic oscillator at the classical limit of the Snyder-de Sitter space,"Valtancoli in his paper entitled [P. Valtancoli, Canonical transformations,
and minimal length J. Math. Phys. 56, 122107 (2015)] has shown how the
deformation of the canonical transformations can be made compatible with the
deformed Poisson brackets. Based on this work and through an appropriate
canonical transformation, we solve the problem of one dimensional (1D) damped
harmonic oscillator at the classical limit of the Snyder-de Sitter (SdS) space.
We show that the equations of the motion can be described by trigonometric
functions with frequency and period depending on the deformed and the damped
parameters. We eventually discuss the influences of these parameters on the
motion of the system.",2101.01223v2
2021-01-11,Damped (linear) response theory within the resolution-of-identity coupled cluster singles and approximate doubles (RI-CC2) method,"An implementation of a complex solver for the solution of the response
equations required to compute the complex response functions of damped response
theory is presented for the resolution-of-identity (RI) coupled-cluster singles
and approximate doubles CC2 method. The implementation uses a partitioned
formulation that avoids the storage of double excitation amplitudes to make it
applicable to large molecules. The solver is the keystone element for the
development of the damped coupled-cluster response formalism for linear and
nonlinear effects in resonant frequency regions at the RI-CC2 level of theory.
Illustrative results are reported for the one-photon absorption cross section
of C60, the electronic circular dichroism of $n$-helicenes ($n$ = 5, 6, 7), and
the $C_6$ dispersion coefficients of a set of selected organic molecules and
fullerenes.",2101.03756v1
2021-01-26,Generalized Damped Newton Algorithms in Nonsmooth Optimization via Second-Order Subdifferentials,"The paper proposes and develops new globally convergent algorithms of the
generalized damped Newton type for solving important classes of nonsmooth
optimization problems. These algorithms are based on the theory and
calculations of second-order subdifferentials of nonsmooth functions with
employing the machinery of second-order variational analysis and generalized
differentiation. First we develop a globally superlinearly convergent damped
Newton-type algorithm for the class of continuously differentiable functions
with Lipschitzian gradients, which are nonsmooth of second order. Then we
design such a globally convergent algorithm to solve a structured class of
nonsmooth quadratic composite problems with extended-real-valued cost
functions, which typically arise in machine learning and statistics. Finally,
we present the results of numerical experiments and compare the performance of
our main algorithm applied to an important class of Lasso problems with those
achieved by other first-order and second-order optimization algorithms.",2101.10555v3
2021-01-26,Damped and Driven Breathers and Metastability,"In this article we prove the existence of a new family of periodic solutions
for discrete, nonlinear Schrodinger equations subject to spatially localized
driving and damping. They provide an alternate description of the metastable
behavior in such lattice systems which agrees with previous predictions for the
evolution of metastable states while providing more accurate approximations to
these states. We analyze the stability of these breathers, finding a very small
positive eigenvalue whose eigenvector lies almost tangent to the surface of the
cylinder formed by the family of breathers. This causes solutions to slide
along the cylinder without leaving its neighborhood for very long times.",2101.10999v2
2012-05-06,Fractional wave equation and damped waves,"In this paper, a fractional generalization of the wave equation that
describes propagation of damped waves is considered. In contrast to the
fractional diffusion-wave equation, the fractional wave equation contains
fractional derivatives of the same order $\alpha,\ 1\le \alpha \le 2$ both in
space and in time. We show that this feature is a decisive factor for
inheriting some crucial characteristics of the wave equation like a constant
propagation velocity of both the maximum of its fundamental solution and its
gravity and mass centers. Moreover, the first, the second, and the Smith
centrovelocities of the damped waves described by the fractional wave equation
are constant and depend just on the equation order $\alpha$. The fundamental
solution of the fractional wave equation is determined and shown to be a
spatial probability density function evolving in time that possesses finite
moments up to the order $\alpha$. To illustrate analytical findings, results of
numerical calculations and numerous plots are presented.",1205.1199v2
2012-05-14,Critical viscoelastic response in jammed solids,"We determine the linear viscoelastic response of jammed packings of athermal
repulsive viscous spheres, a model for emulsions, wet foams, and soft colloidal
suspensions. We numerically measure the complex shear modulus, a fundamental
characterization of the response, and demonstrate that low frequency response
displays dynamic critical scaling near unjamming. Viscoelastic shear response
is governed by the relaxational eigenmodes of a packing. We use scaling
arguments to explain the distribution of eigenrates, which develops a
divergence at unjamming. We then derive the critical exponents characterizing
response, including a vanishing shear modulus, diverging viscosity, and
critical shear thinning regime. Finally, we demonstrate that macroscopic
rheology is sensitive to details of the local viscous force law. By varying the
ratio of normal and tangential damping coefficients, we identify and explain a
qualitative difference between systems with strong and weak damping of sliding
motion. When sliding is weakly damped there is no diverging time scale, no
diverging viscosity, and no critical shear thinning regime.",1205.2960v1
2017-05-10,Negative mobility of a Brownian particle: strong damping regime,"We study impact of inertia on directed transport of a Brownian particle under
non-equilibrium conditions: the particle moves in a one-dimensional periodic
and symmetric potential, is driven by both an unbiased time-periodic force and
a constant force, and is coupled to a thermostat of temperature T. Within
selected parameter regimes this system exhibits negative mobility, which means
that the particle moves in the direction opposite to the direction of the
constant force. It is known that in such a setup the inertial term is essential
for the emergence of negative mobility and it cannot be detected in the
limiting case of overdamped dynamics. We analyse inertial effects and show that
negative mobility can be observed even in the strong damping regime. We
determine the optimal dimensionless mass for the presence of negative mobility
and reveal three mechanisms standing behind this anomaly: deterministic
chaotic, thermal noise induced and deterministic non-chaotic. The last origin
has never been reported. It may provide guidance to the possibility of
observation of negative mobility for strongly damped dynamics which is of
fundamental importance from the point of view of biological systems, all of
which in situ operate in fluctuating environments.",1705.03661v1
2017-05-27,Power System Supplementary Damping Controllers in the Presence of Saturation,"This paper presents the analysis and a method to design supplementary damping
controllers (SDCs) for synchronous generators considering the effects of
saturation limits. Usually such saturations of control signals are imposed in
order to enforce practical limitations such as component ratings. However, to
guarantee the stability in the presence of saturation limits, the state
trajectories must remain inside the domain of attraction (DA). In this paper,
the domain of attraction of a single-machine infinite-bus (SMIB) power system
with saturation nonlinearity is estimated and compared with the exact
description of the null controllable region. Then, state-feedback controllers
are designed to enlarge the DA. Our analysis shows that nonlinear effects of
saturation should be considered to guarantee stability and satisfactory
performance. Simulation results on a detailed nonlinear model of a synchronous
generator indicate that the DA enlarges with the proposed controller. The
results also indicate that Critical Clearing Time (CCT) and damping of the
system with saturation can be improved by the proposed method.",1705.09849v1
2017-05-26,Absence of Landau damping in driven three-component Bose-Einstein condensate in optical lattices,"We explore the quantum many-body physics of a three-component Bose-Einstein
condensate (BEC) in an optical lattices driven by laser fields in $V$ and
$\Lambda$ configurations. We obtain exact analytical expressions for the energy
spectrum and amplitudes of elementary excitations, and discover symmetries
among them. We demonstrate that the applied laser fields induce a gap in the
otherwise gapless Bogoliubov spectrum. We find that Landau damping of the
collective modes above the energy of the gap is carried by laser-induced roton
modes and is considerably suppressed compared to the phonon-mediated damping
endemic to undriven scalar BECs.",1705.10199v2
2017-05-31,Low-energy modes of spin-imbalanced Fermi gases in BCS phase,"The low-energy modes of a spin-imbalanced superfluid Fermi gas in the
Bardeen-Cooper-Schrieffer (BCS) side are studied. The gas is assumed to be
sufficiently dilute so that the pairing of atoms can be considered effective
only in s-wave between fermions of different internal state. The order
parameter at equilibrium is determined by the mean-field approximation, while
the properties of the collective modes are calculated within a Gaussian
approximation for the fluctuations of the order parameter. In particular we
investigate the effects of asymmetry between the populations of the two
different components and of temperature on the frequency and damping of
collective modes. It is found that the temperature does not much affect the
frequency and the damping of the modes, whereas an increase of the imbalance
shifts the frequency toward lower values and enhances the damping sensitively.
Besides the Bogoliubov-Anderson phonons, we observe modes at zero frequency for
finite values of the wave-number. These modes indicate that an instability
develops driving the system toward two separate phases, normal and superfluid.",1705.11162v1
2017-09-06,Linear gyrokinetic investigation of the geodesic acoustic modes in realistic tokamak configurations,"Geodesic acoustic modes (GAMs) are studied by means of the gyrokinetic global
particle-in-cell code ORB5. Linear electromagnetic simulations in the low
electron beta limit have been performed, in order to separate acoustic and
Alfv\'enic time scales and obtain more accurate measurements. The dependence of
the frequency and damping rate on several parameters such as the safety factor,
the GAM radial wavenumber and the plasma elongation is studied. All simulations
have been performed with kinetic electrons with realistic electron/ion mass
ratio. Interpolating formulae for the GAM frequency and damping rate, based on
the results of the gyrokinetic simulations, have been derived. Using these
expressions, the influence of the temperature gradient on the damping rate is
also investigated. Finally, the results are applied to the study of a real
discharge of the ASDEX Upgrade tokamak.",1709.01818v1
2017-09-17,Further insights into the damping-induced self-recovery phenomenon,"In a series of papers, D. E. Chang, et al., proved and experimentally
demonstrated a phenomenon they termed ""damping-induced self-recovery"". However,
these papers left a few questions concerning the observed phenomenon unanswered
- in particular, the effect of the intervening lubricant-fluid and its
viscosity on the recovery, the abrupt change in behaviour with the introduction
of damping, a description of the energy dynamics, and the curious occurrence of
overshoots and oscillations and its dependence on the control law. In this
paper we attempt to answer these questions through theory. In particular, we
derive an expression for the infinite-dimensional fluid-stool-wheel system,
that approximates its dynamics to that of the better understood
finite-dimensional case.",1709.05596v5
2017-09-19,An Improved Primal-Dual Interior Point Solver for Model Predictive Control,"We propose a primal-dual interior-point (PDIP) method for solving quadratic
programming problems with linear inequality constraints that typically arise
form MPC applications. We show that the solver converges (locally)
quadratically to a suboptimal solution of the MPC problem. PDIP solvers rely on
two phases: the damped and the pure Newton phases. Compared to state-of-the-art
PDIP methods, our solver replaces the initial damped Newton phase (usually used
to compute a medium-accuracy solution) with a dual solver based on Nesterov's
fast gradient scheme (DFG) that converges with a sublinear convergence rate of
order O(1/k^2) to a medium-accuracy solution. The switching strategy to the
pure Newton phase, compared to the state of the art, is computed in the dual
space to exploit the dual information provided by the DFG in the first phase.
Removing the damped Newton phase has the additional advantage that our solver
saves the computational effort required by backtracking line search. The
effectiveness of the proposed solver is demonstrated on a 2-dimensional
discrete-time unstable system and on an aerospace application.",1709.06362v1
2017-09-22,Nonlinear stage of Benjamin-Feir instability in forced/damped deep water waves,"We study a three-wave truncation of a recently proposed damped/forced
high-order nonlinear Schr\""odinger equation for deep-water gravity waves under
the effect of wind and viscosity. The evolution of the norm (wave-action) and
spectral mean of the full model are well captured by the reduced dynamics.
Three regimes are found for the wind-viscosity balance: we classify them
according to the attractor in the phase-plane of the truncated system and to
the shift of the spectral mean. A downshift can coexist with both net forcing
and damping, i.e., attraction to period-1 or period-2 solutions. Upshift is
associated with stronger winds, i.e., to a net forcing where the attractor is
always a period-1 solution. The applicability of our classification to
experiments in long wave-tanks is verified.",1709.07850v2
2017-09-27,On long-time asymptotics for viscous hydrodynamic models of collective behavior with damping and nonlocal interactions,"Hydrodynamic systems arising in swarming modelling include nonlocal forces in
the form of attractive-repulsive potentials as well as pressure terms modelling
strong local repulsion. We focus on the case where there is a balance between
nonlocal attraction and local pressure in presence of confinement in the whole
space. Under suitable assumptions on the potentials and the pressure functions,
we show the global existence of weak solutions for the hydrodynamic model with
viscosity and linear damping. By introducing linear damping in the system, we
ensure the existence and uniqueness of stationary solutions with compactly
supported density, fixed mass and center of mass. The associated velocity field
is zero in the support of the density. Moreover, we show that global weak
solutions converge for large times to the set of these stationary solutions in
a suitable sense. In particular cases, we can identify the limiting density
uniquely as the global minimizer of the free energy with the right mass and
center of mass.",1709.09290v2
2017-09-28,Landau Damping with Electron Lenses in Space-Charge Dominated Beams,"Progress on the Intensity Frontier of high energy physics critically depends
on record high intensity charged particles accelerators. Beams in such machines
become operationally limited by coherent beam instabilities, particularly
enhanced in the regime of strong space charge (SC). Usual methods to control
the instabilities, such as octupole magnets, beam feedback dampers and
employment of chromatic effects, become less effective and insufficient. In [1]
it was proposed to employ electron lenses for introduction of sufficient spread
in particle oscillation frequencies needed for beam stabilization and in [2] it
was shown that electron lenses are uniquely effective for Landau damping of
transverse beam instabilities in high energy particle accelerators and their
employment does not compromise incoherent (single particle) stability, dynamic
aperture and the beam lifetime. Here we consider an important issue of
effectiveness of the Landau damping with electron lenses in space-charge
dominated beams and demonstrate that the desired stability can be assured with
proper choice of the electron beam parameters and current distributions.",1709.10020v1
2017-11-01,Tunable magnetization relaxation of Fe_{2}Cr_{1-x}Co_{x}Si half-metallic Heusler alloys by band structure engineering,"We report a systematic investigation on the magnetization relaxation
properties of iron-based half-metallic Heusler alloy
Fe$_{2}$Cr$_{1-x}$Co_${x}$Si (FCCS) thin films using broadband angular-resolved
ferromagnetic resonance. Band structure engineering through Co doping (x)
demonstrated by first-principles calculations is shown to tune the intrinsic
magnetic damping over an order of magnitude, namely 0.01-0.0008. Notably, the
intrinsic damping constants for samples with high Co concentration are among
the lowest reported for Heusler alloys and even comparable to magnetic
insulator yttrium iron garnet. Furthermore, a significant reduction of both
isotropic and anisotropic contributions of extrinsic damping of the FCCS alloys
was found in the FCCS films with x=0.5-0.75, which is of particular importance
for applications. These results demonstrate a practical recipe to tailor
functional magnetization for Heusler alloy-based spintronics at room
temperature",1711.00406v1
2017-11-08,Bulk viscous corrections to screening and damping in the deconfined phase at high temperature,"Non-equilibrium corrections in a hot QCD medium modify the ""hard thermal
loops"" (HTL) which determine the resummed propagators for gluons with soft
momenta as well as the Debye screening and Landau damping mass scales. We focus
on bulk viscous corrections to a thermal fixed point. The screening and damping
mass scales are sensitive to the bulk pressure and perhaps to (pseudo-)
critical dynamical scaling of the bulk viscosity in the vicinity of a
second-order critical point. This would affect the properties of quarkonium
bound states in the deconfined phase.",1711.03072v1
2017-11-29,A model explaining neutrino masses and the DAMPE cosmic ray electron excess,"We propose a flavored $U(1)_{e\mu}$ neutrino mass and dark matter~(DM) model
to explain the recent DArk Matter Particle Explorer (DAMPE) data, which feature
an excess on the cosmic ray electron plus positron flux around 1.4 TeV. Only
the first two lepton generations of the Standard Model are charged under the
new $U(1)_{e\mu}$ gauge symmetry. A vector-like fermion $\psi$, which is our DM
candidate, annihilates into $e^{\pm}$ and $\mu^{\pm}$ via the new gauge boson
$Z'$ exchange and accounts for the DAMPE excess. We have found that the data
favors a $\psi$ mass around 1.5~TeV and a $Z'$ mass around 2.6~TeV, which can
potentially be probed by the next generation lepton colliders and DM direct
detection experiments.",1711.10995v2
2017-11-29,Electrophilic dark matter with dark photon: from DAMPE to direct detection,"The electron-positron excess reported by the DAMPE collaboration recently may
be explained by an electrophilic dark matter (DM). A standard model singlet
fermion may play the role of such a DM when it is stablized by some symmetries,
such as a dark $U(1)_X^{}$ gauge symmetry, and dominantly annihilates into the
electron-positron pairs through the exchange of a scalar mediator. The model,
with appropriate Yukawa couplings, can well interpret the DAMPE excess. Naively
one expects that in this type of models the DM-nucleon cross section should be
small since there is no tree-level DM-quark interactions. We however find that
at one-loop level, a testable DM-nucleon cross section can be induced for
providing ways to test the electrophilic model. We also find that a $U(1)$
kinetic mixing can generate a sizable DM-nucleon cross section although the
$U(1)_X^{}$ dark photon only has a negligible contribution to the DM
annihilation. Depending on the signs of the mixing parameter, the dark photon
can enhance/reduce the one-loop induced DM-nucleon cross section.",1711.11000v2
2017-11-30,Leptophilic dark matter in gauged $U(1)_{L_e-L_μ}$ model in light of DAMPE cosmic ray $e^+ + e^-$ excess,"Motivated by the very recent cosmic-ray electron+positron excess observed by
DAMPE collaboration, we investigate a Dirac fermion dark matter (DM) in the
gauged $L_e - L_\mu$ model. DM interacts with the electron and muon via the
$U(1)_{e-\mu}$ gauge boson $Z^{'}$. The model can explain the DAMPE data well.
Although a non-zero DM-nucleon cross section is only generated at one loop
level and there is a partial cancellation between $Z^{'}ee$ and $Z^{'}\mu\mu$
couplings, we find that a large portion of $Z^{'}$ mass is ruled out from
direct DM detection limit leaving the allowed $Z^{'}$ mass to be close to two
times of the DM mass. Implications for $pp \to Z^{'} \to 2\ell$ and $pp \to
2\ell + Z^{'}$ , and muon $g-2$ anomaly are also studied.",1711.11563v3
2018-03-07,Connecting dissipation and noncommutativity: A Bateman system case study,"Quantum effects on a pair of Bateman oscillators embedded in an ambient
noncommutative space (Moyal plane) is analyzed using both path integral and
canonical quantization schemes within the framework of Hilbert-Schmidt operator
formulation. We adopt a method which is distinct from the one which employs 't
Hooft's scheme of quantization, carried out earlier in the literature where the
ambient space was taken to be commutative. Our quantization shows that we end
up finally again with a Bateman system except that the damping factor undergoes
renormalization. The corresponding expression shows that the renormalized
damping factor can be non-zero even if ""bare"" one is zero to begin with.
Conversely, the noncommuatative parameter $\theta$, taken to be a free one now,
can be fine-tuned to get a vanishing renormalized damping factor. This
indicates a duality between dissipative commutative theory and non-dissipative
noncommutative theory.",1803.03334v1
2018-03-18,A machine learning method to separate cosmic ray electrons from protons from 10 to 100 GeV using DAMPE data,"DArk Matter Particle Explorer (DAMPE) is a general purpose high energy cosmic
ray and gamma ray observatory, aiming to detect high energy electrons and
gammas in the energy range 5 GeV to 10 TeV and hundreds of TeV for nuclei. This
paper provides a method using machine learning to identify electrons and
separate them from gammas,protons,helium and heavy nuclei with the DAMPE data
from 2016 January 1 to 2017 June 30, in energy range from 10 to 100 GeV.",1803.06628v2
2018-03-20,Estimating Participation Factors and Mode Shapes for Electromechanical Oscillations in Ambient Conditions,"In this paper, a new technique is applied to conduct mode identification
using ambient measurement data. The proposed hybrid measurement- and
model-based method can accurately estimate the system state matrix in ambient
conditions, the eigenvalues and eigenvectors of which readily provide all the
modal knowledge including frequencies, damping ratios, mode shapes, and more
importantly, participation factors. Numerical simulations show that the
proposed technique is able to provide accurate estimation of modal knowledge
for all modes. In addition, the discrepancy between the participation factor
and the mode shape is shown through a numerical example, demonstrating that
using the mode shape may not effectively pinpoint the best location for damping
control. Therefore, the proposed technique capable of estimating participation
factors may greatly facilitate designing damping controls.",1803.07264v1
2018-03-21,Globally Stable Output Feedback Synchronization of Teleoperation with Time-Varying Delays,"This paper presents a globally stable teleoperation control strategy for
systems with time-varying delays that eliminates the need for velocity
measurements through novel augmented Immersion and Invariance velocity
observers. The new observers simplify a recent constructive Immersion and
Invariance velocity observer to achieve globally convergent velocity estimation
with only $n+2$ states, where $n$ is the number of degrees of freedom of the
master and slave robots. They introduce dynamic scaling factors to accelerate
the speed of convergence of the velocity estimates and, thus, to limit the
energy generated by the velocity estimation errors and to guarantee sufficient
estimate-based damping injection to dissipate the energy generated by the
time-varying delays. The paper shows that Proportional plus damping control
with the simplified and augmented Immersion and Invariance-based velocity
observers can synchronize the free master and slave motions in the presence of
time-varying delays without using velocity measurements. Numerical results
illustrate the estimation performance of the new observers and the stability of
a simulated two degrees-of-freedom nonlinear teleoperation system with
time-varying delays under the proposed output feedback Proportional plus
damping control.",1803.08159v1
2018-03-29,Stochastic conformal multi-symplectic method for damped stochastic nonlinear Schrodinger equation,"In this paper, we propose a stochastic conformal multi-symplectic method for
a class of damped stochastic Hamiltonian partial differential equations in
order to inherit the intrinsic properties, and apply the numerical method to
solve a kind of damped stochastic nonlinear Schrodinger equation with
multiplicative noise. It is shown that the stochastic conformal
multi-symplectic method preserves the discrete stochastic conformal
multi-symplectic conservation law, the discrete charge exponential dissipation
law almost surely, and we also deduce the recurrence relation of the discrete
global energy. Numerical experiments are preformed to verify the good
performance of the proposed stochastic conformal multi-symplectic method,
compared with a Crank-Nicolson type method. Finally, we present the mean square
convergence result of the proposed numerical method in temporal direction
numerically.",1803.10885v1
2018-06-18,Theoretical interpretations of DAMPE first results: a critical review,"The DAMPE experiment recently published its first results on the lepton ($e^+
+ e^-$) cosmic-ray (CRs) flux. These results are of importance since they
account for the first direct detection of the lepton break around the energy of
1 TeV and confirm the discoveries of ground-based Cherenkov detectors.
Meanwhile they reveal a new high-energy feature in the spectrum which triggered
a lot of excitement on the theory side, when interpreted as the typical
signature of leptophilic dark-matter annihilation. In this proceeding I mainly
focus on the theoretical understanding of the lepton break. Then I quickly
review the status of the more speculative line-like DAMPE excess, whose
astrophysical (pulsar) or exotic (dark matter) explanation is strongly
constrained by multi-messenger astronomy.",1806.06534v1
2018-06-22,Optimal Design of Virtual Inertia and Damping Coefficients for Virtual Synchronous Machines,"Increased penetration of inverter-connected renewable energy sources (RES) in
the power system has resulted in a decrease in available rotational inertia
which serves as an immediate response to frequency deviation due to
disturbances. The concept of virtual inertia has been proposed to combat this
decrease by enabling the inverters to produce active power in response to a
frequency deviation like a synchronous generator. In this paper, we present an
algorithm to optimally design the inertia and damping coefficient required for
an inverter-based virtual synchronous machine (VSM) to participate efficiently
in the inertia response portion of primary frequency control. We design the
objective function to explicitly trade-off between competing objectives such as
the damping rate the the frequency nadir. Specifically, we formulate the design
problem as a constrained and regularized H2 norm minimization problem, and
develop an efficient gradient algorithm for this non-convex problem. This
proposed algorithm is applied to a test case to demonstrate its performance
against existing methods.",1806.08488v1
2018-07-17,Bipartite and Tripartite Entanglement for Three Damped Driven Qubits,"We investigate bipartite and tripartite entanglement in an open quantum
system, specifically three qubits, all of which are damped, and one of which is
driven. We adapt a systematic approach in calculating the entanglement of
various bipartite splits usinga generalized concurrence as an indicator of
entanglement. Our calculations are based on a direct detection scheme that is a
particular unravelling of the density matrix. This system has a collective
dipole-dipole energy shift that couples the atoms and the dissipation is via
partially collective spontaneous emission described by the Lehmberg-Agarwal
master equation.Our results are unravelling dependent, but apply to
applications of entanglement based on direct detection. We also calculate the
three-way tangle or residual entanglement for this system. We present
calculations for a variety of driving and damping rates, and examine what decay
rate is adequate for the system to be reduced to two qubits with a readout
port. We also consider a specific model of three atoms located at particular
positions in free space.",1807.06178v1
2018-07-17,Boundary-to-Displacement Asymptotic Gains for Wave Systems With Kelvin-Voigt Damping,"We provide estimates for the asymptotic gains of the displacement of a
vibrating string with endpoint forcing, modeled by the wave equation with
Kelvin-Voigt and viscous damping and a boundary disturbance. Two asymptotic
gains are studied: the gain in the L2 spatial norm and the gain in the spatial
sup norm. It is shown that the asymptotic gain property holds in the L2 norm of
the displacement without any assumption for the damping coefficients. The
derivation of the upper bounds for the asymptotic gains is performed by either
employing an eigenfunction expansion methodology or by means of a small-gain
argument, whereas a novel frequency analysis methodology is employed for the
derivation of the lower bounds for the asymptotic gains. The graphical
illustration of the upper and lower bounds for the gains shows that that the
asymptotic gain in the L2 norm is estimated much more accurately than the
asymptotic gain in the sup norm.",1807.06549v1
2018-07-24,Stabilization of an unstable wave equation using an infinite dimensional dynamic controller,"This paper deals with the stabilization of an anti-stable string equation
with Dirichlet actuation where the instability appears because of the
uncontrolled boundary condition. Then, infinitely many unstable poles are
generated and an infinite dimensional control law is therefore proposed to
exponentially stabilize the system. The idea behind the choice of the
controller is to extend the domain of the PDE so that the anti-damping term is
compensated by a damping at the other boundary condition. Additionally, notice
that the system can then be exponentially stabilized with a chosen decay-rate
and is robust to uncertainties on the wave speed and the anti-damped
coefficient of the wave equation, with the only use of a point-wise boundary
measurement. The efficiency of this new control strategy is then compared to
the backstepping approach.",1807.08999v2
2018-07-24,Interplay between intermittency and dissipation in collisionless plasma turbulence,"We study the damping of collisionless Alfv\'enic turbulence by two
mechanisms: stochastic heating (whose efficiency depends on the local
turbulence amplitude $\delta z_\lambda$) and linear Landau damping (whose
efficiency is independent of $\delta z_\lambda$), describing in detail how they
affect and are affected by intermittency. The overall efficiency of linear
Landau damping is not affected by intermittency in critically balanced
turbulence, while stochastic heating is much more efficient in the presence of
intermittent turbulence. Moreover, stochastic heating leads to a drop in the
scale-dependent kurtosis over a narrow range of scales around the ion
gyroscale.",1807.09301v2
2018-07-31,Input-to-State Stability of a Clamped-Free Damped String in the Presence of Distributed and Boundary Disturbances,"This note establishes the Exponential Input-to-State Stability (EISS)
property for a clamped-free damped string with respect to distributed and
boundary disturbances. While efficient methods for establishing ISS properties
for distributed parameter systems with respect to distributed disturbances have
been developed during the last decades, establishing ISS properties with
respect to boundary disturbances remains challenging. One of the well-known
methods for well-posedness analysis of systems with boundary inputs is the use
of a lifting operator for transferring the boundary disturbance to a
distributed one. However, the resulting distributed disturbance involves time
derivatives of the boundary perturbation. Thus, the subsequent ISS estimate
depends on its amplitude, and may not be expressed in the strict form of ISS
properties. To solve this problem, we show for a clamped-free damped string
equation that the projection of the original system trajectories in an adequate
Riesz basis can be used to establish the desired EISS property.",1807.11696v2
2018-07-31,Spin absorption at ferromagnetic-metal/platinum-oxide interface,"We investigate the absorption of a spin current at a
ferromagnetic-metal/Pt-oxide interface by measuring current-induced
ferromagnetic resonance. The spin absorption was characterized by the magnetic
damping of the heterostructure. We show that the magnetic damping of a
Ni$_{81}$Fe$_{19}$ film is clearly enhanced by attaching Pt-oxide on the
Ni$_{81}$Fe$_{19}$ film. The damping enhancement is disappeared by inserting an
ultrathin Cu layer between the Ni$_{81}$Fe$_{19}$ and Pt-oxide layers. These
results demonstrate an essential role of the direct contact between the
Ni$_{81}$Fe$_{19}$ and Pt-oxide to induce sizable interface spin-orbit
coupling. Furthermore, the spin-absorption parameter of the
Ni$_{81}$Fe$_{19}$/Pt-oxide interface is comparable to that of intensively
studied heterostructures with strong spin-orbit coupling, such as an oxide
interface, topological insulators, metallic junctions with Rashba spin-orbit
coupling. This result illustrates strong spin-orbit coupling at the
ferromagnetic-metal/Pt-oxide interface, providing an important piece of
information for quantitative understanding the spin absorption and spin-charge
conversion at the ferromagnetic-metal/metallic-oxide interface.",1807.11806v1
2018-08-16,Stability analysis of dissipative systems subject to nonlinear damping via Lyapunov techniques,"In this article, we provide a general strategy based on Lyapunov functionals
to analyse global asymptotic stability of linear infinite-dimensional systems
subject to nonlinear dampings under the assumption that the origin of the
system is globally asymp-totically stable with a linear damping. To do so, we
first characterize, in terms of Lyapunov functionals, several types of
asymptotic stability for linear infinite-dimensional systems, namely the
exponential and the polynomial stability. Then, we derive a Lyapunov functional
for the nonlinear system, which is the sum of a Lyapunov functional coming from
the linear system and another term with compensates the nonlinearity. Our
results are then applied to the linearized Korteweg-de Vries equation and some
wave equations.",1808.05370v1
2018-08-30,The influence of the coefficients of a system of coupled wave equations with fractional damping on its stabilization,"In this work, we consider a system of two wave equations coupled by
velocities in one-dimensional space, with one boundary fractional damping.
First, we show that the system is strongly asymptotically stable if and only if
the coupling parameter b of the two equations is outside a discrete set of
exceptional real values. Next, we show that our system is not uniformly stable.
Hence, we look for a polynomial decay rate for smooth initial data. Using
frequency domain approach combining with multiplier method, we prove that the
energy decay rate is greatly influenced by the nature of the coupling parameter
b, the arithmetic property of the ratio of the wave propagation speeds a, the
order of the fractional damping. Indeed, under the equal speed propagation
condition, we establish an optimal polynomial energy decay rate. Furthermore,
when the wave propagate with different speeds, under some arithmetic conditions
on the ratio of the wave propagation speeds, we prove that the energy of our
system decays polynomially to zero.",1808.10285v4
2018-12-06,Damping and Anti-Damping Phenomena in Metallic Antiferromagnets: An ab-initio Study,"We report on a first principles study of anti-ferromagnetic resonance (AFMR)
phenomena in metallic systems [MnX (X=Ir,Pt,Pd,Rh) and FeRh] under an external
electric field. We demonstrate that the AFMR linewidth can be separated into a
relativistic component originating from the angular momentum transfer between
the collinear AFM subsystem and the crystal through the spin orbit coupling
(SOC), and an exchange component that originates from the spin exchange between
the two sublattices. The calculations reveal that the latter component becomes
significant in the low temperature regime. Furthermore, we present results for
the current-induced intersublattice torque which can be separated into the
Field-Like (FL) and Damping-Like (DL) components, affecting the intersublattice
exchange coupling and AFMR linewidth, respectively.",1812.02844v2
2018-12-12,Extreme wave events for a nonlinear Schrödinger equation with linear damping and Gaussian driving,"We perform a numerical study of the initial-boundary value problem, with
vanishing boundary conditions, of a driven nonlinear Schr\""odinger equation
(NLS) with linear damping and a Gaussian driver. We identify Peregrine-like
rogue waveforms, excited by two different types of vanishing initial data
decaying at an algebraic or exponential rate. The observed extreme events
emerge on top of a decaying support. Depending on the spatial/temporal scales
of the driver, the transient dynamics -- prior to the eventual decay of the
solutions -- may resemble the one in the semiclassical limit of the integrable
NLS, or may, e.g., lead to large-amplitude breather-like patterns. The effects
of the damping strength and driving amplitude, in suppressing or enhancing
respectively the relevant features, as well as of the phase of the driver in
the construction of a diverse array of spatiotemporal patterns, are numerically
analyzed.",1812.05439v3
2018-12-13,Stability of elastic transmission systems with a local Kelvin-Voigt damping,"In this paper, we consider the longitudinal and transversal vibrations of the
transmission Euler-Bernoulli beam with Kelvin-Voigt damping distributed locally
on any subinterval of the region occupied by the beam and only in one side of
the transmission point. We prove that the semigroup associated with the
equation for the transversal motion of the beam is exponentially stable,
although the semigroup associated with the equation for the longitudinal motion
of the beam is polynomially stable. Due to the locally distributed and
unbounded nature of the damping, we use a frequency domain method and combine a
contradiction argument with the multiplier technique to carry out a special
analysis for the resolvent.",1812.05923v1
2018-12-13,Energy decay estimates of elastic transmission wave/beam systems with a local Kelvin-Voigt damping,"We consider a beam and a wave equations coupled on an elastic beam through
transmission conditions. The damping which is locally distributed acts through
one of the two equations only; its effect is transmitted to the other equation
through the coupling. First we consider the case where the dissipation acts
through the beam equation. Using a recent result of Borichev and Tomilov on
polynomial decay characterization of bounded semigroups we provide a precise
decay estimates showing that the energy of this coupled system decays
polynomially as the time variable goes to infinity. Second, we discuss the case
where the damping acts through the wave equation. Proceeding as in the first
case, we prove that this system is also polynomially stable and we provide
precise polynomial decay estimates for its energy. Finally, we show the lack of
uniform exponential decay of solutions for both models.",1812.05924v1
2018-12-20,Sound attenuation in stable glasses,"Understanding the difference between universal low-temperature properties of
amorphous and crystalline solids requires an explanation of the stronger
damping of long-wavelength phonons in amorphous solids. A longstanding sound
attenuation scenario, resulting from a combination of experiments, theories,
and simulations, leads to a quartic scaling of sound attenuation with the
wavevector, which is commonly attributed to Rayleigh scattering of the sound.
Modern computer simulations offer conflicting conclusions regarding the
validity of this picture. We simulate glasses with an unprecedentedly broad
range of stabilities to perform the first microscopic analysis of sound damping
in model glass formers across a range of experimentally relevant preparation
protocols. We present a convincing evidence that quartic scaling is recovered
for small wavevectors irrespective of the glass's stability. With increasing
stability, the wavevector where the quartic scaling begins increases by
approximately a factor of three and the sound attenuation decreases by over an
order of magnitude. Our results uncover an intimate connection between glass
stability and sound damping.",1812.08736v2
2018-12-21,"Reply to the Comment on ""Negative Landau damping in bilayer graphene""","Here we address the concerns of Svintsov and Ryzhii [arXiv:1812.03764] on our
article on negative Landau damping in graphene [Phys. Rev. Lett. 119, 133901
(2017)]. We prove that due to the differences between the kinetic and canonical
momenta, the conductivity of drift-current biased graphene is ruled by a
Galilean transformation when the electron-electron interactions predominate and
force the electron gas to move with constant velocity, similar to a moving
medium. Furthermore, it is shown that the nonlocal effects in graphene neither
preclude a negative Landau damping nor the emergence of instabilities in
graphene platforms.",1812.09103v3
2018-12-27,Nonexistence of global solutions for a weakly coupled system of semilinear damped wave equations of derivative type in the scattering case,"In this paper we consider the blow-up for solutions to a weakly coupled
system of semilinear damped wave equations of derivative type in the scattering
case. After introducing suitable functionals proposed by Lai-Takamura for the
corresponding single semilinear equation, we employ Kato's lemma to derive the
blow-up result in the subcritical case. On the other hand, in the critical case
an iteration procedure based on the slicing method is employed. Let us point
out that we find as critical curve in the p-q plane for the pair of exponents
(p, q) in the nonlinear terms the same one as for the weakly coupled system of
semilinear not-damped wave equations with the same kind of nonlinearities.",1812.10653v1
2018-12-30,"Smooth, Time-invariant Regulation of Nonholonomic Systems via Energy Pumping-and-Damping","In this paper we propose an energy pumping-and-damping technique to regulate
nonholonomic systems described by kinematic models. The controller design
follows the widely popular interconnection and damping assignment
passivity-based methodology, with the free matrices partially structured. Two
asymptotic regulation objectives are considered: drive to zero the state or
drive the systems total energy to a desired constant value. In both cases, the
control laws are smooth, time-invariant, state-feedbacks. For the nonholonomic
integrator we give an almost global solution for both problems, with the
objectives ensured for all system initial conditions starting outside a set
that has zero Lebesgue measure and is nowhere dense. For the general case of
higher-order nonholonomic systems in chained form, a local stability result is
given. Simulation results comparing the performance of the proposed controller
with other existing designs are also provided.",1812.11538v2
2019-01-05,Simulations of wobble damping in viscoelastic rotators,"Using a damped mass-spring model, we simulate wobble of spinning homogeneous
viscoelastic ellipsoids undergoing non-principal axis rotation. Energy damping
rates are measured for oblate and prolate bodies with different spin rates,
spin states, viscoelastic relaxation timescales, axis ratios, and strengths.
Analytical models using a quality factor by Breiter et al. (2012) and for the
Maxwell rheology by Frouard & Efroimsky (2018) match our numerical measurements
of the energy dissipation rate after we modify their predictions for the
numerically simulated Kelvin-Voigt rheology. Simulations of nearly spherical
but wobbling bodies with hard and soft cores show that the energy dissipation
rate is more sensitive to the material properties in the core than near the
surface. The sensitivity to viscoelastic model implies that inferred statistics
of tumbling lifetimes in asteroids might be interpreted in terms of differences
in their material properties.",1901.01439v3
2019-01-16,"Laboratory investigations of the bending rheology of floating saline ice, and physical mechanisms of wave damping, in the HSVA ice tank","An experiment on the propagation of flexural-gravity waves was performed in
the HSVA ice tank. Physical characteristics of the water-ice system were
measured in different locations in the tank during the tests, with a number of
sensors deployed in the water, on the ice and in the air. Water velocity was
measured with an acoustic doppler velocimeter (ADV) and an acoustic doppler
current profiler (ADCP); wave amplitudes were measured with ultrasonic sensors
and the optical system Qualisys; in-plane deformations of the ice and the
temperature of the ice and water were measured by fiber optic sensors, and
acoustic emissions were recorded with compressional crystal sensors. All
together 61 tests were performed, with ice thicknesses of 3 cm and 5 cm. The
experimental setup and selected results of the tests are discussed in this
paper. We show that cyclic motion of the ice along the tank, imitating ice
drift, causes an increase in wave damping. We also show that the formation of
non-through cracks in the ice, caused by the action of waves, increases wave
damping.",1901.05333v1
2019-01-24,Generalized framework for testing gravity with gravitational-wave propagation. III. Future prospect,"The properties of gravitational-wave (GW) propagation are modified in
alternative theories of gravity and are crucial observables to test gravity at
cosmological distance. The propagation speed has already been measured from
GW170817 so precisely and pinned down to the speed of light, while other
properties of GW propagation have not constrained tightly yet. In this paper,
we investigate the measurement precisions of the amplitude damping rate
(equivalently, the time variation of the gravitational coupling for GWs) and
graviton mass in the generalized framework of GW propagation with the future
detectors such as Voyager, Cosmic Explorer, and Einstein Telescope. As a
result, we show that the future GW observation can reach 1% error for the
amplitude damping. We also study the time variation of the gravitational
couplings in Horndeski theory by performing Monte Carlo-based numerical
simulations. From the simulation results, we find that the current accelerating
Universe prefers the models with less damping of GWs and that the equivalence
principle can be tested at the level of 1% by the future GW observation.",1901.08249v2
2019-01-31,Perturbed Markov Chains and Information Networks,"The paper is devoted to studies of perturbed Markov chains commonly used for
description of information networks. In such models, the matrix of transition
probabilities for the corresponding Markov chain is usually regularised by
adding a special damping matrix multiplied by a small damping (perturbation)
parameter $\varepsilon$. We give effective upper bounds for the rate of
approximation for stationary distributions of unperturbed Markov chains by
stationary distributions of perturbed Markov chains with regularised matrices
of transition probabilities, asymptotic expansions for approximating stationary
distributions with respect to damping parameter, as well as explicit upper
bounds for the rate of convergence in ergodic theorems for $n$-step transition
probabilities in triangular array mode, where perturbation parameter
$\varepsilon \to 0$ and $n \to \infty$, simultaneously. The results of
numerical experiments are also presented",1901.11483v3
2019-02-12,Ultra-low damping in lift-off structured yttrium iron garnet thin films,"We show that using maskless photolithography and the lift-off technique,
patterned yttrium iron garnet thin films possessing ultra-low Gilbert damping
can be accomplished. The films of 70 nm thickness were grown on (001)-oriented
gadolinium gallium garnet by means of pulsed laser deposition, and they exhibit
high crystalline quality, low surface roughness, and the effective
magnetization of 127 emu/cm3. The Gilbert damping parameter is as low as
5x10-4. The obtained structures have well-defined sharp edges which along with
good structural and magnetic film properties pave a path in the fabrication of
high-quality magnonic circuits and oxide-based spintronic devices.",1902.04605v1
2019-02-14,Dynamic Interconnection and Damping Injection for Input-to-State Stable Bilateral Teleoperation,"In bilateral teleoperation, the human who operates the master and the
environment which interacts with the slave are part of the force feedback loop.
Yet, both have time-varying and unpredictable dynamics and are challenging to
model. A conventional strategy for sidestepping the demand for their models in
the stability analysis is to assume passive user and environment, and to
control the master-communications-slave system to be passive as well. This
paper circumvents the need to model the user and environment in a novel way: it
regards their forces as external excitations for a semi-autonomous force
feedback loop, which it outfits with a dynamic interconnection and damping
injection controller that renders bilateral teleoperation with time-varying
delays exponentially input-to-state stable. The controller uses the position
and velocity measurements of the local robot and the delayed position
transmitted from the other robot to robustly synchronize the master and slave
under the user and environment perturbations. Lyapunov-Krasovskii stability
analysis shows that the proposed strategy (i) can confine the position error
between the master and slave to an invariant set, and (ii) can drive it
exponentially to a globally attractive set. Thus, the dynamic interconnection
and damping injection approach has practical relevance for telemanipulation
tasks with given precision requirements.",1902.05500v1
2019-02-15,Evidence for Electron Landau Damping in Space Plasma Turbulence,"How turbulent energy is dissipated in weakly collisional space and
astrophysical plasmas is a major open question. Here, we present the
application of a field-particle correlation technique to directly measure the
transfer of energy between the turbulent electromagnetic field and electrons in
the Earth's magnetosheath, the region of solar wind downstream of the Earth's
bow shock. The measurement of the secular energy transfer from the parallel
electric field as a function of electron velocity shows a signature consistent
with Landau damping. This signature is coherent over time, close to the
predicted resonant velocity, similar to that seen in kinetic Alfv\'en
turbulence simulations, and disappears under phase randomisation. This suggests
that electron Landau damping could play a significant role in turbulent plasma
heating, and that the technique is a valuable tool for determining the particle
energisation processes operating in space and astrophysical plasmas.",1902.05785v1
2019-02-20,CoFeB/MgO/CoFeB structures with orthogonal easy axes: perpendicular anisotropy and damping,"We report on the Gilbert damping parameter $\alpha$, the effective
magnetization $4\pi M_{eff}$, and the asymmetry of the $g$-factor in
bottom-CoFeB(0.93~nm)/MgO(0.90--1.25~nm)/CoFeB(1.31~nm)-top as-deposited
systems.
  Magnetization of CoFeB layers exhibits a specific noncollinear configuration
with orthogonal easy axes and with $4\pi M_{eff}$ values of $+2.2$ kG and
$-2.3$ kG for the bottom and top layers, respectively. We show that $4\pi
M_{eff}$ depends on the asymmetry $g_\perp - g_\parallel$ of the $g$-factor
measured in the perpendicular and the in-plane directions revealing a highly
nonlinear relationship. In contrast, the Gilbert damping is practically the
same for both layers. Annealing of the films results in collinear easy axes
perpendicular to the plane for both layers. However, the linewidth is strongly
increased due to enhanced inhomogeneous broadening.",1902.07563v1
2019-02-22,Thermal induced monochromatic microwave generation in magnon-polariton,"We propose thermal induced generation of monochromatic microwave radiation in
magnon-polariton. Mechanism of thermal to microwave energy transformation is
based on intrinsic energy loss compensation of coupled magnon and microwave
cavity oscillators by thermal induced ""negative damping"". A singularity at an
exceptional point is achieved when at the critical value of ""negative damping""
the damping of the system is fully compensated. At the exceptional point, the
input energy is equally distributed between the magnon and photon subsystems of
the magnon-polariton. The efficiency of transformation of thermal energy into
useful microwave radiation is estimated to be as large as 17 percent due to
magnon-photon coupling mediated direct conversation of spin current into
microwave photons.",1902.08383v1
2019-03-04,Nonlinear inviscid damping for zero mean perturbation of the 2D Euler Couette flow,"In this note we revisit the proof of Bedrossian and Masmoudi
[arXiv:1306.5028] about the inviscid damping of planar shear flows in the 2D
Euler equations under the assumption of zero mean perturbation. We prove that a
small perturbation to the 2D Euler Couette flow in $\mathbb{T}\times
\mathbb{R}$ strongly converge to zero, under the additional assumption that the
average in $x$ is always zero. In general the mean is not a conserved quantity
for the nonlinear dynamics, for this reason this is a particular case.
Nevertheless our assumption allow the presence of echoes in the problem, which
we control by an approximation of the weight built in [arXiv:1306.5028]. The
aim of this note is to present the mathematical techniques used in
[arXiv:1306.5028] and can be useful as a first approach to the nonlinear
inviscid damping.",1903.01543v1
2019-03-10,Orbital stabilization of nonlinear systems via Mexican sombrero energy shaping and pumping-and-damping injection,"In this paper we show that a slight modification to the widely popular
interconnection and damping assignment passivity-based control
method---originally proposed for stabilization of equilibria of nonlinear
systems---allows us to provide a solution to the more challenging orbital
stabilization problem. Two different, though related, ways how this procedure
can be applied are proposed. First, the assignment of an energy function that
has a minimum in a closed curve, i.e., with the shape of a Mexican sombrero.
Second, the use of a damping matrix that changes ""sign"" according to the
position of the state trajectory relative to the desired orbit, that is,
pumping or dissipating energy. The proposed methodologies are illustrated with
the example of the induction motor and prove that it yields the industry
standard field oriented control.",1903.04070v3
2019-03-11,Impact of thermal effects on the evolution of eccentricity and inclination of low-mass planets,"Using linear perturbation theory, we evaluate the time-dependent force
exerted on an eccentric and inclined low-mass planet embedded in a gaseous
protoplanetary disc with finite thermal diffusivity $\chi$. We assume the
eccentricity and inclination to be small compared to the size of the thermal
lobes $\lambda\sim(\chi/\Omega)^{1/2}$, itself generally much smaller than the
scalelength of pressure $H$. When the planet is non-luminous, we find that its
eccentricity and inclination are vigorously damped by the disc, over a
timescale shorter by a factor $H/\lambda$ than the damping timescale in
adiabatic discs. On the contrary, when the luminosity-to-mass ratio of the
planet exceeds a threshold that depends on the disc's properties, its
eccentricity and inclination undergo an exponential growth. In the limit of a
large luminosity, the growth rate of the eccentricity is 2.5~times larger than
that of the inclination, in agreement with previous numerical work. Depending
on their luminosity, planetary embryos therefore exhibit much more diverse
behaviours than the mild damping of eccentricity and inclination considered
hitherto.",1903.04470v2
2019-03-14,The Strichartz estimates for the damped wave equation and the behavior of solutions for the energy critical nonlinear equation,"For the linear damped wave equation (DW), the $L^p$-$L^q$ type estimates have
been well studied. Recently, Watanabe showed the Strichartz estimates for DW
when $d=2,3$. In the present paper, we give Strichartz estimates for DW in
higher dimensions. Moreover, by applying the estimates, we give the local
well-posedness of the energy critical nonlinear damped wave equation (NLDW)
$\partial_t^2 u - \Delta u +\partial_t u = |u|^{\frac{4}{d-2}}u$, $(t,x) \in
[0,T) \times \mathbb{R}^d$, where $3 \leq d \leq 5$. Especially, we show the
small data global existence for NLDW. In addition, we investigate the behavior
of the solutions to NLDW. Namely, we give a decay result for solutions with
finite Strichartz norm and a blow-up result for solutions with negative Nehari
functional.",1903.05887v1
2019-04-17,Decays for Kelvin-Voigt damped wave equations I : the black box perturbative method,"We show in this article how perturbative approaches~from our work with Hitrik
(see also the work by Anantharaman-Macia) and the {\em black box} strategy
from~ our work with Zworski allow to obtain decay rates for Kelvin-Voigt damped
wave equations from quite standard resolvent estimates : Carleman estimates or
geometric control estimates for Helmoltz equationCarleman or other resolvent
estimates for the Helmoltz equation. Though in this context of Kelvin Voigt
damping, such approach is unlikely to allow for the optimal results when
additional geometric assumptions are considered (see \cite{BuCh, Bu19}), it
turns out that using this method, we can obtain the usual logarithmic decay
which is optimal in general cases. We also present some applications of this
approach giving decay rates in some particular geometries (tori).",1904.08318v2
2019-04-17,Non-Hermitian skin effect and chiral damping in open quantum systems,"One of the unique features of non-Hermitian Hamiltonians is the non-Hermitian
skin effect, namely that the eigenstates are exponentially localized at the
boundary of the system. For open quantum systems, a short-time evolution can
often be well described by the effective non-Hermitian Hamiltonians, while
long-time dynamics calls for the Lindblad master equations, in which the
Liouvillian superoperators generate time evolution. In this Letter, we find
that Liouvillian superoperators can exhibit the non-Hermitian skin effect, and
uncover its unexpected physical consequences. It is shown that the
non-Hermitian skin effect dramatically shapes the long-time dynamics, such that
the damping in a class of open quantum systems is algebraic under periodic
boundary condition but exponential under open boundary condition. Moreover, the
non-Hermitian skin effect and non-Bloch bands cause a chiral damping with a
sharp wavefront. These phenomena are beyond the effective non-Hermitian
Hamiltonians; instead, they belong to the non-Hermitian physics of full-fledged
open quantum dynamics.",1904.08432v2
2019-04-19,Plasmon-Emitter Interactions at the Nanoscale,"Plasmon-emitter interactions are of paramount importance in modern
nanoplasmonics and are generally maximal at short emitter-surface separations.
However, when the separation falls below 10-20 nm, the classical theory
progressively deteriorates due to its neglect of quantum mechanical effects
such as nonlocality, electronic spill-out, and Landau damping. Here, we show
how this neglect can be remedied by presenting a unified theoretical treatment
of mesoscopic electrodynamics grounded on the framework of Feibelman
$d$-parameters. Crucially, our technique naturally incorporates nonclassical
resonance shifts and surface-enabled Landau damping - a nonlocal damping effect
- which have a dramatic impact on the amplitude and spectral distribution of
plasmon-emitter interactions. We consider a broad array of plasmon-emitter
interactions ranging from dipolar and multipolar spontaneous emission
enhancement, to plasmon-assisted energy transfer and enhancement of two-photon
transitions. The formalism presented here gives a complete account of both
plasmons and plasmon-emitter interactions at the nanoscale, constituting a
simple yet rigorous and general platform to incorporate nonclassical effects in
plasmon-empowered nanophotonic phenomena.",1904.09279v1
2019-04-23,Ultrafast depinning of domain wall in notched antiferromagnetic nanostructures,"The pinning and depinning of antiferromagnetic (AFM) domain wall is certainly
the core issue of AFM spintronics. In this work, we study theoretically the
N\'eel-type domain wall pinning and depinning at a notch in an
antiferromagnetic (AFM) nano-ribbon. The depinning field depending on the notch
dimension and intrinsic physical parameters are deduced and also numerically
calculated. Contrary to conventional conception, it is revealed that the
depinning field is remarkably dependent of the damping constant and the
time-dependent oscillation of the domain wall position in the weakly damping
regime benefits to the wall depinning, resulting in a gradual increase of the
depinning field up to a saturation value with increasing damping constant. A
one-dimensional model accounting of the internal dynamics of domain wall is
used to explain perfectly the simulated results. It is demonstrated that the
depinning mechanism of an AFM domain wall differs from ferromagnetic domain
wall by exhibiting a depinning speed typically three orders of magnitude faster
than the latter, suggesting the ultrafast dynamics of an AFM system.",1904.10197v2
2019-08-13,"A Gevrey class semigroup, exponential decay and Lack of analyticity for a system formed by a Kirchhoff-Love plate equation and the equation of a membrane-like electric network with indirect fractional damping","The emphasis in this paper is on the Coupled System of a Kirchhoff-Love Plate
Equation with the Equation of a Membrane-like Electrical Network, where the
coupling is of higher order given by the Laplacian of the displacement velocity
$\gamma\Delta u_t$ and the Laplacian of the electric potential field
$\gamma\Delta v_t $, here only one of the equations is conservative and the
other has dissipative properties. The dissipative mechanism is given by an
intermediate damping $(-\Delta)^\theta v_t$ between the electrical damping
potential for $\theta=0$ and the Laplacian of the electric potential for
$\theta=1$. We show that $S(t)=e^{\mathbb{B}t}$ is not analytic for
$\theta\in[0, 1)$ and analytic for $\theta=1$, however $S(t)=e^{\mathbb{B}t}$
decays exponentially for $0\leq \theta\leq 1$ and $S(t)$ is of Gevrey class $s>
\frac{2+\theta}{\theta}$ when the parameter $\theta$ lies in the interval
$(0,1)$.",1908.04826v3
2019-08-20,Partial Optomechanical Refrigeration via Multimode Cold-Damping Feedback,"We provide a fully analytical treatment for the partial refrigeration of the
thermal motion of a quantum mechanical resonator under the action of feedback.
As opposed to standard cavity optomechanics where the aim is to isolate and
cool a single mechanical mode, the aim here is to extract the thermal energy
from many vibrational modes within a large frequency bandwidth. We consider a
standard cold-damping technique where homodyne read-out of the cavity output
field is fed into a feedback loop that provides a cooling action directly
applied on the mechanical resonator. Analytical and numerical results predict
that low final occupancies are achievable independently of the number of modes
addressed by the feedback as long as the cooling rate is smaller than the
intermode frequency separation. For resonators exhibiting a few nearly
degenerate pairs of modes cooling is less efficient and a weak dependence on
the number of modes is obtained. These scalings hint towards the design of
frequency resolved mechanical resonators where efficient refrigeration is
possible via simultaneous cold-damping feedback.",1908.07348v2
2019-08-19,Time Delay in the Swing Equation: A Variety of Bifurcations,"The present paper addresses the swing equation with additional delayed
damping as an example for pendulum-like systems. In this context, it is proved
that recurring sub- and supercritical Hopf bifurcations occur if time delay is
increased. To this end, a general formula for the first Lyapunov coefficient in
second order systems with additional delayed damping and delay-free
nonlinearity is given. In so far the paper extends results about stability
switching of equilibria in linear time delay systems from Cooke and Grossman.
In addition to the analytical results, periodic solutions are numerically dealt
with. The numerical results demonstrate how a variety of qualitative behaviors
is generated in the simple swing equation by only introducing time delay in a
damping term.",1908.07996v3
2019-08-26,Description and classification of 2-solitary waves for nonlinear damped Klein-Gordon equations,"We describe completely 2-solitary waves related to the ground state of the
nonlinear damped Klein-Gordon equation \begin{equation*}
\partial_{tt}u+2\alpha\partial_{t}u-\Delta u+u-|u|^{p-1}u=0 \end{equation*} on
$\bf R^N$, for $1\leq N\leq 5$ and energy subcritical exponents $p>2$. The
description is twofold.
  First, we prove that 2-solitary waves with same sign do not exist. Second, we
construct and classify the full family of 2-solitary waves in the case of
opposite signs. Close to the sum of two remote solitary waves, it turns out
that only the components of the initial data in the unstable direction of each
ground state are relevant in the large time asymptotic behavior of the
solution. In particular, we show that $2$-solitary waves have a universal
behavior: the distance between the solitary waves is asymptotic to $\log t$ as
$t\to \infty$. This behavior is due to damping of the initial data combined
with strong interactions between the solitary waves.",1908.09527v1
2019-08-30,"Magnetization reversal, damping properties and magnetic anisotropy of L10-ordered FeNi thin films","L10 ordered magnetic alloys such as FePt, FePd, CoPt and FeNi are well known
for their large magnetocrystalline anisotropy. Among these, L10-FeNi alloy is
economically viable material for magnetic recording media because it does not
contain rare earth and noble elements. In this work, L10-FeNi films with three
different strengths of anisotropy were fabricated by varying the deposition
process in molecular beam epitaxy system. We have investigated the
magnetization reversal along with domain imaging via magneto optic Kerr effect
based microscope. It is found that in all three samples, the magnetization
reversal is happening via domain wall motion. Further ferromagnetic resonance
(FMR) spectroscopy was performed to evaluate the damping constant and magnetic
anisotropy. It was observed that the FeNi sample with moderate strength of
anisotropy exhibits low value of damping constant ~ 4.9X10^-3. In addition to
this, it was found that the films possess a mixture of cubic and uniaxial
anisotropies.",1908.11761v1
2019-11-01,The spherical multipole resonance probe: kinetic damping in its spectrum,"The multipole resonance probe is one of the recently developed measurement
devices to measure plasma parameter like electron density and temperature based
on the concept of active plasma resonance spectroscopy. The dynamical
interaction between the probe and the plasma in electrostatic, kinetic
description can be modeled in an abstract notation based on functional analytic
methods. These methods provide the opportunity to derive a general solution,
which is given as the response function of the probe-plasma system. It is
defined by the matrix elements of the resolvent of an appropriate dynamical
operator. Based on the general solution a residual damping for vanishing
pressure can be predicted and can only be explained by kinetic effects. Within
this manuscript an explicit response function of the multipole resonance probe
is derived. Therefore, the resolvent is determined by its algebraic
representation based on an expansion in orthogonal basis functions. This allows
to compute an approximated response function and its corresponding spectra,
which show additional damping due to kinetic effects.",1911.00514v1
2019-11-04,Current-driven skyrmion motion in granular films,"Current-driven skyrmion motion in random granular films is investigated with
interesting findings. For a given current, there exists a critical disorder
strength below which its transverse motion could either be boosted below a
critical damping or be hindered above the critical damping, resulting in
current and disorder dependences of skyrmion Hall angle. The boosting comes
mainly from the random force that is opposite to the driving force (current).
The critical damping depends on the current density and disorder strength.
However, the longitudinal motion of a skyrmion is always hindered by the
disorder. Above the critical disorder strength, skyrmions are pinned. The
disorder-induced random force on a skyrmion can be classified as static and
kinetic ones, similar to the friction force in the Newtonian mechanics. In the
pinning phase, the static (pinning) random force is transverse to the current
density. The kinetic random force is opposite to the skyrmion velocity when
skyrmions are in motion. Furthermore, we provide strong evidences that the
Thiele equation can perfectly describe skyrmion dynamics in granular films.
These findings provide insight to skyrmion motion and should be important for
skyrmiontronics.",1911.01245v1
2019-11-05,"Reduction of damped, driven Klein-Gordon equations into a discrete nonlinear Schrödinger equation: justification and numerical comparisons","We consider a discrete nonlinear Klein-Gordon equations with damping and
external drive. Using a small amplitude ansatz, one usually approximates the
equation using a damped, driven discrete nonlinear Schr\""odinger equation.
Here, we show for the first time the justification of this approximation by
finding the error bound using energy estimate. Additionally, we prove the local
and global existence of the Schr\""odinger equation. Numerical simulations are
performed that describe the analytical results. Comparisons between discrete
breathers of the Klein-Gordon equation and discrete solitons of the discrete
nonlinear Schr\""odinger equation are presented.",1911.01631v1
2019-11-08,Giant anisotropy of Gilbert damping in a Rashba honeycomb antiferromagnet,"Giant Gilbert damping anisotropy is identified as a signature of strong
Rashba spin-orbit coupling in a two-dimensional antiferromagnet on a honeycomb
lattice. The phenomenon originates in spin-orbit induced splitting of
conduction electron subbands that strongly suppresses certain spin-flip
processes. As a result, the spin-orbit interaction is shown to support an
undamped non-equilibrium dynamical mode that corresponds to an ultrafast
in-plane N\'eel vector precession and a constant perpendicular-to-the-plane
magnetization. The phenomenon is illustrated on the basis of a two dimensional
$s$-$d$ like model. Spin-orbit torques and conductivity are also computed
microscopically for this model. Unlike Gilbert damping these quantities are
shown to reveal only a weak anisotropy that is limited to the semiconductor
regime corresponding to the Fermi energy staying in a close vicinity of
antiferromagnetic gap.",1911.03408v1
2019-11-14,Stability of coupled solitary wave in biomembranes and nerves,"In this work, we consider the electromechanical density pulse as a coupled
solitary waves represented by a longitudinal compression wave and an
out-of-plane transversal wave (i.e., perpendicular to the membrane surface). We
analyzed using, the variational approach, the characteristics of the coupled
solitary waves in the presence of damping within the framework of coupled
nonlinear Burger-Korteweg-de Vries-Benjamin-Bona-Mahony (BKdV-BBM) equation. It
is shown that, the inertia parameter increases the stability of coupled
solitary waves while the damping parameter decreases it. Moreover, the presence
of damping term induces a discontinuity of stable regions in the inertia-speed
parameter space, appearing in he form of an island of points. Bell shape and
solitary-shock like wave profiles were obtained by varying the propagation
speed and their linear stability spectrum computed. It is shown that bell shape
solitary wave exhibit bound state eigenvalue spectrum, therefore stable. On the
other hand, the solitary-shock like wave profiles exhibit unbound state
eigenvalue spectrum and are therefore generally unstable.",1911.05993v1
2019-11-19,On the theory of the nonlinear Landau damping,"An exact solution of the collisionless time-dependent Vlasov equation is
found for the first time. By means of this solution the behavior of the
Langmuir waves in the nonlinear stage is considered. The analysis is restricted
by the consideration of the first nonlinear approximation keeping the second
power of the electric strength. It is shown that in general the waves with
finite amplitudes are not subject to damping. Only in the linear approximation,
when the wave amplitude is very small, are the waves experiencing damping. It
is shown that with the definite resonance conditions imposed, the waves become
unstable.",1911.08294v2
2019-11-16,Justification of the discrete nonlinear Schrödinger equation from a parametrically driven damped nonlinear Klein-Gordon equation and numerical comparisons,"We consider a damped, parametrically driven discrete nonlinear Klein-Gordon
equation, that models coupled pendula and micromechanical arrays, among others.
To study the equation, one usually uses a small-amplitude wave ansatz, that
reduces the equation into a discrete nonlinear Schr\""odinger equation with
damping and parametric drive. Here, we justify the approximation by looking for
the error bound with the method of energy estimates. Furthermore, we prove the
local and global existence of {solutions to the discrete nonlinear}
Schr\""odinger equation. To illustrate the main results, we consider numerical
simulations showing the dynamics of errors made by the discrete nonlinear
equation. We consider two types of initial conditions, with one of them being a
discrete soliton of the nonlinear Schr\""odinger equation, that is expectedly
approximate discrete breathers of the nonlinear Klein-Gordon equation.",1911.08514v1
2019-11-26,On the Complexity of Minimum-Cost Networked Estimation of Self-Damped Dynamical Systems,"In this paper, we consider the optimal design of networked estimators to
minimize the communication/measurement cost under the networked observability
constraint. This problem is known as the minimum-cost networked estimation
problem, which is generally claimed to be NP-hard. The main contribution of
this work is to provide a polynomial-order solution for this problem under the
constraint that the underlying dynamical system is self-damped. Using
structural analysis, we subdivide the main problem into two NP-hard subproblems
known as (i) optimal sensor selection, and (ii) minimum-cost communication
network. For self-damped dynamical systems, we provide a polynomial-order
solution for subproblem (i). Further, we show that the subproblem (ii) is of
polynomial-order complexity if the links in the communication network are
bidirectional. We provide an illustrative example to explain the methodologies.",1911.11381v1
2019-12-30,A Link Between Relativistic Rest Energy and Fractionary Momentum Operators of Order 1/2,"The solution of a causal fractionary wave equation in an infinite potential
well was obtained. First, the so-called ""free particle"" case was solved, giving
as normalizable solutions a superposition of damped oscillations similar to a
wave packet. From this results, the infinite potential well case was then
solved. The damping coefficient of the equation obtained was matched with the
exponent appearing in the Yucawa potential or ""screened"" Coulomb potential.
When this matching was forced, the particle aquires an offset energy of E =
mc^2/2 which then can be increased by each energy level. The expontential
damping of the wave solutions in the box was found to be closely related with
the radius of the proton when the particle has a mass equal to the mass of the
proton. Lastly the fractionary wave equation was expressed in spherical
coordinates and remains to be solved through analytical or numerical methods.",1912.12770v4
2020-03-25,A Novel Wide-Area Control Strategy for Damping of Critical Frequency Oscillations via Modulation of Active Power Injections,"This paper proposes a novel wide-area control strategy for modulating the
active power injections to damp the critical frequency oscillations in power
systems, this includes the inter-area oscillations and the transient frequency
swing. The proposed method pursues an efficient utilization of the limited
power reserve of existing distributed energy resources (DERs) to mitigate these
oscillations. This is accomplished by decoupling the damping control actions at
different sites using the oscillation signals of the concerned mode as the
power commands. A theoretical basis for this decoupled modulating control is
provided. Technically, the desired sole modal oscillation signals are filtered
out by linearly combining the system-wide frequencies, which is determined by
the linear quadratic regulator based sparsity-promoting (LQRSP) technique. With
the proposed strategy, the modulation of each active power injection can be
effectively engineered considering the response limit and steady-state output
capability of the supporting device. The method is validated based on a
two-area test system and is further demonstrated based on the New England
39-bus test system.",2003.11397v1
2020-03-25,Sharp ultimate velocity bounds for the general solution of some linear second order evolution equation with damping and bounded forcing,"We consider a class of linear second order differential equations with
damping and external force. We investigate the link between a uniform bound on
the forcing term and the corresponding ultimate bound on the velocity of
solutions, and we study the dependence of that bound on the damping and on the
""elastic force"".
  We prove three results. First of all, in a rather general setting we show
that different notions of bound are actually equivalent. Then we compute the
optimal constants in the scalar case. Finally, we extend the results of the
scalar case to abstract dissipative wave-type equations in Hilbert spaces. In
that setting we obtain rather sharp estimates that are quite different from the
scalar case, in both finite and infinite dimensional frameworks.
  The abstract theory applies, in particular, to dissipative wave, plate and
beam equations.",2003.11579v1
2020-03-28,Energy correction based on fluorescence attenuation of DAMPE,"The major scientific goals of DArk Matter Particle Explorer (DAMPE) are to
study cosmic-ray electrons (including positrons) and gamma rays from 5 GeV to
10 TeV and nuclei from Z = 1 to 26 up to 100 TeV. The deposited energy measured
by the Bismuth Germanate Oxide (BGO) calorimeter of DAMPE is affected by
fluorescence attenuation in BGO crystals that are 600 mm long. In this work, an
in-orbit attenuation calibration method is reported, and energy correction of
the sensitive detector unit of the BGO calorimeter is also presented.",2003.12717v1
2020-05-01,Stability of Forced-Damped Response in Mechanical Systems from a Melnikov Analysis,"Frequency responses of multi-degree-of-freedom mechanical systems with weak
forcing and damping can be studied as perturbations from their conservative
limit. Specifically, recent results show how bifurcations near resonances can
be predicted analytically from conservative families of periodic orbits
(nonlinear normal modes). However, the stability of forced-damped motions is
generally determined a posteriori via numerical simulations. In this paper, we
present analytic results on the stability of periodic orbits that perturb from
conservative nonlinear normal modes. In contrast with prior approaches to the
same problem, our method can tackle strongly nonlinear oscillations, high-order
resonances and arbitrary types of non-conservative forces affecting the system,
as we show with specific examples.",2005.00444v2
2020-05-04,Remarks on asymptotic order for the linear wave equation with the scale-invariant damping and mass with $L^r$-data,"In the present paper, we consider the linear wave equation with the
scale-invariant damping and mass. It is known that the global behavior of the
solution depends on the size of the coefficients in front of the damping and
mass at initial time $t=0$. Indeed, the solution satisfies the similar decay
estimate to that of the corresponding heat equation if it is large and to that
of the modified wave equation if it is small. In our previous paper, we obtain
the scattering result and its asymptotic order for the data in the energy space
$H^1\times L^2$ when the coefficients are in the wave regime. In fact, the
threshold of the coefficients relies on the spatial decay of the initial data.
Namely, it varies depending on $r$ when the initial data is in $L^r$ ($1\leq r
< 2$). In the present paper, we will show the scattering result and the
asymptotic order in the wave regime for $L^r$-data, which is wider than the
wave regime for the data in the energy space. Moreover, we give an improvement
of the asymptotic order obtained in our previous paper for the data in the
energy space.",2005.01335v2
2020-05-13,Periodically Forced Nonlinear Oscillators With Hysteretic Damping,"We perform a detailed study of the dynamics of a nonlinear, one-dimensional
oscillator driven by a periodic force under hysteretic damping, whose linear
version was originally proposed and analyzed by Bishop in [1]. We first add a
small quadratic stiffness term in the constitutive equation and construct the
periodic solution of the problem by a systematic perturbation method,
neglecting transient terms as $t\rightarrow \infty$. We then repeat the
analysis replacing the quadratic by a cubic term, which does not allow the
solutions to escape to infinity. In both cases, we examine the dependence of
the amplitude of the periodic solution on the different parameters of the model
and discuss the differences with the linear model. We point out certain
undesirable features of the solutions, which have also been alluded to in the
literature for the linear Bishop's model, but persist in the nonlinear case as
well. Finally, we discuss an alternative hysteretic damping oscillator model
first proposed by Reid [2], which appears to be free from these difficulties
and exhibits remarkably rich dynamical properties when extended in the
nonlinear regime.",2005.06187v1
2020-05-13,Magnetic circular dichroism spectra from resonant and damped coupled cluster response theory,"A computational expression for the Faraday A term of magnetic circular
dichroism (MCD) is derived within coupled cluster response theory and
alternative computational expressions for the B term are discussed. Moreover,
an approach to compute the (temperature-independent) MCD ellipticity in the
context of coupled cluster damped response is presented, and its equivalence
with the stick-spectrum approach in the limit of infinite lifetimes is
demonstrated. The damped response approach has advantages for molecular systems
or spectral ranges with a high density of states. Illustrative results are
reported at the coupled cluster singles and doubles level and compared to
time-dependent density functional theory results.",2005.06190v1
2020-05-21,Convective Excitation and Damping of Solar-like Oscillations,"The last decade has seen a rapid development in asteroseismology thanks to
the CoRoT and Kepler missions. With more detailed asteroseismic observations
available, it is becoming possible to infer exactly how oscillations are driven
and dissipated in solar-type stars. We have carried out three-dimensional (3D)
stellar atmosphere simulations together with one-dimensional (1D) stellar
structural models of key benchmark turn-off and subgiant stars to study this
problem from a theoretical perspective. Mode excitation and damping rates are
extracted from 3D and 1D stellar models based on analytical expressions. Mode
velocity amplitudes are determined by the balance between stochastic excitation
and linear damping, which then allows the estimation of the frequency of
maximum oscillation power, $\nu_{\max}$, for the first time based on ab initio
and parameter-free modelling. We have made detailed comparisons between our
numerical results and observational data and achieved very encouraging
agreement for all of our target stars. This opens the exciting prospect of
using such realistic 3D hydrodynamical stellar models to predict solar-like
oscillations across the HR-diagram, thereby enabling accurate estimates of
stellar properties such as mass, radius and age.",2005.10519v1
2020-05-21,Non-Markovian memory in a measurement-based quantum computer,"We study the exact open system dynamics of single qubit gates during a
measurement-based quantum computation considering non-Markovian environments.
We obtain analytical solutions for the average gate fidelities and analyze it
for amplitude damping and dephasing channels. We show that the average fidelity
is identical for the X-gate and Z-gate and that neither fast application of the
projective measurements necessarily implies high gate fidelity, nor slow
application necessarily implies low gate fidelity. Indeed, for highly
non-Markovian environments, it is of utmost importance to know the best time to
perform the measurements, since a huge variation in the gate fidelity may occur
given this scenario. Furthermore, we show that while for the amplitude damping
the knowledge of the dissipative map is sufficient to determine the best
measurement times, i.e. the best times in which measures are taken, the same is
not necessarily true for the phase damping. To the later, the time of the set
of measures becomes crucial since a phase error in one qubit can fix the phase
error that takes place in another.",2005.10883v1
2020-05-22,Improving Dynamic Performance of Low-Inertia Systems through Eigensensitivity Optimization,"An increasing penetration of renewable generation has led to reduced levels
of rotational inertia and damping in the system. The consequences are higher
vulnerability to disturbances and deterioration of the dynamic response of the
system. To overcome these challenges, novel converter control schemes that
provide virtual inertia and damping have been introduced, which raises the
question of optimal distribution of such devices throughout the network. This
paper presents a framework for performance-based allocation of virtual inertia
and damping to the converter-interfaced generators in a low-inertia system.
This is achieved through an iterative, eigensensitivity-based optimization
algorithm that determines the optimal controller gains. Two conceptually
different problem formulations are presented and validated on a 3-area, 12-bus
test system.",2005.11032v1
2020-05-24,Theory of Solutions for An Inextensible Cantilever,"Recent equations of motion for the large deflections of a cantilevered
elastic beam are analyzed. In the traditional theory of beam (and plate) large
deflections, nonlinear restoring forces are due to the effect of stretching on
bending; for an inextensible cantilever, the enforcement of arc-length
preservation leads to quasilinear stiffness effects and inertial effects that
are both nonlinear and nonlocal. For this model, smooth solutions are
constructed via a spectral Galerkin approach. Additional compactness is needed
to pass to the limit, and this is obtained through a complex procession of
higher energy estimates. Uniqueness is obtained through a non-trivial
decomposition of the nonlinearity. The confounding effects of nonlinear inertia
are overcome via the addition of structural (Kelvin-Voigt) damping to the
equations of motion. Local well-posedness of smooth solutions is shown first in
the absence of nonlinear inertial effects, and then shown with these inertial
effects present, taking into account structural damping. With damping in force,
global-in-time, strong well-posedness result is obtained by achieving
exponential decay for small data.",2005.11836v2
2020-05-25,Nonlinear losses in magnon transport due to four-magnon scattering,"We report on the impact of nonlinear four-magnon scattering on magnon
transport in microstructured Co25Fe75 waveguides with low magnetic damping. We
determine the magnon propagation length with microfocused Brillouin light
scattering over a broad range of excitation powers and detect a decrease of the
attenuation length at high powers. This is consistent with the onset of
nonlinear four-magnon scattering. Hence, it is critical to stay in the linear
regime, when deriving damping parameters from the magnon propagation length.
Otherwise, the intrinsic nonlinearity of magnetization dynamics may lead to a
misinterpretation of magnon propagation lengths and, thus, to incorrect values
of the magnetic damping of the system.",2005.12113v2
2020-06-02,Rigid body dynamics of diamagnetically levitating graphite resonators,"Diamagnetic levitation is a promising technique for realizing resonant
sensors and energy harvesters, since it offers thermal and mechanical isolation
from the environment at zero power. To advance the application of
diamagnetically levitating resonators, it is important to characterize their
dynamics in the presence of both magnetic and gravitational fields. Here we
experimentally actuate and measure rigid body modes of a diamagnetically
levitating graphite plate. We numerically calculate the magnetic field and
determine the influence of magnetic force on the resonance frequencies of the
levitating plate. By analyzing damping mechanisms, we conclude that eddy
current damping dominates dissipation in mm-sized plates. We use finite element
simulations to model eddy current damping and find close agreement with
experimental results. We also study the size-dependent Q-factors (Qs) of
diamagnetically levitating plates and show that Qs above 100 million are
theoretically attainable by reducing the size of the diamagnetic resonator down
to microscale, making these systems of interest for next generation low-noise
resonant sensors and oscillators.",2006.01733v3
2020-06-11,Signatures of Spatial Curvature on Growth of Structures,"We write down Boltzmann equation for massive particles in a spatially curved
FRW universe and solve the approximate line-of-sight solution for evolution of
matter density, including the effects of spatial curvature to the first order
of approximation. It is shown that memory of early time gravitational potential
is affected by presence of spatial curvature. Then we revisit Boltzmann
equation for photons in the general FRW background. Using it, we show that how
the frequency of oscillations and damping factor (known as Silk damping)
changed in presence of spatial curvature. At last, using this modified damping
factor in hydrodynamic regime of cosmological perturbations, we find our
analytic solution which shows the effects of spatial curvature on growing mode
of matter density.",2006.06347v2
2020-06-29,"HFQPOs and discoseismic mode excitation in eccentric, relativistic discs. II. Magnetohydrodynamic simulations","Trapped inertial oscillations (r-modes) provide a promising explanation for
high-frequency quasi-periodic oscillations (HFQPOs) observed in the emission
from black hole X-ray binary systems. An eccentricity (or warp) can excite
r-modes to large amplitudes, but concurrently the oscillations are likely
damped by magnetohydrodynamic (MHD) turbulence driven by the magnetorotational
instability (MRI). We force eccentricity in global, unstratified, zero-net flux
MHD simulations of relativistic accretion discs, and find that a sufficiently
strong disc distortion generates trapped inertial waves despite this damping.
In our simulations, eccentricities above ~ 0.03 in the inner disc excite
trapped waves. In addition to the competition between r-mode damping and
driving, we observe that larger amplitude eccentric structures modify and in
some cases suppress MRI turbulence. Given the variety of distortions (warps as
well as eccentricities) capable of amplifying r-modes, the robustness of
trapped inertial wave excitation in the face of MRI turbulence in our
simulations provides support for a discoseismic explanation for HFQPOs.",2006.16266v2
2020-08-11,Ab initio results for the plasmon dispersion and damping of the warm dense electron gas,"Warm dense matter (WDM) is an exotic state on the border between condensed
matter and dense plasmas. Important occurrences of WDM include dense
astrophysical objects, matter in the core of our Earth, as well as matter
produced in strong compression experiments. As of late, x-ray Thomson
scattering has become an advanced tool to diagnose WDM. The interpretation of
the data requires model input for the dynamic structure factor $S(q,\omega)$
and the plasmon dispersion $\omega(q)$. Recently the first \textit{ab initio}
results for $S(q,\omega)$ of the homogeneous warm dense electron gas were
obtained from path integral Monte Carlo simulations, [Dornheim \textit{et al.},
Phys. Rev. Lett. \textbf{121}, 255001 (2018)]. Here, we analyse the effects of
correlations and finite temperature on the dynamic dielectric function and the
plasmon dispersion. Our results for the plasmon dispersion and damping differ
significantly from the random phase approximation and from earlier models of
the correlated electron gas. Moreover, we show when commonly used weak damping
approximations break down and how the method of complex zeros of the dielectric
function can solve this problem for WDM conditions.",2008.04605v1
2020-08-18,Singularity formation for compressible Euler equations with time-dependent damping,"In this paper, we consider the compressible Euler equations with
time-dependent damping \frac{\a}{(1+t)^\lambda}u in one space dimension. By
constructing 'decoupled' Riccati type equations for smooth solutions, we
provide some sufficient conditions under which the classical solutions must
break down in finite time. As a byproduct, we show that the derivatives blow
up, somewhat like the formation of shock wave, if the derivatives of initial
data are appropriately large at a point even when the damping coefficient goes
to infinity with a algebraic growth rate. We study the case \lambda\neq1 and
\lambda=1 respectively, moreover, our results have no restrictions on the size
of solutions and the positivity/monotonicity of the initial Riemann invariants.
In addition, for 1<\gamma<3 we provide time-dependent lower bounds on density
for arbitrary classical solutions, without any additional assumptions on the
initial data.",2008.07756v1
2020-08-18,"Survey of 360$^{\circ}$ domain walls in magnetic heterostructures: topology, chirality and current-driven dynamics","Chirality and current-driven dynamics of topologically nontrivial
360$^{\circ}$ domain walls (360DWs) in magnetic heterostructures (MHs) are
systematically investigated. For MHs with normal substrates, the static 360DWs
are N\'{e}el-type with no chirality. While for those with heavy-metal
substrates, the interfacial Dzyaloshinskii-Moriya interaction (iDMI) therein
makes 360DWs prefer specific chirality. Under in-plane driving charge currents,
as the direct result of ""full-circle"" topology a certain 360DW does not undergo
the ""Walker breakdown""-type process like a well-studied 180$^{\circ}$ domain
wall as the current density increases. Alternatively, it keeps a fixed
propagating mode (either steady-flow or precessional-flow, depending on the
effective damping constant of the MH) until it collapses or changes to other
types of solition when the current density becomes too high. Similarly, the
field-like spin-orbit torque (SOT) has no effects on the dynamics of 360DWs,
while the anti-damping SOT has. For both modes, modifications to the mobility
of 360DWs by iDMI and anti-damping SOT are provided.",2008.08196v1
2020-08-20,Combining $T_1$ and $T_2$ estimation with randomized benchmarking and bounding the diamond distance,"The characterization of errors in a quantum system is a fundamental step for
two important goals. First, learning about specific sources of error is
essential for optimizing experimental design and error correction methods.
Second, verifying that the error is below some threshold value is required to
meet the criteria of threshold theorems. We consider the case where errors are
dominated by the generalized damping channel (encompassing the common intrinsic
processes of amplitude damping and dephasing) but may also contain additional
unknown error sources. We demonstrate the robustness of standard $T_1$ and
$T_2$ estimation methods and provide expressions for the expected error in
these estimates under the additional error sources. We then derive expressions
that allow a comparison of the actual and expected results of fine-grained
randomized benchmarking experiments based on the damping parameters. Given the
results of this comparison, we provide bounds that allow robust estimation of
the thresholds for fault-tolerance.",2008.09197v1
2020-08-25,The atomic damping basis and the collective decay of interacting two-level atoms,"We find analytical solutions to the evolution of interacting two-level atoms
when the master equation is symmetric under the permutation of atomic labels.
The master equation includes atomic independent dissipation. The method to
obtain the solutions is: First, we use the system symmetries to describe the
evolution in an operator space whose dimension grows polynomially with the
number of atoms. Second, we expand the solutions in a basis composed of
eigenvectors of the dissipative part of the master equation that models the
independent dissipation of the atoms. This atomic damping basis is an atomic
analog to the damping basis used for bosonic fields. The solutions show that
the system decays as a sum of sub- and super-radiant exponential terms.",2008.11056v1
2020-09-11,Accuracy of relativistic Cowling approximation in protoneutron star asteroseismology,"The relativistic Cowling approximation, where the metric perturbations are
neglected during the fluid oscillations, is often adopted for considering the
gravitational waves from the protoneutron stars (PNSs) provided via
core-collapse supernova explosions. In this study, we evaluate how the Cowling
approximation works well by comparing the frequencies with the Cowling
approximation to those without the approximation. Then, we find that the
behavior of the frequencies with the approximation is qualitatively the same
way as that without the approximation, where the frequencies with the
approximation can totally be determined within $\sim 20\%$ accuracy. In
particular, the fundamental mode with the Cowling approximation is
overestimated. In addition, we also discuss the damping time of various
eigenmodes in gravitational waves from the PNSs, where the damping time for the
PNSs before the avoided crossing between the $f$- and $g_1$-modes, is quite
different from that for cold neutron stars, but it is more or less similar to
that for cold neutron stars in the later phase. The damping time is long enough
compared to the typical time interval of short-Fourier transformation that
often used in the analysis, and that ideally guarantees the validity of the
transformation.",2009.05206v1
2020-09-17,Resonant absorption: transformation of compressive motions into vortical motions,"This paper investigates the changes in spatial properties when
magnetohydrodynamic (MHD) waves undergo resonant damping in the Alfv\'en
continuum. The analysis is carried out for a 1D cylindrical pressure-less
plasma with a straight magnetic field. The effect of the damping on the spatial
wave variables is determined by using complex frequencies that arise as a
result of the resonant damping. Compression and vorticity are used to
characterise the spatial evolution of the MHD wave. The most striking result is
the huge spatial variation in the vorticity component parallel to the magnetic
field. Parallel vorticity vanishes in the uniform part of the equilibrium.
However, when the MHD wave moves into the non-uniform part, parallel vorticity
explodes to values that are orders of magnitude higher than those attained by
the transverse components in planes normal to the straight magnetic field. In
the non-uniform part of the equilibrium plasma, the MHD wave is controlled by
parallel vorticity and resembles an Alfv\'en wave, with the unfamiliar property
that it has pressure variations even in the linear regime.",2009.08152v1
2020-09-19,Random vibrations of stress-driven nonlocal beams with external damping,"Stochastic flexural vibrations of small-scale Bernoulli-Euler beams with
external damping are investigated by stress-driven nonlocal mechanics. Damping
effects are simulated considering viscous interactions between beam and
surrounding environment. Loadings are modeled by accounting for their random
nature. Such a dynamic problem is characterized by a stochastic partial
differential equation in space and time governing time-evolution of the
relevant displacement field. Differential eigenanalyses are performed to
evaluate modal time coordinates and mode shapes, providing a complete
stochastic description of response solutions. Closed-form expressions of power
spectral density, correlation function, stationary and non-stationary variances
of displacement fields are analytically detected. Size-dependent dynamic
behaviour is assessed in terms of stiffness, variance and power spectral
density of displacements. The outcomes can be useful for design and
optimization of structural components of modern small-scale devices, such as
Micro- and Nano-Electro-Mechanical-Systems (MEMS and NEMS).",2009.09184v1
2020-09-20,Correction Method for the Readout Saturation of the DAMPE Calorimeter,"The DArk Matter Particle Explorer (DAMPE) is a space-borne high energy
cosmic-ray and $\gamma$-ray detector which operates smoothly since the launch
on December 17, 2015. The bismuth germanium oxide (BGO) calorimeter is one of
the key sub-detectors of DAMPE used for energy measurement and electron proton
identification. For events with total energy deposit higher than decades of
TeV, the readouts of PMTs coupled on the BGO crystals would become saturated,
which results in an underestimation of the energy measurement. Based on
detailed simulations, we develop a correction method for the saturation effect
according to the shower development topologies and energies measured by
neighbouring BGO crystals. The verification with simulated and on-orbit events
shows that this method can well reconstruct the energy deposit in the saturated
BGO crystal.",2009.09438v1
2020-09-21,Complete complementarity relations in system-environment decoherent dynamics,"We investigate the system-environment information flow from the point of view
ofcomplete complementarity relations. We consider some commonly used noisy
quantum channels:Amplitude damping, phase damping, bit flip, bit-phase flip,
phase flip, depolarizing, and correlatedamplitude damping. By starting with an
entangled bipartite pure quantum state, with the linearentropy being the
quantifier of entanglement, we study how entanglement is redistributed and
turnedinto general correlations between the degrees of freedom of the whole
system. For instance, it ispossible to express the entanglement entropy in
terms of the multipartite quantum coherence or interms of the correlated
quantum coherence of the different partitions of the system. In addition,we
notice that for the depolarizing and bit-phase flip channels the wave and
particle aspects candecrease or increase together. Besides, by considering the
environment as part of a pure quantumsystem, the linear entropy is shown to be
not just a measure of mixedness of a particular subsystem,but a correlation
measure of the subsystem with rest of the world.",2009.09769v3
2020-09-15,Delay-induced resonance suppresses damping-induced unpredictability,"Combined effects of the damping and forcing in the underdamped time-delayed
Duffing oscillator are considered in this paper. We analyze the generation of a
certain damping-induced unpredictability, due to the gradual suppression of
interwell oscillations. We find the minimal amount of the forcing amplitude and
the right forcing frequency to revert the effect of the dissipation, so that
the interwell oscillations can be restored, for different time delay values.
This is achieved by using the delay-induced resonance, in which the time delay
replaces one of the two periodic forcings present in the vibrational resonance.
A discussion in terms of the time delay of the critical values of the forcing
for which the delay-induced resonance can tame the dissipation effect is
finally carried out.",2009.11760v1
2020-10-01,Modeling coupled spin and lattice dynamics,"A unified model of molecular and atomistic spin dynamics is presented
enabling simulations both in microcanonical and canonical ensembles without the
necessity of additional phenomenological spin damping. Transfer of energy and
angular momentum between the lattice and the spin systems is achieved by a
coupling term based upon the spin-orbit interaction. The characteristic spectra
of the spin and phonon systems are analyzed for different coupling strength and
temperatures. The spin spectral density shows magnon modes together with the
uncorrelated noise induced by the coupling to the lattice. The effective
damping parameter is investigated showing an increase with both coupling
strength and temperature. The model paves the way to understanding magnetic
relaxation processes beyond the phenomenological approach of the Gilbert
damping and the dynamics of the energy transfer between lattice and spins.",2010.00642v1
2020-10-06,A dissiptive logarithmic type evolution equation: asymptotic profile and optimal estimates,"We introduce a new model of the logarithmic type of wave-like equation with a
nonlocal logarithmic damping mechanism, which is rather weakly effective as
compared with frequently studied fractional damping cases. We consider the
Cauchy problem for this new model in the whole space, and study the asymptotic
profile and optimal decay and/or blowup rates of solutions as time goes to
infinity in L^{2}-sense. The operator L considered in this paper was used to
dissipate the solutions of the wave equation in the paper studied by
Charao-Ikehata in 2020, and in the low frequency parameters the principal part
of the equation and the damping term is rather weakly effective than those of
well-studied power type operators.",2010.02485v1
2020-10-12,Line-drag damping of Alfvén waves in radiatively driven winds of magnetic massive stars,"Line-driven stellar winds from massive (OB) stars are subject to a strong
line-deshadowing instability. Recently, spectropolarimetric surveys have
collected ample evidence that a subset of Galactic massive stars hosts strong
surface magnetic fields. We investigate here the propagation and stability of
magneto-radiative waves in such a magnetised, line-driven wind. Our analytic,
linear stability analysis includes line-scattering from the stellar radiation,
and accounts for both radial and non-radial perturbations. We establish a
bridging law for arbitrary perturbation wavelength after which we analyse
separately the long- and short-wavelength limits. While long-wavelength
radiative and magnetic waves are found to be completely decoupled, a key result
is that short-wavelength, radially propagating Alfv\'en waves couple to the
scattered radiation field and are strongly damped due to the line-drag effect.
This damping of magnetic waves in a scattering-line-driven flow could have
important effects on regulating the non-linear wind dynamics, and so might also
have strong influence on observational diagnostics of the wind structure and
clumping of magnetic line-driven winds.",2010.05650v1
2020-10-20,Long Time Behavior of a Quasilinear Hyperbolic System Modelling Elastic Membranes,"The paper studies the long time behavior of a system that describes the
motion of a piece of elastic membrane driven by surface tension and inner air
pressure. The system is a degenerate quasilinear hyperbolic one that involves
the mean curvature, and also includes a damping term that models the
dissipative nature of genuine physical systems. With the presence of damping, a
small perturbation of the sphere converges exponentially in time to the sphere,
and without the damping the evolution that is $\varepsilon$-close to the sphere
has life span longer than $\varepsilon^{-1/6}$. Both results are proved using a
new Nash-Moser-H\""{o}rmander type theorem proved by Baldi and Haus.",2010.10663v6
2020-10-09,Rapid parameter determination of discrete damped sinusoidal oscillations,"We present different computational approaches for the rapid extraction of the
signal parameters of discretely sampled damped sinusoidal signals. We compare
time- and frequency-domain-based computational approaches in terms of their
accuracy and precision and computational time required in estimating the
frequencies of such signals, and observe a general trade-off between precision
and speed. Our motivation is precise and rapid analysis of damped sinusoidal
signals as these become relevant in view of the recent experimental
developments in cavity-enhanced polarimetry and ellipsometry, where the
relevant time scales and frequencies are typically within the $\sim1-10\,\mu$s
and $\sim1-100$MHz ranges, respectively. In such experimental efforts,
single-shot analysis with high accuracy and precision becomes important when
developing experiments that study dynamical effects and/or when developing
portable instrumentations. Our results suggest that online, running-fashion,
microsecond-resolved analysis of polarimetric/ellipsometric measurements with
fractional uncertainties at the $10^{-6}$ levels, is possible, and using a
proof-of-principle experimental demonstration we show that using a
frequency-based analysis approach we can monitor and analyze signals at kHz
rates and accurately detect signal changes at microsecond time-scales.",2010.11690v1
2020-10-22,Effective shear and bulk viscosities for anisotropic flow,"We evaluate the viscous damping of anisotropic flow in heavy-ion collisions
for arbitrary temperature-dependent shear and bulk viscosities. We show that
the damping is solely determined by effective shear and bulk viscosities, which
are weighted averages over the temperature. We determine the relevant weights
for nucleus-nucleus collisions at $\sqrt{s_{\rm NN}}=5.02$ TeV and 200 GeV,
corresponding to the maximum LHC and RHIC energies, by running ideal and
viscous hydrodynamic simulations. The effective shear viscosity is driven by
temperatures below $210$ MeV at RHIC, and below $280$ MeV at the LHC, with the
largest contributions coming from the lowest temperatures, just above
freeze-out. The effective bulk viscosity is driven by somewhat higher
temperatures, corresponding to earlier stages of the collision. We show that at
a fixed collision energy, the effective viscosity is independent of centrality
and system size, to the same extent as the mean transverse momentum of outgoing
hadrons. The variation of viscous damping is determined by Reynolds number
scaling.",2010.11919v2
2020-10-23,Is PSR J0855$-$4644 responsible for the 1.4 TeV electron spectral bump hinted by DAMPE?,"DAMPE observation on the cosmic ray electron spectrum hints a narrow excess
at $\sim$ 1.4 TeV. Although the excess can be ascribed to dark matter
particles, pulsars and pulsar wind nebulae are believed to be a more natural
astrophysical origin: electrons injected from nearby pulsars at their early
ages can form a bump-like feature in the spectrum due to radiative energy
losses. In this paper, with a survey of nearby pulsars, we find 4 pulsars that
may have notable contributions to $\sim$ 1.4 TeV cosmic ray electrons. Among
them, PSR J0855$-$4644 has a spin down luminosity more than 50 times higher
than others and presumably dominates the electron fluxes from them. X-ray
observations on the inner compact part (which may represent a tunnel for the
transport of electrons from the pulsar) of PWN G267.0$-$01.0 are then used to
constrain the spectral index of high energy electrons injected by the pulsar.
We show that high-energy electrons released by PSR J0855$-$4644 could indeed
reproduce the 1.4 TeV spectral feature hinted by the DAMPE with reasonable
parameters.",2010.12170v1
2020-11-02,Effect of retardation on the frequency and linewidth of plasma resonances in a two-dimensional disk of electron gas,"We theoretically analyze dominant plasma modes in a two-dimensional disk of
electron gas by calculating the absorption of an incident electromagnetic wave.
The problem is solved in a self-consistent approximation, taking into account
electromagnetic retardation effects. We use the Drude model to describe the
conductivity of the system. The absorption spectrum exhibits a series of peaks
corresponding to the excitation of plasma waves. The position and linewidth of
the peaks designating, respectively, the frequency and damping rate of the
plasma modes. We estimate the influence of retardation effects on the frequency
and linewidth of the fundamental (dipole) and axisymmetric (quadrupole) plasma
modes both numerically and analytically. We find the net damping rate of the
modes to be dependent on not only the sum of the radiative and collisional
decays but also their intermixture, even for small retardation. We show that
the net damping rate can be noticeably less than that determined by collisions
alone.",2011.00877v1
2020-11-05,Low-Complexity Models for Acoustic Scene Classification Based on Receptive Field Regularization and Frequency Damping,"Deep Neural Networks are known to be very demanding in terms of computing and
memory requirements. Due to the ever increasing use of embedded systems and
mobile devices with a limited resource budget, designing low-complexity models
without sacrificing too much of their predictive performance gained great
importance. In this work, we investigate and compare several well-known methods
to reduce the number of parameters in neural networks. We further put these
into the context of a recent study on the effect of the Receptive Field (RF) on
a model's performance, and empirically show that we can achieve high-performing
low-complexity models by applying specific restrictions on the RFs, in
combination with parameter reduction methods. Additionally, we propose a
filter-damping technique for regularizing the RF of models, without altering
their architecture and changing their parameter counts. We will show that
incorporating this technique improves the performance in various low-complexity
settings such as pruning and decomposed convolution. Using our proposed filter
damping, we achieved the 1st rank at the DCASE-2020 Challenge in the task of
Low-Complexity Acoustic Scene Classification.",2011.02955v1
2020-11-14,Learning a Reduced Basis of Dynamical Systems using an Autoencoder,"Machine learning models have emerged as powerful tools in physics and
engineering. Although flexible, a fundamental challenge remains on how to
connect new machine learning models with known physics. In this work, we
present an autoencoder with latent space penalization, which discovers finite
dimensional manifolds underlying the partial differential equations of physics.
We test this method on the Kuramoto-Sivashinsky (K-S), Korteweg-de Vries (KdV),
and damped KdV equations. We show that the resulting optimal latent space of
the K-S equation is consistent with the dimension of the inertial manifold. The
results for the KdV equation imply that there is no reduced latent space, which
is consistent with the truly infinite dimensional dynamics of the KdV equation.
In the case of the damped KdV equation, we find that the number of active
dimensions decreases with increasing damping coefficient. We then uncover a
nonlinear basis representing the manifold of the latent space for the K-S
equation.",2011.07346v1
2020-11-23,Sharp lifespan estimates for the weakly coupled system of semilinear damped wave equations in the critical case,"The open question, which seems to be also the final part, in terms of
studying the Cauchy problem for the weakly coupled system of damped wave
equations or reaction-diffusion equations, is so far known as the sharp
lifespan estimates in the critical case. In this paper, we mainly investigate
lifespan estimates for solutions to the weakly coupled system of semilinear
damped wave equations in the critical case. By using a suitable test function
method associated with nonlinear differential inequalities, we catch upper
bound estimates for the lifespan. Moreover, we establish polynomial-logarithmic
type time-weighted Sobolev spaces to obtain lower bound estimates for the
lifespan in low spatial dimensions. Then, together with the derived lifespan
estimates, new and sharp results on estimates for the lifespan in the critical
case are claimed. Finally, we give an application of our results to the
semilinear reaction-diffusion system in the critical case.",2011.11366v2
2021-02-05,A simple artificial damping method for total Lagrangian smoothed particle hydrodynamics,"In this paper, we present a simple artificial damping method to enhance the
robustness of total Lagrangian smoothed particle hydrodynamics (TL-SPH).
Specifically, an artificial damping stress based on the Kelvin-Voigt type
damper with a scaling factor imitating a von Neumann-Richtmyer type artificial
viscosity is introduced in the constitutive equation to alleviate the spurious
oscillation in the vicinity of the sharp spatial gradients. After validating
the robustness and accuracy of the present method with a set of benchmark tests
with very challenging cases, we demonstrate its potentials in the field of
bio-mechanics by simulating the deformation of complex stent structures.",2102.04898v1
2021-02-18,Probing black hole microstructure with the kinetic turnover of phase transition,"By treating black hole as the macroscopic stable state on the free energy
landscape, we propose that the stochastic dynamics of the black hole phase
transition can be effectively described by the Langevin equation or
equivalently by the Fokker-Planck equation in phase space. We demonstrate the
turnover of the kinetics for the charged anti-de Sitter black hole phase
transition, which shows that the mean first passage time is linear with the
friction in the high damping regime and inversely proportional to the friction
in the low damping regime. The fluctuations in the kinetics are shown to be
large/small in the high/low damping regime and the switching behavior from the
small fluctuations to the large fluctuations takes place at the kinetic
turnover point. Because the friction is a reflection of the microscopic degrees
of freedom acting on the order parameter of the black hole, the turnover and
the corresponding fluctuations of the phase transition kinetics can be used to
probe the black hole microstructure.",2102.09439v1
2021-02-25,Energy Decay of some boundary coupled systems involving wave$\backslash$ Euler-Bernoulli beam with one locally singular fractional Kelvin-Voigt damping,"In this paper, we investigate the energy decay of hyperbolic systems of
wave-wave, wave-Euler- Bernoulli beam and beam-beam types. The two equations
are coupled through boundary connection with only one localized non-smooth
fractional Kelvin-Voigt damping. First, we reformulate each system into an
augmented model and using a general criteria of Arendt-Batty, we prove that our
models are strongly stable. Next, by using frequency domain approach, combined
with multiplier technique and some interpolation inequalities, we establish
different types of polynomial energy decay rate which depends on the order of
the fractional derivative and the type of the damped equation in the system.",2102.12732v2
2021-03-01,Fluid-plate interaction under periodic forcing,"The motion of a thin elastic plate interacting with a viscous fluid is
investigated. A periodic force acting on the plate is considered, which in a
setting without damping could lead to a resonant response. The interaction with
the viscous fluid provides a damping mechanism due to the energy dissipation in
the fluid. Moreover, an internal damping mechanism in the plate is introduced.
In this setting, we show that the periodic forcing leads to a time-periodic
(non-resonant) solution. We employ the Navier-Stokes and the Kirchhoff-Love
plate equation in a periodic cell structure to model the motion of the viscous
fluid and the elastic plate, respectively. Maximal Lp regularity for the
linearized system is established in a framework of time-periodic function
spaces. Existence of a solution to the fully nonlinear system is subsequently
shown with a fixed-point argument.",2103.00795v1
2021-03-25,Nonlinear inviscid damping and shear-buoyancy instability in the two-dimensional Boussinesq equations,"We investigate the long-time properties of the two-dimensional inviscid
Boussinesq equations near a stably stratified Couette flow, for an initial
Gevrey perturbation of size $\varepsilon$. Under the classical Miles-Howard
stability condition on the Richardson number, we prove that the system
experiences a shear-buoyancy instability: the density variation and velocity
undergo an $O(t^{-1/2})$ inviscid damping while the vorticity and density
gradient grow as $O(t^{1/2})$. The result holds at least until the natural,
nonlinear timescale $t \approx \varepsilon^{-2}$. Notice that the density
behaves very differently from a passive scalar, as can be seen from the
inviscid damping and slower gradient growth. The proof relies on several
ingredients: (A) a suitable symmetrization that makes the linear terms amenable
to energy methods and takes into account the classical Miles-Howard spectral
stability condition; (B) a variation of the Fourier time-dependent energy
method introduced for the inviscid, homogeneous Couette flow problem developed
on a toy model adapted to the Boussinesq equations, i.e. tracking the potential
nonlinear echo chains in the symmetrized variables despite the vorticity
growth.",2103.13713v1
2021-03-31,Research of Damped Newton Stochastic Gradient Descent Method for Neural Network Training,"First-order methods like stochastic gradient descent(SGD) are recently the
popular optimization method to train deep neural networks (DNNs), but
second-order methods are scarcely used because of the overpriced computing cost
in getting the high-order information. In this paper, we propose the Damped
Newton Stochastic Gradient Descent(DN-SGD) method and Stochastic Gradient
Descent Damped Newton(SGD-DN) method to train DNNs for regression problems with
Mean Square Error(MSE) and classification problems with Cross-Entropy
Loss(CEL), which is inspired by a proved fact that the hessian matrix of last
layer of DNNs is always semi-definite. Different from other second-order
methods to estimate the hessian matrix of all parameters, our methods just
accurately compute a small part of the parameters, which greatly reduces the
computational cost and makes convergence of the learning process much faster
and more accurate than SGD. Several numerical experiments on real datesets are
performed to verify the effectiveness of our methods for regression and
classification problems.",2103.16764v1
2021-04-08,Landau Damping in the Transverse Modulational Dynamics of Co-Propagating Light and Matter Beams,"The optomechanical coupling and transverse stability of a co-propagating
monochromatic electromagnetic wave and mono-energetic beam of two-level atoms
is investigated in the collisionless regime. The coupled dynamics are studied
through a Landau stability analysis of the coupled gas- kinetic and paraxial
wave equations, including the effect of the electronic nonlinearity. The
resulting dispersion relation captures the interaction of kinetic and
saturation effects and shows that for blue detuning the combined nonlinear
interaction is unstable below a critical wavenumber which reduces to the result
of Bespalov and Talanov in the limit of a negligible kinetic nonlinearity. For
red detuning we find that under a saturation parameter threshold exists whereby
the system stabilizes unconditionally. With negligible saturation, an
optomechanical form of Landau damping stabilizes all wavenumbers above a
critical wavenumber determined by the combined strength of the kinetic and
refractive optomechanical feedback. The damping is mediated primarily by atoms
traveling along the primary diagonals of the Talbot carpet.",2104.04100v1
2021-04-15,Simulating cosmological supercooling with a cold atom system II,"We perform an analysis of the supercooled state in an analogue of an early
universe phase transition based on a one dimensional, two-component Bose gas
with time-dependent interactions. We demonstrate that the system behaves in the
same way as a thermal, relativistic Bose gas undergoing a first order phase
transition. We propose a way to prepare the state of the system in the
metastable phase as an analogue to supercooling in the early universe. While we
show that parametric resonances in the system can be suppressed by thermal
damping, we find that the theoretically estimated thermal damping in our model
is too weak to suppress the resonances for realistic experimental parameters.
However, we propose that experiments to investigate the effective damping rate
in experiments would be worthwhile.",2104.07428v1
2021-04-22,Impact of Fe$_{80}$B$_{20}$ insertion on the properties of dual-MgO perpendicular magnetic tunnel junctions,"We explore the impact of Fe80B20 inserted at both
Co$_{20}$Fe$_{80}$B$_{20}$/MgO interfaces of dual-MgO free layers (FLs) in
bottom-pinned magnetic tunnel junctions (MTJs). MTJ stacks are annealed for 30
min at 350 $^\circ$C and 400 $^\circ$C in a vacuum after film deposition.
Current-in-plane tunneling measurements are carried out to characterize
magnetotransport properties of the MTJs. Conventional magnetometry measurements
and ferromagnetic resonance are conducted to estimate the saturation
magnetization, the effective perpendicular anisotropy field and the Gilbert
damping of dual-MgO FLs as a function of the Fe$_{80}$B$_{20}$ thickness and
annealing temperatures. With ultrathin Fe$_{80}$B$_{20}$ (0.2 - 0.4 nm)
inserted, perpendicular magnetic anisotropy (PMA) of FLs increases with similar
tunnel magneto-resistance (TMR) and low damping values. As Fe$_{80}$B$_{20}$
layer thickness further increases (0.6 - 1.2 nm), both TMR and PMA degrade, and
damping increases dramatically. This study demonstrates a novel approach to
tune properties of MTJ stacks with dual-MgO FLs up to 400 $^\circ$C annealing,
which enables MTJ stacks for various applications.",2104.10918v1
2021-04-29,Nano-patterning of surfaces by ion sputtering: Numerical study of the anisotropic damped Kuramoto-Sivashinsky equation,"Nonlinear models for pattern evolution by ion beam sputtering on a material
surface present an ongoing opportunity for new numerical simulations. A
numerical analysis of the evolution of preexisting patterns is proposed to
investigate surface dynamics, based on a 2D anisotropic damped
Kuramoto-Sivashinsky equation, with periodic boundary conditions. A
finite-difference semi-implicit time splitting scheme is employed on the
discretization of the governing equation. Simulations were conducted with
realistic coefficients related to physical parameters (anisotropies, beam
orientation, diffusion). The stability of the numerical scheme is analyzed with
time step and grid spacing tests for the pattern evolution, and the Method of
Manufactured Solutions has been used to verify the proposed scheme. Ripples and
hexagonal patterns were obtained from a monomodal initial condition for certain
values of the damping coefficient, while spatiotemporal chaos appeared for
lower values. The anisotropy effects on pattern formation were studied, varying
the angle of incidence of the ion beam with respect to the irradiated surface.
Analytical discussions are based on linear and weakly nonlinear analysis.",2104.14104v1
2021-05-04,Linear response theory and damped modes of stellar clusters,"Because all stars contribute to its gravitational potential, stellar clusters
amplify perturbations collectively. In the limit of small fluctuations, this is
described through linear response theory, via the so-called response matrix.
While the evaluation of this matrix is somewhat straightforward for unstable
modes (i.e. with a positive growth rate), it requires a careful analytic
continuation for damped modes (i.e. with a negative growth rate). We present a
generic method to perform such a calculation in spherically symmetric stellar
clusters. When applied to an isotropic isochrone cluster, we recover the
presence of a low-frequency weakly damped $\ell = 1$ mode. We finally use a set
of direct $N$-body simulations to test explicitly this prediction through the
statistics of the correlated random walk undergone by a cluster's density
centre.",2105.01371v1
2021-05-10,Passivity-based control of mechanical systems with linear damping identification,"We propose a control approach for a class of nonlinear mechanical systems to
stabilize the system under study while ensuring that the oscillations of the
transient response are reduced. The approach is twofold: (i) we apply our
technique for linear viscous damping identification of the system to improve
the accuracy of the selected control technique, and (ii) we implement a
passivity-based controller to stabilize and reduce the oscillations by
selecting the control parameters properly in accordance with the identified
damping. Moreover, we provide an analysis for a particular passivity-based
control approach that has been shown successfully for reducing such
oscillations. Also, we validate the methodology by implementing it
experimentally in a planar manipulator.",2105.04324v4
2021-05-26,Decay dynamics of Localised Surface Plasmons: damping of coherences and populations of the oscillatory plasmon modes,"Properties of plasmonic materials are associated with surface plasmons - the
electromagnetic excitations coupled to coherent electron charge density
oscillations on a metal/dielectric interface. Although decay of such
oscillations cannot be avoided, there are prospects for controlling plasmon
damping dynamics. In spherical metal nanoparticles (MNPs) the basic properties
of Localized Surface Plasmons (LSPs) can be controlled with their radius. The
present paper handles the link between the size-dependent description of LSP
properties derived from the dispersion relation based on Maxwell's equations
and the quantum picture in which MNPs are treated as ""quasi-particles"". Such
picture, based on the reduced density-matrix of quantum open systems ruled by
the master equation in the Lindblad form, enables to distinguish between
damping processes of populations and coherences of multipolar plasmon
oscillatory states and to establish the intrinsic relations between the rates
of these processes, independently of the size of MNP. The impact of the
radiative and the nonradiative energy dissipation channels is discussed.",2105.12463v1
2021-06-05,The electron acoustic waves in plasmas with two kappa-distributed electrons at the same temperatures and immobile ions,"The linear electron acoustic waves propagating in plasmas with two
kappa-distributed electrons and stationary ions are investigated. The
temperatures of the two electrons are assumed to be the same, but the kappa
indices are not. It shows that if one kappa index is small enough and the other
one is large enough, a weak damping regime of the electron acoustic waves
exists. The dispersions and damping rates are numerically studied. The
parameter spaces for the weakly damped electron acoustic waves are analyzed.
Moreover, the electron acoustic waves in the present model are compared with
those in other models, especially the plasmas with two-temperature electrons.
At last, we perform Vlasov-Poisson simulations to verify the theory.",2106.02910v2
2021-06-18,Global existence and asymptotic behavior for semilinear damped wave equations on measure spaces,"This paper is concerned with the semilinear damped wave equation on a measure
space with a self-adjoint operator, instead of the standard Laplace operator.
Under a certain decay estimate on the corresponding heat semigroup, we
establish the linear estimates which generalize the so-called Matsumura
estimates, and prove the small data global existence of solutions to the damped
wave equation based on the linear estimates. Our approach is based on a direct
spectral analysis analogous to the Fourier analysis. The self-adjoint operators
treated in this paper include some important examples such as the Laplace
operators on Euclidean spaces, the Dirichlet Laplacian on an arbitrary open
set, the Robin Laplacian on an exterior domain, the Schr\""odinger operator, the
elliptic operator, the Laplacian on Sierpinski gasket, and the fractional
Laplacian.",2106.10322v3
2021-06-21,On the small time asymptotics of stochastic Ladyzhenskaya-Smagorinsky equations with damping perturbed by multiplicative noise,"The Ladyzhenskaya-Smagorinsky equations model turbulence phenomena, and are
given by $$\frac{\partial \boldsymbol{u}}{\partial t}-\mu
\mathrm{div}\left(\left(1+|\nabla\boldsymbol{u}|^2\right)^{\frac{p-2}{2}}\nabla\boldsymbol{u}\right)+(\boldsymbol{u}\cdot\nabla)\boldsymbol{u}+\nabla
p=\boldsymbol{f}, \ \nabla\cdot\boldsymbol{u}=0,$$ for $p\geq 2,$ in a bounded
domain $\mathcal{O}\subset\mathbb{R}^d$ ($2\leq d\leq 4$). In this work, we
consider the stochastic Ladyzhenskaya-Smagorinsky equations with the damping
$\alpha\boldsymbol{u}+\beta|\boldsymbol{u}|^{r-2}\boldsymbol{u},$ for $r\geq 2$
($\alpha,\beta\geq 0$), subjected to multiplicative Gaussian noise. We show the
local monotoincity ($p\geq \frac{d}{2}+1,\ r\geq 2$) as well as global
monotonicity ($p\geq 2,\ r\geq 4$) properties of the linear and nonlinear
operators, which along with an application of stochastic version of
Minty-Browder technique imply the existence of a unique pathwise strong
solution. Then, we discuss the small time asymptotics by studying the effect of
small, highly nonlinear, unbounded drifts (small time large deviation
principle) for the stochastic Ladyzhenskaya-Smagorinsky equations with damping.",2106.10861v1
2021-06-23,Improved convergence rates and trajectory convergence for primal-dual dynamical systems with vanishing damping,"In this work, we approach the minimization of a continuously differentiable
convex function under linear equality constraints by a second-order dynamical
system with asymptotically vanishing damping term. The system is formulated in
terms of the augmented Lagrangian associated to the minimization problem. We
show fast convergence of the primal-dual gap, the feasibility measure, and the
objective function value along the generated trajectories. In case the
objective function has Lipschitz continuous gradient, we show that the
primal-dual trajectory asymptotically weakly converges to a primal-dual optimal
solution of the underlying minimization problem. To the best of our knowledge,
this is the first result which guarantees the convergence of the trajectory
generated by a primal-dual dynamical system with asymptotic vanishing damping.
Moreover, we will rediscover in case of the unconstrained minimization of a
convex differentiable function with Lipschitz continuous gradient all
convergence statements obtained in the literature for Nesterov's accelerated
gradient method.",2106.12294v1
2021-06-24,Landau damping of electron-acoustic waves due to multi-plasmon resonances,"The linear and nonlinear theories of electron-acoustic waves (EAWs) are
studied in a partially degenerate quantum plasma with two-temperature electrons
and stationary ions. The initial equilibrium of electrons is assumed to be
given by the Fermi-Dirac distribution at finite temperature. By employing the
multi-scale asymptotic expansion technique to the one-dimensional Wigner-Moyal
and Poisson equations, it is shown that the effects of multi-plasmon resonances
lead to a modified complex Korteweg-de Vries (KdV) equation with a new nonlocal
nonlinearity. Besides giving rise to a nonlocal nonlinear term, the
wave-particle resonance also modifies the local nonlinear coupling coefficient
of the KdV equation. The latter is shown to conserve the number of particles,
however, the wave energy decays with time. A careful analysis shows that the
two-plasmon resonance is the dominant mechanism for nonlinear Landau damping of
EAWs. An approximate soliton solution of the KdV equation is also obtained, and
it is shown that the nonlinear Landau damping causes the wave amplitude to
decay slowly with time compared to the classical theory.",2106.12754v2
2021-06-28,Stability of a Magnetically Levitated Nanomagnet in Vacuum: Effects of Gas and Magnetization Damping,"In the absence of dissipation a non-rotating magnetic nanoparticle can be
stably levitated in a static magnetic field as a consequence of the spin origin
of its magnetization. Here we study the effects of dissipation on the stability
of the system, considering the interaction with the background gas and the
intrinsic Gilbert damping of magnetization dynamics. At large applied magnetic
fields we identify magnetization switching induced by Gilbert damping as the
key limiting factor for stable levitation. At low applied magnetic fields and
for small particle dimensions magnetization switching is prevented due to the
strong coupling of rotation and magnetization dynamics, and the stability is
mainly limited by the gas-induced dissipation. In the latter case, high vacuum
should be sufficient to extend stable levitation over experimentally relevant
timescales. Our results demonstrate the possibility to experimentally observe
the phenomenon of quantum spin stabilized magnetic levitation.",2106.14858v3
2021-07-01,On behavior of solutions to a Petrovsky equation with damping and variable-exponent source,"This paper deals with the following Petrovsky equation with damping and
nonlinear source \[u_{tt}+\Delta^2 u-M(\|\nabla u\|_2^2)\Delta u-\Delta
u_t+|u_t|^{m(x)-2}u_t=|u|^{p(x)-2}u\] under initial-boundary value conditions,
where $M(s)=a+ bs^\gamma$ is a positive $C^1$ function with parameters
$a>0,~b>0,~\gamma\geq 1$, and $m(x),~p(x)$ are given measurable functions. The
upper bound of the blow-up time is derived for low initial energy using the
differential inequality technique. For $m(x)\equiv2$, in particular, the upper
bound of the blow-up time is obtained by the combination of Levine's concavity
method and some differential inequalities under high initial energy. In
addition, by making full use of the strong damping, the lower bound of the
blow-up time is discussed. Moreover, the global existence of solutions and an
energy decay estimate are presented by establishing some energy estimates and
by exploiting a key integral inequality.",2107.00273v2
2021-07-21,A combined volume penalization / selective frequency damping approach for immersed boundary methods applied to high-order schemes,"There has been an increasing interest in developing efficient immersed
boundary method (IBM) based on Cartesian grids, recently in the context of
high-order methods. IBM based on volume penalization is a robust and easy to
implement method to avoid body-fitted meshes and has been recently adapted to
high order discretisations (Kou et al., 2021). This work proposes an
improvement over the classic penalty formulation for flux reconstruction high
order solvers. We include a selective frequency damping (SFD) approach
(Aakervik et al., 2006) acting only inside solid body defined through the
immersed boundary masking, to damp spurious oscillations. An encapsulated
formulation for the SFD method is implemented, which can be used as a wrapper
around an existing time-stepping code. The numerical properties have been
studied through eigensolution analysis based on the advection equation. These
studies not only show the advantages of using the SFD method as an alternative
of the traditional volume penalization, but also show the favorable properties
of combining both approaches. This new approach is then applied to the
Navier-Stokes equation to simulate steady flow past an airfoil and unsteady
flow past a circular cylinder. The advantages of the SFD method in providing
improved accuracy are reported.",2107.10177v1
2021-07-25,Dispatch of Virtual Inertia and Damping: Numerical Method with SDP and ADMM,"Power grids are evolving toward 100% renewable energy interfaced by
inverters. Virtual inertia and damping provided by inverters are essential to
synchronism and frequency stability of future power grids. This paper
numerically addresses the problem of dispatch of virtual inertia and damping
(DID) among inverters in the transmission network. The DID problem is first
formulated as a nonlinear program (NLP) by the Radua collocation method which
is flexible to handle various types of disturbances and bounds constraints.
Since the NLP of DID is highly non-convex, semi-definite programming (SDP)
relaxation for the NLP is further derived to tackle the non-convexity, followed
by its sparsity being exploited hierarchically based on chordality of graphs to
seek enhancement of computational efficiency. Considering high dimension and
inexactness of the SDP relaxation, a feasibility-embedded distributed approach
is finally proposed under the framework of alternating direction method of
multipliers (ADMM), which achieves parallel computing and solution feasibility
regarding the original NLP. Numerical simulations carried out for five test
power systems demonstrate the proposed method and necessity of DID.",2107.11764v1
2021-07-29,Microscopic analysis of sound attenuation in low-temperature amorphous solids reveals quantitative importance of non-affine effects,"Sound attenuation in low temperature amorphous solids originates from their
disordered structure. However, its detailed mechanism is still being debated.
Here we analyze sound attenuation starting directly from the microscopic
equations of motion. We derive an exact expression for the zero-temperature
sound damping coefficient. We verify that the sound damping coefficients
calculated from our expression agree very well with results from independent
simulations of sound attenuation. The small wavevector analysis of our
expression shows that sound attenuation is primarily determined by the
non-affine displacements' contribution to the sound wave propagation
coefficient coming from the frequency shell of the sound wave. Our expression
involves only quantities that pertain to solids' static configurations. It can
be used to evaluate the low temperature sound damping coefficients without
directly simulating sound attenuation.",2107.14254v2
2021-08-09,Damping perturbation based time integration asymptotic method for structural dynamics,"The light damping hypothesis is usually assumed in structural dynamics since
dissipative forces are in general weak with respect to inertial and elastic
forces. In this paper a novel numerical method of time integration based on the
artificial perturbation of damping is proposed. The asymptotic expansion of the
transient response results in an infinite series which can be summed, leading
to a well-defined explicit iterative step-by-step scheme. Conditions for
convergence are rigorously analyzed, enabling the determination of the
methodology boundaries in form of maximum time step. The numerical properties
of the iterative scheme, i.e. stability, accuracy and computational effort are
also studied in detail. The approach is validated with two numerical examples,
showing a high accuracy and computational efficiency relative to other methods.",2108.03813v1
2021-08-12,The damping and diffusion of atoms moving in the background electromagnetic environment,"The interaction between an atom and the quantized electromagnetic field
depends on the position of the atom. Then the atom experiences a force which is
the minus gradient of this interaction. Through the Heisenberg equations of
motion and the Born-Markov approximation, the mean and correlation of the force
are obtained, showing that the center-of-mass motion of the atom is damped and
diffused. This approach can be easily generalized to multi-level atoms, where
the damping force and diffusion coefficients are just the weighted average of
the contributions from all pairs of energy levels that have nonvanishing dipole
elements. It is shown that these results are invariant under Galilean
transformation, and in principle can be used to determine the velocity of the
lab relative to the background radiation.",2108.05590v3
2021-09-22,Antibunching via cooling by heating,"We investigate statistics of the photon (phonon) field undergoing linear and
nonlinear damping processes. An effective two-photon (phonon) nonlinear
""cooling by heating"" process is realized from linear damping by spectral
filtering of the heat baths present in the system. This cooling process driven
by incoherent quantum thermal noise can create quantum states of the photon
field. In fact, for high temperatures of the spectrally filtered heat baths,
sub-Poissonian statistics with strong antibunching in the photon (phonon) field
are reported. This notion of the emergence and control of quantumness by
incoherent thermal quantum noise is applied to a quantum system comprising of a
two-level system and a harmonic oscillator or analogous optomechanical setting.
Our analysis may provide a promising direction for the preparation and
protection of quantum features via nonlinear damping that can be controlled
with incoherent thermal quantum noise.",2109.10516v2
2021-09-24,Damping in yttrium iron garnet film with an interface,"We report strong damping enhancement in a 200 nm thick yttrium iron garnet
(YIG) film due to spin inhomogeneity at the interface. The growth-induced thin
interfacial gadolinium iron garnet (GdIG) layer antiferromagnetically (AFM)
exchange couples with the rest of the YIG layer. The out-of-plane angular
variation of ferromagnetic resonance (FMR) linewidth $\Delta H$ reflects a
large inhomogeneous distribution of effective magnetization $\Delta 4 \pi
M_{eff}$ due to the presence of an exchange springlike moments arrangement in
YIG. We probe the spin inhomogeneity at the YIG-GdIG interface by performing an
in-plane angular variation of resonance field $H_{r}$, leading to a
unidirectional feature. The large extrinsic $\Delta 4\pi M_{eff}$ contribution,
apart from the inherent intrinsic Gilbert contribution, manifests enhanced
precessional damping in YIG film.",2109.12071v1
2021-10-13,Tutorial on stochastic systems,"In this tutorial, three examples of stochastic systems are considered: A
strongly-damped oscillator, a weakly-damped oscillator and an undamped
oscillator (integrator) driven by noise. The evolution of these systems is
characterized by the temporal correlation functions and spectral densities of
their displacements, which are determined and discussed. Damped oscillators
reach steady stochastic states. Their correlations are decreasing functions of
the difference between the sample times and their spectra have peaks near their
resonance frequencies. An undamped oscillator never reaches a steady state. Its
energy increases with time and its spectrum is sharply peaked at low
frequencies. The required mathematical methods and physical concepts are
explained on a just-in-time basis, and some theoretical pitfalls are mentioned.
The insights one gains from studies of oscillators can be applied to a wide
variety of physical systems, such as atom and semiconductor lasers, which will
be discussed in a subsequent tutorial.",2110.06966v1
2021-10-18,Structured vector fitting framework for mechanical systems,"In this paper, we develop a structure-preserving formulation of the
data-driven vector fitting algorithm for the case of modally damped mechanical
systems. Using the structured pole-residue form of the transfer function of
modally damped second-order systems, we propose two possible structured
extensions of the barycentric formula of system transfer functions. Integrating
these new forms within the classical vector fitting algorithm leads to the
formulation of two new algorithms that allow the computation of modally damped
mechanical systems from data in a least squares fashion. Thus, the learned
model is guaranteed to have the desired structure. We test the proposed
algorithms on two benchmark models.",2110.09220v1
2021-10-27,Integrability and solvability of polynomial Liénard differential systems,"We provide the necessary and sufficient conditions of Liouvillian
integrability for Li\'{e}nard differential systems describing nonlinear
oscillators with a polynomial damping and a polynomial restoring force. We
prove that Li\'{e}nard differential systems are not Darboux integrable
excluding subfamilies with certain restrictions on the degrees of the
polynomials arising in the systems. We demonstrate that if the degree of a
polynomial responsible for the restoring force is greater than the degree of a
polynomial producing the damping, then a generic Li\'{e}nard differential
system is not Liouvillian integrable with the exception of linear Li\'{e}nard
systems. However, for any fixed degrees of the polynomials describing the
damping and the restoring force we present subfamilies possessing Liouvillian
first integrals. As a by-product of our results, we find a number of novel
Liouvillian integrable subfamilies. In addition, we study the existence of
non-autonomous Darboux first integrals and non-autonomous Jacobi last
multipliers with a time-dependent exponential factor.",2110.14306v2
2021-10-28,Global Solution to the Vacuum Free Boundary Problem with Physical Singularity of Compressible Euler Equations with Damping and Gravity,"The global existence of smooth solutions to the vacuum free boundary problem
with physical singularity of compressible Euler equations with damping and
gravity is proved in space dimensions $n=1, 2, 3$, for the initial data being
small perturbations of the stationary solution. Moreover, the exponential decay
of the velocity is obtained for $n=1, 2, 3$. The exponentially fast convergence
of the density and vacuum boundary to those of the stationary solution is shown
for $n=1$, and it is proved for $n=2, 3$ that they stay close to those of the
stationary solution if they do so initially. The proof is based on the weighted
estimates of both hyperbolic and parabolic types with weights capturing the
singular behavior of higher-order normal derivatives near vacuum states,
exploring the balance between the physical singularity which pushes the vacuum
boundary outwards and the effect of gravity which pulls it inwards, and the
dissipation of the frictional damping. The results obtained in this paper are
the first ones on the global existence of solutions to the vacuum free boundary
problems of inviscid compressible fluids with the non-expanding background
solutions. Exponentially fast convergence when the vacuum state is involved
discovered in this paper is a new feature of the problem studied.",2110.14909v1
2021-10-29,Spinons and damped phonons in spin-1/2 quantum-liquid Ba$_{4}$Ir${}_3$O${}_{10}$ observed by Raman scattering,"In spin-1/2 Mott insulators, non-magnetic quantum liquid phases are often
argued to arise when the system shows no magnetic ordering, but identifying
positive signatures of these phases or related spinon quasiparticles can be
elusive. Here we use Raman scattering to provide three signatures for spinons
in a possible spin-orbit quantum liquid material Ba${}_4$Ir${}_3$O${}_{10}$:
(1) A broad hump, which we show can arise from Luttinger Liquid spinons in
Raman with parallel photon polarizations normal to 1D chains; (2) Strong phonon
damping from phonon-spin coupling via the spin-orbit interaction; and (3) the
absence of (1) and (2) in the magnetically ordered phase that is produced when
2% of Ba is substituted by Sr
((Ba${}_{0.98}$Sr${}_{0.02}$)${}_4$Ir${}_3$O${}_{10}$). The phonon damping via
itinerant spinons seen in this quantum-liquid insulator suggests a new
mechanism for enhancing thermoelectricity in strongly correlated conductors,
through a neutral quantum liquid that need not affect electronic transport.",2110.15916v1
2021-10-31,Thermally induced all-optical ferromagnetic resonance in thin YIG films,"All-optical ferromagnetic resonance (AO-FMR) is a powerful tool for local
detection of micromagnetic parameters, such as magnetic anisotropy, Gilbert
damping or spin stiffness. In this work we demonstrate that the AO-FMR method
can be used in thin films of Yttrium Iron Garnet (YIG) if a metallic capping
layer (Au, Pt) is deposited on top of the film. Magnetization precession is
triggered by heating of the metallic layer with femtosecond laser pulses. The
heating modifies the magneto-crystalline anisotropy of the YIG film and shifts
the quasi-equilibrium orientation of magnetization, which results in
precessional magnetization dynamics. The laser-induced magnetization precession
corresponds to a uniform (Kittel) magnon mode, with the precession frequency
determined by the magnetic anisotropy of the material as well as the external
magnetic field, and the damping time set by a Gilbert damping parameter. The
AO-FMR method thus enables measuring local magnetic properties, with spatial
resolution given only by the laser spot size.",2111.00586v1
2021-11-03,Pointwise space-time estimates of two-phase fluid model in dimension three,"In this paper, we investigate the pointwise space-time behavior of two-phase
fluid model derived by Choi \cite{Choi} [SIAM J. Math. Anal., 48(2016), pp.
3090-3122], which is the compressible damped Euler equations coupled with
compressible Naiver-Stokes equations. Based on Green's function method together
with frequency analysis and nonlinear coupling of different wave patterns, it
shows that both of two densities and momentums obey the generalized Huygens'
principle as the compressible Navier-Stokes equations \cite{LW}, however, it is
different from the compressible damped Euler equations \cite{Wang2}. The main
contributions include seeking suitable combinations to avoid the singularity
from the Hodge decomposition in the low frequency part of the Green's function,
overcoming the difficulty of the non-conservation arising from the damped
mechanism of the system, and developing the detailed description of the
singularities in the high frequency part of the Green's function. Finally, as a
byproduct, we extend $L^2$-estimate in \cite{Wugc} [SIAM J. Math. Anal.,
52(2020), pp. 5748-5774] to $L^p$-estimate with $p>1$.",2111.01987v1
2021-11-09,Turbulent cascades for a family of damped Szegö equations,"In this paper, we study the transfer of energy from low to high frequencies
for a family of damped Szeg\""o equations. The cubic Szeg\""o equation has been
introduced as a toy model for a totally non-dispersive degenerate Hamiltonian
equation. It is a completely integrable system which develops growth of high
Sobolev norms, detecting transfer of energy and hence cascades phenomena.
  Here, we consider a two-parameter family of variants of the cubic Szeg\""o
equation and prove that adding a damping term unexpectedly promotes the
existence of turbulent cascades. Furthermore, we give a panorama of the
dynamics for such equations on a six-dimensional submanifold.",2111.05247v1
2021-11-18,Sharp Stability of a String with Local Degenerate Kelvin-Voigt Damping,"This paper is on the asymptotic behavior of the elastic string equation with
localized degenerate Kelvin--Voigt damping $$
u_{tt}(x,t)-[u_{x}(x,t)+b(x)u_{x,t}(x,t)]_{x}=0,\; x\in(-1,1),\; t>0,$$ where
$b(x)=0$ on $x\in (-1,0]$, and $b(x)=x^\alpha>0$ on $x\in (0,1)$ for
$\alpha\in(0,1)$. It is known that the optimal decay rate of solution is
$t^{-2}$ in the limit case $\alpha=0$, and exponential decay rate for
$\alpha\ge 1$. When $\alpha\in (0,1)$, the damping coefficient $b(x)$ is
continuous, but its derivative has a singularity at the interface $x=0$. In
this case, the best known decay rate is $t^{-\frac{3-\alpha}{2(1-\alpha)}}$.
Although this rate is consistent with the exponential one at $\alpha=1$, it
failed to match the optimal one at $\alpha=0$.
  In this paper, we obtain a sharper polynomial decay rate
$t^{-\frac{2-\alpha}{1-\alpha}}$. More significantly, it is consistent with the
optimal polynomial decay rate at $\alpha=0$ and the exponential decay rate at
$\alpha = 1$.This is a big step toward the goal of obtaining eventually the
optimal decay rate.",2111.09500v1
2021-11-22,Global well-posedness for a generalized Keller-Segel system with degenerate dissipation and mixing,"We study the mixing effect for a generalized Keller-Segel system with
degenerate dissipation and advection by a weakly mixing. Here the attractive
operator has weak singularity, namely, the negative derivative appears in the
nonlinear term by singular integral. Without advection, the solution of
equation blows up in finite time. We show that the global well-posedness of
solution with large advection. Since dissipation term degenerate into the
damping, the enhanced dissipation effect of mixing no longer occurs, we prove
that the mixing effect can weak the influence of nonlinear term. In this case,
the mixing effect is similar with inviscid damping of shear flow. Combining to
the mixing effect and damping effect of degenerate dissipation, the global
$L^\infty$ estimate of solution is established.",2111.11083v1
2021-11-26,Damping of Pseudo-Goldstone Fields,"Approximate symmetries abound in Nature. If these symmetries are also
spontaneously broken, the would-be Goldstone modes acquire a small mass, or
inverse correlation length, and are referred to as pseudo-Goldstones. At
nonzero temperature, the effects of dissipation can be captured by
hydrodynamics at sufficiently long scales compared to the local equilibrium.
Here we show that in the limit of weak explicit breaking, locality of
hydrodynamics implies that the damping of pseudo-Goldstones is completely
determined by their mass and diffusive transport coefficients. We present many
applications: superfluids, QCD in the chiral limit, Wigner crystal and density
wave phases in the presence of an external magnetic field or not, nematic
phases and (anti-)ferromagnets. For electronic density wave phases,
pseudo-Goldstone damping generates a contribution to the resistivity
independent of the strength of disorder, which can have a linear temperature
dependence provided the associated diffusivity saturates a bound. This is
reminiscent of the phenomenology of strange metal high $T_c$ superconductors,
where charge density waves are observed across the phase diagram.",2111.13459v2
2021-11-26,Transition from order to chaos in reduced quantum dynamics,"We study a damped kicked top dynamics of a large number of qubits ($N
\rightarrow \infty$) and focus on an evolution of a reduced single-qubit
subsystem. Each subsystem is subjected to the amplitude damping channel
controlled by the damping constant $r\in [0,1]$, which plays the role of the
single control parameter. In the parameter range for which the classical
dynamics is chaotic, while varying $r$ we find the universal period-doubling
behavior characteristic to one-dimensional maps: period-two dynamics starts at
$r_1 \approx 0.3181$, while the next bifurcation occurs at $ r_2 \approx
0.5387$. In parallel with period-four oscillations observed for $r \leq r_3
\approx 0.5672$, we identify a secondary bifurcation diagram around $r\approx
0.544$, responsible for a small-scale chaotic dynamics inside the attractor.
The doubling of the principal bifurcation tree continues until $r \leq
r_{\infty} \sim 0.578$, which marks the onset of the full scale chaos
interrupted by the windows of the oscillatory dynamics corresponding to the
Sharkovsky order.",2111.13477v1
2021-12-06,"Damped physical oscillators, temperature and chemical clocks","The metaphor of a clock in physics describes near-equilibrium reversible
phenomena such as an oscillating spring. It is surprising that for chemical and
biological clocks the focus has been exclusively on the far-from-equilibrium
dissipative processes. We show here that one can represent chemical
oscillations (the Lotka-Volterra system and the Brusselator) by equations
analogous to Onsager's phenomenological equations when the condition of the
reciprocal relations, i.e. the symmetry in the coupling of thermodynamic forces
to fluxes is relaxed and antisymmetric contributions are permitted. We compare
these oscillations to damped oscillators in physics (e.g., springs, coupled
springs and electrical circuits) which are represented by similar equations.
Onsager's equations and harmonic Hamiltonian systems are shown to be limiting
cases of a more general formalism.
  The central element of un-damped physical oscillations is the conservation of
entropy which unavoidably results in reversible temperature oscillations. Such
temperature oscillations exist in springs and electrical LC-circuits, but have
among others also been found in the oscillating Belousov-Zhabotinsky reaction,
in oscillations of yeast cells, and during the nervous impulse. This suggests
that such oscillations contain reversible entropy-conserving elements, and that
physical and chemical clocks may be more similar than expected.",2112.03083v1
2021-12-10,Existence of Zero-damped Quasinormal Frequencies for Nearly Extremal Black Holes,"It has been observed that many spacetimes which feature a near-extremal
horizon exhibit the phenomenon of zero-damped modes. This is characterised by
the existence of a sequence of quasinormal frequencies which all converge to
some purely imaginary number $i\alpha$ in the extremal limit and cluster in a
neighbourhood of the line $\Im s=\alpha$. In this paper, we establish that this
property is present for the conformal Klein-Gordon equation on a
Reissner-Nordstr\""om-de Sitter background. This follows from a similar result
that we prove for a class of spherically symmetric black hole spacetimes with a
cosmological horizon. We also show that the phenomenon of zero-damped modes is
stable to perturbations that arise through adding a potential.",2112.05669v3
2021-12-22,Quantifying Spin-Orbit Torques in Antiferromagnet/Heavy Metal Heterostructures,"The effect of spin currents on the magnetic order of insulating
antiferromagnets (AFMs) is of fundamental interest and can enable new
applications. Toward this goal, characterizing the spin-orbit torques (SOT)
associated with AFM/heavy metal (HM) interfaces is important. Here we report
the full angular dependence of the harmonic Hall voltages in a predominantly
easy-plane AFM, epitaxial c-axis oriented $\alpha$-Fe$_2$O$_3$ films, with an
interface to Pt. By modeling the harmonic Hall signals together with the
$\alpha$-Fe$_2$O$_3$ magnetic parameters, we determine the amplitudes of
field-like and damping-like SOT. Out-of-plane field scans are shown to be
essential to determining the damping-like component of the torques. In contrast
to ferromagnetic/heavy metal heterostructures, our results demonstrate that the
field-like torques are significantly larger than the damping-like torques,
which we correlate with the presence of a large imaginary component of the
interface spin-mixing conductance. Our work demonstrates a direct way of
characterizing SOT in AFM/HM heterostructures.",2112.12238v1
2022-01-04,Focusing of nonlinear eccentric waves in astrophysical discs. II. Excitation and damping of tightly-wound waves,"In this paper I develop a nonlinear theory of tightly-wound (highly twisted)
eccentric waves in astrophysical discs, based on the averaged Lagrangian method
of Whitham. Viscous dissipation is included in the theory by use of a
pseudo-Lagrangian. This work is an extension of the theory developed by Lee \&
Goodman to 3D discs, with the addition of viscosity. I confirm that linear
tightly-wound eccentric waves are overstable and are excited by the presence of
a shear viscosity and show this persists for weakly nonlinear waves. I find the
waves are damped by shear viscosity when the wave become sufficiently
nonlinear, a result previously found in particulate discs. Additionally I
compare the results of this model to recent simulations of eccentric waves
propagating in the inner regions of black hole discs and show that an ingoing
eccentric wave can be strongly damped near the marginally stable orbit,
resulting in a nearly circular disc with a strong azimuthal variation in the
disc density.",2201.01156v1
2022-01-12,Local Well-Posedness of the Gravity-Capillary Water Waves System in the Presence of Geometry and Damping,"We consider the gravity-capillary water waves problem in a domain $\Omega_t
\subset \mathbb{T} \times \mathbb{R}$ with substantial geometric features.
Namely, we consider a variable bottom, smooth obstacles in the flow and a
constant background current. We utilize a vortex sheet model introduced by
Ambrose, et. al. in arXiv:2108.01786. We show that the water waves problem is
locally-in-time well-posed in this geometric setting and study the lifespan of
solutions. We then add a damping term and derive evolution equations that
account for the damper. Ultimately, we show that the same well-posedness and
lifespan results apply to the damped system. We primarily utilize energy
methods.",2201.04713v2
2022-02-04,"Finite-temperature plasmons, damping and collective behavior for $α-\mathcal{T}_3$ model","We have conducted a thorough theoretical and numerical investigation of the
electronic susceptibility, polarizability, plasmons, their damping rates, as
well as the static screening in pseudospin-1 Dirac cone materials with a flat
band, or for a general $\alpha - \mathcal{T}_3$ model, at finite temperatures.
This includes calculating the polarization function, plasmon dispersions and
their damping rates at arbitrary temperatures and obtaining analytical
approximations the long wavelength limit, low and high temperatures. We
demonstrate that the integral transformation of the polarization function
cannot be used directly for a dice lattice revealing some fundamental
properties and important applicability limits of the flat band dispersions
model. At $k_B T \ll E_F$, the largest temperature-induced change of the
polarization function and plasmons comes from the mismatch between the chemical
potential and the Fermi energy. We have also obtained a series of closed-form
semi-analytical expressions for the static limit of the polarization function
of an arbitrary $\alpha - \mathcal{T}_3$ material at any temperature with exact
analytical formulas for the high, low and zero temperature limits which is of
tremendous importance for all types of transport and screening calculations for
the flat band Dirac materials.",2202.01945v1
2022-02-04,Enhancing the Formation of Wigner Negativity in a Kerr Oscillator via Quadrature Squeezing,"Motivated by quantum experiments with nanomechanical systems, the evolution
of a Kerr oscillator with focus on creation of states with a negative Wigner
function is investigated. Using the phase space formalism, results are
presented that demonstrate an asymptotic behavior in the large squeezing regime
for the negativity of a squeezed vacuum state under unitary evolution. The
analysis and model are extended to squeezed vacuum states of open systems,
adding the decoherence effects of damping and dephasing. To increase
experimental relevance, the regime of strong damping is considered. These
effects are investigated, yielding similar asymptotic results for the behavior
of these effects in the large squeezing regime. Combining these results, it is
shown that a weak nonlinearity as compared to damping may be improved by
increasing the squeezing of the initial state. It is also shown that this may
be done without exacerbating the effects of dephasing.",2202.02285v1
2022-02-11,"Spin stiffness, spectral weight, and Landau damping of magnons in metallic spiral magnets","We analyze the properties of magnons in metallic electron systems with spiral
magnetic order. Our analysis is based on the random phase approximation for the
susceptibilities of tight binding electrons with a local Hubbard interaction in
two or three dimensions. We identify three magnon branches from poles in the
susceptibilities, one associated with in-plane, the other two associated with
out-of-plane fluctuations of the spiral order parameter. We derive general
expressions for the spin stiffnesses and the spectral weights of the magnon
modes, from which also the magnon velocities can be obtained. Moreover, we
determine the size of the decay rates of the magnons due to Landau damping.
While the decay rate of the in-plane mode is of the order of its excitation
energy, the decay rate of the out-of-plane mode is smaller so that these modes
are asymptotically stable excitations even in the presence of Landau damping.",2202.05660v1
2022-02-12,Generalization of the Landau-Lifshitz-Gilbert equation by multi-body contributions to Gilbert damping for non-collinear magnets,"We propose a systematic and sequential expansion of the
Landau-Lifshitz-Gilbert equation utilizing the dependence of the Gilbert
damping tensor on the angle between magnetic moments, which arises from
multi-body scattering processes. The tensor consists of a damping-like term and
a correction to the gyromagnetic ratio. Based on electronic structure theory,
both terms are shown to depend on e.g. the scalar, anisotropic, vector-chiral
and scalar-chiral products of magnetic moments: $\vec{e}_i\cdot\vec{e}_j$,
$(\vec{n}_{ij}\cdot\vec{e}_i)(\vec{n}_{ij}\cdot\vec{e}_j)$,
$\vec{n}_{ij}\cdot(\vec{e}_i\times\vec{e}_j)$, $(\vec{e}_i\cdot\vec{e}_j)^2$,
$\vec{e}_i\cdot(\vec{e}_j\times\vec{e}_k)$..., where some terms are subjected
to the spin-orbit field $\vec{n}_{ij}$ in first and second order. We explore
the magnitude of the different contributions using both the Alexander-Anderson
model and time-dependent density functional theory in magnetic adatoms and
dimers deposited on Au(111) surface.",2202.06154v1
2022-02-16,On the strong convergence of the trajectories of a Tikhonov regularized second order dynamical system with asymptotically vanishing damping,"This paper deals with a second order dynamical system with vanishing damping
that contains a Tikhonov regularization term, in connection to the minimization
problem of a convex Fr\'echet differentiable function $g$.
  We show that for appropriate Tikhonov regularization parameters the value of
the objective function in a generated trajectory converges fast to the global
minimum of the objective function and a trajectory generated by the dynamical
system converges weakly to a minimizer of the objective function. We also
obtain the fast convergence of the velocities towards zero and some integral
estimates. Nevertheless, our main goal is to extend and improve some recent
results obtained in \cite{ABCR} and \cite{AL-nemkoz} concerning the strong
convergence of the generated trajectories to an element of minimal norm from
the $\argmin$ set of the objective function $g$. Our analysis also reveals that
the damping coefficient and the Tikhonov regularization coefficient are
strongly correlated.",2202.08980v1
2022-04-01,Effect of interfacial spin mixing conductance on gyromagnetic ratio of Gd substituted Y$_{3}$Fe$_{5}$O$_{12}$,"Due to its low intrinsic damping, Y$_3$Fe$_5$O$_{12}$ and its substituted
variations are often used for ferromagnetic layer at spin pumping experiment.
Spin pumping is an interfacial spin current generation in the interface of
ferromagnet and non-magnetic metal, governed by spin mixing conductance
parameter $G^{\uparrow\downarrow}$. $G^{\uparrow\downarrow}$ has been shown to
enhance the damping of the ferromagnetic layer. The theory suggested that the
effect of $G^{\uparrow\downarrow}$ on gyromagnetic ratio only come from its
negligible imaginary part. In this article, we show that the different damping
of ferrimagnetic lattices induced by $G^{\uparrow\downarrow}$ can affect the
gyromagnetic ratio of Gd-substituted Y$_3$Fe$_5$O$_{12}$.",2204.00310v1
2022-04-04,A Vanka-based parameter-robust multigrid relaxation for the Stokes-Darcy Brinkman problems,"We propose a block-structured multigrid relaxation scheme for solving the
Stokes-Darcy Brinkman equations discretized by the marker and cell scheme. An
element-based additive Vanka smoother is used to solve the corresponding
shifted Laplacian operator. Using local Fourier analysis, we present the
stencil for the additive Vanka smoother and derive an optimal smoothing factor
for Vanka-based Braess-Sarazin relaxation for the Stokes-Darcy Brinkman
equations. Although the optimal damping parameter is dependent on meshsize and
physical parameter, it is very close to one. Numerical results of two-grid and
V(1,1)-cycle are presented, which show high efficiency of the proposed
relaxation scheme and its robustness to physical parameters and the meshsize.
Using a damping parameter equal to one gives almost the same results as these
for the optimal damping parameter at a lower computational overhead.",2204.01237v1
2022-04-19,Blow-up and lifespan estimate for wave equations with critical damping term of space-dependent type related to Glassey conjecture,"The main purpose of the present paper is to study the blow-up problem of the
wave equation with space-dependent damping in the \textit{scale-invariant case}
and time derivative nonlinearity with small initial data. Under appropriate
initial data which are compactly supported, by using a test function method and
taking into account the effect of the damping term
($\frac{\mu}{\sqrt{1+|x|^2}}u_t$), we provide that in higher dimensions the
blow-up region is given by $p \in (1, p_G(N+\mu)]$ where $p_G(N)$ is the
Glassey exponent. Furthermore, we shall establish a blow-up region, independent
of $\mu$ given by $p\in (1, 1+\frac{2}{N}),$ for appropriate initial data in
the energy space with noncompact support.",2204.09156v1
2022-04-28,Strong coupling of quantum emitters and the exciton polariton in MoS$_2$ nanodisks,"As a quasiparticle formed by light and excitons in semiconductors, the
exciton-polariton (EP) as a quantum bus is promising for the development of
quantum interconnect devices at room temperature. However, the significant
damping of EPs in the material generally causes a loss of quantum information.
We propose a mechanism to overcome the destructive effect of a damping EP on
its mediated correlation dynamics of quantum emitters (QEs). Via an
investigation of the near-field coupling between two QEs and the EP in a
monolayer MoS$_{2}$ nanodisk, we find that, with the complete dissipation of
the QEs efficiently avoided, a persistent quantum correlation between the QEs
can be generated and stabilized even to their steady state. This is due to the
fact that, with upon decreasing the QE-MoS$_2$ distance, the QEs become so
hybridized with the EP that one or two bound states are formed between them.
Our result supplies a useful way to avoid the destructive impact of EP damping,
and it refreshes our understanding of the light-matter interaction in absorbing
medium.",2204.13383v2
2022-05-09,Scalable all-optical cold damping of levitated nanoparticles,"The field of levitodynamics has made significant progress towards controlling
and studying the motion of a levitated nanoparticle. Motional control relies on
either autonomous feedback via a cavity or measurement-based feedback via
external forces. Recent demonstrations of measurement-based ground-state
cooling of a single nanoparticle employ linear velocity feedback, also called
cold damping, and require the use of electrostatic forces on charged particles
via external electrodes. Here we introduce a novel all-optical cold damping
scheme based on spatial modulation of the trap position that is scalable to
multiple particles. The scheme relies on using programmable optical tweezers to
provide full independent control over trap frequency and position of each
tweezer. We show that the technique cools the center-of-mass motion of
particles down to $17\,$mK at a pressure of $2 \times 10^{-6}\,$mbar and
demonstrate its scalability by simultaneously cooling the motion of two
particles. Our work paves the way towards studying quantum interactions between
particles, achieving 3D quantum control of particle motion without cavity-based
cooling, electrodes or charged particles, and probing multipartite entanglement
in levitated optomechanical systems.",2205.04455v1
2022-06-08,Thermal ion kinetic effects and Landau damping in fishbone modes,"The kinetic-MHD hybrid simulation approach for macroscopic instabilities in
plasmas can be extended to include the kinetic effects of both thermal ions and
energetic ions. The new coupling scheme includes synchronization of density and
parallel velocity between thermal ions and MHD, in addition to pressure
coupling, to ensure the quasineutrality condition and avoid numerical errors.
The new approach has been implemented in the kinetic-MHD code M3D-C1-K, and was
used to study the thermal ion kinetic effects and Landau damping in fishbone
modes in both DIII-D and NSTX. It is found that the thermal ion kinetic effects
can cause an increase of the frequencies of the non-resonant $n=1$ fishbone
modes driven by energetic particles for $q_\mathrm{min}>1$, and Landau damping
can provide additional stabilization effects. A nonlinear simulation for $n=1$
fishbone mode in NSTX is also performed, and the perturbation on magnetic flux
surfaces and the transport of energetic particles are calculated.",2206.03648v1
2022-07-12,Resonant Multilevel Amplitude Damping Channels,"We introduce a new set of quantum channels: resonant multilevel amplitude
damping (ReMAD) channels. Among other instances, they can describe energy
dissipation effects in multilevel atomic systems induced by the interaction
with a zero-temperature bosonic environment. At variance with the already known
class of multilevel amplitude damping (MAD) channels, this new class of maps
allows the presence of an environment unable to discriminate transitions with
identical energy gaps. After characterizing the algebra of their composition
rules, by analyzing the qutrit case, we show that this new set of channels can
exhibit degradability and antidegradability in vast regions of the allowed
parameter space. There we compute their quantum capacity and private classical
capacity. We show that these capacities can be computed exactly also in regions
of the parameter space where the channels aren't degradable nor antidegradable.",2207.05646v2
2022-07-14,Estimates for the nonlinear viscoelastic damped wave equation on compact Lie groups,"Let $G$ be a compact Lie group. In this article, we investigate the Cauchy
problem for a nonlinear wave equation with the viscoelastic damping on $G$.
More preciously, we investigate some $L^2$-estimates for the solution to the
homogeneous nonlinear viscoelastic damped wave equation on $G$ utilizing the
group Fourier transform on $G$. We also prove that there is no improvement of
any decay rate for the norm $\|u(t,\cdot)\|_{L^2(G)}$ by further assuming the
$L^1(G)$-regularity of initial data. Finally, using the noncommutative Fourier
analysis on compact Lie groups, we prove a local in time existence result in
the energy space $\mathcal{C}^1([0,T],H^1_{\mathcal L}(G)).$",2207.06645v3
2022-08-04,Normal and Quasinormal Modes of Holographic Multiquark Star,"The quadrupole normal-mode oscillation frequency $f_{n}$ of multiquark star
are computed for $n=1-5$. At the transition from low to high density multiquark
in the core region, the first 2 modes jump to larger values, a distinctive
signature of the presence of the high-density core. When the star oscillation
couples with spacetime, gravitational waves~(GW) will be generated and the star
will undergo damped oscillation. The quasinormal modes~(QNMs) of the
oscillation are computed using two methods, direct scan and WKB, for QNMs with
small and large imaginary parts respectively. The small imaginary QNMs have
frequencies $1.5-2.6$ kHz and damping times $0.19-1.7$ secs for multiquark star
with mass $M=0.6-2.1 M_{\odot}$~(solar mass). The WKB QNMs with large imaginary
parts have frequencies $5.98-9.81$ kHz and damping times $0.13-0.46$ ms for
$M\simeq 0.3-2.1 M_{\odot}$. They are found to be the fluid $f-$modes and
spacetime curvature $w-$modes respectively.",2208.02761v2
2022-08-10,Erasure qubits: Overcoming the $T_1$ limit in superconducting circuits,"The amplitude damping time, $T_1$, has long stood as the major factor
limiting quantum fidelity in superconducting circuits, prompting concerted
efforts in the material science and design of qubits aimed at increasing $T_1$.
In contrast, the dephasing time, $T_{\phi}$, can usually be extended above
$T_1$ (via, e.g., dynamical decoupling), to the point where it does not limit
fidelity. In this article we propose a scheme for overcoming the conventional
$T_1$ limit on fidelity by designing qubits in a way that amplitude damping
errors can be detected and converted into erasure errors. Compared to standard
qubit implementations our scheme improves the performance of fault-tolerant
protocols, as numerically demonstrated by the circuit-noise simulations of the
surface code. We describe two simple qubit implementations with superconducting
circuits and discuss procedures for detecting amplitude damping errors,
performing entangling gates, and extending $T_\phi$. Our results suggest that
engineering efforts should focus on improving $T_\phi$ and the quality of
quantum coherent control, as they effectively become the limiting factor on the
performance of fault-tolerant protocols.",2208.05461v1
2022-08-12,Critical exponent for nonlinear wave equations with damping and potential terms,"The aim of this paper is to determine the critical exponent for the nonlinear
wave equations with damping and potential terms of the scale invariant order,
by assuming that these terms satisfy a special relation. We underline that our
critical exponent is different from the one for related equations such as the
nonlinear wave equation without lower order terms, only with a damping term,
and only with a potential term. Moreover, we study the effect of the decaying
order of initial data at spatial infinity. In fact, we prove that not only the
lower order terms but also the order of the initial data affects the critical
exponent, as well as the sharp upper and lower bounds of the maximal existence
time of the solution.",2208.06106v3
2022-08-17,Conservation laws and variational structure of damped nonlinear wave equations,"All low-order conservation laws are found for a general class of nonlinear
wave equations in one dimension with linear damping which is allowed to be
time-dependent. Such equations arise in numerous physical applications and have
attracted much attention in analysis. The conservation laws describe
generalized momentum and boost momentum, conformal momentum, generalized
energy, dilational energy, and light-cone energies. Both the conformal momentum
and dilational energy have no counterparts for nonlinear undamped wave
equations in one dimension. All of the conservation laws are obtainable through
Noether's theorem, which is applicable because the damping term can be
transformed into a time-dependent self-interaction term by a change of
dependent variable. For several of the conservation laws, the corresponding
variational symmetries have a novel form which is different than any of the
well known variation symmetries admitted by nonlinear undamped wave equations
in one dimension.",2208.08026v2
2022-08-27,Impact of the free-streaming neutrinos to the second order induced gravitational waves,"The damping effect of the free-streaming neutrinos on the second order
gravitational waves is investigated in detail. We solve the Boltzmann equation
and give the anisotropic stress induced by neutrinos to second order. The first
order tensor and its coupling with scalar perturbations induced gravitational
waves are considered. We give the analytic equations of the damping kernel
functions and finally obtain the energy density spectrum. The results show that
the free-streaming neutrinos suppress the density spectrum significantly for
low frequency gravitational waves and enlarge the logarithmic slope $n$ in the
infrared region ($k \ll k_*$) of the spectrum. For the spectrum of $k_*\sim
10^{-7}$Hz, the damping effect in the range of $k<k_*$ is significant. The
combined effect of the first and second order could reduce the amplitude by
$30\%$ and make $n$ jump from $1.54$ to $1.63$ at $k\sim 10^{-9}$Hz, which may
be probed by the pulsar timing arrays (PTA) in the future.",2208.12948v1
2022-08-28,The small mass limit for long time statistics of a stochastic nonlinear damped wave equation,"We study the long time statistics of a class of semi--linear damped wave
equations with polynomial nonlinearities and perturbed by additive Gaussian
noise in dimensions 2 and 3. We find that if sufficiently many directions in
the phase space are stochastically forced, the system is exponentially
attractive toward its unique invariant measure with a convergent rate that is
uniform with respect to the mass. Then, in the small mass limit, we prove the
convergence of the first marginal of the invariant measures in a suitable
Wasserstein distance toward the unique invariant measure of a stochastic
reaction--diffusion equation. This together with uniform geometric ergodcity
implies the validity of the small mass limit for the solutions on the infinite
time horizon $[0,\infty)$, thereby extending previously known results
established for the damped wave equations under Lipschitz nonlinearities.",2208.13287v2
2022-08-30,Results on high energy galactic cosmic rays from the DAMPE space mission,"DAMPE (Dark Matter Particle Explorer) is a satellite-born experiment launched
in 2015 in a sun-synchronous orbit at 500 km altitude, and it has been taking
data in stable conditions ever since. Its main goals include the spectral
measurements up to very high energies, cosmic electrons/positrons and gamma
rays up to tens of TeV, and protons and nuclei up to hundreds of TeV. The
detector's main features include the 32 radiation lengths deep calorimeter and
large geometric acceptance, making DAMPE one of the most powerful space
instruments in operation, covering with high statistics and small systematics
the high energy frontier up to several hundreds TeV. The results of spectral
measurements of different species are shown and discussed.",2208.14300v2
2022-09-05,Generation and routing of nanoscale droplet solitons without compensation of magnetic damping,"Magnetic droplet soliton is a localized dynamic spin state which can serve as
a nanoscale information carrier and nonlinear oscillator. The present opinion
is that the formation of droplet solitons requires the compensation of magnetic
damping by a torque created by a spin-polarized electric current or pure spin
current. Here we demonstrate theoretically that nanoscale droplet solitons can
be generated and routed in ferromagnetic nanostructures with voltage-controlled
magnetic anisotropy in the presence of uncompensated magnetic damping.
Performing micromagnetic simulations for the MgO/Fe/MgO trilayer with almost
perpendicular-to-plane magnetization, we reveal the formation of the droplet
soliton under a nanoscale gate electrode subjected to a sub-nanosecond voltage
pulse. The soliton lives up to 50 ns at room temperature and can propagate over
micrometer distances in a ferromagnetic waveguide due to nonzero gradient of
the demagnetizing field. Furthermore, we show that an electrical routing of the
soliton to different outputs of a spintronic device can be realized with the
aid of an additional semiconducting nanostripe electrode creating controllable
gradient of the perpendicular magnetic anisotropy.",2209.01893v1
2022-09-06,Emergence of damped-localized excitations of the Mott state due to disorder,"A key aspect of ultracold bosonic quantum gases in deep optical lattice
potential wells is the realization of the strongly interacting Mott insulating
phase. Many characteristics of this phase are well understood, however little
is known about the effects of a random external potential on its gapped
quasiparticle and quasihole low-energy excitations. In the present study we
investigate the effect of disorder upon the excitations of the Mott insulating
state at zero temperature described by the Bose-Hubbard model. Using a
field-theoretical approach we obtain a resummed expression for the disorder
ensemble average of the spectral function. Its analysis shows that disorder
leads to an increase of the effective mass of both quasiparticle and quasihole
excitations. Furthermore, it yields the emergence of damped states, which
exponentially decay during propagation in space and dominate the whole band
when disorder becomes comparable to interactions. We argue that such
damped-localized states correspond to single-particle excitations of the
Bose-glass phase.",2209.02435v2
2022-09-21,Asymptotic profile of L^2-norm of solutions for wave equations with critical log-damping,"We consider wave equations with a special type of log-fractional damping. We
study the Cauchy problem for this model in the whole space, and we obtain an
asymptotic profile and optimal estimates of solutions as time goes to infinity
in L^2-sense. A maximal discovery of this note is that under the effective
damping, in case of n = 1 L^2-norm of the solution blows up in infinite time,
and in case of n = 2 L^2-norm of the solution never decays and never blows up
in infinite time. The latter phenomenon seems to be a rare case.",2209.10154v2
2022-09-25,Origin of Immediate Damping of Coherent Oscillations in Photoinduced Charge Density Wave Transition,"In stark contrast to the conventional charge density wave (CDW) materials,
the one-dimensional CDW on the In/Si(111) surface exhibits immediate damping of
the CDW oscillation during the photoinduced phase transition. Here, by
successfully reproducing the experimentally observed photoinduced CDW
transition on the In/Si(111) surface by performing real-time time-dependent
density functional theory (rt-TDDFT) simulations, we demonstrate that
photoexcitation promotes valence electrons from Si substrate to empty surface
bands composed primarily of the covalent p-p bonding states of the long In-In
bonds, generating interatomic forces to shorten the long bonds and in turn
drives coherently the structural transition. We illustrate that after the
structural transition, the component of these surface bands occurs a switch
among different covalent In bonds, causing a rotation of the interatomic forces
by about {\pi}/6 and thus quickly damping the oscillations in feature CDW
modes. These findings provide a deeper understanding of photoinduced phase
transitions.",2209.12135v1
2022-10-11,QKD in the NISQ era: enhancing secure key rates via quantum error correction,"Error mitigation is one of the key challenges in realising the full potential
of quantum cryptographic protocols. Consequently, there is a lot of interest in
adapting techniques from quantum error correction (QEC) to improve the
robustness of quantum cryptographic protocols. In this work, we benchmark the
performance of different QKD protocols on noisy quantum devices, with and
without error correction. We obtain the secure key rates of BB84, B92 and BBM92
QKD protocols over a quantum channel that is subject to amplitude-damping
noise. We demonstrate, theoretically and via implementations on the IBM quantum
processors, that B92 is the optimal protocol under amplitude-damping and
generalized amplitude-damping noise. We then show that the security of the
noisy BBM92 protocol crucially depends on the type and the mode of distribution
of an entangled pair. Finally, we implement an error-corrected BB84 protocol
using dual-rail encoding on a noisy quantum processor, and show that the
dual-rail BB84 implementation outperforms the conventional BB84 in the presence
of noise. Our secure key rate calculation also takes into account the effects
of CNOT imperfections on the error rates of the protocols.",2210.05297v1
2022-10-17,"Engineering imaginary stark ladder in a dissipative lattice: passive $\mathcal{PT}$ symmetry, K symmetry and localized damping","We study an imaginary stark ladder model and propose a realization of the
model in a dissipative chain with linearly increasing site-dependent
dissipation strength. Due to the existence of a $K$-symmetry and passive
$\mathcal{PT}$ symmetry, the model exhibits quite different feature from its
Hermitian counterpart. With the increase of dissipation strength, the system
first undergoes a passive $\mathcal{PT}$-symmetry breaking transition, with the
shifted eigenvalues changing from real to complex, and then a $K$-symmetry
restoring transition, characterized by the emergence of pure imaginary spectrum
with equal spacing. Accordingly, the eigenstates change from
$\mathcal{PT}$-unbroken extended states to the $\mathcal{PT}$-broken states,
and finally to stark localized states. In the framework of the quantum open
system governed by Lindblad equation with linearly increasing site-dependent
dissipation, we unveil that the dynamical evolution of single particle
correlation function is governed by the Hamiltonian of the imaginary stark
ladder model. By studying the dynamical evolution of the density distribution
under various initial states, we demonstrate that the damping dynamics displays
distinct behaviors in different regions. A localized damping is observed in the
strong dissipation limit.",2210.08725v3
2022-10-18,A quasi-local inhomogeneous dielectric tensor for arbitrary distribution functions,"Treatments of plasma waves usually assume homogeneity, but the parallel
gradients ubiquitous in plasmas can modify wave propagation and absorption. We
derive a quasilocal inhomogeneous correction to the plasma dielectric for
arbitrary distributions by expanding the phase correlation integral and develop
a novel integration technique that allows our correction to be applied in many
situations and has greater accuracy than other inhomogeneous dielectric
formulas found in the literature. We apply this dielectric tensor to the
lower-hybrid current drive problem and demonstrate that inhomogeneous wave
damping does not affect the lower-hybrid wave's linear damping condition, and
in the non-Maxwellian problem damping and propagation should remain unchanged
except in the case of waves with very large phase velocities.",2210.10214v1
2022-11-04,On the collisional damping of plasma velocity space instabilities,"For plasma velocity space instabilities driven by particle distributions
significantly deviated from a Maxwellian, weak collisions can damp the
instabilities by an amount that is significantly beyond the collisional rate
itself. This is attributed to the dual role of collisions that tend to relax
the plasma distribution toward a Maxwellian and to suppress the linearly
perturbed distribution function. The former effect can dominate in cases where
the unstable non-Maxwellian distribution is driven by collisionless transport
on a time scale much shorter than that of collisions, and the growth rate of
the ideal instability has a sensitive dependence on the distribution function.
The whistler instability driven by electrostatically trapped electrons is used
as an example to elucidate such a strong collisional damping effect of plasma
velocity space instabilities, which is confirmed by first-principles kinetic
simulations.",2211.02723v3
2022-11-12,Exponential Stability and exact controllability of a system of coupled wave equations by second order terms (via Laplacian) with only one non-smooth local damping,"The purpose of this work is to investigate the exponential stability of a
second order coupled wave equations by laplacian with one locally internal
viscous damping. Firstly, using a unique continuation theorem combined with a
Carleman estimate, we prove that our system is strongly stable without any
geometric condition. Secondly, using a combination of the multiplier techniques
and the frequency domain approach, we show that our system is exponentially
stable under \textbf{(PMGC)} condition on the damping region without any
restriction on wave propagation speed (i.e whether the two wave equations
propagate at the same speed or not)",2211.06706v2
2022-11-10,Generalized Bagley-Torvik Equation and Fractional Oscillators,"In this paper the Bagley-Torvik Equation is considered with the order of the
damping term allowed to range between one and two. The solution is found to be
representable as a convolution of trigonometric and exponential functions with
the driving force. The properties of the effective decay rate and the
oscillation frequency with respect to the order of the fractional damping are
also studied. It is found that the effective decay rate and oscillation
frequency have a complex dependency on the order of the derivative of the
damping term and exhibit properties one might expect of a thermodynamic
Equation of state: critical point, phase change, and lambda transition.",2211.07575v1
2022-11-21,Lifespan estimates for the compressible Euler equations with damping via Orlicz spaces techniques,"In this paper we are interested in the upper bound of the lifespan estimate
for the compressible Euler system with time dependent damping and small initial
perturbations. We employ some techniques from the blow-up study of nonlinear
wave equations. The novelty consists in the introduction of tools from the
Orlicz spaces theory to handle the nonlinear term emerging from the pressure $p
\equiv p(\rho)$, which admits different asymptotic behavior for large and small
values of $\rho-1$, being $\rho$ the density. Hence we can establish, in high
dimensions $n\in\{2,3\}$, unified upper bounds of the lifespan estimate
depending only on the dimension $n$ and on the damping strength, and
independent of the adiabatic index $\gamma>1$. We conjecture our results to be
optimal. The method employed here not only improves the known upper bounds of
the lifespan for $n\in\{2,3\}$, but has potential application in the study of
related problems.",2211.11377v1
2022-11-23,The fractional Landau-Lifshitz-Gilbert equation,"The dynamics of a magnetic moment or spin are of high interest to
applications in technology. Dissipation in these systems is therefore of
importance for improvement of efficiency of devices, such as the ones proposed
in spintronics. A large spin in a magnetic field is widely assumed to be
described by the Landau-Lifshitz-Gilbert (LLG) equation, which includes a
phenomenological Gilbert damping. Here, we couple a large spin to a bath and
derive a generic (non-)Ohmic damping term for the low-frequency range using a
Caldeira-Leggett model. This leads to a fractional LLG equation, where the
first-order derivative Gilbert damping is replaced by a fractional derivative
of order $s \ge 0$. We show that the parameter $s$ can be determined from a
ferromagnetic resonance experiment, where the resonance frequency and linewidth
no longer scale linearly with the effective field strength.",2211.12889v1
2022-11-24,A brief introduction to the mathematics of Landau damping,"In these short, rather informal, expository notes I review the current state
of the field regarding the mathematics of Landau damping, based on lectures
given at the CIRM Research School on Kinetic Theory, November 14--18, 2022.
These notes are mainly on Vlasov-Poisson in $(x,v) \in \mathbb T^d \times
\mathbb R^d$ however a brief discussion of the important case of $(x,v) \in
\mathbb R^d \times \mathbb R^d$ is included at the end. The focus will be
nonlinear and these notes include a proof of Landau damping on $(x,v) \in
\mathbb T^d \times \mathbb R^d$ in the Vlasov--Poisson equations meant for
graduate students, post-docs, and others to learn the basic ideas of the
methods involved. The focus is also on the mathematical side, and so most
references are from the mathematical literature with only a small number of the
many important physics references included. A few open problems are included at
the end.
  These notes are not currently meant for publication so they may not be
perfectly proof-read and the reference list might not be complete. If there is
an error or you have some references which you think should be included, feel
free to send me an email and I will correct it when I get a chance.",2211.13707v1
2022-12-04,Vibration suppression of a state-of-the-art wafer gripper,"In this paper the implementation of piezoelectrics to a state-of-the-art
wafer gripper is investigated. The objective is to propose and validate a
solution method, which includes a mechanical design and control system, to
achieve at least 5% damping for two eigenmodes of a wafer gripper. This
objective serves as a 'proof of concept' to show the possibilities of
implementing a state-of-the-art damping method to an industrial application,
which in turn can be used to dampen different thin structures. The coupling
relation between the piezoelectrics and their host structure were used to
design the placement of the piezoelectric patches, together with modal analysis
data of the a state-of-the-art wafer gripper. This data had been measured
through an experimental setup. Active damping has been succesfully implemented
onto the wafer gripper where positive position feedback (PPF) is used as a
control algorithm to dampen two eigenmodes.",2212.01854v1
2022-12-20,Algebra of L-banded Matrices,"Convergence is a crucial issue in iterative algorithms. Damping is commonly
employed to ensure the convergence of iterative algorithms. The conventional
ways of damping are scalar-wise, and either heuristic or empirical. Recently,
an analytically optimized vector damping was proposed for memory
message-passing (iterative) algorithms. As a result, it yields a special class
of covariance matrices called L-banded matrices. In this paper, we show these
matrices have broad algebraic properties arising from their L-banded structure.
In particular, compact analytic expressions for the LDL decomposition, the
Cholesky decomposition, the determinant after a column substitution, minors,
and cofactors are derived. Furthermore, necessary and sufficient conditions for
an L-banded matrix to be definite, a recurrence to obtain the characteristic
polynomial, and some other properties are given. In addition, we give new
derivations of the determinant and the inverse. (It's crucial to emphasize that
some works have independently studied matrices with this special structure,
named as L-matrices. Specifically, L-banded matrices are regarded as L-matrices
with real and finite entries.)",2212.12431v3
2023-01-23,Non-Markovianity in the time evolution of open quantum systems assessed by means of quantum state distance,"We provide a quantitative evaluation of non-Markovianity (NM) for an XX chain
of interacting qubits with one end coupled to a reservoir. The NM of several
non-Markovian spectral densities is assessed in terms of various quantum state
distance (QSD) measures. Our approach is based on the construction of the
density matrix of the open chain, without the necessity of a master equation.
For the quantification of NM we calculate the dynamics of the QSD measures
between the Markovian-damped and various types of non-Markovian-damped cases.
Since in the literature several QSD measures, appear in forms that imply trace
preserving density matrices, we introduced appropriate modifications so as to
render them applicable to the case of decaying traces. The results produce
remarkable consistency between the various QSD measures. They also reveal a
subtle and potentially useful interplay between qubit-qubit interaction and
non-Markovian damping. Our calculations have also uncovered a surprisingly
dramatic slowing-down of dissipation by the squared Lorentzian reservoir.",2301.09323v2
2023-01-26,Optimisation of Power Grid Stability Under Uncertainty,"The increased integration of intermittent and decentralised forms of power
production has eroded the stability margins of power grids and made it more
challenging to ensure reliable and secure power transmission. Reliable grid
operation requires system-scale stability in response to perturbations in
supply or load; previous studies have shown that this can be achieved by tuning
the effective damping parameters of the generators in the grid. In this paper,
we present and analyse the problem of tuning damping parameters when there is
some uncertainty in the underlying system. We show that sophisticated methods
that assume no uncertainty can yield results that are less robust than those
produced by simpler methods. We define a quantile-based metric of stability
that ensures that power grids remain stable even as worst-case scenarios are
approached, and we develop optimisation methods for tuning damping parameters
to achieve this stability. By comparing optimisation methods that rely on
different assumptions, we suggest efficient heuristics for finding parameters
that achieve highly stable and robust grids.",2301.11215v1
2023-02-11,Uniform stabilization for the semi-linear wave equation with nonlinear Kelvin-Voigt damping,"This paper is concerned with the decay estimate of solutions to the
semilinear wave equation subject to two localized dampings in a bounded domain.
The first one is of the nonlinear Kelvin-Voigt type and is distributed around a
neighborhood of the boundary according to the Geometric Control Condition.
While the second one is a frictional damping and we consider it hurting the
geometric condition of control. We show uniform decay rate results of the
corresponding energy for all initial data taken in bounded sets of finite
energy phase-space. The proof is based on obtaining an observability inequality
which combines unique continuation properties and the tools of the Microlocal
Analysis Theory.",2302.05667v1
2023-02-20,Exponentially stable breather solutions in nonautonomous dissipative nonlinear Schrödinger lattices,"We consider damped and forced discrete nonlinear Schr\""odinger equations on
the lattice $\mathbb{Z}$. First we establish the existence of periodic and
quasiperiodic breather solutions for periodic and quasiperiodic driving,
respectively. Notably, quasiperiodic breathers cannot exist in the system
without damping and driving. Afterwards the existence of a global uniform
attractor for the dissipative dynamics of the system is shown. For strong
dissipation we prove that the global uniform attractor has finite fractal
dimension and consists of a single trajectory that is confined to a finite
dimensional subspace of the infinite dimensional phase space, attracting any
bounded set in phase space exponentially fast. Conclusively, for strong damping
and periodic (quasiperiodic) forcing the single periodic (quasiperiodic)
breather solution possesses a finite number of modes and is exponentially
stable.",2302.09869v2
2023-02-11,"Quasinormal modes, Hawking radiation and absorption of the massless scalar field for Bardeen black hole surrounded by perfect fluid dark matter","Bardeen black hole surrounded by perfect fluid dark matter for a massless
scalar field. Our result shows that the oscillation frequency of quasinormal
modes is enhanced as magnetic charge $g$ or the dark matter parameter $\alpha$
increases. For damping rate of quasinormal modes, the influence of them is
different. Specifically, the increase of dark matter parameter $\alpha$ makes
the damping rate increasing at first and then decreasing. While the damping
rate is continuously decreasing with the increase of the magnetic charge $g$.
Moreover, we find that the increase of the dark matter parameter $\alpha$
enhances the power emission spectrum whereas magnetic charge $g$ suppresses it.
This means that the lifespan of black holes increases for smaller value of
$\alpha$ and larger value of $g$ when other parameters are fixed. Finally, the
absorption cross section of the considered black hole is calculated with the
help of the partial wave approach. Our result suggests that the absorption
cross section decreases with the dark matter $\alpha$ or the magnetic charge
$g$ increasing.",2302.10758v1
2023-02-24,A Numerical Approach for Modeling the Shunt Damping of Thin Panels with Arrays of Separately Piezoelectric Patches,"Two-dimensional thin plates are widely used in many aerospace and automotive
applications. Among many methods for the attenuation of vibration of these
mechanical structures, piezoelectric shunt damping is a promising way. It
enables a compact vibration damping method without adding significant mass and
volumetric occupancy. Analyzing the dynamics of these electromechanical systems
requires precise modeling tools that properly consider the coupling between the
piezoelectric elements and the host structure. This paper presents a
methodology for separately shunted piezoelectric patches for achieving higher
performance on vibration attenuation. The Rayleigh-Ritz method is used for
performing the modal analysis and obtaining the frequency response functions of
the electro-mechanical system. The effectiveness of the method is investigated
for a broader range of frequencies, and it was shown that separately shunted
piezoelectric patches are more effective.",2302.12525v1
2023-02-27,"Enhancing quantum synchronization through homodyne measurement, noise and squeezing","Quantum synchronization has been a central topic in quantum nonlinear
dynamics. Despite rapid development in this field, very few have studied how to
efficiently boost synchronization. Homodyne measurement emerges as one of the
successful candidates for this task, but preferably in the semi-classical
regime. In our work, we focus on the phase synchronization of a harmonic-driven
quantum Stuart-Landau oscillator, and show that the enhancement induced by
homodyne measurement persists into the quantum regime. Interestingly, optimal
two-photon damping rates exist when the oscillator and driving are at resonance
and with a small single-photon damping rate. We also report noise-induced
enhancement in quantum synchronization when the single-photon damping rate is
sufficiently large. Apart from these results, we discover that adding a
squeezing Hamiltonian can further boost synchronization, especially in the
semi-classical regime. Furthermore, the addition of squeezing causes the
optimal two-photon pumping rates to shift and converge.",2302.13465v2
2023-03-06,Larmor precession in strongly correlated itinerant electron systems,"Many-electron systems undergo a collective Larmor precession in the presence
of a magnetic field. In a paramagnetic metal, the resulting spin wave provides
insight into the correlation effects generated by the electron-electron
interaction. Here, we use dynamical mean-field theory to investigate the
collective Larmor precession in the strongly correlated regime, where dynamical
correlation effects such as quasiparticle lifetimes and non-quasiparticle
states are essential. We study the spin excitation spectrum, which includes a
dispersive Larmor mode as well as electron-hole excitations that lead to Stoner
damping. We also extract the momentum-resolved damping of slow spin waves. The
accurate theoretical description of these phenomena relies on the Ward
identity, which guarantees a precise cancellation of self-energy and vertex
corrections at long wavelengths. Our findings pave the way towards a better
understanding of spin wave damping in correlated materials.",2303.03468v2
2023-03-19,Asymptotic-preserving finite element analysis of Westervelt-type wave equations,"Motivated by numerical modeling of ultrasound waves, we investigate robust
conforming finite element discretizations of quasilinear and possibly nonlocal
equations of Westervelt type. These wave equations involve either a strong
dissipation or damping of fractional-derivative type and we unify them into one
class by introducing a memory kernel that satisfies non-restrictive regularity
and positivity assumptions. As the involved damping parameter is relatively
small and can become negligible in certain (inviscid) media, it is important to
develop methods that remain stable as the said parameter vanishes. To this end,
the contributions of this work are twofold. First, we determine sufficient
conditions under which conforming finite element discretizations of (non)local
Westervelt equations can be made robust with respect to the dissipation
parameter. Secondly, we establish the rate of convergence of the semi-discrete
solutions in the singular vanishing dissipation limit. The analysis hinges upon
devising appropriate energy functionals for the semi-discrete solutions that
remain uniformly bounded with respect to the damping parameter.",2303.10743v1
2023-03-31,Measurement of the cosmic p+He energy spectrum from 46 GeV to 316 TeV with the DAMPE space mission,"Recent observations of the light component of the cosmic-ray spectrum have
revealed unexpected features that motivate further and more precise
measurements up to the highest energies. The Dark Matter Particle Explorer
(DAMPE) is a satellite-based cosmic-ray experiment that is operational since
December 2015, continuously collecting data on high-energy cosmic particles
with very good statistics, energy resolution, and particle identification
capabilities. In this work, the latest measurements of the energy spectrum of
proton+helium in the energy range from 46 GeV to 316 TeV are presented. Among
the most distinctive features of the spectrum, a spectral hardening at
$\sim$600 GeV has been observed, along with a softening at $\sim$29 TeV
measured with a 6.6$\sigma$ significance. Moreover, by measuring the energy
spectrum up to 316 TeV, a strong link is established between space- and
ground-based experiments, also suggesting the presence of a second hardening at
$\sim$150 TeV.",2304.00137v4
2023-04-18,Edge-selective extremal damping from topological heritage of dissipative Chern insulators,"One of the most important practical hallmarks of topological matter is the
presence of topologically protected, exponentially localised edge states at
interfaces of regions characterised by unequal topological invariants. Here, we
show that even when driven far from their equilibrium ground state, Chern
insulators can inherit topological edge features from their parent Hamiltonian.
In particular, we show that the asymptotic long-time approach of the
non-equilibrium steady state, governed by a Lindblad Master equation, can
exhibit edge-selective extremal damping. This phenomenon derives from edge
states of non-Hermitian extensions of the parent Chern insulator Hamiltonian.
The combination of (non-Hermitian) topology and dissipation hence allows to
design topologically robust, spatially localised damping patterns.",2304.09040v3
2023-04-25,Weakly damped bosons and precursor gap in the vicinity of an antiferromagnetic metallic transition,"We study the electronic spectral function of a metal in the vicinity of an
antiferromagnetic (AFM) quantum critical point, focusing on a situation where
the bare bandwidth of the spin fluctuations is significantly smaller than the
Fermi energy. In this limit, we identify a range of energies where the
fermionic quasiparticles near the ""hot spots'' on the Fermi surface are
strongly scattered by the quantum critical fluctuations, whereas the damping of
the AFM fluctuations by the electrons is negligible. Within a one-loop
approximation, there is a parameter range where the $T=0$ spectral function at
the hot spots has a ""precursor gap'' feature, with a local maximum at a finite
frequency. However, the ratio of the bare spin wave velocity to the Fermi
velocity required to obtain a precursor gap is probably too small to explain
experiments in the electron-doped cuprate superconductors (He et al., Proc.
Natl. Acad. Sci 116, 3449 (2019)). At lower frequencies, the Landau damping of
the AFM fluctuations becomes important, and the electronic spectral function
has the familiar ${\omega}^{-1/2}$ singularity. Our one-loop perturbative
results are supported by a numerical Monte Carlo simulation of electrons
coupled to an undamped, nearly-critical AFM mode.",2304.12697v1
2023-05-06,Stochastic wave equation with Hölder noise coefficient: well-posedness and small mass limit,"We construct unique martingale solutions to the damped stochastic wave
equation $$ \mu \frac{\partial^2u}{\partial t^2}(t,x)=\Delta
u(t,x)-\frac{\partial u}{\partial
t}(t,x)+b(t,x,u(t,x))+\sigma(t,x,u(t,x))\frac{dW_t}{dt},$$
  where $\Delta$ is the Laplacian on $[0,1]$ with Dirichlet boundary condition,
$W$ is space-time white noise, $\sigma$ is $\frac{3}{4}+\epsilon$ -H\""older
continuous in $u$ and uniformly non-degenerate, and $b$ has linear growth. The
same construction holds for the stochastic wave equation without damping term.
More generally, the construction holds for SPDEs defined on separable Hilbert
spaces with a densely defined operator $A$, and the assumed H\""older regularity
on the noise coefficient depends on the eigenvalues of $A$ in a quantitative
way. We further show the validity of the Smoluchowski-Kramers approximation:
assume $b$ is H\""older continuous in $u$, then as $\mu$ tends to $0$ the
solution to the damped stochastic wave equation converges in distribution, on
the space of continuous paths, to the solution of the corresponding stochastic
heat equation. The latter result is new even in the case of additive noise.",2305.04068v2
2023-05-08,Information capacity analysis of fully correlated multi-level amplitude damping channels,"The primary objective of quantum Shannon theory is to evaluate the capacity
of quantum channels. In spite of the existence of rigorous coding theorems that
quantify the transmission of information through quantum channels,
superadditivity effects limit our understanding of the channel capacities. In
this paper, we mainly focus on a family of channels known as multi-level
amplitude damping channels. We investigate some of the information capacities
of the simplest member of multi-level Amplitude Damping Channel, a qutrit
channel, in the presence of correlations between successive applications of the
channel. We find the upper bounds of the single-shot classical capacities and
calculate the quantum capacities associated with a specific class of maps after
investigating the degradability property of the channels. Additionally, the
quantum and classical capacities of the channels have been computed in
entanglement-assisted scenarios.",2305.04481v2
2023-05-09,Lifespan estimates for semilinear damped wave equation in a two-dimensional exterior domain,"Lifespan estimates for semilinear damped wave equations of the form
$\partial_t^2u-\Delta u+\partial_tu=|u|^p$ in a two dimensional exterior domain
endowed with the Dirichlet boundary condition are dealt with. For the critical
case of the semilinear heat equation $\partial_tv-\Delta v=v^2$ with the
Dirichlet boundary condition and the initial condition $v(0)=\varepsilon f$,
the corresponding lifespan can be estimated from below and above by
$\exp(\exp(C\varepsilon^{-1}))$ with different constants $C$. This paper
clarifies that the same estimates hold even for the critical semilinear damped
wave equation in the exterior of the unit ball under the restriction of radial
symmetry. To achieve this result, a new technique to control $L^1$-type norm
and a new Gagliardo--Nirenberg type estimate with logarithmic weight are
introduced.",2305.05124v1
2023-05-19,Cold damping of levitated optically coupled nanoparticles,"Methods for controlling the motion of single particles, optically levitated
in vacuum, have developed rapidly in recent years. The technique of cold
damping makes use of feedback-controlled, electrostatic forces to increase
dissipation without introducing additional thermal fluctuations. This process
has been instrumental in the ground-state cooling of individual electrically
charged nanoparticles. Here we show that the same method can be applied to a
pair of nanoparticles, coupled by optical binding forces. These optical binding
forces are about three orders of magnitude stronger than typical Coulombic
inter-particle force and result in a coupled motion of both nanoparticles
characterized by a pair of normal modes. We demonstrate cold damping of these
normal modes, either independently or simultaneously, to sub-Kelvin
temperatures at pressures of 5x10^{-3} mbar. Experimental observations are
captured by a theoretical model which we use to survey the parameter space more
widely and to quantify the limits imposed by measurement noise and time delays.
Our work paves the way for the study of quantum interactions between meso-scale
particles and the exploration of multiparticle entanglement in levitated
optomechanical systems.",2305.11809v1
2023-05-25,Damping of three-dimensional waves on coating films dragged by moving substrates,"Paints and coatings often feature interfacial defects due to disturbances
during the deposition process which, if they persist until solidification,
worsen the product quality. In this article, we investigate the stability of a
thin liquid film dragged by a vertical substrate moving against gravity, a flow
configuration found in a variety of coating processes. The receptivity of the
liquid film to three-dimensional disturbances is discussed with Direct
Numerical Simulations (DNS), an in-house non-linear Integral Boundary Layer
(IBL) film model, and Linear Stability Analysis (LSA). The thin film model,
successfully validated with the DNS computations, implements a pseudo-spectral
approach for the capillary terms that allows for investigating non-periodic
surface tension dominated flows. The combination of these numerical tools
allows for describing the mechanisms of capillary and non-linear damping, and
identifying the instability threshold of the coating processes. The results
show that transverse modulations can be beneficial for the damping of
two-dimensional waves within the range of operational conditions considered in
this study, typical of air-knife and slot-die coating.",2305.16139v3
2023-06-12,Realizable Eddy Damped Markovian Anisotropic Closure for Turbulence and Rossby Wave Interactions,"A realizable Eddy Damped Markovian Anisotropic Closure (EDMAC) is presented
for the interaction of two dimensional turbulence and transient waves such as
Rossby waves. The structure of the EDMAC ensures that it is as computationally
efficient as the Eddy Damped Quasi Normal Markovian (EDQNM) closure but unlike
the EDQNM is guaranteed to be realizable in the presence of transient waves.
Jack Herring's important contributions to laying the foundations of statistical
dynamical closure theories of fluid turbulence are briefly reviewed. The topics
covered include equilibrium statistical mechanics, Eulerian and Lagrangian
statistical dynamical closure theories, and the statistical dynamics of the
interaction of turbulence with topography. The impact of Herring's work is
described and placed in the context of related developments. Some of the
further works that have built on Herring's foundations are discussed. The
relationships between theoretical approaches employed in statistical classical
and quantum field theories, and their overlap, are outlined. The seminal
advances made by the pioneers in strong interaction fluid turbulence are put
into perspective by comparing related developments in strong interaction
quantum filed theory.",2306.06921v1
2023-06-18,Partial data inverse problem for hyperbolic equation with time-dependent damping coefficient and potential,"We study an inverse problem of determining a time-dependent damping
coefficient and potential appearing in the wave equation in a compact
Riemannian manifold of dimension three or higher. More specifically, we are
concerned with the case of conformally transversally anisotropic manifolds, or
in other words, compact Riemannian manifolds with boundary conformally embedded
in a product of the Euclidean line and a transversal manifold. With an
additional assumption of the attenuated geodesic ray transform being injective
on the transversal manifold, we prove that the knowledge of a certain partial
Cauchy data set determines time-dependent damping coefficient and potential
uniquely.",2306.10442v2
2023-06-26,"Blow-up result for a weakly coupled system of wave equations with a scale-invariant damping, mass term and time derivative nonlinearity","We study in this article the blow-up of solutions to a coupled semilinear
wave equations which are characterized by linear damping terms in the
\textit{scale-invariant regime}, time-derivative nonlinearities, mass terms and
Tricomi terms. The latter are specifically of great interest from both physical
and mathematical points of view since they allow the speeds of propagation to
be time-dependent ones. However, we assume in this work that both waves are
propagating with the same speeds. Employing this fact together with other
hypotheses on the aforementioned parameters (mass and damping coefficients), we
obtain a new blow-up region for the system under consideration, and we show a
lifespan estimate of the maximal existence time.",2306.14768v1
2023-06-26,Revisiting the damped quantum harmonic oscillator,"We reanalyse the quantum damped harmonic oscillator, introducing three less
than common features. These are (i) the use of a continuum model of the
reservoir rather than an ensemble of discrete oscillators, (ii) an exact
diagonalisation of the Hamiltonian by adapting a technique pioneered by Fano,
and (iii) the use of the thermofield technique for describing a finite
temperature reservoir. We recover in this way a number of well-known and some,
perhaps, less familiar results. An example of the latter is an ab initio proof
that the oscillator relaxes to the mean-force Gibbs state. We find that special
care is necessary when comparing the damped oscillator with its undamped
counterpart as the former has two distinct natural frequencies, one associated
with short time evolution and the other with longer times.",2306.15013v1
2023-06-27,SPDER: Semiperiodic Damping-Enabled Object Representation,"We present a neural network architecture designed to naturally learn a
positional embedding and overcome the spectral bias towards lower frequencies
faced by conventional implicit neural representation networks. Our proposed
architecture, SPDER, is a simple MLP that uses an activation function composed
of a sinusoidal multiplied by a sublinear function, called the damping
function. The sinusoidal enables the network to automatically learn the
positional embedding of an input coordinate while the damping passes on the
actual coordinate value by preventing it from being projected down to within a
finite range of values. Our results indicate that SPDERs speed up training by
10x and converge to losses 1,500-50,000x lower than that of the
state-of-the-art for image representation. SPDER is also state-of-the-art in
audio representation. The superior representation capability allows SPDER to
also excel on multiple downstream tasks such as image super-resolution and
video frame interpolation. We provide intuition as to why SPDER significantly
improves fitting compared to that of other INR methods while requiring no
hyperparameter tuning or preprocessing.",2306.15242v1
2023-07-03,Fast Convergence of Inertial Multiobjective Gradient-like Systems with Asymptotic Vanishing Damping,"We present a new gradient-like dynamical system related to unconstrained
convex smooth multiobjective optimization which involves inertial effects and
asymptotic vanishing damping. To the best of our knowledge, this system is the
first inertial gradient-like system for multiobjective optimization problems
including asymptotic vanishing damping, expanding the ideas laid out in [H.
Attouch and G. Garrigos, Multiobjective optimization: an inertial approach to
Pareto optima, preprint, arXiv:1506.02823, 201]. We prove existence of
solutions to this system in finite dimensions and further prove that its
bounded solutions converge weakly to weakly Pareto optimal points. In addition,
we obtain a convergence rate of order $O(t^{-2})$ for the function values
measured with a merit function. This approach presents a good basis for the
development of fast gradient methods for multiobjective optimization.",2307.00975v3
2023-07-05,Strong convergence rates for a full discretization of stochastic wave equation with nonlinear damping,"The paper establishes the strong convergence rates of a spatio-temporal full
discretization of the stochastic wave equation with nonlinear damping in
dimension one and two. We discretize the SPDE by applying a spectral Galerkin
method in space and a modified implicit exponential Euler scheme in time. The
presence of the super-linearly growing damping in the underlying model brings
challenges into the error analysis. To address these difficulties, we first
achieve upper mean-square error bounds, and then obtain mean-square convergence
rates of the considered numerical solution. This is done without requiring the
moment bounds of the full approximations. The main result shows that, in
dimension one, the scheme admits a convergence rate of order $\tfrac12$ in
space and order $1$ in time. In dimension two, the error analysis is more
subtle and can be done at the expense of an order reduction due to an
infinitesimal factor. Numerical experiments are performed and confirm our
theoretical findings.",2307.01975v1
2023-07-12,Decoherence effects on lepton number violation from heavy neutrino-antineutrino oscillations,"We study decoherence effects and phase corrections in heavy
neutrino-antineutrino oscillations (NNOs), based on quantum field theory with
external wave packets. Decoherence damps the oscillation pattern, making it
harder to resolve experimentally. Additionally, it enhances lepton number
violation (LNV) for processes in symmetry-protected low-scale seesaw models by
reducing the destructive interference between mass eigenstates. We discuss a
novel time-independent shift in the phase and derive formulae for calculating
decoherence effects and the phase shift in the relevant regimes, which are the
no dispersion regime and transverse dispersion regime. We find that the phase
shift can be neglected in the parameter region under consideration since it is
small apart from parameter regions with large damping. In the oscillation
formulae, decoherence can be included by an effective damping parameter. We
discuss this parameter and present averaged results, which apply to simulations
of NNOs in the dilepton-dijet channel at the HL-LHC. We show that including
decoherence effects can dramatically change the theoretical prediction for the
ratio of LNV over LNC events.",2307.06208v1
2023-07-23,Visco-elastic damped wave models with time-dependent coefficient,"In this paper, we study the following Cauchy problem for linear visco-elastic
damped wave models with a general time-dependent coefficient $g=g(t)$:
\begin{equation} \label{EqAbstract} \tag{$\star$} \begin{cases} u_{tt}- \Delta
u + g(t)(-\Delta)u_t=0, &(t,x) \in (0,\infty) \times \mathbb{R}^n, \\ u(0,x)=
u_0(x),\quad u_t(0,x)= u_1(x), &x \in \mathbb{R}^n. \end{cases} \end{equation}
We are interested to study the influence of the damping term $g(t)(-\Delta)u_t$
on qualitative properties of solutions to \eqref{EqAbstract} as decay estimates
for energies of higher order and the parabolic effect. The main tools are
related to WKB-analysis. We apply elliptic as well as hyperbolic WKB-analysis
in different parts of the extended phase space.",2307.12340v1
2023-07-24,Phonon damping in a 2D superfluid: insufficiency of Fermi's golden rule at low temperature,"It is generally accepted that the phonon gas of a superfluid always enters a
weak coupling regime at sufficiently low temperatures, whatever the strength of
the interactions between the underlying particles (constitutive of the
superfluid). Thus, in this limit, we should always be able to calculate the
damping rate of thermal phonons by applying Fermi's golden rule to the $H\_3$
Hamiltonian of cubic phonon-phonon coupling taken from quantum hydrodynamics,
at least in the case of a convex acoustic branch and in the collisionless
regime (where the eigenfrequency of the considered phonons remains much greater
than the gas thermalization rate). Using the many-body Green's function method,
we predict that, unexpectedly, this is not true in two dimensions, contrary to
the three-dimensional case. We confirm this prediction with classical
phonon-field simulations and a non-perturbative theory in $H\_3$, where the
fourth order is regularized by hand, giving a complex energy to the virtual
phonons of the four-phonon collisional processes. For a weakly interacting
fluid and a phonon mode in the long-wavelength limit, we predict a damping rate
about three times lower than that of the golden rule.",2307.12705v1
2023-08-01,Regularity for the Timoshenko system with fractional damping,"We study, the Regularity of the Timoshenko system with two fractional
dampings $(-\Delta)^\tau u_t$ and $(-\Delta)^\sigma \psi_t$; both of the
parameters $(\tau, \sigma)$ vary in the interval $[0,1]$. We note that
($\tau=0$ or $\sigma=0$) and ($\tau=1$ or $\sigma=1$) the dampings are called
frictional and viscous, respectively. Our main contribution is to show that the
corresponding semigroup $S(t)=e^{\mathcal{B}t}$, is analytic for
$(\tau,\sigma)\in R_A:=[1/2,1]\times[ 1/2,1]$ and determine the Gevrey's class
$\nu>\dfrac{1}{\phi}$, where $\phi=\left\{\begin{array}{ccc}
\dfrac{2\sigma}{\sigma+1} &{\rm for} & \sigma\leq \tau,\\\\
\dfrac{2\tau}{\tau+1} &{\rm for} & \tau\leq \sigma. \end{array}\right.$ \quad
and \quad $(\tau,\sigma)\in R_{CG}:= (0,1)^2$.",2308.00573v2
2023-09-06,Effective Description of the Quantum Damped Harmonic Oscillator: Revisiting the Bateman Dual System,"In this work, we present a quantization scheme for the damped harmonic
oscillator (QDHO) using a framework known as momentous quantum mechanics. Our
method relies on a semiclassical dynamical system derived from an extended
classical Hamiltonian, where the phase-space variables are given by expectation
values of observables and quantum dispersions. The significance of our study
lies in its potential to serve as a foundational basis for the effective
description of open quantum systems (OQS), and the description of dissipation
in quantum mechanics. By employing the Bateman's dual model as the initial
classical framework, and undergoing quantization, we demonstrate that our
description aligns exceptionally well with the well-established Lindblad master
equation. Furthermore, our approach exhibits robustness and broad applicability
in the context of OQS, rendering it a versatile and powerful tool for studying
various phenomena. We intend to contribute to the advancement of quantum
physics by providing an effective means of quantizing the damped harmonic
oscillator and shedding light on the behavior of open quantum systems.",2309.02689v1
2023-09-09,Secondary cosmic-ray nuclei in the model of Galactic halo with nonlinear Landau damping,"We employ our recent model of the cosmic-ray (CR) halo by Chernyshov et al.
(2022) to compute the Galactic spectra of stable and unstable secondary nuclei.
In this model, confinement of the Galactic CRs is entirely determined by the
self-generated Alfvenic turbulence whose spectrum is controlled by nonlinear
Landau damping. We analyze the physical parameters affecting propagation
characteristics of CRs, and estimate the best set of free parameters providing
accurate description of available observational data. We also show that
agreement with observations at lower energies may be further improved by taking
into account the effect of ion-neutral damping which operates near the Galactic
disk.",2309.04772v1
2023-09-20,On the damping of tidally driven oscillations,"Expansions in the oscillation modes of tidally perturbed bodies provide a
useful framework for representing tidally induced flows. However, recent work
has demonstrated that such expansions produce inaccurate predictions for
secular orbital evolution when mode damping rates are computed independently.
We explore the coupling of collectively driven modes by frictional and viscous
dissipation, in tidally perturbed bodies that are both non-rotating and rigidly
rotating. This exploration leads us to propose an alternative approach to
treating the damping of tidally driven oscillations that accounts for
dissipative mode coupling, but which does not require any information beyond
the eigenfunctions and eigenfrequencies of adiabatic modes.",2309.11502v1
2023-09-25,Linearly implicit exponential integrators for damped Hamiltonian PDEs,"Structure-preserving linearly implicit exponential integrators are
constructed for Hamiltonian partial differential equations with linear constant
damping. Linearly implicit integrators are derived by polarizing the polynomial
terms of the Hamiltonian function and portioning out the nonlinearly of
consecutive time steps. They require only a solution of one linear system at
each time step. Therefore they are computationally more advantageous than
implicit integrators. We also construct an exponential version of the
well-known one-step Kahan's method by polarizing the quadratic vector field.
These integrators are applied to one-dimensional damped Burger's,
Korteweg-de-Vries, and nonlinear Schr{\""o}dinger equations. Preservation of the
dissipation rate of linear and quadratic conformal invariants and the
Hamiltonian is illustrated by numerical experiments.",2309.14184v2
2023-10-12,Plasmon dispersion and Landau damping in the nonlinear quantum regime,"We study the dispersion properties of electron plasma waves, or plasmons,
which can be excited in quantum plasmas in the nonlinear regime. In order to
describe nonlinear electron response to finite amplitude plasmons, we apply the
Volkov approach to non-relativistic electrons. For that purpose, we use the
Schr\""odinger equation and describe the electron population of a quantum plasma
as a mixture of quantum states. Within the kinetic framework that we are able
to derive from the Volkov solutions, we discuss the role of the wave amplitude
on the nonlinear plasma response. Finally, we focus on the quantum properties
of nonlinear Landau damping and study the contributions of multi-plasmon
absorption and emission processes.",2310.08544v1
2023-10-29,Asymptotic profiles for the Cauchy problem of damped beam equation with two variable coefficients and derivative nonlinearity,"In this article we investigate the asymptotic profile of solutions for the
Cauchy problem of the nonlinear damped beam equation with two variable
coefficients: \[ \partial_t^2 u + b(t) \partial_t u - a(t) \partial_x^2 u +
\partial_x^4 u
  = \partial_x \left( N(\partial_x u) \right). \] In the authors' previous
article [17], the asymptotic profile of solutions for linearized problem ($N
\equiv 0$) was classified depending on the assumptions for the coefficients
$a(t)$ and $b(t)$ and proved the asymptotic behavior in effective damping
cases. We here give the conditions of the coefficients and the nonlinear term
in order that the solution behaves as the solution for the heat equation: $b(t)
\partial_t u - a(t) \partial_x^2 u=0$ asymptotically as $t \to \infty$.",2310.18878v1
2023-11-09,Landau Damping in an Electron Gas,"Material science methods aim at developing efficient computational schemes
for describing complex many-body effects and how they are revealed in
experimentally measurable properties. Bethe-Salpeter equation in the
self-consistent Hartree-Fock basis is often used for this purpose, and in this
paper we employ the real-frequency diagrammatic Monte Carlo framework for
solving the ladder-type Bethe-Salpeter equation for the 3-point vertex function
(and, ultimately, for the system's polarization) to study the effect of
electron-hole Coulomb scattering on Landau damping in the homogeneous electron
gas. We establish how this damping mechanism depends on the Coulomb parameter
$r_s$ and changes with temperature between the correlated liquid and thermal
gas regimes. In a broader context of dielectric response in metals, we also
present the full polarization and the typical dependence of the
exchange-correlation kernel on frequency at finite momentum and temperature
within the same computational framework.",2311.05611v2
2023-11-11,On asymptotic properties of solutions to $σ$-evolution equations with general double damping,"In this paper, we would like to consider the Cauchy problem for semi-linear
$\sigma$-evolution equations with double structural damping for any $\sigma\ge
1$. The main purpose of the present work is to not only study the asymptotic
profiles of solutions to the corresponding linear equations but also describe
large-time behaviors of globally obtained solutions to the semi-linear
equations. We want to emphasize that the new contribution is to find out the
sharp interplay of ``parabolic like models"" corresponding to $\sigma_1 \in
[0,\sigma/2)$ and ``$\sigma$-evolution like models"" corresponding to $\sigma_2
\in (\sigma/2,\sigma]$, which together appear in an equation. In this
connection, we understand clearly how each damping term influences the
asymptotic properties of solutions.",2311.06660v1
2023-11-18,The temperature dependent Boltzmann equation beyond local equilibrium assumption,"In this manuscript, we present a temperature dependent Boltzmann equation for
the particles transport through a environmental reservoir, where the
temperature refers to the equilibrium temperature of reservoir, a new damping
force and a inverse damping relaxation time are derived based on the classical
Boltzmann equation, which have obvious influence on the external force and the
relaxation time of transport particles. For comparison, we also define a
non-equilibrium temperature for the transport particle by its distribution
function out of equilibrium, which is different from the equilibrium
temperature of reservoir. There exist heat transfer between the transport
particle and the reservoir, because the whole transport particles are in
non-equilibrium state. Finally, we illustrate them by an example of
one-dimensional transport procedure, the damping force and the non-equilibrium
temperature defined by us are shown numerically.",2311.11028v1
2023-12-13,"Integrating Superregenerative Principles in a Compact, Power-Efficient NMR/NQR Spectrometer: A Novel Approach with Pulsed Excitation","We present a new approach to Nuclear Quadrupole Resonance (NQR)/Nuclear
Magnetic Resonance (NMR) spectroscopy, the Damp-Enhanced Superregenerative
Nuclear Spin Analyser (DESSA). This system integrates Superregenerative
principles with pulsed sample excitation and detection, offering significant
advancements over traditional Super-Regenerative Receivers (SRRs). Our approach
overcomes certain limitations associated with traditional Super-Regenerative
Receivers (SRRs) by integrating direct digital processing of the oscillator
response delay time (T$_d$) and an electronic damp unit to regulate the
excitation pulse decay time (T$_e$). The essence is combining pulsed excitation
with a reception inspired by, but distinct from, conventional SRRs. The damp
unit allows a rapid termination of the oscillation pulse and the initiation of
detection within microseconds, and direct digital processing avoids the need
for a second lower frequency which is used for quenching in a traditional SRRs,
thereby avoiding the formation of sidebands. We demonstrate the effectiveness
of DESSA on a \ch{NaClO3} sample containing the isotope Chlorine-35 where it
accurately detects the NQR signal with sub-kHz resolution.",2312.08491v1
2023-12-26,"Dynamical polarization function, plasmons, their damping and collective effects in semi-Dirac bands","We have calculated the dynamical polarization, plasmons and damping rates in
semi-Dirac bands (SDB's) with zero band gap and half-linear, half-parabolic
low-energy spectrum. The obtained plasmon dispersions are strongly anisotropic
and demonstrate some crucial features of both two-dimensional electron gas and
graphene. Such gapless energy dispersions lead to a localized area of undamped
and low-damped plasmons in a limited range of the frequencies and wave vectors.
The calculated plasmon branches demonstrate an increase of their energies for a
finite tilting of the band structure and a fixed Fermi level which could be
used as a signature of a specific tilted spectrum in a semi-Dirac band.",2312.16117v1
2024-01-01,Calculation of Gilbert damping and magnetic moment of inertia using torque-torque correlation model within ab initio Wannier framework,"Magnetization dynamics in magnetic materials are well described by the
modified semiclassical Landau-Lifshitz-Gilbert (LLG) equation, which includes
the magnetic damping $\alpha$ and the magnetic moment of inertia $\mathrm{I}$
tensors as key parameters. Both parameters are material-specific and physically
represent the time scales of damping of precession and nutation in
magnetization dynamics. $\alpha$ and $\mathrm{I}$ can be calculated quantum
mechanically within the framework of the torque-torque correlation model. The
quantities required for the calculation are torque matrix elements, the real
and imaginary parts of the Green's function and its derivatives. Here, we
calculate these parameters for the elemental magnets such as Fe, Co and Ni in
an ab initio framework using density functional theory and Wannier functions.
We also propose a method to calculate the torque matrix elements within the
Wannier framework. We demonstrate the effectiveness of the method by comparing
it with the experiments and the previous ab initio and empirical studies and
show its potential to improve our understanding of spin dynamics and to
facilitate the design of spintronic devices.",2401.00714v1
2024-01-09,Coherent errors in stabilizer codes caused by quasistatic phase damping,"Quantum error correction is a key challenge for the development of practical
quantum computers, a direction in which significant experimental progress has
been made in recent years. In solid-state qubits, one of the leading
information loss mechanisms is dephasing, usually modelled by phase flip
errors. Here, we introduce quasistatic phase damping, a more subtle error model
which describes the effect of Larmor frequency fluctuations due to 1/f noise.
We show how this model is different from a simple phase flip error model, in
terms of multi-cycle error correction. Considering the surface code, we provide
numerical evidence for an error threshold, in the presence of quasistatic phase
damping and readout errors. We discuss the implications of our results for spin
qubits and superconducting qubits.",2401.04530v2
2024-01-19,Composite learning backstepping control with guaranteed exponential stability and robustness,"Adaptive backstepping control provides a feasible solution to achieve
asymptotic tracking for mismatched uncertain nonlinear systems. However,
input-to-state stability depends on high-gain feedback generated by nonlinear
damping terms, and closed-loop exponential stability with parameter convergence
involves a stringent condition named persistent excitation (PE). This paper
proposes a composite learning backstepping control (CLBC) strategy based on
modular backstepping and high-order tuners to compensate for the transient
process of parameter estimation and achieve closed-loop exponential stability
without the nonlinear damping terms and the PE condition. A novel composite
learning mechanism that maximizes the staged exciting strength is designed for
parameter estimation, such that parameter convergence can be achieved under a
condition of interval excitation (IE) or even partial IE that is strictly
weaker than PE. An extra prediction error is employed in the adaptive law to
ensure the transient performance without nonlinear damping terms. The
exponential stability of the closed-loop system is proved rigorously under the
partial IE or IE condition. Simulations have demonstrated the effectiveness and
superiority of the proposed method in both parameter estimation and control
compared to state-of-the-art methods.",2401.10785v1
2024-01-23,Model-Free $δ$-Policy Iteration Based on Damped Newton Method for Nonlinear Continuous-Time H$\infty$ Tracking Control,"This paper presents a {\delta}-PI algorithm which is based on damped Newton
method for the H{\infty} tracking control problem of unknown continuous-time
nonlinear system. A discounted performance function and an augmented system are
used to get the tracking Hamilton-Jacobi-Isaac (HJI) equation. Tracking HJI
equation is a nonlinear partial differential equation, traditional
reinforcement learning methods for solving the tracking HJI equation are mostly
based on the Newton method, which usually only satisfies local convergence and
needs a good initial guess. Based upon the damped Newton iteration operator
equation, a generalized tracking Bellman equation is derived firstly. The
{\delta}-PI algorithm can seek the optimal solution of the tracking HJI
equation by iteratively solving the generalized tracking Bellman equation.
On-policy learning and off-policy learning {\delta}-PI reinforcement learning
methods are provided, respectively. Off-policy version {\delta}-PI algorithm is
a model-free algorithm which can be performed without making use of a priori
knowledge of the system dynamics. NN-based implementation scheme for the
off-policy {\delta}-PI algorithms is shown. The suitability of the model-free
{\delta}-PI algorithm is illustrated with a nonlinear system simulation.",2401.12882v1
2024-01-30,The nonlinear dynamic behavior of a Rubber-Layer Roller Bearing (RLRB) for vibration isolation,"In this paper, we study the dynamic behavior of a Rubber-Layer Roller Bearing
(RLRB) interposed between a spring-mass elemental superstructure and a
vibrating base. Thanks to the viscoelastic rolling contact between the rigid
rollers and the rubber layers, the RLRB is able to provide a nonlinear damping
behavior. The effect of the RLRB geometric and material parameters is
investigated under periodic base excitation, showing that both periodic and
aperiodic responses can be achieved. Specifically, since the viscoelastic
damping is non-monotonic (bell shaped), there exist systemdynamic conditions
involving the decreasing portion of the damping curve in which a strongly
nonlinear behavior is experienced. In the second part of the paper, we
investigate the effectiveness of the nonlinear device in terms of seismic
isolation. Focusing on the mean shock of the Central Italy 2016 earthquake, we
opportunely tune the material and geometrical RLRB parameters, showing that a
significant reduction of both the peak and root-mean-square value of the
inertial force acting on the superstructure is achieved, compared to the best
performance of a linear base isolation system.",2401.16880v1
2024-01-30,Poynting-Robertson damping of laser beam driven lightsails,"Lightsails using Earth-based lasers for propulsion require passive
stabilization to stay within the beam. This can be achieved through the sail's
scattering properties, creating optical restoring forces and torques. Undamped
restoring forces produce uncontrolled oscillations, which could jeopardize the
mission, but it is not obvious how to achieve damping in the vacuum of space.
Using a simple two-dimensional model we show that the Doppler effect and
relativistic aberration of the propelling laser beam create damping terms in
the optical forces and torques. The effect is similar to the Poynting-Robertson
effect causing loss of orbital momentum of dust particles around stars, but can
be enhanced by design of the sail's geometry.",2401.16924v1
2024-02-29,The Equation of Motion for Taut-Line Buzzers,"Equations of motion are developed for the oscillatory rotation of a disk
suspended between twisted strings kept under tension by a hanging mass, to
which additional forces may be applied. In the absence of forcing, damped
harmonic oscillations are observed to decay with an exponential time envelope
for two different string types. This is consistent with damping caused by
string viscosity, rather than air turbulence, and may be quantified in terms of
a quality factor. To test the proposed equation of motion and model for viscous
damping within the string, we measure both the natural oscillation frequency
and the quality factor for widely varied values of string length, string
radius, disk moment of inertia, and hanging mass. The data are found to scale
in good accord with predictions. A variation where rotational kinetic energy is
converted back and forth to spring potential energy is also discussed.",2402.19285v1
2024-03-08,A design methodology for nonlinear oscillator chains enabling energy localization tuning and soliton stability enhancement with optimal damping,"In this paper, the vibration energy localization in coupled nonlinear
oscillators is investigated, based on the creation of standing solitons. The
main objective is to establish a design methodology for mechanical lattices
using the Nonlinear Schr\""odinger Equation (NLSE) as a guide strategy, even in
the presence of damping. A three-dimensional diagram is used to illustrate
stable parameter regions for damped stationary solitons. Moreover, an analysis
of the influence of the number of oscillators in the system, and a numerical
investigation regarding the stability of solitonic behavior is done. Through
numerical analyses, it is observed that the developed algorithm not only has
the capability to locate the highest amplitudes in the chain of oscillators,
but also to control the intensity at which these amplitudes are located
according to design requirements. The outcomes of the proposed methodology
elucidate the impact that the coupling stiffness has on the stabilization of
the NLSE, as well as the influence of the number of oscillators on the
continuity hypothesis. The developed algorithm holds potential for practical
applications in mechanical engineering since the NLSE is used as a design line
rather than as a consequence of the phenomenon description.",2403.05176v1
2024-03-08,Damping Obliquities of Hot Jupiter Hosts by Resonance Locking,"When orbiting hotter stars, hot Jupiters are often highly inclined relative
to their host star equator planes. By contrast, hot Jupiters orbiting cooler
stars are more aligned. Prior attempts to explain this correlation between
stellar obliquity and effective temperature have proven problematic. We show
how resonance locking -- the coupling of the planet's orbit to a stellar
gravity mode (g mode) -- can solve this mystery. Cooler stars with their
radiative cores are more likely to be found with g-mode frequencies increased
substantially by core hydrogen burning. Strong frequency evolution in resonance
lock drives strong tidal evolution; locking to an axisymmetric g mode damps
semi-major axes, eccentricities, and as we show for the first time,
obliquities. Around cooler stars, hot Jupiters evolve into spin-orbit alignment
and avoid engulfment. Hotter stars lack radiative cores, and therefore preserve
congenital spin-orbit misalignments. We focus on resonance locks with
axisymmetric modes, supplementing our technical results with simple physical
interpretations, and show that non-axisymmetric modes also damp obliquity.",2403.05616v1
2024-03-10,Linear-in-temperature resistivity and Planckian dissipation arise in a stochastic quantization model of Cooper pairs,"We suppose that a Cooper pair (CP) will experience a damping force exerted by
the condensed matter. A Langevin equation of a CP in two dimensional condensed
matter is established. Following a method similar to Nelson's stochastic
mechanics, generalized Schr\""{o}dinger equation of a CP in condensed matter is
derived. If the CPs move with a constant velocity, then the corresponding
direct current (DC) electrical conductivity can be calculated. Therefore, a
Drude like formula of resistivity of CPs is derived. We suppose that the
damping coefficient of CPs in two dimensional cuprate superconductors is a
linear function of temperature. Then the resistivity and scattering rate of CPs
turn out to be also linear-in-temperature. The origin of linear-in-temperature
resistivity and Planckian dissipation in cuprate superconductors may be the
linear temperature dependence of the damping coefficient of CPs.",2403.09710v1
2002-09-12,Kinematical solution of the UHE-cosmic-ray puzzle without a preferred class of inertial observers,"Among the possible explanations for the puzzling observations of cosmic rays
above the GZK cutoff there is growing interest in the ones that represent
kinematical solutions, based either on general formulations of particle physics
with small violations of Lorentz symmetry or on a quantum-gravity-motivated
scheme for the breakup of Lorentz symmetry. An unappealing aspect of these
cosmic-ray-puzzle solutions is that they require the existence of a preferred
class of inertial observers. Here I propose a new kinematical solution of the
cosmic-ray puzzle, which does not require the existence of a preferred class of
inertial observers. My proposal is a new example of a type of relativistic
theories, the so-called ""doubly-special-relativity"" theories, which have
already been studied extensively over the last two years. The core ingredient
of the proposal is a deformation of Lorentz transformations in which also the
Planck scale $E_p$ (in addition to the speed-of-light scale $c$) is described
as an invariant. Just like the introduction of the invariant $c$ requires a
deformation of the Galileian transformations into the Lorentz transformations,
the introduction of the invariant $E_p$ requires a deformation of the Lorentz
transformations, but there is no special class of inertial observers. The
Pierre Auger Observatory and the GLAST space telescope should play a key role
in future developments of these investigations. I also emphasize that the
doubly-special-relativity theory here proposed, besides being the first one to
provide a solution for the cosmic-ray puzzle, is also the first one in which a
natural description of macroscopic bodies is achieved, and may find
applications in the context of a recently-proposed dark-energy scenario.",0209232v1
2005-10-14,Nonlinear stability of relativistic sheared planar jets,"The linear and non-linear stability of sheared, relativistic planar jets is
studied by means of linear stability analysis and numerical hydrodynamical
simulations. Our results extend the previous Kelvin-Hemlholtz stability studies
for relativistic, planar jets in the vortex sheet approximation performed by
Perucho et al. (2004a,b) by including a shear layer between the jet and the
external medium and more general perturbations. The models considered span a
wide range of Lorentz factors ($2.5-20$) and internal energies ($0.08 c^2-60
c^2$) and are classified into three classes according to the main
characteristics of their long-term, non-linear evolution. We observe a clear
separation of these three groups in a relativistic Mach-number Lorentz-factor
plane. Jets with a low Lorentz factor and small relativistic Mach number are
disrupted after saturation. Those with a large Lorentz factor and large
relativistic Mach number are the stablest, due to the appearance of short
wavelength resonant modes which generate local mixing and heating in the shear
layer around a fast, unmixed core, giving a plausible solution for the problem
of the long-term stability of relativistic jets. A third group is present
between them, including jets with intermediate values of Lorentz factor and
relativistic Mach number, which are disrupted by a slow process of mixing
favored by an efficient and continuous conversion of kinetic into internal
energy. In the long term, all the models develop a distinct transversal
structure (shear/transition layers) as a consequence of KH perturbation growth,
depending on the class they belong to. The properties of these shear layers are
analyzed in connection with the parameters of the original jet models.",0510426v1
2003-09-09,The three perspectives on the quantum-gravity problem and their implications for the fate of Lorentz symmetry,"Each approach to the quantum-gravity problem originates from expertise in one
or another area of theoretical physics. The particle-physics perspective
encourages one to attempt to reproduce in quantum gravity as much as possible
of the successes of the Standard Model of particle physics, and therefore, as
done in String Theory, the core features of quantum gravity are described in
terms of graviton-like exchange in a background classical spacetime. From the
general-relativity perspective it is natural to renounce to any reference to a
background spacetime, and to describe spacetime in a way that takes into
account the in-principle limitations of measurements. The Loop Quantum Gravity
approach and the approaches based on noncommutative geometry originate from
this general-relativity perspective. The condensed-matter perspective, which
has been adopted in a few recent quantum-gravity proposals, naturally leads to
scenarios in which some familiar properties of spacetime are only emergent,
just like, for example, some emergent collective degrees of freedom are
relevant to the description of certain physical systems only near a critical
point. Both from the general-relativity perspective and from the
condensed-matter perspective it is natural to explore the possibility that
quantum gravity might have significant implications for the fate of Lorentz
symmetry in the Planckian regime. From the particle-physics perspective there
is instead no obvious reason to renounce to exact Lorentz symmetry, although
(``spontaneous'') Lorentz symmetry breaking is of course possible. A
fast-growing phenomenological programme looking for Planck-scale departures
from Lorentz symmetry can contribute to this ongoing debate.",0309054v1
2008-03-27,Simulations of Ultrarelativistic Magnetodynamic Jets from Gamma-ray Burst Engines,"Long-duration gamma-ray bursts (GRBs) require an engine capable of driving a
jet of plasma to ultrarelativistic bulk Lorentz factors of up to several
hundred and into narrow opening angles of a few degrees. We use global
axisymmetric stationary solutions of magnetically-dominated (force-free)
ultrarelativistic jets to test whether the popular magnetic-driving paradigm
can generate the required Lorentz factors and opening angles. Our global
solutions are obtained via time-dependent relativistic ideal magnetodynamical
numerical simulations which follow the jet from the central engine to beyond
six orders of magnitude in radius. Our model is primarily motivated by the
collapsar model, in which a jet is produced by a spinning black hole or neutron
star and then propagates through a massive stellar envelope. We find that the
size of the presupernova progenitor star and the radial profile of pressure
inside the star determine the terminal Lorentz factor and opening angle of the
jet. At the radius where the jet breaks out of the star, our well-motivated
fiducial model generates a Lorentz factor $\gamma\sim 400$ and a half-opening
angle $\theta_j\sim 2^\circ$, consistent with observations of many
long-duration GRBs. Other models with slightly different parameters give
$\gamma$ in the range 100 to 5000 and $\theta_j$ from $0.1^\circ$ to
$10^\circ$, thus reproducing the range of properties inferred for GRB jets. A
potentially observable feature of some of our solutions is that the maximum
Poynting flux in the jet is found at $\theta \sim \theta_j$ with the jet power
concentrated in a hollow cone, while the maximum in the Lorentz factor occurs
at an angle $\theta$ substantially smaller than $\theta_j$ also in a hollow
cone. [abridged]",0803.3807v2
2010-08-22,Graviton as a Goldstone boson: Nonlinear Sigma Model for Tensor Field Gravity,"Spontaneous Lorentz invariance violation (SLIV) realized through a nonlinear
tensor field constraint H_{}^2=\pm M^2 (M is the proposed scale for Lorentz
violation) is considered in tensor field gravity theory, which mimics
linearized general relativity in Minkowski space-time. We show that such a SLIV
pattern, due to which the true vacuum in the theory is chosen, induces massless
tensor Goldstone modes some of which can naturally be associated with the
physical graviton. When expressed in terms of the pure Goldstone modes, this
theory looks essentially nonlinear and contains a variety of Lorentz and CPT
violating couplings. Nonetheless, all SLIV effects turn out to be strictly
cancelled in all the lowest order processes considered, provided that the
tensor field gravity theory is properly extended to general relativity (GR).
So, as we generally argue, the measurable effects of SLIV, induced by
elementary vector or tensor fields, are related to the accompanying gauge
symmetry breaking rather than to spontaneous Lorentz violation. The latter
appears by itself to be physically unobservable, only resulting in a
non-covariant gauge choice in an otherwise gauge invariant and Lorentz
invariant theory. However, while Goldstonic vector and tensor field theories
with exact local invariance are physically indistinguishable from conventional
gauge theories, there might appear some principal distinctions if this local
symmetry were slightly broken at very small distances controlled by quantum
gravity in an explicit, rather than spontaneous, way that could eventually
allow one to differentiate between them observationally.",1008.3707v4
2012-09-21,What governs the bulk velocity of the jet components in active galactic nuclei?,"We use a sample of radio-loud active galactic nuclei (AGNs) with measured
black hole masses to explore the jet formation mechanisms in these sources.
Based on the K\""{o}nigl's inhomogeneous jet model, the jet parameters, such as
the bulk motion Lorentz factor, magnetic field strength, and electron density
in the jet, can be estimated with the very long-baseline interferometry and
X-ray data. We find a significant correlation between black hole mass and the
bulk Lorentz factor of the jet components for this sample, while no significant
correlation is present between the bulk Lorentz factor and the Eddington ratio.
The massive black holes will be spun up through accretion, as the black holes
acquire mass and angular momentum simultaneously through accretion. Recent
investigation indeed suggested that most supermassive black holes in elliptical
galaxies have on average higher spins than the black holes in spiral galaxies,
where random, small accretion episodes (e.g., tidally disrupted stars,
accretion of molecular clouds) might have played a more important role. If this
is true, the correlation between black hole mass and the bulk Lorentz factor of
the jet components found in this work implies that the motion velocity of the
jet components is probably governed by the black hole spin. No correlation is
found between the magnetic field strength at $10R_{\rm S}$ ($R_{\rm S}=2GM/c^2$
is the Schwarzschild radius) in the jets and the bulk Lorentz factor of the jet
components for this sample. This is consistent with the black hole spin
scenario, i.e., the faster moving jets are magnetically accelerated by the
magnetic fields threading the horizon of more rapidly rotating black holes. The
results imply that the Blandford-Znajek (BZ) mechanism may dominate over the
Blandford-Payne (BP) mechanism for the jet acceleration at least in these
radio-loud AGNs.",1209.4702v1
2016-10-06,Eugene Paul Wigner's Nobel Prize,"In 1963, Eugene Paul Wigner was awarded the Nobel Prize in Physics for his
contributions to the theory of the atomic nucleus and the elementary particles,
particularly through the discovery and application of fundamental symmetry
principles. There are no disputes about this statement. On the other hand,
there still is a question of why the statement did not mention Wigner's 1939
paper on the Lorentz group, which was regarded by Wigner and many others as his
most important contribution in physics. By many physicists, this paper was
regarded as a mathematical exposition having nothing to do with physics.
However, it has been more than one half century since 1963, and it is of
interest to see what progress has been made toward understanding physical
implications of this paper and its historical role in physics. Wigner in his
1963 paper defined the subgroups of the Lorentz group whose transformations do
not change the four-momentum of a given particle, and he called them the little
groups. Thus, Wigner's little groups are for internal space-time symmetries of
particles in the Lorentz-covariant world. Indeed, this subgroup can explain the
electron spin and spins of other massive particles. However, for massless
particles, there was a gap between his little group and electromagnetic waves
derivable Maxwell's equations. This gap was not completely removed until 1990.
The purpose of this report is to review the stormy historical process in which
this gap is cleared. It is concluded that Wigner's little groups indeed can be
combined into one Lorentz-covariant formula which can dictate the symmetry of
the internal space-time time symmetries of massive and massless particles in
the Lorentz covariant world, just like Einstein's energy-momentum relation
applicable to both slow and massless particles.",1610.01740v1
2017-02-10,Vacuum Cherenkov radiation for Lorentz-violating fermions,"The current work focuses on the process of vacuum Cherenkov radiation for
Lorentz-violating fermions that are described by the minimal Standard-Model
Extension (SME). To date, most considerations of this important hypothetical
process have been restricted to Lorentz-violating photons, as the necessary
theoretical tools for the SME fermion sector have not been available. With
their development in a very recent paper, we are now in a position to compute
the decay rates based on a modified Dirac theory. Two realizations of the
Cherenkov process are studied. In the first scenario, the spin projection of
the incoming fermion is assumed to be conserved, and in the second, the spin
projection is allowed to flip. The first type of process is shown to be still
forbidden for the dimensionful $a$ and $b$ coefficients where there are strong
indications that it is energetically disallowed for the $H$ coefficients, as
well. However, it is rendered possible for the dimensionless $c$, $d$, $e$,
$f$, and $g$ coefficients. For large initial fermion energies, the decay rates
for the $c$ and $d$ coefficients were found to grow linearly with momentum and
to be linearly suppressed by the smallness of the Lorentz-violating coefficient
where for the $e$, $f$, and $g$ coefficients this suppression is even
quadratic. The decay rates vanish in the vicinity of the threshold, as
expected. The decay including a fermion spin flip plays a role for the
spin-nondegenerate operators and it was found to occur for the dimensionful $b$
and $H$ coefficients as well as for the dimensionless $d$ and $g$. The
characteristics of this process differ much from the properties of the
spin-conserving one, e.g., there is no threshold. Based on experimental data of
ultra-high-energy cosmic rays, new constraints on Lorentz violation in the
quark sector are obtained from the thresholds.",1702.03171v3
2020-06-30,The Boostless Bootstrap: Amplitudes without Lorentz boosts,"Poincar\'e invariance is a well-tested symmetry of nature and sits at the
core of our description of relativistic particles and gravity. At the same
time, in most systems Poincar\'e invariance is not a symmetry of the ground
state and is hence broken spontaneously. This phenomenon is ubiquitous in
cosmology where Lorentz boosts are spontaneously broken by the existence of a
preferred reference frame in which the universe is homogeneous and isotropic.
This motivates us to study scattering amplitudes without requiring invariance
of the interactions under Lorentz boosts. In particular, using on-shell methods
and assuming massless, relativistic and luminal particles of any spin, we show
that the allowed interactions around Minkowski spacetime are severely
constrained by unitarity and locality in the form of consistent factorization.
The existence of an interacting massless spin-2 particle enforces (analytically
continued) three-particle amplitudes to be Lorentz invariant, even those that
do not involve a graviton, such as cubic scalar couplings. We conjecture this
to be true for all n-particle amplitudes. Also, particles of spin S > 2 cannot
self-interact nor can be minimally coupled to gravity, while particles of spin
S > 1 cannot have electric charge. Given the growing evidence that free
gravitons are well described by massless, luminal relativistic particles, our
results imply that cubic graviton interactions in Minkowski must be those of
general relativity up to a unique Lorentz-invariant higher-derivative
correction of mass dimension 9. Finally, we point out that consistent
factorization for massless particles is highly IR sensitive and therefore our
powerful at-space results do not straightforwardly apply to curved spacetime.",2007.00027v3
2013-09-29,Simulating gamma-ray binaries with a relativistic extension of RAMSES,"Gamma-ray binaries are composed of a massive star and a rotation-powered
pulsar with a highly relativistic wind. The collision between the winds from
both objects creates a shock structure where particles are accelerated,
resulting in the observed high energy emission. We study the impact of special
relativity on the structure and stability of the colliding wind region and
highlight the differences with colliding winds from massive stars. We focus on
evolution with increasing values of the Lorentz factor of the pulsar wind,
keeping in mind that current simulations are unable to reach the expected
values of the pulsar wind Lorentz factors by orders of magnitude. We use high
resolution numerical simulations with a relativistic extension to the
hydrodynamics code RAMSES we have developed. Using 2D simulations, we focus on
the region close to the binary, neglecting orbital motion. We use different
values of the Lorentz factor of the pulsar wind, up to 16. We find analytic
scaling relations between stellar wind collisions and gamma-ray binaries. They
provide the position of the contact discontinuity. The position of the shocks
strongly depends on the Lorentz factor, the relativistic wind is more
collimated than expected based on non-relativistic simulations. Beyond a
certain distance, the shocked flow is accelerated to its initial velocity and
follows adiabatic expansion. We provide guidance for extrapolation towards more
realistic values of the Lorentz factor of the pulsar wind. We extended the
adaptive mesh refinement code RAMSES to relativistic hydrodynamics. This code
is suited for the study of astrophysical objects such as pulsar wind nebulae,
gamma-ray bursts or relativistic jets and will be part of the next public
release of RAMSES. Using this code we performed simulations of gamma-ray
binaries, highlighting the limits and possibilities of current hydrodynamic
models of such systems.",1309.7629v1
2016-08-05,Constraining the Rate of Primordial Black-Hole Explosions and Extra Dimension Scale using a Low-Frequency Radio Antenna Array,"An exploding primordial black-hole (PBH) may produce a single pulse of
electromagnetic radiation detectable at the low-frequency end of the radio
spectrum. Furthermore, a radio transient from an exploding PBH could be a
signature of an extra spatial dimension. We describe here an approach for
searching for PBH explosions using a low-frequency radio antenna array, and as
a practical example, the results of a such a search using the
Eight-meter-wavelength Transient Array (ETA). No compelling astrophysical
signal was detected in $\approx 4$ hours of data implying an observational
upper limit on the rate of exploding PBHs is $4.2 \times 10^{-7}
\,\rm{pc}^{-3}\,\rm{yr}^{-1}$ for an exploding PBH with a fireball Lorentz
factor of $10^{4.5}$ for the standard scenario of Page and Hawking. This rate
limit is the strongest constraint yet set for PBH explosions with this fireball
Lorentz factor. Observations ($\sim300$ hours) using the Arecibo Observatory
were used to set a stronger constraint on the rate of PBH explosions for a
fireball Lorentz factor of $10^{4.6}$ but the limit set by those observations
for the fireball Lorentz factor considered here are less stringent by more than
an order of magnitude. The limits considered here are applicable to exploding
PBHs in the halo of the Galaxy. These observations also imply an upper limit of
$2.0 \times 10^{-4} \,\rm{pc}^{-3}\,\rm{yr}^{-1}$ on the rate of PBH explosions
in the context of certain extra dimension models as described by Kavic et al.
This rate limit is for a fireball Lorentz factor of $10^{4.3}$ which
corresponds to an extra dimension compactification scale of $3.0 \times
10^{-18}$m.",1608.01945v3
2016-08-17,The History of GRB Outflows: Ejection Lorentz Factor and Radiation Location of X-Ray Flares,"We present time-resolved spectral analysis of the steep decay segments of 29
bright X-ray flares of gamma-ray bursts (GRBs) observed with the Swift/X-ray
telescope, and model their lightcurves and spectral index evolution behaviors
with the curvature effect model. Our results show that the observed rapid flux
decay and strong spectral index evolution with time can be well fit with this
model, and the derived characteristic timescales ($t_c$) are in the range of
$33\sim 264$ seconds. Using an empirical relation between the peak luminosity
and the Lorentz factor derived from the prompt gamma-rays, we estimate the
Lorentz factors of the flares ($\Gamma_{\rm X}$). We obtain $\Gamma_{\rm
X}=17\sim 87$ with a median value of $52$, which is smaller than the initial
Lorentz factors of prompt gamma-ray fireballs. With the derived $t_c$ and
$\Gamma_{\rm X}$, we constrain the radiating regions of 13 X-ray flares,
yielding $R_{\rm X}=(0.2\sim 1.1)\times 10^{16}$ cm, which are smaller than the
radii of the afterglow fireballs at the peak times of the flares. A long
evolution feature from prompt gamma-ray phase to the X-ray epoch is found by
incorporating our results with a sample of GRBs whose initial Lorentz factors
are available in literatures, i.e., $\Gamma\propto [t_{p}/(1+z)]^{-0.69\pm
0.06}$. These results may shed lights on the long term evolution of GRB central
engines.",1608.05028v2
2019-10-11,Kinetic Theory for the Low-Density Lorentz Gas,"The Lorentz gas is one of the simplest and most widely-studied models for
particle transport in matter. It describes a cloud of non-interacting gas
particles in an infinitely extended array of identical spherical scatterers.
The model was introduced by Lorentz in 1905 who, following the pioneering ideas
of Maxwell and Boltzmann, postulated that in the limit of low scatterer
density, the macroscopic transport properties of the model should be governed
by a linear Boltzmann equation. The linear Boltzmann equation has since proved
a useful tool in the description of various phenomena, including semiconductor
physics and radiative transfer. A rigorous derivation of the linear Boltzmann
equation from the underlying particle dynamics was given, for random scatterer
configurations, in three seminal papers by Gallavotti, Spohn and
Boldrighini-Bunimovich-Sinai. The objective of the present study is to develop
an approach for a large class of deterministic scatterer configurations,
including various types of quasicrystals. We prove the convergence of the
particle dynamics to transport processes that are in general (depending on the
scatterer configuration) not described by the linear Boltzmann equation. This
was previously understood only in the case of the periodic Lorentz gas through
work of Caglioti-Golse and Marklof-Str\""ombergsson. Our results extend beyond
the classical Lorentz gas with hard sphere scatterers, and in particular hold
for general classes of spherically symmetric finite-range potentials. We employ
a rescaling technique that randomises the point configuration given by the
scatterers' centers. The limiting transport process is then expressed in terms
of a point process that arises as the limit of the randomised point
configuration under a certain volume-preserving one-parameter linear group
action.",1910.04982v2
2019-11-30,Centrifugal acceleration of protons in the vicinity of a supermassive black hole,"Acceleration of protons in the active galactic nuclei is considered. The
largest energy is achieved by protons during centrifugal acceleration in the
magnetosphere of the central machine. When the proton accelerated in the
magnetosphere of a black hole approaches light cylinder surface, acceleration
occurs mainly in the azimuthal direction, i.e. the acceleration is centrifugal.
In this paper the acceleration of a proton having smaller synchrotron losses
compared to the electron is considered. As a proton experiences the highest
energy increase while accelerating near the light surface, a partial solution
for the maximum Lorentz factor can be obtained there. In the analysis the
obtained dependence of the maximum energy on the parameter of particle
magnetization $ \kappa $ and parameter $ \alpha $ which reflects the relation
of toroidal $ B_\phi $ and poloidal $ B_T $ magnetic fields , has led to the
conclusion that the achievement of theoretical maximum limit of Lorentz factor
value $ \gamma_m=\kappa^{-1}$ is not possible for an accelerated particle in
the magnetosphere of a black hole due to restrictions of the topology of
toroidal and poloidal magnetic fields imposed. The analysis of special cases of
the relation of toroidal and poloidal magnetic field has shown that in the
presence of magnetic field that is significantly more toroidal the maximum
Lorentz factor value reaches $\gamma_m = \kappa^ {-2/3} $, in case when
toroidal field becomes smaller in comparison to poloidal field the maximum
Lorentz factor value does not exceed $\gamma_m = \kappa^ {-1/2} $. For a number
of objects, such as M87 and Sgr. A *, maximum Lorentz factor values for
accelerated protons for scenarios of existence or lack of toroidal magnetic
field have been derived. The obtained results for magnetosphere of Sgr. A * has
confirmed by the experimental data obtained on the massive HESS of Cherenkov
telescopes.",1912.00170v1
2019-12-31,"Higher Anomalies, Higher Symmetries, and Cobordisms II: Lorentz Symmetry Extension and Enriched Bosonic/Fermionic Quantum Gauge Theory","We systematically study Lorentz symmetry extensions in quantum field theories
(QFTs) and their 't Hooft anomalies via cobordism. The total symmetry $G'$ can
be expressed in terms of the extension of Lorentz symmetry $G_L$ by an internal
global symmetry $G$ as $1 \to G \to G' \to G_L \to 1$. By enumerating all
possible $G_L$ and symmetry extensions, other than the familiar
SO/Spin/O/Pin$^{\pm}$ groups, we introduce a new EPin group (in contrast to
DPin), and provide natural physical interpretations to exotic groups E($d$),
EPin($d$), (SU(2)$\times$E(d))/$\mathbb{Z}_2$,
(SU(2)$\times$EPin(d))/$\mathbb{Z}_2^{\pm}$, etc. By Adams spectral sequence,
we systematically classify all possible $d$d Symmetry Protected Topological
states (SPTs as invertible TQFTs) and $(d-1)$d 't Hooft anomalies of QFTs by
co/bordism groups and invariants in $d\leq 5$. We further gauge the internal
$G$, and study Lorentz symmetry-enriched Yang-Mills theory with discrete theta
terms given by gauged SPTs. We not only enlist familiar bosonic Yang-Mills but
also discover new fermionic Yang-Mills theories (when $G_L$ contains a graded
fermion parity $\mathbb{Z}_2^F$), applicable to bosonic (e.g., Quantum Spin
Liquids) or fermionic (e.g., electrons) condensed matter systems. For a pure
gauge theory, there is a one form symmetry $I_{[1]}$ associated with the center
of the gauge group $G$. We further study the anomalies of the emergent symmetry
$I_{[1]}\times G_L$ by higher cobordism invariants as well as QFT analysis. We
focus on the simply connected $G=$SU(2) and briefly comment on non-simply
connected $G=$SO(3), U(1), other simple Lie groups, and Standard Model gauge
groups (SU(3)$\times$SU(2)$\times$U(1))/$\mathbb{Z}_q$. We comment on SPTs
protected by Lorentz symmetry, and the symmetry-extended trivialization for
their boundary states.",1912.13504v2
2020-11-11,On the Geometric Orbit Property for Lorentz Manifolds,"The geodesic orbit property has been studied intensively for Riemannian
manifolds. Geodesic orbit spaces are homogeneous and allow simplifications of
many structural questions using the Lie algebra of the isometry group. Weakly
symmetric Riemannian manifolds are geodesic orbit spaces. Here we define
""naturally reductive"" for pseudo-Riemannian manifolds and note that they are
geodesic orbit spaces. A few years ago two of the authors proved that weakly
symmetric pseudo-Riemannian manifolds are geodesic orbit spaces. In particular
these results apply to pseudo-Riemannian Lorentz manifolds. There our main
results are Theorems 4.2 and 5.1. In the Riemannian case the nilpotent isometry
group for a geodesic orbit nilmanifold is abelian or $2$-step nilpotent.
Examples show that this fails dramatically in the pseudo-Riemannian case. Here
we concentrate on the geodesic orbit property for Lorentz nilmanifolds $G/H$
with $G = N \rtimes H$ and $N$ nilpotent. When the metric is nondegenerate on
$[\mathfrak{n},\mathfrak{n}]$, Theorem 4.2 shows that $N$ either is at most
$2$-step nilpotent as in the Riemannian situation, or is $4$-step nilpotent,
but cannot be $3$-step nilpotent. Examples show that these bounds are the best
possible. Surprisingly, Theorem 5.1 shows that $N$ is at most $2$-step
nilpotent when the metric is degenerate on $[\mathfrak{n},\mathfrak{n}]$. Both
theorems give additional structural information and specialize to naturally
reductive and to weakly symmetric Lorentz nilmanifolds.
  Key Words: Geodesic Orbit Space; Lorentz nilmanifold; Weakly Symmetric Space;
Naturally Reductive Space; Pseudo-Riemannian Manifold.",2011.06054v3
1996-05-06,A Keck HIRES Investigation of the Metal Abundances and Kinematics of Three Damped Lya Systems Toward Q2206-199,"We present high resolution, high SNR spectra of the QSO Q2206-199 obtained
with HIRES on the 10m W.M. Keck Telescope. Our analysis focuses on the two
previously identified damped \lya systems found at $z=1.920$ and $z=2.076$. For
each system, we measure accurate abundances. The $z=1.920$ system exhibits the
highest metallicity we have measured for a damped \lya system. We report the
first confident ($>5 \sigma$) detection of Ti in a QSO absorption line system.
By contrast the $z=2.076$ system is the most metal poor we have analyzed,
showing absorption features for only the strongest transitions. We find no
positive evidence for the presence of dust in either system. The two damped
systems exhibit significantly different kinematic characteristics, yet we
contend the two systems are consistent with one physical description: that of a
thick, rotating disk.
  We investigate a very strong Mg II system at $z=0.752$ which is very likely
yet a third damped \lya system. The very weak Mn II and Ti II transitions have
been positively measured and imply $\log \N{HI} > 19.0$. We analyze the
abundance ratios [Mn/Fe] and [Ti/Fe] and their values are inconsistent with
dust depletion, yet consistent with the abundance pattern detected for halo
stars in the Galaxy (see Lu et al. 1996a).
  Finally, we identify a C IV system at $z=2.014$ that shows a very narrow
feature in Si IV and C IV absorption. The corresponding $b$ values (5.5 \kms
and 8.9 \kms for Si IV and C IV) for this component suggest a temperature of
$4.7 \sci{4} \rm K$. Because collisional ionization can explain the observed
abundances only for $T > 8 \sci{4} \rm K$, we contend these ions must have
formed through a different physical process (e.g. photoionization).",9605021v2
1996-09-09,The Population of Damped Lyman-alpha and Lyman Limit Systems in the Cold Dark Matter Model,"Lyman limit and damped Lyman-alpha absorption systems probe the distribution
of collapsed, cold gas at high redshift. Numerical simulations that incorporate
gravity and gas dynamics can predict the abundance of such absorbers in
cosmological models. We develop a semi-analytical method to correct the
numerical predictions for the contribution of unresolved low mass halos, and we
apply this method to the Katz et al. (1996) simulation of the standard cold
dark matter model ($\Omega=1$, $h=0.5$, $\Omega_b=0.05$, $\sigma_8=0.7$). Using
this simulation and higher resolution simulations of individual low mass
systems, we determine the relation between a halo's circular velocity $v_c$ and
its cross section for producing Lyman limit or damped absorption. We combine
this relation with the Press-Schechter formula for the abundance of halos to
compute the number of absorbers per unit redshift. The resolution correction
increases the predicted abundances by about a factor of two at z=2, 3, and 4,
bringing the predicted number of damped absorbers into quite good agreement
with observations. Roughly half of the systems reside in halos with circular
velocities $v_c>100\kms$ and half in halos with $35\kms<v_c<100\kms$. Halos
with $v_c>150\kms$ typically harbor two or more systems capable of producing
damped absorption. Even with the resolution correction, the predicted abundance
of Lyman limit systems is a factor of three below observational estimates,
signifying either a failure of standard CDM or a failure of these simulations
to resolve the systems responsible for most Lyman limit absorption. By
comparing simulations with and without star formation, we find that depletion
of the gas supply by star formation affects absorption line statistics at
$z>=2$ only for column densities exceeding $N_{HI}=10^{22} cm^{-2}$.",9609072v1
1998-05-22,Protogalactic Disk Models of Damped Lya Kinematics,"We present new observational results on the kinematics of the damped lya
systems. Our full sample is now comprised of 31 low-ion profiles and exhibits
similar characteristics to the sample from Paper I. The primary exception is
that the new distribution of velocity widths includes values out to a maximum
of nearly 300 km/s, approx 100 km/s greater than the previous maximum. These
high velocity width systems will significantly leverage models introduced to
explain the damped lya systems. Comparing the characteristics from low-redshift
and high-redshift sub-samples, we find no evidence for significant evolution in
the kinematic properties of protogalaxies from z = 2.0 - 3.3.
  The new observations give greater statistical significance to the main
conclusions of our first paper. In particular, those models inconsistent with
the damped lya observations in Paper I are ruled out at even higher levels of
confidence. At the same time, the observations are consistent with a population
of rapidly rotating, thick disks (the TRD model) at high redshift.
  Buoyed by the success of the TRD model, we investigate it more closely by
considering more realistic disk properties. Our goal is to demonstrate the
statistical power of the damped lya observations by investigating the
robustness of the TRD model. In particular, we study the effects of warping,
realistic rotation curves, and photoionization on the kinematics of disks in
the TRD model. The principal results are: (1) disk warping has only minimal
effect on the kinematic results, primarily influencing the effective disk
thickness, (2) the TRD model is robust to more realistic rotation curves; (3)
the effects of photoionization require thicker disks to give consistent
velocity width distributions. [abridged]",9805293v1
2000-05-05,UVES observations of QSO 0000-2620: oxygen and zinc abundances in the Damped Ly-alpha galaxy at z_abs=3.3901,"Observations of the QSO 0000-2620 with UVES spectrograph at the 8.2m ESO
KUEYEN telescope are used for abundance analysis of the damped Ly-alpha system
at z_{abs}=3.3901. Several Oxygen lines are identified in the Ly_alpha forest
and a measure for the oxygen abundance is obtained at [O/H]=-1.85 +/- 0.1 by
means of the unsaturated OI 925 A and OI 950 A lines. This represents the most
accurate O measurement in a damped Ly_alpha galaxy so far. We have also
detected ZnII 2026 A and CrII 2056, 2062 A redshifted at about 8900 A and found
abundances [Zn/H] = -2.07 +/- 0.1 and [Cr/H]=-1.99 +/- 0.1. Furthermore,
previous measurements of Fe, Si, Ni and N have been refined yielding
[Fe/H]=-2.04 +/- 0.1, [Si/H]=-1.90 +/- 0.1, [Ni/H]=-2.27 +/- 0.1, and
[N/H]=-2.68 +/- 0.1. The abundance of the non-refractory element zinc is the
lowest among the damped Ly-alpha systems showing that the associated
intervening galaxy is indeed in the early stages of its chemical evolution. The
fact that the Zn abundance is identical to that of the refractory elements Fe
and Cr suggests that dust grains have not formed yet. In this Damped Ly-alpha
system the observed [O,S,Si/Zn,Fe,Cr] ratios, in whatever combination are
taken, are close to solar (i.e 0.1-0.2 dex) and do not show the
[alpha-element/Fe] enhancement observed in Milky Way stars of comparable
metallicity. The observed behavior supports a galaxy evolution model
characterized by either episodic or low star formation rate rather than a
Milky-Way-type evolutionary model.",0005098v1
2002-02-06,The UCSD HIRES/KeckI Damped Lya Abundance Database III. An Empirical Study of Photoionization in the Damped Lya System Toward GB1759+7539,"We investigate the ionization state of the damped Lya system at z=2.62 toward
GB1759+7539 through an analysis of ionic ratios sensitive to photoionization:
ArI/SII, FeIII/FeII, NII/NI, AlIII/AlII. Approximately half of the metals arise
in a mostly neutral velocity component with HI/H > 0.9, based on FeIII/FeII <
0.013. In contrast, the remaining half exhibits FeIII/FeII~0.3 indicative of a
partially ionized medium with HI/H~0.5. These conclusions are supported by the
observed NII/NI, AlIII/AlII, and ArI/SII ratios.
  We assess ionization corrections for the observed column densities through
photoionization models derived from the CLOUDY software package. In the neutral
gas, the ionization corrections are negligible except for ArI. However for the
partially ionized gas, element abundance ratios differ from the ionic ratios by
0.1-0.3 dex for (SiII, SII, NiII, AlII)/FeII ratios and more for (NI,
ArI)/FeII. Independent of the shape of the photoionizing spectrum and
assumptions on the number of ionization phases, these ionization corrections
have minimal impact (<0.1dex) on the total metallicity inferred for this damped
Lya system. Measurements on the relative elemental abundances of the partially
ionized gas, however, have a greater than ~0.15 dex uncertainty which hides the
effects of nucleosynthesis and dust depletion.
  We caution the reader that this damped system is unusual for a number of
reasons (e.g. a very low ArI/SII ratio) and we believe its ionization
properties are special but not unique. Nevertheless, it clearly shows the value
of examining photoionization diagnostics like FeIII/FeII in a larger sample of
systems.",0202140v1
2009-09-26,Damped and sub-damped Lyman-? absorbers in z > 4 QSOs,"We present the results of a survey for damped (DLA, log N(H I) > 20.3) and
sub-damped Lyman-? systems (19.5 < log N(H I) < 20.3) at z > 2.55 along the
lines-of-sight to 77 quasars with emission redshifts in the range 4 < zem <
6.3. Intermediate resolution (R ? 4300) spectra have been obtained with the
Echellette Spectrograph and Imager (ESI) mounted on the Keck telescope. A total
of 100 systems with log N(H I) > 19.5 are detected of which 40 systems are
damped Lyman-? systems for an absorption length of ?X = 378. About half of the
lines of sight of this homogeneous survey have never been investigated for
DLAs. We study the evolution with redshift of the cosmological density of the
neutral gas and find, consis- tently with previous studies at similar
resolution, that ?DLA,H I decreases at z > 3.5. The overall cosmological
evolution of ?HI shows a peak around this redshift. The H I column density
distribution for log N(H I) ? 20.3 is ?tted, consistently with previous
surveys, with a single power-law of index ? ? -1.8$\pm$0.25. This power-law
overpredicts data at the high-end and a second, much steeper, power-law (or a
gamma function) is needed. There is a flattening of the function at lower H I
column densities with an index of ? ? ?1.4 for the column density range log N(H
I) = 19.5?21. The fraction of H I mass in sub-DLAs is of the order of 30%. The
H column density distribution does not evolve strongly from z ? 2.5 to z ? 4.5.",0909.4839v2
2009-10-28,Nonlinear envelope equation and nonlinear Landau damping rate for a driven electron plasma wave,"In this paper, we provide a theoretical description, and calculate, the
nonlinear frequency shift, group velocity and collionless damping rate, $\nu$,
of a driven electron plasma wave (EPW). All these quantities, whose physical
content will be discussed, are identified as terms of an envelope equation
allowing one to predict how efficiently an EPW may be externally driven. This
envelope equation is derived directly from Gauss law and from the investigation
of the nonlinear electron motion, provided that the time and space rates of
variation of the EPW amplitude, $E_p$, are small compared to the plasma
frequency or the inverse of the Debye length. $\nu$ arises within the EPW
envelope equation as more complicated an operator than a plain damping rate,
and may only be viewed as such because $(\nu E_p)/E_p$ remains nearly constant
before abruptly dropping to zero. We provide a practical analytic formula for
$\nu$ and show, without resorting to complex contour deformation, that in the
limit $E_p \to 0$, $\nu$ is nothing but the Landau damping rate. We then term
$\nu$ the ""nonlinear Landau damping rate"" of the driven plasma wave. As for the
nonlinear frequency shift of the EPW, it is also derived theoretically and
found to assume values significantly different from previously published ones,
assuming that the wave is freely propagating. Moreover, we find no limitation
in $k \lambda_D$, $k$ being the plasma wavenumber and $\lambda_D$ the Debye
length, for a solution to the dispertion relation to exist, and want to stress
here the importance of specifying how an EPW is generated to discuss its
properties. Our theoretical predictions are in excellent agreement with results
inferred from Vlasov simulations of stimulated Raman scattering (SRS), and an
application of our theory to the study of SRS is presented.",0910.5289v1
2011-05-19,"Tidal dissipation compared to seismic dissipation: in small bodies, in earths, and in superearths","While the seismic quality factor and phase lag are defined solely by the bulk
properties of the mantle, their tidal counterparts are determined both by the
bulk properties and self-gravitation of a body as a whole. For a qualitative
estimate, we model the body with a homogeneous sphere and express the tidal
phase lag through the lag in a sample of material. Although simplistic, our
model is sufficient to understand that the lags are not identical. The
difference emerges because self-gravitation pulls the tidal bulge down. At low
frequencies, this reduces strain and makes tidal damping less efficient in
larger bodies. At high frequencies, competition between self-gravitation and
rheology becomes more complex, though for sufficiently large superearths the
same rule works: the larger the body, the weaker tidal damping in it. Being
negligible for small terrestrial planets and moons, the difference between the
seismic and tidal lagging (and likewise between the seismic and tidal damping)
becomes very considerable for superearths. In those, it is much lower than what
one might expect from using a seismic quality factor. The tidal damping rate
deviates from the seismic damping rate especially in the zero-frequency limit,
and this difference takes place for bodies of any size. So the equal in
magnitude but opposite in sign tidal torques, exerted on one another by the
primary and the secondary, go smoothly through zero as the secondary crosses
the synchronous orbit. We describe the mantle rheology with the Andrade model,
allowing it to lean towards the Maxwell model at the lowest frequencies. To
implement this additional flexibility, we reformulate the Andrade model by
endowing it with a free parameter which is the ratio of the anelastic timescale
to the viscoelastic Maxwell time of the mantle. Some uncertainty in this
parameter's frequency-dependence does not influence our principal conclusions.",1105.3936v12
2014-10-07,The Effect of Nonlinear Landau Damping on Ultrarelativistic Beam Plasma Instabilities,"Very-high energy gamma-rays from extragalactic sources pair-produce off of
the extragalactic background light, yielding an electron-positron pair beam.
This pair beam is unstable to various plasma instabilities, especially the
""oblique"" instability, which can be the dominant cooling mechanism for the
beam. However, recently, it has been claimed that nonlinear Landau damping
renders it physically irrelevant by reducing the effective damping rate to a
low level. Here, we show with numerical calculations that the effective damping
rate is $8\times 10^{-4}$ of the growth rate of the linear instability, which
is sufficient for the ""oblique"" instability to be the dominant cooling
mechanism of these pair beams. In particular, we show that previous estimates
of this rate ignored the exponential cutoff in the scattering amplitude at
large wavenumber and assumed that the damping of scattered waves entirely
depends on collisions, ignoring collisionless processes. We find that the total
wave energy eventually grows to approximate equipartition with the beam by
increasingly depositing energy into long wavelength modes. As we have not
included the effect of nonlinear wave-wave interactions on these long
wavelength modes, this scenario represents the ""worst-case"" scenario for the
oblique instability. As it continues to drain energy from the beam at a faster
rate than other processes, we conclude that the ""oblique"" instability is
sufficiently strong to make it the physically dominant cooling mechanism for
high-energy pair beams in the intergalactic medium.",1410.3797v2
2014-10-17,Hunting down systematics in baryon acoustic oscillations after cosmic high noon,"Future dark energy experiments will require better and more accurate
theoretical predictions for the baryonic acoustic oscillations (BAO) signature
in the spectrum of cosmological perturbations. Here, we use large N-body
simulations of the \LambdaCDM Planck cosmology to study any possible systematic
shifts and damping in BAO due to the impact of nonlinear gravitational growth
of structure, scale dependent and non-local bias, and redshift-space
distortions. The effect of cosmic variance is largely reduced by dividing the
tracer power spectrum by that from a BAO-free simulation starting with the same
phases. This permits us to study with unprecedented accuracy (better than 0.02%
for dark matter and 0.07% for low-bias halos) small shifts of the pristine BAO
wavenumbers towards larger k, and non-linear damping of BAO wiggles in the
power spectrum of dark matter and halo populations in the redshift range z=0-1.
For dark matter, we provide an accurate parametrization of the evolution of
\alpha as a function of the linear growth factor D(z). For halo samples, with
bias ranging from 1.2 to 2.8, we measure a typical BAO shift of ~0.25%,
observed in real-space, which does not show an appreciable evolution with
redshift within the uncertainties. Moreover, we report a constant shift as a
function of halo bias. We find a different evolution of the damping of the
acoustic feature in all halo samples as compared to dark matter with haloes
suffering less damping, and also find some weak dependence on bias. A larger
BAO shift and damping is measured in redshift-space which can be well explained
by linear theory due to redshift-space distortions. A clear modulation in phase
with the acoustic scale is observed in the scale-dependent halo bias due to the
presence of the baryonic acoustic oscillations.",1410.4684v2
2017-03-21,Using rf voltage induced ferromagnetic resonance to study the spin-wave density of states and the Gilbert damping in perpendicularly magnetized disks,"We study how the shape of the spinwave resonance lines in rf-voltage induced
FMR can be used to extract the spinwave density of states and the damping
within the precessing layer in nanoscale tunnel junctions that possess
perpendicular anisotropy. We work with a field applied along the easy axis to
preserve the uniaxial symmetry of the system. We describe the set-up to study
the susceptibility contributions of the spin waves in the field-frequency
space. We then identify the maximum device size above which the spinwaves can
no longer be studied in isolation as the linewidths of their responses make
them overlap. The rf-voltage induced signal is the sum of two voltages that
have comparable magnitudes: a first voltage that originates from the transverse
susceptibility and rectification by magnetoresistance and a second voltage that
arises from the non-linear longitudinal susceptibility and the resultant
time-averaged change of the micromagnetic configuration. The transverse and
longitudinal susceptibility signals have different dc bias dependences such
that they can be separated by measuring how the device rectifies the rf voltage
at different dc bias voltages. The transverse and longitudinal susceptibility
signals have different lineshapes; their joint studies can yield the Gilbert
damping of the free layer of the device with a degree of confidence that
compares well with standard FMR. Our method is illustrated on FeCoB-based free
layers in which the individual spin-waves can be sufficiently resolved only for
disk diameters below 200 nm. The resonance line shapes on devices with 90 nm
diameters are consistent with a Gilbert damping of 0.011. This damping of 0.011
exceeds the value of 0.008 measured on the unpatterned films, which indicates
that device-level measurements are needed for a correct evaluation of
dissipation.",1703.07310v2
2018-02-20,The chemical connection between damped Lyman-α systems and Local Group dwarf galaxies,"Abundances of the volatile elements S and Zn have now been measured in around
80 individual stars in the Sculptor dwarf spheroidal galaxy, covering the
metallicity range $-2.4\leq\text{[Fe/H]}\leq-0.9$. These two elements are of
particular interest as they are not depleted onto dust in gas, and their ratio,
[S/Zn], has thus commonly been used as a proxy for [$\alpha$/Fe] in Damped
Lyman-$\alpha$ systems. The S abundances in Sculptor are similar to other
$\alpha$-elements in this galaxy, consistent with S being mainly created in
core-collapse supernovae, but also having some contribution from supernovae
Type Ia. However, our results show that Zn and Fe do not trace all the same
nucleosynthetic production channels. In particular, (contrary to Fe) Zn is not
significantly produced by supernovae Type Ia. Thus, [S/Zn] cannot be reliably
used as a proxy for [$\alpha$/Fe]. We propose [O/S] as a function of [S/H] as a
possible alternative. At higher metallicities, the values of [S/Zn] measured in
Damped Lyman-$\alpha$ systems are inconsistent with those in local dwarf
galaxies, and are more compatible with the Milky Way disk. Low-metallicity
Damped Lyman-$\alpha$ systems are, however, consistent with the most metal-poor
stars in Local Group dwarf spheroidal galaxies. Assuming that the dust
depletions of S and Zn are negligible, our comparison indicates that the star
formation histories of Damped Lyman-$\alpha$ systems are on average different
from both the Milky Way and the Sculptor dwarf spheroidal galaxy.",1802.07325v5
2017-01-24,Influence of interlayer coupling on the spin torque driven excitations in a spin torque oscillator,"The influence of dynamic interlayer interactions on the spin torque driven
and damped excitations are illustrated for a three layer macrospin model system
that corresponds to a standard spin-torque oscillator. The free layer and a
synthetic antiferromagnetic (SyF) pinned layer of the spin-torque oscillator
are in-plane magnetized. In order to understand experimental results, numerical
simulations have been performed considering three types of interlayer
interactions: exchange interaction between the two magnetic layers of the SyF,
mutual spin torque between the top layer of the SyF and the free layer and
dipolar interaction between all three magnetic layers. It will be shown that
the dynamic dipolar coupling plays a predominant role. First, it leads to a
hybridization of the free layer and the SyF linear modes and through this gives
rise to a strong field dependence of the critical current. In particular, there
is a field range of enhanced damping in which much higher current is required
to drive the modes into steady state. This results in a gap in the excitation
spectrum. Second, the dynamic dipolar interaction is also responsible for the
non-linear interaction between the current driven steady state mode and the
damped modes of the system. Here one can distinguish: (i) a resonant
interaction that leads to a kink in the frequency-field and frequency-current
dispersions accompanied by a small hysteresis and a reduction of the linewidth
of the steady state mode and (ii) a non-resonant interaction that leads to a
strong frequency redshift of the damped mode. The results underline the strong
impact of interlayer coupling on the excitation spectra of spin-torque
oscillators and illustrate in a simple three mode model system how in the
non-linear regime the steady state and damped modes influence each other.",1701.06787v1
2017-04-07,Global Alfven Eigenmodes in the H-1 heliac,"Recent upgrades in H-1 power supplies have enabled the operation of the H-1
experiment at higher heating powers than previously attainable. A heating power
scan in mixed hydrogen/helium plasmas reveals a change in mode activity with
increasing heating power. At low power (<50 kW) modes with beta-induced Alfven
eigenmode (BAE) frequency scaling are observed. At higher power modes
consistent with an analysis of nonconventional Global Alfven Eigenmodes (GAEs)
are observed, the subject of this work. We have computed the mode continuum,
and identified GAE structures using the ideal MHD solver CKA and the
gyrokinetic code EUTERPE. An analytic model for ICRH-heated minority ions is
used to estimate the fast ion temperature from the hydrogen species. Linear
growth rate scans using a local flux surface stability calculation, LGRO, are
performed. These studies demonstrate growth from circulating particles whose
speed is significantly less than the Alfven speed, and are resonant with the
mode through harmonics of the Fourier decomposition of the strongly-shaped
heliac magnetic field. They reveal drive is possible with a small, hot
energetic tail of the hydrogen species. Local linear growth rate scans are also
complemented with global calculations from CKA and EUTERPE. These qualitatively
confirm the findings from the LGRO study, and show that the inclusion of finite
Larmor radius effects can reduce the growth rate by a factor of three, but do
not affect marginal stability. Finally, a study of damping of the global mode
with the thermal plasma is conducted, computing continuum, and the damping
arising from parallel electric fields. We find that continuum damping is of
order 0.1% for the configuration studied. The inclusion of resistivity lifts
the damping to 19%. Such large damping is consistent with experimental
observations that in absence of drive the mode decays rapidly (~0.1 ms).",1704.02089v1
2017-12-14,Scalar dark matter explanation of the DAMPE data in the minimal Left-Right symmetric model,"Left-Right symmetric model (LRSM) has been an attractive extension of the
Standard Model (SM) which can address the origin of parity violation in the SM
electroweak (EW) interactions, generate tiny neutrino masses, accommodate dark
matter (DM) candidates and provide a natural framework for baryogenesis through
leptogenesis. In this work we utilize the minimal LRSM to study the recently
reported DAMPE results of cosmic $e^+e^-$ spectrum which exhibits a tentative
peak around 1.4 TeV, while satisfying the current neutrino data. We propose to
explain the DAMPE peak with a complex scalar DM $\chi$ in two scenarios: 1)
$\chi\chi^* \to H_1^{++}H_1^{--} \to \ell_i^+\ell_i^+\ell_j^-\ell_j^-$; 2)
$\chi\chi^* \to H_{k}^{++}H_{k}^{--} \to \ell_i^+\ell_i^+\ell_j^-\ell_j^-$
accompanied by $\chi\chi^* \to H_1^+ H_1^- \to \ell_i^+ \nu_{\ell_i} \ell_j^-
\nu_{\ell_j}$ with $\ell_{i,j}=e,\mu,\tau$ and $k=1,2$. We fit the theoretical
prediction on $e^+e^-$ spectrum to relevant experimental data to determine the
scalar mass spectrum favored by the DAMPE excess. We also consider various
constraints from theoretical principles, collider experiments as well as DM
relic density and direct search experiments. We find that there are ample
parameter space which can interpret the DAMPE data while passing the
constraints. Our explanations, on the other hand, usually imply the existence
of other new physics at the energy scale ranging from $10^7 {\rm GeV}$ to
$10^{11} {\rm GeV}$. Collider tests of our explanations are also discussed.",1712.05351v3
2021-01-12,Phase Retrieval using Expectation Consistent Signal Recovery Algorithm based on Hypernetwork,"Phase retrieval (PR) is an important component in modern computational
imaging systems. Many algorithms have been developed over the past
half-century. Recent advances in deep learning have introduced new
possibilities for a robust and fast PR. An emerging technique called deep
unfolding provides a systematic connection between conventional model-based
iterative algorithms and modern data-based deep learning. Unfolded algorithms,
which are powered by data learning, have shown remarkable performance and
convergence speed improvement over original algorithms. Despite their
potential, most existing unfolded algorithms are strictly confined to a fixed
number of iterations when layer-dependent parameters are used. In this study,
we develop a novel framework for deep unfolding to overcome existing
limitations. Our development is based on an unfolded generalized expectation
consistent signal recovery (GEC-SR) algorithm, wherein damping factors are left
for data-driven learning. In particular, we introduce a hypernetwork to
generate the damping factors for GEC-SR. Instead of learning a set of optimal
damping factors directly, the hypernetwork learns how to generate the optimal
damping factors according to the clinical settings, thereby ensuring its
adaptivity to different scenarios. To enable the hypernetwork to adapt to
varying layer numbers, we use a recurrent architecture to develop a dynamic
hypernetwork that generates a damping factor that can vary online across
layers. We also exploit a self-attention mechanism to enhance the robustness of
the hypernetwork. Extensive experiments show that the proposed algorithm
outperforms existing ones in terms of convergence speed and accuracy and still
works well under very harsh settings, even under which many classical PR
algorithms are unstable.",2101.04348v2
2017-11-30,Scalar dark matter interpretation of the DAMPE data with U(1) gauge interactions,"Recently, DAMPE experiment released the new measurement of the total cosmic
$e^+e^-$ flux between 25 GeV and 4.6 TeV which indicates a spectral softening
at around 0.9 TeV and a tentative peak at around 1.4 TeV. We utilize the scalar
dark matter (DM) annihilation scenario to explain the DAMPE peak by extending
$G_{SM}\equiv SU(3)_C \times SU(2)_L \times U(1)_Y$ with additional $U(1)$
gauge symmetries while keeping anomaly free to generate $\chi \chi \to Z^\prime
Z^\prime \to \ell\bar{\ell}\ell^\prime\overline{\ell^\prime}$, where $\chi,
Z^\prime, \ell^{(^\prime)}$ denote the scalar DM, the new gauge boson and
$\ell^{(^\prime)}=e,\mu,\tau$, respectively, with $m_\chi \sim m_{Z^\prime}
\sim 2 \times 1.5$ (TeV). We first illustrate that the minimal framework
$G_{SM} \times U(1)_{Y^\prime}$ with the above mass choices can explain the
DAMPE excess but has been excluded by LHC constraints from the $Z^\prime$
searches. Then we study a non-minimal framework $G_{SM} \times U(1)_{Y^\prime}
\times U(1)_{Y^{\prime \prime}}$ in which $U(1)_{Y^{\prime \prime}}$ mixes with
$U(1)_{Y^\prime}$. We show that such a framework can interpret the DAMPE data
while passing other constraints including the DM relic abundance, DM direct
detection and collider bounds. We also investigate the predicted $e^+e^-$
spectrum in this framework and find that the mass splitting $\Delta m = m_\chi
- m_{Z'}$ should be less than about 17 GeV to produce the peak-like structure.",1711.11452v2
2019-01-12,GW170817 implications on the frequency and damping time of f-mode oscillations of neutron stars,"Within a minimum model for neutron stars consisting of nucleons, electrons
and muons at $\beta$-equilibrium using about a dozen Equation of States (EOSs)
from microscopic nuclear many-body theories and 40,000 EOSs randomly generated
using an explicitly isospin-dependent parametric EOS model for high-density
neutron-rich nucleonic matter within its currently known uncertainty range, we
study correlations among the f-mode frequency, its damping time and the tidal
deformability as well as the compactness of neutron stars. Except for quark
stars, both the f-mode frequency and damping time of canonical neutron stars
are found to scale with the tidal deformability independent of the EOSs used.
Applying the constraint on the tidal deformability of canonical neutron stars
$\Lambda_{1.4}=190^{+390}_{-120}$ extracted by the LIGO+VIRGO Collaborations
from their improved analyses of the GW170817 event, the f-mode frequency and
its damping time of canonical neutron stars are limited to 1.67 kHz - 2.18 kHz
and 0.155 s - 0.255 s, respectively, providing a useful guidance for the
ongoing search for gravitational waves from the f-mode oscillations of isolated
neutron stars. Moreover, assuming either or both the f-mode frequency and its
damping time will be measured precisely in future observations with advanced
gravitational wave detectors, we discuss how information about the mass and/or
radius as well as the still rather elusive nuclear symmetry energies at
supra-saturation densities may be extracted.",1901.03779v2
2019-01-27,"An introductory guide to fluid models with anisotropic temperatures Part 2 -- Kinetic theory, Padé approximants and Landau fluid closures","In Part 2 of our guide to collisionless fluid models, we concentrate on
Landau fluid closures. These closures were pioneered by Hammett and Perkins and
allow for the rigorous incorporation of collisionless Landau damping into a
fluid framework. It is Landau damping that sharply separates traditional fluid
models and collisionless kinetic theory, and is the main reason why the usual
fluid models do not converge to the kinetic description, even in the
long-wavelength low-frequency limit. We start with a brief introduction to
kinetic theory, where we discuss in detail the plasma dispersion function
$Z(\zeta)$, and the associated plasma response function $R(\zeta)=1+\zeta
Z(\zeta)=-Z'(\zeta)/2$. We then consider a 1D (electrostatic) geometry and make
a significant effort to map all possible Landau fluid closures that can be
constructed at the 4th-order moment level. These closures for parallel moments
have general validity from the largest astrophysical scales down to the Debye
length, and we verify their validity by considering examples of the (proton and
electron) Landau damping of the ion-acoustic mode, and the electron Landau
damping of the Langmuir mode. We proceed by considering 1D closures at
higher-order moments than the 4th-order, and as was concluded in Part 1, this
is not possible without Landau fluid closures. We show that it is possible to
reproduce linear Landau damping in the fluid framework to any desired
precision, thus showing the convergence of the fluid and collisionless kinetic
descriptions. We then consider a 3D (electromagnetic) geometry in the
gyrotropic (long-wavelength low-frequency) limit and map all closures that are
available at the 4th-order moment level. In the Appendix A, we provide
comprehensive tables with Pad\'e approximants of $R(\zeta)$ up to the 8th-pole
order, with many given in an analytic form.",1901.09360v2
2019-01-28,Revisit of non-linear Landau damping for electrostatic instability driven by blazar-induced pair beams,"We revisit the effect of non-linear Landau (NL) damping on the electrostatic
instability of blazar-induced pair beams, using a realistic pair-beam
distribution. We employ a simplified 2D model in ${\bf k}$-space to study the
evolution of the electric-field spectrum and to calculate the relaxation time
of the beam. We demonstrate that the 2D model is an adequate representation of
the 3D physics. We find that non-linear Landau damping, once it operates
efficiently, transports essentially the entire wave energy to small wavenumbers
where wave driving is weak or absent. The relaxation time also strongly depends
on the IGM temperature, $T_\mathrm{IGM}$, and for $T_\mathrm{IGM}\ll10$ eV, and
in the absence of any other damping mechanism, the relaxation time of the pair
beam is longer than the inverse Compton (IC) scattering time. The weak
late-time beam energy losses arise from the accumulation of wave energy at
small $k$, that non-linearly drains the wave energy at the resonant
$\mathbf{k}$ of the pair-beam instability. Any other dissipation process
operating at small $k$ would reduce that wave-energy drain and hence lead to
stronger pair-beam energy losses. As an example, collisions reduce the
relaxation time by an order of magnitude, although their rate is very small.
Other non-linear processes, such as the modulation instability, could provide
additional damping of the non-resonant waves and dramatically reduce the
relaxation time of the pair beam. An accurate description of the spectral
evolution of the electrostatic waves is crucial for calculating the relaxation
time of the pair beam.",1901.09640v3
2019-08-08,Annihilation of topological solitons in magnetism with spin wave burst finale: The role of nonequilibrium electrons causing nonlocal damping and spin pumping over ultrabroadband frequency range,"We not only reproduce burst of short-wavelength spin waves (SWs) observed in
recent experiment [S. Woo et al., Nat. Phys. 13, 448 (2017)] on
magnetic-field-driven annihilation of two magnetic domain walls (DWs) but,
furthermore, we predict that this setup additionally generates highly unusual}
pumping of electronic spin currents in the absence of any bias voltage. Prior
to the instant of annihilation, their power spectrum is ultrabroadband, so they
can be converted into rapidly changing in time charge currents, via the inverse
spin Hall effect, as a source of THz radiation of bandwidth $\simeq 27$ THz
where the lowest frequency is controlled by the applied magnetic field. The
spin pumping stems from time-dependent fields introduced into the quantum
Hamiltonian of electrons by the classical dynamics of localized magnetic
moments (LMMs) comprising the domains. The pumped currents carry spin-polarized
electrons which, in turn, exert backaction on LMMs in the form of nonlocal
damping which is more than twice as large as conventional local Gilbert
damping. The nonlocal damping can substantially modify the spectrum of emitted
SWs when compared to widely-used micromagnetic simulations where conduction
electrons are completely absent. Since we use fully microscopic (i.e.,
Hamiltonian-based) framework, self-consistently combining time-dependent
electronic nonequilibrium Green functions with the Landau-Lifshitz-Gilbert
equation, we also demonstrate that previously derived phenomenological formulas
miss ultrabroadband spin pumping while underestimating the magnitude of
nonlocal damping due to nonequilibrium electrons.",1908.03194v5
2019-11-22,"Role of Element-Specific Damping on the Ultrafast, Helicity-Independent All-Optical Switching Dynamics in Amorphous (Gd,Tb)Co Thin Films","Ultrafast control of the magnetization in ps timescales by fs laser pulses
offers an attractive avenue for applications such as fast magnetic devices for
logic and memory. However, ultrafast helicity-independent all-optical switching
(HI-AOS) of the magnetization has thus far only been observed in Gd-based,
ferrimagnetic amorphous (\textit{a}-) rare earth-transition metal
(\textit{a}-RE-TM) systems, and a comprehensive understanding of the reversal
mechanism remains elusive. Here, we report HI-AOS in ferrimagnetic
\textit{a}-Gd$_{22-x}$Tb$_x$Co$_{78}$ thin films, from x = 0 to x = 18, and
elucidate the role of Gd in HI-AOS in \textit{a}-RE-TM alloys and multilayers.
Increasing Tb content results in increasing perpendicular magnetic anisotropy
and coercivity, without modifying magnetization density, and slower
remagnetization rates and higher critical fluences for switching but still
shows picosecond HI-AOS. Simulations of the atomistic spin dynamics based on
the two-temperature model reproduce these results qualitatively and predict
that the lower damping on the RE sublattice arising from the small spin-orbit
coupling of Gd (with $L = 0$) is instrumental for the faster dynamics and lower
critical fluences of the Gd-rich alloys. Annealing
\textit{a}-Gd$_{10}$Tb$_{12}$Co$_{78}$ leads to slower dynamics which we argue
is due to an increase in damping. These simulations strongly indicate that
acounting for element-specific damping is crucial in understanding HI-AOS
phenomena. The results suggest that engineering the element specific damping of
materials can open up new classes of materials that exhibit low-energy,
ultrafast HI-AOS.",1911.09803v3
2020-06-08,Hysteretic depinning of a particle in a periodic potential: Phase diagram and criticality,"We consider a massive particle driven with a constant force in a periodic
potential and subjected to a dissipative friction. As a function of the drive
and damping, the phase diagram of this paradigmatic model is well known to
present a pinned, a sliding, and a bistable regime separated by three distinct
bifurcation lines. In physical terms, the average velocity $v$ of the particle
is nonzero only if either (i) the driving force is large enough to remove any
stable point, forcing the particle to slide, or (ii) there are local minima but
the damping is small enough, below a critical damping, for the inertia to allow
the particle to cross barriers and follow a limit cycle; this regime is
bistable and whether $v > 0$ or $v = 0$ depends on the initial state. In this
paper, we focus on the asymptotes of the critical line separating the bistable
and the pinned regimes. First, we study its behavior near the ""triple point""
where the pinned, the bistable, and the sliding dynamical regimes meet. Just
below the critical damping we uncover a critical regime, where the line
approaches the triple point following a power-law behavior. We show that its
exponent is controlled by the normal form of the tilted potential close to its
critical force. Second, in the opposite regime of very low damping, we revisit
existing results by providing a simple method to determine analytically the
exact behavior of the line in the case of a generic potential. The analytical
estimates, accurately confirmed numerically, are obtained by exploiting exact
soliton solutions describing the orbit in a modified tilted potential which can
be mapped to the original tilted washboard potential. Our methods and results
are particularly useful for an accurate description of underdamped nonuniform
oscillators driven near their triple point.",2006.04912v2
2020-09-14,Large field-like torque in amorphous Ru2Sn3 originated from the intrinsic spin Hall effect,"We investigated temperature dependent current driven spin-orbit torques in
magnetron sputtered Ru2Sn3 (4 and 10 nm) /Co20Fe60B20 (5 nm) layered structures
with in-plane magnetic anisotropy. The room temperature damping-like and
field-like spin torque efficiencies of the amorphous Ru2Sn3 films were measured
to be 0.14 +- 0.008 (0.07 +- 0.012) and -0.03 +- 0.006 (-0.20 +- 0.009), for
the 4 (10 nm) films respectively, by utilizing the second harmonic Hall
technique. The large field-like torque in the relatively thicker Ru2Sn3 (10 nm)
thin film is unique compared to the traditional spin Hall materials interfaced
with thick magnetic layers with in-plane magnetic anisotropy which typically
have dominant damping-like and negligible field-like torques. Additionally, the
observed room temperature field-like torque efficiency in Ru2Sn3 (10 nm)/CoFeB
(5 nm) is up to three times larger than the damping-like torque (-0.20 +- 0.009
and 0.07 +- 0.012, respectively) and thirty times larger at 50 K (-0.29 +-
0.014 and 0.009 +- 0.017, respectively). The temperature dependence of the
field-like torques show dominant contributions from the intrinsic spin Hall
effect while the damping-like torques show dominate contributions from the
extrinsic spin Hall effects, skew scattering and side jump. Through macro-spin
calculations, we found that including field-like torques on the order or larger
than the damping-like torque can reduce the switching critical current and
decrease magnetization procession for a perpendicular ferromagnetic layer.",2009.06711v2
2021-06-18,Sloshing dynamics of liquid tank with built-in buoys for wave energy harvesting,"This paper proposes a novel design of liquid tank with built-in buoys for
wave energy harvesting, named the 'sloshing wave energy converter (S-WEC)'.
When the tank is oscillated by external loads (such as ocean waves), internal
liquid sloshing is activated, and the mechanical energy of sloshing waves can
be absorbed by the power take-off (PTO) system attached to these buoys. A
fully-nonlinear numerical model is established based on the boundary element
method for a systematic investigation on dynamic properties of the proposed
S-WEC. A motion decoupling algorithm based on auxiliary functions is developed
to solve the nonlinear interaction of sloshing waves and floating buoys in the
tank. An artificial damping model is introduced to reflect viscous effects of
the sloshing liquid. Physical experiments are carried out on a scaled S-WEC
model to validate the mathematical and numerical methodologies. Natural
frequencies of the S-WEC system are first investigated through spectrum
analyses on motion histories of the buoy and sloshing liquid. The viscous
damping strength is identified through comparisons with experimental
measurements. Effects of the PTO damping on power generation characteristics of
S-WEC is further explored. An optimal PTO damping can be found for each
excitation frequency, leading to the maximisation of both the power generation
and conversion efficiency of the buoy. To determine a constant PTO damping for
engineering design, a practical approach based on diagram analyses is proposed.
Effects of the buoy's geometry on power generation characteristics of the S-WEC
are also investigated. In engineering practice, the present design of S-WEC can
be a promising technical solution of ocean wave energy harvesting, based on its
comprehensive advantages on survivability enhancement, metal corrosion or
fouling organism inhibition, power generation stability and efficiency, and so
on.",2106.10005v1
2024-03-22,Investigating the Relationship between Simulation Parameters and Flow Variables in Simulating Atmospheric Gravity Waves in Wind Energy Applications,"Wind farms, particularly offshore clusters, are becoming larger than ever
before. Besides influencing wind farms and local meteorology downstream, large
wind farms can trigger atmospheric gravity waves in the inversion layer and the
free atmosphere aloft. Wind farm-induced gravity waves can cause adverse
pressure gradients upstream of the wind farm, that contribute to the global
blockage effect, and favorable pressure gradients above and downstream of the
wind farm that enhance wake recovery.
  Numerical modeling is a powerful means of studying wind farm-induced
atmospheric gravity waves, but it comes with the challenge of handling spurious
reflections of these waves from domain boundaries. Approaches like radiation
boundary conditions and forcing zones are used to avoid the reflections.
However, the simulation setup heavily relies on ad-hoc processes. For instance,
the widely used Rayleigh damping method requires ad-hoc tuning to acquire a
setup only applicable to a particular case. To surmount this hurdle, we conduct
a systematic LES study for flow over a 2D hill and through wind farm canopies
that explores the dependence of domain size and damping layer setup on
parameters driving linearly stratified atmospheric flows.
  Mainly the internal waves in the free atmosphere reflect from the boundaries,
therefore by simulation linearly stratified conditions we focus on internal
waves only. The Froude number drives most of the internal wave properties, such
as wavelengths, amplitude, and direction. Therefore, the domain sizing and
Rayleigh damping layer setup mainly depends on the Froude number. We
anticipated the effective wavelengths to be the correct length scale to size
the domain and damping layer thickness. Also, the damping coefficient is scaled
with Brunt-V\""ais\""al\""a frequency.",2403.18863v1
1995-05-25,Properties of a possible class of particles able to travel faster than light,"The apparent Lorentz invariance of the laws of physics does not imply that
space-time is indeed minkowskian. Matter made of solutions of Lorentz-invariant
equations would feel a relativistic space-time even if the actual space-time
had a quite different geometry (i.e. a galilean space-time). A typical example
is provided by sine-Gordon solitons in a galilean world. A ""sub-world""
restricted to such solitons would be ""relativistic"", with the critical speed of
solitons playing the role of the speed of light. Only the study of the deep
structure of matter will unravel the actual geometry of space and time, which
we expect to be scale-dependent and determined by the properties of matter
itself. If Lorentz invariance is a property of equations describing a sector of
matter at a given scale, an absolute frame (the ""vacuum rest frame"") may exist
without contradicting the minkowskian sctructure of the space-time felt by
ordinary particles. But c, the speed of light, will not necessarily be the only
critical speed in vacuum: for instance, a superluminal sector of matter may
exist related to new degrees of freedom not yet discovered experimentally. Such
particles would not be tachyons: they may feel a different minkowskian
space-time with a critical speed larger than c and behave kinematically like
ordinary particles apart from the difference in critical speed. At speed larger
than c , they are expected to release ""Cherenkov"" radiation (ordinary
particles) in vacuum. We present a discussion of possible physical (theoretical
experimental) and cosmological implications of such a scenario, assuming that
the superluminal sector couples weakly to ordinary matter.",9505117v1
1999-09-03,Relativistic Winds from Compact Gamma-ray Sources: I. Radiative Acceleration in the Klein-Nishina Regime,"We consider the radiative acceleration to relativistic bulk velocities of a
cold, optically thin plasma which is exposed to an external source of
gamma-rays. The flow is driven by radiative momentum input to the gas, the
accelerating force being due to Compton scattering in the relativistic
Klein-Nishina limit. The bulk Lorentz factor of the plasma, Gamma, derived as a
function of distance from the radiating source, is compared with the
corresponding result in the Thomson limit. Depending on the geometry and
spectrum of the radiation field, we find that particles are accelerated to the
asymptotic Lorentz factor at infinity much more rapidly in the relativistic
regime; and the radiation drag is reduced as blueshifted, aberrated photons
experience a decreased relativistic cross section and scatter preferentially in
the forward direction. The random energy imparted to the plasma by gamma-rays
can be converted into bulk motion if the hot particles execute many Larmor
orbits before cooling. This `Compton afterburn' may be a supplementary source
of momentum if energetic leptons are injected by pair creation, but can be
neglected in the case of pure Klein-Nishina scattering. Compton drag by
side-scattered radiation is shown to be more important in limiting the bulk
Lorentz factor than the finite inertia of the accelerating medium. The
processes discussed here may be relevant to a variety of astrophysical
situations where luminous compact sources of hard X- and gamma-ray photons are
observed, including active galactic nuclei, galactic black hole candidates, and
gamma-ray bursts.",9909060v2
1999-09-17,Gamma-Ray Bursts as Internal Shocks Caused By Deceleration,"Gamma-ray bursts (GRBs) have been thought to originate from internal shocks
that occur about 10^{15} cm from a central site. The shells responsible for
these shocks merge together and undergo an external shock at about 10^{17} cm,
producing the afterglows. We include deceleration in our model of internal
shocks and find that, for values of the Lorentz factor greater than 10^3,
deceleration is an effective catalyst for converting the bulk motion energy
into radiation during the GRB phase. Substantial internal energy occurs because
other shells run into the back of the first shell which has decelerated and
because the first shell must energize the interstellar medium. Whereas internal
shocks without deceleration are about 25% efficient, we can convert up to 85%
of the bulk motion energy during the GRB phase. We demonstrate that the
resulting time history can have three components. The first is due to internal
shocks, excluding those that involve the first shell. This component produces
narrow peaks throughout the time history. The second is due to internal shocks
involving the first shell, and it produces progressively wider and wider peaks
but they tend to be hidden in a slowly varying background in the event. The
third component is from energizing the interstellar medium. It is very smooth
and may contribute mostly to a lower energy bandpass than the BATSE experiment.
There have been claims of upper limits on the possible Lorentz factor because
the deceleration must occur at greater radii than the internal shocks to avoid
making progressively wider peaks. We do not find this to be the case, and the
Lorentz factor (and efficiency) can be much larger.",9909299v1
2002-09-27,The Effect of External Winds on Relativistic Jets,"Relativistic jets in Galactic superluminals and extragalactic AGN may be
surrounded by a wind near to the central engine. Theoretical analysis and
numerical simulation reveal considerable stabilization of relativistic jet flow
by a wind to helical and higher order asymmetric modes of jet distortion. When
velocities are measured in the source (inlet) frame, reduction in the absolute
velocity difference between jet and wind, $\Delta v = v_{jet} - v_{wnd}$,
provides stabilization in addition to stabilization provided by a high jet
Lorentz factor, but a high Lorentz factor wind is not needed to stabilize a
high Lorentz factor jet. However, the fundamental pinch mode is not similarly
affected and knots with spacing a few times the jet radius are anticipated to
develop in such flows. Thus, we identify a mechanism that can suppress large
scale asymmetric structures while allowing axisymmetric structures to develop.
Relativistic jets surrounded by outflowing winds will be more stable than if
surrounded by a stationary or backflowing external medium. Knotty structures
along a straight jet like that in 3C 175 could be triggered by pinching of an
initially low Mach number jet surrounded by a suitable wind. As the jet enters
the radio lobe, suppression of any surrounding outflow or backflow associated
with the high pressure lobe triggers exponential growth of helical twisting.",0209593v1
2003-12-03,Ultra-Relativistic Magneto-Hydro-Dynamic Jets in the context of Gamma Ray Bursts,"We present a detailed numerical study of the dynamics and evolution of
ultrarelativistic magnetohydrodynamic jets in the black hole-disk system under
extreme magnetization conditions. We find that Lorentz factors of up to 3000
are achieved and derived a modifiedMichel scaling (Gamma ~ sigma) which allows
for a wide variation in the flow Lorentz factor. Pending contamination induced
by mass-entrainment, the linear Michel scaling links modulations in the
ultrarelativistic wind to variations in mass accretion in the disk for a given
magnetization. The jet is asymptotically dominated by the toroidal magnetic
field allowing for efficient collimation. We discuss our solutions (jets) in
the context of Gamma ray bursts and describe the relevant features such as the
high variability in the Lorentz factor and how high collimation angles (~ 0-5
degrees), or cylindrical jets, can be achieved. We isolate a jet instability
mechanism we refer to as the ""bottle-neck"" instability which essentially relies
on a high magnetization and a recollimation of the magnetic flux surfaces. The
instability occurs at large radii where any dissipation of the magnetic energy
into radiation would in principle result in an optically thin emission.",0312090v1
2004-04-04,GeV and higher energy photon interactions in gamma-ray burst fireballs and surroundings,"We have calculated the opacities and secondary production mechanisms of high
energy photons arising in gamma-ray burst internal shocks, using exact
cross-sections for the relevant processes. We find that for reasonable choices
of parameters, photons in the range of 10's to 100's of GeV may be emitted in
the prompt phase. Photons above this range are subject to electron-positron
pair production with fireball photons and would be absent from the spectrum
escaping the gamma-ray burst. We find that, in such cases, the fireball becomes
optically thin again at ultra-high energies ($\gtrsim$ PeV). On the other hand,
for sufficiently large fireball bulk Lorentz factors, the fireball is optically
thin at all energies. Both for $\gamma\gamma$ self-absorbed and optically thin
cases, the escaping high energy photons can interact with infra-red and
microwave background photons to produce delayed secondary photons in the
GeV-TeV range. These may be observable with GLAST, or at low redshifts with
ground-based air Cherenkov telescopes. Detection of the primary prompt spectrum
constrains the bulk Lorentz factor, while detection of delayed secondary
gamma-rays would provide a consistency check for the primary spectrum and the
bulk Lorentz factor as well as constraints on the intergalactic magnetic field
strength.",0404076v2
2004-10-29,Modeling the 3C 120 Radio Jet from 1 to 30 Milliarcseconds,"The predicted spatial development of helical structures along an expanding
jet are used to model observed structures and motions in the 3C 120 jet. Proper
motions of helical components associated with the pattern and of other
components that move through the pattern provide estimates of flow and helical
pattern speeds. Theoretical modeling allows determination of sound speeds as a
function of jet viewing angle. Jet morphology argues against viewing angles
larger than 12 deg. At a 12 deg viewing angle the most likely scenario involves
a decline in jet sound speed from c/3 < a_j < c/1.7 at ~0.5 mas from the core
to 0.1c < a_j < 0.25c at ~25 mas from the core accompanied by some acceleration
in the jet flow from Lorentz factor < 5 to Lorentz factor > 7. At smaller
viewing angles the jet sound speed is lower and at a 6 deg viewing angle the
jet sound speed is about a factor 2 less but the flow Lorentz factor is
comparable. The decline in radio intensity is on the order of what would be
associated with isothermal jet expansion. Knot interknot intensity variations
are greater than would be expected from adiabatic compressions associated with
the helical twist and we infer the presence of a shock along the leading edge
of the helical twist. Our results imply that the macroscopic heating of the
expanding jet fluid is less than the microscopic energization of the
synchrotron radiating relativistic electrons.",0410720v1
2005-05-23,High Energy Afterglow Emission from Giant Flares of Soft Gamma-Ray Repeaters: The Case of the 2004 December 27 Event from SGR 1806-20,"We discuss the high enegry afterglow emission (including high energy photons,
neutrinos and cosmic rays) following the 2004 December 27 Giant Flare from SGR
1806-20. If the initial outflow is relativistic with a bulk Lorentz factor
\Gamma_0\sim {\rm tens}, the high-energy tail of the synchrotron emission from
electrons in the forward shock region gives rise to a prominent sub-GeV
emission, if the electron spectrum is hard enough and if the intial Lorentz
factor is high enough. This signal could serve as a diagnosis of the initial
Lorentz factor of the giant flare outflow. This component is potentially
detectable by GLAST if a similar giant flare occurs in the GLAST era. With the
available 10 MeV data, we constrain that \Gamma_0 < 50 if the electron
distribution is a single power law. For a broken power law distribution of
electrons, a higher \Gamma_0 is allowed. At energies higher than 1 GeV, the
flux is lower because of a high energy cut off of the synchrotron emission
component. The synchrotron self-Compton emission component and the inverse
Compton scattering component off the photons in the giant flare oscillation
tail are also considered, but they are found not significant given a moderate
\Gamma_0 (e.g. \leq 10). The forward shock also accelerates cosmic rays to the
maximum energy 10^{17}eV, and generate neutrinos with a typical energy
10^{14}eV through photomeson interaction with the X-ray tail photons. However,
they are too weak to be detectable.",0505483v2
2006-04-06,A Simple Two-Parameter Characterization of Gamma-Ray Burst Time Histories,"A simple scheme delineates Long GRBs with similar time histories using the
Internal Luminosity Function power-law index and the spectral lag. Several
generalizations are made about time history morphologies: 1) GRBs with long
spectral lags contain fewer pulses that are broader than those found in bursts
with short spectral lags, 2) short-lag bursts with small ILF power-law indices
have many narrow pulses and are highly variable, while long-lag bursts with
small ILF power-law indices are characterized by broad, smooth pulses and have
low variability.
  GRB time history morphologies primarily identify intrinsic rather than
extrinsic characteristics based on correlations with gamma-ray luminosity,
afterglow luminosity, and numbers of pulses. These characteristics result
because internal relativistic effects due to bulk Lorentz factor are larger
than cosmological effects, and because the numbers and shapes of pulses
indicate different efficiencies and forms of GRB energy release.
  Single-pulsed GRBs are characterized either by large ILF power indices
(indicating a range of jet opening angles and Lorentz factors, with a FRED
pulse shape), or they have long lags (large jet opening angles with low Lorentz
factors, with either a FRED pulse shape or an unpeaked, smooth pulse shape).
They also have lower-luminosity afterglows than multi-pulsed GRBs. GRBs with
simple time histories are often associated with Type Ibc supernovae. This
suggests that some single-pulsed GRBs contain single, beamed blast waves that
are similar to and have characteristics that overlap with those of many
supernovae. Such a connection may not exist between multi-pulsed GRBs and
supernovae.",0604151v1
2006-05-31,"Refining a relativistic, hydrodynamic solver: Admitting ultra-relativistic flows","We have undertaken the simulation of hydrodynamic flows with bulk Lorentz
factors in the range 10^2--10^6. We discuss the application of an existing
relativistic, hydrodynamic primitive-variable recovery algorithm to a study of
pulsar winds, and, in particular, the refinement made to admit such
ultra-relativistic flows. We show that an iterative quartic root finder breaks
down for Lorentz factors above 10^2 and employ an analytic root finder as a
solution. We find that the former, which is known to be robust for Lorentz
factors up to at least 50, offers a 24% speed advantage. We demonstrate the
existence of a simple diagnostic allowing for a hybrid primitives recovery
algorithm that includes an automatic, real-time toggle between the iterative
and analytical methods. We further determine the accuracy of the iterative and
hybrid algorithms for a comprehensive selection of input parameters and
demonstrate the latter's capability to elucidate the internal structure of
ultra-relativistic plasmas. In particular, we discuss simulations showing that
the interaction of a light, ultra-relativistic pulsar wind with a slow, dense
ambient medium can give rise to asymmetry reminiscent of the Guitar nebula
leading to the formation of a relativistic backflow harboring a series of
internal shockwaves. The shockwaves provide thermalized energy that is
available for the continued inflation of the PWN bubble. In turn, the bubble
enhances the asymmetry, thereby providing positive feedback to the backflow.",0606012v2
2006-10-07,Origin of solar torsional oscillations,"Helioseismology has revealed many details of solar differential rotation and
also its time variation, known as torsional oscillations. So far there is no
generally accepted theoretical explanation for torsional oscillations, even
though a close relation to the solar activity cycle is evident. On the
theoretical side non-kinematic dynamo models (including the Lorentz force
feedback on differential rotation) have been used to explain torsional
oscillations. In this paper we use a slightly different approach by forcing
torsional oscillations in a mean field differential rotation model. Our aim is
not a fully self-consistent model but rather to point out a few general
properties of torsional oscillations and their possible origin that are
independent from a particular dynamo model. We find that the poleward
propagating high latitude branch of the torsional oscillations can be explained
as a response of the coupled differential rotation / meridional flow system to
periodic forcing in mid-latitudes, of either mechanical (Lorentz force) or
thermal nature. The speed of the poleward propagation sets constraints on the
value of the turbulent viscosity in the solar convection zone to be less than
3x10^8 m^2/s. We also show that the equatorward propagating low latitude branch
is very unlikely a consequence of mechanical forcing (Lorentz force) alone, but
rather of thermal origin due to the Taylor-Proudman theorem.",0610221v1
1996-07-31,Thermodynamic formalism and localization in Lorentz gases and hopping models,"The thermodynamic formalism expresses chaotic properties of dynamical systems
in terms of the Ruelle pressure $\psi(\beta)$. The inverse-temperature like
variable $\beta$ allows one to scan the structure of the probability
distribution in the dynamic phase space. This formalism is applied here to a
Lorentz Lattice Gas, where a particle moving on a lattice of size $L^d$
collides with fixed scatterers placed at random locations. Here we give
rigorous arguments that the Ruelle pressure in the limit of infinit e systems
has two branches joining with a slope discontinuity at $\beta = 1$. The low and
high $\beta$--branches correspond to localization of trajectories on
respectively the ``most chaotic'' (highest density) region, and the ``most
deterministic'' (lowest density) region, i.e. $\psi(\beta)$ is completely
controlled by rare fluctuations in the distribution of scatterers on the
lattice, and it does not carry any information on the global structure of the
static disorder.
  As $\beta$ approaches unity from either side, a localization-delocalization
transition leads to a state where trajectories are extended and carry
information on transport properties. At finite $L$ the narrow region around
$\beta = 1$ where the trajectories are extended scales as $(\ln L)^{-\alpha}$,
where $\alpha$ depends on the sign of $1-\beta$, if $d>1$, and as $(L\ln
L)^{-1}$ if $d=1$. This result appears to be general for diffusive systems with
static disorder, such as random walks in random environments or for the
continuous Lorentz gas. Other models of random walks on disordered lattices,
showing the same phenomenon, are discussed.",9607019v1
2000-02-09,"Long-time-tail Effects on Lyapunov Exponents of a Random, Two-dimensional Field-driven Lorentz Gas","We study the Lyapunov exponents for a moving, charged particle in a
two-dimensional Lorentz gas with randomly placed, non-overlapping hard disk
scatterers placed in a thermostatted electric field, $\vec{E}$. The low density
values of the Lyapunov exponents have been calculated with the use of an
extended Lorentz-Boltzmann equation. In this paper we develop a method to
extend these results to higher density, using the BBGKY hierarchy equations and
extending them to include the additional variables needed for calculation of
Lyapunov exponents. We then consider the effects of correlated collision
sequences, due to the so-called ring events, on the Lyapunov exponents. For
small values of the applied electric field, the ring terms lead to
non-analytic, field dependent, contributions to both the positive and negative
Lyapunov exponents which are of the form ${\tilde{\epsilon}}^{2}
\ln\tilde{\epsilon}$, where $\tilde{\epsilon}$ is a dimensionless parameter
proportional to the strength of the applied field. We show that these
non-analytic terms can be understood as resulting from the change in the
collision frequency from its equilibrium value, due to the presence of the
thermostatted field, and that the collision frequency also contains such
non-analytic terms.",0002132v1
1999-10-25,Equation of motion in a scalar model of gravity,"A scalar model of gravity is considered. We propose Lorentz invariant field
equation $\square f = k\eta_{ab}f_{,a}f_{,b}$. The aim of this model is to get,
approximately, Newton's law of gravity. It is shown that $f=-\frac
1k\ln(1-k\frac mr)$ is the unique spherical symmetric static solution of the
field equation. $f$ is taken to be the field of a particle at the origin,
having the mass $m$. The field of a particle moving with a constant velocity is
taken to be the appropriate Lorentz transformation of $f$. The field $F$ of $N$
particles moving on trajectories ${\psi_j(t)}$ is taken to be, to first order,
the superposition of the fields of the particles, where the instantaneous
Lorentz transformation of the fields pertaining to the $j$-th particle is
${\dot\psi_j(t)}$. When this field is inserted to the field equation the
outcome is singular at $({\psi_j(t)},t)$. The singular terms of the l.h.s. and
of the r.h.s. are both $O(R^{-2})$. The only way to reduce the singularity in
the field equation is by postulating Newton's law of force. It is hoped that
this model will be generalized to system of equations that are covariant under
general diffeomorphism.",9910083v1
2000-06-28,Lorentzian regularization and the problem of point-like particles in general relativity,"The two purposes of the paper are (1) to present a regularization of the
self-field of point-like particles, based on Hadamard's concept of ``partie
finie'', that permits in principle to maintain the Lorentz covariance of a
relativistic field theory, (2) to use this regularization for defining a model
of stress-energy tensor that describes point-particles in post-Newtonian
expansions (e.g. 3PN) of general relativity. We consider specifically the case
of a system of two point-particles. We first perform a Lorentz transformation
of the system's variables which carries one of the particles to its rest frame,
next implement the Hadamard regularization within that frame, and finally come
back to the original variables with the help of the inverse Lorentz
transformation. The Lorentzian regularization is defined in this way up to any
order in the relativistic parameter 1/c^2. Following a previous work of ours,
we then construct the delta-pseudo-functions associated with this
regularization. Using an action principle, we derive the stress-energy tensor,
made of delta-pseudo-functions, of point-like particles. The equations of
motion take the same form as the geodesic equations of test particles on a
fixed background, but the role of the background is now played by the
regularized metric.",0006100v2
2002-05-16,Conservation Laws in Doubly Special Relativity,"Motivated by various theoretical arguments that the Planck energy (Ep - 10^19
GeV) - should herald departures from Lorentz invariance, and the possibility of
testing these expectations in the not too distant future, two so-called ""Doubly
Special Relativity"" theories have been suggested -- the first by
Amelino-Camelia (DSR1) and the second by Smolin and Magueijo (DSR2). These
theories contain two fundamental scales -- the speed of light and an energy
usually taken to be Ep. The symmetry group is still the Lorentz group, but in
both cases acting nonlinearly on the energy-momentum sector. Accordingly, since
energy and momentum are no longer additive quantities, finding their values for
composite systems (and hence finding the correct conservation laws) is a
nontrivial matter. Ultimately it is these possible deviations from simple
linearly realized relativistic kinematics that provide the most promising
observational signal for empirically testing these models. Various
investigations have narrowed the conservation laws down to two possibilities
per DSR theory. We derive unique exact results for the energy-momentum of
composite systems in both DSR1 and DSR2, and indicate the general strategy for
arbitrary nonlinear realizations of the Lorentz group.",0205067v3
2003-02-02,The conformal metric associated with the U(1) gauge of the Stueckelberg- Schrödinger equation,"We review the classical and quantum mechanics of Stueckelberg, and introduce
the compensation fields necessary for the gauge covariance of the Stueckelberg-
Schr\""odinger equation. To achieve this, one must introduce a fifth, Lorentz
scalar, compensation field, in addition to the four vector fields which
compensate the action of the space-time derivatives. A generalized Lorentz
force can be derived from the classical Hamilton equations associated with this
evolution function. We show that the fifth (scalar) field can be eliminated
through the introduction of a conformal metric on the spacetime manifold. The
geodesic equation associated with this metric coincides with the Lorentz force,
and is therefore dynamically equivalent. Since the generalized Maxwell
equations for the five dimensional fields provide an equation relating the
fifth field with the spacetime density of events, one can derive the spacetime
event density associated with the Friedmann-Robertson-Walker solution of the
Einstein equations. The resulting density, in the conformal coordinate space,
is isotropic and homogeneous, decreasing as the square of the Robertson-Walker
scale factor. Using the Einstein equations, one sees that both for the static
and matter dominated models, the conformal time slice in which the events which
generate the world lines are contained becomes progressively thinner as the
inverse square of the scale factor, establishing a simple correspondence
between the configurations predicted by the underlying
Friedmann-Robertson-Walker dynamical model and the configurations in the
conformal coordinates.",0302001v2
2004-01-06,Whispering Gallery Resonators and Tests of Lorentz Invariance,"The frequencies of a cryogenic sapphire oscillator and a hydrogen maser are
compared to set new constraints on a possible violation of Lorentz invariance.
We give a detailed description of microwave resonators operating in Whispering
Gallery modes and then apply it to derive explicit models for Lorentz violating
effects in our experiment. Models are calculated in the theoretical framework
of Robertson, Mansouri and Sexl and in the standard model extension (SME) of
Kostelecky and co-workers. We constrain the parameters of the Mansouri and Sexl
test theory to $1/2 - \beta_{MS} + \delta_{MS} = (1.2 \pm 2.2) \times 10^{-9}$
and $\beta_{MS} - \alpha_{MS} - 1 = (1.6 \pm 3.0) \times 10^{-7}$ which is of
the same order as the best results from other experiments for the former and
represents a 70 fold improvement for the latter. These results correspond to an
improvement of our previously published limits [Wolf P. et al., Phys. Rev.
Lett. {\bf 90}, 6, 060402, (2003)] by about a factor 2.",0401017v2
2004-07-20,Classical Gravity as an Eikonal Approximation to a Manifestly Lorentz Covariant Quantum Theory with Brownian Interpretation,"We discuss in this Chapter a series of theoretical developments which
motivate the introduction of a quantum evolution equation for which the eikonal
approximation results in the geodesics of a four dimensional manifold. This
geodesic motion can be put into correspondence with general relativity. One
obtains in this way a quantum theory on a flat spacetime, obeying the rules of
the standard quantum theory in Lorentz covariant form, with a spacetime
dependent Lorentz tensor $g_{\mu\nu}$, somewhat analogous to a gauge field,
coupling to the kinetic terms. Since the geodesics predicted by the eikonal
approximation, with appropriate choice of $g_{\mu\nu}$, can be those of general
relativity, this theory provides a quantum theory which could be underlying to
classical gravitation, and coincides with it in this classical ray
approximation. In order to understand the possible origin of the structure of
this equation, we appeal to the approach of Nelson in constructing a
Schroedinger equation from the properties of Brownian motion. Extending the
notion of Browninan motion to spacetime in a covariant way, we show that such
an equation follows from correlations between spacetime dimensions in the
stochastic process.",0407076v1
2005-01-14,Lorentz invariance violation and charge (non--)conservation: A general theoretical frame for extensions of the Maxwell equations,"All quantum gravity approaches lead to small modifications in the standard
laws of physics which lead to violations of Lorentz invariance. One particular
example is the extended standard model (SME). Here, a general phenomenological
approach for extensions of the Maxwell equations is presented which turns out
to be more general than the SME and which covers charge non--conservation
(CNC), too. The new Lorentz invariance violating terms cannot be probed by
optical experiments but need, instead, the exploration of the electromagnetic
field created by a point charge or a magnetic dipole. Some scalar--tensor
theories and higher dimensional brane theories predict CNC in four dimensions
and some models violating Special Relativity have been shown to be connected
with CNC and its relation to the Einstein Equivalence Principle has been
discussed. Due to this upcoming interest, the experimental status of electric
charge conservation is reviewed. Up to now there seem to exist no unique tests
of charge conservation. CNC is related to the precession of polarization, to a
modification of the $1/r$--Coulomb potential, and to a time-dependence of the
fine structure constant. This gives the opportunity to describe a dedicated
search for CNC.",0501048v1
2006-03-09,Signals for Lorentz Violation in Post-Newtonian Gravity,"The pure-gravity sector of the minimal Standard-Model Extension is studied in
the limit of Riemann spacetime. A method is developed to extract the modified
Einstein field equations in the limit of small metric fluctuations about the
Minkowski vacuum, while allowing for the dynamics of the 20 independent
coefficients for Lorentz violation. The linearized effective equations are
solved to obtain the post-newtonian metric. The corresponding post-newtonian
behavior of a perfect fluid is studied and applied to the gravitating many-body
system. Illustrative examples of the methodology are provided using bumblebee
models. The implications of the general theoretical results are studied for a
variety of existing and proposed gravitational experiments, including lunar and
satellite laser ranging, laboratory experiments with gravimeters and torsion
pendula, measurements of the spin precession of orbiting gyroscopes, timing
studies of signals from binary pulsars, and the classic tests involving the
perihelion precession and the time delay of light. For each type of experiment
considered, estimates of the attainable sensitivities are provided. Numerous
effects of local Lorentz violation can be studied in existing or near-future
experiments at sensitivities ranging from parts in 10^4 down to parts in
10^{15}.",0603030v2
1993-04-10,Origin of spontaneous violation of the Lorentz symmetry: Vortices in the cosmos,"By carefully studying the (1,0)+(0,1) representation space for massive
particles we point to the existence of certain inherent tachyonic dispersion
relations: E^2= p^2-m^2. We put forward an interpretation that exploits these
``negative mass squared'' solutions; rotational invariance is spontaneously
broken. Relevance of these results to the vortices in the cosmos is pointed
out.
  NOTE: Just as ""negative energy solutions'' of Dirac equation are
re-interpreted as antiparticles, similarly the possibility exists for
re-interpreting the tachyonic dispersion relations of all (j,0)+(0,j)
representation spaces via spontaneous Lorentz symmetry breaking. In Mod. Phys.
Lett. A8:2623-2630,1993 we exhibited this explicitly for the j=1 representation
space. The interest in this old subject has grown markedly in recent years as
is evident from numerous theoretical and phenomenological works on the subject.
With this observation, we make this replacement of our paper fourteen years
after its initial publication. The Abstract and main text remain unaltered. The
title is changed to reflect the underlying physics more closely.",9304242v2
1998-12-17,"MarKov-Yukawa Transversality On Covariant Null Plane: Pion Form Factor, Gauge Invariance And Lorentz Completion","The Markov-Yukawa Transversality Principle (MYTP) on a 2-body Bethe-Salpeter
kernel is formulated on a covariant Null Plane (NP) to reconstruct the 4D BS
wave function for 2 fermion quarks in terms of 3D entities that satisfy a 3D
BSE. This result is the null-plane counterpart of a 3D-4D interconnection for
the 2-body BS wave functions found earlier by imposing MYTP covariantly in the
instantaneous rest frame (termed CIA) of the composite. This formulation yields
a 3D BSE which is formally identical to its Covariant Instantaneity form, thus
fully preserving its spectral results, while ensuring full covariance. More
importantly, the reconstructed 4D vertex functions in the covariant null-plane
ensure that 4D quark-loops are now free from ill-defined time-like momentum
integrations (which had plagued the earlier CIA vertex functions), while a
simple prescription of `Lorentz completion' in the new description yields a
manifestly Lorentz-invariant result.This is illustrated for the pion and kaon
form factors with full QED gauge-invariance, showing a $k^{-2}$ behaviour at
large $k^2$, and `correct' slopes at small $k^2$. This method is compared with
the Kadychevsky-Karmanov light-front formalism.",9812404v3
2001-04-22,Markov-Yukawa Transversality On Covariant Null-Plane: Baryon Form Factor And Magnetic Moments,"The baryon-$qqq$ vertex function governed by the Markov-Yukawa Transversality
Principle ($MYTP$), is formulated via the Covariant Null-Plane Ansatz ($CNPA$)
as a 3-body generalization of the corresponding $q{\bar q}$ problem, and
employed to calculate the proton e.m. form factor and baryon octet magnetic
moments.The e.m. coupling scheme is specified by letting the e.m. field
interact by turn with the `spectator' while the two interacting quarks fold
back into the baryon. The $S_3$ symmetry of the matrix element is preserved in
all d.o.f.'s together. The $CNPA$ formulation ensures, as in the $q{\bar q}$
case, that the loop integral is free from the Lorentz mismatch disease of
covariant instantaneity ($CIA$), while the simple trick of `Lorentz
completion'ensures a Lorentz invariant structure. The $k^{-4}$ scaling
behaviour at large $k^2$ is reproduced. And with the infrared structure of the
gluonic propagator attuned to spectroscopy, the charge radius of the proton
comes out at $0.96 fm$. The magnetic moments of the baryon octet, also in good
accord with data, are expressible as $(a+b\lambda)/(2+\lambda)$, where $a,b$
are purely geometrical numbers and $\lambda$ a dynamics-dependent quantity.
  PACS: 11.10.St ; 12.90.+b ; 13.40.Fn Key Words : Baryon-$qqq$ Vertex;
Markov-Yukawa Principle (MYTP); 3D-4D Interlinkage; Covariant null-plane
(CNPA); e.m.form factor;baryon magneton.",0104219v1
2001-12-01,The Relativistic Bound State Problem in QCD: Transverse Lattice Methods,"The formalism for describing hadrons using a light-cone Hamiltonian of SU(N)
gauge theory on a coarse transverse lattice is reviewed. Physical gauge degrees
of freedom are represented by disordered flux fields on the links of the
lattice. A renormalised light-cone Hamiltonian is obtained by making a
colour-dielectric expansion for the link-field interactions. Parameters in the
Hamiltonian are renormalised non-perturbatively by seeking regions in parameter
space with enhanced Lorentz symmetry. In the case of pure gauge theories to
lowest non-trivial order of the colour-dielectric expansion, this is sufficient
to determine accurately all parameters in the large-N limit. We summarize
results from applications to glueballs. After quarks are added, the Hamiltonian
and Hilbert space are expanded in both dynamical fermion and link fields.
Lorentz and chiral symmetry are not sufficient to accurately determine all
parameters to lowest non-trivial order of these expansions. However, Lorentz
symmetry and one phenomenological input, a chiral symmetry breaking scale, are
enough to fix all parameters unambiguously. Applications to light-light and
heavy-light mesons are described.",0112007v2
2005-09-28,Testing Lorentz Invariance using Zeeman Transitions in Atomic Fountains,"Lorentz Invariance (LI) is the founding postulate of Einstein's 1905 theory
of relativity, and therefore at the heart of all accepted theories of physics.
It characterizes the invariance of the laws of physics in inertial frames under
changes of velocity or orientation. This central role, and indications from
unification theories hinting toward a possible LI violation, have motivated
tremendous experimental efforts to test LI. A comprehensive theoretical
framework to describe violations of LI has been developed over the last decade:
the Lorentz violating Standard Model Extension (SME). It allows a
characterization of LI violations in all fields of present day physics using a
large (but finite) set of parameters which are all zero when LI is satisfied.
All classical tests (e.g. Michelson-Morley or Kennedy-Thorndike experiments)
can be analyzed in the SME, but it also allows the conception of new types of
experiments, not thought of previously. We have carried out such a conceptually
new LI test, by comparing particular atomic transitions (particular
orientations of the involved nuclear spins) in the $^{133}$Cs atom using a cold
atomic fountain clock. This allows us to test LI in a previously largely
unexplored region of the SME parameter space, corresponding to first
measurements of four proton parameters and an improvement by 11 and 12 orders
of magnitude on the determination of four others. In spite of the attained
accuracies, and of having extended the search into a new region of the SME, we
still find no indication of LI violation.",0509329v2
2005-10-02,"Chiral symmetry restoration in excited hadrons, quantum fluctuations, and quasiclassics","In this paper, we discuss the transition to the semiclassical regime in
excited hadrons, and consequently, the restoration of chiral symmetry for these
states. We use a generalised Nambu-Jona-Lasinio model with the interaction
between quarks in the form of the instantaneous Lorentz-vector confining
potential. This model is known to provide spontaneous breaking of chiral
symmetry in the vacuum via the standard selfenergy loops for valence quarks. It
has been shown recently that the effective single-quark potential is of the
Lorentz-scalar nature, for the low-lying hadrons, while, for the high-lying
states, it becomes a pure Lorentz vector and hence the model exhibits the
restoration of chiral symmetry. We demonstrate explicitly the quantum nature of
chiral symmetry breaking, the absence of chiral symmetry breaking in the
classical limit as well as the transition to the semiclassical regime for
excited states, where the effect of chiral symmetry breaking becomes only a
small correction to the classical contributions.",0510012v3
1993-08-02,On Feynman's Approach to the Foundations of Gauge Theory,"In 1948, Feynman showed Dyson how the Lorentz force and Maxwell equations
could be derived from commutation relations coordinates and velocities. Several
authors noted that the derived equations are not Lorentz covariant and so are
not the standard Maxwell theory. In particular, Hojman and Shepley proved that
the existence of commutation relations is a strong assumption, sufficient to
determine the corresponding action, which for Feynman's derivation is of
Newtonian form. Tanimura generalized Feynman's derivation to a Lorentz
covariant form, however, this derivation does not lead to the standard Maxwell
theory either. Tanimura's force equation depends on a fifth ({\it scalar})
electromagnetic potential, and the invariant evolution parameter cannot be
consistently identified with the proper time of the particle motion. Moreover,
the derivation cannot be made reparameterization invariant; the scalar
potential causes violations of the mass-shell constraint which this invariance
should guarantee. In this paper, we examine Tanimura's derivation in the
framework of the proper time method in relativistic mechanics, and use the
technique of Hojman and Shepley to study the unconstrained commutation
relations. We show that Tanimura's result then corresponds to the
five-dimensional electromagnetic theory previously derived from a
Stueckelberg-type quantum theory in which one gauges the invariant parameter in
the proper time method. This theory provides the final step in Feynman's
program of deriving the Maxwell theory from commutation relations; the Maxwell
theory emerges as the ``correlation limit'' of a more general gauge theory, in
which it is properly contained.",9308003v2
1994-09-19,k-Anomalies and Space-Time Supersymmetry in the Green-Schwarz Heterotic Superstring,"The computation of $\kappa$-anomalies in the Green-Schwarz heterotic
superstring sigma-model and the corresponding Wess-Zumino consistency condition
constitute a powerful alternative approach for the derivation of manifestly
supersymmetric string effective actions. With respect to the beta-function
approach this technique presents the advantage that a result which is obtained
with the computation of beta-functions at $n$ loops can be obtained through the
calculation of $\kappa$-anomalies at \hbox{$n-1$} loops. In this paper we
derive by a direct one-loop perturbative computation the $\kappa$-anomaly
associated to the Yang-Mills Chern-Simons threeform and, for the first time,
the one associated to the Lorentz Chern-Simons threeform. Contrary to what is
often stated in the literature we show that the Lorentz $\kappa$-anomaly gets
contributions from the integration over both the fermionic {\it and\/} bosonic
degrees of freedom of the string. A careful analysis of the absolute
coefficients of all these anomalies reveals that they can be absorbed by
setting $dH={\alpha'\over4}(\trace F^2-\trace R^2)$, where $\alpha'$ is the
string tension, the expected result. We show that this relation ensures also
the absence of gauge and Lorentz anomalies in the sigma-model effective action.
We evidenciate the presence of infrared divergences.",9409107v1
1997-07-21,"Beyond Strings, Multiple Times and Gauge Theories of Area-Scalings Relativistic Transformations","Nottale's special scale-relativity principle was proposed earlier by the
author as a plausible geometrical origin to string theory and extended objects.
Scale Relativity is to scales what motion Relativity is to velocities. The
universal, absolute, impassible, invariant scale under dilatations in Nature is
taken to be the Planck scale, which is not the same as the string scale.
Starting with ordinary actions for strings and other extended objects, we show
that gauge theories of volume-resolutions scale-relativistic symmetries, of the
world volume measure associated with the extended ``fuzzy'' objects, are a
natural and viable way to formulate the geometrical principle underlying the
theory of all extended objects. Gauge invariance can only be implemented if the
extendon actions in $D$ target dimensions are embedded in $D+1$ dimensions with
an extra temporal variable corresponding to the scaling dimension of the
original string coordinates. This is achieved upon viewing the extendon
coordinates, from the fuzzy worldvolume point of view, as noncommuting matrices
valued in the Lie algebra of Lorentz-scale relativistic transformations.
Preliminary steps are taken to merge motion relativity with scale relativity by
introducing the gauge field that gauges the Lorentz-scale symmetries in the
same vain that the spin connection gauges ordinary Lorentz transformations and,
in this fashion, one may go beyond string theory to construct the sought-after
General Theory of Scale-Motion Relativity. Such theory requires the
introduction of the scale-graviton (in addition to the ordinary graviton) which
is the field that gauges the symmetry which converts motion dynamics into
scaling-resolutions dynamics and vice versa (the analog of the gravitino that
gauges supersymmetry). To go beyond the quantum string geometry most probably",9707171v1
1999-04-03,"Tilting the Brane, or Some Cosmological Consequences of the Brane Universe","We discuss theories in which the standard-model particles are localized on a
brane embedded in space-time with large compact extra dimensions, whereas
gravity propagates in the bulk. In addition to the ground state corresponding
to a straight infinite brane, such theories admit a (one parameter) family of
stable configurations corresponding to branes wrapping with certain periodicity
around the extra dimension(s) when one moves along a noncompact coordinate
(tilted walls). In the effective four-dimensional field-theory picture, such
walls are interpreted as one of the (stable) solutions with the constant
gradient energy, discussed earlier. In the cosmological context their energy
""redshifts"" by the Hubble expansion and dissipates slower then the one in
matter or radiation. The tilted wall eventually starts to dominate the
Universe. The upper bound on the energy density coincides with the present
critical energy density. Thus, this mechanism can become significant any time
in the future. The solutions we discuss are characterized by a tiny spontaneous
breaking of both the Lorentz and rotational invariances. Small calculable
Lorentz noninvariant terms in the standard-model Lagrangian are induced. Thus,
the tilted walls provide a framework for the spontaneous breaking of the
Lorentz invariance.",9904021v1
1999-05-12,High energy scattering amplitudes in matrix string theory,"High energy fixed angle scattering is studied in matrix string theory. The
saddle point world sheet configurations, which give the dominant contributions
to the string theory amplitude, are taken as classical backgrounds in matrix
string theory. A one loop fluctuation analysis about the classical background
is performed. An exact treatment of the fermionic and bosonic zero modes is
shown to lead to all of the expected structure of the scattering amplitude. The
ten dimensional Lorentz invariant kinematical structure is obtained from the
fermion zero modes, and the correct factor of the string coupling constant is
obtained from the abelian gauge field zero modes. Up to a numerical factor we
reproduce, from matrix string theory, the high energy limit of the tree level,
four graviton scattering amplitude.",9905087v3
2004-12-05,Rolling Down the Throat in NS5-brane Background: The Case of Electrified D-Brane,"We study rolling radion dynamics of electrified D-brane in NS5-brane
background, both in effective field theory and in full open string theory. We
construct exact boundary states and, from them, extract conserved Noether
currents. We argue that T-duality and Lorentz boost offer an intuitive
approach. In the limit of large number of NS5-branes, both boundary wave
functions and conserved currents are sharply peaked and agree with those
deduced from the effective field theory. As the number of NS5-branes is
reduced, width around the peak becomes wider by string corrections. We also
study radiative decay process. By applying Lorentz covariance, we show how the
decay of electrified D-brane is related to that of bare D-brane. We compute
spectral moments of final state energy and winding quantum number. Using
Lorentz covariance argument, we explain in elementary way why winding quantum
number should be included and derive rules how to do so. We conclude that
Kutasov's ""geometric realization"" between radion rolling dynamics and tachyon
rolling dynamics holds universally, both for bare and electrified D-branes.",0412038v2
2005-03-10,On Interpretation of Special Relativity: a complement to Covariant Harmonic Oscillator Picture,"In 1971 Feynman, Kislinger and Ravndal [1] proposed Lorentz-invariant
differential equation capable to describe relativistic particle with mass and
internal space-time structure. By making use of new variables that
differentiate between space-time particle position and its space-time
separations, one finds this wave equation to become separable and providing the
two kinds of solutions endowed with different physical meanings. The first kind
constitutes the running waves that represent Klein-Gordon-like particle. The
second kind, widely discussed by Kim and Noz [4], constitutes standing waves
which are normalizable space-time wave functions. To fully appreciate how
valuable theses solutions are it seems necessarily, however, to verify a
general outlook on relativity issue that (still) is in force. It was explained
[5] that Lorentz symmetry should be perceived rather as the symmetry of
preferred frame quantum description (based on the freedom of choice of
comparison scale) than classical Galilean idea realized in a generalized form.
Currently we point to some basic consequences that relate to solutions of
Feynman equation framed in the new approach. In particular (i) Lorentz symmetry
group appears to describe energy-dependent geometry of extended quantum objects
instead of relativity of space and time measure, (ii) a new picture of
particle-wave duality involving running and standing waves emerges, (iii)
space-time localized quantum states are shown to provide a new way of
description of particle kinematics, and (iv) proposed by Witten [14]
generalized form of Heisenberg uncertainty relation is derived and shown be the
integral part of overall non-orthodox approach.",0503092v2
2006-03-07,Dirac Monopole from Lorentz Symmetry in N-Dimensions: I. The Generator Extension,"It is by now well-known that a Lorentz force law and the homogeneous Maxwell
equations can be derived from commutation relations among Euclidean coordinates
and velocities, without explicit reference to momentum, action or variational
principle. This result was extended to the relativistic case and shown to
correspond to a Stueckelberg-type quantum theory, in which gauge
transformations may depend on the invariant evolution parameter, such that the
associated the five-dimensional electromagnetism becomes standard Maxwell
theory in the equilibrium limit. Building on the work of Berard, Grandati,
Lages and Mohrbach, we construct an extension of the Lorentz generators in
N-dimensions that restores the closed commutation relations in the presence of
a Maxwell field, and renders the extended generators constants of the classical
motion. The algebra imposes conditions on the Maxwell field, leading to a Dirac
monopole solution. The construction can be maximally satisfied in a three
dimensional subspace of the full Minkowski space; this subspace can be chosen
to describe either the O(3)-invariant space sector, generalizing the
nonrelativistic result, or an O(2,1)-invariant restriction of spacetime, and
leading to a relativistic Coulomb-like potential of the type used by Horwitz
and Arshansky to obtain a covariant generalization of the hydrogen-like bound
state.",0603055v2
2006-07-08,On unique parametrization of the linear group GL(4.C) and its subgroups by using the Dirac matrix algebra basis,"A unifying overview of the ways to parameterize the linear group GL(4.C) and
its subgroups is given. As parameters for this group there are taken 16
coefficients G = G(A,B,A_{k}, B_{k}, F_{kl}) in resolving matrix G in terms of
16 basic elements of the Dirac matrix algebra. Alternatively to the use of 16
tensor quantities, the possibility to parameterize the group GL(4.C) with the
help of four 4-dimensional complex vectors (k, m, n, l) is investigated. The
multiplication rules G'G are formulated in the form of a bilinear function of
two sets of 16 variables. The detailed investigation is restricted to
6-parameter case G(A, B, F_{kl}), which provides us with spinor covering for
the complex orthogonal group SO(3.1.C). The complex Euler's angles
parametrization for the last group is also given. Many different
parametrizations of the group based on the curvilinear coordinates for complex
extension of the 3-space of constant curvature are discussed. The use of the
Newmann-Penrose formalism and applying quaternion techniques in the theory of
complex Lorentz group are considered. Connections between
  Einstein-Mayer study on semi-vectors and Fedorov's treatment of the Lorentz
group theory are stated in detail. Classification of fermions in intrinsic
parities is given on the base of the theory of representations for spinor
covering of the complex Lorentz group.",0607054v1
2007-02-20,Deformed Special Relativity and Deformed Symmetries in a Canonical Framework,"In this paper we have studied the nature of kinematical and dynamical laws in
$\kappa $-Minkowski spacetime from a new perspective: the canonical phase space
approach. We discuss a particular form of $\kappa$-Minkowski phase space
algebra that yields the $\kappa$-extended finite Lorentz transformations
derived in \cite{kim}. This is a particular form of a Deformed Special
Relativity model that admits a modified energy-momentum dispersion law as well
as noncommutative $\kappa$-Minkowski phase space. We show that this system can
be completely mapped to a set of phase space variables that obey canonical (and
{\it{not}} $\kappa$-Minkowski) phase space algebra and Special Relativity
Lorentz transformation (and {\it{not}} $\kappa$-extended Lorentz
transformation). The complete set of deformed symmetry generators are
constructed that obeys an unmodified closed algebra but induce deformations in
the symmetry transformations of the physical $\kappa$-Minkowski phase space
variables. Furthermore, we demonstrate the usefulness and simplicity of this
approach through a number of phenomenological applications both in classical
and quantum mechanics. We also construct a Lagrangian for the
$\kappa$-particle.",0702159v4
2007-03-15,Further results for the two-loop Lcc vertex in the Landau gauge,"In the previous paper hep-th/0604112 we calculated the first of the five
planar two-loop diagrams for the Lcc vertex of the general non-Abelian
Yang-Mills theory, the vertex which allows us in principle to obtain all other
vertices via the Slavnov-Taylor identity. The integrand of this first diagram
has a simple Lorentz structure. In this letter we present the result for the
second diagram, whose integrand has a complicated Lorentz structure. The
calculation is performed in the D-dimensional Euclidean position space. We
initially perform one of the two integrations in the position space and then
reduce the Lorentz structure to D-dimensional scalar single integrals. Some of
the latter are then calculated by the uniqueness method, others by the
Gegenbauer polynomial technique. The result is independent of the ultraviolet
and the infrared scale. It is expressed in terms of the squares of spacetime
intervals between points of the effective fields in the position space -- it
includes simple powers of these intervals, as well as logarithms and
polylogarithms thereof, with some of the latter appearing within the Davydychev
integral J(1,1,1). Concerning the rest of diagrams, we present the result for
the contributions correponding to third, fourth and fifth diagrams without
giving the details of calculation. The full result for the Lcc correlator of
the effective action at the planar two-loop level is written explicitly for
maximally supersymmetric Yang-Mills theory.",0703138v3
1993-11-17,The Fourier transform of order statistics with applications to Lorentz spaces,"We present a formula for the Fourier transforms of order statistics in $\Bbb
R^n$ showing that all these Fourier transforms are equal up to a constant
multiple outside the coordinate planes in $\Bbb R^n.$
  For $a_1\geq ... \geq a_n\ge0$ and $q>0,$ denote by $\ell_{w,q}^n$ the
$n$-dimensional Lorentz space with the norm $\|(x_1,...,x_n)\| = (a_1
(x_1^{*})^q +...+ a_n (x_n^{*})^q)^{1/q}$, where $(x_1^{*},...,x_n^{*})$ is the
non-increasing permutation of the numbers $|x_1|,...,|x_n|.$ We use the above
mentioned formula and the Fourier transform criterion of isometric
embeddability of Banach spaces into $L_q$ \cite{10} to prove that, for $n\geq
3$ and $q\leq 1,$ the space $\ell_{w,q}^n$ is isometric to a subspace of $L_q$
if and only if the numbers $a_1,...,a_n$ form an arithmetic progression. For
$q>1,$ all the numbers $a_i$ must be equal so that $\ell_{w,q}^n = \ell_q^n.$
Consequently, the Lorentz function space $L_{w,q}(0,1)$ is isometric to a
subspace of $L_q$ if and only if {\it either} $0<q<\infty$ and the weight $w$
is a constant function (so that $L_{w,q}= L_q$), {\it or} $q\le 1$ and $w(t)$
is a decreasing linear function.
  Finally, we relate our results to the theory of positive definite functions.",9311208v1
2007-03-12,Schur type inequalities for complex polynomials with no zeros in the unit disk,"Starting out from a question posed by T. Erd\'elyi and J. Szabados, we
consider Schur-type inequalities for the classes of complex algebraic
polynomials having no zeroes within the unit disk D.
  The class of polynomials with no zeroes in D - also known as Bernstein- or
Lorentz-class - was studied in detail earlier. For real polynomials utilizing
the Bernstein-Lorentz representation as convex combinations of fundamental
polynomials (1-x)^k(1+x)^{n-k}, G. Lorentz, T. Erd\'elyi and J. Szabados proved
a number of improved versions of Schur- (and also Bernstein- and Markov-) type
inequalities.
  Here we investigate the similar questions for complex polynomials. For
complex polynomials the above convex representation is not available. Even
worse, the set of complex polynomials, having no zeroes in the unit disk, does
not form a convex set. Therefore, a possible proof must go along different
lines. In fact such a direct argument was asked for by Erd\'elyi and Szabados
already for the real case.
  The sharp forms of the Bernstein- and Markov- type inequalities are known,
and the right factors are worse for complex coefficients than for real ones.
However, here it turns out that Schur-type inequalities hold unchanged even for
complex polynomials and for all monotonic, continuous weight functions. As a
consequence, it becomes possible to deduce the corresponding Markov inequality
from the known Bernstein inequality and the new Schur type inequality with
logarithmic weight.",0703350v1
2005-08-15,The Notions of Distance and Velocity Modulus in the Some Linear Finsler Spaces,"The formulas for the 3-dimensional distance and the velocity modulus in the
4-dimensional linear space with the Berwald-Moor metrics are obtained. The used
algorithm is applicable both for the Minkowski space and for the arbitrary
poly-linear Finsler space in which the time-like component could be chosen. The
constructed here modulus of the 3-dimensional velocity in the space with the
Berwald-Moor metrics coincides with the corresponding expression in the
Galilean space at small (non-relativistic) velocities, while at maximal
velocities, i.e. for the world lines lying on the surface of the cone of
future, this modulus is equal to unity. To construct the 3-dimensional
distance, the notion of the surface of the relative simultaneity is used which
is analogous to the corresponding speculations in special relativity. The
formulas for the velocity transformation when one pass from one inertial frame
to another are obtained. In case when both velocities are directed along one of
the three selected straight lines, the obtained relations coincide with the
analogous relations of special relativity, but they differ in other cases.
Besides, the expressions for the transformations that play the same role as
Lorentz transformations in the Minkowski space are obtained. It was found that
if the three space coordinate axis are straight lines along which the
velocities are added as in special relativity, then taking the velocity of the
new inertial frame collinear to the one of these coordinate axis, one can see
that the transformation of this coordinate and time coordinate coincide with
Lorentz transformations, while the transformations of the two transversal
coordinates differ from the corresponding Lorentz transformations.",0508033v2
1997-02-24,"Space, Time and Superluminal Particles","If textbook Lorentz invariance is actually a property of the equations
describing a sector of matter above some critical distance scale, several
sectors of matter with different critical speeds in vacuum can coexist and an
absolute rest frame (the vacuum rest frame, possibly related to the local rest
frame of the expanding Universe) may exist without contradicting the apparent
Lorentz invariance felt by ""ordinary"" particles (particles with critical speed
in vacuum equal to c , the speed of light). The real geometry of space-time
will then be different from standard Lorentz invariance, and the Poincare
relativity principle will be a local (in space and time), approximate sectorial
property. It seems natural to assume that particles with critical speed in
vacuum different from c are superluminal. We illustrate such a scenario using
as an example a spinorial space-time where the modulus of the spinor,
associated to the time variable, is the size of an expanding Universe. Several
properties of superluminal particles, and of matter without a universal
relativity principle, are discussed in view of experimental applications. If
the vacuum rest frame is close to that suggested by the cosmic microwave
background, experimental searches for superluminal particles on earth should
mainly contemplate a laboratory speed range around 10E3 c , even for very high
energy superluminal cosmic rays. The detectability of several consequences of
the new scenario is briefly discussed.",9702026v1
1997-12-24,Physics Opportunities Above the Greisen-Zatsepin-Kuzmin Cutoff: Lorentz Symmetry Violation at the Planck Scale,"Special relativity has been tested at low energy with great accuracy, but
these results cannot be extrapolated to very high-energy phenomena: this new
domain of physics may actually provide the key to the, yet unsettled, question
of the ether and the absolute rest frame. Introducing a critical distance
scale, a, below 10E-25 cm (the wavelength scale of the highest-energy observed
cosmic rays) allows to consider models, compatible with standard tests of
special relativity, where a small violation of Lorentz symmetry (a can, for
instance, be the Planck length) leads to a deformed relativistic kinematics
(DRK) producing dramatic effects on the properties of very high-energy cosmic
rays. For instance, the Greisen-Zatsepin-Kuzmin (GZK) cutoff does no longer
apply and particles which are unstable at low energy (neutron, some hadronic
resonances like the Delta++, possibly several nuclei...) become stable at very
high energy. In these models, an absolute local rest frame exists (the vacuum
rest frame, VRF) and special relativity is a low-momentum limit. We discuss the
possible effects of Lorentz symmetry violation (LSV) on kinematics and
dynamics, as well as the cosmic-ray energy range (well below the energy scale
associated to the fundamental length) and experiments (on earth and from space)
where they could be detected.",9712047v1
2004-04-25,"Testing Lorentz symmetry of special relativity by means of the Virgo or Ligo set-up, through the differential measure of the two orthogonal beams time-of-flight","A novel experiment to test special relativity via Lorentz symmetry has become
factible thanks to three recent technological achievements: huge Michelson-like
set-up with arms 3 km long (Virgo) and 4 km (Ligo) with beam paths respectively
reaching 120 km and 200 km through multiple reflections, ultrashort laser
pulses of 10-15 s and ultrafast detectors of 10-12 s resolution. The alliance
of these three elements would allow checking the equality of the time-of-flight
of the two orthogonal beams with a resolution high enough to allow prospecting
in a novel way the equivalency of inertial system postulated in special
relativity. In effect, for a beam path length of 120 or 200 km and a net drift
velocity of earth of 370 km/s relative to the cosmic microwave background CMB),
a classical analysis predicts a time-of-flight difference of the order of 10 ns
between the two orthogonal beams, while relativity infers them to be equal. So,
what is under scrutiny is the exhaustivity of the electromagnetic equivalency
of inertial systems. A null time-of-flight difference would strengthen the
Lorentz symmetry, while a non null result would bring a threshold to the
equivalency of inertial systems and at the same time would provide a tool to
define their speed, which should be equal to that relative to the CMB for being
congruent.",0404116v1
2005-06-21,Recent Experimental Tests of Special Relativity,"We review our recent Michelson-Morley (MM) and Kennedy-Thorndike (KT)
experiment, which tests Lorentz invariance in the photon sector, and report
first results of our ongoing atomic clock test of Lorentz invariance in the
matter sector. The MM-KT experiment compares a cryogenic microwave resonator to
a hydrogen maser, and has set the most stringent limit on a number of
parameters in alternative theories to special relativity. We also report first
results of a test of Lorentz invariance in the SME (Standard Model Extension)
matter sector, using Zeeman transitions in a laser cooled Cs atomic fountain
clock. We describe the experiment together with the theoretical model and
analysis. Recent experimental results are presented and we give a first
estimate of components of the $\tilde{c}^p$ parameters of the SME matter
sector. A full analysis of systematic effects is still in progress, and will be
the subject of a future publication together with our final results. If
confirmed, the present limits would correspond to first ever measurements of
some $\tilde{c}^p$ components, and improvements by 11 and 14 orders of
magnitude on others.",0506168v1
2005-12-05,Attempt at clarification of Einstein's postulate of constancy of light velocity,"We have realized that under Lorentz transformations the tick number of a
moving common clock remains unchanged, that is, the hand of the clock never
runs slow, but the time interval between its two consecutive ticks contracts,
so the relative time has to be recorded by using the tau-clocks required by the
transformations, instead of unreal slowing clocks. Thus it is argued that using
rest common clocks or the equivalent the measured velocity of light emitted by
a moving source, which is quasi-velocity of foreign light, is dependent of the
source velocity. Nevertheless, the velocity of foreign light that should be
measured by using tau-clocks is independent of the source velocity. The
velocity of native light emitted by a rest source obeys the postulate of
relativity in accordance with both Maxwell equations and the result of
Michelson-Morley experiment. On the other hand, the velocity of foreign light
obeys both Ritz's emission theory except the Lorentz factor and the postulate
of constancy of light velocity if measured by using tau-clocks. Thus the
emission theory does not conflict with special relativity. The present argument
leads to a logical consequence that the so-called positive conclusions from
experiments testing constancy of the velocity of light emitted by moving
sources if using common clocks or the equivalent, instead of tau-clocks,
exactly contradicts Lorentz transformations.",0512036v2
2006-03-30,Special Relativity in Absolute Space: from a contradiction in terms to an obviousness,"This work deals with the questions of absolute space and relativity. In
particular, an alternative derivation of the effects described by special
relativity is provided, which is based on a description that assumes a
privileged reference frame. The present theory follows the ideas of Lorentz and
Poincare, abandoning a strict view of Einstein's ""equivalence"" of all inertial
frames. The meaning of the Principle of Relativity is discussed and elucidated,
and it is shown that it is not incompatible with the existence of a preferred,
absolute, frame. Most scientists nowadays still consider the basic assumptions
of the theory proposed here to be plain wrong. Moreover, they tend to see an
irreconcilable conflict between the Lorentz-Poincare and the Einstein-Minkowski
formulations. However, as stated by John Bell [Bell1988], although there is a
stringent ""difference in philosophy"" between both views, ""the facts of physics
do not oblige us to accept one philosophy rather than the other"". The validity
of Bell's assertion is unambiguously demonstrated, and it is shown how and why
both approaches do indeed agree in the description of (most of?) the physical
phenomena. Evidently, the physical meaning of the different physical quantities
- such as ""time"", ""speed"", ""simultaneity"" and ""synchronization"" - is quite
different in both programmes. And yet, for perplexing it may look at first
sight, the present theory, developed under the Lorentz-Poincare assumption of a
preferred reference frame, somehow encompasses Einstein's theory. There is no
conflict, as there is one theory. It is stressed that reality is not changed by
the choices one makes to describe it, so it is not changed by the particular
way in which the clocks have been set.",0603258v1
1998-12-02,Generally relativistical Daffin-Kemmer formalis and behaviour of quantm-mechanical particle of spin 1 in the Abelian monopole field,"It is shown that the manner of introducing theinteraction between a spin 1
particle and external classical gravitational field can be successfully uni-
fied with the approach that occurred with regard to a spin 1/2 particle and was
first developed by Tetrode, Weyl, Fock, Ivanenko. On that way a general- ly
relativistical Duffin-Kemmer equation is costructed. So, the manner of
extending the flat space Dirac equation to general relativity case indicates
clearly that the Lorentz group underlies equally both these theories. In other
words, the Lorentz group retains its importance and significance at changing
the Minkowski space model to an arbitrary curved space-time. In contrast to
this, at generalizing the Proca formulation, we automatically destroy any
relations to the Lorentz group, although the definition itself for a spin 1
particle as an elementary object was based on just this group. Such a gravity's
sensitiveness to the fermion-boson division might appear rather strange and
unattractive asymmetry, being subjected to the criticism. Moreover, just this
feature has brought about a plenty of speculation on this matter. In any case,
this peculiarity of particle-gravity field inter- action is recorded almost in
every handbook. In the paper, on the base of the Duffin-Kemmer formalism
developed, the problem of a vector particle in the Abelian monopole potential
is considered.",9812007v1
2002-08-02,Radiation reaction in quantum field theory,"We investigate radiation-reaction effects for a charged scalar particle
accelerated by an external potential realized as a space-dependent mass term in
quantum electrodynamics. In particular, we calculate the position shift of the
final-state wave packet of the charged particle due to radiation at lowest
order in the fine structure constant alpha and in the small h-bar
approximation. We show that it disagrees with the result obtained using the
Lorentz-Dirac formula for the radiation-reaction force, and that it agrees with
the classical theory if one assumes that the particle loses its energy to
radiation at each moment of time according to the Larmor formula in the static
frame of the potential. However, the discrepancy is much smaller than the
Compton wavelength of the particle. We also point out that the electromagnetic
correction to the potential has no classical limit. (Correction. Surface terms
were erroneously discarded to arrive at Eq. (59). By correcting this error we
find that the position shift according to the Lorentz-Dirac theory obtained
from Eq. (12) is reproduced by quantum field theory in the hbar -> 0 limit. We
also find that the small V(z) approximation is unnecessary for this agreement.
See Sec. VII.)",0208017v3
2002-10-28,Physical Interpretation of the Mathematical Consequence of Lorentz' Transformations,"A physical interpretation of the mathematical consequence of Lorentz
transformation within spatial relativity theory is presented as a result of my
new physical model of existent fluctuating vacuum (FlcVcm). It is assumed that
the FlcVcm is considered as a molecular dielectric, which consists from neutral
dynamides, streamlined in a close-packed crystalline lattice. Every dynamide is
a neutral pair, consistent by two massless opposite point-like elementary
electric charges (ElmElcChrgs): electrino (-) and positrino (+). In a frozen
equilibrium position two contrary pont-like ElmElcChrgs within every one
dynamide are very closely installed one to another and therefore the aggregate
polarization of every dynamide and its electric field also have zero values.
The aggregate electric field of every dynamide polarizes nearest neighbors
dynamides in an account of which nearest dynamides interact between them-self,
because of which their elementary excitations, phonons and photons, have a wave
character and behaviors. We suppose that the photon is an polarization result
of the phonon within the fluctuating vacuum considered as an ideal dielectric
and therefore the photon could be considered as an elementary collective
excitation of the FlcVcm in the form of a solitary needle cylindrical harmonic
oscillation. Hence the light, which is a packet of the photons, must move
within FlcVcm with constant velocity and Dopler effect must be observed in both
cases, for the light and sound. Then all mathematical results of Lorentz
transformation could be considered as results of a demand of an independence of
the observation results from the reactive velocity of the observation frame.",0210191v1
2003-02-10,Implications of Lorentz covariance for the guidance equation in two-slit quantum interference,"It is known that Lorentz covariance fixes uniquely the current and the
associated guidance law in the trajectory interpretation of quantum mechanics
for spin particles. In the non-relativistic domain this implies a guidance law
for the electron which differs by an additional spin-dependent term from that
originally proposed by de Broglie and Bohm. In this paper we explore some of
the implications of the modified guidance law. We bring out a property of
mutual dependence in the particle coordinates that arises in product states,
and show that the quantum potential has scalar and vector components which
implies the particle is subject to a Lorentz-like force. The conditions for the
classical limit and the limit of negligible spin are given, and the empirical
sufficiency of the model is demonstrated. We then present a series of
calculations of the trajectories based on two-dimensional Gaussian wave packets
which illustrate how the additional spin-dependent term plays a significant
role in structuring both the individual trajectories and the ensemble. The
single packet corresponds to quantum inertial motion. The distinct features
encountered when the wavefunction is a product or a superposition are explored,
and the trajectories that model the two-slit experiment are given. The latter
paths exhibit several new characteristics compared with the original de
Broglie-Bohm ones, such as crossing of the axis of symmetry.",0302076v1
2005-02-15,"Coupled oscillators, entangled oscillators, and Lorentz-covariant harmonic oscillators","Other than scattering problems where perturbation theory is applicable, there
are basically two ways to solve problems in physics. One is to reduce the
problem to harmonic oscillators, and the other is to formulate the problem in
terms of two-by-two matrices. If two oscillators are coupled, the problem
combines both two-by-two matrices and harmonic oscillators. This method then
becomes a powerful research tool to cover many different branches of physics.
Indeed, the concept and methodology in one branch of physics can be translated
into another through the common mathematical formalism. Coupled oscillators
provide clear illustrative examples for some of the current issues in physics,
including entanglement and Feynman's rest of the universe. In addition, it is
noted that the present form of quantum mechanics is largely a physics of
harmonic oscillators. Special relativity is the physics of the Lorentz group
which can be represented by the group of two-by-two matrices commonly called
$SL(2,c)$. Thus the coupled harmonic oscillators can play the role of combining
quantum mechanics with special relativity. It is therefore possible to relate
the current issues of physics to the Lorentz-covariant formulation of quantum
mechanics.",0502096v3
2007-05-14,Bigravity and Lorentz-violating Massive Gravity,"Bigravity is a natural arena where a non-linear theory of massive gravity can
be formulated. If the interaction between the metrics $f$ and $g$ is
non-derivative, spherically symmetric exact solutions can be found. At large
distances from the origin, these are generically Lorentz-breaking bi-flat
solutions (provided that the corresponding vacuum energies are adjusted
appropriately). The spectrum of linearized perturbations around such
backgrounds contains a massless as well as a massive graviton, with {\em two}
physical polarizations each. There are no propagating vectors or scalars, and
the theory is ghost free (as happens with certain massive gravities with
explicit breaking of Lorentz invariance). At the linearized level, corrections
to GR are proportional to the square of the graviton mass, and so there is no
vDVZ discontinuity. Surprisingly, the solution of linear theory for a static
spherically symmetric source does {\em not} agree with the linearization of any
of the known exact solutions. The latter coincide with the standard
Schwarzschild-(A)dS solutions of General Relativity, with no corrections at
all. Another interesting class of solutions is obtained where $f$ and $g$ are
proportional to each other. The case of bi-de Sitter solutions is analyzed in
some detail.",0705.1982v4
2007-07-14,General Very Special Relativity is Finsler Geometry,"We ask whether Cohen and Glashow's Very Special Relativity model for Lorentz
violation might be modified, perhaps by quantum corrections, possibly producing
a curved spacetime with a cosmological constant. We show that its symmetry
group ISIM(2) does admit a 2-parameter family of continuous deformations, but
none of these give rise to non-commutative translations analogous to those of
the de Sitter deformation of the Poincar\'e group: spacetime remains flat. Only
a 1-parameter family DISIM_b(2) of deformations of SIM(2) is physically
acceptable. Since this could arise through quantum corrections, its
implications for tests of Lorentz violations via the Cohen-Glashow proposal
should be taken into account. The Lorentz-violating point particle action
invariant under DISIM_b(2) is of Finsler type, for which the line element is
homogeneous of degree 1 in displacements, but anisotropic. We derive
DISIM_b(2)-invariant wave equations for particles of spins 0, 1/2 and 1. The
experimental bound, $|b|<10^{-26}$, raises the question ``Why is the
dimensionless constant $b$ so small in Very Special Relativity?''",0707.2174v2
2007-09-24,Some Impacts of Lorentz Violation on Cosmology,"The impact of Lorentz violation on the dynamics of a scalar field is
investigated. In particular, we study the dynamics of a scalar field in the
scalar-vector-tensor theory where the vector field is constrained to be unity
and time like. By taking a generic form of the scalar field action, a
generalized dynamical equation for the scalar-vector-tensor theory of gravity
is obtained to describe the cosmological solutions. We present a class of exact
solutions for an ordinary scalar field or phantom field corresponding to a
power law coupling vector and the Hubble parameter. As the results, we find a
constant equation of state in de Sitter space-time and power law expansion with
the quadratic of coupling vector, while a dynamic equation of state is obtained
for $n> 2$. Then, we consider the inflationary scenario based on the Lorentz
violating scalar-vector-tensor theory of gravity with general power-law
coupling vector and two typical potentials: inverse power-law and power-law
potentials. In fact, both the coupling vector and the potential models affect
the dynamics of the inflationary solutions. Finally, we use the dynamical
system formalism to study the attractor behavior of a cosmological model
containing a scalar field endowed with a quadratic coupling vector and a
chaotic potential.",0709.3688v2
2007-09-28,Gamma-Ray Burst high energy emission from Internal Shocks,"In this paper we study synchrotron and synchrotron self Compton (SSC)
emission from internal shocks (IS) during the prompt and X-ray flare phases of
Gamma-Ray Bursts (GRBs). The aim is to test the IS model for the flare emission
and for whether GRBs can be GeV sources. We determine the parameters for which
the IS model can account for the observed prompt and X-ray flares emission, and
study the detectability of the high energy SSC emission by the AGILE and GLAST
satellites. We find that the detectability of the SSC emission during the
prompt phase of GRBs improves for higher values of the fireball Lorentz factor
and of the temporal variability. If IS is the mechanism responsible of the
flare emission, and the Lorentz factor of the shells producing the flare is of
the order of 100, the flare light curves are expected to present some
substructures with temporal variability of 10-100 ms which are much smaller
than the average duration of flares, and similar to those observed during the
prompt phase of GRBs. If one assumes lower Lorentz factors, such as 10-25, then
a larger temporal variaibility of 40 s can also account for the observed flare
properties. However in this case we predict that X-ray flares do not have a
counterpart at very high energies (MeV-GeV). An investigation on the
substructures of the X-ray flares light curves, and simultaneous X-ray and high
energy observations, will allow us to corroborate the hypothesis that late IS
are responsible of the X-ray flares.",0709.4568v2
2007-11-21,The Structure of E6,"We present the subalgebra structure of sl(3,O), a particular real form of E6
chosen for its relevance to particle physics through the connection between its
associated Lie group SL(3,O) and generalized Lorentz groups. Given the
complications related to the non-associativity of the octonions O and the
restriction to working with a real form of E6, we find that the traditional
methods used to study Lie algebras must be modified for our purposes. We use an
explicit representation of the Lie group SL(3,O) to produce the multiplication
table of the corresponding algebra sl(3,O). Both the multiplication table and
the group are then utilized to find subalgebras of sl(3,O). In particular, we
identify various subalgebras of the form sl(n, F) and su(n, F) within sl(3,O)
and we also find algebras corresponding to generalized Lorentz groups. Methods
based upon automorphisms of complex Lie algebras are developed to find less
obvious subalgebras of sl(3,O). While we focus on the subalgebra structure of
our real form of E6, these methods may also be used to study the subalgebra
structure of any other real form of E6. A maximal set of simultaneously
measurable observables in physics corresponds to a maximal set of Casimir
operators in the Lie algebra. We not only identify six Casimir operators in E6,
but produce a nested sequence of subalgebras and Casimir operators in E6
containing both su(3)+su(2)+u(1) corresponding to the Standard Model and the
Lorentz group of special relativity.",0711.3447v2
2007-12-04,"Analogue spacetimes: Toy models for ""quantum gravity''","Why are ""analogue spacetimes'' interesting? For the purposes of this workshop
the answer is simple: Analogue spacetimes provide one with physically
well-defined and physically well-understood concrete models of many of the
phenomena that seem to be part of the yet incomplete theory of ""quantum
gravity'', or more accessibly, ""quantum gravity phenomenology''. Indeed
""analogue spacetimes'' provide one with concrete models of ""emergence''
(whereby the effective low-energy theory can be radically different from the
high-energy microphysics). They also provide many concrete and controlled
models of ""Lorentz symmetry breaking'', and extensions of the usual notions of
pseudo-Riemannian geometry such as ""rainbow spacetimes'', and pseudo-Finsler
geometries, and more. I will provide an overview of the key items of ""unusual
physics'' that arise in analogue spacetimes, and argue that they provide us
with hints of what we should be looking for in any putative theory of ""quantum
gravity''. For example: The dispersion relations that naturally arise in the
known emergent/analogue spacetimes typically violate analogue Lorentz
invariance at high energy, but do not do so in completely arbitrary manner.
This suggests that a search for arbitrary violations of Lorentz invariance is
possibly overkill: There are a number of natural and physically well-motivated
restrictions one can put on emergent/ analogue dispersion relations,
considerably reducing the plausible parameter space.",0712.0427v1
2007-12-26,"Spontaneous Lorentz and Diffeomorphism Violation, Massive Modes, and Gravity","Theories with spontaneous local Lorentz and diffeomorphism violation contain
massless Nambu-Goldstone modes, which arise as field excitations in the minimum
of the symmetry-breaking potential. If the shape of the potential also allows
excitations above the minimum, then an alternative gravitational Higgs
mechanism can occur in which massive modes involving the metric appear. The
origin and basic properties of the massive modes are addressed in the general
context involving an arbitrary tensor vacuum value. Special attention is given
to the case of bumblebee models, which are gravitationally coupled vector
theories with spontaneous local Lorentz and diffeomorphism violation. Mode
expansions are presented in both local and spacetime frames, revealing the
Nambu-Goldstone and massive modes via decomposition of the metric and bumblebee
fields, and the associated symmetry properties and gauge fixing are discussed.
The class of bumblebee models with kinetic terms of the Maxwell form is used as
a focus for more detailed study. The nature of the associated conservation laws
and the interpretation as a candidate alternative to Einstein-Maxwell theory
are investigated. Explicit examples involving smooth and Lagrange-multiplier
potentials are studied to illustrate features of the massive modes, including
their origin, nature, dispersion laws, and effects on gravitational
interactions. In the weak static limit, the massive mode and
Lagrange-multiplier fields are found to modify the Newton and Coulomb
potentials. The nature and implications of these modifications are examined.",0712.4119v2
2008-01-15,A modification of Einstein-Schrodinger theory that contains both general relativity and electrodynamics,"We modify the Einstein-Schrodinger theory to include a cosmological constant
$\Lambda_z$ which multiplies the symmetric metric, and we show how the theory
can be easily coupled to additional fields. The cosmological constant
$\Lambda_z$ is assumed to be nearly cancelled by Schrodinger's cosmological
constant $\Lambda_b$ which multiplies the nonsymmetric fundamental tensor, such
that the total $\Lambda=\Lambda_z+\Lambda_b$ matches measurement. The resulting
theory becomes exactly Einstein-Maxwell theory in the limit as
$|\Lambda_z|\to\infty$. For $|\Lambda_z|\sim 1/(Planck length)^2$ the field
equations match the ordinary Einstein and Maxwell equations except for extra
terms which are $<10^{-16}$ of the usual terms for worst-case field strengths
and rates-of-change accessible to measurement. Additional fields can be
included in the Lagrangian, and these fields may couple to the symmetric metric
and the electromagnetic vector potential, just as in Einstein-Maxwell theory.
The ordinary Lorentz force equation is obtained by taking the divergence of the
Einstein equations when sources are included. The Einstein-Infeld-Hoffmann
(EIH) equations of motion match the equations of motion for Einstein-Maxwell
theory to Newtonian/Coulombian order, which proves the existence of a Lorentz
force without requiring sources. This fixes a problem of the original
Einstein-Schrodinger theory, which failed to predict a Lorentz force. An exact
charged solution matches the Reissner-Nordstrom solution except for additional
terms which are $\sim 10^{-66}$ of the usual terms for worst-case radii
accessible to measurement. An exact electromagnetic plane-wave solution is
identical to its counterpart in Einstein-Maxwell theory.",0801.2307v2
2008-03-22,Lorentz Transformation and General Covariance Principle,"I tell about different mathematical tool that is important in general
relativity. The text of the book includes definition of geometrical object,
concept of reference frame, geometry of metric-affinne manifold. Using this
concept I learn few physical applications: dynamics and Lorentz transformation
in gravitational fields, Doppler shift.
  A reference frame in event space is a smooth field of orthonormal bases.
Every reference frame is equipped by anholonomic coordinates. Using anholonomic
coordinates allows to find out relative speed of two observers and appropriate
Lorentz transformation. Synchronization of a reference frame is an anholonomic
time coordinate. Simple calculations show how synchronization influences time
measurement in the vicinity of the Earth. Measurement of Doppler shift from the
star orbiting the black hole helps to determine mass of the black hole.
  We call a manifold with torsion and nonmetricity the metric\hyph affine
manifold. The nonmetricity leads to a difference between the auto parallel line
and the extreme line, and to a change in the expression of the Frenet transport
and moving basis. The torsion leads to a change in the Killing equation. We
also need to add a similar equation for the connection.
  The analysis of the Frenet transport leads to the concept of the Cartan
transport and an introduction of the connection compatible with the metric
tensor. The dynamics of a particle follows to the Cartan transport. We need
additional physical constraints to make a nonmetricity observable. Learning how
torsion influences on tidal force reveals similarity between tidal equation for
geodesic and the Killing equation of second type.",0803.3276v4
2008-06-02,Gamma-ray emission of relativistic jets as a supercritical process,"Supercriticality of the same kind as that in a nuclear pile can take place in
high-energy astrophysical objects producing a number of impressive effects. For
example, it could cause an explosive release of the energy of a cloud of
ultrarelativistic protons into radiation. More certainly, supercriticality
should be responsible for energy dissipation of very energetic relativistic
fluids such as ultrarelativistic shocks in gamma-ray bursts and jets in active
galactic nuclei (AGNs). In this case, the photon breeding process operates. It
is a kind of the converter mechanism with the high-energy photons and e^+ e^-
pairs converting into each other via pair production and inverse Compton
scattering. Under certain conditions, which should be satisfied in powerful
AGNs, the photon breeding mechanism becomes supercritical: the high-energy
photons breed exponentially until their feedback on the fluid changes its
velocity pattern. Then the system comes to a self-adjusting near-critical
steady state. Monte-Carlo simulations with the detailed treatment of particle
propagation and interactions demonstrate that a jet with the Lorentz factor
Gamma ~ 20 can radiate away up to a half of its total energy and for Gamma=40
the radiation efficiency can be up to 80 per cent. Outer layers of the jet
decelerate down to a moderate Lorentz factor 2-4, while the spine of the jet
has the final Lorentz factor in the range 10-20 independently on the initial
Gamma. Such sharp deceleration under the impact of radiation must cause a
number of interesting phenomena such as formation of internal shocks and an
early generation of turbulence.",0806.0323v1
2008-11-10,Magnetic acceleration of ultra-relativistic jets in gamma-ray burst sources,"We present a relativistic-MHD numerical study of axisymmetric, magnetically
driven jets with parameters applicable to gamma-ray burst (GRB) flows. We also
present analytic expressions for the asymptotic jet shape and other flow
parameters that agree very well with the numerical results. All
current-carrying outflows exhibit self-collimation and consequent acceleration
near the rotation axis, but unconfined outflows lose causal connectivity across
the jet and therefore do not collimate or accelerate efficiently in their outer
regions. Magnetically accelerated jets confined by an external pressure that
varies with distance with a power-law index < 2 assume a paraboloidal shape and
have an acceleration efficiency > 50%. They attain Lorentz factors > 30 on
scales 10^9-3x10^10 cm, consistent with the possibility that short/hard GRB
jets are accelerated on scales where they can be confined by moderately
relativistic winds from accretion discs, and > 100 on scales 10^10-10^12 cm,
consistent with the possibility that long/soft GRB jets are accelerated within
the envelopes of collapsing massive stars. We also find that the Lorentz factor
of a magnetically accelerated jet is approximately inversely proportional to
the opening half-angle of the poloidal streamlines. This implies that the
gamma-ray emitting components of GRB outflows are very narrow, with a
half-angle < 1 degree in regions where the Lorentz factor exceeds 100, and that
the afterglow light curves of these components would either exhibit a very
early jet break or show no jet break at all.",0811.1467v2
2008-11-13,Lorentz Invariance Violation and the Observed Spectrum of Ultrahigh Energy Cosmic Rays,"There has been much interest in possible violations of Lorentz invariance,
particularly motivated by quantum gravity theories. It has been suggested that
a small amount of Lorentz invariance violation (LIV) could turn off photomeson
interactions of ultrahigh energy cosmic rays (UHECRs) with photons of the
cosmic background radiation and thereby eliminate the resulting sharp
steepening in the spectrum of the highest energy CRs predicted by Greisen
Zatsepin and Kuzmin (GZK). Recent measurements of the UHECR spectrum reported
by the HiRes and Auger collaborations, however, indicate the presence of the
GZK effect. We present the results of a detailed calculation of the
modification of the UHECR spectrum caused by LIV using the formalism of Coleman
and Glashow. We then compare these results with the experimental UHECR data
from Auger and HiRes. Based on these data, we find a best fit amount of LIV of
$4.5^{+1.5}_{-4.5} \times 10^{-23}$,consistent with an upper limit of $6 \times
10^{-23}$. This possible amount of LIV can lead to a recovery of the cosmic ray
spectrum at higher energies than presently observed. Such an LIV recovery
effect can be tested observationally using future detectors.",0811.2230v4
2009-01-10,Testing symmetries in effective models of higher derivative field theories,"Higher derivative field theories with interactions raise serious doubts about
their validity due to severe energy instabilities. In many cases the
implementation of a direct perturbation treatment to excise the dangerous
negative-energies from a higher derivative field theory may lead to violations
of Lorentz and other symmetries. In this work we study a perturbative
formulation for higher derivative field theories that allows the construction
of a low-energy effective field theory being a genuine perturbations over the
ordinary-derivative theory and having a positive-defined Hamiltonian. We show
that some discrete symmetries are recovered in the low-energy effective theory
when the perturbative method to reduce the negative-energy degrees of freedom
from the higher derivative theory is applied. In particular, we focus on the
higher derivative Maxwell-Chern-Simons model which is a Lorentz invariant and
parity-odd theory in 2+1 dimensions. The parity violation arises in the
effective action of QED$_3$ as a quantum correction from the massive fermionic
sector. We obtain the effective field theory which remains Lorentz invariant,
but parity invariant to the order considered in the perturbative expansion.",0901.1341v2
2009-01-27,"The Dirac equation and a non-chiral electroweak theory in six dimensional spacetime from a locally gauged SO(3,3) symmetry group","A toy model for the electroweak interactions(without chirality) is proposed
in a six dimensional spacetime with 3 timelike and 3 spacelike coordinates. The
spacetime interval $ds^2=dx_\mu dx^\mu$ is left invariant under the symmetry
group SO(3,3). We obtain the six-dimensional version of the Dirac gamma
matrices, $\Gamma_\mu$, and write down a Dirac-like lagrangian density, ${\cal
L}=i \bar{\psi} \Gamma ^\mu \nabla_\mu \psi$. The spinor $\psi$ is decomposed
into two Dirac spinors, $\psi_1$ and $\psi_2$, which we interpret as the
electron and neutrino fields, respectively. In six-dimensional spacetime the
electron and neutrino fields are then merged in a natural manner. The SO(3,3)
Lorentz symmetry group must be locally broken to the observable SO(1,3) Lorentz
group, with only one observable time component, $t_z$. The $t_z$-axis may not
be the same at all points of the spacetime and the effect of breaking the
SO(3,3) spacetime symmetry group locally to an SO(1,3) Lorentz group is
perceived by the observers as the existence of the gauge fields. The origin of
mass may be attributed to the remaining two hidden timelike dimensions. We
interpret the origin of mass and gauge interactions as a consequence of extra
time dimensions, without the need of the so-called Higgs mechanism for the
generation of mass. Further, we are able to give a geometric meaning to the
electromagnetic and non-abelian gauge symmetries.",0901.4230v1
2009-02-10,Planck-scale Lorentz violation constrained by Ultra-High-Energy Cosmic Rays,"We investigate the consequences of higher dimension Lorentz violating, CPT
even kinetic operators that couple standard model fields to a non-zero vector
field in an Effective Field Theory framework. Comparing the ultra-high energy
cosmic ray spectrum reconstructed in the presence of such terms with data from
the Pierre Auger observatory allows us to establish two sided bounds on the
coefficients of the mass dimension five and six operators for the proton and
pion. Our bounds imply that for both protons and pions, the energy scale of
Lorentz symmetry breaking must be well above the Planck scale. In particular,
the dimension five operators are constrained at the level of $10^{-3} M_{\rm
Planck}^{-1}$. The magnitude of the dimension six proton coefficient is bounded
at the level of $10^{-6} M_{Planck}^{-2}$ except in a narrow range where the
pion and proton coefficients are both negative and nearly equal. In this small
area, the magnitude of the dimension six proton coefficient must only be below
$10^{-3} M_{\rm Planck}^{-2}$. Constraints on the dimension six pion
coefficient are found to be much weaker, but still below $M_{\rm Planck}^{-2}$.",0902.1756v3
2009-03-27,On the Gamma Ray Burst Origin of Extremely Energetic Cosmic Rays,"Air shower experiments have detected cosmic ray events of energies upto 300
EeV. Most likely these cosmic rays have originated from compact objects. Their
exact sources are yet to be identified. It has been suggested before that gamma
ray bursts are possible sources of ultra-high energy cosmic rays. The two
models of gamma ray burst emissions most often discussed are the internal and
external shock models. We have calculated the proton spectrum above 60EeV from
all gamma ray bursts distributed upto a redshift of 0.02 in the internal shock
model assuming redshift and luminosity distributions consistent with
observations, log normal distributions for their values of Lorentz factors,
variability times and duration of bursts. Within the external shock model we
have calculated the proton flux above 60EeV from all nearby gamma ray bursts
assuming log normal distributions in their values of total energies, Lorentz
factors at the deceleration epoch and compared with the observed data. We find
that gamma ray bursts can produce cosmic ray proton flux comparable to the flux
observed by the Pierre Auger experiment both within the internal and external
shock models. We have also studied the dependence of the maximum proton
energies and the cooling breaks in the proton spectrum on the various
parameters like Lorentz factor, energy of the GRB fireball, variability time
(in case of internal shocks), ambient particle density (in case of external
shocks). Our results are important to understand how the various observable
parameters determine which mechanism e.g. $p\gamma$ interactions, synchrotron
cooling of protons will dominate over one another inside these sources.",0903.4733v1
2009-05-11,Lorentz Breaking Massive Gravity in Curved Space,"A systematic study of the different phases of Lorentz-breaking massive
gravity in a curved background is performed. For tensor and vector modes, the
analysis is very close to that of Minkowski space. The most interesting results
are in the scalar sector where, generically, there are two propagating degrees
of freedom (DOF). While in maximally symmetric spaces ghost-like instabilities
are inevitable, they can be avoided in a FRW background. The phases with less
than two DOF in the scalar sector are also studied. Curvature allows an
interesting interplay with the mass parameters; in particular, we have extended
the Higuchi bound of dS to FRW and Lorentz breaking masses. As in dS, when the
bound is saturated there is no propagating DOF in the scalar sector. In a
number of phases the smallness of the kinetic terms gives rise to strongly
coupled scalar modes at low energies. Finally, we have computed the
gravitational potentials for point-like sources. In the general case we recover
the GR predictions at small distances, whereas the modifications appear at
distances of the order of the characteristic mass scale. In contrast with
Minkowski space, these corrections may not spoil the linear approximation at
large distances.",0905.1699v1
2009-05-13,Fiber averaged dynamics associated with the Lorentz force equation,"It is shown that the Lorentz force equation is equivalent to the
auto-parallel condition $\,^L\nabla_{\dot{{x}}}\dot{{x}}=0$ of a linear
connection $^L\nabla$ defined on a convenient pull-back vector bundle. By using
a geometric averaging method, an associated {\it averaged Lorentz connection}
$\langle\,^L\nabla\rangle$ and the corresponding auto-parallel equation are
obtained. After this, it is shown that in the ultra-relativistic limit and for
narrow one-particle probability distribution functions, the auto-parallel
curves of $\langle\,^L\nabla\rangle$ remain {\it nearby} close to the
auto-parallel curves of $^L\nabla$. Applications of this result in beam
dynamics and plasma physics are briefly described.",0905.2060v12
2009-08-12,"Massive neutrinos, Lorentz invariance dominated standard model and the phenomenological approach to neutrino oscillations","For the electroweak interactions, the massive neutrino perturbative
kinematical procedure is developed in the massive neutrino Fock space. This
yields the dominant Lorentz invariant Standard Model mass-less flavor neutrino
cross-sections as well as the neutrino oscillation cross-sections some of which
are Lorentz invariance and flavor conservation violating. But all these
oscillating cross-sections being proportional to the squares of neutrino masses
are practically unobservable in the laboratory; however, they are consistent
with the original Pontecorvo neutrino oscillating transition probability
expression at short time (baseline), as presented by Dvornikov. Then, by
mimicking the time dependence of the original Pontecorvo neutrino oscillating
transition probability, one can formulate the dimensionless neutrino
intensity-probability I, by phenomenological extrapolating the time t, or,
equivalently the baseline distance L away from the collision point for the
oscillating differential cross-section. For the incoming neutrino of 10MeV in
energy and neutrino masses from Fritzsch analysis with the neutrino mixing
matrix of Harrison, Perkins and Scott, the baseline distances at the first two
maxima of the neutrino intensity are L=281km and L=9279km . The intensity I at
the first maximum conserves the flavor, while at the second maximum; the
intensities violate the flavor, respectively, in the final and initial state.
At the end some details are given as to how these neutrino oscillations away
from the collision point one should be able to verify experimentally.",0908.1763v2
2009-09-08,Feynman and Squeezed States,"In 1971, Feynman et al. published a paper on hadronic mass spectra and
transition rates based on the quark model. Their starting point was a
Lorentz-invariant differential equation. This equation can be separated into a
Klein-Gordon equation for the free-moving hadron and a harmonic oscillator
equation for the quarks inside the hadron. However, their solution of the
oscillator equation is not consistent with the existing rules of quantum
mechanics and special relativity. On the other hand, their partial differential
equation has many other solutions depending on boundary conditions. It is noted
that there is a Lorentz-covariant set of solutions totally consistent with
quantum mechanics and special relativity. This set constitutes a representation
of the Poincar\'e group which dictates the fundamental space-time symmetry of
particles in the Lorentz-covariant world. It is then shown that the same set of
solutions can be used as the mathematical basis for two-photon coherent states
or squeezed states in quantum optics. It is thus possible to transmit the
physics of squeezed states into the hadronic world. While the time-like
separation is the most puzzling problem in the covariant oscillator regime,
this variable can be interpreted like the unobserved photon in the two-mode
squeezed state which leads to an entropy increase.",0909.1578v1
2009-09-28,An Analytical Model Probing the Internal State of Coronal Mass Ejections Based on Observations of Their Expansions and Propagations,"In this paper, a generic self-similar flux rope model is proposed to probe
the internal state of CMEs in order to understand the thermodynamic process and
expansion of CMEs in interplanetary space. Using this model, three physical
parameters and their variations with heliocentric distance can be inferred
based on coronagraph observations of CMEs' propagation and expansion. One is
the polytropic index $\Gamma$ of the CME plasma, and the other two are the
average Lorentz force and the thermal pressure force inside CMEs. By applying
the model to the 2007 October 8 CME observed by STEREO/SECCHI, we find that (1)
the polytropic index of the CME plasma increased from initially 1.24 to more
than 1.35 quickly, and then slowly decreased to about 1.34; it suggests that
there be continuously heat injected/converted into the CME plasma and the value
of $\Gamma$ tends to be 4/3, a critical value inferred from the model for a
force-free flux rope; (2) the Lorentz force directed inward while the thermal
pressure force outward, and both of them decreased rapidly as the CME moved
out; the direction of the two forces reveals that the thermal pressure force is
the internal driver of the CME expansion whereas the Lorentz force prevented
the CME from expanding. Some limitations of the model and approximations are
discussed meanwhile.",0909.5060v1
2009-10-16,Deforming the Maxwell-Sim Algebra,"The Maxwell alegbra is a non-central extension of the Poincar\'e algebra, in
which the momentum generators no longer commute, but satisfy
$[P_\mu,P_\nu]=Z_{\mu\nu}$. The charges $Z_{\mu\nu}$ commute with the momenta,
and transform tensorially under the action of the angular momentum generators.
If one constructs an action for a massive particle, invariant under these
symmetries, one finds that it satisfies the equations of motion of a charged
particle interacting with a constant electromagnetic field via the Lorentz
force. In this paper, we explore the analogous constructions where one starts
instead with the ISim subalgebra of Poincar\'e, this being the symmetry algebra
of Very Special Relativity. It admits an analogous non-central extension, and
we find that a particle action invariant under this Maxwell-Sim algebra again
describes a particle subject to the ordinary Lorentz force. One can also deform
the ISim algebra to DISim$_b$, where $b$ is a non-trivial dimensionless
parameter. We find that the motion described by an action invariant under the
corresponding Maxwell-DISim algebra is that of a particle interacting via a
Finslerian modification of the Lorentz force.",0910.3220v2
2009-10-28,Resolving Puzzles of Massive Gravity with and without violation of Lorentz symmetry,"We perform a systematic study of various versions of massive gravity with and
without violation of Lorentz symmetry in arbitrary dimension. These theories
are well known to possess very unusual properties, unfamiliar from studies of
gauge and Lorentz invariant models. These peculiarities are caused by mixing of
familiar transverse fields with revived longitudinal and pure gauge
(Stueckelberg) fields and are all seen already in quadratic approximation. They
are all associated with non-trivial dispersion laws, which easily allow
superluminal propagation, ghosts, tachyons and essential irrationalities.
Moreover, coefficients in front of emerging modes are small, what makes the
theories essentially non-perturbative within a large Vainshtein radius.
Attempts to get rid of unwanted degrees of freedom by giving them infinite
masses lead to DVZ discontinuities in parameter (moduli) space, caused by
un-permutability of different limits. Also, the condition m_{gh}=\infty can not
be preserved already in non-trivial gravitational backgrounds and is unstable
under any other perturbations of linearized gravity. At the same time an {\it a
priori} healthy model of massive gravity in quadratic approximation definitely
exists: provided by any mass level of Kaluza-Klein tower. It bypasses the
problems because gravity field is mixed with other fields, and this explains
why such mixing helps in other models. At the same time this can imply that the
really healthy massive gravity can still require infinite number of extra
fields beyond quadratic approximation.",0910.5243v1
2009-11-03,Possible cosmogenic neutrino constraints on Planck-scale Lorentz violation,"We study, within an effective field theory framework, $O(E^{2}/\Mpl^{2})$
Planck-scale suppressed Lorentz invariance violation (LV) effects in the
neutrino sector, whose size we parameterize by a dimensionless parameter
$\eta_{\nu}$. We find deviations from predictions of Lorentz invariant physics
in the cosmogenic neutrino spectrum. For positive O(1) coefficients no neutrino
will survive above $10^{19} \eV$. The existence of this cutoff generates a bump
in the neutrino spectrum at energies of $10^{17} \eV$. Although at present no
constraint can be cast, as current experiments do not have enough sensitivity
to detect ultra-high-energy neutrinos, we show that experiments in construction
or being planned have the potential to cast limits as strong as $\eta_{\nu}
\lesssim 10^{-4}$ on the neutrino LV parameter, depending on how LV is
distributed among neutrino mass states. Constraints on $\eta_{\nu} < 0$ can in
principle be obtained with this strategy, but they require a more detailed
modeling of how LV affects the neutrino sector.",0911.0521v2
2010-01-18,Beyond the Fundamentals of Special Relativity: Full Lorentz gamma factor,"Special relativity calculates, by means of the Lorentz gamma factor, the
proper time of all inertial systems from the observer proper time, which is
taken as a time standard. So, any temporal inference relies in first instance
on the observer own time. The question is thus: what fixes the observer proper
time? This will be the crucial point debated here. This implies analyzing at
the very first why the observer can be taken as a motionless reference in spite
of being himself inertial. Is this just an approximation, and if so, up to what
extent can it be applied? The framework of special relativity is compared to an
amended form in which the fact of taking himself as a reference does not allow
the observer to overlook its own kinetics. So, the issue stands on which of two
formulations of the Lorentz gamma factor is the most accurate one: its standard
expression or an amended one which takes into account the fact that the
observer is himself inertial, while the former disregards it. When the observer
speed is ignored, the two formulations become identical. Hence, the standard
relativistic expression of gamma can be seen as an approximation applicable
when the observer motion is null or low, such as it is the instance on Earth.",1001.3039v1
2010-02-07,On the Boltzmann-Grad limit for the two dimensional periodic Lorentz gas,"The two-dimensional, periodic Lorentz gas, is the dynamical system
corresponding with the free motion of a point particle in a planar system of
fixed circular obstacles centered at the vertices of a square lattice in the
Euclidian plane. Assuming elastic collisions between the particle and the
obstacles, this dynamical system is studied in the Boltzmann-Grad limit,
assuming that the obstacle radius $r$ and the reciprocal mean free path are
asymptotically equivalent small quantities, and that the particle's
distribution function is slowly varying in the space variable. In this limit,
the periodic Lorentz gas cannot be described by a linear Boltzmann equation
(see [F. Golse, Ann. Fac. Sci. Toulouse 17 (2008), 735--749]), but involves an
integro-differential equation conjectured in [E. Caglioti, F. Golse, C.R. Acad.
Sci. S\'er. I Math. 346 (2008) 477--482] and proved in [J. Marklof, A.
Str\""ombergsson, preprint arXiv:0801.0612], set on a phase-space larger than
the usual single-particle phase-space. The main purpose of the present paper is
to study the dynamical properties of this integro-differential equation:
identifying its equilibrium states, proving a H Theorem and discussing the
speed of approach to equilibrium in the long time limit. In the first part of
the paper, we derive the explicit formula for a transition probability
appearing in that equation following the method sketched in [E. Caglioti, F.
Golse, loc. cit.].",1002.1463v3
2010-06-10,Gauge and Lorentz transformation placed on the same foundation,"In this note we show that a ""dynamical"" interaction for arbitrary spin can be
constructed in a straightforward way if gauge and Lorentz transformations are
placed on the same foundation. As Lorentz transformations act on space-time
coordinates, gauge transformations are applied to the gauge field. Placing
these two transformations on the same ground means that all quantized field
like spin-1/2 and spin-3/2 spinors are functions not only of the coordinates
but also of the gauge field components. This change of perspective solves a
couple of problems occuring for higher spin fields like the loss of causality,
bad high-energy properties and the deviation of the gyromagnetic ratio from its
constant value g=2 for any spin, as caused by applying the minimal coupling.
Starting with a ""dynamical"" interaction, a non-minimal coupling can be derived
which is consistent with causality, the expectation for the gyromagnetic ratio,
and well-behaved for high energies. As a consequence, on this stage the
(elektromagnetic) gauge field has to be considered as classical field.
Therefore, standard quantum field theory cannot be applied. Despite this
inconvenience, such a common ground is consistent with an old dream of
physicists almost a century ago. Our approach, therefore, indicates a
straightforward way to realize this dream.",1006.2039v2
2010-06-25,New constraints on Lorentz invariance violation from the neutron electric dipole moment,"We propose an original test of Lorentz invariance in the interaction between
a particle spin and an electromagnetic field and report on a first measurement
using ultracold neutrons. We used a high sensitivity neutron electric dipole
moment (nEDM) spectrometer and searched for a direction dependence of a nEDM
signal leading to a modulation of its magnitude at periods of 12 and 24 hours.
We constrain such a modulation to $d_{12} < 15 \times 10^{-25} \ e\,{\rm cm}$
and $d_{24} < 10 \times 10^{-25} \ e\,{\rm cm}$ at 95~\% C.L. The result
translates into a limit on the energy scale for this type of Lorentz violation
effect at the level of ${\cal E}_{LV} > 10^{10}$~GeV.",1006.4967v1
2010-07-22,Scalar field theory on kappa-Minkowski spacetime and translation and Lorentz invariance,"We investigate the properties of kappa-Minkowski spacetime by using
representations of the corresponding deformed algebra in terms of undeformed
Heisenberg-Weyl algebra. The deformed algebra consists of kappa-Poincare
algebra extended with the generators of the deformed Weyl algebra. The part of
deformed algebra, generated by rotation, boost and momentum generators, is
described by the Hopf algebra structure. The approach used in our
considerations is completely Lorentz covariant. We further use an adventages of
this approach to consistently construct a star product which has a property
that under integration sign it can be replaced by a standard pointwise
multiplication, a property that was since known to hold for Moyal, but not also
for kappa-Minkowski spacetime. This star product also has generalized trace and
cyclic properties and the construction alone is accomplished by considering a
classical Dirac operator representation of deformed algebra and by requiring it
to be hermitian. We find that the obtained star product is not translationally
invariant, leading to a conclusion that the classical Dirac operator
representation is the one where translation invariance cannot simultaneously be
implemented along with hermiticity. However, due to the integral property
satisfied by the star product, noncommutative free scalar field theory does not
have a problem with translation symmetry breaking and can be shown to reduce to
an ordinary free scalar field theory without nonlocal features and tachionic
modes and basicaly of the very same form. The issue of Lorentz invariance of
the theory is also discussed.",1007.3943v2
2010-08-02,Lorentz Violation in Warped Extra Dimensions,"Higher dimensional theories which address some of the problematic issues of
the Standard Model(SM) naturally involve some form of $D=4+n$-dimensional
Lorentz invariance violation (LIV). In such models the fundamental physics
which leads to, e.g., field localization, orbifolding, the existence of brane
terms and the compactification process all can introduce LIV in the higher
dimensional theory while still preserving 4-d Lorentz invariance. In this
paper, attempting to capture some of this physics, we extend our previous
analysis of LIV in 5-d UED-type models to those with 5-d warped extra
dimensions. To be specific, we employ the 5-d analog of the SM Extension of
Kostelecky et. al. ~which incorporates a complete set of operators arising from
spontaneous LIV. We show that while the response of the bulk scalar, fermion
and gauge fields to the addition of LIV operators in warped models is
qualitatively similar to what happens in the flat 5-d UED case, the gravity
sector of these models reacts very differently than in flat space.
Specifically, we show that LIV in this warped case leads to a non-zero bulk
mass for the 5-d graviton and so the would-be zero mode, which we identify as
the usual 4-d graviton, must necessarily become massive. The origin of this
mass term is the simultaneous existence of the constant non-zero $AdS_5$
curvature and the loss of general co-ordinate invariance via LIV in the 5-d
theory. Thus warped 5-d models with LIV in the gravity sector are not
phenomenologically viable.",1008.0380v4
2010-08-03,Very special relativity as relativity of dark matter: the Elko connection,"In the very special relativity (VSR) proposal by Cohen and Glashow, it was
pointed out that invariance under HOM(2) is both necessary and sufficient to
explain the null result of the Michelson-Morely experiment. It is the quantum
field theoretic demand of locality, or the requirement of P, T, CP, or CT
invariance, that makes invariance under the Lorentz group a necessity.
Originally it was conjectured that VSR operates at the Planck scale; we propose
that the natural arena for VSR is at energies similar to the standard model,
but in the dark sector. To this end we provide an ab initio spinor
representation invariant under the SIM(2) avatar of VSR and construct a mass
dimension one fermionic quantum field of spin one half. This field turns out to
be a very close sibling of Elko and it exhibits the same striking property of
intrinsic darkness with respect to the standard model fields. In the new
construct, the tension between Elko and Lorentz symmetries is fully resolved.
We thus entertain the possibility that the symmetries underlying the standard
model matter and gauge fields are those of Lorentz, while the event space
underlying the dark matter and the dark gauge fields supports the algebraic
structure underlying VSR.",1008.0436v2
2010-09-26,Probing the Effects of Lorentz-Symmetry Violating Chern-Simons and Ricci-Cotton Terms in Higher Derivative Gravity,"The combined effects of the Lorentz-symmetry violating Chern-Simons and
Ricci-Cotton actions are investigated for the Einstein-Hilbert gravity in the
second order formalism modified by higher derivative terms, and their
consequences on the spectrum of excitations are analyzed. We follow the lines
of previous works and build up an orthonormal basis of operators that splits
the fundamental fields according to their individual degrees of freedom. With
this new basis, the attainment of the propagators is remarkably simplified and
the identification of the physical and unphysical modes gets a new insight. Our
conclusion is that the only tachyon- and ghost-free model is the
Einstein-Hilbert action added up by the Chern-Simons term with a time-like
vector of the type $v^{\mu} = (\mu,\vec{0})$. Spectral consistency imposes taht
the Ricci-Cotton term must be switched off. We then infer that gravity with
Lorentz-symmetry violation imposes a drastically different constraint on the
background if compared to usual gauge theories whenever conditions for
suppression of tachyons and ghosts are required.",1009.5132v3
2010-10-26,Stringy Space-Time Foam and High-Energy Cosmic Photons,"In this review, I discuss briefly stringent tests of Lorentz-violating
quantum space-time foam models inspired from String/Brane theories, provided by
studies of high energy Photons from intense celestial sources, such as Active
Galactic Nuclei or Gamma Ray Bursts. The theoretical models predict
modifications to the radiation dispersion relations, which are quadratically
suppressed by the string mass scale, and time delays in the arrival times of
photons (assumed to be emitted more or less simultaneously from the source),
which are proportional to the photon energy, so that the more energetic photons
arrive later. Although the astrophysics at the source of these energetic
photons is still not understood, and such non simultaneous arrivals, that have
been observed recently, might well be due to non simultaneous emission as a
result of conventional physics effects, nevertheless, rather surprisingly, the
observed time delays can also fit excellently the stringy space-time foam
scenarios, provided the space-time defect foam is inhomogeneous. The key
features of the model, that allow it to evade a plethora of astrophysical
constraints on Lorentz violation, in sharp contrast to other field-theoretic
Lorentz-violating models of quantum gravity, are: (i) transparency of the foam
to electrons and in general charged matter, (ii) absence of birefringence
effects and (iii) a breakdown of the local effective lagrangian formalism.",1010.5399v1
2010-11-15,Quantum-Gravity Induced Lorentz Violation and Dynamical Mass Generation,"In Ref. [1] (by J. Alexandre) a minimal extension of (3+1)-dimensional
Quantum Electrodynamics has been proposed, which includes Lorentz-Violation
(LV) in the form of higher-(spatial)-derivative isotropic terms in the gauge
sector, suppressed by a mass scale $M$. The model can lead to dynamical mass
generation for charged fermions. In this article I elaborate further on this
idea and I attempt to connect it to specific quantum-gravity models, inspired
from string/brane theory. Specifically, in the first part of the article, I
comment briefly on the gauge dependence of the dynamical mass generation in the
approximations of [1], and I propose a possible avenue for obtaining the true
gauge-parameter-independent value of the mass by means of Pinch Technique
argumentations. In the second part of the work I embed the LV QED model into
multibrane world scenarios with a view to provide a geometrical way of
enhancing the dynamical mass to phenomenologically realistic values by means of
bulk warp metric factors, in an (inverse) Randall-Sundrum hierarchy. Finally in
the third part of this note, I demonstrate that such Lorentz Violating QED
models may represent parts of a low-energy effective action (of
Finsler-Born-Infeld type) of open strings propagating in quantum D0-particle
stochastic space-time foam backgrounds, which are viewed as consistent quantum
gravity configurations.",1011.3528v1
2010-11-30,Time separation as a hidden variable to the Copenhagen school of quantum mechanics,"The Bohr radius is a space-like separation between the proton and electron in
the hydrogen atom. According to the Copenhagen school of quantum mechanics, the
proton is sitting in the absolute Lorentz frame. If this hydrogen atom is
observed from a different Lorentz frame, there is a time-like separation
linearly mixed with the Bohr radius. Indeed, the time-separation is one of the
essential variables in high-energy hadronic physics where the hadron is a bound
state of the quarks, while thoroughly hidden in the present form of quantum
mechanics. It will be concluded that this variable is hidden in Feynman's rest
of the universe. It is noted first that Feynman's Lorentz-invariant
differential equation for the bound-state quarks has a set of solutions which
describe all essential features of hadronic physics. These solutions explicitly
depend on the time separation between the quarks. This set also forms the
mathematical basis for two-mode squeezed states in quantum optics, where both
photons are observable, but one of them can be treated a variable hidden in the
rest of the universe. The physics of this two-mode state can then be translated
into the time-separation variable in the quark model. As in the case of the
un-observed photon, the hidden time-separation variable manifests itself as an
increase in entropy and uncertainty.",1011.6595v1
2010-11-30,"Harmonic Generation in Metallic, GaAs-Filled Nanocavities in the Enhanced Transmission Regime at Visible and UV Wavelengths","We have conducted a theoretical study of harmonic generation from a silver
grating having slits filled with GaAs. By working in the enhanced transmission
regime, and by exploiting phase-locking between the pump and its harmonics, we
guarantee strong field localization and enhanced harmonic generation under
conditions of high absorption at visible and UV wavelengths. Silver is treated
using the hydrodynamic model, which includes Coulomb and Lorentz forces,
convection, electron gas pressure, plus bulk X(3) contributions. For GaAs we
use nonlinear Lorentz oscillators, with characteristic X(2) and X(3) and
nonlinear sources that arise from symmetry breaking and Lorentz forces. We find
that: (i) electron pressure in the metal contributes to linear and nonlinear
processes by shifting/reshaping the band structure; (ii) TEand TM-polarized
harmonics can be generated efficiently; (iii) the X(2) tensor of GaAs couples
TE- and TM-polarized harmonics that create phase-locked pump photons having
polarization orthogonal compared to incident pump photons; (iv) Fabry-Perot
resonances yield more efficient harmonic generation compared to plasmonic
transmission peaks, where most of the light propagates along external metal
surfaces with little penetration inside its volume. We predict conversion
efficiencies that range from 10-6 for second harmonic generation to 10-3 for
the third harmonic signal, when pump power is 2GW/cm2.",1011.6673v1
2010-12-15,Electron-Electron Interactions in Graphene: Current Status and Perspectives,"We review the problem of electron-electron interactions in graphene. Starting
from the screening of long range interactions in these systems, we discuss the
existence of an emerging Dirac liquid of Lorentz invariant quasi-particles in
the weak coupling regime, and strongly correlated electronic states in the
strong coupling regime. We also analyze the analogy and connections between the
many-body problem and the Coulomb impurity problem. The problem of the magnetic
instability and Kondo effect of impurities and/or adatoms in graphene is also
discussed in analogy with classical models of many-body effects in ordinary
metals. We show that Lorentz invariance plays a fundamental role and leads to
effects that span the whole spectrum, from the ultraviolet to the infrared. The
effect of an emerging Lorentz invariance is also discussed in the context of
finite size and edge effects as well as mesoscopic physics. We also briefly
discuss the effects of strong magnetic fields in single layers and review some
of the main aspects of the many-body problem in graphene bilayers. In addition
to reviewing the fully understood aspects of the many-body problem in graphene,
we show that a plethora of interesting issues remain open, both theoretically
and experimentally, and that the field of graphene research is still exciting
and vibrant.",1012.3484v2
2011-02-26,Spontaneously Generated Tensor Field Gravity,"An arbitrary local theory of a symmetric two-tensor field $H_{\mu \nu}$ in
Minkowski spacetime is considered, in which the equations of motion are
required to be compatible with a nonlinear length-fixing constraint $H_{\mu
\nu}^{2}=\pm M^{2}$ leading to spontaneous Lorentz invariance violation, SLIV
($M$ is the proposed scale for SLIV). Allowing the parameters in the Lagrangian
to be adjusted so as to be consistent with this constraint, the theory turns
out to correspond to linearized general relativity in the weak field
approximation, while some of the massless tensor Goldstone modes appearing
through SLIV are naturally collected in the physical graviton. In essence the
underlying diffeomophism invariance emerges as a necessary condition for the
tensor field $H_{\mu \nu}$ not to be superfluously restricted in degrees of
freedom, apart from the constraint due to which the true vacuum in the theory
is chosen by SLIV. The emergent theory appears essentially nonlinear, when
expressed in terms of the pure Goldstone tensor modes and contains a plethora
of new Lorentz and $CPT$ violating couplings. However, these couplings do not
lead to physical Lorentz violation once this tensor field gravity is properly
extended to conventional general relativity.",1102.5440v3
2011-03-24,Global geometry and topology of spacelike stationary surfaces in the 4-dimensional Lorentz space,"For spacelike stationary (i.e. zero mean curvature) surfaces in 4-dimensional
Lorentz space one can naturally introduce two Gauss maps and Weierstrass
representation. In this paper we investigate their global geometry
systematically. The total Gaussian curvature is related with the surface
topology as well as the indices of the so-called good singular ends by a
generalized Jorge-Meeks formula. On the other hand, as shown by a family of
counter-examples to Osserman's theorem, finite total curvature no longer
implies that Gauss maps extend to the ends. Interesting examples include the
generalization of the classical catenoids, helicoids, the Enneper surface, and
Jorge-Meeks' k-noids. Any of them could be embedded in the 4-dimensional
Lorentz space, showing a sharp contrast with the case of 3-dimensional
Euclidean space.",1103.4700v6
2011-04-23,Lorentz invariant dark-spinor and inflation,"We investigate the possibility of the inflation driven by a Lorentz invariant
non-standard spinor field. As these spinors are having dominant interaction via
gravitational field only, they are considered as \emph{Dark Spinors}. We study
how these dark-spinors can drive the inflation and investigate the cosmological
(scalar) perturbations generated by them. Though the dark-spinors obey a
Klein-Gordon like equation, the underlying theory of the cosmological
perturbations is far more complex than the theories which are using a canonical
scalar field. For example the sound speed of the perturbations is not a
constant but varies with time. We find that in order to explain the observed
value of the spectral-index $n_s$ one must have upper bound on the values of
the background NSS-field. The tensor to scalar ratio remains as small as that
in the case of canonical scalar field driven inflation because the correction
to tensor spectrum due to NSS is required to be very small. In addition we
discuss the relationship of results with previous results obtained by using the
Lorentz invariance violating theories.",1104.4574v3
2011-05-18,Fermion condensates and Lorentz symmetry breaking in strongly-coupled large N gauge theories,"The possibility of Lorentz symmetry breaking (LSB) has attracted considerable
attention in recent years. Spontaneous LSB, in particular, offers the
attractive prospect of the graviton as a Nambu-Golstone boson. Here we consider
the question of spontaneous LSB in lattice gauge theories via formation of
fermion condensates in the strong coupling and large N limits. We employ naive
massless fermions in a fermionic hopping expansion in the presence of sources
coupled to various condensate operators of interest. The expansion is summed in
the large N limit in two equivalent ways: (i) direct summation of all leading N
graphs; and (ii) construction of the corresponding large N effective action for
composite operators. When sources are turned off a variety of fermionic
condensates is found to persist. These include the chiral symmetry breaking
condensates, thus recovering previous results, but also some LSB condensates,
in particular, axial vector and rank-2 tensor condensates. Furthermore, in the
presence of internal (global) symmetry groups, formation of condensates
""locking"" internal and external (Lorentz subgroup) symmetries is found to also
become possible. Some implications and open questions are briefly discussed.",1105.3720v2
2011-07-13,Dimensional reduction of the CPT-even electromagnetic sector of the Standard Model Extension,"The CPT-even abelian gauge sector of the Standard Model Extension is
represented by the Maxwell term supplemented by
$(K_{F})_{\mu\nu\rho\sigma}F^{\mu\nu}F^{\rho\sigma}$, where the
Lorentz-violating background tensor, $(K_{F})_{\mu\nu\rho\sigma}$, possesses
the symmetries of the Riemann tensor. In the present work, we examine the
planar version of this theory, obtained by means of a typical dimensional
reduction procedure to $(1+2)$ dimensions. The resulting planar electrodynamics
is composed of a gauge sector containing six Lorentz-violating coefficients, a
scalar field endowed with a noncanonical kinetic term, and a coupling term that
links the scalar and gauge sectors. The dispersion relation is exactly
determined, revealing that the six parameters related to the pure
electromagnetic sector do not yield birefringence at any order. In this model,
the birefringence may appear only as a second order effect associated with the
coupling tensor linking the gauge and scalar sectors.The equations of motion
are written and solved in the stationary regime. The Lorentz-violating
parameters do not alter the asymptotic behavior of the fields but induce an
angular dependence not observed in the Maxwell planar theory.",1107.2664v1
2011-08-19,Constraint on parameters of the Inverse Compton Scattering model for radio pulsars,"The inverse Compton scattering (ICS) model can explain various pulse profile
shapes and diversity of pulse profile evolution based on the mechanism that the
radio emission is generated through inverse Compton scattering between
secondary relativistic particles and radio waves from polar gap avalanches. In
this paper, we study the parameter space of ICS model for 15 pulsars, which
share the common pulse profile evolution phenomena that the pulse profiles are
narrower at higher observing frequencies. Two key parameters, the initial
Lorentz factor and the energy loss factor of secondary particles are
constrained using the least square fitting method, where we fit the theoretical
curve of the ""beam-frequency mapping"" of the ICS model to the observed pulse
widths at multiple frequencies. The uncertainty of the inclination and viewing
angles are taken into account in the fitting process. It is found that the
initial Lorentz factor is larger than 4000, and the energy loss factor is
between 20 and 560. The Lorentz factor is consistent with the prediction of the
inner vacuum gap model. Such high energy loss factors suggest significant
energy loss for secondary particles at altitudes of a few tens to hundreds of
kilometers.",1108.3939v1
2011-10-03,Background Dependent Lorentz Violation from String Theory,"We revisit Lorentz violation in the Type IIB string theory with D3-branes and
D7-branes. We study the relativistic particle velocities in details, and show
that there exist both subluminal and superluminal particle propagations. In
particular, the additional contributions to the particle velosity \delta
v\equiv (v-c)/c from string theory is proportional to both the particle energy
and the D3-brane number density, and is inversely proportional to the string
scale. Thus, we can realize the background dependent Lorentz violation
naturally by varying the D3-brane number density in space time. To explain the
superluminal neutrino propagations in the OPERA and MINOS experiments, the
string scale should be around 10^5 GeV. With very tiny D3-brane number density
on the interstellar scale, we can also explain the time delays for the high
energy photons compared to the low energy photons in the MAGIC, HESS, and FERMI
experiments simultaneously. Interestingly, we can automatically satisfy all the
stringent constraints from the synchrotron radiation of the Crab Nebula, the
SN1987a observations on neutrinos, and the cosmic ray experiments on charged
leptons. We also address the possible phenomenological challenges to our models
from the relevant experiments done on the Earth.",1110.0451v2
2011-10-21,Physical Properties of Jets in AGN,"I review constraints on the physical properties of AGN jets revealed through
Very Long Baseline Interferometry (VLBI) studies of the structure and
time-evolution of parsec-scale jets, including recent results from the MOJAVE
program. In particular I focus on constraints available from very long time
baseline studies which probe a wide range of jet behavior over many outbursts.
Kinematic studies of propagating jet features find an apparent speed
distribution that peaks around 10c for blazars, with speeds up to 50c observed.
These observed speeds require Lorentz factors at least as large, implying that
parsec-scale Lorentz factors up to 10-20 are common for blazars with a tail up
to ~ 50. Jet flows are still becoming organized on these scales as evidenced by
the high incidence of non-radial motions and/or accelerations of jet features
(including increases and decreases in apparent speed and direction). Changes in
Lorentz factors of propagating jet features appear to play a significant role
in the observed accelerations, and while the connection between acceleration of
jet features and the underlying flow is not clear, the pattern of observed
accelerations suggest the flow may increase in speed near the base of the jet
and decrease further out. In some jets, ejections of new features span a range
of ejection angles over many epochs, tracing out wider opening angles on
parsec-scales than are apparent in single epoch observations.",1110.4852v1
2012-02-09,The Lorentz-invariant boundary action of the confining string and its universal contribution to the inter-quark potential,"We study the boundary contribution to the low energy effective action of the
open string describing the confining flux tube in gauge theories. The form of
the boundary terms is strongly constrained by the requirement of Lorentz
symmetry, which is spontaneously broken by the formation of a long confining
flux tube in the vacuum. Writing the boundary action as an expansion in the
derivatives of the Nambu-Goldstone modes describing the transverse fluctuations
of the string, we single out and put in a closed form the first few Lorentz
invariant boundary terms. We also evaluate the leading deviation from the
Nambu-Goto string produced by the boundary action on the vacuum expectation
value of the Wilson loop and we test this prediction in the 3d Ising gauge
model. Our simulation attains a level of precision which is sufficient to test
the contribution of this term.",1202.1984v3
2012-03-09,"The ""tetrad only"" theory space: Nonperturbative renormalization flow and Asymptotic Safety","We set up a nonperturbative gravitational coarse graining flow and the
corresponding functional renormalization group equation on the as to yet
unexplored ""tetrad only"" theory space. It comprises action functionals which
depend on the tetrad field (along with the related background and ghost fields)
and are invariant under the semi-direct product of spacetime diffeomorphisms
and local Lorentz transformations. This theory space differs from that of
Quantum Einstein Gravity (QEG) in that the tetrad rather than the metric
constitutes the fundamental variable and because of the additional symmetry
requirement of local Lorentz invariance. It also differs from ""Quantum Einstein
Cartan Gravity"" (QECG) investigated recently since the spin connection is not
an independent field variable now. We explicitly compute the renormalization
group flow on this theory space within the tetrad version of the
Einstein-Hilbert truncation. A detailed comparison with analog results in QEG
and QECG is performed in order to assess the impact the choice of a fundamental
field variable has on the renormalization behavior of the gravitational average
action, and the possibility of an asymptotically safe infinite cutoff limit is
investigated. Implications for nonperturbative studies of fermionic matter
coupled to quantum gravity are also discussed. It turns out that, in the
context of functional flow equations, the ""hybrid calculations"" proposed in the
literature (using the tetrad for fermionic diagrams only, and the metric in all
others) are unlikely to be quantitatively reliable. Moreover we find that,
unlike in perturbation theory, the non-propagating Faddeev-Popov ghosts related
to the local Lorentz transformations may not be discarded but rather contribute
quite significantly to the beta functions of Newton's constant and the
cosmological constant.",1203.2158v1
2012-03-17,Magneto--Acoustic Energetics Study of the Seismically Active Flare of 15 February 2011,"Multi--wavelength studies of energetic solar flares with seismic emissions
have revealed interesting common features between them. We studied the first
GOES X--class flare of the 24th solar cycle, as detected by the Solar Dynamics
Observatory (SDO). For context, seismic activity from this flare
(SOL2011-02-15T01:55-X2.2, in NOAA AR 11158) has been reported in the
literature (Kosovichev, 2011; Zharkov et al., 2011). Based on Dopplergram data
from the Helioseismic and Magnetic Imager (HMI), we applied standard methods of
local helioseismology in order to identify the seismic sources in this event.
RHESSI hard X-ray data are used to check the correlation between the location
of the seismic sources and the particle precipitation sites in during the
flare. Using HMI magnetogram data, the temporal profile of fluctuations in the
photospheric line-of-sight magnetic field is used to estimate the magnetic
field change in the region where the seismic signal was observed. This leads to
an estimate of the work done by the Lorentz-force transient on the photosphere
of the source region. In this instance this is found to be a significant
fraction of the acoustic energy in the attendant seismic emission, suggesting
that Lorentz forces can contribute significantly to the generation of
sunquakes. However, there are regions in which the signature of the
Lorentz-force is much stronger, but from which no significant acoustic emission
emanates.",1203.3907v1
2012-03-28,Characterisation and representation of non-dissipative electromagnetic medium with a double light cone,"We study Maxwell's equations on a 4-manifold N with a medium that is
non-dissipative and has a linear and pointwise response. In this setting, the
medium can be represented by a suitable (2,2)-tensor on the 4-manifold N.
Moreover, in each cotangent space on N, the medium defines a Fresnel surface.
Essentially, the Fresnel surface is a tensorial analogue of the dispersion
equation that describes the response of the medium for signals in the geometric
optics limit. For example, in isotropic medium the Fresnel surface is at each
point a Lorentz light cone. In a recent paper, I. Lindell, A. Favaro and L.
Bergamin introduced a condition that constrains the polarisation for plane
waves. In this paper we show (under suitable assumptions) that a slight
strengthening of this condition gives a pointwise characterisation of all
medium tensors for which the Fresnel surface is the union of two distinct
Lorentz null cones. This is for example the behaviour of uniaxial medium like
calcite. Moreover, using the representation formulas from Lindell et al. we
obtain a closed form representation formula that pointwise parameterises all
medium tensors for which the Fresnel surface is the union of two distinct
Lorentz null cones. Both the characterisation and the representation formula
are tensorial and do not depend on local coordinates.",1203.6336v1
2012-06-06,On Emergent Gauge and Gravity Theories,"We present some general approach to emergent gauge theories and consider in
significant detail the emergent tensor field gravity case. In essence, an
arbitrary local theory of a symmetric two-tensor field $H_{\mu \nu}$ in
Minkowski spacetime is considered, in which the equations of motion are
required to be compatible with a nonlinear $\sigma $ model type length-fixing
constraint $H_{\mu \nu}^{2}=\pm M^{2}$ leading to spontaneous Lorentz
invariance violation, SLIV ($M$ is the proposed scale for SLIV). Allowing the
parameters in the Lagrangian to be adjusted so as to be consistent with this
constraint, the theory turns out to correspond to linearized general relativity
in the weak field approximation, while some of the massless tensor Goldstone
modes appearing through SLIV are naturally collected in the physical graviton.
The underlying diffeomophism invariance emerges as a necessary condition for
the tensor field $H_{\mu \nu}$ not to be superfluously restricted in degrees of
freedom, apart from the constraint due to which the true vacuum in the theory
is chosen by SLIV. The emergent theory appears essentially nonlinear, when
expressed in terms of the pure Goldstone tensor modes and contains a plethora
of new Lorentz and $CPT$ violating couplings. However, these couplings do not
lead to physical Lorentz violation once this tensor field gravity is properly
extended to conventional general relativity.",1206.1368v1
2012-07-10,MALTS: A tool to simulate Lorentz Transmission Electron Microscopy from micromagnetic simulations,"Here we describe the development of the MALTS software which is a generalised
tool that simulates Lorentz Transmission Electron Microscopy (LTEM) contrast of
thin magnetic nanostructures. Complex magnetic nanostructures typically have
multiple stable domain structures. MALTS works in conjunction with the open
access micromagnetic software Object Oriented Micromagnetic Framework or MuMax.
Magnetically stable trial magnetisation states of the object of interest are
input into MALTS and simulated LTEM images are output. MALTS computes the
magnetic and electric phases accrued by the transmitted electrons via the
Aharonov-Bohm expressions. Transfer and envelope functions are used to simulate
the progression of the electron wave through the microscope lenses. The final
contrast image due to these effects is determined by Fourier Optics. Similar
approaches have been used previously for simulations of specific cases of LTEM
contrast. The novelty here is the integration with micromagnetic codes via a
simple user interface enabling the computation of the contrast from any
structure. The output from MALTS is in good agreement with both experimental
data and published LTEM simulations. A widely-available generalized code for
the analysis of Lorentz contrast addresses is a much needed step towards the
use of LTEM as a standardized laboratory technique.",1207.2310v2
2012-08-04,Resolution of the Abraham-Minkowski Controversy,"The momentum of light inside ponderable media has an electromagnetic part and
a mechanical part. The local and instantaneous density of the electromagnetic
part of the momentum is given by the Poynting vector divided by the square of
the speed of light in vacuum, irrespective of the nature of the electromagnetic
fields or the local or global properties of the material media. The mechanical
part of the momentum is associated with the action of the electromagnetic field
on the atomic constituents of the media, as specified by the Lorentz law of
force. Proper interpretation and application of the Maxwell-Lorentz equations
within the material bodies as well as at their surfaces and interfaces is all
that is needed to obtain a complete picture of the momentum of light, including
detailed numerical values at each and every point in space and time. That the
Abraham-Minkowski controversy surrounding the momentum of light inside material
media has persisted for nearly a century is due perhaps to an insufficient
appreciation for the completeness and consistency of the macroscopic
Maxwell-Lorentz theory, inadequate treatment of the electromagnetic force and
torque at the material boundaries, and an undue emphasis on the necessity of
coupling the equations of electrodynamics to those of the theory of elasticity
for proper treatment of mechanical momentum. The present paper reports the
resolution of the Abraham-Minkowski controversy within the framework of the
classical theory of electrodynamics, without resort to such complicating and
ultimately unnecessary factors as pseudo-momentum, special surface forces,
alternative energy-momentum tensors, and hidden momenta, that have caused so
much confusion for such a long period of time.",1208.0872v1
2012-08-21,Relativistic Jets in the Radio Reference Frame Image Database II: Blazar Jet Accelerations from the First 10 Years of Data (1994 - 2003),"(Abridged) We analyze blazar jet apparent speeds and accelerations from the
RDV series of astrometric and geodetic VLBI experiments. From these
experiments, we have produced and analyzed 2753 global VLBI images of 68
sources at 8 GHz with a median beam size of 0.9 milliarcseconds (mas), and a
median of 43 epochs per source. From this sample, we analyze the motions of 225
jet components in 66 sources. The distribution of the fastest measured apparent
speed in each source has a median of 8.3c and a maximum of 44c. Sources in the
2FGL Fermi LAT catalog display higher apparent speeds than those that have not
been detected. On average, components farther from the core in a given source
have significantly higher apparent speeds than components closer to the core.
We measure accelerations of components in orthogonal directions parallel and
perpendicular to their average velocity vector. Parallel accelerations have
significantly larger magnitudes than perpendicular accelerations, implying
observed accelerations are predominantly due to changes in the Lorentz factor
(bulk or pattern) rather than projection effects from jet bending. Positive
parallel accelerations are significantly more common than negative ones, so the
Lorentz factor (bulk or pattern)tends to increase on the scales observed here.
Observed parallel accelerations correspond to modest source frame increases in
the bulk or pattern Lorentz factor.",1208.4399v1
2012-08-30,Noncommutativity in (2+1)-dimensions and the Lorentz group,"In this article we considered models of particles living in a
three-dimensional space-time with a nonstandard noncommutativity induced by
shifting canonical coordinates and momenta with generators of a unitary
irreducible representation of the Lorentz group. The Hilbert space gets the
structure of a direct product with the representation space, where we are able
to construct operators which realize the algebra of Lorentz transformations. We
study the modified Landau problem for both Schr\""odinger and Dirac particles,
whose Hamiltonians are obtained through a kind of non-Abelian Bopp's shift of
the dynamical variables from the ones of the usual problem in the normal space.
The spectrum of these models are considered in perturbation theory, both for
small and large noncommutativity parameters. We find no constraint between the
parameters referring to no-commutativity in coordinates and momenta but they
rather play similar roles. Since the representation space of the unitary
irreducible representations SL(2,R) can be realized in terms of spaces of
square-integrable functions, we conclude that these models are equivalent to
quantum mechanical models of particles living in a space with an additional
compact dimension.",1208.6315v2
2012-11-09,GRBs have preferred jet opening angles and bulk Lorentz factors,"We recently found that Gamma Ray Burst energies and luminosities, in their
comoving frame, are remarkably similar. This, coupled with the clustering of
energetics once corrected for the collimation factor, suggests the possibility
that all bursts, in their comoving frame, have the same peak energy E'peak (of
the order of a few keV) and the same energetics of the prompt emission E'gamma
(of the order of 2e48 erg). The large diversity of bursts energies is then due
to the different bulk Lorentz factor Gamma and jet aperture angle theta_jet. We
investigated, through a population synthesis code, what are the distributions
of Gamma and theta_jet compatible with the observations. Both quantities must
have preferred values, with log-normal best fitting distributions and <Gamma0>
~ 275 and <\theta_jet> ~ 8.7 degree. Moreover, the peak values of the Gamma and
theta_jet distributions must be related - theta_jet^2.5 Gamma =const: the
narrower the jet angle, the larger the bulk Lorentz factor. We predict that ~6%
of the bursts that point to us should not show any jet break in their afterglow
light curve since they have sin(theta_jet)<1/Gamma. Finally, we estimate that
the local rate of GRBs is ~0.3% of all local SNIb/c and ~2.5% of local
hypernovae, i.e. SNIb/c with broad absorption lines.",1211.2062v1
2012-11-20,A fields only version of the Lorentz Force Law: Particles replaced by their fields,"We show that the Lorentz force law, F^L_1=q_1(E+v_1xB) being the charge on
particle 1 interacting with the electromagnetic fields due to all other
particles, can be written in a pure field form F^L_1=-\nabla_1 U^{EM}. In this
expression U^{EM} is the total electromagnetic energy of the system of particle
1 and all other particles. In deriving this result we review the old but not
widely known results that Maxwell's equations follow uniquely from Special
Relativity, and that the Lorentz force law follows from applying Hamilton's
variational principle to this result.
  For a two particle system, the standard view is that the electromagnetic
force on particle 1 is the result of the charge of particle 1 interacting
locally with the field of particle 2, and conversely. Both charges 1 and 2, and
fields 1 and 2 are needed. In our approach, the fields of all particles
contribute to the electromagnetic interaction everywhere, over all of space.
The charges of the particles do not enter the theory except incidentally, via
Gauss's law. This has novel interpretational consequences. In particular, it
allows a charged particle to be replaced by its electric and magnetic fields,
much as a particle in quantum mechanics is replaced by its complex valued
wavefunction.",1211.6072v1
2013-01-08,Contracted Lorentz invariance for gravity with a preferred foliation,"In canonical gravity, the choice of a local time direction is not obviously
compatible with local Lorentz invariance. One way to address this issue is to
view gravity as a gauge theory on observer space, rather than spacetime. In a
Lorentz covariant theory observer space is the space of unit future-directed
timelike vectors; picking such a vector locally breaks the symmetry to a
subgroup SO(D) of SO(D,1), so that on observer space the local symmetry group
is SO(D). Observer space geometries naturally describe any gravitational theory
that only assumes local invariance under SO(D). Here we construct
nonrelativistic observer spaces for gravity with a fixed foliation, applicable
to preferred foliation theories such as Horava-Lifshitz gravity. Different
Horava-Lifshitz observers at a point are related by a change in the shift
vector, leaving the preferred foliation invariant. Gravity is formulated on a
non-relativistic frame bundle with structure group ISO(D); the shift vector
acts as a symmetry breaking field breaking ISO(D) symmetry spontaneously to
SO(D). A natural torsion-free connection is constructed, including the usual
SO(D,1) connection of relativistic gravity plus terms depending on derivatives
of the shift vector. This observer space geometry provides a novel geometric
framework for the study of preferred foliation theories.",1301.1692v3
2013-01-09,Emergence of complex and spinor wave functions in Scale Relativity. II. Lorentz invariance and bi-spinors,"Owing to the non-differentiable nature of the theory of Scale Relativity, the
emergence of complex wave functions, then of spinors and bi-spinors occurs
naturally in its framework. The wave function is here a manifestation of the
velocity field of geodesics of a continuous and non-differentiable (therefore
fractal) space-time. In a first paper (Paper I), we have presented the general
argument which leads to this result using an elaborate and more detailed
derivation than previously displayed. We have therefore been able to show how
the complex wave function emerges naturally from the doubling of the velocity
field and to revisit the derivation of the non relativistic Schr\""odinger
equation of motion. In the present paper (Paper II) we deal with relativistic
motion and detail the natural emergence of the bi-spinors from such first
principles of the theory. Moreover, while Lorentz invariance has been up to now
inferred from mathematical results obtained in stochastic mechanics, we display
here a new and detailed derivation of the way one can obtain a Lorentz
invariant expression for the expectation value of the product of two
independent fractal fluctuation fields in the sole framework of the theory of
Scale Relativity. These new results allow us to enhance the robustness of our
derivation of the two main equations of motion of relativistic quantum
mechanics (the Klein-Gordon and Dirac equations) which we revisit here at
length.",1301.2186v2
2013-01-23,Constraints on the Synchrotron Emission Mechanism in GRBs,"We reexamine the general synchrotron model for GRBs' prompt emission and
determine the regime in the parameter phase space in which it is viable. We
characterize a typical GRB pulse in terms of its peak energy, peak flux and
duration and use the latest Fermi observations to constrain the high energy
part of the spectrum. We solve for the intrinsic parameters at the emission
region and find the possible parameter phase space for synchrotron emission.
Our approach is general and it does not depend on a specific energy dissipation
mechanism. Reasonable synchrotron solutions are found with energy ratios of
$10^{-4}<\epsilon_B/\epsilon_e<10$, bulk Lorentz factor values of
$300<\Gamma<3000$, typical electrons' Lorentz factor values of $3\times
10^3<\gamma_e<10^5$ and emission radii of the order $10^{15}cm<R<10^{17}$cm.
Most remarkable among those are the rather large values of the emission radius
and the electron's Lorentz factor. We find that soft (with peak energy less
than 100KeV) but luminous (isotropic luminosity of $~1.5 \times 10^{53}$)
pulses are inefficient. This may explain the lack of strong soft bursts. In
cases when most of the energy is carried out by the kinetic energy of the flow,
such as in the internal shocks, the synchrotron solution requires that only a
small fraction of the electrons are accelerated to relativistic velocities by
the shocks. We show that future observations of very high energy photons from
GRBs by CTA, could possibly determine all parameters of the synchrotron model
or rule it out altogether.",1301.5575v2
2013-03-06,The Kinematics and Ionization of Nuclear Gas Clouds in Centaurus A,"Neumayer et al. established the existence of a blue-shifted cloud in the core
of Centaurus A, within a few parsecs of the nucleus and close to the radio jet.
We propose that the cloud has been impacted by the jet, and that it is in the
foreground of the jet, accounting for its blue-shifted emission on the Southern
side of the nucleus. We consider both shock excitation and photoionization
models for the excitation of the cloud. Shock models do not account for the
[SiVI] and [CaVIII] emission line fluxes. However, X-ray observations indicate
a source of ionizing photons in the core of Centaurus A; photoionization by the
inferred flux incident on the cloud can account for the fluxes in these lines
relative to Brackett-gamma. The power-law slope of the ionizing continuum
matches that inferred from synchrotron models of the X-rays. The logarithm of
the ionization parameter is -1.9, typical of that in Seyfert galaxies and
consistent with the value proposed for dusty ionized plasmas. The model cloud
density depends upon the Lorentz factor of the blazar and the inclination of
our line of sight to the jet axis. For acute inclinations, the inferred density
is consistent with expected cloud densities. However, for moderate inclinations
of the jet to the line of sight, high Lorentz factors imply cloud densities in
excess of $10^5 cm^{-3}$ and very low filling factors, suggesting that models
of the gamma ray emission should incorporate jet Lorentz factors $\lesssim 5$.",1303.1236v1
2013-03-31,Opening Angles of Collapsar Jets,"We investigate the jet propagation and breakout from the stellar progenitor
for gamma-ray burst (GRB) collapsars by performing two-dimensional relativistic
hydrodynamic simulations and analytical modeling. We find that the jet opening
angle is given by $\theta_j \sim 1/5 \Gamma_{0}$, and infer the initial Lorentz
factor of the jet at the central engine, $\Gamma_0$, is a few for existing
observations of $\theta_j$. The jet keeps the Lorentz factor low inside the
star by converging cylindrically via collimation shocks under the cocoon
pressure, and accelerates at jet breakout before the free expansion to a
hollow-cone structure. In this new picture the GRB duration is determined by
the sound crossing time of the cocoon, after which the opening angle widens,
reducing the apparent luminosity. Some bursts violating the maximum opening
angle $\theta_{j,\max}\sim 1/5 \sim 12^{\circ}$ imply the existence of a
baryon-rich sheath or a long-acting jet. We can explain the slopes in both
Amati and Yonetoku spectral relations using an off-centered photosphere model,
if we make only one assumption that the total jet luminosity is proportional to
the initial Lorentz factor of the jet. We also numerically calibrate the
pre-breakout model (Bromberg et al.) for later use.",1304.0163v5
2013-04-30,Cosmological constraints on Lorentz violating dark energy,"The role of Lorentz invariance as a fundamental symmetry of nature has been
lately reconsidered in different approaches to quantum gravity. It is thus
natural to study whether other puzzles of physics may be solved within these
proposals. This may be the case for the cosmological constant problem. Indeed,
it has been shown that breaking Lorentz invariance provides Lagrangians that
can drive the current acceleration of the universe without experiencing large
corrections from ultraviolet physics. In this work, we focus on the simplest
model of this type, called ThetaCDM, and study its cosmological implications in
detail. At the background level, this model cannot be distinguished from
LambdaCDM. The differences appear at the level of perturbations. We show that
in ThetaCDM, the spectrum of CMB anisotropies and matter fluctuations may be
affected by a rescaling of the gravitational constant in the Poisson equation,
by the presence of extra contributions to the anisotropic stress, and finally
by the existence of extra clustering degrees of freedom. To explore these
modifications accurately, we modify the Boltzmann code CLASS. We then use the
parameter inference code Monte Python to confront ThetaCDM with data from
WMAP-7, SPT and WiggleZ. We obtain strong bounds on the parameters accounting
for deviations from LambdaCDM. In particular, we find that the discrepancy
between the gravitational constants appearing in the Poisson and Friedmann
equations is constrained at the level 1.8%.",1305.0009v1
2013-06-06,"Einstein's physical geometry at play: inertial motion, the boostability assumption, the Lorentz transformations, and the so-called conventionality of the one-way speed of light","In this work, Einstein's view of geometry as physical geometry is taken into
account in the analysis of diverse issues related to the notions of inertial
motion and inertial reference frame. Einstein's physical geometry enables a
non-conventional view on Euclidean geometry (as the geometry associated to
inertial motion and inertial reference frames) and on the uniform time. Also,
by taking into account the implications of the view of geometry as a physical
geometry, it is presented a critical reassessment of the so-called boostability
assumption (implicit according to Einstein in the formulation of the theory)
and also of 'alternative' derivations of the Lorentz transformations that do
not take into account the so-called 'light postulate'. Finally it is addressed
the issue of the eventual conventionality of the one-way speed of light or,
what is the same, the conventionality of simultaneity (within the same inertial
reference frame). It turns out that it is possible to see the (possible)
conventionality of distant simultaneity as a case of conventionality of
geometry (in Einstein's reinterpretation of Poincar\'e's views). By taking into
account synchronization procedures that do not make reference to light
propagation (which is necessary in the derivation of the Lorentz
transformations without the 'light postulate'), it can be shown that the
synchronization of distant clocks does not need any conventional element. This
implies that the whole of chronogeometry (and because of this the physical part
of the theory) does not have any conventional element in it, and it is a
physical chronogeometry.",1306.1361v2
2013-06-07,Strong constraints on magnetized white dwarfs surpassing the Chandrasekhar mass limit,"We show that recently proposed white dwarf models with masses well in excess
of the Chandrasekhar limit, based on modifying the equation of state by a
super-strong magnetic field in the centre, are very far from equilibrium
because of the neglect of Lorentz forces. An upper bound on the central
magnetic fields, from a spherically averaged hydrostatic equation, is much
smaller than the values assumed. Robust estimates of the Lorentz forces are
also made without assuming spherical averaging. These again bear out the
results obtained from a spherically averaged model. In our assessment, these
estimates rule out the possibility that magnetic tension could change the
situation in favor of larger magnetic fields. We conclude that such
super-Chandrasekhar models are unphysical and exploration of their
astrophysical consequences is premature.
  Erratum : We correct certain numerical estimates made in our paper. This
correction however does not alter the conclusion that when Lorentz forces are
taken into account the super-massive white dwarf models, obtained simply by
modifying the equation of state in presence of a super-strong magnetic field in
the centre, fail to be in equilibrium.",1306.1625v3
2013-07-08,On the Potential for General Relativity and its Geometry,"The unique ghost-free mass and nonlinear potential terms for general
relativity are presented in a diffeomorphism and local Lorentz invariant
vierbein formalism. This construction requires an additional two-index
Stuckelberg field, beyond the four scalar fields used in the metric
formulation, and unveils a new local SL(4) symmetry group of the mass and
potential terms, not shared by the Einstein-Hilbert term. The new field is
auxiliary but transforms as a vector under two different Lorentz groups, one of
them the group of local Lorentz transformations, the other an additional global
group. This formulation enables a geometric interpretation of the mass and
potential terms for gravity in terms of certain volume forms. Furthermore, we
find that the decoupling limit is much simpler to extract in this approach; in
particular, we are able to derive expressions for the interactions of the
vector modes. We also note that it is possible to extend the theory by
promoting the two-index auxiliary field into a Nambu-Goldstone boson
nonlinearly realizing a certain space-time symmetry, and show how it is ""eaten
up"" by the antisymmetric part of the vierbein.",1307.2245v2
2014-01-08,A mathematical and numerical framework for ultrasonically-induced Lorentz force electrical impedance tomography,"We provide a mathematical analysis and a numerical framework for Lorentz
force electrical conductivity imaging. Ultrasonic vibration of a tissue in the
presence of a static magnetic field induces an electrical current by the
Lorentz force. This current can be detected by electrodes placed around the
tissue; it is proportional to the velocity of the ultrasonic pulse, but depends
nonlinearly on the conductivity distribution. The imaging problem is to
reconstruct the conductivity distribution from measurements of the induced
current. To solve this nonlinear inverse problem, we first make use of a
virtual potential to relate explicitly the current measurements to the
conductivity distribution and the velocity of the ultrasonic pulse. Then, by
applying a Wiener filter to the measured data, we reduce the problem to imaging
the conductivity from an internal electric current density. We first introduce
an optimal control method for solving such a problem. A new direct
reconstruction scheme involving a partial differential equation is then
proposed based on viscosity-type regularization to a transport equation
satisfied by the current density field. We prove that solving such an equation
yields the true conductivity distribution as the regularization parameter
approaches zero. We also test both schemes numerically in the presence of
measurement noise, quantify their stability and resolution, and compare their
performance.",1401.2337v1
2013-12-24,Modified Einstein and Finsler Like Theories on Tangent Lorentz Bundles,"We study modifications of general relativity, GR, with nonlinear dispersion
relations which can be geometrized on tangent Lorentz bundles. Such modified
gravity theories, MGTs, can be modeled by gravitational Lagrange density
functionals $f(\mathbf{R},\mathbf{T},F)$ with generalized/ modified scalar
curvature $\mathbf{R}$, trace of matter field tensors $\mathbf{T}$ and modified
Finsler like generating function $F$. In particular, there are defined
extensions of GR with extra dimensional ""velocity/ momentum"" coordinates. For
four dimensional models, we prove that it is possible to decouple and integrate
in very general forms the gravitational fields for
$f(\mathbf{R},\mathbf{T},F)$-modified gravity using nonholonomic 2+2 splitting
and nonholonomic Finsler like variables $F$. We study the modified motion and
Newtonian limits of massive test particles on nonlinear geodesics approximated
with effective extra forces orthogonal to the four--velocity. We compute the
constraints on the magnitude of extra-accelerations and analyze perihelion
effects and possible cosmological implications of such theories. We also derive
the extended Raychaudhuri equation in the framework of a tangent Lorentz
bundle. Finally, we speculate on effective modelling of modified theories by
generic off-diagonal configurations in Einstein and/or MGTs and Finsler
gravity. We provide some examples for modified stationary (black) ellipsoid
configurations and locally anisotropic solitonic backgrounds.",1401.2879v2
2014-07-04,Status and prospects for $CPT$ and Lorentz invariance violation searches in neutral meson mixing,"An overview of current experimental bounds on $CPT$ violation in neutral
meson mixing is given. New values for the $CPT$ asymmetry in the $B^0$ and
$B_s^0$ systems are deduced from published BaBar, Belle and LHCb results. With
dedicated analyses, LHCb will be able to further improve the bounds on $CPT$
violation in the $D^0$, $B^0$ and $B_s^0$ systems. Since $CPT$ violation
implies violation of Lorentz invariance in an interacting local quantum field
theory, the observed $CPT$ asymmetry will exhibit sidereal- and boost-dependent
variations. Such $CPT$-violating and Lorentz-violating effects are accommodated
in the framework of the Standard-Model Extension (SME). The large boost of the
neutral mesons produced at LHCb results in a high sensitivity to the
corresponding SME coefficients. For the $B^0$ and $B_s^0$ systems, using
existing LHCb results, we determine with high precision the SME coefficients
that are not varying with sidereal time. With a full sidereal analysis, LHCb
will be able to improve the existing SME bounds in the $D^0$, $B^0$ and $B_s^0$
systems by up to two orders of magnitude.",1407.1269v3
2014-07-22,Temperature-driven band inversion in Pb$_{0.77}$Sn$_{0.23}$Se: Optical and Hall-effect studies,"Optical and Hall-effect measurements have been performed on single crystals
of Pb$_{0.77}$Sn$_{0.23}$Se, a IV-VI mixed chalcogenide. The temperature
dependent (10--300 K) reflectance was measured over 40--7000 cm$^{-1}$ (5--870
meV) with an extension to 15,500 cm$^{-1}$ (1.92 eV) at room temperature. The
reflectance was fit to the Drude-Lorentz model using a single Drude component
and several Lorentz oscillators. The optical properties at the measured
temperatures were estimated via Kramers-Kronig analysis as well as by the
Drude-Lorentz fit. The carriers were p-type with the carrier density determined
by Hall measurements. A signature of valence intraband transition is found in
the low-energy optical spectra. It is found that the valence-conduction band
transition energy as well as the free carrier effective mass reach minimum
values at 100 K, suggesting temperature-driven band inversion in the material.
Density function theory calculation for the electronic band structure also make
similar predictions.",1407.5726v1
2014-08-26,Universal horizons and black holes in gravitational theories with broken Lorentz symmetry,"In this paper, we first show that the definition of the universal horizons
studied recently in the khrononmetric theory of gravity can be
straightforwardly generalized to other theories that violate the Lorentz
symmetry, by simply considering the khronon as a probe field and playing the
same role as a Killing vector field. As an application, we study static charged
($D+1$)-dimensional spacetimes in the framework of the healthy
(non-projectable) Horava-Lifshitz (HL) gravity in the infrared limit, and find
various solutions. Some of them represent Lifshitz space-times with
hyperscaling violations, and some have black hole structures. In the latter
universal horizons always exist inside the Killing horizons. The surface
gravity on them can be either larger or smaller than the surface gravity on the
Killing horizons, depending on the space-times considered. Although such black
holes are found only in the infrared, we argue that black holes with universal
horizons also exist in the full theory of the HL gravity. A simple example is
the Schwarzschild solution written in the Painleve-Gullstrand coordinates,
which is also a solution of the full theory of the HL gravity and has a
universal horizon located inside the Schwarzschild Killing horizon.",1408.5976v3
2014-09-16,On the Electrodynamics of Moving Permanent Dipoles in External Electromagnetic Fields,"The classical theory of electrodynamics is built upon Maxwell's equations and
the concepts of electromagnetic field, force, energy and momentum, which are
intimately tied together by Poynting's theorem and the Lorentz force law.
Whereas Maxwell's macroscopic equations relate the electric and magnetic fields
to their material sources (i.e., charge, current, polarization and
magnetization), Poynting's theorem governs the flow of electromagnetic energy
and its exchange between fields and material media, while the Lorentz law
regulates the back-and-forth transfer of momentum between the media and the
fields. The close association of momentum with energy thus demands that the
Poynting theorem and the Lorentz law remain consistent with each other, while,
at the same time, ensuring compliance with the conservation laws of energy,
linear momentum, and angular momentum. This paper shows how a consistent
application of the aforementioned laws of electrodynamics to moving permanent
dipoles (both electric and magnetic) brings into play the rest-mass of the
dipoles. The rest mass must vary in response to external electromagnetic fields
if the overall energy of the system is to be conserved. The physical basis for
the inferred variations of the rest-mass appears to be an interference between
the internal fields of the dipoles and the externally applied fields. We use
two different formulations of the classical theory in which energy and momentum
relate differently to the fields, yet we find identical behavior for the
rest-mass in both formulations.",1409.4796v1
2014-09-19,On systems having Poincaré and Galileo symmetry,"Using the wave equation in d > or = 1 space dimensions it is illustrated how
dynamical equations may be simultaneously Poincar\'e and Galileo covariant with
respect to different sets of independent variables. This provides a method to
obtain dynamics-dependent representations of the kinematical symmetries. When
the field is a displacement function both symmetries have a physical
interpretation. For d = 1 the Lorentz structure is utilized to reveal hitherto
unnoticed features of the non-relativistic Chaplygin gas, including a
relativistic structure with a limiting case that exhibits the Carroll group,
and field-dependent symmetries and associated Noether charges. The Lorentz
transformations of the potentials naturally associated with the Chaplygin
system are given. These results prompt the search for further symmetries and it
is shown that the Chaplygin equations support a nonlinear superposition
principle. A known spacetime mixing symmetry is shown to decompose into
label-time and superposition symmetries. It is shown that a quantum mechanical
system in a stationary state behaves as a Chaplygin gas. The extension to d > 1
is used to illustrate how the physical significance of the dual symmetries is
contingent on the context by showing that Maxwells equations exhibit an exact
Galileo covariant formulation where Lorentz and gauge transformations are
represented by field-dependent symmetries. A natural conceptual and formal
framework is provided by the Lagrangian and Eulerian pictures of continuum
mechanics.",1409.5628v2
2014-09-11,Self-consistent theory for a plane wave in a moving medium and light-momentum criterion,"A self-consistent theory is developed based on the principle of relativity
for a plane wave in a moving non-dispersive, lossless, non-conducting,
isotropic, uniform medium. A light-momentum criterion is set up for the first
time, which states that the momentum of light in a medium is parallel to the
wave vector in all inertial frames of reference. By rigorous analysis, novel
basic properties of the plane wave are exposed: (a) Poynting vector does not
necessarily represent the electromagnetic (EM) power flow when a medium moves;
(b) Minkowski light momentum and energy constitute a Lorentz four-vector in a
form of single EM-field cell or single photon, and Planck constant is a Lorentz
invariant; (c) there is no momentum transfer taking place between the plane
wave and the uniform medium, and the EM momentum conservation equation cannot
be uniquely determined without resorting to the principle of relativity; and
(d) when the medium moves opposite to the wave vector at a
faster-than-dielectric light speed, negative frequency and negative EM energy
density occur, with the plane wave becoming left-handed. Finally, a new physics
of so-called ""intrinsic Lorentz violation"" is presented as well.",1409.5807v7
2014-11-11,A relativistically interacting exactly solvable multi-time model for two mass-less Dirac particles in 1+1 dimensions,"The question how to Lorentz transform an N-particle wave function naturally
leads to the concept of a so-called multi-time wave function, i.e. a map from
(space-time)^N to a spin space. This concept was originally proposed by Dirac
as the basis of relativistic quantum mechanics. In such a view, interaction
potentials are mathematically inconsistent. This fact motivates the search for
new mechanisms for relativistic interactions. In this paper, we explore the
idea that relativistic interaction can be described by boundary conditions on
the set of coincidence points of two particles in space-time. This extends
ideas from zero-range physics to a relativistic setting. We illustrate the idea
at the simplest model which still possesses essential physical properties like
Lorentz invariance and a positive definite density: two-time equations for
mass-less Dirac particles in 1+1 dimensions. In order to deal with a
spatio-temporally non-trivial domain, a necessity in the multi-time picture, we
develop a new method to prove existence and uniqueness of classical solutions:
a generalized version of the method of characteristics. Both mathematical and
physical considerations are combined to precisely formulate and answer the
questions of probability conservation, Lorentz invariance, interaction and
antisymmetry.",1411.2833v2
2014-11-21,Searching for Traces of Planck-Scale Physics with High Energy Neutrinos,"High energy cosmic neutrino observations provide a sensitive test of Lorentz
invariance violation, which may be a consequence of quantum gravity theories.
We consider a class of non-renormalizable, Lorentz invariance violating
operators that arise in an effective field theory description of Lorentz
invariance violation in the neutrino sector inspired by Planck-scale physics
and quantum gravity models. We assume a conservative generic scenario for the
redshift distribution of extragalactic neutrino sources and employ Monte Carlo
techniques to describe superluminal neutrino propagation, treating
kinematically allowed energy losses of superluminal neutrinos caused by both
vacuum pair emission and neutrino splitting. We consider EFTs with both
non-renormalizable CPT-odd and non-renormalizable CPT-even operator dominance.
We then compare the spectra derived using our Monte Carlo calculations in both
cases with the spectrum observed by IceCube in order to determine the
implications of our results regarding Planck-scale physics. We find that if the
drop off in the neutrino flux above ~2 PeV is caused by Planck scale physics,
rather than by a limiting energy in the source emission, a potentially
significant pileup effect would be produced just below the drop off energy in
the case of CPT-even operator dominance. However, such a clear drop off effect
would not be observed if the CPT-odd, CPT-violating term dominates.",1411.5889v3
2014-11-25,Introduction of the Lie group of Lorentz matrices in Special Relativity. Tangent boost along a worldline and its associated matrix in the Lie algebra. Applications,"In order to generalize the relativistic notion of boost to the case of non
inertial particles and to general relativity, we come back to the definition of
Lie group of Lorentz matrices and its Lie algebra and we study how this group
acts on the Minskowski space. We thus define the notion of tangent boost along
a worldline. This notion very general notion gives a useful tool both in
special relativity (for non inertial particles or/and for non rectilinear
coordinates) and in general relativity. We also introduce a matrix of the Lie
algebra which, together with the tangent boost, gives the whole dynamical
description of the considered system (acceleration and Thomas rotation). After
studying the properties of Lie algebra matrices and of their reduced forms, we
show that the Lie group of special Lorentz matrices has four one-parameter
subgroups. These tools lead us to introduce the Thomas rotation in a quite
general way. At the end of the paper, we present some examples using these
tools and we consider the case of an electron rotating on a circular orbit
around an atom nucleus. We then discuss the twin paradox and we show that when
the one who made a journey into space in a high-speed rocket returns home he is
not only younger than the twin who stayed on Earth but he is also disorientated
because his gyroscope has turned with respect to earth referential frame.",1411.7254v3
2014-12-07,New pulsar limit on local Lorentz invariance violation of gravity in the standard-model extension,"In the pure-gravity sector of the minimal standard-model extension, nine
Lorentz-violating coefficients of a vacuum-condensed tensor field describe
dominant observable deviations from general relativity, out of which eight were
already severely constrained by precision experiments with lunar laser ranging,
atom interferometry, and pulsars. However, the time-time component of the
tensor field, $\bar s^{\rm TT}$, dose not enter into these experiments, and was
only very recently constrained by Gravity Probe B. Here we propose a novel idea
of using the Lorentz boost between different frames to mix different components
of the tensor field, and thereby obtain a stringent limit of $\bar s^{\rm TT}$
from binary pulsars. We perform various tests with the state-of-the-art white
dwarf optical spectroscopy and pulsar radio timing observations, in order to
get new robust limits of $\bar s^{\rm TT}$. With the isotropic cosmic microwave
background as a preferred frame, we get $|\bar s^{\rm TT}| < 1.6 \times
10^{-5}$ (95\% CL), and without assuming the existence of a preferred frame, we
get $|\bar s^{\rm TT}| < 2.8 \times 10^{-4}$ (95\% CL). These two limits are
respectively about 500 times and 30 times better than the current best limit.",1412.2320v2
2014-12-22,Radiation from Particles Accelerated in Relativistic Jet Shocks and Shear-flows,"We have investigated particle acceleration and emission from shocks and shear
flows associated with an unmagnetized relativistic jet plasma propagating into
an unmagnetized ambient plasma. Strong electro-magnetic fields are generated in
the jet shock via the filamentation (Weibel) instability. Shock field strength
and structure depend on plasma composition (($e^{\pm}$ or $e^-$- $p^+$ plasmas)
and Lorentz factor. In the velocity shear between jet and ambient plasmas,
strong AC ($e^{\pm}$ plasmas) or DC ($e^-$- $p^+$ plasmas) magnetic fields are
generated via the kinetic Kelvin-Helmholtz instability (kKHI), and the magnetic
field structure also depends on the jet Lorentz factor. We have calculated,
self-consistently, the radiation from electrons accelerated in shock generated
magnetic fields. The spectra depend on the jet's initial Lorentz factor and
temperature via the resulting particle acceleration and magnetic field
generation. Our ongoing ""Global"" jet simulations containing shocks and velocity
shears will provide us with the ability to calculate and model the complex time
evolution and/or spectral structure observed from gamma-ray bursts, AGN jets,
and supernova remnants.",1412.7064v1
2015-02-19,Post-Newtonian constraints on Lorentz-violating gravity theories with a MOND phenomenology,"We study the post-Newtonian expansion of a class of Lorentz-violating gravity
theories that reduce to khronometric theory (i.e. the infrared limit of Horava
gravity) in high-acceleration regimes, and reproduce the phenomenology of the
modified Newtonian dynamics (MOND) in the low-acceleration, non-relativistic
limit. Like in khronometric theory, Lorentz symmetry is violated in these
theories by introducing a dynamical scalar field (the ""khronon"") whose gradient
is enforced to be timelike. As a result, hypersurfaces of constant khronon
define a preferred foliation of the spacetime, and the khronon can be thought
of as a physical absolute time. The MOND phenomenology arises as a result of
the presence, in the action, of terms depending on the acceleration of the
congruence orthogonal to the preferred foliation. We find that if the theory is
forced to reduce exactly to General Relativity (rather than to khronometric
theory) in the high-acceleration regime, the post-Newtonian expansion breaks
down at low accelerations, and the theory becomes strongly coupled.
Nevertheless, we identify a sizeable region of the parameter space where the
post-Newtonian expansion remains perturbative for all accelerations, and the
theory passes both solar-system and pulsar gravity tests, besides producing a
MOND phenomenology for the rotation curves of galaxies. We illustrate this
explicitly with a toy model of a system containing only baryonic matter but no
Dark Matter.",1502.05554v3
2015-02-19,UV properties of Galileons: Spectral Densities,"We propose a picture for the UV properties of Galileon field theories. We
conjecture that Galileons, and all theories incorporating the Vainshtein
mechanism, fall into Jaffe's class of `non-localizable' field theories
characterized by an exponential growth in their Kallen-Lehmann spectral
densities. Similar properties have been argued to arise for Little String
Theories and M-theory. For such theories, the notion of micro-causality and the
time ordering used to define the S-matrix and correlation functions must be
modified, and we give a Lorentz invariant prescription for how this can be
achieved. In common with General Relativity (GR), the scattering amplitudes for
Galileons are no longer expected to satisfy polynomial boundedness away from
the forward scattering or fixed physical momentum transfer limits. This is a
reflection of the fact that these theories are fundamentally gravitational and
not local field theories. We attribute this to the existence of a locality
bound for Galileons, analogous to the Giddings-Lippert locality bound for GR.
We utilize the recently developed Galileon duality to define a UV finite,
Lorentz invariant, quantization of a specific Galileon theory for which the
energy of all states are positive definite. We perform an explicit computation
of the Wightman functions for this theory, and demonstrate the exponential
growth associated with the locality bound. In analogy with GR, the bound is
correlated with the absence of Galileon Duality (i.e. Diffeomorphism) invariant
local observables. We argue that these theories can be quantized in a manner
which preserves Lorentz invariance and macro-causality and that the latter
ensures that the superluminalities found in the low energy effective theory are
absent in the full theory.",1502.05706v1
2015-04-16,Electroweak standard model with very special relativity,"The Very Special Relativity Electroweak Standard Model (VSR EW SM) is a
theory with $SU(2)_L \times U(1)_R$ symmetry, with the same number of leptons
and gauge fields as in the usual Weinberg-Salam (WS) model. No new particles
are introduced. The model is renormalizable and unitarity is preserved.
However, photons obtain mass and the massive bosons obtain different masses for
different polarizations. Besides, neutrino masses are generated. A VSR
invariant term will produce neutrino oscillations and new processes are
allowed. In particular, we compute the rate of the decays $\mu \rightarrow e +
\gamma$. All these processes, which are forbidden in the Electroweak Standard
Model, put stringent bounds on the parameters of our model and measure the
violation of Lorentz invariance. We investigate the canonical quantization of
this non-local model. Second quantization is carried out obtaining a well
defined particle concept. Additionally, we do a counting of the degrees of
freedom associated to the gauge bosons involved in this work, after Spontaneous
Symmetry Breaking has been realized. Violations of Lorentz invariance have been
predicted by several theories of Quantum Gravity \cite{amu}. It is a remarkable
possibility that the low energy effects of Lorentz violation induced by Quantum
Gravity could be contained in the non-local terms of the VSR EW SM.",1504.04222v1
2015-05-14,"Supersymmetric 3D model for gravity with $SU(2)$ gauge symmetry, mass generation and effective cosmological constant","A Chern--Simons system in $2+1$ dimensions invariant under local Lorentz
rotations, $SU(2)$ gauge transformations, and local $\mathcal{N}=2$
supersymmetry transformations is proposed. The field content is that of
$(2+1)$-gravity plus an $SU(2)$ gauge field, a spin-1/2 fermion charged with
respect to $SU(2)$ and a trivial free abelian gauge field. A peculiarity of the
model is the absence of gravitini, although it includes gravity and
supersymmetry. Likewise, no gauginos are present. All the parameters involved
in the system are either protected by gauge invariance or emerge as integration
constants. An effective mass and effective cosmological constant emerge by
spontaneus breaking of local scaling invariance. The vacuum sector is defined
by configurations with locally flat Lorentz and $SU(2)$ connections sporting
nontrivial global charges. Three-dimensional Lorentz-flat geometries are
spacetimes of locally constant negative --or zero--, Riemann curvature, which
include Minkowski space, AdS$_3$, BTZ black holes, and point particles. These
solutions admit different numbers of globally defined, covariantly constant
spinors and are therefore good candidates for stable ground states. The
fermionic sector in this system could describe the dynamics of electrons in
graphene in the long wavelength limit near the Dirac points, with the spin
degree of freedom of the electrons represented by the $SU(2)$ label. If this is
the case, the $SU(2)$ gauge field would produce a spin-spin interaction giving
rise to strong correlation of electron pairs.",1505.03834v1
2015-07-12,Lorentz Invariance Violation and IceCube Neutrino Events,"The IceCube neutrino spectrum shows a flux which falls of as $E^{-2}$ for sub
PeV energies but there are no neutrino events observed above $\sim 3$ PeV. In
particular the Glashow resonance expected at 6.3 PeV is not seen. We examine a
Planck scale Lorentz violation as a mechanism for explaining the cutoff of
observed neutrino energies around a few PeV. By choosing the one free parameter
the cutoff in neutrino energy can be chosen to be between 2 and 6.3 PeV. We
assume that neutrinos (antineutrinos) have a dispersion relation $E^2=p^2 -
(\xi_3/M_{Pl})~p^3$, and find that both $\pi^+$ and $\pi^-$ decays are
suppressed at neutrino energies of order of few PeV. We find that the $\mu^-$
decay being a two-neutrino process is enhanced, whereas $\mu^+$ decay is
suppressed. The $K^+\rightarrow \pi^0 e^+ \nu_e$ is also suppressed with a
cutoff neutrino energy of same order of magnitude, whereas $K^-\rightarrow
\pi^0 e^- \bar \nu_e$ is enhanced. The $n \rightarrow p^+ e^- \bar \nu_e$ decay
is suppressed (while the $\bar n \rightarrow p^- e^+ \nu_e$ is enhanced). This
means that the $\bar \nu_e$ expected from $n$ decay arising from $p+\gamma
\rightarrow \Delta \rightarrow \pi^+ n$ reaction will not be seen. This can
explain the lack of Glashow resonance events at IceCube. If no Glashow
resonance events are seen in the future then the Lorentz violation can be a
viable explanation for the IceCube observations at PeV energies.",1507.03193v2
2015-07-23,"Three arguable and interrelated concepts: point particle singularity, asymmetric action of EM on quantum wave functions, and the Left out restricted Lorentz gauge from U(1)","We address three issues. i. The point particle assumption, inherent to
non-quantum physics, is singular and entails divergent fields and integrals.
ii. In quantum physics EM plays an asymmetric roll. It acts on quantum wave
fields (wave functions) but the wave fields do not react back. We suggest to
promote the one sided action of EM on quantum fields into a mutual
action-reaction partnership. By so doing, the quantum wave shares its
analyticity with the EM field and removes the later's singularities and
divergences. iii) The conventional U(1) symmetry leaves quantum dynamics
invariant under a 'general' Lorentz gauge and impose the standard minimal
coupling of the quantum wave to the Em 4-vector potential. One, however, has
the option to ask for in-variance under the 'restricted' Lorentz gauge. This in
turn invites in a coupling to derivatives of the vector potential in addition
to the minimal coupling and, so to say, enlarges the U(1) symmetry. We find
that the electron exhibits distributed charge- and current- densities. The
enlarged symmetry is expected to bring in its own constant of motion. Indeed it
does. The anomalous g-factor of the so designed electron emerges, up to order
({\alpha}/{\pi})^2 as the new constant of motion but, without invoking the QED
formalism.",1507.06393v4
2015-08-26,Prospects On Testing Lorentz Invariance Violation With The Cherenkov Telescope Array,"The assumption of Lorentz invariance is one of the founding principles of
modern physics and violation of that would have deep consequences to our
understanding of the universe. Potential signatures of such a violation could
range from energy dependent dispersion introduced into a light curve to a
change in the photon-photon pair production threshold that changes the expected
opacity of the universe. Astronomical sources of Very High Energy (VHE) photons
can be used as test beams to probe fundamental physics phenomena, however, such
effects would likely be small and need to be disentangled from intrinsic source
physics processes. The Cherenkov Telescope Array (CTA) will be the next
generation ground based observatory of VHE photons. It will have improved flux
sensitivity, a lower energy threshold (tens of GeV), broader energy coverage
(nearly 5 decades) and improved energy resolution (better than 10\% over much
of the energy range) compared to current facilities in addition to excellent
time resolution for short timescale and rapidly varying phenomena. The expected
sensitivity of this facility leads to us to examine in this contribution the
kinds of limits to Lorentz Invariance Violation (LIV) that we could expect to
obtain on VHE observations of Active Galactic Nuclei (AGN), Gamma Ray Bursts
(GRBs) and pulsars with CTA. With a statistical sample and wide variety of
sources CTA has the potential to set model independent limits.",1508.06622v1
2016-02-03,External inverse-Compton emission from jetted tidal disruption events,"The recent discoveries of Swift J1644+57 and J2058+05 show that tidal
disruption events (TDEs) can launch relativistic jets. Super-Eddington
accretion produces a strong radiation field of order Eddington luminosity. In a
jetted TDE, electrons in the jet will inverse-Compton scatter the external
radiation field from the accretion disk and wind. Motivated by observations of
thermal optical-UV spectra in Swift J2058+05 and several other TDEs, we assume
the spectrum of the external radiation field intercepted by the relativistic
jet to be blackbody. Hot electrons in the jet scatter this thermal radiation
and produce luminosities 10^45-10^48 erg/s in the X/gamma-ray band.
  This model of thermal plus inverse-Compton radiation is applied to Swift
J2058+05. First, we show that the blackbody component in the optical-UV
spectrum most likely has its origin in the super-Eddington wind from the disk.
Then, using the observed blackbody component as the external radiation field,
we show that the X-ray luminosity and spectrum are consistent with the
inverse-Compton emission, under the following conditions: (1) the jet Lorentz
factor is ~5-10; (2) electrons in the jet have a powerlaw distribution with
minimum Lorentz factor ~1 and powerlaw index p = 2.4; (3) the wind is mildly
relativistic (Lorentz factor >~1.5) and has isotropic-equivalent mass-loss rate
~5 M_sun/yr. We describe the implications for jet composition and the radius
where jet energy is converted to radiation.",1602.01468v1
2016-02-22,Testing the equivalence principle and Lorentz invariance with PeV neutrinos from blazar flares,"It was recently proposed that a giant flare of the blazar PKS B1424-418 at
redshift $z=1.522$ is in association with a PeV-energy neutrino event detected
by IceCube. Based on this association we here suggest that the flight time
difference between the PeV neutrino and gamma-ray photons from blazar flares
can be used to constrain the violations of equivalence principle (EP) and the
Lorentz invariance for neutrinos. From the calculated Shapiro delay due to
clusters or superclusters in the nearby universe, we find that violation of the
equivalence principle for neutrinos and photons is constrained to an accuracy
of at least $10^{-5}$, which is two orders of magnitude tighter than the
constraint placed by MeV neutrinos from supernova 1987A. Lorentz invariance
violation (LIV) arises in various quantum-gravity theories, which predicts an
energy-dependent velocity of propagation in vacuum for photons and neutrinos.
We find that the association of the PeV neutrino with the gamma-ray outburst
set limits on the energy scale of possible LIV to $> 0.01 E_{pl}$ for linear
LIV models and $>6\times 10^{-8} E_{pl}$ for quadratic order LIV models, where
$E_{pl}$ is the Planck energy scale. These are the most stringent constraints
on neutrino LIV for subluminal neutrinos.",1602.06805v4
2016-03-09,Lorentz violations in multifractal spacetimes,"Using the recent observation of gravitational waves (GW) produced by a
black-hole merger, we place a lower bound on the energy above which a
multifractal spacetime would display an anomalous geometry and, in particular,
violations of Lorentz invariance. In the so-called multifractional theory with
$q$-derivatives, we show that the deformation of dispersion relations is much
stronger than in generic quantum-gravity approaches (including loop quantum
gravity) and, contrary to the latter, present observations on GWs can place
very strong bounds on the characteristic scales at which spacetime deviates
from standard Minkowski. The energy at which multifractal effects should become
apparent is $E_*>10^{14}\,{\rm GeV}$ (thus improving previous bounds by 12
orders of magnitude) when the exponents in the measure are fixed to their
central value $1/2$. We also estimate, for the first time, the effect of
logarithmic oscillations in the measure (corresponding to a discrete spacetime
structure) and find that they do not change much the bounds obtained in their
absence, unless the amplitude of the oscillations is fine tuned. This feature,
unavailable in known quantum-gravity scenarios, may help the theory to avoid
being ruled out by gamma-ray burst (GRB) observations, for which $E_*>
10^{17}\,{\rm GeV}$ or greater.",1603.03046v2
2016-03-11,The Magnetic Furnace: Intense Core Dynamos in B-stars,"The dynamo action achieved in the convective cores of main-sequence massive
stars is explored here through 3D global simulations of convective core dynamos
operating within a young $\Msun{10}$ B-type star, using the anelastic spherical
harmonic (ASH) code. These simulations capture the inner 65\% of this star by
radius, encompassing the convective nuclear-burning core (about 23\% by radius)
and a portion of the overlying radiative envelope. Eight rotation rates are
considered, ranging from 0.05\% to 16\% of the surface breakup velocity,
thereby capturing both convection that barely senses the effects of rotation
and other situations in which the Coriolis forces are prominent. The vigorous
dynamo action realized within all of these turbulent convective cores builds
magnetic fields with peak strengths exceeding a megagauss, with the overall
magnetic energy (ME) in the faster rotators reaching super-equipartition levels
compared to the convective kinetic energy (KE). The core convection typically
involves turbulent columnar velocity structures roughly aligned with the
rotation axis, with magnetic fields threading through these rolls and
possessing complex linkages throughout the core. The very strong fields are
able to coexist with the flows without quenching them through Lorentz forces.
The velocity and magnetic fields achieve such a state by being nearly
co-aligned, and with peak magnetic islands being somewhat displaced from the
fastest flows as the intricate evolution proceeds. As the rotation rate is
increased, the primary force balance shifts from nonlinear advection balancing
Lorentz forces to a magnetostrophic balance between Coriolis and Lorentz
forces.",1603.03659v2
2016-03-23,Circular orbits and related quasi-harmonic oscillatory motion of charged particles around weakly magnetized rotating black holes,"We study motion of charged particles in the field of a rotating black hole
immersed into an external asymptotically uniform magnetic field, focusing on
the epicyclic quasi-circular orbits near the equatorial plane. Separating the
circular orbits into four qualitatively different classes according to the sign
of the canonical angular momentum of the motion and the orientation of the
Lorentz force, we analyse the circular orbits using the so called force
formalism. We find the analytical solutions for the radial profiles of
velocity, specific angular momentum and specific energy of the circular orbits
in dependence on the black hole dimensionless spin and the magnetic field
strength. The innermost stable circular orbits are determined for all four
classes of the circular orbits. The stable circular orbits with outward
oriented Lorentz force can extend to radii lower than the radius of the
corresponding photon circular geodesic. We calculate the frequencies of the
harmonic oscillatory motion of the charged particles in the radial and vertical
directions related to the equatorial circular orbits and study the radial
profiles of the radial, $\omega_\mir$, vertical, $\omega_\mit$, and orbital,
$\omega_\mip$, frequencies, finding significant differences in comparison to
the epicyclic geodesic circular motion. The most important new phenomenon is
existence of toroidal charged particle epicyclic motion with $\omega_\mir \sim
\omega_{\mit} >> \omega_{\mip}$ that could occur around retrograde circular
orbits with outward oriented Lorentz force. We demonstrate that for the rapidly
rotating black holes the role of the 'Wald induced charge' can be relevant.",1603.07264v1
2016-03-30,Bimetric QED,"We study, as a model of Lorentz symmetry breaking, the quantisation and
renormalisation of an extension of QED in a flat spacetime where the photons
and electrons propagate differently and do not share the same lightcone. We
will refer to this model as Bimetric QED (BIMQED). As a preliminary we discuss
the formulation of electrodynamics in a pre-metric formalism showing
nevertheless that there is, on the basis of a simple criteron, a preferred
metric. Arising from this choice of metric is a Weyl-like tensor (WLT). The
Petrov classification of the WLT gives rise to a corresponding classification
of Lorentz symmetry breaking. We do not impose any constraint on the strength
of the symmetry breaking and are able to obtain explicit dispersion relations
for photon propagation in each of the Petrov classes. The associated
birefringence appears in some cases as two distinct polarisation dependent
lightcones and in other cases as a a more complicated structure that cannot be
disentangled in a simple way.
  We show how in BIMQED the renormalisation procedure can, in addition to its
effect on standard parameters such as charge and mass, force the
renormalisation of the metrics and the WLT. Two particularly tractable cases
are studied in detail for which we can obtain renormalisation group flows for
the parameters of the model together with an analysis of fixed point structure.
Of course these results are consistent with previous studies but we are not
constrained to treat Lorentz symmetry breaking as necessarily weak. As we found
in a previous study of a scalar field theory model an acceptable causal
structure for the model imposes constraints on relationship between the various
lightcones in BIMQED.",1603.09211v1
2016-04-07,Discovery of Weyl semimetal state violating Lorentz invariance in MoTe2,"A new type of Weyl semimetal state, in which the energy values of Weyl nodes
are not the local extrema, has been theoretically proposed recently, namely
type II Weyl semimetal. Distinguished from type I semimetal (e.g. TaAs), the
Fermi surfaces in a type II Weyl semimetal consist of a pair of electron and
hole pockets touching at the Weyl node. In addition, Weyl fermions in type II
Weyl semimetals violate Lorentz invariance. Due to these qualitative
differences distinct spectroscopy and magnetotransport properties are expected
in type II Weyl semimetals. Here, we present the direct observation of the
Fermi arc states in MoTe2 by using angle resolved photoemission spectroscopy.
Two arc states are identified for each pair of Weyl nodes whoes surface
projections of them possess single topological charge, which is a unique
property for type II Weyl semimetals. The experimentally determined Fermi arcs
are consistent with our first principle calculations. Our results unambiguously
establish that MoTe2 is a type II Weyl semimetal, which serves as a great test
bed to investigate the phenomena of new type of Weyl fermions with Lorentz
invariance violated.",1604.02116v1
2016-04-01,"On magnetic monopoles, the anomalous g-factor of the electron and the spin-orbit coupling in the Dirac theory","We discuss the algebra and the interpretation of the anomalous Zeeman effect
and the spin-orbit coupling within the Dirac theory. Whereas the algebra for
the anomalous Zeeman effect is impeccable and therefore in excellent agreement
with experiment, the physical interpretation of that algebra uses images that
are based on macroscopic intuition but do not correspond to the meaning of this
algebra. The interpretation violates the Lorentz symmetry. We give an
alternative intuitive description of the meaning of this effect, which respects
the symmetry and is exact. It can be summarized by stating that a magnetic
field makes any charged particle spin. We show also that the traditional
discussion about magnetic monopoles confuses two issues, viz. the symmetry of
the Maxwell equations and the quantization of charge. These two issues define
each a different concept of magnetic monopole. They cannot be merged together
into a unique all-encompassing issue. We also generalize the minimal
substitution for a charged particle, and provide some intuition for the
magnetic vector potential. We finally explore the algebra of the spin-orbit
coupling, which turns out to be badly wrong. The traditional theory that is
claimed to reproduce the Thomas half is based on a number of errors. An
error-free application of the Dirac theory cannot account for the Thomas
precession, because it only accounts for the instantaneous local boosts, not
for the rotational component of the Lorentz transformation. This runs contrary
to established beliefs, but Thomas precession can be understood in terms of the
Berry phase on a path through the velocity space of the Lorentz group manifold.
These results clearly reveal the limitations of the prevailing working
philosophy to ""shut up and calculate"".",1604.05160v1
2016-06-06,High harmonic interferometry of the Lorentz force in strong mid-infrared laser fields,"The interaction of intense mid-infrared laser fields with atoms and molecules
leads to a range of new opportunities, from the production of bright, coherent
radiation in the soft x-ray range to imaging molecular structures and dynamics
with attosecond temporal and sub-angstrom spatial resolution. However, all
these effects, which rely on laser-driven recollision of an electron removed by
the strong laser field and the parent ion, suffer from the rapidly increasing
role of the magnetic field component of the driving pulse: the associated
Lorentz force pushes the electrons off course in their excursion and suppresses
all recollision-based processes, including high harmonic generation, elastic
and inelastic scattering. Here we show how the use of two non-collinear beams
with opposite circular polarizations produces a forwards ellipticity which can
be used to monitor, control, and cancel the effect of the Lorentz force. This
arrangement can thus be used to re-enable recollision-based phenomena in
regimes beyond the long-wavelength breakdown of the dipole approximation, and
it can be used to observe this breakdown in high-harmonic generation using
currently-available light sources.",1606.01931v1
2016-07-01,Testing Lorentz symmetry with Lunar Laser Ranging,"Lorentz symmetry violations can be parametrized by an effective field theory
framework that contains both general relativity and the standard model of
particle physics called the standard-model extension (SME). We present new
constraints on pure gravity SME coefficients obtained by analyzing lunar laser
ranging (LLR) observations. We use a new numerical lunar ephemeris computed in
the SME framework and we perform a LLR data analysis using a set of 20721
normal points covering the period of August, 1969 to December, 2013. We
emphasize that linear combination of SME coefficients to which LLR data are
sensitive and not the same as those fitted in previous postfit residuals
analysis using LLR observations and based on theoretical grounds. We found no
evidence for Lorentz violation at the level of $10^{-8}$ for $\bar{s}^{TX}$,
$10^{-12}$ for $\bar{s}^{XY}$ and $\bar{s}^{XZ}$, $10^{-11}$ for
$\bar{s}^{XX}-\bar{s}^{YY}$ and
$\bar{s}^{XX}+\bar{s}^{YY}-2\bar{s}^{ZZ}-4.5\bar{s}^{YZ}$ and $10^{-9}$ for
$\bar{s}^{TY}+0.43\bar{s}^{TZ}$. We improve previous constraints on SME
coefficient by a factor up to 5 and 800 compared to postfit residuals analysis
of respectively binary pulsars and LLR observations.",1607.00294v3
2016-07-14,Protostring Scattering Amplitudes,"We calculate some tree level scattering amplitudes for a generalization of
the protostring, which is a novel string model implied by the simplest string
bit models. These bit models produce a lightcone worldsheet which supports $s$
integer moded Grassmann fields. In the generalization we supplement this
Grassmann worldsheet system with $d=24-s$ transverse coordinate worldsheet
fields. The protostring corresponds to $s=24$ and the bosonic string to $s=0$.
The interaction vertex is a simple overlap with no operator insertions at the
break/join point. Assuming that $s$ is even we calculate the multi-string
scattering amplitudes by bosonizing the Grassmann fields, each pair equivalent
to one compactified bosonic field, and applying Mandelstam's interacting string
formalism to a system of $s/2$ compactified and $d$ uncompactified bosonic
worldsheet fields. We obtain all amplitudes for open strings with no oscillator
excitations and for closed strings with no oscillator excitations and zero
winding number. We then study in detail some simple special cases. Multi-string
processes with maximal helicity violation have much simplified amplitudes. We
also specialize to general four string amplitudes and discuss their high energy
behavior. Most of these models are not covariant under the full Lorentz group
$O(d+1,1)$. The exceptions are the bosonic string whose Lorentz group is
$O(25,1)$ and the protostring whose Lorentz group is $O(1,1)$. The models in
between only enjoy an $O(1,1)\times O(d)$ spacetime symmetry.",1607.04237v1
2016-07-20,Entangled Harmonic Oscillators and Space-time Entanglement,"The mathematical basis for the Gaussian entanglement is discussed in detail,
as well as its implications in the internal space-time structure of
relativistic extended particles. It is shown that the Gaussian entanglement
shares the same set of mathematical formulas with the harmonic oscillator in
the Lorentz-covariant world. It is thus possible to transfer the concept of
entanglement to the Lorentz-covariant picture of the bound state which requires
both space and time separations between two constituent particles. These space
and time variables become entangled as the bound state moves with a
relativistic speed. It is shown also that our inability to measure the
time-separation variable leads to an entanglement entropy together with a rise
in the temperature of the bound state. As was noted by Paul A. M. Dirac in
1963, the system of two oscillators contains the symmetries of O(3,2) de Sitter
group containing two O(3,1) Lorentz groups as its subgroups. Dirac noted also
that the system contains the symmetry of the Sp(4) group which serves as the
basic language for two-mode squeezed states. Since the Sp(4) symmetry contains
both rotations and squeezes, one interesting case is the combination of
rotation and squeeze resulting in a shear. While the current literature is
mostly on the entanglement based on squeeze along the normal coordinates, the
shear transformation is an interesting future possibility. The mathematical
issues on this problem are clarified.",1607.05785v1
2016-09-01,Gamma-ray burst polarization reduction induced by the Lorentz invariance violation,"It has been observed that photons in the prompt emission of some gamma-ray
bursts (GRBs) are highly polarized. The high polarization is used by some
authors to give a strict constraint on the Lorentz invariance violation (LIV).
If the Lorentz invariance is broken, the polarization vector of a photon may
rotate during its propagation. The rotation angle of polarization vector
depends on both the photon energy and the distance of source. It is believed
that if high polarization is observed, then the relative rotation angle
(denoted by $\alpha$) of polarization vector of the highest energy photon with
respect to that of the lowest energy photon should be no more than $\pi/2$.
Otherwise, the net polarization will be severely suppressed, thus couldn't be
as high as what was actually observed. In this paper, we will give a detailed
calculation on the evolution of GRB polarization arising from LIV effect
duration the propagation. It is shown that the polarization degree rapidly
decrease as $\alpha$ increases, and reaches a local minimum at $\alpha\approx
\pi$, then increases until $\alpha\approx 3\pi/2$, after that decreases again
until $\alpha \approx 2\pi$, etc. The polarization degree as a function of
$\alpha$ oscillates with a quasi-period $T\approx \pi$, while the oscillating
amplitude gradually decreases to zero. Moreover, we find that a considerable
amount (more than $60\%$ of the initial polarization) of polarization degree
can be conserved when $\alpha\approx \pi/2$. The polarization observation in a
higher and wider energy band, a softer photon spectrum, and a higher redshift
GRB is favorable in order to tightly constrain LIV effect.",1609.00193v1
2016-09-09,An analogue of the Coleman-Mandula theorem for quantum field theory in curved spacetimes,"The Coleman-Mandula (CM) theorem states that the Poincar\'e and internal
symmetries of a Minkowski spacetime quantum field theory cannot combine
nontrivially in an extended symmetry group. We establish an analogous result
for quantum field theory in curved spacetimes, assuming local covariance, the
timeslice property, a local dynamical form of Lorentz invariance, and
additivity. Unlike the CM theorem, our result is valid in dimensions $n\ge 2$
and for free or interacting theories. It is formulated for theories defined on
a category of all globally hyperbolic spacetimes equipped with a global
coframe, on which the restricted Lorentz group acts, and makes use of a general
analysis of symmetries induced by the action of a group $G$ on the category of
spacetimes. Such symmetries are shown to be canonically associated with a
cohomology class in the second degree nonabelian cohomology of $G$ with
coefficients in the global gauge group of the theory. Our main result proves
that the cohomology class is trivial if $G$ is the universal cover $\cal S$ of
the restricted Lorentz group. Among other consequences, it follows that the
extended symmetry group is a direct product of the global gauge group and $\cal
S$, all fields transform in multiplets of $\cal S$, fields of different spin do
not mix under the extended group, and the occurrence of noninteger spin is
controlled by the centre of the global gauge group. The general analysis is
also applied to rigid scale covariance.",1609.02705v2
2017-02-22,Affine sphere relativity,"We investigate spacetimes whose light cones could be anisotropic. We prove
the equivalence of the structures: (a) Lorentz-Finsler manifold for which the
mean Cartan torsion vanishes, (b) Lorentz-Finsler manifold for which the
indicatrix (observer space) at each point is a convex hyperbolic affine sphere
centered on the zero section, and (c) pair given by a spacetime volume and a
sharp convex cone distribution. The equivalence suggests to describe {\em
(affine sphere) spacetimes} with this structure, so that no algebraic-metrical
concept enters the definition. As a result, this work shows how the metric
features of spacetime emerge from elementary concepts such as measure and
order. Non-relativistic spacetimes are obtained replacing proper spheres with
improper spheres, so the distinction does not call for group theoretical
elements. In physical terms, in affine sphere spacetimes the light cone
distribution and the spacetime measure determine the motion of massive and
massless particles (hence the dispersion relation). Furthermore, it is shown
that, more generally, for Lorentz-Finsler theories non-differentiable at the
cone, the lightlike geodesics and the transport of the particle momentum over
them are well defined though the curve parametrization could be undefined.
Causality theory is also well behaved. Several results for affine sphere
spacetimes are presented. Some results in Finsler geometry, for instance in the
characterization of Randers spaces, are also included.",1702.06739v1
2017-03-03,Spin orbit coupling and Lorentz force enhanced efficiency of TiO2 based dye sensitized solar cells,"We report on the effect of the strong spin orbit coupling and the Lorentz
force on the efficiency of TiO2 based dye sensitized solar cells. Upon
inclusion of Ho2O3, due to the strong spin orbit coupling of the rare earth
Ho3+ ion, we do see 13 percent enhancement in the efficiency. We attribute such
an enhancement in power conversion efficiency to the increased lifetime of the
photo-excited excitons. Essentially, a Ho3+ ion accelerates the phenomenon of
the spin rephasing or the intersystem crossing of the excitons in a
photosensitizer. Increase in the absorbance and decrease in the
photoluminescence intensity suggests a decrease in the recombination rate,
hinting an enhanced charge transport and is in accordance with our
electrochemical impedance spectra and the J V characteristics. From the above
we strongly believe that enhanced efficiency of the device is due to increased
intersystem crossing which would accelerate the exciton dissociation. On top of
spin orbit interaction, a configuration where the electric and magnetic fields
are perpendicular to each other helped in enhancing the efficiency by 16
percent, suggesting that the Lorentz force also plays a dominant role in
controlling the charge transport of the photo-generated charge carriers. We
strongly believe that this simple and novel strategy of improving the
efficiency may pave the way for realizing higher efficiency dye sensitized
solar cells.",1703.01099v1
2018-04-19,Scattering of a short electromagnetic pulse from a Lorentz-Duffing film: theoretical and numerical analysis,"We combine scattering theory, Fourier, traveling wave and asymptotic analyses
together with numerical simulations to present interesting and practically
useful properties of femtosecond pulse interaction with thin films. The
dispersive material is described by a single resonance Lorentz model and its
nonlinear extension with a cubic Duffing-type nonlinearity. A key feature of
the Lorentz dielectric function is that its real part becomes negative between
its zero and its pole, generating a forbidden region. We illustrate numerically
the linear interaction of the pulse with the film using both scattering theory
and Fourier analysis. Outside this region we show the generation of a sequence
of pulses separated by round trips in the Fabry-Perot cavity due to multiple
reflections. When the pulse spectrum is inside the forbidden region, we observe
total reflection. Near the pole of the dielectric function, we demonstrate the
slowing down of the pulse (group velocity tending to zero) in the medium that
behaves as a high-Q cavity. We use the combination of analysis and simulations
in the linear regime to validate the delta function approximation of the thin
layer; this collapses the forbidden region to a single resonant point of the
spectrum. We also study the single cycle pulse interaction with a thin film and
show three distinct types of reflection: half-pulse, sinusoidal wave train and
cosine wavelet. Finally we analyze the influence of a strong nonlinearity and
observe that the film switches from reflecting to trasparent.",1804.07061v1
2018-11-23,Lorentz covariance of the mass-polariton theory of light,"In the mass-polariton (MP) theory of light formulated by us recently [Phys.
Rev. A 95, 063850 (2017)], light in a medium is described as a coupled state of
the field and matter. The key result of the MP theory is that the optical force
of light propagating in a transparent material drives forward an atomic mass
density wave (MDW). In previous theories, it has been well understood that the
medium carries part of the momentum of light. The MP theory is fundamentally
different since it shows that this momentum is associated with the MDW that
carries a substantial atomic mass density and the related rest energy with
light. In this work, we prove the Lorentz covariance of the MP theory and show
how the stress-energy-momentum (SEM) tensor of the MP transforms between
arbitrary inertial frames. We also compare the MP SEM tensor with the
conventional Minkowski SEM tensor and show how the well-known fundamental
problems of the Minkowski SEM tensor become solved by the SEM tensor based on
the MP theory. We have particularly written our work for non-expert readers by
pointing out how the Lorentz transformation and various conservation laws and
symmetries of the special theory of relativity are fulfilled in the MP theory.",1811.09456v2
2018-11-18,Emergent photons and gravitons,"Now, it is already not a big surprise that due to the spontaneous Lorentz
invariance violation (SLIV) there may emerge massless vector and tensor
Goldstone modes identified particularly with photon and graviton. Point is,
however, that this mechanism is usually considered separately for photon and
graviton, though in reality they appear in fact together. In this connection,
we recently develop the common emergent electrogravity model which would like
to present here. This model incorporates the ordinary QED and tensor field
gravity mimicking linearized general relativity. The SLIV is induced by
length-fixing constraints put on the vector and tensor fields, $A_{\mu
}^{2}=\pm M_{A}^{2}$ and $H_{\mu \nu }^{2}=\pm M_{H}^{2}$ ($M_{A}$ and $M_{H}$
are the proposed symmetry breaking scales) which possess the much higher
symmetry then the model Lagrangian itself. As a result, the twelve Goldstone
modes are produced in total and they are collected into the vector and tensor
field multiplets. While photon is always the true vector Goldstone boson,
graviton contain pseudo-Goldstone modes as well. In terms of the appearing zero
modes, theory becomes essentially nonlinear and contains many Lorentz and CPT
violating interaction. However, as argued, they do not contribute in processes
which might lead to the physical Lorentz violation. Nonetheless, how the
emergent electrogravity theory could be observationally differed from
conventional QED and GR theories is also briefly discussed.",1811.09578v1
2019-05-01,New Methods for Conformal Correlation Functions,"The most general operator product expansion in conformal field theory is
obtained using the embedding space formalism and a new uplift for general
quasi-primary operators. The uplift introduced here, based on quasi-primary
operators with spinor indices only and standard projection operators, allows a
unified treatment of all quasi-primary operators irrespective of their Lorentz
group irreducible representations. This unified treatment works at the level of
the operator product expansion and hence applies to all correlation functions.
A very useful differential operator appearing in the operator product expansion
is established and its action on appropriate products of embedding space
coordinates is explicitly computed. This computation leads to tensorial
generalizations of the usual Exton function for all correlation functions.
Several important identities and contiguous relations are also demonstrated for
these new tensorial functions. From the operator product expansion all
correlation functions for all quasi-primary operators, irrespective of their
Lorentz group irreducible representations, can be computed recursively in a
systematic way. The resulting answer can be expressed in terms of tensor
structures that carry all the Lorentz group information and linear combinations
of the new tensorial functions. Finally, a summary of the well-defined rules
allowing the computation of all correlation functions constructively is
presented.",1905.00434v2
2019-05-13,Force balance in numerical geodynamo simulations: a systematic study,"Dynamo action in the Earth's outer core is expected to be controlled by a
balance between pressure, Coriolis, buoyancy and Lorentz forces, with marginal
contributions from inertia and viscous forces. Current numerical simulations of
the geodynamo, however, operate at much larger inertia and viscosity because of
computational limitations. This casts some doubt on the physical relevance of
these models. Our work aims at finding dynamo models in a moderate
computational regime which reproduce the leading-order force balance of the
Earth. By performing a systematic parameter space survey with Ekman numbers in
the range $10^{-6} \leq E \leq 10^{-4}$, we study the variations of the force
balance when changing the forcing (Rayleigh number, $Ra$) and the ratio between
viscous and magnetic diffusivities (magnetic Prandtl number, $Pm$). For
dipole-dominated dynamos, we observe that the force balance is structurally
robust throughout the investigated parameter space, exhibiting a
quasi-geostrophic (QG) balance (balance between Coriolis and pressure forces)
at zeroth order, followed by a first-order MAC balance between the ageostrophic
Coriolis, buoyancy and Lorentz forces. At second order this balance is
disturbed by contributions from inertia and viscous forces. Dynamos with a
different sequence of the forces, where inertia and/or viscosity replace the
Lorentz force in the first-order force balance, can only be found close to the
onset of dynamo action and in the multipolar regime. Our study illustrates that
most classical numerical dynamos are controlled by a QG-MAC balance, while
cases where viscosity and inertia play a dominant role are the exception rather
than the norm.",1905.04939v1
2020-07-02,Mechanical model of the inhomogeneous Maxwell's equations and of Lorentz transformations,"We present a mechanical model of a quasi-elastic body (aether) which
reproduces Maxwell's equations with charges and currents. Major criticism
against mechanical models of electrodynamics is that any presence of charges in
the known models appears to violate the continuity equation of the aether and
it remains a mystery as to where the aether goes and whence it comes. We
propose a solution to the mystery - in the present model the aether is always
conserved. Interestingly it turns out that the charge velocity coincides with
the aether velocity. In other words, the charges appear to be part of the
aether itself. We interpret the electric field as the flux of the aether and
the magnetic field as the torque per unit volume. In addition we show that the
model is consistent with the theory of relativity, provided that we use
Lorentz-Poincare interpretation (LPI) of relativity theory. We make a
statistical-mechanical interpretation of the Lorentz transformations. It turns
out that the length of a body is contracted by the electromagnetic field which
the molecules of this same body produce. This self-interaction causes also
delay of all the processes and clock-dilation results. We prove this by
investigating the probability distribution for a gas of self-interacting
particles. We can easily extend this analysis even to elementary particles.",2007.02004v5
2020-07-07,Edge modes of gravity -- II: Corner metric and Lorentz charges,"In this second paper of the series we continue to spell out a new program for
quantum gravity, grounded in the notion of corner symmetry algebra and its
representations. Here we focus on tetrad gravity and its corner symplectic
potential. We start by performing a detailed decomposition of the various
geometrical quantities appearing in BF theory and tetrad gravity. This provides
a new decomposition of the symplectic potential of BF theory and the simplicity
constraints. We then show that the dynamical variables of the tetrad gravity
corner phase space are the internal normal to the spacetime foliation, which is
conjugated to the boost generator, and the corner coframe field. This allows us
to derive several key results. First, we construct the corner Lorentz charges.
In addition to sphere diffeomorphisms, common to all formulations of gravity,
these charges add a local $\mathfrak{sl}(2,\mathbb{C})$ component to the corner
symmetry algebra of tetrad gravity. Second, we also reveal that the corner
metric satisfies a local $\mathfrak{sl}(2,\mathbb{R})$ algebra, whose Casimir
corresponds to the corner area element. Due to the space-like nature of the
corner metric, this Casimir belongs to the unitary discrete series, and its
spectrum is therefore quantized. This result, which reconciles discreteness of
the area spectrum with Lorentz invariance, is proven in the continuum and
without resorting to a bulk connection. Third, we show that the corner phase
space explains why the simplicity constraints become non-commutative on the
corner. This fact requires a reconciliation between the bulk and corner
symplectic structures, already in the classical continuum theory. Understanding
this leads inevitably to the introduction of edge modes.",2007.03563v1
2020-07-13,The radiatively corrected Kaluza-Klein masses in aether compactification,"We address the issue of radiative corrections to Kaluza-Klein (KK) masses in
five-dimensional QED supplemented by aether Lorentz-violating terms.
Specifically, we compute the corrections to the KK photon masses from one
fermion loop. In general, the KK masses receive radiative corrections due to
breaking the five-dimensional Lorentz invariance by compactification. As we
show, the presence of the additional Lorentz violating factor - an aether
background, leads to the non-trivial modification of these corrections. This
model may be of interest in addressing important phenomenological issues such
as the relation between radiative corrected KK mass splitting of a particular
mode and uncertainties in the measurements and/or possible spatial variation of
the fine-structure constant. For the recent data on the fine-structure
constant, we find a KK mass splitting of magnitude $\sim 0.01$ MeV for the
first excited Kaluza-Klein gauge boson at TeV scale. On the other hand, the
large KK modes limit displays a very interesting phenomenon, showing the very
special role of the aether in protecting the higher modes from the quantum
corrections.",2007.06683v1
2020-07-24,Bumblebee field in a Topological Framework,"A vector field coming from spontaneous Lorentz violation mechanism, namely
Bumblebee model is analysed in a topological framework in a $(1+2)D$ Minkowski
space-time. Taking a $(1+2)D$ nonlinear Bumblebee vector matter field dynamics
where we include topological like Chern-Simons type terms, a vector version of
a soliton state, or vortex was found. The Nielsen-Olesen procedure was used in
order to derive a Lorentz-violation vector parameter which characterizes, via
Spontaneous Symmetry Breaking mechanism, the non-trivial vacuum. We verify the
stability of the model as much as the magnetic vortex, and noticed that the
soliton modes with polarized direction generated can be associated with local
anisotropy of vacuum energy. The vortex equations of motion and the asymptotic
behaviour is presented. We have obtained that the effect of the Lorentz
symmetry violation expressed by the a time-like Bumblebee vector field vacuum
could be shown as kind of pulse at a fixed point $r_0$ in a limitless universe,
or as a barrier at $r_0$ which can represent a boundary in the universe, if the
Bumblebee vector field vacuum has space-like characteristic. We also analyse
the spectrum via propagators where we note that the topological mass
contributes as well to the dynamical mass poles. We obtain that the
Chern-Simons type terms, in fact, indicates the ""speed"" of the field to
saturate the asymptotic limit and that the vortex core can not be dimension
zero.",2007.12675v1
2010-05-05,Entanglement in Relativistic Quantum Mechanics,"In this thesis, entanglement under fully relativistic settings are discussed.
The thesis starts with a brief review of the relativistic quantum mechanics. In
order to describe the effects of Lorentz transformations on the entangled
states, quantum mechanics and special relativity are merged by construction of
the unitary irreducible representations of Poincar{\'e} group on the infinite
dimensional Hilbert space of state vectors. In this framework, the issue of
finding the unitary irreducible representations of Poincar{\'e} group is
reduced to that of the little group. Wigner rotation for the massive particles
plays a crucial role due to its effect on the spin polarization directions.
Furthermore, the physical requirements for constructing the correct
relativistic spin operator is also studied. Then, the entanglement and Bell
type inequalities are reviewed. Special attention has been devoted to two
historical papers, by EPR in 1935 and by J.S. Bell in 1964. The main part of
the thesis is based on the Lorentz transformation of the Bell states and the
Bell inequalities on these transformed states. It is shown that entanglement is
a Lorentz invariant quantity. That is, no inertial observer can see the
entangled state as a separable one. However, it was shown that the Bell
inequality may be satisfied for the Wigner angle dependent transformed
entangled states. Since the Wigner rotation changes the spin polarization
direction with the increased velocity, initial dichotomous operators can
satisfy the Bell inequality for those states. By choosing the dichotomous
operators taking into consideration the Wigner angle, it is always possible to
show that Bell type inequalities can be violated for the transformed entangled
states.",1005.0846v2
2010-05-21,Magnetic Tension of Sunspot Fine Structures,"The equilibrium structure of sunspots depends critically on its magnetic
topology and is dominated by magnetic forces. Tension force is one component of
the Lorentz force which balances the gradient of magnetic pressure in
force-free configurations. We employ the tension term of the Lorentz force to
clarify the structure of sunspot features like penumbral filaments, umbral
light bridges and outer penumbral fine structures. We compute vertical
component of tension term of Lorentz force over two active regions namely NOAA
AR 10933 and NOAA AR 10930 observed on 05 January 2007 and 12 December 2006
respectively. The former is a simple while latter is a complex active region
with highly sheared polarity inversion line (PIL). The vector magnetograms used
are obtained from Hinode(SOT/SP). We find an inhomogeneous distribution of
tension with both positive and negative signs in various features of the
sunspots. The existence of positive tension at locations of lower field
strength and higher inclination is compatible with the uncombed model of the
penumbral structure. Positive tension is also seen in umbral light bridges
which could be indication of uncombed structure of the light bridge. Likewise,
the upward directed tension associated with bipolar regions in the penumbra
could be a direct confirmation of the sea serpent model of penumbral
structures. Upward directed tension at the PIL of AR 10930 seems to be related
to flux emergence. The magnitude of the tension force is greater than the force
of gravity in some places, implying a nearly force-free configuration for these
sunspot features. From our study, magnetic tension emerges as a useful
diagnostic of the local equilibrium of the sunspot fine structures.",1005.3899v1
2010-05-21,Effects of Radiation-Reaction in Relativistic Laser Acceleration,"The goal of this paper is twofold: to explore the response of classical
charges to electromagnetic force at the level of unity in natural units and to
establish a criterion that determines physical parameters for which the related
radiation-reaction effects are detectable. In pursuit of this goal, the
Landau-Lifshitz equation is solved analytically for an arbitrary (transverse)
electromagnetic pulse. A comparative study of the radiation emission of an
electron in a linearly polarized pulse for the Landau-Lifshitz equation and for
the Lorentz force equation reveals the radiation-reaction dominated regime, in
which radiation-reaction effects overcome the influence of the external fields.
The case of a relativistic electron that is slowed down by a counter
propagating electromagnetic pulse is studied in detail. We further show that
when the electron experiences acceleration of order unity, the dynamics of the
Lorentz force equation, the Landau-Lifshitz equation and the
Lorentz-Abraham-Dirac equation all result in different radiation emission that
could be distinguished in experiment. Finally, our analytic and numerical
results are compared with those appearing in the literature.",1005.3980v3
2014-03-03,Photon and photino as Nambu-Goldstone zero modes in an emergent SUSY QED,"We argue that supersymmetry with its well known advantages, such as
naturalness, grand unification and dark matter candidate seems to possess one
more attractive feature: it may trigger, through its own spontaneous violation
in the visible sector, a dynamical generation of gauge fields as massless
Nambu-Goldstone modes during which physical Lorentz invariance itself is
ultimately preserved. We consider the supersymmetric QED model extended by an
arbitrary polynomial potential of massive vector superfield that breaks gauge
invariance in the SUSY invariant phase. However, the requirement of vacuum
stability in such class of models makes both supersymmetry and Lorentz
invariance to become spontaneously broken. As a consequence, massless photino
and photon appear as the corresponding Nambu-Goldstone zero modes in an
emergent SUSY QED, and also a special gauge invariance is simultaneously
generated. Due to this invariance all observable relativistically noninvariant
effects appear to be completely cancelled out among themselves and physical
Lorentz invariance is recovered. Nevertheless, such theories may have an
inevitable observational evidence in terms of the goldstino-photino like state
presented in the low-energy particle spectrum. Its study is of a special
interest for this class of SUSY models that, apart from some indication of an
emergence nature of QED and the Standard Model, may appreciably extend the
scope of SUSY breaking physics being actively studied in recent years.",1403.0436v2
2014-03-26,Quantum field theoretic properties of Lorentz-violating operators of nonrenormalizable dimension in the fermion sector,"In the current paper the properties of a quantum field theory based on
certain sets of Lorentz-violating coefficients in the nonminimal fermion sector
of the Standard-Model Extension are analyzed. In particular, three families of
coefficients are considered, where two of them are CPT-even and the third is
CPT-odd. As a first step the modified fermion dispersion relations are
obtained. Then the positive- and negative-energy solutions of the modified
Dirac equation and the fermion propagator are derived. These are used to
demonstrate the validity of the optical theorem at tree-level, which provides a
cross-check for the results obtained. Furthermore unitarity is examined and
seems to be valid for the first set of CPT-even coefficients. However for the
remaining sets certain issues with unitarity are found. The article
demonstrates that the adapted quantum field theoretical methods at tree-level
work for the nonminimal, Lorentz-violating framework considered. Besides, the
quantum field theory based on the first family of CPT-even coefficients is most
likely well-behaved at lowest order perturbation theory. The results are
important for future phenomenological investigations carried out in the context
of field theory, e.g., the computation of decay rates and cross sections at
tree-level.",1403.6766v2
2016-11-14,Local effects of the quantum vacuum in Lorentz-violating electrodynamics,"The Casimir effect is one of the most remarkable consequences of the non-zero
vacuum energy predicted by quantum field theory. In this paper we use a local
approach to study the Lorentz violation effects of the minimal standard model
extension on the Casimir force between two parallel conducting plates in the
vacuum. Using a perturbative method similar to that used for obtaining the Born
series for the scattering amplitudes in quantum mechanics, we compute, at
leading order in the Lorentz-violating coefficients, the relevant Green's
function which satisfies given boundary conditions. The standard
point-splitting technique allow us to express the vacuum expectation value of
the stress-energy tensor in terms of the Green's function. We discuss its
structure in the region between the plates. We compute the renormalized vacuum
stress, which is obtained as the difference between the vacuum stress in the
presence of the plates and that of the vacuum. The Casimir force is evaluated
in an analytical fashion by two methods: by differentiating the renormalized
global energy density and by computing the normal-normal component of the
renormalized vacuum stress. We compute the local Casimir energy, which is found
to diverge as approaching the plates, and we demonstrate that it does not
contribute to the observable force.",1611.04616v1
2016-12-31,Energy Scale of Lorentz Violation in Rainbow Gravity,"We modify the standard relativistic dispersion relation in a way which breaks
Lorentz symmetry - the effect is predicted in a high-energy regime of some
modern theories of quantum gravity. We show that it is possible to realise this
scenario within the framework of Rainbow Gravity which introduces two new
energy-dependent functions $f_1(E)$ and $f_2(E)$ into the dispersion relation.
Additionally, we assume that the gravitational constant $G$ and the
cosmological constant $\Lambda$ also depend on energy $E$ and introduce the
scaling function $h(E)$ in order to express this dependence. For cosmological
applications we specify the functions $f_1$ and $f_2$ in order to fit massless
particles which allows us to derive modified cosmological equations. Finally,
by using Hubble+SNIa+BAO(BOSS+Lyman $\alpha$)+CMB data, we constrain the energy
scale $E_{LV}$ to be at least of the order of $10^{16}$ GeV at $1\sigma$ which
is the GUT scale or even higher $10^{17}$ GeV at $3\sigma$. Our claim is that
this energy can be interpreted as the decoupling scale of massless particles
from spacetime Lorentz violating effects.",1701.00533v4
2017-04-08,Dissipative Quantum Electromagnetics,"The dissipative quantum electromagnetics is introduced in a comprehensive
manner as a field-matter-bath coupling problem. First, the matter is described
by a cluster of Lorentz oscillators. Then the Maxwellian free field is coupled
to the Lorentz oscillators to describe a frequency dispersive medium. The
classical Hamiltonian is derived for such a coupled system, using Lorenz gauge
and decoupled scalar and vector potential formulations. The classical equations
of motion are derivable from the Hamiltonian using Hamilton equations. Then the
Hamiltonian is quantized with all the pertinent variables with the introduction
of commutators between the variables and their conjugate pairs. The quantum
equations of motion can be derived using the quantum Hamilton equations. It can
be shown that such a quantization scheme preserves the quantum commutators
introduced. Then a noise bath consisting of simple harmonic oscillators is
introduced and coupled to the matter consisting of Lorentz oscillators to
induce quantum loss. Langevin source emerges naturally in such a procedure, and
it can be shown that the results are consistent with the fluctuation
dissipation theorem, and the quantization procedure of Welsch's group. The
advantage of the present procedure is that no diagonalization of the
Hamiltonian is necessary to arrive at the quantum equations of motion. Finally,
we apply the quantization scheme to model spontaneous emission of a two-level
polarized atom placed above a dielectric cylinder that supports a bound state
in the continuum.",1704.02448v4
2017-04-13,Reformulation of the symmetries of first-order general relativity,"We report a new internal gauge symmetry of the n-dimensional Palatini action
with cosmological term (n>3) that is the generalization of three-dimensional
local translations. This symmetry is obtained through the direct application of
the converse of Noether's second theorem on the theory under consideration. We
show that diffeomorphisms can be expressed as linear combinations of it and
local Lorentz transformations with field-dependent parameters up to terms
involving the variational derivatives of the action. As a result, the new
internal symmetry together with local Lorentz transformations can be adopted as
the fundamental gauge symmetries of general relativity. Although their gauge
algebra is open in general, it allows us to recover, without resorting to the
equations of motion, the very well-known Lie algebra satisfied by translations
and Lorentz transformations in three dimensions. We also report the analog of
the new gauge symmetry for the Holst action with cosmological term, finding
that it explicitly depends on the Immirzi parameter. The same result concerning
its relation to diffeomorphisms and the open character of the gauge algebra
also hold in this case. Finally, we consider the non-minimal coupling of a
scalar field to gravity in n dimensions and establish that the new gauge
symmetry is affected by this matter field. Our results indicate that general
relativity in dimension greater than three can be thought of as a gauge theory.",1704.04248v2
2009-12-16,Gauge invariant non-linear electrodynamics motivated by a spontaneous breaking of the Lorentz symmetry,"We introduce a new version of non-linear electrodynamics which is produced by
a spontaneous symmetry breaking of Lorentz invariance induced by the non-zero
expectation value of the electromagnetic field strength. The symmetry breaking
potential is argued to effectively arise from the integration of massive gauge
bosons and fermions in an underlying fundamental theory. All possible choices
of the vacuum lead only to the remaining invariant subgroups T(2) and HOM(2).
We explore the plane wave solutions of the linearized sector of the model for
an arbitrary vacuum. They present two types of dispersion relations. One
corresponds to the case of the usual Maxwell electrodynamics with the standard
polarization properties of the fields. The other dispersion relation involves
anisotropies determined by the structure of the vacuum. The model is stable in
the small Lorentz invariance violation approximation. We have embedded our
model in the photon sector of the Standard Model Extension in order to set
bounds for our parameters. The one-way anisotropic speed of light is calculated
for a general vacuum and its isotropic component is strongly bounded by
${\tilde \delta c}/c < 2 \times 10^{-32}$. The anisotropic violation
contribution is estimated by introducing an alternative definition for the
difference of the two-way speed of light in perpendicular directions $\Delta
c$, which is also strongly bounded by ${\Delta c}/c < 10^{-32}$. Finally, we
speculate on the relation of the vacuum energy of the model with the
cosmological constant and propose a connection between the vacuum fields and
the intergalactic magnetic fields.",0912.3053v1
2009-12-28,Electrodynamics of balanced charges,"In this work we modify the wave-corpuscle mechanics for elementary charges
introduced by us recently. This modification is designed to better describe
electromagnetic (EM) phenomena at atomic scales. It includes a modification of
the concept of the classical EM field and a new model for the elementary charge
which we call a balanced charge (b-charge). A b-charge does not interact with
itself electromagnetically, and every b-charge possesses its own elementary EM
field. The EM energy is naturally partitioned as the interaction energy between
pairs of different b-charges. We construct EM theory of b-charges (BEM) based
on a relativistic Lagrangian with the following properties: (i) b-charges
interact only through their elementary EM potentials and fields; (ii) the field
equations for the elementary EM fields are exactly the Maxwell equations with
proper currents; (iii) a free charge moves uniformly preserving up to the
Lorentz contraction its shape; (iv) the Newton equations with the Lorentz
forces hold approximately when charges are well separated and move with
non-relativistic velocities. The BEM theory can be characterized as
neoclassical one which covers the macroscopic as well as the atomic spatial
scales, it describes EM phenomena at atomic scale differently than the
classical EM theory. It yields in macroscopic regimes the Newton equations with
Lorentz forces for centers of well separated charges moving with
nonrelativistic velocities. Applied to atomic scales it yields a hydrogen atom
model with a frequency spectrum matching the same for the Schrodinger model
with any desired accuracy.",0912.5143v2
2011-11-02,Particle acceleration in the polar cap region of an oscillating neutron star,"We revisit particle acceleration in the polar cap region of a neutron star by
taking into account both general relativistic effects and the presence of
toroidal oscillations at the star surface. In particular, we address the
question of whether toroidal oscillations at the stellar surface can affect the
acceleration properties in the polar cap. We solve numerically the relativistic
electrodynamics equations in the stationary regime, focusing on the computation
of the Lorentz factor of a space-charge-limited electron flow accelerated in
the polar cap region of a rotating and oscillating pulsar. To this extent, we
adopt the correct expression of the general relativistic Goldreich-Julian
charge density in the presence of toroidal oscillations. Depending on the ratio
of the actual charge density of the pulsar magnetosphere to the
Goldreich-Julian charge density, we distinguish two different regimes of the
Lorentz factor of the particle flow, namely an oscillatory regime produced for
sub-GJ current density configurations, which does not produce an efficient
acceleration, and a true accelerating regime for super-GJ current density
configurations. We find that star oscillations may be responsible for a
significant asymmetry in the pulse profile that depends on the orientation of
the oscillations with respect to the pulsar magnetic field. In particular,
significant enhancements of the Lorentz factor are produced by stellar
oscillations in the super-GJ current density regime.",1111.0563v3
2011-11-17,Analysis of the consistency of parity-odd nonbirefringent modified Maxwell theory,"There exist two deformations of standard electrodynamics that describe
Lorentz symmetry violation in the photon sector: CPT-odd Maxwell-Chern-Simons
theory and CPT-even modified Maxwell theory. In this article, we focus on the
parity-odd nonbirefringent sector of modified Maxwell theory. It is coupled to
a standard Dirac theory of massive spin-1/2 fermions resulting in a modified
quantum electrodynamics (QED). This theory is discussed with respect to
properties such as microcausality and unitarity, where it turns out that these
hold. Furthermore, a priori, the limit of the theory for vanishing
Lorentz-violating parameters seems to be discontinuous. Since it is not clear,
whether this is a gauge artifact, the cross section for a physical process -
modified Compton scattering - is calculated numerically. Despite the numerical
instabilities occurring for scattering of unpolarized electrons off polarized
photons in the second physical polarization state, it is shown that for
Lorentz-violating parameters much smaller than 1 the modified theory approaches
standard QED, which is strengthened by analytical investigations. Hence, the
theory proves to be consistent, at least with regard to the investigations
performed. This leads to the interesting result of having a well-defined
parity-odd extension of QED.",1111.4182v3
2011-11-21,The non-thermal emission of extended radio galaxy lobes with curved electron spectra,"The existing theoretical framework for the energies stored in the
synchrotron-emitting lobes of radio galaxies and quasars doesn't properly
account for the curved spectral shape that many of them exhibit. We
characterise these spectra using parameters that are straightforwardly
observable in the era of high-resolution, low-frequency radio astronomy: the
spectral curvature and the turnover in the frequency spectrum. This
characterisation gives the Lorentz factor at the turnover in the energy
distribution (we point out that this is distinctly different from the Lorentz
factor corresponding to the turnover frequency in a way that depends on the
amount of curvature in the spectrum) and readily gives the equipartition
magnetic field strength and the total energy of the radiating plasma obviating
the need for any assumed values of the cutoff frequencies to calculate these
important physical quantities. This framework readily yields the form of the
X-ray emission due to inverse-Compton (IC) scattering of Cosmic Microwave
Background (CMB) photons by the electrons in the plasma having Lorentz factors
of $\sim$1000. We also present the contribution to CMB anisotropies due to
relativistic plasmas such as giant radio galaxy lobes, expressed in terms of
the extent to which the lobes have their magnetic field and particle energies
are in equipartition with one another.",1111.4878v1
2011-11-21,The Superluminal Neutrinos from Deformed Lorentz Invariance,"We study two superluminal neutrino scenarios where \delta v\equiv (v-c)/c is
a constant. To be consistent with the OPERA, Borexino, and ICARUS experiments
and with the SN1987a observations, we assume that \delta v_{\nu} on the Earth
is about three order larger than that on the interstellar scale. To explain the
theoretical challenges from the Bremsstrahlung effects and pion decays, we
consider the deformed Lorentz invariance, and show that the superluminal
neutrino dispersion relations can be realized properly while the modifications
to the dispersion relations of the other Standard Model particles can be
negligible. In addition, we propose the deformed energy and momentum
conservation laws for a generic physical process. In Scenario I the momentum
conservation law is preserved while the energy conservation law is deformed. In
Scenario II the energy conservation law is preserved while the momentum
conservation law is deformed. We present the energy and momentum conservation
laws in terms of neutrino momentum in Scenario I and in terms of neutrino
energy in Scenario II. In such formats, the energy and momentum conservation
laws are exactly the same as those in the traditional quantum field theory with
Lorentz symmetry. Thus, all the above theoretical challenges can be
automatically solved. We show explicitly that the Bremsstrahlung processes are
forbidden and there is no problem for pion decays.",1111.4994v3
2011-11-28,Lorentz violating kinematics: Threshold theorems,"Recent tentative experimental indications, and the subsequent theoretical
speculations, regarding possible violations of Lorentz invariance have
attracted a vast amount of attention. An important technical issue that
considerably complicates detailed calculations in any such scenario, is that
once one violates Lorentz invariance the analysis of thresholds in both
scattering and decay processes becomes extremely subtle, with many new and
naively unexpected effects. In the current article we develop several extremely
general threshold theorems that depend only on the existence of some energy
momentum relation E(p), eschewing even assumptions of isotropy or monotonicity.
We shall argue that there are physically interesting situations where such a
level of generality is called for, and that existing (partial) results in the
literature make unnecessary technical assumptions. Even in this most general of
settings, we show that at threshold all final state particles move with the
same 3-velocity, while initial state particles must have 3-velocities
parallel/anti-parallel to the final state particles. In contrast the various
3-momenta can behave in a complicated and counter-intuitive manner.",1111.6340v2
2012-01-25,Mach like principle from conserved charges,"We study models where the gauge coupling constants, masses and the
gravitational constant are functions of some conserved charge in the universe,
and furthermore a cosmological constant that depends on the total charge of the
universe. We first consider the standard Dirac action, but where the mass and
the electromagnetic coupling constant are a function of the charge in the
universe and afterwards extend this to curved spacetime and consider gauge
coupling constants, the gravitation constant and the mass as a function of the
charge of the universe, which represent a sort of Mach principle for all the
constants of nature. In the flat space formulation, the formalism is not
manifestly Lorentz invariant, however Lorentz invariance can be restored by
performing a phase transformation of the Dirac field, while in the curved space
time formulation, there is the additional feature that some of the equations of
motion break the general coordinate invariance also, but in a way that can be
understood as a coordinate choice only, so the equations are still of the
General Relativity type, but with a certain natural coordinate choice, where
there is no current of the charge. We have generalized what we have done and
also constructed a cosmological constant which depends on the total charge of
the universe. If we were to use some only approximately conserved charge for
these constructions, like say baryon number (in the context of the standard
model), this will lead to corresponding violations of Lorentz symmetry in the
early universe for example. The construction of charge dependent contributions
can also be motivated from the structure of the ""infra-red counter terms""
needed to cancel infra red divergences for example in three dimensions.",1201.5257v1
2012-04-19,"The Lorentz transformations of the vectors E, B, P, M and the external electric fields from a stationary superconducting wire with a steady current and from a stationary permanent magnet","In the first part of this paper we review the fundamental difference between
the usual transformations of the three-dimensional (3D) vectors of the electric
field $\mathbf{E}$, the magnetic field $\mathbf{B}$, the polarization
$\mathbf{P}$, the magnetization $\mathbf{M}$ and the Lorentz transformations of
the 4D geometric quantities, vectors E, B, P, M, with many additional
explanations and several new results. In the second part, we have discussed the
existence of the electric field vector E outside a stationary superconducting
wire with a steady current and also different experiments for the detection of
such electric fields. Furthermore, a fundamental prediction of the existence of
the external electric field vector E from a stationary permanent magnet is
considered. These electric fields are used for the resolution of the
""charge-magnet paradox"" with 4D geometric quantities for a qualitative
explanation of the Aharonov-Bohm effect in terms of fields and not, as usual,
in terms of the vector potential and for a qualitative explanation that the
particle interference is not a test of a Lorentz-violating model of
electrodynamics according to which a magnetic solenoid generates not only a
static magnetic field but also a static electric field.",1204.5137v4
2013-09-18,Inflationary Instabilities of Einstein-Aether Cosmology,"We examine the consequences of Lorentz violation during slow-roll inflation.
We consider a canonical scalar inflaton coupled, through its potential, to the
divergence of a fixed-norm timelike vector field, or ""aether."" The vector is
described by Einstein-aether theory, a vector-tensor model of gravitational
Lorentz violation. We derive and analyze the cosmological perturbation
equations for the metric, inflaton, and aether. If the scale of Lorentz
violation is sufficiently small compared to the Planck mass, and the strength
of the scalar-aether coupling is suitably large, then the spin-0 and spin-1
perturbations grow exponentially and spoil the inflationary background. The
effects of such a coupling on the CMB are too small to be visible to current or
near-future CMB experiments; unusually, no isocurvature modes are produced at
first order in a perturbative expansion around the aether norm. These results
are discussed for both a general potential and a worked example, $m^2 \phi^2$
inflation with a quadratic scalar-aether coupling term.",1309.4778v2
2013-09-24,Mechanical design and analysis for a low beta squeezed half-wave resonator,"A superconducting half-wave resonator (HWR) of frequency=162.5 MHz and
{\beta}=0.09 has been developed at Institute of Modern Physics. Mechanical
stability of the low beta HWR cavity is a big challenge in cavity design and
optimization. The mechanical deformations of a radio frequency superconducting
cavity could be a source of instability, both in continues wave(CW) operation
or in pulsed mode. Generally, the lower beta cavities have stronger Lorentz
force detuning than that of the higher beta cavities. In this paper, a basic
design consideration in the stiffening structure for the detuning effect caused
by helium pressure and Lorentz force has been presented. The mechanical modal
analysis has been investigated with finite element method(FEM). Based on these
considerations, a new stiffening structure has been promoted for the HWR
cavity. The computation results concerning the frequency shift show that the
low beta HWR cavity with new stiffening structure has low frequency sensitivity
coefficient, Lorentz force detuning coefficient KL and stable mechanical
property.",1309.6035v1
2013-09-30,Why the length of a quantum string cannot be Lorentz contracted,"We propose a quantum gravity-extended form of the classical length
contraction law obtained in Special Relativity. More specifically, the
framework of our discussion is the UV self-complete theory of quantum gravity.
Against this background, we show how our results are consistent with, i) the
generalised form of the Uncertainty Principle (GUP), ii) the so called
hoop-conjecture which we interpret, presently, as the saturation of a Lorentz
boost by the formation of a black hole in a two-body scattering, and iii) the
intriguing notion of ""classicalization"" of trans-Planckian physics. Pushing
these ideas to their logical conclusion, we argue that there is a physical
limit to the Lorentz contraction rule in the form of some minimal universal
length determined by quantum gravity, say the Planck Length, or any of its
current embodiments such as the string length, or the TeV quantum gravity
length scale. In the latter case, we determine the \emph{critical boost} that
separates the ordinary ""particle phase,"" characterized by the Compton
wavelength, from the ""black hole phase"", characterized by the effective
Schwarzschild radius of the colliding system. Finally, with the
""classicalization"" of quantum gravity in mind, we comment on the remarkable
identity, to our knowledge never noticed before, between three seemingly
independent universal quantities, namely, a) the ""string tension"", b) the
""linear energy density,"" or \emph{tension} that exists at the core of all
Schwarzschild black holes, and c) the ""superforce"" i.e., the Planckian limit of
the static electro-gravitational force and, presumably, the unification point
of all fundamental forces.",1309.7741v1
2015-12-16,Anisotropic Hardy-Lorentz Spaces and Their Applications,"Let $p\in(0,1]$, $q\in(0,\infty]$ and $A$ be a general expansive matrix on
$\mathbb{R}^n$. The authors introduce the anisotropic Hardy-Lorentz space
$H^{p,q}_A(\mathbb{R}^n)$ associated with $A$ via the non-tangential grand
maximal function and then establish its various real-variable characterizations
in terms of the atomic or the molecular decompositions, the radial or the
non-tangential maximal functions, or the finite atomic decompositions. All
these characterizations except the $\infty$-atomic characterization are new
even for the classical isotropic Hardy-Lorentz spaces on $\mathbb{R}^n$. As
applications, the authors first prove that $H^{p,q}_A(\mathbb{R}^n)$ is an
intermediate space between $H^{p_1,q_1}_A(\mathbb{R}^n)$ and
$H^{p_2,q_2}_A(\mathbb{R}^n)$ with $0<p_1<p<p_2<\infty$ and
$q_1,\,q,\,q_2\in(0,\infty]$, and also between $H^{p,q_1}_A(\mathbb{R}^n)$ and
$H^{p,q_2}_A(\mathbb{R}^n)$ with $p\in(0,\infty)$ and $0<q_1<q<q_2\leq\infty$
in the real method of interpolation. The authors then establish a criterion on
the boundedness of sublinear operators from $H^{p,q}_A(\mathbb{R}^n)$ into a
quasi-Banach space; moreover, the authors obtain the boundedness of
$\delta$-type Calder\'{o}n-Zygmund operators from $H^p_A(\mathbb{R}^n)$ to the
weak Lebesgue space $L^{p,\infty}(\mathbb{R}^n)$ (or
$H^{p,\infty}_A(\mathbb{R}^n)$) in the critical case, from
$H_A^{p,q}(\mathbb{R}^n)$ to $L^{p,q}(\mathbb{R}^n)$ (or
$H_A^{p,q}(\mathbb{R}^n)$) with $\delta\in(0,\frac{\ln\lambda_-}{\ln b}]$,
$p\in(\frac1{1+\delta},1]$ and $q\in(0,\infty]$, as well as the boundedness of
some Calder\'{o}n-Zygmund operators from $H_A^{p,q}(\mathbb{R}^n)$ to
$L^{p,\infty}(\mathbb{R}^n)$, where $b:=|\det A|$,
$\lambda_-:=\min\{|\lambda|:\ \lambda\in\sigma(A)\}$ and $\sigma(A)$ denotes
the set of all eigenvalues of $A$.",1512.05081v1
2016-05-27,A spectre is haunting the cosmos: Quantum stability of massive gravity with ghosts,"Many theories of modified gravity with higher order derivatives are usually
ignored because of serious problems that appear due to an additional ghost
degree of freedom. Most dangerously, it causes an immediate decay of the
vacuum. However, breaking Lorentz invariance can cure such abominable behavior.
By analyzing a model that describes a massive graviton together with a
remaining Boulware-Deser ghost mode we show that even ghostly theories of
modified gravity can yield models that are viable at both classical and quantum
levels and, therefore, they should not generally be ruled out. Furthermore, we
identify the most dangerous quantum scattering process that has the main impact
on the decay time and find differences to simple theories that only describe an
ordinary scalar field and a ghost. Additionally, constraints on the parameters
of the theory including some upper bounds on the Lorentz-breaking cutoff scale
are presented. In particular, for a simple theory of massive gravity we find
that a breaking of Lorentz invariance is allowed to happen even at scales above
the Planck mass. Finally, we discuss the relevance to other theories of
modified gravity.",1605.08757v4
2016-12-03,Disproof of a widely-accepted mathematical conjecture,"A mathematical conjecture is successfully identified, which is used for
relativistic analysis of dielectric Einstein-box thought experiment in a Letter
(Ramos, Rubilar, and Obukhov, Phys. Lett. A 375, 1703 (2011)), where the
authors conjecture (without any citations) that, the symmetry and
divergence-less property of a Lorentz 4-tensor is a sufficient condition for
the time-column space integrals to constitute a Lorentz 4-vector. This
mathematical conjecture has been thought to be ""a mathematical fact the
validity of which was shown well"" in textbooks. However in this paper, we
indicate that this conjecture has never been proved mathematically. By
enumerating a counterexample, we find that this mathematical conjecture is
flawed, and it is not persuasive to use a flawed mathematical conjecture as a
starting point to resolve Abraham-Minkowski controversy over light momentum in
a dielectric medium. We also indicate that this flawed mathematical conjecture
is actually a widely-accepted conjecture in the dynamics of relativity in
textbooks for many decades. To eliminate a misunderstanding of this flawed
conjecture in the community, we provide a detailed elucidation of why
M{\o}ller's mathematical statement, also called ""M{\o}ller's version of von
Laue's theorem"", only defines a trivial zero 4-vector for an electromagnetic
stress-energy Lorentz 4-tensor.",1612.03201v4
2016-12-21,Lorentz-symmetry test at Planck-scale suppression with nucleons in a spin-polarized $^{133}$Cs cold atom clock,"We introduce an improved model that links the frequency shift of the
$^{133}\text{Cs}$ hyperfine Zeeman transitions $\vert F = 3, m_F>
\longleftrightarrow \vert F = 4, m_F >$ to the Lorentz-violating Standard-Model
Extension (SME) coefficients of the proton and neutron. The new model uses
Lorentz transformations developed to second order in boost and additionally
takes the nuclear structure into account, beyond the simple Schmidt model used
previously in SME analyses, thereby providing access to both proton and neutron
SME coefficients including the isotropic coefficient $\tilde{c}_{TT}$. Using
this new model in a second analysis of the data delivered by the FO2 dual Cs/Rb
fountain at Paris Observatory and previously analysed in
arXiv:hep-ph/0601024v1, we improve by up to 12 orders of magnitude the present
maximum sensitivities (see arXiv:0801.0287v9) on the $\tilde{c}_{Q}$,
$\tilde{c}_{TJ}$ and $\tilde{c}_{TT}$ coefficients for the neutron and on the
$\tilde{c}_{TT}$ coefficient for the proton, reaching respectively $10^{-20}$,
$10^{-17}$, $10^{-13}$ and $10^{-15}$ GeV.",1612.07390v2
2017-06-01,Relativistic Time Dilation and Length Contraction in Discrete Space-Time using a Modified Distance Formula,"In this work, the relativistic phenomena of Lorentz contraction and time
dilation are derived using a modified distance formula appropriate for discrete
space. This new distance formula is different than Pythagoras's theorem but
converges to it for distances large relative to the Planck length. First, four
candidate formulas developed by different people over the last 70 years will be
considered. Three of the formulas are shown to be identical for conditions that
best describe discrete space; this equation is then used in the rest of the
paper. It is shown that this new distance formula is applicable to all
size-scales, from the Planck length upwards, and solves two major historical
problems associated with a discrete space-time model. One problem it solves is
maintaining isotropy in discrete space. The second problem it solves is the
commonly perceived incompatibility of the model's concept of an immutable
""atom"" of space and the Lorentz contraction of this atom required by special
relativity. With the new distance formula, it is shown that the Lorentz
contraction of the atom of space does not occur regardless of the relative
velocities of two reference frames. It is also shown that time dilation of the
atom of time does not occur. Also discussed is the possibility of any object
being able to travel at the speed of light for specific temporal durations
derived in this work.",1706.00693v2
2017-06-05,The Bright and the Slow -- GRBs 100724B \& 160509A with high-energy cutoffs at $\lesssim100\;$MeV,"We analyze the prompt emission of GRB 100724B and GRB 160509A, two of the
brightest Gamma-Ray Bursts (GRBs) observed by Fermi at $\lesssim{\rm MeV}$
energies but surprisingly faint at $\gtrsim100\;$MeV energies. Time-resolved
spectroscopy reveals a sharp high-energy cutoff at energies $E_c\sim20-60\;$MeV
for GRB~100724B and $E_c\sim80-150\;$MeV for GRB~160509A. We first characterize
phenomenologically the cutoff and its time evolution. We then fit the data to
two models where the high-energy cutoff arises from intrinsic opacity to pair
production within the source ($\tau_{\gamma\gamma}$): (i) a Band spectrum with
$\tau_{\gamma\gamma}$ from the internal-shocks motivated model of Granot et al.
(2008), and (ii) the photospheric model of Gill & Thompson (2014). Alternative
explanations for the cutoff, such as an intrinsic cutoff in the emitting
electron energy distribution, appear to be less natural. Both models provide a
good fit to the data with very reasonable physical parameters, providing a
direct estimate of bulk Lorentz factors in the range $\Gamma\sim 100-400$, on
the lower end of what is generally observed in Fermi GRBs. Surprisingly, their
lower cutoff energies $E_c$ compared to other Fermi-LAT GRBs arise not
predominantly from the lower Lorentz factors, but also at a comparable level
from differences in variability time, luminosity, and high-energy photon index.
Finally, particularly low $E_c$ values may prevent detection by Fermi-LAT, thus
introducing a bias in the Fermi-LAT GRB sample against GRBs with low Lorentz
factors or variability times.",1706.01481v2
2017-07-20,Model-Independent Constraints on Lorentz Invariance Violation via the Cosmographic Approach,"Since Lorentz invariance plays an important role in modern physics, it is of
interest to test the possible Lorentz invariance violation (LIV). The time-lag
(the arrival time delay between light curves in different energy bands) of
Gamma-ray bursts (GRBs) has been extensively used to this end. However, to our
best knowledge, one or more particular cosmological models were assumed {\it a
priori} in (almost) all of the relevant works in the literature. So, this makes
the results on LIV in those works model-dependent and hence not so robust in
fact. In the present work, we try to avoid this problem by using a
model-independent approach. We calculate the time delay induced by LIV with the
cosmic expansion history given in terms of cosmography, without assuming any
particular cosmological model. Then, we constrain the possible LIV with the
observational data, and find weak hints for LIV.",1707.06367v2
2017-10-31,Lorentz violation with a universal minimum speed as foundation of de Sitter relativity,"We aim to investigate the theory of Lorentz violation with an invariant
minimum speed so-called Symmetrical Special Relativity (SSR) from the viewpoint
of its metric. Thus we should explore the nature of SSR-metric in order to
understand the origin of the conformal factor that appears in the metric by
deforming Minkowski metric by means of an invariant minimum speed that breaks
down Lorentz symmetry. So we are able to realize that there is a similarity
between SSR and a new space with variable negative curvature ($-\infty<\mathcal
R<0$) connected to a set of infinite cosmological constants
($0<\Lambda<\infty$), working like an extended de Sitter (dS) relativity, so
that such extended dS-relativity has curvature and cosmological ""constant""
varying in the time. We obtain a scenario that is more similar to dS-relativity
given in the approximation of a slightly negative curvature for representing
the current universe having a tiny cosmological constant. Finally we show that
the invariant minimum speed provides the foundation for understanding the
kinematics origin of the extra dimension considered in dS-relativity in order
to represent the dS-length.",1710.11497v1
2017-12-14,Lorentz-diffeomorphism edge modes in 3d gravity,"The proper definition of subsystems in gauge theory and gravity requires an
extension of the local phase space by including edge mode fields. Their role is
on the one hand to restore gauge invariance with respect to gauge
transformations supported on the boundary, and on the other hand to parametrize
the largest set of boundary symmetries which can arise if both the gauge
parameters and the dynamical fields are unconstrained at the boundary. In this
work we construct the extended phase space for three-dimensional gravity in
first order connection and triad variables. There, the edge mode fields consist
of a choice of coordinate frame on the boundary and a choice of Lorentz frame
on the bundle, which together constitute the Lorentz-diffeomorphism edge modes.
After constructing the extended symplectic structure and proving its gauge
invariance, we study the boundary symmetries and the integrability of their
generators. We find that the infinite-dimensional algebra of boundary
symmetries with first order variables is the same as that with metric
variables, and explain how this can be traced back to the expressions for the
diffeomorphism Noether charge in both formulations. This concludes the study of
extended phase spaces and edge modes in three-dimensional gravity, which was
done previously by the author in the BF and Chern-Simons formulations.",1712.05269v2
2017-12-15,"On Abraham-Lorentz force, Unruh and Hawking radiations","Assuming the radiation emitted by an accelerating charge follows the Unruh
radiation, we obtained the characteristics of the de Broglie wave associated
with the accelerating charge. The de Broglie wavelength of the accelerating
charged particle is found to be inversely proportional to the temperature of
the emitted radiation. Merging the Abraham-Lorentz and Unruh formulae shows
that the particle de Broglie wavelength is found to vary inversely with its
acceleration. It is found to have the same structure as that of the Wien's
displacement law relating the maximum wavelength of the Black Body radiation to
its temperature. A maximum acceleration that a charged particle can attain is
derived that sets a limit to the the maximum electric field. The
Abraham-Lorentz force for a black hole radiation is found to be proportional to
its evaporation rate. The final mass of the black hole left-over is found to be
$\sqrt{\frac{\alpha\hbar c}{24 \pi G} }$, where $G$ is the gravitational
constant, $c$ the speed of light, $h=2\pi\hbar$ is the Planck constant, and
$\alpha$ is the fine structure constant. The minimum entropy and spin of the
black hole emitting Hawking radiation are, respectively, found to be
$(\alpha/6) k_B$ and $(\alpha/6)\hbar$. The presently observed universal
acceleration is a manifestation of the Unruh black body temperature of
$10^{-29}K$. This agrees with the black body radiation temperature ($T$)
relating $TR=const.$ prevailing since the time of the big bang, where $R$ is
the universe radius.",1712.05780v1
2018-10-03,Dispersion Analysis of Finite Difference and Discontinuous Galerkin Schemes for Maxwell's Equations in Linear Lorentz Media,"In this paper, we consider Maxwell's equations in linear dispersive media
described by a single-pole Lorentz model for electronic polarization. We study
two classes of commonly used spatial discretizations: finite difference methods
(FD) with arbitrary even order accuracy in space and high spatial order
discontinuous Galerkin (DG) finite element methods. Both types of spatial
discretizations are coupled with second order semi-implicit leap-frog and
implicit trapezoidal temporal schemes studied in our previous research [5,6].
By performing detailed dispersion analysis for the semi-discrete and fully
discrete schemes, we obtain rigorous quantification of the dispersion error for
Lorentz dispersive dielectrics. In particular, comparisons of dispersion error
can be made taking into account the model parameters, and mesh sizes in the
design of the two types of schemes. The results for the numerical dispersion
analysis can guide us in the optimal choice of discretization parameters for
the more complicated and nonlinear models. The numerical dispersion analysis of
the fully discrete FD and DG schemes, for the dispersive Maxwell model
considered in this paper, clearly indicate the dependence of the numerical
dispersion errors on spatial and temporal discretizations, their order of
accuracy, mesh discretization parameters and model parameters. The results
obtained here cannot be arrived at by considering discretizations of Maxwell's
equations in free space. In particular, our results contrast the advantages and
disadvantages of using high order FD or DG schemes and leap-frog or trapezoidal
time integrators over different frequency ranges using a variety of measures of
numerical dispersion errors. Finally, we highlight the limitations of the
second order accurate temporal discretizations considered.",1810.01723v1
2018-10-01,A New Set of Maxwell-Lorentz Equations and Rediscovery of Heaviside-Maxwellian (Vector) Gravity from Quantum Field Theory,"We show that if we start with the free Dirac Lagrangian, and demand local
phase invariance, assuming the total phase coming from two independent
contributions associated with the charge and mass degrees of freedom of charged
Dirac particles, then we are forced to introduce two massless independent
vector fields for charged Dirac particles that generate all of electrodynamics
and gravitodynamics of Heaviside's Gravity of 1893 or Maxwellian Gravity and
specify the charge and mass currents produced by charged Dirac particles. From
this approach we found: (1) a new set of Maxwell-Lorentz equations, (2) two
equivalent sets of gravito-Maxwell-Lorentz equations (3) a gravitational
correction to the standard Lagrangian of electrodynamics, which, for a neutral
massive Dirac particle, reduces to the Lagrangian for gravitodynamics, (4)
attractive interaction between two static like masses, contrary to the
prevalent view of many field theorists and (5) gravitational waves emanating
from the collapsing process of self gravitating systems carry positive energy
and momentum in the spirit of Maxwell's electromagnetic theory despite the fact
that the intrinsic energy of static gravitoelectromagnetic fields is negative
as dictated by Newton's gravitational law and its time-dependent extensions to
Heaviside-Maxwellian Gravity (HMG). Fundamental conceptual issues in linearized
Einstein's Gravity are also discussed.",1810.04791v2
2019-06-17,Applying the resonant-state expansion to realistic materials with frequency dispersion,"The dispersive resonant-state expansion, developed for an accurate
calculation of the resonant states in open optical systems with frequency
dispersion, is applied here to realistic materials, such as metallic
nanoparticles and semiconductor microspheres. The material permittivity is
determined by fitting the measured indices of refraction and absorption with a
generalized Drude-Lorentz model containing a number of poles in the complex
frequency plane. Each Drude or Lorentz pole generates an infinite series of
resonant states. Furthermore, for small nanoparticles, each of these poles
produces a distinct surface plasmon polariton mode. The evolution of these
multiple surface modes with increasing radius traces the transition from the
electrostatic limit to significant retardation and radiation. Treating the
optical phonon range in a semiconductor microsphere, a reststrahlen band
separating the resonant states is found. Considering a small energy range
around the semiconductor band gap, the transition from absorption to gain is
described by inverting the Lorentz pole weight, which results in the formation
of lasing resonant states. Interestingly, the series of resonant states
converging towards the absorption pole from the lower frequency side reshapes
for a gain pole into a clockwise loop approaching the pole from the higher
frequency side, being separated from a series spanning from low to high
frequencies and containing the lasing modes.",1906.07007v1
2019-06-27,Covariant hamiltonian for gravity coupled to $p$-forms,"We review the covariant canonical formalism initiated by D'Adda, Nelson and
Regge in 1985, and extend it to include a definition of form-Poisson brackets
(FPB) for geometric theories coupled to $p$-forms, gauging free differential
algebras. The form-Legendre transformation and the form-Hamilton equations are
derived from a $d$-form Lagrangian with $p$-form dynamical fields $\phi$.
Momenta are defined as derivatives of the Lagrangian with respect to the
""velocities"" $d\phi$ and no preferred time direction is used. Action invariance
under infinitesimal form-canonical transformations can be studied in this
framework, and a generalized Noether theorem is derived, both for global and
local symmetries. We apply the formalism to vielbein gravity in $d=3$ and
$d=4$. In the $d=3$ theory we can define form-Dirac brackets, and use an
algorithmic procedure to construct the canonical generators for local Lorentz
rotations and diffeomorphisms. In $d=4$ the canonical analysis is carried out
using FPB, since the definition of form-Dirac brackets is problematic. Lorentz
generators are constructed, while diffeomorphisms are generated by the Lie
derivative. A ""doubly covariant"" hamiltonian formalism is presented, allowing
to maintain manifest Lorentz covariance at every stage of the Legendre
transformation. The idea is to take curvatures as ""velocities"" in the
definition of momenta.",1906.11852v2
2019-07-22,Exploring the effect of Lorentz invariance violation with the currently running long-baseline experiments,"Neutrinos are the fundamental particles, blind to all kind of interactions
except the weak and gravitational. Hence, they can propagate very long
distances without any deviation. This characteristic property can thus provide
an ideal platform to investigate Planck suppressed physics through their long
distance propagation. In this work, we intend to investigate CPT violation
through Lorentz invariance violation (LIV) in the long-baseline accelerator
based neutrino experiments. Considering the simplest four-dimensional Lorentz
violating parameters, for the first time, we obtain the sensitivity limits on
the LIV parameters from the currently running long-baseline experiments T2K and
NO$\nu$A. In addition to this, we show their effects on mass hierarchy and CP
violation sensitivities by considering NO$\nu$A as a case study. We find that
the sensitivity limits on LIV parameters obtained from T2K are much weaker than
that of NO$\nu$A and the synergy of T2K and NO$\nu$A can improve these
sensitivities. All these limits are slightly weaker ($2 \sigma$ level) compared
to the values extracted from Super-Kamiokande experiment with atmospheric
neutrinos. Moreover, we observe that the mass hierarchy and CPV sensitivities
are either enhanced or deteriorated significantly in the presence of LIV as
these sensitivities crucially depend on the new CP-violating phases. We also
present the correlation between $\sin^2 \theta_{23}$ and the LIV parameter
$|a_{\alpha \beta}|$, as well as $\delta_{CP}$ and $|a_{\alpha \beta}|$.",1907.09145v2
2019-10-10,A relativistic particle pusher for ultra-strong electromagnetic fields,"Abridged. Kinetic plasma simulations are nowadays commonly used to study a
wealth of non-linear behaviours and properties in laboratory and space plasmas.
In particular, in high-energy physics and astrophysics, the plasma usually
evolves in ultra-strong electromagnetic fields produced by intense laser beams
for the former or by rotating compact objects such as neutron stars and black
holes for the latter. In these ultra-strong electromagnetic fields, the
gyro-period is several orders of magnitude smaller than the timescale on which
we desire to investigate the plasma evolution. Some approximations are required
like for instance artificially decreasing the electromagnetic field strength
which is certainly not satisfactory. The main flaw of this downscaling is that
it cannot reproduce particle acceleration to ultra-relativistic speeds with
Lorentz factor above $\gamma \approx 10^3-10^4$. In this paper, we design a new
algorithm able to catch particle motion and acceleration to Lorentz factor up
to $10^{15}$ or even higher by using Lorentz boosts to special frames where the
electric and magnetic field are parallel. Assuming that these fields are
locally uniform in space and constant in time, we solve analytically the
equation of motion in a tiny region smaller than the length scale of the
spatial and temporal gradient of the field.",1910.04591v3
2019-10-17,Generalization of the Haldane conjecture to SU($n$) chains,"Recently, SU(3) chains in the symmetric and self-conjugate representations
have been studied using field theory techniques. For certain representations,
namely rank-$p$ symmetric ones with $p$ not a multiple of 3, it was argued that
the ground state exhibits gapless excitations. For the remaining
representations considered, a finite energy gap exists above the ground state.
In this paper, we extend these results to SU($n$) chains in the symmetric
representation. For a rank-$p$ symmetric representation with $n$ and $p$
coprime, we predict gapless excitations above the ground state. If $p$ is a
multiple of $n$, we predict a unique ground state with a finite energy gap.
Finally, if $p$ and $n$ have a greatest common divisor $1<q<n$, we predict a
ground state degeneracy of $n/q$, with a finite energy gap. To arrive at these
results, we derive a non-Lorentz invariant flag manifold sigma model
description of the SU($n$) chains, and use the renormalization group to show
that Lorentz invariance is restored at low energies. We then make use of
recently developed anomaly matching conditions for these Lorentz-invariant
models. We also review the Lieb-Shultz-Mattis-Affleck theorem, and extend it to
SU($n$) models with longer range interactions.",1910.08196v2
2020-01-14,Lorentz violation effects in two neutrino double-beta decay,"Observable effects for the Lorentz invariance violation (LIV) at a low energy
scale can also be investigated in double beta decay (DBD). For example, by
comparing the theoretical predictions with a precise analysis of the summed
energy spectra of electrons in $2\nu\beta\beta$ decay, one can constrain the
$\mathring{a}_{of}^{(3)}$ coefficient that governs the time-like component of
the Lorentz invariance violating operator that appears in the Standard Model
extension theory. In this work, we perform calculations of the phase space
factors and summed energy spectra of electrons as well as of their deviations
due to LIV necessary in such experimental investigations. The Fermi functions
needed in the calculation are built up with exact electron wave functions
obtained by numerically solving the Dirac equation in a realistic Coulomb-type
potential with the inclusion of the finite nuclear size and screening effects.
We compared our results with those used in previous LIV investigations that
were obtained with approximate (analytical) Fermi functions and found
differences of up to $30\%$ for heavier nuclei. Our work includes eight
experimentally interesting nuclei. Next, we estimate and discuss the
uncertainties of our calculations associated with uncertainties in Q-values
measurements and the differences raised from the inclusion of the kinematic
terms in the formalism. Finally, we provide the ratio between the standard
phase space factors and their LIV deviations and the energies where the LIV
effects are expected to be maximal. We expect our study to be useful in the
current LIV investigations in $2\nu\beta\beta$ decay and to lead to improved
constraints on the $\mathring{a}_{of}^{(3)}$ coefficient.",2001.04859v2
2020-01-12,Linking extended and plateau emissions of short gamma-ray bursts,"Some short gamma-ray bursts (SGRBs) show a longer lasting emission phase,
called extended emission (EE) lasting $\sim 10^{2-3}\,\rm s$, as well as a
plateau emission (PE) lasting $\sim10^{4-5}\,\rm s$. While a long-lasting
activity of the central engines is a promising explanation for powering both
emissions, their physical origin and their emission mechanisms are still
uncertain. In this work, we study the properties of the EEs and their
connection with the PEs. First, we constrain the minimal Lorentz factor
$\Gamma$ of the outflows powering EEs, using compactness arguments and find
that the outflows should be relativistic, $\Gamma\gtrsim10$. We propose a
consistent scenario for the PEs, where the outflow eventually catches up with
the jet responsible for the prompt emission, injecting energy into the forward
shock formed by the prior jet, which naturally results in a PE. We also derive
the radiation efficiency of EEs and the Lorentz factor of the outflow within
our scenario for 10 well-observed SGRBs accompanied by both EE and PE. The
efficiency has an average value of $\sim3\,\%$ but shows a broad distribution
ranging from $\sim0.01$ to $\sim100\%$. The Lorentz factor is $\sim20-30$,
consistent with the compactness arguments. These results suggest that EEs are
produced by a slower outflow via more inefficient emission than the faster
outflow which causes the prompt emission with a high radiation efficiency.",2001.09851v2
2020-04-30,Sensitivity kernels for inferring Lorentz stresses from normal-mode frequency splittings in the Sun,"Departures from standard spherically symmetric solar models, in the form of
perturbations such as global and local-scale flows and structural
asphericities, result in the splitting of eigenfrequencies in the observed
spectrum of solar oscillations. Drawing from prevalent ideas in normal-mode
coupling theory in geophysical literature, we devise a procedure that enables
the computation of sensitivity kernels for general Lorentz stress fields in the
Sun. Mode coupling due to any perturbation requires careful consideration of
self- and cross-coupling of multiplets. Invoking the isolated-multiplet
approximation allows for limiting the treatment to purely self-coupling,
requiring significantly less computational resources. We identify the presence
of such isolated multiplets under the effect of Lorentz stresses in the Sun.
Currently, solar missions allow precise measurements of self-coupling of
multiplets via ""$a$-coefficients"" and the cross-spectral correlation signal
which enables the estimation of the ""structure coefficients"". We demonstrate
the forward problem for both self-coupling ($a$-coefficients) and
cross-coupling (structure coefficients). In doing so, we plot the self-coupling
kernels and estimate $a$-coefficients arising from a combination of
deep-toroidal and surface-dipolar axisymmetric fields. We also compute the
structure coefficients for an arbitrary general magnetic field (real and
solenoidal) and plot the corresponding ""splitting function"", a convenient way
to visualize the splitting of multiplets under 3D internal perturbations. The
results discussed in this paper pave the way to formally pose an inverse
problem, and infer solar internal magnetic fields.",2004.14536v1
2020-12-31,Hawking Radiation from Universal Horizons,"The persistence of a suitable notion of black hole thermodynamics in Lorentz
breaking theories of gravity is not only a non-trivial consistency test for
such theories, it is also an interesting investigation {\em per se}, as it
might help us identifying the crucial features at the root of these surprising
laws governing such purely gravitational objects. In past investigations,
controversial findings were presented in this sense. With the aim of settling
this issue, we present here two complementary derivations of Hawking radiation
in geometries endowed with universal horizons: a novel feature of back holes in
Lorentz breaking theories of gravity which reproduces several properties
normally characterizing Killing horizons. We find that both the derivations
agree on the fact that the Hawking temperature associated to these geometries
is set by the generalized universal horizon peeling surface gravity, as
required for consistency with extant derivations of the first law of
thermodynamics for these black holes. We shall also comment on the
compatibility of our results with previous alternative derivations and on their
significance for the survival of the generalized second law of black hole
thermodynamics in Lorentz breaking theories of gravity.",2101.00028v3
2012-05-01,Lorentz-invariant CPT violation,"A Lorentz-invariant CPT violation, which may be termed as long-distance CPT
violation in contrast to the familiar short-distance CPT violation, has been
recently proposed. This scheme is based on a non-local interaction vertex and
characterized by an infrared divergent form factor. We show that the Lorentz
covariant $T^{\star}$-product is consistently defined and the energy-momentum
conservation is preserved in perturbation theory if the path integral is
suitably defined for this non-local theory, although unitarity is generally
lost. It is illustrated that T violation is realized in the decay and formation
processes. It is also argued that the equality of masses and decay widths of
the particle and anti-particle is preserved if the non-local CPT violation is
incorporated either directly or as perturbation by starting with the
conventional CPT-even local Lagrangian. However, we also explicitly show that
the present non-local scheme can induce the splitting of particle and
anti-particle mass eigenvalues if one considers a more general class of
Lagrangians.",1205.0152v3
2012-05-10,Increasing the Number of TeV Blazars with Parsec-Scale Kinematics,"We report on our observations of the parsec-scale radio jet structures of
five blazars that have been detected by ground-based TeV gamma-ray telescopes.
These five blazars all belong to the class of high-frequency peaked BL Lac
objects (HBLs), which are the most common blazar type detected at the TeV
energy range. Because of their relative faintness in the radio, these HBLs are
not well represented in other radio blazar surveys. Our observations consist of
five epochs of Very Long Baseline Array (VLBA) imaging from 2006 to 2009, of
each of the five blazars 1ES 1101-232, Markarian 180, 1ES 1218+304, PG
1553+113, and H 2356-309, at frequencies from 5 to 22 GHz. Fundamental jet
properties, including the apparent jet speeds, that can be measured from these
multi-epoch series of VLBA images are presented and compared with other
gamma-ray blazars. Confirming prior work, we find that the TeV HBLs have
significantly slower apparent jet speeds than radio-selected blazars. Together
with other radio properties of the HBL class, this suggests modest Lorentz
factors in their parsec-scale radio jets. This in turn suggests some form of
Lorentz factor gradient in these jets, since they are likely to have high
Lorentz factors in their TeV-emitting regions. The study presented here
approximately doubles the number of TeV HBLs with multi-epoch parsec-scale
kinematic measurements.",1205.2399v1
2017-05-01,Extended Nambu Models: their relation to gauge theories,"Yang-Mills theories supplemented by an additional coordinate constraint,
which is solved and substituted in the original Lagrangian, provide examples of
the so called Nambu models, in the case where such constraints arise from
spontaneous Lorentz symmetry breaking. Some explicit calculations have shown
that, after additional conditions are imposed, Nambu models are capable of
reproducing the original gauge theories, thus making Lorentz violation
unobservable and allowing the interpretation of the corresponding massless
gauge bosons as the Goldstone bosons arising from the spontaneous symmetry
breaking. A natural question posed by this approach in the realm of gauge
theories is to determine under which conditions the recovery of an arbitrary
gauge theory from the corresponding Nambu model, defined by a general
constraint over the coordinates, becomes possible. We refer to these theories
as extended Nambu models (ENM) and emphasize the fact that the {defining
coordinate} constraint is not treated as a standard gauge fixing term. At this
level, the mechanism for generating the constraint is irrelevant and the case
of spontaneous Lorentz symmetry breaking is taken only as a motivation, which
naturally bring this problem under consideration. Using a non-perturbative
Hamiltonian analysis we prove that the ENM yields the original gauge theory
after we demand current conservation for all time, together with the imposition
of the Gauss laws constraints as initial conditions upon the dynamics of the
ENM. The Nambu models yielding electrodynamics, Yang Mills theories and
linearized gravity are particular examples of our general approach.",1705.00528v1
2017-09-13,Intrinsic time lags in blazar flares and the search of Lorentz Invariance Violation signatures,"Some Quantum Gravity models predict a violation of Lorentz invariance.
Namely, the velocity of photons in vacuum could depend on their energies. One
possibility for Lorentz Invariance Violation (LIV) searches is to look for
energy-dependent delays in the arrival time of very high energy (VHE) photons
coming from distant sources such as TeV emitting Active Galactic Nuclei (AGN),
mainly blazars. Up to now, observations of flaring AGN have only provided upper
limits on LIV energy scale since no significant time-delay was found and
confirmed. However, AGN are not perfect sources for such LIV searches because
intrinsic temporal effects can be produced by emission processes, similarly to
what has been observed with gamma-ray bursts. With the beginning of the
Cherenkov Telescope Array (CTA) operations in the coming decade, significant
lags should be measured and the question of the origin of these lags will
arise. In particular, propagation effects (LIV) will have to be disentangled
from source-intrinsic effects. A precise time-dependent modeling of blazar
flares becomes necessary to understand the different origins of these
time-delays. In this contribution we report on time-delay studies for blazars
in the VHE domain. Using dif- ferent time-dependent emission scenarios of
blazar flares, we illustrate their resulting intrinsic spectral lags and
provide tools for further analyses of the fine temporal and spectral behavior
of such astrophysical sources. Tightly constraining intrinsic effects should
then allow to better high- light any extrinsic contribution due to LIV.
Conversely, any significant detection of a time-delay should provide new
constraints on emission scenarios.",1709.04269v1
2017-09-17,Attractive Heaviside-Maxwellian (Vector) Gravity from Special Relativity and Quantum Field Theory,"Adopting two independent approaches (a) Lorentz-invariance of physical laws
and (b) local phase invariance of quantum field theory applied to the Dirac
Lagrangian for massive electrically neutral Dirac particles, we rediscovered
the fundamental field equations of Heaviside Gravity (HG) of 1893 and
Maxwellian Gravity (MG), which look different from each other due to a sign
difference in some terms of their respective field equations. However, they are
shown to represent two mathematical representations of a single physical theory
of vector gravity that we name here as Heaviside-Maxwellian Gravity (HMG), in
which the speed of gravitational waves in vacuum is uniquely found to be equal
to the speed of light in vacuum. We also corrected a sign error in Heaviside's
speculative gravitational analogue of the Lorentz force law. This spin-1 HMG is
shown to produce attractive force between like masses under static condition,
contrary to the prevalent view of field theorists. Galileo's law of
universality of free fall is a consequence of HMG, without any initial
assumption of the equality of gravitational mass with velocity-dependent mass.
We also note a new set of Lorentz-Maxwell's equations having the same physical
effects as the standard set - a byproduct of our present study.",1709.06876v2
2017-09-24,The spinor string in a Clifford substructure of space-time,"We factorize the space-time coordinates of Minkowski space into Weyl spinors
with components in a split Clifford algebra. Poisson brackets are defined for
Clifford-valued canonical variables and applied to the quantization of the
point particle and string. In particular, we obtain the Lorentz algebra for the
quantum string, and show that the string supports both integral and
half-integral spin states. Commutation and anti-commutation relations are
derived for the amplitudes of the spinning string. The Clifford algebra is
augmented with the octonions through an R-algebra tensor product, and we apply
the results of Manogue, Schray and Dray on octonionic Lorentz transformations
to obtain a Lorentz invariant string action in ten dimensions.",1709.08160v12
2018-03-22,Finite Correlation Length Scaling in Lorentz-Invariant Gapless iPEPS Wave Functions,"It is an open question how well tensor network states in the form of an
infinite projected entangled pair states (iPEPS) tensor network can approximate
gapless quantum states of matter. Here we address this issue for two different
physical scenarios: i) a conformally invariant $(2+1)d$ quantum critical point
in the incarnation of the transverse field Ising model on the square lattice
and ii) spontaneously broken continuous symmetries with gapless Goldstone modes
exemplified by the $S=1/2$ antiferromagnetic Heisenberg and XY models on the
square lattice. We find that the energetically best wave functions display {\em
finite} correlation lengths and we introduce a powerful finite correlation
length scaling framework for the analysis of such finite-$D$ iPEPS states. The
framework is important i) to understand the mild limitations of the finite-$D$
iPEPS manifold in representing Lorentz-invariant, gapless many body quantum
states and ii) to put forward a practical scheme in which the finite
correlation length $\xi(D)$ combined with field theory inspired formulae can be
used to extrapolate the data to infinite correlation length, i.e. to the
thermodynamic limit. The finite correlation length scaling framework opens the
way for further exploration of quantum matter with an (expected)
Lorentz-invariant, massless low-energy description, with many applications
ranging from condensed matter to high-energy physics.",1803.08566v1
2018-03-22,Neutrino oscillations and Lorentz Invariance Violation in a Finslerian Geometrical model,"Neutrino oscillations are one of the first evidences of physics beyond the
Standard Model (SM). Since Lorentz Invariance is a fundamental symmetry of the
SM, recently also neutrino physics has been explored to verify the eventual
modification of this symmetry and its potential magnitude. In this work we
study the consequences of the introduction of Lorentz Invariance Violation
(LIV) in the high energy neutrinos propagation and evaluate the impact of this
eventual violation on the oscillation predictions. An effective theory
explaining these physical effects is introduced via Modified Dispersion
Relations. This approach, originally introduced by Coleman and Glashow,
corresponds in our model to a modification of the special relativity geometry.
Moreover, the generalization of this perspective leads to the introduction of a
maximum attainable velocity which is specific of the particle. This can be
formalized in Finsler geometry, a more general theory of space-time. In the
present paper the impact of this kind of LIV on neutrino phenomenology is
studied, in particular by analyzing the corrections introduced in neutrino
oscillation probabilities for different values of neutrino energies and
baselines of experimental interest. The possibility of further improving the
present constraints on CPT-even LIV coefficients by means of our analysis is
also discussed.",1803.08570v2
2018-06-19,COHERENT analysis of neutrino generalized interactions,"Effective neutrino-quark generalized interactions are entirely determined by
Lorentz invariance, so they include all possible four-fermion non derivative
Lorentz structures. They contain neutrino-quark non-standard interactions as a
subset, but span over a larger set that involves effective scalar,
pseudoscalar, axial and tensor operators. Using recent COHERENT data, we derive
constraints on the corresponding couplings by considering scalar, vector and
tensor quark currents and assuming no lepton flavor dependence. We allow for
mixed neutrino-quark Lorentz couplings and consider two types of scenarios in
which: (i) one interaction at the nuclear level is present at a time, (ii) two
interactions are simultaneously present. For scenarios (i) our findings show
that scalar interactions are the most severely constrained, in particular for
pseudoscalar-scalar neutrino-quark couplings. In contrast, tensor and
non-standard vector interactions still enable for sizable effective parameters.
We find as well that an extra vector interaction improves the data fit when
compared with the result derived assuming only the standard model contribution.
In scenarios (ii) the presence of two interactions relaxes the bounds and opens
regions in parameter space that are otherwise closed, with the effect being
more pronounced in the scalar-vector and scalar-tensor cases. We point out that
barring the vector case, our results represent the most stringent bounds on
effective neutrino-quark generalized interactions for mediator masses of order
$\sim 1\,$GeV. They hold as well for larger mediator masses, case in which they
should be compared with limits from neutrino deep-inelastic scattering data.",1806.07424v2
2018-06-30,Robust Constraint on Lorentz Violation Using Fermi-LAT Gamma-Ray Burst Data,"Models of quantum gravity suggest that the vacuum should be regarded as a
medium with quantum structure that may have non-trivial effects on photon
propagation, including the violation of Lorentz invariance. Fermi Large Area
Telescope (LAT) observations of gamma-ray bursts (GRBs) are sensitive probes of
Lorentz invariance, via studies of energy-dependent timing shifts in their
rapidly-varying photon emissions. In this paper we analyze the Fermi-LAT
measurements of high-energy gamma rays from GRBs with known redshifts, allowing
for the possibility of energy-dependent variations in emission times at the
sources as well as a possible non-trivial refractive index in vacuo for
photons. We use statistical estimators based on the irregularity, kurtosis and
skewness of bursts that are relatively bright in the 100 MeV to multi-GeV
energy band to constrain possible dispersion effects during propagation. We
find that the energy scale characterizing a linear energy dependence of the
refractive index should exceed a few $\times 10^{17}$ GeV, and we estimate the
sensitivity attainable with additional future sources to be detected by
Fermi-LAT.",1807.00189v3
2018-07-17,Multimessenger Tests of Einstein's Weak Equivalence Principle and Lorentz Invariance with a High-energy Neutrino from a Flaring Blazar,"The detection of the high-energy ($\sim290$ TeV) neutrino coincident with the
flaring blazar TXS 0506+056, the first and only $3\sigma$ neutrino-source
association to date, provides new, multimessenger tests of the weak equivalence
principle (WEP) and Lorentz invariance. Assuming that the flight time
difference between the TeV neutrino and gamma-ray photons from the blazar flare
is mainly caused by the gravitational potential of the Laniakea supercluster of
galaxies, we show that the deviation from the WEP for neutrinos and photons is
conservatively constrained to have an accuracy of $10^{-6}-10^{-7}$, which is
3--4 orders of magnitude better than previous results placed by MeV neutrinos
from supernova 1987A. In addition, we demonstrate that the association of the
TeV neutrino with the blazar flare sets limits on the energy scales of quantum
gravity for both linear and quadratic violations of Lorentz invariance (LIV) to
$E_{\rm QG, 1}>3.2\times10^{15}-3.7\times10^{16}$ GeV and $E_{\rm QG,
2}>4.0\times10^{10}-1.4\times10^{11}$ GeV. These improve previous limits on
both linear and quadratic LIV energy scales in neutrino propagation by 5--7
orders of magnitude.",1807.06504v2
2018-08-14,A Survey of Changes in Magnetic Helicity Flux on the Photosphere During Relatively Low Class Flares,"Using the 135-second cadence of the photospheric vector data provided by the
Helioseismic and Magnetic Imager telescope on board the Solar Dynamic
Observatory, we examined the time-evolution of magnetic helicity fluxes across
the photosphere during 16 flares with the energy class lower than M5.0. During
the flare in 4 out of 16 events, we found impulsive changes in the helicity
fluxes. This indicates that even the flare with less energy could be associated
with anomalistic transportation of the magnetic helicity across the
photosphere. Accompanying the impulsive helicity fluxes, the poynting fluxes
across the photosphere evolved from positive to negative. As such, the
transportations of magnetic energy across the photosphere were toward solar
interior during these flares. In each of the 4 events, the impulsive change in
the helicity flux was always mainly contributed by abrupt change in horizontal
velocity field on a sunspot located near the flaring polarity inversion line.
The velocity field on each sunspot shows either an obvious vortex patten or an
shearing patten relative to the another magnetic polarity, which tended to
relax the magnetic twist or shear in the corona. During these flares, abrupt
change in the Lorentz force acting on these sunspots were found. The rotational
motions and shearing motions of these sunspots always had the same directions
with the resultant Lorentz forces. These results support the view that the
impulsive helicity transportation during the flare could be driven by the
change in the Lorentz force applied on the photosphere.",1808.04591v1
2018-08-22,Observational constraints on the structure of gamma-ray burst jets,"Motivated by GW170817 we examine constraints that observations put on the
angular structure of long gamma-ray burst (GRB) jets. First, the relatively
narrow observed distribution of $E_{X}/E_{\gamma}$ (the isotropic equivalent
early X-ray afterglow to prompt $\gamma$-ray energy ratio) implies that at any
angle that $\gamma$-rays are emitted the Lorentz factor must be high.
Specifically, the Lorentz factor of $\gamma$-ray emitting material cannot drop
rapidly with angle, and must be $\Gamma(\theta)\gtrsim 50$ even if there are
angles for which the gamma-ray received energy is lower by three orders of
magnitude compared to the jet core. Second, jets with an angular structure of
the $\gamma$-ray emission that over-produce events with a $\gamma$-ray
luminosity below the peak of the observed luminosity function are ruled-out.
This eliminates models in which the $\gamma$-ray energy angular distribution
isn't sufficiently steep and the Lorentz factor distribution isn't sufficiently
shallow. Finally, models with a steep structure (e.g. Gaussian) which are
detected away from the jet core generate afterglow light-curves that were never
observed. We conclude that even if the jet kinetic energy distribution drops
continuously with latitude, efficient $\gamma$-ray emission seems to be
restricted to material with $\Gamma\gtrsim 50$ and is most likely confined to a
narrow region around the core. While our study is confined to long GRBs, where
the observed sample is larger and more complete, there are indications that
similar conclusions may be applicable also to short GRBs. We discuss the
possible implications to the $\gamma$-rays observed in GRB 170817A.",1808.07493v2
2018-12-08,Self-interaction in classical gauge theories and gravitation,"To develop a systematic treatment of the self-interaction problem in
classical gauge theories and general relativity, we study tenable
manifestations of self-interaction: topological phases, and rearrangements of
degrees of freedom appearing in the action. We outline the occurrence of
topological phases in pure field systems. We show that the rearranged
Maxwell-Lorentz electrodynamics is a mathematically consistent and physically
satisfactory theory which describes new entities, dressed charged particles and
radiation. We extend this analysis to cover different modifications of the
Maxwell-Lorentz electrodynamics and the SU(N) Yang-Mills-Wong theory. We take a
brief look at a subtle mechanism of self-interaction in classical strings.
Turning to general relativity, we note that the total energy and momentum of a
system with nontrivial topological content, such as a black hole, are
ambiguous, coordinatization-dependent quantities, which resembles the situation
with paradoxical decompositions in the Banach-Tarski theorem.",1812.03290v3
2018-12-18,Wave dispersion in pulsar plasma: 2. Pulsar frame,"Wave dispersion in a pulsar plasma is discussed emphasizing the relevance of
different inertial frames, notably the plasma rest frame ${\cal K}$ and the
pulsar frame ${\cal K}'$ in which the plasma is streaming with speed
$\beta_{\rm s}$. The effect of a Lorentz transformation on both subluminal,
$|z|<1$, and superluminal, $|z|>1$, waves is discussed. It is argued that the
preferred choice for a relativistically streaming distribution should be a
Lorentz-transformed J\""uttner distribution; such a distribution is compared
with other choices including a relativistically streaming Gaussian
distribution. A Lorentz transformation of the dielectric tensor is written
down, and used to derive an explicit relation between the relativistic plasma
dispersion functions in ${\cal K}$ and ${\cal K}'$. It is shown that the
dispersion equation can be written in an invariant form, implying a one-to-one
correspondence between wave modes in any two inertial frames. Although there
are only three modes in the plasma rest frame, it is possible for
backward-propagating or negative-frequency solutions in ${\cal K}$ to transform
into additional forward-propagating, positive-frequency solutions in ${\cal
K}'$ that may be regarded as additional modes.",1812.07120v2
2018-12-26,Form factors of two-hadron states from a covariant finite-volume formalism,"In this work we develop a Lorentz-covariant version of the previously derived
formalism for relating finite-volume matrix elements to $\textbf 2 + \mathcal J
\to \textbf 2$ transition amplitudes. We also give various details relevant for
the implementation of this formalism in a realistic numerical lattice QCD
calculation. Particular focus is given to the role of single-particle form
factors in disentangling finite-volume effects from the triangle diagram that
arise when $\mathcal J$ couples to one of the two hadrons. This also leads to a
new finite-volume function, denoted $G$, the numerical evaluation of which is
described in detail. As an example we discuss the determination of the $\pi \pi
+ \mathcal J \to \pi \pi$ amplitude in the $\rho$ channel, for which the
single-pion form factor, $F_\pi(Q^2)$, as well as the scattering phase,
$\delta_{\pi\pi}$, are required to remove all power-law finite-volume effects.
The formalism presented here holds for local currents with arbitrary Lorentz
structure, and we give specific examples of insertions with up to two Lorentz
indices.",1812.10504v1
2019-02-13,Gamma rays from red giant wind bubbles entering the jets of elliptical host blazars,"Blazars in elliptical hosts have a population of red giants surrounding their
jet. These stars can carry large wind-blown bubbles into the jets, leading to
gamma-ray emission through bubble-jet interactions. We study the interaction
dynamics and the gamma-ray emission produced when the bubbles formed by red
giant winds penetrate the jet of a blazar in an elliptical galaxy. First, we
characterized the masses and penetration rates of the red giant wind bubbles
that enter the jet. Then, the dynamical evolution of these bubbles under the
jet impact was analysed analytically and numerically, and the radiation losses
of the particles accelerated in the interaction were characterised. Finally,
the synchrotron and the inverse Compton contributions above 100 MeV were
estimated under different jet magnetic fields, powers, and Lorentz factors. We
find that an analytical dynamical model is a reasonable approximation for the
red giant wind bubble-jet interaction. The radiation produced by these wind
bubbles interacting with a jet can have a duty cycle of up to 1. For realistic
magnetic fields, gamma rays could be detectable from sources within the local
universe, preferentially from those with high Lorentz factors (of about 10),
and this could be a relatively common phenomenon for these sources. For
magnetic fields in equipartition with the jet power, and high acceleration
rates, synchrotron gamma rays may be detectable even for modest Lorentz factors
(of about 3), but with a much lower duty cycle.",1902.05008v1
2019-03-24,Enhancement of superluminal weak values under Lorentz boost,"We study the local group velocity defined as the weak value of the velocity
operator in the (1+1) dimensional Klein-Gordon as well as Dirac theory. It was
shown by Berry [ J. Phys. A 45, 185308 (2012)] that when the pre- and
post-selected states for evaluating the weak value are chosen at random from an
ensemble of available states, the local group velocity has a universal
probability distribution which can have both subluminal and superluminal
components. In this work, we numerically explore the role of Lorentz boost and
its impact on the superluminal fraction of the total probability distribution.
We show that the dependence (enhancement) of the superluminal fraction on
Lorentz boost of the total probability distribution differs both qualitatively
and quantitatively for the Klein-Gordon waves and Dirac waves. For the
Klein-Gordan waves, the asymmetry in the distribution of group velocities
around the zero velocity point in the laboratory frame is entirely responsible
for the observation of relative enhancement in the boosted frame. On the other
hand, for the Dirac waves, we observe an enhancement irrespective of whether
the laboratory frame velocity distribution is symmetric or not.",1903.10029v2
2019-03-28,Reversed dynamo at small scales and large magnetic Prandtl number,"We show that at large magnetic Prandtl numbers, the Lorentz force does work
on the flow at small scales and drives fluid motions, whose energy is
dissipated viscously. This situation is opposite to that in a normal dynamo,
where the flow does work against the Lorentz force. We compute the spectral
conversion rates between kinetic and magnetic energies for several magnetic
Prandtl numbers and show that normal (forward) dynamo action occurs on large
scales over a progressively narrower range of wavenumbers as the magnetic
Prandtl number is increased. At higher wavenumbers, reversed dynamo action
occurs, i.e., magnetic energy is converted back into kinetic energy at small
scales. We demonstrate this in both direct numerical simulations forced by
volume stirring and in large eddy simulations of solar convectively driven
small-scale dynamos. Low density plasmas such as stellar coronae tend to have
large magnetic Prandtl numbers, i.e., the viscosity is large compared with the
magnetic diffusivity. The regime in which viscous dissipation dominates over
resistive dissipation for large magnetic Prandtl numbers was also previously
found in large eddy simulations of the solar corona, i.e., our findings are a
more fundamental property of MHD that is not just restricted to dynamos.
Viscous energy dissipation is a consequence of positive Lorentz force work,
which may partly correspond to particle acceleration in close-to-collisionless
plasmas. This is, however, not modeled in the MHD approximation employed. By
contrast, resistive energy dissipation on current sheets is expected to be
unimportant in stellar coronae.",1903.11869v2
2019-04-15,Probing an X-ray flare pattern in Mrk 421 induced by multiple stationary shocks: a solution to the bulk Lorentz factor crisis,"The common observations of multiple radio VLBI stationary knots in
high-frequency-peaked BL Lacs (HBLs) can be interpreted as multiple
recollimation shocks accelerating particles along jets. This approach can
resolve the so-called ""bulk Lorentz factor crisis"" of sources with high Lorentz
factor, deduced from maximum gamma-gamma opacity and fast variability, and
apparently inconsistent slow/stationary radio knots. It also suggests that a
unique pattern of the non-thermal emission variability should appear after each
strong flare. Taking advantage of the 13 years of observation of the HBL Mrk
421 by the X-ray Telescope on the Neil Gehrels Swift Observatory Swift-XRT, we
probe for such an intrinsic variability pattern. Its significance is then
statistically estimated via comparisons with numerous similar simulated
lightcurves. A suggested variability pattern is identified, consistent with a
main flare emission zone located in the most upstream 15.3 GHz radio knot at
0.38 mas from the core. Subsequent flux excesses in the lightcurve are
consistent with a perturbation crossing all the downstream radio knots with a
constant apparent speed of 45 c. The significance of the observed variability
pattern not arising from stochastic processes is found above 3 standard
deviations, opening a promising path for further investigations in other
blazars and with other energy bands. In addition to highlight the role of
stationary radio knots as high-energy particle accelerators in jets, the
developed method allows estimates of the apparent speed and size of a jet
perturbation without the need to directly observe any motion in jets.",1904.06802v1
2019-11-06,First search for Lorentz violation in double beta decay with scintillating calorimeters,"We present the search for Lorentz violation in the double beta decay of
^{82}Se~with CUPID-0, using an exposure of 9.95 kg x y. We found no evidence
for the searched signal and set a limit on the isotropic components of the
Lorentz violating coefficient of $\mathring{a}_{\text{of}}^{(3)} <
4.1\cdot10^{-6}$ GeV (90\% Credible Interval). This results is obtained with a
Bayesian analysis of the experimental data and fully includes the systematic
uncertainties of the model. This is the first limit on
$\mathring{a}_{\text{of}}^{(3)}$ obtained with a scintillating bolometer,
showing the potentiality of this technique.",1911.02446v1
2019-11-11,Angular momentum at null infinity in Einstein-Maxwell theory,"On Minkowski spacetime, the angular momentum flux through null infinity of
Maxwell fields, computed using the stress-energy tensor, depends not only on
the radiative degrees of freedom, but also on the Coulombic parts. However, the
angular momentum also can be computed using other conserved currents associated
with a Killing field, such as the Noether current and the canonical current.
The flux computed using these latter two currents is purely radiative. A
priori, it is not clear which of these is to be considered the true flux of
angular momentum for Maxwell fields. This situation carries over to Maxwell
fields on non-dynamical, asymptotically flat spacetimes for fluxes associated
with the Lorentz symmetries in the asymptotic Bondi-Metzner-Sachs (BMS)
algebra.
  We investigate this question of angular momentum flux in the full
Einstein-Maxwell theory. Using the prescription of Wald and Zoupas, we compute
the charges associated with any BMS symmetry on cross-sections of null
infinity. The change of these charges along null infinity then provides a flux.
For Lorentz symmetries, the Maxwell fields contribute an additional term,
compared to the Wald-Zoupas charge in vacuum general relativity, to the charge
on a cross-section. With this additional term, the flux associated with Lorentz
symmetries, e.g., the angular momentum flux, is purely determined by the
radiative degrees of freedom of the gravitational and Maxwell fields. In fact,
the contribution to this flux by the Maxwell fields is given by the radiative
Noether current flux and not by the stress-energy flux.",1911.04514v2
2019-12-06,New test of Lorentz invariance using the MICROSCOPE space mission,"We use data from the T-SAGE instrument on board the MICROSCOPE space mission
to search for Lorentz violation in matter-gravity couplings as described by the
Lorentz violating Standard-Model Extension (SME) coefficients
$(\bar{a}_\text{eff})_\mu^w$, where ($\mu = T,X,Y,Z$) and ($w = e,p,n$) for the
electron, proton and neutron. One of the phenomenological consequences of a
non-zero value of those coefficients is that test bodies of different
composition fall differently in an external gravitational field. This is
similar to ""standard"" tests of the universality of free fall, but with a
specific signature that depends on the orbital velocity and rotation of the
Earth. We analyze data from five measurement sessions of MICROSCOPE spread over
a year finding no evidence for such a signature, but setting constraints on
linear combinations of the SME coefficients that improve on best previous
results by one to two orders of magnitude. Additionally, our independent linear
combinations are different from previous ones, which increases the diversity of
available constraints, paving the way towards a full decorrelation of the
individual coefficients.",1912.03030v1
2019-12-06,The Poincaré and BMS flux-balance laws with application to binary systems,"Asymptotically flat spacetimes admit both supertranslations and Lorentz
transformations as asymptotic symmetries. Furthermore, they admit super-Lorentz
transformations, namely superrotations and superboosts, as outer symmetries
associated with super-angular momentum and super-center-of-mass charges. In
this paper, we present comprehensively the flux-balance laws for all such BMS
charges. We distinguish the Poincar\'e flux-balance laws from the proper BMS
flux-balance laws associated with the three relevant memory effects defined
from the shear, namely, the displacement, spin and center-of-mass memory
effects. We scrutinize the prescriptions used to define the angular momentum
and center-of-mass. In addition, we provide the exact form of all Poincar\'e
and proper BMS flux-balance laws in terms of radiative symmetric tracefree
multipoles. Fluxes of energy, angular momentum and octupole super-angular
momentum arise at 2.5PN, fluxes of quadrupole supermomentum arise at 3PN and
fluxes of momentum, center-of-mass and octupole super-center-of-mass arise at
3.5PN. We also show that the BMS flux-balance laws lead to integro-differential
consistency constraints on the radiation-reaction forces acting on the sources.
Finally, we derive the exact form of all BMS charges for both an initial Kerr
binary and a final Kerr black hole in an arbitrary Lorentz and supertranslation
frame, which allows to derive exact constraints on gravitational waveforms
produced by binary black hole mergers from each BMS flux-balance law.",1912.03164v3
2019-12-17,Stokes vectors and Minkowski spacetime: Structural parallels,"The Stokes formalism of polarization physics has astounding structural
parallels with the formalism used for relativity theory in Minkowski spacetime.
The structure and symmetry properties of the Mueller matrices are the same as
those for the matrix representations of the electromagnetic tensor and the
Lorentz transformation operator. The absorption terms $\eta_k$ in the Mueller
matrix correspond to the electric field components $E_k$ in the electromagnetic
tensor and the Lorentz boost terms $\gamma_k$ in the Lorentz transformation
matrix, while the anomalous dispersion terms $\rho_k$ correspond to the
magnetic field components $B_k$ and the spatial rotation angles $\phi_k$. In a
Minkowski-type space spanned by the Stokes $I,Q,U,V$ parameters, the Stokes
vector for 100 % polarized light is a null vector living on the surface of null
cones, like the energy-momentum vector of massless particles in ordinary
Minkowski space. Stokes vectors for partially polarized light live inside the
null cones like the momentum vectors for massive particles. In this description
the depolarization of Stokes vectors appears as a ""mass'' term, which has its
origin in a symmetry breaking caused by the incoherent superposition of
uncorrelated fields or wave packets, without the need to refer to a ubiquitous
Higgs field as is done in particle physics. The rotational symmetry of Stokes
vectors and Mueller matrices is that of spin-2 objects, in contrast to the
spin-1 nature of the electromagnetic field. The reason for this difference is
that the Stokes objects have substructure: they are formed from bilinear tensor
products between spin-1 objects, the Jones vectors and Jones matrices. The
governing physics takes place at the substructure level.",1912.08614v1
2019-12-28,Hadron properties in a nuclear medium and effective nuclear force from quarks: the quark-meson coupling model,"We give a short review of the quark-meson coupling (QMC) model, the
quark-based model of finite nuclei and hadron interactions in a nuclear medium,
highlighting on the relationship with the Skyrme effective nuclear forces. The
model is based on a mean field description of nonoverlapping nucleon MIT bags
bound by the self-consistent exchange of Lorentz-scalar-isoscalar,
Lorentz-vector-isoscalar, and Lorentz-vector-isovector meson fields directly
coupled to the light quarks up and down. In conventional nuclear physics the
Skyrme effective forces are very popular, but, there is no satisfactory
interpretation of the parameters appearing in the Skyrme forces. Comparing a
many-body Hamiltonian generated by the QMC model in the zero-range limit with
that of the Skyrme force, it is possible to obtain a remarkable agreement
between the Skyrme force and the QMC effective interaction. Furthermore, it is
shown that 3-body and higher order N-body forces are naturally included in the
QMC-generated effective interaction.",1912.12461v1
2020-04-30,Complete Set of Dimension-8 Operators in the Standard Model Effective Field Theory,"We present a complete list of the dimension 8 operator basis in the standard
model effective field theory using group theoretic techniques in a systematic
and automated way. We adopt a new form of operators in terms of the irreducible
representations of the Lorentz group, and identify the Lorentz structures as
states in a $SU(N)$ group. In this way, redundancy from equations of motion is
absent and that from integration-by-part is treated using the fact that the
independent Lorentz basis forms an invariant subspace of the $SU(N)$ group. We
also decompose operators into the ones with definite permutation symmetries
among flavor indices to deal with subtlety from repeated fields. For the first
time, we provide the explicit form of independent flavor-specified operators in
a systematic way. Our algorithm can be easily applied to higher dimensional
standard model effective field theory and other effective field theories,
making these studies more approachable.",2005.00008v3
2020-04-30,"X-ray Afterglows from the Gamma-Ray Burst ""Large(r)-Angle"" Emission","We derive basic analytical results for the timing and decay of the
GRB-counterpart and delayed-afterglow light-curves for a brief emission episode
from a relativistic surface endowed with angular structure, consisting of a
uniform Core of size theta_c (Lorentz factor Gamma_c and surface emissivity
i_nu are angle-independent) and an axially-symmetric power-law Envelope (Gamma
~ theta^{-g}).
  In this Large-Angle Emission (LAE) model, radiation produced during the
prompt emission phase (GRB) at angles theta > theta_c arrives at observer well
after the burst (delayed emission). The dynamical time-range of the very
fast-decaying GRB ""tail"" and of the flat afterglow ""plateau"", and the
morphology of GRB counterpart/afterglow, are all determined by two parameters:
the Core's parameter Gamma_c*theta_c and the Envelope's Lorentz factor index g,
leading to three types of light-curves that display three post-GRB phases (type
1: tail, plateau/slow-decay, post-plateau/normal-decay), two post-GRB phases
(type 2: tail and fast-decay), or just one (type 3: normal decay).
  We show how X-ray light-curve features can be used to determine Core and
Envelope dynamical and spectral parameters.
  Testing of the LAE model is done using the Swift/XRT X-ray emission of two
afterglows of type 1 (060607A, 061121), one of type 2 (061110A), and one of
type 3 (061007). We find that the X-ray afterglows with plateaus require an
Envelope Lorentz factor Gamma ~ theta^{-2} and a comoving-frame emissivity i_nu
~ theta^2, thus, for a typical afterglow spectrum F_nu ~ nu^{-1}, the lab-frame
energy release is uniform over the emitting surface.",2005.00104v1
2020-05-23,Thermal aspects of interacting quantum gases in Lorentz-violating scenarios,"In this work, we study the interaction of quantum gases in Lorentz-violating
scenarios considering both boson and fermion sectors. In the latter case, we
investigate the consequences of a system governed by scalar, vector,
pseudovector and tensor operators. Besides, we examine the implications of
$\left( \hat{k}_{a}\right) ^{\kappa }$ and $\left( \hat{k}_{c}\right) ^{\kappa
\xi }$ operators for the boson case as well. For doing so, we regard the grand
canonical ensemble seeking the so-called partition function, which suffices to
provide analytically the calculations of interest, i.e., mean particle number,
entropy, mean total energy and pressure. Furthermore, in low temperature
regime, such quantities converge until reaching a similar behavior being in
contrast with what is shown in high temperature regime, which brings out the
differentiation of their effects. In addition, particle number, entropy and
energy exhibit an extensive characteristic even in the presence of Lorentz
violation. Finally, for peseudovector and tensor operators, we notice a
remarkable feature due to the breaking process of spin degeneracy: the system
turns out to have greater energy and particle number for the spin-down
particles in comparison with spin-up ones.",2005.11453v2
2020-06-05,The FRB-SGR Connection,"The discovery that the Galactic SGR 1935$+$2154 emitted FRB 200428
simultaneous with a gamma-ray flare demonstrated the common source and
association of these phenomena. If FRB radio emission is the result of coherent
curvature radiation, the net charge of the radiating ""bunches"" or waves may be
inferred from the radiated fields, independent of the mechanism by which the
bunches are produced. A statistical argument indicates that the radiating
bunches must have a Lorentz factor $\gtrapprox 10$. The observed radiation
frequencies indicate that their phase velocity (pattern speed) corresponds to
Lorentz factors $\gtrapprox 100$. Coulomb repulsion implies that the electrons
making up these bunches may have yet larger Lorentz factors, limited by their
incoherent curvature radiation. These electrons also Compton scatter the soft
gamma-rays of the SGR. In FRB 200428 the power radiated coherently at radio
frequencies exceeded that of Compton scattering, but in more luminous SGR
outbursts Compton scattering dominates, precluding the acceleration of
energetic electrons. This explains the absence of a FRB associated with the
giant 27 December 2004 outburst of SGR 1806$-$20. SGR with luminosity $\gtrsim
10^{42}$ ergs/s do not emit FRB, while those of lesser luminosity can do so.
""Superbursts"" like FRB 200428 are produced when narrowly collimated FRB are
aligned with the line of sight; they are unusual, but not rare, and
""cosmological"" FRB may be superbursts.",2006.03468v4
2020-06-12,Neutron star inner crust: effects of rotation and magnetic fields,"We study the role of the pasta phases on the properties of rotating and
magnetized neutron stars. In order to investigate such systems, we make use of
two different relativistic mean-field unified inner-crust--core equations of
state, with a different density dependence of the symmetry energy, and an
inner-crust computed within a Thomas-Fermi calculation. Special attention is
given to the crust-core transition density, and the pasta phases effects on the
global properties of stars. The effects of strong magnetic fields and fast
rotation are computed by solving the Einstein-Maxwell equations
self-consistently, taking into account anisotropies induced by the centrifugal
and the Lorentz force. The location of the magnetic field neutral line and the
maximum of the Lorentz force on the equatorial plane are calculated. The
conditions under which they fall inside the inner crust region are discussed.
We verified that models with a larger symmetry energy slope show more
sensitivity to the variation of the magnetic field. One of the maxima of the
Lorentz force, as well as the neutral line, and for a certain range of
frequencies, fall inside the inner crust region. This may have consequences in
the fracture of the crust, and may help explain phenomena associated with star
quakes.",2006.07248v2
2020-08-07,Nonuniqueness of nonrunaway solutions of Abraham-Lorentz-Dirac equation in an external laser pulse,"In the paper \cite{carati95} it was shown that, for motions on a line under
the action of a potential barrier, the third-order Abraham-Lorentz-Dirac
equation presents the phenomenon of nonuniqueness of nonrunaway solutions.
Namely, at least for a sufficiently steep barrier, the physical solutions of
the equation are not determined by the ""mechanical state"" of position and
velocity, and knowledge of the initial acceleration too is required. Due to
recent experiments, both in course and planned, on the interactions between
strong laser pulses and ultra relativistic electrons, it becomes interesting to
establish whether such a nonuniqueness phenomenon extends to the latter case,
and for which ranges of the parameters. In the present work we will consider
just the simplest model, i.e., the case of an electromagnetic plane wave, and
moreover for the Abraham-Lorentz-Dirac equation dealt with in the
nonrelativistic approximation. The result we found is that the nonuniqueness
phenomenon occurs if, at a given frequency of the incoming wave, the field
intensity is sufficiently large. An analytic estimate of such a threshold is
also given. At the moment it is unclear whether such a phenomenon applies also
in the full relativistic case, which is the one of physical interest.",2008.04090v2
2020-08-21,Slowly rotating Einstein-bumblebee black hole solution and its greybody factor in a Lorentz violation model,"We obtain an exact slowly rotating Einstein-bumblebee black hole solution by
solving the corresponding $rr$ and $t\phi$ components of the gravitational
field equations in both cases: A, $b_\mu=(0,b(r),0,0)$; B,
$b_\mu=(0,b(r),\mathfrak{b}(\theta),0)$. Then we check the other gravitational
field equations and the bumblebee field motion equations by using this
solution. We find that in the case A, there exists a slowly rotating black hole
solution indeed for arbitrary LV (Lorentz violation) coupling constant $\ell$;
however as in the case B, there exists this slowly rotating solution if and
only if the coupling constant $\ell$ is as small as or smaller than the angular
momentum $a$. Till now there seems to be no full rotating black hole solution,
so one can't use the Newman-Janis algorithm to generate a rotating solution in
Einstein-bumblebee theory. It is similar as that in Einstein-aether theory
where there exists only some slowly rotating black hole solutions. In order to
study the effects of this Lorentz symmetry broken, we consider the black hole
greybody factor and find that when angular index $l=0$, the LV constant $\ell$
decreases the effective potential and enhances the absorption probability,
which is similar to that of the non-minimal derivative coupling theory.",2008.10474v2
2020-09-02,Implications of $\textit{SU}(2)_L$ gauge invariance for constraints on Lorentz violation,"Lorentz invariance is one of the basic ingredients of quantum field theories
and violations of it are stringently constrained experimentally. Therefore, the
possibility of Lorentz violation (LV) is usually realized at very high energy
scales, resulting in a strong suppression of it (by the new scale) in
experiments. The Standard-Model Extension (SME) parameterizes LV in a
model-independent way, respecting $SU(2)_L$ gauge invariance. This means, e.g.,
that the neutrino and charged-lepton sectors are linked to each other. Hence,
on the one hand, any modification of neutrino properties simultaneously gives
rise to effects for charged leptons, which is why the tight limits on
flavour-off-diagonal LV for neutrinos imply new bounds on modifications of
charged leptons. On the other hand, LV for left-handed charged leptons implies
LV for neutrinos. Since LV modifications of the charged-lepton sector are, in
general, even more constraining than effects in the flavour-diagonal neutrino
sector, we obtain novel tight bounds on LV in the latter. Subsequently, we
apply the same approach to an analysis of time-of-flight data for neutrinos
(detected by IceCube) and photons from gamma ray bursts where discrepancies
have been observed. Our finding is that an explanation of the arrival time
difference between neutrino and photon events by dim-5 operators in the
neutrino sector would lead to unacceptably large LV effects in the
charged-lepton sector.",2009.01247v2
2020-09-22,Effects of Non-locality in Gravity and Quantum Theory,"Spacetime---the union of space and time---is both the actor and the stage
during physical processes in our fascinating Universe. In Lorentz invariant
local theories, the existence of a maximum signalling speed (the ""speed of
light"") determines a notion of causality in spacetime, distinguishing the past
from the future, and the cause from the effect. This thesis is dedicated to the
study of \emph{deviations} from locality. Focussing on a particular class of
\emph{non-local} theories that is both Lorentz invariant and free of ghosts, we
aim to understand the effects of such non-local physics in both gravity and
quantum theory. Non-local ghost-free theories are accompanied by a parameter
$\ell$ of dimension length that parametrizes the scale of non-locality, and for
that reason we strive to express all effects of non-locality in terms of this
symbol. In the limiting case of $\ell=0$ one recovers the local theory, and the
effects of non-locality vanish. In order to address these questions we develop
the notion of non-local Green functions [...]. The results presented in this
thesis establish several effects of a Lorentz invariant, ghost-free
non-locality in the areas of both gravitational and quantum physics. (Full
abstract in document.)",2009.10856v1
2020-10-05,Stochastic resetting of active Brownian particles with Lorentz force,"The equilibrium properties of a system of passive diffusing particles in an
external magnetic field are unaffected by the Lorentz force. In contrast,
active Brownian particles exhibit steady-state phenomena that depend on both
the strength and the polarity of the applied magnetic field. The intriguing
effects of the Lorentz force, however, can only be observed when
out-of-equilibrium density gradients are maintained in the system. To this end,
we use the method of stochastic resetting on active Brownian particles in two
dimensions by resetting them to the line $x=0$ at a constant rate and
periodicity in the $y$ direction. Under stochastic resetting, an active system
settles into a nontrivial stationary state which is characterized by an
inhomogeneous density distribution, polarization and bulk fluxes perpendicular
to the density gradients. We show that whereas for a uniform magnetic field the
properties of the stationary state of the active system can be obtained from
its passive counterpart, novel features emerge in the case of an inhomogeneous
magnetic field which have no counterpart in passive systems. In particular,
there exists an activity-dependent threshold rate such that for smaller
resetting rates, the density distribution of active particles becomes
non-monotonic. We also study the mean first-passage time to the $x$ axis and
find a surprising result: it takes an active particle more time to reach the
target from any given point for the case when the magnetic field increases away
from the axis. The theoretical predictions are validated using Brownian
dynamics simulations.",2010.02103v1
2020-10-18,Large fluctuations and transport properties of the Lévy-Lorentz gas,"The L\'evy-Lorentz gas describes the motion of a particle on the real line in
the presence of a random array of scattering points, whose distances between
neighboring points are heavy-tailed i.i.d. random variables with finite mean.
The motion is a continuous-time, constant-speed interpolation of the simple
symmetric random walk on the marked points. In this paper we study the large
fluctuations of the continuous-time process and the resulting transport
properties of the model, both annealed and quenched, confirming and extending
previous work by physicists that pertain to the annealed framework.
Specifically, focusing on the particle displacement, and under the assumption
that the tail distribution of the interdistances between scatterers is
regularly varying at infinity, we prove a precise large deviation principle for
the annealed fluctuations and present the asymptotics of annealed moments,
demonstrating annealed superdiffusion. Then, we provide an upper large
deviation estimate for the quenched fluctuations and the asymptotics of
quenched moments, showing that the asymptotic diffusive regime conditional on a
typical arrangement of the scatterers is normal diffusion, and not
superdiffusion. Although the L\'evy-Lorentz gas seems to be accepted as a model
for anomalous diffusion, our findings suggest that superdiffusion is a
transient behavior which develops into normal diffusion on long timescales, and
raise a new question about how the transition from the quenched normal
diffusion to the annealed superdiffusion occurs.",2010.09083v4
2020-10-21,Parsec-scale properties of the radio brightest jetted AGN at z > 6,"We present Director's Discretionary Time multi-frequency observations
obtained with the Jansky Very Large Array (VLA) and the Very Long Baseline
Array (VLBA) of the blazar PSO J030947.49+271757.31 (hereafter PSO J0309+27) at
$z = 6.10\pm0.03$. The milliarcsecond angular resolution of our VLBA
observations at 1.5, 5 and 8.4 GHz unveils a bright one-sided jet extended for
$\sim500$ parsecs in projection. This high-z radio-loud AGN is resolved into
multiple compact sub-components, embedded in a more diffuse and faint radio
emission, which enshrouds them in a continuous jet structure. We derive limits
on some physical parameters directly from the observable quantities, such as
viewing angle, Lorentz and Doppler factors. If PSO J0309+27 is a genuine
blazar, as suggested by its X-ray properties, then we find that its bulk
Lorentz factor must be relatively low (less than 5). Such value would be in
favour of a scenario currently proposed to reconcile the paucity of high-z
blazars with respect to current predictions. Nevertheless, we cannot exclude
that PSO J0309+27 is seen under a larger viewing angle, which would imply that
the X-ray emission must be enhanced, for example, by inverse Compton with the
Cosmic Microwave Background. More stringent constraints on the bulk Lorentz
factor in PSO J0309+27 and the other high-z blazars are necessary to test
whether their properties are intrinsically different with respect to the low-z
blazar population.",2010.11193v1
2021-02-12,Material absorption-based carrier generation model for modeling optoelectronic devices,"The generation rate of photocarriers in optoelectronic materials is commonly
calculated using the Poynting vector in the frequency domain. In time-domain
approaches where the nonlinear coupling between electromagnetic (EM) waves and
photocarriers can be accounted for, the Poynting vector model is no longer
applicable. One main reason is that the photocurrent radiates low-frequency EM
waves out of the spectrum of the source, e.g., terahertz (THz) waves are
generated in THz photoconductive antennas. These frequency components do not
contribute to the photocarrier generation since the corresponding photon energy
is smaller than the optoelectronic material's bandgap energy. However, the
instantaneous Poynting vector does not distinguish the power flux of different
frequency components. This work proposes a material absorption-based model
capable of calculating the carrier generation rate accurately in the time
domain. Using the Lorentz dispersion model with poles reside in the optical
frequency region, the instantaneous optical absorption, which corresponds to
the power dissipation in the polarization, is calculated and used to calculate
the generation rate. The Lorentz model is formulated with an auxiliary
differential equation method that updates the polarization current density,
from which the absorbed optical power corresponding to each Lorentz pole is
directly calculated in the time domain. Examples show that the proposed model
is more accurate than the Poynting vector-based model and is stable even when
the generated low-frequency component is strong.",2102.06702v1
2021-03-03,Detecting reconnection sites using the Lorentz Transformations for electromagnetic fields,"We take a pragmatic definition of reconnection to find locations where a
reconnection electric field causes a ExB drift that carries two components of
the magnetic field towards their elimination. With this in mind as our target,
we observe that such locations can be found using a new indicator: the velocity
of the Lorentz transformation that eliminates two components of the local
magnetic field. Serendipitously, the indicator naturally becomes subluminal in
the close proximity of a point where two components of the magnetic field
vanish and it is hard zero at the vanishing location. Everywhere else the
velocity of this Lorentz frame change far exceeds the speed of light. This
property can be quickly applied in practice because computing the frame change
is a local operation that requires only the knowledge of the local magnetic and
electric field: it can be applied in a simulation or in observational data from
a field instrument. We further show that the points identified can be
classified in 6 categories that extend the usual types of magnetic nulls to the
case of 3D reconnection in presence of a guide field. The approach is used to
identify secondary electron scale reconnection sites in a turbulent outflow
from a primary reconnection site in a highly resolved massively parallel fully
kinetic particle in cell simulation. Numerous points are found and their
detailed analysis is reported.",2103.02538v2
2021-04-23,A Kinetic Model of Friction in Strongly Coupled Strongly Magnetized Plasmas,"Plasmas that are strongly magnetized in the sense that the gyrofrequency
exceeds the plasma frequency exhibit novel transport properties that are not
well understood. As a representative example, we compute the friction force
acting on a massive test charge moving through a strongly coupled and strongly
magnetized one-component plasma using a generalized Boltzmann kinetic theory.
Recent works studying the weakly coupled regime have shown that strong
magnetization leads to a transverse component of the friction force that is
perpendicular to both the Lorentz force and velocity of the test charge; in
addition to the stopping power component aligned antiparallel to the velocity.
Recent molecular dynamics simulations have also shown that strong Coulomb
coupling in addition to strong magnetization gives rise to a third component of
the friction force in the direction of the Lorentz force. Here, we show that
the generalized Boltzmann kinetic theory captures these effects, and generally
agrees well with the molecular dynamics simulations over a broad range of
Coulomb coupling and magnetization strength regimes. The theory is also used to
show that a ""gyro"" component of the friction in the direction of the Lorentz
force arises due to asymmetries associated with gyromotion during short-range
collisions. Computing the average motion of the test charge through the
background plasma, the transverse force is found to strongly influence the
trajectory by changing the gyroradius and the gyro friction force is found to
slightly change the gyrofrequency of the test charge resulting in a phase
shift.",2104.11718v1
2021-04-30,Ab-Initio Molecular Dynamics with Screened Lorentz Forces. Part I. Calculation and Atomic Charge Interpretation of Berry Curvature,"The dynamics of a molecule in a magnetic field is significantly different
form its zero-field counterpart. One important difference in the presence of a
field is the Lorentz force acting on the nuclei, which can be decomposed as the
sum of the bare nuclear Lorentz force and a screening force due to the
electrons. This screening force is calculated from the Berry curvature and can
change the dynamics qualitatively. It is therefore important to include the
contributions from the Berry curvature in molecular dynamics simulations in a
magnetic field. In this work, we present a scheme for calculating the Berry
curvature numerically, by a finite-difference technique, addressing challenges
related to the arbitrary global phase of the wave function. The Berry curvature
is calculated as a function of bond distance for H$_2$ at the restricted and
unrestricted Hartree--Fock levels of theory and for CH$^{+}$ as a function of
the magnetic field strength at the restricted Hartree--Fock level of theory.
The calculations are carried out using basis sets of contracted Gaussian
functions equipped with London phase factors (London orbitals) to ensure
gauge-origin invariance. In the paper, we also interpret the Berry curvature in
terms of atomic charges and discuss its convergence in basis sets with and
without London phase factors. Calculation of the Berry curvature allows for its
inclusion in \textit{ab initio} molecular dynamics simulations in a magnetic
field.",2104.14861v1
2021-05-10,Ab-Initio Molecular Dynamics with Screened Lorentz Forces. Part II. Efficient Propagators and Rovibrational Spectra in Strong Magnetic Fields,"Strong magnetic fields have a large impact on the dynamics of molecules. In
addition to the changes of the electronic structure, the nuclei are exposed to
the Lorentz force with the magnetic field being screened by the electrons. In
this work, we explore these effects using ab-initio molecular dynamics
simulations based on an effective Hamiltonian calculated at the Hartree-Fock
level of theory. To correctly include these non-conservative forces in the
dynamics, we have designed a series of novel propagators that show both good
efficiency and stability in test cases. As a first application, we analyze
simulations of He and H$_2$ at two field strengths characteristic of magnetic
white dwarfs (0.1 $B_0 = 2.35 \times 10^4$ T and $B_0 = 2.35 \times 10^5$ T).
While the He simulations clearly demonstrate the importance of electron
screening of the Lorentz force in the dynamics, the extracted rovibrational
spectra of H$_2$ reveal a number of fascinating features not observed in the
field-free case: couplings of rotations/vibrations with the cyclotron rotation,
overtones with unusual selection rules, and hindered rotations that transmute
into librations with increasing field strength. We conclude that our presented
framework is a powerful tool to investigate molecules in these extreme
environments.",2105.04225v1
2021-05-07,Quaternion Space-Time and Matter,"In this work, we use the concept of quaternion time and demonstrate that it
can be applied for description of four-dimensional space-time intervals. We
demonstrate that the quaternion time interval together with the finite speed of
light propagation allow for a simple intuitive understanding of the time
interval measurement during arbitrary relative motion between a signal source
and observer. We derive a quaternion form of Lorentz time dilation and show
that the norm corresponds to the traditional expression of the Lorentz
transformation and represents the measured value of time intervals, making the
new theory inseparable from the theory of measurement. We determine that the
space-time interval in the observer reference frame is given by a conjugate
quaternion expression, which is essential for proper definition of the
quaternion derivatives in the observer reference frame. Then, we apply
quaternion differentiation to an arbitrary potential, which leads to
generalized Lorentz force. The second quaternion derivative of the potential
leads to expressions similar to generalized Maxwell equations. Finally, we
apply the resulting formalism to electromagnetic and gravitational interactions
and show that the new expressions are similar to the traditional expressions,
with the exception of additional terms, related to scalar fields, that need
further study and experimental verification. Therefore, the new mathematical
approach based on Hamilton's quaternions may serve as a useful foundation of
the unified theory of space-time and matter.",2106.06394v1
2021-06-17,Influence of the bus waveguide on the linear and nonlinear response of a taiji microresonator,"We study the linear and nonlinear response of a unidirectional reflector
where a nonlinear breaking of the Lorentz reciprocity is observed. The device
under test consists of a racetrack microresonator, with an embedded S-shaped
waveguide, coupled to an external bus waveguide (BW). This geometry of the
microresonator, known as ""taiji"" microresonator (TJMR), allows to selectively
couple counter-propagating modes depending on the propagation direction of the
incident light and, at the nonlinear level, leads to an effective breaking of
Lorentz reciprocity. Here, we show that a full description of the device needs
to consider also the role of the BW, which introduces (i) Fabry-Perot
oscillations (FPOs) due to reflections at its facets, and (ii) asymmetric
losses, which depend on the actual position of the TJMR. At sufficiently low
powers the asymmetric loss does not affect the unidirectional behavior, but the
FP interference fringes can cancel the effect of the S-shaped waveguide.
However, at high input power, both the asymmetric loss and the FPOs contribute
to the redistribution of the energy between the clockwise and counterclockwise
modes within the TJMR. This strongly modifies the nonlinear response, giving
rise to counter-intuitive features where, due to the FP effect and the
asymmetric losses, the BW properties can determine the violation of the Lorentz
reciprocity and, in particular, the difference between the transmittance in the
two directions of excitation. The experimental results are explained by using
an analytical model based on the transfer matrix approach, a numerical
finite-element model and exploiting intuitive interference diagrams.",2106.09649v1
2021-08-23,Resonant superalgebras for supergravity,"Considering supergravity theory is a natural step in the development of
gravity models. This paper follows the ``algebraic`` path and constructs
possible extensions of the Poincar\'e and Anti-de-Sitter algebras, which
inherit their basic commutation structure. Previously achieved results of this
type are fragmentary and show only a limited fraction of possible algebraic
realizations. Our paper presents the newly obtained symmetry algebras,
evaluated within an efficient pattern-based computational method of generating
the so-called 'resonating' algebraic structures. These supersymmetric
extensions of algebras, going beyond the Poincar\'e and Anti-de Sitter ones,
contain additional bosonic generators $Z_{ab}$ (Lorentz-like), and $U_a$
(translational-like) added to the standard Lorentz generator $J_{ab}$ and
translation generator $P_{a}$. Our analysis includes all cases up to two
fermionic supercharges, $Q_{\alpha}$ and $Y_{\alpha}$. The delivered plethora
of superalgebras includes few past results and offers a vastness of new
examples. The list of the cases is complete and contains all superalgebras up
to two of Lorentz-like, translation-like, and supercharge-like generators
$(JP+Q)+(ZU+Y)=JPZU+QY$. In the latter class, among $667$ founded
superalgebras, the $264$ are suitable for direct supergravity construction. For
each of them, one can construct a unique supergravity model defined by the
Lagrangian. As an example, we consider one of the algebra configurations and
provide its Lagrangian realization.",2108.10304v2
2021-08-18,Relative binary and ternary 4D velocities in the Special Relativity in terms of manifestly covariant Lorentz transformation,"Zbigniew Oziewicz was a pioneer of the 4D space-time approach to covariant
relative velocities. In the 1980s (according to private correspondence) he
discovered two types of 4D relative velocities: binary and ternary, along with
the rules for adding them. They were first published in conference materials in
2004, and the second time in a peer-reviewed journal in 2007. These physically
logical and mathematically precise concepts are so subtle that Oziewicz's
numerous preprints have yet to receive the recognition they deserve.
  This work was planned to be a more review, but a thorough review of the
little-known results was made in an original synthetic manner with numerous
generalizations. The Part I presents the Oziewicz-\'Swierk-Bol\'os (and
Matolsci or Bini-Carini-Jantzen) binary relative velocity and the
Oziewicz-Ungar-Dragan (also Celakoska-Chakmakov-Petrushevski on the basis of
Urbantke, as well as Wyk) ternary relative velocity. The Einstein-Oziewicz and
Einstein-Minkowski velocities, which are a four-dimensional generalization of
Einstein velocities addition, also have a ternary character. This also applies
to Oziewicz-Minkowski relative velocity, which is a time-like equivalent
(generalization) of the canonical ternary velocity. It turns out that the
Lorentz transformation of velocity itself is already ternary anchored. This
fact is explicitly revealed by the manifestly covariant Lorentz transformation
of velocity, which is the main tool of the work.",2108.10725v4
2021-09-08,Casimir force among spheres made of Weyl semimetals breaking Lorentz reciprocity,"The Casimir force and thermal Casimir force originating from quantum
electromagnetic fluctuations at zero and non-zero temperatures, respectively,
are significant in nano- and microscale systems and are well-understood. Less
understood, however, are the Casimir and thermal Casimir forces in systems
breaking Lorentz reciprocity. In this work, we derive a formalism for thermal
Casimir forces between an arbitrary number of spheres based on fluctuational
electrodynamics and scattering theory without the assumption of Lorentz
reciprocity. We study the total Casimir force in systems of two and three Weyl
semimetal spheres with time-reversal symmetry breaking for different
orientations of the momentum-space separation of Weyl nodes in both thermal
equilibrium and nonequilibrium. In thermal nonequilibrium, we show that a net
thermal Casimir force exists not only along the center-to-center displacements
of the spheres, but also in the transverse direction to it due to thermal
emission with non-zero angular momentum. Different symmetries of the system
drive a variety of dynamics such as global rotations, self-propulsion, and
spinning of the spheres. We also show that the Casimir energy in thermal
equilibrium depends on the orientations of the Weyl node directions in the
spheres and that the lateral Casimir force will act between the spheres even in
thermal equilibrium to relax the system into the minimum energy state without
transferring net energy and momentum to the environment. The developed
framework opens a way for investigating many-body dynamics by Casimir and
thermal Casimir forces among arbitrary number of spheres with arbitrary
dielectric function tensors in both thermal equilibrium and nonequilibrium.",2109.03809v1
2021-10-08,Quantisation of Lorentz invariant scalar field theory in non-commutative space-time and its consequence,"Quantisation of Lorentz invariant scalar field theory in
Doplicher-Fredenhagen-Roberts (DFR) space-time, a Lorentz invariant,
non-commutative space-time is studied. Absence of a unique Lagrangian in
non-commutative space-time necessitates us to use an approach to quantisation
that is based on the equations of motion alone. Using this we derive the equal
time commutation relation between Doplicher-Fredenhagen-Roberts-Amorim (DFRA)
scalar field and its conjugate, which has non-commutative dependent
modifications, but the corresponding creation and annihilation operators obey
usual algebra. We show that imposing the condition that the commutation
relation between the field and its conjugate is same as that in the commutative
space-time leads to a deformation of the algebra of quantised oscillators. Both
these deformed commutation relations derived are valid to all orders in the
non-commutative parameter. By analysing the first non-vanishing terms which are
$\theta^3$ order, we show that the deformed commutaton relations scale as
$1/\lambda^4$, where $\lambda$ is the length scale set by the non-commutativity
of the space-time. We also derive the conserved currents for DFRA scalar field.
Further, we analyse the effects of non-commutativity on Unruh effect by
analysing a detector coupled to the DFRA scalar field, showing that the Unruh
temperature is not modified but the thermal radiation seen by the accelerated
observer gets correction due to the non-commutativity of space-time.",2110.03897v1
2021-10-18,"Quantum gravity phenomenology induced in the propagation of UHECR, a kinematical solution in Finsler and generalized Finsler spacetime","It is well-known that the Universe is opaque to the propagation of
Ultra-High-Energy Cosmic Rays (UHECRs) since these particles dissipate energy
during their propagation interacting with the Cosmic Microwave Background (CMB)
mainly in the so-called GZK cut-off phenomenon. Some experimental evidence
seems to hint at the possibility of a dilation of the GZK predicted opacity
sphere. It is well-known that kinematical perturbations caused by supposed
quantum gravity (QG) effects can modify the foreseen GZK opacity horizon. The
introduction of Lorentz Invariance Violation (LIV) can indeed reduce, in some
cases making negligible, the CMB-UHECRs interaction probability. In this work
we explore the effects induced by modified kinematics in the UHECRs
phenomenology from the QG perspective. We explore the possibility of a
geometrical description of the massive fermions interaction with the supposed
quantum structure of spacetime in order to introduce a Lorentz covariance
modifification. The kinematics is amended modifying the Dispersion Relations
(DRs) of free particles in the context of a covariance-preserving framework.
This spacetime description requires a more general geometry than the usual
Riemannian one, indicating for instance the Finsler construction and the
related generalized Finsler spacetime as ideal candidates. Finally we
investigate the correlation between the magnitude of Lorentz covariance
modification and the attenuation length of the photopion production process
related to the GZK cut-off, demonstrating that the predicted opacity horizon
can be dilated even in the context of a theory that does not require any
privileged reference frame.",2110.09184v1
2021-10-18,Neutrino Oscillations and Lorentz Invariance Violation,"This work explores the possibility of resorting to neutrino phenomenology to
detect evidence of new physics, caused by the residual signals of the supposed
quantum structure of spacetime. In particular, this work investigates the
effects on neutrino oscillations and mass hierarchy detection, predicted by
models that violate Lorentz invariance, preserving the spacetime isotropy and
homogeneity. Neutrino physics is the ideal environment where conducting the
search for new ""exotic"" physics, since the oscillation phenomenon is not
included in the original formulation of the minimal Standard Model (SM) of
particles. The confirmed observation of the neutrino oscillation phenomenon is,
therefore, the first example of physics beyond the SM and can indicate the
necessity to resort to new theoretical models. In this work, the hypothesis
that the supposed Lorentz Invariance Violation (LIV) perturbations can
influence the oscillation pattern is investigated. LIV theories are indeed
constructed assuming modified kinematics, caused by the interaction of massive
particles with the spacetime background. This means that the dispersion
relations are modified, so it appears natural to search for effects caused by
LIV in physical phenomena governed by masses, as in the case of neutrino
oscillations. In addition, the neutrino oscillation phenomenon is interesting
since there are three different mass eigenstates and in a LIV scenario, which
preserves isotropy, at least two different species of particle must interact.",2110.09186v1
2021-12-14,Leaky covariant phase spaces: Theory and application to $Λ$-BMS symmetry,"The present thesis aims at providing a unified description of radiative phase
spaces in General Relativity for any value of the cosmological constant using
covariant phase space methods. We start by considering generic asymptotically
locally (A)dS spacetimes with leaky boundary conditions in the
Starobinsky/Fefferman-Graham gauge. The boundary structure is allowed to
fluctuate and plays the role of source yielding some flux of gravitational
radiation at the boundary. The holographic renormalization procedure is
employed to obtain finite surface charges for the whole class of boundary
diffeomorphisms and Weyl rescalings. We then propose a boundary gauge fixing
isolating the radiative boundary degrees of freedom without constraining the
Cauchy problem in asymptotically dS spacetimes. The residual gauge
transformations form the infinite-dimensional $\Lambda$-BMS algebroid, which
reduces to the Generalized BMS algebra of smooth supertranslations and
super-Lorentz transformations in the flat limit. The analysis is repeated in
the Bondi gauge in which we identify the analogues of the Bondi news, mass and
angular momentum aspects in the presence of a cosmological constant. We give a
prescription to perform the flat limit of the phase space and demonstrate how
to use this connection to renormalize the corresponding phase space of
asymptotically locally flat spacetimes at null infinity including smooth
super-Lorentz transformations. In that context, we discuss the memory effects
associated with super-Lorentz vacuum transitions and finally provide a new
definition of the BMS charges whose fluxes are compatible with soft theorems.",2112.07666v1
2022-01-08,Magnetic Reconnection and Energy Extraction from a Spinning Black Hole with Broken Lorentz Symmetry,"In the Penrose process and the Blandford-Znajek mechanism, the rotational
energy of a black hole (BH) is extracted via particle fission and magnetic
tension, respectively. Recently, inspired by a fundamental trait in plasma
astrophysics known as magnetic reconnection (MR), a new energy extraction
mechanism based on the fast reconnection of the magnetic field lines inside the
ergosphere has been proposed by Comisso and Asenjo. In this paper, we
investigate energy extraction caused by MR in the ergosphere of a rapidly
spinning BH with broken Lorentz symmetry by a background bumblebee vector
field. The desired rotating BH solution differentiates from the standard Kerr
BH via the Lorentz symmetry breaking (LSB) parameter $l$, which comes from
nonminimal coupling between the bumblebee field with nonzero vacuum expectation
value and gravity. We find that incorporating $l<0$ in the background is in the
interest of the energy extraction via MR for the fast-spinning BH surrounded by
the plasma with weak magnetization, below what is expected from the scenario by
Comisso and Asenjo. Our analysis robustly indicates that the power of energy
extraction and efficiency of the plasma energization process through fast MR is
more efficient than the Comisso-Asenjo solution, provided that the LSB
parameter is negative, $l<0$. Compared to the Blandford-Znajek mechanism
arising from the underlying background, we also show that MR is a more
efficient energy extraction mechanism if $l<0$.",2201.02765v2
2022-01-19,Extending the Lorentz Factor Range and Sensitivity of Transition Radiation with Compound Radiators,"Transition radiation detectors (TRDs) have been used to identify high-energy
particles (in particular, to separate electrons from heavier particles) in
accelerator experiments. In space, they have been used to identify cosmic-ray
electrons and measure the energies of cosmic-ray nuclei. To date, radiators
have consisted of regular configurations of foils with fixed values of foil
thickness and spacing (or foam or fiber radiators with comparable average
dimensions) that have operated over a relatively restricted range of Lorentz
factors. In order to extend the applicability of future TRDs (for example, to
identify 0.5 - 3 TeV pions, kaons, and protons in the far forward region in a
future accelerator experiment or to measure the energy spectrum of cosmic-ray
nuclei up to 20 TeV/nucleon or higher), there is a need to increase the signal
strength and extend the range of Lorentz factors that can be measured in a
single detector. A possible approach is to utilize compound radiators
consisting of varying radiator parameters. We discuss the case of a compound
radiator and derive the yield produced in a TRD with an arbitrary configuration
of foil thicknesses and spacings.",2201.07901v1
2022-01-20,An Efficient Lorentz Equivariant Graph Neural Network for Jet Tagging,"Deep learning methods have been increasingly adopted to study jets in
particle physics. Since symmetry-preserving behavior has been shown to be an
important factor for improving the performance of deep learning in many
applications, Lorentz group equivariance - a fundamental spacetime symmetry for
elementary particles - has recently been incorporated into a deep learning
model for jet tagging. However, the design is computationally costly due to the
analytic construction of high-order tensors. In this article, we introduce
LorentzNet, a new symmetry-preserving deep learning model for jet tagging. The
message passing of LorentzNet relies on an efficient Minkowski dot product
attention. Experiments on two representative jet tagging benchmarks show that
LorentzNet achieves the best tagging performance and improves significantly
over existing state-of-the-art algorithms. The preservation of Lorentz symmetry
also greatly improves the efficiency and generalization power of the model,
allowing LorentzNet to reach highly competitive performance when trained on
only a few thousand jets. Code and models are available at
\url{https://github.com/sdogsq/LorentzNet-release}.",2201.08187v6
2022-01-27,Entanglement-enhanced test proposal for local Lorentz-symmetry violation via spinor atoms,"Invariance under Lorentz transformations is fundamental to both the standard
model and general relativity. Testing Lorentz-symmetry violation (LSV) via
atomic systems attracts extensive interests in theory and experiment. Some
recent proposals for testing LSV present that the effects of violation can be
described as a local interaction. Further, the test precision of LSV can be
enhanced via quantum entanglement and its quantum Fisher information (QFI)
implicates that the test precision can asymptotically reach the Heisenberg
limit. In general, the limited resolution of collective observables prevents
the detection of large QFI. Here, we propose a multimode many-body quantum
interferometry for testing the LSV parameter $\kappa$ via an ensemble of spinor
atoms. By employing an $N$-atom multimode GHZ state, the test precision can
attain the Heisenberg limit $\Delta \kappa \propto 1/(F^2N)$ with the spin
length $F$ and the atomic number $N$. We find an actual observable (or
practical measurement process) to achieve the ultimate precision and study the
LSV test via an experimentally accessible three-mode interferometry with Bose
condensed spin-1 atoms for example. By selecting suitable input states and
unitary recombination operation, the LSV parameter $\kappa$ can be extracted
via population measurement. Especially, the measurement precision of the LSV
parameter $\kappa$ can beat the standard quantum limit and even approach the
Heisenberg limit via spin mixing dynamics or driving through quantum phase
transitions.
  Our proposed scheme may open up a feasible way for a drastic improvement of
the LSV tests with atomic systems and provide an alternative application of
multi-particle entangled states.",2201.11366v4
2022-02-07,Effects of kinematic and magnetic boundary conditions on the dynamics of convection-driven plane layer dynamos,"Rapidly rotating convection-driven dynamos are investigated under different
kinematic and magnetic boundary conditions using DNS. At a fixed rotation rate,
represented by the Ekman number $E=5\times10^{-7}$, the thermal forcing is
varied from 2 to 20 times its value at the onset of convection
($\mathcal{R}=Ra/Ra_c=2-20$), keeping the fluid properties constant
($Pr=Pr_m=1$). The statistical behavior, force balance and heat transport
characteristics of the dynamos depend on boundary conditions that dictate both
boundary layer and the interior dynamics. At a fixed thermal forcing
($\mathcal{R}=3$), the Ekman plumes in the presence of viscous boundary layers
lead to energetic vortices that result in higher enstrophy and kinetic helicity
with no-slip boundaries compared to free-slip boundaries. The structure and
strength of the magnetic field are also dictated by the boundary conditions.
Though the leading order force balance remains geostrophic, Lorentz force
dominates inside the thermal boundary layer with no-slip, electrically
conducting walls. Here, the Lorentz work term in the turbulent kinetic energy
budget is found to have components that exchange energy from the velocity field
to the magnetic field, and vice-versa. However, with no-slip, insulated walls,
all Lorentz work components perform unidirectional energy transfer to produce
magnetic energy from the kinetic energy of the fluid. The heat transfer
enhancement in dynamos, compared to non-magnetic rotating convection, exhibits
a peak in the range $\mathcal{R}=3-5$. For free-slip conditions, dynamo action
may alter the heat transport by suppressing the formation of large-scale
vortices. However, the highest heat transfer enhancement occurs when the
boundaries are no-slip, electrically conducting walls.",2202.03235v1
2022-02-17,Escape Dynamics in an Anisotropically Driven Brownian Magneto-System,"Thermally activated escape of a Brownian particle over a potential barrier is
well understood within Kramers theory. When subjected to an external magnetic
field, the Lorentz force slows down the escape dynamics via a rescaling of the
diffusion coefficient without affecting the exponential dependence on the
barrier height. Here, we study the escape dynamics of a charged Brownian
particle from a two-dimensional truncated harmonic potential under the
influence of Lorentz force due to an external magnetic field. The particle is
driven anisotropically by subjecting it to noises with different strengths
along different spatial directions. We show that the escape time can largely be
tuned by the anisotropic driving. While the escape process becomes anisotropic
due to the two different noises, the spatial symmetry is restored in the limit
of large magnetic fields. This is attributed to the Lorentz force induced
coupling between the spatial degrees of freedom which makes the difference
between two noises irrelevant at high magnetic fields. The theoretical
predictions are verified by Brownian dynamics simulations. In principle, our
predictions can be tested by experiments with a Brownian gyrator in the
presence of a magnetic field.",2202.08559v3
2022-07-29,Polarizations of Gravitational Waves in the Bumblebee Gravity Model,"Lorentz violation modifies the dispersion relation of gravitational waves
(GWs), and induces birefringence and anisotropy in propagation. Our study shows
that Lorentz violation can also activate multiple polarizations of GWs. We use
the gauge invariants to investigate the polarizations of GWs in the bumblebee
gravity model, and obtain the following results. (i) For a vector background
$b^\mu$ with only a nonzero temporal component $b^t$, there are five
independent propagating degrees of freedom (DOFs), which is simlar to the
Einstein-aether theory. (ii) The presence of a spatial component in the
background defines a preferred spatial direction which breaks rotational
symmetry. We denote $\hat{\bf b}$ as the direction of the spatial part of the
background and $b_s$ as its length. If GWs propagate along $\hat{\bf b}$, the
polarization content is similar to the purely timelike case. (iii) If the
propagation direction of GWs is separated by an angle $\beta$ to $\hat{\bf b}$,
and $\beta=\arccos(b^t/b_s)$, there are only two tensor polarizations. (iv) If
$\beta\neq \arccos(b^t/b_s)$, there are only two independent DOFs, and the
vector and scalar modes degenerate with the tensor modes. The tensor
perturbations can activate a mixture of all six polarizations simultaneously.
Finally, we point out the difference in GWs between the bumblebee gravity model
and the minimal Standard-Model Extension framework in the linearized regime.
Current observations have placed stringent constraints on the anisotropy
induced by the background, while our theoretical study still reveals some novel
phenomena and provides more understanding about the interaction between the
Lorentz-violating vector field and gravity.",2207.14423v2
2022-08-04,Measurement of the $\mathrm{t\bar{t}}$ charge asymmetry in events with highly Lorentz-boosted top quarks in pp collisions at $\sqrt{s}$ = 13 TeV,"The measurement of the charge asymmetry in top quark pair events with highly
Lorentz-boosted top quarks decaying to a single lepton and jets is presented.
The analysis is performed using proton-proton collisions at $\sqrt{s}$ = 13 TeV
with the CMS detector at the LHC and corresponding to an integrated luminosity
of 138 fb$^{-1}$. The selection is optimized for top quarks produced with large
Lorentz boosts, resulting in nonisolated leptons and overlapping jets. The top
quark charge asymmetry is measured for events with a $\mathrm{t\bar{t}}$
invariant mass larger than 750 GeV and corrected for detector and acceptance
effects using a binned maximum likelihood fit. The measured top quark charge
asymmetry of (0.42 $_{-0.69}^{+0.64}$)% is in good agreement with the standard
model prediction at next-to-next-to-leading order in quantum chromodynamic
perturbation theory with next-to-leading-order electroweak corrections. The
result is also presented for two invariant mass ranges, 750-900 and $\gt$ 900
GeV.",2208.02751v2
2022-08-22,Emergent $U(1)$ Symmetries and $τ$-$σ$ Duality in Gapless Superfluids or Superconductors,"A superfluid spontaneously breaks the usual $U(1)$ symmetry because of
condensation. In this article, we illustrate six classes of emergent $U(1)$
symmetries naturally appear in infrared limits in a broad class of gapless
topological superfluids (that either belong to a stable phase or are quantum
critical). In gapless states we have considered, emergent $U(1)$ symmetry
groups are embedded in an $Spin(4)=SU(2) \otimes SU(2)$ group that are
algebraically isomorphic to an $SO(4)$ group. All $U(1)$ charges associated
with symmetries are further invariant under an $SU(2)$ spin group or an
equivalent of it but always break pre-existing higher space-time Lorentz
symmetry of $SO(3,1)$ group. Emergent $U(1)$ symmetries can be further
spontaneously broken only if interactions are strong enough and resultant
strong coupling states become fully gapped. However if states remain gapless,
emergent $U(1)$ symmetries are always present, despite that these states may
exhibit much lower space-time symmetries compared to their weakly interacting
gapless Lorentz symmetric counter parts. In the limit of our interests, we have
identified all possible gapless real fermions with or without Lorentz
symmetries and find that they all display emergent $U(1)$ symmetries in the
infrared limit.We argue emergent $U(1)$ symmetries in infrared are intrinsic in
a broad class of interacting gapless superfluid or superconducting states and
are typically well defined in high dimensions where there are infrared stable
fixed points dictating emergent properties.",2208.10486v2
2022-09-13,Köthe-Herz Spaces: The Amalgam-Type Spaces of Infinite Direct Sums,"In this paper, we introduce a class of function spaces called K\""othe-Herz
spaces $E(\mathcal{X})$. These spaces are similar to amalgam spaces and are
characterized by a local component given by a countable family
$\mathcal{X}=\left( X_{\alpha }\right) _{\alpha \in I}$ of quasi-normed
function spaces, and a global component $E$, which is a quasi-normed sequence
space. We investigate various geometric and topological properties inherited by
$E(\mathcal{X})$ from its components, such as their completeness, duality,
order continuity, ideal and Fatou properties, in an abstract setting. In
addition, we provide a Banach function space characterization for
$E(\mathcal{X})$, which allows us to understand its structure and behavior more
deeply. Furthermore, by appropriate amalgamation of Lorentz spaces (Orlicz
spaces) and Lebesgue sequence spaces, we define Lorentz-Herz spaces
(Orlicz-Herz spaces) as a particular case of $E(\mathcal{X})$, which are still
generalizations of the classical Herz spaces. In this context (especially
Lorentz-Herz spaces), we establish previously studied properties, demonstrate
interpolation results, and prove the boundedness of important sublinear
integral operators with kernels that satisfy a size condition.",2209.05897v4
2022-10-10,Relativistic Gas: Invariant Lorentz Distribution for the velocities,"In 1911, J\""uttner proposed the generalization, for a relativistic gas, of
the Maxwell-Boltzmann distribution of velocities. Here we want to discuss,
among others, J\""uttner probability density function (PDF). Both the velocity
space and, consequently, the momentum space are not flat in special relativity.
The velocity space corresponds to the Lobachevsky one, which has a negative
curvature. This curvature induces a specific power for the Lorentz factor in
the PDF, affecting J\""uttner normalization constant in one, two, and three
dimensions. Furthermore, J\""uttner distribution, written in terms of a more
convenient variable, the rapidity, presents a curvature change at the origin at
sufficiently high energy, which does not agree with our computational dynamics
simulations of a relativistic gas. However, in one dimension, the rapidity
satisfies a simple additivity law. This allows us to obtain, through the
Central Limit Theorem, a new, Lorentz-invariant, PDF whose curvature at the
origin does not change for any energy value and which agrees with our
computational dynamics simulations data. Also, we perform extensive
first-principle simulations of a one-dimensional relativistic gas constituted
by light and heavy particles.",2210.05032v2
2022-10-12,Optical measurement of superluminal motion in the neutron-star merger GW170817,"The afterglow of the binary neutron star merger GW170817 gave evidence for a
structured relativistic jet and a link between such mergers and short gamma-ray
bursts. Superluminal motion, found using radio very long baseline
interferometry (VLBI), together with the afterglow light curve provided
constraints on the viewing angle (14-28 degrees), the opening angle of the jet
core (less than about 5 degrees), and a modest limit on the initial Lorentz
factor of the jet core (more than 4). Here we report on another superluminal
motion measurement, at seven times the speed of light, leveraging Hubble Space
Telescope precision astrometry and previous radio VLBI data of GW170817. We
thereby obtain a unique measurement of the Lorentz factor of the wing of the
structured jet, as well as substantially improved constraints on the viewing
angle (19-25 degrees) and the initial Lorentz factor of the jet core (more than
40).",2210.06568v1
2022-10-20,Possible Evidence for Lorentz Invariance Violation in Gamma-ray Burst 221009A,"The preliminary detections of the gamma-ray burst 221009A up to 18 TeV by
LHAASO and up to 251 TeV by Carpet 2 have been reported through Astronomer's
Telegrams and Gamma-ray Coordination Network circulars. Since this burst is at
redshift $z=0.1505$, these photons may at first seem to have a low probability
to avoid pair production off of background radiation fields and survive to
reach detectors on Earth. By extrapolating the reported $0.1-1.0$\ GeV LAT
spectrum from this burst to higher energies and using this to limit the
intrinsic spectrum of the burst, we show that the survival of the 18 TeV photon
detected by LHAASO is not unlikely with many recent extragalactic background
light models, although the detection of a 251 TeV event is still very unlikely.
This can be resolved if Lorentz invariance is violated at an energy scale
$E_{\rm QG}< 49 E_{\rm Planck}$\ in the linear ($n=1$) case, and $E_{\rm QG}<
10^{-6}E_{\rm Planck}$\ in the quadratic ($n=2$) case (95\% confidence limits),
where $E_{\rm Planck}$ is the Planck energy. This could potentially be the
first evidence for subluminal Lorentz invariance violation.",2210.11261v2
2022-11-03,Expected Signature For the Lorentz Invariance Violation Effects on $γ-γ$ Absorption,"There are still some {significant and} unanswered questions about the
{incredible} {very high energy (VHE)} $\gamma$-ray signatures. To help
understand the mechanism, focusing on the linear and quadratic perturbation
mode for the subluminal regime, the present paper revisited the expected
signature for the Lorentz invariance violation effects on $\gamma-\gamma$
absorption in TeV spectra of Gamma-ray bursts (GRBs). We note that there is {a
critical energy} for the pair production process, which is sensitive to the
assumed quantum gravity energy scale. We suggest that a {reemergence of the
energy spectrum of $\gamma$-rays} at the several tens of TeV is a rough
observational diagnostic for the Lorentz invariance violation (LIV) effects.
The expected spectra characteristics are applied to a GRB 221009A. The results
show that the cosmic opacity with LIV effects considered here {can} roughly
reproduce the observed $\gamma$-ray spectra for the source, which enabled us to
constrain the upper limit of the values of energy scale at $E_{\rm
QG,~1}\leq3.35\times10^{20}$ GeV for the linear perturbation and $E_{\rm
QG,~2}\leq9.19\times10^{12}$ GeV for the quadratic perturbation. {These
scenarios would update the bound of the LIV coefficient with $\xi_{\rm
1}^{\prime}\geq 3.62\times10^{-2}$ for the linear perturbation, and $\xi_{\rm
2}^{\prime}\geq 1.33\times10^{6}$ for the quadratic perturbation in the
standard model extension (SME) framework, respectively. }",2211.01836v3
2022-11-07,Spin 1/2 from Gluons,"The theta vacuum in QCD is the standard vacuum, twisted by the exponential of
the Chern-Simons term. But what is the quantum operator $U(g)$ for winding
number $1$?
  We construct $U(g)$ in this note. The Poincare' rotation generators commute
with it only if they are augmented by the spin 1/2 representation of the
Lorentz group coming from large gauge transformations. This result is analogous
to the 'spin-isopin' mixing result due to Jackiw and Rebbi [1], and Hasenfratz
and 't Hooft[2] and a similar result in fuzzy physics [3].
  Hence states can drastically affect representations of observables. This fact
is further shown by charged states dressed by infrared clouds. Following Mund,
Rehren and Schroer [4], we find that Lorentz invariance is spontaneously broken
in these sectors. This result has been extended earlier to QCD (references [15]
given in the Final Remarks) where even the global QCD group is shown to be
broken.
  It is argued that the escort fields of [4] are the Higgs fields for Lorentz
and colour breaking. They are string-localised fields where the strings live in
a union of de Sitter spaces. Their oscillations and those of the infrared
clouds generate the associated Goldstone modes.",2211.03692v5
2022-11-23,Is there a Dynamic Difference between Stealthy and Standard CMEs?,"Stealthy Coronal Mass Ejections (CMEs), lacking low coronal signatures, may
result in significant geomagnetic storms. However, the mechanism of stealthy
CMEs is still highly debated. In this work, we investigate whether there are
differences between the stealthy and standard CMEs in terms of their dynamic
behaviors. Seven stealthy and eight standard CMEs with slow speeds are
selected. We calculate two-dimensional speed distributions of CMEs based on the
cross-correlation method, rather than the unidimensional speed, and further
obtain more accurate distributions and evolution of CME mechanical energies.
Then we derive the CME driving powers and correlate them with CME parameters
(total mass, average speed, and acceleration) for standard and stealthy CMEs.
Besides, we study the forces that drive CMEs, namely, the Lorentz force,
gravitational force, and drag force due to the ambient solar wind near the Sun.
The results reveal that both the standard and stealthy CMEs are propelled by
the combined action of those forces in the inner corona. The drag force and
gravitational force are comparable with the Lorentz force. However, the impact
of the drag and Lorentz forces on the global evolution of the stealthy CMEs is
significantly weaker than that of the standard CMEs.",2211.12825v1
2022-12-09,Probing Lorentz-violating electrodynamics with CMB polarization,"We perform a comprehensive study of the signatures of Lorentz violation in
electrodynamics on the Cosmic Microwave Background (CMB) anisotropies. In the
framework of the minimal Standard Model Extension (SME), we consider effects
generated by renormalizable operators, both CPT-odd and CPT-even. These
operators are responsible for sourcing, respectively, cosmic birefringence and
circular polarization. We propagate jointly the effects of all the relevant
Lorentz-violating parameters to CMB observables and provide constraints with
the most recent CMB datasets. We bound the CPT-even coefficient to $k_{F,E+B} <
2.31 \times 10^{-31}$ at 95\% CL. This improves previous CMB bounds by one
order of magnitude. The limits we obtain on the CPT-odd coefficients, i.e.
$|k_{(V)00}^{(3)}| < 1.54 \times 10^{-44} \; {\rm GeV}$ and $|\mathbf{k_{AF}}|
< 0.74 \times 10^{-44} \; {\rm GeV}$ at 95\% CL, are respectively one and two
orders of magnitude stronger than previous CMB-based limits, superseding also
bounds from non-CMB searches. This analysis provides the strongest constraints
to date on CPT-violating coefficients in the minimal SME from CMB searches.",2212.04867v2
2023-01-03,Transverse circular photogalvanic effect associated with Lorentz-violating Weyl fermions,"Nonlinear optical responses of quantum materials have recently undergone
dramatic developments to unveil nontrivial geometry and topology. A remarkable
example is the quantized longitudinal circular photogalvanic effect (CPGE)
associated with the Chern number of Weyl fermions, while the physics of
transverse CPGE in Weyl semimetals remains exclusive. Here, we show that the
transverse CPGE of Lorentz invariant Weyl fermions is forced to be zero. We
find that the transverse photocurrents of Weyl fermions are associated not only
with the Chern numbers but also with the degree of Lorentz-symmetry breaking in
condensed matter systems. Based on the generic two-band model analysis, we
provide a new powerful equation to calculate the transverse CPGE based on the
tilting and warping terms of Weyl fermions. Our results are more capable in
designing large transverse CPGE of Weyl semimetals in experiments and are
applied to more than tens of Weyl materials to estimate their photocurrents.
Our method paves the way to study the CPGE of massless or massive
quasiparticles to design next-generation quantum optoelectronics.",2301.00958v1
2023-01-30,Does Deconfined Quantum Phase Transition Have to Keep Lorentz Symmetry? Two Velocities of Spinon and String,"Lorentz symmetry is commonly assumed to be an intrinsic requirement of the
(2+1)d deconfined quantum phase transition (DQPT), and the conformal field
theory (CFT) can be utilized. The dynamics of DQPT in the Kagome lattice are
explored by using a combination of large-scale quantum Monte Carlo simulations
and stochastic analytic continuation. In the valence-bonded solid phase, the
fragmentation of a nearly flat band with a finite energy gap is observed around
the K point. At the deconfined quantum critical point, besides the linear
dispersion at the $\Gamma$ point, another one is found at the K point.
Counterintuitively, these two gapless modes take different speeds equal to
0.319(8) and 0.101(9), indicating the absence of Lorentz symmetry. After
carefully inspecting the snapshot of the simulation, we discovered the fast
mode at $\Gamma$ point corresponding to the deconfinement of spinons
(fractional charges), and the slow mode at K point is related to the quantum
string ( generalized symmetry). Our work will extend the understanding of phase
transition, and intrigue the field of topological quantum field theory.",2301.12864v1
2023-02-06,A microscopic analogue of the BMS group,"We consider a microscopic analogue of the BMS analysis of asymptotic
symmetries by analysing universal geometric structures on infinitesimal tangent
light cones. Thereby, two natural microscopic symmetry groups arise: A
non-trivially represented Lorentz group and a BMS-like group. The latter has a
rich mathematical structure, since it contains the former as a non-canonical
subgroup, next to infinitely many other Lorentz subgroups. None of those
Lorentz subgroups appears to be intrinsically preferred, and hence, the
microscopic BMS-like group constitutes a natural symmetry group for
infinitesimal tangent light cones. We compare our investigation with the
classical BMS analysis and show, that the microscopic BMS-like group is a gauge
group for the bundle of null vectors. Motivated by the various applications of
the original BMS group, our findings could have interesting implications: They
identify a geometric structure that could be suitable for a bulk analysis of
gravitational waves, they suggest a possible enlargement of the fundamental
gauge group of gravity and they motivate the possibility of an interrelation
between the UV structure of gauge theories, gravitational memory effects and
BMS-like symmetries. Also, our results imply, that BMS-like groups arise not
only as macroscopic, asymptotic symmetry groups in cosmology, but describe also
a fundamental and seemingly unknown microscopic symmetry of pseudo-Riemannian
geometry.",2302.03111v3
2023-02-08,A Lorentz-violating low-energy model for the bilayer Graphene,"In this work, we propose a model with Lorentz symmetry violation which
describes the electronic low energy limit of the AA-bilayer graphene (BLG)
system. The AA-type bilayer is known to preserve the linear dispersion relation
of the graphene layer in the low energy limit. The theoretical model shows that
in the BLG system, a time-like vector can be associated with the layer
separation and contributes to the energy eigenstates. Based on these
properties, we can describe in a $(2+1)$-dimensional space-time the fermionic
quasi-particles that emerge in the low-energy limit with the introduction of a
Lorentz-violating parameter, in analogy with the $(3 + 1)$-dimensional Standard
Model Extension (SME). Moreover, we study the consequences of the coupling of
these fermionic quasi-particles with the electromagnetic field, and we show via
effective action that the low-energy photon acquires a massive spectrum.
Finally, using the hydrodynamic approach in the collisionless limit, one finds
that the LSV generates a new kind of anomalous thermal current to the vortexes
of the system via coupling of the LSV vector.",2302.04327v2
2023-03-22,Dark matter spike around Bumblebee black holes,"The effects of dark matter spike in the vicinity of the supermassive black
hole, located at the center of M87 (the Virgo A galaxy), are investigated
within the framework of the so-called Bumblebee Gravity. Our primary aim is to
determine whether the background of spontaneous Lorentz symmetry breaking has a
significant effect on the horizon, ergo-region, and shadow of the Kerr
Bumblebee black hole in the spike region. For this purpose, we first
incorporate the dark matter distribution in a Lorentz-violating spherically
symmetric space-time as a component of the energy-momentum tensors in the
Einstein field equations. This leads to a space-time metric for a Schwarzschild
Bumblebee black hole with a dark matter distribution in the spike region and
beyond. Subsequently, this solution is generalized to a Kerr Bumblebee black
hole through the use of the Newman-Janis-Azreg-A\""inou algorithm. Then,
according to the available observational data for the dark matter spike density
and radius, and the Schwarzschild radius of the supermassive black hole in
Virgo A galaxy, we examine the shapes of shadow and demonstrate the influence
of the spin parameter $a$, the Lorentz-violating parameter $\ell$ and the
corresponding dark matter halo parameters $\rho_{0}$ and $r_{0}$ on the
deformation and size of the shadow.",2303.13554v4
2023-04-03,Analysis of Metallic Space-Time Gratings using Lorentz Transformations,"This paper presents an analytical framework for the study of scattering and
diffraction phenomena in spacetime-modulated metallic gratings. Using a Lorentz
transformation, it is shown that a particular class of spacetime-modulated
gratings behave effectively as moving media. We take advantage of this property
to derive a closed analytical solution for the wave scattering problem. In
particular, using our formalism it is possible to avoid spacetime Floquet-Bloch
expansions, as the solution of the problem in the original laboratory frame
(grating parameters are periodic in space and time) is directly linked to a
co-moving frame where the metallic grating is time-invariant (grating
parameters are periodic only in space). In this way, we identify a fundamental
connection between moving metallic gratings and spacetime-modulated
metamaterials, and exploit this link to study the nonreciprocal response of the
structure. Some limitations and difficulties of the alternative nonrelativistic
Galilean approach are discussed and the benefits of the Lorentz approach are
highlighted. Finally, some analytical results are presented in order to
validate the formalism. The results include scenarios involving TM(p) and TE(s)
normal and oblique incidence, even beyond the onset of the diffraction regime.
Furthermore, we show how the synthetic Fresnel drag can tailor the
Goos-H\""anchen effect and create a specular point shifted towards the direction
of the synthetic motion, independent of the sign of the incidence angle.",2304.01307v2
2023-05-18,Probing the Lorentz Invariance Violation via Gravitational Lensing and Analytical Eigenmodes of Perturbed Slowly Rotating Bumblebee Black Holes,"The ability of bumblebee gravity models to explain dark energy, which is the
phenomenon responsible for the universe's observed accelerated expansion, is
one of their most significant applications. An effect that causes faster
expansion can be linked to how much the Lorentz symmetry of our universe is
violated. Moreover, since we do not know what generates dark energy, the
bumblebee gravity theory seems highly plausible. By utilizing the physical
changes happening around a rotating bumblebee black hole (RBBH), we aim to
obtain more specific details about the bumblebee black hole's spacetime and our
universe. However, as researched in the literature, slow-spinning RBBH (SRBBH)
spacetime, which has a higher accuracy, will be considered instead of general
RBBH. To this end, we first employ the Rindler--Ishak method (RIM), which
enables us to study how light is bent in the vicinity of a gravitational lens.
We evaluate the deflection angle of null geodesics in the equatorial plane of
the SRBBH spacetime. Then, we use astrophysical data to see the effect of the
Lorentz symmetry breaking (LSB) parameter on the bending angle of light for
numerous astrophysical stars and black holes. We also acquire the analytical
greybody factors (GFs) and quasinormal modes (QNMs) of the SRBBH. Finally, we
visualize and discuss the results obtained in the conclusion section.",2305.10815v1
2023-06-01,On stability of solitons for 3D Maxwell-Lorentz equations with spinning particle,"We consider stability of solitons of 3D Maxwell--Lorentz system with extended
charged spinning particle.The solitons are solutions which correspond to a
particle moving with a constant velocity $v\in\R^3$ with $|v|<1$ and rotating
with a constant angular velocity $\omega\in R^3$.
  Our main results are the orbital stability of moving solitons with $\omega=0$
and a {\it linear} orbital stability of rotating solitons with $v=0$.
  The Hamilton--Poisson structure of the Maxwell--Lorentz system is degenerate
and admits the Casimir invariants. We construct the Lyapunov function as a
linear combination of the Hamiltonian with a suitable Casimir invariant. The
key point is a lower bound for this function. The proof of the bound in the
case $\om\ne 0$ relies on angular momentum conservation and suitable spectral
arguments including the Heinz inequality and closed graph theorem.",2306.00508v9
2023-07-09,Relativistic time dilation from a quantum mechanism,"One of the concepts of Relativity theory that challenges conventional
intuition the most is time dilation and length contraction. Usual approaches
for describing relativistic effects in quantum systems merely postulate the
consequences of these effects as physical constraints. Here, we propose to
rebuild Special Relativity from quantum mechanical considerations. This is done
by dropping one of its fundamental postulates: the universality of the speed of
light. Lorentz transformations are obtained by a quantum mechanism. We use the
fact that quantum states depend on the Galilean reference frame where they are
defined. In other words, quantum states outside an observer's Galilean
reference frame are distorted. Then, we show in a theorem the existence of
time-dependent observables that are sensible to this distortion in such a way
that their expectation value is a Lorentz-covariant function of time. We then
postulate this mechanism as the source of the phenomena of Special Relativity.
As a corollary of the main theorem, we show the existence of a Lorentz
covariant momentum and mass operators which yield the relativistic momentum and
mass. In this theory, the fundamental limit of the speed of light imposes a
transparency condition for faster-than-light particles: they are allowed but
they are not observable. The transparency effect could explain dark matter in a
more general theory following this quantum formalism.",2307.04254v4
2023-07-24,Measuring Gravitational Wave Speed and Lorentz Violation with the First Three Gravitational-Wave Catalogs,"The speed of gravitational waves $v_g$ can be measured with the time delay
between gravitational-wave detectors. Our study provides a more precise
measurement of $v_g$ using gravitational-wave signals only, compared with
previous studies. We select 52 gravitational-wave events that were detected
with high confidence by at least two detectors in the first three observing
runs (O1, O2, and O3) of Advanced LIGO and Advanced Virgo. We use Markov chain
Monte Carlo and nested sampling to estimate the $v_g$ posterior distribution
for each of those events. We then combine their posterior distributions to find
the 90% credible interval of the combined $v_g$ distribution for which we
obtain $0.99^{+0.02}_{-0.02}c$ without the use of more accurate sky
localization from the electromagnetic signal associated with GW170817.
Restricting attention to the 50 binary black hole events generates the same
result, while the use of the electromagnetic sky localization for GW170817
gives a tighter constraint of $0.99^{+0.01}_{-0.02}c$. The abundance of
gravitational wave events allows us to apply hierarchical Bayesian inference on
the posterior samples to simultaneously constrain all nine coefficients for
Lorentz violation in the nondispersive, nonbirefringent limit of the
gravitational sector of the Standard-Model Extension test framework. We compare
the hierarchical Bayesian inference method with other methods of combining
limits on Lorentz violation in the gravity sector that are found in the
literature.",2307.13099v1
2023-08-02,Lorentz invariant polynomials as entanglement indicators for Dirac particles,"The spinorial degrees of freedom of two or more spacelike separated Dirac
particles are considered and a method for constructing mixed polynomials that
are invariant under the spinor representations of the local proper
orthochronous Lorentz groups is described. The method is an extension of the
method for constructing homogeneous polynomials introduced in [Phys. Rev. A
105, 032402 (2022), arXiv:2103.07784] and [Ann. Phys. (N. Y.) 457, 169410
(2023), arXiv:2105.07503]. The mixed polynomials constructed by this method are
identically zero for all product states. Therefore they are considered
indicators of the spinor entanglement of Dirac particles. Mixed polynomials can
be constructed to indicate spinor entanglement that involves all the particles,
or alternatively to indicate spinor entanglement that involves only a proper
subset of the particles. It is shown that the mixed polynomials can indicate
some types of spinor entanglement that involves all the particles but cannot be
indicated by any homogeneous locally Lorentz invariant polynomial. For the case
of two Dirac particles mixed polynomials of bidegree (2,2) and bidegree (3,1)
are constructed. For the case of three Dirac particles mixed polynomials of
bidegree (2,2), bidegree (3,1) and bidegree (3,3) are constructed. The
relations of the polynomials constructed for two and three Dirac particles to
the polynomial spin entanglement indicators for two and three non-relativistic
spin-$\frac{1}{2}$ particles are described. Moreover, the constructed
polynomial indicators of spinor entanglement are in general not invariant under
local time evolutions of the particles but evolve dynamically and we discuss
how to describe this dynamical evolution.",2308.00896v1
2023-08-13,Optically thick jet base and explanation of edge brightening in AGN jets,"The jet cores in blazars are resolved and found to harbour an edge brightened
structure where the jet base appears extended at sides compared to its
propagation axis. This peculiar phenomenon invites various explanations. We
show that the photosphere of an optically thick jet base in Active Galactic
Nuclei (AGNs) is observed edge brightened if the jet Lorentz factor harbours an
angular dependence. The jet assumes a higher Lorentz factor along the jet axis
and decreases following a power law along its polar angle. For an observer near
the jet axis, the jet has a lower optical depth along its propagation axis
compared to off axis regions. Higher optical depths at the outer region makes
the jet photosphere appear to extend to larger radii compared to a deeper
photosphere along its propagation axis. We tackle the problem both analytically
and numerically, confirming the edge brightening through Monte Carlo
simulations. Other than the edge brightening, the outcomes are significant as
they provide a unique tool to determine the jet structure and associated
parameters by their resolved observed cores. The study paves way to explore the
spectral properties of optically thick cores with structured Lorentz factors in
the future.",2308.06728v1
2023-08-22,Radiative Magnetohydrodynamic Simulation of the Confined Eruption of a Magnetic Flux Rope: Unveiling the Driving and Constraining Forces,"We analyse the forces that control the dynamic evolution of a flux rope
eruption in a three-dimensional (3D) radiative magnetohydrodynamic (RMHD)
simulation. The confined eruption of the flux rope gives rise to a C8.5 flare.
The flux rope rises slowly with an almost constant velocity of a few km/s in
the early stage, when the gravity and Lorentz force are nearly counterbalanced.
After the flux rope rises to the height at which the decay index of the
external poloidal field satisfies the torus instability criterion, the
significantly enhanced Lorentz force breaks the force balance and drives rapid
acceleration of the flux rope. Fast magnetic reconnection is immediately
induced within the current sheet under the erupting flux rope, which provides a
strong positive feedback to the eruption. The eruption is eventually confined
due to the tension force from the strong external toroidal field. Our results
suggest that the gravity of plasma plays an important role in sustaining the
quasi-static evolution of the pre-eruptive flux rope. The Lorentz force, which
is contributed from both the ideal magnetohydrodynamic (MHD) instability and
magnetic reconnection, dominates the dynamic evolution during the eruption
process.",2308.11271v1
2023-10-19,Generalized Parton Distributions from Lattice QCD with Asymmetric Momentum Transfer: Axial-vector case,"Recently, we made significant advancements in improving the computational
efficiency of lattice QCD calculations for Generalized Parton Distributions
(GPDs). This progress was achieved by adopting calculations of matrix elements
in asymmetric frames, deviating from the computationally-expensive symmetric
frame typically used, and allowing freedom in the choice for the distribution
of the momentum transfer between the initial and final states. A crucial aspect
of this approach involves the adoption of a Lorentz covariant parameterization
for the matrix elements, introducing Lorentz-invariant amplitudes. This
approach also allows us to propose an alternative definition of quasi-GPDs,
ensuring frame independence and potentially reduce power corrections in
matching to light-cone GPDs. In our previous work, we presented lattice QCD
results for twist-2 unpolarized GPDs ($H$ and $E$) of quarks obtained from
calculations performed in asymmetric frames at zero skewness. Building upon
this work, we now introduce a novel Lorentz covariant parameterization for the
axial-vector matrix elements. We employ this parameterization to compute the
axial-vector GPD $\widetilde{H}$ at zero skewness, using an $N_f=2+1+1$
ensemble of twisted mass fermions with clover improvement. The light-quark
masses employed in our calculations correspond to a pion mass of approximately
260 MeV.",2310.13114v2
2023-11-27,"T-Minkowski noncommutative spacetimes I: Poincaré groups, differential calculi and braiding","This paper introduces and investigates a class of noncommutative spacetimes
that I will call ``T-Minkowski,'' whose quantum Poincar\'e group of isometries
exhibits unique and physically motivated characteristics. Notably, the
coordinates on the Lorentz subgroup remain commutative, while the deformation
is confined to the translations (hence the T in the name), which act like an
integrable set of vector fields on the Lorentz group. This is similar to
Majid's bicrossproduct construction, although my approach allows the
description of spacetimes with commutators that include a constant matrix as
well as terms that are linear in the coordinates (the resulting structure is
that of a centrally-extended Lie algebra). Moreover, I require that one can
define a covariant braided tensor product representation of the quantum
Poincar\'e group, describing the algebra of N-points. This also implies that a
4-dimensional bicovariant differential calculus exists on the noncommutative
spacetime. The resulting models can all be described in terms of a numerical
triangular R-matrix through RTT relations (as well as RXX, RXY and RXdX
relations for the homogeneous spacetime, the braiding and the differential
calculus). The R-matrices I find are in one-to-one correspondence with the
triangular r-matrices on the Poincar\'e group without quadratic terms in the
Lorentz generators. These have been classified, up to automorphisms, by
Zakrzewski, and amount to 16 inequivalent models. This paper is the first of
two, focusing on the identification of all the quantum Poincar\'e groups that
are allowed by my assumptions, as well as the associated quantum homogeneous
spacetimes, differential calculi and braiding constructions.",2311.16249v1
2024-02-03,Rotating Black Holes in a Viable Lorentz-Violating Gravity: Finding Exact Solutions Without Tears,"We introduce a two-step procedure for finding Kerr-type rotating black hole
solutions without tears. Considering the low-energy sector of Horava gravity as
a viable Lorentz-violating gravity in four dimensions which admits a different
speed of gravity, we find the exact rotating black hole solutions (with or
without cosmological constant). We find that the singular region extends to r <
0 region from the ring singularity at r = 0 in Boyer-Lindquist coordinates.
There are two Killing horizons where g^rr = 0 and the black hole thermodynamics
laws are still valid. We find the rotating black hole solutions with
electromagnetic charges only when we consider the noble electromagnetic
couplings, in such a way that the speed of light is the same as the speed of
gravity. With the noble choice of couplings, our Lorentz-violating gravity can
be consistent with the recently-observed time delay of the coincident GW and
GRB signals. Furthermore, in Appendices, we show that (a) the uniqueness of the
invariant line element ds^2 under Diff_F, contrary to LV action, (b) the
solutions are the Petrov type I with four distinct principal null vectors, and
(c) the Hamilton-Jacobi equation for the geodesic particles are not separable.",2402.02253v1
2024-03-28,The Lorentz force at work: multi-phase magnetohydrodynamics throughout a flare lifespan,"The hour-long, gradual phase of solar flares is well-observed across the
electromagnetic spectrum, demonstrating many multi-phase aspects, where cold
condensations form within the heated post-flare system, but a complete
three-dimensional (3D) model is lacking. Using a state-of-the-art 3D
magnetohydrodynamic simulation, we identify the key role played by the Lorentz
force through the entire flare lifespan, and show that slow variations in the
post-flare magnetic field achieve the bulk of the energy release. Synthetic
images in multiple passbands closely match flare observations, and we quantify
the role of conductive, radiative and Lorentz force work contributions from
flare onset to decay. This highlights how the non-force-free nature of the
magnetic topology is crucial to trigger Rayleigh-Taylor dynamics, observed as
waving coronal rays in extreme ultraviolet observations. Our C-class solar
flare reproduces multi-phase aspects such as post-flare coronal rain. In
agreement with observations, we find strands of cooler plasma forming
spontaneously by catastrophic cooling, leading to cool plasma draining down the
post-flare loops. As there is force balance between magnetic pressure and
tension and the plasma pressure in gradual-phase flare loops, this has
potential for coronal seismology to decipher the magnetic field strength
variation from observations.",2403.19204v1
1996-09-10,"Selfacceleration of Electrons in One-dimensional Bunches, Moving in Cold Plasma","Nonlinear dynamics of the one-dimensional ultrarelativistic bunch of
electrons,moving in cold plasma,is considered in multiple scales perturbative
approach. A square root of the inverse Lorentz factor of the bunch electrons is
taken as a small parameter. Bunch electrons momenta is changed in the first
approximation.In the underdense plasma and for the model example of the
combined bunch the selfacceleration of the bunch electrons can be remarkable.",9609003v1
1994-04-20,Gamma Ray Bursts from Interaction of Relativistic Flows with Radiation Fields,"Relativistic flows resulting from sudden explosive events upscatter ambient
interstellar photons of local radiation fields. For Lorentz factor $ > 100$ and
dense optical - UV radiation fields the emergent signal is a typical gamma ray
burst. Presumably the explosions occur in dense globular clusters or in
galactic nuclei, at cosmological distances.",9404047v1
1996-11-25,Constraints on the properties of the 2175 angstrom interstellar feature carrier,"Constraints on the possible shape and clustering, as well as optical
properties, of grains responsible for the 2175 angstrom interstellar extinction
feature (interstellar UV bump) are discussed. These constraints are based on
the observation that the peak position of the interstellar UV feature is very
stable (variations <~1%), that the large variations in width (<~25%) are
uncorrelated with the peak position except for the widest bumps, and that the
shape of the feature is described extremely well by a Drude profile. The UV
extinction of small graphite grains is computed for various clustering models
involving Rayleigh spheres. It is shown that compact clusters qualitatively
satisfy the above observational constraints, except that the peak position
falls at the wrong wavelength. As an alternative to graphite to model the
optical properties of the interstellar UV feature carrier, a single-Lorentz
oscillator model is considered, in conjunction with a clustering model based on
clusters of spheres. Intrinsic changes in the peak position and width are
attributed to variations in chemical composition of the grains, impacting upon
the parameters of the Lorentz oscillator. Further broadening is attributed to
clustering. These models are shown to satisfy the above observational
constraints. Furthermore, the correlated shift of peak position with increased
width, observed for the widest interstellar UV features, is reproduced. Models
involving a second Lorentz oscillator to reproduce the FUV rise are also
considered. The impact of this extra Lorentz oscillator on the peak position,
width, and shape of the bump is investigated. Synthetic extinction curves are
generated to model actual ones exhibiting a wide range of FUV curvatures.
Physical mechanisms which might be of relevance to explain the variations of
these optical properties are discussed.",9611203v1
2003-03-20,Ultrahigh Energy Neutrals from Extreme Magnetic Flares,"It is shown that bulk acceleration during reconnection of extremely strong
magnetic fields near compact objects can accelerate ions to Lorentz factors of
$\sim 10^2 \sigma^{3/5}$ under general conditions, where $\sigma$, the magnetic
energy per current-carrying proton rest energy, can approach $10^{15}$. For
magnetar-type fields, neutrons and neutrinos can be generated at potentially
detectable levels via hadron polarization. Ultrahigh energy photons can also be
emitted and escorted from the high field region by Poynting flux.",0303474v1
2003-11-04,Aberration and the Fundamental Speed of Gravity in the Jovian Deflection Experiment,"We describe our explicit Lorentz-invariant solution of the Einstein and null
geodesic equations for the deflection experiment of 2002 September 8 when a
massive moving body, Jupiter, passed within 3.7' of a line-of-sight to a
distant quasar. We develop a general relativistic framework which shows that
our measurement of the retarded position of a moving light-ray deflecting body
(Jupiter) by making use of the gravitational time delay of quasar's radio wave
is equivalent to comparison of the relativistic laws of the Lorentz
transformation for gravity and light. Because, according to Einstein, the
Lorentz transformation of gravity field variables must depend on a fundamental
speed $c$, its measurement through the retarded position of Jupiter in the
gravitational time delay allows us to study the causal nature of gravity and to
set an upper limit on the speed of propagation of gravity in the near zone of
the solar system as contrasted to the speed of the radio waves. We discuss the
misconceptions which have inhibited the acceptance of this interpretation of
the experiment. We also comment on other interpretations of this experiment by
Asada, Will, Samuel, Pascual-Sanchez, and Carlip and show that their `speed of
light' interpretations confuse the Lorentz transformation for gravity with that
for light, and the fundamental speed of gravity with the physical speed of
light from the quasar.",0311063v6
2003-11-13,Invisible Un-removable Field: A Search by Ultra-High Energy Cosmic Rays,"A Toy model which introduces the different limiting velocities for each
particleis discussed: the differentiation of the universal limiting velocity is
implemented throgh the coupling with external tensor or vector field, something
like Higgs scalar field. GZK cut-off discussion could be altered due to the
violation of Lorentz symmetry.",0311306v1
2006-01-17,From the Foucault pendulum to the galactical gyroscope and LHC,"We consider the Foucault pendulum, isosceles triangle pendulum and the
general triangle pendulum rotating on the Earth. As an analogue, planet
orbiting in the rotating galaxy is considered as the giant galactical
gyroscope. The Lorentz and the Bargman-Michel-Telegdi equations are generalized
for the rotating system. These equations are inevitable for LHC where orbital
photons ""feels"" the Coriolis force caused by the rotation ofthe Earth.",0601365v1
1993-12-05,Transport Properties of the Lorentz Gas in Terms of Periodic Orbits,"We establish a formula relating global diffusion in a space periodic
dynamical system to cycles in the elementary cell which tiles the space under
translations.",9312003v1
1996-12-05,Stability ordering of cycle expansions,"We propose that cycle expansions be ordered with respect to stability rather
than orbit length for many chaotic systems, particularly those exhibiting
crises. This is illustrated with the strong field Lorentz gas, where we obtain
significant improvements over traditional approaches.",9612009v1
1997-02-06,Dynamical stripe correlations and the spin fluctuations in cuprate superconductors,"It is conjectured that the anomalous spin dynamics observed in the normal
state of cuprate superconductors might find its origin in a nearly ordered spin
system which is kept in motion by thermally meandering charged domain walls.
`Temperature sets the scale' finds a natural explanation, while a crossover to
a low temperature quantum domain wall fluid is implied.",9702060v1
1998-01-24,Interference phenomena in radiation of a charged particle moving in a system with one-dimensional randomness,"The contribution of interference effects to the radiation of a charged
particle moving in a medium of randomly spaced plates is considered. In the
angular dependent radiation intensity a peak appears at angles
$\theta\sim\pi-\gamma^{-1}$, where $\gamma$ is the Lorentz factor of the
charged particle.",9801255v1
1998-06-04,Electrodymanics of Moving Continuous Media with Toroid Polarization,"With regard to the toroid contributions, a modified system of equations of
electrodynamics moving continuous media has been obtained. Alternative
formalisms to introduce the toroid moment contributions in the equations of
electromagnetism has been worked out. The two four-potential formalism has been
developed for the electromagnetic continous media subjected to Lorentz
transformations.",9806057v1
1993-11-16,Gravitational Field of a Moving Point Particle,"The gravitational field of a moving point particle is obtained in a Lorentz
covariant form for both uncharged and charged cases. It is shown that the
general relativistic proper time interval at the location of the particle is
the same as the special relativistic one and the gravitational and
electromagnetic self forces are zero.",9311027v1
1994-12-16,Ordinary Matter in Nonlinear Affine Gauge Theories of Gravitation,"We present a general framework to include ordinary fermionic matter in the
metric--affine gauge theories of gravity. It is based on a nonlinear gauge
realization of the affine group, with the Lorentz group as the classification
subgroup of the matter and gravitational fields.",9412045v1
1997-05-21,Universal Spin Structure in Gauge Gravitation Theory,"Building on the universal covering group of the general linear group, we
introduce the composite spinor bundle whose subbundles are Lorentz spin
structures associated with different gravitational fields. General covariant
transformations of this composite spinor bundle are canonically defined.",9705058v1
1997-10-21,Diffeomorphism Invariance of Geometric Descriptions of Palatini and Ashtekar Gravity,"In this paper, we explicitly prove the presymplectic forms of the Palatini
and Ashtekar gravity to be zero along gauge orbits of the Lorentz and
diffeomorphism groups, which ensures the diffeomorphism invariance of these
theories.",9710095v1
1999-01-23,A new look at relativity transformations,"A free system, considered to be a comparison system, allows for the notion of
objective existence and inertial frame. Transformations connecting inertial
frames are shown to be either Lorentz or generalized Galilei.",9901064v1
2000-01-27,On the gravitational moments of a Dirac particle,"We consider the classical theory of the Dirac massive particle in the
Riemann-Cartan spacetime. We demonstrate that the translational and the Lorentz
gravitational moments, obtained by means of the Gordon type decompositions of
the canonical energy-momentum and spin currents, are consistently coupled to
torsion and curvature, as expected.",0001089v1
2000-04-13,Hypergravity and Categorical Feynmanology,"We propose a new line of attack to create a finite quantum theory which
includes general relativity and (perhaps) the standard model in its low energy
limit. The theory would emerge from the categorical approach. A structure is
observed on the category of unitary representations of the lorentz group which
we call hypergravity. This, combined with a study of the relationship between
Feynman diagrams and words in tensor categories, leads to the proposal.",0004043v1
2000-10-12,Angular momentum conservation law in Einstein-Cartan space-time,"In the light of the local Lorentz transformations and the general Noether
theorem, a new formulate of the general covariant angular momentum conservation
law in Einstein-Cartan gravitation theory is obtained, which overcomes the
critical difficulty in the other formulates that the conservation law depended
on the coordinative choice.",0010047v1
2002-07-24,Finslerian Extension of Lorentz Transformations and First-Order Censorship Theorem,"Granted the post-Lorentzian relativistic kinematic transformations are
described in the Finslerian framework, the uniformity between the actual light
velocity anisotropy change and the anisotropic deformation of measuring rods
can be the reason proper for the null results of the Michelson-Morley-type
experiments at the first-order level.",0207089v1
2002-12-03,Spacetime Foam and Vacuum Energy,"A simple model of spacetime foam, made by spherically symmetric wormholes,
with or without a cosmological term is proposed. The black hole area
quantization and its consequences are examined in this context. We open the
possibility of probing Lorentz symmetry in this picture.",0212013v1
2003-06-20,Three Key Tests to Gravity,"Three presumably unrelated open questions concerning gravity and the
structure of the Universe are here discussed: 1) To which extent is Lorentz
invariance an exact symmetry ? 2) What is the equation of state of the Universe
? 3) What is the origin of the so-called Pioneer anomaly ?",0306093v1
2003-10-09,Scalar Field for Breaking Lorentz and Diffeomorphism Invariance,"A scalar field can be inserted in Maxwell and/or Einstein theory to effect
symmetry breaking. Consequences of such a modification are discussed. Possible
dynamics for the scalar field are presented.",0310053v3
2004-01-30,Lorentzian Gromov Hausdorff theory as a tool for quantum gravity kinematics,"This thesis start by a review of different approaches to classical and
quantum gravity. The main theme is Lorentzian Gromov Hausdorff theory which is
an active diffeomorphism invariant theory on the space of Lorentz spaces (think
about globally hyperbolic spacetimes). It is argued why such theory might be of
significant importance for Lorentzian approaches to quantum gravity such as
causal set theory and Lorentzian dynamical triangulations",0401126v1
2004-09-30,Einstein-Aether Theory,"We review the status of ""Einstein-Aether theory"", a generally covariant
theory of gravity coupled to a dynamical, unit timelike vector field that
breaks local Lorentz symmetry. Aspects of waves, stars, black holes, and
cosmology are discussed, together with theoretical and observational
constraints. Open questions are stressed.",0410001v2
2005-06-06,A spacetime realization of kappa-Poincare algebra,"We study a Hamiltonian realization of the phase space of kappa-Poincare
algebra that yields a definition of velocity consistent with the deformed
Lorentz symmetry. We are also able to determine the laws of transformation of
spacetime coordinates and to define an invariant spacetime metric, and discuss
some possible experimental consequences.",0506036v2
2005-12-01,Perspectives on Quantum Gravity Phenomenology,"The idea that quantum gravity manifestations would be associated with a
violation of Lorentz invariance is very strongly bounded and faces serious
theoretical challenges. Other related ideas seem to be drowning in
interpretational quagmires. This leads us to consider alternative lines of
thought for such phenomenological search. We discuss the underlying viewpoints
and briefly mention their possible connections with other current theoretical
ideas.",0512013v1
2006-02-19,Aspects of spacetime-symmetry violations,"The violation of spacetime symmetries provides a promising candidate signal
for underlying physics, possibly arising at the Planck scale. This talk gives
an overview over various aspects in the field, including some mechanisms for
Lorentz breakdown, the SME test framework, and phenomenological signatures for
such effects.",0602073v1
2007-01-21,Schwarzschild Spacetime without Coordinates,"We discuss how to construct the full Schwarzschild (Kruskal-Szekeres)
spacetime in one swoop by using the bundle of orthonormal Lorentz frames and
the Einstein equation without the use of coordinates. We never have to write
down the Kruskal-Szekeres or an equivalent form of the metric.",0701115v2
2003-10-13,Non perturbative study of QCD on a 2+2 anisotropic lattice,"We present preliminary results for a non perturbative determination of the
parameters in the action required to restore Lorentz invariance in long
distance correlators, using the static interquark potential. Comparison with
analytical results is made and further applications are discussed.",0310036v1
2003-12-29,A relativistic invariant scheme for the quantum Klein-Gordon and Dirac fields on the lattice,"We explore the connection between the symmetry transformations and
conservation laws for the Klein-Gordon and Dirac fields on the lattice. The
generators of the space time translations and Lorentz boost (defined on the
lattice) are constants of motion and satisfy the standard commutation
relations.",0312041v1
2004-01-05,Induced representations of Poincare group on the lattice: spin 1/2 and 1 case,"Following standard methods we explore the construction of the discrete
Poincare group, the semidirect product of discrete translations and integral
Lorentz transformations, using the Wigner-Mackey construction restricted to the
momentum and position space on the lattice. The orbit condition, irreducibility
and assimptotic limit are discussed.",0401008v1
1992-09-29,The Vector Equivalence Technique,"We present the Vector Equivalence technique. This technique allows a simple
and systematic calculating of Feynman diagrams involving massive fermions at
the matrix element level. As its name suggests, the technique allows two
Lorentz four-vectors to serve as an equivalent of two external fermions. In
further calculations, traces involving these vectors replace the matrix element
with the external fermions. The technique can be conveniently used for both
symbolic and numeric calculations.",9209293v1
1993-11-11,On the Foundations of Chiral Perturbation Theory,"The properties of the effective field theory relevant for the low energy
structure generated by the Goldstone bosons of a spontaneously broken symmetry
are reexamined. It is shown that anomaly free, Lorentz invariant theories are
characterized by a gauge invariant effective Lagrangian, to all orders of the
low energy expansion. The paper includes a discussion of anomalies and
approximate symmetries, but does not cover nonrelativistic effective theories.",9311274v1
1994-03-28,Heavy Meson Decays into Light Resonances,"We analyse the Lorentz structures of weak decay matrix elements bewteen meson
states of arbitrary spin. Simplifications arise in the transition amplitudes
for a heavy meson decaying into a light one via a Bethe-Salpeter approach which
incorporates heavy quark symmetry. Phenomenological consequences on several
semileptonic, nonleptonic and FCNC induced decays of heavy flavoured mesons are
derived and discussed.",9403372v1
1994-07-07,Relativistic Oscillator Model and Delbrück scattering,"Elastic scattering of photons in a Lorentz-scalar potential via virtual
spin-zero particle-antiparticle pairs (`` Delbr\""uck scattering"") is
considered. An analytic expression for the Delbr\""uck amplitude is found
exactly in case of an oscillator potential. General properties of the amplitude
and its asymptotics are discussed.",9407245v1
1996-07-01,Revisiting the Eichten - Feinberg - Gromes Q \bar{Q} Spin-Orbit Interaction,"Invariant and covariant forms of the quark-antiquark interaction derived by
the method of Eichten and Feinberg are considered. Relations between the
various terms imposed by Lorentz transformation constraints, here called Gromes
relations, are found to exist in neither case. Details of the Gromes relation
proper are reconsidered and inconsistencies found that lead to a violation of
covariance.",9607211v2
1997-06-06,Pion Dynamics at Finite Temperature,"The pion decay constant and mass are computed at low temperature within
Chiral Perturbation Theory to two loops. The effects of the breaking of Lorentz
Symmetry by the thermal equilibrium state are discussed. The validity of the
Gell-Mann Oakes Renner relation at finite temperature is examined.",9706273v1
1997-09-05,Testing CPT Symmetry,"In this talk, I review the possibility that CPT and Lorentz symmetry might be
spontaneously broken in nature by effects originating in a theory beyond the
standard model, and I discuss some existing and future experimental tests.",9709263v1
1998-06-26,Sum Rules and Positivity Constraints on Nucleon Spin Structure,"The spin structure of nucleon at twist 2 and 3 levels is analyzed. The
contribution of quark and gluon spins to nucleon spin are Lorentz invariant,
while it is not sure for orbital angular momentum. The conserved fractional
moments of transversity distribution are considered. The scenario of decoupled
total angular momentum, determined predominantly by the unpolarized scattering,
is discussed.",9806502v1
1998-09-25,Some Questions and Answers About CPT Violation,"Minuscule violations of CPT and Lorentz invariance might arise in an
extension of the standard model as suppressed effects from a more fundamental
theory. In this contribution to the CarruthersFest, I present and answer some
questions about CPT and the possibility of its violation.",9809542v1
1998-09-28,Sensitivity of CPT Tests with Neutral Mesons,"The sensitivity of experiments with neutral mesons to possible indirect CPT
violation is examined. It is shown that experiments conventionally regarded as
equivalent can have CPT reaches differing by orders of magnitude within the
framework of a minimal CPT- and Lorentz-violating extension of the standard
model.",9809572v1
1998-10-15,The Status of CPT,"A short review is given of some theoretical approaches to CPT violation. A
potentially realistic possibility is that small apparent breaking of CPT and
Lorentz symmetry could arise at the level of the standard model from
spontaneous symmetry breaking in an underlying theory. Some experimental
constraints are described.",9810365v1
1999-07-23,The Standard Model and the Generalized Covariant Derivative,"The generalized covariant derivative, that uses both scalar and vector
bosons, is defined. It is shown how a grand unified theory of the Standard
Model can be constructed using a generalized Yang-Mills theory.",9907480v1
2000-08-17,A superformula for neutrinoless double beta decay II: The short range part,"A general Lorentz-invariant parameterization for the short-range part of the
0vBB decay rate is derived. Combined with the long range part already published
this general parameterization in terms of effective B-L violating couplings
allows one to extract the 0vBB limits on arbitrary lepton number violating
theories.",0008182v1
2000-08-24,Synchrotron Production of Photons by a Two-body System,"The power spectrum of the synchrotron radiation generated by the motion of a
two-body charged system in an accelerator is derived in the framework of the
Schwinger source theory. The final formula can be used to verify the Lorentz
length contraction of the two-body system moving in the synchrotron.",0008257v1
2001-01-30,QCD on a transverse lattice,"We present results from a transverse lattice study of low lying mesons.
Special emphasis is put on the issue of Lorentz invariant energy-momentum
dispersion relations for these mesons. The light-cone wave function for the
$\pi$ obtained in this framework is very close to its asymptotic shape.",0101338v1
2001-02-18,Physics Beyond SM at RHIC with Polarized Protons,"The capabilities of RHIC with polarized protons to test the Lorentz structure
of electroweak interactions and also the properties of MSSM Higgs, should it be
discovered, are discussed.",0102220v1
2001-03-01,Covariant Treatment of Neutrino Spin (Flavour) Conversion in Matter under the Influence of Electromagnetic Fields,"Within the recently proposed Lorentz invariant formalism for description of
neutrino spin evolution in presence of an arbitrary electromagnetic fields
effects of matter motion and polarization are considered.",0103015v1
2001-07-10,"Parametric Resonance Amplification of Neutrino Oscillations in Electromagnetic Wave with Varying Amplitude and ""Castle Wall"" Magnetic Field","Within the Lorentz invariant formalizm for description of neutrino evolution
in electromagnetic fields and matter we consider neutrino spin oscillations in
the electromagnetic wave with varying amplitude and in ""castle wall"" magnetic
field. It is shown for the first time that the parametric resonances of
neutrino oscillations in such systems can occur.",0107109v1
2002-04-23,Classification and one loop renormalization of dimension six and eight operators in quantum gluodynamics,"We determine the complete set of independent dimension six and eight Lorentz
scalar operators in Yang-Mills theory for an arbitrary colour group. The
anomalous dimension mixing matrix is determined at one loop.",0204266v1
2002-05-20,Relativistic Treatment of Neutrino Oscillations in Moving Matter,"A review on the Lorentz invariant treatment of neutrino spin and flavour
oscillations in moving and polarized matter is presented. Within this approach
it becomes possible to consider neutrino oscillations in arbitrary
electromagnetic fields. It is also shown that neutrino effective potential in
matter can be significantly changed by relativistic motion of matter.",0205200v1
2002-07-11,Hard thermal loops with a background plasma velocity,"I consider the calculation of the two and three-point functions for QED at
finite temperature in the presence of a background plasma velocity. The final
expressions are consistent with Lorentz invariance, gauge invariance and
current conservation, pointing to a straightforward generalization of the hard
thermal loop formalism to this physical situation. I also give the resulting
expression for the effective action and identify the various terms.",0207146v1
2002-07-30,Precision Studies of Relativity in Electrodynamics,"In this contribution to the proceedings of the 2002 Workshop for Fundamental
Physics in Space, a discussion of recent work on astrophysical and laboratory
tests of Lorentz symmetry in electrodynamics is presented. Stringent
constraints are placed on birefringence of light emitted from galactic and
extragalactic sources. The prospect of precision clock-comparison experiments
utilizing resonant cavities are considered.",0207354v1
2003-03-24,Infrared regularization with spin-3/2 fields,"We present a Lorentz-invariant formulation of baryon chiral perturbation
theory including spin-3/2 fields. Particular attention is paid to the
projection on the spin-3/2 components of the delta fields. We also discuss the
nucleon mass and the pion-nucleon sigma term.",0303198v1
2003-08-01,Power counting in baryon chiral perturbation theory including vector mesons,"It is demonstrated that using a suitable renormalization condition one
obtains a consistent power counting in manifestly Lorentz-invariant baryon
chiral perturbation theory including vector mesons as explicit degrees of
freedom.",0308006v1
2004-03-04,Relativistic Effects in the Electromagnetic Structure of $ρ$-meson,"The relativistic calculations of the electromagnetic form factors and static
moments of $\rho$-meson are given in the framework of the relativistic
Hamiltonian dynamics with different model wave functions. The impulse
approximation is used. Lorentz covariance and conservation law for the
electromagnetic current operator are taken into account.",0403046v1
2004-07-21,Testing Relativity with Orbiting Oscillators,"Clock-comparison experiments using a satellite platform can give Planck-scale
sensitivity to many parameters for Lorentz and CPT violation that are difficult
to measure on Earth. A discussion of the theoretical framework for such tests
is given, with emphasis on comparisons of output frequencies of atomic clocks
and of electromagnetic cavity oscillators.",0407256v1
2004-12-22,Spacetime Symmetry Violation,"Supersymmetric models with Lorentz violation can be formulated in superspace.
Two theories based on the Wess-Zumino model are discussed. A compactification
of superspace can be employed to understand the chiral superfield that arises
in the models.",0412352v1
2005-07-19,K -> pi gamma decays and space-time noncommutativity,"We propose the K -> pi gamma decay mode as a signature of the violation of
the Lorentz invariance and the appearance of new physics via space-time
noncommutativity.",0507231v2
2005-11-22,Vacuum Cherenkov radiation in Maxwell-Chern-Simons electrodynamics,"We study the Cherenkov effect in the context of the Maxwell-Chern-Simons
(MCS) limit of the Standard Model Extension. We present a method to determine
the exact radiation rate for a point charge.",0511265v1
2006-08-18,Meson-Baryon Effective Chiral Lagrangians to O(q^3),"We construct the complete and minimal O(q^2) and O(q^3) three-flavour Lorentz
invariant chiral meson-baryon Lagrangians for the first time in the literature.
We compare with previous three-flavour studies reducing the number of
independent monomials and adding new ones that were missing.",0608204v1
2006-12-29,The Standard-Model Extension and Tests of Relativity,"The Standard-Model Extension, or SME, is a general framework for the study of
Lorentz violation in physics. A broad variety of experiments is able to access
the SME coefficient space. This proceedings briefly summarizes theory and
experiments aimed at testing Special Relativity by measuring these
coefficients.",0612367v1
1992-05-20,The N=2(4) string is self-dual N=4 Yang-Mills,"N=2 string amplitudes, when required to have the Lorentz covariance of the
equivalent N=4 string, describe a self-dual form of N=4 super Yang-Mills in 2+2
dimensions. Spin-independent couplings and the ghost nature of SO(2,2)
spacetime make it a topological-like theory with vanishing loop corrections.",9205075v2
1993-04-28,The Projective Unitary Irreducible Representations of the Poincaré Group in 1+2 Dimensions,"We give a complete analysis of the projective unitary irreducible
representations of the Poincar\'e group in 1+2 dimensions applying Mackey
theorem and using an explicit formula for the universal covering group of the
Lorentz group in 1+2 dimensions. We provide explicit formulae for all
representations.",9304142v1
1993-06-30,Massive Vector Chern-Simons Gravity,"We present a second order gravity action which consists of ordinary Einstein
action augmented by a first-order, vector like, Chern-Simons quasi topological
term.This theory is ghost-free and propagates a pure spin-2 mode. It is
diffeomorphism invariant, although its local Lorentz invariance has been
spontaneously broken.",9307003v1
1993-07-24,$k^+=0$ Modes in Light-Cone Quantization,"We investigate the light-cone quantization of $\phi^3$ theory in 1+1
dimensions with a regularization of discretized light-cone momentum $k^+$.
Solving a second-class constraint associated with the $k^+=0$ mode, we show
that the $k^+=0$ mode propagates along the internal lines of Feynman diagrams
in any order of perturbation, hence our theory recovers the Lorentz invariance.",9307146v1
1993-09-07,Reflection equations and q-Minkowski space algebras,"We express the defining relations of the $q$-deformed Minkowski space algebra
as well as that of the corresponding derivatives and differentials in the form
of reflection equations. This formulation encompasses the covariance properties
with respect the quantum Lorentz group action in a straightforward way.",9309036v1
1993-09-10,Cosmological Solutions in 2D PoincarÉ Gravity,"Abtract: The 2D model of gravity with zweibeins $e^{a}$ and the Lorentz
connection one-form $\omega^{a}_{\ b}$ as independent gravitational variables
is considered. The solutions of classical equations of motion which can be
interpreted as cosmological ones are studied.",9309062v2
1994-01-05,A new constraints separation for the original D=10 massless superparticle,"We study the problem of covariant separation between first and second class
constraints for the $D=10$ Brink-Schwarz superparticle. Opposite to the
supersymmetric light-cone frame separation, we show here that there is a
Lorentz covariant way to identify the second class constraints such that,
however, supersymmetry is broken. Consequences for the $D=10$ superstring are
briefly discussed.",9401011v1
1994-02-09,BPS Dyon in a Weak Electromagnetic Field: Equations of Motion and Radiation Fields,"Dynamics of a BPS dyon in a weak, constant, electromagnetic field is studied
through a perturbative analysis of appropriate non-linear field equations. The
full Lorentz force law for a BPS dyon is established. Also derived are the
radiation fields accompanying the motion.",9402049v1
1994-04-07,Exact Solution of 2D Poincare Gravity Coupled to Fermion Matter,"The 2D model of gravity with zweibeins $e^{a}$ and the Lorentz connection
one-form $\omega^{a}_{\ b}$ as independent gravitational variables coupled to
2d massless Dirac matter is considered. It is shown that the classical
equations of motion are exactly integrated in the case of chiral fermions.",9404045v1
1994-08-01,Unification of Spins and Charges in Grassmann Space?,"In a space of d $(d > 5) $ ordinary and d Grassmann coordinates, fields
manifest in an ordinary four-dimensional subspace as spinor (1/2, 3/2), scalar,
vector or tensor fields with the corresponding charges, according to two kinds
of generators of the Lorentz transformations in the Grassmann space. Vielbeins
and spin connections define gauge fields-gravitational and Yang-Mills.",9408002v1
1994-08-19,Hilbert Space Representation of an Algebra of Observables for q-Deformed Relativistic Quantum Mechanics,"Using a representation of the q-deformed Lorentz algebra as differential
operators on quantum Minkowski space, we define an algebra of observables for a
q-deformed relativistic quantum mechanics with spin zero. We construct a
Hilbert space representation of this algebra in which the square of the mass $
p^2 $ is diagonal.",9408111v1
1994-09-19,Deformed Poincare Algebra and Field Theory,"We examine deformed Poincar\'e algebras containing the exact Lorentz algebra.
We impose constraints which are necessary for defining field theories on these
algebras and we present simple field theoretical examples. Of particular
interest is a case that exhibits improved renormalization properties.",9409106v1
1994-10-04,Why Don't We Have a Covariant Superstring Field Theory?,"This talk deals with the old problem of formulatingn a covariant quantum
theory of superstrings, ``covariant'' here meaning having manifest Lorentz
symmetry and supersymmetry. The advantages and disadvantages of several
quantization methods are reviewed. Special emphasis is put on the approaches
using twistorial variables, and the algebraic structures of these. Some
unsolved problems are identified.",9410014v1
1995-01-04,Strings with interacting ends,"At the classical level we study open bosonic strings. A generic description
of string self-interactions localized at string ends is given.
Self-interactions are characterized by two dimensionless coupling constants.
The model is rewritten using complex Liouville fields. Using these Lorentz and
reparametrization invariant variables, equations of motion get greatly
simplified and reduce to some boundary problem for Liouville equation.",9501009v1
1995-04-28,Extra Dirac Equations,"This paper has rather a pedagogical meaning. Surprising symmetries in the
$(j,0)\oplus (0,j)$ Lorentz group representation space are analyzed. The aim is
to draw reader's attention to the possibility of describing the particle world
on the ground of the Dirac ""doubles"". Several tune points of the variational
principle for this kind of equations are briefly discussed.",9504159v1
1995-06-29,Remarks on chiral symmetry breaking with massless fermions,"In this talk I present recent results on Lorentz covariant correlation
functions $\langle q(p_1)\overline{q}(p_2)\rangle$ on the cone $p^2=0$. In
particular, chiral symmetry breaking terms are constructed which resemble
fermionic 2--point functions of 2--D CFT up to a scalar factor.",9506197v2
1995-09-22,Lorentz-Covariant Analysis of a Quantum Soliton,"A set of integral relations for rotational and translational zero modes in
the vicinity of the classical soliton solution are derived from the
particle-like properties of the latter. The validity of these all relations is
considered for a number of soliton models in 2+1- and 3+1-dimensions.",9509122v1
1995-11-18,Lorentz Anomaly and 1+1-Dimensional Radiating Black Holes,"The radiation from the black holes of a 1+1-dimensional chiral quantum
gravity model is studied. Most notably, a non-trivial dependence on a
renormalization parameter that characterizes the anomaly relations is uncovered
in an improved semiclassical approximation scheme; this dependence is not
present in the naive semiclassical approximation.",9511133v1
1995-12-19,Wigner's Last Papers on Spacetime Symmetries,"Wigner's 1939 paper on representations of the inhomogeneous Lorentz group is
one of the most fundamental papers in physics. Wigner maintained his passion
for this subject throughout his life. In this report, I will review the papers
which he published with me on this subject. These papers deal with the question
of unifying the internal space-time symmetries of massive and massless
particles.",9512151v1
1996-02-05,Two Different Squeeze Transformations,"Lorentz boosts are squeeze transformations. While these transformations are
similar to those in squeezed states of light, they are fundamentally different
from both physical and mathematical points of view. The difference is
illustrated in terms of two coupled harmonic oscillators, and in terms of the
covariant harmonic oscillator formalism.",9602019v1
1996-03-14,The cancellation of worldsheet anomalies in the D=10 Green--Schwarz heterotic string sigma--model,"We determine the two--dimensional Weyl, Lorentz and $\kappa$--anomalies in
the $D=10$ Green--Schwarz heterotic string sigma--model, in an
$SO(1,9)$-Lorentz covariant background gauge, and prove their cancellation.",9603093v1
1996-07-29,About the kinematics of spinning particles,"Inserting the correct Lorentz factor into the definition of the 4-velocity
v^mu for spinning particles entails new kinematical properties for v^2. The
well-known constraint (identically true for scalar particles, but entering also
the Dirac theory, and assumed a priori in all spinning particle models) p_mu
v^mu = m is here derived in a self-consistent way.",9607213v1
1996-09-17,De Dirac a Maxwell: un Camino con Grupo de Lorentz,"This is a brief introduction on the graduate level to recent ideas in the
Weinberg $(j,0)\oplus (0,j)$ formalism, appearing after presentation of the
Bargamann-Wightman-Wigner-type quantum field theory by D. V. Ahluwalia {\it et
al.}",9609149v1
1997-04-09,Absence of Radiation Reaction for an Extended Particle in Classical Electrodynamics,"There are known problems with the standard Lorentz-Dirac description of
radiation reaction in classical electrodynamics. The model of extended in one
dimension particle is proposed and is shown that for this model there is no
total change in particle momentum due to radiation reaction",9704072v2
1997-04-11,Pasti-Sorokin-Tonin Actions in the Presence of Sources,"Pasti, Sorokin and Tonin have recently constructed manifestly
Lorentz-invariant actions for self-dual field strengths and for Maxwell fields
with manifest electromagnetic duality. Using the method of Deser, Gomberoff,
Henneaux and Teitelboim, we generalize these actions in the presence of
sources.",9704093v1
1997-05-08,Covariant Quantization of D-branes,"We have found that kappa-symmetry allows a covariant quantization provided
the ground state of the theory is strictly massive. For D-p-branes a
Hamiltonian analysis is performed to explain the existence of a manifestly
supersymmetric and Lorentz covariant description of the BPS states of the
theory. The covariant quantization of the D-0-brane is presented as an example.",9705056v1
1998-06-16,"N=1, D=10 Tensionless Superbranes I","We consider a model for tensionless (null) super p-branes in the Hamiltonian
approach and in the framework of a harmonic superspace. The obtained algebra of
Lorentz-covariant, irreducible, first class constraints is such that the BRST
charge corresponds to a first rank system.",9806134v1
1998-06-30,Evaporation of Schwarzschild Black Hole in the Large N Matrix Theory,"By using the D0-brane cluster picture, we consider the Hawking radiation of
Schwarszchild black hole (SBH) in large N Matrix model. We get the correct
formula for the the Hawing evaporation rate. Our results give some evidence on
the Lorentz invariance of the physics of Matrix model.",9806245v2
1998-07-02,Couplings between generalized gauge fields,"We analyze the BRST field-antifield construction for generalized gauge fields
consisting of massless mixed representations of the Lorentz Group and we
calculate all the strictly gauge invariant interactions between them. All these
interactions are higher derivative terms constructed out from the derivatives
of the curl of field strength.",9807016v1
1998-07-04,Decoupling of Zero-Modes and Covariance in the Light-Front Formulation of Supersymmetric Theories,"We show under suitable assumptions that zero-modes decouple from the dynamics
of non-zero modes in the light-front formulation of some supersymmetric field
theories. The implications for Lorentz invariance are discussed.",9807035v1
1998-07-28,Superembedding approach and generalized action in String/M-theory,"A brief introduction to superembedding approach (SEA) in its variant based on
the generalized action principle (GAP) for super-p-branes is given. A role of
harmonic variables for Lorentz group is stressed. A relation of the GAP with
complete superfield actions is noted. Recent applications in studying of
Dirichlet branes (super-Dp-branes) and M-branes are discussed.",9807202v1
1998-11-17,Some mathematical considerations about generalized Yang-Mills theories,"Generalized Yang-Mills theories are constructed, that can use fields other
than vector as gauge fields. Their geometric interpretation is studied. An
application to the Glashow-Weinberg-Salam model is briefly review, and some
related mathematical and physical considerations are made.",9811135v1
1999-04-06,Lorentz and CPT Violating Chern-Simons Term in the Formulation of Functional Integral,"We show that in the functional integral formalism the (finite) coefficient of
the induced, Lorentz- and CPT-violating Chern-Simons term, arising from the
Lorentz- and CPT-violating fermion sector, is undetermined.",9904037v1
1999-06-22,Fractional spin and the Pauli term,"It has recently been claimed that the inclusion of a Pauli term in (2+1)
dimensions gives rise to a new type of anomalous spin term. The form of that
term is shown to contradict the structure relations for the inhomogeneous
Lorentz group.",9906172v1
1999-10-04,Covariant formulation of non-Abelian gauge theories without anticommuting variables,"A manifestly Lorentz invariant effective action for Yang-Mills theory
depending only on commuting fields is constructed. This action posesses a
bosonic symmetry, which plays a role analogous to the BRST symmetry in the
standard formalism.",9910029v1
1999-12-21,Irreducible Hamiltonian BRST approach to topologically coupled abelian forms,"An irreducible Hamiltonian BRST approach to topologically coupled p- and
(p+1)-forms is developed. The irreducible setting is enforced by means of
constructing an irreducible Hamiltonian first-class model that is equivalent
from the BRST point of view to the original redundant theory. The irreducible
path integral can be brought to a manifestly Lorentz covariant form.",9912201v1
2000-03-01,A Quantum field theory of dyons,"We construct a classical field theory action which upon quantization via the
functional integral approach, gives rise to a consistent Dirac-string
independent quantum field theory. The approach entails a systematic derivation
of the correlators of all gauge invariant observables, and also of charged
dyonic fields. Manifest SO(2)-duality invariance and Lorentz invariance are
ensured by the PST-approach.",0003003v1
2000-05-22,A component of superconnection of 11-dimensional curved superspace at second order in anticommuting coordinates,"We calculate a component of connection superfields and Lorentz superparameter
at second order in anticommuting coordinates in terms of the component fields
of 11-dimensional on-shell supergravity by using `Gauge completion'. This
configuration of superspace holds the $\kappa $-symmetry for supermembrane
Lagrangian and represents 11-dimensional on-shell supergravity.",0005196v1
2000-08-02,Pulse interaction in nonlinear vacuum electrodynamics,"The energy-momentum conservation law is used to investigate the interaction
of pulses in the framework of nonlinear electrodynamics with Lorentz-invariant
constitutive relations. It is shown that for the pulses of the arbitrary shape
the interaction results in phase shift only.",0008021v1
2000-11-29,Supersymmetric Field Theories on Deformed Space-Time,"Field theories on ""quantum"" or deformed space-time are considered here. The
Moyal-Weyl deformation breaks the Lorentz invariance of the theory, but one can
still require invariance under the supertranslation algebra. We investigate
some aspects of the Wess-Zumino model, super Yang-Mills theories and analyze
the correspondence of the later with the supersymmetric Born-Infeld action.",0011268v1
2001-03-19,Bouncing Branes,"Two classical scalar fields are minimally coupled to gravity in the
Kachru-Shulz-Silverstein scenario with a rolling fifth radius. A Tolman
wormhole solution is found for a R x S^3 brane with Lorentz metric and for a R
x AdS_3 brane with positive definite metric.",0103151v1
2001-06-09,Lorentz invariance and confined noncommutativity,"There have been comments on this paper which point out unclear motivation and
definitions on noncommutative momentum introduced. Therefore, this paper is
withdrawn by the author for more clear presentation.",0106074v3
2001-06-24,Quantum Determinism for Free Vector Bosons in 3 Dimensions,"We apply 't Hooft's deterministic quantum mechanics approach to free vector
bosons in three dimensions and check Lorentz invariance. This approach does not
work for the conformal group, for free bosons in two dimensions. This presents
a technical difficulty for constructing a ``deterministic string theory''.",0106216v1
2001-11-19,On the Canonical Treatment of Lagrangian Constraints,"The canonical treatment of dynamic systems with manifest Lagrangian
constraints proposed by Berezin is applied to concrete examples: a special
Lagrangian linear in velocities, relativistic particles in proper time gauge, a
relativistic string in orthonormal gauge, and the Maxwell field in the Lorentz
gauge,",0111164v1
2002-03-14,Green Function for Spin 1/2 particle in a Coulomb + Scalar Potential,"We calculate the Green function for the Dirac equation describing a spin 1/2
particle in the presence of a potential which is a sum of the Coulomb potential
V_C=-A_1/r and a Lorentz scalar potential V_S=-A_2/r. The bound state spectrum
is obtained.",0203133v1
2002-04-04,S-matrix for spin 1/2 particle in a Coulomb + Scalar potential,"The S-matrix for a spin 1/2 particle in the presence of a potential which is
the sum of the Coulomb potential V_c=-A_1/r and a Lorentz scalar potential V_s=
-A_2/r is calculated",0204044v1
2002-04-19,A Lie-Algebra model for a noncommutative space time geometry,"We propose a Lie-algebra model for noncommutative coordinate and momentum
space . Based on a rigid commutation relation for the commutators of space time
operators the model is quite constrained if one tries to keep Lorentz
invariance as much as possible. We discuss the question of invariants esp. the
definition of a mass.",0204162v2
2002-12-27,"Instantons and SL(2,R) Symmetry in Type IIB Supergravity","We discuss the relation between the dual formulations of Type IIB
supergravity emphasizing the differences between Lorentz and Euclidean
signature. We demonstrate how the SL(2,R) symmetry of the usual action is
manifested in the solution of the equations of motion with Euclidean signature
for the dual theory.",0212322v1
2003-03-19,Bound-state gravity from higher derivatives,"In certain Lorentz-covariant higher-derivative field theories of spins < or
=1, would-be ultraviolet divergences generate color-singlet poles as infrared
divergences. Absence of higher-order poles implies ten-dimensional
supersymmetric Yang-Mills with bound-state supergravity, in close analogy with
open string theory.",0303171v1
2003-05-11,On Concept of Parity for a Fermion,"The known problem of fermion parity is considered on the base of
investigating possible linear single-valued representations of spinor coverings
of the extended Lorentz group. It is shown that in the frame of this theory
does not exist, as separate concepts, P-parity and T-parity for a fermion,
instead only some unified concept of (PT)-parity can be determined in a
group-theoretical language.",0305083v1
2003-06-02,String theory in Lorentz-invariant light cone gauge - III,"This paper completes the work, initiated in [hep-th/9906003,hep-th/0301204],
further referred as Parts I and II, concerning to Dirac's quantization of
Nambu-Goto theory of open string, formulated in the space-time of dimension
d=4. Here we perform more detailed study of Gribov's copies in the classical
mechanics and determine the quantum spectrum of masses for the arbitrary spin
case.",0306010v1
2003-09-12,Vacuum Electrodynamics of Accelerated Systems: Nonlocal Maxwell's Equations,"The nonlocal electrodynamics of accelerated systems is discussed in
connection with the development of Lorentz-invariant nonlocal field equations.
Nonlocal Maxwell's equations are presented explicitly for certain linearly
accelerated systems. In general, the field equations remain nonlocal even after
accelerated motion has ceased.",0309124v1
2003-10-01,Lorentz and Galilei Invariance on Lattices,"We show that the algebraic aspects of Lie symmetries and generalized
symmetries in nonrelativistic and relativistic quantum mechanics can be
preserved in linear lattice theories. The mathematical tool for symmetry
preserving discretizations on regular lattices is the umbral calculus.",0310013v1
2004-03-23,Trans-Planckian corrections to the primordial spectrum in the infra-red and the ultra-violet,"Due to the tremendous red-shift that occurs during the inflationary epoch in
the early universe, it has been realized that trans-Planckian physics may
manifest itself at energies much lower than the Planck energy. The presence of
a fundamental scale suggests that local Lorentz invariance may be violated at
sufficiently high energies. Motivated by this possibility, recently, different
models that violate Lorentz invariance locally have been used to evaluate the
trans-Planckian corrections to the inflationary density perturbation spectrum.
However, certain astrophysical observations seem to indicate that local Lorentz
invariance may be preserved to extremely high energies. In such a situation, to
study the trans-Planckian effects, it becomes imperative to consider models
that preserve local Lorentz invariance even as they contain a fundamental
scale. In this work, we construct one such model and evaluate the resulting
spectrum of density perturbations in the power-law inflationary scenario. While
our model reproduces the standard spectrum on small scales, it naturally
predicts a suppression of power on large scales. In fact, the spectrum we
obtain has some features which are similar to the one that has recently been
obtained from non-commutative inflation. However, we find that the amount of
suppression predicted by our model is far less than that is required to fit the
observations. We comment on the fact that, with a suitable choice of initial
conditions, our approach can lead to corrections at the infra-red as well as at
the ultra-violet ends of the spectrum.",0403236v3
2004-08-12,Lorentz-Invariant Interpretation of Noncommutative Space-Time - global version,"The global version of the quantum symmetry defined by Chaichian et al
(hep-th/0408069) is constructed.",0408100v3
2004-11-23,Why three generations?,"A brief review is given of particle physics, gauge fields and gravity, based
on a scheme whereby five complex (Lorentz scalar) anticommuting coordinates are
appended to four dimensional space-time; the resulting model is effectively
zero-dimensional.",0411219v1
2005-07-21,Confinement of spinless particles by Coulomb potentials in two-dimensional space-time,"The problem of confinement of spinless particles in 1+1 dimensions is
approached with a linear potential by considering a mixing of Lorentz vector
and scalar couplings. Analytical bound-states solutions are obtained when the
scalar coupling is of sufficient intensity compared to the vector coupling.",0507218v1
2005-11-08,An Interpretation of Noncommutative Field Theory in Terms of a Quantum Shift,"Noncommutative coordinates are decomposed into a sum of geometrical ones and
a universal quantum shift operator. With the help of this operator, the mapping
of a commutative field theory into a noncommutative field theory (NCFT) is
introduced. A general measure for the Lorentz-invariance violation in NCFT is
also derived.",0511094v1
2005-12-29,On the supersymmetric completion of the $R^4$ term in M-theory,"We examine the question of finding the supersymmetric completion of the $R^4$
term in M-theory. Using superfield methods, we present an eight derivative
action in eight dimensions that has 32 preserved supersymmetries. We show also
that this action has a hidden eleven-dimensional Lorentz invariance. It can
thus be uplifted to give the complete set of bosonic terms in the M-theory
eight derivative action.",0512333v1
2006-02-06,Non-Abelian Gauged Chiral Boson with a Generalized Faddevian Regularization,"We consider non-Abelian gauged version of chiral boson with a generalized
Faddeevian regularization. It is a second class constrained theory. We quantize
the theory and analyze the phase space. It is shown that in spite of the lack
of manifest Lorentz invariance in the action, it has a consistent and Poincare'
invariant phase space structure.",0602052v2
2006-03-16,Theta-twisted Gravity,"We describe a theory of gravitation on canonical noncommutative spacetimes.
The construction is based on theta-twisted General Coordinate Transformations
and Local Lorentz Invariance.",0603132v2
2006-03-30,Three particle Pomeron and odderon states in QCD,"The scattering amplitude of hadrons in high energy Regge limit can be
rewritten in terms of reggeized gluons, i.e. Reggeons. We consider
three-Reggeon states that possess either C=+1 or C=-1 parity. In this work
using Janik-Wosiek method the spectrum of conformal charges is calculated for
states with conformal Lorentz spin n_h=0,1,2,3,... . Moreover corrections to
WKB approximation are computed.",0603238v1
2006-09-28,Wightman-Function Approach to the Relativistic Complex-Ghost Field Theory,"The relativistic complex-ghost field theory is covariantly formulated in
terms of Wightman functions. The Fourier transform of the 2-point Wightman
function of a complex-ghost pair is explicitly calculated, and its spontaneous
breakdown of Lorentz invariance is compared with that of the corresponding
Feynman integral.",0609206v1
2006-10-27,A Positive-Definite Scalar Product for Free Proca Particle,"We implement recent results of pseudo-Hermitian quantum mechanics to
description of relativistic massive particle with spin-one. We derive a
one-parameter family of Lorentz invariant positive-definite scalar products on
the space of solutions of Proca equation.",0610290v1
2006-11-29,Nonlocal Dirac Equation for Accelerated Observers,"The nonlocal theory of accelerated systems is extended to the propagation of
Dirac particles. The implications of nonlocality for the phenomenon of
spin-rotation coupling are discussed. The Lorentz-invariant nonlocal Dirac
equation is presented for certain special classes of accelerated observers.",0611319v2
2007-02-14,Nonspontaneous Supersymmetry Breaking,"A new way of supersymmetry breaking involving a dynamical parameter is
introduced. It is independent of particle phenomenology and gauge groups. The
only requirement is that Lorentz invariance be valid strictly infinitesimally
(i. e. Spin(1,3) be for some values of the parameter replaced by a compact
group G locally isomorphic to Spin(1,3).",0702116v1
1998-01-22,q-Deformed Minkowski Space based on a q-Lorentz Algebra,"The Hilbert space representations of a non-commutative q-deformed Minkowski
space, its momenta and its Lorentz boosts are constructed. The spectrum of the
diagonalizable space elements shows a lattice-like structure with accumulation
points on the light-cone.",9801104v1
1998-06-24,The Virasoro group and the fourth geometry of Poincaré,"We investigate, in some details, symplectic equivalence between several
conformal classes of Lorentz metrics on the hyperboloid of one sheet $H^{1,1}
\cong T \times T - \Delta$ and affine coadjoint orbits of the group
$Diff_+(\Delta)$ of orientation preserving diffeomorphisms of $\Delta \cong T$
with its natural projective structure. This will allow for generalizations,
namely, to the case of arbitrary projective structures on null infinity.",9806135v1
1998-12-29,Tensor product in symmetric function spaces,"A concept of multiplicator of symmetric function space concerning to
projective tensor product is introduced and studied. This allows to obtain some
concrete results. In particular, the well-known theorem of R. O'Neil about the
boundedness of tensor product in the Lorentz spaces L_{p,q} is discussed.",9812155v1
2001-12-01,The coarea formula for Sobolev mappings,"We extend Federer's coarea formula to mappings $f$ belonging to the Sobolev
class $W^{1,p}(R^n;R^m)$, $1 \le m < n$, $p>m$, and more generally, to mappings
with gradient in the Lorentz space $L^{m,1}(R^n)$. This is accomplished by
showing that the graph of $f$ in $R^{n+m}$ is a Hausdorff $n$-rectifiable set.",0112008v1
2002-06-27,Aperiodic Lorentz gas: recurrence and ergodicity,"We prove that any generic (i.e., possibly aperiodic) Lorenz gas in two
dimensions, with finite horizon and non-degenerate geometrical features, is
ergodic if it is recurrent. We also give examples of aperiodic recurrent gases.",0206299v1
2003-04-29,Local well-posedness for the Maxwell-Schrödinger equation,"Time local well-posedness for the Maxwell-Schr\""odinger equation in the
coulomb gauge is studied in Sobolev spaces by the contraction mapping
principle. The Lorentz gauge and the temporal gauge cases are also treated by
the gauge transform.",0304486v2
2003-12-03,A bifurcation result for semi-Riemannian trajectories of the Lorentz force equation,"By decision of the first author, the paper will no longer be available.",0312090v3
2004-10-20,Relative parabolicity of zero mean curvature surfaces in $R^3$ and $R_1^3$,"If the Lorentzian norm on a maximal surface in the 3-dimensional
Lorentz-Minkowski space $R_1^3$ is positive and proper, then the surface is
relative parabolic. As a consequence, entire maximal graphs with a closed set
of isolated singularities are relative parabolic.
  Furthermore, maximal and minimal graphs over closed starlike domains in
$R_1^3$ and $R^3,$ respectively, are relative parabolic.",0410435v1
2005-02-23,On the theory of 1-motives,"This is an overview and a preview of the theory of ""mixed motives of level 1""
explaining some results, projects, ideas and indicating a bunch of problems.",0502476v3
2005-03-18,Invariant triple products,"It is shown that the space of invariant trilinear forms on smooth
representations of a semisimple Lie group is finite dimensional if the group is
a product of Lorentz groups.",0503379v5
2006-02-20,Optimal domain for the Hardy operator,"We study the optimal domain for the Hardy operator considered with values in
a rearrangement invariant space. In particular, this domain can be represented
as the space of integrable functions with respect to a vector measure defined
on a $\delta$-ring. A precise description is given for the case of the minimal
Lorentz spaces.",0602426v1
2006-12-10,A functional limit theorem for the position of a particle in a Lorentz type model,"Consider a particle moving through a random medium, which consists of
spherical obstacles, randomly distributed in R^d. The particle is accelerated
by a constant external field; when colliding with an obstacle, the particle
inelastically reflects. We study the asymptotics of X(t), which denotes the
position of the particle at time t, as t tends to infinity. The result is a
functional limit theorem for X(t).",0612253v1
2003-09-04,Splitting the Kemmer-Duffin-Petiau Equations,"We study internal structure of the Kemmer-Duffin-Petiau equations for spin-0
and spin-1 mesons. We demonstrate, that the Kemmer-Duffin-Petiau equations can
be splitted into constituent equations, describing particles with definite mass
and broken Lorentz symmetry. We also show that solutions of the three component
constituent equations fulfill the Dirac equation.",0309013v1
2003-09-30,Imaginary in all directions: an elegant formulation of special relativity and classical electrodynamics,"A suitable parameterization of space-time in terms of one complex and three
quaternionic imaginary units allows Lorentz transformations to be implemented
as multiplication by complex-quaternionic numbers rather than matrices.
Maxwell's equations reduce to a single equation.",0309061v1
2004-10-22,Discrete model of Yang-Mills equations in Minkowski space,"Using methods of differential geometry, a discrete analog of the Yang-Mills
equations in Minkowski space is constructed. The gauge transformation law in a
discrete formulation is given and gauge invariance of discrete Yang-Mills
equations is studied. Difference self-dual and anti-self-dual equations with
respect to the Lorentz metric are presented.",0410047v1
2003-02-06,Anomalous transport: a deterministic approach,"We introduce a cycle-expansion (fully deterministic) technique to compute the
asymptotic behavior of arbitrary order transport moments. The theory is applied
to different kinds of one-dimensional intermittent maps, and Lorentz gas with
infinite horizon, confirming the typical appearance of phase transitions in the
transport spectrum.",0302013v2
2003-10-17,Periodic orbit theory of strongly anomalous transport,"We establish a deterministic technique to investigate transport moments of
arbitrary order. The theory is applied to the analysis of different kinds of
intermittent one-dimensional maps and the Lorentz gas with infinite horizon:
the typical appearance of phase transitions in the spectrum of transport
exponents is explained.",0310025v2
1997-10-28,"The Rarita-Schwinger spin-3/2 equation in a nonuniform, central potential","The equations of motion for a massive spin-3/2 Rarita-Schwinger field in a
finite-range, central, Lorentz scalar potential are developed. It is shown that
the resulting density may not be everywhere positive definite.",9710066v1
2002-11-04,Gauge and Lorentz invariant pionic correlations in quasi-elastic electron scattering,"The role of the pion in the parity-conserving and parity-violating
quasi-elastic nuclear response functions is analyzed within a relativistic
model which fulfills gauge invariance.",0211006v2
2003-03-26,Bound state kinetics in high-energy nuclear collisions,"A Lorentz covariant kinetic equation for bound states and their constituents
is presented and solved exactly in closed form. It describes in a unified way
dynamical formation and dissociation of states such as quarkonia and
(anti)-deuterons in the excited medium formed with a high-energy heavy-ion
collision.",0303065v1
2004-07-29,"Pseudospin, Spin, and Coulomb Dirac-Symmetries: Doublet Structure and Supersymmetric Patterns","Relativistic symmetries of the Dirac Hamiltonian with a mixture of
spherically symmetric Lorentz scalar and vector potentials, are examined from
the point of view of supersymmetric quantum mechanics. The cases considered
include the Coulomb, pseudospin and spin limits relevant, respectively, to
atoms, nuclei and hadrons.",0407107v1
1997-12-02,Lorentz Symmetry Violation and High-Energy Cosmic Rays,"We discuss possible violations of Poincare's relativity principle at energy
scales close to Planck scale and point out the potentialities of high-energy
cosmic-ray physics to uncover these new phenomena.",9712005v1
1999-10-26,Interaction of the Past of parallel universes,"We constructed a model of five-dimensional Lorentz manifold with foliation of
codimension 1 the leaves of which are four-dimensional space-times. The Past of
these space-times can interact in macroscopic scale by means of large quantum
fluctuations. Hence, it is possible that our Human History consists of
""somebody else's"" (alien) events.",9910037v1
2000-05-25,The Theory of Fractal Time: Field Equations (the Theory of Almost Inertial Systems and Modified Lorentz Transformations),"Field equations in four order derivatives with respect to time and space
coordinates based on modified classic relativistic energy of the fractal theory
of time and space are received. It is shown appearing of new spin
characteristics and new fields with imaginary energies .",0005068v1
2000-08-28,The easiest way to Heaviside ellipsoid,"The formula for the electric field of a point charge moving with constant
velocity is derived using the symmetry properties of Maxwell's equations - its
Lorentz invariance. In contrast to conventional treatments, the derivation
presented does not use retarded integrals or relativity transformations.",0008225v2
2000-10-14,"Comment on ``Do Zero-energy Solutions of Maxwell Equations Have the Physical Origin Suggested by A. E. Chubykalo?"" by V.V. Dvoeglazov","This is the answer to objections put forth in Proceedings of the Zacatecas
Workshop ""Lorentz Group, CPT and Neutrinos"" (World Scientific, Singapore,
2000), pp. 335-341.",0010035v1
2001-01-16,Apparent Lack of Symmetry in Stellar Aberration and Euclidean Space Time,"The effect of stellar aberration seems to be one of the simplest phenomena in
astronomical observations. But there is a large literature about it betraying a
problem of asymmetry between observer motion and source motion. This paper
addresses the problem from the point of view of Euclidean space-time, arising
from the proposition that stellar aberration (or Bradley aberration) gives rise
to a Lorentz expansion.",0101066v1
2001-04-02,Unified Theory of Field with Modul of Squared Curvature as Lagrangian,"The 4-D theory with connection components Gamma^k_{mn} as field variables and
module of squared curvature |R^k_{lmn}R^{lmn}_k| as Lagrangian is described.
The Maxwell equations, the Lorentz condition and the gravity field equation,
that agrees with Newton's theory, result from equations of motion.",0104008v2
2002-08-10,Restriction Conditions of Motion Equations of Non-Abelian Gauge Fields and Their Wave Solutions,"Similar to introduce the Lorentz condition in the motion equation of
electromagnetic field, the restriction condition is introduced in the motion
equations of non-Ablian gauge fields so that the equations are simplified
greatly and their wave solutions are obtained. Only in this way, the Feynman
rule's use become rightful in the calculation of perturbation theory.",0208042v1
2003-03-20,A singular integrable equation from short capillary-gravity waves,"From a columnar approximation of the Euler equations of an incompressible
fluid with surface tension, we derive in the short-wave approximation a new
integrable classical 1+1 dimensional field theory for the motion of the
surface. Together with a Lorentz invariance,this system has the novel feature
of solutions which become multiple valued in finite time.",0303085v1
2003-10-02,The Thomas Precession Factor in Spin-Orbit Interaction,"The origin of the Thomas factor 1/2 in the spin-orbit hamiltonian can be
understood by considering the case of a classical electron moving in crossed
electric and magnetic fields chosen such that the electric Coulomb force is
balanced by the magnetic Lorentz force.",0310016v1
2003-12-10,Negative optical refractive index resulting from a moving regular medium,"The optical refractive index of a moving regular medium is calculated by
using the Lorentz transformation in this note. It is shown that in some
velocity region of medium moving relative to the initial frame K, the moving
medium may possess a negative index of refraction measured by the observer
fixed at the frame of reference K.",0312064v1
2003-12-18,Noncommutative Geometry and Some Issues,"Recent observations of Ultra High Energy Cosmic rays suggest a small
violation of Lorentz symmetry. Such a violation is expected in schemes with
discrete/quantized spacetime. We examine this situation and suggest tests which
could be carried out, for example by NASA's GLAST Satellite. The considerations
are extrapolated to the large scale cosmos.",0312109v1
2004-02-12,The Thermal Radiation Formula of Planck (1900),"We review the derivation of Planck's Radiation Formula on the light of recent
studies in its centenary. We discuss specially the issue of discreteness,
Planck's opinion on his discovery, and the critical analysis on the
contributions by Ehrenfest, Einstein, Lorentz, etc. We also address the views
of T.S. Kuhn, which conflict with the conventional interpretation that
discontinuty was already found by Planck.",0402064v1
2004-05-05,The Brillouin Instability of intense laser in relativistic plasmas,"This paper studies the propagation of intense laser in plasmas in weak
relativistic region($0.1<a_0^2<0.5$) using the quasi-periodic approximation.
Effective Lorentz factor and density wave effects are calculated in detail. The
relativistic correction on stimulated Brillouin instability is investigated in
the rest parts. The coupled dispersion relations of Stimulated Brillouin
Scattering(SBS) are obtained and investigated numerically.",0405018v1
2004-08-05,Larmor radius effects on impurity transport in turbulent plasmas,"Test particle transport determined by the Lorentz force in turbulent
magnetized plasmas is studied. The time dependent diffusion coefficient, valid
for the whole range of parameters, is obtained by developing the decorrelation
trajectory method. The effects of Larmor gyration in the presence of trapping
are analyzed and several transport regimes are evidenced.",0408029v1
2004-10-21,Minimal Gravitomagnetism,"We show that Feynman's proof applies to Newtonian gravitation, implying thus
the existence of gravitational analogous of the electric and magnetic fields
and the corresponding Lorentz-like force. Consistency of the formalism require
particular properties of the electric and magnetic-like fields under Galilei
transformations, which coincide with those obtained in previous analysis of
Galilean electromagnetism.",0410198v2
2004-11-25,On Onsager Relations and Linear Electromagnetic Materials,"We investigated the Onsager relations in the context of electromagnetic
constitutive relations of linear, homogeneous materials. We determined that
application of the Onsager relations to the constitutive equations relating
$#P$ and $#M$ to both $#E$ and $#B$ is in accord with Lorentz reciprocity as
well as the Post constraint.",0411231v1
2005-02-17,From one space dimension to two space dimensions in special relativity,"Authors derive the Lorentz-Einstein transformation for the space-time
coordinates starting with a one-space dimension approach. They add to the
results the invariance of the space coordinates measured perpendicular to the
direction of relative motion. Students often ask if the transition does not
affect the transformation equation for the time coordinate. Our paper shows
that the transformation of the time coordinate depends only on the x space
coordinate.",0502095v1
2006-09-18,The Physical Meaning of Gauge Transformations in Classical Electrodynamics,"The structure of electrodynamics based on the variational principle together
with causality and space-time homogeneity is analyzed. It is proved that in
this case the 4-potential is defined uniquely. Therefore, the approach where
Maxwell equations and the Lorentz law of force are regarded as cornerstones of
the theory is not equivalent to the one described above.",0609152v1
2006-10-26,On the rational relationship between Heisenberg principle and general relativity,"The research shows that the Heisenberg principle is the logic results of
general relativity principle. If inertia coordinator system is used, the
general relativity will logically be derived from the Heisenberg principle. The
intrinsic relation between the quantum mechanics and general relativity is
broken by introducing pure-imaginary time to explain the Lorentz
transformation. Therefore, this research shows a way to establish an unified
field theory of physics",0610237v1
2006-11-10,"Derivation of magnetic Coulomb's law for thin, semi-infinite solenoids","It is shown that the magnetic force between thin, semi-infinite solenoids
obeys a Coulomb-type law, which corresponds to that for magnetic monopoles
placed at the end points of each solenoid. We derive the magnetic Coulomb law
from the basic principles of electromagnetism, namely from the Maxwell
equations and the Lorentz force.",0611099v1
2006-11-22,The new sight on the Hertz electrodynamics of a moving bodies,"A little error was eliminated from Hertz equations. New Hertz equations do
not contradict to all electromagnetic experiments. Therefore Hertz
electrodynamics is the alternative to Einstein electrodynamics. It means that
the question about the absolute or relative character of both space and time
must be rediscussed. Lorentz transformations can be used only if our
theoretical model of an electromagnetic phenomenon is not complete one .",0611203v2
2006-11-23,Fundamental Properties of Lagrangian Density for A Gravitational System and Their Derivations,"Through the discussion of the fundamental properties of Lagrangian density
for a gravitational system, the theoretical foundations of the modified
Einstein field equations and the Lorentz and Levi-Civita conservation laws are
systematically studied. Our study confirms the view that they could be used as
the premises to establish a new cosmology.",0611221v1
2007-02-14,"Comment on ""Preacceleration without radiation: The nonexistence of preradiation phenomenon,"" by J.A. Heras [Am. J. Phys. 74, 1025 (2006)]","It is argued that a recent claim that there is no radiation in the
preacceleration part of a non-runaway solution of the Abraham--Lorentz equation
is incorrect.",0702121v1
1995-10-20,Quasitriangularity and enveloping algebras for inhomogeneous quantum groups,"Coquasitriangular universal ${\cal R}$ matrices on quantum Lorentz and
quantum Poincar\'e groups are classified. The results extend (under certain
assumptions) to inhomogeneous quantum groups of [10]. Enveloping algebras on
those objects are described.",9510018v2
1996-03-28,Skew Symmetric Bundle Maps on Space-Time,"We study the ""Lie Algebra"" of the group of Gauge Transformations of
Space-time. We obtain topological invariants arising from this Lie Algebra. Our
methods give us fresh mathematical points of view on Lorentz Transformations,
orientation conventions, the Doppler shift, Pauli matrices , Electro-Magnetic
Duality Rotation, Poynting vectors, and the Energy Momentum Tensor $T$ .",9603024v1
1998-06-10,Relativistic properties of marginal distributions,"We study the properties of marginal distributions-projections of the phase
space representation of a physical system-under relativistic transforms. We
consider the Galileo case as well as the Lorentz transforms exploiting the
relativistic oscillator model used for describing the mass spectrum of
elementary particles.",9806035v1
1999-06-29,Quantum superluminal communication does not result in the causal loop,"We show that the quantum superluminal communication based on the quantum
nonlocal influence, if exists, will not result in the causal loop, this
conclusion is essentially determined by the peculiarity of the quantum nonlocal
influence itself, according to which there must exist a preferred Lorentz frame
for consistently describing the quantum nonlocal process.",9906113v2
2001-04-25,n+1 dimensional Dirac equation and the Klein paradox,"The purpose of this comment is to clarify two points related to the Dirac
equation. First, the Lorentz structure of the potential and its connection with
the Klein paradox. Second, the connection between the number of space
dimensions and the number of spinor components.",0104124v1
2001-11-01,Solution of the one-dimensional Dirac equation with a linear scalar potential,"We solve the Dirac equation in one space dimension for the case of a linear,
Lorentz-scalar potential. This extends earlier work of Bhalerao and Ram [Am. J.
Phys. 69 (7), 817-818 (2001)] by eliminating unnecessary constraints. The
spectrum is shown to match smoothly to the nonrelativistic spectrum in a
weak-coupling limit.",0111011v1
2001-11-22,EPR Type Nonlocality in Classical Electrodynamics!,"It is shown that classical electrodynamics in its alternative
Kemmer-Duffin-Petiau-Harish-Chandra formulation surprisingly reveals a Hilbert
space structure leading to the possibility of entangled states of classical
radiation, and this in turn implies the violation of Einstein-Bell locality in
spite of Lorentz invariance.",0111119v1
2001-12-23,Comments on the experimental disproof of Multisimultaneity,"The recent Geneva experiment strikingly displays lawlike reversibility
together with quantum nonseparability. As in any probabilistic physics
correlation expresses interaction, and as Born's probability rules grafted upon
de Broglie's wave mechanics turn the probability scheme into the code of an
information transmitting telegraph, the Lorentz and CPT invariant transition
amplitude reversibly carries a zigzagging causation.",0112150v1
2002-01-28,"Comment on ""Fun and frustration with quarkonium in a 1+1 dimension,"" by R. S. Bhalerao and B. Ram [Am. J. Phys. 69 (7), 817-818 (2001)]","We present the correct solution of the Dirac equation in 1+1 dimensions with
the Lorentz scalar potential V(x)=g|x|.",0201125v1
2002-03-07,Quantum entropy and special relativity,"We consider a single free spin 1/2 particle. The reduced density matrix for
its spin is not covariant under Lorentz transformations. The spin entropy is
not a relativistic scalar and has no invariant meaning.",0203033v2
2002-07-25,Relativistic Spontaneous Localization: A Proposal,"A new proposal for a Lorentz-invariant spontaneous localization theory is
presented. It is based on the choice of a suitable set of macroscopic
quantities to be stochastically induced to have definite values. Such
macroscopic quantities have the meaning of a time-integrated amount of a
microscopically defined quantity called stuff related to the presence of
massive particles.",0207145v1
2002-09-20,Modal Interpretations and Relativity,"A proof is given, at a greater level of generality than previous 'no-go'
theorems, of the impossibility of formulating a modal interpretation that
exhibits 'serious' Lorentz invariance at the fundamental level. Particular
attention is given to modal interpretations of the type proposed by Bub.",0209109v1
2002-10-03,Space-time transformation for superluminal signaling,"We analyze the possible implication of the existence of superluminal
signaling for space-time structure. A new space-time transformation for
superluminal signaling is presented based on the superluminal synchrony method.
We argue that Lorentz transformation should be replaced by the new
transformation in case of the existence of superluminal signaling. Furthermore,
we discuss the possible existence of absolute frame, and give a possible
practical method to probe it.",0210021v1
2003-04-28,A relativistic variant of the Wigner function,"The conventional Wigner function is inappropriate in a quantum field theory
setting because, as a quasiprobability density over phase space, it is not
manifestly Lorentz covariant. A manifestly relativistic variant is constructed
as a quasiprobability density over trajectories instead of over phase space.",0304171v3
2003-10-23,Depurification by Lorentz boosts,"We consider a particle of half-integer spin which is nonrelativistic in the
rest frame. Assuming the particle is completely polarized along third axis we
calculate the Bloch vector as seen by a moving observer. The result for its
length is expressed in terms of dispersion of some vector operator linear in
momentum. The relation with the localization properties is discussed.",0310145v1
2003-11-05,The Equation of Motion of an Electron,"The claim by Rohrlich that the Abraham-Lorentz-Dirac equation is not the
correct equation for a classical point charge is shown to be incorrect and it
is pointed out that the equation which he proposes is the equation
{\underline{derived}} by Ford and O'Connell for a charge with structure. The
quantum-mechanical case is also discussed.",0311021v1
2006-10-06,Metric perturbation theory of quantum dynamics,"A theory of quantum dynamics based on a discrete structure underlying the
space time manifold is developed for single particles. It is shown that at the
micro domain the interaction of particles with the underlying discrete
structure results in the quantum space time manifold. Regarding the resulting
quantum space-time as perturbation from the Lorentz metric it is shown it is
possible to discuss the dynamics of particles in the quantum domain.",0610042v1
2006-12-15,Einstein-Podolsky-Rosen correlations of Dirac particles - quantum field theory approach,"We calculate correlation function in the Einstein--Podolsky--Rosen type of
experiment with massive relativistic Dirac particles in the framework of the
quantum field theory formalism. We perform our calculations for states which
are physically interesting and transforms covariantly under the full Lorentz
group action, i.e. for pseudoscalar and vector state.",0612131v1
2007-04-13,Doubly Special Relativity and Finsler geometry,"We discuss the recent proposal of implementing Doubly Special Relativity in
configuration space by means of Finsler geometry. Although this formalism leads
to a consistent description of the dynamics of a particle, it does not seem to
give a complete description of the physics. In particular, the Finsler line
element is not invariant under the deformed Lorentz transformations of Doubly
Special Relativity. We study in detail some simple applications of the
formalism.",0704.1728v1
2007-05-07,The Measurement of Time,"We present a definition of time measurement based on high energy photons and
the fundamental length scale, and show that, for macroscopic time, it is in
accord with the Lorentz transformation of special relativity. To do this we
define observer in a different way than in special relativity.",0705.1000v1
2007-05-19,Log-periodic drift oscillations in self-similar billiards,"We study a particle moving at unit speed in a self-similar Lorentz billiard
channel; the latter consists of an infinite sequence of cells which are
identical in shape but growing exponentially in size, from left to right. We
present numerical computation of the drift term in this system and establish
the logarithmic periodicity of the corrections to the average drift.",0705.2790v1
2007-05-24,Unparticles and Muon Decay,"Recently Georgi has discussed the possible existence of `Unparticles'
describable by operators having non-integral scaling dimensions. With the
interaction of these with the Standard Model (SM) particles being constrained
only by gauge and Lorentz symmetries, it affords a new source for lepton
flavour violation. Current and future muon decay experiments are shown to be
very sensitive to such scenarios.",0705.3637v1
2007-05-29,Alice and Bob and Hendrik,"This paper offers an alternative approach to discussing both the principle of
relativity and the derivation of the Lorentz transformations. This approach
uses the idea that there may not be a preferred inertial frame through a
privileged access to information about events. In classroom discussions, it has
been my experience that this approach produces some lively arguments.",0705.4255v2
2007-06-04,On the Vacuum Propagation of Gravitational Waves,"We show that, for any local, causal quantum field theory which couples
covariantly to gravity, and which admits Minkowski spacetime vacuum(a)
invariant under the inhomogeneous proper orthochronous Lorentz group, plane
gravitational waves propagating in such Minkowski vacuum(a) do not dissipate
energy or momentum via quantum field theoretic effects.",0706.0231v2
2007-06-13,Recent developments in small-x physics,"Recent theoretical progress in understanding high-energy scattering beyond
the mean field approximation is reviewed. The role of Lorentz invariance and
pomeron loops in the evolution, the relation between high-energy QCD and
statistical physics and results for the saturation momentum and the scattering
amplitude are discussed.",0706.1866v1
2007-06-22,On the Photon Mass,"We review the case for the photon having a tiny mass compatible with the
experimental limits. We go over some possible experimental tests for such a
photon mass including the violation of Lorentz symmetry. We point out that such
violations may already have been witnessed in tests involving high energy gamma
rays from outer space as also ultra high energy cosmic rays.",0706.3319v1
2007-06-25,alpha'-Corrections to Heterotic Superstring Effective Action Revisited,"In this letter we establish that the supersymmetric R^2 effective action for
the heterotic string, obtained from the supersymmetrisation of the Lorentz
Chern-Simons term, is to order $\alpha'$ equivalent modulo field redefinitions
to heterotic string effective actions computed by different methods.",0706.3636v1
2007-07-09,On the Calabi-Yau problem for maximal surfaces in L^3,"In this paper we construct an example of a weakly complete maximal surface in
the Lorentz-Minkowski space L^3, which is bounded by a hyperboloid. Moreover,
all the singularities of our example are of lightlike type.",0707.1098v2
2007-07-17,Invariance of the relativistic one-particle distribution function,"The one-particle distribution function is of importance both in
non-relativistic and relativistic statistical physics. In the relativistic
framework, Lorentz invariance is possibly its most fundamental property. The
present article on the subject is a contrastive one: we review, discuss
critically, and, when necessary, complete, the treatments found in the standard
literature.",0707.2499v1
2007-08-18,Chkareuli-Froggatt-Nielsen Theorem and Photon Mass,"We analyze there is a relation between fossil charge and the mass of photon
based on Chkareuli-Froggatt-Nielsen Theorem and Proca Lagrangian. As generally
known, massive photon will lead to Lorentz non-invariance field theory.",0708.2458v3
2007-09-05,Rearrangement transformations on general measure spaces,"For a general set transformation ${\cal R}$ between two measure spaces, we
define the rearrangement of a measurable function by means of the Layer's cake
formula. We study some functional properties of the Lorentz spaces defined in
terms of ${\cal R}$, giving a unified approach to the classical rearrangement,
Steiner's symmetrization, the multidimensional case, and the discrete setting
of trees.",0709.0648v1
2007-09-11,Analytic Extension of a maximal surface in $\Bbb L^3$ along its boudary,"We prove that a maximal surface in Lorentz-Minkowski space $\Bbb L^3$ can be
extended analytically along its boundary if the boundary lies in a plane
meeting the surface at a constant angle.",0709.1577v1
2007-10-02,Theoretical topics in spacetime-symmetry violations,"The Lorentz- and CPT-violating Chern-Simons extension of electrodynamics is
considered. In the context of N=4 supergravity in four spacetime dimensions, it
is argued that cosmological solutions can generate this extension. Within
Chern-Simons electrodynamics, theoretical and phenomenological topics are
reviewed that concern the number of the remaining spacetime symmetries and the
vacuum Cherenkov effect, respectively.",0710.0411v1
2007-10-02,Elements of Group Theory,"\noindent 1. Generalities\hfil\break 2. Lie groups and Lie
algebras\hfil\break
  3. The unitary groups\hfil\break
  4. Representations of the SU(n) groups (and of their algebras)\hfil\break
  5. The tensor method for unitary groups, and\hb the permutation
group\hfil\break
  6. Relativistic invariance. The Lorentz group\hfil\break
  7. General representation of relativistic states",0710.0468v1
2007-10-09,Dissipative Strong-Field Electrodynamics,"A dissipative Lorentz-covariant Ohm's law which uses only the electromagnetic
degrees of freedom is proposed. For large conductivity, Maxwell equations
equipped with this Ohm's law reduce to the equations of Force-Free
Electrodynamics (FFE) with small dissipative corrections, but only in the
regions where the ideal FFE 4-current is space-like. This might indicate that
the pulsar emission comes primarily from the magnetic separartrix.",0710.1875v1
2007-11-17,Gauge-Invariant Quantities Characterizing Gauge Fields in Chromodynamics,"We calculate Lorentz-invariant and gauge-invariant quantities characterizing
the product $\sum_a D_R(T^a) F^a_{\mu\nu}$, where $D_R(T^a)$ denotes the matrix
for the generator $T^a$ in the representation $R=$ fundamental and adjoint, for
color SU(3). We also present analogous results for an SU(2) gauge theory.",0711.2759v1
2007-11-20,Fourvector algebra,"The algebra of fourvectors is described. The fourvectors are more appropriate
than the Hamilton quaternions for its use in Physics and the sciences in
general. The fourvectors embrace the 3D vectors in a natural form. It is shown
the excellent ability to perform rotations with the use of fourvectors, as well
as their use in relativity for producing Lorentz boosts, which are understood
as simple rotations.",0711.3220v1
2007-11-24,Einstein-aether gravity: theory and observational constraints,"Einstein-aether theory is general relativity coupled to a dynamical unit
timelike vector field. A brief review of current theoretical understanding and
observational constraints on the four coupling parameters of the theory is
given.",0711.3822v1
2008-01-11,Exact solution of the Landau-Lifshitz equation in a plane wave,"The Landau-Lifshitz form of the Lorentz-Abraham-Dirac equation in the
presence of a plane wave of arbitrary shape and polarization is solved exactly
and in closed form. The explicit solution is presented in the particular,
paradigmatic cases of a constant crossed field and of a monochromatic wave with
circular and with linear polarization.",0801.1751v2
2008-03-13,Very Special (de Sitter) Relativity,"The effects of a non-vanishing value for the cosmological constant in the
scenario of Lorentz symmetry breaking recently proposed by Cohen and Glashow
(which they denote as Very Special Relativity) are explored and observable
consequences are pointed out.",0803.1949v1
2008-04-07,Dynamically broken Anti-de Sitter action for gravity,"Due to a suitable Higgs mechanism, a standard Anti-de Sitter gauge theory
becomes spontaneously broken. The resulting Lorentz invariant gravitational
action includes the Hilbert-Einstein term of ordinary Einstein-Cartan gravity
with cosmological constant, plus contributions quadratic in curvature and
torsion, and a scalar Higgs sector.",0804.1129v1
2008-06-25,On Brownian motion in ideal gas and related principles,"Brownian motion of particle interacting with atoms of ideal gas is discussed
as a key problem of kinetics lying at the border between ``dead'' systems like
the Lorentz gas or formal constructs of conceptual Boltzmannian kinetics and
actual ``alive'' systems like mere gas possessing scaleless (1/f) fluctuations
in their kinetic characteristics (e.g. in diffusuvity and mobility of the
``Brownian particle'').",0806.4157v1
2008-08-11,The complementary group of proper motions of the Minkowski metric in an arbitrary dimension space,"It is shown that the Poincare group which is a semidirect product of the
group of translations and the Lorentz group, is not a single physicaly
important group of proper motions of Minkowski metric. The complementary group
of proper motions of the metric in a class of noninertial reference system has
been found.",0808.1473v2
2008-08-12,Doubly special relativity and translation invariance,"We propose a new interpretation of doubly special relativity (DSR) based on
the distinction between the momentum and the translation generators in its
phase space realization. We also argue that the implementation of DSR theories
does not necessarily require a deformation of the Lorentz symmetry, but only of
the translation invariance.",0808.1628v1
2008-10-27,"Comment on ""Spin and Orbital Angular Momentum in Gauge Theories"" by X. S. Chen et. al. (PRL100, 232002 (2008))","The individual parts of the total angular momentum operator in interacting
theories cannot satisfy the canonical angular momentum commutation rule,
including those proposed in the above paper. Furthermore, the operators in the
new proposal a) are non-local in general gauge, b) do not have proper Lorentz
transformation properties, and c) do not have any known physical measurements.",0810.4913v1
2008-10-29,Generating Functional for Bound States in QED,"The manifestly Lorentz covariant formulation of quantum electrodynamics
disregards Coulomb instantaneous interaction and its consequence -
instantaneous bound states (IBS's). In this article we consider the way of
construction the IBS generating functional using the operator generalization of
the initial data in the Dirac Hamiltonian approach to QED.",0810.5199v1
2008-11-05,Charge Conjugation from Space-Time Inversion,"We show that the CPT group of the Dirac field emerges naturally from the PT
and P (or T) subgroups of the Lorentz group.",0811.0842v1
2008-11-27,On the History of Geometrization of Space-time: From Minkowski to Finsler Geometry,"The article is a tribute to Hermann Minkowski leading from his geometry of
numbers to an attempt at using Finsler geometry for a break of Lorentz
invariance.",0811.4529v1
2008-12-08,Equations of electromagnetism in some special anisotropic spaces,"We show that anisotropy of the space naturally leads to new terms in the
expression of Lorentz force, as well as in the expressions of currents.",0812.1513v1
2009-01-14,Hall Effect in spinor condensates,"We consider a neutral spinor condensate moving in a periodic magnetic field.
The spatially dependent magnetic field induces an effective spin dependent
Lorentz force which in turn gives rise to a spin dependent Hall effect.
Simulations of the Gross-Pitaevskii equation quantify the Hall effect. We
discuss possible experimental realizations.",0901.1969v2
2009-02-16,A Note on T-dualities in the Pure Spinor Heterotic String,"In this note we study the preservation of the classical pure spinor BRST
constraints under super T-duality transformations. We also determine the
invariance of the one-loop conformal invariance and of the local gauge and
Lorentz anomalies under the super T-dualities.",0902.2729v2
2009-02-25,The Relativistic Electrodynamics Least Action Principles Revisited: New Charged Point Particle and Hadronic String Models Analysis,"The classical relativistic least action principle is revisited from the
vacuum field theory approach. New physically motivated versions of relativistic
Lorentz type forces are derived, a new relativistic hadronic string model is
proposed and analyzed in detail.",0902.4400v1
2009-03-09,Galilean Isometries,"We introduce three nested Lie algebras of infinitesimal `isometries' of a
Galilei space-time structure which play the r\^ole of the algebra of Killing
vector fields of a relativistic Lorentz space-time. Non trivial extensions of
these Lie algebras arise naturally from the consideration of
Newton-Cartan-Bargmann automorphisms.",0903.1641v1
2009-03-16,Self-Dual $\mathcal N$ = 8 Supergravity as a Closed String Field Theory in Twistor Space,"A Closed string field theory action is formulated for $\mathcal N$ =8
self-dual supergravity which is off-shell and Lorentz covariant. The bosonic
truncation in the quantum field theory limit gives the Plebanski type of action
in the super space.",0903.2872v1
2009-03-23,Einstein's Apple and Relativity's Gravitational Field,"The foundations of Einstein's first (1907) principle of equivalence are
explored and their consequences are stated in terms of invariance under
generalized Lorentz transformations, first explored by Hessenberg.",0903.3768v2
2009-04-13,Fermions in (Anti) de Sitter Gravity in Four Dimensions,"Fermions in (anti) de Sitter gravity theory in four dimensions are
considered. Especially we propose new fermion actions to derive a Weyl or
Majorana fermion action if we break the AdS (dS) group to the Lorentz group in
curved spacetime.",0904.1936v3
2009-04-23,A Note on Quasi-Riemannian Gravity with Higher Derivatives,"Quasi-Riemannian theories of gravity have smaller gauge groups acting on the
tangent spacetime than the full Lorentz group. Among others, the spatial
rotation group can be gauged to obtain spacetime asymmetric gravity with
general covariance. We may introduce `spatial' higher-derivative interactions
exclusively to improve ultraviolet behavior with unitarity.",0904.3593v1
2009-04-23,The Mass of the Neutrinos,"In the theory of the Dirac equation and in the standard model, the neutrino
is massless. Both these theories use Lorentz invariance. In modern approaches
however, spacetime is no longer smooth, and this modifies special relativity.
We show how such a modification throws up the mass of the (electron) neutrino.",0904.3639v3
2009-05-12,Relativistic Ladder Operators for the Three-Dimensional Harmonic Oscillator,"The quantum constraint equations for a relativistic three-dimensional
harmonic oscillator are shown to find concise expression in terms of Lorentz
covariant ladder operators. These ladder operators consist of two conjugate
4-vectors that are each constrained to generate three linearly independent
combinations of ladder operator components for raising and lowering the
eigenstates of the oscillator. Correspondence to the Schr\""{o}dinger equation
for the harmonic oscillator in the non-relativistic limit is demonstrated.",0905.1750v1
2009-05-24,Endpoint bounds for a generalized {R}adon transform,"We prove that convolution with affine arclength measure on the curve
parametrized by $h(t) := (t,t^2,...,t^n)$ is a bounded operator from
$L^p(\mathbb{R}^n)$ to $L^q(\mathbb{R}^n)$ for the full conjectured range of
exponents, improving on a result due to M. Christ. We also obtain nearly sharp
Lorentz space bounds.",0905.3926v1
2009-07-13,Relativistic Stern-Gerlach Interaction in an RF Cavity,"The general expression of the Stern-Gerlach force is deduced for a
relativistic spin-1/2 particle which travels inside a time varying magnetic
field. This result was obtained either by means of two Lorentz boosts or
starting from Dirac's equation. Then, the utilization of this interaction for
attaining the spin states separation is reconsidered in a new example using a
new radio-frequency arrangement.",0907.2161v1
2009-07-16,Distribution Fitting 1. Parameters Estimation under Assumption of Agreement between Observation and Model,"The methods for parameter estimation under assumption of agreement between
observation and model are reviewed. The distribution parameters are obtained
for one set of experimental data by using different estimation methods under
assumption of Gauss-Laplace theoretical distribution. The results are presented
and discussed.",0907.2829v1
2009-07-17,Tests of CPT,"The ongoing experimental efforts in the high energy and high precision
communities keep providing evidence for CPT, a fundamental symmetry holding in
any local Lorentz invariant theory. We suggest possible interconnections
between different CPT violating parameters. Specifically, the very precise test
of CPT in the $K^0-\bar K^0$ system suggests--though definitely does not
imply--that CPT violations in other observable parameters (mass, width, charge,
magnetic moments, etc.) are much smaller than the directly measured bounds.",0907.3088v1
2009-08-24,Chiral Perturbation Theory: Introduction and Recent Results in the One-Nucleon Sector,"We provide an introduction to the basic concepts of chiral perturbation
theory and discuss some recent developments in the manifestly Lorentz-invariant
formulation of the one-nucleon sector.",0908.3425v1
2009-08-30,On the Perturbative Expansion around a Lifshitz Point,"The quantum Lifshitz model provides an effective description of a quantum
critical point. It has been shown that even though non--Lorentz invariant, the
action admits a natural supersymmetrization. In this note we introduce a
perturbative framework and show how the supersymmetric structure can be used to
greatly simplify the Feynman rules and thus the study of the model.",0908.4429v1
2009-10-11,A note on relativistic rocketry,"In the context of special relativity, we discuss the specific impulse of a
rocket whose exhaust jet consists of massive and/or massless particles. This
work generalizes previous results and corrects some errors of a recently
published paper by U. Walter. (The errors stem from the omission of a Lorentz
factor.)",0910.1965v2
2009-10-21,Theoretical and phenomenological aspects of theories with massive gravitons,"In this thesis, we study three aspects of theories with massive gravitational
waves. In the first part, we review to problems and issues of theories with
massive gravitons before introducing models where Lorentz invariance is
spontaneously broken by the vacuum expectation value of four scalar fields. In
the second part, we discuss three aspects of these models: instantaneous
interaction, spherically vacuum solutions and cosmological perturbations.",0910.4066v1
2009-11-01,Some Properties of Chiral Dotted Spinor Superfields,"Chiral superfields with multiple dotted Lorentz spinor indices (`dotspinors')
are important in the analysis of supersymmetry breaking through the mechanisms
of Cybersusy. This paper describes the actions for massive dotspinors coupled
to supersymmetric gauge theory and to chiral matter. It analyzes the free
equations of motion and mass spectra for the case of unbroken supersymmetry.
The general form of the Cybersusy algebra for dotsupers with multiple indices
is also discussed briefly.",0911.0199v1
2009-11-25,Best approximation with wavelets in weighted Orlicz spaces,"Democracy functions of wavelet admissible bases are computed for weighted
Orlicz Spaces in terms of its fundamental function. In particular, we prove
that these bases are greedy if and only if the Orlicz space is a Lebesgue
space. Also, sharp embeddings for the approximation spaces are given in terms
of weighted discrete Lorentz spaces. For Lebesgue spaces the approximation
spaces are identified with weighted Besov spaces.",0911.4907v1
2010-01-28,First-Class Approaches to Massive 2-Forms,"Massive 2-forms are analyzed from the point of view of the Hamiltonian
quantization using the gauge-unfixing approach and respectively the
Batalin--Fradkin method. Both methods finally output the manifestly Lorentz
covariant path integral for 1- and 2-forms with Stueckelberg coupling.",1001.5146v1
2010-02-26,Coulomb collisional relaxation process of ion beams in magnetized plasmas,"An orbit following code is developed to calculate ion beam trajectories in
magnetized plasmas. The equation of motion (the Newton's equation) is solved
including the Lorentz force term and Coulomb collisional relaxation term.
Furthermore, a new algorithm is introduced by applying perturbation method
regarding the collision term as a small term. The reduction of computation time
is suggested.",1002.4906v1
2010-02-27,On the generalized continuity equation,"A generalized continuity equation extending the ordinary continuity equation
has been found using quanternions. It is shown to be compatible with Dirac,
Schrodinger, Klein-Gordon and diffusion equations. This generalized equation is
Lorentz invariant. The transport properties of electrons are found to be
governed by Schrodinger-like equation and not by the diffusion equation.",1003.0071v1
2010-03-18,On the Compatibility Between Quantum and Relativistic Effects in an Electromagnetic Bridge Theory,"The Dipolar Electromagnetic Source (DEMS) model, based on the Poynting Vector
Conjecture, conduces in Bridge Theory to a derivation of the Lorentz
transformation connecting pairs of events. The results prove a full
compatibility between quantum and relativistic effects.",1003.3861v1
2010-04-19,A spacetime with closed timelike geodesics everywhere,"In the present article we find a new class of solutions of Einstein's field
equations. It describes stationary, cylindrically symmetric spacetimes with
closed timelike geodesics everywhere outside the symmetry axis. These
spacetimes contain a magnetic field parallel to the axis, a perfect fluid with
constant density and pressure, and Lorentz invariant vacuum with energy density
represented by a negative cosmological constant.",1004.3235v1
2010-04-23,Liouville-Lifshitz theory in 3+1 dimensions,"We consider a four-dimensional theory in the z=3 Lifshitz context, with an
exponential (Liouville) potential. We determine the exact renormalized
potential of the theory and derive the non-perturbative relation between the
renormalized and bare couplings. In addition, we show that Lorentz symmetry is
naturally generated by quantum fluctuations in the infrared regime, and
conclude that the model can be relevant to High Energy Physics.",1004.4201v1
2010-04-28,Extensions of the Stein-Tomas theorem,"We prove an endpoint version of the Stein-Tomas restriction theorem, for a
general class of measures, and with a strengthened Lorentz space estimate. A
similar improvement is obtained for Stein's estimate on oscillatory integrals
of Carleson-Sj\""olin-H\""ormander type and some spectral projection operators on
compact manifolds, and for classes of oscillatory integral operators with
one-sided fold singularities.",1004.4948v1
2010-06-27,Global Forces in Eruptive Solar Flares: The Lorentz force Acting on the Solar Atmosphere and the Solar Interior,"We compute the change in the Lorentz force integrated over the outer solar
atmosphere implied by observed changes in vector magnetograms that occur during
large, eruptive solar flares. This force perturbation should be balanced by an
equal and opposite force perturbation acting on the solar photosphere and solar
interior. The resulting expression for the estimated force change in the solar
interior generalizes the earlier expression presented by Hudson, Fisher and
Welsch (CS-383, ASP, 221, 2008), providing horizontal as well as vertical force
components, and provides a more accurate result for the vertical component of
the perturbed force. We show that magnetic eruptions should result in the
magnetic field at the photosphere becoming more horizontal, and hence should
result in a downward (towards the solar interior) force change acting on the
photosphere and solar interior, as recently argued from an analysis of
magnetogram data by Wang and Liu (Astrophys. J. Lett. 716, L195, 2010). We
suggest the existence of an observational relationship between the force change
computed from changes in the vector magnetograms, the outward momentum carried
by the ejecta from the flare, and the properties of the helioseismic
disturbance driven by the downward force change. We use the impulse driven by
the Lorentz-force change in the outer solar atmosphere to derive an upper limit
to the mass of erupting plasma that can escape from the Sun. Finally, we
compare the expected Lorentz-force change at the photosphere with simple
estimates from flare-driven gasdynamic disturbances and from an estimate of the
perturbed pressure from radiative backwarming of the photosphere in flaring
conditions.",1006.5247v4
2010-07-04,Stability of de Sitter solutions sourced by dark spinors,"Cosmology of ELKO and Lorentz Invariant NSS has been investigated using
dynamical system method starting from the proposal of Boehmer et al
[arXiv:1003.3858]. Some different results have been obtained by a different
approach. The exact solutions described by fixed points of the dynamical system
and their stability have been discussed. Some stable solutions corresponding to
de Sitter universes have been obtained.",1007.0554v1
2010-07-30,Emergent Photons and Gravitons:The Problem of Vacuum Structure,"We discuss vacuum condensates associated with emergent QED and with torsion,
as well as the possible role of the Kodama wave function in quantum cosmology.",1008.0033v1
2010-08-25,Stability of the aether,"The requirements for stability of a Lorentz violating theory are analyzed. In
particular we conclude that Einstein-aether theory can be stable when its modes
have any phase velocity, rather than only the speed of light as was argued in a
recent paper.",1008.4351v2
2010-08-27,Lorentz violation and the deformed commutation relations as the consequences of Nonlocality,"A nonlocal interaction is not necessarily expressed by the deformation of
commutators, so the paper is withdrawn.",1008.4724v2
2010-08-30,Topological Hall Effect in Inhomogeneous Superconductors,"We propose a possible mechanism of topological Hall effect in inhomogeneous
superconducting states. In our scenario, the Berry phase effect associated with
spatially modulated superconducting order parameter gives rise to a fictitious
Lorentz force acting on quasiparticles. In the case of the
Fulde-Ferrell-Larkin-Ovchinnikov state, the topological Hall effect is detected
by applying an electromagnetic wave with a tuned wave number on a surface of
the system.",1008.5183v1
2010-10-26,Differential Invariants and Hidden Symmetry,"We describe some classes of PDE that display hidden symmetry, with reduced
equations having additional symmetry operators compared to the initial
equations. Relations between the concepts of hidden and conditional symmetry,
and between hidden symmetry and equivalence of classes of equations, is
discussed. In particular, we describe equations having hidden and conditional
symmetry under rotations and boosts in the Lorentz and Euclid groups.",1010.5313v2
2010-10-29,Translation invariance and doubly special relativity,"We propose a new interpretation of doubly special relativity based on the
distinction between the momenta and the translation generators in its phase
space realization. We also argue that the implementation of the theory does not
necessarily require a deformation of the Lorentz symmetry, but only of the
translation invariance.",1010.6262v1
2010-11-10,On the Interaction in Lattice Gauge Theory,"Haag's theorem states that if a quantum field theory is Lorentz invariant and
irreducible, there is no interaction picture. But if we construct quantum field
theory on a discrete lattice spacetime, its representation will be reducible
and the interaction picture will be restored again.",1011.2278v2
2010-11-12,Galilean currents and charges,"We derive the Noether currents and charges associated with an internal
galilean invariance---a symmetry recently postulated in the context of
so-called galileon theories. Along the way we clarify the physical
interpretation of the Noether charges associated with ordinary Galileo- and
Lorentz-boosts.",1011.3057v1
2010-12-12,"Asymptotic theory of relativistic, magnetized jets","The structure of a relativistically hot, strongly magnetized jet is
investigated at large distances from the source. Asymptotic equations are
derived describing collimation and acceleration of the externally confined jet.
Conditions are found for the transformation of the thermal energy into the
fluid kinetic energy or into the Poynting flux. Simple scalings are presented
for the jet collimation angle and Lorentz factors.",1012.2517v1
2011-01-24,An Angular Formalism for Spin One Half,"Understanding spin one half is a crucial issue in the De Broglie Bohm
framework. In this paper a concrete relativistic realization of spin one half
in terms of angular coordinates is developed. A Lagrange formulation is found,
equations of motion are derived, and Lorentz invariance is discussed.",1101.4619v2
2011-02-14,Relativity tests and their motivation,"Some motivations for Lorentz-symmetry tests in the context of quantum-gravity
phenomenology are reiterated. The description of the emergent low-energy
effects with the Standard-Model Extension (SME) is reviewed. The possibility of
constraining such effects with dispersion-relation analyses of collider data is
established.",1102.2923v1
2011-02-18,SIM(2) and supergraphs,"We construct Feynman rules and Supergraphs in SIM(2) superspace. To test our
methods we perform a one-loop calculation of the effective action of the SIM(2)
supersymmetric Wess-Zumino model including a term which explicitly breaks
Lorentz invariance. The renormalization of the model is also discussed.",1102.3856v1
2011-03-27,Extensions of Calabi's correspondence between minimal surfaces and maximal surfaces,"The main goal of this survey is to illustrate geometric applications of the
Poincar\'{e} Lemma to constant mean curvature equations. In 1970, Calabi
introduced the duality between minimal graphs in three dimensional Euclidean
space and maximal graphs in three dimensional Lorentz space. We construct two
extensions of Calabi's correspondence.",1103.5180v2
2011-06-28,Kinematics of deep inelastic scattering in leading order of the covariant approach,"We study the kinematics of deep inelastic scattering corresponding to the
rotationally symmetric distribution of quark momenta in the nucleon rest frame.
It is shown that rotational symmetry together with Lorentz invariance can in
leading order impose constraints on the quark intrinsic momenta. Obtained
constraints are discussed and compared with the available experimental data.",1106.5607v2
2011-07-28,Do Fermi-LAT observations imply very large Lorentz factors in GRB outflows ?,"Recent detections of GeV photons in a few GRBs by Fermi-LAT imply huge bulk
Lorentz factors to avoid a large gamma gamma optical depth at high energy.
Estimates can be as high as Gamma ~ 1000 in the most extreme cases. This puts
severe constraints on models of the central engine and the jet acceleration in
GRBs. These estimates are however obtained from a simplified single zone model.
We present here a more realistic calculation which takes into account the time,
space and direction dependent photon field existing in an outflow with several
relativistically moving emitting zones. The formalism is general and can be
applied to many models of the prompt GRB emission. We present results obtained
for a numerical implementation in the framework of the internal shock model. We
show that (i) the minimum Lorentz factor Gamma_min in bright LAT GRBs is
reduced by a factor ~ 2-3 compared to previous estimates if the GeV and MeV
emission are produced in the same region, and by an additional factor ~ 2-8 if
the GeV emission is produced at larger radii. We provide an improved
approximate formula for Gamma_min which is in good agreement with our numerical
results and can be directly applied to LAT GRB data; (ii) a delayed GeV onset
can be due to the time evolution of the opacity. As an illustration of these
two first results, we present a synthetic GRB that reproduces most features of
GRB 080916C with a mean Lorentz factor of ~ 340, an optically thin regime for
gamma gamma opacity at 3GeV in bin 'b', a variability timescale of 0.5s in the
MeV lightcurve and a delayed onset of ~ 5s of the GeV emission; (iii) the gamma
gamma opacity can smooth the short timescale variability in the GeV lightcurve.
This last result implies that the observed variability at high energy is not
necessarily a good test to distinguish between an internal and an external
origin for the GeV emission in GRBs. [abridged]",1107.5737v4
2011-08-05,A Holographic Flat Band,"We describe a novel implementation of non-relativistic fermions in AdS/CFT by
imposing Lorentz violating boundary conditions for a Dirac spinor in AdS4. The
dual boundary theory is scale invariant and exhibits a number of interesting
properties, including a dispersionless flat band of gapless excitations.",1108.1381v2
2011-09-27,Superluminal neutrinos at the OPERA?,"We argue that the recent measurement of the neutrino velocity to be higher
than the velocity of light could be due to violation of Lorentz invariance by
the muon neutrinos. This result need not undermine special-relativistic
foundational notions of causality.",1109.5749v2
2011-09-30,A Projective Interpretation of Some Doubly Special Relativity Theories,"A class of projective actions of the orthogonal group on the projective space
is being studied. It is shown that the Fock--Lorentz, and Magueijo--Smolin
transformations known as Doubly Special Relativity are such transformations.
The formalism easily lead to new type transformations.",1109.6891v1
2011-10-11,Electrodynamics with radiation reaction,"The self force of electrodynamics is derived from a scalar field. The
resulting equation of motion is free of all of the problems that plague the
Lorentz Abraham Dirac equation. The age-old problem of a particle in a constant
field is solved and the solution has intuitive appeal.",1110.2464v1
2011-10-11,Physical Degrees of Freedom for Gauge Fields and the Issue of Spin,"The conflict between the physical degrees of freedom of gauge bosons and the
Lorentz group irreps naturally used to describe their couplings to matter
fields are illustrated and discussed, and applied to issues of linear and
angular momentum.",1110.2533v1
2011-10-17,Could the OPERA setup send a bit of information faster than light?,"We argue that with the current experimental setup of the OPERA neutrino
experiment no `bit' of information faster than light was or could be sent, and
therefore no violation of Lorentz symmetry and/or causality was observed.",1110.3642v2
2011-12-15,Towards an ultra-stable optical sapphire cavity system for testing Lorentz invariance,"We present a design for an ultra-stable cryogenically cooled sapphire optical
cavity system, with fractional frequency stability better than 1 x 10^-16 at
one second integration time. We plan to use such ultra-stable cavities to
perform a test of the isotropy of light propagation at the 10^-20 level.",1112.3623v1
2012-02-19,A spatio-temporal description of the abrupt changes in the photospheric magnetic and Lorentz-force vectors during the 2011 February 15 X2.2 flare,"The active region NOAA 11158 produced the first X-class flare of Solar Cycle
24, an X2.2 flare at 01:44 UT on 2011 February 15. Here we analyze SDO/HMI
magnetograms covering a 12-hour interval centered at the time of this flare. We
describe the spatial distributions of the photospheric magnetic changes
associated with this flare, including the abrupt changes in the field vector,
vertical electric current and Lorentz force vector. We also trace these
parameters' temporal evolution. The abrupt magnetic changes were concentrated
near the neutral line and in two neighboring sunspots. Near the neutral line,
the field vectors became stronger and more horizontal during the flare and the
shear increased. This was due to an increase in strength of the horizontal
field components near the neutral line, most significant in the horizontal
component parallel to the neutral line but the perpendicular component also
increased in strength. The vertical component did not show a significant,
permanent overall change at the neutral line. The increase in total flux at the
neutral line was accompanied by a compensating flux decrease in the surrounding
volume. In the two sunspots near the neutral line the azimuthal flux abruptly
decreased during the flare but this change was permanent in only one of the
spots. There was a large, abrupt, downward vertical Lorentz force change during
the flare, consistent with results of past analyses and recent theoretical
work. The horizontal Lorentz force acted in opposite directions along each side
of neutral line, with the two sunspots at each end subject to abrupt torsional
forces. The shearing forces were consistent with field contraction and decrease
of shear near the neutral line, whereas the field itself became more sheared as
a result of the flux collapsing towards the neutral line from the surrounding
volume.",1202.4192v5
2012-03-11,On a no-go theorem for classical Maxwell-Lorentz electrodynamics in odd-dimensional worlds,"A non-existence theorem of classical electrodynamics in odd-dimensional
spacetimes is shown to be invalid. The source of the error is pointed out, and
is then demonstrated during the derivation of the fields generated by a
uniformly moving point source.",1203.2375v1
2012-06-05,"""Meta"" relativity: Against special relativity?","We introduce a Lorentz-covariant description of tachyons, free of
inconsistencies. Our approach is based on an appropriate extension of the
special relativity beyond the light barrier, owing to the freedom of
synchronization of distant clocks.",1206.0841v1
2012-06-16,On Lagrangian Theory for Rotating Charge Coupled to the Maxwell Field,"We justify the Hamilton least action principle for the Maxwell-Lorentz
equations with Abraham's rotating extended electron. The main novelty in the
proof is application of the variational Poincare equations on the Lie group
SO(3). The variational equations allow to derive the corresponding conservation
laws from general Noether theory of invariants.",1206.3641v1
2012-08-12,Tchebyshev's characteristic of rearrangement invariant space,"We introduce and investigate in this short article a new characteristic of
rearrangement invariant (r.i.) (symmetric) space, namely so-called Tchebychev's
characteristic. We reveal an important class of the r.i. spaces - so called
regular r. i. spaces and show that the majority of known r.i. spaces:
Lebesgue-Riesz, Grand Lebesgue Spaces, Orlicz, Lorentz and Marcinkiewicz r.i.
spaces are regular. But we construct after several examples of r.i. spaces
without the regular property.",1208.2393v1
2012-09-04,On thermalization in gamma-ray burst jets and the peak energies of photospheric spectra,"The low energy spectral slopes of the prompt emission of most gamma-ray
bursts (GRBs) are difficult to reconcile with radiatively efficient optically
thin emission models irrespective of the radiation mechanism. An alternative is
to ascribe the radiation around the spectral peak to a thermalization process
occurring well inside the Thomson photosphere. This quasi-thermal spectrum can
evolve into the observed non-thermal shape by additional energy release at
moderate to small Thomson optical depths, which can readily give rise to the
hard spectral tail. The position of the spectral peak is determined by the
temperature and Lorentz factor of the flow in the termalization zone, where the
total number of photons carried by the jet is established. To reach
thermalization, dissipation alone is not sufficient and photon generation
requires an efficient emission/absorption process in addition to scattering. We
perform a systematic study of all relevant photon production mechanisms
searching for possible conditions in which thermalization can take place. We
find that a significant fraction of the available energy should be dissipated
at intermediate radii, $\sim 10^{10}$-- a few$\times 10^{11}$ cm and the flow
there should be relatively slow: the bulk Lorentz factor could not exceed a few
tens for all but the most luminous bursts with the highest $\Epk$-s. The least
restrictive constraint for successful thermalization, $\Gamma\lesssim 20$, is
obtained if synchrotron emission acts as the photon source. This requires,
however, a non-thermal acceleration deep below the Thomson photosphere
transferring a significant fraction of the flow energy to relativistic
electrons with Lorentz factors between 10 and 100. Other processes require bulk
flow Lorentz factors of order of a few for typical bursts. We examine the
implications of these results to different GRB photospheric emission models.",1209.0763v2
2012-11-18,EPR's reality criterion and quantum realism,"We show that EPR's criterion of reality leads to contradictions in quantum
mechanics. When locality is assumed, an inequality involving only one particle
is violated, while when parameter and outcome dependence are assumed,
EPR-realism is shown to be not Lorentz invariant. Quantum mechanics is both
non-local and non-realistic.",1211.4270v2
2013-01-11,Reciprocity and the scattering matrix of waveguide modes,"The implications of the Lorentz reciprocity theorem for a scatterer connected
to waveguides with arbitrary modes, including degenerate, evanescent, and
complex modes, are discussed. In general it turns out that a matrix $CS$ is
symmetric, where $C$ is the matrix of generalized orthogonality coefficients,
and $S$ is the scattering matrix. Examples are given, including a scatterer
surrounded by waveguides or free space, and discontinuities of waveguides.",1301.2458v1
2013-02-28,Rayleigh-Taylor Instability in a Relativistic Fireball on a Moving Computational Grid,"We numerically calculate the growth and saturation of the Rayleigh-Taylor
instability caused by the deceleration of relativistic outflows with Lorentz
factor {\Gamma} = 10, 30, and 100. The instability generates turbulence whose
scale exhibits strong dependence on Lorentz factor, as only modes with angular
size smaller than 1/{\Gamma} can grow. We develop a simple diagnostic to
measure the kinetic energy in turbulent fluctuations, and calculate a ratio of
turbulent kinetic energy to thermal energy of .03 in the region affected by the
instability. Although our numerical calculation does not include magnetic
fields, we argue that small scale turbulent dynamo amplifies magnetic fields to
nearly this same fraction, giving a ratio of magnetic to thermal energy of ~
.01, to within a factor of two. The instability completely disrupts the contact
discontinuity between the ejecta and the swept up circumburst medium. The
reverse shock is stable, but is impacted by the Rayleigh-Taylor instability,
which strengthens the reverse shock and pushes it away from the forward shock.
The forward shock front is unaffected by the instability, but Rayleigh-Taylor
fingers can penetrate of order 10% of the way into the energetic region behind
the shock during the two-shock phase of the explosion. We calculate afterglow
emission from the explosion and find the reverse shock emission peaks at a
later time due to its reduced Lorentz factor and modified density and pressure
at the shock front. These calculations are performed using a novel numerical
technique that includes a moving computational grid. The moving grid is
essential as it maintains contact discontinuities to high precision and can
easily evolve flows with extremely large Lorentz factors.",1302.7306v3
2013-04-13,Global strong solution to Maxwell-Dirac equations in 1+1 dimensions,"The Maxwell-Dirac equations with nonzero charge mass in one space dimension
are studied under the Lorentz gauge condition. The global existence and
uniqueness of solution in $C([0,+\infty);L^2(R^1))\times C_b(R^1 \times
[0,\infty))$ for initial value problem of Maxwell-Dirac equations are proved.",1304.3790v1
2013-05-08,Supergauge theories in aether superspace,"Within the superfield method we extend the formulation of the
Lorentz-breaking aether superspace for supergauge theories, both in three- and
in four-dimensional cases.",1305.1812v2
2013-07-05,Self-dual Maxwell-Chern-Simons solitons from a Lorentz-violating model,"Self-dual abelian Higgs system, involving both the Maxwell and Chern-Simons
terms are obtained from Carroll-Field-Jackiw theory by dimensional reduction.
Bogomol'nyi-type equations are studied from theoretical and numerical point of
view. In particular we show that the solutions of these equations are
Nielsen-Olesen vortices with electric charge.",1307.1734v1
2013-07-17,"Covariant basis induced by parity for the $(j,0)\oplus (0,j)$ representation","In this work, we build a covariant basis for operators acting on the
$(j,0)\oplus(0,j)$ Lorentz group representations. The construction is based on
an analysis of the covariant properties of the parity operator, which for these
representations transforms as the completely temporal component of a
symmetrical tensor of rank $2j$. The covariant properties of parity involve the
Jordan algebra of anti commutators of the Lorentz group generators which unlike
the Lie algebra is not universal. We make the construction explicit for
$j=1/2,1$ and $3/2$, reproducing well-known results for the $j=1/2$ case. We
provide an algorithm for the corresponding calculations for arbitrary $j$. This
covariant basis provides an inventory of all the possible interaction terms for
gauge and non-gauge theories of fields for these representations. In
particular, it supplies a single second rank antisymmetric structure, which in
the Poincar\'e projector formalism implies a single Pauli term arising from
gauge interactions and a single (free) parameter $g$, the gyromagnetic factor.
This simple structure predicts that for an elementary particle in this
formalism all multipole moments, $Q^{l}_{E}$ and $Q^{l}_{M}$, are dictated by
the complete algebraic structure of the Lorentz generators and the value of
$g$. We explicitly calculate the multipole moments, for arbitrary $j$ up to
$l=8$. Comparing with results in the literature we find that only the electric
charge and magnetic moment of a spin $j$ particle are independent of the
Lorentz representation under which it transforms, all higher multipoles being
representation dependent. Finally we show that the propagation of the
corresponding spin $j$ waves in a electromagnetic background is causal.",1307.4711v3
2013-07-19,The Feynman $i ε$ in String Theory,"The Feynman $i\varepsilon$ is an important ingredient in defining
perturbative scattering amplitudes in field theory. Here we describe its analog
in string theory. Roughly one takes the string worldsheet to have Lorentz
signature when a string is going on-shell although it has Euclidean signature
generically.",1307.5124v1
2013-07-19,Finite one-loop radiative corrections in the Lorentz- and CPT-violating QED extension,"We report on our current progress in the study of finite one-loop radiative
corrections in the minimal Lorentz- and CPT-violating QED extension.",1307.5331v1
2013-10-18,Obtaining bounds from ultra-high energy cosmic rays in isotropic modified Maxwell theory,"This article reviews the methods used to obtain a two-sided bound on
isotropic modified Maxwell theory from experimental data of ultra high-energy
cosmic rays in 2008. The bound is updated with results from the HEGRA
experiment.",1310.5159v1
2013-10-20,The GRW flash theory: a relativistic quantum ontology of matter in space-time?,"John Bell proposed an ontology for the GRW modification of quantum mechanics
in terms of flashes occurring at space-time points. The paper spells out the
motivation for this ontology, enquires into the status of the wave-function in
it, critically examines the claim of its being Lorentz-invariant and considers
whether it is a parsimonious, but nevertheless physically adequate ontology.",1310.5308v1
2013-12-20,"Second order theory of $(j,0)\oplus (0,j)$ single high spins as Lorentz tensors","We show that higher order differential equations and matrix spinor calculus
are completely avoidable in the description of pure high spin-$j$ Weinberg-Joos
states, $(j,0)\oplus (0,j)$. The case is made on the example of
$(3/2,0)\oplus(0,3/2)$, for the sake of concreteness and without loss of
generality. Namely, we use as a vehicle for the aforementioned covariant single
spin-$3/2$ description the antisymmetric tensor of second rank with Dirac
spinor components, $\Psi_{[\mu\nu]}=B_{[\mu\nu]}\otimes\psi$. The
$(3/2,0)\oplus(0,3/2)$ sector of interest is tracked down in two steps. First
we search for spin-$3/2$ by means of a covariant spin projector constructed
from the Casimir invariants of the Poincar\'e algebra, and then we identify the
wanted irreducible representation space by means of a momentum independent
(static) projector designed on the basis of the Casimir invariants of the
Lorentz algebra. The latter projectors unambiguously identify any irreducible
$so(1,3)$ subspace of any Lorentz tensor and without rising the order of the
differential equation. The method proposed correctly reproduces the
electromagnetic multipole moments earlier calculated for single spin-$3/2$
particles in treating it in the standard way as eight dimensional spinor. We
furthermore calculate Compton scattering off the pure spin-$3/2$ under
discussion, and show that the differential cross section satisfies unitarity in
forward direction for a gyromagnetic ratio of $g=2/3$. Suggesting possible
validity of Belinfante's conjecture for pure spin-states, while the natural
value of $g=2$ seems more likely to characterize the highest spins in the
Rarita-Schwinger representation spaces. The scheme straightforwardly extends to
any $(j,0)\oplus (0,j)$ Weinberg-Joos state and brings the advantage of
avoiding rectangular matrix couplings between states of different spins,
replacing them by simple Lorentz contractions.",1312.5811v1
2013-12-07,An application of two-spinors calculus to quantum field and quantum mechanics problems,"This paper describes the Lorentz two-spinors proposing to use them instead of
Dirac four-spinors and quaternions.",1312.6655v1
2014-07-03,Isgur-Wise functions and unitary representations of the Lorentz group : the meson case j = 1/2,"We pursue the group theoretical method to study Isgur-Wise functions. We
apply the general formalism, formerly applied to the baryon case j^P = 0^+ (for
\Lambda_b -> \Lambda_c \ell \nu), to mesons with j^P = 1/2^-, i.e.
$\overline{B} -> D(D^{(*)})\ell\nu. In this case, more involved from the
angular momentum point of view, only the principal series of unitary
representations of the Lorentz group contribute. We obtain an integral
representation for the IW function xi(w) with a positive measure, recover the
bounds for the slope and the curvature of xi(w) obtained from the
Bjorken-Uraltsev sum rule method, and get new bounds for higher derivatives. We
demonstrate also that if the lower bound for the slope is saturated, the
measure is a delta-function, and xi(w) is given by an explicit elementary
function. Inverting the integral formula, we obtain the measure in terms of the
IW function, allowing to formulate criteria to decide if a given ansatz for the
Isgur-Wise function is compatible or not with the sum rule constraints.
Moreover, we have obtained an upper bound on the IW function valid for any
value of w. We compare these theoretical constraints to a number of forms for
\xi(w) proposed in the literature. The ""dipole"" function \xi(w) =
(2/(w+1))^(2c) satisfies all constraints for c \geq 3/4, while the QCD Sum Rule
result including condensates does not satisfy them. Special care is devoted to
the Bakamjian-Thomas relativistic quark model in the heavy quark limit and to
the description of the Lorentz group representation that underlies this model.
Consistently, the IW function satisfies all Lorentz group criteria for any
explicit form of the meson Hamiltonian at rest.",1407.1001v2
2014-07-13,Ricci solitons in three-dimensional paracontact geometry,"We completely describe paracontact metric three-manifolds whose Reeb vector
field satisfies the Ricci soliton equation. While contact Riemannian (or
Lorentz\-ian) Ricci solitons are necessarily trivial, that is, $K$-contact and
Einstein, the paracontact metric case allows nontrivial examples. Both
homogeneous and inhomogeneous nontrivial three-dimensional examples are
explicitly described. Finally, we correct the main result of [AGAG-D-13-00189],
concerning three-dimensional normal paracontact Ricci solitons.",1407.3458v1
2014-07-21,On the effective action of the vacuum photon splitting in Lorentz violating QED through Krein space,"The finding of an explicit effective action describing amplitude of photon
triple splitting is investigated through Krein space quantization and quantum
metric fluctuation. Using the derivative expansion method, the one-loop
radiative corrections from Lorentz- and CPT- violating extended Krein QED shows
that it is not possible to find a nonzero effective action.",1407.5608v1
2014-07-22,Gödel solution in the bumblebee gravity,"Here, we consider a gravity theory involving a spontaneous Lorentz symmetry
breaking called the bumblebee model. We show that, at certain values of the
bumblebee field, the G\""odel metric is consistent within this theory.",1407.5985v1
2014-08-14,Implications of Lorentz violation on Higgs-mediated lepton flavor violation,"The lepton flavor violating decay of the Higgs boson $H\to l_Al_B$ is studied
within two qualitatively different extensions of the Yukawa sector: one
renormalizable and the other nonrenormalizable; both incorporating Lorentz
violation in a model-independent fashion. These extensions are characterized by
Yukawa-like matrices, the former by a constant Lorentz 2-tensor $Y^{AB}_{\mu
\nu}$, whereas the latter by a constant Lorentz vector $Y^{AB}_\mu$. It is
found that the experimental constraints on the decays $l_A\to l_B\gamma$
severely restrict lepton flavor violating Higgs signals in the renormalizable
scenario. In this context, it is found that $BR(H\to \mu^\pm e^\mp)$ and
$BR(H\to \tau^\pm \mu^\mp)$ cannot be larger than $10^{-18}$ and $10^{-11}$,
respectively. In the nonrenormalizable scenario, transitions mediated by the
Higgs or the $Z$ gauge boson are induced at tree level, and we find mild
restrictions on lepton flavor violation. Using the experimental limits on the
three-body decays $l_A \to l_B \bar{l}_Cl_C$ to constraint the vector
$Y^{AB}_\mu$, it is found that the branching ratio for the decays $H\to \mu^\pm
e^\mp$ is of about $4\times 10^{-9}$, more important, a branching ratio of
$7\times 10^{-4}$ is found for the $\tau^\pm \mu^\mp$ mode. Accordingly, the
decay $H \to \tau^\pm \mu^\mp$ could be at the reach of future measurements.
The lepton flavor violating decays of the $Z$ gauge boson were also studied. In
the renormalizable scenario, it was found the undetectable branching ratios
$BR(Z\to \mu^\pm e^\mp)<5.7\times 10^{-21}$ and $BR(Z\to \tau^\pm
\mu^\mp)<2.0\times 10^{-12}$. In the nonrenormalizable scenario, it was found
that $BR(Z\to \mu^\pm e^\mp)<0.67\times 10^{-12}$ and $BR(Z\to \tau^\pm
\mu^\mp)<1.12\times 10^{-7}$. Although the latter branching ratio is relatively
large, it still could not be within the range of future measurements.",1408.3307v3
2014-08-22,Construction of Maximal Hypersurfaces with Boundary Conditions,"We construct maximal hypersurfaces with a Neumann boundary condition in
Minkowski space via mean curvature flow. In doing this we give general
conditions for long time existence of the flow with boundary conditions with
assumptions on the curvature of a the Lorentz boundary manifold.",1408.5309v2
2014-09-06,Astrophysical Constraints on the Bumblebee Model,"In this work the Bumblebee model for spontaneous Lorentz symmetry breaking is
considered in the context of spherically symmetric astrophysical bodies. A
discussion of the modified equations of motion is presented and constraints on
the parameters of the model are perturbatively obtained.",1409.2022v2
2014-09-18,Magnetic moments of $J^P = {3\over 2}^-$ baryons in QCD,"The magnetic moments of the low lying, negative parity, spin-3/2 baryons are
calculated within the light cone QCD sum rules method. The contributions coming
from the positive parity, spin-3/2 baryons, as well as from the positive and
negative parity spin-1/2 baryons are eliminated by constructing combinations of
various invariant amplitudes corresponding to the coefficients of the different
Lorentz structures.",1409.5252v1
2014-09-29,Borderline gradient continuity of minima,"The gradient of any local minimiser of functionals of the type $$ w \mapsto
\int_\Omega f(x,w,Dw)\,dx+\int_\Omega w\mu\,dx, $$ where $f$ has $p$-growth,
$p>1$, and $\Omega \subset \mathbb R^n$, is continuous provided the optimal
Lorentz space condition $\mu \in L(n,1)$ is satisfied and $x\to f(x, \cdot)$ is
suitably Dini-continuous.",1409.8122v1
2014-10-09,Translation and homothetical surfaces in Euclidean space with constant curvature,"We study surfaces in Euclidean space constructed by the sum of two curves or
that are graphs of the product of two functions. We consider the problem to
determine all these surfaces with constant Gauss curvature. We extend the
results to non degenerate surfaces in Lorentz-Minkowski space.",1410.2512v1
2014-11-30,The lightlike geometry of marginally trapped surfaces in Minkowski space-time,"The lightlike geometry of codimension two spacelike submanifolds in
Lorentz-Minkowski space has been developed in [Izumiya, S. and Romero Fuster,
M. C. Selecta Mathematica (NS), 13 23--55 (2007)] which is a natural Lorentzian
analogue of the classical Euclidean differential geometry of hypersurfaces. In
this paper we investigate a special class of surfaces (i.e., marginally trapped
surfaces) in Minkowski space-time from the view point of the lightlike
geometry.",1412.0169v1
2014-12-22,An end-point global gradient weighted estimate for quasilinear equations in non-smooth domains,"A weighted norm inequality involving $A_1$ weights is obtained at the natural
exponent for gradients of solutions to quasilinear elliptic equations in
Reifenberg flat domains. Certain gradient estimates in Lorentz-Morrey spaces
below the natural exponent are also obtained as a consequence of our analysis.",1412.7057v1
2015-01-06,Foldy-Wouthuysen transformation for non-Hermitian Hamiltonians,"Two Non-Hermitian fermion models are proposed and analyzed by using
Foldy-Wouthuysen transformations. One model has Lorentz symmetry breaking and
the other has a non-Hermitian mass term. It is shown that each model has real
energies in a given region of parameter space, where they have a locally
conserved current.",1501.01232v2
2015-04-01,Magnetic moments of negative parity heavy baryons in QCD,"The magnetic moments of the negative parity, spin-1/2 baryons containing
single heavy quark are calculated. The pollution that occur from the
transitions between positive and negative parity baryons are removed by
constructing the sum rules from different Lorentz structures.",1504.00172v1
2015-04-20,"Approximation by (p,q)-Lorentz polynomials on a compact disk","In this paper, we introduce a new analogue of Lorentz polynomials based on
(p,q)-integers and we call it as (p,q)-Lorentz polynomials. We obtain
quantitative estimate in the Voronovskaja's type thoerem and exact orders in
simultaneous approximation by the complex (p,q)-Lorentz polynomials of degree
n, where q > p > 1 attached to analytic functions in compact disks of the
complex plane.",1504.05093v1
2015-06-03,Babel of Units. The Evolution of Units Systems in Classical Electromagnetism,"We recount the history of development of units systems in electrodynamics,
and fully derive how each system is constructed. Done for Electromagnetic
(emu), Electrostatic (esu), Gaussian, a variant-Gaussian, Heaviside-Lorentz,
and SI systems. The article fills in large gaps in standard textbook treatments
of units.",1506.01951v1
2015-06-08,Earth's Inner Core dynamics induced by the Lorentz force,"Seismic studies indicate that the Earth's inner core has a complex structure
and exhibits a strong elastic anisotropy with a cylindrical symmetry. Among the
various models which have been proposed to explain this anisotropy, one class
of models considers the effect of the Lorentz force associated with the
magnetic field diffused within the inner core. In this paper we extend previous
studies and use analytical calculations and numerical simulations to predict
the geometry and strength of the flow induced by the poloidal component of the
Lorentz force in a neutrally or stably stratified growing inner core, exploring
also the effect of different types of boundary conditions at the inner core
boundary (ICB). Unlike previous studies, we show that the boundary condition
that is most likely to produce a significant deformation and seismic anisotropy
is impermeable, with negligible radial flow through the boundary. Exact
analytical solutions are found in the case of a negligible effect of buoyancy
forces in the inner core (neutral stratification), while numerical simulations
are used to investigate the case of stable stratification. In this situation,
the flow induced by the Lorentz force is found to be localized in a shear layer
below the ICB, which thickness depends on the strength of the stratification,
but not on the magnetic field strength. We obtain scaling laws for the
thickness of this layer, as well as for the flow velocity and strain rate in
this shear layer as a function of the control parameters, which include the
magnitude of the magnetic field, the strength of the density stratification,
the viscosity of the inner core, and the growth rate of the inner core. We find
that the resulting strain rate is probably too small to produce significant
texturing unless the inner core viscosity is smaller than about $10^{12}$ Pa.s.",1506.02392v1
2015-06-18,On Lorentz spacetimes of constant curvature,"We describe in parallel the Lorentzian homogeneous spaces
$G=\mathrm{PSL}(2,\mathbb{R})$ and $\mathfrak{g}=\mathfrak{psl}(2,\mathbb{R})$,
and review some recent results relating the geometry of their quotients by
discrete groups.",1506.05663v1
2015-06-30,Einstein's Third Postulate,"Einstein's own demonstration of time dilation taken from his book with L.
Infeld (1938) is analyzed. His ingenious circumnavigation of an apparent
discrepancy between clock synchronisation and Lorentz transformation is
discussed.",1506.09070v2
2015-09-11,Theory of electromagnetic reactions in light nuclei,"We briefly review the theory for electromagnetic reactions in light nuclei
based on the coupled-cluster formulation of the Lorentz integral transform
method. Results on photodisintegration reactions of 22O and 40Ca are reported
on and preliminary calculations on the Coulomb sum rule for 4He are discussed.",1509.03681v1
2015-10-28,"Constructing metric gravity's N-body non-linear Lagrangian from iterative, linear algebraic scaling equations","A method for constructing metric gravity's N-body Lagrangian is developed
which uses iterative, liner algebraic euqations which enforce invariance
properties of gravity --- exterior effacement, interior effacement, and the
time dilation and Lorentz contraction of matter under boosts. The method is
demonstrated by obtaining the full 1/c^4 order Lagrangian, and a combination of
exterior and interior effacement enforcement permits construction of the full
Schwarzschild temporal and spatial metric potentials.",1510.08471v1
2015-11-06,"Generalised relativistic Ohm's laws, extended gauge transformations and magnetic linking","Generalisations of the relativistic ideal Ohm's law are presented that
include specific dynamical features of the current carrying particles in a
plasma. Cases of interest for space and laboratory plasmas are identified where
these generalisations allow for the definition of generalised electromagnetic
fields that transform under a Lorentz boost in the same way as the real
electromagnetic fields and that obey the same set of homogeneous Maxwell's
equations.",1511.02142v1
2015-11-08,The relativity of Colour,"By attaching three anticommuting Lorentz scalar (colour) property coordinates
to space-time, with an appropriate extended metric, we unify gravity with
chromodynamics: gauge transformations then just correspond to coordinate
transformations in the enlarged spacetime-property space.",1511.02412v2
2015-11-17,A replacement of the Lorentz law for the shape of the spectral lines in the infrared region,"We propose a new phenomenological law for the shape of the spectral lines in
the infrared, which accounts for the exponential decay of the extinction
coefficient in the high frequency region, observed in many spectra. We apply
this law to the measured infrared spectra of LiF, NaCl and MgF$_2$, finding a
good agreement, over a wide range of frequencies.",1511.05426v1
2016-03-13,On invariants for the Poincare equations and applications,"We extend the Noether theory of invariants to the Poincare equations. We
apply this extension to the Maxwell-Lorentz equations coupled to the Abraham
rotating extended electron with the configuration space SO(3).",1603.03997v1
2016-03-28,Demystifying the twistor construction of composite operators in N=4 super-Yang-Mills theory,"We explain some details of the construction of composite operators in N=4 SYM
that we have elaborated earlier in the context of Lorentz harmonic chiral (LHC)
superspace. We give a step-by-step elementary derivation and show that the
result coincides with the recent hypothesis put forward in arXiv:1603.04471
within the twistor approach. We provide the appropriate LHC-to-twistors
dictionary.",1603.08478v1
2016-04-01,Multimode coherent states and the Lorentz-invariant mass of light pulses,"The total mass of noncollinear photons forming diverging light pulses is
defined and found explicitly. Both classical and quantum derivations are
presented. The quantum derivation is based on the use of multimode coherent
states, and links between parameters of these states and those of the classical
field strength are established.",1604.00227v3
2016-04-28,CPT-symmetry studies with antihydrogen,"Various approaches to physics beyond the Standard Model can lead to small
violations of CPT invariance. Since CPT symmetry can be measured with ultrahigh
precision, CPT tests offer an interesting phenomenological avenue to search for
underlying physics. We discuss this reasoning in more detail, comment on the
connection between CPT and Lorentz invariance, and review how CPT breaking
would affect the (anti)hydrogen spectrum.",1604.08419v1
2016-07-21,Positronium and Muonium 1S-2S Laser Spectroscopy as a Probe for the Standard-Model Extension,"We present the status and the prospects of the ongoing efforts to improve the
measurements of the 1S-2S transition in positronium and muonium. These purely
leptonic systems represent ideal objects to test bound-state QED to high
precision and the Standard-Model Extension.",1607.06398v1
2016-08-09,Calculating the Finite-Speed-of-Light Effect in Atom Gravimeters with General Relativity,"This work mainly presents a relativistic analytical calculating method for
the finite speed-of-light effect in atom gravimeters, which can simplify the
deriva- tion and give a more complete expression for the associated correction.",1609.06164v1
2016-10-13,High Energy Effects of Noncommutative Spacetime Geometry,"In this paper, we endeavour to obtain a modified form of the Foldy-Wouthuysen
and Cini-Toushek transformations by resorting to the noncommutative nature of
space-time geometry, starting from the Klein-Gordon equation. Also, we obtain a
shift in the energy levels due to noncommutativity and from these results a
limit for the Lorentz factor in the ultra-relativistic case has been derived in
conformity with observations",1610.06415v1
2017-02-15,High Order Numerical Integrators for Relativistic Charged Particle Tracking,"In this paper, we extend several time reversible numerical integrators to
solve the Lorentz force equations from second order accuracy to higher order
accuracy for relativistic charged particle tracking in electromagnetic fields.
A fourth order algorithm is given explicitly and tested with numerical
examples. Such high order numerical integrators can significantly save the
computational cost by using a larger step size in comparison to the second
order integrators.",1702.04486v1
2017-02-24,On the Possible Trajectories of Particles with Spin. III. Particles in the Stationary Homogeneous Electric Field,"The behavior of spinning particles in the stationary homogeneous electric
field is considered and trajectories are found for various spin orientations.
We study the acceleration of spinning particles by an electric field, as well
as the electric and magnetic deflection in constant homogeneous fields. It is
shown that the classical Lorentz-Einstein theory of motion of charged particles
is a special case of the proposed theory",1703.09760v1
2018-04-20,Torsional Topological Invariants,"Making use of the SO(3,1) Lorentz algebra, we derive in this paper two series
of Gauss-Bonnet type identities involving torsion, one being of the Pontryagin
type and the other of the Euler type. Two of the six identities involve only
torsional tensorial entities and are purely torsional topological invariants.",1804.07440v2
2018-11-29,Latest results on astroparticle physics with H.E.S.S,"The High Energy Spectroscopic System (H.E.S.S.) is pursuing a rich
observational program in astroparticle physics. The latest results from
H.E.S.S. on the search for dark matter towards the Galactic Center and dwarf
galaxies, the test of Lorentz invariance, and the measurement of the cosmic-ray
electron spectrum are presented.",1811.12241v1
2019-05-03,On The Björling Problem For Lightlike Curves In $\mathbb{R}^4_1$,"In this work we provide necessary and sufficient conditions for the existence
of a minimal timelike strip in Lorentz-Minkowski space $\mathbb{R}^4_1$
containing a given lightlike curve and prescribed normal bundle. We also
discuss uniqueness of solutions.",1905.01196v2
2020-07-14,Restriction inequalities for the hyperbolic hyperboloid,"In this article we establish new inequalities, both conditional and
unconditional, for the restriction problem associated to the hyperbolic, or
one-sheeted, hyperboloid in three dimensions, endowed with a Lorentz-invariant
measure. These inequalities are unconditional (and optimal) in the bilinear
range $q > \frac{10}{3}$.",2007.06990v1
2013-08-29,Testing Relativity with High-Energy Astrophysical Neutrinos,"The recent observation of high-energy astrophysical neutrinos can be used to
constrain violations of Lorentz invariance emerging from a quantum theory of
gravity. We perform threshold and Cherenkov analyses that improve existing
bounds by factors ranging from about a million to 10^{20}.",1308.6344v1
2014-03-01,Octet negative parity to octet positive parity electromagnetic transitions in light cone QCD,"Light cone QCD sum rules for the electromagnetic transition form factors
among positive and negative parity octet baryons are derived. The unwanted
contributions of the diagonal transitions among positive parity octet baryons
are eliminated by combining the sum rules derived from different Lorentz
structures. The $Q^2$ dependence for the transversal and longitudinal helicity
amplitudes are studied.",1403.0096v1
2014-01-21,Universal Gravitation as Lorentz-covariant Dynamics,"This paper has been withdrawn by the author after further work showed the
proposed theoretical approach cannot fit planetary perihelion precession data.
As presented, the theory doesn't fit gravitational light deflection by the sun
either, but a straightforward theoretical change does remedy that; however a
proper fit to planetary perihelion precession data is not thus obtained. The
author's stated philosophical objections to the Einstein equation can be dealt
with in a markedly different way -- a new paper entitled ""Unique Einstein
Gravity from Feynman's Lorentz Condition"" has been submitted. Einstein's
equivalence principle implies that the acceleration of a particle in a
""specified"" gravitational field is independent of its mass. While this is
certainly true to great accuracy for bodies we observe in the Earth's
gravitational field, a hypothetical body of mass comparable to the Earth's
would perceptibly cause the Earth to fall toward it, which would feed back into
the strength as a function of time of the Earth's gravitational field affecting
that body. In short, Einstein's equivalence principle isn't exact, but is an
approximation that ignores recoil of the ""specified"" gravitational field, which
sheds light on why general relativity has no clearly delineated native
embodiment of conserved four-momentum. Einstein's 1905 relativity of course
doesn't have the inexactitudes he unwittingly built into GR, so it is natural
to explore a Lorentz-covariant gravitational theory patterned directly on
electromagnetism, wherein a system's zero-divergence overall stress-energy,
including all gravitational feedback contributions, is the source of its
gravitational tensor potential. Remarkably, that alone completely determines
Lorentz-covariant gravity's interaction with any conservative system of locally
interacting classical fields; no additional ""principles"" of any kind are
required. The highly intricate equation for the gravitational interaction
contribution to such a system's Lagrangian density is only amenable to solution
by successively refined approximation, however.",1403.2685v2
2014-03-17,Managing gamma_5 in Dimensional Regularization and ABJ Anomaly,"An integral representation is proposed for the trace involving gamma_5 in
dimensional regularization. Lorentz covariance is preserved. ABJ anomaly
naturally follows. The Local Functional Equation associated to x-dependent
chiral transformations is verified.",1403.4212v3
2014-03-30,Energy-momentum tensors for non-commutative Abelian Proca field,"We study two different possibilities of constructing the energy-momentum
tensors for non-commutative Abelian Proca field, by using (i) general Noether
theorem and (ii) coupling to a weak external gravitational field. Both
energy-momentum tensors are not traceless due to the violation of Lorentz
invariance in non-commutative spaces. In particular, we show that the obtained
energy density of the latter case coincides exactly with that of obtained by
Dirac quantization method.",1403.7723v1
2016-11-10,Lorentzian manifolds with transitive conformal group,"We study pseudo-Riemanniasn manifolds $(M,g)$ with transitive group of
conformal transformation which is essential, i.e. does not preserves any metric
conformal to $g$. All such manifolds of Lorentz signature with non exact
isotropy representation of the stability subalgebra are described. A
construction of essential conformally homogeneous manifolds with exact isotropy
represenatation is given. Using spinor formalism, we prove that it provides all
4-dimensional non conformally flat Lorentzian 4-dimensional manifolds with
transitive essentially conformal group.",1611.03447v1
2016-11-08,Equations of motion for charged particles in strong laser fields,"Starting from the Dirac equation coupled to a classical radiation field a set
of equations of motion for charged quasi-particles in the classical limit for
slowly varying radiation and matter fields is derived. The radiation reaction
term derived in the paper is the Abraham-Lorentz-Dirac term.",1611.03892v1
2017-01-01,Behavior of the Gaussian curvature of timelike minimal surfaces with singularities,"In the 3-dimensional Lorentz-Minkowski space we prove that the sign of the
Gaussian curvature of any timelike minimal surface is determined by the
degeneracy and the orientations of the two null curves that generate the
surface. Moreover, we also investigate the behavior of the Gaussian curvature
near singular points of a timelike minimal surface which admits some kind of
singular points.",1701.00238v2
2017-04-25,On the spherical convexity of quadratic functions,"In this paper we study the spherical convexity of quadratic functions on
spherically convex sets. In particular, conditions characterizing the spherical
convexity of quadratic functions on spherical convex sets associated to the
positive orthants and Lorentz cones are given.",1704.07665v3
2001-07-04,Standardizing distance and time,"Einstein's Equivalence Principle is used with the electromagnetic spectrum to
translate meters and seconds into radians and seconds. Based on a unique
geometric relationship, a new transformation of velocities and a changed
Lorentz transformation result. The physical angle of parallelism is quantified.
The way we measure distance and time is standardized, constructing a theory of
time and geometry to the universe.",0107005v1
2008-07-04,Astroelectrons as Non-Dual Field Solutions,"The continuous charge density of the r^{-4} radial astroelectron is found
analytically from the Maxwell-Lorentz equations. The electric charge is not a
basic concept, but is the nonlinear field distribution associated with the
elementary self-energy density. The Poisson equation for the unified field
carrier in non-dual electrodynamics locally relates the post-Coulomb potential
with the energy-charge density. The local Maxwell equations maintain the global
overlap of nonlocal electric energy-charges in the undivided Universe.",0807.0832v1
2008-07-11,A Lorentz invariant formulation of the Yang-Mills theory with gauge invariant ghost field Lagrangian,"A new formulation of the Yang-Mills theory which allows a manifestly
covariant gauge fixing accompanied by a gauge invariant ghost field interaction
is proposed. The gauge condition selects a unique representative in the class
of gauge equivalent configurations.",0807.1795v1
2008-07-31,Spontaneous Lorentz symmetry breaking and cosmological constant,"This paper has been withdrawn by the authors due to need of essential
revision.",0807.4999v2
2009-12-18,Dynamical behavior of Darboux curves,"In 1872 G. Darboux defined a family of curves on surfaces of R^3 which are
preserved by the action of the Mobius group and share many properties with
geodesics. Here we characterize these curves under the view point of Lorentz
geometry and prove some general properties and make them explicit them on
simple surfaces, retrieving results of Pell (1900) and Santalo (1941).",0912.3749v1
2012-01-17,An integral transform on a cylinder and the twistor correspondence,"Twistor correspondences for R-invariant indefinite self-dual conformal
structures on R^4 are established explicitly. These correspondences are written
down by using a natural integral transform from functions on a two dimensional
cylinder to functions on the flat Lorentz space R^{1,2} which is related to the
wave equation and the Radon transform. A general method on the twistor
construction of indefinite self-dual 4-spaces and indefinite Einstein-Weyl
3-spaces are also summarized.",1201.3450v1
2012-01-19,Constraining the High-Energy Emission from Gamma-ray Bursts with Fermi,"We examine 288 GRBs detected by the Fermi Gamma-ray Space Telescope's
Gamma-ray Burst Monitor (GBM) that fell within the field-of-view of Fermi's
Large Area Telescope (LAT) during the first 2.5 years of observations, which
showed no evidence for emission above 100 MeV. We report the photon flux upper
limits in the 0.1-10 GeV range during the prompt emission phase as well as for
fixed 30 s and 100 s integrations starting from the trigger time for each
burst. We compare these limits with the fluxes that would be expected from
extrapolations of spectral fits presented in the first GBM spectral catalog and
infer that roughly half of the GBM-detected bursts either require spectral
breaks between the GBM and LAT energy bands or have intrinsically steeper
spectra above the peak of the {\nu}F{\nu} spectra (Epk). In order to
distinguish between these two scenarios, we perform joint GBM and LAT spectral
fits to the 30 brightest GBM-detected bursts and find that a majority of these
bursts are indeed softer above Epk than would be inferred from fitting the GBM
data alone. Approximately 20% of this spectroscopic subsample show
statistically significant evidence for a cut-off in their high-energy spectra,
which if assumed to be due to {\gamma}{\gamma} attenuation, places limits on
the maximum Lorentz factor associated with the relativistic outflow producing
this emission. All of these latter bursts have maximum Lorentz factor estimates
that are well below the minimum Lorentz factors calculated for LAT- detected
GRBs, revealing a wide distribution in the bulk Lorentz factor of GRB outflows
and indicating that LAT-detected bursts may represent the high end of this
distribution.",1201.3948v1
2013-09-04,"Multi-Time Equations, Classical and Quantum","Multi-time equations are evolution equations involving several time
variables, one for each particle. Such equations have been considered for the
purpose of making theories manifestly Lorentz invariant. We compare their
status and significance in classical and quantum physics.",1309.1103v2
2013-09-17,The invariants of the electromagnetic field,"We present a constructive proof that all gauge invariant Lorentz scalars in
Electrodynamics can be expressed as a function of the quadratic ones.",1309.4185v2
2013-09-17,Renormalization in QED and QFT with a Lorentz- and CPT-violating backgrounds,"The general features of renormalization and the renormalization group in QED
and in general quantum field theories in curved spacetime with additional
Lorentz- and CPT-violating background fields are reviewed.",1309.4190v1
2013-09-23,Covariant Photon Quantization in the SME,"The Gupta Bleuler quantization procedure is applied to the SME photon sector.
A direct application of the method to the massless case fails due to an
unavoidable incompleteness in the polarization states. A mass term can be
included into the photon lagrangian to rescue the quantization procedure and
maintain covariance.",1309.5890v1
2015-12-03,Characterizations of umbilic points of isometric immersions in Riemannian and Lorentzian manifolds,"Several characterizations of umbilic points of submanifolds in arbitrary
Riemannian and Lorentzian manifolds are given. As a consequence, we obtain new
characterizations of spheres in the Euclidean space and of hyperbolic spaces in
the Lorentz-Minkowski space. We also prove the Lorentzian version of a
classical result by Cartan.",1512.01211v2
2015-12-10,Norms supporting the Lebesgue differentiation theorem,"A version of the Lebesgue differentiation theorem is offered, where the $L^p$
norm is replaced with any rearrangement-invariant norm. Necessary and
sufficient conditions for a norm of this kind to support the Lebesgue
differentiation theorem are established. In particular, Lorentz, Orlicz and
other customary norms for which Lebesgue's theorem holds are characterized.",1512.03202v1
2016-05-04,Composite operators and form factors in N=4 SYM,"We construct the most general composite operators of N = 4 SYM in Lorentz
harmonic chiral ($\approx$ twistor) superspace. The operators are built from
the SYM supercurvature which is nonpolynomial in the chiral gauge
prepotentials. We reconstruct the full nonchiral dependence of the
supercurvature. We compute all tree-level MHV form factors via the LSZ
redcution procedure with on-shell states made of the same supercurvature.",1605.01386v1
2016-05-05,Physical states in Quantum Einstein-Cartan Gravity,"The definition of physical states is the main technical issue of canonical
approaches towards Quantum Gravity. In this work, we outline how those states
can be found in Einstein-Cartan theory via a continuum limit and they are given
by finite dimensional representations of the Lorentz group.",1605.01544v1
2016-05-18,Variations on Gromov's open-dense orbit theorem,"We investigate several situations where the local homogeneity of a geometric
structure on a dense open subset of a manifold implies the local homogeneity
everywhere. This results in a strengthening of the conclusions in Gromov's
open-dense orbit theorem. In particular, we show that any smooth closed
3-dimensional Lorentz manifold with a topologically transitive isometric action
must be locally homogeneous.",1605.05755v1
2016-08-15,Note on the speed of GW150914 in gravity's rainbow,"Without breaking Lorentz invariance, we investigate the speed of graviton in
event GW150914 by using the modified dispersion relation from gravity's
rainbow. The proper range of the parameter in the modified dispersion relation
is determined by taking into account the gap between the speed of the graviton
and that obtained from event GW150914.",1608.04247v1
2016-08-26,"Geometry of historical epoch, the Alexandrov's problem and non-Gödel quantum time machine","The new quantum principle of a time machine that is not using a smooth
timelike loops in Lorentz manifolds is described. The proposed time machine is
based on the destruction of interference of quantum superposition states in the
Wheeler superspace.",1608.08532v2
2016-12-29,Analysis of radial excitations of octet baryons in QCD sum rules,"Using the QCD sum rules method, we estimate the mass and residues of the
first radial excitations of octet baryons. The contributions coming from the
ground state baryons are eliminated by constructing the linear combinations of
the sum rules corresponding to different Lorentz structures. Our predictions of
the masses of the first radial excitations of octet baryons are in good
agreement with the data.",1612.09345v1
2016-12-30,General Wigner Rotations in $D$ Dimensions,"We construct general Wigner rotations for both massive and massless particles
in $D$-dimensional spacetime. We work out the explicit expressions of these
Wigner rotations for arbitrary Lorentz transformations. We study the relation
between the electromagnetic gauge invariance and the non-uniqueness of Wigner
rotation.",1612.09392v2
2017-06-20,A sharp version of the Hörmander multiplier theorem,"We provide an improvement of the H\""ormander multiplier theorem in which the
Sobolev space $L^r_s(\mathbb R^n)$ with integrability index $r$ and smoothness
index $s>n/r$ is replaced by the Sobolev space with smoothness $s$ built upon
the Lorentz space $L^{n/s,1}(\mathbb R^n)$.",1706.06507v1
2017-10-02,"Born's Rule, EPR, and the Free Will Theorem","Many physicists believe that the EPR experiment exhibits instantaneous
non-local effects. I argue below that an application of Born's Rule to EPR
shows no such instantaneous effects and that EPR is consistent with full
Lorentz invariance. I then discuss how it is possible to understand the EPR
correlations for non-commuting spin components without recourse to non-local
effects. Finally, I use these results to discuss the Free Will Theorem, which I
formulate in a new way.",1710.00868v1
2017-10-11,Holographic Scattering Amplitudes,"Inspired by ancient astronomy, we propose a holographic description of
perturbative scattering amplitudes, as integrals over a `celestial sphere'.
Since Lorentz invariance, local interactions, and particle propagations all
take place in a four-dimensional space-time, it is not trivial to accommodate
them in a lower-dimensional `celestial sphere'. The details of this task will
be discussed step by step, resulting in the Cachazo-He-Yuan (CHY) and similar
scattering amplitudes, thereby providing them with a holographic non-string
interpretation.",1710.04302v1
2018-01-18,Prompt gamma-ray emission of GRB 170817A associated to GW 170817: A consistent picture,"The short GRB 170817A associated to the first detection of gravitation waves
from a Binary Neutron Star (BNS) merger was in many ways unusual. Possible
explanations are emission from a cocoon or cocoon break out, off-axis view of a
structured or uniform jet, and on-axis ultra-relativistic jet with reduced
density and Lorentz factor. Here we use a phenomenological model of shock
evolution and synchrotron/self-Compton emission to simulate the prompt emission
of GRB 170817A and to test above proposals. We find that synchrotron emission
from a mildly relativistic cocoon with a Lorentz factor of 2-3, as considered
in the literature, generates a too soft, too long, and too bright prompt
emission. Off-axis view of an structured jet with a Lorentz factor of about 10
can reproduce observations, but needs a very efficient transfer of kinetic
energy to electrons in internal shocks, which is disfavored by particle in cell
simulations. We also comment on cocoon breakout as a mechanism for generation
of the prompt gamma-ray. A relativistic jet with a Lorentz factor of about 100
and a density lower than typical short GRBs seems to be the most plausible
model and we conclude that GRB 170817A was intrinsically faint. Based on this
result and findings of relativistic magnetohydrodynamics simulations of BNS
merger in the literature we discuss physical and astronomical conditions, which
may lead to such faint short GRBs. We identify small mass difference of
progenitor neutron stars, their old age and reduced magnetic field, and
anti-alignment of spin-orbit angular momentum induced by environmental
gravitational disturbances during the lifetime of the BNS as causes for the
faintness of GRB 170817A. We predict that BNS mergers at lower redshifts
generate on average fainter GRBs.",1801.06124v3
2018-10-21,Inclusion between generalized Stummel classes and other function spaces,"We refine the definition of generalized Stummel classes and study inclusion
properties of these classes. We also study the inclusion relation between
Stummel classes and other function spaces such as generalized Morrey spaces,
weak Morrey spaces, and Lorentz spaces. In addition, we show that these
inclusions are proper. Our results extend some previous results in \cite{CRR,
RZ}.",1810.08952v1
2019-06-03,Noncommutative Gravity and the Standard-Model Extension,"Noncommutative geometry has become popular mathematics for describing
speculative physics beyond the Standard Model. Noncommutative QED has long been
known to fit within the framework of the Standard-Model Extension (SME). We
argue in this work that noncommutative gravity also fits within the SME
framework.",1906.01008v1
2019-06-23,Highlights from the 7 year High Energy Starting Event sample in Icecube,"Here we outline the main highlights from the 7 year High Energy Starting
Events (HESE) event sample. The next new physics search using astrophysical
neutrino flavor data is described, where we reach the Planck scale for the
first time.",1906.09623v1
2019-07-18,Maximal Tests in Minimal Gravity,"Recent tests have generated impressive reach in the gravity sector of the
Standard-Model Extension. This contribution to the CPT'19 proceedings
summarizes this progress and maps the structure of work in the gravity sector.",1907.08106v1
2019-07-24,Status and Prospects for CPT Tests with the ALPHA Experiment,"A primary goal of the ALPHA experiment at CERN is to perform precise tests of
CPT symmetry. Here, we report on the significant progress made in recent years
on antihydrogen spectroscopy and the outlook for the future.",1907.10727v1
2019-07-29,Dynamics of solar Coronal Mass Ejections: forces that impact their propagation,"We investigate the Sun-Earth dynamics of a set of 38 well-observed Coronal
Mass Ejections(CMEs) using data from the STEREO, SOHO missions and WIND
instrument. We seek to quantify the relative contributions of Lorentz force and
aerodynamic drag on their propagation. The CMEs are 3D reconstructed using the
Graduated Cylindrical Shell(GCS) model to derive observed CME parameters.Using
a microphysical prescription of the drag coefficient,we find that solar wind
aerodynamic drag adequately accounts for the dynamics of the fastest CMEs from
as low as 3.5 Rs. For relatively slower CMEs, however, we find that when the
drag-based model is initiated below the distances ranging from 12 to 50 Rs,the
observed CME trajectories cannot be accounted for.This suggests that
aerodynamic drag force dominates the dynamics of slower CMEs only above these
heights.To investigate CME dynamics below the heights where aerodynamic drag
dominates, we consider the Torus Instability model for the driving Lorentz
force. We find that for fast CMEs,Lorentz forces become negligible in
comparison to aerodynamic drag as early as 3.5-4 Rs.For slow CMEs, however,
they become negligible only by 12-50 Rs.This justifies the success of the
drag-only model for fast CMEs. In case of slow CMEs, the Lorentz force is only
slightly smaller than the drag force even beyond 12-50 Rs.For these slow
events,our results suggest that some of the magnetic flux carried by CMEs might
be expended in expansion or heating. These dissipation effects might be
important in describing the propagation of slower CMEs. To the best of our
knowledge,this is the first systematic study in this regard using a diverse CME
sample. A physical understanding of the forces that affect CME propagation and
how they compare with each other at various heliocentric distances is an
important ingredient in building tools for describing and predicting CME
trajectories.",1907.12673v1
2019-09-30,Field emission with relativistic effects in a magnetic field,"The work concerns relativistic effects and the influence of an external
magnetic field on the transmission coefficient. The Fowler-Nordheim equation
has been relativistically generalized and effect of the Lorentz contraction of
a potential barrier at the metal-vacuum interface has been found. Influence of
the magnetic field parallel to a metal surface on the transmission coefficient
is taken into account when cB < E.",1910.00447v1
2019-10-15,Progress Towards Ramsey Hyperfine Spectroscopy in ASACUSA,"This proceedings contribution reports on progress on the design of a
Ramsey-type spectrometer that will be used for the spectroscopy of the
ground-state hyperfine structure of both hydrogen and deuterium.",1910.06609v1
2020-01-16,Transverse Force Imaging,"While twist-2 GPDs allow for a determination of the distribution of partons
on the transverse plane, twist-3 GPDs contain quark-gluon correlations that
provide information about the average transverse color Lorentz force acting on
quarks. As an example, we use the nonforward generalization of $g_T(x)$, to
illustrate how twist-3 GPDs can provide transverse position information about
that force.",2001.05978v1
2020-02-15,Absence of Hall effect due to Berry curvature in phase space,"Transverse current due to Berry curvature in phase space is formulated based
on the Boltzmann equations with the semiclassical equations of motion for an
electron wave packet. It is shown that the Hall effect due to the phase space
Berry curvature is absent because the contributions from ""anomalous velocity""
and ""effective Lorentz force"" are completely cancelled out.",2002.08162v2
2020-12-23,"Dispersion of Light Traveling through the Interstellar Space, Induced and Intrinsic Lorentz Invariance Violation","Theoretical models and experimental observations suggest that gamma-ray
bursts (GRB) and high-energy neutrino bursts travelling through the
interstellar space may reach the Earth at different speeds. We propose and
study in details the mechanism i), which always exists, where GRB are slowed
down due to the dispersion of light in the interstellar medium. In addition to
the standard media such as electrons and photons as CMB, we consider the medium
with invisible axions. The amount of GRB delays in different media are
calculated in details utilizing a novel technique in QFT by using the hitherto
known or estimated densities of particles in the space without introducing any
arbitrary parameter. Previously, the GRB delays have been interpreted as a sign
of Lorentz invariance violation by modifying the dispersion relation of Special
Relativity, which relates the energy, the momentum and the mass of a particle,
based on different mechanisms ii), such as a stringy spacetime foam, coming
from a quantum gravity effect and using an adjustable parameter. Obviously, all
the above-mentioned mechanisms i) and ii) are induced (seeming) Lorentz
invariance violations but not an intrinsic (genuine) one. The amount of GRB
delay due to the two aforementioned interpretations can be distinguished by
observing the time of arrival of light with different frequencies. Namely,
dispersion of light i) predicts that the higher energy GRB arrive the Earth
earlier, while in the other interpretations ii), they arrive later. We notice
that the needed amount for delay due to the dispersion of light shall have the
potential power to shed additional light on the microstructure of interstellar
media with respect to the densities of constituent particles and the origins of
their sources. Finally, we indicate the ways to detect the intrinsic Lorentz
invariance violation and to interpret them theoretically.",2101.00954v5
2021-01-07,Quantum power distribution of relativistic acceleration radiation: classical electrodynamic analogies with perfectly reflecting moving mirrors,"We find the quantum power emitted and distribution in $3+1$-dimensions of
relativistic acceleration radiation using a single perfectly reflecting mirror
via Lorentz invariance demonstrating close analogies to point charge radiation
in classical electrodynamics.",2101.02511v1
2021-01-14,Can the gamma-ray bursts travelling through the interstellar space be explained without invoking the drastic assumption of Lorentz invariance violation?,"Experimental observations indicate that gamma-ray bursts (GRB) and
high-energy neutrino bursts may travel at different speeds with a typical delay
measured at the order of hours or days. We discuss two potential
interpretations for the GRB delay: dispersion of light in interstellar medium
and violation of Lorentz invariance due to quantum gravitational fluctuations.
Among a few other media, we consider dispersion of light in an axion plasma,
obtaining the axion plasma frequency and the dispersion relation from quantum
field theory for the first time. We find that the density of axions inferred
from observations is far too low to produce the observed GRB delay. However, a
more precise estimation of the spatial distribution of axions is required for a
conclusive result. Other known media are also unable to account for the GRB
delay, although there remains uncertainties in the observations of the delays.
The interpretation in terms of Lorentz invariance violation and modified
dispersion relation suffers from its own problems: since the modification of
the dispersion relation should not be dependent on particle type, delays
between photons and neutrinos are hard to explain. Thus neither interpretation
is sufficient to explain the observations. We conclude that a crucial
difference between the two interpretations is the frequency dependence of the
propagation speed of radiation: in dispersive plasma the group speed increases
with higher frequency, while Lorentz invariance violation implies lower speed
at higher frequency. Future experiments shall resolve which one of the two
frequency dependencies of GRB is actually the case.",2101.05758v1
2021-01-13,"Comment on: ""On the Dirac oscillator subject to a Coulomb-type central potential induced by the Lorentz symmetry violation""","We analyze recent results on a Dirac oscillator. We show that the truncation
of the Frobenius series does not yield all the eigenvalues and eigenfunctions
of the radial equation. For this reason the eigenvalues reported by the authors
are useless and the prediction of allowed oscillator frequencies meaningless.",2101.06117v1
2012-05-20,A relativistic action-at-a-distance description of gravitational interactions?,"It is shown that certain aspects of gravitation may be described using a
relativistic action-at-a-distance formulation. The equations of motion of the
model presented are invariant under Lorentz transformations and agree with the
equations of Einstein's theory of General Relativity, at the first
Post-Newtonian approximation, for any number of interacting point masses.",1205.4417v1
2012-05-23,DiPerna-Lions flow for relativistic particles in an electromagnetic field,"We show the existence and uniqueness of a DiPerna-Lions flow for relativistic
particles subject to a Lorentz force in an electromagnetic field. The electric
and magnetic fields solves the linear Maxwell system in the void but for
singular initial conditions. As the corresponding force field is only in $L^2$,
we have to perform a careful analysis of the cancellations over a trajectory.",1205.5244v1
2017-05-04,Violation of causality in $f(T)$ gravity,"[Abridged] In its standard formulation, the $f(T)$ field equations are not
invariant under local Lorentz transformations, and thus the theory does not
inherit the causal structure of special relativity. A locally Lorentz covariant
$f(T)$ gravity theory has been devised recently, and this local causality
problem has been overcome. The nonlocal question, however, is left open. If
gravitation is to be described by this covariant $f(T)$ gravity theory there
are a number of issues that ought to be examined in its context, including the
question as to whether its field equations allow homogeneous G\""odel-type
solutions, which necessarily leads to violation of causality on nonlocal scale.
Here, to look into the potentialities and difficulties of the covariant $f(T)$
theories, we examine whether they admit G\""odel-type solutions. We take a
combination of a perfect fluid with electromagnetic plus a scalar field as
source, and determine a general G\""odel-type solution, which contains special
solutions in which the essential parameter of G\""odel-type geometries, $m^2$,
defines any class of homogeneous G\""odel-type geometries. We extended to the
context of covariant $f(T)$ gravity a theorem, which ensures that any
perfect-fluid homogeneous G\""odel-type solution defines the same set of G\""odel
tetrads $h_A^{~\mu}$ up to a Lorentz transformation. We also shown that the
single massless scalar field generates G\""odel-type solution with no closed
timelike curves. Even though the covariant $f(T)$ gravity restores Lorentz
covariance of the field equations and the local validity of the causality
principle, the bare existence of the G\""odel-type solutions makes apparent that
the covariant formulation of $f(T)$ gravity does not preclude non-local
violation of causality in the form of closed timelike curves.",1705.02226v2
2017-05-21,Gradient weighted norm inequalities for very weak solutions of linear parabolic equations with BMO coefficients,"In this paper, we prove the Lorentz space $L^{q,p}$-estimates for gradients
of very weak solutions to the linear parabolic equations with
$\mathbf{A}_q$-weights $$u_t-\operatorname{div}(A(x,t)\nabla
u)=\operatorname{div}(F),$$ in a bounded domain $\Omega\times
(0,T)\subset\mathbb{R}^{N+1}$, where $A$ has a small mean oscillation, and
$\Omega$ is a Lipchistz domain with a small Lipschitz constant.",1705.07438v1
2017-09-08,Lorentzian Goldstone modes shared among photons and gravitons,"It has long been known that photons and gravitons may appear as vector and
tensor Goldstone modes caused \ by spontaneous Lorentz invariance violation
(SLIV). Usually this approach is considered for photons and gravitons
separately. We develop the emergent electrogravity theory consisting of the
ordinary QED and the tensor field gravity model which mimics the linearized
general relativity in Minkowski spacetime. In this theory, Lorentz symmetry
appears incorporated into higher global symmetries of the length-fixing
constraints put on the vector and tensor fields involved, $A_{\mu }^{2}=\pm
M_{A}^{2}$ and $H_{\mu \nu }^{2}=\pm M_{H}^{2}$ ($M_{A}$ and $M_{H}$ are the
proposed symmetry breaking scales). We show that such a SLIV pattern being
related to breaking of global symmetries underlying these constraints induces
the massless Goldstone and pseudo-Goldstone modes shared among photon and
graviton. While for a vector field case the symmetry of the constraint
coincides with Lorentz symmetry $SO(1,3)$ of the electrogravity Lagrangian, the
tensor field constraint itself possesses much higher global symmetry $SO(7,3)$,
whose spontaneous violation provides a sufficient number of zero modes
collected in a graviton. Accordingly, while photon may only contain true
Goldstone modes, graviton appears at least partially composed from
pseudo-Goldstone modes rather than from pure Goldstone ones. When expressed in
terms of these modes, the theory looks essentially nonlinear and contains a
variety of Lorentz and $CPT$ violating couplings. However, all SLIV effects
turn out to be strictly cancelled in the lowest order processes that is
considered in some detail. How this emergent electrogravity theory could be
observationally differed from conventional QED and GR theories is also briefly
discussed.",1709.02736v2
2017-11-25,Photons in the Quantum World,"Einstein's photo-electric effect allows us to regard electromagnetic waves as
massless particles. Then, how is the photon helicity translated into the
electric and magnetic fields perpendicular to the direction of propagation?
This is an issue of the internal space-time symmetries defined by Wigner's
little group for massless particles. It is noted that there are three
generators for the rotation group defining the spin of a particle at rest. The
closed set of commutation relations is a direct consequence of Heisenberg's
uncertainty relations. The rotation group can be generated by three two-by-two
Pauli matrices for spin-half particles. This group of two-by-two matrices is
called SU(2), with two-component spinors. The direct product of two spinors
leads to four states leading to one spin-0 state and one spin-1 state with
three sub-states. The SU(2) group can be expanded to another group of
two-by-two matrices called SL(2,c), which serves as the covering group for the
group of Lorentz transformations. In this Lorentz-covariant regime, it is
possible to Lorentz-boost the particle at rest to its infinite-momentum or
massless state. Also in this SL(2,c) regime, there are four spin states for
each particle, as in the case of the Dirac equation. The direct product of two
SL(2,c) spinors thus leads sixteen states. Among them, four of them can be used
for the electromagnetic four-potential, and six for the Maxwell tensor. The
gauge degree of freedom is shown to be a Lorentz-boosted rotation. The
polarization of massless neutrinos is interpreted as a consequence of the gauge
invariance.",1711.09210v1
2018-03-13,Divergence free quantum field theory using a spectral calculus of Lorentz invariant measures,"This paper presents a spectral calculus for computing the spectrum of a
causal Lorentz invariant Borel complex measure on Minkowski space, thereby
enabling one to compute the density for such a measure with respect to Lebesque
measure. It is proved that the convolution of arbitrary causal Lorentz
invariant Borel measures exists and the product of such measures exists in a
wide class of cases. Techniques for their computation are presented. Divergent
integrals in quantum field theory (QFT) are shown to have a well defined
existence as Lorentz covariant measures. The case of vacuum polarization is
considered and the spectral vacuum polarization function is shown to have very
close agreement with the vacuum polarization function obtained using
dimensional regularization / renormalization in the timelike domain. Using the
spectral vacuum polarization function the exact Uehling potential function is
derived. The spectral running coupling constant is computed and is shown to
converge for all energies while the integral defining the running coupling
constant obtained using dimensional regularization / renormalization is shown
to diverge for all non-zero energies.",1803.05732v8
2018-06-09,On some Liouville type theorems for the stationary equations of MHD,"We prove several Liouville type results for the stationary Hall-MHD and MHD
equations. In particular, we show that the velocity and magnetic field,
belonging to some Lorentz spaces, must be zero.",1806.03427v2
2018-08-06,On Wigner function of a vortex electron,"We derive a relatively simple and Lorentz-invariant expression for a Wigner
function of a paraxial vortex electron described as a Laguerre-Gaussian wave
packet.",1808.01801v2
2018-12-30,"Beginnings of the Helicity Basis in the (S,0)+(0,S) Representations of the Lorentz Group","We write solutions of relativistic quantum equations explicitly in the
helicity basis for S=1/2 and S=1. We present the analyses of relations between
Dirac-like and Majorana-like field operators. Several interesting features of
bradyonic and tachyonic solutions are presented.",1901.01844v1
2019-01-09,Gradient estimates for nonlinear elliptic equations with first order terms,"We study existence and Lorentz regularity of distributional solutions to
elliptic equations with either a convection or a drift first order term. The
presence of such a term makes the problem not coercive. The main tools are
pointwise estimates of the rearrangements of both the solution and its
gradient.",1901.02673v2
2019-02-02,On some Liouville type Theorems for the stationary MHD and Hall-MHD equations,"We prove several Liouville type results for the stationary MHD and Hall-MHD
equations. In particular, we show that the velocity and magnetic field,
belonging to some Lorentz spaces or satisfying a priori decay assumption, must
be zero.",1902.00740v2
2019-03-03,Stochastic Electrodynamics: The Closest Classical Approximation to Quantum Theory,"Stochastic electrodynamics is the classical electrodynamic theory of
interacting point charges which includes random classical radiation with a
Lorentz-invariant spectrum whose scale is set by Planck's constant. Here we
give a cursory overview of the basic ideas of stochastic electrodynamics, of
the successes of the theory, and of its connections to quantum theory.",1903.00996v1
2019-08-28,"(2,0) Lagrangian Structures","By including an additional self-dual three-form we construct a Lorentz
invariant lagrangian for the abelian (2,0) tensor supermultiplet. The extra
three-form is a supersymmetry singlet and decouples from the (2,0) tensor
supermultiplet. We also present an interacting non-abelian generalization which
reproduces the equations of motion of [arXiv:1007.2982 [hep-th]] and can
describe some aspects of two interacting M5-branes.",1908.10752v2
2019-08-30,Asymptotic expansion of correlation functions for $\mathbb{Z}^d$ covers of hyperbolic flows,"We establish expansion of every order for the correlation function of
sufficiently regular observables of $\mathbb Z^d$ extensions of some hyperbolic
flows. Our examples include the $\mathbb Z^2$ periodic Lorentz gas and geodesic
flows on abelian covers of compact manifolds with negative curvature.",1908.11504v1
2019-11-06,The SME with gravity and explicit diffeomorphism breaking,"This overview looks at what happens when the Standard-Model Extension (SME)
is used to investigate gravity theories with explicit diffeomorphism breaking.
It is shown that when matter-gravity couplings are included, the SME generally
maintains consistency with the Bianchi identities, and it therefore provides a
useful phenomenological framework for investigating the effects of explicit
diffeomorphism breaking in gravity theories.",1911.02517v1
2019-11-01,The counting of Nambu-Goldstone bosons in a non-Hermitian field theory,"We demonstrate that the number of Nambu-Goldstone bosons is always equal to
the number of conserved currents inside the scenario of non-Hermitian field
theories with spontaneous symmetry breaking. This eliminates the redundancies
which normally appears in Hermitian field theories, specifically when the
Lagrangian under analysis violates explicitly the Lorentz symmetry.",1911.03230v2
2019-11-11,Multilinear Spherical Maximal Function,"In dimensions $n\ge 2$ we obtain $L^{p_1}(\mathbb R^n) \times\dots\times
L^{p_m}(\mathbb R^n)$ to $L^p(\mathbb R^n)$ boundedness for the multilinear
spherical maximal function in the largest possible open set of indices and we
provide counterexamples that indicate the optimality of our results. Moreover,
we obtain weak type and Lorentz space estimates as well as counterexamples in
the endpoint cases.",1911.04071v1
2019-11-15,Virial theorem and generalized momentum in quaternic quantum mechanics,"After a review on recent results on quaternic quantum mechanics
($\mathbb{H}$QM), we present further consistency tests that reinforce its
compatibility with the usual complex quantum mechanics ($\mathbb{C}$QM). The
novel results comprises the Virial theorem, the quantum quaternic Lorentz
force, the existence of a quaternic magnetic monopole and the redefinition of
the expectation value.",1911.06831v1
2019-11-21,Weak And Strong Boundedness For P-adic Fractional Hausdorff Operator And Its Commutator,"In this paper, boundedness of Hausdorff operator on weak central Morrey space
is obtained. Furthermore, we investigate the weak bounds of p- adic fractional
Hausdorff Operator on weighted p-adic weak Lebesgue Space. We also obtain the
sufficient condition of commutators of p-adic fractional Hausdorff Operator by
taking symbol function from Lipschitz space. Moreover, strong type estimates
for fractional Hausdorff Operator and its commutator on weighted p-adic Lorentz
space are also acquired.",1911.09392v1
2020-05-27,A regularity criterion in weak spaces to Boussinesq equations,"In this paper, we study regularity of weak solutions to the incompressible
Boussinesq equations in $\mathbb{R}^{3}\times (0,T)$. The main goal is to
establish the regularity criterion in terms of one velocity component and the
gradient of temperature in Lorentz spaces.",2005.14019v1
2020-06-25,The Formula for the Quasicentral Modulus in the Case of Spectral Measures on Fractals,"We prove a general ampliation homogeneity result for the quasicentral modulus
of an n-tuple of operators with respect to the (p,1) Lorentz normed ideal. We
use this to prove a formula involving Hausdorff measure for the quasicentral
modulus of n-tuples of commuting Hermitian operators the spectrum of which is
contained in certain Cantor-like self-similar fractals.",2006.14456v2
2020-07-24,Reference Frame Transformations and Quantization,"It has been said that Maxwell's theory of electromagnetic field is
relativistic as Einstein showed that these axioms of Maxwell are all Lorentz
invariant. We investigate some issues regarding these results.",2008.01517v1
2020-08-05,Local equilibrium in planar non interacting particle systems,"Particles are injected to a large planar rectangle through the boundary.
Assuming that the particles move independently from one another and the
boundary is also absorbing, we identify a set of abstract conditions which
imply the local equilibrium of the particle density in diffusive scaling limit.
We verify that our abstract conditions hold in two examples: iid random walks
and the periodic Lorentz process.",2008.01986v1
2020-09-10,Trace dynamics and division algebras: towards quantum gravity and unification,"We have recently proposed a Lagrangian in trace dynamics at the Planck scale,
for unification of gravitation, Yang-Mills fields, and fermions. Dynamical
variables are described by odd-grade (fermionic) and even-grade (bosonic)
Grassmann matrices. Evolution takes place in Connes time. At energies much
lower than Planck scale, trace dynamics reduces to quantum field theory. In the
present paper we explain that the correct understanding of spin requires us to
formulate the theory in 8-D octonionic space. The automorphisms of the octonion
algebra, which belong to the smallest exceptional Lie group $G_2$, replace
space-time diffeomorphisms and internal gauge transformations, bringing them
under a common unified fold. Building on earlier work by other researchers on
division algebras, we propose the Lorentz-weak unification at the Planck scale,
the symmetry group being the stabiliser group of the quaternions inside the
octonions. This is one of the two maximal subgroups of $G_2$, the other one
being $SU(3)$, the element preserver group of octonions. This latter group,
coupled with $U(1)_{em}$, describes the electro-colour symmetry, as shown
earlier by Furey. We predict a new massless spin one boson [the Lorentz boson]
which should be looked for in experiments. Our Lagrangian correctly describes
three fermion generations, through three copies of the group $G_2$, embedded in
the exceptional Lie group $F_4$. This is the unification group for the four
fundamental interactions, and it also happens to be the automorphism group of
the exceptional Jordan algebra. Gravitation is shown to be an emergent
classical phenomenon. Whereas at the Planck scale, there is present a quantised
version of the Lorentz symmetry, mediated by the Lorentz boson. We argue that
at sub-Planck scales, the self-adjoint part of the octonionic trace dynamics
bears a relationship with string theory in eleven dimensions.",2009.05574v4
2020-10-06,Testing a Data-driven Active Region Evolution Model with Boundary Data at Different Heights from a Solar Magnetic Flux Emergence Simulation,"A data-driven active region evolution (DARE) model has been developed to
study the complex structures and dynamics of solar coronal magnetic fields. The
model is configured with typical coronal environment of tenuous gas governed by
strong magnetic field, and thus its lower boundary is set at the base of the
corona, but driven by magnetic fields observed in the photosphere. A previous
assessment of the model using data from a flux emergence simulation (FES)
showed that the DARE failed to reproduce the coronal magnetic field in the FES,
which is attributed to the fact that the photospheric data in the FES has a
very strong Lorentz force and therefore spurious flows are generated in the
DARE model. Here we further test the DARE by using three sets of data from the
FES sliced at incremental heights, which correspond to the photosphere, the
chromosphere and the base of the corona. It is found that the key difference in
the three sets of data is the extent of the Lorentz force, which makes the
data-driven model perform very differently. At the two higher levels above the
photosphere, the Lorentz force decreases substantially, and the DARE model
attains results in much better agreement with the FES, confirming that the
Lorentz force in the boundary data is a key issue affecting the results of the
DARE model. However, unlike the FES data, the photospheric field from SDO/HMI
observations has recently been found to be very close to force-free. Therefore,
we suggest that it is still reasonable to use the photospheric magnetic field
as approximation of the field at the coronal base to drive the DARE model.",2010.02497v1
2020-10-12,Massless Particles in Higher Dimensions,"In spacetimes of any dimensionality, the massless particle states that can be
created and destroyed by a field in a given representation of the Lorentz group
are severely constrained by the condition that the invariant Abelian subgroup
of the little group must leave these states invariant. A number of examples are
given of the massless one-particle states that can be described by various
tensor and spinor-tensor fields, and a speculation is offered for the general
case.",2010.05823v1
2020-10-16,Optimality of function spaces for kernel integral operators,"We explore boundedness properties of kernel integral operators acting on
rearrangement-invariant (r.i.) spaces. In particular, for a given r.i. space
$X$ we characterize its optimal range partner, that is, the smallest r.i. space
$Y$ such that the operator is bounded from $X$ to $Y$. We apply the general
results to Lorentz spaces to illustrate their strength.",2010.08632v2
2020-11-12,Combined Lorentz symmetry: lessons from superfluid 3He,"We consider the possibility of the scenario in which the $P$, $T$ and Lorentz
symmetry of the relativistic quantum vacuum are all the combined symmetries.
These symmetries emerge as a result of the symmetry breaking of the more
fundamental $P$, $T$ and Lorentz symmetries of the original vacuum, which is
invariant under separate groups of the coordinate transformations and spin
rotations. The condensed matter vacua (ground states) suggest two possible
scenarios of the origin of the combined Lorentz symmetry, both are realized in
the superfluid phases of liquid $^3$He: the $^3$He-A scenario and the $^3$He-B
scenario. In these scenarios the gravitational tetrads are considered as the
order parameter of the symmetry breaking in the quantum vacuum. The $^3$He-B
scenarios applied to the Minkowski vacuum leads to the continuous degeneracy of
the Minkowski vacuum with respect to the $O(3,1)$ spin rotations. The symmetry
breaking leads to the corresponding topological objects, which appear due to
the nontrivial topology of the manifold of the degenerate Minkowski vacua, such
as torsion strings. The 4-fold degeneracy of the Minkowski vacuum with respect
to discrete $P$ and $T$ symmetries suggests that the Weyl fermions are
described by four different tetrad fields: the tetrad for the left-handed
fermions, the tetrad for the right-handed fermions, and the tetrads for their
antiparticles. This may lead to the gravity with several metric fields, so that
the parity violation may lead to the breaking of equivalence principle. Finally
we considered the application of the gravitational tetrads for the solution of
the cosmological constant problem.",2011.06466v11
2021-02-08,On the Radiation Reaction Force,"The usual radiation self-force of a point charge is obtained in a
mathematically exact way and it is pointed out to that this does not call forth
that the spacetime motion of a point charge obeys the Lorentz--Abraham--Dirac
equation.",2102.04983v1
2021-01-22,Dispersion forces in the Lifshitz problem,"We present a sequential derivation of the dispersion forces for the Lifshitz
problem, based on the field mode matching technique. The results for the
dispersion force on the base of the energy-momentum tensor and the Lorentz
force are presented as specral integrals in real domaine.",2102.04988v1
2021-02-10,Casimir-Lifshitz forces and plasmons in a structure of two dielectric rods: Green's function method of electrodynamics,"A new model for calculating the Casimir-Lifshitz force per unit length for
two dielectric rods is proposed, based on the Green function method of
classical electrodynamics and the Lorentz model for permittivity.",2102.07618v1
2021-02-23,Orlicz-Lorentz Gauge functional inequalities for some integral operators,"Let $f \in M_+(\mathbb{R}_+)$, the class of nonnegative, Lebesgure-measurable
functions on $\mathbb{R}_+=(0, \infty)$. We deal with integral operators of the
form \[ (T_Kf)(x)=\int_{\mathbb{R}_+}K(x,y)f(y)\, dy, \quad x \in \mathbb{R}_+,
\] with $K \in M_+(\mathbb{R}_+^2)$.",2102.11431v2
2021-04-05,"Spin(11,3), particles and octonions","The fermionic fields of one generation of the Standard Model, including the
Lorentz spinor degrees of freedom, can be identified with components of a
single real 64-dimensional semi-spinor representation S of the group
Spin(11,3). We describe an octonionic model for Spin(11,3) in which the
semi-spinor representation gets identified with S=OxO', where O,O' are the
usual and split octonions respectively. It is then well-known that choosing a
unit imaginary octonion u in Im(O) equips O with a complex structure J.
Similarly, choosing a unit imaginary split octonion u' in Im(O') equips O' with
a complex structure J', except that there are now two inequivalent complex
structures, one parametrised by a choice of a timelike and the other of a
spacelike unit u'. In either case, the identification S=OxO' implies that there
are two natural commuting complex structures J, J' on S. Our main new
observation is that the subgroup of Spin(11,3) that commutes with both J, J' on
S is the direct product Spin(6) x Spin(4) x Spin(1,3) of the Pati-Salam and
Lorentz groups, when u' is chosen to be timelike. The splitting of S into
eigenspaces of J corresponds to splitting into particles and anti-particles.
The splitting of S into eigenspaces of J' corresponds to splitting of Lorentz
Dirac spinors into two different chiralities. We also study the simplest
possible symmetry breaking scenario with the ""Higgs"" field taking values in the
representation that corresponds to 3-forms in R^{11,3}. We show that this Higgs
can be designed to transform as the bi-doublet of the left/right symmetric
extension of the SM, and thus breaks Spin(11,3) down to the product of the SM,
Lorentz and U(1)_{B-L} groups, with the last one remaining unbroken. This
3-form Higgs field also produces the Dirac mass terms for all the particles.",2104.01786v1
2021-04-05,From two species Vlasov-Maxwell-Boltzmann system to magnetohydrodynamics system,"In this work, the magnetohydrodynamics system is formally derived from two
species Vlasov-Maxwell-Boltzmann system. By employing the hypocoercivity of the
linear Boltzmann operator and overcoming the difficulties resulting from the
singular Lorentz term, we first obtain the uniform estimates of solutions with
respect to the Knudsen number and then derive the magnetohydrodynamics system
from the dimensionless Valsov-Maxwell-Boltzmann system.",2104.01843v2
2021-04-25,Predual of weak Orlicz spaces,"In this paper, we consider the predual spaces of weak Orlicz spaces. As an
application, we provide the Fefferman-Stein vector-valued maximal inequality
for the weak Orlicz spaces. In order to prove this statement, we introduced the
Orlicz-Lorentz spaces, and showed the boundedness of the Hardy-Littlewood
maximal operator on these spaces.",2104.12045v1
2021-05-12,On the Electromagnetic Energies and Forces,"The problem of the `infinite energy' of a point charge is well known in
connection with the Lorentz--Abraham--Dirac equation and, more significantly,
in quantum electrodynamics. Though it is not stated usually, this is strongly
related to the old problem of what the electromagnetic energy-momentum tensor
is. Electromagnetic energies and forces will be examined thoroughly from a new
point of view in the framework of Distribution Theory.",2105.06557v1
2021-06-14,On Generating a Lagrangian for Higher Dimensional Gravity,"The Lovelock Lagrangian is for even dimension D obtained from Weil
polynomials on the Lie algebra of the Lorentz group SO(1,D-1). The procedure
for generating it is related to the Weil homomorphism that converts Lie algebra
invariants into cohomology classes.",2106.07508v1
2021-07-07,Rigidity of joinings for time-changes of unipotent flows on quotients of Lorentz groups,"Let $u_{X}^{t}$ be a unipotent flow on $X=SO(n,1)/\Gamma$, $u_{Y}^{t}$ be a
unipotent flow on $Y=G/\Gamma^{\prime}$. Let $\tilde{u}_{X}^{t}$,
$\tilde{u}_{Y}^{t}$ be time-changes of $u_{X}^{t}$, $u_{Y}^{t}$ respectively.
We show the disjointness (in the sense of Furstenberg) between $u_{X}^{t}$ and
$\tilde{u}_{Y}^{t}$ (or $\tilde{u}_{X}^{t}$ and $u_{Y}^{t}$) in certain
situations.
  Our method refines the works of Ratner and extends a recent work of Dong,
Kanigowski and Wei.",2107.03295v1
2021-09-16,LHAASO discovery of highest-energy photons towards new physics,"Ultrahigh-energy photons up to 1.4 peta-electronvolts have been observed by
new cosmic-ray telescope in China -- a hint that Lorentz invariance might break
down at the Planck-scale level.",2109.07794v1
2021-11-28,A simple proof of ill-posedness for incompressible Euler equations in critical Sobolev spaces,"We provide a simple proof that the Cauchy problem for the incompressible
Euler equations in $\mathbb{R}^{d}$ with any $d\ge3$ is ill-posed in critical
Sobolev spaces, extending an earlier work of Bourgain and Li in the case $d =
3$. The ill-posedness is shown for certain critical Lorentz spaces as well.",2111.14078v2
2021-12-10,Galilean invariance without superluminal particles,"Recently Dragan and Ekert [New. J. Phys 22, 033038, 2020] presented arguments
that probabilistic dynamics inherent in the realm of quantum physics is related
to the propagation of superluminal particles. Moreover they argue that
existence of such particles is a natural consequence of the principle of
relativity. We show that the proposed extension of Lorentz transformation can
be interpreted in natural way without invoking superluminal phenomena.",2112.05658v1
2021-12-31,Duality covariant field redefinitions,"We explore the role of the dilaton field on higher derivative supergravity
within the framework of Double Field Theory and use it to fix the Lorentz non
covariant field redefinitions connecting the metric and dilaton fields with the
duality multiplets.",2201.00030v2
2022-01-12,Translation in momentum space and minimal length,"We show that in presence of the Snyder algebra the notion of translation in
momentum space is modified to a formula similar to the relativistic addition of
velocities. These results confirm the strict connection between Snyder algebra
and the Lorentz group.",2201.04709v2
2022-01-17,On Hochschild homology of uniform Roe algebras with coefficients in uniform Roe bimodules,"It was shown recently by M. Lorentz and R. Willett that all bounded
derivations of the uniform Roe algebras of metric spaces of bounded geometry
are inner. Here we calculate the space of outer derivations of the uniform Roe
algebras with coefficients in uniform Roe bimodules related to various metrics
on the two copies of the given space. We also give some results on the higher
Hochschild cohomology with coefficients in uniform Roe bimodules.",2201.06488v1
2022-01-27,On generally covariant mathematical formulation of Feynman integral in Lorentz signature,"It is widely accepted that the Feynman integral is one of the most promising
methodologies for defining a generally covariant formulation of nonperturbative
interacting quantum field theories (QFTs) without a fixed prearranged causal
background. Recent literature suggests that if the spacetime metric is not
fixed, e.g. because it is to be quantized along with the other fields, one may
not be able to avoid considering the Feynman integral in the original Lorentz
signature, without Wick rotation. Several mathematical phenomena are known,
however, which are at some point showstoppers to a mathematically sound
definition of Feynman integral in Lorentz signature. The Feynman integral
formulation, however, is known to have a differential reformulation, called to
be the master Dyson--Schwinger (MDS) equation for the field correlators. In
this paper it is shown that a particular presentation of the MDS equation can
be cast into a mathematically rigorously defined form: the involved function
spaces and operators can be strictly defined and their properties can be
established. Therefore, MDS equation can serve as a substitute for the Feynman
integral, in a mathematically sound formulation of constructive QFT, in
arbitrary signature, without a fixed background causal structure. It is also
shown that even in such a generally covariant setting, there is a canonical way
to define the Wilsonian regularization of the MDS equation. The main result of
the paper is a necessary and sufficient condition for the regularized MDS
solution space to be nonempty, for conformally invariant Lagrangians. This
theorem also provides an iterative approximation algorithm for obtaining
regularized MDS solutions, and is guaranteed to be convergent whenever the
solution space is nonempty. The algorithm could eventually serve as a method
for putting Lorentz signature QFTs onto lattice, in the original metric
signature.",2201.11408v3
2022-03-24,Renormalizable and unitary Lorentz invariant model of quantum gravity,"We analyze the R + R2 model of quantum gravity where terms quadratic in the
curvature tensor are added to the General Relativity action. This model was
recently proved to be a self-consistent quantum theory of gravitation, being
both renormalizable and unitary. The model can be made practically
indistinguishable from General Relativity at astrophysical and cosmological
scales by the proper choice of parameters.",2204.08007v1
2022-05-09,Asymmetric particle-antiparticle Dirac equation: first quantization,"We derive a Dirac-like equation, the asymmetric Dirac equation, where
particles and antiparticles sharing the same wave number have different
energies and momenta. We show that this equation is Lorentz covariant under
proper Lorentz transformations (boosts and spatial rotations) and also
determine the corresponding transformation law for its wave function. We obtain
a formal connection between the asymmetric Dirac equation and the standard
Dirac equation and we show that by properly adjusting the free parameters of
the present wave equation we can make it reproduce the predictions of the usual
Dirac equation. We show that the rest mass of a particle in the theoretical
framework of the asymmetric Dirac equation is a function of a set of four
parameters, which are relativistic invariants under proper Lorentz
transformations. These four parameters are the analog to the mass that appears
in the standard Dirac equation. We prove that in order to guarantee the
covariance of the asymmetric Dirac equation under parity and time reversal
operations (improper Lorentz transformations) as well as under the charge
conjugation operation, these four parameters change sign in exactly the same
way as the four components of a four-vector. The mass, though, being a function
of the square of those parameters remains an invariant. We also extensively
study the free particle plane wave solutions to the asymmetric Dirac equation
and derive its energy, helicity, and spin projection operators as well as
several Gordon's identities. The hydrogen atom is solved in the present context
after applying the minimal coupling prescription to the asymmetric Dirac
equation, which also allows us to appropriately obtain its non-relativistic
limit.",2205.04516v2
2022-05-15,On completeness and dynamics of compact Brinkmann spacetimes,"Brinkmann Lorentz manifolds are those admitting an isotropic parallel vector
field. We prove geodesic completeness of the compact and also compactly
homogeneous Brinkmann spaces. We also prove, partially, that their parallel
vector field generates an equicontinuous flow.",2205.07243v2
2022-05-15,Selected problems in probability theory,"This celebratory article contains a personal and idiosyncratic selection of a
few open problems in discrete probability theory. These include certain well
known questions concerning Lorentz scatterers and self-avoiding walks, and also
some problems of percolation-type. The author hopes the reader will find
something to leaven winter evenings, and perhaps even a project for the longer
term.",2205.07318v1
2022-06-17,Probing the Lorentz Symmetry Violation Using the First Image of Sagittarius A*: Constraints on Standard-Model Extension Coefficients,"Thanks to unparalleled near-horizon images of the shadows of Messier 87*
(M87*) and Sagittarius A* (Sgr A*) delivered by the Event Horizon Telescope
(EHT), two amazing windows opened up to us for the strong-field test of the
gravity theories as well as fundamental physics. Information recently published
from EHT about the Sgr A*'s shadow lets us have a novel possibility of
exploration of Lorentz symmetry violation (LSV) within the Standard-Model
Extension (SME) framework. Despite the agreement between the shadow image of
Sgr A* and the prediction of the general theory of relativity, there is still a
slight difference which is expected to be fixed by taking some fundamental
corrections into account. We bring up the idea that the recent inferred shadow
image of Sgr A* is explicable by a minimal SME-inspired Schwarzschild metric
containing the Lorentz violating (LV) terms obtained from the post-Newtonian
approximation. The LV terms embedded in Schwarzschild metric are dimensionless
spatial coefficients ${\bar s}^{jk}$ associated with the field responsible for
LSV in the gravitational sector of the minimal SME theory. In this way, one can
control Lorentz invariance violation in the allowed sensitivity level of the
first shadow image of Sgr A*. Actually, using the bounds released within
$1\sigma$ uncertainty for the shadow size of Sgr A* and whose fractional
deviation from standard Schwarzschild, we set upper limits for the two
different combinations of spatial diagonal coefficients and the time-time
coefficient of the SME, as well. The best upper bound is at the $10^{-2}$
level, which should be interpreted differently from those constraints
previously extracted from well-known frameworks since unlike standard SME
studies it is not obtained from a Sun-centered celestial frame but comes from
probing the black hole horizon scale.",2206.08601v3
2022-06-28,Investigating Lorentz Violation with the long baseline experiment P2O,"One of the basic propositions of quantum field theory is Lorentz invariance.
The spontaneous breaking of Lorentz symmetry at a high energy scale can be
studied at low energy extensions like the Standard model in a model-independent
way through
  effective field theory (EFT). The present and future Long-baseline neutrino
experiments can give a scope to observe such a Planck-suppressed physics of
Lorentz invariance violation (LIV). A proposed long baseline experiment,
Protvino to ORCA (dubbed ""P2O"") with a baseline of 2595 km, is expected to
provide good sensitivities to unresolved issues, especially neutrino mass
ordering. P2O can offer good statistics even with a moderate beam power and
runtime, owing to the very large ($\sim 6$ Mt) detector volume at KM3NeT/ ORCA.
Here we discuss in detail, how the individual LIV parameters affect neutrino
oscillations at P2O and DUNE baselines at the level of probability and derive
analytical expressions to understand interesting degeneracies and other
features. We estimate $\Delta \chi^{2}$ sensitivities to the LIV parameters,
analyzing their correlations among each other, and also with the standard
oscillation parameters. We calculate these results for P2O alone and also carry
out a combined analysis of P2O with DUNE. We point out crucial features in the
sensitivity contours and explain them qualitatively with the help of the
relevant probability expressions derived here. Finally, we estimate constraints
on the individual LIV parameters at $95\%$ confidence level (C.L.) intervals
stemming from the combined analysis of P2O and DUNE datasets and highlight the
improvement over the existing constraints. We also find out that the additional
degeneracy induced by the LIV parameter $a_{ee}$ around $-22 \times 10^{-23}$
GeV is lifted by the combined analysis at $95\%$ C.L.",2206.14018v2
2022-07-03,Cherenkov radiation in chiral media,"In the framework of Carrol-Field-Jackiw electrodynamics we calculate the
spectral distribution of the Cherenkov radiation (CHR) produced by a charge
moving at constant velocity in a chiral medium. We find zero, one or two
Cherenkov angles according to the relation between the velocity of the particle
and the refraction index of the medium.",2207.01104v1
2022-08-29,A Special Relativistic Liouville Equation Exists,"In a previous paper, the author asked the question ""Does a Special
Relativistic Liouville Equation Exist?'. In this paper, I give an affirmative
answer. In 8N phase space, a Hamiltonian is derived by breaking the
reparametrization symmetry of the single, Lorentz invariant, mathematical time
introduced, which defines the evolution of all phase space variables.",2208.13387v1
2022-10-13,Some quantitative one-sided weighted estimates,"In this paper we provide some quantitative one-sided estimates that recover
the dependences in the classical setting. Among them we provide estimates for
the one-sided maximal function in Lorentz spaces and we show that the
conjugation method for commutators works as well in this setting.",2210.07127v1
2022-10-22,Holmstedt's formula for the $K$-functional: the limit case $θ_0=θ_1$,"We consider $K$-interpolation spaces involving slowly varying functions, and
derive necessary and sufficient conditions for a Holmstedt-type formula to be
held in the limiting case $\theta_0=\theta_1\in\{0,1\}.$ We also study the case
$\theta_0=\theta_1\in (0,1).$ Applications are given to Lorentz-Karamata
spaces, generalized gamma spaces and Besov spaces.",2210.12377v1
2022-12-23,The Twin Paradox Put to Rest,"In this letter, we give a simple and analytical solution to the twin paradox.
It relies just on Lorentz transformations and does not involve accelerated
frames or any kind of signals exchanged between the twins. We expect that with
this we can put a dead end to this century-old problem.",2212.14811v1
2023-02-09,An Integer Basis for Celestial Amplitudes,"We present a discrete basis of solutions of the massless Klein-Gordon
equation in 3+1 Minkowski space which transform as sl(2,C) Lorentz/conformal
primaries and descendants, and whose elements all have integer conformal
dimension. We show that the basis is complete in the sense that the Wightman
function can be expressed as a quadratic sum over the basis elements.",2302.04905v2
2023-03-19,Astrophysical and Cosmological Searches for Lorentz Invariance Violation,"Lorentz invariance is one of the fundamental tenets of Special Relativity,
and has been extensively tested with laboratory and astrophysical observations.
However, many quantum gravity models and theories beyond the Standard Model of
Particle Physics predict a violation of Lorentz invariance at energies close to
the Planck scale. This article reviews observational and experimental tests of
Lorentz invariance violation (LIV) with photons, neutrinos and gravitational
waves. Most astrophysical tests of LIV using photons are based on searching for
a correlation of the spectral lag data with redshift and energy. These have
been primarily carried out using compact objects such as pulsars, Active
Galactic Nuclei (AGN), and Gamma-ray bursts (GRB). There have also been some
claims for LIV from some of these spectral lag observations with GRBs, which
however are in conflict with the most stringent limits obtained from other LIV
searches. Searches have also been carried out using polarization measurements
from GRBs and AGNs. For neutrinos, tests have been made using both
astrophysical observations at MeV energies (from SN 1987A) as well as in the
TeV-PeV energy range based on IceCube observations, atmospheric neutrinos, and
long-baseline neutrino oscillation experiments. Cosmological tests of LIV
entail looking for a constancy of the speed of light as a function of redshift
using multiple observational probes, as well as looking for birefringence in
Cosmic Microwave Background observations. This article will review all of these
aforementioned observational tests of LIV, including results which are in
conflict with each other.",2303.10643v3
2023-03-24,Rearrangement-invariant hulls of weighted Lebesgue spaces,"We characterize the rearrangement-invariant hull, with respect to a given
measure $\mu$, of weighted Lebesgue spaces. The solution leads us to first
consider when this space is contained in the sum of $(L^1 + L^\infty)(R, \mu)$
and the final condition is given in terms of embeddings for weighted Lorentz
spaces.",2303.13990v1
2023-06-15,Cuspidal crosscaps and folded singularities on a maxface and a minface,"For a given zero mean curvature surface $X$ (in the Lorentz Minkowski space)
having folded singularity, we construct a family of maxface and minface, having
increasing cuspidal crosscaps, converging to $X$. We include a general
discussion of this.",2306.09241v1
2023-07-11,A unified approach to inequalities for K-functionals and moduli of smoothness,"The paper provides a detailed study of crucial inequalities for smoothness
and interpolation characteristics in rearrangement invariant Banach function
spaces. We present a unified approach based on Holmstedt formulas to obtain
these estimates. As examples, we derive new inequalities for moduli of
smoothness and K-functionals in various Lorentz spaces.",2307.05124v2
2023-08-07,On global attraction to solitons for 3D Maxwell-Lorentz equations,"We consider the Maxwell field coupled to a single rotating charge. This
Hamiltonian system admits soliton-type solutions, where the field is static,
while the charge rotates with constant angular velocity. We prove that any
solution of finite energy converges, in suitable local energy seminorms, to the
corresponding soliton in the long time limit.",2308.03611v1
2023-08-04,Superluminal Transformations in Spacetimes of Definite Metric,"This paper reviews and extends an approach to superluminal kinematics set
forth by R. Sutherland and J. Shepanski in 1986. This theory is characterized
by a spacetime with positive definite metric, a Lorentz factor of the form
$1/\sqrt{\beta^2 - 1}$, and real-valued proper times and proper lengths for
superluminal reference frames.",2308.03796v1
2023-08-10,Singular Miminal Ruled Surfaces,"In this paper we study surfaces with minimal potential energy under
gravitational forces, called singular minimal surfaces. We prove that a
singular minimal ruled surface in a Euclidean $3-$space is cylindrical, in
particular as an $\alpha-$catenary cylinder by a result of L\'{o}pez [Ann.
Glob. Anal. Geom. 53(4) (2018), 521-541]. This result is also extended in
Lorentz-Minkowski $3-$space.",2308.05499v1
2023-08-22,"Trace, determinant and eigenvalues of nuclear operators","It is shown how the results in the theory of determinants and traces as well
as in the theory of quasi-normed tensor products can be applied for getting new
theorems on distribution of eigenvalues of nuclear operators in Banach spaces
and on coincidence of spectral and nuclear traces such operators. As examples,
it is considered the new classes of operators -- generalized nuclear operators
of Lorentz--Laprest\'e $N_{(r,s),p}.$",2308.11765v1
2023-09-23,Conservation law of harmonic mappings in supercritical dimensions,"In this short note, we provide a partial extension of Rivi\`ere's
convervation law in higher dimensions under certain Lorentz integrability
condition for the connection matrix. As an application, we obtain a
conservation law for weakly harmonic mappings around regular points in
supercritical dimensions.",2309.13372v1
2023-10-10,Low regularity global well-posedness of axisymmetric MHD equations with vertical dissipation and magnetic diffusion,"Consideration in this paper is the global well-posedness for the 3D
axisymmetric MHD equations with only vertical dissipation and vertical magnetic
diffusion. The existence of unique low-regularity global solutions of the
system with initial data in Lorentz spaces is established by using higher-order
energy estimates and real interpolation method.",2310.06432v1
2023-11-16,Existence and Blow-up for Non-autonomous Scalar Conservation Laws With Viscosity,"We consider a question posed in [GSZZ22], namely the blow-up of the PDE $$u_t
+ (b(t,x) u^{1+k})_x = u_{xx}$$ when $b$ is uniformly bounded, Lipschitz and $k
= 2$. We give a complete answer to the behavior of solutions when $b$ belongs
to the Lorentz spaces $b \in L^{p,\infty}$, $p \in (2,\infty]$, or $b_x \in
L^{p,\infty}$, $p \in (1,\infty]$.",2311.09982v1
2023-12-22,Soft Theorems in Matrix Theory,"We show that the Banks-Fischler-Shenker-Susskind matrix model for M-theory
obeys the leading and subleading soft theorems expected from eleven-dimensional
supergravity. The subleading soft theorem implies the amplitude is Lorentz
symmetric. This is argued for general four point amplitudes, but only for
restricted kinematics for five and higher point amplitudes.",2312.15111v1
2024-01-27,Conservation law for a fourth order elliptic system in supercritical dimensions,"In this short note, we extend the conservation law of Lamm-Rivi\`ere [Comm.
PDEs 2008] for a fourth order elliptic system to supercritical dimensions,
under certain Lorentz-Sobolev integrability assumptions on the associated
coefficient functions.",2401.15401v1
2024-01-28,New physics model constraints derived from SME coefficient limits using IceCube astrophysical neutrino flavour data,"The IceCube collaboration has set stringent limits on neutrino sector
isotropic SME coefficients through the measurement of the astrophysical
neutrino flavor data. We investigate the consequences of these limits on
various new physics models.",2401.15716v1
2024-02-08,A duality between Lorentzian Twisted Spectral Triples and Spectral Triples,"We present a duality between spectral triple and a Lorentzian version of
twisted spectral triples, offering an original approach to Lorentzian geometry
within the context of noncommutative geometry. This duality is used to define a
spectral triple for which the fermionic action is Lorentz invariant, providing
a new candidate for the almost-commutative manifold's spectral triple of the
noncommutative standard model of particles physics.",2402.05839v1
2024-03-13,PMCV hypersurfaces in non-flat pseudo-Riemannian space forms,"In this paper, we prove that PMCV (i.e. \Delta\vec{H} is proportional to
\vec{H}) hypersurface M^n_r of a non-flat pseudo-Riemannian space form
N^{n+1}_s(c) with at most two distinct principal curvatures is minimal or
locally isoparametric, and compute the mean curvature for the isoparametric
ones. As an application, we give full classification results of such
non-minimal Lorentzian hypersurfaces of non-flat Lorentz space forms.",2403.08205v1
2024-03-13,Electron scattering on $^4$He from coupled-cluster theory,"We present a coupled-cluster calculation for the electron-$^4$He scattering
in the region of the quasi-elastic peak. We show the longitudinal and
transverse responses separately, and discuss results within two distinct
theoretical methods: the Lorentz integral transform and spectral functions. The
comparison between them allows to investigate the role of final state
interactions, two-body currents and relativistic effects.",2403.08413v1
2024-02-17,Rotational hypersufaces in $E^4_1$ with generalized $L_k$ 1-type Gauss map,"In this paper, we study the Gauss map of rotational hypersurfaces in
4-dimensional Lorentz-Minkowski space concerning the linear second order
differential operators $L_1$ and $L_2$, where $L_1$ is usually called as the
Cheng-Yau operator. We obtain some classifications of rotational hypersurfaces
which have $L_k$-harmonic Gauss map, $L_k$-pointwise 1-type Gauss map and
generalized $L_k$ 1-type Gauss map, where $k = 1,2$.",2403.19671v1
2024-03-31,Existence for noncoercive nonlinear elliptic equations with two lower-order terms,"This paper considers a class of noncoercive nonlinear elliptic problems with
coefficients defined in Marcinkiewicz and Lorentz spaces. We prove the
existence of a solution for the corresponding Dirichlet problem and investigate
the higher integrability properties of the solution.",2404.00799v1
1994-10-06,Damped Lyman Alpha Systems vs. Cold + Hot Dark Matter,"Damped Ly$\alpha$ systems provide possibly the most significant evidence for
early structure formation, and thus a stringent constraint on the Cold + Hot
Dark Matter (CHDM) cosmology. Using the numbers of halos in N-body simulations
to normalize Press-Schechter (PS) estimates of the number densities of
protogalaxies as a function of redshift, we find that CHDM with
$\Omega_c/\Omega_\nu/\Omega_b = 0.6/0.3/0.1$ is compatible with the damped
Ly$\alpha$ data only at $z<2.5$, but that it is probably incompatible with data
at $z>3$. The predictions of CHDM are quite sensitive to the neutrino fraction.
We find that $\Omega_c/\Omega_\nu/\Omega_b = 0.725/0.20/0.075$ is compatible
with the $z>3$ data. With one massive neutrino species, this corresponds to
lowering the neutrino mass from 7.0 to 4.7 eV, for $H_0=50\kmsMpc$ and
$T=2.726$ K. By analysing our numerical simulations with different resolutions
and box sizes as well as those of Ma \& Bertchinger (1994), we show that for
the CHDM models with $\Omega_\nu$=0.2--0.3 the PS approximation should be used
with Gaussian filter with $\delta_c=1.3-1.4$ if one tries to recover the total
mass of a collapsed halo and to include nonlinear effects, due to waves both
longer and shorter than those within the simulation box.",9410022v1
1995-12-05,Small Scale Structure and High Redshift HI,"Cosmological simulations with gas dynamics suggest that the Lyman-alpha
forest is produced mainly by ""small scale structure"" --- filaments and sheets
that are the high redshift analog of today's galaxy superclusters. There is no
sharp distinction between Lyman-alpha clouds and ""Gunn-Peterson"" absorption
produced by the fluctuating IGM -- the Lyman-alpha forest {\it is} the
Gunn-Peterson effect. Lyman limit and damped Lyman-alpha absorption arises in
the radiatively cooled gas of forming galaxies. At $z~2-3$, most of the gas is
in the photoionized, diffuse medium associated with the Lyman-alpha forest, but
most of the {\it neutral} gas is in damped Lyman-alpha systems. We discuss
generic evolution of cosmic gas in a hierarchical scenario of structure
formation, with particular attention to the prospects for detecting 21cm
emission from high redshift HI. A scaling argument based on the present-day
cluster mass function suggests that objects with $M_{HI} >~ 5e11 h^{-1} \msun$
should be extremely rare at $z~3$, so detections with existing instruments will
be difficult. An instrument like the proposed Square Kilometer Array could
detect individual damped Lyman-alpha systems at high redshift, making it
possible to map structure in the high redshift universe in much the same way
that today's galaxy redshift surveys map the local large scale structure.",9512016v1
1996-04-03,APM z>4 QSO Survey: Spectra and Intervening Absorption Systems,"The APM multicolor survey for bright z > 4 objects, covering 2500 deg^2 of
sky to m(R)~19, resulted in the discovery of thirty-one quasars with z > 4.
High signal-to-noise optical spectrophotometry at 5A resolution has been
obtained for the twenty-eight quasars easily accessible from the northern
hemisphere. These spectra have been surveyed to create new samples of high
redshift Lyman-limit systems, damped Lyman-alpha absorbers, and metal
absorption systems (e.g. CIV and MgII). In this paper we present the spectra,
together with line lists of the detected absorption systems. The QSOs display a
wide variety of emission and absorption line characteristics, with 5 exhibiting
broad absorption lines and one with extremely strong emission lines
(BR2248-1242). Eleven candidate damped Ly-alpha absorption systems have been
identified covering the redshift range 2.8<z<4.4 (8 with z>3.5). An analysis of
the measured redshifts of the high ionization emission lines with the low
ionization lines shows them to be blueshifted by 430+/-60 km/s. In a previous
paper (Storrie-Lombardi et. al. 1994) we discussed the redshift evolution of
the Lyman limit systems catalogued here. In subsequent papers we will discuss
the properties of the Ly-alpha forest absorbers and the redshift and column
density evolution of the damped Ly-alpha absorbers.",9604021v1
1996-04-10,A Keck HIRES Investigation of the Metal Abundances and Kinematics of the z=2.46 Damped Lya System Toward Q0201+365,"We present high resolution ($\approx 8$ \kms) spectra of the QSO Q0201+365
obtained with HIRES, the echelle spectrograph on the 10m W.M. Keck Telescope.
Although we identify over $80\%$ of the absorption features and analyze several
of the more complex metal-line systems, we focus our analysis on the damped
\Lya system at $z=2.462$. Ionization simulations suggest the hydrogen in this
system is significantly neutral and all of the observed metals are
predominantly singly ionized. We measure accurate abundances for Fe, Cr, Si, Ni
and place a lower limit on the abundance of Zn: [Fe/H] = $-0.830 \pm 0.051$,
[Cr/H] = $-0.902 \pm 0.064$, [Si/H] = $-0.376 \pm 0.052$, [Ni/H] = $-1.002 \pm
0.054$ and [Zn/H] $> -0.562 \pm 0.064$. We give evidence suggesting the actual
Zn abundance is [Zn/H] $\approx -0.262$, implying the highest metallicity
observed at a redshift $z \geq 2$. The relative abundances of these elements
remains constant over essentially the entire system ($\approx 150$ \kms in
velocity space), suggesting it is well mixed. Furthermore, we use the lack of
abundance variations to infer properties of the dust responsible for element
depletion. Finally, we discuss the kinematic characteristics of this damped
\Lya system, comparing and contrasting it with other systems. The low-ion line
profiles span $\approx 200$ \kms in velocity space and have an asymmetric shape
with the strongest feature on the red edge. These kinematic characteristics are
consistent with a rotating disk model.",9604042v1
1996-06-13,Damping of Cosmic Magnetic Fields,"We examine the evolution of magnetic fields in an expanding fluid composed of
matter and radiation with particular interest in the evolution of cosmic
magnetic fields. We derive the propagation velocities and damping rates for
relativistic and non-relativistic fast and slow magnetosonic, and Alfv\'en
waves in the presence of viscous and heat conducting processes. The analysis
covers all MHD modes in the radiation diffusion and the free-streaming regimes.
When our results are applied to the evolution of magnetic fields in the early
universe, we find that cosmic magnetic fields are damped from prior to the
epoch of neutrino decoupling up to recombination. Our findings have multifold
implications for cosmology. The dissipation of magnetic field energy into heat
during the epoch of neutrino decoupling ensures that most magnetic field
configurations generated in the very early universe satisfy big bang
nucleosynthesis constraints. Further dissipation before recombination
constrains models in which primordial magnetic fields give rise to galactic
magnetic fields or density perturbations. Finally, the survival of Alfv\'en and
slow magnetosonic modes on scales well below the Silk mass may be of
significance for the formation of structure on small scales (abridged).",9606080v2
1997-01-09,Molecular Hydrogen Absorption in the z= 1.97 Damped Lyman alpha Absorption system toward QSO 0013-004,"We present a new ultra-violet spectrum of the QSO 0013-004 with 0.9 \AA
resolution obtained with the MMT Blue spectrograph. The \upsilon = 0 - 0, 1 -
0, 2 - 0 and 3 - 0 Lyman bands of H_2 associated with the z = 1.9731 damped Ly
alpah absorption line system have been detected. The H_2 column density is
N(H_2) = 6.9 (\pm 1.6)\times 10^{19} cm^{-2}, and the Doppler parameter b =
15\pm 2 km/s. The populations of different rotational levels are measured and
used to derive the excitation temperatures. The estimated kinetic temperature
T_K\sim 70 K, and the total particle number density n(H) \sim 300 cm^{-3}. The
UV photoabsorption rate $\beta_0 \sim 6.7\times 10^{-9}$ s^{-1}, about a factor
of few times greater than that in a typical diffuse Milky Way interstellar
cloud. The total hydrogen column density is $N(H) = 6.4(\pm 0.5)\times 10^{20}
cm^{-2}$. The fractional H_2 abundance f = 2N(H_2)/(2N(H_2) + N(H I)) \sim 0.22
\pm 0.05 is the highest among all observed damped Ly\al absorbers. The high
fractional H_2 abundance is consistent with the inferred presence of dust and
strong C I absorption in this absorber.",9701041v1
1997-02-06,Abundance Patterns of Heavy Elements in Damped Lyman-Alpha Galaxies,"We present a quantitative analysis of the abundances of heavy elements in
damped Ly-alpha galaxies in the sample of Lu et al. (1996). In particular, we
compare the observed gas-phase abundances with those expected when the
intrinsic (i.e., nucleosynthetic) pattern is the same as that in either the Sun
or in Galactic halo stars and when the depletion pattern is the same as that in
the warm Galactic interstellar medium, but with various values of the
dust-to-metals ratio. We find that the observations are equally consistent with
the solar and halo-star intrinsic patterns and that they favor some depletion,
the typical dust-to-metals ratio being 40%-90% of that in the Milky Way today.
However, neither intrinsic pattern matches the observations perfectly. For the
solar pattern, the discrepancy is mainly with [Mn/Fe], while for the halo-star
pattern, the discrepancy is with [Zn/Fe], [Ni/Fe], and possibly [Al/Fe]. Our
analysis does not support the claim by Lu et al. that the damped Ly-alpha
galaxies have halo-star abundance patterns and no dust depletion.",9702066v2
1997-07-15,"Linear Response, Dynamical Friction and the Fluctuation-Dissipation Theorem in Stellar Dynamics","We apply linear response theory to a general, inhomogeneous, stationary
stellar system, with particular emphasis on dissipative processes analogous to
Landau damping. Assuming only that the response is causal, we show that the
irreversible work done by an external perturber is described by the
anti-Hermitian part of a linear response operator, and damping of collective
modes is described by the anti-Hermitian part of a related polarization
operator. We derive an exact formal expression for the response operator, which
is the classical analog of a well-known result in quantum statistical physics.
When the self-gravity of the response can be ignored, and the ensemble-averaged
gravitational potential is integrable, the expressions for the mode energy,
damping rate, and polarization operator reduce to well-known formulae derived
from perturbation theory in action-angle variables. In this approximation,
dissipation occurs only via resonant interaction with stellar orbits or
collective modes. For stellar systems in thermal equilibrium, the
anti-Hermitian part of the response operator is directly related to the
correlation function of the fluctuations. Thus dissipative properties of the
system are completely determined by the spectrum of density fluctuations---the
fluctuation-dissipation theorem. In particular, we express the coefficient of
dynamical friction for an orbiting test particle in terms of the fluctuation
spectrum; this reduces to the known Chandrasekhar formula in the restrictive
case of an infinite homogeneous system with a Maxwellian velocity distribution.",9707161v1
1997-08-04,"Violent Relaxation, Phase Mixing, and Gravitational Landau Damping","This paper proposes a geometric interpretation of flows generated by the
collisionless Boltzmann equation (CBE), focusing on the coarse-grained approach
towards equilibrium. The CBE is a noncanonical Hamiltonian system with the
distribution function f the fundamental dynamical variable, the mean field
energy H[f] playing the role of the Hamiltonian and the natural arena of
physics being the infinite-dimensional phase space of distribution functions.
Every time-independent equilibrium f_0 is an energy extremal with respect to
all perturbations that preserve the constraints associated with Liouville's
Theorem, local energy minima corresponding to linearly stable equilibria. If an
initial f(t=0) is sufficiently close to some linearly stable lower energy f_0,
its evolution involves linear phase space oscillations about f_0 which, in many
cases, would be expected to exhibit linear Landau damping. If f(t=0) is far
from any stable extremal, the flow will be more complicated but, in general,
one would anticipate that the evolution involves nonlinear oscillations about
some lower energy f_0. In this picture, the coarse-grained approach towards
equilibrium usually termed violent relaxation is interpreted as nonlinear
Landau damping. The evolution of a generic initial f(t=0) involves a coherent
initial excitation, not necessarily small, being converted into incoherent
motion associated with nonlinear oscillations about some equilibrium f_0 which,
in general, will exhibit destructive interference.",9708026v1
1998-11-23,The Physical Nature of the Lyman Limit Systems,"We analyze Keck HIRES observations of a Lyman limit system at z=2.652 toward
Q2231-00. These observations afford the most comprehensive study of the
physical properties of a LL system to date. By comparing the ionic column
densities for Fe^+, Fe^{++}, Si^+, and Si^{3+} against calculations derived
from the CLOUDY software package, we have strictly constrained the ionization
state of this system. This has enabled us to calculate accurate abundances of a
Lyman limit system for the first time at z > 2, e.g., [Fe/H] = -0.5 \pm 0.1. We
also derive a total hydrogen column density, log N(H) = 20.73 \pm 0.2, which is
comparable to values observed for the damped lya systems.
  The system is special for exhibiting CII* 1335 absorption, allowing an
estimate of the electron density, n_e = 6.5 \pm 1.3 x 10^{-2} cm^{-3}. Coupling
this measurement with our knowledge of the ionization state, we derive the
following physical properties: (1) hydrogen volume density, n_H = 5.9 \pm 1.2 x
10^{-2} cm^{-3}, (2) path length, l = 3 \pm 1.6 kpc, and (3) ionizing
intensity, log J_{912} = -20.22 \pm 0.21. We point out that a number of the
physical properties (e.g. [Fe/H], N(H), n_H) resemble those observed for the
damped lya systems, which suggests this system may be the photoionized analog
of a damped system. The techniques introduced in this Letter should be
applicable to a number of Lyman limit systems and therefore enable a survey of
their chemical abundances and other physical properties.",9811357v1
1998-12-03,Gravity-Modes in ZZ Ceti Stars III. Eigenvalues and Eigenfuctions,"We report on numerical calculations of nonadiabatic eigenvalues and
eigenfunctions for g-modes in ZZ Ceti variables. The spectrum of overstable
$l=1$ modes delineates the instability strip. Its blue edge occurs where
$\omega \tau_c \approx 1$ for the $n=1$ mode. Here $\omega$ is radian frequency
and $\tau_c$ is about four times the thermal timescale at the bottom of the
surface convection zone. As a ZZ Ceti cools, its convection zone deepens,
longer period modes become overstable, but the critical value of $\omega\tau_c$
separating overstable and damped modes rises. The latter is a consequence of
enhanced radiative damping for modes which propagate immediately below the
convection zone. The critical value of $\omega\tau_c$ is of observational
significance because modes with the smallest value of $\omega\tau_c$ are most
observable photometrically. Maximum periods for overstable modes predicted for
our cooler model envelopes are about a factor two longer than the observational
upper limit of $1,200\s$. We assess a number of plausible resolutions for this
discrepancy among which convective overshoot and nonlinear saturation look
promising. The nonadiabatic eigenfunctions enable us to predict relative
amplitudes and phases of photospheric variations of flux and velocity,
quantities made accessible by recent observations. We also present asymptotic
formula for damping rates of high order modes, a result of consequence for
future investigations of nonlinear saturation of the amplidues of overstable
modes.",9812085v1
1999-01-19,"Collisionless Dissipative Nonlinear Alfven Waves: Nonlinear Steepening, Compressible Turbulence, and Particle Trapping","The magnetic energy of nonlinear Alfven waves in compressible plasmas may be
ponderomotively coupled only to ion-acoustic quasi-modes which modulate the
wave phase velocity and cause wave-front steepening. In the collisionless
plasma with $\beta\not=0$, the dynamics of nonlinear Alfven wave is also
affected by the resonant particle-wave interactions. Upon relatively rapid
evolution (compared to the particle bounce time), the quasi-stationary wave
structures, identical to the so called (Alfvenic) Rotational Discontinuities,
form, the emergence and dynamics of which has not been previously understood.
Collisionless (Landau) dissipation of nonlinear Alfven waves is also a
plausible and natural mechanism of the solar wind heating. Considering a
strong, compressible, Alfvenic turbulence as an ensemble of randomly
interacting Alfvenic discontinuities and nonlinear waves, it is shown that
there exist two distinct phases of turbulence. What phase realizes depends on
whether this collisionless damping is strong enough to provide adequate energy
sink at all scales and, thus, to support a steady-state cascade of the wave
energy. In long-time asymptotics, however, the particle distribution function
is affected by the wave magnetic fields. In this regime of nonlinear Landau
damping, resonant particles are trapped in the quasi-stationary Alfvenic
discontinuities, giving rise to a formation of a plateau on the distribution
function and quenching collisionless damping. Using the virial theorem for
trapped particles, it is analytically demonstrated that their effect on the
nonlinear dynamics of such discontinuities is non-trivial and forces a
significant departure of the theory from the conventional paradigm.",9901257v1
2000-06-06,A Model of Metallicity Evolution in the Early Universe,"We apply the phenomenological model used to explain the abundances of Fe and
r-process elements in very metal-poor stars in the Galaxy to [Fe/H] of damped
Ly alpha systems. It is assumed that the first stars formed after the Big Bang
were very massive and promptly enriched the interstellar medium to [Fe/H] ~ -3,
at which metallicity formation of normal stars took over. Subsequent Fe
enrichment was provided by Type II supernovae. The range of [Fe/H] at a given
redshift z for damped Ly alpha systems is explained by the time t* after the
Big Bang at which normal star formation started in an individual protogalactic
system. The average t* is approx 80% the age of the universe for damped Ly
alpha systems at z approx 1.5 to 4.5, indicating a long delay between the Big
Bang and the turn-on of protogalaxies. It is inferred that a substantial
fraction of the total baryonic matter may not have been aggregated into
protogalaxies where normal star formation had occurred down to z ~ 1.5. The
data near z = 2.2 suggest that the rate of turn-on of protogalaxies was
initially very low and slowly reached a maximum at ~ 3 Gyr after the Big Bang.
This may be important in understanding the rate of formation of quasars.",0006082v2
2000-09-27,Lensing properties of 7 damped Lyman-alpha absorbing galaxy-QSO pairs,"Le Brun et al. (1997) presented the first identifications of the galaxies
giving rise to 7 intermediate redshift damped Ly-alpha (DLA) absorption
systems. Here, we study the gravitational lensing properties of these
foreground galaxies based on their observed optical appearance and on the
absence of any secondary lensed quasar image. We consider the possibility that
any secondary image be hidden due to extinction by dust, but find it unlikely.
We derive upper limits on the amplification factor affecting the luminosity of
the background quasars; in each case, this factor is found to be less than 0.3
mag. We also obtain upper limits on the total mass of the damped Ly-alpha
galaxies, within radii equal to the quasar impact parameters. Mass-to-light
ratios are found to be consistent with existing estimates based on X-ray
emission or on motion of dwarf satellites. Although we show that lensing is not
important in this sample, we note that existing DLA surveys used to determine
the cosmological density of gas at z<1 are based on samples of quasars brighter
than the ones considered here and for which the amplification bias is likely to
be stronger.",0009433v1
2000-11-14,Sharp HI edges at high z: the gas distribution from Damped Lyman-alpha to Lyman-limit absorption systems,"We derive the distribution of neutral and ionized gas in high redshift clouds
which are optically thick to hydrogen ionizing radiation, using published data
on Lyman-limit and Damped Lyman-alpha absorption systems in the redshift range
1.75 < z < 3.25. We assume that the distribution of the hydrogen total (HI+HII)
column density in the absorbers follows a power law K N_H^{-alpha}, whereas the
observed HI column density distribution deviates from a pure power law as a
result of ionization from a background radiation field. Comparison of the
models and observations give Maximum Likelihood solutions for the exponent
alpha and for X, the value of log(N_H/N_HI) when the Lyman-limit optical depth
is unity: alpha=2.7^{+1.0}_{-0.7} and X=2.75\pm0.35. X is much lower than what
would be obtained for a gaseous distribution in equilibrium under its own
gravity but the ratio of dark matter to gas density is not well constrained
being log(eta_0)=1.1\pm 0.8. An extrapolation of our derived power law
distribution towards systems of lower column density, the Lyman-alpha forest,
favours models with log(eta_0) < 1.1 and alpha=2.7-3.3. With alpha appreciably
larger than 2, Lyman-limit systems contain more gas than Damped Lyman-alpha
systems and Lyman-alpha forest clouds even more. Estimates of the cosmological
gas and dark matter density due to absorbers of different column density around
z=2.5 are also given.",0011268v1
2000-11-29,Implications of 21cm observations for damped Ly-$α$ systems,"We present Giant Metrewave Radio Telescope HI 21cm absorption observations,
of candidate and confirmed damped Lyman-$\alpha$ systems (DLAS). The derived
spin temperatures (T_s) are in all cases $\sim 1000$ K or higher. We have also
collated from the literature a list of DLAS for which 21cm observations exist,
and discuss their implications for the nature of the absorbers.
  A cross-comparison of the 21cm profiles with low ionization metal profiles
shows that the 21cm absorption coincides in velocity with the deepest metal
line feature. This is consistent with models in which the deep metal line
features arise from discrete clouds but not with models where the deepest
features are the result of velocity crowding.
  We also find that the typical derived spin temperatures of DLAS are
considerably higher than those in the Galaxy or nearby spirals. The only
exceptions are DLAS which are known to be associated with the disks of spirals;
these do, in fact, show low spin temperatures. In a multi-phase medium,the
derived T_s is a weighted average of the temperatures of the individual phases.
High derived T_s values are hence to be expected from small, low metallicity
objects, since these objects should have a lower fraction of the cold phase in
their ISM as compared to large galaxies. The high T_s in DLAS is hence
consistent with their observed low metallicities as well as with recent
observations that DLAS are also associated with dwarf/LSB galaxies. Finally, we
suggest that the following trend may be identified: at low redshift, damped
absorption arises from a range of systems, including spiral galaxy disks,
while, at high redshift, absorption occurs predominantly in smaller systems.
(Abridged)",0011540v1
2001-01-18,A Comprehensive Statistical Analysis of the Gas Distribution in Lyman-limit and Damped Lyman-alpha Absorption Systems,"In this paper we show how to use data on Lyman-limit and Damped Lyman-alpha
absorption systems to derive the hydrogen ionization fractions and the
distribution of the face-on total gas column density. We consider axially
symmetric, randomly oriented absorbers, ionized by an external background
radiation field in order to relate the face-on total gas distribution to that
of the neutral hydrogen observed along the line of sight. We devise a
statistical procedure based on the Maximum Likelihood criterion, that is able
to treat simultaneously data coming from different surveys and statistically
recovers the ""true"" column densities in the presence of large uncertainties:
this is especially important for Lyman-limit systems which leave an
unmeasurable residual flux at wavelengths shorter than the Lyman break. We make
use of simulated data to look for possible observational biases and extensively
test our procedure. For a large statistical sample of real data in the redshift
range [1.75,3.25] (collected from all published surveys) our Maximum Likelihood
procedure gives a power-law slope for the total hydrogen distribution of -2.7.
All together Lyman-limit systems therefore contain more gas than Damped
Lyman-alpha systems. Analysis of data at other redshifts shows that more
observations are needed to reach a compelling evidence for a cosmological
evolution of the slope of the gas distribution.",0101335v1
2001-04-29,The First Detection of Co in a Damped Lyman Alpha System,"The study of elemental abundances in Damped Lyman Alpha systems (DLAs) at
high redshift represents one of our best opportunities to probe galaxy
formation and chemical evolution at early times. By coupling measurements made
in high z DLAs with our knowledge of abundances determined locally and with
nucleosynthetic models, we can start to piece together the star formation
histories of these galaxies. Here, we discuss the clues to galactic chemical
evolution that may be gleaned from studying the abundance of Co in DLAs. We
present high resolution echelle spectra of two QSOs, Q2206-199 and Q1223+17,
both already known to exhibit intervening damped systems. These observations
have resulted in the first ever detection of Co at high redshift, associated
with the z= 1.92 DLA in the sightline towards Q2206-199. We find that the
abundance of Co is approximately 1/4 solar and that there is a clear
overabundance relative to iron, [Co/Fe] = +0.31 +/- 0.05. From the abundance of
Zn, we determine that this is a relatively metal-rich DLA, with a metallicity
approximately 1/3 solar. Therefore, this first detection of Co is similar to
the marked overabundance relative to Fe seen in Galactic bulge and thick disk
stars.",0104466v1
2001-06-22,Self-Absorption of Ionizing Radiation and Extended Lyman Alpha Emission in High- Redshift QSOs,"We calculate the neutral hydrogen column density of self-absorption in QSOs
predicted in a model where the QSOs are located in the same halos that contain
the gas in damped Lya absorption systems. The model is parameterized by the
probability P_0 that any halo has an active QSO. We assume that the QSOs ionize
the gas, but do not expel or heat it. The derived HI column densities produce
negligible Lyman limit absorption, even in the lowest luminosity QSOs, with an
optical depth of only ~ 10% for luminosity L=0.01 L_*, when P_0=10^{-2}. We
also compute the HeII Lyman limit self-absorption, which is slightly higher but
still negligible. The self-absorption can be higher if the gas is highly
clumped; only in this case the overall emissivity from QSOs could be
significantly reduced due to absorption by the known damped Lya systems, to
affect the predicted intensity of the ionizing background or the epoch of HeII
reionization. The presence of the gas associated with damped absorption systems
around QSOs could also be detected from the narrow Lya emission line, which
should have and angular extent of 0.1 to 1'' in typical high-redshift QSOs.",0106424v2
2001-06-22,Compressible MHD Turbulence in Interstellar Plasmas,"Radio-wave scintillation observations reveal a nearly Kolmogorov spectrum of
density fluctuations in the ionized interstellar medium. Although this density
spectrum is suggestive of turbulence, no theory relevant to its interpretation
exists. We calculate the density spectrum in turbulent magnetized plasmas by
extending the theory of incompressible MHD turbulence given by Goldreich &
Sridhar to include the effects of compressibility and particle transport. Our
most important results are as follows. (1) Density fluctuations are due to the
slow mode and the entropy mode. Both modes are passively mixed by the cascade
of shear Alfven waves. Since the shear Alfven waves have a Kolmogorov spectrum,
so do the density fluctuations. (2) Observed density fluctuation amplitudes
imply either that the magnetic and gas pressures are comparable, or that the
outer scale of the turbulence is very small. (3) A high degree of ionization is
required for the cascade to survive damping by neutrals and thereby to extend
to small lengthscales. Regions that are insufficiently ionized produce density
fluctuations only on lengthscales larger than the neutral damping scale. These
regions may account for the excess of power that is found on large scales. (4)
Both the entropy mode and the slow mode are damped on lengthscales below that
at which protons can diffuse across an eddy during the eddy's turnover time.
Consequently, eddies whose extents along the magnetic field are smaller than
the proton collisional mean free path do not contribute to the density
spectrum. However, in MHD turbulence eddies are highly elongated along the
magnetic field. From an observational perspective, the relevant lengthscale is
that transverse to the magnetic field. Thus the cut-off lengthscale for density
fluctuations is significantly smaller than the proton mean free path.",0106425v1
2001-11-20,Collisional Cascades in Planetesimal Disks I. Stellar Flybys,"We use a new multiannulus planetesimal accretion code to investigate the
evolution of a planetesimal disk following a moderately close encounter with a
passing star. The calculations include fragmentation, gas and
Poynting-Robertson drag, and velocity evolution from dynamical friction and
viscous stirring. We assume that the stellar encounter increases planetesimal
velocities to the shattering velocity, initiating a collisional cascade in the
disk. During the early stages of our calculations, erosive collisions damp
particle velocities and produce substantial amounts of dust. For a wide range
of initial conditions and input parameters, the time evolution of the dust
luminosity follows a simple relation, L_d/L_{\star} = L_0 / [alpha +
(t/t_d)^{beta}]. The maximum dust luminosity L_0 and the damping time t_d
depend on the disk mass, with L_0 proportional to M_d and t_d proportional to
M_d^{-1}. For disks with dust masses of 1% to 100% of the `minimum mass solar
nebula' (1--100 earth masses at 30--150 AU), our calculations yield t_d approx
1--10 Myr, alpha approx 1--2, beta = 1, and dust luminosities similar to the
range observed in known `debris disk' systems, L_0 approx 10^{-3} to 10^{-5}.
Less massive disks produce smaller dust luminosities and damp on longer
timescales. Because encounters with field stars are rare, these results imply
that moderately close stellar flybys cannot explain collisional cascades in
debris disk systems with stellar ages of 100 Myr or longer.",0111384v1
2002-02-11,The Contribution of HI-rich Galaxies to the Damped Lyman-alpha Absorber Population at z=0,"We present a study of the expected properties of the low redshift damped
Lyman-alpha absorber population determined from a sample of HI-selected
galaxies in the local universe. Because of a tight correlation between the HI
mass and HI cross-section, which we demonstrate spans all galaxy types, we can
use our HI-selected sample to predict the properties of the absorption line
systems. We use measurements of the number density and HI cross-section of
galaxies to show that the total HI cross-section at column densities sufficient
to produce damped Lyman-alpha absorption is consistent with no evolution of the
absorber population. We also find that the dN/dz distribution is dominated by
galaxies with HI masses near 10^9 Msolar. However, because of the large
dispersion in the correlation between HI mass and stellar luminosity, we find
that the distribution of dN/dz as a function of L_J is fairly flat.
Additionally, we examine the line widths of the HI-selected galaxies and show
that there may be evolution in the kinematics of HI-rich galaxies, but it is
not necessary for the higher redshift population to contain a greater
proportion of high mass galaxies than we find locally.",0202216v2
2002-03-18,Monte Carlo Simulation of Lyman Alpha Scattering and Application to Damped Lyman Alpha Systems,"A Monte Carlo code to solve the transfer of Lyman alpha (Lya) photons is
developed, which can predict the Lya image and two-dimensional Lya spectra of a
hydrogen cloud with any given geometry, Lya emissivity, neutral hydrogen
density distribution, and bulk velocity field. We apply the code to several
simple cases of a uniform cloud to show how the Lya image and emitted line
spectrum are affected by the column density, internal velocity gradients, and
emissivity distribution. We then apply the code to two models for damped Lya
absorption systems: a spherical, static, isothermal cloud, and a flattened,
axially symmetric, rotating cloud. If the emission is due to fluorescence of
the external background radiation, the Lya image should have a core
corresponding to the region where hydrogen is self-shielded. The emission line
profile has the characteristic double peak with a deep central trough. We show
how rotation of the cloud causes the two peaks to shift in wavelength as the
slit is perpendicular to the rotation axis, and how the relative amplitude of
the two peaks is changed. In reality, damped Lya systems are likely to have a
clumpy gas distribution with turbulent velocity fields, which should smooth the
line emission profile, but should still leave the rotation signature of the
wavelength shift across the system.",0203287v2
2002-04-09,The Non-Damped Nature of Twelve Low-Redshift Damped Lyman Alpha Candidate Systems,"Hubble Space Telescope (HST) UV spectroscopy of 12 candidate low-redshift
damped Lyman alpha (DLA) systems in 11 QSOs (z=0.103 in Q0054+144, z=0.969 and
z=0.987 in Q0302-223, z=0.478 in Q0454-220, z=1.476 in Q1047+550, z=1.070 in
Q1206+459, z=1.228 in Q1247+267, z=0.399 in Q1318+290B, z=0.519 in Q1329+412,
z=0.276 in Q1451-375, z=0.204 in Q2112+059, z=0.263 in Q2251+113) are
presented; the observations demonstrate that they are not DLAs with
$N(HI)\ge2\times10^{20}$ atoms cm$^{-2}$. In all cases except two the systems
either do not exist or are well below the DLA threshold column density; the
exceptions are a z=0.474 system in Q0454-220 which has $N(HI)=3\times10^{19}$
atoms cm$^{-2}$ and a z=1.223 system in Q1247+267 which has
$N(HI)=8\times10^{19}$ atoms cm$^{-2}$. Despite the availability of data in the
HST archives demonstrating that these are not suitable targets, many have
unfortunately been approved for observation with Chandra, Gemini, and/or HST
with the intent of doing followup work on low-redshift DLAs. Furthermore, these
results indicate that the low-redshift DLA statistics derived from IUE spectra
and presented by Lanzetta, Wolfe, & Turnshek (1995) and Wolfe et al. (1995) are
invalid.",0204155v1
2002-05-17,High matter density peaks from UVES observations of QSO pairs: correlation properties and chemical abundances,"We study the transverse clustering properties of high matter density peaks as
traced by high column density absorption systems (either Lyman limit systems
characterized by N(HI)> 2 x 10^{17} cm^{-2} or CIV systems with W_{r}> 0.5 A)
at redshifts between 2 and 3 with UVES spectra of two QSO pairs (UM680/UM681 at
56 arcsec angular separation and Q2344+1228/Q2343+1232 at 5 arcmin angular
separation) and a QSO triplet (Q2139-4433/Q2139-4434/Q2138-4427 at 1, 7 and 8
arcmin angular separation). We find 3 damped Ly-alpha systems (N(HI)> 2 x
10^{20} cm^{-2}): 2 coinciding with strong metal systems in the nearby line of
sight and 1 matching the emission redshift of the paired QSO; plus 7 Lyman
limit systems: 4 forming two matching couples and 3 without a corresponding
metal system within ~3000 km/s in the coupled line of sight. In summary, we
detect five out of ten matching systems within 1000 km/s, indicating a highly
significant overdensity of strong absorption systems over separation lengths
from ~1 to 8 h^{-1} Mpc. The observed coincidences could arise in gas due to
starburst-driven superwinds associated with a quasar or a galaxy, or gas
belonging to large scale structures like filaments or sheets. We also determine
chemical abundance ratios for three damped Ly-alpha systems. In particular, for
the damped system at z ~ 2.53788 in the spectrum of Q2344+1228, new estimates
of the ratios O/Fe, C/Fe are obtained: [C/Fe]<0.06, [O/Fe]<0.2. They indicate
that O and C are not over-solar in this system.",0205299v1
2002-08-28,Complex rotation with internal dissipation. Applications to cosmic-dust alignment and to wobbling comets and asteroids,"Neutron stars, asteroids, comets, cosmic-dust granules, spacecraft, as well
as whatever other freely spinning body dissipate energy when they rotate about
any axis different from principal. We discuss the internal-dissipation-caused
relaxation of a freely precessing rotator towards its minimal-energy mode (mode
that corresponds to the spin about the maximal-inertia axis). While the body
nutates at some rate, the internal stresses and strains within the body
oscillate at frequencies both higher and lower than this rate. The internal
dissipation takes place mostly the second and higher harmonics. We discuss the
application of our findings to asteroids. Regarding the comets, estimates show
that the currently available angular resolution of spacecraft-based instruments
makes it possible to observe wobble damping within year- or maybe even
month-long spans of time. We also discuss cosmic-dust astrophysics; in
particular, the role played by precession damping in the dust alignment. We
show that this damping provides coupling of the grain's rotational and
vibrational degrees of freedom; this entails occasional flipping of dust grains
due to thermal fluctuations. During such a flip, grain preserves its angular
momentum, but the direction of torques arising from H2 formation reverses. As a
result, flipping grain will not rotate fast in spite of the action of
uncompensated H2 formation torques. The grains get ``thermally trapped,'' and
their alignment is marginal.",0208489v1
2003-06-16,Damping of Tensor Modes in Cosmology,"An analytic formula is given for the traceless transverse part of the
anisotropic stress tensor due to free streaming neutrinos, and used to derive
an integro-differential equation for the propagation of cosmological
gravitational waves. The solution shows that anisotropic stress reduces the
squared amplitude by 35.6 % for wavelengths that enter the horizon during the
radiation-dominated phase, independent of any cosmological parameters. This
decreases the tensor temperature and polarization correlation functions for
these wavelengths by the same amount. The effect is less for wavelengths that
enter the horizon at later times. At the longest wavelengths the decrease in
the tensor correlation functions due to neutrino free streaming ranges from
10.7% for $\Omega_Mh^2=0.1$ to 9.0% for $\Omega_Mh^2=0.15$. An Appendix gives a
general proof that tensor as well as scalar modes satisfy a conservation law
for perturbations outside the horizon, even when the anisotropic stress tensor
is not negligible.",0306304v2
2003-12-30,Nonlinear Pulsations in Differentially Rotating Neutron Stars: Mass-Shedding-Induced Damping and Splitting of the Fundamental Mode,"We study small-amplitude, nonlinear pulsations of uniformly and
differentially rotating neutron stars employing a two-dimensional evolution
code for general-relativistic hydrodynamics. Using Fourier transforms at
several points inside the star, both the eigenfrequencies and two-dimensional
eigenfunctions of pulsations are extracted. The centrifugal forces and the
degree of differential rotation have significant effects on the
mode-eigenfunction. We find that near the mass-shedding limit, the pulsations
are damped due to shocks forming at the surface of the star. This new damping
mechanism may set a small saturation amplitude for modes that are unstable to
the emission of gravitational waves. After correcting for the assumption of the
Cowling approximation (used in our numerical code), we construct empirical
relations that predict the range of gravitational-wave frequencies from
quasi-periodic post-bounce oscillations in the core collapse of massive stars.
We also find that the fundamental quasi-radial mode is split, at least in the
Cowling approximation and mainly in differentially rotating stars, into two
different sequences.",0312648v2
2004-01-16,Simulating stochastically excited oscillations. The mode lifetime of xi Hya,"The discovery of solar-like oscillations in the giant star xy Hya (G7III) was
reported by Frandsen et al. (2002). Their frequency analysis was very limited
due to alias problems in the data set (caused by single-site observations). The
extent to which the aliasing affected their analysis was unclear due to the
unknown damping time of the stellar oscillation modes. In this paper we
describe a simulator created to generate time series of stochastically excited
oscillations, which takes as input an arbitrary window function and includes
both white and non-white noise. We also outline a new method to compare a large
number of simulated time series with an observed time series to determine the
damping time, amplitude, and limited information on the degree of the
stochastically excited modes. For xi Hya we find the most likely amplitude to
be ~ 2 m/s, in good agreement with theory (Houdek & Gough, 2002), and the most
likely damping time to be ~ 2 days, which is much shorter than the theoretical
value of 15-20 days calculated by Houdek & Gough (2002).",0401331v1
2004-10-13,On the Importance of Local Sources of Radiation in Cosmological Absorption Systems,"An upper limit to the importance of local sources of radiation compared to
the cosmic background in cosmological absorption systems is derived, as a
simple consequence of the conservation of surface brightness. The limit depends
only on the rate of incidence of the absorbers and the mean free path of the
radiation. It is found that, on average, the ionizing radiation intensity from
local sources in Lyman limit systems at z>2 must be less than half of the
intensity of the cosmic background. In absorbers with column densities much
lower than Lyman limit systems, the local source contribution must be
negligible. The limit on the ratio of local source to background intensities is
then applied to the class of damped Lya absorption systems with detectable
excited CII lines. A cooling rate of the gas in these systems has been measured
by Wolfe et al., who assumed that the balancing heating source is photoelectric
heating on dust by light at ~ 1500 A . The intensity from local star formation
at this wavelength in this class of damped Lya systems is found to be at most ~
3 times the background intensity. If the heating source is indeed photoelectric
heating of dust, the background created by sources associated with damped Lya
systems can then be estimated from the average cooling rates measured in the
absorbers. Current results yield a background intensity higher than previous
estimates based on observed galaxy and quasar luminosity functions, although
with a large uncertainty. The possibility of other sources of heating, such as
shock-heating in a turbulent medium, should be explored.",0410315v1
2005-04-04,Relativistic r-modes and Shear viscosity: regularizing the continuous spectrum,"Within a fully relativistic framework, we derive and solve numerically the
perturbation equations of relativistic stars, including the stresses produced
by a non-vanishing shear viscosity in the stress-energy tensor. With this
approach, the real and imaginary parts of the frequency of the modes are
consistently obtained. We find that, approaching the inviscid limit from the
finite viscosity case, the continuous spectrum is regularized and we can
calculate the quasi-normal modes for stellar models that do not admit solutions
at first order in perturbation theory when the coupling between the polar and
axial perturbations is neglected. The viscous damping time is found to agree
within factor 2 with the usual estimate obtained by using the eigenfunctions of
the inviscid limit and some approximation for the energy dissipation integrals.
We find that the frequencies and viscous damping times for relativistic
$r-$modes lie between the Newtonian and Cowling results. We compare the results
obtained with homogeneous, polytropic and realistic equations of state and find
that the frequencies depend only on the rotation rate and on the compactness
parameter (M/R), being almost independent of the equation of state. Our
numerical results for realistic neutron stars give viscous damping times with
the same dependence on mass and radius as previously estimated, but
systematically larger of about 60%.",0504062v1
2005-04-29,Evidence for a magnitude-dependent bias in the Hamburg/ESO Survey for Damped Lyman-alpha Systems,"We present preliminary results from the Hamburg/ESO survey for Damped
Ly-alpha (hereafter, DLA) Systems. This survey is characterized by (i) the good
knowledge of the biases affecting the parent QSO survey, (ii) the brightness
and (iii) the relatively wide magnitude distribution of the background QSOs.
Therefore, it is well-suited to study possible magnitude-dependent biases in
DLA surveys, such as the one expected from dust obscuration. We have
systematically searched for damped Lyman-alpha line candidates in 5 A
resolution spectra of the 188 QSOs that constitute our statistical sample.
These candidates have later been reobserved with UVES at the ESO--Very Large
Telescope (VLT) for confirmation and accurate N(HI) measurements. In the
redshift range covered by the survey, 19 DLA systems have been discovered. Over
the whole survey, we find that the number density, n(z), and cosmological
density of gas, Omega_gas, have comparable values to the ones obtained by
CORALS (Ellison et al. 2001). However, the number densities of DLA systems n(z)
in two sub-samples of equal absorption distance path defined by the magnitude
of the background QSOs differ by a factor of about 5. We estimate that the
probability that n(z) is equal in the two sub-samples is < 0.003. A similar,
only slightly less significant difference is found for Omega_gas.",0504657v1
2005-07-06,The free precession and libration of Mercury,"An analysis based on the direct torque equations including tidal dissipation
and a viscous core-mantle coupling is used to determine the damping time scales
of O(10^5) years for free precession of the spin about the Cassini state and
free libration in longitude for Mercury. The core-mantle coupling dominates the
damping over the tides by one to two orders of magnitude for the plausible
parameters chosen. The short damping times compared with the age of the solar
system means we must find recent or on-going excitation mechanisms if such free
motions are found by the current radar experiments or the future measurement by
the MESSENGER and BepiColombo spacecraft that will orbit Mercury. We also show
that the average precession rate is increased by about 30% over that obtained
from the traditional precession constant because of a spin-orbit resonance
induced contribution by the C_{22} term in the expansion of the gravitational
field. The C_{22} contribution also causes the path of the spin during the
precession to be slightly elliptical with a variation in the precession rate
that is a maximum when the obliquity is a minimum. An observable free
precession will compromise the determination of obliquity of the Cassini state
and hence of C/MR^2 for Mercury, but a detected free libration will not
compromise the determination of the forced libration amplitude and thus the
verification of a liquid core",0507117v1
2005-10-12,Ly-alpha Radiative Transfer in Cosmological Simulations and Application to a z~8 Emitter,"We develop a Ly-alpha radiative transfer (RT) Monte Carlo code for
cosmological simulations.High resolution,along with appropriately treated
cooling can result in simulated environments with very high optical
depths.Thus,solving the Ly-alpha RT problem in cosmological simulations can
take an unrealistically long time.For this reason,we develop methods to speed
up the Ly-alpha RT.With these accelerating methods,along with the
parallelization of the code,we make the problem of Ly-alpha RT in the complex
environments of cosmological simulations tractable.We test the RT code against
simple Ly-alpha emitter models,and then we apply it to the brightest Ly-alpha
emitter of a gasdynamics+N-body Adaptive Refinement Tree (ART) simulation at
z~8.We find that recombination rather than cooling radiation Ly-alpha photons
is the dominant contribution to the intrinsic Ly-alpha luminosity of the
emitter,which is ~4.8x10e43 ergs/s.The size of the emitter is pretty
small,making it unresolved for currently available instruments.Its spectrum
before adding the Ly-alpha Gunn-Peterson absorption (GP) resembles that of
static media,despite some net inward radial peculiar motion.This is because for
such high optical depths as those in ART simulations,velocities of order some
hundreds km/s are not important.We add the GP in two ways.First we assume no
damping wing,corresponding to the situation where the emitter lies within the
HII region of a very bright quasar,and second we allow for the damping
wing.Including the damping wing leads to a maximum line brightness suppression
by roughly a factor of ~62.The line fluxes,even though quite faint for current
ground-based telescopes,should be within reach for JWST.",0510347v2
2005-12-05,Kinematics and star formation activity in the z=2.03954 damped Lyman-alpha system towards PKS 0458-020,"We present UVES observations of the log N(HI)= 21.7 damped Lyman-alpha system
at z=2.03954 towards the quasar PKS 0458-020. HI Lyman-alpha emission is
detected in the center of the damped Lyman-alpha absorption trough.
Metallicities are derived for MgII, SiII, PII, CrII, MnII, FeII and ZnII and
are found to be -1.21\pm0.12, -1.28\pm0.20, -1.54\pm0.11, -1.66\pm0.10,
-2.05\pm0.11, -1.87\pm0.11, -1.22\pm0.10, respectively, relative to solar. The
depletion factor is therefore of the order of [Zn/Fe]=0.65. We observe metal
absorption lines to be blueshifted compared to the Lyman-alpha emission up to a
maximum of 100 and 200 km/s for low and high-ionization species respectively.
This can be interpreted either as the consequence of rotation in a large
(~7kpc) disk or as the imprint of a galactic wind. The star formation rate
(SFR) derived from the Lyman-alpha emission, 1.6 solar masses/yr, is compared
with that estimated from the observed CII* absorption. No molecular hydrogen is
detected in our data, yielding a molecular fraction f<-6.52. This absence of H2
can be explained as the consequence of a high ambient UV flux which is one
order of magnitude larger than the radiation field in the ISM of our Galaxy and
originates in the observed emitting region.",0512118v1
2006-02-14,On the magnetic structure and wind parameter profiles of Alfven wave driven winds in late-type supergiant stars,"Cool stars at giant and supergiant evolutionary phases present low velocity
and high density winds, responsible for the observed high mass-loss rates.
Although presenting high luminosities, radiation pressure on dust particles is
not sufficient to explain the wind acceleration process. Among the possible
solutions to this still unsolved problem, Alfven waves are, probably, the most
interesting for their high efficiency in transfering energy and momentum to the
wind. Typically, models of Alfven wave driven winds result in high velocity
winds if they are not highly damped. In this work we determine
self-consistently the magnetic field geometry and solve the momentum, energy
and mass conservation equations, to demonstrate that even a low damped Alfven
wave flux is able to reproduce the low velocity wind. We show that the magnetic
fluxtubes expand with a super-radial factor S>30 near the stellar surface,
larger than that used in previous semi-empirical models. The rapid expansion
results in a strong spatial dilution of the wave flux. We obtained the wind
parameter profiles for a typical supergiant star of 16 M_sun. The wind is
accelerated in a narrow region, coincident with the region of high divergence
of the magnetic field lines, up to 100 km/s. For the temperature, we obtained a
slight decrease near the surface for low damped waves, because the wave heating
mechanism is less effective than the radiative losses. The peak temperature
occurs at 1.5 r_0 reaching 6000 K. Propagating outwards, the wind cools down
mainly due to adiabatic expansion.",0602305v1
2006-03-17,Electron impact excitation of Helium-like ions up to n=4 levels including radiation damping,"Helium-like ions provide the most important X-ray spectral diagnostics in
high temperature fusion and astrophysical plasmas. We previously presented
computed collision strengths for O~VII including relativistic fine structure,
levels up to the $n=4$ complex and radiation damping of autoionizing
resonances. We have extended this work to other He-like ions (N, Ne, Mg, Al,
Si, S, Ca). The calculations are carried out using the Breit-Pauli R-matrix
(BPRM) method with a 31-level eigenfunction expansion. Collision strengths for
the principal lines important in X-ray plasma diagnostics, w, x, y and z,
corresponding to the 4 transitions to the ground level 1s^2(^1S_0) <-
1s2p(^1P^o_1), 1s2p(^3P^o_2), 1s2p(^3P^o_1), 1s2s(^3S_1), are explicitly shown.
We find the effect of radiation damping to be significant for the forbidden
transitions in heavier He-like ions, which should affect the diagnostic line
ratios. We extrapolated the collision strengths to their values at infinite
energy using the Burgess-Tully extrapolation technique. This is required to
calculate the Maxwellian average collision strengths at high temperature. We
show that the coupling between dipole allowed and inter-combination transitions
affects increasingly the effective collision strengths for the n ^1S_0 - n'
^3P_1 transition as the charge of the ion increases. This clearly affects the
treatment of the extrapolation toward the infinite energy point of the
collision strength. This work is carried out as part of the Iron Project-RmaX
Network.",0603482v1
2006-07-25,Metal-rich Damped/sub-Damped Lyman-alpha Quasar Absorbers at z<1,"Damped Lyman-alpha absorbers (DLAs), seen in absorption against a background
quasar, provide the most detailed probes available of element abundances in the
Universe over > 90 % of its age. DLAs can be used to observationally measure
the global mean metallicity in the Universe and its evolution with time.
Paradoxically, these observations are more difficult at lower redshifts, where
the absorber rest-frame UV spectra are cut-off due to the atmospheric
absorption. We present here high-resolution VLT/UVES observations of several
elements contained in three DLAs and one sub-DLA with 0.6<z_abs<0.9. We detect
Mg I, Mg II, Fe II, Zn II, Cr II, Mn II, Ti II and Ca II. Our observations more
than double the high-resolution sample of [Zn/H] at z<1. We also report the
discovery of three metal-rich systems, whereas most previous measurements show
low N(HI)-weighted mean metallicity projecting to about 1/6th solar level at
z=0. We derive [Zn/H]=-0.11+/-0.04 at z_abs=0.725, [Zn/H]=-0.54+/-0.20 at
z_abs=0.740 and [Zn/H]=-0.49+/-0.22 at z_abs=0.652, plus one additional upper
limit ([Zn/H]<-0.36 at z_abs=0.842). These measurements confirm the existence
of quasar absorbers with relatively high metallicities based on abundance
estimates free from the effect of dust depletion. Possible implications of
these results for the metallicity of neutral gas phase in the past ~ 8 Gyr are
presented and compared with models.",0607561v1
1994-09-29,Avalanches in the Weakly Driven Frenkel-Kontorova Model,"A damped chain of particles with harmonic nearest-neighbor interactions in a
spatially periodic, piecewise harmonic potential (Frenkel-Kontorova model) is
studied numerically. One end of the chain is pulled slowly which acts as a weak
driving mechanism. The numerical study was performed in the limit of infinitely
weak driving. The model exhibits avalanches starting at the pulled end of the
chain. The dynamics of the avalanches and their size and strength distributions
are studied in detail. The behavior depends on the value of the damping
constant. For moderate values a erratic sequence of avalanches of all sizes
occurs. The avalanche distributions are power-laws which is a key feature of
self-organized criticality (SOC). It will be shown that the system selects a
state where perturbations are just able to propagate through the whole system.
For strong damping a regular behavior occurs where a sequence of states
reappears periodically but shifted by an integer multiple of the period of the
external potential. There is a broad transition regime between regular and
irregular behavior, which is characterized by multistability between regular
and irregular behavior. The avalanches are build up by sound waves and shock
waves. Shock waves can turn their direction of propagation, or they can split
into two pulses propagating in opposite directions leading to transient
spatio-temporal chaos. PACS numbers: 05.70.Ln,05.50.+q,46.10.+z",9409006v1
1998-06-21,Collective intersubband transitions in quantum wells: a comparative density-functional study,"We use time-dependent (current) density functional theory to study collective
transitions between the two lowest subbands in GaAs/AlGaAs quantum wells. We
focus on two systems where experimental results are available: a wide single
and a narrow asymmetric double well. The aim is to calculate frequency and
linewidth of collective electronic modes damped via electron-electron
interaction only. Since Landau damping is not effective here, the dominant
damping mechanism involves dynamical exchange-correlation effects such as
multipair production. To capture these effects, one has to go beyond the widely
used adiabatic local density approximation (ALDA) and include retardation. We
perform a comparative study of two approaches which fall in this category: the
dynamical extension of the ALDA by Gross and Kohn, and a more recent method
which treats exchange and correlation beyond the ALDA as viscoelastic stresses
in the electron liquid. We find that the former method is more robust: it
performs similarly for strongly different degrees of collectivity of the
electronic motion. Results for quantum wells compare reasonably to experiment,
with a tendency towards overdamping. By contrast, the viscoelastic approach is
superior for systems where the electron dynamics is predominantly collective,
but breaks down if the local velocity field is too rapidly varying, as in the
case of a single-electron-like behavior such as tunneling through a potential
barrier.",9806252v1
1998-11-27,Renormalization group analysis of the quantum non-linear sigma model with a damping term,"We investigate the behavior of the zero-temperature quantum non-linear sigma
model in d dimensions in the presence of a damping term of the form f(w)~
|w|^alpha, with 1 \le alpha <2. We find two fixed points: a spin-wave fixed
point FP1 showing a dynamic scaling exponent z=1 and a dissipative fixed point
FP2 with z>1. In the framework of the \epsilon-expansion it is seen that there
is a range of values alpha_*(d) \le alpha \le 2 where the point FP1 is stable
with respect to FP2, so that the system realizes a z=1 quantum critical
behavior even in the presence of a dissipative term. However, reasonable
arguments suggest that in d=2 this range is very narrow. In the broken symmetry
phase we discuss a phenomenological scaling approach, treating damping as a
perturbation of the ordered ground state. The relation of these results with
the pseudogap effect observed in underdoped layered cuprates is discussed.",9811392v2
1999-12-14,Spinwave damping in the two-dimensional ferromagnetic XY model,"The effect of damping of spinwaves in a two-dimensional classical
ferromagnetic XY model is considered. The damping rate $\Gamma_{q}$ is
calculated using the leading diagrams due to the quartic-order deviations from
the harmonic spin Hamiltonian. The resulting four-dimensional integrals are
evaluated by extending the techniques developed by Gilat and others for
spectral density types of integrals. $\Gamma_{q}$ is included into the memory
function formalism due to Reiter and Solander, and Menezes, to determine the
dynamic structure function $S(q,\omega)$. For the infinite sized system, the
memory function approach is found to give non-divergent spinwave peaks, and a
smooth nonzero background intensity (``plateau'' or distributed intensity) for
the whole range of frequencies below the spinwave peak. The background
amplitude relative to the spinwave peak rises with temperature, and eventually
becomes higher than the spinwave peak, where it appears as a central peak. For
finite-sized systems, there are multiple sequences of weak peaks on both sides
of the spinwave peaks whose number and positions depend on the system size and
wavevector in integer units of $2\pi/L$. These dynamical finite size effects
are explained in the memory function analysis as due to either spinwave
difference processes below the spinwave peak or sum processes above the
spinwave peak. These features are also found in classical Monte Carlo --
Spin-Dynamics simulations.",9912241v1
2002-01-25,Time-dependent current density functional theory for the linear response of weakly disordered systems,"This paper develops a quantitatively accurate first-principles description
for the frequency and the linewidth of collective electronic excitations in
inhomogeneous weakly disordered systems. A finite linewidth in general has
intrinsic and extrinsic sources. At low temperatures and outside the region
where electron-phonon interaction occurs, the only intrinsic damping mechanism
is provided by electron-electron interaction. This kind of intrinsic damping
can be described within time-dependent density-functional theory (TDFT), but
one needs to go beyond the adiabatic approximation and include retardation
effects. It was shown previously that a density-functional response theory that
is local in space but nonlocal in time has to be constructed in terms of the
currents, rather than the density. This theory will be reviewed in the first
part of this paper. For quantitatively accurate linewidths, extrinsic
dissipation mechanisms, such as impurities or disorder, have to be included. In
the second part of this paper, we discuss how extrinsic dissipation can be
described within the memory function formalism. We first review this formalism
for homogeneous systems, and then present a synthesis of TDFT with the memory
function formalism for inhomogeneous systems, to account simultaneously for
intrinsic and extrinsic damping of collective excitations. As example, we
calculate frequencies and linewidths of intersubband plasmons in a 40 nm wide
GaAs/AlGaAs quantum well.",0201483v1
2003-06-10,Oscillations of Bose-Einstein condensates with vortex lattices. II. Finite temperatures,"We derive the finite temperature oscillation modes of a harmonically confined
Bose-Einstein condensed gas undergoing rigid body rotation supported by a
vortex lattice in the condensate. The hydrodynamic modes separate into two
classes corresponding to in-phase (center-of-mass) and counter-phase (relative)
oscillations of the thermal cloud and the condensate. The in- and counter-phase
oscillations are independent of each other in the case where the thermal cloud
is inviscid for all modes studied, except the radial pulsations which couple
them because the pressure perturbations of the condensate and the thermal cloud
are governed by different adiabatic indices. If the thermal cloud is viscous,
the two classes of oscillations are coupled, i.e. each type of motion involves
simultaneously mass and entropy currents. The counter-phase oscillations are
damped by the mutual friction between the condensate and the thermal cloud
mediated by the vortex lattice. The damping is large for the values of the
drag-to-lift ratio of the order of unity and becomes increasingly ineffective
in either limit of small or large friction. An experimental measurement of a
subset of these oscillation modes and their damping rates can provide
information on the values of the phenomenological mutual friction coefficients,
and hence the quasiparticle-vortex scattering processes in dilute atomic Bose
gases.",0306245v2
2004-05-14,Thermoelastic relaxation in elastic structures with applications to thin plates,"A new result enables direct calculation of thermoelastic damping in vibrating
elastic solids. The mechanism for energy loss is thermal diffusion caused by
inhomogeneous deformation, flexure in thin plates. The general result is
combined with the Kirchhoff assumption to obtain a new equation for the
flexural vibration of thin plates incorporating thermoelastic loss as a damping
term. The thermal relaxation loss is inhomogeneous and depends upon the local
state of vibrating flexure, specifically, the principal curvatures at a given
point on the plate. Thermal loss is zero at points where the principal
curvatures are equal and opposite, that is, saddle shaped or pure anticlastic
deformation. Conversely, loss is maximum at points where the curvatures are
equal, that is, synclastic or spherical flexure. The influence of modal
urvature on the thermoelastic damping is described through a modal
pparticipation factor. The effect of transverse thermal diffusion on plane wave
propagation is also examined. It is shown that transverse diffusion effects are
always small provided the plate thickness is far greater than the thermal
phonon mean free path, a requirement for the validity of the classical theory
of heat transport. These results generalize Zener's theory of thermoelastic
loss in beams and are useful in predicting mode widths in MEMS and NEMS
oscillators.",0405323v2
2004-12-18,Fluctuations of the Magnetization in Thin Films due to Conduction Electrons,"A detailed analysis of damping and noise due to a {\it sd}-interaction in a
thin ferromagnetic film sandwiched between two large normal metal layers is
carried out. The magnetization is shown to obey in general a non-local equation
of motion which differs from the the Gilbert equation and is extended to the
non-adiabatic regime. To lowest order in the exchange interaction and in the
limit where the Gilbert equation applies, we show that the damping term is
enhanced due to interfacial effects but it also shows oscillations as a
function of the film thickness. The noise calculation is however carried out to
all orders in the exchange coupling constant. The ellipticity of the precession
of the magnetization is taken into account. The damping is shown to have a
Gilbert form only in the adiabatic limit while the relaxation time becomes
strongly dependent on the geometry of the thin film. It is also shown that the
induced noise characteristic of sd-exchange is inherently colored in character
and depends on the symmetry of the Hamiltonian of the magnetization in the
film. We show that the sd-noise can be represented in terms of an external
stochastic field which is white only in the adiabatic regime. The temperature
is also renormalized by the spin accumulation in the system. For large
intra-atomic exchange interactions, the Gilbert-Brown equation is no longer
valid.",0412510v1
2005-04-21,Ultrafast dynamics of coherent optical phonons and nonequilibrium electrons in transition metals,"The femtosecond optical pump-probe technique was used to study dynamics of
photoexcited electrons and coherent optical phonons in transition metals Zn and
Cd as a function of temperature and excitation level. The optical response in
time domain is well fitted by linear combination of a damped harmonic
oscillation because of excitation of coherent $E_{2g}$ phonon and a
subpicosecond transient response due to electron-phonon thermalization. The
electron-phonon thermalization time monotonically increases with temperature,
consistent with the thermomodulation scenario, where at high temperatures the
system can be well explained by the two-temperature model, while below
$\approx$ 50 K the nonthermal electron model needs to be applied. As the
lattice temperature increases, the damping of the coherent $E_{2g}$ phonon
increases, while the amplitudes of both fast electronic response and the
coherent $E_{2g}$ phonon decrease. The temperature dependence of the damping of
the $E_{2g}$ phonon indicates that population decay of the coherent optical
phonon due to anharmonic phonon-phonon coupling dominates the decay process. We
present a model that accounts for the observed temperature dependence of the
amplitude assuming the photoinduced absorption mechanism, where the signal
amplitude is proportional to the photoinduced change in the quasiparticle
density. The result that the amplitude of the $E_{2g}$ phonon follows the
temperature dependence of the amplitude of the fast electronic transient
indicates that under the resonant condition both electronic and phononic
responses are proportional to the change in the dielectric function.",0504540v1
2005-10-10,Quantum master equation descriptions of a nanomechanical resonator coupled to a single-electron transistor,"We analyse the quantum dynamics of a nanomechanical resonator coupled to a
normal-state single-electron transistor (SET). Starting from a microscopic
description of the system, we derive a master equation for the SET island
charge and resonator which is valid in the limit of weak electro-mechanical
coupling. Using this master equation we show that, apart from brief transients,
the resonator always behaves like a damped harmonic oscillator with a shifted
frequency and relaxes into a thermal-like steady state. Although the behaviour
remains qualitatively the same, we find that the magnitude of the resonator
damping rate and frequency shift depend very sensitively on the relative
magnitudes of the resonator period and the electron tunnelling time. Maximum
damping occurs when the electrical and mechanical time-scales are the same, but
the frequency shift is greatest when the resonator moves much more slowly than
the island charge. We then derive reduced master equations which describe just
the resonator dynamics. By making slightly different approximations, we obtain
two different reduced master equations for the resonator. Apart from minor
differences, the two reduced master equations give rise to a consistent picture
of the resonator dynamics which matches that obtained from the master equation
including the SET island charge.",0510236v1
2006-05-19,Enhancement of noncontact friction between closely spaced bodies by two-dimensional systems,". We consider the effect of an external bias voltage and the spatial
variation of the surface potential, on the damping of cantilever vibrations.
The electrostatic friction is due to energy losses in the sample created by the
electromagnetic field from the oscillating charges induced on the surface of
the tip by the bias voltage and spatial variation of the surface potential. A
similar effect arises when the tip is oscillating in the electrostatic field
created by charged defects in a dielectric substrate. The electrostatic
friction is compared with the van der Waals friction originating from the
fluctuating electromagnetic field due to quantum and thermal fluctuation of the
current density inside the bodies. We show that the electrostatic and van der
Waals friction can be greatly enhanced if on the surfaces of the sample and the
tip there are two-dimension (2D) systems, e.g. a 2D-electron system or
incommensurate layers of adsorbed ions exhibiting acoustic vibrations. We show
that the damping of the cantilever vibrations due to the electrostatic friction
may be of similar magnitude as the damping observed in recent experiments of
Stipe \textit{et al} [B.C.Stipe, H.J.Mamin, T.D.Stowe, T.W.Kenny, and D.Rugar,
Phys.Rev. Lett.% \textbf{87}, 0982001]. We also show that at short separation
the van der Waals friction may be large enough to be measured experimentally.",0605480v1
2006-09-12,Slowing down Josephson vortex lattice in Bi_2Sr_2CaCu_2O_{8+d} with pancake vortices,"We study theoretically and experimentally influence of pancake vortices on
motion of the Josephson vortex lattice in layered high-temperature
superconductors. Mobility of the Josephson vortices in layered superconductors
is strongly suppressed by small amount of pancake-vortex stacks. Moving
Josephson vortex lattice forces oscillating zigzag deformation of the
pancake-vortex stacks contributing to damping. The salient feature of this
contribution is its nonmonotonic dependence on the lattice velocity and the
corresponding voltage. Maximum pancake effect is realized when the Josephson
frequency matches the relaxation frequency of the stacks. The pancake-vortex
damping is strongly suppressed by thermal fluctuations of the pancake vortices.
This theoretical picture was qualitatively confirmed by experiments on two
mesas prepared out of Bi_2Sr_2CaCu_2O_{8+d} whiskers. We found that the
Josephson-vortex flux-flow voltage is very sensitive to small c-axis magnetic
field. The pancake-vortex contribution to the current indeed nonmonotonically
depends on voltage and decreases with increasing temperature and in-plane
magnetic field. We also found that irradiation with heavy ions has no
noticeable direct influence on motion of the Josephson vortices but
dramatically reduces the pancake-vortex contribution to the damping of the
Josephson vortex lattice at low temperatures.",0609262v2
2003-08-24,Numerical analysis of quasinormal modes in nearly extremal Schwarzschild-de Sitter spacetimes,"We calculate high-order quasinormal modes with large imaginary frequencies
for electromagnetic and gravitational perturbations in nearly extremal
Schwarzschild-de Sitter spacetimes. Our results show that for low-order
quasinormal modes, the analytical approximation formula in the extremal limit
derived by Cardoso and Lemos is a quite good approximation for the quasinormal
frequencies as long as the model parameter $r_1\kappa_1$ is small enough, where
$r_1$ and $\kappa_1$ are the black hole horizon radius and the surface gravity,
respectively. For high-order quasinormal modes, to which corresponds
quasinormal frequencies with large imaginary parts, on the other hand, this
formula becomes inaccurate even for small values of $r_1\kappa_1$. We also find
that the real parts of the quasinormal frequencies have oscillating behaviors
in the limit of highly damped modes, which are similar to those observed in the
case of a Reissner-Nordstr{\"" o}m black hole. The amplitude of oscillating
${\rm Re(\omega)}$ as a function of ${\rm Im}(\omega)$ approaches a non-zero
constant value for gravitational perturbations and zero for electromagnetic
perturbations in the limit of highly damped modes, where $\omega$ denotes the
quasinormal frequency. This means that for gravitational perturbations, the
real part of quasinormal modes of the nearly extremal Schwarzschild-de Sitter
spacetime appears not to approach any constant value in the limit of highly
damped modes. On the other hand, for electromagnetic perturbations, the real
part of frequency seems to go to zero in the limit.",0308077v4
2006-02-01,Radiation Damping in Einstein-Aether Theory,"This work concerns the loss of energy of a material system due to
gravitational radiation in Einstein-aether theory-an alternative theory of
gravity in which the metric couples to a dynamical, timelike, unit-norm vector
field. Derived to lowest post-Newtonian order are waveforms for the metric and
vector fields far from a nearly Newtonian system and the rate of energy
radiated by the system. The expressions depend on the quadrupole moment of the
source, as in standard general relativity, but also contain monopolar and
dipolar terms. There exists a one-parameter family of Einstein-aether theories
for which only the quadrupolar contribution is present, and for which the
expression for the damping rate is identical to that of general relativity to
the order worked to here. This family cannot yet be declared observationally
viable, since effects due to the strong internal fields of bodies in the actual
systems used to test the damping rate are not included.",0602004v5
1998-02-20,Real-time Relaxation and Kinetics in Hot Scalar QED: Landau Damping,"The real time evolution of field condensates with soft length scales
k^{-1}>(eT)^{-1} is solved in hot scalar electrodynamics, with a view towards
understanding relaxational phenomena in the QGP and the electroweak plasma. We
find that transverse gauge invariant non-equilibrium expectation values of
fields relax via {\em power laws} to asymptotic amplitudes that are determined
by the quasiparticle poles. The long time relaxational dynamics and relevant
time scales are determined by the behaviour of the retarded self-energy not at
the small frequencies, but at the Landau damping thresholds. This explains the
presence of power laws and not of exponential decay. Furthermore, we derive the
influence functional, the Langevin equation and the fluctuation-dissipation
theorem for the soft modes, identifying the correlation functions that emerge
in the classical limit. We show that a Markovian approximation fails to
describe the dynamics {\em both} at short and long times. We also introduce a
novel kinetic approach that goes beyond the standard Boltzmann equation and
incorporates off-shell processes and find that the distribution function for
soft quasiparticles relaxes with a power law through Landau damping. We also
find an unusual dressing dynamics of bare particles and anomalous (logarithmic)
relaxation of hard quasiparticles.",9802370v2
2003-03-04,Asymptotic quasinormal modes of Reissner-Nordström and Kerr black holes,"According to a recent proposal, the so-called Barbero-Immirzi parameter of
Loop Quantum Gravity can be fixed, using Bohr's correspondence principle, from
a knowledge of highly-damped black hole oscillation frequencies. Such
frequencies are rather difficult to compute, even for Schwarzschild black
holes. However, it is now quite likely that they may provide a fundamental link
between classical general relativity and quantum theories of gravity. Here we
carry out the first numerical computation of very highly damped quasinormal
modes (QNM's) for charged and rotating black holes. In the Reissner-Nordstr\""om
case QNM frequencies and damping times show an oscillatory behaviour as a
function of charge. The oscillations become faster as the mode order increases.
At fixed mode order, QNM's describe spirals in the complex plane as the charge
is increased, tending towards a well defined limit as the hole becomes
extremal. Kerr QNM's have a similar oscillatory behaviour when the angular
index $m=0$. For $l=m=2$ the real part of Kerr QNM frequencies tends to
$2\Omega$, $\Omega$ being the angular velocity of the black hole horizon, while
the asymptotic spacing of the imaginary parts is given by $2\pi T_H$.",0303029v3
2005-01-28,Summation of divergent series and Borel summability for strongly dissipative equations with periodic or quasi-periodic forcing terms,"We consider a class of second order ordinary differential equations
describing one-dimensional systems with a quasi-periodic analytic forcing term
and in the presence of damping. As a physical application one can think of a
resistor-inductor-varactor circuit with a periodic (or quasi-periodic) forcing
function, even if the range of applicability of the theory is much wider. In
the limit of large damping we look for quasi-periodic solutions which have the
same frequency vector of the forcing term, and we study their analyticity
properties in the inverse of the damping coefficient. We find that already the
case of periodic forcing terms is non-trivial, as the solution is not analytic
in a neighbourhood of the origin: it turns out to be Borel-summable. In the
case of quasi-periodic forcing terms we need Renormalization Group techniques
in order to control the small divisors arising in the perturbation series. We
show the existence of a summation criterion of the series in this case also,
but, however, this can not be interpreted as Borel summability.",0501500v1
1997-11-17,Fusion and Binary-Decay Mechanisms in the $^{35}$Cl+$^{24}$Mg System at E/A $\approx$ 8 MeV/Nucleon,"Compound-nucleus fusion and binary-reaction mechanisms have been investigated
for the $^{35}$Cl+$^{24}$Mg system at an incident beam energy of E$_{Lab}$= 282
MeV. Charge distributions, inclusive energy spectra, and angular distributions
have been obtained for the evaporation residues and the binary fragments.
Angle-integrated cross sections have been determined for evaporation residues
from both the complete and incomplete fusion mechanisms. Energy spectra for
binary fragment channels near to the entrance-channel mass partition are
characterized by an inelastic contribution that is in addition to a fully
energy damped component. The fully damped component which is observed in all
the binary mass channels can be associated with decay times that are comparable
to, or longer than the rotation period. The observed mass-dependent cross
sections for the fully damped component are well reproduced by the fission
transition-state model, suggesting a fusion followed by fission origin. The
present data cannot, however, rule out the possibility that a long-lived
orbiting mechanism accounts for part or all of this yield.",9711005v1
1996-12-31,Fluid Models for Kinetic Effects on Coherent Nonlinear Alfven Waves. II. Numerical Solutions,"The influence of various kinetic effects (e.g. Landau damping, diffusive and
collisional dissipation, and finite Larmor radius terms) on the nonlinear
evolution of finite amplitude Alfvenic wave trains in a finite-beta environment
is systematically investigated using a novel, kinetic nonlinear Schrodinger
(KNLS) equation. The dynamics of Alfven waves is sensitive to the sense of
polarization as well as the angle of propagation with respect to the ambient
magnetic field. Numerical solution for the case with Landau damping reveals the
formation of dissipative structures, which are quasi-stationary, S-polarized
directional (and rotational) discontinuities which self-organize from parallel
propagating, linearly polarized waves. Parallel propagating circularly
polarized packets evolve to a few circularly polarized Alfven harmonics on
large scales. Stationary arc-polarized rotational discontinuities form from
obliquely propagating waves. Collisional dissipation, even if weak, introduces
enhanced wave damping when beta is very close to unity. Cyclotron motion
effects on resonant particle interactions introduce cyclotron resonance into
the nonlinear Alfven wave dynamics.",9612018v1
2000-09-06,"Design, fabrication and measurement of the first rounded damped detuned accelerator structure (RDDS1)","As a joint effort in the JLC/NLC research program, we have developed a new
type of damped detuned accelerator structure with optimized round-shaped
cavities (RDDS). This paper discusses some important R&D aspects of the first
structure in this series (RDDS1). The design aspects covered are the cell
design with sub-MHz precision, HOM detuning, coupling and damping technique and
wakefield simulation. The fabrication issues covered are ultra-precision cell
machining with micron accuracy, assembly and diffusion bonding technologies to
satisfactorily meet bookshelf, straightness and cell rotational alignment
requirements. The measurements described are the RF properties of single
cavities and complete accelerator section, as well as wakefields from the ASSET
tests at SLAC. Finally, future improvements are also discussed.",0009025v1
2000-12-10,Chaotic atomic population oscillations between two coupled Bose-Einstein condensates with time-dependent asymmetric trap potential,"We have investigated the chaotic atomic population oscillations between two
coupled Bose-Einstein condensates (BEC) with time-dependent asymmetric trap
potential. In the perturbative regime, the population oscillations can be
described by the Duffing equation, and the chaotic oscillations near the
separatrix solution are analyzed. The sufficient-necessary conditions for
stable oscillations depend on the physical parameters and initial conditions
sensitively. The first-order necessary condition indicates that the Melnikov
function is equal to zero, so the stable oscillations are Melnikov chaotic. For
the ordinary parameters and initial conditions, the chaotic dynamics is
simulated with numerical calculation. If the damping is absent, with the
increasing of the trap asymmetry, the regular oscillations become chaotic
gradually, the corresponding stroboscopic Poincare sections (SPS) vary from a
single island to more islands, and then the chaotic sea. For the completely
chaotic oscillations, the long-term localization disappears and the short-term
localization can be changed from one of the BECs to the other through the route
of Rabi oscillation. When there exists damping, the stationary chaos
disappears, the transient chaos is a common phenomenon before regular stable
frequency locked oscillations. And proper damping can keep localization
long-lived.",0012043v1
2003-01-23,Revivals and entanglement from initially entangled mixed states of a damped Jaynes-Cummings model,"An exact density matrix of a phase-damped Jaynes - Cummings model (JCM) with
entangled Bell-like initial states formed from a model two-state atom and sets
of adjacent photon number states of a single mode radiation field is presented.
The entanglement of the initial states and the subsequent time evolution is
assured by finding a positive lower bound on the concurrence of local 2x2
projections of the full 2xinfinity JCM density matrix. It is found that the
time evolution of the lower bound of the concurrence systematically captures
the corresponding collapse and revival features in atomic inversion, relative
entropies of atomic and radiation, mutual entropy, and quantum deficit. The
atom and radiation subsystems exhibit alternating sets of collapses and
revivals in a complementary fashion due to the initially mixed states of the
atom and radiation employed here. This is in contrast with the result obtained
when the initial state of the dissipationless system is a factored pure state
of atom and radiation, where the atomic and radiation entropies are necessarily
the same. The magnitudes of the entanglement lower bound and the atomic and
radiation revivals become larger as both magnitude and phase of the Bell-like
initial state contribution increases. The time evolution of the entropy
difference of the total system and that of the radiation subsystem exhibits
negative regions called ""supercorrelated"" states which do not appear in the
atomic subsystem. Entangled initial states are found to enhance this
supercorrelated feature. Finally, the effect of phase damping is to randomize
both the subsystems for asymptotically long times .",0301126v1
2003-03-18,A Method for Modeling Decoherence on a Quantum Information Processor,"We develop and implement a method for modeling decoherence processes on an
N-dimensional quantum system that requires only an $N^2$-dimensional quantum
environment and random classical fields. This model offers the advantage that
it may be implemented on small quantum information processors in order to
explore the intermediate regime between semiclassical and fully quantum models.
We consider in particular $\sigma_z\sigma_z$ system-environment couplings which
induce coherence (phase) damping, though the model is directly extendable to
other coupling Hamiltonians. Effective, irreversible phase-damping of the
system is obtained by applying an additional stochastic Hamiltonian on the
environment alone, periodically redressing it and thereby irreversibliy
randomizing the system phase information that has leaked into the environment
as a result of the coupling. This model is exactly solvable in the case of
phase-damping, and we use this solution to describe the model's behavior in
some limiting cases. In the limit of small stochastic phase kicks the system's
coherence decays exponentially at a rate which increases linearly with the kick
frequency. In the case of strong kicks we observe an effective decoupling of
the system from the environment. We present a detailed implementation of the
method on an nuclear magnetic resonance quantum information processor.",0303115v1
2007-05-11,Ground-state cooling of a micromechanical oscillator: generalized framework for cold damping and cavity-assisted cooling schemes,"We provide a general framework to describe cooling of a micromechanical
oscillator to its quantum ground state by means of radiation-pressure coupling
with a driven optical cavity. We apply it to two experimentally realized
schemes, back-action cooling via a detuned cavity and cold-damping
quantum-feedback cooling, and we determine the ultimate quantum limits of both
schemes for the full parameter range of a stable cavity. While both allow to
reach the oscillator's quantum ground state, we find that back-action cooling
is more efficient in the good cavity limit, i.e. when the cavity bandwidth is
smaller than the mechanical frequency, while cold damping is more suitable for
the bad cavity limit. The results of previous treatments are recovered as
limiting cases of specific parameter regimes.",0705.1728v6
2007-11-08,Solving non-linear equations of longitudinal and transverse electron waves in collisionless Maxwellian plasma,"We have considered an expansion of solutions of the non-linear equations for
both longitudinal and transverse waves in collisionless Maxwellian plasma in
series of non-damping overtones of the field E(x,t) and electron velocity
distribution function f=f(0) +f(1) where f(0) is background Maxwellian electron
distribution function and f(1) is perturbation. The electrical field and
perturbation f(1) are presented as a series of non-damping harmonics with
increasing frequencies of the order n and the same propagation speed. It is
shown presence of recurrent relations for arising overtones. Convergence of the
series is provided by a power law parameter series convergence. There are
proposed also successive procedures of cutting off the distribution function
f(1) to the condition of positivity f near the singularity points where kinetic
equation becomes inapplicable. In this case, at poles absence the solution
reduces to non-damping Vlasov waves (oscillations). In the case of transverse
waves, dispersion equation has two roots, corresponding to the branches of fast
electromagnetic and slow electron waves. There is noted a possibility of
experimental testing appearing exotic results with detecting frequencies and
amplitudes of n-order overtones.",0711.1321v8
2008-02-14,Influence of an inner disc on the orbital evolution of massive planets migrating in resonance,"The formation of resonant pairs of planets in exoplanetary systems involves
planetary migration in the protoplanetary disc. After a resonant capture, the
subsequent migration in this configuration leads to a large increase of
planetary eccentricities if no damping mechanism is applied. This has led to
the conclusion that the migration of resonant planetary systems cannot occur
over large radial distances and has to be terminated sufficiently rapidly
through disc dissipation.
  In this study, we investigate whether the presence of an inner disc might
supply an eccentricity damping of the inner planet, and if this effect could
explain the observed eccentricities in some systems. To investigate the
influence of an inner disc, we first compute hydrodynamic simulations of giant
planets orbiting with a given eccentricity around an inner gas disc, and
measure the effect of the latter on the planetary orbital parameters. We then
perform detailed long term calculations of the GJ 876 system. We also run
N-body simulations with artificial forces on the planets mimicking the effects
of the inner and outer discs.
  We find that the influence of the inner disc can not be neglected, and that
it might be responsible for the observed eccentricities. In particular, we
reproduce quite well the orbital parameters of a few systems engaged in 2:1
mean motion resonances: GJ 876, HD 73526, HD 82943 and HD 128311. Finally, we
derive analytically the effect that the inner disc should have on the inner
planet to reach a specific orbital configuration with a given damping effect of
the outer disc on the outer planet.",0802.2014v1
2008-04-10,Embedded Oscillating Starless Cores,"In a previous paper we demonstrated that non-radial hydrodynamic oscillations
of a thermally-supported (Bonnor-Ebert) sphere embedded in a low-density,
high-temperature medium persist for many periods. The predicted column density
variations and molecular spectral line profiles are similar to those observed
in the Bok globule B68 suggesting that the motions in some starless cores may
be oscillating perturbations on a thermally supported equilibrium structure.
Such oscillations can produce molecular line maps which mimic rotation,
collapse or expansion, and thus could make determining the dynamical state from
such observations alone difficult.
  However, while B68 is embedded in a very hot, low-density medium, many
starless cores are not, having interior/exterior density contrasts closer to
unity. In this paper we investigate the oscillation damping rate as a function
of the exterior density. For concreteness we use the same interior model
employed in Broderick et al. (2007), with varying models for the exterior gas.
We also develop a simple analytical formalism, based upon the linear
perturbation analysis of the oscillations, which predicts the contribution to
the damping rates due to the excitation of sound waves in the external medium.
We find that the damping rate of oscillations on globules in dense molecular
environments is always many periods, corresponding to hundreds of thousands of
years, and persisting over the inferred lifetimes of the globules.",0804.1790v1
2008-05-07,Design of parametrically forced patterns and quasipatterns,"The Faraday wave experiment is a classic example of a system driven by
parametric forcing, and it produces a wide range of complex patterns, including
superlattice patterns and quasipatterns. Nonlinear three-wave interactions
between driven and weakly damped modes play a key role in determining which
patterns are favoured. We use this idea to design single and multi-frequency
forcing functions that produce examples of superlattice patterns and
quasipatterns in a new model PDE with parametric forcing. We make quantitative
comparisons between the predicted patterns and the solutions of the PDE.
Unexpectedly, the agreement is good only for parameter values very close to
onset. The reason that the range of validity is limited is that the theory
requires strong damping of all modes apart from the driven pattern-forming
modes. This is in conflict with the requirement for weak damping if three-wave
coupling is to influence pattern selection effectively. We distinguish the two
different ways that three-wave interactions can be used to stabilise
quasipatterns, and present examples of 12-, 14- and 20-fold approximate
quasipatterns. We identify which computational domains provide the most
accurate approximations to 12-fold quasipatterns, and systematically
investigate the Fourier spectra of the most accurate approximations.",0805.0878v1
2008-06-19,Itinerant spin excitations near the hidden order transition in URu2Si2,"By means of neutron scattering we show that the high-temperature precursor to
the hidden order state of the heavy fermion superconductor URu$_{2}$Si$_{2}$
exhibits heavily damped incommensurate paramagnons whose strong energy
dispersion is very similar to that of the long-lived longitudinal f-spin
excitations that appear below T$_{0}$. Since the underlying local f-exchange is
preserved we expect only the f-d interactions to change across the phase
transition and to cause the paramagnetic damping. The damping exhibits
single-ion behavior independent of wave vector and vanishes below the hidden
order transition. We suggest that this arises from a transition from valence
fluctuations to a hybridized f-d state below T$_{0}$. Here we present evidence
that the itinerant excitations, like those in chromium, are due to Fermi
surface nesting of hole and electron pockets so that the hidden order phase
likely originates from a Fermi-surface instability. We identify wave vectors
that span nested regions of a band calculation and that match the neutron spin
crossover from incommensurate to commensurate on approach to the hidden order
phase.",0806.3137v2
2008-11-21,Specific heat anomalies of open quantum systems,"The evaluation of the specific heat of an open, damped quantum system is a
subtle issue. One possible route is based on the thermodynamic partition
function which is the ratio of the partition functions of system plus bath and
of the bath alone. For the free damped particle it has been shown, however,
that the ensuing specific heat may become negative for appropriately chosen
environments. Being an open system this quantity then naturally must be
interpreted as the change of the specific heat obtained as the difference
between the specific heat of the heat bath coupled to the system degrees of
freedom and the specific heat of the bath alone. While this difference may
become negative, the involved specific heats themselves are always positive;
thus, the known thermodynamic stability criteria are perfectly guaranteed. For
a damped quantum harmonic oscillator, instead of negative values, under
appropriate conditions one can observe a dip in the difference of specific
heats as a function of temperature. Stylized minimal models containing a single
oscillator heat bath are employed to elucidate the occurrence of the anomalous
temperature dependence of the corresponding specific heat values. Moreover, we
comment on the consequences for the interpretation of the density of states
based on the thermal partitionfunction.",0811.3509v2
2008-11-26,Three-dimensional simulations of multiple protoplanets embedded in a protostellar disc,"Protoplanet eccentricities of e >~ H/r can slow or reverse migration, but
previous 2D studies have shown that gravitational scattering cannot maintain
significant planet eccentricities against disc-induced damping. We simulate the
evolution of low-mass protoplanetary swarms in three dimensions. The aim is to
examine both protoplanet survival rates and the dynamical structure of the
resulting planetary systems, and to compare them with 2D simulations. We
present results from a 3D hydrodynamic simulation of eight protoplanets
embedded in a protoplanetary disc. We also present a suite of simulations
performed using an N-body code, modified to include prescriptions for planetary
migration and for eccentricity and inclination damping. These prescriptions
were obtained by fitting analytic formulae to hydrodynamic simulations of
planets embedded in discs with initially eccentric and/or inclined orbits. As
was found in two dimensions, differential migration produces groups of
protoplanets in stable, multiple mean-motion resonances that migrate in
lockstep, preventing prolonged periods of gravitational scattering. In almost
all simulations, this leads to large-scale migration of the protoplanet swarm
into the central star in the absence of a viable stopping mechanism. The
evolution involves mutual collisions, occasional instances of large-scale
scattering, and the frequent formation of the long-lived, co-orbital planet
systems that arise in > 30% of all runs. Disc-induced damping overwhelms
eccentricity and inclination growth due to planet-planet interactions.
Co-orbital planets are a natural outcome of dynamical relaxation in a strongly
dissipative environment, and if observed in nature would imply that such a
period of evolution commonly arises during planetary formation.",0811.4322v1
2008-12-15,Swift-UVOT captures the earliest ultraviolet spectrum of a Gamma Ray Burst,"We present the earliest ever ultraviolet spectrum of a gamma-ray burst (GRB)
as observed with the Swift-UVOT. The GRB 081203A spectrum was observed for 50
seconds with the UV grism starting 251 seconds after the Swift-BAT trigger when
the GRB was of u ~13.4 mag and still rising to its peak optical brightness. The
UV grism spectrum shows a damped Ly-alpha line, Ly-beta, and the Lyman
continuum break at a redshift z = 2.05 +/- 0.01. A model fit to the Lyman
absorption implies log N(HI) = 22.0 +/- 0.2 cm-2, which is typical for GRB host
galaxies with damped Ly-alpha absorbers. This observation of GRB 081203A
demonstrates that for GRBs brighter than v ~14 mag and with 0.5 < z < 3.5 the
UVOT will be able to provide redshifts, and probe for damped Ly-alpha absorbers
within 4-6 minutes from the time of the Swift-BAT trigger.",0812.2943v2
2008-12-16,On the oscillations of dissipative superfluid neutron stars,"We investigate the oscillations of slowly rotating superfluid stars, taking
into account the vortex mediated mutual friction force that is expected to be
the main damping mechanism in mature neutron star cores. Working to linear
order in the rotation of the star, we consider both the fundamental f-modes and
the inertial r-modes. In the case of the (polar) f-modes, we work out an
analytic approximation of the mode which allows us to write down a closed
expression for the mutual friction damping timescale. The analytic result is in
good agreement with previous numerical results obtained using an energy
integral argument. We extend previous work by considering the full range of
permissible values for the vortex drag, e.g. the friction between each
individual vortex and the electron fluid. This leads to the first ever results
for the f-mode in the strong drag regime. Our estimates provide useful insight
into the dependence on, and relevance of, various equation of state parameters.
In the case of the (axial) r-modes, we confirm the existence of two classes of
modes. However, we demonstrate that only one of these sets remains purely axial
in more realistic neutron star models. Our analysis lays the foundation for
companion studies of the mutual friction damping of the r-modes at second order
in the slow-rotation approximation, the first time evolutions for superfluid
neutron star perturbations and also the first detailed attempt at studying the
dynamics of superfluid neutron stars with both a relative rotation between the
components and mutual friction.",0812.3023v1
2009-03-27,Cascade and Damping of Alfvén-Cyclotron Fluctuations: Application to Solar Wind Turbulence,"It is well-recognized that the presence of magnetic fields will lead to
anisotropic energy cascade and dissipation of astrophysical turbulence. With
the diffusion approximation and linear dissipation rates, we study the cascade
and damping of Alfv\'en-cyclotron fluctuations in solar plasmas numerically.
For an isotropic case the steady-state turbulence spectra are nearly isotropic
in the inertial range and can be fitted by a single power-law function with a
spectral index of -3/2, similar to the Iroshnikov-Kraichnan phenomenology.
Beyond the MHD regime the kinetic effects make the spectrum softer at higher
wavenumbers. In the dissipation range the turbulence spectrum cuts off at the
wavenumber, where the damping rate becomes comparable to the cascade rate, and
the cutoff wavenumber changes with the wave propagation direction. The angle
averaged turbulence spectrum of the isotropic model resembles a broken
power-law. Taking into account the Doppler effects, the model naturally
reproduces the broken power-law turbulence spectra observed in the solar wind
and predicts that a higher break frequency always comes along with a softer
dissipation range spectrum that may be caused by the increase of the turbulence
intensity, the reciprocal of the plasma \beta, and/or the angle between the
solar wind velocity and the mean magnetic field. These predictions can be
tested by detailed comparisons with more accurate observations.",0903.4904v1
2009-04-17,Plasmons and polaritons in a semi-infinite plasma and a plasma slab,"Plasmon and polariton modes are derived for an ideal semi-infinite
(half-space) plasma and an ideal plasma slab by using a general, unifying
procedure, based on equations of motion, Maxwell's equations and suitable
boundary conditions. Known results are re-obtained in much a more direct manner
and new ones are derived. The approach consists of representing the charge
disturbances by a displacement field in the positions of the moving particles
(electrons). The dielectric response and the electron energy loss are computed.
The surface contribution to the energy loss exhibits an oscillatory behaviour
in the transient regime near the surfaces. The propagation of an
electromagnetic wave in these plasmas is treated by using the retarded
electromagnetic potentials. The resulting integral equations are solved and the
reflected and refracted waves are computed, as well as the reflection
coefficient. For the slab we compute also the transmitted wave and the
transmission coefficient. Generalized Fresnel's relations are thereby obtained
for any incidence angle and polarization. Bulk and surface plasmon-polariton
modes are identified. As it is well known, the field inside the plasma is
either damped (evanescent) or propagating (transparency regime), and the
reflection coefficient for a semi-infinite plasma exhibits an abrupt
enhancement on passing from the propagating regime to the damped one (total
reflection). Similarly, apart from characteristic oscillations, the reflection
and transmission coefficients for a plasma slab exhibit an appreciable
enhancement in the damped regime.",0904.2662v1
2009-04-29,Synthetic electric fields and phonon damping in carbon nanotubes and graphene,"Smoothly varying lattice strain in graphene affects the Dirac carriers
through a synthetic gauge field. When the lattice strain is time dependent, as
in connection with phononic excitations, the gauge field becomes time dependent
and the synthetic vector potential is also associated with an electric field.
We show that this synthetic electric field has observable consequences. Joule
heating associated with the currents driven by the synthetic electric field
dominates the intrinsic damping, caused by the electron-phonon interaction, of
many acoustic phonon modes of graphene and metallic carbon nanotubes when
including the effects of disorder and Coulomb interactions. Several important
consequences follow from the observation that by time-reversal symmetry, the
synthetic electric field associated with the vector potential has opposite
signs for the two valleys. First, this implies that the synthetic electric
field drives charge-neutral valley currents and is therefore unaffected by
screening. This frequently makes the effects of the synthetic vector potential
more relevant than a competing effect of the scalar deformation potential which
has a much larger bare coupling constant. Second, valley currents decay by
electron-electron scattering (valley Coulomb drag) which causes interesting
temperature dependence of the damping rates. While our theory pertains first
and foremost to metallic systems such as doped graphene and metallic carbon
nanotubes, the underlying mechanisms should also be relevant for semiconducting
carbon nanotubes when they are doped.",0904.4660v1
2009-09-30,Dynamic polarization of graphene by moving external charges: random phase approximation,"We evaluate the stopping and image forces on a charged particle moving
parallel to a doped sheet of graphene by using the dielectric response
formalism for graphene's $\pi$-electron bands in the random phase approximation
(RPA). The forces are presented as functions of the particle speed and the
particle distance for a broad range of charge-carrier densities in graphene. A
detailed comparison with the results from a kinetic equation model reveal the
importance of inter-band single-particle excitations in the RPA model for high
particle speeds. We also consider the effects of a finite gap between graphene
and a supporting substrate, as well as the effects of a finite damping rate
that is included through the use of Mermin's procedure. The damping rate is
estimated from a tentative comparison of the Mermin loss function with a HREELS
experiment. In the limit of low particle speeds, several analytical results are
obtained for the friction coefficient that show an intricate relationship
between the charge-carrier density, the damping rate, and the particle
distance, which may be relevant to surface processes and electrochemistry
involving graphene.",0909.5598v3
2010-02-05,Implementation of an Innovative Bio Inspired GA and PSO Algorithm for Controller design considering Steam GT Dynamics,"The Application of Bio Inspired Algorithms to complicated Power System
Stability Problems has recently attracted the researchers in the field of
Artificial Intelligence. Low frequency oscillations after a disturbance in a
Power system, if not sufficiently damped, can drive the system unstable. This
paper provides a systematic procedure to damp the low frequency oscillations
based on Bio Inspired Genetic (GA) and Particle Swarm Optimization (PSO)
algorithms. The proposed controller design is based on formulating a System
Damping ratio enhancement based Optimization criterion to compute the optimal
controller parameters for better stability. The Novel and contrasting feature
of this work is the mathematical modeling and simulation of the Synchronous
generator model including the Steam Governor Turbine (GT) dynamics. To show the
robustness of the proposed controller, Non linear Time domain simulations have
been carried out under various system operating conditions. Also, a detailed
Comparative study has been done to show the superiority of the Bio inspired
algorithm based controllers over the Conventional Lead lag controller.",1002.1184v1
2010-03-12,Improving the model of emission from spinning dust: effects of grain wobbling and transient spin-up,"Observations continue to support the interpretation of the anomalous
microwave foreground as electric dipole radiation from spinning dust grains as
proposed by Draine and Lazarian (1998ab). In this paper we present a refinement
of the original model by improving the treatment of a number of physical
effects. First, we consider a disk-like grain rotating with angular velocity at
an arbitrary angle with respect to the grain symmetry axis and derive the
rotational damping and excitation coefficients arising from infrared emission,
plasma-grain interactions and electric dipole emission. The angular velocity
distribution and the electric dipole emission spectrum for grains is calculated
using the Langevin equation, for cases both with and without fast internal
relaxation. Our results show that, the peak emissivity of spinning dust,
compared to earlier studies, increases by a factor of ~2 for the Warm Neutral
Medium (WNM), the Warm Ionized Medium (WIM), the Cold Neutral Medium (CNM) and
the Photodissociation Region (PDR), and by a factor ~4 for Reflection Nebulae
(RN). The frequency at the emission peak also increases by factors ~1.4 to ~2
for these media. The increased emission and peak frequency result from the
non-sphericity of grain shape and from the anisotropy in damping and excitation
along directions parallel and perpendicular to the grain symmetry axis. Second,
we provide a detailed numerical study including transient spin-up of grains by
single-ion collisions. The impulses broaden the emission spectrum and increase
the peak emissivity for the CNM, WNM and WIM. In addition, we present an
improved treatment of rotational excitation and damping by infrared emission.",1003.2638v2
2010-03-15,Small BGK waves and nonlinear Landau damping,"Consider 1D Vlasov-poisson system with a fixed ion background and periodic
condition on the space variable. First, we show that for general homogeneous
equilibria, within any small neighborhood in the Sobolev space W^{s,p}
(p>1,s<1+(1/p)) of the steady distribution function, there exist nontrivial
travelling wave solutions (BGK waves) with arbitrary minimal period and
traveling speed. This implies that nonlinear Landau damping is not true in
W^{s,p}(s<1+(1/p)) space for any homogeneous equilibria and any spatial period.
Indeed, in W^{s,p} (s<1+(1/p)) neighborhood of any homogeneous state, the long
time dynamics is very rich, including travelling BGK waves, unstable
homogeneous states and their possible invariant manifolds. Second, it is shown
that for homogeneous equilibria satisfying Penrose's linear stability
condition, there exist no nontrivial travelling BGK waves and unstable
homogeneous states in some W^{s,p} (p>1,s>1+(1/p)) neighborhood. Furthermore,
when p=2,we prove that there exist no nontrivial invariant structures in the
H^{s} (s>(3/2)) neighborhood of stable homogeneous states. These results
suggest the long time dynamics in the W^{s,p} (s>1+(1/p)) and particularly, in
the H^{s} (s>(3/2)) neighborhoods of a stable homogeneous state might be
relatively simple. We also demonstrate that linear damping holds for initial
perturbations in very rough spaces, for linearly stable homogeneous state. This
suggests that the contrasting dynamics in W^{s,p} spaces with the critical
power s=1+(1/p) is a trully nonlinear phenomena which can not be traced back to
the linear level.",1003.3005v1
2010-04-06,Electronic screening and damping in magnetars,"We calculate the screening of the ion-ion potential due to electrons in the
presence of a large background magnetic field, at densities of relevance to
neutron star crusts. Using the standard approach to incorporate electron
screening through the one-loop polarization function, we show that the magnetic
field produces important corrections both at short and long distances. In
extreme fields, realized in highly magnetized neutron stars called magnetars,
electrons occupy only the lowest Landau levels in the relatively low density
region of the crust. Here our results show that the screening length for
Coulomb interactions between ions can be smaller than the inter-ion spacing.
More interestingly, we find that the screening is anisotropic and the screened
potential between two static charges exhibits long range Friedel oscillations
parallel to the magnetic field. This long-range oscillatory behavior is likely
to affect the lattice structure of ions, and can possibly create rod-like
structures in the magnetar crusts. We also calculate the imaginary part of the
electron polarization function which determines the spectrum of electron-hole
excitations and plays a role in damping lattice phonon excitations. We
demonstrate that even for modest magnetic fields this damping is highly
anisotropic and will likely lead to anisotropic phonon heat transport in the
outer neutron star crust.",1004.0926v1
2010-06-25,Decoherence window and electron-nuclear cross-relaxation in the molecular magnet V 15,"Rabi oscillations in the V_15 Single Molecule Magnet (SMM) embedded in the
surfactant DODA have been studied at different microwave powers. An intense
damping peak is observed when the Rabi frequency Omega_R falls in the vicinity
of the Larmor frequency of protons w_N, while the damping time t_R of
oscillations reaches values 10 times shorter than the phase coherence time t_2
measured at the same temperature. The experiments are interpreted by the N-spin
model showing that t_R is directly associated with the decoherence via
electronic/nuclear spin cross-relaxation in the rotating reference frame. It is
shown that this decoherence is accompanied with energy dissipation in the range
of the Rabi frequencies w_N - sigma_e < Omega_R < w_N, where sigma_e is the
mean super-hyperfine field (in frequency units) induced by protons at SMMs.
Weaker damping without dissipation takes place outside this dissipation window.
Simple local field estimations suggest that this rapid cross-relaxation in
resonant microwave field observed for the first time in SMMV_15 should take
place in other SMMs like Fe_8 and Mn_12 containing protons, too.",1006.4960v3
2010-08-12,Dynamical damping terms for symmetry-seeking shift conditions,"Suitable gauge conditions are fundamental for stable and accurate
numerical-relativity simulations of inspiralling compact binaries. A number of
well-studied conditions have been developed over the last decade for both the
lapse and the shift and these have been successfully used both in vacuum and
non-vacuum spacetimes when simulating binaries with comparable masses. At the
same time, recent evidence has emerged that the standard ""Gamma-driver"" shift
condition requires a careful and non-trivial tuning of its parameters to ensure
long-term stable evolutions of unequal-mass binaries. We present a novel gauge
condition in which the damping constant is promoted to be a dynamical variable
and the solution of an evolution equation. We show that this choice removes the
need for special tuning and provides a shift damping term which is free of
instabilities in our simulations and dynamically adapts to the individual
positions and masses of the binary black-hole system. Our gauge condition also
reduces the variations in the coordinate size of the apparent horizon of the
larger black hole and could therefore be useful when simulating binaries with
very small mass ratios.",1008.2212v2
2010-08-31,A SINFONI Integral Field Spectroscopy Survey for Galaxy Counterparts to Damped Lyman-alpha Systems - II. Dynamical Properties of the Galaxies towards Q0302-223 and Q1009-0026,"Details of processes through which galaxies convert their gas into stars need
to be studied in order to obtain a complete picture of galaxy formation. One
way to tackle these phenomena is to relate the HI gas and the stars in
galaxies. Here, we present dynamical properties of Damped and sub-Damped
Lyman-alpha Systems identified in H-alpha emission with VLT/SINFONI at near
infra-red wavelengths. While the DLA towards Q0302-223 is found to be
dispersion-dominated, the sub-DLA towards Q1009-0026 shows clear signatures of
rotation. We use a proxy to circular velocity to estimate the mass of the halo
in which the sub-DLA resides and find M_halo=10^12.6 M_sun. We also derive
dynamical masses of these objects, and find M_dyn=10^10.3 M_sun and 10^10.9
M_sun. For one of the two systems (towards Q0302-223), we are able to derive a
stellar mass of M_*=10^9.5 M_sun from Spectral Energy Distribution fit. The gas
fraction in this object is 1/3rd, comparable to similar objects at these
redshifts. Our work illustrates that detailed studies of quasar absorbers can
offer entirely new insights into our knowledge of the interaction between stars
and the interstellar gas in galaxies.",1009.0027v1
2010-11-10,"Standing Slow-Mode Waves in Hot Coronal Loops: Observations, Modeling, and Coronal Seismology","Strongly damped Doppler shift oscillations are observed frequently associated
with flarelike events in hot coronal loops. In this paper, a review of the
observed properties and the theoretical modeling is presented. Statistical
measurements of physical parameters (period, decay time, and amplitude) have
been obtained based on a large number of events observed by SOHO/SUMER and
Yohkoh/BCS. Several pieces of evidence are found to support their
interpretation in terms of the fundamental standing longitudinal slow mode. The
high excitation rate of these oscillations in small- or micro-flares suggest
that the slow mode waves are a natural response of the coronal plasma to
impulsive heating in closed magnetic structure. The strong damping and the
rapid excitation of the observed waves are two major aspects of the waves that
are poorly understood, and are the main subject of theoretical modeling. The
slow waves are found mainly damped by thermal conduction and viscosity in hot
coronal loops. The mode coupling seems to play an important role in rapid
excitation of the standing slow mode. Several seismology applications such as
determination of the magnetic field, temperature, and density in coronal loops
are demonstrated. Further, some open issues are discussed.",1011.2483v1
2010-11-29,Long-time dynamics of Kirchhoff wave models with strong nonlinear damping,"We study well-posedness and long-time dynamics of a class of quasilinear wave
equations with a strong damping. We accept the Kirchhoff hypotheses and assume
that the stiffness and damping coefficients are $C^1$ functions of the
$L_2$-norm of the gradient of the displacement. We first prove the existence
and uniqueness of weak solutions and study their properties for a rather wide
class of nonlinearities which covers the case of possible degeneration (or even
negativity) of the stiffness coefficient and the case of a supercritical source
term. Our main results deal with global attractors. In the case of strictly
positive stiffness factors we prove that in the natural energy space endowed
with a partially strong topology there exists a global attractor whose fractal
dimension is finite. In the non-supercritical case the partially strong
topology becomes strong and a finite dimensional attractor exists in the strong
topology of the energy space. Moreover, in this case we also establish the
existence of a fractal exponential attractor and give conditions that guarantee
the existence of a finite number of determining functionals. Our arguments
involve a recently developed method based on ""compensated"" compactness and
quasi-stability estimates.",1011.6271v3
2010-12-01,Dissipative processes in superfluid neutron stars,"We present some results about a novel damping mechanism of r-mode
oscillations in neutron stars due to processes that change the number of
protons, neutrons and electrons. Deviations from equilibrium of the number
densities of the various species lead to the appearance in the Euler equations
of the system of a dissipative mechanism, the so-called rocket effect. The
evolution of the r-mode oscillations of a rotating neutron star are influenced
by the rocket effect and we present estimates of the corresponding damping
timescales. In the description of the system we employ a two-fluid model, with
one fluid consisting of all the charged components locked together by the
electromagnetic interaction, while the second fluid consists of superfluid
neutrons. Both components can oscillate however the rocket effect can only
efficiently damp the countermoving r-mode oscillations, with the two fluids
oscillating out of phase. In our analysis we include the mutual friction
dissipative process between the neutron superfluid and the charged component.
We neglect the interaction between the two r-mode oscillations as well as
effects related with the crust of the star. Moreover, we use a simplified model
of neutron star assuming a uniform mass distribution.",1012.0345v1
2010-12-08,Nonequilibrium dynamics of the Holstein polaron driven by external electric field,"This work represents a fundamental study of a Holstein polaron in one
dimension driven away from the ground state by a constant electric field.
Taking fully into account quantum effects we follow the time-evolution of the
system from its ground state as the constant electric field is switched on at t
= 0, until it reaches a steady state. At weak electron phonon coupling (EP) the
system experiences damped Bloch oscillations (BO) characteristic for
noninteracting electron band. An analytic expression of the steady state
current is proposed in terms of weak EP coupling and large electric field. For
moderate values of EP coupling the oscillations are almost critically damped
and the system reaches the steady state after a short time. In the strong
coupling limit weakly damped BO, consistent with nearly adiabatic evolution
within the polaron band, persist up to extremely large electric fields. A
traveling polaron under the influence of the electric field leaves behind a
trail of phonon excitations absorbing the excess energy gained from the
electric field. The shape of the traveling polaron is investigated in details.",1012.1716v3
2011-01-19,Numerical simulation of fundamental trapped sausage modes,"Context: We integrate the 2D MHD ideal equations of a straight slab to
simulate observational results associated with fundamental sausage trapped
modes. Aims: Starting from a non-equilibrium state with a dense chromospheric
layer, we analyse the evolution of the internal plasma dynamics of magnetic
loops, subject to line-tying boundary conditions, and with the coronal
parameters described in Asai et al. (2001) and Melnikov et al. (2002) to
investigate the onset and damping of sausage modes. Methods: To integrate the
equations we used a high resolution shock-capturing (HRSC) method specially
designed to deal appropriately with flow discontinuities. Results: Due to
non-linearities and inhomogeneities, pure modes are difficult to sustain and
always occur coupled among them so as to satisfy, e.g., the line-tying
constraint. We found that, in one case, the resonant coupling of the sausage
fundamental mode with a slow one results in a non-dissipative damping of the
former. Conclusions: In scenarios of thick and dense loops, where the
analytical theory predicts the existence of fundamental trapped sausage modes,
the coupling of fast and slow quasi-periodic modes -with a node at the center
of the longitudinal speed- occur contributing to the damping of the fast mode.
If a discontinuity in the total pressure between the loop and the corona is
assumed, a fundamental fast sausage transitory leaky regime is spontaneously
produced and an external compressional Alfv\'en wave takes away the magnetic
energy.",1101.3782v1
2011-03-25,Dissipation and Vertical Energy Transport in Radiation-Dominated Accretion Disks,"Standard models of radiation supported accretion disks generally assume that
diffusive radiation flux is solely responsible for vertical heat transport.
This requires that heat must be generated at a critical rate per unit volume if
the disk is to be in hydrostatic and thermal equilibrium. This raises the
question of how heat is generated and how energy is transported in MHD
turbulence. By analysis of a number of radiation/MHD stratified shearing-box
simulations, we show that the divergence of the diffusive radiation flux is
indeed capped at the critical rate, but deep inside the disk, substantial
vertical energy flux is also carried by advection of radiation. Work done by
radiation pressure is a significant part of the energy budget, and much of this
work is dissipated later through damping by radiative diffusion. We show how
this damping can be measured in the simulations, and identify its physical
origins. Radiative damping accounts for as much as tens of percent of the total
dissipation, and is the only realistic physical mechanism for dissipation of
turbulence that can actually be resolved in numerical simulations of accretion
disks. Buoyancy associated with dynamo-driven, highly magnetized,
nearly-isobaric nonlinear slow magnetosonic fluctuations is responsible for the
radiation advection flux, and also explains the persistent periodic magnetic
upwelling seen at all values of the radiation to gas pressure ratio. The
intimate connection between radiation advection and magnetic buoyancy is the
first example we know of in astrophysics in which a dynamo has direct impact on
the global energetics of a system.",1103.5052v1
2011-06-09,Planet-disk interaction in highly inclined systems,"We study the interaction of a proto-planetary disk and a planet on a highly
inclined orbit in the linear regime. The evolution of the planet is dominated
by dynamical friction for planet masses above several Earth-masses. Smaller
planets are dominated by aerodynamic drag, especially for very high
inclinations and retrograde orbits.
  The time-scales associated with migration and inclination damping are
calculated. For certain values of the inclination, the inclination damping
time-scale is longer than the migration time-scale and the disk lifetime. This
result shows that highly inclined planets can not (re-)align with the
proto-planetary disk.
  We discuss the dependence of numerical simulations on the gravitational
softening parameter. We find only a logarithmic dependence, making global three
dimensional simulations of this process computationally feasible.
  A large fraction of Hot Jupiters is on highly inclined orbits with respect to
the rotation axis of the star. On the other hand small-mass planetary systems
discovered by the Kepler mission have low mutual inclinations. This shows that
there are two distinct formation mechanisms at work. The process that creates
inclined Hot Jupiters does not operate on small mass planets because the
damping timescales are so long that these systems would still be inclined
today.",1106.1869v2
2011-08-16,Brownian force noise from molecular collisions and the sensitivity of advanced gravitational wave observatories,"We present an analysis of Brownian force noise from residual gas damping of
reference test masses as a fundamental sensitivity limit in small force
experiments. The resulting acceleration noise increases significantly when the
distance of the test mass to the surrounding experimental apparatus is smaller
than the dimension of the test mass itself. For the Advanced LIGO
interferometric gravitational wave observatory, where the relevant test mass is
a suspended 340 mm diameter cylindrical end mirror, the force noise power is
increased by roughly a factor 40 by the presence of a similarly shaped reaction
mass at a nominal separation of 5 mm. The force noise, of order 20 fN\rthz\ for
$2 \times 10^{-6}$ Pa of residual H$_2$ gas, rivals quantum optical
fluctuations as the dominant noise source between 10 and 30 Hz. We present here
a numerical and analytical analysis for the gas damping force noise for
Advanced LIGO, backed up by experimental evidence from several recent
measurements. Finally, we discuss the impact of residual gas damping on the
gravitational wave sensitivity and possible mitigation strategies.",1108.3254v2
2011-09-22,Hole spin relaxation and coefficients in Landau-Lifshitz-Gilbert equation in ferromagnetic GaMnAs,"We investigate the temperature dependence of the coefficients in the
Landau-Lifshitz-Gilbert equation in ferromagnetic GaMnAs by employing the Zener
model. We first calculate the hole spin relaxation time based on the
microscopic kinetic equation. We find that the hole spin relaxation time is
typically several tens femtoseconds and can present a nonmonotonic temperature
dependence due to the variation of the interband spin mixing, influenced by the
temperature related Zeeman splitting. With the hole spin relaxation time, we
are able to calculate the coefficients in the Landau-Lifshitz-Gilbert equation,
such as the Gilbert damping, nonadiabatic spin torque, spin stiffness and
vertical spin stiffness coefficients. We find that the nonadiabatic spin torque
coefficient $\beta$ is around $0.1\sim 0.3$ at low temperature, which is
consistent with the experiment [Adam {\em et al.}, Phys. Rev. B {\bf 80},
193204 (2009)]. As the temperature increases, $\beta$ monotonically increases
and can exceed one in the vicinity of the Curie temperature. In the low
temperature regime with $\beta<1$, the Gilbert damping coefficient $\alpha$
increases with temperature, showing good agreement with the experiments [Sinova
{\em et al.}, Phys. Rev. B {\bf 69}, 085209 (2004); Khazen {\em et al.}, {\em
ibid.} {\bf 78}, 195210 (2008)]. Furthermore, we predict that $\alpha$
decreases with increasing temperature once $\beta>1$ near the Curie
temperature. We also find that the spin stiffness decreases with increasing
temperature, especially near the Curie temperature due to the modification of
the finite $\beta$. Similar to the Gilbert damping, the vertical spin stiffness
coefficient is also found to be nonmonotonically dependent on the temperature.",1109.4964v1
2011-09-23,Accretion of Rocky Planets by Hot Jupiters,"The observed population of Hot Jupiters displays a stunning variety of
physical properties, including a wide range of densities and core sizes for a
given planetary mass. Motivated by the observational sample, this paper studies
the accretion of rocky planets by Hot Jupiters, after the Jovian planets have
finished their principal migration epoch and become parked in $\sim4$-day
orbits. In this scenario, rocky planets form later and then migrate inward due
to torques from the remaining circumstellar disk, which also damps the orbital
eccentricity. This mechanism thus represents one possible channel for
increasing the core masses and metallicities of Hot Jupiters. This paper
determines probabilities for the possible end states for the rocky planet:
collisions with the Jovian planets, accretion onto the star, ejection from the
system, and long-term survival of both planets. These probabilities depend on
the mass of the Jovian planet and its starting orbital eccentricity, as well as
the eccentricity damping rate for the rocky planet. Since these systems are
highly chaotic, a large ensemble ($N\sim10^3$) of simulations with effectively
equivalent starting conditions is required. Planetary collisions are common
when the eccentricity damping rate is sufficiently low, but are rare otherwise.
For systems that experience planetary collisions, this work determines the
distributions of impact velocities -- both speeds and impact parameters -- for
the collisions. These velocity distributions help determine the consequences of
the impacts, e.g., where energy and heavy elements are deposited within the
giant planets.",1109.5104v1
2011-09-27,Dispersion and damping of zone-boundary magnons in the noncentrosymmetric superconductor CePt3Si,"Inelastic neutron scattering (INS) is employed to study damped spin-wave
excitations in the noncentrosymmetric heavy-fermion superconductor CePt3Si
along the antiferromagnetic Brillouin-zone boundary in the low-temperature
magnetically ordered state. Measurements along the (1/2 1/2 L) and (H H 1/2-H)
reciprocal-space directions reveal deviations in the spin-wave dispersion from
the previously reported model. Broad asymmetric shape of the peaks in energy
signifies strong spin-wave damping by interactions with the particle-hole
continuum. Their energy width exhibits no evident anomalies as a function of
momentum along the (1/2 1/2 L) direction, which could be attributed to
Fermi-surface nesting effects, implying the absence of pronounced commensurate
nesting vectors at the magnetic zone boundary. In agreement with a previous
study, we find no signatures of the superconducting transition in the magnetic
excitation spectrum, such as a magnetic resonant mode or a superconducting spin
gap, either at the magnetic ordering wavevector (0 0 1/2) or at the zone
boundary. However, the low superconducting transition temperature in this
material still leaves the possibility of such features being weak and therefore
hidden below the incoherent background at energies ~0.1 meV, precluding their
detection by INS.",1109.5784v1
2011-12-16,Nonlinear viscous damping and gravitational wave detectability of the f-mode instability in neutron stars,"We study the damping of the gravitational radiation-driven f-mode instability
in rotating neutron stars by nonlinear bulk viscosity in the so-called
supra-thermal regime. In this regime the dissipative action of bulk viscosity
is known to be enhanced as a result of nonlinear contributions with respect to
the oscillation amplitude. Our analysis of the f-mode instability is based on a
time-domain code that evolves linear perturbations of rapidly rotating
polytropic neutron star models. The extracted mode frequency and eigenfunctions
are subsequently used in standard energy integrals for the gravitational wave
growth and viscous damping. We find that nonlinear bulk viscosity has a
moderate impact on the size of the f-mode instability window, becoming an
important factor and saturating the mode's growth at a relatively large
oscillation amplitude. We show similarly that nonlinear bulk viscosity leads to
a rather high saturation amplitude even for the r-mode instability. In
addition, we show that the action of bulk viscosity can be significantly
mitigated by the presence of superfluidity in neutron star matter. Apart from
revising the f-mode's instability window we provide results on the mode's
gravitational wave detectability. Considering an f-mode-unstable neutron star
located in the Virgo cluster and assuming a mode amplitude at the level allowed
by bulk viscosity, we find that the emitted gravitational wave signal could be
detectable by advanced ground-based detectors such as Advanced LIGO/Virgo and
the Einstein Telescope.",1112.3931v2
2012-02-28,Planetesimal Dynamics in Inclined Binary Systems: The Role of Gas-Disk Gravity,"We investigate the effects of gas-disk gravity on the planetesimal dynamics
in inclined binary systems, where the circumprimary disk plane is tilted by a
significant angle ($i_B$) with respect to the binary disk plane. Our focus is
on the Lidov-Kozai mechanism and the evolution of planetesimal eccentricity and
inclination. Using both analytical and numerical methods, we find that, on one
hand, the disk gravity generally narrows down the Kozai-on region, i.e., the
Lidov-Kozai effect can be suppressed in certain parts of (or even the whole of)
the disk, depending on various parameters. In the Kozai-off region,
planetesimals would move on orbits close to the mid-plane of gas-disk, with the
relative angle ($i^{'}$) following a small amplitude periodical oscillation. On
the other hand, when we include the effects of disk gravity, we find that the
Lidov-Kozai effect can operate even at arbitrarily low inclinations ($i_B$),
although lower $i_B$ leads to a smaller Kozai-on region. Furthermore, in the
Kozai-on region, most planetesimals' eccentricities can be excited to extremely
high values ($\sim 1$), and such extreme high eccentricities usually accompany
orbital flipping, i.e., planetesimal orbit flips back and forth between
anterograde and retrograde. Once a planetesimal reaches very high orbital
eccentricity, gas drag damping will shrink the planetesimal orbit, forming a
""hot planetesimal"" on a near circular orbit very close to the primary star.
Such a mechanism, if replacing the planetesimals and gas drag damping with
Jupiters and tidal damping respectively, may lead to frequent production of
hot-Jupiters.",1202.6102v1
2012-06-04,In search of random uncorrelated particle motion (RUM) in a simple random flow field,"DNS studies of dispersed particle motion in isotropic homogeneous turbulence
[1] have revealed the existence of a component of random uncorrelated motion
(RUM)dependent on the particle inertia {\tau}p(normalised particle response
time or Stoke number). This paper reports the presence of RUM in a simple
linear random smoothly varying flow field of counter rotating vortices where
the two-particle velocity correlation was measured as a function of spatial
separation. Values of the correlation less than one for zero separation
indicated the presence of RUM. In terms of Stokes number, the motion of the
particles in one direction corresponds to either a heavily damped ({\tau}p <
0.25) or lightly damped ({\tau}p > 0.25)harmonic oscillator. In the lightly
damped case the particles overshoot the stagnation lines of the flow and are
projected from one vortex to another (the so-called sling-shot effect). It is
shown that RUM occurs only when {\tau}p > 0.25, increasing monotonically with
increasing Stokes number. Calculations of the particle pair separation
distribution function show that equilibrium of the particle concentration field
is never reached, the concentration at zero separation increasing monotonically
with time. This is consistent with the calculated negative values of the
average Liapounov exponent (finite compressibility) of the particle velocity
field.",1206.0572v1
2012-06-11,Solitons in a parametrically driven damped discrete nonlinear Schrödinger equation,"We consider a parametrically driven damped discrete nonlinear Schr\""odinger
(PDDNLS) equation. Analytical and numerical calculations are performed to
determine the existence and stability of fundamental discrete bright solitons.
We show that there are two types of onsite discrete soliton, namely onsite type
I and II. We also show that there are four types of intersite discrete soliton,
called intersite type I, II, III, and IV, where the last two types are
essentially the same, due to symmetry. Onsite and intersite type I solitons,
which can be unstable in the case of no dissipation, are found to be stabilized
by the damping, whereas the other types are always unstable. Our further
analysis demonstrates that saddle-node and pitchfork (symmetry-breaking)
bifurcations can occur. More interestingly, the onsite type I, intersite type
I, and intersite type III-IV admit Hopf bifurcations from which emerge periodic
solitons (limit cycles). The continuation of the limit cycles as well as the
stability of the periodic solitons are computed through the numerical
continuation software Matcont. We observe subcritical Hopf bifurcations along
the existence curve of the onsite type I and intersite type III-IV. Along the
existence curve of the intersite type I we observe both supercritical and
subcritical Hopf bifurcations.",1206.2405v1
2012-07-13,Axion as a cold dark matter candidate: low-mass case,"Axion as a coherently oscillating scalar field is known to behave as a cold
dark matter in all cosmologically relevant scales. For conventional axion mass
with 10^{-5} eV, the axion reveals a characteristic damping behavior in the
evolution of density perturbations on scales smaller than the solar system
size. The damping scale is inversely proportional to the square-root of the
axion mass. We show that the axion mass smaller than 10^{-24} eV induces a
significant damping in the baryonic density power spectrum in cosmologically
relevant scales, thus deviating from the cold dark matter in the scale smaller
than the axion Jeans scale. With such a small mass, however, our basic
assumption about the coherently oscillating scalar field is broken in the early
universe. This problem is shared by other dark matter models based on the
Bose-Einstein condensate and the ultra-light scalar field. We introduce a
simple model to avoid this problem by introducing evolving axion mass in the
early universe, and present observational effects of present-day low-mass axion
on the baryon density power spectrum, the cosmic microwave background radiation
(CMB) temperature power spectrum, and the growth rate of baryon density
perturbation. In our low-mass axion model we have a characteristic small-scale
cutoff in the baryon density power spectrum below the axion Jeans scale. The
small-scale deviations from the cold dark matter model in both matter and CMB
power spectra clearly differ from the ones expected in the cold dark matter
model mixed with the massive neutrinos as a hot dark matter component.",1207.3124v1
2012-09-04,Solving Vlasov Equations Using NRxx Method,"In this paper, we propose a moment method to numerically solve the Vlasov
equations using the framework of the NRxx method developed in [6, 8, 7] for the
Boltzmann equation. Due to the same convection term of the Boltzmann equation
and the Vlasov equation, it is very convenient to use the moment expansion in
the NRxx method to approximate the distribution function in the Vlasov
equations. The moment closure recently presented in [5] is applied to achieve
the globally hyperbolicity so that the local well-posedness of the moment
system is attained. This makes our simulations using high order moment
expansion accessible in the case of the distribution far away from the
equilibrium which appears very often in the solution of the Vlasov equations.
With the moment expansion of the distribution function, the acceleration in the
velocity space results in an ordinary differential system of the macroscopic
velocity, thus is easy to be handled. The numerical method we developed can
keep both the mass and the momentum conserved. We carry out the simulations of
both the Vlasov-Poisson equations and the Vlasov-Poisson-BGK equations to study
the linear Landau damping. The numerical convergence is exhibited in terms of
the moment number and the spatial grid size, respectively. The variation of
discretized energy as well as the dependence of the recurrence time on moment
order is investigated. The linear Landau damping is well captured for different
wave numbers and collision frequencies. We find that the Landau damping rate
linearly and monotonically converges in the spatial grid size. The results are
in perfect agreement with the theoretic data in the collisionless case.",1209.0527v1
2012-10-09,A close-pair analysis of damp mergers at intermediate redshifts,"We have studied the kinematics of ~2800 candidate close pair galaxies at
0.1<z<1.2 identified from the Canada-France-Hawaii Telescope Legacy Survey
fields. Spectra of these systems were obtained using spectrometers on the 6.5m
Magellan and 5m Hale telescopes. These data allow us to constrain the rate of
dry mergers at intermediate redshifts and to test the `hot halo' model for
quenching of star formation. Using virial radii estimated from the correlation
between dynamical and stellar masses published by Leauthaud et al. (2011), we
find that around 1/5 of our candidate pairs are likely to share a common dark
matter halo (our metric for close physical association). These pairs are
divided into red-red, blue-red and blue-blue systems using the rest-frame
colors classification method introduced in Chou et al. (2011). Galaxies
classified as red in our sample have very low star-formation rates, but they
need not be totally quiescent, and hence we refer to them as `damp', rather
than `dry', systems. After correcting for known selection effects, the fraction
of blue-blue pairs is significantly greater than that of red-red and blue-red
pairs. Red-red pairs are almost entirely absent from our sample, suggesting
that damp mergers are rare at z~0.5. Our data supports models with a short
merging timescale (<0.5 Gyr) in which star-formation is enhanced in the early
phase of mergers, but quenched in the late phase. Hot halo models may explain
this behaviour, but only if virial shocks that heat gas are inefficient until
major mergers are nearly complete.",1210.2692v1
2012-10-24,Dual Trigger of Transverse Oscillations in a Prominence by EUV Fast and Slow Coronal Waves: SDO/AIA and STEREO/EUVI Observations,"We analyze flare-associated transverse oscillations in a quiescent solar
prominence on 8-9 September, 2010. Both the flaring active region and the
prominence were located near the West limb, with a favorable configuration and
viewing angle. The fulldisk extreme ultraviolet (EUV) images of the Sun
obtained with high spatial and temporal resolution by the Atmospheric Imaging
Assembly (AIA) aboard the Solar Dynamics Observatory, show flare-associated
lateral oscillations of the prominence sheet. The STEREO-A spacecraft, 81.5
degrees ahead of the Sun-Earth line, provides on-disk view of the
flare-associated coronal disturbances. We derive the temporal profile of the
lateral displacement of the prominence sheet by using the image
cross-correlation technique. The displacement curve was de-trended and the
residual oscillatory pattern was derived. We fit these oscillations with a
damped cosine function with a variable period and find that the period is
increasing. The initial oscillation period (P0) is 28.2 minutes and the damping
time (t_D) of 44 minutes. We confirm the presence of fast and slow EUV wave
components. Using STEREO-A observations we derive a propagation speed of 250
km/s for the slow EUV wave by applying time-slice technique to the running
difference images. We propose that the prominence oscillations are excited by
the fast EUV wave while the increase in oscillation period of the prominence is
an apparent effect, related to a phase change due to the slow EUV wave acting
as a secondary trigger. We discuss implications of the dual trigger effect for
coronal prominence seismology and scaling law studies of damping mechanisms.",1210.6690v1
2012-10-25,Molecular dissipation in the nonlinear eddy viscosity in the Navier-Stokes equations: modelling of accretion discs,"Physical damping, regarding the nonlinear Navier-Stokes viscous flow
dynamics, refers to a tensorial turbulent dissipation term, attributed to
adjacent moving macroscopic flow components. Mutual dissipation among these
parts of fluid is described by a braking term in the momentum equation together
with a heating term in the energy equation, both responsible of the damping of
the momentum variation and of the viscous conversion of mechanical energy into
heat. A macroscopic mixing scale length is currently the only characteristic
length needed in the nonlinear modelling of viscous fluid dynamics describing
the nonlinear eddy viscosity through the kinematic viscosity coefficient in the
viscous stress tensor, without any reference to the chemical composition and to
the atomic dimensions. Therefore, in this paper, we write a new formulation for
the kinematic viscosity coefficient to the turbulent viscous physical
dissipation in the Navier-Stokes equations, where molecular parameters are also
included. Results of 2D tests are shown, where comparisons among flow
structures are made on 2D shockless radial viscous transport and on 2D damping
of collisional chaotic turbulence. An application to the 3D accretion disc
modelling in low mass cataclysmic variables is also discussed. Consequences of
the kinematic viscosity coefficient reformulation in a more strictly physical
terms on the thermal conductivity coefficient for dilute gases are also
discussed. The physical nature of the discussion here reported excludes any
dependence by the pure mathematical aspect of the numerical modelling.",1210.6848v3
2012-11-07,Gaussification through decoherence,"We investigate the loss of nonclassicality and non-Gaussianity of a
single-mode state of the radiation field in contact with a thermal reservoir.
The damped density matrix for a Fock-diagonal input is written using the Weyl
expansion of the density operator. Analysis of the evolution of the
quasiprobability densities reveals the existence of two successive
characteristic times of the reservoir which are sufficient to assure the
positivity of the Wigner function and, respectively, of the $P$ representation.
We examine the time evolution of non-Gaussianity using three recently
introduced distance-type measures. They are based on the Hilbert-Schmidt
metric, the relative entropy, and the Bures metric. Specifically, for an
$M$-photon-added thermal state, we obtain a compact analytic formula of the
time-dependent density matrix that is used to evaluate and compare the three
non-Gaussianity measures. We find a good consistency of these measures on the
sets of damped states. The explicit damped quasiprobability densities are shown
to support our general findings regarding the loss of negativities of Wigner
and $P$ functions during decoherence. Finally, we point out that Gaussification
of the attenuated field mode is accompanied by a nonmonotonic evolution of the
von Neumann entropy of its state conditioned by the initial value of the mean
photon number.",1211.1701v3
2012-11-14,New algorithm for footstep localization using seismic sensors in an indoor environment,"In this study, we consider the use of seismic sensors for footstep
localization in indoor environments. A popular strategy of localization is to
use the measured differences in arrival times of source signals at multiple
pairs of receivers. In the literature, most algorithms that are based on time
differences of arrival (TDOA) assume that the propagation velocity is a
constant as a function of the source position, which is valid for air
propagation or even for narrow band signals. However a bounded medium such as a
concrete slab (encountered in indoor environement) is usually dispersive and
damped. In this study, we demonstrate that under such conditions, the concrete
slab can be assimilated to a thin plate; considering a Kelvin-Voigt damping
model, we introduce the notion of {\em perceived propagation velocity}, which
decreases when the source-sensor distance increases. This peculiar behaviour
precludes any possibility to rely on existing localization methods in indoor
environment. Therefore, a new localization algorithm that is adapted to a
damped and dispersive medium is proposed, using only on the sign of the
measured TDOA (SO-TDOA). A simulation and some experimental results are
included, to define the performance of this SO-TDOA algorithm.",1211.3233v2
2013-02-05,Complex fragment emission in low energy light-ion reactions,"Inclusive energy spectra of the complex fragments (3 $\leq$ Z $\leq$ 5)
emitted in the reactions $^{12}$C (77 MeV)+ $^{28}$Si, $^{11}$B (64 MeV)+
$^{28}$Si and $^{12}$C (73 MeV)+ $^{27}$Al (all having the same excitation
energy of $ \sim$ 67 MeV), have been measured in the angular range of
10$^\circ$ $\lesssim \theta_{lab} \lesssim$ 60$^\circ$. The fully energy damped
(fusion-fission) and the partially energy damped (deep inelastic) components of
the fragment energy spectra have been extracted. It has been found that the
yields of the fully energy damped fragments for all the above reactions are in
conformity with the respective statistical model predictions. The time scales
of various deep inelastic fragment emissions have been extracted from the
angular distribution data. The angular momentum dissipation in deep inelastic
collisions has been estimated from the data and it has been found to be close
to the corresponding sticking limit value.",1302.1002v1
2013-02-11,Propagation of Alfvénic Waves From Corona to Chromosphere and Consequences for Solar Flares,"How do magnetohydrodynamic waves travel from the fully ionized corona, into
and through the underlying partially ionized chromosphere, and what are the
consequences for solar flares? To address these questions, we have developed a
2-fluid model (of plasma and neutrals) and used it to perform 1D simulations of
Alfv\'en waves in a solar atmosphere with realistic density and temperature
structure. Studies of a range of solar features (faculae, plage, penumbra and
umbra) show that energy transmission from corona to chromosphere can exceed 20%
of incident energy for wave periods of one second or less. Damping of waves in
the chromosphere depends strongly on wave frequency: waves with periods 10
seconds or longer pass through the chromosphere with relatively little damping,
however, for periods of 1 second or less, a substantial fraction (37%-100%) of
wave energy entering the chromosphere is damped by ion-neutral friction in the
mid and upper chromosphere, with electron resistivity playing some role in the
lower chromosphere and in umbras. We therefore conclude that Alfv\'enic waves
with periods of a few seconds or less are capable of heating the chromosphere
during solar flares, and speculate that they could also contribute to electron
acceleration or exciting sunquakes.",1302.2458v1
2013-02-25,Non-classical Correlations in the Quantum Search Algorithm,"Entanglement lies at the heart of quantum mechanics and has no classical
analogue. It is central to the speed up achieved by quantum algorithms over
their classical counterparts. The Grover's search algorithm is one such
algorithm which enables us to achieve a quadratic speed up over any known
classical algorithm that searches for an element in an unstructured database.
Here, we analyse and quantify the effects of entanglement in the generalized
version of this algorithm for two qubits. By 'generalized', it is meant that
the use of any arbitrary single qubit unitary gate is permitted to create
superposed states. Our analysis has been firstly on a noise free environment
and secondly in the presence of noise. In the absence of noise, we establish a
relation between the concurrence and the amplitude of the final state thereby
showing the explicit effects of entanglement on the same. Moreover, the effects
of noisy channels, namely amplitude and phase damping channels are studied. We
investigate the amount of quantum correlation in the states obtained after the
phase inversion stage of the algorithm followed by interaction of those states
with the noisy environment. The quantum correlations are quantified by
geometric discord. It has been revealed that the states generated after the
effect of amplitude damping on the phase inverted states of the quantum search
algorithm possess non-zero quantum correlation even when entanglement is
absent. However, this is absent in the phase damping scenario.",1302.6005v1
2013-03-01,Generation of Electrostatic Waves via Parametric Instability and Heating of Solar Corona,"In the upper layers of the solar atmosphere the temperature increases
sharply. We studied possibility of the transfer of neutrals motion energy into
the electrostatic waves.Electrostatic waves could damp in the upper layers of
the solar atmosphere and their energy could be transformed into the thermal
energy of the solar atmosphere plasma. When studying the plasma dynamics in the
low altitudes of the solar atmosphere, we investigated hydrodynamics of the
plasma which consists of thee components-electrons, ions and neutrals. In order
to study evolution of disturbances of high amplitudes the parametric resonance
technique is used. The dispersion relation for the electrostatic waves excited
due tot he motion of neutrals is derived. The frequencies of electromagnetic
waves which could be excited due to existence of the acoustic wave are found.
The increment of excited electrostatic waves are determined. The motion of the
neutrals in the lower solar atmosphere, where ionization rate is low, could
excite electrostatic waves. In the upper solar atmosphere the ionization rate
increases and motion of the neutrals could not support electrostatic waves and
these waves could damp due to the collision of the charged particles. The
energy of the damping waves could be transformed into the thermal energy of the
plasma in the upper atmosphere.",1303.0151v1
2013-03-19,Cosmic Ray Streaming in Clusters of Galaxies,"The observed bimodality in radio luminosity in galaxy clusters is puzzling.
We investigate the possibility that cosmic-ray (CR) streaming in the
intra-cluster medium can 'switch off' hadronically induced radio and gamma-ray
emission. For self-confined CRs, this depends on the source of MHD wave
damping: if only non-linear Landau damping operates, then CRs stream on the
slow Alfvenic timescale, but if turbulent wave damping operates, super-Alfvenic
streaming is possible. As turbulence increases, it promotes outward streaming
more than it enables inward turbulent advection. Curiously, the CR flux is
independent of $\nabla f$ (as long as it is non-zero) and depends only on
plasma parameters; this enables radio halos with flat inferred CR profiles to
turn off. We perform 1D time-dependent calculations of a radio mini-halo
(Perseus) and giant radio halo (Coma) and find that both diminish in radio
luminosity by an order of magnitude in several hundred Myr, given plausible
estimates for the magnetic field in the outskirts of the cluster. Due to the
energy dependence of CR streaming, spectral curvature develops, and radio halos
turn off more slowly at low frequencies -- properties consistent with
observations. Similarly, CR streaming rapidly turns off gamma-ray emission at
the high-energies probed by Cherenkov telescopes, but not at the low energies
probed by Fermi. CR mediated wave-heating of the ICM is unaffected, as it is
dominated by ~GeV CRs which stream Alfvenically.",1303.4746v1
2013-05-13,New features of ion acoustic waves in inhomogeneous and permeating plasmas,"It is generally accepted that the ion acoustic (IA) wave in plasmas
containing ions and electrons with the same temperature is of minor importance
due to strong damping of the wave by hot resonant ions. In this work it will be
shown that the IA wave is susceptible to excitation even in plasmas with hot
ions when both an electromagnetic transverse wave and a background density
gradient are present in the plasma, and in addition the wave is in fact
unstable (i.e., growing) in the case of permeating homogeneous plasmas. The
multi-component fluid theory is used to describe the IA wave susceptibility for
excitation in inhomogeneous plasmas and its coupling with electromagnetic
waves. The growing IA wave in permeating homogeneous plasmas is described by
the kinetic theory. In plasmas with density and temperature gradients the IA
wave is effectively coupled with the electromagnetic waves. In comparison to
ordinary IA wave in homogeneous plasma, the Landau damping of the present wave
is much smaller, and to demonstrate this effect a simple but accurate fluid
model is presented for the Landau damping. In the case of permeating plasmas, a
kinetic mechanism for the current-less IA wave instability is presented, with a
very low threshold for excitation as compared with ordinary
electron-current-driven kinetic instability. Such growing IA waves can
effectively heat plasma in the upper solar atmosphere by a stochastic heating
mechanism presented in the work. The results of this work suggest that the IA
wave role in the heating of the solar atmosphere (chromosphere and corona)
should be reexamined.",1305.2739v1
2013-05-15,Beam energy dependence of the viscous damping of anisotropic flow,"The flow harmonics $v_{2,3}$ for charged hadrons, are studied for a broad
range of centrality selections and beam collision energies in Au+Au
($\sqrt{s_{NN}}= 7.7 - 200$ GeV) and Pb+Pb ($\sqrt{s_{NN}}= 2.76$ TeV)
collisions. They validate the characteristic signature expected for the system
size dependence of viscous damping at each collision energy studied. The
extracted viscous coefficients, that encode the magnitude of the ratio of shear
viscosity to entropy density $\eta/s$, are observed to decrease to an apparent
minimum as the collision energy is increased from $\sqrt{s_{NN}}= 7.7$ to
approximately 62.4 GeV; thereafter, they show a slow increase with
$\sqrt{s_{NN}}$ up to 2.76 TeV. This pattern of viscous damping provides the
first experimental constraint for $\eta/s$ in the temperature-baryon chemical
potential ($T, \mu_B$) plane, and could be an initial indication for decay
trajectories which lie close to the critical end point in the phase diagram for
nuclear matter.",1305.3341v3
2013-07-19,Exact 3D solution for static and damped harmonic response of simply supported general laminates,"The state-space method is adapted to obtain three dimensional exact solutions
for the static and damped dynamic behaviors of simply supported general
laminates. The state-space method is written in a general form that permits to
handle both cross-ply and antisymmetric angle-ply laminates. This general form
also permits to obtain exact solutions for general laminates, albeit with some
constraints. For the general case and for the static behavior, either an
additive term is added to the load to simulate simply supported boundary
conditions, or the plate bends in a particular way. For the dynamic behavior,
the general case leads to pairs of natural frequencies for each order, with
associated mode shapes. Finite element simulations have been performed to
validate most of the results presented in this study. As the boundary
conditions needed for the general case are not so straightforward, a specific
discussion has been added. It is shown that these boundary conditions also work
for the two aforementioned laminate classes. The damped harmonic response of a
non symmetrical isotropic sandwich is studied for different frequencies around
the fundamental frequency. The static and undamped dynamic behaviors of the
[-15/15], [0/30/0] and [-10/0/40] laminates are studied for various
length-to-thickness ratios.",1307.5285v2
2013-07-25,Lyman-alpha Heating of Inhomogeneous High-redshift Intergalactic Medium,"The intergalactic medium (IGM) prior to the epoch of reionization consists
mostly of neutral hydrogen gas. Ly-alpha photons produced by early stars
resonantly scatter off hydrogen atoms, causing energy exchange between the
radiation field and the gas. This interaction results in moderate heating of
the gas due to the recoil of the atoms upon scattering, which is of great
interest for future studies of the pre-reionization IGM in the HI 21 cm line.
We investigate the effect of this Ly-alpha heating in the IGM with linear
density, temperature, and velocity perturbations. Perturbations smaller than
the diffusion length of photons could be damped due to heat conduction by
Ly-alpha photons. The scale at which damping occurs and the strength of this
effect depend on various properties of the gas, the flux of Ly-alpha photons
and the way in which photon frequencies are redistributed upon scattering. To
find the relevant length scale and the extent to which Ly-alpha heating affects
perturbations, we calculate the gas heating rates by numerically solving
linearized Boltzmann equations in which scattering is treated by the
Fokker-Planck approximation. We find that (1) perturbations add a small
correction to the gas heating rate, and (2) the damping of temperature
perturbations occurs at scales with comoving wavenumber k>10^4 Mpc^{-1}, which
are much smaller than the Jeans scale and thus unlikely to substantially affect
the observed 21 cm signal.",1307.6859v2
2013-11-12,Investigation into electron cloud effects in the International Linear Collider positron damping ring,"We report modeling results for electron cloud buildup and instability in the
International Linear Collider positron damping ring. Updated optics, wiggler
magnets, and vacuum chamber designs have recently been developed for the 5 GeV,
3.2-km racetrack layout. An analysis of the synchrotron radiation profile
around the ring has been performed, including the effects of diffuse and
specular photon scattering on the interior surfaces of the vacuum chamber. The
results provide input to the cloud buildup simulations for the various magnetic
field regions of the ring. The modeled cloud densities thus obtained are used
in the instability threshold calculations. We conclude that the mitigation
techniques employed in this model will suffice to allow operation of the
damping ring at the design operational specifications.",1311.2890v4
2013-12-18,The behavior of transverse waves in nonuniform solar flux tubes. II. Implications for coronal loop seismology,"Seismology of coronal loops using observations of damped transverse
oscillations in combination with results from theoretical models is a tool to
indirectly infer physical parameters in the solar atmospheric plasma. Existing
seismology schemes based on approximations to the period and damping time of
kink oscillations are often used beyond their theoretical range of
applicability. These approximations assume that the variation of density across
the loop is confined to a nonuniform layer much thinner than the radius of the
loop, but the results of the inversion problem often do not satisfy this
preliminary hypothesis. Here, we determine the accuracy of the analytic
approximations to the period and damping time, and its impact on seismology
estimates, when largely nonuniform loops are considered. We find that the
accuracy of the approximations when used beyond their range of applicability is
strongly affected by the form of the density profile across the loop, that is
observationally unknown and so must be arbitrarily imposed as part of the
theoretical model. The error associated with the analytic approximations can be
larger than 50% even for relatively thin nonuniform layers. This error directly
affects the accuracy of approximate seismology estimates compared to actual
numerical inversions. In addition, assuming different density profiles can
produce noncoincident intervals of the seismic variables in inversions of the
same event. The ignorance about the true shape of density variation across the
loop is an important source of error that may dispute the reliability of
parameters seismically inferred assuming an ad hoc density profile.",1312.5079v1
2014-01-02,Quasi-Normal Modes for Subtracted Rotating and Magnetised Geometries,"We obtain explicit separable solutions of the wave equation of massless
minimally coupled scalar fields in the subtracted geometry of four-dimensional
rotating and Melvin (magnetised) four-charge black holes of the STU model, a
consistent truncation of maximally supersymmetric supergravity with four types
of electromagnetic fields. These backgrounds possess a hidden SL(2,R) x SL(2,R)
x SO(3) symmetry and faithfully model the near horizon geometry of these black
holes, but locate them in a confining asymptotically conical box. For each
subtracted geometry we obtain two branches of quasi-normal modes, given in
terms of hypergeometric functions and spherical harmonics. One branch is
over-damped and the other under-damped and they exhibit rotational splitting.
No black hole bomb is possible because the Killing field which co-rotates with
the horizon is everywhere timelike outside the black hole. A five-dimensional
lift of these geometries is given locally by the product of a BTZ black hole
with a two-sphere. This allows an explicit analysis of the minimally coupled
massive five-dimensional scalar field. Again, there are two branches, both
damped, however now their oscillatory parts are shifted by the quantised wave
number $k$ along the fifth circle direction.",1401.0544v3
2014-04-11,Functional Regression for Quasar Spectra,"The Lyman-alpha forest is a portion of the observed light spectrum of distant
galactic nuclei which allows us to probe remote regions of the Universe that
are otherwise inaccessible. The observed Lyman-alpha forest of a quasar light
spectrum can be modeled as a noisy realization of a smooth curve that is
affected by a `damping effect' which occurs whenever the light emitted by the
quasar travels through regions of the Universe with higher matter
concentration. To decode the information conveyed by the Lyman-alpha forest
about the matter distribution, we must be able to separate the smooth
`continuum' from the noise and the contribution of the damping effect in the
quasar light spectra. To predict the continuum in the Lyman-alpha forest, we
use a nonparametric functional regression model in which both the response and
the predictor variable (the smooth part of the damping-free portion of the
spectrum) are function-valued random variables. We demonstrate that the
proposed method accurately predicts the unobservable continuum in the
Lyman-alpha forest both on simulated spectra and real spectra. Also, we
introduce distribution-free prediction bands for the nonparametric functional
regression model that have finite sample guarantees. These prediction bands,
together with bootstrap-based confidence bands for the projection of the mean
continuum on a fixed number of principal components, allow us to assess the
degree of uncertainty in the model predictions.",1404.3168v1
2014-07-02,Spin Waves in Ferromagnetic Insulators Coupled via a Normal Metal,"Herein, we study the spin-wave dispersion and dissipation in a ferromagnetic
insulator--normal metal--ferromagnetic insulator system. Long-range dynamic
coupling because of spin pumping and spin transfer lead to collective magnetic
excitations in the two thin-film ferromagnets. In addition, the dynamic dipolar
field contributes to the interlayer coupling. By solving the
Landau-Lifshitz-Gilbert-Slonczewski equation for macrospin excitations and the
exchange-dipole volume as well as surface spin waves, we compute the effect of
the dynamic coupling on the resonance frequencies and linewidths of the various
modes. The long-wavelength modes may couple acoustically or optically. In the
absence of spin-memory loss in the normal metal, the spin-pumping-induced
Gilbert damping enhancement of the acoustic mode vanishes, whereas the optical
mode acquires a significant Gilbert damping enhancement, comparable to that of
a system attached to a perfect spin sink. The dynamic coupling is reduced for
short-wavelength spin waves, and there is no synchronization. For intermediate
wavelengths, the coupling can be increased by the dipolar field such that the
modes in the two ferromagnetic insulators can couple despite possible small
frequency asymmetries. The surface waves induced by an easy-axis surface
anisotropy exhibit much greater Gilbert damping enhancement. These modes also
may acoustically or optically couple, but they are unaffected by thickness
asymmetries.",1407.0635v1
2014-07-15,C$ν$B damping of primordial gravitational waves and the fine-tuning of the C$γ$B temperature anisotropy,"Damping of primordial gravitational waves due to the anisotropic stress
contribution owing to the cosmological neutrino background (C$\nu$B) is
investigated in the context of a radiation-to-matter dominated Universe.
Besides its inherent effects on the gravitational wave propagation, the
inclusion of the C$\nu$B anisotropic stress into the dynamical equations also
affects the tensor mode contribution to the anisotropy of the cosmological
microwave background (C$\gamma$B) temperature. Given that the fluctuations of
the C$\nu$B temperature in the (ultra)relativistic regime are driven by a
multipole expansion, the mutual effects on the gravitational waves and on the
C$\gamma$B are obtained through a unified prescription for a
radiation-to-matter dominated scenario. The results are confronted with some
preliminary results for the radiation dominated scenario. Both scenarios are
supported by a simplified analytical framework, in terms of a scale independent
dynamical variable, $k \eta$, that relates cosmological scales, $k$, and the
conformal time, $\eta$. The background relativistic (hot dark) matter
essentially works as an effective dispersive medium for the gravitational waves
such that the damping effect is intensified for the Universe evolving to the
matter dominated era. Changes on the temperature variance owing to the
inclusion of neutrino collision terms into the dynamical equations result into
spectral features that ratify that the multipole expansion coefficients
$C_{l}^{T}$'s die out for $l \sim 100$.",1407.4058v1
2014-08-08,Stable Magnetic Droplet Solitons in Spin Transfer Nanocontacts,"Magnetic thin films with perpendicular magnetic anisotropy (PMA) have
localized excitations that correspond to reversed dynamically precessing
magnetic moments, known as magnetic droplet solitons. Fundamentally, these
excitations are associated with an attractive interaction between elementary
spin-excitations (i.e., magnons) and were predicted to occur in PMA materials
in the absence of damping [1,2]. While damping, present in all magnetic
materials, suppresses these excitations, it is now possible to compensate
damping by spin transfer torques through electrical current flow in nanometer
scale contacts to ferromagnetic thin films [3,4]. A theory predicts the
appearance of magnetic droplet solitons at a threshold current in nanocontacts
[5] and, recently, experimental signatures of droplet nucleation have been
reported [6]. However, thus far, they have been observed to be nearly
reversible excitations, with only partially reversed magnetization and to be
subject to instabilities that cause them to drift away from the nanocontacts
(i.e., drift instabilities) [6]. Here we show that magnetic droplet solitons
can be stabilized in a spin transfer nanocontact. Further, they exhibit a
strong hysteretic response to fields and currents and a nearly fully reversed
magnetization in the contact. These observations, in addition to their
fundamental interest, open up new applications for magnetic droplet solitons as
multi-state high frequency current and field tunable oscillators.",1408.1902v1
2014-08-19,Probing Electron Interactions in a Two-Dimensional System by Quantum Magneto-Oscillations,"We have experimentally studied the renormalized effective mass m* and Dingle
temperature T_D in two spin subbands with essentially different electron
populations. Firstly, we found that the product (m*T_D) that determines damping
of quantum oscillations, to the first approximation, is the same in the
majority and minority subbands even at the spin polarization degree as high as
66\%. This result confirms the theoretical predictions that the interaction
takes place at high energies ~ E_F rather than within a narrow strip of
energies E_F\pm k_BT. Secondly, to the next approximation, we revealed a
difference in the damping factor of the two spin subbands, which causes
skewness of the oscillation lineshape. In the absence of the in-plane magnetic
field, the damping factor (m*T_D) is systematically smaller in the
spin-majority subband. The difference, quantified with the skew factor \gamma =
(T_{D\downarrow}-T_{D\uparrow})/2T_{D0} can be as large as 20%. The skew factor
tends to decrease as B_\parallel or temperature grow, or perpendicular field
decreases; for low electron densities and high in-plane fields the skew factor
even changes sign. Finally, we compared the temperature and magnetic field
dependencies of the magneto-oscillations amplitude with predictions of the
interaction correction theory, and found, besides some qualitative
similarities, several quantitative and qualitative differences. To explain
qualitatively our results, we suggested an empirical model that assumes the
existence of easily magnetized triplet scatterers on the Si/SiO_2 interface.",1408.4393v1
2014-08-20,Josephson junction ratchet: effects of finite capacitances,"We study transport in an asymmetric SQUID which is composed of a loop with
three capacitively and resistively shunted Josephson junctions: two in series
in one arm and the remaining one in the other arm. The loop is threaded by an
external magnetic flux and the system is subjected to both a time-periodic and
a constant current. We formulate the deterministic and, as well, the stochastic
dynamics of the SQUID in terms of the Stewart-McCumber model and derive an
equation for the phase difference across one arm, in which an effective
periodic potential is of the ratchet type, i.e. its reflection symmetry is
broken. In doing so, we extend and generalize earlier study by Zapata et al.
[Phys. Rev. Lett. 77, 2292 (1996)] and analyze directed transport in wide
parameter regimes: covering the over-damped to moderate damping regime up to
its fully under-damped regime. As a result we detect the intriguing features of
a negative (differential) conductance, repeated voltage reversals, noise
induced voltage reversals and solely thermal noise-induced ratchet currents. We
identify a set of parameters for which the ratchet effect is most pronounced
and show how the direction of transport can be controlled by tailoring the
external magnetic flux.",1408.4607v1
2014-09-30,Collective modes in two- and three-dimensional electron systems with Rashba spin-orbit coupling,"In addition to charge plasmons, a 2D electron system with Rashba-type
spin-orbit coupling (SOC) also supports three collective modes in the spin
sector: the chiral-spin modes. We study the dispersions of the charge and spin
modes and their coupling to each other within a generalized Random Phase
Approximation for arbitrarily strong SOC, and both in 2D and 3D systems. In
both 2D and 3D, we find that the charge plasmons are coupled to only one of the
three chiral-spin modes. This coupling is shown to affect the dispersions of
the modes at finite but not at zero wavenumbers. In 3D, the chiral-spin modes
are strongly damped by particle-hole excitations and disappear for weak
electron-electron interaction. Landau damping of the chiral-spin modes in 3D is
directly related to the fact that, in contrast to 2D, there is no gap for
particle-hole excitations between spin-split subbands. The gapless continuum is
also responsible for Landau damping of the charge plasmon in 3D - a
qualitatively new feature of the SOC system. We also discuss the optical
conductivity of clean 2D and 3D systems and show that SOC introduces spectral
weight at finite frequency in a such way that the sum rule is satisfied. The
in-plane tranverse chiral-spin mode shows up as dispersing peak in the optical
conductivity at finite number which can can be measured in the presence of
diffraction grating. We also discuss possible experimental manifestations of
chiral-spin modes in semiconductor quantum wells such InGaAs/AlGaAs and 3D
giant Rashba materials of the BiTeI family.",1409.8666v1
2014-11-15,Spin-transfer-torque through antiferromagnetic IrMn,"Spin-transfer-torque, a transfer of angular momentum between the electron
spin and the local magnetic moments, is a promising and key mechanism to
control ferromagnetic materials in modern spintronic devices . However, much
less attention has been paid to the same effect in antiferromagnets. For the
sake of investigating how the spin current interacts with the magnetic moments
in antiferromagnets, we perform spin-torque ferromagnetic resonance
measurements on Co20Fe60B20 4nm/Ir25Mn75 tIrMn nm/Pt 4 nm multilayers under a
spin Hall effect of Pt. The effective magnetic damping in Co20Fe60B20 is
modified by the spin current injected from the Pt layer via the IrMn layer. The
results indicate that the spin current interacts with IrMn magnetic moments and
exerts the anti-damping torque on the magnetic moments of Co20Fe60B20 through
the IrMn. It is also found that the reduction of the exchange bias in the
IrMn/Pt interface degrades the anti-damping torque exerted on the Co20Fe60B20
layer, suggesting the transmission of the spin torque becomes less efficient as
the interface exchange coupling degrades. Our work infers that the magnetic
moments in IrMn can be manipulated by spin torque similarly to the one in a
ferromagnetic layer.",1411.4100v4
2014-11-28,On damped second-order gradient systems,"Using small deformations of the total energy, as introduced in [31], we
establish that damped second order gradient systems
$$u^{\prime\prime}(t)+\gamma u^\prime(t)+\nabla G(u(t))=0,$$may be viewed as
quasi-gradient systems. In order to study the asymptotic behavior of these
systems, we prove that any (nontrivial) desingularizing function appearing in
KL inequality satisfies $\varphi(s)\ge c\sqrt s$ whenever the original function
is definable and $C^2.$ Variants to this result are given. These facts are used
in turn to prove that a desingularizing function of the potential $G$ also
desingularizes the total energy and its deformed versions. Our approach brings
forward several results interesting for their own sake: we provide an
asymptotic alternative for quasi-gradient systems, either a trajectory
converges, or its norm tends to infinity. The convergence rates are also
analyzed by an original method based on a one-dimensional worst-case gradient
system.We conclude by establishing the convergence of solutions of damped
second order systems in various cases including the definable case. The
real-analytic case is recovered and some results concerning convex functions
are also derived.",1411.8005v5
2014-12-08,Variable frequency characterization of interaction at nanoscale in linear dynamic AFM: an FFM primer,"Using electrostatic coupling between an AFM tip and a metallic surface as a
test interaction, we here present the measurement of the force between the tip
and the surface, together with the measurement of the interaction stiffness and
the associated dissipation. These three quantities constitute a full
characterization of the interaction at nanoscale. They are measured
independently, simultaneously and quantitatively at the same place. This is
made possible thanks to a force feedback method that ensures the DC immobility
of the tip and to the simultaneous application of a sub-nanometer oscillation
to the tip. In this established linear regime, stiffness and damping are
directly obtained from amplitude and phase change measurements. The needed
information for this linear transformation is solely the lever properties in
the experimental context. Knowledge of k, its stiffness, its damping
coefficient and Q0, its first resonance frequency is shown to be sufficient in
the frequency range we are here exploring. Finally, we demonstrate that this
method is not restricted to the lever resonance frequency. To the contrary,
this interaction characterization whose resolution is limited by the Brownian
motion, can be used at any frequencies with essentially the same performances.
We believe that simultaneous and independent measurements of force, stiffness
and damping, out of lever resonance, at nanoscale, and within the context of
linear response define a new AFM paradigm that we call Force Feedback
Microscopy (FFM). This article details the use of FFM using a well known and
easy to implement electrostatic interaction between a regular AFM tip and a
metallic surface in air.",1412.2640v1
2015-01-12,Standing Slow MHD Waves in Radiatively Cooling Coronal Loops,"The standing slow magneto-acoustic oscillations in cooling coronal loops are
investigated. There are two damping mechanisms which are considered to generate
the standing acoustic modes in coronal magnetic loops namely thermal conduction
and radiation. The background temperature is assumed to change temporally due
to optically thin radiation. In particular, the background plasma is assumed to
be radiatively cooling. The effects of cooling on longitudinal slow MHD modes
is analytically evaluated by choosing a simple form of radiative function that
ensures the temperature evolution of the background plasma due to radiation
coincides with the observed cooling profile of coronal loops. The assumption of
low-beta plasma leads to neglect the magnetic field perturbation and eventually
reduces the MHD equations to a 1D system modelling longitudinal MHD
oscillations in a cooling coronal loop. The cooling is assumed to occur on a
characteristic time scale much larger than the oscillation period that
subsequently enables using the WKB theory to study the properties of standing
wave. The governing equation describing the time-dependent amplitude of waves
is obtained and solved analytically. The analytically derived solutions are
numerically evaluated to give further insight into the evolution of the
standing acoustic waves. We find that the plasma cooling gives rise to a
decrease in the amplitude of oscillations. In spite of the reduction in damping
rate caused by rising the cooling, the damping scenario of slow standing MHD
waves strongly increases in hot coronal loops.",1501.02689v1
2015-01-12,Beta decay of 252Cf on the way to scission from the exit point,"Upon increasing significantly the nuclear elongation, the beta-decay energy
grows. This paper investigates within a simple yet partly microscopic approach,
the transition rate of the beta decay of the 252Cf nucleus on the way to
scission from the exit point for a spontaneous fission process. A rather crude
classical approximation is made for the corresponding damped collective motion
assumed to be one dimensional. Given these assumptions, we only aim in this
paper at providing the order of magnitudes of such a phenomenon. At each
deformation the energy available for beta decay, is determined from such a
dynamical treatment. Then, for a given elongation, transition rates for the
allowed (Fermi) beta decay are calculated from pair correlated wave functions
obtained within a macroscopic-microscopic approach and then integrated over the
time corresponding to the whole descent from exit to scission. The results are
presented as a function of the damping factor (inverse of the characteristic
damping time) in use in our classical dynamical approach. For instance, in the
case of a descent time from the exit to the scission points of about $10^{-
20}$ second, one finds a total rate of beta decay corresponding roughly to 20
events per year and per milligram of 252Cf. The inclusion of pairing
correlations does not affect much these results.",1501.02701v1
2015-01-13,Fundamental oscillation modes of neutron stars: validity of universal relations,"We study the $f$-mode frequencies and damping times of nonrotating neutron
stars (NS) in general relativity (GR) by solving the linearized perturbation
equations, with the aim to establish ""universal"" relations that depend only
weakly on the equations of state (EOS). Using a more comprehensive set of EOSs,
we re-examine some proposed linearizations that describe the $f$-mode
parameters in terms of mass and radius of the neutron star (NS), and we test a
more recent proposal for expressing the $f$-mode parameters as quadratic
functions of the effective compactness. Our extensive results for each equation
of state considered allow us to study the accuracy of each proposal. In
particular, we find that the damping time deviates quite considerably from the
proposed linearization. We introduce a new universal relation for the product
of the $f$-mode frequency and damping time as a function of the (ordinary)
compactness, which proved to be more accurate. The relations using the
effective compactness on the other hand also fit our data accurately. Our
results show that the maximum oscillation frequency depends strongly on the
EOS, such that the measurement of a high oscillation frequency would rule out
several EOSs. Lastly, we compare the exact mode frequencies to those obtained
in the Cowling approximation, and also to results obtained with a nonlinear
evolution code, validating the implementations of the different approaches.",1501.02970v2
2015-02-13,Magnetohydrodynamic kink waves in nonuniform solar flux tubes: phase mixing and energy cascade to small scales,"Magnetohydrodynamic (MHD) kink waves are ubiquitously observed in the solar
atmosphere. The propagation and damping of these waves may play relevant roles
for the transport and dissipation of energy in the solar atmospheric medium.
However, in the atmospheric plasma dissipation of transverse MHD wave energy by
viscosity or resistivity needs very small spatial scales to be efficient. Here,
we theoretically investigate the generation of small scales in nonuniform solar
magnetic flux tubes due to phase mixing of MHD kink waves. We go beyond the
usual approach based on the existence of a global quasi-mode that is damped in
time due to resonant absorption. Instead, we use a modal expansion to express
the MHD kink wave as a superposition of Alfv\'en continuum modes that are phase
mixed as time evolves. The comparison of the two techniques evidences that the
modal analysis is more physically transparent and describes both the damping of
global kink motions and the building up of small scales due to phase mixing. In
addition, we discuss that the processes of resonant absorption and phase mixing
are intimately linked. They represent two aspects of the same underlying
physical mechanism: the energy cascade from large scales to small scales due to
naturally occurring plasma and/or magnetic field inhomogeneities. This process
may provide the necessary scenario for efficient dissipation of transverse MHD
wave energy in the solar atmospheric plasma.",1502.03949v1
2015-03-24,Spin dynamics and frequency dependence of magnetic damping study in soft ferromagnetic FeTaC film with a stripe domain structure,"Perpendicular magnetic anisotropy (PMA) and low magnetic damping are the key
factors for the free layer magnetization switching by spin transfer torque
technique in magnetic tunnel junction devices. The magnetization precessional
dynamics in soft ferromagnetic FeTaC thin film with a stripe domain structure
was explored in broad band frequency range by employing micro-strip
ferromagnetic resonance technique. The polar angular variation of resonance
field and linewidth at different frequencies have been analyzed numerically
using Landau-Lifshitz-Gilbert equation by taking into account the total free
energy density of the film. The numerically estimated parameters Land\'{e}
$g$-factor, PMA constant, and effective magnetization are found to be 2.1,
2$\times10^{5}$ erg/cm$^{3}$ and 7145 Oe, respectively. The frequency
dependence of Gilbert damping parameter ($\alpha$) is evaluated by considering
both intrinsic and extrinsic effects into the total linewidth analysis. The
value of $\alpha$ is found to be 0.006 at 10 GHz and it increases with
decreasing precessional frequency.",1503.07043v5
2015-03-25,Wave Propagation at Oblique Shocks: How Did Tycho Get Its Stripes?,"We describe a new model for the ""stripes"" of synchrotron radiation seen in
the remnant of Tycho's supernova. In our picture, cosmic rays streaming ahead
of the forward shock generate parallel (with respect to the local magnetic
field direction) circularly polarized Alfven waves that are almost free of
dissipation, and due to being circularly polarized exhibit no spatial variation
of magnetic field strength. Following interaction with the SNR shock with
nonzero obliquity, these parallel waves become obliquely propagating, due the
the wave refraction (different in principle for the different plane wave
components), and dissipation sets in. The magnetosonic polarization decays
faster, due to transit time damping, leaving only the Alfven mode. This
surviving mode now exhibits a spatial variation of the magnetic field, leading
to local maxima and minima in the synchrotron emission, i.e. the stripes. We
attribute the initial wave generation to the Bell instability, which in
contrast to the resonant generation of upstream Alfven waves, gives rise to a
preferred wavelength, and hence the single wave period at which the stripes are
seen. Based on estimates for damping rates due to turbulent cascade and transit
time damping, we estimate the dependence of the visibility of the stripes on
the shock obliquity, and determine a maximum cosmic ray energy in Tycho's SNR
in the range $6\times 10^{14} - 1\times 10^{15}$ eV.",1503.07497v1
2015-03-30,Superradiance and instability of small rotating charged AdS black holes in all dimensions,"Rotating small AdS black holes exhibit the superradiant instability to
low-frequency scalar perturbations, which is amenable to a complete analytic
description in four dimensions. In this paper, we extend this description to
all higher dimensions, focusing on slowly rotating charged AdS black holes with
a single angular momentum. We divide the spacetime of these black holes into
the near-horizon and far regions and find solutions to the scalar wave equation
in each of these regions. Next, we perform the matching of these solutions in
the overlap between the regions, by employing the idea that the orbital quantum
number $ \ell $ can be thought of as an approximate integer. Thus, we obtain
the complete low-frequency solution that allows us to calculate the complex
frequency spectrum of quasinormal modes, whose imaginary part is determined by
a small damping parameter. Finally, we find a remarkably instructive expression
for the damping parameter, which appears to be a complex quantity in general.
We show that the real part of the damping parameter can be used to give a {\it
universal} analytic description of the superradiant instability for slowly
rotating charged AdS black holes in all spacetime dimensions.",1503.08607v2
2015-04-12,Evolution of Kinetic and Magnetic Energy in Intra Cluster Media,"Intra Cluster Media (ICMs) located at galaxy clusters is in the state of hot,
tenuous, magnetized, and highly ionized X-ray emitting plasmas. This overall
collisionless, viscous, and conductive magnetohydrodynamic (MHD) turbulence in
ICM is simulated using hyper and physical magnetic diffusivity. The results
show that fluctuating random plasma motion amplifies the magnetic field, which
cascades toward the diffusivity scale passing through the viscous scale. The
kinetic eddies in the subviscous scale are driven and constrained by the
magnetic tension which finally gets balanced with the highly damping effect of
the kinetic eddies. However, the saturated kinetic energy spectrum is deeper
than that of the incompressible or compressible hydrodynamics fluid. To explain
this unusual field profile we set up two simultaneous differential equations
for the kinetic and magnetic energy spectrum using an Eddy Damped Quasi Normal
Markovianized (EDQNM) approximation. The analytic solution tells us that the
magnetic energy in addition to the viscous damping effect constrains the plasma
motion leading to the power spectra: kinetic energy spectrum $E_V^k\sim k^{-3}$
and corresponding representative magnetic energy spectrum $E_M^k\sim k^{-1/2}$.
Also the comparison of simulation results with different resolutions and
magnetic diffusivities implies the role of small scale magnetic energy in
dynamo.",1504.02940v3
2015-04-17,Effective Action for Cosmological Scalar Fields at Finite Temperature,"Scalar fields appear in many theories beyond the Standard Model of particle
physics. In the early universe, they are exposed to extreme conditions,
including high temperature and rapid cosmic expansion. Understanding their
behavior in this environment is crucial to understand the implications for
cosmology. We calculate the finite temperature effective action for the field
expectation value in two particularly important cases, for damped oscillations
near the ground state and for scalar fields with a flat potential. We find that
the behavior in both cases can in good approximation be described by a complex
valued effective potential that yields Markovian equations of motion. Near the
potential minimum, we recover the solution to the well-known Langevin equation.
For large field values we find a very different behavior, and our result for
the damping coefficient differs from the expressions frequently used in the
literature. We illustrate our results in a simple scalar model, for which we
give analytic approximations for the effective potential and damping
coefficient. We also provide various expressions for loop integrals at finite
temperature that are useful for future calculations in other models.",1504.04444v2
2015-05-19,The elusive HI-> H2 transition in high-z damped Lyman-alpha systems,"We study the H2 molecular content in high redshift damped Lyman-alpha systems
(DLAs) as a function of the HI column density. We find a significant increase
of the H2 molecular content around log N(HI) (cm^-2)~21.5-22, a regime unprobed
until now in intervening DLAs, beyond which the majority of systems have log
N(H2) > 17. This is in contrast with lines of sight towards nearby stars, where
such H2 column densities are always detected as soon as log N(HI)>20.7. This
can qualitatively be explained by the lower average metallicity and possibly
higher surrounding UV radiation in DLAs. However, unlike in the Milky Way, the
overall molecular fractions remain modest, showing that even at a large N(HI)
only a small fraction of overall HI is actually associated with the
self-shielded H2 gas. Damped Lyman-alpha systems with very high-N(HI) probably
arise along quasar lines of sight passing closer to the centre of the host
galaxy where the gas pressure is higher. We show that the colour changes
induced on the background quasar by continuum (dust) and line absorption (HI
Lyman and H2 Lyman & Werner bands) in DLAs with log N(HI)~22 and metallicity
~1/10 solar is significant, but not responsible for the long-discussed lack of
such systems in optically selected samples. Instead, these systems are likely
to be found towards intrinsically fainter quasars that dominate the quasar
luminosity function. Colour biasing should in turn be severe at higher
metallicities.",1505.04997v1
2015-06-11,Dynamics near the subcritical transition of the 3D Couette flow I: Below threshold case,"We study small disturbances to the periodic, plane Couette flow in the 3D
incompressible Navier-Stokes equations at high Reynolds number $\textbf{Re}$.
We prove that for sufficiently regular initial data of size $\epsilon \leq
c_0\textbf{Re}^{-1}$ for some universal $c_0 > 0$, the solution is global,
remains within $O(c_0)$ of the Couette flow in $L^2$, and returns to the
Couette flow as $t \rightarrow \infty$. For times $t \gtrsim
\textbf{Re}^{1/3}$, the streamwise dependence is damped by a mixing-enhanced
dissipation effect and the solution is rapidly attracted to the class of ""2.5
dimensional"" streamwise-independent solutions referred to as streaks. Our
analysis contains perturbations that experience a transient growth of kinetic
energy from $O(\textbf{Re}^{-1})$ to $O(c_0)$ due to the algebraic linear
instability known as the lift-up effect. Furthermore, solutions can exhibit a
direct cascade of energy to small scales. The behavior is very different from
the 2D Couette flow, in which stability is independent of $\textbf{Re}$,
enstrophy experiences a direct cascade, and inviscid damping is dominant
(resulting in a kind of inverse energy cascade). In 3D, inviscid damping will
play a role on one component of the velocity, but the primary stability
mechanism is the mixing-enhanced dissipation. Central to the proof is a
detailed analysis of the interplay between the stabilizing effects of the
mixing and enhanced dissipation and the destabilizing effects of the lift-up
effect, vortex stretching, and weakly nonlinear instabilities connected to the
non-normal nature of the linearization.",1506.03720v1
2015-06-12,Casimir Friction Between Polarizable Particle and Half-Space with Radiation Damping and Image Damping at Zero Temperature,"Casimir friction between a polarizable particle and a semi-infinite space is
a delicate physical phenomenon, as it concerns the interaction between a
microscopic quantum particle and a semi-infinite reservoir. Not unexpectedly,
results obtained in the past about the friction force obtained via different
routes are sometimes, at least apparently, wildly different from each other.
  Recently, we considered the Casimir friction force for two dielectric
semi-infinite plates moving parallel to each other [J. S. H{\o}ye and I.
Brevik, Eur. Phys. J. D {\bf 68}, 61 (2014)], and managed to get essential
agreement with results obtained by Pendry (1997), Volokitin and Persson (2007),
and Barton (2011). Our method was based upon use of the Kubo formalism. In the
present paper we focus on the interaction between a polarizable particle and a
dielectric half-space again, and calculate the friction force using the same
basic method as before. The new ingredient in the present analysis is that we
take into account radiative damping, and derive the modifications thereof. Some
comparisons are also made with works from others. Essential agreement with the
results of Intravaia, Behunin, and Dalvit can also be achieved using the
modification of the atomic polarizability by the metallic plate.",1506.03937v2
2015-07-08,Periods and damping rates of fast sausage oscillations in multi-shelled coronal loops,"Standing sausage modes are important in interpreting quasi-periodic
pulsations in the lightcurves of solar flares. Their periods and damping times
play an important role in seismologically diagnosing key parameters like the
magnetic field strength in regions where flare energy is released. Usually such
applications are based on theoretical results neglecting unresolved fine
structures in magnetized loops. However, the existence of fine structuring is
suggested on both theoretical and observational grounds. Adopting the framework
of cold magnetohydrodynamics (MHD), we model coronal loops as magnetized
cylinders with a transverse equilibrium density profile comprising a monolithic
part and a modulation due to fine structuring in the form of concentric shells.
The equation governing the transverse velocity perturbation is solved with an
initial-value-problem approach, and the effects of fine structuring on the
periods $P$ and damping times $\tau$ of global, leaky, standing sausage modes
are examined. A parameter study shows that fine structuring, be it periodically
or randomly distributed, brings changes of only a few percent to $P$ and $\tau$
when there are more than about ten shells. The monolithic part, its steepness
in particular, plays a far more important role in determining $P$ and $\tau$.
We conclude that when measured values of $P$ and $\tau$ of sausage modes are
used for seismological purposes, it is justified to use theoretical results
where the effects due to fine structuring are neglected.",1507.02169v1
2015-06-23,Resonant absorption of kink magnetohydrodynamic waves by a magnetic twist in coronal loops,"There is ample evidence of twisted magnetic structures in the solar corona.
This motivates us to consider the magnetic twist as the cause of Alfven
frequency continuum in the coronal loops, which can support the resonant
absorption as a rapid damping mechanism for the observed coronal kink
magnetohydrodynamic (MHD) oscillations. We model a coronal loop with a straight
cylindrical magnetic flux tube which has constant but different densities in
the interior and exterior regions. The magnetic field is assumed to be constant
and aligned with the cylinder axis everywhere except a thin layer near the
boundary of the flux tube which has an additional small magnetic field twist.
Then, we investigate a number of possible instabilities that may arise in our
model. In the thin tube thin boundary approximation, we derive the dispersion
relation and solve it analytically to obtain the frequencies and damping rates
of the fundamental (l=1) and first/second overtone (l=2,3) kink (m=1) MHD
modes. We conclude that the resonant absorption by the magnetic twist can
justify the rapid damping of kink MHD waves observed in coronal loops.
Furthermore, the magnetic twist in the inhomogeneous layer can cause deviations
from P1/P2=2 and P1/P3=3 which are comparable with the observations.",1507.02653v4
2015-07-23,Asteroseismology of rapidly rotating neutron stars - an alternative approach,"In the present paper we examine gravitational wave asteroseismology relations
for f-modes of rapidly rotating neutron stars. An approach different to the
previous studies is employed - first, the moment of inertia is used instead of
the stellar radius, and second, the normalization of the oscillation
frequencies and damping times is different. It was shown that in the
non-rotating case this can lead to a much stronger equation of state
independence and our goal is to generalize the static relations to the rapidly
rotating case and values of the spherical mode number $l\ge2$. We employ
realistic equations of state that cover a very large range of stiffness in
order to check better the universality of the relations. At the end we explore
the inverse problem, i.e. obtain the neutron star parameters from the observed
gravitational frequencies and damping times. It turns out that with this new
set of relations we can solve the inverse problem with a very good accuracy
using three frequencies that was not possible in the previous studies where one
needs also the damping times. The asteroseismology relations are also
particularly good for the massive rapidly rotating models that are subject to
secular instabilities.",1507.06606v1
2015-07-31,Eccentricity Evolution Through Accretion of Protoplanets,"Most of super-Earths detected by the radial velocity (RV) method have
significantly smaller eccentricities than the eccentricities corresponding to
velocity dispersion equal to their surface escape velocity (""escape
eccentricities""). If orbital instability followed by giant impacts among
protoplanets that have migrated from outer region is considered, it is usually
considered that eccentricities of the merged bodies become comparable to those
of orbital crossing bodies, which are excited up to their escape eccentricities
by close scattering. However, the eccentricity evolution in the {\it in situ}
accretion model has not been studied in detail. Here, we investigate the
eccentricity evolution through {\it N}-body simulations. We have found that the
merged planets tend to have much smaller eccentricities than the escape
eccentricities due to very efficient collision damping. If the protoplanet
orbits are initially well separated and their eccentricities are securely
increased, an inner protoplanet collides at its apocenter with an outer
protoplanet at its pericenter. The eccentricity of the merged body is the
smallest for such configuration. Orbital inclinations are also damped by this
mechanism and planets tend to share a same orbital plane, which is consistent
with {\it Kepler} data. Such efficient collision damping is not found when we
start calculations from densely packed orbits of the protoplanets. If the
protoplanets are initially in the mean-motion resonances, which corresponds to
well separated orbits, the {\it in situ} accretion model well reproduces the
features of eccentricities and inclinations of multiple super-Earths/Earth
systems discovered by RV and {\it Kepler} surveys.",1507.08809v1
2015-08-25,Effects of inertia on the steady-shear rheology of disordered solids,"We study the finite-shear-rate rheology of disordered solids by means of
molecular dynamics simulations in two dimensions. By systematically varying the
damping magnitude $\zeta$ in the low-temperature limit, we identify two well
defined flow regimes, separated by a thin (temperature-dependent) crossover
region. In the overdamped regime, the athermal rheology is governed by the
competition between elastic forces and viscous forces, whose ratio gives the
Weissenberg number $Wi= \zeta \dot\gamma$ (up to elastic parameters); the
macroscopic stress $\Sigma$ follows the frequently encountered Herschel-Bulkley
law $\Sigma= \Sigma\_0 + k \sqrt{Wi}$, with yield stress
$\Sigma\_0\textgreater{}0$. In the underdamped (inertial) regime, dramatic
changes in the rheology are observed for low damping: the flow curve becomes
non-monotonic. This change is not caused by longer-lived correlations in the
particle dynamics at lower damping; instead, for weak dissipation, the sample
heats up considerably due to, and in proportion to, the driving. By suitably
thermostatting more or less underdamped systems, we show that their rheology
only depends on their kinetic temperature and the shear rate, rescaled with
Einstein's vibration frequency.",1508.06067v3
2015-09-01,Persistence of a Non-Equilibrium State: Observation of a Boltzmannian Special Case,"Well before the atomistic nature of matter was experimentally established,
Ludwig Boltzmann's audacious effort to explain the macroscopic world of human
experience in terms of the workings of an unseen microscopic world met with
vigorous opposition. A contentious point was the problem of irreversibility:
the microscopic equations of motion are reversible, yet friction and viscosity
cause things always to slow down and warm up, never to speed up and cool down.
What was worse, Boltzmann himself discovered that his transport equation
predicts special cases in which gases never come to thermal equilibrium, a
particular example being that the monopole ""breathe"" mode of gas will never
damp if it is confined in 3D to a perfectly isotropic harmonic potential. Such
absences of damping were not observed in nature. Nondamping of a monopole mode
in lower dimensional systems has only very recently been observed, using cold
atoms. Kinoshita et al. and Chevy et al. have experimentally observed
suppressed relaxation in highly elongated geometries. The difficulty in
generating sufficiently spherical harmonic confinement for ultracold atoms,
however, has meant that Boltzmann's fully 3D, isotropic case has never been
observed. With the development of a new magnetic trap capable of producing
near-spherical harmonic confinement for ultracold atoms, we have been able to
make the first observation of this historically significant oddity. We observe
a monopole mode for which the collisional contribution to damping vanishes, a
long-delayed vindication for Boltzmann's microscopic theory.",1509.00366v1
2015-09-07,Spectral inequality and resolvent estimate for the bi-Laplace operator,"On a compact Riemannian manifold with boundary, we prove a spectral
inequality for the bi-Laplace operator in the case of so-called ""clamped""
boundary conditions , that is, homogeneous Dirichlet and Neumann conditions
simultaneously. We also prove a resolvent estimate for the generator of the
damped plate semigroup associated with these boundary conditions. The spectral
inequality allows one to observe finite sums of eigenfunctions for this
fourth-order elliptic operator, from an arbitrary open subset of the manifold.
Moreover, the constant that appears in the inequality grows as exp(C$\mu$ 1/4)
where $\mu$ is the largest eigenvalue associated with the eigenfunctions
appearing in the sum. This type of inequality is known for the Laplace
operator. As an application, we obtain a null-controllability result for a
higher-order parabolic equation. The resolvent estimate provides the spectral
behavior of the plate semigroup generator on the imaginary axis. This type of
estimate is known in the case of the damped wave semigroup. As an application ,
we deduce a stabilization result for the damped plate equation, with a log-type
decay. The proofs of both the spectral inequality and the resolvent estimate
are based on the derivation of different types of Carleman estimates for an
elliptic operator related to the bi-Laplace operator: in the interior and at
some boundaries. One of these estimates exhibits a loss of one full derivative.
Its proof requires the introduction of an appropriate semi-classical calculus
and a delicate microlocal argument.",1509.02098v5
2015-09-14,Nonlinear Energetic Particle Transport in the Presence of Multiple Alfvenic Waves in ITER,"This work presents the results of a multi mode ITER study on Toroidal Alfven
Eigenmodes, using the nonlinear hybrid HAGIS-LIGKA model. It is found that main
conclusions from earlier studies of ASDEX Upgrade discharges can be transferred
to the ITER scenario: global, nonlinear effects are crucial for the evolution
of the multi mode scenario. This work focuses on the ITER 15 MA baseline
scenario with with a safety factor at the magnetic axis of $q_0 =$ 0.986. The
least damped eigenmodes of the system are identified with the gyrokinetic,
non-perturbative LIGKA solver, concerning mode structure, frequency and
damping. Taking into account all weakly damped modes that can be identified
linearly, nonlinear simulations with HAGIS reveal strong multi mode behavior:
while in some parameter range, quasi-linear estimates turn out to be reasonable
approximations for the nonlinearly relaxed energetic particle profile, under
certain conditions low-n TAE branches can be excited. As a consequence, not
only grow amplitudes of all modes to (up to orders of magnitude) higher values
compared to the single mode cases but also, strong redistribution is triggered
in the outer radial area between $\rho_\mathrm{pol} =$ 0.6 and 0.85, far above
quasi-linear estimates.",1509.04010v1
2015-09-30,Dynamic Quantum Tomography Model for Phase-Damping Channels,"In this article we propose a dynamic quantum tomography model for open
quantum systems with evolution given by phase-damping channels. Mathematically,
these channels correspond to completely positive trace-preserving maps defined
by the Hadamard product of the initial density matrix with a time-dependent
matrix which carries the knowledge about the evolution. Physically, there is a
strong motivation for considering this kind of evolution because such channels
appear naturally in the theory of open quantum systems. The main idea behind a
dynamic approach to quantum tomography claims that by performing the same kind
of measurement at some time instants one can obtain new data for state
reconstruction. Thus, this approach leads to a decrease in the number of
distinct observables which are required for quantum tomography; however, the
exact benefit for employing the dynamic approach depends strictly on how the
quantum system evolves in time. Algebraic analysis of phase-damping channels
allows one to determine optimal criteria for quantum tomography of systems in
question. General theorems and observations presented in the paper are
accompanied by a specific example, which shows step by step how the theory
works. The results introduced in this article can potentially be applied in
experiments where there is a tendency a look at quantum tomography from the
point of view of economy of measurements, because each distinct kind of
measurement requires, in general, preparing a separate setup.",1509.09318v3
2015-10-24,Propagation of GeV neutrinos through Earth,"We have studied the Earth matter effect on the oscillation of upward going
GeV neutrinos by taking into account the three active neutrino flavors. For
neutrino energy in the range 3 to 12 GeV we observed three distinct resonant
peaks for the oscillation process $\nu_e\leftrightarrow \nu_{\mu,\tau}$ in
three \textit{distinct} densities. However, according to the most realistic
density profile of the Earth, the second peak at neutrino energy 6.18 GeV
corresponding to the density $6.6\,g/cm^3$ does not exist. So the resonance at
this energy can not be of MSW-type. For the calculation of observed flux of
these GeV neutrinos on Earth, we considered two different flux ratios at the
source, the standard scenario with the flux ratio $1:2:0$ and the muon damped
scenario with $0:1:0$. It is observed that at the detector while the standard
scenario gives the observed flux ratio $1:1:1$, the muon damped scenario has a
different ratio. For muon damped case with $E_{\nu} < 20$ GeV, we always get
observed neutrino fluxes as $\Phi_{\nu_e} < \Phi_{\nu_\mu}\simeq
\Phi_{\nu_\tau}$ and for $E_{\nu} > 20$ GeV, we get the average
$\Phi_{\nu_e}\sim 0$ and $\Phi_{\nu_\mu}\simeq \Phi_{\nu_\tau}\simeq 0.45$. The
upcoming PINGU will be able to shed more light on the nature of the resonance
in these GeV neutrinos and hopefully will also be able to discriminate among
different processes of neutrino production at the source in GeV energy range.",1510.07103v2
2015-11-18,Surface waves propagation on a turbulent flow forced electromagnetically,"We study the propagation of monochromatic surface waves on a turbulent flow.
The flow is generated in a layer of liquid metal by an electromagnetic forcing.
This forcing creates a quasi two-dimensional (2D) turbulence with strong
vertical vorticity. The turbulent flow contains much more energy than the
surface waves. In order to focus on the surface wave, the deformations induced
by the turbulent flow are removed. This is done by performing a coherent phase
averaging. For wavelengths smaller than the forcing lengthscale, we observe a
significant increase of the wavelength of the propagating wave that has not
been reported before. We suggest that it can be explained by the random
deflection of the wave induced by the velocity gradient of the turbulent flow.
Under this assumption, the wavelength shift is an estimate of the fluctuations
of deflection angle. The local measurements of the wave frequency far from the
wavemaker do not reveal such systematic behavior, although a small shift is
measured. Finally we quantify the damping enhancement induced by the turbulent
flow. We review various theoretical scaling laws proposed previously. Most of
them propose a damping that increases as the square of Froude number. In
contrast, our experimental results show a turbulent damping increasing linearly
with the Froude number. We interpret this linear behaviour as a balance between
the time spent by a wave to cross a turbulent structure with the turbulent
mixing time. The larger is the ratio of these 2 times, the more energy is
extracted from the progressive wave. Finally, mechanisms of energy exchange and
open issues are discussed and further studies are proposed.",1511.05900v1
2016-01-08,Kinetic Simulation of Slow Magnetosonic Waves and Quasi-periodic Upflows in the Solar Corona,"Quasi-periodic disturbances of emission-line parameters are frequently
observed in the corona. These disturbances propagate upward along the magnetic
field with speeds $\sim100~\rm{km~s}^{-1}$. This phenomenon has been
interpreted as evidence of the propagation of slow magnetosonic waves or argued
to be signature of the intermittent outflows superposed on the background
plasmas. Here we aim to present a new ""wave + flow"" model to interpret these
observations. In our scenario, the oscillatory motion is a slow mode wave, and
the flow is associated with a beam created by the wave-particle interaction
owing to Landau resonance. With the help of a Vlasov model, we simulate the
propagation of the slow mode wave and the generation of the beam flow. We find
that weak periodic beam flows can be generated owing to Landau resonance in the
solar corona, and the phase with strongest blueward asymmetry is ahead of that
with strongest blueshift by about 1/4 period. We also find that the slow wave
damps to the level of 1/e after the transit time of two wave periods, owing to
Landau damping and Coulomb collisions in our simulation. This damping time
scale is similar to that resulting from thermal-conduction in the
magnetohydrodynamics regime. The beam flow is weakened/attenuated with
increasing wave period and decreasing wave amplitude since Coulomb collision
becomes more and more dominant over the wave action. We suggest that this ""wave
+ flow"" kinetic model provides an alternative explanation for the observed
quasi-periodic propagating perturbations in various parameters in the solar
corona.",1601.01823v1
2016-01-25,Comprehensive evaluation of the linear stability of Alfvén eigenmodes driven by alpha particles in an ITER baseline scenario,"The linear stability of Alfv\'en eigenmodes in the presence of fusion-born
alpha particles is thoroughly assessed for two variants of an ITER baseline
scenario, which differ significantly in their core and pedestal temperatures. A
systematic approach is used that considers all possible eigenmodes for a given
magnetic equilibrium and determines their growth rates due to alpha-particle
drive and Landau damping on fuel ions, helium ashes and electrons. This
extensive stability study is efficiently conducted through the use of a
specialized workflow that profits from the performance of the hybrid MHD
drift-kinetic code $\mbox{CASTOR-K}$ (Borba D. and Kerner W. 1999 J. Comput.
Phys. ${\bf 153}$ 101; Nabais F. ${\it et\,al}$ 2015 Plasma Sci. Technol. ${\bf
17}$ 89), which can rapidly evaluate the linear growth rate of an eigenmode. It
is found that the fastest growing instabilities in the aforementioned ITER
scenario are core-localized, low-shear toroidal Alfv\'en eigenmodes. The
largest growth-rates occur in the scenario variant with higher core
temperatures, which has the highest alpha-particle density and density
gradient, for eigenmodes with toroidal mode numbers $n\approx30$. Although
these eigenmodes suffer significant radiative damping, which is also evaluated,
their growth rates remain larger than those of the most unstable eigenmodes
found in the variant of the ITER baseline scenario with lower core
temperatures, which have $n\approx15$ and are not affected by radiative
damping.",1601.06621v1
2016-01-27,Flash ionisation signature in coherent cyclotron emission from Brown Dwarfs,"Brown dwarfs form mineral clouds in their atmospheres, where charged
particles can produce large-scale discharges in form of lightning resulting in
a substantial sudden increase of local ionisation. Brown dwarfs are observed to
emit cyclotron radio emission. We show that signatures of strong transient
atmospheric ionisation events (flash ionisation) can be imprinted on a
pre-existing radiation. Detection of such flash ionisation events will open
investigations into the ionisation state and atmospheric dynamics. Such
ionisation events can also result from explosion shock waves, bursts or
eruptions. We present an analytical model that describes the modulation of a
pre-existing electromagnetic radiation by a time-dependent (flash) conductivity
that is characteristic for flash ionisation events like lightning. Our
conductivity model reproduces the conductivity function derived from
observations of Terrestrial Gamma Ray Flashes, and is applicable to
astrophysical objects with strong temporal variations in the local ionization,
as in planetary atmospheres and protoplanetary disks. We show that the field
responds with a characteristic flash-shaped pulse to a conductivity flash of
intermediate intensity. More powerful ionisation events result in smaller
variations of the initial radiation, or in its damping. We show that the
characteristic damping of the response field for high-power initial radiation
carries information about the ionisation flash magnitude and duration. The
duration of the pulse amplification or the damping is consistently shorter for
larger conductivity variations and can be used to evaluate the intensity of the
flash ionisation. Our work suggests that cyclotron emission could be probe
signals for electrification processes inside BD atmosphere.",1601.07474v1
2016-02-02,Sudden-quench dynamics of Bardeen-Cooper-Schrieffer states in deep optical lattices,"We determine the exact dynamics of an initial Bardeen-Cooper-Schrieffer (BCS)
state of ultra-cold atoms in a deep hexagonal optical lattice. The dynamical
evolution is triggered by a quench of the lattice potential, such that the
interaction strength $U_f$ is much larger than the hopping amplitude $J_f$. The
quench initiates collective oscillations with frequency $|U_f|/(2\pi)$ in the
momentum occupation numbers and imprints an oscillating phase with the same
frequency on the BCS order parameter $\Delta$. The oscillation frequency of
$\Delta$ is not reproduced by treating the time evolution in mean-field theory.
In our theory, the momentum noise (i.e. density-density) correlation functions
oscillate at frequency $|U_f|/2\pi$ as well as at its second harmonic. For a
very deep lattice, with zero tunneling energy, the oscillations of momentum
occupation numbers are undamped. Non-zero tunneling after the quench leads to
dephasing of the different momentum modes and a subsequent damping of the
oscillations. The damping occurs even for a finite-temperature initial BCS
state, but not for a non-interacting Fermi gas. Furthermore, damping is
stronger for larger order parameter and may therefore be used as a signature of
the BCS state. Finally, our theory shows that the noise correlation functions
in a honeycomb lattice will develop strong anti-correlations near the Dirac
point.",1602.00979v2
2016-03-09,Conclusive Identification of Quantum Channels via Monogamy of Quantum Correlations,"We investigate the action of local and global noise on monogamy of quantum
correlations, when monogamy scores are considered as observables, and
three-qubit systems are subjected to global noise and various local noisy
channels, namely, amplitude-damping, phase-damping, and depolarizing channels.
We show that the dynamics of monogamy scores corresponding to negativity and
quantum discord, in the case of generalized W states, as inputs to the noisy
channels, can exhibit non-monotonic dynamics with respect to increasing noise
parameter, which is in contrast to the monotonic decay of monogamy scores when
generalized Greenberger-Horne-Zeilinger states are exposed to noise. We
quantify the persistence of monogamy against noise via a characteristic value
of the noise parameter, and show that depolarizing noise destroys monogamy of
quantum correlation faster compared to other noisy channels. We demonstrate
that the negativity monogamy score is more robust than the quantum discord
monogamy score, when the noise is of the phase-damping type. We also
investigate the variation of monogamy with increasing noise for arbitrary
three-qubit pure states as inputs. Finally, depending on these results, we
propose a two-step protocol, which can conclusively identify the type of noise
applied to the quantum system, by using generalized Greenberger-Horne-Zeilinger
and generalized W states as resource states. We discuss a possible
generalization of the results to higher number of parties.",1603.02801v3
2016-06-14,Landau damping to partially locked states in the Kuramoto model,"In the Kuramoto model of globally coupled oscillators, partially locked
states (PLS) are stationary solutions that incorporate the emergence of partial
synchrony when the interaction strength increases. While PLS have long been
considered, existing results on their stability are limited to neutral
stability of the linearized dynamics in strong topology, or to specific
invariant subspaces (obtained via the so-called Ott-Antonsen (OA) ansatz) with
specific frequency distributions for the oscillators. In the mean field limit,
the Kuramoto model shows various ingredients of the Landau damping mechanism in
the Vlasov equation. This analogy has been a source of inspiration for
stability proofs of regular Kuramoto equilibria. Besides, the major
mathematical issue with PLS asymptotic stability is that these states consist
of heterogeneous and singular measures. Here, we establish an explicit
criterion for their spectral stability and we prove their local asymptotic
stability in weak topology, for a large class of analytic frequency marginals.
The proof strongly relies on a suitable functional space that contains (Fourier
transforms of) singular measures, and for which the linearized dynamics is well
under control. For illustration, the stability criterion is evaluated in some
standard examples. We show in particular that no loss of generality results in
assuming the OA ansatz. To our best knowledge, our result provides the first
proof of Landau damping to heterogeneous and irregular equilibria, in absence
of dissipation.",1606.04470v1
2016-06-29,On the global existence and blowup of smooth solutions to the multi-dimensional compressible Euler equations with time-depending damping,"In this paper, we are concerned with the global existence and blowup of
smooth solutions to the multi-dimensional compressible Euler equations with
time-depending damping \begin{equation*}
  \partial_t\rho+\operatorname{div}(\rho u)=0, \quad
  \partial_t(\rho u)+\operatorname{div}\left(\rho u\otimes
u+p\,I_d\right)=-\alpha(t)\rho u, \quad
  \rho(0,x)=\bar \rho+\varepsilon\rho_0(x),\quad u(0,x)=\varepsilon u_0(x),
\end{equation*} where $x=(x_1, \cdots, x_d)\in\Bbb R^d$ $(d=2,3)$, the
frictional coefficient is $\alpha(t)=\frac{\mu}{(1+t)^\lambda}$ with
$\lambda\ge0$ and $\mu>0$, $\bar\rho>0$ is a constant, $\rho_0,u_0 \in
C_0^\infty(\Bbb R^d)$, $(\rho_0,u_0)\not\equiv 0$, $\rho(0,x)>0$, and
$\varepsilon>0$ is sufficiently small. One can totally divide the range of
$\lambda\ge0$ and $\mu>0$ into the following four cases:
  Case 1: $0\le\lambda<1$, $\mu>0$ for $d=2,3$;
  Case 2: $\lambda=1$, $\mu>3-d$ for $d=2,3$;
  Case 3: $\lambda=1$, $\mu\le 3-d$ for $d=2$;
  Case 4: $\lambda>1$, $\mu>0$ for $d=2,3$.
  \noindent We show that there exists a global $C^{\infty}-$smooth solution
$(\rho, u)$ in Case 1, and Case 2 with $\operatorname{curl} u_0\equiv 0$, while
in Case 3 and Case 4, in general, the solution $(\rho, u)$ blows up in finite
time. Therefore, $\lambda=1$ and $\mu=3-d$ appear to be the critical power and
critical value, respectively, for the global existence of small amplitude
smooth solution $(\rho, u)$ in $d-$dimensional compressible Euler equations
with time-depending damping.",1606.08935v1
2016-07-20,Electromagnon in the Z-type hexaferrite $({\rm Ba}_{x}{\rm Sr}_{1-x})_3\rm Co_2Fe_{24}O_{41}$,"We studied experimentally the high-temperature magnetoelectric $({\rm
Ba}_{x}{\rm Sr}_{1-x})_3\rm Co_2Fe_{24}O_{41}$ prepared as ceramics (x = 0,
0.2) and a single crystal (x = 0.5) using inelastic neutron scattering, THz
time-domain, Raman and far-infrared spectroscopies. The spectra, measured with
varying temperature and magnetic field, reveal rich information about the
collective spin and lattice excitations. In the ceramics, we observed an
infrared-active magnon which is absent in $E^{\omega}\perp z$ polarized THz
spectra of the crystal, and we assume that it is an electromagnon active in
$E^{\omega} \| z$ polarized spectra. On heating from 7 to 250 K, the frequency
of this electromagnon drops from 36 to 25 cm$^{-1}$ and its damping gradually
increases, so it becomes overdamped at room temperature. Applying external
magnetic field has a similar effect on the damping and frequency of the
electromagnon, and the mode is no more observable in the THz spectra above 2 T,
as the transverse-conical magnetic structure transforms into a collinear one.
Raman spectra reveal another spin excitation with a slightly different
frequency and much higher damping. Upon applying magnetic field higher than 3
T, in the low-frequency part of the THz spectra, a narrow excitation appears
whose frequency linearly increases with magnetic field. We interpret this
feature as the ferromagnetic resonance.",1607.05878v1
2016-07-28,Damping of the Milky Way bar by manifold-driven spirals,"We describe a new phenomenon of `bar damping' that may have played an
important role in shaping the Milky Way bar and bulge as well as its spiral
structure. We use a collisionless N-body simulation of a Milky Way-like galaxy
initially composed of a dark matter halo and an exponential disk with Toomre
parameter slightly above unity. In this configuration, dominated by the disk in
the center, a bar forms relatively quickly, after 1 Gyr of evolution. This is
immediately followed by the formation of two manifold-driven spiral arms and
the outflow of stars that modifies the potential in the vicinity of the bar,
apparently shifting the position of the L_1/L_2 Lagrange points. This
modification leads to the shortening of the bar and the creation of a next
generation of manifold-driven spiral arms at a smaller radius. The process
repeats itself a few times over the next 0.5 Gyr resulting in further
substantial weakening and shortening of the bar. The time when the damping
comes to an end coincides with the first buckling episode in the bar which
rebuilds the orbital structure so that no more new spiral arms are formed. The
morphology of the bar and the spiral structure at this time show remarkable
similarity to the present properties of the Milky Way. Later on, the bar starts
to grow rather steadily again, weakened only by subsequent buckling episodes
occurring at more distant parts of the disk.",1607.08339v2
2017-02-07,Constraining color flavor locked strange stars in the gravitational wave era,"We perform a detailed analysis of the fundamental mode of non-radial
pulsations of color flavor locked strange stars. Solving the general
relativistic equations for non-radial pulsations for an equation of state
derived within the MIT bag model, we calculate the frequency and the
gravitational damping time of the fundamental mode for all the parametrizations
of the equation of state that lead to self-bound matter.
  Our results show that color flavor locked strange stars can emit
gravitational radiation in the optimal range for present gravitational wave
detectors and that it is possible to constrain the equation of state's
parameters if the fundamental oscillation mode is observed and the stellar mass
is determined.
  We also show that the $f$-mode frequency can be fitted as a function of the
square root of the average stellar density $\sqrt{M/R^3}$ by a single linear
relation that fits quite accurately the results for all parametrizations of the
equation of state. All results for the damping time can also be fitted as a
function of the compactness $M/R$ by a single empirical relation. Therefore, if
a given compact object is identified as a color flavor locked strange star
these two relations could be used to determine the mass and the radius from the
knowledge of the frequency and the damping time of gravitational waves from the
$f$ mode.",1702.02081v1
2017-02-16,"Designing the Optimal Bit: Balancing Energetic Cost, Speed and Reliability","We consider the technologically relevant costs of operating a reliable bit
that can be erased rapidly. We find that both erasing and reliability times are
non-monotonic in the underlying friction, leading to a trade-off between
erasing speed and bit reliability. Fast erasure is possible at the expense of
low reliability at moderate friction, and high reliability comes at the expense
of slow erasure in the underdamped and overdamped limits. Within a given class
of bit parameters and control strategies, we define ""optimal"" designs of bits
that meet the desired reliability and erasing time requirements with the lowest
operational work cost. We find that optimal designs always saturate the bound
on the erasing time requirement, but can exceed the required reliability time
if critically damped. The non-trivial geometry of the reliability and erasing
time-scales allows us to exclude large regions of parameter space as
sub-optimal. We find that optimal designs are either critically damped or close
to critical damping under the erasing procedure.",1702.04950v2
2017-02-16,Effects of Landau damping on ion-acoustic solitary waves in a semiclassical plasma,"We study the nonlinear propagation of ion-acoustic waves (IAWs) in an
unmagnetized collisionless plasma with the effects of electron and ion Landau
damping in the weak quantum (semiclassical) regime, i.e., when the typical
ion-acoustic (IA) length scale is larger than the thermal de Broglie
wavelength. Starting from a set of classical and semiclassical Vlasov equations
for ions and electrons, coupled to the Poisson equation, we derive a modified
(by the particle dispersion) Korteweg-de Vries (KdV) equation which governs the
evolution of IAWs with the effects of wave-particle resonance. It is found that
in contrast to the classical results, the nonlinear IAW speed $(\lambda)$ and
the linear Landau damping rate $(\gamma)$ are no longer constants, but can vary
with the wave number $(k)$ due to the quantum particle dispersion. The effects
of the quantum parameter $H$ (the ratio of the plasmon energy to the thermal
energy) and the electron to ion temperature ratio $(T)$ on the profiles of
$\lambda$, $\gamma$ and the solitary wave amplitude are also studied. It is
shown that the decay rate of the wave amplitude is reduced by the effects of
$H$.",1702.05035v2
2017-03-07,Higgs Modes in the Pair Density Wave Superconducting State,"The pair density wave (PDW) superconducting state has been proposed to
explain the layer- decoupling effect observed in the compound
La$_{2-x}$Ba$_x$CuO$_4$ at $x=1/8$ (Phys. Rev. Lett. 99, 127003). In this state
the superconducting order parameter is spatially modulated, in contrast with
the usual superconducting (SC) state where the order parameter is uniform. In
this work, we study the properties of the amplitude (Higgs) modes in a
unidirectional PDW state. To this end we consider a phenomenological model of
PDW type states coupled to a Fermi surface of fermionic quasiparticles. In
contrast to conventional superconductors that have a single Higgs mode,
unidirectional PDW superconductors have two Higgs modes. While in the PDW state
the Fermi surface largely remains gapless, we find that the damping of the PDW
Higgs modes into fermionic quasiparticles requires exceeding an energy
threshold. We show that this suppression of damping in the PDW state is due to
kinematics. As a result, only one of the two Higgs modes is significantly
damped. In addition, motivated by the experimental phase diagram, we discuss
the mixing of Higgs modes in the coexistence regime of the PDW and uniform SC
states. These results should be observable directly in a Raman spectroscopy, in
momentum resolved electron energy loss spectroscopy, and in resonant inelastic
X-ray scattering, thus providing evidence of the PDW states.",1703.02541v2
2017-08-16,Effects of group velocity and multi-plasmon resonances on the modulation of Langmuir waves in a degenerate plasma,"We study the nonlinear wave modulation of Langmuir waves (LWs) in a fully
degenerate plasma. Using the Wigner-Moyal equation coupled to the Poisson
equation and the multiple scale expansion technique, a modified nonlocal
nonlinear Schr{\""{o}}dinger (NLS) equation is derived which governs the
evolution of LW envelopes in degenerate plasmas. The nonlocal nonlinearity in
the NLS equation appears due to the group velocity and multi-plasmon
resonances, i.e., resonances induced by the simultaneous particle absorption of
multiple wave quanta. We focus on the regime where the resonant velocity of
electrons is larger than the Fermi velocity and thereby the linear Landau
damping is forbidden. As a result, the nonlinear wave-particle resonances due
to the group velocity and multi-plasmon processes are the dominant mechanisms
for wave-particle interaction. It is found that in contrast to classical or
semiclassical plasmas, the group velocity resonance does not necessarily give
rise the wave damping in the strong quantum regime where $ \hbar k\sim mv_{F}$
with $\hbar$ denoting the reduced Planck's constant, $m$ the electron mass and
$v_F$ the Fermi velocity, however, the three-plasmon process plays a dominant
role in the nonlinear Landau damping of wave envelopes. In this regime, the
decay rate of the wave amplitude is also found to be higher compared to that in
the modest quantum regime where the multi-plasmon effects are forbidden.",1708.04965v3
2018-04-11,Axial quasi-normal modes of neutron stars in $R^2$ gravity,"In the present paper the axial quasi-normal modes of neutron stars in $f(R)$
gravity are examined using a large set of equations of state. The numerical
calculations are made using two different approaches -- performing time
evolution of the perturbation equations and solving the time-independent
representation of the equations as a boundary value problem. According to the
results the mode frequencies and the damping times decrease with the increase
of the free parameter of the theory in comparison to the pure general
relativistic case. While the frequencies deviate significantly from Einstein's
theory for all realistic neutron star masses (say above $1M_\odot$), the
damping times reach non-negligible differences only for the more massive
models. We have constructed as well universal (equation of state independent)
gravitational wave asteroseismology relations involving the frequencies and the
damping times. It turns out that the equation of state independence is
preserved using the same normalization as in pure general relativity and the
qualitative differences of the phenomenological relations with respect to
Einstein's theory of gravity can be large for large values of the free
parameter in $f(R)$ gravity.",1804.04060v1
2018-11-14,Anderson-Bogoliubov and Carlson-Goldman modes in counterflow superconductors: Case study of a double monolayer graphene,"The impact of electron-hole pairing on the spectrum of plasma excitations in
double layer systems is investigated. The theory is developed with reference to
a double monolayer graphene. Taking into account the coupling of scalar
potential oscillations with oscillations of the order parameter $\Delta$, we
show that the spectrum of antisymmetric (acoustic) plasma excitations contains
two modes: a weakly damped mode below the gap $2\Delta$ and a strongly damped
mode above the gap. The lower mode can be interpreted as an analog of the
Carlson-Goldman mode. This mode has an acoustic dispersion relation at small
wave vectors and it saturates at the level $2\Delta$ at large wave vectors. Its
velocity is larger than the velocity of the Anderson-Bogoliubov mode
$v_{AB}=v_F$/$\sqrt{2}$, and it can be smaller than the Fermi velocity $v_F$.
The damping rate of this mode strongly increases under increase of temperature.
Out-of-phase oscillations of two order parameters in two spin subsystems are
also considered. This part of the spectrum contains two more modes. One of them
is interpreted as an analog of the Anderson-Bogoliubov (phase) mode and the
other, as an analog of the Schmid (amplitude) mode. With minor modifications
the theory can be extended to describe collective modes in a double bilayer
graphene as well.",1811.05899v3
2019-05-09,An excess of excesses examined via dark matter radio emissions from galaxies,"Cosmic-ray and gamma-ray observations have yielded several notable excesses
that often lend themselves to explanation by various dark matter
annihilation/decay models. In particular, the AMS-02 anti-proton and positron
excesses have continued to grow more robust with the collection of more data.
This is supplemented by gamma-ray excesses in the Galactic Centre and a
high-energy break in spectrum of electron/positron cosmic rays seen by DAMPE.
In this work we carefully model the magnetic field environments of M31 and M33
and use this to estimate expected synchrotron emissions from electrons produced
via dark matter annihilation. By comparing this to available radio data we
review simplifying assumptions used previously for dark matter hunting in these
environments and produce novel constraints that are capable of fully ruling out
dark matter models proposed to accommodate all the aforementioned excesses
barring that of DAMPE. However, we do show that significant constraints can be
placed upon the DAMPE parameter space with M31 data. In addition to this we
project SKA non-observation constraints for the Reticulum II and Triangulum II
dwarf galaxies and find these have potential to rule out cosmic-ray and
gamma-ray excess-producing models of dark matter, even when the most
conservative assumptions are employed.",1905.05599v5
2019-05-17,Statics and Dynamics of Polymeric Droplets on Chemically Homogeneous and Heterogeneous Substrates,"We present a molecular dynamics study of the motion of cylindrical polymer
droplets on striped surfaces. We first consider the equilibrium properties of
droplets on different surfaces, we show that for small stripes the
Cassie-Baxter equation gives a good approximation of the equilibrium contact
angle. As the stripe width becomes non-negligible compared to the dimension of
the droplets, the droplet has to deform significantly to minimize its free
energy, this results in a smaller value of the contact angle than the continuum
model predicts. We then evaluate the slip length, and thus the damping
coefficient as a function of the stripe width. For very small stripes, the
heterogeneous surface behaves as an effective surface, with the same damping as
an homogeneous surface with the same contact angle. However, as the stripe
width increases, damping at the surface increases until reaching a plateau.
Afterwards, we study the dynamics of droplets under a bulk force. We show that
if the stripes are large enough the droplets are pinned until a critical
acceleration. The critical acceleration increases linearly with stripe width.
For large enough accelerations, the average velocity increases linearly with
the acceleration, we show that it can then be predicted by a model depending
only the size of droplet, viscosity and slip length. We show that the velocity
of the droplet varies sinusoidally as a function of its position on the
substrate. On the other hand, for accelerations just above the depinning
acceleration we observe a characteristic stick-slip motion, with successive
pinnings and depinnings.",1905.07214v1
2019-05-20,"Exploring the damping of Alfvén waves along a long off-limb coronal loop, up to 1.4 R$_\odot$","The Alfv\'en wave energy flux in the corona can be explored using the
electron density and velocity amplitude of the waves. The velocity amplitude of
Alfv\'en waves can be obtained from the non-thermal velocity of the spectral
line profiles. Previous calculations of the Alfv\'en wave energy flux with
height in active regions and polar coronal holes have provided evidence for the
damping of Alfv\'en waves with height. We present off-limb Hinode EUV imaging
spectrometer (EIS) observations of a long coronal loop up to 1.4~R$_\odot$. We
have obtained the electron density along the loop and found the loop to be
almost in hydrostatic equilibrium. We obtained the temperature using the
EM-loci method and found the loop to be isothermal across, as well as along,
the loop with a temperature of about 1.37 MK. We significantly improve the
estimate of non-thermal velocities over previous studies by using the estimated
ion (equal to electron) temperature. Estimates of electron densities are
improved using the significant updates of the CHIANTI v.8 atomic data. More
accurate measurements of propagating Alfv\'en wave energy along the coronal
loop and its damping are presented up to distances of 1.4 R$_\odot$, further
than have been previously explored. The Alfv\'en wave energy flux obtained
could contribute to a significant part of the coronal losses due to radiation
along the loop.",1905.08194v2
2020-07-15,On the Extension of Linear Damping to Quantum Mechanics through Fractionary Momentum Operators Pt. I,"The use of fractional momentum operators and fractionary kinetic energy used
to model linear damping in dissipative systems such as resistive circuits and a
spring-mass ensambles was extended to a quantum mechanical formalism. Three
important associated 1 dimensional problems were solved: the free particle
case, the infinite potential well, and the harmonic potential. The wave
equations generated reproduced the same type of 2-order ODE observed in
classical dissipative systems, and produced quantized energy levels. In the
infinite potential well, a zero-point energy emerges, which can be fitted to
the rest energy of the particle described by special relativity, given by
relationship $E_r=mc^2$. In the harmonic potential, new fractional creation and
destruction operators were introduced to solve the problem in the energy basis.
The energy eigenvalues found are different to the ones reported by earlier
approaches to the quantum damped oscillator problem reported by other authors.
In this case, a direct relationship between the relativistic rest energy of the
particle and the expected value of the fractionary kinetic energy in the base
state was obtained. We conclude that there exists a relationship between
fractional kinetic energy and special relativity energies, that remains unclear
and needs further exploration, but also conclude that the current form of
transforming fractionary momentum operators to the position basis will yield
non-observable imaginary momentum quantities, and thus a correction to the way
of transforming them needs to be explored further.",2007.07434v3
2020-07-18,Results from the Alfvén Eigenmode Active Diagnostic during the 2019-2020 JET deuterium campaign,"This paper presents results of extensive analysis of mode excitation observed
during the operation of the Alfv\'{e}n Eigenmode Active Diagnostic (AEAD) in
the JET tokamak during the 2019-2020 deuterium campaign. Six of eight
toroidally spaced antennas, each with independent power and phasing, were
successful in actively exciting stable MHD modes in 479 plasmas. In total, 4768
magnetic resonances were detected with up to fourteen fast magnetic probes. In
this work, we present the calculations of resonant frequencies $f_0$, damping
rates $\gamma < 0$, and toroidal mode numbers $n$, spanning the parameter range
$f_0 \approx$ 30 - 250 kHz, $-\gamma \approx$ 0 - 13 kHz, and $\vert n \vert
\leq 30$. In general, good agreement is seen between the resonant and the
calculated toroidal Alfv\'{e}n Eigenmode frequencies, and between the toroidal
mode numbers applied by the AEAD and estimated of the excited resonances. We
note several trends in the database: the probability of resonance detection
decreases with plasma current and external heating power; the normalized
damping rate increases with edge safety factor but decreases with external
heating. These results provide key information to prepare future experimental
campaigns and to better understand the physics of excitation and damping of
Alfv\'{e}n Eigenmodes in the presence of alpha particles during the upcoming DT
campaign, thereby extrapolating with confidence to future tokamaks.",2007.09412v1
2013-08-17,Thickness and power dependence of the spin-pumping effect in Y3Fe5O12/Pt heterostructures measured by the inverse spin Hall effect,"The dependence of the spin-pumping effect on the yttrium iron garnet
(Y3Fe5O12, YIG) thickness detected by the inverse spin Hall effect (ISHE) has
been investigated quantitatively. Due to the spin-pumping effect driven by the
magnetization precession in the ferrimagnetic insulator YIG film a
spin-polarized electron current is injected into the Pt layer. This spin
current is transformed into electrical charge current by means of the ISHE. An
increase of the ISHE-voltage with increasing film thickness is observed and
compared to the theoretically expected behavior. The effective damping
parameter of the YIG/Pt samples is found to be enhanced with decreasing YIG
film thickness. The investigated samples exhibit a spin mixing conductance of
g=(7.43 \pm 0.36) \times 10^{18} m^{-2} and a spin Hall angle of theta_{ISHE} =
0.009 \pm 0.0008. Furthermore, the influence of nonlinear effects on the
generated voltage and on the Gilbert damping parameter at high excitation
powers are revealed. It is shown that for small YIG film thicknesses a
broadening of the linewidth due to nonlinear effects at high excitation powers
is suppressed because of a lack of nonlinear multi-magnon scattering channels.
We have found that the variation of the spin-pumping efficiency for thick YIG
samples exhibiting pronounced nonlinear effects is much smaller than the
nonlinear enhancement of the damping.",1308.3787v1
2014-03-12,Enhancing robustness of multiparty quantum correlations using weak measurement,"Multipartite quantum correlations are important resources for the development
of quantum information and computation protocols. However, the resourcefulness
of multipartite quantum correlations in practical settings is limited by its
fragility under decoherence due to environmental interactions. Though there
exist protocols to protect bipartite entanglement under decoherence, the
implementation of such protocols for multipartite quantum correlations has not
been sufficiently explored. Here, we study the effect of local amplitude
damping channel on the generalized Greenberger-Horne-Zeilinger state, and use a
protocol of optimal reversal quantum weak measurement to protect the
multipartite quantum correlations. We observe that the weak measurement
reversal protocol enhances the robustness of multipartite quantum correlations.
Further it increases the critical damping value that corresponds to
entanglement sudden death. To emphasize the efficacy of the technique in
protection of multipartite quantum correlation, we investigate two proximately
related quantum communication tasks, namely, quantum teleportation in a one
sender, many receivers setting and multiparty quantum information splitting,
through a local amplitude damping channel. We observe an increase in the
average fidelity of both the quantum communication tasks under the weak
measurement reversal protocol. The method may prove beneficial, for combating
external interactions, in other quantum information tasks using multipartite
resources.",1403.2939v1
2016-11-29,Dissipative self-gravitating Bose-Einstein condensates with arbitrary nonlinearity as a model of dark matter halos,"We develop a general formalism applying to Newtonian self-gravitating
Bose-Einstein condensates. This formalism may find application in the context
of dark matter halos. We introduce a generalized Gross-Pitaevskii equation
including a source of dissipation (damping) and an arbitrary nonlinearity.
Using the Madelung transformation, we derive the hydrodynamic representation of
this generalized Gross-Pitaevskii equation and obtain a damped quantum Euler
equation involving a friction force proportional and opposite to the velocity
and a pressure force associated with an equation of state determined by the
nonlinearity present in the generalized Gross-Pitaevskii equation. In the
strong friction limit, we obtain a quantum Smoluchowski equation. These
equations satisfy an $H$-theorem for a free energy functional constructed with
a generalized entropy. We specifically consider the Boltzmann and Tsallis
entropies associated with isothermal and polytropic equations of state. We also
consider the entropy associated with the logotropic equation of state. We
derive the virial theorem corresponding to the generalized Gross-Pitaevskii
equation, damped quantum Euler equation, and quantum Smoluchowski equation.
Using a Gaussian ansatz, we obtain a simple equation governing the dynamical
evolution of the size of the condensate. We highlight a specific model of dark
matter halos corresponding to a generalized Gross-Pitaevskii equation with a
logarithmic nonlinearity and a cubic nonlinearity. It leads to dark matter
halos with an equation of state $P=\rho k_B T_{\rm eff}/m+2\pi
a_s\hbar^2\rho^{2}/m^3$ presenting a condensed core (BEC/soliton) and an
isothermal halo with an effective temperature $T_{\rm eff}$. We propose that
this model provides an effective coarse-grained parametrization of dark matter
halos experiencing gravitational cooling.",1611.09610v1
2017-01-03,A Model for Dissipation of Solar Wind Magnetic Turbulence by Kinetic Alfvén Waves at Electron Scales: Comparison with Observations,"In hydrodynamic turbulence, it is well established that the length of the
dissipation scale depends on the energy cascade rate, i.e., the larger the
energy input rate per unit mass, the more the turbulent fluctuations need to be
driven to increasingly smaller scales to dissipate the larger energy flux.
Observations of magnetic spectral energy densities indicate that this intuitive
picture is not valid in solar wind turbulence. Dissipation seems to set in at
the same length scale for different solar wind conditions independently of the
energy flux. To investigate this difference in more detail, we present an
analytic dissipation model for solar wind turbulence at electron scales, which
we compare with observed spectral densities. Our model combines the energy
transport from large to small scales and collisionless damping, which removes
energy from the magnetic fluctuations in the kinetic regime. We assume
wave-particle interactions of kinetic Alfv\'{e}n waves (KAW) to be the main
damping process. Wave frequencies and damping rates of KAW are obtained from
the hot plasma dispersion relation. Our model assumes a critically balanced
turbulence, where larger energy cascade rates excite larger parallel
wavenumbers for a certain perpendicular wavenumber. If the dissipation is
additionally wave driven such that the dissipation rate is proportional to the
parallel wavenumber - as with KAW - then an increase of the energy cascade rate
is counter-balanced by an increased dissipation rate for the same perpendicular
wavenumber leading to a dissipation length independent of the energy cascade
rate.",1701.00680v1
2018-05-10,Dust modification of the plasma conductivity in the mesosphere,"Relative transverse drift (with respect to the ambient magnetic field)
between the weakly magnetized electrons and the unmagnetized ions at the lower
altitude (80 km) and between the weakly magnetized ions and unmagnetized dust
at the higher altitude (90 km) gives rise to the finite Hall conductivity in
the Earth's mesosphere. If, on the other hand, the number of free electrons is
sparse in the mesosphere and most of the negative charge resides on the weakly
magnetized, fine, nanometre sized dust powder and positive charge on the more
massive, micron sized, unmagnetized dust, the sign of the Hall conductivity due
to their relative transverse drift will be opposite to the previous case. Thus
the sign of the Hall effect not only depends on the direction of the local
magnetic field but also on the nature of the charge carrier in the partially
ionized dusty medium.
  As the Hall and the Ohm diffusion are comparable below 80 km, the low
frequency long wavelength waves will be damped at this altitude with the
damping rate typically of the order of few minutes. Therefore, the ultra--low
frequency magnetohydrodynamic waves can not originate below 80 km in the
mesosphere. However, above 80 km since Hall effect dominates Ohm diffusion the
mesosphere can host the ultra--low frequency waves which can propagate across
the ionosphere with little or, no damping.",1805.03799v1
2018-05-19,Migration of Planets Into and Out of Mean Motion Resonances in Protoplanetary Discs: Overstability of Capture and Nonlinear Eccentricity Damping,"A number of multiplanet systems are observed to contain planets very close to
mean motion resonances, although there is no significant pileup of precise
resonance pairs. We present theoretical and numerical studies on the outcome of
capture into first-order mean motion resonances (MMRs) using a parametrized
planet migration model that takes into account nonlinear eccentricity damping
due to planet-disk interaction. This parametrization is based on numerical
hydrodynamical simulations and is more realistic than the simple linear
parametrization widely used in previous analytic studies. We find that
nonlinear eccentricity damping can significantly influence the stability and
outcome of resonance capture. In particular, the equilibrium eccentricity of
the planet captured into MMRs become larger, and the captured MMR state tends
to be more stable compared to the prediction based on the simple migration
model. In addition, when the migration is sufficiently fast or/and the planet
mass ratio is sufficiently small, we observe a novel phenomenon of eccentricity
overshoot, where the planet's eccentricity becomes very large before settling
down to the lower equilibrium value. This can lead to the ejection of the
smaller planet if its eccentricity approaches unity during the overshoot. This
may help explain the lack of low-mass planet companion of hot Jupiters when
compared to warm Jupiters.",1805.07501v1
2001-07-19,Dipole Wakefield Suppression In High Phase Advance Detuned Linear Accelerators For The JLC/NLC Designed To Minimise Electrical Breakdown And Cumulative BBU,"Recent experiments at SLAC [1,2] and CERN [3] have revealed evidence of
significant deformation in the form of ""pitting"" of the cells of the 1.8m
series of structures DDS/RDDS (Damped Detuned Structure/Rounded Damped Detuned
Structure). This pitting occurs in the high group velocity (vg /c = 0.012) end
of the accelerating structure and little evidence of breakdown has been found
in the lower group velocity end of the structure. Additional, albeit
preliminary experimental evidence, suggests that shorter and lower group
velocity structures have reduced breakdown events with increasing accelerating
field strengths. Two designs are presented here, firstly a 90cm structure
consisting of 83 cells with an initial vg/c = 0.0506 (known as H90VG5) and
secondly, an even shorter structure of length 60cm consisting of 55 cells with
an initial vg /c = 0.03 (known as H60VG3). The feasibility of using these
structures to accelerate a charged beam over 10km is investigated. The
particular issue focussed upon is suppression of the dipole wakefields via
detuning of the cell frequencies and by locally damping individual cells in
order to avoid BBU (Beam Break Up). Results are presented on beam-induced
dipole wakefields and on the beam dynamics encountered on tracking the progress
of the beam through several thousand accelerating structures.
  [1] C. Adolphsen, ROAA003, this conf. [2] R.H. Miller et al, FPAH062, this
conf. [3] L. Groening et al, MPPH039, this conf",0107049v1
2011-11-06,The various manifestations of collisionless dissipation in wave propagation,"The propagation of an electrostatic wave packet inside a collisionless and
initially Maxwellian plasma is always dissipative because of the irreversible
acceleration of the electrons by the wave. Then, in the linear regime, the wave
packet is Landau damped, so that in the reference frame moving at the group
velocity, the wave amplitude decays exponentially with time. In the nonlinear
regime, once phase mixing has occurred and when the electron motion is nearly
adiabatic, the damping rate is strongly reduced compared to the Landau one, so
that the wave amplitude remains nearly constant along the characteristics. Yet,
we show here that the electrons are still globally accelerated by the wave
packet, and, in one dimension, this leads to a non local amplitude dependence
of the group velocity. As a result, a freely propagating wave packet would
shrink, and, therefore, so would its total energy. In more than one dimension,
not only does the magnitude of the group velocity nonlinearly vary, but also
its direction. In the weakly nonlinear regime, when the collisionless damping
rate is still significant compared to its linear value, this leads to an
effective defocussing effect which we quantify, and which we compare to the
self-focussing induced by wave front bowing.",1111.1391v2
2011-11-15,Spin waves in nanosized magnetic films,"We have studied spin excitations in nanosized magnetic films in the
Heisenberg model with magnetic dipole and exchange interactions by the spin
operator diagram technique. Dispersion relations of spin waves in thin magnetic
films (in two-dimensional magnetic monolayers and in two-layer magnetic films)
and the spin-wave resonance spectrum in N-layer structures are found. For thick
magnetic films generalized Landau-Lifshitz equations are derived from first
principles. Landau-Lifshitz equations have the integral (pseudodifferential)
form, but not differential one. Spin excitations are determined by simultaneous
solution of the Landau-Lifshitz equations and the equation for the
magnetostatic potential. For normal magnetized ferromagnetic films the spin
wave damping has been calculated in the one-loop approximation for a diagram
expansion of the Green functions at low temperature. In thick magnetic films
the magnetic dipole interaction makes a major contribution to the relaxation of
long-wavelength spin waves. Thin films have a region of low relaxation of
long-wavelength spin waves. In thin magnetic films four-spin-wave processes
take place and the exchange interaction makes a major contribution to the
damping. It is found that the damping of spin waves propagating in magnetic
monolayer is proportional to the quadratic dependence on the temperature and is
very low for spin waves with small wavevectors. Spin-wave devices on the base
of nanosized magnetic films are proposed -- tunable narrow-band spin-wave
filters with high quality at the microwave frequency range and field-effect
transistor (FET) structures contained nanosized magnetic films under the gate
electrode. Spin-wave resonances in nanosized magnetic films can be used to
construct FET structures operating in Gigahertz and Terahertz frequency bands.",1111.3532v1
2012-01-23,PageRank and rank-reversal dependence on the damping factor,"PageRank (PR) is an algorithm originally developed by Google to evaluate the
importance of web pages. Considering how deeply rooted Google's PR algorithm is
to gathering relevant information or to the success of modern businesses, the
question of rank-stability and choice of the damping factor (a parameter in the
algorithm) is clearly important. We investigate PR as a function of the damping
factor d on a network obtained from a domain of the World Wide Web, finding
that rank-reversal happens frequently over a broad range of PR (and of d). We
use three different correlation measures, Pearson, Spearman, and Kendall, to
study rank-reversal as d changes, and show that the correlation of PR vectors
drops rapidly as d changes from its frequently cited value, $d_0=0.85$.
Rank-reversal is also observed by measuring the Spearman and Kendall rank
correlation, which evaluate relative ranks rather than absolute PR.
Rank-reversal happens not only in directed networks containing rank-sinks but
also in a single strongly connected component, which by definition does not
contain any sinks. We relate rank-reversals to rank-pockets and bottlenecks in
the directed network structure. For the network studied, the relative rank is
more stable by our measures around $d=0.65$ than at $d=d_0$.",1201.4787v1
2012-04-20,The Stability of Massive Main Sequence Stars as a Function of Metallicity,"We investigate the pulsational stability of massive (M >~ 120 Msun) main
sequence stars of a range of metallicities, including primordial, Population
III stars. We include a formulation of convective damping motivated by
numerical simulations of the interaction between convection and periodic shear
flows. We find that convective viscosity is likely strong enough to stabilize
radial pulsations whenever nuclear-burning (the epsilon-mechanism) is the
dominant source of driving. This suggests that massive main sequence stars with
Z <~ 2 x 10^-3 are pulsationally stable and are unlikely to experience
pulsation-driven mass loss on the main sequence. These conclusions are,
however, sensitive to the form of the convective viscosity and highlight the
need for further high-resolution simulations of the convection-oscillation
interaction. For more metal-rich stars (Z >~ 2 x 10^-3), the dominant
pulsational driving arises due to the kappa-mechanism arising from the
iron-bump in opacity and is strong enough to overcome convective damping. Our
results highlight that even for oscillations with periods a few orders of
magnitude shorter than the outer convective turnover time, the ""frozen-in""
approximation for the convection-oscillation interaction is inappropriate, and
convective damping should be taken into account when assessing mode stability.",1204.4741v1
2013-09-13,Analytical and experimental stability investigation of a hardware-in-the-loop satellite docking simulator,"The European Proximity Operation Simulator (EPOS) of the DLR-German Aerospace
Center is a robotics-based simulator that aims at validating and verifying a
satellite docking phase. The generic concept features a robotics tracking
system working in closed loop with a force/torque feedback signal. Inherent
delays in the tracking system combined with typical high stiffness at contact
challenge the stability of the closed-loop system. The proposed concept of
operations is hybrid: the feedback signal is a superposition of a measured
value and of a virtual value that can be tuned in order to guarantee a desired
behavior. This paper is concerned with an analytical study of the system's
closed-loop stability, and with an experimental validation of the hybrid
concept of operations in one dimension (1D). The robotics simulator is modeled
as a second-order loop-delay system and closed-form expressions for the
critical delay and associated frequency are derived as a function of the
satellites' mass and the contact dynamics stiffness and damping parameters. A
numerical illustration sheds light on the impact of the parameters on the
stability regions. A first-order Pade approximation provides additional means
of stability investigation. Experiments were performed and tests results are
described for varying values of the mass and the damping coefficients. The
empirical determination of instability is based on the coefficient of
restitution and on the observed energy. There is a very good agreement between
the critical damping values predicted by the analysis and observed during the
tests...",1309.3512v1
2014-05-19,"Comparison of micromagnetic parameters of ferromagnetic semiconductors (Ga,Mn)(As,P) and (Ga,Mn)As","We report on the determination of micromagnetic parameters of epilayers of
the ferromagnetic semiconductor (Ga,Mn)As, which has easy axis in the sample
plane, and (Ga,Mn)(As,P) which has easy axis perpendicular to the sample plane.
We use an optical analog of ferromagnetic resonance where the
laser-pulse-induced precession of magnetization is measured directly in the
time domain. By the analysis of a single set of pump-and-probe magneto-optical
data we determined the magnetic anisotropy fields, the spin stiffness and the
Gilbert damping constant in these two materials. We show that incorporation of
10% of phosphorus in (Ga,Mn)As with 6% of manganese leads not only to the
expected sign change of the perpendicular to plane anisotropy field but also to
an increase of the Gilbert damping and to a reduction of the spin stiffness.
The observed changes in the micromagnetic parameters upon incorporating P in
(Ga,Mn)As are consistent with the reduced hole density, conductivity, and Curie
temperature of the (Ga,Mn)(As,P) material. We report that the magnetization
precession damping is stronger for the n = 1 spin wave resonance mode than for
the n = 0 uniform magnetization precession mode.",1405.4677v1
2014-06-04,Constraints on the gas masses of low-z damped Lyman-$α$ systems,"We report a deep search for redshifted HI 21 cm emission from three damped
and sub-damped Lyman-$\alpha$ absorbers (DLAs) at $z \approx 0.1$ with the
Green Bank Telescope (GBT). No evidence for a redshifted HI 21 cm emission
signal was obtained in the GBT spectra of two absorbers, with the data on the
third rendered unusable by terrestrial interference. The non-detections of HI
21 cm emission yield strong constraints on the HI masses of the associated
galaxies, M$_{\rm HI} < 2.3 \times 10^9 \times (\Delta V/100)^{1/2}$ M$_\odot$
for the sub-DLA at $z = 0.0830$ towards J1553+3548, and M$_{\rm HI} < 2.7
\times 10^9 \times (\Delta V/100)^{1/2}$ M$_\odot$ for the DLA at $z = 0.0963$
towards J1619+3342, where $\Delta V$ is the HI 21 cm line width, in km
s$^{-1}$. This continues the trend of low HI masses found in all low-$z$ DLAs
and sub-DLAs that have been searched for redshifted HI 21 cm emission.
Low-redshift absorbers with relatively low HI column densities, $\lesssim few
\times 10^{20}$ cm$^{-2}$, thus do not typically arise in massive gas-rich
galaxies.",1406.0991v2
2014-06-09,Evolution of eccentricity and orbital inclination of migrating planets in 2:1 mean motion resonance,"We determine, analytically and numerically, the conditions needed for a
system of two migrating planets trapped in a 2:1 mean motion resonance to enter
an inclination-type resonance. We provide an expression for the asymptotic
equilibrium value that the eccentricity $e_{\rm i}$ of the inner planet reaches
under the combined effects of migration and eccentricity damping. We also show
that, for a ratio $q$ of inner to outer masses below unity, $e_{\rm i}$ has to
pass through a value $e_{\rm i,res}$ of order 0.3 for the system to enter an
inclination-type resonance. Numerically, we confirm that such a resonance may
also be excited at another, larger, value $e_{\rm i, res} \simeq 0.6$, as found
by previous authors. A necessary condition for onset of an inclination-type
resonance is that the asymptotic equilibrium value of $e_{\rm i}$ is larger
than $e_{\rm i,res}$. We find that, for $q \le 1$, the system cannot enter an
inclination-type resonance if the ratio of eccentricity to semimajor axis
damping timescales $t_e/t_a$ is smaller than 0.2. This result still holds if
only the eccentricity of the outer planet is damped and $q \lesssim 1$. As the
disc/planet interaction is characterized by $t_e/t_a \sim 10^{-2}$, we conclude
that excitation of inclination through the type of resonance described here is
very unlikely to happen in a system of two planets migrating in a disc.",1406.2189v1
2014-06-13,Magnetic-Field Amplification in the Thin X-ray Rims of SN1006,"Several young supernova remnants (SNRs), including SN1006, emit synchrotron
X-rays in narrow filaments, hereafter thin rims, along their periphery. The
widths of these rims imply 50 to 100 $\mu$G fields in the region immediately
behind the shock, far larger than expected for the interstellar medium
compressed by unmodified shocks, assuming electron radiative losses limit rim
widths. However, magnetic-field damping could also produce thin rims. Here we
review the literature on rim width calculations, summarizing the case for
magnetic-field amplification. We extend these calculations to include an
arbitrary power-law dependence of the diffusion coefficient on energy, $D
\propto E^{\mu}$. Loss-limited rim widths should shrink with increasing photon
energy, while magnetic-damping models predict widths almost independent of
photon energy. We use these results to analyze Chandra observations of SN 1006,
in particular the southwest limb. We parameterize the full widths at half
maximum (FWHM) in terms of energy as FWHM $\propto E^{m_E}_{\gamma}$. Filament
widths in SN1006 decrease with energy; $m_E \sim -0.3$ to $-0.8$, implying
magnetic field amplification by factors of 10 to 50, above the factor of 4
expected in strong unmodified shocks. For SN 1006, the rapid shrinkage rules
out magnetic damping models. It also favors short mean free paths (small
diffusion coefficients) and strong dependence of $D$ on energy ($\mu \ge 1$).",1406.3630v2
2015-12-15,Correlations between compositions and orbits established by the giant impact era of planet formation,"The giant impact phase of terrestrial planet formation establishes
connections between super-Earths' orbital properties (semimajor axis spacings,
eccentricities, mutual inclinations) and interior compositions (the presence or
absence of gaseous envelopes). Using N-body simulations and analytic arguments,
we show that spacings derive not only from eccentricities, but also from
inclinations. Flatter systems attain tighter spacings, a consequence of an
eccentricity equilibrium between gravitational scatterings, which increase
eccentricities, and mergers, which damp them. Dynamical friction by residual
disk gas plays a critical role in regulating mergers and in damping
inclinations and eccentricities. Systems with moderate gas damping and high
solid surface density spawn gas-enveloped super-Earths with tight spacings,
small eccentricities, and small inclinations. Systems in which super-Earths
coagulate without as much ambient gas, in disks with low solid surface density,
produce rocky planets with wider spacings, larger eccentricities, and larger
mutual inclinations. A combination of both populations can reproduce the
observed distributions of spacings, period ratios, transiting planet
multiplicities, and transit duration ratios exhibited by Kepler super-Earths.
The two populations, both formed in situ, also help to explain observed trends
of eccentricity vs. planet size, and bulk density vs. method of mass
measurement (radial velocities vs. transit timing variations). Simplifications
made in this study --- including the limited timespan of the simulations, and
the approximate treatments of gas dynamical friction and gas depletion history
--- should be improved upon in future work to enable a detailed quantitative
comparison to the observations.",1512.04951v2
2015-12-18,Seismic waves damping with arrays of inertial resonators,"We investigate the elastic stop band properties of a theoretical cubic array
of iron spheres connected to a bulk of concrete via iron or rubber ligaments.
Each sphere can move freely within a surrounding air cavity, but ligaments
couple it to the bulk and further facilitate bending and rotational motions.
Associated low frequency local resonances are well predicted by an asymptotic
formula. We find complete stop bands (for all wave-polarizations) in the
frequency range $[16,21]$ Hertz (resp. $[6,11]$ Hertz) for $7.4$-meter (resp.
$0.74$-meter) diameter iron spheres with a $10$-meter (resp. $1$-meter)
center-to-center spacing, when they are connected to concrete via steel (resp.
rubber) ligaments. The scattering problem shows that only bending modes are
responsible for damping and that rotational modes are totally overwritten by
bending modes. Regarding seismic applications, we further consider soil as a
bulk medium, in which case the relative bandwidth of the low frequency stop
band can be enlarged through ligaments of different sizes that allow for well
separated bending and rotational modes. We finally achieve some damping of
elastodynamic waves from $8$ to $49$ Hertz (relative stop band of $143$
percent) for iron spheres $0.74$-meter in diameter that are connected to soil
with six rubber ligaments of optimized shapes. These results represent a
preliminary step in the design of seismic shields placed around, or underneath,
the foundations of large civil infrastructures.",1512.06078v2
2016-05-05,Electromagnetic fields in the exterior of an oscillating relativistic star -- II. Electromagnetic damping,"An important issue in the asteroseismology of compact and magnetized stars is
the determination of the dissipation mechanism which is most efficient in
damping the oscillations when these are produced. In a linear regime and for
low-multipolarity modes these mechanisms are confined to either
gravitational-wave or electromagnetic losses. We here consider the latter and
compute the energy losses in the form of Poynting fluxes, Joule heating and
Ohmic dissipation in a relativistic oscillating spherical star with a dipolar
magnetic field in vacuum. While this approach is not particularly realistic for
rapidly rotating stars, it has the advantage that it is fully analytic and that
it provides expressions for the electric and magnetic fields produced by the
most common modes of oscillation both in the vicinity of the star and far away
from it. In this way we revisit and extend to a relativistic context the
classical estimates of McDermott et al. Overall, we find that
general-relativistic corrections lead to electromagnetic damping time-scales
that are at least one order of magnitude smaller than in Newtonian gravity.
Furthermore, with the only exception of $g$ (gravity) modes, we find that $f$
(fundamental), $p$ (pressure), $i$ (interface) and $s$ (shear) modes are
suppressed more efficiently by gravitational losses than by electromagnetic
ones.",1605.01709v1
2016-05-22,Low Gilbert damping in Co2FeSi and Fe2CoSi films,"Thin highly textured Fe$_{\mathrm{1+x}}$Co$_{\mathrm{2-x}}$Si ($0 \leq$ x
$\leq 1$) films were prepared on MgO (001) substrates by magnetron
co-sputtering. The magneto-optic Kerr effect (MOKE) and ferromagnetic resonance
(FMR) measurements were used to investigate the composition dependence of the
magnetization, the magnetic anisotropy, the gyromagnetic ratio and the
relaxation of the films. The effective magnetization for the thin
Fe$_{\mathrm{1+x}}$Co$_{\mathrm{2-x}}$Si films, determined by FMR measurements,
are consistent with the Slater Pauling prediction. Both MOKE and FMR
measurements reveal a pronounced fourfold anisotropy distribution for all
films. In addition we found a strong influence of the stoichiometry on the
anisotropy as the cubic anisotropy strongly increases with increasing Fe
concentration. The gyromagnetic ratio is only weakly dependent on the
composition. We find low Gilbert damping parameters for all films with values
down to $0.0012\pm0.00012$ for Fe$_{1.75}$Co$_{1.25}$Si. The effective damping
parameter for Co$_2$FeSi is found to be $0.0018\pm 0.0004$. We also find a
pronounced anisotropic relaxation, which indicates significant contributions of
two-magnon scattering processes that is strongest along the easy axes of the
films. This makes thin Fe$_{\mathrm{1+x}}$Co$_{\mathrm{2-x}}$Si films ideal
materials for the application in STT-MRAM devices.",1605.06797v1
2016-12-06,Breakdown of Fermi liquid theory in topological multi-Weyl semimetals,"Fermi liquid theory works very well in most normal metals, but is found
violated in many strongly correlated electron systems, such as cuprate and
heavy-fermion superconductors. A widely accepted criterion is that, the Fermi
liquid theory is valid when the interaction-induced fermion damping rate
approaches zero more rapidly than the energy. Otherwise, it is invalid. Here,
we demonstrate that this criterion breaks down in topological double-and
triple-Weyl semimetals. Renormalization group analysis reveals that, although
the damping rate of double- and triple-Weyl fermions induced by the Coulomb
interaction approaches zero more rapidly than the energy, the quasiparticle
residue vanishes and the Fermi liquid theory is invalid. This behavior
indicates a weaker-than-marginal violation of the Fermi liquid theory. Such an
unconventional non-Fermi liquid state originates from the special dispersion of
double- and triple-Weyl fermions, and is qualitatively different from all the
other Fermi-liquid and non-Fermi-liquid states. The predicted properties of the
fermion damping rate and the spectral function can be probed by the
angle-resolved photoemission spectroscopy. The density of states, specific
heat, and conductivities are also calculated and analyzed after incorporating
the corrections induced by the Coulomb interaction.",1612.01729v2
2016-12-08,Quantifying acoustic damping using flame chemiluminescence,"Thermoacoustic instabilities in gas turbines and aeroengine combustors falls
within the category of complex systems. They can be described
phenomenologically using nonlinear stochastic differential equations, which
constitute the grounds for output-only model-based system identification. It
has been shown recently that one can extract the governing parameters of the
instabilities, namely the linear growth rate and the nonlinear component of the
thermoacoustic feedback, using dynamic pressure time series only. This is
highly relevant for practical systems, which cannot be actively controlled due
to a lack of cost-effective actuators. The thermoacoustic stability is given by
the linear growth rate, which results from the combination of the acoustic
damping and the coherent feedback from the flame. In this paper, it is shown
that it is possible to quantify the acoustic damping of the system, and thus to
separate its contribution to the linear growth rate from the one of the flame.
This is achieved by post-processing in a simple way simultaneously acquired
chemiluminescence and acoustic pressure data. It provides an additional
approach to further unravel from observed time series the key mechanisms
governing the system dynamics. This straightforward method is illustrated here
using experimental data from a combustion chamber operated at several linearly
stable and unstable operating conditions.",1612.02609v1
2016-12-29,A quasi-mode theory of chiral phonons,"The coherence properties of mechanical resonators are often limited by
multiple unavoidable forms of loss -- including phonon-phonon and phonon-defect
scattering -- which result in the scattering of sound into other resonant modes
and into the phonon bath. Dynamic suppression of this scattering loss can lift
constraints on device structure and can improve tolerance to defects in the
material, even after fabrication. Inspired by recent experiments, here we
introduce a model of phonon losses resulting from disorder in a whispering
gallery mode resonator with acousto-optical coupling between optical and
mechanical modes. We show that a typical elastic scattering mechanism of high
quality factor (Q) mechanical modes flips the direction of phonon propagation
via high-angle scattering, leading to damping into modes with the opposite
parity. When the optical mode overlaps co-propagating high-Q and bulk
mechanical modes, the addition of laser cooling via sideband-resolved damping
of the mechanical mode of a chosen parity also damps and modifies the response
of the bulk modes of the same parity. This, in turn, simultaneously improves
the quality factor and reduces the thermal load of the counter-propagating
high-Q modes, leading to the dynamical creation of a cold phononic shield. We
compare our theoretical results to the recent experiments of Kim et al., and
find quantitative agreement with our theory.",1612.09240v1
2017-06-16,Challenges testing the no-hair theorem with gravitational waves,"General relativity's no-hair theorem states that isolated astrophysical black
holes are described by only two numbers: mass and spin. As a consequence, there
are strict relationships between the frequency and damping time of the
different modes of a perturbed Kerr black hole. Testing the no-hair theorem has
been a longstanding goal of gravitational-wave astronomy. The recent detection
of gravitational waves from black hole mergers would seem to make such tests
imminent. We investigate how constraints on black hole ringdown parameters
scale with the loudness of the ringdown signal---subject to the constraint that
the post-merger remnant must be allowed to settle into a perturbative,
Kerr-like state. In particular, we require that---for a given detector---the
gravitational waveform predicted by numerical relativity is indistinguishable
from an exponentially damped sine after time $t^\text{cut}$. By requiring the
post-merger remnant to settle into such a perturbative state, we find that
confidence intervals for ringdown parameters do not necessarily shrink with
louder signals. In at least some cases, more sensitive measurements probe later
times without necessarily providing tighter constraints on ringdown frequencies
and damping times. Preliminary investigations are unable to explain this result
in terms of a numerical relativity artifact.",1706.05152v2
2017-06-26,Simulating the effect of high column density absorbers on the one-dimensional Lyman-alpha forest flux power spectrum,"We measure the effect of high column density absorbing systems of neutral
hydrogen (HI) on the one-dimensional (1D) Lyman-alpha forest flux power
spectrum using cosmological hydrodynamical simulations from the Illustris
project. High column density absorbers (which we define to be those with HI
column densities $N(\mathrm{HI}) > 1.6 \times
10^{17}\,\mathrm{atoms}\,\mathrm{cm}^{-2}$) cause broadened absorption lines
with characteristic damping wings. These damping wings bias the 1D Lyman-alpha
forest flux power spectrum by causing absorption in quasar spectra away from
the location of the absorber itself. We investigate the effect of high column
density absorbers on the Lyman-alpha forest using hydrodynamical simulations
for the first time. We provide templates as a function of column density and
redshift, allowing the flexibility to accurately model residual contamination,
i.e., if an analysis selectively clips out the largest damping wings. This
flexibility will improve cosmological parameter estimation, e.g., allowing more
accurate measurement of the shape of the power spectrum, with implications for
cosmological models containing massive neutrinos or a running of the spectral
index. We provide fitting functions to reproduce these results so that they can
be incorporated straightforwardly into a data analysis pipeline.",1706.08532v2
2017-07-19,Engineering elliptical spin-excitations by complex anisotropy fields in Fe adatoms and dimers on Cu(111),"We investigate the dynamics of Fe adatoms and dimers deposited on the Cu(111)
metallic surface in the presence of spin-orbit coupling, within time-dependent
density functional theory. The \textit{ab initio} results provide
material-dependent parameters that can be used in semiclassical approaches,
which are used for insightful interpretations of the excitation modes. By
manipulating the surroundings of the magnetic elements, we show that elliptical
precessional motion may be induced through the modification of the magnetic
anisotropy energy. We also demonstrate how different kinds of spin precession
are realized, considering the symmetry of the magnetic anisotropy energy, the
ferro- or antiferromagnetic nature of the exchange coupling between the
impurities, and the strength of the magnetic damping. In particular, the normal
modes of a dimer depend on the initial magnetic configuration, changing
drastically by going from a ferromagnetic metastable state to the
antiferromagnetic ground state. By taking into account the effect of the
damping into their resonant frequencies, we reveal that an important
contribution arises for strongly biaxial systems and specially for the
antiferromagnetic dimers with large exchange couplings. Counter intuitively,
our results indicate that the magnetic damping influences the quantum
fluctuations by decreasing the zero-point energy of the system.",1707.06087v2
2017-10-02,The gas and stellar mass of low-redshift damped Lyman-$α$ absorbers,"We report Hubble Space Telescope Cosmic Origins Spectrograph far-ultraviolet
and Arecibo Telescope H{\sc i} 21cm spectroscopic studies of six damped and
sub-damped Lyman-$\alpha$ absorbers (DLAs and sub-DLAs, respectively) at $z
\lesssim 0.1$, that have yielded estimates of their H{\sc i} column density,
metallicity and atomic gas mass. This significantly increases the number of
DLAs with gas mass estimates, allowing the first comparison between the gas
masses of DLAs and local galaxies. Including three absorbers from the
literature, we obtain H{\sc i} masses $\approx (0.24 - 5.2) \times 10^9 \: {\rm
M}_\odot$, lower than the knee of the local H{\sc i} mass function. This
implies that massive galaxies do not dominate the absorption cross-section for
low-$z$ DLAs. We use Sloan Digital Sky Survey photometry and spectroscopy to
identify the likely hosts of four absorbers, obtaining low stellar masses,
$\approx 10^7-10^{8.7} M_\odot$, in all cases, consistent with the hosts being
dwarf galaxies. We obtain high H{\sc i} 21\,cm or CO emission line widths,
$\Delta V_{20} \approx 100-290$~km~s$^{-1}$, and high gas fractions, $f_{\rm
HI} \approx 5-100$, suggesting that the absorber hosts are gas-rich galaxies
with low star formation efficiencies. However, the H{\sc i} 21\,cm velocity
spreads ($\gtrsim 100$~km~s$^{-1}$) appear systematically larger than the
velocity spreads in typical dwarf galaxies.",1710.00710v1
2017-10-25,Two-Level System Damping in a Quasi-One-Dimensional Optomechanical Resonator,"Nanomechanical resonators have demonstrated great potential for use as
versatile tools in a number of emerging quantum technologies. For such
applications, the performance of these systems is restricted by the decoherence
of their fragile quantum states, necessitating a thorough understanding of
their dissipative coupling to the surrounding environment. In bulk amorphous
solids, these dissipation channels are dominated at low temperatures by
parasitic coupling to intrinsic two-level system (TLS) defects, however, there
remains a disconnect between theory and experiment on how this damping
manifests in dimensionally-reduced nanomechanical resonators. Here, we present
an optomechanically-mediated thermal ringdown technique, which we use to
perform simultaneous measurements of the dissipation in four mechanical modes
of a cryogenically-cooled silicon nanoresonator, with resonant frequencies
ranging from 3 - 19 MHz. Analyzing the device's mechanical damping rate at
fridge temperatures between 10 mK - 10 K, we demonstrate quantitative agreement
with the standard tunneling model for TLS ensembles confined to one dimension.
From these fits, we extract the defect density of states ($P_0 \sim$ 1 - 4
$\times$ 10$^{44}$ J$^{-1}$ m$^{-3}$) and deformation potentials ($\gamma \sim$
1 - 2 eV), showing that each mechanical mode couples on average to less than a
single thermally-active defect at 10 mK.",1710.09439v3
2017-12-07,Flavor Structure of the Cosmic-Ray Electron/Positron Excesses at DAMPE,"The Dark Matter Particle Explorer (DAMPE) satellite detector announced its
first result for measuring the cosmic-ray electron/positron (CRE) energy
spectrum up to 4.6TeV, including a tentative peak-like event excess at
(1.3-1.5)TeV. In this work, we uncover a significant hidden excess in the DAMPE
CRE spectrum over the energy range (0.6-1.1)TeV, which has a non-peak-like
structure. We propose a new mechanism to explain this excess by a set of 1.5TeV
$\mu^\pm$ events with subsequent decays into $e^\pm$ plus neutrinos. For
explaining this new excess together with the peak excess around 1.4TeV, we
demonstrate that the {\it flavor structure} of the original lepton final-state
produced by dark matter (DM) annihilations (or other mechanism) should have a
composition ratio $N_e : (N_\mu +\frac{1}{6}N_\tau) = 1 : y$, with $y \simeq
2.6-10.8$. For lepton portal DM models, this puts important constraint on the
lepton-DM-mediator couplings $\lambda_e : (\lambda_\mu^4 +
\frac{1}{6}\lambda_\tau^4)^{\frac{1}{4}} = 1 : y^{\frac{1}{4}}$ with a narrow
range $y^{\frac{1}{4}} \simeq 1.3-1.8$.",1712.02744v3
2017-12-20,Unifying ultrafast demagnetization and intrinsic Gilbert damping in Co/Ni bilayers with electronic relaxation near the Fermi surface,"The ability to controllably manipulate the laser-induced ultrafast magnetic
dynamics is a prerequisite for future high speed spintronic devices. The
optimization of devices requires the controllability of the ultrafast
demagnetization time, , and intrinsic Gilbert damping, . In previous attempts
to establish the relationship between and , the rare-earth doping of a
permalloy film with two different demagnetization mechanism is not a suitable
candidate. Here, we choose Co/Ni bilayers to investigate the relations between
and by means of time-resolved magneto-optical Kerr effect (TRMOKE) via
adjusting the thickness of the Ni layers, and obtain an approximately
proportional relation between these two parameters. The remarkable agreement
between TRMOKE experiment and the prediction of breathing Fermi-surface model
confirms that a large Elliott-Yafet spin-mixing parameter is relevant to the
strong spin-orbital coupling at the Co/Ni interface. More importantly, a
proportional relation between and in such metallic films or heterostructures
with electronic relaxation near Fermi surface suggests the local spin-flip
scattering domains the mechanism of ultrafast demagnetization, otherwise the
spin-current mechanism domains. It is an effective method to distinguish the
dominant contributions to ultrafast magnetic quenching in metallic
heterostructures by investigating both the ultrafast demagnetization time and
Gilbert damping simultaneously. Our work can open a novel avenue to manipulate
the magnitude and efficiency of Terahertz emission in metallic heterostructures
such as the perpendicular magnetic anisotropic Ta/Pt/Co/Ni/Pt/Ta multilayers,
and then it has an immediate implication of the design of high frequency
spintronic devices.",1712.07323v1
2017-12-22,Low-momentum dynamic structure factor of a strongly interacting Fermi gas at finite temperature: A two-fluid hydrodynamic description,"We provide a description of the dynamic structure factor of a homogeneous
unitary Fermi gas at low momentum and low frequency, based on the dissipative
two-fluid hydrodynamic theory. The viscous relaxation time is estimated and is
used to determine the regime where the hydrodynamic theory is applicable and to
understand the nature of sound waves in the density response near the
superfluid phase transition. By collecting the best knowledge on the shear
viscosity and thermal conductivity known so far, we calculate the various
diffusion coefficients and obtain the damping width of the (first and second)
sounds. We find that the damping width of the first sound is greatly enhanced
across the superfluid transition and very close to the transition the second
sound might be resolved in the density response for the transferred momentum up
to the half of Fermi momentum. Our work is motivated by the recent measurement
of the local dynamic structure factor at low momentum at Swinburne University
of Technology and the on-going experiment on sound attenuation of a homogeneous
unitary Fermi gas at Massachusetts Institute of Technology. We discuss how the
measurement of the velocity and damping width of the sound modes in
low-momentum dynamic structure factor may lead to an improved determination of
the universal superfluid density, shear viscosity and thermal conductivity of a
unitary Fermi gas.",1712.08320v1
2018-01-15,Amplitude- and gas pressure-dependent nonlinear damping of high-Q oscillatory MEMS micro mirrors,"Silicon-based micro-electromechanical systems (MEMS) can be fabricated using
bulk and surface micromachining technology. A micro mirror designed as an
oscillatory MEMS constitutes a prominent example. Typically, in order to
minimize energy consumption, the micro mirror is designed to have high quality
factors. In addition, a phase-locked loop guarantees resonant actuation despite
the occurrence of frequency shifts. In these cases, the oscillation amplitude
of the micro mirror is expected to scale linearly with the actuation input
power. Here, however, we report on an experimental observation which clearly
shows an amplitude depletion that is not in accordance with any linear
behaviour. As a consequence, the actuation forces needed to reach the desired
oscillation amplitude are by multiples higher than expected. We are able to
explain the experimental observations accurately by introducing a single
degree-of-freedom model including an amplitude-dependent nonlinear damping
term. Remarkably, we find that the nonlinear damping shows a clear gas pressure
dependency. We investigate the concepts and compare our findings on two
different micro mirror design layouts.",1801.04758v2
2018-01-30,Model Based Active Slosh Damping Experiment,"This paper presents a model based experimental investigation to demonstrate
the usefulness of an active damping strategy to manage fluid sloshing motion in
spacecraft tanks. The active damping strategy is designed to reduce the
degrading impact on maneuvering and pointing performance via a force feedback
strategy. Many problems have been encountered until now, such as instability of
the closed loop system, excessive consumption in the attitude propellant or
problems for engine re-ignition in upper stages. Mostly, they have been
addressed in a passive way via the design of baffles and membranes, which on
their own have mass and constructive impacts. Active management of propellant
motion in launchers and satellites has the potential to increase performance on
various levels. This paper demonstrates active slosh management using force
feedback for the compensation of the slosh resonances. Force sensors between
tank and the carrying structure provide information of the fluid motion via the
reaction force. The control system is designed to generate an appropriate
acceleration profile that leads to desired attenuation profiles in amplitude,
frequency and time. Two robust control design methods, one based on $\mu$
design and the other on parametric structured design based on non-smooth
optimization of the worst-case $H_{\infty}$ norm, are applied. The controller
is first tested with a computational fluid dynamics simulation in the loop.
Finally a water tank mounted on a Hexapod with up to $1100$ liter is used to
evaluate the control performance. The paper illustrates that is possible to
actively influence sloshing via closed loop.",1801.10017v1
2018-09-06,Forming Gliese 876 Through Smooth Disk Migration,"We run a suite of dissipative N-body simulations to determine which regions
of phase space for smooth disk migration are consistent with the GJ876 system,
an M-dwarf hosting three planets orbiting in a chaotic 4:2:1 Laplace resonance.
We adopt adaptive mesh refinement (AMR) methods which are commonly used in
hydrodynamical simulations to efficiently explore the parameter space defined
by the semi-major axis and eccentricity damping timescales. We find that there
is a large region of phase space which produces systems in the chaotic Laplace
resonance and a smaller region consistent with the observed eccentricities and
libration amplitudes for the resonant angles. Under the assumptions of Type I
migration for the outer planet, we translate these damping timescales into
constraints on the protoplanetary disk surface density and thickness. When we
strongly (weakly) damp the eccentricities of the inner two Laplace planets,
these timescales correspond to disk surface densities around ten thousand (a
few hundred) grams per square centimeter and disk aspect ratios between 1-10%.
Additionally, smooth migration produces systems with a range of chaotic
timescales, from decades and centuries to upwards of thousands of years. In
agreement with previous studies, the less chaotic regions of phase space
coincide with the system being in a low energy double apsidal corotation
resonance. Our detailed modeling of multi-planetary systems coupled with our
AMR exploration method enhances our ability to map out the parameter space of
planet formation models, and is well suited to study other resonant chain
systems such as Trappist-1, Kepler-60, and others.",1809.02200v2
2018-09-15,New closures for more precise modeling of Landau damping in the fluid framework,"Incorporation of kinetic effects such as Landau damping into a fluid
framework was pioneered by Hammett and Perkins PRL 1990, by obtaining closures
of the fluid hierarchy, where the gyrotropic heat flux fluctuations or the
deviation of the 4th-order gyrotropic fluid moment, are expressed through
lower-order fluid moments. To obtain a closure of a fluid model expanded around
a bi-Maxwellian distribution function, the usual plasma dispersion function
$Z(\zeta)$ that appears in kinetic theory or the associated plasma response
function $R(\zeta)=1 + \zeta Z(\zeta)$, have to be approximated with a suitable
Pad\'e approximant in such a way, that the closure is valid for all $\zeta$
values. Such closures are rare, and the original closures of Hammett and
Perkins are often employed. Here we present a complete mapping of all plausible
Landau fluid closures that can be constructed at the level of 4th-order moments
in the gyrotropic limit and we identify the most precise closures. Furthermore,
by considering 1D closures at higher-order moments, we show that it is possible
to reproduce linear Landau damping in the fluid framework to any desired
precision, thus showing convergence of the fluid and collisionless kinetic
descriptions.",1809.05718v1
2018-10-04,Sub-photospheric turbulence as a heating mechanism in gamma-ray bursts,"We examine the possible role of turbulence in feeding the emission of
gamma-ray bursts (GRBs). Turbulence may develop in a GRB jet as the result of
hydrodynamic or current-driven instabilities. The jet carries dense radiation
and the turbulence cascade can be damped by Compton drag, passing kinetic fluid
energy to photons through scattering. We identify two regimes of turbulence
dissipation: (1) ""Viscous"" - the turbulence cascade is Compton damped on a
scale $\ell_{\rm damp}$ greater than the photon mean free path $\ell_\star$.
Then turbulence energy is passed to photons via bulk Comptonization by smooth
shear flows on scale $\ell_\star<\ell_{\rm damp}$. (2) ""Collisionless"" - the
cascade avoids Compton damping and extends to microscopic plasma scales much
smaller than $\ell_\star$. The collisionless dissipation energizes plasma
particles, which radiate the received energy; how the dissipated power is
partitioned between particles needs further investigation with kinetic
simulations. We show that the dissipation regime switches from viscous to
collisionless during the jet expansion, at a critical value of the jet optical
depth which depends on the amplitude of turbulence. Turbulent GRB jets are
expected to emit nonthermal photospheric radiation. Our analysis also suggests
revisions of turbulent Comptonization in black hole accretion disks discussed
in previous works.",1810.02228v1
2018-10-15,Zombie Vortex Instability. III. Persistence with Nonuniform Stratification and Radiative Damping,"The Zombie Vortex Instability (ZVI) occurs in the dead zones of
protoplanetary disks (PPDs) where perturbations excite baroclinic critical
layers, generating ""zombie"" vortices and turbulence. In this work, we
investigate ZVI with nonuniform vertical stratification; while ZVI is triggered
in the stratified regions away from the midplane, the subsequent turbulence
propagates into and fills the midplane. ZVI turbulence alters the background
Keplerian shear flow, creating a steady-state zonal flow. Intermittency is
observed, where the flow cycles through near-laminar phases of zonal flow
punctuated by chaotic bursts of new vortices. ZVI persists in the presence of
radiative damping, as long as the thermal relaxation timescale is more than a
few orbital periods. We refute the premature claim by Lesur & Latter (2016)
that radiative damping inhibits ZVI for disk radii r>0.3 au. Their conclusions
were based on unrealistically short cooling times using opacities with
virtually no grain growth. We explore different grain growth and vertical
settling scenarios, and find that the gas and dust in off-midplane regions are
not necessarily in local thermodynamic equilibrium (LTE) with each other. In
such cases, thermal relaxation timescales can be orders of magnitude longer
than the optically thin cooling times assuming LTE because of the finite time
for energy to be exchanged between gas and dust grains via collisions. With
minimal amounts of grain growth and dust settling, the off-midplane regions of
disks are susceptible to ZVI and much of the planet-forming regions can be
filled with zombie vortices and turbulence.",1810.06588v1
2018-09-21,High performance passive vibration isolation system for optical tables using six-degree-of-freedom viscous damping combined with steel springs,"Mechanical vibrations in buildings are ubiquitous. Such vibrations limit the
performance of sensitive instruments used, for example, for high-precision
manufacturing, nanofabrication, metrology, medical systems, or microscopy. For
improved precision, instruments and optical tables need to be isolated from
mechanical vibrations. However, common active or passive vibration isolation
systems often perform poorly when low-frequency vibration isolation is required
or are expensive. Furthermore, a simple solution such as suspension from common
bungee cords may require high ceilings. Here we developed a vibration isolation
system that uses steel springs to suspend an optical table from a common-height
ceiling. The system was designed for a fundamental resonance frequency of 0.5
Hz. Resonances and vibrations were efficiently damped in all translational and
rotational degrees of freedom of the optical table by spheres, which were
mounted underneath the table and immersed in a highly viscous silicone oil. Our
low-cost, passive system outperformed several state-of-the-art passive and
active systems in particular in the frequency range between 1-10 Hz. We
attribute this performance to a minimal coupling between the degrees of freedom
and the truly three dimensional viscous damping combined with a nonlinear
hydrodynamic finite-size effect. Furthermore, the system can be adapted to
different loads, resonance frequencies, and dimensions. In the long term, the
excellent performance of the system will allow high-precision measurements for
many different instruments.",1810.06641v4
2018-10-17,Resonance-broadened transit time damping of particles in MHD turbulence,"As a fundamental astrophysical process, the scattering of particles by
turbulent magnetic fields has its physical foundation laid by the
magnetohydrodynamic (MHD) turbulence theory. In the framework of the modern
theory of MHD turbulence, we derive a generalized broadened resonance function
by taking into account both the magnetic fluctuations and nonlinear
decorrelation of turbulent magnetic fields arising in MHD turbulence, and we
specify the energy range of particles for the dominance of different broadening
mechanisms. The broadened resonance allows for scattering of particles beyond
the energy threshold of the linear resonance. By analytically determining the
pitch-angle diffusion coefficients for transit time damping (TTD) with slow and
fast modes, we demonstrate that the turbulence anisotropy of slow modes
suppresses their scattering efficiency. Furthermore, we quantify the dependence
of the relative importance between slow and fast modes in TTD scattering on (i)
particle energy, (ii) plasma $\beta$ (the ratio of gas pressure to magnetic
pressure), and (iii) damping of MHD turbulence, and we also provide the
parameter space for the dominance of slow modes. To exemplify its applications,
we find that among typical partially ionized interstellar phases, in the warm
neutral medium slow and fast modes have comparable efficiencies in TTD
scattering of cosmic rays. For low-energy particles, e.g., sub-Alfv\'{e}nic
charged grains, we show that slow modes always dominate TTD scattering.",1810.07726v1
2018-10-23,Calibration of the DAMPE Plastic Scintillator Detector and its on-orbit performance,"DArk Matter Particle Explorer (DAMPE) is a space-borne apparatus for
detecting the high-energy cosmic-rays like electrons, $\gamma$-rays, protons
and heavy-ions. Plastic Scintillator Detector (PSD) is the top-most
sub-detector of the DAMPE. The PSD is designed to measure the charge of
incident high-energy particles and it also serves as a veto detector for
discriminating $\gamma$-rays from charged particles. In this paper, PSD
on-orbit calibration procedure is described, which includes five steps of
pedestal, dynode correlation, response to minimum-ionizing particles (MIPs),
light attenuation function and energy reconstruction. A method for
reconstructing the charge of incident high energy cosmic-ray particles is
introduced. The detection efficiency of each PSD strip is verified to be above
99.5%, the total efficiency of the PSD for charged particles is above 99.99%.",1810.09901v1
2018-10-25,Charge Measurement of Cosmic Ray Nuclei with the Plastic Scintillator Detector of DAMPE,"One of the main purposes of the DArk Matter Particle Explorer (DAMPE) is to
measure the cosmic ray nuclei up to several tens of TeV or beyond, whose origin
and propagation remains a hot topic in astrophysics. The Plastic Scintillator
Detector (PSD) on top of DAMPE is designed to measure the charges of cosmic ray
nuclei from H to Fe and serves as a veto detector for discriminating gamma-rays
from charged particles. We propose in this paper a charge reconstruction
procedure to optimize the PSD performance in charge measurement. Essentials of
our approach, including track finding, alignment of PSD, light attenuation
correction, quenching and equalization correction are described detailedly in
this paper after a brief description of the structure and operational principle
of the PSD. Our results show that the PSD works very well and almost all the
elements in cosmic rays from H to Fe are clearly identified in the charge
spectrum.",1810.10784v1
2019-06-14,Influence of External Magnetic Field on Dust$-$Acoustic Waves in a Capacitive RF Discharge,"This paper reports experiments on self$-$excited dust acoustic waves (DAWs)
and its propagation characteristics in a magnetized rf discharge plasma. The
DAWs are spontaneously excited in dusty plasma after adding more particles in
the confining potential well and found to propagate in the direction of
streaming ions. The spontaneous excitation of such low-frequency modes is
possible due to the instabilities associated with streaming ions through the
dust grain medium. The background E-field and neutral pressure determine the
stability of excited DAWs. The characteristics of DAWs strongly depend on the
strength of external magnetic field. The magnetic field of strength B $<$ 0.05
T only modifies the characteristics of propagating waves in dusty plasma at
moderate power and pressure, P = 3.5 W and p = 27 Pa respectively. It is found
that DAWs start to be damped with increasing the magnetic field beyond B $>$
0.05 T and get completely damped at higher magnetic field B $\sim$ 0.13 T.
After lowering the power and pressure to 3 W and 23 Pa respectively, the
excited DAWs in the absence of B are slightly unstable. In this case, the
magnetic field only stabilizes and modifies the propagation characteristics of
DAWs while the strength of B is increased up to 0.1 T or even higher. The
modification of the sheath electric field where particles are confined in the
presence of the external magnetic field is the main cause of the modification
and damping of the DAWs in a magnetized rf discharge plasma.",1906.06255v2
2019-06-18,A Dynamic Robotic Actuator with Variable Physical Stiffness and Damping,"This study is part of research aiming at increasing the range of dynamic
tasks for teleoperated field robotics in order to allow operators to use the
full range of human motions without being limited by the dynamics of the
robotic manipulator. A new variable impedance actuator (VIA) was designed,
capable of reproducing motions through teleoperation from precise positioning
tasks to highly dynamic tasks. The design requirements based on previous human
user studies were a stiffness changing time of 50 ms, a peak output velocity of
20 rad/s and variable damping allowing to suppress undesired oscillations. This
is a unique combination of features that was not met by other VIAs. The new
design has three motors in parallel configuration: two responsible for changing
the VIA's neutral position and effective stiffness through a sliding pivot
point lever mechanism, and the third acting as variable damper. A prototype was
built and its performance measured with an effective stiffness changing time of
50 to 120 ms for small to large stiffness steps, nominal output velocity of 16
rad/s and a variable damper with a damping torque from 0 to 3 Nm. Its effective
stiffness range is 0.2 to 313 Nm/rad. This concludes that the new actuator is
particularly suitable for highly dynamic tasks. At the same time, the new
actuator is also very versatile, making it especially interesting for
teleoperation and human-robot collaboration.",1906.07669v2
2019-06-27,Frequency Fluctuations in Tunable and Nonlinear Microwave Cavities,"We present a model for how frequency fluctuations comparable to the total
cavity linewidth may arise in tunable and nonlinear microwave cavities, and how
these fluctuations affect the measurement of scattering matrix elements.
Applying this model to the specific case of a two-sided cavity, we obtain
closed-form expressions for the average scattering matrix elements in several
important cases. A key signature of our model is the subtle deformation of the
trajectories swept out by scattering matrix elements in the complex plane.
Despite this signature, the fluctuating and non-fluctuating models are
qualitatively similar enough to be mistaken for one another. In the case of
tunable cavities we show that if one fails to account for these fluctuations
then one will find damping rates that appear to depend on the tuning parameter,
which is a common observation in such systems. In the case of a Kerr cavity, we
show that there exists a fundamental lower bound to the scale of these
frequency fluctuations in the steady state, imposed by quantum mechanical
uncertainty, which can appreciably affect the apparent damping rates of the
cavity as the strength of the nonlinearity approaches the single-photon level.
By using the model we present as a fitting function for experimental data,
however, one can extract both the true damping rates of the cavity and the
effective scale of these frequency fluctuations over the scattering
measurement's bandwidth. Lastly, we compare this new method for observing
frequency fluctuations to other methods, one of which we extend beyond the
regime of small fluctuations.",1906.11989v3
2019-09-16,Inviscid damping and enhanced dissipation of the boundary layer for 2D Navier-Stokes linearized around Couette flow in a channel,"We study the 2D Navier-Stokes equations linearized around the Couette flow
$(y,0)^t$ in the periodic channel $\mathbb T \times [-1,1]$ with no-slip
boundary conditions in the vanishing viscosity $\nu \to 0$ limit. We split the
vorticity evolution into the free evolution (without a boundary) and a boundary
corrector that is exponentially localized to at most an $O(\nu^{1/3})$ boundary
layer. If the initial vorticity perturbation is supported away from the
boundary, we show inviscid damping of both the velocity and the vorticity
associated to the boundary layer. For example, our $L^2_t L^1_y$ estimate of
the boundary layer vorticity is independent of $\nu$, provided the initial data
is $H^1$. For $L^2$ data, the loss is only logarithmic in $\nu$. Note both such
estimates are false for the vorticity in the interior. To the authors'
knowledge, this inviscid decay of the boundary layer vorticity seems to be a
new observation not previously isolated in the literature. Both velocity and
vorticity satisfy the expected $O(\exp(-\delta\nu^{1/3}\alpha^{2/3}t))$
enhanced dissipation in addition to the inviscid damping. Similar, but slightly
weaker, results are obtained also for $H^1$ data that is against the boundary
initially. For $L^2$ data against the boundary, we at least obtain the boundary
layer localization and enhanced dissipation.",1909.07230v1
2019-10-19,Anomalies in the switching dynamics of C-type antiferromagnets and antiferromagnetic nanowires,"Antiferromagnets (AFMs) are widely believed to be superior than ferromagnets
in spintronics because of their high stability due to the vanishingly small
stray field. It is thus expected that the order parameter of AFM should always
align along the easy-axis of the crystalline anisotropy. In contrast to this
conventional wisdom, we find that the AFM order parameter switches away from
the easy-axis below a critical anisotropy strength when an AFM is properly
tailored into a nano-structure. The switching time first decreases and then
increases with the damping. Above the critical anisotropy, the AFM order
parameter is stable and precesses under a microwave excitation. However, the
absorption peak is not at resonance frequency even for magnetic damping as low
as 0.01. To resolve these anomalies, we first ascertain the hidden role of
dipolar interaction that reconstructs the energy landscape of the nano-system
and propose a model of damped non-linear pendulum to explain the switching
behavior. In this framework, the second anomaly appears when an AFM is close to
the boundary between underdamped and overdamped phases, where the observed
absorption lineshape has small quality factor and thus is not reliable any
longer. Our results should be significant to extract the magnetic parameters
through resonance techniques.",1910.08668v1
2020-01-13,Modelling Stochastic Signatures in Classical Pulsators,"We consider the impact of stochastic perturbations on otherwise coherent
oscillations of classical pulsators. The resulting dynamics are modelled by a
driven damped harmonic oscillator subject to either an external or an internal
forcing and white noise velocity fluctuations. We characterize the phase and
relative amplitude variations using analytical and numerical tools. When the
forcing is internal the phase variation displays a random walk behaviour and a
red noise power spectrum with a ragged erratic appearance. We determine the
dependence of the root mean square phase and relative amplitude variations
($\sigma_{\Delta \varphi}$ and $\sigma_{\Delta A/A}$, respectively) on the
amplitude of the stochastic perturbations, the damping constant $\eta$, and the
total observation time $t_{\rm obs}$ for this case, under the assumption that
the relative amplitude variations remain small, showing that $\sigma_{\Delta
\varphi}$ increases with $t_{\rm obs}^{1/2}$ becoming much larger than
$\sigma_{\Delta A/A}$ for $t_{\rm obs} \gg \eta^{-1}$. In the case of an
external forcing the phase and relative amplitude variations remain of the same
order, independent of the observing time. In the case of an internal forcing,
we find that $\sigma_{\Delta \varphi}$ does not depend on $\eta$. Hence, the
damping time cannot be inferred from fitting the power of the signal, as done
for solar-like pulsators, but the amplitude of the stochastic perturbations may
be constrained from the observations. Our results imply that, given sufficient
time, the variation of the phase associated to the stochastic perturbations in
internally driven classical pulsators will become sufficiently large to be
probed observationally.",2001.04558v1
2020-01-23,Skyrmion Dynamics and Topological Sorting on Periodic Obstacle Arrays,"We examine skyrmions under a dc drive interacting with a square array of
obstacles for varied obstacle size and damping. When the drive is applied in a
fixed direction, we find that the skyrmions are initially guided in the drive
direction but also move transverse to the drive due to the Magnus force. The
skyrmion Hall angle, which indicates the difference between the skyrmion
direction of motion and the drive direction, increases with drive in a series
of quantized steps as a result of the locking of the skyrmion motion to
specific symmetry directions of the obstacle array. On these steps, the
skyrmions collide with an integer number of obstacles to create a periodic
motion. The transitions between the different locking steps are associated with
jumps or dips in the velocity-force curves. In some regimes, the skyrmion Hall
angle is actually higher than the intrinsic skyrmion Hall angle that would
appear in the absence of obstacles. In the limit of zero damping, the skyrmion
Hall angle is 90$^\circ$, and we find that it decreases as the damping
increases. For multiple interacting skyrmion species in the collective regime,
we find jammed behavior at low drives where the different skyrmion species are
strongly coupled and move in the same direction. As the drive increases, the
species decouple and each can lock to a different symmetry direction of the
obstacle lattice, making it possible to perform topological sorting in analogy
to the particle sorting methods used to fractionate different species of
colloidal particles moving over two-dimensional obstacle arrays.",2001.08835v1
2020-12-08,"Meta Learning-based MIMO Detectors: Design, Simulation, and Experimental Test","Deep neural networks (NNs) have exhibited considerable potential for
efficiently balancing the performance and complexity of multiple-input and
multiple-output (MIMO) detectors. We propose a receiver framework that enables
efficient online training by leveraging the following simple observation:
although NN parameters should adapt to channels, not all of them are
channel-sensitive. In particular, we use a deep unfolded NN structure that
represents iterative algorithms in signal detection and channel decoding
modules as multi layer deep feed forward networks. An expectation propagation
(EP) module, called EPNet, is established for signal detection by unfolding the
EP algorithm and rendering the damping factors trainable. An unfolded turbo
decoding module, called TurboNet, is used for channel decoding. This component
decodes the turbo code, where trainable NN units are integrated into the
traditional max-log-maximum a posteriori decoding procedure. We demonstrate
that TurboNet is robust for channels and requires only one off-line training.
Therefore, only a few damping factors in EPNet must be re-optimized online. An
online training mechanism based on meta learning is then developed. Here, the
optimizer, which is implemented by long short-term memory NNs, is trained to
update damping factors efficiently by using a small training set such that they
can quickly adapt to new environments. Simulation results indicate that the
proposed receiver significantly outperforms traditional receivers and that the
online learning mechanism can quickly adapt to new environments. Furthermore,
an over-the-air platform is presented to demonstrate the significant robustness
of the proposed receiver in practical deployment.",2012.04379v1
2020-12-31,Adaptive Surgical Robotic Training Using Real-Time Stylistic Behavior Feedback Through Haptic Cues,"Surgical skill directly affects surgical procedure outcomes; thus, effective
training is needed to ensure satisfactory results. Many objective assessment
metrics have been developed and some are widely used in surgical training
simulators. These objective metrics provide the trainee with descriptive
feedback about their performance however, often lack feedback on how to proceed
to improve performance. The most effective training method is one that is
intuitive, easy to understand, personalized to the user and provided in a
timely manner. We propose a framework to enable user-adaptive training using
near-real-time detection of performance, based on intuitive styles of surgical
movements (e.g., fluidity, smoothness, crispness, etc.), and propose a haptic
feedback framework to assist with correcting styles of movement. We evaluate
the ability of three types of force feedback (spring, damping, and spring plus
damping feedback), computed based on prior user positions, to improve different
stylistic behaviors of the user during kinematically constrained reaching
movement tasks. The results indicate that four out of the six styles studied
here were statistically significantly improved (p<0.05) using spring guidance
force feedback and a significant reduction in task time was also found using
spring feedback. The path straightness and targeting error in the task were
other task performance metrics studied which were improved significantly using
the spring-damping feedback. This study presents a groundwork for adaptive
training in robotic surgery based on near-real-time human-centric models of
surgical behavior.",2101.00097v3
2021-01-08,Damped dust-ion-acoustic solitons in collisional magnetized nonthermal plasmas,"A multi-species magnetized collisional nonthermal plasma system containing
inertial ion species, non-inertial electron species following nonthermal
$\kappa-$ distribution, and immobile dust particles, is considered to examine
the characteristics of the dissipative dust-ion-acoustic (DIA) soliton modes,
\textbf{theoretically and parametrically}. The electrostatic solitary modes are
found to be associated with the low frequency dissipative dust-ion-acoustic
solitary waves (DIASWs). The ion-neutral collision is taken into account, and
the influence of ion-neutral collisional effects on the dynamics of dissipative
DIASWs is investigated. It is reported that most of the plasma mediums in space
and laboratory are far from thermal equilibrium, and the particles in such
plasma systems are well fitted via the $\kappa-$nonthermal distribution than
via the thermal Maxwellian distribution. The reductive perturbation approach is
adopted to derive the damped KdV (dKdV) equation, and the solitary wave
solution of the dKdV equation is derived via the tangent hyperbolic method to
analyze the basic features (amplitude, width, speed, time evolution, etc.) of
dissipative DIASWs. The propagation nature and also the basic features of
dissipative DIASWs are seen to influence significantly due to the variation of
the plasma configuration parameters and also due to the variation of the
supethermality index $\kappa$ in the considered plasma system. The implication
of the results of this study could be useful for better understanding the
electrostatic localized disturbances, in the ion length and time scale, in
space and experimental dusty plasmas, where the presence of excess energetic
electrons and ion-neutral collisional damping are accountable.",2101.03183v2
2020-12-28,Global complexity effects due to local damping in a nonlinear system in 1:3 internal resonance,"It is well-known that nonlinearity may lead to localization effects and
coupling of internally resonant modes. However, research focused primarily on
conservative systems commonly assumes that the near-resonant forced response
closely follows the autonomous dynamics. Our results for even a simple system
of two coupled oscillators with a cubic spring clearly contradict this common
belief. We demonstrate analytically and numerically global effects of a weak
local damping source in a harmonically forced nonlinear system under condition
of 1:3 internal resonance: The global motion becomes asynchronous, i.e., mode
complexity is introduced with a non-trivial phase difference between the modal
oscillations. In particular, we show that a maximum mode complexity with a
phase difference of $90^\circ$ is attained in a multi-harmonic sense. This
corresponds to a transition from generalized standing to traveling waves in the
system's modal space. We further demonstrate that the localization is crucially
affected by the system's damping. Finally, we propose an extension of the
definition of mode complexity and mode localization to nonlinear quasi-periodic
motions, and illustrate their application to a quasi-periodic regime in the
forced response.",2101.03233v1
2021-01-27,"New estimations of the added mass and damping of two cylinders vibrating in a viscous fluid, from theoretical and numerical approaches","This paper deals with the small oscillations of two circular cylinders
immersed in a viscous stagnant fluid. A new theoretical approach based on an
Helmholtz expansion and a bipolar coordinate system is presented to estimate
the fluid forces acting on the two bodies. We show that these forces are linear
combinations of the {\textcolor{black}{cylinder accelerations}} and velocities,
through viscous fluid added coefficients. {\textcolor{black}{To assess the
validity of this theory, we consider the case of two equal size cylinders, one
of them being stationary while the other one is forced sinusoidally}}. The
self-added mass and damping coefficients are shown to decrease with both the
Stokes number and the separation distance. The cross-added mass and damping
coefficients tend to increase with the Stokes number and the separation
distance. Compared to the inviscid results, the effect of viscosity is to add a
correction term which scales as $Sk^{-1/2}$. When the separation distance is
sufficiently large, the two cylinders behave as if they were independent and
the Stokes predictions for an isolated cylinder are recovered. Compared to
previous works, the present theory offers a simple and flexible alternative for
an easy determination of the fluid forces and related added coefficients. To
our knowledge, this is also the first time that a numerical approach based on a
penalization method is presented in the context of fluid-structure interactions
for relatively small Stokes numbers, and successfully compared to theoretical
predictions.",2101.11346v1
2021-01-28,Vortex-induced Vibrations of a Confined Circular Cylinder for Efficient Flow Power Extraction,"A simple method to increase the flow power extraction efficiency of a
circular cylinder, undergoing vortex-induced vibration (VIV), by confining it
between two parallel plates is proposed. A two-dimensional numerical study was
performed on VIV of a circular cylinder inside a parallel plate channel of
height H at Reynolds number 150 to quantify the improvement. The cylinder is
elastically mounted with a spring such that it is only free to vibrate in the
direction transverse to the channel flow and has a fixed mass ratio (m*) of 10.
The energy extraction process is modelled as a damper, with spatially constant
damping ration ((), attached to the cylinder. The simulations are performed by
varying the reduced velocity for a set of fixed mass-damping ({\alpha} = m*()
values ranging between 0 to 1. The blockage ratio (b = D/H) is varied from 0.25
to 0.5 by changing the channel height. The quasi-periodic initial branch found
for the unconfined cylinder shrinks with the increasing blockage. The extracted
power is found to increase rapidly with the blockage. For maximum blockage (b =
0.2), the maximum flow power extracted by the cylinder is an order of magnitude
larger as compared to what it would extract in an open domain with free stream
velocity equal to the channel mean velocity. The optimal mass-damping
({\alpha}c ) for extracting maximum power is found to lie between 0.2 to 0.3.
An expression is derived to predict the maximum extracted power from the
undamped response of a confined/unconfined cylinder. With the assumption
{\alpha}c = 0.25, the derived expression can predict the maximum power
extraction within +-20% of the actual values obtained from present and previous
numerical and experimental studies.",2101.11803v1
2012-05-14,Dynamics of multipartite quantum correlations under decoherence,"Quantum discord is an optimal resource for the quantification of classical
and non-classical correlations as compared to other related measures. Geometric
measure of quantum discord is another measure of quantum correlations.
Recently, the geometric quantum discord for multipartite states has been
introduced by Jianwei Xu [arxiv:quant/ph.1205.0330]. Motivated from the recent
study [Ann. Phys. 327 (2012) 851] for the bipartite systems, I have
investigated global quantum discord (QD) and geometric quantum discord (GQD)
under the influence of external environments for different multipartite states.
Werner-GHZ type three-qubit and six-qubit states are considered in inertial and
non-inertial settings. The dynamics of QD and GQD is investigated under
amplitude damping, phase damping, depolarizing and flipping channels. It is
seen that the quantum discord vanishes for p>0.75 in case of three-qubit GHZ
states and for p>0.5 for six qubit GHZ states. This implies that multipartite
states are more fragile to decoherence for higher values of N. Surprisingly, a
rapid sudden death of discord occurs in case of phase flip channel. However,
for bit flip channel, no sudden death happens for the six-qubit states. On the
other hand, depolarizing channel heavily influences the QD and GQD as compared
to the amplitude damping channel. It means that the depolarizing channel has
the most destructive influence on the discords for multipartite states. From
the perspective of accelerated observers, it is seen that effect of environment
on QD and GQD is much stronger than that of the acceleration of non-inertial
frames. The degradation of QD and GQD happens due to Unruh effect. Furthermore,
QD exhibits more robustness than GQD when the multipartite systems are exposed
to environment.",1205.3133v1
2017-04-29,Low-frequency wide band-gap elastic/acoustic meta-materials using the K-damping concept,"The terms ""acoustic/elastic meta-materials"" describe a class of periodic
structures with unit cells exhibiting local resonance. This localized resonant
structure has been shown to result in negative effective stiffness and/or mass
at frequency ranges close to these local resonances. As a result, these
structures present unusual wave propagation properties at wavelengths well
below the regime corresponding to band-gap generation based on spatial
periodicity, (i.e. ""Bragg scattering""). Therefore, acoustic/elastic
meta-materials can lead to applications, especially suitable in the
low-frequency range. However, low frequency range applications of such
meta-materials require very heavy internal moving masses, as well as additional
constraints at the amplitudes of the internally oscillating locally resonating
structures, which may prohibit their practical implementation. In order to
resolve this disadvantage, the K-Damping concept will be analyzed. According to
this concept, the acoustic/elastic meta-materials are designed to include
negative stiffness elements instead or in addition to the internally resonating
added masses. This concept removes the need for the heavy locally added heavy
masses, while it simultaneously exploits the negative stiffness damping
phenomenon. Application of both Bloch's theory and the classical modal analysis
at the one-dimensional mass-in-mass lattice is analyzed and corresponding
dispersion relations are derived. The results indicate significant advantages
over the conventional mass-in-a mass lattice, such as broader band-gaps and
increased damping ratio and reveal significant potential in the proposed
solution. Preliminary feasibility analysis for seismic meta-structures and low
frequency acoustic isolation-damping confirm the strong potential and
applicability of this concept.",1705.00226v2
2017-05-07,Precision cosmology with redshift-space bispectrum: a perturbation theory based model at one-loop order,"The large-scale matter distribution in the late-time Universe exhibits
gravity-induced non-Gaussianity, and the bispectrum, three-point cumulant is
expected to contain significant cosmological information. In particular, the
measurement of the bispectrum helps to tighten the constraints on dark energy
and modified gravity through the redshift-space distortions (RSD). In this
paper, extending the work by Taruya, Nishimichi & Saito (2010, Phys.Rev.D 82,
063522), we present a perturbation theory (PT) based model of redshift-space
matter bispectrum that can keep the non-perturbative damping effect under
control. Characterizing this non-perturbative damping by a univariate function
with single free parameter, the PT model of the redshift-space bispectrum is
tested against a large set of cosmological $N$-body simulations, finding that
the predicted monopole and quadrupole moments are in a good agreement with
simulations at the scales of baryon acoustic oscillations (well beyond the
range of agreement of standard PT). The validity of the univariate ansatz of
the damping effect is also examined, and with the PT calculation at
next-to-leading order, the fitted values of the free parameter is shown to
consistently match those obtained from the PT model of power spectrum by
Taruya, Nishimichi & Saito (2010).",1705.02574v1
2017-05-13,Large-amplitude longitudinal oscillations in a solar filament,"In this paper, we report our multiwavelength observations of the
large-amplitude longitudinal oscillations of a filament on 2015 May 3. Located
next to active region 12335, the sigmoidal filament was observed by the
ground-based H$\alpha$ telescopes from GONG and by AIA aboard SDO. The filament
oscillations were most probably triggered by the magnetic reconnection in the
filament channel. The directions of oscillations have angles of
4$^\circ$-36$^\circ$ with respect to the filament axis. The whole filament did
not oscillate in phase as a rigid body. Meanwhile, the periods (3100$-$4400 s)
of oscillations have a spatial dependence. The values of $R$ are estimated to
be 69.4$-$133.9 Mm, and the minimum transverse magnetic field of the dips is
estimated to be 15 G. The amplitudes of S5-S8 grew with time, while the
amplitudes of S9-S14 damped with time. The amplitudes of oscillations range
from a few to ten Mm, and the maximal velocity can reach 30 km s$^{-1}$.
Interestingly, the filament experienced mass drainage southwards at a speed of
$\sim$27 km s$^{-1}$. The oscillations continued after the mass drainage and
lasted for more than 11 hr. After the mass drainage, the phases of oscillations
did not change a lot. The periods of S5-S8 decreased, while the periods of
S9-S14 increased. The amplitudes of S5$-$S8 damped with time, while the
amplitudes of S9-S14 grew. Most of the damping (growing) ratios are between -9
and 14. We propose a schematic cartoon to explain the complex behaviors of
oscillations by introducing thread-thread interaction.",1705.04820v1
2017-05-14,Inter-Area Oscillation Damping With Non-Synchronized Wide-Area Power System Stabilizer,"One of the major issues in an interconnected power system is the low damping
of inter-area oscillations which significantly reduces the power transfer
capability. Advances in Wide-Area Measurement System (WAMS) makes it possible
to use the information from geographical distant location to improve power
system dynamics and performances. A speed deviation based Wide-Area Power
System Stabilizer (WAPSS) is known to be effective in damping inter-area modes.
However, the involvement of wide-area signals gives rise to the problem of
time-delay, which may degrade the system performance. In general, time-stamped
synchronized signals from Phasor Data Concentrator (PDC) are used for WAPSS, in
which delays are introduced in both local and remote signals. One can opt for a
feedback of remote signal only from PDC and uses the local signal as it is
available, without time synchronization. This paper utilizes configurations of
time-matched synchronized and nonsychronized feedback and provides the
guidelines to design the controller. The controllers are synthesized using
$H_\infty$ control with regional pole placement for ensuring adequate dynamic
performance. To show the effectiveness of the proposed approach, two power
system models have been used for the simulations. It is shown that the
controllers designed based on the nonsynchronized signals are more robust to
time time delay variations than the controllers using synchronized signal.",1705.04953v2
2017-05-19,Analytical Prediction of Reflection Coefficients for Wave Absorbing Layers in Flow Simulations of Regular Free-Surface Waves,"Undesired wave reflections, which occur at domain boundaries in flow
simulations with free-surface waves, can be minimized by applying source terms
in the vicinity of the boundary to damp the waves. Examples of such approaches
are absorbing layers, damping zones, forcing zones, relaxation zones and sponge
layers. A problem with these approaches is that the effectivity of the wave
damping depends on the parameters in the source term functions, which are
case-dependent and must be adjusted to the wave. The present paper presents a
theory which analytically predicts the reflection coefficients and which can be
used to optimally select the source term parameters before running the
simulation. The theory is given in a general form so that it is applicable to
many existing implementations. It is validated against results from
finite-volume-based flow simulations of regular free-surface waves and found to
be of satisfactory accuracy for practical purposes.",1705.06940v2
2017-09-21,Low Gilbert Damping Constant in Perpendicularly Magnetized W/CoFeB/MgO Films with High Thermal Stability,"Perpendicular magnetic materials with low damping constant and high thermal
stability have great potential for realizing high-density, non-volatile, and
low-power consumption spintronic devices, which can sustain operation
reliability for high processing temperatures. In this work, we study the
Gilbert damping constant ({\alpha}) of perpendicularly magnetized W/CoFeB/MgO
films with a high perpendicular magnetic anisotropy (PMA) and superb thermal
stability. The {\alpha} of these PMA films annealed at different temperatures
is determined via an all-optical Time-Resolved Magneto-Optical Kerr Effect
method. We find that {\alpha} of these W/CoFeB/MgO PMA films decreases with
increasing annealing temperature, reaches a minimum of {\alpha} = 0.016 at an
annealing temperature of 350 {\deg}C, and then increases to 0.024 after
post-annealing at 400 {\deg}C. The minimum {\alpha} observed at 350 {\deg}C is
rationalized by two competing effects as the annealing temperature becomes
higher: the enhanced crystallization of CoFeB and dead-layer growth occurring
at the two interfaces of the CoFeB layer. We further demonstrate that {\alpha}
of the 400 {\deg}C-annealed W/CoFeB/MgO film is comparable to that of a
reference Ta/CoFeB/MgO PMA film annealed at 300 {\deg}C, justifying the
enhanced thermal stability of the W-seeded CoFeB films.",1709.07483v1
2017-11-10,"Vortex axisymmetrization, inviscid damping, and vorticity depletion in the linearized 2D Euler equations","Coherent vortices are often observed to persist for long times in turbulent
2D flows even at very high Reynolds numbers and are observed in experiments and
computer simulations to potentially be asymptotically stable in a weak sense
for the 2D Euler equations. We consider the incompressible 2D Euler equations
linearized around a radially symmetric, strictly monotone decreasing vorticity
distribution. For sufficiently regular data, we prove the inviscid damping of
the $\theta$-dependent radial and angular velocity fields with the optimal
rates $\|u^r(t)\| \lesssim \langle t \rangle^{-1}$ and $\|u^\theta(t)\|
\lesssim \langle t \rangle^{-2}$ in the appropriate radially weighted $L^2$
spaces. We moreover prove that the vorticity weakly converges back to radial
symmetry as $t \rightarrow \infty$, a phenomenon known as vortex
axisymmetrization in the physics literature, and characterize the dynamics in
higher Sobolev spaces. Furthermore, we prove that the $\theta$-dependent
angular Fourier modes in the vorticity are ejected from the origin as $t \to
\infty$, resulting in faster inviscid damping rates than those possible with
passive scalar evolution. This non-local effect is called vorticity depletion.
Our work appears to be the first to find vorticity depletion relevant for the
dynamics of vortices.",1711.03668v1
2017-11-15,Anomalous spin-orbit torque switching due to field-like torque-assisted domain wall reflection,"Spin-orbit torques (SOT) allow the electrical control of magnetic states.
Current-induced SOT switching of the perpendicular magnetization is of
particular technological importance. The SOT consists of damping-like and
field-like torques so that the efficient SOT switching requires to understand
combined effects of the two torque-components. Previous quasi-static
measurements have reported an increased switching probability with the width of
current pulses, as predicted with considering the damping-like torque only.
Here we report a decreased switching probability at longer pulse-widths, based
on time-resolved measurements. Micromagnetic analysis reveals that this
anomalous SOT switching results from domain wall reflections at sample edges.
The domain wall reflection is found to strongly depend on the field-like torque
and its relative sign to the damping-like torque. Our result demonstrates a key
role of the field-like torque in the deterministic SOT switching and notifies
the importance of sign correlation of the two torque-components, which may shed
light on the SOT switching mechanism.",1711.05367v1
2017-11-24,Influence of surfactants on the electrohydrodynamic stretching of water drops in oil,"In this paper we present experimental and numerical studies of the
electrohydrodynamic stretching of a sub-millimetre-sized salt water drop,
immersed in oil with added non-ionic surfactant, and subjected to a suddenly
applied electric field of magnitude approaching 1 kV/mm. By varying the drop
size, electric field strength and surfactant concentration we cover the whole
range of electric capillary numbers ($Ca_E$) from 0 up to the limit of drop
disintegration. The results are compared with the analytical result by Taylor
(1964) which predicts the asymptotic deformation as a function of $Ca_E$. We
find that the addition of surfactant damps the transient oscillations and that
the drops may be stretched slightly beyond the stability limit found by Taylor.
We proceed to study the damping of the oscillations, and show that increasing
the surfactant concentration has a dual effect of first increasing the damping
at low concentrations, and then increasing the asymptotic deformation at higher
concentrations. We explain this by comparing the Marangoni forces and the
interfacial tension as the drops deform. Finally, we have observed in the
experiments a significant hysteresis effect when drops in oil with large
concentration of surfactant are subjected to repeated deformations with
increasing electric field strengths. This effect is not attributable to the
flow nor the interfacial surfactant transport.",1711.08969v2
2017-11-30,Model-independent analysis of the DAMPE excess,"The Dark Matter Particle Explorer (DAMPE) recently released measurements of
the electron spectrum with a hint of a narrow peak at about 1.4 TeV. We
investigate dark matter (DM) models that could produce such a signal by
annihilation in a nearby subhalo whilst simultaneously satisfying constraints
from DM searches. In our model-independent approach, we consider all
renormalizable interactions via a spin 0 or 1 mediator between spin 0 or 1/2 DM
particles and the Standard Model leptons. We find that of the 20 combinations,
10 are ruled out by velocity or helicity suppression of the annihilation cross
section to fermions. The remaining 10 models, though, evade constraints from
the relic density, collider and direct detection searches, and include models
of spin 0 and 1/2 DM coupling to a spin 0 or 1 mediator. We delineate the
regions of mediator mass and couplings that could explain the DAMPE excess. In
all cases the mediator is required to be heaver than about 2 TeV by LEP limits.",1711.11376v3
2018-03-22,Propagative and diffusive regimes of acoustic damping in bulk amorphous material,"In amorphous solids, a non-negligible part of thermal conductivity results
from phonon scattering on the structural disorder. The conversion of acoustic
energy into thermal energy is often measured by the Dynamical Structure Factor
(DSF) thanks to inelastic neutron or X-Ray scattering. The DSF is used to
quantify the dispersion relation of phonons, together with their damping.
However, the connection of the dynamical structure factor with dynamical
attenuation of wave packets in glasses is still a matter of debate. We focus
here on the analysis of wave packets propagation in numerical models of
amorphous silicon. We show that the DHO fits (Damped Harmonic Oscillator model)
of the dynamical structure factors give a good estimate of the wave packets
mean-free path, only below the Ioffe-Regel limit. Above the Ioffe-Regel limit
and below the mobility edge, a pure diffusive regime without a definite mean
free path is observed. The high-frequency mobility edge is characteristic of a
transition to localized vibrations. Below the Ioffe-Regel criterion, a mixed
regime is evidenced at intermediate frequencies, with a coexistence of
propagative and diffusive wave fronts. The transition between these different
regimes is analyzed in details and reveals a complex dynamics for energy
transportation, thus raising the question of the correct modeling of thermal
transport in amorphous materials.",1803.08594v1
2018-06-04,Density Waves and the Viscous Overstability in Saturn's Rings,"This paper addresses resonantly forced spiral density waves in a dense
planetary ring which is close to the threshold for viscous overstability. We
solve numerically the hydrodynamical equations for a dense, axisymmetric thin
disk in the vicinity of an inner Lindblad resonance with a perturbing
satellite. The spiral shape of a density wave is taken into account through a
suitable approximation of the advective terms arising from the fluid orbital
motion. This paper is a first attempt to model the co-existence of resonantly
forced density waves and short-scale axisymmetric overstable wavetrains in
Saturn's rings by conducting large-scale hydrodynamical integrations. These
integrations reveal that the two wave types undergo complex interactions, not
taken into account in existing models for the damping of density waves. In
particular it is found that, depending on the relative magnitude of both wave
types, the presence of viscous overstability can lead to a damping of an
unstable density wave and vice versa. The damping of viscous overstability by a
density wave is investigated further by employing a simplified model of an
axisymmetric ring perturbed by a nearby Lindblad resonance. A linear
hydrodynamic stability analysis as well as local N-body simulations of this
model system are performed and support the results of our large-scale
hydrodynamical integrations.",1806.01211v3
2018-07-26,Aspherical deformations of the Choptuik spacetime,"We perform dynamical and nonlinear numerical simulations to study critical
phenomena in the gravitational collapse of massless scalar fields in the
absence of spherical symmetry. We evolve axisymmetric sets of initial data and
examine the effects of deviation from spherical symmetry. For small deviations
we find values for the critical exponent and echoing period of the discretely
self-similar critical solution that agree well with established values;
moreover we find that such small deformations behave like damped oscillations
whose damping coefficient and oscillation frequencies are consistent with those
predicted in the linear perturbation calculations of Martin-Garcia and
Gundlach. However, we also find that the critical exponent and echoing period
appear to decrease with increasing departure from sphericity, and that, for
sufficiently large departures from spherical symmetry, the deviations become
unstable and grow, confirming earlier results by Choptuik et.al.. We find some
evidence that these growing modes lead to a bifurcation, similar to those
reported by Choptuik et.al., with two centers of collapse forming on the
symmetry axis above and below the origin. These findings suggest that nonlinear
perturbations of the critical solution lead to changes in the effective values
of the critical exponent, echoing period and damping coefficient, and may even
change the sign of the latter, so that perturbations that are stable in the
linear regime can become unstable in the nonlinear regime.",1807.10342v2
2018-08-03,Witnessing galaxy assembly at the edge of the reionization epoch,"We report the discovery of Serenity-18, a galaxy at z=5.939 for which we
could measure the content of molecular gas, M(H_2)~ 5 x10^9 M_sun, traced by
the CO(6-5) emission, together with the metal-poor ([Fe/H]=-3.08 +- 0.12,
[Si/H]=-2.86 +- 0.14) gas clump/filament which is possibly feeding its growth.
The galaxy has an estimated star formation rate of ~100 M_sun yr^{-1}, implying
that it is a typical main sequence galaxy at these redshifts. The metal-poor
gas is detected through a damped Lyman-alpha absorber (DLA) observed at a
spatial separation of 40 kpc and at the same redshift of Serenity-18, along the
line of sight to the quasar SDSS J2310+1855 (z_em = 6.0025). The chemical
abundances measured for the damped Lyman-alpha system are in very good
agreement with those measured for other DLAs discovered at similar redshifts,
indicating an enrichment due to massive PopII stars. The galaxy/Damped system
we discovered is a direct observational evidence of the assembly of a galaxy at
the edge of the reionization epoch.",1808.01146v2
2018-08-13,Fluidization of collisionless plasma turbulence,"In a collisionless, magnetized plasma, particles may stream freely along
magnetic-field lines, leading to phase ""mixing"" of their distribution function
and consequently to smoothing out of any ""compressive"" fluctuations (of
density, pressure, etc.,). This rapid mixing underlies Landau damping of these
fluctuations in a quiescent plasma-one of the most fundamental physical
phenomena that make plasma different from a conventional fluid. Nevertheless,
broad power-law spectra of compressive fluctuations are observed in turbulent
astrophysical plasmas (most vividly, in the solar wind) under conditions
conducive to strong Landau damping. Elsewhere in nature, such spectra are
normally associated with fluid turbulence, where energy cannot be dissipated in
the inertial scale range and is therefore cascaded from large scales to small.
By direct numerical simulations and theoretical arguments, it is shown here
that turbulence of compressive fluctuations in collisionless plasmas strongly
resembles one in a collisional fluid and does have broad power-law spectra.
This ""fluidization"" of collisionless plasmas occurs because phase mixing is
strongly suppressed on average by ""stochastic echoes"", arising due to nonlinear
advection of the particle distribution by turbulent motions. Besides resolving
the long-standing puzzle of observed compressive fluctuations in the solar
wind, our results suggest a conceptual shift for understanding kinetic plasma
turbulence generally: rather than being a system where Landau damping plays the
role of dissipation, a collisionless plasma is effectively dissipationless
except at very small scales. The universality of ""fluid"" turbulence physics is
thus reaffirmed even for a kinetic, collisionless system.",1808.04284v1
2018-08-15,Neural Material: Learning Elastic Constitutive Material and Damping Models from Sparse Data,"The accuracy and fidelity of deformation simulations are highly dependent
upon the underlying constitutive material model. Commonly used linear or
nonlinear constitutive material models only cover a tiny part of possible
material behavior. In this work we propose a unified framework for modeling
deformable material. The key idea is to use a neural network to correct a
nominal model of the elastic and damping properties of the object. The neural
network encapsulates a complex function that is hard to explicitly model. It
injects force corrections that help the forward simulation to more accurately
predict the true behavior of a given soft object, which includes non-linear
elastic forces and damping. Attempting to satisfy the requirement from real
material interference and animation design scenarios, we learn material models
from examples of dynamic behavior of a deformable object's surface. The
challenge is that such data is sparse as it is consistently given only on part
of the surface. Sparse reduced space-time optimization is employed to gradually
generate increasingly accurate training data, which further refines and
enhances the neural network. We evaluate our choice of network architecture and
show evidence that the modest amount of training data we use is suitable for
the problem tackled. Our method is demonstrated with a set of synthetic
examples.",1808.04931v1
2018-12-07,Magnetic Braking and Damping of Differential Rotation in Massive Stars,"Fragmentation of highly differentially rotating massive stars that undergo
collapse has been suggested as a possible channel for binary black hole
formation. Such a scenario could explain the formation of the new population of
massive black holes detected by the LIGO/VIRGO gravitational wave laser
interferometers. We probe that scenario by performing general relativistic
magnetohydrodynamic simulations of differentially rotating massive stars
supported by thermal radiation pressure plus a gas pressure perturbation. The
stars are initially threaded by a dynamically weak, poloidal magnetic field
confined to the stellar interior. We find that magnetic braking and turbulent
viscous damping via magnetic winding and the magnetorotational instability in
the bulk of the star redistribute angular momentum, damp differential rotation
and induce the formation of a massive and nearly uniformly rotating inner core
surrounded by a Keplerian envelope. The core + disk configuration evolves on a
secular timescale and remains in quasi-stationary equilibrium until the
termination of our simulations. Our results suggest that the high degree of
differential rotation required for $m=2$ seed density perturbations to trigger
gas fragmentation and binary black hole formation is likely to be suppressed
during the normal lifetime of the star prior to evolving to the point of
dynamical instability to collapse. Other cataclysmic events, such as stellar
mergers leading to collapse, may therefore be necessary to reestablish
sufficient differential rotation and density perturbations to drive
nonaxisymmetric modes leading to binary black hole formation.",1812.03176v3
2018-12-18,Inferring physical parameters in solar prominence threads,"High resolution observations have permitted to resolve the solar
prominences/filaments as sets of threads/fibrils. However, the values of the
physical parameters of these threads and their structuring remain poorly
constrained. We use prominence seismology techniques to analyse transverse
oscillations in threads through the comparison between magnetohydrodynamic
(MHD) models and observations. We apply Bayesian methods to obtain two
different types of information. We first infer the marginal posterior
distribution of physical parameters, such as the magnetic field strength or the
length of the thread, when a totally filled tube, a partially filled tube, and
three damping models (resonant absorption in the Alfv\'en continuum, resonant
absorption in the slow continuum, and Cowling's diffusion) are considered as
certain. Then, we compare the relative plausibility between alternative MHD
models by computing the Bayes factors. Well constrained probability density
distributions can be obtained for the magnetic field strength, the length of
the thread, the density contrast, and parameters associated to damping models.
When comparing the damping models of resonant absorption in the Alfv\'en
continuum, resonant absorption in the slow continuum and Cowling's diffusion
due to partial ionisation of prominence plasma, the resonant absorption in the
Alfv\'en continuum is the most plausible mechanism in explaining the existing
observations. Relations between periods of fundamental and first overtone kink
modes with values around 1 are better explained by expressions of the period
ratio in the long thread approximation, while the rest of the values are more
probable in the short thread limit for the period ratio. Our results show that
Bayesian analysis offers valuable methods for performing parameter inference
and model comparison in the context of prominence seismology.",1812.07262v1
2019-01-07,Abnormal anti-crossing effect in photon-magnon coupling,"We report the experimental demonstration of an abnormal, opposite
anti-crossing effect in a photon-magnon-coupled system that consists of an
Yttrium Iron Garnet film and an inverted pattern of split-ring resonator
structure (noted as ISRR) in a planar geometry. It is found that the normal
shape of anti-crossing dispersion typically observed in photon-magnon coupling
is changed to its opposite anti-crossing shape just by changing the
position/orientation of the ISRR's split gap with respect to the microstrip
line axis along which ac microwave currents are applied. Characteristic
features of the opposite anti-crossing dispersion and its linewidth evolution
are analyzed with the help of analytical derivations based on electromagnetic
interactions. The observed opposite anti-crossing dispersion is ascribed to the
compensation of both intrinsic damping and coupling-induced damping in the
magnon modes. This compensation is achievable by controlling the relative
strength and phase of oscillating magnetic fields generated from the ISRR's
split gap and the microstrip feeding line. The position/orientation of an
ISRR's split gap provides a robust means of controlling the dispersion shape of
anti-crossing and its damping in a photon-magnon coupling, thereby offering
more opportunity for advanced designs of microwave devices.",1901.01729v2
2019-01-24,A compact actively damped vibration isolation platform for optical experiments in ultra-high vacuum,"We present a tabletop six-axis vibration isolation system, compatible with
Ultra-High Vacuum (UHV), which is actively damped and provides 25 dB of
isolation at 10 Hz and 65 dB at 100 Hz. While this isolation platform has been
primarily designed to support optics in the Laser Interferometer
Gravitational-Wave Observatory (LIGO) detectors, it is suitable for a variety
of applications. The system has been engineered to facilitate the construction
and assembly process, while minimizing cost. The platform provides passive
isolation for six degrees of freedom using a combination of vertical springs
and horizontal pendula. It is instrumented with voice-coil actuators and
optical shadow sensors to damp the resonances. All materials are compatible
with stringent vacuum requirements. Thanks to its architecture, the system's
footprint can be adapted to meet spatial requirements, while maximizing the
dimensions of the optical table. Three units are currently operating for LIGO.
We present the design of the system, controls principle, and experimental
results.",1901.09666v2
2019-01-28,Strong damping-like spin-orbit torque and tunable Dzyaloshinskii-Moriya interaction generated by low-resistivity Pd$_{1-x}$Pt$_x$ alloys,"Despite their great promise for providing a pathway for very efficient and
fast manipulation of magnetization at the nanoscale, spin-orbit torque (SOT)
operations are currently energy inefficient due to a low damping-like SOT
efficiency per unit current bias, and/or the very high resistivity of the spin
Hall materials. Here, we report an advantageous spin Hall material, Pd1-xPtx,
which combines a low resistivity with a giant spin Hall effect as evidenced
through the use of three independent SOT ferromagnetic detectors. The optimal
Pd0.25Pt0.75 alloy has a giant internal spin Hall ratio of >0.47 (damping-like
SOT efficiency of ~ 0.26 for all three ferromagnets) and a low resistivity of
~57.5 {\mu}{\Omega} cm at 4 nm thickness. Moreover, we find the
Dzyaloshinskii-Moriya interaction (DMI), the key ingredient for the
manipulation of chiral spin arrangements (e.g. magnetic skyrmions and chiral
domain walls), is considerably strong at the Pd1-xPtx/Fe0.6Co0.2B0.2 interface
when compared to that at Ta/Fe0.6Co0.2B0.2 or W/Fe0.6Co0.2B0.2 interfaces and
can be tuned by a factor of 5 through control of the interfacial spin-orbital
coupling via the heavy metal composition. This work establishes a very
effective spin current generator that combines a notably high energy efficiency
with a very strong and tunable DMI for advanced chiral spintronics and spin
torque applications.",1901.09954v1
2019-02-13,Two-mediator dark matter models and cosmic electron excess,"The cosmic electron energy spectrum recently observed by the DAMPE experiment
exhibits two interesting features, including a break around 0.9 TeV and a sharp
resonance near 1.4 TeV. In this analysis, we propose a dark matter explanation
to both exotic features seen by DAMPE. In our model, dark matter annihilates in
the galaxy via two different channels that lead to both a narrow resonance
spectrum near 1.4 TeV and electron excess events over an extended energy range
thus generating the break structure around TeV. The two annihilation channels
are mediated by two gauge bosons that interact both with dark matter and with
the standard model fermions. Dark matter annihilations through the s-channel
process mediated by the heavier boson produce monoenergetic electron-positron
pairs leading to the resonance excess. The lighter boson has a mass smaller
than the dark matter such that they can be on-shell produced in dark matter
annihilations in the galaxy; the lighter bosons in the final state subsequently
decay to generate the extended excess events due to the smeared electron energy
spectrum in this process. We further analyze constraints from various
experiments, including HESS, Fermi, AMS, and LHC, to the parameter space of the
model where both excess events can be accounted for. In order to interpret the
two new features in the DAMPE data, dark matter annihilation cross sections in
the current galaxy are typically much larger than the canonical thermal cross
section needed for the correct dark matter relic abundance. This discrepancy,
however, is remedied by the nonperturbative Sommerfeld enhancement because of
the existence of a lighter mediator in the model.",1902.04916v1
2019-02-18,Coherent control of magnon radiative damping with local photon states,"The collective excitation of ordered spins, known as spin waves or magnons,
can in principle radiate by emitting travelling photons to an open system when
decaying to the ground state. However, in contrast to the electric dipoles,
magnetic dipoles contributed by magnons are more isolated from electromagnetic
environment with negligible radiation in the vacuum, limiting their application
in coherent communication by photons. Recently, strong interaction between
cavity standing-wave photons and magnons has been reported, indicating the
possible manipulation of magnon radiation via tailoring photon states. Here,
with loading an yttrium iron garnet sphere in a one-dimensional circular
waveguide cavity in the presence of both travelling and standing photon modes,
we demonstrate an efficient photon emissions from magnon and a significant
magnon radiative damping with radiation rate found to be proportional to the
local density of states (LDOS) of photon. By modulating the LDOS including its
magnitude and/or polarization, we can flexibly tune the photon emission and
magnon radiative damping on demand. Our findings provide a general way in
manipulating photon emission from magnon radiation for harnessing energy and
angular momentum generation, transfer and storage modulated by magnon in the
cavity and waveguide electrodynamics.",1902.06795v2
2019-03-04,Quantum speed limit time for the damped Jaynes-Cummings and Ohmic-like dephasing models in Schwarzschild spacetime,"Quantum theory sets the bound on the minimal evolution time between initial
and final states of the quantum system. This minimal evolution time can be used
to specify the maximal speed of the evolution in open and closed quantum
systems. Quantum speed limit is one of the interesting issue in the theory of
open quantum systems. One may investigate the influence of the relativistic
effect on the quantum speed limit time. When several observers are placed in
different inertial or non-inertial frames, or in Schwarzschild space-time, the
relativistic effect should be taken into account. In this work, the quantum
speed limit time in Schwarzschild space-time will be studied for two various
model consist of damped Jaynes-Cummings and Ohmic-like dephasing. First, it
will be observed that how quantum coherence is affected by Hawking radiation.
According to the dependence of quantum speed limit time on quantum coherence
and the dependence of quantum coherence on relative distance of quantum system
to event horizon $R_{0}$, it will be represented that the quantum speed limit
time in Schwarzschild space-time is decreased by increasing $R_{0}$ for damped
Jaynes-Cummings model and conversely, It is increased by increasing $R_{0}$ for
Ohmic-like dephasing model .",1903.01230v2
2019-03-07,Non-linear diffusion of cosmic rays escaping from supernova remnants - II. Hot ionized media,"We study the problem of the escape and transport of Cosmic-Rays (CR) from a
source embedded in a fully ionised, hot phase of the interstellar medium (HIM).
In particular, we model the CR escape and their propagation in the source
vicinity taking into account excitation of Alfv\'enic turbulence by CR
streaming and mechanisms damping the self-excited turbulence itself. Our
estimates of escape radii and times result in large values (100 pc,
$2\times10^5$ yr) for particle energies $\lesssim20$ GeV and smaller values for
particles with increasing energies (35 pc and 14 kyr at 1 TeV). These escape
times and radii, when used as initial conditions for the CR propagation outside
the source, result in relevant suppression of the diffusion coefficient (by a
factor 5-10) on time-scales comparable with their (energy dependent) escape
time-scale. The damping mechanisms are fast enough that even on shorter time
scales the Alfv\'enic turbulence is efficiently damped, and the ratio between
random and ordered component of the magnetic field is $\delta B/B_0\ll 1$,
justifying the use of quasi-linear theory. In spite of the suppressed diffusion
coefficient, and then the increased residence time in the vicinity (<200 pc) of
their source, the grammage accumulated by CRs after their escape is found to be
negligible (at all energies) as compared to the one accumulated while diffusing
in the whole Galaxy, due to the low density of the HIM.",1903.03193v1
2019-03-25,Stabilised Asynchronous Fast Adaptive Composite Multigrid using Additive Damping,"Multigrid solvers face multiple challenges on parallel computers. Two
fundamental ones read as follows: Multiplicative solvers issue coarse grid
solves which exhibit low concurrency and many multigrid implementations suffer
from an expensive coarse grid identification phase plus adaptive mesh
refinement overhead. We propose a new additive multigrid variant for
spacetrees, i.e. meshes as they are constructed from octrees and quadtrees: It
is an additive scheme, i.e. all multigrid resolution levels are updated
concurrently. This ensures a high concurrency level, while the transfer
operators between the mesh levels can still be constructed algebraically. The
novel flavour of the additive scheme is an augmentation of the solver with an
additive, auxiliary damping parameter per grid level per vertex that is in turn
constructed through the next coarser level---an idea which utilises smoothed
aggregation principles or the motivation behind AFACx: Per level, we solve an
additional equation whose purpose is to damp too aggressive solution updates
per vertex which would otherwise, in combination with all the other levels,
yield an overcorrection and, eventually, oscillations. This additional equation
is constructed additively as well, i.e. is once more solved concurrently to all
other equations. This yields improved stability, closer to what is seen with
multiplicative schemes, while pipelining techniques help us to write down the
additive solver with single-touch semantics for dynamically adaptive meshes.",1903.10367v3
2019-04-04,The DAMPE excess and gamma-ray constraints,"The direct measurements of the cosmic electron-positron spectrum around 1 TeV
made by DAMPE have induced many theoretical speculations about possible
excesses in the data above the standard astrophysical predictions that might
have the dark matter (DM) origin. These attempts mainly fall into two
categories: i) DM annihilation (or decay) in the Galactic halo producing the
broad spectrum excess; ii) DM annihilation in the nearby compact subhalo
producing the sharp peak at 1.4 TeV. We investigate the gamma-ray emission
accompanying $e^+e^-$ production in DM annihilation, as well as various
theoretical means to suppress the prompt radiation, such as specific
interaction vertices or multi-cascade modes, and conclude that these attempts
are in tension with various gamma-ray observations. We show that the DM
explanations of the broad spectrum excess tend to contradict the diffuse
isotropic gamma-ray background (IGRB), measured by Fermi-LAT, while the nearby
subhalo scenario is constrained by nonobservation in the surveys, performed by
Fermi-LAT, MAGIC and HESS. We also briefly review other types of gamma-ray
constraints, which seem to rule out the DM interpretations of the DAMPE broad
spectrum excess as well.",1904.02456v2
2019-04-10,Stochastic nonlinear wave dynamics on compact surfaces,"We study the Cauchy problem for the nonlinear wave equations (NLW) with
random data and/or stochastic forcing on a two-dimensional compact Riemannian
manifold without boundary. (i) We first study the defocusing stochastic damped
NLW driven by additive space-time white-noise, and with initial data
distributed according to the Gibbs measure. By introducing a suitable
space-dependent renormalization, we prove local well-posedness of the
renormalized equation. Bourgain's invariant measure argument then allows us to
establish almost sure global well-posedness and invariance of the Gibbs measure
for the renormalized stochastic damped NLW. (ii) Similarly, we study the random
data defocusing NLW (without stochastic forcing), and establish the same
results as in the previous setting. (iii) Lastly, we study the stochastic NLW
without damping. By introducing a space-time dependent renormalization, we
prove its local well-posedness with deterministic initial data in all
subcritical spaces.
  These results extend the corresponding recent results on the two-dimensional
torus obtained by (i) Gubinelli-Koch-Oh-Tolomeo (2018), (ii) Oh-Thomann (2017),
and (iii) Gubinelli-Koch-Oh (2018), to a general class of compact manifolds.
The main ingredient is the Green's function estimate for the Laplace-Beltrami
operator in this setting to study regularity properties of stochastic terms
appearing in each of the problems.",1904.05277v3
2019-04-30,Damping rates and frequency corrections of Kepler LEGACY stars,"Linear damping rates and modal frequency corrections of radial oscillation
modes in selected LEGACY main-sequence stars are estimated by means of a
nonadiabatic stability analysis. The selected stellar sample covers stars
observed by Kepler with a large range of surface temperatures and surface
gravities. A nonlocal, time-dependent convection model is perturbed to assess
stability against pulsation modes. The mixing-length parameter is calibrated to
the surface-convection-zone depth of a stellar model obtained from fitting
adiabatic frequencies to the LEGACY observations, and two of the nonlocal
convection parameters are calibrated to the corresponding LEGACY linewidth
measurements. The remaining nonlocal convection parameters in the 1D
calculations are calibrated so as to reproduce profiles of turbulent pressure
and of the anisotropy of the turbulent velocity field of corresponding 3D
hydrodynamical simulations. The atmospheric structure in the 1D stability
analysis adopts a temperature-optical-depth relation derived from 3D
hydrodynamical simulations. Despite the small number of parameters to adjust,
we find good agreement with detailed shapes of both turbulent pressure profiles
and anisotropy profiles with depth, and with damping rates as a function of
frequency. Furthermore, we find the absolute modal frequency corrections,
relative to a standard adiabatic pulsation calculation, to increase with
surface temperature and surface gravity.",1904.13170v1
2019-08-08,Anisotropic damping of the spin fluctuations in doped La2-xSrxCuO4 studied by resonant inelastic x-ray scattering,"We report high-resolution resonant inelastic x-ray scattering (RIXS)
measurements of the collective spin fluctuations in three compositions of the
superconducting cuprate system La2-xSrxCuO4. We have mapped out the excitations
throughout much of the 2-D (h,k) Brillouin zone. The spin fluctuations in
La2-xSrxCuO4 are found to be fairly well-described by a damped harmonic
oscillator model, thus our data allows us to determine the full wavevector
dependence of the damping parameter. This parameter increases with doping and
is largest along the (h, h) line, where it is peaked near (0.2,0.2). We have
used a new procedure to determine the absolute wavevector-dependent
susceptibility for the doped compositions La2-xSrxCuO4 (x=0.12,0.16) by
normalising our data to La2CuO4 measurements made with inelastic neutron
scattering (INS). We find that the evolution with doping of the intensity of
high-energy excitations measured by RIXS and INS is consistent. For the doped
compositions, the wavevector-dependent susceptibility is much larger at
(1/4,1/4) than at (1/2,0). It increases rapidly along the (h,h) line towards
the antiferromagnetic wavevector of the parent compound (1/2,1/2). Thus, the
strongest magnetic excitations, and those predicted to favour superconductive
pairing, occur towards the (1/2,1/2) position as observed by INS.",1908.03086v2
2019-08-14,Two-fluid simulations of waves in the solar chromosphere II. Propagation and damping of fast magneto-acoustic waves and shocks,"Waves and shocks traveling through the solar chromospheric plasma are
influenced by its partial ionization and weak collisional coupling, and may
become susceptible to multi-fluid effects, similar to interstellar shock waves.
In this study, we consider fast magneto-acoustic shock wave formation and
propagation in a stratified medium, that is permeated by a horizontal magnetic
field, with properties similar to that of the solar chromosphere. The evolution
of plasma and neutrals is modeled using a two-fluid code that evolves a set of
coupled equations for two separate fluids. We observed that waves in neutrals
and plasma, initially coupled at the upper photosphere, become uncoupled at
higher heights in the chromosphere. This decoupling can be a consequence of
either the characteristic spatial scale at the shock front, that becomes
similar to the collisional scale, or the change in the relation between the
wave frequency, ion cyclotron frequency, and the collisional frequency with
height. The decoupling height is a sensitive function of the wave frequency,
wave amplitude, and the magnetic field strength. We observed that decoupling
causes damping of waves and an increase in the background temperature due to
the frictional heating. The comparison between analytical and numerical results
allows us to separate the role of the nonlinear effects from the linear ones on
the decoupling and damping of waves.",1908.05262v1
2019-11-01,Importance of Giant Impact Ejecta for Orbits of Planets Formed during the Giant Impact Era,"Terrestrial planets are believed to be formed via giant impacts of Mars-sized
protoplanets. Planets formed via giant impacts have highly eccentric orbits. A
swarm of planetesimals around the planets may lead to eccentricity damping for
the planets via the equipartition of random energies (dynamical friction).
However, dynamical friction increases eccentricities of planetesimals,
resulting in high velocity collisions between planetesimals. The collisional
cascade grinds planetesimals to dust until dust grains are blown out due to
radiation pressure. Therefore, the total mass of planetesimals decreases due to
collisional fragmentation, which weakens dynamical friction. We investigate the
orbital evolution of protoplanets in a planetesimal disk, taking into account
collisional fragmentation of planetesimals. For 100 km-sized or smaller
planetesimals, dynamical friction is insignificant for eccentricity damping of
planets because of collisional fragmentation. On the other hand, giant impacts
eject collisional fragments. Although the total mass of giant impact ejecta is
0.1-0.3 Earth masses, the largest impact ejecta are ~ 1,000 km in size. We also
investigate the orbital evolution of single planets with initial eccentricities
0.1 in a swarm of such giant impact ejecta. Although the total mass of giant
impact ejecta decreases by a factor of 3 in 30 Myrs, eccentricities of planets
are damped down to the Earth level (~0.01) due to interaction with giant impact
ejecta. Therefore, giant impact ejecta play an important role for determination
of terrestrial planet orbits.",1911.00278v3
2019-11-06,Damping in Ru/Co-based multilayer films with large Dzyaloshinskii-Moriya interaction,"Recent development of the magnetic material engineering led to achievement of
the systems with a high interfacial Dzyaloshinskii-Moriya interaction (DMI). As
a result, the formation of non-collinear magnetic soliton states or
nonreciprocal spin wave dynamics is achievable. Typically used materials are
based on bi-layers Heavy Metal/Ferromagnet, e.g., Pt/Co. These layers are
characterized not only by a strong DMI, but also by the spin pumping effect and
the resulting relatively large damping. Here, we show that the considerable
interfacial DMI can be also present in bi-layers based on Ru/Co, characterized
with low spin pumping effect and low damping. It is therefore a good candidate
for the dynamical studies and implementations of chiral DMI. It is demonstrated
by theoretical calculations that the value of DMI can be strongly affected and
controlled by the strain of the lattice. We show a systematic experimental and
theoretical comparison of magnetic material parameters between Pt/Co and Ru/Co
bi-layers as a deserving candidate for spintronic and spin-orbitronic
applications.",1911.02467v1
2019-11-14,Studies of the beam-ion instability and its mitigation with feedback system,"The beam-ion interaction is a potential limitation of beam performance in
electron accelerators, especially where the beam emittance is of a great
concern in future ultra-low emittance light source. ""Conventionally"", the beam
instability due to beam-ion interaction is attributed to two types of effects:
ion trapping effect and fast ion effect, which emphasize the beam-ion dynamics
in different time scales. Whereas, in accelerators, the beam suffers from a
mixture of ion trapping effect and fast ion effect, leading to a more
complicated process and requiring a self-consistent treatment. To evaluate the
beam characteristics, as emittance growth under the influence from beam-ion
effect, a new numerical simulation code based on the ""quasi-strong-strong""
model has been developed, including modules of ionization, beam-ion
interaction, synchrotron radiation damping, quantum excitation, bunch-by-bunch
feedback, etc. In the study, we do not regularly distinguish the ion trapping
effect and the fast ion effect, but treat beam-ion interaction more generally
and consistently. The lattice of High Energy Photon Source, a diffraction limit
ring under construction in Beijing, is used as an example to show the beam-ion
effect. It is found that in this low emittance ring, the beam-ion instability
is not a dominant mechanism in operation mode with a high beam current, but
seriously occurs in a lower beam current region. When the beam-ion instability
were significantly driven and can not be damped by the synchrotron radiation
damping, the simulations show the bunch-by-bunch feedback system based on the
Finite Impulse Response filter technique can be adopted to mitigate it
effectively.",1911.05958v1
2019-12-05,Steering magnonic dynamics and permeability at exceptional points in a parity-time symmetric waveguide,"Tuning the low-energy magnetic dynamics is a key element in designing novel
magnetic metamaterials, spintronic devices and magnonic logic circuits. This
study uncovers a new, highly effective way of controlling the magnetic
permeability via shaping the magnonic properties in coupled magnetic waveguides
separated by current carrying spacer with strong spin-orbit coupling. The
spin-orbit torques exerted on the waveguides leads to an externally tunable
enhancement of magnetic damping in one waveguide and a decreased damping in the
other, constituting so a magnetic parity-time (PT) symmetric system with
emergent magnetic properties at the verge of the exceptional point where
magnetic gains/losses are balanced. In addition to controlling the magnetic
permeability, phenomena inherent to PT-symmetric systems are identified,
including the control on magnon power oscillations, nonreciprocal magnon
propagation, magnon trapping and enhancement as well as the increased
sensitivity to magnetic perturbation and abrupt spin reversal. These
predictions are demonstrated analytically and confirmed by full numerical
simulations under experimentally feasible conditions. The position of the
exceptional points and the strength of the spontaneous PT symmetry breaking can
be tuned by external electric and/or magnetic fields. The roles of the
intrinsic magnetic damping, and the possibility of an electric control via
Dzyaloshinskii-Moriya interaction are exposed and utilized for mode dispersion
shaping and magnon amplification and trapping. The results point to a new route
to designing optomagnonic waveguides, traps, sensors, and circuits.",1912.02500v1
2020-03-03,Linear stability analysis for 2D shear flows near Couette in the isentropic Compressible Euler equations,"In this paper, we investigate linear stability properties of the 2D
isentropic compressible Euler equations linearized around a shear flow given by
a monotone profile, close to the Couette flow, with constant density, in the
domain $\mathbb{T}\times \mathbb{R}$. We begin by directly investigating the
Couette shear flow, where we characterize the linear growth of the compressible
part of the fluid while proving time decay for the incompressible part
(inviscid damping with slower rates). Then we extend the analysis to monotone
shear flows near Couette, where we are able to give an upper bound, superlinear
in time, for the compressible part of the fluid. The incompressible part enjoys
an inviscid damping property, analogous to the Couette case. In the pure
Couette case, we exploit the presence of an additional conservation law (which
connects the vorticity and the density on the moving frame) in order to reduce
the number of degrees of freedom of the system. The result then follows by
using weighted energy estimates. In the general case, unfortunately, this
conservation law no longer holds. Therefore we define a suitable weighted
energy functional for the whole system, which can be used to estimate the
irrotational component of the velocity but does not provide sharp bounds on the
solenoidal component. However, even in the absence of the aforementioned
additional conservation law, we are still able to show the existence of a
functional relation which allows us to recover somehow the vorticity from the
density, on the moving frame. By combining the weighted energy estimates with
the functional relation we also recover the inviscid damping for the solenoidal
component of the velocity.",2003.01694v1
2020-03-06,Lattice dynamics and polarization-dependent phonon damping in $α$-phase FeSi$_{2}$ nanoislands,"We determined the lattice dynamics of metastable, surface-stabilized
$\alpha$-phase FeSi$_2$ nanoislands epitaxially grown on the Si(111) surface
with average heights and widths ranging from 1.5 to 20 nm and 18 to 72 nm,
respectively. The crystallographic orientation, surface morphology and local
crystal structure of the nanoislands were investigated by reflection
high-energy electron diffraction, atomic force microscopy and X-ray absorption
spectroscopy. The Fe-partial phonon density of states (PDOS), obtained by
nuclear inelastic scattering, exhibits a pronounced damping and broadening of
the spectral features with decreasing average island height. First-principles
calculations of the polarization-projected Si- and Fe-partial phonon
dispersions and PDOS enable the disentanglement of the contribution of the
$xy$- and $z$-polarized phonons to the experimental PDOS. Modeling of the
experimental data with the theoretical results unveils an enhanced damping of
the $z$-polarized phonons for islands with average sizes below 10 nm. This
phenomenon is attributed to the fact that the low-energy $z$-polarized phonons
couple to the low-energy surface/interface vibrational modes. The thermodynamic
and elastic properties obtained from the experimental data show a pronounced
size-dependent behavior.",2003.02969v1
2020-03-20,The resonant drag instability of dust streaming in turbulent protoplanetary disc,"Damping of the previously discovered resonant drag instability (RDI) of dust
streaming in protoplanetary disc is studied using the local approach to
dynamics of gas-dust perturbations in the limit of the small dust fraction.
Turbulence in a disc is represented by the effective viscosity and diffusivity
in equations of motion for gas and dust, respectively. In the standard case of
the Schmidt number (ratio of the effective viscosity to diffusivity) Sc = 1,
the reduced description of RDI in terms of the inertial wave (IW) and the
streaming dust wave (SDW) falling in resonance with each other reveals that
damping solution differs from the inviscid solution simply by adding the
characteristic damping frequency to its growth rate. RDI is fully suppressed at
the threshold viscosity, which is estimated analytically, first, for radial
drift, next, for vertical settling of dust, and at last, in the case of
settling combined with radial drift of the dust. In the last case, RDI survives
up to the highest threshold viscosity, with a greater excess for smaller
solids. Once Sc \neq 1, a new instability specific for dissipative
perturbations on the dust settling background emerges. This instability of the
quasi-resonant nature is referred to as settling viscous instability (SVI). The
mode akin to SDW (IW) becomes growing in a region of long waves provided that
Sc > 1 (Sc < 1). SVI leads to an additional increase of the threshold
viscosity.",2003.09212v1
2020-05-22,"Quasinormal modes, shadow and greybody factors of 5D electrically charged Bardeen black holes","We study quasinormal modes (QNMs) in 5D electrically charged Bardeen black
holes spacetime by considering the scalar and electromagnetic field
perturbations. The black holes spacetime is an exact solution of Einstein
gravity coupled to nonlinear electrodynamics in five dimensions, which has
nonsingular behavior. To calculate QNMs, we use the WKB approximation method up
to sixth order. Due to the presence of electric charge $q_e > 0$, both the
scalar and electromagnetic field perturbations decay more slowly when compared
to the Schwarzschild-Tangherlini black holes. We discover that the scalar field
perturbations oscillate more rapidly when compared to the electromagnetic field
perturbations. In terms of damping, the scalar field perturbations damp more
quickly. Graphically we show that the transmission (reflection) coefficients
decrease (increase) with an increase in the magnitude of the electric charge
$q_e$. The emission of gravitational waves allows spacetime to undergo damped
oscillations due to the nonzero value of the imaginary part, which is always
negative. The imaginary part of the QNMs frequencies is continuously decreasing
with an increase in the magnitude of the electric charge $q_e$ for a given mode
($l,n$). A connection between the QNMs frequencies and the black hole shadow,
as well as the geometric cross-section in the eikonal limit, is also described.",2005.11080v2
2020-05-27,Role of diffusive surface scattering in nonlocal plasmonics,"The recent generalised nonlocal optical response (GNOR) theory for plasmonics
is analysed, and its main input parameter, namely the complex hydrodynamic
convection-diffusion constant, is quantified in terms of enhanced Landau
damping due to diffusive surface scattering of electrons at the surface of the
metal. GNOR has been successful in describing plasmon damping effects, in
addition to the frequency shifts originating from induced-charge screening,
through a phenomenological electron diffusion term implemented into the
traditional hydrodynamic Drude model of nonlocal plasmonics. Nevertheless, its
microscopic derivation and justification is still missing. Here we discuss how
the inclusion of a diffusion-like term in standard hydrodynamics can serve as
an efficient vehicle to describe Landau damping without resorting to
computationally demanding quantum-mechanical calculations, and establish a
direct link between this term and the Feibelman $d$ parameter for the centroid
of charge. Our approach provides a recipe to connect the phenomenological
fundamental GNOR parameter to a frequency-dependent microscopic
surface-response function. We therefore tackle one of the principal limitations
of the model, and further elucidate its range of validity and limitations, thus
facilitating its proper application in the framework of nonclassical
plasmonics.",2005.13218v2
2020-05-28,Spintronics meets nonadiabatic molecular dynamics: Geometric spin torque and damping on noncollinear classical magnetism due to electronic open quantum system,"We analyze a quantum-classical hybrid system of steadily precessing slow
classical localized magnetic moments, forming a head-to-head domain wall,
embedded into an open quantum system of fast nonequilibrium electrons. The
electrons reside within a metallic wire connected to macroscopic reservoirs.
The model captures the essence of dynamical noncollinear and noncoplanar
magnetic textures in spintronics, while making it possible to obtain the exact
time-dependent nonequilibrium density matrix of electronic system and split it
into four contributions. The Fermi surface contribution generates dissipative
(or damping-like in spintronics terminology) spin torque on the moments, and
one of the two Fermi sea contributions generates geometric torque dominating in
the adiabatic regime. When the coupling to the reservoirs is reduced, the
geometric torque is the only nonzero contribution. Locally it has both
nondissipative (or field-like in spintronics terminology) and damping-like
components, but with the sum of latter being zero, which act as the
counterparts of geometric magnetism force and electronic friction in
nonadiabatic molecular dynamics. Such current-independent geometric torque is
absent from widely used micromagnetics or atomistic spin dynamics modeling of
magnetization dynamics based on the Landau-Lifshitz-Gilbert equation, where
previous analysis of Fermi surface-type torque has severely underestimated its
magnitude.",2005.14153v2
2020-08-18,A Quasi-Linear Diffusion Model for Resonant Wave-Particle Instability in Homogeneous Plasma,"In this paper, we develop a model to describe the generalized wave-particle
instability in a quasi-neutral plasma. We analyze the quasi-linear diffusion
equation for particles by expressing an arbitrary unstable and resonant wave
mode as a Gaussian wave packet, allowing for an arbitrary direction of
propagation with respect to the background magnetic field. We show that the
localized energy density of the Gaussian wave packet determines the
velocity-space range in which the dominant wave-particle instability and
counter-acting damping contributions are effective. Moreover, we derive a
relation describing the diffusive trajectories of resonant particles in
velocity space under the action of such an interplay between the wave-particle
instability and damping. For the numerical computation of our theoretical
model, we develop a mathematical approach based on the Crank-Nicolson scheme to
solve the full quasi-linear diffusion equation. Our numerical analysis solves
the time evolution of the velocity distribution function under the action of a
dominant wave-particle instability and counteracting damping and shows a good
agreement with our theoretical description. As an application, we use our model
to study the oblique fast-magnetosonic/whistler instability, which is proposed
as a scattering mechanism for strahl electrons in the solar wind. In addition,
we numerically solve the full Fokker-Planck equation to compute the time
evolution of the electron-strahl distribution function under the action of
Coulomb collisions with core electrons and protons after the collisionless
action of the oblique fast-magnetosonic/whistler instability.",2008.08169v2
2020-09-10,Spin waves in alloys at finite temperatures: application for FeCo magnonic crystal,"We study theoretically the influence of the temperature and disorder on the
spin wave spectrum of the magnonic crystal Fe$_{1-c}$Co$_{c}$. Our formalism is
based on the analysis of a Heisenberg Hamiltonian by means of the wave vector
and frequency dependent transverse magnetic susceptibility. The exchange
integrals entering the model are obtained from the \emph{ab initio} magnetic
force theorem. The coherent potential approximation is employed to treat the
disorder and random phase approximation in order to account for the softening
of the magnon spectrum at finite temperatures. The alloy turns out to exhibit
many advantageous properties for spintronic applications. Apart from high Curie
temperature, its magnonic bandgap remains stable at elevated temperatures and
is largely unaffected by the disorder. We pay particular attention to the
attenuation of magnons introduced by the alloying. The damping turns out to be
a non-monotonic function of the impurity concentration due to the non-trivial
evolution of the value of exchange integrals with the Co concentration. The
disorder induced damping of magnons is estimated to be much smaller than their
Landau damping.",2009.04712v6
2020-09-14,On the response of a star cluster to a tidal perturbation,"We study the response of star clusters to individual tidal perturbations
using controlled $N$-body simulations. We consider perturbations by a moving
point mass and by a disc, and vary the duration of the perturbation as well as
the cluster density profile. For fast perturbations (i.e. `shocks'), the
cluster gains energy in agreement with theoretical predictions in the impulsive
limit. For slow disc perturbations, the energy gain is lower, and this has
previously been attributed to adiabatic damping. However, the energy gain due
to slow perturbations by a point-mass is similar to, or larger than that due to
fast shocks, which is not expected because adiabatic damping should be almost
independent of the nature of the tides. We show that the geometric distortion
of the cluster during slow perturbations is of comparable importance for the
energy gain as adiabatic damping, and that the combined effect can
qualitatively explain the results. The half-mass radius of the bound stars
after a shock increases up to $\sim$7\% for low-concentration clusters, and
decreases $\sim$3\% for the most concentrated ones. The fractional mass loss is
a non-linear function of the energy gain, and depends on the nature of the
tides and most strongly on the cluster density profile, making semi-analytic
model predictions for cluster lifetimes extremely sensitive to the adopted
density profile.",2009.06643v2
2020-09-18,African Easterly Waves in an Idealized General Circulation Model: Instability and Wavepacket Diagnostics,"We examine the group dynamic of African easterly waves (AEW) generated in a
realistic, spatially non-homogeneous African easterly jet (AEJ) using an
idealized general circulation model. Our objective is to investigate whether
the limited zonal extent of the AEJ is an impediment to AEW development. We
construct a series of basic states using global reanalysis fields and
initialize waves via transient heating over West Africa. The dominant response
is a localized wavepacket that disperses upstream and downstream. The inclusion
of a crude representation of boundary layer damping stabilizes the waves in
most cases. In some basic states, however, exponential growth occurs even in
the presence of damping. This shows that AEWs can occasionally emerge
spontaneously. The key result is that the wavepacket in almost all cases
remains within the AEJ instead of being swept away. Drawing from other studies,
this also suggests that even the damped waves can grow if coupled with
additional sources of energy such as moist convection and dust radiative
feedback. The wavepacket in the localized AEJ appears to satisfy a condition
for absolute instability, a form of spatial hydrodynamic instability. However,
this needs to be verified more rigorously. Our results also suggest that the
intermittent nature of AEWs is mediated, not by transitions between convective
and absolute instability, but likely by external sources such as propagating
equatorial wave modes",2009.08604v1
2020-09-25,Polaronic Contributions to Friction in a Manganite Thin Film,"Despite the huge importance of friction in regulating movement in all natural
and technological processes, the mechanisms underlying dissipation at a sliding
contact are still a matter of debate. Attempts to explain the dependence of
measured frictional losses at nanoscale contacts on the electronic degrees of
freedom of the surrounding materials have so far been controversial. Here, it
is proposed that friction can be explained by considering damping of stick-slip
pulses in a sliding contact. Based on friction force microscopy studies of
La$_{(1-x)}$Sr$_x$MnO$_3$ films at the ferromagnetic-metallic to
paramagnetic-polaronic conductor phase transition, it is confirmed that the
sliding contact generates thermally-activated slip pulses in the nanoscale
contact, and argued that these are damped by direct coupling into phonon bath.
Electron-phonon coupling leads to the formation of Jahn-Teller polarons and a
clear increase in friction in the high temperature phase. There is no evidence
for direct electronic drag on the atomic force microscope tip nor any
indication of contributions from electrostatic forces. This intuitive scenario,
that friction is governed by the damping of surface vibrational excitations,
provides a basis for reconciling controversies in literature studies as well as
suggesting possible tactics for controlling friction.",2009.12137v1
2020-09-25,Direct computation of nonlinear mapping via normal form for reduced-order models of finite element nonlinear structures,"The direct computation of the third-order normal form for a geometrically
nonlinear structure discretised with the finite element (FE) method, is
detailed. The procedure allows to define a nonlinear mapping in order to derive
accurate reduced-order models (ROM) relying on invariant manifold theory. The
proposed reduction strategy is direct and simulation free, in the sense that it
allows to pass from physical coordinates (FE nodes) to normal coordinates,
describing the dynamics in an invariant-based span of the phase space. The
number of master modes for the ROM is not a priori limited since a complete
change of coordinate is proposed. The underlying theory ensures the quality of
the predictions thanks to the invariance property of the reduced subspace,
together with their curvatures in phase space that accounts for the nonresonant
nonlinear couplings. The method is applied to a beam discretised with 3D
elements and shows its ability in recovering internal resonance at high energy.
Then a fan blade model is investigated and the correct prediction given by the
ROMs are assessed and discussed. A method is proposed to approximate an
aggregate value for the damping, that takes into account the damping
coefficients of all the slave modes, and also using the Rayleigh damping model
as input. Frequency-response curves for the beam and the blades are then
exhibited, showing the accuracy of the proposed method.",2009.12145v1
2020-09-29,Structural Phase Dependent Giant Interfacial Spin Transparency in W/CoFeB Thin Film Heterostructure,"Pure spin current has transfigured the energy-efficient spintronic devices
and it has the salient characteristic of transport of the spin angular
momentum. Spin pumping is a potent method to generate pure spin current and for
its increased efficiency high effective spin-mixing conductance (Geff) and
interfacial spin transparency (T) are essential. Here, a giant T is reported in
Sub/W(t)/Co20Fe60B20(d)/SiO2(2 nm) heterostructures in \beta-tungsten (\beta-W)
phase by employing all-optical time-resolved magneto-optical Kerr effect
technique. From the variation of Gilbert damping with W and CoFeB thicknesses,
the spin diffusion length of W and spin-mixing conductances are extracted.
Subsequently, T is derived as 0.81 \pm 0.03 for the \beta-W/CoFeB interface. A
sharp variation of Geff and T with W thickness is observed in consonance with
the thickness-dependent structural phase transition and resistivity of W. The
spin memory loss and two-magnon scattering effects are found to have negligible
contributions to damping modulation as opposed to spin pumping effect which is
reconfirmed from the invariance of damping with Cu spacer layer thickness
inserted between W and CoFeB. The observation of giant interfacial spin
transparency and its strong dependence on crystal structures of W will be
important for pure spin current based spin-orbitronic devices.",2009.14143v1
2020-10-08,Modeling of the ECCD injection effect on the Heliotron J and LHD plasma stability,"The aim of the study is to analyze the stability of the Energetic Particle
Modes (EPM) and Alfven Eigenmodes (AE) in Helitron J and LHD plasma if the
electron cyclotron current drive (ECCD) is applied. The analysis is performed
using the code FAR3d that solves the reduced MHD equations describing the
linear evolution of the poloidal flux and the toroidal component of the
vorticity in a full 3D system, coupled with equations of density and parallel
velocity moments for the energetic particle (EP) species, including the effect
of the acoustic modes. The Landau damping and resonant destabilization effects
are added via the closure relation. The simulation results show that the n=1
EPM and n=2 Global AE (GAE) in Heliotron J plasma can be stabilized if the
magnetic shear is enhanced at the plasma periphery by an increase (co-ECCD
injection) or decrease (ctr-ECCD injection) of the rotational transform at the
magnetic axis iota0. In the ctr-ECCD simulations, the EPM/AE growth rate
decreases only below a given iota0, similar to the ECCD intensity threshold
observed in the experiments. In addition, ctr-ECCD simulations show an
enhancement of the continuum damping. The simulations of the LHD discharges
with ctr-ECCD injection indicate the stabilization of the n=1 EPM, n=2 Toroidal
AE (TAE) and n=3 TAE, caused by an enhancement of the continuum damping in the
inner plasma leading to a higher EP beta threshold with respect to the co- and
no-ECCD simulations.",2010.03892v1
2020-10-08,A blow-up result for the wave equation with localized initial data: the scale-invariant damping and mass term with combined nonlinearities,"We are interested in this article in studying the damped wave equation with
localized initial data, in the \textit{scale-invariant case} with mass term and
two combined nonlinearities. More precisely, we consider the following
equation: $$ (E) {1cm} u_{tt}-\Delta
u+\frac{\mu}{1+t}u_t+\frac{\nu^2}{(1+t)^2}u=|u_t|^p+|u|^q, \quad \mbox{in}\
\mathbb{R}^N\times[0,\infty), $$ with small initial data. Under some
assumptions on the mass and damping coefficients, $\nu$ and $\mu>0$,
respectively, we show that blow-up region and the lifespan bound of the
solution of $(E)$ remain the same as the ones obtained in \cite{Our2} in the
case of a mass-free wave equation, it i.e. $(E)$ with $\nu=0$.
  Furthermore, using in part the computations done for $(E)$, we enhance the
result in \cite{Palmieri} on the Glassey conjecture for the solution of $(E)$
with omitting the nonlinear term $|u|^q$. Indeed, the blow-up region is
extended from $p \in (1, p_G(N+\sigma)]$, where $\sigma$ is given by (1.12)
below, to $p \in (1, p_G(N+\mu)]$ yielding, hence, a better estimate of the
lifespan when $(\mu-1)^2-4\nu^2<1$. Otherwise, the two results coincide.
Finally, we may conclude that the mass term {\it has no influence} on the
dynamics of $(E)$ (resp. $(E)$ without the nonlinear term $|u|^q$), and the
conjecture we made in \cite{Our2} on the threshold between the blow-up and the
global existence regions obtained holds true here.",2010.05455v1
2020-10-14,Kink Oscillations in Solar Coronal Loops with Elliptical Cross-Sections. I. the linear regime,"The cross sections of solar coronal loops are suggested to be rarely
circular. We examine linear kink oscillations in straight, density-enhanced,
magnetic cylinders with elliptical cross-sections by solving the
three-dimensional magnetohydrodynamic equations from an initial-value-problem
perspective. Motivated by relevant eigen-mode analyses, we distinguish between
two independent polarizations, one along the major axis (the M-modes) and the
other along the minor one (the m-modes). We find that, as happens for coronal
loops with circular cross-sections, the apparent damping of the transverse
displacement of the loop axis is accompanied by the accumulation of transverse
Alfv\'enic motions and the consequent development of small-scales therein,
suggesting the robustness of the concepts of resonant absorption and
phase-mixing. In addition, two stages can in general be told apart in the
temporal evolution of the loop displacement; a Gaussian time dependence
precedes an exponential one. For the two examined density ratios between loops
and their surroundings, the periods of the M-modes (m-modes) tend to increase
(decrease) with the major-to-minor-half-axis ratio, and the damping times in
the exponential stage for the M-modes tend to exceed their m-mode counterparts.
This is true for the two transverse profiles we examine. However, the relative
magnitudes of the damping times in the exponential stage for different
polarizations depend on the specification of the transverse profile and/or the
density contrast. The applications of our numerical findings are discussed in
the context of coronal seismology.",2010.06991v1
2020-11-04,The impact of astrophysical dust grains on the confinement of cosmic rays,"We argue that charged dust grains could significantly impact the confinement
and transport of galactic cosmic rays. For sub-GeV to ~1000GeV cosmic rays,
small-scale parallel Alfv\'en waves, which isotropize cosmic rays through
gyro-resonant interactions, are also gyro-resonant with charged grains. If the
dust is nearly stationary, as in the bulk of the interstellar medium, Alfv\'en
waves are damped by dust. This will reduce the amplitude of Alfv\'en waves
produced by the cosmic rays through the streaming instability, thus enhancing
cosmic-ray transport. In well-ionized regions, the dust damping rate is larger
by a factor of ~10 than other mechanisms that damp parallel Alfv\'en waves at
the scales relevant for ~GeV cosmic rays, suggesting that dust could play a key
role in regulating cosmic-ray transport. In astrophysical situations in which
the dust moves through the gas with super-Alfv\'enic velocities, Alfv\'en waves
are rendered unstable, which could directly scatter cosmic rays. This
interaction has the potential to create a strong feedback mechanism where dust,
driven through the gas by radiation pressure, then strongly enhances the
confinement of cosmic rays, increasing their capacity to drive outflows. This
mechanism may act in the circumgalactic medium around star-forming galaxies and
active galactic nuclei.",2011.02497v2
2020-11-17,A Phase Resonance Approach for Modal Testing of Structures with Nonlinear Dissipation,"The concept of nonlinear modes is useful for the dynamical characterization
of nonlinear mechanical systems. While efficient and broadly applicable methods
are now available for the computation of nonlinear modes, nonlinear modal
testing is still in its infancy. The purpose of this work is to overcome its
present limitation to conservative nonlinearities. Our approach relies on the
recently extended periodic motion concept, according to which nonlinear modes
of damped systems are defined as family of periodic motions induced by an
appropriate artificial excitation that compensates the natural dissipation. The
particularly simple experimental implementation with only a single-point,
single-frequency, phase resonant forcing is analyzed in detail. The method
permits the experimental extraction of natural frequencies, modal damping
ratios and deflection shapes (including harmonics), for each mode of interest,
as function of the vibration level. The accuracy, robustness and current
limitations of the method are first demonstrated numerically. The method is
then verified experimentally for a friction-damped system. Moreover, a
self-contained measure for estimating the quality of the extracted modal
properties is investigated. The primary advantages over alternative vibration
testing methods are noise robustness, broad applicability and short measurement
duration. The central limitation of the identified modal quantities is that
they only characterize the system in the regime near isolated resonances.",2011.08500v1
2021-03-08,"A Self-Consistent, Time-Dependent Treatment of Dynamical Friction: New Insights regarding Core Stalling and Dynamical Buoyancy","Dynamical friction is typically regarded a secular process, in which the
subject ('perturber') evolves very slowly (secular approximation), and has been
introduced to the host over a long time (adiabatic approximation). These
assumptions imply that dynamical friction arises from the LBK torque with
non-zero contribution only from pure resonance orbits. However, dynamical
friction is only of astrophysical interest if its timescale is shorter than the
age of the Universe. In this paper we therefore relax the adiabatic and secular
approximations. We first derive a generalized LBK torque, which reduces to the
LBK torque in the adiabatic limit, and show that it gives rise to transient
oscillations due to non-resonant orbits that slowly damp out, giving way to the
LBK torque. This is analogous to how a forced, damped oscillator undergoes
transients before settling to a steady state, except that here the damping is
due to phase mixing rather than dissipation. Next, we present a self-consistent
treatment, that properly accounts for time-dependence of the perturber
potential and circular frequency (memory effect), which we use to examine
orbital decay in a cored galaxy. We find that the memory effect results in a
phase of accelerated, super-Chandrasekhar friction before the perturber stalls
at a critical radius, $R_{\mathrm{crit}}$, in the core (core-stalling). Inside
of $R_{\mathrm{crit}}$ the torque flips sign, giving rise to dynamical
buoyancy, which counteracts friction and causes the perturber to stall. This
phenomenology is consistent with $N$-body simulations, but has thus far eluded
proper explanation.",2103.05004v1
2021-03-26,First-order strong-field QED processes including the damping of particles states,"Volkov states are exact solutions of the Dirac equation in the presence of an
arbitrary plane wave. Volkov states, as well as free photon states, are not
stable in the presence of the background plane-wave field but ""decay"" as
electrons/positrons can emit photons and photons can transform into
electron-positron pairs. By using the solutions of the corresponding
Schwinger-Dyson equations within the locally-constant field approximation, we
compute the probabilities of nonlinear single Compton scattering and nonlinear
Breit-Wheeler pair production by including the effects of the decay of
electron, positron, and photon states. As a result, we find that the
probabilities of these processes can be expressed as the integral over the
light-cone time of the known probabilities valid for stable states per unit of
light-cone time times a light-cone time-dependent exponential damping function
for each interacting particle. The exponential function for an incoming
(outgoing) either electron/positron or photon at each light-cone time
corresponds to the total probability that either the electron/positron emits a
photon via nonlinear Compton scattering or the photon transforms into an
electron-positron pair via nonlinear Breit-Wheeler pair production until that
light-cone time (from that light-cone time on). It is interesting that the
exponential damping terms depend not only on the particles momentum but also on
their spin (for electrons/positrons) and polarization (for photons). This
additional dependence on the discrete quantum numbers prevents the application
of the electron/positron spin and photon polarization sum-rules, which
significantly simplify the computations in the perturbative regime.",2103.14637v1
2021-04-10,Non-Markovian open quantum system approach to the early universe: I. Damping of gravitational waves by matter,"By revising the application of the open quantum system approach to the early
universe and extending it to the conditions beyond the Markovian approximation,
we obtain a new non-Markovian quantum Boltzmann equation. Throughout the paper,
we also develop an extension of the quantum Boltzmann equation to describe the
processes that are irreversible at the macroscopic level. This new kinetic
equation is, in principle, applicable to a wide variety of processes in the
early universe. For instance, using this equation one can accurately study the
microscopic influence of a cosmic environment on a system of cosmic background
photons or stochastic gravitational waves. In this paper, we apply the
non-Markovian quantum Boltzmann equation to study the damping of gravitational
waves propagating in a medium consisting of decoupled ultra-relativistic
neutrinos. For such a system, we study the time evolution of the intensity and
the polarization of the gravitational waves. It is shown that, in contrast to
intensity and linear polarization which are damped, the circular polarization
(V-mode) of the gravitational wave (if present) is amplified by propagating
through such a medium.",2104.04836v2
2021-04-19,Giant spin-orbit torque efficiency in all-epitaxial heterostructures,"A large anti-damping spin-obit torque (SOT) efficiency in magnetic
heterostructures is a prerequisite to realize energy efficient spin torque
based magnetic memories and logic devices. The efficiency can be characterized
in terms of the spin-orbit fields generated by anti-damping torques when an
electric current is passed through the non-magnetic layer. We report a giant
spin-orbit field of 48.96 (27.50) mT at an applied current density of 1 MAcm-2
in beta-W interfaced Co60Fe40 (Ni81Fe19)/TiN epitaxial structures due to an
anti-damping like torque, which results in a magnetization auto-oscillation
current density as low as 1.68(3.27) MAcm-2. The spin-orbit field value
increases with decrease of beta-W layer thickness, which affirms that epitaxial
surface states are responsible for the extraordinary large efficiency. SOT
induced energy efficient in-plane magnetization switching in large 20x100 um2
structures has been demonstrated by Kerr microscopy and the findings are
supported by results from micromagnetic simulations. The observed giant SOT
efficiencies in the studied all-epitaxial heterostructures are comparable to
values reported for topological insulators. These results confirm that by
utilizing epitaxial material combinations an extraordinary large SOT efficiency
can be achieved using semiconducting industry compatible 5d heavy metals, which
provides immediate solutions for the realization of energy efficient spin-logic
devices.",2104.09168v1
2021-06-10,Constraining extra dimensions using observations of black hole quasi-normal modes,"The presence of extra dimensions generically modify the spacetime geometry of
a rotating black hole, by adding an additional hair, besides the mass $M$ and
the angular momentum $J$, known as the `tidal charge' parameter, $\beta$. In a
braneworld scenario with one extra spatial dimension, the extra dimension is
expected to manifest itself through -- (a) negative values of $\beta$, and (b)
modified gravitational perturbations. This in turn would affect the
quasi-normal modes of rotating black holes. We numerically solve the perturbed
gravitational field equations using the continued fractions method and
determine the quasi-normal mode spectra for the braneworld black hole. We find
that increasingly negative values of $\beta$ correspond to a diminishing
imaginary part of the quasi-normal mode, or equivalently, an increasing damping
time. Using the publicly available data of the properties of the remnant black
hole in the gravitational wave signal GW150914, we check for consistency
between the predicted values (for a given $\beta$) of the frequency and damping
time of the least-damped $\ell=2,m=2$ quasi-normal mode and measurements of
these quantities using other independent techniques. We find that it is highly
unlikely for the tidal charge, $\beta \lesssim -0.05$, providing a conservative
limit on the tidal charge parameter. Implications and future directions are
discussed.",2106.05558v2
2021-06-24,A Polarizable Water Potential Derived from a Model Electron Density,"A new empirical potential for efficient, large scale molecular dynamics
simulation of water is presented. The HIPPO (Hydrogen-like Intermolecular
Polarizable POtential) force field is based upon the model electron density of
a hydrogen-like atom. This framework is used to derive and parameterize
individual terms describing charge penetration damped permanent electrostatics,
damped polarization, charge transfer, anisotropic Pauli repulsion, and damped
dispersion interactions. Initial parameter values were fit to Symmetry Adapted
Perturbation Theory (SAPT) energy components for ten water dimer
configurations, as well as the radial and angular dependence of the canonical
dimer. The SAPT-based parameters were then systematically refined to extend the
treatment to water bulk phases. The final HIPPO water model provides a balanced
representation of a wide variety of properties of gas phase clusters, liquid
water and ice polymorphs, across a range of temperatures and pressures. This
water potential yields a rationalization of water structure, dynamics and
thermodynamics explicitly correlated with an ab initio energy decomposition,
while providing a level of accuracy comparable or superior to previous
polarizable atomic multipole force fields. The HIPPO water model serves as a
cornerstone around which similarly detailed physics-based models can be
developed for additional molecular species.",2106.13116v3
2021-07-19,Long term behavior of 2D and 3D non-autonomous random convective Brinkman-Forchheimer equations driven by colored noise,"The long time behavior of Wong-Zakai approximations of 2D as well as 3D
non-autonomous stochastic convective Brinkman-Forchheimer (CBF) equations with
non-linear diffusion terms on bounded and unbounded ($\mathbb{R}^d$ for
$d=2,3$) domains is discussed in this work. To establish the existence of
random pullback attractors, the concept of asymptotic compactness (AC) is used.
In bounded domains, AC is proved via compact Sobolev embeddings. In unbounded
domains, due to the lack of compact embeddings, the ideas of energy equations
and uniform tail estimates are exploited to prove AC. In the literature, CBF
equations are also known as \emph{Navier-Stokes equations (NSE) with damping},
and it is interesting to see that the modification in NSE by linear and
nonlinear damping provides better results than that available for NSE. The
presence of linear damping term helps to establish the results in the whole
domain $\mathbb{R}^d$. The nonlinear damping term supports to obtain better
results in 3D and also for a large class of nonlinear diffusion terms.
Moreover, we prove the existence of a unique random pullback attractor for
stochastic CBF equations with additive white noise. Finally, for additive as
well as multiplicative noise case, we establish the convergence of solutions
and upper semicontinuity of random pullback attractors for Wong-Zakai
approximations of stochastic CBF equations towards the random pullback
attractors for stochastic CBF equations when correlation time of colored noise
converges to zero.",2107.08890v1
2021-07-28,Queue-Channel Capacities with Generalized Amplitude Damping,"The generalized amplitude damping channel (GADC) is considered an important
model for quantum communications, especially over optical networks. We make two
salient contributions in this paper apropos of this channel. First, we consider
a symmetric GAD channel characterized by the parameter $n=1/2,$ and derive its
exact classical capacity, by constructing a specific induced classical channel.
We show that the Holevo quantity for the GAD channel equals the Shannon
capacity of the induced binary symmetric channel, establishing at once the
capacity result and that the GAD channel capacity can be achieved without the
use of entanglement at the encoder or joint measurements at the decoder.
Second, motivated by the inevitable buffering of qubits in quantum networks, we
consider a generalized amplitude damping \emph{queue-channel} -- that is, a
setting where qubits suffer a waiting time dependent GAD noise as they wait in
a buffer to be transmitted. This GAD queue channel is characterized by
non-i.i.d. noise due to correlated waiting times of consecutive qubits. We
exploit a conditional independence property in conjunction with additivity of
the channel model, to obtain a capacity expression for the GAD queue channel in
terms of the stationary waiting time in the queue. Our results provide useful
insights towards designing practical quantum communication networks, and
highlight the need to explicitly model the impact of buffering.",2107.13486v1
2021-07-31,Damped inertial dynamics with vanishing Tikhonov regularization: strong asymptotic convergence towards the minimum norm solution,"In a Hilbert space, we provide a fast dynamic approach to the hierarchical
minimization problem which consists in finding the minimum norm solution of a
convex minimization problem. For this, we study the convergence properties of
the trajectories generated by a damped inertial dynamic with Tikhonov
regularization. When the time goes to infinity, the Tikhonov regularization
parameter is supposed to tend towards zero, not too fast, which is a key
property to make the trajectories strongly converge towards the minimizer of
$f$ of minimum norm. According to the structure of the heavy ball method for
strongly convex functions, the viscous damping coefficient is proportional to
the square root of the Tikhonov regularization parameter. Therefore, it also
converges to zero, which will ensure rapid convergence of values. Precisely,
under a proper tuning of these parameters, based on Lyapunov's analysis, we
show that the trajectories strongly converge towards the minimizer of minimum
norm, and we provide the convergence rate of the values. We show a trade off
between the property of fast convergence of values, and the property of strong
convergence towards the minimum norm solution. This study improves several
previous works where this type of results was obtained under restrictive
hypotheses.",2108.00203v1
2021-08-11,Numerical investigation of the formation and stability of homogeneous pairs of soft particles in inertial microfluidics,"We investigate the formation and stability of a pair of identical soft
capsules in channel flow under mild inertia. We employ a combination of the
lattice Boltzmann, finite element and immersed boundary methods to simulate the
elastic particles in flow. Validation tests show excellent agreement with
numerical results obtained by other research groups. Our results reveal new
trajectory types that have not been observed for pairs of rigid particles.
While particle softness increases the likelihood of a stable pair forming, the
pair stability is determined by the lateral position of the particles. A key
finding is that stabilisation of the axial distance occurs after lateral
migration of the particles. During the later phase of pair formation, particles
undergo damped oscillations that are independent of initial conditions. These
damped oscillations are driven by a strong hydrodynamic coupling of the
particle dynamics, particle inertia and viscous dissipation. While the
frequency and damping coefficient of the oscillations depend on particle
softness, the pair formation time is largely determined by the initial particle
positions: the time to form a stable pair grows exponentially with the initial
axial distance. Our results demonstrate that particle softness has a strong
impact on the behaviour of particle pairs. The findings could have significant
ramifications for microfluidic applications where a constant and reliable axial
distance between particles is required, such as flow cytometry.",2108.05277v1
2021-08-13,Nonlinear modal testing of damped structures: Velocity feedback vs. phase resonance,"In recent years, a new method for experimental nonlinear modal analysis has
been developed, which is based on the extended periodic motion concept. The
method is well suited to experimentally obtain amplitude-dependent modal
properties (modal frequency, damping ratio and deflection shape) for strongly
nonlinear systems. To isolate a nonlinear mode, the negative viscous damping
term of the extended periodic motion concept is approximated by ensuring phase
resonance between excitation and response. In this work, an alternative
approach to isolate a nonlinear mode is developed and analyzed: velocity
feedback. The accuracy of the extracted modal properties and robustness of
velocity feedback is first assessed by means of simulated experiments. The two
approaches phase resonance and velocity feedback are then compared in terms of
accuracy and experimental implementation effort. To this end, both approaches
are applied to an experimental specimen, which is a cantilevered beam
influenced by a strong dry friction nonlinearity. In this work, the discussion
is limited to single-point excitation. It is shown that a robust implementation
of velocity feedback requires the measurement of several response signals,
distributed over the structure. An advantage of velocity feedback is that no
controller is needed. The accuracy of the modal properties can, however, suffer
from imperfections of the excitation mechanism such as a phase lag due to
exciter-structure interactions or gyroscopic forces due to single-point
excitation.",2108.06189v1
2021-09-21,Double diffusion structure of logarithmically damped wave equations with a small parameter,"We consider a wave equation with a nonlocal logarithmic damping depending on
a small parameter $\theta \in (0,1/2)$. This research is a counter part of that
was initiated by Charao-D'Abbicco-Ikehata considered in [5] for the large
parameter case $\theta \in (1/2,1)$. We study the Cauchy problem for this model
in the whole space for the small parameter case, and we obtain an asymptotic
profile and optimal estimates in time of solutions as time goes to infinity in
$L^2$-sense. An important discovery in this research is that in the one
dimensional case, we can present a threshold $\theta^{*} = 1/4$ of the
parameter $\theta$ such that the solution of the Cauchy problem decays with
some optimal rate for $\theta \in (0,\theta^{*})$, while the $L^2$-norm of the
corresponding solution blows up in infinite time for $\theta \in
[\theta^{*},1/2)$. The former (i.e., $\theta \in (0,\theta^{*})$ case)
indicates an usual diffusion phenomenon, while the latter (i.e., $\theta \in
[\theta^{*},1/2)$ case) implies, so to speak, a singular diffusion phenomenon.
Such a singular diffusion in the one dimensional case is a quite novel
phenomenon discovered through our new model produced by logarithmic damping
with a small parameter $\theta$.",2109.09944v2
2021-09-21,Non-intrusive Balancing Transformation of Highly Stiff Systems with Lightly-damped Impulse Response,"Balanced truncation (BT) is a model reduction method that utilizes a
coordinate transformation to retain eigen-directions that are highly observable
and reachable. To address realizability and scalability of BT applied to highly
stiff and lightly-damped systems, a non-intrusive data-driven method is
developed for balancing discrete-time systems via the eigensystem realization
algorithm (ERA). The advantage of ERA for balancing transformation makes
full-state outputs tractable. Further, ERA enables balancing despite stiffness,
by eliminating computation of balancing modes and adjoint simulations. As a
demonstrative example, we create balanced ROMs for a one-dimensional reactive
flow with pressure forcing, where the stiffness introduced by the chemical
source term is extreme (condition number $10^{13}$), preventing analytical
implementation of BT. We investigate the performance of ROMs in prediction of
dynamics with unseen forcing inputs and demonstrate stability and accuracy of
balanced ROMs in truly predictive scenarios whereas without ERA, POD-Galerkin
and Least-squares Petrov-Galerkin projections fail to represent the true
dynamics. We show that after the initial transients under unit impulse forcing,
the system undergoes lightly-damped oscillations, which magnifies the influence
of sampling properties on predictive performance of the balanced ROMs. We
propose an output domain decomposition approach and couple it with tangential
interpolation to resolve sharp gradients at reduced computational costs.",2109.10408v2
2021-10-08,Site characterization at Treasure Island and Delaney Park downhole arrays by heterogeneous data assimilation,"This article extends a recently proposed heterogeneous data assimilation
technique for site characterization to estimate compression and shear wave
velocity (Vp and Vs, respectively) and damping at Treasure Island and Delaney
Park downhole arrays. The adopted method is based on the joint inversion of
earthquake acceleration time series and experimental surface wave dispersion
data, and including physical constraints to improve the inverse problem's
well-posedness. We first use synthetic data at these two sites to refine the
proposed approach and then apply the refined algorithm to real data sets
available at the Treasure Island and Delaney Park downhole arrays. The joint
inversion results show that the estimated Vs and Vp profiles are in very good
agreement with measured profiles at these two sites. Our synthetic and real
data experiment results suggest that Vp estimation from inversion at downhole
arrays can be improved by integrating the water table depth information or the
higher modes of the Rayleigh wave dispersion data. Depending on the site
complexity, water table information can also help reduce uncertainties
associated with damping estimation. In the last part of this article, we
compare the performance of the inverted profiles to other methods used to
incorporate spatial variability and wave scattering effects in 1D ground
response analysis (GRA). The comparisons show that the joint inversion-based Vs
and Vp profiles and damping ratios estimated in this article can effectively
integrate the effects of spatial variability and wave scattering into 1D GRAs,
especially at the Delaney Park downhole array, which is classified as a poorly
modeled site using traditional 1D GRA.",2110.03849v1
2021-11-01,On the stochastic nature of Galactic cosmic-ray sources,"The precision measurements of the spectra of cosmic ray nuclei and leptons in
recent years have revealed the existence of multiple features, such as the
spectral break at $\sim 300$ GV rigidity seen by PAMELA and AMS-02 and more
recently confirmed by DAMPE and CALET, the softening in the spectra of H and He
nuclei at $\sim 10$ TV reported by DAMPE, confirming previous hints by NUCLEON
and CREAM, a tiny change of slope at $\sim 40$ GeV in the electron spectrum,
revealed by AMS-02, and the large spectral break at $\sim$ TeV reported by
indirect (HESS, MAGIC and VERITAS) and direct (DAMPE, CALET) measurements of
the total (electrons+positrons) lepton spectrum. In all these cases, the
possibility has been suggested that these features might reflect the occasional
presence of a local cosmic ray source, inducing a noticeable reshaping of the
average expected spectra. All these proposals have to face the question of how
likely it is for such a source to exist, a question that we address here in a
quantitative way. We study the statistical properties of random distribution of
sources in space and time, and the effect of the spiral structure of our Galaxy
for both the spectra of light nuclei (p and He) and leptons (electrons and
positrons) in different energy regions.",2111.01171v2
2021-11-09,The In Situ Signature of Cyclotron Resonant Heating,"The dissipation of magnetized turbulence is an important paradigm for
describing heating and energy transfer in astrophysical environments such as
the solar corona and wind; however, the specific collisionless processes behind
dissipation and heating remain relatively unconstrained by measurements. Remote
sensing observations have suggested the presence of strong temperature
anisotropy in the solar corona consistent with cyclotron resonant heating. In
the solar wind, in situ magnetic field measurements reveal the presence of
cyclotron waves, while measured ion velocity distribution functions have hinted
at the active presence of cyclotron resonance. Here, we present Parker Solar
Probe observations that connect the presence of ion-cyclotron waves directly to
signatures of resonant damping in observed proton-velocity distributions. We
show that the observed cyclotron wave population coincides with both flattening
in the phase space distribution predicted by resonant quasilinear diffusion and
steepening in the turbulent spectra at the ion-cyclotron resonant scale. In
measured velocity distribution functions where cyclotron resonant flattening is
weaker, the distributions are nearly uniformly subject to ion-cyclotron wave
damping rather than emission, indicating that the distributions can damp the
observed wave population. These results are consistent with active cyclotron
heating in the solar wind.",2111.05400v2
2021-11-10,Quantum amplitude damping for solving homogeneous linear differential equations: A noninterferometric algorithm,"In contexts where relevant problems can easily attain configuration spaces of
enormous sizes, solving Linear Differential Equations (LDEs) can become a hard
achievement for classical computers; on the other hand, the rise of quantum
hardware can conceptually enable such high-dimensional problems to be solved
with a foreseeable number of qubits, whilst also yielding quantum advantage in
terms of time complexity. Nevertheless, in order to bridge towards experimental
realizations with several qubits and harvest such potential in a short-term
basis, one must dispose of efficient quantum algorithms that are compatible
with near-term projections of state-of-the-art hardware, in terms of both
techniques and limitations. As the conception of such algorithms is no trivial
task, insights on new heuristics are welcomed. This work proposes a novel
approach by using the Quantum Amplitude Damping operation as a resource, in
order to construct an efficient quantum algorithm for solving homogeneous LDEs.
As the intended implementation involves performing Amplitude Damping
exclusively via a simple equivalent quantum circuit, our algorithm shall be
given by a gate-level quantum circuit (predominantly composed of elementary
2-qubit gates) and is particularly nonrestrictive in terms of connectivity
within and between some of its main quantum registers. We show that such an
open quantum system-inspired circuitry allows for constructing the real
exponential terms in the solution in a non-interferometric way; we also provide
a guideline for guaranteeing a lower bound on the probability of success for
each realization, by exploring the decay properties of the underlying quantum
operation.",2111.05646v2
2021-11-13,Attenuation of surface modes in granular media,"In this work, an unconsolidated granular medium, made of silica microbeads,
is experimentally tested in a laboratory setting. The objective is to
investigate the attenuation mechanisms of vertically polarized seismic waves
traveling at the surface of unconsolidated substrates that are characterized by
power-law rigidity profiles. Both geometric spreading and material damping due
to skeletal dissipation are considered. An electromagnetic shaker is employed
to excite the granular medium between 300 and 550 Hz, generating linear modes
that are localized near the surface. A densely sampled section is recorded at
the surface using a laser vibrometer. The explicit solution of the geometric
attenuation law of Rayleigh-like waves in layered media is employed to
calculate the geometric spreading function of the vertically polarized surface
modes within the granular material. In accordance with recent studies, the
dynamics of these small-amplitude multi-modal linear waves can be analysed by
considering the granular medium as perfectly continuous and elastic. By
performing a non-linear regression analysis on particle displacements,
extracted from experimental velocity data, we determine the frequency-dependent
attenuation coefficients, which account for the material damping.
  The findings of this work show that laboratory-scale physical models can be
used to study the geometric spreading of vertically polarized seismic waves
induced by the soil inhomogeneity and characterize the material damping of the
medium.",2111.07199v1
2021-11-15,The Interplay of Regularizing Factors in the Model of Upper Hybrid Oscillations of Cold Plasma,"A one-dimensional nonlinear model of the so-called upper hybrid oscillations
in a magnetoactive plasma is investigated taking into account electron-ion
collisions. It is known that both the presence of an external magnetic field of
strength $ B_0 $ and a sufficiently large collisional factor $ \nu $ help
suppress the formation of a finite-dimensional singularity in a solution
(breaking of oscillations). Nevertheless, the suppression mechanism is
different: an external magnetic field increases the oscillation frequency, and
collisions tend to stabilize the medium and suppress oscillations. In terms of
the initial data and the coefficients $ B_0 $ and $ \nu $, we establish a
criterion for maintaining the global smoothness of the solution. Namely, for
fixed $ B_0 $ and $ \nu \ge 0 $ one can precisely divide the initial data into
two classes: one leads to stabilization to the equilibrium and the other leads
to the destruction of the solution in a finite time. Next, we examine the
nature of the stabilization. We show that for small $ B_0 $ an increase in the
intensity factor first leads to a change in the oscillatory behavior of the
solution to monotonic damping, which is then again replaced by oscillatory
damping. At large values of $ B_0 $, the solution is characterized by
oscillatory damping regardless of the value of the intensity factor $ \nu $.",2111.07826v3
2021-11-20,Excitation and Damping of Slow Magnetosonic Waves in Flaring Hot Coronal Loops: Effects of Compressive Viscosity,"Slow magnetosonic waves associated with flares were observed in coronal loops
by SOHO/SUMER, SDO/AIA in various EUV bandpasses, and other instruments. The
excitation and damping of slow magnetosonic waves provides information on the
magnetic, temperature, and density structure of the loops. Recently, it was
found using 1.5D models that the thermal conduction is suppressed and
compressive viscosity is enhanced in hot (T>6 MK) flaring coronal loops. We
model the excitation and dissipation of slow magnetosonic waves in hot coronal
loops with realistic magnetic geometry, enhanced density, and temperature
(compared to background corona) guided by EUV observations using 3D MHD
visco-resistive model. The effects of compressive viscosity tensor component
along the magnetic field are included with classical and enhanced viscosity
coefficient values for the first time in 3D MHD coronal loop model. The waves
are excited by a velocity pulse at the footpoint of the loop at coronal lower
boundary. The modeling results demonstrate the excitation of the slow
magnetosonic waves and nonlinear coupling to other wave modes, such as the kink
and fast magnetosonic. We find significant leakage of the waves from the hot
coronal loops with small effect of viscous dissipation in cooler (6MK) loops,
and more significant effects of viscous dissipation in hotter (10.5MK) coronal
loops. Our results demonstrate that nonlinear 3D MHD models are required to
fully account for various wave couplings, damping, standing wave formation, and
viscous dissipation in hot flaring coronal loops. Our viscous 3D MHD code
provides a new tool for improved coronal seismology.",2111.10696v1
2021-11-27,Rate of Entropy Production in Stochastic Mechanical Systems,"Entropy production in stochastic mechanical systems is examined here with
strict bounds on its rate. Stochastic mechanical systems include pure
diffusions in Euclidean space or on Lie groups, as well as systems evolving on
phase space for which the fluctuation-dissipation theorem applies, i.e.,
return-to-equilibrium processes. Two separate ways for ensembles of such
mechanical systems forced by noise to reach equilibrium are examined here.
First, a restorative potential and damping can be applied, leading to a
classical return-to-equilibrium process wherein energy taken out by damping can
balance the energy going in from the noise. Second, the process evolves on a
compact configuration space (such as random walks on spheres, torsion angles in
chain molecules, and rotational Brownian motion) lead to long-time solutions
that are constant over the configuration space, regardless of whether or not
damping and random forcing balance. This is a kind of potential-free
equilibrium distribution resulting from topological constraints. Inertial and
noninertial (kinematic) systems are considered. These systems can consist of
unconstrained particles or more complex systems with constraints, such as
rigid-bodies or linkages. These more complicated systems evolve on Lie groups
and model phenomena such as rotational Brownian motion and nonholonomic robotic
systems. In all cases, it is shown that the rate of entropy production is
closely related to the appropriate concept of Fisher information matrix of the
probability density defined by the Fokker-Planck equation. Classical results
from information theory are then repurposed to provide computable bounds on the
rate of entropy production in stochastic mechanical systems.",2111.13930v1
2021-12-22,Strong Stabilization of a 3D Potential Flow via a Weakly Damped von Karman Plate,"The elimination of aeroelastic instability (resulting in sustained
oscillations of bridges, buildings, airfoils) is a central engineering and
design issue. Mathematically, this translates to strong asymptotic
stabilization of a 3D flow by a 2D elastic structure. The stabilization
(convergence to the stationary set) of a aerodynamic wave-plate model is
established here. A 3D potential flow on the half-space has a spatially-bounded
von Karman plate embedded in the boundary. The physical model, then, is a
Neumann wave equation with low regularity of coupling conditions. Motivated on
empirical observations, we examine if intrinsic panel damping can stabilize the
subsonic flow-plate system to a stationary point. Several partial results have
been established through partial regularization of the model. Without doing so,
classical approaches attempting to treat the given wave boundary data have
fallen short, owing to the failure of the Lopatinski condition (in the sense of
Kreiss, Sakamoto) and the associated regularity defect of the hyperbolic
Neumann mapping. Here, we operate on the panel model as in the engineering
literature with no regularization or modifications; we completely resolve the
question of stability by demonstrating that weak plate damping strongly
stabilizes system trajectories. This is accomplished by microlocalizing the
wave data (given by the plate) and observing an ""anisotropic"" a microlocal
compensation by the plate dynamics precisely where the regularity of the 3D
wave is compromsed (in the characteristic sector). Several additional stability
results for both wave and plate subsystems are established to ""push"" strong
stability of the plate onto the flow.",2112.12208v1
2021-12-28,Kinetic investigation of the planar Multipole Resonance Probe under arbitrary pressure,"Active plasma resonance spectroscopy (APRS) refers to a class of plasma
diagnostic methods that use the ability of plasma to resonate at or near the
electron plasma frequency for diagnostic purposes. The planar multipole
resonance probe (pMRP) is an optimized realization of APRS. It has a
non-invasive structure and allows simultaneous measurement of the electron
density, electron temperature, and electron-neutral collision frequency.
Previous work has investigated the pMRP through the Drude model and
collision-less kinetic model. The Drude model misses important kinetic effects
such as collision-less kinetic damping. The collision-less kinetic model is
able to capture pure kinetic effects. However, it is only applicable to
low-pressure plasma. To further study the behavior of the pMRP, we develop a
collisional kinetic model in this paper, which applies to arbitrary pressure.
In this model, the kinetic equation is coupled to the Poisson equation under
the electrostatic approximation. The real part of the general admittance is
calculated to describe the spectral response of the probe-plasma system. Both
collision-less kinetic damping and collisional damping appear in the spectrum.
This model provides a possibility to calculate the electron density, electron
temperature, and electron-neutral collision frequency from the measurements.",2112.14190v2
2021-12-28,Metadamping in inertially amplified metamaterials: Trade-off between spatial attenuation and temporal attenuation,"Metadamping is the phenomenon of either enhanced or diminished intrinsic
dissipation in a material stemming from the material's internal structural
dynamics. It has been previously shown that a locally resonant elastic
metamaterial may be designed to exhibit higher or lower dissipation compared to
a statically equivalent phononic crystal with the same amount of prescribed
damping. Here we reveal that even further dissipation, or alternatively further
reduction of loss, may be reached in an inertially amplified metamaterial that
is also statically equivalent and has the same amount of prescribed damping.
This is demonstrated by a passive configuration whereby an attenuation peak is
generated by the motion of a mass supported by an inclined lever arm. We
further show that by coupling this inertially amplified attenuation peak with
that of a local resonance attenuation peak, a trade-off between the intensity
of spatial attenuation versus temporal attenuation is realized for a range of
the inclination angles. Design for performance along this trade-off is
therefore possible by adjustment of the lever angle. These findings open the
way for highly expanding the Ashby space for stiffness-damping capacity or
stiffness-spatial attenuation capacity through design of the internal structure
of materials.",2112.14322v1
2022-01-10,Tidal erasure of stellar obliquities constrains the timing of hot Jupiter formation,"Stars with hot Jupiters sometimes have high obliquities, which are possible
relics of hot Jupiter formation. Based on the characteristics of systems with
and without high obliquities, it is suspected that obliquities are tidally
damped when the star has a thick convective envelope, as is the case for
main-sequence stars cooler than ~6100K, and the orbit is within ~8 stellar
radii. A promising theory for tidal obliquity damping is the dissipation of
inertial waves within the star's convective envelope. Here, we consider the
implications of this theory for the timing of hot Jupiter formation.
Specifically, hot stars that currently lack a convective envelope possess one
during their pre-main sequence. We find that hot Jupiters orbiting within a
critical distance of ~0.02au from a misaligned main-sequence star lacking a
thick convective envelope must have acquired their tight orbits after a few
tens of millions of years in order to have retained their obliquities
throughout the pre-main-sequence. There are 4 known systems for which this
argument applies--XO-3b, Corot-3b, WASP-14b, and WASP-121b--subject to
uncertainties surrounding inertial wave dissipation. Moreover, we conclude that
a recently-identified overabundance of near-polar hot Jupiters is unlikely
sculpted by tides, instead reflecting their primordial configuration. Finally,
hot Jupiters arriving around cool stars after a few 100s of millions of years
likely find the host star rotating too slowly for efficient obliquity damping.
We predict that the critical effective temperature separating aligned and
misaligned stars should vary with metallicity, from 6300K to 6000K as [Fe/H]
varies from -0.3 to +0.3.",2201.03653v1
2022-01-22,Examining AGN UV/optical Variability Beyond the Simple Damped Random Walk,"We present damped harmonic oscillator (DHO) light-curve modeling for a sample
of 12,714 spectroscopically confirmed quasars in the Sloan Digital Sky Survey
Stripe 82 region. DHO is a second-order continuous-time autoregressive
moving-average (CARMA) process, which can be fully described using four
independent parameters: a natural oscillation frequency ($\omega_{0}$), a
damping ratio ($\xi$), a characteristic perturbation timescale
($\tau_{\mathrm{perturb}}$), and an amplitude for the perturbing white noise
($\sigma_{\mathrm{\epsilon}}$). The asymptotic variability amplitude of a DHO
process is quantified by $\sigma_{\mathrm{DHO}}$ -- a function of $\omega_{0}$,
$\xi$, $\tau_{\mathrm{perturb}}$, and $\sigma_{\mathrm{\epsilon}}$. We find
that both $\tau_{\mathrm{perturb}}$ and $\sigma_{\mathrm{\epsilon}}$ follow
different dependencies with rest-frame wavelength ($\lambda_{\mathrm{RF}}$) on
either side of 2500 \AA, whereas $\sigma_{\mathrm{DHO}}$ follows a single
power-law relation with $\lambda_{\mathrm{RF}}$. After correcting for
wavelength dependence, $\sigma_{\mathrm{DHO}}$ exhibits anti-correlations with
both the Eddington ratio and the black hole mass, while
$\tau_{\mathrm{perturb}}$ -- with a typical value of days in the rest-frame --
shows an anti-correlation with the bolometric luminosity. Modeling AGN
variability as a DHO offers more insight into the workings of accretion disks
close to the supermassive black holes (SMBHs) at the center of AGN. The newly
discovered short-term variability (characterized by $\tau_{\mathrm{perturb}}$
and $\sigma_{\mathrm{\epsilon}}$) and its correlation with bolometric
luminosity pave the way for new algorithms that will derive fundamental
properties (e.g., Eddington ratio) of AGN using photometric data alone.",2201.08943v2
2022-02-06,Enhancing Perpendicular Magnetic Anisotropy in Garnet Ferrimagnet by Interfacing with Few-Layer WTe2,"Engineering magnetic anisotropy in a ferro- or ferrimagnetic (FM) thin film
is crucial in spintronic device. One way to modify the magnetic anisotropy is
through the surface of the FM thin film. Here, we report the emergence of a
perpendicular magnetic anisotropy (PMA) induced by interfacial interactions in
a heterostructure comprised of a garnet ferrimagnet, Y3Fe5O12 (YIG), and the
low-symmetry, high spin orbit coupling (SOC) transition metal dichalcogenide,
WTe2. At the same time, we also observed an enhancement in Gilbert damping in
the WTe2 covered YIG area. Both the magnitude of interface-induced PMA and the
Gilbert damping enhancement have no observable WTe2 thickness dependence down
to single quadruple-layer, indicating that the interfacial interaction plays a
critical role. The ability of WTe2 to enhance the PMA in FM thin film, combined
with its previously reported capability to generate out-of-plane damping like
spin torque, makes it desirable for magnetic memory applications.",2202.02834v1
2022-04-20,Ferrimagnet GdFeCo characterization for spin-orbitronics: large field-like and damping-like torques,"Spintronics is showing promising results in the search for new materials and
effects to reduce energy consumption in information technology. Among these
materials, ferrimagnets are of special interest, since they can produce large
spin currents that trigger the magnetization dynamics of adjacent layers or
even their own magnetization. Here, we present a study of the generation of
spin current by GdFeCo in a GdFeCo/Cu/NiFe trilayer where the FeCo sublattice
magnetization is dominant at room temperature. Magnetic properties such as the
saturation magnetization are deduced from magnetometry measurements while
damping constant is estimated from spin-torque ferromagnetic resonance
(ST-FMR). We show that the overall damping-like (DL) and field-like (FL)
effective fields as well as the associated spin Hall angles can be reliably
obtained by performing the dependence of ST-FMR by an added dc current. The sum
of the spin Hall angles for both the spin Hall effect (SHE) and the spin
anomalous Hall effect (SAHE) symmetries are: $\theta_{DL}^{SAHE} +
\theta_{DL}^{SHE}=-0.15 \pm 0.05$ and $\theta_{FL}^{SAHE} +
\theta_{FL}^{SHE}=0.026 \pm 0.005$. From the symmetry of ST-FMR signals we find
that $\theta_{DL}^{SHE}$ is positive and dominated by the negative
$\theta_{DL}^{SAHE}$. The present study paves the way for tuning the different
symmetries in spin conversion in highly efficient ferrimagnetic systems.",2204.09776v1
2022-04-21,Characterizing the $γ$-Ray Variability of Active Galactic Nuclei with Stochastic Process Method,"The $\gamma$-ray astronomy in time domain has been by now progressed further
as the variabilities of Active Galactic Nuclei (AGNs) on different timescales
have been reported a lot. We study the $\gamma$-ray variabilities of 23 jetted
AGNs through applying a stochastic process method to the ~12.7 yr long-term
light curve (LC) obtained by Fermi-Large Area Telescope (Fermi-LAT). In this
method, the stochastically driven damped simple harmonic oscillator (SHO) and
the damped random walk (DRW) models are used to model the long-term LCs. Our
results show that the long-term variabilities of 23 AGNs can be characterized
well by both SHO and DRW models. However, the SHO model is restricted in the
over-damped mode and the parameters are poorly constrained. The SHO power
spectral densities (PSDs) are same as the typical DRW PSD. In the plot of the
rest-frame timescale that corresponds to the broken frequency in the PSD versus
black hole mass, the intrinsic $\gamma$-ray characteristic timescales of 23
AGNs occupy almost the same space with the optical variability timescales
obtained from the accretion disk emission. This suggests a connection between
the jet and the accretion disk. Same as the optical variability of AGN
accretion disk, the $\gamma$-ray timescale is also consistent with the thermal
timescale caused by the thermal instability in the standard accretion disk of
AGN.",2204.09987v1
2022-04-29,A fast point charge interacting with the screened Vlasov-Poisson system,"We consider the long-time behavior of a fast, charged particle interacting
with an initially spatially homogeneous background plasma. The background is
modeled by the screened Vlasov-Poisson equations, whereas the interaction
potential of the point charge is assumed to be smooth. We rigorously prove the
validity of the \emph{stopping power theory} in physics, which predicts a
decrease of the velocity $V(t)$ of the point charge given by $\dot{V} \sim
-|V|^{-3} V$, a formula that goes back to Bohr (1915). Our result holds for all
initial velocities larger than a threshold value that is larger than the
velocity of all background particles and remains valid until (i) the particle
slows down to the threshold velocity, or (ii) the time is exponentially long
compared to the velocity of the point charge. The long-time behavior of this
coupled system is related to the question of Landau damping which has remained
open in this setting so far. Contrary to other results in nonlinear Landau
damping, the long-time behavior of the system is driven by the non-trivial
electric field of the plasma, and the damping only occurs in regions that the
point charge has already passed.",2205.00035v2
2022-05-06,"Discovery of a coherent, wave-like velocity pattern for the Radcliffe Wave","Recently studies discovered that part of the Gould Belt belongs to a 2.7
kpc-long {coherent, thin} wave consisting of a chain of clouds, where a damped
undulation pattern has been identified from the spatial arrangement of the
clouds. We use the proper motions of Young Stellar Objects (YSOs) anchored
inside the clouds to study the kinematic structure of the Radcliffe Wave in
terms of $v_z$, and identify a damped, wave-like pattern from the $v_z$ space,
which we call ""velocity undulation"". We propose a new formalism based on the
Ensemble Empirical Mode Decomposition (EEMD) to determine the amplitude,
period, and phase of the undulation pattern, and find that the spatial and the
velocity undulation share an almost identical spatial frequency of about 1.5
kpc, and both are damped when measured from one side to the other. Measured for
the first cycle, they exhibit a phase difference of around $2\pi/3$. The
structure is oscillating around the midplane of the Milky Way disk with an
amplitude of $\sim\,130\,\pm\,20\,\rm pc$. The vertical extent of the Radcliffe
Wave exceeds the thickness of the molecular disk, suggesting that the
undulation of the undulation signature might originate from a perturbation,
e.g. the passage of a dwarf galaxy.",2205.03218v1
2022-05-17,Resolving the HI in Damped Lyman-α systems that power star-formation,"Reservoirs of dense atomic gas (primarily hydrogen), contain approximately 90
percent of the neutral gas at a redshift of 3, and contribute to 2-3 percent of
the total baryons in the Universe. These damped Lyman-${\alpha}$ systems (so
called because they absorb Lyman-${\alpha}$ photons from within and from
background sources) have been studied for decades, but only through absorption
lines present in the spectra of background quasars and gamma-ray bursts. Such
pencil beams do not constrain the physical extent of the systems. Here, we
report integral-field spectroscopy of a bright, gravitationally lensed galaxy
at a redshift of 2.7 with two foreground damped Lyman-${\alpha}$ systems. These
systems are $>$ 238 $kpc^2$ in extent, with column densities of neutral
hydrogen varying by more than an order of magnitude on $<$ 3 kpc-scales. The
mean column densities are $10^{20.46}$ - $10^{20.84} cm^{-2}$ and the total
masses are $> 5.5 \times 10^{8}$ - $1.4 \times 10^{9} M_{\odot}$, showing that
they contain the necessary fuel for the next generation of star formation,
consistent with relatively massive, low-luminosity primeval galaxies at
redshifts $>$ 2.",2205.08554v1
2022-05-21,Accuracy of one-dimensional approximation in neutron star quasi-normal modes,"Since the eigenfrequency of gravitational waves from cold neutron stars
becomes a complex number, where the real and imaginary parts respectively
correspond to an oscillation frequency and damping rate, one has to somehow
solve the eigenvalue problem concerning the eigenvalue in two-dimensional
parameter space. To avoid this bother, one sometimes adopts an approximation,
where the eigenvalue is in one-dimensional parameter space. In this study,
first, we show the accuracy of the zero-damping approximation, which is one of
the one-dimensional approximations, for the fundamental and 1st pressure modes.
But, this approximation is not applicable to the spacetime mode, because the
damping rate of the spacetime mode is generally comparable to the oscillation
frequency. Nevertheless, we find the empirical relation for the ratio of the
imaginary part to the real part of the eigenfrequency, which is expressed as a
function of the steller compactness almost independently of the adopted
equations of state for neutron star matter. Adopting this empirical relation,
one can express the eigenfrequency in terms of just the real part, i.e., the
problem to solve becomes an eigenvalue problem with a one-dimensional
eigenvalue. Then, we find that the frequencies are estimated with good accuracy
even with such approximations even for the 1st spacetime mode.",2205.10523v1
2022-06-02,Proximity of exoplanets to first-order mean-motion resonances,"Planetary formation theories and, more specifically, migration models predict
that planets can be captured in mean-motion resonances (MMRs) during the disc
phase. The distribution of period ratios between adjacent planets shows an
accumulation in the vicinity of the resonance, which is not centred on the
nominal resonance but instead presents an offset slightly exterior to it. Here
we extend on previous works by thoroughly exploring the effect of different
disc and planet parameters on the resonance offset during the disc migration
phase. The dynamical study is carried out for several first-order MMRs and for
both low-mass Earth-like planets undergoing type-I migration and giant planets
evolving under type-II migration. We find that the offset varies with time
during the migration of the two-planet system along the apsidal corotation
resonance family. The departure from the nominal resonance increases for higher
planetary masses and stronger eccentricity damping. In the Earth to super-Earth
regime, we find offset values in agreement with the observations when using a
sophisticated modelling for the planet-disc interactions, where the damping
timescale depends on the eccentricity. This dependence causes a feedback which
induces an increase of the resonance offsets. Regarding giant planets, the
offsets of detected planet pairs are well reproduced with a classical
$K$-factor prescription for the planet-disc interactions when the eccentricity
damping rate remains low to moderate. In both regimes, eccentricities are in
agreement with the observations too. As a result, planet-disc interactions
provide a generic channel to generate the offsets found in the observations.",2206.00943v1
2022-06-03,Dynamical Instability in Multi-Orbiter Systems with Gas Friction,"Closely-packed multi-planet systems are known to experience dynamical
instability if the spacings between the planets are too small. Such instability
can be tempered by the frictional forces acting on the planets from gaseous
discs. A similar situation applies to stellar-mass black holes embedded in AGN
discs around supermassive black holes. In this paper, we use $N$-body
integrations to evaluate how the frictional damping of orbital eccentricity
affects the growth of dynamical instability for a wide range of planetary
spacing and planet-to-star mass ratios. We find that the stability of a system
depends on the damping timescale $\tau$ relative to the zero-friction
instability growth timescale $t_{\rm inst}$. In a two-planet system, the
frictional damping can stabilise the dynamical evolution if $t_{\rm
inst}\gtrsim\tau$. With three planets, $t_{\rm inst} \gtrsim 10\tau - 100\tau$
is needed for stabilisation. When the separations between the planetary orbits
are sufficiently small, $t_{\rm inst}$ can be less than the synodic period
between the planets, which makes frictional stabilisation unlikely to occur. As
the orbital spacing increases, the instability timescale tends to grow
exponentially on average, but it can vary by a few orders of magnitude
depending on the initial orbital phases of the planets. In general, the stable
region (at large orbital spacings) and unstable region (at small orbital
spacings) are separated by a transition zone, in which the (in)stability of the
system is not guaranteed. We also devise a linear map to analyse the dynamical
instability of the ""planet + test-mass"" system, and we find qualitatively
similar results to the $N$-body simulations.",2206.01755v1
2022-08-15,Nonperturbative approach to interfacial spin-orbit torques induced by Rashba effect,"Current-induced spin-orbit torque (SOT) in normal metal/ferromagnet (NM/FM)
bilayers bears great promise for technological applications, but the
microscopic origin of purely interfacial SOTs in ultra-thin systems is not yet
fully understood. Here, we show that a linear response theory with a
nonperturbative treatment of spin-dependent interactions and impurity
scattering potential predicts damping-like SOTs that are strictly absent in
perturbative approaches. The technique is applied to a two-dimensional
Rashba-coupled ferromagnet (the paradigmatic model of a NM/FM interface), where
higher-order scattering processes encoding skew scattering from nonmagnetic
impurities allow for current-induced spin polarization with nonzero components
along all spatial directions. This is in stark contrast to previous results of
perturbative methods (neglecting skew scattering), which predict a coplanar
spin-polarization locked perpendicular to the charge current as a result of
conventional Rashba-Edelstein effect. Furthermore, the angular dependence of
ensuing SOTs and their dependence upon the scattering potential strength is
analysed numerically. Simple analytic expressions for the
spin-density--charge-current response function, and related SOT efficiencies,
are obtained in the weak scattering limit. We find that the extrinsic
damping-like torques driven by impurity scattering reaches efficiencies of up
to 7% of the field-like (Rashba-Edelstein) torque. Our microscopic theory shows
that bulk phenomena, such as the spin Hall effect, are not a necessity in the
generation of the damping-like SOTs of the type observed in experiments on
ultra-thin systems.",2208.07296v1
2022-08-22,Plasma heating and nanoflare caused by slow-mode wave in a coronal loop,"We present a detailed analysis of a reflecting intensity perturbation in a
large coronal loop that appeared as sloshing oscillation and lasted for at
least one and a half periods. The perturbation is initiated by a microflare at
one footpoint of the loop, propagates along the loop and is eventually
reflected at the remote footpoint where significant brightenings are observed
in all the AIA extreme-ultraviolet (EUV) channels. This unique observation
provides us with the opportunity to better understand not only the thermal
properties and damping mechanisms of the sloshing oscillation, but also the
energy transfer at the remote footpoint. Based on differential emission
measures (DEM) analysis and the technique of coronal seismology, we find that
1) the calculated local sound speed is consistent with the observed propagation
speed of the perturbation during the oscillation, which is suggestive of a slow
magnetoacoustic wave; 2) thermal conduction is the major damping mechanism of
the wave but additional damping mechanism such as anomalous enhancement of
compressive viscosity or wave leakage is also required to account for the rapid
decay of the observed waves; 3) the wave produced a nanoflare at the remote
footpoint, with a peak thermal energy of $\thicksim10^{24}-10^{25}$ erg. This
work provides a consistent picture of the magnetoacoustic wave propagation and
reflection in a coronal loop, and reports the first solid evidence of a
wave-induced nanoflare. The results reveal new clues for further simulation
studies and may help solving the coronal heating problem.",2208.10029v1
2022-09-07,AlH lines in the blue spectrum of Proxima Centauri,"The recently-computed ExoMol line lists for isotopologues of AlH are used to
analyse the blue spectrum (4000-4500 {\AA}) of Proxima Cen (M5.5 V). Comparison
of the observed and computed spectra enables the identification of a large
number of 27AlH lines of the A1{\Pi} - X1{\Sigma}+ band system: the spectral
range covering 1-0, 0-0 and 1-1 bands is dominated by clearly resolved AlH
lines. We reveal the diffuse nature of transitions close to the dissociation
limit which appears in the form of increasingly wider(up to 5 {\AA}) and
shallower (up to the continuum confusion limit) AlH line profiles. The
predicted wavelengths of AlH diffuse lines are systematically displaced. The
effect broadening by pre-dissociation states on the line profiles is included
by increasing the radiative damping rate by up to 5 orders of magnitude. We
determine empirical values of damping rates for a number of the clean 0-0
Q-branch transitions by comparing the observed and synthetic stellar spectra.
We find excellent agreement between our damping rates and lifetimes available
in the literature. A comparison of 27Al1H ExoMol and REALH spectra shows that
the observed spectrum is better described by the ExoMol line list. A search for
26Al1H lines in the Proxima Cen spectrum does not reveal any notable features;
giving an upper limit of 27Al1H/26Al1H {>} 100.",2209.03037v2
2022-09-19,Semi-implicit Integration and Data-Driven Model Order Reduction in Structural Dynamics with Hysteresis,"Structural damping is known to be approximately rate-independent in many
cases. Popular models for rate-independent dissipation are hysteresis models;
and a highly popular hysteresis model is the Bouc-Wen model. If such hysteretic
dissipation is incorporated in a refined finite element model, then the
mathematical model includes the usual structural dynamics equations along with
nonlinear nonsmooth ordinary differential equations for a large number of
internal hysteretic states at Gauss points, to be used within the virtual work
calculation for dissipation. For such systems, numerical integration becomes
difficult due to both the distributed non-analytic nonlinearity of hysteresis
as well as the very high natural frequencies in the finite element model. Here
we offer two contributions. First, we present a simple semi-implicit
integration approach where the structural part is handled implicitly based on
the work of Pich\'e, and where the hysteretic part is handled explicitly. A
cantilever beam example is solved in detail using high mesh refinement.
Convergence is good for lower damping and a smoother hysteresis loop. For a
less smooth hysteresis loop and/or higher damping, convergence is observed to
be roughly linear on average. Encouragingly, the time step needed for stability
is much larger than the time period of the highest natural frequency of the
structural model. Subsequently, data from several simulations conducted using
the above semi-implicit method are used to construct reduced order models of
the system, where the structural dynamics is projected onto a small number of
modes and the number of hysteretic states is reduced significantly as well.
Convergence studies of error against the number of retained hysteretic states
show very good results.",2209.08765v2
2022-09-21,Performance enhancement of a spin-wave-based reservoir computing system utilizing different physical conditions,"The authors have numerically studied how to enhance reservoir computing
performance by thoroughly extracting their spin-wave device potential for
higher-dimensional information generation. The reservoir device has a 1-input
exciter and 120-output detectors on the top of a continuous magnetic garnet
film for spin-wave transmission. For various nonlinear and fading-memory
dynamic phenomena distributing in the film space, small in-plane magnetic
fields were used to prepare stripe domain structures and various damping
constants at the film sides and bottom were explored. The ferromagnetic
resonant frequency and relaxation time of spin precession clearly characterized
the change in spin dynamics with the magnetic field and damping constant. The
common input signal for reservoir computing was a 1 GHz cosine wave with random
6-valued amplitude modulation. A basic 120-dimensional reservoir output vector
was obtained from time-series signals at the 120 output detectors under each of
the three magnetic field conditions. Then, 240- and 360-dimensional reservoir
output vectors were also constructed by concatenating two and three basic ones,
respectively. In nonlinear autoregressive moving average (NARMA) prediction
tasks, the computational performance was enhanced as the dimension of the
reservoir output vector becomes higher and a significantly low prediction error
was achieved for the 10th-order NARMA using the 360-dimensional vector and
optimum damping constant. The results are clear evidence that the collection of
diverse output signals efficiently increases the dimensionality effective for
reservoir computing, i.e., reservoir-state richness. This paper demonstrates
that performance enhancement through various configuration settings is a
practical approach for on-chip reservoir computing devices with small numbers
of real output nodes.",2209.10123v1
2022-10-02,Reduction in turbulence-induced non-linear dynamic vibration using tuned liquid damper (TLD),"In the present research work, an attempt is made to develop a coupled
non-linear turbulence-structure-damper model in a finite volume-finite
difference (FV-FD) framework. Tuned liquid damper (TLD) is used as the
additional damping system along with inherent structural damping. Real-time
simulation of flow-excited bridge box girder or chimney section and the
vibration reduction using TLD can be performed using the developed model. The
turbulent flow field around a structure is modeled using an OpenFOAM transient
PISO solver, and the time-varying drag force is calculated. This force perturbs
the structure, causing the sloshing phenomena of the attached TLD, modeled
using shallow depth approximation, damping the flow-induced vibration of the
structure. The structural motion with and without the attached TLD is modeled
involving the FD-based Newmark-Beta method using in-house MATLAB codes. The TLD
is tuned with the vortex-shedding frequency of the low-Reynolds number flows,
and it is found to be reducing the structural excitation significantly. On the
other hand, the high-Reynolds number turbulent flow exhibits a broadband
excitation, for which by tuning the TLD with few frequencies obtained through
investigations, a good reduction in vibration is observed.",2210.00428v3
2022-10-17,Interpretations of the cosmic ray secondary-to-primary ratios measured by DAMPE,"Precise measurements of the boron-to-carbon and boron-to-oxygen ratios by
DAMPE show clear hardenings around $100$ GeV/n, which provide important
implications on the production, propagation, and interaction of Galactic cosmic
rays. In this work we investigate a number of models proposed in literature in
light of the DAMPE findings. These models can roughly be classified into two
classes, driven by propagation effects or by source ones. Among these models
discussed, we find that the re-acceleration of cosmic rays, during their
propagation, by random magnetohydrodynamic waves may not reproduce sufficient
hardenings of B/C and B/O, and an additional spectral break of the diffusion
coefficient is required. The other models can properly explain the hardenings
of the ratios. However, depending on simplifications assumed, the models differ
in their quality in reproducing the data in a wide energy range. The models
with significant re-acceleration effect will under-predict low-energy
antiprotons but over-predict low-energy positrons, and the models with
secondary production at sources over-predict high-energy antiprotons. For all
models high-energy positron excess exists.",2210.09205v3
2022-10-19,Energy Dissipation in Synchronous Binary Asteroids,"Synchronous binary asteroids can experience libration about their
tidally-locked equilibrium, which will result in energy dissipation. This is an
important topic to the Asteroid Impact and Deflection Assessment, where
excitation caused by the DART kinetic impact in the Didymos binary asteroid
system may be reduced through dissipation before Hera arrives to survey the
effects of the impact. We develop a numeric model for energy dissipation in
binary asteroids to explore how different system configurations affect the rate
of energy dissipation. We find tumbling within the synchronous state eliminates
a systematic trend in libration damping on short timescales (several years),
but not over long times (hundreds of years) depending on the material
conditions. Furthermore, damping of libration, eccentricity, and fluctuations
in the semimajor axis are primarily dependent on the stiffness of the
secondary, whereas the semimajor axis secular expansion rate is dictated by the
stiffness of the primary, as expected. Systems experiencing stable planar
libration in the secondary can see a noticeable reduction in libration
amplitude after only a few years depending on the stiffness of the secondary,
and thus dissipation should be considered during Hera's survey of Didymos. For
a very dissipative secondary undergoing stable libration, Hera may be able to
calculate the rate of libration damping in Dimorphos and therefore constrain
its tidal parameters.",2210.10877v1
2022-11-14,Heavily Damped Precessional Switching with Very Low Write-error Rate in Elliptical-cylinder Magnetic Tunnel Junction,"Voltage-induced dynamic switching in magnetic tunnel junctions (MTJs) is a
writing technique for voltage-controlled magnetoresistive random access memory
(VCMRAM), which is expected to be an ultimate non-volatile memory with
ultra-low power consumption. In conventional dynamic switching, the width of
sub-nanosecond write voltage pulses must be precisely controlled to achieve a
sufficiently low write-error rate (WER). This very narrow tolerance of pulse
width is the biggest technical difficulty in developing VCMRAM. Heavily damped
precessional switching is a writing scheme for VCMRAM with a substantially high
tolerance of pulse width although the minimum WER has been much higher than
that of conventional dynamic switching with an optimum pulse width. In this
study, we theoretically investigate the effect of MTJ shape and the direction
of the applied magnetic field on the WER of heavily damped precessional
switching. The results show that the WER in elliptical-cylinder MTJ can be
several orders of magnitude smaller than that in usual circular-cylinder MTJ
when the external magnetic field is applied parallel to the minor axis of the
ellipse. The reduction in WER is due to the fact that the demagnetization field
narrows the component of the magnetization distribution perpendicular to the
plane direction immediately before the voltage is applied.",2211.07148v1
2022-11-19,Regularity to Timoshenko's System with Thermoelasticity of Type III with Fractional Damping,"The article, presents the study of the regularity of two thermoelastic beam
systems defined by the Timoshenko beam model coupled with the heat conduction
of Green-Naghdiy theory of type III, both mathematical models are
differentiated by their coupling terms that arise as a consequence of the
constitutive laws initially considered. The systems presented in this work have
3 fractional dampings: $\mu_1(-\Delta)^\tau \phi_t$, $\mu_2(-\Delta)^\sigma
\psi_t$ and $K(-\Delta)^\xi \theta_t$, where $\phi,\psi$ and $\theta$ are
transverse displacement, rotation angle and empirical temperature of the bean
respectively and the parameters $(\tau,\sigma,\xi)\in [0,1]^3$. It is noted
that for values 0 and 1 of the parameter $\tau$, the so-called frictional or
viscous damping will be faced, respectively. The main contribution of this
article is to show that the corresponding semigroup
$S_i(t)=e^{\mathcal{B}_it}$, with $i=1,2$, is of Gevrey class
$s>\frac{r+1}{2r}$ for $r=\min \{\tau,\sigma,\xi\}$ for all
  $(\tau,\sigma,\xi )\in R_{CG}:= (0, 1)^3$. It is also showed that
$S_1(t)=e^{\mathcal{B}_1t}$ is analytic in the region $R_{A_1}:=\{(\tau,\sigma,
\xi )\in [\frac{1}{2},1]^3\}$ and $S_2(t)=e^{\mathcal{B}_2t}$ is analytic in
the region $R_{A_2}:=\{(\tau,\sigma, \xi )\in [\frac{1}{2},1]^3/ \tau=\xi\}$.",2211.10816v2
2022-11-28,Exciting the TTV Phases of Resonant Sub-Neptunes,"There are excesses of sub-Neptunes just wide of period commensurabilities
like the 3:2 and 2:1, and corresponding deficits narrow of them. Any theory
that explains this period ratio structure must also explain the strong transit
timing variations (TTVs) observed near resonance. Besides an amplitude and a
period, a sinusoidal TTV has a phase. Often overlooked, TTV phases are
effectively integration constants, encoding information about initial
conditions or the environment. Many TTVs near resonance exhibit non-zero
phases. This observation is surprising because dissipative processes that
capture planets into resonance also damp TTV phases to zero. We show how both
the period ratio structure and the non-zero TTV phases can be reproduced if
pairs of sub-Neptunes capture into resonance in a gas disc while accompanied by
a third eccentric non-resonant body. Convergent migration and eccentricity
damping by the disc drives pairs to orbital period ratios wide of
commensurability; then, after the disc clears, secular forcing by the third
body phase-shifts the TTVs. The scenario predicts that resonant planets are
apsidally aligned and possess eccentricities up to an order of magnitude larger
than previously thought.",2211.15701v2
2022-12-04,An Unsupervised Machine Learning Method for Electron--Proton Discrimination of the DAMPE Experiment,"Galactic cosmic rays are mostly made up of energetic nuclei, with less than
$1\%$ of electrons (and positrons). Precise measurement of the electron and
positron component requires a very efficient method to reject the nuclei
background, mainly protons. In this work, we develop an unsupervised machine
learning method to identify electrons and positrons from cosmic ray protons for
the Dark Matter Particle Explorer (DAMPE) experiment. Compared with the
supervised learning method used in the DAMPE experiment, this unsupervised
method relies solely on real data except for the background estimation process.
As a result, it could effectively reduce the uncertainties from simulations.
For three energy ranges of electrons and positrons, 80--128 GeV, 350--700 GeV,
and 2--5 TeV, the residual background fractions in the electron sample are
found to be about (0.45 $\pm$ 0.02)$\%$, (0.52 $\pm$ 0.04)$\%$, and (10.55
$\pm$ 1.80)$\%$, and the background rejection power is about (6.21 $\pm$ 0.03)
$\times$ $10^4$, (9.03 $\pm$ 0.05) $\times$ $10^4$, and (3.06 $\pm$ 0.32)
$\times$ $10^4$, respectively. This method gives a higher background rejection
power in all energy ranges than the traditional morphological parameterization
method and reaches comparable background rejection performance compared with
supervised machine learning~methods.",2212.01843v1
2022-12-05,Stability of Cnoidal Waves for the Damped Nonlinear Schrödinger Equation,"We consider the cubic nonlinear Schr\""odinger (NLS) equation with a linear
damping on the one dimensional torus and we investigate the stability of some
solitary wave profiles within the dissipative dynamics. The undamped cubic NLS
equation is well known to admit a family of periodic waves given by Jacobi
elliptic functions of cnoidal type. We show that the family of cnoidal waves is
orbitally stable. More precisely, by considering a sufficiently small
perturbation of a given cnoidal wave at initial time, the evolution will always
remain close (up to symmetries of the equation) to the cnoidal wave whose mass
is modulated according to the dissipative dynamics. This result extends the
concept of orbital stability to this non-Hamiltonian evolution. Since cnoidal
waves are not exact solutions to the damped NLS, the perturbation is forced
away from the family of solitary wave profiles. In order to control this
secular growth of the error, we find a first order approximation of the
solitary wave that takes into account the dissipative term. Then we use a
suitable, exponentially decreasing Lyapunov functional that controls the
$H^1$-norm of the perturbation around the approximated solitons.",2212.02195v2
2022-12-08,Strong photon-magnon coupling using a lithographically defined organic ferrimagnet,"We demonstrate a hybrid quantum system composed of superconducting resonator
photons and magnons hosted by the organic-based ferrimagnet vanadium
tetracyanoethylene (V[TCNE]$_x$). Our work is motivated by the challenge of
scalably integrating an arbitrarily-shaped, low-damping magnetic system with
planar superconducting circuits, thus enabling a host of quantum magnonic
circuit designs that were previously inaccessible. For example, by leveraging
the inherent properties of magnons, one can enable nonreciprocal
magnon-mediated quantum devices that use magnon propagation rather than
electrical current. We take advantage of the properties of V[TCNE]$_x$, which
has ultra-low intrinsic damping, can be grown at low processing temperatures on
arbitrary substrates, and can be patterned via electron beam lithography. We
demonstrate the scalable, lithographically integrated fabrication of hybrid
quantum magnonic devices consisting of a thin-film superconducting resonator
coupled to a low-damping, thin-film V[TCNE]$_x$ microstructure. Our devices
operate in the strong coupling regime, with a cooperativity as high as 1181(44)
at T$\sim$0.4 K, suitable for scalable quantum circuit integration. This work
paves the way for the exploration of high-cooperativity hybrid magnonic quantum
devices in which magnonic circuits can be designed and fabricated as easily as
electrical wires.",2212.04423v1
2022-12-28,Scattering of the UHECR at small pitch angle by damped plasma waves,"In spite a lot of theoretical and experimental effort that has been achieved
in ultra-high energy cosmic ray (UHECR) scattering research in last few
decades, some questions remain unanswered, or partially answered. Two of them,
that will be in the focus of this paper are: possible source of UHECRs and the
acceleration mechanism of cosmic rays beyond PeV energies. Small pitch-angle
scattering of UHECRs and possible confinement has been investigated using
quasilinear theory in order to analytically calculate pitch-angle Fokker-Planck
coefficient. CR particles resonantly interact with oblique low frequency damped
waves. We show that the resonance function is broadened due to damping effects
and this result is compared with the nonlinear broadening. Unlike the case of
purely parallel (or antiparallel) propagating waves in slab turbulence, the
presence of the compressive magnetic field component of oblique fast-mode waves
allows the cosmic ray particles to resonantly interact with these waves through
the n = 0 resonance, together with gyroresonance, which strongly influence the
Hillas limit. The derived results can be used to compute the parallel mean free
path for all forms of the turbulence spectrum; it has been applied on the
transport and propagation of CRs close to ultra-high energies in the Galaxy. An
accurate understanding of particle acceleration in astrophysical sources could
help to interpret eventual transition from Galactic to extragalactic origin of
cosmic rays, if any, and the shape of the UHECR spectrum at the highest
energies.",2212.13755v1
2023-01-23,Estimation of turbulent proton and electron heating rates via Landau damping constrained by Parker Solar Probe observations,"The heating of ions and electrons due to turbulent dissipation plays a
crucial role in the thermodynamics of the solar wind and other plasma
environments. Using magnetic field and thermal plasma observations from the
first two perihelia of the Parker Solar Probe (PSP), we model the relative
heating rates as a function of radial distance, magnetic spectra, and plasma
conditions, enabling us to better characterize the thermodynamics of the inner
heliosphere. We employ the Howes et al. 2008 steady-state cascade model, which
considers the behavior of turbulent, low-frequency, wavevector-anisotropic,
critically balanced Alfv\'enic fluctuations that dissipate via Landau damping
to determine proton-to-electron heating rates $Q_p/Q_e$. We distinguish
ion-cyclotron frequency circularly polarized waves from low-frequency
turbulence and constrain the cascade model using spectra constructed from the
latter. We find that the model accurately describes the observed energy
spectrum from over 39.4 percent of the intervals from Encounters 1 and 2,
indicating the possibility for Landau damping to heat the young solar wind. The
ability of the model to describe the observed turbulent spectra increases with
the ratio of thermal-to-magnetic pressure, $\beta_p$, indicating that the model
contains the necessary physics at higher $\beta_p$. We estimate high magnitudes
for the Kolmogorov constant which is inversely proportional to the non-linear
energy cascade rate. We verify the expected strong dependency of $Q_p/Q_e$ on
$\beta_p$ and the consistency of the critical balance assumption.",2301.09713v1
2023-02-02,Leveraging symmetry for an accurate spin-orbit torques characterization in ferrimagnetic insulators,"Spin-orbit torques (SOTs) have emerged as an efficient means to electrically
control the magnetization in ferromagnetic heterostructures. Lately, an
increasing attention has been devoted to SOTs in heavy metal (HM)/magnetic
insulator (MI) bilayers owing to their tunable magnetic properties and
insulating nature. Quantitative characterization of SOTs in HM/MI
heterostructures are, thus, vital for fundamental understanding of charge-spin
interrelations and designing novel devices. However, the accurate determination
of SOTs in MIs have been limited so far due to small electrical signal outputs
and dominant spurious thermoelectric effects caused by Joule heating. Here, we
report a simple methodology based on harmonic Hall voltage detection and
macrospin simulations to accurately quantify the damping-like and field-like
SOTs, and thermoelectric contributions separately in MI-based systems.
Experiments on the archetypical Bi-doped YIG/Pt heterostructure using the
developed method yield precise values for the field-like and damping-like SOTs,
reaching -0.14 and -0.15 mT per 1.7x$10^{ 11}$ A/$m^2$, respectively. We
further reveal that current-induced Joule heating changes the spin transparency
at the interface, reducing the spin Hall magnetoresistance and damping-like
SOT, simultaneously. These results and the devised method can be beneficial for
fundamental understanding of SOTs in MI-based heterostructures and designing
new devices where accurate knowledge of SOTs is necessary.",2302.01141v2
2022-12-31,Genuine three qubit Einstein-Podolsky-Rosen steering under decoherence: Revealing hidden genuine steerability via pre-processing,"The behaviour of genuine EPR steering of three qubit states under various
environmental noises is investigated. In particular, we consider the two
possible steering scenarios in the tripartite setting: (1 -> 2), where Alice
demonstrates genuine steering to Bob-Charlie, and (2 -> 1), where Alice-Bob
together demonstrates genuine steering to Charlie. In both these scenarios, we
analyze the genuine steerability of the generalized Greenberger-Horne-Zeilinger
(gGHZ) states or the W-class states under the action of noise modeled by
amplitude damping (AD), phase flip (PF), bit flip (BF), and phase damping (PD)
channels. In each case, we consider three different interactions with the noise
depending upon the number of parties undergoing decoherence. We observed that
the tendency to demonstrate genuine steering decreases as the number of parties
undergoing decoherence increases from one to three. We have observed several
instances where the genuine steerability of the state revives after collapsing
if one keeps on increasing the damping. However, the hidden genuine
steerability of a state cannot be revealed solely from the action of noise. So,
the parties having a characterized subsystem, perform local pre-processing
operations depending upon the steering scenario and the state shared with the
dual intent of revealing hidden genuine steerability or enhancing it.",2302.02987v1
2023-02-20,Optimal energy harvesting efficiency from vortex-induced vibration of a circular cylinder under flow,"This work applies a combined approach a reduced-order model (ROM) together
with experiments and direct numerical simulations to investigate the optimal
efficiency of fluid-flow energy harvesting from transverse vortex-induced
vibration (VIV) of a circular cylinder. High resolution efficiency maps were
predicted over wide ranges of flow reduced velocities and structural damping
ratios, and the maximum efficiency and optimal settings of damping ratio and
reduced velocity were then examined for different mass ratios and Reynolds
numbers. Efficiencies predicted by the ROM were also validated against either
experiments or direct simulations. The present work indicates that: (i) the
maximum efficiency is controlled by both the incoming reduced velocity and the
product of mass ratio and structural damping ratio, which is similar to the
maximum amplitude of VIV; (ii) the maximum efficiency at a relatively high
Reynolds number ($Re \approx 6 \times 10^3$) in subcritical regime is higher
than that of a low Reynolds number ($Re = 150$) in laminar regime; (iii) the
energy harvesting efficiency from VIV of a circular cylinder with a low mass
ratio is more robust than that with a high mass ratio. This finding suggests
that the VIV harvester performs better in water than in air.",2302.09975v1
2023-04-12,Liouvillian exceptional points in continuous variable system,"The Liouvillian exceptional points for a quantum Markovian master equation of
an oscillator in a generic environment are obtained. They occur at the points
when the modified frequency of the oscillator vanishes, whereby the eigenvalues
of the Liouvillian become real. In a generic system there are two parameters
that modify the oscillator's natural frequency. One of the parameters can be
the damping rate. The exceptional point then corresponds to critical damping of
the oscillator. This situation is illustrated by the Caldeira--Leggett (CL)
equation and the Markovian limit of the Hu--Paz--Zhang (HPZ) equation. The
other parameter changes the oscillator's effective mass whereby the exceptional
point is reached in the limit of extremely heavy oscillator. This situation is
illustrated by a modified form of the Kossakowski--Lindblad (KL) equation. The
eigenfunctions coalesce at the exceptional points and break into subspaces
labelled by a natural number $N$. In each of the $N$-subspace, there is a
$(N+1)$-fold degeneracy and the Liouvillian has a Jordan block structure of
order-$(N+1)$. We obtain the explicit form of the generalized eigenvectors for
a few Liouvillians. Because of the degeneracies, there is a freedom of choice
in the generalized eigenfunctions. This freedom manifests itself as an
invariance in the Jordan block structure under a similarity transformation
whose form is obtained. We compare the relaxation of the first excited state of
an oscillator in the underdamped region, critically damped region which
corresponds to the exceptional point, and overdamped region using the
generalized eigenvectors of the CL equation.",2304.05792v2
2023-04-13,Network-Reconfiguration-Aware Power Oscillation Damping Controller for Newly Commissioned Converter-Interfaced Power Plants,"In recent years, transmission system operators have started requesting
converter-interfaced generators (CIGs) to participate in grid services such as
power oscillation damping (POD). As power systems are prone to topology changes
because of connection and disconnection of generators and electrical lines, one
of the most important requirements in the POD controller design is to account
for these changes and to deal with them by using either adaptive or robust
approaches. The robust approach is usually preferred by system operators
because of the fixed structure of the controller. In this paper, a procedure to
design POD controllers for CIG-based power plants that takes into consideration
all possible network configurations is presented. This procedure is based on
frequency-response techniques, so it is suitable for the commissioning in newly
installed power plants, even in those cases when a detailed small-signal model
of the system is not available. This procedure can be used to damp critical
system modes by using active power, reactive power, or both power components
simultaneously. The proposed procedure is applied to the design of the POD
controller for a CIG-based power plant connected to the IEEE 39 Bus system.
Simulations performed in Matlab and SimPowerSystems are used to validate the
proposed design procedure.",2304.06555v1
2023-06-13,Particle-resolved study of the onset of turbulence,"The transition from laminar to turbulent flow is an immensely important topic
that is still being studied. Here we show that complex plasmas, i.e.,
microparticles immersed in a low temperature plasma, make it possible to study
the particle-resolved onset of turbulence under the influence of damping, a
feat not possible with conventional systems. We performed three-dimensional
(3D) molecular dynamics (MD) simulations of complex plasmas flowing past an
obstacle and observed 3D turbulence in the wake and fore-wake region of this
obstacle. We found that we could reliably trigger the onset of turbulence by
changing key parameters such as the flow speed and particle charge, which can
be controlled in experiments, and show that the transition to turbulence
follows the conventional pathway involving the intermittent emergence of
turbulent puffs. The power spectra for fully developed turbulence in our
simulations followed the -5/3 power law of Kolmogorovian turbulence in both
time and space. We demonstrate that turbulence in simulations with damping
occurs after the formation of shock fronts, such as bow shocks and Mach cones.
By reducing the strength of damping in the simulations, we could trigger a
transition to turbulence in an undamped system. This work opens the pathway to
detailed experimental and simulation studies of the onset of turbulence on the
level of the carriers of the turbulent interactions, i.e., the microparticles.",2306.07711v1
2023-07-10,Vibroacoustic simulations of acoustic damping materials using a fictitious domain approach,"The numerical investigation of acoustic damping materials, such as foams,
constitutes a valuable enhancement to experimental testing. Typically, such
materials are modeled in a homogenized way in order to reduce the computational
effort and to circumvent the need for a computational mesh that resolves the
complex micro-structure. However, to gain detailed insight into the acoustic
behavior, e.g., the transmittance of noise, such fully resolved models are
mandatory. The meshing process can still be avoided by using a ficticious
domain approach. We propose the finite cell method, which combines the
ficticious domain approach with high-order finite elements and resolves the
complex geometry using special quadrature rules. In order to take into account
the fluid-filled pores of a typical damping material, a coupled vibroacoustic
problem needs to be solved. To this end, we construct two separate finite cell
discretizations and prescribe coupling conditions at the interface in the usual
manner. The only difference to a classical boundary fitted approach to
vibroacoustics is that the fluid-solid interface is immersed into the
respective discretization and does not correspond to the element boundaries.
The proposed enhancement of the finite cell method for vibroacoustics is
verified based on a comparison with commercial software and used within an
exemplary application.",2307.04624v1
2023-07-12,A coupled rate-dependent/rate-independent system for adhesive contact in Kirchhoff-Love plates,"We perform a dimension reduction analysis for a coupled
rate-dependent/rate-independent adhesive-contact model in the setting of
visco-elastodynamic plates. We work with a weak solvability notion inspired by
the theory of (purely) rate-independent processes, and accordingly term the
related solutions `Semistable Energetic'. For Semistable Energetic solutions,
the momentum balance holds in a variational sense, whereas the flow rule for
the adhesion parameter is replaced by a semi-stability condition coupled with
an energy-dissipation inequality. Prior to addressing the dimension reduction
analysis, we show that Semistable Energetic solutions to the three-dimensional
damped adhesive contact model converge, as the viscosity term tends to zero, to
three-dimensional Semistable Energetic solutions for the undamped corresponding
system. We then perform a dimension reduction analysis, both in the case of a
vanishing viscosity tensor (leading, in the limit, to an undamped model), and
in the complementary setting in which the damping is assumed to go to infinity
as the thickness of the plate tends to zero. In both regimes, the presence of
adhesive contact yields a nontrivial coupling of the in-plane and out-of-plane
contributions. In the undamped scenario we obtain in the limit an
energy-dissipation inequality and a semistability condition. In the damped
case, instead, we achieve convergence to an enhanced notion of solution,
fulfilling an energy-dissipation balance.",2307.06327v1
2023-08-16,Large time asymptotics for partially dissipative hyperbolic systems without Fourier analysis: application to the nonlinearly damped p-system,"A new framework to obtain time-decay estimates for partially dissipative
hyperbolic systems set on the real line is developed. Under the classical
Shizuta-Kawashima (SK) stability condition, equivalent to the Kalman rank
condition in control theory, the solutions of these systems decay exponentially
in time for high frequencies and polynomially for low ones. This allows to
derive a sharp description of the space-time decay of solutions for large time.
However, such analysis relies heavily on the use of the Fourier transform that
we avoid here, developing the ""physical space version"" of the hyperbolic
hypocoercivity approach introduced by Beauchard and Zuazua, to prove new
asymptotic results in the linear and nonlinear settings. The new physical space
version of the hyperbolic hypocoercivity approach allows to recover the natural
heat-like time-decay of solutions under sharp rank conditions, without
employing Fourier analysis or $L^1$ assumptions on the initial data. Taking
advantage of this Fourier-free framework, we establish new enhanced time-decay
estimates for initial data belonging to weighted Sobolev spaces. These results
are then applied to the nonlinear compressible Euler equations with linear
damping. We also prove the logarithmic stability of the nonlinearly damped
$p$-system.",2308.08280v2
2023-08-28,The Effects of Non-Equilibrium Velocity Distributions on Alfvén Ion-Cyclotron Waves in the Solar Wind,"In this work, we investigate how the complex structure found in solar wind
proton velocity distribution functions (VDFs), rather than the commonly assumed
two-component bi-Maxwellian structure, affects the onset and evolution of
parallel-propagating microinstabilities. We use the Arbitrary Linear Plasma
Solver (ALPS), a numerical dispersion solver, to find the real frequencies and
growth/damping rates of the Alfv\'en modes calculated for proton VDFs extracted
from Wind spacecraft observations of the solar wind. We compare this wave
behavior to that obtained by applying the same procedure to core-and-beam
bi-Maxwellian fits of the Wind proton VDFs. We find several significant
differences in the plasma waves obtained for the extracted data and
bi-Maxwellian fits, including a strong dependence of the growth/damping rate on
the shape of the VDF. By application of the quasilinear diffusion operator to
these VDFs, we pinpoint resonantly interacting regions in velocity space where
differences in VDF structure significantly affect the wave growth and damping
rates. This demonstration of the sensitive dependence of Alfv\'en mode behavior
on VDF structure may explain why the Alfv\'en ion-cyclotron instability
thresholds predicted by linear theory for bi-Maxwellian models of solar wind
proton background VDFs do not entirely constrain spacecraft observations of
solar wind proton VDFs, such as those made by the Wind spacecraft.",2308.14944v1
2023-08-31,Search for the gamma-ray spectral lines with the DAMPE and the Fermi-LAT observations,"Weakly interacting massive particles, as a major candidate of dark matter
(DM), may directly annihilate or decay into high-energy photons, producing
monochromatic spectral lines in the gamma-ray band. These spectral lines, if
detected, are smoking-gun signatures for the existence of new physics. Using
the 5 years of DAMPE and 13 years of Fermi-LAT data, we search for line-like
signals in the energy range of 3 GeV to 1 TeV from the Galactic halo. Different
regions of interest are considered to accommodate different DM density
profiles. We do not find any significant line structure, and the previously
reported line-like feature at $\sim$133 GeV is also not detected in our
analysis. Adopting a local DM density of $\rho_{\rm local}=0.4\,{\rm
GeV\,cm^{-3}}$, we derive 95% confidence level constraints on the
velocity-averaged cross-section of $\langle{\sigma v}\rangle_{\gamma\gamma}
\lesssim 4 \times 10^{-28}\,{\rm cm^{3}\,s^{-1}}$ and the decay lifetime of
$\tau_{\gamma\nu} \gtrsim 5 \times 10^{29}\,{\rm s}$ at 100 GeV, achieving the
strongest constraints to date for the line energies of 6-660 GeV. The
improvement stems from the longer Fermi-LAT data set used and the inclusion of
DAMPE data in the analysis. The simultaneous use of two independent data sets
could also reduce the systematic uncertainty of the search.",2308.16762v1
2023-09-06,Strong magnon-magnon coupling in an ultralow damping all-magnetic-insulator heterostructure,"Magnetic insulators such as yttrium iron garnets (YIGs) are of paramount
importance for spin-wave or magnonic devices as their ultralow damping enables
ultralow power dissipation that is free of Joule heating, exotic magnon quantum
state, and coherent coupling to other wave excitations. Magnetic insulator
heterostructures bestow superior structural and magnetic properties and house
immense design space thanks to the strong and engineerable exchange interaction
between individual layers. To fully unleash their potential, realizing low
damping and strong exchange coupling simultaneously is critical, which often
requires high quality interface. Here, we show that such a demand is realized
in an all-insulator thulium iron garnet (TmIG)/YIG bilayer system. The ultralow
dissipation rates in both YIG and TmIG, along with their significant spin-spin
interaction at the interface, enable strong and coherent magnon-magnon coupling
with a benchmarking cooperativity value larger than the conventional
ferromagnetic metal-based heterostructures. The coupling strength can be tuned
by varying the magnetic insulator layer thickness and magnon modes, which is
consistent with analytical calculations and micromagnetic simulations. Our
results demonstrate TmIG/YIG as a novel platform for investigating hybrid
magnonic phenomena and open opportunities in magnon devices comprising
all-insulator heterostructures.",2309.03116v1
2023-09-14,A new break near 10 TeV in the energy spectrum of protons according to data from space-based instruments: astrophysical interpretation,"Recent experimental data from space-based instruments of the DAMPE and CALET
collaborations have shown that the energy spectrum of protons has a new
feature, a break in the $\sim 10$ TeV region. In this energy range, the
spectrum index of the observed particles varies from $-2.6$ to $-2.9$.
  The purpose of this work is to establish the local sources's position and age
that determine this break, the index of the proton generation spectrum in them,
as well as the astrophysical interpretation of the results obtained in the
DAMPE and CALET experiments.
  Within the framework of the model of nonclassical diffusion of cosmic rays
developed by the authors, which has break due to the propagation of particles
in a sharply inhomogeneous (fractal type) galactic medium, it is shown that
break in this energy range is formed by tevatron located at a distance of $\sim
120$ pc from the Earth. These source, whose age is $\sim 5 \cdot 10^5$ years,
generate particles with a spectrum index $\sim 2.7$.
  The power-law behavior of the proton spectrum before and after the break,
soft spectrum of particles generation in the source, first obtained in the
DAMPE and CALET experiments, should be considered as an indication of the need
to revise the standard paradigm accepted today about the sources of cosmic
rays, mechanisms of particle acceleration in them and particles propagation in
the Galaxy.",2309.07420v1
2023-11-06,Phase mixing of propagating Alfv{é}n waves in a single-fluid partially ionized solar plasma,"Phase mixing of Alfven waves is one of the most promising mechanisms for
heating of the solar atmosphere. The damping of waves in this case requires
small transversal scales, relative to the magnetic field direction. Here this
requirement is achieved by considering a transversal inhomogeneity in the
equilibrium plasma density profile. Using a single fluid approximation of a
partially ionized chromospheric plasma we study the effectiveness of the
damping of phase mixed shear Alfven waves and investigate the effect of varying
the ionization degree on the dissipation of waves. Our results show that the
dissipation length of shear Alfven waves strongly depends on the ionization
degree of the plasma, but more importantly, in a partially ionized plasma, the
damping length of shear Alfven waves is several orders of magnitude shorter
than in the case of a fully ionized plasma, providing evidence that phase
mixing could be a large contributor to heating the solar chromosphere. The
effectiveness of phase mixing is investigated for various ionization degrees,
ranging from very weakly to very strongly ionized plasmas. Our results show
that phase mixed propagating Alfven waves in a partially ionized plasma with
ionization degrees in the range 0.518 to 0.657, corresponding to heights of
1916 to 2150 km above the solar surface, can provide sufficient heating to
balance chromospheric radiative losses in the quiet Sun.",2311.02989v1
2023-11-15,Damped Proximal Augmented Lagrangian Method for weakly-Convex Problems with Convex Constraints,"We give a damped proximal augmented Lagrangian method (DPALM) for solving
problems with a weakly-convex objective and convex linear/nonlinear
constraints. Instead of taking a full stepsize, DPALM adopts a damped dual
stepsize to ensure the boundedness of dual iterates. We show that DPALM can
produce a (near) $\vareps$-KKT point within $O(\vareps^{-2})$ outer iterations
if each DPALM subproblem is solved to a proper accuracy. In addition, we
establish overall iteration complexity of DPALM when the objective is either a
regularized smooth function or in a regularized compositional form. For the
former case, DPALM achieves the complexity of
$\widetilde{\mathcal{O}}\left(\varepsilon^{-2.5} \right)$ to produce an
$\varepsilon$-KKT point by applying an accelerated proximal gradient (APG)
method to each DPALM subproblem. For the latter case, the complexity of DPALM
is $\widetilde{\mathcal{O}}\left(\varepsilon^{-3} \right)$ to produce a near
$\varepsilon$-KKT point by using an APG to solve a Moreau-envelope smoothed
version of each subproblem. Our outer iteration complexity and the overall
complexity either generalize existing best ones from unconstrained or
linear-constrained problems to convex-constrained ones, or improve over the
best-known results on solving the same-structured problems. Furthermore,
numerical experiments on linearly/quadratically constrained non-convex
quadratic programs and linear-constrained robust nonlinear least squares are
conducted to demonstrate the empirical efficiency of the proposed DPALM over
several state-of-the art methods.",2311.09065v1
2023-12-07,Nonlinear aspects of stochastic particle acceleration,"In turbulent magnetized plasmas, charged particles can be accelerated to high
energies through their interactions with the turbulent motions. As they do so,
they draw energy from the turbulence, possibly up to the point where they start
modifying the turbulent cascade. Stochastic acceleration then enters a
nonlinear regime because turbulence damping back-reacts in turn on the
acceleration process. This article develops a phenomenological model to examine
this situation in detail and to explore its consequences for the particle and
turbulent energy spectra. We determine a criterion that specifies the threshold
of nonthermal particle energy density and the characteristic momentum beyond
which back-reaction becomes effective. Once the back-reaction sets in, the
turbulence cascade becomes damped below a length scale that keeps increasing in
time. The accelerated particle momentum distribution develops a near power-law
of the form ${\rm d}n/{\rm d}p\propto p^{-s}$ with $s\sim2$ beyond the momentum
at which back-reaction first sets in. At very high energies, where the
gyroradius of accelerated particles becomes comparable to the outer scale of
the turbulence, the energy spectrum can display an even harder spectrum with
$s\sim 1.3-1.5$ over a short segment. The low-energy part of the spectrum,
below the critical momentum, is expected to be hard ($s\sim 1$ or harder), and
shaped by any residual acceleration process in the damped region of the
turbulence cascade. This characteristic broken power-law shape with $s\sim 2$
at high energies may find phenomenological applications in various high-energy
astrophysical contexts.",2312.04443v2
2023-12-12,Circularization in the damped Kepler problem,"In this paper, we revisit the damped Kepler problem within a general family
of nonlinear damping forces with magnitude $\delta \vert u\vert^{\beta}\vert
\dot u\vert^{\alpha+1}$, depending on three parameters $\delta>0,\alpha\ge 0$
and $\beta\ge 0$, and address the general question of circularization whereby
orbits tend to become more circular as they approach the sun. Our approach is
based on dynamical systems theory, using blowup and desingularization as our
main technical tools. We find that $\gamma=\alpha+2\beta-3$ is an important
quantity, with the special case $\gamma=0$ separating circularization
($-3<\gamma<0$) where the eccentricity converges to zero, i.e. $e(t)\rightarrow
0$ as $u(t)\rightarrow 0$, from cases ($\gamma>0$) where $e(t)\rightarrow 1$ as
$u(t)\rightarrow 0$, both on open sets of initial conditions. We find that
circularization for $-3<\gamma<0$ occurs due to asymptotic stability of a
zero-Hopf equilibrium point (i.e., the eigenvalues are $\pm i \omega,0$) of a
three-dimensional reduced problem (which is analytic in the blowup
coordinates). The attraction is therefore not hyperbolic and in particular not
covered by standard dynamical systems theory. Instead we use recent results on
normal forms of the zero-Hopf to locally bring the system into a form where the
stability can be addressed directly. We believe that our approach can be used
to describe unbounded solutions.",2312.07249v1
2023-12-21,Annealing reduces Si$_3$N$_4$ microwave-frequency dielectric loss in superconducting resonators,"The dielectric loss of silicon nitride (Si$_3$N$_4$) limits the performance
of microwave-frequency devices that rely on this material for sensing, signal
processing, and quantum communication. Using superconducting resonant circuits,
we measure the cryogenic loss tangent of either as-deposited or
high-temperature annealed stoichiometric Si$_3$N$_4$ as a function of drive
strength and temperature. The internal loss behavior of the electrical
resonators is largely consistent with the standard tunneling model of two-level
systems (TLS), including damping caused by resonant energy exchange with TLS
and by the relaxation of non-resonant TLS. We further supplement the TLS model
with a self-heating effect to explain an increase in the loss observed in
as-deposited films at large drive powers. Critically, we demonstrate that
annealing remedies this anomalous power-induced loss, reduces the
relaxation-type damping by more than two orders of magnitude, and reduces the
resonant-type damping by a factor of three. Employing infrared absorption
spectroscopy, we find that annealing reduces the concentration of hydrogen in
the Si$_3$N$_4$, suggesting that hydrogen impurities cause substantial
dissipation.",2312.13504v1
2023-12-31,Molecular Hybridization Induced Antidamping and Sizable Enhanced Spin-to-Charge Conversion in Co20Fe60B20/$β$-W/C60 Heterostructures,"Development of power efficient spintronics devices has been the compelling
need in the post-CMOS technology era. The effective tunability of
spin-orbit-coupling (SOC) in bulk and at the interfaces of hybrid materials
stacking is a prerequisite for scaling down the dimension and power consumption
of these devices. In this work, we demonstrate the strong chemisorption of C60
molecules when grown on the high SOC $\beta$-W layer. The parent CFB/$\beta$-W
bilayer exhibits large spin-to-charge interconversion efficiency, which can be
ascribed to the interfacial SOC observed at the Ferromagnet/Heavy metal
interface. Further, the adsorption of C60 molecules on $\beta$-W reduces the
effective Gilbert damping by $\sim$15% in the CFB/$\beta$-W/C60
heterostructures. The anti-damping is accompanied by a gigantic $\sim$115%
enhancement in the spin-pumping induced output voltage owing to the molecular
hybridization. The non-collinear Density Functional Theory calculations confirm
the long-range enhancement of SOC of $\beta$-W upon the chemisorption of C60
molecules, which in turn can also enhance the SOC at the CFB/$\beta$-W
interface in CFB/$\beta$-W/C60 heterostructures. The combined amplification of
bulk as well interfacial SOC upon molecular hybridization stabilizes the
anti-damping and enhanced spin-to-charge conversion, which can pave the way for
the fabrication of power efficient spintronics devices.",2401.00486v1
2024-01-11,Instability windows of relativistic r-modes,"The detectability of the gravitational-wave signal from $r$-modes depends on
the interplay between the amplification of the mode by the CFS instability and
its damping due to dissipative mechanisms present in the stellar matter. The
instability window of $r$-modes describes the region of stellar parameters
(angular velocity, $\Omega$, and redshifted stellar temperature, $T^\infty$),
for which the mode is unstable. In this study, we reexamine this problem in
nonbarotropic neutron stars, taking into account the previously overlooked
nonanalytic behavior (in $\Omega$) of relativistic $r$-modes and enhanced
energy dissipation resulting from diffusion in superconducting stellar matter.
We demonstrate that at slow rotation rates, relativistic $r$-modes exhibit
weaker amplification by the CFS instability compared to Newtonian ones.
However, their dissipation through viscosity and diffusion is significantly
more efficient. In rapidly rotating neutron stars within the framework of
general relativity, the amplification of $r$-modes by the CFS mechanism and
their damping due to shear viscosity become comparable to those predicted by
Newtonian theory. In contrast, the relativistic damping of the mode by
diffusion and bulk viscosity remains significantly stronger than in the
nonrelativistic case. Consequently, account for diffusion and general
relativity leads to a substantial modification of the $r$-mode instability
window compared to the Newtonian prediction. This finding is important for the
interpretation of observations of rotating neutron stars, as well as for
overall understanding of $r$-mode physics.",2401.06200v1
2024-02-02,Controllable frequency tunability and parabolic-like threshold current behavior in spin Hall nano-oscillators,"We investigate the individual impacts of critical magnetodynamical
parameters-effective magnetization and magnetic damping-on the auto-oscillation
characteristics of nano-constriction-based Spin Hall Nano-Oscillators (SHNOs).
Our micromagnetic simulations unveil a distinctive non-monotonic relationship
between current and auto-oscillation frequency in out-of-plane magnetic fields.
The influence of effective magnetization on frequency tunability varies with
out-of-plane field strengths. At large out-of-plane fields, the frequency
tunability is predominantly governed by effective magnetization, achieving a
current tunability of 1 GHz/mA-four times larger than that observed at the
lowest effective magnetization. Conversely, at low out-of-plane fields,
although a remarkably high-frequency tunability of 4 GHz/mA is observed, the
effective magnetization alters the onset of the transition from a linear-like
mode to a spin-wave bullet mode. Magnetic damping primarily affects the
threshold current with negligible impact on auto-oscillation frequency
tunability. The threshold current scales linearly with increased magnetic
damping at a constant out-of-plane field but exhibits a parabolic behavior with
variations in out-of-plane fields. This behavior is attributed to the
qualitatively distinct evolution of the auto-oscillation mode across different
out-of-plane field values. Our study not only extends the versatility of SHNOs
for oscillator-based neuromorphic computing with controllable frequency
tunability but also unveils the intricate auto-oscillation dynamics in
out-of-plane fields.",2402.01570v1
2024-02-06,The fermion self-energy and damping rate in a hot magnetized plasma,"We derive a general expression for the fermion self-energy in a hot
magnetized plasma by using the Landau-level representation. In the one-loop
approximation, the Dirac structure of the self-energy is characterized by five
different functions that depend on the Landau-level index $n$ and the
longitudinal momentum $p_z$. We derive general expressions for all five
functions and obtain closed-form expressions for their imaginary parts. The
latter receive contributions from three types of on-shell processes, which are
interpreted in terms of Landau-level transitions, accompanied by a single
photon (gluon) emission or absorption. By making use of the imaginary parts of
the self-energy functions, we also derive the Landau-level dependent fermion
damping rates $\Gamma_{n}(p_z)$ and study them numerically in a wide range of
model parameters. We also demonstrate that the two-spin degeneracy of the
Landau levels is lifted by the one-loop self-energy corrections. While the spin
splitting of the damping rates is small, it may be important for some spin and
chiral effects. We argue that the general method and the numerical results for
the rates can have interesting applications in heavy-ion physics, astrophysics,
and cosmology, where strongly magnetized QED or QCD plasmas are ubiquitous.",2402.04307v2
2024-03-18,Radiative loss and ion-neutral collisional effects in astrophysical plasmas,"In this paper we study the role of radiative cooling in a two-fluid model
consisting of coupled neutrals and charged particles. We first analyze the
linearized two-fluid equations where we include radiative losses in the energy
equation for the charged particles. In a 1D geometry for parallel propagation
and in the limiting cases of weak and strong coupling, it can be shown
analytically that the instability conditions for the thermal mode and the sound
waves, the isobaric and isentropic criteria, respectively, remain unchanged
with respect to one-fluid radiative plasmas. For the parameters considered in
this paper, representative for the solar corona, the radiative cooling produces
growth of the thermal mode and damping of the sound waves. When neutrals are
included and are sufficiently coupled to the charges, the thermal mode growth
rate and the wave damping both reduce by the same factor, which depends on the
ionization fraction only. For a heating function which is constant in time, we
find that the growth of the thermal mode and the damping of the sound waves are
slightly larger. The numerical calculation of the eigenvalues of the general
system of equations in a 3D geometry confirm the analytic results. We then run
2D fully nonlinear simulations which give consistent results: a higher
ionization fraction or lower coupling will increase the growth rate. The
magnetic field contribution is negligible in the linear phase.
Ionization-recombination effects might play an important role because the
radiative cooling produces a large range of temperatures in the system. In the
numerical simulation, after the first condensation phase, when the minimum
temperature is reached, the fraction of neutrals increases four orders of
magnitude because of the recombination.",2403.11900v1
2024-04-02,A new gap in the critical exponent for semi-linear structurally damped evolution equations,"Our aim in this paper is to discuss the critical exponent in semi-linear
structurally damped wave and beam equations with additional dispersion term.
The special model we have in mind is $$
u_{tt}(t,x)+(-\Delta)^{\sigma}u(t,x)+(-\Delta)^{2\delta}u(t,x)+2(-\Delta)^{\delta}u_{t}(t,x)=\left|u(t,x)\right|
^{p} $$ where the initial displacement $u(0,x)=u_{0}(x)$, the initial velocity
$u_{t}(0,x)=u_{1}(x)$ and the parameters $ t\in [0,\infty)$, $x\in
\mathbb{R}^{n}$, $\sigma\geq 1$, $\delta\in(0,\frac{\sigma}{2})$, $p>1$. The
solution to the linear equation at low frequency region involves an interplay
of diffusion and oscillation phenomena represented by a real-complex Fourier
multiplier of the form $$m(t,\xi)=\frac{e^{-|\xi|^{2\delta}t\pm
i|\xi|^{\sigma}t}}{2i|\xi|^{\sigma}}, \ \ \xi\in \mathbb{R}^{n}, \ \
i=\sqrt{-1}.$$ The scaling argument shows that the diffusive part leads to
faster decay rates compared to the oscillatory one. This interplay creates a
new gap in the critical exponent between the blow up (in finite time) result
when $1<p<1+\frac{4\delta}{n-2\delta}$ (sub-critical case) and the global (in
time) existence result when $p>1+\frac{\sigma+2\delta}{n-\sigma}$
(super-critical case). We leave an open to show if this gap will be closed at
least in low or high space dimensions because, to the best of authors
knowledge, the necessary Fourier multiplier that leads to the sub-critical case
does not explicitly appear in $m(t,\xi)$.",2404.01544v1
1999-07-23,Autoregressive model of 1/f noise,"An analytically solvable model is proposed exhibiting 1/f spectrum in any
desirably wide range of frequency (but excluding the point f=0). The model
consists of pulses whose recurrence times obey an autoregressive process with
very small damping.",9907008v1
1996-08-22,Evolution of Neutral Gas at High Redshift -- Implications for the Epoch of Galaxy Formation,"Though observationally rare, damped Lya absorption systems dominate the mass
density of neutral gas in the Universe. Eleven high redshift damped Lya systems
covering 2.8<z<4.4 were discovered in 26 QSOs from the APM z>4 QSO Survey,
extending these absorption system surveys to the highest redshifts currently
possible. Combining our new data set with previous surveys we find that the
cosmological mass density in neutral gas, omega_g, does not rise as steeply
prior to z~2 as indicated by previous studies. There is evidence in the
observed omega_g for a flattening at z~2 and a possible turnover at z~3. When
combined with the decline at z>3.5 in number density per unit redshift of
damped systems with column densities log N(HI)>21 atoms cm^-2, these results
point to an epoch at z>3 prior to which the highest column density damped
systems are still forming. We find that over the redshift range 2<z<4 the total
mass in neutral gas is marginally comparable with the total visible mass in
stars in present day galaxies. However, if one considers the total mass visible
in stellar disks alone, ie excluding galactic bulges, the two values are
comparable. We are observing a mass of neutral gas comparable to the mass of
visible disk stars. Lanzetta, Wolfe & Turnshek (1995) found that omega_g(z~3.5)
was twice omega_g(z~2), implying a much larger amount of star formation must
have taken place between z=3.5 and z=2 than is indicated by metallicity
studies. This created a `cosmic G-dwarf problem'. The more gradual evolution of
omega_g we find alleviates this. These results have profound implications for
theories of galaxy formation.",9608147v1
1997-07-14,Damped Lyman-alpha Absorption Associated with an Early-Type Galaxy at Redshift z = 0.16377,"We report new HST and ground-based observations of a damped Lyman-alpha
absorption system toward the QSO 0850+4400. The redshift of the absorption
system is z = 0.163770 and the neutral hydrogen column density of the
absorption system is log N = 19.81 cm**-2. The absorption system is by far the
lowest redshift confirmed damped Lyman-alpha absorption system yet identified,
which provides an unprecedented opportunity to examine the nature, impact
geometry, and kinematics of the absorbing galaxy in great detail. The
observations indicate that the absorption system is remarkable in three
respects: First, the absorption system is characterized by weak metal
absorption lines and a low metal abundance, possibly less than 4% of the solar
metal abundance. This cannot be explained as a consequence of dust, because the
neutral hydrogen column density of the absorption system is far too low for
obscuration by dust to introduce any significant selection effects. Second, the
absorption system is associated with a moderate-luminosity early-type S0
galaxy, although the absorption may actually arise in one of several very faint
galaxies detected very close to the QSO line of sight. Third, the absorbing
material moves counter to the rotating galaxy disk, which rules out the
possibility that the absorption arises in a thin or thick co-rotating gaseous
disk. These results run contrary to the expectation that low-redshift damped
Lyman-alpha absorption systems generally arise in the gas- and metal-rich inner
parts of late-type spiral galaxies. We suggest instead that mounting evidence
indicates that low-redshift galaxies of a variety of morphological types may
contain significant quantities of low metal abundance gas at large
galactocentric distances.",9707157v1
1997-08-27,Reionization of the Intergalactic Medium and the Damping Wing of the Gunn-Peterson Trough,"Observations of high-redshift quasars show that the IGM must have been
reionized at some redshift $z>5$. If a source of radiation could be observed at
the rest-frame Lya wavelength, at a sufficiently high redshift where some of
the IGM in the line-of-sight was not yet reionized, the Gunn-Peterson trough
should be present. Longward of the Lya wavelength, a damping wing should be
observed caused by the neutral IGM whose absorption profile can be predicted.
Measuring the shape of this damping wing would provide irrefutable evidence of
the observation of the IGM before reionization, and a determination of the
density of the neutral IGM. This measurement might be hindered by the possible
presence of a dense absorption system associated with the source.
  Shortward of the \lya wavelength, absorption should be seen from the patchy
structure of the IGM in the process of reionization. We show that a complete
Gunn-Peterson trough is most likely to continue to be observed through the
epoch where the IGM is partially ionized. The damping wings of the neutral
patches should overlap if the proper pathlength through an ionized region is
less than 1 h^{-1} Mpc; even in larger ionized regions, the characteristic
background intensity should be low enough to yield a very high optical depth
due to the residual neutral fraction, although occasionally some flux may be
transmitted through large, underdense voids within an ionized region. The case
of the HeII reionization is also discussed, and we argue that helium was
already doubly ionized by z=3 throughout the IGM.
  The recently discovered afterglows of gamma-ray bursts might soon be observed
at very high redshifts. Their featureless continuum spectrum and high
luminosities make them ideal sources for studying absorption by the IGM.",9708253v1
1997-09-16,On the nature of z(abs) ~ z(em) damped absorbers in quasar spectra,"We present spectroscopic observations of the damped Ly-alpha absorber at
redshift z=1.9342 seen in the spectrum of the quasar Q0151+048A. The redshift
of the absorber is greater than the redshift of the quasar, so the system
resembles the z(abs) ~ z(em) damped absorber at z=2.81 towards the quasar
PKS0528-250. We have previously reported the detection of Ly-alpha emission
from the latter absorber, one of only two damped absorbers for which Ly-alpha
emission has unambiguously been detected. The resemblance between the
PKS0528-250 and Q0151+048A systems is made closer by the detection of a weak
emission feature in the trough of the Q0151+048A absorber. This leads us to
consider whether these z(abs) ~ z(em) DLA absorbers are different objects to
the intervening DLA absorbers. Two possibilities are examined and rejected.
Firstly the Q0151+048A and PKS0528-250 z(abs) ~ z(em) absorbers appear to be
unrelated to the intrinsic absorbers (i.e. gas close to the quasar nucleus,
ejected by the quasar), as intrinsic absorbers are of higher metallicity, have
higher ionisation parameter, and show complex absorption profiles. Secondly
these two DLA absorbers cannot be equated with the gaseous disks of the quasar
host galaxies, as the absorber redshifts differ significantly from the quasar
systemic redshifts. It is likely, then, that intrinsically the z(abs) ~ z(em)
DLA absorbers are the same as the intervening DLA absorbers, so that
peculiarities in some of the z(abs) ~ z(em) absorbers can be ascribed to their
different environment i.e. proximity to the quasar, or membership of the same
cluster as the quasar. We point out that the proximity effect may play some
role, by reducing the Ly-alpha forest line blanketing of any Ly-alpha emission
line from z(abs) ~ z(em) absorbers.",9709160v1
1998-01-15,A HST Spectroscopic study of QSOs with intermediate redshift damped Lyman-alpha systems,"We present HST spectra for a sample of six QSOs with intermediate redshift
(z_a < 1) damped Ly-alpha systems. These observations aim at measuring the HI
column density and detect metal lines in order to investigate the metal
enrichment of the gas, as well as the presence of neutral species, molecules
and dust. All systems selected on the basis of 21 cm absorption and/or strong
FeII lines relative to MgII ones turn out to have N(HI) larger than 10^20 cm-2.
It appears that although the scatter of metallicities is as large at z_a<1 as
at high redshift, an increasing proportion of systems with metallicities ~ 30%
solar are found when going at lower redshifts. Our results suggest that
available observations may be biased against dust-rich absorbers. Further, when
all available measurements of N(HI) and [Zn/H] are considered, a clear
deficiency of systems with large N(HI) and high metallicity is apparent. We
conclude that dust extinction causes a preferential selection of QSOs with
intervening gas relatively poor in metals, dust and molecules. As a
consequence, the high end of the HI column density distribution (and hence
Omega_g, the contribution of neutral gas to the cosmological mass density) is
probably more heavily underestimated than previously thought, especially at low
redshift. Such a bias could also explain the high incidence of non-spiral
morphologies in our sample. We stress that observation of a larger sample of
low z damped Ly-alpha systems as well as surveys of damped Ly-alpha systems in
fainter QSOs would give a more representative view of the true diversity of
absorber properties and should help to probe the denser phases of the
interstellar medium in distant galaxies.",9801146v1
1998-06-15,On the kinematics of damped Lyman-alpha systems,"We report on high spectral resolution observations of five damped Ly-alpha
absorbers. Line velocity profiles and heavy element abundances are discussed.
Nitrogen is found to have abundances less than silicon in the systems toward Q
0347-383, Q 0913+072, and Q 1213+093. The absorber toward Q 0913+072 is the
most metal-deficient damped system known, with [Fe/H] < -3.2. The simple
kinematical structure of the metal absorptions makes this system ideal to
discuss the [O/Si] and [N/O] ratios. We find [O/H] ~ -2.7 and -2.7 < [Si/H] <
-2.2. By combining these data with information gathered in the literature, we
study the kinematics of the low and high ionization phases in a sample of 26
damped Ly-alpha systems in the redshift range 1.17-4.38. We note a strong
correlation between the velocity broadenings of the SiII,1808 and FeII,1608
lines whatever the line optical depth, implying that the physical conditions
are quite homogeneous in the sample. Statistically this shows that large
variations of abundance ratios and thus large variations of depletion into dust
grains are unlikely. The velocity broadening of the absorption lines, Delta V,
is correlated with the asymmetry of the lines for Delta V < 150 km/s. The
broader the line the more asymmetric it is, as expected in case rotation
dominates the line broadening. However this correlation does not hold for
larger Delta V suggesting that evidence for rotational motions is restricted to
velocity broadenings Delta V < 150 km/s. The systems with Delta V > 200 km/s
are peculiar with kinematics consistent with random motions. They show
sub-systems as those expected if the objects are in the process of merging
(abridged).",9806202v1
1999-10-07,Si and Mn Abundances in Damped Lya Systems with Low Dust Content,"We have measured the abundances of Zn, Si, Mn, Cr, Fe, and Ni in three damped
Lyman alpha systems at redshifts z < 1 from high resolution echelle spectra of
QSOs recorded with the Keck I telescope. In all three cases the abundances of
Cr, Fe, and Ni relative to Zn indicate low levels of dust depletions. We
propose that when the proportion of refractory elements locked up in dust
grains is less than about 50 percent, it is plausible to assume an
approximately uniform level of depletion for all grain constituents and, by
applying a small dust correction, recover the intrisic abundances of Si and Mn.
We use this approach on a small sample of damped systems for which it is
appropriate, with the aim of comparing the metallicity dependence of the ratios
[Si/Fe] and [Mn/Fe] with analogous measurements in Milky Way stars. The main
conclusion is that the relative abundances of both elements in distant galaxies
are broadly in line with expectations based on Galactic data. Si displays a
mild enhancement at low metallicities, as expected for an alpha-capture
element, but there are also examples of near-solar [Si/Fe] at [Fe/H] < -1. The
underabundance of Mn at low metallicities is possibly even more pronounced than
that in metal-poor stars, and no absorption system has yet been found where
[Mn/Fe] is solar. The heterogeneous chemical properties of damped Lyman alpha
systems, evident even from this limited set of measurements, provide further
support for the conclusion from imaging studies that a varied population of
galaxies gives rise to this class of QSO absorbers.",9910131v1
1999-11-23,On the orbital evolution and growth of protoplanets embedded in a gaseous disc,"We present a new computation of the linear tidal interaction of a
protoplanetary core with a thin gaseous disc in which it is fully embedded. For
the first time a discussion of the orbital evolution of cores with eccentricity
(e) significantly larger than the gas-disc scale height to radius ratio (H/r)
is given. We find that the direction of orbital migration reverses for
e>1.1H/r. This occurs as a result of the orbital crossing of resonances in the
disc that do not overlap the orbit when the eccentricity is very small. Simple
expressions giving approximate fits to the eccentricity damping rate and the
orbital migration rate are presented. We go on to calculate the rate of
increase of the mean eccentricity for a system of protoplanetary cores due to
dynamical relaxation. By equating the eccentricity damping time-scale with the
dynamical relaxation time-scale we deduce that an equilibrium between
eccentricity damping and excitation through scattering is attained on a 10^3 to
10^4 yr time-scale, at 1au. The equilibrium thickness of the protoplanet
distribution is such that it is generally well confined within the gas disc. By
use of a three dimensional N-body code we simulate the evolution of a system of
protoplanetary cores, incorporating our eccentricity damping and migration
rates. Assuming that collisions lead to agglomeration, we find that the
vertical confinement of the protoplanet distribution permits cores to build up
from 0.1 to 1 earth mass in only ~10^4 yr, within 1au. The time-scale required
to achieve this is comparable to the migration time-scale. We deduce that it is
not possible to build up a massive enough core to form a gas giant planet
before orbital migration ultimately results in the preferential delivery of all
such bodies to the neighbourhood of the central star. [Abridged]",9911431v1
1999-12-14,Finding typical high redshift galaxies with the NOT,"We present results from an ongoing search for galaxy counterparts of a
subgroup of Quasar Absorption Line Systems called Damped Ly-alpha Absorbers
(DLAs). DLAs have several characteristics that make them prime candidates for
being the progenitors of typical present day galaxies.",9912278v1
2000-10-21,UVES observations of QSO 0000-2620: Argon and Phosphorus abundances in the dust-free damped Ly-alpha system at zabs = 3.3901,"The UV resonance transitions of neutral argon ArI 1066 A, and of singly
ionized phosphorus PII 963 A, originated in the damped Ly_alpha system (DLA) at
zabs = 3.3901 towards QSO 0000--2620 have been detected by means of the UVES
spectrograph at the 8.2m ESO KUEYEN telescope. So far, this is the first
measurement of ArI, and the second of PII, ever performed in damped galaxies
and in high redshift objects. This DLA is well known for having one of the
lowest metal abundances and dust content, and the lowest fractional abundance
of molecular hydrogen H_2. The measured Ar abundance is [Ar/H] = - 1.91 (+/-
0.09) which is equal to the abundances of the other alpha-chain elements (O, S
and Si). The similarity of the Ar abundance with the other alpha-chain elements
implies the absence of significant photoionization by either UV background or
stellar sources along the sightline throughout the damped Ly_alpha system. Both
log(Ar/O) and log(Ar/S) ratios are found close to those measured in the
extragalactic HII regions and in blue compact galaxies where O is more abundant
by at least one order of magnitude. This strengthens the universality of the
Ar/O and Ar/S ratios and lends support to the existence of a universal IMF. The
abundance of the non-refractory element phosphorus [P/H] = - 2.31 (+/- 0.10)
confirms the low amount of chemical evolution in the DLA. This is the
measurement of P in the most metal-poor material and shows a subsolar [P/Fe] =
--0.27 value. The measured ratios [P/Si] = - 0.40 (+/- 0.13) and [P/S] = - 0.33
(+/- 0.13) provide evidence for a mild odd-even effect. Finally, a stringent
upper limit to the population of the 3P_1 level in the ground state of OI is
derived, which provides a lower limit to the physical dimensions of the zabs =
3.3901 system of L > 7 pc.",0010434v1
2001-09-21,Coincidences of high density peaks in UVES spectra of QSO pairs,"We present preliminary results of an investigation of the clustering
properties of high matter density peaks between redshift ~2 and ~3, as traced
by Lyman limit and Damped Ly-alpha systems in spectra of close QSO pairs and
groups.",0109373v1
2002-01-31,Electron impact excitation of helium-like oxygen up to n = 4 levels including radiation damping,"The primary X-ray diagnostic lines in He-like ions are mainly excited by
electron impact from the ground level to the n = 2 levels, but at high
temperatures n > 2 levels are also excited. In order to describe the atomic
processes more completely collision strengths are computed for OVII including
for the first time all of the following: (i) relativistic fine structure, (ii)
levels up to the n = 4, and (iii) radiation damping of autoionizing resonances.
The calculations are carried out using the Breit-Pauli R-matrix (BPRM) method
with a 31-level eigenfunction expansion. Resonance structures in collision
strengths are delineated in detail up to the n = 4 thresholds. For highly
charged He-like ions radiation damping of autoionizing resonances is known to
be significant. We investigate this effect in detail and find that while
resonances are discernibly damped radiatively as the series limit n --> infty
is approached from below, the overall effect on effective cross sections and
rate coefficients is found to be very small. Collision strengths for the
principal lines important in X-ray plasma diagnostics, w,x,y and z,
corresponding to the 4 transitions to the ground level 1s^2 (^1S_0) <-- 1s2p
(^1P^o_1), 1s2p (^3P^o_2), 1s2p (^3P^o_1), 1s2s (^3S_1), are explicitly shown.
It is found that the effective collision strength of the forbidden z-line is up
to a factor of 4 higher at T < 10^6 K than previous values. This is likely to
be of considerable importance in the diagnostics of photoionized astrophysical
plasmas. Significant differences are also found with previous works for several
other transitions. This work is carried out as part of the Iron Project-RmaX
Network.",0201535v1
2002-12-07,Improved Bounds on Violation of the Strong Equivalence Principle,"I describe a unique, 20-year-long timing program for the binary pulsar
B0655+64, the stalwart control experiment for measurements of gravitational
radiation damping in relativistic neutron-star binaries. Observed limits on
evolution of the B0655+64 orbit provide new bounds on the existence of dipolar
gravitational radiation, and hence on violation of the Strong Equivalence
Principle.",0212180v1
2004-04-13,The Fine-structure Constant as a Probe of Chemical Evolution and AGB Nucleosynthesis in Damped Lyman-alpha Systems,"Evidence from a large sample of quasar absorption-line spectra in damped
Lyman-alpha systems has suggested a possible time variation of the fine
structure constant alpha. The most statistically significant portion of this
sample involves the comparison of Mg and Fe wavelength shifts using the
many-multiplet (MM) method. However, the sensitivity of this method to the
abundance of heavy isotopes, especially Mg, is enough to imitate an apparent
variation in alpha in the redshift range 0.5 < z < 1.8. We implement recent
yields of intermediate mass (IM) stars into a chemical evolution model and show
that the ensuing isotope distribution of Mg can account for the observed
variation in alpha provided the early IMF was particularly rich in intermediate
mass stars (or the heavy Mg isotope yields from AGB stars are even higher than
in present-day models). As such, these observations of quasar absorption
spectra can be used to probe the nucleosynthetic history of low-metallicity
damped Lyman-alpha systems in the redshift range 0.5 < z < 1.8. This analysis,
in conjunction with other abundance measurements of low-metallicity systems,
reinforces the mounting evidence that star formation at low metallicities may
have been strongly influenced by a population of IM stars. Such IM stars have a
significant influence on other abundances, particularly nitrogen. We constrain
our models with independent measurements of N, Si, and Fe in damped Lyman-alpha
systems as well as C/O in low-metallicity stars. In this way, we obtain
consistent model parameters for this chemical-evolution interpretation of the
MM method results.",0404257v2
2006-01-23,"Bulk viscosity of a gas of neutrinos and coupled scalar particles, in the era of recombination","Bulk viscosity may serve to damp sound waves in a system of neutrinos coupled
to very light scalar particles, in the era after normal neutrino decoupling but
before recombination. We calculate the bulk viscosity parameter in a minimal
scheme involving the coupling of the two systems. We add some remarks on the
bulk viscosity of a system of fully ionized hydrogen plus photons.",0601525v1
2006-09-28,Turbulent Comptonization in Relativistic Accretion Disks,"Turbulent Comptonization, a potentially important damping and radiation
mechanism in relativistic accretion flows, is discussed. Particular emphasis is
placed on the physical basis, relative importance, and thermodynamics of
turbulent Comptonization. The effects of metal-absorption opacity on the
spectral component resulting from turbulent Comptonization is considered as
well.",0609797v1
1994-05-16,Bifurcations of two coupled classical spin oscillators,"Two classical, damped and driven spin oscillators with an isotropic exchange
interaction are considered. They represent a nontrivial physical system whose
equations of motion are shown to allow for an analytic treatment of local
codimension 1 and 2 bifurcations. In addition, numerical results are presented
which exhibit a Feigenbaum route to chaos.",9405011v1
1998-04-02,The Decay Properties of the Finite Temperature Density Matrix in Metals,"Using ordinary Fourier analysis, the asymptotic decay behavior of the density
matrix F(r,r') is derived for the case of a metal at a finite electronic
temperature. An oscillatory behavior which is damped exponentially with
increasing distance between r and r' is found. The decay rate is not only
determined by the electronic temperature, but also by the Fermi energy. The
theoretical predictions are confirmed by numerical simulations.",9804013v1
1998-12-02,Dissipative properties of vibrated granular materials,"We investigate collective dissipative properties of vibrated granular
materials by means of molecular dynamics simulations. Rates of energy losses
indicate three different regimes or ""phases""in the amplitude-frequency plane of
the external forcing, namely, solid, convective, and gas-like regimes. The
behavior of effective damping decrement in the solid regime is glassy.
Practical applications are dicussed.",9812036v1
1999-01-14,Spin dynamics in the generalized ferromagnetic Kondo model for manganites,"Dynamical spin susceptibility is calculated for the generalized ferromagnetic
Kondo model which describes itinerant $e_{g}$ electrons interacting with
localized $t_{2g}$ electrons with antiferromagnetic coupling. The calculations
done in the mean field approximation show that the spin-wave spectrum of the
system in ferromagnetic state has two branches, acoustic and optic ones.
Self-energy corrections to the spectrum are considered and the acoustic
spin-wave damping is evaluated.",9901141v1
1999-10-01,Properties of excitations in systems with a spinor Bose-Einstein condensate,"General theory in case of homogenous Bose-Einstein condensed systems with
spinor condensate is presented for the correlation functions of density and
spin fluctuations and for the one-particle propagators as well. The random
phase approximation is investigated and the damping of the modes is given in
the intermediate temperature region. It is shown that the collective and the
one-particle excitation spectra do not coincide fully.",9910010v1
2001-07-16,Anomalous Levy decoherence,"We investigate the decoherence of a small quantum system weakly coupled to a
complex, chaotic environment when the dynamics is not Gaussian but Levy
anomalous. By studying the time dependence of the linear entropy and the
damping of the interference of two Gaussian wave packets in the Wigner
representation, we show that the decoherence time for a quantum Levy stable
process is always smaller than for Gaussian diffusion.",0107344v1
2001-09-05,Nuclear resonant scattering of Synchrotron radiation from nuclei in the Browninan motion,"The time evolution of the coherent forward scattering of Synchrotron
radiation for resonant nuclei in Brownian motion is studied . Apart from target
thickness, the appearance of dynamical beats also depends on $\alpha$ which is
the ratio of harmonic force constant to the damping force constant of a
harmonic oscillator undergoing Brownian motion.",0109074v2
2002-03-06,Effect of electron-phonon interaction on the shift and attenuation of optical phonons,"Using the Boltzmann equation for electrons in metals, we show that the
optical phonons soften and have a dispersion due to screening in agreement with
the results reported recently [M. Reizer, Phys. Rev. B {\bf 61}, 40 (2000)].
Additional phonon damping and frequency shift arise when the electron--phonon
interaction is properly included.",0203112v1
2002-04-09,Spatial resolution of spin waves in an ultra-cold gas,"We present the first spatially resolved images of spin waves in a gas. The
complete longitudinal and transverse spin field as a function of time and space
is reconstructed. Frequencies and damping rates for a standing-wave mode are
extracted and compared with theory.",0204182v1
2002-08-14,Three-wave mixing of Bogoliubov quasi-particles in a Bose condensate,"A dressed basis is used to calculate the dynamics of three-wave mixing
between Bogoliubov quasi-particles in a Bose condensate. Due to the observed
oscillations between different momenta modes, an energy splitting, analogous to
the optical Mollow triplet, appears in the Beliaev damping spectrum of the
excitations from the oscillating modes.",0208283v2
2002-11-08,"Reply on ``Fluctuation-dissipation considerations for phenomenological damping models for ferromagnetic thin films'' [N. Smith, J. Appl. Phys. \bf{92}, 3877 (2002)]","We show that the critique of our recent papers presented in the
abovementioned paper (NS) appeals to an incorrect mathematical analogy between
electrical circuits and linear magnetization dynamics, improperly uses
classical concepts of normal modes and basic equations, gives inconsistent
results and therefore comes to incorrect conclusions.",0211147v1
2003-02-04,Squeezing and temperature measurement in Bose-Einstein Condensates,"In this paper we discuss the presence of temperature-dependent squeezing in
the collective excitations of trapped Bose-Einstein condensates, based on a
recent theory of quasiparticle damping. A new scheme to measure temperature
below the critical temperature is also considered.",0302068v1
2003-03-12,Time-Dependent Dynamics of the Bose-Fermi Mixed Condensed System,"We study the monopole oscillation in the bose-fermi mixed condensed system by
performing the time-dependent Gross-Pitaevsky (GP) and Vlasov equations. We
find that the big damping exists for the fermion oscillation in the mixed
system even at zero temperature",0303216v1
2005-10-06,Thermal processes induced in carbon nanotubes by attosecond laser pulses,"In this paper the heat transport in carbon nanotubes is investigated. When
the dimension of the structure is of the order of the de Broglie wave length
the transport phenomena must be analyzed within quantum mechanics. In this
paper we developed the Dirac type thermal equation. The solution of the
equation the temperature fields for electrons can be damped or can oscillate
depending on the dynamics of the scattering.",0510141v1
2006-08-22,Simulation of stress-impedance effects in low magnetostrictive films,"A theoretical study of stress-impedance effect based on the solution of
Landau-Lifsitz-Gilbert equation has been carried out. The results show that
stress impedance effects depend largely on several extrinsic (external bias
field, external frequency) and intrinsic (orientation and magnitude of uniaxial
anisotropy, damping) parameters.",0608488v1
2006-09-05,Lifetimes of electrons in the Shockley surface state band of Ag(111),"We present a theoretical many-body analysis of the electron-electron (e-e)
inelastic damping rate $\Gamma$ of electron-like excitations in the Shockley
surface state band of Ag(111). It takes into account ab-initio band structures
for both bulk and surface states. $\Gamma$ is found to increase more rapidly as
a function of surface state energy E than previously reported, thus leading to
an improved agreement with experimental data.",0609080v1
2006-09-28,Transition-Event Durations in One Dimensional Activated Processes,"Despite their importance in activated processes, transition-event durations
-- which are much shorter than first passage times -- have not received a
complete theoretical treatment. We therefore study the distribution of
durations of transition events over a barrier in a one-dimensional system
undergoing over-damped Langevin dynamics.",0609741v1
2007-01-08,Coefficient of restitution for viscoelastic disks,"The dissipative collision of two identical viscoelastic disks is studied. By
using a known law for the elastic part of the interaction force and the
viscoelastic damping model an analytical solution for the coefficient of
restitution shall be given. The coefficient of restitution depends
significantly on the impact velocity. It approaches one for small velocities
and decreases for increasing velocities.",0701142v1
2007-01-09,Enhanced Weiss oscillations in graphene,"The magneto-conductivity of a single graphene layer where the electrons are
described by the Dirac Hamiltonian weakly modulated by a periodic potential is
calculated. It is shown that Weiss oscillations periodic in the inverse
magnetic field appear, that are more pronounced and less damped with the
increment of temperature as compared with the same oscillations in a typical
two-dimensional electron system with a standard parabolic energy spectrum.",0701175v1
2007-03-15,A new electromagnetic mode in graphene,"A new, weakly damped, {\em transverse} electromagnetic mode is predicted in
graphene. The mode frequency $\omega$ lies in the window
$1.667<\hbar\omega/\mu<2$, where $\mu$ is the chemical potential, and can be
tuned from radiowaves to the infrared by changing the density of charge
carriers through a gate voltage.",0703406v1
1997-04-01,Controversies in the History of the Radiation Reaction problem in General Relativity,"This paper examines the historical controversy over whether gravitationally
bound systems, such as binary stars, experienced orbital damping due to the
emission of gravitational radiation, focusing especially on the period of the
1950s, but also discussing the work of Einstein and Rosen in the 1930s on
cylindrical gravitational waves and the later quadrupole formula controversy.",9704002v1
2000-11-14,Binary black holes coalescence: transition from adiabatic inspiral to plunge,"Using two recent techniques giving non-perturbative re-summed estimates of
the damping and of the conservative part of the dynamics of two-body systems,
we describe the transition between adiabatic inspiral and plunge in binary
non-spinning black holes moving along quasi-circular orbits.",0011052v1
2004-06-24,Hawking temperature from quasi-normal modes,"A perturbed black hole has characteristic frequencies (quasi-normal modes).
Here I apply a quantum measurement analysis of the quasi-normal mode frequency
in the limit of high damping. It turns out that a measurement of this mode
necessarily adds noise to it. For a Schwarzschild black hole, this corresponds
exactly to the Hawking temperature. The situation for other black holes is
briefly discussed.",0406097v1
2005-08-10,Quasinormal modes of Unruh's Acoustic Black Hole,"We have studied the sound perturbation of Unruh's acoustic geometry and we
present an exact expression for the quasinormal modes of this geometry. We are
obtain that the quasinormal frequencies are pure-imaginary, that give a purely
damped modes.",0508040v2
2005-08-12,Self-similar and charged spheres in the diffusion approximation,"We study spherical, charged and self--similar distributions of matter in the
diffusion approximation. We propose a simple, dynamic but physically meaningful
solution. For such a solution we obtain a model in which the distribution
becomes static and changes to dust. The collapse is halted with damped mass
oscillations about the absolute value of the total charge.",0508055v1
2006-12-01,Quasinormal modes of gravitational perturbation around a Schwarzschild black hole surrounded by quintessence,"In this paper, the quasinormal modes of gravitational perturbation around a
Schwarzschild black hole surrounded by quintessence were evaluated by using the
third-order WKB approximation. Due to the presence of quintessence, the
gravitational wave damps more slowly.",0612009v1
1992-09-14,Lyapunov Exponent of SU(3) Gauge Theory,"The classical SU(3) gauge theory is shown to be deterministic chaotic. Its
largest Lyapunov exponent is dertermined, from which a short time scale of
thermalization of a pure gluon system is estimated. The connection to gluon
damping rate is discussed.",9209018v1
1993-06-11,Coherence and Decoherence in Radiation off Colliding Heavy Ions,"We discuss the kinetics of a disoriented chiral condensate, treated as an
open quantum system. We suggest that the problem is analogous to that of a
damped harmonic oscillator. Master equations are used to establish a hierarchy
of relevant time scales. Some phenomenological consequences are briefly
outlined.",9306260v1
1995-01-06,Thermal Two Point Function of a Heavy Muon in hot QED plasma within Bloch Nordsieck Approximation,"The thermal propagator of a heavy muon propagating in a hot QED plasma is
examined within the Bloch-Nordsieck approximation, which is valid in the
infrared region. It is shown that the muon damping rate is finite, in contrast
to the lower-order calculation with hard thermal loop resummations taken into
account.",9501223v1
1997-08-29,Numerical study of plasmon properties in the SU(2)-Higgs model,"We discuss an explorative computation of real time autocorrelation functions,
in the classical approximation. The results for the `plasmon' frequencies and
damping rates appear compatible with the divergencies expected from
perturbation theory.",9708493v1
1999-07-31,Structure of the Quark Propagator at High Temperature,"In the high temperature, chirally invariant phase of QCD, the quark
propagator is shown to have two sets of poles with different dispersion
relations. A reflection property in momentum space relates all derivatives at
zero-momentum of the particle and hole energies, the particle and hole damping
rates, and the particle and hole residues. No use is made of perturbation
theory.",9908204v1
1999-11-12,Covariant Perturbation Theory of Non-Abelian Kinetic Theory,"A double perturbation idea is presented in framework of the quark-gluon
plasma kinetic theory. A solvable set of equations from the 'double
perturbation' is derived and the equations are showed to be gauge-independent.
The formalism of Landau damping rate for the plasmon at zero momentum is given
and discussed.",9911325v2
2000-10-25,Resummation and damping in the O(N) model,"In this talk I summarize the one loop and higher loop calculations of the
effective equations of motion of the O(N) symmetric scalar model in the linear
response approximation. At one loop one finds essential difference in long time
behavior for the fields below and above a dynamically generated length scale. A
partial resummation assuming quasi-particle propagation seems to cancel the
relevance of this scale.",0010290v1
2001-07-16,A generating functional for ultrasoft amplitudes in hot QCD,"The effective amplitudes for gluon momentum p<<gT in hot QCD exhibit damping
as a result of collisions. The whole set of n-point amplitudes is shown to be
generated from one functional K(x,y;A), in addition to the induced current
j(x;A).",0107168v2
2004-11-01,Brane inflation with dark reheating,"In brane world scenarios inflationary vacuum energy may escape into the
higher dimensional bulk leaving behind a dark radiation effect on the brane.
The paper analyses the damping of an inflaton by massless bulk scalar radiation
and the production of dark radiation in a Randall-Sundrum type of model.",0411021v1
2005-04-14,Monopolonium in confining phase,"This paper has been withdrawn by the author(s), due the following reasons. A
similar system for a different purpose has already been studied in
Phys.Rev.D60:083001,1999 (astro-ph/9904315). Moreover, our analysis was wrong
because we have missed the large frictional forces that will rapidly damp out
the energy in the oscillating monopolonium system.",0504108v2
2005-06-03,MINT - A Simple Model for Low Energy Hadronic Interactions,"The bulk of inelastic hadronic interactions is characterized by longitudinal
phase space and exponentially damped transverse momentum spectra. A simple
model with only a single adjustable parameter is presented, making it a very
convenient tool for systematic studies, which gives a surprisingly good
description of pA-collisions at 920 GeV beam energy.",0506028v1
1996-05-17,Non-Abelian Kubo Formula and the Multiple Time-Scale Method,"The non-Abelian Kubo formula is derived from the kinetic theory. That
expression is compared with the one obtained using the eikonal for a
Chern-Simons theory. The multiple time-scale method is used to solve the
non-Abelian Kubo formula, and the damping rate for longitudinal color waves is
computed.",9605120v1
1996-10-02,Self-consistent determination of hard modes in hot QCD,"We determine self-consistently the hard-quark and hard-gluon modes in hot
QCD. The damping-rate part in resummed hard-quark or hard-gluon propagators,
rather than the thermal-mass part, plays the dominant role.",9610010v1
2000-11-06,Note on Open String/D-brane System and Noncommutative Soliton,"This is a summary of a series of papers hep-th/9910263,0005283,0010066
written with B. Chen, T. Matsuo and K. Murakami on a p-p', (p<p^{\prime}) open
string with B_{ij} field, which has led us to the explicit identification of
the Dp-brane with the noncommutative projector soliton via the gaussian damping
factor. A lecture given at Summer Institute 2000, FujiYoshida, Yamanashi,
Japan, at August 7-14, 2000.",0011028v1
2002-10-11,A simple mechanical analog of the field theory of tachyon matter,"In this brief note we show that the zero dimensional version of the field
theory of tachyon matter proposed by Sen, provides an action integral
formulation for the motion of a particle in the presence of Newtonian gravity
and nonlinear damping (quadratic in velocity).",0210108v2
2003-07-01,Highly damped quasinormal modes of Kerr black holes,"Motivated by recent suggestions that highly damped black hole quasinormal
modes (QNM's) may provide a link between classical general relativity and
quantum gravity, we present an extensive computation of highly damped QNM's of
Kerr black holes. We do not limit our attention to gravitational modes, thus
filling some gaps in the existing literature. The frequency of gravitational
modes with l=m=2 tends to \omega_R=2 \Omega, \Omega being the angular velocity
of the black hole horizon. If Hod's conjecture is valid, this asymptotic
behaviour is related to reversible black hole transformations. Other highly
damped modes with m>0 that we computed do not show a similar behaviour. The
real part of modes with l=2 and m<0 seems to asymptotically approach a constant
value \omega_R\simeq -m\varpi, \varpi\simeq 0.12 being (almost) independent of
a. For any perturbing field, trajectories in the complex plane of QNM's with
m=0 show a spiralling behaviour, similar to the one observed for
Reissner-Nordstrom (RN) black holes. Finally, for any perturbing field, the
asymptotic separation in the imaginary part of consecutive modes with m>0 is
given by 2\pi T_H (T_H being the black hole temperature). We conjecture that
for all values of l and m>0 there is an infinity of modes tending to the
critical frequency for superradiance (\omega_R=m) in the extremal limit.
Finally, we study in some detail modes branching off the so--called
``algebraically special frequency'' of Schwarzschild black holes. For the first
time we find numerically that QNM multiplets emerge from the algebraically
special Schwarzschild modes, confirming a recent speculation.",0307013v2
2004-01-22,Noncommutative inflation and the large-scale damping in the CMB anisotropy,"We show that a certain class of short-distance cutoff can give rise to large
suppression on the CMB anisotropies at large angular scales.",0401153v2
2006-05-19,Energy Loss of Heavy Quarks from Asymptotically AdS Geometries,"We investigate some universal features of AdS/CFT models of heavy quark
energy loss. In addition, as a specific example, we examine quark damping in
the spinning D3-brane solution dual to N=4 SU(N_c) super Yang-Mills at finite
temperature and R-charge chemical potential.",0605191v2
2003-06-30,Damped oscillatory integrals and boundedness of maximal operators associated to mixed homogeneous hypersurfaces,"We study the boundedness problem for maximal operators in 3-dimensional
Euclidean space associated to hypersurfaces given as the graph of $c+f$, where
$f$ is a mixed homogeneous function which is smooth away from the origin and
$c$ is a constant. Our result generalizes a corresponding theorem on mixed
homogeneous polynomial functions by A. Iosevich and E. Sawyer.",0306429v1
2003-12-19,Energy Decay of Damped Systems,"We present a new and simple bound for the exponential decay of second order
systems using the spectral shift. This result is applied to finite matrices as
well as to partial differential equations of Mathematical Physics. The type of
the generated semigroup is shown to be bounded by the upper real part of the
numerical range of the underlying quadratic operator pencil.",0312376v1
2004-04-06,Bounds for contractive semigroups and second order systems,"We derive a uniform bound for the difference of two contractive semigroups,
if the difference of their generators is form-bounded by the Hermitian parts of
the generators themselves. We construct a semigroup dynamics for second order
systems with fairly general operator coefficients and apply our bound to the
perturbation of the damping term. The result is illustrated on a dissipative
wave equation. As a consequence the exponential decay of some second order
systems is proved.",0404120v1
2006-12-07,Fractional Hamiltonian analysis of higher order derivatives systems,"The fractional Hamiltonian analysis of 1+1 dimensional field theory is
investigated and the fractional Ostrogradski's formulation is obtained. The
fractional path integral of both simple harmonic oscillator with an
acceleration-squares part and a damped oscillator are analyzed. The classical
results are obtained when fractional derivatives are replaced with the integer
order derivatives.",0612024v1
2000-02-23,Two-frequency forced Faraday waves: Weakly damped modes and pattern selection,"Recent experiments (Kudrolli, Pier and Gollub, 1998) on two-frequency
parametrically excited surface waves exhibit an intriguing ""superlattice"" wave
pattern near a codimension-two bifurcation point where both subharmonic and
harmonic waves onset simultaneously, but with different spatial wavenumbers.
The superlattice pattern is synchronous with the forcing, spatially periodic on
a large hexagonal lattice, and exhibits small-scale triangular structure.
Similar patterns have been shown to exist as primary solution branches of a
generic 12-dimensional $D_6\dot{+}T^2$-equivariant bifurcation problem, and may
be stable if the nonlinear coefficients of the bifurcation problem satisfy
certain inequalities (Silber and Proctor, 1998). Here we use the spatial and
temporal symmetries of the problem to argue that weakly damped harmonic waves
may be critical to understanding the stabilization of this pattern in the
Faraday system. We illustrate this mechanism by considering the equations
developed by Zhang and Vinals (1997, J. Fluid Mech. 336) for small amplitude,
weakly damped surface waves on a semi-infinite fluid layer. We compute the
relevant nonlinear coefficients in the bifurcation equations describing the
onset of patterns for excitation frequency ratios of 2/3 and 6/7. For the 2/3
case, we show that there is a fundamental difference in the pattern selection
problems for subharmonic and harmonic instabilities near the codimension-two
point. Also, we find that the 6/7 case is significantly different from the 2/3
case due to the presence of additional weakly damped harmonic modes. These
additional harmonic modes can result in a stabilization of the superpatterns.",0002041v2
2000-05-18,Environment-induced dynamical chaos,"We examine the interplay of nonlinearity of a dynamical system and thermal
fluctuation of its environment in the ``physical limit'' of small damping and
slow diffusion in a semiclassical context and show that the trajectories of
c-number variables exhibit dynamical chaos due to the thermal fluctuations of
the bath.",0005037v1
2003-02-12,On Whitham theory for perturbed integrable equations,"Whitham theory of modulations is developed for periodic waves described by
nonlinear wave equations integrable by the inverse scattering transform method
associated with $2\times2$ matrix or second order scalar spectral problems. The
theory is illustrated by derivation of the Whitham equations for perturbed
Korteweg-de Vries equation and nonlinear Schr\""odinger equation with linear
damping.",0302027v1
2003-02-24,Reverse Integration for Computing Stationary Points of Unstable Stiff Systems,"Using existing, forward-in-time integration schemes, we demonstrate that it
is possible to compute unstable, saddle-type fixed points of stiff systems of
ODEs when the stable compenents are fast (i.e., rapidly damped) while the
unstable components are slow. The approach has implications for the reverse
(backward in time) integration of such stiff systems, and for the coarse
reverse integration of microscopic/stochastic simulations.",0302055v1
2003-09-02,Breather lattice and its stabilization for the modified Korteweg-de Vries equation,"We obtain an exact solution for the breather lattice solution of the modified
Korteweg-de Vries (MKdV) equation. Numerical simulation of the breather lattice
demonstrates its instability due to the breather-breather interaction. However,
such multi-breather structures can be stabilized through the concurrent
application of ac driving and viscous damping terms.",0309003v1
2003-12-19,Existence of travelling waves in discrete sine-Gordon rings,"We prove existence results for travelling waves in discrete, damped,
dc-driven sine-Gordon equations with periodic boundary conditions.",0312042v5
2006-12-05,Colliding Particles in Highly Turbulent Flows,"We discuss relative velocities and the collision rate of small particles
suspended in a highly turbulent fluid. In the limit where the viscous damping
is very weak, we estimate the relative velocities using the Kolmogorov cascade
principle.",0612008v2
1998-05-29,Magnetic Faraday-Instability,"In a magnetic fluid parametrically driven surface waves can be excited by an
external oscillating magnetic field. A static magnetic field changes the
restoring forces and damping coefficients of the various surface waves. This
property enables the excitation of both subharmonic and harmonic responses of
the standing waves.",9806001v1
1999-06-08,Electromagnetic modes in cold magnetized strongly coupled plasmas,"The spectrum of electromagnetic waves propagating in a strongly coupled
magnetized fully ionized hydrogen plasma is found. The ion motion and damping
being neglected, the influence of the Coulomb coupling on the electromagnetic
spectrum is analyzed.",9906016v1
2000-08-12,The effects of the rotation in plasma,"Electric and magnetic self-fields can exist in the rotating plasma. A
self-sustained rotation can be established in the plasma. The disturbed
distribution function of rotating plasma is derived from the Vlasov equation.
The propagation of waves in rotating plasma differs from that in the usual
plasma. New terms for Landau damping appear. The local rotational behaviour may
become prevailing.",0008039v1
2000-12-11,An improved empirical equation for bunch lengthening in electron storage rings,"In this paper we propose an improved empirical equation for the bunch
lengthening in electron storage rings. The comparisons are made between the
analytical and experimental results, and the agreements are quite well. This
improved equation can be equally applied to the case where a storage ring is
very resistive (such as the improved SLC damping rings) instead of inductive as
usual.",0012020v2
2001-11-26,Methods of Laser Cooling of Electron Beams in Storage Rings,"Methods of enhanced laser cooling of particle beams in storage rings and
Robinson's damping criterion are discussed. The dynamics of amplitudes of
betatron oscillations and instantaneous orbits of electrons interacting with
laser beams being displaced in the radial direction is investigated.",0111184v2
2002-04-17,Soliton self-modulation of the turbulence amplitude and plasma rotation,"The space-uniform amplitude envelope of the Ion Temperature Gradient driven
turbulence is unstable to small perturbations and evolves to nonuniform,
soliton-like modulated profiles. The induced poloidal asymmetry of the
transport fluxes can generate spontaneous poloidal spin-up of the tokamak
plasma.",0204050v2
2002-05-06,Delayed Equation for Charged Rigid Nonrelativistic Ball,"Simple expression for self-force acting on radiating rigid charged ball is
derived (Sommerfeld ball). It is shown that appropriate delayed equation of
motion has solutions in general differ from that for Sommerfeld sphere - there
are no ""radiationless"" solutions, but there are oscillating without damping
solutions though self-force has nonzero value.",0205012v1
2003-12-10,Charge Fluctuation of Dust Grains and its Impact on Dusty Wave Propagation,"In this paper we consider the influence of dust charge fluctuations on
damping of the dust-ion-acoustic waves. Fluid approximation of longitudinal
electrostatic waves in unmagnetized plasmas is considered. We show that for a
weak acoustic wave the attenuation depends on a phenomenological charging
coefficient.",0312067v1
2004-09-03,Relativistic electron beam acceleration by Compton scattering of lower-hybrid waves,"It has been proved theoetically and numerically that the highly relativistic
electron beam can be accelerated efficiently via the Compton scattering induced
by nonlinear Landau and cyclotron damping of the lower-hybrid waves.",0409024v1
2005-07-26,On simulations of the classical harmonic oscillator equation by difference equations,"We show that any second order linear ordinary diffrential equation with
constant coefficients (including the damped and undumped harmonic oscillator
equation) admits an exact discretization, i.e., there exists a difference
equation whose solutions exactly coincide with solutions of the corresponding
differential equation evaluated at a discrete sequence of points (a lattice).
Such exact discretization is found for an arbitrary lattice spacing.",0507182v1
1998-02-16,Classical states via decoherence,"The initial states which minimize the predictability loss for a damped
harmonic oscillator are identified as quasi-free states with a symmetry
dictated by the environment's diffusion coefficients. For an isotropic
diffusion in phase space, coherent states (or mixtures of coherent states) are
selected as the most stable ones.",9802044v1
2000-01-08,Quantum computation with mesoscopic superposition states,"We present a strategy to engineer a simple cavity-QED two-bit universal
quantum gate using mesoscopic distinct quantum superposition states. The
dissipative effect on decoherence and amplitude damping of the quantum bits are
analyzed and the critical parameters are presented.",0001018v1
2001-10-03,Thermal and quantum noise in active systems,"We present a quantum network approach to the treatment of thermal and quantum
fluctuations in measurement devices. The measurement is described as a
scattering process of input fluctuations towards output ones. We present the
results obtained with this method for the treatment of a cold damped capacitive
accelerometer.",0110021v1
2001-11-24,Deformed versus undeformed cat states encoding qubit,"We study the possibility of exploiting superpositions of coherent states to
encode qubit. A comparison between the use of deformed and undeformed bosonic
algebra is made in connection with the amplitude damping errors.",0111128v1
2002-11-05,Unitary reduction of the Liouville equation relative to a two-level atom coupled to a bimodal lossy cavity,"The Liouville equation of a two-level atom coupled to a degenerate bimodal
lossy cavity is unitarily and exactly reduced to two uncoupled Liouville
equations. The first one describes a dissipative Jaynes-Cummings model and the
other one a damped harmonic oscillator. Advantages related to the reduction
method are discussed.",0211015v1
2003-11-10,Cavity Assisted Nondestructive Laser Cooling of Atomic Qubits,"We analyze two configurations for laser cooling of neutral atoms whose
internal states store qubits. The atoms are trapped in an optical lattice which
is placed inside a cavity. We show that the coupling of the atoms to the damped
cavity mode can provide a mechanism which leads to cooling of the motion
without destroying the quantum information.",0311054v2
2003-11-19,Noise enhancing the classical information capacity of a quantum channel,"We present a simple model of quantum communication where a noisy quantum
channel may benefit from the addition of further noise at the decoding stage.
We demonstrate enhancement of the classical information capacity of an
amplitude damping channel, with a predetermined detection threshold, by the
addition of noise in the decoding measurement.",0311126v1
2003-12-22,Observation of Exceptional Points in Electronic Circuits,"Two damped coupled oscillators have been used to demonstrate the occurrence
of exceptional points in a purely classical system. The implementation was
achieved with electronic circuits in the kHz-range. The experimental results
perfectly match the mathematical predictions at the exceptional point. A
discussion about the universal occurrence of exceptional points -- connecting
dissipation with spatial orientation -- concludes the paper.",0312182v1
2004-08-01,Remark on the additivity conjecture for the quantum depolarizing channel,"We consider bistochastic quantum channels generated by unitary
representations of the discret group. The proof of the additivity conjecture
for the quantum depolarizing channel $\Phi$ based on the decreasing property of
the relative entropy is given. We show that the additivity conjecture is true
for the channel $\Xi =\Psi \circ \Phi $, where $\Psi $ is the phase damping.",0408004v2
2005-03-26,Markovian feedback to control continuous variable entanglement,"We present a model to realize quantum feedback control of continuous variable
entanglement. It consists of two interacting bosonic modes subject to amplitude
damping and achieving entangled Gaussian steady state. The possibility to
greatly improve the degree of entanglement by means of Markovian (direct)
feedback is then shown.",0503206v2
2005-04-12,Generation of Werner states and preservation of entnglement in a noisy environment,"We study the influence of noisy environment on the evolution of two-atomic
system in the presence of collective damping. Generation of Werner states as
asymptotic states of evolution is described. We also show that for some initial
states the amount of entanglement is preserved during the evolution.",0504090v2
2005-04-25,Dissipative dynamics of nondegenerate two-photon Jaynes-Cummings model,"A nondegenerate two-photon Jaynes-Cummings model is investigated where the
leakage of photon through the cavity is taken into account. The effect of
cavity damping on the mean photon number, atomic populations, field statistics
and both field and atomic squeezing is considered on the basis of master
equation in dressed-state approximation for initial coherent fields and excited
atom.",0504184v1
2005-07-20,A minimal coupling method for dissipative quantum systems,"Quantum dynamics of a general dissipative system investigated by its coupling
to a Klein-Gordon type field as the environment by introducing a minimal
coupling method. As an example, the quantum dynamics of a damped three
dimensional harmonic oscillator investigated and some transition probabilities
indicating the way energy flows between the subsystems obtained. The quantum
dynamics of a dissipative two level system considered.",0507195v1
2007-02-09,Linear-optics manipulations of photon-loss codes,"We discuss codes for protecting logical qubits carried by optical fields from
the effects of amplitude damping, i.e. linear photon loss. We demonstrate that
the correctability condition for one-photon loss imposes limitations on the
range of manipulations than can be implemented with passive linear-optics
networks.",0702091v1
2007-08-27,Band-Gap Engineering of Phononic Crystals: A Computational Survey of Two-Dimensional Systems,"We present graphic results with high-levels of abstraction to desribe the
basic principles and rules of thumb for acoustic or phononic band-gap
engineering. We use these rules for developing an improved machien mount for
damping acoustic vibrations, a phononic lens and a frequency selective filter
in the acoustic regime.",0708.3669v1
2007-09-01,Comments on 'Controversy on a Dispersion Relation for MHD Waves' by Chandra and Kumthekar,"We comment on the work by Chandra and Kumthekar (2007, henceforth CK) which
is questionable. In the derivation of dispersion relation, CK neither invoke
the concept of vector space nor do they follow the basic criterion for the
elimination of perturbation terms under which the damped magnetoacoustic waves
are derived.",0709.0040v1
2007-09-17,Intrinsic dissipation in cantilevers,"We consider the effects of a velocity-independent friction force on
cantilever damping. It is shown that this dissipation mechanism causes
nonlinear effects in the cantilever vibrations. The size of the nonlinearity
increases with decreasing cantilever velocity. Our analysis makes it possible
to understand experiments [Stipe et al, PRL 87, 096801 (2001)] where an
amplitude dependence of the cantilever eigenfrequency and anomalous dissipation
was observed only at small amplitudes.",0709.2582v1
2007-09-21,Enhanced Optical Cooling of Particle Beams in Storage Rings,"A method of enhanced optical cooling (EOC) based on nonlinear selective
interaction between particles and theirs amplified undulator radiation wavelets
(URW) in storage rings is discussed. It leads to non-exponential fast damping.
The selectivity is arranged by a moving screen located on the image plane of
the optical system projecting URW there.",0709.3403v1
2007-10-26,Vacuum - induced stationary entanglement in radiatively coupled three - level atoms,"We consider a pair of three - level atoms interacting with a common vacuum
and analyze the process of entanglement production due to spontaneous emission.
We show that in the case of closely separated atoms, collective damping can
generate robust entanglement of the asymptotic states.",0710.5048v2
2007-11-15,$C^m$-theory of damped wave equations with stabilisation,"The aim of this note is to extend the energy decay estimates from [J. Wirth,
J. Differential Equations 222 (2006) 487--514] to a broader class of
time-dependent dissipation including very fast oscillations. This is achieved
using stabilisation conditions on the coefficient in the spirit of [F.
Hirosawa, Math. Ann. 339/4 (2007) 819--839].",0711.2403v1
2008-04-21,Resonant excitation amidst dephasing: An exact analytic solution,"An exact analytic solution is presented for coherent resonant excitation of a
two-state quantum system driven by a time-dependent pulsed external field with
a hyperbolic-secant shape in the presence of dephasing. Analytic results are
derived for the amplitude and the phase shift of the damped Rabi oscillations.",0804.3315v1
2008-05-06,Logarithmic decay of hyperbolic equations with arbitrary boundary damping,"In this paper, we study the logarithmic stability for the hyperbolic
equations by arbitrary boundary observation. Based on Carleman estimate, we
first prove an estimate of the resolvent operator of such equation. Then we
prove the logarithmic stability estimate for the hyperbolic equations without
any assumption on an observation subboundary.",0805.0625v1
2008-09-23,Analysis of complete positivity conditions for quantum qutrit channels,"We present an analysis of complete positivity (CP) constraints on qutrit
quantum channels that have a form of affine transformations of generalized
Bloch vector. For diagonal (damping) channels we derive conditions analogous to
the ones that in qubit case produce tetrahedron structure in the channel
parameter space.",0809.3882v3
2008-10-28,Excitation and damping of p-mode oscillations of alpha Cen B,"This paper presents an analysis of observational data on the p-mode spectrum
of the star alpha Cen B and a comparison with theoretical computations of the
stochastic excitation and damping of the modes. We find that at frequencies >
4500 micro-Hz, the model damping rates appear to be too weak to explain the
observed shape of the power spectral density of alpha Cen B. The conclusion
rests on the assumption that most of the disagreement is due to problems
modelling the damping rates, not the excitation rates, of the modes. This
assumption is supported by a parallel analysis of BiSON Sun-as-a-star data, for
which it is possible to use analysis of very long timeseries to place tight
constraints on the assumption. The BiSON analysis shows that there is a similar
high-frequency disagreement between theory and observation in the Sun.
  We demonstrate that by using suitable comparisons of theory and observation
it is possible to make inference on the dependence of the p-mode linewidths on
frequency, without directly measuring those linewidths, even though the alpha
Cen B dataset is only a few nights long. Use of independent measures from a
previous study of the alpha Cen B linewidths in two parts of its spectrum also
allows us to calibrate our linewidth estimates for the star. The resulting
calibrated linewidth curve looks similar to a frequency-scaled version of its
solar cousin, with the scaling factor equal to the ratio of the respective
acoustic cut-off frequencies of the two stars. The ratio of the frequencies at
which the onset of high-frequency problems is seen in both stars is also given
approximately by the same scaling factor.",0810.5022v1
2008-11-03,Equation of state for QCD matter in a quasiparticle model,"A phenomenological QCD quasiparticle model provides a means to map lattice
QCD results to regions relevant for a variety of heavy-ion collision
experiments at larger baryon density. We report on effects of collectives modes
and damping on the equation of state.",0811.0274v1
2009-01-14,On the use of continuous wavelet analysis for modal identification,"This paper reviews two different uses of the continuous wavelet transform for
modal identification purposes. The properties of the wavelet transform, mainly
energetic, allow to emphasize or filter the main information within measured
signals and thus facilitate the modal parameter identification especially when
mechanical systems exhibit modal coupling and/or relatively strong damping.",0901.2000v1
2009-01-20,Quasi-periodic motions in strongly dissipative forced systems,"We consider a class of ordinary differential equations describing
one-dimensional systems with a quasi-periodic forcing term and in the presence
of large damping. We discuss the conditions to be assumed on the mechanical
force and the forcing term for the existence of quasi-periodic solutions which
have the same frequency vector as the forcing.",0901.3009v1
2009-01-23,On the regularity of global attractors,"This note is focused on a novel technique in order to establish the
boundedness in more regular spaces for global attractors of dissipative
dynamical systems, without appealing to uniform-in-time estimates. As an
application of the abstract result, the semigroup generated by the strongly
damped wave equation $$u_{tt}-\Delta u_t-\Delta u+\phi(u)=f$$ with critical
nonlinearity is considered, whose attractor is shown to possess the optimal
regularity.",0901.3607v1
2009-05-07,On a Stochastic Wave Equation Driven by a Non-Gaussian Levy Process,"This paper investigates a damped stochastic wave equation driven by a
non-Gaussian Levy noise. The weak solution is proved to exist and be unique.
Moreover we show the existence of a unique invariant measure associated with
the transition semigroup under mild conditions.",0905.0992v1
2009-05-07,Metal-Enriched Plasma in Protogalactic Halos: A Survey of N V Absorption in High-z Damped & Sub-Damped Lyman-alpha Systems,"We continue our recent work to characterize the plasma content of
high-redshift damped and sub-damped Lyman-alpha systems (DLAs/sub-DLAs), which
represent multi-phase gaseous (proto)galactic disks and halos seen toward a
background source. We survey N V absorption in a sample of 91 DLAs and 18
sub-DLAs in the redshift range 1.67<z<4.28 with unblended coverage of the N V
doublet, using data from VLT/UVES, Keck/HIRES, and Keck/ESI. In DLAs, we find
eight secure N V detections, four marginal detections, and 79 non-detections.
The detection rate of N V in DLAs is therefore 13^{+5}_{-4}%. Two sub-DLA N V
detections are found among a sample of 18, at a similar detection rate of
11^{+15}_{-7}%. We show that the N V detection rate is a strong function of
metallicity, increasing by a factor of ~4 at [N/H]=[NI/HI]>-2.3. The N V and
CIV component b-value distributions in DLAs are statistically similar, but the
median b(N V) of 18 km/s is lower than the median b(O VI) of 25 km/s. Some ~20%
of the N V components have b<10 km/s and thus arise in warm photoionized plasma
at log (T/K)<4.92; local sources of ionizing radiation (as opposed to the
extragalactic background) are required to keep the cloud sizes physically
reasonable. The nature of the remaining ~80% of (broad) N V components is
unclear; models of radiatively-cooling collisionally-ionized plasma at
log(T/K)=5.2-5.4 are fairly successful in reproducing the observed integrated
high-ion column density ratios and the component line widths, but we cannot
rule out photoionization by local sources. Finally, we identify several unusual
DLAs with extremely low metallicity (<0.01 solar) but strong high-ion
absorption [log N(N V)>14 or log N(O VI)>14.2] that present challenges to
either galactic inflow or outflow models.",0905.1042v2
2009-05-12,Quantum measurement with chaotic apparatus,"We study a dissipative quantum mechanical model of the projective measurement
of a qubit. We demonstrate how a correspondence limit, damped quantum
oscillator can realise chaotic-like or periodic trajectories that emerge in
sympathy with the projection of the qubit state, providing a model of the
measurement process.",0905.1867v2
2009-06-12,Tailoring the carrier mobility of semiconducting nanowires by remote dielectrics,"The dielectric environment of thin semiconductor nanowires can affect the
charge transport properties inside the wire. In this work, it is shown that
Coulomb impurity scattering inside thin nanowires can be damped strongly by
coating the wire with a high-k dielectric. This will lead to an increase in the
mobility of free charges inside the wire.",0906.2371v1
2009-10-22,Modelling collisions in a relativistic plasma,"Generalising the work of Lenard and Bernstein, we introduce a new, fully
relativistic model to describe collisional plasmas. Like the Fokker-Planck
operator, this equation represents velocity diffusion and conserves particle
number. However, unlike the Fokker-Planck operator it is linear in the
distribution function, and so more amenable to a fluid treatment. By taking
moments, we derive a new fluid model, and demonstrate the damping effects of
collisions on Langmuir waves.",0910.4368v1
2009-11-24,Non-Markovian master equation for a damped driven two-state system,"We present a detailed microscopic derivation for a non-Markovian master
equation for a driven two-state system interacting with a general structured
reservoir. The master equation is derived using the time-convolutionless
projection operator technique in the limit of weak coupling between the
two-state quantum system and its environment. We briefly discuss the Markov
approximation, the secular approximation and their validity.",0911.4600v1
2010-02-15,Analysis on Path Spaces over Riemmannian Manifolds with Boundary,"By using Hsu's multiplicative functional for the Neumann heat equation, a
natural damped gradient operator is defined for the reflecting Brownian motion
on compact manifolds with boundary. This operator is linked to quasi-invariant
flows in terms of a integration by parts formula, which leads to the standard
log-Sobolev inequality for the associated Dirichlet form on the path space.",1002.2887v1
2010-03-07,Decay of Langmuir wave in dense plasmas and warm dense matter,"The decays of the Langmuir waves in dense plasmas are computed using the
dielectric function theory widely used in the solid state physics.
  Four cases are considered: a classical plasma, a Maxwellian plasma, a
degenerate quantum plasma, and a partially degenerate plasma. The result is
considerably different from the conventional Landau damping theory.",1003.1524v2
2011-02-21,Noncommutative gauge theory and renormalisability,"We review two different noncommutative gauge models generalizing approaches
which lead to renormalizable scalar quantum field theories. One of them
implements the crucial IR damping of the gauge field propagator in the
so-called ``soft breaking'' part. We discuss one-loop renormalisability.",1102.4167v1
2011-04-10,Stabilization of the wave equation with external force,"We study the rate of decay of the energy functional of solutions of the wave
equation with localized damping and a external force. We prove that the decay
rates of the energy functional is determined from a forced differential
equation.",1104.1808v3
2011-05-01,"Set, Reset, and Retention Times for Ionic and Filamentary Mem-Resistors","A dynamic systems model has previously been proposed for mem-resistors based
on a driven damped harmonic oscillator differential equation describing
electron and ionic depletion widths in a thin semiconductor film. This paper
derives equations for set, reset, and retention times based on the previously
proposed model. Keywords- mem-resistor, RRAM, ReRAM",1105.0134v3
2011-07-30,Ion-kinetic D'Angelo mode,"An extension of hydrodynamic D'Angelo mode of inhomogeneous sheared plasma
flow along the magnetic field into the short-wavelength limit, where the
hydrodynamic treatment is not valid, has been considered. We find that D'Angelo
mode in this wavelength range is excited by inverse ion Landau damping and
becomes the shear flow driven ion-kinetic mode.",1108.0093v1
2011-12-02,On the transmission of binary bits in discrete Josephson-junction arrays,"In this work, we use supratransmission and infratransmission in the
mathematical modeling of the propagation of digital signals in weakly damped,
discrete Josephson-junction arrays, using energy-based detection criteria. Our
results show an efficient and reliable transmission of binary information.",1112.0589v1
2012-02-19,Cluster-based Superconducting Tunneling Networks,"A 2D tunneling network consisting of nanoclusters placed on a surface is
studied. It is shown that such a network is capable of transferring large
supercurrent at high temperatures. For a realistic set of parameters the
damping is quite small, and the smallness is due to strong renormalization of
the capacitance of a cluster. The critical field also turns out to be lar",1202.4132v1
2012-02-25,Design of a Fractional Order Phase Shaper for Iso-damped Control of a PHWR under Step-back Condition,"Phase shaping using fractional order (FO) phase shapers has been proposed by
many contemporary researchers as a means of producing systems with iso-damped
closed loop response due to a stepped variation in input. Such systems, with
the closed loop damping remaining invariant to gain changes can be used to
produce dead-beat step response with only rise time varying with gain. This
technique is used to achieve an active step-back in a Pressurized Heavy Water
Reactor (PHWR) where it is desired to change the reactor power to a
pre-determined value within a short interval keeping the power undershoot as
low as possible. This paper puts forward an approach as an alternative for the
present day practice of a passive step-back mechanism where the control rods
are allowed to drop during a step-back action by gravity, with release of
electromagnetic clutches. The reactor under a step-back condition is identified
as a system using practical test data and a suitable Proportional plus Integral
plus Derivative (PID) controller is designed for it. Then the combined plant is
augmented with a phase shaper to achieve a dead-beat response in terms of power
drop. The fact that the identified static gain of the system depends on the
initial power level at which a step-back is initiated, makes this application
particularly suited for using a FO phase shaper. In this paper, a model of a
nuclear reactor is developed for a control rod drop scenario involving rapid
power reduction in a 500MWe Canadian Deuterium Uranium (CANDU) reactor using
AutoRegressive Exogenous (ARX) algorithm. The system identification and reduced
order modeling are developed from practical test data. For closed loop active
control of the identified reactor model, the fractional order phase shaper
along with a PID controller is shown to perform better than the present Reactor
Regulating System (RRS) due to its iso-damped nature.",1202.5657v1
2012-02-27,Simple absorbing boundary conditions for wave simulations with Smoothed Particle Hydrodynamics,"We study and implement a simple method, based on the Perfectly Matched Layer
approach, to treat non reflecting boundary conditions with the Smoothed
Particles Hydrodynamics numerical algorithm. The method is based on the concept
of physical damping. We illustrate how it works in the case of 1D and 2D time
dependent waves propagating in a finite domain.",1202.5893v1
2012-07-22,Singularity and existence to a wave system of nematic liquid crystals,"In this paper, we prove the global existence and singularity formation for a
wave system from modelling nematic liquid crystals in one space dimension. In
our model, although the viscous damping term is included, the solution with
smooth initial data still has gradient blowup in general, even when the initial
energy is arbitrarily small.",1207.5190v1
2012-07-26,Upsilon Suppression in PbPb Collisions at sqrt(s_NN) = 2.76 TeV,"We suggest that the combined effect of screening, gluon-induced dissociation,
collisional damping, and reduced feed-down explains most of the sequential
suppression of Y(nS) states that has been observed in PbPb relative to pp
collisions at sqrt(s_NN) = 2.76 TeV. The suppression is thus a clear, albeit
indirect, indication for the presence of a qgp.",1207.6227v1
2012-09-08,Local energy decay for the wave equation with nonlinear time dependent damping,"This paper addresses a wave equation on a exterior domain in R^{d}(d odd)
with nonlinear time dependent dissipation. Under a microlocal geometric
condition we prove that the decay rates of the local energy functional are
obtained by solving a nonlinear non-autonomous differential equation.",1209.1733v1
2012-09-08,Evidence for anisotropic polar nanoregions in relaxor PMN: A neutron study of the elastic constants and anomalous TA phonon damping,"We use neutron scattering to characterize the acoustic phonons in the relaxor
PMN and demonstrate the presence of an anisotropic damping mechanism directly
related to short-range, polar correlations. For a large range of temperatures
above Tc ~ 210, K, where dynamic polar correlations exist, acoustic phonons
propagating along [1\bar{1}0] and polarized along [110] (TA2 phonons) are
overdamped and softened across most of the Brillouin zone. By contrast,
acoustic phonons propagating along [100] and polarized along [001] (TA1
phonons) are overdamped and softened for only a limited range of wavevectors.
The anisotropy and temperature dependence of the acoustic phonon energy
linewidth are directly correlated with the elastic diffuse scattering,
indicating that polar nanoregions are the cause of the anomalous behavior. The
damping and softening vanish for q -> 0, i.e. for long-wavelength acoustic
phonons, which supports the notion that the anomalous damping is a result of
the coupling between the relaxational component of the diffuse scattering and
the harmonic TA phonons. Therefore, these effects are not due to large changes
in the elastic constants with temperature because the elastic constants
correspond to the long-wavelength limit. We compare the elastic constants we
measure to those from Brillouin scattering and to values reported for pure PT.
We show that while the values of C44 are quite similar, those for C11 and C12
are significantly less in PMN and result in a softening of (C11-C12) over PT.
There is also an increased elastic anisotropy (2C44/(C11-C12)) versus that in
PT. These results suggest an instability to TA2 acoustic fluctuations in
relaxors. We discuss our results in the context of the debate over the
""waterfall"" effect and show that they are inconsistent with TA-TO phonon
coupling or other models that invoke the presence of a second optic mode.",1209.1736v1
2012-12-28,Turbulence-Induced Instabilities in EP and QGP,"Polarization properties of turbulent stochastically inhomogeneous
ultrarelativistic QED plasma are studied. It is shown that the sign of
nonlinear turbulent Landau damping corresponds to an instability of the
spacelike modes and, for sufficiently large turbulent fields, to an actual
instability of a system.",1212.6555v1
2013-02-26,Spin Mixing in Spinor Fermi Gases,"We study a spinor fermionic system under the effect of spin-exchange
interaction. We focus on the interplay between the spin-exchange interaction
and the effective quadratic Zeeman shift. We examine the static and the dynamic
properties of both two- and many-body system. We find that the spin-exchange
interaction induces coherent Rabi oscillation in the two-body system, but the
oscillation is quickly damped when the system is extended to the many-body
case.",1302.6549v1
2013-03-12,Damped jump-telegraph processes,"We study a one-dimensional Markov modulated random walk with jumps. It is
assumed that amplitudes of jumps as well as a chosen velocity regime are random
and depend on a time spent by the process at a previous state of the underlying
Markov process.
  Equations for the distribution and equations for its moments are derived. We
characterise the martingale distributions in terms of observable proportions
between jump and velocity regimes.",1303.2796v1
2013-03-14,Drag and Diffusion coefficients in extreme scenarios of temperature and chemical potential,"A comparative study of high and zero temperature plasma for the case of
damping rate, drag and diffusion coefficients have been presented. In each of
these quantities, it is revealed how the magnetic interaction dominates over
the electric one at zero temperature unlike what happens at high temperature.",1303.3353v1
2013-05-19,On Collective Properties of Turbulent QED Plasma,"Polarization properties of turbulent stochastically inhomogeneous
ultrarelativistic QED plasma are studied. It is shown that the sign of
nonlinear turbulent Landau damping corresponds to an instability of the
spacelike modes and, for sufficiently large turbulent fields, to an actual
instability of a system. Modification of plasmon dispersion relations due to
turbulent effects are studied.",1305.4414v1
2013-06-17,Uniformly polynomially stable approximations for a class of second order evolution equations,"In this paper we study time semi-discrete approximations of a class of
polynomially stable infinite dimensional systems modeling the damped
vibrations. We prove that adding a suitable numerical viscosity term in the
numerical scheme, one obtains approximations that are uniformly polynomially
stable with respect to the discretization parameter.",1306.3807v1
2013-10-01,"Observations and predictions at CesrTA, and outlook for ILC","In this paper, we will describe some of the recent experimental measurements
[1, 2, 3] performed at CESRTA [4], and the supporting simulations, which probe
the interaction of the electron cloud with the stored beam. These experiments
have been done over a wide range of beam energies, emittances, bunch currents,
and fill patterns, to gather sufficient information to be able to fully
characterize the beam-electron-cloud interaction and validate the simulation
programs. The range of beam conditions is chosen to be as close as possible to
those of the ILC damping ring, so that the validated simulation programs can be
used to predict the performance of these rings with regard to electroncloud-
related phenomena. Using the new simulation code Synrad3D to simulate the
synchrotron radiation environment, a vacuum chamber design has been developed
for the ILC damping ring which achieves the required level of photoelectron
suppression. To determine the expected electron cloud density in the ring, EC
buildup simulations have been done based on the simulated radiation environment
and on the expected performance of the ILC damping ring chamber mitigation
prescriptions. The expected density has been compared with analytical estimates
of the instability threshold, to verify that the ILC damping ring vacuum
chamber design is adequate to suppress the electron cloud single-bunch
head-tail instability.",1310.0261v1
2013-10-27,Fundamental limitations of half-metallicicity in spintronic materials,"Zero-point spin fluctuations are shown to strongly influence the ground state
of ferromagnetic metals and to impose limitations for the fully spin polarized
state assumed in half-metallic ferromagnets, which may influence their
applications in spintronics. This phenomenon leads to the low-frequency Stoner
excitations and cause strong damping and softening of magnons in
magnetoresistive manganites observed experimentally.",1310.7174v1
2013-12-13,Probing Intergalactic Neutral Hydrogen by the Lyman Alpha Red Damping Wing of Gamma-Ray Burst 130606A Afterglow Spectrum at z = 5.913,"The unprecedentedly bright optical afterglow of GRB 130606A located by Swift
at a redshift close to the reionization era (z = 5.913) provides a new
opportunity to probe the ionization status of intergalactic medium (IGM). Here
we present an analysis of the red Ly alpha damping wing of the afterglow
spectrum taken by Subaru/FOCAS during 10.4-13.2 hr after the burst. We find
that the minimal model including only the baseline power-law and HI absorption
in the host galaxy does not give a good fit, leaving residuals showing concave
curvature in 8400-8900 A with an amplitude of about 0.6% of the flux. Such a
curvature in the short wavelength range cannot be explained either by
extinction at the host with standard extinction curves, intrinsic curvature of
afterglow spectra, or by the known systematic uncertainties in the observed
spectrum. The red damping wing by intervening HI gas outside the host can
reduce the residual by about 3 sigma statistical significance. We find that a
damped Ly alpha system is not favored as the origin of this intervening HI
absorption, from the observed Ly beta and metal absorption features. Therefore
absorption by diffuse IGM remains as a plausible explanation. A fit by a simple
uniform IGM model requires HI neutral fraction of f_HI ~ 0.1-0.5 depending on
the distance to the GRB host, implying high f_HI IGM associated with the
observed dark Gunn-Peterson (GP) troughs. This gives a new evidence that the
reionization is not yet complete at z ~ 6.",1312.3934v3
2014-01-08,Dynamic exchange via spin currents in acoustic and optical modes of ferromagnetic resonance in spin-valve structures,"Two ferromagnetic layers magnetically decoupled by a thick normal metal
spacer layer can be, nevertheless, dynamically coupled via spin currents
emitted by the spin-pump and absorbed through the spin-torque effects at the
neighboring interfaces. A decrease of damping in both layers due to a partial
compensation of the angular momentum leakage in each layer was previously
observed at the coincidence of the two ferromagnetic resonances. In case of
non-zero magnetic coupling, such a dynamic exchange will depend on the mutual
precession of the magnetic moments in the layers. A difference in the linewidth
of the resonance peaks is expected for the acoustic and optical regimes of
precession. However, the interlayer coupling hybridizes the resonance responses
of the layers and therefore can also change their linewidths. The interplay
between the two mechanisms has never been considered before. In the present
work, the joint influence of the hybridization and non-local damping on the
linewidth has been studied in weakly coupled NiFe/CoFe/Cu/CoFe/MnIr spin-valve
multilayers. It has been found that the dynamic exchange by spin currents is
different in the optical and acoustic modes, and this difference is dependent
on the interlayer coupling strength. In contrast to the acoustic precession
mode, the dynamic exchange in the optical mode works as an additional damping
source. A simulation in the framework of the Landau-Lifshitz-Gilbert formalism
for two ferromagnetic layers coupled magnetically and by spin currents has been
done to separate the effects of the non-local damping from the resonance modes
hybridization. In our samples both mechanisms bring about linewidth changes of
the same order of magnitude, but lead to a distinctly different angular
behavior. The obtained results are relevant for a broad class of coupled
magnetic multilayers with ballistic regime of the spin transport.",1401.1672v1
2014-02-01,Effects of stellar flybys on planetary systems: 3D modeling of the circumstellar disks damping effects,"Stellar flybys in star clusters are suspected to affect the orbital
architecture of planetary systems causing eccentricity excitation and orbital
misalignment between the planet orbit and the equatorial plane of the star. We
explore whether the impulsive changes in the orbital elements of planets,
caused by an hyperbolic stellar flyby, can be fully damped by the circumstellar
disk surrounding the star. The time required to disperse stellar clusters is in
fact comparable to circumstellar disk's lifetime. We have modelled in 3D a
system made of a solar type star surrounded by a low density disk with a giant
planet embedded in it approached on a hyperbolic encounter trajectory by a
second star, of similar mass and with its own disk. We focus on extreme
configurations where a very deep stellar flyby perturbs a Jovian planet on an
external orbit. This allows to test in full the ability of the disk to erase
the effects of the stellar encounter. We find that the amount of mass lost by
the disk during the stellar flyby is less than in 2D models where a single disk
was considered due to the mass exchange between the two disks at the encounter.
The damping in eccentricity is slightly faster than in 2D models and it occurs
on timescales of the order of a few kyr. The only trace of the flyby left in
the planet system, after about 10^4 yr, is a small misalignment, lower than 9
degrees, between the star equatorial plane and the planet orbit. In a realistic
model based on 3D simulations of star--planet--disk interactions, we find that
stellar flybys cannot excite significant eccentricities and inclinations of
planets in stellar clusters. The circumstellar disks hosting the planets damp
on a short timescale all the step changes in the two orbital parameters
produced during any stellar encounter. All records of past encounters are
erased.",1402.0077v1
2014-02-21,Damping of electron Zitterbewegung in carbon nanotubes,"Zitterbewegung (ZB, trembling motion) of electrons in semiconductor carbon
nanotubes is described taking into account dephasing processes. The density
matrix formalism is used for the theory. Differences between decay of ZB
oscillations due to electron localization and that due to dephasing are
discussed.",1402.5393v1
2014-04-18,Exponential mixing for the white - forced damped nonlinear wave equation,"The paper is devoted to studying the stochastic nonlinear wave (NLW) equation
in a bounded domain D $\subset$ R3. We show that the Markov process associated
with the flow of solution has a unique stationary measure $\mu$, and the law of
any solution converges to $\mu$ with exponential rate in the dual-Lipschitz
norm",1404.4697v1
2014-04-22,A unique continuation result for the plate equation and an application,"In this paper, we prove the unique continuation property for the weak
solution of the plate equation with non-smooth coefficients. Then, we apply
this result to study the global attractor for the semilinear plate equation
with a localized damping.",1404.5586v3
2014-07-11,Remark on stabilization of second order evolution equations by unbounded dynamic feedbacks and applications,"In this paper we consider second order evolution equations with unbounded
dynamic feedbacks. Under a regularity assumption we show that observability
properties for the undamped problem imply decay estimates for the damped
problem. We consider both uniform and non uniform decay properties.",1407.3070v1
2014-09-11,Eliminating flutter for clamped von Karman plates immersed in subsonic flows,"We address the long-time behavior of a non-rotational von Karman plate in an
inviscid potential flow. The model arises in aeroelasticity and models the
interaction between a thin, nonlinear panel and a flow of gas in which it is
immersed [6, 21, 23]. Recent results in [16, 18] show that the plate component
of the dynamics (in the presence of a physical plate nonlinearity) converge to
a global compact attracting set of finite dimension; these results were
obtained in the absence of mechanical damping of any type. Here we show that,
by incorporating mechanical damping the full flow-plate system, full
trajectories---both plate and flow---converge strongly to (the set of)
stationary states. Weak convergence results require ""minimal"" interior damping,
and strong convergence of the dynamics are shown with sufficiently large
damping. We require the existence of a ""good"" energy balance equation, which is
only available when the flows are subsonic. Our proof is based on first showing
the convergence properties for regular solutions, which in turn requires
propagation of initial regularity on the infinite horizon. Then, we utilize the
exponential decay of the difference of two plate trajectories to show that full
flow-plate trajectories are uniform-in-time Hadamard continuous. This allows us
to pass convergence properties of smooth initial data to finite energy type
initial data. Physically, our results imply that flutter (a non-static end
behavior) does not occur in subsonic dynamics. While such results were known
for rotational (compact/regular) plate dynamics [14] (and references therein),
the result presented herein is the first such result obtained for
non-regularized---the most physically relevant---models.",1409.3308v5
2014-12-15,Optomechanical laser cooling with mechanical modulations,"We theoretically study the laser cooling of cavity optomechanics when the
mechanical resonance frequency and damping depend on time. In the regime of
weak optomechanical coupling we extend the theory of laser cooling using an
adiabatic approximation. We discuss the modifications of the cooling dynamics
and compare it with numerical simulations in a wide range of modulation
frequencies.",1412.4497v1
2015-03-08,An Analytical Formulation of Power System Oscillation Frequency,"This letter proposes an analytical approach to formulate the power system
oscillation frequency under a large disturbance. A fact is revealed that the
oscillation frequency is only the function of the oscillation amplitude when
the system's model and operating condition are fixed. Case studies also show
that this function is damping-insensitive and could be applied to an inter-area
model of a multi-machine power system.",1503.07554v1
2015-04-07,Generation of coherent spin-wave modes in Yttrium Iron Garnet microdiscs by spin-orbit torque,"Spin-orbit effects [1-4] have the potential of radically changing the field
of spintronics by allowing transfer of spin angular momentum to a whole new
class of materials. In a seminal letter to Nature [5], Kajiwara et al. showed
that by depositing Platinum (Pt, a normal metal) on top of a 1.3 $\mu$m thick
Yttrium Iron Garnet (YIG, a magnetic insulator), one could effectively transfer
spin angular momentum through the interface between these two different
materials. The outstanding feature was the detection of auto-oscillation of the
YIG when enough dc current was passed in the Pt. This finding has created a
great excitement in the community for two reasons: first, one could control
electronically the damping of insulators, which can offer improved properties
compared to metals, and here YIG has the lowest damping known in nature;
second, the damping compensation could be achieved on very large objects, a
particularly relevant point for the field of magnonics [6,7] whose aim is to
use spin-waves as carriers of information. However, the degree of coherence of
the observed auto-oscillations has not been addressed in ref. [5]. In this
work, we emphasize the key role of quasi-degenerate spin-wave modes, which
increase the threshold current. This requires to reduce both the thickness and
lateral size in order to reach full damping compensation [8] , and we show
clear evidence of coherent spin-orbit torque induced auto-oscillation in
micron-sized YIG discs of thickness 20 nm.",1504.01512v1
2015-05-01,Periodic solutions for nonlinear hyperbolic evolution systems,"We shall deal with the periodic problem for nonlinear perturbations of
abstract hyperbolic evolution equations generating an evolution system of
contractions. We prove an averaging principle for the translation along
trajectories operator associated to the nonlinear evolution system, expressed
in terms of the topological degree. The abstract results shall be applied to
the damped hyperbolic partial differential equation.",1505.00150v1
2015-05-28,"Moore-Gibson-Thompson equation with memory, part I: exponential decay of energy","We are interested in the Moore-Gibson-Thompson(MGT) equation with memory
\begin{equation}\nonumber \tau u_{ttt}+ \alpha u_{tt}+c^2\A u+b\A u_t
-\int_0^tg(t-s)\A w(s)ds=0. \end{equation} We first classify the memory into
three types. Then we study how a memory term creates damping mechanism and how
the memory causes energy decay.",1505.07523v1
2015-05-29,Fission barriers heights in A$\sim$ 200 mass region,"Statistical model analysis has been carried out for $p$ and $\alpha$ induced
fission reactions using a consistent description for fission barrier and level
density in A $\sim$ 200 mass region. A continuous damping of shell correction
with excitation energy have been considered. Extracted fission barriers agree
well with the recent microscopic-macroscopic model. The shell corrections at
the saddle point were found to be not significant.",1505.08026v1
2015-06-16,Revisit on How to Derive Asymptotic Profiles to Some Evolution Equations,"We consider the Cauchy problem in ${\bf R}^{n}$ for heat and damped wave
equations. We derive asymptotic profiles to those solutions with weighted
$L^{1,1}({\bf R}^{n})$ data by presenting a simple method.",1506.04858v1
2015-06-21,Predicting the Influence of Plate Geometry on the Eddy Current Pendulum,"We quantitatively analyze a familiar classroom demonstration, Van
Waltenhofen's eddy current pendulum, to predict the damping effect for a
variety of plate geometries from first principles. Results from conformal
mapping, finite element simulations and a simplified model suitable for
introductory classes are compared with experiments.",1506.06401v1
2015-07-19,"Alfvén wave phase-mixing in flows: Why over-dense, solar coronal, open magnetic field structures are cool?","The motivation for this study is to include the effect of plasma flow in
Alfv\'en wave (AW) damping via phase mixing and to explore the observational
implications. Our magnetohydrodynamic (MHD) simulations and analytical
calculations show that, when a background flow is present, mathematical
expressions for the AW damping via phase mixing are modified by the following
substitution: $C_A^\prime(x) \to C_A^\prime(x)+V_0^\prime(x)$, where $C_A$ and
$V_0$ are AW phase and the flow speeds, and the prime denotes a derivative in
the direction across the background magnetic field. In uniform magnetic fields
and over-dense plasma structures, where $C_A$ is smaller than in the
surrounding plasma, the flow, which is confined to the structure and going in
the same direction as the AW, reduces the effect of phase-mixing, because on
the edges of the structure $C_A^\prime$ and $V_0^\prime$ have opposite signs.
Thus, the wave damps by means of slower phase-mixing compared to the case
without the flow. This is the result of the co-directional flow that reduces
the wave front stretching in the transverse direction. We apply our findings to
addressing the question why over-dense solar coronal open magnetic field
structures (OMFS) are cooler than the background plasma. Observations show that
the over-dense OMFS (e.g. solar coronal polar plumes) are cooler than
surrounding plasma and that, in these structures, Doppler line-broadening is
consistent with bulk plasma motions, such as AW. If over-dense solar coronal
OMFS are heated by AW damping via phase-mixing, we show that, co-directional
with AW, plasma flow in them reduces the phase-mixing induced-heating, thus
providing an explanation of why they appear cooler than the background.",1507.05293v2
2015-09-28,Linear inviscid damping for a class of monotone shear flow in Sobolev spaces,"In this paper, we prove the decay estimates of the velocity and $H^1$
scattering for the 2D linearized Euler equations around a class of monotone
shear flow in a finite channel. Our result is consistent with the decay rate
predicted by Case in 1960.",1509.08228v1
2015-10-09,Energy Dissipation and Landau Damping in Two- and Three-Dimensional Plasma Turbulence,"Plasma turbulence is ubiquitous in space and astrophysical plasmas, playing
an important role in plasma energization, but the physical mechanisms leading
to dissipation of the turbulent energy remain to be definitively identified.
Kinetic simulations in two dimensions (2D) have been extensively used to study
the dissipation process. How the limitation to 2D affects energy dissipation
remains unclear. This work provides a model of comparison between two- and
three-dimensional (3D) plasma turbulence using gyrokinetic simulations; it also
explores the dynamics of distribution functions during the dissipation process.
It is found that both 2D and 3D nonlinear gyrokinetic simulations of a low-beta
plasma generate electron velocity-space structures with the same
characteristics as that of linear Landau damping of Alfv\'en waves in a 3D
linear simulation. The continual occurrence of the velocity-space structures
throughout the turbulence simulations suggests that the action of Landau
damping may be responsible for the turbulent energy transfer to electrons in
both 2D and 3D, and makes possible the subsequent irreversible heating of the
plasma through collisional smoothing of the velocity-space fluctuations.
Although, in the 2D case where variation along the equilibrium magnetic field
is absent, it may be expected that Landau damping is not possible, a common
trigonometric factor appears in the 2D resonant denominator, leaving the
resonance condition unchanged from the 3D case. The evolution of the 2D and 3D
cases is qualitatively similar. However, quantitatively the nonlinear energy
cascade and subsequent dissipation is significantly slower in the 2D case.",1510.02842v2
2015-10-10,Boundary layers and incompressible Navier-Stokes-Fourier limit of the Boltzmann Equation in Bounded Domain (I),"We establish the incompressible Navier-Stokes-Fourier limit for solutions to
the Boltzmann equation with a general cut-off collision kernel in a bounded
domain. Appropriately scaled families of DiPerna-Lions-(Mischler) renormalized
solutions with Maxwell reflection boundary conditions are shown to have
fluctuations that converge as the Knudsen number goes to zero. Every limit
point is a weak solution to the Navier-Stokes-Fourier system with different
types of boundary conditions depending on the ratio between the accommodation
coefficient and the Knudsen number. The main new result of the paper is that
this convergence is strong in the case of Dirichlet boundary condition. Indeed,
we prove that the acoustic waves are damped immediately, namely they are damped
in a boundary layer in time. This damping is due to the presence of viscous and
kinetic boundary layers in space. As a consequence, we also justify the first
correction to the infinitesimal Maxwellian that one obtains from the
Chapman-Enskog expansion with Navier-Stokes scaling.
  This extends the work of Golse and Saint-Raymond \cite{Go-Sai04, Go-Sai05}
and Levermore and Masmoudi \cite{LM} to the case of a bounded domain. The case
of a bounded domain was considered by Masmoudi and Saint-Raymond \cite{M-S} for
linear Stokes-Fourier limit and Saint-Raymond \cite{SRM} for Navier-Stokes
limit for hard potential kernels. Both \cite{M-S} and \cite{SRM} didn't study
the damping of the acoustic waves. This paper extends the result of \cite{M-S}
and \cite{SRM} to the nonlinear case and includes soft potential kernels. More
importantly, for the Dirichlet boundary condition, this work strengthens the
convergence so as to make the boundary layer visible. This answers an open
problem proposed by Ukai \cite{Ukai}.",1510.02977v1
2015-11-12,Global weak solutions to 3D compressible Navier-Stokes-Poisson equations with density-dependent viscosity,"Global-in-time weak solutions to the Compressible Navier-Stokes-Poisson
equations in a three-dimensional torus for large data are considered in this
paper. The system takes into account density-dependent viscosity and
non-monotone presseur. We prove the existence of global weak solutions to NSP
equations with damping term by using the Faedo-Galerkin method and the
compactness arguments on the condition that the adiabatic constant satisfies
$\gamma>\frac{4}{3}$.",1511.03841v1
2015-11-18,Temperature cooling in quantum dissipation channel and the correspondimg thermal vacuum state,"We examine temperature cooling of optical chaotic light in a quantum
dissipation channel with the damping parameter k.The way we do it is by
introducing its thermal vacuum state which can expose entangling effect between
the system and the reservoir. The temperature cooling formula is derived, which
depends on the parameter k, by adjusting k one can control temperature.",1511.05777v1
2016-01-30,Quantum Dynamics of Complex Hamiltonians,"Non hermitian Hamiltonians play an important role in the study of dissipative
quantum systems. We show that using states with time dependent normalization
can simplify the description of such systems especially in the context of the
classical limit. We apply this prescription to study the damped harmonic
oscillator system. This is then used to study the problem of radiation in leaky
cavity.",1602.00157v2
2016-02-17,Instability of a witness bunch in a plasma bubble,"The stability of a trailing witness bunch, accelerated by a plasma wake
accelerator (PWA) in a blow-out regime, is discussed. The instability growth
rate as well as the energy spread, required for BNS damping, are obtained. A
relationship between the PWA power efficiency and the BNS energy spread is
derived.",1602.05260v2
2016-02-25,Strong Ly alpha Emission in the Proximate Damped Ly alpha Absorption Trough toward the Quasar SDSS J095253.83+011422.0,"SDSS J095253.83+011422.0 (SDSS J0952+0114) was reported by Hall et al. (2004)
as an exotic quasar at $z_{\rm em}=3.020$. In contrast to prominent broad
metal--line emissions with FWHM~9000 km/s, only a narrow Ly \alpha emission
line is present with FWHM~1000 km/s. The absence of broad Ly alpha emission
line has been a mystery for more than a decade. In this paper, we demonstrate
that this is due to dark Proximate Damped Ly alpha Absorption (PDLA) at $z_{\rm
abs}=3.010$ by identifying associated Lyman absorption line series from the
damped Ly beta up to Ly9, as well as the Lyman limit absorption edge. The PDLA
cloud has a column density of $\log N_{\rm H\,I}({\rm cm}^{-2})=21.8\pm0.2$, a
metallicity of [Zn/H]$>-1.0$, and a spatial extent exceeding the Narrow
Emission Line Region (NELR) of the quasar. With a luminosity of $L_{{\rm
Ly}\alpha}\sim10^{45}$ erg s$^{-1}$, the residual Ly alpha emission superposed
on the PDLA trough is of two orders of magnitude stronger than previous
reports. This is best explained as re-radiated photons arising from the quasar
outflowing gas at a scale larger than the NELR. The PDLA here, acting like a
natural coronagraph, provides us with a good insight into the illuminated gas
in the vicinity of the quasar, which are usually hard to resolve due to their
small size and ""seeing fuzz"" of bright quasars. Notably, SDSS J0952+0114
analogs might be easily omitted in the spectroscopic surveys of DLAs and PDLAs,
as their damped Ly alpha troughs can be fully filled by additional strong Ly
alpha emissions. Our preliminary survey shows that such systems are not very
rare. They are potentially a unique sample for probing strong quasar feedback
phenomena in the early universe.",1602.07880v2
2016-03-27,Evolution of One-Dimensional Wind-Driven Sea Spectra,"We analyze modern operational models of wind wave prediction on the subject
for compliance dissipation. Our numerical simulations from the ""first
principle"" demonstrate that heuristic formulas for damping rate of free wind
sea due to ""white capping"" (or wave breaking) dramatically exaggerates the role
of this effect in these models.",1603.08229v1
2016-03-07,Faddeev-Jackiw Quantization of Non-Autonomous Singular Systems,"We extend the quantization \`a la Faddeev-Jackiw for non-autonomous singular
systems. This leads to a generalization of the Schr\""odinger equation for those
systems. The method is exemplified by the quantization of the damped harmonic
oscillator and the relativistic particle in an external electromagnetic field.",1603.08407v1
2016-06-24,Mixing for the Burgers equation driven by a localised two-dimensional stochastic forcing,"We consider the one-dimensional Burgers equation perturbed by a stochastic
forcing, which is assumed to be white in time and localised and low-dimensional
in space. We establish a mixing property for the Markov process associated with
the problem in question. The proof is based on a general criterion for mixing
and a recent result on global approximate controllability to trajectories for
damped conservation laws.",1606.07763v1
2016-07-01,Randomized block proximal damped Newton method for composite self-concordant minimization,"In this paper we consider the composite self-concordant (CSC) minimization
problem, which minimizes the sum of a self-concordant function $f$ and a
(possibly nonsmooth) proper closed convex function $g$. The CSC minimization is
the cornerstone of the path-following interior point methods for solving a
broad class of convex optimization problems. It has also found numerous
applications in machine learning. The proximal damped Newton (PDN) methods have
been well studied in the literature for solving this problem that enjoy a nice
iteration complexity. Given that at each iteration these methods typically
require evaluating or accessing the Hessian of $f$ and also need to solve a
proximal Newton subproblem, the cost per iteration can be prohibitively high
when applied to large-scale problems. Inspired by the recent success of block
coordinate descent methods, we propose a randomized block proximal damped
Newton (RBPDN) method for solving the CSC minimization. Compared to the PDN
methods, the computational cost per iteration of RBPDN is usually significantly
lower. The computational experiment on a class of regularized logistic
regression problems demonstrate that RBPDN is indeed promising in solving
large-scale CSC minimization problems. The convergence of RBPDN is also
analyzed in the paper. In particular, we show that RBPDN is globally convergent
when $g$ is Lipschitz continuous. It is also shown that RBPDN enjoys a local
linear convergence. Moreover, we show that for a class of $g$ including the
case where $g$ is Lipschitz differentiable, RBPDN enjoys a global linear
convergence. As a striking consequence, it shows that the classical damped
Newton methods [22,40] and the PDN [31] for such $g$ are globally linearly
convergent, which was previously unknown in the literature. Moreover, this
result can be used to sharpen the existing iteration complexity of these
methods.",1607.00101v1
2017-03-20,Recovery of the starting times of delayed signals,"We present a new method to locate the starting points in time of an arbitrary
number of (damped) delayed signals. For a finite data sequence, the method
permits to first locate the starting point of the component with the longest
delay, and then --by iteration-- all the preceding ones. Numerical examples are
given and noise sensitivity is tested for weak noise.",1703.07001v1
2018-04-05,Finite time blow up for wave equations with strong damping in an exterior domain,"We consider the initial boundary value problem in exterior domain for
semilinear wave equations with power-type nonlinearity |u| p. We will establish
blow-up results when p is less than or equal to Strauss' exponent which is the
same one for the whole space case R n .",1804.01689v1
2018-04-13,Well-posedness and long time behavior of singular Langevin stochastic differential equations,"In this paper, we study damped Langevin stochastic differential equations
with singular velocity fields. We prove the strong well-posedness of such
equations. Moreover, by combining the technique of Lyapunov functions with
Krylov's estimate, we also establish the exponential ergodicity for the unique
strong solution.",1804.05086v2
2018-04-27,Contribution of phase-mixing of Alfvén waves to coronal heating in multi-harmonic loop oscillations,"Kink oscillations of a coronal loop are observed and studied in detail
because they provide a unique probe into the structure of coronal loops through
MHD seismology and a potential test of coronal heating through the phase-mixing
of Alfv\'en waves. In particular, recent observations show that standing
oscillations of loops often involve also higher harmonics, beside the
fundamental mode. The damping of these kink oscillations is explained by mode
coupling with Alfv\'en waves. We investigate the consequences for wave-based
coronal heating of higher harmonics and what coronal heating observational
signatures we may use to infer the presence of higher harmonic kink
oscillations. We perform a set of non-ideal MHD simulations where the damping
of the kink oscillation of a flux tube via mode coupling is modelled. Our MHD
simulation parameters are based on the seismological inversion of an
observation for which the first three harmonics are detected. We study the
phase-mixing of Alfv\'en waves that leads to the deposition of heat in the
system, and we apply the seismological inversion techniques to the MHD
simulation output. We find that the heating due to phase-mixing of the Alfv\'en
waves triggered by the damping of the kink oscillation is relatively small,
however we can illustrate i) how the heating location drifts due to the
subsequent damping of lower order harmonics. We also address the role of the
higher order harmonics and the width of the boundary shell in the energy
deposition. We conclude that the coronal heating due to phase-mixing seems not
to provide enough energy to maintain the thermal structure of the solar corona
even when multi-harmonics oscillations are included, and these oscillations
play an inhibiting role in the development of smaller scale structures.",1804.10562v1
2019-05-16,Boundary control of partial differential equations using frequency domain optimization techniques,"We present a frequency domain based $H_\infty$-control strategy to solve
boundary control problems for systems governed by parabolic or hyperbolic
partial differential equation, where controllers are constrained to be
physically implementable and of simple structure suited for practical
applications. The efficiency of our technique is demonstrated by controlling a
reaction-diffusion equation with input delay, and a wave equation with boundary
anti-damping.",1905.06786v1
2019-05-20,Sharp Bounds for Oscillatory Integral Operators with Homogeneous Polynomial Phases,"We obtain sharp $L^p$ bounds for oscillatory integral operators with generic
homogeneous polynomial phases in several variables. The phases considered in
this paper satisfy the rank one condition which is an important notion
introduced by Greenleaf, Pramanik and Tang. Under certain additional
assumptions, we can establish sharp damping estimates with critical exponents
to prove endpoint $L^p$ estimates.",1905.07980v1
2020-07-19,Entanglement-Coherence and Discord-Coherence analytical relations for X states,"In this work we derive analytical relations between Entanglement and
Coherence as well as between Discord and Coherence, for Bell-diagonal states
and for X states, evolving under the action of several noise channels: Bit
Flip, Phase Damping and Depolarizing. We demonstrate that for these families,
Coherence is the fundamental correlation, that is: Coherence is necessary for
the presence of Entanglement and Discord.",2007.09792v1
2010-05-20,Cavity spin optodynamics,"The dynamics of a large quantum spin coupled parametrically to an optical
resonator is treated in analogy with the motion of a cantilever in cavity
optomechanics. New spin optodynamic phenonmena are predicted, such as
cavity-spin bistability, optodynamic spin-precession frequency shifts, coherent
amplification and damping of spin, and the spin optodynamic squeezing of light.",1005.3853v2
2013-08-21,Overstable Librations can account for the Paucity of Mean Motion Resonances among Exoplanet Pairs,"We assess the multi-planet systems discovered by the Kepler satellite in
terms of current ideas about orbital migration and eccentricity damping due to
planet-disk interactions. Our primary focus is on mean motion resonances. Only
a few percent of planet pairs are in close proximity to a resonance. However,
predicted migration rates (parameterized by $\tau_n=n/{|\dot n|}$) imply that
during convergent migration most planets would have been captured into first
order resonances. Eccentricity damping (parameterized by $\tau_e=e/{|\dot e|}$)
offers a plausible resolution. Estimates suggest $\tau_e/\tau_n\sim (h/a)^2\sim
10^{-2}$, where $h/a$ is the ratio of disk thickness to radius. Together,
eccentricity damping and orbital migration give rise to an equilibrium
eccentricity, $e_{eq}\sim(\tau_e/\tau_n)^{1/2}$. Capture is permanent provided
$e_{eq}\lesssim \mu^{1/3}$, where $\mu$ denotes the planet to star mass ratio.
But for $e_{eq}\gtrsim \mu^{1/3}$, capture is only temporary because librations
around equilibrium are overstable and lead to passage through resonance on
timescale $\tau_e$. Most Kepler planet pairs have $e_{eq}>\mu^{1/3}$. Since
$\tau_n>> \tau_e$ is the timescale for migration between neighboring
resonances, only a modest percentage of pairs end up trapped in resonances
after the disk disappears. Planet pairs close to a mean motion resonance
typically exhibit period ratios 1-2% larger than those for exact resonance. The
direction of this shift undoubtedly reflects the same asymmetry that requires
convergent migration for resonance capture. Permanent resonance capture at
these separations from exact resonance would demand $\mu
(\tau_n/\tau_e)^{1/2}\gtrsim 0.01$, a value that estimates of $\mu$ from
transit data and $(\tau_e/\tau_n)^{1/2}$ from theory are insufficient to match.
Plausible alternatives involve eccentricity damping during or after disk
dispersal. (Abridged)",1308.4688v2
2016-11-09,Witnessing quantum capacities of correlated channels,"We test a general method to detect lower bounds of the quantum channel
capacity for two-qubit correlated channels. We consider in particular
correlated dephasing, depolarising and amplitude damping channels. We show that
the method is easily implementable, it does not require a priori knowledge
about the channels, and it is very efficient, since it does not rely on full
quantum process tomography.",1611.02857v1
2018-05-23,Effect of time varying transmission rates on coupled dynamics of epidemic and awareness over multiplex network,"In the present work, a non-linear stochastic model is presented to study the
effect of time variation of transmission rates on the co-evolution of epidemics
and its corresponding awareness over a two layered multiplex network. In this
model, the infection transmission rate of a given node in the epidemic layer
depends upon its awareness probability in the awareness layer. Similarly, the
infection information transmission rate of a node in the awareness layer
depends upon its infection probability in the epidemic layer. The spread of
disease resulting from physical contacts is described in terms of SIS
(Susceptible Infected Susceptible) process over the epidemic layer and the
spread of information about the disease outbreak is described in terms of UAU
(Unaware Aware Unaware) process over the virtual interaction mediated awareness
layer. The time variation of the transmission rates and the resulting
co-evolution of these mutually competing processes is studied in terms of a
network topology depend parameter({\alpha}). Using a second order linear theory
it has been shown that in the continuous time limit, the co-evolution of these
processes can be described in terms of damped and driven harmonic oscillator
equations. From the results of the Monte-Carlo simulation, it is shown that for
the suitable choice of parameter({\alpha}), the two process can either exhibit
sustained oscillatory or damped dynamics. The damped dynamics corresponds to
the endemic state. Further, for the case of endemic state it is shown that the
inclusion of awareness layer significantly lowers the disease transmission rate
and reduces the size of epidemic. The endemic state infection probability of a
given node corresponding to the damped dynamics is found to have dependence
upon both the transmission rates as well as on both absolute intra-layer and
relative inter-layer degree of the individual nodes.",1805.08947v2
2008-07-14,A z = 3 Lyman Alpha Blob Associated with a Damped Lyman Alpha System Proximate to its Background Quasar,"We report on the discovery of a bright Lyman alpha blob associated with the
z=3 quasar SDSSJ124020.91+145535.6 which is also coincident with strong damped
Lyman alpha absorption from a foreground galaxy (a so-called proximate damped
Lyman alpha system; PDLA). The one dimensional spectrum acquired by the Sloan
Digital Sky Survey (SDSS) shows a broad Lyman alpha emission line with a FWHM ~
500 km/s and a luminosity of L_{Lya} = 3.9e43 erg/s superposed on the trough of
the PDLA. Mechanisms for powering this large Lyman alpha luminosity are
discussed. We argue against emission from HII regions in the PDLA galaxy since
this requires an excessive star-formation rate ~ 500 Msun/yr and would
correspond to the largest Lyman alpha luminosity ever measured from a damped
Lyman alpha system or starburst galaxy. We use a Monte Carlo radiative transfer
simulation to investigate the possibility that the line emission is fluorescent
recombination radiation from the PDLA galaxy powered by the ionizing flux of
the quasar, but find that the predicted Lyman alpha flux is several orders of
magnitude lower than observed. We conclude that the Lyman alpha emission is not
associated with the PDLA galaxy at all, but instead is intrinsic to the
quasar's host and similar to the extended Lyman alpha 'fuzz' which is detected
around many AGN. PDLAs are natural coronagraphs that block their background
quasar at Lyman alpha, and we discuss how systems similar to
SDSSJ124020.91+145535.6 might be used to image the neutral hydrogen in the PDLA
galaxy in silhouette against the screen of extended Lyman alpha emission from
the background quasar.",0807.2271v1
2009-12-07,Analyticity and Gevrey-class regularity for the second-grade fluid equations,"We address the global persistence of analyticity and Gevrey-class regularity
of solutions to the two and three-dimensional visco-elastic second-grade fluid
equations. We obtain an explicit novel lower bound on the radius of analyticity
of the solutions to the second-grade fluid equations that does not vanish as
$t\to \infty$. Applications to the damped Euler equations are given.",0912.1327v1
2011-11-14,Twist of fractional oscillations,"Using the method of the Laplace transform, we consider fractional
oscillations. They are obtained by the time-clock randomization of ordinary
harmonic vibrations. In contrast to sine and cosine, the functions describing
the fractional oscillations exhibit a finite number of damped oscillations with
an algebraic decay. Their fractional differential equation is derived.",1111.5298v1
2012-01-12,Superconducting elliptical cavities,"We give a brief overview of the history, state of the art, and future for
elliptical superconducting cavities. Principles of the cell shape optimization,
criteria for multi-cell structures design, HOM damping schemes and other
features are discussed along with examples of superconducting structures for
various applications.",1201.2598v1
2013-08-30,Nested Head-Tail Vlasov Solver,"Nested Head-Tail (NHT) is a Mathematica-based Vlasov solver for transverse
oscillations in multi-bunch beams. It takes into account azimuthal, radial,
coupled-bunch and beam-beam degrees of freedom, single- and inter-bunch dipole
wakes, an arbitrary damper, beam-beam effects and Landau damping.",1309.0044v3
2013-09-24,Attractors for damped quintic wave equations in bounded domains,"The dissipative wave equation with a critical quintic nonlinearity in smooth
bounded three dimensional domain is considered. Based on the recent extension
of the Strichartz estimates to the case of bounded domains, the existence of a
compact global attractor for the solution semigroup of this equation is
established. Moreover, the smoothness of the obtained attractor is also shown.",1309.6272v1
2013-09-30,Harmonic oscillator: an analysis via Fourier series,"The Fourier series method is used to solve the homogeneous equation governing
the motion of the harmonic oscillator. It is shown that the general solution to
the problem can be found in a surprisingly simple way for the case of the
simple harmonic oscillator. It is also shown that the damped harmonic
oscillator is susceptible to the analysis.",1309.7918v1
2014-05-13,Magneto-seismological insights into the penumbral chromosphere and evidence for wave damping in spicules,"The observation of propagating magneto-hydrodynamic kink waves in magnetic
structures and measurement of their properties (amplitude, phase speed) can be
used to diagnose the plasma conditions in the neighbourhood of the magnetic
structure via magneto-seismology (MS). We aim to reveal properties of the
chromosphere/Transition Region above the sunspot penumbra using this technique.
Hinode observed a sunspot as it was crossing the limb, providing a unique side
on view of the sunspot atmosphere. The presence of large spicule-like jets is
evident in \ion{Ca}{II} H images. The jets are found to support transverse wave
motions that displace the central axis, which can be interpreted as a kink
wave. The properties of a wave event are measured and used to determine the
magnetic and density stratification along the structure. We also measure the
width of the spicule and the intensity profile along the structure. The
measured wave properties reveal an initial rapid increase in amplitude with
height above the solar surface, followed by a decrease in amplitude. The MS
inversion suggests this initial increase corresponds to large changes in
density and magnetic field strength. In addition, we provide the first
measurements of spicule width with height, which confirm that the spicule under
goes rapid expansion. The measured expansion shows good agreement with the
results from the MS. The observed variations in plasma parameters are suggested
to be partly due to the presence of a gravitational stratified, ambient
atmosphere. Combining width measurements with phase speed measurements implies
the observed decrease in wave amplitude at greater heights can be explained by
wave damping. Hence, we provide the first direct evidence of wave damping in
chromospheric spicules and the quality factor of the damping is found to be
significantly smaller than estimated coronal values.",1405.3203v1
2014-05-27,Interior feedback stabilization of wave equations with dynamic boundary delay,"In this paper we consider an interior stabilization problem for the wave
equation with dynamic boundary delay.We prove some stability results under the
choice of damping operator. The proof of the main result is based on a
frequency domain method and combines a contradiction argument with the
multiplier technique to carry out a special analysis for the resolvent.",1405.6865v2
2015-12-03,Lieb-Thirring inequalities on the torus,"We consider the Lieb-Thirring inequalities on the d-dimensional torus with
arbitrary periods. In the space of functions with zero average with respect to
the shortest coordinate we prove the Lieb-Thirring inequalities for the
$\gamma$-moments of the negative eigenvalues with constants independent of
ratio of the periods. Applications to the attractors of the damped
Navier-Stokes system are given.",1512.01160v1
2016-05-06,Existence of invariant measures for the stochastic damped Schrödinger equation,"In this paper, we address the long time behaviour of solutions of the
stochastic Schrodinger equation in $\mathbb{R}^d$. We prove the existence of an
invariant measure and establish asymptotic compactness of solutions, implying
in particular the existence of an ergodic measure.",1605.02014v1
2016-05-25,"Dynamic analysis of simultaneous adaptation of force, impedance and trajectory","When carrying out tasks in contact with the environment, humans are found to
concurrently adapt force, impedance and trajectory. Here we develop a robotic
model of this mechanism in humans and analyse the underlying dynamics. We
derive a general adaptive controller for the interaction of a robot with an
environment solely characterised by its stiffness and damping, using Lyapunov
theory.",1605.07834v1
2017-09-24,Exceptional points in two simple textbook examples,"We propose to introduce the concept of exceptional points in intermediate
courses on mathematics and classical mechanics by means of simple textbook
examples. The first one is an ordinary second-order differential equation with
constant coefficients. The second one is the well known damped harmonic
oscillator. They enable one to connect the occurrence of linearly dependent
exponential solutions with a defective matrix that cannot be diagonalized but
can be transformed into a Jordan canonical form.",1710.00067v1
2017-12-05,Harnessing Electrical Power from Vortex-Induced Vibration of a Circular Cylinder,"The generation of electrical power from Vortex-Induced Vibration (VIV) of a
cylinder is investigated numerically. The cylinder is free to oscillate in the
direction transverse to the incoming flow. The cylinder is attached to a magnet
that can move along the axis of a coil made from conducting wire. The magnet
and the coil together constitute a basic electrical generator. When the
cylinder undergoes VIV, the motion of the magnet creates a voltage across the
coil, which is connected to a resistive load. By Lenz's law, induced current in
the coil applies a retarding force to the magnet. Effectively, the electrical
generator applies a damping force on the cylinder with a spatially varying
damping coefficient. For the initial investigation reported here, the Reynolds
number is restricted to Re < 200, so that the flow is laminar and
two-dimensional (2D). The incompressible 2D Navier-Stokes equations are solved
using an extensively validated spectral-element based solver. The effects of
the electromagnetic (EM) damping constant xi_m, coil dimensions (radius a,
length L), and mass ratio on the electrical power extracted are quantified. It
is found that there is an optimal value of xi_m (xi_opt) at which maximum
electrical power is generated. As the radius or length of the coil is
increased, the value of xi_opt is observed to increase. Although the maximum
average power remains the same, a larger coil radius or length results in a
more robust system in the sense that a relatively large amount of power can be
extracted when xi_m is far from xi_opt, unlike the constant damping ratio case.
The average power output is also a function of Reynolds number, primarily
through the increased maximum oscillation amplitude that occurs with increased
Reynolds number at least within the laminar range, although the general
qualitative findings seem likely to carry across to high Reynolds number VIV.",1712.01588v1
2017-12-08,An algorithm to resolve γ-rays from charged cosmic rays with DAMPE,"The DArk Matter Particle Explorer (DAMPE), also known as Wukong in China,
launched on December 17, 2015, is a new high energy cosmic ray and {\gamma}-ray
satellite-borne observatory in space. One of the main scientific goals of DAMPE
is to observe GeV-TeV high energy {\gamma}-rays with accurate energy, angular,
and time resolution, to indirectly search for dark matter particles and for the
study of high energy astrophysics. Due to the comparatively higher fluxes of
charged cosmic rays with respect to {\gamma}-rays, it is challenging to
identify {\gamma}-rays with sufficiently high efficiency minimizing the amount
of charged cosmic ray contamination. In this work we present a method to
identify {\gamma}-rays in DAMPE data based on Monte Carlo simulations, using
the powerful electromagnetic/hadronic shower discrimination provided by the
calorimeter and the veto detection of charged particles provided by the plastic
scintillation detector. Monte Carlo simulations show that after this selection
the number of electrons and protons that contaminate the selected {\gamma}-ray
events at $\sim10$ GeV amounts to less than 1% of the selected sample. Finally,
we use flight data to verify the effectiveness of the method by highlighting
known {\gamma}-ray sources in the sky and by reconstructing preliminary light
curves of the Geminga pulsar.",1712.02939v1
2017-12-27,A simple and natural interpretations of the DAMPE cosmic-ray electron/positron spectrum within two sigma deviations,"The DArk Matter Particle Explorer (DAMPE) experiment has recently announced
the first results for the measurement of total electron plus positron fluxes
between 25 GeV and 4.6 TeV. A spectral break at about 0.9 TeV and a tentative
peak excess around 1.4 TeV have been found. However, it is very difficult to
reproduce both the peak signal and the smooth background including spectral
break simultaneously. We point out that the numbers of events in the two energy
ranges (bins) close to the 1.4 TeV excess have $1\sigma$ deficits. With the
basic physics principles such as simplicity and naturalness, we consider the
$-2\sigma$, $+2\sigma$, and $-1\sigma$ deviations due to statistical
fluctuations for the 1229.3~GeV bin, 1411.4~GeV bin, and 1620.5~GeV bin.
Interestingly, we show that all the DAMPE data can be explained consistently
via both the continuous distributed pulsar and dark matter interpretations,
which have $\chi^{2} \simeq 17.2 $ and $\chi^{2} \simeq 13.9$ (for all the 38
points in DAMPE electron/positron spectrum with 3 of them revised),
respectively. These results are different from the previous analyses by
neglecting the 1.4 TeV excess. At the same time, we do a similar global fitting
on the newly released CALET lepton data, which could also be interpreted by
such configurations. Moreover, we present a $U(1)_D$ dark matter model with
Breit-Wigner mechanism, which can provide the proper dark matter annihilation
cross section and escape the CMB constraint. Furthermore, we suggest a few ways
to test our proposal.",1712.09586v6
2018-09-04,Creation of bipartite steering correlations by a fast damped auxiliary mode,"We consider a three-mode system and show how steering correlations can be
created between two modes of the system using the fast dissipation of the third
mode. These correlations result in a directional form of entanglement, called
quantum or EPR steering. We illustrate this on examples of the interactions
among damped radiation modes in an optomechanical three-mode system. By
assuming that one of the modes undergoes fast dissipation, we show that the
coupling of that mode to one or two other modes of the system may result in
one- or two-way quantum steering. Explicit analytical results are given for the
steering parameters. We find that two modes coupled by the parametric-type
interaction and damped with the same rates can be entangled but cannot exhibit
quantum steering. When, in addition, one of the modes is coupled to a fast
damped mode, steering correlations are created and the modes then exhibit
one-way steering. The creation of the steering correlations is interpreted in
the context of the variances of the quadrature components of the modes that the
steering correlations result from an asymmetry in the variances of the
quadrature components of the modes induced by the auxiliary mode. It is found
that the fluctuations act directionally that quantum steering may occur only
when the variance of the steering mode is larger that the variance of the
steered mode. The scheme is shown to be quite robust against the thermal
excitation of the modes if the fluctuations of the steering mode are larger
than the fluctuations of the steered mode.",1809.01176v1
2018-10-06,Global Well-Posedness and Global Attractor for Two-dimensional Zakharov-Kuznetsov Equation,"The initial value problem for two-dimensional Zakharov-Kuznetsov equation is
shown to be globally well-posed in $H^s({\mathbb{R}^2})$ for all
$\frac{5}{7}<s<1$ via using $I$-method in the context of atomic spaces. By
means of the increment of modified energy, the exsitence of global attractor
for weakly damped, forced Zakharov-Kuznetsov equation is also established in
$H^s({\mathbb{R}^2})$ for $\frac{10}{11}<s<1$.",1810.02984v1
2018-10-07,Uniform attractors for measure-driven quintic wave equation with periodic boundary conditions,"We give a detailed study of attractors for measure driven quintic damped wave
equations with periodic boundary conditions. This includes uniform
energy-to-Strichartz estimates, the existence of uniform attractors in a weak
or strong topology in the energy phase space, the possibility to present them
as a union of all complete trajectories, further regularity, etc.",1810.03149v1
2018-10-13,Exponential Decay in a Timoshenko-type System of Thermoelasticity of Type III with Frictional versus Viscoelatic Damping and Delay,"In this work, a Timoshenko system of type III of thermoelasticity with
frictional versus viscoelastic under Dirichlet-Dirichlet-Neumann boundary
conditions was considered. By exploiting energy method to produce a suitable
Lyapunov functional, we establish the global existence, exponential decay of
Type-III case.",1810.05820v1
2019-06-06,Well-posedness and exponential decay estimates for a Korteweg-de Vries-Burgers equation with time-delay,"We consider the KdV-Burgers equation and its linear version in presence of a
delay feedback. We prove well-posedness of the models and exponential decay
estimates under appropriate conditions on the damping coefficients. Our
arguments rely on a Lyapunov functional approach combined with a step by step
procedure and semigroup theory.",1906.02488v1
2019-06-19,Accurate Lindblad-Form Master Equation for Weakly Damped Quantum Systems Across All Regimes,"Realistic models of quantum systems must include dissipative interactions
with an environment. For weakly-damped systems the Lindblad-form Markovian
master equation is invaluable for this task due to its tractability and
efficiency. This equation only applies, however, when the frequencies of any
subset of the system's transitions are either equal (degenerate), or their
differences are much greater than the transitions' linewidths (far-detuned).
Outside of these two regimes the only available efficient description has been
the Bloch-Redfield (B-R) master equation, the efficacy of which has long been
controversial due to its failure to guarantee the positivity of the density
matrix. The ability to efficiently simulate weakly-damped systems across all
regimes is becoming increasingly important, especially in the area of quantum
technologies. Here we solve this long-standing problem. We discover that a
condition on the slope of the spectral density is sufficient to derive a
Lindblad form master equation that is accurate for all regimes. We further show
that this condition is necessary for weakly-damped systems to be described by
the B-R equation or indeed any Markovian master equation. We thus obtain a
replacement for the B-R equation over its entire domain of applicability that
is no less accurate, simpler in structure, completely positive, allows
simulation by efficient quantum trajectory methods, and unifies the previous
Lindblad master equations. We also show via exact simulations that the new
master equation can describe systems in which slowly-varying transition
frequencies cross each other during the evolution. System identification tools,
developed in systems engineering, play an important role in our analysis. We
expect these tools to prove useful in other areas of physics involving complex
systems.",1906.08279v2
2019-07-10,Heuristic construction of codeword stabilized codes,"The family of codeword stabilized codes encompasses the stabilizer codes as
well as many of the best known nonadditive codes. However, constructing optimal
$n$-qubit codeword stabilized codes is made difficult by two main factors. The
first of these is the exponential growth with $n$ of the number of graphs on
which a code can be based. The second is the NP-hardness of the maximum clique
search required to construct a code from a given graph. We address the second
of these issues through the use of a heuristic clique finding algorithm. This
approach has allowed us to find $((9,97\leq K\leq100,2))$ and $((11,387\leq
K\leq416,2))$ codes, which are larger than any previously known codes. To
address the exponential growth of the search space, we demonstrate that graphs
that give large codes typically yield clique graphs with a large number of
nodes. The number of such nodes can be determined relatively efficiently, and
we demonstrate that $n$-node graphs yielding large clique graphs can be found
using a genetic algorithm. This algorithm uses a novel spectral bisection based
crossover operation that we demonstrate to be superior to more standard
crossover operations. Using this genetic algorithm approach, we have found
$((13,18,4))$ and $((13,20,4))$ codes that are larger than any previously known
code. We also consider codes for the amplitude damping channel. We demonstrate
that for $n\leq9$, optimal codeword stabilized codes correcting a single
amplitude damping error can be found by considering standard form codes that
detect one of only three of the $3^{n}$ possible equivalent error sets. By
combining this error set selection with the genetic algorithm approach, we have
found $((11,68))$ and $((11,80))$ codes capable of correcting a single
amplitude damping error and $((11,4))$, $((12,4))$, $((13,8))$, and $((14,16))$
codes capable of correcting two amplitude damping",1907.04537v2
2019-07-10,Exponential stability for the nonlinear Schrödinger equation on a star-shaped network,"In this paper, we prove the exponential stability of the solution of the
nonlinear dissipative Schr\""odinger equation on a star-shaped network and where
the damping is localized on one branch and at the infinity.",1907.04950v1
2019-07-22,Role of charge equilibration in multinucleon transfer in damped collisions of heavy ions,"In this work, the charge equilibration process has been analyzed within the
Langevin-type dynamical approach. Its duration and energy dependence are
discussed. We have analyzed the isotopic distributions of final products
obtained in the isospin-asymmetric 58Ni,40Ca + 208Pb reactions. Comparison of
58Ni,64Ni + 208Pb systems have been done in order to analyze the final yields
of neutron-rich heavy nuclides.",1907.09352v1
2019-09-25,Neutrino decoherence in a fermion and scalar background,"We consider the decoherence effects in the propagation of neutrinos in a
background composed of a scalar particle and a fermion due to the non-forward
neutrino scattering processes. Using a simple model for the coupling of the
form $\bar f_R\nu_L\phi$ we calculate the contribution to the imaginary part of
the neutrino self-energy arising from the non-forward neutrino scattering
processes in such backgrounds, from which the damping terms are determined. In
the case we are considering, in which the initial neutrino state is depleted
but does not actually disappear (the initial neutrino transitions into a
neutrino of a different flavor but does not decay into a $f\phi$ pair, for
example), we associate the damping terms with decoherence effects. For this
purpose we give a precise prescription to identify the decoherence terms, as
used in the context of the master or Linblad equation, in terms of the damping
terms we have obtained from the calculation of the imaginary part of the
neutrino self-energy from the non-forward neutrino scattering processes. The
results can be directly useful in the context of Dark Matter-neutrino
interaction models in which the scalar and/or fermion constitute the
dark-matter, and can also serve to guide the generalizations to other models
and/or situations in which the decoherence effects in the propagation of
neutrinos originate from the non-forward scattering processes may be important.
As a guide to estimating such decoherence effects, the contributions to the
absorptive part of the self-energy and the corresponding damping terms are
computed explicitly in the context of the model we consider, for several
limiting cases of the momentum distribution functions of the background
particles.",1909.11271v2
2019-10-15,Adversarial Examples for Models of Code,"Neural models of code have shown impressive results when performing tasks
such as predicting method names and identifying certain kinds of bugs. We show
that these models are vulnerable to adversarial examples, and introduce a novel
approach for attacking trained models of code using adversarial examples. The
main idea of our approach is to force a given trained model to make an
incorrect prediction, as specified by the adversary, by introducing small
perturbations that do not change the program's semantics, thereby creating an
adversarial example. To find such perturbations, we present a new technique for
Discrete Adversarial Manipulation of Programs (DAMP). DAMP works by deriving
the desired prediction with respect to the model's inputs, while holding the
model weights constant, and following the gradients to slightly modify the
input code. We show that our DAMP attack is effective across three neural
architectures: code2vec, GGNN, and GNN-FiLM, in both Java and C#. Our
evaluations demonstrate that DAMP has up to 89% success rate in changing a
prediction to the adversary's choice (a targeted attack) and a success rate of
up to 94% in changing a given prediction to any incorrect prediction (a
non-targeted attack). To defend a model against such attacks, we empirically
examine a variety of possible defenses and discuss their trade-offs. We show
that some of these defenses can dramatically drop the success rate of the
attacker, with a minor penalty of 2% relative degradation in accuracy when they
are not performing under attack. Our code, data, and trained models are
available at https://github.com/tech-srl/adversarial-examples .",1910.07517v5
2020-01-15,Weak pseudo-bosons,"We show how the notion of {\em pseudo-bosons}, originally introduced as
operators acting on some Hilbert space, can be extended to a distributional
settings. In doing so, we are able to construct a rather general framework to
deal with generalized eigenvectors of the multiplication and of the derivation
operators. Connections with the quantum damped harmonic oscillator are also
briefly considered.",2001.05219v1
2020-02-14,Testing Physical Models for Cosmic Ray Transport Coefficients on Galactic Scales: Self-Confinement and Extrinsic Turbulence at GeV Energies,"The microphysics of ~GeV cosmic ray (CR) transport on galactic scales remain
deeply uncertain, with almost all studies adopting simple prescriptions (e.g.
constant-diffusivity). We explore different physically-motivated, anisotropic,
dynamical CR transport scalings in high-resolution cosmological FIRE
simulations of dwarf and ~$L_{\ast}$ galaxies where scattering rates vary with
local plasma properties motivated by extrinsic turbulence (ET) or
self-confinement (SC) scenarios, with varying assumptions about e.g. turbulent
power spectra on un-resolved scales, Alfven-wave damping, etc. We
self-consistently predict observables including $\gamma$-rays ($L_{\gamma}$),
grammage, residence times, and CR energy densities to constrain the models. We
demonstrate many non-linear dynamical effects (not captured in simpler models)
tend to enhance confinement. For example, in multi-phase media, even allowing
arbitrary fast transport in neutral gas does not substantially reduce CR
residence times (or $L_{\gamma}$), as transport is rate-limited by the ionized
WIM and 'inner CGM' gaseous halo ($10^{4}-10^{6}$ K gas within 10-30 kpc), and
$L_{\gamma}$ can be dominated by trapping in small 'patches.' Most physical ET
models contribute negligible scattering of ~1-10 GeV CRs, but it is crucial to
account for anisotropy and damping (especially of fast modes) or else
scattering rates would violate observations. We show that the most
widely-assumed scalings for SC models produce excessive confinement by factors
>100 in the WIM and inner CGM, where turbulent and Landau damping dominate.
This suggests either a breakdown of quasi-linear theory used to derive the CR
transport parameters in SC, or that other novel damping mechanisms dominate in
intermediate-density ionized gas.",2002.06211v2
2020-02-18,Boundary feedback control of an anti-stable wave equation,"We discuss boundary control of a wave equation with a non-linear anti-damping
boundary condition. We design structured finite-dimensional $H_\infty$-output
feedback controllers which stabilize the infinite dimensional system
exponentially in closed loop. The method is applied to control torsional
vibrations in drilling systems with the goal to avoid slip-stick.",2002.07567v1
2020-12-16,Observation of anti-damping spin-orbit torques generated by in-plane and out-of-plane spin polarizations in MnPd3,"High spin-orbit torques (SOTs) generated by topological materials and heavy
metals interfaced with a ferromagnetic layer show promise for next generation
magnetic memory and logic devices. SOTs generated from the in-plane spin
polarization along y-axis originated by the spin Hall and Edelstein effects can
switch magnetization collinear with the spin polarization in the absence of
external magnetic fields. However, an external magnetic field is required to
switch the magnetization along x and z-axes via SOT generated by y-spin
polarization. Here, we present that the above limitation can be circumvented by
unconventional SOT in magnetron-sputtered thin film MnPd3. In addition to the
conventional in-plane anti-damping-like torque due to the y-spin polarization,
out-of-plane and in-plane anti-damping-like torques originating from z-spin and
x-spin polarizations, respectively have been observed at room temperature. The
spin torque efficiency corresponding to the y-spin polarization from MnPd3 thin
films grown on thermally oxidized silicon substrate and post annealed at 400
Deg C is 0.34 - 0.44. Remarkably, we have demonstrated complete external
magnetic field-free switching of perpendicular Co layer via unconventional
out-of-plane anti-damping-like torque from z-spin polarization. Based on the
density functional theory calculations, we determine that the observed x- and
z- spin polarizations with the in-plane charge current are due to the low
symmetry of the (114) oriented MnPd3 thin films. Taken together, the new
material reported here provides a path to realize a practical spin channel in
ultrafast magnetic memory and logic devices.",2012.09315v1
2017-05-13,Eigenvalues of one-dimensional non-self-adjoint Dirac operators and applications,"We analyze eigenvalues emerging from thresholds of the essential spectrum of
one-dimensional Dirac operators perturbed by complex and non-symmetric
potentials. In the general non-self-adjoint setting we establish the existence
and asymptotics of weakly coupled eigenvalues and Lieb-Thirring inequalities.
As physical applications we investigate the damped wave equation and armchair
graphene nanoribbons.",1705.04833v1